1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997
3 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 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 /* Indicates whether death notes are significant in cross jump analysis.
99 Normally they are not significant, because of A and B jump to C,
100 and R dies in A, it must die in B. But this might not be true after
101 stack register conversion, and we must compare death notes in that
104 static int cross_jump_death_matters = 0;
106 static int init_label_info PARAMS ((rtx));
107 static void delete_barrier_successors PARAMS ((rtx));
108 static void mark_all_labels PARAMS ((rtx, int));
109 static rtx delete_unreferenced_labels PARAMS ((rtx));
110 static void delete_noop_moves PARAMS ((rtx));
111 static int duplicate_loop_exit_test PARAMS ((rtx));
112 static void find_cross_jump PARAMS ((rtx, rtx, int, rtx *, rtx *));
113 static void do_cross_jump PARAMS ((rtx, rtx, rtx));
114 static int jump_back_p PARAMS ((rtx, rtx));
115 static int tension_vector_labels PARAMS ((rtx, int));
116 static void delete_computation PARAMS ((rtx));
117 static void redirect_exp_1 PARAMS ((rtx *, rtx, rtx, rtx));
118 static int redirect_exp PARAMS ((rtx, rtx, rtx));
119 static void invert_exp_1 PARAMS ((rtx));
120 static int invert_exp PARAMS ((rtx));
121 static void delete_from_jump_chain PARAMS ((rtx));
122 static int delete_labelref_insn PARAMS ((rtx, rtx, int));
123 static void mark_modified_reg PARAMS ((rtx, rtx, void *));
124 static void redirect_tablejump PARAMS ((rtx, rtx));
125 static void jump_optimize_1 PARAMS ((rtx, int, int, int, int, int));
126 static int returnjump_p_1 PARAMS ((rtx *, void *));
127 static void delete_prior_computation PARAMS ((rtx, rtx));
129 /* Main external entry point into the jump optimizer. See comments before
130 jump_optimize_1 for descriptions of the arguments. */
132 jump_optimize (f, cross_jump, noop_moves, after_regscan)
138 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0, 0);
141 /* Alternate entry into the jump optimizer. This entry point only rebuilds
142 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
145 rebuild_jump_labels (f)
148 jump_optimize_1 (f, 0, 0, 0, 1, 0);
151 /* Alternate entry into the jump optimizer. Do only trivial optimizations. */
154 jump_optimize_minimal (f)
157 jump_optimize_1 (f, 0, 0, 0, 0, 1);
160 /* Delete no-op jumps and optimize jumps to jumps
161 and jumps around jumps.
162 Delete unused labels and unreachable code.
164 If CROSS_JUMP is 1, detect matching code
165 before a jump and its destination and unify them.
166 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
168 If NOOP_MOVES is nonzero, delete no-op move insns.
170 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
171 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
173 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
174 and JUMP_LABEL field for jumping insns.
176 If `optimize' is zero, don't change any code,
177 just determine whether control drops off the end of the function.
178 This case occurs when we have -W and not -O.
179 It works because `delete_insn' checks the value of `optimize'
180 and refrains from actually deleting when that is 0.
182 If MINIMAL is nonzero, then we only perform trivial optimizations:
184 * Removal of unreachable code after BARRIERs.
185 * Removal of unreferenced CODE_LABELs.
186 * Removal of a jump to the next instruction.
187 * Removal of a conditional jump followed by an unconditional jump
188 to the same target as the conditional jump.
189 * Simplify a conditional jump around an unconditional jump.
190 * Simplify a jump to a jump.
191 * Delete extraneous line number notes.
195 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan,
196 mark_labels_only, minimal)
201 int mark_labels_only;
204 register rtx insn, next;
210 enum rtx_code reversed_code;
212 cross_jump_death_matters = (cross_jump == 2);
213 max_uid = init_label_info (f) + 1;
215 /* If we are performing cross jump optimizations, then initialize
216 tables mapping UIDs to EH regions to avoid incorrect movement
217 of insns from one EH region to another. */
218 if (flag_exceptions && cross_jump)
219 init_insn_eh_region (f, max_uid);
221 if (! mark_labels_only)
222 delete_barrier_successors (f);
224 /* Leave some extra room for labels and duplicate exit test insns
226 max_jump_chain = max_uid * 14 / 10;
227 jump_chain = (rtx *) xcalloc (max_jump_chain, sizeof (rtx));
229 mark_all_labels (f, cross_jump);
231 /* Keep track of labels used from static data; we don't track them
232 closely enough to delete them here, so make sure their reference
233 count doesn't drop to zero. */
235 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
236 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
237 LABEL_NUSES (XEXP (insn, 0))++;
239 check_exception_handler_labels ();
241 /* Keep track of labels used for marking handlers for exception
242 regions; they cannot usually be deleted. */
244 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
245 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
246 LABEL_NUSES (XEXP (insn, 0))++;
248 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
249 notes and recompute LABEL_NUSES. */
250 if (mark_labels_only)
254 exception_optimize ();
256 last_insn = delete_unreferenced_labels (f);
259 delete_noop_moves (f);
261 /* If we haven't yet gotten to reload and we have just run regscan,
262 delete any insn that sets a register that isn't used elsewhere.
263 This helps some of the optimizations below by having less insns
264 being jumped around. */
266 if (optimize && ! reload_completed && after_regscan)
267 for (insn = f; insn; insn = next)
269 rtx set = single_set (insn);
271 next = NEXT_INSN (insn);
273 if (set && GET_CODE (SET_DEST (set)) == REG
274 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
275 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
276 /* We use regno_last_note_uid so as not to delete the setting
277 of a reg that's used in notes. A subsequent optimization
278 might arrange to use that reg for real. */
279 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
280 && ! side_effects_p (SET_SRC (set))
281 && ! find_reg_note (insn, REG_RETVAL, 0)
282 /* An ADDRESSOF expression can turn into a use of the internal arg
283 pointer, so do not delete the initialization of the internal
284 arg pointer yet. If it is truly dead, flow will delete the
285 initializing insn. */
286 && SET_DEST (set) != current_function_internal_arg_pointer)
290 /* Now iterate optimizing jumps until nothing changes over one pass. */
292 old_max_reg = max_reg_num ();
297 for (insn = f; insn; insn = next)
300 rtx temp, temp1, temp2 = NULL_RTX;
301 rtx temp4 ATTRIBUTE_UNUSED;
303 int this_is_any_uncondjump;
304 int this_is_any_condjump;
305 int this_is_onlyjump;
307 next = NEXT_INSN (insn);
309 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
310 jump. Try to optimize by duplicating the loop exit test if so.
311 This is only safe immediately after regscan, because it uses
312 the values of regno_first_uid and regno_last_uid. */
313 if (after_regscan && GET_CODE (insn) == NOTE
314 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
315 && (temp1 = next_nonnote_insn (insn)) != 0
316 && any_uncondjump_p (temp1)
317 && onlyjump_p (temp1))
319 temp = PREV_INSN (insn);
320 if (duplicate_loop_exit_test (insn))
323 next = NEXT_INSN (temp);
328 if (GET_CODE (insn) != JUMP_INSN)
331 this_is_any_condjump = any_condjump_p (insn);
332 this_is_any_uncondjump = any_uncondjump_p (insn);
333 this_is_onlyjump = onlyjump_p (insn);
335 /* Tension the labels in dispatch tables. */
337 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
338 changed |= tension_vector_labels (PATTERN (insn), 0);
339 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
340 changed |= tension_vector_labels (PATTERN (insn), 1);
342 /* See if this jump goes to another jump and redirect if so. */
343 nlabel = follow_jumps (JUMP_LABEL (insn));
344 if (nlabel != JUMP_LABEL (insn))
345 changed |= redirect_jump (insn, nlabel, 1);
347 if (! optimize || minimal)
350 /* If a dispatch table always goes to the same place,
351 get rid of it and replace the insn that uses it. */
353 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
354 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
357 rtx pat = PATTERN (insn);
358 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
359 int len = XVECLEN (pat, diff_vec_p);
360 rtx dispatch = prev_real_insn (insn);
363 for (i = 0; i < len; i++)
364 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
365 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
370 && GET_CODE (dispatch) == JUMP_INSN
371 && JUMP_LABEL (dispatch) != 0
372 /* Don't mess with a casesi insn.
373 XXX according to the comment before computed_jump_p(),
374 all casesi insns should be a parallel of the jump
375 and a USE of a LABEL_REF. */
376 && ! ((set = single_set (dispatch)) != NULL
377 && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE))
378 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
380 redirect_tablejump (dispatch,
381 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
386 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
388 /* Detect jump to following insn. */
389 if (reallabelprev == insn
390 && (this_is_any_condjump || this_is_any_uncondjump)
393 next = next_real_insn (JUMP_LABEL (insn));
396 /* Remove the "inactive" but "real" insns (i.e. uses and
397 clobbers) in between here and there. */
399 while ((temp = next_real_insn (temp)) != next)
406 /* Detect a conditional jump going to the same place
407 as an immediately following unconditional jump. */
408 else if (this_is_any_condjump && this_is_onlyjump
409 && (temp = next_active_insn (insn)) != 0
410 && simplejump_p (temp)
411 && (next_active_insn (JUMP_LABEL (insn))
412 == next_active_insn (JUMP_LABEL (temp))))
414 /* Don't mess up test coverage analysis. */
416 if (flag_test_coverage && !reload_completed)
417 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
418 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
423 /* Ensure that we jump to the later of the two labels.
434 If we leave the goto L1, we'll incorrectly leave
435 return-reg dead for TEST true. */
437 temp2 = next_active_insn (JUMP_LABEL (insn));
439 temp2 = get_last_insn ();
440 if (GET_CODE (temp2) != CODE_LABEL)
441 temp2 = prev_label (temp2);
442 if (temp2 != JUMP_LABEL (temp))
443 redirect_jump (temp, temp2, 1);
451 /* Detect a conditional jump jumping over an unconditional jump. */
453 else if (this_is_any_condjump
454 && reallabelprev != 0
455 && GET_CODE (reallabelprev) == JUMP_INSN
456 && prev_active_insn (reallabelprev) == insn
457 && no_labels_between_p (insn, reallabelprev)
458 && any_uncondjump_p (reallabelprev)
459 && onlyjump_p (reallabelprev))
461 /* When we invert the unconditional jump, we will be
462 decrementing the usage count of its old label.
463 Make sure that we don't delete it now because that
464 might cause the following code to be deleted. */
465 rtx prev_uses = prev_nonnote_insn (reallabelprev);
466 rtx prev_label = JUMP_LABEL (insn);
469 ++LABEL_NUSES (prev_label);
471 if (invert_jump (insn, JUMP_LABEL (reallabelprev), 1))
473 /* It is very likely that if there are USE insns before
474 this jump, they hold REG_DEAD notes. These REG_DEAD
475 notes are no longer valid due to this optimization,
476 and will cause the life-analysis that following passes
477 (notably delayed-branch scheduling) to think that
478 these registers are dead when they are not.
480 To prevent this trouble, we just remove the USE insns
481 from the insn chain. */
483 while (prev_uses && GET_CODE (prev_uses) == INSN
484 && GET_CODE (PATTERN (prev_uses)) == USE)
486 rtx useless = prev_uses;
487 prev_uses = prev_nonnote_insn (prev_uses);
488 delete_insn (useless);
491 delete_insn (reallabelprev);
495 /* We can now safely delete the label if it is unreferenced
496 since the delete_insn above has deleted the BARRIER. */
497 if (prev_label && --LABEL_NUSES (prev_label) == 0)
498 delete_insn (prev_label);
500 next = NEXT_INSN (insn);
503 /* If we have an unconditional jump preceded by a USE, try to put
504 the USE before the target and jump there. This simplifies many
505 of the optimizations below since we don't have to worry about
506 dealing with these USE insns. We only do this if the label
507 being branch to already has the identical USE or if code
508 never falls through to that label. */
510 else if (this_is_any_uncondjump
511 && (temp = prev_nonnote_insn (insn)) != 0
512 && GET_CODE (temp) == INSN
513 && GET_CODE (PATTERN (temp)) == USE
514 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
515 && (GET_CODE (temp1) == BARRIER
516 || (GET_CODE (temp1) == INSN
517 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
518 /* Don't do this optimization if we have a loop containing
519 only the USE instruction, and the loop start label has
520 a usage count of 1. This is because we will redo this
521 optimization everytime through the outer loop, and jump
522 opt will never exit. */
523 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
524 && temp2 == JUMP_LABEL (insn)
525 && LABEL_NUSES (temp2) == 1))
527 if (GET_CODE (temp1) == BARRIER)
529 emit_insn_after (PATTERN (temp), temp1);
530 temp1 = NEXT_INSN (temp1);
534 redirect_jump (insn, get_label_before (temp1), 1);
535 reallabelprev = prev_real_insn (temp1);
537 next = NEXT_INSN (insn);
541 /* Detect a conditional jump jumping over an unconditional trap. */
543 && this_is_any_condjump && this_is_onlyjump
544 && reallabelprev != 0
545 && GET_CODE (reallabelprev) == INSN
546 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
547 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
548 && prev_active_insn (reallabelprev) == insn
549 && no_labels_between_p (insn, reallabelprev)
550 && (temp2 = get_condition (insn, &temp4))
551 && ((reversed_code = reversed_comparison_code (temp2, insn))
554 rtx new = gen_cond_trap (reversed_code,
555 XEXP (temp2, 0), XEXP (temp2, 1),
556 TRAP_CODE (PATTERN (reallabelprev)));
560 emit_insn_before (new, temp4);
561 delete_insn (reallabelprev);
567 /* Detect a jump jumping to an unconditional trap. */
568 else if (HAVE_trap && this_is_onlyjump
569 && (temp = next_active_insn (JUMP_LABEL (insn)))
570 && GET_CODE (temp) == INSN
571 && GET_CODE (PATTERN (temp)) == TRAP_IF
572 && (this_is_any_uncondjump
573 || (this_is_any_condjump
574 && (temp2 = get_condition (insn, &temp4)))))
576 rtx tc = TRAP_CONDITION (PATTERN (temp));
578 if (tc == const_true_rtx
579 || (! this_is_any_uncondjump && rtx_equal_p (temp2, tc)))
582 /* Replace an unconditional jump to a trap with a trap. */
583 if (this_is_any_uncondjump)
585 emit_barrier_after (emit_insn_before (gen_trap (), insn));
590 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
592 TRAP_CODE (PATTERN (temp)));
595 emit_insn_before (new, temp4);
601 /* If the trap condition and jump condition are mutually
602 exclusive, redirect the jump to the following insn. */
603 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
604 && this_is_any_condjump
605 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
606 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
607 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
608 && redirect_jump (insn, get_label_after (temp), 1))
617 /* Now that the jump has been tensioned,
618 try cross jumping: check for identical code
619 before the jump and before its target label. */
621 /* First, cross jumping of conditional jumps: */
623 if (cross_jump && condjump_p (insn))
625 rtx newjpos, newlpos;
626 rtx x = prev_real_insn (JUMP_LABEL (insn));
628 /* A conditional jump may be crossjumped
629 only if the place it jumps to follows
630 an opposing jump that comes back here. */
632 if (x != 0 && ! jump_back_p (x, insn))
633 /* We have no opposing jump;
634 cannot cross jump this insn. */
638 /* TARGET is nonzero if it is ok to cross jump
639 to code before TARGET. If so, see if matches. */
641 find_cross_jump (insn, x, 2,
646 do_cross_jump (insn, newjpos, newlpos);
647 /* Make the old conditional jump
648 into an unconditional one. */
649 SET_SRC (PATTERN (insn))
650 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
651 INSN_CODE (insn) = -1;
652 emit_barrier_after (insn);
653 /* Add to jump_chain unless this is a new label
654 whose UID is too large. */
655 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
657 jump_chain[INSN_UID (insn)]
658 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
659 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
666 /* Cross jumping of unconditional jumps:
667 a few differences. */
669 if (cross_jump && simplejump_p (insn))
671 rtx newjpos, newlpos;
676 /* TARGET is nonzero if it is ok to cross jump
677 to code before TARGET. If so, see if matches. */
678 find_cross_jump (insn, JUMP_LABEL (insn), 1,
681 /* If cannot cross jump to code before the label,
682 see if we can cross jump to another jump to
684 /* Try each other jump to this label. */
685 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
686 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
687 target != 0 && newjpos == 0;
688 target = jump_chain[INSN_UID (target)])
690 && JUMP_LABEL (target) == JUMP_LABEL (insn)
691 /* Ignore TARGET if it's deleted. */
692 && ! INSN_DELETED_P (target))
693 find_cross_jump (insn, target, 2,
698 do_cross_jump (insn, newjpos, newlpos);
704 /* This code was dead in the previous jump.c! */
705 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
707 /* Return insns all "jump to the same place"
708 so we can cross-jump between any two of them. */
710 rtx newjpos, newlpos, target;
714 /* If cannot cross jump to code before the label,
715 see if we can cross jump to another jump to
717 /* Try each other jump to this label. */
718 for (target = jump_chain[0];
719 target != 0 && newjpos == 0;
720 target = jump_chain[INSN_UID (target)])
722 && ! INSN_DELETED_P (target)
723 && GET_CODE (PATTERN (target)) == RETURN)
724 find_cross_jump (insn, target, 2,
729 do_cross_jump (insn, newjpos, newlpos);
740 /* Delete extraneous line number notes.
741 Note that two consecutive notes for different lines are not really
742 extraneous. There should be some indication where that line belonged,
743 even if it became empty. */
748 for (insn = f; insn; insn = NEXT_INSN (insn))
749 if (GET_CODE (insn) == NOTE)
751 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
752 /* Any previous line note was for the prologue; gdb wants a new
753 note after the prologue even if it is for the same line. */
754 last_note = NULL_RTX;
755 else if (NOTE_LINE_NUMBER (insn) >= 0)
757 /* Delete this note if it is identical to previous note. */
759 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
760 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
777 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
778 notes whose labels don't occur in the insn any more. Returns the
779 largest INSN_UID found. */
787 for (insn = f; insn; insn = NEXT_INSN (insn))
789 if (GET_CODE (insn) == CODE_LABEL)
790 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
791 else if (GET_CODE (insn) == JUMP_INSN)
792 JUMP_LABEL (insn) = 0;
793 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
797 for (note = REG_NOTES (insn); note; note = next)
799 next = XEXP (note, 1);
800 if (REG_NOTE_KIND (note) == REG_LABEL
801 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
802 remove_note (insn, note);
805 if (INSN_UID (insn) > largest_uid)
806 largest_uid = INSN_UID (insn);
812 /* Delete insns following barriers, up to next label.
814 Also delete no-op jumps created by gcse. */
817 delete_barrier_successors (f)
823 for (insn = f; insn;)
825 if (GET_CODE (insn) == BARRIER)
827 insn = NEXT_INSN (insn);
829 never_reached_warning (insn);
831 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
833 if (GET_CODE (insn) == NOTE
834 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
835 insn = NEXT_INSN (insn);
837 insn = delete_insn (insn);
839 /* INSN is now the code_label. */
842 /* Also remove (set (pc) (pc)) insns which can be created by
843 gcse. We eliminate such insns now to avoid having them
844 cause problems later. */
845 else if (GET_CODE (insn) == JUMP_INSN
846 && (set = pc_set (insn)) != NULL
847 && SET_SRC (set) == pc_rtx
848 && SET_DEST (set) == pc_rtx
849 && onlyjump_p (insn))
850 insn = delete_insn (insn);
853 insn = NEXT_INSN (insn);
857 /* Mark the label each jump jumps to.
858 Combine consecutive labels, and count uses of labels.
860 For each label, make a chain (using `jump_chain')
861 of all the *unconditional* jumps that jump to it;
862 also make a chain of all returns.
864 CROSS_JUMP indicates whether we are doing cross jumping
865 and if we are whether we will be paying attention to
866 death notes or not. */
869 mark_all_labels (f, cross_jump)
875 for (insn = f; insn; insn = NEXT_INSN (insn))
878 if (GET_CODE (insn) == CALL_INSN
879 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
881 mark_all_labels (XEXP (PATTERN (insn), 0), cross_jump);
882 mark_all_labels (XEXP (PATTERN (insn), 1), cross_jump);
883 mark_all_labels (XEXP (PATTERN (insn), 2), cross_jump);
887 mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
888 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
890 /* When we know the LABEL_REF contained in a REG used in
891 an indirect jump, we'll have a REG_LABEL note so that
892 flow can tell where it's going. */
893 if (JUMP_LABEL (insn) == 0)
895 rtx label_note = find_reg_note (insn, REG_LABEL, NULL_RTX);
898 /* But a LABEL_REF around the REG_LABEL note, so
899 that we can canonicalize it. */
900 rtx label_ref = gen_rtx_LABEL_REF (VOIDmode,
901 XEXP (label_note, 0));
903 mark_jump_label (label_ref, insn, cross_jump, 0);
904 XEXP (label_note, 0) = XEXP (label_ref, 0);
905 JUMP_LABEL (insn) = XEXP (label_note, 0);
908 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
910 jump_chain[INSN_UID (insn)]
911 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
912 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
914 if (GET_CODE (PATTERN (insn)) == RETURN)
916 jump_chain[INSN_UID (insn)] = jump_chain[0];
917 jump_chain[0] = insn;
923 /* Delete all labels already not referenced.
924 Also find and return the last insn. */
927 delete_unreferenced_labels (f)
930 rtx final = NULL_RTX;
933 for (insn = f; insn;)
935 if (GET_CODE (insn) == CODE_LABEL
936 && LABEL_NUSES (insn) == 0
937 && LABEL_ALTERNATE_NAME (insn) == NULL)
938 insn = delete_insn (insn);
942 insn = NEXT_INSN (insn);
949 /* Delete various simple forms of moves which have no necessary
953 delete_noop_moves (f)
958 for (insn = f; insn;)
960 next = NEXT_INSN (insn);
962 if (GET_CODE (insn) == INSN)
964 register rtx body = PATTERN (insn);
966 /* Detect and delete no-op move instructions
967 resulting from not allocating a parameter in a register. */
969 if (GET_CODE (body) == SET
970 && (SET_DEST (body) == SET_SRC (body)
971 || (GET_CODE (SET_DEST (body)) == MEM
972 && GET_CODE (SET_SRC (body)) == MEM
973 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
974 && ! (GET_CODE (SET_DEST (body)) == MEM
975 && MEM_VOLATILE_P (SET_DEST (body)))
976 && ! (GET_CODE (SET_SRC (body)) == MEM
977 && MEM_VOLATILE_P (SET_SRC (body))))
978 delete_computation (insn);
980 /* Detect and ignore no-op move instructions
981 resulting from smart or fortuitous register allocation. */
983 else if (GET_CODE (body) == SET)
985 int sreg = true_regnum (SET_SRC (body));
986 int dreg = true_regnum (SET_DEST (body));
988 if (sreg == dreg && sreg >= 0)
990 else if (sreg >= 0 && dreg >= 0)
993 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
994 sreg, NULL_PTR, dreg,
995 GET_MODE (SET_SRC (body)));
998 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
1000 /* DREG may have been the target of a REG_DEAD note in
1001 the insn which makes INSN redundant. If so, reorg
1002 would still think it is dead. So search for such a
1003 note and delete it if we find it. */
1004 if (! find_regno_note (insn, REG_UNUSED, dreg))
1005 for (trial = prev_nonnote_insn (insn);
1006 trial && GET_CODE (trial) != CODE_LABEL;
1007 trial = prev_nonnote_insn (trial))
1008 if (find_regno_note (trial, REG_DEAD, dreg))
1010 remove_death (dreg, trial);
1014 /* Deleting insn could lose a death-note for SREG. */
1015 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
1017 /* Change this into a USE so that we won't emit
1018 code for it, but still can keep the note. */
1020 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
1021 INSN_CODE (insn) = -1;
1022 /* Remove all reg notes but the REG_DEAD one. */
1023 REG_NOTES (insn) = trial;
1024 XEXP (trial, 1) = NULL_RTX;
1030 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
1031 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
1033 GET_MODE (SET_DEST (body))))
1035 /* This handles the case where we have two consecutive
1036 assignments of the same constant to pseudos that didn't
1037 get a hard reg. Each SET from the constant will be
1038 converted into a SET of the spill register and an
1039 output reload will be made following it. This produces
1040 two loads of the same constant into the same spill
1045 /* Look back for a death note for the first reg.
1046 If there is one, it is no longer accurate. */
1047 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
1049 if ((GET_CODE (in_insn) == INSN
1050 || GET_CODE (in_insn) == JUMP_INSN)
1051 && find_regno_note (in_insn, REG_DEAD, dreg))
1053 remove_death (dreg, in_insn);
1056 in_insn = PREV_INSN (in_insn);
1059 /* Delete the second load of the value. */
1063 else if (GET_CODE (body) == PARALLEL)
1065 /* If each part is a set between two identical registers or
1066 a USE or CLOBBER, delete the insn. */
1070 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
1072 tem = XVECEXP (body, 0, i);
1073 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
1076 if (GET_CODE (tem) != SET
1077 || (sreg = true_regnum (SET_SRC (tem))) < 0
1078 || (dreg = true_regnum (SET_DEST (tem))) < 0
1086 /* Also delete insns to store bit fields if they are no-ops. */
1087 /* Not worth the hair to detect this in the big-endian case. */
1088 else if (! BYTES_BIG_ENDIAN
1089 && GET_CODE (body) == SET
1090 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
1091 && XEXP (SET_DEST (body), 2) == const0_rtx
1092 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
1093 && ! (GET_CODE (SET_SRC (body)) == MEM
1094 && MEM_VOLATILE_P (SET_SRC (body))))
1101 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1102 jump. Assume that this unconditional jump is to the exit test code. If
1103 the code is sufficiently simple, make a copy of it before INSN,
1104 followed by a jump to the exit of the loop. Then delete the unconditional
1107 Return 1 if we made the change, else 0.
1109 This is only safe immediately after a regscan pass because it uses the
1110 values of regno_first_uid and regno_last_uid. */
1113 duplicate_loop_exit_test (loop_start)
1116 rtx insn, set, reg, p, link;
1117 rtx copy = 0, first_copy = 0;
1119 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
1121 int max_reg = max_reg_num ();
1124 /* Scan the exit code. We do not perform this optimization if any insn:
1128 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1129 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1130 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1133 We also do not do this if we find an insn with ASM_OPERANDS. While
1134 this restriction should not be necessary, copying an insn with
1135 ASM_OPERANDS can confuse asm_noperands in some cases.
1137 Also, don't do this if the exit code is more than 20 insns. */
1139 for (insn = exitcode;
1141 && ! (GET_CODE (insn) == NOTE
1142 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
1143 insn = NEXT_INSN (insn))
1145 switch (GET_CODE (insn))
1151 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
1152 a jump immediately after the loop start that branches outside
1153 the loop but within an outer loop, near the exit test.
1154 If we copied this exit test and created a phony
1155 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
1156 before the exit test look like these could be safely moved
1157 out of the loop even if they actually may be never executed.
1158 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
1160 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1161 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
1165 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1166 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
1167 /* If we were to duplicate this code, we would not move
1168 the BLOCK notes, and so debugging the moved code would
1169 be difficult. Thus, we only move the code with -O2 or
1176 /* The code below would grossly mishandle REG_WAS_0 notes,
1177 so get rid of them here. */
1178 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
1179 remove_note (insn, p);
1180 if (++num_insns > 20
1181 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1182 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
1190 /* Unless INSN is zero, we can do the optimization. */
1196 /* See if any insn sets a register only used in the loop exit code and
1197 not a user variable. If so, replace it with a new register. */
1198 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1199 if (GET_CODE (insn) == INSN
1200 && (set = single_set (insn)) != 0
1201 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
1202 || (GET_CODE (reg) == SUBREG
1203 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
1204 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
1205 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
1207 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
1208 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
1213 /* We can do the replacement. Allocate reg_map if this is the
1214 first replacement we found. */
1216 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
1218 REG_LOOP_TEST_P (reg) = 1;
1220 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
1224 /* Now copy each insn. */
1225 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1227 switch (GET_CODE (insn))
1230 copy = emit_barrier_before (loop_start);
1233 /* Only copy line-number notes. */
1234 if (NOTE_LINE_NUMBER (insn) >= 0)
1236 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
1237 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
1242 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
1244 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1246 mark_jump_label (PATTERN (copy), copy, 0, 0);
1248 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1250 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1251 if (REG_NOTE_KIND (link) != REG_LABEL)
1253 if (GET_CODE (link) == EXPR_LIST)
1255 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
1260 = copy_insn_1 (gen_rtx_INSN_LIST (REG_NOTE_KIND (link),
1265 if (reg_map && REG_NOTES (copy))
1266 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1270 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)),
1273 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1274 mark_jump_label (PATTERN (copy), copy, 0, 0);
1275 if (REG_NOTES (insn))
1277 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
1279 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1282 /* If this is a simple jump, add it to the jump chain. */
1284 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
1285 && simplejump_p (copy))
1287 jump_chain[INSN_UID (copy)]
1288 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1289 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1297 /* Record the first insn we copied. We need it so that we can
1298 scan the copied insns for new pseudo registers. */
1303 /* Now clean up by emitting a jump to the end label and deleting the jump
1304 at the start of the loop. */
1305 if (! copy || GET_CODE (copy) != BARRIER)
1307 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
1310 /* Record the first insn we copied. We need it so that we can
1311 scan the copied insns for new pseudo registers. This may not
1312 be strictly necessary since we should have copied at least one
1313 insn above. But I am going to be safe. */
1317 mark_jump_label (PATTERN (copy), copy, 0, 0);
1318 if (INSN_UID (copy) < max_jump_chain
1319 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
1321 jump_chain[INSN_UID (copy)]
1322 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1323 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1325 emit_barrier_before (loop_start);
1328 /* Now scan from the first insn we copied to the last insn we copied
1329 (copy) for new pseudo registers. Do this after the code to jump to
1330 the end label since that might create a new pseudo too. */
1331 reg_scan_update (first_copy, copy, max_reg);
1333 /* Mark the exit code as the virtual top of the converted loop. */
1334 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
1336 delete_insn (next_nonnote_insn (loop_start));
1345 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
1346 notes between START and END out before START. Assume that END is not
1347 such a note. START may be such a note. Returns the value of the new
1348 starting insn, which may be different if the original start was such a
1352 squeeze_notes (start, end)
1358 for (insn = start; insn != end; insn = next)
1360 next = NEXT_INSN (insn);
1361 if (GET_CODE (insn) == NOTE
1362 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
1363 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1364 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1365 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
1366 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
1367 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
1373 rtx prev = PREV_INSN (insn);
1374 PREV_INSN (insn) = PREV_INSN (start);
1375 NEXT_INSN (insn) = start;
1376 NEXT_INSN (PREV_INSN (insn)) = insn;
1377 PREV_INSN (NEXT_INSN (insn)) = insn;
1378 NEXT_INSN (prev) = next;
1379 PREV_INSN (next) = prev;
1387 /* Compare the instructions before insn E1 with those before E2
1388 to find an opportunity for cross jumping.
1389 (This means detecting identical sequences of insns followed by
1390 jumps to the same place, or followed by a label and a jump
1391 to that label, and replacing one with a jump to the other.)
1393 Assume E1 is a jump that jumps to label E2
1394 (that is not always true but it might as well be).
1395 Find the longest possible equivalent sequences
1396 and store the first insns of those sequences into *F1 and *F2.
1397 Store zero there if no equivalent preceding instructions are found.
1399 We give up if we find a label in stream 1.
1400 Actually we could transfer that label into stream 2. */
1403 find_cross_jump (e1, e2, minimum, f1, f2)
1408 register rtx i1 = e1, i2 = e2;
1409 register rtx p1, p2;
1412 rtx last1 = 0, last2 = 0;
1413 rtx afterlast1 = 0, afterlast2 = 0;
1420 i1 = prev_nonnote_insn (i1);
1422 i2 = PREV_INSN (i2);
1423 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
1424 i2 = PREV_INSN (i2);
1429 /* Don't allow the range of insns preceding E1 or E2
1430 to include the other (E2 or E1). */
1431 if (i2 == e1 || i1 == e2)
1434 /* If we will get to this code by jumping, those jumps will be
1435 tensioned to go directly to the new label (before I2),
1436 so this cross-jumping won't cost extra. So reduce the minimum. */
1437 if (GET_CODE (i1) == CODE_LABEL)
1443 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
1446 /* Avoid moving insns across EH regions if either of the insns
1449 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
1450 && !in_same_eh_region (i1, i2))
1456 /* If this is a CALL_INSN, compare register usage information.
1457 If we don't check this on stack register machines, the two
1458 CALL_INSNs might be merged leaving reg-stack.c with mismatching
1459 numbers of stack registers in the same basic block.
1460 If we don't check this on machines with delay slots, a delay slot may
1461 be filled that clobbers a parameter expected by the subroutine.
1463 ??? We take the simple route for now and assume that if they're
1464 equal, they were constructed identically. */
1466 if (GET_CODE (i1) == CALL_INSN
1467 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1468 CALL_INSN_FUNCTION_USAGE (i2)))
1472 /* If cross_jump_death_matters is not 0, the insn's mode
1473 indicates whether or not the insn contains any stack-like
1476 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
1478 /* If register stack conversion has already been done, then
1479 death notes must also be compared before it is certain that
1480 the two instruction streams match. */
1483 HARD_REG_SET i1_regset, i2_regset;
1485 CLEAR_HARD_REG_SET (i1_regset);
1486 CLEAR_HARD_REG_SET (i2_regset);
1488 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
1489 if (REG_NOTE_KIND (note) == REG_DEAD
1490 && STACK_REG_P (XEXP (note, 0)))
1491 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
1493 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1494 if (REG_NOTE_KIND (note) == REG_DEAD
1495 && STACK_REG_P (XEXP (note, 0)))
1496 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1498 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
1507 /* Don't allow old-style asm or volatile extended asms to be accepted
1508 for cross jumping purposes. It is conceptually correct to allow
1509 them, since cross-jumping preserves the dynamic instruction order
1510 even though it is changing the static instruction order. However,
1511 if an asm is being used to emit an assembler pseudo-op, such as
1512 the MIPS `.set reorder' pseudo-op, then the static instruction order
1513 matters and it must be preserved. */
1514 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
1515 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
1516 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
1519 if (lose || GET_CODE (p1) != GET_CODE (p2)
1520 || ! rtx_renumbered_equal_p (p1, p2))
1522 /* The following code helps take care of G++ cleanups. */
1526 if (!lose && GET_CODE (p1) == GET_CODE (p2)
1527 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
1528 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
1529 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
1530 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
1531 /* If the equivalences are not to a constant, they may
1532 reference pseudos that no longer exist, so we can't
1534 && CONSTANT_P (XEXP (equiv1, 0))
1535 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1537 rtx s1 = single_set (i1);
1538 rtx s2 = single_set (i2);
1539 if (s1 != 0 && s2 != 0
1540 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
1542 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
1543 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
1544 if (! rtx_renumbered_equal_p (p1, p2))
1546 else if (apply_change_group ())
1551 /* Insns fail to match; cross jumping is limited to the following
1555 /* Don't allow the insn after a compare to be shared by
1556 cross-jumping unless the compare is also shared.
1557 Here, if either of these non-matching insns is a compare,
1558 exclude the following insn from possible cross-jumping. */
1559 if (sets_cc0_p (p1) || sets_cc0_p (p2))
1560 last1 = afterlast1, last2 = afterlast2, ++minimum;
1563 /* If cross-jumping here will feed a jump-around-jump
1564 optimization, this jump won't cost extra, so reduce
1566 if (GET_CODE (i1) == JUMP_INSN
1568 && prev_real_insn (JUMP_LABEL (i1)) == e1)
1574 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
1576 /* Ok, this insn is potentially includable in a cross-jump here. */
1577 afterlast1 = last1, afterlast2 = last2;
1578 last1 = i1, last2 = i2, --minimum;
1582 if (minimum <= 0 && last1 != 0 && last1 != e1)
1583 *f1 = last1, *f2 = last2;
1587 do_cross_jump (insn, newjpos, newlpos)
1588 rtx insn, newjpos, newlpos;
1590 /* Find an existing label at this point
1591 or make a new one if there is none. */
1592 register rtx label = get_label_before (newlpos);
1594 /* Make the same jump insn jump to the new point. */
1595 if (GET_CODE (PATTERN (insn)) == RETURN)
1597 /* Remove from jump chain of returns. */
1598 delete_from_jump_chain (insn);
1599 /* Change the insn. */
1600 PATTERN (insn) = gen_jump (label);
1601 INSN_CODE (insn) = -1;
1602 JUMP_LABEL (insn) = label;
1603 LABEL_NUSES (label)++;
1604 /* Add to new the jump chain. */
1605 if (INSN_UID (label) < max_jump_chain
1606 && INSN_UID (insn) < max_jump_chain)
1608 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
1609 jump_chain[INSN_UID (label)] = insn;
1613 redirect_jump (insn, label, 1);
1615 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
1616 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
1617 the NEWJPOS stream. */
1619 while (newjpos != insn)
1623 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
1624 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
1625 || REG_NOTE_KIND (lnote) == REG_EQUIV)
1626 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
1627 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
1628 remove_note (newlpos, lnote);
1630 delete_insn (newjpos);
1631 newjpos = next_real_insn (newjpos);
1632 newlpos = next_real_insn (newlpos);
1636 /* Return the label before INSN, or put a new label there. */
1639 get_label_before (insn)
1644 /* Find an existing label at this point
1645 or make a new one if there is none. */
1646 label = prev_nonnote_insn (insn);
1648 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1650 rtx prev = PREV_INSN (insn);
1652 label = gen_label_rtx ();
1653 emit_label_after (label, prev);
1654 LABEL_NUSES (label) = 0;
1659 /* Return the label after INSN, or put a new label there. */
1662 get_label_after (insn)
1667 /* Find an existing label at this point
1668 or make a new one if there is none. */
1669 label = next_nonnote_insn (insn);
1671 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1673 label = gen_label_rtx ();
1674 emit_label_after (label, insn);
1675 LABEL_NUSES (label) = 0;
1680 /* Return 1 if INSN is a jump that jumps to right after TARGET
1681 only on the condition that TARGET itself would drop through.
1682 Assumes that TARGET is a conditional jump. */
1685 jump_back_p (insn, target)
1689 enum rtx_code codei, codet;
1692 if (! any_condjump_p (insn)
1693 || any_uncondjump_p (target)
1694 || target != prev_real_insn (JUMP_LABEL (insn)))
1696 set = pc_set (insn);
1697 tset = pc_set (target);
1699 cinsn = XEXP (SET_SRC (set), 0);
1700 ctarget = XEXP (SET_SRC (tset), 0);
1702 codei = GET_CODE (cinsn);
1703 codet = GET_CODE (ctarget);
1705 if (XEXP (SET_SRC (set), 1) == pc_rtx)
1707 codei = reversed_comparison_code (cinsn, insn);
1708 if (codei == UNKNOWN)
1712 if (XEXP (SET_SRC (tset), 2) == pc_rtx)
1714 codet = reversed_comparison_code (ctarget, target);
1715 if (codei == UNKNOWN)
1719 return (codei == codet
1720 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
1721 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
1724 /* Given a comparison (CODE ARG0 ARG1), inside a insn, INSN, return an code
1725 of reversed comparison if it is possible to do so. Otherwise return UNKNOWN.
1726 UNKNOWN may be returned in case we are having CC_MODE compare and we don't
1727 know whether it's source is floating point or integer comparison. Machine
1728 description should define REVERSIBLE_CC_MODE and REVERSE_CONDITION macros
1729 to help this function avoid overhead in these cases. */
1731 reversed_comparison_code_parts (code, arg0, arg1, insn)
1732 rtx insn, arg0, arg1;
1735 enum machine_mode mode;
1737 /* If this is not actually a comparison, we can't reverse it. */
1738 if (GET_RTX_CLASS (code) != '<')
1741 mode = GET_MODE (arg0);
1742 if (mode == VOIDmode)
1743 mode = GET_MODE (arg1);
1745 /* First see if machine description supply us way to reverse the comparison.
1746 Give it priority over everything else to allow machine description to do
1748 #ifdef REVERSIBLE_CC_MODE
1749 if (GET_MODE_CLASS (mode) == MODE_CC
1750 && REVERSIBLE_CC_MODE (mode))
1752 #ifdef REVERSE_CONDITION
1753 return REVERSE_CONDITION (code, mode);
1755 return reverse_condition (code);
1759 /* Try few special cases based on the comparison code. */
1768 /* It is always safe to reverse EQ and NE, even for the floating
1769 point. Similary the unsigned comparisons are never used for
1770 floating point so we can reverse them in the default way. */
1771 return reverse_condition (code);
1776 /* In case we already see unordered comparison, we can be sure to
1777 be dealing with floating point so we don't need any more tests. */
1778 return reverse_condition_maybe_unordered (code);
1783 /* We don't have safe way to reverse these yet. */
1789 /* In case we give up IEEE compatibility, all comparisons are reversible. */
1790 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
1792 return reverse_condition (code);
1794 if (GET_MODE_CLASS (mode) == MODE_CC
1801 /* Try to search for the comparison to determine the real mode.
1802 This code is expensive, but with sane machine description it
1803 will be never used, since REVERSIBLE_CC_MODE will return true
1808 for (prev = prev_nonnote_insn (insn);
1809 prev != 0 && GET_CODE (prev) != CODE_LABEL;
1810 prev = prev_nonnote_insn (prev))
1812 rtx set = set_of (arg0, prev);
1813 if (set && GET_CODE (set) == SET
1814 && rtx_equal_p (SET_DEST (set), arg0))
1816 rtx src = SET_SRC (set);
1818 if (GET_CODE (src) == COMPARE)
1820 rtx comparison = src;
1821 arg0 = XEXP (src, 0);
1822 mode = GET_MODE (arg0);
1823 if (mode == VOIDmode)
1824 mode = GET_MODE (XEXP (comparison, 1));
1827 /* We can get past reg-reg moves. This may be usefull for model
1828 of i387 comparisons that first move flag registers around. */
1835 /* If register is clobbered in some ununderstandable way,
1842 /* An integer condition. */
1843 if (GET_CODE (arg0) == CONST_INT
1844 || (GET_MODE (arg0) != VOIDmode
1845 && GET_MODE_CLASS (mode) != MODE_CC
1846 && ! FLOAT_MODE_P (mode)))
1847 return reverse_condition (code);
1852 /* An wrapper around the previous function to take COMPARISON as rtx
1853 expression. This simplifies many callers. */
1855 reversed_comparison_code (comparison, insn)
1856 rtx comparison, insn;
1858 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
1860 return reversed_comparison_code_parts (GET_CODE (comparison),
1861 XEXP (comparison, 0),
1862 XEXP (comparison, 1), insn);
1865 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
1866 return non-zero if it is safe to reverse this comparison. It is if our
1867 floating-point is not IEEE, if this is an NE or EQ comparison, or if
1868 this is known to be an integer comparison.
1870 Use of this function is depreached and you should use
1871 REVERSED_COMPARISON_CODE bits instead.
1875 can_reverse_comparison_p (comparison, insn)
1881 /* If this is not actually a comparison, we can't reverse it. */
1882 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
1885 code = reversed_comparison_code (comparison, insn);
1886 if (code == UNKNOWN)
1889 /* The code will follow can_reverse_comparison_p with reverse_condition,
1890 so see if it will get proper result. */
1891 return (code == reverse_condition (GET_CODE (comparison)));
1894 /* Given an rtx-code for a comparison, return the code for the negated
1895 comparison. If no such code exists, return UNKNOWN.
1897 WATCH OUT! reverse_condition is not safe to use on a jump that might
1898 be acting on the results of an IEEE floating point comparison, because
1899 of the special treatment of non-signaling nans in comparisons.
1900 Use reversed_comparison_code instead. */
1903 reverse_condition (code)
1946 /* Similar, but we're allowed to generate unordered comparisons, which
1947 makes it safe for IEEE floating-point. Of course, we have to recognize
1948 that the target will support them too... */
1951 reverse_condition_maybe_unordered (code)
1954 /* Non-IEEE formats don't have unordered conditions. */
1955 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
1956 return reverse_condition (code);
1994 /* Similar, but return the code when two operands of a comparison are swapped.
1995 This IS safe for IEEE floating-point. */
1998 swap_condition (code)
2041 /* Given a comparison CODE, return the corresponding unsigned comparison.
2042 If CODE is an equality comparison or already an unsigned comparison,
2043 CODE is returned. */
2046 unsigned_condition (code)
2073 /* Similarly, return the signed version of a comparison. */
2076 signed_condition (code)
2103 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2104 truth of CODE1 implies the truth of CODE2. */
2107 comparison_dominates_p (code1, code2)
2108 enum rtx_code code1, code2;
2110 /* UNKNOWN comparison codes can happen as a result of trying to revert
2112 They can't match anything, so we have to reject them here. */
2113 if (code1 == UNKNOWN || code2 == UNKNOWN)
2122 if (code2 == UNLE || code2 == UNGE)
2127 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
2128 || code2 == ORDERED)
2133 if (code2 == UNLE || code2 == NE)
2138 if (code2 == LE || code2 == NE || code2 == ORDERED || code2 == LTGT)
2143 if (code2 == UNGE || code2 == NE)
2148 if (code2 == GE || code2 == NE || code2 == ORDERED || code2 == LTGT)
2154 if (code2 == ORDERED)
2159 if (code2 == NE || code2 == ORDERED)
2164 if (code2 == LEU || code2 == NE)
2169 if (code2 == GEU || code2 == NE)
2174 if (code2 == NE || code2 == UNEQ || code2 == UNLE || code2 == UNLT
2175 || code2 == UNGE || code2 == UNGT)
2186 /* Return 1 if INSN is an unconditional jump and nothing else. */
2192 return (GET_CODE (insn) == JUMP_INSN
2193 && GET_CODE (PATTERN (insn)) == SET
2194 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2195 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2198 /* Return nonzero if INSN is a (possibly) conditional jump
2201 Use this function is deprecated, since we need to support combined
2202 branch and compare insns. Use any_condjump_p instead whenever possible. */
2208 register rtx x = PATTERN (insn);
2210 if (GET_CODE (x) != SET
2211 || GET_CODE (SET_DEST (x)) != PC)
2215 if (GET_CODE (x) == LABEL_REF)
2218 return (GET_CODE (x) == IF_THEN_ELSE
2219 && ((GET_CODE (XEXP (x, 2)) == PC
2220 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
2221 || GET_CODE (XEXP (x, 1)) == RETURN))
2222 || (GET_CODE (XEXP (x, 1)) == PC
2223 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
2224 || GET_CODE (XEXP (x, 2)) == RETURN))));
2229 /* Return nonzero if INSN is a (possibly) conditional jump inside a
2232 Use this function is deprecated, since we need to support combined
2233 branch and compare insns. Use any_condjump_p instead whenever possible. */
2236 condjump_in_parallel_p (insn)
2239 register rtx x = PATTERN (insn);
2241 if (GET_CODE (x) != PARALLEL)
2244 x = XVECEXP (x, 0, 0);
2246 if (GET_CODE (x) != SET)
2248 if (GET_CODE (SET_DEST (x)) != PC)
2250 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2252 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2254 if (XEXP (SET_SRC (x), 2) == pc_rtx
2255 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2256 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2258 if (XEXP (SET_SRC (x), 1) == pc_rtx
2259 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2260 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2265 /* Return set of PC, otherwise NULL. */
2272 if (GET_CODE (insn) != JUMP_INSN)
2274 pat = PATTERN (insn);
2276 /* The set is allowed to appear either as the insn pattern or
2277 the first set in a PARALLEL. */
2278 if (GET_CODE (pat) == PARALLEL)
2279 pat = XVECEXP (pat, 0, 0);
2280 if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
2286 /* Return true when insn is an unconditional direct jump,
2287 possibly bundled inside a PARALLEL. */
2290 any_uncondjump_p (insn)
2293 rtx x = pc_set (insn);
2296 if (GET_CODE (SET_SRC (x)) != LABEL_REF)
2301 /* Return true when insn is a conditional jump. This function works for
2302 instructions containing PC sets in PARALLELs. The instruction may have
2303 various other effects so before removing the jump you must verify
2306 Note that unlike condjump_p it returns false for unconditional jumps. */
2309 any_condjump_p (insn)
2312 rtx x = pc_set (insn);
2317 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2320 a = GET_CODE (XEXP (SET_SRC (x), 1));
2321 b = GET_CODE (XEXP (SET_SRC (x), 2));
2323 return ((b == PC && (a == LABEL_REF || a == RETURN))
2324 || (a == PC && (b == LABEL_REF || b == RETURN)));
2327 /* Return the label of a conditional jump. */
2330 condjump_label (insn)
2333 rtx x = pc_set (insn);
2338 if (GET_CODE (x) == LABEL_REF)
2340 if (GET_CODE (x) != IF_THEN_ELSE)
2342 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
2344 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
2349 /* Return true if INSN is a (possibly conditional) return insn. */
2352 returnjump_p_1 (loc, data)
2354 void *data ATTRIBUTE_UNUSED;
2357 return x && GET_CODE (x) == RETURN;
2364 if (GET_CODE (insn) != JUMP_INSN)
2366 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
2369 /* Return true if INSN is a jump that only transfers control and
2378 if (GET_CODE (insn) != JUMP_INSN)
2381 set = single_set (insn);
2384 if (GET_CODE (SET_DEST (set)) != PC)
2386 if (side_effects_p (SET_SRC (set)))
2394 /* Return 1 if X is an RTX that does nothing but set the condition codes
2395 and CLOBBER or USE registers.
2396 Return -1 if X does explicitly set the condition codes,
2397 but also does other things. */
2401 rtx x ATTRIBUTE_UNUSED;
2403 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2405 if (GET_CODE (x) == PARALLEL)
2409 int other_things = 0;
2410 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2412 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2413 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2415 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2418 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2424 /* Follow any unconditional jump at LABEL;
2425 return the ultimate label reached by any such chain of jumps.
2426 If LABEL is not followed by a jump, return LABEL.
2427 If the chain loops or we can't find end, return LABEL,
2428 since that tells caller to avoid changing the insn.
2430 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2431 a USE or CLOBBER. */
2434 follow_jumps (label)
2439 register rtx value = label;
2444 && (insn = next_active_insn (value)) != 0
2445 && GET_CODE (insn) == JUMP_INSN
2446 && ((JUMP_LABEL (insn) != 0 && any_uncondjump_p (insn)
2447 && onlyjump_p (insn))
2448 || GET_CODE (PATTERN (insn)) == RETURN)
2449 && (next = NEXT_INSN (insn))
2450 && GET_CODE (next) == BARRIER);
2453 /* Don't chain through the insn that jumps into a loop
2454 from outside the loop,
2455 since that would create multiple loop entry jumps
2456 and prevent loop optimization. */
2458 if (!reload_completed)
2459 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2460 if (GET_CODE (tem) == NOTE
2461 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
2462 /* ??? Optional. Disables some optimizations, but makes
2463 gcov output more accurate with -O. */
2464 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
2467 /* If we have found a cycle, make the insn jump to itself. */
2468 if (JUMP_LABEL (insn) == label)
2471 tem = next_active_insn (JUMP_LABEL (insn));
2472 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
2473 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
2476 value = JUMP_LABEL (insn);
2483 /* Assuming that field IDX of X is a vector of label_refs,
2484 replace each of them by the ultimate label reached by it.
2485 Return nonzero if a change is made.
2486 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2489 tension_vector_labels (x, idx)
2495 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2497 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2498 register rtx nlabel = follow_jumps (olabel);
2499 if (nlabel && nlabel != olabel)
2501 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2502 ++LABEL_NUSES (nlabel);
2503 if (--LABEL_NUSES (olabel) == 0)
2504 delete_insn (olabel);
2511 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2512 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2513 in INSN, then store one of them in JUMP_LABEL (INSN).
2514 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2515 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2516 Also, when there are consecutive labels, canonicalize on the last of them.
2518 Note that two labels separated by a loop-beginning note
2519 must be kept distinct if we have not yet done loop-optimization,
2520 because the gap between them is where loop-optimize
2521 will want to move invariant code to. CROSS_JUMP tells us
2522 that loop-optimization is done with.
2524 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2525 two labels distinct if they are separated by only USE or CLOBBER insns. */
2528 mark_jump_label (x, insn, cross_jump, in_mem)
2534 register RTX_CODE code = GET_CODE (x);
2536 register const char *fmt;
2558 /* If this is a constant-pool reference, see if it is a label. */
2559 if (CONSTANT_POOL_ADDRESS_P (x))
2560 mark_jump_label (get_pool_constant (x), insn, cross_jump, in_mem);
2565 rtx label = XEXP (x, 0);
2570 /* Ignore remaining references to unreachable labels that
2571 have been deleted. */
2572 if (GET_CODE (label) == NOTE
2573 && NOTE_LINE_NUMBER (label) == NOTE_INSN_DELETED_LABEL)
2576 if (GET_CODE (label) != CODE_LABEL)
2579 /* Ignore references to labels of containing functions. */
2580 if (LABEL_REF_NONLOCAL_P (x))
2583 /* If there are other labels following this one,
2584 replace it with the last of the consecutive labels. */
2585 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
2587 if (GET_CODE (next) == CODE_LABEL)
2589 else if (cross_jump && GET_CODE (next) == INSN
2590 && (GET_CODE (PATTERN (next)) == USE
2591 || GET_CODE (PATTERN (next)) == CLOBBER))
2593 else if (GET_CODE (next) != NOTE)
2595 else if (! cross_jump
2596 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
2597 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
2598 /* ??? Optional. Disables some optimizations, but
2599 makes gcov output more accurate with -O. */
2600 || (flag_test_coverage
2601 && NOTE_LINE_NUMBER (next) > 0)))
2605 XEXP (x, 0) = label;
2606 if (! insn || ! INSN_DELETED_P (insn))
2607 ++LABEL_NUSES (label);
2611 if (GET_CODE (insn) == JUMP_INSN)
2612 JUMP_LABEL (insn) = label;
2614 /* If we've changed OLABEL and we had a REG_LABEL note
2615 for it, update it as well. */
2616 else if (label != olabel
2617 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
2618 XEXP (note, 0) = label;
2620 /* Otherwise, add a REG_LABEL note for LABEL unless there already
2622 else if (! find_reg_note (insn, REG_LABEL, label))
2624 /* This code used to ignore labels which refered to dispatch
2625 tables to avoid flow.c generating worse code.
2627 However, in the presense of global optimizations like
2628 gcse which call find_basic_blocks without calling
2629 life_analysis, not recording such labels will lead
2630 to compiler aborts because of inconsistencies in the
2631 flow graph. So we go ahead and record the label.
2633 It may also be the case that the optimization argument
2634 is no longer valid because of the more accurate cfg
2635 we build in find_basic_blocks -- it no longer pessimizes
2636 code when it finds a REG_LABEL note. */
2637 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
2644 /* Do walk the labels in a vector, but not the first operand of an
2645 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2648 if (! INSN_DELETED_P (insn))
2650 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
2652 for (i = 0; i < XVECLEN (x, eltnum); i++)
2653 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX,
2654 cross_jump, in_mem);
2662 fmt = GET_RTX_FORMAT (code);
2663 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2666 mark_jump_label (XEXP (x, i), insn, cross_jump, in_mem);
2667 else if (fmt[i] == 'E')
2670 for (j = 0; j < XVECLEN (x, i); j++)
2671 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump, in_mem);
2676 /* If all INSN does is set the pc, delete it,
2677 and delete the insn that set the condition codes for it
2678 if that's what the previous thing was. */
2684 register rtx set = single_set (insn);
2686 if (set && GET_CODE (SET_DEST (set)) == PC)
2687 delete_computation (insn);
2690 /* Verify INSN is a BARRIER and delete it. */
2693 delete_barrier (insn)
2696 if (GET_CODE (insn) != BARRIER)
2702 /* Recursively delete prior insns that compute the value (used only by INSN
2703 which the caller is deleting) stored in the register mentioned by NOTE
2704 which is a REG_DEAD note associated with INSN. */
2707 delete_prior_computation (note, insn)
2712 rtx reg = XEXP (note, 0);
2714 for (our_prev = prev_nonnote_insn (insn);
2715 our_prev && (GET_CODE (our_prev) == INSN
2716 || GET_CODE (our_prev) == CALL_INSN);
2717 our_prev = prev_nonnote_insn (our_prev))
2719 rtx pat = PATTERN (our_prev);
2721 /* If we reach a CALL which is not calling a const function
2722 or the callee pops the arguments, then give up. */
2723 if (GET_CODE (our_prev) == CALL_INSN
2724 && (! CONST_CALL_P (our_prev)
2725 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
2728 /* If we reach a SEQUENCE, it is too complex to try to
2729 do anything with it, so give up. */
2730 if (GET_CODE (pat) == SEQUENCE)
2733 if (GET_CODE (pat) == USE
2734 && GET_CODE (XEXP (pat, 0)) == INSN)
2735 /* reorg creates USEs that look like this. We leave them
2736 alone because reorg needs them for its own purposes. */
2739 if (reg_set_p (reg, pat))
2741 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
2744 if (GET_CODE (pat) == PARALLEL)
2746 /* If we find a SET of something else, we can't
2751 for (i = 0; i < XVECLEN (pat, 0); i++)
2753 rtx part = XVECEXP (pat, 0, i);
2755 if (GET_CODE (part) == SET
2756 && SET_DEST (part) != reg)
2760 if (i == XVECLEN (pat, 0))
2761 delete_computation (our_prev);
2763 else if (GET_CODE (pat) == SET
2764 && GET_CODE (SET_DEST (pat)) == REG)
2766 int dest_regno = REGNO (SET_DEST (pat));
2769 + (dest_regno < FIRST_PSEUDO_REGISTER
2770 ? HARD_REGNO_NREGS (dest_regno,
2771 GET_MODE (SET_DEST (pat))) : 1));
2772 int regno = REGNO (reg);
2775 + (regno < FIRST_PSEUDO_REGISTER
2776 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1));
2778 if (dest_regno >= regno
2779 && dest_endregno <= endregno)
2780 delete_computation (our_prev);
2782 /* We may have a multi-word hard register and some, but not
2783 all, of the words of the register are needed in subsequent
2784 insns. Write REG_UNUSED notes for those parts that were not
2786 else if (dest_regno <= regno
2787 && dest_endregno >= endregno)
2791 REG_NOTES (our_prev)
2792 = gen_rtx_EXPR_LIST (REG_UNUSED, reg,
2793 REG_NOTES (our_prev));
2795 for (i = dest_regno; i < dest_endregno; i++)
2796 if (! find_regno_note (our_prev, REG_UNUSED, i))
2799 if (i == dest_endregno)
2800 delete_computation (our_prev);
2807 /* If PAT references the register that dies here, it is an
2808 additional use. Hence any prior SET isn't dead. However, this
2809 insn becomes the new place for the REG_DEAD note. */
2810 if (reg_overlap_mentioned_p (reg, pat))
2812 XEXP (note, 1) = REG_NOTES (our_prev);
2813 REG_NOTES (our_prev) = note;
2819 /* Delete INSN and recursively delete insns that compute values used only
2820 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2821 If we are running before flow.c, we need do nothing since flow.c will
2822 delete dead code. We also can't know if the registers being used are
2823 dead or not at this point.
2825 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2826 nothing other than set a register that dies in this insn, we can delete
2829 On machines with CC0, if CC0 is used in this insn, we may be able to
2830 delete the insn that set it. */
2833 delete_computation (insn)
2839 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
2841 rtx prev = prev_nonnote_insn (insn);
2842 /* We assume that at this stage
2843 CC's are always set explicitly
2844 and always immediately before the jump that
2845 will use them. So if the previous insn
2846 exists to set the CC's, delete it
2847 (unless it performs auto-increments, etc.). */
2848 if (prev && GET_CODE (prev) == INSN
2849 && sets_cc0_p (PATTERN (prev)))
2851 if (sets_cc0_p (PATTERN (prev)) > 0
2852 && ! side_effects_p (PATTERN (prev)))
2853 delete_computation (prev);
2855 /* Otherwise, show that cc0 won't be used. */
2856 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
2857 cc0_rtx, REG_NOTES (prev));
2862 for (note = REG_NOTES (insn); note; note = next)
2864 next = XEXP (note, 1);
2866 if (REG_NOTE_KIND (note) != REG_DEAD
2867 /* Verify that the REG_NOTE is legitimate. */
2868 || GET_CODE (XEXP (note, 0)) != REG)
2871 delete_prior_computation (note, insn);
2877 /* Delete insn INSN from the chain of insns and update label ref counts.
2878 May delete some following insns as a consequence; may even delete
2879 a label elsewhere and insns that follow it.
2881 Returns the first insn after INSN that was not deleted. */
2887 register rtx next = NEXT_INSN (insn);
2888 register rtx prev = PREV_INSN (insn);
2889 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
2890 register int dont_really_delete = 0;
2893 while (next && INSN_DELETED_P (next))
2894 next = NEXT_INSN (next);
2896 /* This insn is already deleted => return first following nondeleted. */
2897 if (INSN_DELETED_P (insn))
2901 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2903 /* Don't delete user-declared labels. When optimizing, convert them
2904 to special NOTEs instead. When not optimizing, leave them alone. */
2905 if (was_code_label && LABEL_NAME (insn) != 0)
2908 dont_really_delete = 1;
2909 else if (! dont_really_delete)
2911 const char *name = LABEL_NAME (insn);
2912 PUT_CODE (insn, NOTE);
2913 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
2914 NOTE_SOURCE_FILE (insn) = name;
2915 dont_really_delete = 1;
2919 /* Mark this insn as deleted. */
2920 INSN_DELETED_P (insn) = 1;
2922 /* If this is an unconditional jump, delete it from the jump chain. */
2923 if (simplejump_p (insn))
2924 delete_from_jump_chain (insn);
2926 /* If instruction is followed by a barrier,
2927 delete the barrier too. */
2929 if (next != 0 && GET_CODE (next) == BARRIER)
2931 INSN_DELETED_P (next) = 1;
2932 next = NEXT_INSN (next);
2935 /* Patch out INSN (and the barrier if any) */
2937 if (! dont_really_delete)
2941 NEXT_INSN (prev) = next;
2942 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
2943 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
2944 XVECLEN (PATTERN (prev), 0) - 1)) = next;
2949 PREV_INSN (next) = prev;
2950 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
2951 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
2954 if (prev && NEXT_INSN (prev) == 0)
2955 set_last_insn (prev);
2958 /* If deleting a jump, decrement the count of the label,
2959 and delete the label if it is now unused. */
2961 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
2963 rtx lab = JUMP_LABEL (insn), lab_next;
2965 if (--LABEL_NUSES (lab) == 0)
2967 /* This can delete NEXT or PREV,
2968 either directly if NEXT is JUMP_LABEL (INSN),
2969 or indirectly through more levels of jumps. */
2972 /* I feel a little doubtful about this loop,
2973 but I see no clean and sure alternative way
2974 to find the first insn after INSN that is not now deleted.
2975 I hope this works. */
2976 while (next && INSN_DELETED_P (next))
2977 next = NEXT_INSN (next);
2980 else if ((lab_next = next_nonnote_insn (lab)) != NULL
2981 && GET_CODE (lab_next) == JUMP_INSN
2982 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
2983 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
2985 /* If we're deleting the tablejump, delete the dispatch table.
2986 We may not be able to kill the label immediately preceeding
2987 just yet, as it might be referenced in code leading up to
2989 delete_insn (lab_next);
2993 /* Likewise if we're deleting a dispatch table. */
2995 if (GET_CODE (insn) == JUMP_INSN
2996 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2997 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2999 rtx pat = PATTERN (insn);
3000 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3001 int len = XVECLEN (pat, diff_vec_p);
3003 for (i = 0; i < len; i++)
3004 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3005 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3006 while (next && INSN_DELETED_P (next))
3007 next = NEXT_INSN (next);
3011 /* Likewise for an ordinary INSN / CALL_INSN with a REG_LABEL note. */
3012 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
3013 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
3014 if (REG_NOTE_KIND (note) == REG_LABEL
3015 /* This could also be a NOTE_INSN_DELETED_LABEL note. */
3016 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
3017 if (--LABEL_NUSES (XEXP (note, 0)) == 0)
3018 delete_insn (XEXP (note, 0));
3020 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3021 prev = PREV_INSN (prev);
3023 /* If INSN was a label and a dispatch table follows it,
3024 delete the dispatch table. The tablejump must have gone already.
3025 It isn't useful to fall through into a table. */
3028 && NEXT_INSN (insn) != 0
3029 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3030 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3031 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3032 next = delete_insn (NEXT_INSN (insn));
3034 /* If INSN was a label, delete insns following it if now unreachable. */
3036 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3038 register RTX_CODE code;
3040 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3041 || code == NOTE || code == BARRIER
3042 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3045 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3046 next = NEXT_INSN (next);
3047 /* Keep going past other deleted labels to delete what follows. */
3048 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3049 next = NEXT_INSN (next);
3051 /* Note: if this deletes a jump, it can cause more
3052 deletion of unreachable code, after a different label.
3053 As long as the value from this recursive call is correct,
3054 this invocation functions correctly. */
3055 next = delete_insn (next);
3062 /* Advance from INSN till reaching something not deleted
3063 then return that. May return INSN itself. */
3066 next_nondeleted_insn (insn)
3069 while (INSN_DELETED_P (insn))
3070 insn = NEXT_INSN (insn);
3074 /* Delete a range of insns from FROM to TO, inclusive.
3075 This is for the sake of peephole optimization, so assume
3076 that whatever these insns do will still be done by a new
3077 peephole insn that will replace them. */
3080 delete_for_peephole (from, to)
3081 register rtx from, to;
3083 register rtx insn = from;
3087 register rtx next = NEXT_INSN (insn);
3088 register rtx prev = PREV_INSN (insn);
3090 if (GET_CODE (insn) != NOTE)
3092 INSN_DELETED_P (insn) = 1;
3094 /* Patch this insn out of the chain. */
3095 /* We don't do this all at once, because we
3096 must preserve all NOTEs. */
3098 NEXT_INSN (prev) = next;
3101 PREV_INSN (next) = prev;
3109 /* Note that if TO is an unconditional jump
3110 we *do not* delete the BARRIER that follows,
3111 since the peephole that replaces this sequence
3112 is also an unconditional jump in that case. */
3115 /* We have determined that INSN is never reached, and are about to
3116 delete it. Print a warning if the user asked for one.
3118 To try to make this warning more useful, this should only be called
3119 once per basic block not reached, and it only warns when the basic
3120 block contains more than one line from the current function, and
3121 contains at least one operation. CSE and inlining can duplicate insns,
3122 so it's possible to get spurious warnings from this. */
3125 never_reached_warning (avoided_insn)
3129 rtx a_line_note = NULL;
3130 int two_avoided_lines = 0;
3131 int contains_insn = 0;
3133 if (! warn_notreached)
3136 /* Scan forwards, looking at LINE_NUMBER notes, until
3137 we hit a LABEL or we run out of insns. */
3139 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
3141 if (GET_CODE (insn) == CODE_LABEL)
3143 else if (GET_CODE (insn) == NOTE /* A line number note? */
3144 && NOTE_LINE_NUMBER (insn) >= 0)
3146 if (a_line_note == NULL)
3149 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
3150 != NOTE_LINE_NUMBER (insn));
3152 else if (INSN_P (insn))
3155 if (two_avoided_lines && contains_insn)
3156 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
3157 NOTE_LINE_NUMBER (a_line_note),
3158 "will never be executed");
3161 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
3162 NLABEL as a return. Accrue modifications into the change group. */
3165 redirect_exp_1 (loc, olabel, nlabel, insn)
3170 register rtx x = *loc;
3171 register RTX_CODE code = GET_CODE (x);
3173 register const char *fmt;
3175 if (code == LABEL_REF)
3177 if (XEXP (x, 0) == olabel)
3181 n = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3183 n = gen_rtx_RETURN (VOIDmode);
3185 validate_change (insn, loc, n, 1);
3189 else if (code == RETURN && olabel == 0)
3191 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3192 if (loc == &PATTERN (insn))
3193 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
3194 validate_change (insn, loc, x, 1);
3198 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3199 && GET_CODE (SET_SRC (x)) == LABEL_REF
3200 && XEXP (SET_SRC (x), 0) == olabel)
3202 validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 1);
3206 fmt = GET_RTX_FORMAT (code);
3207 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3210 redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
3211 else if (fmt[i] == 'E')
3214 for (j = 0; j < XVECLEN (x, i); j++)
3215 redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
3220 /* Similar, but apply the change group and report success or failure. */
3223 redirect_exp (olabel, nlabel, insn)
3229 if (GET_CODE (PATTERN (insn)) == PARALLEL)
3230 loc = &XVECEXP (PATTERN (insn), 0, 0);
3232 loc = &PATTERN (insn);
3234 redirect_exp_1 (loc, olabel, nlabel, insn);
3235 if (num_validated_changes () == 0)
3238 return apply_change_group ();
3241 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
3242 the modifications into the change group. Return false if we did
3243 not see how to do that. */
3246 redirect_jump_1 (jump, nlabel)
3249 int ochanges = num_validated_changes ();
3252 if (GET_CODE (PATTERN (jump)) == PARALLEL)
3253 loc = &XVECEXP (PATTERN (jump), 0, 0);
3255 loc = &PATTERN (jump);
3257 redirect_exp_1 (loc, JUMP_LABEL (jump), nlabel, jump);
3258 return num_validated_changes () > ochanges;
3261 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
3262 jump target label is unused as a result, it and the code following
3265 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3268 The return value will be 1 if the change was made, 0 if it wasn't
3269 (this can only occur for NLABEL == 0). */
3272 redirect_jump (jump, nlabel, delete_unused)
3276 register rtx olabel = JUMP_LABEL (jump);
3278 if (nlabel == olabel)
3281 if (! redirect_exp (olabel, nlabel, jump))
3284 /* If this is an unconditional branch, delete it from the jump_chain of
3285 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3286 have UID's in range and JUMP_CHAIN is valid). */
3287 if (jump_chain && (simplejump_p (jump)
3288 || GET_CODE (PATTERN (jump)) == RETURN))
3290 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3292 delete_from_jump_chain (jump);
3293 if (label_index < max_jump_chain
3294 && INSN_UID (jump) < max_jump_chain)
3296 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3297 jump_chain[label_index] = jump;
3301 JUMP_LABEL (jump) = nlabel;
3303 ++LABEL_NUSES (nlabel);
3305 /* If we're eliding the jump over exception cleanups at the end of a
3306 function, move the function end note so that -Wreturn-type works. */
3307 if (olabel && nlabel
3308 && NEXT_INSN (olabel)
3309 && GET_CODE (NEXT_INSN (olabel)) == NOTE
3310 && NOTE_LINE_NUMBER (NEXT_INSN (olabel)) == NOTE_INSN_FUNCTION_END)
3311 emit_note_after (NOTE_INSN_FUNCTION_END, nlabel);
3313 if (olabel && --LABEL_NUSES (olabel) == 0 && delete_unused)
3314 delete_insn (olabel);
3319 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3320 Accrue the modifications into the change group. */
3326 register RTX_CODE code;
3327 rtx x = pc_set (insn);
3333 code = GET_CODE (x);
3335 if (code == IF_THEN_ELSE)
3337 register rtx comp = XEXP (x, 0);
3339 enum rtx_code reversed_code;
3341 /* We can do this in two ways: The preferable way, which can only
3342 be done if this is not an integer comparison, is to reverse
3343 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3344 of the IF_THEN_ELSE. If we can't do either, fail. */
3346 reversed_code = reversed_comparison_code (comp, insn);
3348 if (reversed_code != UNKNOWN)
3350 validate_change (insn, &XEXP (x, 0),
3351 gen_rtx_fmt_ee (reversed_code,
3352 GET_MODE (comp), XEXP (comp, 0),
3359 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3360 validate_change (insn, &XEXP (x, 2), tem, 1);
3366 /* Invert the jump condition of conditional jump insn, INSN.
3368 Return 1 if we can do so, 0 if we cannot find a way to do so that
3369 matches a pattern. */
3375 invert_exp_1 (insn);
3376 if (num_validated_changes () == 0)
3379 return apply_change_group ();
3382 /* Invert the condition of the jump JUMP, and make it jump to label
3383 NLABEL instead of where it jumps now. Accrue changes into the
3384 change group. Return false if we didn't see how to perform the
3385 inversion and redirection. */
3388 invert_jump_1 (jump, nlabel)
3393 ochanges = num_validated_changes ();
3394 invert_exp_1 (jump);
3395 if (num_validated_changes () == ochanges)
3398 return redirect_jump_1 (jump, nlabel);
3401 /* Invert the condition of the jump JUMP, and make it jump to label
3402 NLABEL instead of where it jumps now. Return true if successful. */
3405 invert_jump (jump, nlabel, delete_unused)
3409 /* We have to either invert the condition and change the label or
3410 do neither. Either operation could fail. We first try to invert
3411 the jump. If that succeeds, we try changing the label. If that fails,
3412 we invert the jump back to what it was. */
3414 if (! invert_exp (jump))
3417 if (redirect_jump (jump, nlabel, delete_unused))
3419 /* An inverted jump means that a probability taken becomes a
3420 probability not taken. Subtract the branch probability from the
3421 probability base to convert it back to a taken probability. */
3423 rtx note = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3425 XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
3430 if (! invert_exp (jump))
3431 /* This should just be putting it back the way it was. */
3437 /* Delete the instruction JUMP from any jump chain it might be on. */
3440 delete_from_jump_chain (jump)
3444 rtx olabel = JUMP_LABEL (jump);
3446 /* Handle unconditional jumps. */
3447 if (jump_chain && olabel != 0
3448 && INSN_UID (olabel) < max_jump_chain
3449 && simplejump_p (jump))
3450 index = INSN_UID (olabel);
3451 /* Handle return insns. */
3452 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3457 if (jump_chain[index] == jump)
3458 jump_chain[index] = jump_chain[INSN_UID (jump)];
3463 for (insn = jump_chain[index];
3465 insn = jump_chain[INSN_UID (insn)])
3466 if (jump_chain[INSN_UID (insn)] == jump)
3468 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3474 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3476 If the old jump target label (before the dispatch table) becomes unused,
3477 it and the dispatch table may be deleted. In that case, find the insn
3478 before the jump references that label and delete it and logical successors
3482 redirect_tablejump (jump, nlabel)
3485 register rtx olabel = JUMP_LABEL (jump);
3486 rtx *notep, note, next;
3488 /* Add this jump to the jump_chain of NLABEL. */
3489 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3490 && INSN_UID (jump) < max_jump_chain)
3492 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3493 jump_chain[INSN_UID (nlabel)] = jump;
3496 for (notep = ®_NOTES (jump), note = *notep; note; note = next)
3498 next = XEXP (note, 1);
3500 if (REG_NOTE_KIND (note) != REG_DEAD
3501 /* Verify that the REG_NOTE is legitimate. */
3502 || GET_CODE (XEXP (note, 0)) != REG
3503 || ! reg_mentioned_p (XEXP (note, 0), PATTERN (jump)))
3504 notep = &XEXP (note, 1);
3507 delete_prior_computation (note, jump);
3512 PATTERN (jump) = gen_jump (nlabel);
3513 JUMP_LABEL (jump) = nlabel;
3514 ++LABEL_NUSES (nlabel);
3515 INSN_CODE (jump) = -1;
3517 if (--LABEL_NUSES (olabel) == 0)
3519 delete_labelref_insn (jump, olabel, 0);
3520 delete_insn (olabel);
3524 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3525 If we found one, delete it and then delete this insn if DELETE_THIS is
3526 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3529 delete_labelref_insn (insn, label, delete_this)
3536 if (GET_CODE (insn) != NOTE
3537 && reg_mentioned_p (label, PATTERN (insn)))
3548 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3549 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3563 /* Like rtx_equal_p except that it considers two REGs as equal
3564 if they renumber to the same value and considers two commutative
3565 operations to be the same if the order of the operands has been
3568 ??? Addition is not commutative on the PA due to the weird implicit
3569 space register selection rules for memory addresses. Therefore, we
3570 don't consider a + b == b + a.
3572 We could/should make this test a little tighter. Possibly only
3573 disabling it on the PA via some backend macro or only disabling this
3574 case when the PLUS is inside a MEM. */
3577 rtx_renumbered_equal_p (x, y)
3581 register RTX_CODE code = GET_CODE (x);
3582 register const char *fmt;
3587 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3588 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3589 && GET_CODE (SUBREG_REG (y)) == REG)))
3591 int reg_x = -1, reg_y = -1;
3592 int word_x = 0, word_y = 0;
3594 if (GET_MODE (x) != GET_MODE (y))
3597 /* If we haven't done any renumbering, don't
3598 make any assumptions. */
3599 if (reg_renumber == 0)
3600 return rtx_equal_p (x, y);
3604 reg_x = REGNO (SUBREG_REG (x));
3605 word_x = SUBREG_WORD (x);
3607 if (reg_renumber[reg_x] >= 0)
3609 reg_x = reg_renumber[reg_x] + word_x;
3617 if (reg_renumber[reg_x] >= 0)
3618 reg_x = reg_renumber[reg_x];
3621 if (GET_CODE (y) == SUBREG)
3623 reg_y = REGNO (SUBREG_REG (y));
3624 word_y = SUBREG_WORD (y);
3626 if (reg_renumber[reg_y] >= 0)
3628 reg_y = reg_renumber[reg_y];
3636 if (reg_renumber[reg_y] >= 0)
3637 reg_y = reg_renumber[reg_y];
3640 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3643 /* Now we have disposed of all the cases
3644 in which different rtx codes can match. */
3645 if (code != GET_CODE (y))
3657 return INTVAL (x) == INTVAL (y);
3660 /* We can't assume nonlocal labels have their following insns yet. */
3661 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3662 return XEXP (x, 0) == XEXP (y, 0);
3664 /* Two label-refs are equivalent if they point at labels
3665 in the same position in the instruction stream. */
3666 return (next_real_insn (XEXP (x, 0))
3667 == next_real_insn (XEXP (y, 0)));
3670 return XSTR (x, 0) == XSTR (y, 0);
3673 /* If we didn't match EQ equality above, they aren't the same. */
3680 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3682 if (GET_MODE (x) != GET_MODE (y))
3685 /* For commutative operations, the RTX match if the operand match in any
3686 order. Also handle the simple binary and unary cases without a loop.
3688 ??? Don't consider PLUS a commutative operator; see comments above. */
3689 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3691 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3692 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
3693 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
3694 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
3695 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3696 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3697 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
3698 else if (GET_RTX_CLASS (code) == '1')
3699 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
3701 /* Compare the elements. If any pair of corresponding elements
3702 fail to match, return 0 for the whole things. */
3704 fmt = GET_RTX_FORMAT (code);
3705 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3711 if (XWINT (x, i) != XWINT (y, i))
3716 if (XINT (x, i) != XINT (y, i))
3721 if (strcmp (XSTR (x, i), XSTR (y, i)))
3726 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3731 if (XEXP (x, i) != XEXP (y, i))
3738 if (XVECLEN (x, i) != XVECLEN (y, i))
3740 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3741 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3752 /* If X is a hard register or equivalent to one or a subregister of one,
3753 return the hard register number. If X is a pseudo register that was not
3754 assigned a hard register, return the pseudo register number. Otherwise,
3755 return -1. Any rtx is valid for X. */
3761 if (GET_CODE (x) == REG)
3763 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3764 return reg_renumber[REGNO (x)];
3767 if (GET_CODE (x) == SUBREG)
3769 int base = true_regnum (SUBREG_REG (x));
3770 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3771 return SUBREG_WORD (x) + base;
3776 /* Optimize code of the form:
3778 for (x = a[i]; x; ...)
3780 for (x = a[i]; x; ...)
3784 Loop optimize will change the above code into
3788 { ...; if (! (x = ...)) break; }
3791 { ...; if (! (x = ...)) break; }
3794 In general, if the first test fails, the program can branch
3795 directly to `foo' and skip the second try which is doomed to fail.
3796 We run this after loop optimization and before flow analysis. */
3798 /* When comparing the insn patterns, we track the fact that different
3799 pseudo-register numbers may have been used in each computation.
3800 The following array stores an equivalence -- same_regs[I] == J means
3801 that pseudo register I was used in the first set of tests in a context
3802 where J was used in the second set. We also count the number of such
3803 pending equivalences. If nonzero, the expressions really aren't the
3806 static int *same_regs;
3808 static int num_same_regs;
3810 /* Track any registers modified between the target of the first jump and
3811 the second jump. They never compare equal. */
3813 static char *modified_regs;
3815 /* Record if memory was modified. */
3817 static int modified_mem;
3819 /* Called via note_stores on each insn between the target of the first
3820 branch and the second branch. It marks any changed registers. */
3823 mark_modified_reg (dest, x, data)
3825 rtx x ATTRIBUTE_UNUSED;
3826 void *data ATTRIBUTE_UNUSED;
3831 if (GET_CODE (dest) == SUBREG)
3832 dest = SUBREG_REG (dest);
3834 if (GET_CODE (dest) == MEM)
3837 if (GET_CODE (dest) != REG)
3840 regno = REGNO (dest);
3841 if (regno >= FIRST_PSEUDO_REGISTER)
3842 modified_regs[regno] = 1;
3844 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3845 modified_regs[regno + i] = 1;
3848 /* F is the first insn in the chain of insns. */
3851 thread_jumps (f, max_reg, flag_before_loop)
3854 int flag_before_loop;
3856 /* Basic algorithm is to find a conditional branch,
3857 the label it may branch to, and the branch after
3858 that label. If the two branches test the same condition,
3859 walk back from both branch paths until the insn patterns
3860 differ, or code labels are hit. If we make it back to
3861 the target of the first branch, then we know that the first branch
3862 will either always succeed or always fail depending on the relative
3863 senses of the two branches. So adjust the first branch accordingly
3866 rtx label, b1, b2, t1, t2;
3867 enum rtx_code code1, code2;
3868 rtx b1op0, b1op1, b2op0, b2op1;
3872 enum rtx_code reversed_code1, reversed_code2;
3874 /* Allocate register tables and quick-reset table. */
3875 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
3876 same_regs = (int *) xmalloc (max_reg * sizeof (int));
3877 all_reset = (int *) xmalloc (max_reg * sizeof (int));
3878 for (i = 0; i < max_reg; i++)
3885 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3890 /* Get to a candidate branch insn. */
3891 if (GET_CODE (b1) != JUMP_INSN
3892 || ! any_condjump_p (b1) || JUMP_LABEL (b1) == 0)
3895 memset (modified_regs, 0, max_reg * sizeof (char));
3898 memcpy (same_regs, all_reset, max_reg * sizeof (int));
3901 label = JUMP_LABEL (b1);
3903 /* Look for a branch after the target. Record any registers and
3904 memory modified between the target and the branch. Stop when we
3905 get to a label since we can't know what was changed there. */
3906 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
3908 if (GET_CODE (b2) == CODE_LABEL)
3911 else if (GET_CODE (b2) == JUMP_INSN)
3913 /* If this is an unconditional jump and is the only use of
3914 its target label, we can follow it. */
3915 if (any_uncondjump_p (b2)
3917 && JUMP_LABEL (b2) != 0
3918 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
3920 b2 = JUMP_LABEL (b2);
3927 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
3930 if (GET_CODE (b2) == CALL_INSN)
3933 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3934 if (call_used_regs[i] && ! fixed_regs[i]
3935 && i != STACK_POINTER_REGNUM
3936 && i != FRAME_POINTER_REGNUM
3937 && i != HARD_FRAME_POINTER_REGNUM
3938 && i != ARG_POINTER_REGNUM)
3939 modified_regs[i] = 1;
3942 note_stores (PATTERN (b2), mark_modified_reg, NULL);
3945 /* Check the next candidate branch insn from the label
3948 || GET_CODE (b2) != JUMP_INSN
3950 || !any_condjump_p (b2)
3951 || !onlyjump_p (b2))
3956 /* Get the comparison codes and operands, reversing the
3957 codes if appropriate. If we don't have comparison codes,
3958 we can't do anything. */
3959 b1op0 = XEXP (XEXP (SET_SRC (set), 0), 0);
3960 b1op1 = XEXP (XEXP (SET_SRC (set), 0), 1);
3961 code1 = GET_CODE (XEXP (SET_SRC (set), 0));
3962 reversed_code1 = code1;
3963 if (XEXP (SET_SRC (set), 1) == pc_rtx)
3964 code1 = reversed_comparison_code (XEXP (SET_SRC (set), 0), b1);
3966 reversed_code1 = reversed_comparison_code (XEXP (SET_SRC (set), 0), b1);
3968 b2op0 = XEXP (XEXP (SET_SRC (set2), 0), 0);
3969 b2op1 = XEXP (XEXP (SET_SRC (set2), 0), 1);
3970 code2 = GET_CODE (XEXP (SET_SRC (set2), 0));
3971 reversed_code2 = code2;
3972 if (XEXP (SET_SRC (set2), 1) == pc_rtx)
3973 code2 = reversed_comparison_code (XEXP (SET_SRC (set2), 0), b2);
3975 reversed_code2 = reversed_comparison_code (XEXP (SET_SRC (set2), 0), b2);
3977 /* If they test the same things and knowing that B1 branches
3978 tells us whether or not B2 branches, check if we
3979 can thread the branch. */
3980 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
3981 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
3982 && (comparison_dominates_p (code1, code2)
3983 || comparison_dominates_p (code1, reversed_code2)))
3986 t1 = prev_nonnote_insn (b1);
3987 t2 = prev_nonnote_insn (b2);
3989 while (t1 != 0 && t2 != 0)
3993 /* We have reached the target of the first branch.
3994 If there are no pending register equivalents,
3995 we know that this branch will either always
3996 succeed (if the senses of the two branches are
3997 the same) or always fail (if not). */
4000 if (num_same_regs != 0)
4003 if (comparison_dominates_p (code1, code2))
4004 new_label = JUMP_LABEL (b2);
4006 new_label = get_label_after (b2);
4008 if (JUMP_LABEL (b1) != new_label)
4010 rtx prev = PREV_INSN (new_label);
4012 if (flag_before_loop
4013 && GET_CODE (prev) == NOTE
4014 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4016 /* Don't thread to the loop label. If a loop
4017 label is reused, loop optimization will
4018 be disabled for that loop. */
4019 new_label = gen_label_rtx ();
4020 emit_label_after (new_label, PREV_INSN (prev));
4022 changed |= redirect_jump (b1, new_label, 1);
4027 /* If either of these is not a normal insn (it might be
4028 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4029 have already been skipped above.) Similarly, fail
4030 if the insns are different. */
4031 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4032 || recog_memoized (t1) != recog_memoized (t2)
4033 || ! rtx_equal_for_thread_p (PATTERN (t1),
4037 t1 = prev_nonnote_insn (t1);
4038 t2 = prev_nonnote_insn (t2);
4045 free (modified_regs);
4050 /* This is like RTX_EQUAL_P except that it knows about our handling of
4051 possibly equivalent registers and knows to consider volatile and
4052 modified objects as not equal.
4054 YINSN is the insn containing Y. */
4057 rtx_equal_for_thread_p (x, y, yinsn)
4063 register enum rtx_code code;
4064 register const char *fmt;
4066 code = GET_CODE (x);
4067 /* Rtx's of different codes cannot be equal. */
4068 if (code != GET_CODE (y))
4071 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4072 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4074 if (GET_MODE (x) != GET_MODE (y))
4077 /* For floating-point, consider everything unequal. This is a bit
4078 pessimistic, but this pass would only rarely do anything for FP
4080 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4081 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
4084 /* For commutative operations, the RTX match if the operand match in any
4085 order. Also handle the simple binary and unary cases without a loop. */
4086 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4087 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4088 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4089 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4090 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4091 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4092 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4093 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4094 else if (GET_RTX_CLASS (code) == '1')
4095 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4097 /* Handle special-cases first. */
4101 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4104 /* If neither is user variable or hard register, check for possible
4106 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4107 || REGNO (x) < FIRST_PSEUDO_REGISTER
4108 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4111 if (same_regs[REGNO (x)] == -1)
4113 same_regs[REGNO (x)] = REGNO (y);
4116 /* If this is the first time we are seeing a register on the `Y'
4117 side, see if it is the last use. If not, we can't thread the
4118 jump, so mark it as not equivalent. */
4119 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4125 return (same_regs[REGNO (x)] == (int) REGNO (y));
4130 /* If memory modified or either volatile, not equivalent.
4131 Else, check address. */
4132 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4135 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4138 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4144 /* Cancel a pending `same_regs' if setting equivalenced registers.
4145 Then process source. */
4146 if (GET_CODE (SET_DEST (x)) == REG
4147 && GET_CODE (SET_DEST (y)) == REG)
4149 if (same_regs[REGNO (SET_DEST (x))] == (int) REGNO (SET_DEST (y)))
4151 same_regs[REGNO (SET_DEST (x))] = -1;
4154 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4159 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4163 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4166 return XEXP (x, 0) == XEXP (y, 0);
4169 return XSTR (x, 0) == XSTR (y, 0);
4178 fmt = GET_RTX_FORMAT (code);
4179 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4184 if (XWINT (x, i) != XWINT (y, i))
4190 if (XINT (x, i) != XINT (y, i))
4196 /* Two vectors must have the same length. */
4197 if (XVECLEN (x, i) != XVECLEN (y, i))
4200 /* And the corresponding elements must match. */
4201 for (j = 0; j < XVECLEN (x, i); j++)
4202 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4203 XVECEXP (y, i, j), yinsn) == 0)
4208 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4214 if (strcmp (XSTR (x, i), XSTR (y, i)))
4219 /* These are just backpointers, so they don't matter. */
4226 /* It is believed that rtx's at this level will never
4227 contain anything but integers and other rtx's,
4228 except for within LABEL_REFs and SYMBOL_REFs. */