1 /* Control flow graph manipulation code for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 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 static int can_delete_note_p (rtx);
63 static int can_delete_label_p (rtx);
64 static void commit_one_edge_insertion (edge, int);
65 static rtx last_loop_beg_note (rtx);
66 static bool back_edge_of_syntactic_loop_p (basic_block, basic_block);
67 static basic_block rtl_split_edge (edge);
68 static bool rtl_move_block_after (basic_block, basic_block);
69 static int rtl_verify_flow_info (void);
70 static basic_block cfg_layout_split_block (basic_block, void *);
71 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
72 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
73 static void cfg_layout_delete_block (basic_block);
74 static void rtl_delete_block (basic_block);
75 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
76 static edge rtl_redirect_edge_and_branch (edge, basic_block);
77 static basic_block rtl_split_block (basic_block, void *);
78 static void rtl_dump_bb (basic_block, FILE *, int);
79 static int rtl_verify_flow_info_1 (void);
80 static void mark_killed_regs (rtx, rtx, void *);
81 static void rtl_make_forwarder_block (edge);
83 /* Return true if NOTE is not one of the ones that must be kept paired,
84 so that we may simply delete it. */
87 can_delete_note_p (rtx note)
89 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
90 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
93 /* True if a given label can be deleted. */
96 can_delete_label_p (rtx label)
98 return (!LABEL_PRESERVE_P (label)
99 /* User declared labels must be preserved. */
100 && LABEL_NAME (label) == 0
101 && !in_expr_list_p (forced_labels, label));
104 /* Delete INSN by patching it out. Return the next insn. */
107 delete_insn (rtx insn)
109 rtx next = NEXT_INSN (insn);
111 bool really_delete = true;
115 /* Some labels can't be directly removed from the INSN chain, as they
116 might be references via variables, constant pool etc.
117 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
118 if (! can_delete_label_p (insn))
120 const char *name = LABEL_NAME (insn);
122 really_delete = false;
123 PUT_CODE (insn, NOTE);
124 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
125 NOTE_DELETED_LABEL_NAME (insn) = name;
128 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
133 /* If this insn has already been deleted, something is very wrong. */
134 gcc_assert (!INSN_DELETED_P (insn));
136 INSN_DELETED_P (insn) = 1;
139 /* If deleting a jump, decrement the use count of the label. Deleting
140 the label itself should happen in the normal course of block merging. */
143 && LABEL_P (JUMP_LABEL (insn)))
144 LABEL_NUSES (JUMP_LABEL (insn))--;
146 /* Also if deleting an insn that references a label. */
149 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
150 && LABEL_P (XEXP (note, 0)))
152 LABEL_NUSES (XEXP (note, 0))--;
153 remove_note (insn, note);
158 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
159 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
161 rtx pat = PATTERN (insn);
162 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
163 int len = XVECLEN (pat, diff_vec_p);
166 for (i = 0; i < len; i++)
168 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
170 /* When deleting code in bulk (e.g. removing many unreachable
171 blocks) we can delete a label that's a target of the vector
172 before deleting the vector itself. */
174 LABEL_NUSES (label)--;
181 /* Like delete_insn but also purge dead edges from BB. */
183 delete_insn_and_edges (rtx insn)
189 && BLOCK_FOR_INSN (insn)
190 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
192 x = delete_insn (insn);
194 purge_dead_edges (BLOCK_FOR_INSN (insn));
198 /* Unlink a chain of insns between START and FINISH, leaving notes
199 that must be paired. */
202 delete_insn_chain (rtx start, rtx finish)
206 /* Unchain the insns one by one. It would be quicker to delete all of these
207 with a single unchaining, rather than one at a time, but we need to keep
211 next = NEXT_INSN (start);
212 if (NOTE_P (start) && !can_delete_note_p (start))
215 next = delete_insn (start);
223 /* Like delete_insn but also purge dead edges from BB. */
225 delete_insn_chain_and_edges (rtx first, rtx last)
230 && BLOCK_FOR_INSN (last)
231 && BB_END (BLOCK_FOR_INSN (last)) == last)
233 delete_insn_chain (first, last);
235 purge_dead_edges (BLOCK_FOR_INSN (last));
238 /* Create a new basic block consisting of the instructions between HEAD and END
239 inclusive. This function is designed to allow fast BB construction - reuses
240 the note and basic block struct in BB_NOTE, if any and do not grow
241 BASIC_BLOCK chain and should be used directly only by CFG construction code.
242 END can be NULL in to create new empty basic block before HEAD. Both END
243 and HEAD can be NULL to create basic block at the end of INSN chain.
244 AFTER is the basic block we should be put after. */
247 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
252 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
255 /* If we found an existing note, thread it back onto the chain. */
263 after = PREV_INSN (head);
267 if (after != bb_note && NEXT_INSN (after) != bb_note)
268 reorder_insns_nobb (bb_note, bb_note, after);
272 /* Otherwise we must create a note and a basic block structure. */
278 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
279 else if (LABEL_P (head) && end)
281 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
287 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
293 NOTE_BASIC_BLOCK (bb_note) = bb;
296 /* Always include the bb note in the block. */
297 if (NEXT_INSN (end) == bb_note)
302 bb->index = last_basic_block++;
304 link_block (bb, after);
305 BASIC_BLOCK (bb->index) = bb;
306 update_bb_for_insn (bb);
307 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
309 /* Tag the block so that we know it has been used when considering
310 other basic block notes. */
316 /* Create new basic block consisting of instructions in between HEAD and END
317 and place it to the BB chain after block AFTER. END can be NULL in to
318 create new empty basic block before HEAD. Both END and HEAD can be NULL to
319 create basic block at the end of INSN chain. */
322 rtl_create_basic_block (void *headp, void *endp, basic_block after)
324 rtx head = headp, end = endp;
327 /* Grow the basic block array if needed. */
328 if ((size_t) last_basic_block >= VARRAY_SIZE (basic_block_info))
330 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
331 VARRAY_GROW (basic_block_info, new_size);
336 bb = create_basic_block_structure (head, end, NULL, after);
342 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
344 basic_block newbb = rtl_create_basic_block (head, end, after);
346 initialize_bb_rbi (newbb);
350 /* Delete the insns in a (non-live) block. We physically delete every
351 non-deleted-note insn, and update the flow graph appropriately.
353 Return nonzero if we deleted an exception handler. */
355 /* ??? Preserving all such notes strikes me as wrong. It would be nice
356 to post-process the stream to remove empty blocks, loops, ranges, etc. */
359 rtl_delete_block (basic_block b)
363 /* If the head of this block is a CODE_LABEL, then it might be the
364 label for an exception handler which can't be reached. We need
365 to remove the label from the exception_handler_label list. */
368 maybe_remove_eh_handler (insn);
370 /* Include any jump table following the basic block. */
372 if (tablejump_p (end, NULL, &tmp))
375 /* Include any barriers that may follow the basic block. */
376 tmp = next_nonnote_insn (end);
377 while (tmp && BARRIER_P (tmp))
380 tmp = next_nonnote_insn (end);
383 /* Selectively delete the entire chain. */
385 delete_insn_chain (insn, end);
388 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
391 compute_bb_for_insn (void)
397 rtx end = BB_END (bb);
400 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
402 BLOCK_FOR_INSN (insn) = bb;
409 /* Release the basic_block_for_insn array. */
412 free_bb_for_insn (void)
415 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
416 if (!BARRIER_P (insn))
417 BLOCK_FOR_INSN (insn) = NULL;
420 /* Return RTX to emit after when we want to emit code on the entry of function. */
422 entry_of_function (void)
424 return (n_basic_blocks ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
427 /* Update insns block within BB. */
430 update_bb_for_insn (basic_block bb)
434 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
436 if (!BARRIER_P (insn))
437 set_block_for_insn (insn, bb);
438 if (insn == BB_END (bb))
443 /* Creates a new basic block just after basic block B by splitting
444 everything after specified instruction I. */
447 rtl_split_block (basic_block bb, void *insnp)
456 insn = first_insn_after_basic_block_note (bb);
459 insn = PREV_INSN (insn);
461 insn = get_last_insn ();
464 /* We probably should check type of the insn so that we do not create
465 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
467 if (insn == BB_END (bb))
468 emit_note_after (NOTE_INSN_DELETED, insn);
470 /* Create the new basic block. */
471 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
472 BB_COPY_PARTITION (new_bb, bb);
475 /* Redirect the outgoing edges. */
476 new_bb->succs = bb->succs;
478 FOR_EACH_EDGE (e, ei, new_bb->succs)
481 if (bb->global_live_at_start)
483 new_bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
484 new_bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
485 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
487 /* We now have to calculate which registers are live at the end
488 of the split basic block and at the start of the new basic
489 block. Start with those registers that are known to be live
490 at the end of the original basic block and get
491 propagate_block to determine which registers are live. */
492 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
493 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
494 COPY_REG_SET (bb->global_live_at_end,
495 new_bb->global_live_at_start);
496 #ifdef HAVE_conditional_execution
497 /* In the presence of conditional execution we are not able to update
498 liveness precisely. */
499 if (reload_completed)
501 bb->flags |= BB_DIRTY;
502 new_bb->flags |= BB_DIRTY;
510 /* Blocks A and B are to be merged into a single block A. The insns
511 are already contiguous. */
514 rtl_merge_blocks (basic_block a, basic_block b)
516 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
517 rtx del_first = NULL_RTX, del_last = NULL_RTX;
520 /* If there was a CODE_LABEL beginning B, delete it. */
521 if (LABEL_P (b_head))
523 /* Detect basic blocks with nothing but a label. This can happen
524 in particular at the end of a function. */
528 del_first = del_last = b_head;
529 b_head = NEXT_INSN (b_head);
532 /* Delete the basic block note and handle blocks containing just that
534 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
542 b_head = NEXT_INSN (b_head);
545 /* If there was a jump out of A, delete it. */
550 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
552 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
553 || prev == BB_HEAD (a))
559 /* If this was a conditional jump, we need to also delete
560 the insn that set cc0. */
561 if (only_sets_cc0_p (prev))
565 prev = prev_nonnote_insn (prev);
572 a_end = PREV_INSN (del_first);
574 else if (BARRIER_P (NEXT_INSN (a_end)))
575 del_first = NEXT_INSN (a_end);
577 /* Delete everything marked above as well as crap that might be
578 hanging out between the two blocks. */
580 delete_insn_chain (del_first, del_last);
582 /* Reassociate the insns of B with A. */
587 for (x = a_end; x != b_end; x = NEXT_INSN (x))
588 set_block_for_insn (x, a);
590 set_block_for_insn (b_end, a);
598 /* Return true when block A and B can be merged. */
600 rtl_can_merge_blocks (basic_block a,basic_block b)
602 /* If we are partitioning hot/cold basic blocks, we don't want to
603 mess up unconditional or indirect jumps that cross between hot
606 Basic block partitioning may result in some jumps that appear to
607 be optimizable (or blocks that appear to be mergeable), but which really
608 must be left untouched (they are required to make it safely across
609 partition boundaries). See the comments at the top of
610 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
612 if (BB_PARTITION (a) != BB_PARTITION (b))
615 /* There must be exactly one edge in between the blocks. */
616 return (single_succ_p (a)
617 && single_succ (a) == b
620 /* Must be simple edge. */
621 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
623 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
624 /* If the jump insn has side effects,
625 we can't kill the edge. */
626 && (!JUMP_P (BB_END (a))
628 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
631 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
635 block_label (basic_block block)
637 if (block == EXIT_BLOCK_PTR)
640 if (!LABEL_P (BB_HEAD (block)))
642 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
645 return BB_HEAD (block);
648 /* Attempt to perform edge redirection by replacing possibly complex jump
649 instruction by unconditional jump or removing jump completely. This can
650 apply only if all edges now point to the same block. The parameters and
651 return values are equivalent to redirect_edge_and_branch. */
654 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
656 basic_block src = e->src;
657 rtx insn = BB_END (src), kill_from;
661 /* If we are partitioning hot/cold basic blocks, we don't want to
662 mess up unconditional or indirect jumps that cross between hot
665 Basic block partitioning may result in some jumps that appear to
666 be optimizable (or blocks that appear to be mergeable), but which really
667 must be left untouched (they are required to make it safely across
668 partition boundaries). See the comments at the top of
669 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
671 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
672 || BB_PARTITION (src) != BB_PARTITION (target))
675 /* We can replace or remove a complex jump only when we have exactly
676 two edges. Also, if we have exactly one outgoing edge, we can
678 if (EDGE_COUNT (src->succs) >= 3
679 /* Verify that all targets will be TARGET. Specifically, the
680 edge that is not E must also go to TARGET. */
681 || (EDGE_COUNT (src->succs) == 2
682 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
685 if (!onlyjump_p (insn))
687 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
690 /* Avoid removing branch with side effects. */
691 set = single_set (insn);
692 if (!set || side_effects_p (set))
695 /* In case we zap a conditional jump, we'll need to kill
696 the cc0 setter too. */
699 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
700 kill_from = PREV_INSN (insn);
703 /* See if we can create the fallthru edge. */
704 if (in_cfglayout || can_fallthru (src, target))
707 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
710 /* Selectively unlink whole insn chain. */
713 rtx insn = src->rbi->footer;
715 delete_insn_chain (kill_from, BB_END (src));
717 /* Remove barriers but keep jumptables. */
720 if (BARRIER_P (insn))
722 if (PREV_INSN (insn))
723 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
725 src->rbi->footer = NEXT_INSN (insn);
726 if (NEXT_INSN (insn))
727 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
731 insn = NEXT_INSN (insn);
735 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
738 /* If this already is simplejump, redirect it. */
739 else if (simplejump_p (insn))
741 if (e->dest == target)
744 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
745 INSN_UID (insn), e->dest->index, target->index);
746 if (!redirect_jump (insn, block_label (target), 0))
748 gcc_assert (target == EXIT_BLOCK_PTR);
753 /* Cannot do anything for target exit block. */
754 else if (target == EXIT_BLOCK_PTR)
757 /* Or replace possibly complicated jump insn by simple jump insn. */
760 rtx target_label = block_label (target);
761 rtx barrier, label, table;
763 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
764 JUMP_LABEL (BB_END (src)) = target_label;
765 LABEL_NUSES (target_label)++;
767 fprintf (dump_file, "Replacing insn %i by jump %i\n",
768 INSN_UID (insn), INSN_UID (BB_END (src)));
771 delete_insn_chain (kill_from, insn);
773 /* Recognize a tablejump that we are converting to a
774 simple jump and remove its associated CODE_LABEL
775 and ADDR_VEC or ADDR_DIFF_VEC. */
776 if (tablejump_p (insn, &label, &table))
777 delete_insn_chain (label, table);
779 barrier = next_nonnote_insn (BB_END (src));
780 if (!barrier || !BARRIER_P (barrier))
781 emit_barrier_after (BB_END (src));
784 if (barrier != NEXT_INSN (BB_END (src)))
786 /* Move the jump before barrier so that the notes
787 which originally were or were created before jump table are
788 inside the basic block. */
789 rtx new_insn = BB_END (src);
792 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
793 tmp = NEXT_INSN (tmp))
794 set_block_for_insn (tmp, src);
796 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
797 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
799 NEXT_INSN (new_insn) = barrier;
800 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
802 PREV_INSN (new_insn) = PREV_INSN (barrier);
803 PREV_INSN (barrier) = new_insn;
808 /* Keep only one edge out and set proper flags. */
809 if (!single_succ_p (src))
811 gcc_assert (single_succ_p (src));
813 e = single_succ_edge (src);
815 e->flags = EDGE_FALLTHRU;
819 e->probability = REG_BR_PROB_BASE;
820 e->count = src->count;
822 /* We don't want a block to end on a line-number note since that has
823 the potential of changing the code between -g and not -g. */
824 while (NOTE_P (BB_END (e->src))
825 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
826 delete_insn (BB_END (e->src));
828 if (e->dest != target)
829 redirect_edge_succ (e, target);
834 /* Return last loop_beg note appearing after INSN, before start of next
835 basic block. Return INSN if there are no such notes.
837 When emitting jump to redirect a fallthru edge, it should always appear
838 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
839 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
843 last_loop_beg_note (rtx insn)
847 for (insn = NEXT_INSN (insn); insn && NOTE_P (insn)
848 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
849 insn = NEXT_INSN (insn))
850 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
856 /* Redirect edge representing branch of (un)conditional jump or tablejump,
859 redirect_branch_edge (edge e, basic_block target)
862 rtx old_label = BB_HEAD (e->dest);
863 basic_block src = e->src;
864 rtx insn = BB_END (src);
866 /* We can only redirect non-fallthru edges of jump insn. */
867 if (e->flags & EDGE_FALLTHRU)
869 else if (!JUMP_P (insn))
872 /* Recognize a tablejump and adjust all matching cases. */
873 if (tablejump_p (insn, NULL, &tmp))
877 rtx new_label = block_label (target);
879 if (target == EXIT_BLOCK_PTR)
881 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
882 vec = XVEC (PATTERN (tmp), 0);
884 vec = XVEC (PATTERN (tmp), 1);
886 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
887 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
889 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
890 --LABEL_NUSES (old_label);
891 ++LABEL_NUSES (new_label);
894 /* Handle casesi dispatch insns. */
895 if ((tmp = single_set (insn)) != NULL
896 && SET_DEST (tmp) == pc_rtx
897 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
898 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
899 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
901 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
903 --LABEL_NUSES (old_label);
904 ++LABEL_NUSES (new_label);
909 /* ?? We may play the games with moving the named labels from
910 one basic block to the other in case only one computed_jump is
912 if (computed_jump_p (insn)
913 /* A return instruction can't be redirected. */
914 || returnjump_p (insn))
917 /* If the insn doesn't go where we think, we're confused. */
918 gcc_assert (JUMP_LABEL (insn) == old_label);
920 /* If the substitution doesn't succeed, die. This can happen
921 if the back end emitted unrecognizable instructions or if
922 target is exit block on some arches. */
923 if (!redirect_jump (insn, block_label (target), 0))
925 gcc_assert (target == EXIT_BLOCK_PTR);
931 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
932 e->src->index, e->dest->index, target->index);
934 if (e->dest != target)
935 e = redirect_edge_succ_nodup (e, target);
939 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
940 expense of adding new instructions or reordering basic blocks.
942 Function can be also called with edge destination equivalent to the TARGET.
943 Then it should try the simplifications and do nothing if none is possible.
945 Return edge representing the branch if transformation succeeded. Return NULL
947 We still return NULL in case E already destinated TARGET and we didn't
948 managed to simplify instruction stream. */
951 rtl_redirect_edge_and_branch (edge e, basic_block target)
954 basic_block src = e->src;
956 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
959 if (e->dest == target)
962 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
964 src->flags |= BB_DIRTY;
968 ret = redirect_branch_edge (e, target);
972 src->flags |= BB_DIRTY;
976 /* Like force_nonfallthru below, but additionally performs redirection
977 Used by redirect_edge_and_branch_force. */
980 force_nonfallthru_and_redirect (edge e, basic_block target)
982 basic_block jump_block, new_bb = NULL, src = e->src;
985 int abnormal_edge_flags = 0;
987 /* In the case the last instruction is conditional jump to the next
988 instruction, first redirect the jump itself and then continue
989 by creating a basic block afterwards to redirect fallthru edge. */
990 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
991 && any_condjump_p (BB_END (e->src))
992 /* When called from cfglayout, fallthru edges do not
993 necessarily go to the next block. */
994 && e->src->next_bb == e->dest
995 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
998 edge b = unchecked_make_edge (e->src, target, 0);
1001 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1002 gcc_assert (redirected);
1004 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1007 int prob = INTVAL (XEXP (note, 0));
1009 b->probability = prob;
1010 b->count = e->count * prob / REG_BR_PROB_BASE;
1011 e->probability -= e->probability;
1012 e->count -= b->count;
1013 if (e->probability < 0)
1020 if (e->flags & EDGE_ABNORMAL)
1022 /* Irritating special case - fallthru edge to the same block as abnormal
1024 We can't redirect abnormal edge, but we still can split the fallthru
1025 one and create separate abnormal edge to original destination.
1026 This allows bb-reorder to make such edge non-fallthru. */
1027 gcc_assert (e->dest == target);
1028 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1029 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1033 gcc_assert (e->flags & EDGE_FALLTHRU);
1034 if (e->src == ENTRY_BLOCK_PTR)
1036 /* We can't redirect the entry block. Create an empty block
1037 at the start of the function which we use to add the new
1043 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1045 /* Change the existing edge's source to be the new block, and add
1046 a new edge from the entry block to the new block. */
1048 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1052 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1062 VEC_safe_push (edge, gc, bb->succs, e);
1063 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1067 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1069 /* Create the new structures. */
1071 /* If the old block ended with a tablejump, skip its table
1072 by searching forward from there. Otherwise start searching
1073 forward from the last instruction of the old block. */
1074 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1075 note = BB_END (e->src);
1077 /* Position the new block correctly relative to loop notes. */
1078 note = last_loop_beg_note (note);
1079 note = NEXT_INSN (note);
1081 jump_block = create_basic_block (note, NULL, e->src);
1082 jump_block->count = e->count;
1083 jump_block->frequency = EDGE_FREQUENCY (e);
1084 jump_block->loop_depth = target->loop_depth;
1086 if (target->global_live_at_start)
1088 jump_block->global_live_at_start = ALLOC_REG_SET (®_obstack);
1089 jump_block->global_live_at_end = ALLOC_REG_SET (®_obstack);
1090 COPY_REG_SET (jump_block->global_live_at_start,
1091 target->global_live_at_start);
1092 COPY_REG_SET (jump_block->global_live_at_end,
1093 target->global_live_at_start);
1096 /* Make sure new block ends up in correct hot/cold section. */
1098 BB_COPY_PARTITION (jump_block, e->src);
1099 if (flag_reorder_blocks_and_partition
1100 && targetm.have_named_sections
1101 && JUMP_P (BB_END (jump_block))
1102 && !any_condjump_p (BB_END (jump_block))
1103 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1104 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP,
1111 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1112 new_edge->probability = e->probability;
1113 new_edge->count = e->count;
1115 /* Redirect old edge. */
1116 redirect_edge_pred (e, jump_block);
1117 e->probability = REG_BR_PROB_BASE;
1119 new_bb = jump_block;
1122 jump_block = e->src;
1124 e->flags &= ~EDGE_FALLTHRU;
1125 if (target == EXIT_BLOCK_PTR)
1128 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1135 rtx label = block_label (target);
1136 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1137 JUMP_LABEL (BB_END (jump_block)) = label;
1138 LABEL_NUSES (label)++;
1141 emit_barrier_after (BB_END (jump_block));
1142 redirect_edge_succ_nodup (e, target);
1144 if (abnormal_edge_flags)
1145 make_edge (src, target, abnormal_edge_flags);
1150 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1151 (and possibly create new basic block) to make edge non-fallthru.
1152 Return newly created BB or NULL if none. */
1155 force_nonfallthru (edge e)
1157 return force_nonfallthru_and_redirect (e, e->dest);
1160 /* Redirect edge even at the expense of creating new jump insn or
1161 basic block. Return new basic block if created, NULL otherwise.
1162 Conversion must be possible. */
1165 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1167 if (redirect_edge_and_branch (e, target)
1168 || e->dest == target)
1171 /* In case the edge redirection failed, try to force it to be non-fallthru
1172 and redirect newly created simplejump. */
1173 return force_nonfallthru_and_redirect (e, target);
1176 /* The given edge should potentially be a fallthru edge. If that is in
1177 fact true, delete the jump and barriers that are in the way. */
1180 rtl_tidy_fallthru_edge (edge e)
1183 basic_block b = e->src, c = b->next_bb;
1185 /* ??? In a late-running flow pass, other folks may have deleted basic
1186 blocks by nopping out blocks, leaving multiple BARRIERs between here
1187 and the target label. They ought to be chastised and fixed.
1189 We can also wind up with a sequence of undeletable labels between
1190 one block and the next.
1192 So search through a sequence of barriers, labels, and notes for
1193 the head of block C and assert that we really do fall through. */
1195 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1199 /* Remove what will soon cease being the jump insn from the source block.
1200 If block B consisted only of this single jump, turn it into a deleted
1205 && (any_uncondjump_p (q)
1206 || single_succ_p (b)))
1209 /* If this was a conditional jump, we need to also delete
1210 the insn that set cc0. */
1211 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1217 /* We don't want a block to end on a line-number note since that has
1218 the potential of changing the code between -g and not -g. */
1219 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1223 /* Selectively unlink the sequence. */
1224 if (q != PREV_INSN (BB_HEAD (c)))
1225 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1227 e->flags |= EDGE_FALLTHRU;
1230 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1231 is back edge of syntactic loop. */
1234 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1243 /* ??? Could we guarantee that bb indices are monotone, so that we could
1244 just compare them? */
1245 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1251 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1252 insn = NEXT_INSN (insn))
1255 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1257 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1264 /* Should move basic block BB after basic block AFTER. NIY. */
1267 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1268 basic_block after ATTRIBUTE_UNUSED)
1273 /* Split a (typically critical) edge. Return the new block.
1274 The edge must not be abnormal.
1276 ??? The code generally expects to be called on critical edges.
1277 The case of a block ending in an unconditional jump to a
1278 block with multiple predecessors is not handled optimally. */
1281 rtl_split_edge (edge edge_in)
1286 /* Abnormal edges cannot be split. */
1287 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1289 /* We are going to place the new block in front of edge destination.
1290 Avoid existence of fallthru predecessors. */
1291 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1296 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1297 if (e->flags & EDGE_FALLTHRU)
1301 force_nonfallthru (e);
1304 /* Create the basic block note.
1306 Where we place the note can have a noticeable impact on the generated
1307 code. Consider this cfg:
1317 If we need to insert an insn on the edge from block 0 to block 1,
1318 we want to ensure the instructions we insert are outside of any
1319 loop notes that physically sit between block 0 and block 1. Otherwise
1320 we confuse the loop optimizer into thinking the loop is a phony. */
1322 if (edge_in->dest != EXIT_BLOCK_PTR
1323 && PREV_INSN (BB_HEAD (edge_in->dest))
1324 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1325 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1326 == NOTE_INSN_LOOP_BEG)
1327 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1328 before = PREV_INSN (BB_HEAD (edge_in->dest));
1329 else if (edge_in->dest != EXIT_BLOCK_PTR)
1330 before = BB_HEAD (edge_in->dest);
1334 /* If this is a fall through edge to the exit block, the blocks might be
1335 not adjacent, and the right place is the after the source. */
1336 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1338 before = NEXT_INSN (BB_END (edge_in->src));
1341 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1342 before = NEXT_INSN (before);
1343 bb = create_basic_block (before, NULL, edge_in->src);
1344 BB_COPY_PARTITION (bb, edge_in->src);
1348 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1349 /* ??? Why not edge_in->dest->prev_bb here? */
1350 BB_COPY_PARTITION (bb, edge_in->dest);
1353 /* ??? This info is likely going to be out of date very soon. */
1354 if (edge_in->dest->global_live_at_start)
1356 bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
1357 bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
1358 COPY_REG_SET (bb->global_live_at_start,
1359 edge_in->dest->global_live_at_start);
1360 COPY_REG_SET (bb->global_live_at_end,
1361 edge_in->dest->global_live_at_start);
1364 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1366 /* For non-fallthru edges, we must adjust the predecessor's
1367 jump instruction to target our new block. */
1368 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1370 edge redirected = redirect_edge_and_branch (edge_in, bb);
1371 gcc_assert (redirected);
1374 redirect_edge_succ (edge_in, bb);
1379 /* Queue instructions for insertion on an edge between two basic blocks.
1380 The new instructions and basic blocks (if any) will not appear in the
1381 CFG until commit_edge_insertions is called. */
1384 insert_insn_on_edge (rtx pattern, edge e)
1386 /* We cannot insert instructions on an abnormal critical edge.
1387 It will be easier to find the culprit if we die now. */
1388 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1390 if (e->insns.r == NULL_RTX)
1393 push_to_sequence (e->insns.r);
1395 emit_insn (pattern);
1397 e->insns.r = get_insns ();
1401 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1402 registers that are killed by the store. */
1404 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1406 regset killed = data;
1409 if (GET_CODE (reg) == SUBREG)
1410 reg = SUBREG_REG (reg);
1413 regno = REGNO (reg);
1414 if (regno >= FIRST_PSEUDO_REGISTER)
1415 SET_REGNO_REG_SET (killed, regno);
1418 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1419 SET_REGNO_REG_SET (killed, regno + i);
1423 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1424 it checks whether this will not clobber the registers that are live on the
1425 edge (i.e. it requires liveness information to be up-to-date) and if there
1426 are some, then it tries to save and restore them. Returns true if
1429 safe_insert_insn_on_edge (rtx insn, edge e)
1433 rtx save_regs = NULL_RTX;
1436 enum machine_mode mode;
1437 reg_set_iterator rsi;
1439 #ifdef AVOID_CCMODE_COPIES
1445 killed = ALLOC_REG_SET (®_obstack);
1447 for (x = insn; x; x = NEXT_INSN (x))
1449 note_stores (PATTERN (x), mark_killed_regs, killed);
1451 /* Mark all hard registers as killed. Register allocator/reload cannot
1452 cope with the situation when life range of hard register spans operation
1453 for that the appropriate register is needed, i.e. it would be unsafe to
1454 extend the life ranges of hard registers. */
1455 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
1456 if (!fixed_regs[regno]
1457 && !REGNO_PTR_FRAME_P (regno))
1458 SET_REGNO_REG_SET (killed, regno);
1460 bitmap_and_into (killed, e->dest->global_live_at_start);
1462 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno, rsi)
1464 mode = regno < FIRST_PSEUDO_REGISTER
1465 ? reg_raw_mode[regno]
1466 : GET_MODE (regno_reg_rtx[regno]);
1467 if (mode == VOIDmode)
1470 if (noccmode && mode == CCmode)
1473 save_regs = alloc_EXPR_LIST (0,
1476 gen_raw_REG (mode, regno)),
1485 for (x = save_regs; x; x = XEXP (x, 1))
1487 from = XEXP (XEXP (x, 0), 1);
1488 to = XEXP (XEXP (x, 0), 0);
1489 emit_move_insn (to, from);
1492 for (x = save_regs; x; x = XEXP (x, 1))
1494 from = XEXP (XEXP (x, 0), 0);
1495 to = XEXP (XEXP (x, 0), 1);
1496 emit_move_insn (to, from);
1498 insn = get_insns ();
1500 free_EXPR_LIST_list (&save_regs);
1502 insert_insn_on_edge (insn, e);
1504 FREE_REG_SET (killed);
1509 /* Update the CFG for the instructions queued on edge E. */
1512 commit_one_edge_insertion (edge e, int watch_calls)
1514 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1515 basic_block bb = NULL;
1517 /* Pull the insns off the edge now since the edge might go away. */
1519 e->insns.r = NULL_RTX;
1521 /* Special case -- avoid inserting code between call and storing
1522 its return value. */
1523 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1524 && single_pred_p (e->dest)
1525 && e->src != ENTRY_BLOCK_PTR
1526 && CALL_P (BB_END (e->src)))
1528 rtx next = next_nonnote_insn (BB_END (e->src));
1530 after = BB_HEAD (e->dest);
1531 /* The first insn after the call may be a stack pop, skip it. */
1533 && keep_with_call_p (next))
1536 next = next_nonnote_insn (next);
1540 if (!before && !after)
1542 /* Figure out where to put these things. If the destination has
1543 one predecessor, insert there. Except for the exit block. */
1544 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1548 /* Get the location correct wrt a code label, and "nice" wrt
1549 a basic block note, and before everything else. */
1552 tmp = NEXT_INSN (tmp);
1553 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1554 tmp = NEXT_INSN (tmp);
1555 if (tmp == BB_HEAD (bb))
1558 after = PREV_INSN (tmp);
1560 after = get_last_insn ();
1563 /* If the source has one successor and the edge is not abnormal,
1564 insert there. Except for the entry block. */
1565 else if ((e->flags & EDGE_ABNORMAL) == 0
1566 && single_succ_p (e->src)
1567 && e->src != ENTRY_BLOCK_PTR)
1571 /* It is possible to have a non-simple jump here. Consider a target
1572 where some forms of unconditional jumps clobber a register. This
1573 happens on the fr30 for example.
1575 We know this block has a single successor, so we can just emit
1576 the queued insns before the jump. */
1577 if (JUMP_P (BB_END (bb)))
1578 for (before = BB_END (bb);
1579 NOTE_P (PREV_INSN (before))
1580 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1581 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1585 /* We'd better be fallthru, or we've lost track of
1587 gcc_assert (e->flags & EDGE_FALLTHRU);
1589 after = BB_END (bb);
1592 /* Otherwise we must split the edge. */
1595 bb = split_edge (e);
1596 after = BB_END (bb);
1598 if (flag_reorder_blocks_and_partition
1599 && targetm.have_named_sections
1600 && e->src != ENTRY_BLOCK_PTR
1601 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1602 && !(e->flags & EDGE_CROSSING))
1604 rtx bb_note, cur_insn;
1607 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1608 cur_insn = NEXT_INSN (cur_insn))
1609 if (NOTE_P (cur_insn)
1610 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1616 if (JUMP_P (BB_END (bb))
1617 && !any_condjump_p (BB_END (bb))
1618 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1619 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1620 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1625 /* Now that we've found the spot, do the insertion. */
1629 emit_insn_before_noloc (insns, before);
1630 last = prev_nonnote_insn (before);
1633 last = emit_insn_after_noloc (insns, after);
1635 if (returnjump_p (last))
1637 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1638 This is not currently a problem because this only happens
1639 for the (single) epilogue, which already has a fallthru edge
1642 e = single_succ_edge (bb);
1643 gcc_assert (e->dest == EXIT_BLOCK_PTR
1644 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1646 e->flags &= ~EDGE_FALLTHRU;
1647 emit_barrier_after (last);
1650 delete_insn (before);
1653 gcc_assert (!JUMP_P (last));
1655 /* Mark the basic block for find_many_sub_basic_blocks. */
1659 /* Update the CFG for all queued instructions. */
1662 commit_edge_insertions (void)
1666 bool changed = false;
1668 #ifdef ENABLE_CHECKING
1669 verify_flow_info ();
1672 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1677 FOR_EACH_EDGE (e, ei, bb->succs)
1681 commit_one_edge_insertion (e, false);
1688 blocks = sbitmap_alloc (last_basic_block);
1689 sbitmap_zero (blocks);
1693 SET_BIT (blocks, bb->index);
1694 /* Check for forgotten bb->aux values before commit_edge_insertions
1696 gcc_assert (bb->aux == &bb->aux);
1699 find_many_sub_basic_blocks (blocks);
1700 sbitmap_free (blocks);
1703 /* Update the CFG for all queued instructions, taking special care of inserting
1704 code on edges between call and storing its return value. */
1707 commit_edge_insertions_watch_calls (void)
1711 bool changed = false;
1713 #ifdef ENABLE_CHECKING
1714 verify_flow_info ();
1717 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1722 FOR_EACH_EDGE (e, ei, bb->succs)
1726 commit_one_edge_insertion (e, true);
1733 blocks = sbitmap_alloc (last_basic_block);
1734 sbitmap_zero (blocks);
1738 SET_BIT (blocks, bb->index);
1739 /* Check for forgotten bb->aux values before commit_edge_insertions
1741 gcc_assert (bb->aux == &bb->aux);
1744 find_many_sub_basic_blocks (blocks);
1745 sbitmap_free (blocks);
1748 /* Print out RTL-specific basic block information (live information
1749 at start and end). */
1752 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1758 s_indent = alloca ((size_t) indent + 1);
1759 memset (s_indent, ' ', (size_t) indent);
1760 s_indent[indent] = '\0';
1762 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1763 dump_regset (bb->global_live_at_start, outf);
1766 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1767 insn = NEXT_INSN (insn))
1768 print_rtl_single (outf, insn);
1770 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1771 dump_regset (bb->global_live_at_end, outf);
1775 /* Like print_rtl, but also print out live information for the start of each
1779 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1784 fprintf (outf, "(nil)\n");
1787 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1788 int max_uid = get_max_uid ();
1789 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1790 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1791 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1795 FOR_EACH_BB_REVERSE (bb)
1799 start[INSN_UID (BB_HEAD (bb))] = bb;
1800 end[INSN_UID (BB_END (bb))] = bb;
1801 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1803 enum bb_state state = IN_MULTIPLE_BB;
1805 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1807 in_bb_p[INSN_UID (x)] = state;
1809 if (x == BB_END (bb))
1814 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1818 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1820 fprintf (outf, ";; Start of basic block %d, registers live:",
1822 dump_regset (bb->global_live_at_start, outf);
1826 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1827 && !NOTE_P (tmp_rtx)
1828 && !BARRIER_P (tmp_rtx))
1829 fprintf (outf, ";; Insn is not within a basic block\n");
1830 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1831 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1833 did_output = print_rtl_single (outf, tmp_rtx);
1835 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1837 fprintf (outf, ";; End of basic block %d, registers live:\n",
1839 dump_regset (bb->global_live_at_end, outf);
1852 if (current_function_epilogue_delay_list != 0)
1854 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1855 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1856 tmp_rtx = XEXP (tmp_rtx, 1))
1857 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1862 update_br_prob_note (basic_block bb)
1865 if (!JUMP_P (BB_END (bb)))
1867 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1868 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1870 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1873 /* Verify the CFG and RTL consistency common for both underlying RTL and
1876 Currently it does following checks:
1878 - test head/end pointers
1879 - overlapping of basic blocks
1880 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1881 - tails of basic blocks (ensure that boundary is necessary)
1882 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1883 and NOTE_INSN_BASIC_BLOCK
1884 - verify that no fall_thru edge crosses hot/cold partition boundaries
1886 In future it can be extended check a lot of other stuff as well
1887 (reachability of basic blocks, life information, etc. etc.). */
1890 rtl_verify_flow_info_1 (void)
1892 const int max_uid = get_max_uid ();
1893 rtx last_head = get_last_insn ();
1894 basic_block *bb_info;
1899 bb_info = xcalloc (max_uid, sizeof (basic_block));
1901 FOR_EACH_BB_REVERSE (bb)
1903 rtx head = BB_HEAD (bb);
1904 rtx end = BB_END (bb);
1906 /* Verify the end of the basic block is in the INSN chain. */
1907 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1913 error ("end insn %d for block %d not found in the insn stream",
1914 INSN_UID (end), bb->index);
1918 /* Work backwards from the end to the head of the basic block
1919 to verify the head is in the RTL chain. */
1920 for (; x != NULL_RTX; x = PREV_INSN (x))
1922 /* While walking over the insn chain, verify insns appear
1923 in only one basic block and initialize the BB_INFO array
1924 used by other passes. */
1925 if (bb_info[INSN_UID (x)] != NULL)
1927 error ("insn %d is in multiple basic blocks (%d and %d)",
1928 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1932 bb_info[INSN_UID (x)] = bb;
1939 error ("head insn %d for block %d not found in the insn stream",
1940 INSN_UID (head), bb->index);
1947 /* Now check the basic blocks (boundaries etc.) */
1948 FOR_EACH_BB_REVERSE (bb)
1950 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1951 edge e, fallthru = NULL;
1955 if (JUMP_P (BB_END (bb))
1956 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1957 && EDGE_COUNT (bb->succs) >= 2
1958 && any_condjump_p (BB_END (bb)))
1960 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1961 && profile_status != PROFILE_ABSENT)
1963 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1964 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1968 FOR_EACH_EDGE (e, ei, bb->succs)
1970 if (e->flags & EDGE_FALLTHRU)
1972 n_fallthru++, fallthru = e;
1973 if ((e->flags & EDGE_CROSSING)
1974 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1975 && e->src != ENTRY_BLOCK_PTR
1976 && e->dest != EXIT_BLOCK_PTR))
1978 error ("Fallthru edge crosses section boundary (bb %i)",
1984 if ((e->flags & ~(EDGE_DFS_BACK
1986 | EDGE_IRREDUCIBLE_LOOP
1988 | EDGE_CROSSING)) == 0)
1991 if (e->flags & EDGE_ABNORMAL_CALL)
1994 if (e->flags & EDGE_EH)
1996 else if (e->flags & EDGE_ABNORMAL)
2000 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2001 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2003 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2007 && (!JUMP_P (BB_END (bb))
2008 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2009 || any_condjump_p (BB_END (bb))))))
2011 error ("Too many outgoing branch edges from bb %i", bb->index);
2014 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2016 error ("Fallthru edge after unconditional jump %i", bb->index);
2019 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2021 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2024 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2025 && JUMP_LABEL (BB_END (bb)) == BB_HEAD (fallthru->dest))
2027 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2030 if (n_call && !CALL_P (BB_END (bb)))
2032 error ("Call edges for non-call insn in bb %i", bb->index);
2036 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2037 && (!JUMP_P (BB_END (bb))
2038 || any_condjump_p (BB_END (bb))
2039 || any_uncondjump_p (BB_END (bb))))
2041 error ("Abnormal edges for no purpose in bb %i", bb->index);
2045 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2046 /* We may have a barrier inside a basic block before dead code
2047 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2048 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2051 if (! BLOCK_FOR_INSN (x))
2053 ("insn %d inside basic block %d but block_for_insn is NULL",
2054 INSN_UID (x), bb->index);
2057 ("insn %d inside basic block %d but block_for_insn is %i",
2058 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2063 /* OK pointers are correct. Now check the header of basic
2064 block. It ought to contain optional CODE_LABEL followed
2065 by NOTE_BASIC_BLOCK. */
2069 if (BB_END (bb) == x)
2071 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2079 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2081 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2086 if (BB_END (bb) == x)
2087 /* Do checks for empty blocks here. */
2090 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2092 if (NOTE_INSN_BASIC_BLOCK_P (x))
2094 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2095 INSN_UID (x), bb->index);
2099 if (x == BB_END (bb))
2102 if (control_flow_insn_p (x))
2104 error ("in basic block %d:", bb->index);
2105 fatal_insn ("flow control insn inside a basic block", x);
2115 /* Verify the CFG and RTL consistency common for both underlying RTL and
2118 Currently it does following checks:
2119 - all checks of rtl_verify_flow_info_1
2120 - check that all insns are in the basic blocks
2121 (except the switch handling code, barriers and notes)
2122 - check that all returns are followed by barriers
2123 - check that all fallthru edge points to the adjacent blocks. */
2125 rtl_verify_flow_info (void)
2128 int err = rtl_verify_flow_info_1 ();
2131 const rtx rtx_first = get_insns ();
2132 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2134 FOR_EACH_BB_REVERSE (bb)
2139 FOR_EACH_EDGE (e, ei, bb->succs)
2140 if (e->flags & EDGE_FALLTHRU)
2146 /* Ensure existence of barrier in BB with no fallthru edges. */
2147 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2148 insn = NEXT_INSN (insn))
2151 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2153 error ("missing barrier after block %i", bb->index);
2158 else if (e->src != ENTRY_BLOCK_PTR
2159 && e->dest != EXIT_BLOCK_PTR)
2163 if (e->src->next_bb != e->dest)
2166 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2167 e->src->index, e->dest->index);
2171 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2172 insn = NEXT_INSN (insn))
2173 if (BARRIER_P (insn) || INSN_P (insn))
2175 error ("verify_flow_info: Incorrect fallthru %i->%i",
2176 e->src->index, e->dest->index);
2177 fatal_insn ("wrong insn in the fallthru edge", insn);
2184 last_bb_seen = ENTRY_BLOCK_PTR;
2186 for (x = rtx_first; x; x = NEXT_INSN (x))
2188 if (NOTE_INSN_BASIC_BLOCK_P (x))
2190 bb = NOTE_BASIC_BLOCK (x);
2193 if (bb != last_bb_seen->next_bb)
2194 internal_error ("basic blocks not laid down consecutively");
2196 curr_bb = last_bb_seen = bb;
2201 switch (GET_CODE (x))
2208 /* An addr_vec is placed outside any basic block. */
2210 && JUMP_P (NEXT_INSN (x))
2211 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2212 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2215 /* But in any case, non-deletable labels can appear anywhere. */
2219 fatal_insn ("insn outside basic block", x);
2224 && returnjump_p (x) && ! condjump_p (x)
2225 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2226 fatal_insn ("return not followed by barrier", x);
2227 if (curr_bb && x == BB_END (curr_bb))
2231 if (num_bb_notes != n_basic_blocks)
2233 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2234 num_bb_notes, n_basic_blocks);
2239 /* Assume that the preceding pass has possibly eliminated jump instructions
2240 or converted the unconditional jumps. Eliminate the edges from CFG.
2241 Return true if any edges are eliminated. */
2244 purge_dead_edges (basic_block bb)
2247 rtx insn = BB_END (bb), note;
2248 bool purged = false;
2252 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2253 if (NONJUMP_INSN_P (insn)
2254 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2258 if (! may_trap_p (PATTERN (insn))
2259 || ((eqnote = find_reg_equal_equiv_note (insn))
2260 && ! may_trap_p (XEXP (eqnote, 0))))
2261 remove_note (insn, note);
2264 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2265 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2267 if (e->flags & EDGE_EH)
2269 if (can_throw_internal (BB_END (bb)))
2275 else if (e->flags & EDGE_ABNORMAL_CALL)
2277 if (CALL_P (BB_END (bb))
2278 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2279 || INTVAL (XEXP (note, 0)) >= 0))
2292 bb->flags |= BB_DIRTY;
2302 /* We do care only about conditional jumps and simplejumps. */
2303 if (!any_condjump_p (insn)
2304 && !returnjump_p (insn)
2305 && !simplejump_p (insn))
2308 /* Branch probability/prediction notes are defined only for
2309 condjumps. We've possibly turned condjump into simplejump. */
2310 if (simplejump_p (insn))
2312 note = find_reg_note (insn, REG_BR_PROB, NULL);
2314 remove_note (insn, note);
2315 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2316 remove_note (insn, note);
2319 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2321 /* Avoid abnormal flags to leak from computed jumps turned
2322 into simplejumps. */
2324 e->flags &= ~EDGE_ABNORMAL;
2326 /* See if this edge is one we should keep. */
2327 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2328 /* A conditional jump can fall through into the next
2329 block, so we should keep the edge. */
2334 else if (e->dest != EXIT_BLOCK_PTR
2335 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2336 /* 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. */
2349 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2350 /* Keep the edges that correspond to exceptions thrown by
2351 this instruction and rematerialize the EDGE_ABNORMAL
2352 flag we just cleared above. */
2354 e->flags |= EDGE_ABNORMAL;
2359 /* We do not need this edge. */
2360 bb->flags |= BB_DIRTY;
2365 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2369 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2374 /* Redistribute probabilities. */
2375 if (single_succ_p (bb))
2377 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2378 single_succ_edge (bb)->count = bb->count;
2382 note = find_reg_note (insn, REG_BR_PROB, NULL);
2386 b = BRANCH_EDGE (bb);
2387 f = FALLTHRU_EDGE (bb);
2388 b->probability = INTVAL (XEXP (note, 0));
2389 f->probability = REG_BR_PROB_BASE - b->probability;
2390 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2391 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2396 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2398 /* First, there should not be any EH or ABCALL edges resulting
2399 from non-local gotos and the like. If there were, we shouldn't
2400 have created the sibcall in the first place. Second, there
2401 should of course never have been a fallthru edge. */
2402 gcc_assert (single_succ_p (bb));
2403 gcc_assert (single_succ_edge (bb)->flags
2404 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2409 /* If we don't see a jump insn, we don't know exactly why the block would
2410 have been broken at this point. Look for a simple, non-fallthru edge,
2411 as these are only created by conditional branches. If we find such an
2412 edge we know that there used to be a jump here and can then safely
2413 remove all non-fallthru edges. */
2415 FOR_EACH_EDGE (e, ei, bb->succs)
2416 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2425 /* Remove all but the fake and fallthru edges. The fake edge may be
2426 the only successor for this block in the case of noreturn
2428 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2430 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2432 bb->flags |= BB_DIRTY;
2440 gcc_assert (single_succ_p (bb));
2442 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2443 single_succ_edge (bb)->count = bb->count;
2446 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2451 /* Search all basic blocks for potentially dead edges and purge them. Return
2452 true if some edge has been eliminated. */
2455 purge_all_dead_edges (void)
2462 bool purged_here = purge_dead_edges (bb);
2464 purged |= purged_here;
2470 /* Same as split_block but update cfg_layout structures. */
2473 cfg_layout_split_block (basic_block bb, void *insnp)
2476 basic_block new_bb = rtl_split_block (bb, insn);
2478 new_bb->rbi->footer = bb->rbi->footer;
2479 bb->rbi->footer = NULL;
2485 /* Redirect Edge to DEST. */
2487 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2489 basic_block src = e->src;
2492 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2495 if (e->dest == dest)
2498 if (e->src != ENTRY_BLOCK_PTR
2499 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2501 src->flags |= BB_DIRTY;
2505 if (e->src == ENTRY_BLOCK_PTR
2506 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2509 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2510 e->src->index, dest->index);
2512 e->src->flags |= BB_DIRTY;
2513 redirect_edge_succ (e, dest);
2517 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2518 in the case the basic block appears to be in sequence. Avoid this
2521 if (e->flags & EDGE_FALLTHRU)
2523 /* Redirect any branch edges unified with the fallthru one. */
2524 if (JUMP_P (BB_END (src))
2525 && label_is_jump_target_p (BB_HEAD (e->dest),
2531 fprintf (dump_file, "Fallthru edge unified with branch "
2532 "%i->%i redirected to %i\n",
2533 e->src->index, e->dest->index, dest->index);
2534 e->flags &= ~EDGE_FALLTHRU;
2535 redirected = redirect_branch_edge (e, dest);
2536 gcc_assert (redirected);
2537 e->flags |= EDGE_FALLTHRU;
2538 e->src->flags |= BB_DIRTY;
2541 /* In case we are redirecting fallthru edge to the branch edge
2542 of conditional jump, remove it. */
2543 if (EDGE_COUNT (src->succs) == 2)
2545 /* Find the edge that is different from E. */
2546 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2549 && any_condjump_p (BB_END (src))
2550 && onlyjump_p (BB_END (src)))
2551 delete_insn (BB_END (src));
2553 ret = redirect_edge_succ_nodup (e, dest);
2555 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2556 e->src->index, e->dest->index, dest->index);
2559 ret = redirect_branch_edge (e, dest);
2561 /* We don't want simplejumps in the insn stream during cfglayout. */
2562 gcc_assert (!simplejump_p (BB_END (src)));
2564 src->flags |= BB_DIRTY;
2568 /* Simple wrapper as we always can redirect fallthru edges. */
2570 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2572 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2574 gcc_assert (redirected);
2578 /* Same as delete_basic_block but update cfg_layout structures. */
2581 cfg_layout_delete_block (basic_block bb)
2583 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2585 if (bb->rbi->header)
2587 next = BB_HEAD (bb);
2589 NEXT_INSN (prev) = bb->rbi->header;
2591 set_first_insn (bb->rbi->header);
2592 PREV_INSN (bb->rbi->header) = prev;
2593 insn = bb->rbi->header;
2594 while (NEXT_INSN (insn))
2595 insn = NEXT_INSN (insn);
2596 NEXT_INSN (insn) = next;
2597 PREV_INSN (next) = insn;
2599 next = NEXT_INSN (BB_END (bb));
2600 if (bb->rbi->footer)
2602 insn = bb->rbi->footer;
2605 if (BARRIER_P (insn))
2607 if (PREV_INSN (insn))
2608 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2610 bb->rbi->footer = NEXT_INSN (insn);
2611 if (NEXT_INSN (insn))
2612 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2616 insn = NEXT_INSN (insn);
2618 if (bb->rbi->footer)
2621 NEXT_INSN (insn) = bb->rbi->footer;
2622 PREV_INSN (bb->rbi->footer) = insn;
2623 while (NEXT_INSN (insn))
2624 insn = NEXT_INSN (insn);
2625 NEXT_INSN (insn) = next;
2627 PREV_INSN (next) = insn;
2629 set_last_insn (insn);
2632 if (bb->next_bb != EXIT_BLOCK_PTR)
2633 to = &bb->next_bb->rbi->header;
2635 to = &cfg_layout_function_footer;
2639 rtl_delete_block (bb);
2642 prev = NEXT_INSN (prev);
2644 prev = get_insns ();
2646 next = PREV_INSN (next);
2648 next = get_last_insn ();
2650 if (next && NEXT_INSN (next) != prev)
2652 remaints = unlink_insn_chain (prev, next);
2654 while (NEXT_INSN (insn))
2655 insn = NEXT_INSN (insn);
2656 NEXT_INSN (insn) = *to;
2658 PREV_INSN (*to) = insn;
2663 /* Return true when blocks A and B can be safely merged. */
2665 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2667 /* If we are partitioning hot/cold basic blocks, we don't want to
2668 mess up unconditional or indirect jumps that cross between hot
2671 Basic block partitioning may result in some jumps that appear to
2672 be optimizable (or blocks that appear to be mergeable), but which really
2673 must be left untouched (they are required to make it safely across
2674 partition boundaries). See the comments at the top of
2675 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2677 if (BB_PARTITION (a) != BB_PARTITION (b))
2680 /* There must be exactly one edge in between the blocks. */
2681 return (single_succ_p (a)
2682 && single_succ (a) == b
2683 && single_pred_p (b) == 1
2685 /* Must be simple edge. */
2686 && !(single_succ_edge (a)->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. The blocks must be mergeable. */
2698 cfg_layout_merge_blocks (basic_block a, basic_block b)
2700 #ifdef ENABLE_CHECKING
2701 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2704 /* If there was a CODE_LABEL beginning B, delete it. */
2705 if (LABEL_P (BB_HEAD (b)))
2706 delete_insn (BB_HEAD (b));
2708 /* We should have fallthru edge in a, or we can do dummy redirection to get
2710 if (JUMP_P (BB_END (a)))
2711 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2712 gcc_assert (!JUMP_P (BB_END (a)));
2714 /* Possible line number notes should appear in between. */
2717 rtx first = BB_END (a), last;
2719 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2720 delete_insn_chain (NEXT_INSN (first), last);
2721 b->rbi->header = NULL;
2724 /* In the case basic blocks are not adjacent, move them around. */
2725 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2727 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2729 emit_insn_after_noloc (first, BB_END (a));
2730 /* Skip possible DELETED_LABEL insn. */
2731 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2732 first = NEXT_INSN (first);
2733 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2735 delete_insn (first);
2737 /* Otherwise just re-associate the instructions. */
2742 for (insn = BB_HEAD (b);
2743 insn != NEXT_INSN (BB_END (b));
2744 insn = NEXT_INSN (insn))
2745 set_block_for_insn (insn, a);
2747 /* Skip possible DELETED_LABEL insn. */
2748 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2749 insn = NEXT_INSN (insn);
2750 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2752 BB_END (a) = BB_END (b);
2756 /* Possible tablejumps and barriers should appear after the block. */
2759 if (!a->rbi->footer)
2760 a->rbi->footer = b->rbi->footer;
2763 rtx last = a->rbi->footer;
2765 while (NEXT_INSN (last))
2766 last = NEXT_INSN (last);
2767 NEXT_INSN (last) = b->rbi->footer;
2768 PREV_INSN (b->rbi->footer) = last;
2770 b->rbi->footer = NULL;
2774 fprintf (dump_file, "Merged blocks %d and %d.\n",
2775 a->index, b->index);
2781 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 = ALLOC_REG_SET (®_obstack);
2793 new_bb->global_live_at_end = ALLOC_REG_SET (®_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 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 && !CONST_OR_PURE_CALL_P (insn)))
2851 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2852 && MEM_VOLATILE_P (PATTERN (insn)))
2853 || (GET_CODE (PATTERN (insn)) == PARALLEL
2854 && asm_noperands (insn) != -1
2855 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2856 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2859 /* Add fake edges to the function exit for any non constant and non noreturn
2860 calls, volatile inline assembly in the bitmap of blocks specified by
2861 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2864 The goal is to expose cases in which entering a basic block does not imply
2865 that all subsequent instructions must be executed. */
2868 rtl_flow_call_edges_add (sbitmap blocks)
2871 int blocks_split = 0;
2872 int last_bb = last_basic_block;
2873 bool check_last_block = false;
2875 if (n_basic_blocks == 0)
2879 check_last_block = true;
2881 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2883 /* In the last basic block, before epilogue generation, there will be
2884 a fallthru edge to EXIT. Special care is required if the last insn
2885 of the last basic block is a call because make_edge folds duplicate
2886 edges, which would result in the fallthru edge also being marked
2887 fake, which would result in the fallthru edge being removed by
2888 remove_fake_edges, which would result in an invalid CFG.
2890 Moreover, we can't elide the outgoing fake edge, since the block
2891 profiler needs to take this into account in order to solve the minimal
2892 spanning tree in the case that the call doesn't return.
2894 Handle this by adding a dummy instruction in a new last basic block. */
2895 if (check_last_block)
2897 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2898 rtx insn = BB_END (bb);
2900 /* Back up past insns that must be kept in the same block as a call. */
2901 while (insn != BB_HEAD (bb)
2902 && keep_with_call_p (insn))
2903 insn = PREV_INSN (insn);
2905 if (need_fake_edge_p (insn))
2909 e = find_edge (bb, EXIT_BLOCK_PTR);
2912 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2913 commit_edge_insertions ();
2918 /* Now add fake edges to the function exit for any non constant
2919 calls since there is no way that we can determine if they will
2922 for (i = 0; i < last_bb; i++)
2924 basic_block bb = BASIC_BLOCK (i);
2931 if (blocks && !TEST_BIT (blocks, i))
2934 for (insn = BB_END (bb); ; insn = prev_insn)
2936 prev_insn = PREV_INSN (insn);
2937 if (need_fake_edge_p (insn))
2940 rtx split_at_insn = insn;
2942 /* Don't split the block between a call and an insn that should
2943 remain in the same block as the call. */
2945 while (split_at_insn != BB_END (bb)
2946 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2947 split_at_insn = NEXT_INSN (split_at_insn);
2949 /* The handling above of the final block before the epilogue
2950 should be enough to verify that there is no edge to the exit
2951 block in CFG already. Calling make_edge in such case would
2952 cause us to mark that edge as fake and remove it later. */
2954 #ifdef ENABLE_CHECKING
2955 if (split_at_insn == BB_END (bb))
2957 e = find_edge (bb, EXIT_BLOCK_PTR);
2958 gcc_assert (e == NULL);
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 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2986 the conditional branch target, SECOND_HEAD should be the fall-thru
2987 there is no need to handle this here the loop versioning code handles
2988 this. the reason for SECON_HEAD is that it is needed for condition
2989 in trees, and this should be of the same type since it is a hook. */
2991 rtl_lv_add_condition_to_bb (basic_block first_head ,
2992 basic_block second_head ATTRIBUTE_UNUSED,
2993 basic_block cond_bb, void *comp_rtx)
2995 rtx label, seq, jump;
2996 rtx op0 = XEXP ((rtx)comp_rtx, 0);
2997 rtx op1 = XEXP ((rtx)comp_rtx, 1);
2998 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
2999 enum machine_mode mode;
3002 label = block_label (first_head);
3003 mode = GET_MODE (op0);
3004 if (mode == VOIDmode)
3005 mode = GET_MODE (op1);
3008 op0 = force_operand (op0, NULL_RTX);
3009 op1 = force_operand (op1, NULL_RTX);
3010 do_compare_rtx_and_jump (op0, op1, comp, 0,
3011 mode, NULL_RTX, NULL_RTX, label);
3012 jump = get_last_insn ();
3013 JUMP_LABEL (jump) = label;
3014 LABEL_NUSES (label)++;
3018 /* Add the new cond , in the new head. */
3019 emit_insn_after(seq, BB_END(cond_bb));
3023 /* Given a block B with unconditional branch at its end, get the
3024 store the return the branch edge and the fall-thru edge in
3025 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
3027 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
3028 edge *fallthru_edge)
3030 edge e = EDGE_SUCC (b, 0);
3032 if (e->flags & EDGE_FALLTHRU)
3035 *branch_edge = EDGE_SUCC (b, 1);
3040 *fallthru_edge = EDGE_SUCC (b, 1);
3045 /* Implementation of CFG manipulation for linearized RTL. */
3046 struct cfg_hooks rtl_cfg_hooks = {
3048 rtl_verify_flow_info,
3050 rtl_create_basic_block,
3051 rtl_redirect_edge_and_branch,
3052 rtl_redirect_edge_and_branch_force,
3055 rtl_move_block_after,
3056 rtl_can_merge_blocks, /* can_merge_blocks_p */
3060 NULL, /* can_duplicate_block_p */
3061 NULL, /* duplicate_block */
3063 rtl_make_forwarder_block,
3064 rtl_tidy_fallthru_edge,
3065 rtl_block_ends_with_call_p,
3066 rtl_block_ends_with_condjump_p,
3067 rtl_flow_call_edges_add,
3068 NULL, /* execute_on_growing_pred */
3069 NULL, /* execute_on_shrinking_pred */
3070 NULL, /* duplicate loop for trees */
3071 NULL, /* lv_add_condition_to_bb */
3072 NULL, /* lv_adjust_loop_header_phi*/
3073 NULL, /* extract_cond_bb_edges */
3074 NULL /* flush_pending_stmts */
3077 /* Implementation of CFG manipulation for cfg layout RTL, where
3078 basic block connected via fallthru edges does not have to be adjacent.
3079 This representation will hopefully become the default one in future
3080 version of the compiler. */
3082 /* We do not want to declare these functions in a header file, since they
3083 should only be used through the cfghooks interface, and we do not want to
3084 move them here since it would require also moving quite a lot of related
3086 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3087 extern basic_block cfg_layout_duplicate_bb (basic_block);
3089 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3091 rtl_verify_flow_info_1,
3093 cfg_layout_create_basic_block,
3094 cfg_layout_redirect_edge_and_branch,
3095 cfg_layout_redirect_edge_and_branch_force,
3096 cfg_layout_delete_block,
3097 cfg_layout_split_block,
3098 rtl_move_block_after,
3099 cfg_layout_can_merge_blocks_p,
3100 cfg_layout_merge_blocks,
3103 cfg_layout_can_duplicate_bb_p,
3104 cfg_layout_duplicate_bb,
3105 cfg_layout_split_edge,
3106 rtl_make_forwarder_block,
3108 rtl_block_ends_with_call_p,
3109 rtl_block_ends_with_condjump_p,
3110 rtl_flow_call_edges_add,
3111 NULL, /* execute_on_growing_pred */
3112 NULL, /* execute_on_shrinking_pred */
3113 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3114 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3115 NULL, /* lv_adjust_loop_header_phi*/
3116 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3117 NULL /* flush_pending_stmts */