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 e_fall->flags &= ~EDGE_FALLTHRU;
718 e_taken->flags |= EDGE_FALLTHRU;
719 update_br_prob_note (bb);
720 e = e_fall, e_fall = e_taken, e_taken = e;
724 /* If the "jumping" edge is a crossing edge, and the fall
725 through edge is non-crossing, leave things as they are. */
726 else if (e_taken->crossing_edge && !e_fall->crossing_edge)
729 /* Otherwise we can try to invert the jump. This will
730 basically never fail, however, keep up the pretense. */
731 else if (invert_jump (bb_end_insn,
732 label_for_bb (e_fall->dest), 0))
734 e_fall->flags &= ~EDGE_FALLTHRU;
735 e_taken->flags |= EDGE_FALLTHRU;
736 update_br_prob_note (bb);
740 else if (returnjump_p (bb_end_insn))
744 /* Otherwise we have some switch or computed jump. In the
745 99% case, there should not have been a fallthru edge. */
749 #ifdef CASE_DROPS_THROUGH
750 /* Except for VAX. Since we didn't have predication for the
751 tablejump, the fallthru block should not have moved. */
752 if (bb->rbi->next == e_fall->dest)
754 bb_end_insn = skip_insns_after_block (bb);
762 /* No fallthru implies a noreturn function with EH edges, or
763 something similarly bizarre. In any case, we don't need to
768 /* If the fallthru block is still next, nothing to do. */
769 if (bb->rbi->next == e_fall->dest)
772 /* A fallthru to exit block. */
773 if (!bb->rbi->next && e_fall->dest == EXIT_BLOCK_PTR)
777 /* We got here if we need to add a new jump insn. */
778 nb = force_nonfallthru (e_fall);
781 initialize_bb_rbi (nb);
782 nb->rbi->visited = 1;
783 nb->rbi->next = bb->rbi->next;
785 /* Don't process this new block. */
789 /* Make sure new bb is tagged for correct section (same as
790 fall-thru source). */
791 e_fall->src->partition = bb->pred->src->partition;
792 if (flag_reorder_blocks_and_partition)
794 if (bb->pred->src->partition == COLD_PARTITION)
797 rtx note = BB_HEAD (e_fall->src);
799 while (!INSN_P (note)
800 && note != BB_END (e_fall->src))
801 note = NEXT_INSN (note);
803 new_note = emit_note_before
804 (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
806 NOTE_BASIC_BLOCK (new_note) = bb;
808 if (GET_CODE (BB_END (bb)) == JUMP_INSN
809 && !any_condjump_p (BB_END (bb))
810 && bb->succ->crossing_edge )
811 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
812 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
817 /* Put basic_block_info in the new order. */
821 fprintf (dump_file, "Reordered sequence:\n");
822 for (bb = ENTRY_BLOCK_PTR->next_bb, index = 0;
824 bb = bb->rbi->next, index++)
826 fprintf (dump_file, " %i ", index);
827 if (bb->rbi->original)
828 fprintf (dump_file, "duplicate of %i ",
829 bb->rbi->original->index);
830 else if (forwarder_block_p (bb)
831 && GET_CODE (BB_HEAD (bb)) != CODE_LABEL)
832 fprintf (dump_file, "compensation ");
834 fprintf (dump_file, "bb %i ", bb->index);
835 fprintf (dump_file, " [%i]\n", bb->frequency);
839 prev_bb = ENTRY_BLOCK_PTR;
840 bb = ENTRY_BLOCK_PTR->next_bb;
843 for (; bb; prev_bb = bb, bb = bb->rbi->next, index ++)
846 BASIC_BLOCK (index) = bb;
848 update_unlikely_executed_notes (bb);
850 bb->prev_bb = prev_bb;
851 prev_bb->next_bb = bb;
853 prev_bb->next_bb = EXIT_BLOCK_PTR;
854 EXIT_BLOCK_PTR->prev_bb = prev_bb;
856 /* Annoying special case - jump around dead jumptables left in the code. */
860 for (e = bb->succ; e && !(e->flags & EDGE_FALLTHRU); e = e->succ_next)
862 if (e && !can_fallthru (e->src, e->dest))
863 force_nonfallthru (e);
867 /* Update the basic block number information in any
868 NOTE_INSN_UNLIKELY_EXECUTED_CODE notes within the basic block. */
871 update_unlikely_executed_notes (basic_block bb)
875 for (cur_insn = BB_HEAD (bb); cur_insn != BB_END (bb);
876 cur_insn = NEXT_INSN (cur_insn))
877 if (GET_CODE (cur_insn) == NOTE
878 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
879 NOTE_BASIC_BLOCK (cur_insn) = bb;
882 /* Perform sanity checks on the insn chain.
883 1. Check that next/prev pointers are consistent in both the forward and
885 2. Count insns in chain, going both directions, and check if equal.
886 3. Check that get_last_insn () returns the actual end of chain. */
889 verify_insn_chain (void)
892 int insn_cnt1, insn_cnt2;
894 for (prevx = NULL, insn_cnt1 = 1, x = get_insns ();
896 prevx = x, insn_cnt1++, x = NEXT_INSN (x))
897 if (PREV_INSN (x) != prevx)
900 if (prevx != get_last_insn ())
903 for (nextx = NULL, insn_cnt2 = 1, x = get_last_insn ();
905 nextx = x, insn_cnt2++, x = PREV_INSN (x))
906 if (NEXT_INSN (x) != nextx)
909 if (insn_cnt1 != insn_cnt2)
913 /* The block falling through to exit must be the last one in the
914 reordered chain. Ensure that this condition is met. */
916 fixup_fallthru_exit_predecessor (void)
919 basic_block bb = NULL;
921 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
922 if (e->flags & EDGE_FALLTHRU)
925 if (bb && bb->rbi->next)
927 basic_block c = ENTRY_BLOCK_PTR->next_bb;
929 while (c->rbi->next != bb)
932 c->rbi->next = bb->rbi->next;
937 bb->rbi->next = NULL;
941 /* Return true in case it is possible to duplicate the basic block BB. */
943 /* We do not want to declare the function in a header file, since it should
944 only be used through the cfghooks interface, and we do not want to move
945 it to cfgrtl.c since it would require also moving quite a lot of related
947 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
950 cfg_layout_can_duplicate_bb_p (basic_block bb)
952 /* Do not attempt to duplicate tablejumps, as we need to unshare
953 the dispatch table. This is difficult to do, as the instructions
954 computing jump destination may be hoisted outside the basic block. */
955 if (tablejump_p (BB_END (bb), NULL, NULL))
958 /* Do not duplicate blocks containing insns that can't be copied. */
959 if (targetm.cannot_copy_insn_p)
961 rtx insn = BB_HEAD (bb);
964 if (INSN_P (insn) && targetm.cannot_copy_insn_p (insn))
966 if (insn == BB_END (bb))
968 insn = NEXT_INSN (insn);
976 duplicate_insn_chain (rtx from, rtx to)
980 /* Avoid updating of boundaries of previous basic block. The
981 note will get removed from insn stream in fixup. */
982 last = emit_note (NOTE_INSN_DELETED);
984 /* Create copy at the end of INSN chain. The chain will
985 be reordered later. */
986 for (insn = from; insn != NEXT_INSN (to); insn = NEXT_INSN (insn))
988 switch (GET_CODE (insn))
993 /* Avoid copying of dispatch tables. We never duplicate
994 tablejumps, so this can hit only in case the table got
995 moved far from original jump. */
996 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
997 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
999 emit_copy_of_insn_after (insn, get_last_insn ());
1010 switch (NOTE_LINE_NUMBER (insn))
1012 /* In case prologue is empty and function contain label
1013 in first BB, we may want to copy the block. */
1014 case NOTE_INSN_PROLOGUE_END:
1016 case NOTE_INSN_LOOP_VTOP:
1017 case NOTE_INSN_LOOP_CONT:
1018 case NOTE_INSN_LOOP_BEG:
1019 case NOTE_INSN_LOOP_END:
1020 /* Strip down the loop notes - we don't really want to keep
1021 them consistent in loop copies. */
1022 case NOTE_INSN_DELETED:
1023 case NOTE_INSN_DELETED_LABEL:
1024 /* No problem to strip these. */
1025 case NOTE_INSN_EPILOGUE_BEG:
1026 case NOTE_INSN_FUNCTION_END:
1027 /* Debug code expect these notes to exist just once.
1028 Keep them in the master copy.
1029 ??? It probably makes more sense to duplicate them for each
1031 case NOTE_INSN_FUNCTION_BEG:
1032 /* There is always just single entry to function. */
1033 case NOTE_INSN_BASIC_BLOCK:
1036 /* There is no purpose to duplicate prologue. */
1037 case NOTE_INSN_BLOCK_BEG:
1038 case NOTE_INSN_BLOCK_END:
1039 /* The BLOCK_BEG/BLOCK_END notes should be eliminated when BB
1040 reordering is in the progress. */
1041 case NOTE_INSN_EH_REGION_BEG:
1042 case NOTE_INSN_EH_REGION_END:
1043 /* Should never exist at BB duplication time. */
1046 case NOTE_INSN_REPEATED_LINE_NUMBER:
1047 case NOTE_INSN_UNLIKELY_EXECUTED_CODE:
1048 emit_note_copy (insn);
1052 if (NOTE_LINE_NUMBER (insn) < 0)
1054 /* It is possible that no_line_number is set and the note
1055 won't be emitted. */
1056 emit_note_copy (insn);
1063 insn = NEXT_INSN (last);
1067 /* Create a duplicate of the basic block BB. */
1069 /* We do not want to declare the function in a header file, since it should
1070 only be used through the cfghooks interface, and we do not want to move
1071 it to cfgrtl.c since it would require also moving quite a lot of related
1073 extern basic_block cfg_layout_duplicate_bb (basic_block);
1076 cfg_layout_duplicate_bb (basic_block bb)
1081 insn = duplicate_insn_chain (BB_HEAD (bb), BB_END (bb));
1082 new_bb = create_basic_block (insn,
1083 insn ? get_last_insn () : NULL,
1084 EXIT_BLOCK_PTR->prev_bb);
1086 if (bb->rbi->header)
1088 insn = bb->rbi->header;
1089 while (NEXT_INSN (insn))
1090 insn = NEXT_INSN (insn);
1091 insn = duplicate_insn_chain (bb->rbi->header, insn);
1093 new_bb->rbi->header = unlink_insn_chain (insn, get_last_insn ());
1096 if (bb->rbi->footer)
1098 insn = bb->rbi->footer;
1099 while (NEXT_INSN (insn))
1100 insn = NEXT_INSN (insn);
1101 insn = duplicate_insn_chain (bb->rbi->footer, insn);
1103 new_bb->rbi->footer = unlink_insn_chain (insn, get_last_insn ());
1106 if (bb->global_live_at_start)
1108 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1109 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1110 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_start);
1111 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1117 /* Main entry point to this module - initialize the data structures for
1118 CFG layout changes. It keeps LOOPS up-to-date if not null. */
1121 cfg_layout_initialize (void)
1125 /* Our algorithm depends on fact that there are no dead jumptables
1129 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1130 initialize_bb_rbi (bb);
1132 cfg_layout_rtl_register_cfg_hooks ();
1134 record_effective_endpoints ();
1136 cleanup_cfg (CLEANUP_CFGLAYOUT);
1139 /* Splits superblocks. */
1141 break_superblocks (void)
1143 sbitmap superblocks;
1147 superblocks = sbitmap_alloc (last_basic_block);
1148 sbitmap_zero (superblocks);
1151 if (bb->flags & BB_SUPERBLOCK)
1153 bb->flags &= ~BB_SUPERBLOCK;
1154 SET_BIT (superblocks, bb->index);
1160 rebuild_jump_labels (get_insns ());
1161 find_many_sub_basic_blocks (superblocks);
1167 /* Finalize the changes: reorder insn list according to the sequence, enter
1168 compensation code, rebuild scope forest. */
1171 cfg_layout_finalize (void)
1175 #ifdef ENABLE_CHECKING
1176 verify_flow_info ();
1178 rtl_register_cfg_hooks ();
1179 fixup_fallthru_exit_predecessor ();
1180 fixup_reorder_chain ();
1182 #ifdef ENABLE_CHECKING
1183 verify_insn_chain ();
1187 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1190 break_superblocks ();
1192 #ifdef ENABLE_CHECKING
1193 verify_flow_info ();
1197 /* Checks whether all N blocks in BBS array can be copied. */
1199 can_copy_bbs_p (basic_block *bbs, unsigned n)
1205 for (i = 0; i < n; i++)
1206 bbs[i]->rbi->duplicated = 1;
1208 for (i = 0; i < n; i++)
1210 /* In case we should redirect abnormal edge during duplication, fail. */
1211 for (e = bbs[i]->succ; e; e = e->succ_next)
1212 if ((e->flags & EDGE_ABNORMAL)
1213 && e->dest->rbi->duplicated)
1219 if (!can_duplicate_block_p (bbs[i]))
1227 for (i = 0; i < n; i++)
1228 bbs[i]->rbi->duplicated = 0;
1233 /* Duplicates N basic blocks stored in array BBS. Newly created basic blocks
1234 are placed into array NEW_BBS in the same order. Edges from basic blocks
1235 in BBS are also duplicated and copies of those of them
1236 that lead into BBS are redirected to appropriate newly created block. The
1237 function assigns bbs into loops (copy of basic block bb is assigned to
1238 bb->loop_father->copy loop, so this must be set up correctly in advance)
1239 and updates dominators locally (LOOPS structure that contains the information
1240 about dominators is passed to enable this).
1242 BASE is the superloop to that basic block belongs; if its header or latch
1243 is copied, we do not set the new blocks as header or latch.
1245 Created copies of N_EDGES edges in array EDGES are stored in array NEW_EDGES,
1246 also in the same order. */
1249 copy_bbs (basic_block *bbs, unsigned n, basic_block *new_bbs,
1250 edge *edges, unsigned n_edges, edge *new_edges,
1254 basic_block bb, new_bb, dom_bb;
1257 /* Duplicate bbs, update dominators, assign bbs to loops. */
1258 for (i = 0; i < n; i++)
1262 new_bb = new_bbs[i] = duplicate_block (bb, NULL);
1263 bb->rbi->duplicated = 1;
1265 add_bb_to_loop (new_bb, bb->loop_father->copy);
1266 /* Possibly set header. */
1267 if (bb->loop_father->header == bb && bb->loop_father != base)
1268 new_bb->loop_father->header = new_bb;
1270 if (bb->loop_father->latch == bb && bb->loop_father != base)
1271 new_bb->loop_father->latch = new_bb;
1274 /* Set dominators. */
1275 for (i = 0; i < n; i++)
1278 new_bb = new_bbs[i];
1280 dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
1281 if (dom_bb->rbi->duplicated)
1283 dom_bb = dom_bb->rbi->copy;
1284 set_immediate_dominator (CDI_DOMINATORS, new_bb, dom_bb);
1288 /* Redirect edges. */
1289 for (j = 0; j < n_edges; j++)
1290 new_edges[j] = NULL;
1291 for (i = 0; i < n; i++)
1293 new_bb = new_bbs[i];
1296 for (e = new_bb->succ; e; e = e->succ_next)
1298 for (j = 0; j < n_edges; j++)
1299 if (edges[j] && edges[j]->src == bb && edges[j]->dest == e->dest)
1302 if (!e->dest->rbi->duplicated)
1304 redirect_edge_and_branch_force (e, e->dest->rbi->copy);
1308 /* Clear information about duplicates. */
1309 for (i = 0; i < n; i++)
1310 bbs[i]->rbi->duplicated = 0;
1313 #include "gt-cfglayout.h"