1 /* Control flow graph manipulation code for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, 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 #include "tree-pass.h"
64 static int can_delete_note_p (rtx);
65 static int can_delete_label_p (rtx);
66 static void commit_one_edge_insertion (edge, int);
67 static basic_block rtl_split_edge (edge);
68 static bool rtl_move_block_after (basic_block, basic_block);
69 static int rtl_verify_flow_info (void);
70 static basic_block cfg_layout_split_block (basic_block, void *);
71 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
72 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
73 static void cfg_layout_delete_block (basic_block);
74 static void rtl_delete_block (basic_block);
75 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
76 static edge rtl_redirect_edge_and_branch (edge, basic_block);
77 static basic_block rtl_split_block (basic_block, void *);
78 static void rtl_dump_bb (basic_block, FILE *, int);
79 static int rtl_verify_flow_info_1 (void);
80 static void rtl_make_forwarder_block (edge);
82 /* Return true if NOTE is not one of the ones that must be kept paired,
83 so that we may simply delete it. */
86 can_delete_note_p (rtx note)
88 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
89 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
92 /* True if a given label can be deleted. */
95 can_delete_label_p (rtx label)
97 return (!LABEL_PRESERVE_P (label)
98 /* User declared labels must be preserved. */
99 && LABEL_NAME (label) == 0
100 && !in_expr_list_p (forced_labels, label));
103 /* Delete INSN by patching it out. Return the next insn. */
106 delete_insn (rtx insn)
108 rtx next = NEXT_INSN (insn);
110 bool really_delete = true;
114 /* Some labels can't be directly removed from the INSN chain, as they
115 might be references via variables, constant pool etc.
116 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
117 if (! can_delete_label_p (insn))
119 const char *name = LABEL_NAME (insn);
121 really_delete = false;
122 PUT_CODE (insn, NOTE);
123 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
124 NOTE_DELETED_LABEL_NAME (insn) = name;
127 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
132 /* If this insn has already been deleted, something is very wrong. */
133 gcc_assert (!INSN_DELETED_P (insn));
135 INSN_DELETED_P (insn) = 1;
138 /* If deleting a jump, decrement the use count of the label. Deleting
139 the label itself should happen in the normal course of block merging. */
142 && LABEL_P (JUMP_LABEL (insn)))
143 LABEL_NUSES (JUMP_LABEL (insn))--;
145 /* Also if deleting an insn that references a label. */
148 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
149 && LABEL_P (XEXP (note, 0)))
151 LABEL_NUSES (XEXP (note, 0))--;
152 remove_note (insn, note);
157 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
158 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
160 rtx pat = PATTERN (insn);
161 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
162 int len = XVECLEN (pat, diff_vec_p);
165 for (i = 0; i < len; i++)
167 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
169 /* When deleting code in bulk (e.g. removing many unreachable
170 blocks) we can delete a label that's a target of the vector
171 before deleting the vector itself. */
173 LABEL_NUSES (label)--;
180 /* Like delete_insn but also purge dead edges from BB. */
182 delete_insn_and_edges (rtx insn)
188 && BLOCK_FOR_INSN (insn)
189 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
191 x = delete_insn (insn);
193 purge_dead_edges (BLOCK_FOR_INSN (insn));
197 /* Unlink a chain of insns between START and FINISH, leaving notes
198 that must be paired. */
201 delete_insn_chain (rtx start, rtx finish)
205 /* Unchain the insns one by one. It would be quicker to delete all of these
206 with a single unchaining, rather than one at a time, but we need to keep
210 next = NEXT_INSN (start);
211 if (NOTE_P (start) && !can_delete_note_p (start))
214 next = delete_insn (start);
222 /* Like delete_insn but also purge dead edges from BB. */
224 delete_insn_chain_and_edges (rtx first, rtx last)
229 && BLOCK_FOR_INSN (last)
230 && BB_END (BLOCK_FOR_INSN (last)) == last)
232 delete_insn_chain (first, last);
234 purge_dead_edges (BLOCK_FOR_INSN (last));
237 /* Create a new basic block consisting of the instructions between HEAD and END
238 inclusive. This function is designed to allow fast BB construction - reuses
239 the note and basic block struct in BB_NOTE, if any and do not grow
240 BASIC_BLOCK chain and should be used directly only by CFG construction code.
241 END can be NULL in to create new empty basic block before HEAD. Both END
242 and HEAD can be NULL to create basic block at the end of INSN chain.
243 AFTER is the basic block we should be put after. */
246 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
251 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
254 /* If we found an existing note, thread it back onto the chain. */
262 after = PREV_INSN (head);
266 if (after != bb_note && NEXT_INSN (after) != bb_note)
267 reorder_insns_nobb (bb_note, bb_note, after);
271 /* Otherwise we must create a note and a basic block structure. */
275 init_rtl_bb_info (bb);
278 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
279 else if (LABEL_P (head) && end)
281 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
287 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
293 NOTE_BASIC_BLOCK (bb_note) = bb;
296 /* Always include the bb note in the block. */
297 if (NEXT_INSN (end) == bb_note)
302 bb->index = last_basic_block++;
303 bb->flags = BB_NEW | BB_RTL;
304 link_block (bb, after);
305 SET_BASIC_BLOCK (bb->index, bb);
306 update_bb_for_insn (bb);
307 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
309 /* Tag the block so that we know it has been used when considering
310 other basic block notes. */
316 /* Create new basic block consisting of instructions in between HEAD and END
317 and place it to the BB chain after block AFTER. END can be NULL in to
318 create new empty basic block before HEAD. Both END and HEAD can be NULL to
319 create basic block at the end of INSN chain. */
322 rtl_create_basic_block (void *headp, void *endp, basic_block after)
324 rtx head = headp, end = endp;
327 /* Grow the basic block array if needed. */
328 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info))
330 size_t old_size = VEC_length (basic_block, basic_block_info);
331 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
333 VEC_safe_grow (basic_block, gc, basic_block_info, new_size);
334 p = VEC_address (basic_block, basic_block_info);
335 memset (&p[old_size], 0, sizeof (basic_block) * (new_size - old_size));
340 bb = create_basic_block_structure (head, end, NULL, after);
346 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
348 basic_block newbb = rtl_create_basic_block (head, end, after);
353 /* Delete the insns in a (non-live) block. We physically delete every
354 non-deleted-note insn, and update the flow graph appropriately.
356 Return nonzero if we deleted an exception handler. */
358 /* ??? Preserving all such notes strikes me as wrong. It would be nice
359 to post-process the stream to remove empty blocks, loops, ranges, etc. */
362 rtl_delete_block (basic_block b)
366 /* If the head of this block is a CODE_LABEL, then it might be the
367 label for an exception handler which can't be reached. We need
368 to remove the label from the exception_handler_label list. */
371 maybe_remove_eh_handler (insn);
373 /* Include any jump table following the basic block. */
375 if (tablejump_p (end, NULL, &tmp))
378 /* Include any barriers that may follow the basic block. */
379 tmp = next_nonnote_insn (end);
380 while (tmp && BARRIER_P (tmp))
383 tmp = next_nonnote_insn (end);
386 /* Selectively delete the entire chain. */
388 delete_insn_chain (insn, end);
389 if (b->il.rtl->global_live_at_start)
391 FREE_REG_SET (b->il.rtl->global_live_at_start);
392 FREE_REG_SET (b->il.rtl->global_live_at_end);
393 b->il.rtl->global_live_at_start = NULL;
394 b->il.rtl->global_live_at_end = NULL;
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;
431 struct tree_opt_pass pass_free_cfg =
435 free_bb_for_insn, /* execute */
438 0, /* static_pass_number */
440 0, /* properties_required */
441 0, /* properties_provided */
442 PROP_cfg, /* properties_destroyed */
443 0, /* todo_flags_start */
444 0, /* todo_flags_finish */
448 /* Return RTX to emit after when we want to emit code on the entry of function. */
450 entry_of_function (void)
452 return (n_basic_blocks > NUM_FIXED_BLOCKS ?
453 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
456 /* Emit INSN at the entry point of the function, ensuring that it is only
457 executed once per function. */
459 emit_insn_at_entry (rtx insn)
461 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs);
462 edge e = ei_safe_edge (ei);
463 if (!(e->flags & EDGE_FALLTHRU))
466 insert_insn_on_edge (insn, e);
467 commit_edge_insertions ();
470 /* Update insns block within BB. */
473 update_bb_for_insn (basic_block bb)
477 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
479 if (!BARRIER_P (insn))
480 set_block_for_insn (insn, bb);
481 if (insn == BB_END (bb))
486 /* Creates a new basic block just after basic block B by splitting
487 everything after specified instruction I. */
490 rtl_split_block (basic_block bb, void *insnp)
499 insn = first_insn_after_basic_block_note (bb);
502 insn = PREV_INSN (insn);
504 insn = get_last_insn ();
507 /* We probably should check type of the insn so that we do not create
508 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
510 if (insn == BB_END (bb))
511 emit_note_after (NOTE_INSN_DELETED, insn);
513 /* Create the new basic block. */
514 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
515 BB_COPY_PARTITION (new_bb, bb);
518 /* Redirect the outgoing edges. */
519 new_bb->succs = bb->succs;
521 FOR_EACH_EDGE (e, ei, new_bb->succs)
524 if (bb->il.rtl->global_live_at_start)
526 new_bb->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
527 new_bb->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
528 COPY_REG_SET (new_bb->il.rtl->global_live_at_end, bb->il.rtl->global_live_at_end);
530 /* We now have to calculate which registers are live at the end
531 of the split basic block and at the start of the new basic
532 block. Start with those registers that are known to be live
533 at the end of the original basic block and get
534 propagate_block to determine which registers are live. */
535 COPY_REG_SET (new_bb->il.rtl->global_live_at_start, bb->il.rtl->global_live_at_end);
536 propagate_block (new_bb, new_bb->il.rtl->global_live_at_start, NULL, NULL, 0);
537 COPY_REG_SET (bb->il.rtl->global_live_at_end,
538 new_bb->il.rtl->global_live_at_start);
539 #ifdef HAVE_conditional_execution
540 /* In the presence of conditional execution we are not able to update
541 liveness precisely. */
542 if (reload_completed)
544 bb->flags |= BB_DIRTY;
545 new_bb->flags |= BB_DIRTY;
553 /* Blocks A and B are to be merged into a single block A. The insns
554 are already contiguous. */
557 rtl_merge_blocks (basic_block a, basic_block b)
559 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
560 rtx del_first = NULL_RTX, del_last = NULL_RTX;
563 /* If there was a CODE_LABEL beginning B, delete it. */
564 if (LABEL_P (b_head))
566 /* This might have been an EH label that no longer has incoming
567 EH edges. Update data structures to match. */
568 maybe_remove_eh_handler (b_head);
570 /* Detect basic blocks with nothing but a label. This can happen
571 in particular at the end of a function. */
575 del_first = del_last = b_head;
576 b_head = NEXT_INSN (b_head);
579 /* Delete the basic block note and handle blocks containing just that
581 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
589 b_head = NEXT_INSN (b_head);
592 /* If there was a jump out of A, delete it. */
597 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
599 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
600 || prev == BB_HEAD (a))
606 /* If this was a conditional jump, we need to also delete
607 the insn that set cc0. */
608 if (only_sets_cc0_p (prev))
612 prev = prev_nonnote_insn (prev);
619 a_end = PREV_INSN (del_first);
621 else if (BARRIER_P (NEXT_INSN (a_end)))
622 del_first = NEXT_INSN (a_end);
624 /* Delete everything marked above as well as crap that might be
625 hanging out between the two blocks. */
627 delete_insn_chain (del_first, del_last);
629 /* Reassociate the insns of B with A. */
634 for (x = a_end; x != b_end; x = NEXT_INSN (x))
635 set_block_for_insn (x, a);
637 set_block_for_insn (b_end, a);
643 a->il.rtl->global_live_at_end = b->il.rtl->global_live_at_end;
646 /* Return true when block A and B can be merged. */
648 rtl_can_merge_blocks (basic_block a,basic_block b)
650 /* If we are partitioning hot/cold basic blocks, we don't want to
651 mess up unconditional or indirect jumps that cross between hot
654 Basic block partitioning may result in some jumps that appear to
655 be optimizable (or blocks that appear to be mergeable), but which really
656 must be left untouched (they are required to make it safely across
657 partition boundaries). See the comments at the top of
658 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
660 if (BB_PARTITION (a) != BB_PARTITION (b))
663 /* There must be exactly one edge in between the blocks. */
664 return (single_succ_p (a)
665 && single_succ (a) == b
668 /* Must be simple edge. */
669 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
671 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
672 /* If the jump insn has side effects,
673 we can't kill the edge. */
674 && (!JUMP_P (BB_END (a))
676 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
679 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
683 block_label (basic_block block)
685 if (block == EXIT_BLOCK_PTR)
688 if (!LABEL_P (BB_HEAD (block)))
690 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
693 return BB_HEAD (block);
696 /* Attempt to perform edge redirection by replacing possibly complex jump
697 instruction by unconditional jump or removing jump completely. This can
698 apply only if all edges now point to the same block. The parameters and
699 return values are equivalent to redirect_edge_and_branch. */
702 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
704 basic_block src = e->src;
705 rtx insn = BB_END (src), kill_from;
709 /* If we are partitioning hot/cold basic blocks, we don't want to
710 mess up unconditional or indirect jumps that cross between hot
713 Basic block partitioning may result in some jumps that appear to
714 be optimizable (or blocks that appear to be mergeable), but which really
715 must be left untouched (they are required to make it safely across
716 partition boundaries). See the comments at the top of
717 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
719 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
720 || BB_PARTITION (src) != BB_PARTITION (target))
723 /* We can replace or remove a complex jump only when we have exactly
724 two edges. Also, if we have exactly one outgoing edge, we can
726 if (EDGE_COUNT (src->succs) >= 3
727 /* Verify that all targets will be TARGET. Specifically, the
728 edge that is not E must also go to TARGET. */
729 || (EDGE_COUNT (src->succs) == 2
730 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
733 if (!onlyjump_p (insn))
735 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
738 /* Avoid removing branch with side effects. */
739 set = single_set (insn);
740 if (!set || side_effects_p (set))
743 /* In case we zap a conditional jump, we'll need to kill
744 the cc0 setter too. */
747 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
748 kill_from = PREV_INSN (insn);
751 /* See if we can create the fallthru edge. */
752 if (in_cfglayout || can_fallthru (src, target))
755 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
758 /* Selectively unlink whole insn chain. */
761 rtx insn = src->il.rtl->footer;
763 delete_insn_chain (kill_from, BB_END (src));
765 /* Remove barriers but keep jumptables. */
768 if (BARRIER_P (insn))
770 if (PREV_INSN (insn))
771 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
773 src->il.rtl->footer = NEXT_INSN (insn);
774 if (NEXT_INSN (insn))
775 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
779 insn = NEXT_INSN (insn);
783 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
786 /* If this already is simplejump, redirect it. */
787 else if (simplejump_p (insn))
789 if (e->dest == target)
792 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
793 INSN_UID (insn), e->dest->index, target->index);
794 if (!redirect_jump (insn, block_label (target), 0))
796 gcc_assert (target == EXIT_BLOCK_PTR);
801 /* Cannot do anything for target exit block. */
802 else if (target == EXIT_BLOCK_PTR)
805 /* Or replace possibly complicated jump insn by simple jump insn. */
808 rtx target_label = block_label (target);
809 rtx barrier, label, table;
811 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
812 JUMP_LABEL (BB_END (src)) = target_label;
813 LABEL_NUSES (target_label)++;
815 fprintf (dump_file, "Replacing insn %i by jump %i\n",
816 INSN_UID (insn), INSN_UID (BB_END (src)));
819 delete_insn_chain (kill_from, insn);
821 /* Recognize a tablejump that we are converting to a
822 simple jump and remove its associated CODE_LABEL
823 and ADDR_VEC or ADDR_DIFF_VEC. */
824 if (tablejump_p (insn, &label, &table))
825 delete_insn_chain (label, table);
827 barrier = next_nonnote_insn (BB_END (src));
828 if (!barrier || !BARRIER_P (barrier))
829 emit_barrier_after (BB_END (src));
832 if (barrier != NEXT_INSN (BB_END (src)))
834 /* Move the jump before barrier so that the notes
835 which originally were or were created before jump table are
836 inside the basic block. */
837 rtx new_insn = BB_END (src);
840 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
841 tmp = NEXT_INSN (tmp))
842 set_block_for_insn (tmp, src);
844 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
845 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
847 NEXT_INSN (new_insn) = barrier;
848 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
850 PREV_INSN (new_insn) = PREV_INSN (barrier);
851 PREV_INSN (barrier) = new_insn;
856 /* Keep only one edge out and set proper flags. */
857 if (!single_succ_p (src))
859 gcc_assert (single_succ_p (src));
861 e = single_succ_edge (src);
863 e->flags = EDGE_FALLTHRU;
867 e->probability = REG_BR_PROB_BASE;
868 e->count = src->count;
870 /* We don't want a block to end on a line-number note since that has
871 the potential of changing the code between -g and not -g. */
872 while (NOTE_P (BB_END (e->src))
873 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
874 delete_insn (BB_END (e->src));
876 if (e->dest != target)
877 redirect_edge_succ (e, target);
882 /* Redirect edge representing branch of (un)conditional jump or tablejump,
885 redirect_branch_edge (edge e, basic_block target)
888 rtx old_label = BB_HEAD (e->dest);
889 basic_block src = e->src;
890 rtx insn = BB_END (src);
892 /* We can only redirect non-fallthru edges of jump insn. */
893 if (e->flags & EDGE_FALLTHRU)
895 else if (!JUMP_P (insn))
898 /* Recognize a tablejump and adjust all matching cases. */
899 if (tablejump_p (insn, NULL, &tmp))
903 rtx new_label = block_label (target);
905 if (target == EXIT_BLOCK_PTR)
907 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
908 vec = XVEC (PATTERN (tmp), 0);
910 vec = XVEC (PATTERN (tmp), 1);
912 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
913 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
915 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
916 --LABEL_NUSES (old_label);
917 ++LABEL_NUSES (new_label);
920 /* Handle casesi dispatch insns. */
921 if ((tmp = single_set (insn)) != NULL
922 && SET_DEST (tmp) == pc_rtx
923 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
924 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
925 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
927 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
929 --LABEL_NUSES (old_label);
930 ++LABEL_NUSES (new_label);
935 /* ?? We may play the games with moving the named labels from
936 one basic block to the other in case only one computed_jump is
938 if (computed_jump_p (insn)
939 /* A return instruction can't be redirected. */
940 || returnjump_p (insn))
943 /* If the insn doesn't go where we think, we're confused. */
944 gcc_assert (JUMP_LABEL (insn) == old_label);
946 /* If the substitution doesn't succeed, die. This can happen
947 if the back end emitted unrecognizable instructions or if
948 target is exit block on some arches. */
949 if (!redirect_jump (insn, block_label (target), 0))
951 gcc_assert (target == EXIT_BLOCK_PTR);
957 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
958 e->src->index, e->dest->index, target->index);
960 if (e->dest != target)
961 e = redirect_edge_succ_nodup (e, target);
965 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
966 expense of adding new instructions or reordering basic blocks.
968 Function can be also called with edge destination equivalent to the TARGET.
969 Then it should try the simplifications and do nothing if none is possible.
971 Return edge representing the branch if transformation succeeded. Return NULL
973 We still return NULL in case E already destinated TARGET and we didn't
974 managed to simplify instruction stream. */
977 rtl_redirect_edge_and_branch (edge e, basic_block target)
980 basic_block src = e->src;
982 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
985 if (e->dest == target)
988 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
990 src->flags |= BB_DIRTY;
994 ret = redirect_branch_edge (e, target);
998 src->flags |= BB_DIRTY;
1002 /* Like force_nonfallthru below, but additionally performs redirection
1003 Used by redirect_edge_and_branch_force. */
1006 force_nonfallthru_and_redirect (edge e, basic_block target)
1008 basic_block jump_block, new_bb = NULL, src = e->src;
1011 int abnormal_edge_flags = 0;
1013 /* In the case the last instruction is conditional jump to the next
1014 instruction, first redirect the jump itself and then continue
1015 by creating a basic block afterwards to redirect fallthru edge. */
1016 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1017 && any_condjump_p (BB_END (e->src))
1018 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1021 edge b = unchecked_make_edge (e->src, target, 0);
1024 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1025 gcc_assert (redirected);
1027 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1030 int prob = INTVAL (XEXP (note, 0));
1032 b->probability = prob;
1033 b->count = e->count * prob / REG_BR_PROB_BASE;
1034 e->probability -= e->probability;
1035 e->count -= b->count;
1036 if (e->probability < 0)
1043 if (e->flags & EDGE_ABNORMAL)
1045 /* Irritating special case - fallthru edge to the same block as abnormal
1047 We can't redirect abnormal edge, but we still can split the fallthru
1048 one and create separate abnormal edge to original destination.
1049 This allows bb-reorder to make such edge non-fallthru. */
1050 gcc_assert (e->dest == target);
1051 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1052 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1056 gcc_assert (e->flags & EDGE_FALLTHRU);
1057 if (e->src == ENTRY_BLOCK_PTR)
1059 /* We can't redirect the entry block. Create an empty block
1060 at the start of the function which we use to add the new
1066 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1068 /* Change the existing edge's source to be the new block, and add
1069 a new edge from the entry block to the new block. */
1071 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1075 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1085 VEC_safe_push (edge, gc, bb->succs, e);
1086 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1090 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1092 /* Create the new structures. */
1094 /* If the old block ended with a tablejump, skip its table
1095 by searching forward from there. Otherwise start searching
1096 forward from the last instruction of the old block. */
1097 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1098 note = BB_END (e->src);
1099 note = NEXT_INSN (note);
1101 jump_block = create_basic_block (note, NULL, e->src);
1102 jump_block->count = e->count;
1103 jump_block->frequency = EDGE_FREQUENCY (e);
1104 jump_block->loop_depth = target->loop_depth;
1106 if (target->il.rtl->global_live_at_start)
1108 jump_block->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
1109 jump_block->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
1110 COPY_REG_SET (jump_block->il.rtl->global_live_at_start,
1111 target->il.rtl->global_live_at_start);
1112 COPY_REG_SET (jump_block->il.rtl->global_live_at_end,
1113 target->il.rtl->global_live_at_start);
1116 /* Make sure new block ends up in correct hot/cold section. */
1118 BB_COPY_PARTITION (jump_block, e->src);
1119 if (flag_reorder_blocks_and_partition
1120 && targetm.have_named_sections
1121 && JUMP_P (BB_END (jump_block))
1122 && !any_condjump_p (BB_END (jump_block))
1123 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1124 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP,
1131 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1132 new_edge->probability = e->probability;
1133 new_edge->count = e->count;
1135 /* Redirect old edge. */
1136 redirect_edge_pred (e, jump_block);
1137 e->probability = REG_BR_PROB_BASE;
1139 new_bb = jump_block;
1142 jump_block = e->src;
1144 e->flags &= ~EDGE_FALLTHRU;
1145 if (target == EXIT_BLOCK_PTR)
1148 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1155 rtx label = block_label (target);
1156 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1157 JUMP_LABEL (BB_END (jump_block)) = label;
1158 LABEL_NUSES (label)++;
1161 emit_barrier_after (BB_END (jump_block));
1162 redirect_edge_succ_nodup (e, target);
1164 if (abnormal_edge_flags)
1165 make_edge (src, target, abnormal_edge_flags);
1170 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1171 (and possibly create new basic block) to make edge non-fallthru.
1172 Return newly created BB or NULL if none. */
1175 force_nonfallthru (edge e)
1177 return force_nonfallthru_and_redirect (e, e->dest);
1180 /* Redirect edge even at the expense of creating new jump insn or
1181 basic block. Return new basic block if created, NULL otherwise.
1182 Conversion must be possible. */
1185 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1187 if (redirect_edge_and_branch (e, target)
1188 || e->dest == target)
1191 /* In case the edge redirection failed, try to force it to be non-fallthru
1192 and redirect newly created simplejump. */
1193 e->src->flags |= BB_DIRTY;
1194 return force_nonfallthru_and_redirect (e, target);
1197 /* The given edge should potentially be a fallthru edge. If that is in
1198 fact true, delete the jump and barriers that are in the way. */
1201 rtl_tidy_fallthru_edge (edge e)
1204 basic_block b = e->src, c = b->next_bb;
1206 /* ??? In a late-running flow pass, other folks may have deleted basic
1207 blocks by nopping out blocks, leaving multiple BARRIERs between here
1208 and the target label. They ought to be chastised and fixed.
1210 We can also wind up with a sequence of undeletable labels between
1211 one block and the next.
1213 So search through a sequence of barriers, labels, and notes for
1214 the head of block C and assert that we really do fall through. */
1216 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1220 /* Remove what will soon cease being the jump insn from the source block.
1221 If block B consisted only of this single jump, turn it into a deleted
1226 && (any_uncondjump_p (q)
1227 || single_succ_p (b)))
1230 /* If this was a conditional jump, we need to also delete
1231 the insn that set cc0. */
1232 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1238 /* We don't want a block to end on a line-number note since that has
1239 the potential of changing the code between -g and not -g. */
1240 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1244 /* Selectively unlink the sequence. */
1245 if (q != PREV_INSN (BB_HEAD (c)))
1246 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1248 e->flags |= EDGE_FALLTHRU;
1251 /* Should move basic block BB after basic block AFTER. NIY. */
1254 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1255 basic_block after ATTRIBUTE_UNUSED)
1260 /* Split a (typically critical) edge. Return the new block.
1261 The edge must not be abnormal.
1263 ??? The code generally expects to be called on critical edges.
1264 The case of a block ending in an unconditional jump to a
1265 block with multiple predecessors is not handled optimally. */
1268 rtl_split_edge (edge edge_in)
1273 /* Abnormal edges cannot be split. */
1274 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1276 /* We are going to place the new block in front of edge destination.
1277 Avoid existence of fallthru predecessors. */
1278 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1283 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1284 if (e->flags & EDGE_FALLTHRU)
1288 force_nonfallthru (e);
1291 /* Create the basic block note. */
1292 if (edge_in->dest != EXIT_BLOCK_PTR)
1293 before = BB_HEAD (edge_in->dest);
1297 /* If this is a fall through edge to the exit block, the blocks might be
1298 not adjacent, and the right place is the after the source. */
1299 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1301 before = NEXT_INSN (BB_END (edge_in->src));
1302 bb = create_basic_block (before, NULL, edge_in->src);
1303 BB_COPY_PARTITION (bb, edge_in->src);
1307 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1308 /* ??? Why not edge_in->dest->prev_bb here? */
1309 BB_COPY_PARTITION (bb, edge_in->dest);
1312 /* ??? This info is likely going to be out of date very soon. */
1313 if (edge_in->dest->il.rtl->global_live_at_start)
1315 bb->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
1316 bb->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
1317 COPY_REG_SET (bb->il.rtl->global_live_at_start,
1318 edge_in->dest->il.rtl->global_live_at_start);
1319 COPY_REG_SET (bb->il.rtl->global_live_at_end,
1320 edge_in->dest->il.rtl->global_live_at_start);
1323 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1325 /* For non-fallthru edges, we must adjust the predecessor's
1326 jump instruction to target our new block. */
1327 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1329 edge redirected = redirect_edge_and_branch (edge_in, bb);
1330 gcc_assert (redirected);
1333 redirect_edge_succ (edge_in, bb);
1338 /* Queue instructions for insertion on an edge between two basic blocks.
1339 The new instructions and basic blocks (if any) will not appear in the
1340 CFG until commit_edge_insertions is called. */
1343 insert_insn_on_edge (rtx pattern, edge e)
1345 /* We cannot insert instructions on an abnormal critical edge.
1346 It will be easier to find the culprit if we die now. */
1347 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1349 if (e->insns.r == NULL_RTX)
1352 push_to_sequence (e->insns.r);
1354 emit_insn (pattern);
1356 e->insns.r = get_insns ();
1360 /* Update the CFG for the instructions queued on edge E. */
1363 commit_one_edge_insertion (edge e, int watch_calls)
1365 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1366 basic_block bb = NULL;
1368 /* Pull the insns off the edge now since the edge might go away. */
1370 e->insns.r = NULL_RTX;
1372 /* Special case -- avoid inserting code between call and storing
1373 its return value. */
1374 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1375 && single_pred_p (e->dest)
1376 && e->src != ENTRY_BLOCK_PTR
1377 && CALL_P (BB_END (e->src)))
1379 rtx next = next_nonnote_insn (BB_END (e->src));
1381 after = BB_HEAD (e->dest);
1382 /* The first insn after the call may be a stack pop, skip it. */
1384 && keep_with_call_p (next))
1387 next = next_nonnote_insn (next);
1391 if (!before && !after)
1393 /* Figure out where to put these things. If the destination has
1394 one predecessor, insert there. Except for the exit block. */
1395 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1399 /* Get the location correct wrt a code label, and "nice" wrt
1400 a basic block note, and before everything else. */
1403 tmp = NEXT_INSN (tmp);
1404 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1405 tmp = NEXT_INSN (tmp);
1406 if (tmp == BB_HEAD (bb))
1409 after = PREV_INSN (tmp);
1411 after = get_last_insn ();
1414 /* If the source has one successor and the edge is not abnormal,
1415 insert there. Except for the entry block. */
1416 else if ((e->flags & EDGE_ABNORMAL) == 0
1417 && single_succ_p (e->src)
1418 && e->src != ENTRY_BLOCK_PTR)
1422 /* It is possible to have a non-simple jump here. Consider a target
1423 where some forms of unconditional jumps clobber a register. This
1424 happens on the fr30 for example.
1426 We know this block has a single successor, so we can just emit
1427 the queued insns before the jump. */
1428 if (JUMP_P (BB_END (bb)))
1429 before = BB_END (bb);
1432 /* We'd better be fallthru, or we've lost track of
1434 gcc_assert (e->flags & EDGE_FALLTHRU);
1436 after = BB_END (bb);
1439 /* Otherwise we must split the edge. */
1442 bb = split_edge (e);
1443 after = BB_END (bb);
1445 if (flag_reorder_blocks_and_partition
1446 && targetm.have_named_sections
1447 && e->src != ENTRY_BLOCK_PTR
1448 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1449 && !(e->flags & EDGE_CROSSING))
1451 rtx bb_note, cur_insn;
1454 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1455 cur_insn = NEXT_INSN (cur_insn))
1456 if (NOTE_P (cur_insn)
1457 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1463 if (JUMP_P (BB_END (bb))
1464 && !any_condjump_p (BB_END (bb))
1465 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1466 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1467 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1472 /* Now that we've found the spot, do the insertion. */
1476 emit_insn_before_noloc (insns, before);
1477 last = prev_nonnote_insn (before);
1480 last = emit_insn_after_noloc (insns, after);
1482 if (returnjump_p (last))
1484 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1485 This is not currently a problem because this only happens
1486 for the (single) epilogue, which already has a fallthru edge
1489 e = single_succ_edge (bb);
1490 gcc_assert (e->dest == EXIT_BLOCK_PTR
1491 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1493 e->flags &= ~EDGE_FALLTHRU;
1494 emit_barrier_after (last);
1497 delete_insn (before);
1500 gcc_assert (!JUMP_P (last));
1502 /* Mark the basic block for find_many_sub_basic_blocks. */
1506 /* Update the CFG for all queued instructions. */
1509 commit_edge_insertions (void)
1513 bool changed = false;
1515 #ifdef ENABLE_CHECKING
1516 verify_flow_info ();
1519 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1524 FOR_EACH_EDGE (e, ei, bb->succs)
1528 commit_one_edge_insertion (e, false);
1535 blocks = sbitmap_alloc (last_basic_block);
1536 sbitmap_zero (blocks);
1540 SET_BIT (blocks, bb->index);
1541 /* Check for forgotten bb->aux values before commit_edge_insertions
1543 gcc_assert (bb->aux == &bb->aux);
1546 find_many_sub_basic_blocks (blocks);
1547 sbitmap_free (blocks);
1550 /* Update the CFG for all queued instructions, taking special care of inserting
1551 code on edges between call and storing its return value. */
1554 commit_edge_insertions_watch_calls (void)
1558 bool changed = false;
1560 #ifdef ENABLE_CHECKING
1561 verify_flow_info ();
1564 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1569 FOR_EACH_EDGE (e, ei, bb->succs)
1573 commit_one_edge_insertion (e, true);
1580 blocks = sbitmap_alloc (last_basic_block);
1581 sbitmap_zero (blocks);
1585 SET_BIT (blocks, bb->index);
1586 /* Check for forgotten bb->aux values before commit_edge_insertions
1588 gcc_assert (bb->aux == &bb->aux);
1591 find_many_sub_basic_blocks (blocks);
1592 sbitmap_free (blocks);
1595 /* Print out RTL-specific basic block information (live information
1596 at start and end). */
1599 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1605 s_indent = alloca ((size_t) indent + 1);
1606 memset (s_indent, ' ', (size_t) indent);
1607 s_indent[indent] = '\0';
1609 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1610 dump_regset (bb->il.rtl->global_live_at_start, outf);
1613 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1614 insn = NEXT_INSN (insn))
1615 print_rtl_single (outf, insn);
1617 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1618 dump_regset (bb->il.rtl->global_live_at_end, outf);
1622 /* Like print_rtl, but also print out live information for the start of each
1626 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1631 fprintf (outf, "(nil)\n");
1634 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1635 int max_uid = get_max_uid ();
1636 basic_block *start = XCNEWVEC (basic_block, max_uid);
1637 basic_block *end = XCNEWVEC (basic_block, max_uid);
1638 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1642 FOR_EACH_BB_REVERSE (bb)
1646 start[INSN_UID (BB_HEAD (bb))] = bb;
1647 end[INSN_UID (BB_END (bb))] = bb;
1648 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1650 enum bb_state state = IN_MULTIPLE_BB;
1652 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1654 in_bb_p[INSN_UID (x)] = state;
1656 if (x == BB_END (bb))
1661 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1665 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1667 fprintf (outf, ";; Start of basic block %d, registers live:",
1669 dump_regset (bb->il.rtl->global_live_at_start, outf);
1673 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1674 && !NOTE_P (tmp_rtx)
1675 && !BARRIER_P (tmp_rtx))
1676 fprintf (outf, ";; Insn is not within a basic block\n");
1677 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1678 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1680 did_output = print_rtl_single (outf, tmp_rtx);
1682 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1684 fprintf (outf, ";; End of basic block %d, registers live:\n",
1686 dump_regset (bb->il.rtl->global_live_at_end, outf);
1699 if (current_function_epilogue_delay_list != 0)
1701 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1702 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1703 tmp_rtx = XEXP (tmp_rtx, 1))
1704 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1709 update_br_prob_note (basic_block bb)
1712 if (!JUMP_P (BB_END (bb)))
1714 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1715 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1717 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1720 /* Verify the CFG and RTL consistency common for both underlying RTL and
1723 Currently it does following checks:
1725 - test head/end pointers
1726 - overlapping of basic blocks
1727 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1728 - tails of basic blocks (ensure that boundary is necessary)
1729 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1730 and NOTE_INSN_BASIC_BLOCK
1731 - verify that no fall_thru edge crosses hot/cold partition boundaries
1733 In future it can be extended check a lot of other stuff as well
1734 (reachability of basic blocks, life information, etc. etc.). */
1737 rtl_verify_flow_info_1 (void)
1739 const int max_uid = get_max_uid ();
1740 rtx last_head = get_last_insn ();
1741 basic_block *bb_info;
1746 bb_info = XCNEWVEC (basic_block, max_uid);
1748 FOR_EACH_BB_REVERSE (bb)
1750 rtx head = BB_HEAD (bb);
1751 rtx end = BB_END (bb);
1753 /* Verify the end of the basic block is in the INSN chain. */
1754 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1758 if (!(bb->flags & BB_RTL))
1760 error ("BB_RTL flag not set for block %d", bb->index);
1766 error ("end insn %d for block %d not found in the insn stream",
1767 INSN_UID (end), bb->index);
1771 /* Work backwards from the end to the head of the basic block
1772 to verify the head is in the RTL chain. */
1773 for (; x != NULL_RTX; x = PREV_INSN (x))
1775 /* While walking over the insn chain, verify insns appear
1776 in only one basic block and initialize the BB_INFO array
1777 used by other passes. */
1778 if (bb_info[INSN_UID (x)] != NULL)
1780 error ("insn %d is in multiple basic blocks (%d and %d)",
1781 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1785 bb_info[INSN_UID (x)] = bb;
1792 error ("head insn %d for block %d not found in the insn stream",
1793 INSN_UID (head), bb->index);
1800 /* Now check the basic blocks (boundaries etc.) */
1801 FOR_EACH_BB_REVERSE (bb)
1803 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1804 edge e, fallthru = NULL;
1808 if (JUMP_P (BB_END (bb))
1809 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1810 && EDGE_COUNT (bb->succs) >= 2
1811 && any_condjump_p (BB_END (bb)))
1813 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1814 && profile_status != PROFILE_ABSENT)
1816 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1817 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1821 FOR_EACH_EDGE (e, ei, bb->succs)
1823 if (e->flags & EDGE_FALLTHRU)
1825 n_fallthru++, fallthru = e;
1826 if ((e->flags & EDGE_CROSSING)
1827 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1828 && e->src != ENTRY_BLOCK_PTR
1829 && e->dest != EXIT_BLOCK_PTR))
1831 error ("fallthru edge crosses section boundary (bb %i)",
1837 if ((e->flags & ~(EDGE_DFS_BACK
1839 | EDGE_IRREDUCIBLE_LOOP
1841 | EDGE_CROSSING)) == 0)
1844 if (e->flags & EDGE_ABNORMAL_CALL)
1847 if (e->flags & EDGE_EH)
1849 else if (e->flags & EDGE_ABNORMAL)
1853 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
1854 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1856 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1860 && (!JUMP_P (BB_END (bb))
1861 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1862 || any_condjump_p (BB_END (bb))))))
1864 error ("too many outgoing branch edges from bb %i", bb->index);
1867 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1869 error ("fallthru edge after unconditional jump %i", bb->index);
1872 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1874 error ("wrong amount of branch edges after unconditional jump %i", bb->index);
1877 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1878 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1880 error ("wrong amount of branch edges after conditional jump %i",
1884 if (n_call && !CALL_P (BB_END (bb)))
1886 error ("call edges for non-call insn in bb %i", bb->index);
1890 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1891 && (!JUMP_P (BB_END (bb))
1892 || any_condjump_p (BB_END (bb))
1893 || any_uncondjump_p (BB_END (bb))))
1895 error ("abnormal edges for no purpose in bb %i", bb->index);
1899 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1900 /* We may have a barrier inside a basic block before dead code
1901 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1902 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1905 if (! BLOCK_FOR_INSN (x))
1907 ("insn %d inside basic block %d but block_for_insn is NULL",
1908 INSN_UID (x), bb->index);
1911 ("insn %d inside basic block %d but block_for_insn is %i",
1912 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1917 /* OK pointers are correct. Now check the header of basic
1918 block. It ought to contain optional CODE_LABEL followed
1919 by NOTE_BASIC_BLOCK. */
1923 if (BB_END (bb) == x)
1925 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1933 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1935 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1940 if (BB_END (bb) == x)
1941 /* Do checks for empty blocks here. */
1944 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1946 if (NOTE_INSN_BASIC_BLOCK_P (x))
1948 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1949 INSN_UID (x), bb->index);
1953 if (x == BB_END (bb))
1956 if (control_flow_insn_p (x))
1958 error ("in basic block %d:", bb->index);
1959 fatal_insn ("flow control insn inside a basic block", x);
1969 /* Verify the CFG and RTL consistency common for both underlying RTL and
1972 Currently it does following checks:
1973 - all checks of rtl_verify_flow_info_1
1974 - check that all insns are in the basic blocks
1975 (except the switch handling code, barriers and notes)
1976 - check that all returns are followed by barriers
1977 - check that all fallthru edge points to the adjacent blocks. */
1979 rtl_verify_flow_info (void)
1982 int err = rtl_verify_flow_info_1 ();
1985 const rtx rtx_first = get_insns ();
1986 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
1988 FOR_EACH_BB_REVERSE (bb)
1993 if (bb->predictions)
1995 error ("bb prediction set for block %i, but it is not used in RTL land", bb->index);
1999 FOR_EACH_EDGE (e, ei, bb->succs)
2000 if (e->flags & EDGE_FALLTHRU)
2006 /* Ensure existence of barrier in BB with no fallthru edges. */
2007 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2008 insn = NEXT_INSN (insn))
2011 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2013 error ("missing barrier after block %i", bb->index);
2018 else if (e->src != ENTRY_BLOCK_PTR
2019 && e->dest != EXIT_BLOCK_PTR)
2023 if (e->src->next_bb != e->dest)
2026 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2027 e->src->index, e->dest->index);
2031 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2032 insn = NEXT_INSN (insn))
2033 if (BARRIER_P (insn) || INSN_P (insn))
2035 error ("verify_flow_info: Incorrect fallthru %i->%i",
2036 e->src->index, e->dest->index);
2037 fatal_insn ("wrong insn in the fallthru edge", insn);
2044 last_bb_seen = ENTRY_BLOCK_PTR;
2046 for (x = rtx_first; x; x = NEXT_INSN (x))
2048 if (NOTE_INSN_BASIC_BLOCK_P (x))
2050 bb = NOTE_BASIC_BLOCK (x);
2053 if (bb != last_bb_seen->next_bb)
2054 internal_error ("basic blocks not laid down consecutively");
2056 curr_bb = last_bb_seen = bb;
2061 switch (GET_CODE (x))
2068 /* An addr_vec is placed outside any basic block. */
2070 && JUMP_P (NEXT_INSN (x))
2071 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2072 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2075 /* But in any case, non-deletable labels can appear anywhere. */
2079 fatal_insn ("insn outside basic block", x);
2084 && returnjump_p (x) && ! condjump_p (x)
2085 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2086 fatal_insn ("return not followed by barrier", x);
2087 if (curr_bb && x == BB_END (curr_bb))
2091 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2093 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2094 num_bb_notes, n_basic_blocks);
2099 /* Assume that the preceding pass has possibly eliminated jump instructions
2100 or converted the unconditional jumps. Eliminate the edges from CFG.
2101 Return true if any edges are eliminated. */
2104 purge_dead_edges (basic_block bb)
2107 rtx insn = BB_END (bb), note;
2108 bool purged = false;
2112 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2113 if (NONJUMP_INSN_P (insn)
2114 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2118 if (! may_trap_p (PATTERN (insn))
2119 || ((eqnote = find_reg_equal_equiv_note (insn))
2120 && ! may_trap_p (XEXP (eqnote, 0))))
2121 remove_note (insn, note);
2124 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2125 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2127 /* There are three types of edges we need to handle correctly here: EH
2128 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2129 latter can appear when nonlocal gotos are used. */
2130 if (e->flags & EDGE_EH)
2132 if (can_throw_internal (BB_END (bb))
2133 /* If this is a call edge, verify that this is a call insn. */
2134 && (! (e->flags & EDGE_ABNORMAL_CALL)
2135 || CALL_P (BB_END (bb))))
2141 else if (e->flags & EDGE_ABNORMAL_CALL)
2143 if (CALL_P (BB_END (bb))
2144 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2145 || INTVAL (XEXP (note, 0)) >= 0))
2158 bb->flags |= BB_DIRTY;
2168 /* We do care only about conditional jumps and simplejumps. */
2169 if (!any_condjump_p (insn)
2170 && !returnjump_p (insn)
2171 && !simplejump_p (insn))
2174 /* Branch probability/prediction notes are defined only for
2175 condjumps. We've possibly turned condjump into simplejump. */
2176 if (simplejump_p (insn))
2178 note = find_reg_note (insn, REG_BR_PROB, NULL);
2180 remove_note (insn, note);
2181 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2182 remove_note (insn, note);
2185 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2187 /* Avoid abnormal flags to leak from computed jumps turned
2188 into simplejumps. */
2190 e->flags &= ~EDGE_ABNORMAL;
2192 /* See if this edge is one we should keep. */
2193 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2194 /* A conditional jump can fall through into the next
2195 block, so we should keep the edge. */
2200 else if (e->dest != EXIT_BLOCK_PTR
2201 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2202 /* If the destination block is the target of the jump,
2208 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2209 /* If the destination block is the exit block, and this
2210 instruction is a return, then keep the edge. */
2215 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2216 /* Keep the edges that correspond to exceptions thrown by
2217 this instruction and rematerialize the EDGE_ABNORMAL
2218 flag we just cleared above. */
2220 e->flags |= EDGE_ABNORMAL;
2225 /* We do not need this edge. */
2226 bb->flags |= BB_DIRTY;
2231 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2235 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2240 /* Redistribute probabilities. */
2241 if (single_succ_p (bb))
2243 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2244 single_succ_edge (bb)->count = bb->count;
2248 note = find_reg_note (insn, REG_BR_PROB, NULL);
2252 b = BRANCH_EDGE (bb);
2253 f = FALLTHRU_EDGE (bb);
2254 b->probability = INTVAL (XEXP (note, 0));
2255 f->probability = REG_BR_PROB_BASE - b->probability;
2256 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2257 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2262 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2264 /* First, there should not be any EH or ABCALL edges resulting
2265 from non-local gotos and the like. If there were, we shouldn't
2266 have created the sibcall in the first place. Second, there
2267 should of course never have been a fallthru edge. */
2268 gcc_assert (single_succ_p (bb));
2269 gcc_assert (single_succ_edge (bb)->flags
2270 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2275 /* If we don't see a jump insn, we don't know exactly why the block would
2276 have been broken at this point. Look for a simple, non-fallthru edge,
2277 as these are only created by conditional branches. If we find such an
2278 edge we know that there used to be a jump here and can then safely
2279 remove all non-fallthru edges. */
2281 FOR_EACH_EDGE (e, ei, bb->succs)
2282 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2291 /* Remove all but the fake and fallthru edges. The fake edge may be
2292 the only successor for this block in the case of noreturn
2294 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2296 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2298 bb->flags |= BB_DIRTY;
2306 gcc_assert (single_succ_p (bb));
2308 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2309 single_succ_edge (bb)->count = bb->count;
2312 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2317 /* Search all basic blocks for potentially dead edges and purge them. Return
2318 true if some edge has been eliminated. */
2321 purge_all_dead_edges (void)
2328 bool purged_here = purge_dead_edges (bb);
2330 purged |= purged_here;
2336 /* Same as split_block but update cfg_layout structures. */
2339 cfg_layout_split_block (basic_block bb, void *insnp)
2342 basic_block new_bb = rtl_split_block (bb, insn);
2344 new_bb->il.rtl->footer = bb->il.rtl->footer;
2345 bb->il.rtl->footer = NULL;
2351 /* Redirect Edge to DEST. */
2353 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2355 basic_block src = e->src;
2358 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2361 if (e->dest == dest)
2364 if (e->src != ENTRY_BLOCK_PTR
2365 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2367 src->flags |= BB_DIRTY;
2371 if (e->src == ENTRY_BLOCK_PTR
2372 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2375 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2376 e->src->index, dest->index);
2378 e->src->flags |= BB_DIRTY;
2379 redirect_edge_succ (e, dest);
2383 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2384 in the case the basic block appears to be in sequence. Avoid this
2387 if (e->flags & EDGE_FALLTHRU)
2389 /* Redirect any branch edges unified with the fallthru one. */
2390 if (JUMP_P (BB_END (src))
2391 && label_is_jump_target_p (BB_HEAD (e->dest),
2397 fprintf (dump_file, "Fallthru edge unified with branch "
2398 "%i->%i redirected to %i\n",
2399 e->src->index, e->dest->index, dest->index);
2400 e->flags &= ~EDGE_FALLTHRU;
2401 redirected = redirect_branch_edge (e, dest);
2402 gcc_assert (redirected);
2403 e->flags |= EDGE_FALLTHRU;
2404 e->src->flags |= BB_DIRTY;
2407 /* In case we are redirecting fallthru edge to the branch edge
2408 of conditional jump, remove it. */
2409 if (EDGE_COUNT (src->succs) == 2)
2411 /* Find the edge that is different from E. */
2412 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2415 && any_condjump_p (BB_END (src))
2416 && onlyjump_p (BB_END (src)))
2417 delete_insn (BB_END (src));
2419 ret = redirect_edge_succ_nodup (e, dest);
2421 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2422 e->src->index, e->dest->index, dest->index);
2425 ret = redirect_branch_edge (e, dest);
2427 /* We don't want simplejumps in the insn stream during cfglayout. */
2428 gcc_assert (!simplejump_p (BB_END (src)));
2430 src->flags |= BB_DIRTY;
2434 /* Simple wrapper as we always can redirect fallthru edges. */
2436 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2438 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2440 gcc_assert (redirected);
2444 /* Same as delete_basic_block but update cfg_layout structures. */
2447 cfg_layout_delete_block (basic_block bb)
2449 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2451 if (bb->il.rtl->header)
2453 next = BB_HEAD (bb);
2455 NEXT_INSN (prev) = bb->il.rtl->header;
2457 set_first_insn (bb->il.rtl->header);
2458 PREV_INSN (bb->il.rtl->header) = prev;
2459 insn = bb->il.rtl->header;
2460 while (NEXT_INSN (insn))
2461 insn = NEXT_INSN (insn);
2462 NEXT_INSN (insn) = next;
2463 PREV_INSN (next) = insn;
2465 next = NEXT_INSN (BB_END (bb));
2466 if (bb->il.rtl->footer)
2468 insn = bb->il.rtl->footer;
2471 if (BARRIER_P (insn))
2473 if (PREV_INSN (insn))
2474 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2476 bb->il.rtl->footer = NEXT_INSN (insn);
2477 if (NEXT_INSN (insn))
2478 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2482 insn = NEXT_INSN (insn);
2484 if (bb->il.rtl->footer)
2487 NEXT_INSN (insn) = bb->il.rtl->footer;
2488 PREV_INSN (bb->il.rtl->footer) = insn;
2489 while (NEXT_INSN (insn))
2490 insn = NEXT_INSN (insn);
2491 NEXT_INSN (insn) = next;
2493 PREV_INSN (next) = insn;
2495 set_last_insn (insn);
2498 if (bb->next_bb != EXIT_BLOCK_PTR)
2499 to = &bb->next_bb->il.rtl->header;
2501 to = &cfg_layout_function_footer;
2503 rtl_delete_block (bb);
2506 prev = NEXT_INSN (prev);
2508 prev = get_insns ();
2510 next = PREV_INSN (next);
2512 next = get_last_insn ();
2514 if (next && NEXT_INSN (next) != prev)
2516 remaints = unlink_insn_chain (prev, next);
2518 while (NEXT_INSN (insn))
2519 insn = NEXT_INSN (insn);
2520 NEXT_INSN (insn) = *to;
2522 PREV_INSN (*to) = insn;
2527 /* Return true when blocks A and B can be safely merged. */
2529 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2531 /* If we are partitioning hot/cold basic blocks, we don't want to
2532 mess up unconditional or indirect jumps that cross between hot
2535 Basic block partitioning may result in some jumps that appear to
2536 be optimizable (or blocks that appear to be mergeable), but which really
2537 must be left untouched (they are required to make it safely across
2538 partition boundaries). See the comments at the top of
2539 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2541 if (BB_PARTITION (a) != BB_PARTITION (b))
2544 /* There must be exactly one edge in between the blocks. */
2545 return (single_succ_p (a)
2546 && single_succ (a) == b
2547 && single_pred_p (b) == 1
2549 /* Must be simple edge. */
2550 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2551 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2552 /* If the jump insn has side effects,
2553 we can't kill the edge. */
2554 && (!JUMP_P (BB_END (a))
2555 || (reload_completed
2556 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2559 /* Merge block A and B. The blocks must be mergeable. */
2562 cfg_layout_merge_blocks (basic_block a, basic_block b)
2564 #ifdef ENABLE_CHECKING
2565 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2568 /* If there was a CODE_LABEL beginning B, delete it. */
2569 if (LABEL_P (BB_HEAD (b)))
2571 /* This might have been an EH label that no longer has incoming
2572 EH edges. Update data structures to match. */
2573 maybe_remove_eh_handler (BB_HEAD (b));
2575 delete_insn (BB_HEAD (b));
2578 /* We should have fallthru edge in a, or we can do dummy redirection to get
2580 if (JUMP_P (BB_END (a)))
2581 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2582 gcc_assert (!JUMP_P (BB_END (a)));
2584 /* Possible line number notes should appear in between. */
2585 if (b->il.rtl->header)
2587 rtx first = BB_END (a), last;
2589 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a));
2590 delete_insn_chain (NEXT_INSN (first), last);
2591 b->il.rtl->header = NULL;
2594 /* In the case basic blocks are not adjacent, move them around. */
2595 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2597 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2599 emit_insn_after_noloc (first, BB_END (a));
2600 /* Skip possible DELETED_LABEL insn. */
2601 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2602 first = NEXT_INSN (first);
2603 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2605 delete_insn (first);
2607 /* Otherwise just re-associate the instructions. */
2612 for (insn = BB_HEAD (b);
2613 insn != NEXT_INSN (BB_END (b));
2614 insn = NEXT_INSN (insn))
2615 set_block_for_insn (insn, a);
2617 /* Skip possible DELETED_LABEL insn. */
2618 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2619 insn = NEXT_INSN (insn);
2620 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2622 BB_END (a) = BB_END (b);
2626 /* Possible tablejumps and barriers should appear after the block. */
2627 if (b->il.rtl->footer)
2629 if (!a->il.rtl->footer)
2630 a->il.rtl->footer = b->il.rtl->footer;
2633 rtx last = a->il.rtl->footer;
2635 while (NEXT_INSN (last))
2636 last = NEXT_INSN (last);
2637 NEXT_INSN (last) = b->il.rtl->footer;
2638 PREV_INSN (b->il.rtl->footer) = last;
2640 b->il.rtl->footer = NULL;
2642 a->il.rtl->global_live_at_end = b->il.rtl->global_live_at_end;
2645 fprintf (dump_file, "Merged blocks %d and %d.\n",
2646 a->index, b->index);
2652 cfg_layout_split_edge (edge e)
2654 basic_block new_bb =
2655 create_basic_block (e->src != ENTRY_BLOCK_PTR
2656 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2659 /* ??? This info is likely going to be out of date very soon, but we must
2660 create it to avoid getting an ICE later. */
2661 if (e->dest->il.rtl->global_live_at_start)
2663 new_bb->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
2664 new_bb->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
2665 COPY_REG_SET (new_bb->il.rtl->global_live_at_start,
2666 e->dest->il.rtl->global_live_at_start);
2667 COPY_REG_SET (new_bb->il.rtl->global_live_at_end,
2668 e->dest->il.rtl->global_live_at_start);
2671 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2672 redirect_edge_and_branch_force (e, new_bb);
2677 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2680 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2684 /* Return 1 if BB ends with a call, possibly followed by some
2685 instructions that must stay with the call, 0 otherwise. */
2688 rtl_block_ends_with_call_p (basic_block bb)
2690 rtx insn = BB_END (bb);
2692 while (!CALL_P (insn)
2693 && insn != BB_HEAD (bb)
2694 && keep_with_call_p (insn))
2695 insn = PREV_INSN (insn);
2696 return (CALL_P (insn));
2699 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2702 rtl_block_ends_with_condjump_p (basic_block bb)
2704 return any_condjump_p (BB_END (bb));
2707 /* Return true if we need to add fake edge to exit.
2708 Helper function for rtl_flow_call_edges_add. */
2711 need_fake_edge_p (rtx insn)
2717 && !SIBLING_CALL_P (insn)
2718 && !find_reg_note (insn, REG_NORETURN, NULL)
2719 && !CONST_OR_PURE_CALL_P (insn)))
2722 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2723 && MEM_VOLATILE_P (PATTERN (insn)))
2724 || (GET_CODE (PATTERN (insn)) == PARALLEL
2725 && asm_noperands (insn) != -1
2726 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2727 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2730 /* Add fake edges to the function exit for any non constant and non noreturn
2731 calls, volatile inline assembly in the bitmap of blocks specified by
2732 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2735 The goal is to expose cases in which entering a basic block does not imply
2736 that all subsequent instructions must be executed. */
2739 rtl_flow_call_edges_add (sbitmap blocks)
2742 int blocks_split = 0;
2743 int last_bb = last_basic_block;
2744 bool check_last_block = false;
2746 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2750 check_last_block = true;
2752 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2754 /* In the last basic block, before epilogue generation, there will be
2755 a fallthru edge to EXIT. Special care is required if the last insn
2756 of the last basic block is a call because make_edge folds duplicate
2757 edges, which would result in the fallthru edge also being marked
2758 fake, which would result in the fallthru edge being removed by
2759 remove_fake_edges, which would result in an invalid CFG.
2761 Moreover, we can't elide the outgoing fake edge, since the block
2762 profiler needs to take this into account in order to solve the minimal
2763 spanning tree in the case that the call doesn't return.
2765 Handle this by adding a dummy instruction in a new last basic block. */
2766 if (check_last_block)
2768 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2769 rtx insn = BB_END (bb);
2771 /* Back up past insns that must be kept in the same block as a call. */
2772 while (insn != BB_HEAD (bb)
2773 && keep_with_call_p (insn))
2774 insn = PREV_INSN (insn);
2776 if (need_fake_edge_p (insn))
2780 e = find_edge (bb, EXIT_BLOCK_PTR);
2783 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2784 commit_edge_insertions ();
2789 /* Now add fake edges to the function exit for any non constant
2790 calls since there is no way that we can determine if they will
2793 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
2795 basic_block bb = BASIC_BLOCK (i);
2802 if (blocks && !TEST_BIT (blocks, i))
2805 for (insn = BB_END (bb); ; insn = prev_insn)
2807 prev_insn = PREV_INSN (insn);
2808 if (need_fake_edge_p (insn))
2811 rtx split_at_insn = insn;
2813 /* Don't split the block between a call and an insn that should
2814 remain in the same block as the call. */
2816 while (split_at_insn != BB_END (bb)
2817 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2818 split_at_insn = NEXT_INSN (split_at_insn);
2820 /* The handling above of the final block before the epilogue
2821 should be enough to verify that there is no edge to the exit
2822 block in CFG already. Calling make_edge in such case would
2823 cause us to mark that edge as fake and remove it later. */
2825 #ifdef ENABLE_CHECKING
2826 if (split_at_insn == BB_END (bb))
2828 e = find_edge (bb, EXIT_BLOCK_PTR);
2829 gcc_assert (e == NULL);
2833 /* Note that the following may create a new basic block
2834 and renumber the existing basic blocks. */
2835 if (split_at_insn != BB_END (bb))
2837 e = split_block (bb, split_at_insn);
2842 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2845 if (insn == BB_HEAD (bb))
2851 verify_flow_info ();
2853 return blocks_split;
2856 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2857 the conditional branch target, SECOND_HEAD should be the fall-thru
2858 there is no need to handle this here the loop versioning code handles
2859 this. the reason for SECON_HEAD is that it is needed for condition
2860 in trees, and this should be of the same type since it is a hook. */
2862 rtl_lv_add_condition_to_bb (basic_block first_head ,
2863 basic_block second_head ATTRIBUTE_UNUSED,
2864 basic_block cond_bb, void *comp_rtx)
2866 rtx label, seq, jump;
2867 rtx op0 = XEXP ((rtx)comp_rtx, 0);
2868 rtx op1 = XEXP ((rtx)comp_rtx, 1);
2869 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
2870 enum machine_mode mode;
2873 label = block_label (first_head);
2874 mode = GET_MODE (op0);
2875 if (mode == VOIDmode)
2876 mode = GET_MODE (op1);
2879 op0 = force_operand (op0, NULL_RTX);
2880 op1 = force_operand (op1, NULL_RTX);
2881 do_compare_rtx_and_jump (op0, op1, comp, 0,
2882 mode, NULL_RTX, NULL_RTX, label);
2883 jump = get_last_insn ();
2884 JUMP_LABEL (jump) = label;
2885 LABEL_NUSES (label)++;
2889 /* Add the new cond , in the new head. */
2890 emit_insn_after(seq, BB_END(cond_bb));
2894 /* Given a block B with unconditional branch at its end, get the
2895 store the return the branch edge and the fall-thru edge in
2896 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
2898 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
2899 edge *fallthru_edge)
2901 edge e = EDGE_SUCC (b, 0);
2903 if (e->flags & EDGE_FALLTHRU)
2906 *branch_edge = EDGE_SUCC (b, 1);
2911 *fallthru_edge = EDGE_SUCC (b, 1);
2916 init_rtl_bb_info (basic_block bb)
2918 gcc_assert (!bb->il.rtl);
2919 bb->il.rtl = ggc_alloc_cleared (sizeof (struct rtl_bb_info));
2923 /* Add EXPR to the end of basic block BB. */
2926 insert_insn_end_bb_new (rtx pat, basic_block bb)
2928 rtx insn = BB_END (bb);
2932 while (NEXT_INSN (pat_end) != NULL_RTX)
2933 pat_end = NEXT_INSN (pat_end);
2935 /* If the last insn is a jump, insert EXPR in front [taking care to
2936 handle cc0, etc. properly]. Similarly we need to care trapping
2937 instructions in presence of non-call exceptions. */
2940 || (NONJUMP_INSN_P (insn)
2941 && (!single_succ_p (bb)
2942 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
2947 /* If this is a jump table, then we can't insert stuff here. Since
2948 we know the previous real insn must be the tablejump, we insert
2949 the new instruction just before the tablejump. */
2950 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
2951 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
2952 insn = prev_real_insn (insn);
2955 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
2956 if cc0 isn't set. */
2957 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
2959 insn = XEXP (note, 0);
2962 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
2963 if (maybe_cc0_setter
2964 && INSN_P (maybe_cc0_setter)
2965 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
2966 insn = maybe_cc0_setter;
2969 /* FIXME: What if something in cc0/jump uses value set in new
2971 new_insn = emit_insn_before_noloc (pat, insn);
2974 /* Likewise if the last insn is a call, as will happen in the presence
2975 of exception handling. */
2976 else if (CALL_P (insn)
2977 && (!single_succ_p (bb)
2978 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
2980 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
2981 we search backward and place the instructions before the first
2982 parameter is loaded. Do this for everyone for consistency and a
2983 presumption that we'll get better code elsewhere as well. */
2985 /* Since different machines initialize their parameter registers
2986 in different orders, assume nothing. Collect the set of all
2987 parameter registers. */
2988 insn = find_first_parameter_load (insn, BB_HEAD (bb));
2990 /* If we found all the parameter loads, then we want to insert
2991 before the first parameter load.
2993 If we did not find all the parameter loads, then we might have
2994 stopped on the head of the block, which could be a CODE_LABEL.
2995 If we inserted before the CODE_LABEL, then we would be putting
2996 the insn in the wrong basic block. In that case, put the insn
2997 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
2998 while (LABEL_P (insn)
2999 || NOTE_INSN_BASIC_BLOCK_P (insn))
3000 insn = NEXT_INSN (insn);
3002 new_insn = emit_insn_before_noloc (pat, insn);
3005 new_insn = emit_insn_after_noloc (pat, insn);
3010 /* Implementation of CFG manipulation for linearized RTL. */
3011 struct cfg_hooks rtl_cfg_hooks = {
3013 rtl_verify_flow_info,
3015 rtl_create_basic_block,
3016 rtl_redirect_edge_and_branch,
3017 rtl_redirect_edge_and_branch_force,
3020 rtl_move_block_after,
3021 rtl_can_merge_blocks, /* can_merge_blocks_p */
3025 NULL, /* can_duplicate_block_p */
3026 NULL, /* duplicate_block */
3028 rtl_make_forwarder_block,
3029 rtl_tidy_fallthru_edge,
3030 rtl_block_ends_with_call_p,
3031 rtl_block_ends_with_condjump_p,
3032 rtl_flow_call_edges_add,
3033 NULL, /* execute_on_growing_pred */
3034 NULL, /* execute_on_shrinking_pred */
3035 NULL, /* duplicate loop for trees */
3036 NULL, /* lv_add_condition_to_bb */
3037 NULL, /* lv_adjust_loop_header_phi*/
3038 NULL, /* extract_cond_bb_edges */
3039 NULL /* flush_pending_stmts */
3042 /* Implementation of CFG manipulation for cfg layout RTL, where
3043 basic block connected via fallthru edges does not have to be adjacent.
3044 This representation will hopefully become the default one in future
3045 version of the compiler. */
3047 /* We do not want to declare these functions in a header file, since they
3048 should only be used through the cfghooks interface, and we do not want to
3049 move them here since it would require also moving quite a lot of related
3051 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3052 extern basic_block cfg_layout_duplicate_bb (basic_block);
3054 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3056 rtl_verify_flow_info_1,
3058 cfg_layout_create_basic_block,
3059 cfg_layout_redirect_edge_and_branch,
3060 cfg_layout_redirect_edge_and_branch_force,
3061 cfg_layout_delete_block,
3062 cfg_layout_split_block,
3063 rtl_move_block_after,
3064 cfg_layout_can_merge_blocks_p,
3065 cfg_layout_merge_blocks,
3068 cfg_layout_can_duplicate_bb_p,
3069 cfg_layout_duplicate_bb,
3070 cfg_layout_split_edge,
3071 rtl_make_forwarder_block,
3073 rtl_block_ends_with_call_p,
3074 rtl_block_ends_with_condjump_p,
3075 rtl_flow_call_edges_add,
3076 NULL, /* execute_on_growing_pred */
3077 NULL, /* execute_on_shrinking_pred */
3078 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3079 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3080 NULL, /* lv_adjust_loop_header_phi*/
3081 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3082 NULL /* flush_pending_stmts */