1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91, 92, 1993 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This is the jump-optimization pass of the compiler.
22 It is run two or three times: once before cse, sometimes once after cse,
23 and once after reload (before final).
25 jump_optimize deletes unreachable code and labels that are not used.
26 It also deletes jumps that jump to the following insn,
27 and simplifies jumps around unconditional jumps and jumps
28 to unconditional jumps.
30 Each CODE_LABEL has a count of the times it is used
31 stored in the LABEL_NUSES internal field, and each JUMP_INSN
32 has one label that it refers to stored in the
33 JUMP_LABEL internal field. With this we can detect labels that
34 become unused because of the deletion of all the jumps that
35 formerly used them. The JUMP_LABEL info is sometimes looked
38 Optionally, cross-jumping can be done. Currently it is done
39 only the last time (when after reload and before final).
40 In fact, the code for cross-jumping now assumes that register
41 allocation has been done, since it uses `rtx_renumbered_equal_p'.
43 Jump optimization is done after cse when cse's constant-propagation
44 causes jumps to become unconditional or to be deleted.
46 Unreachable loops are not detected here, because the labels
47 have references and the insns appear reachable from the labels.
48 find_basic_blocks in flow.c finds and deletes such loops.
50 The subroutines delete_insn, redirect_jump, and invert_jump are used
51 from other passes as well. */
56 #include "hard-reg-set.h"
59 #include "insn-config.h"
60 #include "insn-flags.h"
63 /* ??? Eventually must record somehow the labels used by jumps
64 from nested functions. */
65 /* Pre-record the next or previous real insn for each label?
66 No, this pass is very fast anyway. */
67 /* Condense consecutive labels?
68 This would make life analysis faster, maybe. */
69 /* Optimize jump y; x: ... y: jumpif... x?
70 Don't know if it is worth bothering with. */
71 /* Optimize two cases of conditional jump to conditional jump?
72 This can never delete any instruction or make anything dead,
73 or even change what is live at any point.
74 So perhaps let combiner do it. */
76 /* Vector indexed by uid.
77 For each CODE_LABEL, index by its uid to get first unconditional jump
78 that jumps to the label.
79 For each JUMP_INSN, index by its uid to get the next unconditional jump
80 that jumps to the same label.
81 Element 0 is the start of a chain of all return insns.
82 (It is safe to use element 0 because insn uid 0 is not used. */
84 static rtx
*jump_chain
;
86 /* List of labels referred to from initializers.
87 These can never be deleted. */
90 /* Maximum index in jump_chain. */
92 static int max_jump_chain
;
94 /* Set nonzero by jump_optimize if control can fall through
95 to the end of the function. */
98 /* Indicates whether death notes are significant in cross jump analysis.
99 Normally they are not significant, because of A and B jump to C,
100 and R dies in A, it must die in B. But this might not be true after
101 stack register conversion, and we must compare death notes in that
104 static int cross_jump_death_matters
= 0;
106 static int duplicate_loop_exit_test ();
107 void redirect_tablejump ();
108 static int delete_labelref_insn ();
109 static void mark_jump_label ();
111 void delete_computation ();
112 static void delete_from_jump_chain ();
113 static int tension_vector_labels ();
114 static void find_cross_jump ();
115 static void do_cross_jump ();
116 static int jump_back_p ();
118 extern rtx
gen_jump ();
120 /* Delete no-op jumps and optimize jumps to jumps
121 and jumps around jumps.
122 Delete unused labels and unreachable code.
124 If CROSS_JUMP is 1, detect matching code
125 before a jump and its destination and unify them.
126 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
128 If NOOP_MOVES is nonzero, delete no-op move insns.
130 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
131 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
133 If `optimize' is zero, don't change any code,
134 just determine whether control drops off the end of the function.
135 This case occurs when we have -W and not -O.
136 It works because `delete_insn' checks the value of `optimize'
137 and refrains from actually deleting when that is 0. */
140 jump_optimize (f
, cross_jump
, noop_moves
, after_regscan
)
146 register rtx insn
, next
;
152 cross_jump_death_matters
= (cross_jump
== 2);
154 /* Initialize LABEL_NUSES and JUMP_LABEL fields. */
156 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
158 if (GET_CODE (insn
) == CODE_LABEL
)
159 LABEL_NUSES (insn
) = (LABEL_PRESERVE_P (insn
) != 0);
160 else if (GET_CODE (insn
) == JUMP_INSN
)
161 JUMP_LABEL (insn
) = 0;
162 if (INSN_UID (insn
) > max_uid
)
163 max_uid
= INSN_UID (insn
);
168 /* Delete insns following barriers, up to next label. */
170 for (insn
= f
; insn
;)
172 if (GET_CODE (insn
) == BARRIER
)
174 insn
= NEXT_INSN (insn
);
175 while (insn
!= 0 && GET_CODE (insn
) != CODE_LABEL
)
177 if (GET_CODE (insn
) == NOTE
178 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
179 insn
= NEXT_INSN (insn
);
181 insn
= delete_insn (insn
);
183 /* INSN is now the code_label. */
186 insn
= NEXT_INSN (insn
);
189 /* Leave some extra room for labels and duplicate exit test insns
191 max_jump_chain
= max_uid
* 14 / 10;
192 jump_chain
= (rtx
*) alloca (max_jump_chain
* sizeof (rtx
));
193 bzero (jump_chain
, max_jump_chain
* sizeof (rtx
));
195 /* Mark the label each jump jumps to.
196 Combine consecutive labels, and count uses of labels.
198 For each label, make a chain (using `jump_chain')
199 of all the *unconditional* jumps that jump to it;
200 also make a chain of all returns. */
202 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
203 if ((GET_CODE (insn
) == JUMP_INSN
|| GET_CODE (insn
) == INSN
204 || GET_CODE (insn
) == CALL_INSN
)
205 && ! INSN_DELETED_P (insn
))
207 mark_jump_label (PATTERN (insn
), insn
, cross_jump
);
208 if (GET_CODE (insn
) == JUMP_INSN
)
210 if (JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
212 jump_chain
[INSN_UID (insn
)]
213 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
214 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
216 if (GET_CODE (PATTERN (insn
)) == RETURN
)
218 jump_chain
[INSN_UID (insn
)] = jump_chain
[0];
219 jump_chain
[0] = insn
;
224 /* Keep track of labels used from static data;
225 they cannot ever be deleted. */
227 for (insn
= forced_labels
; insn
; insn
= XEXP (insn
, 1))
228 LABEL_NUSES (XEXP (insn
, 0))++;
230 /* Delete all labels already not referenced.
231 Also find the last insn. */
234 for (insn
= f
; insn
; )
236 if (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NUSES (insn
) == 0)
237 insn
= delete_insn (insn
);
241 insn
= NEXT_INSN (insn
);
247 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
248 If so record that this function can drop off the end. */
254 /* One label can follow the end-note: the return label. */
255 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
256 /* Ordinary insns can follow it if returning a structure. */
257 || GET_CODE (insn
) == INSN
258 /* If machine uses explicit RETURN insns, no epilogue,
259 then one of them follows the note. */
260 || (GET_CODE (insn
) == JUMP_INSN
261 && GET_CODE (PATTERN (insn
)) == RETURN
)
262 /* Other kinds of notes can follow also. */
263 || (GET_CODE (insn
) == NOTE
264 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
265 insn
= PREV_INSN (insn
);
268 /* Report if control can fall through at the end of the function. */
269 if (insn
&& GET_CODE (insn
) == NOTE
270 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
271 && ! INSN_DELETED_P (insn
))
274 /* Zero the "deleted" flag of all the "deleted" insns. */
275 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
276 INSN_DELETED_P (insn
) = 0;
283 /* If we fall through to the epilogue, see if we can insert a RETURN insn
284 in front of it. If the machine allows it at this point (we might be
285 after reload for a leaf routine), it will improve optimization for it
287 insn
= get_last_insn ();
288 while (insn
&& GET_CODE (insn
) == NOTE
)
289 insn
= PREV_INSN (insn
);
291 if (insn
&& GET_CODE (insn
) != BARRIER
)
293 emit_jump_insn (gen_return ());
300 for (insn
= f
; insn
; )
302 next
= NEXT_INSN (insn
);
304 if (GET_CODE (insn
) == INSN
)
306 register rtx body
= PATTERN (insn
);
308 /* Combine stack_adjusts with following push_insns. */
310 if (GET_CODE (body
) == SET
311 && SET_DEST (body
) == stack_pointer_rtx
312 && GET_CODE (SET_SRC (body
)) == PLUS
313 && XEXP (SET_SRC (body
), 0) == stack_pointer_rtx
314 && GET_CODE (XEXP (SET_SRC (body
), 1)) == CONST_INT
315 && INTVAL (XEXP (SET_SRC (body
), 1)) > 0)
318 rtx stack_adjust_insn
= insn
;
319 int stack_adjust_amount
= INTVAL (XEXP (SET_SRC (body
), 1));
320 int total_pushed
= 0;
323 /* Find all successive push insns. */
325 /* Don't convert more than three pushes;
326 that starts adding too many displaced addresses
327 and the whole thing starts becoming a losing
332 p
= next_nonnote_insn (p
);
333 if (p
== 0 || GET_CODE (p
) != INSN
)
336 if (GET_CODE (pbody
) != SET
)
338 dest
= SET_DEST (pbody
);
339 /* Allow a no-op move between the adjust and the push. */
340 if (GET_CODE (dest
) == REG
341 && GET_CODE (SET_SRC (pbody
)) == REG
342 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
344 if (! (GET_CODE (dest
) == MEM
345 && GET_CODE (XEXP (dest
, 0)) == POST_INC
346 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
349 if (total_pushed
+ GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)))
350 > stack_adjust_amount
)
352 total_pushed
+= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
355 /* Discard the amount pushed from the stack adjust;
356 maybe eliminate it entirely. */
357 if (total_pushed
>= stack_adjust_amount
)
359 delete_insn (stack_adjust_insn
);
360 total_pushed
= stack_adjust_amount
;
363 XEXP (SET_SRC (PATTERN (stack_adjust_insn
)), 1)
364 = GEN_INT (stack_adjust_amount
- total_pushed
);
366 /* Change the appropriate push insns to ordinary stores. */
368 while (total_pushed
> 0)
371 p
= next_nonnote_insn (p
);
372 if (GET_CODE (p
) != INSN
)
375 if (GET_CODE (pbody
) == SET
)
377 dest
= SET_DEST (pbody
);
378 if (! (GET_CODE (dest
) == MEM
379 && GET_CODE (XEXP (dest
, 0)) == POST_INC
380 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
382 total_pushed
-= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
383 /* If this push doesn't fully fit in the space
384 of the stack adjust that we deleted,
385 make another stack adjust here for what we
386 didn't use up. There should be peepholes
387 to recognize the resulting sequence of insns. */
388 if (total_pushed
< 0)
390 emit_insn_before (gen_add2_insn (stack_pointer_rtx
,
391 GEN_INT (- total_pushed
)),
396 = plus_constant (stack_pointer_rtx
, total_pushed
);
401 /* Detect and delete no-op move instructions
402 resulting from not allocating a parameter in a register. */
404 if (GET_CODE (body
) == SET
405 && (SET_DEST (body
) == SET_SRC (body
)
406 || (GET_CODE (SET_DEST (body
)) == MEM
407 && GET_CODE (SET_SRC (body
)) == MEM
408 && rtx_equal_p (SET_SRC (body
), SET_DEST (body
))))
409 && ! (GET_CODE (SET_DEST (body
)) == MEM
410 && MEM_VOLATILE_P (SET_DEST (body
)))
411 && ! (GET_CODE (SET_SRC (body
)) == MEM
412 && MEM_VOLATILE_P (SET_SRC (body
))))
415 /* Detect and ignore no-op move instructions
416 resulting from smart or fortuitous register allocation. */
418 else if (GET_CODE (body
) == SET
)
420 int sreg
= true_regnum (SET_SRC (body
));
421 int dreg
= true_regnum (SET_DEST (body
));
423 if (sreg
== dreg
&& sreg
>= 0)
425 else if (sreg
>= 0 && dreg
>= 0)
428 rtx tem
= find_equiv_reg (NULL_RTX
, insn
, 0,
429 sreg
, NULL_PTR
, dreg
,
430 GET_MODE (SET_SRC (body
)));
432 #ifdef PRESERVE_DEATH_INFO_REGNO_P
433 /* Deleting insn could lose a death-note for SREG or DREG
434 so don't do it if final needs accurate death-notes. */
435 if (! PRESERVE_DEATH_INFO_REGNO_P (sreg
)
436 && ! PRESERVE_DEATH_INFO_REGNO_P (dreg
))
439 /* DREG may have been the target of a REG_DEAD note in
440 the insn which makes INSN redundant. If so, reorg
441 would still think it is dead. So search for such a
442 note and delete it if we find it. */
443 for (trial
= prev_nonnote_insn (insn
);
444 trial
&& GET_CODE (trial
) != CODE_LABEL
;
445 trial
= prev_nonnote_insn (trial
))
446 if (find_regno_note (trial
, REG_DEAD
, dreg
))
448 remove_death (dreg
, trial
);
453 && GET_MODE (tem
) == GET_MODE (SET_DEST (body
)))
457 else if (dreg
>= 0 && CONSTANT_P (SET_SRC (body
))
458 && find_equiv_reg (SET_SRC (body
), insn
, 0, dreg
,
460 GET_MODE (SET_DEST (body
))))
462 /* This handles the case where we have two consecutive
463 assignments of the same constant to pseudos that didn't
464 get a hard reg. Each SET from the constant will be
465 converted into a SET of the spill register and an
466 output reload will be made following it. This produces
467 two loads of the same constant into the same spill
472 /* Look back for a death note for the first reg.
473 If there is one, it is no longer accurate. */
474 while (in_insn
&& GET_CODE (in_insn
) != CODE_LABEL
)
476 if ((GET_CODE (in_insn
) == INSN
477 || GET_CODE (in_insn
) == JUMP_INSN
)
478 && find_regno_note (in_insn
, REG_DEAD
, dreg
))
480 remove_death (dreg
, in_insn
);
483 in_insn
= PREV_INSN (in_insn
);
486 /* Delete the second load of the value. */
490 else if (GET_CODE (body
) == PARALLEL
)
492 /* If each part is a set between two identical registers or
493 a USE or CLOBBER, delete the insn. */
497 for (i
= XVECLEN (body
, 0) - 1; i
>= 0; i
--)
499 tem
= XVECEXP (body
, 0, i
);
500 if (GET_CODE (tem
) == USE
|| GET_CODE (tem
) == CLOBBER
)
503 if (GET_CODE (tem
) != SET
504 || (sreg
= true_regnum (SET_SRC (tem
))) < 0
505 || (dreg
= true_regnum (SET_DEST (tem
))) < 0
513 #if !BYTES_BIG_ENDIAN /* Not worth the hair to detect this
514 in the big-endian case. */
515 /* Also delete insns to store bit fields if they are no-ops. */
516 else if (GET_CODE (body
) == SET
517 && GET_CODE (SET_DEST (body
)) == ZERO_EXTRACT
518 && XEXP (SET_DEST (body
), 2) == const0_rtx
519 && XEXP (SET_DEST (body
), 0) == SET_SRC (body
)
520 && ! (GET_CODE (SET_SRC (body
)) == MEM
521 && MEM_VOLATILE_P (SET_SRC (body
))))
523 #endif /* not BYTES_BIG_ENDIAN */
528 /* If we haven't yet gotten to reload and we have just run regscan,
529 delete any insn that sets a register that isn't used elsewhere.
530 This helps some of the optimizations below by having less insns
531 being jumped around. */
533 if (! reload_completed
&& after_regscan
)
534 for (insn
= f
; insn
; insn
= next
)
536 rtx set
= single_set (insn
);
538 next
= NEXT_INSN (insn
);
540 if (set
&& GET_CODE (SET_DEST (set
)) == REG
541 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
542 && regno_first_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
)
543 && regno_last_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
)
544 && ! side_effects_p (SET_SRC (set
)))
548 /* Now iterate optimizing jumps until nothing changes over one pass. */
554 for (insn
= f
; insn
; insn
= next
)
557 rtx temp
, temp1
, temp2
, temp3
, temp4
, temp5
, temp6
;
559 int this_is_simplejump
, this_is_condjump
, reversep
;
561 /* If NOT the first iteration, if this is the last jump pass
562 (just before final), do the special peephole optimizations.
563 Avoiding the first iteration gives ordinary jump opts
564 a chance to work before peephole opts. */
566 if (reload_completed
&& !first
&& !flag_no_peephole
)
567 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
571 /* That could have deleted some insns after INSN, so check now
572 what the following insn is. */
574 next
= NEXT_INSN (insn
);
576 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
577 jump. Try to optimize by duplicating the loop exit test if so.
578 This is only safe immediately after regscan, because it uses
579 the values of regno_first_uid and regno_last_uid. */
580 if (after_regscan
&& GET_CODE (insn
) == NOTE
581 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
582 && (temp1
= next_nonnote_insn (insn
)) != 0
583 && simplejump_p (temp1
))
585 temp
= PREV_INSN (insn
);
586 if (duplicate_loop_exit_test (insn
))
589 next
= NEXT_INSN (temp
);
594 if (GET_CODE (insn
) != JUMP_INSN
)
597 this_is_simplejump
= simplejump_p (insn
);
598 this_is_condjump
= condjump_p (insn
);
600 /* Tension the labels in dispatch tables. */
602 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
603 changed
|= tension_vector_labels (PATTERN (insn
), 0);
604 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
605 changed
|= tension_vector_labels (PATTERN (insn
), 1);
607 /* If a dispatch table always goes to the same place,
608 get rid of it and replace the insn that uses it. */
610 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
611 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
614 rtx pat
= PATTERN (insn
);
615 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
616 int len
= XVECLEN (pat
, diff_vec_p
);
617 rtx dispatch
= prev_real_insn (insn
);
619 for (i
= 0; i
< len
; i
++)
620 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
621 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
625 && GET_CODE (dispatch
) == JUMP_INSN
626 && JUMP_LABEL (dispatch
) != 0
627 /* Don't mess with a casesi insn. */
628 && !(GET_CODE (PATTERN (dispatch
)) == SET
629 && (GET_CODE (SET_SRC (PATTERN (dispatch
)))
631 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
633 redirect_tablejump (dispatch
,
634 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
639 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
641 /* If a jump references the end of the function, try to turn
642 it into a RETURN insn, possibly a conditional one. */
643 if (JUMP_LABEL (insn
)
644 && (next_active_insn (JUMP_LABEL (insn
)) == 0
645 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn
))))
647 changed
|= redirect_jump (insn
, NULL_RTX
);
649 /* Detect jump to following insn. */
650 if (reallabelprev
== insn
&& condjump_p (insn
))
657 /* If we have an unconditional jump preceded by a USE, try to put
658 the USE before the target and jump there. This simplifies many
659 of the optimizations below since we don't have to worry about
660 dealing with these USE insns. We only do this if the label
661 being branch to already has the identical USE or if code
662 never falls through to that label. */
664 if (this_is_simplejump
665 && (temp
= prev_nonnote_insn (insn
)) != 0
666 && GET_CODE (temp
) == INSN
&& GET_CODE (PATTERN (temp
)) == USE
667 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
668 && (GET_CODE (temp1
) == BARRIER
669 || (GET_CODE (temp1
) == INSN
670 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
)))))
672 if (GET_CODE (temp1
) == BARRIER
)
674 emit_insn_after (PATTERN (temp
), temp1
);
675 temp1
= NEXT_INSN (temp1
);
679 redirect_jump (insn
, get_label_before (temp1
));
680 reallabelprev
= prev_real_insn (temp1
);
684 /* Simplify if (...) x = a; else x = b; by converting it
685 to x = b; if (...) x = a;
686 if B is sufficiently simple, the test doesn't involve X,
687 and nothing in the test modifies B or X.
689 If we have small register classes, we also can't do this if X
692 If the "x = b;" insn has any REG_NOTES, we don't do this because
693 of the possibility that we are running after CSE and there is a
694 REG_EQUAL note that is only valid if the branch has already been
695 taken. If we move the insn with the REG_EQUAL note, we may
696 fold the comparison to always be false in a later CSE pass.
697 (We could also delete the REG_NOTES when moving the insn, but it
698 seems simpler to not move it.) An exception is that we can move
699 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
700 value is the same as "b".
702 INSN is the branch over the `else' part.
706 TEMP to the jump insn preceding "x = a;"
708 TEMP2 to the insn that sets "x = b;"
709 TEMP3 to the insn that sets "x = a;"
710 TEMP4 to the set of "x = b"; */
712 if (this_is_simplejump
713 && (temp3
= prev_active_insn (insn
)) != 0
714 && GET_CODE (temp3
) == INSN
715 && (temp4
= single_set (temp3
)) != 0
716 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
717 #ifdef SMALL_REGISTER_CLASSES
718 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
720 && (temp2
= next_active_insn (insn
)) != 0
721 && GET_CODE (temp2
) == INSN
722 && (temp4
= single_set (temp2
)) != 0
723 && rtx_equal_p (SET_DEST (temp4
), temp1
)
724 && (GET_CODE (SET_SRC (temp4
)) == REG
725 || GET_CODE (SET_SRC (temp4
)) == SUBREG
726 || CONSTANT_P (SET_SRC (temp4
)))
727 && (REG_NOTES (temp2
) == 0
728 || ((REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUAL
729 || REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUIV
)
730 && XEXP (REG_NOTES (temp2
), 1) == 0
731 && rtx_equal_p (XEXP (REG_NOTES (temp2
), 0),
733 && (temp
= prev_active_insn (temp3
)) != 0
734 && condjump_p (temp
) && ! simplejump_p (temp
)
735 /* TEMP must skip over the "x = a;" insn */
736 && prev_real_insn (JUMP_LABEL (temp
)) == insn
737 && no_labels_between_p (insn
, JUMP_LABEL (temp
))
738 /* There must be no other entries to the "x = b;" insn. */
739 && no_labels_between_p (JUMP_LABEL (temp
), temp2
)
740 /* INSN must either branch to the insn after TEMP2 or the insn
741 after TEMP2 must branch to the same place as INSN. */
742 && (reallabelprev
== temp2
743 || ((temp5
= next_active_insn (temp2
)) != 0
744 && simplejump_p (temp5
)
745 && JUMP_LABEL (temp5
) == JUMP_LABEL (insn
))))
747 /* The test expression, X, may be a complicated test with
748 multiple branches. See if we can find all the uses of
749 the label that TEMP branches to without hitting a CALL_INSN
750 or a jump to somewhere else. */
751 rtx target
= JUMP_LABEL (temp
);
752 int nuses
= LABEL_NUSES (target
);
755 /* Set P to the first jump insn that goes around "x = a;". */
756 for (p
= temp
; nuses
&& p
; p
= prev_nonnote_insn (p
))
758 if (GET_CODE (p
) == JUMP_INSN
)
760 if (condjump_p (p
) && ! simplejump_p (p
)
761 && JUMP_LABEL (p
) == target
)
770 else if (GET_CODE (p
) == CALL_INSN
)
775 /* We cannot insert anything between a set of cc and its use
776 so if P uses cc0, we must back up to the previous insn. */
777 q
= prev_nonnote_insn (p
);
778 if (q
&& GET_RTX_CLASS (GET_CODE (q
)) == 'i'
779 && sets_cc0_p (PATTERN (q
)))
786 /* If we found all the uses and there was no data conflict, we
787 can move the assignment unless we can branch into the middle
790 && no_labels_between_p (p
, insn
)
791 && ! reg_referenced_between_p (temp1
, p
, NEXT_INSN (temp3
))
792 && ! reg_set_between_p (temp1
, p
, temp3
)
793 && (GET_CODE (SET_SRC (temp4
)) == CONST_INT
794 || ! reg_set_between_p (SET_SRC (temp4
), p
, temp2
)))
796 emit_insn_after_with_line_notes (PATTERN (temp2
), p
, temp2
);
799 /* Set NEXT to an insn that we know won't go away. */
800 next
= next_active_insn (insn
);
802 /* Delete the jump around the set. Note that we must do
803 this before we redirect the test jumps so that it won't
804 delete the code immediately following the assignment
805 we moved (which might be a jump). */
809 /* We either have two consecutive labels or a jump to
810 a jump, so adjust all the JUMP_INSNs to branch to where
812 for (p
= NEXT_INSN (p
); p
!= next
; p
= NEXT_INSN (p
))
813 if (GET_CODE (p
) == JUMP_INSN
)
814 redirect_jump (p
, target
);
822 /* If we have if (...) x = exp; and branches are expensive,
823 EXP is a single insn, does not have any side effects, cannot
824 trap, and is not too costly, convert this to
825 t = exp; if (...) x = t;
827 Don't do this when we have CC0 because it is unlikely to help
828 and we'd need to worry about where to place the new insn and
829 the potential for conflicts. We also can't do this when we have
830 notes on the insn for the same reason as above.
834 TEMP to the "x = exp;" insn.
835 TEMP1 to the single set in the "x = exp; insn.
838 if (! reload_completed
839 && this_is_condjump
&& ! this_is_simplejump
841 && (temp
= next_nonnote_insn (insn
)) != 0
842 && GET_CODE (temp
) == INSN
843 && REG_NOTES (temp
) == 0
844 && (reallabelprev
== temp
845 || ((temp2
= next_active_insn (temp
)) != 0
846 && simplejump_p (temp2
)
847 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
848 && (temp1
= single_set (temp
)) != 0
849 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
850 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
851 #ifdef SMALL_REGISTER_CLASSES
852 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
854 && GET_CODE (SET_SRC (temp1
)) != REG
855 && GET_CODE (SET_SRC (temp1
)) != SUBREG
856 && GET_CODE (SET_SRC (temp1
)) != CONST_INT
857 && ! side_effects_p (SET_SRC (temp1
))
858 && ! may_trap_p (SET_SRC (temp1
))
859 && rtx_cost (SET_SRC (temp1
)) < 10)
861 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
863 if (validate_change (temp
, &SET_DEST (temp1
), new, 0))
865 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
866 emit_insn_after_with_line_notes (PATTERN (temp
),
867 PREV_INSN (insn
), temp
);
872 /* Similarly, if it takes two insns to compute EXP but they
873 have the same destination. Here TEMP3 will be the second
874 insn and TEMP4 the SET from that insn. */
876 if (! reload_completed
877 && this_is_condjump
&& ! this_is_simplejump
879 && (temp
= next_nonnote_insn (insn
)) != 0
880 && GET_CODE (temp
) == INSN
881 && REG_NOTES (temp
) == 0
882 && (temp3
= next_nonnote_insn (temp
)) != 0
883 && GET_CODE (temp3
) == INSN
884 && REG_NOTES (temp3
) == 0
885 && (reallabelprev
== temp3
886 || ((temp2
= next_active_insn (temp3
)) != 0
887 && simplejump_p (temp2
)
888 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
889 && (temp1
= single_set (temp
)) != 0
890 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
891 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
892 #ifdef SMALL_REGISTER_CLASSES
893 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
895 && ! side_effects_p (SET_SRC (temp1
))
896 && ! may_trap_p (SET_SRC (temp1
))
897 && rtx_cost (SET_SRC (temp1
)) < 10
898 && (temp4
= single_set (temp3
)) != 0
899 && rtx_equal_p (SET_DEST (temp4
), temp2
)
900 && ! side_effects_p (SET_SRC (temp4
))
901 && ! may_trap_p (SET_SRC (temp4
))
902 && rtx_cost (SET_SRC (temp4
)) < 10)
904 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
906 if (validate_change (temp
, &SET_DEST (temp1
), new, 0))
908 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
909 emit_insn_after_with_line_notes (PATTERN (temp
),
910 PREV_INSN (insn
), temp
);
911 emit_insn_after_with_line_notes
912 (replace_rtx (PATTERN (temp3
), temp2
, new),
913 PREV_INSN (insn
), temp3
);
919 /* Finally, handle the case where two insns are used to
920 compute EXP but a temporary register is used. Here we must
921 ensure that the temporary register is not used anywhere else. */
923 if (! reload_completed
925 && this_is_condjump
&& ! this_is_simplejump
927 && (temp
= next_nonnote_insn (insn
)) != 0
928 && GET_CODE (temp
) == INSN
929 && REG_NOTES (temp
) == 0
930 && (temp3
= next_nonnote_insn (temp
)) != 0
931 && GET_CODE (temp3
) == INSN
932 && REG_NOTES (temp3
) == 0
933 && (reallabelprev
== temp3
934 || ((temp2
= next_active_insn (temp3
)) != 0
935 && simplejump_p (temp2
)
936 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
937 && (temp1
= single_set (temp
)) != 0
938 && (temp5
= SET_DEST (temp1
), GET_CODE (temp5
) == REG
)
939 && REGNO (temp5
) >= FIRST_PSEUDO_REGISTER
940 && regno_first_uid
[REGNO (temp5
)] == INSN_UID (temp
)
941 && regno_last_uid
[REGNO (temp5
)] == INSN_UID (temp3
)
942 && ! side_effects_p (SET_SRC (temp1
))
943 && ! may_trap_p (SET_SRC (temp1
))
944 && rtx_cost (SET_SRC (temp1
)) < 10
945 && (temp4
= single_set (temp3
)) != 0
946 && (temp2
= SET_DEST (temp4
), GET_CODE (temp2
) == REG
)
947 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
948 #ifdef SMALL_REGISTER_CLASSES
949 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
951 && rtx_equal_p (SET_DEST (temp4
), temp2
)
952 && ! side_effects_p (SET_SRC (temp4
))
953 && ! may_trap_p (SET_SRC (temp4
))
954 && rtx_cost (SET_SRC (temp4
)) < 10)
956 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
958 if (validate_change (temp3
, &SET_DEST (temp4
), new, 0))
960 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
961 emit_insn_after_with_line_notes (PATTERN (temp
),
962 PREV_INSN (insn
), temp
);
963 emit_insn_after_with_line_notes (PATTERN (temp3
),
964 PREV_INSN (insn
), temp3
);
969 #endif /* HAVE_cc0 */
971 /* We deal with four cases:
973 1) x = a; if (...) x = b; and either A or B is zero,
974 2) if (...) x = 0; and jumps are expensive,
975 3) x = a; if (...) x = b; and A and B are constants where all the
976 set bits in A are also set in B and jumps are expensive, and
977 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
979 5) if (...) x = b; if jumps are even more expensive.
981 In each of these try to use a store-flag insn to avoid the jump.
982 (If the jump would be faster, the machine should not have
983 defined the scc insns!). These cases are often made by the
984 previous optimization.
986 INSN here is the jump around the store. We set:
988 TEMP to the "x = b;" insn.
990 TEMP2 to B (const0_rtx in the second case).
991 TEMP3 to A (X in the second case).
992 TEMP4 to the condition being tested.
993 TEMP5 to the earliest insn used to find the condition. */
995 if (/* We can't do this after reload has completed. */
997 && this_is_condjump
&& ! this_is_simplejump
998 /* Set TEMP to the "x = b;" insn. */
999 && (temp
= next_nonnote_insn (insn
)) != 0
1000 && GET_CODE (temp
) == INSN
1001 && GET_CODE (PATTERN (temp
)) == SET
1002 && GET_CODE (temp1
= SET_DEST (PATTERN (temp
))) == REG
1003 #ifdef SMALL_REGISTER_CLASSES
1004 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
1006 && GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
1007 && (GET_CODE (temp2
= SET_SRC (PATTERN (temp
))) == REG
1008 || GET_CODE (temp2
) == SUBREG
1009 || GET_CODE (temp2
) == CONST_INT
)
1010 /* Allow either form, but prefer the former if both apply.
1011 There is no point in using the old value of TEMP1 if
1012 it is a register, since cse will alias them. It can
1013 lose if the old value were a hard register since CSE
1014 won't replace hard registers. */
1015 && (((temp3
= reg_set_last (temp1
, insn
)) != 0
1016 && GET_CODE (temp3
) == CONST_INT
)
1017 /* Make the latter case look like x = x; if (...) x = 0; */
1020 && temp2
== const0_rtx
)
1021 #ifdef HAVE_conditional_move
1024 || BRANCH_COST
>= 3)))
1025 /* INSN must either branch to the insn after TEMP or the insn
1026 after TEMP must branch to the same place as INSN. */
1027 && (reallabelprev
== temp
1028 || ((temp4
= next_active_insn (temp
)) != 0
1029 && simplejump_p (temp4
)
1030 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
1031 && (temp4
= get_condition (insn
, &temp5
)) != 0
1032 /* We must be comparing objects whose modes imply the size.
1033 We could handle BLKmode if (1) emit_store_flag could
1034 and (2) we could find the size reliably. */
1035 && GET_MODE (XEXP (temp4
, 0)) != BLKmode
1037 /* If B is zero, OK; if A is zero, can only do (1) if we
1038 can reverse the condition. See if (3) applies possibly
1039 by reversing the condition. Prefer reversing to (4) when
1040 branches are very expensive. */
1041 && ((reversep
= 0, temp2
== const0_rtx
)
1042 || (temp3
== const0_rtx
1043 && (reversep
= can_reverse_comparison_p (temp4
, insn
)))
1044 || (BRANCH_COST
>= 2
1045 && GET_CODE (temp2
) == CONST_INT
1046 && GET_CODE (temp3
) == CONST_INT
1047 && ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp2
)
1048 || ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp3
)
1049 && (reversep
= can_reverse_comparison_p (temp4
,
1051 #ifdef HAVE_conditional_move
1054 || BRANCH_COST
>= 3)
1056 /* If the previous insn sets CC0 and something else, we can't
1057 do this since we are going to delete that insn. */
1059 && ! ((temp6
= prev_nonnote_insn (insn
)) != 0
1060 && GET_CODE (temp6
) == INSN
1061 && (sets_cc0_p (PATTERN (temp6
)) == -1
1062 || (sets_cc0_p (PATTERN (temp6
)) == 1
1063 && FIND_REG_INC_NOTE (temp6
, NULL_RTX
))))
1067 enum rtx_code code
= GET_CODE (temp4
);
1068 rtx uval
, cval
, var
= temp1
;
1072 /* If necessary, reverse the condition. */
1074 code
= reverse_condition (code
), uval
= temp2
, cval
= temp3
;
1076 uval
= temp3
, cval
= temp2
;
1078 /* See if we can do this with a store-flag insn. */
1081 /* If CVAL is non-zero, normalize to -1. Otherwise,
1082 if UVAL is the constant 1, it is best to just compute
1083 the result directly. If UVAL is constant and STORE_FLAG_VALUE
1084 includes all of its bits, it is best to compute the flag
1085 value unnormalized and `and' it with UVAL. Otherwise,
1086 normalize to -1 and `and' with UVAL. */
1087 normalizep
= (cval
!= const0_rtx
? -1
1088 : (uval
== const1_rtx
? 1
1089 : (GET_CODE (uval
) == CONST_INT
1090 && (INTVAL (uval
) & ~STORE_FLAG_VALUE
) == 0)
1093 /* We will be putting the store-flag insn immediately in
1094 front of the comparison that was originally being done,
1095 so we know all the variables in TEMP4 will be valid.
1096 However, this might be in front of the assignment of
1097 A to VAR. If it is, it would clobber the store-flag
1098 we will be emitting.
1100 Therefore, emit into a temporary which will be copied to
1101 VAR immediately after TEMP. */
1103 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
1104 XEXP (temp4
, 0), XEXP (temp4
, 1),
1106 (code
== LTU
|| code
== LEU
1107 || code
== GEU
|| code
== GTU
),
1114 /* Put the store-flag insns in front of the first insn
1115 used to compute the condition to ensure that we
1116 use the same values of them as the current
1117 comparison. However, the remainder of the insns we
1118 generate will be placed directly in front of the
1119 jump insn, in case any of the pseudos we use
1120 are modified earlier. */
1125 emit_insns_before (seq
, temp5
);
1129 /* Both CVAL and UVAL are non-zero. */
1130 if (cval
!= const0_rtx
&& uval
!= const0_rtx
)
1134 tem1
= expand_and (uval
, target
, NULL_RTX
);
1135 if (GET_CODE (cval
) == CONST_INT
1136 && GET_CODE (uval
) == CONST_INT
1137 && (INTVAL (cval
) & INTVAL (uval
)) == INTVAL (cval
))
1141 tem2
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1142 target
, NULL_RTX
, 0);
1143 tem2
= expand_and (cval
, tem2
,
1144 (GET_CODE (tem2
) == REG
1148 /* If we usually make new pseudos, do so here. This
1149 turns out to help machines that have conditional
1152 if (flag_expensive_optimizations
)
1155 target
= expand_binop (GET_MODE (var
), ior_optab
,
1159 else if (normalizep
!= 1)
1161 /* We know that either CVAL or UVAL is zero. If
1162 UVAL is zero, negate TARGET and `and' with CVAL.
1163 Otherwise, `and' with UVAL. */
1164 if (uval
== const0_rtx
)
1166 target
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1167 target
, NULL_RTX
, 0);
1171 target
= expand_and (uval
, target
,
1172 (GET_CODE (target
) == REG
1173 && ! preserve_subexpressions_p ()
1174 ? target
: NULL_RTX
));
1177 emit_move_insn (var
, target
);
1182 /* If INSN uses CC0, we must not separate it from the
1183 insn that sets cc0. */
1185 if (reg_mentioned_p (cc0_rtx
, PATTERN (before
)))
1186 before
= prev_nonnote_insn (before
);
1189 emit_insns_before (seq
, before
);
1192 next
= NEXT_INSN (insn
);
1202 /* If branches are expensive, convert
1203 if (foo) bar++; to bar += (foo != 0);
1204 and similarly for "bar--;"
1206 INSN is the conditional branch around the arithmetic. We set:
1208 TEMP is the arithmetic insn.
1209 TEMP1 is the SET doing the arithmetic.
1210 TEMP2 is the operand being incremented or decremented.
1211 TEMP3 to the condition being tested.
1212 TEMP4 to the earliest insn used to find the condition. */
1214 if ((BRANCH_COST
>= 2
1222 && ! reload_completed
1223 && this_is_condjump
&& ! this_is_simplejump
1224 && (temp
= next_nonnote_insn (insn
)) != 0
1225 && (temp1
= single_set (temp
)) != 0
1226 && (temp2
= SET_DEST (temp1
),
1227 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
1228 && GET_CODE (SET_SRC (temp1
)) == PLUS
1229 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1230 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
1231 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
1232 /* INSN must either branch to the insn after TEMP or the insn
1233 after TEMP must branch to the same place as INSN. */
1234 && (reallabelprev
== temp
1235 || ((temp3
= next_active_insn (temp
)) != 0
1236 && simplejump_p (temp3
)
1237 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
1238 && (temp3
= get_condition (insn
, &temp4
)) != 0
1239 /* We must be comparing objects whose modes imply the size.
1240 We could handle BLKmode if (1) emit_store_flag could
1241 and (2) we could find the size reliably. */
1242 && GET_MODE (XEXP (temp3
, 0)) != BLKmode
1243 && can_reverse_comparison_p (temp3
, insn
))
1245 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
1246 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
1250 /* It must be the case that TEMP2 is not modified in the range
1251 [TEMP4, INSN). The one exception we make is if the insn
1252 before INSN sets TEMP2 to something which is also unchanged
1253 in that range. In that case, we can move the initialization
1254 into our sequence. */
1256 if ((temp5
= prev_active_insn (insn
)) != 0
1257 && GET_CODE (temp5
) == INSN
1258 && (temp6
= single_set (temp5
)) != 0
1259 && rtx_equal_p (temp2
, SET_DEST (temp6
))
1260 && (CONSTANT_P (SET_SRC (temp6
))
1261 || GET_CODE (SET_SRC (temp6
)) == REG
1262 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
1264 emit_insn (PATTERN (temp5
));
1266 init
= SET_SRC (temp6
);
1269 if (CONSTANT_P (init
)
1270 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
1271 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
1272 XEXP (temp3
, 0), XEXP (temp3
, 1),
1274 (code
== LTU
|| code
== LEU
1275 || code
== GTU
|| code
== GEU
), 1);
1277 /* If we can do the store-flag, do the addition or
1281 target
= expand_binop (GET_MODE (temp2
),
1282 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1283 ? add_optab
: sub_optab
),
1284 temp2
, target
, temp2
, 0, OPTAB_WIDEN
);
1288 /* Put the result back in temp2 in case it isn't already.
1289 Then replace the jump, possible a CC0-setting insn in
1290 front of the jump, and TEMP, with the sequence we have
1293 if (target
!= temp2
)
1294 emit_move_insn (temp2
, target
);
1299 emit_insns_before (seq
, temp4
);
1303 delete_insn (init_insn
);
1305 next
= NEXT_INSN (insn
);
1307 delete_insn (prev_nonnote_insn (insn
));
1317 /* Simplify if (...) x = 1; else {...} if (x) ...
1318 We recognize this case scanning backwards as well.
1320 TEMP is the assignment to x;
1321 TEMP1 is the label at the head of the second if. */
1322 /* ?? This should call get_condition to find the values being
1323 compared, instead of looking for a COMPARE insn when HAVE_cc0
1324 is not defined. This would allow it to work on the m88k. */
1325 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1326 is not defined and the condition is tested by a separate compare
1327 insn. This is because the code below assumes that the result
1328 of the compare dies in the following branch.
1330 Not only that, but there might be other insns between the
1331 compare and branch whose results are live. Those insns need
1334 A way to fix this is to move the insns at JUMP_LABEL (insn)
1335 to before INSN. If we are running before flow, they will
1336 be deleted if they aren't needed. But this doesn't work
1339 This is really a special-case of jump threading, anyway. The
1340 right thing to do is to replace this and jump threading with
1341 much simpler code in cse.
1343 This code has been turned off in the non-cc0 case in the
1347 else if (this_is_simplejump
1348 /* Safe to skip USE and CLOBBER insns here
1349 since they will not be deleted. */
1350 && (temp
= prev_active_insn (insn
))
1351 && no_labels_between_p (temp
, insn
)
1352 && GET_CODE (temp
) == INSN
1353 && GET_CODE (PATTERN (temp
)) == SET
1354 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1355 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1356 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1357 /* If we find that the next value tested is `x'
1358 (TEMP1 is the insn where this happens), win. */
1359 && GET_CODE (temp1
) == INSN
1360 && GET_CODE (PATTERN (temp1
)) == SET
1362 /* Does temp1 `tst' the value of x? */
1363 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1364 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1365 && (temp1
= next_nonnote_insn (temp1
))
1367 /* Does temp1 compare the value of x against zero? */
1368 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1369 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1370 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1371 == SET_DEST (PATTERN (temp
)))
1372 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1373 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1375 && condjump_p (temp1
))
1377 /* Get the if_then_else from the condjump. */
1378 rtx choice
= SET_SRC (PATTERN (temp1
));
1379 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1381 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1382 rtx val
= SET_SRC (PATTERN (temp
));
1384 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1388 if (cond
== const_true_rtx
)
1389 ultimate
= XEXP (choice
, 1);
1390 else if (cond
== const0_rtx
)
1391 ultimate
= XEXP (choice
, 2);
1395 if (ultimate
== pc_rtx
)
1396 ultimate
= get_label_after (temp1
);
1397 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1398 ultimate
= XEXP (ultimate
, 0);
1401 changed
|= redirect_jump (insn
, ultimate
);
1407 /* @@ This needs a bit of work before it will be right.
1409 Any type of comparison can be accepted for the first and
1410 second compare. When rewriting the first jump, we must
1411 compute the what conditions can reach label3, and use the
1412 appropriate code. We can not simply reverse/swap the code
1413 of the first jump. In some cases, the second jump must be
1417 < == converts to > ==
1418 < != converts to == >
1421 If the code is written to only accept an '==' test for the second
1422 compare, then all that needs to be done is to swap the condition
1423 of the first branch.
1425 It is questionable whether we want this optimization anyways,
1426 since if the user wrote code like this because he/she knew that
1427 the jump to label1 is taken most of the time, then rewriting
1428 this gives slower code. */
1429 /* @@ This should call get_condition to find the values being
1430 compared, instead of looking for a COMPARE insn when HAVE_cc0
1431 is not defined. This would allow it to work on the m88k. */
1432 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1433 is not defined and the condition is tested by a separate compare
1434 insn. This is because the code below assumes that the result
1435 of the compare dies in the following branch. */
1437 /* Simplify test a ~= b
1451 where ~= is an inequality, e.g. >, and ~~= is the swapped
1454 We recognize this case scanning backwards.
1456 TEMP is the conditional jump to `label2';
1457 TEMP1 is the test for `a == b';
1458 TEMP2 is the conditional jump to `label1';
1459 TEMP3 is the test for `a ~= b'. */
1460 else if (this_is_simplejump
1461 && (temp
= prev_active_insn (insn
))
1462 && no_labels_between_p (temp
, insn
)
1463 && condjump_p (temp
)
1464 && (temp1
= prev_active_insn (temp
))
1465 && no_labels_between_p (temp1
, temp
)
1466 && GET_CODE (temp1
) == INSN
1467 && GET_CODE (PATTERN (temp1
)) == SET
1469 && sets_cc0_p (PATTERN (temp1
)) == 1
1471 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1472 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1473 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1475 && (temp2
= prev_active_insn (temp1
))
1476 && no_labels_between_p (temp2
, temp1
)
1477 && condjump_p (temp2
)
1478 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1479 && (temp3
= prev_active_insn (temp2
))
1480 && no_labels_between_p (temp3
, temp2
)
1481 && GET_CODE (PATTERN (temp3
)) == SET
1482 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1483 SET_DEST (PATTERN (temp1
)))
1484 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1485 SET_SRC (PATTERN (temp3
)))
1486 && ! inequality_comparisons_p (PATTERN (temp
))
1487 && inequality_comparisons_p (PATTERN (temp2
)))
1489 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1491 ++LABEL_NUSES (fallthrough_label
);
1492 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1498 if (--LABEL_NUSES (fallthrough_label
) == 0)
1499 delete_insn (fallthrough_label
);
1502 /* Simplify if (...) {... x = 1;} if (x) ...
1504 We recognize this case backwards.
1506 TEMP is the test of `x';
1507 TEMP1 is the assignment to `x' at the end of the
1508 previous statement. */
1509 /* @@ This should call get_condition to find the values being
1510 compared, instead of looking for a COMPARE insn when HAVE_cc0
1511 is not defined. This would allow it to work on the m88k. */
1512 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1513 is not defined and the condition is tested by a separate compare
1514 insn. This is because the code below assumes that the result
1515 of the compare dies in the following branch. */
1517 /* ??? This has to be turned off. The problem is that the
1518 unconditional jump might indirectly end up branching to the
1519 label between TEMP1 and TEMP. We can't detect this, in general,
1520 since it may become a jump to there after further optimizations.
1521 If that jump is done, it will be deleted, so we will retry
1522 this optimization in the next pass, thus an infinite loop.
1524 The present code prevents this by putting the jump after the
1525 label, but this is not logically correct. */
1527 else if (this_is_condjump
1528 /* Safe to skip USE and CLOBBER insns here
1529 since they will not be deleted. */
1530 && (temp
= prev_active_insn (insn
))
1531 && no_labels_between_p (temp
, insn
)
1532 && GET_CODE (temp
) == INSN
1533 && GET_CODE (PATTERN (temp
)) == SET
1535 && sets_cc0_p (PATTERN (temp
)) == 1
1536 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1538 /* Temp must be a compare insn, we can not accept a register
1539 to register move here, since it may not be simply a
1541 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1542 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1543 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1544 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1545 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1547 /* May skip USE or CLOBBER insns here
1548 for checking for opportunity, since we
1549 take care of them later. */
1550 && (temp1
= prev_active_insn (temp
))
1551 && GET_CODE (temp1
) == INSN
1552 && GET_CODE (PATTERN (temp1
)) == SET
1554 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1556 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1557 == SET_DEST (PATTERN (temp1
)))
1559 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1560 /* If this isn't true, cse will do the job. */
1561 && ! no_labels_between_p (temp1
, temp
))
1563 /* Get the if_then_else from the condjump. */
1564 rtx choice
= SET_SRC (PATTERN (insn
));
1565 if (GET_CODE (choice
) == IF_THEN_ELSE
1566 && (GET_CODE (XEXP (choice
, 0)) == EQ
1567 || GET_CODE (XEXP (choice
, 0)) == NE
))
1569 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1574 /* Get the place that condjump will jump to
1575 if it is reached from here. */
1576 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1578 ultimate
= XEXP (choice
, 1);
1580 ultimate
= XEXP (choice
, 2);
1581 /* Get it as a CODE_LABEL. */
1582 if (ultimate
== pc_rtx
)
1583 ultimate
= get_label_after (insn
);
1585 /* Get the label out of the LABEL_REF. */
1586 ultimate
= XEXP (ultimate
, 0);
1588 /* Insert the jump immediately before TEMP, specifically
1589 after the label that is between TEMP1 and TEMP. */
1590 last_insn
= PREV_INSN (temp
);
1592 /* If we would be branching to the next insn, the jump
1593 would immediately be deleted and the re-inserted in
1594 a subsequent pass over the code. So don't do anything
1596 if (next_active_insn (last_insn
)
1597 != next_active_insn (ultimate
))
1599 emit_barrier_after (last_insn
);
1600 p
= emit_jump_insn_after (gen_jump (ultimate
),
1602 JUMP_LABEL (p
) = ultimate
;
1603 ++LABEL_NUSES (ultimate
);
1604 if (INSN_UID (ultimate
) < max_jump_chain
1605 && INSN_CODE (p
) < max_jump_chain
)
1607 jump_chain
[INSN_UID (p
)]
1608 = jump_chain
[INSN_UID (ultimate
)];
1609 jump_chain
[INSN_UID (ultimate
)] = p
;
1617 /* Detect a conditional jump going to the same place
1618 as an immediately following unconditional jump. */
1619 else if (this_is_condjump
1620 && (temp
= next_active_insn (insn
)) != 0
1621 && simplejump_p (temp
)
1622 && (next_active_insn (JUMP_LABEL (insn
))
1623 == next_active_insn (JUMP_LABEL (temp
))))
1629 /* Detect a conditional jump jumping over an unconditional jump. */
1631 else if (this_is_condjump
&& ! this_is_simplejump
1632 && reallabelprev
!= 0
1633 && GET_CODE (reallabelprev
) == JUMP_INSN
1634 && prev_active_insn (reallabelprev
) == insn
1635 && no_labels_between_p (insn
, reallabelprev
)
1636 && simplejump_p (reallabelprev
))
1638 /* When we invert the unconditional jump, we will be
1639 decrementing the usage count of its old label.
1640 Make sure that we don't delete it now because that
1641 might cause the following code to be deleted. */
1642 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
1643 rtx prev_label
= JUMP_LABEL (insn
);
1645 ++LABEL_NUSES (prev_label
);
1647 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
1649 /* It is very likely that if there are USE insns before
1650 this jump, they hold REG_DEAD notes. These REG_DEAD
1651 notes are no longer valid due to this optimization,
1652 and will cause the life-analysis that following passes
1653 (notably delayed-branch scheduling) to think that
1654 these registers are dead when they are not.
1656 To prevent this trouble, we just remove the USE insns
1657 from the insn chain. */
1659 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
1660 && GET_CODE (PATTERN (prev_uses
)) == USE
)
1662 rtx useless
= prev_uses
;
1663 prev_uses
= prev_nonnote_insn (prev_uses
);
1664 delete_insn (useless
);
1667 delete_insn (reallabelprev
);
1672 /* We can now safely delete the label if it is unreferenced
1673 since the delete_insn above has deleted the BARRIER. */
1674 if (--LABEL_NUSES (prev_label
) == 0)
1675 delete_insn (prev_label
);
1680 /* Detect a jump to a jump. */
1682 nlabel
= follow_jumps (JUMP_LABEL (insn
));
1683 if (nlabel
!= JUMP_LABEL (insn
)
1684 && redirect_jump (insn
, nlabel
))
1690 /* Look for if (foo) bar; else break; */
1691 /* The insns look like this:
1692 insn = condjump label1;
1693 ...range1 (some insns)...
1696 ...range2 (some insns)...
1697 jump somewhere unconditionally
1700 rtx label1
= next_label (insn
);
1701 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1702 /* Don't do this optimization on the first round, so that
1703 jump-around-a-jump gets simplified before we ask here
1704 whether a jump is unconditional.
1706 Also don't do it when we are called after reload since
1707 it will confuse reorg. */
1709 && (reload_completed
? ! flag_delayed_branch
: 1)
1710 /* Make sure INSN is something we can invert. */
1711 && condjump_p (insn
)
1713 && JUMP_LABEL (insn
) == label1
1714 && LABEL_NUSES (label1
) == 1
1715 && GET_CODE (range1end
) == JUMP_INSN
1716 && simplejump_p (range1end
))
1718 rtx label2
= next_label (label1
);
1719 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
1720 if (range1end
!= range2end
1721 && JUMP_LABEL (range1end
) == label2
1722 && GET_CODE (range2end
) == JUMP_INSN
1723 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
1724 /* Invert the jump condition, so we
1725 still execute the same insns in each case. */
1726 && invert_jump (insn
, label1
))
1728 rtx range1beg
= next_active_insn (insn
);
1729 rtx range2beg
= next_active_insn (label1
);
1730 rtx range1after
, range2after
;
1731 rtx range1before
, range2before
;
1733 /* Include in each range any line number before it. */
1734 while (PREV_INSN (range1beg
)
1735 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
1736 && NOTE_LINE_NUMBER (PREV_INSN (range1beg
)) > 0)
1737 range1beg
= PREV_INSN (range1beg
);
1739 while (PREV_INSN (range2beg
)
1740 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
1741 && NOTE_LINE_NUMBER (PREV_INSN (range2beg
)) > 0)
1742 range2beg
= PREV_INSN (range2beg
);
1744 /* Don't move NOTEs for blocks or loops; shift them
1745 outside the ranges, where they'll stay put. */
1746 range1beg
= squeeze_notes (range1beg
, range1end
);
1747 range2beg
= squeeze_notes (range2beg
, range2end
);
1749 /* Get current surrounds of the 2 ranges. */
1750 range1before
= PREV_INSN (range1beg
);
1751 range2before
= PREV_INSN (range2beg
);
1752 range1after
= NEXT_INSN (range1end
);
1753 range2after
= NEXT_INSN (range2end
);
1755 /* Splice range2 where range1 was. */
1756 NEXT_INSN (range1before
) = range2beg
;
1757 PREV_INSN (range2beg
) = range1before
;
1758 NEXT_INSN (range2end
) = range1after
;
1759 PREV_INSN (range1after
) = range2end
;
1760 /* Splice range1 where range2 was. */
1761 NEXT_INSN (range2before
) = range1beg
;
1762 PREV_INSN (range1beg
) = range2before
;
1763 NEXT_INSN (range1end
) = range2after
;
1764 PREV_INSN (range2after
) = range1end
;
1771 /* Now that the jump has been tensioned,
1772 try cross jumping: check for identical code
1773 before the jump and before its target label. */
1775 /* First, cross jumping of conditional jumps: */
1777 if (cross_jump
&& condjump_p (insn
))
1779 rtx newjpos
, newlpos
;
1780 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
1782 /* A conditional jump may be crossjumped
1783 only if the place it jumps to follows
1784 an opposing jump that comes back here. */
1786 if (x
!= 0 && ! jump_back_p (x
, insn
))
1787 /* We have no opposing jump;
1788 cannot cross jump this insn. */
1792 /* TARGET is nonzero if it is ok to cross jump
1793 to code before TARGET. If so, see if matches. */
1795 find_cross_jump (insn
, x
, 2,
1796 &newjpos
, &newlpos
);
1800 do_cross_jump (insn
, newjpos
, newlpos
);
1801 /* Make the old conditional jump
1802 into an unconditional one. */
1803 SET_SRC (PATTERN (insn
))
1804 = gen_rtx (LABEL_REF
, VOIDmode
, JUMP_LABEL (insn
));
1805 INSN_CODE (insn
) = -1;
1806 emit_barrier_after (insn
);
1807 /* Add to jump_chain unless this is a new label
1808 whose UID is too large. */
1809 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
1811 jump_chain
[INSN_UID (insn
)]
1812 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1813 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
1820 /* Cross jumping of unconditional jumps:
1821 a few differences. */
1823 if (cross_jump
&& simplejump_p (insn
))
1825 rtx newjpos
, newlpos
;
1830 /* TARGET is nonzero if it is ok to cross jump
1831 to code before TARGET. If so, see if matches. */
1832 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
1833 &newjpos
, &newlpos
);
1835 /* If cannot cross jump to code before the label,
1836 see if we can cross jump to another jump to
1838 /* Try each other jump to this label. */
1839 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
1840 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1841 target
!= 0 && newjpos
== 0;
1842 target
= jump_chain
[INSN_UID (target
)])
1844 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
1845 /* Ignore TARGET if it's deleted. */
1846 && ! INSN_DELETED_P (target
))
1847 find_cross_jump (insn
, target
, 2,
1848 &newjpos
, &newlpos
);
1852 do_cross_jump (insn
, newjpos
, newlpos
);
1858 /* This code was dead in the previous jump.c! */
1859 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
1861 /* Return insns all "jump to the same place"
1862 so we can cross-jump between any two of them. */
1864 rtx newjpos
, newlpos
, target
;
1868 /* If cannot cross jump to code before the label,
1869 see if we can cross jump to another jump to
1871 /* Try each other jump to this label. */
1872 for (target
= jump_chain
[0];
1873 target
!= 0 && newjpos
== 0;
1874 target
= jump_chain
[INSN_UID (target
)])
1876 && ! INSN_DELETED_P (target
)
1877 && GET_CODE (PATTERN (target
)) == RETURN
)
1878 find_cross_jump (insn
, target
, 2,
1879 &newjpos
, &newlpos
);
1883 do_cross_jump (insn
, newjpos
, newlpos
);
1894 /* Delete extraneous line number notes.
1895 Note that two consecutive notes for different lines are not really
1896 extraneous. There should be some indication where that line belonged,
1897 even if it became empty. */
1902 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
1903 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
1905 /* Delete this note if it is identical to previous note. */
1907 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
1908 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
1918 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1919 If so, delete it, and record that this function can drop off the end. */
1925 /* One label can follow the end-note: the return label. */
1926 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
1927 /* Ordinary insns can follow it if returning a structure. */
1928 || GET_CODE (insn
) == INSN
1929 /* If machine uses explicit RETURN insns, no epilogue,
1930 then one of them follows the note. */
1931 || (GET_CODE (insn
) == JUMP_INSN
1932 && GET_CODE (PATTERN (insn
)) == RETURN
)
1933 /* Other kinds of notes can follow also. */
1934 || (GET_CODE (insn
) == NOTE
1935 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
1936 insn
= PREV_INSN (insn
);
1939 /* Report if control can fall through at the end of the function. */
1940 if (insn
&& GET_CODE (insn
) == NOTE
1941 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
)
1947 /* Show JUMP_CHAIN no longer valid. */
1951 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1952 jump. Assume that this unconditional jump is to the exit test code. If
1953 the code is sufficiently simple, make a copy of it before INSN,
1954 followed by a jump to the exit of the loop. Then delete the unconditional
1957 Note that it is possible we can get confused here if the jump immediately
1958 after the loop start branches outside the loop but within an outer loop.
1959 If we are near the exit of that loop, we will copy its exit test. This
1960 will not generate incorrect code, but could suppress some optimizations.
1961 However, such cases are degenerate loops anyway.
1963 Return 1 if we made the change, else 0.
1965 This is only safe immediately after a regscan pass because it uses the
1966 values of regno_first_uid and regno_last_uid. */
1969 duplicate_loop_exit_test (loop_start
)
1975 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
1977 int max_reg
= max_reg_num ();
1980 /* Scan the exit code. We do not perform this optimization if any insn:
1984 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1985 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1986 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1989 Also, don't do this if the exit code is more than 20 insns. */
1991 for (insn
= exitcode
;
1993 && ! (GET_CODE (insn
) == NOTE
1994 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
1995 insn
= NEXT_INSN (insn
))
1997 switch (GET_CODE (insn
))
2003 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2004 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2005 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
2010 if (++num_insns
> 20
2011 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
2012 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2018 /* Unless INSN is zero, we can do the optimization. */
2024 /* See if any insn sets a register only used in the loop exit code and
2025 not a user variable. If so, replace it with a new register. */
2026 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2027 if (GET_CODE (insn
) == INSN
2028 && (set
= single_set (insn
)) != 0
2029 && GET_CODE (SET_DEST (set
)) == REG
2030 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
2031 && regno_first_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
))
2033 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
2034 if (regno_last_uid
[REGNO (SET_DEST (set
))] == INSN_UID (p
))
2039 /* We can do the replacement. Allocate reg_map if this is the
2040 first replacement we found. */
2043 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
2044 bzero (reg_map
, max_reg
* sizeof (rtx
));
2047 REG_LOOP_TEST_P (SET_DEST (set
)) = 1;
2049 reg_map
[REGNO (SET_DEST (set
))]
2050 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
2054 /* Now copy each insn. */
2055 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2056 switch (GET_CODE (insn
))
2059 copy
= emit_barrier_before (loop_start
);
2062 /* Only copy line-number notes. */
2063 if (NOTE_LINE_NUMBER (insn
) >= 0)
2065 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
2066 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
2071 copy
= emit_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2073 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2075 mark_jump_label (PATTERN (copy
), copy
, 0);
2077 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2079 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2080 if (REG_NOTE_KIND (link
) != REG_LABEL
)
2082 = copy_rtx (gen_rtx (EXPR_LIST
, REG_NOTE_KIND (link
),
2083 XEXP (link
, 0), REG_NOTES (copy
)));
2084 if (reg_map
&& REG_NOTES (copy
))
2085 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2089 copy
= emit_jump_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2091 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2092 mark_jump_label (PATTERN (copy
), copy
, 0);
2093 if (REG_NOTES (insn
))
2095 REG_NOTES (copy
) = copy_rtx (REG_NOTES (insn
));
2097 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2100 /* If this is a simple jump, add it to the jump chain. */
2102 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
2103 && simplejump_p (copy
))
2105 jump_chain
[INSN_UID (copy
)]
2106 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2107 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2115 /* Now clean up by emitting a jump to the end label and deleting the jump
2116 at the start of the loop. */
2117 if (GET_CODE (copy
) != BARRIER
)
2119 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
2121 mark_jump_label (PATTERN (copy
), copy
, 0);
2122 if (INSN_UID (copy
) < max_jump_chain
2123 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
2125 jump_chain
[INSN_UID (copy
)]
2126 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2127 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2129 emit_barrier_before (loop_start
);
2132 delete_insn (next_nonnote_insn (loop_start
));
2134 /* Mark the exit code as the virtual top of the converted loop. */
2135 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
2140 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2141 loop-end notes between START and END out before START. Assume that
2142 END is not such a note. START may be such a note. Returns the value
2143 of the new starting insn, which may be different if the original start
2147 squeeze_notes (start
, end
)
2153 for (insn
= start
; insn
!= end
; insn
= next
)
2155 next
= NEXT_INSN (insn
);
2156 if (GET_CODE (insn
) == NOTE
2157 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2158 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2159 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2160 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
2161 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
2162 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
2168 rtx prev
= PREV_INSN (insn
);
2169 PREV_INSN (insn
) = PREV_INSN (start
);
2170 NEXT_INSN (insn
) = start
;
2171 NEXT_INSN (PREV_INSN (insn
)) = insn
;
2172 PREV_INSN (NEXT_INSN (insn
)) = insn
;
2173 NEXT_INSN (prev
) = next
;
2174 PREV_INSN (next
) = prev
;
2182 /* Compare the instructions before insn E1 with those before E2
2183 to find an opportunity for cross jumping.
2184 (This means detecting identical sequences of insns followed by
2185 jumps to the same place, or followed by a label and a jump
2186 to that label, and replacing one with a jump to the other.)
2188 Assume E1 is a jump that jumps to label E2
2189 (that is not always true but it might as well be).
2190 Find the longest possible equivalent sequences
2191 and store the first insns of those sequences into *F1 and *F2.
2192 Store zero there if no equivalent preceding instructions are found.
2194 We give up if we find a label in stream 1.
2195 Actually we could transfer that label into stream 2. */
2198 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
2203 register rtx i1
= e1
, i2
= e2
;
2204 register rtx p1
, p2
;
2207 rtx last1
= 0, last2
= 0;
2208 rtx afterlast1
= 0, afterlast2
= 0;
2216 i1
= prev_nonnote_insn (i1
);
2218 i2
= PREV_INSN (i2
);
2219 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
2220 i2
= PREV_INSN (i2
);
2225 /* Don't allow the range of insns preceding E1 or E2
2226 to include the other (E2 or E1). */
2227 if (i2
== e1
|| i1
== e2
)
2230 /* If we will get to this code by jumping, those jumps will be
2231 tensioned to go directly to the new label (before I2),
2232 so this cross-jumping won't cost extra. So reduce the minimum. */
2233 if (GET_CODE (i1
) == CODE_LABEL
)
2239 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
2246 /* If cross_jump_death_matters is not 0, the insn's mode
2247 indicates whether or not the insn contains any stack-like
2250 if (cross_jump_death_matters
&& GET_MODE (i1
) == QImode
)
2252 /* If register stack conversion has already been done, then
2253 death notes must also be compared before it is certain that
2254 the two instruction streams match. */
2257 HARD_REG_SET i1_regset
, i2_regset
;
2259 CLEAR_HARD_REG_SET (i1_regset
);
2260 CLEAR_HARD_REG_SET (i2_regset
);
2262 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
2263 if (REG_NOTE_KIND (note
) == REG_DEAD
2264 && STACK_REG_P (XEXP (note
, 0)))
2265 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
2267 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
2268 if (REG_NOTE_KIND (note
) == REG_DEAD
2269 && STACK_REG_P (XEXP (note
, 0)))
2270 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
2272 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
2281 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
2282 || ! rtx_renumbered_equal_p (p1
, p2
))
2284 /* The following code helps take care of G++ cleanups. */
2288 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
2289 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
2290 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
2291 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
2292 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
2293 /* If the equivalences are not to a constant, they may
2294 reference pseudos that no longer exist, so we can't
2296 && CONSTANT_P (XEXP (equiv1
, 0))
2297 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
2299 rtx s1
= single_set (i1
);
2300 rtx s2
= single_set (i2
);
2301 if (s1
!= 0 && s2
!= 0
2302 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
2304 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
2305 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
2306 if (! rtx_renumbered_equal_p (p1
, p2
))
2308 else if (apply_change_group ())
2313 /* Insns fail to match; cross jumping is limited to the following
2317 /* Don't allow the insn after a compare to be shared by
2318 cross-jumping unless the compare is also shared.
2319 Here, if either of these non-matching insns is a compare,
2320 exclude the following insn from possible cross-jumping. */
2321 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
2322 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
2325 /* If cross-jumping here will feed a jump-around-jump
2326 optimization, this jump won't cost extra, so reduce
2328 if (GET_CODE (i1
) == JUMP_INSN
2330 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
2336 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
2338 /* Ok, this insn is potentially includable in a cross-jump here. */
2339 afterlast1
= last1
, afterlast2
= last2
;
2340 last1
= i1
, last2
= i2
, --minimum
;
2344 /* We have to be careful that we do not cross-jump into the middle of
2345 USE-CALL_INSN-CLOBBER sequence. This sequence is used instead of
2346 putting the USE and CLOBBERs inside the CALL_INSN. The delay slot
2347 scheduler needs to know what registers are used and modified by the
2348 CALL_INSN and needs the adjacent USE and CLOBBERs to do so.
2350 ??? At some point we should probably change this so that these are
2351 part of the CALL_INSN. The way we are doing it now is a kludge that
2352 is now causing trouble. */
2354 if (last1
!= 0 && GET_CODE (last1
) == CALL_INSN
2355 && (prev1
= prev_nonnote_insn (last1
))
2356 && GET_CODE (prev1
) == INSN
2357 && GET_CODE (PATTERN (prev1
)) == USE
)
2359 /* Remove this CALL_INSN from the range we can cross-jump. */
2360 last1
= next_real_insn (last1
);
2361 last2
= next_real_insn (last2
);
2366 /* Skip past CLOBBERS since they may be right after a CALL_INSN. It
2367 isn't worth checking for the CALL_INSN. */
2368 while (last1
!= 0 && GET_CODE (PATTERN (last1
)) == CLOBBER
)
2369 last1
= next_real_insn (last1
), last2
= next_real_insn (last2
);
2371 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
2372 *f1
= last1
, *f2
= last2
;
2376 do_cross_jump (insn
, newjpos
, newlpos
)
2377 rtx insn
, newjpos
, newlpos
;
2379 /* Find an existing label at this point
2380 or make a new one if there is none. */
2381 register rtx label
= get_label_before (newlpos
);
2383 /* Make the same jump insn jump to the new point. */
2384 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2386 /* Remove from jump chain of returns. */
2387 delete_from_jump_chain (insn
);
2388 /* Change the insn. */
2389 PATTERN (insn
) = gen_jump (label
);
2390 INSN_CODE (insn
) = -1;
2391 JUMP_LABEL (insn
) = label
;
2392 LABEL_NUSES (label
)++;
2393 /* Add to new the jump chain. */
2394 if (INSN_UID (label
) < max_jump_chain
2395 && INSN_UID (insn
) < max_jump_chain
)
2397 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
2398 jump_chain
[INSN_UID (label
)] = insn
;
2402 redirect_jump (insn
, label
);
2404 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2405 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2406 the NEWJPOS stream. */
2408 while (newjpos
!= insn
)
2412 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
2413 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
2414 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
2415 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
2416 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
2417 remove_note (newlpos
, lnote
);
2419 delete_insn (newjpos
);
2420 newjpos
= next_real_insn (newjpos
);
2421 newlpos
= next_real_insn (newlpos
);
2425 /* Return the label before INSN, or put a new label there. */
2428 get_label_before (insn
)
2433 /* Find an existing label at this point
2434 or make a new one if there is none. */
2435 label
= prev_nonnote_insn (insn
);
2437 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2439 rtx prev
= PREV_INSN (insn
);
2441 /* Don't put a label between a CALL_INSN and USE insns that precede
2444 if (GET_CODE (insn
) == CALL_INSN
2445 || (GET_CODE (insn
) == INSN
&& GET_CODE (PATTERN (insn
)) == SEQUENCE
2446 && GET_CODE (XVECEXP (PATTERN (insn
), 0, 0)) == CALL_INSN
))
2447 while (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == USE
)
2448 prev
= PREV_INSN (prev
);
2450 label
= gen_label_rtx ();
2451 emit_label_after (label
, prev
);
2452 LABEL_NUSES (label
) = 0;
2457 /* Return the label after INSN, or put a new label there. */
2460 get_label_after (insn
)
2465 /* Find an existing label at this point
2466 or make a new one if there is none. */
2467 label
= next_nonnote_insn (insn
);
2469 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2471 /* Don't put a label between a CALL_INSN and CLOBBER insns
2474 if (GET_CODE (insn
) == CALL_INSN
2475 || (GET_CODE (insn
) == INSN
&& GET_CODE (PATTERN (insn
)) == SEQUENCE
2476 && GET_CODE (XVECEXP (PATTERN (insn
), 0, 0)) == CALL_INSN
))
2477 while (GET_CODE (NEXT_INSN (insn
)) == INSN
2478 && GET_CODE (PATTERN (NEXT_INSN (insn
))) == CLOBBER
)
2479 insn
= NEXT_INSN (insn
);
2481 label
= gen_label_rtx ();
2482 emit_label_after (label
, insn
);
2483 LABEL_NUSES (label
) = 0;
2488 /* Return 1 if INSN is a jump that jumps to right after TARGET
2489 only on the condition that TARGET itself would drop through.
2490 Assumes that TARGET is a conditional jump. */
2493 jump_back_p (insn
, target
)
2497 enum rtx_code codei
, codet
;
2499 if (simplejump_p (insn
) || ! condjump_p (insn
)
2500 || simplejump_p (target
)
2501 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
2504 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
2505 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
2507 codei
= GET_CODE (cinsn
);
2508 codet
= GET_CODE (ctarget
);
2510 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
2512 if (! can_reverse_comparison_p (cinsn
, insn
))
2514 codei
= reverse_condition (codei
);
2517 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
2519 if (! can_reverse_comparison_p (ctarget
, target
))
2521 codet
= reverse_condition (codet
);
2524 return (codei
== codet
2525 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
2526 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
2529 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2530 return non-zero if it is safe to reverse this comparison. It is if our
2531 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2532 this is known to be an integer comparison. */
2535 can_reverse_comparison_p (comparison
, insn
)
2541 /* If this is not actually a comparison, we can't reverse it. */
2542 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
2545 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
2546 /* If this is an NE comparison, it is safe to reverse it to an EQ
2547 comparison and vice versa, even for floating point. If no operands
2548 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2549 always false and NE is always true, so the reversal is also valid. */
2550 || GET_CODE (comparison
) == NE
2551 || GET_CODE (comparison
) == EQ
)
2554 arg0
= XEXP (comparison
, 0);
2556 /* Make sure ARG0 is one of the actual objects being compared. If we
2557 can't do this, we can't be sure the comparison can be reversed.
2559 Handle cc0 and a MODE_CC register. */
2560 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
2566 rtx prev
= prev_nonnote_insn (insn
);
2567 rtx set
= single_set (prev
);
2569 if (set
== 0 || SET_DEST (set
) != arg0
)
2572 arg0
= SET_SRC (set
);
2574 if (GET_CODE (arg0
) == COMPARE
)
2575 arg0
= XEXP (arg0
, 0);
2578 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2579 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2580 return (GET_CODE (arg0
) == CONST_INT
2581 || (GET_MODE (arg0
) != VOIDmode
2582 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
2583 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
2586 /* Given an rtx-code for a comparison, return the code
2587 for the negated comparison.
2588 WATCH OUT! reverse_condition is not safe to use on a jump
2589 that might be acting on the results of an IEEE floating point comparison,
2590 because of the special treatment of non-signaling nans in comparisons.
2591 Use can_reverse_comparison_p to be sure. */
2594 reverse_condition (code
)
2635 /* Similar, but return the code when two operands of a comparison are swapped.
2636 This IS safe for IEEE floating-point. */
2639 swap_condition (code
)
2678 /* Given a comparison CODE, return the corresponding unsigned comparison.
2679 If CODE is an equality comparison or already an unsigned comparison,
2680 CODE is returned. */
2683 unsigned_condition (code
)
2713 /* Similarly, return the signed version of a comparison. */
2716 signed_condition (code
)
2746 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2747 truth of CODE1 implies the truth of CODE2. */
2750 comparison_dominates_p (code1
, code2
)
2751 enum rtx_code code1
, code2
;
2759 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
2787 /* Return 1 if INSN is an unconditional jump and nothing else. */
2793 return (GET_CODE (insn
) == JUMP_INSN
2794 && GET_CODE (PATTERN (insn
)) == SET
2795 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
2796 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
2799 /* Return nonzero if INSN is a (possibly) conditional jump
2800 and nothing more. */
2806 register rtx x
= PATTERN (insn
);
2807 if (GET_CODE (x
) != SET
)
2809 if (GET_CODE (SET_DEST (x
)) != PC
)
2811 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2813 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2815 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2816 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2817 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2819 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2820 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2821 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2826 /* Return 1 if X is an RTX that does nothing but set the condition codes
2827 and CLOBBER or USE registers.
2828 Return -1 if X does explicitly set the condition codes,
2829 but also does other things. */
2836 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
2838 if (GET_CODE (x
) == PARALLEL
)
2842 int other_things
= 0;
2843 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2845 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
2846 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
2848 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
2851 return ! sets_cc0
? 0 : other_things
? -1 : 1;
2859 /* Follow any unconditional jump at LABEL;
2860 return the ultimate label reached by any such chain of jumps.
2861 If LABEL is not followed by a jump, return LABEL.
2862 If the chain loops or we can't find end, return LABEL,
2863 since that tells caller to avoid changing the insn.
2865 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2866 a USE or CLOBBER. */
2869 follow_jumps (label
)
2874 register rtx value
= label
;
2879 && (insn
= next_active_insn (value
)) != 0
2880 && GET_CODE (insn
) == JUMP_INSN
2881 && (JUMP_LABEL (insn
) != 0 || GET_CODE (PATTERN (insn
)) == RETURN
)
2882 && (next
= NEXT_INSN (insn
))
2883 && GET_CODE (next
) == BARRIER
);
2886 /* Don't chain through the insn that jumps into a loop
2887 from outside the loop,
2888 since that would create multiple loop entry jumps
2889 and prevent loop optimization. */
2891 if (!reload_completed
)
2892 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
2893 if (GET_CODE (tem
) == NOTE
2894 && NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
)
2897 /* If we have found a cycle, make the insn jump to itself. */
2898 if (JUMP_LABEL (insn
) == label
)
2900 value
= JUMP_LABEL (insn
);
2907 /* Assuming that field IDX of X is a vector of label_refs,
2908 replace each of them by the ultimate label reached by it.
2909 Return nonzero if a change is made.
2910 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2913 tension_vector_labels (x
, idx
)
2919 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
2921 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
2922 register rtx nlabel
= follow_jumps (olabel
);
2923 if (nlabel
&& nlabel
!= olabel
)
2925 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
2926 ++LABEL_NUSES (nlabel
);
2927 if (--LABEL_NUSES (olabel
) == 0)
2928 delete_insn (olabel
);
2935 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2936 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2937 in INSN, then store one of them in JUMP_LABEL (INSN).
2938 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2939 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2940 Also, when there are consecutive labels, canonicalize on the last of them.
2942 Note that two labels separated by a loop-beginning note
2943 must be kept distinct if we have not yet done loop-optimization,
2944 because the gap between them is where loop-optimize
2945 will want to move invariant code to. CROSS_JUMP tells us
2946 that loop-optimization is done with.
2948 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2949 two labels distinct if they are separated by only USE or CLOBBER insns. */
2952 mark_jump_label (x
, insn
, cross_jump
)
2957 register RTX_CODE code
= GET_CODE (x
);
2975 /* If this is a constant-pool reference, see if it is a label. */
2976 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
2977 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
2978 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
2983 register rtx label
= XEXP (x
, 0);
2985 if (GET_CODE (label
) != CODE_LABEL
)
2987 /* Ignore references to labels of containing functions. */
2988 if (LABEL_REF_NONLOCAL_P (x
))
2990 /* If there are other labels following this one,
2991 replace it with the last of the consecutive labels. */
2992 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
2994 if (GET_CODE (next
) == CODE_LABEL
)
2996 else if (cross_jump
&& GET_CODE (next
) == INSN
2997 && (GET_CODE (PATTERN (next
)) == USE
2998 || GET_CODE (PATTERN (next
)) == CLOBBER
))
3000 else if (GET_CODE (next
) != NOTE
)
3002 else if (! cross_jump
3003 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
3004 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
))
3007 XEXP (x
, 0) = label
;
3008 ++LABEL_NUSES (label
);
3011 if (GET_CODE (insn
) == JUMP_INSN
)
3012 JUMP_LABEL (insn
) = label
;
3013 else if (! find_reg_note (insn
, REG_LABEL
, label
))
3015 rtx next
= next_real_insn (label
);
3016 /* Don't record labels that refer to dispatch tables.
3017 This is not necessary, since the tablejump
3018 references the same label.
3019 And if we did record them, flow.c would make worse code. */
3021 || ! (GET_CODE (next
) == JUMP_INSN
3022 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
3023 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
)))
3025 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_LABEL
, label
,
3027 /* Record in the note whether label is nonlocal. */
3028 LABEL_REF_NONLOCAL_P (REG_NOTES (insn
))
3029 = LABEL_REF_NONLOCAL_P (x
);
3036 /* Do walk the labels in a vector, but not the first operand of an
3037 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3041 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
3043 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
3044 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
, cross_jump
);
3049 fmt
= GET_RTX_FORMAT (code
);
3050 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3053 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
3054 else if (fmt
[i
] == 'E')
3057 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3058 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
3063 /* If all INSN does is set the pc, delete it,
3064 and delete the insn that set the condition codes for it
3065 if that's what the previous thing was. */
3071 register rtx set
= single_set (insn
);
3073 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3074 delete_computation (insn
);
3077 /* Delete INSN and recursively delete insns that compute values used only
3078 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3079 If we are running before flow.c, we need do nothing since flow.c will
3080 delete dead code. We also can't know if the registers being used are
3081 dead or not at this point.
3083 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3084 nothing other than set a register that dies in this insn, we can delete
3087 On machines with CC0, if CC0 is used in this insn, we may be able to
3088 delete the insn that set it. */
3091 delete_computation (insn
)
3097 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
3099 rtx prev
= prev_nonnote_insn (insn
);
3100 /* We assume that at this stage
3101 CC's are always set explicitly
3102 and always immediately before the jump that
3103 will use them. So if the previous insn
3104 exists to set the CC's, delete it
3105 (unless it performs auto-increments, etc.). */
3106 if (prev
&& GET_CODE (prev
) == INSN
3107 && sets_cc0_p (PATTERN (prev
)))
3109 if (sets_cc0_p (PATTERN (prev
)) > 0
3110 && !FIND_REG_INC_NOTE (prev
, NULL_RTX
))
3111 delete_computation (prev
);
3113 /* Otherwise, show that cc0 won't be used. */
3114 REG_NOTES (prev
) = gen_rtx (EXPR_LIST
, REG_UNUSED
,
3115 cc0_rtx
, REG_NOTES (prev
));
3120 for (note
= REG_NOTES (insn
); note
; note
= next
)
3124 next
= XEXP (note
, 1);
3126 if (REG_NOTE_KIND (note
) != REG_DEAD
3127 /* Verify that the REG_NOTE is legitimate. */
3128 || GET_CODE (XEXP (note
, 0)) != REG
)
3131 for (our_prev
= prev_nonnote_insn (insn
);
3132 our_prev
&& GET_CODE (our_prev
) == INSN
;
3133 our_prev
= prev_nonnote_insn (our_prev
))
3135 /* If we reach a SEQUENCE, it is too complex to try to
3136 do anything with it, so give up. */
3137 if (GET_CODE (PATTERN (our_prev
)) == SEQUENCE
)
3140 if (GET_CODE (PATTERN (our_prev
)) == USE
3141 && GET_CODE (XEXP (PATTERN (our_prev
), 0)) == INSN
)
3142 /* reorg creates USEs that look like this. We leave them
3143 alone because reorg needs them for its own purposes. */
3146 if (reg_set_p (XEXP (note
, 0), PATTERN (our_prev
)))
3148 if (FIND_REG_INC_NOTE (our_prev
, NULL_RTX
))
3151 if (GET_CODE (PATTERN (our_prev
)) == PARALLEL
)
3153 /* If we find a SET of something else, we can't
3158 for (i
= 0; i
< XVECLEN (PATTERN (our_prev
), 0); i
++)
3160 rtx part
= XVECEXP (PATTERN (our_prev
), 0, i
);
3162 if (GET_CODE (part
) == SET
3163 && SET_DEST (part
) != XEXP (note
, 0))
3167 if (i
== XVECLEN (PATTERN (our_prev
), 0))
3168 delete_computation (our_prev
);
3170 else if (GET_CODE (PATTERN (our_prev
)) == SET
3171 && SET_DEST (PATTERN (our_prev
)) == XEXP (note
, 0))
3172 delete_computation (our_prev
);
3177 /* If OUR_PREV references the register that dies here, it is an
3178 additional use. Hence any prior SET isn't dead. However, this
3179 insn becomes the new place for the REG_DEAD note. */
3180 if (reg_overlap_mentioned_p (XEXP (note
, 0),
3181 PATTERN (our_prev
)))
3183 XEXP (note
, 1) = REG_NOTES (our_prev
);
3184 REG_NOTES (our_prev
) = note
;
3193 /* Delete insn INSN from the chain of insns and update label ref counts.
3194 May delete some following insns as a consequence; may even delete
3195 a label elsewhere and insns that follow it.
3197 Returns the first insn after INSN that was not deleted. */
3203 register rtx next
= NEXT_INSN (insn
);
3204 register rtx prev
= PREV_INSN (insn
);
3205 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
3206 register int dont_really_delete
= 0;
3208 while (next
&& INSN_DELETED_P (next
))
3209 next
= NEXT_INSN (next
);
3211 /* This insn is already deleted => return first following nondeleted. */
3212 if (INSN_DELETED_P (insn
))
3215 /* Don't delete user-declared labels. Convert them to special NOTEs
3217 if (was_code_label
&& LABEL_NAME (insn
) != 0
3218 && optimize
&& ! dont_really_delete
)
3220 PUT_CODE (insn
, NOTE
);
3221 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
3222 NOTE_SOURCE_FILE (insn
) = 0;
3223 dont_really_delete
= 1;
3226 /* Mark this insn as deleted. */
3227 INSN_DELETED_P (insn
) = 1;
3229 /* If this is an unconditional jump, delete it from the jump chain. */
3230 if (simplejump_p (insn
))
3231 delete_from_jump_chain (insn
);
3233 /* If instruction is followed by a barrier,
3234 delete the barrier too. */
3236 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
3238 INSN_DELETED_P (next
) = 1;
3239 next
= NEXT_INSN (next
);
3242 /* Patch out INSN (and the barrier if any) */
3244 if (optimize
&& ! dont_really_delete
)
3248 NEXT_INSN (prev
) = next
;
3249 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
3250 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
3251 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
3256 PREV_INSN (next
) = prev
;
3257 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
3258 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
3261 if (prev
&& NEXT_INSN (prev
) == 0)
3262 set_last_insn (prev
);
3265 /* If deleting a jump, decrement the count of the label,
3266 and delete the label if it is now unused. */
3268 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
3269 if (--LABEL_NUSES (JUMP_LABEL (insn
)) == 0)
3271 /* This can delete NEXT or PREV,
3272 either directly if NEXT is JUMP_LABEL (INSN),
3273 or indirectly through more levels of jumps. */
3274 delete_insn (JUMP_LABEL (insn
));
3275 /* I feel a little doubtful about this loop,
3276 but I see no clean and sure alternative way
3277 to find the first insn after INSN that is not now deleted.
3278 I hope this works. */
3279 while (next
&& INSN_DELETED_P (next
))
3280 next
= NEXT_INSN (next
);
3284 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
3285 prev
= PREV_INSN (prev
);
3287 /* If INSN was a label and a dispatch table follows it,
3288 delete the dispatch table. The tablejump must have gone already.
3289 It isn't useful to fall through into a table. */
3292 && NEXT_INSN (insn
) != 0
3293 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
3294 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
3295 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
3296 next
= delete_insn (NEXT_INSN (insn
));
3298 /* If INSN was a label, delete insns following it if now unreachable. */
3300 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
3302 register RTX_CODE code
;
3304 && ((code
= GET_CODE (next
)) == INSN
3305 || code
== JUMP_INSN
|| code
== CALL_INSN
3307 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
3310 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
3311 next
= NEXT_INSN (next
);
3312 /* Keep going past other deleted labels to delete what follows. */
3313 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
3314 next
= NEXT_INSN (next
);
3316 /* Note: if this deletes a jump, it can cause more
3317 deletion of unreachable code, after a different label.
3318 As long as the value from this recursive call is correct,
3319 this invocation functions correctly. */
3320 next
= delete_insn (next
);
3327 /* Advance from INSN till reaching something not deleted
3328 then return that. May return INSN itself. */
3331 next_nondeleted_insn (insn
)
3334 while (INSN_DELETED_P (insn
))
3335 insn
= NEXT_INSN (insn
);
3339 /* Delete a range of insns from FROM to TO, inclusive.
3340 This is for the sake of peephole optimization, so assume
3341 that whatever these insns do will still be done by a new
3342 peephole insn that will replace them. */
3345 delete_for_peephole (from
, to
)
3346 register rtx from
, to
;
3348 register rtx insn
= from
;
3352 register rtx next
= NEXT_INSN (insn
);
3353 register rtx prev
= PREV_INSN (insn
);
3355 if (GET_CODE (insn
) != NOTE
)
3357 INSN_DELETED_P (insn
) = 1;
3359 /* Patch this insn out of the chain. */
3360 /* We don't do this all at once, because we
3361 must preserve all NOTEs. */
3363 NEXT_INSN (prev
) = next
;
3366 PREV_INSN (next
) = prev
;
3374 /* Note that if TO is an unconditional jump
3375 we *do not* delete the BARRIER that follows,
3376 since the peephole that replaces this sequence
3377 is also an unconditional jump in that case. */
3380 /* Invert the condition of the jump JUMP, and make it jump
3381 to label NLABEL instead of where it jumps now. */
3384 invert_jump (jump
, nlabel
)
3387 register rtx olabel
= JUMP_LABEL (jump
);
3389 /* We have to either invert the condition and change the label or
3390 do neither. Either operation could fail. We first try to invert
3391 the jump. If that succeeds, we try changing the label. If that fails,
3392 we invert the jump back to what it was. */
3394 if (! invert_exp (PATTERN (jump
), jump
))
3397 if (redirect_jump (jump
, nlabel
))
3400 if (! invert_exp (PATTERN (jump
), jump
))
3401 /* This should just be putting it back the way it was. */
3407 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3409 Return 1 if we can do so, 0 if we cannot find a way to do so that
3410 matches a pattern. */
3413 invert_exp (x
, insn
)
3417 register RTX_CODE code
;
3421 code
= GET_CODE (x
);
3423 if (code
== IF_THEN_ELSE
)
3425 register rtx comp
= XEXP (x
, 0);
3428 /* We can do this in two ways: The preferable way, which can only
3429 be done if this is not an integer comparison, is to reverse
3430 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3431 of the IF_THEN_ELSE. If we can't do either, fail. */
3433 if (can_reverse_comparison_p (comp
, insn
)
3434 && validate_change (insn
, &XEXP (x
, 0),
3435 gen_rtx (reverse_condition (GET_CODE (comp
)),
3436 GET_MODE (comp
), XEXP (comp
, 0),
3437 XEXP (comp
, 1)), 0))
3441 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
3442 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
3443 return apply_change_group ();
3446 fmt
= GET_RTX_FORMAT (code
);
3447 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3450 if (! invert_exp (XEXP (x
, i
), insn
))
3455 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3456 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
3464 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3465 If the old jump target label is unused as a result,
3466 it and the code following it may be deleted.
3468 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3471 The return value will be 1 if the change was made, 0 if it wasn't (this
3472 can only occur for NLABEL == 0). */
3475 redirect_jump (jump
, nlabel
)
3478 register rtx olabel
= JUMP_LABEL (jump
);
3480 if (nlabel
== olabel
)
3483 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
3486 /* If this is an unconditional branch, delete it from the jump_chain of
3487 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3488 have UID's in range and JUMP_CHAIN is valid). */
3489 if (jump_chain
&& (simplejump_p (jump
)
3490 || GET_CODE (PATTERN (jump
)) == RETURN
))
3492 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
3494 delete_from_jump_chain (jump
);
3495 if (label_index
< max_jump_chain
3496 && INSN_UID (jump
) < max_jump_chain
)
3498 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
3499 jump_chain
[label_index
] = jump
;
3503 JUMP_LABEL (jump
) = nlabel
;
3505 ++LABEL_NUSES (nlabel
);
3507 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
3508 delete_insn (olabel
);
3513 /* Delete the instruction JUMP from any jump chain it might be on. */
3516 delete_from_jump_chain (jump
)
3520 rtx olabel
= JUMP_LABEL (jump
);
3522 /* Handle unconditional jumps. */
3523 if (jump_chain
&& olabel
!= 0
3524 && INSN_UID (olabel
) < max_jump_chain
3525 && simplejump_p (jump
))
3526 index
= INSN_UID (olabel
);
3527 /* Handle return insns. */
3528 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
3532 if (jump_chain
[index
] == jump
)
3533 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
3538 for (insn
= jump_chain
[index
];
3540 insn
= jump_chain
[INSN_UID (insn
)])
3541 if (jump_chain
[INSN_UID (insn
)] == jump
)
3543 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
3549 /* If NLABEL is nonzero, throughout the rtx at LOC,
3550 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3551 zero, alter (RETURN) to (LABEL_REF NLABEL).
3553 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3554 validity with validate_change. Convert (set (pc) (label_ref olabel))
3557 Return 0 if we found a change we would like to make but it is invalid.
3558 Otherwise, return 1. */
3561 redirect_exp (loc
, olabel
, nlabel
, insn
)
3566 register rtx x
= *loc
;
3567 register RTX_CODE code
= GET_CODE (x
);
3571 if (code
== LABEL_REF
)
3573 if (XEXP (x
, 0) == olabel
)
3576 XEXP (x
, 0) = nlabel
;
3578 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3582 else if (code
== RETURN
&& olabel
== 0)
3584 x
= gen_rtx (LABEL_REF
, VOIDmode
, nlabel
);
3585 if (loc
== &PATTERN (insn
))
3586 x
= gen_rtx (SET
, VOIDmode
, pc_rtx
, x
);
3587 return validate_change (insn
, loc
, x
, 0);
3590 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
3591 && GET_CODE (SET_SRC (x
)) == LABEL_REF
3592 && XEXP (SET_SRC (x
), 0) == olabel
)
3593 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3595 fmt
= GET_RTX_FORMAT (code
);
3596 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3599 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
3604 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3605 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
3613 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3615 If the old jump target label (before the dispatch table) becomes unused,
3616 it and the dispatch table may be deleted. In that case, find the insn
3617 before the jump references that label and delete it and logical successors
3621 redirect_tablejump (jump
, nlabel
)
3624 register rtx olabel
= JUMP_LABEL (jump
);
3626 /* Add this jump to the jump_chain of NLABEL. */
3627 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
3628 && INSN_UID (jump
) < max_jump_chain
)
3630 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
3631 jump_chain
[INSN_UID (nlabel
)] = jump
;
3634 PATTERN (jump
) = gen_jump (nlabel
);
3635 JUMP_LABEL (jump
) = nlabel
;
3636 ++LABEL_NUSES (nlabel
);
3637 INSN_CODE (jump
) = -1;
3639 if (--LABEL_NUSES (olabel
) == 0)
3641 delete_labelref_insn (jump
, olabel
, 0);
3642 delete_insn (olabel
);
3646 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3647 If we found one, delete it and then delete this insn if DELETE_THIS is
3648 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3651 delete_labelref_insn (insn
, label
, delete_this
)
3658 if (GET_CODE (insn
) != NOTE
3659 && reg_mentioned_p (label
, PATTERN (insn
)))
3670 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
3671 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
3685 /* Like rtx_equal_p except that it considers two REGs as equal
3686 if they renumber to the same value. */
3689 rtx_renumbered_equal_p (x
, y
)
3693 register RTX_CODE code
= GET_CODE (x
);
3698 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
3699 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
3700 && GET_CODE (SUBREG_REG (y
)) == REG
)))
3704 if (GET_MODE (x
) != GET_MODE (y
))
3707 /* If we haven't done any renumbering, don't
3708 make any assumptions. */
3709 if (reg_renumber
== 0)
3710 return rtx_equal_p (x
, y
);
3714 i
= REGNO (SUBREG_REG (x
));
3715 if (reg_renumber
[i
] >= 0)
3716 i
= reg_renumber
[i
];
3717 i
+= SUBREG_WORD (x
);
3722 if (reg_renumber
[i
] >= 0)
3723 i
= reg_renumber
[i
];
3725 if (GET_CODE (y
) == SUBREG
)
3727 j
= REGNO (SUBREG_REG (y
));
3728 if (reg_renumber
[j
] >= 0)
3729 j
= reg_renumber
[j
];
3730 j
+= SUBREG_WORD (y
);
3735 if (reg_renumber
[j
] >= 0)
3736 j
= reg_renumber
[j
];
3740 /* Now we have disposed of all the cases
3741 in which different rtx codes can match. */
3742 if (code
!= GET_CODE (y
))
3753 return XINT (x
, 0) == XINT (y
, 0);
3756 /* We can't assume nonlocal labels have their following insns yet. */
3757 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
3758 return XEXP (x
, 0) == XEXP (y
, 0);
3759 /* Two label-refs are equivalent if they point at labels
3760 in the same position in the instruction stream. */
3761 return (next_real_insn (XEXP (x
, 0))
3762 == next_real_insn (XEXP (y
, 0)));
3765 return XSTR (x
, 0) == XSTR (y
, 0);
3768 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3770 if (GET_MODE (x
) != GET_MODE (y
))
3773 /* Compare the elements. If any pair of corresponding elements
3774 fail to match, return 0 for the whole things. */
3776 fmt
= GET_RTX_FORMAT (code
);
3777 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3783 if (XWINT (x
, i
) != XWINT (y
, i
))
3788 if (XINT (x
, i
) != XINT (y
, i
))
3793 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
3798 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
3803 if (XEXP (x
, i
) != XEXP (y
, i
))
3810 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
3812 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
3813 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
3824 /* If X is a hard register or equivalent to one or a subregister of one,
3825 return the hard register number. If X is a pseudo register that was not
3826 assigned a hard register, return the pseudo register number. Otherwise,
3827 return -1. Any rtx is valid for X. */
3833 if (GET_CODE (x
) == REG
)
3835 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
3836 return reg_renumber
[REGNO (x
)];
3839 if (GET_CODE (x
) == SUBREG
)
3841 int base
= true_regnum (SUBREG_REG (x
));
3842 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
3843 return SUBREG_WORD (x
) + base
;
3848 /* Optimize code of the form:
3850 for (x = a[i]; x; ...)
3852 for (x = a[i]; x; ...)
3856 Loop optimize will change the above code into
3860 { ...; if (! (x = ...)) break; }
3863 { ...; if (! (x = ...)) break; }
3866 In general, if the first test fails, the program can branch
3867 directly to `foo' and skip the second try which is doomed to fail.
3868 We run this after loop optimization and before flow analysis. */
3870 /* When comparing the insn patterns, we track the fact that different
3871 pseudo-register numbers may have been used in each computation.
3872 The following array stores an equivalence -- same_regs[I] == J means
3873 that pseudo register I was used in the first set of tests in a context
3874 where J was used in the second set. We also count the number of such
3875 pending equivalences. If nonzero, the expressions really aren't the
3878 static int *same_regs
;
3880 static int num_same_regs
;
3882 /* Track any registers modified between the target of the first jump and
3883 the second jump. They never compare equal. */
3885 static char *modified_regs
;
3887 /* Record if memory was modified. */
3889 static int modified_mem
;
3891 /* Called via note_stores on each insn between the target of the first
3892 branch and the second branch. It marks any changed registers. */
3895 mark_modified_reg (dest
, x
)
3901 if (GET_CODE (dest
) == SUBREG
)
3902 dest
= SUBREG_REG (dest
);
3904 if (GET_CODE (dest
) == MEM
)
3907 if (GET_CODE (dest
) != REG
)
3910 regno
= REGNO (dest
);
3911 if (regno
>= FIRST_PSEUDO_REGISTER
)
3912 modified_regs
[regno
] = 1;
3914 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
3915 modified_regs
[regno
+ i
] = 1;
3918 /* F is the first insn in the chain of insns. */
3921 thread_jumps (f
, max_reg
, verbose
)
3926 /* Basic algorithm is to find a conditional branch,
3927 the label it may branch to, and the branch after
3928 that label. If the two branches test the same condition,
3929 walk back from both branch paths until the insn patterns
3930 differ, or code labels are hit. If we make it back to
3931 the target of the first branch, then we know that the first branch
3932 will either always succeed or always fail depending on the relative
3933 senses of the two branches. So adjust the first branch accordingly
3936 rtx label
, b1
, b2
, t1
, t2
;
3937 enum rtx_code code1
, code2
;
3938 rtx b1op0
, b1op1
, b2op0
, b2op1
;
3943 /* Allocate register tables and quick-reset table. */
3944 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
3945 same_regs
= (int *) alloca (max_reg
* sizeof (int));
3946 all_reset
= (int *) alloca (max_reg
* sizeof (int));
3947 for (i
= 0; i
< max_reg
; i
++)
3954 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
3956 /* Get to a candidate branch insn. */
3957 if (GET_CODE (b1
) != JUMP_INSN
3958 || ! condjump_p (b1
) || simplejump_p (b1
)
3959 || JUMP_LABEL (b1
) == 0)
3962 bzero (modified_regs
, max_reg
* sizeof (char));
3965 bcopy (all_reset
, same_regs
, max_reg
* sizeof (int));
3968 label
= JUMP_LABEL (b1
);
3970 /* Look for a branch after the target. Record any registers and
3971 memory modified between the target and the branch. Stop when we
3972 get to a label since we can't know what was changed there. */
3973 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
3975 if (GET_CODE (b2
) == CODE_LABEL
)
3978 else if (GET_CODE (b2
) == JUMP_INSN
)
3980 /* If this is an unconditional jump and is the only use of
3981 its target label, we can follow it. */
3982 if (simplejump_p (b2
)
3983 && JUMP_LABEL (b2
) != 0
3984 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
3986 b2
= JUMP_LABEL (b2
);
3993 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
3996 if (GET_CODE (b2
) == CALL_INSN
)
3999 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
4000 if (call_used_regs
[i
] && ! fixed_regs
[i
]
4001 && i
!= STACK_POINTER_REGNUM
4002 && i
!= FRAME_POINTER_REGNUM
4003 && i
!= ARG_POINTER_REGNUM
)
4004 modified_regs
[i
] = 1;
4007 note_stores (PATTERN (b2
), mark_modified_reg
);
4010 /* Check the next candidate branch insn from the label
4013 || GET_CODE (b2
) != JUMP_INSN
4015 || ! condjump_p (b2
)
4016 || simplejump_p (b2
))
4019 /* Get the comparison codes and operands, reversing the
4020 codes if appropriate. If we don't have comparison codes,
4021 we can't do anything. */
4022 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
4023 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
4024 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
4025 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
4026 code1
= reverse_condition (code1
);
4028 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
4029 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
4030 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
4031 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
4032 code2
= reverse_condition (code2
);
4034 /* If they test the same things and knowing that B1 branches
4035 tells us whether or not B2 branches, check if we
4036 can thread the branch. */
4037 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
4038 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
4039 && (comparison_dominates_p (code1
, code2
)
4040 || comparison_dominates_p (code1
, reverse_condition (code2
))))
4042 t1
= prev_nonnote_insn (b1
);
4043 t2
= prev_nonnote_insn (b2
);
4045 while (t1
!= 0 && t2
!= 0)
4047 if (t1
== 0 || t2
== 0)
4052 /* We have reached the target of the first branch.
4053 If there are no pending register equivalents,
4054 we know that this branch will either always
4055 succeed (if the senses of the two branches are
4056 the same) or always fail (if not). */
4059 if (num_same_regs
!= 0)
4062 if (comparison_dominates_p (code1
, code2
))
4063 new_label
= JUMP_LABEL (b2
);
4065 new_label
= get_label_after (b2
);
4067 if (JUMP_LABEL (b1
) != new_label
4068 && redirect_jump (b1
, new_label
))
4073 /* If either of these is not a normal insn (it might be
4074 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4075 have already been skipped above.) Similarly, fail
4076 if the insns are different. */
4077 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
4078 || recog_memoized (t1
) != recog_memoized (t2
)
4079 || ! rtx_equal_for_thread_p (PATTERN (t1
),
4083 t1
= prev_nonnote_insn (t1
);
4084 t2
= prev_nonnote_insn (t2
);
4091 /* This is like RTX_EQUAL_P except that it knows about our handling of
4092 possibly equivalent registers and knows to consider volatile and
4093 modified objects as not equal.
4095 YINSN is the insn containing Y. */
4098 rtx_equal_for_thread_p (x
, y
, yinsn
)
4104 register enum rtx_code code
;
4107 code
= GET_CODE (x
);
4108 /* Rtx's of different codes cannot be equal. */
4109 if (code
!= GET_CODE (y
))
4112 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4113 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4115 if (GET_MODE (x
) != GET_MODE (y
))
4118 /* Handle special-cases first. */
4122 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
4125 /* If neither is user variable or hard register, check for possible
4127 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
4128 || REGNO (x
) < FIRST_PSEUDO_REGISTER
4129 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
4132 if (same_regs
[REGNO (x
)] == -1)
4134 same_regs
[REGNO (x
)] = REGNO (y
);
4137 /* If this is the first time we are seeing a register on the `Y'
4138 side, see if it is the last use. If not, we can't thread the
4139 jump, so mark it as not equivalent. */
4140 if (regno_last_uid
[REGNO (y
)] != INSN_UID (yinsn
))
4146 return (same_regs
[REGNO (x
)] == REGNO (y
));
4151 /* If memory modified or either volatile, not equivalent.
4152 Else, check address. */
4153 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4156 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4159 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4165 /* Cancel a pending `same_regs' if setting equivalenced registers.
4166 Then process source. */
4167 if (GET_CODE (SET_DEST (x
)) == REG
4168 && GET_CODE (SET_DEST (y
)) == REG
)
4170 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
4172 same_regs
[REGNO (SET_DEST (x
))] = -1;
4175 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
4179 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
4182 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
4185 return XEXP (x
, 0) == XEXP (y
, 0);
4188 return XSTR (x
, 0) == XSTR (y
, 0);
4194 fmt
= GET_RTX_FORMAT (code
);
4195 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4200 if (XWINT (x
, i
) != XWINT (y
, i
))
4206 if (XINT (x
, i
) != XINT (y
, i
))
4212 /* Two vectors must have the same length. */
4213 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4216 /* And the corresponding elements must match. */
4217 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4218 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
4219 XVECEXP (y
, i
, j
), yinsn
) == 0)
4224 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
4230 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4235 /* These are just backpointers, so they don't matter. */
4241 /* It is believed that rtx's at this level will never
4242 contain anything but integers and other rtx's,
4243 except for within LABEL_REFs and SYMBOL_REFs. */