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 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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-config.h"
57 #include "cfglayout.h"
62 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
63 /* ??? Should probably be using LABEL_NUSES instead. It would take a
64 bit of surgery to be able to use or co-opt the routines in jump. */
67 static int can_delete_note_p (rtx
);
68 static int can_delete_label_p (rtx
);
69 static void commit_one_edge_insertion (edge
, int);
70 static rtx
last_loop_beg_note (rtx
);
71 static bool back_edge_of_syntactic_loop_p (basic_block
, basic_block
);
72 static basic_block
rtl_split_edge (edge
);
73 static bool rtl_move_block_after (basic_block
, basic_block
);
74 static int rtl_verify_flow_info (void);
75 static basic_block
cfg_layout_split_block (basic_block
, void *);
76 static edge
cfg_layout_redirect_edge_and_branch (edge
, basic_block
);
77 static basic_block
cfg_layout_redirect_edge_and_branch_force (edge
, basic_block
);
78 static void cfg_layout_delete_block (basic_block
);
79 static void rtl_delete_block (basic_block
);
80 static basic_block
rtl_redirect_edge_and_branch_force (edge
, basic_block
);
81 static edge
rtl_redirect_edge_and_branch (edge
, basic_block
);
82 static basic_block
rtl_split_block (basic_block
, void *);
83 static void rtl_dump_bb (basic_block
, FILE *, int);
84 static int rtl_verify_flow_info_1 (void);
85 static void mark_killed_regs (rtx
, rtx
, void *);
86 static void rtl_make_forwarder_block (edge
);
88 /* Return true if NOTE is not one of the ones that must be kept paired,
89 so that we may simply delete it. */
92 can_delete_note_p (rtx note
)
94 return (NOTE_LINE_NUMBER (note
) == NOTE_INSN_DELETED
95 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_BASIC_BLOCK
96 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_UNLIKELY_EXECUTED_CODE
);
99 /* True if a given label can be deleted. */
102 can_delete_label_p (rtx label
)
104 return (!LABEL_PRESERVE_P (label
)
105 /* User declared labels must be preserved. */
106 && LABEL_NAME (label
) == 0
107 && !in_expr_list_p (forced_labels
, label
)
108 && !in_expr_list_p (label_value_list
, label
));
111 /* Delete INSN by patching it out. Return the next insn. */
114 delete_insn (rtx insn
)
116 rtx next
= NEXT_INSN (insn
);
118 bool really_delete
= true;
122 /* Some labels can't be directly removed from the INSN chain, as they
123 might be references via variables, constant pool etc.
124 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
125 if (! can_delete_label_p (insn
))
127 const char *name
= LABEL_NAME (insn
);
129 really_delete
= false;
130 PUT_CODE (insn
, NOTE
);
131 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
132 NOTE_DELETED_LABEL_NAME (insn
) = name
;
135 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
140 /* If this insn has already been deleted, something is very wrong. */
141 gcc_assert (!INSN_DELETED_P (insn
));
143 INSN_DELETED_P (insn
) = 1;
146 /* If deleting a jump, decrement the use count of the label. Deleting
147 the label itself should happen in the normal course of block merging. */
150 && LABEL_P (JUMP_LABEL (insn
)))
151 LABEL_NUSES (JUMP_LABEL (insn
))--;
153 /* Also if deleting an insn that references a label. */
156 while ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)) != NULL_RTX
157 && LABEL_P (XEXP (note
, 0)))
159 LABEL_NUSES (XEXP (note
, 0))--;
160 remove_note (insn
, note
);
165 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
166 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
168 rtx pat
= PATTERN (insn
);
169 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
170 int len
= XVECLEN (pat
, diff_vec_p
);
173 for (i
= 0; i
< len
; i
++)
175 rtx label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
177 /* When deleting code in bulk (e.g. removing many unreachable
178 blocks) we can delete a label that's a target of the vector
179 before deleting the vector itself. */
181 LABEL_NUSES (label
)--;
188 /* Like delete_insn but also purge dead edges from BB. */
190 delete_insn_and_edges (rtx insn
)
196 && BLOCK_FOR_INSN (insn
)
197 && BB_END (BLOCK_FOR_INSN (insn
)) == insn
)
199 x
= delete_insn (insn
);
201 purge_dead_edges (BLOCK_FOR_INSN (insn
));
205 /* Unlink a chain of insns between START and FINISH, leaving notes
206 that must be paired. */
209 delete_insn_chain (rtx start
, rtx finish
)
213 /* Unchain the insns one by one. It would be quicker to delete all of these
214 with a single unchaining, rather than one at a time, but we need to keep
218 next
= NEXT_INSN (start
);
219 if (NOTE_P (start
) && !can_delete_note_p (start
))
222 next
= delete_insn (start
);
230 /* Like delete_insn but also purge dead edges from BB. */
232 delete_insn_chain_and_edges (rtx first
, rtx last
)
237 && BLOCK_FOR_INSN (last
)
238 && BB_END (BLOCK_FOR_INSN (last
)) == last
)
240 delete_insn_chain (first
, last
);
242 purge_dead_edges (BLOCK_FOR_INSN (last
));
245 /* Create a new basic block consisting of the instructions between HEAD and END
246 inclusive. This function is designed to allow fast BB construction - reuses
247 the note and basic block struct in BB_NOTE, if any and do not grow
248 BASIC_BLOCK chain and should be used directly only by CFG construction code.
249 END can be NULL in to create new empty basic block before HEAD. Both END
250 and HEAD can be NULL to create basic block at the end of INSN chain.
251 AFTER is the basic block we should be put after. */
254 create_basic_block_structure (rtx head
, rtx end
, rtx bb_note
, basic_block after
)
259 && (bb
= NOTE_BASIC_BLOCK (bb_note
)) != NULL
262 /* If we found an existing note, thread it back onto the chain. */
270 after
= PREV_INSN (head
);
274 if (after
!= bb_note
&& NEXT_INSN (after
) != bb_note
)
275 reorder_insns_nobb (bb_note
, bb_note
, after
);
279 /* Otherwise we must create a note and a basic block structure. */
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
++;
311 link_block (bb
, after
);
312 BASIC_BLOCK (bb
->index
) = bb
;
313 update_bb_for_insn (bb
);
314 BB_SET_PARTITION (bb
, BB_UNPARTITIONED
);
316 /* Tag the block so that we know it has been used when considering
317 other basic block notes. */
323 /* Create new basic block consisting of instructions in between HEAD and END
324 and place it to the BB chain after block AFTER. END can be NULL in to
325 create new empty basic block before HEAD. Both END and HEAD can be NULL to
326 create basic block at the end of INSN chain. */
329 rtl_create_basic_block (void *headp
, void *endp
, basic_block after
)
331 rtx head
= headp
, end
= endp
;
334 /* Grow the basic block array if needed. */
335 if ((size_t) last_basic_block
>= VARRAY_SIZE (basic_block_info
))
337 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
338 VARRAY_GROW (basic_block_info
, new_size
);
343 bb
= create_basic_block_structure (head
, end
, NULL
, after
);
349 cfg_layout_create_basic_block (void *head
, void *end
, basic_block after
)
351 basic_block newbb
= rtl_create_basic_block (head
, end
, after
);
353 initialize_bb_rbi (newbb
);
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 maybe_remove_eh_handler (insn
);
377 /* Include any jump table following the basic block. */
379 if (tablejump_p (end
, NULL
, &tmp
))
382 /* Include any barriers that may follow the basic block. */
383 tmp
= next_nonnote_insn (end
);
384 while (tmp
&& BARRIER_P (tmp
))
387 tmp
= next_nonnote_insn (end
);
390 /* Selectively delete the entire chain. */
392 delete_insn_chain (insn
, end
);
395 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
398 compute_bb_for_insn (void)
404 rtx end
= BB_END (bb
);
407 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
409 BLOCK_FOR_INSN (insn
) = bb
;
416 /* Release the basic_block_for_insn array. */
419 free_bb_for_insn (void)
422 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
423 if (!BARRIER_P (insn
))
424 BLOCK_FOR_INSN (insn
) = NULL
;
427 /* Return RTX to emit after when we want to emit code on the entry of function. */
429 entry_of_function (void)
431 return (n_basic_blocks
? BB_HEAD (ENTRY_BLOCK_PTR
->next_bb
) : get_insns ());
434 /* Update insns block within BB. */
437 update_bb_for_insn (basic_block bb
)
441 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
443 if (!BARRIER_P (insn
))
444 set_block_for_insn (insn
, bb
);
445 if (insn
== BB_END (bb
))
450 /* Creates a new basic block just after basic block B by splitting
451 everything after specified instruction I. */
454 rtl_split_block (basic_block bb
, void *insnp
)
463 insn
= first_insn_after_basic_block_note (bb
);
466 insn
= PREV_INSN (insn
);
468 insn
= get_last_insn ();
471 /* We probably should check type of the insn so that we do not create
472 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
474 if (insn
== BB_END (bb
))
475 emit_note_after (NOTE_INSN_DELETED
, insn
);
477 /* Create the new basic block. */
478 new_bb
= create_basic_block (NEXT_INSN (insn
), BB_END (bb
), bb
);
479 BB_COPY_PARTITION (new_bb
, bb
);
482 /* Redirect the outgoing edges. */
483 new_bb
->succs
= bb
->succs
;
485 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
488 if (bb
->global_live_at_start
)
490 new_bb
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
491 new_bb
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
492 COPY_REG_SET (new_bb
->global_live_at_end
, bb
->global_live_at_end
);
494 /* We now have to calculate which registers are live at the end
495 of the split basic block and at the start of the new basic
496 block. Start with those registers that are known to be live
497 at the end of the original basic block and get
498 propagate_block to determine which registers are live. */
499 COPY_REG_SET (new_bb
->global_live_at_start
, bb
->global_live_at_end
);
500 propagate_block (new_bb
, new_bb
->global_live_at_start
, NULL
, NULL
, 0);
501 COPY_REG_SET (bb
->global_live_at_end
,
502 new_bb
->global_live_at_start
);
503 #ifdef HAVE_conditional_execution
504 /* In the presence of conditional execution we are not able to update
505 liveness precisely. */
506 if (reload_completed
)
508 bb
->flags
|= BB_DIRTY
;
509 new_bb
->flags
|= BB_DIRTY
;
517 /* Blocks A and B are to be merged into a single block A. The insns
518 are already contiguous. */
521 rtl_merge_blocks (basic_block a
, basic_block b
)
523 rtx b_head
= BB_HEAD (b
), b_end
= BB_END (b
), a_end
= BB_END (a
);
524 rtx del_first
= NULL_RTX
, del_last
= NULL_RTX
;
527 /* If there was a CODE_LABEL beginning B, delete it. */
528 if (LABEL_P (b_head
))
530 /* Detect basic blocks with nothing but a label. This can happen
531 in particular at the end of a function. */
535 del_first
= del_last
= b_head
;
536 b_head
= NEXT_INSN (b_head
);
539 /* Delete the basic block note and handle blocks containing just that
541 if (NOTE_INSN_BASIC_BLOCK_P (b_head
))
549 b_head
= NEXT_INSN (b_head
);
552 /* If there was a jump out of A, delete it. */
557 for (prev
= PREV_INSN (a_end
); ; prev
= PREV_INSN (prev
))
559 || NOTE_LINE_NUMBER (prev
) == NOTE_INSN_BASIC_BLOCK
560 || prev
== BB_HEAD (a
))
566 /* If this was a conditional jump, we need to also delete
567 the insn that set cc0. */
568 if (only_sets_cc0_p (prev
))
572 prev
= prev_nonnote_insn (prev
);
579 a_end
= PREV_INSN (del_first
);
581 else if (BARRIER_P (NEXT_INSN (a_end
)))
582 del_first
= NEXT_INSN (a_end
);
584 /* Delete everything marked above as well as crap that might be
585 hanging out between the two blocks. */
587 delete_insn_chain (del_first
, del_last
);
589 /* Reassociate the insns of B with A. */
594 for (x
= a_end
; x
!= b_end
; x
= NEXT_INSN (x
))
595 set_block_for_insn (x
, a
);
597 set_block_for_insn (b_end
, a
);
605 /* Return true when block A and B can be merged. */
607 rtl_can_merge_blocks (basic_block a
,basic_block b
)
609 /* If we are partitioning hot/cold basic blocks, we don't want to
610 mess up unconditional or indirect jumps that cross between hot
613 Basic block partitioning may result in some jumps that appear to
614 be optimizable (or blocks that appear to be mergeable), but which really
615 must be left untouched (they are required to make it safely across
616 partition boundaries). See the comments at the top of
617 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
619 if (flag_reorder_blocks_and_partition
620 && (find_reg_note (BB_END (a
), REG_CROSSING_JUMP
, NULL_RTX
)
621 || find_reg_note (BB_END (b
), REG_CROSSING_JUMP
, NULL_RTX
)
622 || BB_PARTITION (a
) != BB_PARTITION (b
)))
625 /* There must be exactly one edge in between the blocks. */
626 return (single_succ_p (a
)
627 && single_succ (a
) == b
630 /* Must be simple edge. */
631 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
633 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
634 /* If the jump insn has side effects,
635 we can't kill the edge. */
636 && (!JUMP_P (BB_END (a
))
638 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
641 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
645 block_label (basic_block block
)
647 if (block
== EXIT_BLOCK_PTR
)
650 if (!LABEL_P (BB_HEAD (block
)))
652 BB_HEAD (block
) = emit_label_before (gen_label_rtx (), BB_HEAD (block
));
655 return BB_HEAD (block
);
658 /* Attempt to perform edge redirection by replacing possibly complex jump
659 instruction by unconditional jump or removing jump completely. This can
660 apply only if all edges now point to the same block. The parameters and
661 return values are equivalent to redirect_edge_and_branch. */
664 try_redirect_by_replacing_jump (edge e
, basic_block target
, bool in_cfglayout
)
666 basic_block src
= e
->src
;
667 rtx insn
= BB_END (src
), kill_from
;
671 /* If we are partitioning hot/cold basic blocks, we don't want to
672 mess up unconditional or indirect jumps that cross between hot
675 Basic block partitioning may result in some jumps that appear to
676 be optimizable (or blocks that appear to be mergeable), but which really
677 must be left untouched (they are required to make it safely across
678 partition boundaries). See the comments at the top of
679 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
681 if (flag_reorder_blocks_and_partition
682 && (find_reg_note (insn
, REG_CROSSING_JUMP
, NULL_RTX
)
683 || BB_PARTITION (src
) != BB_PARTITION (target
)))
686 /* We can replace or remove a complex jump only when we have exactly
687 two edges. Also, if we have exactly one outgoing edge, we can
689 if (EDGE_COUNT (src
->succs
) >= 3
690 /* Verify that all targets will be TARGET. Specifically, the
691 edge that is not E must also go to TARGET. */
692 || (EDGE_COUNT (src
->succs
) == 2
693 && EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
))
696 if (!onlyjump_p (insn
))
698 if ((!optimize
|| reload_completed
) && tablejump_p (insn
, NULL
, NULL
))
701 /* Avoid removing branch with side effects. */
702 set
= single_set (insn
);
703 if (!set
|| side_effects_p (set
))
706 /* In case we zap a conditional jump, we'll need to kill
707 the cc0 setter too. */
710 if (reg_mentioned_p (cc0_rtx
, PATTERN (insn
)))
711 kill_from
= PREV_INSN (insn
);
714 /* See if we can create the fallthru edge. */
715 if (in_cfglayout
|| can_fallthru (src
, target
))
718 fprintf (dump_file
, "Removing jump %i.\n", INSN_UID (insn
));
721 /* Selectively unlink whole insn chain. */
724 rtx insn
= src
->rbi
->footer
;
726 delete_insn_chain (kill_from
, BB_END (src
));
728 /* Remove barriers but keep jumptables. */
731 if (BARRIER_P (insn
))
733 if (PREV_INSN (insn
))
734 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
736 src
->rbi
->footer
= NEXT_INSN (insn
);
737 if (NEXT_INSN (insn
))
738 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
742 insn
= NEXT_INSN (insn
);
746 delete_insn_chain (kill_from
, PREV_INSN (BB_HEAD (target
)));
749 /* If this already is simplejump, redirect it. */
750 else if (simplejump_p (insn
))
752 if (e
->dest
== target
)
755 fprintf (dump_file
, "Redirecting jump %i from %i to %i.\n",
756 INSN_UID (insn
), e
->dest
->index
, target
->index
);
757 if (!redirect_jump (insn
, block_label (target
), 0))
759 gcc_assert (target
== EXIT_BLOCK_PTR
);
764 /* Cannot do anything for target exit block. */
765 else if (target
== EXIT_BLOCK_PTR
)
768 /* Or replace possibly complicated jump insn by simple jump insn. */
771 rtx target_label
= block_label (target
);
772 rtx barrier
, label
, table
;
774 emit_jump_insn_after_noloc (gen_jump (target_label
), insn
);
775 JUMP_LABEL (BB_END (src
)) = target_label
;
776 LABEL_NUSES (target_label
)++;
778 fprintf (dump_file
, "Replacing insn %i by jump %i\n",
779 INSN_UID (insn
), INSN_UID (BB_END (src
)));
782 delete_insn_chain (kill_from
, insn
);
784 /* Recognize a tablejump that we are converting to a
785 simple jump and remove its associated CODE_LABEL
786 and ADDR_VEC or ADDR_DIFF_VEC. */
787 if (tablejump_p (insn
, &label
, &table
))
788 delete_insn_chain (label
, table
);
790 barrier
= next_nonnote_insn (BB_END (src
));
791 if (!barrier
|| !BARRIER_P (barrier
))
792 emit_barrier_after (BB_END (src
));
795 if (barrier
!= NEXT_INSN (BB_END (src
)))
797 /* Move the jump before barrier so that the notes
798 which originally were or were created before jump table are
799 inside the basic block. */
800 rtx new_insn
= BB_END (src
);
803 for (tmp
= NEXT_INSN (BB_END (src
)); tmp
!= barrier
;
804 tmp
= NEXT_INSN (tmp
))
805 set_block_for_insn (tmp
, src
);
807 NEXT_INSN (PREV_INSN (new_insn
)) = NEXT_INSN (new_insn
);
808 PREV_INSN (NEXT_INSN (new_insn
)) = PREV_INSN (new_insn
);
810 NEXT_INSN (new_insn
) = barrier
;
811 NEXT_INSN (PREV_INSN (barrier
)) = new_insn
;
813 PREV_INSN (new_insn
) = PREV_INSN (barrier
);
814 PREV_INSN (barrier
) = new_insn
;
819 /* Keep only one edge out and set proper flags. */
820 if (!single_succ_p (src
))
822 gcc_assert (single_succ_p (src
));
824 e
= single_succ_edge (src
);
826 e
->flags
= EDGE_FALLTHRU
;
830 e
->probability
= REG_BR_PROB_BASE
;
831 e
->count
= src
->count
;
833 /* We don't want a block to end on a line-number note since that has
834 the potential of changing the code between -g and not -g. */
835 while (NOTE_P (BB_END (e
->src
))
836 && NOTE_LINE_NUMBER (BB_END (e
->src
)) >= 0)
837 delete_insn (BB_END (e
->src
));
839 if (e
->dest
!= target
)
840 redirect_edge_succ (e
, target
);
845 /* Return last loop_beg note appearing after INSN, before start of next
846 basic block. Return INSN if there are no such notes.
848 When emitting jump to redirect a fallthru edge, it should always appear
849 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
850 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
854 last_loop_beg_note (rtx insn
)
858 for (insn
= NEXT_INSN (insn
); insn
&& NOTE_P (insn
)
859 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
;
860 insn
= NEXT_INSN (insn
))
861 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
867 /* Redirect edge representing branch of (un)conditional jump or tablejump,
870 redirect_branch_edge (edge e
, basic_block target
)
873 rtx old_label
= BB_HEAD (e
->dest
);
874 basic_block src
= e
->src
;
875 rtx insn
= BB_END (src
);
877 /* We can only redirect non-fallthru edges of jump insn. */
878 if (e
->flags
& EDGE_FALLTHRU
)
880 else if (!JUMP_P (insn
))
883 /* Recognize a tablejump and adjust all matching cases. */
884 if (tablejump_p (insn
, NULL
, &tmp
))
888 rtx new_label
= block_label (target
);
890 if (target
== EXIT_BLOCK_PTR
)
892 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
893 vec
= XVEC (PATTERN (tmp
), 0);
895 vec
= XVEC (PATTERN (tmp
), 1);
897 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
898 if (XEXP (RTVEC_ELT (vec
, j
), 0) == old_label
)
900 RTVEC_ELT (vec
, j
) = gen_rtx_LABEL_REF (Pmode
, new_label
);
901 --LABEL_NUSES (old_label
);
902 ++LABEL_NUSES (new_label
);
905 /* Handle casesi dispatch insns. */
906 if ((tmp
= single_set (insn
)) != NULL
907 && SET_DEST (tmp
) == pc_rtx
908 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
909 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
910 && XEXP (XEXP (SET_SRC (tmp
), 2), 0) == old_label
)
912 XEXP (SET_SRC (tmp
), 2) = gen_rtx_LABEL_REF (VOIDmode
,
914 --LABEL_NUSES (old_label
);
915 ++LABEL_NUSES (new_label
);
920 /* ?? We may play the games with moving the named labels from
921 one basic block to the other in case only one computed_jump is
923 if (computed_jump_p (insn
)
924 /* A return instruction can't be redirected. */
925 || returnjump_p (insn
))
928 /* If the insn doesn't go where we think, we're confused. */
929 gcc_assert (JUMP_LABEL (insn
) == old_label
);
931 /* If the substitution doesn't succeed, die. This can happen
932 if the back end emitted unrecognizable instructions or if
933 target is exit block on some arches. */
934 if (!redirect_jump (insn
, block_label (target
), 0))
936 gcc_assert (target
== EXIT_BLOCK_PTR
);
942 fprintf (dump_file
, "Edge %i->%i redirected to %i\n",
943 e
->src
->index
, e
->dest
->index
, target
->index
);
945 if (e
->dest
!= target
)
946 e
= redirect_edge_succ_nodup (e
, target
);
950 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
951 expense of adding new instructions or reordering basic blocks.
953 Function can be also called with edge destination equivalent to the TARGET.
954 Then it should try the simplifications and do nothing if none is possible.
956 Return edge representing the branch if transformation succeeded. Return NULL
958 We still return NULL in case E already destinated TARGET and we didn't
959 managed to simplify instruction stream. */
962 rtl_redirect_edge_and_branch (edge e
, basic_block target
)
965 basic_block src
= e
->src
;
967 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
970 if (e
->dest
== target
)
973 if ((ret
= try_redirect_by_replacing_jump (e
, target
, false)) != NULL
)
975 src
->flags
|= BB_DIRTY
;
979 ret
= redirect_branch_edge (e
, target
);
983 src
->flags
|= BB_DIRTY
;
987 /* Like force_nonfallthru below, but additionally performs redirection
988 Used by redirect_edge_and_branch_force. */
991 force_nonfallthru_and_redirect (edge e
, basic_block target
)
993 basic_block jump_block
, new_bb
= NULL
, src
= e
->src
;
996 int abnormal_edge_flags
= 0;
998 /* In the case the last instruction is conditional jump to the next
999 instruction, first redirect the jump itself and then continue
1000 by creating a basic block afterwards to redirect fallthru edge. */
1001 if (e
->src
!= ENTRY_BLOCK_PTR
&& e
->dest
!= EXIT_BLOCK_PTR
1002 && any_condjump_p (BB_END (e
->src
))
1003 /* When called from cfglayout, fallthru edges do not
1004 necessarily go to the next block. */
1005 && e
->src
->next_bb
== e
->dest
1006 && JUMP_LABEL (BB_END (e
->src
)) == BB_HEAD (e
->dest
))
1009 edge b
= unchecked_make_edge (e
->src
, target
, 0);
1012 redirected
= redirect_jump (BB_END (e
->src
), block_label (target
), 0);
1013 gcc_assert (redirected
);
1015 note
= find_reg_note (BB_END (e
->src
), REG_BR_PROB
, NULL_RTX
);
1018 int prob
= INTVAL (XEXP (note
, 0));
1020 b
->probability
= prob
;
1021 b
->count
= e
->count
* prob
/ REG_BR_PROB_BASE
;
1022 e
->probability
-= e
->probability
;
1023 e
->count
-= b
->count
;
1024 if (e
->probability
< 0)
1031 if (e
->flags
& EDGE_ABNORMAL
)
1033 /* Irritating special case - fallthru edge to the same block as abnormal
1035 We can't redirect abnormal edge, but we still can split the fallthru
1036 one and create separate abnormal edge to original destination.
1037 This allows bb-reorder to make such edge non-fallthru. */
1038 gcc_assert (e
->dest
== target
);
1039 abnormal_edge_flags
= e
->flags
& ~(EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
);
1040 e
->flags
&= EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
;
1044 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1045 if (e
->src
== ENTRY_BLOCK_PTR
)
1047 /* We can't redirect the entry block. Create an empty block
1048 at the start of the function which we use to add the new
1054 basic_block bb
= create_basic_block (BB_HEAD (e
->dest
), NULL
, ENTRY_BLOCK_PTR
);
1056 /* Change the existing edge's source to be the new block, and add
1057 a new edge from the entry block to the new block. */
1059 for (ei
= ei_start (ENTRY_BLOCK_PTR
->succs
); (tmp
= ei_safe_edge (ei
)); )
1063 VEC_unordered_remove (edge
, ENTRY_BLOCK_PTR
->succs
, ei
.index
);
1073 VEC_safe_push (edge
, bb
->succs
, e
);
1074 make_single_succ_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_FALLTHRU
);
1078 if (EDGE_COUNT (e
->src
->succs
) >= 2 || abnormal_edge_flags
)
1080 /* Create the new structures. */
1082 /* If the old block ended with a tablejump, skip its table
1083 by searching forward from there. Otherwise start searching
1084 forward from the last instruction of the old block. */
1085 if (!tablejump_p (BB_END (e
->src
), NULL
, ¬e
))
1086 note
= BB_END (e
->src
);
1088 /* Position the new block correctly relative to loop notes. */
1089 note
= last_loop_beg_note (note
);
1090 note
= NEXT_INSN (note
);
1092 jump_block
= create_basic_block (note
, NULL
, e
->src
);
1093 jump_block
->count
= e
->count
;
1094 jump_block
->frequency
= EDGE_FREQUENCY (e
);
1095 jump_block
->loop_depth
= target
->loop_depth
;
1097 if (target
->global_live_at_start
)
1099 jump_block
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1100 jump_block
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1101 COPY_REG_SET (jump_block
->global_live_at_start
,
1102 target
->global_live_at_start
);
1103 COPY_REG_SET (jump_block
->global_live_at_end
,
1104 target
->global_live_at_start
);
1107 /* Make sure new block ends up in correct hot/cold section. */
1109 BB_COPY_PARTITION (jump_block
, e
->src
);
1110 if (flag_reorder_blocks_and_partition
1111 && targetm
.have_named_sections
)
1113 if (BB_PARTITION (jump_block
) == BB_COLD_PARTITION
)
1115 rtx bb_note
, new_note
;
1116 for (bb_note
= BB_HEAD (jump_block
);
1117 bb_note
&& bb_note
!= NEXT_INSN (BB_END (jump_block
));
1118 bb_note
= NEXT_INSN (bb_note
))
1119 if (NOTE_P (bb_note
)
1120 && NOTE_LINE_NUMBER (bb_note
) == NOTE_INSN_BASIC_BLOCK
)
1122 new_note
= emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE
,
1124 NOTE_BASIC_BLOCK (new_note
) = jump_block
;
1126 if (JUMP_P (BB_END (jump_block
))
1127 && !any_condjump_p (BB_END (jump_block
))
1128 && (single_succ_edge (jump_block
)->flags
& EDGE_CROSSING
))
1129 REG_NOTES (BB_END (jump_block
)) = gen_rtx_EXPR_LIST
1130 (REG_CROSSING_JUMP
, NULL_RTX
,
1131 REG_NOTES (BB_END (jump_block
)));
1135 new_edge
= make_edge (e
->src
, jump_block
, EDGE_FALLTHRU
);
1136 new_edge
->probability
= e
->probability
;
1137 new_edge
->count
= e
->count
;
1139 /* Redirect old edge. */
1140 redirect_edge_pred (e
, jump_block
);
1141 e
->probability
= REG_BR_PROB_BASE
;
1143 new_bb
= jump_block
;
1146 jump_block
= e
->src
;
1148 e
->flags
&= ~EDGE_FALLTHRU
;
1149 if (target
== EXIT_BLOCK_PTR
)
1152 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block
));
1159 rtx label
= block_label (target
);
1160 emit_jump_insn_after_noloc (gen_jump (label
), BB_END (jump_block
));
1161 JUMP_LABEL (BB_END (jump_block
)) = label
;
1162 LABEL_NUSES (label
)++;
1165 emit_barrier_after (BB_END (jump_block
));
1166 redirect_edge_succ_nodup (e
, target
);
1168 if (abnormal_edge_flags
)
1169 make_edge (src
, target
, abnormal_edge_flags
);
1174 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1175 (and possibly create new basic block) to make edge non-fallthru.
1176 Return newly created BB or NULL if none. */
1179 force_nonfallthru (edge e
)
1181 return force_nonfallthru_and_redirect (e
, e
->dest
);
1184 /* Redirect edge even at the expense of creating new jump insn or
1185 basic block. Return new basic block if created, NULL otherwise.
1186 Abort if conversion is impossible. */
1189 rtl_redirect_edge_and_branch_force (edge e
, basic_block target
)
1191 if (redirect_edge_and_branch (e
, target
)
1192 || e
->dest
== target
)
1195 /* In case the edge redirection failed, try to force it to be non-fallthru
1196 and redirect newly created simplejump. */
1197 return force_nonfallthru_and_redirect (e
, target
);
1200 /* The given edge should potentially be a fallthru edge. If that is in
1201 fact true, delete the jump and barriers that are in the way. */
1204 rtl_tidy_fallthru_edge (edge e
)
1207 basic_block b
= e
->src
, c
= b
->next_bb
;
1209 /* ??? In a late-running flow pass, other folks may have deleted basic
1210 blocks by nopping out blocks, leaving multiple BARRIERs between here
1211 and the target label. They ought to be chastized and fixed.
1213 We can also wind up with a sequence of undeletable labels between
1214 one block and the next.
1216 So search through a sequence of barriers, labels, and notes for
1217 the head of block C and assert that we really do fall through. */
1219 for (q
= NEXT_INSN (BB_END (b
)); q
!= BB_HEAD (c
); q
= NEXT_INSN (q
))
1223 /* Remove what will soon cease being the jump insn from the source block.
1224 If block B consisted only of this single jump, turn it into a deleted
1229 && (any_uncondjump_p (q
)
1230 || single_succ_p (b
)))
1233 /* If this was a conditional jump, we need to also delete
1234 the insn that set cc0. */
1235 if (any_condjump_p (q
) && only_sets_cc0_p (PREV_INSN (q
)))
1241 /* We don't want a block to end on a line-number note since that has
1242 the potential of changing the code between -g and not -g. */
1243 while (NOTE_P (q
) && NOTE_LINE_NUMBER (q
) >= 0)
1247 /* Selectively unlink the sequence. */
1248 if (q
!= PREV_INSN (BB_HEAD (c
)))
1249 delete_insn_chain (NEXT_INSN (q
), PREV_INSN (BB_HEAD (c
)));
1251 e
->flags
|= EDGE_FALLTHRU
;
1254 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1255 is back edge of syntactic loop. */
1258 back_edge_of_syntactic_loop_p (basic_block bb1
, basic_block bb2
)
1267 /* ??? Could we guarantee that bb indices are monotone, so that we could
1268 just compare them? */
1269 for (bb
= bb1
; bb
&& bb
!= bb2
; bb
= bb
->next_bb
)
1275 for (insn
= BB_END (bb1
); insn
!= BB_HEAD (bb2
) && count
>= 0;
1276 insn
= NEXT_INSN (insn
))
1279 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1281 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1288 /* Should move basic block BB after basic block AFTER. NIY. */
1291 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED
,
1292 basic_block after ATTRIBUTE_UNUSED
)
1297 /* Split a (typically critical) edge. Return the new block.
1298 Abort on abnormal edges.
1300 ??? The code generally expects to be called on critical edges.
1301 The case of a block ending in an unconditional jump to a
1302 block with multiple predecessors is not handled optimally. */
1305 rtl_split_edge (edge edge_in
)
1310 /* Abnormal edges cannot be split. */
1311 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
1313 /* We are going to place the new block in front of edge destination.
1314 Avoid existence of fallthru predecessors. */
1315 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1320 FOR_EACH_EDGE (e
, ei
, edge_in
->dest
->preds
)
1321 if (e
->flags
& EDGE_FALLTHRU
)
1325 force_nonfallthru (e
);
1328 /* Create the basic block note.
1330 Where we place the note can have a noticeable impact on the generated
1331 code. Consider this cfg:
1341 If we need to insert an insn on the edge from block 0 to block 1,
1342 we want to ensure the instructions we insert are outside of any
1343 loop notes that physically sit between block 0 and block 1. Otherwise
1344 we confuse the loop optimizer into thinking the loop is a phony. */
1346 if (edge_in
->dest
!= EXIT_BLOCK_PTR
1347 && PREV_INSN (BB_HEAD (edge_in
->dest
))
1348 && NOTE_P (PREV_INSN (BB_HEAD (edge_in
->dest
)))
1349 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in
->dest
)))
1350 == NOTE_INSN_LOOP_BEG
)
1351 && !back_edge_of_syntactic_loop_p (edge_in
->dest
, edge_in
->src
))
1352 before
= PREV_INSN (BB_HEAD (edge_in
->dest
));
1353 else if (edge_in
->dest
!= EXIT_BLOCK_PTR
)
1354 before
= BB_HEAD (edge_in
->dest
);
1358 /* If this is a fall through edge to the exit block, the blocks might be
1359 not adjacent, and the right place is the after the source. */
1360 if (edge_in
->flags
& EDGE_FALLTHRU
&& edge_in
->dest
== EXIT_BLOCK_PTR
)
1362 before
= NEXT_INSN (BB_END (edge_in
->src
));
1365 && NOTE_LINE_NUMBER (before
) == NOTE_INSN_LOOP_END
)
1366 before
= NEXT_INSN (before
);
1367 bb
= create_basic_block (before
, NULL
, edge_in
->src
);
1368 BB_COPY_PARTITION (bb
, edge_in
->src
);
1372 bb
= create_basic_block (before
, NULL
, edge_in
->dest
->prev_bb
);
1373 /* ??? Why not edge_in->dest->prev_bb here? */
1374 BB_COPY_PARTITION (bb
, edge_in
->dest
);
1377 /* ??? This info is likely going to be out of date very soon. */
1378 if (edge_in
->dest
->global_live_at_start
)
1380 bb
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1381 bb
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1382 COPY_REG_SET (bb
->global_live_at_start
,
1383 edge_in
->dest
->global_live_at_start
);
1384 COPY_REG_SET (bb
->global_live_at_end
,
1385 edge_in
->dest
->global_live_at_start
);
1388 make_single_succ_edge (bb
, edge_in
->dest
, EDGE_FALLTHRU
);
1390 /* For non-fallthru edges, we must adjust the predecessor's
1391 jump instruction to target our new block. */
1392 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1394 edge redirected
= redirect_edge_and_branch (edge_in
, bb
);
1395 gcc_assert (redirected
);
1398 redirect_edge_succ (edge_in
, bb
);
1403 /* Queue instructions for insertion on an edge between two basic blocks.
1404 The new instructions and basic blocks (if any) will not appear in the
1405 CFG until commit_edge_insertions is called. */
1408 insert_insn_on_edge (rtx pattern
, edge e
)
1410 /* We cannot insert instructions on an abnormal critical edge.
1411 It will be easier to find the culprit if we die now. */
1412 gcc_assert (!((e
->flags
& EDGE_ABNORMAL
) && EDGE_CRITICAL_P (e
)));
1414 if (e
->insns
.r
== NULL_RTX
)
1417 push_to_sequence (e
->insns
.r
);
1419 emit_insn (pattern
);
1421 e
->insns
.r
= get_insns ();
1425 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1426 registers that are killed by the store. */
1428 mark_killed_regs (rtx reg
, rtx set ATTRIBUTE_UNUSED
, void *data
)
1430 regset killed
= data
;
1433 if (GET_CODE (reg
) == SUBREG
)
1434 reg
= SUBREG_REG (reg
);
1437 regno
= REGNO (reg
);
1438 if (regno
>= FIRST_PSEUDO_REGISTER
)
1439 SET_REGNO_REG_SET (killed
, regno
);
1442 for (i
= 0; i
< (int) hard_regno_nregs
[regno
][GET_MODE (reg
)]; i
++)
1443 SET_REGNO_REG_SET (killed
, regno
+ i
);
1447 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1448 it checks whether this will not clobber the registers that are live on the
1449 edge (i.e. it requires liveness information to be up-to-date) and if there
1450 are some, then it tries to save and restore them. Returns true if
1453 safe_insert_insn_on_edge (rtx insn
, edge e
)
1457 rtx save_regs
= NULL_RTX
;
1460 enum machine_mode mode
;
1461 reg_set_iterator rsi
;
1463 #ifdef AVOID_CCMODE_COPIES
1469 killed
= ALLOC_REG_SET (®_obstack
);
1471 for (x
= insn
; x
; x
= NEXT_INSN (x
))
1473 note_stores (PATTERN (x
), mark_killed_regs
, killed
);
1475 /* Mark all hard registers as killed. Register allocator/reload cannot
1476 cope with the situation when life range of hard register spans operation
1477 for that the appropriate register is needed, i.e. it would be unsafe to
1478 extend the life ranges of hard registers. */
1479 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
1480 if (!fixed_regs
[regno
]
1481 && !REGNO_PTR_FRAME_P (regno
))
1482 SET_REGNO_REG_SET (killed
, regno
);
1484 bitmap_and_into (killed
, e
->dest
->global_live_at_start
);
1486 EXECUTE_IF_SET_IN_REG_SET (killed
, 0, regno
, rsi
)
1488 mode
= regno
< FIRST_PSEUDO_REGISTER
1489 ? reg_raw_mode
[regno
]
1490 : GET_MODE (regno_reg_rtx
[regno
]);
1491 if (mode
== VOIDmode
)
1494 if (noccmode
&& mode
== CCmode
)
1497 save_regs
= alloc_EXPR_LIST (0,
1500 gen_raw_REG (mode
, regno
)),
1509 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1511 from
= XEXP (XEXP (x
, 0), 1);
1512 to
= XEXP (XEXP (x
, 0), 0);
1513 emit_move_insn (to
, from
);
1516 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1518 from
= XEXP (XEXP (x
, 0), 0);
1519 to
= XEXP (XEXP (x
, 0), 1);
1520 emit_move_insn (to
, from
);
1522 insn
= get_insns ();
1524 free_EXPR_LIST_list (&save_regs
);
1526 insert_insn_on_edge (insn
, e
);
1528 FREE_REG_SET (killed
);
1533 /* Update the CFG for the instructions queued on edge E. */
1536 commit_one_edge_insertion (edge e
, int watch_calls
)
1538 rtx before
= NULL_RTX
, after
= NULL_RTX
, insns
, tmp
, last
;
1539 basic_block bb
= NULL
;
1541 /* Pull the insns off the edge now since the edge might go away. */
1543 e
->insns
.r
= NULL_RTX
;
1545 /* Special case -- avoid inserting code between call and storing
1546 its return value. */
1547 if (watch_calls
&& (e
->flags
& EDGE_FALLTHRU
)
1548 && single_pred_p (e
->dest
)
1549 && e
->src
!= ENTRY_BLOCK_PTR
1550 && CALL_P (BB_END (e
->src
)))
1552 rtx next
= next_nonnote_insn (BB_END (e
->src
));
1554 after
= BB_HEAD (e
->dest
);
1555 /* The first insn after the call may be a stack pop, skip it. */
1557 && keep_with_call_p (next
))
1560 next
= next_nonnote_insn (next
);
1564 if (!before
&& !after
)
1566 /* Figure out where to put these things. If the destination has
1567 one predecessor, insert there. Except for the exit block. */
1568 if (single_pred_p (e
->dest
) && e
->dest
!= EXIT_BLOCK_PTR
)
1572 /* Get the location correct wrt a code label, and "nice" wrt
1573 a basic block note, and before everything else. */
1576 tmp
= NEXT_INSN (tmp
);
1577 if (NOTE_INSN_BASIC_BLOCK_P (tmp
))
1578 tmp
= NEXT_INSN (tmp
);
1581 && NOTE_LINE_NUMBER (tmp
) == NOTE_INSN_UNLIKELY_EXECUTED_CODE
)
1582 tmp
= NEXT_INSN (tmp
);
1583 if (tmp
== BB_HEAD (bb
))
1586 after
= PREV_INSN (tmp
);
1588 after
= get_last_insn ();
1591 /* If the source has one successor and the edge is not abnormal,
1592 insert there. Except for the entry block. */
1593 else if ((e
->flags
& EDGE_ABNORMAL
) == 0
1594 && single_succ_p (e
->src
)
1595 && e
->src
!= ENTRY_BLOCK_PTR
)
1599 /* It is possible to have a non-simple jump here. Consider a target
1600 where some forms of unconditional jumps clobber a register. This
1601 happens on the fr30 for example.
1603 We know this block has a single successor, so we can just emit
1604 the queued insns before the jump. */
1605 if (JUMP_P (BB_END (bb
)))
1606 for (before
= BB_END (bb
);
1607 NOTE_P (PREV_INSN (before
))
1608 && NOTE_LINE_NUMBER (PREV_INSN (before
)) ==
1609 NOTE_INSN_LOOP_BEG
; before
= PREV_INSN (before
))
1613 /* We'd better be fallthru, or we've lost track of
1615 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1617 after
= BB_END (bb
);
1620 /* Otherwise we must split the edge. */
1623 bb
= split_edge (e
);
1624 after
= BB_END (bb
);
1626 if (flag_reorder_blocks_and_partition
1627 && targetm
.have_named_sections
1628 && e
->src
!= ENTRY_BLOCK_PTR
1629 && BB_PARTITION (e
->src
) == BB_COLD_PARTITION
1630 && !(e
->flags
& EDGE_CROSSING
))
1632 rtx bb_note
, new_note
, cur_insn
;
1635 for (cur_insn
= BB_HEAD (bb
); cur_insn
!= NEXT_INSN (BB_END (bb
));
1636 cur_insn
= NEXT_INSN (cur_insn
))
1637 if (NOTE_P (cur_insn
)
1638 && NOTE_LINE_NUMBER (cur_insn
) == NOTE_INSN_BASIC_BLOCK
)
1644 new_note
= emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE
,
1646 NOTE_BASIC_BLOCK (new_note
) = bb
;
1647 if (JUMP_P (BB_END (bb
))
1648 && !any_condjump_p (BB_END (bb
))
1649 && (single_succ_edge (bb
)->flags
& EDGE_CROSSING
))
1650 REG_NOTES (BB_END (bb
)) = gen_rtx_EXPR_LIST
1651 (REG_CROSSING_JUMP
, NULL_RTX
, REG_NOTES (BB_END (bb
)));
1652 if (after
== bb_note
)
1658 /* Now that we've found the spot, do the insertion. */
1662 emit_insn_before_noloc (insns
, before
);
1663 last
= prev_nonnote_insn (before
);
1666 last
= emit_insn_after_noloc (insns
, after
);
1668 if (returnjump_p (last
))
1670 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1671 This is not currently a problem because this only happens
1672 for the (single) epilogue, which already has a fallthru edge
1675 e
= single_succ_edge (bb
);
1676 gcc_assert (e
->dest
== EXIT_BLOCK_PTR
1677 && single_succ_p (bb
) && (e
->flags
& EDGE_FALLTHRU
));
1679 e
->flags
&= ~EDGE_FALLTHRU
;
1680 emit_barrier_after (last
);
1683 delete_insn (before
);
1686 gcc_assert (!JUMP_P (last
));
1688 /* Mark the basic block for find_many_sub_basic_blocks. */
1692 /* Update the CFG for all queued instructions. */
1695 commit_edge_insertions (void)
1699 bool changed
= false;
1701 #ifdef ENABLE_CHECKING
1702 verify_flow_info ();
1705 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1710 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1714 commit_one_edge_insertion (e
, false);
1721 blocks
= sbitmap_alloc (last_basic_block
);
1722 sbitmap_zero (blocks
);
1726 SET_BIT (blocks
, bb
->index
);
1727 /* Check for forgotten bb->aux values before commit_edge_insertions
1729 gcc_assert (bb
->aux
== &bb
->aux
);
1732 find_many_sub_basic_blocks (blocks
);
1733 sbitmap_free (blocks
);
1736 /* Update the CFG for all queued instructions, taking special care of inserting
1737 code on edges between call and storing its return value. */
1740 commit_edge_insertions_watch_calls (void)
1744 bool changed
= false;
1746 #ifdef ENABLE_CHECKING
1747 verify_flow_info ();
1750 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1755 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1759 commit_one_edge_insertion (e
, true);
1766 blocks
= sbitmap_alloc (last_basic_block
);
1767 sbitmap_zero (blocks
);
1771 SET_BIT (blocks
, bb
->index
);
1772 /* Check for forgotten bb->aux values before commit_edge_insertions
1774 gcc_assert (bb
->aux
== &bb
->aux
);
1777 find_many_sub_basic_blocks (blocks
);
1778 sbitmap_free (blocks
);
1781 /* Print out RTL-specific basic block information (live information
1782 at start and end). */
1785 rtl_dump_bb (basic_block bb
, FILE *outf
, int indent
)
1791 s_indent
= alloca ((size_t) indent
+ 1);
1792 memset (s_indent
, ' ', (size_t) indent
);
1793 s_indent
[indent
] = '\0';
1795 fprintf (outf
, ";;%s Registers live at start: ", s_indent
);
1796 dump_regset (bb
->global_live_at_start
, outf
);
1799 for (insn
= BB_HEAD (bb
), last
= NEXT_INSN (BB_END (bb
)); insn
!= last
;
1800 insn
= NEXT_INSN (insn
))
1801 print_rtl_single (outf
, insn
);
1803 fprintf (outf
, ";;%s Registers live at end: ", s_indent
);
1804 dump_regset (bb
->global_live_at_end
, outf
);
1808 /* Like print_rtl, but also print out live information for the start of each
1812 print_rtl_with_bb (FILE *outf
, rtx rtx_first
)
1817 fprintf (outf
, "(nil)\n");
1820 enum bb_state
{ NOT_IN_BB
, IN_ONE_BB
, IN_MULTIPLE_BB
};
1821 int max_uid
= get_max_uid ();
1822 basic_block
*start
= xcalloc (max_uid
, sizeof (basic_block
));
1823 basic_block
*end
= xcalloc (max_uid
, sizeof (basic_block
));
1824 enum bb_state
*in_bb_p
= xcalloc (max_uid
, sizeof (enum bb_state
));
1828 FOR_EACH_BB_REVERSE (bb
)
1832 start
[INSN_UID (BB_HEAD (bb
))] = bb
;
1833 end
[INSN_UID (BB_END (bb
))] = bb
;
1834 for (x
= BB_HEAD (bb
); x
!= NULL_RTX
; x
= NEXT_INSN (x
))
1836 enum bb_state state
= IN_MULTIPLE_BB
;
1838 if (in_bb_p
[INSN_UID (x
)] == NOT_IN_BB
)
1840 in_bb_p
[INSN_UID (x
)] = state
;
1842 if (x
== BB_END (bb
))
1847 for (tmp_rtx
= rtx_first
; NULL
!= tmp_rtx
; tmp_rtx
= NEXT_INSN (tmp_rtx
))
1851 if ((bb
= start
[INSN_UID (tmp_rtx
)]) != NULL
)
1853 fprintf (outf
, ";; Start of basic block %d, registers live:",
1855 dump_regset (bb
->global_live_at_start
, outf
);
1859 if (in_bb_p
[INSN_UID (tmp_rtx
)] == NOT_IN_BB
1860 && !NOTE_P (tmp_rtx
)
1861 && !BARRIER_P (tmp_rtx
))
1862 fprintf (outf
, ";; Insn is not within a basic block\n");
1863 else if (in_bb_p
[INSN_UID (tmp_rtx
)] == IN_MULTIPLE_BB
)
1864 fprintf (outf
, ";; Insn is in multiple basic blocks\n");
1866 did_output
= print_rtl_single (outf
, tmp_rtx
);
1868 if ((bb
= end
[INSN_UID (tmp_rtx
)]) != NULL
)
1870 fprintf (outf
, ";; End of basic block %d, registers live:\n",
1872 dump_regset (bb
->global_live_at_end
, outf
);
1885 if (current_function_epilogue_delay_list
!= 0)
1887 fprintf (outf
, "\n;; Insns in epilogue delay list:\n\n");
1888 for (tmp_rtx
= current_function_epilogue_delay_list
; tmp_rtx
!= 0;
1889 tmp_rtx
= XEXP (tmp_rtx
, 1))
1890 print_rtl_single (outf
, XEXP (tmp_rtx
, 0));
1895 update_br_prob_note (basic_block bb
)
1898 if (!JUMP_P (BB_END (bb
)))
1900 note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
);
1901 if (!note
|| INTVAL (XEXP (note
, 0)) == BRANCH_EDGE (bb
)->probability
)
1903 XEXP (note
, 0) = GEN_INT (BRANCH_EDGE (bb
)->probability
);
1906 /* Verify the CFG and RTL consistency common for both underlying RTL and
1909 Currently it does following checks:
1911 - test head/end pointers
1912 - overlapping of basic blocks
1913 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1914 - tails of basic blocks (ensure that boundary is necessary)
1915 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1916 and NOTE_INSN_BASIC_BLOCK
1917 - verify that no fall_thru edge crosses hot/cold partition boundaries
1919 In future it can be extended check a lot of other stuff as well
1920 (reachability of basic blocks, life information, etc. etc.). */
1923 rtl_verify_flow_info_1 (void)
1925 const int max_uid
= get_max_uid ();
1926 rtx last_head
= get_last_insn ();
1927 basic_block
*bb_info
;
1932 bb_info
= xcalloc (max_uid
, sizeof (basic_block
));
1934 FOR_EACH_BB_REVERSE (bb
)
1936 rtx head
= BB_HEAD (bb
);
1937 rtx end
= BB_END (bb
);
1939 /* Verify the end of the basic block is in the INSN chain. */
1940 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1946 error ("end insn %d for block %d not found in the insn stream",
1947 INSN_UID (end
), bb
->index
);
1951 /* Work backwards from the end to the head of the basic block
1952 to verify the head is in the RTL chain. */
1953 for (; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1955 /* While walking over the insn chain, verify insns appear
1956 in only one basic block and initialize the BB_INFO array
1957 used by other passes. */
1958 if (bb_info
[INSN_UID (x
)] != NULL
)
1960 error ("insn %d is in multiple basic blocks (%d and %d)",
1961 INSN_UID (x
), bb
->index
, bb_info
[INSN_UID (x
)]->index
);
1965 bb_info
[INSN_UID (x
)] = bb
;
1972 error ("head insn %d for block %d not found in the insn stream",
1973 INSN_UID (head
), bb
->index
);
1980 /* Now check the basic blocks (boundaries etc.) */
1981 FOR_EACH_BB_REVERSE (bb
)
1983 int n_fallthru
= 0, n_eh
= 0, n_call
= 0, n_abnormal
= 0, n_branch
= 0;
1984 edge e
, fallthru
= NULL
;
1988 if (JUMP_P (BB_END (bb
))
1989 && (note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
))
1990 && EDGE_COUNT (bb
->succs
) >= 2
1991 && any_condjump_p (BB_END (bb
)))
1993 if (INTVAL (XEXP (note
, 0)) != BRANCH_EDGE (bb
)->probability
1994 && profile_status
!= PROFILE_ABSENT
)
1996 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1997 INTVAL (XEXP (note
, 0)), BRANCH_EDGE (bb
)->probability
);
2001 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2003 if (e
->flags
& EDGE_FALLTHRU
)
2005 n_fallthru
++, fallthru
= e
;
2006 if ((e
->flags
& EDGE_CROSSING
)
2007 || (BB_PARTITION (e
->src
) != BB_PARTITION (e
->dest
)
2008 && e
->src
!= ENTRY_BLOCK_PTR
2009 && e
->dest
!= EXIT_BLOCK_PTR
))
2011 error ("Fallthru edge crosses section boundary (bb %i)",
2017 if ((e
->flags
& ~(EDGE_DFS_BACK
2019 | EDGE_IRREDUCIBLE_LOOP
2021 | EDGE_CROSSING
)) == 0)
2024 if (e
->flags
& EDGE_ABNORMAL_CALL
)
2027 if (e
->flags
& EDGE_EH
)
2029 else if (e
->flags
& EDGE_ABNORMAL
)
2033 if (n_eh
&& GET_CODE (PATTERN (BB_END (bb
))) != RESX
2034 && !find_reg_note (BB_END (bb
), REG_EH_REGION
, NULL_RTX
))
2036 error ("Missing REG_EH_REGION note in the end of bb %i", bb
->index
);
2040 && (!JUMP_P (BB_END (bb
))
2041 || (n_branch
> 1 && (any_uncondjump_p (BB_END (bb
))
2042 || any_condjump_p (BB_END (bb
))))))
2044 error ("Too many outgoing branch edges from bb %i", bb
->index
);
2047 if (n_fallthru
&& any_uncondjump_p (BB_END (bb
)))
2049 error ("Fallthru edge after unconditional jump %i", bb
->index
);
2052 if (n_branch
!= 1 && any_uncondjump_p (BB_END (bb
)))
2054 error ("Wrong amount of branch edges after unconditional jump %i", bb
->index
);
2057 if (n_branch
!= 1 && any_condjump_p (BB_END (bb
))
2058 && JUMP_LABEL (BB_END (bb
)) != BB_HEAD (fallthru
->dest
))
2060 error ("Wrong amount of branch edges after conditional jump %i", bb
->index
);
2063 if (n_call
&& !CALL_P (BB_END (bb
)))
2065 error ("Call edges for non-call insn in bb %i", bb
->index
);
2069 && (!CALL_P (BB_END (bb
)) && n_call
!= n_abnormal
)
2070 && (!JUMP_P (BB_END (bb
))
2071 || any_condjump_p (BB_END (bb
))
2072 || any_uncondjump_p (BB_END (bb
))))
2074 error ("Abnormal edges for no purpose in bb %i", bb
->index
);
2078 for (x
= BB_HEAD (bb
); x
!= NEXT_INSN (BB_END (bb
)); x
= NEXT_INSN (x
))
2079 /* We may have a barrier inside a basic block before dead code
2080 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2081 if (!BARRIER_P (x
) && BLOCK_FOR_INSN (x
) != bb
)
2084 if (! BLOCK_FOR_INSN (x
))
2086 ("insn %d inside basic block %d but block_for_insn is NULL",
2087 INSN_UID (x
), bb
->index
);
2090 ("insn %d inside basic block %d but block_for_insn is %i",
2091 INSN_UID (x
), bb
->index
, BLOCK_FOR_INSN (x
)->index
);
2096 /* OK pointers are correct. Now check the header of basic
2097 block. It ought to contain optional CODE_LABEL followed
2098 by NOTE_BASIC_BLOCK. */
2102 if (BB_END (bb
) == x
)
2104 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2112 if (!NOTE_INSN_BASIC_BLOCK_P (x
) || NOTE_BASIC_BLOCK (x
) != bb
)
2114 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2119 if (BB_END (bb
) == x
)
2120 /* Do checks for empty blocks here. */
2123 for (x
= NEXT_INSN (x
); x
; x
= NEXT_INSN (x
))
2125 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2127 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2128 INSN_UID (x
), bb
->index
);
2132 if (x
== BB_END (bb
))
2135 if (control_flow_insn_p (x
))
2137 error ("in basic block %d:", bb
->index
);
2138 fatal_insn ("flow control insn inside a basic block", x
);
2148 /* Verify the CFG and RTL consistency common for both underlying RTL and
2151 Currently it does following checks:
2152 - all checks of rtl_verify_flow_info_1
2153 - check that all insns are in the basic blocks
2154 (except the switch handling code, barriers and notes)
2155 - check that all returns are followed by barriers
2156 - check that all fallthru edge points to the adjacent blocks. */
2158 rtl_verify_flow_info (void)
2161 int err
= rtl_verify_flow_info_1 ();
2164 const rtx rtx_first
= get_insns ();
2165 basic_block last_bb_seen
= ENTRY_BLOCK_PTR
, curr_bb
= NULL
;
2167 FOR_EACH_BB_REVERSE (bb
)
2172 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2173 if (e
->flags
& EDGE_FALLTHRU
)
2179 /* Ensure existence of barrier in BB with no fallthru edges. */
2180 for (insn
= BB_END (bb
); !insn
|| !BARRIER_P (insn
);
2181 insn
= NEXT_INSN (insn
))
2184 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BASIC_BLOCK
))
2186 error ("missing barrier after block %i", bb
->index
);
2191 else if (e
->src
!= ENTRY_BLOCK_PTR
2192 && e
->dest
!= EXIT_BLOCK_PTR
)
2196 if (e
->src
->next_bb
!= e
->dest
)
2199 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2200 e
->src
->index
, e
->dest
->index
);
2204 for (insn
= NEXT_INSN (BB_END (e
->src
)); insn
!= BB_HEAD (e
->dest
);
2205 insn
= NEXT_INSN (insn
))
2206 if (BARRIER_P (insn
) || INSN_P (insn
))
2208 error ("verify_flow_info: Incorrect fallthru %i->%i",
2209 e
->src
->index
, e
->dest
->index
);
2210 fatal_insn ("wrong insn in the fallthru edge", insn
);
2217 last_bb_seen
= ENTRY_BLOCK_PTR
;
2219 for (x
= rtx_first
; x
; x
= NEXT_INSN (x
))
2221 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2223 bb
= NOTE_BASIC_BLOCK (x
);
2226 if (bb
!= last_bb_seen
->next_bb
)
2227 internal_error ("basic blocks not laid down consecutively");
2229 curr_bb
= last_bb_seen
= bb
;
2234 switch (GET_CODE (x
))
2241 /* An addr_vec is placed outside any basic block. */
2243 && JUMP_P (NEXT_INSN (x
))
2244 && (GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_DIFF_VEC
2245 || GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_VEC
))
2248 /* But in any case, non-deletable labels can appear anywhere. */
2252 fatal_insn ("insn outside basic block", x
);
2257 && returnjump_p (x
) && ! condjump_p (x
)
2258 && ! (NEXT_INSN (x
) && BARRIER_P (NEXT_INSN (x
))))
2259 fatal_insn ("return not followed by barrier", x
);
2260 if (curr_bb
&& x
== BB_END (curr_bb
))
2264 if (num_bb_notes
!= n_basic_blocks
)
2266 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2267 num_bb_notes
, n_basic_blocks
);
2272 /* Assume that the preceding pass has possibly eliminated jump instructions
2273 or converted the unconditional jumps. Eliminate the edges from CFG.
2274 Return true if any edges are eliminated. */
2277 purge_dead_edges (basic_block bb
)
2280 rtx insn
= BB_END (bb
), note
;
2281 bool purged
= false;
2285 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2286 if (NONJUMP_INSN_P (insn
)
2287 && (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
)))
2291 if (! may_trap_p (PATTERN (insn
))
2292 || ((eqnote
= find_reg_equal_equiv_note (insn
))
2293 && ! may_trap_p (XEXP (eqnote
, 0))))
2294 remove_note (insn
, note
);
2297 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2298 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2300 if (e
->flags
& EDGE_EH
)
2302 if (can_throw_internal (BB_END (bb
)))
2308 else if (e
->flags
& EDGE_ABNORMAL_CALL
)
2310 if (CALL_P (BB_END (bb
))
2311 && (! (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
))
2312 || INTVAL (XEXP (note
, 0)) >= 0))
2325 bb
->flags
|= BB_DIRTY
;
2335 /* We do care only about conditional jumps and simplejumps. */
2336 if (!any_condjump_p (insn
)
2337 && !returnjump_p (insn
)
2338 && !simplejump_p (insn
))
2341 /* Branch probability/prediction notes are defined only for
2342 condjumps. We've possibly turned condjump into simplejump. */
2343 if (simplejump_p (insn
))
2345 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2347 remove_note (insn
, note
);
2348 while ((note
= find_reg_note (insn
, REG_BR_PRED
, NULL
)))
2349 remove_note (insn
, note
);
2352 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2354 /* Avoid abnormal flags to leak from computed jumps turned
2355 into simplejumps. */
2357 e
->flags
&= ~EDGE_ABNORMAL
;
2359 /* See if this edge is one we should keep. */
2360 if ((e
->flags
& EDGE_FALLTHRU
) && any_condjump_p (insn
))
2361 /* A conditional jump can fall through into the next
2362 block, so we should keep the edge. */
2367 else if (e
->dest
!= EXIT_BLOCK_PTR
2368 && BB_HEAD (e
->dest
) == JUMP_LABEL (insn
))
2369 /* If the destination block is the target of the jump,
2375 else if (e
->dest
== EXIT_BLOCK_PTR
&& returnjump_p (insn
))
2376 /* If the destination block is the exit block, and this
2377 instruction is a return, then keep the edge. */
2382 else if ((e
->flags
& EDGE_EH
) && can_throw_internal (insn
))
2383 /* Keep the edges that correspond to exceptions thrown by
2384 this instruction and rematerialize the EDGE_ABNORMAL
2385 flag we just cleared above. */
2387 e
->flags
|= EDGE_ABNORMAL
;
2392 /* We do not need this edge. */
2393 bb
->flags
|= BB_DIRTY
;
2398 if (EDGE_COUNT (bb
->succs
) == 0 || !purged
)
2402 fprintf (dump_file
, "Purged edges from bb %i\n", bb
->index
);
2407 /* Redistribute probabilities. */
2408 if (single_succ_p (bb
))
2410 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2411 single_succ_edge (bb
)->count
= bb
->count
;
2415 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2419 b
= BRANCH_EDGE (bb
);
2420 f
= FALLTHRU_EDGE (bb
);
2421 b
->probability
= INTVAL (XEXP (note
, 0));
2422 f
->probability
= REG_BR_PROB_BASE
- b
->probability
;
2423 b
->count
= bb
->count
* b
->probability
/ REG_BR_PROB_BASE
;
2424 f
->count
= bb
->count
* f
->probability
/ REG_BR_PROB_BASE
;
2429 else if (CALL_P (insn
) && SIBLING_CALL_P (insn
))
2431 /* First, there should not be any EH or ABCALL edges resulting
2432 from non-local gotos and the like. If there were, we shouldn't
2433 have created the sibcall in the first place. Second, there
2434 should of course never have been a fallthru edge. */
2435 gcc_assert (single_succ_p (bb
));
2436 gcc_assert (single_succ_edge (bb
)->flags
2437 == (EDGE_SIBCALL
| EDGE_ABNORMAL
));
2442 /* If we don't see a jump insn, we don't know exactly why the block would
2443 have been broken at this point. Look for a simple, non-fallthru edge,
2444 as these are only created by conditional branches. If we find such an
2445 edge we know that there used to be a jump here and can then safely
2446 remove all non-fallthru edges. */
2448 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2449 if (! (e
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
)))
2458 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2460 if (!(e
->flags
& EDGE_FALLTHRU
))
2462 bb
->flags
|= BB_DIRTY
;
2470 gcc_assert (single_succ_p (bb
));
2472 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2473 single_succ_edge (bb
)->count
= bb
->count
;
2476 fprintf (dump_file
, "Purged non-fallthru edges from bb %i\n",
2481 /* Search all basic blocks for potentially dead edges and purge them. Return
2482 true if some edge has been eliminated. */
2485 purge_all_dead_edges (int update_life_p
)
2493 blocks
= sbitmap_alloc (last_basic_block
);
2494 sbitmap_zero (blocks
);
2499 bool purged_here
= purge_dead_edges (bb
);
2501 purged
|= purged_here
;
2502 if (purged_here
&& update_life_p
)
2503 SET_BIT (blocks
, bb
->index
);
2506 if (update_life_p
&& purged
)
2507 update_life_info (blocks
, UPDATE_LIFE_GLOBAL
,
2508 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
2509 | PROP_KILL_DEAD_CODE
);
2512 sbitmap_free (blocks
);
2516 /* Same as split_block but update cfg_layout structures. */
2519 cfg_layout_split_block (basic_block bb
, void *insnp
)
2522 basic_block new_bb
= rtl_split_block (bb
, insn
);
2524 new_bb
->rbi
->footer
= bb
->rbi
->footer
;
2525 bb
->rbi
->footer
= NULL
;
2531 /* Redirect Edge to DEST. */
2533 cfg_layout_redirect_edge_and_branch (edge e
, basic_block dest
)
2535 basic_block src
= e
->src
;
2538 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
2541 if (e
->dest
== dest
)
2544 if (e
->src
!= ENTRY_BLOCK_PTR
2545 && (ret
= try_redirect_by_replacing_jump (e
, dest
, true)))
2547 src
->flags
|= BB_DIRTY
;
2551 if (e
->src
== ENTRY_BLOCK_PTR
2552 && (e
->flags
& EDGE_FALLTHRU
) && !(e
->flags
& EDGE_COMPLEX
))
2555 fprintf (dump_file
, "Redirecting entry edge from bb %i to %i\n",
2556 e
->src
->index
, dest
->index
);
2558 e
->src
->flags
|= BB_DIRTY
;
2559 redirect_edge_succ (e
, dest
);
2563 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2564 in the case the basic block appears to be in sequence. Avoid this
2567 if (e
->flags
& EDGE_FALLTHRU
)
2569 /* Redirect any branch edges unified with the fallthru one. */
2570 if (JUMP_P (BB_END (src
))
2571 && label_is_jump_target_p (BB_HEAD (e
->dest
),
2577 fprintf (dump_file
, "Fallthru edge unified with branch "
2578 "%i->%i redirected to %i\n",
2579 e
->src
->index
, e
->dest
->index
, dest
->index
);
2580 e
->flags
&= ~EDGE_FALLTHRU
;
2581 redirected
= redirect_branch_edge (e
, dest
);
2582 gcc_assert (redirected
);
2583 e
->flags
|= EDGE_FALLTHRU
;
2584 e
->src
->flags
|= BB_DIRTY
;
2587 /* In case we are redirecting fallthru edge to the branch edge
2588 of conditional jump, remove it. */
2589 if (EDGE_COUNT (src
->succs
) == 2)
2591 /* Find the edge that is different from E. */
2592 edge s
= EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
);
2595 && any_condjump_p (BB_END (src
))
2596 && onlyjump_p (BB_END (src
)))
2597 delete_insn (BB_END (src
));
2599 ret
= redirect_edge_succ_nodup (e
, dest
);
2601 fprintf (dump_file
, "Fallthru edge %i->%i redirected to %i\n",
2602 e
->src
->index
, e
->dest
->index
, dest
->index
);
2605 ret
= redirect_branch_edge (e
, dest
);
2607 /* We don't want simplejumps in the insn stream during cfglayout. */
2608 gcc_assert (!simplejump_p (BB_END (src
)));
2610 src
->flags
|= BB_DIRTY
;
2614 /* Simple wrapper as we always can redirect fallthru edges. */
2616 cfg_layout_redirect_edge_and_branch_force (edge e
, basic_block dest
)
2618 edge redirected
= cfg_layout_redirect_edge_and_branch (e
, dest
);
2620 gcc_assert (redirected
);
2624 /* Same as delete_basic_block but update cfg_layout structures. */
2627 cfg_layout_delete_block (basic_block bb
)
2629 rtx insn
, next
, prev
= PREV_INSN (BB_HEAD (bb
)), *to
, remaints
;
2631 if (bb
->rbi
->header
)
2633 next
= BB_HEAD (bb
);
2635 NEXT_INSN (prev
) = bb
->rbi
->header
;
2637 set_first_insn (bb
->rbi
->header
);
2638 PREV_INSN (bb
->rbi
->header
) = prev
;
2639 insn
= bb
->rbi
->header
;
2640 while (NEXT_INSN (insn
))
2641 insn
= NEXT_INSN (insn
);
2642 NEXT_INSN (insn
) = next
;
2643 PREV_INSN (next
) = insn
;
2645 next
= NEXT_INSN (BB_END (bb
));
2646 if (bb
->rbi
->footer
)
2648 insn
= bb
->rbi
->footer
;
2651 if (BARRIER_P (insn
))
2653 if (PREV_INSN (insn
))
2654 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
2656 bb
->rbi
->footer
= NEXT_INSN (insn
);
2657 if (NEXT_INSN (insn
))
2658 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
2662 insn
= NEXT_INSN (insn
);
2664 if (bb
->rbi
->footer
)
2667 NEXT_INSN (insn
) = bb
->rbi
->footer
;
2668 PREV_INSN (bb
->rbi
->footer
) = insn
;
2669 while (NEXT_INSN (insn
))
2670 insn
= NEXT_INSN (insn
);
2671 NEXT_INSN (insn
) = next
;
2673 PREV_INSN (next
) = insn
;
2675 set_last_insn (insn
);
2678 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2679 to
= &bb
->next_bb
->rbi
->header
;
2681 to
= &cfg_layout_function_footer
;
2682 rtl_delete_block (bb
);
2685 prev
= NEXT_INSN (prev
);
2687 prev
= get_insns ();
2689 next
= PREV_INSN (next
);
2691 next
= get_last_insn ();
2693 if (next
&& NEXT_INSN (next
) != prev
)
2695 remaints
= unlink_insn_chain (prev
, next
);
2697 while (NEXT_INSN (insn
))
2698 insn
= NEXT_INSN (insn
);
2699 NEXT_INSN (insn
) = *to
;
2701 PREV_INSN (*to
) = insn
;
2706 /* Return true when blocks A and B can be safely merged. */
2708 cfg_layout_can_merge_blocks_p (basic_block a
, basic_block b
)
2710 /* If we are partitioning hot/cold basic blocks, we don't want to
2711 mess up unconditional or indirect jumps that cross between hot
2714 Basic block partitioning may result in some jumps that appear to
2715 be optimizable (or blocks that appear to be mergeable), but which really
2716 must be left untouched (they are required to make it safely across
2717 partition boundaries). See the comments at the top of
2718 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2720 if (flag_reorder_blocks_and_partition
2721 && (find_reg_note (BB_END (a
), REG_CROSSING_JUMP
, NULL_RTX
)
2722 || find_reg_note (BB_END (b
), REG_CROSSING_JUMP
, NULL_RTX
)
2723 || BB_PARTITION (a
) != BB_PARTITION (b
)))
2726 /* There must be exactly one edge in between the blocks. */
2727 return (single_succ_p (a
)
2728 && single_succ (a
) == b
2729 && single_pred_p (b
) == 1
2731 /* Must be simple edge. */
2732 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
2733 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
2734 /* If the jump insn has side effects,
2735 we can't kill the edge. */
2736 && (!JUMP_P (BB_END (a
))
2737 || (reload_completed
2738 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
2741 /* Merge block A and B, abort when it is not possible. */
2743 cfg_layout_merge_blocks (basic_block a
, basic_block b
)
2745 #ifdef ENABLE_CHECKING
2746 gcc_assert (cfg_layout_can_merge_blocks_p (a
, b
));
2749 /* If there was a CODE_LABEL beginning B, delete it. */
2750 if (LABEL_P (BB_HEAD (b
)))
2751 delete_insn (BB_HEAD (b
));
2753 /* We should have fallthru edge in a, or we can do dummy redirection to get
2755 if (JUMP_P (BB_END (a
)))
2756 try_redirect_by_replacing_jump (EDGE_SUCC (a
, 0), b
, true);
2757 gcc_assert (!JUMP_P (BB_END (a
)));
2759 /* Possible line number notes should appear in between. */
2762 rtx first
= BB_END (a
), last
;
2764 last
= emit_insn_after_noloc (b
->rbi
->header
, BB_END (a
));
2765 delete_insn_chain (NEXT_INSN (first
), last
);
2766 b
->rbi
->header
= NULL
;
2769 /* In the case basic blocks are not adjacent, move them around. */
2770 if (NEXT_INSN (BB_END (a
)) != BB_HEAD (b
))
2772 rtx first
= unlink_insn_chain (BB_HEAD (b
), BB_END (b
));
2774 emit_insn_after_noloc (first
, BB_END (a
));
2775 /* Skip possible DELETED_LABEL insn. */
2776 if (!NOTE_INSN_BASIC_BLOCK_P (first
))
2777 first
= NEXT_INSN (first
);
2778 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first
));
2780 delete_insn (first
);
2782 /* Otherwise just re-associate the instructions. */
2787 for (insn
= BB_HEAD (b
);
2788 insn
!= NEXT_INSN (BB_END (b
));
2789 insn
= NEXT_INSN (insn
))
2790 set_block_for_insn (insn
, a
);
2792 /* Skip possible DELETED_LABEL insn. */
2793 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
2794 insn
= NEXT_INSN (insn
);
2795 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
2797 BB_END (a
) = BB_END (b
);
2801 /* Possible tablejumps and barriers should appear after the block. */
2804 if (!a
->rbi
->footer
)
2805 a
->rbi
->footer
= b
->rbi
->footer
;
2808 rtx last
= a
->rbi
->footer
;
2810 while (NEXT_INSN (last
))
2811 last
= NEXT_INSN (last
);
2812 NEXT_INSN (last
) = b
->rbi
->footer
;
2813 PREV_INSN (b
->rbi
->footer
) = last
;
2815 b
->rbi
->footer
= NULL
;
2819 fprintf (dump_file
, "Merged blocks %d and %d.\n",
2820 a
->index
, b
->index
);
2826 cfg_layout_split_edge (edge e
)
2828 basic_block new_bb
=
2829 create_basic_block (e
->src
!= ENTRY_BLOCK_PTR
2830 ? NEXT_INSN (BB_END (e
->src
)) : get_insns (),
2833 /* ??? This info is likely going to be out of date very soon, but we must
2834 create it to avoid getting an ICE later. */
2835 if (e
->dest
->global_live_at_start
)
2837 new_bb
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
2838 new_bb
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
2839 COPY_REG_SET (new_bb
->global_live_at_start
,
2840 e
->dest
->global_live_at_start
);
2841 COPY_REG_SET (new_bb
->global_live_at_end
,
2842 e
->dest
->global_live_at_start
);
2845 make_edge (new_bb
, e
->dest
, EDGE_FALLTHRU
);
2846 redirect_edge_and_branch_force (e
, new_bb
);
2851 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2854 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED
)
2858 /* Return 1 if BB ends with a call, possibly followed by some
2859 instructions that must stay with the call, 0 otherwise. */
2862 rtl_block_ends_with_call_p (basic_block bb
)
2864 rtx insn
= BB_END (bb
);
2866 while (!CALL_P (insn
)
2867 && insn
!= BB_HEAD (bb
)
2868 && keep_with_call_p (insn
))
2869 insn
= PREV_INSN (insn
);
2870 return (CALL_P (insn
));
2873 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2876 rtl_block_ends_with_condjump_p (basic_block bb
)
2878 return any_condjump_p (BB_END (bb
));
2881 /* Return true if we need to add fake edge to exit.
2882 Helper function for rtl_flow_call_edges_add. */
2885 need_fake_edge_p (rtx insn
)
2891 && !SIBLING_CALL_P (insn
)
2892 && !find_reg_note (insn
, REG_NORETURN
, NULL
)
2893 && !CONST_OR_PURE_CALL_P (insn
)))
2896 return ((GET_CODE (PATTERN (insn
)) == ASM_OPERANDS
2897 && MEM_VOLATILE_P (PATTERN (insn
)))
2898 || (GET_CODE (PATTERN (insn
)) == PARALLEL
2899 && asm_noperands (insn
) != -1
2900 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn
), 0, 0)))
2901 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
);
2904 /* Add fake edges to the function exit for any non constant and non noreturn
2905 calls, volatile inline assembly in the bitmap of blocks specified by
2906 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2909 The goal is to expose cases in which entering a basic block does not imply
2910 that all subsequent instructions must be executed. */
2913 rtl_flow_call_edges_add (sbitmap blocks
)
2916 int blocks_split
= 0;
2917 int last_bb
= last_basic_block
;
2918 bool check_last_block
= false;
2920 if (n_basic_blocks
== 0)
2924 check_last_block
= true;
2926 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
2928 /* In the last basic block, before epilogue generation, there will be
2929 a fallthru edge to EXIT. Special care is required if the last insn
2930 of the last basic block is a call because make_edge folds duplicate
2931 edges, which would result in the fallthru edge also being marked
2932 fake, which would result in the fallthru edge being removed by
2933 remove_fake_edges, which would result in an invalid CFG.
2935 Moreover, we can't elide the outgoing fake edge, since the block
2936 profiler needs to take this into account in order to solve the minimal
2937 spanning tree in the case that the call doesn't return.
2939 Handle this by adding a dummy instruction in a new last basic block. */
2940 if (check_last_block
)
2942 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
2943 rtx insn
= BB_END (bb
);
2945 /* Back up past insns that must be kept in the same block as a call. */
2946 while (insn
!= BB_HEAD (bb
)
2947 && keep_with_call_p (insn
))
2948 insn
= PREV_INSN (insn
);
2950 if (need_fake_edge_p (insn
))
2954 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
2957 insert_insn_on_edge (gen_rtx_USE (VOIDmode
, const0_rtx
), e
);
2958 commit_edge_insertions ();
2963 /* Now add fake edges to the function exit for any non constant
2964 calls since there is no way that we can determine if they will
2967 for (i
= 0; i
< last_bb
; i
++)
2969 basic_block bb
= BASIC_BLOCK (i
);
2976 if (blocks
&& !TEST_BIT (blocks
, i
))
2979 for (insn
= BB_END (bb
); ; insn
= prev_insn
)
2981 prev_insn
= PREV_INSN (insn
);
2982 if (need_fake_edge_p (insn
))
2985 rtx split_at_insn
= insn
;
2987 /* Don't split the block between a call and an insn that should
2988 remain in the same block as the call. */
2990 while (split_at_insn
!= BB_END (bb
)
2991 && keep_with_call_p (NEXT_INSN (split_at_insn
)))
2992 split_at_insn
= NEXT_INSN (split_at_insn
);
2994 /* The handling above of the final block before the epilogue
2995 should be enough to verify that there is no edge to the exit
2996 block in CFG already. Calling make_edge in such case would
2997 cause us to mark that edge as fake and remove it later. */
2999 #ifdef ENABLE_CHECKING
3000 if (split_at_insn
== BB_END (bb
))
3002 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
3003 gcc_assert (e
== NULL
);
3007 /* Note that the following may create a new basic block
3008 and renumber the existing basic blocks. */
3009 if (split_at_insn
!= BB_END (bb
))
3011 e
= split_block (bb
, split_at_insn
);
3016 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
3019 if (insn
== BB_HEAD (bb
))
3025 verify_flow_info ();
3027 return blocks_split
;
3030 /* Implementation of CFG manipulation for linearized RTL. */
3031 struct cfg_hooks rtl_cfg_hooks
= {
3033 rtl_verify_flow_info
,
3035 rtl_create_basic_block
,
3036 rtl_redirect_edge_and_branch
,
3037 rtl_redirect_edge_and_branch_force
,
3040 rtl_move_block_after
,
3041 rtl_can_merge_blocks
, /* can_merge_blocks_p */
3045 NULL
, /* can_duplicate_block_p */
3046 NULL
, /* duplicate_block */
3048 rtl_make_forwarder_block
,
3049 rtl_tidy_fallthru_edge
,
3050 rtl_block_ends_with_call_p
,
3051 rtl_block_ends_with_condjump_p
,
3052 rtl_flow_call_edges_add
,
3053 NULL
, /* execute_on_growing_pred */
3054 NULL
/* execute_on_shrinking_pred */
3057 /* Implementation of CFG manipulation for cfg layout RTL, where
3058 basic block connected via fallthru edges does not have to be adjacent.
3059 This representation will hopefully become the default one in future
3060 version of the compiler. */
3062 /* We do not want to declare these functions in a header file, since they
3063 should only be used through the cfghooks interface, and we do not want to
3064 move them here since it would require also moving quite a lot of related
3066 extern bool cfg_layout_can_duplicate_bb_p (basic_block
);
3067 extern basic_block
cfg_layout_duplicate_bb (basic_block
);
3069 struct cfg_hooks cfg_layout_rtl_cfg_hooks
= {
3071 rtl_verify_flow_info_1
,
3073 cfg_layout_create_basic_block
,
3074 cfg_layout_redirect_edge_and_branch
,
3075 cfg_layout_redirect_edge_and_branch_force
,
3076 cfg_layout_delete_block
,
3077 cfg_layout_split_block
,
3078 rtl_move_block_after
,
3079 cfg_layout_can_merge_blocks_p
,
3080 cfg_layout_merge_blocks
,
3083 cfg_layout_can_duplicate_bb_p
,
3084 cfg_layout_duplicate_bb
,
3085 cfg_layout_split_edge
,
3086 rtl_make_forwarder_block
,
3088 rtl_block_ends_with_call_p
,
3089 rtl_block_ends_with_condjump_p
,
3090 rtl_flow_call_edges_add
,
3091 NULL
, /* execute_on_growing_pred */
3092 NULL
/* execute_on_shrinking_pred */