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"
28 #include "basic-block.h"
29 #include "insn-config.h"
33 #include "cfglayout.h"
37 #include "alloc-pool.h"
40 /* The contents of the current function definition are allocated
41 in this obstack, and all are freed at the end of the function. */
42 extern struct obstack flow_obstack;
44 /* Holds the interesting trailing notes for the function. */
45 rtx cfg_layout_function_footer, cfg_layout_function_header;
47 static rtx skip_insns_after_block (basic_block);
48 static void record_effective_endpoints (void);
49 static rtx label_for_bb (basic_block);
50 static void fixup_reorder_chain (void);
52 static void set_block_levels (tree, int);
53 static void change_scope (rtx, tree, tree);
55 void verify_insn_chain (void);
56 static void fixup_fallthru_exit_predecessor (void);
57 static tree insn_scope (rtx);
58 static void update_unlikely_executed_notes (basic_block);
61 unlink_insn_chain (rtx first, rtx last)
63 rtx prevfirst = PREV_INSN (first);
64 rtx nextlast = NEXT_INSN (last);
66 PREV_INSN (first) = NULL;
67 NEXT_INSN (last) = NULL;
69 NEXT_INSN (prevfirst) = nextlast;
71 PREV_INSN (nextlast) = prevfirst;
73 set_last_insn (prevfirst);
75 set_first_insn (nextlast);
79 /* Skip over inter-block insns occurring after BB which are typically
80 associated with BB (e.g., barriers). If there are any such insns,
81 we return the last one. Otherwise, we return the end of BB. */
84 skip_insns_after_block (basic_block bb)
86 rtx insn, last_insn, next_head, prev;
89 if (bb->next_bb != EXIT_BLOCK_PTR)
90 next_head = BB_HEAD (bb->next_bb);
92 for (last_insn = insn = BB_END (bb); (insn = NEXT_INSN (insn)) != 0; )
94 if (insn == next_head)
97 switch (GET_CODE (insn))
104 switch (NOTE_LINE_NUMBER (insn))
106 case NOTE_INSN_LOOP_END:
107 case NOTE_INSN_BLOCK_END:
110 case NOTE_INSN_DELETED:
111 case NOTE_INSN_DELETED_LABEL:
122 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
123 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
124 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
126 insn = NEXT_INSN (insn);
139 /* It is possible to hit contradictory sequence. For instance:
145 Where barrier belongs to jump_insn, but the note does not. This can be
146 created by removing the basic block originally following
147 NOTE_INSN_LOOP_BEG. In such case reorder the notes. */
149 for (insn = last_insn; insn != BB_END (bb); insn = prev)
151 prev = PREV_INSN (insn);
152 if (GET_CODE (insn) == NOTE)
153 switch (NOTE_LINE_NUMBER (insn))
155 case NOTE_INSN_LOOP_END:
156 case NOTE_INSN_BLOCK_END:
157 case NOTE_INSN_DELETED:
158 case NOTE_INSN_DELETED_LABEL:
161 reorder_insns (insn, insn, last_insn);
168 /* Locate or create a label for a given basic block. */
171 label_for_bb (basic_block bb)
173 rtx label = BB_HEAD (bb);
175 if (GET_CODE (label) != CODE_LABEL)
178 fprintf (dump_file, "Emitting label for block %d\n", bb->index);
180 label = block_label (bb);
186 /* Locate the effective beginning and end of the insn chain for each
187 block, as defined by skip_insns_after_block above. */
190 record_effective_endpoints (void)
196 for (insn = get_insns ();
198 && GET_CODE (insn) == NOTE
199 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
200 insn = NEXT_INSN (insn))
203 abort (); /* No basic blocks at all? */
204 if (PREV_INSN (insn))
205 cfg_layout_function_header =
206 unlink_insn_chain (get_insns (), PREV_INSN (insn));
208 cfg_layout_function_header = NULL_RTX;
210 next_insn = get_insns ();
215 if (PREV_INSN (BB_HEAD (bb)) && next_insn != BB_HEAD (bb))
216 bb->rbi->header = unlink_insn_chain (next_insn,
217 PREV_INSN (BB_HEAD (bb)));
218 end = skip_insns_after_block (bb);
219 if (NEXT_INSN (BB_END (bb)) && BB_END (bb) != end)
220 bb->rbi->footer = unlink_insn_chain (NEXT_INSN (BB_END (bb)), end);
221 next_insn = NEXT_INSN (BB_END (bb));
224 cfg_layout_function_footer = next_insn;
225 if (cfg_layout_function_footer)
226 cfg_layout_function_footer = unlink_insn_chain (cfg_layout_function_footer, get_last_insn ());
229 /* Data structures representing mapping of INSN_LOCATOR into scope blocks, line
230 numbers and files. In order to be GGC friendly we need to use separate
231 varrays. This also slightly improve the memory locality in binary search.
232 The _locs array contains locators where the given property change. The
233 block_locators_blocks contains the scope block that is used for all insn
234 locator greater than corresponding block_locators_locs value and smaller
235 than the following one. Similarly for the other properties. */
236 static GTY(()) varray_type block_locators_locs;
237 static GTY(()) varray_type block_locators_blocks;
238 static GTY(()) varray_type line_locators_locs;
239 static GTY(()) varray_type line_locators_lines;
240 static GTY(()) varray_type file_locators_locs;
241 static GTY(()) varray_type file_locators_files;
242 int prologue_locator;
243 int epilogue_locator;
245 /* During the RTL expansion the lexical blocks and line numbers are
246 represented via INSN_NOTEs. Replace them by representation using
250 insn_locators_initialize (void)
253 tree last_block = NULL;
256 int line_number = 0, last_line_number = 0;
257 char *file_name = NULL, *last_file_name = NULL;
259 prologue_locator = epilogue_locator = 0;
261 VARRAY_INT_INIT (block_locators_locs, 32, "block_locators_locs");
262 VARRAY_TREE_INIT (block_locators_blocks, 32, "block_locators_blocks");
263 VARRAY_INT_INIT (line_locators_locs, 32, "line_locators_locs");
264 VARRAY_INT_INIT (line_locators_lines, 32, "line_locators_lines");
265 VARRAY_INT_INIT (file_locators_locs, 32, "file_locators_locs");
266 VARRAY_CHAR_PTR_INIT (file_locators_files, 32, "file_locators_files");
268 for (insn = get_insns (); insn; insn = next)
270 next = NEXT_INSN (insn);
272 if ((active_insn_p (insn)
273 && GET_CODE (PATTERN (insn)) != ADDR_VEC
274 && GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC)
276 || (!prologue_locator && file_name))
278 if (last_block != block)
281 VARRAY_PUSH_INT (block_locators_locs, loc);
282 VARRAY_PUSH_TREE (block_locators_blocks, block);
285 if (last_line_number != line_number)
288 VARRAY_PUSH_INT (line_locators_locs, loc);
289 VARRAY_PUSH_INT (line_locators_lines, line_number);
290 last_line_number = line_number;
292 if (last_file_name != file_name)
295 VARRAY_PUSH_INT (file_locators_locs, loc);
296 VARRAY_PUSH_CHAR_PTR (file_locators_files, file_name);
297 last_file_name = file_name;
300 if (!prologue_locator && file_name)
301 prologue_locator = loc;
302 if (!NEXT_INSN (insn))
303 epilogue_locator = loc;
304 if (active_insn_p (insn))
305 INSN_LOCATOR (insn) = loc;
306 else if (GET_CODE (insn) == NOTE)
308 switch (NOTE_LINE_NUMBER (insn))
310 case NOTE_INSN_BLOCK_BEG:
311 if (cfun->dont_emit_block_notes)
313 block = NOTE_BLOCK (insn);
316 case NOTE_INSN_BLOCK_END:
317 if (cfun->dont_emit_block_notes)
319 block = BLOCK_SUPERCONTEXT (block);
320 if (block && TREE_CODE (block) == FUNCTION_DECL)
325 if (NOTE_LINE_NUMBER (insn) > 0)
327 line_number = NOTE_LINE_NUMBER (insn);
328 file_name = (char *)NOTE_SOURCE_FILE (insn);
334 if (cfun->dont_emit_block_notes)
335 check_block_change (insn, &block);
338 /* Tag the blocks with a depth number so that change_scope can find
339 the common parent easily. */
340 set_block_levels (DECL_INITIAL (cfun->decl), 0);
342 if (cfun->dont_emit_block_notes)
343 free_block_changes ();
346 /* For each lexical block, set BLOCK_NUMBER to the depth at which it is
347 found in the block tree. */
350 set_block_levels (tree block, int level)
354 BLOCK_NUMBER (block) = level;
355 set_block_levels (BLOCK_SUBBLOCKS (block), level + 1);
356 block = BLOCK_CHAIN (block);
360 /* Return sope resulting from combination of S1 and S2. */
362 choose_inner_scope (tree s1, tree s2)
368 if (BLOCK_NUMBER (s1) > BLOCK_NUMBER (s2))
373 /* Emit lexical block notes needed to change scope from S1 to S2. */
376 change_scope (rtx orig_insn, tree s1, tree s2)
378 rtx insn = orig_insn;
379 tree com = NULL_TREE;
380 tree ts1 = s1, ts2 = s2;
385 if (ts1 == NULL || ts2 == NULL)
387 if (BLOCK_NUMBER (ts1) > BLOCK_NUMBER (ts2))
388 ts1 = BLOCK_SUPERCONTEXT (ts1);
389 else if (BLOCK_NUMBER (ts1) < BLOCK_NUMBER (ts2))
390 ts2 = BLOCK_SUPERCONTEXT (ts2);
393 ts1 = BLOCK_SUPERCONTEXT (ts1);
394 ts2 = BLOCK_SUPERCONTEXT (ts2);
403 rtx note = emit_note_before (NOTE_INSN_BLOCK_END, insn);
404 NOTE_BLOCK (note) = s;
405 s = BLOCK_SUPERCONTEXT (s);
412 insn = emit_note_before (NOTE_INSN_BLOCK_BEG, insn);
413 NOTE_BLOCK (insn) = s;
414 s = BLOCK_SUPERCONTEXT (s);
418 /* Return lexical scope block insn belong to. */
420 insn_scope (rtx insn)
422 int max = VARRAY_ACTIVE_SIZE (block_locators_locs);
424 int loc = INSN_LOCATOR (insn);
426 /* When block_locators_locs was initialized, the pro- and epilogue
427 insns didn't exist yet and can therefore not be found this way.
428 But we know that they belong to the outer most block of the
430 Without this test, the prologue would be put inside the block of
431 the first valid instruction in the function and when that first
432 insn is part of an inlined function then the low_pc of that
433 inlined function is messed up. Likewise for the epilogue and
434 the last valid instruction. */
435 if (loc == prologue_locator || loc == epilogue_locator)
436 return DECL_INITIAL (cfun->decl);
442 int pos = (min + max) / 2;
443 int tmp = VARRAY_INT (block_locators_locs, pos);
445 if (tmp <= loc && min != pos)
447 else if (tmp > loc && max != pos)
455 return VARRAY_TREE (block_locators_blocks, min);
458 /* Return line number of the statement specified by the locator. */
460 locator_line (int loc)
462 int max = VARRAY_ACTIVE_SIZE (line_locators_locs);
469 int pos = (min + max) / 2;
470 int tmp = VARRAY_INT (line_locators_locs, pos);
472 if (tmp <= loc && min != pos)
474 else if (tmp > loc && max != pos)
482 return VARRAY_INT (line_locators_lines, min);
485 /* Return line number of the statement that produced this insn. */
489 return locator_line (INSN_LOCATOR (insn));
492 /* Return source file of the statement specified by LOC. */
494 locator_file (int loc)
496 int max = VARRAY_ACTIVE_SIZE (file_locators_locs);
503 int pos = (min + max) / 2;
504 int tmp = VARRAY_INT (file_locators_locs, pos);
506 if (tmp <= loc && min != pos)
508 else if (tmp > loc && max != pos)
516 return VARRAY_CHAR_PTR (file_locators_files, min);
519 /* Return source file of the statement that produced this insn. */
523 return locator_file (INSN_LOCATOR (insn));
526 /* Rebuild all the NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes based
527 on the scope tree and the newly reordered instructions. */
530 reemit_insn_block_notes (void)
532 tree cur_block = DECL_INITIAL (cfun->decl);
536 if (!active_insn_p (insn))
537 insn = next_active_insn (insn);
538 for (; insn; insn = next_active_insn (insn))
542 this_block = insn_scope (insn);
543 /* For sequences compute scope resulting from merging all scopes
544 of instructions nested inside. */
545 if (GET_CODE (PATTERN (insn)) == SEQUENCE)
548 rtx body = PATTERN (insn);
551 for (i = 0; i < XVECLEN (body, 0); i++)
552 this_block = choose_inner_scope (this_block,
553 insn_scope (XVECEXP (body, 0, i)));
558 if (this_block != cur_block)
560 change_scope (insn, cur_block, this_block);
561 cur_block = this_block;
565 /* change_scope emits before the insn, not after. */
566 note = emit_note (NOTE_INSN_DELETED);
567 change_scope (note, cur_block, DECL_INITIAL (cfun->decl));
573 /* Given a reorder chain, rearrange the code to match. */
576 fixup_reorder_chain (void)
578 basic_block bb, prev_bb;
582 if (cfg_layout_function_header)
584 set_first_insn (cfg_layout_function_header);
585 insn = cfg_layout_function_header;
586 while (NEXT_INSN (insn))
587 insn = NEXT_INSN (insn);
590 /* First do the bulk reordering -- rechain the blocks without regard to
591 the needed changes to jumps and labels. */
593 for (bb = ENTRY_BLOCK_PTR->next_bb, index = 0;
595 bb = bb->rbi->next, index++)
600 NEXT_INSN (insn) = bb->rbi->header;
602 set_first_insn (bb->rbi->header);
603 PREV_INSN (bb->rbi->header) = insn;
604 insn = bb->rbi->header;
605 while (NEXT_INSN (insn))
606 insn = NEXT_INSN (insn);
609 NEXT_INSN (insn) = BB_HEAD (bb);
611 set_first_insn (BB_HEAD (bb));
612 PREV_INSN (BB_HEAD (bb)) = insn;
616 NEXT_INSN (insn) = bb->rbi->footer;
617 PREV_INSN (bb->rbi->footer) = insn;
618 while (NEXT_INSN (insn))
619 insn = NEXT_INSN (insn);
623 if (index != n_basic_blocks)
626 NEXT_INSN (insn) = cfg_layout_function_footer;
627 if (cfg_layout_function_footer)
628 PREV_INSN (cfg_layout_function_footer) = insn;
630 while (NEXT_INSN (insn))
631 insn = NEXT_INSN (insn);
633 set_last_insn (insn);
634 #ifdef ENABLE_CHECKING
635 verify_insn_chain ();
637 delete_dead_jumptables ();
639 /* Now add jumps and labels as needed to match the blocks new
642 for (bb = ENTRY_BLOCK_PTR->next_bb; bb ; bb = bb->rbi->next)
644 edge e_fall, e_taken, e;
649 if (bb->succ == NULL)
652 /* Find the old fallthru edge, and another non-EH edge for
654 e_taken = e_fall = NULL;
655 for (e = bb->succ; e ; e = e->succ_next)
656 if (e->flags & EDGE_FALLTHRU)
658 else if (! (e->flags & EDGE_EH))
661 bb_end_insn = BB_END (bb);
662 if (GET_CODE (bb_end_insn) == JUMP_INSN)
664 if (any_condjump_p (bb_end_insn))
666 /* If the old fallthru is still next, nothing to do. */
667 if (bb->rbi->next == e_fall->dest
669 && e_fall->dest == EXIT_BLOCK_PTR))
672 /* The degenerated case of conditional jump jumping to the next
673 instruction can happen on target having jumps with side
676 Create temporarily the duplicated edge representing branch.
677 It will get unidentified by force_nonfallthru_and_redirect
678 that would otherwise get confused by fallthru edge not pointing
679 to the next basic block. */
685 e_fake = unchecked_make_edge (bb, e_fall->dest, 0);
687 if (!redirect_jump (BB_END (bb), block_label (bb), 0))
689 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
692 int prob = INTVAL (XEXP (note, 0));
694 e_fake->probability = prob;
695 e_fake->count = e_fall->count * prob / REG_BR_PROB_BASE;
696 e_fall->probability -= e_fall->probability;
697 e_fall->count -= e_fake->count;
698 if (e_fall->probability < 0)
699 e_fall->probability = 0;
700 if (e_fall->count < 0)
704 /* There is one special case: if *neither* block is next,
705 such as happens at the very end of a function, then we'll
706 need to add a new unconditional jump. Choose the taken
707 edge based on known or assumed probability. */
708 else if (bb->rbi->next != e_taken->dest)
710 rtx note = find_reg_note (bb_end_insn, REG_BR_PROB, 0);
713 && INTVAL (XEXP (note, 0)) < REG_BR_PROB_BASE / 2
714 && invert_jump (bb_end_insn,
715 label_for_bb (e_fall->dest), 0))
717 #ifdef ENABLE_CHECKING
718 if (!could_fall_through (e_taken->src, e_taken->dest))
721 e_fall->flags &= ~EDGE_FALLTHRU;
722 e_taken->flags |= EDGE_FALLTHRU;
723 update_br_prob_note (bb);
724 e = e_fall, e_fall = e_taken, e_taken = e;
728 /* If the "jumping" edge is a crossing edge, and the fall
729 through edge is non-crossing, leave things as they are. */
730 else if (e_taken->crossing_edge && !e_fall->crossing_edge)
733 /* Otherwise we can try to invert the jump. This will
734 basically never fail, however, keep up the pretense. */
735 else if (invert_jump (bb_end_insn,
736 label_for_bb (e_fall->dest), 0))
738 #ifdef ENABLE_CHECKING
739 if (!could_fall_through (e_taken->src, e_taken->dest))
742 e_fall->flags &= ~EDGE_FALLTHRU;
743 e_taken->flags |= EDGE_FALLTHRU;
744 update_br_prob_note (bb);
748 else if (returnjump_p (bb_end_insn))
752 /* Otherwise we have some switch or computed jump. In the
753 99% case, there should not have been a fallthru edge. */
757 #ifdef CASE_DROPS_THROUGH
758 /* Except for VAX. Since we didn't have predication for the
759 tablejump, the fallthru block should not have moved. */
760 if (bb->rbi->next == e_fall->dest)
762 bb_end_insn = skip_insns_after_block (bb);
770 /* No fallthru implies a noreturn function with EH edges, or
771 something similarly bizarre. In any case, we don't need to
776 /* If the fallthru block is still next, nothing to do. */
777 if (bb->rbi->next == e_fall->dest)
780 /* A fallthru to exit block. */
781 if (e_fall->dest == EXIT_BLOCK_PTR)
785 /* We got here if we need to add a new jump insn. */
786 nb = force_nonfallthru (e_fall);
789 initialize_bb_rbi (nb);
790 nb->rbi->visited = 1;
791 nb->rbi->next = bb->rbi->next;
793 /* Don't process this new block. */
797 /* Make sure new bb is tagged for correct section (same as
798 fall-thru source). */
799 e_fall->src->partition = bb->pred->src->partition;
800 if (flag_reorder_blocks_and_partition)
802 if (bb->pred->src->partition == COLD_PARTITION)
805 rtx note = BB_HEAD (e_fall->src);
807 while (!INSN_P (note)
808 && note != BB_END (e_fall->src))
809 note = NEXT_INSN (note);
811 new_note = emit_note_before
812 (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
814 NOTE_BASIC_BLOCK (new_note) = bb;
816 if (GET_CODE (BB_END (bb)) == JUMP_INSN
817 && !any_condjump_p (BB_END (bb))
818 && bb->succ->crossing_edge )
819 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
820 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
825 /* Put basic_block_info in the new order. */
829 fprintf (dump_file, "Reordered sequence:\n");
830 for (bb = ENTRY_BLOCK_PTR->next_bb, index = 0;
832 bb = bb->rbi->next, index++)
834 fprintf (dump_file, " %i ", index);
835 if (bb->rbi->original)
836 fprintf (dump_file, "duplicate of %i ",
837 bb->rbi->original->index);
838 else if (forwarder_block_p (bb)
839 && GET_CODE (BB_HEAD (bb)) != CODE_LABEL)
840 fprintf (dump_file, "compensation ");
842 fprintf (dump_file, "bb %i ", bb->index);
843 fprintf (dump_file, " [%i]\n", bb->frequency);
847 prev_bb = ENTRY_BLOCK_PTR;
848 bb = ENTRY_BLOCK_PTR->next_bb;
851 for (; bb; prev_bb = bb, bb = bb->rbi->next, index ++)
854 BASIC_BLOCK (index) = bb;
856 update_unlikely_executed_notes (bb);
858 bb->prev_bb = prev_bb;
859 prev_bb->next_bb = bb;
861 prev_bb->next_bb = EXIT_BLOCK_PTR;
862 EXIT_BLOCK_PTR->prev_bb = prev_bb;
864 /* Annoying special case - jump around dead jumptables left in the code. */
868 for (e = bb->succ; e && !(e->flags & EDGE_FALLTHRU); e = e->succ_next)
870 if (e && !can_fallthru (e->src, e->dest))
871 force_nonfallthru (e);
875 /* Update the basic block number information in any
876 NOTE_INSN_UNLIKELY_EXECUTED_CODE notes within the basic block. */
879 update_unlikely_executed_notes (basic_block bb)
883 for (cur_insn = BB_HEAD (bb); cur_insn != BB_END (bb);
884 cur_insn = NEXT_INSN (cur_insn))
885 if (GET_CODE (cur_insn) == NOTE
886 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
887 NOTE_BASIC_BLOCK (cur_insn) = bb;
890 /* Perform sanity checks on the insn chain.
891 1. Check that next/prev pointers are consistent in both the forward and
893 2. Count insns in chain, going both directions, and check if equal.
894 3. Check that get_last_insn () returns the actual end of chain. */
897 verify_insn_chain (void)
900 int insn_cnt1, insn_cnt2;
902 for (prevx = NULL, insn_cnt1 = 1, x = get_insns ();
904 prevx = x, insn_cnt1++, x = NEXT_INSN (x))
905 if (PREV_INSN (x) != prevx)
908 if (prevx != get_last_insn ())
911 for (nextx = NULL, insn_cnt2 = 1, x = get_last_insn ();
913 nextx = x, insn_cnt2++, x = PREV_INSN (x))
914 if (NEXT_INSN (x) != nextx)
917 if (insn_cnt1 != insn_cnt2)
921 /* If we have assembler epilogues, the block falling through to exit must
922 be the last one in the reordered chain when we reach final. Ensure
923 that this condition is met. */
925 fixup_fallthru_exit_predecessor (void)
928 basic_block bb = NULL;
930 /* This transformation is not valid before reload, because we might separate
931 a call from the instruction that copies the return value. */
932 if (! reload_completed)
935 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
936 if (e->flags & EDGE_FALLTHRU)
939 if (bb && bb->rbi->next)
941 basic_block c = ENTRY_BLOCK_PTR->next_bb;
943 /* If the very first block is the one with the fall-through exit
944 edge, we have to split that block. */
947 bb = split_block (bb, NULL)->dest;
948 initialize_bb_rbi (bb);
949 bb->rbi->next = c->rbi->next;
951 bb->rbi->footer = c->rbi->footer;
952 c->rbi->footer = NULL;
955 while (c->rbi->next != bb)
958 c->rbi->next = bb->rbi->next;
963 bb->rbi->next = NULL;
967 /* Return true in case it is possible to duplicate the basic block BB. */
969 /* We do not want to declare the function in a header file, since it should
970 only be used through the cfghooks interface, and we do not want to move
971 it to cfgrtl.c since it would require also moving quite a lot of related
973 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
976 cfg_layout_can_duplicate_bb_p (basic_block bb)
978 /* Do not attempt to duplicate tablejumps, as we need to unshare
979 the dispatch table. This is difficult to do, as the instructions
980 computing jump destination may be hoisted outside the basic block. */
981 if (tablejump_p (BB_END (bb), NULL, NULL))
984 /* Do not duplicate blocks containing insns that can't be copied. */
985 if (targetm.cannot_copy_insn_p)
987 rtx insn = BB_HEAD (bb);
990 if (INSN_P (insn) && targetm.cannot_copy_insn_p (insn))
992 if (insn == BB_END (bb))
994 insn = NEXT_INSN (insn);
1002 duplicate_insn_chain (rtx from, rtx to)
1006 /* Avoid updating of boundaries of previous basic block. The
1007 note will get removed from insn stream in fixup. */
1008 last = emit_note (NOTE_INSN_DELETED);
1010 /* Create copy at the end of INSN chain. The chain will
1011 be reordered later. */
1012 for (insn = from; insn != NEXT_INSN (to); insn = NEXT_INSN (insn))
1014 switch (GET_CODE (insn))
1019 /* Avoid copying of dispatch tables. We never duplicate
1020 tablejumps, so this can hit only in case the table got
1021 moved far from original jump. */
1022 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
1023 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
1025 emit_copy_of_insn_after (insn, get_last_insn ());
1036 switch (NOTE_LINE_NUMBER (insn))
1038 /* In case prologue is empty and function contain label
1039 in first BB, we may want to copy the block. */
1040 case NOTE_INSN_PROLOGUE_END:
1042 case NOTE_INSN_LOOP_VTOP:
1043 case NOTE_INSN_LOOP_CONT:
1044 case NOTE_INSN_LOOP_BEG:
1045 case NOTE_INSN_LOOP_END:
1046 /* Strip down the loop notes - we don't really want to keep
1047 them consistent in loop copies. */
1048 case NOTE_INSN_DELETED:
1049 case NOTE_INSN_DELETED_LABEL:
1050 /* No problem to strip these. */
1051 case NOTE_INSN_EPILOGUE_BEG:
1052 case NOTE_INSN_FUNCTION_END:
1053 /* Debug code expect these notes to exist just once.
1054 Keep them in the master copy.
1055 ??? It probably makes more sense to duplicate them for each
1057 case NOTE_INSN_FUNCTION_BEG:
1058 /* There is always just single entry to function. */
1059 case NOTE_INSN_BASIC_BLOCK:
1062 /* There is no purpose to duplicate prologue. */
1063 case NOTE_INSN_BLOCK_BEG:
1064 case NOTE_INSN_BLOCK_END:
1065 /* The BLOCK_BEG/BLOCK_END notes should be eliminated when BB
1066 reordering is in the progress. */
1067 case NOTE_INSN_EH_REGION_BEG:
1068 case NOTE_INSN_EH_REGION_END:
1069 /* Should never exist at BB duplication time. */
1072 case NOTE_INSN_REPEATED_LINE_NUMBER:
1073 case NOTE_INSN_UNLIKELY_EXECUTED_CODE:
1074 emit_note_copy (insn);
1078 if (NOTE_LINE_NUMBER (insn) < 0)
1080 /* It is possible that no_line_number is set and the note
1081 won't be emitted. */
1082 emit_note_copy (insn);
1089 insn = NEXT_INSN (last);
1093 /* Create a duplicate of the basic block BB. */
1095 /* We do not want to declare the function in a header file, since it should
1096 only be used through the cfghooks interface, and we do not want to move
1097 it to cfgrtl.c since it would require also moving quite a lot of related
1099 extern basic_block cfg_layout_duplicate_bb (basic_block);
1102 cfg_layout_duplicate_bb (basic_block bb)
1107 insn = duplicate_insn_chain (BB_HEAD (bb), BB_END (bb));
1108 new_bb = create_basic_block (insn,
1109 insn ? get_last_insn () : NULL,
1110 EXIT_BLOCK_PTR->prev_bb);
1112 if (bb->rbi->header)
1114 insn = bb->rbi->header;
1115 while (NEXT_INSN (insn))
1116 insn = NEXT_INSN (insn);
1117 insn = duplicate_insn_chain (bb->rbi->header, insn);
1119 new_bb->rbi->header = unlink_insn_chain (insn, get_last_insn ());
1122 if (bb->rbi->footer)
1124 insn = bb->rbi->footer;
1125 while (NEXT_INSN (insn))
1126 insn = NEXT_INSN (insn);
1127 insn = duplicate_insn_chain (bb->rbi->footer, insn);
1129 new_bb->rbi->footer = unlink_insn_chain (insn, get_last_insn ());
1132 if (bb->global_live_at_start)
1134 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1135 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1136 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_start);
1137 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1143 /* Main entry point to this module - initialize the data structures for
1144 CFG layout changes. It keeps LOOPS up-to-date if not null. */
1147 cfg_layout_initialize (void)
1151 /* Our algorithm depends on fact that there are no dead jumptables
1155 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1156 initialize_bb_rbi (bb);
1158 cfg_layout_rtl_register_cfg_hooks ();
1160 record_effective_endpoints ();
1162 cleanup_cfg (CLEANUP_CFGLAYOUT);
1165 /* Splits superblocks. */
1167 break_superblocks (void)
1169 sbitmap superblocks;
1173 superblocks = sbitmap_alloc (last_basic_block);
1174 sbitmap_zero (superblocks);
1177 if (bb->flags & BB_SUPERBLOCK)
1179 bb->flags &= ~BB_SUPERBLOCK;
1180 SET_BIT (superblocks, bb->index);
1186 rebuild_jump_labels (get_insns ());
1187 find_many_sub_basic_blocks (superblocks);
1193 /* Finalize the changes: reorder insn list according to the sequence, enter
1194 compensation code, rebuild scope forest. */
1197 cfg_layout_finalize (void)
1201 #ifdef ENABLE_CHECKING
1202 verify_flow_info ();
1204 rtl_register_cfg_hooks ();
1205 if (reload_completed
1206 #ifdef HAVE_epilogue
1210 fixup_fallthru_exit_predecessor ();
1211 fixup_reorder_chain ();
1213 #ifdef ENABLE_CHECKING
1214 verify_insn_chain ();
1218 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1221 break_superblocks ();
1223 #ifdef ENABLE_CHECKING
1224 verify_flow_info ();
1228 /* Checks whether all N blocks in BBS array can be copied. */
1230 can_copy_bbs_p (basic_block *bbs, unsigned n)
1236 for (i = 0; i < n; i++)
1237 bbs[i]->rbi->duplicated = 1;
1239 for (i = 0; i < n; i++)
1241 /* In case we should redirect abnormal edge during duplication, fail. */
1242 for (e = bbs[i]->succ; e; e = e->succ_next)
1243 if ((e->flags & EDGE_ABNORMAL)
1244 && e->dest->rbi->duplicated)
1250 if (!can_duplicate_block_p (bbs[i]))
1258 for (i = 0; i < n; i++)
1259 bbs[i]->rbi->duplicated = 0;
1264 /* Duplicates N basic blocks stored in array BBS. Newly created basic blocks
1265 are placed into array NEW_BBS in the same order. Edges from basic blocks
1266 in BBS are also duplicated and copies of those of them
1267 that lead into BBS are redirected to appropriate newly created block. The
1268 function assigns bbs into loops (copy of basic block bb is assigned to
1269 bb->loop_father->copy loop, so this must be set up correctly in advance)
1270 and updates dominators locally (LOOPS structure that contains the information
1271 about dominators is passed to enable this).
1273 BASE is the superloop to that basic block belongs; if its header or latch
1274 is copied, we do not set the new blocks as header or latch.
1276 Created copies of N_EDGES edges in array EDGES are stored in array NEW_EDGES,
1277 also in the same order. */
1280 copy_bbs (basic_block *bbs, unsigned n, basic_block *new_bbs,
1281 edge *edges, unsigned n_edges, edge *new_edges,
1285 basic_block bb, new_bb, dom_bb;
1288 /* Duplicate bbs, update dominators, assign bbs to loops. */
1289 for (i = 0; i < n; i++)
1293 new_bb = new_bbs[i] = duplicate_block (bb, NULL);
1294 bb->rbi->duplicated = 1;
1296 add_bb_to_loop (new_bb, bb->loop_father->copy);
1297 /* Possibly set header. */
1298 if (bb->loop_father->header == bb && bb->loop_father != base)
1299 new_bb->loop_father->header = new_bb;
1301 if (bb->loop_father->latch == bb && bb->loop_father != base)
1302 new_bb->loop_father->latch = new_bb;
1305 /* Set dominators. */
1306 for (i = 0; i < n; i++)
1309 new_bb = new_bbs[i];
1311 dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
1312 if (dom_bb->rbi->duplicated)
1314 dom_bb = dom_bb->rbi->copy;
1315 set_immediate_dominator (CDI_DOMINATORS, new_bb, dom_bb);
1319 /* Redirect edges. */
1320 for (j = 0; j < n_edges; j++)
1321 new_edges[j] = NULL;
1322 for (i = 0; i < n; i++)
1324 new_bb = new_bbs[i];
1327 for (e = new_bb->succ; e; e = e->succ_next)
1329 for (j = 0; j < n_edges; j++)
1330 if (edges[j] && edges[j]->src == bb && edges[j]->dest == e->dest)
1333 if (!e->dest->rbi->duplicated)
1335 redirect_edge_and_branch_force (e, e->dest->rbi->copy);
1339 /* Clear information about duplicates. */
1340 for (i = 0; i < n; i++)
1341 bbs[i]->rbi->duplicated = 0;
1344 #include "gt-cfglayout.h"