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
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* This file contains low level functions to manipulate the CFG and analyze it
23 that are aware of the RTL intermediate language.
25 Available functionality:
26 - Basic CFG/RTL manipulation API documented in cfghooks.h
27 - CFG-aware instruction chain manipulation
28 delete_insn, delete_insn_chain
29 - Edge splitting and committing to edges
30 insert_insn_on_edge, commit_edge_insertions
31 - CFG updating after insn simplification
32 purge_dead_edges, purge_all_dead_edges
34 Functions not supposed for generic use:
35 - Infrastructure to determine quickly basic block for insn
36 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
37 - Edge redirection with updating and optimizing of insn chain
38 block_label, tidy_fallthru_edge, force_nonfallthru */
42 #include "coretypes.h"
46 #include "hard-reg-set.h"
47 #include "basic-block.h"
56 #include "insn-attr.h"
57 #include "insn-config.h"
58 #include "cfglayout.h"
63 #include "tree-pass.h"
66 static int can_delete_note_p (const_rtx);
67 static int can_delete_label_p (const_rtx);
68 static basic_block rtl_split_edge (edge);
69 static bool rtl_move_block_after (basic_block, basic_block);
70 static int rtl_verify_flow_info (void);
71 static basic_block cfg_layout_split_block (basic_block, void *);
72 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
73 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
74 static void cfg_layout_delete_block (basic_block);
75 static void rtl_delete_block (basic_block);
76 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
77 static edge rtl_redirect_edge_and_branch (edge, basic_block);
78 static basic_block rtl_split_block (basic_block, void *);
79 static void rtl_dump_bb (basic_block, FILE *, int, int);
80 static int rtl_verify_flow_info_1 (void);
81 static void rtl_make_forwarder_block (edge);
83 /* Return true if NOTE is not one of the ones that must be kept paired,
84 so that we may simply delete it. */
87 can_delete_note_p (const_rtx note)
89 switch (NOTE_KIND (note))
91 case NOTE_INSN_DELETED:
92 case NOTE_INSN_BASIC_BLOCK:
93 case NOTE_INSN_EPILOGUE_BEG:
101 /* True if a given label can be deleted. */
104 can_delete_label_p (const_rtx label)
106 return (!LABEL_PRESERVE_P (label)
107 /* User declared labels must be preserved. */
108 && LABEL_NAME (label) == 0
109 && !in_expr_list_p (forced_labels, label));
112 /* Delete INSN by patching it out. Return the next insn. */
115 delete_insn (rtx insn)
117 rtx next = NEXT_INSN (insn);
119 bool really_delete = true;
123 /* Some labels can't be directly removed from the INSN chain, as they
124 might be references via variables, constant pool etc.
125 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
126 if (! can_delete_label_p (insn))
128 const char *name = LABEL_NAME (insn);
130 really_delete = false;
131 PUT_CODE (insn, NOTE);
132 NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL;
133 NOTE_DELETED_LABEL_NAME (insn) = name;
136 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
141 /* If this insn has already been deleted, something is very wrong. */
142 gcc_assert (!INSN_DELETED_P (insn));
144 INSN_DELETED_P (insn) = 1;
147 /* If deleting a jump, decrement the use count of the label. Deleting
148 the label itself should happen in the normal course of block merging. */
151 if (JUMP_LABEL (insn)
152 && LABEL_P (JUMP_LABEL (insn)))
153 LABEL_NUSES (JUMP_LABEL (insn))--;
155 /* If there are more targets, remove them too. */
157 = find_reg_note (insn, REG_LABEL_TARGET, NULL_RTX)) != NULL_RTX
158 && LABEL_P (XEXP (note, 0)))
160 LABEL_NUSES (XEXP (note, 0))--;
161 remove_note (insn, note);
165 /* Also if deleting any insn that references a label as an operand. */
166 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, NULL_RTX)) != NULL_RTX
167 && LABEL_P (XEXP (note, 0)))
169 LABEL_NUSES (XEXP (note, 0))--;
170 remove_note (insn, note);
174 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
175 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
177 rtx pat = PATTERN (insn);
178 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
179 int len = XVECLEN (pat, diff_vec_p);
182 for (i = 0; i < len; i++)
184 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
186 /* When deleting code in bulk (e.g. removing many unreachable
187 blocks) we can delete a label that's a target of the vector
188 before deleting the vector itself. */
190 LABEL_NUSES (label)--;
197 /* Like delete_insn but also purge dead edges from BB. */
200 delete_insn_and_edges (rtx insn)
206 && BLOCK_FOR_INSN (insn)
207 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
209 x = delete_insn (insn);
211 purge_dead_edges (BLOCK_FOR_INSN (insn));
215 /* Unlink a chain of insns between START and FINISH, leaving notes
216 that must be paired. If CLEAR_BB is true, we set bb field for
217 insns that cannot be removed to NULL. */
220 delete_insn_chain (rtx start, rtx finish, bool clear_bb)
224 /* Unchain the insns one by one. It would be quicker to delete all of these
225 with a single unchaining, rather than one at a time, but we need to keep
229 next = NEXT_INSN (start);
230 if (NOTE_P (start) && !can_delete_note_p (start))
233 next = delete_insn (start);
235 if (clear_bb && !INSN_DELETED_P (start))
236 set_block_for_insn (start, NULL);
244 /* Create a new basic block consisting of the instructions between HEAD and END
245 inclusive. This function is designed to allow fast BB construction - reuses
246 the note and basic block struct in BB_NOTE, if any and do not grow
247 BASIC_BLOCK chain and should be used directly only by CFG construction code.
248 END can be NULL in to create new empty basic block before HEAD. Both END
249 and HEAD can be NULL to create basic block at the end of INSN chain.
250 AFTER is the basic block we should be put after. */
253 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
258 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
261 /* If we found an existing note, thread it back onto the chain. */
269 after = PREV_INSN (head);
273 if (after != bb_note && NEXT_INSN (after) != bb_note)
274 reorder_insns_nobb (bb_note, bb_note, after);
278 /* Otherwise we must create a note and a basic block structure. */
282 init_rtl_bb_info (bb);
285 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
286 else if (LABEL_P (head) && end)
288 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
294 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
300 NOTE_BASIC_BLOCK (bb_note) = bb;
303 /* Always include the bb note in the block. */
304 if (NEXT_INSN (end) == bb_note)
309 bb->index = last_basic_block++;
310 bb->flags = BB_NEW | BB_RTL;
311 link_block (bb, after);
312 SET_BASIC_BLOCK (bb->index, bb);
313 df_bb_refs_record (bb->index, false);
314 update_bb_for_insn (bb);
315 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
317 /* Tag the block so that we know it has been used when considering
318 other basic block notes. */
324 /* Create new basic block consisting of instructions in between HEAD and END
325 and place it to the BB chain after block AFTER. END can be NULL in to
326 create new empty basic block before HEAD. Both END and HEAD can be NULL to
327 create basic block at the end of INSN chain. */
330 rtl_create_basic_block (void *headp, void *endp, basic_block after)
332 rtx head = (rtx) headp, end = (rtx) endp;
335 /* Grow the basic block array if needed. */
336 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info))
338 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
339 VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size);
344 bb = create_basic_block_structure (head, end, NULL, after);
350 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
352 basic_block newbb = rtl_create_basic_block (head, end, after);
357 /* Delete the insns in a (non-live) block. We physically delete every
358 non-deleted-note insn, and update the flow graph appropriately.
360 Return nonzero if we deleted an exception handler. */
362 /* ??? Preserving all such notes strikes me as wrong. It would be nice
363 to post-process the stream to remove empty blocks, loops, ranges, etc. */
366 rtl_delete_block (basic_block b)
370 /* If the head of this block is a CODE_LABEL, then it might be the
371 label for an exception handler which can't be reached. We need
372 to remove the label from the exception_handler_label list. */
375 end = get_last_bb_insn (b);
377 /* Selectively delete the entire chain. */
379 delete_insn_chain (insn, end, true);
383 fprintf (dump_file, "deleting block %d\n", b->index);
384 df_bb_delete (b->index);
387 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
390 compute_bb_for_insn (void)
396 rtx end = BB_END (bb);
399 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
401 BLOCK_FOR_INSN (insn) = bb;
408 /* Release the basic_block_for_insn array. */
411 free_bb_for_insn (void)
414 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
415 if (!BARRIER_P (insn))
416 BLOCK_FOR_INSN (insn) = NULL;
421 rest_of_pass_free_cfg (void)
424 /* The resource.c machinery uses DF but the CFG isn't guaranteed to be
425 valid at that point so it would be too late to call df_analyze. */
426 if (optimize > 0 && flag_delayed_branch)
434 struct rtl_opt_pass pass_free_cfg =
440 rest_of_pass_free_cfg, /* execute */
443 0, /* static_pass_number */
445 0, /* properties_required */
446 0, /* properties_provided */
447 PROP_cfg, /* properties_destroyed */
448 0, /* todo_flags_start */
449 0, /* todo_flags_finish */
453 /* Return RTX to emit after when we want to emit code on the entry of function. */
455 entry_of_function (void)
457 return (n_basic_blocks > NUM_FIXED_BLOCKS ?
458 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
461 /* Emit INSN at the entry point of the function, ensuring that it is only
462 executed once per function. */
464 emit_insn_at_entry (rtx insn)
466 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs);
467 edge e = ei_safe_edge (ei);
468 gcc_assert (e->flags & EDGE_FALLTHRU);
470 insert_insn_on_edge (insn, e);
471 commit_edge_insertions ();
474 /* Update BLOCK_FOR_INSN of insns between BEGIN and END
475 (or BARRIER if found) and notify df of the bb change.
476 The insn chain range is inclusive
477 (i.e. both BEGIN and END will be updated. */
480 update_bb_for_insn_chain (rtx begin, rtx end, basic_block bb)
484 end = NEXT_INSN (end);
485 for (insn = begin; insn != end; insn = NEXT_INSN (insn))
486 if (!BARRIER_P (insn))
487 df_insn_change_bb (insn, bb);
490 /* Update BLOCK_FOR_INSN of insns in BB to BB,
491 and notify df of the change. */
494 update_bb_for_insn (basic_block bb)
496 update_bb_for_insn_chain (BB_HEAD (bb), BB_END (bb), bb);
500 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
501 note associated with the BLOCK. */
504 first_insn_after_basic_block_note (basic_block block)
508 /* Get the first instruction in the block. */
509 insn = BB_HEAD (block);
511 if (insn == NULL_RTX)
514 insn = NEXT_INSN (insn);
515 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
517 return NEXT_INSN (insn);
520 /* Creates a new basic block just after basic block B by splitting
521 everything after specified instruction I. */
524 rtl_split_block (basic_block bb, void *insnp)
527 rtx insn = (rtx) insnp;
533 insn = first_insn_after_basic_block_note (bb);
536 insn = PREV_INSN (insn);
538 insn = get_last_insn ();
541 /* We probably should check type of the insn so that we do not create
542 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
544 if (insn == BB_END (bb))
545 emit_note_after (NOTE_INSN_DELETED, insn);
547 /* Create the new basic block. */
548 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
549 BB_COPY_PARTITION (new_bb, bb);
552 /* Redirect the outgoing edges. */
553 new_bb->succs = bb->succs;
555 FOR_EACH_EDGE (e, ei, new_bb->succs)
558 /* The new block starts off being dirty. */
559 df_set_bb_dirty (bb);
563 /* Blocks A and B are to be merged into a single block A. The insns
564 are already contiguous. */
567 rtl_merge_blocks (basic_block a, basic_block b)
569 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
570 rtx del_first = NULL_RTX, del_last = NULL_RTX;
574 fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
576 /* If there was a CODE_LABEL beginning B, delete it. */
577 if (LABEL_P (b_head))
579 /* Detect basic blocks with nothing but a label. This can happen
580 in particular at the end of a function. */
584 del_first = del_last = b_head;
585 b_head = NEXT_INSN (b_head);
588 /* Delete the basic block note and handle blocks containing just that
590 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
598 b_head = NEXT_INSN (b_head);
601 /* If there was a jump out of A, delete it. */
606 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
608 || NOTE_INSN_BASIC_BLOCK_P (prev)
609 || prev == BB_HEAD (a))
615 /* If this was a conditional jump, we need to also delete
616 the insn that set cc0. */
617 if (only_sets_cc0_p (prev))
621 prev = prev_nonnote_insn (prev);
628 a_end = PREV_INSN (del_first);
630 else if (BARRIER_P (NEXT_INSN (a_end)))
631 del_first = NEXT_INSN (a_end);
633 /* Delete everything marked above as well as crap that might be
634 hanging out between the two blocks. */
636 delete_insn_chain (del_first, del_last, true);
638 /* Reassociate the insns of B with A. */
641 update_bb_for_insn_chain (a_end, b_end, a);
646 df_bb_delete (b->index);
651 /* Return true when block A and B can be merged. */
654 rtl_can_merge_blocks (basic_block a, basic_block b)
656 /* If we are partitioning hot/cold basic blocks, we don't want to
657 mess up unconditional or indirect jumps that cross between hot
660 Basic block partitioning may result in some jumps that appear to
661 be optimizable (or blocks that appear to be mergeable), but which really
662 must be left untouched (they are required to make it safely across
663 partition boundaries). See the comments at the top of
664 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
666 if (BB_PARTITION (a) != BB_PARTITION (b))
669 /* There must be exactly one edge in between the blocks. */
670 return (single_succ_p (a)
671 && single_succ (a) == b
674 /* Must be simple edge. */
675 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
677 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
678 /* If the jump insn has side effects,
679 we can't kill the edge. */
680 && (!JUMP_P (BB_END (a))
682 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
685 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
689 block_label (basic_block block)
691 if (block == EXIT_BLOCK_PTR)
694 if (!LABEL_P (BB_HEAD (block)))
696 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
699 return BB_HEAD (block);
702 /* Attempt to perform edge redirection by replacing possibly complex jump
703 instruction by unconditional jump or removing jump completely. This can
704 apply only if all edges now point to the same block. The parameters and
705 return values are equivalent to redirect_edge_and_branch. */
708 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
710 basic_block src = e->src;
711 rtx insn = BB_END (src), kill_from;
715 /* If we are partitioning hot/cold basic blocks, we don't want to
716 mess up unconditional or indirect jumps that cross between hot
719 Basic block partitioning may result in some jumps that appear to
720 be optimizable (or blocks that appear to be mergeable), but which really
721 must be left untouched (they are required to make it safely across
722 partition boundaries). See the comments at the top of
723 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
725 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
726 || BB_PARTITION (src) != BB_PARTITION (target))
729 /* We can replace or remove a complex jump only when we have exactly
730 two edges. Also, if we have exactly one outgoing edge, we can
732 if (EDGE_COUNT (src->succs) >= 3
733 /* Verify that all targets will be TARGET. Specifically, the
734 edge that is not E must also go to TARGET. */
735 || (EDGE_COUNT (src->succs) == 2
736 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
739 if (!onlyjump_p (insn))
741 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
744 /* Avoid removing branch with side effects. */
745 set = single_set (insn);
746 if (!set || side_effects_p (set))
749 /* In case we zap a conditional jump, we'll need to kill
750 the cc0 setter too. */
753 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
754 && only_sets_cc0_p (PREV_INSN (insn)))
755 kill_from = PREV_INSN (insn);
758 /* See if we can create the fallthru edge. */
759 if (in_cfglayout || can_fallthru (src, target))
762 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
765 /* Selectively unlink whole insn chain. */
768 rtx insn = src->il.rtl->footer;
770 delete_insn_chain (kill_from, BB_END (src), false);
772 /* Remove barriers but keep jumptables. */
775 if (BARRIER_P (insn))
777 if (PREV_INSN (insn))
778 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
780 src->il.rtl->footer = NEXT_INSN (insn);
781 if (NEXT_INSN (insn))
782 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
786 insn = NEXT_INSN (insn);
790 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
794 /* If this already is simplejump, redirect it. */
795 else if (simplejump_p (insn))
797 if (e->dest == target)
800 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
801 INSN_UID (insn), e->dest->index, target->index);
802 if (!redirect_jump (insn, block_label (target), 0))
804 gcc_assert (target == EXIT_BLOCK_PTR);
809 /* Cannot do anything for target exit block. */
810 else if (target == EXIT_BLOCK_PTR)
813 /* Or replace possibly complicated jump insn by simple jump insn. */
816 rtx target_label = block_label (target);
817 rtx barrier, label, table;
819 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
820 JUMP_LABEL (BB_END (src)) = target_label;
821 LABEL_NUSES (target_label)++;
823 fprintf (dump_file, "Replacing insn %i by jump %i\n",
824 INSN_UID (insn), INSN_UID (BB_END (src)));
827 delete_insn_chain (kill_from, insn, false);
829 /* Recognize a tablejump that we are converting to a
830 simple jump and remove its associated CODE_LABEL
831 and ADDR_VEC or ADDR_DIFF_VEC. */
832 if (tablejump_p (insn, &label, &table))
833 delete_insn_chain (label, table, false);
835 barrier = next_nonnote_insn (BB_END (src));
836 if (!barrier || !BARRIER_P (barrier))
837 emit_barrier_after (BB_END (src));
840 if (barrier != NEXT_INSN (BB_END (src)))
842 /* Move the jump before barrier so that the notes
843 which originally were or were created before jump table are
844 inside the basic block. */
845 rtx new_insn = BB_END (src);
847 update_bb_for_insn_chain (NEXT_INSN (BB_END (src)),
848 PREV_INSN (barrier), src);
850 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
851 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
853 NEXT_INSN (new_insn) = barrier;
854 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
856 PREV_INSN (new_insn) = PREV_INSN (barrier);
857 PREV_INSN (barrier) = new_insn;
862 /* Keep only one edge out and set proper flags. */
863 if (!single_succ_p (src))
865 gcc_assert (single_succ_p (src));
867 e = single_succ_edge (src);
869 e->flags = EDGE_FALLTHRU;
873 e->probability = REG_BR_PROB_BASE;
874 e->count = src->count;
876 if (e->dest != target)
877 redirect_edge_succ (e, target);
881 /* Subroutine of redirect_branch_edge that tries to patch the jump
882 instruction INSN so that it reaches block NEW. Do this
883 only when it originally reached block OLD. Return true if this
884 worked or the original target wasn't OLD, return false if redirection
888 patch_jump_insn (rtx insn, rtx old_label, basic_block new_bb)
891 /* Recognize a tablejump and adjust all matching cases. */
892 if (tablejump_p (insn, NULL, &tmp))
896 rtx new_label = block_label (new_bb);
898 if (new_bb == EXIT_BLOCK_PTR)
900 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
901 vec = XVEC (PATTERN (tmp), 0);
903 vec = XVEC (PATTERN (tmp), 1);
905 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
906 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
908 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
909 --LABEL_NUSES (old_label);
910 ++LABEL_NUSES (new_label);
913 /* Handle casesi dispatch insns. */
914 if ((tmp = single_set (insn)) != NULL
915 && SET_DEST (tmp) == pc_rtx
916 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
917 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
918 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
920 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
922 --LABEL_NUSES (old_label);
923 ++LABEL_NUSES (new_label);
928 /* ?? We may play the games with moving the named labels from
929 one basic block to the other in case only one computed_jump is
931 if (computed_jump_p (insn)
932 /* A return instruction can't be redirected. */
933 || returnjump_p (insn))
936 if (!currently_expanding_to_rtl || JUMP_LABEL (insn) == old_label)
938 /* If the insn doesn't go where we think, we're confused. */
939 gcc_assert (JUMP_LABEL (insn) == old_label);
941 /* If the substitution doesn't succeed, die. This can happen
942 if the back end emitted unrecognizable instructions or if
943 target is exit block on some arches. */
944 if (!redirect_jump (insn, block_label (new_bb), 0))
946 gcc_assert (new_bb == EXIT_BLOCK_PTR);
955 /* Redirect edge representing branch of (un)conditional jump or tablejump,
958 redirect_branch_edge (edge e, basic_block target)
960 rtx old_label = BB_HEAD (e->dest);
961 basic_block src = e->src;
962 rtx insn = BB_END (src);
964 /* We can only redirect non-fallthru edges of jump insn. */
965 if (e->flags & EDGE_FALLTHRU)
967 else if (!JUMP_P (insn) && !currently_expanding_to_rtl)
970 if (!currently_expanding_to_rtl)
972 if (!patch_jump_insn (insn, old_label, target))
976 /* When expanding this BB might actually contain multiple
977 jumps (i.e. not yet split by find_many_sub_basic_blocks).
978 Redirect all of those that match our label. */
979 for (insn = BB_HEAD (src); insn != NEXT_INSN (BB_END (src));
980 insn = NEXT_INSN (insn))
981 if (JUMP_P (insn) && !patch_jump_insn (insn, old_label, target))
985 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
986 e->src->index, e->dest->index, target->index);
988 if (e->dest != target)
989 e = redirect_edge_succ_nodup (e, target);
994 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
995 expense of adding new instructions or reordering basic blocks.
997 Function can be also called with edge destination equivalent to the TARGET.
998 Then it should try the simplifications and do nothing if none is possible.
1000 Return edge representing the branch if transformation succeeded. Return NULL
1002 We still return NULL in case E already destinated TARGET and we didn't
1003 managed to simplify instruction stream. */
1006 rtl_redirect_edge_and_branch (edge e, basic_block target)
1009 basic_block src = e->src;
1011 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
1014 if (e->dest == target)
1017 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
1019 df_set_bb_dirty (src);
1023 ret = redirect_branch_edge (e, target);
1027 df_set_bb_dirty (src);
1031 /* Like force_nonfallthru below, but additionally performs redirection
1032 Used by redirect_edge_and_branch_force. */
1035 force_nonfallthru_and_redirect (edge e, basic_block target)
1037 basic_block jump_block, new_bb = NULL, src = e->src;
1040 int abnormal_edge_flags = 0;
1043 /* In the case the last instruction is conditional jump to the next
1044 instruction, first redirect the jump itself and then continue
1045 by creating a basic block afterwards to redirect fallthru edge. */
1046 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1047 && any_condjump_p (BB_END (e->src))
1048 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1051 edge b = unchecked_make_edge (e->src, target, 0);
1054 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1055 gcc_assert (redirected);
1057 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1060 int prob = INTVAL (XEXP (note, 0));
1062 b->probability = prob;
1063 b->count = e->count * prob / REG_BR_PROB_BASE;
1064 e->probability -= e->probability;
1065 e->count -= b->count;
1066 if (e->probability < 0)
1073 if (e->flags & EDGE_ABNORMAL)
1075 /* Irritating special case - fallthru edge to the same block as abnormal
1077 We can't redirect abnormal edge, but we still can split the fallthru
1078 one and create separate abnormal edge to original destination.
1079 This allows bb-reorder to make such edge non-fallthru. */
1080 gcc_assert (e->dest == target);
1081 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1082 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1086 gcc_assert (e->flags & EDGE_FALLTHRU);
1087 if (e->src == ENTRY_BLOCK_PTR)
1089 /* We can't redirect the entry block. Create an empty block
1090 at the start of the function which we use to add the new
1096 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1098 /* Change the existing edge's source to be the new block, and add
1099 a new edge from the entry block to the new block. */
1101 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1105 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1115 VEC_safe_push (edge, gc, bb->succs, e);
1116 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1120 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1122 /* Create the new structures. */
1124 /* If the old block ended with a tablejump, skip its table
1125 by searching forward from there. Otherwise start searching
1126 forward from the last instruction of the old block. */
1127 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1128 note = BB_END (e->src);
1129 note = NEXT_INSN (note);
1131 jump_block = create_basic_block (note, NULL, e->src);
1132 jump_block->count = e->count;
1133 jump_block->frequency = EDGE_FREQUENCY (e);
1134 jump_block->loop_depth = target->loop_depth;
1136 /* Make sure new block ends up in correct hot/cold section. */
1138 BB_COPY_PARTITION (jump_block, e->src);
1139 if (flag_reorder_blocks_and_partition
1140 && targetm.have_named_sections
1141 && JUMP_P (BB_END (jump_block))
1142 && !any_condjump_p (BB_END (jump_block))
1143 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1144 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX);
1147 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1148 new_edge->probability = e->probability;
1149 new_edge->count = e->count;
1151 /* Redirect old edge. */
1152 redirect_edge_pred (e, jump_block);
1153 e->probability = REG_BR_PROB_BASE;
1155 new_bb = jump_block;
1158 jump_block = e->src;
1160 if (e->goto_locus && e->goto_block == NULL)
1161 loc = e->goto_locus;
1164 e->flags &= ~EDGE_FALLTHRU;
1165 if (target == EXIT_BLOCK_PTR)
1168 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc);
1175 rtx label = block_label (target);
1176 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc);
1177 JUMP_LABEL (BB_END (jump_block)) = label;
1178 LABEL_NUSES (label)++;
1181 emit_barrier_after (BB_END (jump_block));
1182 redirect_edge_succ_nodup (e, target);
1184 if (abnormal_edge_flags)
1185 make_edge (src, target, abnormal_edge_flags);
1187 df_mark_solutions_dirty ();
1191 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1192 (and possibly create new basic block) to make edge non-fallthru.
1193 Return newly created BB or NULL if none. */
1196 force_nonfallthru (edge e)
1198 return force_nonfallthru_and_redirect (e, e->dest);
1201 /* Redirect edge even at the expense of creating new jump insn or
1202 basic block. Return new basic block if created, NULL otherwise.
1203 Conversion must be possible. */
1206 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1208 if (redirect_edge_and_branch (e, target)
1209 || e->dest == target)
1212 /* In case the edge redirection failed, try to force it to be non-fallthru
1213 and redirect newly created simplejump. */
1214 df_set_bb_dirty (e->src);
1215 return force_nonfallthru_and_redirect (e, target);
1218 /* The given edge should potentially be a fallthru edge. If that is in
1219 fact true, delete the jump and barriers that are in the way. */
1222 rtl_tidy_fallthru_edge (edge e)
1225 basic_block b = e->src, c = b->next_bb;
1227 /* ??? In a late-running flow pass, other folks may have deleted basic
1228 blocks by nopping out blocks, leaving multiple BARRIERs between here
1229 and the target label. They ought to be chastised and fixed.
1231 We can also wind up with a sequence of undeletable labels between
1232 one block and the next.
1234 So search through a sequence of barriers, labels, and notes for
1235 the head of block C and assert that we really do fall through. */
1237 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1241 /* Remove what will soon cease being the jump insn from the source block.
1242 If block B consisted only of this single jump, turn it into a deleted
1247 && (any_uncondjump_p (q)
1248 || single_succ_p (b)))
1251 /* If this was a conditional jump, we need to also delete
1252 the insn that set cc0. */
1253 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1260 /* Selectively unlink the sequence. */
1261 if (q != PREV_INSN (BB_HEAD (c)))
1262 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false);
1264 e->flags |= EDGE_FALLTHRU;
1267 /* Should move basic block BB after basic block AFTER. NIY. */
1270 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1271 basic_block after ATTRIBUTE_UNUSED)
1276 /* Split a (typically critical) edge. Return the new block.
1277 The edge must not be abnormal.
1279 ??? The code generally expects to be called on critical edges.
1280 The case of a block ending in an unconditional jump to a
1281 block with multiple predecessors is not handled optimally. */
1284 rtl_split_edge (edge edge_in)
1289 /* Abnormal edges cannot be split. */
1290 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1292 /* We are going to place the new block in front of edge destination.
1293 Avoid existence of fallthru predecessors. */
1294 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1299 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1300 if (e->flags & EDGE_FALLTHRU)
1304 force_nonfallthru (e);
1307 /* Create the basic block note. */
1308 if (edge_in->dest != EXIT_BLOCK_PTR)
1309 before = BB_HEAD (edge_in->dest);
1313 /* If this is a fall through edge to the exit block, the blocks might be
1314 not adjacent, and the right place is the after the source. */
1315 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1317 before = NEXT_INSN (BB_END (edge_in->src));
1318 bb = create_basic_block (before, NULL, edge_in->src);
1319 BB_COPY_PARTITION (bb, edge_in->src);
1323 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1324 /* ??? Why not edge_in->dest->prev_bb here? */
1325 BB_COPY_PARTITION (bb, edge_in->dest);
1328 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1330 /* For non-fallthru edges, we must adjust the predecessor's
1331 jump instruction to target our new block. */
1332 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1334 edge redirected = redirect_edge_and_branch (edge_in, bb);
1335 gcc_assert (redirected);
1338 redirect_edge_succ (edge_in, bb);
1343 /* Queue instructions for insertion on an edge between two basic blocks.
1344 The new instructions and basic blocks (if any) will not appear in the
1345 CFG until commit_edge_insertions is called. */
1348 insert_insn_on_edge (rtx pattern, edge e)
1350 /* We cannot insert instructions on an abnormal critical edge.
1351 It will be easier to find the culprit if we die now. */
1352 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1354 if (e->insns.r == NULL_RTX)
1357 push_to_sequence (e->insns.r);
1359 emit_insn (pattern);
1361 e->insns.r = get_insns ();
1365 /* Update the CFG for the instructions queued on edge E. */
1368 commit_one_edge_insertion (edge e)
1370 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1371 basic_block bb = NULL;
1373 /* Pull the insns off the edge now since the edge might go away. */
1375 e->insns.r = NULL_RTX;
1377 if (!before && !after)
1379 /* Figure out where to put these things. If the destination has
1380 one predecessor, insert there. Except for the exit block. */
1381 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1385 /* Get the location correct wrt a code label, and "nice" wrt
1386 a basic block note, and before everything else. */
1389 tmp = NEXT_INSN (tmp);
1390 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1391 tmp = NEXT_INSN (tmp);
1392 if (tmp == BB_HEAD (bb))
1395 after = PREV_INSN (tmp);
1397 after = get_last_insn ();
1400 /* If the source has one successor and the edge is not abnormal,
1401 insert there. Except for the entry block. */
1402 else if ((e->flags & EDGE_ABNORMAL) == 0
1403 && single_succ_p (e->src)
1404 && e->src != ENTRY_BLOCK_PTR)
1408 /* It is possible to have a non-simple jump here. Consider a target
1409 where some forms of unconditional jumps clobber a register. This
1410 happens on the fr30 for example.
1412 We know this block has a single successor, so we can just emit
1413 the queued insns before the jump. */
1414 if (JUMP_P (BB_END (bb)))
1415 before = BB_END (bb);
1418 /* We'd better be fallthru, or we've lost track of
1420 gcc_assert (e->flags & EDGE_FALLTHRU);
1422 after = BB_END (bb);
1425 /* Otherwise we must split the edge. */
1428 bb = split_edge (e);
1429 after = BB_END (bb);
1431 if (flag_reorder_blocks_and_partition
1432 && targetm.have_named_sections
1433 && e->src != ENTRY_BLOCK_PTR
1434 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1435 && !(e->flags & EDGE_CROSSING))
1437 rtx bb_note, cur_insn;
1440 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1441 cur_insn = NEXT_INSN (cur_insn))
1442 if (NOTE_INSN_BASIC_BLOCK_P (cur_insn))
1448 if (JUMP_P (BB_END (bb))
1449 && !any_condjump_p (BB_END (bb))
1450 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1451 add_reg_note (BB_END (bb), REG_CROSSING_JUMP, NULL_RTX);
1456 /* Now that we've found the spot, do the insertion. */
1460 emit_insn_before_noloc (insns, before, bb);
1461 last = prev_nonnote_insn (before);
1464 last = emit_insn_after_noloc (insns, after, bb);
1466 if (returnjump_p (last))
1468 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1469 This is not currently a problem because this only happens
1470 for the (single) epilogue, which already has a fallthru edge
1473 e = single_succ_edge (bb);
1474 gcc_assert (e->dest == EXIT_BLOCK_PTR
1475 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1477 e->flags &= ~EDGE_FALLTHRU;
1478 emit_barrier_after (last);
1481 delete_insn (before);
1484 gcc_assert (!JUMP_P (last));
1486 /* Mark the basic block for find_many_sub_basic_blocks. */
1487 if (current_ir_type () != IR_RTL_CFGLAYOUT)
1491 /* Update the CFG for all queued instructions. */
1494 commit_edge_insertions (void)
1498 bool changed = false;
1500 #ifdef ENABLE_CHECKING
1501 verify_flow_info ();
1504 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1509 FOR_EACH_EDGE (e, ei, bb->succs)
1513 commit_one_edge_insertion (e);
1520 /* In the old rtl CFG API, it was OK to insert control flow on an
1521 edge, apparently? In cfglayout mode, this will *not* work, and
1522 the caller is responsible for making sure that control flow is
1523 valid at all times. */
1524 if (current_ir_type () == IR_RTL_CFGLAYOUT)
1527 blocks = sbitmap_alloc (last_basic_block);
1528 sbitmap_zero (blocks);
1532 SET_BIT (blocks, bb->index);
1533 /* Check for forgotten bb->aux values before commit_edge_insertions
1535 gcc_assert (bb->aux == &bb->aux);
1538 find_many_sub_basic_blocks (blocks);
1539 sbitmap_free (blocks);
1543 /* Print out RTL-specific basic block information (live information
1544 at start and end). */
1547 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED)
1553 s_indent = (char *) alloca ((size_t) indent + 1);
1554 memset (s_indent, ' ', (size_t) indent);
1555 s_indent[indent] = '\0';
1559 df_dump_top (bb, outf);
1563 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1564 insn = NEXT_INSN (insn))
1565 print_rtl_single (outf, insn);
1569 df_dump_bottom (bb, outf);
1575 /* Like print_rtl, but also print out live information for the start of each
1579 print_rtl_with_bb (FILE *outf, const_rtx rtx_first)
1583 fprintf (outf, "(nil)\n");
1586 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1587 int max_uid = get_max_uid ();
1588 basic_block *start = XCNEWVEC (basic_block, max_uid);
1589 basic_block *end = XCNEWVEC (basic_block, max_uid);
1590 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1595 df_dump_start (outf);
1597 FOR_EACH_BB_REVERSE (bb)
1601 start[INSN_UID (BB_HEAD (bb))] = bb;
1602 end[INSN_UID (BB_END (bb))] = bb;
1603 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1605 enum bb_state state = IN_MULTIPLE_BB;
1607 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1609 in_bb_p[INSN_UID (x)] = state;
1611 if (x == BB_END (bb))
1616 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1619 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1624 fprintf (outf, ";; Start of basic block (");
1625 FOR_EACH_EDGE (e, ei, bb->preds)
1626 fprintf (outf, " %d", e->src->index);
1627 fprintf (outf, ") -> %d\n", bb->index);
1631 df_dump_top (bb, outf);
1634 FOR_EACH_EDGE (e, ei, bb->preds)
1636 fputs (";; Pred edge ", outf);
1637 dump_edge_info (outf, e, 0);
1642 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1643 && !NOTE_P (tmp_rtx)
1644 && !BARRIER_P (tmp_rtx))
1645 fprintf (outf, ";; Insn is not within a basic block\n");
1646 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1647 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1649 did_output = print_rtl_single (outf, tmp_rtx);
1651 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1656 fprintf (outf, ";; End of basic block %d -> (", bb->index);
1657 FOR_EACH_EDGE (e, ei, bb->succs)
1658 fprintf (outf, " %d", e->dest->index);
1659 fprintf (outf, ")\n");
1663 df_dump_bottom (bb, outf);
1667 FOR_EACH_EDGE (e, ei, bb->succs)
1669 fputs (";; Succ edge ", outf);
1670 dump_edge_info (outf, e, 1);
1683 if (crtl->epilogue_delay_list != 0)
1685 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1686 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0;
1687 tmp_rtx = XEXP (tmp_rtx, 1))
1688 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1693 update_br_prob_note (basic_block bb)
1696 if (!JUMP_P (BB_END (bb)))
1698 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1699 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1701 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1704 /* Get the last insn associated with block BB (that includes barriers and
1705 tablejumps after BB). */
1707 get_last_bb_insn (basic_block bb)
1710 rtx end = BB_END (bb);
1712 /* Include any jump table following the basic block. */
1713 if (tablejump_p (end, NULL, &tmp))
1716 /* Include any barriers that may follow the basic block. */
1717 tmp = next_nonnote_insn (end);
1718 while (tmp && BARRIER_P (tmp))
1721 tmp = next_nonnote_insn (end);
1727 /* Verify the CFG and RTL consistency common for both underlying RTL and
1730 Currently it does following checks:
1732 - overlapping of basic blocks
1733 - insns with wrong BLOCK_FOR_INSN pointers
1734 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1735 - tails of basic blocks (ensure that boundary is necessary)
1736 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1737 and NOTE_INSN_BASIC_BLOCK
1738 - verify that no fall_thru edge crosses hot/cold partition boundaries
1739 - verify that there are no pending RTL branch predictions
1741 In future it can be extended check a lot of other stuff as well
1742 (reachability of basic blocks, life information, etc. etc.). */
1745 rtl_verify_flow_info_1 (void)
1751 /* Check the general integrity of the basic blocks. */
1752 FOR_EACH_BB_REVERSE (bb)
1756 if (!(bb->flags & BB_RTL))
1758 error ("BB_RTL flag not set for block %d", bb->index);
1762 FOR_BB_INSNS (bb, insn)
1763 if (BLOCK_FOR_INSN (insn) != bb)
1765 error ("insn %d basic block pointer is %d, should be %d",
1767 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1772 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1773 if (!BARRIER_P (insn)
1774 && BLOCK_FOR_INSN (insn) != NULL)
1776 error ("insn %d in header of bb %d has non-NULL basic block",
1777 INSN_UID (insn), bb->index);
1780 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1781 if (!BARRIER_P (insn)
1782 && BLOCK_FOR_INSN (insn) != NULL)
1784 error ("insn %d in footer of bb %d has non-NULL basic block",
1785 INSN_UID (insn), bb->index);
1790 /* Now check the basic blocks (boundaries etc.) */
1791 FOR_EACH_BB_REVERSE (bb)
1793 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1794 edge e, fallthru = NULL;
1798 if (JUMP_P (BB_END (bb))
1799 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1800 && EDGE_COUNT (bb->succs) >= 2
1801 && any_condjump_p (BB_END (bb)))
1803 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1804 && profile_status != PROFILE_ABSENT)
1806 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1807 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1811 FOR_EACH_EDGE (e, ei, bb->succs)
1813 if (e->flags & EDGE_FALLTHRU)
1815 n_fallthru++, fallthru = e;
1816 if ((e->flags & EDGE_CROSSING)
1817 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1818 && e->src != ENTRY_BLOCK_PTR
1819 && e->dest != EXIT_BLOCK_PTR))
1821 error ("fallthru edge crosses section boundary (bb %i)",
1827 if ((e->flags & ~(EDGE_DFS_BACK
1829 | EDGE_IRREDUCIBLE_LOOP
1831 | EDGE_CROSSING)) == 0)
1834 if (e->flags & EDGE_ABNORMAL_CALL)
1837 if (e->flags & EDGE_EH)
1839 else if (e->flags & EDGE_ABNORMAL)
1843 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
1844 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1846 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1850 && (!JUMP_P (BB_END (bb))
1851 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1852 || any_condjump_p (BB_END (bb))))))
1854 error ("too many outgoing branch edges from bb %i", bb->index);
1857 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1859 error ("fallthru edge after unconditional jump %i", bb->index);
1862 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1864 error ("wrong amount of branch edges after unconditional jump %i", bb->index);
1867 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1868 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1870 error ("wrong amount of branch edges after conditional jump %i",
1874 if (n_call && !CALL_P (BB_END (bb)))
1876 error ("call edges for non-call insn in bb %i", bb->index);
1880 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1881 && (!JUMP_P (BB_END (bb))
1882 || any_condjump_p (BB_END (bb))
1883 || any_uncondjump_p (BB_END (bb))))
1885 error ("abnormal edges for no purpose in bb %i", bb->index);
1889 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1890 /* We may have a barrier inside a basic block before dead code
1891 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1892 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1895 if (! BLOCK_FOR_INSN (x))
1897 ("insn %d inside basic block %d but block_for_insn is NULL",
1898 INSN_UID (x), bb->index);
1901 ("insn %d inside basic block %d but block_for_insn is %i",
1902 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1907 /* OK pointers are correct. Now check the header of basic
1908 block. It ought to contain optional CODE_LABEL followed
1909 by NOTE_BASIC_BLOCK. */
1913 if (BB_END (bb) == x)
1915 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1923 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1925 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1930 if (BB_END (bb) == x)
1931 /* Do checks for empty blocks here. */
1934 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1936 if (NOTE_INSN_BASIC_BLOCK_P (x))
1938 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1939 INSN_UID (x), bb->index);
1943 if (x == BB_END (bb))
1946 if (control_flow_insn_p (x))
1948 error ("in basic block %d:", bb->index);
1949 fatal_insn ("flow control insn inside a basic block", x);
1958 /* Verify the CFG and RTL consistency common for both underlying RTL and
1961 Currently it does following checks:
1962 - all checks of rtl_verify_flow_info_1
1963 - test head/end pointers
1964 - check that all insns are in the basic blocks
1965 (except the switch handling code, barriers and notes)
1966 - check that all returns are followed by barriers
1967 - check that all fallthru edge points to the adjacent blocks. */
1970 rtl_verify_flow_info (void)
1973 int err = rtl_verify_flow_info_1 ();
1975 rtx last_head = get_last_insn ();
1976 basic_block *bb_info;
1978 const rtx rtx_first = get_insns ();
1979 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
1980 const int max_uid = get_max_uid ();
1982 bb_info = XCNEWVEC (basic_block, max_uid);
1984 FOR_EACH_BB_REVERSE (bb)
1988 rtx head = BB_HEAD (bb);
1989 rtx end = BB_END (bb);
1991 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1993 /* Verify the end of the basic block is in the INSN chain. */
1997 /* And that the code outside of basic blocks has NULL bb field. */
1999 && BLOCK_FOR_INSN (x) != NULL)
2001 error ("insn %d outside of basic blocks has non-NULL bb field",
2009 error ("end insn %d for block %d not found in the insn stream",
2010 INSN_UID (end), bb->index);
2014 /* Work backwards from the end to the head of the basic block
2015 to verify the head is in the RTL chain. */
2016 for (; x != NULL_RTX; x = PREV_INSN (x))
2018 /* While walking over the insn chain, verify insns appear
2019 in only one basic block. */
2020 if (bb_info[INSN_UID (x)] != NULL)
2022 error ("insn %d is in multiple basic blocks (%d and %d)",
2023 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
2027 bb_info[INSN_UID (x)] = bb;
2034 error ("head insn %d for block %d not found in the insn stream",
2035 INSN_UID (head), bb->index);
2039 last_head = PREV_INSN (x);
2041 FOR_EACH_EDGE (e, ei, bb->succs)
2042 if (e->flags & EDGE_FALLTHRU)
2048 /* Ensure existence of barrier in BB with no fallthru edges. */
2049 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2050 insn = NEXT_INSN (insn))
2052 || NOTE_INSN_BASIC_BLOCK_P (insn))
2054 error ("missing barrier after block %i", bb->index);
2059 else if (e->src != ENTRY_BLOCK_PTR
2060 && e->dest != EXIT_BLOCK_PTR)
2064 if (e->src->next_bb != e->dest)
2067 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2068 e->src->index, e->dest->index);
2072 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2073 insn = NEXT_INSN (insn))
2074 if (BARRIER_P (insn) || INSN_P (insn))
2076 error ("verify_flow_info: Incorrect fallthru %i->%i",
2077 e->src->index, e->dest->index);
2078 fatal_insn ("wrong insn in the fallthru edge", insn);
2084 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2086 /* Check that the code before the first basic block has NULL
2089 && BLOCK_FOR_INSN (x) != NULL)
2091 error ("insn %d outside of basic blocks has non-NULL bb field",
2099 last_bb_seen = ENTRY_BLOCK_PTR;
2101 for (x = rtx_first; x; x = NEXT_INSN (x))
2103 if (NOTE_INSN_BASIC_BLOCK_P (x))
2105 bb = NOTE_BASIC_BLOCK (x);
2108 if (bb != last_bb_seen->next_bb)
2109 internal_error ("basic blocks not laid down consecutively");
2111 curr_bb = last_bb_seen = bb;
2116 switch (GET_CODE (x))
2123 /* An addr_vec is placed outside any basic block. */
2125 && JUMP_P (NEXT_INSN (x))
2126 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2127 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2130 /* But in any case, non-deletable labels can appear anywhere. */
2134 fatal_insn ("insn outside basic block", x);
2139 && returnjump_p (x) && ! condjump_p (x)
2140 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2141 fatal_insn ("return not followed by barrier", x);
2142 if (curr_bb && x == BB_END (curr_bb))
2146 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2148 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2149 num_bb_notes, n_basic_blocks);
2154 /* Assume that the preceding pass has possibly eliminated jump instructions
2155 or converted the unconditional jumps. Eliminate the edges from CFG.
2156 Return true if any edges are eliminated. */
2159 purge_dead_edges (basic_block bb)
2162 rtx insn = BB_END (bb), note;
2163 bool purged = false;
2167 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2168 if (NONJUMP_INSN_P (insn)
2169 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2173 if (! may_trap_p (PATTERN (insn))
2174 || ((eqnote = find_reg_equal_equiv_note (insn))
2175 && ! may_trap_p (XEXP (eqnote, 0))))
2176 remove_note (insn, note);
2179 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2180 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2182 /* There are three types of edges we need to handle correctly here: EH
2183 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2184 latter can appear when nonlocal gotos are used. */
2185 if (e->flags & EDGE_EH)
2187 if (can_throw_internal (BB_END (bb))
2188 /* If this is a call edge, verify that this is a call insn. */
2189 && (! (e->flags & EDGE_ABNORMAL_CALL)
2190 || CALL_P (BB_END (bb))))
2196 else if (e->flags & EDGE_ABNORMAL_CALL)
2198 if (CALL_P (BB_END (bb))
2199 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2200 || INTVAL (XEXP (note, 0)) >= 0))
2213 df_set_bb_dirty (bb);
2223 /* We do care only about conditional jumps and simplejumps. */
2224 if (!any_condjump_p (insn)
2225 && !returnjump_p (insn)
2226 && !simplejump_p (insn))
2229 /* Branch probability/prediction notes are defined only for
2230 condjumps. We've possibly turned condjump into simplejump. */
2231 if (simplejump_p (insn))
2233 note = find_reg_note (insn, REG_BR_PROB, NULL);
2235 remove_note (insn, note);
2236 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2237 remove_note (insn, note);
2240 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2242 /* Avoid abnormal flags to leak from computed jumps turned
2243 into simplejumps. */
2245 e->flags &= ~EDGE_ABNORMAL;
2247 /* See if this edge is one we should keep. */
2248 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2249 /* A conditional jump can fall through into the next
2250 block, so we should keep the edge. */
2255 else if (e->dest != EXIT_BLOCK_PTR
2256 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2257 /* If the destination block is the target of the jump,
2263 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2264 /* If the destination block is the exit block, and this
2265 instruction is a return, then keep the edge. */
2270 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2271 /* Keep the edges that correspond to exceptions thrown by
2272 this instruction and rematerialize the EDGE_ABNORMAL
2273 flag we just cleared above. */
2275 e->flags |= EDGE_ABNORMAL;
2280 /* We do not need this edge. */
2281 df_set_bb_dirty (bb);
2286 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2290 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2295 /* Redistribute probabilities. */
2296 if (single_succ_p (bb))
2298 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2299 single_succ_edge (bb)->count = bb->count;
2303 note = find_reg_note (insn, REG_BR_PROB, NULL);
2307 b = BRANCH_EDGE (bb);
2308 f = FALLTHRU_EDGE (bb);
2309 b->probability = INTVAL (XEXP (note, 0));
2310 f->probability = REG_BR_PROB_BASE - b->probability;
2311 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2312 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2317 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2319 /* First, there should not be any EH or ABCALL edges resulting
2320 from non-local gotos and the like. If there were, we shouldn't
2321 have created the sibcall in the first place. Second, there
2322 should of course never have been a fallthru edge. */
2323 gcc_assert (single_succ_p (bb));
2324 gcc_assert (single_succ_edge (bb)->flags
2325 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2330 /* If we don't see a jump insn, we don't know exactly why the block would
2331 have been broken at this point. Look for a simple, non-fallthru edge,
2332 as these are only created by conditional branches. If we find such an
2333 edge we know that there used to be a jump here and can then safely
2334 remove all non-fallthru edges. */
2336 FOR_EACH_EDGE (e, ei, bb->succs)
2337 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2346 /* Remove all but the fake and fallthru edges. The fake edge may be
2347 the only successor for this block in the case of noreturn
2349 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2351 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2353 df_set_bb_dirty (bb);
2361 gcc_assert (single_succ_p (bb));
2363 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2364 single_succ_edge (bb)->count = bb->count;
2367 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2372 /* Search all basic blocks for potentially dead edges and purge them. Return
2373 true if some edge has been eliminated. */
2376 purge_all_dead_edges (void)
2383 bool purged_here = purge_dead_edges (bb);
2385 purged |= purged_here;
2391 /* Same as split_block but update cfg_layout structures. */
2394 cfg_layout_split_block (basic_block bb, void *insnp)
2396 rtx insn = (rtx) insnp;
2397 basic_block new_bb = rtl_split_block (bb, insn);
2399 new_bb->il.rtl->footer = bb->il.rtl->footer;
2400 bb->il.rtl->footer = NULL;
2405 /* Redirect Edge to DEST. */
2407 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2409 basic_block src = e->src;
2412 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2415 if (e->dest == dest)
2418 if (e->src != ENTRY_BLOCK_PTR
2419 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2421 df_set_bb_dirty (src);
2425 if (e->src == ENTRY_BLOCK_PTR
2426 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2429 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2430 e->src->index, dest->index);
2432 df_set_bb_dirty (e->src);
2433 redirect_edge_succ (e, dest);
2437 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2438 in the case the basic block appears to be in sequence. Avoid this
2441 if (e->flags & EDGE_FALLTHRU)
2443 /* Redirect any branch edges unified with the fallthru one. */
2444 if (JUMP_P (BB_END (src))
2445 && label_is_jump_target_p (BB_HEAD (e->dest),
2451 fprintf (dump_file, "Fallthru edge unified with branch "
2452 "%i->%i redirected to %i\n",
2453 e->src->index, e->dest->index, dest->index);
2454 e->flags &= ~EDGE_FALLTHRU;
2455 redirected = redirect_branch_edge (e, dest);
2456 gcc_assert (redirected);
2457 e->flags |= EDGE_FALLTHRU;
2458 df_set_bb_dirty (e->src);
2461 /* In case we are redirecting fallthru edge to the branch edge
2462 of conditional jump, remove it. */
2463 if (EDGE_COUNT (src->succs) == 2)
2465 /* Find the edge that is different from E. */
2466 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2469 && any_condjump_p (BB_END (src))
2470 && onlyjump_p (BB_END (src)))
2471 delete_insn (BB_END (src));
2473 ret = redirect_edge_succ_nodup (e, dest);
2475 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2476 e->src->index, e->dest->index, dest->index);
2479 ret = redirect_branch_edge (e, dest);
2481 /* We don't want simplejumps in the insn stream during cfglayout. */
2482 gcc_assert (!simplejump_p (BB_END (src)));
2484 df_set_bb_dirty (src);
2488 /* Simple wrapper as we always can redirect fallthru edges. */
2490 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2492 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2494 gcc_assert (redirected);
2498 /* Same as delete_basic_block but update cfg_layout structures. */
2501 cfg_layout_delete_block (basic_block bb)
2503 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2505 if (bb->il.rtl->header)
2507 next = BB_HEAD (bb);
2509 NEXT_INSN (prev) = bb->il.rtl->header;
2511 set_first_insn (bb->il.rtl->header);
2512 PREV_INSN (bb->il.rtl->header) = prev;
2513 insn = bb->il.rtl->header;
2514 while (NEXT_INSN (insn))
2515 insn = NEXT_INSN (insn);
2516 NEXT_INSN (insn) = next;
2517 PREV_INSN (next) = insn;
2519 next = NEXT_INSN (BB_END (bb));
2520 if (bb->il.rtl->footer)
2522 insn = bb->il.rtl->footer;
2525 if (BARRIER_P (insn))
2527 if (PREV_INSN (insn))
2528 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2530 bb->il.rtl->footer = NEXT_INSN (insn);
2531 if (NEXT_INSN (insn))
2532 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2536 insn = NEXT_INSN (insn);
2538 if (bb->il.rtl->footer)
2541 NEXT_INSN (insn) = bb->il.rtl->footer;
2542 PREV_INSN (bb->il.rtl->footer) = insn;
2543 while (NEXT_INSN (insn))
2544 insn = NEXT_INSN (insn);
2545 NEXT_INSN (insn) = next;
2547 PREV_INSN (next) = insn;
2549 set_last_insn (insn);
2552 if (bb->next_bb != EXIT_BLOCK_PTR)
2553 to = &bb->next_bb->il.rtl->header;
2555 to = &cfg_layout_function_footer;
2557 rtl_delete_block (bb);
2560 prev = NEXT_INSN (prev);
2562 prev = get_insns ();
2564 next = PREV_INSN (next);
2566 next = get_last_insn ();
2568 if (next && NEXT_INSN (next) != prev)
2570 remaints = unlink_insn_chain (prev, next);
2572 while (NEXT_INSN (insn))
2573 insn = NEXT_INSN (insn);
2574 NEXT_INSN (insn) = *to;
2576 PREV_INSN (*to) = insn;
2581 /* Return true when blocks A and B can be safely merged. */
2584 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2586 /* If we are partitioning hot/cold basic blocks, we don't want to
2587 mess up unconditional or indirect jumps that cross between hot
2590 Basic block partitioning may result in some jumps that appear to
2591 be optimizable (or blocks that appear to be mergeable), but which really
2592 must be left untouched (they are required to make it safely across
2593 partition boundaries). See the comments at the top of
2594 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2596 if (BB_PARTITION (a) != BB_PARTITION (b))
2599 /* There must be exactly one edge in between the blocks. */
2600 return (single_succ_p (a)
2601 && single_succ (a) == b
2602 && single_pred_p (b) == 1
2604 /* Must be simple edge. */
2605 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2606 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2607 /* If the jump insn has side effects, we can't kill the edge.
2608 When not optimizing, try_redirect_by_replacing_jump will
2609 not allow us to redirect an edge by replacing a table jump. */
2610 && (!JUMP_P (BB_END (a))
2611 || ((!optimize || reload_completed)
2612 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2615 /* Merge block A and B. The blocks must be mergeable. */
2618 cfg_layout_merge_blocks (basic_block a, basic_block b)
2620 #ifdef ENABLE_CHECKING
2621 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2625 fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
2627 /* If there was a CODE_LABEL beginning B, delete it. */
2628 if (LABEL_P (BB_HEAD (b)))
2630 delete_insn (BB_HEAD (b));
2633 /* We should have fallthru edge in a, or we can do dummy redirection to get
2635 if (JUMP_P (BB_END (a)))
2636 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2637 gcc_assert (!JUMP_P (BB_END (a)));
2639 /* When not optimizing and the edge is the only place in RTL which holds
2640 some unique locus, emit a nop with that locus in between. */
2641 if (!optimize && EDGE_SUCC (a, 0)->goto_locus)
2643 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a));
2644 int goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2646 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
2647 insn = PREV_INSN (insn);
2648 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus))
2653 end = NEXT_INSN (BB_END (b));
2654 while (insn != end && !INSN_P (insn))
2655 insn = NEXT_INSN (insn);
2656 if (insn != end && INSN_LOCATOR (insn) != 0
2657 && locator_eq (INSN_LOCATOR (insn), goto_locus))
2662 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a);
2663 INSN_LOCATOR (BB_END (a)) = goto_locus;
2667 /* Possible line number notes should appear in between. */
2668 if (b->il.rtl->header)
2670 rtx first = BB_END (a), last;
2672 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2673 delete_insn_chain (NEXT_INSN (first), last, false);
2674 b->il.rtl->header = NULL;
2677 /* In the case basic blocks are not adjacent, move them around. */
2678 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2680 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2682 emit_insn_after_noloc (first, BB_END (a), a);
2683 /* Skip possible DELETED_LABEL insn. */
2684 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2685 first = NEXT_INSN (first);
2686 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2689 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
2690 We need to explicitly call. */
2691 update_bb_for_insn_chain (NEXT_INSN (first),
2695 delete_insn (first);
2697 /* Otherwise just re-associate the instructions. */
2702 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a);
2705 /* Skip possible DELETED_LABEL insn. */
2706 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2707 insn = NEXT_INSN (insn);
2708 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2710 BB_END (a) = BB_END (b);
2714 df_bb_delete (b->index);
2716 /* Possible tablejumps and barriers should appear after the block. */
2717 if (b->il.rtl->footer)
2719 if (!a->il.rtl->footer)
2720 a->il.rtl->footer = b->il.rtl->footer;
2723 rtx last = a->il.rtl->footer;
2725 while (NEXT_INSN (last))
2726 last = NEXT_INSN (last);
2727 NEXT_INSN (last) = b->il.rtl->footer;
2728 PREV_INSN (b->il.rtl->footer) = last;
2730 b->il.rtl->footer = NULL;
2734 fprintf (dump_file, "Merged blocks %d and %d.\n",
2735 a->index, b->index);
2741 cfg_layout_split_edge (edge e)
2743 basic_block new_bb =
2744 create_basic_block (e->src != ENTRY_BLOCK_PTR
2745 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2748 if (e->dest == EXIT_BLOCK_PTR)
2749 BB_COPY_PARTITION (new_bb, e->src);
2751 BB_COPY_PARTITION (new_bb, e->dest);
2752 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2753 redirect_edge_and_branch_force (e, new_bb);
2758 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2761 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2765 /* Return 1 if BB ends with a call, possibly followed by some
2766 instructions that must stay with the call, 0 otherwise. */
2769 rtl_block_ends_with_call_p (basic_block bb)
2771 rtx insn = BB_END (bb);
2773 while (!CALL_P (insn)
2774 && insn != BB_HEAD (bb)
2775 && (keep_with_call_p (insn)
2777 insn = PREV_INSN (insn);
2778 return (CALL_P (insn));
2781 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2784 rtl_block_ends_with_condjump_p (const_basic_block bb)
2786 return any_condjump_p (BB_END (bb));
2789 /* Return true if we need to add fake edge to exit.
2790 Helper function for rtl_flow_call_edges_add. */
2793 need_fake_edge_p (const_rtx insn)
2799 && !SIBLING_CALL_P (insn)
2800 && !find_reg_note (insn, REG_NORETURN, NULL)
2801 && !(RTL_CONST_OR_PURE_CALL_P (insn))))
2804 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2805 && MEM_VOLATILE_P (PATTERN (insn)))
2806 || (GET_CODE (PATTERN (insn)) == PARALLEL
2807 && asm_noperands (insn) != -1
2808 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2809 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2812 /* Add fake edges to the function exit for any non constant and non noreturn
2813 calls, volatile inline assembly in the bitmap of blocks specified by
2814 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2817 The goal is to expose cases in which entering a basic block does not imply
2818 that all subsequent instructions must be executed. */
2821 rtl_flow_call_edges_add (sbitmap blocks)
2824 int blocks_split = 0;
2825 int last_bb = last_basic_block;
2826 bool check_last_block = false;
2828 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2832 check_last_block = true;
2834 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2836 /* In the last basic block, before epilogue generation, there will be
2837 a fallthru edge to EXIT. Special care is required if the last insn
2838 of the last basic block is a call because make_edge folds duplicate
2839 edges, which would result in the fallthru edge also being marked
2840 fake, which would result in the fallthru edge being removed by
2841 remove_fake_edges, which would result in an invalid CFG.
2843 Moreover, we can't elide the outgoing fake edge, since the block
2844 profiler needs to take this into account in order to solve the minimal
2845 spanning tree in the case that the call doesn't return.
2847 Handle this by adding a dummy instruction in a new last basic block. */
2848 if (check_last_block)
2850 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2851 rtx insn = BB_END (bb);
2853 /* Back up past insns that must be kept in the same block as a call. */
2854 while (insn != BB_HEAD (bb)
2855 && keep_with_call_p (insn))
2856 insn = PREV_INSN (insn);
2858 if (need_fake_edge_p (insn))
2862 e = find_edge (bb, EXIT_BLOCK_PTR);
2865 insert_insn_on_edge (gen_use (const0_rtx), e);
2866 commit_edge_insertions ();
2871 /* Now add fake edges to the function exit for any non constant
2872 calls since there is no way that we can determine if they will
2875 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
2877 basic_block bb = BASIC_BLOCK (i);
2884 if (blocks && !TEST_BIT (blocks, i))
2887 for (insn = BB_END (bb); ; insn = prev_insn)
2889 prev_insn = PREV_INSN (insn);
2890 if (need_fake_edge_p (insn))
2893 rtx split_at_insn = insn;
2895 /* Don't split the block between a call and an insn that should
2896 remain in the same block as the call. */
2898 while (split_at_insn != BB_END (bb)
2899 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2900 split_at_insn = NEXT_INSN (split_at_insn);
2902 /* The handling above of the final block before the epilogue
2903 should be enough to verify that there is no edge to the exit
2904 block in CFG already. Calling make_edge in such case would
2905 cause us to mark that edge as fake and remove it later. */
2907 #ifdef ENABLE_CHECKING
2908 if (split_at_insn == BB_END (bb))
2910 e = find_edge (bb, EXIT_BLOCK_PTR);
2911 gcc_assert (e == NULL);
2915 /* Note that the following may create a new basic block
2916 and renumber the existing basic blocks. */
2917 if (split_at_insn != BB_END (bb))
2919 e = split_block (bb, split_at_insn);
2924 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2927 if (insn == BB_HEAD (bb))
2933 verify_flow_info ();
2935 return blocks_split;
2938 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2939 the conditional branch target, SECOND_HEAD should be the fall-thru
2940 there is no need to handle this here the loop versioning code handles
2941 this. the reason for SECON_HEAD is that it is needed for condition
2942 in trees, and this should be of the same type since it is a hook. */
2944 rtl_lv_add_condition_to_bb (basic_block first_head ,
2945 basic_block second_head ATTRIBUTE_UNUSED,
2946 basic_block cond_bb, void *comp_rtx)
2948 rtx label, seq, jump;
2949 rtx op0 = XEXP ((rtx)comp_rtx, 0);
2950 rtx op1 = XEXP ((rtx)comp_rtx, 1);
2951 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
2952 enum machine_mode mode;
2955 label = block_label (first_head);
2956 mode = GET_MODE (op0);
2957 if (mode == VOIDmode)
2958 mode = GET_MODE (op1);
2961 op0 = force_operand (op0, NULL_RTX);
2962 op1 = force_operand (op1, NULL_RTX);
2963 do_compare_rtx_and_jump (op0, op1, comp, 0,
2964 mode, NULL_RTX, NULL_RTX, label);
2965 jump = get_last_insn ();
2966 JUMP_LABEL (jump) = label;
2967 LABEL_NUSES (label)++;
2971 /* Add the new cond , in the new head. */
2972 emit_insn_after(seq, BB_END(cond_bb));
2976 /* Given a block B with unconditional branch at its end, get the
2977 store the return the branch edge and the fall-thru edge in
2978 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
2980 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
2981 edge *fallthru_edge)
2983 edge e = EDGE_SUCC (b, 0);
2985 if (e->flags & EDGE_FALLTHRU)
2988 *branch_edge = EDGE_SUCC (b, 1);
2993 *fallthru_edge = EDGE_SUCC (b, 1);
2998 init_rtl_bb_info (basic_block bb)
3000 gcc_assert (!bb->il.rtl);
3001 bb->il.rtl = GGC_CNEW (struct rtl_bb_info);
3005 /* Add EXPR to the end of basic block BB. */
3008 insert_insn_end_bb_new (rtx pat, basic_block bb)
3010 rtx insn = BB_END (bb);
3014 while (NEXT_INSN (pat_end) != NULL_RTX)
3015 pat_end = NEXT_INSN (pat_end);
3017 /* If the last insn is a jump, insert EXPR in front [taking care to
3018 handle cc0, etc. properly]. Similarly we need to care trapping
3019 instructions in presence of non-call exceptions. */
3022 || (NONJUMP_INSN_P (insn)
3023 && (!single_succ_p (bb)
3024 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
3029 /* If this is a jump table, then we can't insert stuff here. Since
3030 we know the previous real insn must be the tablejump, we insert
3031 the new instruction just before the tablejump. */
3032 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
3033 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
3034 insn = prev_real_insn (insn);
3037 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
3038 if cc0 isn't set. */
3039 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
3041 insn = XEXP (note, 0);
3044 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
3045 if (maybe_cc0_setter
3046 && INSN_P (maybe_cc0_setter)
3047 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
3048 insn = maybe_cc0_setter;
3051 /* FIXME: What if something in cc0/jump uses value set in new
3053 new_insn = emit_insn_before_noloc (pat, insn, bb);
3056 /* Likewise if the last insn is a call, as will happen in the presence
3057 of exception handling. */
3058 else if (CALL_P (insn)
3059 && (!single_succ_p (bb)
3060 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
3062 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
3063 we search backward and place the instructions before the first
3064 parameter is loaded. Do this for everyone for consistency and a
3065 presumption that we'll get better code elsewhere as well. */
3067 /* Since different machines initialize their parameter registers
3068 in different orders, assume nothing. Collect the set of all
3069 parameter registers. */
3070 insn = find_first_parameter_load (insn, BB_HEAD (bb));
3072 /* If we found all the parameter loads, then we want to insert
3073 before the first parameter load.
3075 If we did not find all the parameter loads, then we might have
3076 stopped on the head of the block, which could be a CODE_LABEL.
3077 If we inserted before the CODE_LABEL, then we would be putting
3078 the insn in the wrong basic block. In that case, put the insn
3079 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
3080 while (LABEL_P (insn)
3081 || NOTE_INSN_BASIC_BLOCK_P (insn))
3082 insn = NEXT_INSN (insn);
3084 new_insn = emit_insn_before_noloc (pat, insn, bb);
3087 new_insn = emit_insn_after_noloc (pat, insn, bb);
3092 /* Returns true if it is possible to remove edge E by redirecting
3093 it to the destination of the other edge from E->src. */
3096 rtl_can_remove_branch_p (const_edge e)
3098 const_basic_block src = e->src;
3099 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3100 const_rtx insn = BB_END (src), set;
3102 /* The conditions are taken from try_redirect_by_replacing_jump. */
3103 if (target == EXIT_BLOCK_PTR)
3106 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3109 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3110 || BB_PARTITION (src) != BB_PARTITION (target))
3113 if (!onlyjump_p (insn)
3114 || tablejump_p (insn, NULL, NULL))
3117 set = single_set (insn);
3118 if (!set || side_effects_p (set))
3124 /* Implementation of CFG manipulation for linearized RTL. */
3125 struct cfg_hooks rtl_cfg_hooks = {
3127 rtl_verify_flow_info,
3129 rtl_create_basic_block,
3130 rtl_redirect_edge_and_branch,
3131 rtl_redirect_edge_and_branch_force,
3132 rtl_can_remove_branch_p,
3135 rtl_move_block_after,
3136 rtl_can_merge_blocks, /* can_merge_blocks_p */
3140 NULL, /* can_duplicate_block_p */
3141 NULL, /* duplicate_block */
3143 rtl_make_forwarder_block,
3144 rtl_tidy_fallthru_edge,
3145 rtl_block_ends_with_call_p,
3146 rtl_block_ends_with_condjump_p,
3147 rtl_flow_call_edges_add,
3148 NULL, /* execute_on_growing_pred */
3149 NULL, /* execute_on_shrinking_pred */
3150 NULL, /* duplicate loop for trees */
3151 NULL, /* lv_add_condition_to_bb */
3152 NULL, /* lv_adjust_loop_header_phi*/
3153 NULL, /* extract_cond_bb_edges */
3154 NULL /* flush_pending_stmts */
3157 /* Implementation of CFG manipulation for cfg layout RTL, where
3158 basic block connected via fallthru edges does not have to be adjacent.
3159 This representation will hopefully become the default one in future
3160 version of the compiler. */
3162 /* We do not want to declare these functions in a header file, since they
3163 should only be used through the cfghooks interface, and we do not want to
3164 move them here since it would require also moving quite a lot of related
3165 code. They are in cfglayout.c. */
3166 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3167 extern basic_block cfg_layout_duplicate_bb (basic_block);
3169 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3171 rtl_verify_flow_info_1,
3173 cfg_layout_create_basic_block,
3174 cfg_layout_redirect_edge_and_branch,
3175 cfg_layout_redirect_edge_and_branch_force,
3176 rtl_can_remove_branch_p,
3177 cfg_layout_delete_block,
3178 cfg_layout_split_block,
3179 rtl_move_block_after,
3180 cfg_layout_can_merge_blocks_p,
3181 cfg_layout_merge_blocks,
3184 cfg_layout_can_duplicate_bb_p,
3185 cfg_layout_duplicate_bb,
3186 cfg_layout_split_edge,
3187 rtl_make_forwarder_block,
3189 rtl_block_ends_with_call_p,
3190 rtl_block_ends_with_condjump_p,
3191 rtl_flow_call_edges_add,
3192 NULL, /* execute_on_growing_pred */
3193 NULL, /* execute_on_shrinking_pred */
3194 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3195 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3196 NULL, /* lv_adjust_loop_header_phi*/
3197 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3198 NULL /* flush_pending_stmts */