1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-97, 1998 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, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
58 #include "hard-reg-set.h"
60 #include "insn-config.h"
61 #include "insn-flags.h"
67 /* ??? Eventually must record somehow the labels used by jumps
68 from nested functions. */
69 /* Pre-record the next or previous real insn for each label?
70 No, this pass is very fast anyway. */
71 /* Condense consecutive labels?
72 This would make life analysis faster, maybe. */
73 /* Optimize jump y; x: ... y: jumpif... x?
74 Don't know if it is worth bothering with. */
75 /* Optimize two cases of conditional jump to conditional jump?
76 This can never delete any instruction or make anything dead,
77 or even change what is live at any point.
78 So perhaps let combiner do it. */
80 /* Vector indexed by uid.
81 For each CODE_LABEL, index by its uid to get first unconditional jump
82 that jumps to the label.
83 For each JUMP_INSN, index by its uid to get the next unconditional jump
84 that jumps to the same label.
85 Element 0 is the start of a chain of all return insns.
86 (It is safe to use element 0 because insn uid 0 is not used. */
88 static rtx
*jump_chain
;
90 /* List of labels referred to from initializers.
91 These can never be deleted. */
94 /* Maximum index in jump_chain. */
96 static int max_jump_chain
;
98 /* Set nonzero by jump_optimize if control can fall through
99 to the end of the function. */
102 /* Indicates whether death notes are significant in cross jump analysis.
103 Normally they are not significant, because of A and B jump to C,
104 and R dies in A, it must die in B. But this might not be true after
105 stack register conversion, and we must compare death notes in that
108 static int cross_jump_death_matters
= 0;
110 static int duplicate_loop_exit_test
PROTO((rtx
));
111 static void find_cross_jump
PROTO((rtx
, rtx
, int, rtx
*, rtx
*));
112 static void do_cross_jump
PROTO((rtx
, rtx
, rtx
));
113 static int jump_back_p
PROTO((rtx
, rtx
));
114 static int tension_vector_labels
PROTO((rtx
, int));
115 static void mark_jump_label
PROTO((rtx
, rtx
, int));
116 static void delete_computation
PROTO((rtx
));
117 static void delete_from_jump_chain
PROTO((rtx
));
118 static int delete_labelref_insn
PROTO((rtx
, rtx
, int));
119 static void redirect_tablejump
PROTO((rtx
, rtx
));
120 static rtx find_insert_position
PROTO((rtx
, rtx
));
122 /* Delete no-op jumps and optimize jumps to jumps
123 and jumps around jumps.
124 Delete unused labels and unreachable code.
126 If CROSS_JUMP is 1, detect matching code
127 before a jump and its destination and unify them.
128 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
130 If NOOP_MOVES is nonzero, delete no-op move insns.
132 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
133 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
135 If `optimize' is zero, don't change any code,
136 just determine whether control drops off the end of the function.
137 This case occurs when we have -W and not -O.
138 It works because `delete_insn' checks the value of `optimize'
139 and refrains from actually deleting when that is 0. */
142 jump_optimize (f
, cross_jump
, noop_moves
, after_regscan
)
148 register rtx insn
, next
, note
;
154 cross_jump_death_matters
= (cross_jump
== 2);
156 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
157 notes whose labels don't occur in the insn any more. */
159 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
161 if (GET_CODE (insn
) == CODE_LABEL
)
162 LABEL_NUSES (insn
) = (LABEL_PRESERVE_P (insn
) != 0);
163 else if (GET_CODE (insn
) == JUMP_INSN
)
164 JUMP_LABEL (insn
) = 0;
165 else if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == CALL_INSN
)
166 for (note
= REG_NOTES (insn
); note
; note
= next
)
168 next
= XEXP (note
, 1);
169 if (REG_NOTE_KIND (note
) == REG_LABEL
170 && ! reg_mentioned_p (XEXP (note
, 0), PATTERN (insn
)))
171 remove_note (insn
, note
);
174 if (INSN_UID (insn
) > max_uid
)
175 max_uid
= INSN_UID (insn
);
180 /* Delete insns following barriers, up to next label. */
182 for (insn
= f
; insn
;)
184 if (GET_CODE (insn
) == BARRIER
)
186 insn
= NEXT_INSN (insn
);
187 while (insn
!= 0 && GET_CODE (insn
) != CODE_LABEL
)
189 if (GET_CODE (insn
) == NOTE
190 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
191 insn
= NEXT_INSN (insn
);
193 insn
= delete_insn (insn
);
195 /* INSN is now the code_label. */
198 insn
= NEXT_INSN (insn
);
201 /* Leave some extra room for labels and duplicate exit test insns
203 max_jump_chain
= max_uid
* 14 / 10;
204 jump_chain
= (rtx
*) alloca (max_jump_chain
* sizeof (rtx
));
205 bzero ((char *) jump_chain
, max_jump_chain
* sizeof (rtx
));
207 /* Mark the label each jump jumps to.
208 Combine consecutive labels, and count uses of labels.
210 For each label, make a chain (using `jump_chain')
211 of all the *unconditional* jumps that jump to it;
212 also make a chain of all returns. */
214 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
215 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i'
216 && ! INSN_DELETED_P (insn
))
218 mark_jump_label (PATTERN (insn
), insn
, cross_jump
);
219 if (GET_CODE (insn
) == JUMP_INSN
)
221 if (JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
223 jump_chain
[INSN_UID (insn
)]
224 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
225 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
227 if (GET_CODE (PATTERN (insn
)) == RETURN
)
229 jump_chain
[INSN_UID (insn
)] = jump_chain
[0];
230 jump_chain
[0] = insn
;
235 /* Keep track of labels used from static data;
236 they cannot ever be deleted. */
238 for (insn
= forced_labels
; insn
; insn
= XEXP (insn
, 1))
239 LABEL_NUSES (XEXP (insn
, 0))++;
241 check_exception_handler_labels ();
243 /* Keep track of labels used for marking handlers for exception
244 regions; they cannot usually be deleted. */
246 for (insn
= exception_handler_labels
; insn
; insn
= XEXP (insn
, 1))
247 LABEL_NUSES (XEXP (insn
, 0))++;
249 exception_optimize ();
251 /* Delete all labels already not referenced.
252 Also find the last insn. */
255 for (insn
= f
; insn
; )
257 if (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NUSES (insn
) == 0)
258 insn
= delete_insn (insn
);
262 insn
= NEXT_INSN (insn
);
268 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
269 If so record that this function can drop off the end. */
275 /* One label can follow the end-note: the return label. */
276 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
277 /* Ordinary insns can follow it if returning a structure. */
278 || GET_CODE (insn
) == INSN
279 /* If machine uses explicit RETURN insns, no epilogue,
280 then one of them follows the note. */
281 || (GET_CODE (insn
) == JUMP_INSN
282 && GET_CODE (PATTERN (insn
)) == RETURN
)
283 /* A barrier can follow the return insn. */
284 || GET_CODE (insn
) == BARRIER
285 /* Other kinds of notes can follow also. */
286 || (GET_CODE (insn
) == NOTE
287 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
288 insn
= PREV_INSN (insn
);
291 /* Report if control can fall through at the end of the function. */
292 if (insn
&& GET_CODE (insn
) == NOTE
293 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
294 && ! INSN_DELETED_P (insn
))
297 /* Zero the "deleted" flag of all the "deleted" insns. */
298 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
299 INSN_DELETED_P (insn
) = 0;
306 /* If we fall through to the epilogue, see if we can insert a RETURN insn
307 in front of it. If the machine allows it at this point (we might be
308 after reload for a leaf routine), it will improve optimization for it
310 insn
= get_last_insn ();
311 while (insn
&& GET_CODE (insn
) == NOTE
)
312 insn
= PREV_INSN (insn
);
314 if (insn
&& GET_CODE (insn
) != BARRIER
)
316 emit_jump_insn (gen_return ());
323 for (insn
= f
; insn
; )
325 next
= NEXT_INSN (insn
);
327 if (GET_CODE (insn
) == INSN
)
329 register rtx body
= PATTERN (insn
);
331 /* Combine stack_adjusts with following push_insns. */
333 if (GET_CODE (body
) == SET
334 && SET_DEST (body
) == stack_pointer_rtx
335 && GET_CODE (SET_SRC (body
)) == PLUS
336 && XEXP (SET_SRC (body
), 0) == stack_pointer_rtx
337 && GET_CODE (XEXP (SET_SRC (body
), 1)) == CONST_INT
338 && INTVAL (XEXP (SET_SRC (body
), 1)) > 0)
341 rtx stack_adjust_insn
= insn
;
342 int stack_adjust_amount
= INTVAL (XEXP (SET_SRC (body
), 1));
343 int total_pushed
= 0;
346 /* Find all successive push insns. */
348 /* Don't convert more than three pushes;
349 that starts adding too many displaced addresses
350 and the whole thing starts becoming a losing
355 p
= next_nonnote_insn (p
);
356 if (p
== 0 || GET_CODE (p
) != INSN
)
359 if (GET_CODE (pbody
) != SET
)
361 dest
= SET_DEST (pbody
);
362 /* Allow a no-op move between the adjust and the push. */
363 if (GET_CODE (dest
) == REG
364 && GET_CODE (SET_SRC (pbody
)) == REG
365 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
367 if (! (GET_CODE (dest
) == MEM
368 && GET_CODE (XEXP (dest
, 0)) == POST_INC
369 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
372 if (total_pushed
+ GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)))
373 > stack_adjust_amount
)
375 total_pushed
+= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
378 /* Discard the amount pushed from the stack adjust;
379 maybe eliminate it entirely. */
380 if (total_pushed
>= stack_adjust_amount
)
382 delete_computation (stack_adjust_insn
);
383 total_pushed
= stack_adjust_amount
;
386 XEXP (SET_SRC (PATTERN (stack_adjust_insn
)), 1)
387 = GEN_INT (stack_adjust_amount
- total_pushed
);
389 /* Change the appropriate push insns to ordinary stores. */
391 while (total_pushed
> 0)
394 p
= next_nonnote_insn (p
);
395 if (GET_CODE (p
) != INSN
)
398 if (GET_CODE (pbody
) == SET
)
400 dest
= SET_DEST (pbody
);
401 if (! (GET_CODE (dest
) == MEM
402 && GET_CODE (XEXP (dest
, 0)) == POST_INC
403 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
405 total_pushed
-= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
406 /* If this push doesn't fully fit in the space
407 of the stack adjust that we deleted,
408 make another stack adjust here for what we
409 didn't use up. There should be peepholes
410 to recognize the resulting sequence of insns. */
411 if (total_pushed
< 0)
413 emit_insn_before (gen_add2_insn (stack_pointer_rtx
,
414 GEN_INT (- total_pushed
)),
419 = plus_constant (stack_pointer_rtx
, total_pushed
);
424 /* Detect and delete no-op move instructions
425 resulting from not allocating a parameter in a register. */
427 if (GET_CODE (body
) == SET
428 && (SET_DEST (body
) == SET_SRC (body
)
429 || (GET_CODE (SET_DEST (body
)) == MEM
430 && GET_CODE (SET_SRC (body
)) == MEM
431 && rtx_equal_p (SET_SRC (body
), SET_DEST (body
))))
432 && ! (GET_CODE (SET_DEST (body
)) == MEM
433 && MEM_VOLATILE_P (SET_DEST (body
)))
434 && ! (GET_CODE (SET_SRC (body
)) == MEM
435 && MEM_VOLATILE_P (SET_SRC (body
))))
436 delete_computation (insn
);
438 /* Detect and ignore no-op move instructions
439 resulting from smart or fortuitous register allocation. */
441 else if (GET_CODE (body
) == SET
)
443 int sreg
= true_regnum (SET_SRC (body
));
444 int dreg
= true_regnum (SET_DEST (body
));
446 if (sreg
== dreg
&& sreg
>= 0)
448 else if (sreg
>= 0 && dreg
>= 0)
451 rtx tem
= find_equiv_reg (NULL_RTX
, insn
, 0,
452 sreg
, NULL_PTR
, dreg
,
453 GET_MODE (SET_SRC (body
)));
456 && GET_MODE (tem
) == GET_MODE (SET_DEST (body
)))
458 /* DREG may have been the target of a REG_DEAD note in
459 the insn which makes INSN redundant. If so, reorg
460 would still think it is dead. So search for such a
461 note and delete it if we find it. */
462 if (! find_regno_note (insn
, REG_UNUSED
, dreg
))
463 for (trial
= prev_nonnote_insn (insn
);
464 trial
&& GET_CODE (trial
) != CODE_LABEL
;
465 trial
= prev_nonnote_insn (trial
))
466 if (find_regno_note (trial
, REG_DEAD
, dreg
))
468 remove_death (dreg
, trial
);
471 #ifdef PRESERVE_DEATH_INFO_REGNO_P
472 /* Deleting insn could lose a death-note for SREG
473 so don't do it if final needs accurate
475 if (PRESERVE_DEATH_INFO_REGNO_P (sreg
)
476 && (trial
= find_regno_note (insn
, REG_DEAD
, sreg
)))
478 /* Change this into a USE so that we won't emit
479 code for it, but still can keep the note. */
481 = gen_rtx_USE (VOIDmode
, XEXP (trial
, 0));
482 INSN_CODE (insn
) = -1;
483 /* Remove all reg notes but the REG_DEAD one. */
484 REG_NOTES (insn
) = trial
;
485 XEXP (trial
, 1) = NULL_RTX
;
492 else if (dreg
>= 0 && CONSTANT_P (SET_SRC (body
))
493 && find_equiv_reg (SET_SRC (body
), insn
, 0, dreg
,
495 GET_MODE (SET_DEST (body
))))
497 /* This handles the case where we have two consecutive
498 assignments of the same constant to pseudos that didn't
499 get a hard reg. Each SET from the constant will be
500 converted into a SET of the spill register and an
501 output reload will be made following it. This produces
502 two loads of the same constant into the same spill
507 /* Look back for a death note for the first reg.
508 If there is one, it is no longer accurate. */
509 while (in_insn
&& GET_CODE (in_insn
) != CODE_LABEL
)
511 if ((GET_CODE (in_insn
) == INSN
512 || GET_CODE (in_insn
) == JUMP_INSN
)
513 && find_regno_note (in_insn
, REG_DEAD
, dreg
))
515 remove_death (dreg
, in_insn
);
518 in_insn
= PREV_INSN (in_insn
);
521 /* Delete the second load of the value. */
525 else if (GET_CODE (body
) == PARALLEL
)
527 /* If each part is a set between two identical registers or
528 a USE or CLOBBER, delete the insn. */
532 for (i
= XVECLEN (body
, 0) - 1; i
>= 0; i
--)
534 tem
= XVECEXP (body
, 0, i
);
535 if (GET_CODE (tem
) == USE
|| GET_CODE (tem
) == CLOBBER
)
538 if (GET_CODE (tem
) != SET
539 || (sreg
= true_regnum (SET_SRC (tem
))) < 0
540 || (dreg
= true_regnum (SET_DEST (tem
))) < 0
548 /* Also delete insns to store bit fields if they are no-ops. */
549 /* Not worth the hair to detect this in the big-endian case. */
550 else if (! BYTES_BIG_ENDIAN
551 && GET_CODE (body
) == SET
552 && GET_CODE (SET_DEST (body
)) == ZERO_EXTRACT
553 && XEXP (SET_DEST (body
), 2) == const0_rtx
554 && XEXP (SET_DEST (body
), 0) == SET_SRC (body
)
555 && ! (GET_CODE (SET_SRC (body
)) == MEM
556 && MEM_VOLATILE_P (SET_SRC (body
))))
562 /* If we haven't yet gotten to reload and we have just run regscan,
563 delete any insn that sets a register that isn't used elsewhere.
564 This helps some of the optimizations below by having less insns
565 being jumped around. */
567 if (! reload_completed
&& after_regscan
)
568 for (insn
= f
; insn
; insn
= next
)
570 rtx set
= single_set (insn
);
572 next
= NEXT_INSN (insn
);
574 if (set
&& GET_CODE (SET_DEST (set
)) == REG
575 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
576 && REGNO_FIRST_UID (REGNO (SET_DEST (set
))) == INSN_UID (insn
)
577 /* We use regno_last_note_uid so as not to delete the setting
578 of a reg that's used in notes. A subsequent optimization
579 might arrange to use that reg for real. */
580 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set
))) == INSN_UID (insn
)
581 && ! side_effects_p (SET_SRC (set
))
582 && ! find_reg_note (insn
, REG_RETVAL
, 0))
586 /* Now iterate optimizing jumps until nothing changes over one pass. */
592 for (insn
= f
; insn
; insn
= next
)
595 rtx temp
, temp1
, temp2
, temp3
, temp4
, temp5
, temp6
;
597 int this_is_simplejump
, this_is_condjump
, reversep
;
598 int this_is_condjump_in_parallel
;
600 /* If NOT the first iteration, if this is the last jump pass
601 (just before final), do the special peephole optimizations.
602 Avoiding the first iteration gives ordinary jump opts
603 a chance to work before peephole opts. */
605 if (reload_completed
&& !first
&& !flag_no_peephole
)
606 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
610 /* That could have deleted some insns after INSN, so check now
611 what the following insn is. */
613 next
= NEXT_INSN (insn
);
615 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
616 jump. Try to optimize by duplicating the loop exit test if so.
617 This is only safe immediately after regscan, because it uses
618 the values of regno_first_uid and regno_last_uid. */
619 if (after_regscan
&& GET_CODE (insn
) == NOTE
620 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
621 && (temp1
= next_nonnote_insn (insn
)) != 0
622 && simplejump_p (temp1
))
624 temp
= PREV_INSN (insn
);
625 if (duplicate_loop_exit_test (insn
))
628 next
= NEXT_INSN (temp
);
633 if (GET_CODE (insn
) != JUMP_INSN
)
636 this_is_simplejump
= simplejump_p (insn
);
637 this_is_condjump
= condjump_p (insn
);
638 this_is_condjump_in_parallel
= condjump_in_parallel_p (insn
);
640 /* Tension the labels in dispatch tables. */
642 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
643 changed
|= tension_vector_labels (PATTERN (insn
), 0);
644 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
645 changed
|= tension_vector_labels (PATTERN (insn
), 1);
647 /* If a dispatch table always goes to the same place,
648 get rid of it and replace the insn that uses it. */
650 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
651 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
654 rtx pat
= PATTERN (insn
);
655 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
656 int len
= XVECLEN (pat
, diff_vec_p
);
657 rtx dispatch
= prev_real_insn (insn
);
659 for (i
= 0; i
< len
; i
++)
660 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
661 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
665 && GET_CODE (dispatch
) == JUMP_INSN
666 && JUMP_LABEL (dispatch
) != 0
667 /* Don't mess with a casesi insn. */
668 && !(GET_CODE (PATTERN (dispatch
)) == SET
669 && (GET_CODE (SET_SRC (PATTERN (dispatch
)))
671 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
673 redirect_tablejump (dispatch
,
674 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
679 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
681 /* If a jump references the end of the function, try to turn
682 it into a RETURN insn, possibly a conditional one. */
683 if (JUMP_LABEL (insn
)
684 && (next_active_insn (JUMP_LABEL (insn
)) == 0
685 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn
))))
687 changed
|= redirect_jump (insn
, NULL_RTX
);
689 /* Detect jump to following insn. */
690 if (reallabelprev
== insn
&& condjump_p (insn
))
692 next
= next_real_insn (JUMP_LABEL (insn
));
698 /* If we have an unconditional jump preceded by a USE, try to put
699 the USE before the target and jump there. This simplifies many
700 of the optimizations below since we don't have to worry about
701 dealing with these USE insns. We only do this if the label
702 being branch to already has the identical USE or if code
703 never falls through to that label. */
705 if (this_is_simplejump
706 && (temp
= prev_nonnote_insn (insn
)) != 0
707 && GET_CODE (temp
) == INSN
&& GET_CODE (PATTERN (temp
)) == USE
708 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
709 && (GET_CODE (temp1
) == BARRIER
710 || (GET_CODE (temp1
) == INSN
711 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
))))
712 /* Don't do this optimization if we have a loop containing only
713 the USE instruction, and the loop start label has a usage
714 count of 1. This is because we will redo this optimization
715 everytime through the outer loop, and jump opt will never
717 && ! ((temp2
= prev_nonnote_insn (temp
)) != 0
718 && temp2
== JUMP_LABEL (insn
)
719 && LABEL_NUSES (temp2
) == 1))
721 if (GET_CODE (temp1
) == BARRIER
)
723 emit_insn_after (PATTERN (temp
), temp1
);
724 temp1
= NEXT_INSN (temp1
);
728 redirect_jump (insn
, get_label_before (temp1
));
729 reallabelprev
= prev_real_insn (temp1
);
733 /* Simplify if (...) x = a; else x = b; by converting it
734 to x = b; if (...) x = a;
735 if B is sufficiently simple, the test doesn't involve X,
736 and nothing in the test modifies B or X.
738 If we have small register classes, we also can't do this if X
741 If the "x = b;" insn has any REG_NOTES, we don't do this because
742 of the possibility that we are running after CSE and there is a
743 REG_EQUAL note that is only valid if the branch has already been
744 taken. If we move the insn with the REG_EQUAL note, we may
745 fold the comparison to always be false in a later CSE pass.
746 (We could also delete the REG_NOTES when moving the insn, but it
747 seems simpler to not move it.) An exception is that we can move
748 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
749 value is the same as "b".
751 INSN is the branch over the `else' part.
755 TEMP to the jump insn preceding "x = a;"
757 TEMP2 to the insn that sets "x = b;"
758 TEMP3 to the insn that sets "x = a;"
759 TEMP4 to the set of "x = b"; */
761 if (this_is_simplejump
762 && (temp3
= prev_active_insn (insn
)) != 0
763 && GET_CODE (temp3
) == INSN
764 && (temp4
= single_set (temp3
)) != 0
765 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
766 && (! SMALL_REGISTER_CLASSES
767 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
768 && (temp2
= next_active_insn (insn
)) != 0
769 && GET_CODE (temp2
) == INSN
770 && (temp4
= single_set (temp2
)) != 0
771 && rtx_equal_p (SET_DEST (temp4
), temp1
)
772 && (GET_CODE (SET_SRC (temp4
)) == REG
773 || GET_CODE (SET_SRC (temp4
)) == SUBREG
774 || (GET_CODE (SET_SRC (temp4
)) == MEM
775 && RTX_UNCHANGING_P (SET_SRC (temp4
)))
776 || CONSTANT_P (SET_SRC (temp4
)))
777 && (REG_NOTES (temp2
) == 0
778 || ((REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUAL
779 || REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUIV
)
780 && XEXP (REG_NOTES (temp2
), 1) == 0
781 && rtx_equal_p (XEXP (REG_NOTES (temp2
), 0),
783 && (temp
= prev_active_insn (temp3
)) != 0
784 && condjump_p (temp
) && ! simplejump_p (temp
)
785 /* TEMP must skip over the "x = a;" insn */
786 && prev_real_insn (JUMP_LABEL (temp
)) == insn
787 && no_labels_between_p (insn
, JUMP_LABEL (temp
))
788 /* There must be no other entries to the "x = b;" insn. */
789 && no_labels_between_p (JUMP_LABEL (temp
), temp2
)
790 /* INSN must either branch to the insn after TEMP2 or the insn
791 after TEMP2 must branch to the same place as INSN. */
792 && (reallabelprev
== temp2
793 || ((temp5
= next_active_insn (temp2
)) != 0
794 && simplejump_p (temp5
)
795 && JUMP_LABEL (temp5
) == JUMP_LABEL (insn
))))
797 /* The test expression, X, may be a complicated test with
798 multiple branches. See if we can find all the uses of
799 the label that TEMP branches to without hitting a CALL_INSN
800 or a jump to somewhere else. */
801 rtx target
= JUMP_LABEL (temp
);
802 int nuses
= LABEL_NUSES (target
);
805 /* Set P to the first jump insn that goes around "x = a;". */
806 for (p
= temp
; nuses
&& p
; p
= prev_nonnote_insn (p
))
808 if (GET_CODE (p
) == JUMP_INSN
)
810 if (condjump_p (p
) && ! simplejump_p (p
)
811 && JUMP_LABEL (p
) == target
)
820 else if (GET_CODE (p
) == CALL_INSN
)
825 /* We cannot insert anything between a set of cc and its use
826 so if P uses cc0, we must back up to the previous insn. */
827 q
= prev_nonnote_insn (p
);
828 if (q
&& GET_RTX_CLASS (GET_CODE (q
)) == 'i'
829 && sets_cc0_p (PATTERN (q
)))
836 /* If we found all the uses and there was no data conflict, we
837 can move the assignment unless we can branch into the middle
840 && no_labels_between_p (p
, insn
)
841 && ! reg_referenced_between_p (temp1
, p
, NEXT_INSN (temp3
))
842 && ! reg_set_between_p (temp1
, p
, temp3
)
843 && (GET_CODE (SET_SRC (temp4
)) == CONST_INT
844 || ! reg_set_between_p (SET_SRC (temp4
), p
, temp2
)))
846 emit_insn_after_with_line_notes (PATTERN (temp2
), p
, temp2
);
849 /* Set NEXT to an insn that we know won't go away. */
850 next
= next_active_insn (insn
);
852 /* Delete the jump around the set. Note that we must do
853 this before we redirect the test jumps so that it won't
854 delete the code immediately following the assignment
855 we moved (which might be a jump). */
859 /* We either have two consecutive labels or a jump to
860 a jump, so adjust all the JUMP_INSNs to branch to where
862 for (p
= NEXT_INSN (p
); p
!= next
; p
= NEXT_INSN (p
))
863 if (GET_CODE (p
) == JUMP_INSN
)
864 redirect_jump (p
, target
);
871 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
872 to x = a; if (...) goto l; x = b;
873 if A is sufficiently simple, the test doesn't involve X,
874 and nothing in the test modifies A or X.
876 If we have small register classes, we also can't do this if X
879 If the "x = a;" insn has any REG_NOTES, we don't do this because
880 of the possibility that we are running after CSE and there is a
881 REG_EQUAL note that is only valid if the branch has already been
882 taken. If we move the insn with the REG_EQUAL note, we may
883 fold the comparison to always be false in a later CSE pass.
884 (We could also delete the REG_NOTES when moving the insn, but it
885 seems simpler to not move it.) An exception is that we can move
886 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
887 value is the same as "a".
893 TEMP to the jump insn preceding "x = a;"
895 TEMP2 to the insn that sets "x = b;"
896 TEMP3 to the insn that sets "x = a;"
897 TEMP4 to the set of "x = a"; */
899 if (this_is_simplejump
900 && (temp2
= next_active_insn (insn
)) != 0
901 && GET_CODE (temp2
) == INSN
902 && (temp4
= single_set (temp2
)) != 0
903 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
904 && (! SMALL_REGISTER_CLASSES
905 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
906 && (temp3
= prev_active_insn (insn
)) != 0
907 && GET_CODE (temp3
) == INSN
908 && (temp4
= single_set (temp3
)) != 0
909 && rtx_equal_p (SET_DEST (temp4
), temp1
)
910 && (GET_CODE (SET_SRC (temp4
)) == REG
911 || GET_CODE (SET_SRC (temp4
)) == SUBREG
912 || (GET_CODE (SET_SRC (temp4
)) == MEM
913 && RTX_UNCHANGING_P (SET_SRC (temp4
)))
914 || CONSTANT_P (SET_SRC (temp4
)))
915 && (REG_NOTES (temp3
) == 0
916 || ((REG_NOTE_KIND (REG_NOTES (temp3
)) == REG_EQUAL
917 || REG_NOTE_KIND (REG_NOTES (temp3
)) == REG_EQUIV
)
918 && XEXP (REG_NOTES (temp3
), 1) == 0
919 && rtx_equal_p (XEXP (REG_NOTES (temp3
), 0),
921 && (temp
= prev_active_insn (temp3
)) != 0
922 && condjump_p (temp
) && ! simplejump_p (temp
)
923 /* TEMP must skip over the "x = a;" insn */
924 && prev_real_insn (JUMP_LABEL (temp
)) == insn
925 && no_labels_between_p (temp
, insn
))
927 rtx prev_label
= JUMP_LABEL (temp
);
928 rtx insert_after
= prev_nonnote_insn (temp
);
931 /* We cannot insert anything between a set of cc and its use. */
932 if (insert_after
&& GET_RTX_CLASS (GET_CODE (insert_after
)) == 'i'
933 && sets_cc0_p (PATTERN (insert_after
)))
934 insert_after
= prev_nonnote_insn (insert_after
);
936 ++LABEL_NUSES (prev_label
);
939 && no_labels_between_p (insert_after
, temp
)
940 && ! reg_referenced_between_p (temp1
, insert_after
, temp3
)
941 && ! reg_referenced_between_p (temp1
, temp3
,
943 && ! reg_set_between_p (temp1
, insert_after
, temp
)
944 && (GET_CODE (SET_SRC (temp4
)) == CONST_INT
945 || ! reg_set_between_p (SET_SRC (temp4
),
947 && invert_jump (temp
, JUMP_LABEL (insn
)))
949 emit_insn_after_with_line_notes (PATTERN (temp3
),
950 insert_after
, temp3
);
953 /* Set NEXT to an insn that we know won't go away. */
957 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
958 delete_insn (prev_label
);
964 /* If we have if (...) x = exp; and branches are expensive,
965 EXP is a single insn, does not have any side effects, cannot
966 trap, and is not too costly, convert this to
967 t = exp; if (...) x = t;
969 Don't do this when we have CC0 because it is unlikely to help
970 and we'd need to worry about where to place the new insn and
971 the potential for conflicts. We also can't do this when we have
972 notes on the insn for the same reason as above.
976 TEMP to the "x = exp;" insn.
977 TEMP1 to the single set in the "x = exp; insn.
980 if (! reload_completed
981 && this_is_condjump
&& ! this_is_simplejump
983 && (temp
= next_nonnote_insn (insn
)) != 0
984 && GET_CODE (temp
) == INSN
985 && REG_NOTES (temp
) == 0
986 && (reallabelprev
== temp
987 || ((temp2
= next_active_insn (temp
)) != 0
988 && simplejump_p (temp2
)
989 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
990 && (temp1
= single_set (temp
)) != 0
991 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
992 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
993 && (! SMALL_REGISTER_CLASSES
994 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
995 && GET_CODE (SET_SRC (temp1
)) != REG
996 && GET_CODE (SET_SRC (temp1
)) != SUBREG
997 && GET_CODE (SET_SRC (temp1
)) != CONST_INT
998 && ! modified_in_p (PATTERN (insn
), temp
)
999 && ! side_effects_p (SET_SRC (temp1
))
1000 && ! may_trap_p (SET_SRC (temp1
))
1001 && rtx_cost (SET_SRC (temp1
), SET
) < 10)
1003 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
1005 if ((temp3
= find_insert_position (insn
, temp
))
1006 && validate_change (temp
, &SET_DEST (temp1
), new, 0))
1008 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
1009 emit_insn_after_with_line_notes (PATTERN (temp
),
1010 PREV_INSN (temp3
), temp
);
1012 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
1016 /* Similarly, if it takes two insns to compute EXP but they
1017 have the same destination. Here TEMP3 will be the second
1018 insn and TEMP4 the SET from that insn. */
1020 if (! reload_completed
1021 && this_is_condjump
&& ! this_is_simplejump
1023 && (temp
= next_nonnote_insn (insn
)) != 0
1024 && GET_CODE (temp
) == INSN
1025 && REG_NOTES (temp
) == 0
1026 && (temp3
= next_nonnote_insn (temp
)) != 0
1027 && GET_CODE (temp3
) == INSN
1028 && REG_NOTES (temp3
) == 0
1029 && (reallabelprev
== temp3
1030 || ((temp2
= next_active_insn (temp3
)) != 0
1031 && simplejump_p (temp2
)
1032 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
1033 && (temp1
= single_set (temp
)) != 0
1034 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
1035 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
1036 && (! SMALL_REGISTER_CLASSES
1037 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
1038 && ! modified_in_p (PATTERN (insn
), temp
)
1039 && ! side_effects_p (SET_SRC (temp1
))
1040 && ! may_trap_p (SET_SRC (temp1
))
1041 && rtx_cost (SET_SRC (temp1
), SET
) < 10
1042 && (temp4
= single_set (temp3
)) != 0
1043 && rtx_equal_p (SET_DEST (temp4
), temp2
)
1044 && ! modified_in_p (PATTERN (insn
), temp3
)
1045 && ! side_effects_p (SET_SRC (temp4
))
1046 && ! may_trap_p (SET_SRC (temp4
))
1047 && rtx_cost (SET_SRC (temp4
), SET
) < 10)
1049 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
1051 if ((temp5
= find_insert_position (insn
, temp
))
1052 && (temp6
= find_insert_position (insn
, temp3
))
1053 && validate_change (temp
, &SET_DEST (temp1
), new, 0))
1055 /* Use the earliest of temp5 and temp6. */
1058 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
1059 emit_insn_after_with_line_notes (PATTERN (temp
),
1060 PREV_INSN (temp6
), temp
);
1061 emit_insn_after_with_line_notes
1062 (replace_rtx (PATTERN (temp3
), temp2
, new),
1063 PREV_INSN (temp6
), temp3
);
1065 delete_insn (temp3
);
1066 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
1070 /* Finally, handle the case where two insns are used to
1071 compute EXP but a temporary register is used. Here we must
1072 ensure that the temporary register is not used anywhere else. */
1074 if (! reload_completed
1076 && this_is_condjump
&& ! this_is_simplejump
1078 && (temp
= next_nonnote_insn (insn
)) != 0
1079 && GET_CODE (temp
) == INSN
1080 && REG_NOTES (temp
) == 0
1081 && (temp3
= next_nonnote_insn (temp
)) != 0
1082 && GET_CODE (temp3
) == INSN
1083 && REG_NOTES (temp3
) == 0
1084 && (reallabelprev
== temp3
1085 || ((temp2
= next_active_insn (temp3
)) != 0
1086 && simplejump_p (temp2
)
1087 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
1088 && (temp1
= single_set (temp
)) != 0
1089 && (temp5
= SET_DEST (temp1
),
1090 (GET_CODE (temp5
) == REG
1091 || (GET_CODE (temp5
) == SUBREG
1092 && (temp5
= SUBREG_REG (temp5
),
1093 GET_CODE (temp5
) == REG
))))
1094 && REGNO (temp5
) >= FIRST_PSEUDO_REGISTER
1095 && REGNO_FIRST_UID (REGNO (temp5
)) == INSN_UID (temp
)
1096 && REGNO_LAST_UID (REGNO (temp5
)) == INSN_UID (temp3
)
1097 && ! modified_in_p (PATTERN (insn
), temp
)
1098 && ! side_effects_p (SET_SRC (temp1
))
1099 && ! may_trap_p (SET_SRC (temp1
))
1100 && rtx_cost (SET_SRC (temp1
), SET
) < 10
1101 && (temp4
= single_set (temp3
)) != 0
1102 && (temp2
= SET_DEST (temp4
), GET_CODE (temp2
) == REG
)
1103 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
1104 && (! SMALL_REGISTER_CLASSES
1105 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
1106 && rtx_equal_p (SET_DEST (temp4
), temp2
)
1107 && ! modified_in_p (PATTERN (insn
), temp3
)
1108 && ! side_effects_p (SET_SRC (temp4
))
1109 && ! may_trap_p (SET_SRC (temp4
))
1110 && rtx_cost (SET_SRC (temp4
), SET
) < 10)
1112 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
1114 if ((temp5
= find_insert_position (insn
, temp
))
1115 && (temp6
= find_insert_position (insn
, temp3
))
1116 && validate_change (temp3
, &SET_DEST (temp4
), new, 0))
1118 /* Use the earliest of temp5 and temp6. */
1121 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
1122 emit_insn_after_with_line_notes (PATTERN (temp
),
1123 PREV_INSN (temp6
), temp
);
1124 emit_insn_after_with_line_notes (PATTERN (temp3
),
1125 PREV_INSN (temp6
), temp3
);
1127 delete_insn (temp3
);
1128 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
1131 #endif /* HAVE_cc0 */
1133 /* Try to use a conditional move (if the target has them), or a
1134 store-flag insn. The general case is:
1136 1) x = a; if (...) x = b; and
1139 If the jump would be faster, the machine should not have defined
1140 the movcc or scc insns!. These cases are often made by the
1141 previous optimization.
1143 The second case is treated as x = x; if (...) x = b;.
1145 INSN here is the jump around the store. We set:
1147 TEMP to the "x = b;" insn.
1150 TEMP3 to A (X in the second case).
1151 TEMP4 to the condition being tested.
1152 TEMP5 to the earliest insn used to find the condition. */
1154 if (/* We can't do this after reload has completed. */
1156 && this_is_condjump
&& ! this_is_simplejump
1157 /* Set TEMP to the "x = b;" insn. */
1158 && (temp
= next_nonnote_insn (insn
)) != 0
1159 && GET_CODE (temp
) == INSN
1160 && GET_CODE (PATTERN (temp
)) == SET
1161 && GET_CODE (temp1
= SET_DEST (PATTERN (temp
))) == REG
1162 && (! SMALL_REGISTER_CLASSES
1163 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
1164 && (GET_CODE (temp2
= SET_SRC (PATTERN (temp
))) == REG
1165 || (GET_CODE (temp2
) == MEM
&& RTX_UNCHANGING_P (temp2
))
1166 || GET_CODE (temp2
) == SUBREG
1167 /* ??? How about floating point constants? */
1168 || CONSTANT_P (temp2
))
1169 /* Allow either form, but prefer the former if both apply.
1170 There is no point in using the old value of TEMP1 if
1171 it is a register, since cse will alias them. It can
1172 lose if the old value were a hard register since CSE
1173 won't replace hard registers. Avoid using TEMP3 if
1174 small register classes and it is a hard register. */
1175 && (((temp3
= reg_set_last (temp1
, insn
)) != 0
1176 && ! (SMALL_REGISTER_CLASSES
&& GET_CODE (temp3
) == REG
1177 && REGNO (temp3
) < FIRST_PSEUDO_REGISTER
))
1178 /* Make the latter case look like x = x; if (...) x = b; */
1179 || (temp3
= temp1
, 1))
1180 /* INSN must either branch to the insn after TEMP or the insn
1181 after TEMP must branch to the same place as INSN. */
1182 && (reallabelprev
== temp
1183 || ((temp4
= next_active_insn (temp
)) != 0
1184 && simplejump_p (temp4
)
1185 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
1186 && (temp4
= get_condition (insn
, &temp5
)) != 0
1187 /* We must be comparing objects whose modes imply the size.
1188 We could handle BLKmode if (1) emit_store_flag could
1189 and (2) we could find the size reliably. */
1190 && GET_MODE (XEXP (temp4
, 0)) != BLKmode
1191 /* Even if branches are cheap, the store_flag optimization
1192 can win when the operation to be performed can be
1193 expressed directly. */
1195 /* If the previous insn sets CC0 and something else, we can't
1196 do this since we are going to delete that insn. */
1198 && ! ((temp6
= prev_nonnote_insn (insn
)) != 0
1199 && GET_CODE (temp6
) == INSN
1200 && (sets_cc0_p (PATTERN (temp6
)) == -1
1201 || (sets_cc0_p (PATTERN (temp6
)) == 1
1202 && FIND_REG_INC_NOTE (temp6
, NULL_RTX
))))
1206 #ifdef HAVE_conditional_move
1207 /* First try a conditional move. */
1209 enum rtx_code code
= GET_CODE (temp4
);
1211 rtx cond0
, cond1
, aval
, bval
;
1214 /* Copy the compared variables into cond0 and cond1, so that
1215 any side effects performed in or after the old comparison,
1216 will not affect our compare which will come later. */
1217 /* ??? Is it possible to just use the comparison in the jump
1218 insn? After all, we're going to delete it. We'd have
1219 to modify emit_conditional_move to take a comparison rtx
1220 instead or write a new function. */
1221 cond0
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 0)));
1222 /* We want the target to be able to simplify comparisons with
1223 zero (and maybe other constants as well), so don't create
1224 pseudos for them. There's no need to either. */
1225 if (GET_CODE (XEXP (temp4
, 1)) == CONST_INT
1226 || GET_CODE (XEXP (temp4
, 1)) == CONST_DOUBLE
)
1227 cond1
= XEXP (temp4
, 1);
1229 cond1
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 1)));
1235 target
= emit_conditional_move (var
, code
,
1236 cond0
, cond1
, VOIDmode
,
1237 aval
, bval
, GET_MODE (var
),
1238 (code
== LTU
|| code
== GEU
1239 || code
== LEU
|| code
== GTU
));
1245 /* Save the conditional move sequence but don't emit it
1246 yet. On some machines, like the alpha, it is possible
1247 that temp5 == insn, so next generate the sequence that
1248 saves the compared values and then emit both
1249 sequences ensuring seq1 occurs before seq2. */
1250 seq2
= get_insns ();
1253 /* Now that we can't fail, generate the copy insns that
1254 preserve the compared values. */
1256 emit_move_insn (cond0
, XEXP (temp4
, 0));
1257 if (cond1
!= XEXP (temp4
, 1))
1258 emit_move_insn (cond1
, XEXP (temp4
, 1));
1259 seq1
= get_insns ();
1262 emit_insns_before (seq1
, temp5
);
1263 /* Insert conditional move after insn, to be sure that
1264 the jump and a possible compare won't be separated */
1265 emit_insns_after (seq2
, insn
);
1267 /* ??? We can also delete the insn that sets X to A.
1268 Flow will do it too though. */
1270 next
= NEXT_INSN (insn
);
1280 /* That didn't work, try a store-flag insn.
1282 We further divide the cases into:
1284 1) x = a; if (...) x = b; and either A or B is zero,
1285 2) if (...) x = 0; and jumps are expensive,
1286 3) x = a; if (...) x = b; and A and B are constants where all
1287 the set bits in A are also set in B and jumps are expensive,
1288 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1290 5) if (...) x = b; if jumps are even more expensive. */
1292 if (GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
1293 && ((GET_CODE (temp3
) == CONST_INT
)
1294 /* Make the latter case look like
1295 x = x; if (...) x = 0; */
1298 && temp2
== const0_rtx
)
1299 || BRANCH_COST
>= 3)))
1300 /* If B is zero, OK; if A is zero, can only do (1) if we
1301 can reverse the condition. See if (3) applies possibly
1302 by reversing the condition. Prefer reversing to (4) when
1303 branches are very expensive. */
1304 && (((BRANCH_COST
>= 2
1305 || STORE_FLAG_VALUE
== -1
1306 || (STORE_FLAG_VALUE
== 1
1307 /* Check that the mask is a power of two,
1308 so that it can probably be generated
1310 && exact_log2 (INTVAL (temp3
)) >= 0))
1311 && (reversep
= 0, temp2
== const0_rtx
))
1312 || ((BRANCH_COST
>= 2
1313 || STORE_FLAG_VALUE
== -1
1314 || (STORE_FLAG_VALUE
== 1
1315 && exact_log2 (INTVAL (temp2
)) >= 0))
1316 && temp3
== const0_rtx
1317 && (reversep
= can_reverse_comparison_p (temp4
, insn
)))
1318 || (BRANCH_COST
>= 2
1319 && GET_CODE (temp2
) == CONST_INT
1320 && GET_CODE (temp3
) == CONST_INT
1321 && ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp2
)
1322 || ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp3
)
1323 && (reversep
= can_reverse_comparison_p (temp4
,
1325 || BRANCH_COST
>= 3)
1328 enum rtx_code code
= GET_CODE (temp4
);
1329 rtx uval
, cval
, var
= temp1
;
1333 /* If necessary, reverse the condition. */
1335 code
= reverse_condition (code
), uval
= temp2
, cval
= temp3
;
1337 uval
= temp3
, cval
= temp2
;
1339 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1340 is the constant 1, it is best to just compute the result
1341 directly. If UVAL is constant and STORE_FLAG_VALUE
1342 includes all of its bits, it is best to compute the flag
1343 value unnormalized and `and' it with UVAL. Otherwise,
1344 normalize to -1 and `and' with UVAL. */
1345 normalizep
= (cval
!= const0_rtx
? -1
1346 : (uval
== const1_rtx
? 1
1347 : (GET_CODE (uval
) == CONST_INT
1348 && (INTVAL (uval
) & ~STORE_FLAG_VALUE
) == 0)
1351 /* We will be putting the store-flag insn immediately in
1352 front of the comparison that was originally being done,
1353 so we know all the variables in TEMP4 will be valid.
1354 However, this might be in front of the assignment of
1355 A to VAR. If it is, it would clobber the store-flag
1356 we will be emitting.
1358 Therefore, emit into a temporary which will be copied to
1359 VAR immediately after TEMP. */
1362 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
1363 XEXP (temp4
, 0), XEXP (temp4
, 1),
1365 (code
== LTU
|| code
== LEU
1366 || code
== GEU
|| code
== GTU
),
1376 /* Put the store-flag insns in front of the first insn
1377 used to compute the condition to ensure that we
1378 use the same values of them as the current
1379 comparison. However, the remainder of the insns we
1380 generate will be placed directly in front of the
1381 jump insn, in case any of the pseudos we use
1382 are modified earlier. */
1384 emit_insns_before (seq
, temp5
);
1388 /* Both CVAL and UVAL are non-zero. */
1389 if (cval
!= const0_rtx
&& uval
!= const0_rtx
)
1393 tem1
= expand_and (uval
, target
, NULL_RTX
);
1394 if (GET_CODE (cval
) == CONST_INT
1395 && GET_CODE (uval
) == CONST_INT
1396 && (INTVAL (cval
) & INTVAL (uval
)) == INTVAL (cval
))
1400 tem2
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1401 target
, NULL_RTX
, 0);
1402 tem2
= expand_and (cval
, tem2
,
1403 (GET_CODE (tem2
) == REG
1407 /* If we usually make new pseudos, do so here. This
1408 turns out to help machines that have conditional
1410 /* ??? Conditional moves have already been handled.
1411 This may be obsolete. */
1413 if (flag_expensive_optimizations
)
1416 target
= expand_binop (GET_MODE (var
), ior_optab
,
1420 else if (normalizep
!= 1)
1422 /* We know that either CVAL or UVAL is zero. If
1423 UVAL is zero, negate TARGET and `and' with CVAL.
1424 Otherwise, `and' with UVAL. */
1425 if (uval
== const0_rtx
)
1427 target
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1428 target
, NULL_RTX
, 0);
1432 target
= expand_and (uval
, target
,
1433 (GET_CODE (target
) == REG
1434 && ! preserve_subexpressions_p ()
1435 ? target
: NULL_RTX
));
1438 emit_move_insn (var
, target
);
1442 /* If INSN uses CC0, we must not separate it from the
1443 insn that sets cc0. */
1444 if (reg_mentioned_p (cc0_rtx
, PATTERN (before
)))
1445 before
= prev_nonnote_insn (before
);
1447 emit_insns_before (seq
, before
);
1450 next
= NEXT_INSN (insn
);
1460 /* If branches are expensive, convert
1461 if (foo) bar++; to bar += (foo != 0);
1462 and similarly for "bar--;"
1464 INSN is the conditional branch around the arithmetic. We set:
1466 TEMP is the arithmetic insn.
1467 TEMP1 is the SET doing the arithmetic.
1468 TEMP2 is the operand being incremented or decremented.
1469 TEMP3 to the condition being tested.
1470 TEMP4 to the earliest insn used to find the condition. */
1472 if ((BRANCH_COST
>= 2
1480 && ! reload_completed
1481 && this_is_condjump
&& ! this_is_simplejump
1482 && (temp
= next_nonnote_insn (insn
)) != 0
1483 && (temp1
= single_set (temp
)) != 0
1484 && (temp2
= SET_DEST (temp1
),
1485 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
1486 && GET_CODE (SET_SRC (temp1
)) == PLUS
1487 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1488 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
1489 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
1490 && ! side_effects_p (temp2
)
1491 && ! may_trap_p (temp2
)
1492 /* INSN must either branch to the insn after TEMP or the insn
1493 after TEMP must branch to the same place as INSN. */
1494 && (reallabelprev
== temp
1495 || ((temp3
= next_active_insn (temp
)) != 0
1496 && simplejump_p (temp3
)
1497 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
1498 && (temp3
= get_condition (insn
, &temp4
)) != 0
1499 /* We must be comparing objects whose modes imply the size.
1500 We could handle BLKmode if (1) emit_store_flag could
1501 and (2) we could find the size reliably. */
1502 && GET_MODE (XEXP (temp3
, 0)) != BLKmode
1503 && can_reverse_comparison_p (temp3
, insn
))
1505 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
1506 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
1510 /* It must be the case that TEMP2 is not modified in the range
1511 [TEMP4, INSN). The one exception we make is if the insn
1512 before INSN sets TEMP2 to something which is also unchanged
1513 in that range. In that case, we can move the initialization
1514 into our sequence. */
1516 if ((temp5
= prev_active_insn (insn
)) != 0
1517 && no_labels_between_p (temp5
, insn
)
1518 && GET_CODE (temp5
) == INSN
1519 && (temp6
= single_set (temp5
)) != 0
1520 && rtx_equal_p (temp2
, SET_DEST (temp6
))
1521 && (CONSTANT_P (SET_SRC (temp6
))
1522 || GET_CODE (SET_SRC (temp6
)) == REG
1523 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
1525 emit_insn (PATTERN (temp5
));
1527 init
= SET_SRC (temp6
);
1530 if (CONSTANT_P (init
)
1531 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
1532 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
1533 XEXP (temp3
, 0), XEXP (temp3
, 1),
1535 (code
== LTU
|| code
== LEU
1536 || code
== GTU
|| code
== GEU
), 1);
1538 /* If we can do the store-flag, do the addition or
1542 target
= expand_binop (GET_MODE (temp2
),
1543 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1544 ? add_optab
: sub_optab
),
1545 temp2
, target
, temp2
, 0, OPTAB_WIDEN
);
1549 /* Put the result back in temp2 in case it isn't already.
1550 Then replace the jump, possible a CC0-setting insn in
1551 front of the jump, and TEMP, with the sequence we have
1554 if (target
!= temp2
)
1555 emit_move_insn (temp2
, target
);
1560 emit_insns_before (seq
, temp4
);
1564 delete_insn (init_insn
);
1566 next
= NEXT_INSN (insn
);
1568 delete_insn (prev_nonnote_insn (insn
));
1578 /* Simplify if (...) x = 1; else {...} if (x) ...
1579 We recognize this case scanning backwards as well.
1581 TEMP is the assignment to x;
1582 TEMP1 is the label at the head of the second if. */
1583 /* ?? This should call get_condition to find the values being
1584 compared, instead of looking for a COMPARE insn when HAVE_cc0
1585 is not defined. This would allow it to work on the m88k. */
1586 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1587 is not defined and the condition is tested by a separate compare
1588 insn. This is because the code below assumes that the result
1589 of the compare dies in the following branch.
1591 Not only that, but there might be other insns between the
1592 compare and branch whose results are live. Those insns need
1595 A way to fix this is to move the insns at JUMP_LABEL (insn)
1596 to before INSN. If we are running before flow, they will
1597 be deleted if they aren't needed. But this doesn't work
1600 This is really a special-case of jump threading, anyway. The
1601 right thing to do is to replace this and jump threading with
1602 much simpler code in cse.
1604 This code has been turned off in the non-cc0 case in the
1608 else if (this_is_simplejump
1609 /* Safe to skip USE and CLOBBER insns here
1610 since they will not be deleted. */
1611 && (temp
= prev_active_insn (insn
))
1612 && no_labels_between_p (temp
, insn
)
1613 && GET_CODE (temp
) == INSN
1614 && GET_CODE (PATTERN (temp
)) == SET
1615 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1616 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1617 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1618 /* If we find that the next value tested is `x'
1619 (TEMP1 is the insn where this happens), win. */
1620 && GET_CODE (temp1
) == INSN
1621 && GET_CODE (PATTERN (temp1
)) == SET
1623 /* Does temp1 `tst' the value of x? */
1624 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1625 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1626 && (temp1
= next_nonnote_insn (temp1
))
1628 /* Does temp1 compare the value of x against zero? */
1629 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1630 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1631 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1632 == SET_DEST (PATTERN (temp
)))
1633 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1634 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1636 && condjump_p (temp1
))
1638 /* Get the if_then_else from the condjump. */
1639 rtx choice
= SET_SRC (PATTERN (temp1
));
1640 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1642 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1643 rtx val
= SET_SRC (PATTERN (temp
));
1645 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1649 if (cond
== const_true_rtx
)
1650 ultimate
= XEXP (choice
, 1);
1651 else if (cond
== const0_rtx
)
1652 ultimate
= XEXP (choice
, 2);
1656 if (ultimate
== pc_rtx
)
1657 ultimate
= get_label_after (temp1
);
1658 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1659 ultimate
= XEXP (ultimate
, 0);
1661 if (ultimate
&& JUMP_LABEL(insn
) != ultimate
)
1662 changed
|= redirect_jump (insn
, ultimate
);
1668 /* @@ This needs a bit of work before it will be right.
1670 Any type of comparison can be accepted for the first and
1671 second compare. When rewriting the first jump, we must
1672 compute the what conditions can reach label3, and use the
1673 appropriate code. We can not simply reverse/swap the code
1674 of the first jump. In some cases, the second jump must be
1678 < == converts to > ==
1679 < != converts to == >
1682 If the code is written to only accept an '==' test for the second
1683 compare, then all that needs to be done is to swap the condition
1684 of the first branch.
1686 It is questionable whether we want this optimization anyways,
1687 since if the user wrote code like this because he/she knew that
1688 the jump to label1 is taken most of the time, then rewriting
1689 this gives slower code. */
1690 /* @@ This should call get_condition to find the values being
1691 compared, instead of looking for a COMPARE insn when HAVE_cc0
1692 is not defined. This would allow it to work on the m88k. */
1693 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1694 is not defined and the condition is tested by a separate compare
1695 insn. This is because the code below assumes that the result
1696 of the compare dies in the following branch. */
1698 /* Simplify test a ~= b
1712 where ~= is an inequality, e.g. >, and ~~= is the swapped
1715 We recognize this case scanning backwards.
1717 TEMP is the conditional jump to `label2';
1718 TEMP1 is the test for `a == b';
1719 TEMP2 is the conditional jump to `label1';
1720 TEMP3 is the test for `a ~= b'. */
1721 else if (this_is_simplejump
1722 && (temp
= prev_active_insn (insn
))
1723 && no_labels_between_p (temp
, insn
)
1724 && condjump_p (temp
)
1725 && (temp1
= prev_active_insn (temp
))
1726 && no_labels_between_p (temp1
, temp
)
1727 && GET_CODE (temp1
) == INSN
1728 && GET_CODE (PATTERN (temp1
)) == SET
1730 && sets_cc0_p (PATTERN (temp1
)) == 1
1732 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1733 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1734 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1736 && (temp2
= prev_active_insn (temp1
))
1737 && no_labels_between_p (temp2
, temp1
)
1738 && condjump_p (temp2
)
1739 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1740 && (temp3
= prev_active_insn (temp2
))
1741 && no_labels_between_p (temp3
, temp2
)
1742 && GET_CODE (PATTERN (temp3
)) == SET
1743 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1744 SET_DEST (PATTERN (temp1
)))
1745 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1746 SET_SRC (PATTERN (temp3
)))
1747 && ! inequality_comparisons_p (PATTERN (temp
))
1748 && inequality_comparisons_p (PATTERN (temp2
)))
1750 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1752 ++LABEL_NUSES (fallthrough_label
);
1753 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1759 if (--LABEL_NUSES (fallthrough_label
) == 0)
1760 delete_insn (fallthrough_label
);
1763 /* Simplify if (...) {... x = 1;} if (x) ...
1765 We recognize this case backwards.
1767 TEMP is the test of `x';
1768 TEMP1 is the assignment to `x' at the end of the
1769 previous statement. */
1770 /* @@ This should call get_condition to find the values being
1771 compared, instead of looking for a COMPARE insn when HAVE_cc0
1772 is not defined. This would allow it to work on the m88k. */
1773 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1774 is not defined and the condition is tested by a separate compare
1775 insn. This is because the code below assumes that the result
1776 of the compare dies in the following branch. */
1778 /* ??? This has to be turned off. The problem is that the
1779 unconditional jump might indirectly end up branching to the
1780 label between TEMP1 and TEMP. We can't detect this, in general,
1781 since it may become a jump to there after further optimizations.
1782 If that jump is done, it will be deleted, so we will retry
1783 this optimization in the next pass, thus an infinite loop.
1785 The present code prevents this by putting the jump after the
1786 label, but this is not logically correct. */
1788 else if (this_is_condjump
1789 /* Safe to skip USE and CLOBBER insns here
1790 since they will not be deleted. */
1791 && (temp
= prev_active_insn (insn
))
1792 && no_labels_between_p (temp
, insn
)
1793 && GET_CODE (temp
) == INSN
1794 && GET_CODE (PATTERN (temp
)) == SET
1796 && sets_cc0_p (PATTERN (temp
)) == 1
1797 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1799 /* Temp must be a compare insn, we can not accept a register
1800 to register move here, since it may not be simply a
1802 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1803 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1804 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1805 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1806 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1808 /* May skip USE or CLOBBER insns here
1809 for checking for opportunity, since we
1810 take care of them later. */
1811 && (temp1
= prev_active_insn (temp
))
1812 && GET_CODE (temp1
) == INSN
1813 && GET_CODE (PATTERN (temp1
)) == SET
1815 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1817 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1818 == SET_DEST (PATTERN (temp1
)))
1820 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1821 /* If this isn't true, cse will do the job. */
1822 && ! no_labels_between_p (temp1
, temp
))
1824 /* Get the if_then_else from the condjump. */
1825 rtx choice
= SET_SRC (PATTERN (insn
));
1826 if (GET_CODE (choice
) == IF_THEN_ELSE
1827 && (GET_CODE (XEXP (choice
, 0)) == EQ
1828 || GET_CODE (XEXP (choice
, 0)) == NE
))
1830 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1835 /* Get the place that condjump will jump to
1836 if it is reached from here. */
1837 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1839 ultimate
= XEXP (choice
, 1);
1841 ultimate
= XEXP (choice
, 2);
1842 /* Get it as a CODE_LABEL. */
1843 if (ultimate
== pc_rtx
)
1844 ultimate
= get_label_after (insn
);
1846 /* Get the label out of the LABEL_REF. */
1847 ultimate
= XEXP (ultimate
, 0);
1849 /* Insert the jump immediately before TEMP, specifically
1850 after the label that is between TEMP1 and TEMP. */
1851 last_insn
= PREV_INSN (temp
);
1853 /* If we would be branching to the next insn, the jump
1854 would immediately be deleted and the re-inserted in
1855 a subsequent pass over the code. So don't do anything
1857 if (next_active_insn (last_insn
)
1858 != next_active_insn (ultimate
))
1860 emit_barrier_after (last_insn
);
1861 p
= emit_jump_insn_after (gen_jump (ultimate
),
1863 JUMP_LABEL (p
) = ultimate
;
1864 ++LABEL_NUSES (ultimate
);
1865 if (INSN_UID (ultimate
) < max_jump_chain
1866 && INSN_CODE (p
) < max_jump_chain
)
1868 jump_chain
[INSN_UID (p
)]
1869 = jump_chain
[INSN_UID (ultimate
)];
1870 jump_chain
[INSN_UID (ultimate
)] = p
;
1878 /* Detect a conditional jump going to the same place
1879 as an immediately following unconditional jump. */
1880 else if (this_is_condjump
1881 && (temp
= next_active_insn (insn
)) != 0
1882 && simplejump_p (temp
)
1883 && (next_active_insn (JUMP_LABEL (insn
))
1884 == next_active_insn (JUMP_LABEL (temp
))))
1888 /* ??? Optional. Disables some optimizations, but makes
1889 gcov output more accurate with -O. */
1890 if (flag_test_coverage
&& !reload_completed
)
1891 for (tem
= insn
; tem
!= temp
; tem
= NEXT_INSN (tem
))
1892 if (GET_CODE (tem
) == NOTE
&& NOTE_LINE_NUMBER (tem
) > 0)
1902 /* Detect a conditional jump jumping over an unconditional jump. */
1904 else if ((this_is_condjump
|| this_is_condjump_in_parallel
)
1905 && ! this_is_simplejump
1906 && reallabelprev
!= 0
1907 && GET_CODE (reallabelprev
) == JUMP_INSN
1908 && prev_active_insn (reallabelprev
) == insn
1909 && no_labels_between_p (insn
, reallabelprev
)
1910 && simplejump_p (reallabelprev
))
1912 /* When we invert the unconditional jump, we will be
1913 decrementing the usage count of its old label.
1914 Make sure that we don't delete it now because that
1915 might cause the following code to be deleted. */
1916 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
1917 rtx prev_label
= JUMP_LABEL (insn
);
1920 ++LABEL_NUSES (prev_label
);
1922 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
1924 /* It is very likely that if there are USE insns before
1925 this jump, they hold REG_DEAD notes. These REG_DEAD
1926 notes are no longer valid due to this optimization,
1927 and will cause the life-analysis that following passes
1928 (notably delayed-branch scheduling) to think that
1929 these registers are dead when they are not.
1931 To prevent this trouble, we just remove the USE insns
1932 from the insn chain. */
1934 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
1935 && GET_CODE (PATTERN (prev_uses
)) == USE
)
1937 rtx useless
= prev_uses
;
1938 prev_uses
= prev_nonnote_insn (prev_uses
);
1939 delete_insn (useless
);
1942 delete_insn (reallabelprev
);
1947 /* We can now safely delete the label if it is unreferenced
1948 since the delete_insn above has deleted the BARRIER. */
1949 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
1950 delete_insn (prev_label
);
1955 /* Detect a jump to a jump. */
1957 nlabel
= follow_jumps (JUMP_LABEL (insn
));
1958 if (nlabel
!= JUMP_LABEL (insn
)
1959 && redirect_jump (insn
, nlabel
))
1965 /* Look for if (foo) bar; else break; */
1966 /* The insns look like this:
1967 insn = condjump label1;
1968 ...range1 (some insns)...
1971 ...range2 (some insns)...
1972 jump somewhere unconditionally
1975 rtx label1
= next_label (insn
);
1976 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1977 /* Don't do this optimization on the first round, so that
1978 jump-around-a-jump gets simplified before we ask here
1979 whether a jump is unconditional.
1981 Also don't do it when we are called after reload since
1982 it will confuse reorg. */
1984 && (reload_completed
? ! flag_delayed_branch
: 1)
1985 /* Make sure INSN is something we can invert. */
1986 && condjump_p (insn
)
1988 && JUMP_LABEL (insn
) == label1
1989 && LABEL_NUSES (label1
) == 1
1990 && GET_CODE (range1end
) == JUMP_INSN
1991 && simplejump_p (range1end
))
1993 rtx label2
= next_label (label1
);
1994 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
1995 if (range1end
!= range2end
1996 && JUMP_LABEL (range1end
) == label2
1997 && GET_CODE (range2end
) == JUMP_INSN
1998 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
1999 /* Invert the jump condition, so we
2000 still execute the same insns in each case. */
2001 && invert_jump (insn
, label1
))
2003 rtx range1beg
= next_active_insn (insn
);
2004 rtx range2beg
= next_active_insn (label1
);
2005 rtx range1after
, range2after
;
2006 rtx range1before
, range2before
;
2009 /* Include in each range any notes before it, to be
2010 sure that we get the line number note if any, even
2011 if there are other notes here. */
2012 while (PREV_INSN (range1beg
)
2013 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
)
2014 range1beg
= PREV_INSN (range1beg
);
2016 while (PREV_INSN (range2beg
)
2017 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
)
2018 range2beg
= PREV_INSN (range2beg
);
2020 /* Don't move NOTEs for blocks or loops; shift them
2021 outside the ranges, where they'll stay put. */
2022 range1beg
= squeeze_notes (range1beg
, range1end
);
2023 range2beg
= squeeze_notes (range2beg
, range2end
);
2025 /* Get current surrounds of the 2 ranges. */
2026 range1before
= PREV_INSN (range1beg
);
2027 range2before
= PREV_INSN (range2beg
);
2028 range1after
= NEXT_INSN (range1end
);
2029 range2after
= NEXT_INSN (range2end
);
2031 /* Splice range2 where range1 was. */
2032 NEXT_INSN (range1before
) = range2beg
;
2033 PREV_INSN (range2beg
) = range1before
;
2034 NEXT_INSN (range2end
) = range1after
;
2035 PREV_INSN (range1after
) = range2end
;
2036 /* Splice range1 where range2 was. */
2037 NEXT_INSN (range2before
) = range1beg
;
2038 PREV_INSN (range1beg
) = range2before
;
2039 NEXT_INSN (range1end
) = range2after
;
2040 PREV_INSN (range2after
) = range1end
;
2042 /* Check for a loop end note between the end of
2043 range2, and the next code label. If there is one,
2044 then what we have really seen is
2045 if (foo) break; end_of_loop;
2046 and moved the break sequence outside the loop.
2047 We must move the LOOP_END note to where the
2048 loop really ends now, or we will confuse loop
2049 optimization. Stop if we find a LOOP_BEG note
2050 first, since we don't want to move the LOOP_END
2051 note in that case. */
2052 for (;range2after
!= label2
; range2after
= rangenext
)
2054 rangenext
= NEXT_INSN (range2after
);
2055 if (GET_CODE (range2after
) == NOTE
)
2057 if (NOTE_LINE_NUMBER (range2after
)
2058 == NOTE_INSN_LOOP_END
)
2060 NEXT_INSN (PREV_INSN (range2after
))
2062 PREV_INSN (rangenext
)
2063 = PREV_INSN (range2after
);
2064 PREV_INSN (range2after
)
2065 = PREV_INSN (range1beg
);
2066 NEXT_INSN (range2after
) = range1beg
;
2067 NEXT_INSN (PREV_INSN (range1beg
))
2069 PREV_INSN (range1beg
) = range2after
;
2071 else if (NOTE_LINE_NUMBER (range2after
)
2072 == NOTE_INSN_LOOP_BEG
)
2082 /* Now that the jump has been tensioned,
2083 try cross jumping: check for identical code
2084 before the jump and before its target label. */
2086 /* First, cross jumping of conditional jumps: */
2088 if (cross_jump
&& condjump_p (insn
))
2090 rtx newjpos
, newlpos
;
2091 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
2093 /* A conditional jump may be crossjumped
2094 only if the place it jumps to follows
2095 an opposing jump that comes back here. */
2097 if (x
!= 0 && ! jump_back_p (x
, insn
))
2098 /* We have no opposing jump;
2099 cannot cross jump this insn. */
2103 /* TARGET is nonzero if it is ok to cross jump
2104 to code before TARGET. If so, see if matches. */
2106 find_cross_jump (insn
, x
, 2,
2107 &newjpos
, &newlpos
);
2111 do_cross_jump (insn
, newjpos
, newlpos
);
2112 /* Make the old conditional jump
2113 into an unconditional one. */
2114 SET_SRC (PATTERN (insn
))
2115 = gen_rtx_LABEL_REF (VOIDmode
, JUMP_LABEL (insn
));
2116 INSN_CODE (insn
) = -1;
2117 emit_barrier_after (insn
);
2118 /* Add to jump_chain unless this is a new label
2119 whose UID is too large. */
2120 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
2122 jump_chain
[INSN_UID (insn
)]
2123 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
2124 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
2131 /* Cross jumping of unconditional jumps:
2132 a few differences. */
2134 if (cross_jump
&& simplejump_p (insn
))
2136 rtx newjpos
, newlpos
;
2141 /* TARGET is nonzero if it is ok to cross jump
2142 to code before TARGET. If so, see if matches. */
2143 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
2144 &newjpos
, &newlpos
);
2146 /* If cannot cross jump to code before the label,
2147 see if we can cross jump to another jump to
2149 /* Try each other jump to this label. */
2150 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
2151 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
2152 target
!= 0 && newjpos
== 0;
2153 target
= jump_chain
[INSN_UID (target
)])
2155 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
2156 /* Ignore TARGET if it's deleted. */
2157 && ! INSN_DELETED_P (target
))
2158 find_cross_jump (insn
, target
, 2,
2159 &newjpos
, &newlpos
);
2163 do_cross_jump (insn
, newjpos
, newlpos
);
2169 /* This code was dead in the previous jump.c! */
2170 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
2172 /* Return insns all "jump to the same place"
2173 so we can cross-jump between any two of them. */
2175 rtx newjpos
, newlpos
, target
;
2179 /* If cannot cross jump to code before the label,
2180 see if we can cross jump to another jump to
2182 /* Try each other jump to this label. */
2183 for (target
= jump_chain
[0];
2184 target
!= 0 && newjpos
== 0;
2185 target
= jump_chain
[INSN_UID (target
)])
2187 && ! INSN_DELETED_P (target
)
2188 && GET_CODE (PATTERN (target
)) == RETURN
)
2189 find_cross_jump (insn
, target
, 2,
2190 &newjpos
, &newlpos
);
2194 do_cross_jump (insn
, newjpos
, newlpos
);
2205 /* Delete extraneous line number notes.
2206 Note that two consecutive notes for different lines are not really
2207 extraneous. There should be some indication where that line belonged,
2208 even if it became empty. */
2213 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2214 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
2216 /* Delete this note if it is identical to previous note. */
2218 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
2219 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
2232 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2233 in front of it. If the machine allows it at this point (we might be
2234 after reload for a leaf routine), it will improve optimization for it
2235 to be there. We do this both here and at the start of this pass since
2236 the RETURN might have been deleted by some of our optimizations. */
2237 insn
= get_last_insn ();
2238 while (insn
&& GET_CODE (insn
) == NOTE
)
2239 insn
= PREV_INSN (insn
);
2241 if (insn
&& GET_CODE (insn
) != BARRIER
)
2243 emit_jump_insn (gen_return ());
2249 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2250 If so, delete it, and record that this function can drop off the end. */
2256 /* One label can follow the end-note: the return label. */
2257 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
2258 /* Ordinary insns can follow it if returning a structure. */
2259 || GET_CODE (insn
) == INSN
2260 /* If machine uses explicit RETURN insns, no epilogue,
2261 then one of them follows the note. */
2262 || (GET_CODE (insn
) == JUMP_INSN
2263 && GET_CODE (PATTERN (insn
)) == RETURN
)
2264 /* A barrier can follow the return insn. */
2265 || GET_CODE (insn
) == BARRIER
2266 /* Other kinds of notes can follow also. */
2267 || (GET_CODE (insn
) == NOTE
2268 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
2269 insn
= PREV_INSN (insn
);
2272 /* Report if control can fall through at the end of the function. */
2273 if (insn
&& GET_CODE (insn
) == NOTE
2274 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
)
2280 /* Show JUMP_CHAIN no longer valid. */
2284 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2285 jump. Assume that this unconditional jump is to the exit test code. If
2286 the code is sufficiently simple, make a copy of it before INSN,
2287 followed by a jump to the exit of the loop. Then delete the unconditional
2290 Return 1 if we made the change, else 0.
2292 This is only safe immediately after a regscan pass because it uses the
2293 values of regno_first_uid and regno_last_uid. */
2296 duplicate_loop_exit_test (loop_start
)
2299 rtx insn
, set
, reg
, p
, link
;
2302 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
2304 int max_reg
= max_reg_num ();
2307 /* Scan the exit code. We do not perform this optimization if any insn:
2311 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2312 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2313 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2316 Also, don't do this if the exit code is more than 20 insns. */
2318 for (insn
= exitcode
;
2320 && ! (GET_CODE (insn
) == NOTE
2321 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
2322 insn
= NEXT_INSN (insn
))
2324 switch (GET_CODE (insn
))
2330 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2331 a jump immediately after the loop start that branches outside
2332 the loop but within an outer loop, near the exit test.
2333 If we copied this exit test and created a phony
2334 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2335 before the exit test look like these could be safely moved
2336 out of the loop even if they actually may be never executed.
2337 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2339 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2340 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2341 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2342 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
)
2347 if (++num_insns
> 20
2348 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
2349 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2357 /* Unless INSN is zero, we can do the optimization. */
2363 /* See if any insn sets a register only used in the loop exit code and
2364 not a user variable. If so, replace it with a new register. */
2365 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2366 if (GET_CODE (insn
) == INSN
2367 && (set
= single_set (insn
)) != 0
2368 && ((reg
= SET_DEST (set
), GET_CODE (reg
) == REG
)
2369 || (GET_CODE (reg
) == SUBREG
2370 && (reg
= SUBREG_REG (reg
), GET_CODE (reg
) == REG
)))
2371 && REGNO (reg
) >= FIRST_PSEUDO_REGISTER
2372 && REGNO_FIRST_UID (REGNO (reg
)) == INSN_UID (insn
))
2374 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
2375 if (REGNO_LAST_UID (REGNO (reg
)) == INSN_UID (p
))
2380 /* We can do the replacement. Allocate reg_map if this is the
2381 first replacement we found. */
2384 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
2385 bzero ((char *) reg_map
, max_reg
* sizeof (rtx
));
2388 REG_LOOP_TEST_P (reg
) = 1;
2390 reg_map
[REGNO (reg
)] = gen_reg_rtx (GET_MODE (reg
));
2394 /* Now copy each insn. */
2395 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2396 switch (GET_CODE (insn
))
2399 copy
= emit_barrier_before (loop_start
);
2402 /* Only copy line-number notes. */
2403 if (NOTE_LINE_NUMBER (insn
) >= 0)
2405 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
2406 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
2411 copy
= emit_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2413 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2415 mark_jump_label (PATTERN (copy
), copy
, 0);
2417 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2419 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2420 if (REG_NOTE_KIND (link
) != REG_LABEL
)
2422 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link
),
2425 if (reg_map
&& REG_NOTES (copy
))
2426 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2430 copy
= emit_jump_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2432 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2433 mark_jump_label (PATTERN (copy
), copy
, 0);
2434 if (REG_NOTES (insn
))
2436 REG_NOTES (copy
) = copy_rtx (REG_NOTES (insn
));
2438 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2441 /* If this is a simple jump, add it to the jump chain. */
2443 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
2444 && simplejump_p (copy
))
2446 jump_chain
[INSN_UID (copy
)]
2447 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2448 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2456 /* Now clean up by emitting a jump to the end label and deleting the jump
2457 at the start of the loop. */
2458 if (! copy
|| GET_CODE (copy
) != BARRIER
)
2460 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
2462 mark_jump_label (PATTERN (copy
), copy
, 0);
2463 if (INSN_UID (copy
) < max_jump_chain
2464 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
2466 jump_chain
[INSN_UID (copy
)]
2467 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2468 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2470 emit_barrier_before (loop_start
);
2473 /* Mark the exit code as the virtual top of the converted loop. */
2474 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
2476 delete_insn (next_nonnote_insn (loop_start
));
2481 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2482 loop-end notes between START and END out before START. Assume that
2483 END is not such a note. START may be such a note. Returns the value
2484 of the new starting insn, which may be different if the original start
2488 squeeze_notes (start
, end
)
2494 for (insn
= start
; insn
!= end
; insn
= next
)
2496 next
= NEXT_INSN (insn
);
2497 if (GET_CODE (insn
) == NOTE
2498 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2499 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2500 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2501 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
2502 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
2503 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
2509 rtx prev
= PREV_INSN (insn
);
2510 PREV_INSN (insn
) = PREV_INSN (start
);
2511 NEXT_INSN (insn
) = start
;
2512 NEXT_INSN (PREV_INSN (insn
)) = insn
;
2513 PREV_INSN (NEXT_INSN (insn
)) = insn
;
2514 NEXT_INSN (prev
) = next
;
2515 PREV_INSN (next
) = prev
;
2523 /* Compare the instructions before insn E1 with those before E2
2524 to find an opportunity for cross jumping.
2525 (This means detecting identical sequences of insns followed by
2526 jumps to the same place, or followed by a label and a jump
2527 to that label, and replacing one with a jump to the other.)
2529 Assume E1 is a jump that jumps to label E2
2530 (that is not always true but it might as well be).
2531 Find the longest possible equivalent sequences
2532 and store the first insns of those sequences into *F1 and *F2.
2533 Store zero there if no equivalent preceding instructions are found.
2535 We give up if we find a label in stream 1.
2536 Actually we could transfer that label into stream 2. */
2539 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
2544 register rtx i1
= e1
, i2
= e2
;
2545 register rtx p1
, p2
;
2548 rtx last1
= 0, last2
= 0;
2549 rtx afterlast1
= 0, afterlast2
= 0;
2557 i1
= prev_nonnote_insn (i1
);
2559 i2
= PREV_INSN (i2
);
2560 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
2561 i2
= PREV_INSN (i2
);
2566 /* Don't allow the range of insns preceding E1 or E2
2567 to include the other (E2 or E1). */
2568 if (i2
== e1
|| i1
== e2
)
2571 /* If we will get to this code by jumping, those jumps will be
2572 tensioned to go directly to the new label (before I2),
2573 so this cross-jumping won't cost extra. So reduce the minimum. */
2574 if (GET_CODE (i1
) == CODE_LABEL
)
2580 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
2586 /* If this is a CALL_INSN, compare register usage information.
2587 If we don't check this on stack register machines, the two
2588 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2589 numbers of stack registers in the same basic block.
2590 If we don't check this on machines with delay slots, a delay slot may
2591 be filled that clobbers a parameter expected by the subroutine.
2593 ??? We take the simple route for now and assume that if they're
2594 equal, they were constructed identically. */
2596 if (GET_CODE (i1
) == CALL_INSN
2597 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1
),
2598 CALL_INSN_FUNCTION_USAGE (i2
)))
2602 /* If cross_jump_death_matters is not 0, the insn's mode
2603 indicates whether or not the insn contains any stack-like
2606 if (!lose
&& cross_jump_death_matters
&& GET_MODE (i1
) == QImode
)
2608 /* If register stack conversion has already been done, then
2609 death notes must also be compared before it is certain that
2610 the two instruction streams match. */
2613 HARD_REG_SET i1_regset
, i2_regset
;
2615 CLEAR_HARD_REG_SET (i1_regset
);
2616 CLEAR_HARD_REG_SET (i2_regset
);
2618 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
2619 if (REG_NOTE_KIND (note
) == REG_DEAD
2620 && STACK_REG_P (XEXP (note
, 0)))
2621 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
2623 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
2624 if (REG_NOTE_KIND (note
) == REG_DEAD
2625 && STACK_REG_P (XEXP (note
, 0)))
2626 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
2628 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
2637 /* Don't allow old-style asm or volatile extended asms to be accepted
2638 for cross jumping purposes. It is conceptually correct to allow
2639 them, since cross-jumping preserves the dynamic instruction order
2640 even though it is changing the static instruction order. However,
2641 if an asm is being used to emit an assembler pseudo-op, such as
2642 the MIPS `.set reorder' pseudo-op, then the static instruction order
2643 matters and it must be preserved. */
2644 if (GET_CODE (p1
) == ASM_INPUT
|| GET_CODE (p2
) == ASM_INPUT
2645 || (GET_CODE (p1
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p1
))
2646 || (GET_CODE (p2
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p2
)))
2649 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
2650 || ! rtx_renumbered_equal_p (p1
, p2
))
2652 /* The following code helps take care of G++ cleanups. */
2656 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
2657 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
2658 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
2659 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
2660 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
2661 /* If the equivalences are not to a constant, they may
2662 reference pseudos that no longer exist, so we can't
2664 && CONSTANT_P (XEXP (equiv1
, 0))
2665 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
2667 rtx s1
= single_set (i1
);
2668 rtx s2
= single_set (i2
);
2669 if (s1
!= 0 && s2
!= 0
2670 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
2672 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
2673 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
2674 if (! rtx_renumbered_equal_p (p1
, p2
))
2676 else if (apply_change_group ())
2681 /* Insns fail to match; cross jumping is limited to the following
2685 /* Don't allow the insn after a compare to be shared by
2686 cross-jumping unless the compare is also shared.
2687 Here, if either of these non-matching insns is a compare,
2688 exclude the following insn from possible cross-jumping. */
2689 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
2690 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
2693 /* If cross-jumping here will feed a jump-around-jump
2694 optimization, this jump won't cost extra, so reduce
2696 if (GET_CODE (i1
) == JUMP_INSN
2698 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
2704 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
2706 /* Ok, this insn is potentially includable in a cross-jump here. */
2707 afterlast1
= last1
, afterlast2
= last2
;
2708 last1
= i1
, last2
= i2
, --minimum
;
2712 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
2713 *f1
= last1
, *f2
= last2
;
2717 do_cross_jump (insn
, newjpos
, newlpos
)
2718 rtx insn
, newjpos
, newlpos
;
2720 /* Find an existing label at this point
2721 or make a new one if there is none. */
2722 register rtx label
= get_label_before (newlpos
);
2724 /* Make the same jump insn jump to the new point. */
2725 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2727 /* Remove from jump chain of returns. */
2728 delete_from_jump_chain (insn
);
2729 /* Change the insn. */
2730 PATTERN (insn
) = gen_jump (label
);
2731 INSN_CODE (insn
) = -1;
2732 JUMP_LABEL (insn
) = label
;
2733 LABEL_NUSES (label
)++;
2734 /* Add to new the jump chain. */
2735 if (INSN_UID (label
) < max_jump_chain
2736 && INSN_UID (insn
) < max_jump_chain
)
2738 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
2739 jump_chain
[INSN_UID (label
)] = insn
;
2743 redirect_jump (insn
, label
);
2745 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2746 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2747 the NEWJPOS stream. */
2749 while (newjpos
!= insn
)
2753 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
2754 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
2755 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
2756 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
2757 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
2758 remove_note (newlpos
, lnote
);
2760 delete_insn (newjpos
);
2761 newjpos
= next_real_insn (newjpos
);
2762 newlpos
= next_real_insn (newlpos
);
2766 /* Return the label before INSN, or put a new label there. */
2769 get_label_before (insn
)
2774 /* Find an existing label at this point
2775 or make a new one if there is none. */
2776 label
= prev_nonnote_insn (insn
);
2778 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2780 rtx prev
= PREV_INSN (insn
);
2782 label
= gen_label_rtx ();
2783 emit_label_after (label
, prev
);
2784 LABEL_NUSES (label
) = 0;
2789 /* Return the label after INSN, or put a new label there. */
2792 get_label_after (insn
)
2797 /* Find an existing label at this point
2798 or make a new one if there is none. */
2799 label
= next_nonnote_insn (insn
);
2801 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2803 label
= gen_label_rtx ();
2804 emit_label_after (label
, insn
);
2805 LABEL_NUSES (label
) = 0;
2810 /* Return 1 if INSN is a jump that jumps to right after TARGET
2811 only on the condition that TARGET itself would drop through.
2812 Assumes that TARGET is a conditional jump. */
2815 jump_back_p (insn
, target
)
2819 enum rtx_code codei
, codet
;
2821 if (simplejump_p (insn
) || ! condjump_p (insn
)
2822 || simplejump_p (target
)
2823 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
2826 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
2827 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
2829 codei
= GET_CODE (cinsn
);
2830 codet
= GET_CODE (ctarget
);
2832 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
2834 if (! can_reverse_comparison_p (cinsn
, insn
))
2836 codei
= reverse_condition (codei
);
2839 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
2841 if (! can_reverse_comparison_p (ctarget
, target
))
2843 codet
= reverse_condition (codet
);
2846 return (codei
== codet
2847 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
2848 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
2851 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2852 return non-zero if it is safe to reverse this comparison. It is if our
2853 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2854 this is known to be an integer comparison. */
2857 can_reverse_comparison_p (comparison
, insn
)
2863 /* If this is not actually a comparison, we can't reverse it. */
2864 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
2867 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
2868 /* If this is an NE comparison, it is safe to reverse it to an EQ
2869 comparison and vice versa, even for floating point. If no operands
2870 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2871 always false and NE is always true, so the reversal is also valid. */
2873 || GET_CODE (comparison
) == NE
2874 || GET_CODE (comparison
) == EQ
)
2877 arg0
= XEXP (comparison
, 0);
2879 /* Make sure ARG0 is one of the actual objects being compared. If we
2880 can't do this, we can't be sure the comparison can be reversed.
2882 Handle cc0 and a MODE_CC register. */
2883 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
2889 rtx prev
= prev_nonnote_insn (insn
);
2890 rtx set
= single_set (prev
);
2892 if (set
== 0 || SET_DEST (set
) != arg0
)
2895 arg0
= SET_SRC (set
);
2897 if (GET_CODE (arg0
) == COMPARE
)
2898 arg0
= XEXP (arg0
, 0);
2901 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2902 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2903 return (GET_CODE (arg0
) == CONST_INT
2904 || (GET_MODE (arg0
) != VOIDmode
2905 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
2906 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
2909 /* Given an rtx-code for a comparison, return the code
2910 for the negated comparison.
2911 WATCH OUT! reverse_condition is not safe to use on a jump
2912 that might be acting on the results of an IEEE floating point comparison,
2913 because of the special treatment of non-signaling nans in comparisons.
2914 Use can_reverse_comparison_p to be sure. */
2917 reverse_condition (code
)
2958 /* Similar, but return the code when two operands of a comparison are swapped.
2959 This IS safe for IEEE floating-point. */
2962 swap_condition (code
)
3001 /* Given a comparison CODE, return the corresponding unsigned comparison.
3002 If CODE is an equality comparison or already an unsigned comparison,
3003 CODE is returned. */
3006 unsigned_condition (code
)
3036 /* Similarly, return the signed version of a comparison. */
3039 signed_condition (code
)
3069 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3070 truth of CODE1 implies the truth of CODE2. */
3073 comparison_dominates_p (code1
, code2
)
3074 enum rtx_code code1
, code2
;
3082 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
3087 if (code2
== LE
|| code2
== NE
)
3092 if (code2
== GE
|| code2
== NE
)
3097 if (code2
== LEU
|| code2
== NE
)
3102 if (code2
== GEU
|| code2
== NE
)
3113 /* Return 1 if INSN is an unconditional jump and nothing else. */
3119 return (GET_CODE (insn
) == JUMP_INSN
3120 && GET_CODE (PATTERN (insn
)) == SET
3121 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
3122 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
3125 /* Return nonzero if INSN is a (possibly) conditional jump
3126 and nothing more. */
3132 register rtx x
= PATTERN (insn
);
3133 if (GET_CODE (x
) != SET
)
3135 if (GET_CODE (SET_DEST (x
)) != PC
)
3137 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
3139 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
3141 if (XEXP (SET_SRC (x
), 2) == pc_rtx
3142 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
3143 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
3145 if (XEXP (SET_SRC (x
), 1) == pc_rtx
3146 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
3147 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
3152 /* Return nonzero if INSN is a (possibly) conditional jump
3153 and nothing more. */
3156 condjump_in_parallel_p (insn
)
3159 register rtx x
= PATTERN (insn
);
3161 if (GET_CODE (x
) != PARALLEL
)
3164 x
= XVECEXP (x
, 0, 0);
3166 if (GET_CODE (x
) != SET
)
3168 if (GET_CODE (SET_DEST (x
)) != PC
)
3170 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
3172 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
3174 if (XEXP (SET_SRC (x
), 2) == pc_rtx
3175 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
3176 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
3178 if (XEXP (SET_SRC (x
), 1) == pc_rtx
3179 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
3180 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
3185 /* Return 1 if X is an RTX that does nothing but set the condition codes
3186 and CLOBBER or USE registers.
3187 Return -1 if X does explicitly set the condition codes,
3188 but also does other things. */
3195 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
3197 if (GET_CODE (x
) == PARALLEL
)
3201 int other_things
= 0;
3202 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
3204 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
3205 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
3207 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
3210 return ! sets_cc0
? 0 : other_things
? -1 : 1;
3218 /* Follow any unconditional jump at LABEL;
3219 return the ultimate label reached by any such chain of jumps.
3220 If LABEL is not followed by a jump, return LABEL.
3221 If the chain loops or we can't find end, return LABEL,
3222 since that tells caller to avoid changing the insn.
3224 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3225 a USE or CLOBBER. */
3228 follow_jumps (label
)
3233 register rtx value
= label
;
3238 && (insn
= next_active_insn (value
)) != 0
3239 && GET_CODE (insn
) == JUMP_INSN
3240 && ((JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
3241 || GET_CODE (PATTERN (insn
)) == RETURN
)
3242 && (next
= NEXT_INSN (insn
))
3243 && GET_CODE (next
) == BARRIER
);
3246 /* Don't chain through the insn that jumps into a loop
3247 from outside the loop,
3248 since that would create multiple loop entry jumps
3249 and prevent loop optimization. */
3251 if (!reload_completed
)
3252 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
3253 if (GET_CODE (tem
) == NOTE
3254 && (NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
3255 /* ??? Optional. Disables some optimizations, but makes
3256 gcov output more accurate with -O. */
3257 || (flag_test_coverage
&& NOTE_LINE_NUMBER (tem
) > 0)))
3260 /* If we have found a cycle, make the insn jump to itself. */
3261 if (JUMP_LABEL (insn
) == label
)
3264 tem
= next_active_insn (JUMP_LABEL (insn
));
3265 if (tem
&& (GET_CODE (PATTERN (tem
)) == ADDR_VEC
3266 || GET_CODE (PATTERN (tem
)) == ADDR_DIFF_VEC
))
3269 value
= JUMP_LABEL (insn
);
3276 /* Assuming that field IDX of X is a vector of label_refs,
3277 replace each of them by the ultimate label reached by it.
3278 Return nonzero if a change is made.
3279 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3282 tension_vector_labels (x
, idx
)
3288 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
3290 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
3291 register rtx nlabel
= follow_jumps (olabel
);
3292 if (nlabel
&& nlabel
!= olabel
)
3294 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
3295 ++LABEL_NUSES (nlabel
);
3296 if (--LABEL_NUSES (olabel
) == 0)
3297 delete_insn (olabel
);
3304 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3305 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3306 in INSN, then store one of them in JUMP_LABEL (INSN).
3307 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3308 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3309 Also, when there are consecutive labels, canonicalize on the last of them.
3311 Note that two labels separated by a loop-beginning note
3312 must be kept distinct if we have not yet done loop-optimization,
3313 because the gap between them is where loop-optimize
3314 will want to move invariant code to. CROSS_JUMP tells us
3315 that loop-optimization is done with.
3317 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3318 two labels distinct if they are separated by only USE or CLOBBER insns. */
3321 mark_jump_label (x
, insn
, cross_jump
)
3326 register RTX_CODE code
= GET_CODE (x
);
3344 /* If this is a constant-pool reference, see if it is a label. */
3345 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3346 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3347 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
3352 rtx label
= XEXP (x
, 0);
3357 if (GET_CODE (label
) != CODE_LABEL
)
3360 /* Ignore references to labels of containing functions. */
3361 if (LABEL_REF_NONLOCAL_P (x
))
3364 /* If there are other labels following this one,
3365 replace it with the last of the consecutive labels. */
3366 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
3368 if (GET_CODE (next
) == CODE_LABEL
)
3370 else if (cross_jump
&& GET_CODE (next
) == INSN
3371 && (GET_CODE (PATTERN (next
)) == USE
3372 || GET_CODE (PATTERN (next
)) == CLOBBER
))
3374 else if (GET_CODE (next
) != NOTE
)
3376 else if (! cross_jump
3377 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
3378 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
3379 /* ??? Optional. Disables some optimizations, but
3380 makes gcov output more accurate with -O. */
3381 || (flag_test_coverage
&& NOTE_LINE_NUMBER (next
) > 0)))
3385 XEXP (x
, 0) = label
;
3386 ++LABEL_NUSES (label
);
3390 if (GET_CODE (insn
) == JUMP_INSN
)
3391 JUMP_LABEL (insn
) = label
;
3393 /* If we've changed OLABEL and we had a REG_LABEL note
3394 for it, update it as well. */
3395 else if (label
!= olabel
3396 && (note
= find_reg_note (insn
, REG_LABEL
, olabel
)) != 0)
3397 XEXP (note
, 0) = label
;
3399 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3401 else if (! find_reg_note (insn
, REG_LABEL
, label
))
3403 rtx next
= next_real_insn (label
);
3404 /* Don't record labels that refer to dispatch tables.
3405 This is not necessary, since the tablejump
3406 references the same label.
3407 And if we did record them, flow.c would make worse code. */
3409 || ! (GET_CODE (next
) == JUMP_INSN
3410 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
3411 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
)))
3412 REG_NOTES (insn
) = gen_rtx_EXPR_LIST (REG_LABEL
, label
,
3419 /* Do walk the labels in a vector, but not the first operand of an
3420 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3424 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
3426 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
3427 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
, cross_jump
);
3435 fmt
= GET_RTX_FORMAT (code
);
3436 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3439 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
3440 else if (fmt
[i
] == 'E')
3443 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3444 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
3449 /* If all INSN does is set the pc, delete it,
3450 and delete the insn that set the condition codes for it
3451 if that's what the previous thing was. */
3457 register rtx set
= single_set (insn
);
3459 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3460 delete_computation (insn
);
3463 /* Delete INSN and recursively delete insns that compute values used only
3464 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3465 If we are running before flow.c, we need do nothing since flow.c will
3466 delete dead code. We also can't know if the registers being used are
3467 dead or not at this point.
3469 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3470 nothing other than set a register that dies in this insn, we can delete
3473 On machines with CC0, if CC0 is used in this insn, we may be able to
3474 delete the insn that set it. */
3477 delete_computation (insn
)
3483 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
3485 rtx prev
= prev_nonnote_insn (insn
);
3486 /* We assume that at this stage
3487 CC's are always set explicitly
3488 and always immediately before the jump that
3489 will use them. So if the previous insn
3490 exists to set the CC's, delete it
3491 (unless it performs auto-increments, etc.). */
3492 if (prev
&& GET_CODE (prev
) == INSN
3493 && sets_cc0_p (PATTERN (prev
)))
3495 if (sets_cc0_p (PATTERN (prev
)) > 0
3496 && !FIND_REG_INC_NOTE (prev
, NULL_RTX
))
3497 delete_computation (prev
);
3499 /* Otherwise, show that cc0 won't be used. */
3500 REG_NOTES (prev
) = gen_rtx_EXPR_LIST (REG_UNUSED
,
3501 cc0_rtx
, REG_NOTES (prev
));
3506 for (note
= REG_NOTES (insn
); note
; note
= next
)
3510 next
= XEXP (note
, 1);
3512 if (REG_NOTE_KIND (note
) != REG_DEAD
3513 /* Verify that the REG_NOTE is legitimate. */
3514 || GET_CODE (XEXP (note
, 0)) != REG
)
3517 for (our_prev
= prev_nonnote_insn (insn
);
3518 our_prev
&& GET_CODE (our_prev
) == INSN
;
3519 our_prev
= prev_nonnote_insn (our_prev
))
3521 /* If we reach a SEQUENCE, it is too complex to try to
3522 do anything with it, so give up. */
3523 if (GET_CODE (PATTERN (our_prev
)) == SEQUENCE
)
3526 if (GET_CODE (PATTERN (our_prev
)) == USE
3527 && GET_CODE (XEXP (PATTERN (our_prev
), 0)) == INSN
)
3528 /* reorg creates USEs that look like this. We leave them
3529 alone because reorg needs them for its own purposes. */
3532 if (reg_set_p (XEXP (note
, 0), PATTERN (our_prev
)))
3534 if (FIND_REG_INC_NOTE (our_prev
, NULL_RTX
))
3537 if (GET_CODE (PATTERN (our_prev
)) == PARALLEL
)
3539 /* If we find a SET of something else, we can't
3544 for (i
= 0; i
< XVECLEN (PATTERN (our_prev
), 0); i
++)
3546 rtx part
= XVECEXP (PATTERN (our_prev
), 0, i
);
3548 if (GET_CODE (part
) == SET
3549 && SET_DEST (part
) != XEXP (note
, 0))
3553 if (i
== XVECLEN (PATTERN (our_prev
), 0))
3554 delete_computation (our_prev
);
3556 else if (GET_CODE (PATTERN (our_prev
)) == SET
3557 && SET_DEST (PATTERN (our_prev
)) == XEXP (note
, 0))
3558 delete_computation (our_prev
);
3563 /* If OUR_PREV references the register that dies here, it is an
3564 additional use. Hence any prior SET isn't dead. However, this
3565 insn becomes the new place for the REG_DEAD note. */
3566 if (reg_overlap_mentioned_p (XEXP (note
, 0),
3567 PATTERN (our_prev
)))
3569 XEXP (note
, 1) = REG_NOTES (our_prev
);
3570 REG_NOTES (our_prev
) = note
;
3579 /* Delete insn INSN from the chain of insns and update label ref counts.
3580 May delete some following insns as a consequence; may even delete
3581 a label elsewhere and insns that follow it.
3583 Returns the first insn after INSN that was not deleted. */
3589 register rtx next
= NEXT_INSN (insn
);
3590 register rtx prev
= PREV_INSN (insn
);
3591 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
3592 register int dont_really_delete
= 0;
3594 while (next
&& INSN_DELETED_P (next
))
3595 next
= NEXT_INSN (next
);
3597 /* This insn is already deleted => return first following nondeleted. */
3598 if (INSN_DELETED_P (insn
))
3601 /* Don't delete user-declared labels. Convert them to special NOTEs
3603 if (was_code_label
&& LABEL_NAME (insn
) != 0
3604 && optimize
&& ! dont_really_delete
)
3606 PUT_CODE (insn
, NOTE
);
3607 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
3608 NOTE_SOURCE_FILE (insn
) = 0;
3609 dont_really_delete
= 1;
3612 /* Mark this insn as deleted. */
3613 INSN_DELETED_P (insn
) = 1;
3615 /* If this is an unconditional jump, delete it from the jump chain. */
3616 if (simplejump_p (insn
))
3617 delete_from_jump_chain (insn
);
3619 /* If instruction is followed by a barrier,
3620 delete the barrier too. */
3622 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
3624 INSN_DELETED_P (next
) = 1;
3625 next
= NEXT_INSN (next
);
3628 /* Patch out INSN (and the barrier if any) */
3630 if (optimize
&& ! dont_really_delete
)
3634 NEXT_INSN (prev
) = next
;
3635 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
3636 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
3637 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
3642 PREV_INSN (next
) = prev
;
3643 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
3644 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
3647 if (prev
&& NEXT_INSN (prev
) == 0)
3648 set_last_insn (prev
);
3651 /* If deleting a jump, decrement the count of the label,
3652 and delete the label if it is now unused. */
3654 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
3655 if (--LABEL_NUSES (JUMP_LABEL (insn
)) == 0)
3657 /* This can delete NEXT or PREV,
3658 either directly if NEXT is JUMP_LABEL (INSN),
3659 or indirectly through more levels of jumps. */
3660 delete_insn (JUMP_LABEL (insn
));
3661 /* I feel a little doubtful about this loop,
3662 but I see no clean and sure alternative way
3663 to find the first insn after INSN that is not now deleted.
3664 I hope this works. */
3665 while (next
&& INSN_DELETED_P (next
))
3666 next
= NEXT_INSN (next
);
3670 /* Likewise if we're deleting a dispatch table. */
3672 if (GET_CODE (insn
) == JUMP_INSN
3673 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
3674 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
3676 rtx pat
= PATTERN (insn
);
3677 int i
, diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
3678 int len
= XVECLEN (pat
, diff_vec_p
);
3680 for (i
= 0; i
< len
; i
++)
3681 if (--LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)) == 0)
3682 delete_insn (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0));
3683 while (next
&& INSN_DELETED_P (next
))
3684 next
= NEXT_INSN (next
);
3688 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
3689 prev
= PREV_INSN (prev
);
3691 /* If INSN was a label and a dispatch table follows it,
3692 delete the dispatch table. The tablejump must have gone already.
3693 It isn't useful to fall through into a table. */
3696 && NEXT_INSN (insn
) != 0
3697 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
3698 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
3699 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
3700 next
= delete_insn (NEXT_INSN (insn
));
3702 /* If INSN was a label, delete insns following it if now unreachable. */
3704 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
3706 register RTX_CODE code
;
3708 && (GET_RTX_CLASS (code
= GET_CODE (next
)) == 'i'
3709 || code
== NOTE
|| code
== BARRIER
3710 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
3713 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
3714 next
= NEXT_INSN (next
);
3715 /* Keep going past other deleted labels to delete what follows. */
3716 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
3717 next
= NEXT_INSN (next
);
3719 /* Note: if this deletes a jump, it can cause more
3720 deletion of unreachable code, after a different label.
3721 As long as the value from this recursive call is correct,
3722 this invocation functions correctly. */
3723 next
= delete_insn (next
);
3730 /* Advance from INSN till reaching something not deleted
3731 then return that. May return INSN itself. */
3734 next_nondeleted_insn (insn
)
3737 while (INSN_DELETED_P (insn
))
3738 insn
= NEXT_INSN (insn
);
3742 /* Delete a range of insns from FROM to TO, inclusive.
3743 This is for the sake of peephole optimization, so assume
3744 that whatever these insns do will still be done by a new
3745 peephole insn that will replace them. */
3748 delete_for_peephole (from
, to
)
3749 register rtx from
, to
;
3751 register rtx insn
= from
;
3755 register rtx next
= NEXT_INSN (insn
);
3756 register rtx prev
= PREV_INSN (insn
);
3758 if (GET_CODE (insn
) != NOTE
)
3760 INSN_DELETED_P (insn
) = 1;
3762 /* Patch this insn out of the chain. */
3763 /* We don't do this all at once, because we
3764 must preserve all NOTEs. */
3766 NEXT_INSN (prev
) = next
;
3769 PREV_INSN (next
) = prev
;
3777 /* Note that if TO is an unconditional jump
3778 we *do not* delete the BARRIER that follows,
3779 since the peephole that replaces this sequence
3780 is also an unconditional jump in that case. */
3783 /* Invert the condition of the jump JUMP, and make it jump
3784 to label NLABEL instead of where it jumps now. */
3787 invert_jump (jump
, nlabel
)
3790 /* We have to either invert the condition and change the label or
3791 do neither. Either operation could fail. We first try to invert
3792 the jump. If that succeeds, we try changing the label. If that fails,
3793 we invert the jump back to what it was. */
3795 if (! invert_exp (PATTERN (jump
), jump
))
3798 if (redirect_jump (jump
, nlabel
))
3800 if (flag_branch_probabilities
)
3802 rtx note
= find_reg_note (jump
, REG_BR_PROB
, 0);
3804 /* An inverted jump means that a probability taken becomes a
3805 probability not taken. Subtract the branch probability from the
3806 probability base to convert it back to a taken probability.
3807 (We don't flip the probability on a branch that's never taken. */
3808 if (note
&& XINT (XEXP (note
, 0), 0) >= 0)
3809 XINT (XEXP (note
, 0), 0) = REG_BR_PROB_BASE
- XINT (XEXP (note
, 0), 0);
3815 if (! invert_exp (PATTERN (jump
), jump
))
3816 /* This should just be putting it back the way it was. */
3822 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3824 Return 1 if we can do so, 0 if we cannot find a way to do so that
3825 matches a pattern. */
3828 invert_exp (x
, insn
)
3832 register RTX_CODE code
;
3836 code
= GET_CODE (x
);
3838 if (code
== IF_THEN_ELSE
)
3840 register rtx comp
= XEXP (x
, 0);
3843 /* We can do this in two ways: The preferable way, which can only
3844 be done if this is not an integer comparison, is to reverse
3845 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3846 of the IF_THEN_ELSE. If we can't do either, fail. */
3848 if (can_reverse_comparison_p (comp
, insn
)
3849 && validate_change (insn
, &XEXP (x
, 0),
3850 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp
)),
3851 GET_MODE (comp
), XEXP (comp
, 0),
3852 XEXP (comp
, 1)), 0))
3856 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
3857 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
3858 return apply_change_group ();
3861 fmt
= GET_RTX_FORMAT (code
);
3862 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3865 if (! invert_exp (XEXP (x
, i
), insn
))
3870 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3871 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
3879 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3880 If the old jump target label is unused as a result,
3881 it and the code following it may be deleted.
3883 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3886 The return value will be 1 if the change was made, 0 if it wasn't (this
3887 can only occur for NLABEL == 0). */
3890 redirect_jump (jump
, nlabel
)
3893 register rtx olabel
= JUMP_LABEL (jump
);
3895 if (nlabel
== olabel
)
3898 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
3901 /* If this is an unconditional branch, delete it from the jump_chain of
3902 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3903 have UID's in range and JUMP_CHAIN is valid). */
3904 if (jump_chain
&& (simplejump_p (jump
)
3905 || GET_CODE (PATTERN (jump
)) == RETURN
))
3907 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
3909 delete_from_jump_chain (jump
);
3910 if (label_index
< max_jump_chain
3911 && INSN_UID (jump
) < max_jump_chain
)
3913 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
3914 jump_chain
[label_index
] = jump
;
3918 JUMP_LABEL (jump
) = nlabel
;
3920 ++LABEL_NUSES (nlabel
);
3922 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
3923 delete_insn (olabel
);
3928 /* Delete the instruction JUMP from any jump chain it might be on. */
3931 delete_from_jump_chain (jump
)
3935 rtx olabel
= JUMP_LABEL (jump
);
3937 /* Handle unconditional jumps. */
3938 if (jump_chain
&& olabel
!= 0
3939 && INSN_UID (olabel
) < max_jump_chain
3940 && simplejump_p (jump
))
3941 index
= INSN_UID (olabel
);
3942 /* Handle return insns. */
3943 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
3947 if (jump_chain
[index
] == jump
)
3948 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
3953 for (insn
= jump_chain
[index
];
3955 insn
= jump_chain
[INSN_UID (insn
)])
3956 if (jump_chain
[INSN_UID (insn
)] == jump
)
3958 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
3964 /* If NLABEL is nonzero, throughout the rtx at LOC,
3965 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3966 zero, alter (RETURN) to (LABEL_REF NLABEL).
3968 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3969 validity with validate_change. Convert (set (pc) (label_ref olabel))
3972 Return 0 if we found a change we would like to make but it is invalid.
3973 Otherwise, return 1. */
3976 redirect_exp (loc
, olabel
, nlabel
, insn
)
3981 register rtx x
= *loc
;
3982 register RTX_CODE code
= GET_CODE (x
);
3986 if (code
== LABEL_REF
)
3988 if (XEXP (x
, 0) == olabel
)
3991 XEXP (x
, 0) = nlabel
;
3993 return validate_change (insn
, loc
, gen_rtx_RETURN (VOIDmode
), 0);
3997 else if (code
== RETURN
&& olabel
== 0)
3999 x
= gen_rtx_LABEL_REF (VOIDmode
, nlabel
);
4000 if (loc
== &PATTERN (insn
))
4001 x
= gen_rtx_SET (VOIDmode
, pc_rtx
, x
);
4002 return validate_change (insn
, loc
, x
, 0);
4005 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
4006 && GET_CODE (SET_SRC (x
)) == LABEL_REF
4007 && XEXP (SET_SRC (x
), 0) == olabel
)
4008 return validate_change (insn
, loc
, gen_rtx_RETURN (VOIDmode
), 0);
4010 fmt
= GET_RTX_FORMAT (code
);
4011 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4014 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
4019 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4020 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
4028 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4030 If the old jump target label (before the dispatch table) becomes unused,
4031 it and the dispatch table may be deleted. In that case, find the insn
4032 before the jump references that label and delete it and logical successors
4036 redirect_tablejump (jump
, nlabel
)
4039 register rtx olabel
= JUMP_LABEL (jump
);
4041 /* Add this jump to the jump_chain of NLABEL. */
4042 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
4043 && INSN_UID (jump
) < max_jump_chain
)
4045 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
4046 jump_chain
[INSN_UID (nlabel
)] = jump
;
4049 PATTERN (jump
) = gen_jump (nlabel
);
4050 JUMP_LABEL (jump
) = nlabel
;
4051 ++LABEL_NUSES (nlabel
);
4052 INSN_CODE (jump
) = -1;
4054 if (--LABEL_NUSES (olabel
) == 0)
4056 delete_labelref_insn (jump
, olabel
, 0);
4057 delete_insn (olabel
);
4061 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4062 If we found one, delete it and then delete this insn if DELETE_THIS is
4063 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4066 delete_labelref_insn (insn
, label
, delete_this
)
4073 if (GET_CODE (insn
) != NOTE
4074 && reg_mentioned_p (label
, PATTERN (insn
)))
4085 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
4086 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
4100 /* Like rtx_equal_p except that it considers two REGs as equal
4101 if they renumber to the same value and considers two commutative
4102 operations to be the same if the order of the operands has been
4106 rtx_renumbered_equal_p (x
, y
)
4110 register RTX_CODE code
= GET_CODE (x
);
4116 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
4117 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
4118 && GET_CODE (SUBREG_REG (y
)) == REG
)))
4120 int reg_x
= -1, reg_y
= -1;
4121 int word_x
= 0, word_y
= 0;
4123 if (GET_MODE (x
) != GET_MODE (y
))
4126 /* If we haven't done any renumbering, don't
4127 make any assumptions. */
4128 if (reg_renumber
== 0)
4129 return rtx_equal_p (x
, y
);
4133 reg_x
= REGNO (SUBREG_REG (x
));
4134 word_x
= SUBREG_WORD (x
);
4136 if (reg_renumber
[reg_x
] >= 0)
4138 reg_x
= reg_renumber
[reg_x
] + word_x
;
4146 if (reg_renumber
[reg_x
] >= 0)
4147 reg_x
= reg_renumber
[reg_x
];
4150 if (GET_CODE (y
) == SUBREG
)
4152 reg_y
= REGNO (SUBREG_REG (y
));
4153 word_y
= SUBREG_WORD (y
);
4155 if (reg_renumber
[reg_y
] >= 0)
4157 reg_y
= reg_renumber
[reg_y
];
4165 if (reg_renumber
[reg_y
] >= 0)
4166 reg_y
= reg_renumber
[reg_y
];
4169 return reg_x
>= 0 && reg_x
== reg_y
&& word_x
== word_y
;
4172 /* Now we have disposed of all the cases
4173 in which different rtx codes can match. */
4174 if (code
!= GET_CODE (y
))
4186 return INTVAL (x
) == INTVAL (y
);
4189 /* We can't assume nonlocal labels have their following insns yet. */
4190 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
4191 return XEXP (x
, 0) == XEXP (y
, 0);
4193 /* Two label-refs are equivalent if they point at labels
4194 in the same position in the instruction stream. */
4195 return (next_real_insn (XEXP (x
, 0))
4196 == next_real_insn (XEXP (y
, 0)));
4199 return XSTR (x
, 0) == XSTR (y
, 0);
4205 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4207 if (GET_MODE (x
) != GET_MODE (y
))
4210 /* For commutative operations, the RTX match if the operand match in any
4211 order. Also handle the simple binary and unary cases without a loop. */
4212 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4213 return ((rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
4214 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)))
4215 || (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 1))
4216 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 0))));
4217 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4218 return (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
4219 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)));
4220 else if (GET_RTX_CLASS (code
) == '1')
4221 return rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0));
4223 /* Compare the elements. If any pair of corresponding elements
4224 fail to match, return 0 for the whole things. */
4226 fmt
= GET_RTX_FORMAT (code
);
4227 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4233 if (XWINT (x
, i
) != XWINT (y
, i
))
4238 if (XINT (x
, i
) != XINT (y
, i
))
4243 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4248 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
4253 if (XEXP (x
, i
) != XEXP (y
, i
))
4260 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4262 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4263 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
4274 /* If X is a hard register or equivalent to one or a subregister of one,
4275 return the hard register number. If X is a pseudo register that was not
4276 assigned a hard register, return the pseudo register number. Otherwise,
4277 return -1. Any rtx is valid for X. */
4283 if (GET_CODE (x
) == REG
)
4285 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
4286 return reg_renumber
[REGNO (x
)];
4289 if (GET_CODE (x
) == SUBREG
)
4291 int base
= true_regnum (SUBREG_REG (x
));
4292 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
4293 return SUBREG_WORD (x
) + base
;
4298 /* Optimize code of the form:
4300 for (x = a[i]; x; ...)
4302 for (x = a[i]; x; ...)
4306 Loop optimize will change the above code into
4310 { ...; if (! (x = ...)) break; }
4313 { ...; if (! (x = ...)) break; }
4316 In general, if the first test fails, the program can branch
4317 directly to `foo' and skip the second try which is doomed to fail.
4318 We run this after loop optimization and before flow analysis. */
4320 /* When comparing the insn patterns, we track the fact that different
4321 pseudo-register numbers may have been used in each computation.
4322 The following array stores an equivalence -- same_regs[I] == J means
4323 that pseudo register I was used in the first set of tests in a context
4324 where J was used in the second set. We also count the number of such
4325 pending equivalences. If nonzero, the expressions really aren't the
4328 static int *same_regs
;
4330 static int num_same_regs
;
4332 /* Track any registers modified between the target of the first jump and
4333 the second jump. They never compare equal. */
4335 static char *modified_regs
;
4337 /* Record if memory was modified. */
4339 static int modified_mem
;
4341 /* Called via note_stores on each insn between the target of the first
4342 branch and the second branch. It marks any changed registers. */
4345 mark_modified_reg (dest
, x
)
4351 if (GET_CODE (dest
) == SUBREG
)
4352 dest
= SUBREG_REG (dest
);
4354 if (GET_CODE (dest
) == MEM
)
4357 if (GET_CODE (dest
) != REG
)
4360 regno
= REGNO (dest
);
4361 if (regno
>= FIRST_PSEUDO_REGISTER
)
4362 modified_regs
[regno
] = 1;
4364 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
4365 modified_regs
[regno
+ i
] = 1;
4368 /* F is the first insn in the chain of insns. */
4371 thread_jumps (f
, max_reg
, flag_before_loop
)
4374 int flag_before_loop
;
4376 /* Basic algorithm is to find a conditional branch,
4377 the label it may branch to, and the branch after
4378 that label. If the two branches test the same condition,
4379 walk back from both branch paths until the insn patterns
4380 differ, or code labels are hit. If we make it back to
4381 the target of the first branch, then we know that the first branch
4382 will either always succeed or always fail depending on the relative
4383 senses of the two branches. So adjust the first branch accordingly
4386 rtx label
, b1
, b2
, t1
, t2
;
4387 enum rtx_code code1
, code2
;
4388 rtx b1op0
, b1op1
, b2op0
, b2op1
;
4393 /* Allocate register tables and quick-reset table. */
4394 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
4395 same_regs
= (int *) alloca (max_reg
* sizeof (int));
4396 all_reset
= (int *) alloca (max_reg
* sizeof (int));
4397 for (i
= 0; i
< max_reg
; i
++)
4404 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
4406 /* Get to a candidate branch insn. */
4407 if (GET_CODE (b1
) != JUMP_INSN
4408 || ! condjump_p (b1
) || simplejump_p (b1
)
4409 || JUMP_LABEL (b1
) == 0)
4412 bzero (modified_regs
, max_reg
* sizeof (char));
4415 bcopy ((char *) all_reset
, (char *) same_regs
,
4416 max_reg
* sizeof (int));
4419 label
= JUMP_LABEL (b1
);
4421 /* Look for a branch after the target. Record any registers and
4422 memory modified between the target and the branch. Stop when we
4423 get to a label since we can't know what was changed there. */
4424 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
4426 if (GET_CODE (b2
) == CODE_LABEL
)
4429 else if (GET_CODE (b2
) == JUMP_INSN
)
4431 /* If this is an unconditional jump and is the only use of
4432 its target label, we can follow it. */
4433 if (simplejump_p (b2
)
4434 && JUMP_LABEL (b2
) != 0
4435 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
4437 b2
= JUMP_LABEL (b2
);
4444 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
4447 if (GET_CODE (b2
) == CALL_INSN
)
4450 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
4451 if (call_used_regs
[i
] && ! fixed_regs
[i
]
4452 && i
!= STACK_POINTER_REGNUM
4453 && i
!= FRAME_POINTER_REGNUM
4454 && i
!= HARD_FRAME_POINTER_REGNUM
4455 && i
!= ARG_POINTER_REGNUM
)
4456 modified_regs
[i
] = 1;
4459 note_stores (PATTERN (b2
), mark_modified_reg
);
4462 /* Check the next candidate branch insn from the label
4465 || GET_CODE (b2
) != JUMP_INSN
4467 || ! condjump_p (b2
)
4468 || simplejump_p (b2
))
4471 /* Get the comparison codes and operands, reversing the
4472 codes if appropriate. If we don't have comparison codes,
4473 we can't do anything. */
4474 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
4475 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
4476 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
4477 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
4478 code1
= reverse_condition (code1
);
4480 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
4481 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
4482 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
4483 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
4484 code2
= reverse_condition (code2
);
4486 /* If they test the same things and knowing that B1 branches
4487 tells us whether or not B2 branches, check if we
4488 can thread the branch. */
4489 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
4490 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
4491 && (comparison_dominates_p (code1
, code2
)
4492 || (comparison_dominates_p (code1
, reverse_condition (code2
))
4493 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1
)),
4497 t1
= prev_nonnote_insn (b1
);
4498 t2
= prev_nonnote_insn (b2
);
4500 while (t1
!= 0 && t2
!= 0)
4504 /* We have reached the target of the first branch.
4505 If there are no pending register equivalents,
4506 we know that this branch will either always
4507 succeed (if the senses of the two branches are
4508 the same) or always fail (if not). */
4511 if (num_same_regs
!= 0)
4514 if (comparison_dominates_p (code1
, code2
))
4515 new_label
= JUMP_LABEL (b2
);
4517 new_label
= get_label_after (b2
);
4519 if (JUMP_LABEL (b1
) != new_label
)
4521 rtx prev
= PREV_INSN (new_label
);
4523 if (flag_before_loop
4524 && NOTE_LINE_NUMBER (prev
) == NOTE_INSN_LOOP_BEG
)
4526 /* Don't thread to the loop label. If a loop
4527 label is reused, loop optimization will
4528 be disabled for that loop. */
4529 new_label
= gen_label_rtx ();
4530 emit_label_after (new_label
, PREV_INSN (prev
));
4532 changed
|= redirect_jump (b1
, new_label
);
4537 /* If either of these is not a normal insn (it might be
4538 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4539 have already been skipped above.) Similarly, fail
4540 if the insns are different. */
4541 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
4542 || recog_memoized (t1
) != recog_memoized (t2
)
4543 || ! rtx_equal_for_thread_p (PATTERN (t1
),
4547 t1
= prev_nonnote_insn (t1
);
4548 t2
= prev_nonnote_insn (t2
);
4555 /* This is like RTX_EQUAL_P except that it knows about our handling of
4556 possibly equivalent registers and knows to consider volatile and
4557 modified objects as not equal.
4559 YINSN is the insn containing Y. */
4562 rtx_equal_for_thread_p (x
, y
, yinsn
)
4568 register enum rtx_code code
;
4571 code
= GET_CODE (x
);
4572 /* Rtx's of different codes cannot be equal. */
4573 if (code
!= GET_CODE (y
))
4576 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4577 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4579 if (GET_MODE (x
) != GET_MODE (y
))
4582 /* For floating-point, consider everything unequal. This is a bit
4583 pessimistic, but this pass would only rarely do anything for FP
4585 if (TARGET_FLOAT_FORMAT
== IEEE_FLOAT_FORMAT
4586 && FLOAT_MODE_P (GET_MODE (x
)) && ! flag_fast_math
)
4589 /* For commutative operations, the RTX match if the operand match in any
4590 order. Also handle the simple binary and unary cases without a loop. */
4591 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4592 return ((rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4593 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
))
4594 || (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 1), yinsn
)
4595 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 0), yinsn
)));
4596 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4597 return (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4598 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
));
4599 else if (GET_RTX_CLASS (code
) == '1')
4600 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4602 /* Handle special-cases first. */
4606 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
4609 /* If neither is user variable or hard register, check for possible
4611 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
4612 || REGNO (x
) < FIRST_PSEUDO_REGISTER
4613 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
4616 if (same_regs
[REGNO (x
)] == -1)
4618 same_regs
[REGNO (x
)] = REGNO (y
);
4621 /* If this is the first time we are seeing a register on the `Y'
4622 side, see if it is the last use. If not, we can't thread the
4623 jump, so mark it as not equivalent. */
4624 if (REGNO_LAST_UID (REGNO (y
)) != INSN_UID (yinsn
))
4630 return (same_regs
[REGNO (x
)] == REGNO (y
));
4635 /* If memory modified or either volatile, not equivalent.
4636 Else, check address. */
4637 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4640 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4643 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4649 /* Cancel a pending `same_regs' if setting equivalenced registers.
4650 Then process source. */
4651 if (GET_CODE (SET_DEST (x
)) == REG
4652 && GET_CODE (SET_DEST (y
)) == REG
)
4654 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
4656 same_regs
[REGNO (SET_DEST (x
))] = -1;
4659 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
4663 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
4666 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
4669 return XEXP (x
, 0) == XEXP (y
, 0);
4672 return XSTR (x
, 0) == XSTR (y
, 0);
4681 fmt
= GET_RTX_FORMAT (code
);
4682 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4687 if (XWINT (x
, i
) != XWINT (y
, i
))
4693 if (XINT (x
, i
) != XINT (y
, i
))
4699 /* Two vectors must have the same length. */
4700 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4703 /* And the corresponding elements must match. */
4704 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4705 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
4706 XVECEXP (y
, i
, j
), yinsn
) == 0)
4711 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
4717 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4722 /* These are just backpointers, so they don't matter. */
4728 /* It is believed that rtx's at this level will never
4729 contain anything but integers and other rtx's,
4730 except for within LABEL_REFs and SYMBOL_REFs. */
4739 /* Return the insn that NEW can be safely inserted in front of starting at
4740 the jump insn INSN. Return 0 if it is not safe to do this jump
4741 optimization. Note that NEW must contain a single set. */
4744 find_insert_position (insn
, new)
4751 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
4752 if (GET_CODE (PATTERN (new)) != PARALLEL
)
4755 for (i
= XVECLEN (PATTERN (new), 0) - 1; i
>= 0; i
--)
4756 if (GET_CODE (XVECEXP (PATTERN (new), 0, i
)) == CLOBBER
4757 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
4764 /* There is a good chance that the previous insn PREV sets the thing
4765 being clobbered (often the CC in a hard reg). If PREV does not
4766 use what NEW sets, we can insert NEW before PREV. */
4768 prev
= prev_active_insn (insn
);
4769 for (i
= XVECLEN (PATTERN (new), 0) - 1; i
>= 0; i
--)
4770 if (GET_CODE (XVECEXP (PATTERN (new), 0, i
)) == CLOBBER
4771 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
4773 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
4777 return reg_mentioned_p (SET_DEST (single_set (new)), prev
) ? 0 : prev
;