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;
1207 FOR_EACH_EDGE (e2, ei, b->succs)
1211 /* ??? In a late-running flow pass, other folks may have deleted basic
1212 blocks by nopping out blocks, leaving multiple BARRIERs between here
1213 and the target label. They ought to be chastized and fixed.
1215 We can also wind up with a sequence of undeletable labels between
1216 one block and the next.
1218 So search through a sequence of barriers, labels, and notes for
1219 the head of block C and assert that we really do fall through. */
1221 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1225 /* Remove what will soon cease being the jump insn from the source block.
1226 If block B consisted only of this single jump, turn it into a deleted
1231 && (any_uncondjump_p (q)
1232 || (EDGE_SUCC (b, 0) == e && ei.index == EDGE_COUNT (b->succs) - 1)))
1235 /* If this was a conditional jump, we need to also delete
1236 the insn that set cc0. */
1237 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1243 /* We don't want a block to end on a line-number note since that has
1244 the potential of changing the code between -g and not -g. */
1245 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1249 /* Selectively unlink the sequence. */
1250 if (q != PREV_INSN (BB_HEAD (c)))
1251 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1253 e->flags |= EDGE_FALLTHRU;
1256 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1257 is back edge of syntactic loop. */
1260 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1269 /* ??? Could we guarantee that bb indices are monotone, so that we could
1270 just compare them? */
1271 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1277 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1278 insn = NEXT_INSN (insn))
1281 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1283 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1290 /* Should move basic block BB after basic block AFTER. NIY. */
1293 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1294 basic_block after ATTRIBUTE_UNUSED)
1299 /* Split a (typically critical) edge. Return the new block.
1300 Abort on abnormal edges.
1302 ??? The code generally expects to be called on critical edges.
1303 The case of a block ending in an unconditional jump to a
1304 block with multiple predecessors is not handled optimally. */
1307 rtl_split_edge (edge edge_in)
1312 /* Abnormal edges cannot be split. */
1313 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1315 /* We are going to place the new block in front of edge destination.
1316 Avoid existence of fallthru predecessors. */
1317 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1322 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1323 if (e->flags & EDGE_FALLTHRU)
1327 force_nonfallthru (e);
1330 /* Create the basic block note.
1332 Where we place the note can have a noticeable impact on the generated
1333 code. Consider this cfg:
1343 If we need to insert an insn on the edge from block 0 to block 1,
1344 we want to ensure the instructions we insert are outside of any
1345 loop notes that physically sit between block 0 and block 1. Otherwise
1346 we confuse the loop optimizer into thinking the loop is a phony. */
1348 if (edge_in->dest != EXIT_BLOCK_PTR
1349 && PREV_INSN (BB_HEAD (edge_in->dest))
1350 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1351 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1352 == NOTE_INSN_LOOP_BEG)
1353 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1354 before = PREV_INSN (BB_HEAD (edge_in->dest));
1355 else if (edge_in->dest != EXIT_BLOCK_PTR)
1356 before = BB_HEAD (edge_in->dest);
1360 /* If this is a fall through edge to the exit block, the blocks might be
1361 not adjacent, and the right place is the after the source. */
1362 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1364 before = NEXT_INSN (BB_END (edge_in->src));
1367 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1368 before = NEXT_INSN (before);
1369 bb = create_basic_block (before, NULL, edge_in->src);
1370 BB_COPY_PARTITION (bb, edge_in->src);
1374 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1375 /* ??? Why not edge_in->dest->prev_bb here? */
1376 BB_COPY_PARTITION (bb, edge_in->dest);
1379 /* ??? This info is likely going to be out of date very soon. */
1380 if (edge_in->dest->global_live_at_start)
1382 bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
1383 bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
1384 COPY_REG_SET (bb->global_live_at_start,
1385 edge_in->dest->global_live_at_start);
1386 COPY_REG_SET (bb->global_live_at_end,
1387 edge_in->dest->global_live_at_start);
1390 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1392 /* For non-fallthru edges, we must adjust the predecessor's
1393 jump instruction to target our new block. */
1394 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1396 edge redirected = redirect_edge_and_branch (edge_in, bb);
1397 gcc_assert (redirected);
1400 redirect_edge_succ (edge_in, bb);
1405 /* Queue instructions for insertion on an edge between two basic blocks.
1406 The new instructions and basic blocks (if any) will not appear in the
1407 CFG until commit_edge_insertions is called. */
1410 insert_insn_on_edge (rtx pattern, edge e)
1412 /* We cannot insert instructions on an abnormal critical edge.
1413 It will be easier to find the culprit if we die now. */
1414 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1416 if (e->insns.r == NULL_RTX)
1419 push_to_sequence (e->insns.r);
1421 emit_insn (pattern);
1423 e->insns.r = get_insns ();
1427 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1428 registers that are killed by the store. */
1430 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1432 regset killed = data;
1435 if (GET_CODE (reg) == SUBREG)
1436 reg = SUBREG_REG (reg);
1439 regno = REGNO (reg);
1440 if (regno >= FIRST_PSEUDO_REGISTER)
1441 SET_REGNO_REG_SET (killed, regno);
1444 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1445 SET_REGNO_REG_SET (killed, regno + i);
1449 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1450 it checks whether this will not clobber the registers that are live on the
1451 edge (i.e. it requires liveness information to be up-to-date) and if there
1452 are some, then it tries to save and restore them. Returns true if
1455 safe_insert_insn_on_edge (rtx insn, edge e)
1459 rtx save_regs = NULL_RTX;
1462 enum machine_mode mode;
1463 reg_set_iterator rsi;
1465 #ifdef AVOID_CCMODE_COPIES
1471 killed = ALLOC_REG_SET (®_obstack);
1473 for (x = insn; x; x = NEXT_INSN (x))
1475 note_stores (PATTERN (x), mark_killed_regs, killed);
1476 bitmap_and_into (killed, e->dest->global_live_at_start);
1478 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno, rsi)
1480 mode = regno < FIRST_PSEUDO_REGISTER
1481 ? reg_raw_mode[regno]
1482 : GET_MODE (regno_reg_rtx[regno]);
1483 if (mode == VOIDmode)
1486 if (noccmode && mode == CCmode)
1489 save_regs = alloc_EXPR_LIST (0,
1492 gen_raw_REG (mode, regno)),
1501 for (x = save_regs; x; x = XEXP (x, 1))
1503 from = XEXP (XEXP (x, 0), 1);
1504 to = XEXP (XEXP (x, 0), 0);
1505 emit_move_insn (to, from);
1508 for (x = save_regs; x; x = XEXP (x, 1))
1510 from = XEXP (XEXP (x, 0), 0);
1511 to = XEXP (XEXP (x, 0), 1);
1512 emit_move_insn (to, from);
1514 insn = get_insns ();
1516 free_EXPR_LIST_list (&save_regs);
1518 insert_insn_on_edge (insn, e);
1520 FREE_REG_SET (killed);
1524 /* Update the CFG for the instructions queued on edge E. */
1527 commit_one_edge_insertion (edge e, int watch_calls)
1529 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1530 basic_block bb = NULL;
1532 /* Pull the insns off the edge now since the edge might go away. */
1534 e->insns.r = NULL_RTX;
1536 /* Special case -- avoid inserting code between call and storing
1537 its return value. */
1538 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1539 && EDGE_COUNT (e->dest->preds) == 1
1540 && e->src != ENTRY_BLOCK_PTR
1541 && CALL_P (BB_END (e->src)))
1543 rtx next = next_nonnote_insn (BB_END (e->src));
1545 after = BB_HEAD (e->dest);
1546 /* The first insn after the call may be a stack pop, skip it. */
1548 && keep_with_call_p (next))
1551 next = next_nonnote_insn (next);
1555 if (!before && !after)
1557 /* Figure out where to put these things. If the destination has
1558 one predecessor, insert there. Except for the exit block. */
1559 if (EDGE_COUNT (e->dest->preds) == 1 && e->dest != EXIT_BLOCK_PTR)
1563 /* Get the location correct wrt a code label, and "nice" wrt
1564 a basic block note, and before everything else. */
1567 tmp = NEXT_INSN (tmp);
1568 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1569 tmp = NEXT_INSN (tmp);
1572 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1573 tmp = NEXT_INSN (tmp);
1574 if (tmp == BB_HEAD (bb))
1577 after = PREV_INSN (tmp);
1579 after = get_last_insn ();
1582 /* If the source has one successor and the edge is not abnormal,
1583 insert there. Except for the entry block. */
1584 else if ((e->flags & EDGE_ABNORMAL) == 0
1585 && EDGE_COUNT (e->src->succs) == 1
1586 && e->src != ENTRY_BLOCK_PTR)
1590 /* It is possible to have a non-simple jump here. Consider a target
1591 where some forms of unconditional jumps clobber a register. This
1592 happens on the fr30 for example.
1594 We know this block has a single successor, so we can just emit
1595 the queued insns before the jump. */
1596 if (JUMP_P (BB_END (bb)))
1597 for (before = BB_END (bb);
1598 NOTE_P (PREV_INSN (before))
1599 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1600 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1604 /* We'd better be fallthru, or we've lost track of
1606 gcc_assert (e->flags & EDGE_FALLTHRU);
1608 after = BB_END (bb);
1611 /* Otherwise we must split the edge. */
1614 bb = split_edge (e);
1615 after = BB_END (bb);
1617 if (flag_reorder_blocks_and_partition
1618 && targetm.have_named_sections
1619 && e->src != ENTRY_BLOCK_PTR
1620 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1621 && !(e->flags & EDGE_CROSSING))
1623 rtx bb_note, new_note, cur_insn;
1626 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1627 cur_insn = NEXT_INSN (cur_insn))
1628 if (NOTE_P (cur_insn)
1629 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1635 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1637 NOTE_BASIC_BLOCK (new_note) = bb;
1638 if (JUMP_P (BB_END (bb))
1639 && !any_condjump_p (BB_END (bb))
1640 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
1641 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1642 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1643 if (after == bb_note)
1649 /* Now that we've found the spot, do the insertion. */
1653 emit_insn_before_noloc (insns, before);
1654 last = prev_nonnote_insn (before);
1657 last = emit_insn_after_noloc (insns, after);
1659 if (returnjump_p (last))
1661 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1662 This is not currently a problem because this only happens
1663 for the (single) epilogue, which already has a fallthru edge
1666 e = EDGE_SUCC (bb, 0);
1667 gcc_assert (e->dest == EXIT_BLOCK_PTR
1668 && EDGE_COUNT (bb->succs) == 1 && (e->flags & EDGE_FALLTHRU));
1670 e->flags &= ~EDGE_FALLTHRU;
1671 emit_barrier_after (last);
1674 delete_insn (before);
1677 gcc_assert (!JUMP_P (last));
1679 /* Mark the basic block for find_sub_basic_blocks. */
1683 /* Update the CFG for all queued instructions. */
1686 commit_edge_insertions (void)
1690 bool changed = false;
1692 #ifdef ENABLE_CHECKING
1693 verify_flow_info ();
1696 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1701 FOR_EACH_EDGE (e, ei, bb->succs)
1705 commit_one_edge_insertion (e, false);
1712 blocks = sbitmap_alloc (last_basic_block);
1713 sbitmap_zero (blocks);
1717 SET_BIT (blocks, bb->index);
1718 /* Check for forgotten bb->aux values before commit_edge_insertions
1720 gcc_assert (bb->aux == &bb->aux);
1723 find_many_sub_basic_blocks (blocks);
1724 sbitmap_free (blocks);
1727 /* Update the CFG for all queued instructions, taking special care of inserting
1728 code on edges between call and storing its return value. */
1731 commit_edge_insertions_watch_calls (void)
1735 bool changed = false;
1737 #ifdef ENABLE_CHECKING
1738 verify_flow_info ();
1741 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1746 FOR_EACH_EDGE (e, ei, bb->succs)
1750 commit_one_edge_insertion (e, true);
1757 blocks = sbitmap_alloc (last_basic_block);
1758 sbitmap_zero (blocks);
1762 SET_BIT (blocks, bb->index);
1763 /* Check for forgotten bb->aux values before commit_edge_insertions
1765 gcc_assert (bb->aux == &bb->aux);
1768 find_many_sub_basic_blocks (blocks);
1769 sbitmap_free (blocks);
1772 /* Print out RTL-specific basic block information (live information
1773 at start and end). */
1776 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1782 s_indent = alloca ((size_t) indent + 1);
1783 memset (s_indent, ' ', (size_t) indent);
1784 s_indent[indent] = '\0';
1786 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1787 dump_regset (bb->global_live_at_start, outf);
1790 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1791 insn = NEXT_INSN (insn))
1792 print_rtl_single (outf, insn);
1794 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1795 dump_regset (bb->global_live_at_end, outf);
1799 /* Like print_rtl, but also print out live information for the start of each
1803 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1808 fprintf (outf, "(nil)\n");
1811 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1812 int max_uid = get_max_uid ();
1813 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1814 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1815 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1819 FOR_EACH_BB_REVERSE (bb)
1823 start[INSN_UID (BB_HEAD (bb))] = bb;
1824 end[INSN_UID (BB_END (bb))] = bb;
1825 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1827 enum bb_state state = IN_MULTIPLE_BB;
1829 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1831 in_bb_p[INSN_UID (x)] = state;
1833 if (x == BB_END (bb))
1838 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1842 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1844 fprintf (outf, ";; Start of basic block %d, registers live:",
1846 dump_regset (bb->global_live_at_start, outf);
1850 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1851 && !NOTE_P (tmp_rtx)
1852 && !BARRIER_P (tmp_rtx))
1853 fprintf (outf, ";; Insn is not within a basic block\n");
1854 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1855 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1857 did_output = print_rtl_single (outf, tmp_rtx);
1859 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1861 fprintf (outf, ";; End of basic block %d, registers live:\n",
1863 dump_regset (bb->global_live_at_end, outf);
1876 if (current_function_epilogue_delay_list != 0)
1878 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1879 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1880 tmp_rtx = XEXP (tmp_rtx, 1))
1881 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1886 update_br_prob_note (basic_block bb)
1889 if (!JUMP_P (BB_END (bb)))
1891 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1892 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1894 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1897 /* Verify the CFG and RTL consistency common for both underlying RTL and
1900 Currently it does following checks:
1902 - test head/end pointers
1903 - overlapping of basic blocks
1904 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1905 - tails of basic blocks (ensure that boundary is necessary)
1906 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1907 and NOTE_INSN_BASIC_BLOCK
1908 - verify that no fall_thru edge crosses hot/cold partition boundaries
1910 In future it can be extended check a lot of other stuff as well
1911 (reachability of basic blocks, life information, etc. etc.). */
1914 rtl_verify_flow_info_1 (void)
1916 const int max_uid = get_max_uid ();
1917 rtx last_head = get_last_insn ();
1918 basic_block *bb_info;
1921 basic_block bb, last_bb_seen;
1923 bb_info = xcalloc (max_uid, sizeof (basic_block));
1925 /* Check bb chain & numbers. */
1926 last_bb_seen = ENTRY_BLOCK_PTR;
1928 FOR_EACH_BB_REVERSE (bb)
1930 rtx head = BB_HEAD (bb);
1931 rtx end = BB_END (bb);
1933 /* Verify the end of the basic block is in the INSN chain. */
1934 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1940 error ("end insn %d for block %d not found in the insn stream",
1941 INSN_UID (end), bb->index);
1945 /* Work backwards from the end to the head of the basic block
1946 to verify the head is in the RTL chain. */
1947 for (; x != NULL_RTX; x = PREV_INSN (x))
1949 /* While walking over the insn chain, verify insns appear
1950 in only one basic block and initialize the BB_INFO array
1951 used by other passes. */
1952 if (bb_info[INSN_UID (x)] != NULL)
1954 error ("insn %d is in multiple basic blocks (%d and %d)",
1955 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1959 bb_info[INSN_UID (x)] = bb;
1966 error ("head insn %d for block %d not found in the insn stream",
1967 INSN_UID (head), bb->index);
1974 /* Now check the basic blocks (boundaries etc.) */
1975 FOR_EACH_BB_REVERSE (bb)
1977 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1978 edge e, fallthru = NULL;
1982 if (INSN_P (BB_END (bb))
1983 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1984 && EDGE_COUNT (bb->succs) >= 2
1985 && any_condjump_p (BB_END (bb)))
1987 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1988 && profile_status != PROFILE_ABSENT)
1990 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1991 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1995 FOR_EACH_EDGE (e, ei, bb->succs)
1997 if (e->flags & EDGE_FALLTHRU)
1999 n_fallthru++, fallthru = e;
2000 if ((e->flags & EDGE_CROSSING)
2001 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
2002 && e->src != ENTRY_BLOCK_PTR
2003 && e->dest != EXIT_BLOCK_PTR))
2005 error ("Fallthru edge crosses section boundary (bb %i)",
2011 if ((e->flags & ~(EDGE_DFS_BACK
2013 | EDGE_IRREDUCIBLE_LOOP
2015 | EDGE_CROSSING)) == 0)
2018 if (e->flags & EDGE_ABNORMAL_CALL)
2021 if (e->flags & EDGE_EH)
2023 else if (e->flags & EDGE_ABNORMAL)
2027 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2028 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2030 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2034 && (!JUMP_P (BB_END (bb))
2035 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2036 || any_condjump_p (BB_END (bb))))))
2038 error ("Too many outgoing branch edges from bb %i", bb->index);
2041 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2043 error ("Fallthru edge after unconditional jump %i", bb->index);
2046 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2048 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2051 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2052 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2054 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2057 if (n_call && !CALL_P (BB_END (bb)))
2059 error ("Call edges for non-call insn in bb %i", bb->index);
2063 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2064 && (!JUMP_P (BB_END (bb))
2065 || any_condjump_p (BB_END (bb))
2066 || any_uncondjump_p (BB_END (bb))))
2068 error ("Abnormal edges for no purpose in bb %i", bb->index);
2072 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2073 /* We may have a barrier inside a basic block before dead code
2074 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2075 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2078 if (! BLOCK_FOR_INSN (x))
2080 ("insn %d inside basic block %d but block_for_insn is NULL",
2081 INSN_UID (x), bb->index);
2084 ("insn %d inside basic block %d but block_for_insn is %i",
2085 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2090 /* OK pointers are correct. Now check the header of basic
2091 block. It ought to contain optional CODE_LABEL followed
2092 by NOTE_BASIC_BLOCK. */
2096 if (BB_END (bb) == x)
2098 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2106 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2108 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2113 if (BB_END (bb) == x)
2114 /* Do checks for empty blocks here. */
2117 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2119 if (NOTE_INSN_BASIC_BLOCK_P (x))
2121 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2122 INSN_UID (x), bb->index);
2126 if (x == BB_END (bb))
2129 if (control_flow_insn_p (x))
2131 error ("in basic block %d:", bb->index);
2132 fatal_insn ("flow control insn inside a basic block", x);
2142 /* Verify the CFG and RTL consistency common for both underlying RTL and
2145 Currently it does following checks:
2146 - all checks of rtl_verify_flow_info_1
2147 - check that all insns are in the basic blocks
2148 (except the switch handling code, barriers and notes)
2149 - check that all returns are followed by barriers
2150 - check that all fallthru edge points to the adjacent blocks. */
2152 rtl_verify_flow_info (void)
2155 int err = rtl_verify_flow_info_1 ();
2158 const rtx rtx_first = get_insns ();
2159 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2161 FOR_EACH_BB_REVERSE (bb)
2166 FOR_EACH_EDGE (e, ei, bb->succs)
2167 if (e->flags & EDGE_FALLTHRU)
2173 /* Ensure existence of barrier in BB with no fallthru edges. */
2174 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2175 insn = NEXT_INSN (insn))
2178 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2180 error ("missing barrier after block %i", bb->index);
2185 else if (e->src != ENTRY_BLOCK_PTR
2186 && e->dest != EXIT_BLOCK_PTR)
2190 if (e->src->next_bb != e->dest)
2193 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2194 e->src->index, e->dest->index);
2198 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2199 insn = NEXT_INSN (insn))
2200 if (BARRIER_P (insn)
2201 #ifndef CASE_DROPS_THROUGH
2204 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2208 error ("verify_flow_info: Incorrect fallthru %i->%i",
2209 e->src->index, e->dest->index);
2210 fatal_insn ("wrong insn in the fallthru edge", insn);
2217 last_bb_seen = ENTRY_BLOCK_PTR;
2219 for (x = rtx_first; x; x = NEXT_INSN (x))
2221 if (NOTE_INSN_BASIC_BLOCK_P (x))
2223 bb = NOTE_BASIC_BLOCK (x);
2226 if (bb != last_bb_seen->next_bb)
2227 internal_error ("basic blocks not laid down consecutively");
2229 curr_bb = last_bb_seen = bb;
2234 switch (GET_CODE (x))
2241 /* An addr_vec is placed outside any basic block. */
2243 && JUMP_P (NEXT_INSN (x))
2244 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2245 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2248 /* But in any case, non-deletable labels can appear anywhere. */
2252 fatal_insn ("insn outside basic block", x);
2257 && returnjump_p (x) && ! condjump_p (x)
2258 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2259 fatal_insn ("return not followed by barrier", x);
2260 if (curr_bb && x == BB_END (curr_bb))
2264 if (num_bb_notes != n_basic_blocks)
2266 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2267 num_bb_notes, n_basic_blocks);
2272 /* Assume that the preceding pass has possibly eliminated jump instructions
2273 or converted the unconditional jumps. Eliminate the edges from CFG.
2274 Return true if any edges are eliminated. */
2277 purge_dead_edges (basic_block bb)
2280 rtx insn = BB_END (bb), note;
2281 bool purged = false;
2285 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2286 if (NONJUMP_INSN_P (insn)
2287 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2291 if (! may_trap_p (PATTERN (insn))
2292 || ((eqnote = find_reg_equal_equiv_note (insn))
2293 && ! may_trap_p (XEXP (eqnote, 0))))
2294 remove_note (insn, note);
2297 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2298 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2300 if (e->flags & EDGE_EH)
2302 if (can_throw_internal (BB_END (bb)))
2308 else if (e->flags & EDGE_ABNORMAL_CALL)
2310 if (CALL_P (BB_END (bb))
2311 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2312 || INTVAL (XEXP (note, 0)) >= 0))
2325 bb->flags |= BB_DIRTY;
2335 /* We do care only about conditional jumps and simplejumps. */
2336 if (!any_condjump_p (insn)
2337 && !returnjump_p (insn)
2338 && !simplejump_p (insn))
2341 /* Branch probability/prediction notes are defined only for
2342 condjumps. We've possibly turned condjump into simplejump. */
2343 if (simplejump_p (insn))
2345 note = find_reg_note (insn, REG_BR_PROB, NULL);
2347 remove_note (insn, note);
2348 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2349 remove_note (insn, note);
2352 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2354 /* Avoid abnormal flags to leak from computed jumps turned
2355 into simplejumps. */
2357 e->flags &= ~EDGE_ABNORMAL;
2359 /* See if this edge is one we should keep. */
2360 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2361 /* A conditional jump can fall through into the next
2362 block, so we should keep the edge. */
2367 else if (e->dest != EXIT_BLOCK_PTR
2368 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2369 /* If the destination block is the target of the jump,
2375 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2376 /* If the destination block is the exit block, and this
2377 instruction is a return, then keep the edge. */
2382 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2383 /* Keep the edges that correspond to exceptions thrown by
2384 this instruction and rematerialize the EDGE_ABNORMAL
2385 flag we just cleared above. */
2387 e->flags |= EDGE_ABNORMAL;
2392 /* We do not need this edge. */
2393 bb->flags |= BB_DIRTY;
2398 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2402 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2407 /* Redistribute probabilities. */
2408 if (EDGE_COUNT (bb->succs) == 1)
2410 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2411 EDGE_SUCC (bb, 0)->count = bb->count;
2415 note = find_reg_note (insn, REG_BR_PROB, NULL);
2419 b = BRANCH_EDGE (bb);
2420 f = FALLTHRU_EDGE (bb);
2421 b->probability = INTVAL (XEXP (note, 0));
2422 f->probability = REG_BR_PROB_BASE - b->probability;
2423 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2424 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2429 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2431 /* First, there should not be any EH or ABCALL edges resulting
2432 from non-local gotos and the like. If there were, we shouldn't
2433 have created the sibcall in the first place. Second, there
2434 should of course never have been a fallthru edge. */
2435 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2436 gcc_assert (EDGE_SUCC (bb, 0)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2441 /* If we don't see a jump insn, we don't know exactly why the block would
2442 have been broken at this point. Look for a simple, non-fallthru edge,
2443 as these are only created by conditional branches. If we find such an
2444 edge we know that there used to be a jump here and can then safely
2445 remove all non-fallthru edges. */
2447 FOR_EACH_EDGE (e, ei, bb->succs)
2448 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2457 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2459 if (!(e->flags & EDGE_FALLTHRU))
2461 bb->flags |= BB_DIRTY;
2469 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2471 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2472 EDGE_SUCC (bb, 0)->count = bb->count;
2475 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2480 /* Search all basic blocks for potentially dead edges and purge them. Return
2481 true if some edge has been eliminated. */
2484 purge_all_dead_edges (int update_life_p)
2492 blocks = sbitmap_alloc (last_basic_block);
2493 sbitmap_zero (blocks);
2498 bool purged_here = purge_dead_edges (bb);
2500 purged |= purged_here;
2501 if (purged_here && update_life_p)
2502 SET_BIT (blocks, bb->index);
2505 if (update_life_p && purged)
2506 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2507 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2508 | PROP_KILL_DEAD_CODE);
2511 sbitmap_free (blocks);
2515 /* Same as split_block but update cfg_layout structures. */
2518 cfg_layout_split_block (basic_block bb, void *insnp)
2521 basic_block new_bb = rtl_split_block (bb, insn);
2523 new_bb->rbi->footer = bb->rbi->footer;
2524 bb->rbi->footer = NULL;
2530 /* Redirect Edge to DEST. */
2532 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2534 basic_block src = e->src;
2537 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2540 if (e->dest == dest)
2543 if (e->src != ENTRY_BLOCK_PTR
2544 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2546 src->flags |= BB_DIRTY;
2550 if (e->src == ENTRY_BLOCK_PTR
2551 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2554 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2555 e->src->index, dest->index);
2557 e->src->flags |= BB_DIRTY;
2558 redirect_edge_succ (e, dest);
2562 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2563 in the case the basic block appears to be in sequence. Avoid this
2566 if (e->flags & EDGE_FALLTHRU)
2568 /* Redirect any branch edges unified with the fallthru one. */
2569 if (JUMP_P (BB_END (src))
2570 && label_is_jump_target_p (BB_HEAD (e->dest),
2576 fprintf (dump_file, "Fallthru edge unified with branch "
2577 "%i->%i redirected to %i\n",
2578 e->src->index, e->dest->index, dest->index);
2579 e->flags &= ~EDGE_FALLTHRU;
2580 redirected = redirect_branch_edge (e, dest);
2581 gcc_assert (redirected);
2582 e->flags |= EDGE_FALLTHRU;
2583 e->src->flags |= BB_DIRTY;
2586 /* In case we are redirecting fallthru edge to the branch edge
2587 of conditional jump, remove it. */
2588 if (EDGE_COUNT (src->succs) == 2)
2595 FOR_EACH_EDGE (tmp, ei, src->succs)
2605 if (EDGE_COUNT (src->succs) > (ix + 1))
2606 s = EDGE_SUCC (src, ix + 1);
2608 s = EDGE_SUCC (src, 0);
2611 && any_condjump_p (BB_END (src))
2612 && onlyjump_p (BB_END (src)))
2613 delete_insn (BB_END (src));
2615 ret = redirect_edge_succ_nodup (e, dest);
2617 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2618 e->src->index, e->dest->index, dest->index);
2621 ret = redirect_branch_edge (e, dest);
2623 /* We don't want simplejumps in the insn stream during cfglayout. */
2624 gcc_assert (!simplejump_p (BB_END (src)));
2626 src->flags |= BB_DIRTY;
2630 /* Simple wrapper as we always can redirect fallthru edges. */
2632 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2634 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2636 gcc_assert (redirected);
2640 /* Same as delete_basic_block but update cfg_layout structures. */
2643 cfg_layout_delete_block (basic_block bb)
2645 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2647 if (bb->rbi->header)
2649 next = BB_HEAD (bb);
2651 NEXT_INSN (prev) = bb->rbi->header;
2653 set_first_insn (bb->rbi->header);
2654 PREV_INSN (bb->rbi->header) = prev;
2655 insn = bb->rbi->header;
2656 while (NEXT_INSN (insn))
2657 insn = NEXT_INSN (insn);
2658 NEXT_INSN (insn) = next;
2659 PREV_INSN (next) = insn;
2661 next = NEXT_INSN (BB_END (bb));
2662 if (bb->rbi->footer)
2664 insn = bb->rbi->footer;
2667 if (BARRIER_P (insn))
2669 if (PREV_INSN (insn))
2670 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2672 bb->rbi->footer = NEXT_INSN (insn);
2673 if (NEXT_INSN (insn))
2674 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2678 insn = NEXT_INSN (insn);
2680 if (bb->rbi->footer)
2683 NEXT_INSN (insn) = bb->rbi->footer;
2684 PREV_INSN (bb->rbi->footer) = insn;
2685 while (NEXT_INSN (insn))
2686 insn = NEXT_INSN (insn);
2687 NEXT_INSN (insn) = next;
2689 PREV_INSN (next) = insn;
2691 set_last_insn (insn);
2694 if (bb->next_bb != EXIT_BLOCK_PTR)
2695 to = &bb->next_bb->rbi->header;
2697 to = &cfg_layout_function_footer;
2698 rtl_delete_block (bb);
2701 prev = NEXT_INSN (prev);
2703 prev = get_insns ();
2705 next = PREV_INSN (next);
2707 next = get_last_insn ();
2709 if (next && NEXT_INSN (next) != prev)
2711 remaints = unlink_insn_chain (prev, next);
2713 while (NEXT_INSN (insn))
2714 insn = NEXT_INSN (insn);
2715 NEXT_INSN (insn) = *to;
2717 PREV_INSN (*to) = insn;
2722 /* Return true when blocks A and B can be safely merged. */
2724 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2726 /* If we are partitioning hot/cold basic blocks, we don't want to
2727 mess up unconditional or indirect jumps that cross between hot
2730 Basic block partitioning may result in some jumps that appear to
2731 be optimizable (or blocks that appear to be mergeable), but which really
2732 must be left untouched (they are required to make it safely across
2733 partition boundaries). See the comments at the top of
2734 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2736 if (flag_reorder_blocks_and_partition
2737 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2738 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2739 || BB_PARTITION (a) != BB_PARTITION (b)))
2742 /* There must be exactly one edge in between the blocks. */
2743 return (EDGE_COUNT (a->succs) == 1
2744 && EDGE_SUCC (a, 0)->dest == b
2745 && EDGE_COUNT (b->preds) == 1
2747 /* Must be simple edge. */
2748 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
2749 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2750 /* If the jump insn has side effects,
2751 we can't kill the edge. */
2752 && (!JUMP_P (BB_END (a))
2753 || (reload_completed
2754 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2757 /* Merge block A and B, abort when it is not possible. */
2759 cfg_layout_merge_blocks (basic_block a, basic_block b)
2761 #ifdef ENABLE_CHECKING
2762 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2765 /* If there was a CODE_LABEL beginning B, delete it. */
2766 if (LABEL_P (BB_HEAD (b)))
2767 delete_insn (BB_HEAD (b));
2769 /* We should have fallthru edge in a, or we can do dummy redirection to get
2771 if (JUMP_P (BB_END (a)))
2772 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2773 gcc_assert (!JUMP_P (BB_END (a)));
2775 /* Possible line number notes should appear in between. */
2778 rtx first = BB_END (a), last;
2780 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2781 delete_insn_chain (NEXT_INSN (first), last);
2782 b->rbi->header = NULL;
2785 /* In the case basic blocks are not adjacent, move them around. */
2786 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2788 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2790 emit_insn_after_noloc (first, BB_END (a));
2791 /* Skip possible DELETED_LABEL insn. */
2792 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2793 first = NEXT_INSN (first);
2794 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2796 delete_insn (first);
2798 /* Otherwise just re-associate the instructions. */
2803 for (insn = BB_HEAD (b);
2804 insn != NEXT_INSN (BB_END (b));
2805 insn = NEXT_INSN (insn))
2806 set_block_for_insn (insn, a);
2808 /* Skip possible DELETED_LABEL insn. */
2809 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2810 insn = NEXT_INSN (insn);
2811 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2813 BB_END (a) = BB_END (b);
2817 /* Possible tablejumps and barriers should appear after the block. */
2820 if (!a->rbi->footer)
2821 a->rbi->footer = b->rbi->footer;
2824 rtx last = a->rbi->footer;
2826 while (NEXT_INSN (last))
2827 last = NEXT_INSN (last);
2828 NEXT_INSN (last) = b->rbi->footer;
2829 PREV_INSN (b->rbi->footer) = last;
2831 b->rbi->footer = NULL;
2835 fprintf (dump_file, "Merged blocks %d and %d.\n",
2836 a->index, b->index);
2842 cfg_layout_split_edge (edge e)
2845 basic_block new_bb =
2846 create_basic_block (e->src != ENTRY_BLOCK_PTR
2847 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2850 /* ??? This info is likely going to be out of date very soon, but we must
2851 create it to avoid getting an ICE later. */
2852 if (e->dest->global_live_at_start)
2854 new_bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
2855 new_bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
2856 COPY_REG_SET (new_bb->global_live_at_start,
2857 e->dest->global_live_at_start);
2858 COPY_REG_SET (new_bb->global_live_at_end,
2859 e->dest->global_live_at_start);
2862 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2863 redirect_edge_and_branch_force (e, new_bb);
2868 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2871 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2875 /* Return 1 if BB ends with a call, possibly followed by some
2876 instructions that must stay with the call, 0 otherwise. */
2879 rtl_block_ends_with_call_p (basic_block bb)
2881 rtx insn = BB_END (bb);
2883 while (!CALL_P (insn)
2884 && insn != BB_HEAD (bb)
2885 && keep_with_call_p (insn))
2886 insn = PREV_INSN (insn);
2887 return (CALL_P (insn));
2890 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2893 rtl_block_ends_with_condjump_p (basic_block bb)
2895 return any_condjump_p (BB_END (bb));
2898 /* Return true if we need to add fake edge to exit.
2899 Helper function for rtl_flow_call_edges_add. */
2902 need_fake_edge_p (rtx insn)
2908 && !SIBLING_CALL_P (insn)
2909 && !find_reg_note (insn, REG_NORETURN, NULL)
2910 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2911 && !CONST_OR_PURE_CALL_P (insn)))
2914 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2915 && MEM_VOLATILE_P (PATTERN (insn)))
2916 || (GET_CODE (PATTERN (insn)) == PARALLEL
2917 && asm_noperands (insn) != -1
2918 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2919 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2922 /* Add fake edges to the function exit for any non constant and non noreturn
2923 calls, volatile inline assembly in the bitmap of blocks specified by
2924 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2927 The goal is to expose cases in which entering a basic block does not imply
2928 that all subsequent instructions must be executed. */
2931 rtl_flow_call_edges_add (sbitmap blocks)
2934 int blocks_split = 0;
2935 int last_bb = last_basic_block;
2936 bool check_last_block = false;
2938 if (n_basic_blocks == 0)
2942 check_last_block = true;
2944 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2946 /* In the last basic block, before epilogue generation, there will be
2947 a fallthru edge to EXIT. Special care is required if the last insn
2948 of the last basic block is a call because make_edge folds duplicate
2949 edges, which would result in the fallthru edge also being marked
2950 fake, which would result in the fallthru edge being removed by
2951 remove_fake_edges, which would result in an invalid CFG.
2953 Moreover, we can't elide the outgoing fake edge, since the block
2954 profiler needs to take this into account in order to solve the minimal
2955 spanning tree in the case that the call doesn't return.
2957 Handle this by adding a dummy instruction in a new last basic block. */
2958 if (check_last_block)
2960 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2961 rtx insn = BB_END (bb);
2963 /* Back up past insns that must be kept in the same block as a call. */
2964 while (insn != BB_HEAD (bb)
2965 && keep_with_call_p (insn))
2966 insn = PREV_INSN (insn);
2968 if (need_fake_edge_p (insn))
2972 e = find_edge (bb, EXIT_BLOCK_PTR);
2975 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2976 commit_edge_insertions ();
2981 /* Now add fake edges to the function exit for any non constant
2982 calls since there is no way that we can determine if they will
2985 for (i = 0; i < last_bb; i++)
2987 basic_block bb = BASIC_BLOCK (i);
2994 if (blocks && !TEST_BIT (blocks, i))
2997 for (insn = BB_END (bb); ; insn = prev_insn)
2999 prev_insn = PREV_INSN (insn);
3000 if (need_fake_edge_p (insn))
3003 rtx split_at_insn = insn;
3005 /* Don't split the block between a call and an insn that should
3006 remain in the same block as the call. */
3008 while (split_at_insn != BB_END (bb)
3009 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3010 split_at_insn = NEXT_INSN (split_at_insn);
3012 /* The handling above of the final block before the epilogue
3013 should be enough to verify that there is no edge to the exit
3014 block in CFG already. Calling make_edge in such case would
3015 cause us to mark that edge as fake and remove it later. */
3017 #ifdef ENABLE_CHECKING
3018 if (split_at_insn == BB_END (bb))
3020 e = find_edge (bb, EXIT_BLOCK_PTR);
3021 gcc_assert (e == NULL);
3025 /* Note that the following may create a new basic block
3026 and renumber the existing basic blocks. */
3027 if (split_at_insn != BB_END (bb))
3029 e = split_block (bb, split_at_insn);
3034 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3037 if (insn == BB_HEAD (bb))
3043 verify_flow_info ();
3045 return blocks_split;
3048 /* Implementation of CFG manipulation for linearized RTL. */
3049 struct cfg_hooks rtl_cfg_hooks = {
3051 rtl_verify_flow_info,
3053 rtl_create_basic_block,
3054 rtl_redirect_edge_and_branch,
3055 rtl_redirect_edge_and_branch_force,
3058 rtl_move_block_after,
3059 rtl_can_merge_blocks, /* can_merge_blocks_p */
3063 NULL, /* can_duplicate_block_p */
3064 NULL, /* duplicate_block */
3066 rtl_make_forwarder_block,
3067 rtl_tidy_fallthru_edge,
3068 rtl_block_ends_with_call_p,
3069 rtl_block_ends_with_condjump_p,
3070 rtl_flow_call_edges_add,
3071 NULL, /* execute_on_growing_pred */
3072 NULL /* execute_on_shrinking_pred */
3075 /* Implementation of CFG manipulation for cfg layout RTL, where
3076 basic block connected via fallthru edges does not have to be adjacent.
3077 This representation will hopefully become the default one in future
3078 version of the compiler. */
3080 /* We do not want to declare these functions in a header file, since they
3081 should only be used through the cfghooks interface, and we do not want to
3082 move them here since it would require also moving quite a lot of related
3084 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3085 extern basic_block cfg_layout_duplicate_bb (basic_block);
3087 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3089 rtl_verify_flow_info_1,
3091 cfg_layout_create_basic_block,
3092 cfg_layout_redirect_edge_and_branch,
3093 cfg_layout_redirect_edge_and_branch_force,
3094 cfg_layout_delete_block,
3095 cfg_layout_split_block,
3096 rtl_move_block_after,
3097 cfg_layout_can_merge_blocks_p,
3098 cfg_layout_merge_blocks,
3101 cfg_layout_can_duplicate_bb_p,
3102 cfg_layout_duplicate_bb,
3103 cfg_layout_split_edge,
3104 rtl_make_forwarder_block,
3106 rtl_block_ends_with_call_p,
3107 rtl_block_ends_with_condjump_p,
3108 rtl_flow_call_edges_add,
3109 NULL, /* execute_on_growing_pred */
3110 NULL /* execute_on_shrinking_pred */