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gcc.gnu.org Git - gcc.git/blob - gcc/jump.c
1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This is the jump-optimization pass of the compiler.
22 It is run two or three times: once before cse, sometimes once after cse,
23 and once after reload (before final).
25 jump_optimize deletes unreachable code and labels that are not used.
26 It also deletes jumps that jump to the following insn,
27 and simplifies jumps around unconditional jumps and jumps
28 to unconditional jumps.
30 Each CODE_LABEL has a count of the times it is used
31 stored in the LABEL_NUSES internal field, and each JUMP_INSN
32 has one label that it refers to stored in the
33 JUMP_LABEL internal field. With this we can detect labels that
34 become unused because of the deletion of all the jumps that
35 formerly used them. The JUMP_LABEL info is sometimes looked
38 Optionally, cross-jumping can be done. Currently it is done
39 only the last time (when after reload and before final).
40 In fact, the code for cross-jumping now assumes that register
41 allocation has been done, since it uses `rtx_renumbered_equal_p'.
43 Jump optimization is done after cse when cse's constant-propagation
44 causes jumps to become unconditional or to be deleted.
46 Unreachable loops are not detected here, because the labels
47 have references and the insns appear reachable from the labels.
48 find_basic_blocks in flow.c finds and deletes such loops.
50 The subroutines delete_insn, redirect_jump, and invert_jump are used
51 from other passes as well. */
56 #include "hard-reg-set.h"
59 #include "insn-config.h"
60 #include "insn-flags.h"
63 /* ??? Eventually must record somehow the labels used by jumps
64 from nested functions. */
65 /* Pre-record the next or previous real insn for each label?
66 No, this pass is very fast anyway. */
67 /* Condense consecutive labels?
68 This would make life analysis faster, maybe. */
69 /* Optimize jump y; x: ... y: jumpif... x?
70 Don't know if it is worth bothering with. */
71 /* Optimize two cases of conditional jump to conditional jump?
72 This can never delete any instruction or make anything dead,
73 or even change what is live at any point.
74 So perhaps let combiner do it. */
76 /* Vector indexed by uid.
77 For each CODE_LABEL, index by its uid to get first unconditional jump
78 that jumps to the label.
79 For each JUMP_INSN, index by its uid to get the next unconditional jump
80 that jumps to the same label.
81 Element 0 is the start of a chain of all return insns.
82 (It is safe to use element 0 because insn uid 0 is not used. */
84 static rtx
*jump_chain
;
86 /* List of labels referred to from initializers.
87 These can never be deleted. */
90 /* Maximum index in jump_chain. */
92 static int max_jump_chain
;
94 /* Set nonzero by jump_optimize if control can fall through
95 to the end of the function. */
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 duplicate_loop_exit_test ();
108 int redirect_jump ();
109 static int redirect_exp ();
110 void redirect_tablejump ();
111 static int delete_labelref_insn ();
113 static int invert_exp ();
117 extern rtx
gen_jump ();
119 static void mark_jump_label ();
121 static void delete_from_jump_chain ();
122 static int tension_vector_labels ();
123 static void find_cross_jump ();
124 static void do_cross_jump ();
125 static int jump_back_p ();
127 /* Delete no-op jumps and optimize jumps to jumps
128 and jumps around jumps.
129 Delete unused labels and unreachable code.
131 If CROSS_JUMP is 1, detect matching code
132 before a jump and its destination and unify them.
133 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
135 If NOOP_MOVES is nonzero, delete no-op move insns.
137 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
138 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
140 If `optimize' is zero, don't change any code,
141 just determine whether control drops off the end of the function.
142 This case occurs when we have -W and not -O.
143 It works because `delete_insn' checks the value of `optimize'
144 and refrains from actually deleting when that is 0. */
147 jump_optimize (f
, cross_jump
, noop_moves
, after_regscan
)
159 cross_jump_death_matters
= (cross_jump
== 2);
161 /* Initialize LABEL_NUSES and JUMP_LABEL fields. */
163 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
165 if (GET_CODE (insn
) == CODE_LABEL
)
166 LABEL_NUSES (insn
) = (LABEL_PRESERVE_P (insn
) != 0);
167 else if (GET_CODE (insn
) == JUMP_INSN
)
168 JUMP_LABEL (insn
) = 0;
169 if (INSN_UID (insn
) > max_uid
)
170 max_uid
= INSN_UID (insn
);
175 /* Delete insns following barriers, up to next label. */
177 for (insn
= f
; insn
;)
179 if (GET_CODE (insn
) == BARRIER
)
181 insn
= NEXT_INSN (insn
);
182 while (insn
!= 0 && GET_CODE (insn
) != CODE_LABEL
)
184 if (GET_CODE (insn
) == NOTE
185 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
186 insn
= NEXT_INSN (insn
);
188 insn
= delete_insn (insn
);
190 /* INSN is now the code_label. */
193 insn
= NEXT_INSN (insn
);
196 /* Leave some extra room for labels and duplicate exit test insns
198 max_jump_chain
= max_uid
* 14 / 10;
199 jump_chain
= (rtx
*) alloca (max_jump_chain
* sizeof (rtx
));
200 bzero (jump_chain
, max_jump_chain
* sizeof (rtx
));
202 /* Mark the label each jump jumps to.
203 Combine consecutive labels, and count uses of labels.
205 For each label, make a chain (using `jump_chain')
206 of all the *unconditional* jumps that jump to it;
207 also make a chain of all returns. */
209 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
210 if ((GET_CODE (insn
) == JUMP_INSN
|| GET_CODE (insn
) == INSN
211 || GET_CODE (insn
) == CALL_INSN
)
212 && ! INSN_DELETED_P (insn
))
214 mark_jump_label (PATTERN (insn
), insn
, cross_jump
);
215 if (GET_CODE (insn
) == JUMP_INSN
)
217 if (JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
219 jump_chain
[INSN_UID (insn
)]
220 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
221 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
223 if (GET_CODE (PATTERN (insn
)) == RETURN
)
225 jump_chain
[INSN_UID (insn
)] = jump_chain
[0];
226 jump_chain
[0] = insn
;
231 /* Keep track of labels used from static data;
232 they cannot ever be deleted. */
234 for (insn
= forced_labels
; insn
; insn
= XEXP (insn
, 1))
235 LABEL_NUSES (XEXP (insn
, 0))++;
237 /* Delete all labels already not referenced.
238 Also find the last insn. */
241 for (insn
= f
; insn
; )
243 if (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NUSES (insn
) == 0)
244 insn
= delete_insn (insn
);
248 insn
= NEXT_INSN (insn
);
254 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
255 If so record that this function can drop off the end. */
261 /* One label can follow the end-note: the return label. */
262 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
263 /* Ordinary insns can follow it if returning a structure. */
264 || GET_CODE (insn
) == INSN
265 /* If machine uses explicit RETURN insns, no epilogue,
266 then one of them follows the note. */
267 || (GET_CODE (insn
) == JUMP_INSN
268 && GET_CODE (PATTERN (insn
)) == RETURN
)
269 /* Other kinds of notes can follow also. */
270 || (GET_CODE (insn
) == NOTE
271 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
272 insn
= PREV_INSN (insn
);
275 /* Report if control can fall through at the end of the function. */
276 if (insn
&& GET_CODE (insn
) == NOTE
277 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
278 && ! INSN_DELETED_P (insn
))
281 /* Zero the "deleted" flag of all the "deleted" insns. */
282 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
283 INSN_DELETED_P (insn
) = 0;
290 /* If we fall through to the epilogue, see if we can insert a RETURN insn
291 in front of it. If the machine allows it at this point (we might be
292 after reload for a leaf routine), it will improve optimization for it
294 insn
= get_last_insn ();
295 while (insn
&& GET_CODE (insn
) == NOTE
)
296 insn
= PREV_INSN (insn
);
298 if (insn
&& GET_CODE (insn
) != BARRIER
)
300 emit_jump_insn (gen_return ());
307 for (insn
= f
; insn
; )
309 register rtx next
= NEXT_INSN (insn
);
311 if (GET_CODE (insn
) == INSN
)
313 register rtx body
= PATTERN (insn
);
315 /* Combine stack_adjusts with following push_insns. */
317 if (GET_CODE (body
) == SET
318 && SET_DEST (body
) == stack_pointer_rtx
319 && GET_CODE (SET_SRC (body
)) == PLUS
320 && XEXP (SET_SRC (body
), 0) == stack_pointer_rtx
321 && GET_CODE (XEXP (SET_SRC (body
), 1)) == CONST_INT
322 && INTVAL (XEXP (SET_SRC (body
), 1)) > 0)
325 rtx stack_adjust_insn
= insn
;
326 int stack_adjust_amount
= INTVAL (XEXP (SET_SRC (body
), 1));
327 int total_pushed
= 0;
330 /* Find all successive push insns. */
332 /* Don't convert more than three pushes;
333 that starts adding too many displaced addresses
334 and the whole thing starts becoming a losing
339 p
= next_nonnote_insn (p
);
340 if (p
== 0 || GET_CODE (p
) != INSN
)
343 if (GET_CODE (pbody
) != SET
)
345 dest
= SET_DEST (pbody
);
346 /* Allow a no-op move between the adjust and the push. */
347 if (GET_CODE (dest
) == REG
348 && GET_CODE (SET_SRC (pbody
)) == REG
349 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
351 if (! (GET_CODE (dest
) == MEM
352 && GET_CODE (XEXP (dest
, 0)) == POST_INC
353 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
356 if (total_pushed
+ GET_MODE_SIZE (SET_DEST (pbody
))
357 > stack_adjust_amount
)
359 total_pushed
+= GET_MODE_SIZE (SET_DEST (pbody
));
362 /* Discard the amount pushed from the stack adjust;
363 maybe eliminate it entirely. */
364 if (total_pushed
>= stack_adjust_amount
)
366 delete_insn (stack_adjust_insn
);
367 total_pushed
= stack_adjust_amount
;
370 XEXP (SET_SRC (PATTERN (stack_adjust_insn
)), 1)
371 = gen_rtx (CONST_INT
, VOIDmode
,
372 stack_adjust_amount
- total_pushed
);
374 /* Change the appropriate push insns to ordinary stores. */
376 while (total_pushed
> 0)
379 p
= next_nonnote_insn (p
);
380 if (GET_CODE (p
) != INSN
)
383 if (GET_CODE (pbody
) == SET
)
385 dest
= SET_DEST (pbody
);
386 if (! (GET_CODE (dest
) == MEM
387 && GET_CODE (XEXP (dest
, 0)) == POST_INC
388 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
390 total_pushed
-= GET_MODE_SIZE (SET_DEST (pbody
));
391 /* If this push doesn't fully fit in the space
392 of the stack adjust that we deleted,
393 make another stack adjust here for what we
394 didn't use up. There should be peepholes
395 to recognize the resulting sequence of insns. */
396 if (total_pushed
< 0)
398 emit_insn_before (gen_add2_insn (stack_pointer_rtx
,
399 gen_rtx (CONST_INT
, VOIDmode
, - total_pushed
)),
404 = plus_constant (stack_pointer_rtx
, total_pushed
);
409 /* Detect and delete no-op move instructions
410 resulting from not allocating a parameter in a register. */
412 if (GET_CODE (body
) == SET
413 && (SET_DEST (body
) == SET_SRC (body
)
414 || (GET_CODE (SET_DEST (body
)) == MEM
415 && GET_CODE (SET_SRC (body
)) == MEM
416 && rtx_equal_p (SET_SRC (body
), SET_DEST (body
))))
417 && ! (GET_CODE (SET_DEST (body
)) == MEM
418 && MEM_VOLATILE_P (SET_DEST (body
)))
419 && ! (GET_CODE (SET_SRC (body
)) == MEM
420 && MEM_VOLATILE_P (SET_SRC (body
))))
423 /* Detect and ignore no-op move instructions
424 resulting from smart or fortuitous register allocation. */
426 else if (GET_CODE (body
) == SET
)
428 int sreg
= true_regnum (SET_SRC (body
));
429 int dreg
= true_regnum (SET_DEST (body
));
431 if (sreg
== dreg
&& sreg
>= 0)
433 else if (sreg
>= 0 && dreg
>= 0)
436 rtx tem
= find_equiv_reg (0, insn
, 0,
438 GET_MODE (SET_SRC (body
)));
440 #ifdef PRESERVE_DEATH_INFO_REGNO_P
441 /* Deleting insn could lose a death-note for SREG or DREG
442 so don't do it if final needs accurate death-notes. */
443 if (! PRESERVE_DEATH_INFO_REGNO_P (sreg
)
444 && ! PRESERVE_DEATH_INFO_REGNO_P (dreg
))
447 /* DREG may have been the target of a REG_DEAD note in
448 the insn which makes INSN redundant. If so, reorg
449 would still think it is dead. So search for such a
450 note and delete it if we find it. */
451 for (trial
= prev_nonnote_insn (insn
);
452 trial
&& GET_CODE (trial
) != CODE_LABEL
;
453 trial
= prev_nonnote_insn (trial
))
454 if (find_regno_note (trial
, REG_DEAD
, dreg
))
456 remove_death (dreg
, trial
);
461 && GET_MODE (tem
) == GET_MODE (SET_DEST (body
)))
465 else if (dreg
>= 0 && CONSTANT_P (SET_SRC (body
))
466 && find_equiv_reg (SET_SRC (body
), insn
, 0, dreg
, 0,
467 0, GET_MODE (SET_DEST (body
))))
469 /* This handles the case where we have two consecutive
470 assignments of the same constant to pseudos that didn't
471 get a hard reg. Each SET from the constant will be
472 converted into a SET of the spill register and an
473 output reload will be made following it. This produces
474 two loads of the same constant into the same spill
479 /* Look back for a death note for the first reg.
480 If there is one, it is no longer accurate. */
481 while (in_insn
&& GET_CODE (in_insn
) != CODE_LABEL
)
483 if ((GET_CODE (in_insn
) == INSN
484 || GET_CODE (in_insn
) == JUMP_INSN
)
485 && find_regno_note (in_insn
, REG_DEAD
, dreg
))
487 remove_death (dreg
, in_insn
);
490 in_insn
= PREV_INSN (in_insn
);
493 /* Delete the second load of the value. */
497 else if (GET_CODE (body
) == PARALLEL
)
499 /* If each part is a set between two identical registers or
500 a USE or CLOBBER, delete the insn. */
504 for (i
= XVECLEN (body
, 0) - 1; i
>= 0; i
--)
506 tem
= XVECEXP (body
, 0, i
);
507 if (GET_CODE (tem
) == USE
|| GET_CODE (tem
) == CLOBBER
)
510 if (GET_CODE (tem
) != SET
511 || (sreg
= true_regnum (SET_SRC (tem
))) < 0
512 || (dreg
= true_regnum (SET_DEST (tem
))) < 0
520 #if !BYTES_BIG_ENDIAN /* Not worth the hair to detect this
521 in the big-endian case. */
522 /* Also delete insns to store bit fields if they are no-ops. */
523 else if (GET_CODE (body
) == SET
524 && GET_CODE (SET_DEST (body
)) == ZERO_EXTRACT
525 && XEXP (SET_DEST (body
), 2) == const0_rtx
526 && XEXP (SET_DEST (body
), 0) == SET_SRC (body
)
527 && ! (GET_CODE (SET_SRC (body
)) == MEM
528 && MEM_VOLATILE_P (SET_SRC (body
))))
530 #endif /* not BYTES_BIG_ENDIAN */
535 /* Now iterate optimizing jumps until nothing changes over one pass. */
542 for (insn
= f
; insn
; insn
= next
)
545 rtx temp
, temp1
, temp2
, temp3
, temp4
, temp5
;
547 int this_is_simplejump
, this_is_condjump
;
549 /* If NOT the first iteration, if this is the last jump pass
550 (just before final), do the special peephole optimizations.
551 Avoiding the first iteration gives ordinary jump opts
552 a chance to work before peephole opts. */
554 if (reload_completed
&& !first
&& !flag_no_peephole
)
555 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
559 /* That could have deleted some insns after INSN, so check now
560 what the following insn is. */
562 next
= NEXT_INSN (insn
);
564 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
565 jump. Try to optimize by duplicating the loop exit test if so.
566 This is only safe immediately after regscan, because it uses
567 the values of regno_first_uid and regno_last_uid. */
568 if (after_regscan
&& GET_CODE (insn
) == NOTE
569 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
570 && (temp1
= next_nonnote_insn (insn
)) != 0
571 && simplejump_p (temp1
))
573 temp
= PREV_INSN (insn
);
574 if (duplicate_loop_exit_test (insn
))
577 next
= NEXT_INSN (temp
);
582 if (GET_CODE (insn
) != JUMP_INSN
)
585 this_is_simplejump
= simplejump_p (insn
);
586 this_is_condjump
= condjump_p (insn
);
588 /* Tension the labels in dispatch tables. */
590 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
591 changed
|= tension_vector_labels (PATTERN (insn
), 0);
592 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
593 changed
|= tension_vector_labels (PATTERN (insn
), 1);
595 /* If a dispatch table always goes to the same place,
596 get rid of it and replace the insn that uses it. */
598 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
599 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
602 rtx pat
= PATTERN (insn
);
603 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
604 int len
= XVECLEN (pat
, diff_vec_p
);
605 rtx dispatch
= prev_real_insn (insn
);
607 for (i
= 0; i
< len
; i
++)
608 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
609 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
612 && GET_CODE (dispatch
) == JUMP_INSN
613 && JUMP_LABEL (dispatch
) != 0
614 /* Don't mess with a casesi insn. */
615 && !(GET_CODE (PATTERN (dispatch
)) == SET
616 && (GET_CODE (SET_SRC (PATTERN (dispatch
)))
618 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
620 redirect_tablejump (dispatch
,
621 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
626 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
628 /* If a jump references the end of the function, try to turn
629 it into a RETURN insn, possibly a conditional one. */
630 if (JUMP_LABEL (insn
)
631 && next_active_insn (JUMP_LABEL (insn
)) == 0)
632 changed
|= redirect_jump (insn
, 0);
634 /* Detect jump to following insn. */
635 if (reallabelprev
== insn
&& condjump_p (insn
))
642 /* If we have an unconditional jump preceded by a USE, try to put
643 the USE before the target and jump there. This simplifies many
644 of the optimizations below since we don't have to worry about
645 dealing with these USE insns. We only do this if the label
646 being branch to already has the identical USE or if code
647 never falls through to that label. */
649 if (this_is_simplejump
650 && (temp
= prev_nonnote_insn (insn
)) != 0
651 && GET_CODE (temp
) == INSN
&& GET_CODE (PATTERN (temp
)) == USE
652 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
653 && (GET_CODE (temp1
) == BARRIER
654 || (GET_CODE (temp1
) == INSN
655 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
)))))
657 if (GET_CODE (temp1
) == BARRIER
)
659 reorder_insns (temp
, temp
, temp1
);
660 temp1
= NEXT_INSN (temp1
);
665 redirect_jump (insn
, get_label_before (temp1
));
666 reallabelprev
= prev_real_insn (temp1
);
670 /* Simplify if (...) x = a; else x = b; by converting it
671 to x = b; if (...) x = a;
672 if B is sufficiently simple, the test doesn't involve X,
673 and nothing in the test modifies B or X.
675 If we have small register classes, we also can't do this if X
678 If the "x = b;" insn has any REG_NOTES, we don't do this because
679 of the possibility that we are running after CSE and there is a
680 REG_EQUAL note that is only valid if the branch has already been
681 taken. If we move the insn with the REG_EQUAL note, we may
682 fold the comparison to always be false in a later CSE pass.
683 (We could also delete the REG_NOTES when moving the insn, but it
684 seems simpler to not move it.) An exception is that we can move
685 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
686 value is the same as "b".
688 INSN is the branch over the `else' part.
692 TEMP to the jump insn preceding "x = a;"
694 TEMP2 to the insn that sets "x = b;"
695 TEMP3 to the insn that sets "x = a;" */
697 if (this_is_simplejump
698 && (temp3
= prev_active_insn (insn
)) != 0
699 && GET_CODE (temp3
) == INSN
700 && GET_CODE (PATTERN (temp3
)) == SET
701 && GET_CODE (temp1
= SET_DEST (PATTERN (temp3
))) == REG
702 #ifdef SMALL_REGISTER_CLASSES
703 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
705 && (temp2
= next_active_insn (insn
)) != 0
706 && GET_CODE (temp2
) == INSN
707 && GET_CODE (PATTERN (temp2
)) == SET
708 && rtx_equal_p (SET_DEST (PATTERN (temp2
)), temp1
)
709 && (GET_CODE (SET_SRC (PATTERN (temp2
))) == REG
710 || CONSTANT_P (SET_SRC (PATTERN (temp2
))))
711 && (REG_NOTES (temp2
) == 0
712 || ((REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUAL
713 || REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUIV
)
714 && XEXP (REG_NOTES (temp2
), 1) == 0
715 && rtx_equal_p (XEXP (REG_NOTES (temp2
), 0),
716 SET_SRC (PATTERN (temp2
)))))
717 && (temp
= prev_active_insn (temp3
)) != 0
718 && condjump_p (temp
) && ! simplejump_p (temp
)
719 /* TEMP must skip over the "x = a;" insn */
720 && prev_real_insn (JUMP_LABEL (temp
)) == insn
721 && no_labels_between_p (insn
, JUMP_LABEL (temp
))
722 /* There must be no other entries to the "x = b;" insn. */
723 && no_labels_between_p (JUMP_LABEL (temp
), temp2
)
724 /* INSN must either branch to the insn after TEMP2 or the insn
725 after TEMP2 must branch to the same place as INSN. */
726 && (reallabelprev
== temp2
727 || ((temp4
= next_active_insn (temp2
)) != 0
728 && simplejump_p (temp4
)
729 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
))))
731 /* The test expression, X, may be a complicated test with
732 multiple branches. See if we can find all the uses of
733 the label that TEMP branches to without hitting a CALL_INSN
734 or a jump to somewhere else. */
735 rtx target
= JUMP_LABEL (temp
);
736 int nuses
= LABEL_NUSES (target
);
739 /* Set P to the first jump insn that goes around "x = a;". */
740 for (p
= temp
; nuses
&& p
; p
= prev_nonnote_insn (p
))
742 if (GET_CODE (p
) == JUMP_INSN
)
744 if (condjump_p (p
) && ! simplejump_p (p
)
745 && JUMP_LABEL (p
) == target
)
754 else if (GET_CODE (p
) == CALL_INSN
)
759 /* We cannot insert anything between a set of cc and its use
760 so if P uses cc0, we must back up to the previous insn. */
761 q
= prev_nonnote_insn (p
);
762 if (q
&& GET_RTX_CLASS (GET_CODE (q
)) == 'i'
763 && sets_cc0_p (PATTERN (q
)))
770 /* If we found all the uses and there was no data conflict, we
771 can move the assignment unless we can branch into the middle
774 && no_labels_between_p (p
, insn
)
775 && ! reg_referenced_between_p (temp1
, p
, NEXT_INSN (temp3
))
776 && ! reg_set_between_p (temp1
, p
, temp3
)
777 && (GET_CODE (SET_SRC (PATTERN (temp2
))) == CONST_INT
778 || ! reg_set_between_p (SET_SRC (PATTERN (temp2
)),
781 reorder_insns_with_line_notes (temp2
, temp2
, p
);
783 /* Set NEXT to an insn that we know won't go away. */
784 next
= next_active_insn (insn
);
786 /* Delete the jump around the set. Note that we must do
787 this before we redirect the test jumps so that it won't
788 delete the code immediately following the assignment
789 we moved (which might be a jump). */
793 /* We either have two consecutive labels or a jump to
794 a jump, so adjust all the JUMP_INSNs to branch to where
796 for (p
= NEXT_INSN (p
); p
!= next
; p
= NEXT_INSN (p
))
797 if (GET_CODE (p
) == JUMP_INSN
)
798 redirect_jump (p
, target
);
805 /* If we have x = a; if (...) x = b;
806 and either A or B is zero, or if we have if (...) x = 0;
807 and jumps are expensive, try to use a store-flag insn to
808 avoid the jump. (If the jump would be faster, the machine
809 should not have defined the scc insns!). These cases are often
810 made by the previous optimization.
812 INSN here is the jump around the store. We set:
814 TEMP to the "x = b;" insn.
816 TEMP2 to B (const0_rtx in the second case).
817 TEMP3 to A (X in the second case).
818 TEMP4 to the condition being tested.
819 TEMP5 to the earliest insn used to find the condition. */
821 if (/* We can't do this after reload has completed. */
823 && this_is_condjump
&& ! this_is_simplejump
824 /* Set TEMP to the "x = b;" insn. */
825 && (temp
= next_nonnote_insn (insn
)) != 0
826 && GET_CODE (temp
) == INSN
827 && GET_CODE (PATTERN (temp
)) == SET
828 && GET_CODE (temp1
= SET_DEST (PATTERN (temp
))) == REG
829 #ifdef SMALL_REGISTER_CLASSES
830 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
832 && GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
833 && (GET_CODE (temp2
= SET_SRC (PATTERN (temp
))) == REG
834 || GET_CODE (temp2
) == CONST_INT
)
835 /* Allow either form, but prefer the former if both apply. */
836 && (((temp3
= reg_set_last (temp1
, insn
)) != 0
837 && ((GET_CODE (temp3
) == REG
838 #ifdef SMALL_REGISTER_CLASSES
839 && REGNO (temp3
) >= FIRST_PSEUDO_REGISTER
842 || GET_CODE (temp3
) == CONST_INT
))
843 /* Make the latter case look like x = x; if (...) x = 0; */
844 || ((temp3
= temp1
, BRANCH_COST
> 1)
845 && temp2
== const0_rtx
))
846 /* INSN must either branch to the insn after TEMP or the insn
847 after TEMP must branch to the same place as INSN. */
848 && (reallabelprev
== temp
849 || ((temp4
= next_active_insn (temp
)) != 0
850 && simplejump_p (temp4
)
851 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
852 && (temp4
= get_condition (insn
, &temp5
)) != 0
854 /* If B is zero, OK; if A is zero, can only do this if we
855 can reverse the condition. */
856 && (temp2
== const0_rtx
857 || (temp3
== const0_rtx
858 && (can_reverse_comparison_p (temp4
, insn
)))))
860 enum rtx_code code
= GET_CODE (temp4
);
861 rtx yes
= temp3
, var
= temp1
;
865 /* If necessary, reverse the condition. */
866 if (temp3
== const0_rtx
)
867 code
= reverse_condition (code
), yes
= temp2
;
869 /* See if we can do this with a store-flag insn. */
872 /* If YES is the constant 1, it is best to just compute
873 the result directly. If YES is constant and STORE_FLAG_VALUE
874 includes all of its bits, it is best to compute the flag
875 value unnormalized and `and' it with YES. Otherwise,
876 normalize to -1 and `and' with YES. */
877 normalizep
= (yes
== const1_rtx
? 1
878 : (GET_CODE (yes
) == CONST_INT
879 && (INTVAL (yes
) & ~ STORE_FLAG_VALUE
) == 0) ? 0
882 /* We will be putting the store-flag insn immediately in
883 front of the comparison that was originally being done,
884 so we know all the variables in TEMP4 will be valid.
885 However, this might be in front of the assignment of
886 A to VAR. If it is, it would clobber the store-flag
889 Therefore, emit into a temporary which will be copied to
890 VAR immediately after TEMP. */
892 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
893 XEXP (temp4
, 0), XEXP (temp4
, 1),
895 (code
== LTU
|| code
== LEU
896 || code
== GEU
|| code
== GTU
),
903 target
= expand_and (yes
, target
,
904 (GET_CODE (target
) == REG
906 seq
= gen_sequence ();
908 emit_insn_before (seq
, temp5
);
909 emit_insn_after (gen_move_insn (var
, target
), insn
);
911 next
= NEXT_INSN (insn
);
913 delete_insn (prev_nonnote_insn (insn
));
923 /* If branches are expensive, convert
924 if (foo) bar++; to bar += (foo != 0);
925 and similarly for "bar--;"
927 INSN is the conditional branch around the arithmetic. We set:
929 TEMP is the arithmetic insn.
930 TEMP1 is the SET doing the arithmetic.
931 TEMP2 is the operand being incremented or decremented.
932 TEMP3 to the condition being tested.
933 TEMP4 to the earliest insn used to find the condition. */
936 && ! reload_completed
937 && this_is_condjump
&& ! this_is_simplejump
938 && (temp
= next_nonnote_insn (insn
)) != 0
939 && (temp1
= single_set (temp
)) != 0
940 && (temp2
= SET_DEST (temp1
),
941 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
942 && GET_CODE (SET_SRC (temp1
)) == PLUS
943 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
944 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
945 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
946 /* INSN must either branch to the insn after TEMP or the insn
947 after TEMP must branch to the same place as INSN. */
948 && (reallabelprev
== temp
949 || ((temp3
= next_active_insn (temp
)) != 0
950 && simplejump_p (temp3
)
951 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
952 && (temp3
= get_condition (insn
, &temp4
)) != 0
953 && can_reverse_comparison_p (temp3
, insn
))
955 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
956 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
960 /* It must be the case that TEMP2 is not modified in the range
961 [TEMP4, INSN). The one exception we make is if the insn
962 before INSN sets TEMP2 to something which is also unchanged
963 in that range. In that case, we can move the initialization
964 into our sequence. */
966 if ((temp5
= prev_active_insn (insn
)) != 0
967 && GET_CODE (temp5
) == INSN
968 && (temp6
= single_set (temp5
)) != 0
969 && rtx_equal_p (temp2
, SET_DEST (temp6
))
970 && (CONSTANT_P (SET_SRC (temp6
))
971 || GET_CODE (SET_SRC (temp6
)) == REG
972 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
974 emit_insn (PATTERN (temp5
));
976 init
= SET_SRC (temp6
);
979 if (CONSTANT_P (init
)
980 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
981 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
982 XEXP (temp3
, 0), XEXP (temp3
, 1),
984 (code
== LTU
|| code
== LEU
985 || code
== GTU
|| code
== GEU
), 1);
987 /* If we can do the store-flag, do the addition or
991 target
= expand_binop (GET_MODE (temp2
),
992 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
993 ? add_optab
: sub_optab
),
994 temp2
, target
, temp2
, OPTAB_WIDEN
);
998 /* Put the result back in temp2 in case it isn't already.
999 Then replace the jump, possible a CC0-setting insn in
1000 front of the jump, and TEMP, with the sequence we have
1003 if (target
!= temp2
)
1004 emit_move_insn (temp2
, target
);
1009 emit_insns_before (seq
, temp4
);
1013 delete_insn (init_insn
);
1015 next
= NEXT_INSN (insn
);
1017 delete_insn (prev_nonnote_insn (insn
));
1027 /* Simplify if (...) x = 1; else {...} if (x) ...
1028 We recognize this case scanning backwards as well.
1030 TEMP is the assignment to x;
1031 TEMP1 is the label at the head of the second if. */
1032 /* ?? This should call get_condition to find the values being
1033 compared, instead of looking for a COMPARE insn when HAVE_cc0
1034 is not defined. This would allow it to work on the m88k. */
1035 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1036 is not defined and the condition is tested by a separate compare
1037 insn. This is because the code below assumes that the result
1038 of the compare dies in the following branch.
1040 Not only that, but there might be other insns between the
1041 compare and branch whose results are live. Those insns need
1044 A way to fix this is to move the insns at JUMP_LABEL (insn)
1045 to before INSN. If we are running before flow, they will
1046 be deleted if they aren't needed. But this doesn't work
1049 This is really a special-case of jump threading, anyway. The
1050 right thing to do is to replace this and jump threading with
1051 much simpler code in cse.
1053 This code has been turned off in the non-cc0 case in the
1057 else if (this_is_simplejump
1058 /* Safe to skip USE and CLOBBER insns here
1059 since they will not be deleted. */
1060 && (temp
= prev_active_insn (insn
))
1061 && no_labels_between_p (temp
, insn
)
1062 && GET_CODE (temp
) == INSN
1063 && GET_CODE (PATTERN (temp
)) == SET
1064 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1065 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1066 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1067 /* If we find that the next value tested is `x'
1068 (TEMP1 is the insn where this happens), win. */
1069 && GET_CODE (temp1
) == INSN
1070 && GET_CODE (PATTERN (temp1
)) == SET
1072 /* Does temp1 `tst' the value of x? */
1073 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1074 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1075 && (temp1
= next_nonnote_insn (temp1
))
1077 /* Does temp1 compare the value of x against zero? */
1078 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1079 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1080 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1081 == SET_DEST (PATTERN (temp
)))
1082 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1083 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1085 && condjump_p (temp1
))
1087 /* Get the if_then_else from the condjump. */
1088 rtx choice
= SET_SRC (PATTERN (temp1
));
1089 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1091 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1092 rtx val
= SET_SRC (PATTERN (temp
));
1094 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1098 if (cond
== const_true_rtx
)
1099 ultimate
= XEXP (choice
, 1);
1100 else if (cond
== const0_rtx
)
1101 ultimate
= XEXP (choice
, 2);
1105 if (ultimate
== pc_rtx
)
1106 ultimate
= get_label_after (temp1
);
1107 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1108 ultimate
= XEXP (ultimate
, 0);
1111 changed
|= redirect_jump (insn
, ultimate
);
1117 /* @@ This needs a bit of work before it will be right.
1119 Any type of comparison can be accepted for the first and
1120 second compare. When rewriting the first jump, we must
1121 compute the what conditions can reach label3, and use the
1122 appropriate code. We can not simply reverse/swap the code
1123 of the first jump. In some cases, the second jump must be
1127 < == converts to > ==
1128 < != converts to == >
1131 If the code is written to only accept an '==' test for the second
1132 compare, then all that needs to be done is to swap the condition
1133 of the first branch.
1135 It is questionable whether we want this optimization anyways,
1136 since if the user wrote code like this because he/she knew that
1137 the jump to label1 is taken most of the time, then rewriting
1138 this gives slower code. */
1139 /* @@ This should call get_condition to find the values being
1140 compared, instead of looking for a COMPARE insn when HAVE_cc0
1141 is not defined. This would allow it to work on the m88k. */
1142 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1143 is not defined and the condition is tested by a separate compare
1144 insn. This is because the code below assumes that the result
1145 of the compare dies in the following branch. */
1147 /* Simplify test a ~= b
1161 where ~= is an inequality, e.g. >, and ~~= is the swapped
1164 We recognize this case scanning backwards.
1166 TEMP is the conditional jump to `label2';
1167 TEMP1 is the test for `a == b';
1168 TEMP2 is the conditional jump to `label1';
1169 TEMP3 is the test for `a ~= b'. */
1170 else if (this_is_simplejump
1171 && (temp
= prev_active_insn (insn
))
1172 && no_labels_between_p (temp
, insn
)
1173 && condjump_p (temp
)
1174 && (temp1
= prev_active_insn (temp
))
1175 && no_labels_between_p (temp1
, temp
)
1176 && GET_CODE (temp1
) == INSN
1177 && GET_CODE (PATTERN (temp1
)) == SET
1179 && sets_cc0_p (PATTERN (temp1
)) == 1
1181 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1182 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1183 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1185 && (temp2
= prev_active_insn (temp1
))
1186 && no_labels_between_p (temp2
, temp1
)
1187 && condjump_p (temp2
)
1188 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1189 && (temp3
= prev_active_insn (temp2
))
1190 && no_labels_between_p (temp3
, temp2
)
1191 && GET_CODE (PATTERN (temp3
)) == SET
1192 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1193 SET_DEST (PATTERN (temp1
)))
1194 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1195 SET_SRC (PATTERN (temp3
)))
1196 && ! inequality_comparisons_p (PATTERN (temp
))
1197 && inequality_comparisons_p (PATTERN (temp2
)))
1199 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1201 ++LABEL_NUSES (fallthrough_label
);
1202 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1208 if (--LABEL_NUSES (fallthrough_label
) == 0)
1209 delete_insn (fallthrough_label
);
1212 /* Simplify if (...) {... x = 1;} if (x) ...
1214 We recognize this case backwards.
1216 TEMP is the test of `x';
1217 TEMP1 is the assignment to `x' at the end of the
1218 previous statement. */
1219 /* @@ This should call get_condition to find the values being
1220 compared, instead of looking for a COMPARE insn when HAVE_cc0
1221 is not defined. This would allow it to work on the m88k. */
1222 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1223 is not defined and the condition is tested by a separate compare
1224 insn. This is because the code below assumes that the result
1225 of the compare dies in the following branch. */
1227 /* ??? This has to be turned off. The problem is that the
1228 unconditional jump might indirectly end up branching to the
1229 label between TEMP1 and TEMP. We can't detect this, in general,
1230 since it may become a jump to there after further optimizations.
1231 If that jump is done, it will be deleted, so we will retry
1232 this optimization in the next pass, thus an infinite loop.
1234 The present code prevents this by putting the jump after the
1235 label, but this is not logically correct. */
1237 else if (this_is_condjump
1238 /* Safe to skip USE and CLOBBER insns here
1239 since they will not be deleted. */
1240 && (temp
= prev_active_insn (insn
))
1241 && no_labels_between_p (temp
, insn
)
1242 && GET_CODE (temp
) == INSN
1243 && GET_CODE (PATTERN (temp
)) == SET
1245 && sets_cc0_p (PATTERN (temp
)) == 1
1246 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1248 /* Temp must be a compare insn, we can not accept a register
1249 to register move here, since it may not be simply a
1251 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1252 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1253 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1254 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1255 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1257 /* May skip USE or CLOBBER insns here
1258 for checking for opportunity, since we
1259 take care of them later. */
1260 && (temp1
= prev_active_insn (temp
))
1261 && GET_CODE (temp1
) == INSN
1262 && GET_CODE (PATTERN (temp1
)) == SET
1264 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1266 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1267 == SET_DEST (PATTERN (temp1
)))
1269 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1270 /* If this isn't true, cse will do the job. */
1271 && ! no_labels_between_p (temp1
, temp
))
1273 /* Get the if_then_else from the condjump. */
1274 rtx choice
= SET_SRC (PATTERN (insn
));
1275 if (GET_CODE (choice
) == IF_THEN_ELSE
1276 && (GET_CODE (XEXP (choice
, 0)) == EQ
1277 || GET_CODE (XEXP (choice
, 0)) == NE
))
1279 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1284 /* Get the place that condjump will jump to
1285 if it is reached from here. */
1286 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1288 ultimate
= XEXP (choice
, 1);
1290 ultimate
= XEXP (choice
, 2);
1291 /* Get it as a CODE_LABEL. */
1292 if (ultimate
== pc_rtx
)
1293 ultimate
= get_label_after (insn
);
1295 /* Get the label out of the LABEL_REF. */
1296 ultimate
= XEXP (ultimate
, 0);
1298 /* Insert the jump immediately before TEMP, specifically
1299 after the label that is between TEMP1 and TEMP. */
1300 last_insn
= PREV_INSN (temp
);
1302 /* If we would be branching to the next insn, the jump
1303 would immediately be deleted and the re-inserted in
1304 a subsequent pass over the code. So don't do anything
1306 if (next_active_insn (last_insn
)
1307 != next_active_insn (ultimate
))
1309 emit_barrier_after (last_insn
);
1310 p
= emit_jump_insn_after (gen_jump (ultimate
),
1312 JUMP_LABEL (p
) = ultimate
;
1313 ++LABEL_NUSES (ultimate
);
1314 if (INSN_UID (ultimate
) < max_jump_chain
1315 && INSN_CODE (p
) < max_jump_chain
)
1317 jump_chain
[INSN_UID (p
)]
1318 = jump_chain
[INSN_UID (ultimate
)];
1319 jump_chain
[INSN_UID (ultimate
)] = p
;
1327 /* Detect a conditional jump going to the same place
1328 as an immediately following unconditional jump. */
1329 else if (this_is_condjump
1330 && (temp
= next_active_insn (insn
)) != 0
1331 && simplejump_p (temp
)
1332 && (next_active_insn (JUMP_LABEL (insn
))
1333 == next_active_insn (JUMP_LABEL (temp
))))
1339 /* Detect a conditional jump jumping over an unconditional jump. */
1341 else if (this_is_condjump
&& ! this_is_simplejump
1342 && reallabelprev
!= 0
1343 && GET_CODE (reallabelprev
) == JUMP_INSN
1344 && prev_active_insn (reallabelprev
) == insn
1345 && no_labels_between_p (insn
, reallabelprev
)
1346 && simplejump_p (reallabelprev
))
1348 /* When we invert the unconditional jump, we will be
1349 decrementing the usage count of its old label.
1350 Make sure that we don't delete it now because that
1351 might cause the following code to be deleted. */
1352 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
1353 rtx prev_label
= JUMP_LABEL (insn
);
1355 ++LABEL_NUSES (prev_label
);
1357 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
1359 /* It is very likely that if there are USE insns before
1360 this jump, they hold REG_DEAD notes. These REG_DEAD
1361 notes are no longer valid due to this optimization,
1362 and will cause the life-analysis that following passes
1363 (notably delayed-branch scheduling) to think that
1364 these registers are dead when they are not.
1366 To prevent this trouble, we just remove the USE insns
1367 from the insn chain. */
1369 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
1370 && GET_CODE (PATTERN (prev_uses
)) == USE
)
1372 rtx useless
= prev_uses
;
1373 prev_uses
= prev_nonnote_insn (prev_uses
);
1374 delete_insn (useless
);
1377 delete_insn (reallabelprev
);
1382 /* We can now safely delete the label if it is unreferenced
1383 since the delete_insn above has deleted the BARRIER. */
1384 if (--LABEL_NUSES (prev_label
) == 0)
1385 delete_insn (prev_label
);
1390 /* Detect a jump to a jump. */
1392 nlabel
= follow_jumps (JUMP_LABEL (insn
));
1393 if (nlabel
!= JUMP_LABEL (insn
)
1394 && redirect_jump (insn
, nlabel
))
1400 /* Look for if (foo) bar; else break; */
1401 /* The insns look like this:
1402 insn = condjump label1;
1403 ...range1 (some insns)...
1406 ...range2 (some insns)...
1407 jump somewhere unconditionally
1410 rtx label1
= next_label (insn
);
1411 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1412 /* Don't do this optimization on the first round, so that
1413 jump-around-a-jump gets simplified before we ask here
1414 whether a jump is unconditional.
1416 Also don't do it when we are called after reload since
1417 it will confuse reorg. */
1419 && (reload_completed
? ! flag_delayed_branch
: 1)
1420 /* Make sure INSN is something we can invert. */
1421 && condjump_p (insn
)
1423 && JUMP_LABEL (insn
) == label1
1424 && LABEL_NUSES (label1
) == 1
1425 && GET_CODE (range1end
) == JUMP_INSN
1426 && simplejump_p (range1end
))
1428 rtx label2
= next_label (label1
);
1429 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
1430 if (range1end
!= range2end
1431 && JUMP_LABEL (range1end
) == label2
1432 && GET_CODE (range2end
) == JUMP_INSN
1433 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
1434 /* Invert the jump condition, so we
1435 still execute the same insns in each case. */
1436 && invert_jump (insn
, label1
))
1438 rtx range1beg
= next_active_insn (insn
);
1439 rtx range2beg
= next_active_insn (label1
);
1440 rtx range1after
, range2after
;
1441 rtx range1before
, range2before
;
1443 /* Include in each range any line number before it. */
1444 while (PREV_INSN (range1beg
)
1445 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
1446 && NOTE_LINE_NUMBER (PREV_INSN (range1beg
)) > 0)
1447 range1beg
= PREV_INSN (range1beg
);
1449 while (PREV_INSN (range2beg
)
1450 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
1451 && NOTE_LINE_NUMBER (PREV_INSN (range2beg
)) > 0)
1452 range2beg
= PREV_INSN (range2beg
);
1454 /* Don't move NOTEs for blocks or loops; shift them
1455 outside the ranges, where they'll stay put. */
1456 range1beg
= squeeze_notes (range1beg
, range1end
);
1457 range2beg
= squeeze_notes (range2beg
, range2end
);
1459 /* Get current surrounds of the 2 ranges. */
1460 range1before
= PREV_INSN (range1beg
);
1461 range2before
= PREV_INSN (range2beg
);
1462 range1after
= NEXT_INSN (range1end
);
1463 range2after
= NEXT_INSN (range2end
);
1465 /* Splice range2 where range1 was. */
1466 NEXT_INSN (range1before
) = range2beg
;
1467 PREV_INSN (range2beg
) = range1before
;
1468 NEXT_INSN (range2end
) = range1after
;
1469 PREV_INSN (range1after
) = range2end
;
1470 /* Splice range1 where range2 was. */
1471 NEXT_INSN (range2before
) = range1beg
;
1472 PREV_INSN (range1beg
) = range2before
;
1473 NEXT_INSN (range1end
) = range2after
;
1474 PREV_INSN (range2after
) = range1end
;
1481 /* Now that the jump has been tensioned,
1482 try cross jumping: check for identical code
1483 before the jump and before its target label. */
1485 /* First, cross jumping of conditional jumps: */
1487 if (cross_jump
&& condjump_p (insn
))
1489 rtx newjpos
, newlpos
;
1490 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
1492 /* A conditional jump may be crossjumped
1493 only if the place it jumps to follows
1494 an opposing jump that comes back here. */
1496 if (x
!= 0 && ! jump_back_p (x
, insn
))
1497 /* We have no opposing jump;
1498 cannot cross jump this insn. */
1502 /* TARGET is nonzero if it is ok to cross jump
1503 to code before TARGET. If so, see if matches. */
1505 find_cross_jump (insn
, x
, 2,
1506 &newjpos
, &newlpos
);
1510 do_cross_jump (insn
, newjpos
, newlpos
);
1511 /* Make the old conditional jump
1512 into an unconditional one. */
1513 SET_SRC (PATTERN (insn
))
1514 = gen_rtx (LABEL_REF
, VOIDmode
, JUMP_LABEL (insn
));
1515 INSN_CODE (insn
) = -1;
1516 emit_barrier_after (insn
);
1517 /* Add to jump_chain unless this is a new label
1518 whose UID is too large. */
1519 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
1521 jump_chain
[INSN_UID (insn
)]
1522 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1523 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
1530 /* Cross jumping of unconditional jumps:
1531 a few differences. */
1533 if (cross_jump
&& simplejump_p (insn
))
1535 rtx newjpos
, newlpos
;
1540 /* TARGET is nonzero if it is ok to cross jump
1541 to code before TARGET. If so, see if matches. */
1542 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
1543 &newjpos
, &newlpos
);
1545 /* If cannot cross jump to code before the label,
1546 see if we can cross jump to another jump to
1548 /* Try each other jump to this label. */
1549 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
1550 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1551 target
!= 0 && newjpos
== 0;
1552 target
= jump_chain
[INSN_UID (target
)])
1554 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
1555 /* Ignore TARGET if it's deleted. */
1556 && ! INSN_DELETED_P (target
))
1557 find_cross_jump (insn
, target
, 2,
1558 &newjpos
, &newlpos
);
1562 do_cross_jump (insn
, newjpos
, newlpos
);
1568 /* This code was dead in the previous jump.c! */
1569 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
1571 /* Return insns all "jump to the same place"
1572 so we can cross-jump between any two of them. */
1574 rtx newjpos
, newlpos
, target
;
1578 /* If cannot cross jump to code before the label,
1579 see if we can cross jump to another jump to
1581 /* Try each other jump to this label. */
1582 for (target
= jump_chain
[0];
1583 target
!= 0 && newjpos
== 0;
1584 target
= jump_chain
[INSN_UID (target
)])
1586 && ! INSN_DELETED_P (target
)
1587 && GET_CODE (PATTERN (target
)) == RETURN
)
1588 find_cross_jump (insn
, target
, 2,
1589 &newjpos
, &newlpos
);
1593 do_cross_jump (insn
, newjpos
, newlpos
);
1604 /* Delete extraneous line number notes.
1605 Note that two consecutive notes for different lines are not really
1606 extraneous. There should be some indication where that line belonged,
1607 even if it became empty. */
1612 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
1613 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
1615 /* Delete this note if it is identical to previous note. */
1617 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
1618 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
1628 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1629 If so, delete it, and record that this function can drop off the end. */
1635 /* One label can follow the end-note: the return label. */
1636 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
1637 /* Ordinary insns can follow it if returning a structure. */
1638 || GET_CODE (insn
) == INSN
1639 /* If machine uses explicit RETURN insns, no epilogue,
1640 then one of them follows the note. */
1641 || (GET_CODE (insn
) == JUMP_INSN
1642 && GET_CODE (PATTERN (insn
)) == RETURN
)
1643 /* Other kinds of notes can follow also. */
1644 || (GET_CODE (insn
) == NOTE
1645 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
1646 insn
= PREV_INSN (insn
);
1649 /* Report if control can fall through at the end of the function. */
1650 if (insn
&& GET_CODE (insn
) == NOTE
1651 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
)
1657 /* Show JUMP_CHAIN no longer valid. */
1661 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1662 jump. Assume that this unconditional jump is to the exit test code. If
1663 the code is sufficiently simple, make a copy of it before INSN,
1664 followed by a jump to the exit of the loop. Then delete the unconditional
1667 Note that it is possible we can get confused here if the jump immediately
1668 after the loop start branches outside the loop but within an outer loop.
1669 If we are near the exit of that loop, we will copy its exit test. This
1670 will not generate incorrect code, but could suppress some optimizations.
1671 However, such cases are degenerate loops anyway.
1673 Return 1 if we made the change, else 0.
1675 This is only safe immediately after a regscan pass because it uses the
1676 values of regno_first_uid and regno_last_uid. */
1679 duplicate_loop_exit_test (loop_start
)
1685 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
1687 int max_reg
= max_reg_num ();
1690 /* Scan the exit code. We do not perform this optimization if any insn:
1694 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1695 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1696 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1699 Also, don't do this if the exit code is more than 20 insns. */
1701 for (insn
= exitcode
;
1703 && ! (GET_CODE (insn
) == NOTE
1704 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
1705 insn
= NEXT_INSN (insn
))
1707 switch (GET_CODE (insn
))
1713 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
1714 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
1715 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
1720 if (++num_insns
> 20
1721 || find_reg_note (insn
, REG_RETVAL
, 0)
1722 || find_reg_note (insn
, REG_LIBCALL
, 0))
1728 /* Unless INSN is zero, we can do the optimization. */
1734 /* See if any insn sets a register only used in the loop exit code and
1735 not a user variable. If so, replace it with a new register. */
1736 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
1737 if (GET_CODE (insn
) == INSN
1738 && (set
= single_set (insn
)) != 0
1739 && GET_CODE (SET_DEST (set
)) == REG
1740 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
1741 && regno_first_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
))
1743 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
1744 if (regno_last_uid
[REGNO (SET_DEST (set
))] == INSN_UID (p
))
1749 /* We can do the replacement. Allocate reg_map if this is the
1750 first replacement we found. */
1753 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
1754 bzero (reg_map
, max_reg
* sizeof (rtx
));
1757 REG_LOOP_TEST_P (SET_DEST (set
)) = 1;
1759 reg_map
[REGNO (SET_DEST (set
))]
1760 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
1764 /* Now copy each insn. */
1765 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
1766 switch (GET_CODE (insn
))
1769 copy
= emit_barrier_before (loop_start
);
1772 /* Only copy line-number notes. */
1773 if (NOTE_LINE_NUMBER (insn
) >= 0)
1775 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
1776 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
1781 copy
= emit_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
1783 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
1785 mark_jump_label (PATTERN (copy
), copy
, 0);
1787 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1789 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
1790 if (REG_NOTE_KIND (link
) != REG_LABEL
)
1792 = copy_rtx (gen_rtx (EXPR_LIST
, REG_NOTE_KIND (link
),
1793 XEXP (link
, 0), REG_NOTES (copy
)));
1794 if (reg_map
&& REG_NOTES (copy
))
1795 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
1799 copy
= emit_jump_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
1801 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
1802 mark_jump_label (PATTERN (copy
), copy
, 0);
1803 if (REG_NOTES (insn
))
1805 REG_NOTES (copy
) = copy_rtx (REG_NOTES (insn
));
1807 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
1810 /* If this is a simple jump, add it to the jump chain. */
1812 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
1813 && simplejump_p (copy
))
1815 jump_chain
[INSN_UID (copy
)]
1816 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
1817 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
1825 /* Now clean up by emitting a jump to the end label and deleting the jump
1826 at the start of the loop. */
1827 if (GET_CODE (copy
) != BARRIER
)
1829 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
1831 mark_jump_label (PATTERN (copy
), copy
, 0);
1832 if (INSN_UID (copy
) < max_jump_chain
1833 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
1835 jump_chain
[INSN_UID (copy
)]
1836 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
1837 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
1839 emit_barrier_before (loop_start
);
1842 delete_insn (next_nonnote_insn (loop_start
));
1844 /* Mark the exit code as the virtual top of the converted loop. */
1845 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
1850 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
1851 loop-end notes between START and END out before START. Assume that
1852 END is not such a note. START may be such a note. Returns the value
1853 of the new starting insn, which may be different if the original start
1857 squeeze_notes (start
, end
)
1863 for (insn
= start
; insn
!= end
; insn
= next
)
1865 next
= NEXT_INSN (insn
);
1866 if (GET_CODE (insn
) == NOTE
1867 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
1868 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
1869 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
1870 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
1871 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
1872 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
1878 rtx prev
= PREV_INSN (insn
);
1879 PREV_INSN (insn
) = PREV_INSN (start
);
1880 NEXT_INSN (insn
) = start
;
1881 NEXT_INSN (PREV_INSN (insn
)) = insn
;
1882 PREV_INSN (NEXT_INSN (insn
)) = insn
;
1883 NEXT_INSN (prev
) = next
;
1884 PREV_INSN (next
) = prev
;
1892 /* Compare the instructions before insn E1 with those before E2
1893 to find an opportunity for cross jumping.
1894 (This means detecting identical sequences of insns followed by
1895 jumps to the same place, or followed by a label and a jump
1896 to that label, and replacing one with a jump to the other.)
1898 Assume E1 is a jump that jumps to label E2
1899 (that is not always true but it might as well be).
1900 Find the longest possible equivalent sequences
1901 and store the first insns of those sequences into *F1 and *F2.
1902 Store zero there if no equivalent preceding instructions are found.
1904 We give up if we find a label in stream 1.
1905 Actually we could transfer that label into stream 2. */
1908 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
1913 register rtx i1
= e1
, i2
= e2
;
1914 register rtx p1
, p2
;
1917 rtx last1
= 0, last2
= 0;
1918 rtx afterlast1
= 0, afterlast2
= 0;
1926 i1
= prev_nonnote_insn (i1
);
1928 i2
= PREV_INSN (i2
);
1929 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
1930 i2
= PREV_INSN (i2
);
1935 /* Don't allow the range of insns preceding E1 or E2
1936 to include the other (E2 or E1). */
1937 if (i2
== e1
|| i1
== e2
)
1940 /* If we will get to this code by jumping, those jumps will be
1941 tensioned to go directly to the new label (before I2),
1942 so this cross-jumping won't cost extra. So reduce the minimum. */
1943 if (GET_CODE (i1
) == CODE_LABEL
)
1949 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
1956 /* If cross_jump_death_matters is not 0, the insn's mode
1957 indicates whether or not the insn contains any stack-like
1960 if (cross_jump_death_matters
&& GET_MODE (i1
) == QImode
)
1962 /* If register stack conversion has already been done, then
1963 death notes must also be compared before it is certain that
1964 the two instruction streams match. */
1967 HARD_REG_SET i1_regset
, i2_regset
;
1969 CLEAR_HARD_REG_SET (i1_regset
);
1970 CLEAR_HARD_REG_SET (i2_regset
);
1972 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
1973 if (REG_NOTE_KIND (note
) == REG_DEAD
1974 && STACK_REG_P (XEXP (note
, 0)))
1975 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
1977 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
1978 if (REG_NOTE_KIND (note
) == REG_DEAD
1979 && STACK_REG_P (XEXP (note
, 0)))
1980 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
1982 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
1991 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
1992 || ! rtx_renumbered_equal_p (p1
, p2
))
1994 /* The following code helps take care of G++ cleanups. */
1998 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
1999 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, 0)) != 0
2000 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, 0)) != 0)
2001 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, 0)) != 0
2002 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, 0)) != 0)
2003 /* If the equivalences are not to a constant, they may
2004 reference pseudos that no longer exist, so we can't
2006 && CONSTANT_P (XEXP (equiv1
, 0))
2007 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
2009 rtx s1
= single_set (i1
);
2010 rtx s2
= single_set (i2
);
2011 if (s1
!= 0 && s2
!= 0
2012 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
2014 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
2015 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
2016 if (! rtx_renumbered_equal_p (p1
, p2
))
2018 else if (apply_change_group ())
2023 /* Insns fail to match; cross jumping is limited to the following
2027 /* Don't allow the insn after a compare to be shared by
2028 cross-jumping unless the compare is also shared.
2029 Here, if either of these non-matching insns is a compare,
2030 exclude the following insn from possible cross-jumping. */
2031 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
2032 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
2035 /* If cross-jumping here will feed a jump-around-jump
2036 optimization, this jump won't cost extra, so reduce
2038 if (GET_CODE (i1
) == JUMP_INSN
2040 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
2046 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
2048 /* Ok, this insn is potentially includable in a cross-jump here. */
2049 afterlast1
= last1
, afterlast2
= last2
;
2050 last1
= i1
, last2
= i2
, --minimum
;
2054 /* We have to be careful that we do not cross-jump into the middle of
2055 USE-CALL_INSN-CLOBBER sequence. This sequence is used instead of
2056 putting the USE and CLOBBERs inside the CALL_INSN. The delay slot
2057 scheduler needs to know what registers are used and modified by the
2058 CALL_INSN and needs the adjacent USE and CLOBBERs to do so.
2060 ??? At some point we should probably change this so that these are
2061 part of the CALL_INSN. The way we are doing it now is a kludge that
2062 is now causing trouble. */
2064 if (last1
!= 0 && GET_CODE (last1
) == CALL_INSN
2065 && (prev1
= prev_nonnote_insn (last1
))
2066 && GET_CODE (prev1
) == INSN
2067 && GET_CODE (PATTERN (prev1
)) == USE
)
2069 /* Remove this CALL_INSN from the range we can cross-jump. */
2070 last1
= next_real_insn (last1
);
2071 last2
= next_real_insn (last2
);
2076 /* Skip past CLOBBERS since they may be right after a CALL_INSN. It
2077 isn't worth checking for the CALL_INSN. */
2078 while (last1
!= 0 && GET_CODE (PATTERN (last1
)) == CLOBBER
)
2079 last1
= next_real_insn (last1
), last2
= next_real_insn (last2
);
2081 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
2082 *f1
= last1
, *f2
= last2
;
2086 do_cross_jump (insn
, newjpos
, newlpos
)
2087 rtx insn
, newjpos
, newlpos
;
2089 /* Find an existing label at this point
2090 or make a new one if there is none. */
2091 register rtx label
= get_label_before (newlpos
);
2093 /* Make the same jump insn jump to the new point. */
2094 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2096 /* Remove from jump chain of returns. */
2097 delete_from_jump_chain (insn
);
2098 /* Change the insn. */
2099 PATTERN (insn
) = gen_jump (label
);
2100 INSN_CODE (insn
) = -1;
2101 JUMP_LABEL (insn
) = label
;
2102 LABEL_NUSES (label
)++;
2103 /* Add to new the jump chain. */
2104 if (INSN_UID (label
) < max_jump_chain
2105 && INSN_UID (insn
) < max_jump_chain
)
2107 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
2108 jump_chain
[INSN_UID (label
)] = insn
;
2112 redirect_jump (insn
, label
);
2114 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2115 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2116 the NEWJPOS stream. */
2118 while (newjpos
!= insn
)
2122 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
2123 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
2124 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
2125 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
2126 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
2127 remove_note (newlpos
, lnote
);
2129 delete_insn (newjpos
);
2130 newjpos
= next_real_insn (newjpos
);
2131 newlpos
= next_real_insn (newlpos
);
2135 /* Return the label before INSN, or put a new label there. */
2138 get_label_before (insn
)
2143 /* Find an existing label at this point
2144 or make a new one if there is none. */
2145 label
= prev_nonnote_insn (insn
);
2147 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2149 rtx prev
= PREV_INSN (insn
);
2151 /* Don't put a label between a CALL_INSN and USE insns that precede
2154 if (GET_CODE (insn
) == CALL_INSN
2155 || (GET_CODE (insn
) == INSN
&& GET_CODE (PATTERN (insn
)) == SEQUENCE
2156 && GET_CODE (XVECEXP (PATTERN (insn
), 0, 0)) == CALL_INSN
))
2157 while (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == USE
)
2158 prev
= PREV_INSN (prev
);
2160 label
= gen_label_rtx ();
2161 emit_label_after (label
, prev
);
2162 LABEL_NUSES (label
) = 0;
2167 /* Return the label after INSN, or put a new label there. */
2170 get_label_after (insn
)
2175 /* Find an existing label at this point
2176 or make a new one if there is none. */
2177 label
= next_nonnote_insn (insn
);
2179 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2181 /* Don't put a label between a CALL_INSN and CLOBBER insns
2184 if (GET_CODE (insn
) == CALL_INSN
2185 || (GET_CODE (insn
) == INSN
&& GET_CODE (PATTERN (insn
)) == SEQUENCE
2186 && GET_CODE (XVECEXP (PATTERN (insn
), 0, 0)) == CALL_INSN
))
2187 while (GET_CODE (NEXT_INSN (insn
)) == INSN
2188 && GET_CODE (PATTERN (NEXT_INSN (insn
))) == CLOBBER
)
2189 insn
= NEXT_INSN (insn
);
2191 label
= gen_label_rtx ();
2192 emit_label_after (label
, insn
);
2193 LABEL_NUSES (label
) = 0;
2198 /* Return 1 if INSN is a jump that jumps to right after TARGET
2199 only on the condition that TARGET itself would drop through.
2200 Assumes that TARGET is a conditional jump. */
2203 jump_back_p (insn
, target
)
2207 enum rtx_code codei
, codet
;
2209 if (simplejump_p (insn
) || ! condjump_p (insn
)
2210 || simplejump_p (target
)
2211 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
2214 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
2215 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
2217 codei
= GET_CODE (cinsn
);
2218 codet
= GET_CODE (ctarget
);
2220 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
2222 if (! can_reverse_comparison_p (cinsn
, insn
))
2224 codei
= reverse_condition (codei
);
2227 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
2229 if (! can_reverse_comparison_p (ctarget
, target
))
2231 codet
= reverse_condition (codet
);
2234 return (codei
== codet
2235 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
2236 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
2239 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2240 return non-zero if it is safe to reverse this comparison. It is if our
2241 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2242 this is known to be an integer comparison. */
2245 can_reverse_comparison_p (comparison
, insn
)
2251 /* If this is not actually a comparison, we can't reverse it. */
2252 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
2255 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
2256 /* If this is an NE comparison, it is safe to reverse it to an EQ
2257 comparison and vice versa, even for floating point. If no operands
2258 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2259 always false and NE is always true, so the reversal is also valid. */
2260 || GET_CODE (comparison
) == NE
2261 || GET_CODE (comparison
) == EQ
)
2264 arg0
= XEXP (comparison
, 0);
2266 /* Make sure ARG0 is one of the actual objects being compared. If we
2267 can't do this, we can't be sure the comparison can be reversed.
2269 Handle cc0 and a MODE_CC register. */
2270 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
2276 rtx prev
= prev_nonnote_insn (insn
);
2277 rtx set
= single_set (prev
);
2279 if (set
== 0 || SET_DEST (set
) != arg0
)
2282 arg0
= SET_SRC (set
);
2284 if (GET_CODE (arg0
) == COMPARE
)
2285 arg0
= XEXP (arg0
, 0);
2288 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2289 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2290 return (GET_CODE (arg0
) == CONST_INT
2291 || (GET_MODE (arg0
) != VOIDmode
2292 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
2293 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
2296 /* Given an rtx-code for a comparison, return the code
2297 for the negated comparison.
2298 WATCH OUT! reverse_condition is not safe to use on a jump
2299 that might be acting on the results of an IEEE floating point comparison,
2300 because of the special treatment of non-signaling nans in comparisons.
2301 Use can_reverse_comparison_p to be sure. */
2304 reverse_condition (code
)
2345 /* Similar, but return the code when two operands of a comparison are swapped.
2346 This IS safe for IEEE floating-point. */
2349 swap_condition (code
)
2388 /* Given a comparison CODE, return the corresponding unsigned comparison.
2389 If CODE is an equality comparison or already an unsigned comparison,
2390 CODE is returned. */
2393 unsigned_condition (code
)
2423 /* Similarly, return the signed version of a comparison. */
2426 signed_condition (code
)
2456 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2457 truth of CODE1 implies the truth of CODE2. */
2460 comparison_dominates_p (code1
, code2
)
2461 enum rtx_code code1
, code2
;
2469 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
2497 /* Return 1 if INSN is an unconditional jump and nothing else. */
2503 return (GET_CODE (insn
) == JUMP_INSN
2504 && GET_CODE (PATTERN (insn
)) == SET
2505 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
2506 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
2509 /* Return nonzero if INSN is a (possibly) conditional jump
2510 and nothing more. */
2516 register rtx x
= PATTERN (insn
);
2517 if (GET_CODE (x
) != SET
)
2519 if (GET_CODE (SET_DEST (x
)) != PC
)
2521 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2523 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2525 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2526 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2527 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2529 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2530 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2531 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2536 /* Return 1 if X is an RTX that does nothing but set the condition codes
2537 and CLOBBER or USE registers.
2538 Return -1 if X does explicitly set the condition codes,
2539 but also does other things. */
2546 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
2548 if (GET_CODE (x
) == PARALLEL
)
2552 int other_things
= 0;
2553 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2555 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
2556 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
2558 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
2561 return ! sets_cc0
? 0 : other_things
? -1 : 1;
2569 /* Follow any unconditional jump at LABEL;
2570 return the ultimate label reached by any such chain of jumps.
2571 If LABEL is not followed by a jump, return LABEL.
2572 If the chain loops or we can't find end, return LABEL,
2573 since that tells caller to avoid changing the insn.
2575 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2576 a USE or CLOBBER. */
2579 follow_jumps (label
)
2584 register rtx value
= label
;
2589 && (insn
= next_active_insn (value
)) != 0
2590 && GET_CODE (insn
) == JUMP_INSN
2591 && (JUMP_LABEL (insn
) != 0 || GET_CODE (PATTERN (insn
)) == RETURN
)
2592 && (next
= NEXT_INSN (insn
))
2593 && GET_CODE (next
) == BARRIER
);
2596 /* Don't chain through the insn that jumps into a loop
2597 from outside the loop,
2598 since that would create multiple loop entry jumps
2599 and prevent loop optimization. */
2601 if (!reload_completed
)
2602 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
2603 if (GET_CODE (tem
) == NOTE
2604 && NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
)
2607 /* If we have found a cycle, make the insn jump to itself. */
2608 if (JUMP_LABEL (insn
) == label
)
2610 value
= JUMP_LABEL (insn
);
2617 /* Assuming that field IDX of X is a vector of label_refs,
2618 replace each of them by the ultimate label reached by it.
2619 Return nonzero if a change is made.
2620 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2623 tension_vector_labels (x
, idx
)
2629 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
2631 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
2632 register rtx nlabel
= follow_jumps (olabel
);
2633 if (nlabel
&& nlabel
!= olabel
)
2635 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
2636 ++LABEL_NUSES (nlabel
);
2637 if (--LABEL_NUSES (olabel
) == 0)
2638 delete_insn (olabel
);
2645 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2646 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2647 in INSN, then store one of them in JUMP_LABEL (INSN).
2648 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2649 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2650 Also, when there are consecutive labels, canonicalize on the last of them.
2652 Note that two labels separated by a loop-beginning note
2653 must be kept distinct if we have not yet done loop-optimization,
2654 because the gap between them is where loop-optimize
2655 will want to move invariant code to. CROSS_JUMP tells us
2656 that loop-optimization is done with.
2658 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2659 two labels distinct if they are separated by only USE or CLOBBER insns. */
2662 mark_jump_label (x
, insn
, cross_jump
)
2667 register RTX_CODE code
= GET_CODE (x
);
2685 /* If this is a constant-pool reference, see if it is a label. */
2686 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
2687 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
2688 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
2693 register rtx label
= XEXP (x
, 0);
2695 if (GET_CODE (label
) != CODE_LABEL
)
2697 /* If there are other labels following this one,
2698 replace it with the last of the consecutive labels. */
2699 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
2701 if (GET_CODE (next
) == CODE_LABEL
)
2703 else if (cross_jump
&& GET_CODE (next
) == INSN
2704 && (GET_CODE (PATTERN (next
)) == USE
2705 || GET_CODE (PATTERN (next
)) == CLOBBER
))
2707 else if (GET_CODE (next
) != NOTE
)
2709 else if (! cross_jump
2710 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
2711 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
))
2714 XEXP (x
, 0) = label
;
2715 ++LABEL_NUSES (label
);
2718 if (GET_CODE (insn
) == JUMP_INSN
)
2719 JUMP_LABEL (insn
) = label
;
2720 else if (! find_reg_note (insn
, REG_LABEL
, label
))
2722 rtx next
= next_real_insn (label
);
2723 /* Don't record labels that refer to dispatch tables.
2724 This is not necessary, since the tablejump
2725 references the same label.
2726 And if we did record them, flow.c would make worse code. */
2728 || ! (GET_CODE (next
) == JUMP_INSN
2729 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
2730 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
)))
2731 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_LABEL
, label
,
2738 /* Do walk the labels in a vector, but not the first operand of an
2739 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2743 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
2745 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
2746 mark_jump_label (XVECEXP (x
, eltnum
, i
), 0, cross_jump
);
2751 fmt
= GET_RTX_FORMAT (code
);
2752 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2755 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
2756 else if (fmt
[i
] == 'E')
2759 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2760 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
2765 /* If all INSN does is set the pc, delete it,
2766 and delete the insn that set the condition codes for it
2767 if that's what the previous thing was. */
2773 register rtx x
= PATTERN (insn
);
2776 if (GET_CODE (x
) == SET
2777 && GET_CODE (SET_DEST (x
)) == PC
)
2779 prev
= prev_nonnote_insn (insn
);
2781 /* We assume that at this stage
2782 CC's are always set explicitly
2783 and always immediately before the jump that
2784 will use them. So if the previous insn
2785 exists to set the CC's, delete it
2786 (unless it performs auto-increments, etc.). */
2787 if (prev
&& GET_CODE (prev
) == INSN
2788 && sets_cc0_p (PATTERN (prev
)))
2790 if (sets_cc0_p (PATTERN (prev
)) > 0
2791 && !FIND_REG_INC_NOTE (prev
, 0))
2794 /* Otherwise, show that cc0 won't be used. */
2795 REG_NOTES (prev
) = gen_rtx (EXPR_LIST
, REG_UNUSED
,
2796 cc0_rtx
, REG_NOTES (prev
));
2802 /* If we are running before flow.c, we need do nothing since flow.c
2803 will delete the set of the condition code if it is dead. We also
2804 can't know if the register being used as the condition code is
2805 dead or not at this point.
2807 Otherwise, look at all our REG_DEAD notes. If a previous insn
2808 does nothing other than set a register that dies in this jump,
2809 we can delete the insn. */
2811 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
2815 if (REG_NOTE_KIND (note
) != REG_DEAD
2816 /* Verify that the REG_NOTE has a legal value. */
2817 || GET_CODE (XEXP (note
, 0)) != REG
)
2820 for (our_prev
= prev_nonnote_insn (insn
);
2821 our_prev
&& GET_CODE (our_prev
) == INSN
;
2822 our_prev
= prev_nonnote_insn (our_prev
))
2824 /* If we reach a SEQUENCE, it is too complex to try to
2825 do anything with it, so give up. */
2826 if (GET_CODE (PATTERN (our_prev
)) == SEQUENCE
)
2829 if (GET_CODE (PATTERN (our_prev
)) == USE
2830 && GET_CODE (XEXP (PATTERN (our_prev
), 0)) == INSN
)
2831 /* reorg creates USEs that look like this. We leave them
2832 alone because reorg needs them for its own purposes. */
2835 if (reg_set_p (XEXP (note
, 0), PATTERN (our_prev
)))
2837 if (FIND_REG_INC_NOTE (our_prev
, 0))
2840 if (GET_CODE (PATTERN (our_prev
)) == PARALLEL
)
2842 /* If we find a SET of something else, we can't
2847 for (i
= 0; i
< XVECLEN (PATTERN (our_prev
), 0); i
++)
2849 rtx part
= XVECEXP (PATTERN (our_prev
), 0, i
);
2851 if (GET_CODE (part
) == SET
2852 && SET_DEST (part
) != XEXP (note
, 0))
2856 if (i
== XVECLEN (PATTERN (our_prev
), 0))
2857 delete_insn (our_prev
);
2859 else if (GET_CODE (PATTERN (our_prev
)) == SET
2860 && SET_DEST (PATTERN (our_prev
)) == XEXP (note
, 0))
2861 delete_insn (our_prev
);
2866 /* If OUR_PREV references the register that dies here,
2867 it is an additional use. Hence any prior SET isn't
2869 if (reg_overlap_mentioned_p (XEXP (note
, 0),
2870 PATTERN (our_prev
)))
2876 /* Now delete the jump insn itself. */
2881 /* Delete insn INSN from the chain of insns and update label ref counts.
2882 May delete some following insns as a consequence; may even delete
2883 a label elsewhere and insns that follow it.
2885 Returns the first insn after INSN that was not deleted. */
2891 register rtx next
= NEXT_INSN (insn
);
2892 register rtx prev
= PREV_INSN (insn
);
2894 while (next
&& INSN_DELETED_P (next
))
2895 next
= NEXT_INSN (next
);
2897 /* This insn is already deleted => return first following nondeleted. */
2898 if (INSN_DELETED_P (insn
))
2901 /* Mark this insn as deleted. */
2903 INSN_DELETED_P (insn
) = 1;
2905 /* If this is an unconditional jump, delete it from the jump chain. */
2906 if (simplejump_p (insn
))
2907 delete_from_jump_chain (insn
);
2909 /* If instruction is followed by a barrier,
2910 delete the barrier too. */
2912 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
2914 INSN_DELETED_P (next
) = 1;
2915 next
= NEXT_INSN (next
);
2918 /* Patch out INSN (and the barrier if any) */
2924 NEXT_INSN (prev
) = next
;
2925 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
2926 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
2927 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
2932 PREV_INSN (next
) = prev
;
2933 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
2934 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
2937 if (prev
&& NEXT_INSN (prev
) == 0)
2938 set_last_insn (prev
);
2941 /* If deleting a jump, decrement the count of the label,
2942 and delete the label if it is now unused. */
2944 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
2945 if (--LABEL_NUSES (JUMP_LABEL (insn
)) == 0)
2947 /* This can delete NEXT or PREV,
2948 either directly if NEXT is JUMP_LABEL (INSN),
2949 or indirectly through more levels of jumps. */
2950 delete_insn (JUMP_LABEL (insn
));
2951 /* I feel a little doubtful about this loop,
2952 but I see no clean and sure alternative way
2953 to find the first insn after INSN that is not now deleted.
2954 I hope this works. */
2955 while (next
&& INSN_DELETED_P (next
))
2956 next
= NEXT_INSN (next
);
2960 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
2961 prev
= PREV_INSN (prev
);
2963 /* If INSN was a label and a dispatch table follows it,
2964 delete the dispatch table. The tablejump must have gone already.
2965 It isn't useful to fall through into a table. */
2967 if (GET_CODE (insn
) == CODE_LABEL
2968 && NEXT_INSN (insn
) != 0
2969 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
2970 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
2971 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
2972 next
= delete_insn (NEXT_INSN (insn
));
2974 /* If INSN was a label, delete insns following it if now unreachable. */
2976 if (GET_CODE (insn
) == CODE_LABEL
&& prev
2977 && GET_CODE (prev
) == BARRIER
)
2979 register RTX_CODE code
;
2981 && ((code
= GET_CODE (next
)) == INSN
2982 || code
== JUMP_INSN
|| code
== CALL_INSN
2984 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
2987 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
2988 next
= NEXT_INSN (next
);
2989 /* Keep going past other deleted labels to delete what follows. */
2990 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
2991 next
= NEXT_INSN (next
);
2993 /* Note: if this deletes a jump, it can cause more
2994 deletion of unreachable code, after a different label.
2995 As long as the value from this recursive call is correct,
2996 this invocation functions correctly. */
2997 next
= delete_insn (next
);
3004 /* Advance from INSN till reaching something not deleted
3005 then return that. May return INSN itself. */
3008 next_nondeleted_insn (insn
)
3011 while (INSN_DELETED_P (insn
))
3012 insn
= NEXT_INSN (insn
);
3016 /* Delete a range of insns from FROM to TO, inclusive.
3017 This is for the sake of peephole optimization, so assume
3018 that whatever these insns do will still be done by a new
3019 peephole insn that will replace them. */
3022 delete_for_peephole (from
, to
)
3023 register rtx from
, to
;
3025 register rtx insn
= from
;
3029 register rtx next
= NEXT_INSN (insn
);
3030 register rtx prev
= PREV_INSN (insn
);
3032 if (GET_CODE (insn
) != NOTE
)
3034 INSN_DELETED_P (insn
) = 1;
3036 /* Patch this insn out of the chain. */
3037 /* We don't do this all at once, because we
3038 must preserve all NOTEs. */
3040 NEXT_INSN (prev
) = next
;
3043 PREV_INSN (next
) = prev
;
3051 /* Note that if TO is an unconditional jump
3052 we *do not* delete the BARRIER that follows,
3053 since the peephole that replaces this sequence
3054 is also an unconditional jump in that case. */
3057 /* Invert the condition of the jump JUMP, and make it jump
3058 to label NLABEL instead of where it jumps now. */
3061 invert_jump (jump
, nlabel
)
3064 register rtx olabel
= JUMP_LABEL (jump
);
3066 /* We have to either invert the condition and change the label or
3067 do neither. Either operation could fail. We first try to invert
3068 the jump. If that succeeds, we try changing the label. If that fails,
3069 we invert the jump back to what it was. */
3071 if (! invert_exp (PATTERN (jump
), jump
))
3074 if (redirect_jump (jump
, nlabel
))
3077 if (! invert_exp (PATTERN (jump
), jump
))
3078 /* This should just be putting it back the way it was. */
3084 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3086 Return 1 if we can do so, 0 if we cannot find a way to do so that
3087 matches a pattern. */
3090 invert_exp (x
, insn
)
3094 register RTX_CODE code
;
3098 code
= GET_CODE (x
);
3100 if (code
== IF_THEN_ELSE
)
3102 register rtx comp
= XEXP (x
, 0);
3105 /* We can do this in two ways: The preferable way, which can only
3106 be done if this is not an integer comparison, is to reverse
3107 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3108 of the IF_THEN_ELSE. If we can't do either, fail. */
3110 if (can_reverse_comparison_p (comp
, insn
)
3111 && validate_change (insn
, &XEXP (x
, 0),
3112 gen_rtx (reverse_condition (GET_CODE (comp
)),
3113 GET_MODE (comp
), XEXP (comp
, 0),
3114 XEXP (comp
, 1)), 0))
3118 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
3119 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
3120 return apply_change_group ();
3123 fmt
= GET_RTX_FORMAT (code
);
3124 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3127 if (! invert_exp (XEXP (x
, i
), insn
))
3132 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3133 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
3141 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3142 If the old jump target label is unused as a result,
3143 it and the code following it may be deleted.
3145 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3148 The return value will be 1 if the change was made, 0 if it wasn't (this
3149 can only occur for NLABEL == 0). */
3152 redirect_jump (jump
, nlabel
)
3155 register rtx olabel
= JUMP_LABEL (jump
);
3157 if (nlabel
== olabel
)
3160 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
3163 /* If this is an unconditional branch, delete it from the jump_chain of
3164 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3165 have UID's in range and JUMP_CHAIN is valid). */
3166 if (jump_chain
&& (simplejump_p (jump
)
3167 || GET_CODE (PATTERN (jump
)) == RETURN
))
3169 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
3171 delete_from_jump_chain (jump
);
3172 if (label_index
< max_jump_chain
3173 && INSN_UID (jump
) < max_jump_chain
)
3175 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
3176 jump_chain
[label_index
] = jump
;
3180 JUMP_LABEL (jump
) = nlabel
;
3182 ++LABEL_NUSES (nlabel
);
3184 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
3185 delete_insn (olabel
);
3190 /* Delete the instruction JUMP from any jump chain it might be on. */
3193 delete_from_jump_chain (jump
)
3197 rtx olabel
= JUMP_LABEL (jump
);
3199 /* Handle unconditional jumps. */
3200 if (jump_chain
&& olabel
!= 0
3201 && INSN_UID (olabel
) < max_jump_chain
3202 && simplejump_p (jump
))
3203 index
= INSN_UID (olabel
);
3204 /* Handle return insns. */
3205 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
3209 if (jump_chain
[index
] == jump
)
3210 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
3215 for (insn
= jump_chain
[index
];
3217 insn
= jump_chain
[INSN_UID (insn
)])
3218 if (jump_chain
[INSN_UID (insn
)] == jump
)
3220 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
3226 /* If NLABEL is nonzero, throughout the rtx at LOC,
3227 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3228 zero, alter (RETURN) to (LABEL_REF NLABEL).
3230 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3231 validity with validate_change. Convert (set (pc) (label_ref olabel))
3234 Return 0 if we found a change we would like to make but it is invalid.
3235 Otherwise, return 1. */
3238 redirect_exp (loc
, olabel
, nlabel
, insn
)
3243 register rtx x
= *loc
;
3244 register RTX_CODE code
= GET_CODE (x
);
3248 if (code
== LABEL_REF
)
3250 if (XEXP (x
, 0) == olabel
)
3253 XEXP (x
, 0) = nlabel
;
3255 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3259 else if (code
== RETURN
&& olabel
== 0)
3261 x
= gen_rtx (LABEL_REF
, VOIDmode
, nlabel
);
3262 if (loc
== &PATTERN (insn
))
3263 x
= gen_rtx (SET
, VOIDmode
, pc_rtx
, x
);
3264 return validate_change (insn
, loc
, x
, 0);
3267 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
3268 && GET_CODE (SET_SRC (x
)) == LABEL_REF
3269 && XEXP (SET_SRC (x
), 0) == olabel
)
3270 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3272 fmt
= GET_RTX_FORMAT (code
);
3273 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3276 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
3281 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3282 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
3290 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3292 If the old jump target label (before the dispatch table) becomes unused,
3293 it and the dispatch table may be deleted. In that case, find the insn
3294 before the jump references that label and delete it and logical successors
3298 redirect_tablejump (jump
, nlabel
)
3301 register rtx olabel
= JUMP_LABEL (jump
);
3303 /* Add this jump to the jump_chain of NLABEL. */
3304 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
3305 && INSN_UID (jump
) < max_jump_chain
)
3307 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
3308 jump_chain
[INSN_UID (nlabel
)] = jump
;
3311 PATTERN (jump
) = gen_jump (nlabel
);
3312 JUMP_LABEL (jump
) = nlabel
;
3313 ++LABEL_NUSES (nlabel
);
3314 INSN_CODE (jump
) = -1;
3316 if (--LABEL_NUSES (olabel
) == 0)
3318 delete_labelref_insn (jump
, olabel
, 0);
3319 delete_insn (olabel
);
3323 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3324 If we found one, delete it and then delete this insn if DELETE_THIS is
3325 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3328 delete_labelref_insn (insn
, label
, delete_this
)
3335 if (GET_CODE (insn
) != NOTE
3336 && reg_mentioned_p (label
, PATTERN (insn
)))
3347 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
3348 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
3362 /* Like rtx_equal_p except that it considers two REGs as equal
3363 if they renumber to the same value. */
3366 rtx_renumbered_equal_p (x
, y
)
3370 register RTX_CODE code
= GET_CODE (x
);
3375 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
3376 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
3377 && GET_CODE (SUBREG_REG (y
)) == REG
)))
3381 if (GET_MODE (x
) != GET_MODE (y
))
3384 /* If we haven't done any renumbering, don't
3385 make any assumptions. */
3386 if (reg_renumber
== 0)
3387 return rtx_equal_p (x
, y
);
3391 i
= REGNO (SUBREG_REG (x
));
3392 if (reg_renumber
[i
] >= 0)
3393 i
= reg_renumber
[i
];
3394 i
+= SUBREG_WORD (x
);
3399 if (reg_renumber
[i
] >= 0)
3400 i
= reg_renumber
[i
];
3402 if (GET_CODE (y
) == SUBREG
)
3404 j
= REGNO (SUBREG_REG (y
));
3405 if (reg_renumber
[j
] >= 0)
3406 j
= reg_renumber
[j
];
3407 j
+= SUBREG_WORD (y
);
3412 if (reg_renumber
[j
] >= 0)
3413 j
= reg_renumber
[j
];
3417 /* Now we have disposed of all the cases
3418 in which different rtx codes can match. */
3419 if (code
!= GET_CODE (y
))
3430 return XINT (x
, 0) == XINT (y
, 0);
3433 /* Two label-refs are equivalent if they point at labels
3434 in the same position in the instruction stream. */
3435 return (next_real_insn (XEXP (x
, 0))
3436 == next_real_insn (XEXP (y
, 0)));
3439 return XSTR (x
, 0) == XSTR (y
, 0);
3442 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3444 if (GET_MODE (x
) != GET_MODE (y
))
3447 /* Compare the elements. If any pair of corresponding elements
3448 fail to match, return 0 for the whole things. */
3450 fmt
= GET_RTX_FORMAT (code
);
3451 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3457 if (XINT (x
, i
) != XINT (y
, i
))
3462 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
3467 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
3472 if (XEXP (x
, i
) != XEXP (y
, i
))
3479 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
3481 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
3482 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
3493 /* If X is a hard register or equivalent to one or a subregister of one,
3494 return the hard register number. If X is a pseudo register that was not
3495 assigned a hard register, return the pseudo register number. Otherwise,
3496 return -1. Any rtx is valid for X. */
3502 if (GET_CODE (x
) == REG
)
3504 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
3505 return reg_renumber
[REGNO (x
)];
3508 if (GET_CODE (x
) == SUBREG
)
3510 int base
= true_regnum (SUBREG_REG (x
));
3511 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
3512 return SUBREG_WORD (x
) + base
;
3517 /* Optimize code of the form:
3519 for (x = a[i]; x; ...)
3521 for (x = a[i]; x; ...)
3525 Loop optimize will change the above code into
3529 { ...; if (! (x = ...)) break; }
3532 { ...; if (! (x = ...)) break; }
3535 In general, if the first test fails, the program can branch
3536 directly to `foo' and skip the second try which is doomed to fail.
3537 We run this after loop optimization and before flow analysis. */
3539 /* When comparing the insn patterns, we track the fact that different
3540 pseudo-register numbers may have been used in each computation.
3541 The following array stores an equivalence -- same_regs[I] == J means
3542 that pseudo register I was used in the first set of tests in a context
3543 where J was used in the second set. We also count the number of such
3544 pending equivalences. If nonzero, the expressions really aren't the
3547 static short *same_regs
;
3549 static int num_same_regs
;
3551 /* Track any registers modified between the target of the first jump and
3552 the second jump. They never compare equal. */
3554 static char *modified_regs
;
3556 /* Record if memory was modified. */
3558 static int modified_mem
;
3560 /* Called via note_stores on each insn between the target of the first
3561 branch and the second branch. It marks any changed registers. */
3564 mark_modified_reg (dest
, x
)
3570 if (GET_CODE (dest
) == SUBREG
)
3571 dest
= SUBREG_REG (dest
);
3573 if (GET_CODE (dest
) == MEM
)
3576 if (GET_CODE (dest
) != REG
)
3579 regno
= REGNO (dest
);
3580 if (regno
>= FIRST_PSEUDO_REGISTER
)
3581 modified_regs
[regno
] = 1;
3583 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
3584 modified_regs
[regno
+ i
] = 1;
3587 /* F is the first insn in the chain of insns. */
3590 thread_jumps (f
, max_reg
, verbose
)
3595 /* Basic algorithm is to find a conditional branch,
3596 the label it may branch to, and the branch after
3597 that label. If the two branches test the same condition,
3598 walk back from both branch paths until the insn patterns
3599 differ, or code labels are hit. If we make it back to
3600 the target of the first branch, then we know that the first branch
3601 will either always succeed or always fail depending on the relative
3602 senses of the two branches. So adjust the first branch accordingly
3605 rtx label
, b1
, b2
, t1
, t2
;
3606 enum rtx_code code1
, code2
;
3607 rtx b1op0
, b1op1
, b2op0
, b2op1
;
3612 /* Allocate register tables and quick-reset table. */
3613 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
3614 same_regs
= (short *) alloca (max_reg
* sizeof (short));
3615 all_reset
= (short *) alloca (max_reg
* sizeof (short));
3616 for (i
= 0; i
< max_reg
; i
++)
3623 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
3625 /* Get to a candidate branch insn. */
3626 if (GET_CODE (b1
) != JUMP_INSN
3627 || ! condjump_p (b1
) || simplejump_p (b1
)
3628 || JUMP_LABEL (b1
) == 0)
3631 bzero (modified_regs
, max_reg
* sizeof (char));
3634 bcopy (all_reset
, same_regs
, max_reg
* sizeof (short));
3637 label
= JUMP_LABEL (b1
);
3639 /* Look for a branch after the target. Record any registers and
3640 memory modified between the target and the branch. Stop when we
3641 get to a label since we can't know what was changed there. */
3642 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
3644 if (GET_CODE (b2
) == CODE_LABEL
)
3647 else if (GET_CODE (b2
) == JUMP_INSN
)
3649 /* If this is an unconditional jump and is the only use of
3650 its target label, we can follow it. */
3651 if (simplejump_p (b2
)
3652 && JUMP_LABEL (b2
) != 0
3653 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
3655 b2
= JUMP_LABEL (b2
);
3662 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
3665 if (GET_CODE (b2
) == CALL_INSN
)
3668 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3669 if (call_used_regs
[i
] && ! fixed_regs
[i
]
3670 && i
!= STACK_POINTER_REGNUM
3671 && i
!= FRAME_POINTER_REGNUM
3672 && i
!= ARG_POINTER_REGNUM
)
3673 modified_regs
[i
] = 1;
3676 note_stores (PATTERN (b2
), mark_modified_reg
);
3679 /* Check the next candidate branch insn from the label
3682 || GET_CODE (b2
) != JUMP_INSN
3684 || ! condjump_p (b2
)
3685 || simplejump_p (b2
))
3688 /* Get the comparison codes and operands, reversing the
3689 codes if appropriate. If we don't have comparison codes,
3690 we can't do anything. */
3691 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
3692 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
3693 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
3694 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
3695 code1
= reverse_condition (code1
);
3697 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
3698 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
3699 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
3700 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
3701 code2
= reverse_condition (code2
);
3703 /* If they test the same things and knowing that B1 branches
3704 tells us whether or not B2 branches, check if we
3705 can thread the branch. */
3706 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
3707 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
3708 && (comparison_dominates_p (code1
, code2
)
3709 || comparison_dominates_p (code1
, reverse_condition (code2
))))
3711 t1
= prev_nonnote_insn (b1
);
3712 t2
= prev_nonnote_insn (b2
);
3714 while (t1
!= 0 && t2
!= 0)
3716 if (t1
== 0 || t2
== 0)
3721 /* We have reached the target of the first branch.
3722 If there are no pending register equivalents,
3723 we know that this branch will either always
3724 succeed (if the senses of the two branches are
3725 the same) or always fail (if not). */
3728 if (num_same_regs
!= 0)
3731 if (comparison_dominates_p (code1
, code2
))
3732 new_label
= JUMP_LABEL (b2
);
3734 new_label
= get_label_after (b2
);
3736 if (JUMP_LABEL (b1
) != new_label
3737 && redirect_jump (b1
, new_label
))
3742 /* If either of these is not a normal insn (it might be
3743 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3744 have already been skipped above.) Similarly, fail
3745 if the insns are different. */
3746 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
3747 || recog_memoized (t1
) != recog_memoized (t2
)
3748 || ! rtx_equal_for_thread_p (PATTERN (t1
),
3752 t1
= prev_nonnote_insn (t1
);
3753 t2
= prev_nonnote_insn (t2
);
3760 /* This is like RTX_EQUAL_P except that it knows about our handling of
3761 possibly equivalent registers and knows to consider volatile and
3762 modified objects as not equal.
3764 YINSN is the insn containing Y. */
3767 rtx_equal_for_thread_p (x
, y
, yinsn
)
3773 register enum rtx_code code
;
3776 code
= GET_CODE (x
);
3777 /* Rtx's of different codes cannot be equal. */
3778 if (code
!= GET_CODE (y
))
3781 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
3782 (REG:SI x) and (REG:HI x) are NOT equivalent. */
3784 if (GET_MODE (x
) != GET_MODE (y
))
3787 /* Handle special-cases first. */
3791 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
3794 /* If neither is user variable or hard register, check for possible
3796 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
3797 || REGNO (x
) < FIRST_PSEUDO_REGISTER
3798 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
3801 if (same_regs
[REGNO (x
)] == -1)
3803 same_regs
[REGNO (x
)] = REGNO (y
);
3806 /* If this is the first time we are seeing a register on the `Y'
3807 side, see if it is the last use. If not, we can't thread the
3808 jump, so mark it as not equivalent. */
3809 if (regno_last_uid
[REGNO (y
)] != INSN_UID (yinsn
))
3815 return (same_regs
[REGNO (x
)] == REGNO (y
));
3820 /* If memory modified or either volatile, not equivalent.
3821 Else, check address. */
3822 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
3825 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
3828 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
3834 /* Cancel a pending `same_regs' if setting equivalenced registers.
3835 Then process source. */
3836 if (GET_CODE (SET_DEST (x
)) == REG
3837 && GET_CODE (SET_DEST (y
)) == REG
)
3839 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
3841 same_regs
[REGNO (SET_DEST (x
))] = -1;
3844 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
3848 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
3851 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
3854 return XEXP (x
, 0) == XEXP (y
, 0);
3857 return XSTR (x
, 0) == XSTR (y
, 0);
3863 fmt
= GET_RTX_FORMAT (code
);
3864 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3870 if (XINT (x
, i
) != XINT (y
, i
))
3876 /* Two vectors must have the same length. */
3877 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
3880 /* And the corresponding elements must match. */
3881 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3882 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
3883 XVECEXP (y
, i
, j
), yinsn
) == 0)
3888 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
3894 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
3899 /* These are just backpointers, so they don't matter. */
3905 /* It is believed that rtx's at this level will never
3906 contain anything but integers and other rtx's,
3907 except for within LABEL_REFs and SYMBOL_REFs. */
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