1 /* Basic block reordering routines for the GNU compiler.
2 Copyright (C) 2000, 2001, 2003, 2004, 2005 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
;
632 if (EDGE_COUNT (bb
->succs
) == 0)
635 /* Find the old fallthru edge, and another non-EH edge for
637 e_taken
= e_fall
= NULL
;
639 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
640 if (e
->flags
& EDGE_FALLTHRU
)
642 else if (! (e
->flags
& EDGE_EH
))
645 bb_end_insn
= BB_END (bb
);
646 if (JUMP_P (bb_end_insn
))
648 if (any_condjump_p (bb_end_insn
))
650 /* If the old fallthru is still next, nothing to do. */
651 if (bb
->rbi
->next
== e_fall
->dest
652 || e_fall
->dest
== EXIT_BLOCK_PTR
)
655 /* The degenerated case of conditional jump jumping to the next
656 instruction can happen on target having jumps with side
659 Create temporarily the duplicated edge representing branch.
660 It will get unidentified by force_nonfallthru_and_redirect
661 that would otherwise get confused by fallthru edge not pointing
662 to the next basic block. */
669 e_fake
= unchecked_make_edge (bb
, e_fall
->dest
, 0);
671 redirected
= redirect_jump (BB_END (bb
),
672 block_label (bb
), 0);
673 gcc_assert (redirected
);
675 note
= find_reg_note (BB_END (bb
), REG_BR_PROB
, NULL_RTX
);
678 int prob
= INTVAL (XEXP (note
, 0));
680 e_fake
->probability
= prob
;
681 e_fake
->count
= e_fall
->count
* prob
/ REG_BR_PROB_BASE
;
682 e_fall
->probability
-= e_fall
->probability
;
683 e_fall
->count
-= e_fake
->count
;
684 if (e_fall
->probability
< 0)
685 e_fall
->probability
= 0;
686 if (e_fall
->count
< 0)
690 /* There is one special case: if *neither* block is next,
691 such as happens at the very end of a function, then we'll
692 need to add a new unconditional jump. Choose the taken
693 edge based on known or assumed probability. */
694 else if (bb
->rbi
->next
!= e_taken
->dest
)
696 rtx note
= find_reg_note (bb_end_insn
, REG_BR_PROB
, 0);
699 && INTVAL (XEXP (note
, 0)) < REG_BR_PROB_BASE
/ 2
700 && invert_jump (bb_end_insn
,
701 (e_fall
->dest
== EXIT_BLOCK_PTR
703 : label_for_bb (e_fall
->dest
)), 0))
705 e_fall
->flags
&= ~EDGE_FALLTHRU
;
706 #ifdef ENABLE_CHECKING
707 gcc_assert (could_fall_through
708 (e_taken
->src
, e_taken
->dest
));
710 e_taken
->flags
|= EDGE_FALLTHRU
;
711 update_br_prob_note (bb
);
712 e
= e_fall
, e_fall
= e_taken
, e_taken
= e
;
716 /* If the "jumping" edge is a crossing edge, and the fall
717 through edge is non-crossing, leave things as they are. */
718 else if ((e_taken
->flags
& EDGE_CROSSING
)
719 && !(e_fall
->flags
& EDGE_CROSSING
))
722 /* Otherwise we can try to invert the jump. This will
723 basically never fail, however, keep up the pretense. */
724 else if (invert_jump (bb_end_insn
,
725 (e_fall
->dest
== EXIT_BLOCK_PTR
727 : label_for_bb (e_fall
->dest
)), 0))
729 e_fall
->flags
&= ~EDGE_FALLTHRU
;
730 #ifdef ENABLE_CHECKING
731 gcc_assert (could_fall_through
732 (e_taken
->src
, e_taken
->dest
));
734 e_taken
->flags
|= EDGE_FALLTHRU
;
735 update_br_prob_note (bb
);
741 /* Otherwise we have some return, switch or computed
742 jump. In the 99% case, there should not have been a
744 gcc_assert (returnjump_p (bb_end_insn
) || !e_fall
);
750 /* No fallthru implies a noreturn function with EH edges, or
751 something similarly bizarre. In any case, we don't need to
756 /* If the fallthru block is still next, nothing to do. */
757 if (bb
->rbi
->next
== e_fall
->dest
)
760 /* A fallthru to exit block. */
761 if (e_fall
->dest
== EXIT_BLOCK_PTR
)
765 /* We got here if we need to add a new jump insn. */
766 nb
= force_nonfallthru (e_fall
);
769 initialize_bb_rbi (nb
);
770 nb
->rbi
->visited
= 1;
771 nb
->rbi
->next
= bb
->rbi
->next
;
773 /* Don't process this new block. */
776 /* Make sure new bb is tagged for correct section (same as
777 fall-thru source, since you cannot fall-throu across
778 section boundaries). */
779 BB_COPY_PARTITION (e_fall
->src
, single_pred (bb
));
780 if (flag_reorder_blocks_and_partition
781 && targetm
.have_named_sections
)
783 if (BB_PARTITION (single_pred (bb
)) == BB_COLD_PARTITION
)
786 rtx note
= BB_HEAD (e_fall
->src
);
788 while (!INSN_P (note
)
789 && note
!= BB_END (e_fall
->src
))
790 note
= NEXT_INSN (note
);
792 new_note
= emit_note_before
793 (NOTE_INSN_UNLIKELY_EXECUTED_CODE
,
795 NOTE_BASIC_BLOCK (new_note
) = bb
;
797 if (JUMP_P (BB_END (bb
))
798 && !any_condjump_p (BB_END (bb
))
799 && (single_succ_edge (bb
)->flags
& EDGE_CROSSING
))
800 REG_NOTES (BB_END (bb
)) = gen_rtx_EXPR_LIST
801 (REG_CROSSING_JUMP
, NULL_RTX
, REG_NOTES (BB_END (bb
)));
806 /* Put basic_block_info in the new order. */
810 fprintf (dump_file
, "Reordered sequence:\n");
811 for (bb
= ENTRY_BLOCK_PTR
->next_bb
, index
= 0;
813 bb
= bb
->rbi
->next
, index
++)
815 fprintf (dump_file
, " %i ", index
);
816 if (bb
->rbi
->original
)
817 fprintf (dump_file
, "duplicate of %i ",
818 bb
->rbi
->original
->index
);
819 else if (forwarder_block_p (bb
)
820 && !LABEL_P (BB_HEAD (bb
)))
821 fprintf (dump_file
, "compensation ");
823 fprintf (dump_file
, "bb %i ", bb
->index
);
824 fprintf (dump_file
, " [%i]\n", bb
->frequency
);
828 prev_bb
= ENTRY_BLOCK_PTR
;
829 bb
= ENTRY_BLOCK_PTR
->next_bb
;
832 for (; bb
; prev_bb
= bb
, bb
= bb
->rbi
->next
, index
++)
835 BASIC_BLOCK (index
) = bb
;
837 update_unlikely_executed_notes (bb
);
839 bb
->prev_bb
= prev_bb
;
840 prev_bb
->next_bb
= bb
;
842 prev_bb
->next_bb
= EXIT_BLOCK_PTR
;
843 EXIT_BLOCK_PTR
->prev_bb
= prev_bb
;
845 /* Annoying special case - jump around dead jumptables left in the code. */
851 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
852 if (e
->flags
& EDGE_FALLTHRU
)
855 if (e
&& !can_fallthru (e
->src
, e
->dest
))
856 force_nonfallthru (e
);
860 /* Update the basic block number information in any
861 NOTE_INSN_UNLIKELY_EXECUTED_CODE notes within the basic block. */
864 update_unlikely_executed_notes (basic_block bb
)
868 for (cur_insn
= BB_HEAD (bb
); cur_insn
!= BB_END (bb
);
869 cur_insn
= NEXT_INSN (cur_insn
))
870 if (NOTE_P (cur_insn
)
871 && NOTE_LINE_NUMBER (cur_insn
) == NOTE_INSN_UNLIKELY_EXECUTED_CODE
)
872 NOTE_BASIC_BLOCK (cur_insn
) = bb
;
875 /* Perform sanity checks on the insn chain.
876 1. Check that next/prev pointers are consistent in both the forward and
878 2. Count insns in chain, going both directions, and check if equal.
879 3. Check that get_last_insn () returns the actual end of chain. */
882 verify_insn_chain (void)
885 int insn_cnt1
, insn_cnt2
;
887 for (prevx
= NULL
, insn_cnt1
= 1, x
= get_insns ();
889 prevx
= x
, insn_cnt1
++, x
= NEXT_INSN (x
))
890 gcc_assert (PREV_INSN (x
) == prevx
);
892 gcc_assert (prevx
== get_last_insn ());
894 for (nextx
= NULL
, insn_cnt2
= 1, x
= get_last_insn ();
896 nextx
= x
, insn_cnt2
++, x
= PREV_INSN (x
))
897 gcc_assert (NEXT_INSN (x
) == nextx
);
899 gcc_assert (insn_cnt1
== insn_cnt2
);
902 /* If we have assembler epilogues, the block falling through to exit must
903 be the last one in the reordered chain when we reach final. Ensure
904 that this condition is met. */
906 fixup_fallthru_exit_predecessor (void)
910 basic_block bb
= NULL
;
912 /* This transformation is not valid before reload, because we might
913 separate a call from the instruction that copies the return
915 gcc_assert (reload_completed
);
917 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
918 if (e
->flags
& EDGE_FALLTHRU
)
921 if (bb
&& bb
->rbi
->next
)
923 basic_block c
= ENTRY_BLOCK_PTR
->next_bb
;
925 /* If the very first block is the one with the fall-through exit
926 edge, we have to split that block. */
929 bb
= split_block (bb
, NULL
)->dest
;
930 initialize_bb_rbi (bb
);
931 bb
->rbi
->next
= c
->rbi
->next
;
933 bb
->rbi
->footer
= c
->rbi
->footer
;
934 c
->rbi
->footer
= NULL
;
937 while (c
->rbi
->next
!= bb
)
940 c
->rbi
->next
= bb
->rbi
->next
;
945 bb
->rbi
->next
= NULL
;
949 /* Return true in case it is possible to duplicate the basic block BB. */
951 /* We do not want to declare the function in a header file, since it should
952 only be used through the cfghooks interface, and we do not want to move
953 it to cfgrtl.c since it would require also moving quite a lot of related
955 extern bool cfg_layout_can_duplicate_bb_p (basic_block
);
958 cfg_layout_can_duplicate_bb_p (basic_block bb
)
960 /* Do not attempt to duplicate tablejumps, as we need to unshare
961 the dispatch table. This is difficult to do, as the instructions
962 computing jump destination may be hoisted outside the basic block. */
963 if (tablejump_p (BB_END (bb
), NULL
, NULL
))
966 /* Do not duplicate blocks containing insns that can't be copied. */
967 if (targetm
.cannot_copy_insn_p
)
969 rtx insn
= BB_HEAD (bb
);
972 if (INSN_P (insn
) && targetm
.cannot_copy_insn_p (insn
))
974 if (insn
== BB_END (bb
))
976 insn
= NEXT_INSN (insn
);
984 duplicate_insn_chain (rtx from
, rtx to
)
988 /* Avoid updating of boundaries of previous basic block. The
989 note will get removed from insn stream in fixup. */
990 last
= emit_note (NOTE_INSN_DELETED
);
992 /* Create copy at the end of INSN chain. The chain will
993 be reordered later. */
994 for (insn
= from
; insn
!= NEXT_INSN (to
); insn
= NEXT_INSN (insn
))
996 switch (GET_CODE (insn
))
1001 /* Avoid copying of dispatch tables. We never duplicate
1002 tablejumps, so this can hit only in case the table got
1003 moved far from original jump. */
1004 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
1005 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
1007 emit_copy_of_insn_after (insn
, get_last_insn ());
1018 switch (NOTE_LINE_NUMBER (insn
))
1020 /* In case prologue is empty and function contain label
1021 in first BB, we may want to copy the block. */
1022 case NOTE_INSN_PROLOGUE_END
:
1024 case NOTE_INSN_LOOP_BEG
:
1025 case NOTE_INSN_LOOP_END
:
1026 /* Strip down the loop notes - we don't really want to keep
1027 them consistent in loop copies. */
1028 case NOTE_INSN_DELETED
:
1029 case NOTE_INSN_DELETED_LABEL
:
1030 /* No problem to strip these. */
1031 case NOTE_INSN_EPILOGUE_BEG
:
1032 case NOTE_INSN_FUNCTION_END
:
1033 /* Debug code expect these notes to exist just once.
1034 Keep them in the master copy.
1035 ??? It probably makes more sense to duplicate them for each
1037 case NOTE_INSN_FUNCTION_BEG
:
1038 /* There is always just single entry to function. */
1039 case NOTE_INSN_BASIC_BLOCK
:
1042 case NOTE_INSN_REPEATED_LINE_NUMBER
:
1043 case NOTE_INSN_UNLIKELY_EXECUTED_CODE
:
1044 emit_note_copy (insn
);
1048 /* All other notes should have already been eliminated.
1050 gcc_assert (NOTE_LINE_NUMBER (insn
) >= 0);
1052 /* It is possible that no_line_number is set and the note
1053 won't be emitted. */
1054 emit_note_copy (insn
);
1061 insn
= NEXT_INSN (last
);
1065 /* Create a duplicate of the basic block BB. */
1067 /* We do not want to declare the function in a header file, since it should
1068 only be used through the cfghooks interface, and we do not want to move
1069 it to cfgrtl.c since it would require also moving quite a lot of related
1071 extern basic_block
cfg_layout_duplicate_bb (basic_block
);
1074 cfg_layout_duplicate_bb (basic_block bb
)
1079 insn
= duplicate_insn_chain (BB_HEAD (bb
), BB_END (bb
));
1080 new_bb
= create_basic_block (insn
,
1081 insn
? get_last_insn () : NULL
,
1082 EXIT_BLOCK_PTR
->prev_bb
);
1084 BB_COPY_PARTITION (new_bb
, bb
);
1085 if (bb
->rbi
->header
)
1087 insn
= bb
->rbi
->header
;
1088 while (NEXT_INSN (insn
))
1089 insn
= NEXT_INSN (insn
);
1090 insn
= duplicate_insn_chain (bb
->rbi
->header
, insn
);
1092 new_bb
->rbi
->header
= unlink_insn_chain (insn
, get_last_insn ());
1095 if (bb
->rbi
->footer
)
1097 insn
= bb
->rbi
->footer
;
1098 while (NEXT_INSN (insn
))
1099 insn
= NEXT_INSN (insn
);
1100 insn
= duplicate_insn_chain (bb
->rbi
->footer
, insn
);
1102 new_bb
->rbi
->footer
= unlink_insn_chain (insn
, get_last_insn ());
1105 if (bb
->global_live_at_start
)
1107 new_bb
->global_live_at_start
= ALLOC_REG_SET (®_obstack
);
1108 new_bb
->global_live_at_end
= ALLOC_REG_SET (®_obstack
);
1109 COPY_REG_SET (new_bb
->global_live_at_start
, bb
->global_live_at_start
);
1110 COPY_REG_SET (new_bb
->global_live_at_end
, bb
->global_live_at_end
);
1116 /* Main entry point to this module - initialize the datastructures for
1117 CFG layout changes. It keeps LOOPS up-to-date if not null.
1119 FLAGS is a set of additional flags to pass to cleanup_cfg(). It should
1120 include CLEANUP_UPDATE_LIFE if liveness information must be kept up
1124 cfg_layout_initialize (unsigned int flags
)
1128 /* Our algorithm depends on fact that there are no dead jumptables
1132 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1133 initialize_bb_rbi (bb
);
1135 cfg_layout_rtl_register_cfg_hooks ();
1137 record_effective_endpoints ();
1139 cleanup_cfg (CLEANUP_CFGLAYOUT
| flags
);
1142 /* Splits superblocks. */
1144 break_superblocks (void)
1146 sbitmap superblocks
;
1150 superblocks
= sbitmap_alloc (last_basic_block
);
1151 sbitmap_zero (superblocks
);
1154 if (bb
->flags
& BB_SUPERBLOCK
)
1156 bb
->flags
&= ~BB_SUPERBLOCK
;
1157 SET_BIT (superblocks
, bb
->index
);
1163 rebuild_jump_labels (get_insns ());
1164 find_many_sub_basic_blocks (superblocks
);
1170 /* Finalize the changes: reorder insn list according to the sequence, enter
1171 compensation code, rebuild scope forest. */
1174 cfg_layout_finalize (void)
1178 #ifdef ENABLE_CHECKING
1179 verify_flow_info ();
1181 rtl_register_cfg_hooks ();
1182 if (reload_completed
1183 #ifdef HAVE_epilogue
1187 fixup_fallthru_exit_predecessor ();
1188 fixup_reorder_chain ();
1190 #ifdef ENABLE_CHECKING
1191 verify_insn_chain ();
1195 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1198 break_superblocks ();
1200 #ifdef ENABLE_CHECKING
1201 verify_flow_info ();
1205 /* Checks whether all N blocks in BBS array can be copied. */
1207 can_copy_bbs_p (basic_block
*bbs
, unsigned n
)
1213 for (i
= 0; i
< n
; i
++)
1214 bbs
[i
]->rbi
->duplicated
= 1;
1216 for (i
= 0; i
< n
; i
++)
1218 /* In case we should redirect abnormal edge during duplication, fail. */
1220 FOR_EACH_EDGE (e
, ei
, bbs
[i
]->succs
)
1221 if ((e
->flags
& EDGE_ABNORMAL
)
1222 && e
->dest
->rbi
->duplicated
)
1228 if (!can_duplicate_block_p (bbs
[i
]))
1236 for (i
= 0; i
< n
; i
++)
1237 bbs
[i
]->rbi
->duplicated
= 0;
1242 /* Duplicates N basic blocks stored in array BBS. Newly created basic blocks
1243 are placed into array NEW_BBS in the same order. Edges from basic blocks
1244 in BBS are also duplicated and copies of those of them
1245 that lead into BBS are redirected to appropriate newly created block. The
1246 function assigns bbs into loops (copy of basic block bb is assigned to
1247 bb->loop_father->copy loop, so this must be set up correctly in advance)
1248 and updates dominators locally (LOOPS structure that contains the information
1249 about dominators is passed to enable this).
1251 BASE is the superloop to that basic block belongs; if its header or latch
1252 is copied, we do not set the new blocks as header or latch.
1254 Created copies of N_EDGES edges in array EDGES are stored in array NEW_EDGES,
1255 also in the same order. */
1258 copy_bbs (basic_block
*bbs
, unsigned n
, basic_block
*new_bbs
,
1259 edge
*edges
, unsigned n_edges
, edge
*new_edges
,
1263 basic_block bb
, new_bb
, dom_bb
;
1266 /* Duplicate bbs, update dominators, assign bbs to loops. */
1267 for (i
= 0; i
< n
; i
++)
1271 new_bb
= new_bbs
[i
] = duplicate_block (bb
, NULL
);
1272 bb
->rbi
->duplicated
= 1;
1274 add_bb_to_loop (new_bb
, bb
->loop_father
->copy
);
1275 /* Possibly set header. */
1276 if (bb
->loop_father
->header
== bb
&& bb
->loop_father
!= base
)
1277 new_bb
->loop_father
->header
= new_bb
;
1279 if (bb
->loop_father
->latch
== bb
&& bb
->loop_father
!= base
)
1280 new_bb
->loop_father
->latch
= new_bb
;
1283 /* Set dominators. */
1284 for (i
= 0; i
< n
; i
++)
1287 new_bb
= new_bbs
[i
];
1289 dom_bb
= get_immediate_dominator (CDI_DOMINATORS
, bb
);
1290 if (dom_bb
->rbi
->duplicated
)
1292 dom_bb
= dom_bb
->rbi
->copy
;
1293 set_immediate_dominator (CDI_DOMINATORS
, new_bb
, dom_bb
);
1297 /* Redirect edges. */
1298 for (j
= 0; j
< n_edges
; j
++)
1299 new_edges
[j
] = NULL
;
1300 for (i
= 0; i
< n
; i
++)
1303 new_bb
= new_bbs
[i
];
1306 FOR_EACH_EDGE (e
, ei
, new_bb
->succs
)
1308 for (j
= 0; j
< n_edges
; j
++)
1309 if (edges
[j
] && edges
[j
]->src
== bb
&& edges
[j
]->dest
== e
->dest
)
1312 if (!e
->dest
->rbi
->duplicated
)
1314 redirect_edge_and_branch_force (e
, e
->dest
->rbi
->copy
);
1318 /* Clear information about duplicates. */
1319 for (i
= 0; i
< n
; i
++)
1320 bbs
[i
]->rbi
->duplicated
= 0;
1323 #include "gt-cfglayout.h"