1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91, 92, 93, 1994 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
PROTO((rtx
));
107 static void find_cross_jump
PROTO((rtx
, rtx
, int, rtx
*, rtx
*));
108 static void do_cross_jump
PROTO((rtx
, rtx
, rtx
));
109 static int jump_back_p
PROTO((rtx
, rtx
));
110 static int tension_vector_labels
PROTO((rtx
, int));
111 static void mark_jump_label
PROTO((rtx
, rtx
, int));
112 static void delete_computation
PROTO((rtx
));
113 static void delete_from_jump_chain
PROTO((rtx
));
114 static int delete_labelref_insn
PROTO((rtx
, rtx
, int));
115 static void redirect_tablejump
PROTO((rtx
, rtx
));
117 /* Delete no-op jumps and optimize jumps to jumps
118 and jumps around jumps.
119 Delete unused labels and unreachable code.
121 If CROSS_JUMP is 1, detect matching code
122 before a jump and its destination and unify them.
123 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
125 If NOOP_MOVES is nonzero, delete no-op move insns.
127 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
128 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
130 If `optimize' is zero, don't change any code,
131 just determine whether control drops off the end of the function.
132 This case occurs when we have -W and not -O.
133 It works because `delete_insn' checks the value of `optimize'
134 and refrains from actually deleting when that is 0. */
137 jump_optimize (f
, cross_jump
, noop_moves
, after_regscan
)
143 register rtx insn
, next
, note
;
149 cross_jump_death_matters
= (cross_jump
== 2);
151 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
152 notes whose labels don't occur in the insn any more. */
154 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
156 if (GET_CODE (insn
) == CODE_LABEL
)
157 LABEL_NUSES (insn
) = (LABEL_PRESERVE_P (insn
) != 0);
158 else if (GET_CODE (insn
) == JUMP_INSN
)
159 JUMP_LABEL (insn
) = 0;
160 else if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == CALL_INSN
)
161 for (note
= REG_NOTES (insn
); note
; note
= next
)
163 next
= XEXP (note
, 1);
164 if (REG_NOTE_KIND (note
) == REG_LABEL
165 && ! reg_mentioned_p (XEXP (note
, 0), PATTERN (insn
)))
166 remove_note (insn
, note
);
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 ((char *) 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_RTX_CLASS (GET_CODE (insn
)) == 'i'
211 && ! INSN_DELETED_P (insn
))
213 mark_jump_label (PATTERN (insn
), insn
, cross_jump
);
214 if (GET_CODE (insn
) == JUMP_INSN
)
216 if (JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
218 jump_chain
[INSN_UID (insn
)]
219 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
220 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
222 if (GET_CODE (PATTERN (insn
)) == RETURN
)
224 jump_chain
[INSN_UID (insn
)] = jump_chain
[0];
225 jump_chain
[0] = insn
;
230 /* Keep track of labels used from static data;
231 they cannot ever be deleted. */
233 for (insn
= forced_labels
; insn
; insn
= XEXP (insn
, 1))
234 LABEL_NUSES (XEXP (insn
, 0))++;
236 /* Delete all labels already not referenced.
237 Also find the last insn. */
240 for (insn
= f
; insn
; )
242 if (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NUSES (insn
) == 0)
243 insn
= delete_insn (insn
);
247 insn
= NEXT_INSN (insn
);
253 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
254 If so record that this function can drop off the end. */
260 /* One label can follow the end-note: the return label. */
261 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
262 /* Ordinary insns can follow it if returning a structure. */
263 || GET_CODE (insn
) == INSN
264 /* If machine uses explicit RETURN insns, no epilogue,
265 then one of them follows the note. */
266 || (GET_CODE (insn
) == JUMP_INSN
267 && GET_CODE (PATTERN (insn
)) == RETURN
)
268 /* Other kinds of notes can follow also. */
269 || (GET_CODE (insn
) == NOTE
270 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
271 insn
= PREV_INSN (insn
);
274 /* Report if control can fall through at the end of the function. */
275 if (insn
&& GET_CODE (insn
) == NOTE
276 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
277 && ! INSN_DELETED_P (insn
))
280 /* Zero the "deleted" flag of all the "deleted" insns. */
281 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
282 INSN_DELETED_P (insn
) = 0;
289 /* If we fall through to the epilogue, see if we can insert a RETURN insn
290 in front of it. If the machine allows it at this point (we might be
291 after reload for a leaf routine), it will improve optimization for it
293 insn
= get_last_insn ();
294 while (insn
&& GET_CODE (insn
) == NOTE
)
295 insn
= PREV_INSN (insn
);
297 if (insn
&& GET_CODE (insn
) != BARRIER
)
299 emit_jump_insn (gen_return ());
306 for (insn
= f
; insn
; )
308 next
= NEXT_INSN (insn
);
310 if (GET_CODE (insn
) == INSN
)
312 register rtx body
= PATTERN (insn
);
314 /* Combine stack_adjusts with following push_insns. */
316 if (GET_CODE (body
) == SET
317 && SET_DEST (body
) == stack_pointer_rtx
318 && GET_CODE (SET_SRC (body
)) == PLUS
319 && XEXP (SET_SRC (body
), 0) == stack_pointer_rtx
320 && GET_CODE (XEXP (SET_SRC (body
), 1)) == CONST_INT
321 && INTVAL (XEXP (SET_SRC (body
), 1)) > 0)
324 rtx stack_adjust_insn
= insn
;
325 int stack_adjust_amount
= INTVAL (XEXP (SET_SRC (body
), 1));
326 int total_pushed
= 0;
329 /* Find all successive push insns. */
331 /* Don't convert more than three pushes;
332 that starts adding too many displaced addresses
333 and the whole thing starts becoming a losing
338 p
= next_nonnote_insn (p
);
339 if (p
== 0 || GET_CODE (p
) != INSN
)
342 if (GET_CODE (pbody
) != SET
)
344 dest
= SET_DEST (pbody
);
345 /* Allow a no-op move between the adjust and the push. */
346 if (GET_CODE (dest
) == REG
347 && GET_CODE (SET_SRC (pbody
)) == REG
348 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
350 if (! (GET_CODE (dest
) == MEM
351 && GET_CODE (XEXP (dest
, 0)) == POST_INC
352 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
355 if (total_pushed
+ GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)))
356 > stack_adjust_amount
)
358 total_pushed
+= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
361 /* Discard the amount pushed from the stack adjust;
362 maybe eliminate it entirely. */
363 if (total_pushed
>= stack_adjust_amount
)
365 delete_computation (stack_adjust_insn
);
366 total_pushed
= stack_adjust_amount
;
369 XEXP (SET_SRC (PATTERN (stack_adjust_insn
)), 1)
370 = GEN_INT (stack_adjust_amount
- total_pushed
);
372 /* Change the appropriate push insns to ordinary stores. */
374 while (total_pushed
> 0)
377 p
= next_nonnote_insn (p
);
378 if (GET_CODE (p
) != INSN
)
381 if (GET_CODE (pbody
) == SET
)
383 dest
= SET_DEST (pbody
);
384 if (! (GET_CODE (dest
) == MEM
385 && GET_CODE (XEXP (dest
, 0)) == POST_INC
386 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
388 total_pushed
-= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
389 /* If this push doesn't fully fit in the space
390 of the stack adjust that we deleted,
391 make another stack adjust here for what we
392 didn't use up. There should be peepholes
393 to recognize the resulting sequence of insns. */
394 if (total_pushed
< 0)
396 emit_insn_before (gen_add2_insn (stack_pointer_rtx
,
397 GEN_INT (- total_pushed
)),
402 = plus_constant (stack_pointer_rtx
, total_pushed
);
407 /* Detect and delete no-op move instructions
408 resulting from not allocating a parameter in a register. */
410 if (GET_CODE (body
) == SET
411 && (SET_DEST (body
) == SET_SRC (body
)
412 || (GET_CODE (SET_DEST (body
)) == MEM
413 && GET_CODE (SET_SRC (body
)) == MEM
414 && rtx_equal_p (SET_SRC (body
), SET_DEST (body
))))
415 && ! (GET_CODE (SET_DEST (body
)) == MEM
416 && MEM_VOLATILE_P (SET_DEST (body
)))
417 && ! (GET_CODE (SET_SRC (body
)) == MEM
418 && MEM_VOLATILE_P (SET_SRC (body
))))
419 delete_computation (insn
);
421 /* Detect and ignore no-op move instructions
422 resulting from smart or fortuitous register allocation. */
424 else if (GET_CODE (body
) == SET
)
426 int sreg
= true_regnum (SET_SRC (body
));
427 int dreg
= true_regnum (SET_DEST (body
));
429 if (sreg
== dreg
&& sreg
>= 0)
431 else if (sreg
>= 0 && dreg
>= 0)
434 rtx tem
= find_equiv_reg (NULL_RTX
, insn
, 0,
435 sreg
, NULL_PTR
, dreg
,
436 GET_MODE (SET_SRC (body
)));
438 #ifdef PRESERVE_DEATH_INFO_REGNO_P
439 /* Deleting insn could lose a death-note for SREG or DREG
440 so don't do it if final needs accurate death-notes. */
441 if (! PRESERVE_DEATH_INFO_REGNO_P (sreg
)
442 && ! PRESERVE_DEATH_INFO_REGNO_P (dreg
))
445 /* DREG may have been the target of a REG_DEAD note in
446 the insn which makes INSN redundant. If so, reorg
447 would still think it is dead. So search for such a
448 note and delete it if we find it. */
449 for (trial
= prev_nonnote_insn (insn
);
450 trial
&& GET_CODE (trial
) != CODE_LABEL
;
451 trial
= prev_nonnote_insn (trial
))
452 if (find_regno_note (trial
, REG_DEAD
, dreg
))
454 remove_death (dreg
, trial
);
459 && GET_MODE (tem
) == GET_MODE (SET_DEST (body
)))
463 else if (dreg
>= 0 && CONSTANT_P (SET_SRC (body
))
464 && find_equiv_reg (SET_SRC (body
), insn
, 0, dreg
,
466 GET_MODE (SET_DEST (body
))))
468 /* This handles the case where we have two consecutive
469 assignments of the same constant to pseudos that didn't
470 get a hard reg. Each SET from the constant will be
471 converted into a SET of the spill register and an
472 output reload will be made following it. This produces
473 two loads of the same constant into the same spill
478 /* Look back for a death note for the first reg.
479 If there is one, it is no longer accurate. */
480 while (in_insn
&& GET_CODE (in_insn
) != CODE_LABEL
)
482 if ((GET_CODE (in_insn
) == INSN
483 || GET_CODE (in_insn
) == JUMP_INSN
)
484 && find_regno_note (in_insn
, REG_DEAD
, dreg
))
486 remove_death (dreg
, in_insn
);
489 in_insn
= PREV_INSN (in_insn
);
492 /* Delete the second load of the value. */
496 else if (GET_CODE (body
) == PARALLEL
)
498 /* If each part is a set between two identical registers or
499 a USE or CLOBBER, delete the insn. */
503 for (i
= XVECLEN (body
, 0) - 1; i
>= 0; i
--)
505 tem
= XVECEXP (body
, 0, i
);
506 if (GET_CODE (tem
) == USE
|| GET_CODE (tem
) == CLOBBER
)
509 if (GET_CODE (tem
) != SET
510 || (sreg
= true_regnum (SET_SRC (tem
))) < 0
511 || (dreg
= true_regnum (SET_DEST (tem
))) < 0
519 #if !BYTES_BIG_ENDIAN /* Not worth the hair to detect this
520 in the big-endian case. */
521 /* Also delete insns to store bit fields if they are no-ops. */
522 else if (GET_CODE (body
) == SET
523 && GET_CODE (SET_DEST (body
)) == ZERO_EXTRACT
524 && XEXP (SET_DEST (body
), 2) == const0_rtx
525 && XEXP (SET_DEST (body
), 0) == SET_SRC (body
)
526 && ! (GET_CODE (SET_SRC (body
)) == MEM
527 && MEM_VOLATILE_P (SET_SRC (body
))))
529 #endif /* not BYTES_BIG_ENDIAN */
534 /* If we haven't yet gotten to reload and we have just run regscan,
535 delete any insn that sets a register that isn't used elsewhere.
536 This helps some of the optimizations below by having less insns
537 being jumped around. */
539 if (! reload_completed
&& after_regscan
)
540 for (insn
= f
; insn
; insn
= next
)
542 rtx set
= single_set (insn
);
544 next
= NEXT_INSN (insn
);
546 if (set
&& GET_CODE (SET_DEST (set
)) == REG
547 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
548 && regno_first_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
)
549 /* We use regno_last_note_uid so as not to delete the setting
550 of a reg that's used in notes. A subsequent optimization
551 might arrange to use that reg for real. */
552 && regno_last_note_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
)
553 && ! side_effects_p (SET_SRC (set
))
554 && ! find_reg_note (insn
, REG_RETVAL
, 0))
558 /* Now iterate optimizing jumps until nothing changes over one pass. */
564 for (insn
= f
; insn
; insn
= next
)
567 rtx temp
, temp1
, temp2
, temp3
, temp4
, temp5
, temp6
;
569 int this_is_simplejump
, this_is_condjump
, reversep
;
570 int this_is_condjump_in_parallel
;
572 /* If NOT the first iteration, if this is the last jump pass
573 (just before final), do the special peephole optimizations.
574 Avoiding the first iteration gives ordinary jump opts
575 a chance to work before peephole opts. */
577 if (reload_completed
&& !first
&& !flag_no_peephole
)
578 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
582 /* That could have deleted some insns after INSN, so check now
583 what the following insn is. */
585 next
= NEXT_INSN (insn
);
587 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
588 jump. Try to optimize by duplicating the loop exit test if so.
589 This is only safe immediately after regscan, because it uses
590 the values of regno_first_uid and regno_last_uid. */
591 if (after_regscan
&& GET_CODE (insn
) == NOTE
592 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
593 && (temp1
= next_nonnote_insn (insn
)) != 0
594 && simplejump_p (temp1
))
596 temp
= PREV_INSN (insn
);
597 if (duplicate_loop_exit_test (insn
))
600 next
= NEXT_INSN (temp
);
605 if (GET_CODE (insn
) != JUMP_INSN
)
608 this_is_simplejump
= simplejump_p (insn
);
609 this_is_condjump
= condjump_p (insn
);
610 this_is_condjump_in_parallel
= condjump_in_parallel_p (insn
);
612 /* Tension the labels in dispatch tables. */
614 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
615 changed
|= tension_vector_labels (PATTERN (insn
), 0);
616 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
617 changed
|= tension_vector_labels (PATTERN (insn
), 1);
619 /* If a dispatch table always goes to the same place,
620 get rid of it and replace the insn that uses it. */
622 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
623 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
626 rtx pat
= PATTERN (insn
);
627 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
628 int len
= XVECLEN (pat
, diff_vec_p
);
629 rtx dispatch
= prev_real_insn (insn
);
631 for (i
= 0; i
< len
; i
++)
632 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
633 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
637 && GET_CODE (dispatch
) == JUMP_INSN
638 && JUMP_LABEL (dispatch
) != 0
639 /* Don't mess with a casesi insn. */
640 && !(GET_CODE (PATTERN (dispatch
)) == SET
641 && (GET_CODE (SET_SRC (PATTERN (dispatch
)))
643 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
645 redirect_tablejump (dispatch
,
646 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
651 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
653 /* If a jump references the end of the function, try to turn
654 it into a RETURN insn, possibly a conditional one. */
655 if (JUMP_LABEL (insn
)
656 && (next_active_insn (JUMP_LABEL (insn
)) == 0
657 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn
))))
659 changed
|= redirect_jump (insn
, NULL_RTX
);
661 /* Detect jump to following insn. */
662 if (reallabelprev
== insn
&& condjump_p (insn
))
669 /* If we have an unconditional jump preceded by a USE, try to put
670 the USE before the target and jump there. This simplifies many
671 of the optimizations below since we don't have to worry about
672 dealing with these USE insns. We only do this if the label
673 being branch to already has the identical USE or if code
674 never falls through to that label. */
676 if (this_is_simplejump
677 && (temp
= prev_nonnote_insn (insn
)) != 0
678 && GET_CODE (temp
) == INSN
&& GET_CODE (PATTERN (temp
)) == USE
679 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
680 && (GET_CODE (temp1
) == BARRIER
681 || (GET_CODE (temp1
) == INSN
682 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
)))))
684 if (GET_CODE (temp1
) == BARRIER
)
686 emit_insn_after (PATTERN (temp
), temp1
);
687 temp1
= NEXT_INSN (temp1
);
691 redirect_jump (insn
, get_label_before (temp1
));
692 reallabelprev
= prev_real_insn (temp1
);
696 /* Simplify if (...) x = a; else x = b; by converting it
697 to x = b; if (...) x = a;
698 if B is sufficiently simple, the test doesn't involve X,
699 and nothing in the test modifies B or X.
701 If we have small register classes, we also can't do this if X
704 If the "x = b;" insn has any REG_NOTES, we don't do this because
705 of the possibility that we are running after CSE and there is a
706 REG_EQUAL note that is only valid if the branch has already been
707 taken. If we move the insn with the REG_EQUAL note, we may
708 fold the comparison to always be false in a later CSE pass.
709 (We could also delete the REG_NOTES when moving the insn, but it
710 seems simpler to not move it.) An exception is that we can move
711 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
712 value is the same as "b".
714 INSN is the branch over the `else' part.
718 TEMP to the jump insn preceding "x = a;"
720 TEMP2 to the insn that sets "x = b;"
721 TEMP3 to the insn that sets "x = a;"
722 TEMP4 to the set of "x = b"; */
724 if (this_is_simplejump
725 && (temp3
= prev_active_insn (insn
)) != 0
726 && GET_CODE (temp3
) == INSN
727 && (temp4
= single_set (temp3
)) != 0
728 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
729 #ifdef SMALL_REGISTER_CLASSES
730 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
732 && (temp2
= next_active_insn (insn
)) != 0
733 && GET_CODE (temp2
) == INSN
734 && (temp4
= single_set (temp2
)) != 0
735 && rtx_equal_p (SET_DEST (temp4
), temp1
)
736 && (GET_CODE (SET_SRC (temp4
)) == REG
737 || GET_CODE (SET_SRC (temp4
)) == SUBREG
738 || CONSTANT_P (SET_SRC (temp4
)))
739 && (REG_NOTES (temp2
) == 0
740 || ((REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUAL
741 || REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUIV
)
742 && XEXP (REG_NOTES (temp2
), 1) == 0
743 && rtx_equal_p (XEXP (REG_NOTES (temp2
), 0),
745 && (temp
= prev_active_insn (temp3
)) != 0
746 && condjump_p (temp
) && ! simplejump_p (temp
)
747 /* TEMP must skip over the "x = a;" insn */
748 && prev_real_insn (JUMP_LABEL (temp
)) == insn
749 && no_labels_between_p (insn
, JUMP_LABEL (temp
))
750 /* There must be no other entries to the "x = b;" insn. */
751 && no_labels_between_p (JUMP_LABEL (temp
), temp2
)
752 /* INSN must either branch to the insn after TEMP2 or the insn
753 after TEMP2 must branch to the same place as INSN. */
754 && (reallabelprev
== temp2
755 || ((temp5
= next_active_insn (temp2
)) != 0
756 && simplejump_p (temp5
)
757 && JUMP_LABEL (temp5
) == JUMP_LABEL (insn
))))
759 /* The test expression, X, may be a complicated test with
760 multiple branches. See if we can find all the uses of
761 the label that TEMP branches to without hitting a CALL_INSN
762 or a jump to somewhere else. */
763 rtx target
= JUMP_LABEL (temp
);
764 int nuses
= LABEL_NUSES (target
);
767 /* Set P to the first jump insn that goes around "x = a;". */
768 for (p
= temp
; nuses
&& p
; p
= prev_nonnote_insn (p
))
770 if (GET_CODE (p
) == JUMP_INSN
)
772 if (condjump_p (p
) && ! simplejump_p (p
)
773 && JUMP_LABEL (p
) == target
)
782 else if (GET_CODE (p
) == CALL_INSN
)
787 /* We cannot insert anything between a set of cc and its use
788 so if P uses cc0, we must back up to the previous insn. */
789 q
= prev_nonnote_insn (p
);
790 if (q
&& GET_RTX_CLASS (GET_CODE (q
)) == 'i'
791 && sets_cc0_p (PATTERN (q
)))
798 /* If we found all the uses and there was no data conflict, we
799 can move the assignment unless we can branch into the middle
802 && no_labels_between_p (p
, insn
)
803 && ! reg_referenced_between_p (temp1
, p
, NEXT_INSN (temp3
))
804 && ! reg_set_between_p (temp1
, p
, temp3
)
805 && (GET_CODE (SET_SRC (temp4
)) == CONST_INT
806 || ! reg_set_between_p (SET_SRC (temp4
), p
, temp2
)))
808 emit_insn_after_with_line_notes (PATTERN (temp2
), p
, temp2
);
811 /* Set NEXT to an insn that we know won't go away. */
812 next
= next_active_insn (insn
);
814 /* Delete the jump around the set. Note that we must do
815 this before we redirect the test jumps so that it won't
816 delete the code immediately following the assignment
817 we moved (which might be a jump). */
821 /* We either have two consecutive labels or a jump to
822 a jump, so adjust all the JUMP_INSNs to branch to where
824 for (p
= NEXT_INSN (p
); p
!= next
; p
= NEXT_INSN (p
))
825 if (GET_CODE (p
) == JUMP_INSN
)
826 redirect_jump (p
, target
);
834 /* If we have if (...) x = exp; and branches are expensive,
835 EXP is a single insn, does not have any side effects, cannot
836 trap, and is not too costly, convert this to
837 t = exp; if (...) x = t;
839 Don't do this when we have CC0 because it is unlikely to help
840 and we'd need to worry about where to place the new insn and
841 the potential for conflicts. We also can't do this when we have
842 notes on the insn for the same reason as above.
846 TEMP to the "x = exp;" insn.
847 TEMP1 to the single set in the "x = exp; insn.
850 if (! reload_completed
851 && this_is_condjump
&& ! this_is_simplejump
853 && (temp
= next_nonnote_insn (insn
)) != 0
854 && GET_CODE (temp
) == INSN
855 && REG_NOTES (temp
) == 0
856 && (reallabelprev
== temp
857 || ((temp2
= next_active_insn (temp
)) != 0
858 && simplejump_p (temp2
)
859 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
860 && (temp1
= single_set (temp
)) != 0
861 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
862 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
863 #ifdef SMALL_REGISTER_CLASSES
864 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
866 && GET_CODE (SET_SRC (temp1
)) != REG
867 && GET_CODE (SET_SRC (temp1
)) != SUBREG
868 && GET_CODE (SET_SRC (temp1
)) != CONST_INT
869 && ! side_effects_p (SET_SRC (temp1
))
870 && ! may_trap_p (SET_SRC (temp1
))
871 && rtx_cost (SET_SRC (temp1
)) < 10)
873 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
875 if (validate_change (temp
, &SET_DEST (temp1
), new, 0))
877 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
878 emit_insn_after_with_line_notes (PATTERN (temp
),
879 PREV_INSN (insn
), temp
);
881 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
885 /* Similarly, if it takes two insns to compute EXP but they
886 have the same destination. Here TEMP3 will be the second
887 insn and TEMP4 the SET from that insn. */
889 if (! reload_completed
890 && this_is_condjump
&& ! this_is_simplejump
892 && (temp
= next_nonnote_insn (insn
)) != 0
893 && GET_CODE (temp
) == INSN
894 && REG_NOTES (temp
) == 0
895 && (temp3
= next_nonnote_insn (temp
)) != 0
896 && GET_CODE (temp3
) == INSN
897 && REG_NOTES (temp3
) == 0
898 && (reallabelprev
== temp3
899 || ((temp2
= next_active_insn (temp3
)) != 0
900 && simplejump_p (temp2
)
901 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
902 && (temp1
= single_set (temp
)) != 0
903 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
904 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
905 #ifdef SMALL_REGISTER_CLASSES
906 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
908 && ! side_effects_p (SET_SRC (temp1
))
909 && ! may_trap_p (SET_SRC (temp1
))
910 && rtx_cost (SET_SRC (temp1
)) < 10
911 && (temp4
= single_set (temp3
)) != 0
912 && rtx_equal_p (SET_DEST (temp4
), temp2
)
913 && ! side_effects_p (SET_SRC (temp4
))
914 && ! may_trap_p (SET_SRC (temp4
))
915 && rtx_cost (SET_SRC (temp4
)) < 10)
917 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
919 if (validate_change (temp
, &SET_DEST (temp1
), new, 0))
921 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
922 emit_insn_after_with_line_notes (PATTERN (temp
),
923 PREV_INSN (insn
), temp
);
924 emit_insn_after_with_line_notes
925 (replace_rtx (PATTERN (temp3
), temp2
, new),
926 PREV_INSN (insn
), temp3
);
929 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
933 /* Finally, handle the case where two insns are used to
934 compute EXP but a temporary register is used. Here we must
935 ensure that the temporary register is not used anywhere else. */
937 if (! reload_completed
939 && this_is_condjump
&& ! this_is_simplejump
941 && (temp
= next_nonnote_insn (insn
)) != 0
942 && GET_CODE (temp
) == INSN
943 && REG_NOTES (temp
) == 0
944 && (temp3
= next_nonnote_insn (temp
)) != 0
945 && GET_CODE (temp3
) == INSN
946 && REG_NOTES (temp3
) == 0
947 && (reallabelprev
== temp3
948 || ((temp2
= next_active_insn (temp3
)) != 0
949 && simplejump_p (temp2
)
950 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
951 && (temp1
= single_set (temp
)) != 0
952 && (temp5
= SET_DEST (temp1
),
953 (GET_CODE (temp5
) == REG
954 || (GET_CODE (temp5
) == SUBREG
955 && (temp5
= SUBREG_REG (temp5
),
956 GET_CODE (temp5
) == REG
))))
957 && REGNO (temp5
) >= FIRST_PSEUDO_REGISTER
958 && regno_first_uid
[REGNO (temp5
)] == INSN_UID (temp
)
959 && regno_last_uid
[REGNO (temp5
)] == INSN_UID (temp3
)
960 && ! side_effects_p (SET_SRC (temp1
))
961 && ! may_trap_p (SET_SRC (temp1
))
962 && rtx_cost (SET_SRC (temp1
)) < 10
963 && (temp4
= single_set (temp3
)) != 0
964 && (temp2
= SET_DEST (temp4
), GET_CODE (temp2
) == REG
)
965 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
966 #ifdef SMALL_REGISTER_CLASSES
967 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
969 && rtx_equal_p (SET_DEST (temp4
), temp2
)
970 && ! side_effects_p (SET_SRC (temp4
))
971 && ! may_trap_p (SET_SRC (temp4
))
972 && rtx_cost (SET_SRC (temp4
)) < 10)
974 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
976 if (validate_change (temp3
, &SET_DEST (temp4
), new, 0))
978 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
979 emit_insn_after_with_line_notes (PATTERN (temp
),
980 PREV_INSN (insn
), temp
);
981 emit_insn_after_with_line_notes (PATTERN (temp3
),
982 PREV_INSN (insn
), temp3
);
985 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
988 #endif /* HAVE_cc0 */
990 /* We deal with four cases:
992 1) x = a; if (...) x = b; and either A or B is zero,
993 2) if (...) x = 0; and jumps are expensive,
994 3) x = a; if (...) x = b; and A and B are constants where all the
995 set bits in A are also set in B and jumps are expensive, and
996 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
998 5) if (...) x = b; if jumps are even more expensive.
1000 In each of these try to use a store-flag insn to avoid the jump.
1001 (If the jump would be faster, the machine should not have
1002 defined the scc insns!). These cases are often made by the
1003 previous optimization.
1005 INSN here is the jump around the store. We set:
1007 TEMP to the "x = b;" insn.
1009 TEMP2 to B (const0_rtx in the second case).
1010 TEMP3 to A (X in the second case).
1011 TEMP4 to the condition being tested.
1012 TEMP5 to the earliest insn used to find the condition. */
1014 if (/* We can't do this after reload has completed. */
1016 && this_is_condjump
&& ! this_is_simplejump
1017 /* Set TEMP to the "x = b;" insn. */
1018 && (temp
= next_nonnote_insn (insn
)) != 0
1019 && GET_CODE (temp
) == INSN
1020 && GET_CODE (PATTERN (temp
)) == SET
1021 && GET_CODE (temp1
= SET_DEST (PATTERN (temp
))) == REG
1022 #ifdef SMALL_REGISTER_CLASSES
1023 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
1025 && GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
1026 && (GET_CODE (temp2
= SET_SRC (PATTERN (temp
))) == REG
1027 || GET_CODE (temp2
) == SUBREG
1028 || GET_CODE (temp2
) == CONST_INT
)
1029 /* Allow either form, but prefer the former if both apply.
1030 There is no point in using the old value of TEMP1 if
1031 it is a register, since cse will alias them. It can
1032 lose if the old value were a hard register since CSE
1033 won't replace hard registers. */
1034 && (((temp3
= reg_set_last (temp1
, insn
)) != 0
1035 && GET_CODE (temp3
) == CONST_INT
)
1036 /* Make the latter case look like x = x; if (...) x = 0; */
1039 && temp2
== const0_rtx
)
1040 #ifdef HAVE_conditional_move
1041 || HAVE_conditional_move
1043 || BRANCH_COST
>= 3)))
1044 /* INSN must either branch to the insn after TEMP or the insn
1045 after TEMP must branch to the same place as INSN. */
1046 && (reallabelprev
== temp
1047 || ((temp4
= next_active_insn (temp
)) != 0
1048 && simplejump_p (temp4
)
1049 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
1050 && (temp4
= get_condition (insn
, &temp5
)) != 0
1051 /* We must be comparing objects whose modes imply the size.
1052 We could handle BLKmode if (1) emit_store_flag could
1053 and (2) we could find the size reliably. */
1054 && GET_MODE (XEXP (temp4
, 0)) != BLKmode
1056 /* If B is zero, OK; if A is zero, can only do (1) if we
1057 can reverse the condition. See if (3) applies possibly
1058 by reversing the condition. Prefer reversing to (4) when
1059 branches are very expensive. */
1060 && ((reversep
= 0, temp2
== const0_rtx
)
1061 || (temp3
== const0_rtx
1062 && (reversep
= can_reverse_comparison_p (temp4
, insn
)))
1063 || (BRANCH_COST
>= 2
1064 && GET_CODE (temp2
) == CONST_INT
1065 && GET_CODE (temp3
) == CONST_INT
1066 && ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp2
)
1067 || ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp3
)
1068 && (reversep
= can_reverse_comparison_p (temp4
,
1070 #ifdef HAVE_conditional_move
1071 || HAVE_conditional_move
1073 || BRANCH_COST
>= 3)
1075 /* If the previous insn sets CC0 and something else, we can't
1076 do this since we are going to delete that insn. */
1078 && ! ((temp6
= prev_nonnote_insn (insn
)) != 0
1079 && GET_CODE (temp6
) == INSN
1080 && (sets_cc0_p (PATTERN (temp6
)) == -1
1081 || (sets_cc0_p (PATTERN (temp6
)) == 1
1082 && FIND_REG_INC_NOTE (temp6
, NULL_RTX
))))
1086 enum rtx_code code
= GET_CODE (temp4
);
1087 rtx uval
, cval
, var
= temp1
;
1091 /* If necessary, reverse the condition. */
1093 code
= reverse_condition (code
), uval
= temp2
, cval
= temp3
;
1095 uval
= temp3
, cval
= temp2
;
1097 /* See if we can do this with a store-flag insn. */
1100 /* If CVAL is non-zero, normalize to -1. Otherwise,
1101 if UVAL is the constant 1, it is best to just compute
1102 the result directly. If UVAL is constant and STORE_FLAG_VALUE
1103 includes all of its bits, it is best to compute the flag
1104 value unnormalized and `and' it with UVAL. Otherwise,
1105 normalize to -1 and `and' with UVAL. */
1106 normalizep
= (cval
!= const0_rtx
? -1
1107 : (uval
== const1_rtx
? 1
1108 : (GET_CODE (uval
) == CONST_INT
1109 && (INTVAL (uval
) & ~STORE_FLAG_VALUE
) == 0)
1112 /* We will be putting the store-flag insn immediately in
1113 front of the comparison that was originally being done,
1114 so we know all the variables in TEMP4 will be valid.
1115 However, this might be in front of the assignment of
1116 A to VAR. If it is, it would clobber the store-flag
1117 we will be emitting.
1119 Therefore, emit into a temporary which will be copied to
1120 VAR immediately after TEMP. */
1122 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
1123 XEXP (temp4
, 0), XEXP (temp4
, 1),
1125 (code
== LTU
|| code
== LEU
1126 || code
== GEU
|| code
== GTU
),
1133 /* Put the store-flag insns in front of the first insn
1134 used to compute the condition to ensure that we
1135 use the same values of them as the current
1136 comparison. However, the remainder of the insns we
1137 generate will be placed directly in front of the
1138 jump insn, in case any of the pseudos we use
1139 are modified earlier. */
1144 emit_insns_before (seq
, temp5
);
1148 /* Both CVAL and UVAL are non-zero. */
1149 if (cval
!= const0_rtx
&& uval
!= const0_rtx
)
1153 tem1
= expand_and (uval
, target
, NULL_RTX
);
1154 if (GET_CODE (cval
) == CONST_INT
1155 && GET_CODE (uval
) == CONST_INT
1156 && (INTVAL (cval
) & INTVAL (uval
)) == INTVAL (cval
))
1160 tem2
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1161 target
, NULL_RTX
, 0);
1162 tem2
= expand_and (cval
, tem2
,
1163 (GET_CODE (tem2
) == REG
1167 /* If we usually make new pseudos, do so here. This
1168 turns out to help machines that have conditional
1171 if (flag_expensive_optimizations
)
1174 target
= expand_binop (GET_MODE (var
), ior_optab
,
1178 else if (normalizep
!= 1)
1180 /* We know that either CVAL or UVAL is zero. If
1181 UVAL is zero, negate TARGET and `and' with CVAL.
1182 Otherwise, `and' with UVAL. */
1183 if (uval
== const0_rtx
)
1185 target
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1186 target
, NULL_RTX
, 0);
1190 target
= expand_and (uval
, target
,
1191 (GET_CODE (target
) == REG
1192 && ! preserve_subexpressions_p ()
1193 ? target
: NULL_RTX
));
1196 emit_move_insn (var
, target
);
1201 /* If INSN uses CC0, we must not separate it from the
1202 insn that sets cc0. */
1204 if (reg_mentioned_p (cc0_rtx
, PATTERN (before
)))
1205 before
= prev_nonnote_insn (before
);
1208 emit_insns_before (seq
, before
);
1211 next
= NEXT_INSN (insn
);
1221 /* If branches are expensive, convert
1222 if (foo) bar++; to bar += (foo != 0);
1223 and similarly for "bar--;"
1225 INSN is the conditional branch around the arithmetic. We set:
1227 TEMP is the arithmetic insn.
1228 TEMP1 is the SET doing the arithmetic.
1229 TEMP2 is the operand being incremented or decremented.
1230 TEMP3 to the condition being tested.
1231 TEMP4 to the earliest insn used to find the condition. */
1233 if ((BRANCH_COST
>= 2
1241 && ! reload_completed
1242 && this_is_condjump
&& ! this_is_simplejump
1243 && (temp
= next_nonnote_insn (insn
)) != 0
1244 && (temp1
= single_set (temp
)) != 0
1245 && (temp2
= SET_DEST (temp1
),
1246 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
1247 && GET_CODE (SET_SRC (temp1
)) == PLUS
1248 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1249 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
1250 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
1251 /* INSN must either branch to the insn after TEMP or the insn
1252 after TEMP must branch to the same place as INSN. */
1253 && (reallabelprev
== temp
1254 || ((temp3
= next_active_insn (temp
)) != 0
1255 && simplejump_p (temp3
)
1256 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
1257 && (temp3
= get_condition (insn
, &temp4
)) != 0
1258 /* We must be comparing objects whose modes imply the size.
1259 We could handle BLKmode if (1) emit_store_flag could
1260 and (2) we could find the size reliably. */
1261 && GET_MODE (XEXP (temp3
, 0)) != BLKmode
1262 && can_reverse_comparison_p (temp3
, insn
))
1264 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
1265 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
1269 /* It must be the case that TEMP2 is not modified in the range
1270 [TEMP4, INSN). The one exception we make is if the insn
1271 before INSN sets TEMP2 to something which is also unchanged
1272 in that range. In that case, we can move the initialization
1273 into our sequence. */
1275 if ((temp5
= prev_active_insn (insn
)) != 0
1276 && GET_CODE (temp5
) == INSN
1277 && (temp6
= single_set (temp5
)) != 0
1278 && rtx_equal_p (temp2
, SET_DEST (temp6
))
1279 && (CONSTANT_P (SET_SRC (temp6
))
1280 || GET_CODE (SET_SRC (temp6
)) == REG
1281 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
1283 emit_insn (PATTERN (temp5
));
1285 init
= SET_SRC (temp6
);
1288 if (CONSTANT_P (init
)
1289 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
1290 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
1291 XEXP (temp3
, 0), XEXP (temp3
, 1),
1293 (code
== LTU
|| code
== LEU
1294 || code
== GTU
|| code
== GEU
), 1);
1296 /* If we can do the store-flag, do the addition or
1300 target
= expand_binop (GET_MODE (temp2
),
1301 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1302 ? add_optab
: sub_optab
),
1303 temp2
, target
, temp2
, 0, OPTAB_WIDEN
);
1307 /* Put the result back in temp2 in case it isn't already.
1308 Then replace the jump, possible a CC0-setting insn in
1309 front of the jump, and TEMP, with the sequence we have
1312 if (target
!= temp2
)
1313 emit_move_insn (temp2
, target
);
1318 emit_insns_before (seq
, temp4
);
1322 delete_insn (init_insn
);
1324 next
= NEXT_INSN (insn
);
1326 delete_insn (prev_nonnote_insn (insn
));
1336 /* Simplify if (...) x = 1; else {...} if (x) ...
1337 We recognize this case scanning backwards as well.
1339 TEMP is the assignment to x;
1340 TEMP1 is the label at the head of the second if. */
1341 /* ?? This should call get_condition to find the values being
1342 compared, instead of looking for a COMPARE insn when HAVE_cc0
1343 is not defined. This would allow it to work on the m88k. */
1344 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1345 is not defined and the condition is tested by a separate compare
1346 insn. This is because the code below assumes that the result
1347 of the compare dies in the following branch.
1349 Not only that, but there might be other insns between the
1350 compare and branch whose results are live. Those insns need
1353 A way to fix this is to move the insns at JUMP_LABEL (insn)
1354 to before INSN. If we are running before flow, they will
1355 be deleted if they aren't needed. But this doesn't work
1358 This is really a special-case of jump threading, anyway. The
1359 right thing to do is to replace this and jump threading with
1360 much simpler code in cse.
1362 This code has been turned off in the non-cc0 case in the
1366 else if (this_is_simplejump
1367 /* Safe to skip USE and CLOBBER insns here
1368 since they will not be deleted. */
1369 && (temp
= prev_active_insn (insn
))
1370 && no_labels_between_p (temp
, insn
)
1371 && GET_CODE (temp
) == INSN
1372 && GET_CODE (PATTERN (temp
)) == SET
1373 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1374 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1375 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1376 /* If we find that the next value tested is `x'
1377 (TEMP1 is the insn where this happens), win. */
1378 && GET_CODE (temp1
) == INSN
1379 && GET_CODE (PATTERN (temp1
)) == SET
1381 /* Does temp1 `tst' the value of x? */
1382 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1383 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1384 && (temp1
= next_nonnote_insn (temp1
))
1386 /* Does temp1 compare the value of x against zero? */
1387 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1388 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1389 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1390 == SET_DEST (PATTERN (temp
)))
1391 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1392 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1394 && condjump_p (temp1
))
1396 /* Get the if_then_else from the condjump. */
1397 rtx choice
= SET_SRC (PATTERN (temp1
));
1398 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1400 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1401 rtx val
= SET_SRC (PATTERN (temp
));
1403 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1407 if (cond
== const_true_rtx
)
1408 ultimate
= XEXP (choice
, 1);
1409 else if (cond
== const0_rtx
)
1410 ultimate
= XEXP (choice
, 2);
1414 if (ultimate
== pc_rtx
)
1415 ultimate
= get_label_after (temp1
);
1416 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1417 ultimate
= XEXP (ultimate
, 0);
1420 changed
|= redirect_jump (insn
, ultimate
);
1426 /* @@ This needs a bit of work before it will be right.
1428 Any type of comparison can be accepted for the first and
1429 second compare. When rewriting the first jump, we must
1430 compute the what conditions can reach label3, and use the
1431 appropriate code. We can not simply reverse/swap the code
1432 of the first jump. In some cases, the second jump must be
1436 < == converts to > ==
1437 < != converts to == >
1440 If the code is written to only accept an '==' test for the second
1441 compare, then all that needs to be done is to swap the condition
1442 of the first branch.
1444 It is questionable whether we want this optimization anyways,
1445 since if the user wrote code like this because he/she knew that
1446 the jump to label1 is taken most of the time, then rewriting
1447 this gives slower code. */
1448 /* @@ This should call get_condition to find the values being
1449 compared, instead of looking for a COMPARE insn when HAVE_cc0
1450 is not defined. This would allow it to work on the m88k. */
1451 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1452 is not defined and the condition is tested by a separate compare
1453 insn. This is because the code below assumes that the result
1454 of the compare dies in the following branch. */
1456 /* Simplify test a ~= b
1470 where ~= is an inequality, e.g. >, and ~~= is the swapped
1473 We recognize this case scanning backwards.
1475 TEMP is the conditional jump to `label2';
1476 TEMP1 is the test for `a == b';
1477 TEMP2 is the conditional jump to `label1';
1478 TEMP3 is the test for `a ~= b'. */
1479 else if (this_is_simplejump
1480 && (temp
= prev_active_insn (insn
))
1481 && no_labels_between_p (temp
, insn
)
1482 && condjump_p (temp
)
1483 && (temp1
= prev_active_insn (temp
))
1484 && no_labels_between_p (temp1
, temp
)
1485 && GET_CODE (temp1
) == INSN
1486 && GET_CODE (PATTERN (temp1
)) == SET
1488 && sets_cc0_p (PATTERN (temp1
)) == 1
1490 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1491 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1492 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1494 && (temp2
= prev_active_insn (temp1
))
1495 && no_labels_between_p (temp2
, temp1
)
1496 && condjump_p (temp2
)
1497 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1498 && (temp3
= prev_active_insn (temp2
))
1499 && no_labels_between_p (temp3
, temp2
)
1500 && GET_CODE (PATTERN (temp3
)) == SET
1501 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1502 SET_DEST (PATTERN (temp1
)))
1503 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1504 SET_SRC (PATTERN (temp3
)))
1505 && ! inequality_comparisons_p (PATTERN (temp
))
1506 && inequality_comparisons_p (PATTERN (temp2
)))
1508 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1510 ++LABEL_NUSES (fallthrough_label
);
1511 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1517 if (--LABEL_NUSES (fallthrough_label
) == 0)
1518 delete_insn (fallthrough_label
);
1521 /* Simplify if (...) {... x = 1;} if (x) ...
1523 We recognize this case backwards.
1525 TEMP is the test of `x';
1526 TEMP1 is the assignment to `x' at the end of the
1527 previous statement. */
1528 /* @@ This should call get_condition to find the values being
1529 compared, instead of looking for a COMPARE insn when HAVE_cc0
1530 is not defined. This would allow it to work on the m88k. */
1531 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1532 is not defined and the condition is tested by a separate compare
1533 insn. This is because the code below assumes that the result
1534 of the compare dies in the following branch. */
1536 /* ??? This has to be turned off. The problem is that the
1537 unconditional jump might indirectly end up branching to the
1538 label between TEMP1 and TEMP. We can't detect this, in general,
1539 since it may become a jump to there after further optimizations.
1540 If that jump is done, it will be deleted, so we will retry
1541 this optimization in the next pass, thus an infinite loop.
1543 The present code prevents this by putting the jump after the
1544 label, but this is not logically correct. */
1546 else if (this_is_condjump
1547 /* Safe to skip USE and CLOBBER insns here
1548 since they will not be deleted. */
1549 && (temp
= prev_active_insn (insn
))
1550 && no_labels_between_p (temp
, insn
)
1551 && GET_CODE (temp
) == INSN
1552 && GET_CODE (PATTERN (temp
)) == SET
1554 && sets_cc0_p (PATTERN (temp
)) == 1
1555 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1557 /* Temp must be a compare insn, we can not accept a register
1558 to register move here, since it may not be simply a
1560 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1561 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1562 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1563 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1564 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1566 /* May skip USE or CLOBBER insns here
1567 for checking for opportunity, since we
1568 take care of them later. */
1569 && (temp1
= prev_active_insn (temp
))
1570 && GET_CODE (temp1
) == INSN
1571 && GET_CODE (PATTERN (temp1
)) == SET
1573 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1575 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1576 == SET_DEST (PATTERN (temp1
)))
1578 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1579 /* If this isn't true, cse will do the job. */
1580 && ! no_labels_between_p (temp1
, temp
))
1582 /* Get the if_then_else from the condjump. */
1583 rtx choice
= SET_SRC (PATTERN (insn
));
1584 if (GET_CODE (choice
) == IF_THEN_ELSE
1585 && (GET_CODE (XEXP (choice
, 0)) == EQ
1586 || GET_CODE (XEXP (choice
, 0)) == NE
))
1588 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1593 /* Get the place that condjump will jump to
1594 if it is reached from here. */
1595 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1597 ultimate
= XEXP (choice
, 1);
1599 ultimate
= XEXP (choice
, 2);
1600 /* Get it as a CODE_LABEL. */
1601 if (ultimate
== pc_rtx
)
1602 ultimate
= get_label_after (insn
);
1604 /* Get the label out of the LABEL_REF. */
1605 ultimate
= XEXP (ultimate
, 0);
1607 /* Insert the jump immediately before TEMP, specifically
1608 after the label that is between TEMP1 and TEMP. */
1609 last_insn
= PREV_INSN (temp
);
1611 /* If we would be branching to the next insn, the jump
1612 would immediately be deleted and the re-inserted in
1613 a subsequent pass over the code. So don't do anything
1615 if (next_active_insn (last_insn
)
1616 != next_active_insn (ultimate
))
1618 emit_barrier_after (last_insn
);
1619 p
= emit_jump_insn_after (gen_jump (ultimate
),
1621 JUMP_LABEL (p
) = ultimate
;
1622 ++LABEL_NUSES (ultimate
);
1623 if (INSN_UID (ultimate
) < max_jump_chain
1624 && INSN_CODE (p
) < max_jump_chain
)
1626 jump_chain
[INSN_UID (p
)]
1627 = jump_chain
[INSN_UID (ultimate
)];
1628 jump_chain
[INSN_UID (ultimate
)] = p
;
1636 /* Detect a conditional jump going to the same place
1637 as an immediately following unconditional jump. */
1638 else if (this_is_condjump
1639 && (temp
= next_active_insn (insn
)) != 0
1640 && simplejump_p (temp
)
1641 && (next_active_insn (JUMP_LABEL (insn
))
1642 == next_active_insn (JUMP_LABEL (temp
))))
1648 /* Detect a conditional jump jumping over an unconditional jump. */
1650 else if ((this_is_condjump
|| this_is_condjump_in_parallel
)
1651 && ! this_is_simplejump
1652 && reallabelprev
!= 0
1653 && GET_CODE (reallabelprev
) == JUMP_INSN
1654 && prev_active_insn (reallabelprev
) == insn
1655 && no_labels_between_p (insn
, reallabelprev
)
1656 && simplejump_p (reallabelprev
))
1658 /* When we invert the unconditional jump, we will be
1659 decrementing the usage count of its old label.
1660 Make sure that we don't delete it now because that
1661 might cause the following code to be deleted. */
1662 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
1663 rtx prev_label
= JUMP_LABEL (insn
);
1666 ++LABEL_NUSES (prev_label
);
1668 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
1670 /* It is very likely that if there are USE insns before
1671 this jump, they hold REG_DEAD notes. These REG_DEAD
1672 notes are no longer valid due to this optimization,
1673 and will cause the life-analysis that following passes
1674 (notably delayed-branch scheduling) to think that
1675 these registers are dead when they are not.
1677 To prevent this trouble, we just remove the USE insns
1678 from the insn chain. */
1680 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
1681 && GET_CODE (PATTERN (prev_uses
)) == USE
)
1683 rtx useless
= prev_uses
;
1684 prev_uses
= prev_nonnote_insn (prev_uses
);
1685 delete_insn (useless
);
1688 delete_insn (reallabelprev
);
1693 /* We can now safely delete the label if it is unreferenced
1694 since the delete_insn above has deleted the BARRIER. */
1695 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
1696 delete_insn (prev_label
);
1701 /* Detect a jump to a jump. */
1703 nlabel
= follow_jumps (JUMP_LABEL (insn
));
1704 if (nlabel
!= JUMP_LABEL (insn
)
1705 && redirect_jump (insn
, nlabel
))
1711 /* Look for if (foo) bar; else break; */
1712 /* The insns look like this:
1713 insn = condjump label1;
1714 ...range1 (some insns)...
1717 ...range2 (some insns)...
1718 jump somewhere unconditionally
1721 rtx label1
= next_label (insn
);
1722 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1723 /* Don't do this optimization on the first round, so that
1724 jump-around-a-jump gets simplified before we ask here
1725 whether a jump is unconditional.
1727 Also don't do it when we are called after reload since
1728 it will confuse reorg. */
1730 && (reload_completed
? ! flag_delayed_branch
: 1)
1731 /* Make sure INSN is something we can invert. */
1732 && condjump_p (insn
)
1734 && JUMP_LABEL (insn
) == label1
1735 && LABEL_NUSES (label1
) == 1
1736 && GET_CODE (range1end
) == JUMP_INSN
1737 && simplejump_p (range1end
))
1739 rtx label2
= next_label (label1
);
1740 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
1741 if (range1end
!= range2end
1742 && JUMP_LABEL (range1end
) == label2
1743 && GET_CODE (range2end
) == JUMP_INSN
1744 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
1745 /* Invert the jump condition, so we
1746 still execute the same insns in each case. */
1747 && invert_jump (insn
, label1
))
1749 rtx range1beg
= next_active_insn (insn
);
1750 rtx range2beg
= next_active_insn (label1
);
1751 rtx range1after
, range2after
;
1752 rtx range1before
, range2before
;
1755 /* Include in each range any notes before it, to be
1756 sure that we get the line number note if any, even
1757 if there are other notes here. */
1758 while (PREV_INSN (range1beg
)
1759 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
)
1760 range1beg
= PREV_INSN (range1beg
);
1762 while (PREV_INSN (range2beg
)
1763 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
)
1764 range2beg
= PREV_INSN (range2beg
);
1766 /* Don't move NOTEs for blocks or loops; shift them
1767 outside the ranges, where they'll stay put. */
1768 range1beg
= squeeze_notes (range1beg
, range1end
);
1769 range2beg
= squeeze_notes (range2beg
, range2end
);
1771 /* Get current surrounds of the 2 ranges. */
1772 range1before
= PREV_INSN (range1beg
);
1773 range2before
= PREV_INSN (range2beg
);
1774 range1after
= NEXT_INSN (range1end
);
1775 range2after
= NEXT_INSN (range2end
);
1777 /* Splice range2 where range1 was. */
1778 NEXT_INSN (range1before
) = range2beg
;
1779 PREV_INSN (range2beg
) = range1before
;
1780 NEXT_INSN (range2end
) = range1after
;
1781 PREV_INSN (range1after
) = range2end
;
1782 /* Splice range1 where range2 was. */
1783 NEXT_INSN (range2before
) = range1beg
;
1784 PREV_INSN (range1beg
) = range2before
;
1785 NEXT_INSN (range1end
) = range2after
;
1786 PREV_INSN (range2after
) = range1end
;
1788 /* Check for a loop end note between the end of
1789 range2, and the next code label. If there is one,
1790 then what we have really seen is
1791 if (foo) break; end_of_loop;
1792 and moved the break sequence outside the loop.
1793 We must move the LOOP_END note to where the
1794 loop really ends now, or we will confuse loop
1796 for (;range2after
!= label2
; range2after
= rangenext
)
1798 rangenext
= NEXT_INSN (range2after
);
1799 if (GET_CODE (range2after
) == NOTE
1800 && (NOTE_LINE_NUMBER (range2after
)
1801 == NOTE_INSN_LOOP_END
))
1803 NEXT_INSN (PREV_INSN (range2after
))
1805 PREV_INSN (rangenext
)
1806 = PREV_INSN (range2after
);
1807 PREV_INSN (range2after
)
1808 = PREV_INSN (range1beg
);
1809 NEXT_INSN (range2after
) = range1beg
;
1810 NEXT_INSN (PREV_INSN (range1beg
))
1812 PREV_INSN (range1beg
) = range2after
;
1821 /* Now that the jump has been tensioned,
1822 try cross jumping: check for identical code
1823 before the jump and before its target label. */
1825 /* First, cross jumping of conditional jumps: */
1827 if (cross_jump
&& condjump_p (insn
))
1829 rtx newjpos
, newlpos
;
1830 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
1832 /* A conditional jump may be crossjumped
1833 only if the place it jumps to follows
1834 an opposing jump that comes back here. */
1836 if (x
!= 0 && ! jump_back_p (x
, insn
))
1837 /* We have no opposing jump;
1838 cannot cross jump this insn. */
1842 /* TARGET is nonzero if it is ok to cross jump
1843 to code before TARGET. If so, see if matches. */
1845 find_cross_jump (insn
, x
, 2,
1846 &newjpos
, &newlpos
);
1850 do_cross_jump (insn
, newjpos
, newlpos
);
1851 /* Make the old conditional jump
1852 into an unconditional one. */
1853 SET_SRC (PATTERN (insn
))
1854 = gen_rtx (LABEL_REF
, VOIDmode
, JUMP_LABEL (insn
));
1855 INSN_CODE (insn
) = -1;
1856 emit_barrier_after (insn
);
1857 /* Add to jump_chain unless this is a new label
1858 whose UID is too large. */
1859 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
1861 jump_chain
[INSN_UID (insn
)]
1862 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1863 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
1870 /* Cross jumping of unconditional jumps:
1871 a few differences. */
1873 if (cross_jump
&& simplejump_p (insn
))
1875 rtx newjpos
, newlpos
;
1880 /* TARGET is nonzero if it is ok to cross jump
1881 to code before TARGET. If so, see if matches. */
1882 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
1883 &newjpos
, &newlpos
);
1885 /* If cannot cross jump to code before the label,
1886 see if we can cross jump to another jump to
1888 /* Try each other jump to this label. */
1889 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
1890 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1891 target
!= 0 && newjpos
== 0;
1892 target
= jump_chain
[INSN_UID (target
)])
1894 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
1895 /* Ignore TARGET if it's deleted. */
1896 && ! INSN_DELETED_P (target
))
1897 find_cross_jump (insn
, target
, 2,
1898 &newjpos
, &newlpos
);
1902 do_cross_jump (insn
, newjpos
, newlpos
);
1908 /* This code was dead in the previous jump.c! */
1909 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
1911 /* Return insns all "jump to the same place"
1912 so we can cross-jump between any two of them. */
1914 rtx newjpos
, newlpos
, target
;
1918 /* If cannot cross jump to code before the label,
1919 see if we can cross jump to another jump to
1921 /* Try each other jump to this label. */
1922 for (target
= jump_chain
[0];
1923 target
!= 0 && newjpos
== 0;
1924 target
= jump_chain
[INSN_UID (target
)])
1926 && ! INSN_DELETED_P (target
)
1927 && GET_CODE (PATTERN (target
)) == RETURN
)
1928 find_cross_jump (insn
, target
, 2,
1929 &newjpos
, &newlpos
);
1933 do_cross_jump (insn
, newjpos
, newlpos
);
1944 /* Delete extraneous line number notes.
1945 Note that two consecutive notes for different lines are not really
1946 extraneous. There should be some indication where that line belonged,
1947 even if it became empty. */
1952 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
1953 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
1955 /* Delete this note if it is identical to previous note. */
1957 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
1958 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
1971 /* If we fall through to the epilogue, see if we can insert a RETURN insn
1972 in front of it. If the machine allows it at this point (we might be
1973 after reload for a leaf routine), it will improve optimization for it
1974 to be there. We do this both here and at the start of this pass since
1975 the RETURN might have been deleted by some of our optimizations. */
1976 insn
= get_last_insn ();
1977 while (insn
&& GET_CODE (insn
) == NOTE
)
1978 insn
= PREV_INSN (insn
);
1980 if (insn
&& GET_CODE (insn
) != BARRIER
)
1982 emit_jump_insn (gen_return ());
1988 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1989 If so, delete it, and record that this function can drop off the end. */
1995 /* One label can follow the end-note: the return label. */
1996 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
1997 /* Ordinary insns can follow it if returning a structure. */
1998 || GET_CODE (insn
) == INSN
1999 /* If machine uses explicit RETURN insns, no epilogue,
2000 then one of them follows the note. */
2001 || (GET_CODE (insn
) == JUMP_INSN
2002 && GET_CODE (PATTERN (insn
)) == RETURN
)
2003 /* Other kinds of notes can follow also. */
2004 || (GET_CODE (insn
) == NOTE
2005 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
2006 insn
= PREV_INSN (insn
);
2009 /* Report if control can fall through at the end of the function. */
2010 if (insn
&& GET_CODE (insn
) == NOTE
2011 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
)
2017 /* Show JUMP_CHAIN no longer valid. */
2021 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2022 jump. Assume that this unconditional jump is to the exit test code. If
2023 the code is sufficiently simple, make a copy of it before INSN,
2024 followed by a jump to the exit of the loop. Then delete the unconditional
2027 Note that it is possible we can get confused here if the jump immediately
2028 after the loop start branches outside the loop but within an outer loop.
2029 If we are near the exit of that loop, we will copy its exit test. This
2030 will not generate incorrect code, but could suppress some optimizations.
2031 However, such cases are degenerate loops anyway.
2033 Return 1 if we made the change, else 0.
2035 This is only safe immediately after a regscan pass because it uses the
2036 values of regno_first_uid and regno_last_uid. */
2039 duplicate_loop_exit_test (loop_start
)
2042 rtx insn
, set
, p
, link
;
2045 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
2047 int max_reg
= max_reg_num ();
2050 /* Scan the exit code. We do not perform this optimization if any insn:
2054 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2055 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2056 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2059 Also, don't do this if the exit code is more than 20 insns. */
2061 for (insn
= exitcode
;
2063 && ! (GET_CODE (insn
) == NOTE
2064 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
2065 insn
= NEXT_INSN (insn
))
2067 switch (GET_CODE (insn
))
2073 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2074 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2075 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
2080 if (++num_insns
> 20
2081 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
2082 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2088 /* Unless INSN is zero, we can do the optimization. */
2094 /* See if any insn sets a register only used in the loop exit code and
2095 not a user variable. If so, replace it with a new register. */
2096 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2097 if (GET_CODE (insn
) == INSN
2098 && (set
= single_set (insn
)) != 0
2099 && GET_CODE (SET_DEST (set
)) == REG
2100 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
2101 && regno_first_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
))
2103 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
2104 if (regno_last_uid
[REGNO (SET_DEST (set
))] == INSN_UID (p
))
2109 /* We can do the replacement. Allocate reg_map if this is the
2110 first replacement we found. */
2113 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
2114 bzero ((char *) reg_map
, max_reg
* sizeof (rtx
));
2117 REG_LOOP_TEST_P (SET_DEST (set
)) = 1;
2119 reg_map
[REGNO (SET_DEST (set
))]
2120 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
2124 /* Now copy each insn. */
2125 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2126 switch (GET_CODE (insn
))
2129 copy
= emit_barrier_before (loop_start
);
2132 /* Only copy line-number notes. */
2133 if (NOTE_LINE_NUMBER (insn
) >= 0)
2135 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
2136 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
2141 copy
= emit_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2143 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2145 mark_jump_label (PATTERN (copy
), copy
, 0);
2147 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2149 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2150 if (REG_NOTE_KIND (link
) != REG_LABEL
)
2152 = copy_rtx (gen_rtx (EXPR_LIST
, REG_NOTE_KIND (link
),
2153 XEXP (link
, 0), REG_NOTES (copy
)));
2154 if (reg_map
&& REG_NOTES (copy
))
2155 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2159 copy
= emit_jump_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2161 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2162 mark_jump_label (PATTERN (copy
), copy
, 0);
2163 if (REG_NOTES (insn
))
2165 REG_NOTES (copy
) = copy_rtx (REG_NOTES (insn
));
2167 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2170 /* If this is a simple jump, add it to the jump chain. */
2172 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
2173 && simplejump_p (copy
))
2175 jump_chain
[INSN_UID (copy
)]
2176 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2177 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2185 /* Now clean up by emitting a jump to the end label and deleting the jump
2186 at the start of the loop. */
2187 if (! copy
|| GET_CODE (copy
) != BARRIER
)
2189 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
2191 mark_jump_label (PATTERN (copy
), copy
, 0);
2192 if (INSN_UID (copy
) < max_jump_chain
2193 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
2195 jump_chain
[INSN_UID (copy
)]
2196 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2197 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2199 emit_barrier_before (loop_start
);
2202 delete_insn (next_nonnote_insn (loop_start
));
2204 /* Mark the exit code as the virtual top of the converted loop. */
2205 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
2210 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2211 loop-end notes between START and END out before START. Assume that
2212 END is not such a note. START may be such a note. Returns the value
2213 of the new starting insn, which may be different if the original start
2217 squeeze_notes (start
, end
)
2223 for (insn
= start
; insn
!= end
; insn
= next
)
2225 next
= NEXT_INSN (insn
);
2226 if (GET_CODE (insn
) == NOTE
2227 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2228 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2229 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2230 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
2231 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
2232 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
2238 rtx prev
= PREV_INSN (insn
);
2239 PREV_INSN (insn
) = PREV_INSN (start
);
2240 NEXT_INSN (insn
) = start
;
2241 NEXT_INSN (PREV_INSN (insn
)) = insn
;
2242 PREV_INSN (NEXT_INSN (insn
)) = insn
;
2243 NEXT_INSN (prev
) = next
;
2244 PREV_INSN (next
) = prev
;
2252 /* Compare the instructions before insn E1 with those before E2
2253 to find an opportunity for cross jumping.
2254 (This means detecting identical sequences of insns followed by
2255 jumps to the same place, or followed by a label and a jump
2256 to that label, and replacing one with a jump to the other.)
2258 Assume E1 is a jump that jumps to label E2
2259 (that is not always true but it might as well be).
2260 Find the longest possible equivalent sequences
2261 and store the first insns of those sequences into *F1 and *F2.
2262 Store zero there if no equivalent preceding instructions are found.
2264 We give up if we find a label in stream 1.
2265 Actually we could transfer that label into stream 2. */
2268 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
2273 register rtx i1
= e1
, i2
= e2
;
2274 register rtx p1
, p2
;
2277 rtx last1
= 0, last2
= 0;
2278 rtx afterlast1
= 0, afterlast2
= 0;
2286 i1
= prev_nonnote_insn (i1
);
2288 i2
= PREV_INSN (i2
);
2289 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
2290 i2
= PREV_INSN (i2
);
2295 /* Don't allow the range of insns preceding E1 or E2
2296 to include the other (E2 or E1). */
2297 if (i2
== e1
|| i1
== e2
)
2300 /* If we will get to this code by jumping, those jumps will be
2301 tensioned to go directly to the new label (before I2),
2302 so this cross-jumping won't cost extra. So reduce the minimum. */
2303 if (GET_CODE (i1
) == CODE_LABEL
)
2309 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
2315 /* If this is a CALL_INSN, compare register usage information.
2316 If we don't check this on stack register machines, the two
2317 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2318 numbers of stack registers in the same basic block.
2319 If we don't check this on machines with delay slots, a delay slot may
2320 be filled that clobbers a parameter expected by the subroutine.
2322 ??? We take the simple route for now and assume that if they're
2323 equal, they were constructed identically. */
2325 if (GET_CODE (i1
) == CALL_INSN
2326 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1
),
2327 CALL_INSN_FUNCTION_USAGE (i2
)))
2331 /* If cross_jump_death_matters is not 0, the insn's mode
2332 indicates whether or not the insn contains any stack-like
2335 if (!lose
&& cross_jump_death_matters
&& GET_MODE (i1
) == QImode
)
2337 /* If register stack conversion has already been done, then
2338 death notes must also be compared before it is certain that
2339 the two instruction streams match. */
2342 HARD_REG_SET i1_regset
, i2_regset
;
2344 CLEAR_HARD_REG_SET (i1_regset
);
2345 CLEAR_HARD_REG_SET (i2_regset
);
2347 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
2348 if (REG_NOTE_KIND (note
) == REG_DEAD
2349 && STACK_REG_P (XEXP (note
, 0)))
2350 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
2352 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
2353 if (REG_NOTE_KIND (note
) == REG_DEAD
2354 && STACK_REG_P (XEXP (note
, 0)))
2355 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
2357 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
2366 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
2367 || ! rtx_renumbered_equal_p (p1
, p2
))
2369 /* The following code helps take care of G++ cleanups. */
2373 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
2374 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
2375 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
2376 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
2377 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
2378 /* If the equivalences are not to a constant, they may
2379 reference pseudos that no longer exist, so we can't
2381 && CONSTANT_P (XEXP (equiv1
, 0))
2382 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
2384 rtx s1
= single_set (i1
);
2385 rtx s2
= single_set (i2
);
2386 if (s1
!= 0 && s2
!= 0
2387 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
2389 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
2390 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
2391 if (! rtx_renumbered_equal_p (p1
, p2
))
2393 else if (apply_change_group ())
2398 /* Insns fail to match; cross jumping is limited to the following
2402 /* Don't allow the insn after a compare to be shared by
2403 cross-jumping unless the compare is also shared.
2404 Here, if either of these non-matching insns is a compare,
2405 exclude the following insn from possible cross-jumping. */
2406 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
2407 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
2410 /* If cross-jumping here will feed a jump-around-jump
2411 optimization, this jump won't cost extra, so reduce
2413 if (GET_CODE (i1
) == JUMP_INSN
2415 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
2421 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
2423 /* Ok, this insn is potentially includable in a cross-jump here. */
2424 afterlast1
= last1
, afterlast2
= last2
;
2425 last1
= i1
, last2
= i2
, --minimum
;
2429 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
2430 *f1
= last1
, *f2
= last2
;
2434 do_cross_jump (insn
, newjpos
, newlpos
)
2435 rtx insn
, newjpos
, newlpos
;
2437 /* Find an existing label at this point
2438 or make a new one if there is none. */
2439 register rtx label
= get_label_before (newlpos
);
2441 /* Make the same jump insn jump to the new point. */
2442 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2444 /* Remove from jump chain of returns. */
2445 delete_from_jump_chain (insn
);
2446 /* Change the insn. */
2447 PATTERN (insn
) = gen_jump (label
);
2448 INSN_CODE (insn
) = -1;
2449 JUMP_LABEL (insn
) = label
;
2450 LABEL_NUSES (label
)++;
2451 /* Add to new the jump chain. */
2452 if (INSN_UID (label
) < max_jump_chain
2453 && INSN_UID (insn
) < max_jump_chain
)
2455 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
2456 jump_chain
[INSN_UID (label
)] = insn
;
2460 redirect_jump (insn
, label
);
2462 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2463 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2464 the NEWJPOS stream. */
2466 while (newjpos
!= insn
)
2470 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
2471 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
2472 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
2473 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
2474 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
2475 remove_note (newlpos
, lnote
);
2477 delete_insn (newjpos
);
2478 newjpos
= next_real_insn (newjpos
);
2479 newlpos
= next_real_insn (newlpos
);
2483 /* Return the label before INSN, or put a new label there. */
2486 get_label_before (insn
)
2491 /* Find an existing label at this point
2492 or make a new one if there is none. */
2493 label
= prev_nonnote_insn (insn
);
2495 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2497 rtx prev
= PREV_INSN (insn
);
2499 label
= gen_label_rtx ();
2500 emit_label_after (label
, prev
);
2501 LABEL_NUSES (label
) = 0;
2506 /* Return the label after INSN, or put a new label there. */
2509 get_label_after (insn
)
2514 /* Find an existing label at this point
2515 or make a new one if there is none. */
2516 label
= next_nonnote_insn (insn
);
2518 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2520 label
= gen_label_rtx ();
2521 emit_label_after (label
, insn
);
2522 LABEL_NUSES (label
) = 0;
2527 /* Return 1 if INSN is a jump that jumps to right after TARGET
2528 only on the condition that TARGET itself would drop through.
2529 Assumes that TARGET is a conditional jump. */
2532 jump_back_p (insn
, target
)
2536 enum rtx_code codei
, codet
;
2538 if (simplejump_p (insn
) || ! condjump_p (insn
)
2539 || simplejump_p (target
)
2540 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
2543 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
2544 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
2546 codei
= GET_CODE (cinsn
);
2547 codet
= GET_CODE (ctarget
);
2549 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
2551 if (! can_reverse_comparison_p (cinsn
, insn
))
2553 codei
= reverse_condition (codei
);
2556 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
2558 if (! can_reverse_comparison_p (ctarget
, target
))
2560 codet
= reverse_condition (codet
);
2563 return (codei
== codet
2564 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
2565 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
2568 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2569 return non-zero if it is safe to reverse this comparison. It is if our
2570 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2571 this is known to be an integer comparison. */
2574 can_reverse_comparison_p (comparison
, insn
)
2580 /* If this is not actually a comparison, we can't reverse it. */
2581 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
2584 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
2585 /* If this is an NE comparison, it is safe to reverse it to an EQ
2586 comparison and vice versa, even for floating point. If no operands
2587 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2588 always false and NE is always true, so the reversal is also valid. */
2590 || GET_CODE (comparison
) == NE
2591 || GET_CODE (comparison
) == EQ
)
2594 arg0
= XEXP (comparison
, 0);
2596 /* Make sure ARG0 is one of the actual objects being compared. If we
2597 can't do this, we can't be sure the comparison can be reversed.
2599 Handle cc0 and a MODE_CC register. */
2600 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
2606 rtx prev
= prev_nonnote_insn (insn
);
2607 rtx set
= single_set (prev
);
2609 if (set
== 0 || SET_DEST (set
) != arg0
)
2612 arg0
= SET_SRC (set
);
2614 if (GET_CODE (arg0
) == COMPARE
)
2615 arg0
= XEXP (arg0
, 0);
2618 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2619 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2620 return (GET_CODE (arg0
) == CONST_INT
2621 || (GET_MODE (arg0
) != VOIDmode
2622 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
2623 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
2626 /* Given an rtx-code for a comparison, return the code
2627 for the negated comparison.
2628 WATCH OUT! reverse_condition is not safe to use on a jump
2629 that might be acting on the results of an IEEE floating point comparison,
2630 because of the special treatment of non-signaling nans in comparisons.
2631 Use can_reverse_comparison_p to be sure. */
2634 reverse_condition (code
)
2675 /* Similar, but return the code when two operands of a comparison are swapped.
2676 This IS safe for IEEE floating-point. */
2679 swap_condition (code
)
2718 /* Given a comparison CODE, return the corresponding unsigned comparison.
2719 If CODE is an equality comparison or already an unsigned comparison,
2720 CODE is returned. */
2723 unsigned_condition (code
)
2753 /* Similarly, return the signed version of a comparison. */
2756 signed_condition (code
)
2786 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2787 truth of CODE1 implies the truth of CODE2. */
2790 comparison_dominates_p (code1
, code2
)
2791 enum rtx_code code1
, code2
;
2799 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
2804 if (code2
== LE
|| code2
== NE
)
2809 if (code2
== GE
|| code2
== NE
)
2814 if (code2
== LEU
|| code2
== NE
)
2819 if (code2
== GEU
|| code2
== NE
)
2827 /* Return 1 if INSN is an unconditional jump and nothing else. */
2833 return (GET_CODE (insn
) == JUMP_INSN
2834 && GET_CODE (PATTERN (insn
)) == SET
2835 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
2836 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
2839 /* Return nonzero if INSN is a (possibly) conditional jump
2840 and nothing more. */
2846 register rtx x
= PATTERN (insn
);
2847 if (GET_CODE (x
) != SET
)
2849 if (GET_CODE (SET_DEST (x
)) != PC
)
2851 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2853 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2855 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2856 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2857 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2859 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2860 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2861 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2866 /* Return nonzero if INSN is a (possibly) conditional jump
2867 and nothing more. */
2870 condjump_in_parallel_p (insn
)
2873 register rtx x
= PATTERN (insn
);
2875 if (GET_CODE (x
) != PARALLEL
)
2878 x
= XVECEXP (x
, 0, 0);
2880 if (GET_CODE (x
) != SET
)
2882 if (GET_CODE (SET_DEST (x
)) != PC
)
2884 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2886 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2888 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2889 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2890 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2892 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2893 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2894 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2899 /* Return 1 if X is an RTX that does nothing but set the condition codes
2900 and CLOBBER or USE registers.
2901 Return -1 if X does explicitly set the condition codes,
2902 but also does other things. */
2909 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
2911 if (GET_CODE (x
) == PARALLEL
)
2915 int other_things
= 0;
2916 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2918 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
2919 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
2921 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
2924 return ! sets_cc0
? 0 : other_things
? -1 : 1;
2932 /* Follow any unconditional jump at LABEL;
2933 return the ultimate label reached by any such chain of jumps.
2934 If LABEL is not followed by a jump, return LABEL.
2935 If the chain loops or we can't find end, return LABEL,
2936 since that tells caller to avoid changing the insn.
2938 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2939 a USE or CLOBBER. */
2942 follow_jumps (label
)
2947 register rtx value
= label
;
2952 && (insn
= next_active_insn (value
)) != 0
2953 && GET_CODE (insn
) == JUMP_INSN
2954 && (JUMP_LABEL (insn
) != 0 || GET_CODE (PATTERN (insn
)) == RETURN
)
2955 && (next
= NEXT_INSN (insn
))
2956 && GET_CODE (next
) == BARRIER
);
2959 /* Don't chain through the insn that jumps into a loop
2960 from outside the loop,
2961 since that would create multiple loop entry jumps
2962 and prevent loop optimization. */
2964 if (!reload_completed
)
2965 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
2966 if (GET_CODE (tem
) == NOTE
2967 && NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
)
2970 /* If we have found a cycle, make the insn jump to itself. */
2971 if (JUMP_LABEL (insn
) == label
)
2974 tem
= next_active_insn (JUMP_LABEL (insn
));
2975 if (tem
&& (GET_CODE (PATTERN (tem
)) == ADDR_VEC
2976 || GET_CODE (PATTERN (tem
)) == ADDR_DIFF_VEC
))
2979 value
= JUMP_LABEL (insn
);
2986 /* Assuming that field IDX of X is a vector of label_refs,
2987 replace each of them by the ultimate label reached by it.
2988 Return nonzero if a change is made.
2989 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2992 tension_vector_labels (x
, idx
)
2998 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
3000 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
3001 register rtx nlabel
= follow_jumps (olabel
);
3002 if (nlabel
&& nlabel
!= olabel
)
3004 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
3005 ++LABEL_NUSES (nlabel
);
3006 if (--LABEL_NUSES (olabel
) == 0)
3007 delete_insn (olabel
);
3014 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3015 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3016 in INSN, then store one of them in JUMP_LABEL (INSN).
3017 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3018 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3019 Also, when there are consecutive labels, canonicalize on the last of them.
3021 Note that two labels separated by a loop-beginning note
3022 must be kept distinct if we have not yet done loop-optimization,
3023 because the gap between them is where loop-optimize
3024 will want to move invariant code to. CROSS_JUMP tells us
3025 that loop-optimization is done with.
3027 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3028 two labels distinct if they are separated by only USE or CLOBBER insns. */
3031 mark_jump_label (x
, insn
, cross_jump
)
3036 register RTX_CODE code
= GET_CODE (x
);
3054 /* If this is a constant-pool reference, see if it is a label. */
3055 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3056 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3057 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
3062 rtx label
= XEXP (x
, 0);
3067 if (GET_CODE (label
) != CODE_LABEL
)
3070 /* Ignore references to labels of containing functions. */
3071 if (LABEL_REF_NONLOCAL_P (x
))
3074 /* If there are other labels following this one,
3075 replace it with the last of the consecutive labels. */
3076 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
3078 if (GET_CODE (next
) == CODE_LABEL
)
3080 else if (cross_jump
&& GET_CODE (next
) == INSN
3081 && (GET_CODE (PATTERN (next
)) == USE
3082 || GET_CODE (PATTERN (next
)) == CLOBBER
))
3084 else if (GET_CODE (next
) != NOTE
)
3086 else if (! cross_jump
3087 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
3088 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
))
3092 XEXP (x
, 0) = label
;
3093 ++LABEL_NUSES (label
);
3097 if (GET_CODE (insn
) == JUMP_INSN
)
3098 JUMP_LABEL (insn
) = label
;
3100 /* If we've changed OLABEL and we had a REG_LABEL note
3101 for it, update it as well. */
3102 else if (label
!= olabel
3103 && (note
= find_reg_note (insn
, REG_LABEL
, olabel
)) != 0)
3104 XEXP (note
, 0) = label
;
3106 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3108 else if (! find_reg_note (insn
, REG_LABEL
, label
))
3110 rtx next
= next_real_insn (label
);
3111 /* Don't record labels that refer to dispatch tables.
3112 This is not necessary, since the tablejump
3113 references the same label.
3114 And if we did record them, flow.c would make worse code. */
3116 || ! (GET_CODE (next
) == JUMP_INSN
3117 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
3118 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
)))
3119 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_LABEL
, label
,
3126 /* Do walk the labels in a vector, but not the first operand of an
3127 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3131 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
3133 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
3134 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
, cross_jump
);
3139 fmt
= GET_RTX_FORMAT (code
);
3140 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3143 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
3144 else if (fmt
[i
] == 'E')
3147 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3148 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
3153 /* If all INSN does is set the pc, delete it,
3154 and delete the insn that set the condition codes for it
3155 if that's what the previous thing was. */
3161 register rtx set
= single_set (insn
);
3163 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3164 delete_computation (insn
);
3167 /* Delete INSN and recursively delete insns that compute values used only
3168 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3169 If we are running before flow.c, we need do nothing since flow.c will
3170 delete dead code. We also can't know if the registers being used are
3171 dead or not at this point.
3173 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3174 nothing other than set a register that dies in this insn, we can delete
3177 On machines with CC0, if CC0 is used in this insn, we may be able to
3178 delete the insn that set it. */
3181 delete_computation (insn
)
3187 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
3189 rtx prev
= prev_nonnote_insn (insn
);
3190 /* We assume that at this stage
3191 CC's are always set explicitly
3192 and always immediately before the jump that
3193 will use them. So if the previous insn
3194 exists to set the CC's, delete it
3195 (unless it performs auto-increments, etc.). */
3196 if (prev
&& GET_CODE (prev
) == INSN
3197 && sets_cc0_p (PATTERN (prev
)))
3199 if (sets_cc0_p (PATTERN (prev
)) > 0
3200 && !FIND_REG_INC_NOTE (prev
, NULL_RTX
))
3201 delete_computation (prev
);
3203 /* Otherwise, show that cc0 won't be used. */
3204 REG_NOTES (prev
) = gen_rtx (EXPR_LIST
, REG_UNUSED
,
3205 cc0_rtx
, REG_NOTES (prev
));
3210 for (note
= REG_NOTES (insn
); note
; note
= next
)
3214 next
= XEXP (note
, 1);
3216 if (REG_NOTE_KIND (note
) != REG_DEAD
3217 /* Verify that the REG_NOTE is legitimate. */
3218 || GET_CODE (XEXP (note
, 0)) != REG
)
3221 for (our_prev
= prev_nonnote_insn (insn
);
3222 our_prev
&& GET_CODE (our_prev
) == INSN
;
3223 our_prev
= prev_nonnote_insn (our_prev
))
3225 /* If we reach a SEQUENCE, it is too complex to try to
3226 do anything with it, so give up. */
3227 if (GET_CODE (PATTERN (our_prev
)) == SEQUENCE
)
3230 if (GET_CODE (PATTERN (our_prev
)) == USE
3231 && GET_CODE (XEXP (PATTERN (our_prev
), 0)) == INSN
)
3232 /* reorg creates USEs that look like this. We leave them
3233 alone because reorg needs them for its own purposes. */
3236 if (reg_set_p (XEXP (note
, 0), PATTERN (our_prev
)))
3238 if (FIND_REG_INC_NOTE (our_prev
, NULL_RTX
))
3241 if (GET_CODE (PATTERN (our_prev
)) == PARALLEL
)
3243 /* If we find a SET of something else, we can't
3248 for (i
= 0; i
< XVECLEN (PATTERN (our_prev
), 0); i
++)
3250 rtx part
= XVECEXP (PATTERN (our_prev
), 0, i
);
3252 if (GET_CODE (part
) == SET
3253 && SET_DEST (part
) != XEXP (note
, 0))
3257 if (i
== XVECLEN (PATTERN (our_prev
), 0))
3258 delete_computation (our_prev
);
3260 else if (GET_CODE (PATTERN (our_prev
)) == SET
3261 && SET_DEST (PATTERN (our_prev
)) == XEXP (note
, 0))
3262 delete_computation (our_prev
);
3267 /* If OUR_PREV references the register that dies here, it is an
3268 additional use. Hence any prior SET isn't dead. However, this
3269 insn becomes the new place for the REG_DEAD note. */
3270 if (reg_overlap_mentioned_p (XEXP (note
, 0),
3271 PATTERN (our_prev
)))
3273 XEXP (note
, 1) = REG_NOTES (our_prev
);
3274 REG_NOTES (our_prev
) = note
;
3283 /* Delete insn INSN from the chain of insns and update label ref counts.
3284 May delete some following insns as a consequence; may even delete
3285 a label elsewhere and insns that follow it.
3287 Returns the first insn after INSN that was not deleted. */
3293 register rtx next
= NEXT_INSN (insn
);
3294 register rtx prev
= PREV_INSN (insn
);
3295 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
3296 register int dont_really_delete
= 0;
3298 while (next
&& INSN_DELETED_P (next
))
3299 next
= NEXT_INSN (next
);
3301 /* This insn is already deleted => return first following nondeleted. */
3302 if (INSN_DELETED_P (insn
))
3305 /* Don't delete user-declared labels. Convert them to special NOTEs
3307 if (was_code_label
&& LABEL_NAME (insn
) != 0
3308 && optimize
&& ! dont_really_delete
)
3310 PUT_CODE (insn
, NOTE
);
3311 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
3312 NOTE_SOURCE_FILE (insn
) = 0;
3313 dont_really_delete
= 1;
3316 /* Mark this insn as deleted. */
3317 INSN_DELETED_P (insn
) = 1;
3319 /* If this is an unconditional jump, delete it from the jump chain. */
3320 if (simplejump_p (insn
))
3321 delete_from_jump_chain (insn
);
3323 /* If instruction is followed by a barrier,
3324 delete the barrier too. */
3326 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
3328 INSN_DELETED_P (next
) = 1;
3329 next
= NEXT_INSN (next
);
3332 /* Patch out INSN (and the barrier if any) */
3334 if (optimize
&& ! dont_really_delete
)
3338 NEXT_INSN (prev
) = next
;
3339 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
3340 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
3341 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
3346 PREV_INSN (next
) = prev
;
3347 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
3348 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
3351 if (prev
&& NEXT_INSN (prev
) == 0)
3352 set_last_insn (prev
);
3355 /* If deleting a jump, decrement the count of the label,
3356 and delete the label if it is now unused. */
3358 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
3359 if (--LABEL_NUSES (JUMP_LABEL (insn
)) == 0)
3361 /* This can delete NEXT or PREV,
3362 either directly if NEXT is JUMP_LABEL (INSN),
3363 or indirectly through more levels of jumps. */
3364 delete_insn (JUMP_LABEL (insn
));
3365 /* I feel a little doubtful about this loop,
3366 but I see no clean and sure alternative way
3367 to find the first insn after INSN that is not now deleted.
3368 I hope this works. */
3369 while (next
&& INSN_DELETED_P (next
))
3370 next
= NEXT_INSN (next
);
3374 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
3375 prev
= PREV_INSN (prev
);
3377 /* If INSN was a label and a dispatch table follows it,
3378 delete the dispatch table. The tablejump must have gone already.
3379 It isn't useful to fall through into a table. */
3382 && NEXT_INSN (insn
) != 0
3383 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
3384 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
3385 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
3386 next
= delete_insn (NEXT_INSN (insn
));
3388 /* If INSN was a label, delete insns following it if now unreachable. */
3390 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
3392 register RTX_CODE code
;
3394 && (GET_RTX_CLASS (code
= GET_CODE (next
)) == 'i'
3396 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
3399 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
3400 next
= NEXT_INSN (next
);
3401 /* Keep going past other deleted labels to delete what follows. */
3402 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
3403 next
= NEXT_INSN (next
);
3405 /* Note: if this deletes a jump, it can cause more
3406 deletion of unreachable code, after a different label.
3407 As long as the value from this recursive call is correct,
3408 this invocation functions correctly. */
3409 next
= delete_insn (next
);
3416 /* Advance from INSN till reaching something not deleted
3417 then return that. May return INSN itself. */
3420 next_nondeleted_insn (insn
)
3423 while (INSN_DELETED_P (insn
))
3424 insn
= NEXT_INSN (insn
);
3428 /* Delete a range of insns from FROM to TO, inclusive.
3429 This is for the sake of peephole optimization, so assume
3430 that whatever these insns do will still be done by a new
3431 peephole insn that will replace them. */
3434 delete_for_peephole (from
, to
)
3435 register rtx from
, to
;
3437 register rtx insn
= from
;
3441 register rtx next
= NEXT_INSN (insn
);
3442 register rtx prev
= PREV_INSN (insn
);
3444 if (GET_CODE (insn
) != NOTE
)
3446 INSN_DELETED_P (insn
) = 1;
3448 /* Patch this insn out of the chain. */
3449 /* We don't do this all at once, because we
3450 must preserve all NOTEs. */
3452 NEXT_INSN (prev
) = next
;
3455 PREV_INSN (next
) = prev
;
3463 /* Note that if TO is an unconditional jump
3464 we *do not* delete the BARRIER that follows,
3465 since the peephole that replaces this sequence
3466 is also an unconditional jump in that case. */
3469 /* Invert the condition of the jump JUMP, and make it jump
3470 to label NLABEL instead of where it jumps now. */
3473 invert_jump (jump
, nlabel
)
3476 /* We have to either invert the condition and change the label or
3477 do neither. Either operation could fail. We first try to invert
3478 the jump. If that succeeds, we try changing the label. If that fails,
3479 we invert the jump back to what it was. */
3481 if (! invert_exp (PATTERN (jump
), jump
))
3484 if (redirect_jump (jump
, nlabel
))
3487 if (! invert_exp (PATTERN (jump
), jump
))
3488 /* This should just be putting it back the way it was. */
3494 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3496 Return 1 if we can do so, 0 if we cannot find a way to do so that
3497 matches a pattern. */
3500 invert_exp (x
, insn
)
3504 register RTX_CODE code
;
3508 code
= GET_CODE (x
);
3510 if (code
== IF_THEN_ELSE
)
3512 register rtx comp
= XEXP (x
, 0);
3515 /* We can do this in two ways: The preferable way, which can only
3516 be done if this is not an integer comparison, is to reverse
3517 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3518 of the IF_THEN_ELSE. If we can't do either, fail. */
3520 if (can_reverse_comparison_p (comp
, insn
)
3521 && validate_change (insn
, &XEXP (x
, 0),
3522 gen_rtx (reverse_condition (GET_CODE (comp
)),
3523 GET_MODE (comp
), XEXP (comp
, 0),
3524 XEXP (comp
, 1)), 0))
3528 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
3529 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
3530 return apply_change_group ();
3533 fmt
= GET_RTX_FORMAT (code
);
3534 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3537 if (! invert_exp (XEXP (x
, i
), insn
))
3542 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3543 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
3551 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3552 If the old jump target label is unused as a result,
3553 it and the code following it may be deleted.
3555 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3558 The return value will be 1 if the change was made, 0 if it wasn't (this
3559 can only occur for NLABEL == 0). */
3562 redirect_jump (jump
, nlabel
)
3565 register rtx olabel
= JUMP_LABEL (jump
);
3567 if (nlabel
== olabel
)
3570 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
3573 /* If this is an unconditional branch, delete it from the jump_chain of
3574 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3575 have UID's in range and JUMP_CHAIN is valid). */
3576 if (jump_chain
&& (simplejump_p (jump
)
3577 || GET_CODE (PATTERN (jump
)) == RETURN
))
3579 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
3581 delete_from_jump_chain (jump
);
3582 if (label_index
< max_jump_chain
3583 && INSN_UID (jump
) < max_jump_chain
)
3585 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
3586 jump_chain
[label_index
] = jump
;
3590 JUMP_LABEL (jump
) = nlabel
;
3592 ++LABEL_NUSES (nlabel
);
3594 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
3595 delete_insn (olabel
);
3600 /* Delete the instruction JUMP from any jump chain it might be on. */
3603 delete_from_jump_chain (jump
)
3607 rtx olabel
= JUMP_LABEL (jump
);
3609 /* Handle unconditional jumps. */
3610 if (jump_chain
&& olabel
!= 0
3611 && INSN_UID (olabel
) < max_jump_chain
3612 && simplejump_p (jump
))
3613 index
= INSN_UID (olabel
);
3614 /* Handle return insns. */
3615 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
3619 if (jump_chain
[index
] == jump
)
3620 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
3625 for (insn
= jump_chain
[index
];
3627 insn
= jump_chain
[INSN_UID (insn
)])
3628 if (jump_chain
[INSN_UID (insn
)] == jump
)
3630 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
3636 /* If NLABEL is nonzero, throughout the rtx at LOC,
3637 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3638 zero, alter (RETURN) to (LABEL_REF NLABEL).
3640 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3641 validity with validate_change. Convert (set (pc) (label_ref olabel))
3644 Return 0 if we found a change we would like to make but it is invalid.
3645 Otherwise, return 1. */
3648 redirect_exp (loc
, olabel
, nlabel
, insn
)
3653 register rtx x
= *loc
;
3654 register RTX_CODE code
= GET_CODE (x
);
3658 if (code
== LABEL_REF
)
3660 if (XEXP (x
, 0) == olabel
)
3663 XEXP (x
, 0) = nlabel
;
3665 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3669 else if (code
== RETURN
&& olabel
== 0)
3671 x
= gen_rtx (LABEL_REF
, VOIDmode
, nlabel
);
3672 if (loc
== &PATTERN (insn
))
3673 x
= gen_rtx (SET
, VOIDmode
, pc_rtx
, x
);
3674 return validate_change (insn
, loc
, x
, 0);
3677 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
3678 && GET_CODE (SET_SRC (x
)) == LABEL_REF
3679 && XEXP (SET_SRC (x
), 0) == olabel
)
3680 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3682 fmt
= GET_RTX_FORMAT (code
);
3683 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3686 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
3691 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3692 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
3700 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3702 If the old jump target label (before the dispatch table) becomes unused,
3703 it and the dispatch table may be deleted. In that case, find the insn
3704 before the jump references that label and delete it and logical successors
3708 redirect_tablejump (jump
, nlabel
)
3711 register rtx olabel
= JUMP_LABEL (jump
);
3713 /* Add this jump to the jump_chain of NLABEL. */
3714 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
3715 && INSN_UID (jump
) < max_jump_chain
)
3717 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
3718 jump_chain
[INSN_UID (nlabel
)] = jump
;
3721 PATTERN (jump
) = gen_jump (nlabel
);
3722 JUMP_LABEL (jump
) = nlabel
;
3723 ++LABEL_NUSES (nlabel
);
3724 INSN_CODE (jump
) = -1;
3726 if (--LABEL_NUSES (olabel
) == 0)
3728 delete_labelref_insn (jump
, olabel
, 0);
3729 delete_insn (olabel
);
3733 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3734 If we found one, delete it and then delete this insn if DELETE_THIS is
3735 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3738 delete_labelref_insn (insn
, label
, delete_this
)
3745 if (GET_CODE (insn
) != NOTE
3746 && reg_mentioned_p (label
, PATTERN (insn
)))
3757 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
3758 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
3772 /* Like rtx_equal_p except that it considers two REGs as equal
3773 if they renumber to the same value and considers two commutative
3774 operations to be the same if the order of the operands has been
3778 rtx_renumbered_equal_p (x
, y
)
3782 register RTX_CODE code
= GET_CODE (x
);
3788 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
3789 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
3790 && GET_CODE (SUBREG_REG (y
)) == REG
)))
3792 int reg_x
= -1, reg_y
= -1;
3793 int word_x
= 0, word_y
= 0;
3795 if (GET_MODE (x
) != GET_MODE (y
))
3798 /* If we haven't done any renumbering, don't
3799 make any assumptions. */
3800 if (reg_renumber
== 0)
3801 return rtx_equal_p (x
, y
);
3805 reg_x
= REGNO (SUBREG_REG (x
));
3806 word_x
= SUBREG_WORD (x
);
3808 if (reg_renumber
[reg_x
] >= 0)
3810 reg_x
= reg_renumber
[reg_x
] + word_x
;
3818 if (reg_renumber
[reg_x
] >= 0)
3819 reg_x
= reg_renumber
[reg_x
];
3822 if (GET_CODE (y
) == SUBREG
)
3824 reg_y
= REGNO (SUBREG_REG (y
));
3825 word_y
= SUBREG_WORD (y
);
3827 if (reg_renumber
[reg_y
] >= 0)
3829 reg_y
= reg_renumber
[reg_y
];
3837 if (reg_renumber
[reg_y
] >= 0)
3838 reg_y
= reg_renumber
[reg_y
];
3841 return reg_x
>= 0 && reg_x
== reg_y
&& word_x
== word_y
;
3844 /* Now we have disposed of all the cases
3845 in which different rtx codes can match. */
3846 if (code
!= GET_CODE (y
))
3858 return INTVAL (x
) == INTVAL (y
);
3861 /* We can't assume nonlocal labels have their following insns yet. */
3862 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
3863 return XEXP (x
, 0) == XEXP (y
, 0);
3865 /* Two label-refs are equivalent if they point at labels
3866 in the same position in the instruction stream. */
3867 return (next_real_insn (XEXP (x
, 0))
3868 == next_real_insn (XEXP (y
, 0)));
3871 return XSTR (x
, 0) == XSTR (y
, 0);
3874 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3876 if (GET_MODE (x
) != GET_MODE (y
))
3879 /* For commutative operations, the RTX match if the operand match in any
3880 order. Also handle the simple binary and unary cases without a loop. */
3881 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
3882 return ((rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
3883 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)))
3884 || (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 1))
3885 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 0))));
3886 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
3887 return (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
3888 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)));
3889 else if (GET_RTX_CLASS (code
) == '1')
3890 return rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0));
3892 /* Compare the elements. If any pair of corresponding elements
3893 fail to match, return 0 for the whole things. */
3895 fmt
= GET_RTX_FORMAT (code
);
3896 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3902 if (XWINT (x
, i
) != XWINT (y
, i
))
3907 if (XINT (x
, i
) != XINT (y
, i
))
3912 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
3917 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
3922 if (XEXP (x
, i
) != XEXP (y
, i
))
3929 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
3931 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
3932 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
3943 /* If X is a hard register or equivalent to one or a subregister of one,
3944 return the hard register number. If X is a pseudo register that was not
3945 assigned a hard register, return the pseudo register number. Otherwise,
3946 return -1. Any rtx is valid for X. */
3952 if (GET_CODE (x
) == REG
)
3954 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
3955 return reg_renumber
[REGNO (x
)];
3958 if (GET_CODE (x
) == SUBREG
)
3960 int base
= true_regnum (SUBREG_REG (x
));
3961 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
3962 return SUBREG_WORD (x
) + base
;
3967 /* Optimize code of the form:
3969 for (x = a[i]; x; ...)
3971 for (x = a[i]; x; ...)
3975 Loop optimize will change the above code into
3979 { ...; if (! (x = ...)) break; }
3982 { ...; if (! (x = ...)) break; }
3985 In general, if the first test fails, the program can branch
3986 directly to `foo' and skip the second try which is doomed to fail.
3987 We run this after loop optimization and before flow analysis. */
3989 /* When comparing the insn patterns, we track the fact that different
3990 pseudo-register numbers may have been used in each computation.
3991 The following array stores an equivalence -- same_regs[I] == J means
3992 that pseudo register I was used in the first set of tests in a context
3993 where J was used in the second set. We also count the number of such
3994 pending equivalences. If nonzero, the expressions really aren't the
3997 static int *same_regs
;
3999 static int num_same_regs
;
4001 /* Track any registers modified between the target of the first jump and
4002 the second jump. They never compare equal. */
4004 static char *modified_regs
;
4006 /* Record if memory was modified. */
4008 static int modified_mem
;
4010 /* Called via note_stores on each insn between the target of the first
4011 branch and the second branch. It marks any changed registers. */
4014 mark_modified_reg (dest
, x
)
4020 if (GET_CODE (dest
) == SUBREG
)
4021 dest
= SUBREG_REG (dest
);
4023 if (GET_CODE (dest
) == MEM
)
4026 if (GET_CODE (dest
) != REG
)
4029 regno
= REGNO (dest
);
4030 if (regno
>= FIRST_PSEUDO_REGISTER
)
4031 modified_regs
[regno
] = 1;
4033 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
4034 modified_regs
[regno
+ i
] = 1;
4037 /* F is the first insn in the chain of insns. */
4040 thread_jumps (f
, max_reg
, flag_before_loop
)
4043 int flag_before_loop
;
4045 /* Basic algorithm is to find a conditional branch,
4046 the label it may branch to, and the branch after
4047 that label. If the two branches test the same condition,
4048 walk back from both branch paths until the insn patterns
4049 differ, or code labels are hit. If we make it back to
4050 the target of the first branch, then we know that the first branch
4051 will either always succeed or always fail depending on the relative
4052 senses of the two branches. So adjust the first branch accordingly
4055 rtx label
, b1
, b2
, t1
, t2
;
4056 enum rtx_code code1
, code2
;
4057 rtx b1op0
, b1op1
, b2op0
, b2op1
;
4062 /* Allocate register tables and quick-reset table. */
4063 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
4064 same_regs
= (int *) alloca (max_reg
* sizeof (int));
4065 all_reset
= (int *) alloca (max_reg
* sizeof (int));
4066 for (i
= 0; i
< max_reg
; i
++)
4073 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
4075 /* Get to a candidate branch insn. */
4076 if (GET_CODE (b1
) != JUMP_INSN
4077 || ! condjump_p (b1
) || simplejump_p (b1
)
4078 || JUMP_LABEL (b1
) == 0)
4081 bzero (modified_regs
, max_reg
* sizeof (char));
4084 bcopy ((char *) all_reset
, (char *) same_regs
,
4085 max_reg
* sizeof (int));
4088 label
= JUMP_LABEL (b1
);
4090 /* Look for a branch after the target. Record any registers and
4091 memory modified between the target and the branch. Stop when we
4092 get to a label since we can't know what was changed there. */
4093 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
4095 if (GET_CODE (b2
) == CODE_LABEL
)
4098 else if (GET_CODE (b2
) == JUMP_INSN
)
4100 /* If this is an unconditional jump and is the only use of
4101 its target label, we can follow it. */
4102 if (simplejump_p (b2
)
4103 && JUMP_LABEL (b2
) != 0
4104 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
4106 b2
= JUMP_LABEL (b2
);
4113 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
4116 if (GET_CODE (b2
) == CALL_INSN
)
4119 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
4120 if (call_used_regs
[i
] && ! fixed_regs
[i
]
4121 && i
!= STACK_POINTER_REGNUM
4122 && i
!= FRAME_POINTER_REGNUM
4123 && i
!= HARD_FRAME_POINTER_REGNUM
4124 && i
!= ARG_POINTER_REGNUM
)
4125 modified_regs
[i
] = 1;
4128 note_stores (PATTERN (b2
), mark_modified_reg
);
4131 /* Check the next candidate branch insn from the label
4134 || GET_CODE (b2
) != JUMP_INSN
4136 || ! condjump_p (b2
)
4137 || simplejump_p (b2
))
4140 /* Get the comparison codes and operands, reversing the
4141 codes if appropriate. If we don't have comparison codes,
4142 we can't do anything. */
4143 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
4144 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
4145 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
4146 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
4147 code1
= reverse_condition (code1
);
4149 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
4150 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
4151 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
4152 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
4153 code2
= reverse_condition (code2
);
4155 /* If they test the same things and knowing that B1 branches
4156 tells us whether or not B2 branches, check if we
4157 can thread the branch. */
4158 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
4159 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
4160 && (comparison_dominates_p (code1
, code2
)
4161 || comparison_dominates_p (code1
, reverse_condition (code2
))))
4163 t1
= prev_nonnote_insn (b1
);
4164 t2
= prev_nonnote_insn (b2
);
4166 while (t1
!= 0 && t2
!= 0)
4170 /* We have reached the target of the first branch.
4171 If there are no pending register equivalents,
4172 we know that this branch will either always
4173 succeed (if the senses of the two branches are
4174 the same) or always fail (if not). */
4177 if (num_same_regs
!= 0)
4180 if (comparison_dominates_p (code1
, code2
))
4181 new_label
= JUMP_LABEL (b2
);
4183 new_label
= get_label_after (b2
);
4185 if (JUMP_LABEL (b1
) != new_label
)
4187 rtx prev
= PREV_INSN (new_label
);
4189 if (flag_before_loop
4190 && NOTE_LINE_NUMBER (prev
) == NOTE_INSN_LOOP_BEG
)
4192 /* Don't thread to the loop label. If a loop
4193 label is reused, loop optimization will
4194 be disabled for that loop. */
4195 new_label
= gen_label_rtx ();
4196 emit_label_after (new_label
, PREV_INSN (prev
));
4198 changed
|= redirect_jump (b1
, new_label
);
4203 /* If either of these is not a normal insn (it might be
4204 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4205 have already been skipped above.) Similarly, fail
4206 if the insns are different. */
4207 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
4208 || recog_memoized (t1
) != recog_memoized (t2
)
4209 || ! rtx_equal_for_thread_p (PATTERN (t1
),
4213 t1
= prev_nonnote_insn (t1
);
4214 t2
= prev_nonnote_insn (t2
);
4221 /* This is like RTX_EQUAL_P except that it knows about our handling of
4222 possibly equivalent registers and knows to consider volatile and
4223 modified objects as not equal.
4225 YINSN is the insn containing Y. */
4228 rtx_equal_for_thread_p (x
, y
, yinsn
)
4234 register enum rtx_code code
;
4237 code
= GET_CODE (x
);
4238 /* Rtx's of different codes cannot be equal. */
4239 if (code
!= GET_CODE (y
))
4242 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4243 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4245 if (GET_MODE (x
) != GET_MODE (y
))
4248 /* For commutative operations, the RTX match if the operand match in any
4249 order. Also handle the simple binary and unary cases without a loop. */
4250 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4251 return ((rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4252 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
))
4253 || (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 1), yinsn
)
4254 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 0), yinsn
)));
4255 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4256 return (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4257 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
));
4258 else if (GET_RTX_CLASS (code
) == '1')
4259 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4261 /* Handle special-cases first. */
4265 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
4268 /* If neither is user variable or hard register, check for possible
4270 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
4271 || REGNO (x
) < FIRST_PSEUDO_REGISTER
4272 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
4275 if (same_regs
[REGNO (x
)] == -1)
4277 same_regs
[REGNO (x
)] = REGNO (y
);
4280 /* If this is the first time we are seeing a register on the `Y'
4281 side, see if it is the last use. If not, we can't thread the
4282 jump, so mark it as not equivalent. */
4283 if (regno_last_uid
[REGNO (y
)] != INSN_UID (yinsn
))
4289 return (same_regs
[REGNO (x
)] == REGNO (y
));
4294 /* If memory modified or either volatile, not equivalent.
4295 Else, check address. */
4296 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4299 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4302 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4308 /* Cancel a pending `same_regs' if setting equivalenced registers.
4309 Then process source. */
4310 if (GET_CODE (SET_DEST (x
)) == REG
4311 && GET_CODE (SET_DEST (y
)) == REG
)
4313 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
4315 same_regs
[REGNO (SET_DEST (x
))] = -1;
4318 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
4322 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
4325 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
4328 return XEXP (x
, 0) == XEXP (y
, 0);
4331 return XSTR (x
, 0) == XSTR (y
, 0);
4337 fmt
= GET_RTX_FORMAT (code
);
4338 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4343 if (XWINT (x
, i
) != XWINT (y
, i
))
4349 if (XINT (x
, i
) != XINT (y
, i
))
4355 /* Two vectors must have the same length. */
4356 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4359 /* And the corresponding elements must match. */
4360 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4361 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
4362 XVECEXP (y
, i
, j
), yinsn
) == 0)
4367 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
4373 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4378 /* These are just backpointers, so they don't matter. */
4384 /* It is believed that rtx's at this level will never
4385 contain anything but integers and other rtx's,
4386 except for within LABEL_REFs and SYMBOL_REFs. */