1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997
3 1998, 1999, 2000 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. */
23 /* This is the jump-optimization pass of the compiler.
24 It is run two or three times: once before cse, sometimes once after cse,
25 and once after reload (before final).
27 jump_optimize deletes unreachable code and labels that are not used.
28 It also deletes jumps that jump to the following insn,
29 and simplifies jumps around unconditional jumps and jumps
30 to unconditional jumps.
32 Each CODE_LABEL has a count of the times it is used
33 stored in the LABEL_NUSES internal field, and each JUMP_INSN
34 has one label that it refers to stored in the
35 JUMP_LABEL internal field. With this we can detect labels that
36 become unused because of the deletion of all the jumps that
37 formerly used them. The JUMP_LABEL info is sometimes looked
40 Optionally, cross-jumping can be done. Currently it is done
41 only the last time (when after reload and before final).
42 In fact, the code for cross-jumping now assumes that register
43 allocation has been done, since it uses `rtx_renumbered_equal_p'.
45 Jump optimization is done after cse when cse's constant-propagation
46 causes jumps to become unconditional or to be deleted.
48 Unreachable loops are not detected here, because the labels
49 have references and the insns appear reachable from the labels.
50 find_basic_blocks in flow.c finds and deletes such loops.
52 The subroutines delete_insn, redirect_jump, and invert_jump are used
53 from other passes as well. */
60 #include "hard-reg-set.h"
62 #include "insn-config.h"
63 #include "insn-flags.h"
64 #include "insn-attr.h"
72 /* ??? Eventually must record somehow the labels used by jumps
73 from nested functions. */
74 /* Pre-record the next or previous real insn for each label?
75 No, this pass is very fast anyway. */
76 /* Condense consecutive labels?
77 This would make life analysis faster, maybe. */
78 /* Optimize jump y; x: ... y: jumpif... x?
79 Don't know if it is worth bothering with. */
80 /* Optimize two cases of conditional jump to conditional jump?
81 This can never delete any instruction or make anything dead,
82 or even change what is live at any point.
83 So perhaps let combiner do it. */
85 /* Vector indexed by uid.
86 For each CODE_LABEL, index by its uid to get first unconditional jump
87 that jumps to the label.
88 For each JUMP_INSN, index by its uid to get the next unconditional jump
89 that jumps to the same label.
90 Element 0 is the start of a chain of all return insns.
91 (It is safe to use element 0 because insn uid 0 is not used. */
93 static rtx *jump_chain;
95 /* Maximum index in jump_chain. */
97 static int max_jump_chain;
99 /* Set nonzero by jump_optimize if control can fall through
100 to the end of the function. */
103 /* Indicates whether death notes are significant in cross jump analysis.
104 Normally they are not significant, because of A and B jump to C,
105 and R dies in A, it must die in B. But this might not be true after
106 stack register conversion, and we must compare death notes in that
109 static int cross_jump_death_matters = 0;
111 static int init_label_info PARAMS ((rtx));
112 static void delete_barrier_successors PARAMS ((rtx));
113 static void mark_all_labels PARAMS ((rtx, int));
114 static rtx delete_unreferenced_labels PARAMS ((rtx));
115 static void delete_noop_moves PARAMS ((rtx));
116 static int calculate_can_reach_end PARAMS ((rtx, int));
117 static int duplicate_loop_exit_test PARAMS ((rtx));
118 static void find_cross_jump PARAMS ((rtx, rtx, int, rtx *, rtx *));
119 static void do_cross_jump PARAMS ((rtx, rtx, rtx));
120 static int jump_back_p PARAMS ((rtx, rtx));
121 static int tension_vector_labels PARAMS ((rtx, int));
122 static void mark_jump_label PARAMS ((rtx, rtx, int, int));
123 static void delete_computation PARAMS ((rtx));
124 static void redirect_exp_1 PARAMS ((rtx *, rtx, rtx, rtx));
125 static void invert_exp_1 PARAMS ((rtx, rtx));
126 static void delete_from_jump_chain PARAMS ((rtx));
127 static int delete_labelref_insn PARAMS ((rtx, rtx, int));
128 static void mark_modified_reg PARAMS ((rtx, rtx, void *));
129 static void redirect_tablejump PARAMS ((rtx, rtx));
130 static void jump_optimize_1 PARAMS ((rtx, int, int, int, int, int));
131 static int returnjump_p_1 PARAMS ((rtx *, void *));
132 static void delete_prior_computation PARAMS ((rtx, rtx));
134 /* Main external entry point into the jump optimizer. See comments before
135 jump_optimize_1 for descriptions of the arguments. */
137 jump_optimize (f, cross_jump, noop_moves, after_regscan)
143 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0, 0);
146 /* Alternate entry into the jump optimizer. This entry point only rebuilds
147 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
150 rebuild_jump_labels (f)
153 jump_optimize_1 (f, 0, 0, 0, 1, 0);
156 /* Alternate entry into the jump optimizer. Do only trivial optimizations. */
158 jump_optimize_minimal (f)
161 jump_optimize_1 (f, 0, 0, 0, 0, 1);
164 /* Delete no-op jumps and optimize jumps to jumps
165 and jumps around jumps.
166 Delete unused labels and unreachable code.
168 If CROSS_JUMP is 1, detect matching code
169 before a jump and its destination and unify them.
170 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
172 If NOOP_MOVES is nonzero, delete no-op move insns.
174 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
175 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
177 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
178 and JUMP_LABEL field for jumping insns.
180 If `optimize' is zero, don't change any code,
181 just determine whether control drops off the end of the function.
182 This case occurs when we have -W and not -O.
183 It works because `delete_insn' checks the value of `optimize'
184 and refrains from actually deleting when that is 0.
186 If MINIMAL is nonzero, then we only perform trivial optimizations:
188 * Removal of unreachable code after BARRIERs.
189 * Removal of unreferenced CODE_LABELs.
190 * Removal of a jump to the next instruction.
191 * Removal of a conditional jump followed by an unconditional jump
192 to the same target as the conditional jump.
193 * Simplify a conditional jump around an unconditional jump.
194 * Simplify a jump to a jump.
195 * Delete extraneous line number notes.
199 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan,
200 mark_labels_only, minimal)
205 int mark_labels_only;
208 register rtx insn, next;
215 cross_jump_death_matters = (cross_jump == 2);
216 max_uid = init_label_info (f) + 1;
218 /* If we are performing cross jump optimizations, then initialize
219 tables mapping UIDs to EH regions to avoid incorrect movement
220 of insns from one EH region to another. */
221 if (flag_exceptions && cross_jump)
222 init_insn_eh_region (f, max_uid);
224 if (! mark_labels_only)
225 delete_barrier_successors (f);
227 /* Leave some extra room for labels and duplicate exit test insns
229 max_jump_chain = max_uid * 14 / 10;
230 jump_chain = (rtx *) xcalloc (max_jump_chain, sizeof (rtx));
232 mark_all_labels (f, cross_jump);
234 /* Keep track of labels used from static data; we don't track them
235 closely enough to delete them here, so make sure their reference
236 count doesn't drop to zero. */
238 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
239 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
240 LABEL_NUSES (XEXP (insn, 0))++;
242 check_exception_handler_labels ();
244 /* Keep track of labels used for marking handlers for exception
245 regions; they cannot usually be deleted. */
247 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
248 LABEL_NUSES (XEXP (insn, 0))++;
250 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
251 notes and recompute LABEL_NUSES. */
252 if (mark_labels_only)
256 exception_optimize ();
258 last_insn = delete_unreferenced_labels (f);
261 delete_noop_moves (f);
263 /* If we haven't yet gotten to reload and we have just run regscan,
264 delete any insn that sets a register that isn't used elsewhere.
265 This helps some of the optimizations below by having less insns
266 being jumped around. */
268 if (optimize && ! reload_completed && after_regscan)
269 for (insn = f; insn; insn = next)
271 rtx set = single_set (insn);
273 next = NEXT_INSN (insn);
275 if (set && GET_CODE (SET_DEST (set)) == REG
276 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
277 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
278 /* We use regno_last_note_uid so as not to delete the setting
279 of a reg that's used in notes. A subsequent optimization
280 might arrange to use that reg for real. */
281 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
282 && ! side_effects_p (SET_SRC (set))
283 && ! find_reg_note (insn, REG_RETVAL, 0)
284 /* An ADDRESSOF expression can turn into a use of the internal arg
285 pointer, so do not delete the initialization of the internal
286 arg pointer yet. If it is truly dead, flow will delete the
287 initializing insn. */
288 && SET_DEST (set) != current_function_internal_arg_pointer)
292 /* Now iterate optimizing jumps until nothing changes over one pass. */
294 old_max_reg = max_reg_num ();
299 for (insn = f; insn; insn = next)
302 rtx temp, temp1, temp2 = NULL_RTX;
303 rtx temp4 ATTRIBUTE_UNUSED;
305 int this_is_simplejump, this_is_condjump;
306 int this_is_condjump_in_parallel;
308 next = NEXT_INSN (insn);
310 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
311 jump. Try to optimize by duplicating the loop exit test if so.
312 This is only safe immediately after regscan, because it uses
313 the values of regno_first_uid and regno_last_uid. */
314 if (after_regscan && GET_CODE (insn) == NOTE
315 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
316 && (temp1 = next_nonnote_insn (insn)) != 0
317 && simplejump_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_simplejump = simplejump_p (insn);
332 this_is_condjump = condjump_p (insn);
333 this_is_condjump_in_parallel = condjump_in_parallel_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 && this_is_condjump)
391 next = next_real_insn (JUMP_LABEL (insn));
394 /* Remove the "inactive" but "real" insns (i.e. uses and
395 clobbers) in between here and there. */
397 while ((temp = next_real_insn (temp)) != next)
404 /* Detect a conditional jump going to the same place
405 as an immediately following unconditional jump. */
406 else if (this_is_condjump
407 && (temp = next_active_insn (insn)) != 0
408 && simplejump_p (temp)
409 && (next_active_insn (JUMP_LABEL (insn))
410 == next_active_insn (JUMP_LABEL (temp))))
412 /* Don't mess up test coverage analysis. */
414 if (flag_test_coverage && !reload_completed)
415 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
416 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
427 /* Detect a conditional jump jumping over an unconditional jump. */
429 else if ((this_is_condjump || this_is_condjump_in_parallel)
430 && ! this_is_simplejump
431 && reallabelprev != 0
432 && GET_CODE (reallabelprev) == JUMP_INSN
433 && prev_active_insn (reallabelprev) == insn
434 && no_labels_between_p (insn, reallabelprev)
435 && simplejump_p (reallabelprev))
437 /* When we invert the unconditional jump, we will be
438 decrementing the usage count of its old label.
439 Make sure that we don't delete it now because that
440 might cause the following code to be deleted. */
441 rtx prev_uses = prev_nonnote_insn (reallabelprev);
442 rtx prev_label = JUMP_LABEL (insn);
445 ++LABEL_NUSES (prev_label);
447 if (invert_jump (insn, JUMP_LABEL (reallabelprev), 1))
449 /* It is very likely that if there are USE insns before
450 this jump, they hold REG_DEAD notes. These REG_DEAD
451 notes are no longer valid due to this optimization,
452 and will cause the life-analysis that following passes
453 (notably delayed-branch scheduling) to think that
454 these registers are dead when they are not.
456 To prevent this trouble, we just remove the USE insns
457 from the insn chain. */
459 while (prev_uses && GET_CODE (prev_uses) == INSN
460 && GET_CODE (PATTERN (prev_uses)) == USE)
462 rtx useless = prev_uses;
463 prev_uses = prev_nonnote_insn (prev_uses);
464 delete_insn (useless);
467 delete_insn (reallabelprev);
471 /* We can now safely delete the label if it is unreferenced
472 since the delete_insn above has deleted the BARRIER. */
473 if (prev_label && --LABEL_NUSES (prev_label) == 0)
474 delete_insn (prev_label);
476 next = NEXT_INSN (insn);
479 /* If we have an unconditional jump preceded by a USE, try to put
480 the USE before the target and jump there. This simplifies many
481 of the optimizations below since we don't have to worry about
482 dealing with these USE insns. We only do this if the label
483 being branch to already has the identical USE or if code
484 never falls through to that label. */
486 else if (this_is_simplejump
487 && (temp = prev_nonnote_insn (insn)) != 0
488 && GET_CODE (temp) == INSN
489 && GET_CODE (PATTERN (temp)) == USE
490 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
491 && (GET_CODE (temp1) == BARRIER
492 || (GET_CODE (temp1) == INSN
493 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
494 /* Don't do this optimization if we have a loop containing
495 only the USE instruction, and the loop start label has
496 a usage count of 1. This is because we will redo this
497 optimization everytime through the outer loop, and jump
498 opt will never exit. */
499 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
500 && temp2 == JUMP_LABEL (insn)
501 && LABEL_NUSES (temp2) == 1))
503 if (GET_CODE (temp1) == BARRIER)
505 emit_insn_after (PATTERN (temp), temp1);
506 temp1 = NEXT_INSN (temp1);
510 redirect_jump (insn, get_label_before (temp1), 1);
511 reallabelprev = prev_real_insn (temp1);
513 next = NEXT_INSN (insn);
517 /* Detect a conditional jump jumping over an unconditional trap. */
519 && this_is_condjump && ! this_is_simplejump
520 && reallabelprev != 0
521 && GET_CODE (reallabelprev) == INSN
522 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
523 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
524 && prev_active_insn (reallabelprev) == insn
525 && no_labels_between_p (insn, reallabelprev)
526 && (temp2 = get_condition (insn, &temp4))
527 && can_reverse_comparison_p (temp2, insn))
529 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
530 XEXP (temp2, 0), XEXP (temp2, 1),
531 TRAP_CODE (PATTERN (reallabelprev)));
535 emit_insn_before (new, temp4);
536 delete_insn (reallabelprev);
542 /* Detect a jump jumping to an unconditional trap. */
543 else if (HAVE_trap && this_is_condjump
544 && (temp = next_active_insn (JUMP_LABEL (insn)))
545 && GET_CODE (temp) == INSN
546 && GET_CODE (PATTERN (temp)) == TRAP_IF
547 && (this_is_simplejump
548 || (temp2 = get_condition (insn, &temp4))))
550 rtx tc = TRAP_CONDITION (PATTERN (temp));
552 if (tc == const_true_rtx
553 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
556 /* Replace an unconditional jump to a trap with a trap. */
557 if (this_is_simplejump)
559 emit_barrier_after (emit_insn_before (gen_trap (), insn));
564 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
566 TRAP_CODE (PATTERN (temp)));
569 emit_insn_before (new, temp4);
575 /* If the trap condition and jump condition are mutually
576 exclusive, redirect the jump to the following insn. */
577 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
578 && ! this_is_simplejump
579 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
580 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
581 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
582 && redirect_jump (insn, get_label_after (temp), 1))
591 /* Now that the jump has been tensioned,
592 try cross jumping: check for identical code
593 before the jump and before its target label. */
595 /* First, cross jumping of conditional jumps: */
597 if (cross_jump && condjump_p (insn))
599 rtx newjpos, newlpos;
600 rtx x = prev_real_insn (JUMP_LABEL (insn));
602 /* A conditional jump may be crossjumped
603 only if the place it jumps to follows
604 an opposing jump that comes back here. */
606 if (x != 0 && ! jump_back_p (x, insn))
607 /* We have no opposing jump;
608 cannot cross jump this insn. */
612 /* TARGET is nonzero if it is ok to cross jump
613 to code before TARGET. If so, see if matches. */
615 find_cross_jump (insn, x,
616 (optimize_size ? 1 : BRANCH_COST) + 1,
621 do_cross_jump (insn, newjpos, newlpos);
622 /* Make the old conditional jump
623 into an unconditional one. */
624 SET_SRC (PATTERN (insn))
625 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
626 INSN_CODE (insn) = -1;
627 emit_barrier_after (insn);
628 /* Add to jump_chain unless this is a new label
629 whose UID is too large. */
630 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
632 jump_chain[INSN_UID (insn)]
633 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
634 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
641 /* Cross jumping of unconditional jumps:
642 a few differences. */
644 if (cross_jump && simplejump_p (insn))
646 rtx newjpos, newlpos;
651 /* TARGET is nonzero if it is ok to cross jump
652 to code before TARGET. If so, see if matches. */
653 find_cross_jump (insn, JUMP_LABEL (insn),
654 optimize_size ? 1 : BRANCH_COST,
657 /* If cannot cross jump to code before the label,
658 see if we can cross jump to another jump to
660 /* Try each other jump to this label. */
661 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
662 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
663 target != 0 && newjpos == 0;
664 target = jump_chain[INSN_UID (target)])
666 && JUMP_LABEL (target) == JUMP_LABEL (insn)
667 /* Ignore TARGET if it's deleted. */
668 && ! INSN_DELETED_P (target))
669 find_cross_jump (insn, target,
670 (optimize_size ? 1 : BRANCH_COST) + 1,
675 do_cross_jump (insn, newjpos, newlpos);
681 /* This code was dead in the previous jump.c! */
682 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
684 /* Return insns all "jump to the same place"
685 so we can cross-jump between any two of them. */
687 rtx newjpos, newlpos, target;
691 /* If cannot cross jump to code before the label,
692 see if we can cross jump to another jump to
694 /* Try each other jump to this label. */
695 for (target = jump_chain[0];
696 target != 0 && newjpos == 0;
697 target = jump_chain[INSN_UID (target)])
699 && ! INSN_DELETED_P (target)
700 && GET_CODE (PATTERN (target)) == RETURN)
701 find_cross_jump (insn, target,
702 (optimize_size ? 1 : BRANCH_COST) + 1,
707 do_cross_jump (insn, newjpos, newlpos);
718 /* Delete extraneous line number notes.
719 Note that two consecutive notes for different lines are not really
720 extraneous. There should be some indication where that line belonged,
721 even if it became empty. */
726 for (insn = f; insn; insn = NEXT_INSN (insn))
727 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
729 /* Delete this note if it is identical to previous note. */
731 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
732 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
742 /* CAN_REACH_END is persistent for each function. Once set it should
743 not be cleared. This is especially true for the case where we
744 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
745 the front-end before compiling each function. */
746 if (! minimal && calculate_can_reach_end (last_insn, optimize != 0))
755 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
756 notes whose labels don't occur in the insn any more. Returns the
757 largest INSN_UID found. */
765 for (insn = f; insn; insn = NEXT_INSN (insn))
767 if (GET_CODE (insn) == CODE_LABEL)
768 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
769 else if (GET_CODE (insn) == JUMP_INSN)
770 JUMP_LABEL (insn) = 0;
771 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
775 for (note = REG_NOTES (insn); note; note = next)
777 next = XEXP (note, 1);
778 if (REG_NOTE_KIND (note) == REG_LABEL
779 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
780 remove_note (insn, note);
783 if (INSN_UID (insn) > largest_uid)
784 largest_uid = INSN_UID (insn);
790 /* Delete insns following barriers, up to next label.
792 Also delete no-op jumps created by gcse. */
795 delete_barrier_successors (f)
800 for (insn = f; insn;)
802 if (GET_CODE (insn) == BARRIER)
804 insn = NEXT_INSN (insn);
806 never_reached_warning (insn);
808 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
810 if (GET_CODE (insn) == NOTE
811 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
812 insn = NEXT_INSN (insn);
814 insn = delete_insn (insn);
816 /* INSN is now the code_label. */
819 /* Also remove (set (pc) (pc)) insns which can be created by
820 gcse. We eliminate such insns now to avoid having them
821 cause problems later. */
822 else if (GET_CODE (insn) == JUMP_INSN
823 && GET_CODE (PATTERN (insn)) == SET
824 && SET_SRC (PATTERN (insn)) == pc_rtx
825 && SET_DEST (PATTERN (insn)) == pc_rtx)
826 insn = delete_insn (insn);
829 insn = NEXT_INSN (insn);
833 /* Mark the label each jump jumps to.
834 Combine consecutive labels, and count uses of labels.
836 For each label, make a chain (using `jump_chain')
837 of all the *unconditional* jumps that jump to it;
838 also make a chain of all returns.
840 CROSS_JUMP indicates whether we are doing cross jumping
841 and if we are whether we will be paying attention to
842 death notes or not. */
845 mark_all_labels (f, cross_jump)
851 for (insn = f; insn; insn = NEXT_INSN (insn))
852 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
854 if (GET_CODE (insn) == CALL_INSN
855 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
857 mark_all_labels (XEXP (PATTERN (insn), 0), cross_jump);
858 mark_all_labels (XEXP (PATTERN (insn), 1), cross_jump);
859 mark_all_labels (XEXP (PATTERN (insn), 2), cross_jump);
863 mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
864 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
866 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
868 jump_chain[INSN_UID (insn)]
869 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
870 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
872 if (GET_CODE (PATTERN (insn)) == RETURN)
874 jump_chain[INSN_UID (insn)] = jump_chain[0];
875 jump_chain[0] = insn;
881 /* Delete all labels already not referenced.
882 Also find and return the last insn. */
885 delete_unreferenced_labels (f)
888 rtx final = NULL_RTX;
891 for (insn = f; insn; )
893 if (GET_CODE (insn) == CODE_LABEL
894 && LABEL_NUSES (insn) == 0
895 && LABEL_ALTERNATE_NAME (insn) == NULL)
896 insn = delete_insn (insn);
900 insn = NEXT_INSN (insn);
907 /* Delete various simple forms of moves which have no necessary
911 delete_noop_moves (f)
916 for (insn = f; insn; )
918 next = NEXT_INSN (insn);
920 if (GET_CODE (insn) == INSN)
922 register rtx body = PATTERN (insn);
924 /* Detect and delete no-op move instructions
925 resulting from not allocating a parameter in a register. */
927 if (GET_CODE (body) == SET
928 && (SET_DEST (body) == SET_SRC (body)
929 || (GET_CODE (SET_DEST (body)) == MEM
930 && GET_CODE (SET_SRC (body)) == MEM
931 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
932 && ! (GET_CODE (SET_DEST (body)) == MEM
933 && MEM_VOLATILE_P (SET_DEST (body)))
934 && ! (GET_CODE (SET_SRC (body)) == MEM
935 && MEM_VOLATILE_P (SET_SRC (body))))
936 delete_computation (insn);
938 /* Detect and ignore no-op move instructions
939 resulting from smart or fortuitous register allocation. */
941 else if (GET_CODE (body) == SET)
943 int sreg = true_regnum (SET_SRC (body));
944 int dreg = true_regnum (SET_DEST (body));
946 if (sreg == dreg && sreg >= 0)
948 else if (sreg >= 0 && dreg >= 0)
951 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
952 sreg, NULL_PTR, dreg,
953 GET_MODE (SET_SRC (body)));
956 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
958 /* DREG may have been the target of a REG_DEAD note in
959 the insn which makes INSN redundant. If so, reorg
960 would still think it is dead. So search for such a
961 note and delete it if we find it. */
962 if (! find_regno_note (insn, REG_UNUSED, dreg))
963 for (trial = prev_nonnote_insn (insn);
964 trial && GET_CODE (trial) != CODE_LABEL;
965 trial = prev_nonnote_insn (trial))
966 if (find_regno_note (trial, REG_DEAD, dreg))
968 remove_death (dreg, trial);
972 /* Deleting insn could lose a death-note for SREG. */
973 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
975 /* Change this into a USE so that we won't emit
976 code for it, but still can keep the note. */
978 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
979 INSN_CODE (insn) = -1;
980 /* Remove all reg notes but the REG_DEAD one. */
981 REG_NOTES (insn) = trial;
982 XEXP (trial, 1) = NULL_RTX;
988 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
989 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
991 GET_MODE (SET_DEST (body))))
993 /* This handles the case where we have two consecutive
994 assignments of the same constant to pseudos that didn't
995 get a hard reg. Each SET from the constant will be
996 converted into a SET of the spill register and an
997 output reload will be made following it. This produces
998 two loads of the same constant into the same spill
1003 /* Look back for a death note for the first reg.
1004 If there is one, it is no longer accurate. */
1005 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
1007 if ((GET_CODE (in_insn) == INSN
1008 || GET_CODE (in_insn) == JUMP_INSN)
1009 && find_regno_note (in_insn, REG_DEAD, dreg))
1011 remove_death (dreg, in_insn);
1014 in_insn = PREV_INSN (in_insn);
1017 /* Delete the second load of the value. */
1021 else if (GET_CODE (body) == PARALLEL)
1023 /* If each part is a set between two identical registers or
1024 a USE or CLOBBER, delete the insn. */
1028 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
1030 tem = XVECEXP (body, 0, i);
1031 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
1034 if (GET_CODE (tem) != SET
1035 || (sreg = true_regnum (SET_SRC (tem))) < 0
1036 || (dreg = true_regnum (SET_DEST (tem))) < 0
1044 /* Also delete insns to store bit fields if they are no-ops. */
1045 /* Not worth the hair to detect this in the big-endian case. */
1046 else if (! BYTES_BIG_ENDIAN
1047 && GET_CODE (body) == SET
1048 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
1049 && XEXP (SET_DEST (body), 2) == const0_rtx
1050 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
1051 && ! (GET_CODE (SET_SRC (body)) == MEM
1052 && MEM_VOLATILE_P (SET_SRC (body))))
1059 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1060 If so indicate that this function can drop off the end by returning
1063 CHECK_DELETED indicates whether we must check if the note being
1064 searched for has the deleted flag set.
1066 DELETE_FINAL_NOTE indicates whether we should delete the note
1070 calculate_can_reach_end (last, delete_final_note)
1072 int delete_final_note;
1077 while (insn != NULL_RTX)
1081 /* One label can follow the end-note: the return label. */
1082 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
1084 /* Ordinary insns can follow it if returning a structure. */
1085 else if (GET_CODE (insn) == INSN)
1087 /* If machine uses explicit RETURN insns, no epilogue,
1088 then one of them follows the note. */
1089 else if (GET_CODE (insn) == JUMP_INSN
1090 && GET_CODE (PATTERN (insn)) == RETURN)
1092 /* A barrier can follow the return insn. */
1093 else if (GET_CODE (insn) == BARRIER)
1095 /* Other kinds of notes can follow also. */
1096 else if (GET_CODE (insn) == NOTE
1097 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
1103 insn = PREV_INSN (insn);
1106 /* See if we backed up to the appropriate type of note. */
1107 if (insn != NULL_RTX
1108 && GET_CODE (insn) == NOTE
1109 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
1111 if (delete_final_note)
1119 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1120 jump. Assume that this unconditional jump is to the exit test code. If
1121 the code is sufficiently simple, make a copy of it before INSN,
1122 followed by a jump to the exit of the loop. Then delete the unconditional
1125 Return 1 if we made the change, else 0.
1127 This is only safe immediately after a regscan pass because it uses the
1128 values of regno_first_uid and regno_last_uid. */
1131 duplicate_loop_exit_test (loop_start)
1134 rtx insn, set, reg, p, link;
1135 rtx copy = 0, first_copy = 0;
1137 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
1139 int max_reg = max_reg_num ();
1142 /* Scan the exit code. We do not perform this optimization if any insn:
1146 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1147 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1148 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1151 We also do not do this if we find an insn with ASM_OPERANDS. While
1152 this restriction should not be necessary, copying an insn with
1153 ASM_OPERANDS can confuse asm_noperands in some cases.
1155 Also, don't do this if the exit code is more than 20 insns. */
1157 for (insn = exitcode;
1159 && ! (GET_CODE (insn) == NOTE
1160 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
1161 insn = NEXT_INSN (insn))
1163 switch (GET_CODE (insn))
1169 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
1170 a jump immediately after the loop start that branches outside
1171 the loop but within an outer loop, near the exit test.
1172 If we copied this exit test and created a phony
1173 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
1174 before the exit test look like these could be safely moved
1175 out of the loop even if they actually may be never executed.
1176 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
1178 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1179 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
1183 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1184 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
1185 /* If we were to duplicate this code, we would not move
1186 the BLOCK notes, and so debugging the moved code would
1187 be difficult. Thus, we only move the code with -O2 or
1194 /* The code below would grossly mishandle REG_WAS_0 notes,
1195 so get rid of them here. */
1196 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
1197 remove_note (insn, p);
1198 if (++num_insns > 20
1199 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1200 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
1208 /* Unless INSN is zero, we can do the optimization. */
1214 /* See if any insn sets a register only used in the loop exit code and
1215 not a user variable. If so, replace it with a new register. */
1216 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1217 if (GET_CODE (insn) == INSN
1218 && (set = single_set (insn)) != 0
1219 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
1220 || (GET_CODE (reg) == SUBREG
1221 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
1222 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
1223 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
1225 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
1226 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
1231 /* We can do the replacement. Allocate reg_map if this is the
1232 first replacement we found. */
1234 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
1236 REG_LOOP_TEST_P (reg) = 1;
1238 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
1242 /* Now copy each insn. */
1243 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1245 switch (GET_CODE (insn))
1248 copy = emit_barrier_before (loop_start);
1251 /* Only copy line-number notes. */
1252 if (NOTE_LINE_NUMBER (insn) >= 0)
1254 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
1255 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
1260 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
1262 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1264 mark_jump_label (PATTERN (copy), copy, 0, 0);
1266 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1268 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1269 if (REG_NOTE_KIND (link) != REG_LABEL)
1271 if (GET_CODE (link) == EXPR_LIST)
1273 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
1278 = copy_insn_1 (gen_rtx_INSN_LIST (REG_NOTE_KIND (link),
1283 if (reg_map && REG_NOTES (copy))
1284 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1288 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)), loop_start);
1290 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1291 mark_jump_label (PATTERN (copy), copy, 0, 0);
1292 if (REG_NOTES (insn))
1294 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
1296 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1299 /* If this is a simple jump, add it to the jump chain. */
1301 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
1302 && simplejump_p (copy))
1304 jump_chain[INSN_UID (copy)]
1305 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1306 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1314 /* Record the first insn we copied. We need it so that we can
1315 scan the copied insns for new pseudo registers. */
1320 /* Now clean up by emitting a jump to the end label and deleting the jump
1321 at the start of the loop. */
1322 if (! copy || GET_CODE (copy) != BARRIER)
1324 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
1327 /* Record the first insn we copied. We need it so that we can
1328 scan the copied insns for new pseudo registers. This may not
1329 be strictly necessary since we should have copied at least one
1330 insn above. But I am going to be safe. */
1334 mark_jump_label (PATTERN (copy), copy, 0, 0);
1335 if (INSN_UID (copy) < max_jump_chain
1336 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
1338 jump_chain[INSN_UID (copy)]
1339 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1340 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1342 emit_barrier_before (loop_start);
1345 /* Now scan from the first insn we copied to the last insn we copied
1346 (copy) for new pseudo registers. Do this after the code to jump to
1347 the end label since that might create a new pseudo too. */
1348 reg_scan_update (first_copy, copy, max_reg);
1350 /* Mark the exit code as the virtual top of the converted loop. */
1351 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
1353 delete_insn (next_nonnote_insn (loop_start));
1362 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
1363 eh-beg, eh-end notes between START and END out before START. Assume that
1364 END is not such a note. START may be such a note. Returns the value
1365 of the new starting insn, which may be different if the original start
1369 squeeze_notes (start, end)
1375 for (insn = start; insn != end; insn = next)
1377 next = NEXT_INSN (insn);
1378 if (GET_CODE (insn) == NOTE
1379 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
1380 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1381 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1382 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
1383 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
1384 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP
1385 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1386 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1392 rtx prev = PREV_INSN (insn);
1393 PREV_INSN (insn) = PREV_INSN (start);
1394 NEXT_INSN (insn) = start;
1395 NEXT_INSN (PREV_INSN (insn)) = insn;
1396 PREV_INSN (NEXT_INSN (insn)) = insn;
1397 NEXT_INSN (prev) = next;
1398 PREV_INSN (next) = prev;
1406 /* Compare the instructions before insn E1 with those before E2
1407 to find an opportunity for cross jumping.
1408 (This means detecting identical sequences of insns followed by
1409 jumps to the same place, or followed by a label and a jump
1410 to that label, and replacing one with a jump to the other.)
1412 Assume E1 is a jump that jumps to label E2
1413 (that is not always true but it might as well be).
1414 Find the longest possible equivalent sequences
1415 and store the first insns of those sequences into *F1 and *F2.
1416 Store zero there if no equivalent preceding instructions are found.
1418 We give up if we find a label in stream 1.
1419 Actually we could transfer that label into stream 2. */
1422 find_cross_jump (e1, e2, minimum, f1, f2)
1427 register rtx i1 = e1, i2 = e2;
1428 register rtx p1, p2;
1431 rtx last1 = 0, last2 = 0;
1432 rtx afterlast1 = 0, afterlast2 = 0;
1439 i1 = prev_nonnote_insn (i1);
1441 i2 = PREV_INSN (i2);
1442 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
1443 i2 = PREV_INSN (i2);
1448 /* Don't allow the range of insns preceding E1 or E2
1449 to include the other (E2 or E1). */
1450 if (i2 == e1 || i1 == e2)
1453 /* If we will get to this code by jumping, those jumps will be
1454 tensioned to go directly to the new label (before I2),
1455 so this cross-jumping won't cost extra. So reduce the minimum. */
1456 if (GET_CODE (i1) == CODE_LABEL)
1462 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
1465 /* Avoid moving insns across EH regions if either of the insns
1468 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
1469 && !in_same_eh_region (i1, i2))
1475 /* If this is a CALL_INSN, compare register usage information.
1476 If we don't check this on stack register machines, the two
1477 CALL_INSNs might be merged leaving reg-stack.c with mismatching
1478 numbers of stack registers in the same basic block.
1479 If we don't check this on machines with delay slots, a delay slot may
1480 be filled that clobbers a parameter expected by the subroutine.
1482 ??? We take the simple route for now and assume that if they're
1483 equal, they were constructed identically. */
1485 if (GET_CODE (i1) == CALL_INSN
1486 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1487 CALL_INSN_FUNCTION_USAGE (i2)))
1491 /* If cross_jump_death_matters is not 0, the insn's mode
1492 indicates whether or not the insn contains any stack-like
1495 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
1497 /* If register stack conversion has already been done, then
1498 death notes must also be compared before it is certain that
1499 the two instruction streams match. */
1502 HARD_REG_SET i1_regset, i2_regset;
1504 CLEAR_HARD_REG_SET (i1_regset);
1505 CLEAR_HARD_REG_SET (i2_regset);
1507 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
1508 if (REG_NOTE_KIND (note) == REG_DEAD
1509 && STACK_REG_P (XEXP (note, 0)))
1510 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
1512 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1513 if (REG_NOTE_KIND (note) == REG_DEAD
1514 && STACK_REG_P (XEXP (note, 0)))
1515 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1517 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
1526 /* Don't allow old-style asm or volatile extended asms to be accepted
1527 for cross jumping purposes. It is conceptually correct to allow
1528 them, since cross-jumping preserves the dynamic instruction order
1529 even though it is changing the static instruction order. However,
1530 if an asm is being used to emit an assembler pseudo-op, such as
1531 the MIPS `.set reorder' pseudo-op, then the static instruction order
1532 matters and it must be preserved. */
1533 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
1534 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
1535 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
1538 if (lose || GET_CODE (p1) != GET_CODE (p2)
1539 || ! rtx_renumbered_equal_p (p1, p2))
1541 /* The following code helps take care of G++ cleanups. */
1545 if (!lose && GET_CODE (p1) == GET_CODE (p2)
1546 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
1547 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
1548 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
1549 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
1550 /* If the equivalences are not to a constant, they may
1551 reference pseudos that no longer exist, so we can't
1553 && CONSTANT_P (XEXP (equiv1, 0))
1554 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1556 rtx s1 = single_set (i1);
1557 rtx s2 = single_set (i2);
1558 if (s1 != 0 && s2 != 0
1559 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
1561 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
1562 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
1563 if (! rtx_renumbered_equal_p (p1, p2))
1565 else if (apply_change_group ())
1570 /* Insns fail to match; cross jumping is limited to the following
1574 /* Don't allow the insn after a compare to be shared by
1575 cross-jumping unless the compare is also shared.
1576 Here, if either of these non-matching insns is a compare,
1577 exclude the following insn from possible cross-jumping. */
1578 if (sets_cc0_p (p1) || sets_cc0_p (p2))
1579 last1 = afterlast1, last2 = afterlast2, ++minimum;
1582 /* If cross-jumping here will feed a jump-around-jump
1583 optimization, this jump won't cost extra, so reduce
1585 if (GET_CODE (i1) == JUMP_INSN
1587 && prev_real_insn (JUMP_LABEL (i1)) == e1)
1593 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
1595 /* Ok, this insn is potentially includable in a cross-jump here. */
1596 afterlast1 = last1, afterlast2 = last2;
1597 last1 = i1, last2 = i2, --minimum;
1601 if (minimum <= 0 && last1 != 0 && last1 != e1)
1602 *f1 = last1, *f2 = last2;
1606 do_cross_jump (insn, newjpos, newlpos)
1607 rtx insn, newjpos, newlpos;
1609 /* Find an existing label at this point
1610 or make a new one if there is none. */
1611 register rtx label = get_label_before (newlpos);
1613 /* Make the same jump insn jump to the new point. */
1614 if (GET_CODE (PATTERN (insn)) == RETURN)
1616 /* Remove from jump chain of returns. */
1617 delete_from_jump_chain (insn);
1618 /* Change the insn. */
1619 PATTERN (insn) = gen_jump (label);
1620 INSN_CODE (insn) = -1;
1621 JUMP_LABEL (insn) = label;
1622 LABEL_NUSES (label)++;
1623 /* Add to new the jump chain. */
1624 if (INSN_UID (label) < max_jump_chain
1625 && INSN_UID (insn) < max_jump_chain)
1627 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
1628 jump_chain[INSN_UID (label)] = insn;
1632 redirect_jump (insn, label, 1);
1634 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
1635 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
1636 the NEWJPOS stream. */
1638 while (newjpos != insn)
1642 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
1643 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
1644 || REG_NOTE_KIND (lnote) == REG_EQUIV)
1645 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
1646 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
1647 remove_note (newlpos, lnote);
1649 delete_insn (newjpos);
1650 newjpos = next_real_insn (newjpos);
1651 newlpos = next_real_insn (newlpos);
1655 /* Return the label before INSN, or put a new label there. */
1658 get_label_before (insn)
1663 /* Find an existing label at this point
1664 or make a new one if there is none. */
1665 label = prev_nonnote_insn (insn);
1667 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1669 rtx prev = PREV_INSN (insn);
1671 label = gen_label_rtx ();
1672 emit_label_after (label, prev);
1673 LABEL_NUSES (label) = 0;
1678 /* Return the label after INSN, or put a new label there. */
1681 get_label_after (insn)
1686 /* Find an existing label at this point
1687 or make a new one if there is none. */
1688 label = next_nonnote_insn (insn);
1690 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1692 label = gen_label_rtx ();
1693 emit_label_after (label, insn);
1694 LABEL_NUSES (label) = 0;
1699 /* Return 1 if INSN is a jump that jumps to right after TARGET
1700 only on the condition that TARGET itself would drop through.
1701 Assumes that TARGET is a conditional jump. */
1704 jump_back_p (insn, target)
1708 enum rtx_code codei, codet;
1710 if (simplejump_p (insn) || ! condjump_p (insn)
1711 || simplejump_p (target)
1712 || target != prev_real_insn (JUMP_LABEL (insn)))
1715 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
1716 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
1718 codei = GET_CODE (cinsn);
1719 codet = GET_CODE (ctarget);
1721 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
1723 if (! can_reverse_comparison_p (cinsn, insn))
1725 codei = reverse_condition (codei);
1728 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
1730 if (! can_reverse_comparison_p (ctarget, target))
1732 codet = reverse_condition (codet);
1735 return (codei == codet
1736 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
1737 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
1740 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
1741 return non-zero if it is safe to reverse this comparison. It is if our
1742 floating-point is not IEEE, if this is an NE or EQ comparison, or if
1743 this is known to be an integer comparison. */
1746 can_reverse_comparison_p (comparison, insn)
1752 /* If this is not actually a comparison, we can't reverse it. */
1753 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
1756 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
1757 /* If this is an NE comparison, it is safe to reverse it to an EQ
1758 comparison and vice versa, even for floating point. If no operands
1759 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
1760 always false and NE is always true, so the reversal is also valid. */
1762 || GET_CODE (comparison) == NE
1763 || GET_CODE (comparison) == EQ)
1766 arg0 = XEXP (comparison, 0);
1768 /* Make sure ARG0 is one of the actual objects being compared. If we
1769 can't do this, we can't be sure the comparison can be reversed.
1771 Handle cc0 and a MODE_CC register. */
1772 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
1778 rtx prev = prev_nonnote_insn (insn);
1781 /* First see if the condition code mode alone if enough to say we can
1782 reverse the condition. If not, then search backwards for a set of
1783 ARG0. We do not need to check for an insn clobbering it since valid
1784 code will contain set a set with no intervening clobber. But
1785 stop when we reach a label. */
1786 #ifdef REVERSIBLE_CC_MODE
1787 if (GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC
1788 && REVERSIBLE_CC_MODE (GET_MODE (arg0)))
1792 for (prev = prev_nonnote_insn (insn);
1793 prev != 0 && GET_CODE (prev) != CODE_LABEL;
1794 prev = prev_nonnote_insn (prev))
1795 if ((set = single_set (prev)) != 0
1796 && rtx_equal_p (SET_DEST (set), arg0))
1798 arg0 = SET_SRC (set);
1800 if (GET_CODE (arg0) == COMPARE)
1801 arg0 = XEXP (arg0, 0);
1806 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
1807 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
1808 return (GET_CODE (arg0) == CONST_INT
1809 || (GET_MODE (arg0) != VOIDmode
1810 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
1811 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
1814 /* Given an rtx-code for a comparison, return the code for the negated
1815 comparison. If no such code exists, return UNKNOWN.
1817 WATCH OUT! reverse_condition is not safe to use on a jump that might
1818 be acting on the results of an IEEE floating point comparison, because
1819 of the special treatment of non-signaling nans in comparisons.
1820 Use can_reverse_comparison_p to be sure. */
1823 reverse_condition (code)
1866 /* Similar, but we're allowed to generate unordered comparisons, which
1867 makes it safe for IEEE floating-point. Of course, we have to recognize
1868 that the target will support them too... */
1871 reverse_condition_maybe_unordered (code)
1874 /* Non-IEEE formats don't have unordered conditions. */
1875 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
1876 return reverse_condition (code);
1922 /* Similar, but return the code when two operands of a comparison are swapped.
1923 This IS safe for IEEE floating-point. */
1926 swap_condition (code)
1969 /* Given a comparison CODE, return the corresponding unsigned comparison.
1970 If CODE is an equality comparison or already an unsigned comparison,
1971 CODE is returned. */
1974 unsigned_condition (code)
2001 /* Similarly, return the signed version of a comparison. */
2004 signed_condition (code)
2031 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2032 truth of CODE1 implies the truth of CODE2. */
2035 comparison_dominates_p (code1, code2)
2036 enum rtx_code code1, code2;
2044 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
2045 || code2 == ORDERED)
2050 if (code2 == LE || code2 == NE || code2 == ORDERED)
2055 if (code2 == GE || code2 == NE || code2 == ORDERED)
2061 if (code2 == ORDERED)
2066 if (code2 == NE || code2 == ORDERED)
2071 if (code2 == LEU || code2 == NE)
2076 if (code2 == GEU || code2 == NE)
2092 /* Return 1 if INSN is an unconditional jump and nothing else. */
2098 return (GET_CODE (insn) == JUMP_INSN
2099 && GET_CODE (PATTERN (insn)) == SET
2100 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2101 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2104 /* Return nonzero if INSN is a (possibly) conditional jump
2107 Use this function is deprecated, since we need to support combined
2108 branch and compare insns. Use any_condjump_p instead whenever possible. */
2114 register rtx x = PATTERN (insn);
2116 if (GET_CODE (x) != SET
2117 || GET_CODE (SET_DEST (x)) != PC)
2121 if (GET_CODE (x) == LABEL_REF)
2123 else return (GET_CODE (x) == IF_THEN_ELSE
2124 && ((GET_CODE (XEXP (x, 2)) == PC
2125 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
2126 || GET_CODE (XEXP (x, 1)) == RETURN))
2127 || (GET_CODE (XEXP (x, 1)) == PC
2128 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
2129 || GET_CODE (XEXP (x, 2)) == RETURN))));
2134 /* Return nonzero if INSN is a (possibly) conditional jump inside a
2137 Use this function is deprecated, since we need to support combined
2138 branch and compare insns. Use any_condjump_p instead whenever possible. */
2141 condjump_in_parallel_p (insn)
2144 register rtx x = PATTERN (insn);
2146 if (GET_CODE (x) != PARALLEL)
2149 x = XVECEXP (x, 0, 0);
2151 if (GET_CODE (x) != SET)
2153 if (GET_CODE (SET_DEST (x)) != PC)
2155 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2157 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2159 if (XEXP (SET_SRC (x), 2) == pc_rtx
2160 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2161 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2163 if (XEXP (SET_SRC (x), 1) == pc_rtx
2164 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2165 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2170 /* Return set of PC, otherwise NULL. */
2177 if (GET_CODE (insn) != JUMP_INSN)
2179 pat = PATTERN (insn);
2181 /* The set is allowed to appear either as the insn pattern or
2182 the first set in a PARALLEL. */
2183 if (GET_CODE (pat) == PARALLEL)
2184 pat = XVECEXP (pat, 0, 0);
2185 if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
2191 /* Return true when insn is an unconditional direct jump,
2192 possibly bundled inside a PARALLEL. */
2195 any_uncondjump_p (insn)
2198 rtx x = pc_set (insn);
2201 if (GET_CODE (SET_SRC (x)) != LABEL_REF)
2206 /* Return true when insn is a conditional jump. This function works for
2207 instructions containing PC sets in PARALLELs. The instruction may have
2208 various other effects so before removing the jump you must verify
2209 safe_to_remove_jump_p.
2211 Note that unlike condjump_p it returns false for unconditional jumps. */
2214 any_condjump_p (insn)
2217 rtx x = pc_set (insn);
2222 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2225 a = GET_CODE (XEXP (SET_SRC (x), 1));
2226 b = GET_CODE (XEXP (SET_SRC (x), 2));
2228 return ((b == PC && (a == LABEL_REF || a == RETURN))
2229 || (a == PC && (b == LABEL_REF || b == RETURN)));
2232 /* Return the label of a conditional jump. */
2235 condjump_label (insn)
2238 rtx x = pc_set (insn);
2243 if (GET_CODE (x) == LABEL_REF)
2245 if (GET_CODE (x) != IF_THEN_ELSE)
2247 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
2249 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
2254 /* Return true if INSN is a (possibly conditional) return insn. */
2257 returnjump_p_1 (loc, data)
2259 void *data ATTRIBUTE_UNUSED;
2262 return x && GET_CODE (x) == RETURN;
2269 if (GET_CODE (insn) != JUMP_INSN)
2271 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
2274 /* Return true if INSN is a jump that only transfers control and
2283 if (GET_CODE (insn) != JUMP_INSN)
2286 set = single_set (insn);
2289 if (GET_CODE (SET_DEST (set)) != PC)
2291 if (side_effects_p (SET_SRC (set)))
2299 /* Return 1 if X is an RTX that does nothing but set the condition codes
2300 and CLOBBER or USE registers.
2301 Return -1 if X does explicitly set the condition codes,
2302 but also does other things. */
2306 rtx x ATTRIBUTE_UNUSED;
2308 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2310 if (GET_CODE (x) == PARALLEL)
2314 int other_things = 0;
2315 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2317 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2318 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2320 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2323 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2329 /* Follow any unconditional jump at LABEL;
2330 return the ultimate label reached by any such chain of jumps.
2331 If LABEL is not followed by a jump, return LABEL.
2332 If the chain loops or we can't find end, return LABEL,
2333 since that tells caller to avoid changing the insn.
2335 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2336 a USE or CLOBBER. */
2339 follow_jumps (label)
2344 register rtx value = label;
2349 && (insn = next_active_insn (value)) != 0
2350 && GET_CODE (insn) == JUMP_INSN
2351 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2352 || GET_CODE (PATTERN (insn)) == RETURN)
2353 && (next = NEXT_INSN (insn))
2354 && GET_CODE (next) == BARRIER);
2357 /* Don't chain through the insn that jumps into a loop
2358 from outside the loop,
2359 since that would create multiple loop entry jumps
2360 and prevent loop optimization. */
2362 if (!reload_completed)
2363 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2364 if (GET_CODE (tem) == NOTE
2365 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
2366 /* ??? Optional. Disables some optimizations, but makes
2367 gcov output more accurate with -O. */
2368 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
2371 /* If we have found a cycle, make the insn jump to itself. */
2372 if (JUMP_LABEL (insn) == label)
2375 tem = next_active_insn (JUMP_LABEL (insn));
2376 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
2377 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
2380 value = JUMP_LABEL (insn);
2387 /* Assuming that field IDX of X is a vector of label_refs,
2388 replace each of them by the ultimate label reached by it.
2389 Return nonzero if a change is made.
2390 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2393 tension_vector_labels (x, idx)
2399 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2401 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2402 register rtx nlabel = follow_jumps (olabel);
2403 if (nlabel && nlabel != olabel)
2405 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2406 ++LABEL_NUSES (nlabel);
2407 if (--LABEL_NUSES (olabel) == 0)
2408 delete_insn (olabel);
2415 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2416 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2417 in INSN, then store one of them in JUMP_LABEL (INSN).
2418 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2419 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2420 Also, when there are consecutive labels, canonicalize on the last of them.
2422 Note that two labels separated by a loop-beginning note
2423 must be kept distinct if we have not yet done loop-optimization,
2424 because the gap between them is where loop-optimize
2425 will want to move invariant code to. CROSS_JUMP tells us
2426 that loop-optimization is done with.
2428 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2429 two labels distinct if they are separated by only USE or CLOBBER insns. */
2432 mark_jump_label (x, insn, cross_jump, in_mem)
2438 register RTX_CODE code = GET_CODE (x);
2440 register const char *fmt;
2462 /* If this is a constant-pool reference, see if it is a label. */
2463 if (CONSTANT_POOL_ADDRESS_P (x))
2464 mark_jump_label (get_pool_constant (x), insn, cross_jump, in_mem);
2469 rtx label = XEXP (x, 0);
2474 /* Ignore remaining references to unreachable labels that
2475 have been deleted. */
2476 if (GET_CODE (label) == NOTE
2477 && NOTE_LINE_NUMBER (label) == NOTE_INSN_DELETED_LABEL)
2480 if (GET_CODE (label) != CODE_LABEL)
2483 /* Ignore references to labels of containing functions. */
2484 if (LABEL_REF_NONLOCAL_P (x))
2487 /* If there are other labels following this one,
2488 replace it with the last of the consecutive labels. */
2489 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
2491 if (GET_CODE (next) == CODE_LABEL)
2493 else if (cross_jump && GET_CODE (next) == INSN
2494 && (GET_CODE (PATTERN (next)) == USE
2495 || GET_CODE (PATTERN (next)) == CLOBBER))
2497 else if (GET_CODE (next) != NOTE)
2499 else if (! cross_jump
2500 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
2501 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
2502 /* ??? Optional. Disables some optimizations, but
2503 makes gcov output more accurate with -O. */
2504 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
2508 XEXP (x, 0) = label;
2509 if (! insn || ! INSN_DELETED_P (insn))
2510 ++LABEL_NUSES (label);
2514 if (GET_CODE (insn) == JUMP_INSN)
2515 JUMP_LABEL (insn) = label;
2517 /* If we've changed OLABEL and we had a REG_LABEL note
2518 for it, update it as well. */
2519 else if (label != olabel
2520 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
2521 XEXP (note, 0) = label;
2523 /* Otherwise, add a REG_LABEL note for LABEL unless there already
2525 else if (! find_reg_note (insn, REG_LABEL, label))
2527 /* This code used to ignore labels which refered to dispatch
2528 tables to avoid flow.c generating worse code.
2530 However, in the presense of global optimizations like
2531 gcse which call find_basic_blocks without calling
2532 life_analysis, not recording such labels will lead
2533 to compiler aborts because of inconsistencies in the
2534 flow graph. So we go ahead and record the label.
2536 It may also be the case that the optimization argument
2537 is no longer valid because of the more accurate cfg
2538 we build in find_basic_blocks -- it no longer pessimizes
2539 code when it finds a REG_LABEL note. */
2540 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
2547 /* Do walk the labels in a vector, but not the first operand of an
2548 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2551 if (! INSN_DELETED_P (insn))
2553 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
2555 for (i = 0; i < XVECLEN (x, eltnum); i++)
2556 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX,
2557 cross_jump, in_mem);
2565 fmt = GET_RTX_FORMAT (code);
2566 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2569 mark_jump_label (XEXP (x, i), insn, cross_jump, in_mem);
2570 else if (fmt[i] == 'E')
2573 for (j = 0; j < XVECLEN (x, i); j++)
2574 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump, in_mem);
2579 /* If all INSN does is set the pc, delete it,
2580 and delete the insn that set the condition codes for it
2581 if that's what the previous thing was. */
2587 register rtx set = single_set (insn);
2589 if (set && GET_CODE (SET_DEST (set)) == PC)
2590 delete_computation (insn);
2593 /* Verify INSN is a BARRIER and delete it. */
2596 delete_barrier (insn)
2599 if (GET_CODE (insn) != BARRIER)
2605 /* Recursively delete prior insns that compute the value (used only by INSN
2606 which the caller is deleting) stored in the register mentioned by NOTE
2607 which is a REG_DEAD note associated with INSN. */
2610 delete_prior_computation (note, insn)
2615 rtx reg = XEXP (note, 0);
2617 for (our_prev = prev_nonnote_insn (insn);
2618 our_prev && (GET_CODE (our_prev) == INSN
2619 || GET_CODE (our_prev) == CALL_INSN);
2620 our_prev = prev_nonnote_insn (our_prev))
2622 rtx pat = PATTERN (our_prev);
2624 /* If we reach a CALL which is not calling a const function
2625 or the callee pops the arguments, then give up. */
2626 if (GET_CODE (our_prev) == CALL_INSN
2627 && (! CONST_CALL_P (our_prev)
2628 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
2631 /* If we reach a SEQUENCE, it is too complex to try to
2632 do anything with it, so give up. */
2633 if (GET_CODE (pat) == SEQUENCE)
2636 if (GET_CODE (pat) == USE
2637 && GET_CODE (XEXP (pat, 0)) == INSN)
2638 /* reorg creates USEs that look like this. We leave them
2639 alone because reorg needs them for its own purposes. */
2642 if (reg_set_p (reg, pat))
2644 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
2647 if (GET_CODE (pat) == PARALLEL)
2649 /* If we find a SET of something else, we can't
2654 for (i = 0; i < XVECLEN (pat, 0); i++)
2656 rtx part = XVECEXP (pat, 0, i);
2658 if (GET_CODE (part) == SET
2659 && SET_DEST (part) != reg)
2663 if (i == XVECLEN (pat, 0))
2664 delete_computation (our_prev);
2666 else if (GET_CODE (pat) == SET
2667 && GET_CODE (SET_DEST (pat)) == REG)
2669 int dest_regno = REGNO (SET_DEST (pat));
2671 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
2672 ? HARD_REGNO_NREGS (dest_regno,
2673 GET_MODE (SET_DEST (pat))) : 1);
2674 int regno = REGNO (reg);
2675 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
2676 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
2678 if (dest_regno >= regno
2679 && dest_endregno <= endregno)
2680 delete_computation (our_prev);
2682 /* We may have a multi-word hard register and some, but not
2683 all, of the words of the register are needed in subsequent
2684 insns. Write REG_UNUSED notes for those parts that were not
2686 else if (dest_regno <= regno
2687 && dest_endregno >= endregno)
2691 REG_NOTES (our_prev)
2692 = gen_rtx_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (our_prev));
2694 for (i = dest_regno; i < dest_endregno; i++)
2695 if (! find_regno_note (our_prev, REG_UNUSED, i))
2698 if (i == dest_endregno)
2699 delete_computation (our_prev);
2706 /* If PAT references the register that dies here, it is an
2707 additional use. Hence any prior SET isn't dead. However, this
2708 insn becomes the new place for the REG_DEAD note. */
2709 if (reg_overlap_mentioned_p (reg, pat))
2711 XEXP (note, 1) = REG_NOTES (our_prev);
2712 REG_NOTES (our_prev) = note;
2718 /* Delete INSN and recursively delete insns that compute values used only
2719 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2720 If we are running before flow.c, we need do nothing since flow.c will
2721 delete dead code. We also can't know if the registers being used are
2722 dead or not at this point.
2724 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2725 nothing other than set a register that dies in this insn, we can delete
2728 On machines with CC0, if CC0 is used in this insn, we may be able to
2729 delete the insn that set it. */
2732 delete_computation (insn)
2739 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
2741 rtx prev = prev_nonnote_insn (insn);
2742 /* We assume that at this stage
2743 CC's are always set explicitly
2744 and always immediately before the jump that
2745 will use them. So if the previous insn
2746 exists to set the CC's, delete it
2747 (unless it performs auto-increments, etc.). */
2748 if (prev && GET_CODE (prev) == INSN
2749 && sets_cc0_p (PATTERN (prev)))
2751 if (sets_cc0_p (PATTERN (prev)) > 0
2752 && ! side_effects_p (PATTERN (prev)))
2753 delete_computation (prev);
2755 /* Otherwise, show that cc0 won't be used. */
2756 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
2757 cc0_rtx, REG_NOTES (prev));
2762 #ifdef INSN_SCHEDULING
2763 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
2764 reload has completed. The schedulers need to be fixed. Until
2765 they are, we must not rely on the death notes here. */
2766 if (reload_completed && flag_schedule_insns_after_reload)
2773 /* The REG_DEAD note may have been omitted for a register
2774 which is both set and used by the insn. */
2775 set = single_set (insn);
2776 if (set && GET_CODE (SET_DEST (set)) == REG)
2778 int dest_regno = REGNO (SET_DEST (set));
2780 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
2781 ? HARD_REGNO_NREGS (dest_regno,
2782 GET_MODE (SET_DEST (set))) : 1);
2785 for (i = dest_regno; i < dest_endregno; i++)
2787 if (! refers_to_regno_p (i, i + 1, SET_SRC (set), NULL_PTR)
2788 || find_regno_note (insn, REG_DEAD, i))
2791 note = gen_rtx_EXPR_LIST (REG_DEAD, (i < FIRST_PSEUDO_REGISTER
2792 ? gen_rtx_REG (reg_raw_mode[i], i)
2793 : SET_DEST (set)), NULL_RTX);
2794 delete_prior_computation (note, insn);
2798 for (note = REG_NOTES (insn); note; note = next)
2800 next = XEXP (note, 1);
2802 if (REG_NOTE_KIND (note) != REG_DEAD
2803 /* Verify that the REG_NOTE is legitimate. */
2804 || GET_CODE (XEXP (note, 0)) != REG)
2807 delete_prior_computation (note, insn);
2813 /* Delete insn INSN from the chain of insns and update label ref counts.
2814 May delete some following insns as a consequence; may even delete
2815 a label elsewhere and insns that follow it.
2817 Returns the first insn after INSN that was not deleted. */
2823 register rtx next = NEXT_INSN (insn);
2824 register rtx prev = PREV_INSN (insn);
2825 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
2826 register int dont_really_delete = 0;
2828 while (next && INSN_DELETED_P (next))
2829 next = NEXT_INSN (next);
2831 /* This insn is already deleted => return first following nondeleted. */
2832 if (INSN_DELETED_P (insn))
2836 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2838 /* Don't delete user-declared labels. When optimizing, convert them
2839 to special NOTEs instead. When not optimizing, leave them alone. */
2840 if (was_code_label && LABEL_NAME (insn) != 0)
2843 dont_really_delete = 1;
2844 else if (! dont_really_delete)
2846 const char *name = LABEL_NAME (insn);
2847 PUT_CODE (insn, NOTE);
2848 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
2849 NOTE_SOURCE_FILE (insn) = name;
2850 dont_really_delete = 1;
2854 /* Mark this insn as deleted. */
2855 INSN_DELETED_P (insn) = 1;
2857 /* If this is an unconditional jump, delete it from the jump chain. */
2858 if (simplejump_p (insn))
2859 delete_from_jump_chain (insn);
2861 /* If instruction is followed by a barrier,
2862 delete the barrier too. */
2864 if (next != 0 && GET_CODE (next) == BARRIER)
2866 INSN_DELETED_P (next) = 1;
2867 next = NEXT_INSN (next);
2870 /* Patch out INSN (and the barrier if any) */
2872 if (! dont_really_delete)
2876 NEXT_INSN (prev) = next;
2877 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
2878 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
2879 XVECLEN (PATTERN (prev), 0) - 1)) = next;
2884 PREV_INSN (next) = prev;
2885 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
2886 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
2889 if (prev && NEXT_INSN (prev) == 0)
2890 set_last_insn (prev);
2893 /* If deleting a jump, decrement the count of the label,
2894 and delete the label if it is now unused. */
2896 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
2898 rtx lab = JUMP_LABEL (insn), lab_next;
2900 if (--LABEL_NUSES (lab) == 0)
2902 /* This can delete NEXT or PREV,
2903 either directly if NEXT is JUMP_LABEL (INSN),
2904 or indirectly through more levels of jumps. */
2907 /* I feel a little doubtful about this loop,
2908 but I see no clean and sure alternative way
2909 to find the first insn after INSN that is not now deleted.
2910 I hope this works. */
2911 while (next && INSN_DELETED_P (next))
2912 next = NEXT_INSN (next);
2915 else if ((lab_next = next_nonnote_insn (lab)) != NULL
2916 && GET_CODE (lab_next) == JUMP_INSN
2917 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
2918 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
2920 /* If we're deleting the tablejump, delete the dispatch table.
2921 We may not be able to kill the label immediately preceeding
2922 just yet, as it might be referenced in code leading up to
2924 delete_insn (lab_next);
2928 /* Likewise if we're deleting a dispatch table. */
2930 if (GET_CODE (insn) == JUMP_INSN
2931 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2932 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2934 rtx pat = PATTERN (insn);
2935 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2936 int len = XVECLEN (pat, diff_vec_p);
2938 for (i = 0; i < len; i++)
2939 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
2940 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
2941 while (next && INSN_DELETED_P (next))
2942 next = NEXT_INSN (next);
2946 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
2947 prev = PREV_INSN (prev);
2949 /* If INSN was a label and a dispatch table follows it,
2950 delete the dispatch table. The tablejump must have gone already.
2951 It isn't useful to fall through into a table. */
2954 && NEXT_INSN (insn) != 0
2955 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
2956 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
2957 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
2958 next = delete_insn (NEXT_INSN (insn));
2960 /* If INSN was a label, delete insns following it if now unreachable. */
2962 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
2964 register RTX_CODE code;
2966 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
2967 || code == NOTE || code == BARRIER
2968 || (code == CODE_LABEL && INSN_DELETED_P (next))))
2971 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
2972 next = NEXT_INSN (next);
2973 /* Keep going past other deleted labels to delete what follows. */
2974 else if (code == CODE_LABEL && INSN_DELETED_P (next))
2975 next = NEXT_INSN (next);
2977 /* Note: if this deletes a jump, it can cause more
2978 deletion of unreachable code, after a different label.
2979 As long as the value from this recursive call is correct,
2980 this invocation functions correctly. */
2981 next = delete_insn (next);
2988 /* Advance from INSN till reaching something not deleted
2989 then return that. May return INSN itself. */
2992 next_nondeleted_insn (insn)
2995 while (INSN_DELETED_P (insn))
2996 insn = NEXT_INSN (insn);
3000 /* Delete a range of insns from FROM to TO, inclusive.
3001 This is for the sake of peephole optimization, so assume
3002 that whatever these insns do will still be done by a new
3003 peephole insn that will replace them. */
3006 delete_for_peephole (from, to)
3007 register rtx from, to;
3009 register rtx insn = from;
3013 register rtx next = NEXT_INSN (insn);
3014 register rtx prev = PREV_INSN (insn);
3016 if (GET_CODE (insn) != NOTE)
3018 INSN_DELETED_P (insn) = 1;
3020 /* Patch this insn out of the chain. */
3021 /* We don't do this all at once, because we
3022 must preserve all NOTEs. */
3024 NEXT_INSN (prev) = next;
3027 PREV_INSN (next) = prev;
3035 /* Note that if TO is an unconditional jump
3036 we *do not* delete the BARRIER that follows,
3037 since the peephole that replaces this sequence
3038 is also an unconditional jump in that case. */
3041 /* We have determined that INSN is never reached, and are about to
3042 delete it. Print a warning if the user asked for one.
3044 To try to make this warning more useful, this should only be called
3045 once per basic block not reached, and it only warns when the basic
3046 block contains more than one line from the current function, and
3047 contains at least one operation. CSE and inlining can duplicate insns,
3048 so it's possible to get spurious warnings from this. */
3051 never_reached_warning (avoided_insn)
3055 rtx a_line_note = NULL;
3056 int two_avoided_lines = 0;
3057 int contains_insn = 0;
3059 if (! warn_notreached)
3062 /* Scan forwards, looking at LINE_NUMBER notes, until
3063 we hit a LABEL or we run out of insns. */
3065 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
3067 if (GET_CODE (insn) == CODE_LABEL)
3069 else if (GET_CODE (insn) == NOTE /* A line number note? */
3070 && NOTE_LINE_NUMBER (insn) >= 0)
3072 if (a_line_note == NULL)
3075 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
3076 != NOTE_LINE_NUMBER (insn));
3078 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
3081 if (two_avoided_lines && contains_insn)
3082 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
3083 NOTE_LINE_NUMBER (a_line_note),
3084 "will never be executed");
3087 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
3088 NLABEL as a return. Accrue modifications into the change group. */
3091 redirect_exp_1 (loc, olabel, nlabel, insn)
3096 register rtx x = *loc;
3097 register RTX_CODE code = GET_CODE (x);
3099 register const char *fmt;
3101 if (code == LABEL_REF)
3103 if (XEXP (x, 0) == olabel)
3107 n = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3109 n = gen_rtx_RETURN (VOIDmode);
3111 validate_change (insn, loc, n, 1);
3115 else if (code == RETURN && olabel == 0)
3117 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3118 if (loc == &PATTERN (insn))
3119 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
3120 validate_change (insn, loc, x, 1);
3124 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3125 && GET_CODE (SET_SRC (x)) == LABEL_REF
3126 && XEXP (SET_SRC (x), 0) == olabel)
3128 validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 1);
3132 fmt = GET_RTX_FORMAT (code);
3133 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3136 redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
3137 else if (fmt[i] == 'E')
3140 for (j = 0; j < XVECLEN (x, i); j++)
3141 redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
3146 /* Similar, but apply the change group and report success or failure. */
3149 redirect_exp (loc, olabel, nlabel, insn)
3154 redirect_exp_1 (loc, olabel, nlabel, insn);
3155 if (num_validated_changes () == 0)
3158 return apply_change_group ();
3161 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
3162 the modifications into the change group. Return false if we did
3163 not see how to do that. */
3166 redirect_jump_1 (jump, nlabel)
3169 int ochanges = num_validated_changes ();
3170 redirect_exp_1 (&PATTERN (jump), JUMP_LABEL (jump), nlabel, jump);
3171 return num_validated_changes () > ochanges;
3174 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
3175 jump target label is unused as a result, it and the code following
3178 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3181 The return value will be 1 if the change was made, 0 if it wasn't
3182 (this can only occur for NLABEL == 0). */
3185 redirect_jump (jump, nlabel, delete_unused)
3189 register rtx olabel = JUMP_LABEL (jump);
3191 if (nlabel == olabel)
3194 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3197 /* If this is an unconditional branch, delete it from the jump_chain of
3198 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3199 have UID's in range and JUMP_CHAIN is valid). */
3200 if (jump_chain && (simplejump_p (jump)
3201 || GET_CODE (PATTERN (jump)) == RETURN))
3203 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3205 delete_from_jump_chain (jump);
3206 if (label_index < max_jump_chain
3207 && INSN_UID (jump) < max_jump_chain)
3209 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3210 jump_chain[label_index] = jump;
3214 JUMP_LABEL (jump) = nlabel;
3216 ++LABEL_NUSES (nlabel);
3218 /* If we're eliding the jump over exception cleanups at the end of a
3219 function, move the function end note so that -Wreturn-type works. */
3220 if (olabel && NEXT_INSN (olabel)
3221 && GET_CODE (NEXT_INSN (olabel)) == NOTE
3222 && NOTE_LINE_NUMBER (NEXT_INSN (olabel)) == NOTE_INSN_FUNCTION_END)
3223 emit_note_after (NOTE_INSN_FUNCTION_END, nlabel);
3225 if (olabel && --LABEL_NUSES (olabel) == 0 && delete_unused)
3226 delete_insn (olabel);
3231 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3232 Accrue the modifications into the change group. */
3235 invert_exp_1 (x, insn)
3239 register RTX_CODE code;
3241 register const char *fmt;
3243 code = GET_CODE (x);
3245 if (code == IF_THEN_ELSE)
3247 register rtx comp = XEXP (x, 0);
3250 /* We can do this in two ways: The preferable way, which can only
3251 be done if this is not an integer comparison, is to reverse
3252 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3253 of the IF_THEN_ELSE. If we can't do either, fail. */
3255 if (can_reverse_comparison_p (comp, insn))
3257 validate_change (insn, &XEXP (x, 0),
3258 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
3259 GET_MODE (comp), XEXP (comp, 0),
3266 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3267 validate_change (insn, &XEXP (x, 2), tem, 1);
3271 fmt = GET_RTX_FORMAT (code);
3272 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3275 invert_exp_1 (XEXP (x, i), insn);
3276 else if (fmt[i] == 'E')
3279 for (j = 0; j < XVECLEN (x, i); j++)
3280 invert_exp_1 (XVECEXP (x, i, j), insn);
3285 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3287 Return 1 if we can do so, 0 if we cannot find a way to do so that
3288 matches a pattern. */
3291 invert_exp (x, insn)
3295 invert_exp_1 (x, insn);
3296 if (num_validated_changes () == 0)
3299 return apply_change_group ();
3302 /* Invert the condition of the jump JUMP, and make it jump to label
3303 NLABEL instead of where it jumps now. Accrue changes into the
3304 change group. Return false if we didn't see how to perform the
3305 inversion and redirection. */
3308 invert_jump_1 (jump, nlabel)
3313 ochanges = num_validated_changes ();
3314 invert_exp_1 (PATTERN (jump), jump);
3315 if (num_validated_changes () == ochanges)
3318 return redirect_jump_1 (jump, nlabel);
3321 /* Invert the condition of the jump JUMP, and make it jump to label
3322 NLABEL instead of where it jumps now. Return true if successful. */
3325 invert_jump (jump, nlabel, delete_unused)
3329 /* We have to either invert the condition and change the label or
3330 do neither. Either operation could fail. We first try to invert
3331 the jump. If that succeeds, we try changing the label. If that fails,
3332 we invert the jump back to what it was. */
3334 if (! invert_exp (PATTERN (jump), jump))
3337 if (redirect_jump (jump, nlabel, delete_unused))
3339 /* An inverted jump means that a probability taken becomes a
3340 probability not taken. Subtract the branch probability from the
3341 probability base to convert it back to a taken probability. */
3343 rtx note = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3345 XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
3350 if (! invert_exp (PATTERN (jump), jump))
3351 /* This should just be putting it back the way it was. */
3357 /* Delete the instruction JUMP from any jump chain it might be on. */
3360 delete_from_jump_chain (jump)
3364 rtx olabel = JUMP_LABEL (jump);
3366 /* Handle unconditional jumps. */
3367 if (jump_chain && olabel != 0
3368 && INSN_UID (olabel) < max_jump_chain
3369 && simplejump_p (jump))
3370 index = INSN_UID (olabel);
3371 /* Handle return insns. */
3372 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3376 if (jump_chain[index] == jump)
3377 jump_chain[index] = jump_chain[INSN_UID (jump)];
3382 for (insn = jump_chain[index];
3384 insn = jump_chain[INSN_UID (insn)])
3385 if (jump_chain[INSN_UID (insn)] == jump)
3387 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3393 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3395 If the old jump target label (before the dispatch table) becomes unused,
3396 it and the dispatch table may be deleted. In that case, find the insn
3397 before the jump references that label and delete it and logical successors
3401 redirect_tablejump (jump, nlabel)
3404 register rtx olabel = JUMP_LABEL (jump);
3406 /* Add this jump to the jump_chain of NLABEL. */
3407 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3408 && INSN_UID (jump) < max_jump_chain)
3410 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3411 jump_chain[INSN_UID (nlabel)] = jump;
3414 PATTERN (jump) = gen_jump (nlabel);
3415 JUMP_LABEL (jump) = nlabel;
3416 ++LABEL_NUSES (nlabel);
3417 INSN_CODE (jump) = -1;
3419 if (--LABEL_NUSES (olabel) == 0)
3421 delete_labelref_insn (jump, olabel, 0);
3422 delete_insn (olabel);
3426 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3427 If we found one, delete it and then delete this insn if DELETE_THIS is
3428 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3431 delete_labelref_insn (insn, label, delete_this)
3438 if (GET_CODE (insn) != NOTE
3439 && reg_mentioned_p (label, PATTERN (insn)))
3450 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3451 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3465 /* Like rtx_equal_p except that it considers two REGs as equal
3466 if they renumber to the same value and considers two commutative
3467 operations to be the same if the order of the operands has been
3470 ??? Addition is not commutative on the PA due to the weird implicit
3471 space register selection rules for memory addresses. Therefore, we
3472 don't consider a + b == b + a.
3474 We could/should make this test a little tighter. Possibly only
3475 disabling it on the PA via some backend macro or only disabling this
3476 case when the PLUS is inside a MEM. */
3479 rtx_renumbered_equal_p (x, y)
3483 register RTX_CODE code = GET_CODE (x);
3484 register const char *fmt;
3489 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3490 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3491 && GET_CODE (SUBREG_REG (y)) == REG)))
3493 int reg_x = -1, reg_y = -1;
3494 int word_x = 0, word_y = 0;
3496 if (GET_MODE (x) != GET_MODE (y))
3499 /* If we haven't done any renumbering, don't
3500 make any assumptions. */
3501 if (reg_renumber == 0)
3502 return rtx_equal_p (x, y);
3506 reg_x = REGNO (SUBREG_REG (x));
3507 word_x = SUBREG_WORD (x);
3509 if (reg_renumber[reg_x] >= 0)
3511 reg_x = reg_renumber[reg_x] + word_x;
3519 if (reg_renumber[reg_x] >= 0)
3520 reg_x = reg_renumber[reg_x];
3523 if (GET_CODE (y) == SUBREG)
3525 reg_y = REGNO (SUBREG_REG (y));
3526 word_y = SUBREG_WORD (y);
3528 if (reg_renumber[reg_y] >= 0)
3530 reg_y = reg_renumber[reg_y];
3538 if (reg_renumber[reg_y] >= 0)
3539 reg_y = reg_renumber[reg_y];
3542 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3545 /* Now we have disposed of all the cases
3546 in which different rtx codes can match. */
3547 if (code != GET_CODE (y))
3559 return INTVAL (x) == INTVAL (y);
3562 /* We can't assume nonlocal labels have their following insns yet. */
3563 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3564 return XEXP (x, 0) == XEXP (y, 0);
3566 /* Two label-refs are equivalent if they point at labels
3567 in the same position in the instruction stream. */
3568 return (next_real_insn (XEXP (x, 0))
3569 == next_real_insn (XEXP (y, 0)));
3572 return XSTR (x, 0) == XSTR (y, 0);
3575 /* If we didn't match EQ equality above, they aren't the same. */
3582 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3584 if (GET_MODE (x) != GET_MODE (y))
3587 /* For commutative operations, the RTX match if the operand match in any
3588 order. Also handle the simple binary and unary cases without a loop.
3590 ??? Don't consider PLUS a commutative operator; see comments above. */
3591 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3593 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3594 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
3595 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
3596 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
3597 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3598 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3599 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
3600 else if (GET_RTX_CLASS (code) == '1')
3601 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
3603 /* Compare the elements. If any pair of corresponding elements
3604 fail to match, return 0 for the whole things. */
3606 fmt = GET_RTX_FORMAT (code);
3607 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3613 if (XWINT (x, i) != XWINT (y, i))
3618 if (XINT (x, i) != XINT (y, i))
3623 if (strcmp (XSTR (x, i), XSTR (y, i)))
3628 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3633 if (XEXP (x, i) != XEXP (y, i))
3640 if (XVECLEN (x, i) != XVECLEN (y, i))
3642 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3643 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3654 /* If X is a hard register or equivalent to one or a subregister of one,
3655 return the hard register number. If X is a pseudo register that was not
3656 assigned a hard register, return the pseudo register number. Otherwise,
3657 return -1. Any rtx is valid for X. */
3663 if (GET_CODE (x) == REG)
3665 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3666 return reg_renumber[REGNO (x)];
3669 if (GET_CODE (x) == SUBREG)
3671 int base = true_regnum (SUBREG_REG (x));
3672 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3673 return SUBREG_WORD (x) + base;
3678 /* Optimize code of the form:
3680 for (x = a[i]; x; ...)
3682 for (x = a[i]; x; ...)
3686 Loop optimize will change the above code into
3690 { ...; if (! (x = ...)) break; }
3693 { ...; if (! (x = ...)) break; }
3696 In general, if the first test fails, the program can branch
3697 directly to `foo' and skip the second try which is doomed to fail.
3698 We run this after loop optimization and before flow analysis. */
3700 /* When comparing the insn patterns, we track the fact that different
3701 pseudo-register numbers may have been used in each computation.
3702 The following array stores an equivalence -- same_regs[I] == J means
3703 that pseudo register I was used in the first set of tests in a context
3704 where J was used in the second set. We also count the number of such
3705 pending equivalences. If nonzero, the expressions really aren't the
3708 static int *same_regs;
3710 static int num_same_regs;
3712 /* Track any registers modified between the target of the first jump and
3713 the second jump. They never compare equal. */
3715 static char *modified_regs;
3717 /* Record if memory was modified. */
3719 static int modified_mem;
3721 /* Called via note_stores on each insn between the target of the first
3722 branch and the second branch. It marks any changed registers. */
3725 mark_modified_reg (dest, x, data)
3727 rtx x ATTRIBUTE_UNUSED;
3728 void *data ATTRIBUTE_UNUSED;
3733 if (GET_CODE (dest) == SUBREG)
3734 dest = SUBREG_REG (dest);
3736 if (GET_CODE (dest) == MEM)
3739 if (GET_CODE (dest) != REG)
3742 regno = REGNO (dest);
3743 if (regno >= FIRST_PSEUDO_REGISTER)
3744 modified_regs[regno] = 1;
3746 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3747 modified_regs[regno + i] = 1;
3750 /* F is the first insn in the chain of insns. */
3753 thread_jumps (f, max_reg, flag_before_loop)
3756 int flag_before_loop;
3758 /* Basic algorithm is to find a conditional branch,
3759 the label it may branch to, and the branch after
3760 that label. If the two branches test the same condition,
3761 walk back from both branch paths until the insn patterns
3762 differ, or code labels are hit. If we make it back to
3763 the target of the first branch, then we know that the first branch
3764 will either always succeed or always fail depending on the relative
3765 senses of the two branches. So adjust the first branch accordingly
3768 rtx label, b1, b2, t1, t2;
3769 enum rtx_code code1, code2;
3770 rtx b1op0, b1op1, b2op0, b2op1;
3775 /* Allocate register tables and quick-reset table. */
3776 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
3777 same_regs = (int *) xmalloc (max_reg * sizeof (int));
3778 all_reset = (int *) xmalloc (max_reg * sizeof (int));
3779 for (i = 0; i < max_reg; i++)
3786 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3788 /* Get to a candidate branch insn. */
3789 if (GET_CODE (b1) != JUMP_INSN
3790 || ! condjump_p (b1) || simplejump_p (b1)
3791 || JUMP_LABEL (b1) == 0)
3794 bzero (modified_regs, max_reg * sizeof (char));
3797 bcopy ((char *) all_reset, (char *) same_regs,
3798 max_reg * sizeof (int));
3801 label = JUMP_LABEL (b1);
3803 /* Look for a branch after the target. Record any registers and
3804 memory modified between the target and the branch. Stop when we
3805 get to a label since we can't know what was changed there. */
3806 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
3808 if (GET_CODE (b2) == CODE_LABEL)
3811 else if (GET_CODE (b2) == JUMP_INSN)
3813 /* If this is an unconditional jump and is the only use of
3814 its target label, we can follow it. */
3815 if (simplejump_p (b2)
3816 && JUMP_LABEL (b2) != 0
3817 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
3819 b2 = JUMP_LABEL (b2);
3826 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
3829 if (GET_CODE (b2) == CALL_INSN)
3832 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3833 if (call_used_regs[i] && ! fixed_regs[i]
3834 && i != STACK_POINTER_REGNUM
3835 && i != FRAME_POINTER_REGNUM
3836 && i != HARD_FRAME_POINTER_REGNUM
3837 && i != ARG_POINTER_REGNUM)
3838 modified_regs[i] = 1;
3841 note_stores (PATTERN (b2), mark_modified_reg, NULL);
3844 /* Check the next candidate branch insn from the label
3847 || GET_CODE (b2) != JUMP_INSN
3849 || ! condjump_p (b2)
3850 || simplejump_p (b2))
3853 /* Get the comparison codes and operands, reversing the
3854 codes if appropriate. If we don't have comparison codes,
3855 we can't do anything. */
3856 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
3857 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
3858 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
3859 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
3860 code1 = reverse_condition (code1);
3862 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
3863 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
3864 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
3865 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
3866 code2 = reverse_condition (code2);
3868 /* If they test the same things and knowing that B1 branches
3869 tells us whether or not B2 branches, check if we
3870 can thread the branch. */
3871 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
3872 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
3873 && (comparison_dominates_p (code1, code2)
3874 || (can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
3877 && comparison_dominates_p (code1, reverse_condition (code2)))))
3880 t1 = prev_nonnote_insn (b1);
3881 t2 = prev_nonnote_insn (b2);
3883 while (t1 != 0 && t2 != 0)
3887 /* We have reached the target of the first branch.
3888 If there are no pending register equivalents,
3889 we know that this branch will either always
3890 succeed (if the senses of the two branches are
3891 the same) or always fail (if not). */
3894 if (num_same_regs != 0)
3897 if (comparison_dominates_p (code1, code2))
3898 new_label = JUMP_LABEL (b2);
3900 new_label = get_label_after (b2);
3902 if (JUMP_LABEL (b1) != new_label)
3904 rtx prev = PREV_INSN (new_label);
3906 if (flag_before_loop
3907 && GET_CODE (prev) == NOTE
3908 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
3910 /* Don't thread to the loop label. If a loop
3911 label is reused, loop optimization will
3912 be disabled for that loop. */
3913 new_label = gen_label_rtx ();
3914 emit_label_after (new_label, PREV_INSN (prev));
3916 changed |= redirect_jump (b1, new_label, 1);
3921 /* If either of these is not a normal insn (it might be
3922 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3923 have already been skipped above.) Similarly, fail
3924 if the insns are different. */
3925 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
3926 || recog_memoized (t1) != recog_memoized (t2)
3927 || ! rtx_equal_for_thread_p (PATTERN (t1),
3931 t1 = prev_nonnote_insn (t1);
3932 t2 = prev_nonnote_insn (t2);
3939 free (modified_regs);
3944 /* This is like RTX_EQUAL_P except that it knows about our handling of
3945 possibly equivalent registers and knows to consider volatile and
3946 modified objects as not equal.
3948 YINSN is the insn containing Y. */
3951 rtx_equal_for_thread_p (x, y, yinsn)
3957 register enum rtx_code code;
3958 register const char *fmt;
3960 code = GET_CODE (x);
3961 /* Rtx's of different codes cannot be equal. */
3962 if (code != GET_CODE (y))
3965 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
3966 (REG:SI x) and (REG:HI x) are NOT equivalent. */
3968 if (GET_MODE (x) != GET_MODE (y))
3971 /* For floating-point, consider everything unequal. This is a bit
3972 pessimistic, but this pass would only rarely do anything for FP
3974 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3975 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
3978 /* For commutative operations, the RTX match if the operand match in any
3979 order. Also handle the simple binary and unary cases without a loop. */
3980 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3981 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
3982 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
3983 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
3984 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
3985 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3986 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
3987 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
3988 else if (GET_RTX_CLASS (code) == '1')
3989 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
3991 /* Handle special-cases first. */
3995 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
3998 /* If neither is user variable or hard register, check for possible
4000 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4001 || REGNO (x) < FIRST_PSEUDO_REGISTER
4002 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4005 if (same_regs[REGNO (x)] == -1)
4007 same_regs[REGNO (x)] = REGNO (y);
4010 /* If this is the first time we are seeing a register on the `Y'
4011 side, see if it is the last use. If not, we can't thread the
4012 jump, so mark it as not equivalent. */
4013 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4019 return (same_regs[REGNO (x)] == (int) REGNO (y));
4024 /* If memory modified or either volatile, not equivalent.
4025 Else, check address. */
4026 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4029 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4032 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4038 /* Cancel a pending `same_regs' if setting equivalenced registers.
4039 Then process source. */
4040 if (GET_CODE (SET_DEST (x)) == REG
4041 && GET_CODE (SET_DEST (y)) == REG)
4043 if (same_regs[REGNO (SET_DEST (x))] == (int) REGNO (SET_DEST (y)))
4045 same_regs[REGNO (SET_DEST (x))] = -1;
4048 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4052 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4055 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4058 return XEXP (x, 0) == XEXP (y, 0);
4061 return XSTR (x, 0) == XSTR (y, 0);
4070 fmt = GET_RTX_FORMAT (code);
4071 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4076 if (XWINT (x, i) != XWINT (y, i))
4082 if (XINT (x, i) != XINT (y, i))
4088 /* Two vectors must have the same length. */
4089 if (XVECLEN (x, i) != XVECLEN (y, i))
4092 /* And the corresponding elements must match. */
4093 for (j = 0; j < XVECLEN (x, i); j++)
4094 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4095 XVECEXP (y, i, j), yinsn) == 0)
4100 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4106 if (strcmp (XSTR (x, i), XSTR (y, i)))
4111 /* These are just backpointers, so they don't matter. */
4118 /* It is believed that rtx's at this level will never
4119 contain anything but integers and other rtx's,
4120 except for within LABEL_REFs and SYMBOL_REFs. */