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 basic_block force_nonfallthru_and_redirect (edge, basic_block);
73 static basic_block rtl_split_edge (edge);
74 static bool rtl_move_block_after (basic_block, basic_block);
75 static int rtl_verify_flow_info (void);
76 static basic_block cfg_layout_split_block (basic_block, void *);
77 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
78 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
79 static void cfg_layout_delete_block (basic_block);
80 static void rtl_delete_block (basic_block);
81 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
82 static edge rtl_redirect_edge_and_branch (edge, basic_block);
83 static basic_block rtl_split_block (basic_block, void *);
84 static void rtl_dump_bb (basic_block, FILE *, int);
85 static int rtl_verify_flow_info_1 (void);
86 static void mark_killed_regs (rtx, rtx, void *);
87 static void rtl_make_forwarder_block (edge);
89 /* Return true if NOTE is not one of the ones that must be kept paired,
90 so that we may simply delete it. */
93 can_delete_note_p (rtx note)
95 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
96 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK
97 || NOTE_LINE_NUMBER (note) == NOTE_INSN_UNLIKELY_EXECUTED_CODE);
100 /* True if a given label can be deleted. */
103 can_delete_label_p (rtx label)
105 return (!LABEL_PRESERVE_P (label)
106 /* User declared labels must be preserved. */
107 && LABEL_NAME (label) == 0
108 && !in_expr_list_p (forced_labels, label)
109 && !in_expr_list_p (label_value_list, label));
112 /* Delete INSN by patching it out. Return the next insn. */
115 delete_insn (rtx insn)
117 rtx next = NEXT_INSN (insn);
119 bool really_delete = true;
123 /* Some labels can't be directly removed from the INSN chain, as they
124 might be references via variables, constant pool etc.
125 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
126 if (! can_delete_label_p (insn))
128 const char *name = LABEL_NAME (insn);
130 really_delete = false;
131 PUT_CODE (insn, NOTE);
132 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
133 NOTE_DELETED_LABEL_NAME (insn) = name;
136 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
141 /* If this insn has already been deleted, something is very wrong. */
142 gcc_assert (!INSN_DELETED_P (insn));
144 INSN_DELETED_P (insn) = 1;
147 /* If deleting a jump, decrement the use count of the label. Deleting
148 the label itself should happen in the normal course of block merging. */
151 && LABEL_P (JUMP_LABEL (insn)))
152 LABEL_NUSES (JUMP_LABEL (insn))--;
154 /* Also if deleting an insn that references a label. */
157 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
158 && LABEL_P (XEXP (note, 0)))
160 LABEL_NUSES (XEXP (note, 0))--;
161 remove_note (insn, note);
166 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
167 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
169 rtx pat = PATTERN (insn);
170 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
171 int len = XVECLEN (pat, diff_vec_p);
174 for (i = 0; i < len; i++)
176 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
178 /* When deleting code in bulk (e.g. removing many unreachable
179 blocks) we can delete a label that's a target of the vector
180 before deleting the vector itself. */
182 LABEL_NUSES (label)--;
189 /* Like delete_insn but also purge dead edges from BB. */
191 delete_insn_and_edges (rtx insn)
197 && BLOCK_FOR_INSN (insn)
198 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
200 x = delete_insn (insn);
202 purge_dead_edges (BLOCK_FOR_INSN (insn));
206 /* Unlink a chain of insns between START and FINISH, leaving notes
207 that must be paired. */
210 delete_insn_chain (rtx start, rtx finish)
214 /* Unchain the insns one by one. It would be quicker to delete all of these
215 with a single unchaining, rather than one at a time, but we need to keep
219 next = NEXT_INSN (start);
220 if (NOTE_P (start) && !can_delete_note_p (start))
223 next = delete_insn (start);
231 /* Like delete_insn but also purge dead edges from BB. */
233 delete_insn_chain_and_edges (rtx first, rtx last)
238 && BLOCK_FOR_INSN (last)
239 && BB_END (BLOCK_FOR_INSN (last)) == last)
241 delete_insn_chain (first, last);
243 purge_dead_edges (BLOCK_FOR_INSN (last));
246 /* Create a new basic block consisting of the instructions between HEAD and END
247 inclusive. This function is designed to allow fast BB construction - reuses
248 the note and basic block struct in BB_NOTE, if any and do not grow
249 BASIC_BLOCK chain and should be used directly only by CFG construction code.
250 END can be NULL in to create new empty basic block before HEAD. Both END
251 and HEAD can be NULL to create basic block at the end of INSN chain.
252 AFTER is the basic block we should be put after. */
255 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
260 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
263 /* If we found an existing note, thread it back onto the chain. */
271 after = PREV_INSN (head);
275 if (after != bb_note && NEXT_INSN (after) != bb_note)
276 reorder_insns_nobb (bb_note, bb_note, after);
280 /* Otherwise we must create a note and a basic block structure. */
286 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
287 else if (LABEL_P (head) && end)
289 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
295 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
301 NOTE_BASIC_BLOCK (bb_note) = bb;
304 /* Always include the bb note in the block. */
305 if (NEXT_INSN (end) == bb_note)
310 bb->index = last_basic_block++;
312 link_block (bb, after);
313 BASIC_BLOCK (bb->index) = bb;
314 update_bb_for_insn (bb);
315 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
317 /* Tag the block so that we know it has been used when considering
318 other basic block notes. */
324 /* Create new basic block consisting of instructions in between HEAD and END
325 and place it to the BB chain after block AFTER. END can be NULL in to
326 create new empty basic block before HEAD. Both END and HEAD can be NULL to
327 create basic block at the end of INSN chain. */
330 rtl_create_basic_block (void *headp, void *endp, basic_block after)
332 rtx head = headp, end = endp;
335 /* Grow the basic block array if needed. */
336 if ((size_t) last_basic_block >= VARRAY_SIZE (basic_block_info))
338 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
339 VARRAY_GROW (basic_block_info, new_size);
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 initialize_bb_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. */
381 maybe_remove_eh_handler (insn);
383 /* Include any jump table following the basic block. */
385 if (tablejump_p (end, NULL, &tmp))
388 /* Include any barrier that may follow the basic block. */
389 tmp = next_nonnote_insn (end);
390 if (tmp && BARRIER_P (tmp))
393 /* Selectively delete the entire chain. */
395 delete_insn_chain (insn, end);
398 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
401 compute_bb_for_insn (void)
407 rtx end = BB_END (bb);
410 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
412 BLOCK_FOR_INSN (insn) = bb;
419 /* Release the basic_block_for_insn array. */
422 free_bb_for_insn (void)
425 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
426 if (!BARRIER_P (insn))
427 BLOCK_FOR_INSN (insn) = NULL;
430 /* Return RTX to emit after when we want to emit code on the entry of function. */
432 entry_of_function (void)
434 return (n_basic_blocks ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
437 /* Update insns block within BB. */
440 update_bb_for_insn (basic_block bb)
444 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
446 if (!BARRIER_P (insn))
447 set_block_for_insn (insn, bb);
448 if (insn == BB_END (bb))
453 /* Creates a new basic block just after basic block B by splitting
454 everything after specified instruction I. */
457 rtl_split_block (basic_block bb, void *insnp)
465 insn = first_insn_after_basic_block_note (bb);
468 insn = PREV_INSN (insn);
470 insn = get_last_insn ();
473 /* We probably should check type of the insn so that we do not create
474 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
476 if (insn == BB_END (bb))
477 emit_note_after (NOTE_INSN_DELETED, insn);
479 /* Create the new basic block. */
480 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
481 BB_COPY_PARTITION (new_bb, bb);
484 /* Redirect the outgoing edges. */
485 new_bb->succ = bb->succ;
487 for (e = new_bb->succ; e; e = e->succ_next)
490 if (bb->global_live_at_start)
492 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
493 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
494 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
496 /* We now have to calculate which registers are live at the end
497 of the split basic block and at the start of the new basic
498 block. Start with those registers that are known to be live
499 at the end of the original basic block and get
500 propagate_block to determine which registers are live. */
501 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
502 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
503 COPY_REG_SET (bb->global_live_at_end,
504 new_bb->global_live_at_start);
505 #ifdef HAVE_conditional_execution
506 /* In the presence of conditional execution we are not able to update
507 liveness precisely. */
508 if (reload_completed)
510 bb->flags |= BB_DIRTY;
511 new_bb->flags |= BB_DIRTY;
519 /* Blocks A and B are to be merged into a single block A. The insns
520 are already contiguous. */
523 rtl_merge_blocks (basic_block a, basic_block b)
525 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
526 rtx del_first = NULL_RTX, del_last = NULL_RTX;
529 /* If there was a CODE_LABEL beginning B, delete it. */
530 if (LABEL_P (b_head))
532 /* Detect basic blocks with nothing but a label. This can happen
533 in particular at the end of a function. */
537 del_first = del_last = b_head;
538 b_head = NEXT_INSN (b_head);
541 /* Delete the basic block note and handle blocks containing just that
543 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
551 b_head = NEXT_INSN (b_head);
554 /* If there was a jump out of A, delete it. */
559 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
561 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
562 || prev == BB_HEAD (a))
568 /* If this was a conditional jump, we need to also delete
569 the insn that set cc0. */
570 if (only_sets_cc0_p (prev))
574 prev = prev_nonnote_insn (prev);
581 a_end = PREV_INSN (del_first);
583 else if (BARRIER_P (NEXT_INSN (a_end)))
584 del_first = NEXT_INSN (a_end);
586 /* Delete everything marked above as well as crap that might be
587 hanging out between the two blocks. */
589 delete_insn_chain (del_first, del_last);
591 /* Reassociate the insns of B with A. */
596 for (x = a_end; x != b_end; x = NEXT_INSN (x))
597 set_block_for_insn (x, a);
599 set_block_for_insn (b_end, a);
607 /* Return true when block A and B can be merged. */
609 rtl_can_merge_blocks (basic_block a,basic_block b)
611 /* If we are partitioning hot/cold basic blocks, we don't want to
612 mess up unconditional or indirect jumps that cross between hot
615 Basic block partitioning may result in some jumps that appear to
616 be optimizable (or blocks that appear to be mergeable), but which really
617 must be left untouched (they are required to make it safely across
618 partition boundaries). See the comments at the top of
619 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
621 if (flag_reorder_blocks_and_partition
622 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
623 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
624 || BB_PARTITION (a) != BB_PARTITION (b)))
627 /* There must be exactly one edge in between the blocks. */
628 return (a->succ && !a->succ->succ_next && a->succ->dest == b
629 && !b->pred->pred_next && a != b
630 /* Must be simple edge. */
631 && !(a->succ->flags & EDGE_COMPLEX)
633 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
634 /* If the jump insn has side effects,
635 we can't kill the edge. */
636 && (!JUMP_P (BB_END (a))
638 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
641 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
645 block_label (basic_block block)
647 if (block == EXIT_BLOCK_PTR)
650 if (!LABEL_P (BB_HEAD (block)))
652 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
655 return BB_HEAD (block);
658 /* Attempt to perform edge redirection by replacing possibly complex jump
659 instruction by unconditional jump or removing jump completely. This can
660 apply only if all edges now point to the same block. The parameters and
661 return values are equivalent to redirect_edge_and_branch. */
664 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
666 basic_block src = e->src;
667 rtx insn = BB_END (src), kill_from;
673 /* If we are partitioning hot/cold basic blocks, we don't want to
674 mess up unconditional or indirect jumps that cross between hot
677 Basic block partitioning may result in some jumps that appear to
678 be optimizable (or blocks that appear to be mergeable), but which really
679 must be left untouched (they are required to make it safely across
680 partition boundaries). See the comments at the top of
681 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
683 if (flag_reorder_blocks_and_partition
684 && (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
685 || BB_PARTITION (src) != BB_PARTITION (target)))
688 /* Verify that all targets will be TARGET. */
689 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
690 if (tmp->dest != target && tmp != e)
693 if (tmp || !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 (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 (src->succ->succ_next)
818 remove_edge (src->succ);
821 e->flags = EDGE_FALLTHRU;
825 e->probability = REG_BR_PROB_BASE;
826 e->count = src->count;
828 /* We don't want a block to end on a line-number note since that has
829 the potential of changing the code between -g and not -g. */
830 while (NOTE_P (BB_END (e->src))
831 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
832 delete_insn (BB_END (e->src));
834 if (e->dest != target)
835 redirect_edge_succ (e, target);
840 /* Return last loop_beg note appearing after INSN, before start of next
841 basic block. Return INSN if there are no such notes.
843 When emitting jump to redirect a fallthru edge, it should always appear
844 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
845 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
849 last_loop_beg_note (rtx insn)
853 for (insn = NEXT_INSN (insn); insn && NOTE_P (insn)
854 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
855 insn = NEXT_INSN (insn))
856 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
862 /* Redirect edge representing branch of (un)conditional jump or tablejump,
865 redirect_branch_edge (edge e, basic_block target)
868 rtx old_label = BB_HEAD (e->dest);
869 basic_block src = e->src;
870 rtx insn = BB_END (src);
872 /* We can only redirect non-fallthru edges of jump insn. */
873 if (e->flags & EDGE_FALLTHRU)
875 else if (!JUMP_P (insn))
878 /* Recognize a tablejump and adjust all matching cases. */
879 if (tablejump_p (insn, NULL, &tmp))
883 rtx new_label = block_label (target);
885 if (target == EXIT_BLOCK_PTR)
887 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
888 vec = XVEC (PATTERN (tmp), 0);
890 vec = XVEC (PATTERN (tmp), 1);
892 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
893 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
895 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
896 --LABEL_NUSES (old_label);
897 ++LABEL_NUSES (new_label);
900 /* Handle casesi dispatch insns. */
901 if ((tmp = single_set (insn)) != NULL
902 && SET_DEST (tmp) == pc_rtx
903 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
904 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
905 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
907 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
909 --LABEL_NUSES (old_label);
910 ++LABEL_NUSES (new_label);
915 /* ?? We may play the games with moving the named labels from
916 one basic block to the other in case only one computed_jump is
918 if (computed_jump_p (insn)
919 /* A return instruction can't be redirected. */
920 || returnjump_p (insn))
923 /* If the insn doesn't go where we think, we're confused. */
924 gcc_assert (JUMP_LABEL (insn) == old_label);
926 /* If the substitution doesn't succeed, die. This can happen
927 if the back end emitted unrecognizable instructions or if
928 target is exit block on some arches. */
929 if (!redirect_jump (insn, block_label (target), 0))
931 gcc_assert (target == EXIT_BLOCK_PTR);
937 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
938 e->src->index, e->dest->index, target->index);
940 if (e->dest != target)
941 e = redirect_edge_succ_nodup (e, target);
945 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
946 expense of adding new instructions or reordering basic blocks.
948 Function can be also called with edge destination equivalent to the TARGET.
949 Then it should try the simplifications and do nothing if none is possible.
951 Return edge representing the branch if transformation succeeded. Return NULL
953 We still return NULL in case E already destinated TARGET and we didn't
954 managed to simplify instruction stream. */
957 rtl_redirect_edge_and_branch (edge e, basic_block target)
960 basic_block src = e->src;
962 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
965 if (e->dest == target)
968 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
970 src->flags |= BB_DIRTY;
974 ret = redirect_branch_edge (e, target);
978 src->flags |= BB_DIRTY;
982 /* Like force_nonfallthru below, but additionally performs redirection
983 Used by redirect_edge_and_branch_force. */
986 force_nonfallthru_and_redirect (edge e, basic_block target)
988 basic_block jump_block, new_bb = NULL, src = e->src;
991 int abnormal_edge_flags = 0;
993 /* In the case the last instruction is conditional jump to the next
994 instruction, first redirect the jump itself and then continue
995 by creating a basic block afterwards to redirect fallthru edge. */
996 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
997 && any_condjump_p (BB_END (e->src))
998 /* When called from cfglayout, fallthru edges do not
999 necessarily go to the next block. */
1000 && e->src->next_bb == e->dest
1001 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1004 edge b = unchecked_make_edge (e->src, target, 0);
1007 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1008 gcc_assert (redirected);
1010 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1013 int prob = INTVAL (XEXP (note, 0));
1015 b->probability = prob;
1016 b->count = e->count * prob / REG_BR_PROB_BASE;
1017 e->probability -= e->probability;
1018 e->count -= b->count;
1019 if (e->probability < 0)
1026 if (e->flags & EDGE_ABNORMAL)
1028 /* Irritating special case - fallthru edge to the same block as abnormal
1030 We can't redirect abnormal edge, but we still can split the fallthru
1031 one and create separate abnormal edge to original destination.
1032 This allows bb-reorder to make such edge non-fallthru. */
1033 gcc_assert (e->dest == target);
1034 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1035 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1039 gcc_assert (e->flags & EDGE_FALLTHRU);
1040 if (e->src == ENTRY_BLOCK_PTR)
1042 /* We can't redirect the entry block. Create an empty block
1043 at the start of the function which we use to add the new
1047 = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1049 /* Change the existing edge's source to be the new block, and add
1050 a new edge from the entry block to the new block. */
1052 for (pe1 = &ENTRY_BLOCK_PTR->succ; *pe1; pe1 = &(*pe1)->succ_next)
1055 *pe1 = e->succ_next;
1060 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1064 if (e->src->succ->succ_next || abnormal_edge_flags)
1066 /* Create the new structures. */
1068 /* If the old block ended with a tablejump, skip its table
1069 by searching forward from there. Otherwise start searching
1070 forward from the last instruction of the old block. */
1071 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1072 note = BB_END (e->src);
1074 /* Position the new block correctly relative to loop notes. */
1075 note = last_loop_beg_note (note);
1076 note = NEXT_INSN (note);
1078 jump_block = create_basic_block (note, NULL, e->src);
1079 jump_block->count = e->count;
1080 jump_block->frequency = EDGE_FREQUENCY (e);
1081 jump_block->loop_depth = target->loop_depth;
1083 if (target->global_live_at_start)
1085 jump_block->global_live_at_start
1086 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1087 jump_block->global_live_at_end
1088 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1089 COPY_REG_SET (jump_block->global_live_at_start,
1090 target->global_live_at_start);
1091 COPY_REG_SET (jump_block->global_live_at_end,
1092 target->global_live_at_start);
1095 /* Make sure new block ends up in correct hot/cold section. */
1097 BB_COPY_PARTITION (jump_block, e->src);
1098 if (flag_reorder_blocks_and_partition
1099 && targetm.have_named_sections)
1101 if (BB_PARTITION (jump_block) == BB_COLD_PARTITION)
1103 rtx bb_note, new_note;
1104 for (bb_note = BB_HEAD (jump_block);
1105 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1106 bb_note = NEXT_INSN (bb_note))
1107 if (NOTE_P (bb_note)
1108 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1110 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1112 NOTE_BASIC_BLOCK (new_note) = jump_block;
1114 if (JUMP_P (BB_END (jump_block))
1115 && !any_condjump_p (BB_END (jump_block))
1116 && (jump_block->succ->flags & EDGE_CROSSING))
1117 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1118 (REG_CROSSING_JUMP, NULL_RTX,
1119 REG_NOTES (BB_END (jump_block)));
1123 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1124 new_edge->probability = e->probability;
1125 new_edge->count = e->count;
1127 /* Redirect old edge. */
1128 redirect_edge_pred (e, jump_block);
1129 e->probability = REG_BR_PROB_BASE;
1131 new_bb = jump_block;
1134 jump_block = e->src;
1136 e->flags &= ~EDGE_FALLTHRU;
1137 if (target == EXIT_BLOCK_PTR)
1140 emit_jump_insn_after (gen_return (), BB_END (jump_block));
1147 rtx label = block_label (target);
1148 emit_jump_insn_after (gen_jump (label), BB_END (jump_block));
1149 JUMP_LABEL (BB_END (jump_block)) = label;
1150 LABEL_NUSES (label)++;
1153 emit_barrier_after (BB_END (jump_block));
1154 redirect_edge_succ_nodup (e, target);
1156 if (abnormal_edge_flags)
1157 make_edge (src, target, abnormal_edge_flags);
1162 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1163 (and possibly create new basic block) to make edge non-fallthru.
1164 Return newly created BB or NULL if none. */
1167 force_nonfallthru (edge e)
1169 return force_nonfallthru_and_redirect (e, e->dest);
1172 /* Redirect edge even at the expense of creating new jump insn or
1173 basic block. Return new basic block if created, NULL otherwise.
1174 Abort if conversion is impossible. */
1177 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1179 if (redirect_edge_and_branch (e, target)
1180 || e->dest == target)
1183 /* In case the edge redirection failed, try to force it to be non-fallthru
1184 and redirect newly created simplejump. */
1185 return force_nonfallthru_and_redirect (e, target);
1188 /* The given edge should potentially be a fallthru edge. If that is in
1189 fact true, delete the jump and barriers that are in the way. */
1192 rtl_tidy_fallthru_edge (edge e)
1195 basic_block b = e->src, c = b->next_bb;
1197 /* ??? In a late-running flow pass, other folks may have deleted basic
1198 blocks by nopping out blocks, leaving multiple BARRIERs between here
1199 and the target label. They ought to be chastized and fixed.
1201 We can also wind up with a sequence of undeletable labels between
1202 one block and the next.
1204 So search through a sequence of barriers, labels, and notes for
1205 the head of block C and assert that we really do fall through. */
1207 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1211 /* Remove what will soon cease being the jump insn from the source block.
1212 If block B consisted only of this single jump, turn it into a deleted
1217 && (any_uncondjump_p (q)
1218 || (b->succ == e && e->succ_next == NULL)))
1221 /* If this was a conditional jump, we need to also delete
1222 the insn that set cc0. */
1223 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1229 /* We don't want a block to end on a line-number note since that has
1230 the potential of changing the code between -g and not -g. */
1231 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1235 /* Selectively unlink the sequence. */
1236 if (q != PREV_INSN (BB_HEAD (c)))
1237 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1239 e->flags |= EDGE_FALLTHRU;
1242 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1243 is back edge of syntactic loop. */
1246 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1255 /* ??? Could we guarantee that bb indices are monotone, so that we could
1256 just compare them? */
1257 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1263 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1264 insn = NEXT_INSN (insn))
1267 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1269 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1276 /* Should move basic block BB after basic block AFTER. NIY. */
1279 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1280 basic_block after ATTRIBUTE_UNUSED)
1285 /* Split a (typically critical) edge. Return the new block.
1286 Abort on abnormal edges.
1288 ??? The code generally expects to be called on critical edges.
1289 The case of a block ending in an unconditional jump to a
1290 block with multiple predecessors is not handled optimally. */
1293 rtl_split_edge (edge edge_in)
1298 /* Abnormal edges cannot be split. */
1299 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1301 /* We are going to place the new block in front of edge destination.
1302 Avoid existence of fallthru predecessors. */
1303 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1307 for (e = edge_in->dest->pred; e; e = e->pred_next)
1308 if (e->flags & EDGE_FALLTHRU)
1312 force_nonfallthru (e);
1315 /* Create the basic block note.
1317 Where we place the note can have a noticeable impact on the generated
1318 code. Consider this cfg:
1328 If we need to insert an insn on the edge from block 0 to block 1,
1329 we want to ensure the instructions we insert are outside of any
1330 loop notes that physically sit between block 0 and block 1. Otherwise
1331 we confuse the loop optimizer into thinking the loop is a phony. */
1333 if (edge_in->dest != EXIT_BLOCK_PTR
1334 && PREV_INSN (BB_HEAD (edge_in->dest))
1335 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1336 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1337 == NOTE_INSN_LOOP_BEG)
1338 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1339 before = PREV_INSN (BB_HEAD (edge_in->dest));
1340 else if (edge_in->dest != EXIT_BLOCK_PTR)
1341 before = BB_HEAD (edge_in->dest);
1345 /* If this is a fall through edge to the exit block, the blocks might be
1346 not adjacent, and the right place is the after the source. */
1347 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1349 before = NEXT_INSN (BB_END (edge_in->src));
1352 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1353 before = NEXT_INSN (before);
1354 bb = create_basic_block (before, NULL, edge_in->src);
1355 BB_COPY_PARTITION (bb, edge_in->src);
1359 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1360 /* ??? Why not edge_in->dest->prev_bb here? */
1361 BB_COPY_PARTITION (bb, edge_in->dest);
1364 /* ??? This info is likely going to be out of date very soon. */
1365 if (edge_in->dest->global_live_at_start)
1367 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1368 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1369 COPY_REG_SET (bb->global_live_at_start,
1370 edge_in->dest->global_live_at_start);
1371 COPY_REG_SET (bb->global_live_at_end,
1372 edge_in->dest->global_live_at_start);
1375 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1377 /* For non-fallthru edges, we must adjust the predecessor's
1378 jump instruction to target our new block. */
1379 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1381 edge redirected = redirect_edge_and_branch (edge_in, bb);
1382 gcc_assert (redirected);
1385 redirect_edge_succ (edge_in, bb);
1390 /* Queue instructions for insertion on an edge between two basic blocks.
1391 The new instructions and basic blocks (if any) will not appear in the
1392 CFG until commit_edge_insertions is called. */
1395 insert_insn_on_edge (rtx pattern, edge e)
1397 /* We cannot insert instructions on an abnormal critical edge.
1398 It will be easier to find the culprit if we die now. */
1399 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1401 if (e->insns.r == NULL_RTX)
1404 push_to_sequence (e->insns.r);
1406 emit_insn (pattern);
1408 e->insns.r = get_insns ();
1412 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1413 registers that are killed by the store. */
1415 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1417 regset killed = data;
1420 if (GET_CODE (reg) == SUBREG)
1421 reg = SUBREG_REG (reg);
1424 regno = REGNO (reg);
1425 if (regno >= FIRST_PSEUDO_REGISTER)
1426 SET_REGNO_REG_SET (killed, regno);
1429 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1430 SET_REGNO_REG_SET (killed, regno + i);
1434 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1435 it checks whether this will not clobber the registers that are live on the
1436 edge (i.e. it requires liveness information to be up-to-date) and if there
1437 are some, then it tries to save and restore them. Returns true if
1440 safe_insert_insn_on_edge (rtx insn, edge e)
1443 regset_head killed_head;
1444 regset killed = INITIALIZE_REG_SET (killed_head);
1445 rtx save_regs = NULL_RTX;
1446 int regno, noccmode;
1447 enum machine_mode mode;
1449 #ifdef AVOID_CCMODE_COPIES
1455 for (x = insn; x; x = NEXT_INSN (x))
1457 note_stores (PATTERN (x), mark_killed_regs, killed);
1458 bitmap_operation (killed, killed, e->dest->global_live_at_start,
1461 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno,
1463 mode = regno < FIRST_PSEUDO_REGISTER
1464 ? reg_raw_mode[regno]
1465 : GET_MODE (regno_reg_rtx[regno]);
1466 if (mode == VOIDmode)
1469 if (noccmode && mode == CCmode)
1472 save_regs = alloc_EXPR_LIST (0,
1475 gen_raw_REG (mode, regno)),
1484 for (x = save_regs; x; x = XEXP (x, 1))
1486 from = XEXP (XEXP (x, 0), 1);
1487 to = XEXP (XEXP (x, 0), 0);
1488 emit_move_insn (to, from);
1491 for (x = save_regs; x; x = XEXP (x, 1))
1493 from = XEXP (XEXP (x, 0), 0);
1494 to = XEXP (XEXP (x, 0), 1);
1495 emit_move_insn (to, from);
1497 insn = get_insns ();
1499 free_EXPR_LIST_list (&save_regs);
1501 insert_insn_on_edge (insn, e);
1503 FREE_REG_SET (killed);
1507 /* Update the CFG for the instructions queued on edge E. */
1510 commit_one_edge_insertion (edge e, int watch_calls)
1512 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1513 basic_block bb = NULL;
1515 /* Pull the insns off the edge now since the edge might go away. */
1517 e->insns.r = NULL_RTX;
1519 /* Special case -- avoid inserting code between call and storing
1520 its return value. */
1521 if (watch_calls && (e->flags & EDGE_FALLTHRU) && !e->dest->pred->pred_next
1522 && e->src != ENTRY_BLOCK_PTR
1523 && CALL_P (BB_END (e->src)))
1525 rtx next = next_nonnote_insn (BB_END (e->src));
1527 after = BB_HEAD (e->dest);
1528 /* The first insn after the call may be a stack pop, skip it. */
1530 && keep_with_call_p (next))
1533 next = next_nonnote_insn (next);
1537 if (!before && !after)
1539 /* Figure out where to put these things. If the destination has
1540 one predecessor, insert there. Except for the exit block. */
1541 if (e->dest->pred->pred_next == NULL && e->dest != EXIT_BLOCK_PTR)
1545 /* Get the location correct wrt a code label, and "nice" wrt
1546 a basic block note, and before everything else. */
1549 tmp = NEXT_INSN (tmp);
1550 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1551 tmp = NEXT_INSN (tmp);
1554 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1555 tmp = NEXT_INSN (tmp);
1556 if (tmp == BB_HEAD (bb))
1559 after = PREV_INSN (tmp);
1561 after = get_last_insn ();
1564 /* If the source has one successor and the edge is not abnormal,
1565 insert there. Except for the entry block. */
1566 else if ((e->flags & EDGE_ABNORMAL) == 0
1567 && e->src->succ->succ_next == NULL
1568 && e->src != ENTRY_BLOCK_PTR)
1572 /* It is possible to have a non-simple jump here. Consider a target
1573 where some forms of unconditional jumps clobber a register. This
1574 happens on the fr30 for example.
1576 We know this block has a single successor, so we can just emit
1577 the queued insns before the jump. */
1578 if (JUMP_P (BB_END (bb)))
1579 for (before = BB_END (bb);
1580 NOTE_P (PREV_INSN (before))
1581 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1582 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1586 /* We'd better be fallthru, or we've lost track of
1588 gcc_assert (e->flags & EDGE_FALLTHRU);
1590 after = BB_END (bb);
1593 /* Otherwise we must split the edge. */
1596 bb = split_edge (e);
1597 after = BB_END (bb);
1599 if (flag_reorder_blocks_and_partition
1600 && targetm.have_named_sections
1601 && e->src != ENTRY_BLOCK_PTR
1602 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1603 && !(e->flags & EDGE_CROSSING))
1605 rtx bb_note, new_note, cur_insn;
1608 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1609 cur_insn = NEXT_INSN (cur_insn))
1610 if (NOTE_P (cur_insn)
1611 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1617 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1619 NOTE_BASIC_BLOCK (new_note) = bb;
1620 if (JUMP_P (BB_END (bb))
1621 && !any_condjump_p (BB_END (bb))
1622 && (bb->succ->flags & EDGE_CROSSING))
1623 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1624 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1625 if (after == bb_note)
1631 /* Now that we've found the spot, do the insertion. */
1635 emit_insn_before (insns, before);
1636 last = prev_nonnote_insn (before);
1639 last = emit_insn_after (insns, after);
1641 if (returnjump_p (last))
1643 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1644 This is not currently a problem because this only happens
1645 for the (single) epilogue, which already has a fallthru edge
1649 gcc_assert (e->dest == EXIT_BLOCK_PTR
1650 && !e->succ_next && (e->flags & EDGE_FALLTHRU));
1652 e->flags &= ~EDGE_FALLTHRU;
1653 emit_barrier_after (last);
1656 delete_insn (before);
1659 gcc_assert (!JUMP_P (last));
1661 /* Mark the basic block for find_sub_basic_blocks. */
1665 /* Update the CFG for all queued instructions. */
1668 commit_edge_insertions (void)
1672 bool changed = false;
1674 #ifdef ENABLE_CHECKING
1675 verify_flow_info ();
1678 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1682 for (e = bb->succ; e; e = next)
1684 next = e->succ_next;
1688 commit_one_edge_insertion (e, false);
1696 blocks = sbitmap_alloc (last_basic_block);
1697 sbitmap_zero (blocks);
1701 SET_BIT (blocks, bb->index);
1702 /* Check for forgotten bb->aux values before commit_edge_insertions
1704 gcc_assert (bb->aux == &bb->aux);
1707 find_many_sub_basic_blocks (blocks);
1708 sbitmap_free (blocks);
1711 /* Update the CFG for all queued instructions, taking special care of inserting
1712 code on edges between call and storing its return value. */
1715 commit_edge_insertions_watch_calls (void)
1719 bool changed = false;
1721 #ifdef ENABLE_CHECKING
1722 verify_flow_info ();
1725 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1729 for (e = bb->succ; e; e = next)
1731 next = e->succ_next;
1735 commit_one_edge_insertion (e, true);
1743 blocks = sbitmap_alloc (last_basic_block);
1744 sbitmap_zero (blocks);
1748 SET_BIT (blocks, bb->index);
1749 /* Check for forgotten bb->aux values before commit_edge_insertions
1751 gcc_assert (bb->aux == &bb->aux);
1754 find_many_sub_basic_blocks (blocks);
1755 sbitmap_free (blocks);
1758 /* Print out RTL-specific basic block information (live information
1759 at start and end). */
1762 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1768 s_indent = alloca ((size_t) indent + 1);
1769 memset (s_indent, ' ', (size_t) indent);
1770 s_indent[indent] = '\0';
1772 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1773 dump_regset (bb->global_live_at_start, outf);
1776 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1777 insn = NEXT_INSN (insn))
1778 print_rtl_single (outf, insn);
1780 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1781 dump_regset (bb->global_live_at_end, outf);
1785 /* Like print_rtl, but also print out live information for the start of each
1789 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1794 fprintf (outf, "(nil)\n");
1797 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1798 int max_uid = get_max_uid ();
1799 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1800 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1801 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1805 FOR_EACH_BB_REVERSE (bb)
1809 start[INSN_UID (BB_HEAD (bb))] = bb;
1810 end[INSN_UID (BB_END (bb))] = bb;
1811 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1813 enum bb_state state = IN_MULTIPLE_BB;
1815 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1817 in_bb_p[INSN_UID (x)] = state;
1819 if (x == BB_END (bb))
1824 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1828 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1830 fprintf (outf, ";; Start of basic block %d, registers live:",
1832 dump_regset (bb->global_live_at_start, outf);
1836 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1837 && !NOTE_P (tmp_rtx)
1838 && !BARRIER_P (tmp_rtx))
1839 fprintf (outf, ";; Insn is not within a basic block\n");
1840 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1841 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1843 did_output = print_rtl_single (outf, tmp_rtx);
1845 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1847 fprintf (outf, ";; End of basic block %d, registers live:\n",
1849 dump_regset (bb->global_live_at_end, outf);
1862 if (current_function_epilogue_delay_list != 0)
1864 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1865 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1866 tmp_rtx = XEXP (tmp_rtx, 1))
1867 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1872 update_br_prob_note (basic_block bb)
1875 if (!JUMP_P (BB_END (bb)))
1877 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1878 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1880 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1883 /* Verify the CFG and RTL consistency common for both underlying RTL and
1886 Currently it does following checks:
1888 - test head/end pointers
1889 - overlapping of basic blocks
1890 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1891 - tails of basic blocks (ensure that boundary is necessary)
1892 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1893 and NOTE_INSN_BASIC_BLOCK
1894 - verify that no fall_thru edge crosses hot/cold partition boundaries
1896 In future it can be extended check a lot of other stuff as well
1897 (reachability of basic blocks, life information, etc. etc.). */
1900 rtl_verify_flow_info_1 (void)
1902 const int max_uid = get_max_uid ();
1903 rtx last_head = get_last_insn ();
1904 basic_block *bb_info;
1907 basic_block bb, last_bb_seen;
1909 bb_info = xcalloc (max_uid, sizeof (basic_block));
1911 /* Check bb chain & numbers. */
1912 last_bb_seen = ENTRY_BLOCK_PTR;
1914 FOR_EACH_BB_REVERSE (bb)
1916 rtx head = BB_HEAD (bb);
1917 rtx end = BB_END (bb);
1919 /* Verify the end of the basic block is in the INSN chain. */
1920 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1926 error ("end insn %d for block %d not found in the insn stream",
1927 INSN_UID (end), bb->index);
1931 /* Work backwards from the end to the head of the basic block
1932 to verify the head is in the RTL chain. */
1933 for (; x != NULL_RTX; x = PREV_INSN (x))
1935 /* While walking over the insn chain, verify insns appear
1936 in only one basic block and initialize the BB_INFO array
1937 used by other passes. */
1938 if (bb_info[INSN_UID (x)] != NULL)
1940 error ("insn %d is in multiple basic blocks (%d and %d)",
1941 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1945 bb_info[INSN_UID (x)] = bb;
1952 error ("head insn %d for block %d not found in the insn stream",
1953 INSN_UID (head), bb->index);
1960 /* Now check the basic blocks (boundaries etc.) */
1961 FOR_EACH_BB_REVERSE (bb)
1963 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1964 edge e, fallthru = NULL;
1967 if (INSN_P (BB_END (bb))
1968 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1969 && bb->succ && bb->succ->succ_next
1970 && any_condjump_p (BB_END (bb)))
1972 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1973 && profile_status != PROFILE_ABSENT)
1975 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1976 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1980 for (e = bb->succ; e; e = e->succ_next)
1982 if (e->flags & EDGE_FALLTHRU)
1984 n_fallthru++, fallthru = e;
1985 if ((e->flags & EDGE_CROSSING)
1986 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1987 && e->src != ENTRY_BLOCK_PTR
1988 && e->dest != EXIT_BLOCK_PTR))
1990 error ("Fallthru edge crosses section boundary (bb %i)",
1996 if ((e->flags & ~(EDGE_DFS_BACK
1998 | EDGE_IRREDUCIBLE_LOOP
2000 | EDGE_CROSSING)) == 0)
2003 if (e->flags & EDGE_ABNORMAL_CALL)
2006 if (e->flags & EDGE_EH)
2008 else if (e->flags & EDGE_ABNORMAL)
2012 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2013 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2015 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2019 && (!JUMP_P (BB_END (bb))
2020 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2021 || any_condjump_p (BB_END (bb))))))
2023 error ("Too many outgoing branch edges from bb %i", bb->index);
2026 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2028 error ("Fallthru edge after unconditional jump %i", bb->index);
2031 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2033 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2036 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2037 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2039 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2042 if (n_call && !CALL_P (BB_END (bb)))
2044 error ("Call edges for non-call insn in bb %i", bb->index);
2048 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2049 && (!JUMP_P (BB_END (bb))
2050 || any_condjump_p (BB_END (bb))
2051 || any_uncondjump_p (BB_END (bb))))
2053 error ("Abnormal edges for no purpose in bb %i", bb->index);
2057 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2058 if (BLOCK_FOR_INSN (x) != bb)
2061 if (! BLOCK_FOR_INSN (x))
2063 ("insn %d inside basic block %d but block_for_insn is NULL",
2064 INSN_UID (x), bb->index);
2067 ("insn %d inside basic block %d but block_for_insn is %i",
2068 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2073 /* OK pointers are correct. Now check the header of basic
2074 block. It ought to contain optional CODE_LABEL followed
2075 by NOTE_BASIC_BLOCK. */
2079 if (BB_END (bb) == x)
2081 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2089 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2091 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2096 if (BB_END (bb) == x)
2097 /* Do checks for empty blocks her. e */
2100 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2102 if (NOTE_INSN_BASIC_BLOCK_P (x))
2104 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2105 INSN_UID (x), bb->index);
2109 if (x == BB_END (bb))
2112 if (control_flow_insn_p (x))
2114 error ("in basic block %d:", bb->index);
2115 fatal_insn ("flow control insn inside a basic block", x);
2125 /* Verify the CFG and RTL consistency common for both underlying RTL and
2128 Currently it does following checks:
2129 - all checks of rtl_verify_flow_info_1
2130 - check that all insns are in the basic blocks
2131 (except the switch handling code, barriers and notes)
2132 - check that all returns are followed by barriers
2133 - check that all fallthru edge points to the adjacent blocks. */
2135 rtl_verify_flow_info (void)
2138 int err = rtl_verify_flow_info_1 ();
2141 const rtx rtx_first = get_insns ();
2142 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2144 FOR_EACH_BB_REVERSE (bb)
2147 for (e = bb->succ; e; e = e->succ_next)
2148 if (e->flags & EDGE_FALLTHRU)
2154 /* Ensure existence of barrier in BB with no fallthru edges. */
2155 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2156 insn = NEXT_INSN (insn))
2159 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2161 error ("missing barrier after block %i", bb->index);
2166 else if (e->src != ENTRY_BLOCK_PTR
2167 && e->dest != EXIT_BLOCK_PTR)
2171 if (e->src->next_bb != e->dest)
2174 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2175 e->src->index, e->dest->index);
2179 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2180 insn = NEXT_INSN (insn))
2181 if (BARRIER_P (insn)
2182 #ifndef CASE_DROPS_THROUGH
2185 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2189 error ("verify_flow_info: Incorrect fallthru %i->%i",
2190 e->src->index, e->dest->index);
2191 fatal_insn ("wrong insn in the fallthru edge", insn);
2198 last_bb_seen = ENTRY_BLOCK_PTR;
2200 for (x = rtx_first; x; x = NEXT_INSN (x))
2202 if (NOTE_INSN_BASIC_BLOCK_P (x))
2204 bb = NOTE_BASIC_BLOCK (x);
2207 if (bb != last_bb_seen->next_bb)
2208 internal_error ("basic blocks not laid down consecutively");
2210 curr_bb = last_bb_seen = bb;
2215 switch (GET_CODE (x))
2222 /* An addr_vec is placed outside any basic block. */
2224 && JUMP_P (NEXT_INSN (x))
2225 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2226 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2229 /* But in any case, non-deletable labels can appear anywhere. */
2233 fatal_insn ("insn outside basic block", x);
2239 && returnjump_p (x) && ! condjump_p (x)
2240 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2241 fatal_insn ("return not followed by barrier", x);
2242 if (curr_bb && x == BB_END (curr_bb))
2246 if (num_bb_notes != n_basic_blocks)
2248 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2249 num_bb_notes, n_basic_blocks);
2254 /* Assume that the preceding pass has possibly eliminated jump instructions
2255 or converted the unconditional jumps. Eliminate the edges from CFG.
2256 Return true if any edges are eliminated. */
2259 purge_dead_edges (basic_block bb)
2262 rtx insn = BB_END (bb), note;
2263 bool purged = false;
2265 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2266 if (NONJUMP_INSN_P (insn)
2267 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2271 if (! may_trap_p (PATTERN (insn))
2272 || ((eqnote = find_reg_equal_equiv_note (insn))
2273 && ! may_trap_p (XEXP (eqnote, 0))))
2274 remove_note (insn, note);
2277 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2278 for (e = bb->succ; e; e = next)
2280 next = e->succ_next;
2281 if (e->flags & EDGE_EH)
2283 if (can_throw_internal (BB_END (bb)))
2286 else if (e->flags & EDGE_ABNORMAL_CALL)
2288 if (CALL_P (BB_END (bb))
2289 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2290 || INTVAL (XEXP (note, 0)) >= 0))
2297 bb->flags |= BB_DIRTY;
2306 /* We do care only about conditional jumps and simplejumps. */
2307 if (!any_condjump_p (insn)
2308 && !returnjump_p (insn)
2309 && !simplejump_p (insn))
2312 /* Branch probability/prediction notes are defined only for
2313 condjumps. We've possibly turned condjump into simplejump. */
2314 if (simplejump_p (insn))
2316 note = find_reg_note (insn, REG_BR_PROB, NULL);
2318 remove_note (insn, note);
2319 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2320 remove_note (insn, note);
2323 for (e = bb->succ; e; e = next)
2325 next = e->succ_next;
2327 /* Avoid abnormal flags to leak from computed jumps turned
2328 into simplejumps. */
2330 e->flags &= ~EDGE_ABNORMAL;
2332 /* See if this edge is one we should keep. */
2333 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2334 /* A conditional jump can fall through into the next
2335 block, so we should keep the edge. */
2337 else if (e->dest != EXIT_BLOCK_PTR
2338 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2339 /* If the destination block is the target of the jump,
2342 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2343 /* If the destination block is the exit block, and this
2344 instruction is a return, then keep the edge. */
2346 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2347 /* Keep the edges that correspond to exceptions thrown by
2348 this instruction and rematerialize the EDGE_ABNORMAL
2349 flag we just cleared above. */
2351 e->flags |= EDGE_ABNORMAL;
2355 /* We do not need this edge. */
2356 bb->flags |= BB_DIRTY;
2361 if (!bb->succ || !purged)
2365 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2370 /* Redistribute probabilities. */
2371 if (!bb->succ->succ_next)
2373 bb->succ->probability = REG_BR_PROB_BASE;
2374 bb->succ->count = bb->count;
2378 note = find_reg_note (insn, REG_BR_PROB, NULL);
2382 b = BRANCH_EDGE (bb);
2383 f = FALLTHRU_EDGE (bb);
2384 b->probability = INTVAL (XEXP (note, 0));
2385 f->probability = REG_BR_PROB_BASE - b->probability;
2386 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2387 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2392 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2394 /* First, there should not be any EH or ABCALL edges resulting
2395 from non-local gotos and the like. If there were, we shouldn't
2396 have created the sibcall in the first place. Second, there
2397 should of course never have been a fallthru edge. */
2398 gcc_assert (bb->succ && !bb->succ->succ_next);
2399 gcc_assert (bb->succ->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2404 /* If we don't see a jump insn, we don't know exactly why the block would
2405 have been broken at this point. Look for a simple, non-fallthru edge,
2406 as these are only created by conditional branches. If we find such an
2407 edge we know that there used to be a jump here and can then safely
2408 remove all non-fallthru edges. */
2409 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
2416 for (e = bb->succ; e; e = next)
2418 next = e->succ_next;
2419 if (!(e->flags & EDGE_FALLTHRU))
2421 bb->flags |= BB_DIRTY;
2427 gcc_assert (bb->succ && !bb->succ->succ_next);
2429 bb->succ->probability = REG_BR_PROB_BASE;
2430 bb->succ->count = bb->count;
2433 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2438 /* Search all basic blocks for potentially dead edges and purge them. Return
2439 true if some edge has been eliminated. */
2442 purge_all_dead_edges (int update_life_p)
2450 blocks = sbitmap_alloc (last_basic_block);
2451 sbitmap_zero (blocks);
2456 bool purged_here = purge_dead_edges (bb);
2458 purged |= purged_here;
2459 if (purged_here && update_life_p)
2460 SET_BIT (blocks, bb->index);
2463 if (update_life_p && purged)
2464 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2465 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2466 | PROP_KILL_DEAD_CODE);
2469 sbitmap_free (blocks);
2473 /* Same as split_block but update cfg_layout structures. */
2476 cfg_layout_split_block (basic_block bb, void *insnp)
2479 basic_block new_bb = rtl_split_block (bb, insn);
2481 new_bb->rbi->footer = bb->rbi->footer;
2482 bb->rbi->footer = NULL;
2488 /* Redirect Edge to DEST. */
2490 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2492 basic_block src = e->src;
2495 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2498 if (e->dest == dest)
2501 if (e->src != ENTRY_BLOCK_PTR
2502 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2504 src->flags |= BB_DIRTY;
2508 if (e->src == ENTRY_BLOCK_PTR
2509 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2512 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2513 e->src->index, dest->index);
2515 e->src->flags |= BB_DIRTY;
2516 redirect_edge_succ (e, dest);
2520 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2521 in the case the basic block appears to be in sequence. Avoid this
2524 if (e->flags & EDGE_FALLTHRU)
2526 /* Redirect any branch edges unified with the fallthru one. */
2527 if (JUMP_P (BB_END (src))
2528 && label_is_jump_target_p (BB_HEAD (e->dest),
2534 fprintf (dump_file, "Fallthru edge unified with branch "
2535 "%i->%i redirected to %i\n",
2536 e->src->index, e->dest->index, dest->index);
2537 e->flags &= ~EDGE_FALLTHRU;
2538 redirected = redirect_branch_edge (e, dest);
2539 gcc_assert (redirected);
2540 e->flags |= EDGE_FALLTHRU;
2541 e->src->flags |= BB_DIRTY;
2544 /* In case we are redirecting fallthru edge to the branch edge
2545 of conditional jump, remove it. */
2546 if (src->succ->succ_next
2547 && !src->succ->succ_next->succ_next)
2549 edge s = e->succ_next ? e->succ_next : src->succ;
2551 && any_condjump_p (BB_END (src))
2552 && onlyjump_p (BB_END (src)))
2553 delete_insn (BB_END (src));
2555 ret = redirect_edge_succ_nodup (e, dest);
2557 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2558 e->src->index, e->dest->index, dest->index);
2561 ret = redirect_branch_edge (e, dest);
2563 /* We don't want simplejumps in the insn stream during cfglayout. */
2564 gcc_assert (!simplejump_p (BB_END (src)));
2566 src->flags |= BB_DIRTY;
2570 /* Simple wrapper as we always can redirect fallthru edges. */
2572 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2574 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2576 gcc_assert (redirected);
2580 /* Same as delete_basic_block but update cfg_layout structures. */
2583 cfg_layout_delete_block (basic_block bb)
2585 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2587 if (bb->rbi->header)
2589 next = BB_HEAD (bb);
2591 NEXT_INSN (prev) = bb->rbi->header;
2593 set_first_insn (bb->rbi->header);
2594 PREV_INSN (bb->rbi->header) = prev;
2595 insn = bb->rbi->header;
2596 while (NEXT_INSN (insn))
2597 insn = NEXT_INSN (insn);
2598 NEXT_INSN (insn) = next;
2599 PREV_INSN (next) = insn;
2601 next = NEXT_INSN (BB_END (bb));
2602 if (bb->rbi->footer)
2604 insn = bb->rbi->footer;
2607 if (BARRIER_P (insn))
2609 if (PREV_INSN (insn))
2610 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2612 bb->rbi->footer = NEXT_INSN (insn);
2613 if (NEXT_INSN (insn))
2614 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2618 insn = NEXT_INSN (insn);
2620 if (bb->rbi->footer)
2623 NEXT_INSN (insn) = bb->rbi->footer;
2624 PREV_INSN (bb->rbi->footer) = insn;
2625 while (NEXT_INSN (insn))
2626 insn = NEXT_INSN (insn);
2627 NEXT_INSN (insn) = next;
2629 PREV_INSN (next) = insn;
2631 set_last_insn (insn);
2634 if (bb->next_bb != EXIT_BLOCK_PTR)
2635 to = &bb->next_bb->rbi->header;
2637 to = &cfg_layout_function_footer;
2638 rtl_delete_block (bb);
2641 prev = NEXT_INSN (prev);
2643 prev = get_insns ();
2645 next = PREV_INSN (next);
2647 next = get_last_insn ();
2649 if (next && NEXT_INSN (next) != prev)
2651 remaints = unlink_insn_chain (prev, next);
2653 while (NEXT_INSN (insn))
2654 insn = NEXT_INSN (insn);
2655 NEXT_INSN (insn) = *to;
2657 PREV_INSN (*to) = insn;
2662 /* Return true when blocks A and B can be safely merged. */
2664 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2666 /* If we are partitioning hot/cold basic blocks, we don't want to
2667 mess up unconditional or indirect jumps that cross between hot
2670 Basic block partitioning may result in some jumps that appear to
2671 be optimizable (or blocks that appear to be mergeable), but which really
2672 must be left untouched (they are required to make it safely across
2673 partition boundaries). See the comments at the top of
2674 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2676 if (flag_reorder_blocks_and_partition
2677 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2678 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2679 || BB_PARTITION (a) != BB_PARTITION (b)))
2682 /* There must be exactly one edge in between the blocks. */
2683 return (a->succ && !a->succ->succ_next && a->succ->dest == b
2684 && !b->pred->pred_next && a != b
2685 /* Must be simple edge. */
2686 && !(a->succ->flags & EDGE_COMPLEX)
2687 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2688 /* If the jump insn has side effects,
2689 we can't kill the edge. */
2690 && (!JUMP_P (BB_END (a))
2691 || (reload_completed
2692 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2695 /* Merge block A and B, abort when it is not possible. */
2697 cfg_layout_merge_blocks (basic_block a, basic_block b)
2699 #ifdef ENABLE_CHECKING
2700 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2703 /* If there was a CODE_LABEL beginning B, delete it. */
2704 if (LABEL_P (BB_HEAD (b)))
2705 delete_insn (BB_HEAD (b));
2707 /* We should have fallthru edge in a, or we can do dummy redirection to get
2709 if (JUMP_P (BB_END (a)))
2710 try_redirect_by_replacing_jump (a->succ, b, true);
2711 gcc_assert (!JUMP_P (BB_END (a)));
2713 /* Possible line number notes should appear in between. */
2716 rtx first = BB_END (a), last;
2718 last = emit_insn_after (b->rbi->header, BB_END (a));
2719 delete_insn_chain (NEXT_INSN (first), last);
2720 b->rbi->header = NULL;
2723 /* In the case basic blocks are not adjacent, move them around. */
2724 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2726 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2728 emit_insn_after (first, BB_END (a));
2729 /* Skip possible DELETED_LABEL insn. */
2730 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2731 first = NEXT_INSN (first);
2732 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2734 delete_insn (first);
2736 /* Otherwise just re-associate the instructions. */
2741 for (insn = BB_HEAD (b);
2742 insn != NEXT_INSN (BB_END (b));
2743 insn = NEXT_INSN (insn))
2744 set_block_for_insn (insn, a);
2746 /* Skip possible DELETED_LABEL insn. */
2747 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2748 insn = NEXT_INSN (insn);
2749 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2751 BB_END (a) = BB_END (b);
2755 /* Possible tablejumps and barriers should appear after the block. */
2758 if (!a->rbi->footer)
2759 a->rbi->footer = b->rbi->footer;
2762 rtx last = a->rbi->footer;
2764 while (NEXT_INSN (last))
2765 last = NEXT_INSN (last);
2766 NEXT_INSN (last) = b->rbi->footer;
2767 PREV_INSN (b->rbi->footer) = last;
2769 b->rbi->footer = NULL;
2773 fprintf (dump_file, "Merged blocks %d and %d.\n",
2774 a->index, b->index);
2780 cfg_layout_split_edge (edge e)
2783 basic_block new_bb =
2784 create_basic_block (e->src != ENTRY_BLOCK_PTR
2785 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2788 /* ??? This info is likely going to be out of date very soon, but we must
2789 create it to avoid getting an ICE later. */
2790 if (e->dest->global_live_at_start)
2792 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2793 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2794 COPY_REG_SET (new_bb->global_live_at_start,
2795 e->dest->global_live_at_start);
2796 COPY_REG_SET (new_bb->global_live_at_end,
2797 e->dest->global_live_at_start);
2800 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2801 redirect_edge_and_branch_force (e, new_bb);
2806 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2809 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2813 /* Return 1 if BB ends with a call, possibly followed by some
2814 instructions that must stay with the call, 0 otherwise. */
2817 rtl_block_ends_with_call_p (basic_block bb)
2819 rtx insn = BB_END (bb);
2821 while (!CALL_P (insn)
2822 && insn != BB_HEAD (bb)
2823 && keep_with_call_p (insn))
2824 insn = PREV_INSN (insn);
2825 return (CALL_P (insn));
2828 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2831 rtl_block_ends_with_condjump_p (basic_block bb)
2833 return any_condjump_p (BB_END (bb));
2836 /* Return true if we need to add fake edge to exit.
2837 Helper function for rtl_flow_call_edges_add. */
2840 need_fake_edge_p (rtx insn)
2846 && !SIBLING_CALL_P (insn)
2847 && !find_reg_note (insn, REG_NORETURN, NULL)
2848 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2849 && !CONST_OR_PURE_CALL_P (insn)))
2852 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2853 && MEM_VOLATILE_P (PATTERN (insn)))
2854 || (GET_CODE (PATTERN (insn)) == PARALLEL
2855 && asm_noperands (insn) != -1
2856 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2857 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2860 /* Add fake edges to the function exit for any non constant and non noreturn
2861 calls, volatile inline assembly in the bitmap of blocks specified by
2862 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2865 The goal is to expose cases in which entering a basic block does not imply
2866 that all subsequent instructions must be executed. */
2869 rtl_flow_call_edges_add (sbitmap blocks)
2872 int blocks_split = 0;
2873 int last_bb = last_basic_block;
2874 bool check_last_block = false;
2876 if (n_basic_blocks == 0)
2880 check_last_block = true;
2882 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2884 /* In the last basic block, before epilogue generation, there will be
2885 a fallthru edge to EXIT. Special care is required if the last insn
2886 of the last basic block is a call because make_edge folds duplicate
2887 edges, which would result in the fallthru edge also being marked
2888 fake, which would result in the fallthru edge being removed by
2889 remove_fake_edges, which would result in an invalid CFG.
2891 Moreover, we can't elide the outgoing fake edge, since the block
2892 profiler needs to take this into account in order to solve the minimal
2893 spanning tree in the case that the call doesn't return.
2895 Handle this by adding a dummy instruction in a new last basic block. */
2896 if (check_last_block)
2898 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2899 rtx insn = BB_END (bb);
2901 /* Back up past insns that must be kept in the same block as a call. */
2902 while (insn != BB_HEAD (bb)
2903 && keep_with_call_p (insn))
2904 insn = PREV_INSN (insn);
2906 if (need_fake_edge_p (insn))
2910 for (e = bb->succ; e; e = e->succ_next)
2911 if (e->dest == EXIT_BLOCK_PTR)
2913 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2914 commit_edge_insertions ();
2920 /* Now add fake edges to the function exit for any non constant
2921 calls since there is no way that we can determine if they will
2924 for (i = 0; i < last_bb; i++)
2926 basic_block bb = BASIC_BLOCK (i);
2933 if (blocks && !TEST_BIT (blocks, i))
2936 for (insn = BB_END (bb); ; insn = prev_insn)
2938 prev_insn = PREV_INSN (insn);
2939 if (need_fake_edge_p (insn))
2942 rtx split_at_insn = insn;
2944 /* Don't split the block between a call and an insn that should
2945 remain in the same block as the call. */
2947 while (split_at_insn != BB_END (bb)
2948 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2949 split_at_insn = NEXT_INSN (split_at_insn);
2951 /* The handling above of the final block before the epilogue
2952 should be enough to verify that there is no edge to the exit
2953 block in CFG already. Calling make_edge in such case would
2954 cause us to mark that edge as fake and remove it later. */
2956 #ifdef ENABLE_CHECKING
2957 if (split_at_insn == BB_END (bb))
2958 for (e = bb->succ; e; e = e->succ_next)
2959 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2962 /* Note that the following may create a new basic block
2963 and renumber the existing basic blocks. */
2964 if (split_at_insn != BB_END (bb))
2966 e = split_block (bb, split_at_insn);
2971 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2974 if (insn == BB_HEAD (bb))
2980 verify_flow_info ();
2982 return blocks_split;
2985 /* Implementation of CFG manipulation for linearized RTL. */
2986 struct cfg_hooks rtl_cfg_hooks = {
2988 rtl_verify_flow_info,
2990 rtl_create_basic_block,
2991 rtl_redirect_edge_and_branch,
2992 rtl_redirect_edge_and_branch_force,
2995 rtl_move_block_after,
2996 rtl_can_merge_blocks, /* can_merge_blocks_p */
3000 NULL, /* can_duplicate_block_p */
3001 NULL, /* duplicate_block */
3003 rtl_make_forwarder_block,
3004 rtl_tidy_fallthru_edge,
3005 rtl_block_ends_with_call_p,
3006 rtl_block_ends_with_condjump_p,
3007 rtl_flow_call_edges_add
3010 /* Implementation of CFG manipulation for cfg layout RTL, where
3011 basic block connected via fallthru edges does not have to be adjacent.
3012 This representation will hopefully become the default one in future
3013 version of the compiler. */
3015 /* We do not want to declare these functions in a header file, since they
3016 should only be used through the cfghooks interface, and we do not want to
3017 move them here since it would require also moving quite a lot of related
3019 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3020 extern basic_block cfg_layout_duplicate_bb (basic_block);
3022 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3024 rtl_verify_flow_info_1,
3026 cfg_layout_create_basic_block,
3027 cfg_layout_redirect_edge_and_branch,
3028 cfg_layout_redirect_edge_and_branch_force,
3029 cfg_layout_delete_block,
3030 cfg_layout_split_block,
3031 rtl_move_block_after,
3032 cfg_layout_can_merge_blocks_p,
3033 cfg_layout_merge_blocks,
3036 cfg_layout_can_duplicate_bb_p,
3037 cfg_layout_duplicate_bb,
3038 cfg_layout_split_edge,
3039 rtl_make_forwarder_block,
3041 rtl_block_ends_with_call_p,
3042 rtl_block_ends_with_condjump_p,
3043 rtl_flow_call_edges_add