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;
1469 #ifdef AVOID_CCMODE_COPIES
1475 for (x = insn; x; x = NEXT_INSN (x))
1477 note_stores (PATTERN (x), mark_killed_regs, killed);
1478 bitmap_operation (killed, killed, e->dest->global_live_at_start,
1481 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno,
1483 mode = regno < FIRST_PSEUDO_REGISTER
1484 ? reg_raw_mode[regno]
1485 : GET_MODE (regno_reg_rtx[regno]);
1486 if (mode == VOIDmode)
1489 if (noccmode && mode == CCmode)
1492 save_regs = alloc_EXPR_LIST (0,
1495 gen_raw_REG (mode, regno)),
1504 for (x = save_regs; x; x = XEXP (x, 1))
1506 from = XEXP (XEXP (x, 0), 1);
1507 to = XEXP (XEXP (x, 0), 0);
1508 emit_move_insn (to, from);
1511 for (x = save_regs; x; x = XEXP (x, 1))
1513 from = XEXP (XEXP (x, 0), 0);
1514 to = XEXP (XEXP (x, 0), 1);
1515 emit_move_insn (to, from);
1517 insn = get_insns ();
1519 free_EXPR_LIST_list (&save_regs);
1521 insert_insn_on_edge (insn, e);
1523 FREE_REG_SET (killed);
1527 /* Update the CFG for the instructions queued on edge E. */
1530 commit_one_edge_insertion (edge e, int watch_calls)
1532 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1533 basic_block bb = NULL;
1535 /* Pull the insns off the edge now since the edge might go away. */
1537 e->insns.r = NULL_RTX;
1539 /* Special case -- avoid inserting code between call and storing
1540 its return value. */
1541 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1542 && EDGE_COUNT (e->dest->preds) == 1
1543 && e->src != ENTRY_BLOCK_PTR
1544 && CALL_P (BB_END (e->src)))
1546 rtx next = next_nonnote_insn (BB_END (e->src));
1548 after = BB_HEAD (e->dest);
1549 /* The first insn after the call may be a stack pop, skip it. */
1551 && keep_with_call_p (next))
1554 next = next_nonnote_insn (next);
1558 if (!before && !after)
1560 /* Figure out where to put these things. If the destination has
1561 one predecessor, insert there. Except for the exit block. */
1562 if (EDGE_COUNT (e->dest->preds) == 1 && e->dest != EXIT_BLOCK_PTR)
1566 /* Get the location correct wrt a code label, and "nice" wrt
1567 a basic block note, and before everything else. */
1570 tmp = NEXT_INSN (tmp);
1571 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1572 tmp = NEXT_INSN (tmp);
1575 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1576 tmp = NEXT_INSN (tmp);
1577 if (tmp == BB_HEAD (bb))
1580 after = PREV_INSN (tmp);
1582 after = get_last_insn ();
1585 /* If the source has one successor and the edge is not abnormal,
1586 insert there. Except for the entry block. */
1587 else if ((e->flags & EDGE_ABNORMAL) == 0
1588 && EDGE_COUNT (e->src->succs) == 1
1589 && e->src != ENTRY_BLOCK_PTR)
1593 /* It is possible to have a non-simple jump here. Consider a target
1594 where some forms of unconditional jumps clobber a register. This
1595 happens on the fr30 for example.
1597 We know this block has a single successor, so we can just emit
1598 the queued insns before the jump. */
1599 if (JUMP_P (BB_END (bb)))
1600 for (before = BB_END (bb);
1601 NOTE_P (PREV_INSN (before))
1602 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1603 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1607 /* We'd better be fallthru, or we've lost track of
1609 gcc_assert (e->flags & EDGE_FALLTHRU);
1611 after = BB_END (bb);
1614 /* Otherwise we must split the edge. */
1617 bb = split_edge (e);
1618 after = BB_END (bb);
1620 if (flag_reorder_blocks_and_partition
1621 && targetm.have_named_sections
1622 && e->src != ENTRY_BLOCK_PTR
1623 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1624 && !(e->flags & EDGE_CROSSING))
1626 rtx bb_note, new_note, cur_insn;
1629 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1630 cur_insn = NEXT_INSN (cur_insn))
1631 if (NOTE_P (cur_insn)
1632 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1638 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1640 NOTE_BASIC_BLOCK (new_note) = bb;
1641 if (JUMP_P (BB_END (bb))
1642 && !any_condjump_p (BB_END (bb))
1643 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
1644 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1645 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1646 if (after == bb_note)
1652 /* Now that we've found the spot, do the insertion. */
1656 emit_insn_before_noloc (insns, before);
1657 last = prev_nonnote_insn (before);
1660 last = emit_insn_after_noloc (insns, after);
1662 if (returnjump_p (last))
1664 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1665 This is not currently a problem because this only happens
1666 for the (single) epilogue, which already has a fallthru edge
1669 e = EDGE_SUCC (bb, 0);
1670 gcc_assert (e->dest == EXIT_BLOCK_PTR
1671 && EDGE_COUNT (bb->succs) == 1 && (e->flags & EDGE_FALLTHRU));
1673 e->flags &= ~EDGE_FALLTHRU;
1674 emit_barrier_after (last);
1677 delete_insn (before);
1680 gcc_assert (!JUMP_P (last));
1682 /* Mark the basic block for find_sub_basic_blocks. */
1686 /* Update the CFG for all queued instructions. */
1689 commit_edge_insertions (void)
1693 bool changed = false;
1695 #ifdef ENABLE_CHECKING
1696 verify_flow_info ();
1699 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1704 FOR_EACH_EDGE (e, ei, bb->succs)
1708 commit_one_edge_insertion (e, false);
1715 blocks = sbitmap_alloc (last_basic_block);
1716 sbitmap_zero (blocks);
1720 SET_BIT (blocks, bb->index);
1721 /* Check for forgotten bb->aux values before commit_edge_insertions
1723 gcc_assert (bb->aux == &bb->aux);
1726 find_many_sub_basic_blocks (blocks);
1727 sbitmap_free (blocks);
1730 /* Update the CFG for all queued instructions, taking special care of inserting
1731 code on edges between call and storing its return value. */
1734 commit_edge_insertions_watch_calls (void)
1738 bool changed = false;
1740 #ifdef ENABLE_CHECKING
1741 verify_flow_info ();
1744 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1749 FOR_EACH_EDGE (e, ei, bb->succs)
1753 commit_one_edge_insertion (e, true);
1760 blocks = sbitmap_alloc (last_basic_block);
1761 sbitmap_zero (blocks);
1765 SET_BIT (blocks, bb->index);
1766 /* Check for forgotten bb->aux values before commit_edge_insertions
1768 gcc_assert (bb->aux == &bb->aux);
1771 find_many_sub_basic_blocks (blocks);
1772 sbitmap_free (blocks);
1775 /* Print out RTL-specific basic block information (live information
1776 at start and end). */
1779 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1785 s_indent = alloca ((size_t) indent + 1);
1786 memset (s_indent, ' ', (size_t) indent);
1787 s_indent[indent] = '\0';
1789 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1790 dump_regset (bb->global_live_at_start, outf);
1793 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1794 insn = NEXT_INSN (insn))
1795 print_rtl_single (outf, insn);
1797 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1798 dump_regset (bb->global_live_at_end, outf);
1802 /* Like print_rtl, but also print out live information for the start of each
1806 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1811 fprintf (outf, "(nil)\n");
1814 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1815 int max_uid = get_max_uid ();
1816 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1817 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1818 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1822 FOR_EACH_BB_REVERSE (bb)
1826 start[INSN_UID (BB_HEAD (bb))] = bb;
1827 end[INSN_UID (BB_END (bb))] = bb;
1828 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1830 enum bb_state state = IN_MULTIPLE_BB;
1832 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1834 in_bb_p[INSN_UID (x)] = state;
1836 if (x == BB_END (bb))
1841 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1845 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1847 fprintf (outf, ";; Start of basic block %d, registers live:",
1849 dump_regset (bb->global_live_at_start, outf);
1853 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1854 && !NOTE_P (tmp_rtx)
1855 && !BARRIER_P (tmp_rtx))
1856 fprintf (outf, ";; Insn is not within a basic block\n");
1857 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1858 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1860 did_output = print_rtl_single (outf, tmp_rtx);
1862 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1864 fprintf (outf, ";; End of basic block %d, registers live:\n",
1866 dump_regset (bb->global_live_at_end, outf);
1879 if (current_function_epilogue_delay_list != 0)
1881 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1882 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1883 tmp_rtx = XEXP (tmp_rtx, 1))
1884 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1889 update_br_prob_note (basic_block bb)
1892 if (!JUMP_P (BB_END (bb)))
1894 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1895 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1897 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1900 /* Verify the CFG and RTL consistency common for both underlying RTL and
1903 Currently it does following checks:
1905 - test head/end pointers
1906 - overlapping of basic blocks
1907 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1908 - tails of basic blocks (ensure that boundary is necessary)
1909 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1910 and NOTE_INSN_BASIC_BLOCK
1911 - verify that no fall_thru edge crosses hot/cold partition boundaries
1913 In future it can be extended check a lot of other stuff as well
1914 (reachability of basic blocks, life information, etc. etc.). */
1917 rtl_verify_flow_info_1 (void)
1919 const int max_uid = get_max_uid ();
1920 rtx last_head = get_last_insn ();
1921 basic_block *bb_info;
1924 basic_block bb, last_bb_seen;
1926 bb_info = xcalloc (max_uid, sizeof (basic_block));
1928 /* Check bb chain & numbers. */
1929 last_bb_seen = ENTRY_BLOCK_PTR;
1931 FOR_EACH_BB_REVERSE (bb)
1933 rtx head = BB_HEAD (bb);
1934 rtx end = BB_END (bb);
1936 /* Verify the end of the basic block is in the INSN chain. */
1937 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1943 error ("end insn %d for block %d not found in the insn stream",
1944 INSN_UID (end), bb->index);
1948 /* Work backwards from the end to the head of the basic block
1949 to verify the head is in the RTL chain. */
1950 for (; x != NULL_RTX; x = PREV_INSN (x))
1952 /* While walking over the insn chain, verify insns appear
1953 in only one basic block and initialize the BB_INFO array
1954 used by other passes. */
1955 if (bb_info[INSN_UID (x)] != NULL)
1957 error ("insn %d is in multiple basic blocks (%d and %d)",
1958 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1962 bb_info[INSN_UID (x)] = bb;
1969 error ("head insn %d for block %d not found in the insn stream",
1970 INSN_UID (head), bb->index);
1977 /* Now check the basic blocks (boundaries etc.) */
1978 FOR_EACH_BB_REVERSE (bb)
1980 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1981 edge e, fallthru = NULL;
1985 if (INSN_P (BB_END (bb))
1986 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1987 && EDGE_COUNT (bb->succs) >= 2
1988 && any_condjump_p (BB_END (bb)))
1990 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1991 && profile_status != PROFILE_ABSENT)
1993 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1994 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1998 FOR_EACH_EDGE (e, ei, bb->succs)
2000 if (e->flags & EDGE_FALLTHRU)
2002 n_fallthru++, fallthru = e;
2003 if ((e->flags & EDGE_CROSSING)
2004 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
2005 && e->src != ENTRY_BLOCK_PTR
2006 && e->dest != EXIT_BLOCK_PTR))
2008 error ("Fallthru edge crosses section boundary (bb %i)",
2014 if ((e->flags & ~(EDGE_DFS_BACK
2016 | EDGE_IRREDUCIBLE_LOOP
2018 | EDGE_CROSSING)) == 0)
2021 if (e->flags & EDGE_ABNORMAL_CALL)
2024 if (e->flags & EDGE_EH)
2026 else if (e->flags & EDGE_ABNORMAL)
2030 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2031 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2033 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2037 && (!JUMP_P (BB_END (bb))
2038 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2039 || any_condjump_p (BB_END (bb))))))
2041 error ("Too many outgoing branch edges from bb %i", bb->index);
2044 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2046 error ("Fallthru edge after unconditional jump %i", bb->index);
2049 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2051 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2054 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2055 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2057 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2060 if (n_call && !CALL_P (BB_END (bb)))
2062 error ("Call edges for non-call insn in bb %i", bb->index);
2066 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2067 && (!JUMP_P (BB_END (bb))
2068 || any_condjump_p (BB_END (bb))
2069 || any_uncondjump_p (BB_END (bb))))
2071 error ("Abnormal edges for no purpose in bb %i", bb->index);
2075 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2076 if (BLOCK_FOR_INSN (x) != bb)
2079 if (! BLOCK_FOR_INSN (x))
2081 ("insn %d inside basic block %d but block_for_insn is NULL",
2082 INSN_UID (x), bb->index);
2085 ("insn %d inside basic block %d but block_for_insn is %i",
2086 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2091 /* OK pointers are correct. Now check the header of basic
2092 block. It ought to contain optional CODE_LABEL followed
2093 by NOTE_BASIC_BLOCK. */
2097 if (BB_END (bb) == x)
2099 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2107 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2109 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2114 if (BB_END (bb) == x)
2115 /* Do checks for empty blocks her. e */
2118 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2120 if (NOTE_INSN_BASIC_BLOCK_P (x))
2122 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2123 INSN_UID (x), bb->index);
2127 if (x == BB_END (bb))
2130 if (control_flow_insn_p (x))
2132 error ("in basic block %d:", bb->index);
2133 fatal_insn ("flow control insn inside a basic block", x);
2143 /* Verify the CFG and RTL consistency common for both underlying RTL and
2146 Currently it does following checks:
2147 - all checks of rtl_verify_flow_info_1
2148 - check that all insns are in the basic blocks
2149 (except the switch handling code, barriers and notes)
2150 - check that all returns are followed by barriers
2151 - check that all fallthru edge points to the adjacent blocks. */
2153 rtl_verify_flow_info (void)
2156 int err = rtl_verify_flow_info_1 ();
2159 const rtx rtx_first = get_insns ();
2160 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2162 FOR_EACH_BB_REVERSE (bb)
2167 FOR_EACH_EDGE (e, ei, bb->succs)
2168 if (e->flags & EDGE_FALLTHRU)
2174 /* Ensure existence of barrier in BB with no fallthru edges. */
2175 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2176 insn = NEXT_INSN (insn))
2179 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2181 error ("missing barrier after block %i", bb->index);
2186 else if (e->src != ENTRY_BLOCK_PTR
2187 && e->dest != EXIT_BLOCK_PTR)
2191 if (e->src->next_bb != e->dest)
2194 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2195 e->src->index, e->dest->index);
2199 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2200 insn = NEXT_INSN (insn))
2201 if (BARRIER_P (insn)
2202 #ifndef CASE_DROPS_THROUGH
2205 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2209 error ("verify_flow_info: Incorrect fallthru %i->%i",
2210 e->src->index, e->dest->index);
2211 fatal_insn ("wrong insn in the fallthru edge", insn);
2218 last_bb_seen = ENTRY_BLOCK_PTR;
2220 for (x = rtx_first; x; x = NEXT_INSN (x))
2222 if (NOTE_INSN_BASIC_BLOCK_P (x))
2224 bb = NOTE_BASIC_BLOCK (x);
2227 if (bb != last_bb_seen->next_bb)
2228 internal_error ("basic blocks not laid down consecutively");
2230 curr_bb = last_bb_seen = bb;
2235 switch (GET_CODE (x))
2242 /* An addr_vec is placed outside any basic block. */
2244 && JUMP_P (NEXT_INSN (x))
2245 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2246 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2249 /* But in any case, non-deletable labels can appear anywhere. */
2253 fatal_insn ("insn outside basic block", x);
2259 && returnjump_p (x) && ! condjump_p (x)
2260 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2261 fatal_insn ("return not followed by barrier", x);
2262 if (curr_bb && x == BB_END (curr_bb))
2266 if (num_bb_notes != n_basic_blocks)
2268 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2269 num_bb_notes, n_basic_blocks);
2274 /* Assume that the preceding pass has possibly eliminated jump instructions
2275 or converted the unconditional jumps. Eliminate the edges from CFG.
2276 Return true if any edges are eliminated. */
2279 purge_dead_edges (basic_block bb)
2282 rtx insn = BB_END (bb), note;
2283 bool purged = false;
2287 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2288 if (NONJUMP_INSN_P (insn)
2289 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2293 if (! may_trap_p (PATTERN (insn))
2294 || ((eqnote = find_reg_equal_equiv_note (insn))
2295 && ! may_trap_p (XEXP (eqnote, 0))))
2296 remove_note (insn, note);
2299 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2300 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2302 if (e->flags & EDGE_EH)
2304 if (can_throw_internal (BB_END (bb)))
2310 else if (e->flags & EDGE_ABNORMAL_CALL)
2312 if (CALL_P (BB_END (bb))
2313 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2314 || INTVAL (XEXP (note, 0)) >= 0))
2327 bb->flags |= BB_DIRTY;
2337 /* We do care only about conditional jumps and simplejumps. */
2338 if (!any_condjump_p (insn)
2339 && !returnjump_p (insn)
2340 && !simplejump_p (insn))
2343 /* Branch probability/prediction notes are defined only for
2344 condjumps. We've possibly turned condjump into simplejump. */
2345 if (simplejump_p (insn))
2347 note = find_reg_note (insn, REG_BR_PROB, NULL);
2349 remove_note (insn, note);
2350 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2351 remove_note (insn, note);
2354 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2356 /* Avoid abnormal flags to leak from computed jumps turned
2357 into simplejumps. */
2359 e->flags &= ~EDGE_ABNORMAL;
2361 /* See if this edge is one we should keep. */
2362 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2363 /* A conditional jump can fall through into the next
2364 block, so we should keep the edge. */
2369 else if (e->dest != EXIT_BLOCK_PTR
2370 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2371 /* If the destination block is the target of the jump,
2377 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2378 /* If the destination block is the exit block, and this
2379 instruction is a return, then keep the edge. */
2384 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2385 /* Keep the edges that correspond to exceptions thrown by
2386 this instruction and rematerialize the EDGE_ABNORMAL
2387 flag we just cleared above. */
2389 e->flags |= EDGE_ABNORMAL;
2394 /* We do not need this edge. */
2395 bb->flags |= BB_DIRTY;
2400 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2404 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2409 /* Redistribute probabilities. */
2410 if (EDGE_COUNT (bb->succs) == 1)
2412 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2413 EDGE_SUCC (bb, 0)->count = bb->count;
2417 note = find_reg_note (insn, REG_BR_PROB, NULL);
2421 b = BRANCH_EDGE (bb);
2422 f = FALLTHRU_EDGE (bb);
2423 b->probability = INTVAL (XEXP (note, 0));
2424 f->probability = REG_BR_PROB_BASE - b->probability;
2425 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2426 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2431 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2433 /* First, there should not be any EH or ABCALL edges resulting
2434 from non-local gotos and the like. If there were, we shouldn't
2435 have created the sibcall in the first place. Second, there
2436 should of course never have been a fallthru edge. */
2437 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2438 gcc_assert (EDGE_SUCC (bb, 0)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2443 /* If we don't see a jump insn, we don't know exactly why the block would
2444 have been broken at this point. Look for a simple, non-fallthru edge,
2445 as these are only created by conditional branches. If we find such an
2446 edge we know that there used to be a jump here and can then safely
2447 remove all non-fallthru edges. */
2449 FOR_EACH_EDGE (e, ei, bb->succs)
2450 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2459 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2461 if (!(e->flags & EDGE_FALLTHRU))
2463 bb->flags |= BB_DIRTY;
2471 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2473 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2474 EDGE_SUCC (bb, 0)->count = bb->count;
2477 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2482 /* Search all basic blocks for potentially dead edges and purge them. Return
2483 true if some edge has been eliminated. */
2486 purge_all_dead_edges (int update_life_p)
2494 blocks = sbitmap_alloc (last_basic_block);
2495 sbitmap_zero (blocks);
2500 bool purged_here = purge_dead_edges (bb);
2502 purged |= purged_here;
2503 if (purged_here && update_life_p)
2504 SET_BIT (blocks, bb->index);
2507 if (update_life_p && purged)
2508 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2509 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2510 | PROP_KILL_DEAD_CODE);
2513 sbitmap_free (blocks);
2517 /* Same as split_block but update cfg_layout structures. */
2520 cfg_layout_split_block (basic_block bb, void *insnp)
2523 basic_block new_bb = rtl_split_block (bb, insn);
2525 new_bb->rbi->footer = bb->rbi->footer;
2526 bb->rbi->footer = NULL;
2532 /* Redirect Edge to DEST. */
2534 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2536 basic_block src = e->src;
2539 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2542 if (e->dest == dest)
2545 if (e->src != ENTRY_BLOCK_PTR
2546 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2548 src->flags |= BB_DIRTY;
2552 if (e->src == ENTRY_BLOCK_PTR
2553 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2556 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2557 e->src->index, dest->index);
2559 e->src->flags |= BB_DIRTY;
2560 redirect_edge_succ (e, dest);
2564 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2565 in the case the basic block appears to be in sequence. Avoid this
2568 if (e->flags & EDGE_FALLTHRU)
2570 /* Redirect any branch edges unified with the fallthru one. */
2571 if (JUMP_P (BB_END (src))
2572 && label_is_jump_target_p (BB_HEAD (e->dest),
2578 fprintf (dump_file, "Fallthru edge unified with branch "
2579 "%i->%i redirected to %i\n",
2580 e->src->index, e->dest->index, dest->index);
2581 e->flags &= ~EDGE_FALLTHRU;
2582 redirected = redirect_branch_edge (e, dest);
2583 gcc_assert (redirected);
2584 e->flags |= EDGE_FALLTHRU;
2585 e->src->flags |= BB_DIRTY;
2588 /* In case we are redirecting fallthru edge to the branch edge
2589 of conditional jump, remove it. */
2590 if (EDGE_COUNT (src->succs) == 2)
2597 FOR_EACH_EDGE (tmp, ei, src->succs)
2607 if (EDGE_COUNT (src->succs) > (ix + 1))
2608 s = EDGE_SUCC (src, ix + 1);
2610 s = EDGE_SUCC (src, 0);
2613 && any_condjump_p (BB_END (src))
2614 && onlyjump_p (BB_END (src)))
2615 delete_insn (BB_END (src));
2617 ret = redirect_edge_succ_nodup (e, dest);
2619 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2620 e->src->index, e->dest->index, dest->index);
2623 ret = redirect_branch_edge (e, dest);
2625 /* We don't want simplejumps in the insn stream during cfglayout. */
2626 gcc_assert (!simplejump_p (BB_END (src)));
2628 src->flags |= BB_DIRTY;
2632 /* Simple wrapper as we always can redirect fallthru edges. */
2634 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2636 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2638 gcc_assert (redirected);
2642 /* Same as delete_basic_block but update cfg_layout structures. */
2645 cfg_layout_delete_block (basic_block bb)
2647 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2649 if (bb->rbi->header)
2651 next = BB_HEAD (bb);
2653 NEXT_INSN (prev) = bb->rbi->header;
2655 set_first_insn (bb->rbi->header);
2656 PREV_INSN (bb->rbi->header) = prev;
2657 insn = bb->rbi->header;
2658 while (NEXT_INSN (insn))
2659 insn = NEXT_INSN (insn);
2660 NEXT_INSN (insn) = next;
2661 PREV_INSN (next) = insn;
2663 next = NEXT_INSN (BB_END (bb));
2664 if (bb->rbi->footer)
2666 insn = bb->rbi->footer;
2669 if (BARRIER_P (insn))
2671 if (PREV_INSN (insn))
2672 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2674 bb->rbi->footer = NEXT_INSN (insn);
2675 if (NEXT_INSN (insn))
2676 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2680 insn = NEXT_INSN (insn);
2682 if (bb->rbi->footer)
2685 NEXT_INSN (insn) = bb->rbi->footer;
2686 PREV_INSN (bb->rbi->footer) = insn;
2687 while (NEXT_INSN (insn))
2688 insn = NEXT_INSN (insn);
2689 NEXT_INSN (insn) = next;
2691 PREV_INSN (next) = insn;
2693 set_last_insn (insn);
2696 if (bb->next_bb != EXIT_BLOCK_PTR)
2697 to = &bb->next_bb->rbi->header;
2699 to = &cfg_layout_function_footer;
2700 rtl_delete_block (bb);
2703 prev = NEXT_INSN (prev);
2705 prev = get_insns ();
2707 next = PREV_INSN (next);
2709 next = get_last_insn ();
2711 if (next && NEXT_INSN (next) != prev)
2713 remaints = unlink_insn_chain (prev, next);
2715 while (NEXT_INSN (insn))
2716 insn = NEXT_INSN (insn);
2717 NEXT_INSN (insn) = *to;
2719 PREV_INSN (*to) = insn;
2724 /* Return true when blocks A and B can be safely merged. */
2726 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2728 /* If we are partitioning hot/cold basic blocks, we don't want to
2729 mess up unconditional or indirect jumps that cross between hot
2732 Basic block partitioning may result in some jumps that appear to
2733 be optimizable (or blocks that appear to be mergeable), but which really
2734 must be left untouched (they are required to make it safely across
2735 partition boundaries). See the comments at the top of
2736 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2738 if (flag_reorder_blocks_and_partition
2739 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2740 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2741 || BB_PARTITION (a) != BB_PARTITION (b)))
2744 /* There must be exactly one edge in between the blocks. */
2745 return (EDGE_COUNT (a->succs) == 1
2746 && EDGE_SUCC (a, 0)->dest == b
2747 && EDGE_COUNT (b->preds) == 1
2749 /* Must be simple edge. */
2750 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
2751 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2752 /* If the jump insn has side effects,
2753 we can't kill the edge. */
2754 && (!JUMP_P (BB_END (a))
2755 || (reload_completed
2756 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2759 /* Merge block A and B, abort when it is not possible. */
2761 cfg_layout_merge_blocks (basic_block a, basic_block b)
2763 #ifdef ENABLE_CHECKING
2764 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2767 /* If there was a CODE_LABEL beginning B, delete it. */
2768 if (LABEL_P (BB_HEAD (b)))
2769 delete_insn (BB_HEAD (b));
2771 /* We should have fallthru edge in a, or we can do dummy redirection to get
2773 if (JUMP_P (BB_END (a)))
2774 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2775 gcc_assert (!JUMP_P (BB_END (a)));
2777 /* Possible line number notes should appear in between. */
2780 rtx first = BB_END (a), last;
2782 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2783 delete_insn_chain (NEXT_INSN (first), last);
2784 b->rbi->header = NULL;
2787 /* In the case basic blocks are not adjacent, move them around. */
2788 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2790 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2792 emit_insn_after_noloc (first, BB_END (a));
2793 /* Skip possible DELETED_LABEL insn. */
2794 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2795 first = NEXT_INSN (first);
2796 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2798 delete_insn (first);
2800 /* Otherwise just re-associate the instructions. */
2805 for (insn = BB_HEAD (b);
2806 insn != NEXT_INSN (BB_END (b));
2807 insn = NEXT_INSN (insn))
2808 set_block_for_insn (insn, a);
2810 /* Skip possible DELETED_LABEL insn. */
2811 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2812 insn = NEXT_INSN (insn);
2813 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2815 BB_END (a) = BB_END (b);
2819 /* Possible tablejumps and barriers should appear after the block. */
2822 if (!a->rbi->footer)
2823 a->rbi->footer = b->rbi->footer;
2826 rtx last = a->rbi->footer;
2828 while (NEXT_INSN (last))
2829 last = NEXT_INSN (last);
2830 NEXT_INSN (last) = b->rbi->footer;
2831 PREV_INSN (b->rbi->footer) = last;
2833 b->rbi->footer = NULL;
2837 fprintf (dump_file, "Merged blocks %d and %d.\n",
2838 a->index, b->index);
2844 cfg_layout_split_edge (edge e)
2847 basic_block new_bb =
2848 create_basic_block (e->src != ENTRY_BLOCK_PTR
2849 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2852 /* ??? This info is likely going to be out of date very soon, but we must
2853 create it to avoid getting an ICE later. */
2854 if (e->dest->global_live_at_start)
2856 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2857 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2858 COPY_REG_SET (new_bb->global_live_at_start,
2859 e->dest->global_live_at_start);
2860 COPY_REG_SET (new_bb->global_live_at_end,
2861 e->dest->global_live_at_start);
2864 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2865 redirect_edge_and_branch_force (e, new_bb);
2870 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2873 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2877 /* Return 1 if BB ends with a call, possibly followed by some
2878 instructions that must stay with the call, 0 otherwise. */
2881 rtl_block_ends_with_call_p (basic_block bb)
2883 rtx insn = BB_END (bb);
2885 while (!CALL_P (insn)
2886 && insn != BB_HEAD (bb)
2887 && keep_with_call_p (insn))
2888 insn = PREV_INSN (insn);
2889 return (CALL_P (insn));
2892 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2895 rtl_block_ends_with_condjump_p (basic_block bb)
2897 return any_condjump_p (BB_END (bb));
2900 /* Return true if we need to add fake edge to exit.
2901 Helper function for rtl_flow_call_edges_add. */
2904 need_fake_edge_p (rtx insn)
2910 && !SIBLING_CALL_P (insn)
2911 && !find_reg_note (insn, REG_NORETURN, NULL)
2912 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2913 && !CONST_OR_PURE_CALL_P (insn)))
2916 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2917 && MEM_VOLATILE_P (PATTERN (insn)))
2918 || (GET_CODE (PATTERN (insn)) == PARALLEL
2919 && asm_noperands (insn) != -1
2920 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2921 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2924 /* Add fake edges to the function exit for any non constant and non noreturn
2925 calls, volatile inline assembly in the bitmap of blocks specified by
2926 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2929 The goal is to expose cases in which entering a basic block does not imply
2930 that all subsequent instructions must be executed. */
2933 rtl_flow_call_edges_add (sbitmap blocks)
2936 int blocks_split = 0;
2937 int last_bb = last_basic_block;
2938 bool check_last_block = false;
2940 if (n_basic_blocks == 0)
2944 check_last_block = true;
2946 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2948 /* In the last basic block, before epilogue generation, there will be
2949 a fallthru edge to EXIT. Special care is required if the last insn
2950 of the last basic block is a call because make_edge folds duplicate
2951 edges, which would result in the fallthru edge also being marked
2952 fake, which would result in the fallthru edge being removed by
2953 remove_fake_edges, which would result in an invalid CFG.
2955 Moreover, we can't elide the outgoing fake edge, since the block
2956 profiler needs to take this into account in order to solve the minimal
2957 spanning tree in the case that the call doesn't return.
2959 Handle this by adding a dummy instruction in a new last basic block. */
2960 if (check_last_block)
2962 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2963 rtx insn = BB_END (bb);
2965 /* Back up past insns that must be kept in the same block as a call. */
2966 while (insn != BB_HEAD (bb)
2967 && keep_with_call_p (insn))
2968 insn = PREV_INSN (insn);
2970 if (need_fake_edge_p (insn))
2975 FOR_EACH_EDGE (e, ei, bb->succs)
2976 if (e->dest == EXIT_BLOCK_PTR)
2978 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2979 commit_edge_insertions ();
2985 /* Now add fake edges to the function exit for any non constant
2986 calls since there is no way that we can determine if they will
2989 for (i = 0; i < last_bb; i++)
2991 basic_block bb = BASIC_BLOCK (i);
2998 if (blocks && !TEST_BIT (blocks, i))
3001 for (insn = BB_END (bb); ; insn = prev_insn)
3003 prev_insn = PREV_INSN (insn);
3004 if (need_fake_edge_p (insn))
3007 rtx split_at_insn = insn;
3009 /* Don't split the block between a call and an insn that should
3010 remain in the same block as the call. */
3012 while (split_at_insn != BB_END (bb)
3013 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3014 split_at_insn = NEXT_INSN (split_at_insn);
3016 /* The handling above of the final block before the epilogue
3017 should be enough to verify that there is no edge to the exit
3018 block in CFG already. Calling make_edge in such case would
3019 cause us to mark that edge as fake and remove it later. */
3021 #ifdef ENABLE_CHECKING
3022 if (split_at_insn == BB_END (bb))
3025 FOR_EACH_EDGE (e, ei, bb->succs)
3026 gcc_assert (e->dest != EXIT_BLOCK_PTR);
3030 /* Note that the following may create a new basic block
3031 and renumber the existing basic blocks. */
3032 if (split_at_insn != BB_END (bb))
3034 e = split_block (bb, split_at_insn);
3039 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3042 if (insn == BB_HEAD (bb))
3048 verify_flow_info ();
3050 return blocks_split;
3053 /* Implementation of CFG manipulation for linearized RTL. */
3054 struct cfg_hooks rtl_cfg_hooks = {
3056 rtl_verify_flow_info,
3058 rtl_create_basic_block,
3059 rtl_redirect_edge_and_branch,
3060 rtl_redirect_edge_and_branch_force,
3063 rtl_move_block_after,
3064 rtl_can_merge_blocks, /* can_merge_blocks_p */
3068 NULL, /* can_duplicate_block_p */
3069 NULL, /* duplicate_block */
3071 rtl_make_forwarder_block,
3072 rtl_tidy_fallthru_edge,
3073 rtl_block_ends_with_call_p,
3074 rtl_block_ends_with_condjump_p,
3075 rtl_flow_call_edges_add
3078 /* Implementation of CFG manipulation for cfg layout RTL, where
3079 basic block connected via fallthru edges does not have to be adjacent.
3080 This representation will hopefully become the default one in future
3081 version of the compiler. */
3083 /* We do not want to declare these functions in a header file, since they
3084 should only be used through the cfghooks interface, and we do not want to
3085 move them here since it would require also moving quite a lot of related
3087 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3088 extern basic_block cfg_layout_duplicate_bb (basic_block);
3090 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3092 rtl_verify_flow_info_1,
3094 cfg_layout_create_basic_block,
3095 cfg_layout_redirect_edge_and_branch,
3096 cfg_layout_redirect_edge_and_branch_force,
3097 cfg_layout_delete_block,
3098 cfg_layout_split_block,
3099 rtl_move_block_after,
3100 cfg_layout_can_merge_blocks_p,
3101 cfg_layout_merge_blocks,
3104 cfg_layout_can_duplicate_bb_p,
3105 cfg_layout_duplicate_bb,
3106 cfg_layout_split_edge,
3107 rtl_make_forwarder_block,
3109 rtl_block_ends_with_call_p,
3110 rtl_block_ends_with_condjump_p,
3111 rtl_flow_call_edges_add