1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997
3 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
59 #include "hard-reg-set.h"
61 #include "insn-config.h"
62 #include "insn-attr.h"
71 /* ??? Eventually must record somehow the labels used by jumps
72 from nested functions. */
73 /* Pre-record the next or previous real insn for each label?
74 No, this pass is very fast anyway. */
75 /* Condense consecutive labels?
76 This would make life analysis faster, maybe. */
77 /* Optimize jump y; x: ... y: jumpif... x?
78 Don't know if it is worth bothering with. */
79 /* Optimize two cases of conditional jump to conditional jump?
80 This can never delete any instruction or make anything dead,
81 or even change what is live at any point.
82 So perhaps let combiner do it. */
84 /* Vector indexed by uid.
85 For each CODE_LABEL, index by its uid to get first unconditional jump
86 that jumps to the label.
87 For each JUMP_INSN, index by its uid to get the next unconditional jump
88 that jumps to the same label.
89 Element 0 is the start of a chain of all return insns.
90 (It is safe to use element 0 because insn uid 0 is not used. */
92 static rtx
*jump_chain
;
94 /* Maximum index in jump_chain. */
96 static int max_jump_chain
;
98 /* Indicates whether death notes are significant in cross jump analysis.
99 Normally they are not significant, because of A and B jump to C,
100 and R dies in A, it must die in B. But this might not be true after
101 stack register conversion, and we must compare death notes in that
104 static int cross_jump_death_matters
= 0;
106 static int init_label_info
PARAMS ((rtx
));
107 static void delete_barrier_successors
PARAMS ((rtx
));
108 static void mark_all_labels
PARAMS ((rtx
, int));
109 static rtx delete_unreferenced_labels
PARAMS ((rtx
));
110 static void delete_noop_moves
PARAMS ((rtx
));
111 static int duplicate_loop_exit_test
PARAMS ((rtx
));
112 static void find_cross_jump
PARAMS ((rtx
, rtx
, int, rtx
*, rtx
*));
113 static void do_cross_jump
PARAMS ((rtx
, rtx
, rtx
));
114 static int jump_back_p
PARAMS ((rtx
, rtx
));
115 static int tension_vector_labels
PARAMS ((rtx
, int));
116 static void delete_computation
PARAMS ((rtx
));
117 static void redirect_exp_1
PARAMS ((rtx
*, rtx
, rtx
, rtx
));
118 static int redirect_exp
PARAMS ((rtx
, rtx
, rtx
));
119 static void invert_exp_1
PARAMS ((rtx
));
120 static int invert_exp
PARAMS ((rtx
));
121 static void delete_from_jump_chain
PARAMS ((rtx
));
122 static int delete_labelref_insn
PARAMS ((rtx
, rtx
, int));
123 static void mark_modified_reg
PARAMS ((rtx
, rtx
, void *));
124 static void redirect_tablejump
PARAMS ((rtx
, rtx
));
125 static void jump_optimize_1
PARAMS ((rtx
, int, int, int, int, int));
126 static int returnjump_p_1
PARAMS ((rtx
*, void *));
127 static void delete_prior_computation
PARAMS ((rtx
, rtx
));
129 /* Main external entry point into the jump optimizer. See comments before
130 jump_optimize_1 for descriptions of the arguments. */
132 jump_optimize (f
, cross_jump
, noop_moves
, after_regscan
)
138 jump_optimize_1 (f
, cross_jump
, noop_moves
, after_regscan
, 0, 0);
141 /* Alternate entry into the jump optimizer. This entry point only rebuilds
142 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
145 rebuild_jump_labels (f
)
148 jump_optimize_1 (f
, 0, 0, 0, 1, 0);
151 /* Alternate entry into the jump optimizer. Do only trivial optimizations. */
154 jump_optimize_minimal (f
)
157 jump_optimize_1 (f
, 0, 0, 0, 0, 1);
160 /* Delete no-op jumps and optimize jumps to jumps
161 and jumps around jumps.
162 Delete unused labels and unreachable code.
164 If CROSS_JUMP is 1, detect matching code
165 before a jump and its destination and unify them.
166 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
168 If NOOP_MOVES is nonzero, delete no-op move insns.
170 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
171 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
173 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
174 and JUMP_LABEL field for jumping insns.
176 If `optimize' is zero, don't change any code,
177 just determine whether control drops off the end of the function.
178 This case occurs when we have -W and not -O.
179 It works because `delete_insn' checks the value of `optimize'
180 and refrains from actually deleting when that is 0.
182 If MINIMAL is nonzero, then we only perform trivial optimizations:
184 * Removal of unreachable code after BARRIERs.
185 * Removal of unreferenced CODE_LABELs.
186 * Removal of a jump to the next instruction.
187 * Removal of a conditional jump followed by an unconditional jump
188 to the same target as the conditional jump.
189 * Simplify a conditional jump around an unconditional jump.
190 * Simplify a jump to a jump.
191 * Delete extraneous line number notes.
195 jump_optimize_1 (f
, cross_jump
, noop_moves
, after_regscan
,
196 mark_labels_only
, minimal
)
201 int mark_labels_only
;
204 register rtx insn
, next
;
211 enum rtx_code reversed_code
;
214 cross_jump_death_matters
= (cross_jump
== 2);
215 max_uid
= init_label_info (f
) + 1;
217 /* Leave some extra room for labels and duplicate exit test insns
219 max_jump_chain
= max_uid
* 14 / 10;
220 jump_chain
= (rtx
*) xcalloc (max_jump_chain
, sizeof (rtx
));
222 mark_all_labels (f
, cross_jump
);
224 /* Keep track of labels used from static data; we don't track them
225 closely enough to delete them here, so make sure their reference
226 count doesn't drop to zero. */
228 for (insn
= forced_labels
; insn
; insn
= XEXP (insn
, 1))
229 if (GET_CODE (XEXP (insn
, 0)) == CODE_LABEL
)
230 LABEL_NUSES (XEXP (insn
, 0))++;
232 /* Keep track of labels used for marking handlers for exception
233 regions; they cannot usually be deleted. */
235 for (insn
= exception_handler_labels
; insn
; insn
= XEXP (insn
, 1))
236 if (GET_CODE (XEXP (insn
, 0)) == CODE_LABEL
)
237 LABEL_NUSES (XEXP (insn
, 0))++;
239 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
240 notes and recompute LABEL_NUSES. */
241 if (mark_labels_only
)
244 delete_barrier_successors (f
);
246 last_insn
= delete_unreferenced_labels (f
);
249 delete_noop_moves (f
);
251 /* Now iterate optimizing jumps until nothing changes over one pass. */
253 old_max_reg
= max_reg_num ();
258 for (insn
= f
; insn
; insn
= next
)
261 rtx temp
, temp1
, temp2
= NULL_RTX
;
262 rtx temp4 ATTRIBUTE_UNUSED
;
264 int this_is_any_uncondjump
;
265 int this_is_any_condjump
;
266 int this_is_onlyjump
;
268 next
= NEXT_INSN (insn
);
270 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
271 jump. Try to optimize by duplicating the loop exit test if so.
272 This is only safe immediately after regscan, because it uses
273 the values of regno_first_uid and regno_last_uid. */
274 if (after_regscan
&& GET_CODE (insn
) == NOTE
275 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
276 && (temp1
= next_nonnote_insn (insn
)) != 0
277 && any_uncondjump_p (temp1
)
278 && onlyjump_p (temp1
))
280 temp
= PREV_INSN (insn
);
281 if (duplicate_loop_exit_test (insn
))
284 next
= NEXT_INSN (temp
);
289 if (GET_CODE (insn
) != JUMP_INSN
)
292 this_is_any_condjump
= any_condjump_p (insn
);
293 this_is_any_uncondjump
= any_uncondjump_p (insn
);
294 this_is_onlyjump
= onlyjump_p (insn
);
296 /* Tension the labels in dispatch tables. */
298 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
299 changed
|= tension_vector_labels (PATTERN (insn
), 0);
300 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
301 changed
|= tension_vector_labels (PATTERN (insn
), 1);
303 /* See if this jump goes to another jump and redirect if so. */
304 nlabel
= follow_jumps (JUMP_LABEL (insn
));
305 if (nlabel
!= JUMP_LABEL (insn
))
306 changed
|= redirect_jump (insn
, nlabel
, 1);
308 if (! optimize
|| minimal
)
311 /* If a dispatch table always goes to the same place,
312 get rid of it and replace the insn that uses it. */
314 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
315 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
318 rtx pat
= PATTERN (insn
);
319 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
320 int len
= XVECLEN (pat
, diff_vec_p
);
321 rtx dispatch
= prev_real_insn (insn
);
324 for (i
= 0; i
< len
; i
++)
325 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
326 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
331 && GET_CODE (dispatch
) == JUMP_INSN
332 && JUMP_LABEL (dispatch
) != 0
333 /* Don't mess with a casesi insn.
334 XXX according to the comment before computed_jump_p(),
335 all casesi insns should be a parallel of the jump
336 and a USE of a LABEL_REF. */
337 && ! ((set
= single_set (dispatch
)) != NULL
338 && (GET_CODE (SET_SRC (set
)) == IF_THEN_ELSE
))
339 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
341 redirect_tablejump (dispatch
,
342 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
347 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
349 /* Detect jump to following insn. */
350 if (reallabelprev
== insn
351 && (this_is_any_condjump
|| this_is_any_uncondjump
)
354 next
= next_real_insn (JUMP_LABEL (insn
));
357 /* Remove the "inactive" but "real" insns (i.e. uses and
358 clobbers) in between here and there. */
360 while ((temp
= next_real_insn (temp
)) != next
)
367 /* Detect a conditional jump going to the same place
368 as an immediately following unconditional jump. */
369 else if (this_is_any_condjump
&& this_is_onlyjump
370 && (temp
= next_active_insn (insn
)) != 0
371 && simplejump_p (temp
)
372 && (next_active_insn (JUMP_LABEL (insn
))
373 == next_active_insn (JUMP_LABEL (temp
))))
375 /* Don't mess up test coverage analysis. */
377 if (flag_test_coverage
&& !reload_completed
)
378 for (temp2
= insn
; temp2
!= temp
; temp2
= NEXT_INSN (temp2
))
379 if (GET_CODE (temp2
) == NOTE
&& NOTE_LINE_NUMBER (temp2
) > 0)
384 /* Ensure that we jump to the later of the two labels.
395 If we leave the goto L1, we'll incorrectly leave
396 return-reg dead for TEST true. */
398 temp2
= next_active_insn (JUMP_LABEL (insn
));
400 temp2
= get_last_insn ();
401 if (GET_CODE (temp2
) != CODE_LABEL
)
402 temp2
= prev_label (temp2
);
403 if (temp2
!= JUMP_LABEL (temp
))
404 redirect_jump (temp
, temp2
, 1);
412 /* Detect a conditional jump jumping over an unconditional jump. */
414 else if (this_is_any_condjump
415 && reallabelprev
!= 0
416 && GET_CODE (reallabelprev
) == JUMP_INSN
417 && prev_active_insn (reallabelprev
) == insn
418 && no_labels_between_p (insn
, reallabelprev
)
419 && any_uncondjump_p (reallabelprev
)
420 && onlyjump_p (reallabelprev
))
422 /* When we invert the unconditional jump, we will be
423 decrementing the usage count of its old label.
424 Make sure that we don't delete it now because that
425 might cause the following code to be deleted. */
426 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
427 rtx prev_label
= JUMP_LABEL (insn
);
430 ++LABEL_NUSES (prev_label
);
432 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
), 1))
434 /* It is very likely that if there are USE insns before
435 this jump, they hold REG_DEAD notes. These REG_DEAD
436 notes are no longer valid due to this optimization,
437 and will cause the life-analysis that following passes
438 (notably delayed-branch scheduling) to think that
439 these registers are dead when they are not.
441 To prevent this trouble, we just remove the USE insns
442 from the insn chain. */
444 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
445 && GET_CODE (PATTERN (prev_uses
)) == USE
)
447 rtx useless
= prev_uses
;
448 prev_uses
= prev_nonnote_insn (prev_uses
);
449 delete_insn (useless
);
452 delete_insn (reallabelprev
);
456 /* We can now safely delete the label if it is unreferenced
457 since the delete_insn above has deleted the BARRIER. */
458 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
459 delete_insn (prev_label
);
461 next
= NEXT_INSN (insn
);
464 /* If we have an unconditional jump preceded by a USE, try to put
465 the USE before the target and jump there. This simplifies many
466 of the optimizations below since we don't have to worry about
467 dealing with these USE insns. We only do this if the label
468 being branch to already has the identical USE or if code
469 never falls through to that label. */
471 else if (this_is_any_uncondjump
472 && (temp
= prev_nonnote_insn (insn
)) != 0
473 && GET_CODE (temp
) == INSN
474 && GET_CODE (PATTERN (temp
)) == USE
475 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
476 && (GET_CODE (temp1
) == BARRIER
477 || (GET_CODE (temp1
) == INSN
478 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
))))
479 /* Don't do this optimization if we have a loop containing
480 only the USE instruction, and the loop start label has
481 a usage count of 1. This is because we will redo this
482 optimization everytime through the outer loop, and jump
483 opt will never exit. */
484 && ! ((temp2
= prev_nonnote_insn (temp
)) != 0
485 && temp2
== JUMP_LABEL (insn
)
486 && LABEL_NUSES (temp2
) == 1))
488 if (GET_CODE (temp1
) == BARRIER
)
490 emit_insn_after (PATTERN (temp
), temp1
);
491 temp1
= NEXT_INSN (temp1
);
495 redirect_jump (insn
, get_label_before (temp1
), 1);
496 reallabelprev
= prev_real_insn (temp1
);
498 next
= NEXT_INSN (insn
);
502 /* Detect a conditional jump jumping over an unconditional trap. */
504 && this_is_any_condjump
&& this_is_onlyjump
505 && reallabelprev
!= 0
506 && GET_CODE (reallabelprev
) == INSN
507 && GET_CODE (PATTERN (reallabelprev
)) == TRAP_IF
508 && TRAP_CONDITION (PATTERN (reallabelprev
)) == const_true_rtx
509 && prev_active_insn (reallabelprev
) == insn
510 && no_labels_between_p (insn
, reallabelprev
)
511 && (temp2
= get_condition (insn
, &temp4
))
512 && ((reversed_code
= reversed_comparison_code (temp2
, insn
))
515 rtx
new = gen_cond_trap (reversed_code
,
516 XEXP (temp2
, 0), XEXP (temp2
, 1),
517 TRAP_CODE (PATTERN (reallabelprev
)));
521 emit_insn_before (new, temp4
);
522 delete_insn (reallabelprev
);
528 /* Detect a jump jumping to an unconditional trap. */
529 else if (HAVE_trap
&& this_is_onlyjump
530 && (temp
= next_active_insn (JUMP_LABEL (insn
)))
531 && GET_CODE (temp
) == INSN
532 && GET_CODE (PATTERN (temp
)) == TRAP_IF
533 && (this_is_any_uncondjump
534 || (this_is_any_condjump
535 && (temp2
= get_condition (insn
, &temp4
)))))
537 rtx tc
= TRAP_CONDITION (PATTERN (temp
));
539 if (tc
== const_true_rtx
540 || (! this_is_any_uncondjump
&& rtx_equal_p (temp2
, tc
)))
543 /* Replace an unconditional jump to a trap with a trap. */
544 if (this_is_any_uncondjump
)
546 emit_barrier_after (emit_insn_before (gen_trap (), insn
));
551 new = gen_cond_trap (GET_CODE (temp2
), XEXP (temp2
, 0),
553 TRAP_CODE (PATTERN (temp
)));
556 emit_insn_before (new, temp4
);
562 /* If the trap condition and jump condition are mutually
563 exclusive, redirect the jump to the following insn. */
564 else if (GET_RTX_CLASS (GET_CODE (tc
)) == '<'
565 && this_is_any_condjump
566 && swap_condition (GET_CODE (temp2
)) == GET_CODE (tc
)
567 && rtx_equal_p (XEXP (tc
, 0), XEXP (temp2
, 0))
568 && rtx_equal_p (XEXP (tc
, 1), XEXP (temp2
, 1))
569 && redirect_jump (insn
, get_label_after (temp
), 1))
578 /* Now that the jump has been tensioned,
579 try cross jumping: check for identical code
580 before the jump and before its target label. */
582 /* First, cross jumping of conditional jumps: */
584 if (cross_jump
&& condjump_p (insn
))
586 rtx newjpos
, newlpos
;
587 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
589 /* A conditional jump may be crossjumped
590 only if the place it jumps to follows
591 an opposing jump that comes back here. */
593 if (x
!= 0 && ! jump_back_p (x
, insn
))
594 /* We have no opposing jump;
595 cannot cross jump this insn. */
599 /* TARGET is nonzero if it is ok to cross jump
600 to code before TARGET. If so, see if matches. */
602 find_cross_jump (insn
, x
, 2,
607 do_cross_jump (insn
, newjpos
, newlpos
);
608 /* Make the old conditional jump
609 into an unconditional one. */
610 PATTERN (insn
) = gen_jump (JUMP_LABEL (insn
));
611 INSN_CODE (insn
) = -1;
612 emit_barrier_after (insn
);
613 /* Add to jump_chain unless this is a new label
614 whose UID is too large. */
615 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
617 jump_chain
[INSN_UID (insn
)]
618 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
619 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
626 /* Cross jumping of unconditional jumps:
627 a few differences. */
629 if (cross_jump
&& simplejump_p (insn
))
631 rtx newjpos
, newlpos
;
636 /* TARGET is nonzero if it is ok to cross jump
637 to code before TARGET. If so, see if matches. */
638 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
641 /* If cannot cross jump to code before the label,
642 see if we can cross jump to another jump to
644 /* Try each other jump to this label. */
645 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
646 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
647 target
!= 0 && newjpos
== 0;
648 target
= jump_chain
[INSN_UID (target
)])
650 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
651 /* Ignore TARGET if it's deleted. */
652 && ! INSN_DELETED_P (target
))
653 find_cross_jump (insn
, target
, 2,
658 do_cross_jump (insn
, newjpos
, newlpos
);
664 /* This code was dead in the previous jump.c! */
665 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
667 /* Return insns all "jump to the same place"
668 so we can cross-jump between any two of them. */
670 rtx newjpos
, newlpos
, target
;
674 /* If cannot cross jump to code before the label,
675 see if we can cross jump to another jump to
677 /* Try each other jump to this label. */
678 for (target
= jump_chain
[0];
679 target
!= 0 && newjpos
== 0;
680 target
= jump_chain
[INSN_UID (target
)])
682 && ! INSN_DELETED_P (target
)
683 && GET_CODE (PATTERN (target
)) == RETURN
)
684 find_cross_jump (insn
, target
, 2,
689 do_cross_jump (insn
, newjpos
, newlpos
);
700 /* Delete extraneous line number notes.
701 Note that two consecutive notes for different lines are not really
702 extraneous. There should be some indication where that line belonged,
703 even if it became empty. */
708 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
709 if (GET_CODE (insn
) == NOTE
)
711 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_BEG
)
712 /* Any previous line note was for the prologue; gdb wants a new
713 note after the prologue even if it is for the same line. */
714 last_note
= NULL_RTX
;
715 else if (NOTE_LINE_NUMBER (insn
) >= 0)
717 /* Delete this note if it is identical to previous note. */
719 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
720 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
737 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
738 notes whose labels don't occur in the insn any more. Returns the
739 largest INSN_UID found. */
747 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
749 if (GET_CODE (insn
) == CODE_LABEL
)
750 LABEL_NUSES (insn
) = (LABEL_PRESERVE_P (insn
) != 0);
751 else if (GET_CODE (insn
) == JUMP_INSN
)
752 JUMP_LABEL (insn
) = 0;
753 else if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == CALL_INSN
)
757 for (note
= REG_NOTES (insn
); note
; note
= next
)
759 next
= XEXP (note
, 1);
760 if (REG_NOTE_KIND (note
) == REG_LABEL
761 && ! reg_mentioned_p (XEXP (note
, 0), PATTERN (insn
)))
762 remove_note (insn
, note
);
765 if (INSN_UID (insn
) > largest_uid
)
766 largest_uid
= INSN_UID (insn
);
772 /* Delete insns following barriers, up to next label.
774 Also delete no-op jumps created by gcse. */
777 delete_barrier_successors (f
)
783 for (insn
= f
; insn
;)
785 if (GET_CODE (insn
) == BARRIER
)
787 insn
= NEXT_INSN (insn
);
789 never_reached_warning (insn
);
791 while (insn
!= 0 && GET_CODE (insn
) != CODE_LABEL
)
793 if (GET_CODE (insn
) == JUMP_INSN
)
795 /* Detect when we're deleting a tablejump; get rid of
796 the jump table as well. */
797 rtx next1
= next_nonnote_insn (insn
);
798 rtx next2
= next1
? next_nonnote_insn (next1
) : 0;
799 if (next2
&& GET_CODE (next1
) == CODE_LABEL
800 && GET_CODE (next2
) == JUMP_INSN
801 && (GET_CODE (PATTERN (next2
)) == ADDR_VEC
802 || GET_CODE (PATTERN (next2
)) == ADDR_DIFF_VEC
))
808 insn
= delete_insn (insn
);
810 else if (GET_CODE (insn
) == NOTE
811 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
812 insn
= NEXT_INSN (insn
);
814 insn
= delete_insn (insn
);
816 /* INSN is now the code_label. */
819 /* Also remove (set (pc) (pc)) insns which can be created by
820 gcse. We eliminate such insns now to avoid having them
821 cause problems later. */
822 else if (GET_CODE (insn
) == JUMP_INSN
823 && (set
= pc_set (insn
)) != NULL
824 && SET_SRC (set
) == pc_rtx
825 && SET_DEST (set
) == pc_rtx
826 && onlyjump_p (insn
))
827 insn
= delete_insn (insn
);
830 insn
= NEXT_INSN (insn
);
834 /* Mark the label each jump jumps to.
835 Combine consecutive labels, and count uses of labels.
837 For each label, make a chain (using `jump_chain')
838 of all the *unconditional* jumps that jump to it;
839 also make a chain of all returns.
841 CROSS_JUMP indicates whether we are doing cross jumping
842 and if we are whether we will be paying attention to
843 death notes or not. */
846 mark_all_labels (f
, cross_jump
)
852 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
855 if (GET_CODE (insn
) == CALL_INSN
856 && GET_CODE (PATTERN (insn
)) == CALL_PLACEHOLDER
)
858 mark_all_labels (XEXP (PATTERN (insn
), 0), cross_jump
);
859 mark_all_labels (XEXP (PATTERN (insn
), 1), cross_jump
);
860 mark_all_labels (XEXP (PATTERN (insn
), 2), cross_jump
);
862 /* Canonicalize the tail recursion label attached to the
863 CALL_PLACEHOLDER insn. */
864 if (XEXP (PATTERN (insn
), 3))
866 rtx label_ref
= gen_rtx_LABEL_REF (VOIDmode
,
867 XEXP (PATTERN (insn
), 3));
868 mark_jump_label (label_ref
, insn
, cross_jump
, 0);
869 XEXP (PATTERN (insn
), 3) = XEXP (label_ref
, 0);
875 mark_jump_label (PATTERN (insn
), insn
, cross_jump
, 0);
876 if (! INSN_DELETED_P (insn
) && GET_CODE (insn
) == JUMP_INSN
)
878 /* When we know the LABEL_REF contained in a REG used in
879 an indirect jump, we'll have a REG_LABEL note so that
880 flow can tell where it's going. */
881 if (JUMP_LABEL (insn
) == 0)
883 rtx label_note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
886 /* But a LABEL_REF around the REG_LABEL note, so
887 that we can canonicalize it. */
888 rtx label_ref
= gen_rtx_LABEL_REF (VOIDmode
,
889 XEXP (label_note
, 0));
891 mark_jump_label (label_ref
, insn
, cross_jump
, 0);
892 XEXP (label_note
, 0) = XEXP (label_ref
, 0);
893 JUMP_LABEL (insn
) = XEXP (label_note
, 0);
896 if (JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
898 jump_chain
[INSN_UID (insn
)]
899 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
900 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
902 if (GET_CODE (PATTERN (insn
)) == RETURN
)
904 jump_chain
[INSN_UID (insn
)] = jump_chain
[0];
905 jump_chain
[0] = insn
;
911 /* Delete all labels already not referenced.
912 Also find and return the last insn. */
915 delete_unreferenced_labels (f
)
918 rtx final
= NULL_RTX
;
921 for (insn
= f
; insn
;)
923 if (GET_CODE (insn
) == CODE_LABEL
924 && LABEL_NUSES (insn
) == 0
925 && LABEL_ALTERNATE_NAME (insn
) == NULL
)
926 insn
= delete_insn (insn
);
930 insn
= NEXT_INSN (insn
);
937 /* Delete various simple forms of moves which have no necessary
941 delete_noop_moves (f
)
946 for (insn
= f
; insn
;)
948 next
= NEXT_INSN (insn
);
950 if (GET_CODE (insn
) == INSN
)
952 register rtx body
= PATTERN (insn
);
954 /* Detect and delete no-op move instructions
955 resulting from not allocating a parameter in a register. */
957 if (GET_CODE (body
) == SET
&& set_noop_p (body
))
958 delete_computation (insn
);
960 /* Detect and ignore no-op move instructions
961 resulting from smart or fortuitous register allocation. */
963 else if (GET_CODE (body
) == SET
)
965 int sreg
= true_regnum (SET_SRC (body
));
966 int dreg
= true_regnum (SET_DEST (body
));
968 if (sreg
== dreg
&& sreg
>= 0)
970 else if (sreg
>= 0 && dreg
>= 0)
973 rtx tem
= find_equiv_reg (NULL_RTX
, insn
, 0,
975 GET_MODE (SET_SRC (body
)));
978 && GET_MODE (tem
) == GET_MODE (SET_DEST (body
)))
980 /* DREG may have been the target of a REG_DEAD note in
981 the insn which makes INSN redundant. If so, reorg
982 would still think it is dead. So search for such a
983 note and delete it if we find it. */
984 if (! find_regno_note (insn
, REG_UNUSED
, dreg
))
985 for (trial
= prev_nonnote_insn (insn
);
986 trial
&& GET_CODE (trial
) != CODE_LABEL
;
987 trial
= prev_nonnote_insn (trial
))
988 if (find_regno_note (trial
, REG_DEAD
, dreg
))
990 remove_death (dreg
, trial
);
994 /* Deleting insn could lose a death-note for SREG. */
995 if ((trial
= find_regno_note (insn
, REG_DEAD
, sreg
)))
997 /* Change this into a USE so that we won't emit
998 code for it, but still can keep the note. */
1000 = gen_rtx_USE (VOIDmode
, XEXP (trial
, 0));
1001 INSN_CODE (insn
) = -1;
1002 /* Remove all reg notes but the REG_DEAD one. */
1003 REG_NOTES (insn
) = trial
;
1004 XEXP (trial
, 1) = NULL_RTX
;
1010 else if (dreg
>= 0 && CONSTANT_P (SET_SRC (body
))
1011 && find_equiv_reg (SET_SRC (body
), insn
, 0, dreg
,
1012 NULL
, 0, GET_MODE (SET_DEST (body
))))
1014 /* This handles the case where we have two consecutive
1015 assignments of the same constant to pseudos that didn't
1016 get a hard reg. Each SET from the constant will be
1017 converted into a SET of the spill register and an
1018 output reload will be made following it. This produces
1019 two loads of the same constant into the same spill
1024 /* Look back for a death note for the first reg.
1025 If there is one, it is no longer accurate. */
1026 while (in_insn
&& GET_CODE (in_insn
) != CODE_LABEL
)
1028 if ((GET_CODE (in_insn
) == INSN
1029 || GET_CODE (in_insn
) == JUMP_INSN
)
1030 && find_regno_note (in_insn
, REG_DEAD
, dreg
))
1032 remove_death (dreg
, in_insn
);
1035 in_insn
= PREV_INSN (in_insn
);
1038 /* Delete the second load of the value. */
1042 else if (GET_CODE (body
) == PARALLEL
)
1044 /* If each part is a set between two identical registers or
1045 a USE or CLOBBER, delete the insn. */
1049 for (i
= XVECLEN (body
, 0) - 1; i
>= 0; i
--)
1051 tem
= XVECEXP (body
, 0, i
);
1052 if (GET_CODE (tem
) == USE
|| GET_CODE (tem
) == CLOBBER
)
1055 if (GET_CODE (tem
) != SET
1056 || (sreg
= true_regnum (SET_SRC (tem
))) < 0
1057 || (dreg
= true_regnum (SET_DEST (tem
))) < 0
1070 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1071 jump. Assume that this unconditional jump is to the exit test code. If
1072 the code is sufficiently simple, make a copy of it before INSN,
1073 followed by a jump to the exit of the loop. Then delete the unconditional
1076 Return 1 if we made the change, else 0.
1078 This is only safe immediately after a regscan pass because it uses the
1079 values of regno_first_uid and regno_last_uid. */
1082 duplicate_loop_exit_test (loop_start
)
1085 rtx insn
, set
, reg
, p
, link
;
1086 rtx copy
= 0, first_copy
= 0;
1088 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
1090 int max_reg
= max_reg_num ();
1093 /* Scan the exit code. We do not perform this optimization if any insn:
1097 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1098 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1099 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1102 We also do not do this if we find an insn with ASM_OPERANDS. While
1103 this restriction should not be necessary, copying an insn with
1104 ASM_OPERANDS can confuse asm_noperands in some cases.
1106 Also, don't do this if the exit code is more than 20 insns. */
1108 for (insn
= exitcode
;
1110 && ! (GET_CODE (insn
) == NOTE
1111 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
1112 insn
= NEXT_INSN (insn
))
1114 switch (GET_CODE (insn
))
1120 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
1121 a jump immediately after the loop start that branches outside
1122 the loop but within an outer loop, near the exit test.
1123 If we copied this exit test and created a phony
1124 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
1125 before the exit test look like these could be safely moved
1126 out of the loop even if they actually may be never executed.
1127 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
1129 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
1130 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
)
1134 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
1135 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
))
1136 /* If we were to duplicate this code, we would not move
1137 the BLOCK notes, and so debugging the moved code would
1138 be difficult. Thus, we only move the code with -O2 or
1145 /* The code below would grossly mishandle REG_WAS_0 notes,
1146 so get rid of them here. */
1147 while ((p
= find_reg_note (insn
, REG_WAS_0
, NULL_RTX
)) != 0)
1148 remove_note (insn
, p
);
1149 if (++num_insns
> 20
1150 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
1151 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
1159 /* Unless INSN is zero, we can do the optimization. */
1165 /* See if any insn sets a register only used in the loop exit code and
1166 not a user variable. If so, replace it with a new register. */
1167 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
1168 if (GET_CODE (insn
) == INSN
1169 && (set
= single_set (insn
)) != 0
1170 && ((reg
= SET_DEST (set
), GET_CODE (reg
) == REG
)
1171 || (GET_CODE (reg
) == SUBREG
1172 && (reg
= SUBREG_REG (reg
), GET_CODE (reg
) == REG
)))
1173 && REGNO (reg
) >= FIRST_PSEUDO_REGISTER
1174 && REGNO_FIRST_UID (REGNO (reg
)) == INSN_UID (insn
))
1176 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
1177 if (REGNO_LAST_UID (REGNO (reg
)) == INSN_UID (p
))
1182 /* We can do the replacement. Allocate reg_map if this is the
1183 first replacement we found. */
1185 reg_map
= (rtx
*) xcalloc (max_reg
, sizeof (rtx
));
1187 REG_LOOP_TEST_P (reg
) = 1;
1189 reg_map
[REGNO (reg
)] = gen_reg_rtx (GET_MODE (reg
));
1193 /* Now copy each insn. */
1194 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
1196 switch (GET_CODE (insn
))
1199 copy
= emit_barrier_before (loop_start
);
1202 /* Only copy line-number notes. */
1203 if (NOTE_LINE_NUMBER (insn
) >= 0)
1205 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
1206 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
1211 copy
= emit_insn_before (copy_insn (PATTERN (insn
)), loop_start
);
1213 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
1215 mark_jump_label (PATTERN (copy
), copy
, 0, 0);
1217 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1219 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
1220 if (REG_NOTE_KIND (link
) != REG_LABEL
)
1222 if (GET_CODE (link
) == EXPR_LIST
)
1224 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link
),
1229 = copy_insn_1 (gen_rtx_INSN_LIST (REG_NOTE_KIND (link
),
1234 if (reg_map
&& REG_NOTES (copy
))
1235 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
1239 copy
= emit_jump_insn_before (copy_insn (PATTERN (insn
)),
1242 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
1243 mark_jump_label (PATTERN (copy
), copy
, 0, 0);
1244 if (REG_NOTES (insn
))
1246 REG_NOTES (copy
) = copy_insn_1 (REG_NOTES (insn
));
1248 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
1251 /* If this is a simple jump, add it to the jump chain. */
1253 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
1254 && simplejump_p (copy
))
1256 jump_chain
[INSN_UID (copy
)]
1257 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
1258 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
1266 /* Record the first insn we copied. We need it so that we can
1267 scan the copied insns for new pseudo registers. */
1272 /* Now clean up by emitting a jump to the end label and deleting the jump
1273 at the start of the loop. */
1274 if (! copy
|| GET_CODE (copy
) != BARRIER
)
1276 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
1279 /* Record the first insn we copied. We need it so that we can
1280 scan the copied insns for new pseudo registers. This may not
1281 be strictly necessary since we should have copied at least one
1282 insn above. But I am going to be safe. */
1286 mark_jump_label (PATTERN (copy
), copy
, 0, 0);
1287 if (INSN_UID (copy
) < max_jump_chain
1288 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
1290 jump_chain
[INSN_UID (copy
)]
1291 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
1292 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
1294 emit_barrier_before (loop_start
);
1297 /* Now scan from the first insn we copied to the last insn we copied
1298 (copy) for new pseudo registers. Do this after the code to jump to
1299 the end label since that might create a new pseudo too. */
1300 reg_scan_update (first_copy
, copy
, max_reg
);
1302 /* Mark the exit code as the virtual top of the converted loop. */
1303 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
1305 delete_insn (next_nonnote_insn (loop_start
));
1314 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
1315 notes between START and END out before START. Assume that END is not
1316 such a note. START may be such a note. Returns the value of the new
1317 starting insn, which may be different if the original start was such a
1321 squeeze_notes (start
, end
)
1327 for (insn
= start
; insn
!= end
; insn
= next
)
1329 next
= NEXT_INSN (insn
);
1330 if (GET_CODE (insn
) == NOTE
1331 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
1332 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
1333 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
1334 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
1335 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
1336 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
1342 rtx prev
= PREV_INSN (insn
);
1343 PREV_INSN (insn
) = PREV_INSN (start
);
1344 NEXT_INSN (insn
) = start
;
1345 NEXT_INSN (PREV_INSN (insn
)) = insn
;
1346 PREV_INSN (NEXT_INSN (insn
)) = insn
;
1347 NEXT_INSN (prev
) = next
;
1348 PREV_INSN (next
) = prev
;
1356 /* Compare the instructions before insn E1 with those before E2
1357 to find an opportunity for cross jumping.
1358 (This means detecting identical sequences of insns followed by
1359 jumps to the same place, or followed by a label and a jump
1360 to that label, and replacing one with a jump to the other.)
1362 Assume E1 is a jump that jumps to label E2
1363 (that is not always true but it might as well be).
1364 Find the longest possible equivalent sequences
1365 and store the first insns of those sequences into *F1 and *F2.
1366 Store zero there if no equivalent preceding instructions are found.
1368 We give up if we find a label in stream 1.
1369 Actually we could transfer that label into stream 2. */
1372 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
1377 register rtx i1
= e1
, i2
= e2
;
1378 register rtx p1
, p2
;
1381 rtx last1
= 0, last2
= 0;
1382 rtx afterlast1
= 0, afterlast2
= 0;
1389 i1
= prev_nonnote_insn (i1
);
1391 i2
= PREV_INSN (i2
);
1392 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
1393 i2
= PREV_INSN (i2
);
1398 /* Don't allow the range of insns preceding E1 or E2
1399 to include the other (E2 or E1). */
1400 if (i2
== e1
|| i1
== e2
)
1403 /* If we will get to this code by jumping, those jumps will be
1404 tensioned to go directly to the new label (before I2),
1405 so this cross-jumping won't cost extra. So reduce the minimum. */
1406 if (GET_CODE (i1
) == CODE_LABEL
)
1412 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
1418 /* If this is a CALL_INSN, compare register usage information.
1419 If we don't check this on stack register machines, the two
1420 CALL_INSNs might be merged leaving reg-stack.c with mismatching
1421 numbers of stack registers in the same basic block.
1422 If we don't check this on machines with delay slots, a delay slot may
1423 be filled that clobbers a parameter expected by the subroutine.
1425 ??? We take the simple route for now and assume that if they're
1426 equal, they were constructed identically. */
1428 if (GET_CODE (i1
) == CALL_INSN
1429 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1
),
1430 CALL_INSN_FUNCTION_USAGE (i2
)))
1434 /* If cross_jump_death_matters is not 0, the insn's mode
1435 indicates whether or not the insn contains any stack-like
1438 if (!lose
&& cross_jump_death_matters
&& stack_regs_mentioned (i1
))
1440 /* If register stack conversion has already been done, then
1441 death notes must also be compared before it is certain that
1442 the two instruction streams match. */
1445 HARD_REG_SET i1_regset
, i2_regset
;
1447 CLEAR_HARD_REG_SET (i1_regset
);
1448 CLEAR_HARD_REG_SET (i2_regset
);
1450 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
1451 if (REG_NOTE_KIND (note
) == REG_DEAD
1452 && STACK_REG_P (XEXP (note
, 0)))
1453 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
1455 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
1456 if (REG_NOTE_KIND (note
) == REG_DEAD
1457 && STACK_REG_P (XEXP (note
, 0)))
1458 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
1460 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
1469 /* Don't allow old-style asm or volatile extended asms to be accepted
1470 for cross jumping purposes. It is conceptually correct to allow
1471 them, since cross-jumping preserves the dynamic instruction order
1472 even though it is changing the static instruction order. However,
1473 if an asm is being used to emit an assembler pseudo-op, such as
1474 the MIPS `.set reorder' pseudo-op, then the static instruction order
1475 matters and it must be preserved. */
1476 if (GET_CODE (p1
) == ASM_INPUT
|| GET_CODE (p2
) == ASM_INPUT
1477 || (GET_CODE (p1
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p1
))
1478 || (GET_CODE (p2
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p2
)))
1481 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
1482 || ! rtx_renumbered_equal_p (p1
, p2
))
1484 /* The following code helps take care of G++ cleanups. */
1488 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
1489 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
1490 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
1491 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
1492 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
1493 /* If the equivalences are not to a constant, they may
1494 reference pseudos that no longer exist, so we can't
1496 && CONSTANT_P (XEXP (equiv1
, 0))
1497 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
1499 rtx s1
= single_set (i1
);
1500 rtx s2
= single_set (i2
);
1501 if (s1
!= 0 && s2
!= 0
1502 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
1504 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
1505 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
1506 if (! rtx_renumbered_equal_p (p1
, p2
))
1508 else if (apply_change_group ())
1513 /* Insns fail to match; cross jumping is limited to the following
1517 /* Don't allow the insn after a compare to be shared by
1518 cross-jumping unless the compare is also shared.
1519 Here, if either of these non-matching insns is a compare,
1520 exclude the following insn from possible cross-jumping. */
1521 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
1522 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
1525 /* If cross-jumping here will feed a jump-around-jump
1526 optimization, this jump won't cost extra, so reduce
1528 if (GET_CODE (i1
) == JUMP_INSN
1530 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
1536 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
1538 /* Ok, this insn is potentially includable in a cross-jump here. */
1539 afterlast1
= last1
, afterlast2
= last2
;
1540 last1
= i1
, last2
= i2
, --minimum
;
1544 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
1545 *f1
= last1
, *f2
= last2
;
1549 do_cross_jump (insn
, newjpos
, newlpos
)
1550 rtx insn
, newjpos
, newlpos
;
1552 /* Find an existing label at this point
1553 or make a new one if there is none. */
1554 register rtx label
= get_label_before (newlpos
);
1556 /* Make the same jump insn jump to the new point. */
1557 if (GET_CODE (PATTERN (insn
)) == RETURN
)
1559 /* Remove from jump chain of returns. */
1560 delete_from_jump_chain (insn
);
1561 /* Change the insn. */
1562 PATTERN (insn
) = gen_jump (label
);
1563 INSN_CODE (insn
) = -1;
1564 JUMP_LABEL (insn
) = label
;
1565 LABEL_NUSES (label
)++;
1566 /* Add to new the jump chain. */
1567 if (INSN_UID (label
) < max_jump_chain
1568 && INSN_UID (insn
) < max_jump_chain
)
1570 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
1571 jump_chain
[INSN_UID (label
)] = insn
;
1575 redirect_jump (insn
, label
, 1);
1577 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
1578 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
1579 the NEWJPOS stream. */
1581 while (newjpos
!= insn
)
1585 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
1586 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
1587 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
1588 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
1589 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
1590 remove_note (newlpos
, lnote
);
1592 delete_insn (newjpos
);
1593 newjpos
= next_real_insn (newjpos
);
1594 newlpos
= next_real_insn (newlpos
);
1598 /* Return the label before INSN, or put a new label there. */
1601 get_label_before (insn
)
1606 /* Find an existing label at this point
1607 or make a new one if there is none. */
1608 label
= prev_nonnote_insn (insn
);
1610 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
1612 rtx prev
= PREV_INSN (insn
);
1614 label
= gen_label_rtx ();
1615 emit_label_after (label
, prev
);
1616 LABEL_NUSES (label
) = 0;
1621 /* Return the label after INSN, or put a new label there. */
1624 get_label_after (insn
)
1629 /* Find an existing label at this point
1630 or make a new one if there is none. */
1631 label
= next_nonnote_insn (insn
);
1633 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
1635 label
= gen_label_rtx ();
1636 emit_label_after (label
, insn
);
1637 LABEL_NUSES (label
) = 0;
1642 /* Return 1 if INSN is a jump that jumps to right after TARGET
1643 only on the condition that TARGET itself would drop through.
1644 Assumes that TARGET is a conditional jump. */
1647 jump_back_p (insn
, target
)
1651 enum rtx_code codei
, codet
;
1654 if (! any_condjump_p (insn
)
1655 || any_uncondjump_p (target
)
1656 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
1658 set
= pc_set (insn
);
1659 tset
= pc_set (target
);
1661 cinsn
= XEXP (SET_SRC (set
), 0);
1662 ctarget
= XEXP (SET_SRC (tset
), 0);
1664 codei
= GET_CODE (cinsn
);
1665 codet
= GET_CODE (ctarget
);
1667 if (XEXP (SET_SRC (set
), 1) == pc_rtx
)
1669 codei
= reversed_comparison_code (cinsn
, insn
);
1670 if (codei
== UNKNOWN
)
1674 if (XEXP (SET_SRC (tset
), 2) == pc_rtx
)
1676 codet
= reversed_comparison_code (ctarget
, target
);
1677 if (codei
== UNKNOWN
)
1681 return (codei
== codet
1682 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
1683 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
1686 /* Given a comparison (CODE ARG0 ARG1), inside a insn, INSN, return an code
1687 of reversed comparison if it is possible to do so. Otherwise return UNKNOWN.
1688 UNKNOWN may be returned in case we are having CC_MODE compare and we don't
1689 know whether it's source is floating point or integer comparison. Machine
1690 description should define REVERSIBLE_CC_MODE and REVERSE_CONDITION macros
1691 to help this function avoid overhead in these cases. */
1693 reversed_comparison_code_parts (code
, arg0
, arg1
, insn
)
1694 rtx insn
, arg0
, arg1
;
1697 enum machine_mode mode
;
1699 /* If this is not actually a comparison, we can't reverse it. */
1700 if (GET_RTX_CLASS (code
) != '<')
1703 mode
= GET_MODE (arg0
);
1704 if (mode
== VOIDmode
)
1705 mode
= GET_MODE (arg1
);
1707 /* First see if machine description supply us way to reverse the comparison.
1708 Give it priority over everything else to allow machine description to do
1710 #ifdef REVERSIBLE_CC_MODE
1711 if (GET_MODE_CLASS (mode
) == MODE_CC
1712 && REVERSIBLE_CC_MODE (mode
))
1714 #ifdef REVERSE_CONDITION
1715 return REVERSE_CONDITION (code
, mode
);
1717 return reverse_condition (code
);
1721 /* Try few special cases based on the comparison code. */
1730 /* It is always safe to reverse EQ and NE, even for the floating
1731 point. Similary the unsigned comparisons are never used for
1732 floating point so we can reverse them in the default way. */
1733 return reverse_condition (code
);
1738 /* In case we already see unordered comparison, we can be sure to
1739 be dealing with floating point so we don't need any more tests. */
1740 return reverse_condition_maybe_unordered (code
);
1745 /* We don't have safe way to reverse these yet. */
1751 /* In case we give up IEEE compatibility, all comparisons are reversible. */
1752 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
1753 || flag_unsafe_math_optimizations
)
1754 return reverse_condition (code
);
1756 if (GET_MODE_CLASS (mode
) == MODE_CC
1763 /* Try to search for the comparison to determine the real mode.
1764 This code is expensive, but with sane machine description it
1765 will be never used, since REVERSIBLE_CC_MODE will return true
1770 for (prev
= prev_nonnote_insn (insn
);
1771 prev
!= 0 && GET_CODE (prev
) != CODE_LABEL
;
1772 prev
= prev_nonnote_insn (prev
))
1774 rtx set
= set_of (arg0
, prev
);
1775 if (set
&& GET_CODE (set
) == SET
1776 && rtx_equal_p (SET_DEST (set
), arg0
))
1778 rtx src
= SET_SRC (set
);
1780 if (GET_CODE (src
) == COMPARE
)
1782 rtx comparison
= src
;
1783 arg0
= XEXP (src
, 0);
1784 mode
= GET_MODE (arg0
);
1785 if (mode
== VOIDmode
)
1786 mode
= GET_MODE (XEXP (comparison
, 1));
1789 /* We can get past reg-reg moves. This may be usefull for model
1790 of i387 comparisons that first move flag registers around. */
1797 /* If register is clobbered in some ununderstandable way,
1804 /* An integer condition. */
1805 if (GET_CODE (arg0
) == CONST_INT
1806 || (GET_MODE (arg0
) != VOIDmode
1807 && GET_MODE_CLASS (mode
) != MODE_CC
1808 && ! FLOAT_MODE_P (mode
)))
1809 return reverse_condition (code
);
1814 /* An wrapper around the previous function to take COMPARISON as rtx
1815 expression. This simplifies many callers. */
1817 reversed_comparison_code (comparison
, insn
)
1818 rtx comparison
, insn
;
1820 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
1822 return reversed_comparison_code_parts (GET_CODE (comparison
),
1823 XEXP (comparison
, 0),
1824 XEXP (comparison
, 1), insn
);
1827 /* Given an rtx-code for a comparison, return the code for the negated
1828 comparison. If no such code exists, return UNKNOWN.
1830 WATCH OUT! reverse_condition is not safe to use on a jump that might
1831 be acting on the results of an IEEE floating point comparison, because
1832 of the special treatment of non-signaling nans in comparisons.
1833 Use reversed_comparison_code instead. */
1836 reverse_condition (code
)
1879 /* Similar, but we're allowed to generate unordered comparisons, which
1880 makes it safe for IEEE floating-point. Of course, we have to recognize
1881 that the target will support them too... */
1884 reverse_condition_maybe_unordered (code
)
1887 /* Non-IEEE formats don't have unordered conditions. */
1888 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
)
1889 return reverse_condition (code
);
1927 /* Similar, but return the code when two operands of a comparison are swapped.
1928 This IS safe for IEEE floating-point. */
1931 swap_condition (code
)
1974 /* Given a comparison CODE, return the corresponding unsigned comparison.
1975 If CODE is an equality comparison or already an unsigned comparison,
1976 CODE is returned. */
1979 unsigned_condition (code
)
2006 /* Similarly, return the signed version of a comparison. */
2009 signed_condition (code
)
2036 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2037 truth of CODE1 implies the truth of CODE2. */
2040 comparison_dominates_p (code1
, code2
)
2041 enum rtx_code code1
, code2
;
2043 /* UNKNOWN comparison codes can happen as a result of trying to revert
2045 They can't match anything, so we have to reject them here. */
2046 if (code1
== UNKNOWN
|| code2
== UNKNOWN
)
2055 if (code2
== UNLE
|| code2
== UNGE
)
2060 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
2061 || code2
== ORDERED
)
2066 if (code2
== UNLE
|| code2
== NE
)
2071 if (code2
== LE
|| code2
== NE
|| code2
== ORDERED
|| code2
== LTGT
)
2076 if (code2
== UNGE
|| code2
== NE
)
2081 if (code2
== GE
|| code2
== NE
|| code2
== ORDERED
|| code2
== LTGT
)
2087 if (code2
== ORDERED
)
2092 if (code2
== NE
|| code2
== ORDERED
)
2097 if (code2
== LEU
|| code2
== NE
)
2102 if (code2
== GEU
|| code2
== NE
)
2107 if (code2
== NE
|| code2
== UNEQ
|| code2
== UNLE
|| code2
== UNLT
2108 || code2
== UNGE
|| code2
== UNGT
)
2119 /* Return 1 if INSN is an unconditional jump and nothing else. */
2125 return (GET_CODE (insn
) == JUMP_INSN
2126 && GET_CODE (PATTERN (insn
)) == SET
2127 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
2128 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
2131 /* Return nonzero if INSN is a (possibly) conditional jump
2134 Use this function is deprecated, since we need to support combined
2135 branch and compare insns. Use any_condjump_p instead whenever possible. */
2141 register rtx x
= PATTERN (insn
);
2143 if (GET_CODE (x
) != SET
2144 || GET_CODE (SET_DEST (x
)) != PC
)
2148 if (GET_CODE (x
) == LABEL_REF
)
2151 return (GET_CODE (x
) == IF_THEN_ELSE
2152 && ((GET_CODE (XEXP (x
, 2)) == PC
2153 && (GET_CODE (XEXP (x
, 1)) == LABEL_REF
2154 || GET_CODE (XEXP (x
, 1)) == RETURN
))
2155 || (GET_CODE (XEXP (x
, 1)) == PC
2156 && (GET_CODE (XEXP (x
, 2)) == LABEL_REF
2157 || GET_CODE (XEXP (x
, 2)) == RETURN
))));
2162 /* Return nonzero if INSN is a (possibly) conditional jump inside a
2165 Use this function is deprecated, since we need to support combined
2166 branch and compare insns. Use any_condjump_p instead whenever possible. */
2169 condjump_in_parallel_p (insn
)
2172 register rtx x
= PATTERN (insn
);
2174 if (GET_CODE (x
) != PARALLEL
)
2177 x
= XVECEXP (x
, 0, 0);
2179 if (GET_CODE (x
) != SET
)
2181 if (GET_CODE (SET_DEST (x
)) != PC
)
2183 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2185 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2187 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2188 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2189 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2191 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2192 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2193 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2198 /* Return set of PC, otherwise NULL. */
2205 if (GET_CODE (insn
) != JUMP_INSN
)
2207 pat
= PATTERN (insn
);
2209 /* The set is allowed to appear either as the insn pattern or
2210 the first set in a PARALLEL. */
2211 if (GET_CODE (pat
) == PARALLEL
)
2212 pat
= XVECEXP (pat
, 0, 0);
2213 if (GET_CODE (pat
) == SET
&& GET_CODE (SET_DEST (pat
)) == PC
)
2219 /* Return true when insn is an unconditional direct jump,
2220 possibly bundled inside a PARALLEL. */
2223 any_uncondjump_p (insn
)
2226 rtx x
= pc_set (insn
);
2229 if (GET_CODE (SET_SRC (x
)) != LABEL_REF
)
2234 /* Return true when insn is a conditional jump. This function works for
2235 instructions containing PC sets in PARALLELs. The instruction may have
2236 various other effects so before removing the jump you must verify
2239 Note that unlike condjump_p it returns false for unconditional jumps. */
2242 any_condjump_p (insn
)
2245 rtx x
= pc_set (insn
);
2250 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2253 a
= GET_CODE (XEXP (SET_SRC (x
), 1));
2254 b
= GET_CODE (XEXP (SET_SRC (x
), 2));
2256 return ((b
== PC
&& (a
== LABEL_REF
|| a
== RETURN
))
2257 || (a
== PC
&& (b
== LABEL_REF
|| b
== RETURN
)));
2260 /* Return the label of a conditional jump. */
2263 condjump_label (insn
)
2266 rtx x
= pc_set (insn
);
2271 if (GET_CODE (x
) == LABEL_REF
)
2273 if (GET_CODE (x
) != IF_THEN_ELSE
)
2275 if (XEXP (x
, 2) == pc_rtx
&& GET_CODE (XEXP (x
, 1)) == LABEL_REF
)
2277 if (XEXP (x
, 1) == pc_rtx
&& GET_CODE (XEXP (x
, 2)) == LABEL_REF
)
2282 /* Return true if INSN is a (possibly conditional) return insn. */
2285 returnjump_p_1 (loc
, data
)
2287 void *data ATTRIBUTE_UNUSED
;
2290 return x
&& GET_CODE (x
) == RETURN
;
2297 if (GET_CODE (insn
) != JUMP_INSN
)
2299 return for_each_rtx (&PATTERN (insn
), returnjump_p_1
, NULL
);
2302 /* Return true if INSN is a jump that only transfers control and
2311 if (GET_CODE (insn
) != JUMP_INSN
)
2314 set
= single_set (insn
);
2317 if (GET_CODE (SET_DEST (set
)) != PC
)
2319 if (side_effects_p (SET_SRC (set
)))
2327 /* Return 1 if X is an RTX that does nothing but set the condition codes
2328 and CLOBBER or USE registers.
2329 Return -1 if X does explicitly set the condition codes,
2330 but also does other things. */
2334 rtx x ATTRIBUTE_UNUSED
;
2336 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
2338 if (GET_CODE (x
) == PARALLEL
)
2342 int other_things
= 0;
2343 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2345 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
2346 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
2348 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
2351 return ! sets_cc0
? 0 : other_things
? -1 : 1;
2357 /* Follow any unconditional jump at LABEL;
2358 return the ultimate label reached by any such chain of jumps.
2359 If LABEL is not followed by a jump, return LABEL.
2360 If the chain loops or we can't find end, return LABEL,
2361 since that tells caller to avoid changing the insn.
2363 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2364 a USE or CLOBBER. */
2367 follow_jumps (label
)
2372 register rtx value
= label
;
2377 && (insn
= next_active_insn (value
)) != 0
2378 && GET_CODE (insn
) == JUMP_INSN
2379 && ((JUMP_LABEL (insn
) != 0 && any_uncondjump_p (insn
)
2380 && onlyjump_p (insn
))
2381 || GET_CODE (PATTERN (insn
)) == RETURN
)
2382 && (next
= NEXT_INSN (insn
))
2383 && GET_CODE (next
) == BARRIER
);
2386 /* Don't chain through the insn that jumps into a loop
2387 from outside the loop,
2388 since that would create multiple loop entry jumps
2389 and prevent loop optimization. */
2391 if (!reload_completed
)
2392 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
2393 if (GET_CODE (tem
) == NOTE
2394 && (NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
2395 /* ??? Optional. Disables some optimizations, but makes
2396 gcov output more accurate with -O. */
2397 || (flag_test_coverage
&& NOTE_LINE_NUMBER (tem
) > 0)))
2400 /* If we have found a cycle, make the insn jump to itself. */
2401 if (JUMP_LABEL (insn
) == label
)
2404 tem
= next_active_insn (JUMP_LABEL (insn
));
2405 if (tem
&& (GET_CODE (PATTERN (tem
)) == ADDR_VEC
2406 || GET_CODE (PATTERN (tem
)) == ADDR_DIFF_VEC
))
2409 value
= JUMP_LABEL (insn
);
2416 /* Assuming that field IDX of X is a vector of label_refs,
2417 replace each of them by the ultimate label reached by it.
2418 Return nonzero if a change is made.
2419 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2422 tension_vector_labels (x
, idx
)
2428 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
2430 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
2431 register rtx nlabel
= follow_jumps (olabel
);
2432 if (nlabel
&& nlabel
!= olabel
)
2434 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
2435 ++LABEL_NUSES (nlabel
);
2436 if (--LABEL_NUSES (olabel
) == 0)
2437 delete_insn (olabel
);
2444 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2445 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2446 in INSN, then store one of them in JUMP_LABEL (INSN).
2447 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2448 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2449 Also, when there are consecutive labels, canonicalize on the last of them.
2451 Note that two labels separated by a loop-beginning note
2452 must be kept distinct if we have not yet done loop-optimization,
2453 because the gap between them is where loop-optimize
2454 will want to move invariant code to. CROSS_JUMP tells us
2455 that loop-optimization is done with.
2457 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2458 two labels distinct if they are separated by only USE or CLOBBER insns. */
2461 mark_jump_label (x
, insn
, cross_jump
, in_mem
)
2467 register RTX_CODE code
= GET_CODE (x
);
2469 register const char *fmt
;
2491 /* If this is a constant-pool reference, see if it is a label. */
2492 if (CONSTANT_POOL_ADDRESS_P (x
))
2493 mark_jump_label (get_pool_constant (x
), insn
, cross_jump
, in_mem
);
2498 rtx label
= XEXP (x
, 0);
2502 /* Ignore remaining references to unreachable labels that
2503 have been deleted. */
2504 if (GET_CODE (label
) == NOTE
2505 && NOTE_LINE_NUMBER (label
) == NOTE_INSN_DELETED_LABEL
)
2508 if (GET_CODE (label
) != CODE_LABEL
)
2511 /* Ignore references to labels of containing functions. */
2512 if (LABEL_REF_NONLOCAL_P (x
))
2515 /* If there are other labels following this one,
2516 replace it with the last of the consecutive labels. */
2517 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
2519 if (GET_CODE (next
) == CODE_LABEL
)
2521 else if (cross_jump
&& GET_CODE (next
) == INSN
2522 && (GET_CODE (PATTERN (next
)) == USE
2523 || GET_CODE (PATTERN (next
)) == CLOBBER
))
2525 else if (GET_CODE (next
) != NOTE
)
2527 else if (! cross_jump
2528 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
2529 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
2530 /* ??? Optional. Disables some optimizations, but
2531 makes gcov output more accurate with -O. */
2532 || (flag_test_coverage
2533 && NOTE_LINE_NUMBER (next
) > 0)))
2537 XEXP (x
, 0) = label
;
2538 if (! insn
|| ! INSN_DELETED_P (insn
))
2539 ++LABEL_NUSES (label
);
2543 if (GET_CODE (insn
) == JUMP_INSN
)
2544 JUMP_LABEL (insn
) = label
;
2547 /* If we've changed the label, update notes accordingly. */
2548 if (label
!= olabel
)
2552 /* We may have a REG_LABEL note to indicate that this
2553 instruction uses the label. */
2554 note
= find_reg_note (insn
, REG_LABEL
, olabel
);
2556 XEXP (note
, 0) = label
;
2558 /* We may also have a REG_EQUAL note to indicate that
2559 a register is being set to the address of the
2561 note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
2563 && GET_CODE (XEXP (note
, 0)) == LABEL_REF
2564 && XEXP (XEXP (note
, 0), 0) == olabel
)
2565 XEXP (XEXP (note
, 0), 0) = label
;
2568 /* Add a REG_LABEL note for LABEL unless there already
2569 is one. All uses of a label, except for labels
2570 that are the targets of jumps, must have a
2572 if (! find_reg_note (insn
, REG_LABEL
, label
))
2573 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, label
,
2580 /* Do walk the labels in a vector, but not the first operand of an
2581 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2584 if (! INSN_DELETED_P (insn
))
2586 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
2588 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
2589 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
,
2590 cross_jump
, in_mem
);
2598 fmt
= GET_RTX_FORMAT (code
);
2599 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2602 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
, in_mem
);
2603 else if (fmt
[i
] == 'E')
2606 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2607 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
, in_mem
);
2612 /* If all INSN does is set the pc, delete it,
2613 and delete the insn that set the condition codes for it
2614 if that's what the previous thing was. */
2620 register rtx set
= single_set (insn
);
2622 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
2623 delete_computation (insn
);
2626 /* Verify INSN is a BARRIER and delete it. */
2629 delete_barrier (insn
)
2632 if (GET_CODE (insn
) != BARRIER
)
2638 /* Recursively delete prior insns that compute the value (used only by INSN
2639 which the caller is deleting) stored in the register mentioned by NOTE
2640 which is a REG_DEAD note associated with INSN. */
2643 delete_prior_computation (note
, insn
)
2648 rtx reg
= XEXP (note
, 0);
2650 for (our_prev
= prev_nonnote_insn (insn
);
2651 our_prev
&& (GET_CODE (our_prev
) == INSN
2652 || GET_CODE (our_prev
) == CALL_INSN
);
2653 our_prev
= prev_nonnote_insn (our_prev
))
2655 rtx pat
= PATTERN (our_prev
);
2657 /* If we reach a CALL which is not calling a const function
2658 or the callee pops the arguments, then give up. */
2659 if (GET_CODE (our_prev
) == CALL_INSN
2660 && (! CONST_CALL_P (our_prev
)
2661 || GET_CODE (pat
) != SET
|| GET_CODE (SET_SRC (pat
)) != CALL
))
2664 /* If we reach a SEQUENCE, it is too complex to try to
2665 do anything with it, so give up. */
2666 if (GET_CODE (pat
) == SEQUENCE
)
2669 if (GET_CODE (pat
) == USE
2670 && GET_CODE (XEXP (pat
, 0)) == INSN
)
2671 /* reorg creates USEs that look like this. We leave them
2672 alone because reorg needs them for its own purposes. */
2675 if (reg_set_p (reg
, pat
))
2677 if (side_effects_p (pat
) && GET_CODE (our_prev
) != CALL_INSN
)
2680 if (GET_CODE (pat
) == PARALLEL
)
2682 /* If we find a SET of something else, we can't
2687 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2689 rtx part
= XVECEXP (pat
, 0, i
);
2691 if (GET_CODE (part
) == SET
2692 && SET_DEST (part
) != reg
)
2696 if (i
== XVECLEN (pat
, 0))
2697 delete_computation (our_prev
);
2699 else if (GET_CODE (pat
) == SET
2700 && GET_CODE (SET_DEST (pat
)) == REG
)
2702 int dest_regno
= REGNO (SET_DEST (pat
));
2705 + (dest_regno
< FIRST_PSEUDO_REGISTER
2706 ? HARD_REGNO_NREGS (dest_regno
,
2707 GET_MODE (SET_DEST (pat
))) : 1));
2708 int regno
= REGNO (reg
);
2711 + (regno
< FIRST_PSEUDO_REGISTER
2712 ? HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) : 1));
2714 if (dest_regno
>= regno
2715 && dest_endregno
<= endregno
)
2716 delete_computation (our_prev
);
2718 /* We may have a multi-word hard register and some, but not
2719 all, of the words of the register are needed in subsequent
2720 insns. Write REG_UNUSED notes for those parts that were not
2722 else if (dest_regno
<= regno
2723 && dest_endregno
>= endregno
)
2727 REG_NOTES (our_prev
)
2728 = gen_rtx_EXPR_LIST (REG_UNUSED
, reg
,
2729 REG_NOTES (our_prev
));
2731 for (i
= dest_regno
; i
< dest_endregno
; i
++)
2732 if (! find_regno_note (our_prev
, REG_UNUSED
, i
))
2735 if (i
== dest_endregno
)
2736 delete_computation (our_prev
);
2743 /* If PAT references the register that dies here, it is an
2744 additional use. Hence any prior SET isn't dead. However, this
2745 insn becomes the new place for the REG_DEAD note. */
2746 if (reg_overlap_mentioned_p (reg
, pat
))
2748 XEXP (note
, 1) = REG_NOTES (our_prev
);
2749 REG_NOTES (our_prev
) = note
;
2755 /* Delete INSN and recursively delete insns that compute values used only
2756 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2757 If we are running before flow.c, we need do nothing since flow.c will
2758 delete dead code. We also can't know if the registers being used are
2759 dead or not at this point.
2761 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2762 nothing other than set a register that dies in this insn, we can delete
2765 On machines with CC0, if CC0 is used in this insn, we may be able to
2766 delete the insn that set it. */
2769 delete_computation (insn
)
2775 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
2777 rtx prev
= prev_nonnote_insn (insn
);
2778 /* We assume that at this stage
2779 CC's are always set explicitly
2780 and always immediately before the jump that
2781 will use them. So if the previous insn
2782 exists to set the CC's, delete it
2783 (unless it performs auto-increments, etc.). */
2784 if (prev
&& GET_CODE (prev
) == INSN
2785 && sets_cc0_p (PATTERN (prev
)))
2787 if (sets_cc0_p (PATTERN (prev
)) > 0
2788 && ! side_effects_p (PATTERN (prev
)))
2789 delete_computation (prev
);
2791 /* Otherwise, show that cc0 won't be used. */
2792 REG_NOTES (prev
) = gen_rtx_EXPR_LIST (REG_UNUSED
,
2793 cc0_rtx
, REG_NOTES (prev
));
2798 for (note
= REG_NOTES (insn
); note
; note
= next
)
2800 next
= XEXP (note
, 1);
2802 if (REG_NOTE_KIND (note
) != REG_DEAD
2803 /* Verify that the REG_NOTE is legitimate. */
2804 || GET_CODE (XEXP (note
, 0)) != REG
)
2807 delete_prior_computation (note
, insn
);
2813 /* Delete insn INSN from the chain of insns and update label ref counts.
2814 May delete some following insns as a consequence; may even delete
2815 a label elsewhere and insns that follow it.
2817 Returns the first insn after INSN that was not deleted. */
2823 register rtx next
= NEXT_INSN (insn
);
2824 register rtx prev
= PREV_INSN (insn
);
2825 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
2826 register int dont_really_delete
= 0;
2829 while (next
&& INSN_DELETED_P (next
))
2830 next
= NEXT_INSN (next
);
2832 /* This insn is already deleted => return first following nondeleted. */
2833 if (INSN_DELETED_P (insn
))
2837 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
2839 /* Don't delete user-declared labels. When optimizing, convert them
2840 to special NOTEs instead. When not optimizing, leave them alone. */
2841 if (was_code_label
&& LABEL_NAME (insn
) != 0)
2845 const char *name
= LABEL_NAME (insn
);
2846 PUT_CODE (insn
, NOTE
);
2847 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
2848 NOTE_SOURCE_FILE (insn
) = name
;
2851 dont_really_delete
= 1;
2854 /* Mark this insn as deleted. */
2855 INSN_DELETED_P (insn
) = 1;
2857 /* If this is an unconditional jump, delete it from the jump chain. */
2858 if (simplejump_p (insn
))
2859 delete_from_jump_chain (insn
);
2861 /* If instruction is followed by a barrier,
2862 delete the barrier too. */
2864 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
2866 INSN_DELETED_P (next
) = 1;
2867 next
= NEXT_INSN (next
);
2870 /* Patch out INSN (and the barrier if any) */
2872 if (! dont_really_delete
)
2876 NEXT_INSN (prev
) = next
;
2877 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
2878 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
2879 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
2884 PREV_INSN (next
) = prev
;
2885 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
2886 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
2889 if (prev
&& NEXT_INSN (prev
) == 0)
2890 set_last_insn (prev
);
2893 /* If deleting a jump, decrement the count of the label,
2894 and delete the label if it is now unused. */
2896 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
2898 rtx lab
= JUMP_LABEL (insn
), lab_next
;
2900 if (--LABEL_NUSES (lab
) == 0)
2902 /* This can delete NEXT or PREV,
2903 either directly if NEXT is JUMP_LABEL (INSN),
2904 or indirectly through more levels of jumps. */
2907 /* I feel a little doubtful about this loop,
2908 but I see no clean and sure alternative way
2909 to find the first insn after INSN that is not now deleted.
2910 I hope this works. */
2911 while (next
&& INSN_DELETED_P (next
))
2912 next
= NEXT_INSN (next
);
2915 else if ((lab_next
= next_nonnote_insn (lab
)) != NULL
2916 && GET_CODE (lab_next
) == JUMP_INSN
2917 && (GET_CODE (PATTERN (lab_next
)) == ADDR_VEC
2918 || GET_CODE (PATTERN (lab_next
)) == ADDR_DIFF_VEC
))
2920 /* If we're deleting the tablejump, delete the dispatch table.
2921 We may not be able to kill the label immediately preceeding
2922 just yet, as it might be referenced in code leading up to
2924 delete_insn (lab_next
);
2928 /* Likewise if we're deleting a dispatch table. */
2930 if (GET_CODE (insn
) == JUMP_INSN
2931 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
2932 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
2934 rtx pat
= PATTERN (insn
);
2935 int i
, diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2936 int len
= XVECLEN (pat
, diff_vec_p
);
2938 for (i
= 0; i
< len
; i
++)
2939 if (--LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)) == 0)
2940 delete_insn (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0));
2941 while (next
&& INSN_DELETED_P (next
))
2942 next
= NEXT_INSN (next
);
2946 /* Likewise for an ordinary INSN / CALL_INSN with a REG_LABEL note. */
2947 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == CALL_INSN
)
2948 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
2949 if (REG_NOTE_KIND (note
) == REG_LABEL
2950 /* This could also be a NOTE_INSN_DELETED_LABEL note. */
2951 && GET_CODE (XEXP (note
, 0)) == CODE_LABEL
)
2952 if (--LABEL_NUSES (XEXP (note
, 0)) == 0)
2953 delete_insn (XEXP (note
, 0));
2955 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
2956 prev
= PREV_INSN (prev
);
2958 /* If INSN was a label and a dispatch table follows it,
2959 delete the dispatch table. The tablejump must have gone already.
2960 It isn't useful to fall through into a table. */
2963 && NEXT_INSN (insn
) != 0
2964 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
2965 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
2966 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
2967 next
= delete_insn (NEXT_INSN (insn
));
2969 /* If INSN was a label, delete insns following it if now unreachable. */
2971 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
2973 register RTX_CODE code
;
2975 && (GET_RTX_CLASS (code
= GET_CODE (next
)) == 'i'
2976 || code
== NOTE
|| code
== BARRIER
2977 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
2980 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
2981 next
= NEXT_INSN (next
);
2982 /* Keep going past other deleted labels to delete what follows. */
2983 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
2984 next
= NEXT_INSN (next
);
2986 /* Note: if this deletes a jump, it can cause more
2987 deletion of unreachable code, after a different label.
2988 As long as the value from this recursive call is correct,
2989 this invocation functions correctly. */
2990 next
= delete_insn (next
);
2997 /* Advance from INSN till reaching something not deleted
2998 then return that. May return INSN itself. */
3001 next_nondeleted_insn (insn
)
3004 while (INSN_DELETED_P (insn
))
3005 insn
= NEXT_INSN (insn
);
3009 /* Delete a range of insns from FROM to TO, inclusive.
3010 This is for the sake of peephole optimization, so assume
3011 that whatever these insns do will still be done by a new
3012 peephole insn that will replace them. */
3015 delete_for_peephole (from
, to
)
3016 register rtx from
, to
;
3018 register rtx insn
= from
;
3022 register rtx next
= NEXT_INSN (insn
);
3023 register rtx prev
= PREV_INSN (insn
);
3025 if (GET_CODE (insn
) != NOTE
)
3027 INSN_DELETED_P (insn
) = 1;
3029 /* Patch this insn out of the chain. */
3030 /* We don't do this all at once, because we
3031 must preserve all NOTEs. */
3033 NEXT_INSN (prev
) = next
;
3036 PREV_INSN (next
) = prev
;
3044 /* Note that if TO is an unconditional jump
3045 we *do not* delete the BARRIER that follows,
3046 since the peephole that replaces this sequence
3047 is also an unconditional jump in that case. */
3050 /* We have determined that INSN is never reached, and are about to
3051 delete it. Print a warning if the user asked for one.
3053 To try to make this warning more useful, this should only be called
3054 once per basic block not reached, and it only warns when the basic
3055 block contains more than one line from the current function, and
3056 contains at least one operation. CSE and inlining can duplicate insns,
3057 so it's possible to get spurious warnings from this. */
3060 never_reached_warning (avoided_insn
)
3064 rtx a_line_note
= NULL
;
3065 int two_avoided_lines
= 0;
3066 int contains_insn
= 0;
3068 if (! warn_notreached
)
3071 /* Scan forwards, looking at LINE_NUMBER notes, until
3072 we hit a LABEL or we run out of insns. */
3074 for (insn
= avoided_insn
; insn
!= NULL
; insn
= NEXT_INSN (insn
))
3076 if (GET_CODE (insn
) == CODE_LABEL
)
3078 else if (GET_CODE (insn
) == NOTE
/* A line number note? */
3079 && NOTE_LINE_NUMBER (insn
) >= 0)
3081 if (a_line_note
== NULL
)
3084 two_avoided_lines
|= (NOTE_LINE_NUMBER (a_line_note
)
3085 != NOTE_LINE_NUMBER (insn
));
3087 else if (INSN_P (insn
))
3090 if (two_avoided_lines
&& contains_insn
)
3091 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note
),
3092 NOTE_LINE_NUMBER (a_line_note
),
3093 "will never be executed");
3096 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
3097 NLABEL as a return. Accrue modifications into the change group. */
3100 redirect_exp_1 (loc
, olabel
, nlabel
, insn
)
3105 register rtx x
= *loc
;
3106 register RTX_CODE code
= GET_CODE (x
);
3108 register const char *fmt
;
3110 if (code
== LABEL_REF
)
3112 if (XEXP (x
, 0) == olabel
)
3116 n
= gen_rtx_LABEL_REF (VOIDmode
, nlabel
);
3118 n
= gen_rtx_RETURN (VOIDmode
);
3120 validate_change (insn
, loc
, n
, 1);
3124 else if (code
== RETURN
&& olabel
== 0)
3126 x
= gen_rtx_LABEL_REF (VOIDmode
, nlabel
);
3127 if (loc
== &PATTERN (insn
))
3128 x
= gen_rtx_SET (VOIDmode
, pc_rtx
, x
);
3129 validate_change (insn
, loc
, x
, 1);
3133 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
3134 && GET_CODE (SET_SRC (x
)) == LABEL_REF
3135 && XEXP (SET_SRC (x
), 0) == olabel
)
3137 validate_change (insn
, loc
, gen_rtx_RETURN (VOIDmode
), 1);
3141 fmt
= GET_RTX_FORMAT (code
);
3142 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3145 redirect_exp_1 (&XEXP (x
, i
), olabel
, nlabel
, insn
);
3146 else if (fmt
[i
] == 'E')
3149 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3150 redirect_exp_1 (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
);
3155 /* Similar, but apply the change group and report success or failure. */
3158 redirect_exp (olabel
, nlabel
, insn
)
3164 if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
3165 loc
= &XVECEXP (PATTERN (insn
), 0, 0);
3167 loc
= &PATTERN (insn
);
3169 redirect_exp_1 (loc
, olabel
, nlabel
, insn
);
3170 if (num_validated_changes () == 0)
3173 return apply_change_group ();
3176 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
3177 the modifications into the change group. Return false if we did
3178 not see how to do that. */
3181 redirect_jump_1 (jump
, nlabel
)
3184 int ochanges
= num_validated_changes ();
3187 if (GET_CODE (PATTERN (jump
)) == PARALLEL
)
3188 loc
= &XVECEXP (PATTERN (jump
), 0, 0);
3190 loc
= &PATTERN (jump
);
3192 redirect_exp_1 (loc
, JUMP_LABEL (jump
), nlabel
, jump
);
3193 return num_validated_changes () > ochanges
;
3196 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
3197 jump target label is unused as a result, it and the code following
3200 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3203 The return value will be 1 if the change was made, 0 if it wasn't
3204 (this can only occur for NLABEL == 0). */
3207 redirect_jump (jump
, nlabel
, delete_unused
)
3211 register rtx olabel
= JUMP_LABEL (jump
);
3213 if (nlabel
== olabel
)
3216 if (! redirect_exp (olabel
, nlabel
, jump
))
3219 /* If this is an unconditional branch, delete it from the jump_chain of
3220 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3221 have UID's in range and JUMP_CHAIN is valid). */
3222 if (jump_chain
&& (simplejump_p (jump
)
3223 || GET_CODE (PATTERN (jump
)) == RETURN
))
3225 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
3227 delete_from_jump_chain (jump
);
3228 if (label_index
< max_jump_chain
3229 && INSN_UID (jump
) < max_jump_chain
)
3231 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
3232 jump_chain
[label_index
] = jump
;
3236 JUMP_LABEL (jump
) = nlabel
;
3238 ++LABEL_NUSES (nlabel
);
3240 /* If we're eliding the jump over exception cleanups at the end of a
3241 function, move the function end note so that -Wreturn-type works. */
3242 if (olabel
&& nlabel
3243 && NEXT_INSN (olabel
)
3244 && GET_CODE (NEXT_INSN (olabel
)) == NOTE
3245 && NOTE_LINE_NUMBER (NEXT_INSN (olabel
)) == NOTE_INSN_FUNCTION_END
)
3246 emit_note_after (NOTE_INSN_FUNCTION_END
, nlabel
);
3248 if (olabel
&& --LABEL_NUSES (olabel
) == 0 && delete_unused
)
3249 delete_insn (olabel
);
3254 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3255 Accrue the modifications into the change group. */
3261 register RTX_CODE code
;
3262 rtx x
= pc_set (insn
);
3268 code
= GET_CODE (x
);
3270 if (code
== IF_THEN_ELSE
)
3272 register rtx comp
= XEXP (x
, 0);
3274 enum rtx_code reversed_code
;
3276 /* We can do this in two ways: The preferable way, which can only
3277 be done if this is not an integer comparison, is to reverse
3278 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3279 of the IF_THEN_ELSE. If we can't do either, fail. */
3281 reversed_code
= reversed_comparison_code (comp
, insn
);
3283 if (reversed_code
!= UNKNOWN
)
3285 validate_change (insn
, &XEXP (x
, 0),
3286 gen_rtx_fmt_ee (reversed_code
,
3287 GET_MODE (comp
), XEXP (comp
, 0),
3294 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
3295 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
3301 /* Invert the jump condition of conditional jump insn, INSN.
3303 Return 1 if we can do so, 0 if we cannot find a way to do so that
3304 matches a pattern. */
3310 invert_exp_1 (insn
);
3311 if (num_validated_changes () == 0)
3314 return apply_change_group ();
3317 /* Invert the condition of the jump JUMP, and make it jump to label
3318 NLABEL instead of where it jumps now. Accrue changes into the
3319 change group. Return false if we didn't see how to perform the
3320 inversion and redirection. */
3323 invert_jump_1 (jump
, nlabel
)
3328 ochanges
= num_validated_changes ();
3329 invert_exp_1 (jump
);
3330 if (num_validated_changes () == ochanges
)
3333 return redirect_jump_1 (jump
, nlabel
);
3336 /* Invert the condition of the jump JUMP, and make it jump to label
3337 NLABEL instead of where it jumps now. Return true if successful. */
3340 invert_jump (jump
, nlabel
, delete_unused
)
3344 /* We have to either invert the condition and change the label or
3345 do neither. Either operation could fail. We first try to invert
3346 the jump. If that succeeds, we try changing the label. If that fails,
3347 we invert the jump back to what it was. */
3349 if (! invert_exp (jump
))
3352 if (redirect_jump (jump
, nlabel
, delete_unused
))
3354 /* An inverted jump means that a probability taken becomes a
3355 probability not taken. Subtract the branch probability from the
3356 probability base to convert it back to a taken probability. */
3358 rtx note
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3360 XEXP (note
, 0) = GEN_INT (REG_BR_PROB_BASE
- INTVAL (XEXP (note
, 0)));
3365 if (! invert_exp (jump
))
3366 /* This should just be putting it back the way it was. */
3372 /* Delete the instruction JUMP from any jump chain it might be on. */
3375 delete_from_jump_chain (jump
)
3379 rtx olabel
= JUMP_LABEL (jump
);
3381 /* Handle unconditional jumps. */
3382 if (jump_chain
&& olabel
!= 0
3383 && INSN_UID (olabel
) < max_jump_chain
3384 && simplejump_p (jump
))
3385 index
= INSN_UID (olabel
);
3386 /* Handle return insns. */
3387 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
3392 if (jump_chain
[index
] == jump
)
3393 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
3398 for (insn
= jump_chain
[index
];
3400 insn
= jump_chain
[INSN_UID (insn
)])
3401 if (jump_chain
[INSN_UID (insn
)] == jump
)
3403 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
3409 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3411 If the old jump target label (before the dispatch table) becomes unused,
3412 it and the dispatch table may be deleted. In that case, find the insn
3413 before the jump references that label and delete it and logical successors
3417 redirect_tablejump (jump
, nlabel
)
3420 register rtx olabel
= JUMP_LABEL (jump
);
3421 rtx
*notep
, note
, next
;
3423 /* Add this jump to the jump_chain of NLABEL. */
3424 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
3425 && INSN_UID (jump
) < max_jump_chain
)
3427 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
3428 jump_chain
[INSN_UID (nlabel
)] = jump
;
3431 for (notep
= ®_NOTES (jump
), note
= *notep
; note
; note
= next
)
3433 next
= XEXP (note
, 1);
3435 if (REG_NOTE_KIND (note
) != REG_DEAD
3436 /* Verify that the REG_NOTE is legitimate. */
3437 || GET_CODE (XEXP (note
, 0)) != REG
3438 || ! reg_mentioned_p (XEXP (note
, 0), PATTERN (jump
)))
3439 notep
= &XEXP (note
, 1);
3442 delete_prior_computation (note
, jump
);
3447 PATTERN (jump
) = gen_jump (nlabel
);
3448 JUMP_LABEL (jump
) = nlabel
;
3449 ++LABEL_NUSES (nlabel
);
3450 INSN_CODE (jump
) = -1;
3452 if (--LABEL_NUSES (olabel
) == 0)
3454 delete_labelref_insn (jump
, olabel
, 0);
3455 delete_insn (olabel
);
3459 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3460 If we found one, delete it and then delete this insn if DELETE_THIS is
3461 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3464 delete_labelref_insn (insn
, label
, delete_this
)
3471 if (GET_CODE (insn
) != NOTE
3472 && reg_mentioned_p (label
, PATTERN (insn
)))
3483 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
3484 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
3498 /* Like rtx_equal_p except that it considers two REGs as equal
3499 if they renumber to the same value and considers two commutative
3500 operations to be the same if the order of the operands has been
3503 ??? Addition is not commutative on the PA due to the weird implicit
3504 space register selection rules for memory addresses. Therefore, we
3505 don't consider a + b == b + a.
3507 We could/should make this test a little tighter. Possibly only
3508 disabling it on the PA via some backend macro or only disabling this
3509 case when the PLUS is inside a MEM. */
3512 rtx_renumbered_equal_p (x
, y
)
3516 register RTX_CODE code
= GET_CODE (x
);
3517 register const char *fmt
;
3522 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
3523 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
3524 && GET_CODE (SUBREG_REG (y
)) == REG
)))
3526 int reg_x
= -1, reg_y
= -1;
3527 int byte_x
= 0, byte_y
= 0;
3529 if (GET_MODE (x
) != GET_MODE (y
))
3532 /* If we haven't done any renumbering, don't
3533 make any assumptions. */
3534 if (reg_renumber
== 0)
3535 return rtx_equal_p (x
, y
);
3539 reg_x
= REGNO (SUBREG_REG (x
));
3540 byte_x
= SUBREG_BYTE (x
);
3542 if (reg_renumber
[reg_x
] >= 0)
3544 reg_x
= subreg_regno_offset (reg_renumber
[reg_x
],
3545 GET_MODE (SUBREG_REG (x
)),
3554 if (reg_renumber
[reg_x
] >= 0)
3555 reg_x
= reg_renumber
[reg_x
];
3558 if (GET_CODE (y
) == SUBREG
)
3560 reg_y
= REGNO (SUBREG_REG (y
));
3561 byte_y
= SUBREG_BYTE (y
);
3563 if (reg_renumber
[reg_y
] >= 0)
3565 reg_y
= subreg_regno_offset (reg_renumber
[reg_y
],
3566 GET_MODE (SUBREG_REG (y
)),
3575 if (reg_renumber
[reg_y
] >= 0)
3576 reg_y
= reg_renumber
[reg_y
];
3579 return reg_x
>= 0 && reg_x
== reg_y
&& byte_x
== byte_y
;
3582 /* Now we have disposed of all the cases
3583 in which different rtx codes can match. */
3584 if (code
!= GET_CODE (y
))
3596 return INTVAL (x
) == INTVAL (y
);
3599 /* We can't assume nonlocal labels have their following insns yet. */
3600 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
3601 return XEXP (x
, 0) == XEXP (y
, 0);
3603 /* Two label-refs are equivalent if they point at labels
3604 in the same position in the instruction stream. */
3605 return (next_real_insn (XEXP (x
, 0))
3606 == next_real_insn (XEXP (y
, 0)));
3609 return XSTR (x
, 0) == XSTR (y
, 0);
3612 /* If we didn't match EQ equality above, they aren't the same. */
3619 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3621 if (GET_MODE (x
) != GET_MODE (y
))
3624 /* For commutative operations, the RTX match if the operand match in any
3625 order. Also handle the simple binary and unary cases without a loop.
3627 ??? Don't consider PLUS a commutative operator; see comments above. */
3628 if ((code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
3630 return ((rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
3631 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)))
3632 || (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 1))
3633 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 0))));
3634 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
3635 return (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
3636 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)));
3637 else if (GET_RTX_CLASS (code
) == '1')
3638 return rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0));
3640 /* Compare the elements. If any pair of corresponding elements
3641 fail to match, return 0 for the whole things. */
3643 fmt
= GET_RTX_FORMAT (code
);
3644 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3650 if (XWINT (x
, i
) != XWINT (y
, i
))
3655 if (XINT (x
, i
) != XINT (y
, i
))
3660 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
3665 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
3670 if (XEXP (x
, i
) != XEXP (y
, i
))
3677 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
3679 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
3680 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
3691 /* If X is a hard register or equivalent to one or a subregister of one,
3692 return the hard register number. If X is a pseudo register that was not
3693 assigned a hard register, return the pseudo register number. Otherwise,
3694 return -1. Any rtx is valid for X. */
3700 if (GET_CODE (x
) == REG
)
3702 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
3703 return reg_renumber
[REGNO (x
)];
3706 if (GET_CODE (x
) == SUBREG
)
3708 int base
= true_regnum (SUBREG_REG (x
));
3709 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
3710 return base
+ subreg_regno_offset (REGNO (SUBREG_REG (x
)),
3711 GET_MODE (SUBREG_REG (x
)),
3712 SUBREG_BYTE (x
), GET_MODE (x
));
3717 /* Optimize code of the form:
3719 for (x = a[i]; x; ...)
3721 for (x = a[i]; x; ...)
3725 Loop optimize will change the above code into
3729 { ...; if (! (x = ...)) break; }
3732 { ...; if (! (x = ...)) break; }
3735 In general, if the first test fails, the program can branch
3736 directly to `foo' and skip the second try which is doomed to fail.
3737 We run this after loop optimization and before flow analysis. */
3739 /* When comparing the insn patterns, we track the fact that different
3740 pseudo-register numbers may have been used in each computation.
3741 The following array stores an equivalence -- same_regs[I] == J means
3742 that pseudo register I was used in the first set of tests in a context
3743 where J was used in the second set. We also count the number of such
3744 pending equivalences. If nonzero, the expressions really aren't the
3747 static int *same_regs
;
3749 static int num_same_regs
;
3751 /* Track any registers modified between the target of the first jump and
3752 the second jump. They never compare equal. */
3754 static char *modified_regs
;
3756 /* Record if memory was modified. */
3758 static int modified_mem
;
3760 /* Called via note_stores on each insn between the target of the first
3761 branch and the second branch. It marks any changed registers. */
3764 mark_modified_reg (dest
, x
, data
)
3767 void *data ATTRIBUTE_UNUSED
;
3772 if (GET_CODE (dest
) == SUBREG
)
3773 dest
= SUBREG_REG (dest
);
3775 if (GET_CODE (dest
) == MEM
)
3778 if (GET_CODE (dest
) != REG
)
3781 regno
= REGNO (dest
);
3782 if (regno
>= FIRST_PSEUDO_REGISTER
)
3783 modified_regs
[regno
] = 1;
3784 /* Don't consider a hard condition code register as modified,
3785 if it is only being set. thread_jumps will check if it is set
3786 to the same value. */
3787 else if (GET_MODE_CLASS (GET_MODE (dest
)) != MODE_CC
3788 || GET_CODE (x
) != SET
3789 || ! rtx_equal_p (dest
, SET_DEST (x
))
3790 || HARD_REGNO_NREGS (regno
, GET_MODE (dest
)) != 1)
3791 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
3792 modified_regs
[regno
+ i
] = 1;
3795 /* F is the first insn in the chain of insns. */
3798 thread_jumps (f
, max_reg
, flag_before_loop
)
3801 int flag_before_loop
;
3803 /* Basic algorithm is to find a conditional branch,
3804 the label it may branch to, and the branch after
3805 that label. If the two branches test the same condition,
3806 walk back from both branch paths until the insn patterns
3807 differ, or code labels are hit. If we make it back to
3808 the target of the first branch, then we know that the first branch
3809 will either always succeed or always fail depending on the relative
3810 senses of the two branches. So adjust the first branch accordingly
3813 rtx label
, b1
, b2
, t1
, t2
;
3814 enum rtx_code code1
, code2
;
3815 rtx b1op0
, b1op1
, b2op0
, b2op1
;
3819 enum rtx_code reversed_code1
, reversed_code2
;
3821 /* Allocate register tables and quick-reset table. */
3822 modified_regs
= (char *) xmalloc (max_reg
* sizeof (char));
3823 same_regs
= (int *) xmalloc (max_reg
* sizeof (int));
3824 all_reset
= (int *) xmalloc (max_reg
* sizeof (int));
3825 for (i
= 0; i
< max_reg
; i
++)
3832 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
3837 /* Get to a candidate branch insn. */
3838 if (GET_CODE (b1
) != JUMP_INSN
3839 || ! any_condjump_p (b1
) || JUMP_LABEL (b1
) == 0)
3842 memset (modified_regs
, 0, max_reg
* sizeof (char));
3845 memcpy (same_regs
, all_reset
, max_reg
* sizeof (int));
3848 label
= JUMP_LABEL (b1
);
3850 /* Look for a branch after the target. Record any registers and
3851 memory modified between the target and the branch. Stop when we
3852 get to a label since we can't know what was changed there. */
3853 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
3855 if (GET_CODE (b2
) == CODE_LABEL
)
3858 else if (GET_CODE (b2
) == JUMP_INSN
)
3860 /* If this is an unconditional jump and is the only use of
3861 its target label, we can follow it. */
3862 if (any_uncondjump_p (b2
)
3864 && JUMP_LABEL (b2
) != 0
3865 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
3867 b2
= JUMP_LABEL (b2
);
3874 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
3877 if (GET_CODE (b2
) == CALL_INSN
)
3880 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3881 if (call_used_regs
[i
] && ! fixed_regs
[i
]
3882 && i
!= STACK_POINTER_REGNUM
3883 && i
!= FRAME_POINTER_REGNUM
3884 && i
!= HARD_FRAME_POINTER_REGNUM
3885 && i
!= ARG_POINTER_REGNUM
)
3886 modified_regs
[i
] = 1;
3889 note_stores (PATTERN (b2
), mark_modified_reg
, NULL
);
3892 /* Check the next candidate branch insn from the label
3895 || GET_CODE (b2
) != JUMP_INSN
3897 || !any_condjump_p (b2
)
3898 || !onlyjump_p (b2
))
3903 /* Get the comparison codes and operands, reversing the
3904 codes if appropriate. If we don't have comparison codes,
3905 we can't do anything. */
3906 b1op0
= XEXP (XEXP (SET_SRC (set
), 0), 0);
3907 b1op1
= XEXP (XEXP (SET_SRC (set
), 0), 1);
3908 code1
= GET_CODE (XEXP (SET_SRC (set
), 0));
3909 reversed_code1
= code1
;
3910 if (XEXP (SET_SRC (set
), 1) == pc_rtx
)
3911 code1
= reversed_comparison_code (XEXP (SET_SRC (set
), 0), b1
);
3913 reversed_code1
= reversed_comparison_code (XEXP (SET_SRC (set
), 0), b1
);
3915 b2op0
= XEXP (XEXP (SET_SRC (set2
), 0), 0);
3916 b2op1
= XEXP (XEXP (SET_SRC (set2
), 0), 1);
3917 code2
= GET_CODE (XEXP (SET_SRC (set2
), 0));
3918 reversed_code2
= code2
;
3919 if (XEXP (SET_SRC (set2
), 1) == pc_rtx
)
3920 code2
= reversed_comparison_code (XEXP (SET_SRC (set2
), 0), b2
);
3922 reversed_code2
= reversed_comparison_code (XEXP (SET_SRC (set2
), 0), b2
);
3924 /* If they test the same things and knowing that B1 branches
3925 tells us whether or not B2 branches, check if we
3926 can thread the branch. */
3927 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
3928 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
3929 && (comparison_dominates_p (code1
, code2
)
3930 || comparison_dominates_p (code1
, reversed_code2
)))
3933 t1
= prev_nonnote_insn (b1
);
3934 t2
= prev_nonnote_insn (b2
);
3936 while (t1
!= 0 && t2
!= 0)
3940 /* We have reached the target of the first branch.
3941 If there are no pending register equivalents,
3942 we know that this branch will either always
3943 succeed (if the senses of the two branches are
3944 the same) or always fail (if not). */
3947 if (num_same_regs
!= 0)
3950 if (comparison_dominates_p (code1
, code2
))
3951 new_label
= JUMP_LABEL (b2
);
3953 new_label
= get_label_after (b2
);
3955 if (JUMP_LABEL (b1
) != new_label
)
3957 rtx prev
= PREV_INSN (new_label
);
3959 if (flag_before_loop
3960 && GET_CODE (prev
) == NOTE
3961 && NOTE_LINE_NUMBER (prev
) == NOTE_INSN_LOOP_BEG
)
3963 /* Don't thread to the loop label. If a loop
3964 label is reused, loop optimization will
3965 be disabled for that loop. */
3966 new_label
= gen_label_rtx ();
3967 emit_label_after (new_label
, PREV_INSN (prev
));
3969 changed
|= redirect_jump (b1
, new_label
, 1);
3974 /* If either of these is not a normal insn (it might be
3975 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3976 have already been skipped above.) Similarly, fail
3977 if the insns are different. */
3978 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
3979 || recog_memoized (t1
) != recog_memoized (t2
)
3980 || ! rtx_equal_for_thread_p (PATTERN (t1
),
3984 t1
= prev_nonnote_insn (t1
);
3985 t2
= prev_nonnote_insn (t2
);
3992 free (modified_regs
);
3997 /* This is like RTX_EQUAL_P except that it knows about our handling of
3998 possibly equivalent registers and knows to consider volatile and
3999 modified objects as not equal.
4001 YINSN is the insn containing Y. */
4004 rtx_equal_for_thread_p (x
, y
, yinsn
)
4010 register enum rtx_code code
;
4011 register const char *fmt
;
4013 code
= GET_CODE (x
);
4014 /* Rtx's of different codes cannot be equal. */
4015 if (code
!= GET_CODE (y
))
4018 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4019 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4021 if (GET_MODE (x
) != GET_MODE (y
))
4024 /* For floating-point, consider everything unequal. This is a bit
4025 pessimistic, but this pass would only rarely do anything for FP
4027 if (TARGET_FLOAT_FORMAT
== IEEE_FLOAT_FORMAT
4028 && FLOAT_MODE_P (GET_MODE (x
)) && ! flag_unsafe_math_optimizations
)
4031 /* For commutative operations, the RTX match if the operand match in any
4032 order. Also handle the simple binary and unary cases without a loop. */
4033 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4034 return ((rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4035 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
))
4036 || (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 1), yinsn
)
4037 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 0), yinsn
)));
4038 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4039 return (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4040 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
));
4041 else if (GET_RTX_CLASS (code
) == '1')
4042 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4044 /* Handle special-cases first. */
4048 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
4051 /* If neither is user variable or hard register, check for possible
4053 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
4054 || REGNO (x
) < FIRST_PSEUDO_REGISTER
4055 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
4058 if (same_regs
[REGNO (x
)] == -1)
4060 same_regs
[REGNO (x
)] = REGNO (y
);
4063 /* If this is the first time we are seeing a register on the `Y'
4064 side, see if it is the last use. If not, we can't thread the
4065 jump, so mark it as not equivalent. */
4066 if (REGNO_LAST_UID (REGNO (y
)) != INSN_UID (yinsn
))
4072 return (same_regs
[REGNO (x
)] == (int) REGNO (y
));
4077 /* If memory modified or either volatile, not equivalent.
4078 Else, check address. */
4079 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4082 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4085 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4091 /* Cancel a pending `same_regs' if setting equivalenced registers.
4092 Then process source. */
4093 if (GET_CODE (SET_DEST (x
)) == REG
4094 && GET_CODE (SET_DEST (y
)) == REG
)
4096 if (same_regs
[REGNO (SET_DEST (x
))] == (int) REGNO (SET_DEST (y
)))
4098 same_regs
[REGNO (SET_DEST (x
))] = -1;
4101 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
4106 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
4110 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
4113 return XEXP (x
, 0) == XEXP (y
, 0);
4116 return XSTR (x
, 0) == XSTR (y
, 0);
4125 fmt
= GET_RTX_FORMAT (code
);
4126 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4131 if (XWINT (x
, i
) != XWINT (y
, i
))
4137 if (XINT (x
, i
) != XINT (y
, i
))
4143 /* Two vectors must have the same length. */
4144 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4147 /* And the corresponding elements must match. */
4148 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4149 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
4150 XVECEXP (y
, i
, j
), yinsn
) == 0)
4155 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
4161 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4166 /* These are just backpointers, so they don't matter. */
4173 /* It is believed that rtx's at this level will never
4174 contain anything but integers and other rtx's,
4175 except for within LABEL_REFs and SYMBOL_REFs. */