1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-94, 1995 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"
58 #include "insn-config.h"
59 #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 /* Also delete insns to store bit fields if they are no-ops. */
520 /* Not worth the hair to detect this in the big-endian case. */
521 else if (! BYTES_BIG_ENDIAN
522 && 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
))))
533 /* If we haven't yet gotten to reload and we have just run regscan,
534 delete any insn that sets a register that isn't used elsewhere.
535 This helps some of the optimizations below by having less insns
536 being jumped around. */
538 if (! reload_completed
&& after_regscan
)
539 for (insn
= f
; insn
; insn
= next
)
541 rtx set
= single_set (insn
);
543 next
= NEXT_INSN (insn
);
545 if (set
&& GET_CODE (SET_DEST (set
)) == REG
546 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
547 && regno_first_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
)
548 /* We use regno_last_note_uid so as not to delete the setting
549 of a reg that's used in notes. A subsequent optimization
550 might arrange to use that reg for real. */
551 && regno_last_note_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
)
552 && ! side_effects_p (SET_SRC (set
))
553 && ! find_reg_note (insn
, REG_RETVAL
, 0))
557 /* Now iterate optimizing jumps until nothing changes over one pass. */
563 for (insn
= f
; insn
; insn
= next
)
566 rtx temp
, temp1
, temp2
, temp3
, temp4
, temp5
, temp6
;
568 int this_is_simplejump
, this_is_condjump
, reversep
;
569 int this_is_condjump_in_parallel
;
571 /* If NOT the first iteration, if this is the last jump pass
572 (just before final), do the special peephole optimizations.
573 Avoiding the first iteration gives ordinary jump opts
574 a chance to work before peephole opts. */
576 if (reload_completed
&& !first
&& !flag_no_peephole
)
577 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
581 /* That could have deleted some insns after INSN, so check now
582 what the following insn is. */
584 next
= NEXT_INSN (insn
);
586 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
587 jump. Try to optimize by duplicating the loop exit test if so.
588 This is only safe immediately after regscan, because it uses
589 the values of regno_first_uid and regno_last_uid. */
590 if (after_regscan
&& GET_CODE (insn
) == NOTE
591 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
592 && (temp1
= next_nonnote_insn (insn
)) != 0
593 && simplejump_p (temp1
))
595 temp
= PREV_INSN (insn
);
596 if (duplicate_loop_exit_test (insn
))
599 next
= NEXT_INSN (temp
);
604 if (GET_CODE (insn
) != JUMP_INSN
)
607 this_is_simplejump
= simplejump_p (insn
);
608 this_is_condjump
= condjump_p (insn
);
609 this_is_condjump_in_parallel
= condjump_in_parallel_p (insn
);
611 /* Tension the labels in dispatch tables. */
613 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
614 changed
|= tension_vector_labels (PATTERN (insn
), 0);
615 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
616 changed
|= tension_vector_labels (PATTERN (insn
), 1);
618 /* If a dispatch table always goes to the same place,
619 get rid of it and replace the insn that uses it. */
621 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
622 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
625 rtx pat
= PATTERN (insn
);
626 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
627 int len
= XVECLEN (pat
, diff_vec_p
);
628 rtx dispatch
= prev_real_insn (insn
);
630 for (i
= 0; i
< len
; i
++)
631 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
632 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
636 && GET_CODE (dispatch
) == JUMP_INSN
637 && JUMP_LABEL (dispatch
) != 0
638 /* Don't mess with a casesi insn. */
639 && !(GET_CODE (PATTERN (dispatch
)) == SET
640 && (GET_CODE (SET_SRC (PATTERN (dispatch
)))
642 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
644 redirect_tablejump (dispatch
,
645 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
650 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
652 /* If a jump references the end of the function, try to turn
653 it into a RETURN insn, possibly a conditional one. */
654 if (JUMP_LABEL (insn
)
655 && (next_active_insn (JUMP_LABEL (insn
)) == 0
656 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn
))))
658 changed
|= redirect_jump (insn
, NULL_RTX
);
660 /* Detect jump to following insn. */
661 if (reallabelprev
== insn
&& condjump_p (insn
))
663 next
= next_real_insn (JUMP_LABEL (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 /* Try to use a conditional move (if the target has them), or a
991 store-flag insn. The general case is:
993 1) x = a; if (...) x = b; and
996 If the jump would be faster, the machine should not have defined
997 the movcc or scc insns!. These cases are often made by the
998 previous optimization.
1000 The second case is treated as x = x; if (...) x = b;.
1002 INSN here is the jump around the store. We set:
1004 TEMP to the "x = b;" insn.
1007 TEMP3 to A (X in the second case).
1008 TEMP4 to the condition being tested.
1009 TEMP5 to the earliest insn used to find the condition. */
1011 if (/* We can't do this after reload has completed. */
1013 && this_is_condjump
&& ! this_is_simplejump
1014 /* Set TEMP to the "x = b;" insn. */
1015 && (temp
= next_nonnote_insn (insn
)) != 0
1016 && GET_CODE (temp
) == INSN
1017 && GET_CODE (PATTERN (temp
)) == SET
1018 && GET_CODE (temp1
= SET_DEST (PATTERN (temp
))) == REG
1019 #ifdef SMALL_REGISTER_CLASSES
1020 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
1022 && (GET_CODE (temp2
= SET_SRC (PATTERN (temp
))) == REG
1023 || GET_CODE (temp2
) == SUBREG
1024 /* ??? How about floating point constants? */
1025 || GET_CODE (temp2
) == CONST_INT
)
1026 /* Allow either form, but prefer the former if both apply.
1027 There is no point in using the old value of TEMP1 if
1028 it is a register, since cse will alias them. It can
1029 lose if the old value were a hard register since CSE
1030 won't replace hard registers. */
1031 && (((temp3
= reg_set_last (temp1
, insn
)) != 0)
1032 /* Make the latter case look like x = x; if (...) x = b; */
1033 || (temp3
= temp1
, 1))
1034 /* INSN must either branch to the insn after TEMP or the insn
1035 after TEMP must branch to the same place as INSN. */
1036 && (reallabelprev
== temp
1037 || ((temp4
= next_active_insn (temp
)) != 0
1038 && simplejump_p (temp4
)
1039 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
1040 && (temp4
= get_condition (insn
, &temp5
)) != 0
1041 /* We must be comparing objects whose modes imply the size.
1042 We could handle BLKmode if (1) emit_store_flag could
1043 and (2) we could find the size reliably. */
1044 && GET_MODE (XEXP (temp4
, 0)) != BLKmode
1045 /* No point in doing any of this if branches are cheap or we
1046 don't have conditional moves. */
1047 && (BRANCH_COST
>= 2
1048 #ifdef HAVE_conditional_move
1053 /* If the previous insn sets CC0 and something else, we can't
1054 do this since we are going to delete that insn. */
1056 && ! ((temp6
= prev_nonnote_insn (insn
)) != 0
1057 && GET_CODE (temp6
) == INSN
1058 && (sets_cc0_p (PATTERN (temp6
)) == -1
1059 || (sets_cc0_p (PATTERN (temp6
)) == 1
1060 && FIND_REG_INC_NOTE (temp6
, NULL_RTX
))))
1064 #ifdef HAVE_conditional_move
1065 /* First try a conditional move. */
1067 enum rtx_code code
= GET_CODE (temp4
);
1069 rtx cond0
, cond1
, aval
, bval
;
1072 /* Copy the compared variables into cond0 and cond1, so that
1073 any side effects performed in or after the old comparison,
1074 will not affect our compare which will come later. */
1075 /* ??? Is it possible to just use the comparison in the jump
1076 insn? After all, we're going to delete it. We'd have
1077 to modify emit_conditional_move to take a comparison rtx
1078 instead or write a new function. */
1079 cond0
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 0)));
1080 /* We want the target to be able to simplify comparisons with
1081 zero (and maybe other constants as well), so don't create
1082 pseudos for them. There's no need to either. */
1083 if (GET_CODE (XEXP (temp4
, 1)) == CONST_INT
1084 || GET_CODE (XEXP (temp4
, 1)) == CONST_DOUBLE
)
1085 cond1
= XEXP (temp4
, 1);
1087 cond1
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 1)));
1093 target
= emit_conditional_move (var
, code
,
1094 cond0
, cond1
, VOIDmode
,
1095 aval
, bval
, GET_MODE (var
),
1096 (code
== LTU
|| code
== GEU
1097 || code
== LEU
|| code
== GTU
));
1103 /* Save the conditional move sequence but don't emit it
1104 yet. On some machines, like the alpha, it is possible
1105 that temp5 == insn, so next generate the sequence that
1106 saves the compared values and then emit both
1107 sequences ensuring seq1 occurs before seq2. */
1108 seq2
= get_insns ();
1111 /* Now that we can't fail, generate the copy insns that
1112 preserve the compared values. */
1114 emit_move_insn (cond0
, XEXP (temp4
, 0));
1115 if (cond1
!= XEXP (temp4
, 1))
1116 emit_move_insn (cond1
, XEXP (temp4
, 1));
1117 seq1
= get_insns ();
1120 emit_insns_before (seq1
, temp5
);
1121 emit_insns_before (seq2
, insn
);
1123 /* ??? We can also delete the insn that sets X to A.
1124 Flow will do it too though. */
1126 next
= NEXT_INSN (insn
);
1136 /* That didn't work, try a store-flag insn.
1138 We further divide the cases into:
1140 1) x = a; if (...) x = b; and either A or B is zero,
1141 2) if (...) x = 0; and jumps are expensive,
1142 3) x = a; if (...) x = b; and A and B are constants where all
1143 the set bits in A are also set in B and jumps are expensive,
1144 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1146 5) if (...) x = b; if jumps are even more expensive. */
1148 if (GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
1149 && ((GET_CODE (temp3
) == CONST_INT
)
1150 /* Make the latter case look like
1151 x = x; if (...) x = 0; */
1154 && temp2
== const0_rtx
)
1155 || BRANCH_COST
>= 3)))
1156 /* If B is zero, OK; if A is zero, can only do (1) if we
1157 can reverse the condition. See if (3) applies possibly
1158 by reversing the condition. Prefer reversing to (4) when
1159 branches are very expensive. */
1160 && ((reversep
= 0, temp2
== const0_rtx
)
1161 || (temp3
== const0_rtx
1162 && (reversep
= can_reverse_comparison_p (temp4
, insn
)))
1163 || (BRANCH_COST
>= 2
1164 && GET_CODE (temp2
) == CONST_INT
1165 && GET_CODE (temp3
) == CONST_INT
1166 && ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp2
)
1167 || ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp3
)
1168 && (reversep
= can_reverse_comparison_p (temp4
,
1170 || BRANCH_COST
>= 3)
1173 enum rtx_code code
= GET_CODE (temp4
);
1174 rtx uval
, cval
, var
= temp1
;
1178 /* If necessary, reverse the condition. */
1180 code
= reverse_condition (code
), uval
= temp2
, cval
= temp3
;
1182 uval
= temp3
, cval
= temp2
;
1184 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1185 is the constant 1, it is best to just compute the result
1186 directly. If UVAL is constant and STORE_FLAG_VALUE
1187 includes all of its bits, it is best to compute the flag
1188 value unnormalized and `and' it with UVAL. Otherwise,
1189 normalize to -1 and `and' with UVAL. */
1190 normalizep
= (cval
!= const0_rtx
? -1
1191 : (uval
== const1_rtx
? 1
1192 : (GET_CODE (uval
) == CONST_INT
1193 && (INTVAL (uval
) & ~STORE_FLAG_VALUE
) == 0)
1196 /* We will be putting the store-flag insn immediately in
1197 front of the comparison that was originally being done,
1198 so we know all the variables in TEMP4 will be valid.
1199 However, this might be in front of the assignment of
1200 A to VAR. If it is, it would clobber the store-flag
1201 we will be emitting.
1203 Therefore, emit into a temporary which will be copied to
1204 VAR immediately after TEMP. */
1207 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
1208 XEXP (temp4
, 0), XEXP (temp4
, 1),
1210 (code
== LTU
|| code
== LEU
1211 || code
== GEU
|| code
== GTU
),
1221 /* Put the store-flag insns in front of the first insn
1222 used to compute the condition to ensure that we
1223 use the same values of them as the current
1224 comparison. However, the remainder of the insns we
1225 generate will be placed directly in front of the
1226 jump insn, in case any of the pseudos we use
1227 are modified earlier. */
1229 emit_insns_before (seq
, temp5
);
1233 /* Both CVAL and UVAL are non-zero. */
1234 if (cval
!= const0_rtx
&& uval
!= const0_rtx
)
1238 tem1
= expand_and (uval
, target
, NULL_RTX
);
1239 if (GET_CODE (cval
) == CONST_INT
1240 && GET_CODE (uval
) == CONST_INT
1241 && (INTVAL (cval
) & INTVAL (uval
)) == INTVAL (cval
))
1245 tem2
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1246 target
, NULL_RTX
, 0);
1247 tem2
= expand_and (cval
, tem2
,
1248 (GET_CODE (tem2
) == REG
1252 /* If we usually make new pseudos, do so here. This
1253 turns out to help machines that have conditional
1255 /* ??? Conditional moves have already been handled.
1256 This may be obsolete. */
1258 if (flag_expensive_optimizations
)
1261 target
= expand_binop (GET_MODE (var
), ior_optab
,
1265 else if (normalizep
!= 1)
1267 /* We know that either CVAL or UVAL is zero. If
1268 UVAL is zero, negate TARGET and `and' with CVAL.
1269 Otherwise, `and' with UVAL. */
1270 if (uval
== const0_rtx
)
1272 target
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1273 target
, NULL_RTX
, 0);
1277 target
= expand_and (uval
, target
,
1278 (GET_CODE (target
) == REG
1279 && ! preserve_subexpressions_p ()
1280 ? target
: NULL_RTX
));
1283 emit_move_insn (var
, target
);
1287 /* If INSN uses CC0, we must not separate it from the
1288 insn that sets cc0. */
1289 if (reg_mentioned_p (cc0_rtx
, PATTERN (before
)))
1290 before
= prev_nonnote_insn (before
);
1292 emit_insns_before (seq
, before
);
1295 next
= NEXT_INSN (insn
);
1305 /* If branches are expensive, convert
1306 if (foo) bar++; to bar += (foo != 0);
1307 and similarly for "bar--;"
1309 INSN is the conditional branch around the arithmetic. We set:
1311 TEMP is the arithmetic insn.
1312 TEMP1 is the SET doing the arithmetic.
1313 TEMP2 is the operand being incremented or decremented.
1314 TEMP3 to the condition being tested.
1315 TEMP4 to the earliest insn used to find the condition. */
1317 if ((BRANCH_COST
>= 2
1325 && ! reload_completed
1326 && this_is_condjump
&& ! this_is_simplejump
1327 && (temp
= next_nonnote_insn (insn
)) != 0
1328 && (temp1
= single_set (temp
)) != 0
1329 && (temp2
= SET_DEST (temp1
),
1330 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
1331 && GET_CODE (SET_SRC (temp1
)) == PLUS
1332 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1333 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
1334 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
1335 && ! side_effects_p (temp2
)
1336 && ! may_trap_p (temp2
)
1337 /* INSN must either branch to the insn after TEMP or the insn
1338 after TEMP must branch to the same place as INSN. */
1339 && (reallabelprev
== temp
1340 || ((temp3
= next_active_insn (temp
)) != 0
1341 && simplejump_p (temp3
)
1342 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
1343 && (temp3
= get_condition (insn
, &temp4
)) != 0
1344 /* We must be comparing objects whose modes imply the size.
1345 We could handle BLKmode if (1) emit_store_flag could
1346 and (2) we could find the size reliably. */
1347 && GET_MODE (XEXP (temp3
, 0)) != BLKmode
1348 && can_reverse_comparison_p (temp3
, insn
))
1350 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
1351 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
1355 /* It must be the case that TEMP2 is not modified in the range
1356 [TEMP4, INSN). The one exception we make is if the insn
1357 before INSN sets TEMP2 to something which is also unchanged
1358 in that range. In that case, we can move the initialization
1359 into our sequence. */
1361 if ((temp5
= prev_active_insn (insn
)) != 0
1362 && GET_CODE (temp5
) == INSN
1363 && (temp6
= single_set (temp5
)) != 0
1364 && rtx_equal_p (temp2
, SET_DEST (temp6
))
1365 && (CONSTANT_P (SET_SRC (temp6
))
1366 || GET_CODE (SET_SRC (temp6
)) == REG
1367 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
1369 emit_insn (PATTERN (temp5
));
1371 init
= SET_SRC (temp6
);
1374 if (CONSTANT_P (init
)
1375 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
1376 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
1377 XEXP (temp3
, 0), XEXP (temp3
, 1),
1379 (code
== LTU
|| code
== LEU
1380 || code
== GTU
|| code
== GEU
), 1);
1382 /* If we can do the store-flag, do the addition or
1386 target
= expand_binop (GET_MODE (temp2
),
1387 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1388 ? add_optab
: sub_optab
),
1389 temp2
, target
, temp2
, 0, OPTAB_WIDEN
);
1393 /* Put the result back in temp2 in case it isn't already.
1394 Then replace the jump, possible a CC0-setting insn in
1395 front of the jump, and TEMP, with the sequence we have
1398 if (target
!= temp2
)
1399 emit_move_insn (temp2
, target
);
1404 emit_insns_before (seq
, temp4
);
1408 delete_insn (init_insn
);
1410 next
= NEXT_INSN (insn
);
1412 delete_insn (prev_nonnote_insn (insn
));
1422 /* Simplify if (...) x = 1; else {...} if (x) ...
1423 We recognize this case scanning backwards as well.
1425 TEMP is the assignment to x;
1426 TEMP1 is the label at the head of the second if. */
1427 /* ?? This should call get_condition to find the values being
1428 compared, instead of looking for a COMPARE insn when HAVE_cc0
1429 is not defined. This would allow it to work on the m88k. */
1430 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1431 is not defined and the condition is tested by a separate compare
1432 insn. This is because the code below assumes that the result
1433 of the compare dies in the following branch.
1435 Not only that, but there might be other insns between the
1436 compare and branch whose results are live. Those insns need
1439 A way to fix this is to move the insns at JUMP_LABEL (insn)
1440 to before INSN. If we are running before flow, they will
1441 be deleted if they aren't needed. But this doesn't work
1444 This is really a special-case of jump threading, anyway. The
1445 right thing to do is to replace this and jump threading with
1446 much simpler code in cse.
1448 This code has been turned off in the non-cc0 case in the
1452 else if (this_is_simplejump
1453 /* Safe to skip USE and CLOBBER insns here
1454 since they will not be deleted. */
1455 && (temp
= prev_active_insn (insn
))
1456 && no_labels_between_p (temp
, insn
)
1457 && GET_CODE (temp
) == INSN
1458 && GET_CODE (PATTERN (temp
)) == SET
1459 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1460 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1461 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1462 /* If we find that the next value tested is `x'
1463 (TEMP1 is the insn where this happens), win. */
1464 && GET_CODE (temp1
) == INSN
1465 && GET_CODE (PATTERN (temp1
)) == SET
1467 /* Does temp1 `tst' the value of x? */
1468 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1469 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1470 && (temp1
= next_nonnote_insn (temp1
))
1472 /* Does temp1 compare the value of x against zero? */
1473 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1474 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1475 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1476 == SET_DEST (PATTERN (temp
)))
1477 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1478 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1480 && condjump_p (temp1
))
1482 /* Get the if_then_else from the condjump. */
1483 rtx choice
= SET_SRC (PATTERN (temp1
));
1484 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1486 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1487 rtx val
= SET_SRC (PATTERN (temp
));
1489 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1493 if (cond
== const_true_rtx
)
1494 ultimate
= XEXP (choice
, 1);
1495 else if (cond
== const0_rtx
)
1496 ultimate
= XEXP (choice
, 2);
1500 if (ultimate
== pc_rtx
)
1501 ultimate
= get_label_after (temp1
);
1502 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1503 ultimate
= XEXP (ultimate
, 0);
1506 changed
|= redirect_jump (insn
, ultimate
);
1512 /* @@ This needs a bit of work before it will be right.
1514 Any type of comparison can be accepted for the first and
1515 second compare. When rewriting the first jump, we must
1516 compute the what conditions can reach label3, and use the
1517 appropriate code. We can not simply reverse/swap the code
1518 of the first jump. In some cases, the second jump must be
1522 < == converts to > ==
1523 < != converts to == >
1526 If the code is written to only accept an '==' test for the second
1527 compare, then all that needs to be done is to swap the condition
1528 of the first branch.
1530 It is questionable whether we want this optimization anyways,
1531 since if the user wrote code like this because he/she knew that
1532 the jump to label1 is taken most of the time, then rewriting
1533 this gives slower code. */
1534 /* @@ This should call get_condition to find the values being
1535 compared, instead of looking for a COMPARE insn when HAVE_cc0
1536 is not defined. This would allow it to work on the m88k. */
1537 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1538 is not defined and the condition is tested by a separate compare
1539 insn. This is because the code below assumes that the result
1540 of the compare dies in the following branch. */
1542 /* Simplify test a ~= b
1556 where ~= is an inequality, e.g. >, and ~~= is the swapped
1559 We recognize this case scanning backwards.
1561 TEMP is the conditional jump to `label2';
1562 TEMP1 is the test for `a == b';
1563 TEMP2 is the conditional jump to `label1';
1564 TEMP3 is the test for `a ~= b'. */
1565 else if (this_is_simplejump
1566 && (temp
= prev_active_insn (insn
))
1567 && no_labels_between_p (temp
, insn
)
1568 && condjump_p (temp
)
1569 && (temp1
= prev_active_insn (temp
))
1570 && no_labels_between_p (temp1
, temp
)
1571 && GET_CODE (temp1
) == INSN
1572 && GET_CODE (PATTERN (temp1
)) == SET
1574 && sets_cc0_p (PATTERN (temp1
)) == 1
1576 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1577 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1578 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1580 && (temp2
= prev_active_insn (temp1
))
1581 && no_labels_between_p (temp2
, temp1
)
1582 && condjump_p (temp2
)
1583 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1584 && (temp3
= prev_active_insn (temp2
))
1585 && no_labels_between_p (temp3
, temp2
)
1586 && GET_CODE (PATTERN (temp3
)) == SET
1587 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1588 SET_DEST (PATTERN (temp1
)))
1589 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1590 SET_SRC (PATTERN (temp3
)))
1591 && ! inequality_comparisons_p (PATTERN (temp
))
1592 && inequality_comparisons_p (PATTERN (temp2
)))
1594 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1596 ++LABEL_NUSES (fallthrough_label
);
1597 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1603 if (--LABEL_NUSES (fallthrough_label
) == 0)
1604 delete_insn (fallthrough_label
);
1607 /* Simplify if (...) {... x = 1;} if (x) ...
1609 We recognize this case backwards.
1611 TEMP is the test of `x';
1612 TEMP1 is the assignment to `x' at the end of the
1613 previous statement. */
1614 /* @@ This should call get_condition to find the values being
1615 compared, instead of looking for a COMPARE insn when HAVE_cc0
1616 is not defined. This would allow it to work on the m88k. */
1617 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1618 is not defined and the condition is tested by a separate compare
1619 insn. This is because the code below assumes that the result
1620 of the compare dies in the following branch. */
1622 /* ??? This has to be turned off. The problem is that the
1623 unconditional jump might indirectly end up branching to the
1624 label between TEMP1 and TEMP. We can't detect this, in general,
1625 since it may become a jump to there after further optimizations.
1626 If that jump is done, it will be deleted, so we will retry
1627 this optimization in the next pass, thus an infinite loop.
1629 The present code prevents this by putting the jump after the
1630 label, but this is not logically correct. */
1632 else if (this_is_condjump
1633 /* Safe to skip USE and CLOBBER insns here
1634 since they will not be deleted. */
1635 && (temp
= prev_active_insn (insn
))
1636 && no_labels_between_p (temp
, insn
)
1637 && GET_CODE (temp
) == INSN
1638 && GET_CODE (PATTERN (temp
)) == SET
1640 && sets_cc0_p (PATTERN (temp
)) == 1
1641 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1643 /* Temp must be a compare insn, we can not accept a register
1644 to register move here, since it may not be simply a
1646 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1647 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1648 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1649 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1650 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1652 /* May skip USE or CLOBBER insns here
1653 for checking for opportunity, since we
1654 take care of them later. */
1655 && (temp1
= prev_active_insn (temp
))
1656 && GET_CODE (temp1
) == INSN
1657 && GET_CODE (PATTERN (temp1
)) == SET
1659 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1661 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1662 == SET_DEST (PATTERN (temp1
)))
1664 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1665 /* If this isn't true, cse will do the job. */
1666 && ! no_labels_between_p (temp1
, temp
))
1668 /* Get the if_then_else from the condjump. */
1669 rtx choice
= SET_SRC (PATTERN (insn
));
1670 if (GET_CODE (choice
) == IF_THEN_ELSE
1671 && (GET_CODE (XEXP (choice
, 0)) == EQ
1672 || GET_CODE (XEXP (choice
, 0)) == NE
))
1674 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1679 /* Get the place that condjump will jump to
1680 if it is reached from here. */
1681 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1683 ultimate
= XEXP (choice
, 1);
1685 ultimate
= XEXP (choice
, 2);
1686 /* Get it as a CODE_LABEL. */
1687 if (ultimate
== pc_rtx
)
1688 ultimate
= get_label_after (insn
);
1690 /* Get the label out of the LABEL_REF. */
1691 ultimate
= XEXP (ultimate
, 0);
1693 /* Insert the jump immediately before TEMP, specifically
1694 after the label that is between TEMP1 and TEMP. */
1695 last_insn
= PREV_INSN (temp
);
1697 /* If we would be branching to the next insn, the jump
1698 would immediately be deleted and the re-inserted in
1699 a subsequent pass over the code. So don't do anything
1701 if (next_active_insn (last_insn
)
1702 != next_active_insn (ultimate
))
1704 emit_barrier_after (last_insn
);
1705 p
= emit_jump_insn_after (gen_jump (ultimate
),
1707 JUMP_LABEL (p
) = ultimate
;
1708 ++LABEL_NUSES (ultimate
);
1709 if (INSN_UID (ultimate
) < max_jump_chain
1710 && INSN_CODE (p
) < max_jump_chain
)
1712 jump_chain
[INSN_UID (p
)]
1713 = jump_chain
[INSN_UID (ultimate
)];
1714 jump_chain
[INSN_UID (ultimate
)] = p
;
1722 /* Detect a conditional jump going to the same place
1723 as an immediately following unconditional jump. */
1724 else if (this_is_condjump
1725 && (temp
= next_active_insn (insn
)) != 0
1726 && simplejump_p (temp
)
1727 && (next_active_insn (JUMP_LABEL (insn
))
1728 == next_active_insn (JUMP_LABEL (temp
))))
1734 /* Detect a conditional jump jumping over an unconditional jump. */
1736 else if ((this_is_condjump
|| this_is_condjump_in_parallel
)
1737 && ! this_is_simplejump
1738 && reallabelprev
!= 0
1739 && GET_CODE (reallabelprev
) == JUMP_INSN
1740 && prev_active_insn (reallabelprev
) == insn
1741 && no_labels_between_p (insn
, reallabelprev
)
1742 && simplejump_p (reallabelprev
))
1744 /* When we invert the unconditional jump, we will be
1745 decrementing the usage count of its old label.
1746 Make sure that we don't delete it now because that
1747 might cause the following code to be deleted. */
1748 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
1749 rtx prev_label
= JUMP_LABEL (insn
);
1752 ++LABEL_NUSES (prev_label
);
1754 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
1756 /* It is very likely that if there are USE insns before
1757 this jump, they hold REG_DEAD notes. These REG_DEAD
1758 notes are no longer valid due to this optimization,
1759 and will cause the life-analysis that following passes
1760 (notably delayed-branch scheduling) to think that
1761 these registers are dead when they are not.
1763 To prevent this trouble, we just remove the USE insns
1764 from the insn chain. */
1766 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
1767 && GET_CODE (PATTERN (prev_uses
)) == USE
)
1769 rtx useless
= prev_uses
;
1770 prev_uses
= prev_nonnote_insn (prev_uses
);
1771 delete_insn (useless
);
1774 delete_insn (reallabelprev
);
1779 /* We can now safely delete the label if it is unreferenced
1780 since the delete_insn above has deleted the BARRIER. */
1781 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
1782 delete_insn (prev_label
);
1787 /* Detect a jump to a jump. */
1789 nlabel
= follow_jumps (JUMP_LABEL (insn
));
1790 if (nlabel
!= JUMP_LABEL (insn
)
1791 && redirect_jump (insn
, nlabel
))
1797 /* Look for if (foo) bar; else break; */
1798 /* The insns look like this:
1799 insn = condjump label1;
1800 ...range1 (some insns)...
1803 ...range2 (some insns)...
1804 jump somewhere unconditionally
1807 rtx label1
= next_label (insn
);
1808 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1809 /* Don't do this optimization on the first round, so that
1810 jump-around-a-jump gets simplified before we ask here
1811 whether a jump is unconditional.
1813 Also don't do it when we are called after reload since
1814 it will confuse reorg. */
1816 && (reload_completed
? ! flag_delayed_branch
: 1)
1817 /* Make sure INSN is something we can invert. */
1818 && condjump_p (insn
)
1820 && JUMP_LABEL (insn
) == label1
1821 && LABEL_NUSES (label1
) == 1
1822 && GET_CODE (range1end
) == JUMP_INSN
1823 && simplejump_p (range1end
))
1825 rtx label2
= next_label (label1
);
1826 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
1827 if (range1end
!= range2end
1828 && JUMP_LABEL (range1end
) == label2
1829 && GET_CODE (range2end
) == JUMP_INSN
1830 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
1831 /* Invert the jump condition, so we
1832 still execute the same insns in each case. */
1833 && invert_jump (insn
, label1
))
1835 rtx range1beg
= next_active_insn (insn
);
1836 rtx range2beg
= next_active_insn (label1
);
1837 rtx range1after
, range2after
;
1838 rtx range1before
, range2before
;
1841 /* Include in each range any notes before it, to be
1842 sure that we get the line number note if any, even
1843 if there are other notes here. */
1844 while (PREV_INSN (range1beg
)
1845 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
)
1846 range1beg
= PREV_INSN (range1beg
);
1848 while (PREV_INSN (range2beg
)
1849 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
)
1850 range2beg
= PREV_INSN (range2beg
);
1852 /* Don't move NOTEs for blocks or loops; shift them
1853 outside the ranges, where they'll stay put. */
1854 range1beg
= squeeze_notes (range1beg
, range1end
);
1855 range2beg
= squeeze_notes (range2beg
, range2end
);
1857 /* Get current surrounds of the 2 ranges. */
1858 range1before
= PREV_INSN (range1beg
);
1859 range2before
= PREV_INSN (range2beg
);
1860 range1after
= NEXT_INSN (range1end
);
1861 range2after
= NEXT_INSN (range2end
);
1863 /* Splice range2 where range1 was. */
1864 NEXT_INSN (range1before
) = range2beg
;
1865 PREV_INSN (range2beg
) = range1before
;
1866 NEXT_INSN (range2end
) = range1after
;
1867 PREV_INSN (range1after
) = range2end
;
1868 /* Splice range1 where range2 was. */
1869 NEXT_INSN (range2before
) = range1beg
;
1870 PREV_INSN (range1beg
) = range2before
;
1871 NEXT_INSN (range1end
) = range2after
;
1872 PREV_INSN (range2after
) = range1end
;
1874 /* Check for a loop end note between the end of
1875 range2, and the next code label. If there is one,
1876 then what we have really seen is
1877 if (foo) break; end_of_loop;
1878 and moved the break sequence outside the loop.
1879 We must move the LOOP_END note to where the
1880 loop really ends now, or we will confuse loop
1882 for (;range2after
!= label2
; range2after
= rangenext
)
1884 rangenext
= NEXT_INSN (range2after
);
1885 if (GET_CODE (range2after
) == NOTE
1886 && (NOTE_LINE_NUMBER (range2after
)
1887 == NOTE_INSN_LOOP_END
))
1889 NEXT_INSN (PREV_INSN (range2after
))
1891 PREV_INSN (rangenext
)
1892 = PREV_INSN (range2after
);
1893 PREV_INSN (range2after
)
1894 = PREV_INSN (range1beg
);
1895 NEXT_INSN (range2after
) = range1beg
;
1896 NEXT_INSN (PREV_INSN (range1beg
))
1898 PREV_INSN (range1beg
) = range2after
;
1907 /* Now that the jump has been tensioned,
1908 try cross jumping: check for identical code
1909 before the jump and before its target label. */
1911 /* First, cross jumping of conditional jumps: */
1913 if (cross_jump
&& condjump_p (insn
))
1915 rtx newjpos
, newlpos
;
1916 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
1918 /* A conditional jump may be crossjumped
1919 only if the place it jumps to follows
1920 an opposing jump that comes back here. */
1922 if (x
!= 0 && ! jump_back_p (x
, insn
))
1923 /* We have no opposing jump;
1924 cannot cross jump this insn. */
1928 /* TARGET is nonzero if it is ok to cross jump
1929 to code before TARGET. If so, see if matches. */
1931 find_cross_jump (insn
, x
, 2,
1932 &newjpos
, &newlpos
);
1936 do_cross_jump (insn
, newjpos
, newlpos
);
1937 /* Make the old conditional jump
1938 into an unconditional one. */
1939 SET_SRC (PATTERN (insn
))
1940 = gen_rtx (LABEL_REF
, VOIDmode
, JUMP_LABEL (insn
));
1941 INSN_CODE (insn
) = -1;
1942 emit_barrier_after (insn
);
1943 /* Add to jump_chain unless this is a new label
1944 whose UID is too large. */
1945 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
1947 jump_chain
[INSN_UID (insn
)]
1948 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1949 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
1956 /* Cross jumping of unconditional jumps:
1957 a few differences. */
1959 if (cross_jump
&& simplejump_p (insn
))
1961 rtx newjpos
, newlpos
;
1966 /* TARGET is nonzero if it is ok to cross jump
1967 to code before TARGET. If so, see if matches. */
1968 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
1969 &newjpos
, &newlpos
);
1971 /* If cannot cross jump to code before the label,
1972 see if we can cross jump to another jump to
1974 /* Try each other jump to this label. */
1975 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
1976 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1977 target
!= 0 && newjpos
== 0;
1978 target
= jump_chain
[INSN_UID (target
)])
1980 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
1981 /* Ignore TARGET if it's deleted. */
1982 && ! INSN_DELETED_P (target
))
1983 find_cross_jump (insn
, target
, 2,
1984 &newjpos
, &newlpos
);
1988 do_cross_jump (insn
, newjpos
, newlpos
);
1994 /* This code was dead in the previous jump.c! */
1995 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
1997 /* Return insns all "jump to the same place"
1998 so we can cross-jump between any two of them. */
2000 rtx newjpos
, newlpos
, target
;
2004 /* If cannot cross jump to code before the label,
2005 see if we can cross jump to another jump to
2007 /* Try each other jump to this label. */
2008 for (target
= jump_chain
[0];
2009 target
!= 0 && newjpos
== 0;
2010 target
= jump_chain
[INSN_UID (target
)])
2012 && ! INSN_DELETED_P (target
)
2013 && GET_CODE (PATTERN (target
)) == RETURN
)
2014 find_cross_jump (insn
, target
, 2,
2015 &newjpos
, &newlpos
);
2019 do_cross_jump (insn
, newjpos
, newlpos
);
2030 /* Delete extraneous line number notes.
2031 Note that two consecutive notes for different lines are not really
2032 extraneous. There should be some indication where that line belonged,
2033 even if it became empty. */
2038 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2039 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
2041 /* Delete this note if it is identical to previous note. */
2043 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
2044 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
2057 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2058 in front of it. If the machine allows it at this point (we might be
2059 after reload for a leaf routine), it will improve optimization for it
2060 to be there. We do this both here and at the start of this pass since
2061 the RETURN might have been deleted by some of our optimizations. */
2062 insn
= get_last_insn ();
2063 while (insn
&& GET_CODE (insn
) == NOTE
)
2064 insn
= PREV_INSN (insn
);
2066 if (insn
&& GET_CODE (insn
) != BARRIER
)
2068 emit_jump_insn (gen_return ());
2074 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2075 If so, delete it, and record that this function can drop off the end. */
2081 /* One label can follow the end-note: the return label. */
2082 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
2083 /* Ordinary insns can follow it if returning a structure. */
2084 || GET_CODE (insn
) == INSN
2085 /* If machine uses explicit RETURN insns, no epilogue,
2086 then one of them follows the note. */
2087 || (GET_CODE (insn
) == JUMP_INSN
2088 && GET_CODE (PATTERN (insn
)) == RETURN
)
2089 /* Other kinds of notes can follow also. */
2090 || (GET_CODE (insn
) == NOTE
2091 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
2092 insn
= PREV_INSN (insn
);
2095 /* Report if control can fall through at the end of the function. */
2096 if (insn
&& GET_CODE (insn
) == NOTE
2097 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
)
2103 /* Show JUMP_CHAIN no longer valid. */
2107 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2108 jump. Assume that this unconditional jump is to the exit test code. If
2109 the code is sufficiently simple, make a copy of it before INSN,
2110 followed by a jump to the exit of the loop. Then delete the unconditional
2113 Note that it is possible we can get confused here if the jump immediately
2114 after the loop start branches outside the loop but within an outer loop.
2115 If we are near the exit of that loop, we will copy its exit test. This
2116 will not generate incorrect code, but could suppress some optimizations.
2117 However, such cases are degenerate loops anyway.
2119 Return 1 if we made the change, else 0.
2121 This is only safe immediately after a regscan pass because it uses the
2122 values of regno_first_uid and regno_last_uid. */
2125 duplicate_loop_exit_test (loop_start
)
2128 rtx insn
, set
, reg
, p
, link
;
2131 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
2133 int max_reg
= max_reg_num ();
2136 /* Scan the exit code. We do not perform this optimization if any insn:
2140 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2141 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2142 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2145 Also, don't do this if the exit code is more than 20 insns. */
2147 for (insn
= exitcode
;
2149 && ! (GET_CODE (insn
) == NOTE
2150 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
2151 insn
= NEXT_INSN (insn
))
2153 switch (GET_CODE (insn
))
2159 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2160 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2161 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
2166 if (++num_insns
> 20
2167 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
2168 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2174 /* Unless INSN is zero, we can do the optimization. */
2180 /* See if any insn sets a register only used in the loop exit code and
2181 not a user variable. If so, replace it with a new register. */
2182 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2183 if (GET_CODE (insn
) == INSN
2184 && (set
= single_set (insn
)) != 0
2185 && ((reg
= SET_DEST (set
), GET_CODE (reg
) == REG
)
2186 || (GET_CODE (reg
) == SUBREG
2187 && (reg
= SUBREG_REG (reg
), GET_CODE (reg
) == REG
)))
2188 && REGNO (reg
) >= FIRST_PSEUDO_REGISTER
2189 && regno_first_uid
[REGNO (reg
)] == INSN_UID (insn
))
2191 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
2192 if (regno_last_uid
[REGNO (reg
)] == INSN_UID (p
))
2197 /* We can do the replacement. Allocate reg_map if this is the
2198 first replacement we found. */
2201 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
2202 bzero ((char *) reg_map
, max_reg
* sizeof (rtx
));
2205 REG_LOOP_TEST_P (reg
) = 1;
2207 reg_map
[REGNO (reg
)] = gen_reg_rtx (GET_MODE (reg
));
2211 /* Now copy each insn. */
2212 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2213 switch (GET_CODE (insn
))
2216 copy
= emit_barrier_before (loop_start
);
2219 /* Only copy line-number notes. */
2220 if (NOTE_LINE_NUMBER (insn
) >= 0)
2222 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
2223 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
2228 copy
= emit_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2230 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2232 mark_jump_label (PATTERN (copy
), copy
, 0);
2234 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2236 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2237 if (REG_NOTE_KIND (link
) != REG_LABEL
)
2239 = copy_rtx (gen_rtx (EXPR_LIST
, REG_NOTE_KIND (link
),
2240 XEXP (link
, 0), REG_NOTES (copy
)));
2241 if (reg_map
&& REG_NOTES (copy
))
2242 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2246 copy
= emit_jump_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2248 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2249 mark_jump_label (PATTERN (copy
), copy
, 0);
2250 if (REG_NOTES (insn
))
2252 REG_NOTES (copy
) = copy_rtx (REG_NOTES (insn
));
2254 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2257 /* If this is a simple jump, add it to the jump chain. */
2259 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
2260 && simplejump_p (copy
))
2262 jump_chain
[INSN_UID (copy
)]
2263 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2264 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2272 /* Now clean up by emitting a jump to the end label and deleting the jump
2273 at the start of the loop. */
2274 if (! copy
|| GET_CODE (copy
) != BARRIER
)
2276 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
2278 mark_jump_label (PATTERN (copy
), copy
, 0);
2279 if (INSN_UID (copy
) < max_jump_chain
2280 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
2282 jump_chain
[INSN_UID (copy
)]
2283 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2284 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2286 emit_barrier_before (loop_start
);
2289 /* Mark the exit code as the virtual top of the converted loop. */
2290 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
2292 delete_insn (next_nonnote_insn (loop_start
));
2297 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2298 loop-end notes between START and END out before START. Assume that
2299 END is not such a note. START may be such a note. Returns the value
2300 of the new starting insn, which may be different if the original start
2304 squeeze_notes (start
, end
)
2310 for (insn
= start
; insn
!= end
; insn
= next
)
2312 next
= NEXT_INSN (insn
);
2313 if (GET_CODE (insn
) == NOTE
2314 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2315 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2316 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2317 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
2318 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
2319 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
2325 rtx prev
= PREV_INSN (insn
);
2326 PREV_INSN (insn
) = PREV_INSN (start
);
2327 NEXT_INSN (insn
) = start
;
2328 NEXT_INSN (PREV_INSN (insn
)) = insn
;
2329 PREV_INSN (NEXT_INSN (insn
)) = insn
;
2330 NEXT_INSN (prev
) = next
;
2331 PREV_INSN (next
) = prev
;
2339 /* Compare the instructions before insn E1 with those before E2
2340 to find an opportunity for cross jumping.
2341 (This means detecting identical sequences of insns followed by
2342 jumps to the same place, or followed by a label and a jump
2343 to that label, and replacing one with a jump to the other.)
2345 Assume E1 is a jump that jumps to label E2
2346 (that is not always true but it might as well be).
2347 Find the longest possible equivalent sequences
2348 and store the first insns of those sequences into *F1 and *F2.
2349 Store zero there if no equivalent preceding instructions are found.
2351 We give up if we find a label in stream 1.
2352 Actually we could transfer that label into stream 2. */
2355 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
2360 register rtx i1
= e1
, i2
= e2
;
2361 register rtx p1
, p2
;
2364 rtx last1
= 0, last2
= 0;
2365 rtx afterlast1
= 0, afterlast2
= 0;
2373 i1
= prev_nonnote_insn (i1
);
2375 i2
= PREV_INSN (i2
);
2376 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
2377 i2
= PREV_INSN (i2
);
2382 /* Don't allow the range of insns preceding E1 or E2
2383 to include the other (E2 or E1). */
2384 if (i2
== e1
|| i1
== e2
)
2387 /* If we will get to this code by jumping, those jumps will be
2388 tensioned to go directly to the new label (before I2),
2389 so this cross-jumping won't cost extra. So reduce the minimum. */
2390 if (GET_CODE (i1
) == CODE_LABEL
)
2396 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
2402 /* If this is a CALL_INSN, compare register usage information.
2403 If we don't check this on stack register machines, the two
2404 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2405 numbers of stack registers in the same basic block.
2406 If we don't check this on machines with delay slots, a delay slot may
2407 be filled that clobbers a parameter expected by the subroutine.
2409 ??? We take the simple route for now and assume that if they're
2410 equal, they were constructed identically. */
2412 if (GET_CODE (i1
) == CALL_INSN
2413 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1
),
2414 CALL_INSN_FUNCTION_USAGE (i2
)))
2418 /* If cross_jump_death_matters is not 0, the insn's mode
2419 indicates whether or not the insn contains any stack-like
2422 if (!lose
&& cross_jump_death_matters
&& GET_MODE (i1
) == QImode
)
2424 /* If register stack conversion has already been done, then
2425 death notes must also be compared before it is certain that
2426 the two instruction streams match. */
2429 HARD_REG_SET i1_regset
, i2_regset
;
2431 CLEAR_HARD_REG_SET (i1_regset
);
2432 CLEAR_HARD_REG_SET (i2_regset
);
2434 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
2435 if (REG_NOTE_KIND (note
) == REG_DEAD
2436 && STACK_REG_P (XEXP (note
, 0)))
2437 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
2439 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
2440 if (REG_NOTE_KIND (note
) == REG_DEAD
2441 && STACK_REG_P (XEXP (note
, 0)))
2442 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
2444 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
2453 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
2454 || ! rtx_renumbered_equal_p (p1
, p2
))
2456 /* The following code helps take care of G++ cleanups. */
2460 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
2461 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
2462 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
2463 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
2464 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
2465 /* If the equivalences are not to a constant, they may
2466 reference pseudos that no longer exist, so we can't
2468 && CONSTANT_P (XEXP (equiv1
, 0))
2469 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
2471 rtx s1
= single_set (i1
);
2472 rtx s2
= single_set (i2
);
2473 if (s1
!= 0 && s2
!= 0
2474 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
2476 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
2477 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
2478 if (! rtx_renumbered_equal_p (p1
, p2
))
2480 else if (apply_change_group ())
2485 /* Insns fail to match; cross jumping is limited to the following
2489 /* Don't allow the insn after a compare to be shared by
2490 cross-jumping unless the compare is also shared.
2491 Here, if either of these non-matching insns is a compare,
2492 exclude the following insn from possible cross-jumping. */
2493 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
2494 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
2497 /* If cross-jumping here will feed a jump-around-jump
2498 optimization, this jump won't cost extra, so reduce
2500 if (GET_CODE (i1
) == JUMP_INSN
2502 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
2508 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
2510 /* Ok, this insn is potentially includable in a cross-jump here. */
2511 afterlast1
= last1
, afterlast2
= last2
;
2512 last1
= i1
, last2
= i2
, --minimum
;
2516 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
2517 *f1
= last1
, *f2
= last2
;
2521 do_cross_jump (insn
, newjpos
, newlpos
)
2522 rtx insn
, newjpos
, newlpos
;
2524 /* Find an existing label at this point
2525 or make a new one if there is none. */
2526 register rtx label
= get_label_before (newlpos
);
2528 /* Make the same jump insn jump to the new point. */
2529 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2531 /* Remove from jump chain of returns. */
2532 delete_from_jump_chain (insn
);
2533 /* Change the insn. */
2534 PATTERN (insn
) = gen_jump (label
);
2535 INSN_CODE (insn
) = -1;
2536 JUMP_LABEL (insn
) = label
;
2537 LABEL_NUSES (label
)++;
2538 /* Add to new the jump chain. */
2539 if (INSN_UID (label
) < max_jump_chain
2540 && INSN_UID (insn
) < max_jump_chain
)
2542 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
2543 jump_chain
[INSN_UID (label
)] = insn
;
2547 redirect_jump (insn
, label
);
2549 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2550 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2551 the NEWJPOS stream. */
2553 while (newjpos
!= insn
)
2557 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
2558 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
2559 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
2560 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
2561 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
2562 remove_note (newlpos
, lnote
);
2564 delete_insn (newjpos
);
2565 newjpos
= next_real_insn (newjpos
);
2566 newlpos
= next_real_insn (newlpos
);
2570 /* Return the label before INSN, or put a new label there. */
2573 get_label_before (insn
)
2578 /* Find an existing label at this point
2579 or make a new one if there is none. */
2580 label
= prev_nonnote_insn (insn
);
2582 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2584 rtx prev
= PREV_INSN (insn
);
2586 label
= gen_label_rtx ();
2587 emit_label_after (label
, prev
);
2588 LABEL_NUSES (label
) = 0;
2593 /* Return the label after INSN, or put a new label there. */
2596 get_label_after (insn
)
2601 /* Find an existing label at this point
2602 or make a new one if there is none. */
2603 label
= next_nonnote_insn (insn
);
2605 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2607 label
= gen_label_rtx ();
2608 emit_label_after (label
, insn
);
2609 LABEL_NUSES (label
) = 0;
2614 /* Return 1 if INSN is a jump that jumps to right after TARGET
2615 only on the condition that TARGET itself would drop through.
2616 Assumes that TARGET is a conditional jump. */
2619 jump_back_p (insn
, target
)
2623 enum rtx_code codei
, codet
;
2625 if (simplejump_p (insn
) || ! condjump_p (insn
)
2626 || simplejump_p (target
)
2627 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
2630 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
2631 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
2633 codei
= GET_CODE (cinsn
);
2634 codet
= GET_CODE (ctarget
);
2636 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
2638 if (! can_reverse_comparison_p (cinsn
, insn
))
2640 codei
= reverse_condition (codei
);
2643 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
2645 if (! can_reverse_comparison_p (ctarget
, target
))
2647 codet
= reverse_condition (codet
);
2650 return (codei
== codet
2651 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
2652 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
2655 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2656 return non-zero if it is safe to reverse this comparison. It is if our
2657 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2658 this is known to be an integer comparison. */
2661 can_reverse_comparison_p (comparison
, insn
)
2667 /* If this is not actually a comparison, we can't reverse it. */
2668 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
2671 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
2672 /* If this is an NE comparison, it is safe to reverse it to an EQ
2673 comparison and vice versa, even for floating point. If no operands
2674 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2675 always false and NE is always true, so the reversal is also valid. */
2677 || GET_CODE (comparison
) == NE
2678 || GET_CODE (comparison
) == EQ
)
2681 arg0
= XEXP (comparison
, 0);
2683 /* Make sure ARG0 is one of the actual objects being compared. If we
2684 can't do this, we can't be sure the comparison can be reversed.
2686 Handle cc0 and a MODE_CC register. */
2687 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
2693 rtx prev
= prev_nonnote_insn (insn
);
2694 rtx set
= single_set (prev
);
2696 if (set
== 0 || SET_DEST (set
) != arg0
)
2699 arg0
= SET_SRC (set
);
2701 if (GET_CODE (arg0
) == COMPARE
)
2702 arg0
= XEXP (arg0
, 0);
2705 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2706 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2707 return (GET_CODE (arg0
) == CONST_INT
2708 || (GET_MODE (arg0
) != VOIDmode
2709 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
2710 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
2713 /* Given an rtx-code for a comparison, return the code
2714 for the negated comparison.
2715 WATCH OUT! reverse_condition is not safe to use on a jump
2716 that might be acting on the results of an IEEE floating point comparison,
2717 because of the special treatment of non-signaling nans in comparisons.
2718 Use can_reverse_comparison_p to be sure. */
2721 reverse_condition (code
)
2762 /* Similar, but return the code when two operands of a comparison are swapped.
2763 This IS safe for IEEE floating-point. */
2766 swap_condition (code
)
2805 /* Given a comparison CODE, return the corresponding unsigned comparison.
2806 If CODE is an equality comparison or already an unsigned comparison,
2807 CODE is returned. */
2810 unsigned_condition (code
)
2840 /* Similarly, return the signed version of a comparison. */
2843 signed_condition (code
)
2873 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2874 truth of CODE1 implies the truth of CODE2. */
2877 comparison_dominates_p (code1
, code2
)
2878 enum rtx_code code1
, code2
;
2886 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
2891 if (code2
== LE
|| code2
== NE
)
2896 if (code2
== GE
|| code2
== NE
)
2901 if (code2
== LEU
|| code2
== NE
)
2906 if (code2
== GEU
|| code2
== NE
)
2914 /* Return 1 if INSN is an unconditional jump and nothing else. */
2920 return (GET_CODE (insn
) == JUMP_INSN
2921 && GET_CODE (PATTERN (insn
)) == SET
2922 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
2923 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
2926 /* Return nonzero if INSN is a (possibly) conditional jump
2927 and nothing more. */
2933 register rtx x
= PATTERN (insn
);
2934 if (GET_CODE (x
) != SET
)
2936 if (GET_CODE (SET_DEST (x
)) != PC
)
2938 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2940 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2942 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2943 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2944 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2946 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2947 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2948 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2953 /* Return nonzero if INSN is a (possibly) conditional jump
2954 and nothing more. */
2957 condjump_in_parallel_p (insn
)
2960 register rtx x
= PATTERN (insn
);
2962 if (GET_CODE (x
) != PARALLEL
)
2965 x
= XVECEXP (x
, 0, 0);
2967 if (GET_CODE (x
) != SET
)
2969 if (GET_CODE (SET_DEST (x
)) != PC
)
2971 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2973 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2975 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2976 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2977 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2979 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2980 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2981 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2986 /* Return 1 if X is an RTX that does nothing but set the condition codes
2987 and CLOBBER or USE registers.
2988 Return -1 if X does explicitly set the condition codes,
2989 but also does other things. */
2996 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
2998 if (GET_CODE (x
) == PARALLEL
)
3002 int other_things
= 0;
3003 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
3005 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
3006 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
3008 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
3011 return ! sets_cc0
? 0 : other_things
? -1 : 1;
3019 /* Follow any unconditional jump at LABEL;
3020 return the ultimate label reached by any such chain of jumps.
3021 If LABEL is not followed by a jump, return LABEL.
3022 If the chain loops or we can't find end, return LABEL,
3023 since that tells caller to avoid changing the insn.
3025 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3026 a USE or CLOBBER. */
3029 follow_jumps (label
)
3034 register rtx value
= label
;
3039 && (insn
= next_active_insn (value
)) != 0
3040 && GET_CODE (insn
) == JUMP_INSN
3041 && (JUMP_LABEL (insn
) != 0 || GET_CODE (PATTERN (insn
)) == RETURN
)
3042 && (next
= NEXT_INSN (insn
))
3043 && GET_CODE (next
) == BARRIER
);
3046 /* Don't chain through the insn that jumps into a loop
3047 from outside the loop,
3048 since that would create multiple loop entry jumps
3049 and prevent loop optimization. */
3051 if (!reload_completed
)
3052 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
3053 if (GET_CODE (tem
) == NOTE
3054 && NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
)
3057 /* If we have found a cycle, make the insn jump to itself. */
3058 if (JUMP_LABEL (insn
) == label
)
3061 tem
= next_active_insn (JUMP_LABEL (insn
));
3062 if (tem
&& (GET_CODE (PATTERN (tem
)) == ADDR_VEC
3063 || GET_CODE (PATTERN (tem
)) == ADDR_DIFF_VEC
))
3066 value
= JUMP_LABEL (insn
);
3073 /* Assuming that field IDX of X is a vector of label_refs,
3074 replace each of them by the ultimate label reached by it.
3075 Return nonzero if a change is made.
3076 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3079 tension_vector_labels (x
, idx
)
3085 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
3087 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
3088 register rtx nlabel
= follow_jumps (olabel
);
3089 if (nlabel
&& nlabel
!= olabel
)
3091 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
3092 ++LABEL_NUSES (nlabel
);
3093 if (--LABEL_NUSES (olabel
) == 0)
3094 delete_insn (olabel
);
3101 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3102 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3103 in INSN, then store one of them in JUMP_LABEL (INSN).
3104 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3105 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3106 Also, when there are consecutive labels, canonicalize on the last of them.
3108 Note that two labels separated by a loop-beginning note
3109 must be kept distinct if we have not yet done loop-optimization,
3110 because the gap between them is where loop-optimize
3111 will want to move invariant code to. CROSS_JUMP tells us
3112 that loop-optimization is done with.
3114 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3115 two labels distinct if they are separated by only USE or CLOBBER insns. */
3118 mark_jump_label (x
, insn
, cross_jump
)
3123 register RTX_CODE code
= GET_CODE (x
);
3141 /* If this is a constant-pool reference, see if it is a label. */
3142 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3143 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3144 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
3149 rtx label
= XEXP (x
, 0);
3154 if (GET_CODE (label
) != CODE_LABEL
)
3157 /* Ignore references to labels of containing functions. */
3158 if (LABEL_REF_NONLOCAL_P (x
))
3161 /* If there are other labels following this one,
3162 replace it with the last of the consecutive labels. */
3163 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
3165 if (GET_CODE (next
) == CODE_LABEL
)
3167 else if (cross_jump
&& GET_CODE (next
) == INSN
3168 && (GET_CODE (PATTERN (next
)) == USE
3169 || GET_CODE (PATTERN (next
)) == CLOBBER
))
3171 else if (GET_CODE (next
) != NOTE
)
3173 else if (! cross_jump
3174 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
3175 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
))
3179 XEXP (x
, 0) = label
;
3180 ++LABEL_NUSES (label
);
3184 if (GET_CODE (insn
) == JUMP_INSN
)
3185 JUMP_LABEL (insn
) = label
;
3187 /* If we've changed OLABEL and we had a REG_LABEL note
3188 for it, update it as well. */
3189 else if (label
!= olabel
3190 && (note
= find_reg_note (insn
, REG_LABEL
, olabel
)) != 0)
3191 XEXP (note
, 0) = label
;
3193 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3195 else if (! find_reg_note (insn
, REG_LABEL
, label
))
3197 rtx next
= next_real_insn (label
);
3198 /* Don't record labels that refer to dispatch tables.
3199 This is not necessary, since the tablejump
3200 references the same label.
3201 And if we did record them, flow.c would make worse code. */
3203 || ! (GET_CODE (next
) == JUMP_INSN
3204 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
3205 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
)))
3206 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_LABEL
, label
,
3213 /* Do walk the labels in a vector, but not the first operand of an
3214 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3218 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
3220 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
3221 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
, cross_jump
);
3226 fmt
= GET_RTX_FORMAT (code
);
3227 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3230 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
3231 else if (fmt
[i
] == 'E')
3234 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3235 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
3240 /* If all INSN does is set the pc, delete it,
3241 and delete the insn that set the condition codes for it
3242 if that's what the previous thing was. */
3248 register rtx set
= single_set (insn
);
3250 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3251 delete_computation (insn
);
3254 /* Delete INSN and recursively delete insns that compute values used only
3255 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3256 If we are running before flow.c, we need do nothing since flow.c will
3257 delete dead code. We also can't know if the registers being used are
3258 dead or not at this point.
3260 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3261 nothing other than set a register that dies in this insn, we can delete
3264 On machines with CC0, if CC0 is used in this insn, we may be able to
3265 delete the insn that set it. */
3268 delete_computation (insn
)
3274 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
3276 rtx prev
= prev_nonnote_insn (insn
);
3277 /* We assume that at this stage
3278 CC's are always set explicitly
3279 and always immediately before the jump that
3280 will use them. So if the previous insn
3281 exists to set the CC's, delete it
3282 (unless it performs auto-increments, etc.). */
3283 if (prev
&& GET_CODE (prev
) == INSN
3284 && sets_cc0_p (PATTERN (prev
)))
3286 if (sets_cc0_p (PATTERN (prev
)) > 0
3287 && !FIND_REG_INC_NOTE (prev
, NULL_RTX
))
3288 delete_computation (prev
);
3290 /* Otherwise, show that cc0 won't be used. */
3291 REG_NOTES (prev
) = gen_rtx (EXPR_LIST
, REG_UNUSED
,
3292 cc0_rtx
, REG_NOTES (prev
));
3297 for (note
= REG_NOTES (insn
); note
; note
= next
)
3301 next
= XEXP (note
, 1);
3303 if (REG_NOTE_KIND (note
) != REG_DEAD
3304 /* Verify that the REG_NOTE is legitimate. */
3305 || GET_CODE (XEXP (note
, 0)) != REG
)
3308 for (our_prev
= prev_nonnote_insn (insn
);
3309 our_prev
&& GET_CODE (our_prev
) == INSN
;
3310 our_prev
= prev_nonnote_insn (our_prev
))
3312 /* If we reach a SEQUENCE, it is too complex to try to
3313 do anything with it, so give up. */
3314 if (GET_CODE (PATTERN (our_prev
)) == SEQUENCE
)
3317 if (GET_CODE (PATTERN (our_prev
)) == USE
3318 && GET_CODE (XEXP (PATTERN (our_prev
), 0)) == INSN
)
3319 /* reorg creates USEs that look like this. We leave them
3320 alone because reorg needs them for its own purposes. */
3323 if (reg_set_p (XEXP (note
, 0), PATTERN (our_prev
)))
3325 if (FIND_REG_INC_NOTE (our_prev
, NULL_RTX
))
3328 if (GET_CODE (PATTERN (our_prev
)) == PARALLEL
)
3330 /* If we find a SET of something else, we can't
3335 for (i
= 0; i
< XVECLEN (PATTERN (our_prev
), 0); i
++)
3337 rtx part
= XVECEXP (PATTERN (our_prev
), 0, i
);
3339 if (GET_CODE (part
) == SET
3340 && SET_DEST (part
) != XEXP (note
, 0))
3344 if (i
== XVECLEN (PATTERN (our_prev
), 0))
3345 delete_computation (our_prev
);
3347 else if (GET_CODE (PATTERN (our_prev
)) == SET
3348 && SET_DEST (PATTERN (our_prev
)) == XEXP (note
, 0))
3349 delete_computation (our_prev
);
3354 /* If OUR_PREV references the register that dies here, it is an
3355 additional use. Hence any prior SET isn't dead. However, this
3356 insn becomes the new place for the REG_DEAD note. */
3357 if (reg_overlap_mentioned_p (XEXP (note
, 0),
3358 PATTERN (our_prev
)))
3360 XEXP (note
, 1) = REG_NOTES (our_prev
);
3361 REG_NOTES (our_prev
) = note
;
3370 /* Delete insn INSN from the chain of insns and update label ref counts.
3371 May delete some following insns as a consequence; may even delete
3372 a label elsewhere and insns that follow it.
3374 Returns the first insn after INSN that was not deleted. */
3380 register rtx next
= NEXT_INSN (insn
);
3381 register rtx prev
= PREV_INSN (insn
);
3382 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
3383 register int dont_really_delete
= 0;
3385 while (next
&& INSN_DELETED_P (next
))
3386 next
= NEXT_INSN (next
);
3388 /* This insn is already deleted => return first following nondeleted. */
3389 if (INSN_DELETED_P (insn
))
3392 /* Don't delete user-declared labels. Convert them to special NOTEs
3394 if (was_code_label
&& LABEL_NAME (insn
) != 0
3395 && optimize
&& ! dont_really_delete
)
3397 PUT_CODE (insn
, NOTE
);
3398 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
3399 NOTE_SOURCE_FILE (insn
) = 0;
3400 dont_really_delete
= 1;
3403 /* Mark this insn as deleted. */
3404 INSN_DELETED_P (insn
) = 1;
3406 /* If this is an unconditional jump, delete it from the jump chain. */
3407 if (simplejump_p (insn
))
3408 delete_from_jump_chain (insn
);
3410 /* If instruction is followed by a barrier,
3411 delete the barrier too. */
3413 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
3415 INSN_DELETED_P (next
) = 1;
3416 next
= NEXT_INSN (next
);
3419 /* Patch out INSN (and the barrier if any) */
3421 if (optimize
&& ! dont_really_delete
)
3425 NEXT_INSN (prev
) = next
;
3426 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
3427 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
3428 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
3433 PREV_INSN (next
) = prev
;
3434 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
3435 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
3438 if (prev
&& NEXT_INSN (prev
) == 0)
3439 set_last_insn (prev
);
3442 /* If deleting a jump, decrement the count of the label,
3443 and delete the label if it is now unused. */
3445 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
3446 if (--LABEL_NUSES (JUMP_LABEL (insn
)) == 0)
3448 /* This can delete NEXT or PREV,
3449 either directly if NEXT is JUMP_LABEL (INSN),
3450 or indirectly through more levels of jumps. */
3451 delete_insn (JUMP_LABEL (insn
));
3452 /* I feel a little doubtful about this loop,
3453 but I see no clean and sure alternative way
3454 to find the first insn after INSN that is not now deleted.
3455 I hope this works. */
3456 while (next
&& INSN_DELETED_P (next
))
3457 next
= NEXT_INSN (next
);
3461 /* Likewise if we're deleting a dispatch table. */
3463 if (GET_CODE (insn
) == JUMP_INSN
3464 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
3465 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
3467 rtx pat
= PATTERN (insn
);
3468 int i
, diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
3469 int len
= XVECLEN (pat
, diff_vec_p
);
3471 for (i
= 0; i
< len
; i
++)
3472 if (--LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)) == 0)
3473 delete_insn (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0));
3474 while (next
&& INSN_DELETED_P (next
))
3475 next
= NEXT_INSN (next
);
3479 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
3480 prev
= PREV_INSN (prev
);
3482 /* If INSN was a label and a dispatch table follows it,
3483 delete the dispatch table. The tablejump must have gone already.
3484 It isn't useful to fall through into a table. */
3487 && NEXT_INSN (insn
) != 0
3488 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
3489 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
3490 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
3491 next
= delete_insn (NEXT_INSN (insn
));
3493 /* If INSN was a label, delete insns following it if now unreachable. */
3495 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
3497 register RTX_CODE code
;
3499 && (GET_RTX_CLASS (code
= GET_CODE (next
)) == 'i'
3501 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
3504 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
3505 next
= NEXT_INSN (next
);
3506 /* Keep going past other deleted labels to delete what follows. */
3507 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
3508 next
= NEXT_INSN (next
);
3510 /* Note: if this deletes a jump, it can cause more
3511 deletion of unreachable code, after a different label.
3512 As long as the value from this recursive call is correct,
3513 this invocation functions correctly. */
3514 next
= delete_insn (next
);
3521 /* Advance from INSN till reaching something not deleted
3522 then return that. May return INSN itself. */
3525 next_nondeleted_insn (insn
)
3528 while (INSN_DELETED_P (insn
))
3529 insn
= NEXT_INSN (insn
);
3533 /* Delete a range of insns from FROM to TO, inclusive.
3534 This is for the sake of peephole optimization, so assume
3535 that whatever these insns do will still be done by a new
3536 peephole insn that will replace them. */
3539 delete_for_peephole (from
, to
)
3540 register rtx from
, to
;
3542 register rtx insn
= from
;
3546 register rtx next
= NEXT_INSN (insn
);
3547 register rtx prev
= PREV_INSN (insn
);
3549 if (GET_CODE (insn
) != NOTE
)
3551 INSN_DELETED_P (insn
) = 1;
3553 /* Patch this insn out of the chain. */
3554 /* We don't do this all at once, because we
3555 must preserve all NOTEs. */
3557 NEXT_INSN (prev
) = next
;
3560 PREV_INSN (next
) = prev
;
3568 /* Note that if TO is an unconditional jump
3569 we *do not* delete the BARRIER that follows,
3570 since the peephole that replaces this sequence
3571 is also an unconditional jump in that case. */
3574 /* Invert the condition of the jump JUMP, and make it jump
3575 to label NLABEL instead of where it jumps now. */
3578 invert_jump (jump
, nlabel
)
3581 /* We have to either invert the condition and change the label or
3582 do neither. Either operation could fail. We first try to invert
3583 the jump. If that succeeds, we try changing the label. If that fails,
3584 we invert the jump back to what it was. */
3586 if (! invert_exp (PATTERN (jump
), jump
))
3589 if (redirect_jump (jump
, nlabel
))
3592 if (! invert_exp (PATTERN (jump
), jump
))
3593 /* This should just be putting it back the way it was. */
3599 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3601 Return 1 if we can do so, 0 if we cannot find a way to do so that
3602 matches a pattern. */
3605 invert_exp (x
, insn
)
3609 register RTX_CODE code
;
3613 code
= GET_CODE (x
);
3615 if (code
== IF_THEN_ELSE
)
3617 register rtx comp
= XEXP (x
, 0);
3620 /* We can do this in two ways: The preferable way, which can only
3621 be done if this is not an integer comparison, is to reverse
3622 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3623 of the IF_THEN_ELSE. If we can't do either, fail. */
3625 if (can_reverse_comparison_p (comp
, insn
)
3626 && validate_change (insn
, &XEXP (x
, 0),
3627 gen_rtx (reverse_condition (GET_CODE (comp
)),
3628 GET_MODE (comp
), XEXP (comp
, 0),
3629 XEXP (comp
, 1)), 0))
3633 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
3634 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
3635 return apply_change_group ();
3638 fmt
= GET_RTX_FORMAT (code
);
3639 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3642 if (! invert_exp (XEXP (x
, i
), insn
))
3647 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3648 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
3656 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3657 If the old jump target label is unused as a result,
3658 it and the code following it may be deleted.
3660 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3663 The return value will be 1 if the change was made, 0 if it wasn't (this
3664 can only occur for NLABEL == 0). */
3667 redirect_jump (jump
, nlabel
)
3670 register rtx olabel
= JUMP_LABEL (jump
);
3672 if (nlabel
== olabel
)
3675 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
3678 /* If this is an unconditional branch, delete it from the jump_chain of
3679 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3680 have UID's in range and JUMP_CHAIN is valid). */
3681 if (jump_chain
&& (simplejump_p (jump
)
3682 || GET_CODE (PATTERN (jump
)) == RETURN
))
3684 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
3686 delete_from_jump_chain (jump
);
3687 if (label_index
< max_jump_chain
3688 && INSN_UID (jump
) < max_jump_chain
)
3690 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
3691 jump_chain
[label_index
] = jump
;
3695 JUMP_LABEL (jump
) = nlabel
;
3697 ++LABEL_NUSES (nlabel
);
3699 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
3700 delete_insn (olabel
);
3705 /* Delete the instruction JUMP from any jump chain it might be on. */
3708 delete_from_jump_chain (jump
)
3712 rtx olabel
= JUMP_LABEL (jump
);
3714 /* Handle unconditional jumps. */
3715 if (jump_chain
&& olabel
!= 0
3716 && INSN_UID (olabel
) < max_jump_chain
3717 && simplejump_p (jump
))
3718 index
= INSN_UID (olabel
);
3719 /* Handle return insns. */
3720 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
3724 if (jump_chain
[index
] == jump
)
3725 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
3730 for (insn
= jump_chain
[index
];
3732 insn
= jump_chain
[INSN_UID (insn
)])
3733 if (jump_chain
[INSN_UID (insn
)] == jump
)
3735 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
3741 /* If NLABEL is nonzero, throughout the rtx at LOC,
3742 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3743 zero, alter (RETURN) to (LABEL_REF NLABEL).
3745 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3746 validity with validate_change. Convert (set (pc) (label_ref olabel))
3749 Return 0 if we found a change we would like to make but it is invalid.
3750 Otherwise, return 1. */
3753 redirect_exp (loc
, olabel
, nlabel
, insn
)
3758 register rtx x
= *loc
;
3759 register RTX_CODE code
= GET_CODE (x
);
3763 if (code
== LABEL_REF
)
3765 if (XEXP (x
, 0) == olabel
)
3768 XEXP (x
, 0) = nlabel
;
3770 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3774 else if (code
== RETURN
&& olabel
== 0)
3776 x
= gen_rtx (LABEL_REF
, VOIDmode
, nlabel
);
3777 if (loc
== &PATTERN (insn
))
3778 x
= gen_rtx (SET
, VOIDmode
, pc_rtx
, x
);
3779 return validate_change (insn
, loc
, x
, 0);
3782 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
3783 && GET_CODE (SET_SRC (x
)) == LABEL_REF
3784 && XEXP (SET_SRC (x
), 0) == olabel
)
3785 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3787 fmt
= GET_RTX_FORMAT (code
);
3788 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3791 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
3796 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3797 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
3805 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3807 If the old jump target label (before the dispatch table) becomes unused,
3808 it and the dispatch table may be deleted. In that case, find the insn
3809 before the jump references that label and delete it and logical successors
3813 redirect_tablejump (jump
, nlabel
)
3816 register rtx olabel
= JUMP_LABEL (jump
);
3818 /* Add this jump to the jump_chain of NLABEL. */
3819 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
3820 && INSN_UID (jump
) < max_jump_chain
)
3822 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
3823 jump_chain
[INSN_UID (nlabel
)] = jump
;
3826 PATTERN (jump
) = gen_jump (nlabel
);
3827 JUMP_LABEL (jump
) = nlabel
;
3828 ++LABEL_NUSES (nlabel
);
3829 INSN_CODE (jump
) = -1;
3831 if (--LABEL_NUSES (olabel
) == 0)
3833 delete_labelref_insn (jump
, olabel
, 0);
3834 delete_insn (olabel
);
3838 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3839 If we found one, delete it and then delete this insn if DELETE_THIS is
3840 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3843 delete_labelref_insn (insn
, label
, delete_this
)
3850 if (GET_CODE (insn
) != NOTE
3851 && reg_mentioned_p (label
, PATTERN (insn
)))
3862 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
3863 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
3877 /* Like rtx_equal_p except that it considers two REGs as equal
3878 if they renumber to the same value and considers two commutative
3879 operations to be the same if the order of the operands has been
3883 rtx_renumbered_equal_p (x
, y
)
3887 register RTX_CODE code
= GET_CODE (x
);
3893 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
3894 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
3895 && GET_CODE (SUBREG_REG (y
)) == REG
)))
3897 int reg_x
= -1, reg_y
= -1;
3898 int word_x
= 0, word_y
= 0;
3900 if (GET_MODE (x
) != GET_MODE (y
))
3903 /* If we haven't done any renumbering, don't
3904 make any assumptions. */
3905 if (reg_renumber
== 0)
3906 return rtx_equal_p (x
, y
);
3910 reg_x
= REGNO (SUBREG_REG (x
));
3911 word_x
= SUBREG_WORD (x
);
3913 if (reg_renumber
[reg_x
] >= 0)
3915 reg_x
= reg_renumber
[reg_x
] + word_x
;
3923 if (reg_renumber
[reg_x
] >= 0)
3924 reg_x
= reg_renumber
[reg_x
];
3927 if (GET_CODE (y
) == SUBREG
)
3929 reg_y
= REGNO (SUBREG_REG (y
));
3930 word_y
= SUBREG_WORD (y
);
3932 if (reg_renumber
[reg_y
] >= 0)
3934 reg_y
= reg_renumber
[reg_y
];
3942 if (reg_renumber
[reg_y
] >= 0)
3943 reg_y
= reg_renumber
[reg_y
];
3946 return reg_x
>= 0 && reg_x
== reg_y
&& word_x
== word_y
;
3949 /* Now we have disposed of all the cases
3950 in which different rtx codes can match. */
3951 if (code
!= GET_CODE (y
))
3963 return INTVAL (x
) == INTVAL (y
);
3966 /* We can't assume nonlocal labels have their following insns yet. */
3967 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
3968 return XEXP (x
, 0) == XEXP (y
, 0);
3970 /* Two label-refs are equivalent if they point at labels
3971 in the same position in the instruction stream. */
3972 return (next_real_insn (XEXP (x
, 0))
3973 == next_real_insn (XEXP (y
, 0)));
3976 return XSTR (x
, 0) == XSTR (y
, 0);
3979 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3981 if (GET_MODE (x
) != GET_MODE (y
))
3984 /* For commutative operations, the RTX match if the operand match in any
3985 order. Also handle the simple binary and unary cases without a loop. */
3986 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
3987 return ((rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
3988 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)))
3989 || (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 1))
3990 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 0))));
3991 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
3992 return (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
3993 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)));
3994 else if (GET_RTX_CLASS (code
) == '1')
3995 return rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0));
3997 /* Compare the elements. If any pair of corresponding elements
3998 fail to match, return 0 for the whole things. */
4000 fmt
= GET_RTX_FORMAT (code
);
4001 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4007 if (XWINT (x
, i
) != XWINT (y
, i
))
4012 if (XINT (x
, i
) != XINT (y
, i
))
4017 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4022 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
4027 if (XEXP (x
, i
) != XEXP (y
, i
))
4034 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4036 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4037 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
4048 /* If X is a hard register or equivalent to one or a subregister of one,
4049 return the hard register number. If X is a pseudo register that was not
4050 assigned a hard register, return the pseudo register number. Otherwise,
4051 return -1. Any rtx is valid for X. */
4057 if (GET_CODE (x
) == REG
)
4059 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
4060 return reg_renumber
[REGNO (x
)];
4063 if (GET_CODE (x
) == SUBREG
)
4065 int base
= true_regnum (SUBREG_REG (x
));
4066 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
4067 return SUBREG_WORD (x
) + base
;
4072 /* Optimize code of the form:
4074 for (x = a[i]; x; ...)
4076 for (x = a[i]; x; ...)
4080 Loop optimize will change the above code into
4084 { ...; if (! (x = ...)) break; }
4087 { ...; if (! (x = ...)) break; }
4090 In general, if the first test fails, the program can branch
4091 directly to `foo' and skip the second try which is doomed to fail.
4092 We run this after loop optimization and before flow analysis. */
4094 /* When comparing the insn patterns, we track the fact that different
4095 pseudo-register numbers may have been used in each computation.
4096 The following array stores an equivalence -- same_regs[I] == J means
4097 that pseudo register I was used in the first set of tests in a context
4098 where J was used in the second set. We also count the number of such
4099 pending equivalences. If nonzero, the expressions really aren't the
4102 static int *same_regs
;
4104 static int num_same_regs
;
4106 /* Track any registers modified between the target of the first jump and
4107 the second jump. They never compare equal. */
4109 static char *modified_regs
;
4111 /* Record if memory was modified. */
4113 static int modified_mem
;
4115 /* Called via note_stores on each insn between the target of the first
4116 branch and the second branch. It marks any changed registers. */
4119 mark_modified_reg (dest
, x
)
4125 if (GET_CODE (dest
) == SUBREG
)
4126 dest
= SUBREG_REG (dest
);
4128 if (GET_CODE (dest
) == MEM
)
4131 if (GET_CODE (dest
) != REG
)
4134 regno
= REGNO (dest
);
4135 if (regno
>= FIRST_PSEUDO_REGISTER
)
4136 modified_regs
[regno
] = 1;
4138 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
4139 modified_regs
[regno
+ i
] = 1;
4142 /* F is the first insn in the chain of insns. */
4145 thread_jumps (f
, max_reg
, flag_before_loop
)
4148 int flag_before_loop
;
4150 /* Basic algorithm is to find a conditional branch,
4151 the label it may branch to, and the branch after
4152 that label. If the two branches test the same condition,
4153 walk back from both branch paths until the insn patterns
4154 differ, or code labels are hit. If we make it back to
4155 the target of the first branch, then we know that the first branch
4156 will either always succeed or always fail depending on the relative
4157 senses of the two branches. So adjust the first branch accordingly
4160 rtx label
, b1
, b2
, t1
, t2
;
4161 enum rtx_code code1
, code2
;
4162 rtx b1op0
, b1op1
, b2op0
, b2op1
;
4167 /* Allocate register tables and quick-reset table. */
4168 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
4169 same_regs
= (int *) alloca (max_reg
* sizeof (int));
4170 all_reset
= (int *) alloca (max_reg
* sizeof (int));
4171 for (i
= 0; i
< max_reg
; i
++)
4178 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
4180 /* Get to a candidate branch insn. */
4181 if (GET_CODE (b1
) != JUMP_INSN
4182 || ! condjump_p (b1
) || simplejump_p (b1
)
4183 || JUMP_LABEL (b1
) == 0)
4186 bzero (modified_regs
, max_reg
* sizeof (char));
4189 bcopy ((char *) all_reset
, (char *) same_regs
,
4190 max_reg
* sizeof (int));
4193 label
= JUMP_LABEL (b1
);
4195 /* Look for a branch after the target. Record any registers and
4196 memory modified between the target and the branch. Stop when we
4197 get to a label since we can't know what was changed there. */
4198 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
4200 if (GET_CODE (b2
) == CODE_LABEL
)
4203 else if (GET_CODE (b2
) == JUMP_INSN
)
4205 /* If this is an unconditional jump and is the only use of
4206 its target label, we can follow it. */
4207 if (simplejump_p (b2
)
4208 && JUMP_LABEL (b2
) != 0
4209 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
4211 b2
= JUMP_LABEL (b2
);
4218 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
4221 if (GET_CODE (b2
) == CALL_INSN
)
4224 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
4225 if (call_used_regs
[i
] && ! fixed_regs
[i
]
4226 && i
!= STACK_POINTER_REGNUM
4227 && i
!= FRAME_POINTER_REGNUM
4228 && i
!= HARD_FRAME_POINTER_REGNUM
4229 && i
!= ARG_POINTER_REGNUM
)
4230 modified_regs
[i
] = 1;
4233 note_stores (PATTERN (b2
), mark_modified_reg
);
4236 /* Check the next candidate branch insn from the label
4239 || GET_CODE (b2
) != JUMP_INSN
4241 || ! condjump_p (b2
)
4242 || simplejump_p (b2
))
4245 /* Get the comparison codes and operands, reversing the
4246 codes if appropriate. If we don't have comparison codes,
4247 we can't do anything. */
4248 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
4249 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
4250 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
4251 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
4252 code1
= reverse_condition (code1
);
4254 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
4255 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
4256 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
4257 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
4258 code2
= reverse_condition (code2
);
4260 /* If they test the same things and knowing that B1 branches
4261 tells us whether or not B2 branches, check if we
4262 can thread the branch. */
4263 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
4264 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
4265 && (comparison_dominates_p (code1
, code2
)
4266 || comparison_dominates_p (code1
, reverse_condition (code2
))))
4268 t1
= prev_nonnote_insn (b1
);
4269 t2
= prev_nonnote_insn (b2
);
4271 while (t1
!= 0 && t2
!= 0)
4275 /* We have reached the target of the first branch.
4276 If there are no pending register equivalents,
4277 we know that this branch will either always
4278 succeed (if the senses of the two branches are
4279 the same) or always fail (if not). */
4282 if (num_same_regs
!= 0)
4285 if (comparison_dominates_p (code1
, code2
))
4286 new_label
= JUMP_LABEL (b2
);
4288 new_label
= get_label_after (b2
);
4290 if (JUMP_LABEL (b1
) != new_label
)
4292 rtx prev
= PREV_INSN (new_label
);
4294 if (flag_before_loop
4295 && NOTE_LINE_NUMBER (prev
) == NOTE_INSN_LOOP_BEG
)
4297 /* Don't thread to the loop label. If a loop
4298 label is reused, loop optimization will
4299 be disabled for that loop. */
4300 new_label
= gen_label_rtx ();
4301 emit_label_after (new_label
, PREV_INSN (prev
));
4303 changed
|= redirect_jump (b1
, new_label
);
4308 /* If either of these is not a normal insn (it might be
4309 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4310 have already been skipped above.) Similarly, fail
4311 if the insns are different. */
4312 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
4313 || recog_memoized (t1
) != recog_memoized (t2
)
4314 || ! rtx_equal_for_thread_p (PATTERN (t1
),
4318 t1
= prev_nonnote_insn (t1
);
4319 t2
= prev_nonnote_insn (t2
);
4326 /* This is like RTX_EQUAL_P except that it knows about our handling of
4327 possibly equivalent registers and knows to consider volatile and
4328 modified objects as not equal.
4330 YINSN is the insn containing Y. */
4333 rtx_equal_for_thread_p (x
, y
, yinsn
)
4339 register enum rtx_code code
;
4342 code
= GET_CODE (x
);
4343 /* Rtx's of different codes cannot be equal. */
4344 if (code
!= GET_CODE (y
))
4347 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4348 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4350 if (GET_MODE (x
) != GET_MODE (y
))
4353 /* For commutative operations, the RTX match if the operand match in any
4354 order. Also handle the simple binary and unary cases without a loop. */
4355 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4356 return ((rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4357 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
))
4358 || (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 1), yinsn
)
4359 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 0), yinsn
)));
4360 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4361 return (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4362 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
));
4363 else if (GET_RTX_CLASS (code
) == '1')
4364 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4366 /* Handle special-cases first. */
4370 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
4373 /* If neither is user variable or hard register, check for possible
4375 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
4376 || REGNO (x
) < FIRST_PSEUDO_REGISTER
4377 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
4380 if (same_regs
[REGNO (x
)] == -1)
4382 same_regs
[REGNO (x
)] = REGNO (y
);
4385 /* If this is the first time we are seeing a register on the `Y'
4386 side, see if it is the last use. If not, we can't thread the
4387 jump, so mark it as not equivalent. */
4388 if (regno_last_uid
[REGNO (y
)] != INSN_UID (yinsn
))
4394 return (same_regs
[REGNO (x
)] == REGNO (y
));
4399 /* If memory modified or either volatile, not equivalent.
4400 Else, check address. */
4401 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4404 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4407 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4413 /* Cancel a pending `same_regs' if setting equivalenced registers.
4414 Then process source. */
4415 if (GET_CODE (SET_DEST (x
)) == REG
4416 && GET_CODE (SET_DEST (y
)) == REG
)
4418 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
4420 same_regs
[REGNO (SET_DEST (x
))] = -1;
4423 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
4427 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
4430 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
4433 return XEXP (x
, 0) == XEXP (y
, 0);
4436 return XSTR (x
, 0) == XSTR (y
, 0);
4442 fmt
= GET_RTX_FORMAT (code
);
4443 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4448 if (XWINT (x
, i
) != XWINT (y
, i
))
4454 if (XINT (x
, i
) != XINT (y
, i
))
4460 /* Two vectors must have the same length. */
4461 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4464 /* And the corresponding elements must match. */
4465 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4466 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
4467 XVECEXP (y
, i
, j
), yinsn
) == 0)
4472 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
4478 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4483 /* These are just backpointers, so they don't matter. */
4489 /* It is believed that rtx's at this level will never
4490 contain anything but integers and other rtx's,
4491 except for within LABEL_REFs and SYMBOL_REFs. */