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 if (INSN_DELETED_P (insn))
145 INSN_DELETED_P (insn) = 1;
148 /* If deleting a jump, decrement the use count of the label. Deleting
149 the label itself should happen in the normal course of block merging. */
152 && LABEL_P (JUMP_LABEL (insn)))
153 LABEL_NUSES (JUMP_LABEL (insn))--;
155 /* Also if deleting an insn that references a label. */
158 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
159 && LABEL_P (XEXP (note, 0)))
161 LABEL_NUSES (XEXP (note, 0))--;
162 remove_note (insn, note);
167 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
168 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
170 rtx pat = PATTERN (insn);
171 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
172 int len = XVECLEN (pat, diff_vec_p);
175 for (i = 0; i < len; i++)
177 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
179 /* When deleting code in bulk (e.g. removing many unreachable
180 blocks) we can delete a label that's a target of the vector
181 before deleting the vector itself. */
183 LABEL_NUSES (label)--;
190 /* Like delete_insn but also purge dead edges from BB. */
192 delete_insn_and_edges (rtx insn)
198 && BLOCK_FOR_INSN (insn)
199 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
201 x = delete_insn (insn);
203 purge_dead_edges (BLOCK_FOR_INSN (insn));
207 /* Unlink a chain of insns between START and FINISH, leaving notes
208 that must be paired. */
211 delete_insn_chain (rtx start, rtx finish)
215 /* Unchain the insns one by one. It would be quicker to delete all of these
216 with a single unchaining, rather than one at a time, but we need to keep
220 next = NEXT_INSN (start);
221 if (NOTE_P (start) && !can_delete_note_p (start))
224 next = delete_insn (start);
232 /* Like delete_insn but also purge dead edges from BB. */
234 delete_insn_chain_and_edges (rtx first, rtx last)
239 && BLOCK_FOR_INSN (last)
240 && BB_END (BLOCK_FOR_INSN (last)) == last)
242 delete_insn_chain (first, last);
244 purge_dead_edges (BLOCK_FOR_INSN (last));
247 /* Create a new basic block consisting of the instructions between HEAD and END
248 inclusive. This function is designed to allow fast BB construction - reuses
249 the note and basic block struct in BB_NOTE, if any and do not grow
250 BASIC_BLOCK chain and should be used directly only by CFG construction code.
251 END can be NULL in to create new empty basic block before HEAD. Both END
252 and HEAD can be NULL to create basic block at the end of INSN chain.
253 AFTER is the basic block we should be put after. */
256 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
261 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
264 /* If we found an existing note, thread it back onto the chain. */
272 after = PREV_INSN (head);
276 if (after != bb_note && NEXT_INSN (after) != bb_note)
277 reorder_insns_nobb (bb_note, bb_note, after);
281 /* Otherwise we must create a note and a basic block structure. */
287 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
288 else if (LABEL_P (head) && end)
290 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
296 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
302 NOTE_BASIC_BLOCK (bb_note) = bb;
305 /* Always include the bb note in the block. */
306 if (NEXT_INSN (end) == bb_note)
311 bb->index = last_basic_block++;
313 link_block (bb, after);
314 BASIC_BLOCK (bb->index) = bb;
315 update_bb_for_insn (bb);
316 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
318 /* Tag the block so that we know it has been used when considering
319 other basic block notes. */
325 /* Create new basic block consisting of instructions in between HEAD and END
326 and place it to the BB chain after block AFTER. END can be NULL in to
327 create new empty basic block before HEAD. Both END and HEAD can be NULL to
328 create basic block at the end of INSN chain. */
331 rtl_create_basic_block (void *headp, void *endp, basic_block after)
333 rtx head = headp, end = endp;
336 /* Grow the basic block array if needed. */
337 if ((size_t) last_basic_block >= VARRAY_SIZE (basic_block_info))
339 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
340 VARRAY_GROW (basic_block_info, new_size);
345 bb = create_basic_block_structure (head, end, NULL, after);
351 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
353 basic_block newbb = rtl_create_basic_block (head, end, after);
355 initialize_bb_rbi (newbb);
359 /* Delete the insns in a (non-live) block. We physically delete every
360 non-deleted-note insn, and update the flow graph appropriately.
362 Return nonzero if we deleted an exception handler. */
364 /* ??? Preserving all such notes strikes me as wrong. It would be nice
365 to post-process the stream to remove empty blocks, loops, ranges, etc. */
368 rtl_delete_block (basic_block b)
372 /* If the head of this block is a CODE_LABEL, then it might be the
373 label for an exception handler which can't be reached.
375 We need to remove the label from the exception_handler_label list
376 and remove the associated NOTE_INSN_EH_REGION_BEG and
377 NOTE_INSN_EH_REGION_END notes. */
379 /* Get rid of all NOTE_INSN_LOOP_CONTs hanging before the block. */
381 for (insn = PREV_INSN (BB_HEAD (b)); insn; insn = PREV_INSN (insn))
385 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
386 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
392 maybe_remove_eh_handler (insn);
394 /* Include any jump table following the basic block. */
396 if (tablejump_p (end, NULL, &tmp))
399 /* Include any barrier that may follow the basic block. */
400 tmp = next_nonnote_insn (end);
401 if (tmp && BARRIER_P (tmp))
404 /* Selectively delete the entire chain. */
406 delete_insn_chain (insn, end);
409 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
412 compute_bb_for_insn (void)
418 rtx end = BB_END (bb);
421 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
423 BLOCK_FOR_INSN (insn) = bb;
430 /* Release the basic_block_for_insn array. */
433 free_bb_for_insn (void)
436 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
437 if (!BARRIER_P (insn))
438 BLOCK_FOR_INSN (insn) = NULL;
441 /* Return RTX to emit after when we want to emit code on the entry of function. */
443 entry_of_function (void)
445 return (n_basic_blocks ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
448 /* Update insns block within BB. */
451 update_bb_for_insn (basic_block bb)
455 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
457 if (!BARRIER_P (insn))
458 set_block_for_insn (insn, bb);
459 if (insn == BB_END (bb))
464 /* Creates a new basic block just after basic block B by splitting
465 everything after specified instruction I. */
468 rtl_split_block (basic_block bb, void *insnp)
476 insn = first_insn_after_basic_block_note (bb);
479 insn = PREV_INSN (insn);
481 insn = get_last_insn ();
484 /* We probably should check type of the insn so that we do not create
485 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
487 if (insn == BB_END (bb))
488 emit_note_after (NOTE_INSN_DELETED, insn);
490 /* Create the new basic block. */
491 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
492 BB_COPY_PARTITION (new_bb, bb);
495 /* Redirect the outgoing edges. */
496 new_bb->succ = bb->succ;
498 for (e = new_bb->succ; e; e = e->succ_next)
501 if (bb->global_live_at_start)
503 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
504 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
505 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
507 /* We now have to calculate which registers are live at the end
508 of the split basic block and at the start of the new basic
509 block. Start with those registers that are known to be live
510 at the end of the original basic block and get
511 propagate_block to determine which registers are live. */
512 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
513 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
514 COPY_REG_SET (bb->global_live_at_end,
515 new_bb->global_live_at_start);
516 #ifdef HAVE_conditional_execution
517 /* In the presence of conditional execution we are not able to update
518 liveness precisely. */
519 if (reload_completed)
521 bb->flags |= BB_DIRTY;
522 new_bb->flags |= BB_DIRTY;
530 /* Blocks A and B are to be merged into a single block A. The insns
531 are already contiguous. */
534 rtl_merge_blocks (basic_block a, basic_block b)
536 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
537 rtx del_first = NULL_RTX, del_last = NULL_RTX;
540 /* If there was a CODE_LABEL beginning B, delete it. */
541 if (LABEL_P (b_head))
543 /* Detect basic blocks with nothing but a label. This can happen
544 in particular at the end of a function. */
548 del_first = del_last = b_head;
549 b_head = NEXT_INSN (b_head);
552 /* Delete the basic block note and handle blocks containing just that
554 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
562 b_head = NEXT_INSN (b_head);
565 /* If there was a jump out of A, delete it. */
570 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
572 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
573 || prev == BB_HEAD (a))
579 /* If this was a conditional jump, we need to also delete
580 the insn that set cc0. */
581 if (only_sets_cc0_p (prev))
585 prev = prev_nonnote_insn (prev);
592 a_end = PREV_INSN (del_first);
594 else if (BARRIER_P (NEXT_INSN (a_end)))
595 del_first = NEXT_INSN (a_end);
597 /* Delete everything marked above as well as crap that might be
598 hanging out between the two blocks. */
600 delete_insn_chain (del_first, del_last);
602 /* Reassociate the insns of B with A. */
607 for (x = a_end; x != b_end; x = NEXT_INSN (x))
608 set_block_for_insn (x, a);
610 set_block_for_insn (b_end, a);
618 /* Return true when block A and B can be merged. */
620 rtl_can_merge_blocks (basic_block a,basic_block b)
622 /* If we are partitioning hot/cold basic blocks, we don't want to
623 mess up unconditional or indirect jumps that cross between hot
626 ??? If two basic blocks could otherwise be merged (which implies
627 that the jump between the two is unconditional), and one is in a
628 hot section and the other is in a cold section, surely that means
629 that one of the section choices is wrong. */
631 if (flag_reorder_blocks_and_partition
632 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
633 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
634 || BB_PARTITION (a) != BB_PARTITION (b)))
637 /* There must be exactly one edge in between the blocks. */
638 return (a->succ && !a->succ->succ_next && a->succ->dest == b
639 && !b->pred->pred_next && a != b
640 /* Must be simple edge. */
641 && !(a->succ->flags & EDGE_COMPLEX)
643 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
644 /* If the jump insn has side effects,
645 we can't kill the edge. */
646 && (!JUMP_P (BB_END (a))
648 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
651 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
655 block_label (basic_block block)
657 if (block == EXIT_BLOCK_PTR)
660 if (!LABEL_P (BB_HEAD (block)))
662 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
665 return BB_HEAD (block);
668 /* Attempt to perform edge redirection by replacing possibly complex jump
669 instruction by unconditional jump or removing jump completely. This can
670 apply only if all edges now point to the same block. The parameters and
671 return values are equivalent to redirect_edge_and_branch. */
674 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
676 basic_block src = e->src;
677 rtx insn = BB_END (src), kill_from;
683 /* If we are partitioning hot/cold basic blocks, we don't want to
684 mess up unconditional or indirect jumps that cross between hot
685 and cold sections. */
687 if (flag_reorder_blocks_and_partition
688 && (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
689 || BB_PARTITION (src) != BB_PARTITION (target)))
692 /* Verify that all targets will be TARGET. */
693 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
694 if (tmp->dest != target && tmp != e)
697 if (tmp || !onlyjump_p (insn))
699 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
702 /* Avoid removing branch with side effects. */
703 set = single_set (insn);
704 if (!set || side_effects_p (set))
707 /* In case we zap a conditional jump, we'll need to kill
708 the cc0 setter too. */
711 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
712 kill_from = PREV_INSN (insn);
715 /* See if we can create the fallthru edge. */
716 if (in_cfglayout || can_fallthru (src, target))
719 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
722 /* Selectively unlink whole insn chain. */
725 rtx insn = src->rbi->footer;
727 delete_insn_chain (kill_from, BB_END (src));
729 /* Remove barriers but keep jumptables. */
732 if (BARRIER_P (insn))
734 if (PREV_INSN (insn))
735 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
737 src->rbi->footer = NEXT_INSN (insn);
738 if (NEXT_INSN (insn))
739 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
743 insn = NEXT_INSN (insn);
747 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
750 /* If this already is simplejump, redirect it. */
751 else if (simplejump_p (insn))
753 if (e->dest == target)
756 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
757 INSN_UID (insn), e->dest->index, target->index);
758 if (!redirect_jump (insn, block_label (target), 0))
760 if (target == EXIT_BLOCK_PTR)
766 /* Cannot do anything for target exit block. */
767 else if (target == EXIT_BLOCK_PTR)
770 /* Or replace possibly complicated jump insn by simple jump insn. */
773 rtx target_label = block_label (target);
774 rtx barrier, label, table;
776 emit_jump_insn_after (gen_jump (target_label), insn);
777 JUMP_LABEL (BB_END (src)) = target_label;
778 LABEL_NUSES (target_label)++;
780 fprintf (dump_file, "Replacing insn %i by jump %i\n",
781 INSN_UID (insn), INSN_UID (BB_END (src)));
784 delete_insn_chain (kill_from, insn);
786 /* Recognize a tablejump that we are converting to a
787 simple jump and remove its associated CODE_LABEL
788 and ADDR_VEC or ADDR_DIFF_VEC. */
789 if (tablejump_p (insn, &label, &table))
790 delete_insn_chain (label, table);
792 barrier = next_nonnote_insn (BB_END (src));
793 if (!barrier || !BARRIER_P (barrier))
794 emit_barrier_after (BB_END (src));
797 if (barrier != NEXT_INSN (BB_END (src)))
799 /* Move the jump before barrier so that the notes
800 which originally were or were created before jump table are
801 inside the basic block. */
802 rtx new_insn = BB_END (src);
805 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
806 tmp = NEXT_INSN (tmp))
807 set_block_for_insn (tmp, src);
809 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
810 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
812 NEXT_INSN (new_insn) = barrier;
813 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
815 PREV_INSN (new_insn) = PREV_INSN (barrier);
816 PREV_INSN (barrier) = new_insn;
821 /* Keep only one edge out and set proper flags. */
822 while (src->succ->succ_next)
823 remove_edge (src->succ);
826 e->flags = EDGE_FALLTHRU;
830 e->probability = REG_BR_PROB_BASE;
831 e->count = src->count;
833 /* We don't want a block to end on a line-number note since that has
834 the potential of changing the code between -g and not -g. */
835 while (NOTE_P (BB_END (e->src))
836 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
837 delete_insn (BB_END (e->src));
839 if (e->dest != target)
840 redirect_edge_succ (e, target);
845 /* Return last loop_beg note appearing after INSN, before start of next
846 basic block. Return INSN if there are no such notes.
848 When emitting jump to redirect a fallthru edge, it should always appear
849 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
850 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
854 last_loop_beg_note (rtx insn)
858 for (insn = NEXT_INSN (insn); insn && NOTE_P (insn)
859 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
860 insn = NEXT_INSN (insn))
861 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
867 /* Redirect edge representing branch of (un)conditional jump or tablejump,
870 redirect_branch_edge (edge e, basic_block target)
873 rtx old_label = BB_HEAD (e->dest);
874 basic_block src = e->src;
875 rtx insn = BB_END (src);
877 /* We can only redirect non-fallthru edges of jump insn. */
878 if (e->flags & EDGE_FALLTHRU)
880 else if (!JUMP_P (insn))
883 /* Recognize a tablejump and adjust all matching cases. */
884 if (tablejump_p (insn, NULL, &tmp))
888 rtx new_label = block_label (target);
890 if (target == EXIT_BLOCK_PTR)
892 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
893 vec = XVEC (PATTERN (tmp), 0);
895 vec = XVEC (PATTERN (tmp), 1);
897 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
898 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
900 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
901 --LABEL_NUSES (old_label);
902 ++LABEL_NUSES (new_label);
905 /* Handle casesi dispatch insns. */
906 if ((tmp = single_set (insn)) != NULL
907 && SET_DEST (tmp) == pc_rtx
908 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
909 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
910 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
912 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
914 --LABEL_NUSES (old_label);
915 ++LABEL_NUSES (new_label);
920 /* ?? We may play the games with moving the named labels from
921 one basic block to the other in case only one computed_jump is
923 if (computed_jump_p (insn)
924 /* A return instruction can't be redirected. */
925 || returnjump_p (insn))
928 /* If the insn doesn't go where we think, we're confused. */
929 if (JUMP_LABEL (insn) != old_label)
932 /* If the substitution doesn't succeed, die. This can happen
933 if the back end emitted unrecognizable instructions or if
934 target is exit block on some arches. */
935 if (!redirect_jump (insn, block_label (target), 0))
937 if (target == EXIT_BLOCK_PTR)
944 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
945 e->src->index, e->dest->index, target->index);
947 if (e->dest != target)
948 e = redirect_edge_succ_nodup (e, target);
952 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
953 expense of adding new instructions or reordering basic blocks.
955 Function can be also called with edge destination equivalent to the TARGET.
956 Then it should try the simplifications and do nothing if none is possible.
958 Return edge representing the branch if transformation succeeded. Return NULL
960 We still return NULL in case E already destinated TARGET and we didn't
961 managed to simplify instruction stream. */
964 rtl_redirect_edge_and_branch (edge e, basic_block target)
967 basic_block src = e->src;
969 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
972 if (e->dest == target)
975 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
977 src->flags |= BB_DIRTY;
981 ret = redirect_branch_edge (e, target);
985 src->flags |= BB_DIRTY;
989 /* Like force_nonfallthru below, but additionally performs redirection
990 Used by redirect_edge_and_branch_force. */
993 force_nonfallthru_and_redirect (edge e, basic_block target)
995 basic_block jump_block, new_bb = NULL, src = e->src;
998 int abnormal_edge_flags = 0;
1000 /* In the case the last instruction is conditional jump to the next
1001 instruction, first redirect the jump itself and then continue
1002 by creating a basic block afterwards to redirect fallthru edge. */
1003 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1004 && any_condjump_p (BB_END (e->src))
1005 /* When called from cfglayout, fallthru edges do not
1006 necessarily go to the next block. */
1007 && e->src->next_bb == e->dest
1008 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1011 edge b = unchecked_make_edge (e->src, target, 0);
1013 if (!redirect_jump (BB_END (e->src), block_label (target), 0))
1015 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1018 int prob = INTVAL (XEXP (note, 0));
1020 b->probability = prob;
1021 b->count = e->count * prob / REG_BR_PROB_BASE;
1022 e->probability -= e->probability;
1023 e->count -= b->count;
1024 if (e->probability < 0)
1031 if (e->flags & EDGE_ABNORMAL)
1033 /* Irritating special case - fallthru edge to the same block as abnormal
1035 We can't redirect abnormal edge, but we still can split the fallthru
1036 one and create separate abnormal edge to original destination.
1037 This allows bb-reorder to make such edge non-fallthru. */
1038 if (e->dest != target)
1040 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1041 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1043 else if (!(e->flags & EDGE_FALLTHRU))
1045 else if (e->src == ENTRY_BLOCK_PTR)
1047 /* We can't redirect the entry block. Create an empty block at the
1048 start of the function which we use to add the new jump. */
1050 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1052 /* Change the existing edge's source to be the new block, and add
1053 a new edge from the entry block to the new block. */
1055 for (pe1 = &ENTRY_BLOCK_PTR->succ; *pe1; pe1 = &(*pe1)->succ_next)
1058 *pe1 = e->succ_next;
1063 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1066 if (e->src->succ->succ_next || abnormal_edge_flags)
1068 /* Create the new structures. */
1070 /* If the old block ended with a tablejump, skip its table
1071 by searching forward from there. Otherwise start searching
1072 forward from the last instruction of the old block. */
1073 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1074 note = BB_END (e->src);
1076 /* Position the new block correctly relative to loop notes. */
1077 note = last_loop_beg_note (note);
1078 note = NEXT_INSN (note);
1080 jump_block = create_basic_block (note, NULL, e->src);
1081 jump_block->count = e->count;
1082 jump_block->frequency = EDGE_FREQUENCY (e);
1083 jump_block->loop_depth = target->loop_depth;
1085 if (target->global_live_at_start)
1087 jump_block->global_live_at_start
1088 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1089 jump_block->global_live_at_end
1090 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1091 COPY_REG_SET (jump_block->global_live_at_start,
1092 target->global_live_at_start);
1093 COPY_REG_SET (jump_block->global_live_at_end,
1094 target->global_live_at_start);
1097 /* Make sure new block ends up in correct hot/cold section. */
1099 BB_COPY_PARTITION (jump_block, e->src);
1100 if (flag_reorder_blocks_and_partition
1101 && targetm.have_named_sections)
1103 if (BB_PARTITION (jump_block) == BB_COLD_PARTITION)
1105 rtx bb_note, new_note;
1106 for (bb_note = BB_HEAD (jump_block);
1107 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1108 bb_note = NEXT_INSN (bb_note))
1109 if (NOTE_P (bb_note)
1110 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1112 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1114 NOTE_BASIC_BLOCK (new_note) = jump_block;
1116 if (JUMP_P (BB_END (jump_block))
1117 && !any_condjump_p (BB_END (jump_block))
1118 && (jump_block->succ->flags & EDGE_CROSSING))
1119 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1120 (REG_CROSSING_JUMP, NULL_RTX,
1121 REG_NOTES (BB_END (jump_block)));
1125 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1126 new_edge->probability = e->probability;
1127 new_edge->count = e->count;
1129 /* Redirect old edge. */
1130 redirect_edge_pred (e, jump_block);
1131 e->probability = REG_BR_PROB_BASE;
1133 new_bb = jump_block;
1136 jump_block = e->src;
1138 e->flags &= ~EDGE_FALLTHRU;
1139 if (target == EXIT_BLOCK_PTR)
1142 emit_jump_insn_after (gen_return (), BB_END (jump_block));
1149 rtx label = block_label (target);
1150 emit_jump_insn_after (gen_jump (label), BB_END (jump_block));
1151 JUMP_LABEL (BB_END (jump_block)) = label;
1152 LABEL_NUSES (label)++;
1155 emit_barrier_after (BB_END (jump_block));
1156 redirect_edge_succ_nodup (e, target);
1158 if (abnormal_edge_flags)
1159 make_edge (src, target, abnormal_edge_flags);
1164 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1165 (and possibly create new basic block) to make edge non-fallthru.
1166 Return newly created BB or NULL if none. */
1169 force_nonfallthru (edge e)
1171 return force_nonfallthru_and_redirect (e, e->dest);
1174 /* Redirect edge even at the expense of creating new jump insn or
1175 basic block. Return new basic block if created, NULL otherwise.
1176 Abort if conversion is impossible. */
1179 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1181 if (redirect_edge_and_branch (e, target)
1182 || e->dest == target)
1185 /* In case the edge redirection failed, try to force it to be non-fallthru
1186 and redirect newly created simplejump. */
1187 return force_nonfallthru_and_redirect (e, target);
1190 /* The given edge should potentially be a fallthru edge. If that is in
1191 fact true, delete the jump and barriers that are in the way. */
1194 rtl_tidy_fallthru_edge (edge e)
1197 basic_block b = e->src, c = b->next_bb;
1199 /* ??? In a late-running flow pass, other folks may have deleted basic
1200 blocks by nopping out blocks, leaving multiple BARRIERs between here
1201 and the target label. They ought to be chastized and fixed.
1203 We can also wind up with a sequence of undeletable labels between
1204 one block and the next.
1206 So search through a sequence of barriers, labels, and notes for
1207 the head of block C and assert that we really do fall through. */
1209 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1213 /* Remove what will soon cease being the jump insn from the source block.
1214 If block B consisted only of this single jump, turn it into a deleted
1219 && (any_uncondjump_p (q)
1220 || (b->succ == e && e->succ_next == NULL)))
1223 /* If this was a conditional jump, we need to also delete
1224 the insn that set cc0. */
1225 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1231 /* We don't want a block to end on a line-number note since that has
1232 the potential of changing the code between -g and not -g. */
1233 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1237 /* Selectively unlink the sequence. */
1238 if (q != PREV_INSN (BB_HEAD (c)))
1239 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1241 e->flags |= EDGE_FALLTHRU;
1244 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1245 is back edge of syntactic loop. */
1248 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1257 /* ??? Could we guarantee that bb indices are monotone, so that we could
1258 just compare them? */
1259 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1265 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1266 insn = NEXT_INSN (insn))
1269 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1271 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1278 /* Should move basic block BB after basic block AFTER. NIY. */
1281 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1282 basic_block after ATTRIBUTE_UNUSED)
1287 /* Split a (typically critical) edge. Return the new block.
1288 Abort on abnormal edges.
1290 ??? The code generally expects to be called on critical edges.
1291 The case of a block ending in an unconditional jump to a
1292 block with multiple predecessors is not handled optimally. */
1295 rtl_split_edge (edge edge_in)
1300 /* Abnormal edges cannot be split. */
1301 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1304 /* We are going to place the new block in front of edge destination.
1305 Avoid existence of fallthru predecessors. */
1306 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1310 for (e = edge_in->dest->pred; e; e = e->pred_next)
1311 if (e->flags & EDGE_FALLTHRU)
1315 force_nonfallthru (e);
1318 /* Create the basic block note.
1320 Where we place the note can have a noticeable impact on the generated
1321 code. Consider this cfg:
1331 If we need to insert an insn on the edge from block 0 to block 1,
1332 we want to ensure the instructions we insert are outside of any
1333 loop notes that physically sit between block 0 and block 1. Otherwise
1334 we confuse the loop optimizer into thinking the loop is a phony. */
1336 if (edge_in->dest != EXIT_BLOCK_PTR
1337 && PREV_INSN (BB_HEAD (edge_in->dest))
1338 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1339 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1340 == NOTE_INSN_LOOP_BEG)
1341 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1342 before = PREV_INSN (BB_HEAD (edge_in->dest));
1343 else if (edge_in->dest != EXIT_BLOCK_PTR)
1344 before = BB_HEAD (edge_in->dest);
1348 /* If this is a fall through edge to the exit block, the blocks might be
1349 not adjacent, and the right place is the after the source. */
1350 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1352 before = NEXT_INSN (BB_END (edge_in->src));
1355 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1356 before = NEXT_INSN (before);
1357 bb = create_basic_block (before, NULL, edge_in->src);
1358 BB_COPY_PARTITION (bb, edge_in->src);
1362 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1363 /* ??? Why not edge_in->dest->prev_bb here? */
1364 BB_COPY_PARTITION (bb, edge_in->dest);
1367 /* ??? This info is likely going to be out of date very soon. */
1368 if (edge_in->dest->global_live_at_start)
1370 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1371 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1372 COPY_REG_SET (bb->global_live_at_start,
1373 edge_in->dest->global_live_at_start);
1374 COPY_REG_SET (bb->global_live_at_end,
1375 edge_in->dest->global_live_at_start);
1378 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1380 /* For non-fallthru edges, we must adjust the predecessor's
1381 jump instruction to target our new block. */
1382 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1384 if (!redirect_edge_and_branch (edge_in, bb))
1388 redirect_edge_succ (edge_in, bb);
1393 /* Queue instructions for insertion on an edge between two basic blocks.
1394 The new instructions and basic blocks (if any) will not appear in the
1395 CFG until commit_edge_insertions is called. */
1398 insert_insn_on_edge (rtx pattern, edge e)
1400 /* We cannot insert instructions on an abnormal critical edge.
1401 It will be easier to find the culprit if we die now. */
1402 if ((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))
1405 if (e->insns.r == NULL_RTX)
1408 push_to_sequence (e->insns.r);
1410 emit_insn (pattern);
1412 e->insns.r = get_insns ();
1416 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1417 registers that are killed by the store. */
1419 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1421 regset killed = data;
1424 if (GET_CODE (reg) == SUBREG)
1425 reg = SUBREG_REG (reg);
1428 regno = REGNO (reg);
1429 if (regno >= FIRST_PSEUDO_REGISTER)
1430 SET_REGNO_REG_SET (killed, regno);
1433 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1434 SET_REGNO_REG_SET (killed, regno + i);
1438 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1439 it checks whether this will not clobber the registers that are live on the
1440 edge (i.e. it requires liveness information to be up-to-date) and if there
1441 are some, then it tries to save and restore them. Returns true if
1444 safe_insert_insn_on_edge (rtx insn, edge e)
1447 regset_head killed_head;
1448 regset killed = INITIALIZE_REG_SET (killed_head);
1449 rtx save_regs = NULL_RTX;
1450 int regno, noccmode;
1451 enum machine_mode mode;
1453 #ifdef AVOID_CCMODE_COPIES
1459 for (x = insn; x; x = NEXT_INSN (x))
1461 note_stores (PATTERN (x), mark_killed_regs, killed);
1462 bitmap_operation (killed, killed, e->dest->global_live_at_start,
1465 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno,
1467 mode = regno < FIRST_PSEUDO_REGISTER
1468 ? reg_raw_mode[regno]
1469 : GET_MODE (regno_reg_rtx[regno]);
1470 if (mode == VOIDmode)
1473 if (noccmode && mode == CCmode)
1476 save_regs = alloc_EXPR_LIST (0,
1479 gen_raw_REG (mode, regno)),
1488 for (x = save_regs; x; x = XEXP (x, 1))
1490 from = XEXP (XEXP (x, 0), 1);
1491 to = XEXP (XEXP (x, 0), 0);
1492 emit_move_insn (to, from);
1495 for (x = save_regs; x; x = XEXP (x, 1))
1497 from = XEXP (XEXP (x, 0), 0);
1498 to = XEXP (XEXP (x, 0), 1);
1499 emit_move_insn (to, from);
1501 insn = get_insns ();
1503 free_EXPR_LIST_list (&save_regs);
1505 insert_insn_on_edge (insn, e);
1507 FREE_REG_SET (killed);
1511 /* Update the CFG for the instructions queued on edge E. */
1514 commit_one_edge_insertion (edge e, int watch_calls)
1516 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1517 basic_block bb = NULL;
1519 /* Pull the insns off the edge now since the edge might go away. */
1521 e->insns.r = NULL_RTX;
1523 /* Special case -- avoid inserting code between call and storing
1524 its return value. */
1525 if (watch_calls && (e->flags & EDGE_FALLTHRU) && !e->dest->pred->pred_next
1526 && e->src != ENTRY_BLOCK_PTR
1527 && CALL_P (BB_END (e->src)))
1529 rtx next = next_nonnote_insn (BB_END (e->src));
1531 after = BB_HEAD (e->dest);
1532 /* The first insn after the call may be a stack pop, skip it. */
1534 && keep_with_call_p (next))
1537 next = next_nonnote_insn (next);
1541 if (!before && !after)
1543 /* Figure out where to put these things. If the destination has
1544 one predecessor, insert there. Except for the exit block. */
1545 if (e->dest->pred->pred_next == NULL && e->dest != EXIT_BLOCK_PTR)
1549 /* Get the location correct wrt a code label, and "nice" wrt
1550 a basic block note, and before everything else. */
1553 tmp = NEXT_INSN (tmp);
1554 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1555 tmp = NEXT_INSN (tmp);
1558 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1559 tmp = NEXT_INSN (tmp);
1560 if (tmp == BB_HEAD (bb))
1563 after = PREV_INSN (tmp);
1565 after = get_last_insn ();
1568 /* If the source has one successor and the edge is not abnormal,
1569 insert there. Except for the entry block. */
1570 else if ((e->flags & EDGE_ABNORMAL) == 0
1571 && e->src->succ->succ_next == NULL
1572 && e->src != ENTRY_BLOCK_PTR)
1576 /* It is possible to have a non-simple jump here. Consider a target
1577 where some forms of unconditional jumps clobber a register. This
1578 happens on the fr30 for example.
1580 We know this block has a single successor, so we can just emit
1581 the queued insns before the jump. */
1582 if (JUMP_P (BB_END (bb)))
1583 for (before = BB_END (bb);
1584 NOTE_P (PREV_INSN (before))
1585 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1586 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1590 /* We'd better be fallthru, or we've lost track of what's what. */
1591 if ((e->flags & EDGE_FALLTHRU) == 0)
1594 after = BB_END (bb);
1597 /* Otherwise we must split the edge. */
1600 bb = split_edge (e);
1601 after = BB_END (bb);
1603 if (flag_reorder_blocks_and_partition
1604 && targetm.have_named_sections
1605 && e->src != ENTRY_BLOCK_PTR
1606 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1607 && !(e->flags & EDGE_CROSSING))
1609 rtx bb_note, new_note, cur_insn;
1612 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1613 cur_insn = NEXT_INSN (cur_insn))
1614 if (NOTE_P (cur_insn)
1615 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1621 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1623 NOTE_BASIC_BLOCK (new_note) = bb;
1624 if (JUMP_P (BB_END (bb))
1625 && !any_condjump_p (BB_END (bb))
1626 && (bb->succ->flags & EDGE_CROSSING))
1627 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1628 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1629 if (after == bb_note)
1635 /* Now that we've found the spot, do the insertion. */
1639 emit_insn_before (insns, before);
1640 last = prev_nonnote_insn (before);
1643 last = emit_insn_after (insns, after);
1645 if (returnjump_p (last))
1647 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1648 This is not currently a problem because this only happens
1649 for the (single) epilogue, which already has a fallthru edge
1653 if (e->dest != EXIT_BLOCK_PTR
1654 || e->succ_next != NULL || (e->flags & EDGE_FALLTHRU) == 0)
1657 e->flags &= ~EDGE_FALLTHRU;
1658 emit_barrier_after (last);
1661 delete_insn (before);
1663 else if (JUMP_P (last))
1666 /* Mark the basic block for find_sub_basic_blocks. */
1670 /* Update the CFG for all queued instructions. */
1673 commit_edge_insertions (void)
1677 bool changed = false;
1679 #ifdef ENABLE_CHECKING
1680 verify_flow_info ();
1683 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1687 for (e = bb->succ; e; e = next)
1689 next = e->succ_next;
1693 commit_one_edge_insertion (e, false);
1701 blocks = sbitmap_alloc (last_basic_block);
1702 sbitmap_zero (blocks);
1706 SET_BIT (blocks, bb->index);
1707 /* Check for forgotten bb->aux values before commit_edge_insertions
1709 if (bb->aux != &bb->aux)
1713 find_many_sub_basic_blocks (blocks);
1714 sbitmap_free (blocks);
1717 /* Update the CFG for all queued instructions, taking special care of inserting
1718 code on edges between call and storing its return value. */
1721 commit_edge_insertions_watch_calls (void)
1725 bool changed = false;
1727 #ifdef ENABLE_CHECKING
1728 verify_flow_info ();
1731 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1735 for (e = bb->succ; e; e = next)
1737 next = e->succ_next;
1741 commit_one_edge_insertion (e, true);
1749 blocks = sbitmap_alloc (last_basic_block);
1750 sbitmap_zero (blocks);
1754 SET_BIT (blocks, bb->index);
1755 /* Check for forgotten bb->aux values before commit_edge_insertions
1757 if (bb->aux != &bb->aux)
1761 find_many_sub_basic_blocks (blocks);
1762 sbitmap_free (blocks);
1765 /* Print out RTL-specific basic block information (live information
1766 at start and end). */
1769 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1775 s_indent = alloca ((size_t) indent + 1);
1776 memset (s_indent, ' ', (size_t) indent);
1777 s_indent[indent] = '\0';
1779 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1780 dump_regset (bb->global_live_at_start, outf);
1783 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1784 insn = NEXT_INSN (insn))
1785 print_rtl_single (outf, insn);
1787 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1788 dump_regset (bb->global_live_at_end, outf);
1792 /* Like print_rtl, but also print out live information for the start of each
1796 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1801 fprintf (outf, "(nil)\n");
1804 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1805 int max_uid = get_max_uid ();
1806 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1807 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1808 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1812 FOR_EACH_BB_REVERSE (bb)
1816 start[INSN_UID (BB_HEAD (bb))] = bb;
1817 end[INSN_UID (BB_END (bb))] = bb;
1818 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1820 enum bb_state state = IN_MULTIPLE_BB;
1822 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1824 in_bb_p[INSN_UID (x)] = state;
1826 if (x == BB_END (bb))
1831 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1835 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1837 fprintf (outf, ";; Start of basic block %d, registers live:",
1839 dump_regset (bb->global_live_at_start, outf);
1843 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1844 && !NOTE_P (tmp_rtx)
1845 && !BARRIER_P (tmp_rtx))
1846 fprintf (outf, ";; Insn is not within a basic block\n");
1847 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1848 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1850 did_output = print_rtl_single (outf, tmp_rtx);
1852 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1854 fprintf (outf, ";; End of basic block %d, registers live:\n",
1856 dump_regset (bb->global_live_at_end, outf);
1869 if (current_function_epilogue_delay_list != 0)
1871 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1872 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1873 tmp_rtx = XEXP (tmp_rtx, 1))
1874 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1879 update_br_prob_note (basic_block bb)
1882 if (!JUMP_P (BB_END (bb)))
1884 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1885 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1887 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1890 /* Verify the CFG and RTL consistency common for both underlying RTL and
1893 Currently it does following checks:
1895 - test head/end pointers
1896 - overlapping of basic blocks
1897 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1898 - tails of basic blocks (ensure that boundary is necessary)
1899 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1900 and NOTE_INSN_BASIC_BLOCK
1901 - verify that no fall_thru edge crosses hot/cold partition boundaries
1903 In future it can be extended check a lot of other stuff as well
1904 (reachability of basic blocks, life information, etc. etc.). */
1907 rtl_verify_flow_info_1 (void)
1909 const int max_uid = get_max_uid ();
1910 rtx last_head = get_last_insn ();
1911 basic_block *bb_info;
1914 basic_block bb, last_bb_seen;
1916 bb_info = xcalloc (max_uid, sizeof (basic_block));
1918 /* Check bb chain & numbers. */
1919 last_bb_seen = ENTRY_BLOCK_PTR;
1921 FOR_EACH_BB_REVERSE (bb)
1923 rtx head = BB_HEAD (bb);
1924 rtx end = BB_END (bb);
1926 /* Verify the end of the basic block is in the INSN chain. */
1927 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1933 error ("end insn %d for block %d not found in the insn stream",
1934 INSN_UID (end), bb->index);
1938 /* Work backwards from the end to the head of the basic block
1939 to verify the head is in the RTL chain. */
1940 for (; x != NULL_RTX; x = PREV_INSN (x))
1942 /* While walking over the insn chain, verify insns appear
1943 in only one basic block and initialize the BB_INFO array
1944 used by other passes. */
1945 if (bb_info[INSN_UID (x)] != NULL)
1947 error ("insn %d is in multiple basic blocks (%d and %d)",
1948 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1952 bb_info[INSN_UID (x)] = bb;
1959 error ("head insn %d for block %d not found in the insn stream",
1960 INSN_UID (head), bb->index);
1967 /* Now check the basic blocks (boundaries etc.) */
1968 FOR_EACH_BB_REVERSE (bb)
1970 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1971 edge e, fallthru = NULL;
1974 if (INSN_P (BB_END (bb))
1975 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1976 && bb->succ && bb->succ->succ_next
1977 && any_condjump_p (BB_END (bb)))
1979 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability)
1981 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1982 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1986 for (e = bb->succ; e; e = e->succ_next)
1988 if (e->flags & EDGE_FALLTHRU)
1990 n_fallthru++, fallthru = e;
1991 if ((e->flags & EDGE_CROSSING)
1992 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1993 && e->src != ENTRY_BLOCK_PTR
1994 && e->dest != EXIT_BLOCK_PTR))
1996 error ("Fallthru edge crosses section boundary (bb %i)",
2002 if ((e->flags & ~(EDGE_DFS_BACK
2004 | EDGE_IRREDUCIBLE_LOOP
2005 | EDGE_LOOP_EXIT)) == 0)
2008 if (e->flags & EDGE_ABNORMAL_CALL)
2011 if (e->flags & EDGE_EH)
2013 else if (e->flags & EDGE_ABNORMAL)
2017 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2018 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2020 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2024 && (!JUMP_P (BB_END (bb))
2025 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2026 || any_condjump_p (BB_END (bb))))))
2028 error ("Too many outgoing branch edges from bb %i", bb->index);
2031 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2033 error ("Fallthru edge after unconditional jump %i", bb->index);
2036 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2038 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2041 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2042 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2044 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2047 if (n_call && !CALL_P (BB_END (bb)))
2049 error ("Call edges for non-call insn in bb %i", bb->index);
2053 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2054 && (!JUMP_P (BB_END (bb))
2055 || any_condjump_p (BB_END (bb))
2056 || any_uncondjump_p (BB_END (bb))))
2058 error ("Abnormal edges for no purpose in bb %i", bb->index);
2062 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2063 if (BLOCK_FOR_INSN (x) != bb)
2066 if (! BLOCK_FOR_INSN (x))
2068 ("insn %d inside basic block %d but block_for_insn is NULL",
2069 INSN_UID (x), bb->index);
2072 ("insn %d inside basic block %d but block_for_insn is %i",
2073 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2078 /* OK pointers are correct. Now check the header of basic
2079 block. It ought to contain optional CODE_LABEL followed
2080 by NOTE_BASIC_BLOCK. */
2084 if (BB_END (bb) == x)
2086 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2094 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2096 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2101 if (BB_END (bb) == x)
2102 /* Do checks for empty blocks her. e */
2105 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2107 if (NOTE_INSN_BASIC_BLOCK_P (x))
2109 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2110 INSN_UID (x), bb->index);
2114 if (x == BB_END (bb))
2117 if (control_flow_insn_p (x))
2119 error ("in basic block %d:", bb->index);
2120 fatal_insn ("flow control insn inside a basic block", x);
2130 /* Verify the CFG and RTL consistency common for both underlying RTL and
2133 Currently it does following checks:
2134 - all checks of rtl_verify_flow_info_1
2135 - check that all insns are in the basic blocks
2136 (except the switch handling code, barriers and notes)
2137 - check that all returns are followed by barriers
2138 - check that all fallthru edge points to the adjacent blocks. */
2140 rtl_verify_flow_info (void)
2143 int err = rtl_verify_flow_info_1 ();
2146 const rtx rtx_first = get_insns ();
2147 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2149 FOR_EACH_BB_REVERSE (bb)
2152 for (e = bb->succ; e; e = e->succ_next)
2153 if (e->flags & EDGE_FALLTHRU)
2159 /* Ensure existence of barrier in BB with no fallthru edges. */
2160 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2161 insn = NEXT_INSN (insn))
2164 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2166 error ("missing barrier after block %i", bb->index);
2171 else if (e->src != ENTRY_BLOCK_PTR
2172 && e->dest != EXIT_BLOCK_PTR)
2176 if (e->src->next_bb != e->dest)
2179 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2180 e->src->index, e->dest->index);
2184 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2185 insn = NEXT_INSN (insn))
2186 if (BARRIER_P (insn)
2187 #ifndef CASE_DROPS_THROUGH
2190 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2194 error ("verify_flow_info: Incorrect fallthru %i->%i",
2195 e->src->index, e->dest->index);
2196 fatal_insn ("wrong insn in the fallthru edge", insn);
2203 last_bb_seen = ENTRY_BLOCK_PTR;
2205 for (x = rtx_first; x; x = NEXT_INSN (x))
2207 if (NOTE_INSN_BASIC_BLOCK_P (x))
2209 bb = NOTE_BASIC_BLOCK (x);
2212 if (bb != last_bb_seen->next_bb)
2213 internal_error ("basic blocks not laid down consecutively");
2215 curr_bb = last_bb_seen = bb;
2220 switch (GET_CODE (x))
2227 /* An addr_vec is placed outside any basic block. */
2229 && JUMP_P (NEXT_INSN (x))
2230 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2231 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2234 /* But in any case, non-deletable labels can appear anywhere. */
2238 fatal_insn ("insn outside basic block", x);
2244 && returnjump_p (x) && ! condjump_p (x)
2245 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2246 fatal_insn ("return not followed by barrier", x);
2247 if (curr_bb && x == BB_END (curr_bb))
2251 if (num_bb_notes != n_basic_blocks)
2253 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2254 num_bb_notes, n_basic_blocks);
2259 /* Assume that the preceding pass has possibly eliminated jump instructions
2260 or converted the unconditional jumps. Eliminate the edges from CFG.
2261 Return true if any edges are eliminated. */
2264 purge_dead_edges (basic_block bb)
2267 rtx insn = BB_END (bb), note;
2268 bool purged = false;
2270 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2271 if (NONJUMP_INSN_P (insn)
2272 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2276 if (! may_trap_p (PATTERN (insn))
2277 || ((eqnote = find_reg_equal_equiv_note (insn))
2278 && ! may_trap_p (XEXP (eqnote, 0))))
2279 remove_note (insn, note);
2282 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2283 for (e = bb->succ; e; e = next)
2285 next = e->succ_next;
2286 if (e->flags & EDGE_EH)
2288 if (can_throw_internal (BB_END (bb)))
2291 else if (e->flags & EDGE_ABNORMAL_CALL)
2293 if (CALL_P (BB_END (bb))
2294 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2295 || INTVAL (XEXP (note, 0)) >= 0))
2302 bb->flags |= BB_DIRTY;
2311 /* We do care only about conditional jumps and simplejumps. */
2312 if (!any_condjump_p (insn)
2313 && !returnjump_p (insn)
2314 && !simplejump_p (insn))
2317 /* Branch probability/prediction notes are defined only for
2318 condjumps. We've possibly turned condjump into simplejump. */
2319 if (simplejump_p (insn))
2321 note = find_reg_note (insn, REG_BR_PROB, NULL);
2323 remove_note (insn, note);
2324 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2325 remove_note (insn, note);
2328 for (e = bb->succ; e; e = next)
2330 next = e->succ_next;
2332 /* Avoid abnormal flags to leak from computed jumps turned
2333 into simplejumps. */
2335 e->flags &= ~EDGE_ABNORMAL;
2337 /* See if this edge is one we should keep. */
2338 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2339 /* A conditional jump can fall through into the next
2340 block, so we should keep the edge. */
2342 else if (e->dest != EXIT_BLOCK_PTR
2343 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2344 /* If the destination block is the target of the jump,
2347 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2348 /* If the destination block is the exit block, and this
2349 instruction is a return, then keep the edge. */
2351 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2352 /* Keep the edges that correspond to exceptions thrown by
2353 this instruction and rematerialize the EDGE_ABNORMAL
2354 flag we just cleared above. */
2356 e->flags |= EDGE_ABNORMAL;
2360 /* We do not need this edge. */
2361 bb->flags |= BB_DIRTY;
2366 if (!bb->succ || !purged)
2370 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2375 /* Redistribute probabilities. */
2376 if (!bb->succ->succ_next)
2378 bb->succ->probability = REG_BR_PROB_BASE;
2379 bb->succ->count = bb->count;
2383 note = find_reg_note (insn, REG_BR_PROB, NULL);
2387 b = BRANCH_EDGE (bb);
2388 f = FALLTHRU_EDGE (bb);
2389 b->probability = INTVAL (XEXP (note, 0));
2390 f->probability = REG_BR_PROB_BASE - b->probability;
2391 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2392 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2397 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2399 /* First, there should not be any EH or ABCALL edges resulting
2400 from non-local gotos and the like. If there were, we shouldn't
2401 have created the sibcall in the first place. Second, there
2402 should of course never have been a fallthru edge. */
2403 if (!bb->succ || bb->succ->succ_next)
2405 if (bb->succ->flags != (EDGE_SIBCALL | EDGE_ABNORMAL))
2411 /* If we don't see a jump insn, we don't know exactly why the block would
2412 have been broken at this point. Look for a simple, non-fallthru edge,
2413 as these are only created by conditional branches. If we find such an
2414 edge we know that there used to be a jump here and can then safely
2415 remove all non-fallthru edges. */
2416 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
2423 for (e = bb->succ; e; e = next)
2425 next = e->succ_next;
2426 if (!(e->flags & EDGE_FALLTHRU))
2428 bb->flags |= BB_DIRTY;
2434 if (!bb->succ || bb->succ->succ_next)
2437 bb->succ->probability = REG_BR_PROB_BASE;
2438 bb->succ->count = bb->count;
2441 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2446 /* Search all basic blocks for potentially dead edges and purge them. Return
2447 true if some edge has been eliminated. */
2450 purge_all_dead_edges (int update_life_p)
2458 blocks = sbitmap_alloc (last_basic_block);
2459 sbitmap_zero (blocks);
2464 bool purged_here = purge_dead_edges (bb);
2466 purged |= purged_here;
2467 if (purged_here && update_life_p)
2468 SET_BIT (blocks, bb->index);
2471 if (update_life_p && purged)
2472 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2473 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2474 | PROP_KILL_DEAD_CODE);
2477 sbitmap_free (blocks);
2481 /* Same as split_block but update cfg_layout structures. */
2484 cfg_layout_split_block (basic_block bb, void *insnp)
2487 basic_block new_bb = rtl_split_block (bb, insn);
2489 new_bb->rbi->footer = bb->rbi->footer;
2490 bb->rbi->footer = NULL;
2496 /* Redirect Edge to DEST. */
2498 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2500 basic_block src = e->src;
2503 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2506 if (e->dest == dest)
2509 if (e->src != ENTRY_BLOCK_PTR
2510 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2512 src->flags |= BB_DIRTY;
2516 if (e->src == ENTRY_BLOCK_PTR
2517 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2520 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2521 e->src->index, dest->index);
2523 e->src->flags |= BB_DIRTY;
2524 redirect_edge_succ (e, dest);
2528 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2529 in the case the basic block appears to be in sequence. Avoid this
2532 if (e->flags & EDGE_FALLTHRU)
2534 /* Redirect any branch edges unified with the fallthru one. */
2535 if (JUMP_P (BB_END (src))
2536 && label_is_jump_target_p (BB_HEAD (e->dest),
2540 fprintf (dump_file, "Fallthru edge unified with branch "
2541 "%i->%i redirected to %i\n",
2542 e->src->index, e->dest->index, dest->index);
2543 e->flags &= ~EDGE_FALLTHRU;
2544 if (!redirect_branch_edge (e, dest))
2546 e->flags |= EDGE_FALLTHRU;
2547 e->src->flags |= BB_DIRTY;
2550 /* In case we are redirecting fallthru edge to the branch edge
2551 of conditional jump, remove it. */
2552 if (src->succ->succ_next
2553 && !src->succ->succ_next->succ_next)
2555 edge s = e->succ_next ? e->succ_next : src->succ;
2557 && any_condjump_p (BB_END (src))
2558 && onlyjump_p (BB_END (src)))
2559 delete_insn (BB_END (src));
2561 ret = redirect_edge_succ_nodup (e, dest);
2563 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2564 e->src->index, e->dest->index, dest->index);
2567 ret = redirect_branch_edge (e, dest);
2569 /* We don't want simplejumps in the insn stream during cfglayout. */
2570 if (simplejump_p (BB_END (src)))
2573 src->flags |= BB_DIRTY;
2577 /* Simple wrapper as we always can redirect fallthru edges. */
2579 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2581 if (!cfg_layout_redirect_edge_and_branch (e, dest))
2586 /* Same as delete_basic_block but update cfg_layout structures. */
2589 cfg_layout_delete_block (basic_block bb)
2591 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2593 if (bb->rbi->header)
2595 next = BB_HEAD (bb);
2597 NEXT_INSN (prev) = bb->rbi->header;
2599 set_first_insn (bb->rbi->header);
2600 PREV_INSN (bb->rbi->header) = prev;
2601 insn = bb->rbi->header;
2602 while (NEXT_INSN (insn))
2603 insn = NEXT_INSN (insn);
2604 NEXT_INSN (insn) = next;
2605 PREV_INSN (next) = insn;
2607 next = NEXT_INSN (BB_END (bb));
2608 if (bb->rbi->footer)
2610 insn = bb->rbi->footer;
2613 if (BARRIER_P (insn))
2615 if (PREV_INSN (insn))
2616 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2618 bb->rbi->footer = NEXT_INSN (insn);
2619 if (NEXT_INSN (insn))
2620 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2624 insn = NEXT_INSN (insn);
2626 if (bb->rbi->footer)
2629 NEXT_INSN (insn) = bb->rbi->footer;
2630 PREV_INSN (bb->rbi->footer) = insn;
2631 while (NEXT_INSN (insn))
2632 insn = NEXT_INSN (insn);
2633 NEXT_INSN (insn) = next;
2635 PREV_INSN (next) = insn;
2637 set_last_insn (insn);
2640 if (bb->next_bb != EXIT_BLOCK_PTR)
2641 to = &bb->next_bb->rbi->header;
2643 to = &cfg_layout_function_footer;
2644 rtl_delete_block (bb);
2647 prev = NEXT_INSN (prev);
2649 prev = get_insns ();
2651 next = PREV_INSN (next);
2653 next = get_last_insn ();
2655 if (next && NEXT_INSN (next) != prev)
2657 remaints = unlink_insn_chain (prev, next);
2659 while (NEXT_INSN (insn))
2660 insn = NEXT_INSN (insn);
2661 NEXT_INSN (insn) = *to;
2663 PREV_INSN (*to) = insn;
2668 /* Return true when blocks A and B can be safely merged. */
2670 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2672 /* If we are partitioning hot/cold basic blocks, we don't want to
2673 mess up unconditional or indirect jumps that cross between hot
2676 ??? If two basic blocks could otherwise be merged (which implies
2677 that the jump between the two is unconditional), and one is in a
2678 hot section and the other is in a cold section, surely that means
2679 that one of the section choices is wrong. */
2681 if (flag_reorder_blocks_and_partition
2682 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2683 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2684 || BB_PARTITION (a) != BB_PARTITION (b)))
2687 /* There must be exactly one edge in between the blocks. */
2688 return (a->succ && !a->succ->succ_next && a->succ->dest == b
2689 && !b->pred->pred_next && a != b
2690 /* Must be simple edge. */
2691 && !(a->succ->flags & EDGE_COMPLEX)
2692 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2693 /* If the jump insn has side effects,
2694 we can't kill the edge. */
2695 && (!JUMP_P (BB_END (a))
2696 || (reload_completed
2697 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2700 /* Merge block A and B, abort when it is not possible. */
2702 cfg_layout_merge_blocks (basic_block a, basic_block b)
2704 #ifdef ENABLE_CHECKING
2705 if (!cfg_layout_can_merge_blocks_p (a, b))
2709 /* If there was a CODE_LABEL beginning B, delete it. */
2710 if (LABEL_P (BB_HEAD (b)))
2711 delete_insn (BB_HEAD (b));
2713 /* We should have fallthru edge in a, or we can do dummy redirection to get
2715 if (JUMP_P (BB_END (a)))
2716 try_redirect_by_replacing_jump (a->succ, b, true);
2717 if (JUMP_P (BB_END (a)))
2720 /* Possible line number notes should appear in between. */
2723 rtx first = BB_END (a), last;
2725 last = emit_insn_after (b->rbi->header, BB_END (a));
2726 delete_insn_chain (NEXT_INSN (first), last);
2727 b->rbi->header = NULL;
2730 /* In the case basic blocks are not adjacent, move them around. */
2731 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2733 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2735 emit_insn_after (first, BB_END (a));
2736 /* Skip possible DELETED_LABEL insn. */
2737 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2738 first = NEXT_INSN (first);
2739 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2742 delete_insn (first);
2744 /* Otherwise just re-associate the instructions. */
2749 for (insn = BB_HEAD (b);
2750 insn != NEXT_INSN (BB_END (b));
2751 insn = NEXT_INSN (insn))
2752 set_block_for_insn (insn, a);
2754 /* Skip possible DELETED_LABEL insn. */
2755 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2756 insn = NEXT_INSN (insn);
2757 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2760 BB_END (a) = BB_END (b);
2764 /* Possible tablejumps and barriers should appear after the block. */
2767 if (!a->rbi->footer)
2768 a->rbi->footer = b->rbi->footer;
2771 rtx last = a->rbi->footer;
2773 while (NEXT_INSN (last))
2774 last = NEXT_INSN (last);
2775 NEXT_INSN (last) = b->rbi->footer;
2776 PREV_INSN (b->rbi->footer) = last;
2778 b->rbi->footer = NULL;
2782 fprintf (dump_file, "Merged blocks %d and %d.\n",
2783 a->index, b->index);
2789 cfg_layout_split_edge (edge e)
2792 basic_block new_bb =
2793 create_basic_block (e->src != ENTRY_BLOCK_PTR
2794 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2797 /* ??? This info is likely going to be out of date very soon, but we must
2798 create it to avoid getting an ICE later. */
2799 if (e->dest->global_live_at_start)
2801 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2802 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2803 COPY_REG_SET (new_bb->global_live_at_start,
2804 e->dest->global_live_at_start);
2805 COPY_REG_SET (new_bb->global_live_at_end,
2806 e->dest->global_live_at_start);
2809 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2810 redirect_edge_and_branch_force (e, new_bb);
2815 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2818 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2822 /* Return 1 if BB ends with a call, possibly followed by some
2823 instructions that must stay with the call, 0 otherwise. */
2826 rtl_block_ends_with_call_p (basic_block bb)
2828 rtx insn = BB_END (bb);
2830 while (!CALL_P (insn)
2831 && insn != BB_HEAD (bb)
2832 && keep_with_call_p (insn))
2833 insn = PREV_INSN (insn);
2834 return (CALL_P (insn));
2837 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2840 rtl_block_ends_with_condjump_p (basic_block bb)
2842 return any_condjump_p (BB_END (bb));
2845 /* Return true if we need to add fake edge to exit.
2846 Helper function for rtl_flow_call_edges_add. */
2849 need_fake_edge_p (rtx insn)
2855 && !SIBLING_CALL_P (insn)
2856 && !find_reg_note (insn, REG_NORETURN, NULL)
2857 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2858 && !CONST_OR_PURE_CALL_P (insn)))
2861 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2862 && MEM_VOLATILE_P (PATTERN (insn)))
2863 || (GET_CODE (PATTERN (insn)) == PARALLEL
2864 && asm_noperands (insn) != -1
2865 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2866 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2869 /* Add fake edges to the function exit for any non constant and non noreturn
2870 calls, volatile inline assembly in the bitmap of blocks specified by
2871 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2874 The goal is to expose cases in which entering a basic block does not imply
2875 that all subsequent instructions must be executed. */
2878 rtl_flow_call_edges_add (sbitmap blocks)
2881 int blocks_split = 0;
2882 int last_bb = last_basic_block;
2883 bool check_last_block = false;
2885 if (n_basic_blocks == 0)
2889 check_last_block = true;
2891 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2893 /* In the last basic block, before epilogue generation, there will be
2894 a fallthru edge to EXIT. Special care is required if the last insn
2895 of the last basic block is a call because make_edge folds duplicate
2896 edges, which would result in the fallthru edge also being marked
2897 fake, which would result in the fallthru edge being removed by
2898 remove_fake_edges, which would result in an invalid CFG.
2900 Moreover, we can't elide the outgoing fake edge, since the block
2901 profiler needs to take this into account in order to solve the minimal
2902 spanning tree in the case that the call doesn't return.
2904 Handle this by adding a dummy instruction in a new last basic block. */
2905 if (check_last_block)
2907 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2908 rtx insn = BB_END (bb);
2910 /* Back up past insns that must be kept in the same block as a call. */
2911 while (insn != BB_HEAD (bb)
2912 && keep_with_call_p (insn))
2913 insn = PREV_INSN (insn);
2915 if (need_fake_edge_p (insn))
2919 for (e = bb->succ; e; e = e->succ_next)
2920 if (e->dest == EXIT_BLOCK_PTR)
2922 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2923 commit_edge_insertions ();
2929 /* Now add fake edges to the function exit for any non constant
2930 calls since there is no way that we can determine if they will
2933 for (i = 0; i < last_bb; i++)
2935 basic_block bb = BASIC_BLOCK (i);
2942 if (blocks && !TEST_BIT (blocks, i))
2945 for (insn = BB_END (bb); ; insn = prev_insn)
2947 prev_insn = PREV_INSN (insn);
2948 if (need_fake_edge_p (insn))
2951 rtx split_at_insn = insn;
2953 /* Don't split the block between a call and an insn that should
2954 remain in the same block as the call. */
2956 while (split_at_insn != BB_END (bb)
2957 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2958 split_at_insn = NEXT_INSN (split_at_insn);
2960 /* The handling above of the final block before the epilogue
2961 should be enough to verify that there is no edge to the exit
2962 block in CFG already. Calling make_edge in such case would
2963 cause us to mark that edge as fake and remove it later. */
2965 #ifdef ENABLE_CHECKING
2966 if (split_at_insn == BB_END (bb))
2967 for (e = bb->succ; e; e = e->succ_next)
2968 if (e->dest == EXIT_BLOCK_PTR)
2972 /* Note that the following may create a new basic block
2973 and renumber the existing basic blocks. */
2974 if (split_at_insn != BB_END (bb))
2976 e = split_block (bb, split_at_insn);
2981 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2984 if (insn == BB_HEAD (bb))
2990 verify_flow_info ();
2992 return blocks_split;
2995 /* Implementation of CFG manipulation for linearized RTL. */
2996 struct cfg_hooks rtl_cfg_hooks = {
2998 rtl_verify_flow_info,
3000 rtl_create_basic_block,
3001 rtl_redirect_edge_and_branch,
3002 rtl_redirect_edge_and_branch_force,
3005 rtl_move_block_after,
3006 rtl_can_merge_blocks, /* can_merge_blocks_p */
3010 NULL, /* can_duplicate_block_p */
3011 NULL, /* duplicate_block */
3013 rtl_make_forwarder_block,
3014 rtl_tidy_fallthru_edge,
3015 rtl_block_ends_with_call_p,
3016 rtl_block_ends_with_condjump_p,
3017 rtl_flow_call_edges_add
3020 /* Implementation of CFG manipulation for cfg layout RTL, where
3021 basic block connected via fallthru edges does not have to be adjacent.
3022 This representation will hopefully become the default one in future
3023 version of the compiler. */
3025 /* We do not want to declare these functions in a header file, since they
3026 should only be used through the cfghooks interface, and we do not want to
3027 move them here since it would require also moving quite a lot of related
3029 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3030 extern basic_block cfg_layout_duplicate_bb (basic_block);
3032 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3034 rtl_verify_flow_info_1,
3036 cfg_layout_create_basic_block,
3037 cfg_layout_redirect_edge_and_branch,
3038 cfg_layout_redirect_edge_and_branch_force,
3039 cfg_layout_delete_block,
3040 cfg_layout_split_block,
3041 rtl_move_block_after,
3042 cfg_layout_can_merge_blocks_p,
3043 cfg_layout_merge_blocks,
3046 cfg_layout_can_duplicate_bb_p,
3047 cfg_layout_duplicate_bb,
3048 cfg_layout_split_edge,
3049 rtl_make_forwarder_block,
3051 rtl_block_ends_with_call_p,
3052 rtl_block_ends_with_condjump_p,
3053 rtl_flow_call_edges_add