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
);
67 static basic_block
rtl_split_edge (edge
);
68 static bool rtl_move_block_after (basic_block
, basic_block
);
69 static int rtl_verify_flow_info (void);
70 static basic_block
cfg_layout_split_block (basic_block
, void *);
71 static edge
cfg_layout_redirect_edge_and_branch (edge
, basic_block
);
72 static basic_block
cfg_layout_redirect_edge_and_branch_force (edge
, basic_block
);
73 static void cfg_layout_delete_block (basic_block
);
74 static void rtl_delete_block (basic_block
);
75 static basic_block
rtl_redirect_edge_and_branch_force (edge
, basic_block
);
76 static edge
rtl_redirect_edge_and_branch (edge
, basic_block
);
77 static basic_block
rtl_split_block (basic_block
, void *);
78 static void rtl_dump_bb (basic_block
, FILE *, int);
79 static int rtl_verify_flow_info_1 (void);
80 static void rtl_make_forwarder_block (edge
);
82 /* Return true if NOTE is not one of the ones that must be kept paired,
83 so that we may simply delete it. */
86 can_delete_note_p (rtx note
)
88 return (NOTE_LINE_NUMBER (note
) == NOTE_INSN_DELETED
89 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_BASIC_BLOCK
);
92 /* True if a given label can be deleted. */
95 can_delete_label_p (rtx label
)
97 return (!LABEL_PRESERVE_P (label
)
98 /* User declared labels must be preserved. */
99 && LABEL_NAME (label
) == 0
100 && !in_expr_list_p (forced_labels
, label
));
103 /* Delete INSN by patching it out. Return the next insn. */
106 delete_insn (rtx insn
)
108 rtx next
= NEXT_INSN (insn
);
110 bool really_delete
= true;
114 /* Some labels can't be directly removed from the INSN chain, as they
115 might be references via variables, constant pool etc.
116 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
117 if (! can_delete_label_p (insn
))
119 const char *name
= LABEL_NAME (insn
);
121 really_delete
= false;
122 PUT_CODE (insn
, NOTE
);
123 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
124 NOTE_DELETED_LABEL_NAME (insn
) = name
;
127 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
132 /* If this insn has already been deleted, something is very wrong. */
133 gcc_assert (!INSN_DELETED_P (insn
));
135 INSN_DELETED_P (insn
) = 1;
138 /* If deleting a jump, decrement the use count of the label. Deleting
139 the label itself should happen in the normal course of block merging. */
142 && LABEL_P (JUMP_LABEL (insn
)))
143 LABEL_NUSES (JUMP_LABEL (insn
))--;
145 /* Also if deleting an insn that references a label. */
148 while ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)) != NULL_RTX
149 && LABEL_P (XEXP (note
, 0)))
151 LABEL_NUSES (XEXP (note
, 0))--;
152 remove_note (insn
, note
);
157 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
158 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
160 rtx pat
= PATTERN (insn
);
161 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
162 int len
= XVECLEN (pat
, diff_vec_p
);
165 for (i
= 0; i
< len
; i
++)
167 rtx label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
169 /* When deleting code in bulk (e.g. removing many unreachable
170 blocks) we can delete a label that's a target of the vector
171 before deleting the vector itself. */
173 LABEL_NUSES (label
)--;
180 /* Like delete_insn but also purge dead edges from BB. */
182 delete_insn_and_edges (rtx insn
)
188 && BLOCK_FOR_INSN (insn
)
189 && BB_END (BLOCK_FOR_INSN (insn
)) == insn
)
191 x
= delete_insn (insn
);
193 purge_dead_edges (BLOCK_FOR_INSN (insn
));
197 /* Unlink a chain of insns between START and FINISH, leaving notes
198 that must be paired. */
201 delete_insn_chain (rtx start
, rtx finish
)
205 /* Unchain the insns one by one. It would be quicker to delete all of these
206 with a single unchaining, rather than one at a time, but we need to keep
210 next
= NEXT_INSN (start
);
211 if (NOTE_P (start
) && !can_delete_note_p (start
))
214 next
= delete_insn (start
);
222 /* Like delete_insn but also purge dead edges from BB. */
224 delete_insn_chain_and_edges (rtx first
, rtx last
)
229 && BLOCK_FOR_INSN (last
)
230 && BB_END (BLOCK_FOR_INSN (last
)) == last
)
232 delete_insn_chain (first
, last
);
234 purge_dead_edges (BLOCK_FOR_INSN (last
));
237 /* Create a new basic block consisting of the instructions between HEAD and END
238 inclusive. This function is designed to allow fast BB construction - reuses
239 the note and basic block struct in BB_NOTE, if any and do not grow
240 BASIC_BLOCK chain and should be used directly only by CFG construction code.
241 END can be NULL in to create new empty basic block before HEAD. Both END
242 and HEAD can be NULL to create basic block at the end of INSN chain.
243 AFTER is the basic block we should be put after. */
246 create_basic_block_structure (rtx head
, rtx end
, rtx bb_note
, basic_block after
)
251 && (bb
= NOTE_BASIC_BLOCK (bb_note
)) != NULL
254 /* If we found an existing note, thread it back onto the chain. */
262 after
= PREV_INSN (head
);
266 if (after
!= bb_note
&& NEXT_INSN (after
) != bb_note
)
267 reorder_insns_nobb (bb_note
, bb_note
, after
);
271 /* Otherwise we must create a note and a basic block structure. */
275 init_rtl_bb_info (bb
);
278 = emit_note_after (NOTE_INSN_BASIC_BLOCK
, get_last_insn ());
279 else if (LABEL_P (head
) && end
)
281 bb_note
= emit_note_after (NOTE_INSN_BASIC_BLOCK
, head
);
287 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
, head
);
293 NOTE_BASIC_BLOCK (bb_note
) = bb
;
296 /* Always include the bb note in the block. */
297 if (NEXT_INSN (end
) == bb_note
)
302 bb
->index
= last_basic_block
++;
303 bb
->flags
= BB_NEW
| BB_RTL
;
304 link_block (bb
, after
);
305 SET_BASIC_BLOCK (bb
->index
, bb
);
306 update_bb_for_insn (bb
);
307 BB_SET_PARTITION (bb
, BB_UNPARTITIONED
);
309 /* Tag the block so that we know it has been used when considering
310 other basic block notes. */
316 /* Create new basic block consisting of instructions in between HEAD and END
317 and place it to the BB chain after block AFTER. END can be NULL in to
318 create new empty basic block before HEAD. Both END and HEAD can be NULL to
319 create basic block at the end of INSN chain. */
322 rtl_create_basic_block (void *headp
, void *endp
, basic_block after
)
324 rtx head
= headp
, end
= endp
;
327 /* Grow the basic block array if needed. */
328 if ((size_t) last_basic_block
>= VEC_length (basic_block
, basic_block_info
))
330 size_t old_size
= VEC_length (basic_block
, basic_block_info
);
331 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
333 VEC_safe_grow (basic_block
, gc
, basic_block_info
, new_size
);
334 p
= VEC_address (basic_block
, basic_block_info
);
335 memset (&p
[old_size
], 0, sizeof (basic_block
) * (new_size
- old_size
));
340 bb
= create_basic_block_structure (head
, end
, NULL
, after
);
346 cfg_layout_create_basic_block (void *head
, void *end
, basic_block after
)
348 basic_block newbb
= rtl_create_basic_block (head
, end
, after
);
353 /* Delete the insns in a (non-live) block. We physically delete every
354 non-deleted-note insn, and update the flow graph appropriately.
356 Return nonzero if we deleted an exception handler. */
358 /* ??? Preserving all such notes strikes me as wrong. It would be nice
359 to post-process the stream to remove empty blocks, loops, ranges, etc. */
362 rtl_delete_block (basic_block b
)
366 /* If the head of this block is a CODE_LABEL, then it might be the
367 label for an exception handler which can't be reached. We need
368 to remove the label from the exception_handler_label list. */
371 maybe_remove_eh_handler (insn
);
373 end
= get_last_bb_insn (b
);
375 /* Selectively delete the entire chain. */
377 delete_insn_chain (insn
, end
);
378 if (b
->il
.rtl
->global_live_at_start
)
380 FREE_REG_SET (b
->il
.rtl
->global_live_at_start
);
381 FREE_REG_SET (b
->il
.rtl
->global_live_at_end
);
382 b
->il
.rtl
->global_live_at_start
= NULL
;
383 b
->il
.rtl
->global_live_at_end
= NULL
;
387 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
390 compute_bb_for_insn (void)
396 rtx end
= BB_END (bb
);
399 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
401 BLOCK_FOR_INSN (insn
) = bb
;
408 /* Release the basic_block_for_insn array. */
411 free_bb_for_insn (void)
414 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
415 if (!BARRIER_P (insn
))
416 BLOCK_FOR_INSN (insn
) = NULL
;
420 struct tree_opt_pass pass_free_cfg
=
424 free_bb_for_insn
, /* execute */
427 0, /* static_pass_number */
429 0, /* properties_required */
430 0, /* properties_provided */
431 PROP_cfg
, /* properties_destroyed */
432 0, /* todo_flags_start */
433 0, /* todo_flags_finish */
437 /* Return RTX to emit after when we want to emit code on the entry of function. */
439 entry_of_function (void)
441 return (n_basic_blocks
> NUM_FIXED_BLOCKS
?
442 BB_HEAD (ENTRY_BLOCK_PTR
->next_bb
) : get_insns ());
445 /* Emit INSN at the entry point of the function, ensuring that it is only
446 executed once per function. */
448 emit_insn_at_entry (rtx insn
)
450 edge_iterator ei
= ei_start (ENTRY_BLOCK_PTR
->succs
);
451 edge e
= ei_safe_edge (ei
);
452 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
454 insert_insn_on_edge (insn
, e
);
455 commit_edge_insertions ();
458 /* Update insns block within BB. */
461 update_bb_for_insn (basic_block bb
)
465 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
467 if (!BARRIER_P (insn
))
468 set_block_for_insn (insn
, bb
);
469 if (insn
== BB_END (bb
))
474 /* Creates a new basic block just after basic block B by splitting
475 everything after specified instruction I. */
478 rtl_split_block (basic_block bb
, void *insnp
)
487 insn
= first_insn_after_basic_block_note (bb
);
490 insn
= PREV_INSN (insn
);
492 insn
= get_last_insn ();
495 /* We probably should check type of the insn so that we do not create
496 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
498 if (insn
== BB_END (bb
))
499 emit_note_after (NOTE_INSN_DELETED
, insn
);
501 /* Create the new basic block. */
502 new_bb
= create_basic_block (NEXT_INSN (insn
), BB_END (bb
), bb
);
503 BB_COPY_PARTITION (new_bb
, bb
);
506 /* Redirect the outgoing edges. */
507 new_bb
->succs
= bb
->succs
;
509 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
512 if (bb
->il
.rtl
->global_live_at_start
)
514 new_bb
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
515 new_bb
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
516 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_end
, bb
->il
.rtl
->global_live_at_end
);
518 /* We now have to calculate which registers are live at the end
519 of the split basic block and at the start of the new basic
520 block. Start with those registers that are known to be live
521 at the end of the original basic block and get
522 propagate_block to determine which registers are live. */
523 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_start
, bb
->il
.rtl
->global_live_at_end
);
524 propagate_block (new_bb
, new_bb
->il
.rtl
->global_live_at_start
, NULL
, NULL
, 0);
525 COPY_REG_SET (bb
->il
.rtl
->global_live_at_end
,
526 new_bb
->il
.rtl
->global_live_at_start
);
527 #ifdef HAVE_conditional_execution
528 /* In the presence of conditional execution we are not able to update
529 liveness precisely. */
530 if (reload_completed
)
532 bb
->flags
|= BB_DIRTY
;
533 new_bb
->flags
|= BB_DIRTY
;
541 /* Blocks A and B are to be merged into a single block A. The insns
542 are already contiguous. */
545 rtl_merge_blocks (basic_block a
, basic_block b
)
547 rtx b_head
= BB_HEAD (b
), b_end
= BB_END (b
), a_end
= BB_END (a
);
548 rtx del_first
= NULL_RTX
, del_last
= NULL_RTX
;
551 /* If there was a CODE_LABEL beginning B, delete it. */
552 if (LABEL_P (b_head
))
554 /* This might have been an EH label that no longer has incoming
555 EH edges. Update data structures to match. */
556 maybe_remove_eh_handler (b_head
);
558 /* Detect basic blocks with nothing but a label. This can happen
559 in particular at the end of a function. */
563 del_first
= del_last
= b_head
;
564 b_head
= NEXT_INSN (b_head
);
567 /* Delete the basic block note and handle blocks containing just that
569 if (NOTE_INSN_BASIC_BLOCK_P (b_head
))
577 b_head
= NEXT_INSN (b_head
);
580 /* If there was a jump out of A, delete it. */
585 for (prev
= PREV_INSN (a_end
); ; prev
= PREV_INSN (prev
))
587 || NOTE_LINE_NUMBER (prev
) == NOTE_INSN_BASIC_BLOCK
588 || prev
== BB_HEAD (a
))
594 /* If this was a conditional jump, we need to also delete
595 the insn that set cc0. */
596 if (only_sets_cc0_p (prev
))
600 prev
= prev_nonnote_insn (prev
);
607 a_end
= PREV_INSN (del_first
);
609 else if (BARRIER_P (NEXT_INSN (a_end
)))
610 del_first
= NEXT_INSN (a_end
);
612 /* Delete everything marked above as well as crap that might be
613 hanging out between the two blocks. */
615 delete_insn_chain (del_first
, del_last
);
617 /* Reassociate the insns of B with A. */
622 for (x
= a_end
; x
!= b_end
; x
= NEXT_INSN (x
))
623 set_block_for_insn (x
, a
);
625 set_block_for_insn (b_end
, a
);
631 a
->il
.rtl
->global_live_at_end
= b
->il
.rtl
->global_live_at_end
;
634 /* Return true when block A and B can be merged. */
636 rtl_can_merge_blocks (basic_block a
,basic_block b
)
638 /* If we are partitioning hot/cold basic blocks, we don't want to
639 mess up unconditional or indirect jumps that cross between hot
642 Basic block partitioning may result in some jumps that appear to
643 be optimizable (or blocks that appear to be mergeable), but which really
644 must be left untouched (they are required to make it safely across
645 partition boundaries). See the comments at the top of
646 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
648 if (BB_PARTITION (a
) != BB_PARTITION (b
))
651 /* There must be exactly one edge in between the blocks. */
652 return (single_succ_p (a
)
653 && single_succ (a
) == b
656 /* Must be simple edge. */
657 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
659 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
660 /* If the jump insn has side effects,
661 we can't kill the edge. */
662 && (!JUMP_P (BB_END (a
))
664 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
667 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
671 block_label (basic_block block
)
673 if (block
== EXIT_BLOCK_PTR
)
676 if (!LABEL_P (BB_HEAD (block
)))
678 BB_HEAD (block
) = emit_label_before (gen_label_rtx (), BB_HEAD (block
));
681 return BB_HEAD (block
);
684 /* Attempt to perform edge redirection by replacing possibly complex jump
685 instruction by unconditional jump or removing jump completely. This can
686 apply only if all edges now point to the same block. The parameters and
687 return values are equivalent to redirect_edge_and_branch. */
690 try_redirect_by_replacing_jump (edge e
, basic_block target
, bool in_cfglayout
)
692 basic_block src
= e
->src
;
693 rtx insn
= BB_END (src
), kill_from
;
697 /* If we are partitioning hot/cold basic blocks, we don't want to
698 mess up unconditional or indirect jumps that cross between hot
701 Basic block partitioning may result in some jumps that appear to
702 be optimizable (or blocks that appear to be mergeable), but which really
703 must be left untouched (they are required to make it safely across
704 partition boundaries). See the comments at the top of
705 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
707 if (find_reg_note (insn
, REG_CROSSING_JUMP
, NULL_RTX
)
708 || BB_PARTITION (src
) != BB_PARTITION (target
))
711 /* We can replace or remove a complex jump only when we have exactly
712 two edges. Also, if we have exactly one outgoing edge, we can
714 if (EDGE_COUNT (src
->succs
) >= 3
715 /* Verify that all targets will be TARGET. Specifically, the
716 edge that is not E must also go to TARGET. */
717 || (EDGE_COUNT (src
->succs
) == 2
718 && EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
))
721 if (!onlyjump_p (insn
))
723 if ((!optimize
|| reload_completed
) && tablejump_p (insn
, NULL
, NULL
))
726 /* Avoid removing branch with side effects. */
727 set
= single_set (insn
);
728 if (!set
|| side_effects_p (set
))
731 /* In case we zap a conditional jump, we'll need to kill
732 the cc0 setter too. */
735 if (reg_mentioned_p (cc0_rtx
, PATTERN (insn
)))
736 kill_from
= PREV_INSN (insn
);
739 /* See if we can create the fallthru edge. */
740 if (in_cfglayout
|| can_fallthru (src
, target
))
743 fprintf (dump_file
, "Removing jump %i.\n", INSN_UID (insn
));
746 /* Selectively unlink whole insn chain. */
749 rtx insn
= src
->il
.rtl
->footer
;
751 delete_insn_chain (kill_from
, BB_END (src
));
753 /* Remove barriers but keep jumptables. */
756 if (BARRIER_P (insn
))
758 if (PREV_INSN (insn
))
759 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
761 src
->il
.rtl
->footer
= NEXT_INSN (insn
);
762 if (NEXT_INSN (insn
))
763 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
767 insn
= NEXT_INSN (insn
);
771 delete_insn_chain (kill_from
, PREV_INSN (BB_HEAD (target
)));
774 /* If this already is simplejump, redirect it. */
775 else if (simplejump_p (insn
))
777 if (e
->dest
== target
)
780 fprintf (dump_file
, "Redirecting jump %i from %i to %i.\n",
781 INSN_UID (insn
), e
->dest
->index
, target
->index
);
782 if (!redirect_jump (insn
, block_label (target
), 0))
784 gcc_assert (target
== EXIT_BLOCK_PTR
);
789 /* Cannot do anything for target exit block. */
790 else if (target
== EXIT_BLOCK_PTR
)
793 /* Or replace possibly complicated jump insn by simple jump insn. */
796 rtx target_label
= block_label (target
);
797 rtx barrier
, label
, table
;
799 emit_jump_insn_after_noloc (gen_jump (target_label
), insn
);
800 JUMP_LABEL (BB_END (src
)) = target_label
;
801 LABEL_NUSES (target_label
)++;
803 fprintf (dump_file
, "Replacing insn %i by jump %i\n",
804 INSN_UID (insn
), INSN_UID (BB_END (src
)));
807 delete_insn_chain (kill_from
, insn
);
809 /* Recognize a tablejump that we are converting to a
810 simple jump and remove its associated CODE_LABEL
811 and ADDR_VEC or ADDR_DIFF_VEC. */
812 if (tablejump_p (insn
, &label
, &table
))
813 delete_insn_chain (label
, table
);
815 barrier
= next_nonnote_insn (BB_END (src
));
816 if (!barrier
|| !BARRIER_P (barrier
))
817 emit_barrier_after (BB_END (src
));
820 if (barrier
!= NEXT_INSN (BB_END (src
)))
822 /* Move the jump before barrier so that the notes
823 which originally were or were created before jump table are
824 inside the basic block. */
825 rtx new_insn
= BB_END (src
);
828 for (tmp
= NEXT_INSN (BB_END (src
)); tmp
!= barrier
;
829 tmp
= NEXT_INSN (tmp
))
830 set_block_for_insn (tmp
, src
);
832 NEXT_INSN (PREV_INSN (new_insn
)) = NEXT_INSN (new_insn
);
833 PREV_INSN (NEXT_INSN (new_insn
)) = PREV_INSN (new_insn
);
835 NEXT_INSN (new_insn
) = barrier
;
836 NEXT_INSN (PREV_INSN (barrier
)) = new_insn
;
838 PREV_INSN (new_insn
) = PREV_INSN (barrier
);
839 PREV_INSN (barrier
) = new_insn
;
844 /* Keep only one edge out and set proper flags. */
845 if (!single_succ_p (src
))
847 gcc_assert (single_succ_p (src
));
849 e
= single_succ_edge (src
);
851 e
->flags
= EDGE_FALLTHRU
;
855 e
->probability
= REG_BR_PROB_BASE
;
856 e
->count
= src
->count
;
858 if (e
->dest
!= target
)
859 redirect_edge_succ (e
, target
);
864 /* Redirect edge representing branch of (un)conditional jump or tablejump,
867 redirect_branch_edge (edge e
, basic_block target
)
870 rtx old_label
= BB_HEAD (e
->dest
);
871 basic_block src
= e
->src
;
872 rtx insn
= BB_END (src
);
874 /* We can only redirect non-fallthru edges of jump insn. */
875 if (e
->flags
& EDGE_FALLTHRU
)
877 else if (!JUMP_P (insn
))
880 /* Recognize a tablejump and adjust all matching cases. */
881 if (tablejump_p (insn
, NULL
, &tmp
))
885 rtx new_label
= block_label (target
);
887 if (target
== EXIT_BLOCK_PTR
)
889 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
890 vec
= XVEC (PATTERN (tmp
), 0);
892 vec
= XVEC (PATTERN (tmp
), 1);
894 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
895 if (XEXP (RTVEC_ELT (vec
, j
), 0) == old_label
)
897 RTVEC_ELT (vec
, j
) = gen_rtx_LABEL_REF (Pmode
, new_label
);
898 --LABEL_NUSES (old_label
);
899 ++LABEL_NUSES (new_label
);
902 /* Handle casesi dispatch insns. */
903 if ((tmp
= single_set (insn
)) != NULL
904 && SET_DEST (tmp
) == pc_rtx
905 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
906 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
907 && XEXP (XEXP (SET_SRC (tmp
), 2), 0) == old_label
)
909 XEXP (SET_SRC (tmp
), 2) = gen_rtx_LABEL_REF (Pmode
,
911 --LABEL_NUSES (old_label
);
912 ++LABEL_NUSES (new_label
);
917 /* ?? We may play the games with moving the named labels from
918 one basic block to the other in case only one computed_jump is
920 if (computed_jump_p (insn
)
921 /* A return instruction can't be redirected. */
922 || returnjump_p (insn
))
925 /* If the insn doesn't go where we think, we're confused. */
926 gcc_assert (JUMP_LABEL (insn
) == old_label
);
928 /* If the substitution doesn't succeed, die. This can happen
929 if the back end emitted unrecognizable instructions or if
930 target is exit block on some arches. */
931 if (!redirect_jump (insn
, block_label (target
), 0))
933 gcc_assert (target
== EXIT_BLOCK_PTR
);
939 fprintf (dump_file
, "Edge %i->%i redirected to %i\n",
940 e
->src
->index
, e
->dest
->index
, target
->index
);
942 if (e
->dest
!= target
)
943 e
= redirect_edge_succ_nodup (e
, target
);
947 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
948 expense of adding new instructions or reordering basic blocks.
950 Function can be also called with edge destination equivalent to the TARGET.
951 Then it should try the simplifications and do nothing if none is possible.
953 Return edge representing the branch if transformation succeeded. Return NULL
955 We still return NULL in case E already destinated TARGET and we didn't
956 managed to simplify instruction stream. */
959 rtl_redirect_edge_and_branch (edge e
, basic_block target
)
962 basic_block src
= e
->src
;
964 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
967 if (e
->dest
== target
)
970 if ((ret
= try_redirect_by_replacing_jump (e
, target
, false)) != NULL
)
972 src
->flags
|= BB_DIRTY
;
976 ret
= redirect_branch_edge (e
, target
);
980 src
->flags
|= BB_DIRTY
;
984 /* Like force_nonfallthru below, but additionally performs redirection
985 Used by redirect_edge_and_branch_force. */
988 force_nonfallthru_and_redirect (edge e
, basic_block target
)
990 basic_block jump_block
, new_bb
= NULL
, src
= e
->src
;
993 int abnormal_edge_flags
= 0;
995 /* In the case the last instruction is conditional jump to the next
996 instruction, first redirect the jump itself and then continue
997 by creating a basic block afterwards to redirect fallthru edge. */
998 if (e
->src
!= ENTRY_BLOCK_PTR
&& e
->dest
!= EXIT_BLOCK_PTR
999 && any_condjump_p (BB_END (e
->src
))
1000 && JUMP_LABEL (BB_END (e
->src
)) == BB_HEAD (e
->dest
))
1003 edge b
= unchecked_make_edge (e
->src
, target
, 0);
1006 redirected
= redirect_jump (BB_END (e
->src
), block_label (target
), 0);
1007 gcc_assert (redirected
);
1009 note
= find_reg_note (BB_END (e
->src
), REG_BR_PROB
, NULL_RTX
);
1012 int prob
= INTVAL (XEXP (note
, 0));
1014 b
->probability
= prob
;
1015 b
->count
= e
->count
* prob
/ REG_BR_PROB_BASE
;
1016 e
->probability
-= e
->probability
;
1017 e
->count
-= b
->count
;
1018 if (e
->probability
< 0)
1025 if (e
->flags
& EDGE_ABNORMAL
)
1027 /* Irritating special case - fallthru edge to the same block as abnormal
1029 We can't redirect abnormal edge, but we still can split the fallthru
1030 one and create separate abnormal edge to original destination.
1031 This allows bb-reorder to make such edge non-fallthru. */
1032 gcc_assert (e
->dest
== target
);
1033 abnormal_edge_flags
= e
->flags
& ~(EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
);
1034 e
->flags
&= EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
;
1038 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1039 if (e
->src
== ENTRY_BLOCK_PTR
)
1041 /* We can't redirect the entry block. Create an empty block
1042 at the start of the function which we use to add the new
1048 basic_block bb
= create_basic_block (BB_HEAD (e
->dest
), NULL
, ENTRY_BLOCK_PTR
);
1050 /* Change the existing edge's source to be the new block, and add
1051 a new edge from the entry block to the new block. */
1053 for (ei
= ei_start (ENTRY_BLOCK_PTR
->succs
); (tmp
= ei_safe_edge (ei
)); )
1057 VEC_unordered_remove (edge
, ENTRY_BLOCK_PTR
->succs
, ei
.index
);
1067 VEC_safe_push (edge
, gc
, bb
->succs
, e
);
1068 make_single_succ_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_FALLTHRU
);
1072 if (EDGE_COUNT (e
->src
->succs
) >= 2 || abnormal_edge_flags
)
1074 /* Create the new structures. */
1076 /* If the old block ended with a tablejump, skip its table
1077 by searching forward from there. Otherwise start searching
1078 forward from the last instruction of the old block. */
1079 if (!tablejump_p (BB_END (e
->src
), NULL
, ¬e
))
1080 note
= BB_END (e
->src
);
1081 note
= NEXT_INSN (note
);
1083 jump_block
= create_basic_block (note
, NULL
, e
->src
);
1084 jump_block
->count
= e
->count
;
1085 jump_block
->frequency
= EDGE_FREQUENCY (e
);
1086 jump_block
->loop_depth
= target
->loop_depth
;
1088 if (target
->il
.rtl
->global_live_at_start
)
1090 jump_block
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1091 jump_block
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1092 COPY_REG_SET (jump_block
->il
.rtl
->global_live_at_start
,
1093 target
->il
.rtl
->global_live_at_start
);
1094 COPY_REG_SET (jump_block
->il
.rtl
->global_live_at_end
,
1095 target
->il
.rtl
->global_live_at_start
);
1098 /* Make sure new block ends up in correct hot/cold section. */
1100 BB_COPY_PARTITION (jump_block
, e
->src
);
1101 if (flag_reorder_blocks_and_partition
1102 && targetm
.have_named_sections
1103 && JUMP_P (BB_END (jump_block
))
1104 && !any_condjump_p (BB_END (jump_block
))
1105 && (EDGE_SUCC (jump_block
, 0)->flags
& EDGE_CROSSING
))
1106 REG_NOTES (BB_END (jump_block
)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP
,
1113 new_edge
= make_edge (e
->src
, jump_block
, EDGE_FALLTHRU
);
1114 new_edge
->probability
= e
->probability
;
1115 new_edge
->count
= e
->count
;
1117 /* Redirect old edge. */
1118 redirect_edge_pred (e
, jump_block
);
1119 e
->probability
= REG_BR_PROB_BASE
;
1121 new_bb
= jump_block
;
1124 jump_block
= e
->src
;
1126 e
->flags
&= ~EDGE_FALLTHRU
;
1127 if (target
== EXIT_BLOCK_PTR
)
1130 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block
));
1137 rtx label
= block_label (target
);
1138 emit_jump_insn_after_noloc (gen_jump (label
), BB_END (jump_block
));
1139 JUMP_LABEL (BB_END (jump_block
)) = label
;
1140 LABEL_NUSES (label
)++;
1143 emit_barrier_after (BB_END (jump_block
));
1144 redirect_edge_succ_nodup (e
, target
);
1146 if (abnormal_edge_flags
)
1147 make_edge (src
, target
, abnormal_edge_flags
);
1152 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1153 (and possibly create new basic block) to make edge non-fallthru.
1154 Return newly created BB or NULL if none. */
1157 force_nonfallthru (edge e
)
1159 return force_nonfallthru_and_redirect (e
, e
->dest
);
1162 /* Redirect edge even at the expense of creating new jump insn or
1163 basic block. Return new basic block if created, NULL otherwise.
1164 Conversion must be possible. */
1167 rtl_redirect_edge_and_branch_force (edge e
, basic_block target
)
1169 if (redirect_edge_and_branch (e
, target
)
1170 || e
->dest
== target
)
1173 /* In case the edge redirection failed, try to force it to be non-fallthru
1174 and redirect newly created simplejump. */
1175 e
->src
->flags
|= BB_DIRTY
;
1176 return force_nonfallthru_and_redirect (e
, target
);
1179 /* The given edge should potentially be a fallthru edge. If that is in
1180 fact true, delete the jump and barriers that are in the way. */
1183 rtl_tidy_fallthru_edge (edge e
)
1186 basic_block b
= e
->src
, c
= b
->next_bb
;
1188 /* ??? In a late-running flow pass, other folks may have deleted basic
1189 blocks by nopping out blocks, leaving multiple BARRIERs between here
1190 and the target label. They ought to be chastised and fixed.
1192 We can also wind up with a sequence of undeletable labels between
1193 one block and the next.
1195 So search through a sequence of barriers, labels, and notes for
1196 the head of block C and assert that we really do fall through. */
1198 for (q
= NEXT_INSN (BB_END (b
)); q
!= BB_HEAD (c
); q
= NEXT_INSN (q
))
1202 /* Remove what will soon cease being the jump insn from the source block.
1203 If block B consisted only of this single jump, turn it into a deleted
1208 && (any_uncondjump_p (q
)
1209 || single_succ_p (b
)))
1212 /* If this was a conditional jump, we need to also delete
1213 the insn that set cc0. */
1214 if (any_condjump_p (q
) && only_sets_cc0_p (PREV_INSN (q
)))
1221 /* Selectively unlink the sequence. */
1222 if (q
!= PREV_INSN (BB_HEAD (c
)))
1223 delete_insn_chain (NEXT_INSN (q
), PREV_INSN (BB_HEAD (c
)));
1225 e
->flags
|= EDGE_FALLTHRU
;
1228 /* Should move basic block BB after basic block AFTER. NIY. */
1231 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED
,
1232 basic_block after ATTRIBUTE_UNUSED
)
1237 /* Split a (typically critical) edge. Return the new block.
1238 The edge must not be abnormal.
1240 ??? The code generally expects to be called on critical edges.
1241 The case of a block ending in an unconditional jump to a
1242 block with multiple predecessors is not handled optimally. */
1245 rtl_split_edge (edge edge_in
)
1250 /* Abnormal edges cannot be split. */
1251 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
1253 /* We are going to place the new block in front of edge destination.
1254 Avoid existence of fallthru predecessors. */
1255 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1260 FOR_EACH_EDGE (e
, ei
, edge_in
->dest
->preds
)
1261 if (e
->flags
& EDGE_FALLTHRU
)
1265 force_nonfallthru (e
);
1268 /* Create the basic block note. */
1269 if (edge_in
->dest
!= EXIT_BLOCK_PTR
)
1270 before
= BB_HEAD (edge_in
->dest
);
1274 /* If this is a fall through edge to the exit block, the blocks might be
1275 not adjacent, and the right place is the after the source. */
1276 if (edge_in
->flags
& EDGE_FALLTHRU
&& edge_in
->dest
== EXIT_BLOCK_PTR
)
1278 before
= NEXT_INSN (BB_END (edge_in
->src
));
1279 bb
= create_basic_block (before
, NULL
, edge_in
->src
);
1280 BB_COPY_PARTITION (bb
, edge_in
->src
);
1284 bb
= create_basic_block (before
, NULL
, edge_in
->dest
->prev_bb
);
1285 /* ??? Why not edge_in->dest->prev_bb here? */
1286 BB_COPY_PARTITION (bb
, edge_in
->dest
);
1289 /* ??? This info is likely going to be out of date very soon. */
1290 if (edge_in
->dest
->il
.rtl
->global_live_at_start
)
1292 bb
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1293 bb
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1294 COPY_REG_SET (bb
->il
.rtl
->global_live_at_start
,
1295 edge_in
->dest
->il
.rtl
->global_live_at_start
);
1296 COPY_REG_SET (bb
->il
.rtl
->global_live_at_end
,
1297 edge_in
->dest
->il
.rtl
->global_live_at_start
);
1300 make_single_succ_edge (bb
, edge_in
->dest
, EDGE_FALLTHRU
);
1302 /* For non-fallthru edges, we must adjust the predecessor's
1303 jump instruction to target our new block. */
1304 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1306 edge redirected
= redirect_edge_and_branch (edge_in
, bb
);
1307 gcc_assert (redirected
);
1310 redirect_edge_succ (edge_in
, bb
);
1315 /* Queue instructions for insertion on an edge between two basic blocks.
1316 The new instructions and basic blocks (if any) will not appear in the
1317 CFG until commit_edge_insertions is called. */
1320 insert_insn_on_edge (rtx pattern
, edge e
)
1322 /* We cannot insert instructions on an abnormal critical edge.
1323 It will be easier to find the culprit if we die now. */
1324 gcc_assert (!((e
->flags
& EDGE_ABNORMAL
) && EDGE_CRITICAL_P (e
)));
1326 if (e
->insns
.r
== NULL_RTX
)
1329 push_to_sequence (e
->insns
.r
);
1331 emit_insn (pattern
);
1333 e
->insns
.r
= get_insns ();
1337 /* Update the CFG for the instructions queued on edge E. */
1340 commit_one_edge_insertion (edge e
)
1342 rtx before
= NULL_RTX
, after
= NULL_RTX
, insns
, tmp
, last
;
1343 basic_block bb
= NULL
;
1345 /* Pull the insns off the edge now since the edge might go away. */
1347 e
->insns
.r
= NULL_RTX
;
1349 if (!before
&& !after
)
1351 /* Figure out where to put these things. If the destination has
1352 one predecessor, insert there. Except for the exit block. */
1353 if (single_pred_p (e
->dest
) && e
->dest
!= EXIT_BLOCK_PTR
)
1357 /* Get the location correct wrt a code label, and "nice" wrt
1358 a basic block note, and before everything else. */
1361 tmp
= NEXT_INSN (tmp
);
1362 if (NOTE_INSN_BASIC_BLOCK_P (tmp
))
1363 tmp
= NEXT_INSN (tmp
);
1364 if (tmp
== BB_HEAD (bb
))
1367 after
= PREV_INSN (tmp
);
1369 after
= get_last_insn ();
1372 /* If the source has one successor and the edge is not abnormal,
1373 insert there. Except for the entry block. */
1374 else if ((e
->flags
& EDGE_ABNORMAL
) == 0
1375 && single_succ_p (e
->src
)
1376 && e
->src
!= ENTRY_BLOCK_PTR
)
1380 /* It is possible to have a non-simple jump here. Consider a target
1381 where some forms of unconditional jumps clobber a register. This
1382 happens on the fr30 for example.
1384 We know this block has a single successor, so we can just emit
1385 the queued insns before the jump. */
1386 if (JUMP_P (BB_END (bb
)))
1387 before
= BB_END (bb
);
1390 /* We'd better be fallthru, or we've lost track of
1392 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1394 after
= BB_END (bb
);
1397 /* Otherwise we must split the edge. */
1400 bb
= split_edge (e
);
1401 after
= BB_END (bb
);
1403 if (flag_reorder_blocks_and_partition
1404 && targetm
.have_named_sections
1405 && e
->src
!= ENTRY_BLOCK_PTR
1406 && BB_PARTITION (e
->src
) == BB_COLD_PARTITION
1407 && !(e
->flags
& EDGE_CROSSING
))
1409 rtx bb_note
, cur_insn
;
1412 for (cur_insn
= BB_HEAD (bb
); cur_insn
!= NEXT_INSN (BB_END (bb
));
1413 cur_insn
= NEXT_INSN (cur_insn
))
1414 if (NOTE_P (cur_insn
)
1415 && NOTE_LINE_NUMBER (cur_insn
) == NOTE_INSN_BASIC_BLOCK
)
1421 if (JUMP_P (BB_END (bb
))
1422 && !any_condjump_p (BB_END (bb
))
1423 && (single_succ_edge (bb
)->flags
& EDGE_CROSSING
))
1424 REG_NOTES (BB_END (bb
)) = gen_rtx_EXPR_LIST
1425 (REG_CROSSING_JUMP
, NULL_RTX
, REG_NOTES (BB_END (bb
)));
1430 /* Now that we've found the spot, do the insertion. */
1434 emit_insn_before_noloc (insns
, before
);
1435 last
= prev_nonnote_insn (before
);
1438 last
= emit_insn_after_noloc (insns
, after
);
1440 if (returnjump_p (last
))
1442 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1443 This is not currently a problem because this only happens
1444 for the (single) epilogue, which already has a fallthru edge
1447 e
= single_succ_edge (bb
);
1448 gcc_assert (e
->dest
== EXIT_BLOCK_PTR
1449 && single_succ_p (bb
) && (e
->flags
& EDGE_FALLTHRU
));
1451 e
->flags
&= ~EDGE_FALLTHRU
;
1452 emit_barrier_after (last
);
1455 delete_insn (before
);
1458 gcc_assert (!JUMP_P (last
));
1460 /* Mark the basic block for find_many_sub_basic_blocks. */
1461 if (current_ir_type () != IR_RTL_CFGLAYOUT
)
1465 /* Update the CFG for all queued instructions. */
1468 commit_edge_insertions (void)
1472 bool changed
= false;
1474 #ifdef ENABLE_CHECKING
1475 verify_flow_info ();
1478 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1483 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1487 commit_one_edge_insertion (e
);
1494 /* In the old rtl CFG API, it was OK to insert control flow on an
1495 edge, apparently? In cfglayout mode, this will *not* work, and
1496 the caller is responsible for making sure that control flow is
1497 valid at all times. */
1498 if (current_ir_type () == IR_RTL_CFGLAYOUT
)
1501 blocks
= sbitmap_alloc (last_basic_block
);
1502 sbitmap_zero (blocks
);
1506 SET_BIT (blocks
, bb
->index
);
1507 /* Check for forgotten bb->aux values before commit_edge_insertions
1509 gcc_assert (bb
->aux
== &bb
->aux
);
1512 find_many_sub_basic_blocks (blocks
);
1513 sbitmap_free (blocks
);
1516 /* Print out RTL-specific basic block information (live information
1517 at start and end). */
1520 rtl_dump_bb (basic_block bb
, FILE *outf
, int indent
)
1526 s_indent
= alloca ((size_t) indent
+ 1);
1527 memset (s_indent
, ' ', (size_t) indent
);
1528 s_indent
[indent
] = '\0';
1530 fprintf (outf
, ";;%s Registers live at start: ", s_indent
);
1531 dump_regset (bb
->il
.rtl
->global_live_at_start
, outf
);
1534 for (insn
= BB_HEAD (bb
), last
= NEXT_INSN (BB_END (bb
)); insn
!= last
;
1535 insn
= NEXT_INSN (insn
))
1536 print_rtl_single (outf
, insn
);
1538 fprintf (outf
, ";;%s Registers live at end: ", s_indent
);
1539 dump_regset (bb
->il
.rtl
->global_live_at_end
, outf
);
1543 /* Like print_rtl, but also print out live information for the start of each
1547 print_rtl_with_bb (FILE *outf
, rtx rtx_first
)
1552 fprintf (outf
, "(nil)\n");
1555 enum bb_state
{ NOT_IN_BB
, IN_ONE_BB
, IN_MULTIPLE_BB
};
1556 int max_uid
= get_max_uid ();
1557 basic_block
*start
= XCNEWVEC (basic_block
, max_uid
);
1558 basic_block
*end
= XCNEWVEC (basic_block
, max_uid
);
1559 enum bb_state
*in_bb_p
= XCNEWVEC (enum bb_state
, max_uid
);
1563 FOR_EACH_BB_REVERSE (bb
)
1567 start
[INSN_UID (BB_HEAD (bb
))] = bb
;
1568 end
[INSN_UID (BB_END (bb
))] = bb
;
1569 for (x
= BB_HEAD (bb
); x
!= NULL_RTX
; x
= NEXT_INSN (x
))
1571 enum bb_state state
= IN_MULTIPLE_BB
;
1573 if (in_bb_p
[INSN_UID (x
)] == NOT_IN_BB
)
1575 in_bb_p
[INSN_UID (x
)] = state
;
1577 if (x
== BB_END (bb
))
1582 for (tmp_rtx
= rtx_first
; NULL
!= tmp_rtx
; tmp_rtx
= NEXT_INSN (tmp_rtx
))
1588 if ((bb
= start
[INSN_UID (tmp_rtx
)]) != NULL
)
1590 fprintf (outf
, ";; Start of basic block %d, registers live:",
1592 dump_regset (bb
->il
.rtl
->global_live_at_start
, outf
);
1594 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1596 fputs (";; Pred edge ", outf
);
1597 dump_edge_info (outf
, e
, 0);
1602 if (in_bb_p
[INSN_UID (tmp_rtx
)] == NOT_IN_BB
1603 && !NOTE_P (tmp_rtx
)
1604 && !BARRIER_P (tmp_rtx
))
1605 fprintf (outf
, ";; Insn is not within a basic block\n");
1606 else if (in_bb_p
[INSN_UID (tmp_rtx
)] == IN_MULTIPLE_BB
)
1607 fprintf (outf
, ";; Insn is in multiple basic blocks\n");
1609 did_output
= print_rtl_single (outf
, tmp_rtx
);
1611 if ((bb
= end
[INSN_UID (tmp_rtx
)]) != NULL
)
1613 fprintf (outf
, ";; End of basic block %d, registers live:",
1615 dump_regset (bb
->il
.rtl
->global_live_at_end
, outf
);
1617 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1619 fputs (";; Succ edge ", outf
);
1620 dump_edge_info (outf
, e
, 1);
1634 if (current_function_epilogue_delay_list
!= 0)
1636 fprintf (outf
, "\n;; Insns in epilogue delay list:\n\n");
1637 for (tmp_rtx
= current_function_epilogue_delay_list
; tmp_rtx
!= 0;
1638 tmp_rtx
= XEXP (tmp_rtx
, 1))
1639 print_rtl_single (outf
, XEXP (tmp_rtx
, 0));
1644 update_br_prob_note (basic_block bb
)
1647 if (!JUMP_P (BB_END (bb
)))
1649 note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
);
1650 if (!note
|| INTVAL (XEXP (note
, 0)) == BRANCH_EDGE (bb
)->probability
)
1652 XEXP (note
, 0) = GEN_INT (BRANCH_EDGE (bb
)->probability
);
1655 /* Get the last insn associated with block BB (that includes barriers and
1656 tablejumps after BB). */
1658 get_last_bb_insn (basic_block bb
)
1661 rtx end
= BB_END (bb
);
1663 /* Include any jump table following the basic block. */
1664 if (tablejump_p (end
, NULL
, &tmp
))
1667 /* Include any barriers that may follow the basic block. */
1668 tmp
= next_nonnote_insn (end
);
1669 while (tmp
&& BARRIER_P (tmp
))
1672 tmp
= next_nonnote_insn (end
);
1678 /* Verify the CFG and RTL consistency common for both underlying RTL and
1681 Currently it does following checks:
1683 - test head/end pointers
1684 - overlapping of basic blocks
1685 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1686 - tails of basic blocks (ensure that boundary is necessary)
1687 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1688 and NOTE_INSN_BASIC_BLOCK
1689 - verify that no fall_thru edge crosses hot/cold partition boundaries
1691 In future it can be extended check a lot of other stuff as well
1692 (reachability of basic blocks, life information, etc. etc.). */
1695 rtl_verify_flow_info_1 (void)
1697 const int max_uid
= get_max_uid ();
1698 rtx last_head
= get_last_insn ();
1699 basic_block
*bb_info
;
1704 bb_info
= XCNEWVEC (basic_block
, max_uid
);
1706 FOR_EACH_BB_REVERSE (bb
)
1708 rtx head
= BB_HEAD (bb
);
1709 rtx end
= BB_END (bb
);
1711 /* Verify the end of the basic block is in the INSN chain. */
1712 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1716 if (!(bb
->flags
& BB_RTL
))
1718 error ("BB_RTL flag not set for block %d", bb
->index
);
1724 error ("end insn %d for block %d not found in the insn stream",
1725 INSN_UID (end
), bb
->index
);
1729 /* Work backwards from the end to the head of the basic block
1730 to verify the head is in the RTL chain. */
1731 for (; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1733 /* While walking over the insn chain, verify insns appear
1734 in only one basic block and initialize the BB_INFO array
1735 used by other passes. */
1736 if (bb_info
[INSN_UID (x
)] != NULL
)
1738 error ("insn %d is in multiple basic blocks (%d and %d)",
1739 INSN_UID (x
), bb
->index
, bb_info
[INSN_UID (x
)]->index
);
1743 bb_info
[INSN_UID (x
)] = bb
;
1750 error ("head insn %d for block %d not found in the insn stream",
1751 INSN_UID (head
), bb
->index
);
1758 /* Now check the basic blocks (boundaries etc.) */
1759 FOR_EACH_BB_REVERSE (bb
)
1761 int n_fallthru
= 0, n_eh
= 0, n_call
= 0, n_abnormal
= 0, n_branch
= 0;
1762 edge e
, fallthru
= NULL
;
1766 if (JUMP_P (BB_END (bb
))
1767 && (note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
))
1768 && EDGE_COUNT (bb
->succs
) >= 2
1769 && any_condjump_p (BB_END (bb
)))
1771 if (INTVAL (XEXP (note
, 0)) != BRANCH_EDGE (bb
)->probability
1772 && profile_status
!= PROFILE_ABSENT
)
1774 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1775 INTVAL (XEXP (note
, 0)), BRANCH_EDGE (bb
)->probability
);
1779 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1781 if (e
->flags
& EDGE_FALLTHRU
)
1783 n_fallthru
++, fallthru
= e
;
1784 if ((e
->flags
& EDGE_CROSSING
)
1785 || (BB_PARTITION (e
->src
) != BB_PARTITION (e
->dest
)
1786 && e
->src
!= ENTRY_BLOCK_PTR
1787 && e
->dest
!= EXIT_BLOCK_PTR
))
1789 error ("fallthru edge crosses section boundary (bb %i)",
1795 if ((e
->flags
& ~(EDGE_DFS_BACK
1797 | EDGE_IRREDUCIBLE_LOOP
1799 | EDGE_CROSSING
)) == 0)
1802 if (e
->flags
& EDGE_ABNORMAL_CALL
)
1805 if (e
->flags
& EDGE_EH
)
1807 else if (e
->flags
& EDGE_ABNORMAL
)
1811 if (n_eh
&& GET_CODE (PATTERN (BB_END (bb
))) != RESX
1812 && !find_reg_note (BB_END (bb
), REG_EH_REGION
, NULL_RTX
))
1814 error ("missing REG_EH_REGION note in the end of bb %i", bb
->index
);
1818 && (!JUMP_P (BB_END (bb
))
1819 || (n_branch
> 1 && (any_uncondjump_p (BB_END (bb
))
1820 || any_condjump_p (BB_END (bb
))))))
1822 error ("too many outgoing branch edges from bb %i", bb
->index
);
1825 if (n_fallthru
&& any_uncondjump_p (BB_END (bb
)))
1827 error ("fallthru edge after unconditional jump %i", bb
->index
);
1830 if (n_branch
!= 1 && any_uncondjump_p (BB_END (bb
)))
1832 error ("wrong amount of branch edges after unconditional jump %i", bb
->index
);
1835 if (n_branch
!= 1 && any_condjump_p (BB_END (bb
))
1836 && JUMP_LABEL (BB_END (bb
)) != BB_HEAD (fallthru
->dest
))
1838 error ("wrong amount of branch edges after conditional jump %i",
1842 if (n_call
&& !CALL_P (BB_END (bb
)))
1844 error ("call edges for non-call insn in bb %i", bb
->index
);
1848 && (!CALL_P (BB_END (bb
)) && n_call
!= n_abnormal
)
1849 && (!JUMP_P (BB_END (bb
))
1850 || any_condjump_p (BB_END (bb
))
1851 || any_uncondjump_p (BB_END (bb
))))
1853 error ("abnormal edges for no purpose in bb %i", bb
->index
);
1857 for (x
= BB_HEAD (bb
); x
!= NEXT_INSN (BB_END (bb
)); x
= NEXT_INSN (x
))
1858 /* We may have a barrier inside a basic block before dead code
1859 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1860 if (!BARRIER_P (x
) && BLOCK_FOR_INSN (x
) != bb
)
1863 if (! BLOCK_FOR_INSN (x
))
1865 ("insn %d inside basic block %d but block_for_insn is NULL",
1866 INSN_UID (x
), bb
->index
);
1869 ("insn %d inside basic block %d but block_for_insn is %i",
1870 INSN_UID (x
), bb
->index
, BLOCK_FOR_INSN (x
)->index
);
1875 /* OK pointers are correct. Now check the header of basic
1876 block. It ought to contain optional CODE_LABEL followed
1877 by NOTE_BASIC_BLOCK. */
1881 if (BB_END (bb
) == x
)
1883 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1891 if (!NOTE_INSN_BASIC_BLOCK_P (x
) || NOTE_BASIC_BLOCK (x
) != bb
)
1893 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1898 if (BB_END (bb
) == x
)
1899 /* Do checks for empty blocks here. */
1902 for (x
= NEXT_INSN (x
); x
; x
= NEXT_INSN (x
))
1904 if (NOTE_INSN_BASIC_BLOCK_P (x
))
1906 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1907 INSN_UID (x
), bb
->index
);
1911 if (x
== BB_END (bb
))
1914 if (control_flow_insn_p (x
))
1916 error ("in basic block %d:", bb
->index
);
1917 fatal_insn ("flow control insn inside a basic block", x
);
1927 /* Verify the CFG and RTL consistency common for both underlying RTL and
1930 Currently it does following checks:
1931 - all checks of rtl_verify_flow_info_1
1932 - check that all insns are in the basic blocks
1933 (except the switch handling code, barriers and notes)
1934 - check that all returns are followed by barriers
1935 - check that all fallthru edge points to the adjacent blocks. */
1937 rtl_verify_flow_info (void)
1940 int err
= rtl_verify_flow_info_1 ();
1943 const rtx rtx_first
= get_insns ();
1944 basic_block last_bb_seen
= ENTRY_BLOCK_PTR
, curr_bb
= NULL
;
1946 FOR_EACH_BB_REVERSE (bb
)
1951 if (bb
->predictions
)
1953 error ("bb prediction set for block %i, but it is not used in RTL land", bb
->index
);
1957 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1958 if (e
->flags
& EDGE_FALLTHRU
)
1964 /* Ensure existence of barrier in BB with no fallthru edges. */
1965 for (insn
= BB_END (bb
); !insn
|| !BARRIER_P (insn
);
1966 insn
= NEXT_INSN (insn
))
1969 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BASIC_BLOCK
))
1971 error ("missing barrier after block %i", bb
->index
);
1976 else if (e
->src
!= ENTRY_BLOCK_PTR
1977 && e
->dest
!= EXIT_BLOCK_PTR
)
1981 if (e
->src
->next_bb
!= e
->dest
)
1984 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
1985 e
->src
->index
, e
->dest
->index
);
1989 for (insn
= NEXT_INSN (BB_END (e
->src
)); insn
!= BB_HEAD (e
->dest
);
1990 insn
= NEXT_INSN (insn
))
1991 if (BARRIER_P (insn
) || INSN_P (insn
))
1993 error ("verify_flow_info: Incorrect fallthru %i->%i",
1994 e
->src
->index
, e
->dest
->index
);
1995 fatal_insn ("wrong insn in the fallthru edge", insn
);
2002 last_bb_seen
= ENTRY_BLOCK_PTR
;
2004 for (x
= rtx_first
; x
; x
= NEXT_INSN (x
))
2006 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2008 bb
= NOTE_BASIC_BLOCK (x
);
2011 if (bb
!= last_bb_seen
->next_bb
)
2012 internal_error ("basic blocks not laid down consecutively");
2014 curr_bb
= last_bb_seen
= bb
;
2019 switch (GET_CODE (x
))
2026 /* An addr_vec is placed outside any basic block. */
2028 && JUMP_P (NEXT_INSN (x
))
2029 && (GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_DIFF_VEC
2030 || GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_VEC
))
2033 /* But in any case, non-deletable labels can appear anywhere. */
2037 fatal_insn ("insn outside basic block", x
);
2042 && returnjump_p (x
) && ! condjump_p (x
)
2043 && ! (NEXT_INSN (x
) && BARRIER_P (NEXT_INSN (x
))))
2044 fatal_insn ("return not followed by barrier", x
);
2045 if (curr_bb
&& x
== BB_END (curr_bb
))
2049 if (num_bb_notes
!= n_basic_blocks
- NUM_FIXED_BLOCKS
)
2051 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2052 num_bb_notes
, n_basic_blocks
);
2057 /* Assume that the preceding pass has possibly eliminated jump instructions
2058 or converted the unconditional jumps. Eliminate the edges from CFG.
2059 Return true if any edges are eliminated. */
2062 purge_dead_edges (basic_block bb
)
2065 rtx insn
= BB_END (bb
), note
;
2066 bool purged
= false;
2070 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2071 if (NONJUMP_INSN_P (insn
)
2072 && (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
)))
2076 if (! may_trap_p (PATTERN (insn
))
2077 || ((eqnote
= find_reg_equal_equiv_note (insn
))
2078 && ! may_trap_p (XEXP (eqnote
, 0))))
2079 remove_note (insn
, note
);
2082 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2083 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2085 /* There are three types of edges we need to handle correctly here: EH
2086 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2087 latter can appear when nonlocal gotos are used. */
2088 if (e
->flags
& EDGE_EH
)
2090 if (can_throw_internal (BB_END (bb
))
2091 /* If this is a call edge, verify that this is a call insn. */
2092 && (! (e
->flags
& EDGE_ABNORMAL_CALL
)
2093 || CALL_P (BB_END (bb
))))
2099 else if (e
->flags
& EDGE_ABNORMAL_CALL
)
2101 if (CALL_P (BB_END (bb
))
2102 && (! (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
))
2103 || INTVAL (XEXP (note
, 0)) >= 0))
2116 bb
->flags
|= BB_DIRTY
;
2126 /* We do care only about conditional jumps and simplejumps. */
2127 if (!any_condjump_p (insn
)
2128 && !returnjump_p (insn
)
2129 && !simplejump_p (insn
))
2132 /* Branch probability/prediction notes are defined only for
2133 condjumps. We've possibly turned condjump into simplejump. */
2134 if (simplejump_p (insn
))
2136 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2138 remove_note (insn
, note
);
2139 while ((note
= find_reg_note (insn
, REG_BR_PRED
, NULL
)))
2140 remove_note (insn
, note
);
2143 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2145 /* Avoid abnormal flags to leak from computed jumps turned
2146 into simplejumps. */
2148 e
->flags
&= ~EDGE_ABNORMAL
;
2150 /* See if this edge is one we should keep. */
2151 if ((e
->flags
& EDGE_FALLTHRU
) && any_condjump_p (insn
))
2152 /* A conditional jump can fall through into the next
2153 block, so we should keep the edge. */
2158 else if (e
->dest
!= EXIT_BLOCK_PTR
2159 && BB_HEAD (e
->dest
) == JUMP_LABEL (insn
))
2160 /* If the destination block is the target of the jump,
2166 else if (e
->dest
== EXIT_BLOCK_PTR
&& returnjump_p (insn
))
2167 /* If the destination block is the exit block, and this
2168 instruction is a return, then keep the edge. */
2173 else if ((e
->flags
& EDGE_EH
) && can_throw_internal (insn
))
2174 /* Keep the edges that correspond to exceptions thrown by
2175 this instruction and rematerialize the EDGE_ABNORMAL
2176 flag we just cleared above. */
2178 e
->flags
|= EDGE_ABNORMAL
;
2183 /* We do not need this edge. */
2184 bb
->flags
|= BB_DIRTY
;
2189 if (EDGE_COUNT (bb
->succs
) == 0 || !purged
)
2193 fprintf (dump_file
, "Purged edges from bb %i\n", bb
->index
);
2198 /* Redistribute probabilities. */
2199 if (single_succ_p (bb
))
2201 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2202 single_succ_edge (bb
)->count
= bb
->count
;
2206 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2210 b
= BRANCH_EDGE (bb
);
2211 f
= FALLTHRU_EDGE (bb
);
2212 b
->probability
= INTVAL (XEXP (note
, 0));
2213 f
->probability
= REG_BR_PROB_BASE
- b
->probability
;
2214 b
->count
= bb
->count
* b
->probability
/ REG_BR_PROB_BASE
;
2215 f
->count
= bb
->count
* f
->probability
/ REG_BR_PROB_BASE
;
2220 else if (CALL_P (insn
) && SIBLING_CALL_P (insn
))
2222 /* First, there should not be any EH or ABCALL edges resulting
2223 from non-local gotos and the like. If there were, we shouldn't
2224 have created the sibcall in the first place. Second, there
2225 should of course never have been a fallthru edge. */
2226 gcc_assert (single_succ_p (bb
));
2227 gcc_assert (single_succ_edge (bb
)->flags
2228 == (EDGE_SIBCALL
| EDGE_ABNORMAL
));
2233 /* If we don't see a jump insn, we don't know exactly why the block would
2234 have been broken at this point. Look for a simple, non-fallthru edge,
2235 as these are only created by conditional branches. If we find such an
2236 edge we know that there used to be a jump here and can then safely
2237 remove all non-fallthru edges. */
2239 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2240 if (! (e
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
)))
2249 /* Remove all but the fake and fallthru edges. The fake edge may be
2250 the only successor for this block in the case of noreturn
2252 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2254 if (!(e
->flags
& (EDGE_FALLTHRU
| EDGE_FAKE
)))
2256 bb
->flags
|= BB_DIRTY
;
2264 gcc_assert (single_succ_p (bb
));
2266 single_succ_edge (bb
)->probability
= REG_BR_PROB_BASE
;
2267 single_succ_edge (bb
)->count
= bb
->count
;
2270 fprintf (dump_file
, "Purged non-fallthru edges from bb %i\n",
2275 /* Search all basic blocks for potentially dead edges and purge them. Return
2276 true if some edge has been eliminated. */
2279 purge_all_dead_edges (void)
2286 bool purged_here
= purge_dead_edges (bb
);
2288 purged
|= purged_here
;
2294 /* Same as split_block but update cfg_layout structures. */
2297 cfg_layout_split_block (basic_block bb
, void *insnp
)
2300 basic_block new_bb
= rtl_split_block (bb
, insn
);
2302 new_bb
->il
.rtl
->footer
= bb
->il
.rtl
->footer
;
2303 bb
->il
.rtl
->footer
= NULL
;
2309 /* Redirect Edge to DEST. */
2311 cfg_layout_redirect_edge_and_branch (edge e
, basic_block dest
)
2313 basic_block src
= e
->src
;
2316 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
2319 if (e
->dest
== dest
)
2322 if (e
->src
!= ENTRY_BLOCK_PTR
2323 && (ret
= try_redirect_by_replacing_jump (e
, dest
, true)))
2325 src
->flags
|= BB_DIRTY
;
2329 if (e
->src
== ENTRY_BLOCK_PTR
2330 && (e
->flags
& EDGE_FALLTHRU
) && !(e
->flags
& EDGE_COMPLEX
))
2333 fprintf (dump_file
, "Redirecting entry edge from bb %i to %i\n",
2334 e
->src
->index
, dest
->index
);
2336 e
->src
->flags
|= BB_DIRTY
;
2337 redirect_edge_succ (e
, dest
);
2341 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2342 in the case the basic block appears to be in sequence. Avoid this
2345 if (e
->flags
& EDGE_FALLTHRU
)
2347 /* Redirect any branch edges unified with the fallthru one. */
2348 if (JUMP_P (BB_END (src
))
2349 && label_is_jump_target_p (BB_HEAD (e
->dest
),
2355 fprintf (dump_file
, "Fallthru edge unified with branch "
2356 "%i->%i redirected to %i\n",
2357 e
->src
->index
, e
->dest
->index
, dest
->index
);
2358 e
->flags
&= ~EDGE_FALLTHRU
;
2359 redirected
= redirect_branch_edge (e
, dest
);
2360 gcc_assert (redirected
);
2361 e
->flags
|= EDGE_FALLTHRU
;
2362 e
->src
->flags
|= BB_DIRTY
;
2365 /* In case we are redirecting fallthru edge to the branch edge
2366 of conditional jump, remove it. */
2367 if (EDGE_COUNT (src
->succs
) == 2)
2369 /* Find the edge that is different from E. */
2370 edge s
= EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
);
2373 && any_condjump_p (BB_END (src
))
2374 && onlyjump_p (BB_END (src
)))
2375 delete_insn (BB_END (src
));
2377 ret
= redirect_edge_succ_nodup (e
, dest
);
2379 fprintf (dump_file
, "Fallthru edge %i->%i redirected to %i\n",
2380 e
->src
->index
, e
->dest
->index
, dest
->index
);
2383 ret
= redirect_branch_edge (e
, dest
);
2385 /* We don't want simplejumps in the insn stream during cfglayout. */
2386 gcc_assert (!simplejump_p (BB_END (src
)));
2388 src
->flags
|= BB_DIRTY
;
2392 /* Simple wrapper as we always can redirect fallthru edges. */
2394 cfg_layout_redirect_edge_and_branch_force (edge e
, basic_block dest
)
2396 edge redirected
= cfg_layout_redirect_edge_and_branch (e
, dest
);
2398 gcc_assert (redirected
);
2402 /* Same as delete_basic_block but update cfg_layout structures. */
2405 cfg_layout_delete_block (basic_block bb
)
2407 rtx insn
, next
, prev
= PREV_INSN (BB_HEAD (bb
)), *to
, remaints
;
2409 if (bb
->il
.rtl
->header
)
2411 next
= BB_HEAD (bb
);
2413 NEXT_INSN (prev
) = bb
->il
.rtl
->header
;
2415 set_first_insn (bb
->il
.rtl
->header
);
2416 PREV_INSN (bb
->il
.rtl
->header
) = prev
;
2417 insn
= bb
->il
.rtl
->header
;
2418 while (NEXT_INSN (insn
))
2419 insn
= NEXT_INSN (insn
);
2420 NEXT_INSN (insn
) = next
;
2421 PREV_INSN (next
) = insn
;
2423 next
= NEXT_INSN (BB_END (bb
));
2424 if (bb
->il
.rtl
->footer
)
2426 insn
= bb
->il
.rtl
->footer
;
2429 if (BARRIER_P (insn
))
2431 if (PREV_INSN (insn
))
2432 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
2434 bb
->il
.rtl
->footer
= NEXT_INSN (insn
);
2435 if (NEXT_INSN (insn
))
2436 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
2440 insn
= NEXT_INSN (insn
);
2442 if (bb
->il
.rtl
->footer
)
2445 NEXT_INSN (insn
) = bb
->il
.rtl
->footer
;
2446 PREV_INSN (bb
->il
.rtl
->footer
) = insn
;
2447 while (NEXT_INSN (insn
))
2448 insn
= NEXT_INSN (insn
);
2449 NEXT_INSN (insn
) = next
;
2451 PREV_INSN (next
) = insn
;
2453 set_last_insn (insn
);
2456 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2457 to
= &bb
->next_bb
->il
.rtl
->header
;
2459 to
= &cfg_layout_function_footer
;
2461 rtl_delete_block (bb
);
2464 prev
= NEXT_INSN (prev
);
2466 prev
= get_insns ();
2468 next
= PREV_INSN (next
);
2470 next
= get_last_insn ();
2472 if (next
&& NEXT_INSN (next
) != prev
)
2474 remaints
= unlink_insn_chain (prev
, next
);
2476 while (NEXT_INSN (insn
))
2477 insn
= NEXT_INSN (insn
);
2478 NEXT_INSN (insn
) = *to
;
2480 PREV_INSN (*to
) = insn
;
2485 /* Return true when blocks A and B can be safely merged. */
2487 cfg_layout_can_merge_blocks_p (basic_block a
, basic_block b
)
2489 /* If we are partitioning hot/cold basic blocks, we don't want to
2490 mess up unconditional or indirect jumps that cross between hot
2493 Basic block partitioning may result in some jumps that appear to
2494 be optimizable (or blocks that appear to be mergeable), but which really
2495 must be left untouched (they are required to make it safely across
2496 partition boundaries). See the comments at the top of
2497 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2499 if (BB_PARTITION (a
) != BB_PARTITION (b
))
2502 /* There must be exactly one edge in between the blocks. */
2503 return (single_succ_p (a
)
2504 && single_succ (a
) == b
2505 && single_pred_p (b
) == 1
2507 /* Must be simple edge. */
2508 && !(single_succ_edge (a
)->flags
& EDGE_COMPLEX
)
2509 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
2510 /* If the jump insn has side effects,
2511 we can't kill the edge. */
2512 && (!JUMP_P (BB_END (a
))
2513 || (reload_completed
2514 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
2517 /* Merge block A and B. The blocks must be mergeable. */
2520 cfg_layout_merge_blocks (basic_block a
, basic_block b
)
2522 #ifdef ENABLE_CHECKING
2523 gcc_assert (cfg_layout_can_merge_blocks_p (a
, b
));
2526 /* If there was a CODE_LABEL beginning B, delete it. */
2527 if (LABEL_P (BB_HEAD (b
)))
2529 /* This might have been an EH label that no longer has incoming
2530 EH edges. Update data structures to match. */
2531 maybe_remove_eh_handler (BB_HEAD (b
));
2533 delete_insn (BB_HEAD (b
));
2536 /* We should have fallthru edge in a, or we can do dummy redirection to get
2538 if (JUMP_P (BB_END (a
)))
2539 try_redirect_by_replacing_jump (EDGE_SUCC (a
, 0), b
, true);
2540 gcc_assert (!JUMP_P (BB_END (a
)));
2542 /* Possible line number notes should appear in between. */
2543 if (b
->il
.rtl
->header
)
2545 rtx first
= BB_END (a
), last
;
2547 last
= emit_insn_after_noloc (b
->il
.rtl
->header
, BB_END (a
));
2548 delete_insn_chain (NEXT_INSN (first
), last
);
2549 b
->il
.rtl
->header
= NULL
;
2552 /* In the case basic blocks are not adjacent, move them around. */
2553 if (NEXT_INSN (BB_END (a
)) != BB_HEAD (b
))
2555 rtx first
= unlink_insn_chain (BB_HEAD (b
), BB_END (b
));
2557 emit_insn_after_noloc (first
, BB_END (a
));
2558 /* Skip possible DELETED_LABEL insn. */
2559 if (!NOTE_INSN_BASIC_BLOCK_P (first
))
2560 first
= NEXT_INSN (first
);
2561 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first
));
2563 delete_insn (first
);
2565 /* Otherwise just re-associate the instructions. */
2570 for (insn
= BB_HEAD (b
);
2571 insn
!= NEXT_INSN (BB_END (b
));
2572 insn
= NEXT_INSN (insn
))
2573 set_block_for_insn (insn
, a
);
2575 /* Skip possible DELETED_LABEL insn. */
2576 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
2577 insn
= NEXT_INSN (insn
);
2578 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
2580 BB_END (a
) = BB_END (b
);
2584 /* Possible tablejumps and barriers should appear after the block. */
2585 if (b
->il
.rtl
->footer
)
2587 if (!a
->il
.rtl
->footer
)
2588 a
->il
.rtl
->footer
= b
->il
.rtl
->footer
;
2591 rtx last
= a
->il
.rtl
->footer
;
2593 while (NEXT_INSN (last
))
2594 last
= NEXT_INSN (last
);
2595 NEXT_INSN (last
) = b
->il
.rtl
->footer
;
2596 PREV_INSN (b
->il
.rtl
->footer
) = last
;
2598 b
->il
.rtl
->footer
= NULL
;
2600 a
->il
.rtl
->global_live_at_end
= b
->il
.rtl
->global_live_at_end
;
2603 fprintf (dump_file
, "Merged blocks %d and %d.\n",
2604 a
->index
, b
->index
);
2610 cfg_layout_split_edge (edge e
)
2612 basic_block new_bb
=
2613 create_basic_block (e
->src
!= ENTRY_BLOCK_PTR
2614 ? NEXT_INSN (BB_END (e
->src
)) : get_insns (),
2617 /* ??? This info is likely going to be out of date very soon, but we must
2618 create it to avoid getting an ICE later. */
2619 if (e
->dest
->il
.rtl
->global_live_at_start
)
2621 new_bb
->il
.rtl
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
2622 new_bb
->il
.rtl
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
2623 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_start
,
2624 e
->dest
->il
.rtl
->global_live_at_start
);
2625 COPY_REG_SET (new_bb
->il
.rtl
->global_live_at_end
,
2626 e
->dest
->il
.rtl
->global_live_at_start
);
2629 make_edge (new_bb
, e
->dest
, EDGE_FALLTHRU
);
2630 redirect_edge_and_branch_force (e
, new_bb
);
2635 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2638 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED
)
2642 /* Return 1 if BB ends with a call, possibly followed by some
2643 instructions that must stay with the call, 0 otherwise. */
2646 rtl_block_ends_with_call_p (basic_block bb
)
2648 rtx insn
= BB_END (bb
);
2650 while (!CALL_P (insn
)
2651 && insn
!= BB_HEAD (bb
)
2652 && keep_with_call_p (insn
))
2653 insn
= PREV_INSN (insn
);
2654 return (CALL_P (insn
));
2657 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2660 rtl_block_ends_with_condjump_p (basic_block bb
)
2662 return any_condjump_p (BB_END (bb
));
2665 /* Return true if we need to add fake edge to exit.
2666 Helper function for rtl_flow_call_edges_add. */
2669 need_fake_edge_p (rtx insn
)
2675 && !SIBLING_CALL_P (insn
)
2676 && !find_reg_note (insn
, REG_NORETURN
, NULL
)
2677 && !CONST_OR_PURE_CALL_P (insn
)))
2680 return ((GET_CODE (PATTERN (insn
)) == ASM_OPERANDS
2681 && MEM_VOLATILE_P (PATTERN (insn
)))
2682 || (GET_CODE (PATTERN (insn
)) == PARALLEL
2683 && asm_noperands (insn
) != -1
2684 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn
), 0, 0)))
2685 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
);
2688 /* Add fake edges to the function exit for any non constant and non noreturn
2689 calls, volatile inline assembly in the bitmap of blocks specified by
2690 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2693 The goal is to expose cases in which entering a basic block does not imply
2694 that all subsequent instructions must be executed. */
2697 rtl_flow_call_edges_add (sbitmap blocks
)
2700 int blocks_split
= 0;
2701 int last_bb
= last_basic_block
;
2702 bool check_last_block
= false;
2704 if (n_basic_blocks
== NUM_FIXED_BLOCKS
)
2708 check_last_block
= true;
2710 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
2712 /* In the last basic block, before epilogue generation, there will be
2713 a fallthru edge to EXIT. Special care is required if the last insn
2714 of the last basic block is a call because make_edge folds duplicate
2715 edges, which would result in the fallthru edge also being marked
2716 fake, which would result in the fallthru edge being removed by
2717 remove_fake_edges, which would result in an invalid CFG.
2719 Moreover, we can't elide the outgoing fake edge, since the block
2720 profiler needs to take this into account in order to solve the minimal
2721 spanning tree in the case that the call doesn't return.
2723 Handle this by adding a dummy instruction in a new last basic block. */
2724 if (check_last_block
)
2726 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
2727 rtx insn
= BB_END (bb
);
2729 /* Back up past insns that must be kept in the same block as a call. */
2730 while (insn
!= BB_HEAD (bb
)
2731 && keep_with_call_p (insn
))
2732 insn
= PREV_INSN (insn
);
2734 if (need_fake_edge_p (insn
))
2738 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
2741 insert_insn_on_edge (gen_rtx_USE (VOIDmode
, const0_rtx
), e
);
2742 commit_edge_insertions ();
2747 /* Now add fake edges to the function exit for any non constant
2748 calls since there is no way that we can determine if they will
2751 for (i
= NUM_FIXED_BLOCKS
; i
< last_bb
; i
++)
2753 basic_block bb
= BASIC_BLOCK (i
);
2760 if (blocks
&& !TEST_BIT (blocks
, i
))
2763 for (insn
= BB_END (bb
); ; insn
= prev_insn
)
2765 prev_insn
= PREV_INSN (insn
);
2766 if (need_fake_edge_p (insn
))
2769 rtx split_at_insn
= insn
;
2771 /* Don't split the block between a call and an insn that should
2772 remain in the same block as the call. */
2774 while (split_at_insn
!= BB_END (bb
)
2775 && keep_with_call_p (NEXT_INSN (split_at_insn
)))
2776 split_at_insn
= NEXT_INSN (split_at_insn
);
2778 /* The handling above of the final block before the epilogue
2779 should be enough to verify that there is no edge to the exit
2780 block in CFG already. Calling make_edge in such case would
2781 cause us to mark that edge as fake and remove it later. */
2783 #ifdef ENABLE_CHECKING
2784 if (split_at_insn
== BB_END (bb
))
2786 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
2787 gcc_assert (e
== NULL
);
2791 /* Note that the following may create a new basic block
2792 and renumber the existing basic blocks. */
2793 if (split_at_insn
!= BB_END (bb
))
2795 e
= split_block (bb
, split_at_insn
);
2800 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
2803 if (insn
== BB_HEAD (bb
))
2809 verify_flow_info ();
2811 return blocks_split
;
2814 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2815 the conditional branch target, SECOND_HEAD should be the fall-thru
2816 there is no need to handle this here the loop versioning code handles
2817 this. the reason for SECON_HEAD is that it is needed for condition
2818 in trees, and this should be of the same type since it is a hook. */
2820 rtl_lv_add_condition_to_bb (basic_block first_head
,
2821 basic_block second_head ATTRIBUTE_UNUSED
,
2822 basic_block cond_bb
, void *comp_rtx
)
2824 rtx label
, seq
, jump
;
2825 rtx op0
= XEXP ((rtx
)comp_rtx
, 0);
2826 rtx op1
= XEXP ((rtx
)comp_rtx
, 1);
2827 enum rtx_code comp
= GET_CODE ((rtx
)comp_rtx
);
2828 enum machine_mode mode
;
2831 label
= block_label (first_head
);
2832 mode
= GET_MODE (op0
);
2833 if (mode
== VOIDmode
)
2834 mode
= GET_MODE (op1
);
2837 op0
= force_operand (op0
, NULL_RTX
);
2838 op1
= force_operand (op1
, NULL_RTX
);
2839 do_compare_rtx_and_jump (op0
, op1
, comp
, 0,
2840 mode
, NULL_RTX
, NULL_RTX
, label
);
2841 jump
= get_last_insn ();
2842 JUMP_LABEL (jump
) = label
;
2843 LABEL_NUSES (label
)++;
2847 /* Add the new cond , in the new head. */
2848 emit_insn_after(seq
, BB_END(cond_bb
));
2852 /* Given a block B with unconditional branch at its end, get the
2853 store the return the branch edge and the fall-thru edge in
2854 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
2856 rtl_extract_cond_bb_edges (basic_block b
, edge
*branch_edge
,
2857 edge
*fallthru_edge
)
2859 edge e
= EDGE_SUCC (b
, 0);
2861 if (e
->flags
& EDGE_FALLTHRU
)
2864 *branch_edge
= EDGE_SUCC (b
, 1);
2869 *fallthru_edge
= EDGE_SUCC (b
, 1);
2874 init_rtl_bb_info (basic_block bb
)
2876 gcc_assert (!bb
->il
.rtl
);
2877 bb
->il
.rtl
= ggc_alloc_cleared (sizeof (struct rtl_bb_info
));
2881 /* Add EXPR to the end of basic block BB. */
2884 insert_insn_end_bb_new (rtx pat
, basic_block bb
)
2886 rtx insn
= BB_END (bb
);
2890 while (NEXT_INSN (pat_end
) != NULL_RTX
)
2891 pat_end
= NEXT_INSN (pat_end
);
2893 /* If the last insn is a jump, insert EXPR in front [taking care to
2894 handle cc0, etc. properly]. Similarly we need to care trapping
2895 instructions in presence of non-call exceptions. */
2898 || (NONJUMP_INSN_P (insn
)
2899 && (!single_succ_p (bb
)
2900 || single_succ_edge (bb
)->flags
& EDGE_ABNORMAL
)))
2905 /* If this is a jump table, then we can't insert stuff here. Since
2906 we know the previous real insn must be the tablejump, we insert
2907 the new instruction just before the tablejump. */
2908 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
2909 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
2910 insn
= prev_real_insn (insn
);
2913 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
2914 if cc0 isn't set. */
2915 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
2917 insn
= XEXP (note
, 0);
2920 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
2921 if (maybe_cc0_setter
2922 && INSN_P (maybe_cc0_setter
)
2923 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
2924 insn
= maybe_cc0_setter
;
2927 /* FIXME: What if something in cc0/jump uses value set in new
2929 new_insn
= emit_insn_before_noloc (pat
, insn
);
2932 /* Likewise if the last insn is a call, as will happen in the presence
2933 of exception handling. */
2934 else if (CALL_P (insn
)
2935 && (!single_succ_p (bb
)
2936 || single_succ_edge (bb
)->flags
& EDGE_ABNORMAL
))
2938 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
2939 we search backward and place the instructions before the first
2940 parameter is loaded. Do this for everyone for consistency and a
2941 presumption that we'll get better code elsewhere as well. */
2943 /* Since different machines initialize their parameter registers
2944 in different orders, assume nothing. Collect the set of all
2945 parameter registers. */
2946 insn
= find_first_parameter_load (insn
, BB_HEAD (bb
));
2948 /* If we found all the parameter loads, then we want to insert
2949 before the first parameter load.
2951 If we did not find all the parameter loads, then we might have
2952 stopped on the head of the block, which could be a CODE_LABEL.
2953 If we inserted before the CODE_LABEL, then we would be putting
2954 the insn in the wrong basic block. In that case, put the insn
2955 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
2956 while (LABEL_P (insn
)
2957 || NOTE_INSN_BASIC_BLOCK_P (insn
))
2958 insn
= NEXT_INSN (insn
);
2960 new_insn
= emit_insn_before_noloc (pat
, insn
);
2963 new_insn
= emit_insn_after_noloc (pat
, insn
);
2968 /* Implementation of CFG manipulation for linearized RTL. */
2969 struct cfg_hooks rtl_cfg_hooks
= {
2971 rtl_verify_flow_info
,
2973 rtl_create_basic_block
,
2974 rtl_redirect_edge_and_branch
,
2975 rtl_redirect_edge_and_branch_force
,
2978 rtl_move_block_after
,
2979 rtl_can_merge_blocks
, /* can_merge_blocks_p */
2983 NULL
, /* can_duplicate_block_p */
2984 NULL
, /* duplicate_block */
2986 rtl_make_forwarder_block
,
2987 rtl_tidy_fallthru_edge
,
2988 rtl_block_ends_with_call_p
,
2989 rtl_block_ends_with_condjump_p
,
2990 rtl_flow_call_edges_add
,
2991 NULL
, /* execute_on_growing_pred */
2992 NULL
, /* execute_on_shrinking_pred */
2993 NULL
, /* duplicate loop for trees */
2994 NULL
, /* lv_add_condition_to_bb */
2995 NULL
, /* lv_adjust_loop_header_phi*/
2996 NULL
, /* extract_cond_bb_edges */
2997 NULL
/* flush_pending_stmts */
3000 /* Implementation of CFG manipulation for cfg layout RTL, where
3001 basic block connected via fallthru edges does not have to be adjacent.
3002 This representation will hopefully become the default one in future
3003 version of the compiler. */
3005 /* We do not want to declare these functions in a header file, since they
3006 should only be used through the cfghooks interface, and we do not want to
3007 move them here since it would require also moving quite a lot of related
3009 extern bool cfg_layout_can_duplicate_bb_p (basic_block
);
3010 extern basic_block
cfg_layout_duplicate_bb (basic_block
);
3012 struct cfg_hooks cfg_layout_rtl_cfg_hooks
= {
3014 rtl_verify_flow_info_1
,
3016 cfg_layout_create_basic_block
,
3017 cfg_layout_redirect_edge_and_branch
,
3018 cfg_layout_redirect_edge_and_branch_force
,
3019 cfg_layout_delete_block
,
3020 cfg_layout_split_block
,
3021 rtl_move_block_after
,
3022 cfg_layout_can_merge_blocks_p
,
3023 cfg_layout_merge_blocks
,
3026 cfg_layout_can_duplicate_bb_p
,
3027 cfg_layout_duplicate_bb
,
3028 cfg_layout_split_edge
,
3029 rtl_make_forwarder_block
,
3031 rtl_block_ends_with_call_p
,
3032 rtl_block_ends_with_condjump_p
,
3033 rtl_flow_call_edges_add
,
3034 NULL
, /* execute_on_growing_pred */
3035 NULL
, /* execute_on_shrinking_pred */
3036 duplicate_loop_to_header_edge
, /* duplicate loop for trees */
3037 rtl_lv_add_condition_to_bb
, /* lv_add_condition_to_bb */
3038 NULL
, /* lv_adjust_loop_header_phi*/
3039 rtl_extract_cond_bb_edges
, /* extract_cond_bb_edges */
3040 NULL
/* flush_pending_stmts */