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 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains low level functions to manipulate the CFG and analyze it
23 that are aware of the RTL intermediate language.
25 Available functionality:
26 - Basic CFG/RTL manipulation API documented in cfghooks.h
27 - CFG-aware instruction chain manipulation
28 delete_insn, delete_insn_chain
29 - Edge splitting and committing to edges
30 insert_insn_on_edge, commit_edge_insertions
31 - CFG updating after insn simplification
32 purge_dead_edges, purge_all_dead_edges
34 Functions not supposed for generic use:
35 - Infrastructure to determine quickly basic block for insn
36 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
37 - Edge redirection with updating and optimizing of insn chain
38 block_label, tidy_fallthru_edge, force_nonfallthru */
42 #include "coretypes.h"
46 #include "hard-reg-set.h"
47 #include "basic-block.h"
56 #include "insn-config.h"
57 #include "cfglayout.h"
62 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
63 /* ??? Should probably be using LABEL_NUSES instead. It would take a
64 bit of surgery to be able to use or co-opt the routines in jump. */
67 static int can_delete_note_p (rtx
);
68 static int can_delete_label_p (rtx
);
69 static void commit_one_edge_insertion (edge
, int);
70 static rtx
last_loop_beg_note (rtx
);
71 static bool back_edge_of_syntactic_loop_p (basic_block
, basic_block
);
72 static basic_block
rtl_split_edge (edge
);
73 static bool rtl_move_block_after (basic_block
, basic_block
);
74 static int rtl_verify_flow_info (void);
75 static basic_block
cfg_layout_split_block (basic_block
, void *);
76 static edge
cfg_layout_redirect_edge_and_branch (edge
, basic_block
);
77 static basic_block
cfg_layout_redirect_edge_and_branch_force (edge
, basic_block
);
78 static void cfg_layout_delete_block (basic_block
);
79 static void rtl_delete_block (basic_block
);
80 static basic_block
rtl_redirect_edge_and_branch_force (edge
, basic_block
);
81 static edge
rtl_redirect_edge_and_branch (edge
, basic_block
);
82 static basic_block
rtl_split_block (basic_block
, void *);
83 static void rtl_dump_bb (basic_block
, FILE *, int);
84 static int rtl_verify_flow_info_1 (void);
85 static void mark_killed_regs (rtx
, rtx
, void *);
86 static void rtl_make_forwarder_block (edge
);
88 /* Return true if NOTE is not one of the ones that must be kept paired,
89 so that we may simply delete it. */
92 can_delete_note_p (rtx note
)
94 return (NOTE_LINE_NUMBER (note
) == NOTE_INSN_DELETED
95 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_BASIC_BLOCK
96 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_UNLIKELY_EXECUTED_CODE
);
99 /* True if a given label can be deleted. */
102 can_delete_label_p (rtx label
)
104 return (!LABEL_PRESERVE_P (label
)
105 /* User declared labels must be preserved. */
106 && LABEL_NAME (label
) == 0
107 && !in_expr_list_p (forced_labels
, label
)
108 && !in_expr_list_p (label_value_list
, label
));
111 /* Delete INSN by patching it out. Return the next insn. */
114 delete_insn (rtx insn
)
116 rtx next
= NEXT_INSN (insn
);
118 bool really_delete
= true;
122 /* Some labels can't be directly removed from the INSN chain, as they
123 might be references via variables, constant pool etc.
124 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
125 if (! can_delete_label_p (insn
))
127 const char *name
= LABEL_NAME (insn
);
129 really_delete
= false;
130 PUT_CODE (insn
, NOTE
);
131 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
132 NOTE_DELETED_LABEL_NAME (insn
) = name
;
135 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
140 /* If this insn has already been deleted, something is very wrong. */
141 gcc_assert (!INSN_DELETED_P (insn
));
143 INSN_DELETED_P (insn
) = 1;
146 /* If deleting a jump, decrement the use count of the label. Deleting
147 the label itself should happen in the normal course of block merging. */
150 && LABEL_P (JUMP_LABEL (insn
)))
151 LABEL_NUSES (JUMP_LABEL (insn
))--;
153 /* Also if deleting an insn that references a label. */
156 while ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)) != NULL_RTX
157 && LABEL_P (XEXP (note
, 0)))
159 LABEL_NUSES (XEXP (note
, 0))--;
160 remove_note (insn
, note
);
165 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
166 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
168 rtx pat
= PATTERN (insn
);
169 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
170 int len
= XVECLEN (pat
, diff_vec_p
);
173 for (i
= 0; i
< len
; i
++)
175 rtx label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
177 /* When deleting code in bulk (e.g. removing many unreachable
178 blocks) we can delete a label that's a target of the vector
179 before deleting the vector itself. */
181 LABEL_NUSES (label
)--;
188 /* Like delete_insn but also purge dead edges from BB. */
190 delete_insn_and_edges (rtx insn
)
196 && BLOCK_FOR_INSN (insn
)
197 && BB_END (BLOCK_FOR_INSN (insn
)) == insn
)
199 x
= delete_insn (insn
);
201 purge_dead_edges (BLOCK_FOR_INSN (insn
));
205 /* Unlink a chain of insns between START and FINISH, leaving notes
206 that must be paired. */
209 delete_insn_chain (rtx start
, rtx finish
)
213 /* Unchain the insns one by one. It would be quicker to delete all of these
214 with a single unchaining, rather than one at a time, but we need to keep
218 next
= NEXT_INSN (start
);
219 if (NOTE_P (start
) && !can_delete_note_p (start
))
222 next
= delete_insn (start
);
230 /* Like delete_insn but also purge dead edges from BB. */
232 delete_insn_chain_and_edges (rtx first
, rtx last
)
237 && BLOCK_FOR_INSN (last
)
238 && BB_END (BLOCK_FOR_INSN (last
)) == last
)
240 delete_insn_chain (first
, last
);
242 purge_dead_edges (BLOCK_FOR_INSN (last
));
245 /* Create a new basic block consisting of the instructions between HEAD and END
246 inclusive. This function is designed to allow fast BB construction - reuses
247 the note and basic block struct in BB_NOTE, if any and do not grow
248 BASIC_BLOCK chain and should be used directly only by CFG construction code.
249 END can be NULL in to create new empty basic block before HEAD. Both END
250 and HEAD can be NULL to create basic block at the end of INSN chain.
251 AFTER is the basic block we should be put after. */
254 create_basic_block_structure (rtx head
, rtx end
, rtx bb_note
, basic_block after
)
259 && (bb
= NOTE_BASIC_BLOCK (bb_note
)) != NULL
262 /* If we found an existing note, thread it back onto the chain. */
270 after
= PREV_INSN (head
);
274 if (after
!= bb_note
&& NEXT_INSN (after
) != bb_note
)
275 reorder_insns_nobb (bb_note
, bb_note
, after
);
279 /* Otherwise we must create a note and a basic block structure. */
285 = emit_note_after (NOTE_INSN_BASIC_BLOCK
, get_last_insn ());
286 else if (LABEL_P (head
) && end
)
288 bb_note
= emit_note_after (NOTE_INSN_BASIC_BLOCK
, head
);
294 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
, head
);
300 NOTE_BASIC_BLOCK (bb_note
) = bb
;
303 /* Always include the bb note in the block. */
304 if (NEXT_INSN (end
) == bb_note
)
309 bb
->index
= last_basic_block
++;
311 link_block (bb
, after
);
312 BASIC_BLOCK (bb
->index
) = bb
;
313 update_bb_for_insn (bb
);
314 BB_SET_PARTITION (bb
, BB_UNPARTITIONED
);
316 /* Tag the block so that we know it has been used when considering
317 other basic block notes. */
323 /* Create new basic block consisting of instructions in between HEAD and END
324 and place it to the BB chain after block AFTER. END can be NULL in to
325 create new empty basic block before HEAD. Both END and HEAD can be NULL to
326 create basic block at the end of INSN chain. */
329 rtl_create_basic_block (void *headp
, void *endp
, basic_block after
)
331 rtx head
= headp
, end
= endp
;
334 /* Grow the basic block array if needed. */
335 if ((size_t) last_basic_block
>= VARRAY_SIZE (basic_block_info
))
337 size_t new_size
= last_basic_block
+ (last_basic_block
+ 3) / 4;
338 VARRAY_GROW (basic_block_info
, new_size
);
343 bb
= create_basic_block_structure (head
, end
, NULL
, after
);
349 cfg_layout_create_basic_block (void *head
, void *end
, basic_block after
)
351 basic_block newbb
= rtl_create_basic_block (head
, end
, after
);
353 initialize_bb_rbi (newbb
);
357 /* Delete the insns in a (non-live) block. We physically delete every
358 non-deleted-note insn, and update the flow graph appropriately.
360 Return nonzero if we deleted an exception handler. */
362 /* ??? Preserving all such notes strikes me as wrong. It would be nice
363 to post-process the stream to remove empty blocks, loops, ranges, etc. */
366 rtl_delete_block (basic_block b
)
370 /* If the head of this block is a CODE_LABEL, then it might be the
371 label for an exception handler which can't be reached. We need
372 to remove the label from the exception_handler_label list. */
375 maybe_remove_eh_handler (insn
);
377 /* Include any jump table following the basic block. */
379 if (tablejump_p (end
, NULL
, &tmp
))
382 /* Include any barrier that may follow the basic block. */
383 tmp
= next_nonnote_insn (end
);
384 if (tmp
&& BARRIER_P (tmp
))
387 /* Selectively delete the entire chain. */
389 delete_insn_chain (insn
, end
);
392 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
395 compute_bb_for_insn (void)
401 rtx end
= BB_END (bb
);
404 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
406 BLOCK_FOR_INSN (insn
) = bb
;
413 /* Release the basic_block_for_insn array. */
416 free_bb_for_insn (void)
419 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
420 if (!BARRIER_P (insn
))
421 BLOCK_FOR_INSN (insn
) = NULL
;
424 /* Return RTX to emit after when we want to emit code on the entry of function. */
426 entry_of_function (void)
428 return (n_basic_blocks
? BB_HEAD (ENTRY_BLOCK_PTR
->next_bb
) : get_insns ());
431 /* Update insns block within BB. */
434 update_bb_for_insn (basic_block bb
)
438 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
440 if (!BARRIER_P (insn
))
441 set_block_for_insn (insn
, bb
);
442 if (insn
== BB_END (bb
))
447 /* Creates a new basic block just after basic block B by splitting
448 everything after specified instruction I. */
451 rtl_split_block (basic_block bb
, void *insnp
)
460 insn
= first_insn_after_basic_block_note (bb
);
463 insn
= PREV_INSN (insn
);
465 insn
= get_last_insn ();
468 /* We probably should check type of the insn so that we do not create
469 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
471 if (insn
== BB_END (bb
))
472 emit_note_after (NOTE_INSN_DELETED
, insn
);
474 /* Create the new basic block. */
475 new_bb
= create_basic_block (NEXT_INSN (insn
), BB_END (bb
), bb
);
476 BB_COPY_PARTITION (new_bb
, bb
);
479 /* Redirect the outgoing edges. */
480 new_bb
->succs
= bb
->succs
;
482 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
485 if (bb
->global_live_at_start
)
487 new_bb
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
488 new_bb
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
489 COPY_REG_SET (new_bb
->global_live_at_end
, bb
->global_live_at_end
);
491 /* We now have to calculate which registers are live at the end
492 of the split basic block and at the start of the new basic
493 block. Start with those registers that are known to be live
494 at the end of the original basic block and get
495 propagate_block to determine which registers are live. */
496 COPY_REG_SET (new_bb
->global_live_at_start
, bb
->global_live_at_end
);
497 propagate_block (new_bb
, new_bb
->global_live_at_start
, NULL
, NULL
, 0);
498 COPY_REG_SET (bb
->global_live_at_end
,
499 new_bb
->global_live_at_start
);
500 #ifdef HAVE_conditional_execution
501 /* In the presence of conditional execution we are not able to update
502 liveness precisely. */
503 if (reload_completed
)
505 bb
->flags
|= BB_DIRTY
;
506 new_bb
->flags
|= BB_DIRTY
;
514 /* Blocks A and B are to be merged into a single block A. The insns
515 are already contiguous. */
518 rtl_merge_blocks (basic_block a
, basic_block b
)
520 rtx b_head
= BB_HEAD (b
), b_end
= BB_END (b
), a_end
= BB_END (a
);
521 rtx del_first
= NULL_RTX
, del_last
= NULL_RTX
;
524 /* If there was a CODE_LABEL beginning B, delete it. */
525 if (LABEL_P (b_head
))
527 /* Detect basic blocks with nothing but a label. This can happen
528 in particular at the end of a function. */
532 del_first
= del_last
= b_head
;
533 b_head
= NEXT_INSN (b_head
);
536 /* Delete the basic block note and handle blocks containing just that
538 if (NOTE_INSN_BASIC_BLOCK_P (b_head
))
546 b_head
= NEXT_INSN (b_head
);
549 /* If there was a jump out of A, delete it. */
554 for (prev
= PREV_INSN (a_end
); ; prev
= PREV_INSN (prev
))
556 || NOTE_LINE_NUMBER (prev
) == NOTE_INSN_BASIC_BLOCK
557 || prev
== BB_HEAD (a
))
563 /* If this was a conditional jump, we need to also delete
564 the insn that set cc0. */
565 if (only_sets_cc0_p (prev
))
569 prev
= prev_nonnote_insn (prev
);
576 a_end
= PREV_INSN (del_first
);
578 else if (BARRIER_P (NEXT_INSN (a_end
)))
579 del_first
= NEXT_INSN (a_end
);
581 /* Delete everything marked above as well as crap that might be
582 hanging out between the two blocks. */
584 delete_insn_chain (del_first
, del_last
);
586 /* Reassociate the insns of B with A. */
591 for (x
= a_end
; x
!= b_end
; x
= NEXT_INSN (x
))
592 set_block_for_insn (x
, a
);
594 set_block_for_insn (b_end
, a
);
602 /* Return true when block A and B can be merged. */
604 rtl_can_merge_blocks (basic_block a
,basic_block b
)
606 /* If we are partitioning hot/cold basic blocks, we don't want to
607 mess up unconditional or indirect jumps that cross between hot
610 Basic block partitioning may result in some jumps that appear to
611 be optimizable (or blocks that appear to be mergeable), but which really
612 must be left untouched (they are required to make it safely across
613 partition boundaries). See the comments at the top of
614 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
616 if (flag_reorder_blocks_and_partition
617 && (find_reg_note (BB_END (a
), REG_CROSSING_JUMP
, NULL_RTX
)
618 || find_reg_note (BB_END (b
), REG_CROSSING_JUMP
, NULL_RTX
)
619 || BB_PARTITION (a
) != BB_PARTITION (b
)))
622 /* There must be exactly one edge in between the blocks. */
623 return (EDGE_COUNT (a
->succs
) == 1
624 && EDGE_SUCC (a
, 0)->dest
== b
625 && EDGE_COUNT (b
->preds
) == 1
627 /* Must be simple edge. */
628 && !(EDGE_SUCC (a
, 0)->flags
& EDGE_COMPLEX
)
630 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
631 /* If the jump insn has side effects,
632 we can't kill the edge. */
633 && (!JUMP_P (BB_END (a
))
635 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
638 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
642 block_label (basic_block block
)
644 if (block
== EXIT_BLOCK_PTR
)
647 if (!LABEL_P (BB_HEAD (block
)))
649 BB_HEAD (block
) = emit_label_before (gen_label_rtx (), BB_HEAD (block
));
652 return BB_HEAD (block
);
655 /* Attempt to perform edge redirection by replacing possibly complex jump
656 instruction by unconditional jump or removing jump completely. This can
657 apply only if all edges now point to the same block. The parameters and
658 return values are equivalent to redirect_edge_and_branch. */
661 try_redirect_by_replacing_jump (edge e
, basic_block target
, bool in_cfglayout
)
663 basic_block src
= e
->src
;
664 rtx insn
= BB_END (src
), kill_from
;
668 /* If we are partitioning hot/cold basic blocks, we don't want to
669 mess up unconditional or indirect jumps that cross between hot
672 Basic block partitioning may result in some jumps that appear to
673 be optimizable (or blocks that appear to be mergeable), but which really
674 must be left untouched (they are required to make it safely across
675 partition boundaries). See the comments at the top of
676 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
678 if (flag_reorder_blocks_and_partition
679 && (find_reg_note (insn
, REG_CROSSING_JUMP
, NULL_RTX
)
680 || BB_PARTITION (src
) != BB_PARTITION (target
)))
683 /* We can replace or remove a complex jump only when we have exactly
684 two edges. Also, if we have exactly one outgoing edge, we can
686 if (EDGE_COUNT (src
->succs
) >= 3
687 /* Verify that all targets will be TARGET. Specifically, the
688 edge that is not E must also go to TARGET. */
689 || (EDGE_COUNT (src
->succs
) == 2
690 && EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
)->dest
!= target
))
693 if (!onlyjump_p (insn
))
695 if ((!optimize
|| reload_completed
) && tablejump_p (insn
, NULL
, NULL
))
698 /* Avoid removing branch with side effects. */
699 set
= single_set (insn
);
700 if (!set
|| side_effects_p (set
))
703 /* In case we zap a conditional jump, we'll need to kill
704 the cc0 setter too. */
707 if (reg_mentioned_p (cc0_rtx
, PATTERN (insn
)))
708 kill_from
= PREV_INSN (insn
);
711 /* See if we can create the fallthru edge. */
712 if (in_cfglayout
|| can_fallthru (src
, target
))
715 fprintf (dump_file
, "Removing jump %i.\n", INSN_UID (insn
));
718 /* Selectively unlink whole insn chain. */
721 rtx insn
= src
->rbi
->footer
;
723 delete_insn_chain (kill_from
, BB_END (src
));
725 /* Remove barriers but keep jumptables. */
728 if (BARRIER_P (insn
))
730 if (PREV_INSN (insn
))
731 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
733 src
->rbi
->footer
= NEXT_INSN (insn
);
734 if (NEXT_INSN (insn
))
735 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
739 insn
= NEXT_INSN (insn
);
743 delete_insn_chain (kill_from
, PREV_INSN (BB_HEAD (target
)));
746 /* If this already is simplejump, redirect it. */
747 else if (simplejump_p (insn
))
749 if (e
->dest
== target
)
752 fprintf (dump_file
, "Redirecting jump %i from %i to %i.\n",
753 INSN_UID (insn
), e
->dest
->index
, target
->index
);
754 if (!redirect_jump (insn
, block_label (target
), 0))
756 gcc_assert (target
== EXIT_BLOCK_PTR
);
761 /* Cannot do anything for target exit block. */
762 else if (target
== EXIT_BLOCK_PTR
)
765 /* Or replace possibly complicated jump insn by simple jump insn. */
768 rtx target_label
= block_label (target
);
769 rtx barrier
, label
, table
;
771 emit_jump_insn_after_noloc (gen_jump (target_label
), insn
);
772 JUMP_LABEL (BB_END (src
)) = target_label
;
773 LABEL_NUSES (target_label
)++;
775 fprintf (dump_file
, "Replacing insn %i by jump %i\n",
776 INSN_UID (insn
), INSN_UID (BB_END (src
)));
779 delete_insn_chain (kill_from
, insn
);
781 /* Recognize a tablejump that we are converting to a
782 simple jump and remove its associated CODE_LABEL
783 and ADDR_VEC or ADDR_DIFF_VEC. */
784 if (tablejump_p (insn
, &label
, &table
))
785 delete_insn_chain (label
, table
);
787 barrier
= next_nonnote_insn (BB_END (src
));
788 if (!barrier
|| !BARRIER_P (barrier
))
789 emit_barrier_after (BB_END (src
));
792 if (barrier
!= NEXT_INSN (BB_END (src
)))
794 /* Move the jump before barrier so that the notes
795 which originally were or were created before jump table are
796 inside the basic block. */
797 rtx new_insn
= BB_END (src
);
800 for (tmp
= NEXT_INSN (BB_END (src
)); tmp
!= barrier
;
801 tmp
= NEXT_INSN (tmp
))
802 set_block_for_insn (tmp
, src
);
804 NEXT_INSN (PREV_INSN (new_insn
)) = NEXT_INSN (new_insn
);
805 PREV_INSN (NEXT_INSN (new_insn
)) = PREV_INSN (new_insn
);
807 NEXT_INSN (new_insn
) = barrier
;
808 NEXT_INSN (PREV_INSN (barrier
)) = new_insn
;
810 PREV_INSN (new_insn
) = PREV_INSN (barrier
);
811 PREV_INSN (barrier
) = new_insn
;
816 /* Keep only one edge out and set proper flags. */
817 while (EDGE_COUNT (src
->succs
) > 1)
820 e
= EDGE_SUCC (src
, 0);
822 e
->flags
= EDGE_FALLTHRU
;
826 e
->probability
= REG_BR_PROB_BASE
;
827 e
->count
= src
->count
;
829 /* We don't want a block to end on a line-number note since that has
830 the potential of changing the code between -g and not -g. */
831 while (NOTE_P (BB_END (e
->src
))
832 && NOTE_LINE_NUMBER (BB_END (e
->src
)) >= 0)
833 delete_insn (BB_END (e
->src
));
835 if (e
->dest
!= target
)
836 redirect_edge_succ (e
, target
);
841 /* Return last loop_beg note appearing after INSN, before start of next
842 basic block. Return INSN if there are no such notes.
844 When emitting jump to redirect a fallthru edge, it should always appear
845 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
846 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
850 last_loop_beg_note (rtx insn
)
854 for (insn
= NEXT_INSN (insn
); insn
&& NOTE_P (insn
)
855 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
;
856 insn
= NEXT_INSN (insn
))
857 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
863 /* Redirect edge representing branch of (un)conditional jump or tablejump,
866 redirect_branch_edge (edge e
, basic_block target
)
869 rtx old_label
= BB_HEAD (e
->dest
);
870 basic_block src
= e
->src
;
871 rtx insn
= BB_END (src
);
873 /* We can only redirect non-fallthru edges of jump insn. */
874 if (e
->flags
& EDGE_FALLTHRU
)
876 else if (!JUMP_P (insn
))
879 /* Recognize a tablejump and adjust all matching cases. */
880 if (tablejump_p (insn
, NULL
, &tmp
))
884 rtx new_label
= block_label (target
);
886 if (target
== EXIT_BLOCK_PTR
)
888 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
889 vec
= XVEC (PATTERN (tmp
), 0);
891 vec
= XVEC (PATTERN (tmp
), 1);
893 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
894 if (XEXP (RTVEC_ELT (vec
, j
), 0) == old_label
)
896 RTVEC_ELT (vec
, j
) = gen_rtx_LABEL_REF (Pmode
, new_label
);
897 --LABEL_NUSES (old_label
);
898 ++LABEL_NUSES (new_label
);
901 /* Handle casesi dispatch insns. */
902 if ((tmp
= single_set (insn
)) != NULL
903 && SET_DEST (tmp
) == pc_rtx
904 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
905 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
906 && XEXP (XEXP (SET_SRC (tmp
), 2), 0) == old_label
)
908 XEXP (SET_SRC (tmp
), 2) = gen_rtx_LABEL_REF (VOIDmode
,
910 --LABEL_NUSES (old_label
);
911 ++LABEL_NUSES (new_label
);
916 /* ?? We may play the games with moving the named labels from
917 one basic block to the other in case only one computed_jump is
919 if (computed_jump_p (insn
)
920 /* A return instruction can't be redirected. */
921 || returnjump_p (insn
))
924 /* If the insn doesn't go where we think, we're confused. */
925 gcc_assert (JUMP_LABEL (insn
) == old_label
);
927 /* If the substitution doesn't succeed, die. This can happen
928 if the back end emitted unrecognizable instructions or if
929 target is exit block on some arches. */
930 if (!redirect_jump (insn
, block_label (target
), 0))
932 gcc_assert (target
== EXIT_BLOCK_PTR
);
938 fprintf (dump_file
, "Edge %i->%i redirected to %i\n",
939 e
->src
->index
, e
->dest
->index
, target
->index
);
941 if (e
->dest
!= target
)
942 e
= redirect_edge_succ_nodup (e
, target
);
946 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
947 expense of adding new instructions or reordering basic blocks.
949 Function can be also called with edge destination equivalent to the TARGET.
950 Then it should try the simplifications and do nothing if none is possible.
952 Return edge representing the branch if transformation succeeded. Return NULL
954 We still return NULL in case E already destinated TARGET and we didn't
955 managed to simplify instruction stream. */
958 rtl_redirect_edge_and_branch (edge e
, basic_block target
)
961 basic_block src
= e
->src
;
963 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
966 if (e
->dest
== target
)
969 if ((ret
= try_redirect_by_replacing_jump (e
, target
, false)) != NULL
)
971 src
->flags
|= BB_DIRTY
;
975 ret
= redirect_branch_edge (e
, target
);
979 src
->flags
|= BB_DIRTY
;
983 /* Like force_nonfallthru below, but additionally performs redirection
984 Used by redirect_edge_and_branch_force. */
987 force_nonfallthru_and_redirect (edge e
, basic_block target
)
989 basic_block jump_block
, new_bb
= NULL
, src
= e
->src
;
992 int abnormal_edge_flags
= 0;
994 /* In the case the last instruction is conditional jump to the next
995 instruction, first redirect the jump itself and then continue
996 by creating a basic block afterwards to redirect fallthru edge. */
997 if (e
->src
!= ENTRY_BLOCK_PTR
&& e
->dest
!= EXIT_BLOCK_PTR
998 && any_condjump_p (BB_END (e
->src
))
999 /* When called from cfglayout, fallthru edges do not
1000 necessarily go to the next block. */
1001 && e
->src
->next_bb
== e
->dest
1002 && JUMP_LABEL (BB_END (e
->src
)) == BB_HEAD (e
->dest
))
1005 edge b
= unchecked_make_edge (e
->src
, target
, 0);
1008 redirected
= redirect_jump (BB_END (e
->src
), block_label (target
), 0);
1009 gcc_assert (redirected
);
1011 note
= find_reg_note (BB_END (e
->src
), REG_BR_PROB
, NULL_RTX
);
1014 int prob
= INTVAL (XEXP (note
, 0));
1016 b
->probability
= prob
;
1017 b
->count
= e
->count
* prob
/ REG_BR_PROB_BASE
;
1018 e
->probability
-= e
->probability
;
1019 e
->count
-= b
->count
;
1020 if (e
->probability
< 0)
1027 if (e
->flags
& EDGE_ABNORMAL
)
1029 /* Irritating special case - fallthru edge to the same block as abnormal
1031 We can't redirect abnormal edge, but we still can split the fallthru
1032 one and create separate abnormal edge to original destination.
1033 This allows bb-reorder to make such edge non-fallthru. */
1034 gcc_assert (e
->dest
== target
);
1035 abnormal_edge_flags
= e
->flags
& ~(EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
);
1036 e
->flags
&= EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
;
1040 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1041 if (e
->src
== ENTRY_BLOCK_PTR
)
1043 /* We can't redirect the entry block. Create an empty block
1044 at the start of the function which we use to add the new
1050 basic_block bb
= create_basic_block (BB_HEAD (e
->dest
), NULL
, ENTRY_BLOCK_PTR
);
1052 /* Change the existing edge's source to be the new block, and add
1053 a new edge from the entry block to the new block. */
1055 for (ei
= ei_start (ENTRY_BLOCK_PTR
->succs
); (tmp
= ei_safe_edge (ei
)); )
1059 VEC_unordered_remove (edge
, ENTRY_BLOCK_PTR
->succs
, ei
.index
);
1069 VEC_safe_push (edge
, bb
->succs
, e
);
1070 make_single_succ_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_FALLTHRU
);
1074 if (EDGE_COUNT (e
->src
->succs
) >= 2 || abnormal_edge_flags
)
1076 /* Create the new structures. */
1078 /* If the old block ended with a tablejump, skip its table
1079 by searching forward from there. Otherwise start searching
1080 forward from the last instruction of the old block. */
1081 if (!tablejump_p (BB_END (e
->src
), NULL
, ¬e
))
1082 note
= BB_END (e
->src
);
1084 /* Position the new block correctly relative to loop notes. */
1085 note
= last_loop_beg_note (note
);
1086 note
= NEXT_INSN (note
);
1088 jump_block
= create_basic_block (note
, NULL
, e
->src
);
1089 jump_block
->count
= e
->count
;
1090 jump_block
->frequency
= EDGE_FREQUENCY (e
);
1091 jump_block
->loop_depth
= target
->loop_depth
;
1093 if (target
->global_live_at_start
)
1095 jump_block
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1096 jump_block
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1097 COPY_REG_SET (jump_block
->global_live_at_start
,
1098 target
->global_live_at_start
);
1099 COPY_REG_SET (jump_block
->global_live_at_end
,
1100 target
->global_live_at_start
);
1103 /* Make sure new block ends up in correct hot/cold section. */
1105 BB_COPY_PARTITION (jump_block
, e
->src
);
1106 if (flag_reorder_blocks_and_partition
1107 && targetm
.have_named_sections
)
1109 if (BB_PARTITION (jump_block
) == BB_COLD_PARTITION
)
1111 rtx bb_note
, new_note
;
1112 for (bb_note
= BB_HEAD (jump_block
);
1113 bb_note
&& bb_note
!= NEXT_INSN (BB_END (jump_block
));
1114 bb_note
= NEXT_INSN (bb_note
))
1115 if (NOTE_P (bb_note
)
1116 && NOTE_LINE_NUMBER (bb_note
) == NOTE_INSN_BASIC_BLOCK
)
1118 new_note
= emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE
,
1120 NOTE_BASIC_BLOCK (new_note
) = jump_block
;
1122 if (JUMP_P (BB_END (jump_block
))
1123 && !any_condjump_p (BB_END (jump_block
))
1124 && (EDGE_SUCC (jump_block
, 0)->flags
& EDGE_CROSSING
))
1125 REG_NOTES (BB_END (jump_block
)) = gen_rtx_EXPR_LIST
1126 (REG_CROSSING_JUMP
, NULL_RTX
,
1127 REG_NOTES (BB_END (jump_block
)));
1131 new_edge
= make_edge (e
->src
, jump_block
, EDGE_FALLTHRU
);
1132 new_edge
->probability
= e
->probability
;
1133 new_edge
->count
= e
->count
;
1135 /* Redirect old edge. */
1136 redirect_edge_pred (e
, jump_block
);
1137 e
->probability
= REG_BR_PROB_BASE
;
1139 new_bb
= jump_block
;
1142 jump_block
= e
->src
;
1144 e
->flags
&= ~EDGE_FALLTHRU
;
1145 if (target
== EXIT_BLOCK_PTR
)
1148 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block
));
1155 rtx label
= block_label (target
);
1156 emit_jump_insn_after_noloc (gen_jump (label
), BB_END (jump_block
));
1157 JUMP_LABEL (BB_END (jump_block
)) = label
;
1158 LABEL_NUSES (label
)++;
1161 emit_barrier_after (BB_END (jump_block
));
1162 redirect_edge_succ_nodup (e
, target
);
1164 if (abnormal_edge_flags
)
1165 make_edge (src
, target
, abnormal_edge_flags
);
1170 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1171 (and possibly create new basic block) to make edge non-fallthru.
1172 Return newly created BB or NULL if none. */
1175 force_nonfallthru (edge e
)
1177 return force_nonfallthru_and_redirect (e
, e
->dest
);
1180 /* Redirect edge even at the expense of creating new jump insn or
1181 basic block. Return new basic block if created, NULL otherwise.
1182 Abort if conversion is impossible. */
1185 rtl_redirect_edge_and_branch_force (edge e
, basic_block target
)
1187 if (redirect_edge_and_branch (e
, target
)
1188 || e
->dest
== target
)
1191 /* In case the edge redirection failed, try to force it to be non-fallthru
1192 and redirect newly created simplejump. */
1193 return force_nonfallthru_and_redirect (e
, target
);
1196 /* The given edge should potentially be a fallthru edge. If that is in
1197 fact true, delete the jump and barriers that are in the way. */
1200 rtl_tidy_fallthru_edge (edge e
)
1203 basic_block b
= e
->src
, c
= b
->next_bb
;
1205 /* ??? In a late-running flow pass, other folks may have deleted basic
1206 blocks by nopping out blocks, leaving multiple BARRIERs between here
1207 and the target label. They ought to be chastized and fixed.
1209 We can also wind up with a sequence of undeletable labels between
1210 one block and the next.
1212 So search through a sequence of barriers, labels, and notes for
1213 the head of block C and assert that we really do fall through. */
1215 for (q
= NEXT_INSN (BB_END (b
)); q
!= BB_HEAD (c
); q
= NEXT_INSN (q
))
1219 /* Remove what will soon cease being the jump insn from the source block.
1220 If block B consisted only of this single jump, turn it into a deleted
1225 && (any_uncondjump_p (q
)
1226 || EDGE_COUNT (b
->succs
) == 1))
1229 /* If this was a conditional jump, we need to also delete
1230 the insn that set cc0. */
1231 if (any_condjump_p (q
) && only_sets_cc0_p (PREV_INSN (q
)))
1237 /* We don't want a block to end on a line-number note since that has
1238 the potential of changing the code between -g and not -g. */
1239 while (NOTE_P (q
) && NOTE_LINE_NUMBER (q
) >= 0)
1243 /* Selectively unlink the sequence. */
1244 if (q
!= PREV_INSN (BB_HEAD (c
)))
1245 delete_insn_chain (NEXT_INSN (q
), PREV_INSN (BB_HEAD (c
)));
1247 e
->flags
|= EDGE_FALLTHRU
;
1250 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1251 is back edge of syntactic loop. */
1254 back_edge_of_syntactic_loop_p (basic_block bb1
, basic_block bb2
)
1263 /* ??? Could we guarantee that bb indices are monotone, so that we could
1264 just compare them? */
1265 for (bb
= bb1
; bb
&& bb
!= bb2
; bb
= bb
->next_bb
)
1271 for (insn
= BB_END (bb1
); insn
!= BB_HEAD (bb2
) && count
>= 0;
1272 insn
= NEXT_INSN (insn
))
1275 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1277 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1284 /* Should move basic block BB after basic block AFTER. NIY. */
1287 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED
,
1288 basic_block after ATTRIBUTE_UNUSED
)
1293 /* Split a (typically critical) edge. Return the new block.
1294 Abort on abnormal edges.
1296 ??? The code generally expects to be called on critical edges.
1297 The case of a block ending in an unconditional jump to a
1298 block with multiple predecessors is not handled optimally. */
1301 rtl_split_edge (edge edge_in
)
1306 /* Abnormal edges cannot be split. */
1307 gcc_assert (!(edge_in
->flags
& EDGE_ABNORMAL
));
1309 /* We are going to place the new block in front of edge destination.
1310 Avoid existence of fallthru predecessors. */
1311 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1316 FOR_EACH_EDGE (e
, ei
, edge_in
->dest
->preds
)
1317 if (e
->flags
& EDGE_FALLTHRU
)
1321 force_nonfallthru (e
);
1324 /* Create the basic block note.
1326 Where we place the note can have a noticeable impact on the generated
1327 code. Consider this cfg:
1337 If we need to insert an insn on the edge from block 0 to block 1,
1338 we want to ensure the instructions we insert are outside of any
1339 loop notes that physically sit between block 0 and block 1. Otherwise
1340 we confuse the loop optimizer into thinking the loop is a phony. */
1342 if (edge_in
->dest
!= EXIT_BLOCK_PTR
1343 && PREV_INSN (BB_HEAD (edge_in
->dest
))
1344 && NOTE_P (PREV_INSN (BB_HEAD (edge_in
->dest
)))
1345 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in
->dest
)))
1346 == NOTE_INSN_LOOP_BEG
)
1347 && !back_edge_of_syntactic_loop_p (edge_in
->dest
, edge_in
->src
))
1348 before
= PREV_INSN (BB_HEAD (edge_in
->dest
));
1349 else if (edge_in
->dest
!= EXIT_BLOCK_PTR
)
1350 before
= BB_HEAD (edge_in
->dest
);
1354 /* If this is a fall through edge to the exit block, the blocks might be
1355 not adjacent, and the right place is the after the source. */
1356 if (edge_in
->flags
& EDGE_FALLTHRU
&& edge_in
->dest
== EXIT_BLOCK_PTR
)
1358 before
= NEXT_INSN (BB_END (edge_in
->src
));
1361 && NOTE_LINE_NUMBER (before
) == NOTE_INSN_LOOP_END
)
1362 before
= NEXT_INSN (before
);
1363 bb
= create_basic_block (before
, NULL
, edge_in
->src
);
1364 BB_COPY_PARTITION (bb
, edge_in
->src
);
1368 bb
= create_basic_block (before
, NULL
, edge_in
->dest
->prev_bb
);
1369 /* ??? Why not edge_in->dest->prev_bb here? */
1370 BB_COPY_PARTITION (bb
, edge_in
->dest
);
1373 /* ??? This info is likely going to be out of date very soon. */
1374 if (edge_in
->dest
->global_live_at_start
)
1376 bb
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1377 bb
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1378 COPY_REG_SET (bb
->global_live_at_start
,
1379 edge_in
->dest
->global_live_at_start
);
1380 COPY_REG_SET (bb
->global_live_at_end
,
1381 edge_in
->dest
->global_live_at_start
);
1384 make_single_succ_edge (bb
, edge_in
->dest
, EDGE_FALLTHRU
);
1386 /* For non-fallthru edges, we must adjust the predecessor's
1387 jump instruction to target our new block. */
1388 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1390 edge redirected
= redirect_edge_and_branch (edge_in
, bb
);
1391 gcc_assert (redirected
);
1394 redirect_edge_succ (edge_in
, bb
);
1399 /* Queue instructions for insertion on an edge between two basic blocks.
1400 The new instructions and basic blocks (if any) will not appear in the
1401 CFG until commit_edge_insertions is called. */
1404 insert_insn_on_edge (rtx pattern
, edge e
)
1406 /* We cannot insert instructions on an abnormal critical edge.
1407 It will be easier to find the culprit if we die now. */
1408 gcc_assert (!((e
->flags
& EDGE_ABNORMAL
) && EDGE_CRITICAL_P (e
)));
1410 if (e
->insns
.r
== NULL_RTX
)
1413 push_to_sequence (e
->insns
.r
);
1415 emit_insn (pattern
);
1417 e
->insns
.r
= get_insns ();
1421 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1422 registers that are killed by the store. */
1424 mark_killed_regs (rtx reg
, rtx set ATTRIBUTE_UNUSED
, void *data
)
1426 regset killed
= data
;
1429 if (GET_CODE (reg
) == SUBREG
)
1430 reg
= SUBREG_REG (reg
);
1433 regno
= REGNO (reg
);
1434 if (regno
>= FIRST_PSEUDO_REGISTER
)
1435 SET_REGNO_REG_SET (killed
, regno
);
1438 for (i
= 0; i
< (int) hard_regno_nregs
[regno
][GET_MODE (reg
)]; i
++)
1439 SET_REGNO_REG_SET (killed
, regno
+ i
);
1443 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1444 it checks whether this will not clobber the registers that are live on the
1445 edge (i.e. it requires liveness information to be up-to-date) and if there
1446 are some, then it tries to save and restore them. Returns true if
1449 safe_insert_insn_on_edge (rtx insn
, edge e
)
1453 rtx save_regs
= NULL_RTX
;
1456 enum machine_mode mode
;
1457 reg_set_iterator rsi
;
1459 #ifdef AVOID_CCMODE_COPIES
1465 killed
= ALLOC_REG_SET (®_obstack
);
1467 for (x
= insn
; x
; x
= NEXT_INSN (x
))
1469 note_stores (PATTERN (x
), mark_killed_regs
, killed
);
1470 bitmap_and_into (killed
, e
->dest
->global_live_at_start
);
1472 EXECUTE_IF_SET_IN_REG_SET (killed
, 0, regno
, rsi
)
1474 mode
= regno
< FIRST_PSEUDO_REGISTER
1475 ? reg_raw_mode
[regno
]
1476 : GET_MODE (regno_reg_rtx
[regno
]);
1477 if (mode
== VOIDmode
)
1480 if (noccmode
&& mode
== CCmode
)
1483 save_regs
= alloc_EXPR_LIST (0,
1486 gen_raw_REG (mode
, regno
)),
1495 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1497 from
= XEXP (XEXP (x
, 0), 1);
1498 to
= XEXP (XEXP (x
, 0), 0);
1499 emit_move_insn (to
, from
);
1502 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1504 from
= XEXP (XEXP (x
, 0), 0);
1505 to
= XEXP (XEXP (x
, 0), 1);
1506 emit_move_insn (to
, from
);
1508 insn
= get_insns ();
1510 free_EXPR_LIST_list (&save_regs
);
1512 insert_insn_on_edge (insn
, e
);
1514 FREE_REG_SET (killed
);
1518 /* Update the CFG for the instructions queued on edge E. */
1521 commit_one_edge_insertion (edge e
, int watch_calls
)
1523 rtx before
= NULL_RTX
, after
= NULL_RTX
, insns
, tmp
, last
;
1524 basic_block bb
= NULL
;
1526 /* Pull the insns off the edge now since the edge might go away. */
1528 e
->insns
.r
= NULL_RTX
;
1530 /* Special case -- avoid inserting code between call and storing
1531 its return value. */
1532 if (watch_calls
&& (e
->flags
& EDGE_FALLTHRU
)
1533 && EDGE_COUNT (e
->dest
->preds
) == 1
1534 && e
->src
!= ENTRY_BLOCK_PTR
1535 && CALL_P (BB_END (e
->src
)))
1537 rtx next
= next_nonnote_insn (BB_END (e
->src
));
1539 after
= BB_HEAD (e
->dest
);
1540 /* The first insn after the call may be a stack pop, skip it. */
1542 && keep_with_call_p (next
))
1545 next
= next_nonnote_insn (next
);
1549 if (!before
&& !after
)
1551 /* Figure out where to put these things. If the destination has
1552 one predecessor, insert there. Except for the exit block. */
1553 if (EDGE_COUNT (e
->dest
->preds
) == 1 && e
->dest
!= EXIT_BLOCK_PTR
)
1557 /* Get the location correct wrt a code label, and "nice" wrt
1558 a basic block note, and before everything else. */
1561 tmp
= NEXT_INSN (tmp
);
1562 if (NOTE_INSN_BASIC_BLOCK_P (tmp
))
1563 tmp
= NEXT_INSN (tmp
);
1566 && NOTE_LINE_NUMBER (tmp
) == NOTE_INSN_UNLIKELY_EXECUTED_CODE
)
1567 tmp
= NEXT_INSN (tmp
);
1568 if (tmp
== BB_HEAD (bb
))
1571 after
= PREV_INSN (tmp
);
1573 after
= get_last_insn ();
1576 /* If the source has one successor and the edge is not abnormal,
1577 insert there. Except for the entry block. */
1578 else if ((e
->flags
& EDGE_ABNORMAL
) == 0
1579 && EDGE_COUNT (e
->src
->succs
) == 1
1580 && e
->src
!= ENTRY_BLOCK_PTR
)
1584 /* It is possible to have a non-simple jump here. Consider a target
1585 where some forms of unconditional jumps clobber a register. This
1586 happens on the fr30 for example.
1588 We know this block has a single successor, so we can just emit
1589 the queued insns before the jump. */
1590 if (JUMP_P (BB_END (bb
)))
1591 for (before
= BB_END (bb
);
1592 NOTE_P (PREV_INSN (before
))
1593 && NOTE_LINE_NUMBER (PREV_INSN (before
)) ==
1594 NOTE_INSN_LOOP_BEG
; before
= PREV_INSN (before
))
1598 /* We'd better be fallthru, or we've lost track of
1600 gcc_assert (e
->flags
& EDGE_FALLTHRU
);
1602 after
= BB_END (bb
);
1605 /* Otherwise we must split the edge. */
1608 bb
= split_edge (e
);
1609 after
= BB_END (bb
);
1611 if (flag_reorder_blocks_and_partition
1612 && targetm
.have_named_sections
1613 && e
->src
!= ENTRY_BLOCK_PTR
1614 && BB_PARTITION (e
->src
) == BB_COLD_PARTITION
1615 && !(e
->flags
& EDGE_CROSSING
))
1617 rtx bb_note
, new_note
, cur_insn
;
1620 for (cur_insn
= BB_HEAD (bb
); cur_insn
!= NEXT_INSN (BB_END (bb
));
1621 cur_insn
= NEXT_INSN (cur_insn
))
1622 if (NOTE_P (cur_insn
)
1623 && NOTE_LINE_NUMBER (cur_insn
) == NOTE_INSN_BASIC_BLOCK
)
1629 new_note
= emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE
,
1631 NOTE_BASIC_BLOCK (new_note
) = bb
;
1632 if (JUMP_P (BB_END (bb
))
1633 && !any_condjump_p (BB_END (bb
))
1634 && (EDGE_SUCC (bb
, 0)->flags
& EDGE_CROSSING
))
1635 REG_NOTES (BB_END (bb
)) = gen_rtx_EXPR_LIST
1636 (REG_CROSSING_JUMP
, NULL_RTX
, REG_NOTES (BB_END (bb
)));
1637 if (after
== bb_note
)
1643 /* Now that we've found the spot, do the insertion. */
1647 emit_insn_before_noloc (insns
, before
);
1648 last
= prev_nonnote_insn (before
);
1651 last
= emit_insn_after_noloc (insns
, after
);
1653 if (returnjump_p (last
))
1655 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1656 This is not currently a problem because this only happens
1657 for the (single) epilogue, which already has a fallthru edge
1660 e
= EDGE_SUCC (bb
, 0);
1661 gcc_assert (e
->dest
== EXIT_BLOCK_PTR
1662 && EDGE_COUNT (bb
->succs
) == 1 && (e
->flags
& EDGE_FALLTHRU
));
1664 e
->flags
&= ~EDGE_FALLTHRU
;
1665 emit_barrier_after (last
);
1668 delete_insn (before
);
1671 gcc_assert (!JUMP_P (last
));
1673 /* Mark the basic block for find_sub_basic_blocks. */
1677 /* Update the CFG for all queued instructions. */
1680 commit_edge_insertions (void)
1684 bool changed
= false;
1686 #ifdef ENABLE_CHECKING
1687 verify_flow_info ();
1690 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1695 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1699 commit_one_edge_insertion (e
, false);
1706 blocks
= sbitmap_alloc (last_basic_block
);
1707 sbitmap_zero (blocks
);
1711 SET_BIT (blocks
, bb
->index
);
1712 /* Check for forgotten bb->aux values before commit_edge_insertions
1714 gcc_assert (bb
->aux
== &bb
->aux
);
1717 find_many_sub_basic_blocks (blocks
);
1718 sbitmap_free (blocks
);
1721 /* Update the CFG for all queued instructions, taking special care of inserting
1722 code on edges between call and storing its return value. */
1725 commit_edge_insertions_watch_calls (void)
1729 bool changed
= false;
1731 #ifdef ENABLE_CHECKING
1732 verify_flow_info ();
1735 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1740 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1744 commit_one_edge_insertion (e
, true);
1751 blocks
= sbitmap_alloc (last_basic_block
);
1752 sbitmap_zero (blocks
);
1756 SET_BIT (blocks
, bb
->index
);
1757 /* Check for forgotten bb->aux values before commit_edge_insertions
1759 gcc_assert (bb
->aux
== &bb
->aux
);
1762 find_many_sub_basic_blocks (blocks
);
1763 sbitmap_free (blocks
);
1766 /* Print out RTL-specific basic block information (live information
1767 at start and end). */
1770 rtl_dump_bb (basic_block bb
, FILE *outf
, int indent
)
1776 s_indent
= alloca ((size_t) indent
+ 1);
1777 memset (s_indent
, ' ', (size_t) indent
);
1778 s_indent
[indent
] = '\0';
1780 fprintf (outf
, ";;%s Registers live at start: ", s_indent
);
1781 dump_regset (bb
->global_live_at_start
, outf
);
1784 for (insn
= BB_HEAD (bb
), last
= NEXT_INSN (BB_END (bb
)); insn
!= last
;
1785 insn
= NEXT_INSN (insn
))
1786 print_rtl_single (outf
, insn
);
1788 fprintf (outf
, ";;%s Registers live at end: ", s_indent
);
1789 dump_regset (bb
->global_live_at_end
, outf
);
1793 /* Like print_rtl, but also print out live information for the start of each
1797 print_rtl_with_bb (FILE *outf
, rtx rtx_first
)
1802 fprintf (outf
, "(nil)\n");
1805 enum bb_state
{ NOT_IN_BB
, IN_ONE_BB
, IN_MULTIPLE_BB
};
1806 int max_uid
= get_max_uid ();
1807 basic_block
*start
= xcalloc (max_uid
, sizeof (basic_block
));
1808 basic_block
*end
= xcalloc (max_uid
, sizeof (basic_block
));
1809 enum bb_state
*in_bb_p
= xcalloc (max_uid
, sizeof (enum bb_state
));
1813 FOR_EACH_BB_REVERSE (bb
)
1817 start
[INSN_UID (BB_HEAD (bb
))] = bb
;
1818 end
[INSN_UID (BB_END (bb
))] = bb
;
1819 for (x
= BB_HEAD (bb
); x
!= NULL_RTX
; x
= NEXT_INSN (x
))
1821 enum bb_state state
= IN_MULTIPLE_BB
;
1823 if (in_bb_p
[INSN_UID (x
)] == NOT_IN_BB
)
1825 in_bb_p
[INSN_UID (x
)] = state
;
1827 if (x
== BB_END (bb
))
1832 for (tmp_rtx
= rtx_first
; NULL
!= tmp_rtx
; tmp_rtx
= NEXT_INSN (tmp_rtx
))
1836 if ((bb
= start
[INSN_UID (tmp_rtx
)]) != NULL
)
1838 fprintf (outf
, ";; Start of basic block %d, registers live:",
1840 dump_regset (bb
->global_live_at_start
, outf
);
1844 if (in_bb_p
[INSN_UID (tmp_rtx
)] == NOT_IN_BB
1845 && !NOTE_P (tmp_rtx
)
1846 && !BARRIER_P (tmp_rtx
))
1847 fprintf (outf
, ";; Insn is not within a basic block\n");
1848 else if (in_bb_p
[INSN_UID (tmp_rtx
)] == IN_MULTIPLE_BB
)
1849 fprintf (outf
, ";; Insn is in multiple basic blocks\n");
1851 did_output
= print_rtl_single (outf
, tmp_rtx
);
1853 if ((bb
= end
[INSN_UID (tmp_rtx
)]) != NULL
)
1855 fprintf (outf
, ";; End of basic block %d, registers live:\n",
1857 dump_regset (bb
->global_live_at_end
, outf
);
1870 if (current_function_epilogue_delay_list
!= 0)
1872 fprintf (outf
, "\n;; Insns in epilogue delay list:\n\n");
1873 for (tmp_rtx
= current_function_epilogue_delay_list
; tmp_rtx
!= 0;
1874 tmp_rtx
= XEXP (tmp_rtx
, 1))
1875 print_rtl_single (outf
, XEXP (tmp_rtx
, 0));
1880 update_br_prob_note (basic_block bb
)
1883 if (!JUMP_P (BB_END (bb
)))
1885 note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
);
1886 if (!note
|| INTVAL (XEXP (note
, 0)) == BRANCH_EDGE (bb
)->probability
)
1888 XEXP (note
, 0) = GEN_INT (BRANCH_EDGE (bb
)->probability
);
1891 /* Verify the CFG and RTL consistency common for both underlying RTL and
1894 Currently it does following checks:
1896 - test head/end pointers
1897 - overlapping of basic blocks
1898 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1899 - tails of basic blocks (ensure that boundary is necessary)
1900 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1901 and NOTE_INSN_BASIC_BLOCK
1902 - verify that no fall_thru edge crosses hot/cold partition boundaries
1904 In future it can be extended check a lot of other stuff as well
1905 (reachability of basic blocks, life information, etc. etc.). */
1908 rtl_verify_flow_info_1 (void)
1910 const int max_uid
= get_max_uid ();
1911 rtx last_head
= get_last_insn ();
1912 basic_block
*bb_info
;
1915 basic_block bb
, last_bb_seen
;
1917 bb_info
= xcalloc (max_uid
, sizeof (basic_block
));
1919 /* Check bb chain & numbers. */
1920 last_bb_seen
= ENTRY_BLOCK_PTR
;
1922 FOR_EACH_BB_REVERSE (bb
)
1924 rtx head
= BB_HEAD (bb
);
1925 rtx end
= BB_END (bb
);
1927 /* Verify the end of the basic block is in the INSN chain. */
1928 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1934 error ("end insn %d for block %d not found in the insn stream",
1935 INSN_UID (end
), bb
->index
);
1939 /* Work backwards from the end to the head of the basic block
1940 to verify the head is in the RTL chain. */
1941 for (; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1943 /* While walking over the insn chain, verify insns appear
1944 in only one basic block and initialize the BB_INFO array
1945 used by other passes. */
1946 if (bb_info
[INSN_UID (x
)] != NULL
)
1948 error ("insn %d is in multiple basic blocks (%d and %d)",
1949 INSN_UID (x
), bb
->index
, bb_info
[INSN_UID (x
)]->index
);
1953 bb_info
[INSN_UID (x
)] = bb
;
1960 error ("head insn %d for block %d not found in the insn stream",
1961 INSN_UID (head
), bb
->index
);
1968 /* Now check the basic blocks (boundaries etc.) */
1969 FOR_EACH_BB_REVERSE (bb
)
1971 int n_fallthru
= 0, n_eh
= 0, n_call
= 0, n_abnormal
= 0, n_branch
= 0;
1972 edge e
, fallthru
= NULL
;
1976 if (JUMP_P (BB_END (bb
))
1977 && (note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
))
1978 && EDGE_COUNT (bb
->succs
) >= 2
1979 && any_condjump_p (BB_END (bb
)))
1981 if (INTVAL (XEXP (note
, 0)) != BRANCH_EDGE (bb
)->probability
1982 && profile_status
!= PROFILE_ABSENT
)
1984 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1985 INTVAL (XEXP (note
, 0)), BRANCH_EDGE (bb
)->probability
);
1989 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1991 if (e
->flags
& EDGE_FALLTHRU
)
1993 n_fallthru
++, fallthru
= e
;
1994 if ((e
->flags
& EDGE_CROSSING
)
1995 || (BB_PARTITION (e
->src
) != BB_PARTITION (e
->dest
)
1996 && e
->src
!= ENTRY_BLOCK_PTR
1997 && e
->dest
!= EXIT_BLOCK_PTR
))
1999 error ("Fallthru edge crosses section boundary (bb %i)",
2005 if ((e
->flags
& ~(EDGE_DFS_BACK
2007 | EDGE_IRREDUCIBLE_LOOP
2009 | EDGE_CROSSING
)) == 0)
2012 if (e
->flags
& EDGE_ABNORMAL_CALL
)
2015 if (e
->flags
& EDGE_EH
)
2017 else if (e
->flags
& EDGE_ABNORMAL
)
2021 if (n_eh
&& GET_CODE (PATTERN (BB_END (bb
))) != RESX
2022 && !find_reg_note (BB_END (bb
), REG_EH_REGION
, NULL_RTX
))
2024 error ("Missing REG_EH_REGION note in the end of bb %i", bb
->index
);
2028 && (!JUMP_P (BB_END (bb
))
2029 || (n_branch
> 1 && (any_uncondjump_p (BB_END (bb
))
2030 || any_condjump_p (BB_END (bb
))))))
2032 error ("Too many outgoing branch edges from bb %i", bb
->index
);
2035 if (n_fallthru
&& any_uncondjump_p (BB_END (bb
)))
2037 error ("Fallthru edge after unconditional jump %i", bb
->index
);
2040 if (n_branch
!= 1 && any_uncondjump_p (BB_END (bb
)))
2042 error ("Wrong amount of branch edges after unconditional jump %i", bb
->index
);
2045 if (n_branch
!= 1 && any_condjump_p (BB_END (bb
))
2046 && JUMP_LABEL (BB_END (bb
)) != BB_HEAD (fallthru
->dest
))
2048 error ("Wrong amount of branch edges after conditional jump %i", bb
->index
);
2051 if (n_call
&& !CALL_P (BB_END (bb
)))
2053 error ("Call edges for non-call insn in bb %i", bb
->index
);
2057 && (!CALL_P (BB_END (bb
)) && n_call
!= n_abnormal
)
2058 && (!JUMP_P (BB_END (bb
))
2059 || any_condjump_p (BB_END (bb
))
2060 || any_uncondjump_p (BB_END (bb
))))
2062 error ("Abnormal edges for no purpose in bb %i", bb
->index
);
2066 for (x
= BB_HEAD (bb
); x
!= NEXT_INSN (BB_END (bb
)); x
= NEXT_INSN (x
))
2067 /* We may have a barrier inside a basic block before dead code
2068 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2069 if (!BARRIER_P (x
) && BLOCK_FOR_INSN (x
) != bb
)
2072 if (! BLOCK_FOR_INSN (x
))
2074 ("insn %d inside basic block %d but block_for_insn is NULL",
2075 INSN_UID (x
), bb
->index
);
2078 ("insn %d inside basic block %d but block_for_insn is %i",
2079 INSN_UID (x
), bb
->index
, BLOCK_FOR_INSN (x
)->index
);
2084 /* OK pointers are correct. Now check the header of basic
2085 block. It ought to contain optional CODE_LABEL followed
2086 by NOTE_BASIC_BLOCK. */
2090 if (BB_END (bb
) == x
)
2092 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2100 if (!NOTE_INSN_BASIC_BLOCK_P (x
) || NOTE_BASIC_BLOCK (x
) != bb
)
2102 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2107 if (BB_END (bb
) == x
)
2108 /* Do checks for empty blocks here. */
2111 for (x
= NEXT_INSN (x
); x
; x
= NEXT_INSN (x
))
2113 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2115 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2116 INSN_UID (x
), bb
->index
);
2120 if (x
== BB_END (bb
))
2123 if (control_flow_insn_p (x
))
2125 error ("in basic block %d:", bb
->index
);
2126 fatal_insn ("flow control insn inside a basic block", x
);
2136 /* Verify the CFG and RTL consistency common for both underlying RTL and
2139 Currently it does following checks:
2140 - all checks of rtl_verify_flow_info_1
2141 - check that all insns are in the basic blocks
2142 (except the switch handling code, barriers and notes)
2143 - check that all returns are followed by barriers
2144 - check that all fallthru edge points to the adjacent blocks. */
2146 rtl_verify_flow_info (void)
2149 int err
= rtl_verify_flow_info_1 ();
2152 const rtx rtx_first
= get_insns ();
2153 basic_block last_bb_seen
= ENTRY_BLOCK_PTR
, curr_bb
= NULL
;
2155 FOR_EACH_BB_REVERSE (bb
)
2160 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2161 if (e
->flags
& EDGE_FALLTHRU
)
2167 /* Ensure existence of barrier in BB with no fallthru edges. */
2168 for (insn
= BB_END (bb
); !insn
|| !BARRIER_P (insn
);
2169 insn
= NEXT_INSN (insn
))
2172 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BASIC_BLOCK
))
2174 error ("missing barrier after block %i", bb
->index
);
2179 else if (e
->src
!= ENTRY_BLOCK_PTR
2180 && e
->dest
!= EXIT_BLOCK_PTR
)
2184 if (e
->src
->next_bb
!= e
->dest
)
2187 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2188 e
->src
->index
, e
->dest
->index
);
2192 for (insn
= NEXT_INSN (BB_END (e
->src
)); insn
!= BB_HEAD (e
->dest
);
2193 insn
= NEXT_INSN (insn
))
2194 if (BARRIER_P (insn
) || INSN_P (insn
))
2196 error ("verify_flow_info: Incorrect fallthru %i->%i",
2197 e
->src
->index
, e
->dest
->index
);
2198 fatal_insn ("wrong insn in the fallthru edge", insn
);
2205 last_bb_seen
= ENTRY_BLOCK_PTR
;
2207 for (x
= rtx_first
; x
; x
= NEXT_INSN (x
))
2209 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2211 bb
= NOTE_BASIC_BLOCK (x
);
2214 if (bb
!= last_bb_seen
->next_bb
)
2215 internal_error ("basic blocks not laid down consecutively");
2217 curr_bb
= last_bb_seen
= bb
;
2222 switch (GET_CODE (x
))
2229 /* An addr_vec is placed outside any basic block. */
2231 && JUMP_P (NEXT_INSN (x
))
2232 && (GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_DIFF_VEC
2233 || GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_VEC
))
2236 /* But in any case, non-deletable labels can appear anywhere. */
2240 fatal_insn ("insn outside basic block", x
);
2245 && returnjump_p (x
) && ! condjump_p (x
)
2246 && ! (NEXT_INSN (x
) && BARRIER_P (NEXT_INSN (x
))))
2247 fatal_insn ("return not followed by barrier", x
);
2248 if (curr_bb
&& x
== BB_END (curr_bb
))
2252 if (num_bb_notes
!= n_basic_blocks
)
2254 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2255 num_bb_notes
, n_basic_blocks
);
2260 /* Assume that the preceding pass has possibly eliminated jump instructions
2261 or converted the unconditional jumps. Eliminate the edges from CFG.
2262 Return true if any edges are eliminated. */
2265 purge_dead_edges (basic_block bb
)
2268 rtx insn
= BB_END (bb
), note
;
2269 bool purged
= false;
2273 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2274 if (NONJUMP_INSN_P (insn
)
2275 && (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
)))
2279 if (! may_trap_p (PATTERN (insn
))
2280 || ((eqnote
= find_reg_equal_equiv_note (insn
))
2281 && ! may_trap_p (XEXP (eqnote
, 0))))
2282 remove_note (insn
, note
);
2285 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2286 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2288 if (e
->flags
& EDGE_EH
)
2290 if (can_throw_internal (BB_END (bb
)))
2296 else if (e
->flags
& EDGE_ABNORMAL_CALL
)
2298 if (CALL_P (BB_END (bb
))
2299 && (! (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
))
2300 || INTVAL (XEXP (note
, 0)) >= 0))
2313 bb
->flags
|= BB_DIRTY
;
2323 /* We do care only about conditional jumps and simplejumps. */
2324 if (!any_condjump_p (insn
)
2325 && !returnjump_p (insn
)
2326 && !simplejump_p (insn
))
2329 /* Branch probability/prediction notes are defined only for
2330 condjumps. We've possibly turned condjump into simplejump. */
2331 if (simplejump_p (insn
))
2333 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2335 remove_note (insn
, note
);
2336 while ((note
= find_reg_note (insn
, REG_BR_PRED
, NULL
)))
2337 remove_note (insn
, note
);
2340 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2342 /* Avoid abnormal flags to leak from computed jumps turned
2343 into simplejumps. */
2345 e
->flags
&= ~EDGE_ABNORMAL
;
2347 /* See if this edge is one we should keep. */
2348 if ((e
->flags
& EDGE_FALLTHRU
) && any_condjump_p (insn
))
2349 /* A conditional jump can fall through into the next
2350 block, so we should keep the edge. */
2355 else if (e
->dest
!= EXIT_BLOCK_PTR
2356 && BB_HEAD (e
->dest
) == JUMP_LABEL (insn
))
2357 /* If the destination block is the target of the jump,
2363 else if (e
->dest
== EXIT_BLOCK_PTR
&& returnjump_p (insn
))
2364 /* If the destination block is the exit block, and this
2365 instruction is a return, then keep the edge. */
2370 else if ((e
->flags
& EDGE_EH
) && can_throw_internal (insn
))
2371 /* Keep the edges that correspond to exceptions thrown by
2372 this instruction and rematerialize the EDGE_ABNORMAL
2373 flag we just cleared above. */
2375 e
->flags
|= EDGE_ABNORMAL
;
2380 /* We do not need this edge. */
2381 bb
->flags
|= BB_DIRTY
;
2386 if (EDGE_COUNT (bb
->succs
) == 0 || !purged
)
2390 fprintf (dump_file
, "Purged edges from bb %i\n", bb
->index
);
2395 /* Redistribute probabilities. */
2396 if (EDGE_COUNT (bb
->succs
) == 1)
2398 EDGE_SUCC (bb
, 0)->probability
= REG_BR_PROB_BASE
;
2399 EDGE_SUCC (bb
, 0)->count
= bb
->count
;
2403 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2407 b
= BRANCH_EDGE (bb
);
2408 f
= FALLTHRU_EDGE (bb
);
2409 b
->probability
= INTVAL (XEXP (note
, 0));
2410 f
->probability
= REG_BR_PROB_BASE
- b
->probability
;
2411 b
->count
= bb
->count
* b
->probability
/ REG_BR_PROB_BASE
;
2412 f
->count
= bb
->count
* f
->probability
/ REG_BR_PROB_BASE
;
2417 else if (CALL_P (insn
) && SIBLING_CALL_P (insn
))
2419 /* First, there should not be any EH or ABCALL edges resulting
2420 from non-local gotos and the like. If there were, we shouldn't
2421 have created the sibcall in the first place. Second, there
2422 should of course never have been a fallthru edge. */
2423 gcc_assert (EDGE_COUNT (bb
->succs
) == 1);
2424 gcc_assert (EDGE_SUCC (bb
, 0)->flags
== (EDGE_SIBCALL
| EDGE_ABNORMAL
));
2429 /* If we don't see a jump insn, we don't know exactly why the block would
2430 have been broken at this point. Look for a simple, non-fallthru edge,
2431 as these are only created by conditional branches. If we find such an
2432 edge we know that there used to be a jump here and can then safely
2433 remove all non-fallthru edges. */
2435 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2436 if (! (e
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
)))
2445 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); )
2447 if (!(e
->flags
& EDGE_FALLTHRU
))
2449 bb
->flags
|= BB_DIRTY
;
2457 gcc_assert (EDGE_COUNT (bb
->succs
) == 1);
2459 EDGE_SUCC (bb
, 0)->probability
= REG_BR_PROB_BASE
;
2460 EDGE_SUCC (bb
, 0)->count
= bb
->count
;
2463 fprintf (dump_file
, "Purged non-fallthru edges from bb %i\n",
2468 /* Search all basic blocks for potentially dead edges and purge them. Return
2469 true if some edge has been eliminated. */
2472 purge_all_dead_edges (int update_life_p
)
2480 blocks
= sbitmap_alloc (last_basic_block
);
2481 sbitmap_zero (blocks
);
2486 bool purged_here
= purge_dead_edges (bb
);
2488 purged
|= purged_here
;
2489 if (purged_here
&& update_life_p
)
2490 SET_BIT (blocks
, bb
->index
);
2493 if (update_life_p
&& purged
)
2494 update_life_info (blocks
, UPDATE_LIFE_GLOBAL
,
2495 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
2496 | PROP_KILL_DEAD_CODE
);
2499 sbitmap_free (blocks
);
2503 /* Same as split_block but update cfg_layout structures. */
2506 cfg_layout_split_block (basic_block bb
, void *insnp
)
2509 basic_block new_bb
= rtl_split_block (bb
, insn
);
2511 new_bb
->rbi
->footer
= bb
->rbi
->footer
;
2512 bb
->rbi
->footer
= NULL
;
2518 /* Redirect Edge to DEST. */
2520 cfg_layout_redirect_edge_and_branch (edge e
, basic_block dest
)
2522 basic_block src
= e
->src
;
2525 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
2528 if (e
->dest
== dest
)
2531 if (e
->src
!= ENTRY_BLOCK_PTR
2532 && (ret
= try_redirect_by_replacing_jump (e
, dest
, true)))
2534 src
->flags
|= BB_DIRTY
;
2538 if (e
->src
== ENTRY_BLOCK_PTR
2539 && (e
->flags
& EDGE_FALLTHRU
) && !(e
->flags
& EDGE_COMPLEX
))
2542 fprintf (dump_file
, "Redirecting entry edge from bb %i to %i\n",
2543 e
->src
->index
, dest
->index
);
2545 e
->src
->flags
|= BB_DIRTY
;
2546 redirect_edge_succ (e
, dest
);
2550 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2551 in the case the basic block appears to be in sequence. Avoid this
2554 if (e
->flags
& EDGE_FALLTHRU
)
2556 /* Redirect any branch edges unified with the fallthru one. */
2557 if (JUMP_P (BB_END (src
))
2558 && label_is_jump_target_p (BB_HEAD (e
->dest
),
2564 fprintf (dump_file
, "Fallthru edge unified with branch "
2565 "%i->%i redirected to %i\n",
2566 e
->src
->index
, e
->dest
->index
, dest
->index
);
2567 e
->flags
&= ~EDGE_FALLTHRU
;
2568 redirected
= redirect_branch_edge (e
, dest
);
2569 gcc_assert (redirected
);
2570 e
->flags
|= EDGE_FALLTHRU
;
2571 e
->src
->flags
|= BB_DIRTY
;
2574 /* In case we are redirecting fallthru edge to the branch edge
2575 of conditional jump, remove it. */
2576 if (EDGE_COUNT (src
->succs
) == 2)
2578 /* Find the edge that is different from E. */
2579 edge s
= EDGE_SUCC (src
, EDGE_SUCC (src
, 0) == e
);
2582 && any_condjump_p (BB_END (src
))
2583 && onlyjump_p (BB_END (src
)))
2584 delete_insn (BB_END (src
));
2586 ret
= redirect_edge_succ_nodup (e
, dest
);
2588 fprintf (dump_file
, "Fallthru edge %i->%i redirected to %i\n",
2589 e
->src
->index
, e
->dest
->index
, dest
->index
);
2592 ret
= redirect_branch_edge (e
, dest
);
2594 /* We don't want simplejumps in the insn stream during cfglayout. */
2595 gcc_assert (!simplejump_p (BB_END (src
)));
2597 src
->flags
|= BB_DIRTY
;
2601 /* Simple wrapper as we always can redirect fallthru edges. */
2603 cfg_layout_redirect_edge_and_branch_force (edge e
, basic_block dest
)
2605 edge redirected
= cfg_layout_redirect_edge_and_branch (e
, dest
);
2607 gcc_assert (redirected
);
2611 /* Same as delete_basic_block but update cfg_layout structures. */
2614 cfg_layout_delete_block (basic_block bb
)
2616 rtx insn
, next
, prev
= PREV_INSN (BB_HEAD (bb
)), *to
, remaints
;
2618 if (bb
->rbi
->header
)
2620 next
= BB_HEAD (bb
);
2622 NEXT_INSN (prev
) = bb
->rbi
->header
;
2624 set_first_insn (bb
->rbi
->header
);
2625 PREV_INSN (bb
->rbi
->header
) = prev
;
2626 insn
= bb
->rbi
->header
;
2627 while (NEXT_INSN (insn
))
2628 insn
= NEXT_INSN (insn
);
2629 NEXT_INSN (insn
) = next
;
2630 PREV_INSN (next
) = insn
;
2632 next
= NEXT_INSN (BB_END (bb
));
2633 if (bb
->rbi
->footer
)
2635 insn
= bb
->rbi
->footer
;
2638 if (BARRIER_P (insn
))
2640 if (PREV_INSN (insn
))
2641 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
2643 bb
->rbi
->footer
= NEXT_INSN (insn
);
2644 if (NEXT_INSN (insn
))
2645 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
2649 insn
= NEXT_INSN (insn
);
2651 if (bb
->rbi
->footer
)
2654 NEXT_INSN (insn
) = bb
->rbi
->footer
;
2655 PREV_INSN (bb
->rbi
->footer
) = insn
;
2656 while (NEXT_INSN (insn
))
2657 insn
= NEXT_INSN (insn
);
2658 NEXT_INSN (insn
) = next
;
2660 PREV_INSN (next
) = insn
;
2662 set_last_insn (insn
);
2665 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2666 to
= &bb
->next_bb
->rbi
->header
;
2668 to
= &cfg_layout_function_footer
;
2669 rtl_delete_block (bb
);
2672 prev
= NEXT_INSN (prev
);
2674 prev
= get_insns ();
2676 next
= PREV_INSN (next
);
2678 next
= get_last_insn ();
2680 if (next
&& NEXT_INSN (next
) != prev
)
2682 remaints
= unlink_insn_chain (prev
, next
);
2684 while (NEXT_INSN (insn
))
2685 insn
= NEXT_INSN (insn
);
2686 NEXT_INSN (insn
) = *to
;
2688 PREV_INSN (*to
) = insn
;
2693 /* Return true when blocks A and B can be safely merged. */
2695 cfg_layout_can_merge_blocks_p (basic_block a
, basic_block b
)
2697 /* If we are partitioning hot/cold basic blocks, we don't want to
2698 mess up unconditional or indirect jumps that cross between hot
2701 Basic block partitioning may result in some jumps that appear to
2702 be optimizable (or blocks that appear to be mergeable), but which really
2703 must be left untouched (they are required to make it safely across
2704 partition boundaries). See the comments at the top of
2705 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2707 if (flag_reorder_blocks_and_partition
2708 && (find_reg_note (BB_END (a
), REG_CROSSING_JUMP
, NULL_RTX
)
2709 || find_reg_note (BB_END (b
), REG_CROSSING_JUMP
, NULL_RTX
)
2710 || BB_PARTITION (a
) != BB_PARTITION (b
)))
2713 /* There must be exactly one edge in between the blocks. */
2714 return (EDGE_COUNT (a
->succs
) == 1
2715 && EDGE_SUCC (a
, 0)->dest
== b
2716 && EDGE_COUNT (b
->preds
) == 1
2718 /* Must be simple edge. */
2719 && !(EDGE_SUCC (a
, 0)->flags
& EDGE_COMPLEX
)
2720 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
2721 /* If the jump insn has side effects,
2722 we can't kill the edge. */
2723 && (!JUMP_P (BB_END (a
))
2724 || (reload_completed
2725 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
2728 /* Merge block A and B, abort when it is not possible. */
2730 cfg_layout_merge_blocks (basic_block a
, basic_block b
)
2732 #ifdef ENABLE_CHECKING
2733 gcc_assert (cfg_layout_can_merge_blocks_p (a
, b
));
2736 /* If there was a CODE_LABEL beginning B, delete it. */
2737 if (LABEL_P (BB_HEAD (b
)))
2738 delete_insn (BB_HEAD (b
));
2740 /* We should have fallthru edge in a, or we can do dummy redirection to get
2742 if (JUMP_P (BB_END (a
)))
2743 try_redirect_by_replacing_jump (EDGE_SUCC (a
, 0), b
, true);
2744 gcc_assert (!JUMP_P (BB_END (a
)));
2746 /* Possible line number notes should appear in between. */
2749 rtx first
= BB_END (a
), last
;
2751 last
= emit_insn_after_noloc (b
->rbi
->header
, BB_END (a
));
2752 delete_insn_chain (NEXT_INSN (first
), last
);
2753 b
->rbi
->header
= NULL
;
2756 /* In the case basic blocks are not adjacent, move them around. */
2757 if (NEXT_INSN (BB_END (a
)) != BB_HEAD (b
))
2759 rtx first
= unlink_insn_chain (BB_HEAD (b
), BB_END (b
));
2761 emit_insn_after_noloc (first
, BB_END (a
));
2762 /* Skip possible DELETED_LABEL insn. */
2763 if (!NOTE_INSN_BASIC_BLOCK_P (first
))
2764 first
= NEXT_INSN (first
);
2765 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first
));
2767 delete_insn (first
);
2769 /* Otherwise just re-associate the instructions. */
2774 for (insn
= BB_HEAD (b
);
2775 insn
!= NEXT_INSN (BB_END (b
));
2776 insn
= NEXT_INSN (insn
))
2777 set_block_for_insn (insn
, a
);
2779 /* Skip possible DELETED_LABEL insn. */
2780 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
2781 insn
= NEXT_INSN (insn
);
2782 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
2784 BB_END (a
) = BB_END (b
);
2788 /* Possible tablejumps and barriers should appear after the block. */
2791 if (!a
->rbi
->footer
)
2792 a
->rbi
->footer
= b
->rbi
->footer
;
2795 rtx last
= a
->rbi
->footer
;
2797 while (NEXT_INSN (last
))
2798 last
= NEXT_INSN (last
);
2799 NEXT_INSN (last
) = b
->rbi
->footer
;
2800 PREV_INSN (b
->rbi
->footer
) = last
;
2802 b
->rbi
->footer
= NULL
;
2806 fprintf (dump_file
, "Merged blocks %d and %d.\n",
2807 a
->index
, b
->index
);
2813 cfg_layout_split_edge (edge e
)
2816 basic_block new_bb
=
2817 create_basic_block (e
->src
!= ENTRY_BLOCK_PTR
2818 ? NEXT_INSN (BB_END (e
->src
)) : get_insns (),
2821 /* ??? This info is likely going to be out of date very soon, but we must
2822 create it to avoid getting an ICE later. */
2823 if (e
->dest
->global_live_at_start
)
2825 new_bb
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
2826 new_bb
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
2827 COPY_REG_SET (new_bb
->global_live_at_start
,
2828 e
->dest
->global_live_at_start
);
2829 COPY_REG_SET (new_bb
->global_live_at_end
,
2830 e
->dest
->global_live_at_start
);
2833 new_e
= make_edge (new_bb
, e
->dest
, EDGE_FALLTHRU
);
2834 redirect_edge_and_branch_force (e
, new_bb
);
2839 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2842 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED
)
2846 /* Return 1 if BB ends with a call, possibly followed by some
2847 instructions that must stay with the call, 0 otherwise. */
2850 rtl_block_ends_with_call_p (basic_block bb
)
2852 rtx insn
= BB_END (bb
);
2854 while (!CALL_P (insn
)
2855 && insn
!= BB_HEAD (bb
)
2856 && keep_with_call_p (insn
))
2857 insn
= PREV_INSN (insn
);
2858 return (CALL_P (insn
));
2861 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2864 rtl_block_ends_with_condjump_p (basic_block bb
)
2866 return any_condjump_p (BB_END (bb
));
2869 /* Return true if we need to add fake edge to exit.
2870 Helper function for rtl_flow_call_edges_add. */
2873 need_fake_edge_p (rtx insn
)
2879 && !SIBLING_CALL_P (insn
)
2880 && !find_reg_note (insn
, REG_NORETURN
, NULL
)
2881 && !find_reg_note (insn
, REG_ALWAYS_RETURN
, NULL
)
2882 && !CONST_OR_PURE_CALL_P (insn
)))
2885 return ((GET_CODE (PATTERN (insn
)) == ASM_OPERANDS
2886 && MEM_VOLATILE_P (PATTERN (insn
)))
2887 || (GET_CODE (PATTERN (insn
)) == PARALLEL
2888 && asm_noperands (insn
) != -1
2889 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn
), 0, 0)))
2890 || GET_CODE (PATTERN (insn
)) == ASM_INPUT
);
2893 /* Add fake edges to the function exit for any non constant and non noreturn
2894 calls, volatile inline assembly in the bitmap of blocks specified by
2895 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2898 The goal is to expose cases in which entering a basic block does not imply
2899 that all subsequent instructions must be executed. */
2902 rtl_flow_call_edges_add (sbitmap blocks
)
2905 int blocks_split
= 0;
2906 int last_bb
= last_basic_block
;
2907 bool check_last_block
= false;
2909 if (n_basic_blocks
== 0)
2913 check_last_block
= true;
2915 check_last_block
= TEST_BIT (blocks
, EXIT_BLOCK_PTR
->prev_bb
->index
);
2917 /* In the last basic block, before epilogue generation, there will be
2918 a fallthru edge to EXIT. Special care is required if the last insn
2919 of the last basic block is a call because make_edge folds duplicate
2920 edges, which would result in the fallthru edge also being marked
2921 fake, which would result in the fallthru edge being removed by
2922 remove_fake_edges, which would result in an invalid CFG.
2924 Moreover, we can't elide the outgoing fake edge, since the block
2925 profiler needs to take this into account in order to solve the minimal
2926 spanning tree in the case that the call doesn't return.
2928 Handle this by adding a dummy instruction in a new last basic block. */
2929 if (check_last_block
)
2931 basic_block bb
= EXIT_BLOCK_PTR
->prev_bb
;
2932 rtx insn
= BB_END (bb
);
2934 /* Back up past insns that must be kept in the same block as a call. */
2935 while (insn
!= BB_HEAD (bb
)
2936 && keep_with_call_p (insn
))
2937 insn
= PREV_INSN (insn
);
2939 if (need_fake_edge_p (insn
))
2943 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
2946 insert_insn_on_edge (gen_rtx_USE (VOIDmode
, const0_rtx
), e
);
2947 commit_edge_insertions ();
2952 /* Now add fake edges to the function exit for any non constant
2953 calls since there is no way that we can determine if they will
2956 for (i
= 0; i
< last_bb
; i
++)
2958 basic_block bb
= BASIC_BLOCK (i
);
2965 if (blocks
&& !TEST_BIT (blocks
, i
))
2968 for (insn
= BB_END (bb
); ; insn
= prev_insn
)
2970 prev_insn
= PREV_INSN (insn
);
2971 if (need_fake_edge_p (insn
))
2974 rtx split_at_insn
= insn
;
2976 /* Don't split the block between a call and an insn that should
2977 remain in the same block as the call. */
2979 while (split_at_insn
!= BB_END (bb
)
2980 && keep_with_call_p (NEXT_INSN (split_at_insn
)))
2981 split_at_insn
= NEXT_INSN (split_at_insn
);
2983 /* The handling above of the final block before the epilogue
2984 should be enough to verify that there is no edge to the exit
2985 block in CFG already. Calling make_edge in such case would
2986 cause us to mark that edge as fake and remove it later. */
2988 #ifdef ENABLE_CHECKING
2989 if (split_at_insn
== BB_END (bb
))
2991 e
= find_edge (bb
, EXIT_BLOCK_PTR
);
2992 gcc_assert (e
== NULL
);
2996 /* Note that the following may create a new basic block
2997 and renumber the existing basic blocks. */
2998 if (split_at_insn
!= BB_END (bb
))
3000 e
= split_block (bb
, split_at_insn
);
3005 make_edge (bb
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
3008 if (insn
== BB_HEAD (bb
))
3014 verify_flow_info ();
3016 return blocks_split
;
3019 /* Implementation of CFG manipulation for linearized RTL. */
3020 struct cfg_hooks rtl_cfg_hooks
= {
3022 rtl_verify_flow_info
,
3024 rtl_create_basic_block
,
3025 rtl_redirect_edge_and_branch
,
3026 rtl_redirect_edge_and_branch_force
,
3029 rtl_move_block_after
,
3030 rtl_can_merge_blocks
, /* can_merge_blocks_p */
3034 NULL
, /* can_duplicate_block_p */
3035 NULL
, /* duplicate_block */
3037 rtl_make_forwarder_block
,
3038 rtl_tidy_fallthru_edge
,
3039 rtl_block_ends_with_call_p
,
3040 rtl_block_ends_with_condjump_p
,
3041 rtl_flow_call_edges_add
,
3042 NULL
, /* execute_on_growing_pred */
3043 NULL
/* execute_on_shrinking_pred */
3046 /* Implementation of CFG manipulation for cfg layout RTL, where
3047 basic block connected via fallthru edges does not have to be adjacent.
3048 This representation will hopefully become the default one in future
3049 version of the compiler. */
3051 /* We do not want to declare these functions in a header file, since they
3052 should only be used through the cfghooks interface, and we do not want to
3053 move them here since it would require also moving quite a lot of related
3055 extern bool cfg_layout_can_duplicate_bb_p (basic_block
);
3056 extern basic_block
cfg_layout_duplicate_bb (basic_block
);
3058 struct cfg_hooks cfg_layout_rtl_cfg_hooks
= {
3060 rtl_verify_flow_info_1
,
3062 cfg_layout_create_basic_block
,
3063 cfg_layout_redirect_edge_and_branch
,
3064 cfg_layout_redirect_edge_and_branch_force
,
3065 cfg_layout_delete_block
,
3066 cfg_layout_split_block
,
3067 rtl_move_block_after
,
3068 cfg_layout_can_merge_blocks_p
,
3069 cfg_layout_merge_blocks
,
3072 cfg_layout_can_duplicate_bb_p
,
3073 cfg_layout_duplicate_bb
,
3074 cfg_layout_split_edge
,
3075 rtl_make_forwarder_block
,
3077 rtl_block_ends_with_call_p
,
3078 rtl_block_ends_with_condjump_p
,
3079 rtl_flow_call_edges_add
,
3080 NULL
, /* execute_on_growing_pred */
3081 NULL
/* execute_on_shrinking_pred */