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 int redirect_exp PARAMS ((rtx, rtx, rtx));
126 static void invert_exp_1 PARAMS ((rtx));
127 static int invert_exp PARAMS ((rtx));
128 static void delete_from_jump_chain PARAMS ((rtx));
129 static int delete_labelref_insn PARAMS ((rtx, rtx, int));
130 static void mark_modified_reg PARAMS ((rtx, rtx, void *));
131 static void redirect_tablejump PARAMS ((rtx, rtx));
132 static void jump_optimize_1 PARAMS ((rtx, int, int, int, int, int));
133 static int returnjump_p_1 PARAMS ((rtx *, void *));
134 static void delete_prior_computation PARAMS ((rtx, rtx));
136 /* Main external entry point into the jump optimizer. See comments before
137 jump_optimize_1 for descriptions of the arguments. */
139 jump_optimize (f, cross_jump, noop_moves, after_regscan)
145 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0, 0);
148 /* Alternate entry into the jump optimizer. This entry point only rebuilds
149 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
152 rebuild_jump_labels (f)
155 jump_optimize_1 (f, 0, 0, 0, 1, 0);
158 /* Alternate entry into the jump optimizer. Do only trivial optimizations. */
160 jump_optimize_minimal (f)
163 jump_optimize_1 (f, 0, 0, 0, 0, 1);
166 /* Delete no-op jumps and optimize jumps to jumps
167 and jumps around jumps.
168 Delete unused labels and unreachable code.
170 If CROSS_JUMP is 1, detect matching code
171 before a jump and its destination and unify them.
172 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
174 If NOOP_MOVES is nonzero, delete no-op move insns.
176 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
177 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
179 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
180 and JUMP_LABEL field for jumping insns.
182 If `optimize' is zero, don't change any code,
183 just determine whether control drops off the end of the function.
184 This case occurs when we have -W and not -O.
185 It works because `delete_insn' checks the value of `optimize'
186 and refrains from actually deleting when that is 0.
188 If MINIMAL is nonzero, then we only perform trivial optimizations:
190 * Removal of unreachable code after BARRIERs.
191 * Removal of unreferenced CODE_LABELs.
192 * Removal of a jump to the next instruction.
193 * Removal of a conditional jump followed by an unconditional jump
194 to the same target as the conditional jump.
195 * Simplify a conditional jump around an unconditional jump.
196 * Simplify a jump to a jump.
197 * Delete extraneous line number notes.
201 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan,
202 mark_labels_only, minimal)
207 int mark_labels_only;
210 register rtx insn, next;
217 cross_jump_death_matters = (cross_jump == 2);
218 max_uid = init_label_info (f) + 1;
220 /* If we are performing cross jump optimizations, then initialize
221 tables mapping UIDs to EH regions to avoid incorrect movement
222 of insns from one EH region to another. */
223 if (flag_exceptions && cross_jump)
224 init_insn_eh_region (f, max_uid);
226 if (! mark_labels_only)
227 delete_barrier_successors (f);
229 /* Leave some extra room for labels and duplicate exit test insns
231 max_jump_chain = max_uid * 14 / 10;
232 jump_chain = (rtx *) xcalloc (max_jump_chain, sizeof (rtx));
234 mark_all_labels (f, cross_jump);
236 /* Keep track of labels used from static data; we don't track them
237 closely enough to delete them here, so make sure their reference
238 count doesn't drop to zero. */
240 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
241 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
242 LABEL_NUSES (XEXP (insn, 0))++;
244 check_exception_handler_labels ();
246 /* Keep track of labels used for marking handlers for exception
247 regions; they cannot usually be deleted. */
249 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
250 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
251 LABEL_NUSES (XEXP (insn, 0))++;
253 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
254 notes and recompute LABEL_NUSES. */
255 if (mark_labels_only)
259 exception_optimize ();
261 last_insn = delete_unreferenced_labels (f);
264 delete_noop_moves (f);
266 /* If we haven't yet gotten to reload and we have just run regscan,
267 delete any insn that sets a register that isn't used elsewhere.
268 This helps some of the optimizations below by having less insns
269 being jumped around. */
271 if (optimize && ! reload_completed && after_regscan)
272 for (insn = f; insn; insn = next)
274 rtx set = single_set (insn);
276 next = NEXT_INSN (insn);
278 if (set && GET_CODE (SET_DEST (set)) == REG
279 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
280 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
281 /* We use regno_last_note_uid so as not to delete the setting
282 of a reg that's used in notes. A subsequent optimization
283 might arrange to use that reg for real. */
284 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
285 && ! side_effects_p (SET_SRC (set))
286 && ! find_reg_note (insn, REG_RETVAL, 0)
287 /* An ADDRESSOF expression can turn into a use of the internal arg
288 pointer, so do not delete the initialization of the internal
289 arg pointer yet. If it is truly dead, flow will delete the
290 initializing insn. */
291 && SET_DEST (set) != current_function_internal_arg_pointer)
295 /* Now iterate optimizing jumps until nothing changes over one pass. */
297 old_max_reg = max_reg_num ();
302 for (insn = f; insn; insn = next)
305 rtx temp, temp1, temp2 = NULL_RTX;
306 rtx temp4 ATTRIBUTE_UNUSED;
308 int this_is_any_uncondjump;
309 int this_is_any_condjump;
310 int this_is_onlyjump;
312 next = NEXT_INSN (insn);
314 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
315 jump. Try to optimize by duplicating the loop exit test if so.
316 This is only safe immediately after regscan, because it uses
317 the values of regno_first_uid and regno_last_uid. */
318 if (after_regscan && GET_CODE (insn) == NOTE
319 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
320 && (temp1 = next_nonnote_insn (insn)) != 0
321 && any_uncondjump_p (temp1)
322 && onlyjump_p (temp1))
324 temp = PREV_INSN (insn);
325 if (duplicate_loop_exit_test (insn))
328 next = NEXT_INSN (temp);
333 if (GET_CODE (insn) != JUMP_INSN)
336 this_is_any_condjump = any_condjump_p (insn);
337 this_is_any_uncondjump = any_uncondjump_p (insn);
338 this_is_onlyjump = onlyjump_p (insn);
340 /* Tension the labels in dispatch tables. */
342 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
343 changed |= tension_vector_labels (PATTERN (insn), 0);
344 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
345 changed |= tension_vector_labels (PATTERN (insn), 1);
347 /* See if this jump goes to another jump and redirect if so. */
348 nlabel = follow_jumps (JUMP_LABEL (insn));
349 if (nlabel != JUMP_LABEL (insn))
350 changed |= redirect_jump (insn, nlabel, 1);
352 if (! optimize || minimal)
355 /* If a dispatch table always goes to the same place,
356 get rid of it and replace the insn that uses it. */
358 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
359 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
362 rtx pat = PATTERN (insn);
363 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
364 int len = XVECLEN (pat, diff_vec_p);
365 rtx dispatch = prev_real_insn (insn);
368 for (i = 0; i < len; i++)
369 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
370 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
375 && GET_CODE (dispatch) == JUMP_INSN
376 && JUMP_LABEL (dispatch) != 0
377 /* Don't mess with a casesi insn.
378 XXX according to the comment before computed_jump_p(),
379 all casesi insns should be a parallel of the jump
380 and a USE of a LABEL_REF. */
381 && ! ((set = single_set (dispatch)) != NULL
382 && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE))
383 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
385 redirect_tablejump (dispatch,
386 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
391 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
393 /* Detect jump to following insn. */
394 if (reallabelprev == insn
395 && (this_is_any_condjump || this_is_any_uncondjump)
398 next = next_real_insn (JUMP_LABEL (insn));
401 /* Remove the "inactive" but "real" insns (i.e. uses and
402 clobbers) in between here and there. */
404 while ((temp = next_real_insn (temp)) != next)
411 /* Detect a conditional jump going to the same place
412 as an immediately following unconditional jump. */
413 else if (this_is_any_condjump && this_is_onlyjump
414 && (temp = next_active_insn (insn)) != 0
415 && simplejump_p (temp)
416 && (next_active_insn (JUMP_LABEL (insn))
417 == next_active_insn (JUMP_LABEL (temp))))
419 /* Don't mess up test coverage analysis. */
421 if (flag_test_coverage && !reload_completed)
422 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
423 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
434 /* Detect a conditional jump jumping over an unconditional jump. */
436 else if (this_is_any_condjump
437 && reallabelprev != 0
438 && GET_CODE (reallabelprev) == JUMP_INSN
439 && prev_active_insn (reallabelprev) == insn
440 && no_labels_between_p (insn, reallabelprev)
441 && any_uncondjump_p (reallabelprev)
442 && onlyjump_p (reallabelprev))
444 /* When we invert the unconditional jump, we will be
445 decrementing the usage count of its old label.
446 Make sure that we don't delete it now because that
447 might cause the following code to be deleted. */
448 rtx prev_uses = prev_nonnote_insn (reallabelprev);
449 rtx prev_label = JUMP_LABEL (insn);
452 ++LABEL_NUSES (prev_label);
454 if (invert_jump (insn, JUMP_LABEL (reallabelprev), 1))
456 /* It is very likely that if there are USE insns before
457 this jump, they hold REG_DEAD notes. These REG_DEAD
458 notes are no longer valid due to this optimization,
459 and will cause the life-analysis that following passes
460 (notably delayed-branch scheduling) to think that
461 these registers are dead when they are not.
463 To prevent this trouble, we just remove the USE insns
464 from the insn chain. */
466 while (prev_uses && GET_CODE (prev_uses) == INSN
467 && GET_CODE (PATTERN (prev_uses)) == USE)
469 rtx useless = prev_uses;
470 prev_uses = prev_nonnote_insn (prev_uses);
471 delete_insn (useless);
474 delete_insn (reallabelprev);
478 /* We can now safely delete the label if it is unreferenced
479 since the delete_insn above has deleted the BARRIER. */
480 if (prev_label && --LABEL_NUSES (prev_label) == 0)
481 delete_insn (prev_label);
483 next = NEXT_INSN (insn);
486 /* If we have an unconditional jump preceded by a USE, try to put
487 the USE before the target and jump there. This simplifies many
488 of the optimizations below since we don't have to worry about
489 dealing with these USE insns. We only do this if the label
490 being branch to already has the identical USE or if code
491 never falls through to that label. */
493 else if (this_is_any_uncondjump
494 && (temp = prev_nonnote_insn (insn)) != 0
495 && GET_CODE (temp) == INSN
496 && GET_CODE (PATTERN (temp)) == USE
497 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
498 && (GET_CODE (temp1) == BARRIER
499 || (GET_CODE (temp1) == INSN
500 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
501 /* Don't do this optimization if we have a loop containing
502 only the USE instruction, and the loop start label has
503 a usage count of 1. This is because we will redo this
504 optimization everytime through the outer loop, and jump
505 opt will never exit. */
506 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
507 && temp2 == JUMP_LABEL (insn)
508 && LABEL_NUSES (temp2) == 1))
510 if (GET_CODE (temp1) == BARRIER)
512 emit_insn_after (PATTERN (temp), temp1);
513 temp1 = NEXT_INSN (temp1);
517 redirect_jump (insn, get_label_before (temp1), 1);
518 reallabelprev = prev_real_insn (temp1);
520 next = NEXT_INSN (insn);
524 /* Detect a conditional jump jumping over an unconditional trap. */
526 && this_is_any_condjump && this_is_onlyjump
527 && reallabelprev != 0
528 && GET_CODE (reallabelprev) == INSN
529 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
530 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
531 && prev_active_insn (reallabelprev) == insn
532 && no_labels_between_p (insn, reallabelprev)
533 && (temp2 = get_condition (insn, &temp4))
534 && can_reverse_comparison_p (temp2, insn))
536 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
537 XEXP (temp2, 0), XEXP (temp2, 1),
538 TRAP_CODE (PATTERN (reallabelprev)));
542 emit_insn_before (new, temp4);
543 delete_insn (reallabelprev);
549 /* Detect a jump jumping to an unconditional trap. */
550 else if (HAVE_trap && this_is_onlyjump
551 && (temp = next_active_insn (JUMP_LABEL (insn)))
552 && GET_CODE (temp) == INSN
553 && GET_CODE (PATTERN (temp)) == TRAP_IF
554 && (this_is_any_uncondjump
555 || (this_is_any_condjump
556 && (temp2 = get_condition (insn, &temp4)))))
558 rtx tc = TRAP_CONDITION (PATTERN (temp));
560 if (tc == const_true_rtx
561 || (! this_is_any_uncondjump && rtx_equal_p (temp2, tc)))
564 /* Replace an unconditional jump to a trap with a trap. */
565 if (this_is_any_uncondjump)
567 emit_barrier_after (emit_insn_before (gen_trap (), insn));
572 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
574 TRAP_CODE (PATTERN (temp)));
577 emit_insn_before (new, temp4);
583 /* If the trap condition and jump condition are mutually
584 exclusive, redirect the jump to the following insn. */
585 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
586 && this_is_any_condjump
587 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
588 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
589 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
590 && redirect_jump (insn, get_label_after (temp), 1))
599 /* Now that the jump has been tensioned,
600 try cross jumping: check for identical code
601 before the jump and before its target label. */
603 /* First, cross jumping of conditional jumps: */
605 if (cross_jump && condjump_p (insn))
607 rtx newjpos, newlpos;
608 rtx x = prev_real_insn (JUMP_LABEL (insn));
610 /* A conditional jump may be crossjumped
611 only if the place it jumps to follows
612 an opposing jump that comes back here. */
614 if (x != 0 && ! jump_back_p (x, insn))
615 /* We have no opposing jump;
616 cannot cross jump this insn. */
620 /* TARGET is nonzero if it is ok to cross jump
621 to code before TARGET. If so, see if matches. */
623 find_cross_jump (insn, x, 2,
628 do_cross_jump (insn, newjpos, newlpos);
629 /* Make the old conditional jump
630 into an unconditional one. */
631 SET_SRC (PATTERN (insn))
632 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
633 INSN_CODE (insn) = -1;
634 emit_barrier_after (insn);
635 /* Add to jump_chain unless this is a new label
636 whose UID is too large. */
637 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
639 jump_chain[INSN_UID (insn)]
640 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
641 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
648 /* Cross jumping of unconditional jumps:
649 a few differences. */
651 if (cross_jump && simplejump_p (insn))
653 rtx newjpos, newlpos;
658 /* TARGET is nonzero if it is ok to cross jump
659 to code before TARGET. If so, see if matches. */
660 find_cross_jump (insn, JUMP_LABEL (insn), 1,
663 /* If cannot cross jump to code before the label,
664 see if we can cross jump to another jump to
666 /* Try each other jump to this label. */
667 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
668 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
669 target != 0 && newjpos == 0;
670 target = jump_chain[INSN_UID (target)])
672 && JUMP_LABEL (target) == JUMP_LABEL (insn)
673 /* Ignore TARGET if it's deleted. */
674 && ! INSN_DELETED_P (target))
675 find_cross_jump (insn, target, 2,
680 do_cross_jump (insn, newjpos, newlpos);
686 /* This code was dead in the previous jump.c! */
687 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
689 /* Return insns all "jump to the same place"
690 so we can cross-jump between any two of them. */
692 rtx newjpos, newlpos, target;
696 /* If cannot cross jump to code before the label,
697 see if we can cross jump to another jump to
699 /* Try each other jump to this label. */
700 for (target = jump_chain[0];
701 target != 0 && newjpos == 0;
702 target = jump_chain[INSN_UID (target)])
704 && ! INSN_DELETED_P (target)
705 && GET_CODE (PATTERN (target)) == RETURN)
706 find_cross_jump (insn, target, 2,
711 do_cross_jump (insn, newjpos, newlpos);
722 /* Delete extraneous line number notes.
723 Note that two consecutive notes for different lines are not really
724 extraneous. There should be some indication where that line belonged,
725 even if it became empty. */
730 for (insn = f; insn; insn = NEXT_INSN (insn))
731 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
733 /* Delete this note if it is identical to previous note. */
735 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
736 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
746 /* CAN_REACH_END is persistent for each function. Once set it should
747 not be cleared. This is especially true for the case where we
748 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
749 the front-end before compiling each function. */
750 if (! minimal && calculate_can_reach_end (last_insn, optimize != 0))
759 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
760 notes whose labels don't occur in the insn any more. Returns the
761 largest INSN_UID found. */
769 for (insn = f; insn; insn = NEXT_INSN (insn))
771 if (GET_CODE (insn) == CODE_LABEL)
772 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
773 else if (GET_CODE (insn) == JUMP_INSN)
774 JUMP_LABEL (insn) = 0;
775 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
779 for (note = REG_NOTES (insn); note; note = next)
781 next = XEXP (note, 1);
782 if (REG_NOTE_KIND (note) == REG_LABEL
783 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
784 remove_note (insn, note);
787 if (INSN_UID (insn) > largest_uid)
788 largest_uid = INSN_UID (insn);
794 /* Delete insns following barriers, up to next label.
796 Also delete no-op jumps created by gcse. */
799 delete_barrier_successors (f)
805 for (insn = f; insn;)
807 if (GET_CODE (insn) == BARRIER)
809 insn = NEXT_INSN (insn);
811 never_reached_warning (insn);
813 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
815 if (GET_CODE (insn) == NOTE
816 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
817 insn = NEXT_INSN (insn);
819 insn = delete_insn (insn);
821 /* INSN is now the code_label. */
824 /* Also remove (set (pc) (pc)) insns which can be created by
825 gcse. We eliminate such insns now to avoid having them
826 cause problems later. */
827 else if (GET_CODE (insn) == JUMP_INSN
828 && (set = pc_set (insn)) != NULL
829 && SET_SRC (set) == pc_rtx
830 && SET_DEST (set) == pc_rtx
831 && onlyjump_p (insn))
832 insn = delete_insn (insn);
835 insn = NEXT_INSN (insn);
839 /* Mark the label each jump jumps to.
840 Combine consecutive labels, and count uses of labels.
842 For each label, make a chain (using `jump_chain')
843 of all the *unconditional* jumps that jump to it;
844 also make a chain of all returns.
846 CROSS_JUMP indicates whether we are doing cross jumping
847 and if we are whether we will be paying attention to
848 death notes or not. */
851 mark_all_labels (f, cross_jump)
857 for (insn = f; insn; insn = NEXT_INSN (insn))
858 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
860 if (GET_CODE (insn) == CALL_INSN
861 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
863 mark_all_labels (XEXP (PATTERN (insn), 0), cross_jump);
864 mark_all_labels (XEXP (PATTERN (insn), 1), cross_jump);
865 mark_all_labels (XEXP (PATTERN (insn), 2), cross_jump);
869 mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
870 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
872 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
874 jump_chain[INSN_UID (insn)]
875 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
876 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
878 if (GET_CODE (PATTERN (insn)) == RETURN)
880 jump_chain[INSN_UID (insn)] = jump_chain[0];
881 jump_chain[0] = insn;
887 /* Delete all labels already not referenced.
888 Also find and return the last insn. */
891 delete_unreferenced_labels (f)
894 rtx final = NULL_RTX;
897 for (insn = f; insn; )
899 if (GET_CODE (insn) == CODE_LABEL
900 && LABEL_NUSES (insn) == 0
901 && LABEL_ALTERNATE_NAME (insn) == NULL)
902 insn = delete_insn (insn);
906 insn = NEXT_INSN (insn);
913 /* Delete various simple forms of moves which have no necessary
917 delete_noop_moves (f)
922 for (insn = f; insn; )
924 next = NEXT_INSN (insn);
926 if (GET_CODE (insn) == INSN)
928 register rtx body = PATTERN (insn);
930 /* Detect and delete no-op move instructions
931 resulting from not allocating a parameter in a register. */
933 if (GET_CODE (body) == SET
934 && (SET_DEST (body) == SET_SRC (body)
935 || (GET_CODE (SET_DEST (body)) == MEM
936 && GET_CODE (SET_SRC (body)) == MEM
937 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
938 && ! (GET_CODE (SET_DEST (body)) == MEM
939 && MEM_VOLATILE_P (SET_DEST (body)))
940 && ! (GET_CODE (SET_SRC (body)) == MEM
941 && MEM_VOLATILE_P (SET_SRC (body))))
942 delete_computation (insn);
944 /* Detect and ignore no-op move instructions
945 resulting from smart or fortuitous register allocation. */
947 else if (GET_CODE (body) == SET)
949 int sreg = true_regnum (SET_SRC (body));
950 int dreg = true_regnum (SET_DEST (body));
952 if (sreg == dreg && sreg >= 0)
954 else if (sreg >= 0 && dreg >= 0)
957 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
958 sreg, NULL_PTR, dreg,
959 GET_MODE (SET_SRC (body)));
962 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
964 /* DREG may have been the target of a REG_DEAD note in
965 the insn which makes INSN redundant. If so, reorg
966 would still think it is dead. So search for such a
967 note and delete it if we find it. */
968 if (! find_regno_note (insn, REG_UNUSED, dreg))
969 for (trial = prev_nonnote_insn (insn);
970 trial && GET_CODE (trial) != CODE_LABEL;
971 trial = prev_nonnote_insn (trial))
972 if (find_regno_note (trial, REG_DEAD, dreg))
974 remove_death (dreg, trial);
978 /* Deleting insn could lose a death-note for SREG. */
979 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
981 /* Change this into a USE so that we won't emit
982 code for it, but still can keep the note. */
984 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
985 INSN_CODE (insn) = -1;
986 /* Remove all reg notes but the REG_DEAD one. */
987 REG_NOTES (insn) = trial;
988 XEXP (trial, 1) = NULL_RTX;
994 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
995 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
997 GET_MODE (SET_DEST (body))))
999 /* This handles the case where we have two consecutive
1000 assignments of the same constant to pseudos that didn't
1001 get a hard reg. Each SET from the constant will be
1002 converted into a SET of the spill register and an
1003 output reload will be made following it. This produces
1004 two loads of the same constant into the same spill
1009 /* Look back for a death note for the first reg.
1010 If there is one, it is no longer accurate. */
1011 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
1013 if ((GET_CODE (in_insn) == INSN
1014 || GET_CODE (in_insn) == JUMP_INSN)
1015 && find_regno_note (in_insn, REG_DEAD, dreg))
1017 remove_death (dreg, in_insn);
1020 in_insn = PREV_INSN (in_insn);
1023 /* Delete the second load of the value. */
1027 else if (GET_CODE (body) == PARALLEL)
1029 /* If each part is a set between two identical registers or
1030 a USE or CLOBBER, delete the insn. */
1034 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
1036 tem = XVECEXP (body, 0, i);
1037 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
1040 if (GET_CODE (tem) != SET
1041 || (sreg = true_regnum (SET_SRC (tem))) < 0
1042 || (dreg = true_regnum (SET_DEST (tem))) < 0
1050 /* Also delete insns to store bit fields if they are no-ops. */
1051 /* Not worth the hair to detect this in the big-endian case. */
1052 else if (! BYTES_BIG_ENDIAN
1053 && GET_CODE (body) == SET
1054 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
1055 && XEXP (SET_DEST (body), 2) == const0_rtx
1056 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
1057 && ! (GET_CODE (SET_SRC (body)) == MEM
1058 && MEM_VOLATILE_P (SET_SRC (body))))
1065 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1066 If so indicate that this function can drop off the end by returning
1069 CHECK_DELETED indicates whether we must check if the note being
1070 searched for has the deleted flag set.
1072 DELETE_FINAL_NOTE indicates whether we should delete the note
1076 calculate_can_reach_end (last, delete_final_note)
1078 int delete_final_note;
1083 while (insn != NULL_RTX)
1087 /* One label can follow the end-note: the return label. */
1088 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
1090 /* Ordinary insns can follow it if returning a structure. */
1091 else if (GET_CODE (insn) == INSN)
1093 /* If machine uses explicit RETURN insns, no epilogue,
1094 then one of them follows the note. */
1095 else if (GET_CODE (insn) == JUMP_INSN
1096 && GET_CODE (PATTERN (insn)) == RETURN)
1098 /* A barrier can follow the return insn. */
1099 else if (GET_CODE (insn) == BARRIER)
1101 /* Other kinds of notes can follow also. */
1102 else if (GET_CODE (insn) == NOTE
1103 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
1109 insn = PREV_INSN (insn);
1112 /* See if we backed up to the appropriate type of note. */
1113 if (insn != NULL_RTX
1114 && GET_CODE (insn) == NOTE
1115 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
1117 if (delete_final_note)
1125 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1126 jump. Assume that this unconditional jump is to the exit test code. If
1127 the code is sufficiently simple, make a copy of it before INSN,
1128 followed by a jump to the exit of the loop. Then delete the unconditional
1131 Return 1 if we made the change, else 0.
1133 This is only safe immediately after a regscan pass because it uses the
1134 values of regno_first_uid and regno_last_uid. */
1137 duplicate_loop_exit_test (loop_start)
1140 rtx insn, set, reg, p, link;
1141 rtx copy = 0, first_copy = 0;
1143 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
1145 int max_reg = max_reg_num ();
1148 /* Scan the exit code. We do not perform this optimization if any insn:
1152 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1153 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1154 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1157 We also do not do this if we find an insn with ASM_OPERANDS. While
1158 this restriction should not be necessary, copying an insn with
1159 ASM_OPERANDS can confuse asm_noperands in some cases.
1161 Also, don't do this if the exit code is more than 20 insns. */
1163 for (insn = exitcode;
1165 && ! (GET_CODE (insn) == NOTE
1166 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
1167 insn = NEXT_INSN (insn))
1169 switch (GET_CODE (insn))
1175 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
1176 a jump immediately after the loop start that branches outside
1177 the loop but within an outer loop, near the exit test.
1178 If we copied this exit test and created a phony
1179 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
1180 before the exit test look like these could be safely moved
1181 out of the loop even if they actually may be never executed.
1182 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
1184 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1185 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
1189 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1190 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
1191 /* If we were to duplicate this code, we would not move
1192 the BLOCK notes, and so debugging the moved code would
1193 be difficult. Thus, we only move the code with -O2 or
1200 /* The code below would grossly mishandle REG_WAS_0 notes,
1201 so get rid of them here. */
1202 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
1203 remove_note (insn, p);
1204 if (++num_insns > 20
1205 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1206 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
1214 /* Unless INSN is zero, we can do the optimization. */
1220 /* See if any insn sets a register only used in the loop exit code and
1221 not a user variable. If so, replace it with a new register. */
1222 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1223 if (GET_CODE (insn) == INSN
1224 && (set = single_set (insn)) != 0
1225 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
1226 || (GET_CODE (reg) == SUBREG
1227 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
1228 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
1229 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
1231 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
1232 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
1237 /* We can do the replacement. Allocate reg_map if this is the
1238 first replacement we found. */
1240 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
1242 REG_LOOP_TEST_P (reg) = 1;
1244 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
1248 /* Now copy each insn. */
1249 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1251 switch (GET_CODE (insn))
1254 copy = emit_barrier_before (loop_start);
1257 /* Only copy line-number notes. */
1258 if (NOTE_LINE_NUMBER (insn) >= 0)
1260 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
1261 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
1266 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
1268 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1270 mark_jump_label (PATTERN (copy), copy, 0, 0);
1272 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1274 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1275 if (REG_NOTE_KIND (link) != REG_LABEL)
1277 if (GET_CODE (link) == EXPR_LIST)
1279 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
1284 = copy_insn_1 (gen_rtx_INSN_LIST (REG_NOTE_KIND (link),
1289 if (reg_map && REG_NOTES (copy))
1290 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1294 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)), loop_start);
1296 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1297 mark_jump_label (PATTERN (copy), copy, 0, 0);
1298 if (REG_NOTES (insn))
1300 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
1302 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1305 /* If this is a simple jump, add it to the jump chain. */
1307 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
1308 && simplejump_p (copy))
1310 jump_chain[INSN_UID (copy)]
1311 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1312 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1320 /* Record the first insn we copied. We need it so that we can
1321 scan the copied insns for new pseudo registers. */
1326 /* Now clean up by emitting a jump to the end label and deleting the jump
1327 at the start of the loop. */
1328 if (! copy || GET_CODE (copy) != BARRIER)
1330 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
1333 /* Record the first insn we copied. We need it so that we can
1334 scan the copied insns for new pseudo registers. This may not
1335 be strictly necessary since we should have copied at least one
1336 insn above. But I am going to be safe. */
1340 mark_jump_label (PATTERN (copy), copy, 0, 0);
1341 if (INSN_UID (copy) < max_jump_chain
1342 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
1344 jump_chain[INSN_UID (copy)]
1345 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1346 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1348 emit_barrier_before (loop_start);
1351 /* Now scan from the first insn we copied to the last insn we copied
1352 (copy) for new pseudo registers. Do this after the code to jump to
1353 the end label since that might create a new pseudo too. */
1354 reg_scan_update (first_copy, copy, max_reg);
1356 /* Mark the exit code as the virtual top of the converted loop. */
1357 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
1359 delete_insn (next_nonnote_insn (loop_start));
1368 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
1369 eh-beg, eh-end notes between START and END out before START. Assume that
1370 END is not such a note. START may be such a note. Returns the value
1371 of the new starting insn, which may be different if the original start
1375 squeeze_notes (start, end)
1381 for (insn = start; insn != end; insn = next)
1383 next = NEXT_INSN (insn);
1384 if (GET_CODE (insn) == NOTE
1385 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
1386 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1387 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1388 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
1389 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
1390 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP
1391 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1392 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1398 rtx prev = PREV_INSN (insn);
1399 PREV_INSN (insn) = PREV_INSN (start);
1400 NEXT_INSN (insn) = start;
1401 NEXT_INSN (PREV_INSN (insn)) = insn;
1402 PREV_INSN (NEXT_INSN (insn)) = insn;
1403 NEXT_INSN (prev) = next;
1404 PREV_INSN (next) = prev;
1412 /* Compare the instructions before insn E1 with those before E2
1413 to find an opportunity for cross jumping.
1414 (This means detecting identical sequences of insns followed by
1415 jumps to the same place, or followed by a label and a jump
1416 to that label, and replacing one with a jump to the other.)
1418 Assume E1 is a jump that jumps to label E2
1419 (that is not always true but it might as well be).
1420 Find the longest possible equivalent sequences
1421 and store the first insns of those sequences into *F1 and *F2.
1422 Store zero there if no equivalent preceding instructions are found.
1424 We give up if we find a label in stream 1.
1425 Actually we could transfer that label into stream 2. */
1428 find_cross_jump (e1, e2, minimum, f1, f2)
1433 register rtx i1 = e1, i2 = e2;
1434 register rtx p1, p2;
1437 rtx last1 = 0, last2 = 0;
1438 rtx afterlast1 = 0, afterlast2 = 0;
1445 i1 = prev_nonnote_insn (i1);
1447 i2 = PREV_INSN (i2);
1448 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
1449 i2 = PREV_INSN (i2);
1454 /* Don't allow the range of insns preceding E1 or E2
1455 to include the other (E2 or E1). */
1456 if (i2 == e1 || i1 == e2)
1459 /* If we will get to this code by jumping, those jumps will be
1460 tensioned to go directly to the new label (before I2),
1461 so this cross-jumping won't cost extra. So reduce the minimum. */
1462 if (GET_CODE (i1) == CODE_LABEL)
1468 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
1471 /* Avoid moving insns across EH regions if either of the insns
1474 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
1475 && !in_same_eh_region (i1, i2))
1481 /* If this is a CALL_INSN, compare register usage information.
1482 If we don't check this on stack register machines, the two
1483 CALL_INSNs might be merged leaving reg-stack.c with mismatching
1484 numbers of stack registers in the same basic block.
1485 If we don't check this on machines with delay slots, a delay slot may
1486 be filled that clobbers a parameter expected by the subroutine.
1488 ??? We take the simple route for now and assume that if they're
1489 equal, they were constructed identically. */
1491 if (GET_CODE (i1) == CALL_INSN
1492 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1493 CALL_INSN_FUNCTION_USAGE (i2)))
1497 /* If cross_jump_death_matters is not 0, the insn's mode
1498 indicates whether or not the insn contains any stack-like
1501 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
1503 /* If register stack conversion has already been done, then
1504 death notes must also be compared before it is certain that
1505 the two instruction streams match. */
1508 HARD_REG_SET i1_regset, i2_regset;
1510 CLEAR_HARD_REG_SET (i1_regset);
1511 CLEAR_HARD_REG_SET (i2_regset);
1513 for (note = REG_NOTES (i1); 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 (i1_regset, REGNO (XEXP (note, 0)));
1518 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1519 if (REG_NOTE_KIND (note) == REG_DEAD
1520 && STACK_REG_P (XEXP (note, 0)))
1521 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1523 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
1532 /* Don't allow old-style asm or volatile extended asms to be accepted
1533 for cross jumping purposes. It is conceptually correct to allow
1534 them, since cross-jumping preserves the dynamic instruction order
1535 even though it is changing the static instruction order. However,
1536 if an asm is being used to emit an assembler pseudo-op, such as
1537 the MIPS `.set reorder' pseudo-op, then the static instruction order
1538 matters and it must be preserved. */
1539 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
1540 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
1541 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
1544 if (lose || GET_CODE (p1) != GET_CODE (p2)
1545 || ! rtx_renumbered_equal_p (p1, p2))
1547 /* The following code helps take care of G++ cleanups. */
1551 if (!lose && GET_CODE (p1) == GET_CODE (p2)
1552 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
1553 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
1554 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
1555 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
1556 /* If the equivalences are not to a constant, they may
1557 reference pseudos that no longer exist, so we can't
1559 && CONSTANT_P (XEXP (equiv1, 0))
1560 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1562 rtx s1 = single_set (i1);
1563 rtx s2 = single_set (i2);
1564 if (s1 != 0 && s2 != 0
1565 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
1567 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
1568 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
1569 if (! rtx_renumbered_equal_p (p1, p2))
1571 else if (apply_change_group ())
1576 /* Insns fail to match; cross jumping is limited to the following
1580 /* Don't allow the insn after a compare to be shared by
1581 cross-jumping unless the compare is also shared.
1582 Here, if either of these non-matching insns is a compare,
1583 exclude the following insn from possible cross-jumping. */
1584 if (sets_cc0_p (p1) || sets_cc0_p (p2))
1585 last1 = afterlast1, last2 = afterlast2, ++minimum;
1588 /* If cross-jumping here will feed a jump-around-jump
1589 optimization, this jump won't cost extra, so reduce
1591 if (GET_CODE (i1) == JUMP_INSN
1593 && prev_real_insn (JUMP_LABEL (i1)) == e1)
1599 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
1601 /* Ok, this insn is potentially includable in a cross-jump here. */
1602 afterlast1 = last1, afterlast2 = last2;
1603 last1 = i1, last2 = i2, --minimum;
1607 if (minimum <= 0 && last1 != 0 && last1 != e1)
1608 *f1 = last1, *f2 = last2;
1612 do_cross_jump (insn, newjpos, newlpos)
1613 rtx insn, newjpos, newlpos;
1615 /* Find an existing label at this point
1616 or make a new one if there is none. */
1617 register rtx label = get_label_before (newlpos);
1619 /* Make the same jump insn jump to the new point. */
1620 if (GET_CODE (PATTERN (insn)) == RETURN)
1622 /* Remove from jump chain of returns. */
1623 delete_from_jump_chain (insn);
1624 /* Change the insn. */
1625 PATTERN (insn) = gen_jump (label);
1626 INSN_CODE (insn) = -1;
1627 JUMP_LABEL (insn) = label;
1628 LABEL_NUSES (label)++;
1629 /* Add to new the jump chain. */
1630 if (INSN_UID (label) < max_jump_chain
1631 && INSN_UID (insn) < max_jump_chain)
1633 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
1634 jump_chain[INSN_UID (label)] = insn;
1638 redirect_jump (insn, label, 1);
1640 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
1641 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
1642 the NEWJPOS stream. */
1644 while (newjpos != insn)
1648 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
1649 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
1650 || REG_NOTE_KIND (lnote) == REG_EQUIV)
1651 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
1652 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
1653 remove_note (newlpos, lnote);
1655 delete_insn (newjpos);
1656 newjpos = next_real_insn (newjpos);
1657 newlpos = next_real_insn (newlpos);
1661 /* Return the label before INSN, or put a new label there. */
1664 get_label_before (insn)
1669 /* Find an existing label at this point
1670 or make a new one if there is none. */
1671 label = prev_nonnote_insn (insn);
1673 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1675 rtx prev = PREV_INSN (insn);
1677 label = gen_label_rtx ();
1678 emit_label_after (label, prev);
1679 LABEL_NUSES (label) = 0;
1684 /* Return the label after INSN, or put a new label there. */
1687 get_label_after (insn)
1692 /* Find an existing label at this point
1693 or make a new one if there is none. */
1694 label = next_nonnote_insn (insn);
1696 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1698 label = gen_label_rtx ();
1699 emit_label_after (label, insn);
1700 LABEL_NUSES (label) = 0;
1705 /* Return 1 if INSN is a jump that jumps to right after TARGET
1706 only on the condition that TARGET itself would drop through.
1707 Assumes that TARGET is a conditional jump. */
1710 jump_back_p (insn, target)
1714 enum rtx_code codei, codet;
1717 if (! any_condjump_p (insn)
1718 || any_uncondjump_p (target)
1719 || target != prev_real_insn (JUMP_LABEL (insn)))
1721 set = pc_set (insn);
1722 tset = pc_set (target);
1724 cinsn = XEXP (SET_SRC (set), 0);
1725 ctarget = XEXP (SET_SRC (tset), 0);
1727 codei = GET_CODE (cinsn);
1728 codet = GET_CODE (ctarget);
1730 if (XEXP (SET_SRC (set), 1) == pc_rtx)
1732 if (! can_reverse_comparison_p (cinsn, insn))
1734 codei = reverse_condition (codei);
1737 if (XEXP (SET_SRC (tset), 2) == pc_rtx)
1739 if (! can_reverse_comparison_p (ctarget, target))
1741 codet = reverse_condition (codet);
1744 return (codei == codet
1745 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
1746 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
1749 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
1750 return non-zero if it is safe to reverse this comparison. It is if our
1751 floating-point is not IEEE, if this is an NE or EQ comparison, or if
1752 this is known to be an integer comparison. */
1755 can_reverse_comparison_p (comparison, insn)
1761 /* If this is not actually a comparison, we can't reverse it. */
1762 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
1765 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
1766 /* If this is an NE comparison, it is safe to reverse it to an EQ
1767 comparison and vice versa, even for floating point. If no operands
1768 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
1769 always false and NE is always true, so the reversal is also valid. */
1771 || GET_CODE (comparison) == NE
1772 || GET_CODE (comparison) == EQ)
1775 arg0 = XEXP (comparison, 0);
1777 /* Make sure ARG0 is one of the actual objects being compared. If we
1778 can't do this, we can't be sure the comparison can be reversed.
1780 Handle cc0 and a MODE_CC register. */
1781 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
1789 /* First see if the condition code mode alone if enough to say we can
1790 reverse the condition. If not, then search backwards for a set of
1791 ARG0. We do not need to check for an insn clobbering it since valid
1792 code will contain set a set with no intervening clobber. But
1793 stop when we reach a label. */
1794 #ifdef REVERSIBLE_CC_MODE
1795 if (GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC
1796 && REVERSIBLE_CC_MODE (GET_MODE (arg0)))
1803 for (prev = prev_nonnote_insn (insn);
1804 prev != 0 && GET_CODE (prev) != CODE_LABEL;
1805 prev = prev_nonnote_insn (prev))
1806 if ((set = single_set (prev)) != 0
1807 && rtx_equal_p (SET_DEST (set), arg0))
1809 arg0 = SET_SRC (set);
1811 if (GET_CODE (arg0) == COMPARE)
1812 arg0 = XEXP (arg0, 0);
1817 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
1818 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
1819 return (GET_CODE (arg0) == CONST_INT
1820 || (GET_MODE (arg0) != VOIDmode
1821 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
1822 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
1825 /* Given an rtx-code for a comparison, return the code for the negated
1826 comparison. If no such code exists, return UNKNOWN.
1828 WATCH OUT! reverse_condition is not safe to use on a jump that might
1829 be acting on the results of an IEEE floating point comparison, because
1830 of the special treatment of non-signaling nans in comparisons.
1831 Use can_reverse_comparison_p to be sure. */
1834 reverse_condition (code)
1877 /* Similar, but we're allowed to generate unordered comparisons, which
1878 makes it safe for IEEE floating-point. Of course, we have to recognize
1879 that the target will support them too... */
1882 reverse_condition_maybe_unordered (code)
1885 /* Non-IEEE formats don't have unordered conditions. */
1886 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
1887 return reverse_condition (code);
1933 /* Similar, but return the code when two operands of a comparison are swapped.
1934 This IS safe for IEEE floating-point. */
1937 swap_condition (code)
1980 /* Given a comparison CODE, return the corresponding unsigned comparison.
1981 If CODE is an equality comparison or already an unsigned comparison,
1982 CODE is returned. */
1985 unsigned_condition (code)
2012 /* Similarly, return the signed version of a comparison. */
2015 signed_condition (code)
2042 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2043 truth of CODE1 implies the truth of CODE2. */
2046 comparison_dominates_p (code1, code2)
2047 enum rtx_code code1, code2;
2055 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
2056 || code2 == ORDERED)
2061 if (code2 == LE || code2 == NE || code2 == ORDERED)
2066 if (code2 == GE || code2 == NE || code2 == ORDERED)
2072 if (code2 == ORDERED)
2077 if (code2 == NE || code2 == ORDERED)
2082 if (code2 == LEU || code2 == NE)
2087 if (code2 == GEU || code2 == NE)
2103 /* Return 1 if INSN is an unconditional jump and nothing else. */
2109 return (GET_CODE (insn) == JUMP_INSN
2110 && GET_CODE (PATTERN (insn)) == SET
2111 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2112 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2115 /* Return nonzero if INSN is a (possibly) conditional jump
2118 Use this function is deprecated, since we need to support combined
2119 branch and compare insns. Use any_condjump_p instead whenever possible. */
2125 register rtx x = PATTERN (insn);
2127 if (GET_CODE (x) != SET
2128 || GET_CODE (SET_DEST (x)) != PC)
2132 if (GET_CODE (x) == LABEL_REF)
2134 else return (GET_CODE (x) == IF_THEN_ELSE
2135 && ((GET_CODE (XEXP (x, 2)) == PC
2136 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
2137 || GET_CODE (XEXP (x, 1)) == RETURN))
2138 || (GET_CODE (XEXP (x, 1)) == PC
2139 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
2140 || GET_CODE (XEXP (x, 2)) == RETURN))));
2145 /* Return nonzero if INSN is a (possibly) conditional jump inside a
2148 Use this function is deprecated, since we need to support combined
2149 branch and compare insns. Use any_condjump_p instead whenever possible. */
2152 condjump_in_parallel_p (insn)
2155 register rtx x = PATTERN (insn);
2157 if (GET_CODE (x) != PARALLEL)
2160 x = XVECEXP (x, 0, 0);
2162 if (GET_CODE (x) != SET)
2164 if (GET_CODE (SET_DEST (x)) != PC)
2166 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2168 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2170 if (XEXP (SET_SRC (x), 2) == pc_rtx
2171 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2172 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2174 if (XEXP (SET_SRC (x), 1) == pc_rtx
2175 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2176 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2181 /* Return set of PC, otherwise NULL. */
2188 if (GET_CODE (insn) != JUMP_INSN)
2190 pat = PATTERN (insn);
2192 /* The set is allowed to appear either as the insn pattern or
2193 the first set in a PARALLEL. */
2194 if (GET_CODE (pat) == PARALLEL)
2195 pat = XVECEXP (pat, 0, 0);
2196 if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
2202 /* Return true when insn is an unconditional direct jump,
2203 possibly bundled inside a PARALLEL. */
2206 any_uncondjump_p (insn)
2209 rtx x = pc_set (insn);
2212 if (GET_CODE (SET_SRC (x)) != LABEL_REF)
2217 /* Return true when insn is a conditional jump. This function works for
2218 instructions containing PC sets in PARALLELs. The instruction may have
2219 various other effects so before removing the jump you must verify
2220 safe_to_remove_jump_p.
2222 Note that unlike condjump_p it returns false for unconditional jumps. */
2225 any_condjump_p (insn)
2228 rtx x = pc_set (insn);
2233 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2236 a = GET_CODE (XEXP (SET_SRC (x), 1));
2237 b = GET_CODE (XEXP (SET_SRC (x), 2));
2239 return ((b == PC && (a == LABEL_REF || a == RETURN))
2240 || (a == PC && (b == LABEL_REF || b == RETURN)));
2243 /* Return the label of a conditional jump. */
2246 condjump_label (insn)
2249 rtx x = pc_set (insn);
2254 if (GET_CODE (x) == LABEL_REF)
2256 if (GET_CODE (x) != IF_THEN_ELSE)
2258 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
2260 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
2265 /* Return true if INSN is a (possibly conditional) return insn. */
2268 returnjump_p_1 (loc, data)
2270 void *data ATTRIBUTE_UNUSED;
2273 return x && GET_CODE (x) == RETURN;
2280 if (GET_CODE (insn) != JUMP_INSN)
2282 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
2285 /* Return true if INSN is a jump that only transfers control and
2294 if (GET_CODE (insn) != JUMP_INSN)
2297 set = single_set (insn);
2300 if (GET_CODE (SET_DEST (set)) != PC)
2302 if (side_effects_p (SET_SRC (set)))
2310 /* Return 1 if X is an RTX that does nothing but set the condition codes
2311 and CLOBBER or USE registers.
2312 Return -1 if X does explicitly set the condition codes,
2313 but also does other things. */
2317 rtx x ATTRIBUTE_UNUSED;
2319 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2321 if (GET_CODE (x) == PARALLEL)
2325 int other_things = 0;
2326 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2328 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2329 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2331 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2334 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2340 /* Follow any unconditional jump at LABEL;
2341 return the ultimate label reached by any such chain of jumps.
2342 If LABEL is not followed by a jump, return LABEL.
2343 If the chain loops or we can't find end, return LABEL,
2344 since that tells caller to avoid changing the insn.
2346 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2347 a USE or CLOBBER. */
2350 follow_jumps (label)
2355 register rtx value = label;
2360 && (insn = next_active_insn (value)) != 0
2361 && GET_CODE (insn) == JUMP_INSN
2362 && ((JUMP_LABEL (insn) != 0 && any_uncondjump_p (insn)
2363 && onlyjump_p (insn))
2364 || GET_CODE (PATTERN (insn)) == RETURN)
2365 && (next = NEXT_INSN (insn))
2366 && GET_CODE (next) == BARRIER);
2369 /* Don't chain through the insn that jumps into a loop
2370 from outside the loop,
2371 since that would create multiple loop entry jumps
2372 and prevent loop optimization. */
2374 if (!reload_completed)
2375 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2376 if (GET_CODE (tem) == NOTE
2377 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
2378 /* ??? Optional. Disables some optimizations, but makes
2379 gcov output more accurate with -O. */
2380 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
2383 /* If we have found a cycle, make the insn jump to itself. */
2384 if (JUMP_LABEL (insn) == label)
2387 tem = next_active_insn (JUMP_LABEL (insn));
2388 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
2389 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
2392 value = JUMP_LABEL (insn);
2399 /* Assuming that field IDX of X is a vector of label_refs,
2400 replace each of them by the ultimate label reached by it.
2401 Return nonzero if a change is made.
2402 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2405 tension_vector_labels (x, idx)
2411 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2413 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2414 register rtx nlabel = follow_jumps (olabel);
2415 if (nlabel && nlabel != olabel)
2417 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2418 ++LABEL_NUSES (nlabel);
2419 if (--LABEL_NUSES (olabel) == 0)
2420 delete_insn (olabel);
2427 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2428 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2429 in INSN, then store one of them in JUMP_LABEL (INSN).
2430 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2431 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2432 Also, when there are consecutive labels, canonicalize on the last of them.
2434 Note that two labels separated by a loop-beginning note
2435 must be kept distinct if we have not yet done loop-optimization,
2436 because the gap between them is where loop-optimize
2437 will want to move invariant code to. CROSS_JUMP tells us
2438 that loop-optimization is done with.
2440 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2441 two labels distinct if they are separated by only USE or CLOBBER insns. */
2444 mark_jump_label (x, insn, cross_jump, in_mem)
2450 register RTX_CODE code = GET_CODE (x);
2452 register const char *fmt;
2474 /* If this is a constant-pool reference, see if it is a label. */
2475 if (CONSTANT_POOL_ADDRESS_P (x))
2476 mark_jump_label (get_pool_constant (x), insn, cross_jump, in_mem);
2481 rtx label = XEXP (x, 0);
2486 /* Ignore remaining references to unreachable labels that
2487 have been deleted. */
2488 if (GET_CODE (label) == NOTE
2489 && NOTE_LINE_NUMBER (label) == NOTE_INSN_DELETED_LABEL)
2492 if (GET_CODE (label) != CODE_LABEL)
2495 /* Ignore references to labels of containing functions. */
2496 if (LABEL_REF_NONLOCAL_P (x))
2499 /* If there are other labels following this one,
2500 replace it with the last of the consecutive labels. */
2501 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
2503 if (GET_CODE (next) == CODE_LABEL)
2505 else if (cross_jump && GET_CODE (next) == INSN
2506 && (GET_CODE (PATTERN (next)) == USE
2507 || GET_CODE (PATTERN (next)) == CLOBBER))
2509 else if (GET_CODE (next) != NOTE)
2511 else if (! cross_jump
2512 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
2513 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
2514 /* ??? Optional. Disables some optimizations, but
2515 makes gcov output more accurate with -O. */
2516 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
2520 XEXP (x, 0) = label;
2521 if (! insn || ! INSN_DELETED_P (insn))
2522 ++LABEL_NUSES (label);
2526 if (GET_CODE (insn) == JUMP_INSN)
2527 JUMP_LABEL (insn) = label;
2529 /* If we've changed OLABEL and we had a REG_LABEL note
2530 for it, update it as well. */
2531 else if (label != olabel
2532 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
2533 XEXP (note, 0) = label;
2535 /* Otherwise, add a REG_LABEL note for LABEL unless there already
2537 else if (! find_reg_note (insn, REG_LABEL, label))
2539 /* This code used to ignore labels which refered to dispatch
2540 tables to avoid flow.c generating worse code.
2542 However, in the presense of global optimizations like
2543 gcse which call find_basic_blocks without calling
2544 life_analysis, not recording such labels will lead
2545 to compiler aborts because of inconsistencies in the
2546 flow graph. So we go ahead and record the label.
2548 It may also be the case that the optimization argument
2549 is no longer valid because of the more accurate cfg
2550 we build in find_basic_blocks -- it no longer pessimizes
2551 code when it finds a REG_LABEL note. */
2552 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
2559 /* Do walk the labels in a vector, but not the first operand of an
2560 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2563 if (! INSN_DELETED_P (insn))
2565 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
2567 for (i = 0; i < XVECLEN (x, eltnum); i++)
2568 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX,
2569 cross_jump, in_mem);
2577 fmt = GET_RTX_FORMAT (code);
2578 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2581 mark_jump_label (XEXP (x, i), insn, cross_jump, in_mem);
2582 else if (fmt[i] == 'E')
2585 for (j = 0; j < XVECLEN (x, i); j++)
2586 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump, in_mem);
2591 /* If all INSN does is set the pc, delete it,
2592 and delete the insn that set the condition codes for it
2593 if that's what the previous thing was. */
2599 register rtx set = single_set (insn);
2601 if (set && GET_CODE (SET_DEST (set)) == PC)
2602 delete_computation (insn);
2605 /* Verify INSN is a BARRIER and delete it. */
2608 delete_barrier (insn)
2611 if (GET_CODE (insn) != BARRIER)
2617 /* Recursively delete prior insns that compute the value (used only by INSN
2618 which the caller is deleting) stored in the register mentioned by NOTE
2619 which is a REG_DEAD note associated with INSN. */
2622 delete_prior_computation (note, insn)
2627 rtx reg = XEXP (note, 0);
2629 for (our_prev = prev_nonnote_insn (insn);
2630 our_prev && (GET_CODE (our_prev) == INSN
2631 || GET_CODE (our_prev) == CALL_INSN);
2632 our_prev = prev_nonnote_insn (our_prev))
2634 rtx pat = PATTERN (our_prev);
2636 /* If we reach a CALL which is not calling a const function
2637 or the callee pops the arguments, then give up. */
2638 if (GET_CODE (our_prev) == CALL_INSN
2639 && (! CONST_CALL_P (our_prev)
2640 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
2643 /* If we reach a SEQUENCE, it is too complex to try to
2644 do anything with it, so give up. */
2645 if (GET_CODE (pat) == SEQUENCE)
2648 if (GET_CODE (pat) == USE
2649 && GET_CODE (XEXP (pat, 0)) == INSN)
2650 /* reorg creates USEs that look like this. We leave them
2651 alone because reorg needs them for its own purposes. */
2654 if (reg_set_p (reg, pat))
2656 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
2659 if (GET_CODE (pat) == PARALLEL)
2661 /* If we find a SET of something else, we can't
2666 for (i = 0; i < XVECLEN (pat, 0); i++)
2668 rtx part = XVECEXP (pat, 0, i);
2670 if (GET_CODE (part) == SET
2671 && SET_DEST (part) != reg)
2675 if (i == XVECLEN (pat, 0))
2676 delete_computation (our_prev);
2678 else if (GET_CODE (pat) == SET
2679 && GET_CODE (SET_DEST (pat)) == REG)
2681 int dest_regno = REGNO (SET_DEST (pat));
2683 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
2684 ? HARD_REGNO_NREGS (dest_regno,
2685 GET_MODE (SET_DEST (pat))) : 1);
2686 int regno = REGNO (reg);
2687 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
2688 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
2690 if (dest_regno >= regno
2691 && dest_endregno <= endregno)
2692 delete_computation (our_prev);
2694 /* We may have a multi-word hard register and some, but not
2695 all, of the words of the register are needed in subsequent
2696 insns. Write REG_UNUSED notes for those parts that were not
2698 else if (dest_regno <= regno
2699 && dest_endregno >= endregno)
2703 REG_NOTES (our_prev)
2704 = gen_rtx_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (our_prev));
2706 for (i = dest_regno; i < dest_endregno; i++)
2707 if (! find_regno_note (our_prev, REG_UNUSED, i))
2710 if (i == dest_endregno)
2711 delete_computation (our_prev);
2718 /* If PAT references the register that dies here, it is an
2719 additional use. Hence any prior SET isn't dead. However, this
2720 insn becomes the new place for the REG_DEAD note. */
2721 if (reg_overlap_mentioned_p (reg, pat))
2723 XEXP (note, 1) = REG_NOTES (our_prev);
2724 REG_NOTES (our_prev) = note;
2730 /* Delete INSN and recursively delete insns that compute values used only
2731 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2732 If we are running before flow.c, we need do nothing since flow.c will
2733 delete dead code. We also can't know if the registers being used are
2734 dead or not at this point.
2736 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2737 nothing other than set a register that dies in this insn, we can delete
2740 On machines with CC0, if CC0 is used in this insn, we may be able to
2741 delete the insn that set it. */
2744 delete_computation (insn)
2751 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
2753 rtx prev = prev_nonnote_insn (insn);
2754 /* We assume that at this stage
2755 CC's are always set explicitly
2756 and always immediately before the jump that
2757 will use them. So if the previous insn
2758 exists to set the CC's, delete it
2759 (unless it performs auto-increments, etc.). */
2760 if (prev && GET_CODE (prev) == INSN
2761 && sets_cc0_p (PATTERN (prev)))
2763 if (sets_cc0_p (PATTERN (prev)) > 0
2764 && ! side_effects_p (PATTERN (prev)))
2765 delete_computation (prev);
2767 /* Otherwise, show that cc0 won't be used. */
2768 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
2769 cc0_rtx, REG_NOTES (prev));
2774 #ifdef INSN_SCHEDULING
2775 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
2776 reload has completed. The schedulers need to be fixed. Until
2777 they are, we must not rely on the death notes here. */
2778 if (reload_completed && flag_schedule_insns_after_reload)
2785 /* The REG_DEAD note may have been omitted for a register
2786 which is both set and used by the insn. */
2787 set = single_set (insn);
2788 if (set && GET_CODE (SET_DEST (set)) == REG)
2790 int dest_regno = REGNO (SET_DEST (set));
2792 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
2793 ? HARD_REGNO_NREGS (dest_regno,
2794 GET_MODE (SET_DEST (set))) : 1);
2797 for (i = dest_regno; i < dest_endregno; i++)
2799 if (! refers_to_regno_p (i, i + 1, SET_SRC (set), NULL_PTR)
2800 || find_regno_note (insn, REG_DEAD, i))
2803 note = gen_rtx_EXPR_LIST (REG_DEAD, (i < FIRST_PSEUDO_REGISTER
2804 ? gen_rtx_REG (reg_raw_mode[i], i)
2805 : SET_DEST (set)), NULL_RTX);
2806 delete_prior_computation (note, insn);
2810 for (note = REG_NOTES (insn); note; note = next)
2812 next = XEXP (note, 1);
2814 if (REG_NOTE_KIND (note) != REG_DEAD
2815 /* Verify that the REG_NOTE is legitimate. */
2816 || GET_CODE (XEXP (note, 0)) != REG)
2819 delete_prior_computation (note, insn);
2825 /* Delete insn INSN from the chain of insns and update label ref counts.
2826 May delete some following insns as a consequence; may even delete
2827 a label elsewhere and insns that follow it.
2829 Returns the first insn after INSN that was not deleted. */
2835 register rtx next = NEXT_INSN (insn);
2836 register rtx prev = PREV_INSN (insn);
2837 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
2838 register int dont_really_delete = 0;
2840 while (next && INSN_DELETED_P (next))
2841 next = NEXT_INSN (next);
2843 /* This insn is already deleted => return first following nondeleted. */
2844 if (INSN_DELETED_P (insn))
2848 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2850 /* Don't delete user-declared labels. When optimizing, convert them
2851 to special NOTEs instead. When not optimizing, leave them alone. */
2852 if (was_code_label && LABEL_NAME (insn) != 0)
2855 dont_really_delete = 1;
2856 else if (! dont_really_delete)
2858 const char *name = LABEL_NAME (insn);
2859 PUT_CODE (insn, NOTE);
2860 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
2861 NOTE_SOURCE_FILE (insn) = name;
2862 dont_really_delete = 1;
2866 /* Mark this insn as deleted. */
2867 INSN_DELETED_P (insn) = 1;
2869 /* If this is an unconditional jump, delete it from the jump chain. */
2870 if (simplejump_p (insn))
2871 delete_from_jump_chain (insn);
2873 /* If instruction is followed by a barrier,
2874 delete the barrier too. */
2876 if (next != 0 && GET_CODE (next) == BARRIER)
2878 INSN_DELETED_P (next) = 1;
2879 next = NEXT_INSN (next);
2882 /* Patch out INSN (and the barrier if any) */
2884 if (! dont_really_delete)
2888 NEXT_INSN (prev) = next;
2889 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
2890 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
2891 XVECLEN (PATTERN (prev), 0) - 1)) = next;
2896 PREV_INSN (next) = prev;
2897 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
2898 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
2901 if (prev && NEXT_INSN (prev) == 0)
2902 set_last_insn (prev);
2905 /* If deleting a jump, decrement the count of the label,
2906 and delete the label if it is now unused. */
2908 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
2910 rtx lab = JUMP_LABEL (insn), lab_next;
2912 if (--LABEL_NUSES (lab) == 0)
2914 /* This can delete NEXT or PREV,
2915 either directly if NEXT is JUMP_LABEL (INSN),
2916 or indirectly through more levels of jumps. */
2919 /* I feel a little doubtful about this loop,
2920 but I see no clean and sure alternative way
2921 to find the first insn after INSN that is not now deleted.
2922 I hope this works. */
2923 while (next && INSN_DELETED_P (next))
2924 next = NEXT_INSN (next);
2927 else if ((lab_next = next_nonnote_insn (lab)) != NULL
2928 && GET_CODE (lab_next) == JUMP_INSN
2929 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
2930 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
2932 /* If we're deleting the tablejump, delete the dispatch table.
2933 We may not be able to kill the label immediately preceeding
2934 just yet, as it might be referenced in code leading up to
2936 delete_insn (lab_next);
2940 /* Likewise if we're deleting a dispatch table. */
2942 if (GET_CODE (insn) == JUMP_INSN
2943 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2944 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2946 rtx pat = PATTERN (insn);
2947 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2948 int len = XVECLEN (pat, diff_vec_p);
2950 for (i = 0; i < len; i++)
2951 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
2952 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
2953 while (next && INSN_DELETED_P (next))
2954 next = NEXT_INSN (next);
2958 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
2959 prev = PREV_INSN (prev);
2961 /* If INSN was a label and a dispatch table follows it,
2962 delete the dispatch table. The tablejump must have gone already.
2963 It isn't useful to fall through into a table. */
2966 && NEXT_INSN (insn) != 0
2967 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
2968 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
2969 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
2970 next = delete_insn (NEXT_INSN (insn));
2972 /* If INSN was a label, delete insns following it if now unreachable. */
2974 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
2976 register RTX_CODE code;
2978 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
2979 || code == NOTE || code == BARRIER
2980 || (code == CODE_LABEL && INSN_DELETED_P (next))))
2983 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
2984 next = NEXT_INSN (next);
2985 /* Keep going past other deleted labels to delete what follows. */
2986 else if (code == CODE_LABEL && INSN_DELETED_P (next))
2987 next = NEXT_INSN (next);
2989 /* Note: if this deletes a jump, it can cause more
2990 deletion of unreachable code, after a different label.
2991 As long as the value from this recursive call is correct,
2992 this invocation functions correctly. */
2993 next = delete_insn (next);
3000 /* Advance from INSN till reaching something not deleted
3001 then return that. May return INSN itself. */
3004 next_nondeleted_insn (insn)
3007 while (INSN_DELETED_P (insn))
3008 insn = NEXT_INSN (insn);
3012 /* Delete a range of insns from FROM to TO, inclusive.
3013 This is for the sake of peephole optimization, so assume
3014 that whatever these insns do will still be done by a new
3015 peephole insn that will replace them. */
3018 delete_for_peephole (from, to)
3019 register rtx from, to;
3021 register rtx insn = from;
3025 register rtx next = NEXT_INSN (insn);
3026 register rtx prev = PREV_INSN (insn);
3028 if (GET_CODE (insn) != NOTE)
3030 INSN_DELETED_P (insn) = 1;
3032 /* Patch this insn out of the chain. */
3033 /* We don't do this all at once, because we
3034 must preserve all NOTEs. */
3036 NEXT_INSN (prev) = next;
3039 PREV_INSN (next) = prev;
3047 /* Note that if TO is an unconditional jump
3048 we *do not* delete the BARRIER that follows,
3049 since the peephole that replaces this sequence
3050 is also an unconditional jump in that case. */
3053 /* We have determined that INSN is never reached, and are about to
3054 delete it. Print a warning if the user asked for one.
3056 To try to make this warning more useful, this should only be called
3057 once per basic block not reached, and it only warns when the basic
3058 block contains more than one line from the current function, and
3059 contains at least one operation. CSE and inlining can duplicate insns,
3060 so it's possible to get spurious warnings from this. */
3063 never_reached_warning (avoided_insn)
3067 rtx a_line_note = NULL;
3068 int two_avoided_lines = 0;
3069 int contains_insn = 0;
3071 if (! warn_notreached)
3074 /* Scan forwards, looking at LINE_NUMBER notes, until
3075 we hit a LABEL or we run out of insns. */
3077 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
3079 if (GET_CODE (insn) == CODE_LABEL)
3081 else if (GET_CODE (insn) == NOTE /* A line number note? */
3082 && NOTE_LINE_NUMBER (insn) >= 0)
3084 if (a_line_note == NULL)
3087 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
3088 != NOTE_LINE_NUMBER (insn));
3090 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
3093 if (two_avoided_lines && contains_insn)
3094 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
3095 NOTE_LINE_NUMBER (a_line_note),
3096 "will never be executed");
3099 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
3100 NLABEL as a return. Accrue modifications into the change group. */
3103 redirect_exp_1 (loc, olabel, nlabel, insn)
3108 register rtx x = *loc;
3109 register RTX_CODE code = GET_CODE (x);
3111 register const char *fmt;
3113 if (code == LABEL_REF)
3115 if (XEXP (x, 0) == olabel)
3119 n = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3121 n = gen_rtx_RETURN (VOIDmode);
3123 validate_change (insn, loc, n, 1);
3127 else if (code == RETURN && olabel == 0)
3129 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3130 if (loc == &PATTERN (insn))
3131 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
3132 validate_change (insn, loc, x, 1);
3136 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3137 && GET_CODE (SET_SRC (x)) == LABEL_REF
3138 && XEXP (SET_SRC (x), 0) == olabel)
3140 validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 1);
3144 fmt = GET_RTX_FORMAT (code);
3145 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3148 redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
3149 else if (fmt[i] == 'E')
3152 for (j = 0; j < XVECLEN (x, i); j++)
3153 redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
3158 /* Similar, but apply the change group and report success or failure. */
3161 redirect_exp (olabel, nlabel, insn)
3167 if (GET_CODE (PATTERN (insn)) == PARALLEL)
3168 loc = &XVECEXP (PATTERN (insn), 0, 0);
3170 loc = &PATTERN (insn);
3172 redirect_exp_1 (loc, olabel, nlabel, insn);
3173 if (num_validated_changes () == 0)
3176 return apply_change_group ();
3179 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
3180 the modifications into the change group. Return false if we did
3181 not see how to do that. */
3184 redirect_jump_1 (jump, nlabel)
3187 int ochanges = num_validated_changes ();
3190 if (GET_CODE (PATTERN (jump)) == PARALLEL)
3191 loc = &XVECEXP (PATTERN (jump), 0, 0);
3193 loc = &PATTERN (jump);
3195 redirect_exp_1 (loc, JUMP_LABEL (jump), nlabel, jump);
3196 return num_validated_changes () > ochanges;
3199 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
3200 jump target label is unused as a result, it and the code following
3203 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3206 The return value will be 1 if the change was made, 0 if it wasn't
3207 (this can only occur for NLABEL == 0). */
3210 redirect_jump (jump, nlabel, delete_unused)
3214 register rtx olabel = JUMP_LABEL (jump);
3216 if (nlabel == olabel)
3219 if (! redirect_exp (olabel, nlabel, jump))
3222 /* If this is an unconditional branch, delete it from the jump_chain of
3223 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3224 have UID's in range and JUMP_CHAIN is valid). */
3225 if (jump_chain && (simplejump_p (jump)
3226 || GET_CODE (PATTERN (jump)) == RETURN))
3228 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3230 delete_from_jump_chain (jump);
3231 if (label_index < max_jump_chain
3232 && INSN_UID (jump) < max_jump_chain)
3234 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3235 jump_chain[label_index] = jump;
3239 JUMP_LABEL (jump) = nlabel;
3241 ++LABEL_NUSES (nlabel);
3243 /* If we're eliding the jump over exception cleanups at the end of a
3244 function, move the function end note so that -Wreturn-type works. */
3245 if (olabel && nlabel
3246 && NEXT_INSN (olabel)
3247 && GET_CODE (NEXT_INSN (olabel)) == NOTE
3248 && NOTE_LINE_NUMBER (NEXT_INSN (olabel)) == NOTE_INSN_FUNCTION_END)
3249 emit_note_after (NOTE_INSN_FUNCTION_END, nlabel);
3251 if (olabel && --LABEL_NUSES (olabel) == 0 && delete_unused)
3252 delete_insn (olabel);
3257 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3258 Accrue the modifications into the change group. */
3264 register RTX_CODE code;
3265 rtx x = pc_set (insn);
3271 code = GET_CODE (x);
3273 if (code == IF_THEN_ELSE)
3275 register rtx comp = XEXP (x, 0);
3278 /* We can do this in two ways: The preferable way, which can only
3279 be done if this is not an integer comparison, is to reverse
3280 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3281 of the IF_THEN_ELSE. If we can't do either, fail. */
3283 if (can_reverse_comparison_p (comp, insn))
3285 validate_change (insn, &XEXP (x, 0),
3286 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
3287 GET_MODE (comp), XEXP (comp, 0),
3294 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3295 validate_change (insn, &XEXP (x, 2), tem, 1);
3301 /* Invert the jump condition of conditional jump insn, INSN.
3303 Return 1 if we can do so, 0 if we cannot find a way to do so that
3304 matches a pattern. */
3310 invert_exp_1 (insn);
3311 if (num_validated_changes () == 0)
3314 return apply_change_group ();
3317 /* Invert the condition of the jump JUMP, and make it jump to label
3318 NLABEL instead of where it jumps now. Accrue changes into the
3319 change group. Return false if we didn't see how to perform the
3320 inversion and redirection. */
3323 invert_jump_1 (jump, nlabel)
3328 ochanges = num_validated_changes ();
3329 invert_exp_1 (jump);
3330 if (num_validated_changes () == ochanges)
3333 return redirect_jump_1 (jump, nlabel);
3336 /* Invert the condition of the jump JUMP, and make it jump to label
3337 NLABEL instead of where it jumps now. Return true if successful. */
3340 invert_jump (jump, nlabel, delete_unused)
3344 /* We have to either invert the condition and change the label or
3345 do neither. Either operation could fail. We first try to invert
3346 the jump. If that succeeds, we try changing the label. If that fails,
3347 we invert the jump back to what it was. */
3349 if (! invert_exp (jump))
3352 if (redirect_jump (jump, nlabel, delete_unused))
3354 /* An inverted jump means that a probability taken becomes a
3355 probability not taken. Subtract the branch probability from the
3356 probability base to convert it back to a taken probability. */
3358 rtx note = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3360 XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
3365 if (! invert_exp (jump))
3366 /* This should just be putting it back the way it was. */
3372 /* Delete the instruction JUMP from any jump chain it might be on. */
3375 delete_from_jump_chain (jump)
3379 rtx olabel = JUMP_LABEL (jump);
3381 /* Handle unconditional jumps. */
3382 if (jump_chain && olabel != 0
3383 && INSN_UID (olabel) < max_jump_chain
3384 && simplejump_p (jump))
3385 index = INSN_UID (olabel);
3386 /* Handle return insns. */
3387 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3391 if (jump_chain[index] == jump)
3392 jump_chain[index] = jump_chain[INSN_UID (jump)];
3397 for (insn = jump_chain[index];
3399 insn = jump_chain[INSN_UID (insn)])
3400 if (jump_chain[INSN_UID (insn)] == jump)
3402 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3408 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3410 If the old jump target label (before the dispatch table) becomes unused,
3411 it and the dispatch table may be deleted. In that case, find the insn
3412 before the jump references that label and delete it and logical successors
3416 redirect_tablejump (jump, nlabel)
3419 register rtx olabel = JUMP_LABEL (jump);
3421 /* Add this jump to the jump_chain of NLABEL. */
3422 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3423 && INSN_UID (jump) < max_jump_chain)
3425 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3426 jump_chain[INSN_UID (nlabel)] = jump;
3429 PATTERN (jump) = gen_jump (nlabel);
3430 JUMP_LABEL (jump) = nlabel;
3431 ++LABEL_NUSES (nlabel);
3432 INSN_CODE (jump) = -1;
3434 if (--LABEL_NUSES (olabel) == 0)
3436 delete_labelref_insn (jump, olabel, 0);
3437 delete_insn (olabel);
3441 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3442 If we found one, delete it and then delete this insn if DELETE_THIS is
3443 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3446 delete_labelref_insn (insn, label, delete_this)
3453 if (GET_CODE (insn) != NOTE
3454 && reg_mentioned_p (label, PATTERN (insn)))
3465 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3466 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3480 /* Like rtx_equal_p except that it considers two REGs as equal
3481 if they renumber to the same value and considers two commutative
3482 operations to be the same if the order of the operands has been
3485 ??? Addition is not commutative on the PA due to the weird implicit
3486 space register selection rules for memory addresses. Therefore, we
3487 don't consider a + b == b + a.
3489 We could/should make this test a little tighter. Possibly only
3490 disabling it on the PA via some backend macro or only disabling this
3491 case when the PLUS is inside a MEM. */
3494 rtx_renumbered_equal_p (x, y)
3498 register RTX_CODE code = GET_CODE (x);
3499 register const char *fmt;
3504 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3505 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3506 && GET_CODE (SUBREG_REG (y)) == REG)))
3508 int reg_x = -1, reg_y = -1;
3509 int word_x = 0, word_y = 0;
3511 if (GET_MODE (x) != GET_MODE (y))
3514 /* If we haven't done any renumbering, don't
3515 make any assumptions. */
3516 if (reg_renumber == 0)
3517 return rtx_equal_p (x, y);
3521 reg_x = REGNO (SUBREG_REG (x));
3522 word_x = SUBREG_WORD (x);
3524 if (reg_renumber[reg_x] >= 0)
3526 reg_x = reg_renumber[reg_x] + word_x;
3534 if (reg_renumber[reg_x] >= 0)
3535 reg_x = reg_renumber[reg_x];
3538 if (GET_CODE (y) == SUBREG)
3540 reg_y = REGNO (SUBREG_REG (y));
3541 word_y = SUBREG_WORD (y);
3543 if (reg_renumber[reg_y] >= 0)
3545 reg_y = reg_renumber[reg_y];
3553 if (reg_renumber[reg_y] >= 0)
3554 reg_y = reg_renumber[reg_y];
3557 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3560 /* Now we have disposed of all the cases
3561 in which different rtx codes can match. */
3562 if (code != GET_CODE (y))
3574 return INTVAL (x) == INTVAL (y);
3577 /* We can't assume nonlocal labels have their following insns yet. */
3578 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3579 return XEXP (x, 0) == XEXP (y, 0);
3581 /* Two label-refs are equivalent if they point at labels
3582 in the same position in the instruction stream. */
3583 return (next_real_insn (XEXP (x, 0))
3584 == next_real_insn (XEXP (y, 0)));
3587 return XSTR (x, 0) == XSTR (y, 0);
3590 /* If we didn't match EQ equality above, they aren't the same. */
3597 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3599 if (GET_MODE (x) != GET_MODE (y))
3602 /* For commutative operations, the RTX match if the operand match in any
3603 order. Also handle the simple binary and unary cases without a loop.
3605 ??? Don't consider PLUS a commutative operator; see comments above. */
3606 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3608 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3609 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
3610 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
3611 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
3612 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3613 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3614 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
3615 else if (GET_RTX_CLASS (code) == '1')
3616 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
3618 /* Compare the elements. If any pair of corresponding elements
3619 fail to match, return 0 for the whole things. */
3621 fmt = GET_RTX_FORMAT (code);
3622 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3628 if (XWINT (x, i) != XWINT (y, i))
3633 if (XINT (x, i) != XINT (y, i))
3638 if (strcmp (XSTR (x, i), XSTR (y, i)))
3643 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3648 if (XEXP (x, i) != XEXP (y, i))
3655 if (XVECLEN (x, i) != XVECLEN (y, i))
3657 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3658 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3669 /* If X is a hard register or equivalent to one or a subregister of one,
3670 return the hard register number. If X is a pseudo register that was not
3671 assigned a hard register, return the pseudo register number. Otherwise,
3672 return -1. Any rtx is valid for X. */
3678 if (GET_CODE (x) == REG)
3680 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3681 return reg_renumber[REGNO (x)];
3684 if (GET_CODE (x) == SUBREG)
3686 int base = true_regnum (SUBREG_REG (x));
3687 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3688 return SUBREG_WORD (x) + base;
3693 /* Optimize code of the form:
3695 for (x = a[i]; x; ...)
3697 for (x = a[i]; x; ...)
3701 Loop optimize will change the above code into
3705 { ...; if (! (x = ...)) break; }
3708 { ...; if (! (x = ...)) break; }
3711 In general, if the first test fails, the program can branch
3712 directly to `foo' and skip the second try which is doomed to fail.
3713 We run this after loop optimization and before flow analysis. */
3715 /* When comparing the insn patterns, we track the fact that different
3716 pseudo-register numbers may have been used in each computation.
3717 The following array stores an equivalence -- same_regs[I] == J means
3718 that pseudo register I was used in the first set of tests in a context
3719 where J was used in the second set. We also count the number of such
3720 pending equivalences. If nonzero, the expressions really aren't the
3723 static int *same_regs;
3725 static int num_same_regs;
3727 /* Track any registers modified between the target of the first jump and
3728 the second jump. They never compare equal. */
3730 static char *modified_regs;
3732 /* Record if memory was modified. */
3734 static int modified_mem;
3736 /* Called via note_stores on each insn between the target of the first
3737 branch and the second branch. It marks any changed registers. */
3740 mark_modified_reg (dest, x, data)
3742 rtx x ATTRIBUTE_UNUSED;
3743 void *data ATTRIBUTE_UNUSED;
3748 if (GET_CODE (dest) == SUBREG)
3749 dest = SUBREG_REG (dest);
3751 if (GET_CODE (dest) == MEM)
3754 if (GET_CODE (dest) != REG)
3757 regno = REGNO (dest);
3758 if (regno >= FIRST_PSEUDO_REGISTER)
3759 modified_regs[regno] = 1;
3761 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3762 modified_regs[regno + i] = 1;
3765 /* F is the first insn in the chain of insns. */
3768 thread_jumps (f, max_reg, flag_before_loop)
3771 int flag_before_loop;
3773 /* Basic algorithm is to find a conditional branch,
3774 the label it may branch to, and the branch after
3775 that label. If the two branches test the same condition,
3776 walk back from both branch paths until the insn patterns
3777 differ, or code labels are hit. If we make it back to
3778 the target of the first branch, then we know that the first branch
3779 will either always succeed or always fail depending on the relative
3780 senses of the two branches. So adjust the first branch accordingly
3783 rtx label, b1, b2, t1, t2;
3784 enum rtx_code code1, code2;
3785 rtx b1op0, b1op1, b2op0, b2op1;
3790 /* Allocate register tables and quick-reset table. */
3791 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
3792 same_regs = (int *) xmalloc (max_reg * sizeof (int));
3793 all_reset = (int *) xmalloc (max_reg * sizeof (int));
3794 for (i = 0; i < max_reg; i++)
3801 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3805 /* Get to a candidate branch insn. */
3806 if (GET_CODE (b1) != JUMP_INSN
3807 || ! any_condjump_p (b1) || JUMP_LABEL (b1) == 0)
3810 bzero (modified_regs, max_reg * sizeof (char));
3813 bcopy ((char *) all_reset, (char *) same_regs,
3814 max_reg * sizeof (int));
3817 label = JUMP_LABEL (b1);
3819 /* Look for a branch after the target. Record any registers and
3820 memory modified between the target and the branch. Stop when we
3821 get to a label since we can't know what was changed there. */
3822 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
3824 if (GET_CODE (b2) == CODE_LABEL)
3827 else if (GET_CODE (b2) == JUMP_INSN)
3829 /* If this is an unconditional jump and is the only use of
3830 its target label, we can follow it. */
3831 if (any_uncondjump_p (b2)
3833 && JUMP_LABEL (b2) != 0
3834 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
3836 b2 = JUMP_LABEL (b2);
3843 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
3846 if (GET_CODE (b2) == CALL_INSN)
3849 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3850 if (call_used_regs[i] && ! fixed_regs[i]
3851 && i != STACK_POINTER_REGNUM
3852 && i != FRAME_POINTER_REGNUM
3853 && i != HARD_FRAME_POINTER_REGNUM
3854 && i != ARG_POINTER_REGNUM)
3855 modified_regs[i] = 1;
3858 note_stores (PATTERN (b2), mark_modified_reg, NULL);
3861 /* Check the next candidate branch insn from the label
3864 || GET_CODE (b2) != JUMP_INSN
3866 || !any_condjump_p (b2)
3867 || !onlyjump_p (b2))
3872 /* Get the comparison codes and operands, reversing the
3873 codes if appropriate. If we don't have comparison codes,
3874 we can't do anything. */
3875 b1op0 = XEXP (XEXP (SET_SRC (set), 0), 0);
3876 b1op1 = XEXP (XEXP (SET_SRC (set), 0), 1);
3877 code1 = GET_CODE (XEXP (SET_SRC (set), 0));
3878 if (XEXP (SET_SRC (set), 1) == pc_rtx)
3879 code1 = reverse_condition (code1);
3881 b2op0 = XEXP (XEXP (SET_SRC (set2), 0), 0);
3882 b2op1 = XEXP (XEXP (SET_SRC (set2), 0), 1);
3883 code2 = GET_CODE (XEXP (SET_SRC (set2), 0));
3884 if (XEXP (SET_SRC (set2), 1) == pc_rtx)
3885 code2 = reverse_condition (code2);
3887 /* If they test the same things and knowing that B1 branches
3888 tells us whether or not B2 branches, check if we
3889 can thread the branch. */
3890 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
3891 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
3892 && (comparison_dominates_p (code1, code2)
3893 || (can_reverse_comparison_p (XEXP (SET_SRC (set), 0), b1)
3894 && comparison_dominates_p (code1, reverse_condition (code2)))))
3897 t1 = prev_nonnote_insn (b1);
3898 t2 = prev_nonnote_insn (b2);
3900 while (t1 != 0 && t2 != 0)
3904 /* We have reached the target of the first branch.
3905 If there are no pending register equivalents,
3906 we know that this branch will either always
3907 succeed (if the senses of the two branches are
3908 the same) or always fail (if not). */
3911 if (num_same_regs != 0)
3914 if (comparison_dominates_p (code1, code2))
3915 new_label = JUMP_LABEL (b2);
3917 new_label = get_label_after (b2);
3919 if (JUMP_LABEL (b1) != new_label)
3921 rtx prev = PREV_INSN (new_label);
3923 if (flag_before_loop
3924 && GET_CODE (prev) == NOTE
3925 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
3927 /* Don't thread to the loop label. If a loop
3928 label is reused, loop optimization will
3929 be disabled for that loop. */
3930 new_label = gen_label_rtx ();
3931 emit_label_after (new_label, PREV_INSN (prev));
3933 changed |= redirect_jump (b1, new_label, 1);
3938 /* If either of these is not a normal insn (it might be
3939 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3940 have already been skipped above.) Similarly, fail
3941 if the insns are different. */
3942 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
3943 || recog_memoized (t1) != recog_memoized (t2)
3944 || ! rtx_equal_for_thread_p (PATTERN (t1),
3948 t1 = prev_nonnote_insn (t1);
3949 t2 = prev_nonnote_insn (t2);
3956 free (modified_regs);
3961 /* This is like RTX_EQUAL_P except that it knows about our handling of
3962 possibly equivalent registers and knows to consider volatile and
3963 modified objects as not equal.
3965 YINSN is the insn containing Y. */
3968 rtx_equal_for_thread_p (x, y, yinsn)
3974 register enum rtx_code code;
3975 register const char *fmt;
3977 code = GET_CODE (x);
3978 /* Rtx's of different codes cannot be equal. */
3979 if (code != GET_CODE (y))
3982 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
3983 (REG:SI x) and (REG:HI x) are NOT equivalent. */
3985 if (GET_MODE (x) != GET_MODE (y))
3988 /* For floating-point, consider everything unequal. This is a bit
3989 pessimistic, but this pass would only rarely do anything for FP
3991 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3992 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
3995 /* For commutative operations, the RTX match if the operand match in any
3996 order. Also handle the simple binary and unary cases without a loop. */
3997 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3998 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
3999 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4000 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4001 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4002 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4003 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4004 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4005 else if (GET_RTX_CLASS (code) == '1')
4006 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4008 /* Handle special-cases first. */
4012 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4015 /* If neither is user variable or hard register, check for possible
4017 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4018 || REGNO (x) < FIRST_PSEUDO_REGISTER
4019 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4022 if (same_regs[REGNO (x)] == -1)
4024 same_regs[REGNO (x)] = REGNO (y);
4027 /* If this is the first time we are seeing a register on the `Y'
4028 side, see if it is the last use. If not, we can't thread the
4029 jump, so mark it as not equivalent. */
4030 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4036 return (same_regs[REGNO (x)] == (int) REGNO (y));
4041 /* If memory modified or either volatile, not equivalent.
4042 Else, check address. */
4043 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4046 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4049 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4055 /* Cancel a pending `same_regs' if setting equivalenced registers.
4056 Then process source. */
4057 if (GET_CODE (SET_DEST (x)) == REG
4058 && GET_CODE (SET_DEST (y)) == REG)
4060 if (same_regs[REGNO (SET_DEST (x))] == (int) REGNO (SET_DEST (y)))
4062 same_regs[REGNO (SET_DEST (x))] = -1;
4065 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4069 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4072 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4075 return XEXP (x, 0) == XEXP (y, 0);
4078 return XSTR (x, 0) == XSTR (y, 0);
4087 fmt = GET_RTX_FORMAT (code);
4088 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4093 if (XWINT (x, i) != XWINT (y, i))
4099 if (XINT (x, i) != XINT (y, i))
4105 /* Two vectors must have the same length. */
4106 if (XVECLEN (x, i) != XVECLEN (y, i))
4109 /* And the corresponding elements must match. */
4110 for (j = 0; j < XVECLEN (x, i); j++)
4111 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4112 XVECEXP (y, i, j), yinsn) == 0)
4117 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4123 if (strcmp (XSTR (x, i), XSTR (y, i)))
4128 /* These are just backpointers, so they don't matter. */
4135 /* It is believed that rtx's at this level will never
4136 contain anything but integers and other rtx's,
4137 except for within LABEL_REFs and SYMBOL_REFs. */