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, 51 Franklin Street, Fifth Floor, 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 #include "tree-pass.h"
64 static int can_delete_note_p (rtx
);
65 static int can_delete_label_p (rtx
);
66 static void commit_one_edge_insertion (edge
, int);
67 static rtx
last_loop_beg_note (rtx
);
68 static bool back_edge_of_syntactic_loop_p (basic_block
, basic_block
);
69 static basic_block
rtl_split_edge (edge
);
70 static bool rtl_move_block_after (basic_block
, basic_block
);
71 static int rtl_verify_flow_info (void);
72 static basic_block
cfg_layout_split_block (basic_block
, void *);
73 static edge
cfg_layout_redirect_edge_and_branch (edge
, basic_block
);
74 static basic_block
cfg_layout_redirect_edge_and_branch_force (edge
, basic_block
);
75 static void cfg_layout_delete_block (basic_block
);
76 static void rtl_delete_block (basic_block
);
77 static basic_block
rtl_redirect_edge_and_branch_force (edge
, basic_block
);
78 static edge
rtl_redirect_edge_and_branch (edge
, basic_block
);
79 static basic_block
rtl_split_block (basic_block
, void *);
80 static void rtl_dump_bb (basic_block
, FILE *, int);
81 static int rtl_verify_flow_info_1 (void);
82 static void mark_killed_regs (rtx
, rtx
, void *);
83 static void rtl_make_forwarder_block (edge
);
85 /* Return true if NOTE is not one of the ones that must be kept paired,
86 so that we may simply delete it. */
89 can_delete_note_p (rtx note
)
91 return (NOTE_LINE_NUMBER (note
) == NOTE_INSN_DELETED
92 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_BASIC_BLOCK
);
95 /* True if a given label can be deleted. */
98 can_delete_label_p (rtx label
)
100 return (!LABEL_PRESERVE_P (label
)
101 /* User declared labels must be preserved. */
102 && LABEL_NAME (label
) == 0
103 && !in_expr_list_p (forced_labels
, label
));
106 /* Delete INSN by patching it out. Return the next insn. */
109 delete_insn (rtx insn
)
111 rtx next
= NEXT_INSN (insn
);
113 bool really_delete
= true;
117 /* Some labels can't be directly removed from the INSN chain, as they
118 might be references via variables, constant pool etc.
119 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
120 if (! can_delete_label_p (insn
))
122 const char *name
= LABEL_NAME (insn
);
124 really_delete
= false;
125 PUT_CODE (insn
, NOTE
);
126 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
127 NOTE_DELETED_LABEL_NAME (insn
) = name
;
130 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
135 /* If this insn has already been deleted, something is very wrong. */
136 gcc_assert (!INSN_DELETED_P (insn
));
138 INSN_DELETED_P (insn
) = 1;
141 /* If deleting a jump, decrement the use count of the label. Deleting
142 the label itself should happen in the normal course of block merging. */
145 && LABEL_P (JUMP_LABEL (insn
)))
146 LABEL_NUSES (JUMP_LABEL (insn
))--;
148 /* Also if deleting an insn that references a label. */
151 while ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)) != NULL_RTX
152 && LABEL_P (XEXP (note
, 0)))
154 LABEL_NUSES (XEXP (note
, 0))--;
155 remove_note (insn
, note
);
160 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
161 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
163 rtx pat
= PATTERN (insn
);
164 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
165 int len
= XVECLEN (pat
, diff_vec_p
);
168 for (i
= 0; i
< len
; i
++)
170 rtx label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
172 /* When deleting code in bulk (e.g. removing many unreachable
173 blocks) we can delete a label that's a target of the vector
174 before deleting the vector itself. */
176 LABEL_NUSES (label
)--;
183 /* Like delete_insn but also purge dead edges from BB. */
185 delete_insn_and_edges (rtx insn
)
191 && BLOCK_FOR_INSN (insn
)
192 && BB_END (BLOCK_FOR_INSN (insn
)) == insn
)
194 x
= delete_insn (insn
);
196 purge_dead_edges (BLOCK_FOR_INSN (insn
));
200 /* Unlink a chain of insns between START and FINISH, leaving notes
201 that must be paired. */
204 delete_insn_chain (rtx start
, rtx finish
)
208 /* Unchain the insns one by one. It would be quicker to delete all of these
209 with a single unchaining, rather than one at a time, but we need to keep
213 next
= NEXT_INSN (start
);
214 if (NOTE_P (start
) && !can_delete_note_p (start
))
217 next
= delete_insn (start
);
225 /* Like delete_insn but also purge dead edges from BB. */
227 delete_insn_chain_and_edges (rtx first
, rtx last
)
232 && BLOCK_FOR_INSN (last
)
233 && BB_END (BLOCK_FOR_INSN (last
)) == last
)
235 delete_insn_chain (first
, last
);
237 purge_dead_edges (BLOCK_FOR_INSN (last
));
240 /* Create a new basic block consisting of the instructions between HEAD and END
241 inclusive. This function is designed to allow fast BB construction - reuses
242 the note and basic block struct in BB_NOTE, if any and do not grow
243 BASIC_BLOCK chain and should be used directly only by CFG construction code.
244 END can be NULL in to create new empty basic block before HEAD. Both END
245 and HEAD can be NULL to create basic block at the end of INSN chain.
246 AFTER is the basic block we should be put after. */
249 create_basic_block_structure (rtx head
, rtx end
, rtx bb_note
, basic_block after
)
254 && (bb
= NOTE_BASIC_BLOCK (bb_note
)) != NULL
257 /* If we found an existing note, thread it back onto the chain. */
265 after
= PREV_INSN (head
);
269 if (after
!= bb_note
&& NEXT_INSN (after
) != bb_note
)
270 reorder_insns_nobb (bb_note
, bb_note
, after
);
274 /* Otherwise we must create a note and a basic block structure. */
278 init_rtl_bb_info (bb
);
281 = emit_note_after (NOTE_INSN_BASIC_BLOCK
, get_last_insn ());
282 else if (LABEL_P (head
) && end
)
284 bb_note
= emit_note_after (NOTE_INSN_BASIC_BLOCK
, head
);
290 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
, head
);
296 NOTE_BASIC_BLOCK (bb_note
) = bb
;
299 /* Always include the bb note in the block. */
300 if (NEXT_INSN (end
) == bb_note
)
305 bb
->index
= last_basic_block
++;
306 bb
->flags
= BB_NEW
| BB_RTL
;
307 link_block (bb
, after
);
308 SET_BASIC_BLOCK (bb
->index
, bb
);
309 update_bb_for_insn (bb
);
310 BB_SET_PARTITION (bb
, BB_UNPARTITIONED
);
312 /* Tag the block so that we know it has been used when considering
313 other basic block notes. */
319 /* Create new basic block consisting of instructions in between HEAD and END
320 and place it to the BB chain after block AFTER. END can be NULL in to
321 create new empty basic block before HEAD. Both END and HEAD can be NULL to
322 create basic block at the end of INSN chain. */
325 rtl_create_basic_block (void *headp
, void *endp
, basic_block after
)
327 rtx head
= headp
, end
= endp
;
330 /* Grow the basic block array if needed. */
331 if ((size_t) last_basic_block
>= VEC_length (basic_block
, basic_block_info
))
333 size_t old_size
= VEC_length (basic_block
, basic_block_info
);
334 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
336 VEC_safe_grow (basic_block
, gc
, basic_block_info
, new_size
);
337 p
= VEC_address (basic_block
, basic_block_info
);
338 memset (&p
[old_size
], 0, sizeof (basic_block
) * (new_size
- old_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
);
356 /* Delete the insns in a (non-live) block. We physically delete every
357 non-deleted-note insn, and update the flow graph appropriately.
359 Return nonzero if we deleted an exception handler. */
361 /* ??? Preserving all such notes strikes me as wrong. It would be nice
362 to post-process the stream to remove empty blocks, loops, ranges, etc. */
365 rtl_delete_block (basic_block b
)
369 /* If the head of this block is a CODE_LABEL, then it might be the
370 label for an exception handler which can't be reached. We need
371 to remove the label from the exception_handler_label list. */
374 maybe_remove_eh_handler (insn
);
376 /* Include any jump table following the basic block. */
378 if (tablejump_p (end
, NULL
, &tmp
))
381 /* Include any barriers that may follow the basic block. */
382 tmp
= next_nonnote_insn (end
);
383 while (tmp
&& BARRIER_P (tmp
))
386 tmp
= next_nonnote_insn (end
);
389 /* Selectively delete the entire chain. */
391 delete_insn_chain (insn
, end
);
394 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
397 compute_bb_for_insn (void)
403 rtx end
= BB_END (bb
);
406 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
408 BLOCK_FOR_INSN (insn
) = bb
;
415 /* Release the basic_block_for_insn array. */
418 free_bb_for_insn (void)
421 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
422 if (!BARRIER_P (insn
))
423 BLOCK_FOR_INSN (insn
) = NULL
;
426 struct tree_opt_pass pass_free_cfg
=
430 free_bb_for_insn
, /* execute */
433 0, /* static_pass_number */
435 0, /* properties_required */
436 0, /* properties_provided */
437 PROP_cfg
, /* properties_destroyed */
438 0, /* todo_flags_start */
439 0, /* todo_flags_finish */
443 /* Return RTX to emit after when we want to emit code on the entry of function. */
445 entry_of_function (void)
447 return (n_basic_blocks
> NUM_FIXED_BLOCKS
?
448 BB_HEAD (ENTRY_BLOCK_PTR
->next_bb
) : get_insns ());
451 /* Update insns block within BB. */
454 update_bb_for_insn (basic_block bb
)
458 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
460 if (!BARRIER_P (insn
))
461 set_block_for_insn (insn
, bb
);
462 if (insn
== BB_END (bb
))
467 /* Creates a new basic block just after basic block B by splitting
468 everything after specified instruction I. */
471 rtl_split_block (basic_block bb
, void *insnp
)
480 insn
= first_insn_after_basic_block_note (bb
);
483 insn
= PREV_INSN (insn
);
485 insn
= get_last_insn ();
488 /* We probably should check type of the insn so that we do not create
489 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
491 if (insn
== BB_END (bb
))
492 emit_note_after (NOTE_INSN_DELETED
, insn
);
494 /* Create the new basic block. */
495 new_bb
= create_basic_block (NEXT_INSN (insn
), BB_END (bb
), bb
);
496 BB_COPY_PARTITION (new_bb
, bb
);
499 /* Redirect the outgoing edges. */
500 new_bb
->succs
= bb
->succs
;
502 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
505 if (bb
->il
.rtl
->global_live_at_start
)
507 new_bb
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
508 new_bb
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
509 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_end
, bb
->il
.rtl
->global_live_at_end
);
511 /* We now have to calculate which registers are live at the end
512 of the split basic block and at the start of the new basic
513 block. Start with those registers that are known to be live
514 at the end of the original basic block and get
515 propagate_block to determine which registers are live. */
516 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_start
, bb
->il
.rtl
->global_live_at_end
);
517 propagate_block (new_bb
, new_bb
->il
.rtl
->global_live_at_start
, NULL
, NULL
, 0);
518 COPY_REG_SET (bb
->il
.rtl
->global_live_at_end
,
519 new_bb
->il
.rtl
->global_live_at_start
);
520 #ifdef HAVE_conditional_execution
521 /* In the presence of conditional execution we are not able to update
522 liveness precisely. */
523 if (reload_completed
)
525 bb
->flags
|= BB_DIRTY
;
526 new_bb
->flags
|= BB_DIRTY
;
534 /* Blocks A and B are to be merged into a single block A. The insns
535 are already contiguous. */
538 rtl_merge_blocks (basic_block a
, basic_block b
)
540 rtx b_head
= BB_HEAD (b
), b_end
= BB_END (b
), a_end
= BB_END (a
);
541 rtx del_first
= NULL_RTX
, del_last
= NULL_RTX
;
544 /* If there was a CODE_LABEL beginning B, delete it. */
545 if (LABEL_P (b_head
))
547 /* This might have been an EH label that no longer has incoming
548 EH edges. Update data structures to match. */
549 maybe_remove_eh_handler (b_head
);
551 /* Detect basic blocks with nothing but a label. This can happen
552 in particular at the end of a function. */
556 del_first
= del_last
= b_head
;
557 b_head
= NEXT_INSN (b_head
);
560 /* Delete the basic block note and handle blocks containing just that
562 if (NOTE_INSN_BASIC_BLOCK_P (b_head
))
570 b_head
= NEXT_INSN (b_head
);
573 /* If there was a jump out of A, delete it. */
578 for (prev
= PREV_INSN (a_end
); ; prev
= PREV_INSN (prev
))
580 || NOTE_LINE_NUMBER (prev
) == NOTE_INSN_BASIC_BLOCK
581 || prev
== BB_HEAD (a
))
587 /* If this was a conditional jump, we need to also delete
588 the insn that set cc0. */
589 if (only_sets_cc0_p (prev
))
593 prev
= prev_nonnote_insn (prev
);
600 a_end
= PREV_INSN (del_first
);
602 else if (BARRIER_P (NEXT_INSN (a_end
)))
603 del_first
= NEXT_INSN (a_end
);
605 /* Delete everything marked above as well as crap that might be
606 hanging out between the two blocks. */
608 delete_insn_chain (del_first
, del_last
);
610 /* Reassociate the insns of B with A. */
615 for (x
= a_end
; x
!= b_end
; x
= NEXT_INSN (x
))
616 set_block_for_insn (x
, a
);
618 set_block_for_insn (b_end
, a
);
624 a
->il
.rtl
->global_live_at_end
= b
->il
.rtl
->global_live_at_end
;
627 /* Return true when block A and B can be merged. */
629 rtl_can_merge_blocks (basic_block a
,basic_block b
)
631 /* If we are partitioning hot/cold basic blocks, we don't want to
632 mess up unconditional or indirect jumps that cross between hot
635 Basic block partitioning may result in some jumps that appear to
636 be optimizable (or blocks that appear to be mergeable), but which really
637 must be left untouched (they are required to make it safely across
638 partition boundaries). See the comments at the top of
639 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
641 if (BB_PARTITION (a
) != BB_PARTITION (b
))
644 /* There must be exactly one edge in between the blocks. */
645 return (single_succ_p (a
)
646 && single_succ (a
) == b
649 /* Must be simple edge. */
650 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
652 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
653 /* If the jump insn has side effects,
654 we can't kill the edge. */
655 && (!JUMP_P (BB_END (a
))
657 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
660 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
664 block_label (basic_block block
)
666 if (block
== EXIT_BLOCK_PTR
)
669 if (!LABEL_P (BB_HEAD (block
)))
671 BB_HEAD (block
) = emit_label_before (gen_label_rtx (), BB_HEAD (block
));
674 return BB_HEAD (block
);
677 /* Attempt to perform edge redirection by replacing possibly complex jump
678 instruction by unconditional jump or removing jump completely. This can
679 apply only if all edges now point to the same block. The parameters and
680 return values are equivalent to redirect_edge_and_branch. */
683 try_redirect_by_replacing_jump (edge e
, basic_block target
, bool in_cfglayout
)
685 basic_block src
= e
->src
;
686 rtx insn
= BB_END (src
), kill_from
;
690 /* If we are partitioning hot/cold basic blocks, we don't want to
691 mess up unconditional or indirect jumps that cross between hot
694 Basic block partitioning may result in some jumps that appear to
695 be optimizable (or blocks that appear to be mergeable), but which really
696 must be left untouched (they are required to make it safely across
697 partition boundaries). See the comments at the top of
698 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
700 if (find_reg_note (insn
, REG_CROSSING_JUMP
, NULL_RTX
)
701 || BB_PARTITION (src
) != BB_PARTITION (target
))
704 /* We can replace or remove a complex jump only when we have exactly
705 two edges. Also, if we have exactly one outgoing edge, we can
707 if (EDGE_COUNT (src
->succs
) >= 3
708 /* Verify that all targets will be TARGET. Specifically, the
709 edge that is not E must also go to TARGET. */
710 || (EDGE_COUNT (src
->succs
) == 2
711 && EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
))
714 if (!onlyjump_p (insn
))
716 if ((!optimize
|| reload_completed
) && tablejump_p (insn
, NULL
, NULL
))
719 /* Avoid removing branch with side effects. */
720 set
= single_set (insn
);
721 if (!set
|| side_effects_p (set
))
724 /* In case we zap a conditional jump, we'll need to kill
725 the cc0 setter too. */
728 if (reg_mentioned_p (cc0_rtx
, PATTERN (insn
)))
729 kill_from
= PREV_INSN (insn
);
732 /* See if we can create the fallthru edge. */
733 if (in_cfglayout
|| can_fallthru (src
, target
))
736 fprintf (dump_file
, "Removing jump %i.\n", INSN_UID (insn
));
739 /* Selectively unlink whole insn chain. */
742 rtx insn
= src
->il
.rtl
->footer
;
744 delete_insn_chain (kill_from
, BB_END (src
));
746 /* Remove barriers but keep jumptables. */
749 if (BARRIER_P (insn
))
751 if (PREV_INSN (insn
))
752 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
754 src
->il
.rtl
->footer
= NEXT_INSN (insn
);
755 if (NEXT_INSN (insn
))
756 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
760 insn
= NEXT_INSN (insn
);
764 delete_insn_chain (kill_from
, PREV_INSN (BB_HEAD (target
)));
767 /* If this already is simplejump, redirect it. */
768 else if (simplejump_p (insn
))
770 if (e
->dest
== target
)
773 fprintf (dump_file
, "Redirecting jump %i from %i to %i.\n",
774 INSN_UID (insn
), e
->dest
->index
, target
->index
);
775 if (!redirect_jump (insn
, block_label (target
), 0))
777 gcc_assert (target
== EXIT_BLOCK_PTR
);
782 /* Cannot do anything for target exit block. */
783 else if (target
== EXIT_BLOCK_PTR
)
786 /* Or replace possibly complicated jump insn by simple jump insn. */
789 rtx target_label
= block_label (target
);
790 rtx barrier
, label
, table
;
792 emit_jump_insn_after_noloc (gen_jump (target_label
), insn
);
793 JUMP_LABEL (BB_END (src
)) = target_label
;
794 LABEL_NUSES (target_label
)++;
796 fprintf (dump_file
, "Replacing insn %i by jump %i\n",
797 INSN_UID (insn
), INSN_UID (BB_END (src
)));
800 delete_insn_chain (kill_from
, insn
);
802 /* Recognize a tablejump that we are converting to a
803 simple jump and remove its associated CODE_LABEL
804 and ADDR_VEC or ADDR_DIFF_VEC. */
805 if (tablejump_p (insn
, &label
, &table
))
806 delete_insn_chain (label
, table
);
808 barrier
= next_nonnote_insn (BB_END (src
));
809 if (!barrier
|| !BARRIER_P (barrier
))
810 emit_barrier_after (BB_END (src
));
813 if (barrier
!= NEXT_INSN (BB_END (src
)))
815 /* Move the jump before barrier so that the notes
816 which originally were or were created before jump table are
817 inside the basic block. */
818 rtx new_insn
= BB_END (src
);
821 for (tmp
= NEXT_INSN (BB_END (src
)); tmp
!= barrier
;
822 tmp
= NEXT_INSN (tmp
))
823 set_block_for_insn (tmp
, src
);
825 NEXT_INSN (PREV_INSN (new_insn
)) = NEXT_INSN (new_insn
);
826 PREV_INSN (NEXT_INSN (new_insn
)) = PREV_INSN (new_insn
);
828 NEXT_INSN (new_insn
) = barrier
;
829 NEXT_INSN (PREV_INSN (barrier
)) = new_insn
;
831 PREV_INSN (new_insn
) = PREV_INSN (barrier
);
832 PREV_INSN (barrier
) = new_insn
;
837 /* Keep only one edge out and set proper flags. */
838 if (!single_succ_p (src
))
840 gcc_assert (single_succ_p (src
));
842 e
= single_succ_edge (src
);
844 e
->flags
= EDGE_FALLTHRU
;
848 e
->probability
= REG_BR_PROB_BASE
;
849 e
->count
= src
->count
;
851 /* We don't want a block to end on a line-number note since that has
852 the potential of changing the code between -g and not -g. */
853 while (NOTE_P (BB_END (e
->src
))
854 && NOTE_LINE_NUMBER (BB_END (e
->src
)) >= 0)
855 delete_insn (BB_END (e
->src
));
857 if (e
->dest
!= target
)
858 redirect_edge_succ (e
, target
);
863 /* Return last loop_beg note appearing after INSN, before start of next
864 basic block. Return INSN if there are no such notes.
866 When emitting jump to redirect a fallthru edge, it should always appear
867 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
868 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
872 last_loop_beg_note (rtx insn
)
876 for (insn
= NEXT_INSN (insn
); insn
&& NOTE_P (insn
)
877 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
;
878 insn
= NEXT_INSN (insn
))
879 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
885 /* Redirect edge representing branch of (un)conditional jump or tablejump,
888 redirect_branch_edge (edge e
, basic_block target
)
891 rtx old_label
= BB_HEAD (e
->dest
);
892 basic_block src
= e
->src
;
893 rtx insn
= BB_END (src
);
895 /* We can only redirect non-fallthru edges of jump insn. */
896 if (e
->flags
& EDGE_FALLTHRU
)
898 else if (!JUMP_P (insn
))
901 /* Recognize a tablejump and adjust all matching cases. */
902 if (tablejump_p (insn
, NULL
, &tmp
))
906 rtx new_label
= block_label (target
);
908 if (target
== EXIT_BLOCK_PTR
)
910 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
911 vec
= XVEC (PATTERN (tmp
), 0);
913 vec
= XVEC (PATTERN (tmp
), 1);
915 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
916 if (XEXP (RTVEC_ELT (vec
, j
), 0) == old_label
)
918 RTVEC_ELT (vec
, j
) = gen_rtx_LABEL_REF (Pmode
, new_label
);
919 --LABEL_NUSES (old_label
);
920 ++LABEL_NUSES (new_label
);
923 /* Handle casesi dispatch insns. */
924 if ((tmp
= single_set (insn
)) != NULL
925 && SET_DEST (tmp
) == pc_rtx
926 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
927 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
928 && XEXP (XEXP (SET_SRC (tmp
), 2), 0) == old_label
)
930 XEXP (SET_SRC (tmp
), 2) = gen_rtx_LABEL_REF (Pmode
,
932 --LABEL_NUSES (old_label
);
933 ++LABEL_NUSES (new_label
);
938 /* ?? We may play the games with moving the named labels from
939 one basic block to the other in case only one computed_jump is
941 if (computed_jump_p (insn
)
942 /* A return instruction can't be redirected. */
943 || returnjump_p (insn
))
946 /* If the insn doesn't go where we think, we're confused. */
947 gcc_assert (JUMP_LABEL (insn
) == old_label
);
949 /* If the substitution doesn't succeed, die. This can happen
950 if the back end emitted unrecognizable instructions or if
951 target is exit block on some arches. */
952 if (!redirect_jump (insn
, block_label (target
), 0))
954 gcc_assert (target
== EXIT_BLOCK_PTR
);
960 fprintf (dump_file
, "Edge %i->%i redirected to %i\n",
961 e
->src
->index
, e
->dest
->index
, target
->index
);
963 if (e
->dest
!= target
)
964 e
= redirect_edge_succ_nodup (e
, target
);
968 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
969 expense of adding new instructions or reordering basic blocks.
971 Function can be also called with edge destination equivalent to the TARGET.
972 Then it should try the simplifications and do nothing if none is possible.
974 Return edge representing the branch if transformation succeeded. Return NULL
976 We still return NULL in case E already destinated TARGET and we didn't
977 managed to simplify instruction stream. */
980 rtl_redirect_edge_and_branch (edge e
, basic_block target
)
983 basic_block src
= e
->src
;
985 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
988 if (e
->dest
== target
)
991 if ((ret
= try_redirect_by_replacing_jump (e
, target
, false)) != NULL
)
993 src
->flags
|= BB_DIRTY
;
997 ret
= redirect_branch_edge (e
, target
);
1001 src
->flags
|= BB_DIRTY
;
1005 /* Like force_nonfallthru below, but additionally performs redirection
1006 Used by redirect_edge_and_branch_force. */
1009 force_nonfallthru_and_redirect (edge e
, basic_block target
)
1011 basic_block jump_block
, new_bb
= NULL
, src
= e
->src
;
1014 int abnormal_edge_flags
= 0;
1016 /* In the case the last instruction is conditional jump to the next
1017 instruction, first redirect the jump itself and then continue
1018 by creating a basic block afterwards to redirect fallthru edge. */
1019 if (e
->src
!= ENTRY_BLOCK_PTR
&& e
->dest
!= EXIT_BLOCK_PTR
1020 && any_condjump_p (BB_END (e
->src
))
1021 && JUMP_LABEL (BB_END (e
->src
)) == BB_HEAD (e
->dest
))
1024 edge b
= unchecked_make_edge (e
->src
, target
, 0);
1027 redirected
= redirect_jump (BB_END (e
->src
), block_label (target
), 0);
1028 gcc_assert (redirected
);
1030 note
= find_reg_note (BB_END (e
->src
), REG_BR_PROB
, NULL_RTX
);
1033 int prob
= INTVAL (XEXP (note
, 0));
1035 b
->probability
= prob
;
1036 b
->count
= e
->count
* prob
/ REG_BR_PROB_BASE
;
1037 e
->probability
-= e
->probability
;
1038 e
->count
-= b
->count
;
1039 if (e
->probability
< 0)
1046 if (e
->flags
& EDGE_ABNORMAL
)
1048 /* Irritating special case - fallthru edge to the same block as abnormal
1050 We can't redirect abnormal edge, but we still can split the fallthru
1051 one and create separate abnormal edge to original destination.
1052 This allows bb-reorder to make such edge non-fallthru. */
1053 gcc_assert (e
->dest
== target
);
1054 abnormal_edge_flags
= e
->flags
& ~(EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
);
1055 e
->flags
&= EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
;
1059 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1060 if (e
->src
== ENTRY_BLOCK_PTR
)
1062 /* We can't redirect the entry block. Create an empty block
1063 at the start of the function which we use to add the new
1069 basic_block bb
= create_basic_block (BB_HEAD (e
->dest
), NULL
, ENTRY_BLOCK_PTR
);
1071 /* Change the existing edge's source to be the new block, and add
1072 a new edge from the entry block to the new block. */
1074 for (ei
= ei_start (ENTRY_BLOCK_PTR
->succs
); (tmp
= ei_safe_edge (ei
)); )
1078 VEC_unordered_remove (edge
, ENTRY_BLOCK_PTR
->succs
, ei
.index
);
1088 VEC_safe_push (edge
, gc
, bb
->succs
, e
);
1089 make_single_succ_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_FALLTHRU
);
1093 if (EDGE_COUNT (e
->src
->succs
) >= 2 || abnormal_edge_flags
)
1095 /* Create the new structures. */
1097 /* If the old block ended with a tablejump, skip its table
1098 by searching forward from there. Otherwise start searching
1099 forward from the last instruction of the old block. */
1100 if (!tablejump_p (BB_END (e
->src
), NULL
, ¬e
))
1101 note
= BB_END (e
->src
);
1103 /* Position the new block correctly relative to loop notes. */
1104 note
= last_loop_beg_note (note
);
1105 note
= NEXT_INSN (note
);
1107 jump_block
= create_basic_block (note
, NULL
, e
->src
);
1108 jump_block
->count
= e
->count
;
1109 jump_block
->frequency
= EDGE_FREQUENCY (e
);
1110 jump_block
->loop_depth
= target
->loop_depth
;
1112 if (target
->il
.rtl
->global_live_at_start
)
1114 jump_block
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1115 jump_block
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1116 COPY_REG_SET (jump_block
->il
.rtl
->global_live_at_start
,
1117 target
->il
.rtl
->global_live_at_start
);
1118 COPY_REG_SET (jump_block
->il
.rtl
->global_live_at_end
,
1119 target
->il
.rtl
->global_live_at_start
);
1122 /* Make sure new block ends up in correct hot/cold section. */
1124 BB_COPY_PARTITION (jump_block
, e
->src
);
1125 if (flag_reorder_blocks_and_partition
1126 && targetm
.have_named_sections
1127 && JUMP_P (BB_END (jump_block
))
1128 && !any_condjump_p (BB_END (jump_block
))
1129 && (EDGE_SUCC (jump_block
, 0)->flags
& EDGE_CROSSING
))
1130 REG_NOTES (BB_END (jump_block
)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP
,
1137 new_edge
= make_edge (e
->src
, jump_block
, EDGE_FALLTHRU
);
1138 new_edge
->probability
= e
->probability
;
1139 new_edge
->count
= e
->count
;
1141 /* Redirect old edge. */
1142 redirect_edge_pred (e
, jump_block
);
1143 e
->probability
= REG_BR_PROB_BASE
;
1145 new_bb
= jump_block
;
1148 jump_block
= e
->src
;
1150 e
->flags
&= ~EDGE_FALLTHRU
;
1151 if (target
== EXIT_BLOCK_PTR
)
1154 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block
));
1161 rtx label
= block_label (target
);
1162 emit_jump_insn_after_noloc (gen_jump (label
), BB_END (jump_block
));
1163 JUMP_LABEL (BB_END (jump_block
)) = label
;
1164 LABEL_NUSES (label
)++;
1167 emit_barrier_after (BB_END (jump_block
));
1168 redirect_edge_succ_nodup (e
, target
);
1170 if (abnormal_edge_flags
)
1171 make_edge (src
, target
, abnormal_edge_flags
);
1176 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1177 (and possibly create new basic block) to make edge non-fallthru.
1178 Return newly created BB or NULL if none. */
1181 force_nonfallthru (edge e
)
1183 return force_nonfallthru_and_redirect (e
, e
->dest
);
1186 /* Redirect edge even at the expense of creating new jump insn or
1187 basic block. Return new basic block if created, NULL otherwise.
1188 Conversion must be possible. */
1191 rtl_redirect_edge_and_branch_force (edge e
, basic_block target
)
1193 if (redirect_edge_and_branch (e
, target
)
1194 || e
->dest
== target
)
1197 /* In case the edge redirection failed, try to force it to be non-fallthru
1198 and redirect newly created simplejump. */
1199 return force_nonfallthru_and_redirect (e
, target
);
1202 /* The given edge should potentially be a fallthru edge. If that is in
1203 fact true, delete the jump and barriers that are in the way. */
1206 rtl_tidy_fallthru_edge (edge e
)
1209 basic_block b
= e
->src
, c
= b
->next_bb
;
1211 /* ??? In a late-running flow pass, other folks may have deleted basic
1212 blocks by nopping out blocks, leaving multiple BARRIERs between here
1213 and the target label. They ought to be chastised and fixed.
1215 We can also wind up with a sequence of undeletable labels between
1216 one block and the next.
1218 So search through a sequence of barriers, labels, and notes for
1219 the head of block C and assert that we really do fall through. */
1221 for (q
= NEXT_INSN (BB_END (b
)); q
!= BB_HEAD (c
); q
= NEXT_INSN (q
))
1225 /* Remove what will soon cease being the jump insn from the source block.
1226 If block B consisted only of this single jump, turn it into a deleted
1231 && (any_uncondjump_p (q
)
1232 || single_succ_p (b
)))
1235 /* If this was a conditional jump, we need to also delete
1236 the insn that set cc0. */
1237 if (any_condjump_p (q
) && only_sets_cc0_p (PREV_INSN (q
)))
1243 /* We don't want a block to end on a line-number note since that has
1244 the potential of changing the code between -g and not -g. */
1245 while (NOTE_P (q
) && NOTE_LINE_NUMBER (q
) >= 0)
1249 /* Selectively unlink the sequence. */
1250 if (q
!= PREV_INSN (BB_HEAD (c
)))
1251 delete_insn_chain (NEXT_INSN (q
), PREV_INSN (BB_HEAD (c
)));
1253 e
->flags
|= EDGE_FALLTHRU
;
1256 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1257 is back edge of syntactic loop. */
1260 back_edge_of_syntactic_loop_p (basic_block bb1
, basic_block bb2
)
1269 /* ??? Could we guarantee that bb indices are monotone, so that we could
1270 just compare them? */
1271 for (bb
= bb1
; bb
&& bb
!= bb2
; bb
= bb
->next_bb
)
1277 for (insn
= BB_END (bb1
); insn
!= BB_HEAD (bb2
) && count
>= 0;
1278 insn
= NEXT_INSN (insn
))
1281 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1283 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1290 /* Should move basic block BB after basic block AFTER. NIY. */
1293 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED
,
1294 basic_block after ATTRIBUTE_UNUSED
)
1299 /* Split a (typically critical) edge. Return the new block.
1300 The edge must not be abnormal.
1302 ??? The code generally expects to be called on critical edges.
1303 The case of a block ending in an unconditional jump to a
1304 block with multiple predecessors is not handled optimally. */
1307 rtl_split_edge (edge edge_in
)
1312 /* Abnormal edges cannot be split. */
1313 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
1315 /* We are going to place the new block in front of edge destination.
1316 Avoid existence of fallthru predecessors. */
1317 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1322 FOR_EACH_EDGE (e
, ei
, edge_in
->dest
->preds
)
1323 if (e
->flags
& EDGE_FALLTHRU
)
1327 force_nonfallthru (e
);
1330 /* Create the basic block note.
1332 Where we place the note can have a noticeable impact on the generated
1333 code. Consider this cfg:
1343 If we need to insert an insn on the edge from block 0 to block 1,
1344 we want to ensure the instructions we insert are outside of any
1345 loop notes that physically sit between block 0 and block 1. Otherwise
1346 we confuse the loop optimizer into thinking the loop is a phony. */
1348 if (edge_in
->dest
!= EXIT_BLOCK_PTR
1349 && PREV_INSN (BB_HEAD (edge_in
->dest
))
1350 && NOTE_P (PREV_INSN (BB_HEAD (edge_in
->dest
)))
1351 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in
->dest
)))
1352 == NOTE_INSN_LOOP_BEG
)
1353 && !back_edge_of_syntactic_loop_p (edge_in
->dest
, edge_in
->src
))
1354 before
= PREV_INSN (BB_HEAD (edge_in
->dest
));
1355 else if (edge_in
->dest
!= EXIT_BLOCK_PTR
)
1356 before
= BB_HEAD (edge_in
->dest
);
1360 /* If this is a fall through edge to the exit block, the blocks might be
1361 not adjacent, and the right place is the after the source. */
1362 if (edge_in
->flags
& EDGE_FALLTHRU
&& edge_in
->dest
== EXIT_BLOCK_PTR
)
1364 before
= NEXT_INSN (BB_END (edge_in
->src
));
1367 && NOTE_LINE_NUMBER (before
) == NOTE_INSN_LOOP_END
)
1368 before
= NEXT_INSN (before
);
1369 bb
= create_basic_block (before
, NULL
, edge_in
->src
);
1370 BB_COPY_PARTITION (bb
, edge_in
->src
);
1374 bb
= create_basic_block (before
, NULL
, edge_in
->dest
->prev_bb
);
1375 /* ??? Why not edge_in->dest->prev_bb here? */
1376 BB_COPY_PARTITION (bb
, edge_in
->dest
);
1379 /* ??? This info is likely going to be out of date very soon. */
1380 if (edge_in
->dest
->il
.rtl
->global_live_at_start
)
1382 bb
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1383 bb
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1384 COPY_REG_SET (bb
->il
.rtl
->global_live_at_start
,
1385 edge_in
->dest
->il
.rtl
->global_live_at_start
);
1386 COPY_REG_SET (bb
->il
.rtl
->global_live_at_end
,
1387 edge_in
->dest
->il
.rtl
->global_live_at_start
);
1390 make_single_succ_edge (bb
, edge_in
->dest
, EDGE_FALLTHRU
);
1392 /* For non-fallthru edges, we must adjust the predecessor's
1393 jump instruction to target our new block. */
1394 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1396 edge redirected
= redirect_edge_and_branch (edge_in
, bb
);
1397 gcc_assert (redirected
);
1400 redirect_edge_succ (edge_in
, bb
);
1405 /* Queue instructions for insertion on an edge between two basic blocks.
1406 The new instructions and basic blocks (if any) will not appear in the
1407 CFG until commit_edge_insertions is called. */
1410 insert_insn_on_edge (rtx pattern
, edge e
)
1412 /* We cannot insert instructions on an abnormal critical edge.
1413 It will be easier to find the culprit if we die now. */
1414 gcc_assert (!((e
->flags
& EDGE_ABNORMAL
) && EDGE_CRITICAL_P (e
)));
1416 if (e
->insns
.r
== NULL_RTX
)
1419 push_to_sequence (e
->insns
.r
);
1421 emit_insn (pattern
);
1423 e
->insns
.r
= get_insns ();
1427 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1428 registers that are killed by the store. */
1430 mark_killed_regs (rtx reg
, rtx set ATTRIBUTE_UNUSED
, void *data
)
1432 regset killed
= data
;
1435 if (GET_CODE (reg
) == SUBREG
)
1436 reg
= SUBREG_REG (reg
);
1439 regno
= REGNO (reg
);
1440 if (regno
>= FIRST_PSEUDO_REGISTER
)
1441 SET_REGNO_REG_SET (killed
, regno
);
1444 for (i
= 0; i
< (int) hard_regno_nregs
[regno
][GET_MODE (reg
)]; i
++)
1445 SET_REGNO_REG_SET (killed
, regno
+ i
);
1449 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1450 it checks whether this will not clobber the registers that are live on the
1451 edge (i.e. it requires liveness information to be up-to-date) and if there
1452 are some, then it tries to save and restore them. Returns true if
1455 safe_insert_insn_on_edge (rtx insn
, edge e
)
1459 rtx save_regs
= NULL_RTX
;
1461 enum machine_mode mode
;
1462 reg_set_iterator rsi
;
1464 killed
= ALLOC_REG_SET (®_obstack
);
1466 for (x
= insn
; x
; x
= NEXT_INSN (x
))
1468 note_stores (PATTERN (x
), mark_killed_regs
, killed
);
1470 /* Mark all hard registers as killed. Register allocator/reload cannot
1471 cope with the situation when life range of hard register spans operation
1472 for that the appropriate register is needed, i.e. it would be unsafe to
1473 extend the life ranges of hard registers. */
1474 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
1475 if (!fixed_regs
[regno
]
1476 && !REGNO_PTR_FRAME_P (regno
))
1477 SET_REGNO_REG_SET (killed
, regno
);
1479 bitmap_and_into (killed
, e
->dest
->il
.rtl
->global_live_at_start
);
1481 EXECUTE_IF_SET_IN_REG_SET (killed
, 0, regno
, rsi
)
1483 mode
= regno
< FIRST_PSEUDO_REGISTER
1484 ? reg_raw_mode
[regno
]
1485 : GET_MODE (regno_reg_rtx
[regno
]);
1486 if (mode
== VOIDmode
)
1489 /* Avoid copying in CCmode if we can't. */
1490 if (!can_copy_p (mode
))
1493 save_regs
= alloc_EXPR_LIST (0,
1496 gen_raw_REG (mode
, regno
)),
1505 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1507 from
= XEXP (XEXP (x
, 0), 1);
1508 to
= XEXP (XEXP (x
, 0), 0);
1509 emit_move_insn (to
, from
);
1512 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1514 from
= XEXP (XEXP (x
, 0), 0);
1515 to
= XEXP (XEXP (x
, 0), 1);
1516 emit_move_insn (to
, from
);
1518 insn
= get_insns ();
1520 free_EXPR_LIST_list (&save_regs
);
1522 insert_insn_on_edge (insn
, e
);
1524 FREE_REG_SET (killed
);
1529 /* Update the CFG for the instructions queued on edge E. */
1532 commit_one_edge_insertion (edge e
, int watch_calls
)
1534 rtx before
= NULL_RTX
, after
= NULL_RTX
, insns
, tmp
, last
;
1535 basic_block bb
= NULL
;
1537 /* Pull the insns off the edge now since the edge might go away. */
1539 e
->insns
.r
= NULL_RTX
;
1541 /* Special case -- avoid inserting code between call and storing
1542 its return value. */
1543 if (watch_calls
&& (e
->flags
& EDGE_FALLTHRU
)
1544 && single_pred_p (e
->dest
)
1545 && e
->src
!= ENTRY_BLOCK_PTR
1546 && CALL_P (BB_END (e
->src
)))
1548 rtx next
= next_nonnote_insn (BB_END (e
->src
));
1550 after
= BB_HEAD (e
->dest
);
1551 /* The first insn after the call may be a stack pop, skip it. */
1553 && keep_with_call_p (next
))
1556 next
= next_nonnote_insn (next
);
1560 if (!before
&& !after
)
1562 /* Figure out where to put these things. If the destination has
1563 one predecessor, insert there. Except for the exit block. */
1564 if (single_pred_p (e
->dest
) && e
->dest
!= EXIT_BLOCK_PTR
)
1568 /* Get the location correct wrt a code label, and "nice" wrt
1569 a basic block note, and before everything else. */
1572 tmp
= NEXT_INSN (tmp
);
1573 if (NOTE_INSN_BASIC_BLOCK_P (tmp
))
1574 tmp
= NEXT_INSN (tmp
);
1575 if (tmp
== BB_HEAD (bb
))
1578 after
= PREV_INSN (tmp
);
1580 after
= get_last_insn ();
1583 /* If the source has one successor and the edge is not abnormal,
1584 insert there. Except for the entry block. */
1585 else if ((e
->flags
& EDGE_ABNORMAL
) == 0
1586 && single_succ_p (e
->src
)
1587 && e
->src
!= ENTRY_BLOCK_PTR
)
1591 /* It is possible to have a non-simple jump here. Consider a target
1592 where some forms of unconditional jumps clobber a register. This
1593 happens on the fr30 for example.
1595 We know this block has a single successor, so we can just emit
1596 the queued insns before the jump. */
1597 if (JUMP_P (BB_END (bb
)))
1598 for (before
= BB_END (bb
);
1599 NOTE_P (PREV_INSN (before
))
1600 && NOTE_LINE_NUMBER (PREV_INSN (before
)) ==
1601 NOTE_INSN_LOOP_BEG
; before
= PREV_INSN (before
))
1605 /* We'd better be fallthru, or we've lost track of
1607 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1609 after
= BB_END (bb
);
1612 /* Otherwise we must split the edge. */
1615 bb
= split_edge (e
);
1616 after
= BB_END (bb
);
1618 if (flag_reorder_blocks_and_partition
1619 && targetm
.have_named_sections
1620 && e
->src
!= ENTRY_BLOCK_PTR
1621 && BB_PARTITION (e
->src
) == BB_COLD_PARTITION
1622 && !(e
->flags
& EDGE_CROSSING
))
1624 rtx bb_note
, cur_insn
;
1627 for (cur_insn
= BB_HEAD (bb
); cur_insn
!= NEXT_INSN (BB_END (bb
));
1628 cur_insn
= NEXT_INSN (cur_insn
))
1629 if (NOTE_P (cur_insn
)
1630 && NOTE_LINE_NUMBER (cur_insn
) == NOTE_INSN_BASIC_BLOCK
)
1636 if (JUMP_P (BB_END (bb
))
1637 && !any_condjump_p (BB_END (bb
))
1638 && (single_succ_edge (bb
)->flags
& EDGE_CROSSING
))
1639 REG_NOTES (BB_END (bb
)) = gen_rtx_EXPR_LIST
1640 (REG_CROSSING_JUMP
, NULL_RTX
, REG_NOTES (BB_END (bb
)));
1645 /* Now that we've found the spot, do the insertion. */
1649 emit_insn_before_noloc (insns
, before
);
1650 last
= prev_nonnote_insn (before
);
1653 last
= emit_insn_after_noloc (insns
, after
);
1655 if (returnjump_p (last
))
1657 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1658 This is not currently a problem because this only happens
1659 for the (single) epilogue, which already has a fallthru edge
1662 e
= single_succ_edge (bb
);
1663 gcc_assert (e
->dest
== EXIT_BLOCK_PTR
1664 && single_succ_p (bb
) && (e
->flags
& EDGE_FALLTHRU
));
1666 e
->flags
&= ~EDGE_FALLTHRU
;
1667 emit_barrier_after (last
);
1670 delete_insn (before
);
1673 gcc_assert (!JUMP_P (last
));
1675 /* Mark the basic block for find_many_sub_basic_blocks. */
1679 /* Update the CFG for all queued instructions. */
1682 commit_edge_insertions (void)
1686 bool changed
= false;
1688 #ifdef ENABLE_CHECKING
1689 verify_flow_info ();
1692 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1697 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1701 commit_one_edge_insertion (e
, false);
1708 blocks
= sbitmap_alloc (last_basic_block
);
1709 sbitmap_zero (blocks
);
1713 SET_BIT (blocks
, bb
->index
);
1714 /* Check for forgotten bb->aux values before commit_edge_insertions
1716 gcc_assert (bb
->aux
== &bb
->aux
);
1719 find_many_sub_basic_blocks (blocks
);
1720 sbitmap_free (blocks
);
1723 /* Update the CFG for all queued instructions, taking special care of inserting
1724 code on edges between call and storing its return value. */
1727 commit_edge_insertions_watch_calls (void)
1731 bool changed
= false;
1733 #ifdef ENABLE_CHECKING
1734 verify_flow_info ();
1737 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1742 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1746 commit_one_edge_insertion (e
, true);
1753 blocks
= sbitmap_alloc (last_basic_block
);
1754 sbitmap_zero (blocks
);
1758 SET_BIT (blocks
, bb
->index
);
1759 /* Check for forgotten bb->aux values before commit_edge_insertions
1761 gcc_assert (bb
->aux
== &bb
->aux
);
1764 find_many_sub_basic_blocks (blocks
);
1765 sbitmap_free (blocks
);
1768 /* Print out RTL-specific basic block information (live information
1769 at start and end). */
1772 rtl_dump_bb (basic_block bb
, FILE *outf
, int indent
)
1778 s_indent
= alloca ((size_t) indent
+ 1);
1779 memset (s_indent
, ' ', (size_t) indent
);
1780 s_indent
[indent
] = '\0';
1782 fprintf (outf
, ";;%s Registers live at start: ", s_indent
);
1783 dump_regset (bb
->il
.rtl
->global_live_at_start
, outf
);
1786 for (insn
= BB_HEAD (bb
), last
= NEXT_INSN (BB_END (bb
)); insn
!= last
;
1787 insn
= NEXT_INSN (insn
))
1788 print_rtl_single (outf
, insn
);
1790 fprintf (outf
, ";;%s Registers live at end: ", s_indent
);
1791 dump_regset (bb
->il
.rtl
->global_live_at_end
, outf
);
1795 /* Like print_rtl, but also print out live information for the start of each
1799 print_rtl_with_bb (FILE *outf
, rtx rtx_first
)
1804 fprintf (outf
, "(nil)\n");
1807 enum bb_state
{ NOT_IN_BB
, IN_ONE_BB
, IN_MULTIPLE_BB
};
1808 int max_uid
= get_max_uid ();
1809 basic_block
*start
= xcalloc (max_uid
, sizeof (basic_block
));
1810 basic_block
*end
= xcalloc (max_uid
, sizeof (basic_block
));
1811 enum bb_state
*in_bb_p
= xcalloc (max_uid
, sizeof (enum bb_state
));
1815 FOR_EACH_BB_REVERSE (bb
)
1819 start
[INSN_UID (BB_HEAD (bb
))] = bb
;
1820 end
[INSN_UID (BB_END (bb
))] = bb
;
1821 for (x
= BB_HEAD (bb
); x
!= NULL_RTX
; x
= NEXT_INSN (x
))
1823 enum bb_state state
= IN_MULTIPLE_BB
;
1825 if (in_bb_p
[INSN_UID (x
)] == NOT_IN_BB
)
1827 in_bb_p
[INSN_UID (x
)] = state
;
1829 if (x
== BB_END (bb
))
1834 for (tmp_rtx
= rtx_first
; NULL
!= tmp_rtx
; tmp_rtx
= NEXT_INSN (tmp_rtx
))
1838 if ((bb
= start
[INSN_UID (tmp_rtx
)]) != NULL
)
1840 fprintf (outf
, ";; Start of basic block %d, registers live:",
1842 dump_regset (bb
->il
.rtl
->global_live_at_start
, outf
);
1846 if (in_bb_p
[INSN_UID (tmp_rtx
)] == NOT_IN_BB
1847 && !NOTE_P (tmp_rtx
)
1848 && !BARRIER_P (tmp_rtx
))
1849 fprintf (outf
, ";; Insn is not within a basic block\n");
1850 else if (in_bb_p
[INSN_UID (tmp_rtx
)] == IN_MULTIPLE_BB
)
1851 fprintf (outf
, ";; Insn is in multiple basic blocks\n");
1853 did_output
= print_rtl_single (outf
, tmp_rtx
);
1855 if ((bb
= end
[INSN_UID (tmp_rtx
)]) != NULL
)
1857 fprintf (outf
, ";; End of basic block %d, registers live:\n",
1859 dump_regset (bb
->il
.rtl
->global_live_at_end
, outf
);
1872 if (current_function_epilogue_delay_list
!= 0)
1874 fprintf (outf
, "\n;; Insns in epilogue delay list:\n\n");
1875 for (tmp_rtx
= current_function_epilogue_delay_list
; tmp_rtx
!= 0;
1876 tmp_rtx
= XEXP (tmp_rtx
, 1))
1877 print_rtl_single (outf
, XEXP (tmp_rtx
, 0));
1882 update_br_prob_note (basic_block bb
)
1885 if (!JUMP_P (BB_END (bb
)))
1887 note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
);
1888 if (!note
|| INTVAL (XEXP (note
, 0)) == BRANCH_EDGE (bb
)->probability
)
1890 XEXP (note
, 0) = GEN_INT (BRANCH_EDGE (bb
)->probability
);
1893 /* Verify the CFG and RTL consistency common for both underlying RTL and
1896 Currently it does following checks:
1898 - test head/end pointers
1899 - overlapping of basic blocks
1900 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1901 - tails of basic blocks (ensure that boundary is necessary)
1902 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1903 and NOTE_INSN_BASIC_BLOCK
1904 - verify that no fall_thru edge crosses hot/cold partition boundaries
1906 In future it can be extended check a lot of other stuff as well
1907 (reachability of basic blocks, life information, etc. etc.). */
1910 rtl_verify_flow_info_1 (void)
1912 const int max_uid
= get_max_uid ();
1913 rtx last_head
= get_last_insn ();
1914 basic_block
*bb_info
;
1919 bb_info
= xcalloc (max_uid
, sizeof (basic_block
));
1921 FOR_EACH_BB_REVERSE (bb
)
1923 rtx head
= BB_HEAD (bb
);
1924 rtx end
= BB_END (bb
);
1926 /* Verify the end of the basic block is in the INSN chain. */
1927 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1931 if (!(bb
->flags
& BB_RTL
))
1933 error ("BB_RTL flag not set for block %d", bb
->index
);
1939 error ("end insn %d for block %d not found in the insn stream",
1940 INSN_UID (end
), bb
->index
);
1944 /* Work backwards from the end to the head of the basic block
1945 to verify the head is in the RTL chain. */
1946 for (; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1948 /* While walking over the insn chain, verify insns appear
1949 in only one basic block and initialize the BB_INFO array
1950 used by other passes. */
1951 if (bb_info
[INSN_UID (x
)] != NULL
)
1953 error ("insn %d is in multiple basic blocks (%d and %d)",
1954 INSN_UID (x
), bb
->index
, bb_info
[INSN_UID (x
)]->index
);
1958 bb_info
[INSN_UID (x
)] = bb
;
1965 error ("head insn %d for block %d not found in the insn stream",
1966 INSN_UID (head
), bb
->index
);
1973 /* Now check the basic blocks (boundaries etc.) */
1974 FOR_EACH_BB_REVERSE (bb
)
1976 int n_fallthru
= 0, n_eh
= 0, n_call
= 0, n_abnormal
= 0, n_branch
= 0;
1977 edge e
, fallthru
= NULL
;
1981 if (JUMP_P (BB_END (bb
))
1982 && (note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
))
1983 && EDGE_COUNT (bb
->succs
) >= 2
1984 && any_condjump_p (BB_END (bb
)))
1986 if (INTVAL (XEXP (note
, 0)) != BRANCH_EDGE (bb
)->probability
1987 && profile_status
!= PROFILE_ABSENT
)
1989 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1990 INTVAL (XEXP (note
, 0)), BRANCH_EDGE (bb
)->probability
);
1994 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1996 if (e
->flags
& EDGE_FALLTHRU
)
1998 n_fallthru
++, fallthru
= e
;
1999 if ((e
->flags
& EDGE_CROSSING
)
2000 || (BB_PARTITION (e
->src
) != BB_PARTITION (e
->dest
)
2001 && e
->src
!= ENTRY_BLOCK_PTR
2002 && e
->dest
!= EXIT_BLOCK_PTR
))
2004 error ("fallthru edge crosses section boundary (bb %i)",
2010 if ((e
->flags
& ~(EDGE_DFS_BACK
2012 | EDGE_IRREDUCIBLE_LOOP
2014 | EDGE_CROSSING
)) == 0)
2017 if (e
->flags
& EDGE_ABNORMAL_CALL
)
2020 if (e
->flags
& EDGE_EH
)
2022 else if (e
->flags
& EDGE_ABNORMAL
)
2026 if (n_eh
&& GET_CODE (PATTERN (BB_END (bb
))) != RESX
2027 && !find_reg_note (BB_END (bb
), REG_EH_REGION
, NULL_RTX
))
2029 error ("missing REG_EH_REGION note in the end of bb %i", bb
->index
);
2033 && (!JUMP_P (BB_END (bb
))
2034 || (n_branch
> 1 && (any_uncondjump_p (BB_END (bb
))
2035 || any_condjump_p (BB_END (bb
))))))
2037 error ("too many outgoing branch edges from bb %i", bb
->index
);
2040 if (n_fallthru
&& any_uncondjump_p (BB_END (bb
)))
2042 error ("fallthru edge after unconditional jump %i", bb
->index
);
2045 if (n_branch
!= 1 && any_uncondjump_p (BB_END (bb
)))
2047 error ("wrong amount of branch edges after unconditional jump %i", bb
->index
);
2050 if (n_branch
!= 1 && any_condjump_p (BB_END (bb
))
2051 && JUMP_LABEL (BB_END (bb
)) != BB_HEAD (fallthru
->dest
))
2053 error ("wrong amount of branch edges after conditional jump %i",
2057 if (n_call
&& !CALL_P (BB_END (bb
)))
2059 error ("call edges for non-call insn in bb %i", bb
->index
);
2063 && (!CALL_P (BB_END (bb
)) && n_call
!= n_abnormal
)
2064 && (!JUMP_P (BB_END (bb
))
2065 || any_condjump_p (BB_END (bb
))
2066 || any_uncondjump_p (BB_END (bb
))))
2068 error ("abnormal edges for no purpose in bb %i", bb
->index
);
2072 for (x
= BB_HEAD (bb
); x
!= NEXT_INSN (BB_END (bb
)); x
= NEXT_INSN (x
))
2073 /* We may have a barrier inside a basic block before dead code
2074 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2075 if (!BARRIER_P (x
) && BLOCK_FOR_INSN (x
) != bb
)
2078 if (! BLOCK_FOR_INSN (x
))
2080 ("insn %d inside basic block %d but block_for_insn is NULL",
2081 INSN_UID (x
), bb
->index
);
2084 ("insn %d inside basic block %d but block_for_insn is %i",
2085 INSN_UID (x
), bb
->index
, BLOCK_FOR_INSN (x
)->index
);
2090 /* OK pointers are correct. Now check the header of basic
2091 block. It ought to contain optional CODE_LABEL followed
2092 by NOTE_BASIC_BLOCK. */
2096 if (BB_END (bb
) == x
)
2098 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2106 if (!NOTE_INSN_BASIC_BLOCK_P (x
) || NOTE_BASIC_BLOCK (x
) != bb
)
2108 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2113 if (BB_END (bb
) == x
)
2114 /* Do checks for empty blocks here. */
2117 for (x
= NEXT_INSN (x
); x
; x
= NEXT_INSN (x
))
2119 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2121 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2122 INSN_UID (x
), bb
->index
);
2126 if (x
== BB_END (bb
))
2129 if (control_flow_insn_p (x
))
2131 error ("in basic block %d:", bb
->index
);
2132 fatal_insn ("flow control insn inside a basic block", x
);
2142 /* Verify the CFG and RTL consistency common for both underlying RTL and
2145 Currently it does following checks:
2146 - all checks of rtl_verify_flow_info_1
2147 - check that all insns are in the basic blocks
2148 (except the switch handling code, barriers and notes)
2149 - check that all returns are followed by barriers
2150 - check that all fallthru edge points to the adjacent blocks. */
2152 rtl_verify_flow_info (void)
2155 int err
= rtl_verify_flow_info_1 ();
2158 const rtx rtx_first
= get_insns ();
2159 basic_block last_bb_seen
= ENTRY_BLOCK_PTR
, curr_bb
= NULL
;
2161 FOR_EACH_BB_REVERSE (bb
)
2166 if (bb
->predictions
)
2168 error ("bb prediction set for block %i, but it is not used in RTL land", bb
->index
);
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
- NUM_FIXED_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 /* There are three types of edges we need to handle correctly here: EH
2301 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2302 latter can appear when nonlocal gotos are used. */
2303 if (e
->flags
& EDGE_EH
)
2305 if (can_throw_internal (BB_END (bb
))
2306 /* If this is a call edge, verify that this is a call insn. */
2307 && (! (e
->flags
& EDGE_ABNORMAL_CALL
)
2308 || CALL_P (BB_END (bb
))))
2314 else if (e
->flags
& EDGE_ABNORMAL_CALL
)
2316 if (CALL_P (BB_END (bb
))
2317 && (! (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
))
2318 || INTVAL (XEXP (note
, 0)) >= 0))
2331 bb
->flags
|= BB_DIRTY
;
2341 /* We do care only about conditional jumps and simplejumps. */
2342 if (!any_condjump_p (insn
)
2343 && !returnjump_p (insn
)
2344 && !simplejump_p (insn
))
2347 /* Branch probability/prediction notes are defined only for
2348 condjumps. We've possibly turned condjump into simplejump. */
2349 if (simplejump_p (insn
))
2351 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2353 remove_note (insn
, note
);
2354 while ((note
= find_reg_note (insn
, REG_BR_PRED
, NULL
)))
2355 remove_note (insn
, note
);
2358 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2360 /* Avoid abnormal flags to leak from computed jumps turned
2361 into simplejumps. */
2363 e
->flags
&= ~EDGE_ABNORMAL
;
2365 /* See if this edge is one we should keep. */
2366 if ((e
->flags
& EDGE_FALLTHRU
) && any_condjump_p (insn
))
2367 /* A conditional jump can fall through into the next
2368 block, so we should keep the edge. */
2373 else if (e
->dest
!= EXIT_BLOCK_PTR
2374 && BB_HEAD (e
->dest
) == JUMP_LABEL (insn
))
2375 /* If the destination block is the target of the jump,
2381 else if (e
->dest
== EXIT_BLOCK_PTR
&& returnjump_p (insn
))
2382 /* If the destination block is the exit block, and this
2383 instruction is a return, then keep the edge. */
2388 else if ((e
->flags
& EDGE_EH
) && can_throw_internal (insn
))
2389 /* Keep the edges that correspond to exceptions thrown by
2390 this instruction and rematerialize the EDGE_ABNORMAL
2391 flag we just cleared above. */
2393 e
->flags
|= EDGE_ABNORMAL
;
2398 /* We do not need this edge. */
2399 bb
->flags
|= BB_DIRTY
;
2404 if (EDGE_COUNT (bb
->succs
) == 0 || !purged
)
2408 fprintf (dump_file
, "Purged edges from bb %i\n", bb
->index
);
2413 /* Redistribute probabilities. */
2414 if (single_succ_p (bb
))
2416 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2417 single_succ_edge (bb
)->count
= bb
->count
;
2421 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2425 b
= BRANCH_EDGE (bb
);
2426 f
= FALLTHRU_EDGE (bb
);
2427 b
->probability
= INTVAL (XEXP (note
, 0));
2428 f
->probability
= REG_BR_PROB_BASE
- b
->probability
;
2429 b
->count
= bb
->count
* b
->probability
/ REG_BR_PROB_BASE
;
2430 f
->count
= bb
->count
* f
->probability
/ REG_BR_PROB_BASE
;
2435 else if (CALL_P (insn
) && SIBLING_CALL_P (insn
))
2437 /* First, there should not be any EH or ABCALL edges resulting
2438 from non-local gotos and the like. If there were, we shouldn't
2439 have created the sibcall in the first place. Second, there
2440 should of course never have been a fallthru edge. */
2441 gcc_assert (single_succ_p (bb
));
2442 gcc_assert (single_succ_edge (bb
)->flags
2443 == (EDGE_SIBCALL
| EDGE_ABNORMAL
));
2448 /* If we don't see a jump insn, we don't know exactly why the block would
2449 have been broken at this point. Look for a simple, non-fallthru edge,
2450 as these are only created by conditional branches. If we find such an
2451 edge we know that there used to be a jump here and can then safely
2452 remove all non-fallthru edges. */
2454 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2455 if (! (e
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
)))
2464 /* Remove all but the fake and fallthru edges. The fake edge may be
2465 the only successor for this block in the case of noreturn
2467 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2469 if (!(e
->flags
& (EDGE_FALLTHRU
| EDGE_FAKE
)))
2471 bb
->flags
|= BB_DIRTY
;
2479 gcc_assert (single_succ_p (bb
));
2481 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2482 single_succ_edge (bb
)->count
= bb
->count
;
2485 fprintf (dump_file
, "Purged non-fallthru edges from bb %i\n",
2490 /* Search all basic blocks for potentially dead edges and purge them. Return
2491 true if some edge has been eliminated. */
2494 purge_all_dead_edges (void)
2501 bool purged_here
= purge_dead_edges (bb
);
2503 purged
|= purged_here
;
2509 /* Same as split_block but update cfg_layout structures. */
2512 cfg_layout_split_block (basic_block bb
, void *insnp
)
2515 basic_block new_bb
= rtl_split_block (bb
, insn
);
2517 new_bb
->il
.rtl
->footer
= bb
->il
.rtl
->footer
;
2518 bb
->il
.rtl
->footer
= NULL
;
2524 /* Redirect Edge to DEST. */
2526 cfg_layout_redirect_edge_and_branch (edge e
, basic_block dest
)
2528 basic_block src
= e
->src
;
2531 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
2534 if (e
->dest
== dest
)
2537 if (e
->src
!= ENTRY_BLOCK_PTR
2538 && (ret
= try_redirect_by_replacing_jump (e
, dest
, true)))
2540 src
->flags
|= BB_DIRTY
;
2544 if (e
->src
== ENTRY_BLOCK_PTR
2545 && (e
->flags
& EDGE_FALLTHRU
) && !(e
->flags
& EDGE_COMPLEX
))
2548 fprintf (dump_file
, "Redirecting entry edge from bb %i to %i\n",
2549 e
->src
->index
, dest
->index
);
2551 e
->src
->flags
|= BB_DIRTY
;
2552 redirect_edge_succ (e
, dest
);
2556 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2557 in the case the basic block appears to be in sequence. Avoid this
2560 if (e
->flags
& EDGE_FALLTHRU
)
2562 /* Redirect any branch edges unified with the fallthru one. */
2563 if (JUMP_P (BB_END (src
))
2564 && label_is_jump_target_p (BB_HEAD (e
->dest
),
2570 fprintf (dump_file
, "Fallthru edge unified with branch "
2571 "%i->%i redirected to %i\n",
2572 e
->src
->index
, e
->dest
->index
, dest
->index
);
2573 e
->flags
&= ~EDGE_FALLTHRU
;
2574 redirected
= redirect_branch_edge (e
, dest
);
2575 gcc_assert (redirected
);
2576 e
->flags
|= EDGE_FALLTHRU
;
2577 e
->src
->flags
|= BB_DIRTY
;
2580 /* In case we are redirecting fallthru edge to the branch edge
2581 of conditional jump, remove it. */
2582 if (EDGE_COUNT (src
->succs
) == 2)
2584 /* Find the edge that is different from E. */
2585 edge s
= EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
);
2588 && any_condjump_p (BB_END (src
))
2589 && onlyjump_p (BB_END (src
)))
2590 delete_insn (BB_END (src
));
2592 ret
= redirect_edge_succ_nodup (e
, dest
);
2594 fprintf (dump_file
, "Fallthru edge %i->%i redirected to %i\n",
2595 e
->src
->index
, e
->dest
->index
, dest
->index
);
2598 ret
= redirect_branch_edge (e
, dest
);
2600 /* We don't want simplejumps in the insn stream during cfglayout. */
2601 gcc_assert (!simplejump_p (BB_END (src
)));
2603 src
->flags
|= BB_DIRTY
;
2607 /* Simple wrapper as we always can redirect fallthru edges. */
2609 cfg_layout_redirect_edge_and_branch_force (edge e
, basic_block dest
)
2611 edge redirected
= cfg_layout_redirect_edge_and_branch (e
, dest
);
2613 gcc_assert (redirected
);
2617 /* Same as delete_basic_block but update cfg_layout structures. */
2620 cfg_layout_delete_block (basic_block bb
)
2622 rtx insn
, next
, prev
= PREV_INSN (BB_HEAD (bb
)), *to
, remaints
;
2624 if (bb
->il
.rtl
->header
)
2626 next
= BB_HEAD (bb
);
2628 NEXT_INSN (prev
) = bb
->il
.rtl
->header
;
2630 set_first_insn (bb
->il
.rtl
->header
);
2631 PREV_INSN (bb
->il
.rtl
->header
) = prev
;
2632 insn
= bb
->il
.rtl
->header
;
2633 while (NEXT_INSN (insn
))
2634 insn
= NEXT_INSN (insn
);
2635 NEXT_INSN (insn
) = next
;
2636 PREV_INSN (next
) = insn
;
2638 next
= NEXT_INSN (BB_END (bb
));
2639 if (bb
->il
.rtl
->footer
)
2641 insn
= bb
->il
.rtl
->footer
;
2644 if (BARRIER_P (insn
))
2646 if (PREV_INSN (insn
))
2647 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
2649 bb
->il
.rtl
->footer
= NEXT_INSN (insn
);
2650 if (NEXT_INSN (insn
))
2651 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
2655 insn
= NEXT_INSN (insn
);
2657 if (bb
->il
.rtl
->footer
)
2660 NEXT_INSN (insn
) = bb
->il
.rtl
->footer
;
2661 PREV_INSN (bb
->il
.rtl
->footer
) = insn
;
2662 while (NEXT_INSN (insn
))
2663 insn
= NEXT_INSN (insn
);
2664 NEXT_INSN (insn
) = next
;
2666 PREV_INSN (next
) = insn
;
2668 set_last_insn (insn
);
2671 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2672 to
= &bb
->next_bb
->il
.rtl
->header
;
2674 to
= &cfg_layout_function_footer
;
2676 rtl_delete_block (bb
);
2679 prev
= NEXT_INSN (prev
);
2681 prev
= get_insns ();
2683 next
= PREV_INSN (next
);
2685 next
= get_last_insn ();
2687 if (next
&& NEXT_INSN (next
) != prev
)
2689 remaints
= unlink_insn_chain (prev
, next
);
2691 while (NEXT_INSN (insn
))
2692 insn
= NEXT_INSN (insn
);
2693 NEXT_INSN (insn
) = *to
;
2695 PREV_INSN (*to
) = insn
;
2700 /* Return true when blocks A and B can be safely merged. */
2702 cfg_layout_can_merge_blocks_p (basic_block a
, basic_block b
)
2704 /* If we are partitioning hot/cold basic blocks, we don't want to
2705 mess up unconditional or indirect jumps that cross between hot
2708 Basic block partitioning may result in some jumps that appear to
2709 be optimizable (or blocks that appear to be mergeable), but which really
2710 must be left untouched (they are required to make it safely across
2711 partition boundaries). See the comments at the top of
2712 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2714 if (BB_PARTITION (a
) != BB_PARTITION (b
))
2717 /* There must be exactly one edge in between the blocks. */
2718 return (single_succ_p (a
)
2719 && single_succ (a
) == b
2720 && single_pred_p (b
) == 1
2722 /* Must be simple edge. */
2723 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
2724 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
2725 /* If the jump insn has side effects,
2726 we can't kill the edge. */
2727 && (!JUMP_P (BB_END (a
))
2728 || (reload_completed
2729 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
2732 /* Merge block A and B. The blocks must be mergeable. */
2735 cfg_layout_merge_blocks (basic_block a
, basic_block b
)
2737 #ifdef ENABLE_CHECKING
2738 gcc_assert (cfg_layout_can_merge_blocks_p (a
, b
));
2741 /* If there was a CODE_LABEL beginning B, delete it. */
2742 if (LABEL_P (BB_HEAD (b
)))
2744 /* This might have been an EH label that no longer has incoming
2745 EH edges. Update data structures to match. */
2746 maybe_remove_eh_handler (BB_HEAD (b
));
2748 delete_insn (BB_HEAD (b
));
2751 /* We should have fallthru edge in a, or we can do dummy redirection to get
2753 if (JUMP_P (BB_END (a
)))
2754 try_redirect_by_replacing_jump (EDGE_SUCC (a
, 0), b
, true);
2755 gcc_assert (!JUMP_P (BB_END (a
)));
2757 /* Possible line number notes should appear in between. */
2758 if (b
->il
.rtl
->header
)
2760 rtx first
= BB_END (a
), last
;
2762 last
= emit_insn_after_noloc (b
->il
.rtl
->header
, BB_END (a
));
2763 delete_insn_chain (NEXT_INSN (first
), last
);
2764 b
->il
.rtl
->header
= NULL
;
2767 /* In the case basic blocks are not adjacent, move them around. */
2768 if (NEXT_INSN (BB_END (a
)) != BB_HEAD (b
))
2770 rtx first
= unlink_insn_chain (BB_HEAD (b
), BB_END (b
));
2772 emit_insn_after_noloc (first
, BB_END (a
));
2773 /* Skip possible DELETED_LABEL insn. */
2774 if (!NOTE_INSN_BASIC_BLOCK_P (first
))
2775 first
= NEXT_INSN (first
);
2776 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first
));
2778 delete_insn (first
);
2780 /* Otherwise just re-associate the instructions. */
2785 for (insn
= BB_HEAD (b
);
2786 insn
!= NEXT_INSN (BB_END (b
));
2787 insn
= NEXT_INSN (insn
))
2788 set_block_for_insn (insn
, a
);
2790 /* Skip possible DELETED_LABEL insn. */
2791 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
2792 insn
= NEXT_INSN (insn
);
2793 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
2795 BB_END (a
) = BB_END (b
);
2799 /* Possible tablejumps and barriers should appear after the block. */
2800 if (b
->il
.rtl
->footer
)
2802 if (!a
->il
.rtl
->footer
)
2803 a
->il
.rtl
->footer
= b
->il
.rtl
->footer
;
2806 rtx last
= a
->il
.rtl
->footer
;
2808 while (NEXT_INSN (last
))
2809 last
= NEXT_INSN (last
);
2810 NEXT_INSN (last
) = b
->il
.rtl
->footer
;
2811 PREV_INSN (b
->il
.rtl
->footer
) = last
;
2813 b
->il
.rtl
->footer
= NULL
;
2815 a
->il
.rtl
->global_live_at_end
= b
->il
.rtl
->global_live_at_end
;
2818 fprintf (dump_file
, "Merged blocks %d and %d.\n",
2819 a
->index
, b
->index
);
2825 cfg_layout_split_edge (edge e
)
2827 basic_block new_bb
=
2828 create_basic_block (e
->src
!= ENTRY_BLOCK_PTR
2829 ? NEXT_INSN (BB_END (e
->src
)) : get_insns (),
2832 /* ??? This info is likely going to be out of date very soon, but we must
2833 create it to avoid getting an ICE later. */
2834 if (e
->dest
->il
.rtl
->global_live_at_start
)
2836 new_bb
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
2837 new_bb
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
2838 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_start
,
2839 e
->dest
->il
.rtl
->global_live_at_start
);
2840 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_end
,
2841 e
->dest
->il
.rtl
->global_live_at_start
);
2844 make_edge (new_bb
, e
->dest
, EDGE_FALLTHRU
);
2845 redirect_edge_and_branch_force (e
, new_bb
);
2850 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2853 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED
)
2857 /* Return 1 if BB ends with a call, possibly followed by some
2858 instructions that must stay with the call, 0 otherwise. */
2861 rtl_block_ends_with_call_p (basic_block bb
)
2863 rtx insn
= BB_END (bb
);
2865 while (!CALL_P (insn
)
2866 && insn
!= BB_HEAD (bb
)
2867 && keep_with_call_p (insn
))
2868 insn
= PREV_INSN (insn
);
2869 return (CALL_P (insn
));
2872 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2875 rtl_block_ends_with_condjump_p (basic_block bb
)
2877 return any_condjump_p (BB_END (bb
));
2880 /* Return true if we need to add fake edge to exit.
2881 Helper function for rtl_flow_call_edges_add. */
2884 need_fake_edge_p (rtx insn
)
2890 && !SIBLING_CALL_P (insn
)
2891 && !find_reg_note (insn
, REG_NORETURN
, NULL
)
2892 && !CONST_OR_PURE_CALL_P (insn
)))
2895 return ((GET_CODE (PATTERN (insn
)) == ASM_OPERANDS
2896 && MEM_VOLATILE_P (PATTERN (insn
)))
2897 || (GET_CODE (PATTERN (insn
)) == PARALLEL
2898 && asm_noperands (insn
) != -1
2899 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn
), 0, 0)))
2900 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
);
2903 /* Add fake edges to the function exit for any non constant and non noreturn
2904 calls, volatile inline assembly in the bitmap of blocks specified by
2905 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2908 The goal is to expose cases in which entering a basic block does not imply
2909 that all subsequent instructions must be executed. */
2912 rtl_flow_call_edges_add (sbitmap blocks
)
2915 int blocks_split
= 0;
2916 int last_bb
= last_basic_block
;
2917 bool check_last_block
= false;
2919 if (n_basic_blocks
== NUM_FIXED_BLOCKS
)
2923 check_last_block
= true;
2925 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
2927 /* In the last basic block, before epilogue generation, there will be
2928 a fallthru edge to EXIT. Special care is required if the last insn
2929 of the last basic block is a call because make_edge folds duplicate
2930 edges, which would result in the fallthru edge also being marked
2931 fake, which would result in the fallthru edge being removed by
2932 remove_fake_edges, which would result in an invalid CFG.
2934 Moreover, we can't elide the outgoing fake edge, since the block
2935 profiler needs to take this into account in order to solve the minimal
2936 spanning tree in the case that the call doesn't return.
2938 Handle this by adding a dummy instruction in a new last basic block. */
2939 if (check_last_block
)
2941 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
2942 rtx insn
= BB_END (bb
);
2944 /* Back up past insns that must be kept in the same block as a call. */
2945 while (insn
!= BB_HEAD (bb
)
2946 && keep_with_call_p (insn
))
2947 insn
= PREV_INSN (insn
);
2949 if (need_fake_edge_p (insn
))
2953 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
2956 insert_insn_on_edge (gen_rtx_USE (VOIDmode
, const0_rtx
), e
);
2957 commit_edge_insertions ();
2962 /* Now add fake edges to the function exit for any non constant
2963 calls since there is no way that we can determine if they will
2966 for (i
= NUM_FIXED_BLOCKS
; i
< last_bb
; i
++)
2968 basic_block bb
= BASIC_BLOCK (i
);
2975 if (blocks
&& !TEST_BIT (blocks
, i
))
2978 for (insn
= BB_END (bb
); ; insn
= prev_insn
)
2980 prev_insn
= PREV_INSN (insn
);
2981 if (need_fake_edge_p (insn
))
2984 rtx split_at_insn
= insn
;
2986 /* Don't split the block between a call and an insn that should
2987 remain in the same block as the call. */
2989 while (split_at_insn
!= BB_END (bb
)
2990 && keep_with_call_p (NEXT_INSN (split_at_insn
)))
2991 split_at_insn
= NEXT_INSN (split_at_insn
);
2993 /* The handling above of the final block before the epilogue
2994 should be enough to verify that there is no edge to the exit
2995 block in CFG already. Calling make_edge in such case would
2996 cause us to mark that edge as fake and remove it later. */
2998 #ifdef ENABLE_CHECKING
2999 if (split_at_insn
== BB_END (bb
))
3001 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
3002 gcc_assert (e
== NULL
);
3006 /* Note that the following may create a new basic block
3007 and renumber the existing basic blocks. */
3008 if (split_at_insn
!= BB_END (bb
))
3010 e
= split_block (bb
, split_at_insn
);
3015 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
3018 if (insn
== BB_HEAD (bb
))
3024 verify_flow_info ();
3026 return blocks_split
;
3029 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
3030 the conditional branch target, SECOND_HEAD should be the fall-thru
3031 there is no need to handle this here the loop versioning code handles
3032 this. the reason for SECON_HEAD is that it is needed for condition
3033 in trees, and this should be of the same type since it is a hook. */
3035 rtl_lv_add_condition_to_bb (basic_block first_head
,
3036 basic_block second_head ATTRIBUTE_UNUSED
,
3037 basic_block cond_bb
, void *comp_rtx
)
3039 rtx label
, seq
, jump
;
3040 rtx op0
= XEXP ((rtx
)comp_rtx
, 0);
3041 rtx op1
= XEXP ((rtx
)comp_rtx
, 1);
3042 enum rtx_code comp
= GET_CODE ((rtx
)comp_rtx
);
3043 enum machine_mode mode
;
3046 label
= block_label (first_head
);
3047 mode
= GET_MODE (op0
);
3048 if (mode
== VOIDmode
)
3049 mode
= GET_MODE (op1
);
3052 op0
= force_operand (op0
, NULL_RTX
);
3053 op1
= force_operand (op1
, NULL_RTX
);
3054 do_compare_rtx_and_jump (op0
, op1
, comp
, 0,
3055 mode
, NULL_RTX
, NULL_RTX
, label
);
3056 jump
= get_last_insn ();
3057 JUMP_LABEL (jump
) = label
;
3058 LABEL_NUSES (label
)++;
3062 /* Add the new cond , in the new head. */
3063 emit_insn_after(seq
, BB_END(cond_bb
));
3067 /* Given a block B with unconditional branch at its end, get the
3068 store the return the branch edge and the fall-thru edge in
3069 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
3071 rtl_extract_cond_bb_edges (basic_block b
, edge
*branch_edge
,
3072 edge
*fallthru_edge
)
3074 edge e
= EDGE_SUCC (b
, 0);
3076 if (e
->flags
& EDGE_FALLTHRU
)
3079 *branch_edge
= EDGE_SUCC (b
, 1);
3084 *fallthru_edge
= EDGE_SUCC (b
, 1);
3089 init_rtl_bb_info (basic_block bb
)
3091 gcc_assert (!bb
->il
.rtl
);
3092 bb
->il
.rtl
= ggc_alloc_cleared (sizeof (struct rtl_bb_info
));
3096 /* Implementation of CFG manipulation for linearized RTL. */
3097 struct cfg_hooks rtl_cfg_hooks
= {
3099 rtl_verify_flow_info
,
3101 rtl_create_basic_block
,
3102 rtl_redirect_edge_and_branch
,
3103 rtl_redirect_edge_and_branch_force
,
3106 rtl_move_block_after
,
3107 rtl_can_merge_blocks
, /* can_merge_blocks_p */
3111 NULL
, /* can_duplicate_block_p */
3112 NULL
, /* duplicate_block */
3114 rtl_make_forwarder_block
,
3115 rtl_tidy_fallthru_edge
,
3116 rtl_block_ends_with_call_p
,
3117 rtl_block_ends_with_condjump_p
,
3118 rtl_flow_call_edges_add
,
3119 NULL
, /* execute_on_growing_pred */
3120 NULL
, /* execute_on_shrinking_pred */
3121 NULL
, /* duplicate loop for trees */
3122 NULL
, /* lv_add_condition_to_bb */
3123 NULL
, /* lv_adjust_loop_header_phi*/
3124 NULL
, /* extract_cond_bb_edges */
3125 NULL
/* flush_pending_stmts */
3128 /* Implementation of CFG manipulation for cfg layout RTL, where
3129 basic block connected via fallthru edges does not have to be adjacent.
3130 This representation will hopefully become the default one in future
3131 version of the compiler. */
3133 /* We do not want to declare these functions in a header file, since they
3134 should only be used through the cfghooks interface, and we do not want to
3135 move them here since it would require also moving quite a lot of related
3137 extern bool cfg_layout_can_duplicate_bb_p (basic_block
);
3138 extern basic_block
cfg_layout_duplicate_bb (basic_block
);
3140 struct cfg_hooks cfg_layout_rtl_cfg_hooks
= {
3142 rtl_verify_flow_info_1
,
3144 cfg_layout_create_basic_block
,
3145 cfg_layout_redirect_edge_and_branch
,
3146 cfg_layout_redirect_edge_and_branch_force
,
3147 cfg_layout_delete_block
,
3148 cfg_layout_split_block
,
3149 rtl_move_block_after
,
3150 cfg_layout_can_merge_blocks_p
,
3151 cfg_layout_merge_blocks
,
3154 cfg_layout_can_duplicate_bb_p
,
3155 cfg_layout_duplicate_bb
,
3156 cfg_layout_split_edge
,
3157 rtl_make_forwarder_block
,
3159 rtl_block_ends_with_call_p
,
3160 rtl_block_ends_with_condjump_p
,
3161 rtl_flow_call_edges_add
,
3162 NULL
, /* execute_on_growing_pred */
3163 NULL
, /* execute_on_shrinking_pred */
3164 duplicate_loop_to_header_edge
, /* duplicate loop for trees */
3165 rtl_lv_add_condition_to_bb
, /* lv_add_condition_to_bb */
3166 NULL
, /* lv_adjust_loop_header_phi*/
3167 rtl_extract_cond_bb_edges
, /* extract_cond_bb_edges */
3168 NULL
/* flush_pending_stmts */