1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992 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 (SET_DEST (pbody
))
350 > stack_adjust_amount
)
352 total_pushed
+= GET_MODE_SIZE (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 (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))
624 && GET_CODE (dispatch
) == JUMP_INSN
625 && JUMP_LABEL (dispatch
) != 0
626 /* Don't mess with a casesi insn. */
627 && !(GET_CODE (PATTERN (dispatch
)) == SET
628 && (GET_CODE (SET_SRC (PATTERN (dispatch
)))
630 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
632 redirect_tablejump (dispatch
,
633 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
638 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
640 /* If a jump references the end of the function, try to turn
641 it into a RETURN insn, possibly a conditional one. */
642 if (JUMP_LABEL (insn
)
643 && next_active_insn (JUMP_LABEL (insn
)) == 0)
644 changed
|= redirect_jump (insn
, NULL_RTX
);
646 /* Detect jump to following insn. */
647 if (reallabelprev
== insn
&& condjump_p (insn
))
654 /* If we have an unconditional jump preceded by a USE, try to put
655 the USE before the target and jump there. This simplifies many
656 of the optimizations below since we don't have to worry about
657 dealing with these USE insns. We only do this if the label
658 being branch to already has the identical USE or if code
659 never falls through to that label. */
661 if (this_is_simplejump
662 && (temp
= prev_nonnote_insn (insn
)) != 0
663 && GET_CODE (temp
) == INSN
&& GET_CODE (PATTERN (temp
)) == USE
664 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
665 && (GET_CODE (temp1
) == BARRIER
666 || (GET_CODE (temp1
) == INSN
667 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
)))))
669 if (GET_CODE (temp1
) == BARRIER
)
671 emit_insn_after (PATTERN (temp
), temp1
);
672 temp1
= NEXT_INSN (temp1
);
676 redirect_jump (insn
, get_label_before (temp1
));
677 reallabelprev
= prev_real_insn (temp1
);
681 /* Simplify if (...) x = a; else x = b; by converting it
682 to x = b; if (...) x = a;
683 if B is sufficiently simple, the test doesn't involve X,
684 and nothing in the test modifies B or X.
686 If we have small register classes, we also can't do this if X
689 If the "x = b;" insn has any REG_NOTES, we don't do this because
690 of the possibility that we are running after CSE and there is a
691 REG_EQUAL note that is only valid if the branch has already been
692 taken. If we move the insn with the REG_EQUAL note, we may
693 fold the comparison to always be false in a later CSE pass.
694 (We could also delete the REG_NOTES when moving the insn, but it
695 seems simpler to not move it.) An exception is that we can move
696 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
697 value is the same as "b".
699 INSN is the branch over the `else' part.
703 TEMP to the jump insn preceding "x = a;"
705 TEMP2 to the insn that sets "x = b;"
706 TEMP3 to the insn that sets "x = a;"
707 TEMP4 to the set of "x = b"; */
709 if (this_is_simplejump
710 && (temp3
= prev_active_insn (insn
)) != 0
711 && GET_CODE (temp3
) == INSN
712 && (temp4
= single_set (temp3
)) != 0
713 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
714 #ifdef SMALL_REGISTER_CLASSES
715 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
717 && (temp2
= next_active_insn (insn
)) != 0
718 && GET_CODE (temp2
) == INSN
719 && (temp4
= single_set (temp2
)) != 0
720 && rtx_equal_p (SET_DEST (temp4
), temp1
)
721 && (GET_CODE (SET_SRC (temp4
)) == REG
722 || GET_CODE (SET_SRC (temp4
)) == SUBREG
723 || CONSTANT_P (SET_SRC (temp4
)))
724 && (REG_NOTES (temp2
) == 0
725 || ((REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUAL
726 || REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUIV
)
727 && XEXP (REG_NOTES (temp2
), 1) == 0
728 && rtx_equal_p (XEXP (REG_NOTES (temp2
), 0),
730 && (temp
= prev_active_insn (temp3
)) != 0
731 && condjump_p (temp
) && ! simplejump_p (temp
)
732 /* TEMP must skip over the "x = a;" insn */
733 && prev_real_insn (JUMP_LABEL (temp
)) == insn
734 && no_labels_between_p (insn
, JUMP_LABEL (temp
))
735 /* There must be no other entries to the "x = b;" insn. */
736 && no_labels_between_p (JUMP_LABEL (temp
), temp2
)
737 /* INSN must either branch to the insn after TEMP2 or the insn
738 after TEMP2 must branch to the same place as INSN. */
739 && (reallabelprev
== temp2
740 || ((temp5
= next_active_insn (temp2
)) != 0
741 && simplejump_p (temp5
)
742 && JUMP_LABEL (temp5
) == JUMP_LABEL (insn
))))
744 /* The test expression, X, may be a complicated test with
745 multiple branches. See if we can find all the uses of
746 the label that TEMP branches to without hitting a CALL_INSN
747 or a jump to somewhere else. */
748 rtx target
= JUMP_LABEL (temp
);
749 int nuses
= LABEL_NUSES (target
);
752 /* Set P to the first jump insn that goes around "x = a;". */
753 for (p
= temp
; nuses
&& p
; p
= prev_nonnote_insn (p
))
755 if (GET_CODE (p
) == JUMP_INSN
)
757 if (condjump_p (p
) && ! simplejump_p (p
)
758 && JUMP_LABEL (p
) == target
)
767 else if (GET_CODE (p
) == CALL_INSN
)
772 /* We cannot insert anything between a set of cc and its use
773 so if P uses cc0, we must back up to the previous insn. */
774 q
= prev_nonnote_insn (p
);
775 if (q
&& GET_RTX_CLASS (GET_CODE (q
)) == 'i'
776 && sets_cc0_p (PATTERN (q
)))
783 /* If we found all the uses and there was no data conflict, we
784 can move the assignment unless we can branch into the middle
787 && no_labels_between_p (p
, insn
)
788 && ! reg_referenced_between_p (temp1
, p
, NEXT_INSN (temp3
))
789 && ! reg_set_between_p (temp1
, p
, temp3
)
790 && (GET_CODE (SET_SRC (temp4
)) == CONST_INT
791 || ! reg_set_between_p (SET_SRC (temp4
), p
, temp2
)))
793 emit_insn_after_with_line_notes (PATTERN (temp2
), p
, temp2
);
796 /* Set NEXT to an insn that we know won't go away. */
797 next
= next_active_insn (insn
);
799 /* Delete the jump around the set. Note that we must do
800 this before we redirect the test jumps so that it won't
801 delete the code immediately following the assignment
802 we moved (which might be a jump). */
806 /* We either have two consecutive labels or a jump to
807 a jump, so adjust all the JUMP_INSNs to branch to where
809 for (p
= NEXT_INSN (p
); p
!= next
; p
= NEXT_INSN (p
))
810 if (GET_CODE (p
) == JUMP_INSN
)
811 redirect_jump (p
, target
);
819 /* If we have if (...) x = exp; and branches are expensive,
820 EXP is a single insn, does not have any side effects, cannot
821 trap, and is not too costly, convert this to
822 t = exp; if (...) x = t;
824 Don't do this when we have CC0 because it is unlikely to help
825 and we'd need to worry about where to place the new insn and
826 the potential for conflicts. We also can't do this when we have
827 notes on the insn for the same reason as above.
831 TEMP to the "x = exp;" insn.
832 TEMP1 to the single set in the "x = exp; insn.
835 if (! reload_completed
836 && this_is_condjump
&& ! this_is_simplejump
838 && (temp
= next_nonnote_insn (insn
)) != 0
839 && REG_NOTES (temp
) == 0
840 && (reallabelprev
== temp
841 || ((temp2
= next_active_insn (temp
)) != 0
842 && simplejump_p (temp2
)
843 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
844 && (temp1
= single_set (temp
)) != 0
845 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
846 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
847 #ifdef SMALL_REGISTER_CLASSES
848 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
850 && GET_CODE (SET_SRC (temp1
)) != REG
851 && GET_CODE (SET_SRC (temp1
)) != SUBREG
852 && GET_CODE (SET_SRC (temp1
)) != CONST_INT
853 && ! side_effects_p (SET_SRC (temp1
))
854 && ! may_trap_p (SET_SRC (temp1
))
855 && rtx_cost (SET_SRC (temp1
)) < 10)
857 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
859 if (validate_change (temp
, &SET_DEST (temp1
), new, 0))
861 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
862 emit_insn_after_with_line_notes (PATTERN (temp
),
863 PREV_INSN (insn
), temp
);
868 /* Similarly, if it takes two insns to compute EXP but they
869 have the same destination. Here TEMP3 will be the second
870 insn and TEMP4 the SET from that insn. */
872 if (! reload_completed
873 && this_is_condjump
&& ! this_is_simplejump
875 && (temp
= next_nonnote_insn (insn
)) != 0
876 && REG_NOTES (temp
) == 0
877 && (temp3
= next_nonnote_insn (temp
)) != 0
878 && REG_NOTES (temp3
) == 0
879 && (reallabelprev
== temp3
880 || ((temp2
= next_active_insn (temp3
)) != 0
881 && simplejump_p (temp2
)
882 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
883 && (temp1
= single_set (temp
)) != 0
884 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
885 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
886 #ifdef SMALL_REGISTER_CLASSES
887 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
889 && ! side_effects_p (SET_SRC (temp1
))
890 && ! may_trap_p (SET_SRC (temp1
))
891 && rtx_cost (SET_SRC (temp1
)) < 10
892 && (temp4
= single_set (temp3
)) != 0
893 && rtx_equal_p (SET_DEST (temp4
), temp2
)
894 && ! side_effects_p (SET_SRC (temp4
))
895 && ! may_trap_p (SET_SRC (temp4
))
896 && rtx_cost (SET_SRC (temp4
)) < 10)
898 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
900 if (validate_change (temp
, &SET_DEST (temp1
), new, 0))
902 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
903 emit_insn_after_with_line_notes (PATTERN (temp
),
904 PREV_INSN (insn
), temp
);
905 emit_insn_after_with_line_notes
906 (replace_rtx (PATTERN (temp3
), temp2
, new),
907 PREV_INSN (insn
), temp3
);
913 /* Finally, handle the case where two insns are used to
914 compute EXP but a temporary register is used. Here we must
915 ensure that the temporary register is not used anywhere else. */
917 if (! reload_completed
919 && this_is_condjump
&& ! this_is_simplejump
921 && (temp
= next_nonnote_insn (insn
)) != 0
922 && REG_NOTES (temp
) == 0
923 && (temp3
= next_nonnote_insn (temp
)) != 0
924 && REG_NOTES (temp3
) == 0
925 && (reallabelprev
== temp3
926 || ((temp2
= next_active_insn (temp3
)) != 0
927 && simplejump_p (temp2
)
928 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
929 && (temp1
= single_set (temp
)) != 0
930 && (temp5
= SET_DEST (temp1
), GET_CODE (temp5
) == REG
)
931 && REGNO (temp5
) >= FIRST_PSEUDO_REGISTER
932 && regno_first_uid
[REGNO (temp5
)] == INSN_UID (temp
)
933 && regno_last_uid
[REGNO (temp5
)] == INSN_UID (temp3
)
934 && ! side_effects_p (SET_SRC (temp1
))
935 && ! may_trap_p (SET_SRC (temp1
))
936 && rtx_cost (SET_SRC (temp1
)) < 10
937 && (temp4
= single_set (temp3
)) != 0
938 && (temp2
= SET_DEST (temp4
), GET_CODE (temp2
) == REG
)
939 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
940 #ifdef SMALL_REGISTER_CLASSES
941 && REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
943 && rtx_equal_p (SET_DEST (temp4
), temp2
)
944 && ! side_effects_p (SET_SRC (temp4
))
945 && ! may_trap_p (SET_SRC (temp4
))
946 && rtx_cost (SET_SRC (temp4
)) < 10)
948 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
950 if (validate_change (temp3
, &SET_DEST (temp4
), new, 0))
952 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
953 emit_insn_after_with_line_notes (PATTERN (temp
),
954 PREV_INSN (insn
), temp
);
955 emit_insn_after_with_line_notes (PATTERN (temp3
),
956 PREV_INSN (insn
), temp3
);
961 #endif /* HAVE_cc0 */
963 /* We deal with four cases:
965 1) x = a; if (...) x = b; and either A or B is zero,
966 2) if (...) x = 0; and jumps are expensive,
967 3) x = a; if (...) x = b; and A and B are constants where all the
968 set bits in A are also set in B and jumps are expensive, and
969 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
971 5) if (...) x = b; if jumps are even more expensive.
973 In each of these try to use a store-flag insn to avoid the jump.
974 (If the jump would be faster, the machine should not have
975 defined the scc insns!). These cases are often made by the
976 previous optimization.
978 INSN here is the jump around the store. We set:
980 TEMP to the "x = b;" insn.
982 TEMP2 to B (const0_rtx in the second case).
983 TEMP3 to A (X in the second case).
984 TEMP4 to the condition being tested.
985 TEMP5 to the earliest insn used to find the condition. */
987 if (/* We can't do this after reload has completed. */
989 && this_is_condjump
&& ! this_is_simplejump
990 /* Set TEMP to the "x = b;" insn. */
991 && (temp
= next_nonnote_insn (insn
)) != 0
992 && GET_CODE (temp
) == INSN
993 && GET_CODE (PATTERN (temp
)) == SET
994 && GET_CODE (temp1
= SET_DEST (PATTERN (temp
))) == REG
995 #ifdef SMALL_REGISTER_CLASSES
996 && REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
998 && GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
999 && (GET_CODE (temp2
= SET_SRC (PATTERN (temp
))) == REG
1000 || GET_CODE (temp2
) == SUBREG
1001 || GET_CODE (temp2
) == CONST_INT
)
1002 /* Allow either form, but prefer the former if both apply.
1003 There is no point in using the old value of TEMP1 if
1004 it is a register, since cse will alias them. It can
1005 lose if the old value were a hard register since CSE
1006 won't replace hard registers. */
1007 && (((temp3
= reg_set_last (temp1
, insn
)) != 0
1008 && GET_CODE (temp3
) == CONST_INT
)
1009 /* Make the latter case look like x = x; if (...) x = 0; */
1012 && temp2
== const0_rtx
)
1013 || BRANCH_COST
>= 3)))
1014 /* INSN must either branch to the insn after TEMP or the insn
1015 after TEMP must branch to the same place as INSN. */
1016 && (reallabelprev
== temp
1017 || ((temp4
= next_active_insn (temp
)) != 0
1018 && simplejump_p (temp4
)
1019 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
1020 && (temp4
= get_condition (insn
, &temp5
)) != 0
1022 /* If B is zero, OK; if A is zero, can only do (1) if we
1023 can reverse the condition. See if (3) applies possibly
1024 by reversing the condition. Prefer reversing to (4) when
1025 branches are very expensive. */
1026 && ((reversep
= 0, temp2
== const0_rtx
)
1027 || (temp3
== const0_rtx
1028 && (reversep
= can_reverse_comparison_p (temp4
, insn
)))
1029 || (BRANCH_COST
>= 2
1030 && GET_CODE (temp2
) == CONST_INT
1031 && GET_CODE (temp3
) == CONST_INT
1032 && ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp2
)
1033 || ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp3
)
1034 && (reversep
= can_reverse_comparison_p (temp4
,
1036 || BRANCH_COST
>= 3)
1038 /* If the previous insn sets CC0 and something else, we can't
1039 do this since we are going to delete that insn. */
1041 && ! ((temp6
= prev_nonnote_insn (insn
)) != 0
1042 && GET_CODE (temp6
) == INSN
1043 && (sets_cc0_p (PATTERN (temp6
)) == -1
1044 || (sets_cc0_p (PATTERN (temp6
)) == 1
1045 && FIND_REG_INC_NOTE (temp6
, NULL_RTX
))))
1049 enum rtx_code code
= GET_CODE (temp4
);
1050 rtx uval
, cval
, var
= temp1
;
1054 /* If necessary, reverse the condition. */
1056 code
= reverse_condition (code
), uval
= temp2
, cval
= temp3
;
1058 uval
= temp3
, cval
= temp2
;
1060 /* See if we can do this with a store-flag insn. */
1063 /* If CVAL is non-zero, normalize to -1. Otherwise,
1064 if UVAL is the constant 1, it is best to just compute
1065 the result directly. If UVAL is constant and STORE_FLAG_VALUE
1066 includes all of its bits, it is best to compute the flag
1067 value unnormalized and `and' it with UVAL. Otherwise,
1068 normalize to -1 and `and' with UVAL. */
1069 normalizep
= (cval
!= const0_rtx
? -1
1070 : (uval
== const1_rtx
? 1
1071 : (GET_CODE (uval
) == CONST_INT
1072 && (INTVAL (uval
) & ~STORE_FLAG_VALUE
) == 0)
1075 /* We will be putting the store-flag insn immediately in
1076 front of the comparison that was originally being done,
1077 so we know all the variables in TEMP4 will be valid.
1078 However, this might be in front of the assignment of
1079 A to VAR. If it is, it would clobber the store-flag
1080 we will be emitting.
1082 Therefore, emit into a temporary which will be copied to
1083 VAR immediately after TEMP. */
1085 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
1086 XEXP (temp4
, 0), XEXP (temp4
, 1),
1088 (code
== LTU
|| code
== LEU
1089 || code
== GEU
|| code
== GTU
),
1096 /* Put the store-flag insns in front of the first insn
1097 used to compute the condition to ensure that we
1098 use the same values of them as the current
1099 comparison. However, the remainder of the insns we
1100 generate will be placed directly in front of the
1101 jump insn, in case any of the pseudos we use
1102 are modified earlier. */
1107 emit_insns_before (seq
, temp5
);
1111 /* Both CVAL and UVAL are non-zero. */
1112 if (cval
!= const0_rtx
&& uval
!= const0_rtx
)
1116 tem1
= expand_and (uval
, target
, NULL_RTX
);
1117 if (GET_CODE (cval
) == CONST_INT
1118 && GET_CODE (uval
) == CONST_INT
1119 && (INTVAL (cval
) & INTVAL (uval
)) == INTVAL (cval
))
1123 tem2
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1124 target
, NULL_RTX
, 0);
1125 tem2
= expand_and (cval
, tem2
, tem2
);
1128 /* If we usually make new pseudos, do so here. This
1129 turns out to help machines that have conditional
1132 if (flag_expensive_optimizations
)
1135 target
= expand_binop (GET_MODE (var
), ior_optab
,
1139 else if (normalizep
!= 1)
1140 target
= expand_and (uval
, target
,
1141 (GET_CODE (target
) == REG
1142 && ! preserve_subexpressions_p ()
1143 ? target
: NULL_RTX
));
1145 emit_move_insn (var
, target
);
1150 /* If INSN uses CC0, we must not separate it from the
1151 insn that sets cc0. */
1153 if (reg_mentioned_p (cc0_rtx
, PATTERN (before
)))
1154 before
= prev_nonnote_insn (before
);
1157 emit_insns_before (seq
, before
);
1160 next
= NEXT_INSN (insn
);
1170 /* If branches are expensive, convert
1171 if (foo) bar++; to bar += (foo != 0);
1172 and similarly for "bar--;"
1174 INSN is the conditional branch around the arithmetic. We set:
1176 TEMP is the arithmetic insn.
1177 TEMP1 is the SET doing the arithmetic.
1178 TEMP2 is the operand being incremented or decremented.
1179 TEMP3 to the condition being tested.
1180 TEMP4 to the earliest insn used to find the condition. */
1182 if (BRANCH_COST
>= 2
1183 && ! reload_completed
1184 && this_is_condjump
&& ! this_is_simplejump
1185 && (temp
= next_nonnote_insn (insn
)) != 0
1186 && (temp1
= single_set (temp
)) != 0
1187 && (temp2
= SET_DEST (temp1
),
1188 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
1189 && GET_CODE (SET_SRC (temp1
)) == PLUS
1190 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1191 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
1192 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
1193 /* INSN must either branch to the insn after TEMP or the insn
1194 after TEMP must branch to the same place as INSN. */
1195 && (reallabelprev
== temp
1196 || ((temp3
= next_active_insn (temp
)) != 0
1197 && simplejump_p (temp3
)
1198 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
1199 && (temp3
= get_condition (insn
, &temp4
)) != 0
1200 && can_reverse_comparison_p (temp3
, insn
))
1202 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
1203 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
1207 /* It must be the case that TEMP2 is not modified in the range
1208 [TEMP4, INSN). The one exception we make is if the insn
1209 before INSN sets TEMP2 to something which is also unchanged
1210 in that range. In that case, we can move the initialization
1211 into our sequence. */
1213 if ((temp5
= prev_active_insn (insn
)) != 0
1214 && GET_CODE (temp5
) == INSN
1215 && (temp6
= single_set (temp5
)) != 0
1216 && rtx_equal_p (temp2
, SET_DEST (temp6
))
1217 && (CONSTANT_P (SET_SRC (temp6
))
1218 || GET_CODE (SET_SRC (temp6
)) == REG
1219 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
1221 emit_insn (PATTERN (temp5
));
1223 init
= SET_SRC (temp6
);
1226 if (CONSTANT_P (init
)
1227 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
1228 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
1229 XEXP (temp3
, 0), XEXP (temp3
, 1),
1231 (code
== LTU
|| code
== LEU
1232 || code
== GTU
|| code
== GEU
), 1);
1234 /* If we can do the store-flag, do the addition or
1238 target
= expand_binop (GET_MODE (temp2
),
1239 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1240 ? add_optab
: sub_optab
),
1241 temp2
, target
, temp2
, OPTAB_WIDEN
);
1245 /* Put the result back in temp2 in case it isn't already.
1246 Then replace the jump, possible a CC0-setting insn in
1247 front of the jump, and TEMP, with the sequence we have
1250 if (target
!= temp2
)
1251 emit_move_insn (temp2
, target
);
1256 emit_insns_before (seq
, temp4
);
1260 delete_insn (init_insn
);
1262 next
= NEXT_INSN (insn
);
1264 delete_insn (prev_nonnote_insn (insn
));
1274 /* Simplify if (...) x = 1; else {...} if (x) ...
1275 We recognize this case scanning backwards as well.
1277 TEMP is the assignment to x;
1278 TEMP1 is the label at the head of the second if. */
1279 /* ?? This should call get_condition to find the values being
1280 compared, instead of looking for a COMPARE insn when HAVE_cc0
1281 is not defined. This would allow it to work on the m88k. */
1282 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1283 is not defined and the condition is tested by a separate compare
1284 insn. This is because the code below assumes that the result
1285 of the compare dies in the following branch.
1287 Not only that, but there might be other insns between the
1288 compare and branch whose results are live. Those insns need
1291 A way to fix this is to move the insns at JUMP_LABEL (insn)
1292 to before INSN. If we are running before flow, they will
1293 be deleted if they aren't needed. But this doesn't work
1296 This is really a special-case of jump threading, anyway. The
1297 right thing to do is to replace this and jump threading with
1298 much simpler code in cse.
1300 This code has been turned off in the non-cc0 case in the
1304 else if (this_is_simplejump
1305 /* Safe to skip USE and CLOBBER insns here
1306 since they will not be deleted. */
1307 && (temp
= prev_active_insn (insn
))
1308 && no_labels_between_p (temp
, insn
)
1309 && GET_CODE (temp
) == INSN
1310 && GET_CODE (PATTERN (temp
)) == SET
1311 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1312 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1313 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1314 /* If we find that the next value tested is `x'
1315 (TEMP1 is the insn where this happens), win. */
1316 && GET_CODE (temp1
) == INSN
1317 && GET_CODE (PATTERN (temp1
)) == SET
1319 /* Does temp1 `tst' the value of x? */
1320 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1321 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1322 && (temp1
= next_nonnote_insn (temp1
))
1324 /* Does temp1 compare the value of x against zero? */
1325 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1326 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1327 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1328 == SET_DEST (PATTERN (temp
)))
1329 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1330 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1332 && condjump_p (temp1
))
1334 /* Get the if_then_else from the condjump. */
1335 rtx choice
= SET_SRC (PATTERN (temp1
));
1336 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1338 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1339 rtx val
= SET_SRC (PATTERN (temp
));
1341 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1345 if (cond
== const_true_rtx
)
1346 ultimate
= XEXP (choice
, 1);
1347 else if (cond
== const0_rtx
)
1348 ultimate
= XEXP (choice
, 2);
1352 if (ultimate
== pc_rtx
)
1353 ultimate
= get_label_after (temp1
);
1354 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1355 ultimate
= XEXP (ultimate
, 0);
1358 changed
|= redirect_jump (insn
, ultimate
);
1364 /* @@ This needs a bit of work before it will be right.
1366 Any type of comparison can be accepted for the first and
1367 second compare. When rewriting the first jump, we must
1368 compute the what conditions can reach label3, and use the
1369 appropriate code. We can not simply reverse/swap the code
1370 of the first jump. In some cases, the second jump must be
1374 < == converts to > ==
1375 < != converts to == >
1378 If the code is written to only accept an '==' test for the second
1379 compare, then all that needs to be done is to swap the condition
1380 of the first branch.
1382 It is questionable whether we want this optimization anyways,
1383 since if the user wrote code like this because he/she knew that
1384 the jump to label1 is taken most of the time, then rewriting
1385 this gives slower code. */
1386 /* @@ This should call get_condition to find the values being
1387 compared, instead of looking for a COMPARE insn when HAVE_cc0
1388 is not defined. This would allow it to work on the m88k. */
1389 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1390 is not defined and the condition is tested by a separate compare
1391 insn. This is because the code below assumes that the result
1392 of the compare dies in the following branch. */
1394 /* Simplify test a ~= b
1408 where ~= is an inequality, e.g. >, and ~~= is the swapped
1411 We recognize this case scanning backwards.
1413 TEMP is the conditional jump to `label2';
1414 TEMP1 is the test for `a == b';
1415 TEMP2 is the conditional jump to `label1';
1416 TEMP3 is the test for `a ~= b'. */
1417 else if (this_is_simplejump
1418 && (temp
= prev_active_insn (insn
))
1419 && no_labels_between_p (temp
, insn
)
1420 && condjump_p (temp
)
1421 && (temp1
= prev_active_insn (temp
))
1422 && no_labels_between_p (temp1
, temp
)
1423 && GET_CODE (temp1
) == INSN
1424 && GET_CODE (PATTERN (temp1
)) == SET
1426 && sets_cc0_p (PATTERN (temp1
)) == 1
1428 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1429 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1430 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1432 && (temp2
= prev_active_insn (temp1
))
1433 && no_labels_between_p (temp2
, temp1
)
1434 && condjump_p (temp2
)
1435 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1436 && (temp3
= prev_active_insn (temp2
))
1437 && no_labels_between_p (temp3
, temp2
)
1438 && GET_CODE (PATTERN (temp3
)) == SET
1439 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1440 SET_DEST (PATTERN (temp1
)))
1441 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1442 SET_SRC (PATTERN (temp3
)))
1443 && ! inequality_comparisons_p (PATTERN (temp
))
1444 && inequality_comparisons_p (PATTERN (temp2
)))
1446 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1448 ++LABEL_NUSES (fallthrough_label
);
1449 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1455 if (--LABEL_NUSES (fallthrough_label
) == 0)
1456 delete_insn (fallthrough_label
);
1459 /* Simplify if (...) {... x = 1;} if (x) ...
1461 We recognize this case backwards.
1463 TEMP is the test of `x';
1464 TEMP1 is the assignment to `x' at the end of the
1465 previous statement. */
1466 /* @@ This should call get_condition to find the values being
1467 compared, instead of looking for a COMPARE insn when HAVE_cc0
1468 is not defined. This would allow it to work on the m88k. */
1469 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1470 is not defined and the condition is tested by a separate compare
1471 insn. This is because the code below assumes that the result
1472 of the compare dies in the following branch. */
1474 /* ??? This has to be turned off. The problem is that the
1475 unconditional jump might indirectly end up branching to the
1476 label between TEMP1 and TEMP. We can't detect this, in general,
1477 since it may become a jump to there after further optimizations.
1478 If that jump is done, it will be deleted, so we will retry
1479 this optimization in the next pass, thus an infinite loop.
1481 The present code prevents this by putting the jump after the
1482 label, but this is not logically correct. */
1484 else if (this_is_condjump
1485 /* Safe to skip USE and CLOBBER insns here
1486 since they will not be deleted. */
1487 && (temp
= prev_active_insn (insn
))
1488 && no_labels_between_p (temp
, insn
)
1489 && GET_CODE (temp
) == INSN
1490 && GET_CODE (PATTERN (temp
)) == SET
1492 && sets_cc0_p (PATTERN (temp
)) == 1
1493 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1495 /* Temp must be a compare insn, we can not accept a register
1496 to register move here, since it may not be simply a
1498 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1499 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1500 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1501 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1502 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1504 /* May skip USE or CLOBBER insns here
1505 for checking for opportunity, since we
1506 take care of them later. */
1507 && (temp1
= prev_active_insn (temp
))
1508 && GET_CODE (temp1
) == INSN
1509 && GET_CODE (PATTERN (temp1
)) == SET
1511 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1513 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1514 == SET_DEST (PATTERN (temp1
)))
1516 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1517 /* If this isn't true, cse will do the job. */
1518 && ! no_labels_between_p (temp1
, temp
))
1520 /* Get the if_then_else from the condjump. */
1521 rtx choice
= SET_SRC (PATTERN (insn
));
1522 if (GET_CODE (choice
) == IF_THEN_ELSE
1523 && (GET_CODE (XEXP (choice
, 0)) == EQ
1524 || GET_CODE (XEXP (choice
, 0)) == NE
))
1526 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1531 /* Get the place that condjump will jump to
1532 if it is reached from here. */
1533 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1535 ultimate
= XEXP (choice
, 1);
1537 ultimate
= XEXP (choice
, 2);
1538 /* Get it as a CODE_LABEL. */
1539 if (ultimate
== pc_rtx
)
1540 ultimate
= get_label_after (insn
);
1542 /* Get the label out of the LABEL_REF. */
1543 ultimate
= XEXP (ultimate
, 0);
1545 /* Insert the jump immediately before TEMP, specifically
1546 after the label that is between TEMP1 and TEMP. */
1547 last_insn
= PREV_INSN (temp
);
1549 /* If we would be branching to the next insn, the jump
1550 would immediately be deleted and the re-inserted in
1551 a subsequent pass over the code. So don't do anything
1553 if (next_active_insn (last_insn
)
1554 != next_active_insn (ultimate
))
1556 emit_barrier_after (last_insn
);
1557 p
= emit_jump_insn_after (gen_jump (ultimate
),
1559 JUMP_LABEL (p
) = ultimate
;
1560 ++LABEL_NUSES (ultimate
);
1561 if (INSN_UID (ultimate
) < max_jump_chain
1562 && INSN_CODE (p
) < max_jump_chain
)
1564 jump_chain
[INSN_UID (p
)]
1565 = jump_chain
[INSN_UID (ultimate
)];
1566 jump_chain
[INSN_UID (ultimate
)] = p
;
1574 /* Detect a conditional jump going to the same place
1575 as an immediately following unconditional jump. */
1576 else if (this_is_condjump
1577 && (temp
= next_active_insn (insn
)) != 0
1578 && simplejump_p (temp
)
1579 && (next_active_insn (JUMP_LABEL (insn
))
1580 == next_active_insn (JUMP_LABEL (temp
))))
1586 /* Detect a conditional jump jumping over an unconditional jump. */
1588 else if (this_is_condjump
&& ! this_is_simplejump
1589 && reallabelprev
!= 0
1590 && GET_CODE (reallabelprev
) == JUMP_INSN
1591 && prev_active_insn (reallabelprev
) == insn
1592 && no_labels_between_p (insn
, reallabelprev
)
1593 && simplejump_p (reallabelprev
))
1595 /* When we invert the unconditional jump, we will be
1596 decrementing the usage count of its old label.
1597 Make sure that we don't delete it now because that
1598 might cause the following code to be deleted. */
1599 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
1600 rtx prev_label
= JUMP_LABEL (insn
);
1602 ++LABEL_NUSES (prev_label
);
1604 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
1606 /* It is very likely that if there are USE insns before
1607 this jump, they hold REG_DEAD notes. These REG_DEAD
1608 notes are no longer valid due to this optimization,
1609 and will cause the life-analysis that following passes
1610 (notably delayed-branch scheduling) to think that
1611 these registers are dead when they are not.
1613 To prevent this trouble, we just remove the USE insns
1614 from the insn chain. */
1616 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
1617 && GET_CODE (PATTERN (prev_uses
)) == USE
)
1619 rtx useless
= prev_uses
;
1620 prev_uses
= prev_nonnote_insn (prev_uses
);
1621 delete_insn (useless
);
1624 delete_insn (reallabelprev
);
1629 /* We can now safely delete the label if it is unreferenced
1630 since the delete_insn above has deleted the BARRIER. */
1631 if (--LABEL_NUSES (prev_label
) == 0)
1632 delete_insn (prev_label
);
1637 /* Detect a jump to a jump. */
1639 nlabel
= follow_jumps (JUMP_LABEL (insn
));
1640 if (nlabel
!= JUMP_LABEL (insn
)
1641 && redirect_jump (insn
, nlabel
))
1647 /* Look for if (foo) bar; else break; */
1648 /* The insns look like this:
1649 insn = condjump label1;
1650 ...range1 (some insns)...
1653 ...range2 (some insns)...
1654 jump somewhere unconditionally
1657 rtx label1
= next_label (insn
);
1658 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1659 /* Don't do this optimization on the first round, so that
1660 jump-around-a-jump gets simplified before we ask here
1661 whether a jump is unconditional.
1663 Also don't do it when we are called after reload since
1664 it will confuse reorg. */
1666 && (reload_completed
? ! flag_delayed_branch
: 1)
1667 /* Make sure INSN is something we can invert. */
1668 && condjump_p (insn
)
1670 && JUMP_LABEL (insn
) == label1
1671 && LABEL_NUSES (label1
) == 1
1672 && GET_CODE (range1end
) == JUMP_INSN
1673 && simplejump_p (range1end
))
1675 rtx label2
= next_label (label1
);
1676 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
1677 if (range1end
!= range2end
1678 && JUMP_LABEL (range1end
) == label2
1679 && GET_CODE (range2end
) == JUMP_INSN
1680 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
1681 /* Invert the jump condition, so we
1682 still execute the same insns in each case. */
1683 && invert_jump (insn
, label1
))
1685 rtx range1beg
= next_active_insn (insn
);
1686 rtx range2beg
= next_active_insn (label1
);
1687 rtx range1after
, range2after
;
1688 rtx range1before
, range2before
;
1690 /* Include in each range any line number before it. */
1691 while (PREV_INSN (range1beg
)
1692 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
1693 && NOTE_LINE_NUMBER (PREV_INSN (range1beg
)) > 0)
1694 range1beg
= PREV_INSN (range1beg
);
1696 while (PREV_INSN (range2beg
)
1697 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
1698 && NOTE_LINE_NUMBER (PREV_INSN (range2beg
)) > 0)
1699 range2beg
= PREV_INSN (range2beg
);
1701 /* Don't move NOTEs for blocks or loops; shift them
1702 outside the ranges, where they'll stay put. */
1703 range1beg
= squeeze_notes (range1beg
, range1end
);
1704 range2beg
= squeeze_notes (range2beg
, range2end
);
1706 /* Get current surrounds of the 2 ranges. */
1707 range1before
= PREV_INSN (range1beg
);
1708 range2before
= PREV_INSN (range2beg
);
1709 range1after
= NEXT_INSN (range1end
);
1710 range2after
= NEXT_INSN (range2end
);
1712 /* Splice range2 where range1 was. */
1713 NEXT_INSN (range1before
) = range2beg
;
1714 PREV_INSN (range2beg
) = range1before
;
1715 NEXT_INSN (range2end
) = range1after
;
1716 PREV_INSN (range1after
) = range2end
;
1717 /* Splice range1 where range2 was. */
1718 NEXT_INSN (range2before
) = range1beg
;
1719 PREV_INSN (range1beg
) = range2before
;
1720 NEXT_INSN (range1end
) = range2after
;
1721 PREV_INSN (range2after
) = range1end
;
1728 /* Now that the jump has been tensioned,
1729 try cross jumping: check for identical code
1730 before the jump and before its target label. */
1732 /* First, cross jumping of conditional jumps: */
1734 if (cross_jump
&& condjump_p (insn
))
1736 rtx newjpos
, newlpos
;
1737 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
1739 /* A conditional jump may be crossjumped
1740 only if the place it jumps to follows
1741 an opposing jump that comes back here. */
1743 if (x
!= 0 && ! jump_back_p (x
, insn
))
1744 /* We have no opposing jump;
1745 cannot cross jump this insn. */
1749 /* TARGET is nonzero if it is ok to cross jump
1750 to code before TARGET. If so, see if matches. */
1752 find_cross_jump (insn
, x
, 2,
1753 &newjpos
, &newlpos
);
1757 do_cross_jump (insn
, newjpos
, newlpos
);
1758 /* Make the old conditional jump
1759 into an unconditional one. */
1760 SET_SRC (PATTERN (insn
))
1761 = gen_rtx (LABEL_REF
, VOIDmode
, JUMP_LABEL (insn
));
1762 INSN_CODE (insn
) = -1;
1763 emit_barrier_after (insn
);
1764 /* Add to jump_chain unless this is a new label
1765 whose UID is too large. */
1766 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
1768 jump_chain
[INSN_UID (insn
)]
1769 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1770 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
1777 /* Cross jumping of unconditional jumps:
1778 a few differences. */
1780 if (cross_jump
&& simplejump_p (insn
))
1782 rtx newjpos
, newlpos
;
1787 /* TARGET is nonzero if it is ok to cross jump
1788 to code before TARGET. If so, see if matches. */
1789 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
1790 &newjpos
, &newlpos
);
1792 /* If cannot cross jump to code before the label,
1793 see if we can cross jump to another jump to
1795 /* Try each other jump to this label. */
1796 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
1797 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1798 target
!= 0 && newjpos
== 0;
1799 target
= jump_chain
[INSN_UID (target
)])
1801 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
1802 /* Ignore TARGET if it's deleted. */
1803 && ! INSN_DELETED_P (target
))
1804 find_cross_jump (insn
, target
, 2,
1805 &newjpos
, &newlpos
);
1809 do_cross_jump (insn
, newjpos
, newlpos
);
1815 /* This code was dead in the previous jump.c! */
1816 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
1818 /* Return insns all "jump to the same place"
1819 so we can cross-jump between any two of them. */
1821 rtx newjpos
, newlpos
, target
;
1825 /* If cannot cross jump to code before the label,
1826 see if we can cross jump to another jump to
1828 /* Try each other jump to this label. */
1829 for (target
= jump_chain
[0];
1830 target
!= 0 && newjpos
== 0;
1831 target
= jump_chain
[INSN_UID (target
)])
1833 && ! INSN_DELETED_P (target
)
1834 && GET_CODE (PATTERN (target
)) == RETURN
)
1835 find_cross_jump (insn
, target
, 2,
1836 &newjpos
, &newlpos
);
1840 do_cross_jump (insn
, newjpos
, newlpos
);
1851 /* Delete extraneous line number notes.
1852 Note that two consecutive notes for different lines are not really
1853 extraneous. There should be some indication where that line belonged,
1854 even if it became empty. */
1859 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
1860 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
1862 /* Delete this note if it is identical to previous note. */
1864 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
1865 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
1875 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1876 If so, delete it, and record that this function can drop off the end. */
1882 /* One label can follow the end-note: the return label. */
1883 && ((GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
1884 /* Ordinary insns can follow it if returning a structure. */
1885 || GET_CODE (insn
) == INSN
1886 /* If machine uses explicit RETURN insns, no epilogue,
1887 then one of them follows the note. */
1888 || (GET_CODE (insn
) == JUMP_INSN
1889 && GET_CODE (PATTERN (insn
)) == RETURN
)
1890 /* Other kinds of notes can follow also. */
1891 || (GET_CODE (insn
) == NOTE
1892 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)))
1893 insn
= PREV_INSN (insn
);
1896 /* Report if control can fall through at the end of the function. */
1897 if (insn
&& GET_CODE (insn
) == NOTE
1898 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
)
1904 /* Show JUMP_CHAIN no longer valid. */
1908 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1909 jump. Assume that this unconditional jump is to the exit test code. If
1910 the code is sufficiently simple, make a copy of it before INSN,
1911 followed by a jump to the exit of the loop. Then delete the unconditional
1914 Note that it is possible we can get confused here if the jump immediately
1915 after the loop start branches outside the loop but within an outer loop.
1916 If we are near the exit of that loop, we will copy its exit test. This
1917 will not generate incorrect code, but could suppress some optimizations.
1918 However, such cases are degenerate loops anyway.
1920 Return 1 if we made the change, else 0.
1922 This is only safe immediately after a regscan pass because it uses the
1923 values of regno_first_uid and regno_last_uid. */
1926 duplicate_loop_exit_test (loop_start
)
1932 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
1934 int max_reg
= max_reg_num ();
1937 /* Scan the exit code. We do not perform this optimization if any insn:
1941 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1942 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1943 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1946 Also, don't do this if the exit code is more than 20 insns. */
1948 for (insn
= exitcode
;
1950 && ! (GET_CODE (insn
) == NOTE
1951 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
1952 insn
= NEXT_INSN (insn
))
1954 switch (GET_CODE (insn
))
1960 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
1961 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
1962 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
1967 if (++num_insns
> 20
1968 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
1969 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
1975 /* Unless INSN is zero, we can do the optimization. */
1981 /* See if any insn sets a register only used in the loop exit code and
1982 not a user variable. If so, replace it with a new register. */
1983 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
1984 if (GET_CODE (insn
) == INSN
1985 && (set
= single_set (insn
)) != 0
1986 && GET_CODE (SET_DEST (set
)) == REG
1987 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
1988 && regno_first_uid
[REGNO (SET_DEST (set
))] == INSN_UID (insn
))
1990 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
1991 if (regno_last_uid
[REGNO (SET_DEST (set
))] == INSN_UID (p
))
1996 /* We can do the replacement. Allocate reg_map if this is the
1997 first replacement we found. */
2000 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
2001 bzero (reg_map
, max_reg
* sizeof (rtx
));
2004 REG_LOOP_TEST_P (SET_DEST (set
)) = 1;
2006 reg_map
[REGNO (SET_DEST (set
))]
2007 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
2011 /* Now copy each insn. */
2012 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2013 switch (GET_CODE (insn
))
2016 copy
= emit_barrier_before (loop_start
);
2019 /* Only copy line-number notes. */
2020 if (NOTE_LINE_NUMBER (insn
) >= 0)
2022 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
2023 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
2028 copy
= emit_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2030 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2032 mark_jump_label (PATTERN (copy
), copy
, 0);
2034 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2036 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2037 if (REG_NOTE_KIND (link
) != REG_LABEL
)
2039 = copy_rtx (gen_rtx (EXPR_LIST
, REG_NOTE_KIND (link
),
2040 XEXP (link
, 0), REG_NOTES (copy
)));
2041 if (reg_map
&& REG_NOTES (copy
))
2042 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2046 copy
= emit_jump_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2048 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2049 mark_jump_label (PATTERN (copy
), copy
, 0);
2050 if (REG_NOTES (insn
))
2052 REG_NOTES (copy
) = copy_rtx (REG_NOTES (insn
));
2054 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2057 /* If this is a simple jump, add it to the jump chain. */
2059 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
2060 && simplejump_p (copy
))
2062 jump_chain
[INSN_UID (copy
)]
2063 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2064 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2072 /* Now clean up by emitting a jump to the end label and deleting the jump
2073 at the start of the loop. */
2074 if (GET_CODE (copy
) != BARRIER
)
2076 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
2078 mark_jump_label (PATTERN (copy
), copy
, 0);
2079 if (INSN_UID (copy
) < max_jump_chain
2080 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
2082 jump_chain
[INSN_UID (copy
)]
2083 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2084 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2086 emit_barrier_before (loop_start
);
2089 delete_insn (next_nonnote_insn (loop_start
));
2091 /* Mark the exit code as the virtual top of the converted loop. */
2092 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
2097 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2098 loop-end notes between START and END out before START. Assume that
2099 END is not such a note. START may be such a note. Returns the value
2100 of the new starting insn, which may be different if the original start
2104 squeeze_notes (start
, end
)
2110 for (insn
= start
; insn
!= end
; insn
= next
)
2112 next
= NEXT_INSN (insn
);
2113 if (GET_CODE (insn
) == NOTE
2114 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2115 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2116 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2117 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
2118 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
2119 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
2125 rtx prev
= PREV_INSN (insn
);
2126 PREV_INSN (insn
) = PREV_INSN (start
);
2127 NEXT_INSN (insn
) = start
;
2128 NEXT_INSN (PREV_INSN (insn
)) = insn
;
2129 PREV_INSN (NEXT_INSN (insn
)) = insn
;
2130 NEXT_INSN (prev
) = next
;
2131 PREV_INSN (next
) = prev
;
2139 /* Compare the instructions before insn E1 with those before E2
2140 to find an opportunity for cross jumping.
2141 (This means detecting identical sequences of insns followed by
2142 jumps to the same place, or followed by a label and a jump
2143 to that label, and replacing one with a jump to the other.)
2145 Assume E1 is a jump that jumps to label E2
2146 (that is not always true but it might as well be).
2147 Find the longest possible equivalent sequences
2148 and store the first insns of those sequences into *F1 and *F2.
2149 Store zero there if no equivalent preceding instructions are found.
2151 We give up if we find a label in stream 1.
2152 Actually we could transfer that label into stream 2. */
2155 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
2160 register rtx i1
= e1
, i2
= e2
;
2161 register rtx p1
, p2
;
2164 rtx last1
= 0, last2
= 0;
2165 rtx afterlast1
= 0, afterlast2
= 0;
2173 i1
= prev_nonnote_insn (i1
);
2175 i2
= PREV_INSN (i2
);
2176 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
2177 i2
= PREV_INSN (i2
);
2182 /* Don't allow the range of insns preceding E1 or E2
2183 to include the other (E2 or E1). */
2184 if (i2
== e1
|| i1
== e2
)
2187 /* If we will get to this code by jumping, those jumps will be
2188 tensioned to go directly to the new label (before I2),
2189 so this cross-jumping won't cost extra. So reduce the minimum. */
2190 if (GET_CODE (i1
) == CODE_LABEL
)
2196 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
2203 /* If cross_jump_death_matters is not 0, the insn's mode
2204 indicates whether or not the insn contains any stack-like
2207 if (cross_jump_death_matters
&& GET_MODE (i1
) == QImode
)
2209 /* If register stack conversion has already been done, then
2210 death notes must also be compared before it is certain that
2211 the two instruction streams match. */
2214 HARD_REG_SET i1_regset
, i2_regset
;
2216 CLEAR_HARD_REG_SET (i1_regset
);
2217 CLEAR_HARD_REG_SET (i2_regset
);
2219 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
2220 if (REG_NOTE_KIND (note
) == REG_DEAD
2221 && STACK_REG_P (XEXP (note
, 0)))
2222 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
2224 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
2225 if (REG_NOTE_KIND (note
) == REG_DEAD
2226 && STACK_REG_P (XEXP (note
, 0)))
2227 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
2229 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
2238 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
2239 || ! rtx_renumbered_equal_p (p1
, p2
))
2241 /* The following code helps take care of G++ cleanups. */
2245 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
2246 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
2247 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
2248 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
2249 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
2250 /* If the equivalences are not to a constant, they may
2251 reference pseudos that no longer exist, so we can't
2253 && CONSTANT_P (XEXP (equiv1
, 0))
2254 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
2256 rtx s1
= single_set (i1
);
2257 rtx s2
= single_set (i2
);
2258 if (s1
!= 0 && s2
!= 0
2259 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
2261 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
2262 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
2263 if (! rtx_renumbered_equal_p (p1
, p2
))
2265 else if (apply_change_group ())
2270 /* Insns fail to match; cross jumping is limited to the following
2274 /* Don't allow the insn after a compare to be shared by
2275 cross-jumping unless the compare is also shared.
2276 Here, if either of these non-matching insns is a compare,
2277 exclude the following insn from possible cross-jumping. */
2278 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
2279 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
2282 /* If cross-jumping here will feed a jump-around-jump
2283 optimization, this jump won't cost extra, so reduce
2285 if (GET_CODE (i1
) == JUMP_INSN
2287 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
2293 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
2295 /* Ok, this insn is potentially includable in a cross-jump here. */
2296 afterlast1
= last1
, afterlast2
= last2
;
2297 last1
= i1
, last2
= i2
, --minimum
;
2301 /* We have to be careful that we do not cross-jump into the middle of
2302 USE-CALL_INSN-CLOBBER sequence. This sequence is used instead of
2303 putting the USE and CLOBBERs inside the CALL_INSN. The delay slot
2304 scheduler needs to know what registers are used and modified by the
2305 CALL_INSN and needs the adjacent USE and CLOBBERs to do so.
2307 ??? At some point we should probably change this so that these are
2308 part of the CALL_INSN. The way we are doing it now is a kludge that
2309 is now causing trouble. */
2311 if (last1
!= 0 && GET_CODE (last1
) == CALL_INSN
2312 && (prev1
= prev_nonnote_insn (last1
))
2313 && GET_CODE (prev1
) == INSN
2314 && GET_CODE (PATTERN (prev1
)) == USE
)
2316 /* Remove this CALL_INSN from the range we can cross-jump. */
2317 last1
= next_real_insn (last1
);
2318 last2
= next_real_insn (last2
);
2323 /* Skip past CLOBBERS since they may be right after a CALL_INSN. It
2324 isn't worth checking for the CALL_INSN. */
2325 while (last1
!= 0 && GET_CODE (PATTERN (last1
)) == CLOBBER
)
2326 last1
= next_real_insn (last1
), last2
= next_real_insn (last2
);
2328 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
2329 *f1
= last1
, *f2
= last2
;
2333 do_cross_jump (insn
, newjpos
, newlpos
)
2334 rtx insn
, newjpos
, newlpos
;
2336 /* Find an existing label at this point
2337 or make a new one if there is none. */
2338 register rtx label
= get_label_before (newlpos
);
2340 /* Make the same jump insn jump to the new point. */
2341 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2343 /* Remove from jump chain of returns. */
2344 delete_from_jump_chain (insn
);
2345 /* Change the insn. */
2346 PATTERN (insn
) = gen_jump (label
);
2347 INSN_CODE (insn
) = -1;
2348 JUMP_LABEL (insn
) = label
;
2349 LABEL_NUSES (label
)++;
2350 /* Add to new the jump chain. */
2351 if (INSN_UID (label
) < max_jump_chain
2352 && INSN_UID (insn
) < max_jump_chain
)
2354 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
2355 jump_chain
[INSN_UID (label
)] = insn
;
2359 redirect_jump (insn
, label
);
2361 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2362 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2363 the NEWJPOS stream. */
2365 while (newjpos
!= insn
)
2369 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
2370 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
2371 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
2372 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
2373 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
2374 remove_note (newlpos
, lnote
);
2376 delete_insn (newjpos
);
2377 newjpos
= next_real_insn (newjpos
);
2378 newlpos
= next_real_insn (newlpos
);
2382 /* Return the label before INSN, or put a new label there. */
2385 get_label_before (insn
)
2390 /* Find an existing label at this point
2391 or make a new one if there is none. */
2392 label
= prev_nonnote_insn (insn
);
2394 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2396 rtx prev
= PREV_INSN (insn
);
2398 /* Don't put a label between a CALL_INSN and USE insns that precede
2401 if (GET_CODE (insn
) == CALL_INSN
2402 || (GET_CODE (insn
) == INSN
&& GET_CODE (PATTERN (insn
)) == SEQUENCE
2403 && GET_CODE (XVECEXP (PATTERN (insn
), 0, 0)) == CALL_INSN
))
2404 while (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == USE
)
2405 prev
= PREV_INSN (prev
);
2407 label
= gen_label_rtx ();
2408 emit_label_after (label
, prev
);
2409 LABEL_NUSES (label
) = 0;
2414 /* Return the label after INSN, or put a new label there. */
2417 get_label_after (insn
)
2422 /* Find an existing label at this point
2423 or make a new one if there is none. */
2424 label
= next_nonnote_insn (insn
);
2426 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
2428 /* Don't put a label between a CALL_INSN and CLOBBER insns
2431 if (GET_CODE (insn
) == CALL_INSN
2432 || (GET_CODE (insn
) == INSN
&& GET_CODE (PATTERN (insn
)) == SEQUENCE
2433 && GET_CODE (XVECEXP (PATTERN (insn
), 0, 0)) == CALL_INSN
))
2434 while (GET_CODE (NEXT_INSN (insn
)) == INSN
2435 && GET_CODE (PATTERN (NEXT_INSN (insn
))) == CLOBBER
)
2436 insn
= NEXT_INSN (insn
);
2438 label
= gen_label_rtx ();
2439 emit_label_after (label
, insn
);
2440 LABEL_NUSES (label
) = 0;
2445 /* Return 1 if INSN is a jump that jumps to right after TARGET
2446 only on the condition that TARGET itself would drop through.
2447 Assumes that TARGET is a conditional jump. */
2450 jump_back_p (insn
, target
)
2454 enum rtx_code codei
, codet
;
2456 if (simplejump_p (insn
) || ! condjump_p (insn
)
2457 || simplejump_p (target
)
2458 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
2461 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
2462 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
2464 codei
= GET_CODE (cinsn
);
2465 codet
= GET_CODE (ctarget
);
2467 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
2469 if (! can_reverse_comparison_p (cinsn
, insn
))
2471 codei
= reverse_condition (codei
);
2474 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
2476 if (! can_reverse_comparison_p (ctarget
, target
))
2478 codet
= reverse_condition (codet
);
2481 return (codei
== codet
2482 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
2483 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
2486 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2487 return non-zero if it is safe to reverse this comparison. It is if our
2488 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2489 this is known to be an integer comparison. */
2492 can_reverse_comparison_p (comparison
, insn
)
2498 /* If this is not actually a comparison, we can't reverse it. */
2499 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
2502 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
2503 /* If this is an NE comparison, it is safe to reverse it to an EQ
2504 comparison and vice versa, even for floating point. If no operands
2505 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2506 always false and NE is always true, so the reversal is also valid. */
2507 || GET_CODE (comparison
) == NE
2508 || GET_CODE (comparison
) == EQ
)
2511 arg0
= XEXP (comparison
, 0);
2513 /* Make sure ARG0 is one of the actual objects being compared. If we
2514 can't do this, we can't be sure the comparison can be reversed.
2516 Handle cc0 and a MODE_CC register. */
2517 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
2523 rtx prev
= prev_nonnote_insn (insn
);
2524 rtx set
= single_set (prev
);
2526 if (set
== 0 || SET_DEST (set
) != arg0
)
2529 arg0
= SET_SRC (set
);
2531 if (GET_CODE (arg0
) == COMPARE
)
2532 arg0
= XEXP (arg0
, 0);
2535 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2536 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2537 return (GET_CODE (arg0
) == CONST_INT
2538 || (GET_MODE (arg0
) != VOIDmode
2539 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
2540 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
2543 /* Given an rtx-code for a comparison, return the code
2544 for the negated comparison.
2545 WATCH OUT! reverse_condition is not safe to use on a jump
2546 that might be acting on the results of an IEEE floating point comparison,
2547 because of the special treatment of non-signaling nans in comparisons.
2548 Use can_reverse_comparison_p to be sure. */
2551 reverse_condition (code
)
2592 /* Similar, but return the code when two operands of a comparison are swapped.
2593 This IS safe for IEEE floating-point. */
2596 swap_condition (code
)
2635 /* Given a comparison CODE, return the corresponding unsigned comparison.
2636 If CODE is an equality comparison or already an unsigned comparison,
2637 CODE is returned. */
2640 unsigned_condition (code
)
2670 /* Similarly, return the signed version of a comparison. */
2673 signed_condition (code
)
2703 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2704 truth of CODE1 implies the truth of CODE2. */
2707 comparison_dominates_p (code1
, code2
)
2708 enum rtx_code code1
, code2
;
2716 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
2744 /* Return 1 if INSN is an unconditional jump and nothing else. */
2750 return (GET_CODE (insn
) == JUMP_INSN
2751 && GET_CODE (PATTERN (insn
)) == SET
2752 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
2753 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
2756 /* Return nonzero if INSN is a (possibly) conditional jump
2757 and nothing more. */
2763 register rtx x
= PATTERN (insn
);
2764 if (GET_CODE (x
) != SET
)
2766 if (GET_CODE (SET_DEST (x
)) != PC
)
2768 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
2770 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
2772 if (XEXP (SET_SRC (x
), 2) == pc_rtx
2773 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
2774 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
2776 if (XEXP (SET_SRC (x
), 1) == pc_rtx
2777 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
2778 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
2783 /* Return 1 if X is an RTX that does nothing but set the condition codes
2784 and CLOBBER or USE registers.
2785 Return -1 if X does explicitly set the condition codes,
2786 but also does other things. */
2793 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
2795 if (GET_CODE (x
) == PARALLEL
)
2799 int other_things
= 0;
2800 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2802 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
2803 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
2805 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
2808 return ! sets_cc0
? 0 : other_things
? -1 : 1;
2816 /* Follow any unconditional jump at LABEL;
2817 return the ultimate label reached by any such chain of jumps.
2818 If LABEL is not followed by a jump, return LABEL.
2819 If the chain loops or we can't find end, return LABEL,
2820 since that tells caller to avoid changing the insn.
2822 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2823 a USE or CLOBBER. */
2826 follow_jumps (label
)
2831 register rtx value
= label
;
2836 && (insn
= next_active_insn (value
)) != 0
2837 && GET_CODE (insn
) == JUMP_INSN
2838 && (JUMP_LABEL (insn
) != 0 || GET_CODE (PATTERN (insn
)) == RETURN
)
2839 && (next
= NEXT_INSN (insn
))
2840 && GET_CODE (next
) == BARRIER
);
2843 /* Don't chain through the insn that jumps into a loop
2844 from outside the loop,
2845 since that would create multiple loop entry jumps
2846 and prevent loop optimization. */
2848 if (!reload_completed
)
2849 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
2850 if (GET_CODE (tem
) == NOTE
2851 && NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
)
2854 /* If we have found a cycle, make the insn jump to itself. */
2855 if (JUMP_LABEL (insn
) == label
)
2857 value
= JUMP_LABEL (insn
);
2864 /* Assuming that field IDX of X is a vector of label_refs,
2865 replace each of them by the ultimate label reached by it.
2866 Return nonzero if a change is made.
2867 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2870 tension_vector_labels (x
, idx
)
2876 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
2878 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
2879 register rtx nlabel
= follow_jumps (olabel
);
2880 if (nlabel
&& nlabel
!= olabel
)
2882 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
2883 ++LABEL_NUSES (nlabel
);
2884 if (--LABEL_NUSES (olabel
) == 0)
2885 delete_insn (olabel
);
2892 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2893 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2894 in INSN, then store one of them in JUMP_LABEL (INSN).
2895 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2896 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2897 Also, when there are consecutive labels, canonicalize on the last of them.
2899 Note that two labels separated by a loop-beginning note
2900 must be kept distinct if we have not yet done loop-optimization,
2901 because the gap between them is where loop-optimize
2902 will want to move invariant code to. CROSS_JUMP tells us
2903 that loop-optimization is done with.
2905 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2906 two labels distinct if they are separated by only USE or CLOBBER insns. */
2909 mark_jump_label (x
, insn
, cross_jump
)
2914 register RTX_CODE code
= GET_CODE (x
);
2932 /* If this is a constant-pool reference, see if it is a label. */
2933 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
2934 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
2935 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
2940 register rtx label
= XEXP (x
, 0);
2942 if (GET_CODE (label
) != CODE_LABEL
)
2944 /* Ignore references to labels of containing functions. */
2945 if (LABEL_REF_NONLOCAL_P (x
))
2947 /* If there are other labels following this one,
2948 replace it with the last of the consecutive labels. */
2949 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
2951 if (GET_CODE (next
) == CODE_LABEL
)
2953 else if (cross_jump
&& GET_CODE (next
) == INSN
2954 && (GET_CODE (PATTERN (next
)) == USE
2955 || GET_CODE (PATTERN (next
)) == CLOBBER
))
2957 else if (GET_CODE (next
) != NOTE
)
2959 else if (! cross_jump
2960 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
2961 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
))
2964 XEXP (x
, 0) = label
;
2965 ++LABEL_NUSES (label
);
2968 if (GET_CODE (insn
) == JUMP_INSN
)
2969 JUMP_LABEL (insn
) = label
;
2970 else if (! find_reg_note (insn
, REG_LABEL
, label
))
2972 rtx next
= next_real_insn (label
);
2973 /* Don't record labels that refer to dispatch tables.
2974 This is not necessary, since the tablejump
2975 references the same label.
2976 And if we did record them, flow.c would make worse code. */
2978 || ! (GET_CODE (next
) == JUMP_INSN
2979 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
2980 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
)))
2981 REG_NOTES (insn
) = gen_rtx (EXPR_LIST
, REG_LABEL
, label
,
2988 /* Do walk the labels in a vector, but not the first operand of an
2989 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2993 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
2995 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
2996 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
, cross_jump
);
3001 fmt
= GET_RTX_FORMAT (code
);
3002 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3005 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
3006 else if (fmt
[i
] == 'E')
3009 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3010 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
3015 /* If all INSN does is set the pc, delete it,
3016 and delete the insn that set the condition codes for it
3017 if that's what the previous thing was. */
3023 register rtx x
= PATTERN (insn
);
3025 if (GET_CODE (x
) == SET
3026 && GET_CODE (SET_DEST (x
)) == PC
)
3029 rtx prev
= prev_nonnote_insn (insn
);
3030 /* We assume that at this stage
3031 CC's are always set explicitly
3032 and always immediately before the jump that
3033 will use them. So if the previous insn
3034 exists to set the CC's, delete it
3035 (unless it performs auto-increments, etc.). */
3036 if (prev
&& GET_CODE (prev
) == INSN
3037 && sets_cc0_p (PATTERN (prev
)))
3039 if (sets_cc0_p (PATTERN (prev
)) > 0
3040 && !FIND_REG_INC_NOTE (prev
, NULL_RTX
))
3043 /* Otherwise, show that cc0 won't be used. */
3044 REG_NOTES (prev
) = gen_rtx (EXPR_LIST
, REG_UNUSED
,
3045 cc0_rtx
, REG_NOTES (prev
));
3048 /* Now delete the jump insn itself. */
3049 delete_computation (insn
);
3053 /* Delete INSN and recursively delete insns that compute values used only
3054 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3055 If we are running before flow.c, we need do nothing since flow.c will
3056 delete dead code. We also can't know if the registers being used are
3057 dead or not at this point.
3059 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3060 nothing other than set a register that dies in this insn, we can delete
3061 that insn as well. */
3064 delete_computation (insn
)
3070 for (note
= REG_NOTES (insn
); note
; note
= next
)
3074 next
= XEXP (note
, 1);
3076 if (REG_NOTE_KIND (note
) != REG_DEAD
3077 /* Verify that the REG_NOTE is legitimate. */
3078 || GET_CODE (XEXP (note
, 0)) != REG
)
3081 for (our_prev
= prev_nonnote_insn (insn
);
3082 our_prev
&& GET_CODE (our_prev
) == INSN
;
3083 our_prev
= prev_nonnote_insn (our_prev
))
3085 /* If we reach a SEQUENCE, it is too complex to try to
3086 do anything with it, so give up. */
3087 if (GET_CODE (PATTERN (our_prev
)) == SEQUENCE
)
3090 if (GET_CODE (PATTERN (our_prev
)) == USE
3091 && GET_CODE (XEXP (PATTERN (our_prev
), 0)) == INSN
)
3092 /* reorg creates USEs that look like this. We leave them
3093 alone because reorg needs them for its own purposes. */
3096 if (reg_set_p (XEXP (note
, 0), PATTERN (our_prev
)))
3098 if (FIND_REG_INC_NOTE (our_prev
, NULL_RTX
))
3101 if (GET_CODE (PATTERN (our_prev
)) == PARALLEL
)
3103 /* If we find a SET of something else, we can't
3108 for (i
= 0; i
< XVECLEN (PATTERN (our_prev
), 0); i
++)
3110 rtx part
= XVECEXP (PATTERN (our_prev
), 0, i
);
3112 if (GET_CODE (part
) == SET
3113 && SET_DEST (part
) != XEXP (note
, 0))
3117 if (i
== XVECLEN (PATTERN (our_prev
), 0))
3118 delete_computation (our_prev
);
3120 else if (GET_CODE (PATTERN (our_prev
)) == SET
3121 && SET_DEST (PATTERN (our_prev
)) == XEXP (note
, 0))
3122 delete_computation (our_prev
);
3127 /* If OUR_PREV references the register that dies here, it is an
3128 additional use. Hence any prior SET isn't dead. However, this
3129 insn becomes the new place for the REG_DEAD note. */
3130 if (reg_overlap_mentioned_p (XEXP (note
, 0),
3131 PATTERN (our_prev
)))
3133 XEXP (note
, 1) = REG_NOTES (our_prev
);
3134 REG_NOTES (our_prev
) = note
;
3139 #endif /* Don't HAVE_cc0 */
3143 /* Delete insn INSN from the chain of insns and update label ref counts.
3144 May delete some following insns as a consequence; may even delete
3145 a label elsewhere and insns that follow it.
3147 Returns the first insn after INSN that was not deleted. */
3153 register rtx next
= NEXT_INSN (insn
);
3154 register rtx prev
= PREV_INSN (insn
);
3155 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
3156 register int dont_really_delete
= 0;
3158 while (next
&& INSN_DELETED_P (next
))
3159 next
= NEXT_INSN (next
);
3161 /* This insn is already deleted => return first following nondeleted. */
3162 if (INSN_DELETED_P (insn
))
3165 /* Don't delete user-declared labels. Convert them to special NOTEs
3167 if (was_code_label
&& LABEL_NAME (insn
) != 0
3168 && optimize
&& ! dont_really_delete
)
3170 PUT_CODE (insn
, NOTE
);
3171 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
3172 NOTE_SOURCE_FILE (insn
) = 0;
3173 dont_really_delete
= 1;
3176 /* Mark this insn as deleted. */
3177 INSN_DELETED_P (insn
) = 1;
3179 /* If this is an unconditional jump, delete it from the jump chain. */
3180 if (simplejump_p (insn
))
3181 delete_from_jump_chain (insn
);
3183 /* If instruction is followed by a barrier,
3184 delete the barrier too. */
3186 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
3188 INSN_DELETED_P (next
) = 1;
3189 next
= NEXT_INSN (next
);
3192 /* Patch out INSN (and the barrier if any) */
3194 if (optimize
&& ! dont_really_delete
)
3198 NEXT_INSN (prev
) = next
;
3199 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
3200 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
3201 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
3206 PREV_INSN (next
) = prev
;
3207 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
3208 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
3211 if (prev
&& NEXT_INSN (prev
) == 0)
3212 set_last_insn (prev
);
3215 /* If deleting a jump, decrement the count of the label,
3216 and delete the label if it is now unused. */
3218 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
3219 if (--LABEL_NUSES (JUMP_LABEL (insn
)) == 0)
3221 /* This can delete NEXT or PREV,
3222 either directly if NEXT is JUMP_LABEL (INSN),
3223 or indirectly through more levels of jumps. */
3224 delete_insn (JUMP_LABEL (insn
));
3225 /* I feel a little doubtful about this loop,
3226 but I see no clean and sure alternative way
3227 to find the first insn after INSN that is not now deleted.
3228 I hope this works. */
3229 while (next
&& INSN_DELETED_P (next
))
3230 next
= NEXT_INSN (next
);
3234 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
3235 prev
= PREV_INSN (prev
);
3237 /* If INSN was a label and a dispatch table follows it,
3238 delete the dispatch table. The tablejump must have gone already.
3239 It isn't useful to fall through into a table. */
3242 && NEXT_INSN (insn
) != 0
3243 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
3244 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
3245 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
3246 next
= delete_insn (NEXT_INSN (insn
));
3248 /* If INSN was a label, delete insns following it if now unreachable. */
3250 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
3252 register RTX_CODE code
;
3254 && ((code
= GET_CODE (next
)) == INSN
3255 || code
== JUMP_INSN
|| code
== CALL_INSN
3257 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
3260 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
3261 next
= NEXT_INSN (next
);
3262 /* Keep going past other deleted labels to delete what follows. */
3263 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
3264 next
= NEXT_INSN (next
);
3266 /* Note: if this deletes a jump, it can cause more
3267 deletion of unreachable code, after a different label.
3268 As long as the value from this recursive call is correct,
3269 this invocation functions correctly. */
3270 next
= delete_insn (next
);
3277 /* Advance from INSN till reaching something not deleted
3278 then return that. May return INSN itself. */
3281 next_nondeleted_insn (insn
)
3284 while (INSN_DELETED_P (insn
))
3285 insn
= NEXT_INSN (insn
);
3289 /* Delete a range of insns from FROM to TO, inclusive.
3290 This is for the sake of peephole optimization, so assume
3291 that whatever these insns do will still be done by a new
3292 peephole insn that will replace them. */
3295 delete_for_peephole (from
, to
)
3296 register rtx from
, to
;
3298 register rtx insn
= from
;
3302 register rtx next
= NEXT_INSN (insn
);
3303 register rtx prev
= PREV_INSN (insn
);
3305 if (GET_CODE (insn
) != NOTE
)
3307 INSN_DELETED_P (insn
) = 1;
3309 /* Patch this insn out of the chain. */
3310 /* We don't do this all at once, because we
3311 must preserve all NOTEs. */
3313 NEXT_INSN (prev
) = next
;
3316 PREV_INSN (next
) = prev
;
3324 /* Note that if TO is an unconditional jump
3325 we *do not* delete the BARRIER that follows,
3326 since the peephole that replaces this sequence
3327 is also an unconditional jump in that case. */
3330 /* Invert the condition of the jump JUMP, and make it jump
3331 to label NLABEL instead of where it jumps now. */
3334 invert_jump (jump
, nlabel
)
3337 register rtx olabel
= JUMP_LABEL (jump
);
3339 /* We have to either invert the condition and change the label or
3340 do neither. Either operation could fail. We first try to invert
3341 the jump. If that succeeds, we try changing the label. If that fails,
3342 we invert the jump back to what it was. */
3344 if (! invert_exp (PATTERN (jump
), jump
))
3347 if (redirect_jump (jump
, nlabel
))
3350 if (! invert_exp (PATTERN (jump
), jump
))
3351 /* This should just be putting it back the way it was. */
3357 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3359 Return 1 if we can do so, 0 if we cannot find a way to do so that
3360 matches a pattern. */
3363 invert_exp (x
, insn
)
3367 register RTX_CODE code
;
3371 code
= GET_CODE (x
);
3373 if (code
== IF_THEN_ELSE
)
3375 register rtx comp
= XEXP (x
, 0);
3378 /* We can do this in two ways: The preferable way, which can only
3379 be done if this is not an integer comparison, is to reverse
3380 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3381 of the IF_THEN_ELSE. If we can't do either, fail. */
3383 if (can_reverse_comparison_p (comp
, insn
)
3384 && validate_change (insn
, &XEXP (x
, 0),
3385 gen_rtx (reverse_condition (GET_CODE (comp
)),
3386 GET_MODE (comp
), XEXP (comp
, 0),
3387 XEXP (comp
, 1)), 0))
3391 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
3392 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
3393 return apply_change_group ();
3396 fmt
= GET_RTX_FORMAT (code
);
3397 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3400 if (! invert_exp (XEXP (x
, i
), insn
))
3405 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3406 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
3414 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3415 If the old jump target label is unused as a result,
3416 it and the code following it may be deleted.
3418 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3421 The return value will be 1 if the change was made, 0 if it wasn't (this
3422 can only occur for NLABEL == 0). */
3425 redirect_jump (jump
, nlabel
)
3428 register rtx olabel
= JUMP_LABEL (jump
);
3430 if (nlabel
== olabel
)
3433 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
3436 /* If this is an unconditional branch, delete it from the jump_chain of
3437 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3438 have UID's in range and JUMP_CHAIN is valid). */
3439 if (jump_chain
&& (simplejump_p (jump
)
3440 || GET_CODE (PATTERN (jump
)) == RETURN
))
3442 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
3444 delete_from_jump_chain (jump
);
3445 if (label_index
< max_jump_chain
3446 && INSN_UID (jump
) < max_jump_chain
)
3448 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
3449 jump_chain
[label_index
] = jump
;
3453 JUMP_LABEL (jump
) = nlabel
;
3455 ++LABEL_NUSES (nlabel
);
3457 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
3458 delete_insn (olabel
);
3463 /* Delete the instruction JUMP from any jump chain it might be on. */
3466 delete_from_jump_chain (jump
)
3470 rtx olabel
= JUMP_LABEL (jump
);
3472 /* Handle unconditional jumps. */
3473 if (jump_chain
&& olabel
!= 0
3474 && INSN_UID (olabel
) < max_jump_chain
3475 && simplejump_p (jump
))
3476 index
= INSN_UID (olabel
);
3477 /* Handle return insns. */
3478 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
3482 if (jump_chain
[index
] == jump
)
3483 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
3488 for (insn
= jump_chain
[index
];
3490 insn
= jump_chain
[INSN_UID (insn
)])
3491 if (jump_chain
[INSN_UID (insn
)] == jump
)
3493 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
3499 /* If NLABEL is nonzero, throughout the rtx at LOC,
3500 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3501 zero, alter (RETURN) to (LABEL_REF NLABEL).
3503 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3504 validity with validate_change. Convert (set (pc) (label_ref olabel))
3507 Return 0 if we found a change we would like to make but it is invalid.
3508 Otherwise, return 1. */
3511 redirect_exp (loc
, olabel
, nlabel
, insn
)
3516 register rtx x
= *loc
;
3517 register RTX_CODE code
= GET_CODE (x
);
3521 if (code
== LABEL_REF
)
3523 if (XEXP (x
, 0) == olabel
)
3526 XEXP (x
, 0) = nlabel
;
3528 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3532 else if (code
== RETURN
&& olabel
== 0)
3534 x
= gen_rtx (LABEL_REF
, VOIDmode
, nlabel
);
3535 if (loc
== &PATTERN (insn
))
3536 x
= gen_rtx (SET
, VOIDmode
, pc_rtx
, x
);
3537 return validate_change (insn
, loc
, x
, 0);
3540 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
3541 && GET_CODE (SET_SRC (x
)) == LABEL_REF
3542 && XEXP (SET_SRC (x
), 0) == olabel
)
3543 return validate_change (insn
, loc
, gen_rtx (RETURN
, VOIDmode
), 0);
3545 fmt
= GET_RTX_FORMAT (code
);
3546 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3549 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
3554 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3555 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
3563 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3565 If the old jump target label (before the dispatch table) becomes unused,
3566 it and the dispatch table may be deleted. In that case, find the insn
3567 before the jump references that label and delete it and logical successors
3571 redirect_tablejump (jump
, nlabel
)
3574 register rtx olabel
= JUMP_LABEL (jump
);
3576 /* Add this jump to the jump_chain of NLABEL. */
3577 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
3578 && INSN_UID (jump
) < max_jump_chain
)
3580 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
3581 jump_chain
[INSN_UID (nlabel
)] = jump
;
3584 PATTERN (jump
) = gen_jump (nlabel
);
3585 JUMP_LABEL (jump
) = nlabel
;
3586 ++LABEL_NUSES (nlabel
);
3587 INSN_CODE (jump
) = -1;
3589 if (--LABEL_NUSES (olabel
) == 0)
3591 delete_labelref_insn (jump
, olabel
, 0);
3592 delete_insn (olabel
);
3596 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3597 If we found one, delete it and then delete this insn if DELETE_THIS is
3598 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3601 delete_labelref_insn (insn
, label
, delete_this
)
3608 if (GET_CODE (insn
) != NOTE
3609 && reg_mentioned_p (label
, PATTERN (insn
)))
3620 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
3621 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
3635 /* Like rtx_equal_p except that it considers two REGs as equal
3636 if they renumber to the same value. */
3639 rtx_renumbered_equal_p (x
, y
)
3643 register RTX_CODE code
= GET_CODE (x
);
3648 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
3649 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
3650 && GET_CODE (SUBREG_REG (y
)) == REG
)))
3654 if (GET_MODE (x
) != GET_MODE (y
))
3657 /* If we haven't done any renumbering, don't
3658 make any assumptions. */
3659 if (reg_renumber
== 0)
3660 return rtx_equal_p (x
, y
);
3664 i
= REGNO (SUBREG_REG (x
));
3665 if (reg_renumber
[i
] >= 0)
3666 i
= reg_renumber
[i
];
3667 i
+= SUBREG_WORD (x
);
3672 if (reg_renumber
[i
] >= 0)
3673 i
= reg_renumber
[i
];
3675 if (GET_CODE (y
) == SUBREG
)
3677 j
= REGNO (SUBREG_REG (y
));
3678 if (reg_renumber
[j
] >= 0)
3679 j
= reg_renumber
[j
];
3680 j
+= SUBREG_WORD (y
);
3685 if (reg_renumber
[j
] >= 0)
3686 j
= reg_renumber
[j
];
3690 /* Now we have disposed of all the cases
3691 in which different rtx codes can match. */
3692 if (code
!= GET_CODE (y
))
3703 return XINT (x
, 0) == XINT (y
, 0);
3706 /* We can't assume nonlocal labels have their following insns yet. */
3707 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
3708 return XEXP (x
, 0) == XEXP (y
, 0);
3709 /* Two label-refs are equivalent if they point at labels
3710 in the same position in the instruction stream. */
3711 return (next_real_insn (XEXP (x
, 0))
3712 == next_real_insn (XEXP (y
, 0)));
3715 return XSTR (x
, 0) == XSTR (y
, 0);
3718 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3720 if (GET_MODE (x
) != GET_MODE (y
))
3723 /* Compare the elements. If any pair of corresponding elements
3724 fail to match, return 0 for the whole things. */
3726 fmt
= GET_RTX_FORMAT (code
);
3727 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3733 if (XWINT (x
, i
) != XWINT (y
, i
))
3738 if (XINT (x
, i
) != XINT (y
, i
))
3743 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
3748 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
3753 if (XEXP (x
, i
) != XEXP (y
, i
))
3760 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
3762 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
3763 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
3774 /* If X is a hard register or equivalent to one or a subregister of one,
3775 return the hard register number. If X is a pseudo register that was not
3776 assigned a hard register, return the pseudo register number. Otherwise,
3777 return -1. Any rtx is valid for X. */
3783 if (GET_CODE (x
) == REG
)
3785 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
3786 return reg_renumber
[REGNO (x
)];
3789 if (GET_CODE (x
) == SUBREG
)
3791 int base
= true_regnum (SUBREG_REG (x
));
3792 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
3793 return SUBREG_WORD (x
) + base
;
3798 /* Optimize code of the form:
3800 for (x = a[i]; x; ...)
3802 for (x = a[i]; x; ...)
3806 Loop optimize will change the above code into
3810 { ...; if (! (x = ...)) break; }
3813 { ...; if (! (x = ...)) break; }
3816 In general, if the first test fails, the program can branch
3817 directly to `foo' and skip the second try which is doomed to fail.
3818 We run this after loop optimization and before flow analysis. */
3820 /* When comparing the insn patterns, we track the fact that different
3821 pseudo-register numbers may have been used in each computation.
3822 The following array stores an equivalence -- same_regs[I] == J means
3823 that pseudo register I was used in the first set of tests in a context
3824 where J was used in the second set. We also count the number of such
3825 pending equivalences. If nonzero, the expressions really aren't the
3828 static short *same_regs
;
3830 static int num_same_regs
;
3832 /* Track any registers modified between the target of the first jump and
3833 the second jump. They never compare equal. */
3835 static char *modified_regs
;
3837 /* Record if memory was modified. */
3839 static int modified_mem
;
3841 /* Called via note_stores on each insn between the target of the first
3842 branch and the second branch. It marks any changed registers. */
3845 mark_modified_reg (dest
, x
)
3851 if (GET_CODE (dest
) == SUBREG
)
3852 dest
= SUBREG_REG (dest
);
3854 if (GET_CODE (dest
) == MEM
)
3857 if (GET_CODE (dest
) != REG
)
3860 regno
= REGNO (dest
);
3861 if (regno
>= FIRST_PSEUDO_REGISTER
)
3862 modified_regs
[regno
] = 1;
3864 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
3865 modified_regs
[regno
+ i
] = 1;
3868 /* F is the first insn in the chain of insns. */
3871 thread_jumps (f
, max_reg
, verbose
)
3876 /* Basic algorithm is to find a conditional branch,
3877 the label it may branch to, and the branch after
3878 that label. If the two branches test the same condition,
3879 walk back from both branch paths until the insn patterns
3880 differ, or code labels are hit. If we make it back to
3881 the target of the first branch, then we know that the first branch
3882 will either always succeed or always fail depending on the relative
3883 senses of the two branches. So adjust the first branch accordingly
3886 rtx label
, b1
, b2
, t1
, t2
;
3887 enum rtx_code code1
, code2
;
3888 rtx b1op0
, b1op1
, b2op0
, b2op1
;
3893 /* Allocate register tables and quick-reset table. */
3894 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
3895 same_regs
= (short *) alloca (max_reg
* sizeof (short));
3896 all_reset
= (short *) alloca (max_reg
* sizeof (short));
3897 for (i
= 0; i
< max_reg
; i
++)
3904 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
3906 /* Get to a candidate branch insn. */
3907 if (GET_CODE (b1
) != JUMP_INSN
3908 || ! condjump_p (b1
) || simplejump_p (b1
)
3909 || JUMP_LABEL (b1
) == 0)
3912 bzero (modified_regs
, max_reg
* sizeof (char));
3915 bcopy (all_reset
, same_regs
, max_reg
* sizeof (short));
3918 label
= JUMP_LABEL (b1
);
3920 /* Look for a branch after the target. Record any registers and
3921 memory modified between the target and the branch. Stop when we
3922 get to a label since we can't know what was changed there. */
3923 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
3925 if (GET_CODE (b2
) == CODE_LABEL
)
3928 else if (GET_CODE (b2
) == JUMP_INSN
)
3930 /* If this is an unconditional jump and is the only use of
3931 its target label, we can follow it. */
3932 if (simplejump_p (b2
)
3933 && JUMP_LABEL (b2
) != 0
3934 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
3936 b2
= JUMP_LABEL (b2
);
3943 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
3946 if (GET_CODE (b2
) == CALL_INSN
)
3949 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3950 if (call_used_regs
[i
] && ! fixed_regs
[i
]
3951 && i
!= STACK_POINTER_REGNUM
3952 && i
!= FRAME_POINTER_REGNUM
3953 && i
!= ARG_POINTER_REGNUM
)
3954 modified_regs
[i
] = 1;
3957 note_stores (PATTERN (b2
), mark_modified_reg
);
3960 /* Check the next candidate branch insn from the label
3963 || GET_CODE (b2
) != JUMP_INSN
3965 || ! condjump_p (b2
)
3966 || simplejump_p (b2
))
3969 /* Get the comparison codes and operands, reversing the
3970 codes if appropriate. If we don't have comparison codes,
3971 we can't do anything. */
3972 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
3973 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
3974 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
3975 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
3976 code1
= reverse_condition (code1
);
3978 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
3979 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
3980 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
3981 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
3982 code2
= reverse_condition (code2
);
3984 /* If they test the same things and knowing that B1 branches
3985 tells us whether or not B2 branches, check if we
3986 can thread the branch. */
3987 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
3988 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
3989 && (comparison_dominates_p (code1
, code2
)
3990 || comparison_dominates_p (code1
, reverse_condition (code2
))))
3992 t1
= prev_nonnote_insn (b1
);
3993 t2
= prev_nonnote_insn (b2
);
3995 while (t1
!= 0 && t2
!= 0)
3997 if (t1
== 0 || t2
== 0)
4002 /* We have reached the target of the first branch.
4003 If there are no pending register equivalents,
4004 we know that this branch will either always
4005 succeed (if the senses of the two branches are
4006 the same) or always fail (if not). */
4009 if (num_same_regs
!= 0)
4012 if (comparison_dominates_p (code1
, code2
))
4013 new_label
= JUMP_LABEL (b2
);
4015 new_label
= get_label_after (b2
);
4017 if (JUMP_LABEL (b1
) != new_label
4018 && redirect_jump (b1
, new_label
))
4023 /* If either of these is not a normal insn (it might be
4024 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4025 have already been skipped above.) Similarly, fail
4026 if the insns are different. */
4027 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
4028 || recog_memoized (t1
) != recog_memoized (t2
)
4029 || ! rtx_equal_for_thread_p (PATTERN (t1
),
4033 t1
= prev_nonnote_insn (t1
);
4034 t2
= prev_nonnote_insn (t2
);
4041 /* This is like RTX_EQUAL_P except that it knows about our handling of
4042 possibly equivalent registers and knows to consider volatile and
4043 modified objects as not equal.
4045 YINSN is the insn containing Y. */
4048 rtx_equal_for_thread_p (x
, y
, yinsn
)
4054 register enum rtx_code code
;
4057 code
= GET_CODE (x
);
4058 /* Rtx's of different codes cannot be equal. */
4059 if (code
!= GET_CODE (y
))
4062 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4063 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4065 if (GET_MODE (x
) != GET_MODE (y
))
4068 /* Handle special-cases first. */
4072 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
4075 /* If neither is user variable or hard register, check for possible
4077 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
4078 || REGNO (x
) < FIRST_PSEUDO_REGISTER
4079 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
4082 if (same_regs
[REGNO (x
)] == -1)
4084 same_regs
[REGNO (x
)] = REGNO (y
);
4087 /* If this is the first time we are seeing a register on the `Y'
4088 side, see if it is the last use. If not, we can't thread the
4089 jump, so mark it as not equivalent. */
4090 if (regno_last_uid
[REGNO (y
)] != INSN_UID (yinsn
))
4096 return (same_regs
[REGNO (x
)] == REGNO (y
));
4101 /* If memory modified or either volatile, not equivalent.
4102 Else, check address. */
4103 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4106 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4109 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4115 /* Cancel a pending `same_regs' if setting equivalenced registers.
4116 Then process source. */
4117 if (GET_CODE (SET_DEST (x
)) == REG
4118 && GET_CODE (SET_DEST (y
)) == REG
)
4120 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
4122 same_regs
[REGNO (SET_DEST (x
))] = -1;
4125 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
4129 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
4132 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
4135 return XEXP (x
, 0) == XEXP (y
, 0);
4138 return XSTR (x
, 0) == XSTR (y
, 0);
4144 fmt
= GET_RTX_FORMAT (code
);
4145 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4150 if (XWINT (x
, i
) != XWINT (y
, i
))
4156 if (XINT (x
, i
) != XINT (y
, i
))
4162 /* Two vectors must have the same length. */
4163 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4166 /* And the corresponding elements must match. */
4167 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4168 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
4169 XVECEXP (y
, i
, j
), yinsn
) == 0)
4174 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
4180 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4185 /* These are just backpointers, so they don't matter. */
4191 /* It is believed that rtx's at this level will never
4192 contain anything but integers and other rtx's,
4193 except for within LABEL_REFs and SYMBOL_REFs. */