1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-98, 1999 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
58 #include "hard-reg-set.h"
60 #include "insn-config.h"
61 #include "insn-flags.h"
62 #include "insn-attr.h"
69 /* ??? Eventually must record somehow the labels used by jumps
70 from nested functions. */
71 /* Pre-record the next or previous real insn for each label?
72 No, this pass is very fast anyway. */
73 /* Condense consecutive labels?
74 This would make life analysis faster, maybe. */
75 /* Optimize jump y; x: ... y: jumpif... x?
76 Don't know if it is worth bothering with. */
77 /* Optimize two cases of conditional jump to conditional jump?
78 This can never delete any instruction or make anything dead,
79 or even change what is live at any point.
80 So perhaps let combiner do it. */
82 /* Vector indexed by uid.
83 For each CODE_LABEL, index by its uid to get first unconditional jump
84 that jumps to the label.
85 For each JUMP_INSN, index by its uid to get the next unconditional jump
86 that jumps to the same label.
87 Element 0 is the start of a chain of all return insns.
88 (It is safe to use element 0 because insn uid 0 is not used. */
90 static rtx
*jump_chain
;
92 /* List of labels referred to from initializers.
93 These can never be deleted. */
96 /* Maximum index in jump_chain. */
98 static int max_jump_chain
;
100 /* Set nonzero by jump_optimize if control can fall through
101 to the end of the function. */
104 /* Indicates whether death notes are significant in cross jump analysis.
105 Normally they are not significant, because of A and B jump to C,
106 and R dies in A, it must die in B. But this might not be true after
107 stack register conversion, and we must compare death notes in that
110 static int cross_jump_death_matters
= 0;
112 static int init_label_info
PROTO((rtx
));
113 static void delete_barrier_successors
PROTO((rtx
));
114 static void mark_all_labels
PROTO((rtx
, int));
115 static rtx delete_unreferenced_labels
PROTO((rtx
));
116 static void delete_noop_moves
PROTO((rtx
));
117 static int calculate_can_reach_end
PROTO((rtx
, int, int));
118 static int duplicate_loop_exit_test
PROTO((rtx
));
119 static void find_cross_jump
PROTO((rtx
, rtx
, int, rtx
*, rtx
*));
120 static void do_cross_jump
PROTO((rtx
, rtx
, rtx
));
121 static int jump_back_p
PROTO((rtx
, rtx
));
122 static int tension_vector_labels
PROTO((rtx
, int));
123 static void mark_jump_label
PROTO((rtx
, rtx
, int));
124 static void delete_computation
PROTO((rtx
));
125 static void delete_from_jump_chain
PROTO((rtx
));
126 static int delete_labelref_insn
PROTO((rtx
, rtx
, int));
127 static void mark_modified_reg
PROTO((rtx
, rtx
));
128 static void redirect_tablejump
PROTO((rtx
, rtx
));
129 static void jump_optimize_1
PROTO ((rtx
, int, int, int, int));
131 static rtx find_insert_position
PROTO((rtx
, rtx
));
134 /* Main external entry point into the jump optimizer. See comments before
135 jump_optimize_1 for descriptions of the arguments. */
137 jump_optimize (f
, cross_jump
, noop_moves
, after_regscan
)
143 jump_optimize_1 (f
, cross_jump
, noop_moves
, after_regscan
, 0);
146 /* Alternate entry into the jump optimizer. This entry point only rebuilds
147 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
150 rebuild_jump_labels (f
)
153 jump_optimize_1 (f
, 0, 0, 0, 1);
157 /* Delete no-op jumps and optimize jumps to jumps
158 and jumps around jumps.
159 Delete unused labels and unreachable code.
161 If CROSS_JUMP is 1, detect matching code
162 before a jump and its destination and unify them.
163 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
165 If NOOP_MOVES is nonzero, delete no-op move insns.
167 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
168 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
170 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
171 and JUMP_LABEL field for jumping insns.
173 If `optimize' is zero, don't change any code,
174 just determine whether control drops off the end of the function.
175 This case occurs when we have -W and not -O.
176 It works because `delete_insn' checks the value of `optimize'
177 and refrains from actually deleting when that is 0. */
180 jump_optimize_1 (f
, cross_jump
, noop_moves
, after_regscan
, mark_labels_only
)
185 int mark_labels_only
;
187 register rtx insn
, next
;
194 cross_jump_death_matters
= (cross_jump
== 2);
195 max_uid
= init_label_info (f
) + 1;
197 /* If we are performing cross jump optimizations, then initialize
198 tables mapping UIDs to EH regions to avoid incorrect movement
199 of insns from one EH region to another. */
200 if (flag_exceptions
&& cross_jump
)
201 init_insn_eh_region (f
, max_uid
);
203 delete_barrier_successors (f
);
205 /* Leave some extra room for labels and duplicate exit test insns
207 max_jump_chain
= max_uid
* 14 / 10;
208 jump_chain
= (rtx
*) alloca (max_jump_chain
* sizeof (rtx
));
209 bzero ((char *) jump_chain
, max_jump_chain
* sizeof (rtx
));
211 mark_all_labels (f
, cross_jump
);
213 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
215 if (mark_labels_only
)
218 /* Keep track of labels used from static data;
219 they cannot ever be deleted. */
221 for (insn
= forced_labels
; insn
; insn
= XEXP (insn
, 1))
222 LABEL_NUSES (XEXP (insn
, 0))++;
224 check_exception_handler_labels ();
226 /* Keep track of labels used for marking handlers for exception
227 regions; they cannot usually be deleted. */
229 for (insn
= exception_handler_labels
; insn
; insn
= XEXP (insn
, 1))
230 LABEL_NUSES (XEXP (insn
, 0))++;
232 exception_optimize ();
234 last_insn
= delete_unreferenced_labels (f
);
238 can_reach_end
= calculate_can_reach_end (last_insn
, 1, 0);
240 /* Zero the "deleted" flag of all the "deleted" insns. */
241 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
242 INSN_DELETED_P (insn
) = 0;
244 /* Show that the jump chain is not valid. */
252 /* If we fall through to the epilogue, see if we can insert a RETURN insn
253 in front of it. If the machine allows it at this point (we might be
254 after reload for a leaf routine), it will improve optimization for it
256 insn
= get_last_insn ();
257 while (insn
&& GET_CODE (insn
) == NOTE
)
258 insn
= PREV_INSN (insn
);
260 if (insn
&& GET_CODE (insn
) != BARRIER
)
262 emit_jump_insn (gen_return ());
269 delete_noop_moves (f
);
271 /* If we haven't yet gotten to reload and we have just run regscan,
272 delete any insn that sets a register that isn't used elsewhere.
273 This helps some of the optimizations below by having less insns
274 being jumped around. */
276 if (! reload_completed
&& after_regscan
)
277 for (insn
= f
; insn
; insn
= next
)
279 rtx set
= single_set (insn
);
281 next
= NEXT_INSN (insn
);
283 if (set
&& GET_CODE (SET_DEST (set
)) == REG
284 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
285 && REGNO_FIRST_UID (REGNO (SET_DEST (set
))) == INSN_UID (insn
)
286 /* We use regno_last_note_uid so as not to delete the setting
287 of a reg that's used in notes. A subsequent optimization
288 might arrange to use that reg for real. */
289 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set
))) == INSN_UID (insn
)
290 && ! side_effects_p (SET_SRC (set
))
291 && ! find_reg_note (insn
, REG_RETVAL
, 0))
295 /* Now iterate optimizing jumps until nothing changes over one pass. */
297 old_max_reg
= max_reg_num ();
302 for (insn
= f
; insn
; insn
= next
)
305 rtx temp
, temp1
, temp2
, temp3
, temp4
, temp5
, temp6
;
307 int this_is_simplejump
, this_is_condjump
, reversep
= 0;
308 int this_is_condjump_in_parallel
;
311 /* If NOT the first iteration, if this is the last jump pass
312 (just before final), do the special peephole optimizations.
313 Avoiding the first iteration gives ordinary jump opts
314 a chance to work before peephole opts. */
316 if (reload_completed
&& !first
&& !flag_no_peephole
)
317 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
321 /* That could have deleted some insns after INSN, so check now
322 what the following insn is. */
324 next
= NEXT_INSN (insn
);
326 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
327 jump. Try to optimize by duplicating the loop exit test if so.
328 This is only safe immediately after regscan, because it uses
329 the values of regno_first_uid and regno_last_uid. */
330 if (after_regscan
&& GET_CODE (insn
) == NOTE
331 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
332 && (temp1
= next_nonnote_insn (insn
)) != 0
333 && simplejump_p (temp1
))
335 temp
= PREV_INSN (insn
);
336 if (duplicate_loop_exit_test (insn
))
339 next
= NEXT_INSN (temp
);
344 if (GET_CODE (insn
) != JUMP_INSN
)
347 this_is_simplejump
= simplejump_p (insn
);
348 this_is_condjump
= condjump_p (insn
);
349 this_is_condjump_in_parallel
= condjump_in_parallel_p (insn
);
351 /* Tension the labels in dispatch tables. */
353 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
354 changed
|= tension_vector_labels (PATTERN (insn
), 0);
355 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
356 changed
|= tension_vector_labels (PATTERN (insn
), 1);
358 /* If a dispatch table always goes to the same place,
359 get rid of it and replace the insn that uses it. */
361 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
362 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
365 rtx pat
= PATTERN (insn
);
366 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
367 int len
= XVECLEN (pat
, diff_vec_p
);
368 rtx dispatch
= prev_real_insn (insn
);
370 for (i
= 0; i
< len
; i
++)
371 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
372 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
376 && GET_CODE (dispatch
) == JUMP_INSN
377 && JUMP_LABEL (dispatch
) != 0
378 /* Don't mess with a casesi insn. */
379 && !(GET_CODE (PATTERN (dispatch
)) == SET
380 && (GET_CODE (SET_SRC (PATTERN (dispatch
)))
382 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
384 redirect_tablejump (dispatch
,
385 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
390 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
392 /* If a jump references the end of the function, try to turn
393 it into a RETURN insn, possibly a conditional one. */
394 if (JUMP_LABEL (insn
)
395 && (next_active_insn (JUMP_LABEL (insn
)) == 0
396 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn
))))
398 changed
|= redirect_jump (insn
, NULL_RTX
);
400 /* Detect jump to following insn. */
401 if (reallabelprev
== insn
&& condjump_p (insn
))
403 next
= next_real_insn (JUMP_LABEL (insn
));
409 /* If we have an unconditional jump preceded by a USE, try to put
410 the USE before the target and jump there. This simplifies many
411 of the optimizations below since we don't have to worry about
412 dealing with these USE insns. We only do this if the label
413 being branch to already has the identical USE or if code
414 never falls through to that label. */
416 if (this_is_simplejump
417 && (temp
= prev_nonnote_insn (insn
)) != 0
418 && GET_CODE (temp
) == INSN
&& GET_CODE (PATTERN (temp
)) == USE
419 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
420 && (GET_CODE (temp1
) == BARRIER
421 || (GET_CODE (temp1
) == INSN
422 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
))))
423 /* Don't do this optimization if we have a loop containing only
424 the USE instruction, and the loop start label has a usage
425 count of 1. This is because we will redo this optimization
426 everytime through the outer loop, and jump opt will never
428 && ! ((temp2
= prev_nonnote_insn (temp
)) != 0
429 && temp2
== JUMP_LABEL (insn
)
430 && LABEL_NUSES (temp2
) == 1))
432 if (GET_CODE (temp1
) == BARRIER
)
434 emit_insn_after (PATTERN (temp
), temp1
);
435 temp1
= NEXT_INSN (temp1
);
439 redirect_jump (insn
, get_label_before (temp1
));
440 reallabelprev
= prev_real_insn (temp1
);
444 /* Simplify if (...) x = a; else x = b; by converting it
445 to x = b; if (...) x = a;
446 if B is sufficiently simple, the test doesn't involve X,
447 and nothing in the test modifies B or X.
449 If we have small register classes, we also can't do this if X
452 If the "x = b;" insn has any REG_NOTES, we don't do this because
453 of the possibility that we are running after CSE and there is a
454 REG_EQUAL note that is only valid if the branch has already been
455 taken. If we move the insn with the REG_EQUAL note, we may
456 fold the comparison to always be false in a later CSE pass.
457 (We could also delete the REG_NOTES when moving the insn, but it
458 seems simpler to not move it.) An exception is that we can move
459 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
460 value is the same as "b".
462 INSN is the branch over the `else' part.
466 TEMP to the jump insn preceding "x = a;"
468 TEMP2 to the insn that sets "x = b;"
469 TEMP3 to the insn that sets "x = a;"
470 TEMP4 to the set of "x = b"; */
472 if (this_is_simplejump
473 && (temp3
= prev_active_insn (insn
)) != 0
474 && GET_CODE (temp3
) == INSN
475 && (temp4
= single_set (temp3
)) != 0
476 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
477 && (! SMALL_REGISTER_CLASSES
478 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
479 && (temp2
= next_active_insn (insn
)) != 0
480 && GET_CODE (temp2
) == INSN
481 && (temp4
= single_set (temp2
)) != 0
482 && rtx_equal_p (SET_DEST (temp4
), temp1
)
483 && ! side_effects_p (SET_SRC (temp4
))
484 && ! may_trap_p (SET_SRC (temp4
))
485 && (REG_NOTES (temp2
) == 0
486 || ((REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUAL
487 || REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUIV
)
488 && XEXP (REG_NOTES (temp2
), 1) == 0
489 && rtx_equal_p (XEXP (REG_NOTES (temp2
), 0),
491 && (temp
= prev_active_insn (temp3
)) != 0
492 && condjump_p (temp
) && ! simplejump_p (temp
)
493 /* TEMP must skip over the "x = a;" insn */
494 && prev_real_insn (JUMP_LABEL (temp
)) == insn
495 && no_labels_between_p (insn
, JUMP_LABEL (temp
))
496 /* There must be no other entries to the "x = b;" insn. */
497 && no_labels_between_p (JUMP_LABEL (temp
), temp2
)
498 /* INSN must either branch to the insn after TEMP2 or the insn
499 after TEMP2 must branch to the same place as INSN. */
500 && (reallabelprev
== temp2
501 || ((temp5
= next_active_insn (temp2
)) != 0
502 && simplejump_p (temp5
)
503 && JUMP_LABEL (temp5
) == JUMP_LABEL (insn
))))
505 /* The test expression, X, may be a complicated test with
506 multiple branches. See if we can find all the uses of
507 the label that TEMP branches to without hitting a CALL_INSN
508 or a jump to somewhere else. */
509 rtx target
= JUMP_LABEL (temp
);
510 int nuses
= LABEL_NUSES (target
);
516 /* Set P to the first jump insn that goes around "x = a;". */
517 for (p
= temp
; nuses
&& p
; p
= prev_nonnote_insn (p
))
519 if (GET_CODE (p
) == JUMP_INSN
)
521 if (condjump_p (p
) && ! simplejump_p (p
)
522 && JUMP_LABEL (p
) == target
)
531 else if (GET_CODE (p
) == CALL_INSN
)
536 /* We cannot insert anything between a set of cc and its use
537 so if P uses cc0, we must back up to the previous insn. */
538 q
= prev_nonnote_insn (p
);
539 if (q
&& GET_RTX_CLASS (GET_CODE (q
)) == 'i'
540 && sets_cc0_p (PATTERN (q
)))
547 /* If we found all the uses and there was no data conflict, we
548 can move the assignment unless we can branch into the middle
551 && no_labels_between_p (p
, insn
)
552 && ! reg_referenced_between_p (temp1
, p
, NEXT_INSN (temp3
))
553 && ! reg_set_between_p (temp1
, p
, temp3
)
554 && (GET_CODE (SET_SRC (temp4
)) == CONST_INT
555 || ! modified_between_p (SET_SRC (temp4
), p
, temp2
))
556 /* Verify that registers used by the jump are not clobbered
557 by the instruction being moved. */
558 && ! regs_set_between_p (PATTERN (temp
),
562 emit_insn_after_with_line_notes (PATTERN (temp2
), p
, temp2
);
565 /* Set NEXT to an insn that we know won't go away. */
566 next
= next_active_insn (insn
);
568 /* Delete the jump around the set. Note that we must do
569 this before we redirect the test jumps so that it won't
570 delete the code immediately following the assignment
571 we moved (which might be a jump). */
575 /* We either have two consecutive labels or a jump to
576 a jump, so adjust all the JUMP_INSNs to branch to where
578 for (p
= NEXT_INSN (p
); p
!= next
; p
= NEXT_INSN (p
))
579 if (GET_CODE (p
) == JUMP_INSN
)
580 redirect_jump (p
, target
);
587 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
588 to x = a; if (...) goto l; x = b;
589 if A is sufficiently simple, the test doesn't involve X,
590 and nothing in the test modifies A or X.
592 If we have small register classes, we also can't do this if X
595 If the "x = a;" insn has any REG_NOTES, we don't do this because
596 of the possibility that we are running after CSE and there is a
597 REG_EQUAL note that is only valid if the branch has already been
598 taken. If we move the insn with the REG_EQUAL note, we may
599 fold the comparison to always be false in a later CSE pass.
600 (We could also delete the REG_NOTES when moving the insn, but it
601 seems simpler to not move it.) An exception is that we can move
602 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
603 value is the same as "a".
609 TEMP to the jump insn preceding "x = a;"
611 TEMP2 to the insn that sets "x = b;"
612 TEMP3 to the insn that sets "x = a;"
613 TEMP4 to the set of "x = a"; */
615 if (this_is_simplejump
616 && (temp2
= next_active_insn (insn
)) != 0
617 && GET_CODE (temp2
) == INSN
618 && (temp4
= single_set (temp2
)) != 0
619 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
620 && (! SMALL_REGISTER_CLASSES
621 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
622 && (temp3
= prev_active_insn (insn
)) != 0
623 && GET_CODE (temp3
) == INSN
624 && (temp4
= single_set (temp3
)) != 0
625 && rtx_equal_p (SET_DEST (temp4
), temp1
)
626 && ! side_effects_p (SET_SRC (temp4
))
627 && ! may_trap_p (SET_SRC (temp4
))
628 && (REG_NOTES (temp3
) == 0
629 || ((REG_NOTE_KIND (REG_NOTES (temp3
)) == REG_EQUAL
630 || REG_NOTE_KIND (REG_NOTES (temp3
)) == REG_EQUIV
)
631 && XEXP (REG_NOTES (temp3
), 1) == 0
632 && rtx_equal_p (XEXP (REG_NOTES (temp3
), 0),
634 && (temp
= prev_active_insn (temp3
)) != 0
635 && condjump_p (temp
) && ! simplejump_p (temp
)
636 /* TEMP must skip over the "x = a;" insn */
637 && prev_real_insn (JUMP_LABEL (temp
)) == insn
638 && no_labels_between_p (temp
, insn
))
640 rtx prev_label
= JUMP_LABEL (temp
);
641 rtx insert_after
= prev_nonnote_insn (temp
);
644 /* We cannot insert anything between a set of cc and its use. */
645 if (insert_after
&& GET_RTX_CLASS (GET_CODE (insert_after
)) == 'i'
646 && sets_cc0_p (PATTERN (insert_after
)))
647 insert_after
= prev_nonnote_insn (insert_after
);
649 ++LABEL_NUSES (prev_label
);
652 && no_labels_between_p (insert_after
, temp
)
653 && ! reg_referenced_between_p (temp1
, insert_after
, temp3
)
654 && ! reg_referenced_between_p (temp1
, temp3
,
656 && ! reg_set_between_p (temp1
, insert_after
, temp
)
657 && ! modified_between_p (SET_SRC (temp4
), insert_after
, temp
)
658 /* Verify that registers used by the jump are not clobbered
659 by the instruction being moved. */
660 && ! regs_set_between_p (PATTERN (temp
),
663 && invert_jump (temp
, JUMP_LABEL (insn
)))
665 emit_insn_after_with_line_notes (PATTERN (temp3
),
666 insert_after
, temp3
);
669 /* Set NEXT to an insn that we know won't go away. */
673 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
674 delete_insn (prev_label
);
680 /* If we have if (...) x = exp; and branches are expensive,
681 EXP is a single insn, does not have any side effects, cannot
682 trap, and is not too costly, convert this to
683 t = exp; if (...) x = t;
685 Don't do this when we have CC0 because it is unlikely to help
686 and we'd need to worry about where to place the new insn and
687 the potential for conflicts. We also can't do this when we have
688 notes on the insn for the same reason as above.
692 TEMP to the "x = exp;" insn.
693 TEMP1 to the single set in the "x = exp;" insn.
696 if (! reload_completed
697 && this_is_condjump
&& ! this_is_simplejump
699 && (temp
= next_nonnote_insn (insn
)) != 0
700 && GET_CODE (temp
) == INSN
701 && REG_NOTES (temp
) == 0
702 && (reallabelprev
== temp
703 || ((temp2
= next_active_insn (temp
)) != 0
704 && simplejump_p (temp2
)
705 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
706 && (temp1
= single_set (temp
)) != 0
707 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
708 && (! SMALL_REGISTER_CLASSES
709 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
710 && GET_CODE (SET_SRC (temp1
)) != REG
711 && GET_CODE (SET_SRC (temp1
)) != SUBREG
712 && GET_CODE (SET_SRC (temp1
)) != CONST_INT
713 && ! side_effects_p (SET_SRC (temp1
))
714 && ! may_trap_p (SET_SRC (temp1
))
715 && rtx_cost (SET_SRC (temp1
), SET
) < 10)
717 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
719 if ((temp3
= find_insert_position (insn
, temp
))
720 && validate_change (temp
, &SET_DEST (temp1
), new, 0))
722 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
723 emit_insn_after_with_line_notes (PATTERN (temp
),
724 PREV_INSN (temp3
), temp
);
726 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
730 reg_scan_update (temp3
, NEXT_INSN (next
), old_max_reg
);
731 old_max_reg
= max_reg_num ();
736 /* Similarly, if it takes two insns to compute EXP but they
737 have the same destination. Here TEMP3 will be the second
738 insn and TEMP4 the SET from that insn. */
740 if (! reload_completed
741 && this_is_condjump
&& ! this_is_simplejump
743 && (temp
= next_nonnote_insn (insn
)) != 0
744 && GET_CODE (temp
) == INSN
745 && REG_NOTES (temp
) == 0
746 && (temp3
= next_nonnote_insn (temp
)) != 0
747 && GET_CODE (temp3
) == INSN
748 && REG_NOTES (temp3
) == 0
749 && (reallabelprev
== temp3
750 || ((temp2
= next_active_insn (temp3
)) != 0
751 && simplejump_p (temp2
)
752 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
753 && (temp1
= single_set (temp
)) != 0
754 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
755 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
756 && (! SMALL_REGISTER_CLASSES
757 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
758 && ! side_effects_p (SET_SRC (temp1
))
759 && ! may_trap_p (SET_SRC (temp1
))
760 && rtx_cost (SET_SRC (temp1
), SET
) < 10
761 && (temp4
= single_set (temp3
)) != 0
762 && rtx_equal_p (SET_DEST (temp4
), temp2
)
763 && ! side_effects_p (SET_SRC (temp4
))
764 && ! may_trap_p (SET_SRC (temp4
))
765 && rtx_cost (SET_SRC (temp4
), SET
) < 10)
767 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
769 if ((temp5
= find_insert_position (insn
, temp
))
770 && (temp6
= find_insert_position (insn
, temp3
))
771 && validate_change (temp
, &SET_DEST (temp1
), new, 0))
773 /* Use the earliest of temp5 and temp6. */
776 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
777 emit_insn_after_with_line_notes (PATTERN (temp
),
778 PREV_INSN (temp6
), temp
);
779 emit_insn_after_with_line_notes
780 (replace_rtx (PATTERN (temp3
), temp2
, new),
781 PREV_INSN (temp6
), temp3
);
784 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
788 reg_scan_update (temp6
, NEXT_INSN (next
), old_max_reg
);
789 old_max_reg
= max_reg_num ();
794 /* Finally, handle the case where two insns are used to
795 compute EXP but a temporary register is used. Here we must
796 ensure that the temporary register is not used anywhere else. */
798 if (! reload_completed
800 && this_is_condjump
&& ! this_is_simplejump
802 && (temp
= next_nonnote_insn (insn
)) != 0
803 && GET_CODE (temp
) == INSN
804 && REG_NOTES (temp
) == 0
805 && (temp3
= next_nonnote_insn (temp
)) != 0
806 && GET_CODE (temp3
) == INSN
807 && REG_NOTES (temp3
) == 0
808 && (reallabelprev
== temp3
809 || ((temp2
= next_active_insn (temp3
)) != 0
810 && simplejump_p (temp2
)
811 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
812 && (temp1
= single_set (temp
)) != 0
813 && (temp5
= SET_DEST (temp1
),
814 (GET_CODE (temp5
) == REG
815 || (GET_CODE (temp5
) == SUBREG
816 && (temp5
= SUBREG_REG (temp5
),
817 GET_CODE (temp5
) == REG
))))
818 && REGNO (temp5
) >= FIRST_PSEUDO_REGISTER
819 && REGNO_FIRST_UID (REGNO (temp5
)) == INSN_UID (temp
)
820 && REGNO_LAST_UID (REGNO (temp5
)) == INSN_UID (temp3
)
821 && ! side_effects_p (SET_SRC (temp1
))
822 && ! may_trap_p (SET_SRC (temp1
))
823 && rtx_cost (SET_SRC (temp1
), SET
) < 10
824 && (temp4
= single_set (temp3
)) != 0
825 && (temp2
= SET_DEST (temp4
), GET_CODE (temp2
) == REG
)
826 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
827 && (! SMALL_REGISTER_CLASSES
828 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
829 && rtx_equal_p (SET_DEST (temp4
), temp2
)
830 && ! side_effects_p (SET_SRC (temp4
))
831 && ! may_trap_p (SET_SRC (temp4
))
832 && rtx_cost (SET_SRC (temp4
), SET
) < 10)
834 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
836 if ((temp5
= find_insert_position (insn
, temp
))
837 && (temp6
= find_insert_position (insn
, temp3
))
838 && validate_change (temp3
, &SET_DEST (temp4
), new, 0))
840 /* Use the earliest of temp5 and temp6. */
843 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
844 emit_insn_after_with_line_notes (PATTERN (temp
),
845 PREV_INSN (temp6
), temp
);
846 emit_insn_after_with_line_notes (PATTERN (temp3
),
847 PREV_INSN (temp6
), temp3
);
850 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
854 reg_scan_update (temp6
, NEXT_INSN (next
), old_max_reg
);
855 old_max_reg
= max_reg_num ();
859 #endif /* HAVE_cc0 */
861 /* Try to use a conditional move (if the target has them), or a
862 store-flag insn. The general case is:
864 1) x = a; if (...) x = b; and
867 If the jump would be faster, the machine should not have defined
868 the movcc or scc insns!. These cases are often made by the
869 previous optimization.
871 The second case is treated as x = x; if (...) x = b;.
873 INSN here is the jump around the store. We set:
875 TEMP to the "x = b;" insn.
878 TEMP3 to A (X in the second case).
879 TEMP4 to the condition being tested.
880 TEMP5 to the earliest insn used to find the condition. */
882 if (/* We can't do this after reload has completed. */
884 && this_is_condjump
&& ! this_is_simplejump
885 /* Set TEMP to the "x = b;" insn. */
886 && (temp
= next_nonnote_insn (insn
)) != 0
887 && GET_CODE (temp
) == INSN
888 && GET_CODE (PATTERN (temp
)) == SET
889 && GET_CODE (temp1
= SET_DEST (PATTERN (temp
))) == REG
890 && (! SMALL_REGISTER_CLASSES
891 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
892 && ! side_effects_p (temp2
= SET_SRC (PATTERN (temp
)))
893 && ! may_trap_p (temp2
)
894 /* Allow either form, but prefer the former if both apply.
895 There is no point in using the old value of TEMP1 if
896 it is a register, since cse will alias them. It can
897 lose if the old value were a hard register since CSE
898 won't replace hard registers. Avoid using TEMP3 if
899 small register classes and it is a hard register. */
900 && (((temp3
= reg_set_last (temp1
, insn
)) != 0
901 && ! (SMALL_REGISTER_CLASSES
&& GET_CODE (temp3
) == REG
902 && REGNO (temp3
) < FIRST_PSEUDO_REGISTER
))
903 /* Make the latter case look like x = x; if (...) x = b; */
904 || (temp3
= temp1
, 1))
905 /* INSN must either branch to the insn after TEMP or the insn
906 after TEMP must branch to the same place as INSN. */
907 && (reallabelprev
== temp
908 || ((temp4
= next_active_insn (temp
)) != 0
909 && simplejump_p (temp4
)
910 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
911 && (temp4
= get_condition (insn
, &temp5
)) != 0
912 /* We must be comparing objects whose modes imply the size.
913 We could handle BLKmode if (1) emit_store_flag could
914 and (2) we could find the size reliably. */
915 && GET_MODE (XEXP (temp4
, 0)) != BLKmode
916 /* Even if branches are cheap, the store_flag optimization
917 can win when the operation to be performed can be
918 expressed directly. */
920 /* If the previous insn sets CC0 and something else, we can't
921 do this since we are going to delete that insn. */
923 && ! ((temp6
= prev_nonnote_insn (insn
)) != 0
924 && GET_CODE (temp6
) == INSN
925 && (sets_cc0_p (PATTERN (temp6
)) == -1
926 || (sets_cc0_p (PATTERN (temp6
)) == 1
927 && FIND_REG_INC_NOTE (temp6
, NULL_RTX
))))
931 #ifdef HAVE_conditional_move
932 /* First try a conditional move. */
934 enum rtx_code code
= GET_CODE (temp4
);
936 rtx cond0
, cond1
, aval
, bval
;
939 /* Copy the compared variables into cond0 and cond1, so that
940 any side effects performed in or after the old comparison,
941 will not affect our compare which will come later. */
942 /* ??? Is it possible to just use the comparison in the jump
943 insn? After all, we're going to delete it. We'd have
944 to modify emit_conditional_move to take a comparison rtx
945 instead or write a new function. */
946 cond0
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 0)));
947 /* We want the target to be able to simplify comparisons with
948 zero (and maybe other constants as well), so don't create
949 pseudos for them. There's no need to either. */
950 if (GET_CODE (XEXP (temp4
, 1)) == CONST_INT
951 || GET_CODE (XEXP (temp4
, 1)) == CONST_DOUBLE
)
952 cond1
= XEXP (temp4
, 1);
954 cond1
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 1)));
960 target
= emit_conditional_move (var
, code
,
961 cond0
, cond1
, VOIDmode
,
962 aval
, bval
, GET_MODE (var
),
963 (code
== LTU
|| code
== GEU
964 || code
== LEU
|| code
== GTU
));
970 /* Save the conditional move sequence but don't emit it
971 yet. On some machines, like the alpha, it is possible
972 that temp5 == insn, so next generate the sequence that
973 saves the compared values and then emit both
974 sequences ensuring seq1 occurs before seq2. */
978 /* Now that we can't fail, generate the copy insns that
979 preserve the compared values. */
981 emit_move_insn (cond0
, XEXP (temp4
, 0));
982 if (cond1
!= XEXP (temp4
, 1))
983 emit_move_insn (cond1
, XEXP (temp4
, 1));
987 emit_insns_before (seq1
, temp5
);
988 /* Insert conditional move after insn, to be sure that
989 the jump and a possible compare won't be separated */
990 last
= emit_insns_after (seq2
, insn
);
992 /* ??? We can also delete the insn that sets X to A.
993 Flow will do it too though. */
995 next
= NEXT_INSN (insn
);
1000 reg_scan_update (seq1
, NEXT_INSN (last
), old_max_reg
);
1001 old_max_reg
= max_reg_num ();
1012 /* That didn't work, try a store-flag insn.
1014 We further divide the cases into:
1016 1) x = a; if (...) x = b; and either A or B is zero,
1017 2) if (...) x = 0; and jumps are expensive,
1018 3) x = a; if (...) x = b; and A and B are constants where all
1019 the set bits in A are also set in B and jumps are expensive,
1020 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1022 5) if (...) x = b; if jumps are even more expensive. */
1024 if (GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
1025 && ((GET_CODE (temp3
) == CONST_INT
)
1026 /* Make the latter case look like
1027 x = x; if (...) x = 0; */
1030 && temp2
== const0_rtx
)
1031 || BRANCH_COST
>= 3)))
1032 /* If B is zero, OK; if A is zero, can only do (1) if we
1033 can reverse the condition. See if (3) applies possibly
1034 by reversing the condition. Prefer reversing to (4) when
1035 branches are very expensive. */
1036 && (((BRANCH_COST
>= 2
1037 || STORE_FLAG_VALUE
== -1
1038 || (STORE_FLAG_VALUE
== 1
1039 /* Check that the mask is a power of two,
1040 so that it can probably be generated
1042 && GET_CODE (temp3
) == CONST_INT
1043 && exact_log2 (INTVAL (temp3
)) >= 0))
1044 && (reversep
= 0, temp2
== const0_rtx
))
1045 || ((BRANCH_COST
>= 2
1046 || STORE_FLAG_VALUE
== -1
1047 || (STORE_FLAG_VALUE
== 1
1048 && GET_CODE (temp2
) == CONST_INT
1049 && exact_log2 (INTVAL (temp2
)) >= 0))
1050 && temp3
== const0_rtx
1051 && (reversep
= can_reverse_comparison_p (temp4
, insn
)))
1052 || (BRANCH_COST
>= 2
1053 && GET_CODE (temp2
) == CONST_INT
1054 && GET_CODE (temp3
) == CONST_INT
1055 && ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp2
)
1056 || ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp3
)
1057 && (reversep
= can_reverse_comparison_p (temp4
,
1059 || BRANCH_COST
>= 3)
1062 enum rtx_code code
= GET_CODE (temp4
);
1063 rtx uval
, cval
, var
= temp1
;
1067 /* If necessary, reverse the condition. */
1069 code
= reverse_condition (code
), uval
= temp2
, cval
= temp3
;
1071 uval
= temp3
, cval
= temp2
;
1073 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1074 is the constant 1, it is best to just compute the result
1075 directly. If UVAL is constant and STORE_FLAG_VALUE
1076 includes all of its bits, it is best to compute the flag
1077 value unnormalized and `and' it with UVAL. Otherwise,
1078 normalize to -1 and `and' with UVAL. */
1079 normalizep
= (cval
!= const0_rtx
? -1
1080 : (uval
== const1_rtx
? 1
1081 : (GET_CODE (uval
) == CONST_INT
1082 && (INTVAL (uval
) & ~STORE_FLAG_VALUE
) == 0)
1085 /* We will be putting the store-flag insn immediately in
1086 front of the comparison that was originally being done,
1087 so we know all the variables in TEMP4 will be valid.
1088 However, this might be in front of the assignment of
1089 A to VAR. If it is, it would clobber the store-flag
1090 we will be emitting.
1092 Therefore, emit into a temporary which will be copied to
1093 VAR immediately after TEMP. */
1096 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
1097 XEXP (temp4
, 0), XEXP (temp4
, 1),
1099 (code
== LTU
|| code
== LEU
1100 || code
== GEU
|| code
== GTU
),
1110 /* Put the store-flag insns in front of the first insn
1111 used to compute the condition to ensure that we
1112 use the same values of them as the current
1113 comparison. However, the remainder of the insns we
1114 generate will be placed directly in front of the
1115 jump insn, in case any of the pseudos we use
1116 are modified earlier. */
1118 emit_insns_before (seq
, temp5
);
1122 /* Both CVAL and UVAL are non-zero. */
1123 if (cval
!= const0_rtx
&& uval
!= const0_rtx
)
1127 tem1
= expand_and (uval
, target
, NULL_RTX
);
1128 if (GET_CODE (cval
) == CONST_INT
1129 && GET_CODE (uval
) == CONST_INT
1130 && (INTVAL (cval
) & INTVAL (uval
)) == INTVAL (cval
))
1134 tem2
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1135 target
, NULL_RTX
, 0);
1136 tem2
= expand_and (cval
, tem2
,
1137 (GET_CODE (tem2
) == REG
1141 /* If we usually make new pseudos, do so here. This
1142 turns out to help machines that have conditional
1144 /* ??? Conditional moves have already been handled.
1145 This may be obsolete. */
1147 if (flag_expensive_optimizations
)
1150 target
= expand_binop (GET_MODE (var
), ior_optab
,
1154 else if (normalizep
!= 1)
1156 /* We know that either CVAL or UVAL is zero. If
1157 UVAL is zero, negate TARGET and `and' with CVAL.
1158 Otherwise, `and' with UVAL. */
1159 if (uval
== const0_rtx
)
1161 target
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1162 target
, NULL_RTX
, 0);
1166 target
= expand_and (uval
, target
,
1167 (GET_CODE (target
) == REG
1168 && ! preserve_subexpressions_p ()
1169 ? target
: NULL_RTX
));
1172 emit_move_insn (var
, target
);
1176 /* If INSN uses CC0, we must not separate it from the
1177 insn that sets cc0. */
1178 if (reg_mentioned_p (cc0_rtx
, PATTERN (before
)))
1179 before
= prev_nonnote_insn (before
);
1181 emit_insns_before (seq
, before
);
1184 next
= NEXT_INSN (insn
);
1189 reg_scan_update (seq
, NEXT_INSN (next
), old_max_reg
);
1190 old_max_reg
= max_reg_num ();
1201 /* If branches are expensive, convert
1202 if (foo) bar++; to bar += (foo != 0);
1203 and similarly for "bar--;"
1205 INSN is the conditional branch around the arithmetic. We set:
1207 TEMP is the arithmetic insn.
1208 TEMP1 is the SET doing the arithmetic.
1209 TEMP2 is the operand being incremented or decremented.
1210 TEMP3 to the condition being tested.
1211 TEMP4 to the earliest insn used to find the condition. */
1213 if ((BRANCH_COST
>= 2
1221 && ! reload_completed
1222 && this_is_condjump
&& ! this_is_simplejump
1223 && (temp
= next_nonnote_insn (insn
)) != 0
1224 && (temp1
= single_set (temp
)) != 0
1225 && (temp2
= SET_DEST (temp1
),
1226 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
1227 && GET_CODE (SET_SRC (temp1
)) == PLUS
1228 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1229 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
1230 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
1231 && ! side_effects_p (temp2
)
1232 && ! may_trap_p (temp2
)
1233 /* INSN must either branch to the insn after TEMP or the insn
1234 after TEMP must branch to the same place as INSN. */
1235 && (reallabelprev
== temp
1236 || ((temp3
= next_active_insn (temp
)) != 0
1237 && simplejump_p (temp3
)
1238 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
1239 && (temp3
= get_condition (insn
, &temp4
)) != 0
1240 /* We must be comparing objects whose modes imply the size.
1241 We could handle BLKmode if (1) emit_store_flag could
1242 and (2) we could find the size reliably. */
1243 && GET_MODE (XEXP (temp3
, 0)) != BLKmode
1244 && can_reverse_comparison_p (temp3
, insn
))
1246 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
1247 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
1251 /* It must be the case that TEMP2 is not modified in the range
1252 [TEMP4, INSN). The one exception we make is if the insn
1253 before INSN sets TEMP2 to something which is also unchanged
1254 in that range. In that case, we can move the initialization
1255 into our sequence. */
1257 if ((temp5
= prev_active_insn (insn
)) != 0
1258 && no_labels_between_p (temp5
, insn
)
1259 && GET_CODE (temp5
) == INSN
1260 && (temp6
= single_set (temp5
)) != 0
1261 && rtx_equal_p (temp2
, SET_DEST (temp6
))
1262 && (CONSTANT_P (SET_SRC (temp6
))
1263 || GET_CODE (SET_SRC (temp6
)) == REG
1264 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
1266 emit_insn (PATTERN (temp5
));
1268 init
= SET_SRC (temp6
);
1271 if (CONSTANT_P (init
)
1272 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
1273 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
1274 XEXP (temp3
, 0), XEXP (temp3
, 1),
1276 (code
== LTU
|| code
== LEU
1277 || code
== GTU
|| code
== GEU
), 1);
1279 /* If we can do the store-flag, do the addition or
1283 target
= expand_binop (GET_MODE (temp2
),
1284 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1285 ? add_optab
: sub_optab
),
1286 temp2
, target
, temp2
, 0, OPTAB_WIDEN
);
1290 /* Put the result back in temp2 in case it isn't already.
1291 Then replace the jump, possible a CC0-setting insn in
1292 front of the jump, and TEMP, with the sequence we have
1295 if (target
!= temp2
)
1296 emit_move_insn (temp2
, target
);
1301 emit_insns_before (seq
, temp4
);
1305 delete_insn (init_insn
);
1307 next
= NEXT_INSN (insn
);
1309 delete_insn (prev_nonnote_insn (insn
));
1315 reg_scan_update (seq
, NEXT_INSN (next
), old_max_reg
);
1316 old_max_reg
= max_reg_num ();
1326 /* Simplify if (...) x = 1; else {...} if (x) ...
1327 We recognize this case scanning backwards as well.
1329 TEMP is the assignment to x;
1330 TEMP1 is the label at the head of the second if. */
1331 /* ?? This should call get_condition to find the values being
1332 compared, instead of looking for a COMPARE insn when HAVE_cc0
1333 is not defined. This would allow it to work on the m88k. */
1334 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1335 is not defined and the condition is tested by a separate compare
1336 insn. This is because the code below assumes that the result
1337 of the compare dies in the following branch.
1339 Not only that, but there might be other insns between the
1340 compare and branch whose results are live. Those insns need
1343 A way to fix this is to move the insns at JUMP_LABEL (insn)
1344 to before INSN. If we are running before flow, they will
1345 be deleted if they aren't needed. But this doesn't work
1348 This is really a special-case of jump threading, anyway. The
1349 right thing to do is to replace this and jump threading with
1350 much simpler code in cse.
1352 This code has been turned off in the non-cc0 case in the
1356 else if (this_is_simplejump
1357 /* Safe to skip USE and CLOBBER insns here
1358 since they will not be deleted. */
1359 && (temp
= prev_active_insn (insn
))
1360 && no_labels_between_p (temp
, insn
)
1361 && GET_CODE (temp
) == INSN
1362 && GET_CODE (PATTERN (temp
)) == SET
1363 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1364 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1365 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1366 /* If we find that the next value tested is `x'
1367 (TEMP1 is the insn where this happens), win. */
1368 && GET_CODE (temp1
) == INSN
1369 && GET_CODE (PATTERN (temp1
)) == SET
1371 /* Does temp1 `tst' the value of x? */
1372 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1373 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1374 && (temp1
= next_nonnote_insn (temp1
))
1376 /* Does temp1 compare the value of x against zero? */
1377 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1378 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1379 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1380 == SET_DEST (PATTERN (temp
)))
1381 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1382 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1384 && condjump_p (temp1
))
1386 /* Get the if_then_else from the condjump. */
1387 rtx choice
= SET_SRC (PATTERN (temp1
));
1388 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1390 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1391 rtx val
= SET_SRC (PATTERN (temp
));
1393 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1397 if (cond
== const_true_rtx
)
1398 ultimate
= XEXP (choice
, 1);
1399 else if (cond
== const0_rtx
)
1400 ultimate
= XEXP (choice
, 2);
1404 if (ultimate
== pc_rtx
)
1405 ultimate
= get_label_after (temp1
);
1406 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1407 ultimate
= XEXP (ultimate
, 0);
1409 if (ultimate
&& JUMP_LABEL(insn
) != ultimate
)
1410 changed
|= redirect_jump (insn
, ultimate
);
1416 /* @@ This needs a bit of work before it will be right.
1418 Any type of comparison can be accepted for the first and
1419 second compare. When rewriting the first jump, we must
1420 compute the what conditions can reach label3, and use the
1421 appropriate code. We can not simply reverse/swap the code
1422 of the first jump. In some cases, the second jump must be
1426 < == converts to > ==
1427 < != converts to == >
1430 If the code is written to only accept an '==' test for the second
1431 compare, then all that needs to be done is to swap the condition
1432 of the first branch.
1434 It is questionable whether we want this optimization anyways,
1435 since if the user wrote code like this because he/she knew that
1436 the jump to label1 is taken most of the time, then rewriting
1437 this gives slower code. */
1438 /* @@ This should call get_condition to find the values being
1439 compared, instead of looking for a COMPARE insn when HAVE_cc0
1440 is not defined. This would allow it to work on the m88k. */
1441 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1442 is not defined and the condition is tested by a separate compare
1443 insn. This is because the code below assumes that the result
1444 of the compare dies in the following branch. */
1446 /* Simplify test a ~= b
1460 where ~= is an inequality, e.g. >, and ~~= is the swapped
1463 We recognize this case scanning backwards.
1465 TEMP is the conditional jump to `label2';
1466 TEMP1 is the test for `a == b';
1467 TEMP2 is the conditional jump to `label1';
1468 TEMP3 is the test for `a ~= b'. */
1469 else if (this_is_simplejump
1470 && (temp
= prev_active_insn (insn
))
1471 && no_labels_between_p (temp
, insn
)
1472 && condjump_p (temp
)
1473 && (temp1
= prev_active_insn (temp
))
1474 && no_labels_between_p (temp1
, temp
)
1475 && GET_CODE (temp1
) == INSN
1476 && GET_CODE (PATTERN (temp1
)) == SET
1478 && sets_cc0_p (PATTERN (temp1
)) == 1
1480 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1481 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1482 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1484 && (temp2
= prev_active_insn (temp1
))
1485 && no_labels_between_p (temp2
, temp1
)
1486 && condjump_p (temp2
)
1487 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1488 && (temp3
= prev_active_insn (temp2
))
1489 && no_labels_between_p (temp3
, temp2
)
1490 && GET_CODE (PATTERN (temp3
)) == SET
1491 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1492 SET_DEST (PATTERN (temp1
)))
1493 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1494 SET_SRC (PATTERN (temp3
)))
1495 && ! inequality_comparisons_p (PATTERN (temp
))
1496 && inequality_comparisons_p (PATTERN (temp2
)))
1498 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1500 ++LABEL_NUSES (fallthrough_label
);
1501 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1507 if (--LABEL_NUSES (fallthrough_label
) == 0)
1508 delete_insn (fallthrough_label
);
1511 /* Simplify if (...) {... x = 1;} if (x) ...
1513 We recognize this case backwards.
1515 TEMP is the test of `x';
1516 TEMP1 is the assignment to `x' at the end of the
1517 previous statement. */
1518 /* @@ This should call get_condition to find the values being
1519 compared, instead of looking for a COMPARE insn when HAVE_cc0
1520 is not defined. This would allow it to work on the m88k. */
1521 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1522 is not defined and the condition is tested by a separate compare
1523 insn. This is because the code below assumes that the result
1524 of the compare dies in the following branch. */
1526 /* ??? This has to be turned off. The problem is that the
1527 unconditional jump might indirectly end up branching to the
1528 label between TEMP1 and TEMP. We can't detect this, in general,
1529 since it may become a jump to there after further optimizations.
1530 If that jump is done, it will be deleted, so we will retry
1531 this optimization in the next pass, thus an infinite loop.
1533 The present code prevents this by putting the jump after the
1534 label, but this is not logically correct. */
1536 else if (this_is_condjump
1537 /* Safe to skip USE and CLOBBER insns here
1538 since they will not be deleted. */
1539 && (temp
= prev_active_insn (insn
))
1540 && no_labels_between_p (temp
, insn
)
1541 && GET_CODE (temp
) == INSN
1542 && GET_CODE (PATTERN (temp
)) == SET
1544 && sets_cc0_p (PATTERN (temp
)) == 1
1545 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1547 /* Temp must be a compare insn, we can not accept a register
1548 to register move here, since it may not be simply a
1550 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1551 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1552 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1553 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1554 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1556 /* May skip USE or CLOBBER insns here
1557 for checking for opportunity, since we
1558 take care of them later. */
1559 && (temp1
= prev_active_insn (temp
))
1560 && GET_CODE (temp1
) == INSN
1561 && GET_CODE (PATTERN (temp1
)) == SET
1563 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1565 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1566 == SET_DEST (PATTERN (temp1
)))
1568 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1569 /* If this isn't true, cse will do the job. */
1570 && ! no_labels_between_p (temp1
, temp
))
1572 /* Get the if_then_else from the condjump. */
1573 rtx choice
= SET_SRC (PATTERN (insn
));
1574 if (GET_CODE (choice
) == IF_THEN_ELSE
1575 && (GET_CODE (XEXP (choice
, 0)) == EQ
1576 || GET_CODE (XEXP (choice
, 0)) == NE
))
1578 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1583 /* Get the place that condjump will jump to
1584 if it is reached from here. */
1585 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1587 ultimate
= XEXP (choice
, 1);
1589 ultimate
= XEXP (choice
, 2);
1590 /* Get it as a CODE_LABEL. */
1591 if (ultimate
== pc_rtx
)
1592 ultimate
= get_label_after (insn
);
1594 /* Get the label out of the LABEL_REF. */
1595 ultimate
= XEXP (ultimate
, 0);
1597 /* Insert the jump immediately before TEMP, specifically
1598 after the label that is between TEMP1 and TEMP. */
1599 last_insn
= PREV_INSN (temp
);
1601 /* If we would be branching to the next insn, the jump
1602 would immediately be deleted and the re-inserted in
1603 a subsequent pass over the code. So don't do anything
1605 if (next_active_insn (last_insn
)
1606 != next_active_insn (ultimate
))
1608 emit_barrier_after (last_insn
);
1609 p
= emit_jump_insn_after (gen_jump (ultimate
),
1611 JUMP_LABEL (p
) = ultimate
;
1612 ++LABEL_NUSES (ultimate
);
1613 if (INSN_UID (ultimate
) < max_jump_chain
1614 && INSN_CODE (p
) < max_jump_chain
)
1616 jump_chain
[INSN_UID (p
)]
1617 = jump_chain
[INSN_UID (ultimate
)];
1618 jump_chain
[INSN_UID (ultimate
)] = p
;
1626 /* Detect a conditional jump going to the same place
1627 as an immediately following unconditional jump. */
1628 else if (this_is_condjump
1629 && (temp
= next_active_insn (insn
)) != 0
1630 && simplejump_p (temp
)
1631 && (next_active_insn (JUMP_LABEL (insn
))
1632 == next_active_insn (JUMP_LABEL (temp
))))
1636 /* ??? Optional. Disables some optimizations, but makes
1637 gcov output more accurate with -O. */
1638 if (flag_test_coverage
&& !reload_completed
)
1639 for (tem
= insn
; tem
!= temp
; tem
= NEXT_INSN (tem
))
1640 if (GET_CODE (tem
) == NOTE
&& NOTE_LINE_NUMBER (tem
) > 0)
1651 /* Detect a conditional jump jumping over an unconditional trap. */
1653 && this_is_condjump
&& ! this_is_simplejump
1654 && reallabelprev
!= 0
1655 && GET_CODE (reallabelprev
) == INSN
1656 && GET_CODE (PATTERN (reallabelprev
)) == TRAP_IF
1657 && TRAP_CONDITION (PATTERN (reallabelprev
)) == const_true_rtx
1658 && prev_active_insn (reallabelprev
) == insn
1659 && no_labels_between_p (insn
, reallabelprev
)
1660 && (temp2
= get_condition (insn
, &temp4
))
1661 && can_reverse_comparison_p (temp2
, insn
))
1663 rtx
new = gen_cond_trap (reverse_condition (GET_CODE (temp2
)),
1664 XEXP (temp2
, 0), XEXP (temp2
, 1),
1665 TRAP_CODE (PATTERN (reallabelprev
)));
1669 emit_insn_before (new, temp4
);
1670 delete_insn (reallabelprev
);
1676 /* Detect a jump jumping to an unconditional trap. */
1677 else if (HAVE_trap
&& this_is_condjump
1678 && (temp
= next_active_insn (JUMP_LABEL (insn
)))
1679 && GET_CODE (temp
) == INSN
1680 && GET_CODE (PATTERN (temp
)) == TRAP_IF
1681 && (this_is_simplejump
1682 || (temp2
= get_condition (insn
, &temp4
))))
1684 rtx tc
= TRAP_CONDITION (PATTERN (temp
));
1686 if (tc
== const_true_rtx
1687 || (! this_is_simplejump
&& rtx_equal_p (temp2
, tc
)))
1690 /* Replace an unconditional jump to a trap with a trap. */
1691 if (this_is_simplejump
)
1693 emit_barrier_after (emit_insn_before (gen_trap (), insn
));
1698 new = gen_cond_trap (GET_CODE (temp2
), XEXP (temp2
, 0),
1700 TRAP_CODE (PATTERN (temp
)));
1703 emit_insn_before (new, temp4
);
1709 /* If the trap condition and jump condition are mutually
1710 exclusive, redirect the jump to the following insn. */
1711 else if (GET_RTX_CLASS (GET_CODE (tc
)) == '<'
1712 && ! this_is_simplejump
1713 && swap_condition (GET_CODE (temp2
)) == GET_CODE (tc
)
1714 && rtx_equal_p (XEXP (tc
, 0), XEXP (temp2
, 0))
1715 && rtx_equal_p (XEXP (tc
, 1), XEXP (temp2
, 1))
1716 && redirect_jump (insn
, get_label_after (temp
)))
1724 /* Detect a conditional jump jumping over an unconditional jump. */
1726 else if ((this_is_condjump
|| this_is_condjump_in_parallel
)
1727 && ! this_is_simplejump
1728 && reallabelprev
!= 0
1729 && GET_CODE (reallabelprev
) == JUMP_INSN
1730 && prev_active_insn (reallabelprev
) == insn
1731 && no_labels_between_p (insn
, reallabelprev
)
1732 && simplejump_p (reallabelprev
))
1734 /* When we invert the unconditional jump, we will be
1735 decrementing the usage count of its old label.
1736 Make sure that we don't delete it now because that
1737 might cause the following code to be deleted. */
1738 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
1739 rtx prev_label
= JUMP_LABEL (insn
);
1742 ++LABEL_NUSES (prev_label
);
1744 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
1746 /* It is very likely that if there are USE insns before
1747 this jump, they hold REG_DEAD notes. These REG_DEAD
1748 notes are no longer valid due to this optimization,
1749 and will cause the life-analysis that following passes
1750 (notably delayed-branch scheduling) to think that
1751 these registers are dead when they are not.
1753 To prevent this trouble, we just remove the USE insns
1754 from the insn chain. */
1756 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
1757 && GET_CODE (PATTERN (prev_uses
)) == USE
)
1759 rtx useless
= prev_uses
;
1760 prev_uses
= prev_nonnote_insn (prev_uses
);
1761 delete_insn (useless
);
1764 delete_insn (reallabelprev
);
1769 /* We can now safely delete the label if it is unreferenced
1770 since the delete_insn above has deleted the BARRIER. */
1771 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
1772 delete_insn (prev_label
);
1777 /* Detect a jump to a jump. */
1779 nlabel
= follow_jumps (JUMP_LABEL (insn
));
1780 if (nlabel
!= JUMP_LABEL (insn
)
1781 && redirect_jump (insn
, nlabel
))
1787 /* Look for if (foo) bar; else break; */
1788 /* The insns look like this:
1789 insn = condjump label1;
1790 ...range1 (some insns)...
1793 ...range2 (some insns)...
1794 jump somewhere unconditionally
1797 rtx label1
= next_label (insn
);
1798 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1799 /* Don't do this optimization on the first round, so that
1800 jump-around-a-jump gets simplified before we ask here
1801 whether a jump is unconditional.
1803 Also don't do it when we are called after reload since
1804 it will confuse reorg. */
1806 && (reload_completed
? ! flag_delayed_branch
: 1)
1807 /* Make sure INSN is something we can invert. */
1808 && condjump_p (insn
)
1810 && JUMP_LABEL (insn
) == label1
1811 && LABEL_NUSES (label1
) == 1
1812 && GET_CODE (range1end
) == JUMP_INSN
1813 && simplejump_p (range1end
))
1815 rtx label2
= next_label (label1
);
1816 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
1817 if (range1end
!= range2end
1818 && JUMP_LABEL (range1end
) == label2
1819 && GET_CODE (range2end
) == JUMP_INSN
1820 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
1821 /* Invert the jump condition, so we
1822 still execute the same insns in each case. */
1823 && invert_jump (insn
, label1
))
1825 rtx range1beg
= next_active_insn (insn
);
1826 rtx range2beg
= next_active_insn (label1
);
1827 rtx range1after
, range2after
;
1828 rtx range1before
, range2before
;
1831 /* Include in each range any notes before it, to be
1832 sure that we get the line number note if any, even
1833 if there are other notes here. */
1834 while (PREV_INSN (range1beg
)
1835 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
)
1836 range1beg
= PREV_INSN (range1beg
);
1838 while (PREV_INSN (range2beg
)
1839 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
)
1840 range2beg
= PREV_INSN (range2beg
);
1842 /* Don't move NOTEs for blocks or loops; shift them
1843 outside the ranges, where they'll stay put. */
1844 range1beg
= squeeze_notes (range1beg
, range1end
);
1845 range2beg
= squeeze_notes (range2beg
, range2end
);
1847 /* Get current surrounds of the 2 ranges. */
1848 range1before
= PREV_INSN (range1beg
);
1849 range2before
= PREV_INSN (range2beg
);
1850 range1after
= NEXT_INSN (range1end
);
1851 range2after
= NEXT_INSN (range2end
);
1853 /* Splice range2 where range1 was. */
1854 NEXT_INSN (range1before
) = range2beg
;
1855 PREV_INSN (range2beg
) = range1before
;
1856 NEXT_INSN (range2end
) = range1after
;
1857 PREV_INSN (range1after
) = range2end
;
1858 /* Splice range1 where range2 was. */
1859 NEXT_INSN (range2before
) = range1beg
;
1860 PREV_INSN (range1beg
) = range2before
;
1861 NEXT_INSN (range1end
) = range2after
;
1862 PREV_INSN (range2after
) = range1end
;
1864 /* Check for a loop end note between the end of
1865 range2, and the next code label. If there is one,
1866 then what we have really seen is
1867 if (foo) break; end_of_loop;
1868 and moved the break sequence outside the loop.
1869 We must move the LOOP_END note to where the
1870 loop really ends now, or we will confuse loop
1871 optimization. Stop if we find a LOOP_BEG note
1872 first, since we don't want to move the LOOP_END
1873 note in that case. */
1874 for (;range2after
!= label2
; range2after
= rangenext
)
1876 rangenext
= NEXT_INSN (range2after
);
1877 if (GET_CODE (range2after
) == NOTE
)
1879 if (NOTE_LINE_NUMBER (range2after
)
1880 == NOTE_INSN_LOOP_END
)
1882 NEXT_INSN (PREV_INSN (range2after
))
1884 PREV_INSN (rangenext
)
1885 = PREV_INSN (range2after
);
1886 PREV_INSN (range2after
)
1887 = PREV_INSN (range1beg
);
1888 NEXT_INSN (range2after
) = range1beg
;
1889 NEXT_INSN (PREV_INSN (range1beg
))
1891 PREV_INSN (range1beg
) = range2after
;
1893 else if (NOTE_LINE_NUMBER (range2after
)
1894 == NOTE_INSN_LOOP_BEG
)
1904 /* Now that the jump has been tensioned,
1905 try cross jumping: check for identical code
1906 before the jump and before its target label. */
1908 /* First, cross jumping of conditional jumps: */
1910 if (cross_jump
&& condjump_p (insn
))
1912 rtx newjpos
, newlpos
;
1913 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
1915 /* A conditional jump may be crossjumped
1916 only if the place it jumps to follows
1917 an opposing jump that comes back here. */
1919 if (x
!= 0 && ! jump_back_p (x
, insn
))
1920 /* We have no opposing jump;
1921 cannot cross jump this insn. */
1925 /* TARGET is nonzero if it is ok to cross jump
1926 to code before TARGET. If so, see if matches. */
1928 find_cross_jump (insn
, x
, 2,
1929 &newjpos
, &newlpos
);
1933 do_cross_jump (insn
, newjpos
, newlpos
);
1934 /* Make the old conditional jump
1935 into an unconditional one. */
1936 SET_SRC (PATTERN (insn
))
1937 = gen_rtx_LABEL_REF (VOIDmode
, JUMP_LABEL (insn
));
1938 INSN_CODE (insn
) = -1;
1939 emit_barrier_after (insn
);
1940 /* Add to jump_chain unless this is a new label
1941 whose UID is too large. */
1942 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
1944 jump_chain
[INSN_UID (insn
)]
1945 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1946 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
1953 /* Cross jumping of unconditional jumps:
1954 a few differences. */
1956 if (cross_jump
&& simplejump_p (insn
))
1958 rtx newjpos
, newlpos
;
1963 /* TARGET is nonzero if it is ok to cross jump
1964 to code before TARGET. If so, see if matches. */
1965 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
1966 &newjpos
, &newlpos
);
1968 /* If cannot cross jump to code before the label,
1969 see if we can cross jump to another jump to
1971 /* Try each other jump to this label. */
1972 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
1973 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
1974 target
!= 0 && newjpos
== 0;
1975 target
= jump_chain
[INSN_UID (target
)])
1977 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
1978 /* Ignore TARGET if it's deleted. */
1979 && ! INSN_DELETED_P (target
))
1980 find_cross_jump (insn
, target
, 2,
1981 &newjpos
, &newlpos
);
1985 do_cross_jump (insn
, newjpos
, newlpos
);
1991 /* This code was dead in the previous jump.c! */
1992 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
1994 /* Return insns all "jump to the same place"
1995 so we can cross-jump between any two of them. */
1997 rtx newjpos
, newlpos
, target
;
2001 /* If cannot cross jump to code before the label,
2002 see if we can cross jump to another jump to
2004 /* Try each other jump to this label. */
2005 for (target
= jump_chain
[0];
2006 target
!= 0 && newjpos
== 0;
2007 target
= jump_chain
[INSN_UID (target
)])
2009 && ! INSN_DELETED_P (target
)
2010 && GET_CODE (PATTERN (target
)) == RETURN
)
2011 find_cross_jump (insn
, target
, 2,
2012 &newjpos
, &newlpos
);
2016 do_cross_jump (insn
, newjpos
, newlpos
);
2027 /* Delete extraneous line number notes.
2028 Note that two consecutive notes for different lines are not really
2029 extraneous. There should be some indication where that line belonged,
2030 even if it became empty. */
2035 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2036 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
2038 /* Delete this note if it is identical to previous note. */
2040 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
2041 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
2054 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2055 in front of it. If the machine allows it at this point (we might be
2056 after reload for a leaf routine), it will improve optimization for it
2057 to be there. We do this both here and at the start of this pass since
2058 the RETURN might have been deleted by some of our optimizations. */
2059 insn
= get_last_insn ();
2060 while (insn
&& GET_CODE (insn
) == NOTE
)
2061 insn
= PREV_INSN (insn
);
2063 if (insn
&& GET_CODE (insn
) != BARRIER
)
2065 emit_jump_insn (gen_return ());
2071 can_reach_end
= calculate_can_reach_end (last_insn
, 0, 1);
2073 /* Show JUMP_CHAIN no longer valid. */
2077 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2078 notes whose labels don't occur in the insn any more. Returns the
2079 largest INSN_UID found. */
2084 int largest_uid
= 0;
2087 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2089 if (GET_CODE (insn
) == CODE_LABEL
)
2090 LABEL_NUSES (insn
) = (LABEL_PRESERVE_P (insn
) != 0);
2091 else if (GET_CODE (insn
) == JUMP_INSN
)
2092 JUMP_LABEL (insn
) = 0;
2093 else if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == CALL_INSN
)
2097 for (note
= REG_NOTES (insn
); note
; note
= next
)
2099 next
= XEXP (note
, 1);
2100 if (REG_NOTE_KIND (note
) == REG_LABEL
2101 && ! reg_mentioned_p (XEXP (note
, 0), PATTERN (insn
)))
2102 remove_note (insn
, note
);
2105 if (INSN_UID (insn
) > largest_uid
)
2106 largest_uid
= INSN_UID (insn
);
2112 /* Delete insns following barriers, up to next label.
2114 Also delete no-op jumps created by gcse. */
2116 delete_barrier_successors (f
)
2121 for (insn
= f
; insn
;)
2123 if (GET_CODE (insn
) == BARRIER
)
2125 insn
= NEXT_INSN (insn
);
2126 while (insn
!= 0 && GET_CODE (insn
) != CODE_LABEL
)
2128 if (GET_CODE (insn
) == NOTE
2129 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
2130 insn
= NEXT_INSN (insn
);
2132 insn
= delete_insn (insn
);
2134 /* INSN is now the code_label. */
2136 /* Also remove (set (pc) (pc)) insns which can be created by
2137 gcse. We eliminate such insns now to avoid having them
2138 cause problems later. */
2139 else if (GET_CODE (insn
) == JUMP_INSN
2140 && SET_SRC (PATTERN (insn
)) == pc_rtx
2141 && SET_DEST (PATTERN (insn
)) == pc_rtx
)
2142 insn
= delete_insn (insn
);
2145 insn
= NEXT_INSN (insn
);
2149 /* Mark the label each jump jumps to.
2150 Combine consecutive labels, and count uses of labels.
2152 For each label, make a chain (using `jump_chain')
2153 of all the *unconditional* jumps that jump to it;
2154 also make a chain of all returns.
2156 CROSS_JUMP indicates whether we are doing cross jumping
2157 and if we are whether we will be paying attention to
2158 death notes or not. */
2161 mark_all_labels (f
, cross_jump
)
2167 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2168 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
2170 mark_jump_label (PATTERN (insn
), insn
, cross_jump
);
2171 if (! INSN_DELETED_P (insn
) && GET_CODE (insn
) == JUMP_INSN
)
2173 if (JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
2175 jump_chain
[INSN_UID (insn
)]
2176 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
2177 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
2179 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2181 jump_chain
[INSN_UID (insn
)] = jump_chain
[0];
2182 jump_chain
[0] = insn
;
2188 /* Delete all labels already not referenced.
2189 Also find and return the last insn. */
2192 delete_unreferenced_labels (f
)
2195 rtx final
= NULL_RTX
;
2198 for (insn
= f
; insn
; )
2200 if (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NUSES (insn
) == 0)
2201 insn
= delete_insn (insn
);
2205 insn
= NEXT_INSN (insn
);
2212 /* Delete various simple forms of moves which have no necessary
2216 delete_noop_moves (f
)
2221 for (insn
= f
; insn
; )
2223 next
= NEXT_INSN (insn
);
2225 if (GET_CODE (insn
) == INSN
)
2227 register rtx body
= PATTERN (insn
);
2229 /* Combine stack_adjusts with following push_insns. */
2230 #ifdef PUSH_ROUNDING
2231 if (GET_CODE (body
) == SET
2232 && SET_DEST (body
) == stack_pointer_rtx
2233 && GET_CODE (SET_SRC (body
)) == PLUS
2234 && XEXP (SET_SRC (body
), 0) == stack_pointer_rtx
2235 && GET_CODE (XEXP (SET_SRC (body
), 1)) == CONST_INT
2236 && INTVAL (XEXP (SET_SRC (body
), 1)) > 0)
2239 rtx stack_adjust_insn
= insn
;
2240 int stack_adjust_amount
= INTVAL (XEXP (SET_SRC (body
), 1));
2241 int total_pushed
= 0;
2244 /* Find all successive push insns. */
2246 /* Don't convert more than three pushes;
2247 that starts adding too many displaced addresses
2248 and the whole thing starts becoming a losing
2253 p
= next_nonnote_insn (p
);
2254 if (p
== 0 || GET_CODE (p
) != INSN
)
2256 pbody
= PATTERN (p
);
2257 if (GET_CODE (pbody
) != SET
)
2259 dest
= SET_DEST (pbody
);
2260 /* Allow a no-op move between the adjust and the push. */
2261 if (GET_CODE (dest
) == REG
2262 && GET_CODE (SET_SRC (pbody
)) == REG
2263 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
2265 if (! (GET_CODE (dest
) == MEM
2266 && GET_CODE (XEXP (dest
, 0)) == POST_INC
2267 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
2270 if (total_pushed
+ GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)))
2271 > stack_adjust_amount
)
2273 total_pushed
+= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
2276 /* Discard the amount pushed from the stack adjust;
2277 maybe eliminate it entirely. */
2278 if (total_pushed
>= stack_adjust_amount
)
2280 delete_computation (stack_adjust_insn
);
2281 total_pushed
= stack_adjust_amount
;
2284 XEXP (SET_SRC (PATTERN (stack_adjust_insn
)), 1)
2285 = GEN_INT (stack_adjust_amount
- total_pushed
);
2287 /* Change the appropriate push insns to ordinary stores. */
2289 while (total_pushed
> 0)
2292 p
= next_nonnote_insn (p
);
2293 if (GET_CODE (p
) != INSN
)
2295 pbody
= PATTERN (p
);
2296 if (GET_CODE (pbody
) != SET
)
2298 dest
= SET_DEST (pbody
);
2299 /* Allow a no-op move between the adjust and the push. */
2300 if (GET_CODE (dest
) == REG
2301 && GET_CODE (SET_SRC (pbody
)) == REG
2302 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
2304 if (! (GET_CODE (dest
) == MEM
2305 && GET_CODE (XEXP (dest
, 0)) == POST_INC
2306 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
2308 total_pushed
-= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
2309 /* If this push doesn't fully fit in the space
2310 of the stack adjust that we deleted,
2311 make another stack adjust here for what we
2312 didn't use up. There should be peepholes
2313 to recognize the resulting sequence of insns. */
2314 if (total_pushed
< 0)
2316 emit_insn_before (gen_add2_insn (stack_pointer_rtx
,
2317 GEN_INT (- total_pushed
)),
2322 = plus_constant (stack_pointer_rtx
, total_pushed
);
2327 /* Detect and delete no-op move instructions
2328 resulting from not allocating a parameter in a register. */
2330 if (GET_CODE (body
) == SET
2331 && (SET_DEST (body
) == SET_SRC (body
)
2332 || (GET_CODE (SET_DEST (body
)) == MEM
2333 && GET_CODE (SET_SRC (body
)) == MEM
2334 && rtx_equal_p (SET_SRC (body
), SET_DEST (body
))))
2335 && ! (GET_CODE (SET_DEST (body
)) == MEM
2336 && MEM_VOLATILE_P (SET_DEST (body
)))
2337 && ! (GET_CODE (SET_SRC (body
)) == MEM
2338 && MEM_VOLATILE_P (SET_SRC (body
))))
2339 delete_computation (insn
);
2341 /* Detect and ignore no-op move instructions
2342 resulting from smart or fortuitous register allocation. */
2344 else if (GET_CODE (body
) == SET
)
2346 int sreg
= true_regnum (SET_SRC (body
));
2347 int dreg
= true_regnum (SET_DEST (body
));
2349 if (sreg
== dreg
&& sreg
>= 0)
2351 else if (sreg
>= 0 && dreg
>= 0)
2354 rtx tem
= find_equiv_reg (NULL_RTX
, insn
, 0,
2355 sreg
, NULL_PTR
, dreg
,
2356 GET_MODE (SET_SRC (body
)));
2359 && GET_MODE (tem
) == GET_MODE (SET_DEST (body
)))
2361 /* DREG may have been the target of a REG_DEAD note in
2362 the insn which makes INSN redundant. If so, reorg
2363 would still think it is dead. So search for such a
2364 note and delete it if we find it. */
2365 if (! find_regno_note (insn
, REG_UNUSED
, dreg
))
2366 for (trial
= prev_nonnote_insn (insn
);
2367 trial
&& GET_CODE (trial
) != CODE_LABEL
;
2368 trial
= prev_nonnote_insn (trial
))
2369 if (find_regno_note (trial
, REG_DEAD
, dreg
))
2371 remove_death (dreg
, trial
);
2375 /* Deleting insn could lose a death-note for SREG. */
2376 if ((trial
= find_regno_note (insn
, REG_DEAD
, sreg
)))
2378 /* Change this into a USE so that we won't emit
2379 code for it, but still can keep the note. */
2381 = gen_rtx_USE (VOIDmode
, XEXP (trial
, 0));
2382 INSN_CODE (insn
) = -1;
2383 /* Remove all reg notes but the REG_DEAD one. */
2384 REG_NOTES (insn
) = trial
;
2385 XEXP (trial
, 1) = NULL_RTX
;
2391 else if (dreg
>= 0 && CONSTANT_P (SET_SRC (body
))
2392 && find_equiv_reg (SET_SRC (body
), insn
, 0, dreg
,
2394 GET_MODE (SET_DEST (body
))))
2396 /* This handles the case where we have two consecutive
2397 assignments of the same constant to pseudos that didn't
2398 get a hard reg. Each SET from the constant will be
2399 converted into a SET of the spill register and an
2400 output reload will be made following it. This produces
2401 two loads of the same constant into the same spill
2406 /* Look back for a death note for the first reg.
2407 If there is one, it is no longer accurate. */
2408 while (in_insn
&& GET_CODE (in_insn
) != CODE_LABEL
)
2410 if ((GET_CODE (in_insn
) == INSN
2411 || GET_CODE (in_insn
) == JUMP_INSN
)
2412 && find_regno_note (in_insn
, REG_DEAD
, dreg
))
2414 remove_death (dreg
, in_insn
);
2417 in_insn
= PREV_INSN (in_insn
);
2420 /* Delete the second load of the value. */
2424 else if (GET_CODE (body
) == PARALLEL
)
2426 /* If each part is a set between two identical registers or
2427 a USE or CLOBBER, delete the insn. */
2431 for (i
= XVECLEN (body
, 0) - 1; i
>= 0; i
--)
2433 tem
= XVECEXP (body
, 0, i
);
2434 if (GET_CODE (tem
) == USE
|| GET_CODE (tem
) == CLOBBER
)
2437 if (GET_CODE (tem
) != SET
2438 || (sreg
= true_regnum (SET_SRC (tem
))) < 0
2439 || (dreg
= true_regnum (SET_DEST (tem
))) < 0
2447 /* Also delete insns to store bit fields if they are no-ops. */
2448 /* Not worth the hair to detect this in the big-endian case. */
2449 else if (! BYTES_BIG_ENDIAN
2450 && GET_CODE (body
) == SET
2451 && GET_CODE (SET_DEST (body
)) == ZERO_EXTRACT
2452 && XEXP (SET_DEST (body
), 2) == const0_rtx
2453 && XEXP (SET_DEST (body
), 0) == SET_SRC (body
)
2454 && ! (GET_CODE (SET_SRC (body
)) == MEM
2455 && MEM_VOLATILE_P (SET_SRC (body
))))
2462 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2463 If so indicate that this function can drop off the end by returning
2466 CHECK_DELETED indicates whether we must check if the note being
2467 searched for has the deleted flag set.
2469 DELETE_FINAL_NOTE indicates whether we should delete the note
2473 calculate_can_reach_end (last
, check_deleted
, delete_final_note
)
2476 int delete_final_note
;
2481 while (insn
!= NULL_RTX
)
2485 /* One label can follow the end-note: the return label. */
2486 if (GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
2488 /* Ordinary insns can follow it if returning a structure. */
2489 else if (GET_CODE (insn
) == INSN
)
2491 /* If machine uses explicit RETURN insns, no epilogue,
2492 then one of them follows the note. */
2493 else if (GET_CODE (insn
) == JUMP_INSN
2494 && GET_CODE (PATTERN (insn
)) == RETURN
)
2496 /* A barrier can follow the return insn. */
2497 else if (GET_CODE (insn
) == BARRIER
)
2499 /* Other kinds of notes can follow also. */
2500 else if (GET_CODE (insn
) == NOTE
2501 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
2507 insn
= PREV_INSN (insn
);
2510 /* See if we backed up to the appropriate type of note. */
2511 if (insn
!= NULL_RTX
2512 && GET_CODE (insn
) == NOTE
2513 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
2514 && (check_deleted
== 0
2515 || ! INSN_DELETED_P (insn
)))
2517 if (delete_final_note
)
2525 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2526 jump. Assume that this unconditional jump is to the exit test code. If
2527 the code is sufficiently simple, make a copy of it before INSN,
2528 followed by a jump to the exit of the loop. Then delete the unconditional
2531 Return 1 if we made the change, else 0.
2533 This is only safe immediately after a regscan pass because it uses the
2534 values of regno_first_uid and regno_last_uid. */
2537 duplicate_loop_exit_test (loop_start
)
2540 rtx insn
, set
, reg
, p
, link
;
2543 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
2545 int max_reg
= max_reg_num ();
2548 /* Scan the exit code. We do not perform this optimization if any insn:
2552 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2553 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2554 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2557 We also do not do this if we find an insn with ASM_OPERANDS. While
2558 this restriction should not be necessary, copying an insn with
2559 ASM_OPERANDS can confuse asm_noperands in some cases.
2561 Also, don't do this if the exit code is more than 20 insns. */
2563 for (insn
= exitcode
;
2565 && ! (GET_CODE (insn
) == NOTE
2566 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
2567 insn
= NEXT_INSN (insn
))
2569 switch (GET_CODE (insn
))
2575 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2576 a jump immediately after the loop start that branches outside
2577 the loop but within an outer loop, near the exit test.
2578 If we copied this exit test and created a phony
2579 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2580 before the exit test look like these could be safely moved
2581 out of the loop even if they actually may be never executed.
2582 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2584 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2585 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
)
2589 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2590 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
))
2591 /* If we were to duplicate this code, we would not move
2592 the BLOCK notes, and so debugging the moved code would
2593 be difficult. Thus, we only move the code with -O2 or
2600 /* The code below would grossly mishandle REG_WAS_0 notes,
2601 so get rid of them here. */
2602 while ((p
= find_reg_note (insn
, REG_WAS_0
, NULL_RTX
)) != 0)
2603 remove_note (insn
, p
);
2604 if (++num_insns
> 20
2605 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
2606 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
)
2607 || asm_noperands (PATTERN (insn
)) > 0)
2615 /* Unless INSN is zero, we can do the optimization. */
2621 /* See if any insn sets a register only used in the loop exit code and
2622 not a user variable. If so, replace it with a new register. */
2623 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2624 if (GET_CODE (insn
) == INSN
2625 && (set
= single_set (insn
)) != 0
2626 && ((reg
= SET_DEST (set
), GET_CODE (reg
) == REG
)
2627 || (GET_CODE (reg
) == SUBREG
2628 && (reg
= SUBREG_REG (reg
), GET_CODE (reg
) == REG
)))
2629 && REGNO (reg
) >= FIRST_PSEUDO_REGISTER
2630 && REGNO_FIRST_UID (REGNO (reg
)) == INSN_UID (insn
))
2632 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
2633 if (REGNO_LAST_UID (REGNO (reg
)) == INSN_UID (p
))
2638 /* We can do the replacement. Allocate reg_map if this is the
2639 first replacement we found. */
2642 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
2643 bzero ((char *) reg_map
, max_reg
* sizeof (rtx
));
2646 REG_LOOP_TEST_P (reg
) = 1;
2648 reg_map
[REGNO (reg
)] = gen_reg_rtx (GET_MODE (reg
));
2652 /* Now copy each insn. */
2653 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2654 switch (GET_CODE (insn
))
2657 copy
= emit_barrier_before (loop_start
);
2660 /* Only copy line-number notes. */
2661 if (NOTE_LINE_NUMBER (insn
) >= 0)
2663 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
2664 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
2669 copy
= emit_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2671 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2673 mark_jump_label (PATTERN (copy
), copy
, 0);
2675 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2677 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2678 if (REG_NOTE_KIND (link
) != REG_LABEL
)
2680 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link
),
2683 if (reg_map
&& REG_NOTES (copy
))
2684 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2688 copy
= emit_jump_insn_before (copy_rtx (PATTERN (insn
)), loop_start
);
2690 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2691 mark_jump_label (PATTERN (copy
), copy
, 0);
2692 if (REG_NOTES (insn
))
2694 REG_NOTES (copy
) = copy_rtx (REG_NOTES (insn
));
2696 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2699 /* If this is a simple jump, add it to the jump chain. */
2701 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
2702 && simplejump_p (copy
))
2704 jump_chain
[INSN_UID (copy
)]
2705 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2706 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2714 /* Now clean up by emitting a jump to the end label and deleting the jump
2715 at the start of the loop. */
2716 if (! copy
|| GET_CODE (copy
) != BARRIER
)
2718 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
2720 mark_jump_label (PATTERN (copy
), copy
, 0);
2721 if (INSN_UID (copy
) < max_jump_chain
2722 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
2724 jump_chain
[INSN_UID (copy
)]
2725 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2726 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2728 emit_barrier_before (loop_start
);
2731 /* Mark the exit code as the virtual top of the converted loop. */
2732 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
2734 delete_insn (next_nonnote_insn (loop_start
));
2739 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2740 loop-end notes between START and END out before START. Assume that
2741 END is not such a note. START may be such a note. Returns the value
2742 of the new starting insn, which may be different if the original start
2746 squeeze_notes (start
, end
)
2752 for (insn
= start
; insn
!= end
; insn
= next
)
2754 next
= NEXT_INSN (insn
);
2755 if (GET_CODE (insn
) == NOTE
2756 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2757 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2758 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2759 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
2760 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
2761 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
2767 rtx prev
= PREV_INSN (insn
);
2768 PREV_INSN (insn
) = PREV_INSN (start
);
2769 NEXT_INSN (insn
) = start
;
2770 NEXT_INSN (PREV_INSN (insn
)) = insn
;
2771 PREV_INSN (NEXT_INSN (insn
)) = insn
;
2772 NEXT_INSN (prev
) = next
;
2773 PREV_INSN (next
) = prev
;
2781 /* Compare the instructions before insn E1 with those before E2
2782 to find an opportunity for cross jumping.
2783 (This means detecting identical sequences of insns followed by
2784 jumps to the same place, or followed by a label and a jump
2785 to that label, and replacing one with a jump to the other.)
2787 Assume E1 is a jump that jumps to label E2
2788 (that is not always true but it might as well be).
2789 Find the longest possible equivalent sequences
2790 and store the first insns of those sequences into *F1 and *F2.
2791 Store zero there if no equivalent preceding instructions are found.
2793 We give up if we find a label in stream 1.
2794 Actually we could transfer that label into stream 2. */
2797 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
2802 register rtx i1
= e1
, i2
= e2
;
2803 register rtx p1
, p2
;
2806 rtx last1
= 0, last2
= 0;
2807 rtx afterlast1
= 0, afterlast2
= 0;
2814 i1
= prev_nonnote_insn (i1
);
2816 i2
= PREV_INSN (i2
);
2817 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
2818 i2
= PREV_INSN (i2
);
2823 /* Don't allow the range of insns preceding E1 or E2
2824 to include the other (E2 or E1). */
2825 if (i2
== e1
|| i1
== e2
)
2828 /* If we will get to this code by jumping, those jumps will be
2829 tensioned to go directly to the new label (before I2),
2830 so this cross-jumping won't cost extra. So reduce the minimum. */
2831 if (GET_CODE (i1
) == CODE_LABEL
)
2837 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
2840 /* Avoid moving insns across EH regions if either of the insns
2843 && (asynchronous_exceptions
|| GET_CODE (i1
) == CALL_INSN
)
2844 && !in_same_eh_region (i1
, i2
))
2850 /* If this is a CALL_INSN, compare register usage information.
2851 If we don't check this on stack register machines, the two
2852 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2853 numbers of stack registers in the same basic block.
2854 If we don't check this on machines with delay slots, a delay slot may
2855 be filled that clobbers a parameter expected by the subroutine.
2857 ??? We take the simple route for now and assume that if they're
2858 equal, they were constructed identically. */
2860 if (GET_CODE (i1
) == CALL_INSN
2861 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1
),
2862 CALL_INSN_FUNCTION_USAGE (i2
)))
2866 /* If cross_jump_death_matters is not 0, the insn's mode
2867 indicates whether or not the insn contains any stack-like
2870 if (!lose
&& cross_jump_death_matters
&& GET_MODE (i1
) == QImode
)
2872 /* If register stack conversion has already been done, then
2873 death notes must also be compared before it is certain that
2874 the two instruction streams match. */
2877 HARD_REG_SET i1_regset
, i2_regset
;
2879 CLEAR_HARD_REG_SET (i1_regset
);
2880 CLEAR_HARD_REG_SET (i2_regset
);
2882 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
2883 if (REG_NOTE_KIND (note
) == REG_DEAD
2884 && STACK_REG_P (XEXP (note
, 0)))
2885 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
2887 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
2888 if (REG_NOTE_KIND (note
) == REG_DEAD
2889 && STACK_REG_P (XEXP (note
, 0)))
2890 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
2892 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
2901 /* Don't allow old-style asm or volatile extended asms to be accepted
2902 for cross jumping purposes. It is conceptually correct to allow
2903 them, since cross-jumping preserves the dynamic instruction order
2904 even though it is changing the static instruction order. However,
2905 if an asm is being used to emit an assembler pseudo-op, such as
2906 the MIPS `.set reorder' pseudo-op, then the static instruction order
2907 matters and it must be preserved. */
2908 if (GET_CODE (p1
) == ASM_INPUT
|| GET_CODE (p2
) == ASM_INPUT
2909 || (GET_CODE (p1
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p1
))
2910 || (GET_CODE (p2
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p2
)))
2913 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
2914 || ! rtx_renumbered_equal_p (p1
, p2
))
2916 /* The following code helps take care of G++ cleanups. */
2920 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
2921 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
2922 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
2923 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
2924 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
2925 /* If the equivalences are not to a constant, they may
2926 reference pseudos that no longer exist, so we can't
2928 && CONSTANT_P (XEXP (equiv1
, 0))
2929 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
2931 rtx s1
= single_set (i1
);
2932 rtx s2
= single_set (i2
);
2933 if (s1
!= 0 && s2
!= 0
2934 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
2936 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
2937 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
2938 if (! rtx_renumbered_equal_p (p1
, p2
))
2940 else if (apply_change_group ())
2945 /* Insns fail to match; cross jumping is limited to the following
2949 /* Don't allow the insn after a compare to be shared by
2950 cross-jumping unless the compare is also shared.
2951 Here, if either of these non-matching insns is a compare,
2952 exclude the following insn from possible cross-jumping. */
2953 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
2954 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
2957 /* If cross-jumping here will feed a jump-around-jump
2958 optimization, this jump won't cost extra, so reduce
2960 if (GET_CODE (i1
) == JUMP_INSN
2962 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
2968 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
2970 /* Ok, this insn is potentially includable in a cross-jump here. */
2971 afterlast1
= last1
, afterlast2
= last2
;
2972 last1
= i1
, last2
= i2
, --minimum
;
2976 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
2977 *f1
= last1
, *f2
= last2
;
2981 do_cross_jump (insn
, newjpos
, newlpos
)
2982 rtx insn
, newjpos
, newlpos
;
2984 /* Find an existing label at this point
2985 or make a new one if there is none. */
2986 register rtx label
= get_label_before (newlpos
);
2988 /* Make the same jump insn jump to the new point. */
2989 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2991 /* Remove from jump chain of returns. */
2992 delete_from_jump_chain (insn
);
2993 /* Change the insn. */
2994 PATTERN (insn
) = gen_jump (label
);
2995 INSN_CODE (insn
) = -1;
2996 JUMP_LABEL (insn
) = label
;
2997 LABEL_NUSES (label
)++;
2998 /* Add to new the jump chain. */
2999 if (INSN_UID (label
) < max_jump_chain
3000 && INSN_UID (insn
) < max_jump_chain
)
3002 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
3003 jump_chain
[INSN_UID (label
)] = insn
;
3007 redirect_jump (insn
, label
);
3009 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
3010 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
3011 the NEWJPOS stream. */
3013 while (newjpos
!= insn
)
3017 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
3018 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
3019 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
3020 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
3021 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
3022 remove_note (newlpos
, lnote
);
3024 delete_insn (newjpos
);
3025 newjpos
= next_real_insn (newjpos
);
3026 newlpos
= next_real_insn (newlpos
);
3030 /* Return the label before INSN, or put a new label there. */
3033 get_label_before (insn
)
3038 /* Find an existing label at this point
3039 or make a new one if there is none. */
3040 label
= prev_nonnote_insn (insn
);
3042 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
3044 rtx prev
= PREV_INSN (insn
);
3046 label
= gen_label_rtx ();
3047 emit_label_after (label
, prev
);
3048 LABEL_NUSES (label
) = 0;
3053 /* Return the label after INSN, or put a new label there. */
3056 get_label_after (insn
)
3061 /* Find an existing label at this point
3062 or make a new one if there is none. */
3063 label
= next_nonnote_insn (insn
);
3065 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
3067 label
= gen_label_rtx ();
3068 emit_label_after (label
, insn
);
3069 LABEL_NUSES (label
) = 0;
3074 /* Return 1 if INSN is a jump that jumps to right after TARGET
3075 only on the condition that TARGET itself would drop through.
3076 Assumes that TARGET is a conditional jump. */
3079 jump_back_p (insn
, target
)
3083 enum rtx_code codei
, codet
;
3085 if (simplejump_p (insn
) || ! condjump_p (insn
)
3086 || simplejump_p (target
)
3087 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
3090 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
3091 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
3093 codei
= GET_CODE (cinsn
);
3094 codet
= GET_CODE (ctarget
);
3096 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
3098 if (! can_reverse_comparison_p (cinsn
, insn
))
3100 codei
= reverse_condition (codei
);
3103 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
3105 if (! can_reverse_comparison_p (ctarget
, target
))
3107 codet
= reverse_condition (codet
);
3110 return (codei
== codet
3111 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
3112 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
3115 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3116 return non-zero if it is safe to reverse this comparison. It is if our
3117 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3118 this is known to be an integer comparison. */
3121 can_reverse_comparison_p (comparison
, insn
)
3127 /* If this is not actually a comparison, we can't reverse it. */
3128 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
3131 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
3132 /* If this is an NE comparison, it is safe to reverse it to an EQ
3133 comparison and vice versa, even for floating point. If no operands
3134 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3135 always false and NE is always true, so the reversal is also valid. */
3137 || GET_CODE (comparison
) == NE
3138 || GET_CODE (comparison
) == EQ
)
3141 arg0
= XEXP (comparison
, 0);
3143 /* Make sure ARG0 is one of the actual objects being compared. If we
3144 can't do this, we can't be sure the comparison can be reversed.
3146 Handle cc0 and a MODE_CC register. */
3147 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
3153 rtx prev
= prev_nonnote_insn (insn
);
3154 rtx set
= single_set (prev
);
3156 if (set
== 0 || SET_DEST (set
) != arg0
)
3159 arg0
= SET_SRC (set
);
3161 if (GET_CODE (arg0
) == COMPARE
)
3162 arg0
= XEXP (arg0
, 0);
3165 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3166 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3167 return (GET_CODE (arg0
) == CONST_INT
3168 || (GET_MODE (arg0
) != VOIDmode
3169 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
3170 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
3173 /* Given an rtx-code for a comparison, return the code
3174 for the negated comparison.
3175 WATCH OUT! reverse_condition is not safe to use on a jump
3176 that might be acting on the results of an IEEE floating point comparison,
3177 because of the special treatment of non-signaling nans in comparisons.
3178 Use can_reverse_comparison_p to be sure. */
3181 reverse_condition (code
)
3222 /* Similar, but return the code when two operands of a comparison are swapped.
3223 This IS safe for IEEE floating-point. */
3226 swap_condition (code
)
3265 /* Given a comparison CODE, return the corresponding unsigned comparison.
3266 If CODE is an equality comparison or already an unsigned comparison,
3267 CODE is returned. */
3270 unsigned_condition (code
)
3300 /* Similarly, return the signed version of a comparison. */
3303 signed_condition (code
)
3333 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3334 truth of CODE1 implies the truth of CODE2. */
3337 comparison_dominates_p (code1
, code2
)
3338 enum rtx_code code1
, code2
;
3346 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
3351 if (code2
== LE
|| code2
== NE
)
3356 if (code2
== GE
|| code2
== NE
)
3361 if (code2
== LEU
|| code2
== NE
)
3366 if (code2
== GEU
|| code2
== NE
)
3377 /* Return 1 if INSN is an unconditional jump and nothing else. */
3383 return (GET_CODE (insn
) == JUMP_INSN
3384 && GET_CODE (PATTERN (insn
)) == SET
3385 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
3386 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
3389 /* Return nonzero if INSN is a (possibly) conditional jump
3390 and nothing more. */
3396 register rtx x
= PATTERN (insn
);
3397 if (GET_CODE (x
) != SET
)
3399 if (GET_CODE (SET_DEST (x
)) != PC
)
3401 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
3403 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
3405 if (XEXP (SET_SRC (x
), 2) == pc_rtx
3406 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
3407 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
3409 if (XEXP (SET_SRC (x
), 1) == pc_rtx
3410 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
3411 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
3416 /* Return nonzero if INSN is a (possibly) conditional jump
3417 and nothing more. */
3420 condjump_in_parallel_p (insn
)
3423 register rtx x
= PATTERN (insn
);
3425 if (GET_CODE (x
) != PARALLEL
)
3428 x
= XVECEXP (x
, 0, 0);
3430 if (GET_CODE (x
) != SET
)
3432 if (GET_CODE (SET_DEST (x
)) != PC
)
3434 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
3436 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
3438 if (XEXP (SET_SRC (x
), 2) == pc_rtx
3439 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
3440 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
3442 if (XEXP (SET_SRC (x
), 1) == pc_rtx
3443 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
3444 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
3449 /* Return the label of a conditional jump. */
3452 condjump_label (insn
)
3455 register rtx x
= PATTERN (insn
);
3457 if (GET_CODE (x
) == PARALLEL
)
3458 x
= XVECEXP (x
, 0, 0);
3459 if (GET_CODE (x
) != SET
)
3461 if (GET_CODE (SET_DEST (x
)) != PC
)
3464 if (GET_CODE (x
) == LABEL_REF
)
3466 if (GET_CODE (x
) != IF_THEN_ELSE
)
3468 if (XEXP (x
, 2) == pc_rtx
&& GET_CODE (XEXP (x
, 1)) == LABEL_REF
)
3470 if (XEXP (x
, 1) == pc_rtx
&& GET_CODE (XEXP (x
, 2)) == LABEL_REF
)
3475 /* Return true if INSN is a (possibly conditional) return insn. */
3478 returnjump_p_1 (loc
, data
)
3480 void *data ATTRIBUTE_UNUSED
;
3483 return GET_CODE (x
) == RETURN
;
3490 return for_each_rtx (&PATTERN (insn
), returnjump_p_1
, NULL
);
3495 /* Return 1 if X is an RTX that does nothing but set the condition codes
3496 and CLOBBER or USE registers.
3497 Return -1 if X does explicitly set the condition codes,
3498 but also does other things. */
3502 rtx x ATTRIBUTE_UNUSED
;
3504 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
3506 if (GET_CODE (x
) == PARALLEL
)
3510 int other_things
= 0;
3511 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
3513 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
3514 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
3516 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
3519 return ! sets_cc0
? 0 : other_things
? -1 : 1;
3525 /* Follow any unconditional jump at LABEL;
3526 return the ultimate label reached by any such chain of jumps.
3527 If LABEL is not followed by a jump, return LABEL.
3528 If the chain loops or we can't find end, return LABEL,
3529 since that tells caller to avoid changing the insn.
3531 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3532 a USE or CLOBBER. */
3535 follow_jumps (label
)
3540 register rtx value
= label
;
3545 && (insn
= next_active_insn (value
)) != 0
3546 && GET_CODE (insn
) == JUMP_INSN
3547 && ((JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
3548 || GET_CODE (PATTERN (insn
)) == RETURN
)
3549 && (next
= NEXT_INSN (insn
))
3550 && GET_CODE (next
) == BARRIER
);
3553 /* Don't chain through the insn that jumps into a loop
3554 from outside the loop,
3555 since that would create multiple loop entry jumps
3556 and prevent loop optimization. */
3558 if (!reload_completed
)
3559 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
3560 if (GET_CODE (tem
) == NOTE
3561 && (NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
3562 /* ??? Optional. Disables some optimizations, but makes
3563 gcov output more accurate with -O. */
3564 || (flag_test_coverage
&& NOTE_LINE_NUMBER (tem
) > 0)))
3567 /* If we have found a cycle, make the insn jump to itself. */
3568 if (JUMP_LABEL (insn
) == label
)
3571 tem
= next_active_insn (JUMP_LABEL (insn
));
3572 if (tem
&& (GET_CODE (PATTERN (tem
)) == ADDR_VEC
3573 || GET_CODE (PATTERN (tem
)) == ADDR_DIFF_VEC
))
3576 value
= JUMP_LABEL (insn
);
3583 /* Assuming that field IDX of X is a vector of label_refs,
3584 replace each of them by the ultimate label reached by it.
3585 Return nonzero if a change is made.
3586 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3589 tension_vector_labels (x
, idx
)
3595 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
3597 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
3598 register rtx nlabel
= follow_jumps (olabel
);
3599 if (nlabel
&& nlabel
!= olabel
)
3601 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
3602 ++LABEL_NUSES (nlabel
);
3603 if (--LABEL_NUSES (olabel
) == 0)
3604 delete_insn (olabel
);
3611 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3612 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3613 in INSN, then store one of them in JUMP_LABEL (INSN).
3614 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3615 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3616 Also, when there are consecutive labels, canonicalize on the last of them.
3618 Note that two labels separated by a loop-beginning note
3619 must be kept distinct if we have not yet done loop-optimization,
3620 because the gap between them is where loop-optimize
3621 will want to move invariant code to. CROSS_JUMP tells us
3622 that loop-optimization is done with.
3624 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3625 two labels distinct if they are separated by only USE or CLOBBER insns. */
3628 mark_jump_label (x
, insn
, cross_jump
)
3633 register RTX_CODE code
= GET_CODE (x
);
3651 /* If this is a constant-pool reference, see if it is a label. */
3652 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3653 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3654 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
3659 rtx label
= XEXP (x
, 0);
3664 if (GET_CODE (label
) != CODE_LABEL
)
3667 /* Ignore references to labels of containing functions. */
3668 if (LABEL_REF_NONLOCAL_P (x
))
3671 /* If there are other labels following this one,
3672 replace it with the last of the consecutive labels. */
3673 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
3675 if (GET_CODE (next
) == CODE_LABEL
)
3677 else if (cross_jump
&& GET_CODE (next
) == INSN
3678 && (GET_CODE (PATTERN (next
)) == USE
3679 || GET_CODE (PATTERN (next
)) == CLOBBER
))
3681 else if (GET_CODE (next
) != NOTE
)
3683 else if (! cross_jump
3684 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
3685 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
3686 /* ??? Optional. Disables some optimizations, but
3687 makes gcov output more accurate with -O. */
3688 || (flag_test_coverage
&& NOTE_LINE_NUMBER (next
) > 0)))
3692 XEXP (x
, 0) = label
;
3693 if (! insn
|| ! INSN_DELETED_P (insn
))
3694 ++LABEL_NUSES (label
);
3698 if (GET_CODE (insn
) == JUMP_INSN
)
3699 JUMP_LABEL (insn
) = label
;
3701 /* If we've changed OLABEL and we had a REG_LABEL note
3702 for it, update it as well. */
3703 else if (label
!= olabel
3704 && (note
= find_reg_note (insn
, REG_LABEL
, olabel
)) != 0)
3705 XEXP (note
, 0) = label
;
3707 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3709 else if (! find_reg_note (insn
, REG_LABEL
, label
))
3711 /* This code used to ignore labels which refered to dispatch
3712 tables to avoid flow.c generating worse code.
3714 However, in the presense of global optimizations like
3715 gcse which call find_basic_blocks without calling
3716 life_analysis, not recording such labels will lead
3717 to compiler aborts because of inconsistencies in the
3718 flow graph. So we go ahead and record the label.
3720 It may also be the case that the optimization argument
3721 is no longer valid because of the more accurate cfg
3722 we build in find_basic_blocks -- it no longer pessimizes
3723 code when it finds a REG_LABEL note. */
3724 REG_NOTES (insn
) = gen_rtx_EXPR_LIST (REG_LABEL
, label
,
3731 /* Do walk the labels in a vector, but not the first operand of an
3732 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3735 if (! INSN_DELETED_P (insn
))
3737 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
3739 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
3740 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
, cross_jump
);
3748 fmt
= GET_RTX_FORMAT (code
);
3749 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3752 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
3753 else if (fmt
[i
] == 'E')
3756 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3757 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
3762 /* If all INSN does is set the pc, delete it,
3763 and delete the insn that set the condition codes for it
3764 if that's what the previous thing was. */
3770 register rtx set
= single_set (insn
);
3772 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
3773 delete_computation (insn
);
3776 /* Delete INSN and recursively delete insns that compute values used only
3777 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3778 If we are running before flow.c, we need do nothing since flow.c will
3779 delete dead code. We also can't know if the registers being used are
3780 dead or not at this point.
3782 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3783 nothing other than set a register that dies in this insn, we can delete
3786 On machines with CC0, if CC0 is used in this insn, we may be able to
3787 delete the insn that set it. */
3790 delete_computation (insn
)
3796 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
3798 rtx prev
= prev_nonnote_insn (insn
);
3799 /* We assume that at this stage
3800 CC's are always set explicitly
3801 and always immediately before the jump that
3802 will use them. So if the previous insn
3803 exists to set the CC's, delete it
3804 (unless it performs auto-increments, etc.). */
3805 if (prev
&& GET_CODE (prev
) == INSN
3806 && sets_cc0_p (PATTERN (prev
)))
3808 if (sets_cc0_p (PATTERN (prev
)) > 0
3809 && !FIND_REG_INC_NOTE (prev
, NULL_RTX
))
3810 delete_computation (prev
);
3812 /* Otherwise, show that cc0 won't be used. */
3813 REG_NOTES (prev
) = gen_rtx_EXPR_LIST (REG_UNUSED
,
3814 cc0_rtx
, REG_NOTES (prev
));
3819 #ifdef INSN_SCHEDULING
3820 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
3821 reload has completed. The schedulers need to be fixed. Until
3822 they are, we must not rely on the death notes here. */
3823 if (reload_completed
&& flag_schedule_insns_after_reload
)
3830 for (note
= REG_NOTES (insn
); note
; note
= next
)
3834 next
= XEXP (note
, 1);
3836 if (REG_NOTE_KIND (note
) != REG_DEAD
3837 /* Verify that the REG_NOTE is legitimate. */
3838 || GET_CODE (XEXP (note
, 0)) != REG
)
3841 for (our_prev
= prev_nonnote_insn (insn
);
3842 our_prev
&& GET_CODE (our_prev
) == INSN
;
3843 our_prev
= prev_nonnote_insn (our_prev
))
3845 /* If we reach a SEQUENCE, it is too complex to try to
3846 do anything with it, so give up. */
3847 if (GET_CODE (PATTERN (our_prev
)) == SEQUENCE
)
3850 if (GET_CODE (PATTERN (our_prev
)) == USE
3851 && GET_CODE (XEXP (PATTERN (our_prev
), 0)) == INSN
)
3852 /* reorg creates USEs that look like this. We leave them
3853 alone because reorg needs them for its own purposes. */
3856 if (reg_set_p (XEXP (note
, 0), PATTERN (our_prev
)))
3858 if (FIND_REG_INC_NOTE (our_prev
, NULL_RTX
))
3861 if (GET_CODE (PATTERN (our_prev
)) == PARALLEL
)
3863 /* If we find a SET of something else, we can't
3868 for (i
= 0; i
< XVECLEN (PATTERN (our_prev
), 0); i
++)
3870 rtx part
= XVECEXP (PATTERN (our_prev
), 0, i
);
3872 if (GET_CODE (part
) == SET
3873 && SET_DEST (part
) != XEXP (note
, 0))
3877 if (i
== XVECLEN (PATTERN (our_prev
), 0))
3878 delete_computation (our_prev
);
3880 else if (GET_CODE (PATTERN (our_prev
)) == SET
3881 && SET_DEST (PATTERN (our_prev
)) == XEXP (note
, 0))
3882 delete_computation (our_prev
);
3887 /* If OUR_PREV references the register that dies here, it is an
3888 additional use. Hence any prior SET isn't dead. However, this
3889 insn becomes the new place for the REG_DEAD note. */
3890 if (reg_overlap_mentioned_p (XEXP (note
, 0),
3891 PATTERN (our_prev
)))
3893 XEXP (note
, 1) = REG_NOTES (our_prev
);
3894 REG_NOTES (our_prev
) = note
;
3903 /* Delete insn INSN from the chain of insns and update label ref counts.
3904 May delete some following insns as a consequence; may even delete
3905 a label elsewhere and insns that follow it.
3907 Returns the first insn after INSN that was not deleted. */
3913 register rtx next
= NEXT_INSN (insn
);
3914 register rtx prev
= PREV_INSN (insn
);
3915 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
3916 register int dont_really_delete
= 0;
3918 while (next
&& INSN_DELETED_P (next
))
3919 next
= NEXT_INSN (next
);
3921 /* This insn is already deleted => return first following nondeleted. */
3922 if (INSN_DELETED_P (insn
))
3925 /* Don't delete user-declared labels. Convert them to special NOTEs
3927 if (was_code_label
&& LABEL_NAME (insn
) != 0
3928 && optimize
&& ! dont_really_delete
)
3930 PUT_CODE (insn
, NOTE
);
3931 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
3932 NOTE_SOURCE_FILE (insn
) = 0;
3933 dont_really_delete
= 1;
3936 /* Mark this insn as deleted. */
3937 INSN_DELETED_P (insn
) = 1;
3939 /* If this is an unconditional jump, delete it from the jump chain. */
3940 if (simplejump_p (insn
))
3941 delete_from_jump_chain (insn
);
3943 /* If instruction is followed by a barrier,
3944 delete the barrier too. */
3946 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
3948 INSN_DELETED_P (next
) = 1;
3949 next
= NEXT_INSN (next
);
3952 /* Patch out INSN (and the barrier if any) */
3954 if (optimize
&& ! dont_really_delete
)
3958 NEXT_INSN (prev
) = next
;
3959 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
3960 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
3961 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
3966 PREV_INSN (next
) = prev
;
3967 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
3968 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
3971 if (prev
&& NEXT_INSN (prev
) == 0)
3972 set_last_insn (prev
);
3975 /* If deleting a jump, decrement the count of the label,
3976 and delete the label if it is now unused. */
3978 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
3979 if (--LABEL_NUSES (JUMP_LABEL (insn
)) == 0)
3981 /* This can delete NEXT or PREV,
3982 either directly if NEXT is JUMP_LABEL (INSN),
3983 or indirectly through more levels of jumps. */
3984 delete_insn (JUMP_LABEL (insn
));
3985 /* I feel a little doubtful about this loop,
3986 but I see no clean and sure alternative way
3987 to find the first insn after INSN that is not now deleted.
3988 I hope this works. */
3989 while (next
&& INSN_DELETED_P (next
))
3990 next
= NEXT_INSN (next
);
3994 /* Likewise if we're deleting a dispatch table. */
3996 if (GET_CODE (insn
) == JUMP_INSN
3997 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
3998 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
4000 rtx pat
= PATTERN (insn
);
4001 int i
, diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
4002 int len
= XVECLEN (pat
, diff_vec_p
);
4004 for (i
= 0; i
< len
; i
++)
4005 if (--LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)) == 0)
4006 delete_insn (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0));
4007 while (next
&& INSN_DELETED_P (next
))
4008 next
= NEXT_INSN (next
);
4012 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
4013 prev
= PREV_INSN (prev
);
4015 /* If INSN was a label and a dispatch table follows it,
4016 delete the dispatch table. The tablejump must have gone already.
4017 It isn't useful to fall through into a table. */
4020 && NEXT_INSN (insn
) != 0
4021 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
4022 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
4023 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
4024 next
= delete_insn (NEXT_INSN (insn
));
4026 /* If INSN was a label, delete insns following it if now unreachable. */
4028 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
4030 register RTX_CODE code
;
4032 && (GET_RTX_CLASS (code
= GET_CODE (next
)) == 'i'
4033 || code
== NOTE
|| code
== BARRIER
4034 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
4037 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
4038 next
= NEXT_INSN (next
);
4039 /* Keep going past other deleted labels to delete what follows. */
4040 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
4041 next
= NEXT_INSN (next
);
4043 /* Note: if this deletes a jump, it can cause more
4044 deletion of unreachable code, after a different label.
4045 As long as the value from this recursive call is correct,
4046 this invocation functions correctly. */
4047 next
= delete_insn (next
);
4054 /* Advance from INSN till reaching something not deleted
4055 then return that. May return INSN itself. */
4058 next_nondeleted_insn (insn
)
4061 while (INSN_DELETED_P (insn
))
4062 insn
= NEXT_INSN (insn
);
4066 /* Delete a range of insns from FROM to TO, inclusive.
4067 This is for the sake of peephole optimization, so assume
4068 that whatever these insns do will still be done by a new
4069 peephole insn that will replace them. */
4072 delete_for_peephole (from
, to
)
4073 register rtx from
, to
;
4075 register rtx insn
= from
;
4079 register rtx next
= NEXT_INSN (insn
);
4080 register rtx prev
= PREV_INSN (insn
);
4082 if (GET_CODE (insn
) != NOTE
)
4084 INSN_DELETED_P (insn
) = 1;
4086 /* Patch this insn out of the chain. */
4087 /* We don't do this all at once, because we
4088 must preserve all NOTEs. */
4090 NEXT_INSN (prev
) = next
;
4093 PREV_INSN (next
) = prev
;
4101 /* Note that if TO is an unconditional jump
4102 we *do not* delete the BARRIER that follows,
4103 since the peephole that replaces this sequence
4104 is also an unconditional jump in that case. */
4107 /* Invert the condition of the jump JUMP, and make it jump
4108 to label NLABEL instead of where it jumps now. */
4111 invert_jump (jump
, nlabel
)
4114 /* We have to either invert the condition and change the label or
4115 do neither. Either operation could fail. We first try to invert
4116 the jump. If that succeeds, we try changing the label. If that fails,
4117 we invert the jump back to what it was. */
4119 if (! invert_exp (PATTERN (jump
), jump
))
4122 if (redirect_jump (jump
, nlabel
))
4124 if (flag_branch_probabilities
)
4126 rtx note
= find_reg_note (jump
, REG_BR_PROB
, 0);
4128 /* An inverted jump means that a probability taken becomes a
4129 probability not taken. Subtract the branch probability from the
4130 probability base to convert it back to a taken probability.
4131 (We don't flip the probability on a branch that's never taken. */
4132 if (note
&& XINT (XEXP (note
, 0), 0) >= 0)
4133 XINT (XEXP (note
, 0), 0) = REG_BR_PROB_BASE
- XINT (XEXP (note
, 0), 0);
4139 if (! invert_exp (PATTERN (jump
), jump
))
4140 /* This should just be putting it back the way it was. */
4146 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4148 Return 1 if we can do so, 0 if we cannot find a way to do so that
4149 matches a pattern. */
4152 invert_exp (x
, insn
)
4156 register RTX_CODE code
;
4160 code
= GET_CODE (x
);
4162 if (code
== IF_THEN_ELSE
)
4164 register rtx comp
= XEXP (x
, 0);
4167 /* We can do this in two ways: The preferable way, which can only
4168 be done if this is not an integer comparison, is to reverse
4169 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4170 of the IF_THEN_ELSE. If we can't do either, fail. */
4172 if (can_reverse_comparison_p (comp
, insn
)
4173 && validate_change (insn
, &XEXP (x
, 0),
4174 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp
)),
4175 GET_MODE (comp
), XEXP (comp
, 0),
4176 XEXP (comp
, 1)), 0))
4180 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
4181 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
4182 return apply_change_group ();
4185 fmt
= GET_RTX_FORMAT (code
);
4186 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4189 if (! invert_exp (XEXP (x
, i
), insn
))
4194 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4195 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
4203 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4204 If the old jump target label is unused as a result,
4205 it and the code following it may be deleted.
4207 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4210 The return value will be 1 if the change was made, 0 if it wasn't (this
4211 can only occur for NLABEL == 0). */
4214 redirect_jump (jump
, nlabel
)
4217 register rtx olabel
= JUMP_LABEL (jump
);
4219 if (nlabel
== olabel
)
4222 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
4225 /* If this is an unconditional branch, delete it from the jump_chain of
4226 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4227 have UID's in range and JUMP_CHAIN is valid). */
4228 if (jump_chain
&& (simplejump_p (jump
)
4229 || GET_CODE (PATTERN (jump
)) == RETURN
))
4231 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
4233 delete_from_jump_chain (jump
);
4234 if (label_index
< max_jump_chain
4235 && INSN_UID (jump
) < max_jump_chain
)
4237 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
4238 jump_chain
[label_index
] = jump
;
4242 JUMP_LABEL (jump
) = nlabel
;
4244 ++LABEL_NUSES (nlabel
);
4246 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
4247 delete_insn (olabel
);
4252 /* Delete the instruction JUMP from any jump chain it might be on. */
4255 delete_from_jump_chain (jump
)
4259 rtx olabel
= JUMP_LABEL (jump
);
4261 /* Handle unconditional jumps. */
4262 if (jump_chain
&& olabel
!= 0
4263 && INSN_UID (olabel
) < max_jump_chain
4264 && simplejump_p (jump
))
4265 index
= INSN_UID (olabel
);
4266 /* Handle return insns. */
4267 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
4271 if (jump_chain
[index
] == jump
)
4272 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
4277 for (insn
= jump_chain
[index
];
4279 insn
= jump_chain
[INSN_UID (insn
)])
4280 if (jump_chain
[INSN_UID (insn
)] == jump
)
4282 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
4288 /* If NLABEL is nonzero, throughout the rtx at LOC,
4289 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4290 zero, alter (RETURN) to (LABEL_REF NLABEL).
4292 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4293 validity with validate_change. Convert (set (pc) (label_ref olabel))
4296 Return 0 if we found a change we would like to make but it is invalid.
4297 Otherwise, return 1. */
4300 redirect_exp (loc
, olabel
, nlabel
, insn
)
4305 register rtx x
= *loc
;
4306 register RTX_CODE code
= GET_CODE (x
);
4310 if (code
== LABEL_REF
)
4312 if (XEXP (x
, 0) == olabel
)
4315 XEXP (x
, 0) = nlabel
;
4317 return validate_change (insn
, loc
, gen_rtx_RETURN (VOIDmode
), 0);
4321 else if (code
== RETURN
&& olabel
== 0)
4323 x
= gen_rtx_LABEL_REF (VOIDmode
, nlabel
);
4324 if (loc
== &PATTERN (insn
))
4325 x
= gen_rtx_SET (VOIDmode
, pc_rtx
, x
);
4326 return validate_change (insn
, loc
, x
, 0);
4329 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
4330 && GET_CODE (SET_SRC (x
)) == LABEL_REF
4331 && XEXP (SET_SRC (x
), 0) == olabel
)
4332 return validate_change (insn
, loc
, gen_rtx_RETURN (VOIDmode
), 0);
4334 fmt
= GET_RTX_FORMAT (code
);
4335 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4338 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
4343 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4344 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
4352 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4354 If the old jump target label (before the dispatch table) becomes unused,
4355 it and the dispatch table may be deleted. In that case, find the insn
4356 before the jump references that label and delete it and logical successors
4360 redirect_tablejump (jump
, nlabel
)
4363 register rtx olabel
= JUMP_LABEL (jump
);
4365 /* Add this jump to the jump_chain of NLABEL. */
4366 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
4367 && INSN_UID (jump
) < max_jump_chain
)
4369 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
4370 jump_chain
[INSN_UID (nlabel
)] = jump
;
4373 PATTERN (jump
) = gen_jump (nlabel
);
4374 JUMP_LABEL (jump
) = nlabel
;
4375 ++LABEL_NUSES (nlabel
);
4376 INSN_CODE (jump
) = -1;
4378 if (--LABEL_NUSES (olabel
) == 0)
4380 delete_labelref_insn (jump
, olabel
, 0);
4381 delete_insn (olabel
);
4385 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4386 If we found one, delete it and then delete this insn if DELETE_THIS is
4387 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4390 delete_labelref_insn (insn
, label
, delete_this
)
4397 if (GET_CODE (insn
) != NOTE
4398 && reg_mentioned_p (label
, PATTERN (insn
)))
4409 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
4410 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
4424 /* Like rtx_equal_p except that it considers two REGs as equal
4425 if they renumber to the same value and considers two commutative
4426 operations to be the same if the order of the operands has been
4429 ??? Addition is not commutative on the PA due to the weird implicit
4430 space register selection rules for memory addresses. Therefore, we
4431 don't consider a + b == b + a.
4433 We could/should make this test a little tighter. Possibly only
4434 disabling it on the PA via some backend macro or only disabling this
4435 case when the PLUS is inside a MEM. */
4438 rtx_renumbered_equal_p (x
, y
)
4442 register RTX_CODE code
= GET_CODE (x
);
4448 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
4449 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
4450 && GET_CODE (SUBREG_REG (y
)) == REG
)))
4452 int reg_x
= -1, reg_y
= -1;
4453 int word_x
= 0, word_y
= 0;
4455 if (GET_MODE (x
) != GET_MODE (y
))
4458 /* If we haven't done any renumbering, don't
4459 make any assumptions. */
4460 if (reg_renumber
== 0)
4461 return rtx_equal_p (x
, y
);
4465 reg_x
= REGNO (SUBREG_REG (x
));
4466 word_x
= SUBREG_WORD (x
);
4468 if (reg_renumber
[reg_x
] >= 0)
4470 reg_x
= reg_renumber
[reg_x
] + word_x
;
4478 if (reg_renumber
[reg_x
] >= 0)
4479 reg_x
= reg_renumber
[reg_x
];
4482 if (GET_CODE (y
) == SUBREG
)
4484 reg_y
= REGNO (SUBREG_REG (y
));
4485 word_y
= SUBREG_WORD (y
);
4487 if (reg_renumber
[reg_y
] >= 0)
4489 reg_y
= reg_renumber
[reg_y
];
4497 if (reg_renumber
[reg_y
] >= 0)
4498 reg_y
= reg_renumber
[reg_y
];
4501 return reg_x
>= 0 && reg_x
== reg_y
&& word_x
== word_y
;
4504 /* Now we have disposed of all the cases
4505 in which different rtx codes can match. */
4506 if (code
!= GET_CODE (y
))
4518 return INTVAL (x
) == INTVAL (y
);
4521 /* We can't assume nonlocal labels have their following insns yet. */
4522 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
4523 return XEXP (x
, 0) == XEXP (y
, 0);
4525 /* Two label-refs are equivalent if they point at labels
4526 in the same position in the instruction stream. */
4527 return (next_real_insn (XEXP (x
, 0))
4528 == next_real_insn (XEXP (y
, 0)));
4531 return XSTR (x
, 0) == XSTR (y
, 0);
4534 /* If we didn't match EQ equality above, they aren't the same. */
4541 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4543 if (GET_MODE (x
) != GET_MODE (y
))
4546 /* For commutative operations, the RTX match if the operand match in any
4547 order. Also handle the simple binary and unary cases without a loop.
4549 ??? Don't consider PLUS a commutative operator; see comments above. */
4550 if ((code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4552 return ((rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
4553 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)))
4554 || (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 1))
4555 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 0))));
4556 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4557 return (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
4558 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)));
4559 else if (GET_RTX_CLASS (code
) == '1')
4560 return rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0));
4562 /* Compare the elements. If any pair of corresponding elements
4563 fail to match, return 0 for the whole things. */
4565 fmt
= GET_RTX_FORMAT (code
);
4566 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4572 if (XWINT (x
, i
) != XWINT (y
, i
))
4577 if (XINT (x
, i
) != XINT (y
, i
))
4582 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4587 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
4592 if (XEXP (x
, i
) != XEXP (y
, i
))
4599 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
4601 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4602 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
4613 /* If X is a hard register or equivalent to one or a subregister of one,
4614 return the hard register number. If X is a pseudo register that was not
4615 assigned a hard register, return the pseudo register number. Otherwise,
4616 return -1. Any rtx is valid for X. */
4622 if (GET_CODE (x
) == REG
)
4624 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
4625 return reg_renumber
[REGNO (x
)];
4628 if (GET_CODE (x
) == SUBREG
)
4630 int base
= true_regnum (SUBREG_REG (x
));
4631 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
4632 return SUBREG_WORD (x
) + base
;
4637 /* Optimize code of the form:
4639 for (x = a[i]; x; ...)
4641 for (x = a[i]; x; ...)
4645 Loop optimize will change the above code into
4649 { ...; if (! (x = ...)) break; }
4652 { ...; if (! (x = ...)) break; }
4655 In general, if the first test fails, the program can branch
4656 directly to `foo' and skip the second try which is doomed to fail.
4657 We run this after loop optimization and before flow analysis. */
4659 /* When comparing the insn patterns, we track the fact that different
4660 pseudo-register numbers may have been used in each computation.
4661 The following array stores an equivalence -- same_regs[I] == J means
4662 that pseudo register I was used in the first set of tests in a context
4663 where J was used in the second set. We also count the number of such
4664 pending equivalences. If nonzero, the expressions really aren't the
4667 static int *same_regs
;
4669 static int num_same_regs
;
4671 /* Track any registers modified between the target of the first jump and
4672 the second jump. They never compare equal. */
4674 static char *modified_regs
;
4676 /* Record if memory was modified. */
4678 static int modified_mem
;
4680 /* Called via note_stores on each insn between the target of the first
4681 branch and the second branch. It marks any changed registers. */
4684 mark_modified_reg (dest
, x
)
4686 rtx x ATTRIBUTE_UNUSED
;
4690 if (GET_CODE (dest
) == SUBREG
)
4691 dest
= SUBREG_REG (dest
);
4693 if (GET_CODE (dest
) == MEM
)
4696 if (GET_CODE (dest
) != REG
)
4699 regno
= REGNO (dest
);
4700 if (regno
>= FIRST_PSEUDO_REGISTER
)
4701 modified_regs
[regno
] = 1;
4703 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
4704 modified_regs
[regno
+ i
] = 1;
4707 /* F is the first insn in the chain of insns. */
4710 thread_jumps (f
, max_reg
, flag_before_loop
)
4713 int flag_before_loop
;
4715 /* Basic algorithm is to find a conditional branch,
4716 the label it may branch to, and the branch after
4717 that label. If the two branches test the same condition,
4718 walk back from both branch paths until the insn patterns
4719 differ, or code labels are hit. If we make it back to
4720 the target of the first branch, then we know that the first branch
4721 will either always succeed or always fail depending on the relative
4722 senses of the two branches. So adjust the first branch accordingly
4725 rtx label
, b1
, b2
, t1
, t2
;
4726 enum rtx_code code1
, code2
;
4727 rtx b1op0
, b1op1
, b2op0
, b2op1
;
4732 /* Allocate register tables and quick-reset table. */
4733 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
4734 same_regs
= (int *) alloca (max_reg
* sizeof (int));
4735 all_reset
= (int *) alloca (max_reg
* sizeof (int));
4736 for (i
= 0; i
< max_reg
; i
++)
4743 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
4745 /* Get to a candidate branch insn. */
4746 if (GET_CODE (b1
) != JUMP_INSN
4747 || ! condjump_p (b1
) || simplejump_p (b1
)
4748 || JUMP_LABEL (b1
) == 0)
4751 bzero (modified_regs
, max_reg
* sizeof (char));
4754 bcopy ((char *) all_reset
, (char *) same_regs
,
4755 max_reg
* sizeof (int));
4758 label
= JUMP_LABEL (b1
);
4760 /* Look for a branch after the target. Record any registers and
4761 memory modified between the target and the branch. Stop when we
4762 get to a label since we can't know what was changed there. */
4763 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
4765 if (GET_CODE (b2
) == CODE_LABEL
)
4768 else if (GET_CODE (b2
) == JUMP_INSN
)
4770 /* If this is an unconditional jump and is the only use of
4771 its target label, we can follow it. */
4772 if (simplejump_p (b2
)
4773 && JUMP_LABEL (b2
) != 0
4774 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
4776 b2
= JUMP_LABEL (b2
);
4783 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
4786 if (GET_CODE (b2
) == CALL_INSN
)
4789 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
4790 if (call_used_regs
[i
] && ! fixed_regs
[i
]
4791 && i
!= STACK_POINTER_REGNUM
4792 && i
!= FRAME_POINTER_REGNUM
4793 && i
!= HARD_FRAME_POINTER_REGNUM
4794 && i
!= ARG_POINTER_REGNUM
)
4795 modified_regs
[i
] = 1;
4798 note_stores (PATTERN (b2
), mark_modified_reg
);
4801 /* Check the next candidate branch insn from the label
4804 || GET_CODE (b2
) != JUMP_INSN
4806 || ! condjump_p (b2
)
4807 || simplejump_p (b2
))
4810 /* Get the comparison codes and operands, reversing the
4811 codes if appropriate. If we don't have comparison codes,
4812 we can't do anything. */
4813 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
4814 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
4815 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
4816 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
4817 code1
= reverse_condition (code1
);
4819 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
4820 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
4821 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
4822 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
4823 code2
= reverse_condition (code2
);
4825 /* If they test the same things and knowing that B1 branches
4826 tells us whether or not B2 branches, check if we
4827 can thread the branch. */
4828 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
4829 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
4830 && (comparison_dominates_p (code1
, code2
)
4831 || (comparison_dominates_p (code1
, reverse_condition (code2
))
4832 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1
)),
4836 t1
= prev_nonnote_insn (b1
);
4837 t2
= prev_nonnote_insn (b2
);
4839 while (t1
!= 0 && t2
!= 0)
4843 /* We have reached the target of the first branch.
4844 If there are no pending register equivalents,
4845 we know that this branch will either always
4846 succeed (if the senses of the two branches are
4847 the same) or always fail (if not). */
4850 if (num_same_regs
!= 0)
4853 if (comparison_dominates_p (code1
, code2
))
4854 new_label
= JUMP_LABEL (b2
);
4856 new_label
= get_label_after (b2
);
4858 if (JUMP_LABEL (b1
) != new_label
)
4860 rtx prev
= PREV_INSN (new_label
);
4862 if (flag_before_loop
4863 && GET_CODE (prev
) == NOTE
4864 && NOTE_LINE_NUMBER (prev
) == NOTE_INSN_LOOP_BEG
)
4866 /* Don't thread to the loop label. If a loop
4867 label is reused, loop optimization will
4868 be disabled for that loop. */
4869 new_label
= gen_label_rtx ();
4870 emit_label_after (new_label
, PREV_INSN (prev
));
4872 changed
|= redirect_jump (b1
, new_label
);
4877 /* If either of these is not a normal insn (it might be
4878 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4879 have already been skipped above.) Similarly, fail
4880 if the insns are different. */
4881 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
4882 || recog_memoized (t1
) != recog_memoized (t2
)
4883 || ! rtx_equal_for_thread_p (PATTERN (t1
),
4887 t1
= prev_nonnote_insn (t1
);
4888 t2
= prev_nonnote_insn (t2
);
4895 /* This is like RTX_EQUAL_P except that it knows about our handling of
4896 possibly equivalent registers and knows to consider volatile and
4897 modified objects as not equal.
4899 YINSN is the insn containing Y. */
4902 rtx_equal_for_thread_p (x
, y
, yinsn
)
4908 register enum rtx_code code
;
4911 code
= GET_CODE (x
);
4912 /* Rtx's of different codes cannot be equal. */
4913 if (code
!= GET_CODE (y
))
4916 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4917 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4919 if (GET_MODE (x
) != GET_MODE (y
))
4922 /* For floating-point, consider everything unequal. This is a bit
4923 pessimistic, but this pass would only rarely do anything for FP
4925 if (TARGET_FLOAT_FORMAT
== IEEE_FLOAT_FORMAT
4926 && FLOAT_MODE_P (GET_MODE (x
)) && ! flag_fast_math
)
4929 /* For commutative operations, the RTX match if the operand match in any
4930 order. Also handle the simple binary and unary cases without a loop. */
4931 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4932 return ((rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4933 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
))
4934 || (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 1), yinsn
)
4935 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 0), yinsn
)));
4936 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4937 return (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
4938 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
));
4939 else if (GET_RTX_CLASS (code
) == '1')
4940 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4942 /* Handle special-cases first. */
4946 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
4949 /* If neither is user variable or hard register, check for possible
4951 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
4952 || REGNO (x
) < FIRST_PSEUDO_REGISTER
4953 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
4956 if (same_regs
[REGNO (x
)] == -1)
4958 same_regs
[REGNO (x
)] = REGNO (y
);
4961 /* If this is the first time we are seeing a register on the `Y'
4962 side, see if it is the last use. If not, we can't thread the
4963 jump, so mark it as not equivalent. */
4964 if (REGNO_LAST_UID (REGNO (y
)) != INSN_UID (yinsn
))
4970 return (same_regs
[REGNO (x
)] == REGNO (y
));
4975 /* If memory modified or either volatile, not equivalent.
4976 Else, check address. */
4977 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4980 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
4983 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
4989 /* Cancel a pending `same_regs' if setting equivalenced registers.
4990 Then process source. */
4991 if (GET_CODE (SET_DEST (x
)) == REG
4992 && GET_CODE (SET_DEST (y
)) == REG
)
4994 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
4996 same_regs
[REGNO (SET_DEST (x
))] = -1;
4999 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
5003 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
5006 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
5009 return XEXP (x
, 0) == XEXP (y
, 0);
5012 return XSTR (x
, 0) == XSTR (y
, 0);
5021 fmt
= GET_RTX_FORMAT (code
);
5022 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
5027 if (XWINT (x
, i
) != XWINT (y
, i
))
5033 if (XINT (x
, i
) != XINT (y
, i
))
5039 /* Two vectors must have the same length. */
5040 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
5043 /* And the corresponding elements must match. */
5044 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5045 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
5046 XVECEXP (y
, i
, j
), yinsn
) == 0)
5051 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
5057 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
5062 /* These are just backpointers, so they don't matter. */
5068 /* It is believed that rtx's at this level will never
5069 contain anything but integers and other rtx's,
5070 except for within LABEL_REFs and SYMBOL_REFs. */
5080 /* Return the insn that NEW can be safely inserted in front of starting at
5081 the jump insn INSN. Return 0 if it is not safe to do this jump
5082 optimization. Note that NEW must contain a single set. */
5085 find_insert_position (insn
, new)
5092 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
5093 if (GET_CODE (PATTERN (new)) != PARALLEL
)
5096 for (i
= XVECLEN (PATTERN (new), 0) - 1; i
>= 0; i
--)
5097 if (GET_CODE (XVECEXP (PATTERN (new), 0, i
)) == CLOBBER
5098 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
5105 /* There is a good chance that the previous insn PREV sets the thing
5106 being clobbered (often the CC in a hard reg). If PREV does not
5107 use what NEW sets, we can insert NEW before PREV. */
5109 prev
= prev_active_insn (insn
);
5110 for (i
= XVECLEN (PATTERN (new), 0) - 1; i
>= 0; i
--)
5111 if (GET_CODE (XVECEXP (PATTERN (new), 0, i
)) == CLOBBER
5112 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
5114 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
5118 return reg_mentioned_p (SET_DEST (single_set (new)), prev
) ? 0 : prev
;
5120 #endif /* !HAVE_cc0 */