1 /* Basic block reordering routines for the GNU compiler.
2 Copyright (C) 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 2, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
27 #include "hard-reg-set.h"
29 #include "basic-block.h"
30 #include "insn-config.h"
33 #include "cfglayout.h"
37 #include "alloc-pool.h"
40 /* Holds the interesting trailing notes for the function. */
41 rtx cfg_layout_function_footer, cfg_layout_function_header;
43 static rtx skip_insns_after_block (basic_block);
44 static void record_effective_endpoints (void);
45 static rtx label_for_bb (basic_block);
46 static void fixup_reorder_chain (void);
48 static void set_block_levels (tree, int);
49 static void change_scope (rtx, tree, tree);
51 void verify_insn_chain (void);
52 static void fixup_fallthru_exit_predecessor (void);
53 static tree insn_scope (rtx);
54 static void update_unlikely_executed_notes (basic_block);
57 unlink_insn_chain (rtx first, rtx last)
59 rtx prevfirst = PREV_INSN (first);
60 rtx nextlast = NEXT_INSN (last);
62 PREV_INSN (first) = NULL;
63 NEXT_INSN (last) = NULL;
65 NEXT_INSN (prevfirst) = nextlast;
67 PREV_INSN (nextlast) = prevfirst;
69 set_last_insn (prevfirst);
71 set_first_insn (nextlast);
75 /* Skip over inter-block insns occurring after BB which are typically
76 associated with BB (e.g., barriers). If there are any such insns,
77 we return the last one. Otherwise, we return the end of BB. */
80 skip_insns_after_block (basic_block bb)
82 rtx insn, last_insn, next_head, prev;
85 if (bb->next_bb != EXIT_BLOCK_PTR)
86 next_head = BB_HEAD (bb->next_bb);
88 for (last_insn = insn = BB_END (bb); (insn = NEXT_INSN (insn)) != 0; )
90 if (insn == next_head)
93 switch (GET_CODE (insn))
100 switch (NOTE_LINE_NUMBER (insn))
102 case NOTE_INSN_LOOP_END:
103 case NOTE_INSN_BLOCK_END:
106 case NOTE_INSN_DELETED:
107 case NOTE_INSN_DELETED_LABEL:
118 && JUMP_P (NEXT_INSN (insn))
119 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
120 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
122 insn = NEXT_INSN (insn);
135 /* It is possible to hit contradictory sequence. For instance:
141 Where barrier belongs to jump_insn, but the note does not. This can be
142 created by removing the basic block originally following
143 NOTE_INSN_LOOP_BEG. In such case reorder the notes. */
145 for (insn = last_insn; insn != BB_END (bb); insn = prev)
147 prev = PREV_INSN (insn);
149 switch (NOTE_LINE_NUMBER (insn))
151 case NOTE_INSN_LOOP_END:
152 case NOTE_INSN_BLOCK_END:
153 case NOTE_INSN_DELETED:
154 case NOTE_INSN_DELETED_LABEL:
157 reorder_insns (insn, insn, last_insn);
164 /* Locate or create a label for a given basic block. */
167 label_for_bb (basic_block bb)
169 rtx label = BB_HEAD (bb);
171 if (!LABEL_P (label))
174 fprintf (dump_file, "Emitting label for block %d\n", bb->index);
176 label = block_label (bb);
182 /* Locate the effective beginning and end of the insn chain for each
183 block, as defined by skip_insns_after_block above. */
186 record_effective_endpoints (void)
192 for (insn = get_insns ();
195 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
196 insn = NEXT_INSN (insn))
198 /* No basic blocks at all? */
201 if (PREV_INSN (insn))
202 cfg_layout_function_header =
203 unlink_insn_chain (get_insns (), PREV_INSN (insn));
205 cfg_layout_function_header = NULL_RTX;
207 next_insn = get_insns ();
212 if (PREV_INSN (BB_HEAD (bb)) && next_insn != BB_HEAD (bb))
213 bb->rbi->header = unlink_insn_chain (next_insn,
214 PREV_INSN (BB_HEAD (bb)));
215 end = skip_insns_after_block (bb);
216 if (NEXT_INSN (BB_END (bb)) && BB_END (bb) != end)
217 bb->rbi->footer = unlink_insn_chain (NEXT_INSN (BB_END (bb)), end);
218 next_insn = NEXT_INSN (BB_END (bb));
221 cfg_layout_function_footer = next_insn;
222 if (cfg_layout_function_footer)
223 cfg_layout_function_footer = unlink_insn_chain (cfg_layout_function_footer, get_last_insn ());
226 /* Data structures representing mapping of INSN_LOCATOR into scope blocks, line
227 numbers and files. In order to be GGC friendly we need to use separate
228 varrays. This also slightly improve the memory locality in binary search.
229 The _locs array contains locators where the given property change. The
230 block_locators_blocks contains the scope block that is used for all insn
231 locator greater than corresponding block_locators_locs value and smaller
232 than the following one. Similarly for the other properties. */
233 static GTY(()) varray_type block_locators_locs;
234 static GTY(()) varray_type block_locators_blocks;
235 static GTY(()) varray_type line_locators_locs;
236 static GTY(()) varray_type line_locators_lines;
237 static GTY(()) varray_type file_locators_locs;
238 static GTY(()) varray_type file_locators_files;
239 int prologue_locator;
240 int epilogue_locator;
242 /* During the RTL expansion the lexical blocks and line numbers are
243 represented via INSN_NOTEs. Replace them by representation using
247 insn_locators_initialize (void)
250 tree last_block = NULL;
253 int line_number = 0, last_line_number = 0;
254 const char *file_name = NULL, *last_file_name = NULL;
256 prologue_locator = epilogue_locator = 0;
258 VARRAY_INT_INIT (block_locators_locs, 32, "block_locators_locs");
259 VARRAY_TREE_INIT (block_locators_blocks, 32, "block_locators_blocks");
260 VARRAY_INT_INIT (line_locators_locs, 32, "line_locators_locs");
261 VARRAY_INT_INIT (line_locators_lines, 32, "line_locators_lines");
262 VARRAY_INT_INIT (file_locators_locs, 32, "file_locators_locs");
263 VARRAY_CHAR_PTR_INIT (file_locators_files, 32, "file_locators_files");
265 for (insn = get_insns (); insn; insn = next)
269 next = NEXT_INSN (insn);
273 gcc_assert (NOTE_LINE_NUMBER (insn) != NOTE_INSN_BLOCK_BEG
274 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BLOCK_END);
275 if (NOTE_LINE_NUMBER (insn) > 0)
277 expanded_location xloc;
278 NOTE_EXPANDED_LOCATION (xloc, insn);
279 line_number = xloc.line;
280 file_name = xloc.file;
284 active = (active_insn_p (insn)
285 && GET_CODE (PATTERN (insn)) != ADDR_VEC
286 && GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC);
288 check_block_change (insn, &block);
292 || (!prologue_locator && file_name))
294 if (last_block != block)
297 VARRAY_PUSH_INT (block_locators_locs, loc);
298 VARRAY_PUSH_TREE (block_locators_blocks, block);
301 if (last_line_number != line_number)
304 VARRAY_PUSH_INT (line_locators_locs, loc);
305 VARRAY_PUSH_INT (line_locators_lines, line_number);
306 last_line_number = line_number;
308 if (last_file_name != file_name)
311 VARRAY_PUSH_INT (file_locators_locs, loc);
312 VARRAY_PUSH_CHAR_PTR (file_locators_files, (char *) file_name);
313 last_file_name = file_name;
315 if (!prologue_locator && file_name)
316 prologue_locator = loc;
318 epilogue_locator = loc;
320 INSN_LOCATOR (insn) = loc;
324 /* Tag the blocks with a depth number so that change_scope can find
325 the common parent easily. */
326 set_block_levels (DECL_INITIAL (cfun->decl), 0);
328 free_block_changes ();
331 /* For each lexical block, set BLOCK_NUMBER to the depth at which it is
332 found in the block tree. */
335 set_block_levels (tree block, int level)
339 BLOCK_NUMBER (block) = level;
340 set_block_levels (BLOCK_SUBBLOCKS (block), level + 1);
341 block = BLOCK_CHAIN (block);
345 /* Return sope resulting from combination of S1 and S2. */
347 choose_inner_scope (tree s1, tree s2)
353 if (BLOCK_NUMBER (s1) > BLOCK_NUMBER (s2))
358 /* Emit lexical block notes needed to change scope from S1 to S2. */
361 change_scope (rtx orig_insn, tree s1, tree s2)
363 rtx insn = orig_insn;
364 tree com = NULL_TREE;
365 tree ts1 = s1, ts2 = s2;
370 gcc_assert (ts1 && ts2);
371 if (BLOCK_NUMBER (ts1) > BLOCK_NUMBER (ts2))
372 ts1 = BLOCK_SUPERCONTEXT (ts1);
373 else if (BLOCK_NUMBER (ts1) < BLOCK_NUMBER (ts2))
374 ts2 = BLOCK_SUPERCONTEXT (ts2);
377 ts1 = BLOCK_SUPERCONTEXT (ts1);
378 ts2 = BLOCK_SUPERCONTEXT (ts2);
387 rtx note = emit_note_before (NOTE_INSN_BLOCK_END, insn);
388 NOTE_BLOCK (note) = s;
389 s = BLOCK_SUPERCONTEXT (s);
396 insn = emit_note_before (NOTE_INSN_BLOCK_BEG, insn);
397 NOTE_BLOCK (insn) = s;
398 s = BLOCK_SUPERCONTEXT (s);
402 /* Return lexical scope block insn belong to. */
404 insn_scope (rtx insn)
406 int max = VARRAY_ACTIVE_SIZE (block_locators_locs);
408 int loc = INSN_LOCATOR (insn);
410 /* When block_locators_locs was initialized, the pro- and epilogue
411 insns didn't exist yet and can therefore not be found this way.
412 But we know that they belong to the outer most block of the
414 Without this test, the prologue would be put inside the block of
415 the first valid instruction in the function and when that first
416 insn is part of an inlined function then the low_pc of that
417 inlined function is messed up. Likewise for the epilogue and
418 the last valid instruction. */
419 if (loc == prologue_locator || loc == epilogue_locator)
420 return DECL_INITIAL (cfun->decl);
426 int pos = (min + max) / 2;
427 int tmp = VARRAY_INT (block_locators_locs, pos);
429 if (tmp <= loc && min != pos)
431 else if (tmp > loc && max != pos)
439 return VARRAY_TREE (block_locators_blocks, min);
442 /* Return line number of the statement specified by the locator. */
444 locator_line (int loc)
446 int max = VARRAY_ACTIVE_SIZE (line_locators_locs);
453 int pos = (min + max) / 2;
454 int tmp = VARRAY_INT (line_locators_locs, pos);
456 if (tmp <= loc && min != pos)
458 else if (tmp > loc && max != pos)
466 return VARRAY_INT (line_locators_lines, min);
469 /* Return line number of the statement that produced this insn. */
473 return locator_line (INSN_LOCATOR (insn));
476 /* Return source file of the statement specified by LOC. */
478 locator_file (int loc)
480 int max = VARRAY_ACTIVE_SIZE (file_locators_locs);
487 int pos = (min + max) / 2;
488 int tmp = VARRAY_INT (file_locators_locs, pos);
490 if (tmp <= loc && min != pos)
492 else if (tmp > loc && max != pos)
500 return VARRAY_CHAR_PTR (file_locators_files, min);
503 /* Return source file of the statement that produced this insn. */
507 return locator_file (INSN_LOCATOR (insn));
510 /* Rebuild all the NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes based
511 on the scope tree and the newly reordered instructions. */
514 reemit_insn_block_notes (void)
516 tree cur_block = DECL_INITIAL (cfun->decl);
520 if (!active_insn_p (insn))
521 insn = next_active_insn (insn);
522 for (; insn; insn = next_active_insn (insn))
526 this_block = insn_scope (insn);
527 /* For sequences compute scope resulting from merging all scopes
528 of instructions nested inside. */
529 if (GET_CODE (PATTERN (insn)) == SEQUENCE)
532 rtx body = PATTERN (insn);
535 for (i = 0; i < XVECLEN (body, 0); i++)
536 this_block = choose_inner_scope (this_block,
537 insn_scope (XVECEXP (body, 0, i)));
542 if (this_block != cur_block)
544 change_scope (insn, cur_block, this_block);
545 cur_block = this_block;
549 /* change_scope emits before the insn, not after. */
550 note = emit_note (NOTE_INSN_DELETED);
551 change_scope (note, cur_block, DECL_INITIAL (cfun->decl));
557 /* Given a reorder chain, rearrange the code to match. */
560 fixup_reorder_chain (void)
562 basic_block bb, prev_bb;
566 if (cfg_layout_function_header)
568 set_first_insn (cfg_layout_function_header);
569 insn = cfg_layout_function_header;
570 while (NEXT_INSN (insn))
571 insn = NEXT_INSN (insn);
574 /* First do the bulk reordering -- rechain the blocks without regard to
575 the needed changes to jumps and labels. */
577 for (bb = ENTRY_BLOCK_PTR->next_bb, index = 0;
579 bb = bb->rbi->next, index++)
584 NEXT_INSN (insn) = bb->rbi->header;
586 set_first_insn (bb->rbi->header);
587 PREV_INSN (bb->rbi->header) = insn;
588 insn = bb->rbi->header;
589 while (NEXT_INSN (insn))
590 insn = NEXT_INSN (insn);
593 NEXT_INSN (insn) = BB_HEAD (bb);
595 set_first_insn (BB_HEAD (bb));
596 PREV_INSN (BB_HEAD (bb)) = insn;
600 NEXT_INSN (insn) = bb->rbi->footer;
601 PREV_INSN (bb->rbi->footer) = insn;
602 while (NEXT_INSN (insn))
603 insn = NEXT_INSN (insn);
607 gcc_assert (index == n_basic_blocks);
609 NEXT_INSN (insn) = cfg_layout_function_footer;
610 if (cfg_layout_function_footer)
611 PREV_INSN (cfg_layout_function_footer) = insn;
613 while (NEXT_INSN (insn))
614 insn = NEXT_INSN (insn);
616 set_last_insn (insn);
617 #ifdef ENABLE_CHECKING
618 verify_insn_chain ();
620 delete_dead_jumptables ();
622 /* Now add jumps and labels as needed to match the blocks new
625 for (bb = ENTRY_BLOCK_PTR->next_bb; bb ; bb = bb->rbi->next)
627 edge e_fall, e_taken, e;
633 if (EDGE_COUNT (bb->succs) == 0)
636 /* Find the old fallthru edge, and another non-EH edge for
638 e_taken = e_fall = NULL;
640 FOR_EACH_EDGE (e, ei, bb->succs)
641 if (e->flags & EDGE_FALLTHRU)
643 else if (! (e->flags & EDGE_EH))
646 bb_end_insn = BB_END (bb);
647 if (JUMP_P (bb_end_insn))
649 if (any_condjump_p (bb_end_insn))
651 /* If the old fallthru is still next, nothing to do. */
652 if (bb->rbi->next == e_fall->dest
653 || e_fall->dest == EXIT_BLOCK_PTR)
656 /* The degenerated case of conditional jump jumping to the next
657 instruction can happen on target having jumps with side
660 Create temporarily the duplicated edge representing branch.
661 It will get unidentified by force_nonfallthru_and_redirect
662 that would otherwise get confused by fallthru edge not pointing
663 to the next basic block. */
670 e_fake = unchecked_make_edge (bb, e_fall->dest, 0);
672 redirected = redirect_jump (BB_END (bb),
673 block_label (bb), 0);
674 gcc_assert (redirected);
676 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
679 int prob = INTVAL (XEXP (note, 0));
681 e_fake->probability = prob;
682 e_fake->count = e_fall->count * prob / REG_BR_PROB_BASE;
683 e_fall->probability -= e_fall->probability;
684 e_fall->count -= e_fake->count;
685 if (e_fall->probability < 0)
686 e_fall->probability = 0;
687 if (e_fall->count < 0)
691 /* There is one special case: if *neither* block is next,
692 such as happens at the very end of a function, then we'll
693 need to add a new unconditional jump. Choose the taken
694 edge based on known or assumed probability. */
695 else if (bb->rbi->next != e_taken->dest)
697 rtx note = find_reg_note (bb_end_insn, REG_BR_PROB, 0);
700 && INTVAL (XEXP (note, 0)) < REG_BR_PROB_BASE / 2
701 && invert_jump (bb_end_insn,
702 (e_fall->dest == EXIT_BLOCK_PTR
704 : label_for_bb (e_fall->dest)), 0))
706 e_fall->flags &= ~EDGE_FALLTHRU;
707 #ifdef ENABLE_CHECKING
708 gcc_assert (could_fall_through
709 (e_taken->src, e_taken->dest));
711 e_taken->flags |= EDGE_FALLTHRU;
712 update_br_prob_note (bb);
713 e = e_fall, e_fall = e_taken, e_taken = e;
717 /* If the "jumping" edge is a crossing edge, and the fall
718 through edge is non-crossing, leave things as they are. */
719 else if ((e_taken->flags & EDGE_CROSSING)
720 && !(e_fall->flags & EDGE_CROSSING))
723 /* Otherwise we can try to invert the jump. This will
724 basically never fail, however, keep up the pretense. */
725 else if (invert_jump (bb_end_insn,
726 (e_fall->dest == EXIT_BLOCK_PTR
728 : label_for_bb (e_fall->dest)), 0))
730 e_fall->flags &= ~EDGE_FALLTHRU;
731 #ifdef ENABLE_CHECKING
732 gcc_assert (could_fall_through
733 (e_taken->src, e_taken->dest));
735 e_taken->flags |= EDGE_FALLTHRU;
736 update_br_prob_note (bb);
742 #ifndef CASE_DROPS_THROUGH
743 /* Otherwise we have some return, switch or computed
744 jump. In the 99% case, there should not have been a
746 gcc_assert (returnjump_p (bb_end_insn) || !e_fall);
749 if (returnjump_p (bb_end_insn) || !e_fall)
751 /* Except for VAX. Since we didn't have predication for the
752 tablejump, the fallthru block should not have moved. */
753 if (bb->rbi->next == e_fall->dest)
755 bb_end_insn = skip_insns_after_block (bb);
761 /* No fallthru implies a noreturn function with EH edges, or
762 something similarly bizarre. In any case, we don't need to
767 /* If the fallthru block is still next, nothing to do. */
768 if (bb->rbi->next == e_fall->dest)
771 /* A fallthru to exit block. */
772 if (e_fall->dest == EXIT_BLOCK_PTR)
776 /* We got here if we need to add a new jump insn. */
777 nb = force_nonfallthru (e_fall);
780 initialize_bb_rbi (nb);
781 nb->rbi->visited = 1;
782 nb->rbi->next = bb->rbi->next;
784 /* Don't process this new block. */
788 /* Make sure new bb is tagged for correct section (same as
789 fall-thru source, since you cannot fall-throu across
790 section boundaries). */
791 BB_COPY_PARTITION (e_fall->src, EDGE_PRED (bb, 0)->src);
792 if (flag_reorder_blocks_and_partition
793 && targetm.have_named_sections)
795 if (BB_PARTITION (EDGE_PRED (bb, 0)->src) == BB_COLD_PARTITION)
798 rtx note = BB_HEAD (e_fall->src);
800 while (!INSN_P (note)
801 && note != BB_END (e_fall->src))
802 note = NEXT_INSN (note);
804 new_note = emit_note_before
805 (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
807 NOTE_BASIC_BLOCK (new_note) = bb;
809 if (JUMP_P (BB_END (bb))
810 && !any_condjump_p (BB_END (bb))
811 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
812 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
813 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
818 /* Put basic_block_info in the new order. */
822 fprintf (dump_file, "Reordered sequence:\n");
823 for (bb = ENTRY_BLOCK_PTR->next_bb, index = 0;
825 bb = bb->rbi->next, index++)
827 fprintf (dump_file, " %i ", index);
828 if (bb->rbi->original)
829 fprintf (dump_file, "duplicate of %i ",
830 bb->rbi->original->index);
831 else if (forwarder_block_p (bb)
832 && !LABEL_P (BB_HEAD (bb)))
833 fprintf (dump_file, "compensation ");
835 fprintf (dump_file, "bb %i ", bb->index);
836 fprintf (dump_file, " [%i]\n", bb->frequency);
840 prev_bb = ENTRY_BLOCK_PTR;
841 bb = ENTRY_BLOCK_PTR->next_bb;
844 for (; bb; prev_bb = bb, bb = bb->rbi->next, index ++)
847 BASIC_BLOCK (index) = bb;
849 update_unlikely_executed_notes (bb);
851 bb->prev_bb = prev_bb;
852 prev_bb->next_bb = bb;
854 prev_bb->next_bb = EXIT_BLOCK_PTR;
855 EXIT_BLOCK_PTR->prev_bb = prev_bb;
857 /* Annoying special case - jump around dead jumptables left in the code. */
863 FOR_EACH_EDGE (e, ei, bb->succs)
864 if (e->flags & EDGE_FALLTHRU)
867 if (e && !can_fallthru (e->src, e->dest))
868 force_nonfallthru (e);
872 /* Update the basic block number information in any
873 NOTE_INSN_UNLIKELY_EXECUTED_CODE notes within the basic block. */
876 update_unlikely_executed_notes (basic_block bb)
880 for (cur_insn = BB_HEAD (bb); cur_insn != BB_END (bb);
881 cur_insn = NEXT_INSN (cur_insn))
882 if (NOTE_P (cur_insn)
883 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
884 NOTE_BASIC_BLOCK (cur_insn) = bb;
887 /* Perform sanity checks on the insn chain.
888 1. Check that next/prev pointers are consistent in both the forward and
890 2. Count insns in chain, going both directions, and check if equal.
891 3. Check that get_last_insn () returns the actual end of chain. */
894 verify_insn_chain (void)
897 int insn_cnt1, insn_cnt2;
899 for (prevx = NULL, insn_cnt1 = 1, x = get_insns ();
901 prevx = x, insn_cnt1++, x = NEXT_INSN (x))
902 gcc_assert (PREV_INSN (x) == prevx);
904 gcc_assert (prevx == get_last_insn ());
906 for (nextx = NULL, insn_cnt2 = 1, x = get_last_insn ();
908 nextx = x, insn_cnt2++, x = PREV_INSN (x))
909 gcc_assert (NEXT_INSN (x) == nextx);
911 gcc_assert (insn_cnt1 == insn_cnt2);
914 /* If we have assembler epilogues, the block falling through to exit must
915 be the last one in the reordered chain when we reach final. Ensure
916 that this condition is met. */
918 fixup_fallthru_exit_predecessor (void)
922 basic_block bb = NULL;
924 /* This transformation is not valid before reload, because we might
925 separate a call from the instruction that copies the return
927 gcc_assert (reload_completed);
929 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
930 if (e->flags & EDGE_FALLTHRU)
933 if (bb && bb->rbi->next)
935 basic_block c = ENTRY_BLOCK_PTR->next_bb;
937 /* If the very first block is the one with the fall-through exit
938 edge, we have to split that block. */
941 bb = split_block (bb, NULL)->dest;
942 initialize_bb_rbi (bb);
943 bb->rbi->next = c->rbi->next;
945 bb->rbi->footer = c->rbi->footer;
946 c->rbi->footer = NULL;
949 while (c->rbi->next != bb)
952 c->rbi->next = bb->rbi->next;
957 bb->rbi->next = NULL;
961 /* Return true in case it is possible to duplicate the basic block BB. */
963 /* We do not want to declare the function in a header file, since it should
964 only be used through the cfghooks interface, and we do not want to move
965 it to cfgrtl.c since it would require also moving quite a lot of related
967 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
970 cfg_layout_can_duplicate_bb_p (basic_block bb)
972 /* Do not attempt to duplicate tablejumps, as we need to unshare
973 the dispatch table. This is difficult to do, as the instructions
974 computing jump destination may be hoisted outside the basic block. */
975 if (tablejump_p (BB_END (bb), NULL, NULL))
978 /* Do not duplicate blocks containing insns that can't be copied. */
979 if (targetm.cannot_copy_insn_p)
981 rtx insn = BB_HEAD (bb);
984 if (INSN_P (insn) && targetm.cannot_copy_insn_p (insn))
986 if (insn == BB_END (bb))
988 insn = NEXT_INSN (insn);
996 duplicate_insn_chain (rtx from, rtx to)
1000 /* Avoid updating of boundaries of previous basic block. The
1001 note will get removed from insn stream in fixup. */
1002 last = emit_note (NOTE_INSN_DELETED);
1004 /* Create copy at the end of INSN chain. The chain will
1005 be reordered later. */
1006 for (insn = from; insn != NEXT_INSN (to); insn = NEXT_INSN (insn))
1008 switch (GET_CODE (insn))
1013 /* Avoid copying of dispatch tables. We never duplicate
1014 tablejumps, so this can hit only in case the table got
1015 moved far from original jump. */
1016 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
1017 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
1019 emit_copy_of_insn_after (insn, get_last_insn ());
1030 switch (NOTE_LINE_NUMBER (insn))
1032 /* In case prologue is empty and function contain label
1033 in first BB, we may want to copy the block. */
1034 case NOTE_INSN_PROLOGUE_END:
1036 case NOTE_INSN_LOOP_BEG:
1037 case NOTE_INSN_LOOP_END:
1038 /* Strip down the loop notes - we don't really want to keep
1039 them consistent in loop copies. */
1040 case NOTE_INSN_DELETED:
1041 case NOTE_INSN_DELETED_LABEL:
1042 /* No problem to strip these. */
1043 case NOTE_INSN_EPILOGUE_BEG:
1044 case NOTE_INSN_FUNCTION_END:
1045 /* Debug code expect these notes to exist just once.
1046 Keep them in the master copy.
1047 ??? It probably makes more sense to duplicate them for each
1049 case NOTE_INSN_FUNCTION_BEG:
1050 /* There is always just single entry to function. */
1051 case NOTE_INSN_BASIC_BLOCK:
1054 case NOTE_INSN_REPEATED_LINE_NUMBER:
1055 case NOTE_INSN_UNLIKELY_EXECUTED_CODE:
1056 emit_note_copy (insn);
1060 /* All other notes should have already been eliminated.
1062 gcc_assert (NOTE_LINE_NUMBER (insn) >= 0);
1064 /* It is possible that no_line_number is set and the note
1065 won't be emitted. */
1066 emit_note_copy (insn);
1073 insn = NEXT_INSN (last);
1077 /* Create a duplicate of the basic block BB. */
1079 /* We do not want to declare the function in a header file, since it should
1080 only be used through the cfghooks interface, and we do not want to move
1081 it to cfgrtl.c since it would require also moving quite a lot of related
1083 extern basic_block cfg_layout_duplicate_bb (basic_block);
1086 cfg_layout_duplicate_bb (basic_block bb)
1091 insn = duplicate_insn_chain (BB_HEAD (bb), BB_END (bb));
1092 new_bb = create_basic_block (insn,
1093 insn ? get_last_insn () : NULL,
1094 EXIT_BLOCK_PTR->prev_bb);
1096 BB_COPY_PARTITION (new_bb, bb);
1097 if (bb->rbi->header)
1099 insn = bb->rbi->header;
1100 while (NEXT_INSN (insn))
1101 insn = NEXT_INSN (insn);
1102 insn = duplicate_insn_chain (bb->rbi->header, insn);
1104 new_bb->rbi->header = unlink_insn_chain (insn, get_last_insn ());
1107 if (bb->rbi->footer)
1109 insn = bb->rbi->footer;
1110 while (NEXT_INSN (insn))
1111 insn = NEXT_INSN (insn);
1112 insn = duplicate_insn_chain (bb->rbi->footer, insn);
1114 new_bb->rbi->footer = unlink_insn_chain (insn, get_last_insn ());
1117 if (bb->global_live_at_start)
1119 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (®_obstack);
1120 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (®_obstack);
1121 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_start);
1122 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1128 /* Main entry point to this module - initialize the datastructures for
1129 CFG layout changes. It keeps LOOPS up-to-date if not null.
1131 FLAGS is a set of additional flags to pass to cleanup_cfg(). It should
1132 include CLEANUP_UPDATE_LIFE if liveness information must be kept up
1136 cfg_layout_initialize (unsigned int flags)
1140 /* Our algorithm depends on fact that there are no dead jumptables
1144 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1145 initialize_bb_rbi (bb);
1147 cfg_layout_rtl_register_cfg_hooks ();
1149 record_effective_endpoints ();
1151 cleanup_cfg (CLEANUP_CFGLAYOUT | flags);
1154 /* Splits superblocks. */
1156 break_superblocks (void)
1158 sbitmap superblocks;
1162 superblocks = sbitmap_alloc (last_basic_block);
1163 sbitmap_zero (superblocks);
1166 if (bb->flags & BB_SUPERBLOCK)
1168 bb->flags &= ~BB_SUPERBLOCK;
1169 SET_BIT (superblocks, bb->index);
1175 rebuild_jump_labels (get_insns ());
1176 find_many_sub_basic_blocks (superblocks);
1182 /* Finalize the changes: reorder insn list according to the sequence, enter
1183 compensation code, rebuild scope forest. */
1186 cfg_layout_finalize (void)
1190 #ifdef ENABLE_CHECKING
1191 verify_flow_info ();
1193 rtl_register_cfg_hooks ();
1194 if (reload_completed
1195 #ifdef HAVE_epilogue
1199 fixup_fallthru_exit_predecessor ();
1200 fixup_reorder_chain ();
1202 #ifdef ENABLE_CHECKING
1203 verify_insn_chain ();
1207 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1210 break_superblocks ();
1212 #ifdef ENABLE_CHECKING
1213 verify_flow_info ();
1217 /* Checks whether all N blocks in BBS array can be copied. */
1219 can_copy_bbs_p (basic_block *bbs, unsigned n)
1225 for (i = 0; i < n; i++)
1226 bbs[i]->rbi->duplicated = 1;
1228 for (i = 0; i < n; i++)
1230 /* In case we should redirect abnormal edge during duplication, fail. */
1232 FOR_EACH_EDGE (e, ei, bbs[i]->succs)
1233 if ((e->flags & EDGE_ABNORMAL)
1234 && e->dest->rbi->duplicated)
1240 if (!can_duplicate_block_p (bbs[i]))
1248 for (i = 0; i < n; i++)
1249 bbs[i]->rbi->duplicated = 0;
1254 /* Duplicates N basic blocks stored in array BBS. Newly created basic blocks
1255 are placed into array NEW_BBS in the same order. Edges from basic blocks
1256 in BBS are also duplicated and copies of those of them
1257 that lead into BBS are redirected to appropriate newly created block. The
1258 function assigns bbs into loops (copy of basic block bb is assigned to
1259 bb->loop_father->copy loop, so this must be set up correctly in advance)
1260 and updates dominators locally (LOOPS structure that contains the information
1261 about dominators is passed to enable this).
1263 BASE is the superloop to that basic block belongs; if its header or latch
1264 is copied, we do not set the new blocks as header or latch.
1266 Created copies of N_EDGES edges in array EDGES are stored in array NEW_EDGES,
1267 also in the same order. */
1270 copy_bbs (basic_block *bbs, unsigned n, basic_block *new_bbs,
1271 edge *edges, unsigned n_edges, edge *new_edges,
1275 basic_block bb, new_bb, dom_bb;
1278 /* Duplicate bbs, update dominators, assign bbs to loops. */
1279 for (i = 0; i < n; i++)
1283 new_bb = new_bbs[i] = duplicate_block (bb, NULL);
1284 bb->rbi->duplicated = 1;
1286 add_bb_to_loop (new_bb, bb->loop_father->copy);
1287 /* Possibly set header. */
1288 if (bb->loop_father->header == bb && bb->loop_father != base)
1289 new_bb->loop_father->header = new_bb;
1291 if (bb->loop_father->latch == bb && bb->loop_father != base)
1292 new_bb->loop_father->latch = new_bb;
1295 /* Set dominators. */
1296 for (i = 0; i < n; i++)
1299 new_bb = new_bbs[i];
1301 dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
1302 if (dom_bb->rbi->duplicated)
1304 dom_bb = dom_bb->rbi->copy;
1305 set_immediate_dominator (CDI_DOMINATORS, new_bb, dom_bb);
1309 /* Redirect edges. */
1310 for (j = 0; j < n_edges; j++)
1311 new_edges[j] = NULL;
1312 for (i = 0; i < n; i++)
1315 new_bb = new_bbs[i];
1318 FOR_EACH_EDGE (e, ei, new_bb->succs)
1320 for (j = 0; j < n_edges; j++)
1321 if (edges[j] && edges[j]->src == bb && edges[j]->dest == e->dest)
1324 if (!e->dest->rbi->duplicated)
1326 redirect_edge_and_branch_force (e, e->dest->rbi->copy);
1330 /* Clear information about duplicates. */
1331 for (i = 0; i < n; i++)
1332 bbs[i]->rbi->duplicated = 0;
1335 #include "gt-cfglayout.h"