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 basic_block force_nonfallthru_and_redirect (edge, basic_block);
73 static basic_block rtl_split_edge (edge);
74 static bool rtl_move_block_after (basic_block, basic_block);
75 static int rtl_verify_flow_info (void);
76 static basic_block cfg_layout_split_block (basic_block, void *);
77 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
78 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
79 static void cfg_layout_delete_block (basic_block);
80 static void rtl_delete_block (basic_block);
81 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
82 static edge rtl_redirect_edge_and_branch (edge, basic_block);
83 static basic_block rtl_split_block (basic_block, void *);
84 static void rtl_dump_bb (basic_block, FILE *, int);
85 static int rtl_verify_flow_info_1 (void);
86 static void mark_killed_regs (rtx, rtx, void *);
87 static void rtl_make_forwarder_block (edge);
89 /* Return true if NOTE is not one of the ones that must be kept paired,
90 so that we may simply delete it. */
93 can_delete_note_p (rtx note)
95 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
96 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK
97 || NOTE_LINE_NUMBER (note) == NOTE_INSN_UNLIKELY_EXECUTED_CODE);
100 /* True if a given label can be deleted. */
103 can_delete_label_p (rtx label)
105 return (!LABEL_PRESERVE_P (label)
106 /* User declared labels must be preserved. */
107 && LABEL_NAME (label) == 0
108 && !in_expr_list_p (forced_labels, label)
109 && !in_expr_list_p (label_value_list, label));
112 /* Delete INSN by patching it out. Return the next insn. */
115 delete_insn (rtx insn)
117 rtx next = NEXT_INSN (insn);
119 bool really_delete = true;
123 /* Some labels can't be directly removed from the INSN chain, as they
124 might be references via variables, constant pool etc.
125 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
126 if (! can_delete_label_p (insn))
128 const char *name = LABEL_NAME (insn);
130 really_delete = false;
131 PUT_CODE (insn, NOTE);
132 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
133 NOTE_DELETED_LABEL_NAME (insn) = name;
136 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
141 /* If this insn has already been deleted, something is very wrong. */
142 gcc_assert (!INSN_DELETED_P (insn));
144 INSN_DELETED_P (insn) = 1;
147 /* If deleting a jump, decrement the use count of the label. Deleting
148 the label itself should happen in the normal course of block merging. */
151 && LABEL_P (JUMP_LABEL (insn)))
152 LABEL_NUSES (JUMP_LABEL (insn))--;
154 /* Also if deleting an insn that references a label. */
157 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
158 && LABEL_P (XEXP (note, 0)))
160 LABEL_NUSES (XEXP (note, 0))--;
161 remove_note (insn, note);
166 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
167 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
169 rtx pat = PATTERN (insn);
170 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
171 int len = XVECLEN (pat, diff_vec_p);
174 for (i = 0; i < len; i++)
176 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
178 /* When deleting code in bulk (e.g. removing many unreachable
179 blocks) we can delete a label that's a target of the vector
180 before deleting the vector itself. */
182 LABEL_NUSES (label)--;
189 /* Like delete_insn but also purge dead edges from BB. */
191 delete_insn_and_edges (rtx insn)
197 && BLOCK_FOR_INSN (insn)
198 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
200 x = delete_insn (insn);
202 purge_dead_edges (BLOCK_FOR_INSN (insn));
206 /* Unlink a chain of insns between START and FINISH, leaving notes
207 that must be paired. */
210 delete_insn_chain (rtx start, rtx finish)
214 /* Unchain the insns one by one. It would be quicker to delete all of these
215 with a single unchaining, rather than one at a time, but we need to keep
219 next = NEXT_INSN (start);
220 if (NOTE_P (start) && !can_delete_note_p (start))
223 next = delete_insn (start);
231 /* Like delete_insn but also purge dead edges from BB. */
233 delete_insn_chain_and_edges (rtx first, rtx last)
238 && BLOCK_FOR_INSN (last)
239 && BB_END (BLOCK_FOR_INSN (last)) == last)
241 delete_insn_chain (first, last);
243 purge_dead_edges (BLOCK_FOR_INSN (last));
246 /* Create a new basic block consisting of the instructions between HEAD and END
247 inclusive. This function is designed to allow fast BB construction - reuses
248 the note and basic block struct in BB_NOTE, if any and do not grow
249 BASIC_BLOCK chain and should be used directly only by CFG construction code.
250 END can be NULL in to create new empty basic block before HEAD. Both END
251 and HEAD can be NULL to create basic block at the end of INSN chain.
252 AFTER is the basic block we should be put after. */
255 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
260 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
263 /* If we found an existing note, thread it back onto the chain. */
271 after = PREV_INSN (head);
275 if (after != bb_note && NEXT_INSN (after) != bb_note)
276 reorder_insns_nobb (bb_note, bb_note, after);
280 /* Otherwise we must create a note and a basic block structure. */
286 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
287 else if (LABEL_P (head) && end)
289 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
295 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
301 NOTE_BASIC_BLOCK (bb_note) = bb;
304 /* Always include the bb note in the block. */
305 if (NEXT_INSN (end) == bb_note)
310 bb->index = last_basic_block++;
312 link_block (bb, after);
313 BASIC_BLOCK (bb->index) = bb;
314 update_bb_for_insn (bb);
315 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
317 /* Tag the block so that we know it has been used when considering
318 other basic block notes. */
324 /* Create new basic block consisting of instructions in between HEAD and END
325 and place it to the BB chain after block AFTER. END can be NULL in to
326 create new empty basic block before HEAD. Both END and HEAD can be NULL to
327 create basic block at the end of INSN chain. */
330 rtl_create_basic_block (void *headp, void *endp, basic_block after)
332 rtx head = headp, end = endp;
335 /* Grow the basic block array if needed. */
336 if ((size_t) last_basic_block >= VARRAY_SIZE (basic_block_info))
338 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
339 VARRAY_GROW (basic_block_info, new_size);
344 bb = create_basic_block_structure (head, end, NULL, after);
350 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
352 basic_block newbb = rtl_create_basic_block (head, end, after);
354 initialize_bb_rbi (newbb);
358 /* Delete the insns in a (non-live) block. We physically delete every
359 non-deleted-note insn, and update the flow graph appropriately.
361 Return nonzero if we deleted an exception handler. */
363 /* ??? Preserving all such notes strikes me as wrong. It would be nice
364 to post-process the stream to remove empty blocks, loops, ranges, etc. */
367 rtl_delete_block (basic_block b)
371 /* If the head of this block is a CODE_LABEL, then it might be the
372 label for an exception handler which can't be reached.
374 We need to remove the label from the exception_handler_label list
375 and remove the associated NOTE_INSN_EH_REGION_BEG and
376 NOTE_INSN_EH_REGION_END notes. */
381 maybe_remove_eh_handler (insn);
383 /* Include any jump table following the basic block. */
385 if (tablejump_p (end, NULL, &tmp))
388 /* Include any barrier that may follow the basic block. */
389 tmp = next_nonnote_insn (end);
390 if (tmp && BARRIER_P (tmp))
393 /* Selectively delete the entire chain. */
395 delete_insn_chain (insn, end);
398 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
401 compute_bb_for_insn (void)
407 rtx end = BB_END (bb);
410 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
412 BLOCK_FOR_INSN (insn) = bb;
419 /* Release the basic_block_for_insn array. */
422 free_bb_for_insn (void)
425 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
426 if (!BARRIER_P (insn))
427 BLOCK_FOR_INSN (insn) = NULL;
430 /* Return RTX to emit after when we want to emit code on the entry of function. */
432 entry_of_function (void)
434 return (n_basic_blocks ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
437 /* Update insns block within BB. */
440 update_bb_for_insn (basic_block bb)
444 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
446 if (!BARRIER_P (insn))
447 set_block_for_insn (insn, bb);
448 if (insn == BB_END (bb))
453 /* Creates a new basic block just after basic block B by splitting
454 everything after specified instruction I. */
457 rtl_split_block (basic_block bb, void *insnp)
466 insn = first_insn_after_basic_block_note (bb);
469 insn = PREV_INSN (insn);
471 insn = get_last_insn ();
474 /* We probably should check type of the insn so that we do not create
475 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
477 if (insn == BB_END (bb))
478 emit_note_after (NOTE_INSN_DELETED, insn);
480 /* Create the new basic block. */
481 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
482 BB_COPY_PARTITION (new_bb, bb);
485 /* Redirect the outgoing edges. */
486 new_bb->succs = bb->succs;
488 FOR_EACH_EDGE (e, ei, new_bb->succs)
491 if (bb->global_live_at_start)
493 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
494 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
495 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
497 /* We now have to calculate which registers are live at the end
498 of the split basic block and at the start of the new basic
499 block. Start with those registers that are known to be live
500 at the end of the original basic block and get
501 propagate_block to determine which registers are live. */
502 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
503 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
504 COPY_REG_SET (bb->global_live_at_end,
505 new_bb->global_live_at_start);
506 #ifdef HAVE_conditional_execution
507 /* In the presence of conditional execution we are not able to update
508 liveness precisely. */
509 if (reload_completed)
511 bb->flags |= BB_DIRTY;
512 new_bb->flags |= BB_DIRTY;
520 /* Blocks A and B are to be merged into a single block A. The insns
521 are already contiguous. */
524 rtl_merge_blocks (basic_block a, basic_block b)
526 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
527 rtx del_first = NULL_RTX, del_last = NULL_RTX;
530 /* If there was a CODE_LABEL beginning B, delete it. */
531 if (LABEL_P (b_head))
533 /* Detect basic blocks with nothing but a label. This can happen
534 in particular at the end of a function. */
538 del_first = del_last = b_head;
539 b_head = NEXT_INSN (b_head);
542 /* Delete the basic block note and handle blocks containing just that
544 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
552 b_head = NEXT_INSN (b_head);
555 /* If there was a jump out of A, delete it. */
560 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
562 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
563 || prev == BB_HEAD (a))
569 /* If this was a conditional jump, we need to also delete
570 the insn that set cc0. */
571 if (only_sets_cc0_p (prev))
575 prev = prev_nonnote_insn (prev);
582 a_end = PREV_INSN (del_first);
584 else if (BARRIER_P (NEXT_INSN (a_end)))
585 del_first = NEXT_INSN (a_end);
587 /* Delete everything marked above as well as crap that might be
588 hanging out between the two blocks. */
590 delete_insn_chain (del_first, del_last);
592 /* Reassociate the insns of B with A. */
597 for (x = a_end; x != b_end; x = NEXT_INSN (x))
598 set_block_for_insn (x, a);
600 set_block_for_insn (b_end, a);
608 /* Return true when block A and B can be merged. */
610 rtl_can_merge_blocks (basic_block a,basic_block b)
612 /* If we are partitioning hot/cold basic blocks, we don't want to
613 mess up unconditional or indirect jumps that cross between hot
616 Basic block partitioning may result in some jumps that appear to
617 be optimizable (or blocks that appear to be mergeable), but which really
618 must be left untouched (they are required to make it safely across
619 partition boundaries). See the comments at the top of
620 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
622 if (flag_reorder_blocks_and_partition
623 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
624 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
625 || BB_PARTITION (a) != BB_PARTITION (b)))
628 /* There must be exactly one edge in between the blocks. */
629 return (EDGE_COUNT (a->succs) == 1
630 && EDGE_SUCC (a, 0)->dest == b
631 && EDGE_COUNT (b->preds) == 1
633 /* Must be simple edge. */
634 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
636 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
637 /* If the jump insn has side effects,
638 we can't kill the edge. */
639 && (!JUMP_P (BB_END (a))
641 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
644 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
648 block_label (basic_block block)
650 if (block == EXIT_BLOCK_PTR)
653 if (!LABEL_P (BB_HEAD (block)))
655 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
658 return BB_HEAD (block);
661 /* Attempt to perform edge redirection by replacing possibly complex jump
662 instruction by unconditional jump or removing jump completely. This can
663 apply only if all edges now point to the same block. The parameters and
664 return values are equivalent to redirect_edge_and_branch. */
667 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
669 basic_block src = e->src;
670 rtx insn = BB_END (src), kill_from;
676 /* If we are partitioning hot/cold basic blocks, we don't want to
677 mess up unconditional or indirect jumps that cross between hot
680 Basic block partitioning may result in some jumps that appear to
681 be optimizable (or blocks that appear to be mergeable), but which really
682 must be left untouched (they are required to make it safely across
683 partition boundaries). See the comments at the top of
684 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
686 if (flag_reorder_blocks_and_partition
687 && (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
688 || BB_PARTITION (src) != BB_PARTITION (target)))
691 /* Verify that all targets will be TARGET. */
692 FOR_EACH_EDGE (tmp, ei, src->succs)
693 if (tmp->dest != target && tmp != e)
696 if (tmp || !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_ordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1072 VEC_safe_insert (edge, bb->succs, 0, 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
1099 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1100 jump_block->global_live_at_end
1101 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1102 COPY_REG_SET (jump_block->global_live_at_start,
1103 target->global_live_at_start);
1104 COPY_REG_SET (jump_block->global_live_at_end,
1105 target->global_live_at_start);
1108 /* Make sure new block ends up in correct hot/cold section. */
1110 BB_COPY_PARTITION (jump_block, e->src);
1111 if (flag_reorder_blocks_and_partition
1112 && targetm.have_named_sections)
1114 if (BB_PARTITION (jump_block) == BB_COLD_PARTITION)
1116 rtx bb_note, new_note;
1117 for (bb_note = BB_HEAD (jump_block);
1118 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1119 bb_note = NEXT_INSN (bb_note))
1120 if (NOTE_P (bb_note)
1121 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1123 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1125 NOTE_BASIC_BLOCK (new_note) = jump_block;
1127 if (JUMP_P (BB_END (jump_block))
1128 && !any_condjump_p (BB_END (jump_block))
1129 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1130 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1131 (REG_CROSSING_JUMP, NULL_RTX,
1132 REG_NOTES (BB_END (jump_block)));
1136 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1137 new_edge->probability = e->probability;
1138 new_edge->count = e->count;
1140 /* Redirect old edge. */
1141 redirect_edge_pred (e, jump_block);
1142 e->probability = REG_BR_PROB_BASE;
1144 new_bb = jump_block;
1147 jump_block = e->src;
1149 e->flags &= ~EDGE_FALLTHRU;
1150 if (target == EXIT_BLOCK_PTR)
1153 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1160 rtx label = block_label (target);
1161 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1162 JUMP_LABEL (BB_END (jump_block)) = label;
1163 LABEL_NUSES (label)++;
1166 emit_barrier_after (BB_END (jump_block));
1167 redirect_edge_succ_nodup (e, target);
1169 if (abnormal_edge_flags)
1170 make_edge (src, target, abnormal_edge_flags);
1175 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1176 (and possibly create new basic block) to make edge non-fallthru.
1177 Return newly created BB or NULL if none. */
1180 force_nonfallthru (edge e)
1182 return force_nonfallthru_and_redirect (e, e->dest);
1185 /* Redirect edge even at the expense of creating new jump insn or
1186 basic block. Return new basic block if created, NULL otherwise.
1187 Abort if conversion is impossible. */
1190 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1192 if (redirect_edge_and_branch (e, target)
1193 || e->dest == target)
1196 /* In case the edge redirection failed, try to force it to be non-fallthru
1197 and redirect newly created simplejump. */
1198 return force_nonfallthru_and_redirect (e, target);
1201 /* The given edge should potentially be a fallthru edge. If that is in
1202 fact true, delete the jump and barriers that are in the way. */
1205 rtl_tidy_fallthru_edge (edge e)
1208 basic_block b = e->src, c = b->next_bb;
1212 FOR_EACH_EDGE (e2, ei, b->succs)
1216 /* ??? In a late-running flow pass, other folks may have deleted basic
1217 blocks by nopping out blocks, leaving multiple BARRIERs between here
1218 and the target label. They ought to be chastized and fixed.
1220 We can also wind up with a sequence of undeletable labels between
1221 one block and the next.
1223 So search through a sequence of barriers, labels, and notes for
1224 the head of block C and assert that we really do fall through. */
1226 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1230 /* Remove what will soon cease being the jump insn from the source block.
1231 If block B consisted only of this single jump, turn it into a deleted
1236 && (any_uncondjump_p (q)
1237 || (EDGE_SUCC (b, 0) == e && ei.index == EDGE_COUNT (b->succs) - 1)))
1240 /* If this was a conditional jump, we need to also delete
1241 the insn that set cc0. */
1242 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1248 /* We don't want a block to end on a line-number note since that has
1249 the potential of changing the code between -g and not -g. */
1250 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1254 /* Selectively unlink the sequence. */
1255 if (q != PREV_INSN (BB_HEAD (c)))
1256 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1258 e->flags |= EDGE_FALLTHRU;
1261 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1262 is back edge of syntactic loop. */
1265 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1274 /* ??? Could we guarantee that bb indices are monotone, so that we could
1275 just compare them? */
1276 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1282 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1283 insn = NEXT_INSN (insn))
1286 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1288 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1295 /* Should move basic block BB after basic block AFTER. NIY. */
1298 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1299 basic_block after ATTRIBUTE_UNUSED)
1304 /* Split a (typically critical) edge. Return the new block.
1305 Abort on abnormal edges.
1307 ??? The code generally expects to be called on critical edges.
1308 The case of a block ending in an unconditional jump to a
1309 block with multiple predecessors is not handled optimally. */
1312 rtl_split_edge (edge edge_in)
1317 /* Abnormal edges cannot be split. */
1318 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1320 /* We are going to place the new block in front of edge destination.
1321 Avoid existence of fallthru predecessors. */
1322 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1327 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1328 if (e->flags & EDGE_FALLTHRU)
1332 force_nonfallthru (e);
1335 /* Create the basic block note.
1337 Where we place the note can have a noticeable impact on the generated
1338 code. Consider this cfg:
1348 If we need to insert an insn on the edge from block 0 to block 1,
1349 we want to ensure the instructions we insert are outside of any
1350 loop notes that physically sit between block 0 and block 1. Otherwise
1351 we confuse the loop optimizer into thinking the loop is a phony. */
1353 if (edge_in->dest != EXIT_BLOCK_PTR
1354 && PREV_INSN (BB_HEAD (edge_in->dest))
1355 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1356 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1357 == NOTE_INSN_LOOP_BEG)
1358 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1359 before = PREV_INSN (BB_HEAD (edge_in->dest));
1360 else if (edge_in->dest != EXIT_BLOCK_PTR)
1361 before = BB_HEAD (edge_in->dest);
1365 /* If this is a fall through edge to the exit block, the blocks might be
1366 not adjacent, and the right place is the after the source. */
1367 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1369 before = NEXT_INSN (BB_END (edge_in->src));
1372 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1373 before = NEXT_INSN (before);
1374 bb = create_basic_block (before, NULL, edge_in->src);
1375 BB_COPY_PARTITION (bb, edge_in->src);
1379 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1380 /* ??? Why not edge_in->dest->prev_bb here? */
1381 BB_COPY_PARTITION (bb, edge_in->dest);
1384 /* ??? This info is likely going to be out of date very soon. */
1385 if (edge_in->dest->global_live_at_start)
1387 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1388 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1389 COPY_REG_SET (bb->global_live_at_start,
1390 edge_in->dest->global_live_at_start);
1391 COPY_REG_SET (bb->global_live_at_end,
1392 edge_in->dest->global_live_at_start);
1395 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1397 /* For non-fallthru edges, we must adjust the predecessor's
1398 jump instruction to target our new block. */
1399 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1401 edge redirected = redirect_edge_and_branch (edge_in, bb);
1402 gcc_assert (redirected);
1405 redirect_edge_succ (edge_in, bb);
1410 /* Queue instructions for insertion on an edge between two basic blocks.
1411 The new instructions and basic blocks (if any) will not appear in the
1412 CFG until commit_edge_insertions is called. */
1415 insert_insn_on_edge (rtx pattern, edge e)
1417 /* We cannot insert instructions on an abnormal critical edge.
1418 It will be easier to find the culprit if we die now. */
1419 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1421 if (e->insns.r == NULL_RTX)
1424 push_to_sequence (e->insns.r);
1426 emit_insn (pattern);
1428 e->insns.r = get_insns ();
1432 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1433 registers that are killed by the store. */
1435 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1437 regset killed = data;
1440 if (GET_CODE (reg) == SUBREG)
1441 reg = SUBREG_REG (reg);
1444 regno = REGNO (reg);
1445 if (regno >= FIRST_PSEUDO_REGISTER)
1446 SET_REGNO_REG_SET (killed, regno);
1449 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1450 SET_REGNO_REG_SET (killed, regno + i);
1454 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1455 it checks whether this will not clobber the registers that are live on the
1456 edge (i.e. it requires liveness information to be up-to-date) and if there
1457 are some, then it tries to save and restore them. Returns true if
1460 safe_insert_insn_on_edge (rtx insn, edge e)
1463 regset_head killed_head;
1464 regset killed = INITIALIZE_REG_SET (killed_head);
1465 rtx save_regs = NULL_RTX;
1466 int regno, noccmode;
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_operation (killed, killed, e->dest->global_live_at_start,
1482 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno, rsi)
1484 mode = regno < FIRST_PSEUDO_REGISTER
1485 ? reg_raw_mode[regno]
1486 : GET_MODE (regno_reg_rtx[regno]);
1487 if (mode == VOIDmode)
1490 if (noccmode && mode == CCmode)
1493 save_regs = alloc_EXPR_LIST (0,
1496 gen_raw_REG (mode, regno)),
1505 for (x = save_regs; x; x = XEXP (x, 1))
1507 from = XEXP (XEXP (x, 0), 1);
1508 to = XEXP (XEXP (x, 0), 0);
1509 emit_move_insn (to, from);
1512 for (x = save_regs; x; x = XEXP (x, 1))
1514 from = XEXP (XEXP (x, 0), 0);
1515 to = XEXP (XEXP (x, 0), 1);
1516 emit_move_insn (to, from);
1518 insn = get_insns ();
1520 free_EXPR_LIST_list (&save_regs);
1522 insert_insn_on_edge (insn, e);
1524 FREE_REG_SET (killed);
1528 /* Update the CFG for the instructions queued on edge E. */
1531 commit_one_edge_insertion (edge e, int watch_calls)
1533 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1534 basic_block bb = NULL;
1536 /* Pull the insns off the edge now since the edge might go away. */
1538 e->insns.r = NULL_RTX;
1540 /* Special case -- avoid inserting code between call and storing
1541 its return value. */
1542 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1543 && EDGE_COUNT (e->dest->preds) == 1
1544 && e->src != ENTRY_BLOCK_PTR
1545 && CALL_P (BB_END (e->src)))
1547 rtx next = next_nonnote_insn (BB_END (e->src));
1549 after = BB_HEAD (e->dest);
1550 /* The first insn after the call may be a stack pop, skip it. */
1552 && keep_with_call_p (next))
1555 next = next_nonnote_insn (next);
1559 if (!before && !after)
1561 /* Figure out where to put these things. If the destination has
1562 one predecessor, insert there. Except for the exit block. */
1563 if (EDGE_COUNT (e->dest->preds) == 1 && e->dest != EXIT_BLOCK_PTR)
1567 /* Get the location correct wrt a code label, and "nice" wrt
1568 a basic block note, and before everything else. */
1571 tmp = NEXT_INSN (tmp);
1572 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1573 tmp = NEXT_INSN (tmp);
1576 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1577 tmp = NEXT_INSN (tmp);
1578 if (tmp == BB_HEAD (bb))
1581 after = PREV_INSN (tmp);
1583 after = get_last_insn ();
1586 /* If the source has one successor and the edge is not abnormal,
1587 insert there. Except for the entry block. */
1588 else if ((e->flags & EDGE_ABNORMAL) == 0
1589 && EDGE_COUNT (e->src->succs) == 1
1590 && e->src != ENTRY_BLOCK_PTR)
1594 /* It is possible to have a non-simple jump here. Consider a target
1595 where some forms of unconditional jumps clobber a register. This
1596 happens on the fr30 for example.
1598 We know this block has a single successor, so we can just emit
1599 the queued insns before the jump. */
1600 if (JUMP_P (BB_END (bb)))
1601 for (before = BB_END (bb);
1602 NOTE_P (PREV_INSN (before))
1603 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1604 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1608 /* We'd better be fallthru, or we've lost track of
1610 gcc_assert (e->flags & EDGE_FALLTHRU);
1612 after = BB_END (bb);
1615 /* Otherwise we must split the edge. */
1618 bb = split_edge (e);
1619 after = BB_END (bb);
1621 if (flag_reorder_blocks_and_partition
1622 && targetm.have_named_sections
1623 && e->src != ENTRY_BLOCK_PTR
1624 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1625 && !(e->flags & EDGE_CROSSING))
1627 rtx bb_note, new_note, cur_insn;
1630 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1631 cur_insn = NEXT_INSN (cur_insn))
1632 if (NOTE_P (cur_insn)
1633 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1639 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1641 NOTE_BASIC_BLOCK (new_note) = bb;
1642 if (JUMP_P (BB_END (bb))
1643 && !any_condjump_p (BB_END (bb))
1644 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
1645 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1646 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1647 if (after == bb_note)
1653 /* Now that we've found the spot, do the insertion. */
1657 emit_insn_before_noloc (insns, before);
1658 last = prev_nonnote_insn (before);
1661 last = emit_insn_after_noloc (insns, after);
1663 if (returnjump_p (last))
1665 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1666 This is not currently a problem because this only happens
1667 for the (single) epilogue, which already has a fallthru edge
1670 e = EDGE_SUCC (bb, 0);
1671 gcc_assert (e->dest == EXIT_BLOCK_PTR
1672 && EDGE_COUNT (bb->succs) == 1 && (e->flags & EDGE_FALLTHRU));
1674 e->flags &= ~EDGE_FALLTHRU;
1675 emit_barrier_after (last);
1678 delete_insn (before);
1681 gcc_assert (!JUMP_P (last));
1683 /* Mark the basic block for find_sub_basic_blocks. */
1687 /* Update the CFG for all queued instructions. */
1690 commit_edge_insertions (void)
1694 bool changed = false;
1696 #ifdef ENABLE_CHECKING
1697 verify_flow_info ();
1700 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1705 FOR_EACH_EDGE (e, ei, bb->succs)
1709 commit_one_edge_insertion (e, false);
1716 blocks = sbitmap_alloc (last_basic_block);
1717 sbitmap_zero (blocks);
1721 SET_BIT (blocks, bb->index);
1722 /* Check for forgotten bb->aux values before commit_edge_insertions
1724 gcc_assert (bb->aux == &bb->aux);
1727 find_many_sub_basic_blocks (blocks);
1728 sbitmap_free (blocks);
1731 /* Update the CFG for all queued instructions, taking special care of inserting
1732 code on edges between call and storing its return value. */
1735 commit_edge_insertions_watch_calls (void)
1739 bool changed = false;
1741 #ifdef ENABLE_CHECKING
1742 verify_flow_info ();
1745 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1750 FOR_EACH_EDGE (e, ei, bb->succs)
1754 commit_one_edge_insertion (e, true);
1761 blocks = sbitmap_alloc (last_basic_block);
1762 sbitmap_zero (blocks);
1766 SET_BIT (blocks, bb->index);
1767 /* Check for forgotten bb->aux values before commit_edge_insertions
1769 gcc_assert (bb->aux == &bb->aux);
1772 find_many_sub_basic_blocks (blocks);
1773 sbitmap_free (blocks);
1776 /* Print out RTL-specific basic block information (live information
1777 at start and end). */
1780 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1786 s_indent = alloca ((size_t) indent + 1);
1787 memset (s_indent, ' ', (size_t) indent);
1788 s_indent[indent] = '\0';
1790 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1791 dump_regset (bb->global_live_at_start, outf);
1794 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1795 insn = NEXT_INSN (insn))
1796 print_rtl_single (outf, insn);
1798 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1799 dump_regset (bb->global_live_at_end, outf);
1803 /* Like print_rtl, but also print out live information for the start of each
1807 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1812 fprintf (outf, "(nil)\n");
1815 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1816 int max_uid = get_max_uid ();
1817 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1818 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1819 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1823 FOR_EACH_BB_REVERSE (bb)
1827 start[INSN_UID (BB_HEAD (bb))] = bb;
1828 end[INSN_UID (BB_END (bb))] = bb;
1829 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1831 enum bb_state state = IN_MULTIPLE_BB;
1833 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1835 in_bb_p[INSN_UID (x)] = state;
1837 if (x == BB_END (bb))
1842 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1846 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1848 fprintf (outf, ";; Start of basic block %d, registers live:",
1850 dump_regset (bb->global_live_at_start, outf);
1854 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1855 && !NOTE_P (tmp_rtx)
1856 && !BARRIER_P (tmp_rtx))
1857 fprintf (outf, ";; Insn is not within a basic block\n");
1858 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1859 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1861 did_output = print_rtl_single (outf, tmp_rtx);
1863 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1865 fprintf (outf, ";; End of basic block %d, registers live:\n",
1867 dump_regset (bb->global_live_at_end, outf);
1880 if (current_function_epilogue_delay_list != 0)
1882 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1883 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1884 tmp_rtx = XEXP (tmp_rtx, 1))
1885 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1890 update_br_prob_note (basic_block bb)
1893 if (!JUMP_P (BB_END (bb)))
1895 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1896 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1898 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1901 /* Verify the CFG and RTL consistency common for both underlying RTL and
1904 Currently it does following checks:
1906 - test head/end pointers
1907 - overlapping of basic blocks
1908 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1909 - tails of basic blocks (ensure that boundary is necessary)
1910 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1911 and NOTE_INSN_BASIC_BLOCK
1912 - verify that no fall_thru edge crosses hot/cold partition boundaries
1914 In future it can be extended check a lot of other stuff as well
1915 (reachability of basic blocks, life information, etc. etc.). */
1918 rtl_verify_flow_info_1 (void)
1920 const int max_uid = get_max_uid ();
1921 rtx last_head = get_last_insn ();
1922 basic_block *bb_info;
1925 basic_block bb, last_bb_seen;
1927 bb_info = xcalloc (max_uid, sizeof (basic_block));
1929 /* Check bb chain & numbers. */
1930 last_bb_seen = ENTRY_BLOCK_PTR;
1932 FOR_EACH_BB_REVERSE (bb)
1934 rtx head = BB_HEAD (bb);
1935 rtx end = BB_END (bb);
1937 /* Verify the end of the basic block is in the INSN chain. */
1938 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1944 error ("end insn %d for block %d not found in the insn stream",
1945 INSN_UID (end), bb->index);
1949 /* Work backwards from the end to the head of the basic block
1950 to verify the head is in the RTL chain. */
1951 for (; x != NULL_RTX; x = PREV_INSN (x))
1953 /* While walking over the insn chain, verify insns appear
1954 in only one basic block and initialize the BB_INFO array
1955 used by other passes. */
1956 if (bb_info[INSN_UID (x)] != NULL)
1958 error ("insn %d is in multiple basic blocks (%d and %d)",
1959 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1963 bb_info[INSN_UID (x)] = bb;
1970 error ("head insn %d for block %d not found in the insn stream",
1971 INSN_UID (head), bb->index);
1978 /* Now check the basic blocks (boundaries etc.) */
1979 FOR_EACH_BB_REVERSE (bb)
1981 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1982 edge e, fallthru = NULL;
1986 if (INSN_P (BB_END (bb))
1987 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1988 && EDGE_COUNT (bb->succs) >= 2
1989 && any_condjump_p (BB_END (bb)))
1991 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1992 && profile_status != PROFILE_ABSENT)
1994 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1995 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1999 FOR_EACH_EDGE (e, ei, bb->succs)
2001 if (e->flags & EDGE_FALLTHRU)
2003 n_fallthru++, fallthru = e;
2004 if ((e->flags & EDGE_CROSSING)
2005 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
2006 && e->src != ENTRY_BLOCK_PTR
2007 && e->dest != EXIT_BLOCK_PTR))
2009 error ("Fallthru edge crosses section boundary (bb %i)",
2015 if ((e->flags & ~(EDGE_DFS_BACK
2017 | EDGE_IRREDUCIBLE_LOOP
2019 | EDGE_CROSSING)) == 0)
2022 if (e->flags & EDGE_ABNORMAL_CALL)
2025 if (e->flags & EDGE_EH)
2027 else if (e->flags & EDGE_ABNORMAL)
2031 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2032 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2034 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2038 && (!JUMP_P (BB_END (bb))
2039 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2040 || any_condjump_p (BB_END (bb))))))
2042 error ("Too many outgoing branch edges from bb %i", bb->index);
2045 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2047 error ("Fallthru edge after unconditional jump %i", bb->index);
2050 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2052 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2055 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2056 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2058 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2061 if (n_call && !CALL_P (BB_END (bb)))
2063 error ("Call edges for non-call insn in bb %i", bb->index);
2067 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2068 && (!JUMP_P (BB_END (bb))
2069 || any_condjump_p (BB_END (bb))
2070 || any_uncondjump_p (BB_END (bb))))
2072 error ("Abnormal edges for no purpose in bb %i", bb->index);
2076 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2077 /* We may have a barrier inside a basic block before dead code
2078 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2079 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2082 if (! BLOCK_FOR_INSN (x))
2084 ("insn %d inside basic block %d but block_for_insn is NULL",
2085 INSN_UID (x), bb->index);
2088 ("insn %d inside basic block %d but block_for_insn is %i",
2089 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2094 /* OK pointers are correct. Now check the header of basic
2095 block. It ought to contain optional CODE_LABEL followed
2096 by NOTE_BASIC_BLOCK. */
2100 if (BB_END (bb) == x)
2102 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2110 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2112 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2117 if (BB_END (bb) == x)
2118 /* Do checks for empty blocks her. e */
2121 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2123 if (NOTE_INSN_BASIC_BLOCK_P (x))
2125 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2126 INSN_UID (x), bb->index);
2130 if (x == BB_END (bb))
2133 if (control_flow_insn_p (x))
2135 error ("in basic block %d:", bb->index);
2136 fatal_insn ("flow control insn inside a basic block", x);
2146 /* Verify the CFG and RTL consistency common for both underlying RTL and
2149 Currently it does following checks:
2150 - all checks of rtl_verify_flow_info_1
2151 - check that all insns are in the basic blocks
2152 (except the switch handling code, barriers and notes)
2153 - check that all returns are followed by barriers
2154 - check that all fallthru edge points to the adjacent blocks. */
2156 rtl_verify_flow_info (void)
2159 int err = rtl_verify_flow_info_1 ();
2162 const rtx rtx_first = get_insns ();
2163 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2165 FOR_EACH_BB_REVERSE (bb)
2170 FOR_EACH_EDGE (e, ei, bb->succs)
2171 if (e->flags & EDGE_FALLTHRU)
2177 /* Ensure existence of barrier in BB with no fallthru edges. */
2178 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2179 insn = NEXT_INSN (insn))
2182 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2184 error ("missing barrier after block %i", bb->index);
2189 else if (e->src != ENTRY_BLOCK_PTR
2190 && e->dest != EXIT_BLOCK_PTR)
2194 if (e->src->next_bb != e->dest)
2197 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2198 e->src->index, e->dest->index);
2202 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2203 insn = NEXT_INSN (insn))
2204 if (BARRIER_P (insn)
2205 #ifndef CASE_DROPS_THROUGH
2208 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2212 error ("verify_flow_info: Incorrect fallthru %i->%i",
2213 e->src->index, e->dest->index);
2214 fatal_insn ("wrong insn in the fallthru edge", insn);
2221 last_bb_seen = ENTRY_BLOCK_PTR;
2223 for (x = rtx_first; x; x = NEXT_INSN (x))
2225 if (NOTE_INSN_BASIC_BLOCK_P (x))
2227 bb = NOTE_BASIC_BLOCK (x);
2230 if (bb != last_bb_seen->next_bb)
2231 internal_error ("basic blocks not laid down consecutively");
2233 curr_bb = last_bb_seen = bb;
2238 switch (GET_CODE (x))
2245 /* An addr_vec is placed outside any basic block. */
2247 && JUMP_P (NEXT_INSN (x))
2248 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2249 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2252 /* But in any case, non-deletable labels can appear anywhere. */
2256 fatal_insn ("insn outside basic block", x);
2262 && returnjump_p (x) && ! condjump_p (x)
2263 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2264 fatal_insn ("return not followed by barrier", x);
2265 if (curr_bb && x == BB_END (curr_bb))
2269 if (num_bb_notes != n_basic_blocks)
2271 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2272 num_bb_notes, n_basic_blocks);
2277 /* Assume that the preceding pass has possibly eliminated jump instructions
2278 or converted the unconditional jumps. Eliminate the edges from CFG.
2279 Return true if any edges are eliminated. */
2282 purge_dead_edges (basic_block bb)
2285 rtx insn = BB_END (bb), note;
2286 bool purged = false;
2290 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2291 if (NONJUMP_INSN_P (insn)
2292 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2296 if (! may_trap_p (PATTERN (insn))
2297 || ((eqnote = find_reg_equal_equiv_note (insn))
2298 && ! may_trap_p (XEXP (eqnote, 0))))
2299 remove_note (insn, note);
2302 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2303 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2305 if (e->flags & EDGE_EH)
2307 if (can_throw_internal (BB_END (bb)))
2313 else if (e->flags & EDGE_ABNORMAL_CALL)
2315 if (CALL_P (BB_END (bb))
2316 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2317 || INTVAL (XEXP (note, 0)) >= 0))
2330 bb->flags |= BB_DIRTY;
2340 /* We do care only about conditional jumps and simplejumps. */
2341 if (!any_condjump_p (insn)
2342 && !returnjump_p (insn)
2343 && !simplejump_p (insn))
2346 /* Branch probability/prediction notes are defined only for
2347 condjumps. We've possibly turned condjump into simplejump. */
2348 if (simplejump_p (insn))
2350 note = find_reg_note (insn, REG_BR_PROB, NULL);
2352 remove_note (insn, note);
2353 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2354 remove_note (insn, note);
2357 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2359 /* Avoid abnormal flags to leak from computed jumps turned
2360 into simplejumps. */
2362 e->flags &= ~EDGE_ABNORMAL;
2364 /* See if this edge is one we should keep. */
2365 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2366 /* A conditional jump can fall through into the next
2367 block, so we should keep the edge. */
2372 else if (e->dest != EXIT_BLOCK_PTR
2373 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2374 /* If the destination block is the target of the jump,
2380 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2381 /* If the destination block is the exit block, and this
2382 instruction is a return, then keep the edge. */
2387 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2388 /* Keep the edges that correspond to exceptions thrown by
2389 this instruction and rematerialize the EDGE_ABNORMAL
2390 flag we just cleared above. */
2392 e->flags |= EDGE_ABNORMAL;
2397 /* We do not need this edge. */
2398 bb->flags |= BB_DIRTY;
2403 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2407 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2412 /* Redistribute probabilities. */
2413 if (EDGE_COUNT (bb->succs) == 1)
2415 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2416 EDGE_SUCC (bb, 0)->count = bb->count;
2420 note = find_reg_note (insn, REG_BR_PROB, NULL);
2424 b = BRANCH_EDGE (bb);
2425 f = FALLTHRU_EDGE (bb);
2426 b->probability = INTVAL (XEXP (note, 0));
2427 f->probability = REG_BR_PROB_BASE - b->probability;
2428 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2429 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2434 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2436 /* First, there should not be any EH or ABCALL edges resulting
2437 from non-local gotos and the like. If there were, we shouldn't
2438 have created the sibcall in the first place. Second, there
2439 should of course never have been a fallthru edge. */
2440 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2441 gcc_assert (EDGE_SUCC (bb, 0)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2446 /* If we don't see a jump insn, we don't know exactly why the block would
2447 have been broken at this point. Look for a simple, non-fallthru edge,
2448 as these are only created by conditional branches. If we find such an
2449 edge we know that there used to be a jump here and can then safely
2450 remove all non-fallthru edges. */
2452 FOR_EACH_EDGE (e, ei, bb->succs)
2453 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2462 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2464 if (!(e->flags & EDGE_FALLTHRU))
2466 bb->flags |= BB_DIRTY;
2474 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2476 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2477 EDGE_SUCC (bb, 0)->count = bb->count;
2480 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2485 /* Search all basic blocks for potentially dead edges and purge them. Return
2486 true if some edge has been eliminated. */
2489 purge_all_dead_edges (int update_life_p)
2497 blocks = sbitmap_alloc (last_basic_block);
2498 sbitmap_zero (blocks);
2503 bool purged_here = purge_dead_edges (bb);
2505 purged |= purged_here;
2506 if (purged_here && update_life_p)
2507 SET_BIT (blocks, bb->index);
2510 if (update_life_p && purged)
2511 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2512 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2513 | PROP_KILL_DEAD_CODE);
2516 sbitmap_free (blocks);
2520 /* Same as split_block but update cfg_layout structures. */
2523 cfg_layout_split_block (basic_block bb, void *insnp)
2526 basic_block new_bb = rtl_split_block (bb, insn);
2528 new_bb->rbi->footer = bb->rbi->footer;
2529 bb->rbi->footer = NULL;
2535 /* Redirect Edge to DEST. */
2537 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2539 basic_block src = e->src;
2542 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2545 if (e->dest == dest)
2548 if (e->src != ENTRY_BLOCK_PTR
2549 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2551 src->flags |= BB_DIRTY;
2555 if (e->src == ENTRY_BLOCK_PTR
2556 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2559 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2560 e->src->index, dest->index);
2562 e->src->flags |= BB_DIRTY;
2563 redirect_edge_succ (e, dest);
2567 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2568 in the case the basic block appears to be in sequence. Avoid this
2571 if (e->flags & EDGE_FALLTHRU)
2573 /* Redirect any branch edges unified with the fallthru one. */
2574 if (JUMP_P (BB_END (src))
2575 && label_is_jump_target_p (BB_HEAD (e->dest),
2581 fprintf (dump_file, "Fallthru edge unified with branch "
2582 "%i->%i redirected to %i\n",
2583 e->src->index, e->dest->index, dest->index);
2584 e->flags &= ~EDGE_FALLTHRU;
2585 redirected = redirect_branch_edge (e, dest);
2586 gcc_assert (redirected);
2587 e->flags |= EDGE_FALLTHRU;
2588 e->src->flags |= BB_DIRTY;
2591 /* In case we are redirecting fallthru edge to the branch edge
2592 of conditional jump, remove it. */
2593 if (EDGE_COUNT (src->succs) == 2)
2600 FOR_EACH_EDGE (tmp, ei, src->succs)
2610 if (EDGE_COUNT (src->succs) > (ix + 1))
2611 s = EDGE_SUCC (src, ix + 1);
2613 s = EDGE_SUCC (src, 0);
2616 && any_condjump_p (BB_END (src))
2617 && onlyjump_p (BB_END (src)))
2618 delete_insn (BB_END (src));
2620 ret = redirect_edge_succ_nodup (e, dest);
2622 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2623 e->src->index, e->dest->index, dest->index);
2626 ret = redirect_branch_edge (e, dest);
2628 /* We don't want simplejumps in the insn stream during cfglayout. */
2629 gcc_assert (!simplejump_p (BB_END (src)));
2631 src->flags |= BB_DIRTY;
2635 /* Simple wrapper as we always can redirect fallthru edges. */
2637 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2639 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2641 gcc_assert (redirected);
2645 /* Same as delete_basic_block but update cfg_layout structures. */
2648 cfg_layout_delete_block (basic_block bb)
2650 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2652 if (bb->rbi->header)
2654 next = BB_HEAD (bb);
2656 NEXT_INSN (prev) = bb->rbi->header;
2658 set_first_insn (bb->rbi->header);
2659 PREV_INSN (bb->rbi->header) = prev;
2660 insn = bb->rbi->header;
2661 while (NEXT_INSN (insn))
2662 insn = NEXT_INSN (insn);
2663 NEXT_INSN (insn) = next;
2664 PREV_INSN (next) = insn;
2666 next = NEXT_INSN (BB_END (bb));
2667 if (bb->rbi->footer)
2669 insn = bb->rbi->footer;
2672 if (BARRIER_P (insn))
2674 if (PREV_INSN (insn))
2675 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2677 bb->rbi->footer = NEXT_INSN (insn);
2678 if (NEXT_INSN (insn))
2679 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2683 insn = NEXT_INSN (insn);
2685 if (bb->rbi->footer)
2688 NEXT_INSN (insn) = bb->rbi->footer;
2689 PREV_INSN (bb->rbi->footer) = insn;
2690 while (NEXT_INSN (insn))
2691 insn = NEXT_INSN (insn);
2692 NEXT_INSN (insn) = next;
2694 PREV_INSN (next) = insn;
2696 set_last_insn (insn);
2699 if (bb->next_bb != EXIT_BLOCK_PTR)
2700 to = &bb->next_bb->rbi->header;
2702 to = &cfg_layout_function_footer;
2703 rtl_delete_block (bb);
2706 prev = NEXT_INSN (prev);
2708 prev = get_insns ();
2710 next = PREV_INSN (next);
2712 next = get_last_insn ();
2714 if (next && NEXT_INSN (next) != prev)
2716 remaints = unlink_insn_chain (prev, next);
2718 while (NEXT_INSN (insn))
2719 insn = NEXT_INSN (insn);
2720 NEXT_INSN (insn) = *to;
2722 PREV_INSN (*to) = insn;
2727 /* Return true when blocks A and B can be safely merged. */
2729 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2731 /* If we are partitioning hot/cold basic blocks, we don't want to
2732 mess up unconditional or indirect jumps that cross between hot
2735 Basic block partitioning may result in some jumps that appear to
2736 be optimizable (or blocks that appear to be mergeable), but which really
2737 must be left untouched (they are required to make it safely across
2738 partition boundaries). See the comments at the top of
2739 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2741 if (flag_reorder_blocks_and_partition
2742 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2743 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2744 || BB_PARTITION (a) != BB_PARTITION (b)))
2747 /* There must be exactly one edge in between the blocks. */
2748 return (EDGE_COUNT (a->succs) == 1
2749 && EDGE_SUCC (a, 0)->dest == b
2750 && EDGE_COUNT (b->preds) == 1
2752 /* Must be simple edge. */
2753 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
2754 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2755 /* If the jump insn has side effects,
2756 we can't kill the edge. */
2757 && (!JUMP_P (BB_END (a))
2758 || (reload_completed
2759 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2762 /* Merge block A and B, abort when it is not possible. */
2764 cfg_layout_merge_blocks (basic_block a, basic_block b)
2766 #ifdef ENABLE_CHECKING
2767 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2770 /* If there was a CODE_LABEL beginning B, delete it. */
2771 if (LABEL_P (BB_HEAD (b)))
2772 delete_insn (BB_HEAD (b));
2774 /* We should have fallthru edge in a, or we can do dummy redirection to get
2776 if (JUMP_P (BB_END (a)))
2777 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2778 gcc_assert (!JUMP_P (BB_END (a)));
2780 /* Possible line number notes should appear in between. */
2783 rtx first = BB_END (a), last;
2785 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2786 delete_insn_chain (NEXT_INSN (first), last);
2787 b->rbi->header = NULL;
2790 /* In the case basic blocks are not adjacent, move them around. */
2791 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2793 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2795 emit_insn_after_noloc (first, BB_END (a));
2796 /* Skip possible DELETED_LABEL insn. */
2797 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2798 first = NEXT_INSN (first);
2799 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2801 delete_insn (first);
2803 /* Otherwise just re-associate the instructions. */
2808 for (insn = BB_HEAD (b);
2809 insn != NEXT_INSN (BB_END (b));
2810 insn = NEXT_INSN (insn))
2811 set_block_for_insn (insn, a);
2813 /* Skip possible DELETED_LABEL insn. */
2814 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2815 insn = NEXT_INSN (insn);
2816 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2818 BB_END (a) = BB_END (b);
2822 /* Possible tablejumps and barriers should appear after the block. */
2825 if (!a->rbi->footer)
2826 a->rbi->footer = b->rbi->footer;
2829 rtx last = a->rbi->footer;
2831 while (NEXT_INSN (last))
2832 last = NEXT_INSN (last);
2833 NEXT_INSN (last) = b->rbi->footer;
2834 PREV_INSN (b->rbi->footer) = last;
2836 b->rbi->footer = NULL;
2840 fprintf (dump_file, "Merged blocks %d and %d.\n",
2841 a->index, b->index);
2847 cfg_layout_split_edge (edge e)
2850 basic_block new_bb =
2851 create_basic_block (e->src != ENTRY_BLOCK_PTR
2852 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2855 /* ??? This info is likely going to be out of date very soon, but we must
2856 create it to avoid getting an ICE later. */
2857 if (e->dest->global_live_at_start)
2859 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2860 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2861 COPY_REG_SET (new_bb->global_live_at_start,
2862 e->dest->global_live_at_start);
2863 COPY_REG_SET (new_bb->global_live_at_end,
2864 e->dest->global_live_at_start);
2867 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2868 redirect_edge_and_branch_force (e, new_bb);
2873 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2876 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2880 /* Return 1 if BB ends with a call, possibly followed by some
2881 instructions that must stay with the call, 0 otherwise. */
2884 rtl_block_ends_with_call_p (basic_block bb)
2886 rtx insn = BB_END (bb);
2888 while (!CALL_P (insn)
2889 && insn != BB_HEAD (bb)
2890 && keep_with_call_p (insn))
2891 insn = PREV_INSN (insn);
2892 return (CALL_P (insn));
2895 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2898 rtl_block_ends_with_condjump_p (basic_block bb)
2900 return any_condjump_p (BB_END (bb));
2903 /* Return true if we need to add fake edge to exit.
2904 Helper function for rtl_flow_call_edges_add. */
2907 need_fake_edge_p (rtx insn)
2913 && !SIBLING_CALL_P (insn)
2914 && !find_reg_note (insn, REG_NORETURN, NULL)
2915 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2916 && !CONST_OR_PURE_CALL_P (insn)))
2919 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2920 && MEM_VOLATILE_P (PATTERN (insn)))
2921 || (GET_CODE (PATTERN (insn)) == PARALLEL
2922 && asm_noperands (insn) != -1
2923 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2924 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2927 /* Add fake edges to the function exit for any non constant and non noreturn
2928 calls, volatile inline assembly in the bitmap of blocks specified by
2929 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2932 The goal is to expose cases in which entering a basic block does not imply
2933 that all subsequent instructions must be executed. */
2936 rtl_flow_call_edges_add (sbitmap blocks)
2939 int blocks_split = 0;
2940 int last_bb = last_basic_block;
2941 bool check_last_block = false;
2943 if (n_basic_blocks == 0)
2947 check_last_block = true;
2949 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2951 /* In the last basic block, before epilogue generation, there will be
2952 a fallthru edge to EXIT. Special care is required if the last insn
2953 of the last basic block is a call because make_edge folds duplicate
2954 edges, which would result in the fallthru edge also being marked
2955 fake, which would result in the fallthru edge being removed by
2956 remove_fake_edges, which would result in an invalid CFG.
2958 Moreover, we can't elide the outgoing fake edge, since the block
2959 profiler needs to take this into account in order to solve the minimal
2960 spanning tree in the case that the call doesn't return.
2962 Handle this by adding a dummy instruction in a new last basic block. */
2963 if (check_last_block)
2965 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2966 rtx insn = BB_END (bb);
2968 /* Back up past insns that must be kept in the same block as a call. */
2969 while (insn != BB_HEAD (bb)
2970 && keep_with_call_p (insn))
2971 insn = PREV_INSN (insn);
2973 if (need_fake_edge_p (insn))
2978 FOR_EACH_EDGE (e, ei, bb->succs)
2979 if (e->dest == EXIT_BLOCK_PTR)
2981 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2982 commit_edge_insertions ();
2988 /* Now add fake edges to the function exit for any non constant
2989 calls since there is no way that we can determine if they will
2992 for (i = 0; i < last_bb; i++)
2994 basic_block bb = BASIC_BLOCK (i);
3001 if (blocks && !TEST_BIT (blocks, i))
3004 for (insn = BB_END (bb); ; insn = prev_insn)
3006 prev_insn = PREV_INSN (insn);
3007 if (need_fake_edge_p (insn))
3010 rtx split_at_insn = insn;
3012 /* Don't split the block between a call and an insn that should
3013 remain in the same block as the call. */
3015 while (split_at_insn != BB_END (bb)
3016 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3017 split_at_insn = NEXT_INSN (split_at_insn);
3019 /* The handling above of the final block before the epilogue
3020 should be enough to verify that there is no edge to the exit
3021 block in CFG already. Calling make_edge in such case would
3022 cause us to mark that edge as fake and remove it later. */
3024 #ifdef ENABLE_CHECKING
3025 if (split_at_insn == BB_END (bb))
3028 FOR_EACH_EDGE (e, ei, bb->succs)
3029 gcc_assert (e->dest != EXIT_BLOCK_PTR);
3033 /* Note that the following may create a new basic block
3034 and renumber the existing basic blocks. */
3035 if (split_at_insn != BB_END (bb))
3037 e = split_block (bb, split_at_insn);
3042 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3045 if (insn == BB_HEAD (bb))
3051 verify_flow_info ();
3053 return blocks_split;
3056 /* Implementation of CFG manipulation for linearized RTL. */
3057 struct cfg_hooks rtl_cfg_hooks = {
3059 rtl_verify_flow_info,
3061 rtl_create_basic_block,
3062 rtl_redirect_edge_and_branch,
3063 rtl_redirect_edge_and_branch_force,
3066 rtl_move_block_after,
3067 rtl_can_merge_blocks, /* can_merge_blocks_p */
3071 NULL, /* can_duplicate_block_p */
3072 NULL, /* duplicate_block */
3074 rtl_make_forwarder_block,
3075 rtl_tidy_fallthru_edge,
3076 rtl_block_ends_with_call_p,
3077 rtl_block_ends_with_condjump_p,
3078 rtl_flow_call_edges_add
3081 /* Implementation of CFG manipulation for cfg layout RTL, where
3082 basic block connected via fallthru edges does not have to be adjacent.
3083 This representation will hopefully become the default one in future
3084 version of the compiler. */
3086 /* We do not want to declare these functions in a header file, since they
3087 should only be used through the cfghooks interface, and we do not want to
3088 move them here since it would require also moving quite a lot of related
3090 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3091 extern basic_block cfg_layout_duplicate_bb (basic_block);
3093 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3095 rtl_verify_flow_info_1,
3097 cfg_layout_create_basic_block,
3098 cfg_layout_redirect_edge_and_branch,
3099 cfg_layout_redirect_edge_and_branch_force,
3100 cfg_layout_delete_block,
3101 cfg_layout_split_block,
3102 rtl_move_block_after,
3103 cfg_layout_can_merge_blocks_p,
3104 cfg_layout_merge_blocks,
3107 cfg_layout_can_duplicate_bb_p,
3108 cfg_layout_duplicate_bb,
3109 cfg_layout_split_edge,
3110 rtl_make_forwarder_block,
3112 rtl_block_ends_with_call_p,
3113 rtl_block_ends_with_condjump_p,
3114 rtl_flow_call_edges_add