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. */
59 #include "hard-reg-set.h"
61 #include "insn-config.h"
62 #include "insn-flags.h"
63 #include "insn-attr.h"
71 /* ??? Eventually must record somehow the labels used by jumps
72 from nested functions. */
73 /* Pre-record the next or previous real insn for each label?
74 No, this pass is very fast anyway. */
75 /* Condense consecutive labels?
76 This would make life analysis faster, maybe. */
77 /* Optimize jump y; x: ... y: jumpif... x?
78 Don't know if it is worth bothering with. */
79 /* Optimize two cases of conditional jump to conditional jump?
80 This can never delete any instruction or make anything dead,
81 or even change what is live at any point.
82 So perhaps let combiner do it. */
84 /* Vector indexed by uid.
85 For each CODE_LABEL, index by its uid to get first unconditional jump
86 that jumps to the label.
87 For each JUMP_INSN, index by its uid to get the next unconditional jump
88 that jumps to the same label.
89 Element 0 is the start of a chain of all return insns.
90 (It is safe to use element 0 because insn uid 0 is not used. */
92 static rtx
*jump_chain
;
94 /* Maximum index in jump_chain. */
96 static int max_jump_chain
;
98 /* Set nonzero by jump_optimize if control can fall through
99 to the end of the function. */
102 /* Indicates whether death notes are significant in cross jump analysis.
103 Normally they are not significant, because of A and B jump to C,
104 and R dies in A, it must die in B. But this might not be true after
105 stack register conversion, and we must compare death notes in that
108 static int cross_jump_death_matters
= 0;
110 static int init_label_info
PROTO((rtx
));
111 static void delete_barrier_successors
PROTO((rtx
));
112 static void mark_all_labels
PROTO((rtx
, int));
113 static rtx delete_unreferenced_labels
PROTO((rtx
));
114 static void delete_noop_moves
PROTO((rtx
));
115 static int calculate_can_reach_end
PROTO((rtx
, int, int));
116 static int duplicate_loop_exit_test
PROTO((rtx
));
117 static void find_cross_jump
PROTO((rtx
, rtx
, int, rtx
*, rtx
*));
118 static void do_cross_jump
PROTO((rtx
, rtx
, rtx
));
119 static int jump_back_p
PROTO((rtx
, rtx
));
120 static int tension_vector_labels
PROTO((rtx
, int));
121 static void mark_jump_label
PROTO((rtx
, rtx
, int));
122 static void delete_computation
PROTO((rtx
));
123 static void delete_from_jump_chain
PROTO((rtx
));
124 static int delete_labelref_insn
PROTO((rtx
, rtx
, int));
125 static void mark_modified_reg
PROTO((rtx
, rtx
));
126 static void redirect_tablejump
PROTO((rtx
, rtx
));
127 static void jump_optimize_1
PROTO ((rtx
, int, int, int, int));
128 #if ! defined(HAVE_cc0) && ! defined(HAVE_conditional_arithmetic)
129 static rtx find_insert_position
PROTO((rtx
, rtx
));
131 static int returnjump_p_1
PROTO((rtx
*, void *));
132 static void delete_prior_computation
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 /* Keep track of labels used from static data;
214 they cannot ever be deleted. */
216 for (insn
= forced_labels
; insn
; insn
= XEXP (insn
, 1))
217 LABEL_NUSES (XEXP (insn
, 0))++;
219 check_exception_handler_labels ();
221 /* Keep track of labels used for marking handlers for exception
222 regions; they cannot usually be deleted. */
224 for (insn
= exception_handler_labels
; insn
; insn
= XEXP (insn
, 1))
225 LABEL_NUSES (XEXP (insn
, 0))++;
227 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
228 notes and recompute LABEL_NUSES. */
229 if (mark_labels_only
)
232 exception_optimize ();
234 last_insn
= delete_unreferenced_labels (f
);
238 /* CAN_REACH_END is persistent for each function. Once set it should
239 not be cleared. This is especially true for the case where we
240 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
241 the front-end before compiling each function. */
242 if (calculate_can_reach_end (last_insn
, 1, 0))
245 /* Zero the "deleted" flag of all the "deleted" insns. */
246 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
247 INSN_DELETED_P (insn
) = 0;
249 /* Show that the jump chain is not valid. */
257 /* If we fall through to the epilogue, see if we can insert a RETURN insn
258 in front of it. If the machine allows it at this point (we might be
259 after reload for a leaf routine), it will improve optimization for it
261 insn
= get_last_insn ();
262 while (insn
&& GET_CODE (insn
) == NOTE
)
263 insn
= PREV_INSN (insn
);
265 if (insn
&& GET_CODE (insn
) != BARRIER
)
267 emit_jump_insn (gen_return ());
274 delete_noop_moves (f
);
276 /* If we haven't yet gotten to reload and we have just run regscan,
277 delete any insn that sets a register that isn't used elsewhere.
278 This helps some of the optimizations below by having less insns
279 being jumped around. */
281 if (! reload_completed
&& after_regscan
)
282 for (insn
= f
; insn
; insn
= next
)
284 rtx set
= single_set (insn
);
286 next
= NEXT_INSN (insn
);
288 if (set
&& GET_CODE (SET_DEST (set
)) == REG
289 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
290 && REGNO_FIRST_UID (REGNO (SET_DEST (set
))) == INSN_UID (insn
)
291 /* We use regno_last_note_uid so as not to delete the setting
292 of a reg that's used in notes. A subsequent optimization
293 might arrange to use that reg for real. */
294 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set
))) == INSN_UID (insn
)
295 && ! side_effects_p (SET_SRC (set
))
296 && ! find_reg_note (insn
, REG_RETVAL
, 0)
297 /* An ADDRESSOF expression can turn into a use of the internal arg
298 pointer, so do not delete the initialization of the internal
299 arg pointer yet. If it is truly dead, flow will delete the
300 initializing insn. */
301 && SET_DEST (set
) != current_function_internal_arg_pointer
)
305 /* Now iterate optimizing jumps until nothing changes over one pass. */
307 old_max_reg
= max_reg_num ();
312 for (insn
= f
; insn
; insn
= next
)
315 rtx temp
, temp1
, temp2
, temp3
, temp4
, temp5
, temp6
;
317 int this_is_simplejump
, this_is_condjump
, reversep
= 0;
318 int this_is_condjump_in_parallel
;
320 next
= NEXT_INSN (insn
);
322 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
323 jump. Try to optimize by duplicating the loop exit test if so.
324 This is only safe immediately after regscan, because it uses
325 the values of regno_first_uid and regno_last_uid. */
326 if (after_regscan
&& GET_CODE (insn
) == NOTE
327 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
328 && (temp1
= next_nonnote_insn (insn
)) != 0
329 && simplejump_p (temp1
))
331 temp
= PREV_INSN (insn
);
332 if (duplicate_loop_exit_test (insn
))
335 next
= NEXT_INSN (temp
);
340 if (GET_CODE (insn
) != JUMP_INSN
)
343 this_is_simplejump
= simplejump_p (insn
);
344 this_is_condjump
= condjump_p (insn
);
345 this_is_condjump_in_parallel
= condjump_in_parallel_p (insn
);
347 /* Tension the labels in dispatch tables. */
349 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
)
350 changed
|= tension_vector_labels (PATTERN (insn
), 0);
351 if (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
352 changed
|= tension_vector_labels (PATTERN (insn
), 1);
354 /* See if this jump goes to another jump and redirect if so. */
355 nlabel
= follow_jumps (JUMP_LABEL (insn
));
356 if (nlabel
!= JUMP_LABEL (insn
))
357 changed
|= redirect_jump (insn
, nlabel
);
359 /* If a dispatch table always goes to the same place,
360 get rid of it and replace the insn that uses it. */
362 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
363 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
366 rtx pat
= PATTERN (insn
);
367 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
368 int len
= XVECLEN (pat
, diff_vec_p
);
369 rtx dispatch
= prev_real_insn (insn
);
372 for (i
= 0; i
< len
; i
++)
373 if (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)
374 != XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0))
379 && GET_CODE (dispatch
) == JUMP_INSN
380 && JUMP_LABEL (dispatch
) != 0
381 /* Don't mess with a casesi insn.
382 XXX according to the comment before computed_jump_p(),
383 all casesi insns should be a parallel of the jump
384 and a USE of a LABEL_REF. */
385 && ! ((set
= single_set (dispatch
)) != NULL
386 && (GET_CODE (SET_SRC (set
)) == IF_THEN_ELSE
))
387 && next_real_insn (JUMP_LABEL (dispatch
)) == insn
)
389 redirect_tablejump (dispatch
,
390 XEXP (XVECEXP (pat
, diff_vec_p
, 0), 0));
395 /* If a jump references the end of the function, try to turn
396 it into a RETURN insn, possibly a conditional one. */
397 if (JUMP_LABEL (insn
) != 0
398 && (next_active_insn (JUMP_LABEL (insn
)) == 0
399 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn
))))
401 changed
|= redirect_jump (insn
, NULL_RTX
);
403 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
405 /* Detect jump to following insn. */
406 if (reallabelprev
== insn
&& this_is_condjump
)
408 next
= next_real_insn (JUMP_LABEL (insn
));
414 /* Detect a conditional jump going to the same place
415 as an immediately following unconditional jump. */
416 else if (this_is_condjump
417 && (temp
= next_active_insn (insn
)) != 0
418 && simplejump_p (temp
)
419 && (next_active_insn (JUMP_LABEL (insn
))
420 == next_active_insn (JUMP_LABEL (temp
))))
422 /* Don't mess up test coverage analysis. */
424 if (flag_test_coverage
&& !reload_completed
)
425 for (temp2
= insn
; temp2
!= temp
; temp2
= NEXT_INSN (temp2
))
426 if (GET_CODE (temp2
) == NOTE
&& NOTE_LINE_NUMBER (temp2
) > 0)
437 /* Detect a conditional jump jumping over an unconditional jump. */
439 else if ((this_is_condjump
|| this_is_condjump_in_parallel
)
440 && ! this_is_simplejump
441 && reallabelprev
!= 0
442 && GET_CODE (reallabelprev
) == JUMP_INSN
443 && prev_active_insn (reallabelprev
) == insn
444 && no_labels_between_p (insn
, reallabelprev
)
445 && simplejump_p (reallabelprev
))
447 /* When we invert the unconditional jump, we will be
448 decrementing the usage count of its old label.
449 Make sure that we don't delete it now because that
450 might cause the following code to be deleted. */
451 rtx prev_uses
= prev_nonnote_insn (reallabelprev
);
452 rtx prev_label
= JUMP_LABEL (insn
);
455 ++LABEL_NUSES (prev_label
);
457 if (invert_jump (insn
, JUMP_LABEL (reallabelprev
)))
459 /* It is very likely that if there are USE insns before
460 this jump, they hold REG_DEAD notes. These REG_DEAD
461 notes are no longer valid due to this optimization,
462 and will cause the life-analysis that following passes
463 (notably delayed-branch scheduling) to think that
464 these registers are dead when they are not.
466 To prevent this trouble, we just remove the USE insns
467 from the insn chain. */
469 while (prev_uses
&& GET_CODE (prev_uses
) == INSN
470 && GET_CODE (PATTERN (prev_uses
)) == USE
)
472 rtx useless
= prev_uses
;
473 prev_uses
= prev_nonnote_insn (prev_uses
);
474 delete_insn (useless
);
477 delete_insn (reallabelprev
);
481 /* We can now safely delete the label if it is unreferenced
482 since the delete_insn above has deleted the BARRIER. */
483 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
484 delete_insn (prev_label
);
486 next
= NEXT_INSN (insn
);
489 /* If we have an unconditional jump preceded by a USE, try to put
490 the USE before the target and jump there. This simplifies many
491 of the optimizations below since we don't have to worry about
492 dealing with these USE insns. We only do this if the label
493 being branch to already has the identical USE or if code
494 never falls through to that label. */
496 else if (this_is_simplejump
497 && (temp
= prev_nonnote_insn (insn
)) != 0
498 && GET_CODE (temp
) == INSN
499 && GET_CODE (PATTERN (temp
)) == USE
500 && (temp1
= prev_nonnote_insn (JUMP_LABEL (insn
))) != 0
501 && (GET_CODE (temp1
) == BARRIER
502 || (GET_CODE (temp1
) == INSN
503 && rtx_equal_p (PATTERN (temp
), PATTERN (temp1
))))
504 /* Don't do this optimization if we have a loop containing
505 only the USE instruction, and the loop start label has
506 a usage count of 1. This is because we will redo this
507 optimization everytime through the outer loop, and jump
508 opt will never exit. */
509 && ! ((temp2
= prev_nonnote_insn (temp
)) != 0
510 && temp2
== JUMP_LABEL (insn
)
511 && LABEL_NUSES (temp2
) == 1))
513 if (GET_CODE (temp1
) == BARRIER
)
515 emit_insn_after (PATTERN (temp
), temp1
);
516 temp1
= NEXT_INSN (temp1
);
520 redirect_jump (insn
, get_label_before (temp1
));
521 reallabelprev
= prev_real_insn (temp1
);
523 next
= NEXT_INSN (insn
);
526 /* Simplify if (...) x = a; else x = b; by converting it
527 to x = b; if (...) x = a;
528 if B is sufficiently simple, the test doesn't involve X,
529 and nothing in the test modifies B or X.
531 If we have small register classes, we also can't do this if X
534 If the "x = b;" insn has any REG_NOTES, we don't do this because
535 of the possibility that we are running after CSE and there is a
536 REG_EQUAL note that is only valid if the branch has already been
537 taken. If we move the insn with the REG_EQUAL note, we may
538 fold the comparison to always be false in a later CSE pass.
539 (We could also delete the REG_NOTES when moving the insn, but it
540 seems simpler to not move it.) An exception is that we can move
541 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
542 value is the same as "b".
544 INSN is the branch over the `else' part.
548 TEMP to the jump insn preceding "x = a;"
550 TEMP2 to the insn that sets "x = b;"
551 TEMP3 to the insn that sets "x = a;"
552 TEMP4 to the set of "x = b"; */
554 if (this_is_simplejump
555 && (temp3
= prev_active_insn (insn
)) != 0
556 && GET_CODE (temp3
) == INSN
557 && (temp4
= single_set (temp3
)) != 0
558 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
559 && (! SMALL_REGISTER_CLASSES
560 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
561 && (temp2
= next_active_insn (insn
)) != 0
562 && GET_CODE (temp2
) == INSN
563 && (temp4
= single_set (temp2
)) != 0
564 && rtx_equal_p (SET_DEST (temp4
), temp1
)
565 && ! side_effects_p (SET_SRC (temp4
))
566 && ! may_trap_p (SET_SRC (temp4
))
567 && (REG_NOTES (temp2
) == 0
568 || ((REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUAL
569 || REG_NOTE_KIND (REG_NOTES (temp2
)) == REG_EQUIV
)
570 && XEXP (REG_NOTES (temp2
), 1) == 0
571 && rtx_equal_p (XEXP (REG_NOTES (temp2
), 0),
573 && (temp
= prev_active_insn (temp3
)) != 0
574 && condjump_p (temp
) && ! simplejump_p (temp
)
575 /* TEMP must skip over the "x = a;" insn */
576 && prev_real_insn (JUMP_LABEL (temp
)) == insn
577 && no_labels_between_p (insn
, JUMP_LABEL (temp
))
578 /* There must be no other entries to the "x = b;" insn. */
579 && no_labels_between_p (JUMP_LABEL (temp
), temp2
)
580 /* INSN must either branch to the insn after TEMP2 or the insn
581 after TEMP2 must branch to the same place as INSN. */
582 && (reallabelprev
== temp2
583 || ((temp5
= next_active_insn (temp2
)) != 0
584 && simplejump_p (temp5
)
585 && JUMP_LABEL (temp5
) == JUMP_LABEL (insn
))))
587 /* The test expression, X, may be a complicated test with
588 multiple branches. See if we can find all the uses of
589 the label that TEMP branches to without hitting a CALL_INSN
590 or a jump to somewhere else. */
591 rtx target
= JUMP_LABEL (temp
);
592 int nuses
= LABEL_NUSES (target
);
598 /* Set P to the first jump insn that goes around "x = a;". */
599 for (p
= temp
; nuses
&& p
; p
= prev_nonnote_insn (p
))
601 if (GET_CODE (p
) == JUMP_INSN
)
603 if (condjump_p (p
) && ! simplejump_p (p
)
604 && JUMP_LABEL (p
) == target
)
613 else if (GET_CODE (p
) == CALL_INSN
)
618 /* We cannot insert anything between a set of cc and its use
619 so if P uses cc0, we must back up to the previous insn. */
620 q
= prev_nonnote_insn (p
);
621 if (q
&& GET_RTX_CLASS (GET_CODE (q
)) == 'i'
622 && sets_cc0_p (PATTERN (q
)))
629 /* If we found all the uses and there was no data conflict, we
630 can move the assignment unless we can branch into the middle
633 && no_labels_between_p (p
, insn
)
634 && ! reg_referenced_between_p (temp1
, p
, NEXT_INSN (temp3
))
635 && ! reg_set_between_p (temp1
, p
, temp3
)
636 && (GET_CODE (SET_SRC (temp4
)) == CONST_INT
637 || ! modified_between_p (SET_SRC (temp4
), p
, temp2
))
638 /* Verify that registers used by the jump are not clobbered
639 by the instruction being moved. */
640 && ! regs_set_between_p (PATTERN (temp
),
644 emit_insn_after_with_line_notes (PATTERN (temp2
), p
, temp2
);
647 /* Set NEXT to an insn that we know won't go away. */
648 next
= next_active_insn (insn
);
650 /* Delete the jump around the set. Note that we must do
651 this before we redirect the test jumps so that it won't
652 delete the code immediately following the assignment
653 we moved (which might be a jump). */
657 /* We either have two consecutive labels or a jump to
658 a jump, so adjust all the JUMP_INSNs to branch to where
660 for (p
= NEXT_INSN (p
); p
!= next
; p
= NEXT_INSN (p
))
661 if (GET_CODE (p
) == JUMP_INSN
)
662 redirect_jump (p
, target
);
665 next
= NEXT_INSN (insn
);
670 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
671 to x = a; if (...) goto l; x = b;
672 if A is sufficiently simple, the test doesn't involve X,
673 and nothing in the test modifies A or X.
675 If we have small register classes, we also can't do this if X
678 If the "x = a;" insn has any REG_NOTES, we don't do this because
679 of the possibility that we are running after CSE and there is a
680 REG_EQUAL note that is only valid if the branch has already been
681 taken. If we move the insn with the REG_EQUAL note, we may
682 fold the comparison to always be false in a later CSE pass.
683 (We could also delete the REG_NOTES when moving the insn, but it
684 seems simpler to not move it.) An exception is that we can move
685 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
686 value is the same as "a".
692 TEMP to the jump insn preceding "x = a;"
694 TEMP2 to the insn that sets "x = b;"
695 TEMP3 to the insn that sets "x = a;"
696 TEMP4 to the set of "x = a"; */
698 if (this_is_simplejump
699 && (temp2
= next_active_insn (insn
)) != 0
700 && GET_CODE (temp2
) == INSN
701 && (temp4
= single_set (temp2
)) != 0
702 && GET_CODE (temp1
= SET_DEST (temp4
)) == REG
703 && (! SMALL_REGISTER_CLASSES
704 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
705 && (temp3
= prev_active_insn (insn
)) != 0
706 && GET_CODE (temp3
) == INSN
707 && (temp4
= single_set (temp3
)) != 0
708 && rtx_equal_p (SET_DEST (temp4
), temp1
)
709 && ! side_effects_p (SET_SRC (temp4
))
710 && ! may_trap_p (SET_SRC (temp4
))
711 && (REG_NOTES (temp3
) == 0
712 || ((REG_NOTE_KIND (REG_NOTES (temp3
)) == REG_EQUAL
713 || REG_NOTE_KIND (REG_NOTES (temp3
)) == REG_EQUIV
)
714 && XEXP (REG_NOTES (temp3
), 1) == 0
715 && rtx_equal_p (XEXP (REG_NOTES (temp3
), 0),
717 && (temp
= prev_active_insn (temp3
)) != 0
718 && condjump_p (temp
) && ! simplejump_p (temp
)
719 /* TEMP must skip over the "x = a;" insn */
720 && prev_real_insn (JUMP_LABEL (temp
)) == insn
721 && no_labels_between_p (temp
, insn
))
723 rtx prev_label
= JUMP_LABEL (temp
);
724 rtx insert_after
= prev_nonnote_insn (temp
);
727 /* We cannot insert anything between a set of cc and its use. */
728 if (insert_after
&& GET_RTX_CLASS (GET_CODE (insert_after
)) == 'i'
729 && sets_cc0_p (PATTERN (insert_after
)))
730 insert_after
= prev_nonnote_insn (insert_after
);
732 ++LABEL_NUSES (prev_label
);
735 && no_labels_between_p (insert_after
, temp
)
736 && ! reg_referenced_between_p (temp1
, insert_after
, temp3
)
737 && ! reg_referenced_between_p (temp1
, temp3
,
739 && ! reg_set_between_p (temp1
, insert_after
, temp
)
740 && ! modified_between_p (SET_SRC (temp4
), insert_after
, temp
)
741 /* Verify that registers used by the jump are not clobbered
742 by the instruction being moved. */
743 && ! regs_set_between_p (PATTERN (temp
),
746 && invert_jump (temp
, JUMP_LABEL (insn
)))
748 emit_insn_after_with_line_notes (PATTERN (temp3
),
749 insert_after
, temp3
);
752 /* Set NEXT to an insn that we know won't go away. */
756 if (prev_label
&& --LABEL_NUSES (prev_label
) == 0)
757 delete_insn (prev_label
);
762 #if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
764 /* If we have if (...) x = exp; and branches are expensive,
765 EXP is a single insn, does not have any side effects, cannot
766 trap, and is not too costly, convert this to
767 t = exp; if (...) x = t;
769 Don't do this when we have CC0 because it is unlikely to help
770 and we'd need to worry about where to place the new insn and
771 the potential for conflicts. We also can't do this when we have
772 notes on the insn for the same reason as above.
774 If we have conditional arithmetic, this will make this
775 harder to optimize later and isn't needed, so don't do it
780 TEMP to the "x = exp;" insn.
781 TEMP1 to the single set in the "x = exp;" insn.
784 if (! reload_completed
785 && this_is_condjump
&& ! this_is_simplejump
787 && (temp
= next_nonnote_insn (insn
)) != 0
788 && GET_CODE (temp
) == INSN
789 && REG_NOTES (temp
) == 0
790 && (reallabelprev
== temp
791 || ((temp2
= next_active_insn (temp
)) != 0
792 && simplejump_p (temp2
)
793 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
794 && (temp1
= single_set (temp
)) != 0
795 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
796 && (! SMALL_REGISTER_CLASSES
797 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
798 && GET_CODE (SET_SRC (temp1
)) != REG
799 && GET_CODE (SET_SRC (temp1
)) != SUBREG
800 && GET_CODE (SET_SRC (temp1
)) != CONST_INT
801 && ! side_effects_p (SET_SRC (temp1
))
802 && ! may_trap_p (SET_SRC (temp1
))
803 && rtx_cost (SET_SRC (temp1
), SET
) < 10)
805 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
807 if ((temp3
= find_insert_position (insn
, temp
))
808 && validate_change (temp
, &SET_DEST (temp1
), new, 0))
810 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
811 emit_insn_after_with_line_notes (PATTERN (temp
),
812 PREV_INSN (temp3
), temp
);
814 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
818 reg_scan_update (temp3
, NEXT_INSN (next
), old_max_reg
);
819 old_max_reg
= max_reg_num ();
824 /* Similarly, if it takes two insns to compute EXP but they
825 have the same destination. Here TEMP3 will be the second
826 insn and TEMP4 the SET from that insn. */
828 if (! reload_completed
829 && this_is_condjump
&& ! this_is_simplejump
831 && (temp
= next_nonnote_insn (insn
)) != 0
832 && GET_CODE (temp
) == INSN
833 && REG_NOTES (temp
) == 0
834 && (temp3
= next_nonnote_insn (temp
)) != 0
835 && GET_CODE (temp3
) == INSN
836 && REG_NOTES (temp3
) == 0
837 && (reallabelprev
== temp3
838 || ((temp2
= next_active_insn (temp3
)) != 0
839 && simplejump_p (temp2
)
840 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
841 && (temp1
= single_set (temp
)) != 0
842 && (temp2
= SET_DEST (temp1
), GET_CODE (temp2
) == REG
)
843 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
844 && (! SMALL_REGISTER_CLASSES
845 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
846 && ! side_effects_p (SET_SRC (temp1
))
847 && ! may_trap_p (SET_SRC (temp1
))
848 && rtx_cost (SET_SRC (temp1
), SET
) < 10
849 && (temp4
= single_set (temp3
)) != 0
850 && rtx_equal_p (SET_DEST (temp4
), temp2
)
851 && ! side_effects_p (SET_SRC (temp4
))
852 && ! may_trap_p (SET_SRC (temp4
))
853 && rtx_cost (SET_SRC (temp4
), SET
) < 10)
855 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
857 if ((temp5
= find_insert_position (insn
, temp
))
858 && (temp6
= find_insert_position (insn
, temp3
))
859 && validate_change (temp
, &SET_DEST (temp1
), new, 0))
861 /* Use the earliest of temp5 and temp6. */
864 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
865 emit_insn_after_with_line_notes (PATTERN (temp
),
866 PREV_INSN (temp6
), temp
);
867 emit_insn_after_with_line_notes
868 (replace_rtx (PATTERN (temp3
), temp2
, new),
869 PREV_INSN (temp6
), temp3
);
872 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
876 reg_scan_update (temp6
, NEXT_INSN (next
), old_max_reg
);
877 old_max_reg
= max_reg_num ();
882 /* Finally, handle the case where two insns are used to
883 compute EXP but a temporary register is used. Here we must
884 ensure that the temporary register is not used anywhere else. */
886 if (! reload_completed
888 && this_is_condjump
&& ! this_is_simplejump
890 && (temp
= next_nonnote_insn (insn
)) != 0
891 && GET_CODE (temp
) == INSN
892 && REG_NOTES (temp
) == 0
893 && (temp3
= next_nonnote_insn (temp
)) != 0
894 && GET_CODE (temp3
) == INSN
895 && REG_NOTES (temp3
) == 0
896 && (reallabelprev
== temp3
897 || ((temp2
= next_active_insn (temp3
)) != 0
898 && simplejump_p (temp2
)
899 && JUMP_LABEL (temp2
) == JUMP_LABEL (insn
)))
900 && (temp1
= single_set (temp
)) != 0
901 && (temp5
= SET_DEST (temp1
),
902 (GET_CODE (temp5
) == REG
903 || (GET_CODE (temp5
) == SUBREG
904 && (temp5
= SUBREG_REG (temp5
),
905 GET_CODE (temp5
) == REG
))))
906 && REGNO (temp5
) >= FIRST_PSEUDO_REGISTER
907 && REGNO_FIRST_UID (REGNO (temp5
)) == INSN_UID (temp
)
908 && REGNO_LAST_UID (REGNO (temp5
)) == INSN_UID (temp3
)
909 && ! side_effects_p (SET_SRC (temp1
))
910 && ! may_trap_p (SET_SRC (temp1
))
911 && rtx_cost (SET_SRC (temp1
), SET
) < 10
912 && (temp4
= single_set (temp3
)) != 0
913 && (temp2
= SET_DEST (temp4
), GET_CODE (temp2
) == REG
)
914 && GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
915 && (! SMALL_REGISTER_CLASSES
916 || REGNO (temp2
) >= FIRST_PSEUDO_REGISTER
)
917 && rtx_equal_p (SET_DEST (temp4
), temp2
)
918 && ! side_effects_p (SET_SRC (temp4
))
919 && ! may_trap_p (SET_SRC (temp4
))
920 && rtx_cost (SET_SRC (temp4
), SET
) < 10)
922 rtx
new = gen_reg_rtx (GET_MODE (temp2
));
924 if ((temp5
= find_insert_position (insn
, temp
))
925 && (temp6
= find_insert_position (insn
, temp3
))
926 && validate_change (temp3
, &SET_DEST (temp4
), new, 0))
928 /* Use the earliest of temp5 and temp6. */
931 next
= emit_insn_after (gen_move_insn (temp2
, new), insn
);
932 emit_insn_after_with_line_notes (PATTERN (temp
),
933 PREV_INSN (temp6
), temp
);
934 emit_insn_after_with_line_notes (PATTERN (temp3
),
935 PREV_INSN (temp6
), temp3
);
938 reallabelprev
= prev_active_insn (JUMP_LABEL (insn
));
942 reg_scan_update (temp6
, NEXT_INSN (next
), old_max_reg
);
943 old_max_reg
= max_reg_num ();
947 #endif /* HAVE_cc0 */
949 #ifdef HAVE_conditional_arithmetic
950 /* ??? This is disabled in genconfig, as this simple-minded
951 transformation can incredibly lengthen register lifetimes.
953 Consider this example from cexp.c's yyparse:
956 (if_then_else (ne (reg:DI 149) (const_int 0 [0x0]))
957 (label_ref 248) (pc)))
958 237 (set (reg/i:DI 0 $0) (const_int 1 [0x1]))
959 239 (set (pc) (label_ref 2382))
960 248 (code_label ("yybackup"))
962 This will be transformed to:
964 237 (set (reg/i:DI 0 $0)
965 (if_then_else:DI (eq (reg:DI 149) (const_int 0 [0x0]))
966 (const_int 1 [0x1]) (reg/i:DI 0 $0)))
968 (if_then_else (eq (reg:DI 149) (const_int 0 [0x0]))
969 (label_ref 2382) (pc)))
971 which, from this narrow viewpoint looks fine. Except that
972 between this and 3 other ocurrences of the same pattern, $0
973 is now live for basically the entire function, and we'll
974 get an abort in caller_save.
976 Any replacement for this code should recall that a set of
977 a register that is not live need not, and indeed should not,
978 be conditionalized. Either that, or delay the transformation
979 until after register allocation. */
981 /* See if this is a conditional jump around a small number of
982 instructions that we can conditionalize. Don't do this before
983 the initial CSE pass or after reload.
985 We reject any insns that have side effects or may trap.
986 Strictly speaking, this is not needed since the machine may
987 support conditionalizing these too, but we won't deal with that
988 now. Specifically, this means that we can't conditionalize a
989 CALL_INSN, which some machines, such as the ARC, can do, but
990 this is a very minor optimization. */
991 if (this_is_condjump
&& ! this_is_simplejump
992 && cse_not_expected
&& optimize
> 0 && ! reload_completed
994 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (insn
)), 0),
997 rtx ourcond
= XEXP (SET_SRC (PATTERN (insn
)), 0);
999 char *storage
= (char *) oballoc (0);
1000 int last_insn
= 0, failed
= 0;
1001 rtx changed_jump
= 0;
1003 ourcond
= gen_rtx (reverse_condition (GET_CODE (ourcond
)),
1004 VOIDmode
, XEXP (ourcond
, 0),
1007 /* Scan forward BRANCH_COST real insns looking for the JUMP_LABEL
1008 of this insn. We see if we think we can conditionalize the
1009 insns we pass. For now, we only deal with insns that have
1010 one SET. We stop after an insn that modifies anything in
1011 OURCOND, if we have too many insns, or if we have an insn
1012 with a side effect or that may trip. Note that we will
1013 be modifying any unconditional jumps we encounter to be
1014 conditional; this will have the effect of also doing this
1015 optimization on the "else" the next time around. */
1016 for (temp1
= NEXT_INSN (insn
);
1017 num_insns
<= BRANCH_COST
&& ! failed
&& temp1
!= 0
1018 && GET_CODE (temp1
) != CODE_LABEL
;
1019 temp1
= NEXT_INSN (temp1
))
1021 /* Ignore everything but an active insn. */
1022 if (GET_RTX_CLASS (GET_CODE (temp1
)) != 'i'
1023 || GET_CODE (PATTERN (temp1
)) == USE
1024 || GET_CODE (PATTERN (temp1
)) == CLOBBER
)
1027 /* If this was an unconditional jump, record it since we'll
1028 need to remove the BARRIER if we succeed. We can only
1029 have one such jump since there must be a label after
1030 the BARRIER and it's either ours, in which case it's the
1031 only one or some other, in which case we'd fail. */
1033 if (simplejump_p (temp1
))
1034 changed_jump
= temp1
;
1036 /* See if we are allowed another insn and if this insn
1037 if one we think we may be able to handle. */
1038 if (++num_insns
> BRANCH_COST
1040 || (temp2
= single_set (temp1
)) == 0
1041 || side_effects_p (SET_SRC (temp2
))
1042 || may_trap_p (SET_SRC (temp2
)))
1045 validate_change (temp1
, &SET_SRC (temp2
),
1046 gen_rtx_IF_THEN_ELSE
1047 (GET_MODE (SET_DEST (temp2
)),
1049 SET_SRC (temp2
), SET_DEST (temp2
)),
1052 if (modified_in_p (ourcond
, temp1
))
1056 /* If we've reached our jump label, haven't failed, and all
1057 the changes above are valid, we can delete this jump
1058 insn. Also remove a BARRIER after any jump that used
1059 to be unconditional and remove any REG_EQUAL or REG_EQUIV
1060 that might have previously been present on insns we
1061 made conditional. */
1062 if (temp1
== JUMP_LABEL (insn
) && ! failed
1063 && apply_change_group ())
1065 for (temp1
= NEXT_INSN (insn
); temp1
!= JUMP_LABEL (insn
);
1066 temp1
= NEXT_INSN (temp1
))
1067 if (GET_RTX_CLASS (GET_CODE (temp1
)) == 'i')
1068 for (temp2
= REG_NOTES (temp1
); temp2
!= 0;
1069 temp2
= XEXP (temp2
, 1))
1070 if (REG_NOTE_KIND (temp2
) == REG_EQUAL
1071 || REG_NOTE_KIND (temp2
) == REG_EQUIV
)
1072 remove_note (temp1
, temp2
);
1074 if (changed_jump
!= 0)
1076 if (GET_CODE (NEXT_INSN (changed_jump
)) != BARRIER
)
1079 delete_insn (NEXT_INSN (changed_jump
));
1094 /* Try to use a conditional move (if the target has them), or a
1095 store-flag insn. If the target has conditional arithmetic as
1096 well as conditional move, the above code will have done something.
1097 Note that we prefer the above code since it is more general: the
1098 code below can make changes that require work to undo.
1100 The general case here is:
1102 1) x = a; if (...) x = b; and
1105 If the jump would be faster, the machine should not have defined
1106 the movcc or scc insns!. These cases are often made by the
1107 previous optimization.
1109 The second case is treated as x = x; if (...) x = b;.
1111 INSN here is the jump around the store. We set:
1113 TEMP to the "x op= b;" insn.
1116 TEMP3 to A (X in the second case).
1117 TEMP4 to the condition being tested.
1118 TEMP5 to the earliest insn used to find the condition.
1119 TEMP6 to the SET of TEMP. */
1121 if (/* We can't do this after reload has completed. */
1123 #ifdef HAVE_conditional_arithmetic
1124 /* Defer this until after CSE so the above code gets the
1125 first crack at it. */
1128 && this_is_condjump
&& ! this_is_simplejump
1129 /* Set TEMP to the "x = b;" insn. */
1130 && (temp
= next_nonnote_insn (insn
)) != 0
1131 && GET_CODE (temp
) == INSN
1132 && (temp6
= single_set (temp
)) != NULL_RTX
1133 && GET_CODE (temp1
= SET_DEST (temp6
)) == REG
1134 && (! SMALL_REGISTER_CLASSES
1135 || REGNO (temp1
) >= FIRST_PSEUDO_REGISTER
)
1136 && ! side_effects_p (temp2
= SET_SRC (temp6
))
1137 && ! may_trap_p (temp2
)
1138 /* Allow either form, but prefer the former if both apply.
1139 There is no point in using the old value of TEMP1 if
1140 it is a register, since cse will alias them. It can
1141 lose if the old value were a hard register since CSE
1142 won't replace hard registers. Avoid using TEMP3 if
1143 small register classes and it is a hard register. */
1144 && (((temp3
= reg_set_last (temp1
, insn
)) != 0
1145 && ! (SMALL_REGISTER_CLASSES
&& GET_CODE (temp3
) == REG
1146 && REGNO (temp3
) < FIRST_PSEUDO_REGISTER
))
1147 /* Make the latter case look like x = x; if (...) x = b; */
1148 || (temp3
= temp1
, 1))
1149 /* INSN must either branch to the insn after TEMP or the insn
1150 after TEMP must branch to the same place as INSN. */
1151 && (reallabelprev
== temp
1152 || ((temp4
= next_active_insn (temp
)) != 0
1153 && simplejump_p (temp4
)
1154 && JUMP_LABEL (temp4
) == JUMP_LABEL (insn
)))
1155 && (temp4
= get_condition (insn
, &temp5
)) != 0
1156 /* We must be comparing objects whose modes imply the size.
1157 We could handle BLKmode if (1) emit_store_flag could
1158 and (2) we could find the size reliably. */
1159 && GET_MODE (XEXP (temp4
, 0)) != BLKmode
1160 /* Even if branches are cheap, the store_flag optimization
1161 can win when the operation to be performed can be
1162 expressed directly. */
1164 /* If the previous insn sets CC0 and something else, we can't
1165 do this since we are going to delete that insn. */
1167 && ! ((temp6
= prev_nonnote_insn (insn
)) != 0
1168 && GET_CODE (temp6
) == INSN
1169 && (sets_cc0_p (PATTERN (temp6
)) == -1
1170 || (sets_cc0_p (PATTERN (temp6
)) == 1
1171 && FIND_REG_INC_NOTE (temp6
, NULL_RTX
))))
1175 #ifdef HAVE_conditional_move
1176 /* First try a conditional move. */
1178 enum rtx_code code
= GET_CODE (temp4
);
1180 rtx cond0
, cond1
, aval
, bval
;
1181 rtx target
, new_insn
;
1183 /* Copy the compared variables into cond0 and cond1, so that
1184 any side effects performed in or after the old comparison,
1185 will not affect our compare which will come later. */
1186 /* ??? Is it possible to just use the comparison in the jump
1187 insn? After all, we're going to delete it. We'd have
1188 to modify emit_conditional_move to take a comparison rtx
1189 instead or write a new function. */
1190 cond0
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 0)));
1191 /* We want the target to be able to simplify comparisons with
1192 zero (and maybe other constants as well), so don't create
1193 pseudos for them. There's no need to either. */
1194 if (GET_CODE (XEXP (temp4
, 1)) == CONST_INT
1195 || GET_CODE (XEXP (temp4
, 1)) == CONST_DOUBLE
)
1196 cond1
= XEXP (temp4
, 1);
1198 cond1
= gen_reg_rtx (GET_MODE (XEXP (temp4
, 1)));
1200 /* Careful about copying these values -- an IOR or what may
1201 need to do other things, like clobber flags. */
1202 /* ??? Assume for the moment that AVAL is ok. */
1207 /* We're dealing with a single_set insn with no side effects
1208 on SET_SRC. We do need to be reasonably certain that if
1209 we need to force BVAL into a register that we won't
1210 clobber the flags -- general_operand should suffice. */
1211 if (general_operand (temp2
, GET_MODE (var
)))
1215 bval
= gen_reg_rtx (GET_MODE (var
));
1216 new_insn
= copy_rtx (temp
);
1217 temp6
= single_set (new_insn
);
1218 SET_DEST (temp6
) = bval
;
1219 emit_insn (PATTERN (new_insn
));
1222 target
= emit_conditional_move (var
, code
,
1223 cond0
, cond1
, VOIDmode
,
1224 aval
, bval
, GET_MODE (var
),
1225 (code
== LTU
|| code
== GEU
1226 || code
== LEU
|| code
== GTU
));
1230 rtx seq1
, seq2
, last
;
1233 /* Save the conditional move sequence but don't emit it
1234 yet. On some machines, like the alpha, it is possible
1235 that temp5 == insn, so next generate the sequence that
1236 saves the compared values and then emit both
1237 sequences ensuring seq1 occurs before seq2. */
1238 seq2
= get_insns ();
1241 /* "Now that we can't fail..." Famous last words.
1242 Generate the copy insns that preserve the compared
1245 emit_move_insn (cond0
, XEXP (temp4
, 0));
1246 if (cond1
!= XEXP (temp4
, 1))
1247 emit_move_insn (cond1
, XEXP (temp4
, 1));
1248 seq1
= get_insns ();
1251 /* Validate the sequence -- this may be some weird
1252 bit-extract-and-test instruction for which there
1253 exists no complimentary bit-extract insn. */
1255 for (last
= seq1
; last
; last
= NEXT_INSN (last
))
1256 if (recog_memoized (last
) < 0)
1264 emit_insns_before (seq1
, temp5
);
1266 /* Insert conditional move after insn, to be sure
1267 that the jump and a possible compare won't be
1269 last
= emit_insns_after (seq2
, insn
);
1271 /* ??? We can also delete the insn that sets X to A.
1272 Flow will do it too though. */
1274 next
= NEXT_INSN (insn
);
1279 reg_scan_update (seq1
, NEXT_INSN (last
),
1281 old_max_reg
= max_reg_num ();
1293 /* That didn't work, try a store-flag insn.
1295 We further divide the cases into:
1297 1) x = a; if (...) x = b; and either A or B is zero,
1298 2) if (...) x = 0; and jumps are expensive,
1299 3) x = a; if (...) x = b; and A and B are constants where all
1300 the set bits in A are also set in B and jumps are expensive,
1301 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1303 5) if (...) x = b; if jumps are even more expensive. */
1305 if (GET_MODE_CLASS (GET_MODE (temp1
)) == MODE_INT
1306 && ((GET_CODE (temp3
) == CONST_INT
)
1307 /* Make the latter case look like
1308 x = x; if (...) x = 0; */
1311 && temp2
== const0_rtx
)
1312 || BRANCH_COST
>= 3)))
1313 /* If B is zero, OK; if A is zero, can only do (1) if we
1314 can reverse the condition. See if (3) applies possibly
1315 by reversing the condition. Prefer reversing to (4) when
1316 branches are very expensive. */
1317 && (((BRANCH_COST
>= 2
1318 || STORE_FLAG_VALUE
== -1
1319 || (STORE_FLAG_VALUE
== 1
1320 /* Check that the mask is a power of two,
1321 so that it can probably be generated
1323 && GET_CODE (temp3
) == CONST_INT
1324 && exact_log2 (INTVAL (temp3
)) >= 0))
1325 && (reversep
= 0, temp2
== const0_rtx
))
1326 || ((BRANCH_COST
>= 2
1327 || STORE_FLAG_VALUE
== -1
1328 || (STORE_FLAG_VALUE
== 1
1329 && GET_CODE (temp2
) == CONST_INT
1330 && exact_log2 (INTVAL (temp2
)) >= 0))
1331 && temp3
== const0_rtx
1332 && (reversep
= can_reverse_comparison_p (temp4
, insn
)))
1333 || (BRANCH_COST
>= 2
1334 && GET_CODE (temp2
) == CONST_INT
1335 && GET_CODE (temp3
) == CONST_INT
1336 && ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp2
)
1337 || ((INTVAL (temp2
) & INTVAL (temp3
)) == INTVAL (temp3
)
1338 && (reversep
= can_reverse_comparison_p (temp4
,
1340 || BRANCH_COST
>= 3)
1343 enum rtx_code code
= GET_CODE (temp4
);
1344 rtx uval
, cval
, var
= temp1
;
1348 /* If necessary, reverse the condition. */
1350 code
= reverse_condition (code
), uval
= temp2
, cval
= temp3
;
1352 uval
= temp3
, cval
= temp2
;
1354 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1355 is the constant 1, it is best to just compute the result
1356 directly. If UVAL is constant and STORE_FLAG_VALUE
1357 includes all of its bits, it is best to compute the flag
1358 value unnormalized and `and' it with UVAL. Otherwise,
1359 normalize to -1 and `and' with UVAL. */
1360 normalizep
= (cval
!= const0_rtx
? -1
1361 : (uval
== const1_rtx
? 1
1362 : (GET_CODE (uval
) == CONST_INT
1363 && (INTVAL (uval
) & ~STORE_FLAG_VALUE
) == 0)
1366 /* We will be putting the store-flag insn immediately in
1367 front of the comparison that was originally being done,
1368 so we know all the variables in TEMP4 will be valid.
1369 However, this might be in front of the assignment of
1370 A to VAR. If it is, it would clobber the store-flag
1371 we will be emitting.
1373 Therefore, emit into a temporary which will be copied to
1374 VAR immediately after TEMP. */
1377 target
= emit_store_flag (gen_reg_rtx (GET_MODE (var
)), code
,
1378 XEXP (temp4
, 0), XEXP (temp4
, 1),
1380 (code
== LTU
|| code
== LEU
1381 || code
== GEU
|| code
== GTU
),
1391 /* Put the store-flag insns in front of the first insn
1392 used to compute the condition to ensure that we
1393 use the same values of them as the current
1394 comparison. However, the remainder of the insns we
1395 generate will be placed directly in front of the
1396 jump insn, in case any of the pseudos we use
1397 are modified earlier. */
1399 emit_insns_before (seq
, temp5
);
1403 /* Both CVAL and UVAL are non-zero. */
1404 if (cval
!= const0_rtx
&& uval
!= const0_rtx
)
1408 tem1
= expand_and (uval
, target
, NULL_RTX
);
1409 if (GET_CODE (cval
) == CONST_INT
1410 && GET_CODE (uval
) == CONST_INT
1411 && (INTVAL (cval
) & INTVAL (uval
)) == INTVAL (cval
))
1415 tem2
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1416 target
, NULL_RTX
, 0);
1417 tem2
= expand_and (cval
, tem2
,
1418 (GET_CODE (tem2
) == REG
1422 /* If we usually make new pseudos, do so here. This
1423 turns out to help machines that have conditional
1425 /* ??? Conditional moves have already been handled.
1426 This may be obsolete. */
1428 if (flag_expensive_optimizations
)
1431 target
= expand_binop (GET_MODE (var
), ior_optab
,
1435 else if (normalizep
!= 1)
1437 /* We know that either CVAL or UVAL is zero. If
1438 UVAL is zero, negate TARGET and `and' with CVAL.
1439 Otherwise, `and' with UVAL. */
1440 if (uval
== const0_rtx
)
1442 target
= expand_unop (GET_MODE (var
), one_cmpl_optab
,
1443 target
, NULL_RTX
, 0);
1447 target
= expand_and (uval
, target
,
1448 (GET_CODE (target
) == REG
1449 && ! preserve_subexpressions_p ()
1450 ? target
: NULL_RTX
));
1453 emit_move_insn (var
, target
);
1457 /* If INSN uses CC0, we must not separate it from the
1458 insn that sets cc0. */
1459 if (reg_mentioned_p (cc0_rtx
, PATTERN (before
)))
1460 before
= prev_nonnote_insn (before
);
1462 emit_insns_before (seq
, before
);
1465 next
= NEXT_INSN (insn
);
1470 reg_scan_update (seq
, NEXT_INSN (next
), old_max_reg
);
1471 old_max_reg
= max_reg_num ();
1482 /* If branches are expensive, convert
1483 if (foo) bar++; to bar += (foo != 0);
1484 and similarly for "bar--;"
1486 INSN is the conditional branch around the arithmetic. We set:
1488 TEMP is the arithmetic insn.
1489 TEMP1 is the SET doing the arithmetic.
1490 TEMP2 is the operand being incremented or decremented.
1491 TEMP3 to the condition being tested.
1492 TEMP4 to the earliest insn used to find the condition. */
1494 if ((BRANCH_COST
>= 2
1502 && ! reload_completed
1503 && this_is_condjump
&& ! this_is_simplejump
1504 && (temp
= next_nonnote_insn (insn
)) != 0
1505 && (temp1
= single_set (temp
)) != 0
1506 && (temp2
= SET_DEST (temp1
),
1507 GET_MODE_CLASS (GET_MODE (temp2
)) == MODE_INT
)
1508 && GET_CODE (SET_SRC (temp1
)) == PLUS
1509 && (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1510 || XEXP (SET_SRC (temp1
), 1) == constm1_rtx
)
1511 && rtx_equal_p (temp2
, XEXP (SET_SRC (temp1
), 0))
1512 && ! side_effects_p (temp2
)
1513 && ! may_trap_p (temp2
)
1514 /* INSN must either branch to the insn after TEMP or the insn
1515 after TEMP must branch to the same place as INSN. */
1516 && (reallabelprev
== temp
1517 || ((temp3
= next_active_insn (temp
)) != 0
1518 && simplejump_p (temp3
)
1519 && JUMP_LABEL (temp3
) == JUMP_LABEL (insn
)))
1520 && (temp3
= get_condition (insn
, &temp4
)) != 0
1521 /* We must be comparing objects whose modes imply the size.
1522 We could handle BLKmode if (1) emit_store_flag could
1523 and (2) we could find the size reliably. */
1524 && GET_MODE (XEXP (temp3
, 0)) != BLKmode
1525 && can_reverse_comparison_p (temp3
, insn
))
1527 rtx temp6
, target
= 0, seq
, init_insn
= 0, init
= temp2
;
1528 enum rtx_code code
= reverse_condition (GET_CODE (temp3
));
1532 /* It must be the case that TEMP2 is not modified in the range
1533 [TEMP4, INSN). The one exception we make is if the insn
1534 before INSN sets TEMP2 to something which is also unchanged
1535 in that range. In that case, we can move the initialization
1536 into our sequence. */
1538 if ((temp5
= prev_active_insn (insn
)) != 0
1539 && no_labels_between_p (temp5
, insn
)
1540 && GET_CODE (temp5
) == INSN
1541 && (temp6
= single_set (temp5
)) != 0
1542 && rtx_equal_p (temp2
, SET_DEST (temp6
))
1543 && (CONSTANT_P (SET_SRC (temp6
))
1544 || GET_CODE (SET_SRC (temp6
)) == REG
1545 || GET_CODE (SET_SRC (temp6
)) == SUBREG
))
1547 emit_insn (PATTERN (temp5
));
1549 init
= SET_SRC (temp6
);
1552 if (CONSTANT_P (init
)
1553 || ! reg_set_between_p (init
, PREV_INSN (temp4
), insn
))
1554 target
= emit_store_flag (gen_reg_rtx (GET_MODE (temp2
)), code
,
1555 XEXP (temp3
, 0), XEXP (temp3
, 1),
1557 (code
== LTU
|| code
== LEU
1558 || code
== GTU
|| code
== GEU
), 1);
1560 /* If we can do the store-flag, do the addition or
1564 target
= expand_binop (GET_MODE (temp2
),
1565 (XEXP (SET_SRC (temp1
), 1) == const1_rtx
1566 ? add_optab
: sub_optab
),
1567 temp2
, target
, temp2
, 0, OPTAB_WIDEN
);
1571 /* Put the result back in temp2 in case it isn't already.
1572 Then replace the jump, possible a CC0-setting insn in
1573 front of the jump, and TEMP, with the sequence we have
1576 if (target
!= temp2
)
1577 emit_move_insn (temp2
, target
);
1582 emit_insns_before (seq
, temp4
);
1586 delete_insn (init_insn
);
1588 next
= NEXT_INSN (insn
);
1590 delete_insn (prev_nonnote_insn (insn
));
1596 reg_scan_update (seq
, NEXT_INSN (next
), old_max_reg
);
1597 old_max_reg
= max_reg_num ();
1607 /* Simplify if (...) x = 1; else {...} if (x) ...
1608 We recognize this case scanning backwards as well.
1610 TEMP is the assignment to x;
1611 TEMP1 is the label at the head of the second if. */
1612 /* ?? This should call get_condition to find the values being
1613 compared, instead of looking for a COMPARE insn when HAVE_cc0
1614 is not defined. This would allow it to work on the m88k. */
1615 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1616 is not defined and the condition is tested by a separate compare
1617 insn. This is because the code below assumes that the result
1618 of the compare dies in the following branch.
1620 Not only that, but there might be other insns between the
1621 compare and branch whose results are live. Those insns need
1624 A way to fix this is to move the insns at JUMP_LABEL (insn)
1625 to before INSN. If we are running before flow, they will
1626 be deleted if they aren't needed. But this doesn't work
1629 This is really a special-case of jump threading, anyway. The
1630 right thing to do is to replace this and jump threading with
1631 much simpler code in cse.
1633 This code has been turned off in the non-cc0 case in the
1637 else if (this_is_simplejump
1638 /* Safe to skip USE and CLOBBER insns here
1639 since they will not be deleted. */
1640 && (temp
= prev_active_insn (insn
))
1641 && no_labels_between_p (temp
, insn
)
1642 && GET_CODE (temp
) == INSN
1643 && GET_CODE (PATTERN (temp
)) == SET
1644 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1645 && CONSTANT_P (SET_SRC (PATTERN (temp
)))
1646 && (temp1
= next_active_insn (JUMP_LABEL (insn
)))
1647 /* If we find that the next value tested is `x'
1648 (TEMP1 is the insn where this happens), win. */
1649 && GET_CODE (temp1
) == INSN
1650 && GET_CODE (PATTERN (temp1
)) == SET
1652 /* Does temp1 `tst' the value of x? */
1653 && SET_SRC (PATTERN (temp1
)) == SET_DEST (PATTERN (temp
))
1654 && SET_DEST (PATTERN (temp1
)) == cc0_rtx
1655 && (temp1
= next_nonnote_insn (temp1
))
1657 /* Does temp1 compare the value of x against zero? */
1658 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1659 && XEXP (SET_SRC (PATTERN (temp1
)), 1) == const0_rtx
1660 && (XEXP (SET_SRC (PATTERN (temp1
)), 0)
1661 == SET_DEST (PATTERN (temp
)))
1662 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1663 && (temp1
= find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1665 && condjump_p (temp1
))
1667 /* Get the if_then_else from the condjump. */
1668 rtx choice
= SET_SRC (PATTERN (temp1
));
1669 if (GET_CODE (choice
) == IF_THEN_ELSE
)
1671 enum rtx_code code
= GET_CODE (XEXP (choice
, 0));
1672 rtx val
= SET_SRC (PATTERN (temp
));
1674 = simplify_relational_operation (code
, GET_MODE (SET_DEST (PATTERN (temp
))),
1678 if (cond
== const_true_rtx
)
1679 ultimate
= XEXP (choice
, 1);
1680 else if (cond
== const0_rtx
)
1681 ultimate
= XEXP (choice
, 2);
1685 if (ultimate
== pc_rtx
)
1686 ultimate
= get_label_after (temp1
);
1687 else if (ultimate
&& GET_CODE (ultimate
) != RETURN
)
1688 ultimate
= XEXP (ultimate
, 0);
1690 if (ultimate
&& JUMP_LABEL(insn
) != ultimate
)
1691 changed
|= redirect_jump (insn
, ultimate
);
1697 /* @@ This needs a bit of work before it will be right.
1699 Any type of comparison can be accepted for the first and
1700 second compare. When rewriting the first jump, we must
1701 compute the what conditions can reach label3, and use the
1702 appropriate code. We can not simply reverse/swap the code
1703 of the first jump. In some cases, the second jump must be
1707 < == converts to > ==
1708 < != converts to == >
1711 If the code is written to only accept an '==' test for the second
1712 compare, then all that needs to be done is to swap the condition
1713 of the first branch.
1715 It is questionable whether we want this optimization anyways,
1716 since if the user wrote code like this because he/she knew that
1717 the jump to label1 is taken most of the time, then rewriting
1718 this gives slower code. */
1719 /* @@ This should call get_condition to find the values being
1720 compared, instead of looking for a COMPARE insn when HAVE_cc0
1721 is not defined. This would allow it to work on the m88k. */
1722 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1723 is not defined and the condition is tested by a separate compare
1724 insn. This is because the code below assumes that the result
1725 of the compare dies in the following branch. */
1727 /* Simplify test a ~= b
1741 where ~= is an inequality, e.g. >, and ~~= is the swapped
1744 We recognize this case scanning backwards.
1746 TEMP is the conditional jump to `label2';
1747 TEMP1 is the test for `a == b';
1748 TEMP2 is the conditional jump to `label1';
1749 TEMP3 is the test for `a ~= b'. */
1750 else if (this_is_simplejump
1751 && (temp
= prev_active_insn (insn
))
1752 && no_labels_between_p (temp
, insn
)
1753 && condjump_p (temp
)
1754 && (temp1
= prev_active_insn (temp
))
1755 && no_labels_between_p (temp1
, temp
)
1756 && GET_CODE (temp1
) == INSN
1757 && GET_CODE (PATTERN (temp1
)) == SET
1759 && sets_cc0_p (PATTERN (temp1
)) == 1
1761 && GET_CODE (SET_SRC (PATTERN (temp1
))) == COMPARE
1762 && GET_CODE (SET_DEST (PATTERN (temp1
))) == REG
1763 && (temp
== find_next_ref (SET_DEST (PATTERN (temp1
)), temp1
))
1765 && (temp2
= prev_active_insn (temp1
))
1766 && no_labels_between_p (temp2
, temp1
)
1767 && condjump_p (temp2
)
1768 && JUMP_LABEL (temp2
) == next_nonnote_insn (NEXT_INSN (insn
))
1769 && (temp3
= prev_active_insn (temp2
))
1770 && no_labels_between_p (temp3
, temp2
)
1771 && GET_CODE (PATTERN (temp3
)) == SET
1772 && rtx_equal_p (SET_DEST (PATTERN (temp3
)),
1773 SET_DEST (PATTERN (temp1
)))
1774 && rtx_equal_p (SET_SRC (PATTERN (temp1
)),
1775 SET_SRC (PATTERN (temp3
)))
1776 && ! inequality_comparisons_p (PATTERN (temp
))
1777 && inequality_comparisons_p (PATTERN (temp2
)))
1779 rtx fallthrough_label
= JUMP_LABEL (temp2
);
1781 ++LABEL_NUSES (fallthrough_label
);
1782 if (swap_jump (temp2
, JUMP_LABEL (insn
)))
1788 if (--LABEL_NUSES (fallthrough_label
) == 0)
1789 delete_insn (fallthrough_label
);
1792 /* Simplify if (...) {... x = 1;} if (x) ...
1794 We recognize this case backwards.
1796 TEMP is the test of `x';
1797 TEMP1 is the assignment to `x' at the end of the
1798 previous statement. */
1799 /* @@ This should call get_condition to find the values being
1800 compared, instead of looking for a COMPARE insn when HAVE_cc0
1801 is not defined. This would allow it to work on the m88k. */
1802 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1803 is not defined and the condition is tested by a separate compare
1804 insn. This is because the code below assumes that the result
1805 of the compare dies in the following branch. */
1807 /* ??? This has to be turned off. The problem is that the
1808 unconditional jump might indirectly end up branching to the
1809 label between TEMP1 and TEMP. We can't detect this, in general,
1810 since it may become a jump to there after further optimizations.
1811 If that jump is done, it will be deleted, so we will retry
1812 this optimization in the next pass, thus an infinite loop.
1814 The present code prevents this by putting the jump after the
1815 label, but this is not logically correct. */
1817 else if (this_is_condjump
1818 /* Safe to skip USE and CLOBBER insns here
1819 since they will not be deleted. */
1820 && (temp
= prev_active_insn (insn
))
1821 && no_labels_between_p (temp
, insn
)
1822 && GET_CODE (temp
) == INSN
1823 && GET_CODE (PATTERN (temp
)) == SET
1825 && sets_cc0_p (PATTERN (temp
)) == 1
1826 && GET_CODE (SET_SRC (PATTERN (temp
))) == REG
1828 /* Temp must be a compare insn, we can not accept a register
1829 to register move here, since it may not be simply a
1831 && GET_CODE (SET_SRC (PATTERN (temp
))) == COMPARE
1832 && XEXP (SET_SRC (PATTERN (temp
)), 1) == const0_rtx
1833 && GET_CODE (XEXP (SET_SRC (PATTERN (temp
)), 0)) == REG
1834 && GET_CODE (SET_DEST (PATTERN (temp
))) == REG
1835 && insn
== find_next_ref (SET_DEST (PATTERN (temp
)), temp
)
1837 /* May skip USE or CLOBBER insns here
1838 for checking for opportunity, since we
1839 take care of them later. */
1840 && (temp1
= prev_active_insn (temp
))
1841 && GET_CODE (temp1
) == INSN
1842 && GET_CODE (PATTERN (temp1
)) == SET
1844 && SET_SRC (PATTERN (temp
)) == SET_DEST (PATTERN (temp1
))
1846 && (XEXP (SET_SRC (PATTERN (temp
)), 0)
1847 == SET_DEST (PATTERN (temp1
)))
1849 && CONSTANT_P (SET_SRC (PATTERN (temp1
)))
1850 /* If this isn't true, cse will do the job. */
1851 && ! no_labels_between_p (temp1
, temp
))
1853 /* Get the if_then_else from the condjump. */
1854 rtx choice
= SET_SRC (PATTERN (insn
));
1855 if (GET_CODE (choice
) == IF_THEN_ELSE
1856 && (GET_CODE (XEXP (choice
, 0)) == EQ
1857 || GET_CODE (XEXP (choice
, 0)) == NE
))
1859 int want_nonzero
= (GET_CODE (XEXP (choice
, 0)) == NE
);
1864 /* Get the place that condjump will jump to
1865 if it is reached from here. */
1866 if ((SET_SRC (PATTERN (temp1
)) != const0_rtx
)
1868 ultimate
= XEXP (choice
, 1);
1870 ultimate
= XEXP (choice
, 2);
1871 /* Get it as a CODE_LABEL. */
1872 if (ultimate
== pc_rtx
)
1873 ultimate
= get_label_after (insn
);
1875 /* Get the label out of the LABEL_REF. */
1876 ultimate
= XEXP (ultimate
, 0);
1878 /* Insert the jump immediately before TEMP, specifically
1879 after the label that is between TEMP1 and TEMP. */
1880 last_insn
= PREV_INSN (temp
);
1882 /* If we would be branching to the next insn, the jump
1883 would immediately be deleted and the re-inserted in
1884 a subsequent pass over the code. So don't do anything
1886 if (next_active_insn (last_insn
)
1887 != next_active_insn (ultimate
))
1889 emit_barrier_after (last_insn
);
1890 p
= emit_jump_insn_after (gen_jump (ultimate
),
1892 JUMP_LABEL (p
) = ultimate
;
1893 ++LABEL_NUSES (ultimate
);
1894 if (INSN_UID (ultimate
) < max_jump_chain
1895 && INSN_CODE (p
) < max_jump_chain
)
1897 jump_chain
[INSN_UID (p
)]
1898 = jump_chain
[INSN_UID (ultimate
)];
1899 jump_chain
[INSN_UID (ultimate
)] = p
;
1908 /* Detect a conditional jump jumping over an unconditional trap. */
1910 && this_is_condjump
&& ! this_is_simplejump
1911 && reallabelprev
!= 0
1912 && GET_CODE (reallabelprev
) == INSN
1913 && GET_CODE (PATTERN (reallabelprev
)) == TRAP_IF
1914 && TRAP_CONDITION (PATTERN (reallabelprev
)) == const_true_rtx
1915 && prev_active_insn (reallabelprev
) == insn
1916 && no_labels_between_p (insn
, reallabelprev
)
1917 && (temp2
= get_condition (insn
, &temp4
))
1918 && can_reverse_comparison_p (temp2
, insn
))
1920 rtx
new = gen_cond_trap (reverse_condition (GET_CODE (temp2
)),
1921 XEXP (temp2
, 0), XEXP (temp2
, 1),
1922 TRAP_CODE (PATTERN (reallabelprev
)));
1926 emit_insn_before (new, temp4
);
1927 delete_insn (reallabelprev
);
1933 /* Detect a jump jumping to an unconditional trap. */
1934 else if (HAVE_trap
&& this_is_condjump
1935 && (temp
= next_active_insn (JUMP_LABEL (insn
)))
1936 && GET_CODE (temp
) == INSN
1937 && GET_CODE (PATTERN (temp
)) == TRAP_IF
1938 && (this_is_simplejump
1939 || (temp2
= get_condition (insn
, &temp4
))))
1941 rtx tc
= TRAP_CONDITION (PATTERN (temp
));
1943 if (tc
== const_true_rtx
1944 || (! this_is_simplejump
&& rtx_equal_p (temp2
, tc
)))
1947 /* Replace an unconditional jump to a trap with a trap. */
1948 if (this_is_simplejump
)
1950 emit_barrier_after (emit_insn_before (gen_trap (), insn
));
1955 new = gen_cond_trap (GET_CODE (temp2
), XEXP (temp2
, 0),
1957 TRAP_CODE (PATTERN (temp
)));
1960 emit_insn_before (new, temp4
);
1966 /* If the trap condition and jump condition are mutually
1967 exclusive, redirect the jump to the following insn. */
1968 else if (GET_RTX_CLASS (GET_CODE (tc
)) == '<'
1969 && ! this_is_simplejump
1970 && swap_condition (GET_CODE (temp2
)) == GET_CODE (tc
)
1971 && rtx_equal_p (XEXP (tc
, 0), XEXP (temp2
, 0))
1972 && rtx_equal_p (XEXP (tc
, 1), XEXP (temp2
, 1))
1973 && redirect_jump (insn
, get_label_after (temp
)))
1982 /* Detect a jump to a jump. */
1984 /* Look for if (foo) bar; else break; */
1985 /* The insns look like this:
1986 insn = condjump label1;
1987 ...range1 (some insns)...
1990 ...range2 (some insns)...
1991 jump somewhere unconditionally
1994 rtx label1
= next_label (insn
);
1995 rtx range1end
= label1
? prev_active_insn (label1
) : 0;
1996 /* Don't do this optimization on the first round, so that
1997 jump-around-a-jump gets simplified before we ask here
1998 whether a jump is unconditional.
2000 Also don't do it when we are called after reload since
2001 it will confuse reorg. */
2003 && (reload_completed
? ! flag_delayed_branch
: 1)
2004 /* Make sure INSN is something we can invert. */
2005 && condjump_p (insn
)
2007 && JUMP_LABEL (insn
) == label1
2008 && LABEL_NUSES (label1
) == 1
2009 && GET_CODE (range1end
) == JUMP_INSN
2010 && simplejump_p (range1end
))
2012 rtx label2
= next_label (label1
);
2013 rtx range2end
= label2
? prev_active_insn (label2
) : 0;
2014 if (range1end
!= range2end
2015 && JUMP_LABEL (range1end
) == label2
2016 && GET_CODE (range2end
) == JUMP_INSN
2017 && GET_CODE (NEXT_INSN (range2end
)) == BARRIER
2018 /* Invert the jump condition, so we
2019 still execute the same insns in each case. */
2020 && invert_jump (insn
, label1
))
2022 rtx range1beg
= next_active_insn (insn
);
2023 rtx range2beg
= next_active_insn (label1
);
2024 rtx range1after
, range2after
;
2025 rtx range1before
, range2before
;
2028 /* Include in each range any notes before it, to be
2029 sure that we get the line number note if any, even
2030 if there are other notes here. */
2031 while (PREV_INSN (range1beg
)
2032 && GET_CODE (PREV_INSN (range1beg
)) == NOTE
)
2033 range1beg
= PREV_INSN (range1beg
);
2035 while (PREV_INSN (range2beg
)
2036 && GET_CODE (PREV_INSN (range2beg
)) == NOTE
)
2037 range2beg
= PREV_INSN (range2beg
);
2039 /* Don't move NOTEs for blocks or loops; shift them
2040 outside the ranges, where they'll stay put. */
2041 range1beg
= squeeze_notes (range1beg
, range1end
);
2042 range2beg
= squeeze_notes (range2beg
, range2end
);
2044 /* Get current surrounds of the 2 ranges. */
2045 range1before
= PREV_INSN (range1beg
);
2046 range2before
= PREV_INSN (range2beg
);
2047 range1after
= NEXT_INSN (range1end
);
2048 range2after
= NEXT_INSN (range2end
);
2050 /* Splice range2 where range1 was. */
2051 NEXT_INSN (range1before
) = range2beg
;
2052 PREV_INSN (range2beg
) = range1before
;
2053 NEXT_INSN (range2end
) = range1after
;
2054 PREV_INSN (range1after
) = range2end
;
2055 /* Splice range1 where range2 was. */
2056 NEXT_INSN (range2before
) = range1beg
;
2057 PREV_INSN (range1beg
) = range2before
;
2058 NEXT_INSN (range1end
) = range2after
;
2059 PREV_INSN (range2after
) = range1end
;
2061 /* Check for a loop end note between the end of
2062 range2, and the next code label. If there is one,
2063 then what we have really seen is
2064 if (foo) break; end_of_loop;
2065 and moved the break sequence outside the loop.
2066 We must move the LOOP_END note to where the
2067 loop really ends now, or we will confuse loop
2068 optimization. Stop if we find a LOOP_BEG note
2069 first, since we don't want to move the LOOP_END
2070 note in that case. */
2071 for (;range2after
!= label2
; range2after
= rangenext
)
2073 rangenext
= NEXT_INSN (range2after
);
2074 if (GET_CODE (range2after
) == NOTE
)
2076 if (NOTE_LINE_NUMBER (range2after
)
2077 == NOTE_INSN_LOOP_END
)
2079 NEXT_INSN (PREV_INSN (range2after
))
2081 PREV_INSN (rangenext
)
2082 = PREV_INSN (range2after
);
2083 PREV_INSN (range2after
)
2084 = PREV_INSN (range1beg
);
2085 NEXT_INSN (range2after
) = range1beg
;
2086 NEXT_INSN (PREV_INSN (range1beg
))
2088 PREV_INSN (range1beg
) = range2after
;
2090 else if (NOTE_LINE_NUMBER (range2after
)
2091 == NOTE_INSN_LOOP_BEG
)
2101 /* Now that the jump has been tensioned,
2102 try cross jumping: check for identical code
2103 before the jump and before its target label. */
2105 /* First, cross jumping of conditional jumps: */
2107 if (cross_jump
&& condjump_p (insn
))
2109 rtx newjpos
, newlpos
;
2110 rtx x
= prev_real_insn (JUMP_LABEL (insn
));
2112 /* A conditional jump may be crossjumped
2113 only if the place it jumps to follows
2114 an opposing jump that comes back here. */
2116 if (x
!= 0 && ! jump_back_p (x
, insn
))
2117 /* We have no opposing jump;
2118 cannot cross jump this insn. */
2122 /* TARGET is nonzero if it is ok to cross jump
2123 to code before TARGET. If so, see if matches. */
2125 find_cross_jump (insn
, x
, 2,
2126 &newjpos
, &newlpos
);
2130 do_cross_jump (insn
, newjpos
, newlpos
);
2131 /* Make the old conditional jump
2132 into an unconditional one. */
2133 SET_SRC (PATTERN (insn
))
2134 = gen_rtx_LABEL_REF (VOIDmode
, JUMP_LABEL (insn
));
2135 INSN_CODE (insn
) = -1;
2136 emit_barrier_after (insn
);
2137 /* Add to jump_chain unless this is a new label
2138 whose UID is too large. */
2139 if (INSN_UID (JUMP_LABEL (insn
)) < max_jump_chain
)
2141 jump_chain
[INSN_UID (insn
)]
2142 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
2143 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
2150 /* Cross jumping of unconditional jumps:
2151 a few differences. */
2153 if (cross_jump
&& simplejump_p (insn
))
2155 rtx newjpos
, newlpos
;
2160 /* TARGET is nonzero if it is ok to cross jump
2161 to code before TARGET. If so, see if matches. */
2162 find_cross_jump (insn
, JUMP_LABEL (insn
), 1,
2163 &newjpos
, &newlpos
);
2165 /* If cannot cross jump to code before the label,
2166 see if we can cross jump to another jump to
2168 /* Try each other jump to this label. */
2169 if (INSN_UID (JUMP_LABEL (insn
)) < max_uid
)
2170 for (target
= jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
2171 target
!= 0 && newjpos
== 0;
2172 target
= jump_chain
[INSN_UID (target
)])
2174 && JUMP_LABEL (target
) == JUMP_LABEL (insn
)
2175 /* Ignore TARGET if it's deleted. */
2176 && ! INSN_DELETED_P (target
))
2177 find_cross_jump (insn
, target
, 2,
2178 &newjpos
, &newlpos
);
2182 do_cross_jump (insn
, newjpos
, newlpos
);
2188 /* This code was dead in the previous jump.c! */
2189 if (cross_jump
&& GET_CODE (PATTERN (insn
)) == RETURN
)
2191 /* Return insns all "jump to the same place"
2192 so we can cross-jump between any two of them. */
2194 rtx newjpos
, newlpos
, target
;
2198 /* If cannot cross jump to code before the label,
2199 see if we can cross jump to another jump to
2201 /* Try each other jump to this label. */
2202 for (target
= jump_chain
[0];
2203 target
!= 0 && newjpos
== 0;
2204 target
= jump_chain
[INSN_UID (target
)])
2206 && ! INSN_DELETED_P (target
)
2207 && GET_CODE (PATTERN (target
)) == RETURN
)
2208 find_cross_jump (insn
, target
, 2,
2209 &newjpos
, &newlpos
);
2213 do_cross_jump (insn
, newjpos
, newlpos
);
2224 /* Delete extraneous line number notes.
2225 Note that two consecutive notes for different lines are not really
2226 extraneous. There should be some indication where that line belonged,
2227 even if it became empty. */
2232 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2233 if (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0)
2235 /* Delete this note if it is identical to previous note. */
2237 && NOTE_SOURCE_FILE (insn
) == NOTE_SOURCE_FILE (last_note
)
2238 && NOTE_LINE_NUMBER (insn
) == NOTE_LINE_NUMBER (last_note
))
2251 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2252 in front of it. If the machine allows it at this point (we might be
2253 after reload for a leaf routine), it will improve optimization for it
2254 to be there. We do this both here and at the start of this pass since
2255 the RETURN might have been deleted by some of our optimizations. */
2256 insn
= get_last_insn ();
2257 while (insn
&& GET_CODE (insn
) == NOTE
)
2258 insn
= PREV_INSN (insn
);
2260 if (insn
&& GET_CODE (insn
) != BARRIER
)
2262 emit_jump_insn (gen_return ());
2268 /* CAN_REACH_END is persistent for each function. Once set it should
2269 not be cleared. This is especially true for the case where we
2270 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
2271 the front-end before compiling each function. */
2272 if (calculate_can_reach_end (last_insn
, 0, 1))
2275 /* Show JUMP_CHAIN no longer valid. */
2279 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2280 notes whose labels don't occur in the insn any more. Returns the
2281 largest INSN_UID found. */
2286 int largest_uid
= 0;
2289 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2291 if (GET_CODE (insn
) == CODE_LABEL
)
2292 LABEL_NUSES (insn
) = (LABEL_PRESERVE_P (insn
) != 0);
2293 else if (GET_CODE (insn
) == JUMP_INSN
)
2294 JUMP_LABEL (insn
) = 0;
2295 else if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == CALL_INSN
)
2299 for (note
= REG_NOTES (insn
); note
; note
= next
)
2301 next
= XEXP (note
, 1);
2302 if (REG_NOTE_KIND (note
) == REG_LABEL
2303 && ! reg_mentioned_p (XEXP (note
, 0), PATTERN (insn
)))
2304 remove_note (insn
, note
);
2307 if (INSN_UID (insn
) > largest_uid
)
2308 largest_uid
= INSN_UID (insn
);
2314 /* Delete insns following barriers, up to next label.
2316 Also delete no-op jumps created by gcse. */
2318 delete_barrier_successors (f
)
2323 for (insn
= f
; insn
;)
2325 if (GET_CODE (insn
) == BARRIER
)
2327 insn
= NEXT_INSN (insn
);
2329 never_reached_warning (insn
);
2331 while (insn
!= 0 && GET_CODE (insn
) != CODE_LABEL
)
2333 if (GET_CODE (insn
) == NOTE
2334 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
2335 insn
= NEXT_INSN (insn
);
2337 insn
= delete_insn (insn
);
2339 /* INSN is now the code_label. */
2341 /* Also remove (set (pc) (pc)) insns which can be created by
2342 gcse. We eliminate such insns now to avoid having them
2343 cause problems later. */
2344 else if (GET_CODE (insn
) == JUMP_INSN
2345 && GET_CODE (PATTERN (insn
)) == SET
2346 && SET_SRC (PATTERN (insn
)) == pc_rtx
2347 && SET_DEST (PATTERN (insn
)) == pc_rtx
)
2348 insn
= delete_insn (insn
);
2351 insn
= NEXT_INSN (insn
);
2355 /* Mark the label each jump jumps to.
2356 Combine consecutive labels, and count uses of labels.
2358 For each label, make a chain (using `jump_chain')
2359 of all the *unconditional* jumps that jump to it;
2360 also make a chain of all returns.
2362 CROSS_JUMP indicates whether we are doing cross jumping
2363 and if we are whether we will be paying attention to
2364 death notes or not. */
2367 mark_all_labels (f
, cross_jump
)
2373 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2374 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
2376 mark_jump_label (PATTERN (insn
), insn
, cross_jump
);
2377 if (! INSN_DELETED_P (insn
) && GET_CODE (insn
) == JUMP_INSN
)
2379 if (JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
2381 jump_chain
[INSN_UID (insn
)]
2382 = jump_chain
[INSN_UID (JUMP_LABEL (insn
))];
2383 jump_chain
[INSN_UID (JUMP_LABEL (insn
))] = insn
;
2385 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2387 jump_chain
[INSN_UID (insn
)] = jump_chain
[0];
2388 jump_chain
[0] = insn
;
2394 /* Delete all labels already not referenced.
2395 Also find and return the last insn. */
2398 delete_unreferenced_labels (f
)
2401 rtx final
= NULL_RTX
;
2404 for (insn
= f
; insn
; )
2406 if (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NUSES (insn
) == 0)
2407 insn
= delete_insn (insn
);
2411 insn
= NEXT_INSN (insn
);
2418 /* Delete various simple forms of moves which have no necessary
2422 delete_noop_moves (f
)
2427 for (insn
= f
; insn
; )
2429 next
= NEXT_INSN (insn
);
2431 if (GET_CODE (insn
) == INSN
)
2433 register rtx body
= PATTERN (insn
);
2435 /* Combine stack_adjusts with following push_insns. */
2436 #ifdef PUSH_ROUNDING
2437 if (GET_CODE (body
) == SET
2438 && SET_DEST (body
) == stack_pointer_rtx
2439 && GET_CODE (SET_SRC (body
)) == PLUS
2440 && XEXP (SET_SRC (body
), 0) == stack_pointer_rtx
2441 && GET_CODE (XEXP (SET_SRC (body
), 1)) == CONST_INT
2442 && INTVAL (XEXP (SET_SRC (body
), 1)) > 0)
2445 rtx stack_adjust_insn
= insn
;
2446 int stack_adjust_amount
= INTVAL (XEXP (SET_SRC (body
), 1));
2447 int total_pushed
= 0;
2450 /* Find all successive push insns. */
2452 /* Don't convert more than three pushes;
2453 that starts adding too many displaced addresses
2454 and the whole thing starts becoming a losing
2459 p
= next_nonnote_insn (p
);
2460 if (p
== 0 || GET_CODE (p
) != INSN
)
2462 pbody
= PATTERN (p
);
2463 if (GET_CODE (pbody
) != SET
)
2465 dest
= SET_DEST (pbody
);
2466 /* Allow a no-op move between the adjust and the push. */
2467 if (GET_CODE (dest
) == REG
2468 && GET_CODE (SET_SRC (pbody
)) == REG
2469 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
2471 if (! (GET_CODE (dest
) == MEM
2472 && GET_CODE (XEXP (dest
, 0)) == POST_INC
2473 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
2476 if (total_pushed
+ GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)))
2477 > stack_adjust_amount
)
2479 total_pushed
+= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
2482 /* Discard the amount pushed from the stack adjust;
2483 maybe eliminate it entirely. */
2484 if (total_pushed
>= stack_adjust_amount
)
2486 delete_computation (stack_adjust_insn
);
2487 total_pushed
= stack_adjust_amount
;
2490 XEXP (SET_SRC (PATTERN (stack_adjust_insn
)), 1)
2491 = GEN_INT (stack_adjust_amount
- total_pushed
);
2493 /* Change the appropriate push insns to ordinary stores. */
2495 while (total_pushed
> 0)
2498 p
= next_nonnote_insn (p
);
2499 if (GET_CODE (p
) != INSN
)
2501 pbody
= PATTERN (p
);
2502 if (GET_CODE (pbody
) != SET
)
2504 dest
= SET_DEST (pbody
);
2505 /* Allow a no-op move between the adjust and the push. */
2506 if (GET_CODE (dest
) == REG
2507 && GET_CODE (SET_SRC (pbody
)) == REG
2508 && REGNO (dest
) == REGNO (SET_SRC (pbody
)))
2510 if (! (GET_CODE (dest
) == MEM
2511 && GET_CODE (XEXP (dest
, 0)) == POST_INC
2512 && XEXP (XEXP (dest
, 0), 0) == stack_pointer_rtx
))
2514 total_pushed
-= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody
)));
2515 /* If this push doesn't fully fit in the space
2516 of the stack adjust that we deleted,
2517 make another stack adjust here for what we
2518 didn't use up. There should be peepholes
2519 to recognize the resulting sequence of insns. */
2520 if (total_pushed
< 0)
2522 emit_insn_before (gen_add2_insn (stack_pointer_rtx
,
2523 GEN_INT (- total_pushed
)),
2528 = plus_constant (stack_pointer_rtx
, total_pushed
);
2533 /* Detect and delete no-op move instructions
2534 resulting from not allocating a parameter in a register. */
2536 if (GET_CODE (body
) == SET
2537 && (SET_DEST (body
) == SET_SRC (body
)
2538 || (GET_CODE (SET_DEST (body
)) == MEM
2539 && GET_CODE (SET_SRC (body
)) == MEM
2540 && rtx_equal_p (SET_SRC (body
), SET_DEST (body
))))
2541 && ! (GET_CODE (SET_DEST (body
)) == MEM
2542 && MEM_VOLATILE_P (SET_DEST (body
)))
2543 && ! (GET_CODE (SET_SRC (body
)) == MEM
2544 && MEM_VOLATILE_P (SET_SRC (body
))))
2545 delete_computation (insn
);
2547 /* Detect and ignore no-op move instructions
2548 resulting from smart or fortuitous register allocation. */
2550 else if (GET_CODE (body
) == SET
)
2552 int sreg
= true_regnum (SET_SRC (body
));
2553 int dreg
= true_regnum (SET_DEST (body
));
2555 if (sreg
== dreg
&& sreg
>= 0)
2557 else if (sreg
>= 0 && dreg
>= 0)
2560 rtx tem
= find_equiv_reg (NULL_RTX
, insn
, 0,
2561 sreg
, NULL_PTR
, dreg
,
2562 GET_MODE (SET_SRC (body
)));
2565 && GET_MODE (tem
) == GET_MODE (SET_DEST (body
)))
2567 /* DREG may have been the target of a REG_DEAD note in
2568 the insn which makes INSN redundant. If so, reorg
2569 would still think it is dead. So search for such a
2570 note and delete it if we find it. */
2571 if (! find_regno_note (insn
, REG_UNUSED
, dreg
))
2572 for (trial
= prev_nonnote_insn (insn
);
2573 trial
&& GET_CODE (trial
) != CODE_LABEL
;
2574 trial
= prev_nonnote_insn (trial
))
2575 if (find_regno_note (trial
, REG_DEAD
, dreg
))
2577 remove_death (dreg
, trial
);
2581 /* Deleting insn could lose a death-note for SREG. */
2582 if ((trial
= find_regno_note (insn
, REG_DEAD
, sreg
)))
2584 /* Change this into a USE so that we won't emit
2585 code for it, but still can keep the note. */
2587 = gen_rtx_USE (VOIDmode
, XEXP (trial
, 0));
2588 INSN_CODE (insn
) = -1;
2589 /* Remove all reg notes but the REG_DEAD one. */
2590 REG_NOTES (insn
) = trial
;
2591 XEXP (trial
, 1) = NULL_RTX
;
2597 else if (dreg
>= 0 && CONSTANT_P (SET_SRC (body
))
2598 && find_equiv_reg (SET_SRC (body
), insn
, 0, dreg
,
2600 GET_MODE (SET_DEST (body
))))
2602 /* This handles the case where we have two consecutive
2603 assignments of the same constant to pseudos that didn't
2604 get a hard reg. Each SET from the constant will be
2605 converted into a SET of the spill register and an
2606 output reload will be made following it. This produces
2607 two loads of the same constant into the same spill
2612 /* Look back for a death note for the first reg.
2613 If there is one, it is no longer accurate. */
2614 while (in_insn
&& GET_CODE (in_insn
) != CODE_LABEL
)
2616 if ((GET_CODE (in_insn
) == INSN
2617 || GET_CODE (in_insn
) == JUMP_INSN
)
2618 && find_regno_note (in_insn
, REG_DEAD
, dreg
))
2620 remove_death (dreg
, in_insn
);
2623 in_insn
= PREV_INSN (in_insn
);
2626 /* Delete the second load of the value. */
2630 else if (GET_CODE (body
) == PARALLEL
)
2632 /* If each part is a set between two identical registers or
2633 a USE or CLOBBER, delete the insn. */
2637 for (i
= XVECLEN (body
, 0) - 1; i
>= 0; i
--)
2639 tem
= XVECEXP (body
, 0, i
);
2640 if (GET_CODE (tem
) == USE
|| GET_CODE (tem
) == CLOBBER
)
2643 if (GET_CODE (tem
) != SET
2644 || (sreg
= true_regnum (SET_SRC (tem
))) < 0
2645 || (dreg
= true_regnum (SET_DEST (tem
))) < 0
2653 /* Also delete insns to store bit fields if they are no-ops. */
2654 /* Not worth the hair to detect this in the big-endian case. */
2655 else if (! BYTES_BIG_ENDIAN
2656 && GET_CODE (body
) == SET
2657 && GET_CODE (SET_DEST (body
)) == ZERO_EXTRACT
2658 && XEXP (SET_DEST (body
), 2) == const0_rtx
2659 && XEXP (SET_DEST (body
), 0) == SET_SRC (body
)
2660 && ! (GET_CODE (SET_SRC (body
)) == MEM
2661 && MEM_VOLATILE_P (SET_SRC (body
))))
2668 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2669 If so indicate that this function can drop off the end by returning
2672 CHECK_DELETED indicates whether we must check if the note being
2673 searched for has the deleted flag set.
2675 DELETE_FINAL_NOTE indicates whether we should delete the note
2679 calculate_can_reach_end (last
, check_deleted
, delete_final_note
)
2682 int delete_final_note
;
2687 while (insn
!= NULL_RTX
)
2691 /* One label can follow the end-note: the return label. */
2692 if (GET_CODE (insn
) == CODE_LABEL
&& n_labels
-- > 0)
2694 /* Ordinary insns can follow it if returning a structure. */
2695 else if (GET_CODE (insn
) == INSN
)
2697 /* If machine uses explicit RETURN insns, no epilogue,
2698 then one of them follows the note. */
2699 else if (GET_CODE (insn
) == JUMP_INSN
2700 && GET_CODE (PATTERN (insn
)) == RETURN
)
2702 /* A barrier can follow the return insn. */
2703 else if (GET_CODE (insn
) == BARRIER
)
2705 /* Other kinds of notes can follow also. */
2706 else if (GET_CODE (insn
) == NOTE
2707 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_FUNCTION_END
)
2713 insn
= PREV_INSN (insn
);
2716 /* See if we backed up to the appropriate type of note. */
2717 if (insn
!= NULL_RTX
2718 && GET_CODE (insn
) == NOTE
2719 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_END
2720 && (check_deleted
== 0
2721 || ! INSN_DELETED_P (insn
)))
2723 if (delete_final_note
)
2731 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2732 jump. Assume that this unconditional jump is to the exit test code. If
2733 the code is sufficiently simple, make a copy of it before INSN,
2734 followed by a jump to the exit of the loop. Then delete the unconditional
2737 Return 1 if we made the change, else 0.
2739 This is only safe immediately after a regscan pass because it uses the
2740 values of regno_first_uid and regno_last_uid. */
2743 duplicate_loop_exit_test (loop_start
)
2746 rtx insn
, set
, reg
, p
, link
;
2747 rtx copy
= 0, first_copy
= 0;
2749 rtx exitcode
= NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start
)));
2751 int max_reg
= max_reg_num ();
2754 /* Scan the exit code. We do not perform this optimization if any insn:
2758 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2759 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2760 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2763 We also do not do this if we find an insn with ASM_OPERANDS. While
2764 this restriction should not be necessary, copying an insn with
2765 ASM_OPERANDS can confuse asm_noperands in some cases.
2767 Also, don't do this if the exit code is more than 20 insns. */
2769 for (insn
= exitcode
;
2771 && ! (GET_CODE (insn
) == NOTE
2772 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
2773 insn
= NEXT_INSN (insn
))
2775 switch (GET_CODE (insn
))
2781 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2782 a jump immediately after the loop start that branches outside
2783 the loop but within an outer loop, near the exit test.
2784 If we copied this exit test and created a phony
2785 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2786 before the exit test look like these could be safely moved
2787 out of the loop even if they actually may be never executed.
2788 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2790 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2791 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
)
2795 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2796 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
))
2797 /* If we were to duplicate this code, we would not move
2798 the BLOCK notes, and so debugging the moved code would
2799 be difficult. Thus, we only move the code with -O2 or
2806 /* The code below would grossly mishandle REG_WAS_0 notes,
2807 so get rid of them here. */
2808 while ((p
= find_reg_note (insn
, REG_WAS_0
, NULL_RTX
)) != 0)
2809 remove_note (insn
, p
);
2810 if (++num_insns
> 20
2811 || find_reg_note (insn
, REG_RETVAL
, NULL_RTX
)
2812 || find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2820 /* Unless INSN is zero, we can do the optimization. */
2826 /* See if any insn sets a register only used in the loop exit code and
2827 not a user variable. If so, replace it with a new register. */
2828 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2829 if (GET_CODE (insn
) == INSN
2830 && (set
= single_set (insn
)) != 0
2831 && ((reg
= SET_DEST (set
), GET_CODE (reg
) == REG
)
2832 || (GET_CODE (reg
) == SUBREG
2833 && (reg
= SUBREG_REG (reg
), GET_CODE (reg
) == REG
)))
2834 && REGNO (reg
) >= FIRST_PSEUDO_REGISTER
2835 && REGNO_FIRST_UID (REGNO (reg
)) == INSN_UID (insn
))
2837 for (p
= NEXT_INSN (insn
); p
!= lastexit
; p
= NEXT_INSN (p
))
2838 if (REGNO_LAST_UID (REGNO (reg
)) == INSN_UID (p
))
2843 /* We can do the replacement. Allocate reg_map if this is the
2844 first replacement we found. */
2847 reg_map
= (rtx
*) alloca (max_reg
* sizeof (rtx
));
2848 bzero ((char *) reg_map
, max_reg
* sizeof (rtx
));
2851 REG_LOOP_TEST_P (reg
) = 1;
2853 reg_map
[REGNO (reg
)] = gen_reg_rtx (GET_MODE (reg
));
2857 /* Now copy each insn. */
2858 for (insn
= exitcode
; insn
!= lastexit
; insn
= NEXT_INSN (insn
))
2860 switch (GET_CODE (insn
))
2863 copy
= emit_barrier_before (loop_start
);
2866 /* Only copy line-number notes. */
2867 if (NOTE_LINE_NUMBER (insn
) >= 0)
2869 copy
= emit_note_before (NOTE_LINE_NUMBER (insn
), loop_start
);
2870 NOTE_SOURCE_FILE (copy
) = NOTE_SOURCE_FILE (insn
);
2875 copy
= emit_insn_before (copy_insn (PATTERN (insn
)), loop_start
);
2877 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2879 mark_jump_label (PATTERN (copy
), copy
, 0);
2881 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2883 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2884 if (REG_NOTE_KIND (link
) != REG_LABEL
)
2886 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link
),
2889 if (reg_map
&& REG_NOTES (copy
))
2890 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2894 copy
= emit_jump_insn_before (copy_insn (PATTERN (insn
)), loop_start
);
2896 replace_regs (PATTERN (copy
), reg_map
, max_reg
, 1);
2897 mark_jump_label (PATTERN (copy
), copy
, 0);
2898 if (REG_NOTES (insn
))
2900 REG_NOTES (copy
) = copy_insn_1 (REG_NOTES (insn
));
2902 replace_regs (REG_NOTES (copy
), reg_map
, max_reg
, 1);
2905 /* If this is a simple jump, add it to the jump chain. */
2907 if (INSN_UID (copy
) < max_jump_chain
&& JUMP_LABEL (copy
)
2908 && simplejump_p (copy
))
2910 jump_chain
[INSN_UID (copy
)]
2911 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2912 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2920 /* Record the first insn we copied. We need it so that we can
2921 scan the copied insns for new pseudo registers. */
2926 /* Now clean up by emitting a jump to the end label and deleting the jump
2927 at the start of the loop. */
2928 if (! copy
|| GET_CODE (copy
) != BARRIER
)
2930 copy
= emit_jump_insn_before (gen_jump (get_label_after (insn
)),
2933 /* Record the first insn we copied. We need it so that we can
2934 scan the copied insns for new pseudo registers. This may not
2935 be strictly necessary since we should have copied at least one
2936 insn above. But I am going to be safe. */
2940 mark_jump_label (PATTERN (copy
), copy
, 0);
2941 if (INSN_UID (copy
) < max_jump_chain
2942 && INSN_UID (JUMP_LABEL (copy
)) < max_jump_chain
)
2944 jump_chain
[INSN_UID (copy
)]
2945 = jump_chain
[INSN_UID (JUMP_LABEL (copy
))];
2946 jump_chain
[INSN_UID (JUMP_LABEL (copy
))] = copy
;
2948 emit_barrier_before (loop_start
);
2951 /* Now scan from the first insn we copied to the last insn we copied
2952 (copy) for new pseudo registers. Do this after the code to jump to
2953 the end label since that might create a new pseudo too. */
2954 reg_scan_update (first_copy
, copy
, max_reg
);
2956 /* Mark the exit code as the virtual top of the converted loop. */
2957 emit_note_before (NOTE_INSN_LOOP_VTOP
, exitcode
);
2959 delete_insn (next_nonnote_insn (loop_start
));
2964 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2965 loop-end notes between START and END out before START. Assume that
2966 END is not such a note. START may be such a note. Returns the value
2967 of the new starting insn, which may be different if the original start
2971 squeeze_notes (start
, end
)
2977 for (insn
= start
; insn
!= end
; insn
= next
)
2979 next
= NEXT_INSN (insn
);
2980 if (GET_CODE (insn
) == NOTE
2981 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
2982 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
2983 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
2984 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
2985 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_CONT
2986 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_VTOP
))
2992 rtx prev
= PREV_INSN (insn
);
2993 PREV_INSN (insn
) = PREV_INSN (start
);
2994 NEXT_INSN (insn
) = start
;
2995 NEXT_INSN (PREV_INSN (insn
)) = insn
;
2996 PREV_INSN (NEXT_INSN (insn
)) = insn
;
2997 NEXT_INSN (prev
) = next
;
2998 PREV_INSN (next
) = prev
;
3006 /* Compare the instructions before insn E1 with those before E2
3007 to find an opportunity for cross jumping.
3008 (This means detecting identical sequences of insns followed by
3009 jumps to the same place, or followed by a label and a jump
3010 to that label, and replacing one with a jump to the other.)
3012 Assume E1 is a jump that jumps to label E2
3013 (that is not always true but it might as well be).
3014 Find the longest possible equivalent sequences
3015 and store the first insns of those sequences into *F1 and *F2.
3016 Store zero there if no equivalent preceding instructions are found.
3018 We give up if we find a label in stream 1.
3019 Actually we could transfer that label into stream 2. */
3022 find_cross_jump (e1
, e2
, minimum
, f1
, f2
)
3027 register rtx i1
= e1
, i2
= e2
;
3028 register rtx p1
, p2
;
3031 rtx last1
= 0, last2
= 0;
3032 rtx afterlast1
= 0, afterlast2
= 0;
3039 i1
= prev_nonnote_insn (i1
);
3041 i2
= PREV_INSN (i2
);
3042 while (i2
&& (GET_CODE (i2
) == NOTE
|| GET_CODE (i2
) == CODE_LABEL
))
3043 i2
= PREV_INSN (i2
);
3048 /* Don't allow the range of insns preceding E1 or E2
3049 to include the other (E2 or E1). */
3050 if (i2
== e1
|| i1
== e2
)
3053 /* If we will get to this code by jumping, those jumps will be
3054 tensioned to go directly to the new label (before I2),
3055 so this cross-jumping won't cost extra. So reduce the minimum. */
3056 if (GET_CODE (i1
) == CODE_LABEL
)
3062 if (i2
== 0 || GET_CODE (i1
) != GET_CODE (i2
))
3065 /* Avoid moving insns across EH regions if either of the insns
3068 && (asynchronous_exceptions
|| GET_CODE (i1
) == CALL_INSN
)
3069 && !in_same_eh_region (i1
, i2
))
3075 /* If this is a CALL_INSN, compare register usage information.
3076 If we don't check this on stack register machines, the two
3077 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3078 numbers of stack registers in the same basic block.
3079 If we don't check this on machines with delay slots, a delay slot may
3080 be filled that clobbers a parameter expected by the subroutine.
3082 ??? We take the simple route for now and assume that if they're
3083 equal, they were constructed identically. */
3085 if (GET_CODE (i1
) == CALL_INSN
3086 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1
),
3087 CALL_INSN_FUNCTION_USAGE (i2
)))
3091 /* If cross_jump_death_matters is not 0, the insn's mode
3092 indicates whether or not the insn contains any stack-like
3095 if (!lose
&& cross_jump_death_matters
&& stack_regs_mentioned (i1
))
3097 /* If register stack conversion has already been done, then
3098 death notes must also be compared before it is certain that
3099 the two instruction streams match. */
3102 HARD_REG_SET i1_regset
, i2_regset
;
3104 CLEAR_HARD_REG_SET (i1_regset
);
3105 CLEAR_HARD_REG_SET (i2_regset
);
3107 for (note
= REG_NOTES (i1
); note
; note
= XEXP (note
, 1))
3108 if (REG_NOTE_KIND (note
) == REG_DEAD
3109 && STACK_REG_P (XEXP (note
, 0)))
3110 SET_HARD_REG_BIT (i1_regset
, REGNO (XEXP (note
, 0)));
3112 for (note
= REG_NOTES (i2
); note
; note
= XEXP (note
, 1))
3113 if (REG_NOTE_KIND (note
) == REG_DEAD
3114 && STACK_REG_P (XEXP (note
, 0)))
3115 SET_HARD_REG_BIT (i2_regset
, REGNO (XEXP (note
, 0)));
3117 GO_IF_HARD_REG_EQUAL (i1_regset
, i2_regset
, done
);
3126 /* Don't allow old-style asm or volatile extended asms to be accepted
3127 for cross jumping purposes. It is conceptually correct to allow
3128 them, since cross-jumping preserves the dynamic instruction order
3129 even though it is changing the static instruction order. However,
3130 if an asm is being used to emit an assembler pseudo-op, such as
3131 the MIPS `.set reorder' pseudo-op, then the static instruction order
3132 matters and it must be preserved. */
3133 if (GET_CODE (p1
) == ASM_INPUT
|| GET_CODE (p2
) == ASM_INPUT
3134 || (GET_CODE (p1
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p1
))
3135 || (GET_CODE (p2
) == ASM_OPERANDS
&& MEM_VOLATILE_P (p2
)))
3138 if (lose
|| GET_CODE (p1
) != GET_CODE (p2
)
3139 || ! rtx_renumbered_equal_p (p1
, p2
))
3141 /* The following code helps take care of G++ cleanups. */
3145 if (!lose
&& GET_CODE (p1
) == GET_CODE (p2
)
3146 && ((equiv1
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
)) != 0
3147 || (equiv1
= find_reg_note (i1
, REG_EQUIV
, NULL_RTX
)) != 0)
3148 && ((equiv2
= find_reg_note (i2
, REG_EQUAL
, NULL_RTX
)) != 0
3149 || (equiv2
= find_reg_note (i2
, REG_EQUIV
, NULL_RTX
)) != 0)
3150 /* If the equivalences are not to a constant, they may
3151 reference pseudos that no longer exist, so we can't
3153 && CONSTANT_P (XEXP (equiv1
, 0))
3154 && rtx_equal_p (XEXP (equiv1
, 0), XEXP (equiv2
, 0)))
3156 rtx s1
= single_set (i1
);
3157 rtx s2
= single_set (i2
);
3158 if (s1
!= 0 && s2
!= 0
3159 && rtx_renumbered_equal_p (SET_DEST (s1
), SET_DEST (s2
)))
3161 validate_change (i1
, &SET_SRC (s1
), XEXP (equiv1
, 0), 1);
3162 validate_change (i2
, &SET_SRC (s2
), XEXP (equiv2
, 0), 1);
3163 if (! rtx_renumbered_equal_p (p1
, p2
))
3165 else if (apply_change_group ())
3170 /* Insns fail to match; cross jumping is limited to the following
3174 /* Don't allow the insn after a compare to be shared by
3175 cross-jumping unless the compare is also shared.
3176 Here, if either of these non-matching insns is a compare,
3177 exclude the following insn from possible cross-jumping. */
3178 if (sets_cc0_p (p1
) || sets_cc0_p (p2
))
3179 last1
= afterlast1
, last2
= afterlast2
, ++minimum
;
3182 /* If cross-jumping here will feed a jump-around-jump
3183 optimization, this jump won't cost extra, so reduce
3185 if (GET_CODE (i1
) == JUMP_INSN
3187 && prev_real_insn (JUMP_LABEL (i1
)) == e1
)
3193 if (GET_CODE (p1
) != USE
&& GET_CODE (p1
) != CLOBBER
)
3195 /* Ok, this insn is potentially includable in a cross-jump here. */
3196 afterlast1
= last1
, afterlast2
= last2
;
3197 last1
= i1
, last2
= i2
, --minimum
;
3201 if (minimum
<= 0 && last1
!= 0 && last1
!= e1
)
3202 *f1
= last1
, *f2
= last2
;
3206 do_cross_jump (insn
, newjpos
, newlpos
)
3207 rtx insn
, newjpos
, newlpos
;
3209 /* Find an existing label at this point
3210 or make a new one if there is none. */
3211 register rtx label
= get_label_before (newlpos
);
3213 /* Make the same jump insn jump to the new point. */
3214 if (GET_CODE (PATTERN (insn
)) == RETURN
)
3216 /* Remove from jump chain of returns. */
3217 delete_from_jump_chain (insn
);
3218 /* Change the insn. */
3219 PATTERN (insn
) = gen_jump (label
);
3220 INSN_CODE (insn
) = -1;
3221 JUMP_LABEL (insn
) = label
;
3222 LABEL_NUSES (label
)++;
3223 /* Add to new the jump chain. */
3224 if (INSN_UID (label
) < max_jump_chain
3225 && INSN_UID (insn
) < max_jump_chain
)
3227 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (label
)];
3228 jump_chain
[INSN_UID (label
)] = insn
;
3232 redirect_jump (insn
, label
);
3234 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
3235 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
3236 the NEWJPOS stream. */
3238 while (newjpos
!= insn
)
3242 for (lnote
= REG_NOTES (newlpos
); lnote
; lnote
= XEXP (lnote
, 1))
3243 if ((REG_NOTE_KIND (lnote
) == REG_EQUAL
3244 || REG_NOTE_KIND (lnote
) == REG_EQUIV
)
3245 && ! find_reg_note (newjpos
, REG_EQUAL
, XEXP (lnote
, 0))
3246 && ! find_reg_note (newjpos
, REG_EQUIV
, XEXP (lnote
, 0)))
3247 remove_note (newlpos
, lnote
);
3249 delete_insn (newjpos
);
3250 newjpos
= next_real_insn (newjpos
);
3251 newlpos
= next_real_insn (newlpos
);
3255 /* Return the label before INSN, or put a new label there. */
3258 get_label_before (insn
)
3263 /* Find an existing label at this point
3264 or make a new one if there is none. */
3265 label
= prev_nonnote_insn (insn
);
3267 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
3269 rtx prev
= PREV_INSN (insn
);
3271 label
= gen_label_rtx ();
3272 emit_label_after (label
, prev
);
3273 LABEL_NUSES (label
) = 0;
3278 /* Return the label after INSN, or put a new label there. */
3281 get_label_after (insn
)
3286 /* Find an existing label at this point
3287 or make a new one if there is none. */
3288 label
= next_nonnote_insn (insn
);
3290 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
3292 label
= gen_label_rtx ();
3293 emit_label_after (label
, insn
);
3294 LABEL_NUSES (label
) = 0;
3299 /* Return 1 if INSN is a jump that jumps to right after TARGET
3300 only on the condition that TARGET itself would drop through.
3301 Assumes that TARGET is a conditional jump. */
3304 jump_back_p (insn
, target
)
3308 enum rtx_code codei
, codet
;
3310 if (simplejump_p (insn
) || ! condjump_p (insn
)
3311 || simplejump_p (target
)
3312 || target
!= prev_real_insn (JUMP_LABEL (insn
)))
3315 cinsn
= XEXP (SET_SRC (PATTERN (insn
)), 0);
3316 ctarget
= XEXP (SET_SRC (PATTERN (target
)), 0);
3318 codei
= GET_CODE (cinsn
);
3319 codet
= GET_CODE (ctarget
);
3321 if (XEXP (SET_SRC (PATTERN (insn
)), 1) == pc_rtx
)
3323 if (! can_reverse_comparison_p (cinsn
, insn
))
3325 codei
= reverse_condition (codei
);
3328 if (XEXP (SET_SRC (PATTERN (target
)), 2) == pc_rtx
)
3330 if (! can_reverse_comparison_p (ctarget
, target
))
3332 codet
= reverse_condition (codet
);
3335 return (codei
== codet
3336 && rtx_renumbered_equal_p (XEXP (cinsn
, 0), XEXP (ctarget
, 0))
3337 && rtx_renumbered_equal_p (XEXP (cinsn
, 1), XEXP (ctarget
, 1)));
3340 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3341 return non-zero if it is safe to reverse this comparison. It is if our
3342 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3343 this is known to be an integer comparison. */
3346 can_reverse_comparison_p (comparison
, insn
)
3352 /* If this is not actually a comparison, we can't reverse it. */
3353 if (GET_RTX_CLASS (GET_CODE (comparison
)) != '<')
3356 if (TARGET_FLOAT_FORMAT
!= IEEE_FLOAT_FORMAT
3357 /* If this is an NE comparison, it is safe to reverse it to an EQ
3358 comparison and vice versa, even for floating point. If no operands
3359 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3360 always false and NE is always true, so the reversal is also valid. */
3362 || GET_CODE (comparison
) == NE
3363 || GET_CODE (comparison
) == EQ
)
3366 arg0
= XEXP (comparison
, 0);
3368 /* Make sure ARG0 is one of the actual objects being compared. If we
3369 can't do this, we can't be sure the comparison can be reversed.
3371 Handle cc0 and a MODE_CC register. */
3372 if ((GET_CODE (arg0
) == REG
&& GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
)
3378 rtx prev
= prev_nonnote_insn (insn
);
3381 /* First see if the condition code mode alone if enough to say we can
3382 reverse the condition. If not, then search backwards for a set of
3383 ARG0. We do not need to check for an insn clobbering it since valid
3384 code will contain set a set with no intervening clobber. But
3385 stop when we reach a label. */
3386 #ifdef REVERSIBLE_CC_MODE
3387 if (GET_MODE_CLASS (GET_MODE (arg0
)) == MODE_CC
3388 && REVERSIBLE_CC_MODE (GET_MODE (arg0
)))
3392 for (prev
= prev_nonnote_insn (insn
);
3393 prev
!= 0 && GET_CODE (prev
) != CODE_LABEL
;
3394 prev
= prev_nonnote_insn (prev
))
3395 if ((set
= single_set (prev
)) != 0
3396 && rtx_equal_p (SET_DEST (set
), arg0
))
3398 arg0
= SET_SRC (set
);
3400 if (GET_CODE (arg0
) == COMPARE
)
3401 arg0
= XEXP (arg0
, 0);
3406 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3407 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3408 return (GET_CODE (arg0
) == CONST_INT
3409 || (GET_MODE (arg0
) != VOIDmode
3410 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_CC
3411 && GET_MODE_CLASS (GET_MODE (arg0
)) != MODE_FLOAT
));
3414 /* Given an rtx-code for a comparison, return the code
3415 for the negated comparison.
3416 WATCH OUT! reverse_condition is not safe to use on a jump
3417 that might be acting on the results of an IEEE floating point comparison,
3418 because of the special treatment of non-signaling nans in comparisons.
3419 Use can_reverse_comparison_p to be sure. */
3422 reverse_condition (code
)
3463 /* Similar, but return the code when two operands of a comparison are swapped.
3464 This IS safe for IEEE floating-point. */
3467 swap_condition (code
)
3506 /* Given a comparison CODE, return the corresponding unsigned comparison.
3507 If CODE is an equality comparison or already an unsigned comparison,
3508 CODE is returned. */
3511 unsigned_condition (code
)
3541 /* Similarly, return the signed version of a comparison. */
3544 signed_condition (code
)
3574 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3575 truth of CODE1 implies the truth of CODE2. */
3578 comparison_dominates_p (code1
, code2
)
3579 enum rtx_code code1
, code2
;
3587 if (code2
== LE
|| code2
== LEU
|| code2
== GE
|| code2
== GEU
)
3592 if (code2
== LE
|| code2
== NE
)
3597 if (code2
== GE
|| code2
== NE
)
3602 if (code2
== LEU
|| code2
== NE
)
3607 if (code2
== GEU
|| code2
== NE
)
3618 /* Return 1 if INSN is an unconditional jump and nothing else. */
3624 return (GET_CODE (insn
) == JUMP_INSN
3625 && GET_CODE (PATTERN (insn
)) == SET
3626 && GET_CODE (SET_DEST (PATTERN (insn
))) == PC
3627 && GET_CODE (SET_SRC (PATTERN (insn
))) == LABEL_REF
);
3630 /* Return nonzero if INSN is a (possibly) conditional jump
3631 and nothing more. */
3637 register rtx x
= PATTERN (insn
);
3639 if (GET_CODE (x
) != SET
3640 || GET_CODE (SET_DEST (x
)) != PC
)
3644 if (GET_CODE (x
) == LABEL_REF
)
3646 else return (GET_CODE (x
) == IF_THEN_ELSE
3647 && ((GET_CODE (XEXP (x
, 2)) == PC
3648 && (GET_CODE (XEXP (x
, 1)) == LABEL_REF
3649 || GET_CODE (XEXP (x
, 1)) == RETURN
))
3650 || (GET_CODE (XEXP (x
, 1)) == PC
3651 && (GET_CODE (XEXP (x
, 2)) == LABEL_REF
3652 || GET_CODE (XEXP (x
, 2)) == RETURN
))));
3657 /* Return nonzero if INSN is a (possibly) conditional jump inside a
3661 condjump_in_parallel_p (insn
)
3664 register rtx x
= PATTERN (insn
);
3666 if (GET_CODE (x
) != PARALLEL
)
3669 x
= XVECEXP (x
, 0, 0);
3671 if (GET_CODE (x
) != SET
)
3673 if (GET_CODE (SET_DEST (x
)) != PC
)
3675 if (GET_CODE (SET_SRC (x
)) == LABEL_REF
)
3677 if (GET_CODE (SET_SRC (x
)) != IF_THEN_ELSE
)
3679 if (XEXP (SET_SRC (x
), 2) == pc_rtx
3680 && (GET_CODE (XEXP (SET_SRC (x
), 1)) == LABEL_REF
3681 || GET_CODE (XEXP (SET_SRC (x
), 1)) == RETURN
))
3683 if (XEXP (SET_SRC (x
), 1) == pc_rtx
3684 && (GET_CODE (XEXP (SET_SRC (x
), 2)) == LABEL_REF
3685 || GET_CODE (XEXP (SET_SRC (x
), 2)) == RETURN
))
3690 /* Return the label of a conditional jump. */
3693 condjump_label (insn
)
3696 register rtx x
= PATTERN (insn
);
3698 if (GET_CODE (x
) == PARALLEL
)
3699 x
= XVECEXP (x
, 0, 0);
3700 if (GET_CODE (x
) != SET
)
3702 if (GET_CODE (SET_DEST (x
)) != PC
)
3705 if (GET_CODE (x
) == LABEL_REF
)
3707 if (GET_CODE (x
) != IF_THEN_ELSE
)
3709 if (XEXP (x
, 2) == pc_rtx
&& GET_CODE (XEXP (x
, 1)) == LABEL_REF
)
3711 if (XEXP (x
, 1) == pc_rtx
&& GET_CODE (XEXP (x
, 2)) == LABEL_REF
)
3716 /* Return true if INSN is a (possibly conditional) return insn. */
3719 returnjump_p_1 (loc
, data
)
3721 void *data ATTRIBUTE_UNUSED
;
3724 return GET_CODE (x
) == RETURN
;
3731 return for_each_rtx (&PATTERN (insn
), returnjump_p_1
, NULL
);
3734 /* Return true if INSN is a jump that only transfers control and
3743 if (GET_CODE (insn
) != JUMP_INSN
)
3746 set
= single_set (insn
);
3749 if (GET_CODE (SET_DEST (set
)) != PC
)
3751 if (side_effects_p (SET_SRC (set
)))
3759 /* Return 1 if X is an RTX that does nothing but set the condition codes
3760 and CLOBBER or USE registers.
3761 Return -1 if X does explicitly set the condition codes,
3762 but also does other things. */
3766 rtx x ATTRIBUTE_UNUSED
;
3768 if (GET_CODE (x
) == SET
&& SET_DEST (x
) == cc0_rtx
)
3770 if (GET_CODE (x
) == PARALLEL
)
3774 int other_things
= 0;
3775 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
3777 if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
3778 && SET_DEST (XVECEXP (x
, 0, i
)) == cc0_rtx
)
3780 else if (GET_CODE (XVECEXP (x
, 0, i
)) == SET
)
3783 return ! sets_cc0
? 0 : other_things
? -1 : 1;
3789 /* Follow any unconditional jump at LABEL;
3790 return the ultimate label reached by any such chain of jumps.
3791 If LABEL is not followed by a jump, return LABEL.
3792 If the chain loops or we can't find end, return LABEL,
3793 since that tells caller to avoid changing the insn.
3795 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3796 a USE or CLOBBER. */
3799 follow_jumps (label
)
3804 register rtx value
= label
;
3809 && (insn
= next_active_insn (value
)) != 0
3810 && GET_CODE (insn
) == JUMP_INSN
3811 && ((JUMP_LABEL (insn
) != 0 && simplejump_p (insn
))
3812 || GET_CODE (PATTERN (insn
)) == RETURN
)
3813 && (next
= NEXT_INSN (insn
))
3814 && GET_CODE (next
) == BARRIER
);
3817 /* Don't chain through the insn that jumps into a loop
3818 from outside the loop,
3819 since that would create multiple loop entry jumps
3820 and prevent loop optimization. */
3822 if (!reload_completed
)
3823 for (tem
= value
; tem
!= insn
; tem
= NEXT_INSN (tem
))
3824 if (GET_CODE (tem
) == NOTE
3825 && (NOTE_LINE_NUMBER (tem
) == NOTE_INSN_LOOP_BEG
3826 /* ??? Optional. Disables some optimizations, but makes
3827 gcov output more accurate with -O. */
3828 || (flag_test_coverage
&& NOTE_LINE_NUMBER (tem
) > 0)))
3831 /* If we have found a cycle, make the insn jump to itself. */
3832 if (JUMP_LABEL (insn
) == label
)
3835 tem
= next_active_insn (JUMP_LABEL (insn
));
3836 if (tem
&& (GET_CODE (PATTERN (tem
)) == ADDR_VEC
3837 || GET_CODE (PATTERN (tem
)) == ADDR_DIFF_VEC
))
3840 value
= JUMP_LABEL (insn
);
3847 /* Assuming that field IDX of X is a vector of label_refs,
3848 replace each of them by the ultimate label reached by it.
3849 Return nonzero if a change is made.
3850 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3853 tension_vector_labels (x
, idx
)
3859 for (i
= XVECLEN (x
, idx
) - 1; i
>= 0; i
--)
3861 register rtx olabel
= XEXP (XVECEXP (x
, idx
, i
), 0);
3862 register rtx nlabel
= follow_jumps (olabel
);
3863 if (nlabel
&& nlabel
!= olabel
)
3865 XEXP (XVECEXP (x
, idx
, i
), 0) = nlabel
;
3866 ++LABEL_NUSES (nlabel
);
3867 if (--LABEL_NUSES (olabel
) == 0)
3868 delete_insn (olabel
);
3875 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3876 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3877 in INSN, then store one of them in JUMP_LABEL (INSN).
3878 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3879 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3880 Also, when there are consecutive labels, canonicalize on the last of them.
3882 Note that two labels separated by a loop-beginning note
3883 must be kept distinct if we have not yet done loop-optimization,
3884 because the gap between them is where loop-optimize
3885 will want to move invariant code to. CROSS_JUMP tells us
3886 that loop-optimization is done with.
3888 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3889 two labels distinct if they are separated by only USE or CLOBBER insns. */
3892 mark_jump_label (x
, insn
, cross_jump
)
3897 register RTX_CODE code
= GET_CODE (x
);
3899 register const char *fmt
;
3915 /* If this is a constant-pool reference, see if it is a label. */
3916 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3917 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3918 mark_jump_label (get_pool_constant (XEXP (x
, 0)), insn
, cross_jump
);
3923 rtx label
= XEXP (x
, 0);
3928 if (GET_CODE (label
) != CODE_LABEL
)
3931 /* Ignore references to labels of containing functions. */
3932 if (LABEL_REF_NONLOCAL_P (x
))
3935 /* If there are other labels following this one,
3936 replace it with the last of the consecutive labels. */
3937 for (next
= NEXT_INSN (label
); next
; next
= NEXT_INSN (next
))
3939 if (GET_CODE (next
) == CODE_LABEL
)
3941 else if (cross_jump
&& GET_CODE (next
) == INSN
3942 && (GET_CODE (PATTERN (next
)) == USE
3943 || GET_CODE (PATTERN (next
)) == CLOBBER
))
3945 else if (GET_CODE (next
) != NOTE
)
3947 else if (! cross_jump
3948 && (NOTE_LINE_NUMBER (next
) == NOTE_INSN_LOOP_BEG
3949 || NOTE_LINE_NUMBER (next
) == NOTE_INSN_FUNCTION_END
3950 /* ??? Optional. Disables some optimizations, but
3951 makes gcov output more accurate with -O. */
3952 || (flag_test_coverage
&& NOTE_LINE_NUMBER (next
) > 0)))
3956 XEXP (x
, 0) = label
;
3957 if (! insn
|| ! INSN_DELETED_P (insn
))
3958 ++LABEL_NUSES (label
);
3962 if (GET_CODE (insn
) == JUMP_INSN
)
3963 JUMP_LABEL (insn
) = label
;
3965 /* If we've changed OLABEL and we had a REG_LABEL note
3966 for it, update it as well. */
3967 else if (label
!= olabel
3968 && (note
= find_reg_note (insn
, REG_LABEL
, olabel
)) != 0)
3969 XEXP (note
, 0) = label
;
3971 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3973 else if (! find_reg_note (insn
, REG_LABEL
, label
))
3975 /* This code used to ignore labels which refered to dispatch
3976 tables to avoid flow.c generating worse code.
3978 However, in the presense of global optimizations like
3979 gcse which call find_basic_blocks without calling
3980 life_analysis, not recording such labels will lead
3981 to compiler aborts because of inconsistencies in the
3982 flow graph. So we go ahead and record the label.
3984 It may also be the case that the optimization argument
3985 is no longer valid because of the more accurate cfg
3986 we build in find_basic_blocks -- it no longer pessimizes
3987 code when it finds a REG_LABEL note. */
3988 REG_NOTES (insn
) = gen_rtx_EXPR_LIST (REG_LABEL
, label
,
3995 /* Do walk the labels in a vector, but not the first operand of an
3996 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3999 if (! INSN_DELETED_P (insn
))
4001 int eltnum
= code
== ADDR_DIFF_VEC
? 1 : 0;
4003 for (i
= 0; i
< XVECLEN (x
, eltnum
); i
++)
4004 mark_jump_label (XVECEXP (x
, eltnum
, i
), NULL_RTX
, cross_jump
);
4012 fmt
= GET_RTX_FORMAT (code
);
4013 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4016 mark_jump_label (XEXP (x
, i
), insn
, cross_jump
);
4017 else if (fmt
[i
] == 'E')
4020 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4021 mark_jump_label (XVECEXP (x
, i
, j
), insn
, cross_jump
);
4026 /* If all INSN does is set the pc, delete it,
4027 and delete the insn that set the condition codes for it
4028 if that's what the previous thing was. */
4034 register rtx set
= single_set (insn
);
4036 if (set
&& GET_CODE (SET_DEST (set
)) == PC
)
4037 delete_computation (insn
);
4040 /* Recursively delete prior insns that compute the value (used only by INSN
4041 which the caller is deleting) stored in the register mentioned by NOTE
4042 which is a REG_DEAD note associated with INSN. */
4045 delete_prior_computation (note
, insn
)
4050 rtx reg
= XEXP (note
, 0);
4052 for (our_prev
= prev_nonnote_insn (insn
);
4053 our_prev
&& (GET_CODE (our_prev
) == INSN
4054 || GET_CODE (our_prev
) == CALL_INSN
);
4055 our_prev
= prev_nonnote_insn (our_prev
))
4057 rtx pat
= PATTERN (our_prev
);
4059 /* If we reach a CALL which is not calling a const function
4060 or the callee pops the arguments, then give up. */
4061 if (GET_CODE (our_prev
) == CALL_INSN
4062 && (! CONST_CALL_P (our_prev
)
4063 || GET_CODE (pat
) != SET
|| GET_CODE (SET_SRC (pat
)) != CALL
))
4066 /* If we reach a SEQUENCE, it is too complex to try to
4067 do anything with it, so give up. */
4068 if (GET_CODE (pat
) == SEQUENCE
)
4071 if (GET_CODE (pat
) == USE
4072 && GET_CODE (XEXP (pat
, 0)) == INSN
)
4073 /* reorg creates USEs that look like this. We leave them
4074 alone because reorg needs them for its own purposes. */
4077 if (reg_set_p (reg
, pat
))
4079 if (side_effects_p (pat
) && GET_CODE (our_prev
) != CALL_INSN
)
4082 if (GET_CODE (pat
) == PARALLEL
)
4084 /* If we find a SET of something else, we can't
4089 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
4091 rtx part
= XVECEXP (pat
, 0, i
);
4093 if (GET_CODE (part
) == SET
4094 && SET_DEST (part
) != reg
)
4098 if (i
== XVECLEN (pat
, 0))
4099 delete_computation (our_prev
);
4101 else if (GET_CODE (pat
) == SET
4102 && GET_CODE (SET_DEST (pat
)) == REG
)
4104 int dest_regno
= REGNO (SET_DEST (pat
));
4106 = dest_regno
+ (dest_regno
< FIRST_PSEUDO_REGISTER
4107 ? HARD_REGNO_NREGS (dest_regno
,
4108 GET_MODE (SET_DEST (pat
))) : 1);
4109 int regno
= REGNO (reg
);
4110 int endregno
= regno
+ (regno
< FIRST_PSEUDO_REGISTER
4111 ? HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) : 1);
4113 if (dest_regno
>= regno
4114 && dest_endregno
<= endregno
)
4115 delete_computation (our_prev
);
4117 /* We may have a multi-word hard register and some, but not
4118 all, of the words of the register are needed in subsequent
4119 insns. Write REG_UNUSED notes for those parts that were not
4121 else if (dest_regno
<= regno
4122 && dest_endregno
>= endregno
)
4126 REG_NOTES (our_prev
)
4127 = gen_rtx_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (our_prev
));
4129 for (i
= dest_regno
; i
< dest_endregno
; i
++)
4130 if (! find_regno_note (our_prev
, REG_UNUSED
, i
))
4133 if (i
== dest_endregno
)
4134 delete_computation (our_prev
);
4141 /* If PAT references the register that dies here, it is an
4142 additional use. Hence any prior SET isn't dead. However, this
4143 insn becomes the new place for the REG_DEAD note. */
4144 if (reg_overlap_mentioned_p (reg
, pat
))
4146 XEXP (note
, 1) = REG_NOTES (our_prev
);
4147 REG_NOTES (our_prev
) = note
;
4153 /* Delete INSN and recursively delete insns that compute values used only
4154 by INSN. This uses the REG_DEAD notes computed during flow analysis.
4155 If we are running before flow.c, we need do nothing since flow.c will
4156 delete dead code. We also can't know if the registers being used are
4157 dead or not at this point.
4159 Otherwise, look at all our REG_DEAD notes. If a previous insn does
4160 nothing other than set a register that dies in this insn, we can delete
4163 On machines with CC0, if CC0 is used in this insn, we may be able to
4164 delete the insn that set it. */
4167 delete_computation (insn
)
4174 if (reg_referenced_p (cc0_rtx
, PATTERN (insn
)))
4176 rtx prev
= prev_nonnote_insn (insn
);
4177 /* We assume that at this stage
4178 CC's are always set explicitly
4179 and always immediately before the jump that
4180 will use them. So if the previous insn
4181 exists to set the CC's, delete it
4182 (unless it performs auto-increments, etc.). */
4183 if (prev
&& GET_CODE (prev
) == INSN
4184 && sets_cc0_p (PATTERN (prev
)))
4186 if (sets_cc0_p (PATTERN (prev
)) > 0
4187 && ! side_effects_p (PATTERN (prev
)))
4188 delete_computation (prev
);
4190 /* Otherwise, show that cc0 won't be used. */
4191 REG_NOTES (prev
) = gen_rtx_EXPR_LIST (REG_UNUSED
,
4192 cc0_rtx
, REG_NOTES (prev
));
4197 #ifdef INSN_SCHEDULING
4198 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
4199 reload has completed. The schedulers need to be fixed. Until
4200 they are, we must not rely on the death notes here. */
4201 if (reload_completed
&& flag_schedule_insns_after_reload
)
4208 /* The REG_DEAD note may have been omitted for a register
4209 which is both set and used by the insn. */
4210 set
= single_set (insn
);
4211 if (set
&& GET_CODE (SET_DEST (set
)) == REG
)
4213 int dest_regno
= REGNO (SET_DEST (set
));
4215 = dest_regno
+ (dest_regno
< FIRST_PSEUDO_REGISTER
4216 ? HARD_REGNO_NREGS (dest_regno
,
4217 GET_MODE (SET_DEST (set
))) : 1);
4220 for (i
= dest_regno
; i
< dest_endregno
; i
++)
4222 if (! refers_to_regno_p (i
, i
+ 1, SET_SRC (set
), NULL_PTR
)
4223 || find_regno_note (insn
, REG_DEAD
, i
))
4226 note
= gen_rtx_EXPR_LIST (REG_DEAD
, (i
< FIRST_PSEUDO_REGISTER
4227 ? gen_rtx_REG (reg_raw_mode
[i
], i
)
4228 : SET_DEST (set
)), NULL_RTX
);
4229 delete_prior_computation (note
, insn
);
4233 for (note
= REG_NOTES (insn
); note
; note
= next
)
4235 next
= XEXP (note
, 1);
4237 if (REG_NOTE_KIND (note
) != REG_DEAD
4238 /* Verify that the REG_NOTE is legitimate. */
4239 || GET_CODE (XEXP (note
, 0)) != REG
)
4242 delete_prior_computation (note
, insn
);
4248 /* Delete insn INSN from the chain of insns and update label ref counts.
4249 May delete some following insns as a consequence; may even delete
4250 a label elsewhere and insns that follow it.
4252 Returns the first insn after INSN that was not deleted. */
4258 register rtx next
= NEXT_INSN (insn
);
4259 register rtx prev
= PREV_INSN (insn
);
4260 register int was_code_label
= (GET_CODE (insn
) == CODE_LABEL
);
4261 register int dont_really_delete
= 0;
4263 while (next
&& INSN_DELETED_P (next
))
4264 next
= NEXT_INSN (next
);
4266 /* This insn is already deleted => return first following nondeleted. */
4267 if (INSN_DELETED_P (insn
))
4271 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
4273 /* Don't delete user-declared labels. Convert them to special NOTEs
4275 if (was_code_label
&& LABEL_NAME (insn
) != 0
4276 && optimize
&& ! dont_really_delete
)
4278 PUT_CODE (insn
, NOTE
);
4279 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED_LABEL
;
4280 NOTE_SOURCE_FILE (insn
) = 0;
4281 dont_really_delete
= 1;
4284 /* Mark this insn as deleted. */
4285 INSN_DELETED_P (insn
) = 1;
4287 /* If this is an unconditional jump, delete it from the jump chain. */
4288 if (simplejump_p (insn
))
4289 delete_from_jump_chain (insn
);
4291 /* If instruction is followed by a barrier,
4292 delete the barrier too. */
4294 if (next
!= 0 && GET_CODE (next
) == BARRIER
)
4296 INSN_DELETED_P (next
) = 1;
4297 next
= NEXT_INSN (next
);
4300 /* Patch out INSN (and the barrier if any) */
4302 if (optimize
&& ! dont_really_delete
)
4306 NEXT_INSN (prev
) = next
;
4307 if (GET_CODE (prev
) == INSN
&& GET_CODE (PATTERN (prev
)) == SEQUENCE
)
4308 NEXT_INSN (XVECEXP (PATTERN (prev
), 0,
4309 XVECLEN (PATTERN (prev
), 0) - 1)) = next
;
4314 PREV_INSN (next
) = prev
;
4315 if (GET_CODE (next
) == INSN
&& GET_CODE (PATTERN (next
)) == SEQUENCE
)
4316 PREV_INSN (XVECEXP (PATTERN (next
), 0, 0)) = prev
;
4319 if (prev
&& NEXT_INSN (prev
) == 0)
4320 set_last_insn (prev
);
4323 /* If deleting a jump, decrement the count of the label,
4324 and delete the label if it is now unused. */
4326 if (GET_CODE (insn
) == JUMP_INSN
&& JUMP_LABEL (insn
))
4328 rtx lab
= JUMP_LABEL (insn
), lab_next
;
4330 if (--LABEL_NUSES (lab
) == 0)
4332 /* This can delete NEXT or PREV,
4333 either directly if NEXT is JUMP_LABEL (INSN),
4334 or indirectly through more levels of jumps. */
4337 /* I feel a little doubtful about this loop,
4338 but I see no clean and sure alternative way
4339 to find the first insn after INSN that is not now deleted.
4340 I hope this works. */
4341 while (next
&& INSN_DELETED_P (next
))
4342 next
= NEXT_INSN (next
);
4345 else if ((lab_next
= next_nonnote_insn (lab
)) != NULL
4346 && GET_CODE (lab_next
) == JUMP_INSN
4347 && (GET_CODE (PATTERN (lab_next
)) == ADDR_VEC
4348 || GET_CODE (PATTERN (lab_next
)) == ADDR_DIFF_VEC
))
4350 /* If we're deleting the tablejump, delete the dispatch table.
4351 We may not be able to kill the label immediately preceeding
4352 just yet, as it might be referenced in code leading up to
4354 delete_insn (lab_next
);
4358 /* Likewise if we're deleting a dispatch table. */
4360 if (GET_CODE (insn
) == JUMP_INSN
4361 && (GET_CODE (PATTERN (insn
)) == ADDR_VEC
4362 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
))
4364 rtx pat
= PATTERN (insn
);
4365 int i
, diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
4366 int len
= XVECLEN (pat
, diff_vec_p
);
4368 for (i
= 0; i
< len
; i
++)
4369 if (--LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0)) == 0)
4370 delete_insn (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0));
4371 while (next
&& INSN_DELETED_P (next
))
4372 next
= NEXT_INSN (next
);
4376 while (prev
&& (INSN_DELETED_P (prev
) || GET_CODE (prev
) == NOTE
))
4377 prev
= PREV_INSN (prev
);
4379 /* If INSN was a label and a dispatch table follows it,
4380 delete the dispatch table. The tablejump must have gone already.
4381 It isn't useful to fall through into a table. */
4384 && NEXT_INSN (insn
) != 0
4385 && GET_CODE (NEXT_INSN (insn
)) == JUMP_INSN
4386 && (GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_VEC
4387 || GET_CODE (PATTERN (NEXT_INSN (insn
))) == ADDR_DIFF_VEC
))
4388 next
= delete_insn (NEXT_INSN (insn
));
4390 /* If INSN was a label, delete insns following it if now unreachable. */
4392 if (was_code_label
&& prev
&& GET_CODE (prev
) == BARRIER
)
4394 register RTX_CODE code
;
4396 && (GET_RTX_CLASS (code
= GET_CODE (next
)) == 'i'
4397 || code
== NOTE
|| code
== BARRIER
4398 || (code
== CODE_LABEL
&& INSN_DELETED_P (next
))))
4401 && NOTE_LINE_NUMBER (next
) != NOTE_INSN_FUNCTION_END
)
4402 next
= NEXT_INSN (next
);
4403 /* Keep going past other deleted labels to delete what follows. */
4404 else if (code
== CODE_LABEL
&& INSN_DELETED_P (next
))
4405 next
= NEXT_INSN (next
);
4407 /* Note: if this deletes a jump, it can cause more
4408 deletion of unreachable code, after a different label.
4409 As long as the value from this recursive call is correct,
4410 this invocation functions correctly. */
4411 next
= delete_insn (next
);
4418 /* Advance from INSN till reaching something not deleted
4419 then return that. May return INSN itself. */
4422 next_nondeleted_insn (insn
)
4425 while (INSN_DELETED_P (insn
))
4426 insn
= NEXT_INSN (insn
);
4430 /* Delete a range of insns from FROM to TO, inclusive.
4431 This is for the sake of peephole optimization, so assume
4432 that whatever these insns do will still be done by a new
4433 peephole insn that will replace them. */
4436 delete_for_peephole (from
, to
)
4437 register rtx from
, to
;
4439 register rtx insn
= from
;
4443 register rtx next
= NEXT_INSN (insn
);
4444 register rtx prev
= PREV_INSN (insn
);
4446 if (GET_CODE (insn
) != NOTE
)
4448 INSN_DELETED_P (insn
) = 1;
4450 /* Patch this insn out of the chain. */
4451 /* We don't do this all at once, because we
4452 must preserve all NOTEs. */
4454 NEXT_INSN (prev
) = next
;
4457 PREV_INSN (next
) = prev
;
4465 /* Note that if TO is an unconditional jump
4466 we *do not* delete the BARRIER that follows,
4467 since the peephole that replaces this sequence
4468 is also an unconditional jump in that case. */
4471 /* We have determined that INSN is never reached, and are about to
4472 delete it. Print a warning if the user asked for one.
4474 To try to make this warning more useful, this should only be called
4475 once per basic block not reached, and it only warns when the basic
4476 block contains more than one line from the current function, and
4477 contains at least one operation. CSE and inlining can duplicate insns,
4478 so it's possible to get spurious warnings from this. */
4481 never_reached_warning (avoided_insn
)
4485 rtx a_line_note
= NULL
;
4486 int two_avoided_lines
= 0;
4487 int contains_insn
= 0;
4489 if (! warn_notreached
)
4492 /* Scan forwards, looking at LINE_NUMBER notes, until
4493 we hit a LABEL or we run out of insns. */
4495 for (insn
= avoided_insn
; insn
!= NULL
; insn
= NEXT_INSN (insn
))
4497 if (GET_CODE (insn
) == CODE_LABEL
)
4499 else if (GET_CODE (insn
) == NOTE
/* A line number note? */
4500 && NOTE_LINE_NUMBER (insn
) >= 0)
4502 if (a_line_note
== NULL
)
4505 two_avoided_lines
|= (NOTE_LINE_NUMBER (a_line_note
)
4506 != NOTE_LINE_NUMBER (insn
));
4508 else if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
4511 if (two_avoided_lines
&& contains_insn
)
4512 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note
),
4513 NOTE_LINE_NUMBER (a_line_note
),
4514 "will never be executed");
4517 /* Invert the condition of the jump JUMP, and make it jump
4518 to label NLABEL instead of where it jumps now. */
4521 invert_jump (jump
, nlabel
)
4524 /* We have to either invert the condition and change the label or
4525 do neither. Either operation could fail. We first try to invert
4526 the jump. If that succeeds, we try changing the label. If that fails,
4527 we invert the jump back to what it was. */
4529 if (! invert_exp (PATTERN (jump
), jump
))
4532 if (redirect_jump (jump
, nlabel
))
4534 if (flag_branch_probabilities
)
4536 rtx note
= find_reg_note (jump
, REG_BR_PROB
, 0);
4538 /* An inverted jump means that a probability taken becomes a
4539 probability not taken. Subtract the branch probability from the
4540 probability base to convert it back to a taken probability.
4541 (We don't flip the probability on a branch that's never taken. */
4542 if (note
&& XINT (XEXP (note
, 0), 0) >= 0)
4543 XINT (XEXP (note
, 0), 0) = REG_BR_PROB_BASE
- XINT (XEXP (note
, 0), 0);
4549 if (! invert_exp (PATTERN (jump
), jump
))
4550 /* This should just be putting it back the way it was. */
4556 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4558 Return 1 if we can do so, 0 if we cannot find a way to do so that
4559 matches a pattern. */
4562 invert_exp (x
, insn
)
4566 register RTX_CODE code
;
4568 register const char *fmt
;
4570 code
= GET_CODE (x
);
4572 if (code
== IF_THEN_ELSE
)
4574 register rtx comp
= XEXP (x
, 0);
4577 /* We can do this in two ways: The preferable way, which can only
4578 be done if this is not an integer comparison, is to reverse
4579 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4580 of the IF_THEN_ELSE. If we can't do either, fail. */
4582 if (can_reverse_comparison_p (comp
, insn
)
4583 && validate_change (insn
, &XEXP (x
, 0),
4584 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp
)),
4585 GET_MODE (comp
), XEXP (comp
, 0),
4586 XEXP (comp
, 1)), 0))
4590 validate_change (insn
, &XEXP (x
, 1), XEXP (x
, 2), 1);
4591 validate_change (insn
, &XEXP (x
, 2), tem
, 1);
4592 return apply_change_group ();
4595 fmt
= GET_RTX_FORMAT (code
);
4596 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4599 if (! invert_exp (XEXP (x
, i
), insn
))
4604 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4605 if (!invert_exp (XVECEXP (x
, i
, j
), insn
))
4613 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4614 If the old jump target label is unused as a result,
4615 it and the code following it may be deleted.
4617 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4620 The return value will be 1 if the change was made, 0 if it wasn't (this
4621 can only occur for NLABEL == 0). */
4624 redirect_jump (jump
, nlabel
)
4627 register rtx olabel
= JUMP_LABEL (jump
);
4629 if (nlabel
== olabel
)
4632 if (! redirect_exp (&PATTERN (jump
), olabel
, nlabel
, jump
))
4635 /* If this is an unconditional branch, delete it from the jump_chain of
4636 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4637 have UID's in range and JUMP_CHAIN is valid). */
4638 if (jump_chain
&& (simplejump_p (jump
)
4639 || GET_CODE (PATTERN (jump
)) == RETURN
))
4641 int label_index
= nlabel
? INSN_UID (nlabel
) : 0;
4643 delete_from_jump_chain (jump
);
4644 if (label_index
< max_jump_chain
4645 && INSN_UID (jump
) < max_jump_chain
)
4647 jump_chain
[INSN_UID (jump
)] = jump_chain
[label_index
];
4648 jump_chain
[label_index
] = jump
;
4652 JUMP_LABEL (jump
) = nlabel
;
4654 ++LABEL_NUSES (nlabel
);
4656 if (olabel
&& --LABEL_NUSES (olabel
) == 0)
4657 delete_insn (olabel
);
4662 /* Delete the instruction JUMP from any jump chain it might be on. */
4665 delete_from_jump_chain (jump
)
4669 rtx olabel
= JUMP_LABEL (jump
);
4671 /* Handle unconditional jumps. */
4672 if (jump_chain
&& olabel
!= 0
4673 && INSN_UID (olabel
) < max_jump_chain
4674 && simplejump_p (jump
))
4675 index
= INSN_UID (olabel
);
4676 /* Handle return insns. */
4677 else if (jump_chain
&& GET_CODE (PATTERN (jump
)) == RETURN
)
4681 if (jump_chain
[index
] == jump
)
4682 jump_chain
[index
] = jump_chain
[INSN_UID (jump
)];
4687 for (insn
= jump_chain
[index
];
4689 insn
= jump_chain
[INSN_UID (insn
)])
4690 if (jump_chain
[INSN_UID (insn
)] == jump
)
4692 jump_chain
[INSN_UID (insn
)] = jump_chain
[INSN_UID (jump
)];
4698 /* If NLABEL is nonzero, throughout the rtx at LOC,
4699 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4700 zero, alter (RETURN) to (LABEL_REF NLABEL).
4702 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4703 validity with validate_change. Convert (set (pc) (label_ref olabel))
4706 Return 0 if we found a change we would like to make but it is invalid.
4707 Otherwise, return 1. */
4710 redirect_exp (loc
, olabel
, nlabel
, insn
)
4715 register rtx x
= *loc
;
4716 register RTX_CODE code
= GET_CODE (x
);
4718 register const char *fmt
;
4720 if (code
== LABEL_REF
)
4722 if (XEXP (x
, 0) == olabel
)
4725 XEXP (x
, 0) = nlabel
;
4727 return validate_change (insn
, loc
, gen_rtx_RETURN (VOIDmode
), 0);
4731 else if (code
== RETURN
&& olabel
== 0)
4733 x
= gen_rtx_LABEL_REF (VOIDmode
, nlabel
);
4734 if (loc
== &PATTERN (insn
))
4735 x
= gen_rtx_SET (VOIDmode
, pc_rtx
, x
);
4736 return validate_change (insn
, loc
, x
, 0);
4739 if (code
== SET
&& nlabel
== 0 && SET_DEST (x
) == pc_rtx
4740 && GET_CODE (SET_SRC (x
)) == LABEL_REF
4741 && XEXP (SET_SRC (x
), 0) == olabel
)
4742 return validate_change (insn
, loc
, gen_rtx_RETURN (VOIDmode
), 0);
4744 fmt
= GET_RTX_FORMAT (code
);
4745 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4748 if (! redirect_exp (&XEXP (x
, i
), olabel
, nlabel
, insn
))
4753 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4754 if (! redirect_exp (&XVECEXP (x
, i
, j
), olabel
, nlabel
, insn
))
4762 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4764 If the old jump target label (before the dispatch table) becomes unused,
4765 it and the dispatch table may be deleted. In that case, find the insn
4766 before the jump references that label and delete it and logical successors
4770 redirect_tablejump (jump
, nlabel
)
4773 register rtx olabel
= JUMP_LABEL (jump
);
4775 /* Add this jump to the jump_chain of NLABEL. */
4776 if (jump_chain
&& INSN_UID (nlabel
) < max_jump_chain
4777 && INSN_UID (jump
) < max_jump_chain
)
4779 jump_chain
[INSN_UID (jump
)] = jump_chain
[INSN_UID (nlabel
)];
4780 jump_chain
[INSN_UID (nlabel
)] = jump
;
4783 PATTERN (jump
) = gen_jump (nlabel
);
4784 JUMP_LABEL (jump
) = nlabel
;
4785 ++LABEL_NUSES (nlabel
);
4786 INSN_CODE (jump
) = -1;
4788 if (--LABEL_NUSES (olabel
) == 0)
4790 delete_labelref_insn (jump
, olabel
, 0);
4791 delete_insn (olabel
);
4795 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4796 If we found one, delete it and then delete this insn if DELETE_THIS is
4797 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4800 delete_labelref_insn (insn
, label
, delete_this
)
4807 if (GET_CODE (insn
) != NOTE
4808 && reg_mentioned_p (label
, PATTERN (insn
)))
4819 for (link
= LOG_LINKS (insn
); link
; link
= XEXP (link
, 1))
4820 if (delete_labelref_insn (XEXP (link
, 0), label
, 1))
4834 /* Like rtx_equal_p except that it considers two REGs as equal
4835 if they renumber to the same value and considers two commutative
4836 operations to be the same if the order of the operands has been
4839 ??? Addition is not commutative on the PA due to the weird implicit
4840 space register selection rules for memory addresses. Therefore, we
4841 don't consider a + b == b + a.
4843 We could/should make this test a little tighter. Possibly only
4844 disabling it on the PA via some backend macro or only disabling this
4845 case when the PLUS is inside a MEM. */
4848 rtx_renumbered_equal_p (x
, y
)
4852 register RTX_CODE code
= GET_CODE (x
);
4853 register const char *fmt
;
4858 if ((code
== REG
|| (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
))
4859 && (GET_CODE (y
) == REG
|| (GET_CODE (y
) == SUBREG
4860 && GET_CODE (SUBREG_REG (y
)) == REG
)))
4862 int reg_x
= -1, reg_y
= -1;
4863 int word_x
= 0, word_y
= 0;
4865 if (GET_MODE (x
) != GET_MODE (y
))
4868 /* If we haven't done any renumbering, don't
4869 make any assumptions. */
4870 if (reg_renumber
== 0)
4871 return rtx_equal_p (x
, y
);
4875 reg_x
= REGNO (SUBREG_REG (x
));
4876 word_x
= SUBREG_WORD (x
);
4878 if (reg_renumber
[reg_x
] >= 0)
4880 reg_x
= reg_renumber
[reg_x
] + word_x
;
4888 if (reg_renumber
[reg_x
] >= 0)
4889 reg_x
= reg_renumber
[reg_x
];
4892 if (GET_CODE (y
) == SUBREG
)
4894 reg_y
= REGNO (SUBREG_REG (y
));
4895 word_y
= SUBREG_WORD (y
);
4897 if (reg_renumber
[reg_y
] >= 0)
4899 reg_y
= reg_renumber
[reg_y
];
4907 if (reg_renumber
[reg_y
] >= 0)
4908 reg_y
= reg_renumber
[reg_y
];
4911 return reg_x
>= 0 && reg_x
== reg_y
&& word_x
== word_y
;
4914 /* Now we have disposed of all the cases
4915 in which different rtx codes can match. */
4916 if (code
!= GET_CODE (y
))
4928 return INTVAL (x
) == INTVAL (y
);
4931 /* We can't assume nonlocal labels have their following insns yet. */
4932 if (LABEL_REF_NONLOCAL_P (x
) || LABEL_REF_NONLOCAL_P (y
))
4933 return XEXP (x
, 0) == XEXP (y
, 0);
4935 /* Two label-refs are equivalent if they point at labels
4936 in the same position in the instruction stream. */
4937 return (next_real_insn (XEXP (x
, 0))
4938 == next_real_insn (XEXP (y
, 0)));
4941 return XSTR (x
, 0) == XSTR (y
, 0);
4944 /* If we didn't match EQ equality above, they aren't the same. */
4951 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4953 if (GET_MODE (x
) != GET_MODE (y
))
4956 /* For commutative operations, the RTX match if the operand match in any
4957 order. Also handle the simple binary and unary cases without a loop.
4959 ??? Don't consider PLUS a commutative operator; see comments above. */
4960 if ((code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
4962 return ((rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
4963 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)))
4964 || (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 1))
4965 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 0))));
4966 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
4967 return (rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0))
4968 && rtx_renumbered_equal_p (XEXP (x
, 1), XEXP (y
, 1)));
4969 else if (GET_RTX_CLASS (code
) == '1')
4970 return rtx_renumbered_equal_p (XEXP (x
, 0), XEXP (y
, 0));
4972 /* Compare the elements. If any pair of corresponding elements
4973 fail to match, return 0 for the whole things. */
4975 fmt
= GET_RTX_FORMAT (code
);
4976 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4982 if (XWINT (x
, i
) != XWINT (y
, i
))
4987 if (XINT (x
, i
) != XINT (y
, i
))
4992 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
4997 if (! rtx_renumbered_equal_p (XEXP (x
, i
), XEXP (y
, i
)))
5002 if (XEXP (x
, i
) != XEXP (y
, i
))
5009 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
5011 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5012 if (!rtx_renumbered_equal_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
5023 /* If X is a hard register or equivalent to one or a subregister of one,
5024 return the hard register number. If X is a pseudo register that was not
5025 assigned a hard register, return the pseudo register number. Otherwise,
5026 return -1. Any rtx is valid for X. */
5032 if (GET_CODE (x
) == REG
)
5034 if (REGNO (x
) >= FIRST_PSEUDO_REGISTER
&& reg_renumber
[REGNO (x
)] >= 0)
5035 return reg_renumber
[REGNO (x
)];
5038 if (GET_CODE (x
) == SUBREG
)
5040 int base
= true_regnum (SUBREG_REG (x
));
5041 if (base
>= 0 && base
< FIRST_PSEUDO_REGISTER
)
5042 return SUBREG_WORD (x
) + base
;
5047 /* Optimize code of the form:
5049 for (x = a[i]; x; ...)
5051 for (x = a[i]; x; ...)
5055 Loop optimize will change the above code into
5059 { ...; if (! (x = ...)) break; }
5062 { ...; if (! (x = ...)) break; }
5065 In general, if the first test fails, the program can branch
5066 directly to `foo' and skip the second try which is doomed to fail.
5067 We run this after loop optimization and before flow analysis. */
5069 /* When comparing the insn patterns, we track the fact that different
5070 pseudo-register numbers may have been used in each computation.
5071 The following array stores an equivalence -- same_regs[I] == J means
5072 that pseudo register I was used in the first set of tests in a context
5073 where J was used in the second set. We also count the number of such
5074 pending equivalences. If nonzero, the expressions really aren't the
5077 static int *same_regs
;
5079 static int num_same_regs
;
5081 /* Track any registers modified between the target of the first jump and
5082 the second jump. They never compare equal. */
5084 static char *modified_regs
;
5086 /* Record if memory was modified. */
5088 static int modified_mem
;
5090 /* Called via note_stores on each insn between the target of the first
5091 branch and the second branch. It marks any changed registers. */
5094 mark_modified_reg (dest
, x
)
5096 rtx x ATTRIBUTE_UNUSED
;
5100 if (GET_CODE (dest
) == SUBREG
)
5101 dest
= SUBREG_REG (dest
);
5103 if (GET_CODE (dest
) == MEM
)
5106 if (GET_CODE (dest
) != REG
)
5109 regno
= REGNO (dest
);
5110 if (regno
>= FIRST_PSEUDO_REGISTER
)
5111 modified_regs
[regno
] = 1;
5113 for (i
= 0; i
< HARD_REGNO_NREGS (regno
, GET_MODE (dest
)); i
++)
5114 modified_regs
[regno
+ i
] = 1;
5117 /* F is the first insn in the chain of insns. */
5120 thread_jumps (f
, max_reg
, flag_before_loop
)
5123 int flag_before_loop
;
5125 /* Basic algorithm is to find a conditional branch,
5126 the label it may branch to, and the branch after
5127 that label. If the two branches test the same condition,
5128 walk back from both branch paths until the insn patterns
5129 differ, or code labels are hit. If we make it back to
5130 the target of the first branch, then we know that the first branch
5131 will either always succeed or always fail depending on the relative
5132 senses of the two branches. So adjust the first branch accordingly
5135 rtx label
, b1
, b2
, t1
, t2
;
5136 enum rtx_code code1
, code2
;
5137 rtx b1op0
, b1op1
, b2op0
, b2op1
;
5142 /* Allocate register tables and quick-reset table. */
5143 modified_regs
= (char *) alloca (max_reg
* sizeof (char));
5144 same_regs
= (int *) alloca (max_reg
* sizeof (int));
5145 all_reset
= (int *) alloca (max_reg
* sizeof (int));
5146 for (i
= 0; i
< max_reg
; i
++)
5153 for (b1
= f
; b1
; b1
= NEXT_INSN (b1
))
5155 /* Get to a candidate branch insn. */
5156 if (GET_CODE (b1
) != JUMP_INSN
5157 || ! condjump_p (b1
) || simplejump_p (b1
)
5158 || JUMP_LABEL (b1
) == 0)
5161 bzero (modified_regs
, max_reg
* sizeof (char));
5164 bcopy ((char *) all_reset
, (char *) same_regs
,
5165 max_reg
* sizeof (int));
5168 label
= JUMP_LABEL (b1
);
5170 /* Look for a branch after the target. Record any registers and
5171 memory modified between the target and the branch. Stop when we
5172 get to a label since we can't know what was changed there. */
5173 for (b2
= NEXT_INSN (label
); b2
; b2
= NEXT_INSN (b2
))
5175 if (GET_CODE (b2
) == CODE_LABEL
)
5178 else if (GET_CODE (b2
) == JUMP_INSN
)
5180 /* If this is an unconditional jump and is the only use of
5181 its target label, we can follow it. */
5182 if (simplejump_p (b2
)
5183 && JUMP_LABEL (b2
) != 0
5184 && LABEL_NUSES (JUMP_LABEL (b2
)) == 1)
5186 b2
= JUMP_LABEL (b2
);
5193 if (GET_CODE (b2
) != CALL_INSN
&& GET_CODE (b2
) != INSN
)
5196 if (GET_CODE (b2
) == CALL_INSN
)
5199 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
5200 if (call_used_regs
[i
] && ! fixed_regs
[i
]
5201 && i
!= STACK_POINTER_REGNUM
5202 && i
!= FRAME_POINTER_REGNUM
5203 && i
!= HARD_FRAME_POINTER_REGNUM
5204 && i
!= ARG_POINTER_REGNUM
)
5205 modified_regs
[i
] = 1;
5208 note_stores (PATTERN (b2
), mark_modified_reg
);
5211 /* Check the next candidate branch insn from the label
5214 || GET_CODE (b2
) != JUMP_INSN
5216 || ! condjump_p (b2
)
5217 || simplejump_p (b2
))
5220 /* Get the comparison codes and operands, reversing the
5221 codes if appropriate. If we don't have comparison codes,
5222 we can't do anything. */
5223 b1op0
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 0);
5224 b1op1
= XEXP (XEXP (SET_SRC (PATTERN (b1
)), 0), 1);
5225 code1
= GET_CODE (XEXP (SET_SRC (PATTERN (b1
)), 0));
5226 if (XEXP (SET_SRC (PATTERN (b1
)), 1) == pc_rtx
)
5227 code1
= reverse_condition (code1
);
5229 b2op0
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 0);
5230 b2op1
= XEXP (XEXP (SET_SRC (PATTERN (b2
)), 0), 1);
5231 code2
= GET_CODE (XEXP (SET_SRC (PATTERN (b2
)), 0));
5232 if (XEXP (SET_SRC (PATTERN (b2
)), 1) == pc_rtx
)
5233 code2
= reverse_condition (code2
);
5235 /* If they test the same things and knowing that B1 branches
5236 tells us whether or not B2 branches, check if we
5237 can thread the branch. */
5238 if (rtx_equal_for_thread_p (b1op0
, b2op0
, b2
)
5239 && rtx_equal_for_thread_p (b1op1
, b2op1
, b2
)
5240 && (comparison_dominates_p (code1
, code2
)
5241 || (comparison_dominates_p (code1
, reverse_condition (code2
))
5242 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1
)),
5246 t1
= prev_nonnote_insn (b1
);
5247 t2
= prev_nonnote_insn (b2
);
5249 while (t1
!= 0 && t2
!= 0)
5253 /* We have reached the target of the first branch.
5254 If there are no pending register equivalents,
5255 we know that this branch will either always
5256 succeed (if the senses of the two branches are
5257 the same) or always fail (if not). */
5260 if (num_same_regs
!= 0)
5263 if (comparison_dominates_p (code1
, code2
))
5264 new_label
= JUMP_LABEL (b2
);
5266 new_label
= get_label_after (b2
);
5268 if (JUMP_LABEL (b1
) != new_label
)
5270 rtx prev
= PREV_INSN (new_label
);
5272 if (flag_before_loop
5273 && GET_CODE (prev
) == NOTE
5274 && NOTE_LINE_NUMBER (prev
) == NOTE_INSN_LOOP_BEG
)
5276 /* Don't thread to the loop label. If a loop
5277 label is reused, loop optimization will
5278 be disabled for that loop. */
5279 new_label
= gen_label_rtx ();
5280 emit_label_after (new_label
, PREV_INSN (prev
));
5282 changed
|= redirect_jump (b1
, new_label
);
5287 /* If either of these is not a normal insn (it might be
5288 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
5289 have already been skipped above.) Similarly, fail
5290 if the insns are different. */
5291 if (GET_CODE (t1
) != INSN
|| GET_CODE (t2
) != INSN
5292 || recog_memoized (t1
) != recog_memoized (t2
)
5293 || ! rtx_equal_for_thread_p (PATTERN (t1
),
5297 t1
= prev_nonnote_insn (t1
);
5298 t2
= prev_nonnote_insn (t2
);
5305 /* This is like RTX_EQUAL_P except that it knows about our handling of
5306 possibly equivalent registers and knows to consider volatile and
5307 modified objects as not equal.
5309 YINSN is the insn containing Y. */
5312 rtx_equal_for_thread_p (x
, y
, yinsn
)
5318 register enum rtx_code code
;
5319 register const char *fmt
;
5321 code
= GET_CODE (x
);
5322 /* Rtx's of different codes cannot be equal. */
5323 if (code
!= GET_CODE (y
))
5326 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
5327 (REG:SI x) and (REG:HI x) are NOT equivalent. */
5329 if (GET_MODE (x
) != GET_MODE (y
))
5332 /* For floating-point, consider everything unequal. This is a bit
5333 pessimistic, but this pass would only rarely do anything for FP
5335 if (TARGET_FLOAT_FORMAT
== IEEE_FLOAT_FORMAT
5336 && FLOAT_MODE_P (GET_MODE (x
)) && ! flag_fast_math
)
5339 /* For commutative operations, the RTX match if the operand match in any
5340 order. Also handle the simple binary and unary cases without a loop. */
5341 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
5342 return ((rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
5343 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
))
5344 || (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 1), yinsn
)
5345 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 0), yinsn
)));
5346 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
5347 return (rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
)
5348 && rtx_equal_for_thread_p (XEXP (x
, 1), XEXP (y
, 1), yinsn
));
5349 else if (GET_RTX_CLASS (code
) == '1')
5350 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
5352 /* Handle special-cases first. */
5356 if (REGNO (x
) == REGNO (y
) && ! modified_regs
[REGNO (x
)])
5359 /* If neither is user variable or hard register, check for possible
5361 if (REG_USERVAR_P (x
) || REG_USERVAR_P (y
)
5362 || REGNO (x
) < FIRST_PSEUDO_REGISTER
5363 || REGNO (y
) < FIRST_PSEUDO_REGISTER
)
5366 if (same_regs
[REGNO (x
)] == -1)
5368 same_regs
[REGNO (x
)] = REGNO (y
);
5371 /* If this is the first time we are seeing a register on the `Y'
5372 side, see if it is the last use. If not, we can't thread the
5373 jump, so mark it as not equivalent. */
5374 if (REGNO_LAST_UID (REGNO (y
)) != INSN_UID (yinsn
))
5380 return (same_regs
[REGNO (x
)] == REGNO (y
));
5385 /* If memory modified or either volatile, not equivalent.
5386 Else, check address. */
5387 if (modified_mem
|| MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
5390 return rtx_equal_for_thread_p (XEXP (x
, 0), XEXP (y
, 0), yinsn
);
5393 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
5399 /* Cancel a pending `same_regs' if setting equivalenced registers.
5400 Then process source. */
5401 if (GET_CODE (SET_DEST (x
)) == REG
5402 && GET_CODE (SET_DEST (y
)) == REG
)
5404 if (same_regs
[REGNO (SET_DEST (x
))] == REGNO (SET_DEST (y
)))
5406 same_regs
[REGNO (SET_DEST (x
))] = -1;
5409 else if (REGNO (SET_DEST (x
)) != REGNO (SET_DEST (y
)))
5413 if (rtx_equal_for_thread_p (SET_DEST (x
), SET_DEST (y
), yinsn
) == 0)
5416 return rtx_equal_for_thread_p (SET_SRC (x
), SET_SRC (y
), yinsn
);
5419 return XEXP (x
, 0) == XEXP (y
, 0);
5422 return XSTR (x
, 0) == XSTR (y
, 0);
5431 fmt
= GET_RTX_FORMAT (code
);
5432 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
5437 if (XWINT (x
, i
) != XWINT (y
, i
))
5443 if (XINT (x
, i
) != XINT (y
, i
))
5449 /* Two vectors must have the same length. */
5450 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
5453 /* And the corresponding elements must match. */
5454 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5455 if (rtx_equal_for_thread_p (XVECEXP (x
, i
, j
),
5456 XVECEXP (y
, i
, j
), yinsn
) == 0)
5461 if (rtx_equal_for_thread_p (XEXP (x
, i
), XEXP (y
, i
), yinsn
) == 0)
5467 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
5472 /* These are just backpointers, so they don't matter. */
5479 /* It is believed that rtx's at this level will never
5480 contain anything but integers and other rtx's,
5481 except for within LABEL_REFs and SYMBOL_REFs. */
5490 #if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
5491 /* Return the insn that NEW can be safely inserted in front of starting at
5492 the jump insn INSN. Return 0 if it is not safe to do this jump
5493 optimization. Note that NEW must contain a single set. */
5496 find_insert_position (insn
, new)
5503 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
5504 if (GET_CODE (PATTERN (new)) != PARALLEL
)
5507 for (i
= XVECLEN (PATTERN (new), 0) - 1; i
>= 0; i
--)
5508 if (GET_CODE (XVECEXP (PATTERN (new), 0, i
)) == CLOBBER
5509 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
5516 /* There is a good chance that the previous insn PREV sets the thing
5517 being clobbered (often the CC in a hard reg). If PREV does not
5518 use what NEW sets, we can insert NEW before PREV. */
5520 prev
= prev_active_insn (insn
);
5521 for (i
= XVECLEN (PATTERN (new), 0) - 1; i
>= 0; i
--)
5522 if (GET_CODE (XVECEXP (PATTERN (new), 0, i
)) == CLOBBER
5523 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
5525 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i
), 0),
5529 return reg_mentioned_p (SET_DEST (single_set (new)), prev
) ? 0 : prev
;
5531 #endif /* !HAVE_cc0 */