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, 2006, 2007, 2008, 2009, 2010, 2011
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
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
33 - CFG fixing after coarse manipulation
36 Functions not supposed for generic use:
37 - Infrastructure to determine quickly basic block for insn
38 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
39 - Edge redirection with updating and optimizing of insn chain
40 block_label, tidy_fallthru_edge, force_nonfallthru */
44 #include "coretypes.h"
47 #include "hard-reg-set.h"
48 #include "basic-block.h"
54 #include "rtl-error.h"
57 #include "insn-attr.h"
58 #include "insn-config.h"
59 #include "cfglayout.h"
62 #include "common/common-target.h"
65 #include "tree-pass.h"
68 static int can_delete_note_p (const_rtx);
69 static int can_delete_label_p (const_rtx);
70 static basic_block rtl_split_edge (edge);
71 static bool rtl_move_block_after (basic_block, basic_block);
72 static int rtl_verify_flow_info (void);
73 static basic_block cfg_layout_split_block (basic_block, void *);
74 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
75 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
76 static void cfg_layout_delete_block (basic_block);
77 static void rtl_delete_block (basic_block);
78 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
79 static edge rtl_redirect_edge_and_branch (edge, basic_block);
80 static basic_block rtl_split_block (basic_block, void *);
81 static void rtl_dump_bb (basic_block, FILE *, int, int);
82 static int rtl_verify_flow_info_1 (void);
83 static void rtl_make_forwarder_block (edge);
85 /* Return true if NOTE is not one of the ones that must be kept paired,
86 so that we may simply delete it. */
89 can_delete_note_p (const_rtx note)
91 switch (NOTE_KIND (note))
93 case NOTE_INSN_DELETED:
94 case NOTE_INSN_BASIC_BLOCK:
95 case NOTE_INSN_EPILOGUE_BEG:
103 /* True if a given label can be deleted. */
106 can_delete_label_p (const_rtx label)
108 return (!LABEL_PRESERVE_P (label)
109 /* User declared labels must be preserved. */
110 && LABEL_NAME (label) == 0
111 && !in_expr_list_p (forced_labels, label));
114 /* Delete INSN by patching it out. Return the next insn. */
117 delete_insn (rtx insn)
119 rtx next = NEXT_INSN (insn);
121 bool really_delete = true;
125 /* Some labels can't be directly removed from the INSN chain, as they
126 might be references via variables, constant pool etc.
127 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
128 if (! can_delete_label_p (insn))
130 const char *name = LABEL_NAME (insn);
132 really_delete = false;
133 PUT_CODE (insn, NOTE);
134 NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL;
135 NOTE_DELETED_LABEL_NAME (insn) = name;
138 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
143 /* If this insn has already been deleted, something is very wrong. */
144 gcc_assert (!INSN_DELETED_P (insn));
146 INSN_DELETED_P (insn) = 1;
149 /* If deleting a jump, decrement the use count of the label. Deleting
150 the label itself should happen in the normal course of block merging. */
153 if (JUMP_LABEL (insn)
154 && LABEL_P (JUMP_LABEL (insn)))
155 LABEL_NUSES (JUMP_LABEL (insn))--;
157 /* If there are more targets, remove them too. */
159 = find_reg_note (insn, REG_LABEL_TARGET, NULL_RTX)) != NULL_RTX
160 && LABEL_P (XEXP (note, 0)))
162 LABEL_NUSES (XEXP (note, 0))--;
163 remove_note (insn, note);
167 /* Also if deleting any insn that references a label as an operand. */
168 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, NULL_RTX)) != NULL_RTX
169 && LABEL_P (XEXP (note, 0)))
171 LABEL_NUSES (XEXP (note, 0))--;
172 remove_note (insn, note);
175 if (JUMP_TABLE_DATA_P (insn))
177 rtx pat = PATTERN (insn);
178 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
179 int len = XVECLEN (pat, diff_vec_p);
182 for (i = 0; i < len; i++)
184 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
186 /* When deleting code in bulk (e.g. removing many unreachable
187 blocks) we can delete a label that's a target of the vector
188 before deleting the vector itself. */
190 LABEL_NUSES (label)--;
197 /* Like delete_insn but also purge dead edges from BB. */
200 delete_insn_and_edges (rtx insn)
206 && BLOCK_FOR_INSN (insn)
207 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
209 x = delete_insn (insn);
211 purge_dead_edges (BLOCK_FOR_INSN (insn));
215 /* Unlink a chain of insns between START and FINISH, leaving notes
216 that must be paired. If CLEAR_BB is true, we set bb field for
217 insns that cannot be removed to NULL. */
220 delete_insn_chain (rtx start, rtx finish, bool clear_bb)
224 /* Unchain the insns one by one. It would be quicker to delete all of these
225 with a single unchaining, rather than one at a time, but we need to keep
229 next = NEXT_INSN (start);
230 if (NOTE_P (start) && !can_delete_note_p (start))
233 next = delete_insn (start);
235 if (clear_bb && !INSN_DELETED_P (start))
236 set_block_for_insn (start, NULL);
244 /* Create a new basic block consisting of the instructions between HEAD and END
245 inclusive. This function is designed to allow fast BB construction - reuses
246 the note and basic block struct in BB_NOTE, if any and do not grow
247 BASIC_BLOCK chain and should be used directly only by CFG construction code.
248 END can be NULL in to create new empty basic block before HEAD. Both END
249 and HEAD can be NULL to create basic block at the end of INSN chain.
250 AFTER is the basic block we should be put after. */
253 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
258 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
261 /* If we found an existing note, thread it back onto the chain. */
269 after = PREV_INSN (head);
273 if (after != bb_note && NEXT_INSN (after) != bb_note)
274 reorder_insns_nobb (bb_note, bb_note, after);
278 /* Otherwise we must create a note and a basic block structure. */
282 init_rtl_bb_info (bb);
285 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
286 else if (LABEL_P (head) && end)
288 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
294 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
300 NOTE_BASIC_BLOCK (bb_note) = bb;
303 /* Always include the bb note in the block. */
304 if (NEXT_INSN (end) == bb_note)
309 bb->index = last_basic_block++;
310 bb->flags = BB_NEW | BB_RTL;
311 link_block (bb, after);
312 SET_BASIC_BLOCK (bb->index, bb);
313 df_bb_refs_record (bb->index, false);
314 update_bb_for_insn (bb);
315 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
317 /* Tag the block so that we know it has been used when considering
318 other basic block notes. */
324 /* Create new basic block consisting of instructions in between HEAD and END
325 and place it to the BB chain after block AFTER. END can be NULL in to
326 create new empty basic block before HEAD. Both END and HEAD can be NULL to
327 create basic block at the end of INSN chain. */
330 rtl_create_basic_block (void *headp, void *endp, basic_block after)
332 rtx head = (rtx) headp, end = (rtx) endp;
335 /* Grow the basic block array if needed. */
336 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info))
338 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
339 VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size);
344 bb = create_basic_block_structure (head, end, NULL, after);
350 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
352 basic_block newbb = rtl_create_basic_block (head, end, after);
357 /* Delete the insns in a (non-live) block. We physically delete every
358 non-deleted-note insn, and update the flow graph appropriately.
360 Return nonzero if we deleted an exception handler. */
362 /* ??? Preserving all such notes strikes me as wrong. It would be nice
363 to post-process the stream to remove empty blocks, loops, ranges, etc. */
366 rtl_delete_block (basic_block b)
370 /* If the head of this block is a CODE_LABEL, then it might be the
371 label for an exception handler which can't be reached. We need
372 to remove the label from the exception_handler_label list. */
375 end = get_last_bb_insn (b);
377 /* Selectively delete the entire chain. */
379 delete_insn_chain (insn, end, true);
383 fprintf (dump_file, "deleting block %d\n", b->index);
384 df_bb_delete (b->index);
387 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
390 compute_bb_for_insn (void)
396 rtx end = BB_END (bb);
399 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
401 BLOCK_FOR_INSN (insn) = bb;
408 /* Release the basic_block_for_insn array. */
411 free_bb_for_insn (void)
414 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
415 if (!BARRIER_P (insn))
416 BLOCK_FOR_INSN (insn) = NULL;
421 rest_of_pass_free_cfg (void)
424 /* The resource.c machinery uses DF but the CFG isn't guaranteed to be
425 valid at that point so it would be too late to call df_analyze. */
426 if (optimize > 0 && flag_delayed_branch)
428 df_note_add_problem ();
437 struct rtl_opt_pass pass_free_cfg =
441 "*free_cfg", /* name */
443 rest_of_pass_free_cfg, /* execute */
446 0, /* static_pass_number */
448 0, /* properties_required */
449 0, /* properties_provided */
450 PROP_cfg, /* properties_destroyed */
451 0, /* todo_flags_start */
452 0, /* todo_flags_finish */
456 /* Return RTX to emit after when we want to emit code on the entry of function. */
458 entry_of_function (void)
460 return (n_basic_blocks > NUM_FIXED_BLOCKS ?
461 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
464 /* Emit INSN at the entry point of the function, ensuring that it is only
465 executed once per function. */
467 emit_insn_at_entry (rtx insn)
469 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs);
470 edge e = ei_safe_edge (ei);
471 gcc_assert (e->flags & EDGE_FALLTHRU);
473 insert_insn_on_edge (insn, e);
474 commit_edge_insertions ();
477 /* Update BLOCK_FOR_INSN of insns between BEGIN and END
478 (or BARRIER if found) and notify df of the bb change.
479 The insn chain range is inclusive
480 (i.e. both BEGIN and END will be updated. */
483 update_bb_for_insn_chain (rtx begin, rtx end, basic_block bb)
487 end = NEXT_INSN (end);
488 for (insn = begin; insn != end; insn = NEXT_INSN (insn))
489 if (!BARRIER_P (insn))
490 df_insn_change_bb (insn, bb);
493 /* Update BLOCK_FOR_INSN of insns in BB to BB,
494 and notify df of the change. */
497 update_bb_for_insn (basic_block bb)
499 update_bb_for_insn_chain (BB_HEAD (bb), BB_END (bb), bb);
503 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
504 note associated with the BLOCK. */
507 first_insn_after_basic_block_note (basic_block block)
511 /* Get the first instruction in the block. */
512 insn = BB_HEAD (block);
514 if (insn == NULL_RTX)
517 insn = NEXT_INSN (insn);
518 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
520 return NEXT_INSN (insn);
523 /* Creates a new basic block just after basic block B by splitting
524 everything after specified instruction I. */
527 rtl_split_block (basic_block bb, void *insnp)
530 rtx insn = (rtx) insnp;
536 insn = first_insn_after_basic_block_note (bb);
542 insn = PREV_INSN (insn);
544 /* If the block contains only debug insns, insn would have
545 been NULL in a non-debug compilation, and then we'd end
546 up emitting a DELETED note. For -fcompare-debug
547 stability, emit the note too. */
548 if (insn != BB_END (bb)
549 && DEBUG_INSN_P (next)
550 && DEBUG_INSN_P (BB_END (bb)))
552 while (next != BB_END (bb) && DEBUG_INSN_P (next))
553 next = NEXT_INSN (next);
555 if (next == BB_END (bb))
556 emit_note_after (NOTE_INSN_DELETED, next);
560 insn = get_last_insn ();
563 /* We probably should check type of the insn so that we do not create
564 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
566 if (insn == BB_END (bb))
567 emit_note_after (NOTE_INSN_DELETED, insn);
569 /* Create the new basic block. */
570 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
571 BB_COPY_PARTITION (new_bb, bb);
574 /* Redirect the outgoing edges. */
575 new_bb->succs = bb->succs;
577 FOR_EACH_EDGE (e, ei, new_bb->succs)
580 /* The new block starts off being dirty. */
581 df_set_bb_dirty (bb);
585 /* Blocks A and B are to be merged into a single block A. The insns
586 are already contiguous. */
589 rtl_merge_blocks (basic_block a, basic_block b)
591 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
592 rtx del_first = NULL_RTX, del_last = NULL_RTX;
593 rtx b_debug_start = b_end, b_debug_end = b_end;
594 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
598 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
601 while (DEBUG_INSN_P (b_end))
602 b_end = PREV_INSN (b_debug_start = b_end);
604 /* If there was a CODE_LABEL beginning B, delete it. */
605 if (LABEL_P (b_head))
607 /* Detect basic blocks with nothing but a label. This can happen
608 in particular at the end of a function. */
612 del_first = del_last = b_head;
613 b_head = NEXT_INSN (b_head);
616 /* Delete the basic block note and handle blocks containing just that
618 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
626 b_head = NEXT_INSN (b_head);
629 /* If there was a jump out of A, delete it. */
634 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
636 || NOTE_INSN_BASIC_BLOCK_P (prev)
637 || prev == BB_HEAD (a))
643 /* If this was a conditional jump, we need to also delete
644 the insn that set cc0. */
645 if (only_sets_cc0_p (prev))
649 prev = prev_nonnote_insn (prev);
656 a_end = PREV_INSN (del_first);
658 else if (BARRIER_P (NEXT_INSN (a_end)))
659 del_first = NEXT_INSN (a_end);
661 /* Delete everything marked above as well as crap that might be
662 hanging out between the two blocks. */
664 delete_insn_chain (del_first, del_last, true);
666 /* Reassociate the insns of B with A. */
669 update_bb_for_insn_chain (a_end, b_debug_end, a);
673 else if (b_end != b_debug_end)
675 /* Move any deleted labels and other notes between the end of A
676 and the debug insns that make up B after the debug insns,
677 bringing the debug insns into A while keeping the notes after
679 if (NEXT_INSN (a_end) != b_debug_start)
680 reorder_insns_nobb (NEXT_INSN (a_end), PREV_INSN (b_debug_start),
682 update_bb_for_insn_chain (b_debug_start, b_debug_end, a);
686 df_bb_delete (b->index);
689 /* If B was a forwarder block, propagate the locus on the edge. */
690 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
691 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
694 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
698 /* Return true when block A and B can be merged. */
701 rtl_can_merge_blocks (basic_block a, basic_block b)
703 /* If we are partitioning hot/cold basic blocks, we don't want to
704 mess up unconditional or indirect jumps that cross between hot
707 Basic block partitioning may result in some jumps that appear to
708 be optimizable (or blocks that appear to be mergeable), but which really
709 must be left untouched (they are required to make it safely across
710 partition boundaries). See the comments at the top of
711 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
713 if (BB_PARTITION (a) != BB_PARTITION (b))
716 /* There must be exactly one edge in between the blocks. */
717 return (single_succ_p (a)
718 && single_succ (a) == b
721 /* Must be simple edge. */
722 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
724 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
725 /* If the jump insn has side effects,
726 we can't kill the edge. */
727 && (!JUMP_P (BB_END (a))
729 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
732 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
736 block_label (basic_block block)
738 if (block == EXIT_BLOCK_PTR)
741 if (!LABEL_P (BB_HEAD (block)))
743 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
746 return BB_HEAD (block);
749 /* Attempt to perform edge redirection by replacing possibly complex jump
750 instruction by unconditional jump or removing jump completely. This can
751 apply only if all edges now point to the same block. The parameters and
752 return values are equivalent to redirect_edge_and_branch. */
755 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
757 basic_block src = e->src;
758 rtx insn = BB_END (src), kill_from;
762 /* If we are partitioning hot/cold basic blocks, we don't want to
763 mess up unconditional or indirect jumps that cross between hot
766 Basic block partitioning may result in some jumps that appear to
767 be optimizable (or blocks that appear to be mergeable), but which really
768 must be left untouched (they are required to make it safely across
769 partition boundaries). See the comments at the top of
770 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
772 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
773 || BB_PARTITION (src) != BB_PARTITION (target))
776 /* We can replace or remove a complex jump only when we have exactly
777 two edges. Also, if we have exactly one outgoing edge, we can
779 if (EDGE_COUNT (src->succs) >= 3
780 /* Verify that all targets will be TARGET. Specifically, the
781 edge that is not E must also go to TARGET. */
782 || (EDGE_COUNT (src->succs) == 2
783 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
786 if (!onlyjump_p (insn))
788 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
791 /* Avoid removing branch with side effects. */
792 set = single_set (insn);
793 if (!set || side_effects_p (set))
796 /* In case we zap a conditional jump, we'll need to kill
797 the cc0 setter too. */
800 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
801 && only_sets_cc0_p (PREV_INSN (insn)))
802 kill_from = PREV_INSN (insn);
805 /* See if we can create the fallthru edge. */
806 if (in_cfglayout || can_fallthru (src, target))
809 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
812 /* Selectively unlink whole insn chain. */
815 rtx insn = src->il.rtl->footer;
817 delete_insn_chain (kill_from, BB_END (src), false);
819 /* Remove barriers but keep jumptables. */
822 if (BARRIER_P (insn))
824 if (PREV_INSN (insn))
825 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
827 src->il.rtl->footer = NEXT_INSN (insn);
828 if (NEXT_INSN (insn))
829 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
833 insn = NEXT_INSN (insn);
837 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
841 /* If this already is simplejump, redirect it. */
842 else if (simplejump_p (insn))
844 if (e->dest == target)
847 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
848 INSN_UID (insn), e->dest->index, target->index);
849 if (!redirect_jump (insn, block_label (target), 0))
851 gcc_assert (target == EXIT_BLOCK_PTR);
856 /* Cannot do anything for target exit block. */
857 else if (target == EXIT_BLOCK_PTR)
860 /* Or replace possibly complicated jump insn by simple jump insn. */
863 rtx target_label = block_label (target);
864 rtx barrier, label, table;
866 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
867 JUMP_LABEL (BB_END (src)) = target_label;
868 LABEL_NUSES (target_label)++;
870 fprintf (dump_file, "Replacing insn %i by jump %i\n",
871 INSN_UID (insn), INSN_UID (BB_END (src)));
874 delete_insn_chain (kill_from, insn, false);
876 /* Recognize a tablejump that we are converting to a
877 simple jump and remove its associated CODE_LABEL
878 and ADDR_VEC or ADDR_DIFF_VEC. */
879 if (tablejump_p (insn, &label, &table))
880 delete_insn_chain (label, table, false);
882 barrier = next_nonnote_insn (BB_END (src));
883 if (!barrier || !BARRIER_P (barrier))
884 emit_barrier_after (BB_END (src));
887 if (barrier != NEXT_INSN (BB_END (src)))
889 /* Move the jump before barrier so that the notes
890 which originally were or were created before jump table are
891 inside the basic block. */
892 rtx new_insn = BB_END (src);
894 update_bb_for_insn_chain (NEXT_INSN (BB_END (src)),
895 PREV_INSN (barrier), src);
897 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
898 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
900 NEXT_INSN (new_insn) = barrier;
901 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
903 PREV_INSN (new_insn) = PREV_INSN (barrier);
904 PREV_INSN (barrier) = new_insn;
909 /* Keep only one edge out and set proper flags. */
910 if (!single_succ_p (src))
912 gcc_assert (single_succ_p (src));
914 e = single_succ_edge (src);
916 e->flags = EDGE_FALLTHRU;
920 e->probability = REG_BR_PROB_BASE;
921 e->count = src->count;
923 if (e->dest != target)
924 redirect_edge_succ (e, target);
928 /* Subroutine of redirect_branch_edge that tries to patch the jump
929 instruction INSN so that it reaches block NEW. Do this
930 only when it originally reached block OLD. Return true if this
931 worked or the original target wasn't OLD, return false if redirection
935 patch_jump_insn (rtx insn, rtx old_label, basic_block new_bb)
938 /* Recognize a tablejump and adjust all matching cases. */
939 if (tablejump_p (insn, NULL, &tmp))
943 rtx new_label = block_label (new_bb);
945 if (new_bb == EXIT_BLOCK_PTR)
947 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
948 vec = XVEC (PATTERN (tmp), 0);
950 vec = XVEC (PATTERN (tmp), 1);
952 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
953 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
955 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
956 --LABEL_NUSES (old_label);
957 ++LABEL_NUSES (new_label);
960 /* Handle casesi dispatch insns. */
961 if ((tmp = single_set (insn)) != NULL
962 && SET_DEST (tmp) == pc_rtx
963 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
964 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
965 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
967 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
969 --LABEL_NUSES (old_label);
970 ++LABEL_NUSES (new_label);
973 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
975 int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp);
978 if (new_bb == EXIT_BLOCK_PTR)
980 new_label = block_label (new_bb);
982 for (i = 0; i < n; ++i)
984 rtx old_ref = ASM_OPERANDS_LABEL (tmp, i);
985 gcc_assert (GET_CODE (old_ref) == LABEL_REF);
986 if (XEXP (old_ref, 0) == old_label)
988 ASM_OPERANDS_LABEL (tmp, i)
989 = gen_rtx_LABEL_REF (Pmode, new_label);
990 --LABEL_NUSES (old_label);
991 ++LABEL_NUSES (new_label);
995 if (JUMP_LABEL (insn) == old_label)
997 JUMP_LABEL (insn) = new_label;
998 note = find_reg_note (insn, REG_LABEL_TARGET, new_label);
1000 remove_note (insn, note);
1004 note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
1006 remove_note (insn, note);
1007 if (JUMP_LABEL (insn) != new_label
1008 && !find_reg_note (insn, REG_LABEL_TARGET, new_label))
1009 add_reg_note (insn, REG_LABEL_TARGET, new_label);
1011 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label))
1013 XEXP (note, 0) = new_label;
1017 /* ?? We may play the games with moving the named labels from
1018 one basic block to the other in case only one computed_jump is
1020 if (computed_jump_p (insn)
1021 /* A return instruction can't be redirected. */
1022 || returnjump_p (insn))
1025 if (!currently_expanding_to_rtl || JUMP_LABEL (insn) == old_label)
1027 /* If the insn doesn't go where we think, we're confused. */
1028 gcc_assert (JUMP_LABEL (insn) == old_label);
1030 /* If the substitution doesn't succeed, die. This can happen
1031 if the back end emitted unrecognizable instructions or if
1032 target is exit block on some arches. */
1033 if (!redirect_jump (insn, block_label (new_bb), 0))
1035 gcc_assert (new_bb == EXIT_BLOCK_PTR);
1044 /* Redirect edge representing branch of (un)conditional jump or tablejump,
1047 redirect_branch_edge (edge e, basic_block target)
1049 rtx old_label = BB_HEAD (e->dest);
1050 basic_block src = e->src;
1051 rtx insn = BB_END (src);
1053 /* We can only redirect non-fallthru edges of jump insn. */
1054 if (e->flags & EDGE_FALLTHRU)
1056 else if (!JUMP_P (insn) && !currently_expanding_to_rtl)
1059 if (!currently_expanding_to_rtl)
1061 if (!patch_jump_insn (insn, old_label, target))
1065 /* When expanding this BB might actually contain multiple
1066 jumps (i.e. not yet split by find_many_sub_basic_blocks).
1067 Redirect all of those that match our label. */
1068 FOR_BB_INSNS (src, insn)
1069 if (JUMP_P (insn) && !patch_jump_insn (insn, old_label, target))
1073 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
1074 e->src->index, e->dest->index, target->index);
1076 if (e->dest != target)
1077 e = redirect_edge_succ_nodup (e, target);
1082 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
1083 expense of adding new instructions or reordering basic blocks.
1085 Function can be also called with edge destination equivalent to the TARGET.
1086 Then it should try the simplifications and do nothing if none is possible.
1088 Return edge representing the branch if transformation succeeded. Return NULL
1090 We still return NULL in case E already destinated TARGET and we didn't
1091 managed to simplify instruction stream. */
1094 rtl_redirect_edge_and_branch (edge e, basic_block target)
1097 basic_block src = e->src;
1099 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
1102 if (e->dest == target)
1105 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
1107 df_set_bb_dirty (src);
1111 ret = redirect_branch_edge (e, target);
1115 df_set_bb_dirty (src);
1119 /* Like force_nonfallthru below, but additionally performs redirection
1120 Used by redirect_edge_and_branch_force. */
1123 force_nonfallthru_and_redirect (edge e, basic_block target)
1125 basic_block jump_block, new_bb = NULL, src = e->src;
1128 int abnormal_edge_flags = 0;
1131 /* In the case the last instruction is conditional jump to the next
1132 instruction, first redirect the jump itself and then continue
1133 by creating a basic block afterwards to redirect fallthru edge. */
1134 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1135 && any_condjump_p (BB_END (e->src))
1136 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1139 edge b = unchecked_make_edge (e->src, target, 0);
1142 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1143 gcc_assert (redirected);
1145 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1148 int prob = INTVAL (XEXP (note, 0));
1150 b->probability = prob;
1151 b->count = e->count * prob / REG_BR_PROB_BASE;
1152 e->probability -= e->probability;
1153 e->count -= b->count;
1154 if (e->probability < 0)
1161 if (e->flags & EDGE_ABNORMAL)
1163 /* Irritating special case - fallthru edge to the same block as abnormal
1165 We can't redirect abnormal edge, but we still can split the fallthru
1166 one and create separate abnormal edge to original destination.
1167 This allows bb-reorder to make such edge non-fallthru. */
1168 gcc_assert (e->dest == target);
1169 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1170 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1174 gcc_assert (e->flags & EDGE_FALLTHRU);
1175 if (e->src == ENTRY_BLOCK_PTR)
1177 /* We can't redirect the entry block. Create an empty block
1178 at the start of the function which we use to add the new
1184 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1186 /* Change the existing edge's source to be the new block, and add
1187 a new edge from the entry block to the new block. */
1189 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1193 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1203 VEC_safe_push (edge, gc, bb->succs, e);
1204 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1208 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1210 /* Create the new structures. */
1212 /* If the old block ended with a tablejump, skip its table
1213 by searching forward from there. Otherwise start searching
1214 forward from the last instruction of the old block. */
1215 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1216 note = BB_END (e->src);
1217 note = NEXT_INSN (note);
1219 jump_block = create_basic_block (note, NULL, e->src);
1220 jump_block->count = e->count;
1221 jump_block->frequency = EDGE_FREQUENCY (e);
1222 jump_block->loop_depth = target->loop_depth;
1224 /* Make sure new block ends up in correct hot/cold section. */
1226 BB_COPY_PARTITION (jump_block, e->src);
1227 if (flag_reorder_blocks_and_partition
1228 && targetm_common.have_named_sections
1229 && JUMP_P (BB_END (jump_block))
1230 && !any_condjump_p (BB_END (jump_block))
1231 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1232 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX);
1235 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1236 new_edge->probability = e->probability;
1237 new_edge->count = e->count;
1239 /* Redirect old edge. */
1240 redirect_edge_pred (e, jump_block);
1241 e->probability = REG_BR_PROB_BASE;
1243 new_bb = jump_block;
1246 jump_block = e->src;
1248 if (e->goto_locus && e->goto_block == NULL)
1249 loc = e->goto_locus;
1252 e->flags &= ~EDGE_FALLTHRU;
1253 if (target == EXIT_BLOCK_PTR)
1256 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc);
1263 rtx label = block_label (target);
1264 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc);
1265 JUMP_LABEL (BB_END (jump_block)) = label;
1266 LABEL_NUSES (label)++;
1269 emit_barrier_after (BB_END (jump_block));
1270 redirect_edge_succ_nodup (e, target);
1272 if (abnormal_edge_flags)
1273 make_edge (src, target, abnormal_edge_flags);
1275 df_mark_solutions_dirty ();
1279 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1280 (and possibly create new basic block) to make edge non-fallthru.
1281 Return newly created BB or NULL if none. */
1284 rtl_force_nonfallthru (edge e)
1286 return force_nonfallthru_and_redirect (e, e->dest);
1289 /* Redirect edge even at the expense of creating new jump insn or
1290 basic block. Return new basic block if created, NULL otherwise.
1291 Conversion must be possible. */
1294 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1296 if (redirect_edge_and_branch (e, target)
1297 || e->dest == target)
1300 /* In case the edge redirection failed, try to force it to be non-fallthru
1301 and redirect newly created simplejump. */
1302 df_set_bb_dirty (e->src);
1303 return force_nonfallthru_and_redirect (e, target);
1306 /* The given edge should potentially be a fallthru edge. If that is in
1307 fact true, delete the jump and barriers that are in the way. */
1310 rtl_tidy_fallthru_edge (edge e)
1313 basic_block b = e->src, c = b->next_bb;
1315 /* ??? In a late-running flow pass, other folks may have deleted basic
1316 blocks by nopping out blocks, leaving multiple BARRIERs between here
1317 and the target label. They ought to be chastised and fixed.
1319 We can also wind up with a sequence of undeletable labels between
1320 one block and the next.
1322 So search through a sequence of barriers, labels, and notes for
1323 the head of block C and assert that we really do fall through. */
1325 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1329 /* Remove what will soon cease being the jump insn from the source block.
1330 If block B consisted only of this single jump, turn it into a deleted
1335 && (any_uncondjump_p (q)
1336 || single_succ_p (b)))
1339 /* If this was a conditional jump, we need to also delete
1340 the insn that set cc0. */
1341 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1348 /* Selectively unlink the sequence. */
1349 if (q != PREV_INSN (BB_HEAD (c)))
1350 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false);
1352 e->flags |= EDGE_FALLTHRU;
1355 /* Should move basic block BB after basic block AFTER. NIY. */
1358 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1359 basic_block after ATTRIBUTE_UNUSED)
1364 /* Split a (typically critical) edge. Return the new block.
1365 The edge must not be abnormal.
1367 ??? The code generally expects to be called on critical edges.
1368 The case of a block ending in an unconditional jump to a
1369 block with multiple predecessors is not handled optimally. */
1372 rtl_split_edge (edge edge_in)
1377 /* Abnormal edges cannot be split. */
1378 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1380 /* We are going to place the new block in front of edge destination.
1381 Avoid existence of fallthru predecessors. */
1382 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1384 edge e = find_fallthru_edge (edge_in->dest->preds);
1387 force_nonfallthru (e);
1390 /* Create the basic block note. */
1391 if (edge_in->dest != EXIT_BLOCK_PTR)
1392 before = BB_HEAD (edge_in->dest);
1396 /* If this is a fall through edge to the exit block, the blocks might be
1397 not adjacent, and the right place is the after the source. */
1398 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1400 before = NEXT_INSN (BB_END (edge_in->src));
1401 bb = create_basic_block (before, NULL, edge_in->src);
1402 BB_COPY_PARTITION (bb, edge_in->src);
1406 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1407 /* ??? Why not edge_in->dest->prev_bb here? */
1408 BB_COPY_PARTITION (bb, edge_in->dest);
1411 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1413 /* For non-fallthru edges, we must adjust the predecessor's
1414 jump instruction to target our new block. */
1415 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1417 edge redirected = redirect_edge_and_branch (edge_in, bb);
1418 gcc_assert (redirected);
1422 if (edge_in->src != ENTRY_BLOCK_PTR)
1424 /* For asm goto even splitting of fallthru edge might
1425 need insn patching, as other labels might point to the
1427 rtx last = BB_END (edge_in->src);
1430 && edge_in->dest != EXIT_BLOCK_PTR
1431 && extract_asm_operands (PATTERN (last)) != NULL_RTX
1432 && patch_jump_insn (last, before, bb))
1433 df_set_bb_dirty (edge_in->src);
1435 redirect_edge_succ (edge_in, bb);
1441 /* Queue instructions for insertion on an edge between two basic blocks.
1442 The new instructions and basic blocks (if any) will not appear in the
1443 CFG until commit_edge_insertions is called. */
1446 insert_insn_on_edge (rtx pattern, edge e)
1448 /* We cannot insert instructions on an abnormal critical edge.
1449 It will be easier to find the culprit if we die now. */
1450 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1452 if (e->insns.r == NULL_RTX)
1455 push_to_sequence (e->insns.r);
1457 emit_insn (pattern);
1459 e->insns.r = get_insns ();
1463 /* Update the CFG for the instructions queued on edge E. */
1466 commit_one_edge_insertion (edge e)
1468 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1471 /* Pull the insns off the edge now since the edge might go away. */
1473 e->insns.r = NULL_RTX;
1475 /* Figure out where to put these insns. If the destination has
1476 one predecessor, insert there. Except for the exit block. */
1477 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1481 /* Get the location correct wrt a code label, and "nice" wrt
1482 a basic block note, and before everything else. */
1485 tmp = NEXT_INSN (tmp);
1486 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1487 tmp = NEXT_INSN (tmp);
1488 if (tmp == BB_HEAD (bb))
1491 after = PREV_INSN (tmp);
1493 after = get_last_insn ();
1496 /* If the source has one successor and the edge is not abnormal,
1497 insert there. Except for the entry block. */
1498 else if ((e->flags & EDGE_ABNORMAL) == 0
1499 && single_succ_p (e->src)
1500 && e->src != ENTRY_BLOCK_PTR)
1504 /* It is possible to have a non-simple jump here. Consider a target
1505 where some forms of unconditional jumps clobber a register. This
1506 happens on the fr30 for example.
1508 We know this block has a single successor, so we can just emit
1509 the queued insns before the jump. */
1510 if (JUMP_P (BB_END (bb)))
1511 before = BB_END (bb);
1514 /* We'd better be fallthru, or we've lost track of what's what. */
1515 gcc_assert (e->flags & EDGE_FALLTHRU);
1517 after = BB_END (bb);
1521 /* Otherwise we must split the edge. */
1524 bb = split_edge (e);
1525 after = BB_END (bb);
1527 if (flag_reorder_blocks_and_partition
1528 && targetm_common.have_named_sections
1529 && e->src != ENTRY_BLOCK_PTR
1530 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1531 && !(e->flags & EDGE_CROSSING)
1533 && !any_condjump_p (after)
1534 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1535 add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX);
1538 /* Now that we've found the spot, do the insertion. */
1541 emit_insn_before_noloc (insns, before, bb);
1542 last = prev_nonnote_insn (before);
1545 last = emit_insn_after_noloc (insns, after, bb);
1547 if (returnjump_p (last))
1549 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1550 This is not currently a problem because this only happens
1551 for the (single) epilogue, which already has a fallthru edge
1554 e = single_succ_edge (bb);
1555 gcc_assert (e->dest == EXIT_BLOCK_PTR
1556 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1558 e->flags &= ~EDGE_FALLTHRU;
1559 emit_barrier_after (last);
1562 delete_insn (before);
1565 gcc_assert (!JUMP_P (last));
1568 /* Update the CFG for all queued instructions. */
1571 commit_edge_insertions (void)
1575 #ifdef ENABLE_CHECKING
1576 verify_flow_info ();
1579 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1584 FOR_EACH_EDGE (e, ei, bb->succs)
1586 commit_one_edge_insertion (e);
1591 /* Print out RTL-specific basic block information (live information
1592 at start and end). */
1595 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED)
1601 s_indent = (char *) alloca ((size_t) indent + 1);
1602 memset (s_indent, ' ', (size_t) indent);
1603 s_indent[indent] = '\0';
1607 df_dump_top (bb, outf);
1611 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1612 insn = NEXT_INSN (insn))
1613 print_rtl_single (outf, insn);
1617 df_dump_bottom (bb, outf);
1623 /* Like print_rtl, but also print out live information for the start of each
1627 print_rtl_with_bb (FILE *outf, const_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);
1643 df_dump_start (outf);
1645 FOR_EACH_BB_REVERSE (bb)
1649 start[INSN_UID (BB_HEAD (bb))] = bb;
1650 end[INSN_UID (BB_END (bb))] = bb;
1651 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1653 enum bb_state state = IN_MULTIPLE_BB;
1655 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1657 in_bb_p[INSN_UID (x)] = state;
1659 if (x == BB_END (bb))
1664 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1668 bb = start[INSN_UID (tmp_rtx)];
1670 dump_bb_info (bb, true, false, dump_flags, ";; ", outf);
1672 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1673 && !NOTE_P (tmp_rtx)
1674 && !BARRIER_P (tmp_rtx))
1675 fprintf (outf, ";; Insn is not within a basic block\n");
1676 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1677 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1679 did_output = print_rtl_single (outf, tmp_rtx);
1681 bb = end[INSN_UID (tmp_rtx)];
1683 dump_bb_info (bb, false, true, dump_flags, ";; ", outf);
1693 if (crtl->epilogue_delay_list != 0)
1695 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1696 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0;
1697 tmp_rtx = XEXP (tmp_rtx, 1))
1698 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1703 update_br_prob_note (basic_block bb)
1706 if (!JUMP_P (BB_END (bb)))
1708 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1709 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1711 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1714 /* Get the last insn associated with block BB (that includes barriers and
1715 tablejumps after BB). */
1717 get_last_bb_insn (basic_block bb)
1720 rtx end = BB_END (bb);
1722 /* Include any jump table following the basic block. */
1723 if (tablejump_p (end, NULL, &tmp))
1726 /* Include any barriers that may follow the basic block. */
1727 tmp = next_nonnote_insn_bb (end);
1728 while (tmp && BARRIER_P (tmp))
1731 tmp = next_nonnote_insn_bb (end);
1737 /* Verify the CFG and RTL consistency common for both underlying RTL and
1740 Currently it does following checks:
1742 - overlapping of basic blocks
1743 - insns with wrong BLOCK_FOR_INSN pointers
1744 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1745 - tails of basic blocks (ensure that boundary is necessary)
1746 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1747 and NOTE_INSN_BASIC_BLOCK
1748 - verify that no fall_thru edge crosses hot/cold partition boundaries
1749 - verify that there are no pending RTL branch predictions
1751 In future it can be extended check a lot of other stuff as well
1752 (reachability of basic blocks, life information, etc. etc.). */
1755 rtl_verify_flow_info_1 (void)
1761 /* Check the general integrity of the basic blocks. */
1762 FOR_EACH_BB_REVERSE (bb)
1766 if (!(bb->flags & BB_RTL))
1768 error ("BB_RTL flag not set for block %d", bb->index);
1772 FOR_BB_INSNS (bb, insn)
1773 if (BLOCK_FOR_INSN (insn) != bb)
1775 error ("insn %d basic block pointer is %d, should be %d",
1777 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1782 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1783 if (!BARRIER_P (insn)
1784 && BLOCK_FOR_INSN (insn) != NULL)
1786 error ("insn %d in header of bb %d has non-NULL basic block",
1787 INSN_UID (insn), bb->index);
1790 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1791 if (!BARRIER_P (insn)
1792 && BLOCK_FOR_INSN (insn) != NULL)
1794 error ("insn %d in footer of bb %d has non-NULL basic block",
1795 INSN_UID (insn), 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 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1855 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1860 error ("too many eh edges %i", bb->index);
1864 && (!JUMP_P (BB_END (bb))
1865 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1866 || any_condjump_p (BB_END (bb))))))
1868 error ("too many outgoing branch edges from bb %i", bb->index);
1871 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1873 error ("fallthru edge after unconditional jump %i", bb->index);
1876 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1878 error ("wrong number of branch edges after unconditional jump %i",
1882 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1883 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1885 error ("wrong amount of branch edges after conditional jump %i",
1889 if (n_call && !CALL_P (BB_END (bb)))
1891 error ("call edges for non-call insn in bb %i", bb->index);
1895 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1896 && (!JUMP_P (BB_END (bb))
1897 || any_condjump_p (BB_END (bb))
1898 || any_uncondjump_p (BB_END (bb))))
1900 error ("abnormal edges for no purpose in bb %i", bb->index);
1904 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1905 /* We may have a barrier inside a basic block before dead code
1906 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1907 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1910 if (! BLOCK_FOR_INSN (x))
1912 ("insn %d inside basic block %d but block_for_insn is NULL",
1913 INSN_UID (x), bb->index);
1916 ("insn %d inside basic block %d but block_for_insn is %i",
1917 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1922 /* OK pointers are correct. Now check the header of basic
1923 block. It ought to contain optional CODE_LABEL followed
1924 by NOTE_BASIC_BLOCK. */
1928 if (BB_END (bb) == x)
1930 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1938 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1940 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1945 if (BB_END (bb) == x)
1946 /* Do checks for empty blocks here. */
1949 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1951 if (NOTE_INSN_BASIC_BLOCK_P (x))
1953 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1954 INSN_UID (x), bb->index);
1958 if (x == BB_END (bb))
1961 if (control_flow_insn_p (x))
1963 error ("in basic block %d:", bb->index);
1964 fatal_insn ("flow control insn inside a basic block", x);
1973 /* Verify the CFG and RTL consistency common for both underlying RTL and
1976 Currently it does following checks:
1977 - all checks of rtl_verify_flow_info_1
1978 - test head/end pointers
1979 - check that all insns are in the basic blocks
1980 (except the switch handling code, barriers and notes)
1981 - check that all returns are followed by barriers
1982 - check that all fallthru edge points to the adjacent blocks. */
1985 rtl_verify_flow_info (void)
1988 int err = rtl_verify_flow_info_1 ();
1990 rtx last_head = get_last_insn ();
1991 basic_block *bb_info;
1993 const rtx rtx_first = get_insns ();
1994 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
1995 const int max_uid = get_max_uid ();
1997 bb_info = XCNEWVEC (basic_block, max_uid);
1999 FOR_EACH_BB_REVERSE (bb)
2002 rtx head = BB_HEAD (bb);
2003 rtx end = BB_END (bb);
2005 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2007 /* Verify the end of the basic block is in the INSN chain. */
2011 /* And that the code outside of basic blocks has NULL bb field. */
2013 && BLOCK_FOR_INSN (x) != NULL)
2015 error ("insn %d outside of basic blocks has non-NULL bb field",
2023 error ("end insn %d for block %d not found in the insn stream",
2024 INSN_UID (end), bb->index);
2028 /* Work backwards from the end to the head of the basic block
2029 to verify the head is in the RTL chain. */
2030 for (; x != NULL_RTX; x = PREV_INSN (x))
2032 /* While walking over the insn chain, verify insns appear
2033 in only one basic block. */
2034 if (bb_info[INSN_UID (x)] != NULL)
2036 error ("insn %d is in multiple basic blocks (%d and %d)",
2037 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
2041 bb_info[INSN_UID (x)] = bb;
2048 error ("head insn %d for block %d not found in the insn stream",
2049 INSN_UID (head), bb->index);
2053 last_head = PREV_INSN (x);
2055 e = find_fallthru_edge (bb->succs);
2060 /* Ensure existence of barrier in BB with no fallthru edges. */
2061 for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn))
2063 if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn))
2065 error ("missing barrier after block %i", bb->index);
2069 if (BARRIER_P (insn))
2073 else if (e->src != ENTRY_BLOCK_PTR
2074 && e->dest != EXIT_BLOCK_PTR)
2078 if (e->src->next_bb != e->dest)
2081 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2082 e->src->index, e->dest->index);
2086 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2087 insn = NEXT_INSN (insn))
2088 if (BARRIER_P (insn) || INSN_P (insn))
2090 error ("verify_flow_info: Incorrect fallthru %i->%i",
2091 e->src->index, e->dest->index);
2092 fatal_insn ("wrong insn in the fallthru edge", insn);
2098 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2100 /* Check that the code before the first basic block has NULL
2103 && BLOCK_FOR_INSN (x) != NULL)
2105 error ("insn %d outside of basic blocks has non-NULL bb field",
2113 last_bb_seen = ENTRY_BLOCK_PTR;
2115 for (x = rtx_first; x; x = NEXT_INSN (x))
2117 if (NOTE_INSN_BASIC_BLOCK_P (x))
2119 bb = NOTE_BASIC_BLOCK (x);
2122 if (bb != last_bb_seen->next_bb)
2123 internal_error ("basic blocks not laid down consecutively");
2125 curr_bb = last_bb_seen = bb;
2130 switch (GET_CODE (x))
2137 /* An addr_vec is placed outside any basic block. */
2139 && JUMP_TABLE_DATA_P (NEXT_INSN (x)))
2142 /* But in any case, non-deletable labels can appear anywhere. */
2146 fatal_insn ("insn outside basic block", x);
2151 && returnjump_p (x) && ! condjump_p (x)
2152 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2153 fatal_insn ("return not followed by barrier", x);
2154 if (curr_bb && x == BB_END (curr_bb))
2158 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2160 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2161 num_bb_notes, n_basic_blocks);
2166 /* Assume that the preceding pass has possibly eliminated jump instructions
2167 or converted the unconditional jumps. Eliminate the edges from CFG.
2168 Return true if any edges are eliminated. */
2171 purge_dead_edges (basic_block bb)
2174 rtx insn = BB_END (bb), note;
2175 bool purged = false;
2179 if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb))
2181 insn = PREV_INSN (insn);
2182 while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb));
2184 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2185 if (NONJUMP_INSN_P (insn)
2186 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2190 if (! may_trap_p (PATTERN (insn))
2191 || ((eqnote = find_reg_equal_equiv_note (insn))
2192 && ! may_trap_p (XEXP (eqnote, 0))))
2193 remove_note (insn, note);
2196 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2197 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2199 bool remove = false;
2201 /* There are three types of edges we need to handle correctly here: EH
2202 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2203 latter can appear when nonlocal gotos are used. */
2204 if (e->flags & EDGE_ABNORMAL_CALL)
2208 else if (can_nonlocal_goto (insn))
2210 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2215 else if (e->flags & EDGE_EH)
2216 remove = !can_throw_internal (insn);
2221 df_set_bb_dirty (bb);
2234 /* We do care only about conditional jumps and simplejumps. */
2235 if (!any_condjump_p (insn)
2236 && !returnjump_p (insn)
2237 && !simplejump_p (insn))
2240 /* Branch probability/prediction notes are defined only for
2241 condjumps. We've possibly turned condjump into simplejump. */
2242 if (simplejump_p (insn))
2244 note = find_reg_note (insn, REG_BR_PROB, NULL);
2246 remove_note (insn, note);
2247 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2248 remove_note (insn, note);
2251 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2253 /* Avoid abnormal flags to leak from computed jumps turned
2254 into simplejumps. */
2256 e->flags &= ~EDGE_ABNORMAL;
2258 /* See if this edge is one we should keep. */
2259 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2260 /* A conditional jump can fall through into the next
2261 block, so we should keep the edge. */
2266 else if (e->dest != EXIT_BLOCK_PTR
2267 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2268 /* If the destination block is the target of the jump,
2274 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2275 /* If the destination block is the exit block, and this
2276 instruction is a return, then keep the edge. */
2281 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2282 /* Keep the edges that correspond to exceptions thrown by
2283 this instruction and rematerialize the EDGE_ABNORMAL
2284 flag we just cleared above. */
2286 e->flags |= EDGE_ABNORMAL;
2291 /* We do not need this edge. */
2292 df_set_bb_dirty (bb);
2297 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2301 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2306 /* Redistribute probabilities. */
2307 if (single_succ_p (bb))
2309 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2310 single_succ_edge (bb)->count = bb->count;
2314 note = find_reg_note (insn, REG_BR_PROB, NULL);
2318 b = BRANCH_EDGE (bb);
2319 f = FALLTHRU_EDGE (bb);
2320 b->probability = INTVAL (XEXP (note, 0));
2321 f->probability = REG_BR_PROB_BASE - b->probability;
2322 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2323 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2328 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2330 /* First, there should not be any EH or ABCALL edges resulting
2331 from non-local gotos and the like. If there were, we shouldn't
2332 have created the sibcall in the first place. Second, there
2333 should of course never have been a fallthru edge. */
2334 gcc_assert (single_succ_p (bb));
2335 gcc_assert (single_succ_edge (bb)->flags
2336 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2341 /* If we don't see a jump insn, we don't know exactly why the block would
2342 have been broken at this point. Look for a simple, non-fallthru edge,
2343 as these are only created by conditional branches. If we find such an
2344 edge we know that there used to be a jump here and can then safely
2345 remove all non-fallthru edges. */
2347 FOR_EACH_EDGE (e, ei, bb->succs)
2348 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2357 /* Remove all but the fake and fallthru edges. The fake edge may be
2358 the only successor for this block in the case of noreturn
2360 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2362 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2364 df_set_bb_dirty (bb);
2372 gcc_assert (single_succ_p (bb));
2374 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2375 single_succ_edge (bb)->count = bb->count;
2378 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2383 /* Search all basic blocks for potentially dead edges and purge them. Return
2384 true if some edge has been eliminated. */
2387 purge_all_dead_edges (void)
2394 bool purged_here = purge_dead_edges (bb);
2396 purged |= purged_here;
2402 /* This is used by a few passes that emit some instructions after abnormal
2403 calls, moving the basic block's end, while they in fact do want to emit
2404 them on the fallthru edge. Look for abnormal call edges, find backward
2405 the call in the block and insert the instructions on the edge instead.
2407 Similarly, handle instructions throwing exceptions internally.
2409 Return true when instructions have been found and inserted on edges. */
2412 fixup_abnormal_edges (void)
2414 bool inserted = false;
2422 /* Look for cases we are interested in - calls or instructions causing
2424 FOR_EACH_EDGE (e, ei, bb->succs)
2425 if ((e->flags & EDGE_ABNORMAL_CALL)
2426 || ((e->flags & (EDGE_ABNORMAL | EDGE_EH))
2427 == (EDGE_ABNORMAL | EDGE_EH)))
2430 if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb)))
2434 /* Get past the new insns generated. Allow notes, as the insns
2435 may be already deleted. */
2437 while ((NONJUMP_INSN_P (insn) || NOTE_P (insn))
2438 && !can_throw_internal (insn)
2439 && insn != BB_HEAD (bb))
2440 insn = PREV_INSN (insn);
2442 if (CALL_P (insn) || can_throw_internal (insn))
2446 e = find_fallthru_edge (bb->succs);
2448 stop = NEXT_INSN (BB_END (bb));
2451 for (insn = NEXT_INSN (insn); insn != stop; insn = next)
2453 next = NEXT_INSN (insn);
2458 /* Sometimes there's still the return value USE.
2459 If it's placed after a trapping call (i.e. that
2460 call is the last insn anyway), we have no fallthru
2461 edge. Simply delete this use and don't try to insert
2462 on the non-existent edge. */
2463 if (GET_CODE (PATTERN (insn)) != USE)
2465 /* We're not deleting it, we're moving it. */
2466 INSN_DELETED_P (insn) = 0;
2467 PREV_INSN (insn) = NULL_RTX;
2468 NEXT_INSN (insn) = NULL_RTX;
2470 insert_insn_on_edge (insn, e);
2474 else if (!BARRIER_P (insn))
2475 set_block_for_insn (insn, NULL);
2479 /* It may be that we don't find any trapping insn. In this
2480 case we discovered quite late that the insn that had been
2481 marked as can_throw_internal in fact couldn't trap at all.
2482 So we should in fact delete the EH edges out of the block. */
2484 purge_dead_edges (bb);
2491 /* Same as split_block but update cfg_layout structures. */
2494 cfg_layout_split_block (basic_block bb, void *insnp)
2496 rtx insn = (rtx) insnp;
2497 basic_block new_bb = rtl_split_block (bb, insn);
2499 new_bb->il.rtl->footer = bb->il.rtl->footer;
2500 bb->il.rtl->footer = NULL;
2505 /* Redirect Edge to DEST. */
2507 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2509 basic_block src = e->src;
2512 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2515 if (e->dest == dest)
2518 if (e->src != ENTRY_BLOCK_PTR
2519 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2521 df_set_bb_dirty (src);
2525 if (e->src == ENTRY_BLOCK_PTR
2526 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2529 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2530 e->src->index, dest->index);
2532 df_set_bb_dirty (e->src);
2533 redirect_edge_succ (e, dest);
2537 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2538 in the case the basic block appears to be in sequence. Avoid this
2541 if (e->flags & EDGE_FALLTHRU)
2543 /* Redirect any branch edges unified with the fallthru one. */
2544 if (JUMP_P (BB_END (src))
2545 && label_is_jump_target_p (BB_HEAD (e->dest),
2551 fprintf (dump_file, "Fallthru edge unified with branch "
2552 "%i->%i redirected to %i\n",
2553 e->src->index, e->dest->index, dest->index);
2554 e->flags &= ~EDGE_FALLTHRU;
2555 redirected = redirect_branch_edge (e, dest);
2556 gcc_assert (redirected);
2557 redirected->flags |= EDGE_FALLTHRU;
2558 df_set_bb_dirty (redirected->src);
2561 /* In case we are redirecting fallthru edge to the branch edge
2562 of conditional jump, remove it. */
2563 if (EDGE_COUNT (src->succs) == 2)
2565 /* Find the edge that is different from E. */
2566 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2569 && any_condjump_p (BB_END (src))
2570 && onlyjump_p (BB_END (src)))
2571 delete_insn (BB_END (src));
2574 fprintf (dump_file, "Redirecting fallthru edge %i->%i to %i\n",
2575 e->src->index, e->dest->index, dest->index);
2576 ret = redirect_edge_succ_nodup (e, dest);
2579 ret = redirect_branch_edge (e, dest);
2581 /* We don't want simplejumps in the insn stream during cfglayout. */
2582 gcc_assert (!simplejump_p (BB_END (src)));
2584 df_set_bb_dirty (src);
2588 /* Simple wrapper as we always can redirect fallthru edges. */
2590 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2592 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2594 gcc_assert (redirected);
2598 /* Same as delete_basic_block but update cfg_layout structures. */
2601 cfg_layout_delete_block (basic_block bb)
2603 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2605 if (bb->il.rtl->header)
2607 next = BB_HEAD (bb);
2609 NEXT_INSN (prev) = bb->il.rtl->header;
2611 set_first_insn (bb->il.rtl->header);
2612 PREV_INSN (bb->il.rtl->header) = prev;
2613 insn = bb->il.rtl->header;
2614 while (NEXT_INSN (insn))
2615 insn = NEXT_INSN (insn);
2616 NEXT_INSN (insn) = next;
2617 PREV_INSN (next) = insn;
2619 next = NEXT_INSN (BB_END (bb));
2620 if (bb->il.rtl->footer)
2622 insn = bb->il.rtl->footer;
2625 if (BARRIER_P (insn))
2627 if (PREV_INSN (insn))
2628 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2630 bb->il.rtl->footer = NEXT_INSN (insn);
2631 if (NEXT_INSN (insn))
2632 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2636 insn = NEXT_INSN (insn);
2638 if (bb->il.rtl->footer)
2641 NEXT_INSN (insn) = bb->il.rtl->footer;
2642 PREV_INSN (bb->il.rtl->footer) = insn;
2643 while (NEXT_INSN (insn))
2644 insn = NEXT_INSN (insn);
2645 NEXT_INSN (insn) = next;
2647 PREV_INSN (next) = insn;
2649 set_last_insn (insn);
2652 if (bb->next_bb != EXIT_BLOCK_PTR)
2653 to = &bb->next_bb->il.rtl->header;
2655 to = &cfg_layout_function_footer;
2657 rtl_delete_block (bb);
2660 prev = NEXT_INSN (prev);
2662 prev = get_insns ();
2664 next = PREV_INSN (next);
2666 next = get_last_insn ();
2668 if (next && NEXT_INSN (next) != prev)
2670 remaints = unlink_insn_chain (prev, next);
2672 while (NEXT_INSN (insn))
2673 insn = NEXT_INSN (insn);
2674 NEXT_INSN (insn) = *to;
2676 PREV_INSN (*to) = insn;
2681 /* Return true when blocks A and B can be safely merged. */
2684 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2686 /* If we are partitioning hot/cold basic blocks, we don't want to
2687 mess up unconditional or indirect jumps that cross between hot
2690 Basic block partitioning may result in some jumps that appear to
2691 be optimizable (or blocks that appear to be mergeable), but which really
2692 must be left untouched (they are required to make it safely across
2693 partition boundaries). See the comments at the top of
2694 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2696 if (BB_PARTITION (a) != BB_PARTITION (b))
2699 /* There must be exactly one edge in between the blocks. */
2700 return (single_succ_p (a)
2701 && single_succ (a) == b
2702 && single_pred_p (b) == 1
2704 /* Must be simple edge. */
2705 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2706 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2707 /* If the jump insn has side effects, we can't kill the edge.
2708 When not optimizing, try_redirect_by_replacing_jump will
2709 not allow us to redirect an edge by replacing a table jump. */
2710 && (!JUMP_P (BB_END (a))
2711 || ((!optimize || reload_completed)
2712 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2715 /* Merge block A and B. The blocks must be mergeable. */
2718 cfg_layout_merge_blocks (basic_block a, basic_block b)
2720 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
2722 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b));
2725 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
2728 /* If there was a CODE_LABEL beginning B, delete it. */
2729 if (LABEL_P (BB_HEAD (b)))
2731 delete_insn (BB_HEAD (b));
2734 /* We should have fallthru edge in a, or we can do dummy redirection to get
2736 if (JUMP_P (BB_END (a)))
2737 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2738 gcc_assert (!JUMP_P (BB_END (a)));
2740 /* When not optimizing and the edge is the only place in RTL which holds
2741 some unique locus, emit a nop with that locus in between. */
2742 if (!optimize && EDGE_SUCC (a, 0)->goto_locus)
2744 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a));
2745 int goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2747 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
2748 insn = PREV_INSN (insn);
2749 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus))
2754 end = NEXT_INSN (BB_END (b));
2755 while (insn != end && !INSN_P (insn))
2756 insn = NEXT_INSN (insn);
2757 if (insn != end && INSN_LOCATOR (insn) != 0
2758 && locator_eq (INSN_LOCATOR (insn), goto_locus))
2763 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a);
2764 INSN_LOCATOR (BB_END (a)) = goto_locus;
2768 /* Possible line number notes should appear in between. */
2769 if (b->il.rtl->header)
2771 rtx first = BB_END (a), last;
2773 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2774 delete_insn_chain (NEXT_INSN (first), last, false);
2775 b->il.rtl->header = NULL;
2778 /* In the case basic blocks are not adjacent, move them around. */
2779 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2781 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2783 emit_insn_after_noloc (first, BB_END (a), a);
2784 /* Skip possible DELETED_LABEL insn. */
2785 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2786 first = NEXT_INSN (first);
2787 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2790 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
2791 We need to explicitly call. */
2792 update_bb_for_insn_chain (NEXT_INSN (first),
2796 delete_insn (first);
2798 /* Otherwise just re-associate the instructions. */
2803 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a);
2806 /* Skip possible DELETED_LABEL insn. */
2807 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2808 insn = NEXT_INSN (insn);
2809 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2811 BB_END (a) = BB_END (b);
2815 df_bb_delete (b->index);
2817 /* Possible tablejumps and barriers should appear after the block. */
2818 if (b->il.rtl->footer)
2820 if (!a->il.rtl->footer)
2821 a->il.rtl->footer = b->il.rtl->footer;
2824 rtx last = a->il.rtl->footer;
2826 while (NEXT_INSN (last))
2827 last = NEXT_INSN (last);
2828 NEXT_INSN (last) = b->il.rtl->footer;
2829 PREV_INSN (b->il.rtl->footer) = last;
2831 b->il.rtl->footer = NULL;
2834 /* If B was a forwarder block, propagate the locus on the edge. */
2835 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
2836 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2839 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
2845 cfg_layout_split_edge (edge e)
2847 basic_block new_bb =
2848 create_basic_block (e->src != ENTRY_BLOCK_PTR
2849 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2852 if (e->dest == EXIT_BLOCK_PTR)
2853 BB_COPY_PARTITION (new_bb, e->src);
2855 BB_COPY_PARTITION (new_bb, e->dest);
2856 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2857 redirect_edge_and_branch_force (e, new_bb);
2862 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2865 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2869 /* Return 1 if BB ends with a call, possibly followed by some
2870 instructions that must stay with the call, 0 otherwise. */
2873 rtl_block_ends_with_call_p (basic_block bb)
2875 rtx insn = BB_END (bb);
2877 while (!CALL_P (insn)
2878 && insn != BB_HEAD (bb)
2879 && (keep_with_call_p (insn)
2881 || DEBUG_INSN_P (insn)))
2882 insn = PREV_INSN (insn);
2883 return (CALL_P (insn));
2886 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2889 rtl_block_ends_with_condjump_p (const_basic_block bb)
2891 return any_condjump_p (BB_END (bb));
2894 /* Return true if we need to add fake edge to exit.
2895 Helper function for rtl_flow_call_edges_add. */
2898 need_fake_edge_p (const_rtx insn)
2904 && !SIBLING_CALL_P (insn)
2905 && !find_reg_note (insn, REG_NORETURN, NULL)
2906 && !(RTL_CONST_OR_PURE_CALL_P (insn))))
2909 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2910 && MEM_VOLATILE_P (PATTERN (insn)))
2911 || (GET_CODE (PATTERN (insn)) == PARALLEL
2912 && asm_noperands (insn) != -1
2913 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2914 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2917 /* Add fake edges to the function exit for any non constant and non noreturn
2918 calls, volatile inline assembly in the bitmap of blocks specified by
2919 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2922 The goal is to expose cases in which entering a basic block does not imply
2923 that all subsequent instructions must be executed. */
2926 rtl_flow_call_edges_add (sbitmap blocks)
2929 int blocks_split = 0;
2930 int last_bb = last_basic_block;
2931 bool check_last_block = false;
2933 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2937 check_last_block = true;
2939 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2941 /* In the last basic block, before epilogue generation, there will be
2942 a fallthru edge to EXIT. Special care is required if the last insn
2943 of the last basic block is a call because make_edge folds duplicate
2944 edges, which would result in the fallthru edge also being marked
2945 fake, which would result in the fallthru edge being removed by
2946 remove_fake_edges, which would result in an invalid CFG.
2948 Moreover, we can't elide the outgoing fake edge, since the block
2949 profiler needs to take this into account in order to solve the minimal
2950 spanning tree in the case that the call doesn't return.
2952 Handle this by adding a dummy instruction in a new last basic block. */
2953 if (check_last_block)
2955 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2956 rtx insn = BB_END (bb);
2958 /* Back up past insns that must be kept in the same block as a call. */
2959 while (insn != BB_HEAD (bb)
2960 && keep_with_call_p (insn))
2961 insn = PREV_INSN (insn);
2963 if (need_fake_edge_p (insn))
2967 e = find_edge (bb, EXIT_BLOCK_PTR);
2970 insert_insn_on_edge (gen_use (const0_rtx), e);
2971 commit_edge_insertions ();
2976 /* Now add fake edges to the function exit for any non constant
2977 calls since there is no way that we can determine if they will
2980 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
2982 basic_block bb = BASIC_BLOCK (i);
2989 if (blocks && !TEST_BIT (blocks, i))
2992 for (insn = BB_END (bb); ; insn = prev_insn)
2994 prev_insn = PREV_INSN (insn);
2995 if (need_fake_edge_p (insn))
2998 rtx split_at_insn = insn;
3000 /* Don't split the block between a call and an insn that should
3001 remain in the same block as the call. */
3003 while (split_at_insn != BB_END (bb)
3004 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3005 split_at_insn = NEXT_INSN (split_at_insn);
3007 /* The handling above of the final block before the epilogue
3008 should be enough to verify that there is no edge to the exit
3009 block in CFG already. Calling make_edge in such case would
3010 cause us to mark that edge as fake and remove it later. */
3012 #ifdef ENABLE_CHECKING
3013 if (split_at_insn == BB_END (bb))
3015 e = find_edge (bb, EXIT_BLOCK_PTR);
3016 gcc_assert (e == NULL);
3020 /* Note that the following may create a new basic block
3021 and renumber the existing basic blocks. */
3022 if (split_at_insn != BB_END (bb))
3024 e = split_block (bb, split_at_insn);
3029 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3032 if (insn == BB_HEAD (bb))
3038 verify_flow_info ();
3040 return blocks_split;
3043 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
3044 the conditional branch target, SECOND_HEAD should be the fall-thru
3045 there is no need to handle this here the loop versioning code handles
3046 this. the reason for SECON_HEAD is that it is needed for condition
3047 in trees, and this should be of the same type since it is a hook. */
3049 rtl_lv_add_condition_to_bb (basic_block first_head ,
3050 basic_block second_head ATTRIBUTE_UNUSED,
3051 basic_block cond_bb, void *comp_rtx)
3053 rtx label, seq, jump;
3054 rtx op0 = XEXP ((rtx)comp_rtx, 0);
3055 rtx op1 = XEXP ((rtx)comp_rtx, 1);
3056 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
3057 enum machine_mode mode;
3060 label = block_label (first_head);
3061 mode = GET_MODE (op0);
3062 if (mode == VOIDmode)
3063 mode = GET_MODE (op1);
3066 op0 = force_operand (op0, NULL_RTX);
3067 op1 = force_operand (op1, NULL_RTX);
3068 do_compare_rtx_and_jump (op0, op1, comp, 0,
3069 mode, NULL_RTX, NULL_RTX, label, -1);
3070 jump = get_last_insn ();
3071 JUMP_LABEL (jump) = label;
3072 LABEL_NUSES (label)++;
3076 /* Add the new cond , in the new head. */
3077 emit_insn_after(seq, BB_END(cond_bb));
3081 /* Given a block B with unconditional branch at its end, get the
3082 store the return the branch edge and the fall-thru edge in
3083 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
3085 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
3086 edge *fallthru_edge)
3088 edge e = EDGE_SUCC (b, 0);
3090 if (e->flags & EDGE_FALLTHRU)
3093 *branch_edge = EDGE_SUCC (b, 1);
3098 *fallthru_edge = EDGE_SUCC (b, 1);
3103 init_rtl_bb_info (basic_block bb)
3105 gcc_assert (!bb->il.rtl);
3106 bb->il.rtl = ggc_alloc_cleared_rtl_bb_info ();
3109 /* Returns true if it is possible to remove edge E by redirecting
3110 it to the destination of the other edge from E->src. */
3113 rtl_can_remove_branch_p (const_edge e)
3115 const_basic_block src = e->src;
3116 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3117 const_rtx insn = BB_END (src), set;
3119 /* The conditions are taken from try_redirect_by_replacing_jump. */
3120 if (target == EXIT_BLOCK_PTR)
3123 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3126 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3127 || BB_PARTITION (src) != BB_PARTITION (target))
3130 if (!onlyjump_p (insn)
3131 || tablejump_p (insn, NULL, NULL))
3134 set = single_set (insn);
3135 if (!set || side_effects_p (set))
3141 /* Implementation of CFG manipulation for linearized RTL. */
3142 struct cfg_hooks rtl_cfg_hooks = {
3144 rtl_verify_flow_info,
3146 rtl_create_basic_block,
3147 rtl_redirect_edge_and_branch,
3148 rtl_redirect_edge_and_branch_force,
3149 rtl_can_remove_branch_p,
3152 rtl_move_block_after,
3153 rtl_can_merge_blocks, /* can_merge_blocks_p */
3157 NULL, /* can_duplicate_block_p */
3158 NULL, /* duplicate_block */
3160 rtl_make_forwarder_block,
3161 rtl_tidy_fallthru_edge,
3162 rtl_force_nonfallthru,
3163 rtl_block_ends_with_call_p,
3164 rtl_block_ends_with_condjump_p,
3165 rtl_flow_call_edges_add,
3166 NULL, /* execute_on_growing_pred */
3167 NULL, /* execute_on_shrinking_pred */
3168 NULL, /* duplicate loop for trees */
3169 NULL, /* lv_add_condition_to_bb */
3170 NULL, /* lv_adjust_loop_header_phi*/
3171 NULL, /* extract_cond_bb_edges */
3172 NULL /* flush_pending_stmts */
3175 /* Implementation of CFG manipulation for cfg layout RTL, where
3176 basic block connected via fallthru edges does not have to be adjacent.
3177 This representation will hopefully become the default one in future
3178 version of the compiler. */
3180 /* We do not want to declare these functions in a header file, since they
3181 should only be used through the cfghooks interface, and we do not want to
3182 move them here since it would require also moving quite a lot of related
3183 code. They are in cfglayout.c. */
3184 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3185 extern basic_block cfg_layout_duplicate_bb (basic_block);
3187 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3189 rtl_verify_flow_info_1,
3191 cfg_layout_create_basic_block,
3192 cfg_layout_redirect_edge_and_branch,
3193 cfg_layout_redirect_edge_and_branch_force,
3194 rtl_can_remove_branch_p,
3195 cfg_layout_delete_block,
3196 cfg_layout_split_block,
3197 rtl_move_block_after,
3198 cfg_layout_can_merge_blocks_p,
3199 cfg_layout_merge_blocks,
3202 cfg_layout_can_duplicate_bb_p,
3203 cfg_layout_duplicate_bb,
3204 cfg_layout_split_edge,
3205 rtl_make_forwarder_block,
3206 NULL, /* tidy_fallthru_edge */
3207 rtl_force_nonfallthru,
3208 rtl_block_ends_with_call_p,
3209 rtl_block_ends_with_condjump_p,
3210 rtl_flow_call_edges_add,
3211 NULL, /* execute_on_growing_pred */
3212 NULL, /* execute_on_shrinking_pred */
3213 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3214 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3215 NULL, /* lv_adjust_loop_header_phi*/
3216 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3217 NULL /* flush_pending_stmts */