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 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"
60 /* Stubs in case we don't have a return insn. */
63 #define gen_return() NULL_RTX
66 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
67 /* ??? Should probably be using LABEL_NUSES instead. It would take a
68 bit of surgery to be able to use or co-opt the routines in jump. */
70 rtx tail_recursion_label_list
;
72 static int can_delete_note_p (rtx
);
73 static int can_delete_label_p (rtx
);
74 static void commit_one_edge_insertion (edge
, int);
75 static rtx
last_loop_beg_note (rtx
);
76 static bool back_edge_of_syntactic_loop_p (basic_block
, basic_block
);
77 basic_block
force_nonfallthru_and_redirect (edge
, basic_block
);
78 static basic_block
rtl_split_edge (edge
);
79 static int rtl_verify_flow_info (void);
80 static edge
cfg_layout_split_block (basic_block
, void *);
81 static bool cfg_layout_redirect_edge_and_branch (edge
, basic_block
);
82 static basic_block
cfg_layout_redirect_edge_and_branch_force (edge
, basic_block
);
83 static void cfg_layout_delete_block (basic_block
);
84 static void rtl_delete_block (basic_block
);
85 static basic_block
rtl_redirect_edge_and_branch_force (edge
, basic_block
);
86 static bool rtl_redirect_edge_and_branch (edge
, basic_block
);
87 static edge
rtl_split_block (basic_block
, void *);
88 static void rtl_dump_bb (basic_block
, FILE *);
89 static int rtl_verify_flow_info_1 (void);
90 static void mark_killed_regs (rtx
, rtx
, void *);
92 /* Return true if NOTE is not one of the ones that must be kept paired,
93 so that we may simply delete it. */
96 can_delete_note_p (rtx note
)
98 return (NOTE_LINE_NUMBER (note
) == NOTE_INSN_DELETED
99 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_BASIC_BLOCK
100 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_PREDICTION
);
103 /* True if a given label can be deleted. */
106 can_delete_label_p (rtx label
)
108 return (!LABEL_PRESERVE_P (label
)
109 /* User declared labels must be preserved. */
110 && LABEL_NAME (label
) == 0
111 && !in_expr_list_p (forced_labels
, label
)
112 && !in_expr_list_p (label_value_list
, label
));
115 /* Delete INSN by patching it out. Return the next insn. */
118 delete_insn (rtx insn
)
120 rtx next
= NEXT_INSN (insn
);
122 bool really_delete
= true;
124 if (GET_CODE (insn
) == CODE_LABEL
)
126 /* Some labels can't be directly removed from the INSN chain, as they
127 might be references via variables, constant pool etc.
128 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
129 if (! can_delete_label_p (insn
))
131 const char *name
= LABEL_NAME (insn
);
133 really_delete
= false;
134 PUT_CODE (insn
, NOTE
);
135 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
136 NOTE_SOURCE_FILE (insn
) = name
;
139 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
144 /* If this insn has already been deleted, something is very wrong. */
145 if (INSN_DELETED_P (insn
))
148 INSN_DELETED_P (insn
) = 1;
151 /* If deleting a jump, decrement the use count of the label. Deleting
152 the label itself should happen in the normal course of block merging. */
153 if (GET_CODE (insn
) == JUMP_INSN
155 && GET_CODE (JUMP_LABEL (insn
)) == CODE_LABEL
)
156 LABEL_NUSES (JUMP_LABEL (insn
))--;
158 /* Also if deleting an insn that references a label. */
161 while ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)) != NULL_RTX
162 && GET_CODE (XEXP (note
, 0)) == CODE_LABEL
)
164 LABEL_NUSES (XEXP (note
, 0))--;
165 remove_note (insn
, note
);
169 if (GET_CODE (insn
) == JUMP_INSN
170 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
171 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
173 rtx pat
= PATTERN (insn
);
174 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
175 int len
= XVECLEN (pat
, diff_vec_p
);
178 for (i
= 0; i
< len
; i
++)
180 rtx label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
182 /* When deleting code in bulk (e.g. removing many unreachable
183 blocks) we can delete a label that's a target of the vector
184 before deleting the vector itself. */
185 if (GET_CODE (label
) != NOTE
)
186 LABEL_NUSES (label
)--;
193 /* Like delete_insn but also purge dead edges from BB. */
195 delete_insn_and_edges (rtx insn
)
201 && BLOCK_FOR_INSN (insn
)
202 && BB_END (BLOCK_FOR_INSN (insn
)) == insn
)
204 x
= delete_insn (insn
);
206 purge_dead_edges (BLOCK_FOR_INSN (insn
));
210 /* Unlink a chain of insns between START and FINISH, leaving notes
211 that must be paired. */
214 delete_insn_chain (rtx start
, rtx finish
)
218 /* Unchain the insns one by one. It would be quicker to delete all of these
219 with a single unchaining, rather than one at a time, but we need to keep
223 next
= NEXT_INSN (start
);
224 if (GET_CODE (start
) == NOTE
&& !can_delete_note_p (start
))
227 next
= delete_insn (start
);
235 /* Like delete_insn but also purge dead edges from BB. */
237 delete_insn_chain_and_edges (rtx first
, rtx last
)
242 && BLOCK_FOR_INSN (last
)
243 && BB_END (BLOCK_FOR_INSN (last
)) == last
)
245 delete_insn_chain (first
, last
);
247 purge_dead_edges (BLOCK_FOR_INSN (last
));
250 /* Create a new basic block consisting of the instructions between HEAD and END
251 inclusive. This function is designed to allow fast BB construction - reuses
252 the note and basic block struct in BB_NOTE, if any and do not grow
253 BASIC_BLOCK chain and should be used directly only by CFG construction code.
254 END can be NULL in to create new empty basic block before HEAD. Both END
255 and HEAD can be NULL to create basic block at the end of INSN chain.
256 AFTER is the basic block we should be put after. */
259 create_basic_block_structure (rtx head
, rtx end
, rtx bb_note
, basic_block after
)
264 && ! RTX_INTEGRATED_P (bb_note
)
265 && (bb
= NOTE_BASIC_BLOCK (bb_note
)) != NULL
268 /* If we found an existing note, thread it back onto the chain. */
272 if (GET_CODE (head
) == CODE_LABEL
)
276 after
= PREV_INSN (head
);
280 if (after
!= bb_note
&& NEXT_INSN (after
) != bb_note
)
281 reorder_insns_nobb (bb_note
, bb_note
, after
);
285 /* Otherwise we must create a note and a basic block structure. */
291 = emit_note_after (NOTE_INSN_BASIC_BLOCK
, get_last_insn ());
292 else if (GET_CODE (head
) == CODE_LABEL
&& end
)
294 bb_note
= emit_note_after (NOTE_INSN_BASIC_BLOCK
, head
);
300 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
, head
);
306 NOTE_BASIC_BLOCK (bb_note
) = bb
;
309 /* Always include the bb note in the block. */
310 if (NEXT_INSN (end
) == bb_note
)
315 bb
->index
= last_basic_block
++;
317 link_block (bb
, after
);
318 BASIC_BLOCK (bb
->index
) = bb
;
319 update_bb_for_insn (bb
);
321 /* Tag the block so that we know it has been used when considering
322 other basic block notes. */
328 /* Create new basic block consisting of instructions in between HEAD and END
329 and place it to the BB chain after block AFTER. END can be NULL in to
330 create new empty basic block before HEAD. Both END and HEAD can be NULL to
331 create basic block at the end of INSN chain. */
334 rtl_create_basic_block (void *headp
, void *endp
, basic_block after
)
336 rtx head
= headp
, end
= endp
;
339 /* Place the new block just after the end. */
340 VARRAY_GROW (basic_block_info
, last_basic_block
+1);
344 bb
= create_basic_block_structure (head
, end
, NULL
, after
);
350 cfg_layout_create_basic_block (void *head
, void *end
, basic_block after
)
352 basic_block newbb
= rtl_create_basic_block (head
, end
, after
);
354 cfg_layout_initialize_rbi (newbb
);
358 /* Delete the insns in a (non-live) block. We physically delete every
359 non-deleted-note insn, and update the flow graph appropriately.
361 Return nonzero if we deleted an exception handler. */
363 /* ??? Preserving all such notes strikes me as wrong. It would be nice
364 to post-process the stream to remove empty blocks, loops, ranges, etc. */
367 rtl_delete_block (basic_block b
)
371 /* If the head of this block is a CODE_LABEL, then it might be the
372 label for an exception handler which can't be reached.
374 We need to remove the label from the exception_handler_label list
375 and remove the associated NOTE_INSN_EH_REGION_BEG and
376 NOTE_INSN_EH_REGION_END notes. */
378 /* Get rid of all NOTE_INSN_PREDICTIONs and NOTE_INSN_LOOP_CONTs
379 hanging before the block. */
381 for (insn
= PREV_INSN (BB_HEAD (b
)); insn
; insn
= PREV_INSN (insn
))
383 if (GET_CODE (insn
) != NOTE
)
385 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_PREDICTION
386 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
)
387 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
392 never_reached_warning (insn
, BB_END (b
));
394 if (GET_CODE (insn
) == CODE_LABEL
)
395 maybe_remove_eh_handler (insn
);
397 /* Include any jump table following the basic block. */
399 if (tablejump_p (end
, NULL
, &tmp
))
402 /* Include any barrier that may follow the basic block. */
403 tmp
= next_nonnote_insn (end
);
404 if (tmp
&& GET_CODE (tmp
) == BARRIER
)
407 /* Selectively delete the entire chain. */
409 delete_insn_chain (insn
, end
);
411 /* Remove the edges into and out of this block. Note that there may
412 indeed be edges in, if we are removing an unreachable loop. */
413 while (b
->pred
!= NULL
)
414 remove_edge (b
->pred
);
415 while (b
->succ
!= NULL
)
416 remove_edge (b
->succ
);
421 /* Remove the basic block from the array. */
425 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
428 compute_bb_for_insn (void)
434 rtx end
= BB_END (bb
);
437 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
439 BLOCK_FOR_INSN (insn
) = bb
;
446 /* Release the basic_block_for_insn array. */
449 free_bb_for_insn (void)
452 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
453 if (GET_CODE (insn
) != BARRIER
)
454 BLOCK_FOR_INSN (insn
) = NULL
;
457 /* Update insns block within BB. */
460 update_bb_for_insn (basic_block bb
)
464 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
466 if (GET_CODE (insn
) != BARRIER
)
467 set_block_for_insn (insn
, bb
);
468 if (insn
== BB_END (bb
))
473 /* Split a block BB after insn INSN creating a new fallthru edge.
474 Return the new edge. Note that to keep other parts of the compiler happy,
475 this function renumbers all the basic blocks so that the new
476 one has a number one greater than the block split. */
479 rtl_split_block (basic_block bb
, void *insnp
)
486 /* There is no point splitting the block after its end. */
487 if (BB_END (bb
) == insn
)
490 /* Create the new basic block. */
491 new_bb
= create_basic_block (NEXT_INSN (insn
), BB_END (bb
), bb
);
492 new_bb
->count
= bb
->count
;
493 new_bb
->frequency
= bb
->frequency
;
494 new_bb
->loop_depth
= bb
->loop_depth
;
497 /* Redirect the outgoing edges. */
498 new_bb
->succ
= bb
->succ
;
500 for (e
= new_bb
->succ
; e
; e
= e
->succ_next
)
503 new_edge
= make_single_succ_edge (bb
, new_bb
, EDGE_FALLTHRU
);
505 if (bb
->global_live_at_start
)
507 new_bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
508 new_bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
509 COPY_REG_SET (new_bb
->global_live_at_end
, bb
->global_live_at_end
);
511 /* We now have to calculate which registers are live at the end
512 of the split basic block and at the start of the new basic
513 block. Start with those registers that are known to be live
514 at the end of the original basic block and get
515 propagate_block to determine which registers are live. */
516 COPY_REG_SET (new_bb
->global_live_at_start
, bb
->global_live_at_end
);
517 propagate_block (new_bb
, new_bb
->global_live_at_start
, NULL
, NULL
, 0);
518 COPY_REG_SET (bb
->global_live_at_end
,
519 new_bb
->global_live_at_start
);
520 #ifdef HAVE_conditional_execution
521 /* In the presence of conditional execution we are not able to update
522 liveness precisely. */
523 if (reload_completed
)
525 bb
->flags
|= BB_DIRTY
;
526 new_bb
->flags
|= BB_DIRTY
;
534 /* Assume that the code of basic block B has been merged into A.
535 Do corresponding CFG updates: redirect edges accordingly etc. */
537 update_cfg_after_block_merging (basic_block a
, basic_block b
)
541 /* Normally there should only be one successor of A and that is B, but
542 partway though the merge of blocks for conditional_execution we'll
543 be merging a TEST block with THEN and ELSE successors. Free the
544 whole lot of them and hope the caller knows what they're doing. */
546 remove_edge (a
->succ
);
548 /* Adjust the edges out of B for the new owner. */
549 for (e
= b
->succ
; e
; e
= e
->succ_next
)
552 a
->flags
|= b
->flags
;
554 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
555 b
->pred
= b
->succ
= NULL
;
556 a
->global_live_at_end
= b
->global_live_at_end
;
561 /* Blocks A and B are to be merged into a single block A. The insns
562 are already contiguous. */
565 rtl_merge_blocks (basic_block a
, basic_block b
)
567 rtx b_head
= BB_HEAD (b
), b_end
= BB_END (b
), a_end
= BB_END (a
);
568 rtx del_first
= NULL_RTX
, del_last
= NULL_RTX
;
571 /* If there was a CODE_LABEL beginning B, delete it. */
572 if (GET_CODE (b_head
) == CODE_LABEL
)
574 /* Detect basic blocks with nothing but a label. This can happen
575 in particular at the end of a function. */
579 del_first
= del_last
= b_head
;
580 b_head
= NEXT_INSN (b_head
);
583 /* Delete the basic block note and handle blocks containing just that
585 if (NOTE_INSN_BASIC_BLOCK_P (b_head
))
593 b_head
= NEXT_INSN (b_head
);
596 /* If there was a jump out of A, delete it. */
597 if (GET_CODE (a_end
) == JUMP_INSN
)
601 for (prev
= PREV_INSN (a_end
); ; prev
= PREV_INSN (prev
))
602 if (GET_CODE (prev
) != NOTE
603 || NOTE_LINE_NUMBER (prev
) == NOTE_INSN_BASIC_BLOCK
604 || prev
== BB_HEAD (a
))
610 /* If this was a conditional jump, we need to also delete
611 the insn that set cc0. */
612 if (only_sets_cc0_p (prev
))
616 prev
= prev_nonnote_insn (prev
);
623 a_end
= PREV_INSN (del_first
);
625 else if (GET_CODE (NEXT_INSN (a_end
)) == BARRIER
)
626 del_first
= NEXT_INSN (a_end
);
628 update_cfg_after_block_merging (a
, b
);
630 /* Delete everything marked above as well as crap that might be
631 hanging out between the two blocks. */
632 delete_insn_chain (del_first
, del_last
);
634 /* Reassociate the insns of B with A. */
639 for (x
= a_end
; x
!= b_end
; x
= NEXT_INSN (x
))
640 set_block_for_insn (x
, a
);
642 set_block_for_insn (b_end
, a
);
650 /* Return true when block A and B can be merged. */
652 rtl_can_merge_blocks (basic_block a
,basic_block b
)
654 /* There must be exactly one edge in between the blocks. */
655 return (a
->succ
&& !a
->succ
->succ_next
&& a
->succ
->dest
== b
656 && !b
->pred
->pred_next
&& a
!= b
657 /* Must be simple edge. */
658 && !(a
->succ
->flags
& EDGE_COMPLEX
)
660 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
661 /* If the jump insn has side effects,
662 we can't kill the edge. */
663 && (GET_CODE (BB_END (a
)) != JUMP_INSN
665 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
668 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
672 block_label (basic_block block
)
674 if (block
== EXIT_BLOCK_PTR
)
677 if (GET_CODE (BB_HEAD (block
)) != CODE_LABEL
)
679 BB_HEAD (block
) = emit_label_before (gen_label_rtx (), BB_HEAD (block
));
682 return BB_HEAD (block
);
685 /* Attempt to perform edge redirection by replacing possibly complex jump
686 instruction by unconditional jump or removing jump completely. This can
687 apply only if all edges now point to the same block. The parameters and
688 return values are equivalent to redirect_edge_and_branch. */
691 try_redirect_by_replacing_jump (edge e
, basic_block target
, bool in_cfglayout
)
693 basic_block src
= e
->src
;
694 rtx insn
= BB_END (src
), kill_from
;
699 /* Verify that all targets will be TARGET. */
700 for (tmp
= src
->succ
; tmp
; tmp
= tmp
->succ_next
)
701 if (tmp
->dest
!= target
&& tmp
!= e
)
704 if (tmp
|| !onlyjump_p (insn
))
706 if ((!optimize
|| flow2_completed
) && tablejump_p (insn
, NULL
, NULL
))
709 /* Avoid removing branch with side effects. */
710 set
= single_set (insn
);
711 if (!set
|| side_effects_p (set
))
714 /* In case we zap a conditional jump, we'll need to kill
715 the cc0 setter too. */
718 if (reg_mentioned_p (cc0_rtx
, PATTERN (insn
)))
719 kill_from
= PREV_INSN (insn
);
722 /* See if we can create the fallthru edge. */
723 if (in_cfglayout
|| can_fallthru (src
, target
))
726 fprintf (rtl_dump_file
, "Removing jump %i.\n", INSN_UID (insn
));
729 /* Selectively unlink whole insn chain. */
732 rtx insn
= src
->rbi
->footer
;
734 delete_insn_chain (kill_from
, BB_END (src
));
736 /* Remove barriers but keep jumptables. */
739 if (GET_CODE (insn
) == BARRIER
)
741 if (PREV_INSN (insn
))
742 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
744 src
->rbi
->footer
= NEXT_INSN (insn
);
745 if (NEXT_INSN (insn
))
746 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
748 if (GET_CODE (insn
) == CODE_LABEL
)
750 insn
= NEXT_INSN (insn
);
754 delete_insn_chain (kill_from
, PREV_INSN (BB_HEAD (target
)));
757 /* If this already is simplejump, redirect it. */
758 else if (simplejump_p (insn
))
760 if (e
->dest
== target
)
763 fprintf (rtl_dump_file
, "Redirecting jump %i from %i to %i.\n",
764 INSN_UID (insn
), e
->dest
->index
, target
->index
);
765 if (!redirect_jump (insn
, block_label (target
), 0))
767 if (target
== EXIT_BLOCK_PTR
)
773 /* Cannot do anything for target exit block. */
774 else if (target
== EXIT_BLOCK_PTR
)
777 /* Or replace possibly complicated jump insn by simple jump insn. */
780 rtx target_label
= block_label (target
);
781 rtx barrier
, label
, table
;
783 emit_jump_insn_after (gen_jump (target_label
), insn
);
784 JUMP_LABEL (BB_END (src
)) = target_label
;
785 LABEL_NUSES (target_label
)++;
787 fprintf (rtl_dump_file
, "Replacing insn %i by jump %i\n",
788 INSN_UID (insn
), INSN_UID (BB_END (src
)));
791 delete_insn_chain (kill_from
, insn
);
793 /* Recognize a tablejump that we are converting to a
794 simple jump and remove its associated CODE_LABEL
795 and ADDR_VEC or ADDR_DIFF_VEC. */
796 if (! reload_completed
&& tablejump_p (insn
, &label
, &table
))
797 delete_insn_chain (label
, table
);
799 barrier
= next_nonnote_insn (BB_END (src
));
800 if (!barrier
|| GET_CODE (barrier
) != BARRIER
)
801 emit_barrier_after (BB_END (src
));
804 if (barrier
!= NEXT_INSN (BB_END (src
)))
806 /* Move the jump before barrier so that the notes
807 which originally were or were created before jump table are
808 inside the basic block. */
809 rtx new_insn
= BB_END (src
);
812 for (tmp
= NEXT_INSN (BB_END (src
)); tmp
!= barrier
;
813 tmp
= NEXT_INSN (tmp
))
814 set_block_for_insn (tmp
, src
);
816 NEXT_INSN (PREV_INSN (new_insn
)) = NEXT_INSN (new_insn
);
817 PREV_INSN (NEXT_INSN (new_insn
)) = PREV_INSN (new_insn
);
819 NEXT_INSN (new_insn
) = barrier
;
820 NEXT_INSN (PREV_INSN (barrier
)) = new_insn
;
822 PREV_INSN (new_insn
) = PREV_INSN (barrier
);
823 PREV_INSN (barrier
) = new_insn
;
828 /* Keep only one edge out and set proper flags. */
829 while (src
->succ
->succ_next
)
830 remove_edge (src
->succ
);
833 e
->flags
= EDGE_FALLTHRU
;
837 e
->probability
= REG_BR_PROB_BASE
;
838 e
->count
= src
->count
;
840 /* We don't want a block to end on a line-number note since that has
841 the potential of changing the code between -g and not -g. */
842 while (GET_CODE (BB_END (e
->src
)) == NOTE
843 && NOTE_LINE_NUMBER (BB_END (e
->src
)) >= 0)
844 delete_insn (BB_END (e
->src
));
846 if (e
->dest
!= target
)
847 redirect_edge_succ (e
, target
);
852 /* Return last loop_beg note appearing after INSN, before start of next
853 basic block. Return INSN if there are no such notes.
855 When emitting jump to redirect a fallthru edge, it should always appear
856 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
857 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
861 last_loop_beg_note (rtx insn
)
865 for (insn
= NEXT_INSN (insn
); insn
&& GET_CODE (insn
) == NOTE
866 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
;
867 insn
= NEXT_INSN (insn
))
868 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
874 /* Redirect edge representing branch of (un)conditional jump or tablejump. */
876 redirect_branch_edge (edge e
, basic_block target
)
879 rtx old_label
= BB_HEAD (e
->dest
);
880 basic_block src
= e
->src
;
881 rtx insn
= BB_END (src
);
883 /* We can only redirect non-fallthru edges of jump insn. */
884 if (e
->flags
& EDGE_FALLTHRU
)
886 else if (GET_CODE (insn
) != JUMP_INSN
)
889 /* Recognize a tablejump and adjust all matching cases. */
890 if (tablejump_p (insn
, NULL
, &tmp
))
894 rtx new_label
= block_label (target
);
896 if (target
== EXIT_BLOCK_PTR
)
898 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
899 vec
= XVEC (PATTERN (tmp
), 0);
901 vec
= XVEC (PATTERN (tmp
), 1);
903 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
904 if (XEXP (RTVEC_ELT (vec
, j
), 0) == old_label
)
906 RTVEC_ELT (vec
, j
) = gen_rtx_LABEL_REF (Pmode
, new_label
);
907 --LABEL_NUSES (old_label
);
908 ++LABEL_NUSES (new_label
);
911 /* Handle casesi dispatch insns. */
912 if ((tmp
= single_set (insn
)) != NULL
913 && SET_DEST (tmp
) == pc_rtx
914 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
915 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
916 && XEXP (XEXP (SET_SRC (tmp
), 2), 0) == old_label
)
918 XEXP (SET_SRC (tmp
), 2) = gen_rtx_LABEL_REF (VOIDmode
,
920 --LABEL_NUSES (old_label
);
921 ++LABEL_NUSES (new_label
);
926 /* ?? We may play the games with moving the named labels from
927 one basic block to the other in case only one computed_jump is
929 if (computed_jump_p (insn
)
930 /* A return instruction can't be redirected. */
931 || returnjump_p (insn
))
934 /* If the insn doesn't go where we think, we're confused. */
935 if (JUMP_LABEL (insn
) != old_label
)
938 /* If the substitution doesn't succeed, die. This can happen
939 if the back end emitted unrecognizable instructions or if
940 target is exit block on some arches. */
941 if (!redirect_jump (insn
, block_label (target
), 0))
943 if (target
== EXIT_BLOCK_PTR
)
950 fprintf (rtl_dump_file
, "Edge %i->%i redirected to %i\n",
951 e
->src
->index
, e
->dest
->index
, target
->index
);
953 if (e
->dest
!= target
)
954 redirect_edge_succ_nodup (e
, target
);
958 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
959 expense of adding new instructions or reordering basic blocks.
961 Function can be also called with edge destination equivalent to the TARGET.
962 Then it should try the simplifications and do nothing if none is possible.
964 Return true if transformation succeeded. We still return false in case E
965 already destinated TARGET and we didn't managed to simplify instruction
969 rtl_redirect_edge_and_branch (edge e
, basic_block target
)
971 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
974 if (try_redirect_by_replacing_jump (e
, target
, false))
977 /* Do this fast path late, as we want above code to simplify for cases
978 where called on single edge leaving basic block containing nontrivial
980 else if (e
->dest
== target
)
982 else if (!redirect_branch_edge (e
, target
))
988 /* Like force_nonfallthru below, but additionally performs redirection
989 Used by redirect_edge_and_branch_force. */
992 force_nonfallthru_and_redirect (edge e
, basic_block target
)
994 basic_block jump_block
, new_bb
= NULL
, src
= e
->src
;
997 int abnormal_edge_flags
= 0;
999 /* In the case the last instruction is conditional jump to the next
1000 instruction, first redirect the jump itself and then continue
1001 by creating a basic block afterwards to redirect fallthru edge. */
1002 if (e
->src
!= ENTRY_BLOCK_PTR
&& e
->dest
!= EXIT_BLOCK_PTR
1003 && any_condjump_p (BB_END (e
->src
))
1004 /* When called from cfglayout, fallthru edges do not
1005 necessarily go to the next block. */
1006 && e
->src
->next_bb
== e
->dest
1007 && JUMP_LABEL (BB_END (e
->src
)) == BB_HEAD (e
->dest
))
1010 edge b
= unchecked_make_edge (e
->src
, target
, 0);
1012 if (!redirect_jump (BB_END (e
->src
), block_label (target
), 0))
1014 note
= find_reg_note (BB_END (e
->src
), REG_BR_PROB
, NULL_RTX
);
1017 int prob
= INTVAL (XEXP (note
, 0));
1019 b
->probability
= prob
;
1020 b
->count
= e
->count
* prob
/ REG_BR_PROB_BASE
;
1021 e
->probability
-= e
->probability
;
1022 e
->count
-= b
->count
;
1023 if (e
->probability
< 0)
1030 if (e
->flags
& EDGE_ABNORMAL
)
1032 /* Irritating special case - fallthru edge to the same block as abnormal
1034 We can't redirect abnormal edge, but we still can split the fallthru
1035 one and create separate abnormal edge to original destination.
1036 This allows bb-reorder to make such edge non-fallthru. */
1037 if (e
->dest
!= target
)
1039 abnormal_edge_flags
= e
->flags
& ~(EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
);
1040 e
->flags
&= EDGE_FALLTHRU
| EDGE_CAN_FALLTHRU
;
1042 else if (!(e
->flags
& EDGE_FALLTHRU
))
1044 else if (e
->src
== ENTRY_BLOCK_PTR
)
1046 /* We can't redirect the entry block. Create an empty block at the
1047 start of the function which we use to add the new jump. */
1049 basic_block bb
= create_basic_block (BB_HEAD (e
->dest
), NULL
, ENTRY_BLOCK_PTR
);
1051 /* Change the existing edge's source to be the new block, and add
1052 a new edge from the entry block to the new block. */
1054 for (pe1
= &ENTRY_BLOCK_PTR
->succ
; *pe1
; pe1
= &(*pe1
)->succ_next
)
1057 *pe1
= e
->succ_next
;
1062 make_single_succ_edge (ENTRY_BLOCK_PTR
, bb
, EDGE_FALLTHRU
);
1065 if (e
->src
->succ
->succ_next
|| abnormal_edge_flags
)
1067 /* Create the new structures. */
1069 /* If the old block ended with a tablejump, skip its table
1070 by searching forward from there. Otherwise start searching
1071 forward from the last instruction of the old block. */
1072 if (!tablejump_p (BB_END (e
->src
), NULL
, ¬e
))
1073 note
= BB_END (e
->src
);
1075 /* Position the new block correctly relative to loop notes. */
1076 note
= last_loop_beg_note (note
);
1077 note
= NEXT_INSN (note
);
1079 jump_block
= create_basic_block (note
, NULL
, e
->src
);
1080 jump_block
->count
= e
->count
;
1081 jump_block
->frequency
= EDGE_FREQUENCY (e
);
1082 jump_block
->loop_depth
= target
->loop_depth
;
1084 if (target
->global_live_at_start
)
1086 jump_block
->global_live_at_start
1087 = OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1088 jump_block
->global_live_at_end
1089 = OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1090 COPY_REG_SET (jump_block
->global_live_at_start
,
1091 target
->global_live_at_start
);
1092 COPY_REG_SET (jump_block
->global_live_at_end
,
1093 target
->global_live_at_start
);
1097 new_edge
= make_edge (e
->src
, jump_block
, EDGE_FALLTHRU
);
1098 new_edge
->probability
= e
->probability
;
1099 new_edge
->count
= e
->count
;
1101 /* Redirect old edge. */
1102 redirect_edge_pred (e
, jump_block
);
1103 e
->probability
= REG_BR_PROB_BASE
;
1105 new_bb
= jump_block
;
1108 jump_block
= e
->src
;
1110 e
->flags
&= ~EDGE_FALLTHRU
;
1111 if (target
== EXIT_BLOCK_PTR
)
1114 emit_jump_insn_after (gen_return (), BB_END (jump_block
));
1120 rtx label
= block_label (target
);
1121 emit_jump_insn_after (gen_jump (label
), BB_END (jump_block
));
1122 JUMP_LABEL (BB_END (jump_block
)) = label
;
1123 LABEL_NUSES (label
)++;
1126 emit_barrier_after (BB_END (jump_block
));
1127 redirect_edge_succ_nodup (e
, target
);
1129 if (abnormal_edge_flags
)
1130 make_edge (src
, target
, abnormal_edge_flags
);
1135 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1136 (and possibly create new basic block) to make edge non-fallthru.
1137 Return newly created BB or NULL if none. */
1140 force_nonfallthru (edge e
)
1142 return force_nonfallthru_and_redirect (e
, e
->dest
);
1145 /* Redirect edge even at the expense of creating new jump insn or
1146 basic block. Return new basic block if created, NULL otherwise.
1147 Abort if conversion is impossible. */
1150 rtl_redirect_edge_and_branch_force (edge e
, basic_block target
)
1152 if (redirect_edge_and_branch (e
, target
)
1153 || e
->dest
== target
)
1156 /* In case the edge redirection failed, try to force it to be non-fallthru
1157 and redirect newly created simplejump. */
1158 return force_nonfallthru_and_redirect (e
, target
);
1161 /* The given edge should potentially be a fallthru edge. If that is in
1162 fact true, delete the jump and barriers that are in the way. */
1165 tidy_fallthru_edge (edge e
, basic_block b
, basic_block c
)
1169 /* ??? In a late-running flow pass, other folks may have deleted basic
1170 blocks by nopping out blocks, leaving multiple BARRIERs between here
1171 and the target label. They ought to be chastized and fixed.
1173 We can also wind up with a sequence of undeletable labels between
1174 one block and the next.
1176 So search through a sequence of barriers, labels, and notes for
1177 the head of block C and assert that we really do fall through. */
1179 for (q
= NEXT_INSN (BB_END (b
)); q
!= BB_HEAD (c
); q
= NEXT_INSN (q
))
1183 /* Remove what will soon cease being the jump insn from the source block.
1184 If block B consisted only of this single jump, turn it into a deleted
1187 if (GET_CODE (q
) == JUMP_INSN
1189 && (any_uncondjump_p (q
)
1190 || (b
->succ
== e
&& e
->succ_next
== NULL
)))
1193 /* If this was a conditional jump, we need to also delete
1194 the insn that set cc0. */
1195 if (any_condjump_p (q
) && only_sets_cc0_p (PREV_INSN (q
)))
1201 /* We don't want a block to end on a line-number note since that has
1202 the potential of changing the code between -g and not -g. */
1203 while (GET_CODE (q
) == NOTE
&& NOTE_LINE_NUMBER (q
) >= 0)
1207 /* Selectively unlink the sequence. */
1208 if (q
!= PREV_INSN (BB_HEAD (c
)))
1209 delete_insn_chain (NEXT_INSN (q
), PREV_INSN (BB_HEAD (c
)));
1211 e
->flags
|= EDGE_FALLTHRU
;
1214 /* Fix up edges that now fall through, or rather should now fall through
1215 but previously required a jump around now deleted blocks. Simplify
1216 the search by only examining blocks numerically adjacent, since this
1217 is how find_basic_blocks created them. */
1220 tidy_fallthru_edges (void)
1224 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
1227 FOR_BB_BETWEEN (b
, ENTRY_BLOCK_PTR
->next_bb
, EXIT_BLOCK_PTR
->prev_bb
, next_bb
)
1233 /* We care about simple conditional or unconditional jumps with
1236 If we had a conditional branch to the next instruction when
1237 find_basic_blocks was called, then there will only be one
1238 out edge for the block which ended with the conditional
1239 branch (since we do not create duplicate edges).
1241 Furthermore, the edge will be marked as a fallthru because we
1242 merge the flags for the duplicate edges. So we do not want to
1243 check that the edge is not a FALLTHRU edge. */
1245 if ((s
= b
->succ
) != NULL
1246 && ! (s
->flags
& EDGE_COMPLEX
)
1247 && s
->succ_next
== NULL
1249 /* If the jump insn has side effects, we can't tidy the edge. */
1250 && (GET_CODE (BB_END (b
)) != JUMP_INSN
1251 || onlyjump_p (BB_END (b
))))
1252 tidy_fallthru_edge (s
, b
, c
);
1256 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1257 is back edge of syntactic loop. */
1260 back_edge_of_syntactic_loop_p (basic_block bb1
, basic_block bb2
)
1269 /* ??? Could we guarantee that bb indices are monotone, so that we could
1270 just compare them? */
1271 for (bb
= bb1
; bb
&& bb
!= bb2
; bb
= bb
->next_bb
)
1277 for (insn
= BB_END (bb1
); insn
!= BB_HEAD (bb2
) && count
>= 0;
1278 insn
= NEXT_INSN (insn
))
1279 if (GET_CODE (insn
) == NOTE
)
1281 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
1283 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
1290 /* Split a (typically critical) edge. Return the new block.
1291 Abort on abnormal edges.
1293 ??? The code generally expects to be called on critical edges.
1294 The case of a block ending in an unconditional jump to a
1295 block with multiple predecessors is not handled optimally. */
1298 rtl_split_edge (edge edge_in
)
1303 /* Abnormal edges cannot be split. */
1304 if ((edge_in
->flags
& EDGE_ABNORMAL
) != 0)
1307 /* We are going to place the new block in front of edge destination.
1308 Avoid existence of fallthru predecessors. */
1309 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1313 for (e
= edge_in
->dest
->pred
; e
; e
= e
->pred_next
)
1314 if (e
->flags
& EDGE_FALLTHRU
)
1318 force_nonfallthru (e
);
1321 /* Create the basic block note.
1323 Where we place the note can have a noticeable impact on the generated
1324 code. Consider this cfg:
1334 If we need to insert an insn on the edge from block 0 to block 1,
1335 we want to ensure the instructions we insert are outside of any
1336 loop notes that physically sit between block 0 and block 1. Otherwise
1337 we confuse the loop optimizer into thinking the loop is a phony. */
1339 if (edge_in
->dest
!= EXIT_BLOCK_PTR
1340 && PREV_INSN (BB_HEAD (edge_in
->dest
))
1341 && GET_CODE (PREV_INSN (BB_HEAD (edge_in
->dest
))) == NOTE
1342 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in
->dest
)))
1343 == NOTE_INSN_LOOP_BEG
)
1344 && !back_edge_of_syntactic_loop_p (edge_in
->dest
, edge_in
->src
))
1345 before
= PREV_INSN (BB_HEAD (edge_in
->dest
));
1346 else if (edge_in
->dest
!= EXIT_BLOCK_PTR
)
1347 before
= BB_HEAD (edge_in
->dest
);
1351 bb
= create_basic_block (before
, NULL
, edge_in
->dest
->prev_bb
);
1352 bb
->count
= edge_in
->count
;
1353 bb
->frequency
= EDGE_FREQUENCY (edge_in
);
1355 /* ??? This info is likely going to be out of date very soon. */
1356 if (edge_in
->dest
->global_live_at_start
)
1358 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1359 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1360 COPY_REG_SET (bb
->global_live_at_start
,
1361 edge_in
->dest
->global_live_at_start
);
1362 COPY_REG_SET (bb
->global_live_at_end
,
1363 edge_in
->dest
->global_live_at_start
);
1366 make_single_succ_edge (bb
, edge_in
->dest
, EDGE_FALLTHRU
);
1368 /* For non-fallthru edges, we must adjust the predecessor's
1369 jump instruction to target our new block. */
1370 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1372 if (!redirect_edge_and_branch (edge_in
, bb
))
1376 redirect_edge_succ (edge_in
, bb
);
1381 /* Queue instructions for insertion on an edge between two basic blocks.
1382 The new instructions and basic blocks (if any) will not appear in the
1383 CFG until commit_edge_insertions is called. */
1386 insert_insn_on_edge (rtx pattern
, edge e
)
1388 /* We cannot insert instructions on an abnormal critical edge.
1389 It will be easier to find the culprit if we die now. */
1390 if ((e
->flags
& EDGE_ABNORMAL
) && EDGE_CRITICAL_P (e
))
1393 if (e
->insns
== NULL_RTX
)
1396 push_to_sequence (e
->insns
);
1398 emit_insn (pattern
);
1400 e
->insns
= get_insns ();
1404 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1405 registers that are killed by the store. */
1407 mark_killed_regs (rtx reg
, rtx set ATTRIBUTE_UNUSED
, void *data
)
1409 regset killed
= data
;
1412 if (GET_CODE (reg
) == SUBREG
)
1413 reg
= SUBREG_REG (reg
);
1416 regno
= REGNO (reg
);
1417 if (regno
>= FIRST_PSEUDO_REGISTER
)
1418 SET_REGNO_REG_SET (killed
, regno
);
1421 for (i
= 0; i
< (int) HARD_REGNO_NREGS (regno
, GET_MODE (reg
)); i
++)
1422 SET_REGNO_REG_SET (killed
, regno
+ i
);
1426 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1427 it checks whether this will not clobber the registers that are live on the
1428 edge (i.e. it requires liveness information to be up-to-date) and if there
1429 are some, then it tries to save and restore them. Returns true if
1432 safe_insert_insn_on_edge (rtx insn
, edge e
)
1435 regset_head killed_head
;
1436 regset killed
= INITIALIZE_REG_SET (killed_head
);
1437 rtx save_regs
= NULL_RTX
;
1438 int regno
, noccmode
;
1439 enum machine_mode mode
;
1441 #ifdef AVOID_CCMODE_COPIES
1447 for (x
= insn
; x
; x
= NEXT_INSN (x
))
1449 note_stores (PATTERN (x
), mark_killed_regs
, killed
);
1450 bitmap_operation (killed
, killed
, e
->dest
->global_live_at_start
,
1453 EXECUTE_IF_SET_IN_REG_SET (killed
, 0, regno
,
1455 mode
= regno
< FIRST_PSEUDO_REGISTER
1456 ? reg_raw_mode
[regno
]
1457 : GET_MODE (regno_reg_rtx
[regno
]);
1458 if (mode
== VOIDmode
)
1461 if (noccmode
&& mode
== CCmode
)
1464 save_regs
= alloc_EXPR_LIST (0,
1467 gen_raw_REG (mode
, regno
)),
1476 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1478 from
= XEXP (XEXP (x
, 0), 1);
1479 to
= XEXP (XEXP (x
, 0), 0);
1480 emit_move_insn (to
, from
);
1483 for (x
= save_regs
; x
; x
= XEXP (x
, 1))
1485 from
= XEXP (XEXP (x
, 0), 0);
1486 to
= XEXP (XEXP (x
, 0), 1);
1487 emit_move_insn (to
, from
);
1489 insn
= get_insns ();
1491 free_EXPR_LIST_list (&save_regs
);
1493 insert_insn_on_edge (insn
, e
);
1495 FREE_REG_SET (killed
);
1499 /* Update the CFG for the instructions queued on edge E. */
1502 commit_one_edge_insertion (edge e
, int watch_calls
)
1504 rtx before
= NULL_RTX
, after
= NULL_RTX
, insns
, tmp
, last
;
1505 basic_block bb
= NULL
;
1507 /* Pull the insns off the edge now since the edge might go away. */
1509 e
->insns
= NULL_RTX
;
1511 /* Special case -- avoid inserting code between call and storing
1512 its return value. */
1513 if (watch_calls
&& (e
->flags
& EDGE_FALLTHRU
) && !e
->dest
->pred
->pred_next
1514 && e
->src
!= ENTRY_BLOCK_PTR
1515 && GET_CODE (BB_END (e
->src
)) == CALL_INSN
)
1517 rtx next
= next_nonnote_insn (BB_END (e
->src
));
1519 after
= BB_HEAD (e
->dest
);
1520 /* The first insn after the call may be a stack pop, skip it. */
1522 && keep_with_call_p (next
))
1525 next
= next_nonnote_insn (next
);
1529 if (!before
&& !after
)
1531 /* Figure out where to put these things. If the destination has
1532 one predecessor, insert there. Except for the exit block. */
1533 if (e
->dest
->pred
->pred_next
== NULL
&& e
->dest
!= EXIT_BLOCK_PTR
)
1537 /* Get the location correct wrt a code label, and "nice" wrt
1538 a basic block note, and before everything else. */
1540 if (GET_CODE (tmp
) == CODE_LABEL
)
1541 tmp
= NEXT_INSN (tmp
);
1542 if (NOTE_INSN_BASIC_BLOCK_P (tmp
))
1543 tmp
= NEXT_INSN (tmp
);
1544 if (tmp
== BB_HEAD (bb
))
1547 after
= PREV_INSN (tmp
);
1549 after
= get_last_insn ();
1552 /* If the source has one successor and the edge is not abnormal,
1553 insert there. Except for the entry block. */
1554 else if ((e
->flags
& EDGE_ABNORMAL
) == 0
1555 && e
->src
->succ
->succ_next
== NULL
1556 && e
->src
!= ENTRY_BLOCK_PTR
)
1560 /* It is possible to have a non-simple jump here. Consider a target
1561 where some forms of unconditional jumps clobber a register. This
1562 happens on the fr30 for example.
1564 We know this block has a single successor, so we can just emit
1565 the queued insns before the jump. */
1566 if (GET_CODE (BB_END (bb
)) == JUMP_INSN
)
1567 for (before
= BB_END (bb
);
1568 GET_CODE (PREV_INSN (before
)) == NOTE
1569 && NOTE_LINE_NUMBER (PREV_INSN (before
)) ==
1570 NOTE_INSN_LOOP_BEG
; before
= PREV_INSN (before
))
1574 /* We'd better be fallthru, or we've lost track of what's what. */
1575 if ((e
->flags
& EDGE_FALLTHRU
) == 0)
1578 after
= BB_END (bb
);
1581 /* Otherwise we must split the edge. */
1584 bb
= split_edge (e
);
1585 after
= BB_END (bb
);
1589 /* Now that we've found the spot, do the insertion. */
1593 emit_insn_before (insns
, before
);
1594 last
= prev_nonnote_insn (before
);
1597 last
= emit_insn_after (insns
, after
);
1599 if (returnjump_p (last
))
1601 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1602 This is not currently a problem because this only happens
1603 for the (single) epilogue, which already has a fallthru edge
1607 if (e
->dest
!= EXIT_BLOCK_PTR
1608 || e
->succ_next
!= NULL
|| (e
->flags
& EDGE_FALLTHRU
) == 0)
1611 e
->flags
&= ~EDGE_FALLTHRU
;
1612 emit_barrier_after (last
);
1615 delete_insn (before
);
1617 else if (GET_CODE (last
) == JUMP_INSN
)
1620 /* Mark the basic block for find_sub_basic_blocks. */
1624 /* Update the CFG for all queued instructions. */
1627 commit_edge_insertions (void)
1631 bool changed
= false;
1633 #ifdef ENABLE_CHECKING
1634 verify_flow_info ();
1637 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1641 for (e
= bb
->succ
; e
; e
= next
)
1643 next
= e
->succ_next
;
1647 commit_one_edge_insertion (e
, false);
1655 blocks
= sbitmap_alloc (last_basic_block
);
1656 sbitmap_zero (blocks
);
1660 SET_BIT (blocks
, bb
->index
);
1661 /* Check for forgotten bb->aux values before commit_edge_insertions
1663 if (bb
->aux
!= &bb
->aux
)
1667 find_many_sub_basic_blocks (blocks
);
1668 sbitmap_free (blocks
);
1671 /* Update the CFG for all queued instructions, taking special care of inserting
1672 code on edges between call and storing its return value. */
1675 commit_edge_insertions_watch_calls (void)
1679 bool changed
= false;
1681 #ifdef ENABLE_CHECKING
1682 verify_flow_info ();
1685 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, EXIT_BLOCK_PTR
, next_bb
)
1689 for (e
= bb
->succ
; e
; e
= next
)
1691 next
= e
->succ_next
;
1695 commit_one_edge_insertion (e
, true);
1703 blocks
= sbitmap_alloc (last_basic_block
);
1704 sbitmap_zero (blocks
);
1708 SET_BIT (blocks
, bb
->index
);
1709 /* Check for forgotten bb->aux values before commit_edge_insertions
1711 if (bb
->aux
!= &bb
->aux
)
1715 find_many_sub_basic_blocks (blocks
);
1716 sbitmap_free (blocks
);
1719 /* Print out one basic block with live information at start and end. */
1722 rtl_dump_bb (basic_block bb
, FILE *outf
)
1727 fputs (";; Registers live at start:", outf
);
1728 dump_regset (bb
->global_live_at_start
, outf
);
1731 for (insn
= BB_HEAD (bb
), last
= NEXT_INSN (BB_END (bb
)); insn
!= last
;
1732 insn
= NEXT_INSN (insn
))
1733 print_rtl_single (outf
, insn
);
1735 fputs (";; Registers live at end:", outf
);
1736 dump_regset (bb
->global_live_at_end
, outf
);
1740 /* Like print_rtl, but also print out live information for the start of each
1744 print_rtl_with_bb (FILE *outf
, rtx rtx_first
)
1749 fprintf (outf
, "(nil)\n");
1752 enum bb_state
{ NOT_IN_BB
, IN_ONE_BB
, IN_MULTIPLE_BB
};
1753 int max_uid
= get_max_uid ();
1754 basic_block
*start
= xcalloc (max_uid
, sizeof (basic_block
));
1755 basic_block
*end
= xcalloc (max_uid
, sizeof (basic_block
));
1756 enum bb_state
*in_bb_p
= xcalloc (max_uid
, sizeof (enum bb_state
));
1760 FOR_EACH_BB_REVERSE (bb
)
1764 start
[INSN_UID (BB_HEAD (bb
))] = bb
;
1765 end
[INSN_UID (BB_END (bb
))] = bb
;
1766 for (x
= BB_HEAD (bb
); x
!= NULL_RTX
; x
= NEXT_INSN (x
))
1768 enum bb_state state
= IN_MULTIPLE_BB
;
1770 if (in_bb_p
[INSN_UID (x
)] == NOT_IN_BB
)
1772 in_bb_p
[INSN_UID (x
)] = state
;
1774 if (x
== BB_END (bb
))
1779 for (tmp_rtx
= rtx_first
; NULL
!= tmp_rtx
; tmp_rtx
= NEXT_INSN (tmp_rtx
))
1783 if ((bb
= start
[INSN_UID (tmp_rtx
)]) != NULL
)
1785 fprintf (outf
, ";; Start of basic block %d, registers live:",
1787 dump_regset (bb
->global_live_at_start
, outf
);
1791 if (in_bb_p
[INSN_UID (tmp_rtx
)] == NOT_IN_BB
1792 && GET_CODE (tmp_rtx
) != NOTE
1793 && GET_CODE (tmp_rtx
) != BARRIER
)
1794 fprintf (outf
, ";; Insn is not within a basic block\n");
1795 else if (in_bb_p
[INSN_UID (tmp_rtx
)] == IN_MULTIPLE_BB
)
1796 fprintf (outf
, ";; Insn is in multiple basic blocks\n");
1798 did_output
= print_rtl_single (outf
, tmp_rtx
);
1800 if ((bb
= end
[INSN_UID (tmp_rtx
)]) != NULL
)
1802 fprintf (outf
, ";; End of basic block %d, registers live:\n",
1804 dump_regset (bb
->global_live_at_end
, outf
);
1817 if (current_function_epilogue_delay_list
!= 0)
1819 fprintf (outf
, "\n;; Insns in epilogue delay list:\n\n");
1820 for (tmp_rtx
= current_function_epilogue_delay_list
; tmp_rtx
!= 0;
1821 tmp_rtx
= XEXP (tmp_rtx
, 1))
1822 print_rtl_single (outf
, XEXP (tmp_rtx
, 0));
1827 update_br_prob_note (basic_block bb
)
1830 if (GET_CODE (BB_END (bb
)) != JUMP_INSN
)
1832 note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
);
1833 if (!note
|| INTVAL (XEXP (note
, 0)) == BRANCH_EDGE (bb
)->probability
)
1835 XEXP (note
, 0) = GEN_INT (BRANCH_EDGE (bb
)->probability
);
1838 /* Verify the CFG and RTL consistency common for both underlying RTL and
1841 Currently it does following checks:
1843 - test head/end pointers
1844 - overlapping of basic blocks
1845 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1846 - tails of basic blocks (ensure that boundary is necessary)
1847 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1848 and NOTE_INSN_BASIC_BLOCK
1850 In future it can be extended check a lot of other stuff as well
1851 (reachability of basic blocks, life information, etc. etc.). */
1853 rtl_verify_flow_info_1 (void)
1855 const int max_uid
= get_max_uid ();
1856 rtx last_head
= get_last_insn ();
1857 basic_block
*bb_info
;
1860 basic_block bb
, last_bb_seen
;
1862 bb_info
= xcalloc (max_uid
, sizeof (basic_block
));
1864 /* Check bb chain & numbers. */
1865 last_bb_seen
= ENTRY_BLOCK_PTR
;
1867 FOR_EACH_BB_REVERSE (bb
)
1869 rtx head
= BB_HEAD (bb
);
1870 rtx end
= BB_END (bb
);
1872 /* Verify the end of the basic block is in the INSN chain. */
1873 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1879 error ("end insn %d for block %d not found in the insn stream",
1880 INSN_UID (end
), bb
->index
);
1884 /* Work backwards from the end to the head of the basic block
1885 to verify the head is in the RTL chain. */
1886 for (; x
!= NULL_RTX
; x
= PREV_INSN (x
))
1888 /* While walking over the insn chain, verify insns appear
1889 in only one basic block and initialize the BB_INFO array
1890 used by other passes. */
1891 if (bb_info
[INSN_UID (x
)] != NULL
)
1893 error ("insn %d is in multiple basic blocks (%d and %d)",
1894 INSN_UID (x
), bb
->index
, bb_info
[INSN_UID (x
)]->index
);
1898 bb_info
[INSN_UID (x
)] = bb
;
1905 error ("head insn %d for block %d not found in the insn stream",
1906 INSN_UID (head
), bb
->index
);
1913 /* Now check the basic blocks (boundaries etc.) */
1914 FOR_EACH_BB_REVERSE (bb
)
1916 int n_fallthru
= 0, n_eh
= 0, n_call
= 0, n_abnormal
= 0, n_branch
= 0;
1917 edge e
, fallthru
= NULL
;
1920 if (INSN_P (BB_END (bb
))
1921 && (note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
))
1922 && bb
->succ
&& bb
->succ
->succ_next
1923 && any_condjump_p (BB_END (bb
)))
1925 if (INTVAL (XEXP (note
, 0)) != BRANCH_EDGE (bb
)->probability
)
1927 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1928 INTVAL (XEXP (note
, 0)), BRANCH_EDGE (bb
)->probability
);
1932 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1934 if (e
->flags
& EDGE_FALLTHRU
)
1935 n_fallthru
++, fallthru
= e
;
1937 if ((e
->flags
& ~(EDGE_DFS_BACK
1939 | EDGE_IRREDUCIBLE_LOOP
1940 | EDGE_LOOP_EXIT
)) == 0)
1943 if (e
->flags
& EDGE_ABNORMAL_CALL
)
1946 if (e
->flags
& EDGE_EH
)
1948 else if (e
->flags
& EDGE_ABNORMAL
)
1952 if (n_eh
&& GET_CODE (PATTERN (BB_END (bb
))) != RESX
1953 && !find_reg_note (BB_END (bb
), REG_EH_REGION
, NULL_RTX
))
1955 error ("Missing REG_EH_REGION note in the end of bb %i", bb
->index
);
1959 && (GET_CODE (BB_END (bb
)) != JUMP_INSN
1960 || (n_branch
> 1 && (any_uncondjump_p (BB_END (bb
))
1961 || any_condjump_p (BB_END (bb
))))))
1963 error ("Too many outgoing branch edges from bb %i", bb
->index
);
1966 if (n_fallthru
&& any_uncondjump_p (BB_END (bb
)))
1968 error ("Fallthru edge after unconditional jump %i", bb
->index
);
1971 if (n_branch
!= 1 && any_uncondjump_p (BB_END (bb
)))
1973 error ("Wrong amount of branch edges after unconditional jump %i", bb
->index
);
1976 if (n_branch
!= 1 && any_condjump_p (BB_END (bb
))
1977 && JUMP_LABEL (BB_END (bb
)) != BB_HEAD (fallthru
->dest
))
1979 error ("Wrong amount of branch edges after conditional jump %i", bb
->index
);
1982 if (n_call
&& GET_CODE (BB_END (bb
)) != CALL_INSN
)
1984 error ("Call edges for non-call insn in bb %i", bb
->index
);
1988 && (GET_CODE (BB_END (bb
)) != CALL_INSN
&& n_call
!= n_abnormal
)
1989 && (GET_CODE (BB_END (bb
)) != JUMP_INSN
1990 || any_condjump_p (BB_END (bb
))
1991 || any_uncondjump_p (BB_END (bb
))))
1993 error ("Abnormal edges for no purpose in bb %i", bb
->index
);
1997 for (x
= BB_HEAD (bb
); x
!= NEXT_INSN (BB_END (bb
)); x
= NEXT_INSN (x
))
1998 if (BLOCK_FOR_INSN (x
) != bb
)
2001 if (! BLOCK_FOR_INSN (x
))
2003 ("insn %d inside basic block %d but block_for_insn is NULL",
2004 INSN_UID (x
), bb
->index
);
2007 ("insn %d inside basic block %d but block_for_insn is %i",
2008 INSN_UID (x
), bb
->index
, BLOCK_FOR_INSN (x
)->index
);
2013 /* OK pointers are correct. Now check the header of basic
2014 block. It ought to contain optional CODE_LABEL followed
2015 by NOTE_BASIC_BLOCK. */
2017 if (GET_CODE (x
) == CODE_LABEL
)
2019 if (BB_END (bb
) == x
)
2021 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2029 if (!NOTE_INSN_BASIC_BLOCK_P (x
) || NOTE_BASIC_BLOCK (x
) != bb
)
2031 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2036 if (BB_END (bb
) == x
)
2037 /* Do checks for empty blocks her. e */
2040 for (x
= NEXT_INSN (x
); x
; x
= NEXT_INSN (x
))
2042 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2044 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2045 INSN_UID (x
), bb
->index
);
2049 if (x
== BB_END (bb
))
2052 if (control_flow_insn_p (x
))
2054 error ("in basic block %d:", bb
->index
);
2055 fatal_insn ("flow control insn inside a basic block", x
);
2065 /* Verify the CFG and RTL consistency common for both underlying RTL and
2068 Currently it does following checks:
2069 - all checks of rtl_verify_flow_info_1
2070 - check that all insns are in the basic blocks
2071 (except the switch handling code, barriers and notes)
2072 - check that all returns are followed by barriers
2073 - check that all fallthru edge points to the adjacent blocks. */
2075 rtl_verify_flow_info (void)
2078 int err
= rtl_verify_flow_info_1 ();
2081 const rtx rtx_first
= get_insns ();
2082 basic_block last_bb_seen
= ENTRY_BLOCK_PTR
, curr_bb
= NULL
;
2084 FOR_EACH_BB_REVERSE (bb
)
2087 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
2088 if (e
->flags
& EDGE_FALLTHRU
)
2094 /* Ensure existence of barrier in BB with no fallthru edges. */
2095 for (insn
= BB_END (bb
); !insn
|| GET_CODE (insn
) != BARRIER
;
2096 insn
= NEXT_INSN (insn
))
2098 || (GET_CODE (insn
) == NOTE
2099 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BASIC_BLOCK
))
2101 error ("missing barrier after block %i", bb
->index
);
2106 else if (e
->src
!= ENTRY_BLOCK_PTR
2107 && e
->dest
!= EXIT_BLOCK_PTR
)
2111 if (e
->src
->next_bb
!= e
->dest
)
2114 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2115 e
->src
->index
, e
->dest
->index
);
2119 for (insn
= NEXT_INSN (BB_END (e
->src
)); insn
!= BB_HEAD (e
->dest
);
2120 insn
= NEXT_INSN (insn
))
2121 if (GET_CODE (insn
) == BARRIER
2122 #ifndef CASE_DROPS_THROUGH
2125 || (INSN_P (insn
) && ! JUMP_TABLE_DATA_P (insn
))
2129 error ("verify_flow_info: Incorrect fallthru %i->%i",
2130 e
->src
->index
, e
->dest
->index
);
2131 fatal_insn ("wrong insn in the fallthru edge", insn
);
2138 last_bb_seen
= ENTRY_BLOCK_PTR
;
2140 for (x
= rtx_first
; x
; x
= NEXT_INSN (x
))
2142 if (NOTE_INSN_BASIC_BLOCK_P (x
))
2144 bb
= NOTE_BASIC_BLOCK (x
);
2147 if (bb
!= last_bb_seen
->next_bb
)
2148 internal_error ("basic blocks not laid down consecutively");
2150 curr_bb
= last_bb_seen
= bb
;
2155 switch (GET_CODE (x
))
2162 /* An addr_vec is placed outside any block block. */
2164 && GET_CODE (NEXT_INSN (x
)) == JUMP_INSN
2165 && (GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_DIFF_VEC
2166 || GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_VEC
))
2169 /* But in any case, non-deletable labels can appear anywhere. */
2173 fatal_insn ("insn outside basic block", x
);
2178 && GET_CODE (x
) == JUMP_INSN
2179 && returnjump_p (x
) && ! condjump_p (x
)
2180 && ! (NEXT_INSN (x
) && GET_CODE (NEXT_INSN (x
)) == BARRIER
))
2181 fatal_insn ("return not followed by barrier", x
);
2182 if (curr_bb
&& x
== BB_END (curr_bb
))
2186 if (num_bb_notes
!= n_basic_blocks
)
2188 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2189 num_bb_notes
, n_basic_blocks
);
2194 /* Assume that the preceding pass has possibly eliminated jump instructions
2195 or converted the unconditional jumps. Eliminate the edges from CFG.
2196 Return true if any edges are eliminated. */
2199 purge_dead_edges (basic_block bb
)
2202 rtx insn
= BB_END (bb
), note
;
2203 bool purged
= false;
2205 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2206 if (GET_CODE (insn
) == INSN
2207 && (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
)))
2211 if (! may_trap_p (PATTERN (insn
))
2212 || ((eqnote
= find_reg_equal_equiv_note (insn
))
2213 && ! may_trap_p (XEXP (eqnote
, 0))))
2214 remove_note (insn
, note
);
2217 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2218 for (e
= bb
->succ
; e
; e
= next
)
2220 next
= e
->succ_next
;
2221 if (e
->flags
& EDGE_EH
)
2223 if (can_throw_internal (BB_END (bb
)))
2226 else if (e
->flags
& EDGE_ABNORMAL_CALL
)
2228 if (GET_CODE (BB_END (bb
)) == CALL_INSN
2229 && (! (note
= find_reg_note (insn
, REG_EH_REGION
, NULL
))
2230 || INTVAL (XEXP (note
, 0)) >= 0))
2237 bb
->flags
|= BB_DIRTY
;
2241 if (GET_CODE (insn
) == JUMP_INSN
)
2246 /* We do care only about conditional jumps and simplejumps. */
2247 if (!any_condjump_p (insn
)
2248 && !returnjump_p (insn
)
2249 && !simplejump_p (insn
))
2252 /* Branch probability/prediction notes are defined only for
2253 condjumps. We've possibly turned condjump into simplejump. */
2254 if (simplejump_p (insn
))
2256 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2258 remove_note (insn
, note
);
2259 while ((note
= find_reg_note (insn
, REG_BR_PRED
, NULL
)))
2260 remove_note (insn
, note
);
2263 for (e
= bb
->succ
; e
; e
= next
)
2265 next
= e
->succ_next
;
2267 /* Avoid abnormal flags to leak from computed jumps turned
2268 into simplejumps. */
2270 e
->flags
&= ~EDGE_ABNORMAL
;
2272 /* See if this edge is one we should keep. */
2273 if ((e
->flags
& EDGE_FALLTHRU
) && any_condjump_p (insn
))
2274 /* A conditional jump can fall through into the next
2275 block, so we should keep the edge. */
2277 else if (e
->dest
!= EXIT_BLOCK_PTR
2278 && BB_HEAD (e
->dest
) == JUMP_LABEL (insn
))
2279 /* If the destination block is the target of the jump,
2282 else if (e
->dest
== EXIT_BLOCK_PTR
&& returnjump_p (insn
))
2283 /* If the destination block is the exit block, and this
2284 instruction is a return, then keep the edge. */
2286 else if ((e
->flags
& EDGE_EH
) && can_throw_internal (insn
))
2287 /* Keep the edges that correspond to exceptions thrown by
2288 this instruction and rematerialize the EDGE_ABNORMAL
2289 flag we just cleared above. */
2291 e
->flags
|= EDGE_ABNORMAL
;
2295 /* We do not need this edge. */
2296 bb
->flags
|= BB_DIRTY
;
2301 if (!bb
->succ
|| !purged
)
2305 fprintf (rtl_dump_file
, "Purged edges from bb %i\n", bb
->index
);
2310 /* Redistribute probabilities. */
2311 if (!bb
->succ
->succ_next
)
2313 bb
->succ
->probability
= REG_BR_PROB_BASE
;
2314 bb
->succ
->count
= bb
->count
;
2318 note
= find_reg_note (insn
, REG_BR_PROB
, NULL
);
2322 b
= BRANCH_EDGE (bb
);
2323 f
= FALLTHRU_EDGE (bb
);
2324 b
->probability
= INTVAL (XEXP (note
, 0));
2325 f
->probability
= REG_BR_PROB_BASE
- b
->probability
;
2326 b
->count
= bb
->count
* b
->probability
/ REG_BR_PROB_BASE
;
2327 f
->count
= bb
->count
* f
->probability
/ REG_BR_PROB_BASE
;
2332 else if (GET_CODE (insn
) == CALL_INSN
&& SIBLING_CALL_P (insn
))
2334 /* First, there should not be any EH or ABCALL edges resulting
2335 from non-local gotos and the like. If there were, we shouldn't
2336 have created the sibcall in the first place. Second, there
2337 should of course never have been a fallthru edge. */
2338 if (!bb
->succ
|| bb
->succ
->succ_next
)
2340 if (bb
->succ
->flags
!= (EDGE_SIBCALL
| EDGE_ABNORMAL
))
2346 /* If we don't see a jump insn, we don't know exactly why the block would
2347 have been broken at this point. Look for a simple, non-fallthru edge,
2348 as these are only created by conditional branches. If we find such an
2349 edge we know that there used to be a jump here and can then safely
2350 remove all non-fallthru edges. */
2351 for (e
= bb
->succ
; e
&& (e
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
));
2358 for (e
= bb
->succ
; e
; e
= next
)
2360 next
= e
->succ_next
;
2361 if (!(e
->flags
& EDGE_FALLTHRU
))
2363 bb
->flags
|= BB_DIRTY
;
2369 if (!bb
->succ
|| bb
->succ
->succ_next
)
2372 bb
->succ
->probability
= REG_BR_PROB_BASE
;
2373 bb
->succ
->count
= bb
->count
;
2376 fprintf (rtl_dump_file
, "Purged non-fallthru edges from bb %i\n",
2381 /* Search all basic blocks for potentially dead edges and purge them. Return
2382 true if some edge has been eliminated. */
2385 purge_all_dead_edges (int update_life_p
)
2393 blocks
= sbitmap_alloc (last_basic_block
);
2394 sbitmap_zero (blocks
);
2399 bool purged_here
= purge_dead_edges (bb
);
2401 purged
|= purged_here
;
2402 if (purged_here
&& update_life_p
)
2403 SET_BIT (blocks
, bb
->index
);
2406 if (update_life_p
&& purged
)
2407 update_life_info (blocks
, UPDATE_LIFE_GLOBAL
,
2408 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
2409 | PROP_KILL_DEAD_CODE
);
2412 sbitmap_free (blocks
);
2416 /* Same as split_block but update cfg_layout structures. */
2418 cfg_layout_split_block (basic_block bb
, void *insnp
)
2422 edge fallthru
= rtl_split_block (bb
, insn
);
2424 fallthru
->dest
->rbi
->footer
= fallthru
->src
->rbi
->footer
;
2425 fallthru
->src
->rbi
->footer
= NULL
;
2430 /* Redirect Edge to DEST. */
2432 cfg_layout_redirect_edge_and_branch (edge e
, basic_block dest
)
2434 basic_block src
= e
->src
;
2437 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
2440 if (e
->src
!= ENTRY_BLOCK_PTR
2441 && try_redirect_by_replacing_jump (e
, dest
, true))
2444 if (e
->dest
== dest
)
2447 if (e
->src
== ENTRY_BLOCK_PTR
2448 && (e
->flags
& EDGE_FALLTHRU
) && !(e
->flags
& EDGE_COMPLEX
))
2451 fprintf (rtl_dump_file
, "Redirecting entry edge from bb %i to %i\n",
2452 e
->src
->index
, dest
->index
);
2454 redirect_edge_succ (e
, dest
);
2458 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2459 in the case the basic block appears to be in sequence. Avoid this
2462 if (e
->flags
& EDGE_FALLTHRU
)
2464 /* Redirect any branch edges unified with the fallthru one. */
2465 if (GET_CODE (BB_END (src
)) == JUMP_INSN
2466 && label_is_jump_target_p (BB_HEAD (e
->dest
),
2470 fprintf (rtl_dump_file
, "Fallthru edge unified with branch "
2471 "%i->%i redirected to %i\n",
2472 e
->src
->index
, e
->dest
->index
, dest
->index
);
2473 e
->flags
&= ~EDGE_FALLTHRU
;
2474 if (!redirect_branch_edge (e
, dest
))
2476 e
->flags
|= EDGE_FALLTHRU
;
2479 /* In case we are redirecting fallthru edge to the branch edge
2480 of conditional jump, remove it. */
2481 if (src
->succ
->succ_next
2482 && !src
->succ
->succ_next
->succ_next
)
2484 edge s
= e
->succ_next
? e
->succ_next
: src
->succ
;
2486 && any_condjump_p (BB_END (src
))
2487 && onlyjump_p (BB_END (src
)))
2488 delete_insn (BB_END (src
));
2490 redirect_edge_succ_nodup (e
, dest
);
2492 fprintf (rtl_dump_file
, "Fallthru edge %i->%i redirected to %i\n",
2493 e
->src
->index
, e
->dest
->index
, dest
->index
);
2498 ret
= redirect_branch_edge (e
, dest
);
2500 /* We don't want simplejumps in the insn stream during cfglayout. */
2501 if (simplejump_p (BB_END (src
)))
2507 /* Simple wrapper as we always can redirect fallthru edges. */
2509 cfg_layout_redirect_edge_and_branch_force (edge e
, basic_block dest
)
2511 if (!cfg_layout_redirect_edge_and_branch (e
, dest
))
2516 /* Same as flow_delete_block but update cfg_layout structures. */
2518 cfg_layout_delete_block (basic_block bb
)
2520 rtx insn
, next
, prev
= PREV_INSN (BB_HEAD (bb
)), *to
, remaints
;
2522 if (bb
->rbi
->header
)
2524 next
= BB_HEAD (bb
);
2526 NEXT_INSN (prev
) = bb
->rbi
->header
;
2528 set_first_insn (bb
->rbi
->header
);
2529 PREV_INSN (bb
->rbi
->header
) = prev
;
2530 insn
= bb
->rbi
->header
;
2531 while (NEXT_INSN (insn
))
2532 insn
= NEXT_INSN (insn
);
2533 NEXT_INSN (insn
) = next
;
2534 PREV_INSN (next
) = insn
;
2536 next
= NEXT_INSN (BB_END (bb
));
2537 if (bb
->rbi
->footer
)
2539 insn
= bb
->rbi
->footer
;
2542 if (GET_CODE (insn
) == BARRIER
)
2544 if (PREV_INSN (insn
))
2545 NEXT_INSN (PREV_INSN (insn
)) = NEXT_INSN (insn
);
2547 bb
->rbi
->footer
= NEXT_INSN (insn
);
2548 if (NEXT_INSN (insn
))
2549 PREV_INSN (NEXT_INSN (insn
)) = PREV_INSN (insn
);
2551 if (GET_CODE (insn
) == CODE_LABEL
)
2553 insn
= NEXT_INSN (insn
);
2555 if (bb
->rbi
->footer
)
2558 NEXT_INSN (insn
) = bb
->rbi
->footer
;
2559 PREV_INSN (bb
->rbi
->footer
) = insn
;
2560 while (NEXT_INSN (insn
))
2561 insn
= NEXT_INSN (insn
);
2562 NEXT_INSN (insn
) = next
;
2564 PREV_INSN (next
) = insn
;
2566 set_last_insn (insn
);
2569 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
2570 to
= &bb
->next_bb
->rbi
->header
;
2572 to
= &cfg_layout_function_footer
;
2573 rtl_delete_block (bb
);
2576 prev
= NEXT_INSN (prev
);
2578 prev
= get_insns ();
2580 next
= PREV_INSN (next
);
2582 next
= get_last_insn ();
2584 if (next
&& NEXT_INSN (next
) != prev
)
2586 remaints
= unlink_insn_chain (prev
, next
);
2588 while (NEXT_INSN (insn
))
2589 insn
= NEXT_INSN (insn
);
2590 NEXT_INSN (insn
) = *to
;
2592 PREV_INSN (*to
) = insn
;
2597 /* Return true when blocks A and B can be safely merged. */
2599 cfg_layout_can_merge_blocks_p (basic_block a
, basic_block b
)
2601 /* There must be exactly one edge in between the blocks. */
2602 return (a
->succ
&& !a
->succ
->succ_next
&& a
->succ
->dest
== b
2603 && !b
->pred
->pred_next
&& a
!= b
2604 /* Must be simple edge. */
2605 && !(a
->succ
->flags
& EDGE_COMPLEX
)
2606 && a
!= ENTRY_BLOCK_PTR
&& b
!= EXIT_BLOCK_PTR
2607 /* If the jump insn has side effects,
2608 we can't kill the edge. */
2609 && (GET_CODE (BB_END (a
)) != JUMP_INSN
2610 || (reload_completed
2611 ? simplejump_p (BB_END (a
)) : onlyjump_p (BB_END (a
)))));
2614 /* Merge block A and B, abort when it is not possible. */
2616 cfg_layout_merge_blocks (basic_block a
, basic_block b
)
2618 #ifdef ENABLE_CHECKING
2619 if (!cfg_layout_can_merge_blocks_p (a
, b
))
2623 /* If there was a CODE_LABEL beginning B, delete it. */
2624 if (GET_CODE (BB_HEAD (b
)) == CODE_LABEL
)
2625 delete_insn (BB_HEAD (b
));
2627 /* We should have fallthru edge in a, or we can do dummy redirection to get
2629 if (GET_CODE (BB_END (a
)) == JUMP_INSN
)
2630 redirect_edge_and_branch (a
->succ
, b
);
2631 if (GET_CODE (BB_END (a
)) == JUMP_INSN
)
2634 /* Possible line number notes should appear in between. */
2637 rtx first
= BB_END (a
), last
;
2639 last
= emit_insn_after (b
->rbi
->header
, BB_END (a
));
2640 delete_insn_chain (NEXT_INSN (first
), last
);
2641 b
->rbi
->header
= NULL
;
2644 /* In the case basic blocks are not adjacent, move them around. */
2645 if (NEXT_INSN (BB_END (a
)) != BB_HEAD (b
))
2647 rtx first
= unlink_insn_chain (BB_HEAD (b
), BB_END (b
));
2649 emit_insn_after (first
, BB_END (a
));
2650 /* Skip possible DELETED_LABEL insn. */
2651 if (!NOTE_INSN_BASIC_BLOCK_P (first
))
2652 first
= NEXT_INSN (first
);
2653 if (!NOTE_INSN_BASIC_BLOCK_P (first
))
2656 delete_insn (first
);
2658 /* Otherwise just re-associate the instructions. */
2663 for (insn
= BB_HEAD (b
);
2664 insn
!= NEXT_INSN (BB_END (b
));
2665 insn
= NEXT_INSN (insn
))
2666 set_block_for_insn (insn
, a
);
2668 /* Skip possible DELETED_LABEL insn. */
2669 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
2670 insn
= NEXT_INSN (insn
);
2671 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
2674 BB_END (a
) = BB_END (b
);
2678 /* Possible tablejumps and barriers should appear after the block. */
2681 if (!a
->rbi
->footer
)
2682 a
->rbi
->footer
= b
->rbi
->footer
;
2685 rtx last
= a
->rbi
->footer
;
2687 while (NEXT_INSN (last
))
2688 last
= NEXT_INSN (last
);
2689 NEXT_INSN (last
) = b
->rbi
->footer
;
2690 PREV_INSN (b
->rbi
->footer
) = last
;
2692 b
->rbi
->footer
= NULL
;
2696 fprintf (rtl_dump_file
, "Merged blocks %d and %d.\n",
2697 a
->index
, b
->index
);
2699 update_cfg_after_block_merging (a
, b
);
2704 cfg_layout_split_edge (edge e
)
2707 basic_block new_bb
=
2708 create_basic_block (e
->src
!= ENTRY_BLOCK_PTR
2709 ? NEXT_INSN (BB_END (e
->src
)) : get_insns (),
2712 new_bb
->count
= e
->count
;
2713 new_bb
->frequency
= EDGE_FREQUENCY (e
);
2715 new_e
= make_edge (new_bb
, e
->dest
, EDGE_FALLTHRU
);
2716 new_e
->probability
= REG_BR_PROB_BASE
;
2717 new_e
->count
= e
->count
;
2718 redirect_edge_and_branch_force (e
, new_bb
);
2723 /* Implementation of CFG manipulation for linearized RTL. */
2724 struct cfg_hooks rtl_cfg_hooks
= {
2725 rtl_verify_flow_info
,
2727 rtl_create_basic_block
,
2728 rtl_redirect_edge_and_branch
,
2729 rtl_redirect_edge_and_branch_force
,
2732 rtl_can_merge_blocks
, /* can_merge_blocks_p */
2737 /* Implementation of CFG manipulation for cfg layout RTL, where
2738 basic block connected via fallthru edges does not have to be adjacent.
2739 This representation will hopefully become the default one in future
2740 version of the compiler. */
2741 struct cfg_hooks cfg_layout_rtl_cfg_hooks
= {
2742 rtl_verify_flow_info_1
,
2744 cfg_layout_create_basic_block
,
2745 cfg_layout_redirect_edge_and_branch
,
2746 cfg_layout_redirect_edge_and_branch_force
,
2747 cfg_layout_delete_block
,
2748 cfg_layout_split_block
,
2749 cfg_layout_can_merge_blocks_p
,
2750 cfg_layout_merge_blocks
,
2751 cfg_layout_split_edge