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))
1667 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1672 fprintf (outf, ";; Start of basic block (");
1673 FOR_EACH_EDGE (e, ei, bb->preds)
1674 fprintf (outf, " %d", e->src->index);
1675 fprintf (outf, ") -> %d\n", bb->index);
1679 df_dump_top (bb, outf);
1682 FOR_EACH_EDGE (e, ei, bb->preds)
1684 fputs (";; Pred edge ", outf);
1685 dump_edge_info (outf, e, 0);
1690 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1691 && !NOTE_P (tmp_rtx)
1692 && !BARRIER_P (tmp_rtx))
1693 fprintf (outf, ";; Insn is not within a basic block\n");
1694 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1695 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1697 did_output = print_rtl_single (outf, tmp_rtx);
1699 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1704 fprintf (outf, ";; End of basic block %d -> (", bb->index);
1705 FOR_EACH_EDGE (e, ei, bb->succs)
1706 fprintf (outf, " %d", e->dest->index);
1707 fprintf (outf, ")\n");
1711 df_dump_bottom (bb, outf);
1715 FOR_EACH_EDGE (e, ei, bb->succs)
1717 fputs (";; Succ edge ", outf);
1718 dump_edge_info (outf, e, 1);
1731 if (crtl->epilogue_delay_list != 0)
1733 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1734 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0;
1735 tmp_rtx = XEXP (tmp_rtx, 1))
1736 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1741 update_br_prob_note (basic_block bb)
1744 if (!JUMP_P (BB_END (bb)))
1746 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1747 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1749 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1752 /* Get the last insn associated with block BB (that includes barriers and
1753 tablejumps after BB). */
1755 get_last_bb_insn (basic_block bb)
1758 rtx end = BB_END (bb);
1760 /* Include any jump table following the basic block. */
1761 if (tablejump_p (end, NULL, &tmp))
1764 /* Include any barriers that may follow the basic block. */
1765 tmp = next_nonnote_insn_bb (end);
1766 while (tmp && BARRIER_P (tmp))
1769 tmp = next_nonnote_insn_bb (end);
1775 /* Verify the CFG and RTL consistency common for both underlying RTL and
1778 Currently it does following checks:
1780 - overlapping of basic blocks
1781 - insns with wrong BLOCK_FOR_INSN pointers
1782 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1783 - tails of basic blocks (ensure that boundary is necessary)
1784 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1785 and NOTE_INSN_BASIC_BLOCK
1786 - verify that no fall_thru edge crosses hot/cold partition boundaries
1787 - verify that there are no pending RTL branch predictions
1789 In future it can be extended check a lot of other stuff as well
1790 (reachability of basic blocks, life information, etc. etc.). */
1793 rtl_verify_flow_info_1 (void)
1799 /* Check the general integrity of the basic blocks. */
1800 FOR_EACH_BB_REVERSE (bb)
1804 if (!(bb->flags & BB_RTL))
1806 error ("BB_RTL flag not set for block %d", bb->index);
1810 FOR_BB_INSNS (bb, insn)
1811 if (BLOCK_FOR_INSN (insn) != bb)
1813 error ("insn %d basic block pointer is %d, should be %d",
1815 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1820 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1821 if (!BARRIER_P (insn)
1822 && BLOCK_FOR_INSN (insn) != NULL)
1824 error ("insn %d in header of bb %d has non-NULL basic block",
1825 INSN_UID (insn), bb->index);
1828 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1829 if (!BARRIER_P (insn)
1830 && BLOCK_FOR_INSN (insn) != NULL)
1832 error ("insn %d in footer of bb %d has non-NULL basic block",
1833 INSN_UID (insn), bb->index);
1838 /* Now check the basic blocks (boundaries etc.) */
1839 FOR_EACH_BB_REVERSE (bb)
1841 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1842 edge e, fallthru = NULL;
1846 if (JUMP_P (BB_END (bb))
1847 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1848 && EDGE_COUNT (bb->succs) >= 2
1849 && any_condjump_p (BB_END (bb)))
1851 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1852 && profile_status != PROFILE_ABSENT)
1854 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1855 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1859 FOR_EACH_EDGE (e, ei, bb->succs)
1861 if (e->flags & EDGE_FALLTHRU)
1863 n_fallthru++, fallthru = e;
1864 if ((e->flags & EDGE_CROSSING)
1865 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1866 && e->src != ENTRY_BLOCK_PTR
1867 && e->dest != EXIT_BLOCK_PTR))
1869 error ("fallthru edge crosses section boundary (bb %i)",
1875 if ((e->flags & ~(EDGE_DFS_BACK
1877 | EDGE_IRREDUCIBLE_LOOP
1879 | EDGE_CROSSING)) == 0)
1882 if (e->flags & EDGE_ABNORMAL_CALL)
1885 if (e->flags & EDGE_EH)
1887 else if (e->flags & EDGE_ABNORMAL)
1891 if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1893 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1898 error ("too many eh edges %i", bb->index);
1902 && (!JUMP_P (BB_END (bb))
1903 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1904 || any_condjump_p (BB_END (bb))))))
1906 error ("too many outgoing branch edges from bb %i", bb->index);
1909 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1911 error ("fallthru edge after unconditional jump %i", bb->index);
1914 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1916 error ("wrong number of branch edges after unconditional jump %i",
1920 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1921 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1923 error ("wrong amount of branch edges after conditional jump %i",
1927 if (n_call && !CALL_P (BB_END (bb)))
1929 error ("call edges for non-call insn in bb %i", bb->index);
1933 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1934 && (!JUMP_P (BB_END (bb))
1935 || any_condjump_p (BB_END (bb))
1936 || any_uncondjump_p (BB_END (bb))))
1938 error ("abnormal edges for no purpose in bb %i", bb->index);
1942 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1943 /* We may have a barrier inside a basic block before dead code
1944 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1945 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1948 if (! BLOCK_FOR_INSN (x))
1950 ("insn %d inside basic block %d but block_for_insn is NULL",
1951 INSN_UID (x), bb->index);
1954 ("insn %d inside basic block %d but block_for_insn is %i",
1955 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1960 /* OK pointers are correct. Now check the header of basic
1961 block. It ought to contain optional CODE_LABEL followed
1962 by NOTE_BASIC_BLOCK. */
1966 if (BB_END (bb) == x)
1968 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1976 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1978 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1983 if (BB_END (bb) == x)
1984 /* Do checks for empty blocks here. */
1987 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1989 if (NOTE_INSN_BASIC_BLOCK_P (x))
1991 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1992 INSN_UID (x), bb->index);
1996 if (x == BB_END (bb))
1999 if (control_flow_insn_p (x))
2001 error ("in basic block %d:", bb->index);
2002 fatal_insn ("flow control insn inside a basic block", x);
2011 /* Verify the CFG and RTL consistency common for both underlying RTL and
2014 Currently it does following checks:
2015 - all checks of rtl_verify_flow_info_1
2016 - test head/end pointers
2017 - check that all insns are in the basic blocks
2018 (except the switch handling code, barriers and notes)
2019 - check that all returns are followed by barriers
2020 - check that all fallthru edge points to the adjacent blocks. */
2023 rtl_verify_flow_info (void)
2026 int err = rtl_verify_flow_info_1 ();
2028 rtx last_head = get_last_insn ();
2029 basic_block *bb_info;
2031 const rtx rtx_first = get_insns ();
2032 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2033 const int max_uid = get_max_uid ();
2035 bb_info = XCNEWVEC (basic_block, max_uid);
2037 FOR_EACH_BB_REVERSE (bb)
2040 rtx head = BB_HEAD (bb);
2041 rtx end = BB_END (bb);
2043 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2045 /* Verify the end of the basic block is in the INSN chain. */
2049 /* And that the code outside of basic blocks has NULL bb field. */
2051 && BLOCK_FOR_INSN (x) != NULL)
2053 error ("insn %d outside of basic blocks has non-NULL bb field",
2061 error ("end insn %d for block %d not found in the insn stream",
2062 INSN_UID (end), bb->index);
2066 /* Work backwards from the end to the head of the basic block
2067 to verify the head is in the RTL chain. */
2068 for (; x != NULL_RTX; x = PREV_INSN (x))
2070 /* While walking over the insn chain, verify insns appear
2071 in only one basic block. */
2072 if (bb_info[INSN_UID (x)] != NULL)
2074 error ("insn %d is in multiple basic blocks (%d and %d)",
2075 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
2079 bb_info[INSN_UID (x)] = bb;
2086 error ("head insn %d for block %d not found in the insn stream",
2087 INSN_UID (head), bb->index);
2091 last_head = PREV_INSN (x);
2093 e = find_fallthru_edge (bb->succs);
2098 /* Ensure existence of barrier in BB with no fallthru edges. */
2099 for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn))
2101 if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn))
2103 error ("missing barrier after block %i", bb->index);
2107 if (BARRIER_P (insn))
2111 else if (e->src != ENTRY_BLOCK_PTR
2112 && e->dest != EXIT_BLOCK_PTR)
2116 if (e->src->next_bb != e->dest)
2119 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2120 e->src->index, e->dest->index);
2124 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2125 insn = NEXT_INSN (insn))
2126 if (BARRIER_P (insn) || INSN_P (insn))
2128 error ("verify_flow_info: Incorrect fallthru %i->%i",
2129 e->src->index, e->dest->index);
2130 fatal_insn ("wrong insn in the fallthru edge", insn);
2136 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2138 /* Check that the code before the first basic block has NULL
2141 && BLOCK_FOR_INSN (x) != NULL)
2143 error ("insn %d outside of basic blocks has non-NULL bb field",
2151 last_bb_seen = ENTRY_BLOCK_PTR;
2153 for (x = rtx_first; x; x = NEXT_INSN (x))
2155 if (NOTE_INSN_BASIC_BLOCK_P (x))
2157 bb = NOTE_BASIC_BLOCK (x);
2160 if (bb != last_bb_seen->next_bb)
2161 internal_error ("basic blocks not laid down consecutively");
2163 curr_bb = last_bb_seen = bb;
2168 switch (GET_CODE (x))
2175 /* An addr_vec is placed outside any basic block. */
2177 && JUMP_TABLE_DATA_P (NEXT_INSN (x)))
2180 /* But in any case, non-deletable labels can appear anywhere. */
2184 fatal_insn ("insn outside basic block", x);
2189 && returnjump_p (x) && ! condjump_p (x)
2190 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2191 fatal_insn ("return not followed by barrier", x);
2192 if (curr_bb && x == BB_END (curr_bb))
2196 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2198 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2199 num_bb_notes, n_basic_blocks);
2204 /* Assume that the preceding pass has possibly eliminated jump instructions
2205 or converted the unconditional jumps. Eliminate the edges from CFG.
2206 Return true if any edges are eliminated. */
2209 purge_dead_edges (basic_block bb)
2212 rtx insn = BB_END (bb), note;
2213 bool purged = false;
2217 if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb))
2219 insn = PREV_INSN (insn);
2220 while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb));
2222 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2223 if (NONJUMP_INSN_P (insn)
2224 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2228 if (! may_trap_p (PATTERN (insn))
2229 || ((eqnote = find_reg_equal_equiv_note (insn))
2230 && ! may_trap_p (XEXP (eqnote, 0))))
2231 remove_note (insn, note);
2234 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2235 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2237 bool remove = false;
2239 /* There are three types of edges we need to handle correctly here: EH
2240 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2241 latter can appear when nonlocal gotos are used. */
2242 if (e->flags & EDGE_ABNORMAL_CALL)
2246 else if (can_nonlocal_goto (insn))
2248 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2253 else if (e->flags & EDGE_EH)
2254 remove = !can_throw_internal (insn);
2259 df_set_bb_dirty (bb);
2272 /* We do care only about conditional jumps and simplejumps. */
2273 if (!any_condjump_p (insn)
2274 && !returnjump_p (insn)
2275 && !simplejump_p (insn))
2278 /* Branch probability/prediction notes are defined only for
2279 condjumps. We've possibly turned condjump into simplejump. */
2280 if (simplejump_p (insn))
2282 note = find_reg_note (insn, REG_BR_PROB, NULL);
2284 remove_note (insn, note);
2285 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2286 remove_note (insn, note);
2289 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2291 /* Avoid abnormal flags to leak from computed jumps turned
2292 into simplejumps. */
2294 e->flags &= ~EDGE_ABNORMAL;
2296 /* See if this edge is one we should keep. */
2297 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2298 /* A conditional jump can fall through into the next
2299 block, so we should keep the edge. */
2304 else if (e->dest != EXIT_BLOCK_PTR
2305 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2306 /* If the destination block is the target of the jump,
2312 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2313 /* If the destination block is the exit block, and this
2314 instruction is a return, then keep the edge. */
2319 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2320 /* Keep the edges that correspond to exceptions thrown by
2321 this instruction and rematerialize the EDGE_ABNORMAL
2322 flag we just cleared above. */
2324 e->flags |= EDGE_ABNORMAL;
2329 /* We do not need this edge. */
2330 df_set_bb_dirty (bb);
2335 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2339 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2344 /* Redistribute probabilities. */
2345 if (single_succ_p (bb))
2347 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2348 single_succ_edge (bb)->count = bb->count;
2352 note = find_reg_note (insn, REG_BR_PROB, NULL);
2356 b = BRANCH_EDGE (bb);
2357 f = FALLTHRU_EDGE (bb);
2358 b->probability = INTVAL (XEXP (note, 0));
2359 f->probability = REG_BR_PROB_BASE - b->probability;
2360 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2361 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2366 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2368 /* First, there should not be any EH or ABCALL edges resulting
2369 from non-local gotos and the like. If there were, we shouldn't
2370 have created the sibcall in the first place. Second, there
2371 should of course never have been a fallthru edge. */
2372 gcc_assert (single_succ_p (bb));
2373 gcc_assert (single_succ_edge (bb)->flags
2374 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2379 /* If we don't see a jump insn, we don't know exactly why the block would
2380 have been broken at this point. Look for a simple, non-fallthru edge,
2381 as these are only created by conditional branches. If we find such an
2382 edge we know that there used to be a jump here and can then safely
2383 remove all non-fallthru edges. */
2385 FOR_EACH_EDGE (e, ei, bb->succs)
2386 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2395 /* Remove all but the fake and fallthru edges. The fake edge may be
2396 the only successor for this block in the case of noreturn
2398 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2400 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2402 df_set_bb_dirty (bb);
2410 gcc_assert (single_succ_p (bb));
2412 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2413 single_succ_edge (bb)->count = bb->count;
2416 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2421 /* Search all basic blocks for potentially dead edges and purge them. Return
2422 true if some edge has been eliminated. */
2425 purge_all_dead_edges (void)
2432 bool purged_here = purge_dead_edges (bb);
2434 purged |= purged_here;
2440 /* This is used by a few passes that emit some instructions after abnormal
2441 calls, moving the basic block's end, while they in fact do want to emit
2442 them on the fallthru edge. Look for abnormal call edges, find backward
2443 the call in the block and insert the instructions on the edge instead.
2445 Similarly, handle instructions throwing exceptions internally.
2447 Return true when instructions have been found and inserted on edges. */
2450 fixup_abnormal_edges (void)
2452 bool inserted = false;
2460 /* Look for cases we are interested in - calls or instructions causing
2462 FOR_EACH_EDGE (e, ei, bb->succs)
2463 if ((e->flags & EDGE_ABNORMAL_CALL)
2464 || ((e->flags & (EDGE_ABNORMAL | EDGE_EH))
2465 == (EDGE_ABNORMAL | EDGE_EH)))
2468 if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb)))
2472 /* Get past the new insns generated. Allow notes, as the insns
2473 may be already deleted. */
2475 while ((NONJUMP_INSN_P (insn) || NOTE_P (insn))
2476 && !can_throw_internal (insn)
2477 && insn != BB_HEAD (bb))
2478 insn = PREV_INSN (insn);
2480 if (CALL_P (insn) || can_throw_internal (insn))
2484 e = find_fallthru_edge (bb->succs);
2486 stop = NEXT_INSN (BB_END (bb));
2489 for (insn = NEXT_INSN (insn); insn != stop; insn = next)
2491 next = NEXT_INSN (insn);
2496 /* Sometimes there's still the return value USE.
2497 If it's placed after a trapping call (i.e. that
2498 call is the last insn anyway), we have no fallthru
2499 edge. Simply delete this use and don't try to insert
2500 on the non-existent edge. */
2501 if (GET_CODE (PATTERN (insn)) != USE)
2503 /* We're not deleting it, we're moving it. */
2504 INSN_DELETED_P (insn) = 0;
2505 PREV_INSN (insn) = NULL_RTX;
2506 NEXT_INSN (insn) = NULL_RTX;
2508 insert_insn_on_edge (insn, e);
2512 else if (!BARRIER_P (insn))
2513 set_block_for_insn (insn, NULL);
2517 /* It may be that we don't find any trapping insn. In this
2518 case we discovered quite late that the insn that had been
2519 marked as can_throw_internal in fact couldn't trap at all.
2520 So we should in fact delete the EH edges out of the block. */
2522 purge_dead_edges (bb);
2529 /* Same as split_block but update cfg_layout structures. */
2532 cfg_layout_split_block (basic_block bb, void *insnp)
2534 rtx insn = (rtx) insnp;
2535 basic_block new_bb = rtl_split_block (bb, insn);
2537 new_bb->il.rtl->footer = bb->il.rtl->footer;
2538 bb->il.rtl->footer = NULL;
2543 /* Redirect Edge to DEST. */
2545 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2547 basic_block src = e->src;
2550 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2553 if (e->dest == dest)
2556 if (e->src != ENTRY_BLOCK_PTR
2557 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2559 df_set_bb_dirty (src);
2563 if (e->src == ENTRY_BLOCK_PTR
2564 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2567 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2568 e->src->index, dest->index);
2570 df_set_bb_dirty (e->src);
2571 redirect_edge_succ (e, dest);
2575 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2576 in the case the basic block appears to be in sequence. Avoid this
2579 if (e->flags & EDGE_FALLTHRU)
2581 /* Redirect any branch edges unified with the fallthru one. */
2582 if (JUMP_P (BB_END (src))
2583 && label_is_jump_target_p (BB_HEAD (e->dest),
2589 fprintf (dump_file, "Fallthru edge unified with branch "
2590 "%i->%i redirected to %i\n",
2591 e->src->index, e->dest->index, dest->index);
2592 e->flags &= ~EDGE_FALLTHRU;
2593 redirected = redirect_branch_edge (e, dest);
2594 gcc_assert (redirected);
2595 redirected->flags |= EDGE_FALLTHRU;
2596 df_set_bb_dirty (redirected->src);
2599 /* In case we are redirecting fallthru edge to the branch edge
2600 of conditional jump, remove it. */
2601 if (EDGE_COUNT (src->succs) == 2)
2603 /* Find the edge that is different from E. */
2604 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2607 && any_condjump_p (BB_END (src))
2608 && onlyjump_p (BB_END (src)))
2609 delete_insn (BB_END (src));
2612 fprintf (dump_file, "Redirecting fallthru edge %i->%i to %i\n",
2613 e->src->index, e->dest->index, dest->index);
2614 ret = redirect_edge_succ_nodup (e, dest);
2617 ret = redirect_branch_edge (e, dest);
2619 /* We don't want simplejumps in the insn stream during cfglayout. */
2620 gcc_assert (!simplejump_p (BB_END (src)));
2622 df_set_bb_dirty (src);
2626 /* Simple wrapper as we always can redirect fallthru edges. */
2628 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2630 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2632 gcc_assert (redirected);
2636 /* Same as delete_basic_block but update cfg_layout structures. */
2639 cfg_layout_delete_block (basic_block bb)
2641 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2643 if (bb->il.rtl->header)
2645 next = BB_HEAD (bb);
2647 NEXT_INSN (prev) = bb->il.rtl->header;
2649 set_first_insn (bb->il.rtl->header);
2650 PREV_INSN (bb->il.rtl->header) = prev;
2651 insn = bb->il.rtl->header;
2652 while (NEXT_INSN (insn))
2653 insn = NEXT_INSN (insn);
2654 NEXT_INSN (insn) = next;
2655 PREV_INSN (next) = insn;
2657 next = NEXT_INSN (BB_END (bb));
2658 if (bb->il.rtl->footer)
2660 insn = bb->il.rtl->footer;
2663 if (BARRIER_P (insn))
2665 if (PREV_INSN (insn))
2666 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2668 bb->il.rtl->footer = NEXT_INSN (insn);
2669 if (NEXT_INSN (insn))
2670 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2674 insn = NEXT_INSN (insn);
2676 if (bb->il.rtl->footer)
2679 NEXT_INSN (insn) = bb->il.rtl->footer;
2680 PREV_INSN (bb->il.rtl->footer) = insn;
2681 while (NEXT_INSN (insn))
2682 insn = NEXT_INSN (insn);
2683 NEXT_INSN (insn) = next;
2685 PREV_INSN (next) = insn;
2687 set_last_insn (insn);
2690 if (bb->next_bb != EXIT_BLOCK_PTR)
2691 to = &bb->next_bb->il.rtl->header;
2693 to = &cfg_layout_function_footer;
2695 rtl_delete_block (bb);
2698 prev = NEXT_INSN (prev);
2700 prev = get_insns ();
2702 next = PREV_INSN (next);
2704 next = get_last_insn ();
2706 if (next && NEXT_INSN (next) != prev)
2708 remaints = unlink_insn_chain (prev, next);
2710 while (NEXT_INSN (insn))
2711 insn = NEXT_INSN (insn);
2712 NEXT_INSN (insn) = *to;
2714 PREV_INSN (*to) = insn;
2719 /* Return true when blocks A and B can be safely merged. */
2722 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2724 /* If we are partitioning hot/cold basic blocks, we don't want to
2725 mess up unconditional or indirect jumps that cross between hot
2728 Basic block partitioning may result in some jumps that appear to
2729 be optimizable (or blocks that appear to be mergeable), but which really
2730 must be left untouched (they are required to make it safely across
2731 partition boundaries). See the comments at the top of
2732 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2734 if (BB_PARTITION (a) != BB_PARTITION (b))
2737 /* There must be exactly one edge in between the blocks. */
2738 return (single_succ_p (a)
2739 && single_succ (a) == b
2740 && single_pred_p (b) == 1
2742 /* Must be simple edge. */
2743 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2744 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2745 /* If the jump insn has side effects, we can't kill the edge.
2746 When not optimizing, try_redirect_by_replacing_jump will
2747 not allow us to redirect an edge by replacing a table jump. */
2748 && (!JUMP_P (BB_END (a))
2749 || ((!optimize || reload_completed)
2750 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2753 /* Merge block A and B. The blocks must be mergeable. */
2756 cfg_layout_merge_blocks (basic_block a, basic_block b)
2758 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
2760 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b));
2763 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
2766 /* If there was a CODE_LABEL beginning B, delete it. */
2767 if (LABEL_P (BB_HEAD (b)))
2769 delete_insn (BB_HEAD (b));
2772 /* We should have fallthru edge in a, or we can do dummy redirection to get
2774 if (JUMP_P (BB_END (a)))
2775 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2776 gcc_assert (!JUMP_P (BB_END (a)));
2778 /* When not optimizing and the edge is the only place in RTL which holds
2779 some unique locus, emit a nop with that locus in between. */
2780 if (!optimize && EDGE_SUCC (a, 0)->goto_locus)
2782 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a));
2783 int goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2785 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
2786 insn = PREV_INSN (insn);
2787 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus))
2792 end = NEXT_INSN (BB_END (b));
2793 while (insn != end && !INSN_P (insn))
2794 insn = NEXT_INSN (insn);
2795 if (insn != end && INSN_LOCATOR (insn) != 0
2796 && locator_eq (INSN_LOCATOR (insn), goto_locus))
2801 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a);
2802 INSN_LOCATOR (BB_END (a)) = goto_locus;
2806 /* Possible line number notes should appear in between. */
2807 if (b->il.rtl->header)
2809 rtx first = BB_END (a), last;
2811 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2812 delete_insn_chain (NEXT_INSN (first), last, false);
2813 b->il.rtl->header = NULL;
2816 /* In the case basic blocks are not adjacent, move them around. */
2817 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2819 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2821 emit_insn_after_noloc (first, BB_END (a), a);
2822 /* Skip possible DELETED_LABEL insn. */
2823 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2824 first = NEXT_INSN (first);
2825 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2828 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
2829 We need to explicitly call. */
2830 update_bb_for_insn_chain (NEXT_INSN (first),
2834 delete_insn (first);
2836 /* Otherwise just re-associate the instructions. */
2841 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a);
2844 /* Skip possible DELETED_LABEL insn. */
2845 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2846 insn = NEXT_INSN (insn);
2847 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2849 BB_END (a) = BB_END (b);
2853 df_bb_delete (b->index);
2855 /* Possible tablejumps and barriers should appear after the block. */
2856 if (b->il.rtl->footer)
2858 if (!a->il.rtl->footer)
2859 a->il.rtl->footer = b->il.rtl->footer;
2862 rtx last = a->il.rtl->footer;
2864 while (NEXT_INSN (last))
2865 last = NEXT_INSN (last);
2866 NEXT_INSN (last) = b->il.rtl->footer;
2867 PREV_INSN (b->il.rtl->footer) = last;
2869 b->il.rtl->footer = NULL;
2872 /* If B was a forwarder block, propagate the locus on the edge. */
2873 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
2874 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2877 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
2883 cfg_layout_split_edge (edge e)
2885 basic_block new_bb =
2886 create_basic_block (e->src != ENTRY_BLOCK_PTR
2887 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2890 if (e->dest == EXIT_BLOCK_PTR)
2891 BB_COPY_PARTITION (new_bb, e->src);
2893 BB_COPY_PARTITION (new_bb, e->dest);
2894 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2895 redirect_edge_and_branch_force (e, new_bb);
2900 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2903 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2907 /* Return 1 if BB ends with a call, possibly followed by some
2908 instructions that must stay with the call, 0 otherwise. */
2911 rtl_block_ends_with_call_p (basic_block bb)
2913 rtx insn = BB_END (bb);
2915 while (!CALL_P (insn)
2916 && insn != BB_HEAD (bb)
2917 && (keep_with_call_p (insn)
2919 || DEBUG_INSN_P (insn)))
2920 insn = PREV_INSN (insn);
2921 return (CALL_P (insn));
2924 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2927 rtl_block_ends_with_condjump_p (const_basic_block bb)
2929 return any_condjump_p (BB_END (bb));
2932 /* Return true if we need to add fake edge to exit.
2933 Helper function for rtl_flow_call_edges_add. */
2936 need_fake_edge_p (const_rtx insn)
2942 && !SIBLING_CALL_P (insn)
2943 && !find_reg_note (insn, REG_NORETURN, NULL)
2944 && !(RTL_CONST_OR_PURE_CALL_P (insn))))
2947 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2948 && MEM_VOLATILE_P (PATTERN (insn)))
2949 || (GET_CODE (PATTERN (insn)) == PARALLEL
2950 && asm_noperands (insn) != -1
2951 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2952 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2955 /* Add fake edges to the function exit for any non constant and non noreturn
2956 calls, volatile inline assembly in the bitmap of blocks specified by
2957 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2960 The goal is to expose cases in which entering a basic block does not imply
2961 that all subsequent instructions must be executed. */
2964 rtl_flow_call_edges_add (sbitmap blocks)
2967 int blocks_split = 0;
2968 int last_bb = last_basic_block;
2969 bool check_last_block = false;
2971 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2975 check_last_block = true;
2977 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2979 /* In the last basic block, before epilogue generation, there will be
2980 a fallthru edge to EXIT. Special care is required if the last insn
2981 of the last basic block is a call because make_edge folds duplicate
2982 edges, which would result in the fallthru edge also being marked
2983 fake, which would result in the fallthru edge being removed by
2984 remove_fake_edges, which would result in an invalid CFG.
2986 Moreover, we can't elide the outgoing fake edge, since the block
2987 profiler needs to take this into account in order to solve the minimal
2988 spanning tree in the case that the call doesn't return.
2990 Handle this by adding a dummy instruction in a new last basic block. */
2991 if (check_last_block)
2993 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2994 rtx insn = BB_END (bb);
2996 /* Back up past insns that must be kept in the same block as a call. */
2997 while (insn != BB_HEAD (bb)
2998 && keep_with_call_p (insn))
2999 insn = PREV_INSN (insn);
3001 if (need_fake_edge_p (insn))
3005 e = find_edge (bb, EXIT_BLOCK_PTR);
3008 insert_insn_on_edge (gen_use (const0_rtx), e);
3009 commit_edge_insertions ();
3014 /* Now add fake edges to the function exit for any non constant
3015 calls since there is no way that we can determine if they will
3018 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
3020 basic_block bb = BASIC_BLOCK (i);
3027 if (blocks && !TEST_BIT (blocks, i))
3030 for (insn = BB_END (bb); ; insn = prev_insn)
3032 prev_insn = PREV_INSN (insn);
3033 if (need_fake_edge_p (insn))
3036 rtx split_at_insn = insn;
3038 /* Don't split the block between a call and an insn that should
3039 remain in the same block as the call. */
3041 while (split_at_insn != BB_END (bb)
3042 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3043 split_at_insn = NEXT_INSN (split_at_insn);
3045 /* The handling above of the final block before the epilogue
3046 should be enough to verify that there is no edge to the exit
3047 block in CFG already. Calling make_edge in such case would
3048 cause us to mark that edge as fake and remove it later. */
3050 #ifdef ENABLE_CHECKING
3051 if (split_at_insn == BB_END (bb))
3053 e = find_edge (bb, EXIT_BLOCK_PTR);
3054 gcc_assert (e == NULL);
3058 /* Note that the following may create a new basic block
3059 and renumber the existing basic blocks. */
3060 if (split_at_insn != BB_END (bb))
3062 e = split_block (bb, split_at_insn);
3067 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3070 if (insn == BB_HEAD (bb))
3076 verify_flow_info ();
3078 return blocks_split;
3081 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
3082 the conditional branch target, SECOND_HEAD should be the fall-thru
3083 there is no need to handle this here the loop versioning code handles
3084 this. the reason for SECON_HEAD is that it is needed for condition
3085 in trees, and this should be of the same type since it is a hook. */
3087 rtl_lv_add_condition_to_bb (basic_block first_head ,
3088 basic_block second_head ATTRIBUTE_UNUSED,
3089 basic_block cond_bb, void *comp_rtx)
3091 rtx label, seq, jump;
3092 rtx op0 = XEXP ((rtx)comp_rtx, 0);
3093 rtx op1 = XEXP ((rtx)comp_rtx, 1);
3094 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
3095 enum machine_mode mode;
3098 label = block_label (first_head);
3099 mode = GET_MODE (op0);
3100 if (mode == VOIDmode)
3101 mode = GET_MODE (op1);
3104 op0 = force_operand (op0, NULL_RTX);
3105 op1 = force_operand (op1, NULL_RTX);
3106 do_compare_rtx_and_jump (op0, op1, comp, 0,
3107 mode, NULL_RTX, NULL_RTX, label, -1);
3108 jump = get_last_insn ();
3109 JUMP_LABEL (jump) = label;
3110 LABEL_NUSES (label)++;
3114 /* Add the new cond , in the new head. */
3115 emit_insn_after(seq, BB_END(cond_bb));
3119 /* Given a block B with unconditional branch at its end, get the
3120 store the return the branch edge and the fall-thru edge in
3121 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
3123 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
3124 edge *fallthru_edge)
3126 edge e = EDGE_SUCC (b, 0);
3128 if (e->flags & EDGE_FALLTHRU)
3131 *branch_edge = EDGE_SUCC (b, 1);
3136 *fallthru_edge = EDGE_SUCC (b, 1);
3141 init_rtl_bb_info (basic_block bb)
3143 gcc_assert (!bb->il.rtl);
3144 bb->il.rtl = ggc_alloc_cleared_rtl_bb_info ();
3147 /* Returns true if it is possible to remove edge E by redirecting
3148 it to the destination of the other edge from E->src. */
3151 rtl_can_remove_branch_p (const_edge e)
3153 const_basic_block src = e->src;
3154 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3155 const_rtx insn = BB_END (src), set;
3157 /* The conditions are taken from try_redirect_by_replacing_jump. */
3158 if (target == EXIT_BLOCK_PTR)
3161 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3164 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3165 || BB_PARTITION (src) != BB_PARTITION (target))
3168 if (!onlyjump_p (insn)
3169 || tablejump_p (insn, NULL, NULL))
3172 set = single_set (insn);
3173 if (!set || side_effects_p (set))
3179 /* Implementation of CFG manipulation for linearized RTL. */
3180 struct cfg_hooks rtl_cfg_hooks = {
3182 rtl_verify_flow_info,
3184 rtl_create_basic_block,
3185 rtl_redirect_edge_and_branch,
3186 rtl_redirect_edge_and_branch_force,
3187 rtl_can_remove_branch_p,
3190 rtl_move_block_after,
3191 rtl_can_merge_blocks, /* can_merge_blocks_p */
3195 NULL, /* can_duplicate_block_p */
3196 NULL, /* duplicate_block */
3198 rtl_make_forwarder_block,
3199 rtl_tidy_fallthru_edge,
3200 rtl_force_nonfallthru,
3201 rtl_block_ends_with_call_p,
3202 rtl_block_ends_with_condjump_p,
3203 rtl_flow_call_edges_add,
3204 NULL, /* execute_on_growing_pred */
3205 NULL, /* execute_on_shrinking_pred */
3206 NULL, /* duplicate loop for trees */
3207 NULL, /* lv_add_condition_to_bb */
3208 NULL, /* lv_adjust_loop_header_phi*/
3209 NULL, /* extract_cond_bb_edges */
3210 NULL /* flush_pending_stmts */
3213 /* Implementation of CFG manipulation for cfg layout RTL, where
3214 basic block connected via fallthru edges does not have to be adjacent.
3215 This representation will hopefully become the default one in future
3216 version of the compiler. */
3218 /* We do not want to declare these functions in a header file, since they
3219 should only be used through the cfghooks interface, and we do not want to
3220 move them here since it would require also moving quite a lot of related
3221 code. They are in cfglayout.c. */
3222 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3223 extern basic_block cfg_layout_duplicate_bb (basic_block);
3225 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3227 rtl_verify_flow_info_1,
3229 cfg_layout_create_basic_block,
3230 cfg_layout_redirect_edge_and_branch,
3231 cfg_layout_redirect_edge_and_branch_force,
3232 rtl_can_remove_branch_p,
3233 cfg_layout_delete_block,
3234 cfg_layout_split_block,
3235 rtl_move_block_after,
3236 cfg_layout_can_merge_blocks_p,
3237 cfg_layout_merge_blocks,
3240 cfg_layout_can_duplicate_bb_p,
3241 cfg_layout_duplicate_bb,
3242 cfg_layout_split_edge,
3243 rtl_make_forwarder_block,
3244 NULL, /* tidy_fallthru_edge */
3245 rtl_force_nonfallthru,
3246 rtl_block_ends_with_call_p,
3247 rtl_block_ends_with_condjump_p,
3248 rtl_flow_call_edges_add,
3249 NULL, /* execute_on_growing_pred */
3250 NULL, /* execute_on_shrinking_pred */
3251 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3252 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3253 NULL, /* lv_adjust_loop_header_phi*/
3254 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3255 NULL /* flush_pending_stmts */