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 NOTE_INSN_BASIC_BLOCK of BB. */
505 bb_note (basic_block bb)
511 note = NEXT_INSN (note);
513 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (note));
517 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
518 note associated with the BLOCK. */
521 first_insn_after_basic_block_note (basic_block block)
525 /* Get the first instruction in the block. */
526 insn = BB_HEAD (block);
528 if (insn == NULL_RTX)
531 insn = NEXT_INSN (insn);
532 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
534 return NEXT_INSN (insn);
537 /* Creates a new basic block just after basic block B by splitting
538 everything after specified instruction I. */
541 rtl_split_block (basic_block bb, void *insnp)
544 rtx insn = (rtx) insnp;
550 insn = first_insn_after_basic_block_note (bb);
556 insn = PREV_INSN (insn);
558 /* If the block contains only debug insns, insn would have
559 been NULL in a non-debug compilation, and then we'd end
560 up emitting a DELETED note. For -fcompare-debug
561 stability, emit the note too. */
562 if (insn != BB_END (bb)
563 && DEBUG_INSN_P (next)
564 && DEBUG_INSN_P (BB_END (bb)))
566 while (next != BB_END (bb) && DEBUG_INSN_P (next))
567 next = NEXT_INSN (next);
569 if (next == BB_END (bb))
570 emit_note_after (NOTE_INSN_DELETED, next);
574 insn = get_last_insn ();
577 /* We probably should check type of the insn so that we do not create
578 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
580 if (insn == BB_END (bb))
581 emit_note_after (NOTE_INSN_DELETED, insn);
583 /* Create the new basic block. */
584 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
585 BB_COPY_PARTITION (new_bb, bb);
588 /* Redirect the outgoing edges. */
589 new_bb->succs = bb->succs;
591 FOR_EACH_EDGE (e, ei, new_bb->succs)
594 /* The new block starts off being dirty. */
595 df_set_bb_dirty (bb);
599 /* Blocks A and B are to be merged into a single block A. The insns
600 are already contiguous. */
603 rtl_merge_blocks (basic_block a, basic_block b)
605 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
606 rtx del_first = NULL_RTX, del_last = NULL_RTX;
607 rtx b_debug_start = b_end, b_debug_end = b_end;
608 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
612 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
615 while (DEBUG_INSN_P (b_end))
616 b_end = PREV_INSN (b_debug_start = b_end);
618 /* If there was a CODE_LABEL beginning B, delete it. */
619 if (LABEL_P (b_head))
621 /* Detect basic blocks with nothing but a label. This can happen
622 in particular at the end of a function. */
626 del_first = del_last = b_head;
627 b_head = NEXT_INSN (b_head);
630 /* Delete the basic block note and handle blocks containing just that
632 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
640 b_head = NEXT_INSN (b_head);
643 /* If there was a jump out of A, delete it. */
648 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
650 || NOTE_INSN_BASIC_BLOCK_P (prev)
651 || prev == BB_HEAD (a))
657 /* If this was a conditional jump, we need to also delete
658 the insn that set cc0. */
659 if (only_sets_cc0_p (prev))
663 prev = prev_nonnote_insn (prev);
670 a_end = PREV_INSN (del_first);
672 else if (BARRIER_P (NEXT_INSN (a_end)))
673 del_first = NEXT_INSN (a_end);
675 /* Delete everything marked above as well as crap that might be
676 hanging out between the two blocks. */
678 delete_insn_chain (del_first, del_last, true);
680 /* Reassociate the insns of B with A. */
683 update_bb_for_insn_chain (a_end, b_debug_end, a);
687 else if (b_end != b_debug_end)
689 /* Move any deleted labels and other notes between the end of A
690 and the debug insns that make up B after the debug insns,
691 bringing the debug insns into A while keeping the notes after
693 if (NEXT_INSN (a_end) != b_debug_start)
694 reorder_insns_nobb (NEXT_INSN (a_end), PREV_INSN (b_debug_start),
696 update_bb_for_insn_chain (b_debug_start, b_debug_end, a);
700 df_bb_delete (b->index);
703 /* If B was a forwarder block, propagate the locus on the edge. */
704 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
705 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
708 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
712 /* Return true when block A and B can be merged. */
715 rtl_can_merge_blocks (basic_block a, basic_block b)
717 /* If we are partitioning hot/cold basic blocks, we don't want to
718 mess up unconditional or indirect jumps that cross between hot
721 Basic block partitioning may result in some jumps that appear to
722 be optimizable (or blocks that appear to be mergeable), but which really
723 must be left untouched (they are required to make it safely across
724 partition boundaries). See the comments at the top of
725 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
727 if (BB_PARTITION (a) != BB_PARTITION (b))
730 /* There must be exactly one edge in between the blocks. */
731 return (single_succ_p (a)
732 && single_succ (a) == b
735 /* Must be simple edge. */
736 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
738 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
739 /* If the jump insn has side effects,
740 we can't kill the edge. */
741 && (!JUMP_P (BB_END (a))
743 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
746 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
750 block_label (basic_block block)
752 if (block == EXIT_BLOCK_PTR)
755 if (!LABEL_P (BB_HEAD (block)))
757 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
760 return BB_HEAD (block);
763 /* Attempt to perform edge redirection by replacing possibly complex jump
764 instruction by unconditional jump or removing jump completely. This can
765 apply only if all edges now point to the same block. The parameters and
766 return values are equivalent to redirect_edge_and_branch. */
769 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
771 basic_block src = e->src;
772 rtx insn = BB_END (src), kill_from;
776 /* If we are partitioning hot/cold basic blocks, we don't want to
777 mess up unconditional or indirect jumps that cross between hot
780 Basic block partitioning may result in some jumps that appear to
781 be optimizable (or blocks that appear to be mergeable), but which really
782 must be left untouched (they are required to make it safely across
783 partition boundaries). See the comments at the top of
784 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
786 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
787 || BB_PARTITION (src) != BB_PARTITION (target))
790 /* We can replace or remove a complex jump only when we have exactly
791 two edges. Also, if we have exactly one outgoing edge, we can
793 if (EDGE_COUNT (src->succs) >= 3
794 /* Verify that all targets will be TARGET. Specifically, the
795 edge that is not E must also go to TARGET. */
796 || (EDGE_COUNT (src->succs) == 2
797 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
800 if (!onlyjump_p (insn))
802 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
805 /* Avoid removing branch with side effects. */
806 set = single_set (insn);
807 if (!set || side_effects_p (set))
810 /* In case we zap a conditional jump, we'll need to kill
811 the cc0 setter too. */
814 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
815 && only_sets_cc0_p (PREV_INSN (insn)))
816 kill_from = PREV_INSN (insn);
819 /* See if we can create the fallthru edge. */
820 if (in_cfglayout || can_fallthru (src, target))
823 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
826 /* Selectively unlink whole insn chain. */
829 rtx insn = src->il.rtl->footer;
831 delete_insn_chain (kill_from, BB_END (src), false);
833 /* Remove barriers but keep jumptables. */
836 if (BARRIER_P (insn))
838 if (PREV_INSN (insn))
839 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
841 src->il.rtl->footer = NEXT_INSN (insn);
842 if (NEXT_INSN (insn))
843 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
847 insn = NEXT_INSN (insn);
851 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
855 /* If this already is simplejump, redirect it. */
856 else if (simplejump_p (insn))
858 if (e->dest == target)
861 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
862 INSN_UID (insn), e->dest->index, target->index);
863 if (!redirect_jump (insn, block_label (target), 0))
865 gcc_assert (target == EXIT_BLOCK_PTR);
870 /* Cannot do anything for target exit block. */
871 else if (target == EXIT_BLOCK_PTR)
874 /* Or replace possibly complicated jump insn by simple jump insn. */
877 rtx target_label = block_label (target);
878 rtx barrier, label, table;
880 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
881 JUMP_LABEL (BB_END (src)) = target_label;
882 LABEL_NUSES (target_label)++;
884 fprintf (dump_file, "Replacing insn %i by jump %i\n",
885 INSN_UID (insn), INSN_UID (BB_END (src)));
888 delete_insn_chain (kill_from, insn, false);
890 /* Recognize a tablejump that we are converting to a
891 simple jump and remove its associated CODE_LABEL
892 and ADDR_VEC or ADDR_DIFF_VEC. */
893 if (tablejump_p (insn, &label, &table))
894 delete_insn_chain (label, table, false);
896 barrier = next_nonnote_insn (BB_END (src));
897 if (!barrier || !BARRIER_P (barrier))
898 emit_barrier_after (BB_END (src));
901 if (barrier != NEXT_INSN (BB_END (src)))
903 /* Move the jump before barrier so that the notes
904 which originally were or were created before jump table are
905 inside the basic block. */
906 rtx new_insn = BB_END (src);
908 update_bb_for_insn_chain (NEXT_INSN (BB_END (src)),
909 PREV_INSN (barrier), src);
911 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
912 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
914 NEXT_INSN (new_insn) = barrier;
915 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
917 PREV_INSN (new_insn) = PREV_INSN (barrier);
918 PREV_INSN (barrier) = new_insn;
923 /* Keep only one edge out and set proper flags. */
924 if (!single_succ_p (src))
926 gcc_assert (single_succ_p (src));
928 e = single_succ_edge (src);
930 e->flags = EDGE_FALLTHRU;
934 e->probability = REG_BR_PROB_BASE;
935 e->count = src->count;
937 if (e->dest != target)
938 redirect_edge_succ (e, target);
942 /* Subroutine of redirect_branch_edge that tries to patch the jump
943 instruction INSN so that it reaches block NEW. Do this
944 only when it originally reached block OLD. Return true if this
945 worked or the original target wasn't OLD, return false if redirection
949 patch_jump_insn (rtx insn, rtx old_label, basic_block new_bb)
952 /* Recognize a tablejump and adjust all matching cases. */
953 if (tablejump_p (insn, NULL, &tmp))
957 rtx new_label = block_label (new_bb);
959 if (new_bb == EXIT_BLOCK_PTR)
961 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
962 vec = XVEC (PATTERN (tmp), 0);
964 vec = XVEC (PATTERN (tmp), 1);
966 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
967 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
969 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
970 --LABEL_NUSES (old_label);
971 ++LABEL_NUSES (new_label);
974 /* Handle casesi dispatch insns. */
975 if ((tmp = single_set (insn)) != NULL
976 && SET_DEST (tmp) == pc_rtx
977 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
978 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
979 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
981 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
983 --LABEL_NUSES (old_label);
984 ++LABEL_NUSES (new_label);
987 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
989 int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp);
992 if (new_bb == EXIT_BLOCK_PTR)
994 new_label = block_label (new_bb);
996 for (i = 0; i < n; ++i)
998 rtx old_ref = ASM_OPERANDS_LABEL (tmp, i);
999 gcc_assert (GET_CODE (old_ref) == LABEL_REF);
1000 if (XEXP (old_ref, 0) == old_label)
1002 ASM_OPERANDS_LABEL (tmp, i)
1003 = gen_rtx_LABEL_REF (Pmode, new_label);
1004 --LABEL_NUSES (old_label);
1005 ++LABEL_NUSES (new_label);
1009 if (JUMP_LABEL (insn) == old_label)
1011 JUMP_LABEL (insn) = new_label;
1012 note = find_reg_note (insn, REG_LABEL_TARGET, new_label);
1014 remove_note (insn, note);
1018 note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
1020 remove_note (insn, note);
1021 if (JUMP_LABEL (insn) != new_label
1022 && !find_reg_note (insn, REG_LABEL_TARGET, new_label))
1023 add_reg_note (insn, REG_LABEL_TARGET, new_label);
1025 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label))
1027 XEXP (note, 0) = new_label;
1031 /* ?? We may play the games with moving the named labels from
1032 one basic block to the other in case only one computed_jump is
1034 if (computed_jump_p (insn)
1035 /* A return instruction can't be redirected. */
1036 || returnjump_p (insn))
1039 if (!currently_expanding_to_rtl || JUMP_LABEL (insn) == old_label)
1041 /* If the insn doesn't go where we think, we're confused. */
1042 gcc_assert (JUMP_LABEL (insn) == old_label);
1044 /* If the substitution doesn't succeed, die. This can happen
1045 if the back end emitted unrecognizable instructions or if
1046 target is exit block on some arches. */
1047 if (!redirect_jump (insn, block_label (new_bb), 0))
1049 gcc_assert (new_bb == EXIT_BLOCK_PTR);
1058 /* Redirect edge representing branch of (un)conditional jump or tablejump,
1061 redirect_branch_edge (edge e, basic_block target)
1063 rtx old_label = BB_HEAD (e->dest);
1064 basic_block src = e->src;
1065 rtx insn = BB_END (src);
1067 /* We can only redirect non-fallthru edges of jump insn. */
1068 if (e->flags & EDGE_FALLTHRU)
1070 else if (!JUMP_P (insn) && !currently_expanding_to_rtl)
1073 if (!currently_expanding_to_rtl)
1075 if (!patch_jump_insn (insn, old_label, target))
1079 /* When expanding this BB might actually contain multiple
1080 jumps (i.e. not yet split by find_many_sub_basic_blocks).
1081 Redirect all of those that match our label. */
1082 FOR_BB_INSNS (src, insn)
1083 if (JUMP_P (insn) && !patch_jump_insn (insn, old_label, target))
1087 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
1088 e->src->index, e->dest->index, target->index);
1090 if (e->dest != target)
1091 e = redirect_edge_succ_nodup (e, target);
1096 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
1097 expense of adding new instructions or reordering basic blocks.
1099 Function can be also called with edge destination equivalent to the TARGET.
1100 Then it should try the simplifications and do nothing if none is possible.
1102 Return edge representing the branch if transformation succeeded. Return NULL
1104 We still return NULL in case E already destinated TARGET and we didn't
1105 managed to simplify instruction stream. */
1108 rtl_redirect_edge_and_branch (edge e, basic_block target)
1111 basic_block src = e->src;
1113 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
1116 if (e->dest == target)
1119 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
1121 df_set_bb_dirty (src);
1125 ret = redirect_branch_edge (e, target);
1129 df_set_bb_dirty (src);
1133 /* Like force_nonfallthru below, but additionally performs redirection
1134 Used by redirect_edge_and_branch_force. JUMP_LABEL is used only
1135 when redirecting to the EXIT_BLOCK, it is either ret_rtx or
1136 simple_return_rtx, indicating which kind of returnjump to create.
1137 It should be NULL otherwise. */
1140 force_nonfallthru_and_redirect (edge e, basic_block target, rtx jump_label)
1142 basic_block jump_block, new_bb = NULL, src = e->src;
1145 int abnormal_edge_flags = 0;
1146 bool asm_goto_edge = false;
1149 /* In the case the last instruction is conditional jump to the next
1150 instruction, first redirect the jump itself and then continue
1151 by creating a basic block afterwards to redirect fallthru edge. */
1152 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1153 && any_condjump_p (BB_END (e->src))
1154 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1157 edge b = unchecked_make_edge (e->src, target, 0);
1160 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1161 gcc_assert (redirected);
1163 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1166 int prob = INTVAL (XEXP (note, 0));
1168 b->probability = prob;
1169 b->count = e->count * prob / REG_BR_PROB_BASE;
1170 e->probability -= e->probability;
1171 e->count -= b->count;
1172 if (e->probability < 0)
1179 if (e->flags & EDGE_ABNORMAL)
1181 /* Irritating special case - fallthru edge to the same block as abnormal
1183 We can't redirect abnormal edge, but we still can split the fallthru
1184 one and create separate abnormal edge to original destination.
1185 This allows bb-reorder to make such edge non-fallthru. */
1186 gcc_assert (e->dest == target);
1187 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1188 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1192 gcc_assert (e->flags & EDGE_FALLTHRU);
1193 if (e->src == ENTRY_BLOCK_PTR)
1195 /* We can't redirect the entry block. Create an empty block
1196 at the start of the function which we use to add the new
1202 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1204 /* Change the existing edge's source to be the new block, and add
1205 a new edge from the entry block to the new block. */
1207 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1211 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1221 VEC_safe_push (edge, gc, bb->succs, e);
1222 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1226 /* If e->src ends with asm goto, see if any of the ASM_OPERANDS_LABELs
1227 don't point to target label. */
1228 if (JUMP_P (BB_END (e->src))
1229 && target != EXIT_BLOCK_PTR
1230 && e->dest == target
1231 && (e->flags & EDGE_FALLTHRU)
1232 && (note = extract_asm_operands (PATTERN (BB_END (e->src)))))
1234 int i, n = ASM_OPERANDS_LABEL_LENGTH (note);
1236 for (i = 0; i < n; ++i)
1237 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target))
1239 asm_goto_edge = true;
1244 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge)
1246 gcov_type count = e->count;
1247 int probability = e->probability;
1248 /* Create the new structures. */
1250 /* If the old block ended with a tablejump, skip its table
1251 by searching forward from there. Otherwise start searching
1252 forward from the last instruction of the old block. */
1253 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1254 note = BB_END (e->src);
1255 note = NEXT_INSN (note);
1257 jump_block = create_basic_block (note, NULL, e->src);
1258 jump_block->count = count;
1259 jump_block->frequency = EDGE_FREQUENCY (e);
1260 jump_block->loop_depth = target->loop_depth;
1262 /* Make sure new block ends up in correct hot/cold section. */
1264 BB_COPY_PARTITION (jump_block, e->src);
1265 if (flag_reorder_blocks_and_partition
1266 && targetm_common.have_named_sections
1267 && JUMP_P (BB_END (jump_block))
1268 && !any_condjump_p (BB_END (jump_block))
1269 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1270 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX);
1273 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1274 new_edge->probability = probability;
1275 new_edge->count = count;
1277 /* Redirect old edge. */
1278 redirect_edge_pred (e, jump_block);
1279 e->probability = REG_BR_PROB_BASE;
1281 /* If asm goto has any label refs to target's label,
1282 add also edge from asm goto bb to target. */
1285 new_edge->probability /= 2;
1286 new_edge->count /= 2;
1287 jump_block->count /= 2;
1288 jump_block->frequency /= 2;
1289 new_edge = make_edge (new_edge->src, target,
1290 e->flags & ~EDGE_FALLTHRU);
1291 new_edge->probability = probability - probability / 2;
1292 new_edge->count = count - count / 2;
1295 new_bb = jump_block;
1298 jump_block = e->src;
1300 if (e->goto_locus && e->goto_block == NULL)
1301 loc = e->goto_locus;
1304 e->flags &= ~EDGE_FALLTHRU;
1305 if (target == EXIT_BLOCK_PTR)
1307 if (jump_label == ret_rtx)
1310 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc);
1317 gcc_assert (jump_label == simple_return_rtx);
1318 #ifdef HAVE_simple_return
1319 emit_jump_insn_after_setloc (gen_simple_return (),
1320 BB_END (jump_block), loc);
1325 set_return_jump_label (BB_END (jump_block));
1329 rtx label = block_label (target);
1330 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc);
1331 JUMP_LABEL (BB_END (jump_block)) = label;
1332 LABEL_NUSES (label)++;
1335 emit_barrier_after (BB_END (jump_block));
1336 redirect_edge_succ_nodup (e, target);
1338 if (abnormal_edge_flags)
1339 make_edge (src, target, abnormal_edge_flags);
1341 df_mark_solutions_dirty ();
1345 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1346 (and possibly create new basic block) to make edge non-fallthru.
1347 Return newly created BB or NULL if none. */
1350 rtl_force_nonfallthru (edge e)
1352 return force_nonfallthru_and_redirect (e, e->dest, NULL_RTX);
1355 /* Redirect edge even at the expense of creating new jump insn or
1356 basic block. Return new basic block if created, NULL otherwise.
1357 Conversion must be possible. */
1360 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1362 if (redirect_edge_and_branch (e, target)
1363 || e->dest == target)
1366 /* In case the edge redirection failed, try to force it to be non-fallthru
1367 and redirect newly created simplejump. */
1368 df_set_bb_dirty (e->src);
1369 return force_nonfallthru_and_redirect (e, target, NULL_RTX);
1372 /* The given edge should potentially be a fallthru edge. If that is in
1373 fact true, delete the jump and barriers that are in the way. */
1376 rtl_tidy_fallthru_edge (edge e)
1379 basic_block b = e->src, c = b->next_bb;
1381 /* ??? In a late-running flow pass, other folks may have deleted basic
1382 blocks by nopping out blocks, leaving multiple BARRIERs between here
1383 and the target label. They ought to be chastised and fixed.
1385 We can also wind up with a sequence of undeletable labels between
1386 one block and the next.
1388 So search through a sequence of barriers, labels, and notes for
1389 the head of block C and assert that we really do fall through. */
1391 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1395 /* Remove what will soon cease being the jump insn from the source block.
1396 If block B consisted only of this single jump, turn it into a deleted
1401 && (any_uncondjump_p (q)
1402 || single_succ_p (b)))
1405 /* If this was a conditional jump, we need to also delete
1406 the insn that set cc0. */
1407 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1414 /* Selectively unlink the sequence. */
1415 if (q != PREV_INSN (BB_HEAD (c)))
1416 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false);
1418 e->flags |= EDGE_FALLTHRU;
1421 /* Should move basic block BB after basic block AFTER. NIY. */
1424 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1425 basic_block after ATTRIBUTE_UNUSED)
1430 /* Split a (typically critical) edge. Return the new block.
1431 The edge must not be abnormal.
1433 ??? The code generally expects to be called on critical edges.
1434 The case of a block ending in an unconditional jump to a
1435 block with multiple predecessors is not handled optimally. */
1438 rtl_split_edge (edge edge_in)
1443 /* Abnormal edges cannot be split. */
1444 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1446 /* We are going to place the new block in front of edge destination.
1447 Avoid existence of fallthru predecessors. */
1448 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1450 edge e = find_fallthru_edge (edge_in->dest->preds);
1453 force_nonfallthru (e);
1456 /* Create the basic block note. */
1457 if (edge_in->dest != EXIT_BLOCK_PTR)
1458 before = BB_HEAD (edge_in->dest);
1462 /* If this is a fall through edge to the exit block, the blocks might be
1463 not adjacent, and the right place is after the source. */
1464 if ((edge_in->flags & EDGE_FALLTHRU) && edge_in->dest == EXIT_BLOCK_PTR)
1466 before = NEXT_INSN (BB_END (edge_in->src));
1467 bb = create_basic_block (before, NULL, edge_in->src);
1468 BB_COPY_PARTITION (bb, edge_in->src);
1472 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1473 /* ??? Why not edge_in->dest->prev_bb here? */
1474 BB_COPY_PARTITION (bb, edge_in->dest);
1477 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1479 /* For non-fallthru edges, we must adjust the predecessor's
1480 jump instruction to target our new block. */
1481 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1483 edge redirected = redirect_edge_and_branch (edge_in, bb);
1484 gcc_assert (redirected);
1488 if (edge_in->src != ENTRY_BLOCK_PTR)
1490 /* For asm goto even splitting of fallthru edge might
1491 need insn patching, as other labels might point to the
1493 rtx last = BB_END (edge_in->src);
1496 && edge_in->dest != EXIT_BLOCK_PTR
1497 && extract_asm_operands (PATTERN (last)) != NULL_RTX
1498 && patch_jump_insn (last, before, bb))
1499 df_set_bb_dirty (edge_in->src);
1501 redirect_edge_succ (edge_in, bb);
1507 /* Queue instructions for insertion on an edge between two basic blocks.
1508 The new instructions and basic blocks (if any) will not appear in the
1509 CFG until commit_edge_insertions is called. */
1512 insert_insn_on_edge (rtx pattern, edge e)
1514 /* We cannot insert instructions on an abnormal critical edge.
1515 It will be easier to find the culprit if we die now. */
1516 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1518 if (e->insns.r == NULL_RTX)
1521 push_to_sequence (e->insns.r);
1523 emit_insn (pattern);
1525 e->insns.r = get_insns ();
1529 /* Update the CFG for the instructions queued on edge E. */
1532 commit_one_edge_insertion (edge e)
1534 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1537 /* Pull the insns off the edge now since the edge might go away. */
1539 e->insns.r = NULL_RTX;
1541 /* Figure out where to put these insns. If the destination has
1542 one predecessor, insert there. Except for the exit block. */
1543 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1547 /* Get the location correct wrt a code label, and "nice" wrt
1548 a basic block note, and before everything else. */
1551 tmp = NEXT_INSN (tmp);
1552 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1553 tmp = NEXT_INSN (tmp);
1554 if (tmp == BB_HEAD (bb))
1557 after = PREV_INSN (tmp);
1559 after = get_last_insn ();
1562 /* If the source has one successor and the edge is not abnormal,
1563 insert there. Except for the entry block. */
1564 else if ((e->flags & EDGE_ABNORMAL) == 0
1565 && single_succ_p (e->src)
1566 && e->src != ENTRY_BLOCK_PTR)
1570 /* It is possible to have a non-simple jump here. Consider a target
1571 where some forms of unconditional jumps clobber a register. This
1572 happens on the fr30 for example.
1574 We know this block has a single successor, so we can just emit
1575 the queued insns before the jump. */
1576 if (JUMP_P (BB_END (bb)))
1577 before = BB_END (bb);
1580 /* We'd better be fallthru, or we've lost track of what's what. */
1581 gcc_assert (e->flags & EDGE_FALLTHRU);
1583 after = BB_END (bb);
1587 /* Otherwise we must split the edge. */
1590 bb = split_edge (e);
1591 after = BB_END (bb);
1593 if (flag_reorder_blocks_and_partition
1594 && targetm_common.have_named_sections
1595 && e->src != ENTRY_BLOCK_PTR
1596 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1597 && !(e->flags & EDGE_CROSSING)
1599 && !any_condjump_p (after)
1600 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1601 add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX);
1604 /* Now that we've found the spot, do the insertion. */
1607 emit_insn_before_noloc (insns, before, bb);
1608 last = prev_nonnote_insn (before);
1611 last = emit_insn_after_noloc (insns, after, bb);
1613 if (returnjump_p (last))
1615 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1616 This is not currently a problem because this only happens
1617 for the (single) epilogue, which already has a fallthru edge
1620 e = single_succ_edge (bb);
1621 gcc_assert (e->dest == EXIT_BLOCK_PTR
1622 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1624 e->flags &= ~EDGE_FALLTHRU;
1625 emit_barrier_after (last);
1628 delete_insn (before);
1631 gcc_assert (!JUMP_P (last));
1634 /* Update the CFG for all queued instructions. */
1637 commit_edge_insertions (void)
1641 #ifdef ENABLE_CHECKING
1642 verify_flow_info ();
1645 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1650 FOR_EACH_EDGE (e, ei, bb->succs)
1652 commit_one_edge_insertion (e);
1657 /* Print out RTL-specific basic block information (live information
1658 at start and end). */
1661 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED)
1667 s_indent = (char *) alloca ((size_t) indent + 1);
1668 memset (s_indent, ' ', (size_t) indent);
1669 s_indent[indent] = '\0';
1673 df_dump_top (bb, outf);
1677 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1678 insn = NEXT_INSN (insn))
1679 print_rtl_single (outf, insn);
1683 df_dump_bottom (bb, outf);
1689 /* Like print_rtl, but also print out live information for the start of each
1693 print_rtl_with_bb (FILE *outf, const_rtx rtx_first)
1697 fprintf (outf, "(nil)\n");
1700 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1701 int max_uid = get_max_uid ();
1702 basic_block *start = XCNEWVEC (basic_block, max_uid);
1703 basic_block *end = XCNEWVEC (basic_block, max_uid);
1704 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1709 df_dump_start (outf);
1711 FOR_EACH_BB_REVERSE (bb)
1715 start[INSN_UID (BB_HEAD (bb))] = bb;
1716 end[INSN_UID (BB_END (bb))] = bb;
1717 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1719 enum bb_state state = IN_MULTIPLE_BB;
1721 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1723 in_bb_p[INSN_UID (x)] = state;
1725 if (x == BB_END (bb))
1730 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1734 bb = start[INSN_UID (tmp_rtx)];
1736 dump_bb_info (bb, true, false, dump_flags, ";; ", outf);
1738 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1739 && !NOTE_P (tmp_rtx)
1740 && !BARRIER_P (tmp_rtx))
1741 fprintf (outf, ";; Insn is not within a basic block\n");
1742 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1743 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1745 did_output = print_rtl_single (outf, tmp_rtx);
1747 bb = end[INSN_UID (tmp_rtx)];
1749 dump_bb_info (bb, false, true, dump_flags, ";; ", outf);
1759 if (crtl->epilogue_delay_list != 0)
1761 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1762 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0;
1763 tmp_rtx = XEXP (tmp_rtx, 1))
1764 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1769 update_br_prob_note (basic_block bb)
1772 if (!JUMP_P (BB_END (bb)))
1774 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1775 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1777 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1780 /* Get the last insn associated with block BB (that includes barriers and
1781 tablejumps after BB). */
1783 get_last_bb_insn (basic_block bb)
1786 rtx end = BB_END (bb);
1788 /* Include any jump table following the basic block. */
1789 if (tablejump_p (end, NULL, &tmp))
1792 /* Include any barriers that may follow the basic block. */
1793 tmp = next_nonnote_insn_bb (end);
1794 while (tmp && BARRIER_P (tmp))
1797 tmp = next_nonnote_insn_bb (end);
1803 /* Verify the CFG and RTL consistency common for both underlying RTL and
1806 Currently it does following checks:
1808 - overlapping of basic blocks
1809 - insns with wrong BLOCK_FOR_INSN pointers
1810 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1811 - tails of basic blocks (ensure that boundary is necessary)
1812 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1813 and NOTE_INSN_BASIC_BLOCK
1814 - verify that no fall_thru edge crosses hot/cold partition boundaries
1815 - verify that there are no pending RTL branch predictions
1817 In future it can be extended check a lot of other stuff as well
1818 (reachability of basic blocks, life information, etc. etc.). */
1821 rtl_verify_flow_info_1 (void)
1827 /* Check the general integrity of the basic blocks. */
1828 FOR_EACH_BB_REVERSE (bb)
1832 if (!(bb->flags & BB_RTL))
1834 error ("BB_RTL flag not set for block %d", bb->index);
1838 FOR_BB_INSNS (bb, insn)
1839 if (BLOCK_FOR_INSN (insn) != bb)
1841 error ("insn %d basic block pointer is %d, should be %d",
1843 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1848 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1849 if (!BARRIER_P (insn)
1850 && BLOCK_FOR_INSN (insn) != NULL)
1852 error ("insn %d in header of bb %d has non-NULL basic block",
1853 INSN_UID (insn), bb->index);
1856 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1857 if (!BARRIER_P (insn)
1858 && BLOCK_FOR_INSN (insn) != NULL)
1860 error ("insn %d in footer of bb %d has non-NULL basic block",
1861 INSN_UID (insn), bb->index);
1866 /* Now check the basic blocks (boundaries etc.) */
1867 FOR_EACH_BB_REVERSE (bb)
1869 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1870 edge e, fallthru = NULL;
1874 if (JUMP_P (BB_END (bb))
1875 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1876 && EDGE_COUNT (bb->succs) >= 2
1877 && any_condjump_p (BB_END (bb)))
1879 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1880 && profile_status != PROFILE_ABSENT)
1882 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1883 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1887 FOR_EACH_EDGE (e, ei, bb->succs)
1891 if (e->flags & EDGE_FALLTHRU)
1892 n_fallthru++, fallthru = e;
1894 is_crossing = (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1895 && e->src != ENTRY_BLOCK_PTR
1896 && e->dest != EXIT_BLOCK_PTR);
1897 if (e->flags & EDGE_CROSSING)
1901 error ("EDGE_CROSSING incorrectly set across same section");
1904 if (e->flags & EDGE_FALLTHRU)
1906 error ("fallthru edge crosses section boundary (bb %i)",
1910 if (e->flags & EDGE_EH)
1912 error ("EH edge crosses section boundary (bb %i)",
1917 else if (is_crossing)
1919 error ("EDGE_CROSSING missing across section boundary");
1923 if ((e->flags & ~(EDGE_DFS_BACK
1925 | EDGE_IRREDUCIBLE_LOOP
1928 | EDGE_PRESERVE)) == 0)
1931 if (e->flags & EDGE_ABNORMAL_CALL)
1934 if (e->flags & EDGE_EH)
1936 else if (e->flags & EDGE_ABNORMAL)
1940 if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1942 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1947 error ("too many eh edges %i", bb->index);
1951 && (!JUMP_P (BB_END (bb))
1952 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1953 || any_condjump_p (BB_END (bb))))))
1955 error ("too many outgoing branch edges from bb %i", bb->index);
1958 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1960 error ("fallthru edge after unconditional jump %i", bb->index);
1963 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1965 error ("wrong number of branch edges after unconditional jump %i",
1969 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1970 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1972 error ("wrong amount of branch edges after conditional jump %i",
1976 if (n_call && !CALL_P (BB_END (bb)))
1978 error ("call edges for non-call insn in bb %i", bb->index);
1982 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1983 && (!JUMP_P (BB_END (bb))
1984 || any_condjump_p (BB_END (bb))
1985 || any_uncondjump_p (BB_END (bb))))
1987 error ("abnormal edges for no purpose in bb %i", bb->index);
1991 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1992 /* We may have a barrier inside a basic block before dead code
1993 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1994 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1997 if (! BLOCK_FOR_INSN (x))
1999 ("insn %d inside basic block %d but block_for_insn is NULL",
2000 INSN_UID (x), bb->index);
2003 ("insn %d inside basic block %d but block_for_insn is %i",
2004 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2009 /* OK pointers are correct. Now check the header of basic
2010 block. It ought to contain optional CODE_LABEL followed
2011 by NOTE_BASIC_BLOCK. */
2015 if (BB_END (bb) == x)
2017 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2025 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2027 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2032 if (BB_END (bb) == x)
2033 /* Do checks for empty blocks here. */
2036 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2038 if (NOTE_INSN_BASIC_BLOCK_P (x))
2040 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2041 INSN_UID (x), bb->index);
2045 if (x == BB_END (bb))
2048 if (control_flow_insn_p (x))
2050 error ("in basic block %d:", bb->index);
2051 fatal_insn ("flow control insn inside a basic block", x);
2060 /* Verify the CFG and RTL consistency common for both underlying RTL and
2063 Currently it does following checks:
2064 - all checks of rtl_verify_flow_info_1
2065 - test head/end pointers
2066 - check that all insns are in the basic blocks
2067 (except the switch handling code, barriers and notes)
2068 - check that all returns are followed by barriers
2069 - check that all fallthru edge points to the adjacent blocks. */
2072 rtl_verify_flow_info (void)
2075 int err = rtl_verify_flow_info_1 ();
2077 rtx last_head = get_last_insn ();
2078 basic_block *bb_info;
2080 const rtx rtx_first = get_insns ();
2081 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2082 const int max_uid = get_max_uid ();
2084 bb_info = XCNEWVEC (basic_block, max_uid);
2086 FOR_EACH_BB_REVERSE (bb)
2089 rtx head = BB_HEAD (bb);
2090 rtx end = BB_END (bb);
2092 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2094 /* Verify the end of the basic block is in the INSN chain. */
2098 /* And that the code outside of basic blocks has NULL bb field. */
2100 && BLOCK_FOR_INSN (x) != NULL)
2102 error ("insn %d outside of basic blocks has non-NULL bb field",
2110 error ("end insn %d for block %d not found in the insn stream",
2111 INSN_UID (end), bb->index);
2115 /* Work backwards from the end to the head of the basic block
2116 to verify the head is in the RTL chain. */
2117 for (; x != NULL_RTX; x = PREV_INSN (x))
2119 /* While walking over the insn chain, verify insns appear
2120 in only one basic block. */
2121 if (bb_info[INSN_UID (x)] != NULL)
2123 error ("insn %d is in multiple basic blocks (%d and %d)",
2124 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
2128 bb_info[INSN_UID (x)] = bb;
2135 error ("head insn %d for block %d not found in the insn stream",
2136 INSN_UID (head), bb->index);
2140 last_head = PREV_INSN (x);
2142 e = find_fallthru_edge (bb->succs);
2147 /* Ensure existence of barrier in BB with no fallthru edges. */
2148 for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn))
2150 if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn))
2152 error ("missing barrier after block %i", bb->index);
2156 if (BARRIER_P (insn))
2160 else if (e->src != ENTRY_BLOCK_PTR
2161 && e->dest != EXIT_BLOCK_PTR)
2165 if (e->src->next_bb != e->dest)
2168 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2169 e->src->index, e->dest->index);
2173 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2174 insn = NEXT_INSN (insn))
2175 if (BARRIER_P (insn) || INSN_P (insn))
2177 error ("verify_flow_info: Incorrect fallthru %i->%i",
2178 e->src->index, e->dest->index);
2179 fatal_insn ("wrong insn in the fallthru edge", insn);
2185 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2187 /* Check that the code before the first basic block has NULL
2190 && BLOCK_FOR_INSN (x) != NULL)
2192 error ("insn %d outside of basic blocks has non-NULL bb field",
2200 last_bb_seen = ENTRY_BLOCK_PTR;
2202 for (x = rtx_first; x; x = NEXT_INSN (x))
2204 if (NOTE_INSN_BASIC_BLOCK_P (x))
2206 bb = NOTE_BASIC_BLOCK (x);
2209 if (bb != last_bb_seen->next_bb)
2210 internal_error ("basic blocks not laid down consecutively");
2212 curr_bb = last_bb_seen = bb;
2217 switch (GET_CODE (x))
2224 /* An addr_vec is placed outside any basic block. */
2226 && JUMP_TABLE_DATA_P (NEXT_INSN (x)))
2229 /* But in any case, non-deletable labels can appear anywhere. */
2233 fatal_insn ("insn outside basic block", x);
2238 && returnjump_p (x) && ! condjump_p (x)
2239 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2240 fatal_insn ("return not followed by barrier", x);
2241 if (curr_bb && x == BB_END (curr_bb))
2245 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2247 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2248 num_bb_notes, n_basic_blocks);
2253 /* Assume that the preceding pass has possibly eliminated jump instructions
2254 or converted the unconditional jumps. Eliminate the edges from CFG.
2255 Return true if any edges are eliminated. */
2258 purge_dead_edges (basic_block bb)
2261 rtx insn = BB_END (bb), note;
2262 bool purged = false;
2266 if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb))
2268 insn = PREV_INSN (insn);
2269 while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb));
2271 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2272 if (NONJUMP_INSN_P (insn)
2273 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2277 if (! may_trap_p (PATTERN (insn))
2278 || ((eqnote = find_reg_equal_equiv_note (insn))
2279 && ! may_trap_p (XEXP (eqnote, 0))))
2280 remove_note (insn, note);
2283 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2284 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2286 bool remove = false;
2288 /* There are three types of edges we need to handle correctly here: EH
2289 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2290 latter can appear when nonlocal gotos are used. */
2291 if (e->flags & EDGE_ABNORMAL_CALL)
2295 else if (can_nonlocal_goto (insn))
2297 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2299 else if (flag_tm && find_reg_note (insn, REG_TM, NULL))
2304 else if (e->flags & EDGE_EH)
2305 remove = !can_throw_internal (insn);
2310 df_set_bb_dirty (bb);
2323 /* We do care only about conditional jumps and simplejumps. */
2324 if (!any_condjump_p (insn)
2325 && !returnjump_p (insn)
2326 && !simplejump_p (insn))
2329 /* Branch probability/prediction notes are defined only for
2330 condjumps. We've possibly turned condjump into simplejump. */
2331 if (simplejump_p (insn))
2333 note = find_reg_note (insn, REG_BR_PROB, NULL);
2335 remove_note (insn, note);
2336 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2337 remove_note (insn, note);
2340 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2342 /* Avoid abnormal flags to leak from computed jumps turned
2343 into simplejumps. */
2345 e->flags &= ~EDGE_ABNORMAL;
2347 /* See if this edge is one we should keep. */
2348 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2349 /* A conditional jump can fall through into the next
2350 block, so we should keep the edge. */
2355 else if (e->dest != EXIT_BLOCK_PTR
2356 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2357 /* If the destination block is the target of the jump,
2363 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2364 /* If the destination block is the exit block, and this
2365 instruction is a return, then keep the edge. */
2370 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2371 /* Keep the edges that correspond to exceptions thrown by
2372 this instruction and rematerialize the EDGE_ABNORMAL
2373 flag we just cleared above. */
2375 e->flags |= EDGE_ABNORMAL;
2380 /* We do not need this edge. */
2381 df_set_bb_dirty (bb);
2386 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2390 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2395 /* Redistribute probabilities. */
2396 if (single_succ_p (bb))
2398 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2399 single_succ_edge (bb)->count = bb->count;
2403 note = find_reg_note (insn, REG_BR_PROB, NULL);
2407 b = BRANCH_EDGE (bb);
2408 f = FALLTHRU_EDGE (bb);
2409 b->probability = INTVAL (XEXP (note, 0));
2410 f->probability = REG_BR_PROB_BASE - b->probability;
2411 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2412 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2417 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2419 /* First, there should not be any EH or ABCALL edges resulting
2420 from non-local gotos and the like. If there were, we shouldn't
2421 have created the sibcall in the first place. Second, there
2422 should of course never have been a fallthru edge. */
2423 gcc_assert (single_succ_p (bb));
2424 gcc_assert (single_succ_edge (bb)->flags
2425 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2430 /* If we don't see a jump insn, we don't know exactly why the block would
2431 have been broken at this point. Look for a simple, non-fallthru edge,
2432 as these are only created by conditional branches. If we find such an
2433 edge we know that there used to be a jump here and can then safely
2434 remove all non-fallthru edges. */
2436 FOR_EACH_EDGE (e, ei, bb->succs)
2437 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2446 /* Remove all but the fake and fallthru edges. The fake edge may be
2447 the only successor for this block in the case of noreturn
2449 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2451 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2453 df_set_bb_dirty (bb);
2461 gcc_assert (single_succ_p (bb));
2463 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2464 single_succ_edge (bb)->count = bb->count;
2467 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2472 /* Search all basic blocks for potentially dead edges and purge them. Return
2473 true if some edge has been eliminated. */
2476 purge_all_dead_edges (void)
2483 bool purged_here = purge_dead_edges (bb);
2485 purged |= purged_here;
2491 /* This is used by a few passes that emit some instructions after abnormal
2492 calls, moving the basic block's end, while they in fact do want to emit
2493 them on the fallthru edge. Look for abnormal call edges, find backward
2494 the call in the block and insert the instructions on the edge instead.
2496 Similarly, handle instructions throwing exceptions internally.
2498 Return true when instructions have been found and inserted on edges. */
2501 fixup_abnormal_edges (void)
2503 bool inserted = false;
2511 /* Look for cases we are interested in - calls or instructions causing
2513 FOR_EACH_EDGE (e, ei, bb->succs)
2514 if ((e->flags & EDGE_ABNORMAL_CALL)
2515 || ((e->flags & (EDGE_ABNORMAL | EDGE_EH))
2516 == (EDGE_ABNORMAL | EDGE_EH)))
2519 if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb)))
2523 /* Get past the new insns generated. Allow notes, as the insns
2524 may be already deleted. */
2526 while ((NONJUMP_INSN_P (insn) || NOTE_P (insn))
2527 && !can_throw_internal (insn)
2528 && insn != BB_HEAD (bb))
2529 insn = PREV_INSN (insn);
2531 if (CALL_P (insn) || can_throw_internal (insn))
2535 e = find_fallthru_edge (bb->succs);
2537 stop = NEXT_INSN (BB_END (bb));
2540 for (insn = NEXT_INSN (insn); insn != stop; insn = next)
2542 next = NEXT_INSN (insn);
2547 /* Sometimes there's still the return value USE.
2548 If it's placed after a trapping call (i.e. that
2549 call is the last insn anyway), we have no fallthru
2550 edge. Simply delete this use and don't try to insert
2551 on the non-existent edge. */
2552 if (GET_CODE (PATTERN (insn)) != USE)
2554 /* We're not deleting it, we're moving it. */
2555 INSN_DELETED_P (insn) = 0;
2556 PREV_INSN (insn) = NULL_RTX;
2557 NEXT_INSN (insn) = NULL_RTX;
2559 insert_insn_on_edge (insn, e);
2563 else if (!BARRIER_P (insn))
2564 set_block_for_insn (insn, NULL);
2568 /* It may be that we don't find any trapping insn. In this
2569 case we discovered quite late that the insn that had been
2570 marked as can_throw_internal in fact couldn't trap at all.
2571 So we should in fact delete the EH edges out of the block. */
2573 purge_dead_edges (bb);
2580 /* Same as split_block but update cfg_layout structures. */
2583 cfg_layout_split_block (basic_block bb, void *insnp)
2585 rtx insn = (rtx) insnp;
2586 basic_block new_bb = rtl_split_block (bb, insn);
2588 new_bb->il.rtl->footer = bb->il.rtl->footer;
2589 bb->il.rtl->footer = NULL;
2594 /* Redirect Edge to DEST. */
2596 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2598 basic_block src = e->src;
2601 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2604 if (e->dest == dest)
2607 if (e->src != ENTRY_BLOCK_PTR
2608 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2610 df_set_bb_dirty (src);
2614 if (e->src == ENTRY_BLOCK_PTR
2615 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2618 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2619 e->src->index, dest->index);
2621 df_set_bb_dirty (e->src);
2622 redirect_edge_succ (e, dest);
2626 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2627 in the case the basic block appears to be in sequence. Avoid this
2630 if (e->flags & EDGE_FALLTHRU)
2632 /* Redirect any branch edges unified with the fallthru one. */
2633 if (JUMP_P (BB_END (src))
2634 && label_is_jump_target_p (BB_HEAD (e->dest),
2640 fprintf (dump_file, "Fallthru edge unified with branch "
2641 "%i->%i redirected to %i\n",
2642 e->src->index, e->dest->index, dest->index);
2643 e->flags &= ~EDGE_FALLTHRU;
2644 redirected = redirect_branch_edge (e, dest);
2645 gcc_assert (redirected);
2646 redirected->flags |= EDGE_FALLTHRU;
2647 df_set_bb_dirty (redirected->src);
2650 /* In case we are redirecting fallthru edge to the branch edge
2651 of conditional jump, remove it. */
2652 if (EDGE_COUNT (src->succs) == 2)
2654 /* Find the edge that is different from E. */
2655 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2658 && any_condjump_p (BB_END (src))
2659 && onlyjump_p (BB_END (src)))
2660 delete_insn (BB_END (src));
2663 fprintf (dump_file, "Redirecting fallthru edge %i->%i to %i\n",
2664 e->src->index, e->dest->index, dest->index);
2665 ret = redirect_edge_succ_nodup (e, dest);
2668 ret = redirect_branch_edge (e, dest);
2670 /* We don't want simplejumps in the insn stream during cfglayout. */
2671 gcc_assert (!simplejump_p (BB_END (src)));
2673 df_set_bb_dirty (src);
2677 /* Simple wrapper as we always can redirect fallthru edges. */
2679 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2681 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2683 gcc_assert (redirected);
2687 /* Same as delete_basic_block but update cfg_layout structures. */
2690 cfg_layout_delete_block (basic_block bb)
2692 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2694 if (bb->il.rtl->header)
2696 next = BB_HEAD (bb);
2698 NEXT_INSN (prev) = bb->il.rtl->header;
2700 set_first_insn (bb->il.rtl->header);
2701 PREV_INSN (bb->il.rtl->header) = prev;
2702 insn = bb->il.rtl->header;
2703 while (NEXT_INSN (insn))
2704 insn = NEXT_INSN (insn);
2705 NEXT_INSN (insn) = next;
2706 PREV_INSN (next) = insn;
2708 next = NEXT_INSN (BB_END (bb));
2709 if (bb->il.rtl->footer)
2711 insn = bb->il.rtl->footer;
2714 if (BARRIER_P (insn))
2716 if (PREV_INSN (insn))
2717 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2719 bb->il.rtl->footer = NEXT_INSN (insn);
2720 if (NEXT_INSN (insn))
2721 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2725 insn = NEXT_INSN (insn);
2727 if (bb->il.rtl->footer)
2730 NEXT_INSN (insn) = bb->il.rtl->footer;
2731 PREV_INSN (bb->il.rtl->footer) = insn;
2732 while (NEXT_INSN (insn))
2733 insn = NEXT_INSN (insn);
2734 NEXT_INSN (insn) = next;
2736 PREV_INSN (next) = insn;
2738 set_last_insn (insn);
2741 if (bb->next_bb != EXIT_BLOCK_PTR)
2742 to = &bb->next_bb->il.rtl->header;
2744 to = &cfg_layout_function_footer;
2746 rtl_delete_block (bb);
2749 prev = NEXT_INSN (prev);
2751 prev = get_insns ();
2753 next = PREV_INSN (next);
2755 next = get_last_insn ();
2757 if (next && NEXT_INSN (next) != prev)
2759 remaints = unlink_insn_chain (prev, next);
2761 while (NEXT_INSN (insn))
2762 insn = NEXT_INSN (insn);
2763 NEXT_INSN (insn) = *to;
2765 PREV_INSN (*to) = insn;
2770 /* Return true when blocks A and B can be safely merged. */
2773 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2775 /* If we are partitioning hot/cold basic blocks, we don't want to
2776 mess up unconditional or indirect jumps that cross between hot
2779 Basic block partitioning may result in some jumps that appear to
2780 be optimizable (or blocks that appear to be mergeable), but which really
2781 must be left untouched (they are required to make it safely across
2782 partition boundaries). See the comments at the top of
2783 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2785 if (BB_PARTITION (a) != BB_PARTITION (b))
2788 /* If we would end up moving B's instructions, make sure it doesn't fall
2789 through into the exit block, since we cannot recover from a fallthrough
2790 edge into the exit block occurring in the middle of a function. */
2791 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2793 edge e = find_fallthru_edge (b->succs);
2794 if (e && e->dest == EXIT_BLOCK_PTR)
2798 /* There must be exactly one edge in between the blocks. */
2799 return (single_succ_p (a)
2800 && single_succ (a) == b
2801 && single_pred_p (b) == 1
2803 /* Must be simple edge. */
2804 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2805 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2806 /* If the jump insn has side effects, we can't kill the edge.
2807 When not optimizing, try_redirect_by_replacing_jump will
2808 not allow us to redirect an edge by replacing a table jump. */
2809 && (!JUMP_P (BB_END (a))
2810 || ((!optimize || reload_completed)
2811 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2814 /* Merge block A and B. The blocks must be mergeable. */
2817 cfg_layout_merge_blocks (basic_block a, basic_block b)
2819 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
2821 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b));
2824 fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
2827 /* If there was a CODE_LABEL beginning B, delete it. */
2828 if (LABEL_P (BB_HEAD (b)))
2830 delete_insn (BB_HEAD (b));
2833 /* We should have fallthru edge in a, or we can do dummy redirection to get
2835 if (JUMP_P (BB_END (a)))
2836 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2837 gcc_assert (!JUMP_P (BB_END (a)));
2839 /* When not optimizing and the edge is the only place in RTL which holds
2840 some unique locus, emit a nop with that locus in between. */
2841 if (!optimize && EDGE_SUCC (a, 0)->goto_locus)
2843 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a));
2844 int goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2846 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
2847 insn = PREV_INSN (insn);
2848 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus))
2853 end = NEXT_INSN (BB_END (b));
2854 while (insn != end && !INSN_P (insn))
2855 insn = NEXT_INSN (insn);
2856 if (insn != end && INSN_LOCATOR (insn) != 0
2857 && locator_eq (INSN_LOCATOR (insn), goto_locus))
2862 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a);
2863 INSN_LOCATOR (BB_END (a)) = goto_locus;
2867 /* Possible line number notes should appear in between. */
2868 if (b->il.rtl->header)
2870 rtx first = BB_END (a), last;
2872 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2873 delete_insn_chain (NEXT_INSN (first), last, false);
2874 b->il.rtl->header = NULL;
2877 /* In the case basic blocks are not adjacent, move them around. */
2878 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2880 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2882 emit_insn_after_noloc (first, BB_END (a), a);
2883 /* Skip possible DELETED_LABEL insn. */
2884 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2885 first = NEXT_INSN (first);
2886 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2889 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
2890 We need to explicitly call. */
2891 update_bb_for_insn_chain (NEXT_INSN (first),
2895 delete_insn (first);
2897 /* Otherwise just re-associate the instructions. */
2902 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a);
2905 /* Skip possible DELETED_LABEL insn. */
2906 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2907 insn = NEXT_INSN (insn);
2908 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2910 BB_END (a) = BB_END (b);
2914 df_bb_delete (b->index);
2916 /* Possible tablejumps and barriers should appear after the block. */
2917 if (b->il.rtl->footer)
2919 if (!a->il.rtl->footer)
2920 a->il.rtl->footer = b->il.rtl->footer;
2923 rtx last = a->il.rtl->footer;
2925 while (NEXT_INSN (last))
2926 last = NEXT_INSN (last);
2927 NEXT_INSN (last) = b->il.rtl->footer;
2928 PREV_INSN (b->il.rtl->footer) = last;
2930 b->il.rtl->footer = NULL;
2933 /* If B was a forwarder block, propagate the locus on the edge. */
2934 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
2935 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2938 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
2944 cfg_layout_split_edge (edge e)
2946 basic_block new_bb =
2947 create_basic_block (e->src != ENTRY_BLOCK_PTR
2948 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2951 if (e->dest == EXIT_BLOCK_PTR)
2952 BB_COPY_PARTITION (new_bb, e->src);
2954 BB_COPY_PARTITION (new_bb, e->dest);
2955 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2956 redirect_edge_and_branch_force (e, new_bb);
2961 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2964 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2968 /* Return 1 if BB ends with a call, possibly followed by some
2969 instructions that must stay with the call, 0 otherwise. */
2972 rtl_block_ends_with_call_p (basic_block bb)
2974 rtx insn = BB_END (bb);
2976 while (!CALL_P (insn)
2977 && insn != BB_HEAD (bb)
2978 && (keep_with_call_p (insn)
2980 || DEBUG_INSN_P (insn)))
2981 insn = PREV_INSN (insn);
2982 return (CALL_P (insn));
2985 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2988 rtl_block_ends_with_condjump_p (const_basic_block bb)
2990 return any_condjump_p (BB_END (bb));
2993 /* Return true if we need to add fake edge to exit.
2994 Helper function for rtl_flow_call_edges_add. */
2997 need_fake_edge_p (const_rtx insn)
3003 && !SIBLING_CALL_P (insn)
3004 && !find_reg_note (insn, REG_NORETURN, NULL)
3005 && !(RTL_CONST_OR_PURE_CALL_P (insn))))
3008 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
3009 && MEM_VOLATILE_P (PATTERN (insn)))
3010 || (GET_CODE (PATTERN (insn)) == PARALLEL
3011 && asm_noperands (insn) != -1
3012 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
3013 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
3016 /* Add fake edges to the function exit for any non constant and non noreturn
3017 calls, volatile inline assembly in the bitmap of blocks specified by
3018 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
3021 The goal is to expose cases in which entering a basic block does not imply
3022 that all subsequent instructions must be executed. */
3025 rtl_flow_call_edges_add (sbitmap blocks)
3028 int blocks_split = 0;
3029 int last_bb = last_basic_block;
3030 bool check_last_block = false;
3032 if (n_basic_blocks == NUM_FIXED_BLOCKS)
3036 check_last_block = true;
3038 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
3040 /* In the last basic block, before epilogue generation, there will be
3041 a fallthru edge to EXIT. Special care is required if the last insn
3042 of the last basic block is a call because make_edge folds duplicate
3043 edges, which would result in the fallthru edge also being marked
3044 fake, which would result in the fallthru edge being removed by
3045 remove_fake_edges, which would result in an invalid CFG.
3047 Moreover, we can't elide the outgoing fake edge, since the block
3048 profiler needs to take this into account in order to solve the minimal
3049 spanning tree in the case that the call doesn't return.
3051 Handle this by adding a dummy instruction in a new last basic block. */
3052 if (check_last_block)
3054 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
3055 rtx insn = BB_END (bb);
3057 /* Back up past insns that must be kept in the same block as a call. */
3058 while (insn != BB_HEAD (bb)
3059 && keep_with_call_p (insn))
3060 insn = PREV_INSN (insn);
3062 if (need_fake_edge_p (insn))
3066 e = find_edge (bb, EXIT_BLOCK_PTR);
3069 insert_insn_on_edge (gen_use (const0_rtx), e);
3070 commit_edge_insertions ();
3075 /* Now add fake edges to the function exit for any non constant
3076 calls since there is no way that we can determine if they will
3079 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
3081 basic_block bb = BASIC_BLOCK (i);
3088 if (blocks && !TEST_BIT (blocks, i))
3091 for (insn = BB_END (bb); ; insn = prev_insn)
3093 prev_insn = PREV_INSN (insn);
3094 if (need_fake_edge_p (insn))
3097 rtx split_at_insn = insn;
3099 /* Don't split the block between a call and an insn that should
3100 remain in the same block as the call. */
3102 while (split_at_insn != BB_END (bb)
3103 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3104 split_at_insn = NEXT_INSN (split_at_insn);
3106 /* The handling above of the final block before the epilogue
3107 should be enough to verify that there is no edge to the exit
3108 block in CFG already. Calling make_edge in such case would
3109 cause us to mark that edge as fake and remove it later. */
3111 #ifdef ENABLE_CHECKING
3112 if (split_at_insn == BB_END (bb))
3114 e = find_edge (bb, EXIT_BLOCK_PTR);
3115 gcc_assert (e == NULL);
3119 /* Note that the following may create a new basic block
3120 and renumber the existing basic blocks. */
3121 if (split_at_insn != BB_END (bb))
3123 e = split_block (bb, split_at_insn);
3128 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3131 if (insn == BB_HEAD (bb))
3137 verify_flow_info ();
3139 return blocks_split;
3142 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
3143 the conditional branch target, SECOND_HEAD should be the fall-thru
3144 there is no need to handle this here the loop versioning code handles
3145 this. the reason for SECON_HEAD is that it is needed for condition
3146 in trees, and this should be of the same type since it is a hook. */
3148 rtl_lv_add_condition_to_bb (basic_block first_head ,
3149 basic_block second_head ATTRIBUTE_UNUSED,
3150 basic_block cond_bb, void *comp_rtx)
3152 rtx label, seq, jump;
3153 rtx op0 = XEXP ((rtx)comp_rtx, 0);
3154 rtx op1 = XEXP ((rtx)comp_rtx, 1);
3155 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
3156 enum machine_mode mode;
3159 label = block_label (first_head);
3160 mode = GET_MODE (op0);
3161 if (mode == VOIDmode)
3162 mode = GET_MODE (op1);
3165 op0 = force_operand (op0, NULL_RTX);
3166 op1 = force_operand (op1, NULL_RTX);
3167 do_compare_rtx_and_jump (op0, op1, comp, 0,
3168 mode, NULL_RTX, NULL_RTX, label, -1);
3169 jump = get_last_insn ();
3170 JUMP_LABEL (jump) = label;
3171 LABEL_NUSES (label)++;
3175 /* Add the new cond , in the new head. */
3176 emit_insn_after(seq, BB_END(cond_bb));
3180 /* Given a block B with unconditional branch at its end, get the
3181 store the return the branch edge and the fall-thru edge in
3182 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
3184 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
3185 edge *fallthru_edge)
3187 edge e = EDGE_SUCC (b, 0);
3189 if (e->flags & EDGE_FALLTHRU)
3192 *branch_edge = EDGE_SUCC (b, 1);
3197 *fallthru_edge = EDGE_SUCC (b, 1);
3202 init_rtl_bb_info (basic_block bb)
3204 gcc_assert (!bb->il.rtl);
3205 bb->il.rtl = ggc_alloc_cleared_rtl_bb_info ();
3208 /* Returns true if it is possible to remove edge E by redirecting
3209 it to the destination of the other edge from E->src. */
3212 rtl_can_remove_branch_p (const_edge e)
3214 const_basic_block src = e->src;
3215 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3216 const_rtx insn = BB_END (src), set;
3218 /* The conditions are taken from try_redirect_by_replacing_jump. */
3219 if (target == EXIT_BLOCK_PTR)
3222 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3225 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3226 || BB_PARTITION (src) != BB_PARTITION (target))
3229 if (!onlyjump_p (insn)
3230 || tablejump_p (insn, NULL, NULL))
3233 set = single_set (insn);
3234 if (!set || side_effects_p (set))
3240 /* We do not want to declare these functions in a header file, since they
3241 should only be used through the cfghooks interface, and we do not want to
3242 move them here since it would require also moving quite a lot of related
3243 code. They are in cfglayout.c. */
3244 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3245 extern basic_block cfg_layout_duplicate_bb (basic_block);
3248 rtl_duplicate_bb (basic_block bb)
3250 bb = cfg_layout_duplicate_bb (bb);
3255 /* Implementation of CFG manipulation for linearized RTL. */
3256 struct cfg_hooks rtl_cfg_hooks = {
3258 rtl_verify_flow_info,
3260 rtl_create_basic_block,
3261 rtl_redirect_edge_and_branch,
3262 rtl_redirect_edge_and_branch_force,
3263 rtl_can_remove_branch_p,
3266 rtl_move_block_after,
3267 rtl_can_merge_blocks, /* can_merge_blocks_p */
3271 cfg_layout_can_duplicate_bb_p,
3274 rtl_make_forwarder_block,
3275 rtl_tidy_fallthru_edge,
3276 rtl_force_nonfallthru,
3277 rtl_block_ends_with_call_p,
3278 rtl_block_ends_with_condjump_p,
3279 rtl_flow_call_edges_add,
3280 NULL, /* execute_on_growing_pred */
3281 NULL, /* execute_on_shrinking_pred */
3282 NULL, /* duplicate loop for trees */
3283 NULL, /* lv_add_condition_to_bb */
3284 NULL, /* lv_adjust_loop_header_phi*/
3285 NULL, /* extract_cond_bb_edges */
3286 NULL /* flush_pending_stmts */
3289 /* Implementation of CFG manipulation for cfg layout RTL, where
3290 basic block connected via fallthru edges does not have to be adjacent.
3291 This representation will hopefully become the default one in future
3292 version of the compiler. */
3294 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3296 rtl_verify_flow_info_1,
3298 cfg_layout_create_basic_block,
3299 cfg_layout_redirect_edge_and_branch,
3300 cfg_layout_redirect_edge_and_branch_force,
3301 rtl_can_remove_branch_p,
3302 cfg_layout_delete_block,
3303 cfg_layout_split_block,
3304 rtl_move_block_after,
3305 cfg_layout_can_merge_blocks_p,
3306 cfg_layout_merge_blocks,
3309 cfg_layout_can_duplicate_bb_p,
3310 cfg_layout_duplicate_bb,
3311 cfg_layout_split_edge,
3312 rtl_make_forwarder_block,
3313 NULL, /* tidy_fallthru_edge */
3314 rtl_force_nonfallthru,
3315 rtl_block_ends_with_call_p,
3316 rtl_block_ends_with_condjump_p,
3317 rtl_flow_call_edges_add,
3318 NULL, /* execute_on_growing_pred */
3319 NULL, /* execute_on_shrinking_pred */
3320 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3321 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3322 NULL, /* lv_adjust_loop_header_phi*/
3323 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3324 NULL /* flush_pending_stmts */