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 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
249 LABEL_NUSES (XEXP (insn, 0))++;
251 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
252 notes and recompute LABEL_NUSES. */
253 if (mark_labels_only)
257 exception_optimize ();
259 last_insn = delete_unreferenced_labels (f);
262 delete_noop_moves (f);
264 /* If we haven't yet gotten to reload and we have just run regscan,
265 delete any insn that sets a register that isn't used elsewhere.
266 This helps some of the optimizations below by having less insns
267 being jumped around. */
269 if (optimize && ! reload_completed && after_regscan)
270 for (insn = f; insn; insn = next)
272 rtx set = single_set (insn);
274 next = NEXT_INSN (insn);
276 if (set && GET_CODE (SET_DEST (set)) == REG
277 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
278 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
279 /* We use regno_last_note_uid so as not to delete the setting
280 of a reg that's used in notes. A subsequent optimization
281 might arrange to use that reg for real. */
282 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
283 && ! side_effects_p (SET_SRC (set))
284 && ! find_reg_note (insn, REG_RETVAL, 0)
285 /* An ADDRESSOF expression can turn into a use of the internal arg
286 pointer, so do not delete the initialization of the internal
287 arg pointer yet. If it is truly dead, flow will delete the
288 initializing insn. */
289 && SET_DEST (set) != current_function_internal_arg_pointer)
293 /* Now iterate optimizing jumps until nothing changes over one pass. */
295 old_max_reg = max_reg_num ();
300 for (insn = f; insn; insn = next)
303 rtx temp, temp1, temp2 = NULL_RTX;
304 rtx temp4 ATTRIBUTE_UNUSED;
306 int this_is_simplejump, this_is_condjump;
307 int this_is_condjump_in_parallel;
309 next = NEXT_INSN (insn);
311 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
312 jump. Try to optimize by duplicating the loop exit test if so.
313 This is only safe immediately after regscan, because it uses
314 the values of regno_first_uid and regno_last_uid. */
315 if (after_regscan && GET_CODE (insn) == NOTE
316 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
317 && (temp1 = next_nonnote_insn (insn)) != 0
318 && simplejump_p (temp1))
320 temp = PREV_INSN (insn);
321 if (duplicate_loop_exit_test (insn))
324 next = NEXT_INSN (temp);
329 if (GET_CODE (insn) != JUMP_INSN)
332 this_is_simplejump = simplejump_p (insn);
333 this_is_condjump = condjump_p (insn);
334 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
336 /* Tension the labels in dispatch tables. */
338 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
339 changed |= tension_vector_labels (PATTERN (insn), 0);
340 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
341 changed |= tension_vector_labels (PATTERN (insn), 1);
343 /* See if this jump goes to another jump and redirect if so. */
344 nlabel = follow_jumps (JUMP_LABEL (insn));
345 if (nlabel != JUMP_LABEL (insn))
346 changed |= redirect_jump (insn, nlabel, 1);
348 if (! optimize || minimal)
351 /* If a dispatch table always goes to the same place,
352 get rid of it and replace the insn that uses it. */
354 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
355 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
358 rtx pat = PATTERN (insn);
359 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
360 int len = XVECLEN (pat, diff_vec_p);
361 rtx dispatch = prev_real_insn (insn);
364 for (i = 0; i < len; i++)
365 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
366 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
371 && GET_CODE (dispatch) == JUMP_INSN
372 && JUMP_LABEL (dispatch) != 0
373 /* Don't mess with a casesi insn.
374 XXX according to the comment before computed_jump_p(),
375 all casesi insns should be a parallel of the jump
376 and a USE of a LABEL_REF. */
377 && ! ((set = single_set (dispatch)) != NULL
378 && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE))
379 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
381 redirect_tablejump (dispatch,
382 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
387 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
389 /* Detect jump to following insn. */
390 if (reallabelprev == insn && this_is_condjump)
392 next = next_real_insn (JUMP_LABEL (insn));
395 /* Remove the "inactive" but "real" insns (i.e. uses and
396 clobbers) in between here and there. */
398 while ((temp = next_real_insn (temp)) != next)
405 /* Detect a conditional jump going to the same place
406 as an immediately following unconditional jump. */
407 else if (this_is_condjump
408 && (temp = next_active_insn (insn)) != 0
409 && simplejump_p (temp)
410 && (next_active_insn (JUMP_LABEL (insn))
411 == next_active_insn (JUMP_LABEL (temp))))
413 /* Don't mess up test coverage analysis. */
415 if (flag_test_coverage && !reload_completed)
416 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
417 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
428 /* Detect a conditional jump jumping over an unconditional jump. */
430 else if ((this_is_condjump || this_is_condjump_in_parallel)
431 && ! this_is_simplejump
432 && reallabelprev != 0
433 && GET_CODE (reallabelprev) == JUMP_INSN
434 && prev_active_insn (reallabelprev) == insn
435 && no_labels_between_p (insn, reallabelprev)
436 && simplejump_p (reallabelprev))
438 /* When we invert the unconditional jump, we will be
439 decrementing the usage count of its old label.
440 Make sure that we don't delete it now because that
441 might cause the following code to be deleted. */
442 rtx prev_uses = prev_nonnote_insn (reallabelprev);
443 rtx prev_label = JUMP_LABEL (insn);
446 ++LABEL_NUSES (prev_label);
448 if (invert_jump (insn, JUMP_LABEL (reallabelprev), 1))
450 /* It is very likely that if there are USE insns before
451 this jump, they hold REG_DEAD notes. These REG_DEAD
452 notes are no longer valid due to this optimization,
453 and will cause the life-analysis that following passes
454 (notably delayed-branch scheduling) to think that
455 these registers are dead when they are not.
457 To prevent this trouble, we just remove the USE insns
458 from the insn chain. */
460 while (prev_uses && GET_CODE (prev_uses) == INSN
461 && GET_CODE (PATTERN (prev_uses)) == USE)
463 rtx useless = prev_uses;
464 prev_uses = prev_nonnote_insn (prev_uses);
465 delete_insn (useless);
468 delete_insn (reallabelprev);
472 /* We can now safely delete the label if it is unreferenced
473 since the delete_insn above has deleted the BARRIER. */
474 if (prev_label && --LABEL_NUSES (prev_label) == 0)
475 delete_insn (prev_label);
477 next = NEXT_INSN (insn);
480 /* If we have an unconditional jump preceded by a USE, try to put
481 the USE before the target and jump there. This simplifies many
482 of the optimizations below since we don't have to worry about
483 dealing with these USE insns. We only do this if the label
484 being branch to already has the identical USE or if code
485 never falls through to that label. */
487 else if (this_is_simplejump
488 && (temp = prev_nonnote_insn (insn)) != 0
489 && GET_CODE (temp) == INSN
490 && GET_CODE (PATTERN (temp)) == USE
491 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
492 && (GET_CODE (temp1) == BARRIER
493 || (GET_CODE (temp1) == INSN
494 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
495 /* Don't do this optimization if we have a loop containing
496 only the USE instruction, and the loop start label has
497 a usage count of 1. This is because we will redo this
498 optimization everytime through the outer loop, and jump
499 opt will never exit. */
500 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
501 && temp2 == JUMP_LABEL (insn)
502 && LABEL_NUSES (temp2) == 1))
504 if (GET_CODE (temp1) == BARRIER)
506 emit_insn_after (PATTERN (temp), temp1);
507 temp1 = NEXT_INSN (temp1);
511 redirect_jump (insn, get_label_before (temp1), 1);
512 reallabelprev = prev_real_insn (temp1);
514 next = NEXT_INSN (insn);
518 /* Detect a conditional jump jumping over an unconditional trap. */
520 && this_is_condjump && ! this_is_simplejump
521 && reallabelprev != 0
522 && GET_CODE (reallabelprev) == INSN
523 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
524 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
525 && prev_active_insn (reallabelprev) == insn
526 && no_labels_between_p (insn, reallabelprev)
527 && (temp2 = get_condition (insn, &temp4))
528 && can_reverse_comparison_p (temp2, insn))
530 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
531 XEXP (temp2, 0), XEXP (temp2, 1),
532 TRAP_CODE (PATTERN (reallabelprev)));
536 emit_insn_before (new, temp4);
537 delete_insn (reallabelprev);
543 /* Detect a jump jumping to an unconditional trap. */
544 else if (HAVE_trap && this_is_condjump
545 && (temp = next_active_insn (JUMP_LABEL (insn)))
546 && GET_CODE (temp) == INSN
547 && GET_CODE (PATTERN (temp)) == TRAP_IF
548 && (this_is_simplejump
549 || (temp2 = get_condition (insn, &temp4))))
551 rtx tc = TRAP_CONDITION (PATTERN (temp));
553 if (tc == const_true_rtx
554 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
557 /* Replace an unconditional jump to a trap with a trap. */
558 if (this_is_simplejump)
560 emit_barrier_after (emit_insn_before (gen_trap (), insn));
565 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
567 TRAP_CODE (PATTERN (temp)));
570 emit_insn_before (new, temp4);
576 /* If the trap condition and jump condition are mutually
577 exclusive, redirect the jump to the following insn. */
578 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
579 && ! this_is_simplejump
580 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
581 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
582 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
583 && redirect_jump (insn, get_label_after (temp), 1))
592 /* Now that the jump has been tensioned,
593 try cross jumping: check for identical code
594 before the jump and before its target label. */
596 /* First, cross jumping of conditional jumps: */
598 if (cross_jump && condjump_p (insn))
600 rtx newjpos, newlpos;
601 rtx x = prev_real_insn (JUMP_LABEL (insn));
603 /* A conditional jump may be crossjumped
604 only if the place it jumps to follows
605 an opposing jump that comes back here. */
607 if (x != 0 && ! jump_back_p (x, insn))
608 /* We have no opposing jump;
609 cannot cross jump this insn. */
613 /* TARGET is nonzero if it is ok to cross jump
614 to code before TARGET. If so, see if matches. */
616 find_cross_jump (insn, x,
617 (optimize_size ? 1 : BRANCH_COST) + 1,
622 do_cross_jump (insn, newjpos, newlpos);
623 /* Make the old conditional jump
624 into an unconditional one. */
625 SET_SRC (PATTERN (insn))
626 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
627 INSN_CODE (insn) = -1;
628 emit_barrier_after (insn);
629 /* Add to jump_chain unless this is a new label
630 whose UID is too large. */
631 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
633 jump_chain[INSN_UID (insn)]
634 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
635 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
642 /* Cross jumping of unconditional jumps:
643 a few differences. */
645 if (cross_jump && simplejump_p (insn))
647 rtx newjpos, newlpos;
652 /* TARGET is nonzero if it is ok to cross jump
653 to code before TARGET. If so, see if matches. */
654 find_cross_jump (insn, JUMP_LABEL (insn),
655 optimize_size ? 1 : BRANCH_COST,
658 /* If cannot cross jump to code before the label,
659 see if we can cross jump to another jump to
661 /* Try each other jump to this label. */
662 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
663 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
664 target != 0 && newjpos == 0;
665 target = jump_chain[INSN_UID (target)])
667 && JUMP_LABEL (target) == JUMP_LABEL (insn)
668 /* Ignore TARGET if it's deleted. */
669 && ! INSN_DELETED_P (target))
670 find_cross_jump (insn, target,
671 (optimize_size ? 1 : BRANCH_COST) + 1,
676 do_cross_jump (insn, newjpos, newlpos);
682 /* This code was dead in the previous jump.c! */
683 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
685 /* Return insns all "jump to the same place"
686 so we can cross-jump between any two of them. */
688 rtx newjpos, newlpos, target;
692 /* If cannot cross jump to code before the label,
693 see if we can cross jump to another jump to
695 /* Try each other jump to this label. */
696 for (target = jump_chain[0];
697 target != 0 && newjpos == 0;
698 target = jump_chain[INSN_UID (target)])
700 && ! INSN_DELETED_P (target)
701 && GET_CODE (PATTERN (target)) == RETURN)
702 find_cross_jump (insn, target,
703 (optimize_size ? 1 : BRANCH_COST) + 1,
708 do_cross_jump (insn, newjpos, newlpos);
719 /* Delete extraneous line number notes.
720 Note that two consecutive notes for different lines are not really
721 extraneous. There should be some indication where that line belonged,
722 even if it became empty. */
727 for (insn = f; insn; insn = NEXT_INSN (insn))
728 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
730 /* Delete this note if it is identical to previous note. */
732 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
733 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
743 /* CAN_REACH_END is persistent for each function. Once set it should
744 not be cleared. This is especially true for the case where we
745 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
746 the front-end before compiling each function. */
747 if (! minimal && calculate_can_reach_end (last_insn, optimize != 0))
756 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
757 notes whose labels don't occur in the insn any more. Returns the
758 largest INSN_UID found. */
766 for (insn = f; insn; insn = NEXT_INSN (insn))
768 if (GET_CODE (insn) == CODE_LABEL)
769 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
770 else if (GET_CODE (insn) == JUMP_INSN)
771 JUMP_LABEL (insn) = 0;
772 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
776 for (note = REG_NOTES (insn); note; note = next)
778 next = XEXP (note, 1);
779 if (REG_NOTE_KIND (note) == REG_LABEL
780 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
781 remove_note (insn, note);
784 if (INSN_UID (insn) > largest_uid)
785 largest_uid = INSN_UID (insn);
791 /* Delete insns following barriers, up to next label.
793 Also delete no-op jumps created by gcse. */
796 delete_barrier_successors (f)
801 for (insn = f; insn;)
803 if (GET_CODE (insn) == BARRIER)
805 insn = NEXT_INSN (insn);
807 never_reached_warning (insn);
809 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
811 if (GET_CODE (insn) == NOTE
812 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
813 insn = NEXT_INSN (insn);
815 insn = delete_insn (insn);
817 /* INSN is now the code_label. */
820 /* Also remove (set (pc) (pc)) insns which can be created by
821 gcse. We eliminate such insns now to avoid having them
822 cause problems later. */
823 else if (GET_CODE (insn) == JUMP_INSN
824 && GET_CODE (PATTERN (insn)) == SET
825 && SET_SRC (PATTERN (insn)) == pc_rtx
826 && SET_DEST (PATTERN (insn)) == pc_rtx)
827 insn = delete_insn (insn);
830 insn = NEXT_INSN (insn);
834 /* Mark the label each jump jumps to.
835 Combine consecutive labels, and count uses of labels.
837 For each label, make a chain (using `jump_chain')
838 of all the *unconditional* jumps that jump to it;
839 also make a chain of all returns.
841 CROSS_JUMP indicates whether we are doing cross jumping
842 and if we are whether we will be paying attention to
843 death notes or not. */
846 mark_all_labels (f, cross_jump)
852 for (insn = f; insn; insn = NEXT_INSN (insn))
853 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
855 if (GET_CODE (insn) == CALL_INSN
856 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
858 mark_all_labels (XEXP (PATTERN (insn), 0), cross_jump);
859 mark_all_labels (XEXP (PATTERN (insn), 1), cross_jump);
860 mark_all_labels (XEXP (PATTERN (insn), 2), cross_jump);
864 mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
865 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
867 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
869 jump_chain[INSN_UID (insn)]
870 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
871 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
873 if (GET_CODE (PATTERN (insn)) == RETURN)
875 jump_chain[INSN_UID (insn)] = jump_chain[0];
876 jump_chain[0] = insn;
882 /* Delete all labels already not referenced.
883 Also find and return the last insn. */
886 delete_unreferenced_labels (f)
889 rtx final = NULL_RTX;
892 for (insn = f; insn; )
894 if (GET_CODE (insn) == CODE_LABEL
895 && LABEL_NUSES (insn) == 0
896 && LABEL_ALTERNATE_NAME (insn) == NULL)
897 insn = delete_insn (insn);
901 insn = NEXT_INSN (insn);
908 /* Delete various simple forms of moves which have no necessary
912 delete_noop_moves (f)
917 for (insn = f; insn; )
919 next = NEXT_INSN (insn);
921 if (GET_CODE (insn) == INSN)
923 register rtx body = PATTERN (insn);
925 /* Detect and delete no-op move instructions
926 resulting from not allocating a parameter in a register. */
928 if (GET_CODE (body) == SET
929 && (SET_DEST (body) == SET_SRC (body)
930 || (GET_CODE (SET_DEST (body)) == MEM
931 && GET_CODE (SET_SRC (body)) == MEM
932 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
933 && ! (GET_CODE (SET_DEST (body)) == MEM
934 && MEM_VOLATILE_P (SET_DEST (body)))
935 && ! (GET_CODE (SET_SRC (body)) == MEM
936 && MEM_VOLATILE_P (SET_SRC (body))))
937 delete_computation (insn);
939 /* Detect and ignore no-op move instructions
940 resulting from smart or fortuitous register allocation. */
942 else if (GET_CODE (body) == SET)
944 int sreg = true_regnum (SET_SRC (body));
945 int dreg = true_regnum (SET_DEST (body));
947 if (sreg == dreg && sreg >= 0)
949 else if (sreg >= 0 && dreg >= 0)
952 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
953 sreg, NULL_PTR, dreg,
954 GET_MODE (SET_SRC (body)));
957 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
959 /* DREG may have been the target of a REG_DEAD note in
960 the insn which makes INSN redundant. If so, reorg
961 would still think it is dead. So search for such a
962 note and delete it if we find it. */
963 if (! find_regno_note (insn, REG_UNUSED, dreg))
964 for (trial = prev_nonnote_insn (insn);
965 trial && GET_CODE (trial) != CODE_LABEL;
966 trial = prev_nonnote_insn (trial))
967 if (find_regno_note (trial, REG_DEAD, dreg))
969 remove_death (dreg, trial);
973 /* Deleting insn could lose a death-note for SREG. */
974 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
976 /* Change this into a USE so that we won't emit
977 code for it, but still can keep the note. */
979 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
980 INSN_CODE (insn) = -1;
981 /* Remove all reg notes but the REG_DEAD one. */
982 REG_NOTES (insn) = trial;
983 XEXP (trial, 1) = NULL_RTX;
989 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
990 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
992 GET_MODE (SET_DEST (body))))
994 /* This handles the case where we have two consecutive
995 assignments of the same constant to pseudos that didn't
996 get a hard reg. Each SET from the constant will be
997 converted into a SET of the spill register and an
998 output reload will be made following it. This produces
999 two loads of the same constant into the same spill
1004 /* Look back for a death note for the first reg.
1005 If there is one, it is no longer accurate. */
1006 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
1008 if ((GET_CODE (in_insn) == INSN
1009 || GET_CODE (in_insn) == JUMP_INSN)
1010 && find_regno_note (in_insn, REG_DEAD, dreg))
1012 remove_death (dreg, in_insn);
1015 in_insn = PREV_INSN (in_insn);
1018 /* Delete the second load of the value. */
1022 else if (GET_CODE (body) == PARALLEL)
1024 /* If each part is a set between two identical registers or
1025 a USE or CLOBBER, delete the insn. */
1029 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
1031 tem = XVECEXP (body, 0, i);
1032 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
1035 if (GET_CODE (tem) != SET
1036 || (sreg = true_regnum (SET_SRC (tem))) < 0
1037 || (dreg = true_regnum (SET_DEST (tem))) < 0
1045 /* Also delete insns to store bit fields if they are no-ops. */
1046 /* Not worth the hair to detect this in the big-endian case. */
1047 else if (! BYTES_BIG_ENDIAN
1048 && GET_CODE (body) == SET
1049 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
1050 && XEXP (SET_DEST (body), 2) == const0_rtx
1051 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
1052 && ! (GET_CODE (SET_SRC (body)) == MEM
1053 && MEM_VOLATILE_P (SET_SRC (body))))
1060 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1061 If so indicate that this function can drop off the end by returning
1064 CHECK_DELETED indicates whether we must check if the note being
1065 searched for has the deleted flag set.
1067 DELETE_FINAL_NOTE indicates whether we should delete the note
1071 calculate_can_reach_end (last, delete_final_note)
1073 int delete_final_note;
1078 while (insn != NULL_RTX)
1082 /* One label can follow the end-note: the return label. */
1083 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
1085 /* Ordinary insns can follow it if returning a structure. */
1086 else if (GET_CODE (insn) == INSN)
1088 /* If machine uses explicit RETURN insns, no epilogue,
1089 then one of them follows the note. */
1090 else if (GET_CODE (insn) == JUMP_INSN
1091 && GET_CODE (PATTERN (insn)) == RETURN)
1093 /* A barrier can follow the return insn. */
1094 else if (GET_CODE (insn) == BARRIER)
1096 /* Other kinds of notes can follow also. */
1097 else if (GET_CODE (insn) == NOTE
1098 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
1104 insn = PREV_INSN (insn);
1107 /* See if we backed up to the appropriate type of note. */
1108 if (insn != NULL_RTX
1109 && GET_CODE (insn) == NOTE
1110 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
1112 if (delete_final_note)
1120 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1121 jump. Assume that this unconditional jump is to the exit test code. If
1122 the code is sufficiently simple, make a copy of it before INSN,
1123 followed by a jump to the exit of the loop. Then delete the unconditional
1126 Return 1 if we made the change, else 0.
1128 This is only safe immediately after a regscan pass because it uses the
1129 values of regno_first_uid and regno_last_uid. */
1132 duplicate_loop_exit_test (loop_start)
1135 rtx insn, set, reg, p, link;
1136 rtx copy = 0, first_copy = 0;
1138 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
1140 int max_reg = max_reg_num ();
1143 /* Scan the exit code. We do not perform this optimization if any insn:
1147 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1148 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1149 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1152 We also do not do this if we find an insn with ASM_OPERANDS. While
1153 this restriction should not be necessary, copying an insn with
1154 ASM_OPERANDS can confuse asm_noperands in some cases.
1156 Also, don't do this if the exit code is more than 20 insns. */
1158 for (insn = exitcode;
1160 && ! (GET_CODE (insn) == NOTE
1161 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
1162 insn = NEXT_INSN (insn))
1164 switch (GET_CODE (insn))
1170 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
1171 a jump immediately after the loop start that branches outside
1172 the loop but within an outer loop, near the exit test.
1173 If we copied this exit test and created a phony
1174 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
1175 before the exit test look like these could be safely moved
1176 out of the loop even if they actually may be never executed.
1177 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
1179 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1180 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
1184 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1185 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
1186 /* If we were to duplicate this code, we would not move
1187 the BLOCK notes, and so debugging the moved code would
1188 be difficult. Thus, we only move the code with -O2 or
1195 /* The code below would grossly mishandle REG_WAS_0 notes,
1196 so get rid of them here. */
1197 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
1198 remove_note (insn, p);
1199 if (++num_insns > 20
1200 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1201 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
1209 /* Unless INSN is zero, we can do the optimization. */
1215 /* See if any insn sets a register only used in the loop exit code and
1216 not a user variable. If so, replace it with a new register. */
1217 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1218 if (GET_CODE (insn) == INSN
1219 && (set = single_set (insn)) != 0
1220 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
1221 || (GET_CODE (reg) == SUBREG
1222 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
1223 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
1224 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
1226 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
1227 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
1232 /* We can do the replacement. Allocate reg_map if this is the
1233 first replacement we found. */
1235 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
1237 REG_LOOP_TEST_P (reg) = 1;
1239 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
1243 /* Now copy each insn. */
1244 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1246 switch (GET_CODE (insn))
1249 copy = emit_barrier_before (loop_start);
1252 /* Only copy line-number notes. */
1253 if (NOTE_LINE_NUMBER (insn) >= 0)
1255 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
1256 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
1261 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
1263 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1265 mark_jump_label (PATTERN (copy), copy, 0, 0);
1267 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1269 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1270 if (REG_NOTE_KIND (link) != REG_LABEL)
1272 if (GET_CODE (link) == EXPR_LIST)
1274 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
1279 = copy_insn_1 (gen_rtx_INSN_LIST (REG_NOTE_KIND (link),
1284 if (reg_map && REG_NOTES (copy))
1285 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1289 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)), loop_start);
1291 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1292 mark_jump_label (PATTERN (copy), copy, 0, 0);
1293 if (REG_NOTES (insn))
1295 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
1297 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1300 /* If this is a simple jump, add it to the jump chain. */
1302 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
1303 && simplejump_p (copy))
1305 jump_chain[INSN_UID (copy)]
1306 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1307 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1315 /* Record the first insn we copied. We need it so that we can
1316 scan the copied insns for new pseudo registers. */
1321 /* Now clean up by emitting a jump to the end label and deleting the jump
1322 at the start of the loop. */
1323 if (! copy || GET_CODE (copy) != BARRIER)
1325 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
1328 /* Record the first insn we copied. We need it so that we can
1329 scan the copied insns for new pseudo registers. This may not
1330 be strictly necessary since we should have copied at least one
1331 insn above. But I am going to be safe. */
1335 mark_jump_label (PATTERN (copy), copy, 0, 0);
1336 if (INSN_UID (copy) < max_jump_chain
1337 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
1339 jump_chain[INSN_UID (copy)]
1340 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1341 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1343 emit_barrier_before (loop_start);
1346 /* Now scan from the first insn we copied to the last insn we copied
1347 (copy) for new pseudo registers. Do this after the code to jump to
1348 the end label since that might create a new pseudo too. */
1349 reg_scan_update (first_copy, copy, max_reg);
1351 /* Mark the exit code as the virtual top of the converted loop. */
1352 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
1354 delete_insn (next_nonnote_insn (loop_start));
1363 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
1364 eh-beg, eh-end notes between START and END out before START. Assume that
1365 END is not such a note. START may be such a note. Returns the value
1366 of the new starting insn, which may be different if the original start
1370 squeeze_notes (start, end)
1376 for (insn = start; insn != end; insn = next)
1378 next = NEXT_INSN (insn);
1379 if (GET_CODE (insn) == NOTE
1380 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
1381 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1382 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1383 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
1384 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
1385 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP
1386 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1387 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1393 rtx prev = PREV_INSN (insn);
1394 PREV_INSN (insn) = PREV_INSN (start);
1395 NEXT_INSN (insn) = start;
1396 NEXT_INSN (PREV_INSN (insn)) = insn;
1397 PREV_INSN (NEXT_INSN (insn)) = insn;
1398 NEXT_INSN (prev) = next;
1399 PREV_INSN (next) = prev;
1407 /* Compare the instructions before insn E1 with those before E2
1408 to find an opportunity for cross jumping.
1409 (This means detecting identical sequences of insns followed by
1410 jumps to the same place, or followed by a label and a jump
1411 to that label, and replacing one with a jump to the other.)
1413 Assume E1 is a jump that jumps to label E2
1414 (that is not always true but it might as well be).
1415 Find the longest possible equivalent sequences
1416 and store the first insns of those sequences into *F1 and *F2.
1417 Store zero there if no equivalent preceding instructions are found.
1419 We give up if we find a label in stream 1.
1420 Actually we could transfer that label into stream 2. */
1423 find_cross_jump (e1, e2, minimum, f1, f2)
1428 register rtx i1 = e1, i2 = e2;
1429 register rtx p1, p2;
1432 rtx last1 = 0, last2 = 0;
1433 rtx afterlast1 = 0, afterlast2 = 0;
1440 i1 = prev_nonnote_insn (i1);
1442 i2 = PREV_INSN (i2);
1443 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
1444 i2 = PREV_INSN (i2);
1449 /* Don't allow the range of insns preceding E1 or E2
1450 to include the other (E2 or E1). */
1451 if (i2 == e1 || i1 == e2)
1454 /* If we will get to this code by jumping, those jumps will be
1455 tensioned to go directly to the new label (before I2),
1456 so this cross-jumping won't cost extra. So reduce the minimum. */
1457 if (GET_CODE (i1) == CODE_LABEL)
1463 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
1466 /* Avoid moving insns across EH regions if either of the insns
1469 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
1470 && !in_same_eh_region (i1, i2))
1476 /* If this is a CALL_INSN, compare register usage information.
1477 If we don't check this on stack register machines, the two
1478 CALL_INSNs might be merged leaving reg-stack.c with mismatching
1479 numbers of stack registers in the same basic block.
1480 If we don't check this on machines with delay slots, a delay slot may
1481 be filled that clobbers a parameter expected by the subroutine.
1483 ??? We take the simple route for now and assume that if they're
1484 equal, they were constructed identically. */
1486 if (GET_CODE (i1) == CALL_INSN
1487 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1488 CALL_INSN_FUNCTION_USAGE (i2)))
1492 /* If cross_jump_death_matters is not 0, the insn's mode
1493 indicates whether or not the insn contains any stack-like
1496 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
1498 /* If register stack conversion has already been done, then
1499 death notes must also be compared before it is certain that
1500 the two instruction streams match. */
1503 HARD_REG_SET i1_regset, i2_regset;
1505 CLEAR_HARD_REG_SET (i1_regset);
1506 CLEAR_HARD_REG_SET (i2_regset);
1508 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
1509 if (REG_NOTE_KIND (note) == REG_DEAD
1510 && STACK_REG_P (XEXP (note, 0)))
1511 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
1513 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1514 if (REG_NOTE_KIND (note) == REG_DEAD
1515 && STACK_REG_P (XEXP (note, 0)))
1516 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1518 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
1527 /* Don't allow old-style asm or volatile extended asms to be accepted
1528 for cross jumping purposes. It is conceptually correct to allow
1529 them, since cross-jumping preserves the dynamic instruction order
1530 even though it is changing the static instruction order. However,
1531 if an asm is being used to emit an assembler pseudo-op, such as
1532 the MIPS `.set reorder' pseudo-op, then the static instruction order
1533 matters and it must be preserved. */
1534 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
1535 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
1536 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
1539 if (lose || GET_CODE (p1) != GET_CODE (p2)
1540 || ! rtx_renumbered_equal_p (p1, p2))
1542 /* The following code helps take care of G++ cleanups. */
1546 if (!lose && GET_CODE (p1) == GET_CODE (p2)
1547 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
1548 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
1549 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
1550 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
1551 /* If the equivalences are not to a constant, they may
1552 reference pseudos that no longer exist, so we can't
1554 && CONSTANT_P (XEXP (equiv1, 0))
1555 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1557 rtx s1 = single_set (i1);
1558 rtx s2 = single_set (i2);
1559 if (s1 != 0 && s2 != 0
1560 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
1562 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
1563 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
1564 if (! rtx_renumbered_equal_p (p1, p2))
1566 else if (apply_change_group ())
1571 /* Insns fail to match; cross jumping is limited to the following
1575 /* Don't allow the insn after a compare to be shared by
1576 cross-jumping unless the compare is also shared.
1577 Here, if either of these non-matching insns is a compare,
1578 exclude the following insn from possible cross-jumping. */
1579 if (sets_cc0_p (p1) || sets_cc0_p (p2))
1580 last1 = afterlast1, last2 = afterlast2, ++minimum;
1583 /* If cross-jumping here will feed a jump-around-jump
1584 optimization, this jump won't cost extra, so reduce
1586 if (GET_CODE (i1) == JUMP_INSN
1588 && prev_real_insn (JUMP_LABEL (i1)) == e1)
1594 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
1596 /* Ok, this insn is potentially includable in a cross-jump here. */
1597 afterlast1 = last1, afterlast2 = last2;
1598 last1 = i1, last2 = i2, --minimum;
1602 if (minimum <= 0 && last1 != 0 && last1 != e1)
1603 *f1 = last1, *f2 = last2;
1607 do_cross_jump (insn, newjpos, newlpos)
1608 rtx insn, newjpos, newlpos;
1610 /* Find an existing label at this point
1611 or make a new one if there is none. */
1612 register rtx label = get_label_before (newlpos);
1614 /* Make the same jump insn jump to the new point. */
1615 if (GET_CODE (PATTERN (insn)) == RETURN)
1617 /* Remove from jump chain of returns. */
1618 delete_from_jump_chain (insn);
1619 /* Change the insn. */
1620 PATTERN (insn) = gen_jump (label);
1621 INSN_CODE (insn) = -1;
1622 JUMP_LABEL (insn) = label;
1623 LABEL_NUSES (label)++;
1624 /* Add to new the jump chain. */
1625 if (INSN_UID (label) < max_jump_chain
1626 && INSN_UID (insn) < max_jump_chain)
1628 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
1629 jump_chain[INSN_UID (label)] = insn;
1633 redirect_jump (insn, label, 1);
1635 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
1636 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
1637 the NEWJPOS stream. */
1639 while (newjpos != insn)
1643 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
1644 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
1645 || REG_NOTE_KIND (lnote) == REG_EQUIV)
1646 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
1647 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
1648 remove_note (newlpos, lnote);
1650 delete_insn (newjpos);
1651 newjpos = next_real_insn (newjpos);
1652 newlpos = next_real_insn (newlpos);
1656 /* Return the label before INSN, or put a new label there. */
1659 get_label_before (insn)
1664 /* Find an existing label at this point
1665 or make a new one if there is none. */
1666 label = prev_nonnote_insn (insn);
1668 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1670 rtx prev = PREV_INSN (insn);
1672 label = gen_label_rtx ();
1673 emit_label_after (label, prev);
1674 LABEL_NUSES (label) = 0;
1679 /* Return the label after INSN, or put a new label there. */
1682 get_label_after (insn)
1687 /* Find an existing label at this point
1688 or make a new one if there is none. */
1689 label = next_nonnote_insn (insn);
1691 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1693 label = gen_label_rtx ();
1694 emit_label_after (label, insn);
1695 LABEL_NUSES (label) = 0;
1700 /* Return 1 if INSN is a jump that jumps to right after TARGET
1701 only on the condition that TARGET itself would drop through.
1702 Assumes that TARGET is a conditional jump. */
1705 jump_back_p (insn, target)
1709 enum rtx_code codei, codet;
1711 if (simplejump_p (insn) || ! condjump_p (insn)
1712 || simplejump_p (target)
1713 || target != prev_real_insn (JUMP_LABEL (insn)))
1716 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
1717 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
1719 codei = GET_CODE (cinsn);
1720 codet = GET_CODE (ctarget);
1722 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
1724 if (! can_reverse_comparison_p (cinsn, insn))
1726 codei = reverse_condition (codei);
1729 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
1731 if (! can_reverse_comparison_p (ctarget, target))
1733 codet = reverse_condition (codet);
1736 return (codei == codet
1737 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
1738 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
1741 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
1742 return non-zero if it is safe to reverse this comparison. It is if our
1743 floating-point is not IEEE, if this is an NE or EQ comparison, or if
1744 this is known to be an integer comparison. */
1747 can_reverse_comparison_p (comparison, insn)
1753 /* If this is not actually a comparison, we can't reverse it. */
1754 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
1757 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
1758 /* If this is an NE comparison, it is safe to reverse it to an EQ
1759 comparison and vice versa, even for floating point. If no operands
1760 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
1761 always false and NE is always true, so the reversal is also valid. */
1763 || GET_CODE (comparison) == NE
1764 || GET_CODE (comparison) == EQ)
1767 arg0 = XEXP (comparison, 0);
1769 /* Make sure ARG0 is one of the actual objects being compared. If we
1770 can't do this, we can't be sure the comparison can be reversed.
1772 Handle cc0 and a MODE_CC register. */
1773 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
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)))
1795 for (prev = prev_nonnote_insn (insn);
1796 prev != 0 && GET_CODE (prev) != CODE_LABEL;
1797 prev = prev_nonnote_insn (prev))
1798 if ((set = single_set (prev)) != 0
1799 && rtx_equal_p (SET_DEST (set), arg0))
1801 arg0 = SET_SRC (set);
1803 if (GET_CODE (arg0) == COMPARE)
1804 arg0 = XEXP (arg0, 0);
1809 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
1810 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
1811 return (GET_CODE (arg0) == CONST_INT
1812 || (GET_MODE (arg0) != VOIDmode
1813 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
1814 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
1817 /* Given an rtx-code for a comparison, return the code for the negated
1818 comparison. If no such code exists, return UNKNOWN.
1820 WATCH OUT! reverse_condition is not safe to use on a jump that might
1821 be acting on the results of an IEEE floating point comparison, because
1822 of the special treatment of non-signaling nans in comparisons.
1823 Use can_reverse_comparison_p to be sure. */
1826 reverse_condition (code)
1869 /* Similar, but we're allowed to generate unordered comparisons, which
1870 makes it safe for IEEE floating-point. Of course, we have to recognize
1871 that the target will support them too... */
1874 reverse_condition_maybe_unordered (code)
1877 /* Non-IEEE formats don't have unordered conditions. */
1878 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
1879 return reverse_condition (code);
1925 /* Similar, but return the code when two operands of a comparison are swapped.
1926 This IS safe for IEEE floating-point. */
1929 swap_condition (code)
1972 /* Given a comparison CODE, return the corresponding unsigned comparison.
1973 If CODE is an equality comparison or already an unsigned comparison,
1974 CODE is returned. */
1977 unsigned_condition (code)
2004 /* Similarly, return the signed version of a comparison. */
2007 signed_condition (code)
2034 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2035 truth of CODE1 implies the truth of CODE2. */
2038 comparison_dominates_p (code1, code2)
2039 enum rtx_code code1, code2;
2047 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
2048 || code2 == ORDERED)
2053 if (code2 == LE || code2 == NE || code2 == ORDERED)
2058 if (code2 == GE || code2 == NE || code2 == ORDERED)
2064 if (code2 == ORDERED)
2069 if (code2 == NE || code2 == ORDERED)
2074 if (code2 == LEU || code2 == NE)
2079 if (code2 == GEU || code2 == NE)
2095 /* Return 1 if INSN is an unconditional jump and nothing else. */
2101 return (GET_CODE (insn) == JUMP_INSN
2102 && GET_CODE (PATTERN (insn)) == SET
2103 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2104 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2107 /* Return nonzero if INSN is a (possibly) conditional jump
2110 Use this function is deprecated, since we need to support combined
2111 branch and compare insns. Use any_condjump_p instead whenever possible. */
2117 register rtx x = PATTERN (insn);
2119 if (GET_CODE (x) != SET
2120 || GET_CODE (SET_DEST (x)) != PC)
2124 if (GET_CODE (x) == LABEL_REF)
2126 else return (GET_CODE (x) == IF_THEN_ELSE
2127 && ((GET_CODE (XEXP (x, 2)) == PC
2128 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
2129 || GET_CODE (XEXP (x, 1)) == RETURN))
2130 || (GET_CODE (XEXP (x, 1)) == PC
2131 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
2132 || GET_CODE (XEXP (x, 2)) == RETURN))));
2137 /* Return nonzero if INSN is a (possibly) conditional jump inside a
2140 Use this function is deprecated, since we need to support combined
2141 branch and compare insns. Use any_condjump_p instead whenever possible. */
2144 condjump_in_parallel_p (insn)
2147 register rtx x = PATTERN (insn);
2149 if (GET_CODE (x) != PARALLEL)
2152 x = XVECEXP (x, 0, 0);
2154 if (GET_CODE (x) != SET)
2156 if (GET_CODE (SET_DEST (x)) != PC)
2158 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2160 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2162 if (XEXP (SET_SRC (x), 2) == pc_rtx
2163 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2164 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2166 if (XEXP (SET_SRC (x), 1) == pc_rtx
2167 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2168 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2173 /* Return set of PC, otherwise NULL. */
2180 if (GET_CODE (insn) != JUMP_INSN)
2182 pat = PATTERN (insn);
2184 /* The set is allowed to appear either as the insn pattern or
2185 the first set in a PARALLEL. */
2186 if (GET_CODE (pat) == PARALLEL)
2187 pat = XVECEXP (pat, 0, 0);
2188 if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
2194 /* Return true when insn is an unconditional direct jump,
2195 possibly bundled inside a PARALLEL. */
2198 any_uncondjump_p (insn)
2201 rtx x = pc_set (insn);
2204 if (GET_CODE (SET_SRC (x)) != LABEL_REF)
2209 /* Return true when insn is a conditional jump. This function works for
2210 instructions containing PC sets in PARALLELs. The instruction may have
2211 various other effects so before removing the jump you must verify
2212 safe_to_remove_jump_p.
2214 Note that unlike condjump_p it returns false for unconditional jumps. */
2217 any_condjump_p (insn)
2220 rtx x = pc_set (insn);
2225 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2228 a = GET_CODE (XEXP (SET_SRC (x), 1));
2229 b = GET_CODE (XEXP (SET_SRC (x), 2));
2231 return ((b == PC && (a == LABEL_REF || a == RETURN))
2232 || (a == PC && (b == LABEL_REF || b == RETURN)));
2235 /* Return the label of a conditional jump. */
2238 condjump_label (insn)
2241 rtx x = pc_set (insn);
2246 if (GET_CODE (x) == LABEL_REF)
2248 if (GET_CODE (x) != IF_THEN_ELSE)
2250 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
2252 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
2257 /* Return true if INSN is a (possibly conditional) return insn. */
2260 returnjump_p_1 (loc, data)
2262 void *data ATTRIBUTE_UNUSED;
2265 return x && GET_CODE (x) == RETURN;
2272 if (GET_CODE (insn) != JUMP_INSN)
2274 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
2277 /* Return true if INSN is a jump that only transfers control and
2286 if (GET_CODE (insn) != JUMP_INSN)
2289 set = single_set (insn);
2292 if (GET_CODE (SET_DEST (set)) != PC)
2294 if (side_effects_p (SET_SRC (set)))
2302 /* Return 1 if X is an RTX that does nothing but set the condition codes
2303 and CLOBBER or USE registers.
2304 Return -1 if X does explicitly set the condition codes,
2305 but also does other things. */
2309 rtx x ATTRIBUTE_UNUSED;
2311 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2313 if (GET_CODE (x) == PARALLEL)
2317 int other_things = 0;
2318 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2320 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2321 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2323 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2326 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2332 /* Follow any unconditional jump at LABEL;
2333 return the ultimate label reached by any such chain of jumps.
2334 If LABEL is not followed by a jump, return LABEL.
2335 If the chain loops or we can't find end, return LABEL,
2336 since that tells caller to avoid changing the insn.
2338 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2339 a USE or CLOBBER. */
2342 follow_jumps (label)
2347 register rtx value = label;
2352 && (insn = next_active_insn (value)) != 0
2353 && GET_CODE (insn) == JUMP_INSN
2354 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2355 || GET_CODE (PATTERN (insn)) == RETURN)
2356 && (next = NEXT_INSN (insn))
2357 && GET_CODE (next) == BARRIER);
2360 /* Don't chain through the insn that jumps into a loop
2361 from outside the loop,
2362 since that would create multiple loop entry jumps
2363 and prevent loop optimization. */
2365 if (!reload_completed)
2366 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2367 if (GET_CODE (tem) == NOTE
2368 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
2369 /* ??? Optional. Disables some optimizations, but makes
2370 gcov output more accurate with -O. */
2371 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
2374 /* If we have found a cycle, make the insn jump to itself. */
2375 if (JUMP_LABEL (insn) == label)
2378 tem = next_active_insn (JUMP_LABEL (insn));
2379 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
2380 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
2383 value = JUMP_LABEL (insn);
2390 /* Assuming that field IDX of X is a vector of label_refs,
2391 replace each of them by the ultimate label reached by it.
2392 Return nonzero if a change is made.
2393 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2396 tension_vector_labels (x, idx)
2402 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2404 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2405 register rtx nlabel = follow_jumps (olabel);
2406 if (nlabel && nlabel != olabel)
2408 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2409 ++LABEL_NUSES (nlabel);
2410 if (--LABEL_NUSES (olabel) == 0)
2411 delete_insn (olabel);
2418 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2419 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2420 in INSN, then store one of them in JUMP_LABEL (INSN).
2421 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2422 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2423 Also, when there are consecutive labels, canonicalize on the last of them.
2425 Note that two labels separated by a loop-beginning note
2426 must be kept distinct if we have not yet done loop-optimization,
2427 because the gap between them is where loop-optimize
2428 will want to move invariant code to. CROSS_JUMP tells us
2429 that loop-optimization is done with.
2431 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2432 two labels distinct if they are separated by only USE or CLOBBER insns. */
2435 mark_jump_label (x, insn, cross_jump, in_mem)
2441 register RTX_CODE code = GET_CODE (x);
2443 register const char *fmt;
2465 /* If this is a constant-pool reference, see if it is a label. */
2466 if (CONSTANT_POOL_ADDRESS_P (x))
2467 mark_jump_label (get_pool_constant (x), insn, cross_jump, in_mem);
2472 rtx label = XEXP (x, 0);
2477 /* Ignore remaining references to unreachable labels that
2478 have been deleted. */
2479 if (GET_CODE (label) == NOTE
2480 && NOTE_LINE_NUMBER (label) == NOTE_INSN_DELETED_LABEL)
2483 if (GET_CODE (label) != CODE_LABEL)
2486 /* Ignore references to labels of containing functions. */
2487 if (LABEL_REF_NONLOCAL_P (x))
2490 /* If there are other labels following this one,
2491 replace it with the last of the consecutive labels. */
2492 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
2494 if (GET_CODE (next) == CODE_LABEL)
2496 else if (cross_jump && GET_CODE (next) == INSN
2497 && (GET_CODE (PATTERN (next)) == USE
2498 || GET_CODE (PATTERN (next)) == CLOBBER))
2500 else if (GET_CODE (next) != NOTE)
2502 else if (! cross_jump
2503 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
2504 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
2505 /* ??? Optional. Disables some optimizations, but
2506 makes gcov output more accurate with -O. */
2507 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
2511 XEXP (x, 0) = label;
2512 if (! insn || ! INSN_DELETED_P (insn))
2513 ++LABEL_NUSES (label);
2517 if (GET_CODE (insn) == JUMP_INSN)
2518 JUMP_LABEL (insn) = label;
2520 /* If we've changed OLABEL and we had a REG_LABEL note
2521 for it, update it as well. */
2522 else if (label != olabel
2523 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
2524 XEXP (note, 0) = label;
2526 /* Otherwise, add a REG_LABEL note for LABEL unless there already
2528 else if (! find_reg_note (insn, REG_LABEL, label))
2530 /* This code used to ignore labels which refered to dispatch
2531 tables to avoid flow.c generating worse code.
2533 However, in the presense of global optimizations like
2534 gcse which call find_basic_blocks without calling
2535 life_analysis, not recording such labels will lead
2536 to compiler aborts because of inconsistencies in the
2537 flow graph. So we go ahead and record the label.
2539 It may also be the case that the optimization argument
2540 is no longer valid because of the more accurate cfg
2541 we build in find_basic_blocks -- it no longer pessimizes
2542 code when it finds a REG_LABEL note. */
2543 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
2550 /* Do walk the labels in a vector, but not the first operand of an
2551 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2554 if (! INSN_DELETED_P (insn))
2556 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
2558 for (i = 0; i < XVECLEN (x, eltnum); i++)
2559 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX,
2560 cross_jump, in_mem);
2568 fmt = GET_RTX_FORMAT (code);
2569 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2572 mark_jump_label (XEXP (x, i), insn, cross_jump, in_mem);
2573 else if (fmt[i] == 'E')
2576 for (j = 0; j < XVECLEN (x, i); j++)
2577 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump, in_mem);
2582 /* If all INSN does is set the pc, delete it,
2583 and delete the insn that set the condition codes for it
2584 if that's what the previous thing was. */
2590 register rtx set = single_set (insn);
2592 if (set && GET_CODE (SET_DEST (set)) == PC)
2593 delete_computation (insn);
2596 /* Verify INSN is a BARRIER and delete it. */
2599 delete_barrier (insn)
2602 if (GET_CODE (insn) != BARRIER)
2608 /* Recursively delete prior insns that compute the value (used only by INSN
2609 which the caller is deleting) stored in the register mentioned by NOTE
2610 which is a REG_DEAD note associated with INSN. */
2613 delete_prior_computation (note, insn)
2618 rtx reg = XEXP (note, 0);
2620 for (our_prev = prev_nonnote_insn (insn);
2621 our_prev && (GET_CODE (our_prev) == INSN
2622 || GET_CODE (our_prev) == CALL_INSN);
2623 our_prev = prev_nonnote_insn (our_prev))
2625 rtx pat = PATTERN (our_prev);
2627 /* If we reach a CALL which is not calling a const function
2628 or the callee pops the arguments, then give up. */
2629 if (GET_CODE (our_prev) == CALL_INSN
2630 && (! CONST_CALL_P (our_prev)
2631 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
2634 /* If we reach a SEQUENCE, it is too complex to try to
2635 do anything with it, so give up. */
2636 if (GET_CODE (pat) == SEQUENCE)
2639 if (GET_CODE (pat) == USE
2640 && GET_CODE (XEXP (pat, 0)) == INSN)
2641 /* reorg creates USEs that look like this. We leave them
2642 alone because reorg needs them for its own purposes. */
2645 if (reg_set_p (reg, pat))
2647 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
2650 if (GET_CODE (pat) == PARALLEL)
2652 /* If we find a SET of something else, we can't
2657 for (i = 0; i < XVECLEN (pat, 0); i++)
2659 rtx part = XVECEXP (pat, 0, i);
2661 if (GET_CODE (part) == SET
2662 && SET_DEST (part) != reg)
2666 if (i == XVECLEN (pat, 0))
2667 delete_computation (our_prev);
2669 else if (GET_CODE (pat) == SET
2670 && GET_CODE (SET_DEST (pat)) == REG)
2672 int dest_regno = REGNO (SET_DEST (pat));
2674 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
2675 ? HARD_REGNO_NREGS (dest_regno,
2676 GET_MODE (SET_DEST (pat))) : 1);
2677 int regno = REGNO (reg);
2678 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
2679 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
2681 if (dest_regno >= regno
2682 && dest_endregno <= endregno)
2683 delete_computation (our_prev);
2685 /* We may have a multi-word hard register and some, but not
2686 all, of the words of the register are needed in subsequent
2687 insns. Write REG_UNUSED notes for those parts that were not
2689 else if (dest_regno <= regno
2690 && dest_endregno >= endregno)
2694 REG_NOTES (our_prev)
2695 = gen_rtx_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (our_prev));
2697 for (i = dest_regno; i < dest_endregno; i++)
2698 if (! find_regno_note (our_prev, REG_UNUSED, i))
2701 if (i == dest_endregno)
2702 delete_computation (our_prev);
2709 /* If PAT references the register that dies here, it is an
2710 additional use. Hence any prior SET isn't dead. However, this
2711 insn becomes the new place for the REG_DEAD note. */
2712 if (reg_overlap_mentioned_p (reg, pat))
2714 XEXP (note, 1) = REG_NOTES (our_prev);
2715 REG_NOTES (our_prev) = note;
2721 /* Delete INSN and recursively delete insns that compute values used only
2722 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2723 If we are running before flow.c, we need do nothing since flow.c will
2724 delete dead code. We also can't know if the registers being used are
2725 dead or not at this point.
2727 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2728 nothing other than set a register that dies in this insn, we can delete
2731 On machines with CC0, if CC0 is used in this insn, we may be able to
2732 delete the insn that set it. */
2735 delete_computation (insn)
2742 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
2744 rtx prev = prev_nonnote_insn (insn);
2745 /* We assume that at this stage
2746 CC's are always set explicitly
2747 and always immediately before the jump that
2748 will use them. So if the previous insn
2749 exists to set the CC's, delete it
2750 (unless it performs auto-increments, etc.). */
2751 if (prev && GET_CODE (prev) == INSN
2752 && sets_cc0_p (PATTERN (prev)))
2754 if (sets_cc0_p (PATTERN (prev)) > 0
2755 && ! side_effects_p (PATTERN (prev)))
2756 delete_computation (prev);
2758 /* Otherwise, show that cc0 won't be used. */
2759 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
2760 cc0_rtx, REG_NOTES (prev));
2765 #ifdef INSN_SCHEDULING
2766 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
2767 reload has completed. The schedulers need to be fixed. Until
2768 they are, we must not rely on the death notes here. */
2769 if (reload_completed && flag_schedule_insns_after_reload)
2776 /* The REG_DEAD note may have been omitted for a register
2777 which is both set and used by the insn. */
2778 set = single_set (insn);
2779 if (set && GET_CODE (SET_DEST (set)) == REG)
2781 int dest_regno = REGNO (SET_DEST (set));
2783 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
2784 ? HARD_REGNO_NREGS (dest_regno,
2785 GET_MODE (SET_DEST (set))) : 1);
2788 for (i = dest_regno; i < dest_endregno; i++)
2790 if (! refers_to_regno_p (i, i + 1, SET_SRC (set), NULL_PTR)
2791 || find_regno_note (insn, REG_DEAD, i))
2794 note = gen_rtx_EXPR_LIST (REG_DEAD, (i < FIRST_PSEUDO_REGISTER
2795 ? gen_rtx_REG (reg_raw_mode[i], i)
2796 : SET_DEST (set)), NULL_RTX);
2797 delete_prior_computation (note, insn);
2801 for (note = REG_NOTES (insn); note; note = next)
2803 next = XEXP (note, 1);
2805 if (REG_NOTE_KIND (note) != REG_DEAD
2806 /* Verify that the REG_NOTE is legitimate. */
2807 || GET_CODE (XEXP (note, 0)) != REG)
2810 delete_prior_computation (note, insn);
2816 /* Delete insn INSN from the chain of insns and update label ref counts.
2817 May delete some following insns as a consequence; may even delete
2818 a label elsewhere and insns that follow it.
2820 Returns the first insn after INSN that was not deleted. */
2826 register rtx next = NEXT_INSN (insn);
2827 register rtx prev = PREV_INSN (insn);
2828 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
2829 register int dont_really_delete = 0;
2831 while (next && INSN_DELETED_P (next))
2832 next = NEXT_INSN (next);
2834 /* This insn is already deleted => return first following nondeleted. */
2835 if (INSN_DELETED_P (insn))
2839 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2841 /* Don't delete user-declared labels. When optimizing, convert them
2842 to special NOTEs instead. When not optimizing, leave them alone. */
2843 if (was_code_label && LABEL_NAME (insn) != 0)
2846 dont_really_delete = 1;
2847 else if (! dont_really_delete)
2849 const char *name = LABEL_NAME (insn);
2850 PUT_CODE (insn, NOTE);
2851 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
2852 NOTE_SOURCE_FILE (insn) = name;
2853 dont_really_delete = 1;
2857 /* Mark this insn as deleted. */
2858 INSN_DELETED_P (insn) = 1;
2860 /* If this is an unconditional jump, delete it from the jump chain. */
2861 if (simplejump_p (insn))
2862 delete_from_jump_chain (insn);
2864 /* If instruction is followed by a barrier,
2865 delete the barrier too. */
2867 if (next != 0 && GET_CODE (next) == BARRIER)
2869 INSN_DELETED_P (next) = 1;
2870 next = NEXT_INSN (next);
2873 /* Patch out INSN (and the barrier if any) */
2875 if (! dont_really_delete)
2879 NEXT_INSN (prev) = next;
2880 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
2881 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
2882 XVECLEN (PATTERN (prev), 0) - 1)) = next;
2887 PREV_INSN (next) = prev;
2888 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
2889 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
2892 if (prev && NEXT_INSN (prev) == 0)
2893 set_last_insn (prev);
2896 /* If deleting a jump, decrement the count of the label,
2897 and delete the label if it is now unused. */
2899 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
2901 rtx lab = JUMP_LABEL (insn), lab_next;
2903 if (--LABEL_NUSES (lab) == 0)
2905 /* This can delete NEXT or PREV,
2906 either directly if NEXT is JUMP_LABEL (INSN),
2907 or indirectly through more levels of jumps. */
2910 /* I feel a little doubtful about this loop,
2911 but I see no clean and sure alternative way
2912 to find the first insn after INSN that is not now deleted.
2913 I hope this works. */
2914 while (next && INSN_DELETED_P (next))
2915 next = NEXT_INSN (next);
2918 else if ((lab_next = next_nonnote_insn (lab)) != NULL
2919 && GET_CODE (lab_next) == JUMP_INSN
2920 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
2921 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
2923 /* If we're deleting the tablejump, delete the dispatch table.
2924 We may not be able to kill the label immediately preceeding
2925 just yet, as it might be referenced in code leading up to
2927 delete_insn (lab_next);
2931 /* Likewise if we're deleting a dispatch table. */
2933 if (GET_CODE (insn) == JUMP_INSN
2934 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2935 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2937 rtx pat = PATTERN (insn);
2938 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2939 int len = XVECLEN (pat, diff_vec_p);
2941 for (i = 0; i < len; i++)
2942 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
2943 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
2944 while (next && INSN_DELETED_P (next))
2945 next = NEXT_INSN (next);
2949 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
2950 prev = PREV_INSN (prev);
2952 /* If INSN was a label and a dispatch table follows it,
2953 delete the dispatch table. The tablejump must have gone already.
2954 It isn't useful to fall through into a table. */
2957 && NEXT_INSN (insn) != 0
2958 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
2959 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
2960 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
2961 next = delete_insn (NEXT_INSN (insn));
2963 /* If INSN was a label, delete insns following it if now unreachable. */
2965 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
2967 register RTX_CODE code;
2969 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
2970 || code == NOTE || code == BARRIER
2971 || (code == CODE_LABEL && INSN_DELETED_P (next))))
2974 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
2975 next = NEXT_INSN (next);
2976 /* Keep going past other deleted labels to delete what follows. */
2977 else if (code == CODE_LABEL && INSN_DELETED_P (next))
2978 next = NEXT_INSN (next);
2980 /* Note: if this deletes a jump, it can cause more
2981 deletion of unreachable code, after a different label.
2982 As long as the value from this recursive call is correct,
2983 this invocation functions correctly. */
2984 next = delete_insn (next);
2991 /* Advance from INSN till reaching something not deleted
2992 then return that. May return INSN itself. */
2995 next_nondeleted_insn (insn)
2998 while (INSN_DELETED_P (insn))
2999 insn = NEXT_INSN (insn);
3003 /* Delete a range of insns from FROM to TO, inclusive.
3004 This is for the sake of peephole optimization, so assume
3005 that whatever these insns do will still be done by a new
3006 peephole insn that will replace them. */
3009 delete_for_peephole (from, to)
3010 register rtx from, to;
3012 register rtx insn = from;
3016 register rtx next = NEXT_INSN (insn);
3017 register rtx prev = PREV_INSN (insn);
3019 if (GET_CODE (insn) != NOTE)
3021 INSN_DELETED_P (insn) = 1;
3023 /* Patch this insn out of the chain. */
3024 /* We don't do this all at once, because we
3025 must preserve all NOTEs. */
3027 NEXT_INSN (prev) = next;
3030 PREV_INSN (next) = prev;
3038 /* Note that if TO is an unconditional jump
3039 we *do not* delete the BARRIER that follows,
3040 since the peephole that replaces this sequence
3041 is also an unconditional jump in that case. */
3044 /* We have determined that INSN is never reached, and are about to
3045 delete it. Print a warning if the user asked for one.
3047 To try to make this warning more useful, this should only be called
3048 once per basic block not reached, and it only warns when the basic
3049 block contains more than one line from the current function, and
3050 contains at least one operation. CSE and inlining can duplicate insns,
3051 so it's possible to get spurious warnings from this. */
3054 never_reached_warning (avoided_insn)
3058 rtx a_line_note = NULL;
3059 int two_avoided_lines = 0;
3060 int contains_insn = 0;
3062 if (! warn_notreached)
3065 /* Scan forwards, looking at LINE_NUMBER notes, until
3066 we hit a LABEL or we run out of insns. */
3068 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
3070 if (GET_CODE (insn) == CODE_LABEL)
3072 else if (GET_CODE (insn) == NOTE /* A line number note? */
3073 && NOTE_LINE_NUMBER (insn) >= 0)
3075 if (a_line_note == NULL)
3078 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
3079 != NOTE_LINE_NUMBER (insn));
3081 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
3084 if (two_avoided_lines && contains_insn)
3085 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
3086 NOTE_LINE_NUMBER (a_line_note),
3087 "will never be executed");
3090 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
3091 NLABEL as a return. Accrue modifications into the change group. */
3094 redirect_exp_1 (loc, olabel, nlabel, insn)
3099 register rtx x = *loc;
3100 register RTX_CODE code = GET_CODE (x);
3102 register const char *fmt;
3104 if (code == LABEL_REF)
3106 if (XEXP (x, 0) == olabel)
3110 n = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3112 n = gen_rtx_RETURN (VOIDmode);
3114 validate_change (insn, loc, n, 1);
3118 else if (code == RETURN && olabel == 0)
3120 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3121 if (loc == &PATTERN (insn))
3122 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
3123 validate_change (insn, loc, x, 1);
3127 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3128 && GET_CODE (SET_SRC (x)) == LABEL_REF
3129 && XEXP (SET_SRC (x), 0) == olabel)
3131 validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 1);
3135 fmt = GET_RTX_FORMAT (code);
3136 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3139 redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
3140 else if (fmt[i] == 'E')
3143 for (j = 0; j < XVECLEN (x, i); j++)
3144 redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
3149 /* Similar, but apply the change group and report success or failure. */
3152 redirect_exp (loc, olabel, nlabel, insn)
3157 redirect_exp_1 (loc, olabel, nlabel, insn);
3158 if (num_validated_changes () == 0)
3161 return apply_change_group ();
3164 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
3165 the modifications into the change group. Return false if we did
3166 not see how to do that. */
3169 redirect_jump_1 (jump, nlabel)
3172 int ochanges = num_validated_changes ();
3173 redirect_exp_1 (&PATTERN (jump), JUMP_LABEL (jump), nlabel, jump);
3174 return num_validated_changes () > ochanges;
3177 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
3178 jump target label is unused as a result, it and the code following
3181 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3184 The return value will be 1 if the change was made, 0 if it wasn't
3185 (this can only occur for NLABEL == 0). */
3188 redirect_jump (jump, nlabel, delete_unused)
3192 register rtx olabel = JUMP_LABEL (jump);
3194 if (nlabel == olabel)
3197 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3200 /* If this is an unconditional branch, delete it from the jump_chain of
3201 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3202 have UID's in range and JUMP_CHAIN is valid). */
3203 if (jump_chain && (simplejump_p (jump)
3204 || GET_CODE (PATTERN (jump)) == RETURN))
3206 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3208 delete_from_jump_chain (jump);
3209 if (label_index < max_jump_chain
3210 && INSN_UID (jump) < max_jump_chain)
3212 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3213 jump_chain[label_index] = jump;
3217 JUMP_LABEL (jump) = nlabel;
3219 ++LABEL_NUSES (nlabel);
3221 /* If we're eliding the jump over exception cleanups at the end of a
3222 function, move the function end note so that -Wreturn-type works. */
3223 if (olabel && NEXT_INSN (olabel)
3224 && GET_CODE (NEXT_INSN (olabel)) == NOTE
3225 && NOTE_LINE_NUMBER (NEXT_INSN (olabel)) == NOTE_INSN_FUNCTION_END)
3226 emit_note_after (NOTE_INSN_FUNCTION_END, nlabel);
3228 if (olabel && --LABEL_NUSES (olabel) == 0 && delete_unused)
3229 delete_insn (olabel);
3234 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3235 Accrue the modifications into the change group. */
3238 invert_exp_1 (x, insn)
3242 register RTX_CODE code;
3244 register const char *fmt;
3246 code = GET_CODE (x);
3248 if (code == IF_THEN_ELSE)
3250 register rtx comp = XEXP (x, 0);
3253 /* We can do this in two ways: The preferable way, which can only
3254 be done if this is not an integer comparison, is to reverse
3255 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3256 of the IF_THEN_ELSE. If we can't do either, fail. */
3258 if (can_reverse_comparison_p (comp, insn))
3260 validate_change (insn, &XEXP (x, 0),
3261 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
3262 GET_MODE (comp), XEXP (comp, 0),
3269 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3270 validate_change (insn, &XEXP (x, 2), tem, 1);
3274 fmt = GET_RTX_FORMAT (code);
3275 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3278 invert_exp_1 (XEXP (x, i), insn);
3279 else if (fmt[i] == 'E')
3282 for (j = 0; j < XVECLEN (x, i); j++)
3283 invert_exp_1 (XVECEXP (x, i, j), insn);
3288 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3290 Return 1 if we can do so, 0 if we cannot find a way to do so that
3291 matches a pattern. */
3294 invert_exp (x, insn)
3298 invert_exp_1 (x, insn);
3299 if (num_validated_changes () == 0)
3302 return apply_change_group ();
3305 /* Invert the condition of the jump JUMP, and make it jump to label
3306 NLABEL instead of where it jumps now. Accrue changes into the
3307 change group. Return false if we didn't see how to perform the
3308 inversion and redirection. */
3311 invert_jump_1 (jump, nlabel)
3316 ochanges = num_validated_changes ();
3317 invert_exp_1 (PATTERN (jump), jump);
3318 if (num_validated_changes () == ochanges)
3321 return redirect_jump_1 (jump, nlabel);
3324 /* Invert the condition of the jump JUMP, and make it jump to label
3325 NLABEL instead of where it jumps now. Return true if successful. */
3328 invert_jump (jump, nlabel, delete_unused)
3332 /* We have to either invert the condition and change the label or
3333 do neither. Either operation could fail. We first try to invert
3334 the jump. If that succeeds, we try changing the label. If that fails,
3335 we invert the jump back to what it was. */
3337 if (! invert_exp (PATTERN (jump), jump))
3340 if (redirect_jump (jump, nlabel, delete_unused))
3342 /* An inverted jump means that a probability taken becomes a
3343 probability not taken. Subtract the branch probability from the
3344 probability base to convert it back to a taken probability. */
3346 rtx note = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3348 XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
3353 if (! invert_exp (PATTERN (jump), jump))
3354 /* This should just be putting it back the way it was. */
3360 /* Delete the instruction JUMP from any jump chain it might be on. */
3363 delete_from_jump_chain (jump)
3367 rtx olabel = JUMP_LABEL (jump);
3369 /* Handle unconditional jumps. */
3370 if (jump_chain && olabel != 0
3371 && INSN_UID (olabel) < max_jump_chain
3372 && simplejump_p (jump))
3373 index = INSN_UID (olabel);
3374 /* Handle return insns. */
3375 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3379 if (jump_chain[index] == jump)
3380 jump_chain[index] = jump_chain[INSN_UID (jump)];
3385 for (insn = jump_chain[index];
3387 insn = jump_chain[INSN_UID (insn)])
3388 if (jump_chain[INSN_UID (insn)] == jump)
3390 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3396 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3398 If the old jump target label (before the dispatch table) becomes unused,
3399 it and the dispatch table may be deleted. In that case, find the insn
3400 before the jump references that label and delete it and logical successors
3404 redirect_tablejump (jump, nlabel)
3407 register rtx olabel = JUMP_LABEL (jump);
3409 /* Add this jump to the jump_chain of NLABEL. */
3410 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3411 && INSN_UID (jump) < max_jump_chain)
3413 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3414 jump_chain[INSN_UID (nlabel)] = jump;
3417 PATTERN (jump) = gen_jump (nlabel);
3418 JUMP_LABEL (jump) = nlabel;
3419 ++LABEL_NUSES (nlabel);
3420 INSN_CODE (jump) = -1;
3422 if (--LABEL_NUSES (olabel) == 0)
3424 delete_labelref_insn (jump, olabel, 0);
3425 delete_insn (olabel);
3429 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3430 If we found one, delete it and then delete this insn if DELETE_THIS is
3431 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3434 delete_labelref_insn (insn, label, delete_this)
3441 if (GET_CODE (insn) != NOTE
3442 && reg_mentioned_p (label, PATTERN (insn)))
3453 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3454 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3468 /* Like rtx_equal_p except that it considers two REGs as equal
3469 if they renumber to the same value and considers two commutative
3470 operations to be the same if the order of the operands has been
3473 ??? Addition is not commutative on the PA due to the weird implicit
3474 space register selection rules for memory addresses. Therefore, we
3475 don't consider a + b == b + a.
3477 We could/should make this test a little tighter. Possibly only
3478 disabling it on the PA via some backend macro or only disabling this
3479 case when the PLUS is inside a MEM. */
3482 rtx_renumbered_equal_p (x, y)
3486 register RTX_CODE code = GET_CODE (x);
3487 register const char *fmt;
3492 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3493 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3494 && GET_CODE (SUBREG_REG (y)) == REG)))
3496 int reg_x = -1, reg_y = -1;
3497 int word_x = 0, word_y = 0;
3499 if (GET_MODE (x) != GET_MODE (y))
3502 /* If we haven't done any renumbering, don't
3503 make any assumptions. */
3504 if (reg_renumber == 0)
3505 return rtx_equal_p (x, y);
3509 reg_x = REGNO (SUBREG_REG (x));
3510 word_x = SUBREG_WORD (x);
3512 if (reg_renumber[reg_x] >= 0)
3514 reg_x = reg_renumber[reg_x] + word_x;
3522 if (reg_renumber[reg_x] >= 0)
3523 reg_x = reg_renumber[reg_x];
3526 if (GET_CODE (y) == SUBREG)
3528 reg_y = REGNO (SUBREG_REG (y));
3529 word_y = SUBREG_WORD (y);
3531 if (reg_renumber[reg_y] >= 0)
3533 reg_y = reg_renumber[reg_y];
3541 if (reg_renumber[reg_y] >= 0)
3542 reg_y = reg_renumber[reg_y];
3545 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3548 /* Now we have disposed of all the cases
3549 in which different rtx codes can match. */
3550 if (code != GET_CODE (y))
3562 return INTVAL (x) == INTVAL (y);
3565 /* We can't assume nonlocal labels have their following insns yet. */
3566 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3567 return XEXP (x, 0) == XEXP (y, 0);
3569 /* Two label-refs are equivalent if they point at labels
3570 in the same position in the instruction stream. */
3571 return (next_real_insn (XEXP (x, 0))
3572 == next_real_insn (XEXP (y, 0)));
3575 return XSTR (x, 0) == XSTR (y, 0);
3578 /* If we didn't match EQ equality above, they aren't the same. */
3585 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3587 if (GET_MODE (x) != GET_MODE (y))
3590 /* For commutative operations, the RTX match if the operand match in any
3591 order. Also handle the simple binary and unary cases without a loop.
3593 ??? Don't consider PLUS a commutative operator; see comments above. */
3594 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3596 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3597 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
3598 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
3599 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
3600 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3601 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3602 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
3603 else if (GET_RTX_CLASS (code) == '1')
3604 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
3606 /* Compare the elements. If any pair of corresponding elements
3607 fail to match, return 0 for the whole things. */
3609 fmt = GET_RTX_FORMAT (code);
3610 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3616 if (XWINT (x, i) != XWINT (y, i))
3621 if (XINT (x, i) != XINT (y, i))
3626 if (strcmp (XSTR (x, i), XSTR (y, i)))
3631 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3636 if (XEXP (x, i) != XEXP (y, i))
3643 if (XVECLEN (x, i) != XVECLEN (y, i))
3645 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3646 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3657 /* If X is a hard register or equivalent to one or a subregister of one,
3658 return the hard register number. If X is a pseudo register that was not
3659 assigned a hard register, return the pseudo register number. Otherwise,
3660 return -1. Any rtx is valid for X. */
3666 if (GET_CODE (x) == REG)
3668 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3669 return reg_renumber[REGNO (x)];
3672 if (GET_CODE (x) == SUBREG)
3674 int base = true_regnum (SUBREG_REG (x));
3675 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3676 return SUBREG_WORD (x) + base;
3681 /* Optimize code of the form:
3683 for (x = a[i]; x; ...)
3685 for (x = a[i]; x; ...)
3689 Loop optimize will change the above code into
3693 { ...; if (! (x = ...)) break; }
3696 { ...; if (! (x = ...)) break; }
3699 In general, if the first test fails, the program can branch
3700 directly to `foo' and skip the second try which is doomed to fail.
3701 We run this after loop optimization and before flow analysis. */
3703 /* When comparing the insn patterns, we track the fact that different
3704 pseudo-register numbers may have been used in each computation.
3705 The following array stores an equivalence -- same_regs[I] == J means
3706 that pseudo register I was used in the first set of tests in a context
3707 where J was used in the second set. We also count the number of such
3708 pending equivalences. If nonzero, the expressions really aren't the
3711 static int *same_regs;
3713 static int num_same_regs;
3715 /* Track any registers modified between the target of the first jump and
3716 the second jump. They never compare equal. */
3718 static char *modified_regs;
3720 /* Record if memory was modified. */
3722 static int modified_mem;
3724 /* Called via note_stores on each insn between the target of the first
3725 branch and the second branch. It marks any changed registers. */
3728 mark_modified_reg (dest, x, data)
3730 rtx x ATTRIBUTE_UNUSED;
3731 void *data ATTRIBUTE_UNUSED;
3736 if (GET_CODE (dest) == SUBREG)
3737 dest = SUBREG_REG (dest);
3739 if (GET_CODE (dest) == MEM)
3742 if (GET_CODE (dest) != REG)
3745 regno = REGNO (dest);
3746 if (regno >= FIRST_PSEUDO_REGISTER)
3747 modified_regs[regno] = 1;
3749 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3750 modified_regs[regno + i] = 1;
3753 /* F is the first insn in the chain of insns. */
3756 thread_jumps (f, max_reg, flag_before_loop)
3759 int flag_before_loop;
3761 /* Basic algorithm is to find a conditional branch,
3762 the label it may branch to, and the branch after
3763 that label. If the two branches test the same condition,
3764 walk back from both branch paths until the insn patterns
3765 differ, or code labels are hit. If we make it back to
3766 the target of the first branch, then we know that the first branch
3767 will either always succeed or always fail depending on the relative
3768 senses of the two branches. So adjust the first branch accordingly
3771 rtx label, b1, b2, t1, t2;
3772 enum rtx_code code1, code2;
3773 rtx b1op0, b1op1, b2op0, b2op1;
3778 /* Allocate register tables and quick-reset table. */
3779 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
3780 same_regs = (int *) xmalloc (max_reg * sizeof (int));
3781 all_reset = (int *) xmalloc (max_reg * sizeof (int));
3782 for (i = 0; i < max_reg; i++)
3789 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3791 /* Get to a candidate branch insn. */
3792 if (GET_CODE (b1) != JUMP_INSN
3793 || ! condjump_p (b1) || simplejump_p (b1)
3794 || JUMP_LABEL (b1) == 0)
3797 bzero (modified_regs, max_reg * sizeof (char));
3800 bcopy ((char *) all_reset, (char *) same_regs,
3801 max_reg * sizeof (int));
3804 label = JUMP_LABEL (b1);
3806 /* Look for a branch after the target. Record any registers and
3807 memory modified between the target and the branch. Stop when we
3808 get to a label since we can't know what was changed there. */
3809 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
3811 if (GET_CODE (b2) == CODE_LABEL)
3814 else if (GET_CODE (b2) == JUMP_INSN)
3816 /* If this is an unconditional jump and is the only use of
3817 its target label, we can follow it. */
3818 if (simplejump_p (b2)
3819 && JUMP_LABEL (b2) != 0
3820 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
3822 b2 = JUMP_LABEL (b2);
3829 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
3832 if (GET_CODE (b2) == CALL_INSN)
3835 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3836 if (call_used_regs[i] && ! fixed_regs[i]
3837 && i != STACK_POINTER_REGNUM
3838 && i != FRAME_POINTER_REGNUM
3839 && i != HARD_FRAME_POINTER_REGNUM
3840 && i != ARG_POINTER_REGNUM)
3841 modified_regs[i] = 1;
3844 note_stores (PATTERN (b2), mark_modified_reg, NULL);
3847 /* Check the next candidate branch insn from the label
3850 || GET_CODE (b2) != JUMP_INSN
3852 || ! condjump_p (b2)
3853 || simplejump_p (b2))
3856 /* Get the comparison codes and operands, reversing the
3857 codes if appropriate. If we don't have comparison codes,
3858 we can't do anything. */
3859 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
3860 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
3861 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
3862 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
3863 code1 = reverse_condition (code1);
3865 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
3866 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
3867 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
3868 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
3869 code2 = reverse_condition (code2);
3871 /* If they test the same things and knowing that B1 branches
3872 tells us whether or not B2 branches, check if we
3873 can thread the branch. */
3874 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
3875 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
3876 && (comparison_dominates_p (code1, code2)
3877 || (can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
3880 && comparison_dominates_p (code1, reverse_condition (code2)))))
3883 t1 = prev_nonnote_insn (b1);
3884 t2 = prev_nonnote_insn (b2);
3886 while (t1 != 0 && t2 != 0)
3890 /* We have reached the target of the first branch.
3891 If there are no pending register equivalents,
3892 we know that this branch will either always
3893 succeed (if the senses of the two branches are
3894 the same) or always fail (if not). */
3897 if (num_same_regs != 0)
3900 if (comparison_dominates_p (code1, code2))
3901 new_label = JUMP_LABEL (b2);
3903 new_label = get_label_after (b2);
3905 if (JUMP_LABEL (b1) != new_label)
3907 rtx prev = PREV_INSN (new_label);
3909 if (flag_before_loop
3910 && GET_CODE (prev) == NOTE
3911 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
3913 /* Don't thread to the loop label. If a loop
3914 label is reused, loop optimization will
3915 be disabled for that loop. */
3916 new_label = gen_label_rtx ();
3917 emit_label_after (new_label, PREV_INSN (prev));
3919 changed |= redirect_jump (b1, new_label, 1);
3924 /* If either of these is not a normal insn (it might be
3925 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3926 have already been skipped above.) Similarly, fail
3927 if the insns are different. */
3928 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
3929 || recog_memoized (t1) != recog_memoized (t2)
3930 || ! rtx_equal_for_thread_p (PATTERN (t1),
3934 t1 = prev_nonnote_insn (t1);
3935 t2 = prev_nonnote_insn (t2);
3942 free (modified_regs);
3947 /* This is like RTX_EQUAL_P except that it knows about our handling of
3948 possibly equivalent registers and knows to consider volatile and
3949 modified objects as not equal.
3951 YINSN is the insn containing Y. */
3954 rtx_equal_for_thread_p (x, y, yinsn)
3960 register enum rtx_code code;
3961 register const char *fmt;
3963 code = GET_CODE (x);
3964 /* Rtx's of different codes cannot be equal. */
3965 if (code != GET_CODE (y))
3968 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
3969 (REG:SI x) and (REG:HI x) are NOT equivalent. */
3971 if (GET_MODE (x) != GET_MODE (y))
3974 /* For floating-point, consider everything unequal. This is a bit
3975 pessimistic, but this pass would only rarely do anything for FP
3977 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3978 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
3981 /* For commutative operations, the RTX match if the operand match in any
3982 order. Also handle the simple binary and unary cases without a loop. */
3983 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3984 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
3985 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
3986 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
3987 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
3988 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3989 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
3990 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
3991 else if (GET_RTX_CLASS (code) == '1')
3992 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
3994 /* Handle special-cases first. */
3998 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4001 /* If neither is user variable or hard register, check for possible
4003 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4004 || REGNO (x) < FIRST_PSEUDO_REGISTER
4005 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4008 if (same_regs[REGNO (x)] == -1)
4010 same_regs[REGNO (x)] = REGNO (y);
4013 /* If this is the first time we are seeing a register on the `Y'
4014 side, see if it is the last use. If not, we can't thread the
4015 jump, so mark it as not equivalent. */
4016 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4022 return (same_regs[REGNO (x)] == (int) REGNO (y));
4027 /* If memory modified or either volatile, not equivalent.
4028 Else, check address. */
4029 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4032 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4035 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4041 /* Cancel a pending `same_regs' if setting equivalenced registers.
4042 Then process source. */
4043 if (GET_CODE (SET_DEST (x)) == REG
4044 && GET_CODE (SET_DEST (y)) == REG)
4046 if (same_regs[REGNO (SET_DEST (x))] == (int) REGNO (SET_DEST (y)))
4048 same_regs[REGNO (SET_DEST (x))] = -1;
4051 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4055 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4058 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4061 return XEXP (x, 0) == XEXP (y, 0);
4064 return XSTR (x, 0) == XSTR (y, 0);
4073 fmt = GET_RTX_FORMAT (code);
4074 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4079 if (XWINT (x, i) != XWINT (y, i))
4085 if (XINT (x, i) != XINT (y, i))
4091 /* Two vectors must have the same length. */
4092 if (XVECLEN (x, i) != XVECLEN (y, i))
4095 /* And the corresponding elements must match. */
4096 for (j = 0; j < XVECLEN (x, i); j++)
4097 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4098 XVECEXP (y, i, j), yinsn) == 0)
4103 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4109 if (strcmp (XSTR (x, i), XSTR (y, i)))
4114 /* These are just backpointers, so they don't matter. */
4121 /* It is believed that rtx's at this level will never
4122 contain anything but integers and other rtx's,
4123 except for within LABEL_REFs and SYMBOL_REFs. */