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,
4 2011, 2012 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 to
326 create a new empty basic block before HEAD. Both END and HEAD can be
327 NULL to 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. JUMP_LABEL is used only
1121 when redirecting to the EXIT_BLOCK, it is either ret_rtx or
1122 simple_return_rtx, indicating which kind of returnjump to create.
1123 It should be NULL otherwise. */
1126 force_nonfallthru_and_redirect (edge e, basic_block target, rtx jump_label)
1128 basic_block jump_block, new_bb = NULL, src = e->src;
1131 int abnormal_edge_flags = 0;
1132 bool asm_goto_edge = false;
1135 /* In the case the last instruction is conditional jump to the next
1136 instruction, first redirect the jump itself and then continue
1137 by creating a basic block afterwards to redirect fallthru edge. */
1138 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1139 && any_condjump_p (BB_END (e->src))
1140 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1143 edge b = unchecked_make_edge (e->src, target, 0);
1146 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1147 gcc_assert (redirected);
1149 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1152 int prob = INTVAL (XEXP (note, 0));
1154 b->probability = prob;
1155 b->count = e->count * prob / REG_BR_PROB_BASE;
1156 e->probability -= e->probability;
1157 e->count -= b->count;
1158 if (e->probability < 0)
1165 if (e->flags & EDGE_ABNORMAL)
1167 /* Irritating special case - fallthru edge to the same block as abnormal
1169 We can't redirect abnormal edge, but we still can split the fallthru
1170 one and create separate abnormal edge to original destination.
1171 This allows bb-reorder to make such edge non-fallthru. */
1172 gcc_assert (e->dest == target);
1173 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1174 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1178 gcc_assert (e->flags & EDGE_FALLTHRU);
1179 if (e->src == ENTRY_BLOCK_PTR)
1181 /* We can't redirect the entry block. Create an empty block
1182 at the start of the function which we use to add the new
1188 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1190 /* Change the existing edge's source to be the new block, and add
1191 a new edge from the entry block to the new block. */
1193 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1197 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1207 VEC_safe_push (edge, gc, bb->succs, e);
1208 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1212 /* If e->src ends with asm goto, see if any of the ASM_OPERANDS_LABELs
1213 don't point to target label. */
1214 if (JUMP_P (BB_END (e->src))
1215 && target != EXIT_BLOCK_PTR
1216 && e->dest == target
1217 && (e->flags & EDGE_FALLTHRU)
1218 && (note = extract_asm_operands (PATTERN (BB_END (e->src)))))
1220 int i, n = ASM_OPERANDS_LABEL_LENGTH (note);
1222 for (i = 0; i < n; ++i)
1223 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target))
1225 asm_goto_edge = true;
1230 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge)
1232 gcov_type count = e->count;
1233 int probability = e->probability;
1234 /* Create the new structures. */
1236 /* If the old block ended with a tablejump, skip its table
1237 by searching forward from there. Otherwise start searching
1238 forward from the last instruction of the old block. */
1239 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1240 note = BB_END (e->src);
1241 note = NEXT_INSN (note);
1243 jump_block = create_basic_block (note, NULL, e->src);
1244 jump_block->count = count;
1245 jump_block->frequency = EDGE_FREQUENCY (e);
1246 jump_block->loop_depth = target->loop_depth;
1248 /* Make sure new block ends up in correct hot/cold section. */
1250 BB_COPY_PARTITION (jump_block, e->src);
1251 if (flag_reorder_blocks_and_partition
1252 && targetm_common.have_named_sections
1253 && JUMP_P (BB_END (jump_block))
1254 && !any_condjump_p (BB_END (jump_block))
1255 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1256 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX);
1259 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1260 new_edge->probability = probability;
1261 new_edge->count = count;
1263 /* Redirect old edge. */
1264 redirect_edge_pred (e, jump_block);
1265 e->probability = REG_BR_PROB_BASE;
1267 /* If asm goto has any label refs to target's label,
1268 add also edge from asm goto bb to target. */
1271 new_edge->probability /= 2;
1272 new_edge->count /= 2;
1273 jump_block->count /= 2;
1274 jump_block->frequency /= 2;
1275 new_edge = make_edge (new_edge->src, target,
1276 e->flags & ~EDGE_FALLTHRU);
1277 new_edge->probability = probability - probability / 2;
1278 new_edge->count = count - count / 2;
1281 new_bb = jump_block;
1284 jump_block = e->src;
1286 if (e->goto_locus && e->goto_block == NULL)
1287 loc = e->goto_locus;
1290 e->flags &= ~EDGE_FALLTHRU;
1291 if (target == EXIT_BLOCK_PTR)
1293 if (jump_label == ret_rtx)
1296 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc);
1303 gcc_assert (jump_label == simple_return_rtx);
1304 #ifdef HAVE_simple_return
1305 emit_jump_insn_after_setloc (gen_simple_return (),
1306 BB_END (jump_block), loc);
1311 set_return_jump_label (BB_END (jump_block));
1315 rtx label = block_label (target);
1316 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc);
1317 JUMP_LABEL (BB_END (jump_block)) = label;
1318 LABEL_NUSES (label)++;
1321 emit_barrier_after (BB_END (jump_block));
1322 redirect_edge_succ_nodup (e, target);
1324 if (abnormal_edge_flags)
1325 make_edge (src, target, abnormal_edge_flags);
1327 df_mark_solutions_dirty ();
1331 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1332 (and possibly create new basic block) to make edge non-fallthru.
1333 Return newly created BB or NULL if none. */
1336 rtl_force_nonfallthru (edge e)
1338 return force_nonfallthru_and_redirect (e, e->dest, NULL_RTX);
1341 /* Redirect edge even at the expense of creating new jump insn or
1342 basic block. Return new basic block if created, NULL otherwise.
1343 Conversion must be possible. */
1346 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1348 if (redirect_edge_and_branch (e, target)
1349 || e->dest == target)
1352 /* In case the edge redirection failed, try to force it to be non-fallthru
1353 and redirect newly created simplejump. */
1354 df_set_bb_dirty (e->src);
1355 return force_nonfallthru_and_redirect (e, target, NULL_RTX);
1358 /* The given edge should potentially be a fallthru edge. If that is in
1359 fact true, delete the jump and barriers that are in the way. */
1362 rtl_tidy_fallthru_edge (edge e)
1365 basic_block b = e->src, c = b->next_bb;
1367 /* ??? In a late-running flow pass, other folks may have deleted basic
1368 blocks by nopping out blocks, leaving multiple BARRIERs between here
1369 and the target label. They ought to be chastised and fixed.
1371 We can also wind up with a sequence of undeletable labels between
1372 one block and the next.
1374 So search through a sequence of barriers, labels, and notes for
1375 the head of block C and assert that we really do fall through. */
1377 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1381 /* Remove what will soon cease being the jump insn from the source block.
1382 If block B consisted only of this single jump, turn it into a deleted
1387 && (any_uncondjump_p (q)
1388 || single_succ_p (b)))
1391 /* If this was a conditional jump, we need to also delete
1392 the insn that set cc0. */
1393 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1400 /* Selectively unlink the sequence. */
1401 if (q != PREV_INSN (BB_HEAD (c)))
1402 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false);
1404 e->flags |= EDGE_FALLTHRU;
1407 /* Should move basic block BB after basic block AFTER. NIY. */
1410 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1411 basic_block after ATTRIBUTE_UNUSED)
1416 /* Split a (typically critical) edge. Return the new block.
1417 The edge must not be abnormal.
1419 ??? The code generally expects to be called on critical edges.
1420 The case of a block ending in an unconditional jump to a
1421 block with multiple predecessors is not handled optimally. */
1424 rtl_split_edge (edge edge_in)
1429 /* Abnormal edges cannot be split. */
1430 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1432 /* We are going to place the new block in front of edge destination.
1433 Avoid existence of fallthru predecessors. */
1434 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1436 edge e = find_fallthru_edge (edge_in->dest->preds);
1439 force_nonfallthru (e);
1442 /* Create the basic block note. */
1443 if (edge_in->dest != EXIT_BLOCK_PTR)
1444 before = BB_HEAD (edge_in->dest);
1448 /* If this is a fall through edge to the exit block, the blocks might be
1449 not adjacent, and the right place is after the source. */
1450 if ((edge_in->flags & EDGE_FALLTHRU) && edge_in->dest == EXIT_BLOCK_PTR)
1452 before = NEXT_INSN (BB_END (edge_in->src));
1453 bb = create_basic_block (before, NULL, edge_in->src);
1454 BB_COPY_PARTITION (bb, edge_in->src);
1458 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1459 /* ??? Why not edge_in->dest->prev_bb here? */
1460 BB_COPY_PARTITION (bb, edge_in->dest);
1463 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1465 /* For non-fallthru edges, we must adjust the predecessor's
1466 jump instruction to target our new block. */
1467 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1469 edge redirected = redirect_edge_and_branch (edge_in, bb);
1470 gcc_assert (redirected);
1474 if (edge_in->src != ENTRY_BLOCK_PTR)
1476 /* For asm goto even splitting of fallthru edge might
1477 need insn patching, as other labels might point to the
1479 rtx last = BB_END (edge_in->src);
1482 && edge_in->dest != EXIT_BLOCK_PTR
1483 && extract_asm_operands (PATTERN (last)) != NULL_RTX
1484 && patch_jump_insn (last, before, bb))
1485 df_set_bb_dirty (edge_in->src);
1487 redirect_edge_succ (edge_in, bb);
1493 /* Queue instructions for insertion on an edge between two basic blocks.
1494 The new instructions and basic blocks (if any) will not appear in the
1495 CFG until commit_edge_insertions is called. */
1498 insert_insn_on_edge (rtx pattern, edge e)
1500 /* We cannot insert instructions on an abnormal critical edge.
1501 It will be easier to find the culprit if we die now. */
1502 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1504 if (e->insns.r == NULL_RTX)
1507 push_to_sequence (e->insns.r);
1509 emit_insn (pattern);
1511 e->insns.r = get_insns ();
1515 /* Update the CFG for the instructions queued on edge E. */
1518 commit_one_edge_insertion (edge e)
1520 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1523 /* Pull the insns off the edge now since the edge might go away. */
1525 e->insns.r = NULL_RTX;
1527 /* Figure out where to put these insns. If the destination has
1528 one predecessor, insert there. Except for the exit block. */
1529 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1533 /* Get the location correct wrt a code label, and "nice" wrt
1534 a basic block note, and before everything else. */
1537 tmp = NEXT_INSN (tmp);
1538 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1539 tmp = NEXT_INSN (tmp);
1540 if (tmp == BB_HEAD (bb))
1543 after = PREV_INSN (tmp);
1545 after = get_last_insn ();
1548 /* If the source has one successor and the edge is not abnormal,
1549 insert there. Except for the entry block. */
1550 else if ((e->flags & EDGE_ABNORMAL) == 0
1551 && single_succ_p (e->src)
1552 && e->src != ENTRY_BLOCK_PTR)
1556 /* It is possible to have a non-simple jump here. Consider a target
1557 where some forms of unconditional jumps clobber a register. This
1558 happens on the fr30 for example.
1560 We know this block has a single successor, so we can just emit
1561 the queued insns before the jump. */
1562 if (JUMP_P (BB_END (bb)))
1563 before = BB_END (bb);
1566 /* We'd better be fallthru, or we've lost track of what's what. */
1567 gcc_assert (e->flags & EDGE_FALLTHRU);
1569 after = BB_END (bb);
1573 /* Otherwise we must split the edge. */
1576 bb = split_edge (e);
1577 after = BB_END (bb);
1579 if (flag_reorder_blocks_and_partition
1580 && targetm_common.have_named_sections
1581 && e->src != ENTRY_BLOCK_PTR
1582 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1583 && !(e->flags & EDGE_CROSSING)
1585 && !any_condjump_p (after)
1586 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1587 add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX);
1590 /* Now that we've found the spot, do the insertion. */
1593 emit_insn_before_noloc (insns, before, bb);
1594 last = prev_nonnote_insn (before);
1597 last = emit_insn_after_noloc (insns, after, bb);
1599 if (returnjump_p (last))
1601 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1602 This is not currently a problem because this only happens
1603 for the (single) epilogue, which already has a fallthru edge
1606 e = single_succ_edge (bb);
1607 gcc_assert (e->dest == EXIT_BLOCK_PTR
1608 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1610 e->flags &= ~EDGE_FALLTHRU;
1611 emit_barrier_after (last);
1614 delete_insn (before);
1617 gcc_assert (!JUMP_P (last));
1620 /* Update the CFG for all queued instructions. */
1623 commit_edge_insertions (void)
1627 #ifdef ENABLE_CHECKING
1628 verify_flow_info ();
1631 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1636 FOR_EACH_EDGE (e, ei, bb->succs)
1638 commit_one_edge_insertion (e);
1643 /* Print out RTL-specific basic block information (live information
1644 at start and end). */
1647 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED)
1653 s_indent = (char *) alloca ((size_t) indent + 1);
1654 memset (s_indent, ' ', (size_t) indent);
1655 s_indent[indent] = '\0';
1659 df_dump_top (bb, outf);
1663 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1664 insn = NEXT_INSN (insn))
1665 print_rtl_single (outf, insn);
1669 df_dump_bottom (bb, outf);
1675 /* Like print_rtl, but also print out live information for the start of each
1679 print_rtl_with_bb (FILE *outf, const_rtx rtx_first)
1683 fprintf (outf, "(nil)\n");
1686 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1687 int max_uid = get_max_uid ();
1688 basic_block *start = XCNEWVEC (basic_block, max_uid);
1689 basic_block *end = XCNEWVEC (basic_block, max_uid);
1690 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1695 df_dump_start (outf);
1697 FOR_EACH_BB_REVERSE (bb)
1701 start[INSN_UID (BB_HEAD (bb))] = bb;
1702 end[INSN_UID (BB_END (bb))] = bb;
1703 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1705 enum bb_state state = IN_MULTIPLE_BB;
1707 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1709 in_bb_p[INSN_UID (x)] = state;
1711 if (x == BB_END (bb))
1716 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1720 bb = start[INSN_UID (tmp_rtx)];
1722 dump_bb_info (bb, true, false, dump_flags, ";; ", outf);
1724 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1725 && !NOTE_P (tmp_rtx)
1726 && !BARRIER_P (tmp_rtx))
1727 fprintf (outf, ";; Insn is not within a basic block\n");
1728 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1729 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1731 did_output = print_rtl_single (outf, tmp_rtx);
1733 bb = end[INSN_UID (tmp_rtx)];
1735 dump_bb_info (bb, false, true, dump_flags, ";; ", outf);
1745 if (crtl->epilogue_delay_list != 0)
1747 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1748 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0;
1749 tmp_rtx = XEXP (tmp_rtx, 1))
1750 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1755 update_br_prob_note (basic_block bb)
1758 if (!JUMP_P (BB_END (bb)))
1760 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1761 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1763 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1766 /* Get the last insn associated with block BB (that includes barriers and
1767 tablejumps after BB). */
1769 get_last_bb_insn (basic_block bb)
1772 rtx end = BB_END (bb);
1774 /* Include any jump table following the basic block. */
1775 if (tablejump_p (end, NULL, &tmp))
1778 /* Include any barriers that may follow the basic block. */
1779 tmp = next_nonnote_insn_bb (end);
1780 while (tmp && BARRIER_P (tmp))
1783 tmp = next_nonnote_insn_bb (end);
1789 /* Verify the CFG and RTL consistency common for both underlying RTL and
1792 Currently it does following checks:
1794 - overlapping of basic blocks
1795 - insns with wrong BLOCK_FOR_INSN pointers
1796 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1797 - tails of basic blocks (ensure that boundary is necessary)
1798 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1799 and NOTE_INSN_BASIC_BLOCK
1800 - verify that no fall_thru edge crosses hot/cold partition boundaries
1801 - verify that there are no pending RTL branch predictions
1803 In future it can be extended check a lot of other stuff as well
1804 (reachability of basic blocks, life information, etc. etc.). */
1807 rtl_verify_flow_info_1 (void)
1813 /* Check the general integrity of the basic blocks. */
1814 FOR_EACH_BB_REVERSE (bb)
1818 if (!(bb->flags & BB_RTL))
1820 error ("BB_RTL flag not set for block %d", bb->index);
1824 FOR_BB_INSNS (bb, insn)
1825 if (BLOCK_FOR_INSN (insn) != bb)
1827 error ("insn %d basic block pointer is %d, should be %d",
1829 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1834 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1835 if (!BARRIER_P (insn)
1836 && BLOCK_FOR_INSN (insn) != NULL)
1838 error ("insn %d in header of bb %d has non-NULL basic block",
1839 INSN_UID (insn), bb->index);
1842 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1843 if (!BARRIER_P (insn)
1844 && BLOCK_FOR_INSN (insn) != NULL)
1846 error ("insn %d in footer of bb %d has non-NULL basic block",
1847 INSN_UID (insn), bb->index);
1852 /* Now check the basic blocks (boundaries etc.) */
1853 FOR_EACH_BB_REVERSE (bb)
1855 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1856 edge e, fallthru = NULL;
1860 if (JUMP_P (BB_END (bb))
1861 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1862 && EDGE_COUNT (bb->succs) >= 2
1863 && any_condjump_p (BB_END (bb)))
1865 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1866 && profile_status != PROFILE_ABSENT)
1868 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1869 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1873 FOR_EACH_EDGE (e, ei, bb->succs)
1877 if (e->flags & EDGE_FALLTHRU)
1878 n_fallthru++, fallthru = e;
1880 is_crossing = (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1881 && e->src != ENTRY_BLOCK_PTR
1882 && e->dest != EXIT_BLOCK_PTR);
1883 if (e->flags & EDGE_CROSSING)
1887 error ("EDGE_CROSSING incorrectly set across same section");
1890 if (e->flags & EDGE_FALLTHRU)
1892 error ("fallthru edge crosses section boundary (bb %i)",
1896 if (e->flags & EDGE_EH)
1898 error ("EH edge crosses section boundary (bb %i)",
1903 else if (is_crossing)
1905 error ("EDGE_CROSSING missing across section boundary");
1909 if ((e->flags & ~(EDGE_DFS_BACK
1911 | EDGE_IRREDUCIBLE_LOOP
1914 | EDGE_PRESERVE)) == 0)
1917 if (e->flags & EDGE_ABNORMAL_CALL)
1920 if (e->flags & EDGE_EH)
1922 else if (e->flags & EDGE_ABNORMAL)
1926 if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1928 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1933 error ("too many eh edges %i", bb->index);
1937 && (!JUMP_P (BB_END (bb))
1938 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1939 || any_condjump_p (BB_END (bb))))))
1941 error ("too many outgoing branch edges from bb %i", bb->index);
1944 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1946 error ("fallthru edge after unconditional jump %i", bb->index);
1949 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1951 error ("wrong number of branch edges after unconditional jump %i",
1955 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1956 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1958 error ("wrong amount of branch edges after conditional jump %i",
1962 if (n_call && !CALL_P (BB_END (bb)))
1964 error ("call edges for non-call insn in bb %i", bb->index);
1968 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1969 && (!JUMP_P (BB_END (bb))
1970 || any_condjump_p (BB_END (bb))
1971 || any_uncondjump_p (BB_END (bb))))
1973 error ("abnormal edges for no purpose in bb %i", bb->index);
1977 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1978 /* We may have a barrier inside a basic block before dead code
1979 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1980 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1983 if (! BLOCK_FOR_INSN (x))
1985 ("insn %d inside basic block %d but block_for_insn is NULL",
1986 INSN_UID (x), bb->index);
1989 ("insn %d inside basic block %d but block_for_insn is %i",
1990 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1995 /* OK pointers are correct. Now check the header of basic
1996 block. It ought to contain optional CODE_LABEL followed
1997 by NOTE_BASIC_BLOCK. */
2001 if (BB_END (bb) == x)
2003 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2011 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2013 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2018 if (BB_END (bb) == x)
2019 /* Do checks for empty blocks here. */
2022 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2024 if (NOTE_INSN_BASIC_BLOCK_P (x))
2026 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2027 INSN_UID (x), bb->index);
2031 if (x == BB_END (bb))
2034 if (control_flow_insn_p (x))
2036 error ("in basic block %d:", bb->index);
2037 fatal_insn ("flow control insn inside a basic block", x);
2046 /* Verify the CFG and RTL consistency common for both underlying RTL and
2049 Currently it does following checks:
2050 - all checks of rtl_verify_flow_info_1
2051 - test head/end pointers
2052 - check that all insns are in the basic blocks
2053 (except the switch handling code, barriers and notes)
2054 - check that all returns are followed by barriers
2055 - check that all fallthru edge points to the adjacent blocks. */
2058 rtl_verify_flow_info (void)
2061 int err = rtl_verify_flow_info_1 ();
2063 rtx last_head = get_last_insn ();
2064 basic_block *bb_info;
2066 const rtx rtx_first = get_insns ();
2067 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2068 const int max_uid = get_max_uid ();
2070 bb_info = XCNEWVEC (basic_block, max_uid);
2072 FOR_EACH_BB_REVERSE (bb)
2075 rtx head = BB_HEAD (bb);
2076 rtx end = BB_END (bb);
2078 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2080 /* Verify the end of the basic block is in the INSN chain. */
2084 /* And that the code outside of basic blocks has NULL bb field. */
2086 && BLOCK_FOR_INSN (x) != NULL)
2088 error ("insn %d outside of basic blocks has non-NULL bb field",
2096 error ("end insn %d for block %d not found in the insn stream",
2097 INSN_UID (end), bb->index);
2101 /* Work backwards from the end to the head of the basic block
2102 to verify the head is in the RTL chain. */
2103 for (; x != NULL_RTX; x = PREV_INSN (x))
2105 /* While walking over the insn chain, verify insns appear
2106 in only one basic block. */
2107 if (bb_info[INSN_UID (x)] != NULL)
2109 error ("insn %d is in multiple basic blocks (%d and %d)",
2110 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
2114 bb_info[INSN_UID (x)] = bb;
2121 error ("head insn %d for block %d not found in the insn stream",
2122 INSN_UID (head), bb->index);
2126 last_head = PREV_INSN (x);
2128 e = find_fallthru_edge (bb->succs);
2133 /* Ensure existence of barrier in BB with no fallthru edges. */
2134 for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn))
2136 if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn))
2138 error ("missing barrier after block %i", bb->index);
2142 if (BARRIER_P (insn))
2146 else if (e->src != ENTRY_BLOCK_PTR
2147 && e->dest != EXIT_BLOCK_PTR)
2151 if (e->src->next_bb != e->dest)
2154 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2155 e->src->index, e->dest->index);
2159 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2160 insn = NEXT_INSN (insn))
2161 if (BARRIER_P (insn) || INSN_P (insn))
2163 error ("verify_flow_info: Incorrect fallthru %i->%i",
2164 e->src->index, e->dest->index);
2165 fatal_insn ("wrong insn in the fallthru edge", insn);
2171 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2173 /* Check that the code before the first basic block has NULL
2176 && BLOCK_FOR_INSN (x) != NULL)
2178 error ("insn %d outside of basic blocks has non-NULL bb field",
2186 last_bb_seen = ENTRY_BLOCK_PTR;
2188 for (x = rtx_first; x; x = NEXT_INSN (x))
2190 if (NOTE_INSN_BASIC_BLOCK_P (x))
2192 bb = NOTE_BASIC_BLOCK (x);
2195 if (bb != last_bb_seen->next_bb)
2196 internal_error ("basic blocks not laid down consecutively");
2198 curr_bb = last_bb_seen = bb;
2203 switch (GET_CODE (x))
2210 /* An addr_vec is placed outside any basic block. */
2212 && JUMP_TABLE_DATA_P (NEXT_INSN (x)))
2215 /* But in any case, non-deletable labels can appear anywhere. */
2219 fatal_insn ("insn outside basic block", x);
2224 && returnjump_p (x) && ! condjump_p (x)
2225 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2226 fatal_insn ("return not followed by barrier", x);
2227 if (curr_bb && x == BB_END (curr_bb))
2231 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2233 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2234 num_bb_notes, n_basic_blocks);
2239 /* Assume that the preceding pass has possibly eliminated jump instructions
2240 or converted the unconditional jumps. Eliminate the edges from CFG.
2241 Return true if any edges are eliminated. */
2244 purge_dead_edges (basic_block bb)
2247 rtx insn = BB_END (bb), note;
2248 bool purged = false;
2252 if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb))
2254 insn = PREV_INSN (insn);
2255 while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb));
2257 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2258 if (NONJUMP_INSN_P (insn)
2259 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2263 if (! may_trap_p (PATTERN (insn))
2264 || ((eqnote = find_reg_equal_equiv_note (insn))
2265 && ! may_trap_p (XEXP (eqnote, 0))))
2266 remove_note (insn, note);
2269 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2270 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2272 bool remove = false;
2274 /* There are three types of edges we need to handle correctly here: EH
2275 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2276 latter can appear when nonlocal gotos are used. */
2277 if (e->flags & EDGE_ABNORMAL_CALL)
2281 else if (can_nonlocal_goto (insn))
2283 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2285 else if (flag_tm && find_reg_note (insn, REG_TM, NULL))
2290 else if (e->flags & EDGE_EH)
2291 remove = !can_throw_internal (insn);
2296 df_set_bb_dirty (bb);
2309 /* We do care only about conditional jumps and simplejumps. */
2310 if (!any_condjump_p (insn)
2311 && !returnjump_p (insn)
2312 && !simplejump_p (insn))
2315 /* Branch probability/prediction notes are defined only for
2316 condjumps. We've possibly turned condjump into simplejump. */
2317 if (simplejump_p (insn))
2319 note = find_reg_note (insn, REG_BR_PROB, NULL);
2321 remove_note (insn, note);
2322 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2323 remove_note (insn, note);
2326 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2328 /* Avoid abnormal flags to leak from computed jumps turned
2329 into simplejumps. */
2331 e->flags &= ~EDGE_ABNORMAL;
2333 /* See if this edge is one we should keep. */
2334 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2335 /* A conditional jump can fall through into the next
2336 block, so we should keep the edge. */
2341 else if (e->dest != EXIT_BLOCK_PTR
2342 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2343 /* If the destination block is the target of the jump,
2349 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2350 /* If the destination block is the exit block, and this
2351 instruction is a return, then keep the edge. */
2356 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2357 /* Keep the edges that correspond to exceptions thrown by
2358 this instruction and rematerialize the EDGE_ABNORMAL
2359 flag we just cleared above. */
2361 e->flags |= EDGE_ABNORMAL;
2366 /* We do not need this edge. */
2367 df_set_bb_dirty (bb);
2372 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2376 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2381 /* Redistribute probabilities. */
2382 if (single_succ_p (bb))
2384 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2385 single_succ_edge (bb)->count = bb->count;
2389 note = find_reg_note (insn, REG_BR_PROB, NULL);
2393 b = BRANCH_EDGE (bb);
2394 f = FALLTHRU_EDGE (bb);
2395 b->probability = INTVAL (XEXP (note, 0));
2396 f->probability = REG_BR_PROB_BASE - b->probability;
2397 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2398 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2403 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2405 /* First, there should not be any EH or ABCALL edges resulting
2406 from non-local gotos and the like. If there were, we shouldn't
2407 have created the sibcall in the first place. Second, there
2408 should of course never have been a fallthru edge. */
2409 gcc_assert (single_succ_p (bb));
2410 gcc_assert (single_succ_edge (bb)->flags
2411 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2416 /* If we don't see a jump insn, we don't know exactly why the block would
2417 have been broken at this point. Look for a simple, non-fallthru edge,
2418 as these are only created by conditional branches. If we find such an
2419 edge we know that there used to be a jump here and can then safely
2420 remove all non-fallthru edges. */
2422 FOR_EACH_EDGE (e, ei, bb->succs)
2423 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2432 /* Remove all but the fake and fallthru edges. The fake edge may be
2433 the only successor for this block in the case of noreturn
2435 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2437 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2439 df_set_bb_dirty (bb);
2447 gcc_assert (single_succ_p (bb));
2449 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2450 single_succ_edge (bb)->count = bb->count;
2453 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2458 /* Search all basic blocks for potentially dead edges and purge them. Return
2459 true if some edge has been eliminated. */
2462 purge_all_dead_edges (void)
2469 bool purged_here = purge_dead_edges (bb);
2471 purged |= purged_here;
2477 /* This is used by a few passes that emit some instructions after abnormal
2478 calls, moving the basic block's end, while they in fact do want to emit
2479 them on the fallthru edge. Look for abnormal call edges, find backward
2480 the call in the block and insert the instructions on the edge instead.
2482 Similarly, handle instructions throwing exceptions internally.
2484 Return true when instructions have been found and inserted on edges. */
2487 fixup_abnormal_edges (void)
2489 bool inserted = false;
2497 /* Look for cases we are interested in - calls or instructions causing
2499 FOR_EACH_EDGE (e, ei, bb->succs)
2500 if ((e->flags & EDGE_ABNORMAL_CALL)
2501 || ((e->flags & (EDGE_ABNORMAL | EDGE_EH))
2502 == (EDGE_ABNORMAL | EDGE_EH)))
2505 if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb)))
2509 /* Get past the new insns generated. Allow notes, as the insns
2510 may be already deleted. */
2512 while ((NONJUMP_INSN_P (insn) || NOTE_P (insn))
2513 && !can_throw_internal (insn)
2514 && insn != BB_HEAD (bb))
2515 insn = PREV_INSN (insn);
2517 if (CALL_P (insn) || can_throw_internal (insn))
2521 e = find_fallthru_edge (bb->succs);
2523 stop = NEXT_INSN (BB_END (bb));
2526 for (insn = NEXT_INSN (insn); insn != stop; insn = next)
2528 next = NEXT_INSN (insn);
2533 /* Sometimes there's still the return value USE.
2534 If it's placed after a trapping call (i.e. that
2535 call is the last insn anyway), we have no fallthru
2536 edge. Simply delete this use and don't try to insert
2537 on the non-existent edge. */
2538 if (GET_CODE (PATTERN (insn)) != USE)
2540 /* We're not deleting it, we're moving it. */
2541 INSN_DELETED_P (insn) = 0;
2542 PREV_INSN (insn) = NULL_RTX;
2543 NEXT_INSN (insn) = NULL_RTX;
2545 insert_insn_on_edge (insn, e);
2549 else if (!BARRIER_P (insn))
2550 set_block_for_insn (insn, NULL);
2554 /* It may be that we don't find any trapping insn. In this
2555 case we discovered quite late that the insn that had been
2556 marked as can_throw_internal in fact couldn't trap at all.
2557 So we should in fact delete the EH edges out of the block. */
2559 purge_dead_edges (bb);
2566 /* Same as split_block but update cfg_layout structures. */
2569 cfg_layout_split_block (basic_block bb, void *insnp)
2571 rtx insn = (rtx) insnp;
2572 basic_block new_bb = rtl_split_block (bb, insn);
2574 new_bb->il.rtl->footer = bb->il.rtl->footer;
2575 bb->il.rtl->footer = NULL;
2580 /* Redirect Edge to DEST. */
2582 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2584 basic_block src = e->src;
2587 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2590 if (e->dest == dest)
2593 if (e->src != ENTRY_BLOCK_PTR
2594 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2596 df_set_bb_dirty (src);
2600 if (e->src == ENTRY_BLOCK_PTR
2601 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2604 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2605 e->src->index, dest->index);
2607 df_set_bb_dirty (e->src);
2608 redirect_edge_succ (e, dest);
2612 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2613 in the case the basic block appears to be in sequence. Avoid this
2616 if (e->flags & EDGE_FALLTHRU)
2618 /* Redirect any branch edges unified with the fallthru one. */
2619 if (JUMP_P (BB_END (src))
2620 && label_is_jump_target_p (BB_HEAD (e->dest),
2626 fprintf (dump_file, "Fallthru edge unified with branch "
2627 "%i->%i redirected to %i\n",
2628 e->src->index, e->dest->index, dest->index);
2629 e->flags &= ~EDGE_FALLTHRU;
2630 redirected = redirect_branch_edge (e, dest);
2631 gcc_assert (redirected);
2632 redirected->flags |= EDGE_FALLTHRU;
2633 df_set_bb_dirty (redirected->src);
2636 /* In case we are redirecting fallthru edge to the branch edge
2637 of conditional jump, remove it. */
2638 if (EDGE_COUNT (src->succs) == 2)
2640 /* Find the edge that is different from E. */
2641 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2644 && any_condjump_p (BB_END (src))
2645 && onlyjump_p (BB_END (src)))
2646 delete_insn (BB_END (src));
2649 fprintf (dump_file, "Redirecting fallthru edge %i->%i to %i\n",
2650 e->src->index, e->dest->index, dest->index);
2651 ret = redirect_edge_succ_nodup (e, dest);
2654 ret = redirect_branch_edge (e, dest);
2656 /* We don't want simplejumps in the insn stream during cfglayout. */
2657 gcc_assert (!simplejump_p (BB_END (src)));
2659 df_set_bb_dirty (src);
2663 /* Simple wrapper as we always can redirect fallthru edges. */
2665 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2667 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2669 gcc_assert (redirected);
2673 /* Same as delete_basic_block but update cfg_layout structures. */
2676 cfg_layout_delete_block (basic_block bb)
2678 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2680 if (bb->il.rtl->header)
2682 next = BB_HEAD (bb);
2684 NEXT_INSN (prev) = bb->il.rtl->header;
2686 set_first_insn (bb->il.rtl->header);
2687 PREV_INSN (bb->il.rtl->header) = prev;
2688 insn = bb->il.rtl->header;
2689 while (NEXT_INSN (insn))
2690 insn = NEXT_INSN (insn);
2691 NEXT_INSN (insn) = next;
2692 PREV_INSN (next) = insn;
2694 next = NEXT_INSN (BB_END (bb));
2695 if (bb->il.rtl->footer)
2697 insn = bb->il.rtl->footer;
2700 if (BARRIER_P (insn))
2702 if (PREV_INSN (insn))
2703 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2705 bb->il.rtl->footer = NEXT_INSN (insn);
2706 if (NEXT_INSN (insn))
2707 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2711 insn = NEXT_INSN (insn);
2713 if (bb->il.rtl->footer)
2716 NEXT_INSN (insn) = bb->il.rtl->footer;
2717 PREV_INSN (bb->il.rtl->footer) = insn;
2718 while (NEXT_INSN (insn))
2719 insn = NEXT_INSN (insn);
2720 NEXT_INSN (insn) = next;
2722 PREV_INSN (next) = insn;
2724 set_last_insn (insn);
2727 if (bb->next_bb != EXIT_BLOCK_PTR)
2728 to = &bb->next_bb->il.rtl->header;
2730 to = &cfg_layout_function_footer;
2732 rtl_delete_block (bb);
2735 prev = NEXT_INSN (prev);
2737 prev = get_insns ();
2739 next = PREV_INSN (next);
2741 next = get_last_insn ();
2743 if (next && NEXT_INSN (next) != prev)
2745 remaints = unlink_insn_chain (prev, next);
2747 while (NEXT_INSN (insn))
2748 insn = NEXT_INSN (insn);
2749 NEXT_INSN (insn) = *to;
2751 PREV_INSN (*to) = insn;
2756 /* Return true when blocks A and B can be safely merged. */
2759 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2761 /* If we are partitioning hot/cold basic blocks, we don't want to
2762 mess up unconditional or indirect jumps that cross between hot
2765 Basic block partitioning may result in some jumps that appear to
2766 be optimizable (or blocks that appear to be mergeable), but which really
2767 must be left untouched (they are required to make it safely across
2768 partition boundaries). See the comments at the top of
2769 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2771 if (BB_PARTITION (a) != BB_PARTITION (b))
2774 /* If we would end up moving B's instructions, make sure it doesn't fall
2775 through into the exit block, since we cannot recover from a fallthrough
2776 edge into the exit block occurring in the middle of a function. */
2777 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2779 edge e = find_fallthru_edge (b->succs);
2780 if (e && e->dest == EXIT_BLOCK_PTR)
2784 /* There must be exactly one edge in between the blocks. */
2785 return (single_succ_p (a)
2786 && single_succ (a) == b
2787 && single_pred_p (b) == 1
2789 /* Must be simple edge. */
2790 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2791 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2792 /* If the jump insn has side effects, we can't kill the edge.
2793 When not optimizing, try_redirect_by_replacing_jump will
2794 not allow us to redirect an edge by replacing a table jump. */
2795 && (!JUMP_P (BB_END (a))
2796 || ((!optimize || reload_completed)
2797 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2800 /* Merge block A and B. The blocks must be mergeable. */
2803 cfg_layout_merge_blocks (basic_block a, basic_block b)
2805 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
2807 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b));
2810 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
2813 /* If there was a CODE_LABEL beginning B, delete it. */
2814 if (LABEL_P (BB_HEAD (b)))
2816 delete_insn (BB_HEAD (b));
2819 /* We should have fallthru edge in a, or we can do dummy redirection to get
2821 if (JUMP_P (BB_END (a)))
2822 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2823 gcc_assert (!JUMP_P (BB_END (a)));
2825 /* When not optimizing and the edge is the only place in RTL which holds
2826 some unique locus, emit a nop with that locus in between. */
2827 if (!optimize && EDGE_SUCC (a, 0)->goto_locus)
2829 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a));
2830 int goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2832 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
2833 insn = PREV_INSN (insn);
2834 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus))
2839 end = NEXT_INSN (BB_END (b));
2840 while (insn != end && !INSN_P (insn))
2841 insn = NEXT_INSN (insn);
2842 if (insn != end && INSN_LOCATOR (insn) != 0
2843 && locator_eq (INSN_LOCATOR (insn), goto_locus))
2848 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a);
2849 INSN_LOCATOR (BB_END (a)) = goto_locus;
2853 /* Possible line number notes should appear in between. */
2854 if (b->il.rtl->header)
2856 rtx first = BB_END (a), last;
2858 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2859 delete_insn_chain (NEXT_INSN (first), last, false);
2860 b->il.rtl->header = NULL;
2863 /* In the case basic blocks are not adjacent, move them around. */
2864 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2866 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2868 emit_insn_after_noloc (first, BB_END (a), a);
2869 /* Skip possible DELETED_LABEL insn. */
2870 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2871 first = NEXT_INSN (first);
2872 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2875 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
2876 We need to explicitly call. */
2877 update_bb_for_insn_chain (NEXT_INSN (first),
2881 delete_insn (first);
2883 /* Otherwise just re-associate the instructions. */
2888 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a);
2891 /* Skip possible DELETED_LABEL insn. */
2892 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2893 insn = NEXT_INSN (insn);
2894 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2896 BB_END (a) = BB_END (b);
2900 df_bb_delete (b->index);
2902 /* Possible tablejumps and barriers should appear after the block. */
2903 if (b->il.rtl->footer)
2905 if (!a->il.rtl->footer)
2906 a->il.rtl->footer = b->il.rtl->footer;
2909 rtx last = a->il.rtl->footer;
2911 while (NEXT_INSN (last))
2912 last = NEXT_INSN (last);
2913 NEXT_INSN (last) = b->il.rtl->footer;
2914 PREV_INSN (b->il.rtl->footer) = last;
2916 b->il.rtl->footer = NULL;
2919 /* If B was a forwarder block, propagate the locus on the edge. */
2920 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
2921 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2924 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
2930 cfg_layout_split_edge (edge e)
2932 basic_block new_bb =
2933 create_basic_block (e->src != ENTRY_BLOCK_PTR
2934 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2937 if (e->dest == EXIT_BLOCK_PTR)
2938 BB_COPY_PARTITION (new_bb, e->src);
2940 BB_COPY_PARTITION (new_bb, e->dest);
2941 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2942 redirect_edge_and_branch_force (e, new_bb);
2947 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2950 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2954 /* Return 1 if BB ends with a call, possibly followed by some
2955 instructions that must stay with the call, 0 otherwise. */
2958 rtl_block_ends_with_call_p (basic_block bb)
2960 rtx insn = BB_END (bb);
2962 while (!CALL_P (insn)
2963 && insn != BB_HEAD (bb)
2964 && (keep_with_call_p (insn)
2966 || DEBUG_INSN_P (insn)))
2967 insn = PREV_INSN (insn);
2968 return (CALL_P (insn));
2971 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2974 rtl_block_ends_with_condjump_p (const_basic_block bb)
2976 return any_condjump_p (BB_END (bb));
2979 /* Return true if we need to add fake edge to exit.
2980 Helper function for rtl_flow_call_edges_add. */
2983 need_fake_edge_p (const_rtx insn)
2989 && !SIBLING_CALL_P (insn)
2990 && !find_reg_note (insn, REG_NORETURN, NULL)
2991 && !(RTL_CONST_OR_PURE_CALL_P (insn))))
2994 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2995 && MEM_VOLATILE_P (PATTERN (insn)))
2996 || (GET_CODE (PATTERN (insn)) == PARALLEL
2997 && asm_noperands (insn) != -1
2998 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2999 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
3002 /* Add fake edges to the function exit for any non constant and non noreturn
3003 calls, volatile inline assembly in the bitmap of blocks specified by
3004 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
3007 The goal is to expose cases in which entering a basic block does not imply
3008 that all subsequent instructions must be executed. */
3011 rtl_flow_call_edges_add (sbitmap blocks)
3014 int blocks_split = 0;
3015 int last_bb = last_basic_block;
3016 bool check_last_block = false;
3018 if (n_basic_blocks == NUM_FIXED_BLOCKS)
3022 check_last_block = true;
3024 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
3026 /* In the last basic block, before epilogue generation, there will be
3027 a fallthru edge to EXIT. Special care is required if the last insn
3028 of the last basic block is a call because make_edge folds duplicate
3029 edges, which would result in the fallthru edge also being marked
3030 fake, which would result in the fallthru edge being removed by
3031 remove_fake_edges, which would result in an invalid CFG.
3033 Moreover, we can't elide the outgoing fake edge, since the block
3034 profiler needs to take this into account in order to solve the minimal
3035 spanning tree in the case that the call doesn't return.
3037 Handle this by adding a dummy instruction in a new last basic block. */
3038 if (check_last_block)
3040 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
3041 rtx insn = BB_END (bb);
3043 /* Back up past insns that must be kept in the same block as a call. */
3044 while (insn != BB_HEAD (bb)
3045 && keep_with_call_p (insn))
3046 insn = PREV_INSN (insn);
3048 if (need_fake_edge_p (insn))
3052 e = find_edge (bb, EXIT_BLOCK_PTR);
3055 insert_insn_on_edge (gen_use (const0_rtx), e);
3056 commit_edge_insertions ();
3061 /* Now add fake edges to the function exit for any non constant
3062 calls since there is no way that we can determine if they will
3065 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
3067 basic_block bb = BASIC_BLOCK (i);
3074 if (blocks && !TEST_BIT (blocks, i))
3077 for (insn = BB_END (bb); ; insn = prev_insn)
3079 prev_insn = PREV_INSN (insn);
3080 if (need_fake_edge_p (insn))
3083 rtx split_at_insn = insn;
3085 /* Don't split the block between a call and an insn that should
3086 remain in the same block as the call. */
3088 while (split_at_insn != BB_END (bb)
3089 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3090 split_at_insn = NEXT_INSN (split_at_insn);
3092 /* The handling above of the final block before the epilogue
3093 should be enough to verify that there is no edge to the exit
3094 block in CFG already. Calling make_edge in such case would
3095 cause us to mark that edge as fake and remove it later. */
3097 #ifdef ENABLE_CHECKING
3098 if (split_at_insn == BB_END (bb))
3100 e = find_edge (bb, EXIT_BLOCK_PTR);
3101 gcc_assert (e == NULL);
3105 /* Note that the following may create a new basic block
3106 and renumber the existing basic blocks. */
3107 if (split_at_insn != BB_END (bb))
3109 e = split_block (bb, split_at_insn);
3114 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3117 if (insn == BB_HEAD (bb))
3123 verify_flow_info ();
3125 return blocks_split;
3128 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
3129 the conditional branch target, SECOND_HEAD should be the fall-thru
3130 there is no need to handle this here the loop versioning code handles
3131 this. the reason for SECON_HEAD is that it is needed for condition
3132 in trees, and this should be of the same type since it is a hook. */
3134 rtl_lv_add_condition_to_bb (basic_block first_head ,
3135 basic_block second_head ATTRIBUTE_UNUSED,
3136 basic_block cond_bb, void *comp_rtx)
3138 rtx label, seq, jump;
3139 rtx op0 = XEXP ((rtx)comp_rtx, 0);
3140 rtx op1 = XEXP ((rtx)comp_rtx, 1);
3141 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
3142 enum machine_mode mode;
3145 label = block_label (first_head);
3146 mode = GET_MODE (op0);
3147 if (mode == VOIDmode)
3148 mode = GET_MODE (op1);
3151 op0 = force_operand (op0, NULL_RTX);
3152 op1 = force_operand (op1, NULL_RTX);
3153 do_compare_rtx_and_jump (op0, op1, comp, 0,
3154 mode, NULL_RTX, NULL_RTX, label, -1);
3155 jump = get_last_insn ();
3156 JUMP_LABEL (jump) = label;
3157 LABEL_NUSES (label)++;
3161 /* Add the new cond , in the new head. */
3162 emit_insn_after(seq, BB_END(cond_bb));
3166 /* Given a block B with unconditional branch at its end, get the
3167 store the return the branch edge and the fall-thru edge in
3168 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
3170 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
3171 edge *fallthru_edge)
3173 edge e = EDGE_SUCC (b, 0);
3175 if (e->flags & EDGE_FALLTHRU)
3178 *branch_edge = EDGE_SUCC (b, 1);
3183 *fallthru_edge = EDGE_SUCC (b, 1);
3188 init_rtl_bb_info (basic_block bb)
3190 gcc_assert (!bb->il.rtl);
3191 bb->il.rtl = ggc_alloc_cleared_rtl_bb_info ();
3194 /* Returns true if it is possible to remove edge E by redirecting
3195 it to the destination of the other edge from E->src. */
3198 rtl_can_remove_branch_p (const_edge e)
3200 const_basic_block src = e->src;
3201 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3202 const_rtx insn = BB_END (src), set;
3204 /* The conditions are taken from try_redirect_by_replacing_jump. */
3205 if (target == EXIT_BLOCK_PTR)
3208 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3211 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3212 || BB_PARTITION (src) != BB_PARTITION (target))
3215 if (!onlyjump_p (insn)
3216 || tablejump_p (insn, NULL, NULL))
3219 set = single_set (insn);
3220 if (!set || side_effects_p (set))
3226 /* We do not want to declare these functions in a header file, since they
3227 should only be used through the cfghooks interface, and we do not want to
3228 move them here since it would require also moving quite a lot of related
3229 code. They are in cfglayout.c. */
3230 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3231 extern basic_block cfg_layout_duplicate_bb (basic_block);
3234 rtl_duplicate_bb (basic_block bb)
3236 bb = cfg_layout_duplicate_bb (bb);
3241 /* Implementation of CFG manipulation for linearized RTL. */
3242 struct cfg_hooks rtl_cfg_hooks = {
3244 rtl_verify_flow_info,
3246 rtl_create_basic_block,
3247 rtl_redirect_edge_and_branch,
3248 rtl_redirect_edge_and_branch_force,
3249 rtl_can_remove_branch_p,
3252 rtl_move_block_after,
3253 rtl_can_merge_blocks, /* can_merge_blocks_p */
3257 cfg_layout_can_duplicate_bb_p,
3260 rtl_make_forwarder_block,
3261 rtl_tidy_fallthru_edge,
3262 rtl_force_nonfallthru,
3263 rtl_block_ends_with_call_p,
3264 rtl_block_ends_with_condjump_p,
3265 rtl_flow_call_edges_add,
3266 NULL, /* execute_on_growing_pred */
3267 NULL, /* execute_on_shrinking_pred */
3268 NULL, /* duplicate loop for trees */
3269 NULL, /* lv_add_condition_to_bb */
3270 NULL, /* lv_adjust_loop_header_phi*/
3271 NULL, /* extract_cond_bb_edges */
3272 NULL /* flush_pending_stmts */
3275 /* Implementation of CFG manipulation for cfg layout RTL, where
3276 basic block connected via fallthru edges does not have to be adjacent.
3277 This representation will hopefully become the default one in future
3278 version of the compiler. */
3280 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3282 rtl_verify_flow_info_1,
3284 cfg_layout_create_basic_block,
3285 cfg_layout_redirect_edge_and_branch,
3286 cfg_layout_redirect_edge_and_branch_force,
3287 rtl_can_remove_branch_p,
3288 cfg_layout_delete_block,
3289 cfg_layout_split_block,
3290 rtl_move_block_after,
3291 cfg_layout_can_merge_blocks_p,
3292 cfg_layout_merge_blocks,
3295 cfg_layout_can_duplicate_bb_p,
3296 cfg_layout_duplicate_bb,
3297 cfg_layout_split_edge,
3298 rtl_make_forwarder_block,
3299 NULL, /* tidy_fallthru_edge */
3300 rtl_force_nonfallthru,
3301 rtl_block_ends_with_call_p,
3302 rtl_block_ends_with_condjump_p,
3303 rtl_flow_call_edges_add,
3304 NULL, /* execute_on_growing_pred */
3305 NULL, /* execute_on_shrinking_pred */
3306 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3307 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3308 NULL, /* lv_adjust_loop_header_phi*/
3309 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3310 NULL /* flush_pending_stmts */