1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997
3 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
59 #include "hard-reg-set.h"
61 #include "insn-config.h"
62 #include "insn-flags.h"
63 #include "insn-attr.h"
71 /* ??? Eventually must record somehow the labels used by jumps
72 from nested functions. */
73 /* Pre-record the next or previous real insn for each label?
74 No, this pass is very fast anyway. */
75 /* Condense consecutive labels?
76 This would make life analysis faster, maybe. */
77 /* Optimize jump y; x: ... y: jumpif... x?
78 Don't know if it is worth bothering with. */
79 /* Optimize two cases of conditional jump to conditional jump?
80 This can never delete any instruction or make anything dead,
81 or even change what is live at any point.
82 So perhaps let combiner do it. */
84 /* Vector indexed by uid.
85 For each CODE_LABEL, index by its uid to get first unconditional jump
86 that jumps to the label.
87 For each JUMP_INSN, index by its uid to get the next unconditional jump
88 that jumps to the same label.
89 Element 0 is the start of a chain of all return insns.
90 (It is safe to use element 0 because insn uid 0 is not used. */
92 static rtx *jump_chain;
94 /* Maximum index in jump_chain. */
96 static int max_jump_chain;
98 /* Indicates whether death notes are significant in cross jump analysis.
99 Normally they are not significant, because of A and B jump to C,
100 and R dies in A, it must die in B. But this might not be true after
101 stack register conversion, and we must compare death notes in that
104 static int cross_jump_death_matters = 0;
106 static int init_label_info PARAMS ((rtx));
107 static void delete_barrier_successors PARAMS ((rtx));
108 static void mark_all_labels PARAMS ((rtx, int));
109 static rtx delete_unreferenced_labels PARAMS ((rtx));
110 static void delete_noop_moves PARAMS ((rtx));
111 static int duplicate_loop_exit_test PARAMS ((rtx));
112 static void find_cross_jump PARAMS ((rtx, rtx, int, rtx *, rtx *));
113 static void do_cross_jump PARAMS ((rtx, rtx, rtx));
114 static int jump_back_p PARAMS ((rtx, rtx));
115 static int tension_vector_labels PARAMS ((rtx, int));
116 static void delete_computation PARAMS ((rtx));
117 static void redirect_exp_1 PARAMS ((rtx *, rtx, rtx, rtx));
118 static int redirect_exp PARAMS ((rtx, rtx, rtx));
119 static void invert_exp_1 PARAMS ((rtx));
120 static int invert_exp PARAMS ((rtx));
121 static void delete_from_jump_chain PARAMS ((rtx));
122 static int delete_labelref_insn PARAMS ((rtx, rtx, int));
123 static void mark_modified_reg PARAMS ((rtx, rtx, void *));
124 static void redirect_tablejump PARAMS ((rtx, rtx));
125 static void jump_optimize_1 PARAMS ((rtx, int, int, int, int, int));
126 static int returnjump_p_1 PARAMS ((rtx *, void *));
127 static void delete_prior_computation PARAMS ((rtx, rtx));
129 /* Main external entry point into the jump optimizer. See comments before
130 jump_optimize_1 for descriptions of the arguments. */
132 jump_optimize (f, cross_jump, noop_moves, after_regscan)
138 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0, 0);
141 /* Alternate entry into the jump optimizer. This entry point only rebuilds
142 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
145 rebuild_jump_labels (f)
148 jump_optimize_1 (f, 0, 0, 0, 1, 0);
151 /* Alternate entry into the jump optimizer. Do only trivial optimizations. */
154 jump_optimize_minimal (f)
157 jump_optimize_1 (f, 0, 0, 0, 0, 1);
160 /* Delete no-op jumps and optimize jumps to jumps
161 and jumps around jumps.
162 Delete unused labels and unreachable code.
164 If CROSS_JUMP is 1, detect matching code
165 before a jump and its destination and unify them.
166 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
168 If NOOP_MOVES is nonzero, delete no-op move insns.
170 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
171 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
173 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
174 and JUMP_LABEL field for jumping insns.
176 If `optimize' is zero, don't change any code,
177 just determine whether control drops off the end of the function.
178 This case occurs when we have -W and not -O.
179 It works because `delete_insn' checks the value of `optimize'
180 and refrains from actually deleting when that is 0.
182 If MINIMAL is nonzero, then we only perform trivial optimizations:
184 * Removal of unreachable code after BARRIERs.
185 * Removal of unreferenced CODE_LABELs.
186 * Removal of a jump to the next instruction.
187 * Removal of a conditional jump followed by an unconditional jump
188 to the same target as the conditional jump.
189 * Simplify a conditional jump around an unconditional jump.
190 * Simplify a jump to a jump.
191 * Delete extraneous line number notes.
195 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan,
196 mark_labels_only, minimal)
201 int mark_labels_only;
204 register rtx insn, next;
211 cross_jump_death_matters = (cross_jump == 2);
212 max_uid = init_label_info (f) + 1;
214 /* If we are performing cross jump optimizations, then initialize
215 tables mapping UIDs to EH regions to avoid incorrect movement
216 of insns from one EH region to another. */
217 if (flag_exceptions && cross_jump)
218 init_insn_eh_region (f, max_uid);
220 if (! mark_labels_only)
221 delete_barrier_successors (f);
223 /* Leave some extra room for labels and duplicate exit test insns
225 max_jump_chain = max_uid * 14 / 10;
226 jump_chain = (rtx *) xcalloc (max_jump_chain, sizeof (rtx));
228 mark_all_labels (f, cross_jump);
230 /* Keep track of labels used from static data; we don't track them
231 closely enough to delete them here, so make sure their reference
232 count doesn't drop to zero. */
234 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
235 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
236 LABEL_NUSES (XEXP (insn, 0))++;
238 check_exception_handler_labels ();
240 /* Keep track of labels used for marking handlers for exception
241 regions; they cannot usually be deleted. */
243 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
244 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
245 LABEL_NUSES (XEXP (insn, 0))++;
247 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
248 notes and recompute LABEL_NUSES. */
249 if (mark_labels_only)
253 exception_optimize ();
255 last_insn = delete_unreferenced_labels (f);
258 delete_noop_moves (f);
260 /* If we haven't yet gotten to reload and we have just run regscan,
261 delete any insn that sets a register that isn't used elsewhere.
262 This helps some of the optimizations below by having less insns
263 being jumped around. */
265 if (optimize && ! reload_completed && after_regscan)
266 for (insn = f; insn; insn = next)
268 rtx set = single_set (insn);
270 next = NEXT_INSN (insn);
272 if (set && GET_CODE (SET_DEST (set)) == REG
273 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
274 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
275 /* We use regno_last_note_uid so as not to delete the setting
276 of a reg that's used in notes. A subsequent optimization
277 might arrange to use that reg for real. */
278 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
279 && ! side_effects_p (SET_SRC (set))
280 && ! find_reg_note (insn, REG_RETVAL, 0)
281 /* An ADDRESSOF expression can turn into a use of the internal arg
282 pointer, so do not delete the initialization of the internal
283 arg pointer yet. If it is truly dead, flow will delete the
284 initializing insn. */
285 && SET_DEST (set) != current_function_internal_arg_pointer)
289 /* Now iterate optimizing jumps until nothing changes over one pass. */
291 old_max_reg = max_reg_num ();
296 for (insn = f; insn; insn = next)
299 rtx temp, temp1, temp2 = NULL_RTX;
300 rtx temp4 ATTRIBUTE_UNUSED;
302 int this_is_any_uncondjump;
303 int this_is_any_condjump;
304 int this_is_onlyjump;
306 next = NEXT_INSN (insn);
308 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
309 jump. Try to optimize by duplicating the loop exit test if so.
310 This is only safe immediately after regscan, because it uses
311 the values of regno_first_uid and regno_last_uid. */
312 if (after_regscan && GET_CODE (insn) == NOTE
313 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
314 && (temp1 = next_nonnote_insn (insn)) != 0
315 && any_uncondjump_p (temp1)
316 && onlyjump_p (temp1))
318 temp = PREV_INSN (insn);
319 if (duplicate_loop_exit_test (insn))
322 next = NEXT_INSN (temp);
327 if (GET_CODE (insn) != JUMP_INSN)
330 this_is_any_condjump = any_condjump_p (insn);
331 this_is_any_uncondjump = any_uncondjump_p (insn);
332 this_is_onlyjump = onlyjump_p (insn);
334 /* Tension the labels in dispatch tables. */
336 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
337 changed |= tension_vector_labels (PATTERN (insn), 0);
338 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
339 changed |= tension_vector_labels (PATTERN (insn), 1);
341 /* See if this jump goes to another jump and redirect if so. */
342 nlabel = follow_jumps (JUMP_LABEL (insn));
343 if (nlabel != JUMP_LABEL (insn))
344 changed |= redirect_jump (insn, nlabel, 1);
346 if (! optimize || minimal)
349 /* If a dispatch table always goes to the same place,
350 get rid of it and replace the insn that uses it. */
352 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
353 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
356 rtx pat = PATTERN (insn);
357 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
358 int len = XVECLEN (pat, diff_vec_p);
359 rtx dispatch = prev_real_insn (insn);
362 for (i = 0; i < len; i++)
363 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
364 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
369 && GET_CODE (dispatch) == JUMP_INSN
370 && JUMP_LABEL (dispatch) != 0
371 /* Don't mess with a casesi insn.
372 XXX according to the comment before computed_jump_p(),
373 all casesi insns should be a parallel of the jump
374 and a USE of a LABEL_REF. */
375 && ! ((set = single_set (dispatch)) != NULL
376 && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE))
377 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
379 redirect_tablejump (dispatch,
380 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
385 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
387 /* Detect jump to following insn. */
388 if (reallabelprev == insn
389 && (this_is_any_condjump || this_is_any_uncondjump)
392 next = next_real_insn (JUMP_LABEL (insn));
395 /* Remove the "inactive" but "real" insns (i.e. uses and
396 clobbers) in between here and there. */
398 while ((temp = next_real_insn (temp)) != next)
405 /* Detect a conditional jump going to the same place
406 as an immediately following unconditional jump. */
407 else if (this_is_any_condjump && this_is_onlyjump
408 && (temp = next_active_insn (insn)) != 0
409 && simplejump_p (temp)
410 && (next_active_insn (JUMP_LABEL (insn))
411 == next_active_insn (JUMP_LABEL (temp))))
413 /* Don't mess up test coverage analysis. */
415 if (flag_test_coverage && !reload_completed)
416 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
417 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
428 /* Detect a conditional jump jumping over an unconditional jump. */
430 else if (this_is_any_condjump
431 && reallabelprev != 0
432 && GET_CODE (reallabelprev) == JUMP_INSN
433 && prev_active_insn (reallabelprev) == insn
434 && no_labels_between_p (insn, reallabelprev)
435 && any_uncondjump_p (reallabelprev)
436 && onlyjump_p (reallabelprev))
438 /* When we invert the unconditional jump, we will be
439 decrementing the usage count of its old label.
440 Make sure that we don't delete it now because that
441 might cause the following code to be deleted. */
442 rtx prev_uses = prev_nonnote_insn (reallabelprev);
443 rtx prev_label = JUMP_LABEL (insn);
446 ++LABEL_NUSES (prev_label);
448 if (invert_jump (insn, JUMP_LABEL (reallabelprev), 1))
450 /* It is very likely that if there are USE insns before
451 this jump, they hold REG_DEAD notes. These REG_DEAD
452 notes are no longer valid due to this optimization,
453 and will cause the life-analysis that following passes
454 (notably delayed-branch scheduling) to think that
455 these registers are dead when they are not.
457 To prevent this trouble, we just remove the USE insns
458 from the insn chain. */
460 while (prev_uses && GET_CODE (prev_uses) == INSN
461 && GET_CODE (PATTERN (prev_uses)) == USE)
463 rtx useless = prev_uses;
464 prev_uses = prev_nonnote_insn (prev_uses);
465 delete_insn (useless);
468 delete_insn (reallabelprev);
472 /* We can now safely delete the label if it is unreferenced
473 since the delete_insn above has deleted the BARRIER. */
474 if (prev_label && --LABEL_NUSES (prev_label) == 0)
475 delete_insn (prev_label);
477 next = NEXT_INSN (insn);
480 /* If we have an unconditional jump preceded by a USE, try to put
481 the USE before the target and jump there. This simplifies many
482 of the optimizations below since we don't have to worry about
483 dealing with these USE insns. We only do this if the label
484 being branch to already has the identical USE or if code
485 never falls through to that label. */
487 else if (this_is_any_uncondjump
488 && (temp = prev_nonnote_insn (insn)) != 0
489 && GET_CODE (temp) == INSN
490 && GET_CODE (PATTERN (temp)) == USE
491 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
492 && (GET_CODE (temp1) == BARRIER
493 || (GET_CODE (temp1) == INSN
494 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
495 /* Don't do this optimization if we have a loop containing
496 only the USE instruction, and the loop start label has
497 a usage count of 1. This is because we will redo this
498 optimization everytime through the outer loop, and jump
499 opt will never exit. */
500 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
501 && temp2 == JUMP_LABEL (insn)
502 && LABEL_NUSES (temp2) == 1))
504 if (GET_CODE (temp1) == BARRIER)
506 emit_insn_after (PATTERN (temp), temp1);
507 temp1 = NEXT_INSN (temp1);
511 redirect_jump (insn, get_label_before (temp1), 1);
512 reallabelprev = prev_real_insn (temp1);
514 next = NEXT_INSN (insn);
518 /* Detect a conditional jump jumping over an unconditional trap. */
520 && this_is_any_condjump && this_is_onlyjump
521 && reallabelprev != 0
522 && GET_CODE (reallabelprev) == INSN
523 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
524 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
525 && prev_active_insn (reallabelprev) == insn
526 && no_labels_between_p (insn, reallabelprev)
527 && (temp2 = get_condition (insn, &temp4))
528 && can_reverse_comparison_p (temp2, insn))
530 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
531 XEXP (temp2, 0), XEXP (temp2, 1),
532 TRAP_CODE (PATTERN (reallabelprev)));
536 emit_insn_before (new, temp4);
537 delete_insn (reallabelprev);
543 /* Detect a jump jumping to an unconditional trap. */
544 else if (HAVE_trap && this_is_onlyjump
545 && (temp = next_active_insn (JUMP_LABEL (insn)))
546 && GET_CODE (temp) == INSN
547 && GET_CODE (PATTERN (temp)) == TRAP_IF
548 && (this_is_any_uncondjump
549 || (this_is_any_condjump
550 && (temp2 = get_condition (insn, &temp4)))))
552 rtx tc = TRAP_CONDITION (PATTERN (temp));
554 if (tc == const_true_rtx
555 || (! this_is_any_uncondjump && rtx_equal_p (temp2, tc)))
558 /* Replace an unconditional jump to a trap with a trap. */
559 if (this_is_any_uncondjump)
561 emit_barrier_after (emit_insn_before (gen_trap (), insn));
566 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
568 TRAP_CODE (PATTERN (temp)));
571 emit_insn_before (new, temp4);
577 /* If the trap condition and jump condition are mutually
578 exclusive, redirect the jump to the following insn. */
579 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
580 && this_is_any_condjump
581 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
582 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
583 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
584 && redirect_jump (insn, get_label_after (temp), 1))
593 /* Now that the jump has been tensioned,
594 try cross jumping: check for identical code
595 before the jump and before its target label. */
597 /* First, cross jumping of conditional jumps: */
599 if (cross_jump && condjump_p (insn))
601 rtx newjpos, newlpos;
602 rtx x = prev_real_insn (JUMP_LABEL (insn));
604 /* A conditional jump may be crossjumped
605 only if the place it jumps to follows
606 an opposing jump that comes back here. */
608 if (x != 0 && ! jump_back_p (x, insn))
609 /* We have no opposing jump;
610 cannot cross jump this insn. */
614 /* TARGET is nonzero if it is ok to cross jump
615 to code before TARGET. If so, see if matches. */
617 find_cross_jump (insn, x, 2,
622 do_cross_jump (insn, newjpos, newlpos);
623 /* Make the old conditional jump
624 into an unconditional one. */
625 SET_SRC (PATTERN (insn))
626 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
627 INSN_CODE (insn) = -1;
628 emit_barrier_after (insn);
629 /* Add to jump_chain unless this is a new label
630 whose UID is too large. */
631 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
633 jump_chain[INSN_UID (insn)]
634 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
635 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
642 /* Cross jumping of unconditional jumps:
643 a few differences. */
645 if (cross_jump && simplejump_p (insn))
647 rtx newjpos, newlpos;
652 /* TARGET is nonzero if it is ok to cross jump
653 to code before TARGET. If so, see if matches. */
654 find_cross_jump (insn, JUMP_LABEL (insn), 1,
657 /* If cannot cross jump to code before the label,
658 see if we can cross jump to another jump to
660 /* Try each other jump to this label. */
661 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
662 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
663 target != 0 && newjpos == 0;
664 target = jump_chain[INSN_UID (target)])
666 && JUMP_LABEL (target) == JUMP_LABEL (insn)
667 /* Ignore TARGET if it's deleted. */
668 && ! INSN_DELETED_P (target))
669 find_cross_jump (insn, target, 2,
674 do_cross_jump (insn, newjpos, newlpos);
680 /* This code was dead in the previous jump.c! */
681 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
683 /* Return insns all "jump to the same place"
684 so we can cross-jump between any two of them. */
686 rtx newjpos, newlpos, target;
690 /* If cannot cross jump to code before the label,
691 see if we can cross jump to another jump to
693 /* Try each other jump to this label. */
694 for (target = jump_chain[0];
695 target != 0 && newjpos == 0;
696 target = jump_chain[INSN_UID (target)])
698 && ! INSN_DELETED_P (target)
699 && GET_CODE (PATTERN (target)) == RETURN)
700 find_cross_jump (insn, target, 2,
705 do_cross_jump (insn, newjpos, newlpos);
716 /* Delete extraneous line number notes.
717 Note that two consecutive notes for different lines are not really
718 extraneous. There should be some indication where that line belonged,
719 even if it became empty. */
724 for (insn = f; insn; insn = NEXT_INSN (insn))
725 if (GET_CODE (insn) == NOTE)
727 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
728 /* Any previous line note was for the prologue; gdb wants a new
729 note after the prologue even if it is for the same line. */
730 last_note = NULL_RTX;
731 else if (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))
753 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
754 notes whose labels don't occur in the insn any more. Returns the
755 largest INSN_UID found. */
763 for (insn = f; insn; insn = NEXT_INSN (insn))
765 if (GET_CODE (insn) == CODE_LABEL)
766 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
767 else if (GET_CODE (insn) == JUMP_INSN)
768 JUMP_LABEL (insn) = 0;
769 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
773 for (note = REG_NOTES (insn); note; note = next)
775 next = XEXP (note, 1);
776 if (REG_NOTE_KIND (note) == REG_LABEL
777 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
778 remove_note (insn, note);
781 if (INSN_UID (insn) > largest_uid)
782 largest_uid = INSN_UID (insn);
788 /* Delete insns following barriers, up to next label.
790 Also delete no-op jumps created by gcse. */
793 delete_barrier_successors (f)
799 for (insn = f; insn;)
801 if (GET_CODE (insn) == BARRIER)
803 insn = NEXT_INSN (insn);
805 never_reached_warning (insn);
807 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
809 if (GET_CODE (insn) == NOTE
810 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
811 insn = NEXT_INSN (insn);
813 insn = delete_insn (insn);
815 /* INSN is now the code_label. */
818 /* Also remove (set (pc) (pc)) insns which can be created by
819 gcse. We eliminate such insns now to avoid having them
820 cause problems later. */
821 else if (GET_CODE (insn) == JUMP_INSN
822 && (set = pc_set (insn)) != NULL
823 && SET_SRC (set) == pc_rtx
824 && SET_DEST (set) == pc_rtx
825 && onlyjump_p (insn))
826 insn = delete_insn (insn);
829 insn = NEXT_INSN (insn);
833 /* Mark the label each jump jumps to.
834 Combine consecutive labels, and count uses of labels.
836 For each label, make a chain (using `jump_chain')
837 of all the *unconditional* jumps that jump to it;
838 also make a chain of all returns.
840 CROSS_JUMP indicates whether we are doing cross jumping
841 and if we are whether we will be paying attention to
842 death notes or not. */
845 mark_all_labels (f, cross_jump)
851 for (insn = f; insn; insn = NEXT_INSN (insn))
854 if (GET_CODE (insn) == CALL_INSN
855 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
857 mark_all_labels (XEXP (PATTERN (insn), 0), cross_jump);
858 mark_all_labels (XEXP (PATTERN (insn), 1), cross_jump);
859 mark_all_labels (XEXP (PATTERN (insn), 2), cross_jump);
863 mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
864 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
866 /* When we know the LABEL_REF contained in a REG used in
867 an indirect jump, we'll have a REG_LABEL note so that
868 flow can tell where it's going. */
869 if (JUMP_LABEL (insn) == 0)
871 rtx label_note = find_reg_note (insn, REG_LABEL, NULL_RTX);
874 /* But a LABEL_REF around the REG_LABEL note, so
875 that we can canonicalize it. */
876 rtx label_ref = gen_rtx_LABEL_REF (VOIDmode,
877 XEXP (label_note, 0));
879 mark_jump_label (label_ref, insn, cross_jump, 0);
880 XEXP (label_note, 0) = XEXP (label_ref, 0);
881 JUMP_LABEL (insn) = XEXP (label_note, 0);
884 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
886 jump_chain[INSN_UID (insn)]
887 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
888 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
890 if (GET_CODE (PATTERN (insn)) == RETURN)
892 jump_chain[INSN_UID (insn)] = jump_chain[0];
893 jump_chain[0] = insn;
899 /* Delete all labels already not referenced.
900 Also find and return the last insn. */
903 delete_unreferenced_labels (f)
906 rtx final = NULL_RTX;
909 for (insn = f; insn;)
911 if (GET_CODE (insn) == CODE_LABEL
912 && LABEL_NUSES (insn) == 0
913 && LABEL_ALTERNATE_NAME (insn) == NULL)
914 insn = delete_insn (insn);
918 insn = NEXT_INSN (insn);
925 /* Delete various simple forms of moves which have no necessary
929 delete_noop_moves (f)
934 for (insn = f; insn;)
936 next = NEXT_INSN (insn);
938 if (GET_CODE (insn) == INSN)
940 register rtx body = PATTERN (insn);
942 /* Detect and delete no-op move instructions
943 resulting from not allocating a parameter in a register. */
945 if (GET_CODE (body) == SET
946 && (SET_DEST (body) == SET_SRC (body)
947 || (GET_CODE (SET_DEST (body)) == MEM
948 && GET_CODE (SET_SRC (body)) == MEM
949 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
950 && ! (GET_CODE (SET_DEST (body)) == MEM
951 && MEM_VOLATILE_P (SET_DEST (body)))
952 && ! (GET_CODE (SET_SRC (body)) == MEM
953 && MEM_VOLATILE_P (SET_SRC (body))))
954 delete_computation (insn);
956 /* Detect and ignore no-op move instructions
957 resulting from smart or fortuitous register allocation. */
959 else if (GET_CODE (body) == SET)
961 int sreg = true_regnum (SET_SRC (body));
962 int dreg = true_regnum (SET_DEST (body));
964 if (sreg == dreg && sreg >= 0)
966 else if (sreg >= 0 && dreg >= 0)
969 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
970 sreg, NULL_PTR, dreg,
971 GET_MODE (SET_SRC (body)));
974 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
976 /* DREG may have been the target of a REG_DEAD note in
977 the insn which makes INSN redundant. If so, reorg
978 would still think it is dead. So search for such a
979 note and delete it if we find it. */
980 if (! find_regno_note (insn, REG_UNUSED, dreg))
981 for (trial = prev_nonnote_insn (insn);
982 trial && GET_CODE (trial) != CODE_LABEL;
983 trial = prev_nonnote_insn (trial))
984 if (find_regno_note (trial, REG_DEAD, dreg))
986 remove_death (dreg, trial);
990 /* Deleting insn could lose a death-note for SREG. */
991 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
993 /* Change this into a USE so that we won't emit
994 code for it, but still can keep the note. */
996 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
997 INSN_CODE (insn) = -1;
998 /* Remove all reg notes but the REG_DEAD one. */
999 REG_NOTES (insn) = trial;
1000 XEXP (trial, 1) = NULL_RTX;
1006 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
1007 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
1009 GET_MODE (SET_DEST (body))))
1011 /* This handles the case where we have two consecutive
1012 assignments of the same constant to pseudos that didn't
1013 get a hard reg. Each SET from the constant will be
1014 converted into a SET of the spill register and an
1015 output reload will be made following it. This produces
1016 two loads of the same constant into the same spill
1021 /* Look back for a death note for the first reg.
1022 If there is one, it is no longer accurate. */
1023 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
1025 if ((GET_CODE (in_insn) == INSN
1026 || GET_CODE (in_insn) == JUMP_INSN)
1027 && find_regno_note (in_insn, REG_DEAD, dreg))
1029 remove_death (dreg, in_insn);
1032 in_insn = PREV_INSN (in_insn);
1035 /* Delete the second load of the value. */
1039 else if (GET_CODE (body) == PARALLEL)
1041 /* If each part is a set between two identical registers or
1042 a USE or CLOBBER, delete the insn. */
1046 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
1048 tem = XVECEXP (body, 0, i);
1049 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
1052 if (GET_CODE (tem) != SET
1053 || (sreg = true_regnum (SET_SRC (tem))) < 0
1054 || (dreg = true_regnum (SET_DEST (tem))) < 0
1062 /* Also delete insns to store bit fields if they are no-ops. */
1063 /* Not worth the hair to detect this in the big-endian case. */
1064 else if (! BYTES_BIG_ENDIAN
1065 && GET_CODE (body) == SET
1066 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
1067 && XEXP (SET_DEST (body), 2) == const0_rtx
1068 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
1069 && ! (GET_CODE (SET_SRC (body)) == MEM
1070 && MEM_VOLATILE_P (SET_SRC (body))))
1077 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1078 jump. Assume that this unconditional jump is to the exit test code. If
1079 the code is sufficiently simple, make a copy of it before INSN,
1080 followed by a jump to the exit of the loop. Then delete the unconditional
1083 Return 1 if we made the change, else 0.
1085 This is only safe immediately after a regscan pass because it uses the
1086 values of regno_first_uid and regno_last_uid. */
1089 duplicate_loop_exit_test (loop_start)
1092 rtx insn, set, reg, p, link;
1093 rtx copy = 0, first_copy = 0;
1095 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
1097 int max_reg = max_reg_num ();
1100 /* Scan the exit code. We do not perform this optimization if any insn:
1104 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1105 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1106 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1109 We also do not do this if we find an insn with ASM_OPERANDS. While
1110 this restriction should not be necessary, copying an insn with
1111 ASM_OPERANDS can confuse asm_noperands in some cases.
1113 Also, don't do this if the exit code is more than 20 insns. */
1115 for (insn = exitcode;
1117 && ! (GET_CODE (insn) == NOTE
1118 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
1119 insn = NEXT_INSN (insn))
1121 switch (GET_CODE (insn))
1127 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
1128 a jump immediately after the loop start that branches outside
1129 the loop but within an outer loop, near the exit test.
1130 If we copied this exit test and created a phony
1131 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
1132 before the exit test look like these could be safely moved
1133 out of the loop even if they actually may be never executed.
1134 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
1136 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1137 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
1141 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1142 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
1143 /* If we were to duplicate this code, we would not move
1144 the BLOCK notes, and so debugging the moved code would
1145 be difficult. Thus, we only move the code with -O2 or
1152 /* The code below would grossly mishandle REG_WAS_0 notes,
1153 so get rid of them here. */
1154 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
1155 remove_note (insn, p);
1156 if (++num_insns > 20
1157 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1158 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
1166 /* Unless INSN is zero, we can do the optimization. */
1172 /* See if any insn sets a register only used in the loop exit code and
1173 not a user variable. If so, replace it with a new register. */
1174 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1175 if (GET_CODE (insn) == INSN
1176 && (set = single_set (insn)) != 0
1177 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
1178 || (GET_CODE (reg) == SUBREG
1179 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
1180 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
1181 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
1183 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
1184 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
1189 /* We can do the replacement. Allocate reg_map if this is the
1190 first replacement we found. */
1192 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
1194 REG_LOOP_TEST_P (reg) = 1;
1196 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
1200 /* Now copy each insn. */
1201 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1203 switch (GET_CODE (insn))
1206 copy = emit_barrier_before (loop_start);
1209 /* Only copy line-number notes. */
1210 if (NOTE_LINE_NUMBER (insn) >= 0)
1212 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
1213 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
1218 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
1220 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1222 mark_jump_label (PATTERN (copy), copy, 0, 0);
1224 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1226 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1227 if (REG_NOTE_KIND (link) != REG_LABEL)
1229 if (GET_CODE (link) == EXPR_LIST)
1231 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
1236 = copy_insn_1 (gen_rtx_INSN_LIST (REG_NOTE_KIND (link),
1241 if (reg_map && REG_NOTES (copy))
1242 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1246 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)),
1249 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1250 mark_jump_label (PATTERN (copy), copy, 0, 0);
1251 if (REG_NOTES (insn))
1253 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
1255 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1258 /* If this is a simple jump, add it to the jump chain. */
1260 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
1261 && simplejump_p (copy))
1263 jump_chain[INSN_UID (copy)]
1264 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1265 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1273 /* Record the first insn we copied. We need it so that we can
1274 scan the copied insns for new pseudo registers. */
1279 /* Now clean up by emitting a jump to the end label and deleting the jump
1280 at the start of the loop. */
1281 if (! copy || GET_CODE (copy) != BARRIER)
1283 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
1286 /* Record the first insn we copied. We need it so that we can
1287 scan the copied insns for new pseudo registers. This may not
1288 be strictly necessary since we should have copied at least one
1289 insn above. But I am going to be safe. */
1293 mark_jump_label (PATTERN (copy), copy, 0, 0);
1294 if (INSN_UID (copy) < max_jump_chain
1295 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
1297 jump_chain[INSN_UID (copy)]
1298 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1299 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1301 emit_barrier_before (loop_start);
1304 /* Now scan from the first insn we copied to the last insn we copied
1305 (copy) for new pseudo registers. Do this after the code to jump to
1306 the end label since that might create a new pseudo too. */
1307 reg_scan_update (first_copy, copy, max_reg);
1309 /* Mark the exit code as the virtual top of the converted loop. */
1310 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
1312 delete_insn (next_nonnote_insn (loop_start));
1321 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
1322 eh-beg, eh-end notes between START and END out before START. Assume that
1323 END is not such a note. START may be such a note. Returns the value
1324 of the new starting insn, which may be different if the original start
1328 squeeze_notes (start, end)
1334 for (insn = start; insn != end; insn = next)
1336 next = NEXT_INSN (insn);
1337 if (GET_CODE (insn) == NOTE
1338 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
1339 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1340 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1341 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
1342 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
1343 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP
1344 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1345 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1351 rtx prev = PREV_INSN (insn);
1352 PREV_INSN (insn) = PREV_INSN (start);
1353 NEXT_INSN (insn) = start;
1354 NEXT_INSN (PREV_INSN (insn)) = insn;
1355 PREV_INSN (NEXT_INSN (insn)) = insn;
1356 NEXT_INSN (prev) = next;
1357 PREV_INSN (next) = prev;
1365 /* Compare the instructions before insn E1 with those before E2
1366 to find an opportunity for cross jumping.
1367 (This means detecting identical sequences of insns followed by
1368 jumps to the same place, or followed by a label and a jump
1369 to that label, and replacing one with a jump to the other.)
1371 Assume E1 is a jump that jumps to label E2
1372 (that is not always true but it might as well be).
1373 Find the longest possible equivalent sequences
1374 and store the first insns of those sequences into *F1 and *F2.
1375 Store zero there if no equivalent preceding instructions are found.
1377 We give up if we find a label in stream 1.
1378 Actually we could transfer that label into stream 2. */
1381 find_cross_jump (e1, e2, minimum, f1, f2)
1386 register rtx i1 = e1, i2 = e2;
1387 register rtx p1, p2;
1390 rtx last1 = 0, last2 = 0;
1391 rtx afterlast1 = 0, afterlast2 = 0;
1398 i1 = prev_nonnote_insn (i1);
1400 i2 = PREV_INSN (i2);
1401 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
1402 i2 = PREV_INSN (i2);
1407 /* Don't allow the range of insns preceding E1 or E2
1408 to include the other (E2 or E1). */
1409 if (i2 == e1 || i1 == e2)
1412 /* If we will get to this code by jumping, those jumps will be
1413 tensioned to go directly to the new label (before I2),
1414 so this cross-jumping won't cost extra. So reduce the minimum. */
1415 if (GET_CODE (i1) == CODE_LABEL)
1421 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
1424 /* Avoid moving insns across EH regions if either of the insns
1427 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
1428 && !in_same_eh_region (i1, i2))
1434 /* If this is a CALL_INSN, compare register usage information.
1435 If we don't check this on stack register machines, the two
1436 CALL_INSNs might be merged leaving reg-stack.c with mismatching
1437 numbers of stack registers in the same basic block.
1438 If we don't check this on machines with delay slots, a delay slot may
1439 be filled that clobbers a parameter expected by the subroutine.
1441 ??? We take the simple route for now and assume that if they're
1442 equal, they were constructed identically. */
1444 if (GET_CODE (i1) == CALL_INSN
1445 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1446 CALL_INSN_FUNCTION_USAGE (i2)))
1450 /* If cross_jump_death_matters is not 0, the insn's mode
1451 indicates whether or not the insn contains any stack-like
1454 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
1456 /* If register stack conversion has already been done, then
1457 death notes must also be compared before it is certain that
1458 the two instruction streams match. */
1461 HARD_REG_SET i1_regset, i2_regset;
1463 CLEAR_HARD_REG_SET (i1_regset);
1464 CLEAR_HARD_REG_SET (i2_regset);
1466 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
1467 if (REG_NOTE_KIND (note) == REG_DEAD
1468 && STACK_REG_P (XEXP (note, 0)))
1469 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
1471 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1472 if (REG_NOTE_KIND (note) == REG_DEAD
1473 && STACK_REG_P (XEXP (note, 0)))
1474 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1476 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
1485 /* Don't allow old-style asm or volatile extended asms to be accepted
1486 for cross jumping purposes. It is conceptually correct to allow
1487 them, since cross-jumping preserves the dynamic instruction order
1488 even though it is changing the static instruction order. However,
1489 if an asm is being used to emit an assembler pseudo-op, such as
1490 the MIPS `.set reorder' pseudo-op, then the static instruction order
1491 matters and it must be preserved. */
1492 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
1493 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
1494 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
1497 if (lose || GET_CODE (p1) != GET_CODE (p2)
1498 || ! rtx_renumbered_equal_p (p1, p2))
1500 /* The following code helps take care of G++ cleanups. */
1504 if (!lose && GET_CODE (p1) == GET_CODE (p2)
1505 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
1506 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
1507 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
1508 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
1509 /* If the equivalences are not to a constant, they may
1510 reference pseudos that no longer exist, so we can't
1512 && CONSTANT_P (XEXP (equiv1, 0))
1513 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1515 rtx s1 = single_set (i1);
1516 rtx s2 = single_set (i2);
1517 if (s1 != 0 && s2 != 0
1518 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
1520 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
1521 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
1522 if (! rtx_renumbered_equal_p (p1, p2))
1524 else if (apply_change_group ())
1529 /* Insns fail to match; cross jumping is limited to the following
1533 /* Don't allow the insn after a compare to be shared by
1534 cross-jumping unless the compare is also shared.
1535 Here, if either of these non-matching insns is a compare,
1536 exclude the following insn from possible cross-jumping. */
1537 if (sets_cc0_p (p1) || sets_cc0_p (p2))
1538 last1 = afterlast1, last2 = afterlast2, ++minimum;
1541 /* If cross-jumping here will feed a jump-around-jump
1542 optimization, this jump won't cost extra, so reduce
1544 if (GET_CODE (i1) == JUMP_INSN
1546 && prev_real_insn (JUMP_LABEL (i1)) == e1)
1552 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
1554 /* Ok, this insn is potentially includable in a cross-jump here. */
1555 afterlast1 = last1, afterlast2 = last2;
1556 last1 = i1, last2 = i2, --minimum;
1560 if (minimum <= 0 && last1 != 0 && last1 != e1)
1561 *f1 = last1, *f2 = last2;
1565 do_cross_jump (insn, newjpos, newlpos)
1566 rtx insn, newjpos, newlpos;
1568 /* Find an existing label at this point
1569 or make a new one if there is none. */
1570 register rtx label = get_label_before (newlpos);
1572 /* Make the same jump insn jump to the new point. */
1573 if (GET_CODE (PATTERN (insn)) == RETURN)
1575 /* Remove from jump chain of returns. */
1576 delete_from_jump_chain (insn);
1577 /* Change the insn. */
1578 PATTERN (insn) = gen_jump (label);
1579 INSN_CODE (insn) = -1;
1580 JUMP_LABEL (insn) = label;
1581 LABEL_NUSES (label)++;
1582 /* Add to new the jump chain. */
1583 if (INSN_UID (label) < max_jump_chain
1584 && INSN_UID (insn) < max_jump_chain)
1586 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
1587 jump_chain[INSN_UID (label)] = insn;
1591 redirect_jump (insn, label, 1);
1593 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
1594 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
1595 the NEWJPOS stream. */
1597 while (newjpos != insn)
1601 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
1602 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
1603 || REG_NOTE_KIND (lnote) == REG_EQUIV)
1604 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
1605 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
1606 remove_note (newlpos, lnote);
1608 delete_insn (newjpos);
1609 newjpos = next_real_insn (newjpos);
1610 newlpos = next_real_insn (newlpos);
1614 /* Return the label before INSN, or put a new label there. */
1617 get_label_before (insn)
1622 /* Find an existing label at this point
1623 or make a new one if there is none. */
1624 label = prev_nonnote_insn (insn);
1626 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1628 rtx prev = PREV_INSN (insn);
1630 label = gen_label_rtx ();
1631 emit_label_after (label, prev);
1632 LABEL_NUSES (label) = 0;
1637 /* Return the label after INSN, or put a new label there. */
1640 get_label_after (insn)
1645 /* Find an existing label at this point
1646 or make a new one if there is none. */
1647 label = next_nonnote_insn (insn);
1649 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1651 label = gen_label_rtx ();
1652 emit_label_after (label, insn);
1653 LABEL_NUSES (label) = 0;
1658 /* Return 1 if INSN is a jump that jumps to right after TARGET
1659 only on the condition that TARGET itself would drop through.
1660 Assumes that TARGET is a conditional jump. */
1663 jump_back_p (insn, target)
1667 enum rtx_code codei, codet;
1670 if (! any_condjump_p (insn)
1671 || any_uncondjump_p (target)
1672 || target != prev_real_insn (JUMP_LABEL (insn)))
1674 set = pc_set (insn);
1675 tset = pc_set (target);
1677 cinsn = XEXP (SET_SRC (set), 0);
1678 ctarget = XEXP (SET_SRC (tset), 0);
1680 codei = GET_CODE (cinsn);
1681 codet = GET_CODE (ctarget);
1683 if (XEXP (SET_SRC (set), 1) == pc_rtx)
1685 if (! can_reverse_comparison_p (cinsn, insn))
1687 codei = reverse_condition (codei);
1690 if (XEXP (SET_SRC (tset), 2) == pc_rtx)
1692 if (! can_reverse_comparison_p (ctarget, target))
1694 codet = reverse_condition (codet);
1697 return (codei == codet
1698 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
1699 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
1702 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
1703 return non-zero if it is safe to reverse this comparison. It is if our
1704 floating-point is not IEEE, if this is an NE or EQ comparison, or if
1705 this is known to be an integer comparison. */
1708 can_reverse_comparison_p (comparison, insn)
1714 /* If this is not actually a comparison, we can't reverse it. */
1715 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
1718 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
1719 /* If this is an NE comparison, it is safe to reverse it to an EQ
1720 comparison and vice versa, even for floating point. If no operands
1721 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
1722 always false and NE is always true, so the reversal is also valid. */
1724 || GET_CODE (comparison) == NE
1725 || GET_CODE (comparison) == EQ)
1728 arg0 = XEXP (comparison, 0);
1730 /* Make sure ARG0 is one of the actual objects being compared. If we
1731 can't do this, we can't be sure the comparison can be reversed.
1733 Handle cc0 and a MODE_CC register. */
1734 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
1742 /* First see if the condition code mode alone if enough to say we can
1743 reverse the condition. If not, then search backwards for a set of
1744 ARG0. We do not need to check for an insn clobbering it since valid
1745 code will contain set a set with no intervening clobber. But
1746 stop when we reach a label. */
1747 #ifdef REVERSIBLE_CC_MODE
1748 if (GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC
1749 && REVERSIBLE_CC_MODE (GET_MODE (arg0)))
1756 for (prev = prev_nonnote_insn (insn);
1757 prev != 0 && GET_CODE (prev) != CODE_LABEL;
1758 prev = prev_nonnote_insn (prev))
1759 if ((set = single_set (prev)) != 0
1760 && rtx_equal_p (SET_DEST (set), arg0))
1762 arg0 = SET_SRC (set);
1764 if (GET_CODE (arg0) == COMPARE)
1765 arg0 = XEXP (arg0, 0);
1770 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
1771 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
1772 return (GET_CODE (arg0) == CONST_INT
1773 || (GET_MODE (arg0) != VOIDmode
1774 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
1775 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
1778 /* Given an rtx-code for a comparison, return the code for the negated
1779 comparison. If no such code exists, return UNKNOWN.
1781 WATCH OUT! reverse_condition is not safe to use on a jump that might
1782 be acting on the results of an IEEE floating point comparison, because
1783 of the special treatment of non-signaling nans in comparisons.
1784 Use can_reverse_comparison_p to be sure. */
1787 reverse_condition (code)
1830 /* Similar, but we're allowed to generate unordered comparisons, which
1831 makes it safe for IEEE floating-point. Of course, we have to recognize
1832 that the target will support them too... */
1835 reverse_condition_maybe_unordered (code)
1838 /* Non-IEEE formats don't have unordered conditions. */
1839 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
1840 return reverse_condition (code);
1886 /* Similar, but return the code when two operands of a comparison are swapped.
1887 This IS safe for IEEE floating-point. */
1890 swap_condition (code)
1933 /* Given a comparison CODE, return the corresponding unsigned comparison.
1934 If CODE is an equality comparison or already an unsigned comparison,
1935 CODE is returned. */
1938 unsigned_condition (code)
1965 /* Similarly, return the signed version of a comparison. */
1968 signed_condition (code)
1995 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
1996 truth of CODE1 implies the truth of CODE2. */
1999 comparison_dominates_p (code1, code2)
2000 enum rtx_code code1, code2;
2008 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
2009 || code2 == ORDERED)
2014 if (code2 == LE || code2 == NE || code2 == ORDERED)
2019 if (code2 == GE || code2 == NE || code2 == ORDERED)
2025 if (code2 == ORDERED)
2030 if (code2 == NE || code2 == ORDERED)
2035 if (code2 == LEU || code2 == NE)
2040 if (code2 == GEU || code2 == NE)
2056 /* Return 1 if INSN is an unconditional jump and nothing else. */
2062 return (GET_CODE (insn) == JUMP_INSN
2063 && GET_CODE (PATTERN (insn)) == SET
2064 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2065 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2068 /* Return nonzero if INSN is a (possibly) conditional jump
2071 Use this function is deprecated, since we need to support combined
2072 branch and compare insns. Use any_condjump_p instead whenever possible. */
2078 register rtx x = PATTERN (insn);
2080 if (GET_CODE (x) != SET
2081 || GET_CODE (SET_DEST (x)) != PC)
2085 if (GET_CODE (x) == LABEL_REF)
2088 return (GET_CODE (x) == IF_THEN_ELSE
2089 && ((GET_CODE (XEXP (x, 2)) == PC
2090 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
2091 || GET_CODE (XEXP (x, 1)) == RETURN))
2092 || (GET_CODE (XEXP (x, 1)) == PC
2093 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
2094 || GET_CODE (XEXP (x, 2)) == RETURN))));
2099 /* Return nonzero if INSN is a (possibly) conditional jump inside a
2102 Use this function is deprecated, since we need to support combined
2103 branch and compare insns. Use any_condjump_p instead whenever possible. */
2106 condjump_in_parallel_p (insn)
2109 register rtx x = PATTERN (insn);
2111 if (GET_CODE (x) != PARALLEL)
2114 x = XVECEXP (x, 0, 0);
2116 if (GET_CODE (x) != SET)
2118 if (GET_CODE (SET_DEST (x)) != PC)
2120 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2122 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2124 if (XEXP (SET_SRC (x), 2) == pc_rtx
2125 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2126 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2128 if (XEXP (SET_SRC (x), 1) == pc_rtx
2129 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2130 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2135 /* Return set of PC, otherwise NULL. */
2142 if (GET_CODE (insn) != JUMP_INSN)
2144 pat = PATTERN (insn);
2146 /* The set is allowed to appear either as the insn pattern or
2147 the first set in a PARALLEL. */
2148 if (GET_CODE (pat) == PARALLEL)
2149 pat = XVECEXP (pat, 0, 0);
2150 if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
2156 /* Return true when insn is an unconditional direct jump,
2157 possibly bundled inside a PARALLEL. */
2160 any_uncondjump_p (insn)
2163 rtx x = pc_set (insn);
2166 if (GET_CODE (SET_SRC (x)) != LABEL_REF)
2171 /* Return true when insn is a conditional jump. This function works for
2172 instructions containing PC sets in PARALLELs. The instruction may have
2173 various other effects so before removing the jump you must verify
2176 Note that unlike condjump_p it returns false for unconditional jumps. */
2179 any_condjump_p (insn)
2182 rtx x = pc_set (insn);
2187 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2190 a = GET_CODE (XEXP (SET_SRC (x), 1));
2191 b = GET_CODE (XEXP (SET_SRC (x), 2));
2193 return ((b == PC && (a == LABEL_REF || a == RETURN))
2194 || (a == PC && (b == LABEL_REF || b == RETURN)));
2197 /* Return the label of a conditional jump. */
2200 condjump_label (insn)
2203 rtx x = pc_set (insn);
2208 if (GET_CODE (x) == LABEL_REF)
2210 if (GET_CODE (x) != IF_THEN_ELSE)
2212 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
2214 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
2219 /* Return true if INSN is a (possibly conditional) return insn. */
2222 returnjump_p_1 (loc, data)
2224 void *data ATTRIBUTE_UNUSED;
2227 return x && GET_CODE (x) == RETURN;
2234 if (GET_CODE (insn) != JUMP_INSN)
2236 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
2239 /* Return true if INSN is a jump that only transfers control and
2248 if (GET_CODE (insn) != JUMP_INSN)
2251 set = single_set (insn);
2254 if (GET_CODE (SET_DEST (set)) != PC)
2256 if (side_effects_p (SET_SRC (set)))
2264 /* Return 1 if X is an RTX that does nothing but set the condition codes
2265 and CLOBBER or USE registers.
2266 Return -1 if X does explicitly set the condition codes,
2267 but also does other things. */
2271 rtx x ATTRIBUTE_UNUSED;
2273 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2275 if (GET_CODE (x) == PARALLEL)
2279 int other_things = 0;
2280 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2282 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2283 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2285 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2288 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2294 /* Follow any unconditional jump at LABEL;
2295 return the ultimate label reached by any such chain of jumps.
2296 If LABEL is not followed by a jump, return LABEL.
2297 If the chain loops or we can't find end, return LABEL,
2298 since that tells caller to avoid changing the insn.
2300 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2301 a USE or CLOBBER. */
2304 follow_jumps (label)
2309 register rtx value = label;
2314 && (insn = next_active_insn (value)) != 0
2315 && GET_CODE (insn) == JUMP_INSN
2316 && ((JUMP_LABEL (insn) != 0 && any_uncondjump_p (insn)
2317 && onlyjump_p (insn))
2318 || GET_CODE (PATTERN (insn)) == RETURN)
2319 && (next = NEXT_INSN (insn))
2320 && GET_CODE (next) == BARRIER);
2323 /* Don't chain through the insn that jumps into a loop
2324 from outside the loop,
2325 since that would create multiple loop entry jumps
2326 and prevent loop optimization. */
2328 if (!reload_completed)
2329 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2330 if (GET_CODE (tem) == NOTE
2331 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
2332 /* ??? Optional. Disables some optimizations, but makes
2333 gcov output more accurate with -O. */
2334 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
2337 /* If we have found a cycle, make the insn jump to itself. */
2338 if (JUMP_LABEL (insn) == label)
2341 tem = next_active_insn (JUMP_LABEL (insn));
2342 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
2343 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
2346 value = JUMP_LABEL (insn);
2353 /* Assuming that field IDX of X is a vector of label_refs,
2354 replace each of them by the ultimate label reached by it.
2355 Return nonzero if a change is made.
2356 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2359 tension_vector_labels (x, idx)
2365 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2367 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2368 register rtx nlabel = follow_jumps (olabel);
2369 if (nlabel && nlabel != olabel)
2371 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2372 ++LABEL_NUSES (nlabel);
2373 if (--LABEL_NUSES (olabel) == 0)
2374 delete_insn (olabel);
2381 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2382 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2383 in INSN, then store one of them in JUMP_LABEL (INSN).
2384 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2385 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2386 Also, when there are consecutive labels, canonicalize on the last of them.
2388 Note that two labels separated by a loop-beginning note
2389 must be kept distinct if we have not yet done loop-optimization,
2390 because the gap between them is where loop-optimize
2391 will want to move invariant code to. CROSS_JUMP tells us
2392 that loop-optimization is done with.
2394 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2395 two labels distinct if they are separated by only USE or CLOBBER insns. */
2398 mark_jump_label (x, insn, cross_jump, in_mem)
2404 register RTX_CODE code = GET_CODE (x);
2406 register const char *fmt;
2428 /* If this is a constant-pool reference, see if it is a label. */
2429 if (CONSTANT_POOL_ADDRESS_P (x))
2430 mark_jump_label (get_pool_constant (x), insn, cross_jump, in_mem);
2435 rtx label = XEXP (x, 0);
2440 /* Ignore remaining references to unreachable labels that
2441 have been deleted. */
2442 if (GET_CODE (label) == NOTE
2443 && NOTE_LINE_NUMBER (label) == NOTE_INSN_DELETED_LABEL)
2446 if (GET_CODE (label) != CODE_LABEL)
2449 /* Ignore references to labels of containing functions. */
2450 if (LABEL_REF_NONLOCAL_P (x))
2453 /* If there are other labels following this one,
2454 replace it with the last of the consecutive labels. */
2455 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
2457 if (GET_CODE (next) == CODE_LABEL)
2459 else if (cross_jump && GET_CODE (next) == INSN
2460 && (GET_CODE (PATTERN (next)) == USE
2461 || GET_CODE (PATTERN (next)) == CLOBBER))
2463 else if (GET_CODE (next) != NOTE)
2465 else if (! cross_jump
2466 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
2467 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
2468 /* ??? Optional. Disables some optimizations, but
2469 makes gcov output more accurate with -O. */
2470 || (flag_test_coverage
2471 && NOTE_LINE_NUMBER (next) > 0)))
2475 XEXP (x, 0) = label;
2476 if (! insn || ! INSN_DELETED_P (insn))
2477 ++LABEL_NUSES (label);
2481 if (GET_CODE (insn) == JUMP_INSN)
2482 JUMP_LABEL (insn) = label;
2484 /* If we've changed OLABEL and we had a REG_LABEL note
2485 for it, update it as well. */
2486 else if (label != olabel
2487 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
2488 XEXP (note, 0) = label;
2490 /* Otherwise, add a REG_LABEL note for LABEL unless there already
2492 else if (! find_reg_note (insn, REG_LABEL, label))
2494 /* This code used to ignore labels which refered to dispatch
2495 tables to avoid flow.c generating worse code.
2497 However, in the presense of global optimizations like
2498 gcse which call find_basic_blocks without calling
2499 life_analysis, not recording such labels will lead
2500 to compiler aborts because of inconsistencies in the
2501 flow graph. So we go ahead and record the label.
2503 It may also be the case that the optimization argument
2504 is no longer valid because of the more accurate cfg
2505 we build in find_basic_blocks -- it no longer pessimizes
2506 code when it finds a REG_LABEL note. */
2507 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
2514 /* Do walk the labels in a vector, but not the first operand of an
2515 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2518 if (! INSN_DELETED_P (insn))
2520 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
2522 for (i = 0; i < XVECLEN (x, eltnum); i++)
2523 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX,
2524 cross_jump, in_mem);
2532 fmt = GET_RTX_FORMAT (code);
2533 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2536 mark_jump_label (XEXP (x, i), insn, cross_jump, in_mem);
2537 else if (fmt[i] == 'E')
2540 for (j = 0; j < XVECLEN (x, i); j++)
2541 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump, in_mem);
2546 /* If all INSN does is set the pc, delete it,
2547 and delete the insn that set the condition codes for it
2548 if that's what the previous thing was. */
2554 register rtx set = single_set (insn);
2556 if (set && GET_CODE (SET_DEST (set)) == PC)
2557 delete_computation (insn);
2560 /* Verify INSN is a BARRIER and delete it. */
2563 delete_barrier (insn)
2566 if (GET_CODE (insn) != BARRIER)
2572 /* Recursively delete prior insns that compute the value (used only by INSN
2573 which the caller is deleting) stored in the register mentioned by NOTE
2574 which is a REG_DEAD note associated with INSN. */
2577 delete_prior_computation (note, insn)
2582 rtx reg = XEXP (note, 0);
2584 for (our_prev = prev_nonnote_insn (insn);
2585 our_prev && (GET_CODE (our_prev) == INSN
2586 || GET_CODE (our_prev) == CALL_INSN);
2587 our_prev = prev_nonnote_insn (our_prev))
2589 rtx pat = PATTERN (our_prev);
2591 /* If we reach a CALL which is not calling a const function
2592 or the callee pops the arguments, then give up. */
2593 if (GET_CODE (our_prev) == CALL_INSN
2594 && (! CONST_CALL_P (our_prev)
2595 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
2598 /* If we reach a SEQUENCE, it is too complex to try to
2599 do anything with it, so give up. */
2600 if (GET_CODE (pat) == SEQUENCE)
2603 if (GET_CODE (pat) == USE
2604 && GET_CODE (XEXP (pat, 0)) == INSN)
2605 /* reorg creates USEs that look like this. We leave them
2606 alone because reorg needs them for its own purposes. */
2609 if (reg_set_p (reg, pat))
2611 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
2614 if (GET_CODE (pat) == PARALLEL)
2616 /* If we find a SET of something else, we can't
2621 for (i = 0; i < XVECLEN (pat, 0); i++)
2623 rtx part = XVECEXP (pat, 0, i);
2625 if (GET_CODE (part) == SET
2626 && SET_DEST (part) != reg)
2630 if (i == XVECLEN (pat, 0))
2631 delete_computation (our_prev);
2633 else if (GET_CODE (pat) == SET
2634 && GET_CODE (SET_DEST (pat)) == REG)
2636 int dest_regno = REGNO (SET_DEST (pat));
2639 + (dest_regno < FIRST_PSEUDO_REGISTER
2640 ? HARD_REGNO_NREGS (dest_regno,
2641 GET_MODE (SET_DEST (pat))) : 1));
2642 int regno = REGNO (reg);
2645 + (regno < FIRST_PSEUDO_REGISTER
2646 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1));
2648 if (dest_regno >= regno
2649 && dest_endregno <= endregno)
2650 delete_computation (our_prev);
2652 /* We may have a multi-word hard register and some, but not
2653 all, of the words of the register are needed in subsequent
2654 insns. Write REG_UNUSED notes for those parts that were not
2656 else if (dest_regno <= regno
2657 && dest_endregno >= endregno)
2661 REG_NOTES (our_prev)
2662 = gen_rtx_EXPR_LIST (REG_UNUSED, reg,
2663 REG_NOTES (our_prev));
2665 for (i = dest_regno; i < dest_endregno; i++)
2666 if (! find_regno_note (our_prev, REG_UNUSED, i))
2669 if (i == dest_endregno)
2670 delete_computation (our_prev);
2677 /* If PAT references the register that dies here, it is an
2678 additional use. Hence any prior SET isn't dead. However, this
2679 insn becomes the new place for the REG_DEAD note. */
2680 if (reg_overlap_mentioned_p (reg, pat))
2682 XEXP (note, 1) = REG_NOTES (our_prev);
2683 REG_NOTES (our_prev) = note;
2689 /* Delete INSN and recursively delete insns that compute values used only
2690 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2691 If we are running before flow.c, we need do nothing since flow.c will
2692 delete dead code. We also can't know if the registers being used are
2693 dead or not at this point.
2695 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2696 nothing other than set a register that dies in this insn, we can delete
2699 On machines with CC0, if CC0 is used in this insn, we may be able to
2700 delete the insn that set it. */
2703 delete_computation (insn)
2709 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
2711 rtx prev = prev_nonnote_insn (insn);
2712 /* We assume that at this stage
2713 CC's are always set explicitly
2714 and always immediately before the jump that
2715 will use them. So if the previous insn
2716 exists to set the CC's, delete it
2717 (unless it performs auto-increments, etc.). */
2718 if (prev && GET_CODE (prev) == INSN
2719 && sets_cc0_p (PATTERN (prev)))
2721 if (sets_cc0_p (PATTERN (prev)) > 0
2722 && ! side_effects_p (PATTERN (prev)))
2723 delete_computation (prev);
2725 /* Otherwise, show that cc0 won't be used. */
2726 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
2727 cc0_rtx, REG_NOTES (prev));
2732 for (note = REG_NOTES (insn); note; note = next)
2734 next = XEXP (note, 1);
2736 if (REG_NOTE_KIND (note) != REG_DEAD
2737 /* Verify that the REG_NOTE is legitimate. */
2738 || GET_CODE (XEXP (note, 0)) != REG)
2741 delete_prior_computation (note, insn);
2747 /* Delete insn INSN from the chain of insns and update label ref counts.
2748 May delete some following insns as a consequence; may even delete
2749 a label elsewhere and insns that follow it.
2751 Returns the first insn after INSN that was not deleted. */
2757 register rtx next = NEXT_INSN (insn);
2758 register rtx prev = PREV_INSN (insn);
2759 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
2760 register int dont_really_delete = 0;
2763 while (next && INSN_DELETED_P (next))
2764 next = NEXT_INSN (next);
2766 /* This insn is already deleted => return first following nondeleted. */
2767 if (INSN_DELETED_P (insn))
2771 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2773 /* Don't delete user-declared labels. When optimizing, convert them
2774 to special NOTEs instead. When not optimizing, leave them alone. */
2775 if (was_code_label && LABEL_NAME (insn) != 0)
2778 dont_really_delete = 1;
2779 else if (! dont_really_delete)
2781 const char *name = LABEL_NAME (insn);
2782 PUT_CODE (insn, NOTE);
2783 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
2784 NOTE_SOURCE_FILE (insn) = name;
2785 dont_really_delete = 1;
2789 /* Mark this insn as deleted. */
2790 INSN_DELETED_P (insn) = 1;
2792 /* If this is an unconditional jump, delete it from the jump chain. */
2793 if (simplejump_p (insn))
2794 delete_from_jump_chain (insn);
2796 /* If instruction is followed by a barrier,
2797 delete the barrier too. */
2799 if (next != 0 && GET_CODE (next) == BARRIER)
2801 INSN_DELETED_P (next) = 1;
2802 next = NEXT_INSN (next);
2805 /* Patch out INSN (and the barrier if any) */
2807 if (! dont_really_delete)
2811 NEXT_INSN (prev) = next;
2812 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
2813 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
2814 XVECLEN (PATTERN (prev), 0) - 1)) = next;
2819 PREV_INSN (next) = prev;
2820 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
2821 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
2824 if (prev && NEXT_INSN (prev) == 0)
2825 set_last_insn (prev);
2828 /* If deleting a jump, decrement the count of the label,
2829 and delete the label if it is now unused. */
2831 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
2833 rtx lab = JUMP_LABEL (insn), lab_next;
2835 if (--LABEL_NUSES (lab) == 0)
2837 /* This can delete NEXT or PREV,
2838 either directly if NEXT is JUMP_LABEL (INSN),
2839 or indirectly through more levels of jumps. */
2842 /* I feel a little doubtful about this loop,
2843 but I see no clean and sure alternative way
2844 to find the first insn after INSN that is not now deleted.
2845 I hope this works. */
2846 while (next && INSN_DELETED_P (next))
2847 next = NEXT_INSN (next);
2850 else if ((lab_next = next_nonnote_insn (lab)) != NULL
2851 && GET_CODE (lab_next) == JUMP_INSN
2852 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
2853 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
2855 /* If we're deleting the tablejump, delete the dispatch table.
2856 We may not be able to kill the label immediately preceeding
2857 just yet, as it might be referenced in code leading up to
2859 delete_insn (lab_next);
2863 /* Likewise if we're deleting a dispatch table. */
2865 if (GET_CODE (insn) == JUMP_INSN
2866 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2867 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2869 rtx pat = PATTERN (insn);
2870 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2871 int len = XVECLEN (pat, diff_vec_p);
2873 for (i = 0; i < len; i++)
2874 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
2875 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
2876 while (next && INSN_DELETED_P (next))
2877 next = NEXT_INSN (next);
2881 /* Likewise for an ordinary INSN / CALL_INSN with a REG_LABEL note. */
2882 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2883 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2884 if (REG_NOTE_KIND (note) == REG_LABEL
2885 /* This could also be a NOTE_INSN_DELETED_LABEL note. */
2886 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2887 if (--LABEL_NUSES (XEXP (note, 0)) == 0)
2888 delete_insn (XEXP (note, 0));
2890 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
2891 prev = PREV_INSN (prev);
2893 /* If INSN was a label and a dispatch table follows it,
2894 delete the dispatch table. The tablejump must have gone already.
2895 It isn't useful to fall through into a table. */
2898 && NEXT_INSN (insn) != 0
2899 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
2900 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
2901 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
2902 next = delete_insn (NEXT_INSN (insn));
2904 /* If INSN was a label, delete insns following it if now unreachable. */
2906 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
2908 register RTX_CODE code;
2910 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
2911 || code == NOTE || code == BARRIER
2912 || (code == CODE_LABEL && INSN_DELETED_P (next))))
2915 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
2916 next = NEXT_INSN (next);
2917 /* Keep going past other deleted labels to delete what follows. */
2918 else if (code == CODE_LABEL && INSN_DELETED_P (next))
2919 next = NEXT_INSN (next);
2921 /* Note: if this deletes a jump, it can cause more
2922 deletion of unreachable code, after a different label.
2923 As long as the value from this recursive call is correct,
2924 this invocation functions correctly. */
2925 next = delete_insn (next);
2932 /* Advance from INSN till reaching something not deleted
2933 then return that. May return INSN itself. */
2936 next_nondeleted_insn (insn)
2939 while (INSN_DELETED_P (insn))
2940 insn = NEXT_INSN (insn);
2944 /* Delete a range of insns from FROM to TO, inclusive.
2945 This is for the sake of peephole optimization, so assume
2946 that whatever these insns do will still be done by a new
2947 peephole insn that will replace them. */
2950 delete_for_peephole (from, to)
2951 register rtx from, to;
2953 register rtx insn = from;
2957 register rtx next = NEXT_INSN (insn);
2958 register rtx prev = PREV_INSN (insn);
2960 if (GET_CODE (insn) != NOTE)
2962 INSN_DELETED_P (insn) = 1;
2964 /* Patch this insn out of the chain. */
2965 /* We don't do this all at once, because we
2966 must preserve all NOTEs. */
2968 NEXT_INSN (prev) = next;
2971 PREV_INSN (next) = prev;
2979 /* Note that if TO is an unconditional jump
2980 we *do not* delete the BARRIER that follows,
2981 since the peephole that replaces this sequence
2982 is also an unconditional jump in that case. */
2985 /* We have determined that INSN is never reached, and are about to
2986 delete it. Print a warning if the user asked for one.
2988 To try to make this warning more useful, this should only be called
2989 once per basic block not reached, and it only warns when the basic
2990 block contains more than one line from the current function, and
2991 contains at least one operation. CSE and inlining can duplicate insns,
2992 so it's possible to get spurious warnings from this. */
2995 never_reached_warning (avoided_insn)
2999 rtx a_line_note = NULL;
3000 int two_avoided_lines = 0;
3001 int contains_insn = 0;
3003 if (! warn_notreached)
3006 /* Scan forwards, looking at LINE_NUMBER notes, until
3007 we hit a LABEL or we run out of insns. */
3009 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
3011 if (GET_CODE (insn) == CODE_LABEL)
3013 else if (GET_CODE (insn) == NOTE /* A line number note? */
3014 && NOTE_LINE_NUMBER (insn) >= 0)
3016 if (a_line_note == NULL)
3019 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
3020 != NOTE_LINE_NUMBER (insn));
3022 else if (INSN_P (insn))
3025 if (two_avoided_lines && contains_insn)
3026 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
3027 NOTE_LINE_NUMBER (a_line_note),
3028 "will never be executed");
3031 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
3032 NLABEL as a return. Accrue modifications into the change group. */
3035 redirect_exp_1 (loc, olabel, nlabel, insn)
3040 register rtx x = *loc;
3041 register RTX_CODE code = GET_CODE (x);
3043 register const char *fmt;
3045 if (code == LABEL_REF)
3047 if (XEXP (x, 0) == olabel)
3051 n = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3053 n = gen_rtx_RETURN (VOIDmode);
3055 validate_change (insn, loc, n, 1);
3059 else if (code == RETURN && olabel == 0)
3061 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3062 if (loc == &PATTERN (insn))
3063 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
3064 validate_change (insn, loc, x, 1);
3068 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3069 && GET_CODE (SET_SRC (x)) == LABEL_REF
3070 && XEXP (SET_SRC (x), 0) == olabel)
3072 validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 1);
3076 fmt = GET_RTX_FORMAT (code);
3077 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3080 redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
3081 else if (fmt[i] == 'E')
3084 for (j = 0; j < XVECLEN (x, i); j++)
3085 redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
3090 /* Similar, but apply the change group and report success or failure. */
3093 redirect_exp (olabel, nlabel, insn)
3099 if (GET_CODE (PATTERN (insn)) == PARALLEL)
3100 loc = &XVECEXP (PATTERN (insn), 0, 0);
3102 loc = &PATTERN (insn);
3104 redirect_exp_1 (loc, olabel, nlabel, insn);
3105 if (num_validated_changes () == 0)
3108 return apply_change_group ();
3111 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
3112 the modifications into the change group. Return false if we did
3113 not see how to do that. */
3116 redirect_jump_1 (jump, nlabel)
3119 int ochanges = num_validated_changes ();
3122 if (GET_CODE (PATTERN (jump)) == PARALLEL)
3123 loc = &XVECEXP (PATTERN (jump), 0, 0);
3125 loc = &PATTERN (jump);
3127 redirect_exp_1 (loc, JUMP_LABEL (jump), nlabel, jump);
3128 return num_validated_changes () > ochanges;
3131 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
3132 jump target label is unused as a result, it and the code following
3135 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3138 The return value will be 1 if the change was made, 0 if it wasn't
3139 (this can only occur for NLABEL == 0). */
3142 redirect_jump (jump, nlabel, delete_unused)
3146 register rtx olabel = JUMP_LABEL (jump);
3148 if (nlabel == olabel)
3151 if (! redirect_exp (olabel, nlabel, jump))
3154 /* If this is an unconditional branch, delete it from the jump_chain of
3155 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3156 have UID's in range and JUMP_CHAIN is valid). */
3157 if (jump_chain && (simplejump_p (jump)
3158 || GET_CODE (PATTERN (jump)) == RETURN))
3160 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3162 delete_from_jump_chain (jump);
3163 if (label_index < max_jump_chain
3164 && INSN_UID (jump) < max_jump_chain)
3166 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3167 jump_chain[label_index] = jump;
3171 JUMP_LABEL (jump) = nlabel;
3173 ++LABEL_NUSES (nlabel);
3175 /* If we're eliding the jump over exception cleanups at the end of a
3176 function, move the function end note so that -Wreturn-type works. */
3177 if (olabel && nlabel
3178 && NEXT_INSN (olabel)
3179 && GET_CODE (NEXT_INSN (olabel)) == NOTE
3180 && NOTE_LINE_NUMBER (NEXT_INSN (olabel)) == NOTE_INSN_FUNCTION_END)
3181 emit_note_after (NOTE_INSN_FUNCTION_END, nlabel);
3183 if (olabel && --LABEL_NUSES (olabel) == 0 && delete_unused)
3184 delete_insn (olabel);
3189 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3190 Accrue the modifications into the change group. */
3196 register RTX_CODE code;
3197 rtx x = pc_set (insn);
3203 code = GET_CODE (x);
3205 if (code == IF_THEN_ELSE)
3207 register rtx comp = XEXP (x, 0);
3210 /* We can do this in two ways: The preferable way, which can only
3211 be done if this is not an integer comparison, is to reverse
3212 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3213 of the IF_THEN_ELSE. If we can't do either, fail. */
3215 if (can_reverse_comparison_p (comp, insn))
3217 validate_change (insn, &XEXP (x, 0),
3218 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
3219 GET_MODE (comp), XEXP (comp, 0),
3226 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3227 validate_change (insn, &XEXP (x, 2), tem, 1);
3233 /* Invert the jump condition of conditional jump insn, INSN.
3235 Return 1 if we can do so, 0 if we cannot find a way to do so that
3236 matches a pattern. */
3242 invert_exp_1 (insn);
3243 if (num_validated_changes () == 0)
3246 return apply_change_group ();
3249 /* Invert the condition of the jump JUMP, and make it jump to label
3250 NLABEL instead of where it jumps now. Accrue changes into the
3251 change group. Return false if we didn't see how to perform the
3252 inversion and redirection. */
3255 invert_jump_1 (jump, nlabel)
3260 ochanges = num_validated_changes ();
3261 invert_exp_1 (jump);
3262 if (num_validated_changes () == ochanges)
3265 return redirect_jump_1 (jump, nlabel);
3268 /* Invert the condition of the jump JUMP, and make it jump to label
3269 NLABEL instead of where it jumps now. Return true if successful. */
3272 invert_jump (jump, nlabel, delete_unused)
3276 /* We have to either invert the condition and change the label or
3277 do neither. Either operation could fail. We first try to invert
3278 the jump. If that succeeds, we try changing the label. If that fails,
3279 we invert the jump back to what it was. */
3281 if (! invert_exp (jump))
3284 if (redirect_jump (jump, nlabel, delete_unused))
3286 /* An inverted jump means that a probability taken becomes a
3287 probability not taken. Subtract the branch probability from the
3288 probability base to convert it back to a taken probability. */
3290 rtx note = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3292 XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
3297 if (! invert_exp (jump))
3298 /* This should just be putting it back the way it was. */
3304 /* Delete the instruction JUMP from any jump chain it might be on. */
3307 delete_from_jump_chain (jump)
3311 rtx olabel = JUMP_LABEL (jump);
3313 /* Handle unconditional jumps. */
3314 if (jump_chain && olabel != 0
3315 && INSN_UID (olabel) < max_jump_chain
3316 && simplejump_p (jump))
3317 index = INSN_UID (olabel);
3318 /* Handle return insns. */
3319 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3324 if (jump_chain[index] == jump)
3325 jump_chain[index] = jump_chain[INSN_UID (jump)];
3330 for (insn = jump_chain[index];
3332 insn = jump_chain[INSN_UID (insn)])
3333 if (jump_chain[INSN_UID (insn)] == jump)
3335 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3341 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3343 If the old jump target label (before the dispatch table) becomes unused,
3344 it and the dispatch table may be deleted. In that case, find the insn
3345 before the jump references that label and delete it and logical successors
3349 redirect_tablejump (jump, nlabel)
3352 register rtx olabel = JUMP_LABEL (jump);
3353 rtx *notep, note, next;
3355 /* Add this jump to the jump_chain of NLABEL. */
3356 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3357 && INSN_UID (jump) < max_jump_chain)
3359 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3360 jump_chain[INSN_UID (nlabel)] = jump;
3363 for (notep = ®_NOTES (jump), note = *notep; note; note = next)
3365 next = XEXP (note, 1);
3367 if (REG_NOTE_KIND (note) != REG_DEAD
3368 /* Verify that the REG_NOTE is legitimate. */
3369 || GET_CODE (XEXP (note, 0)) != REG
3370 || ! reg_mentioned_p (XEXP (note, 0), PATTERN (jump)))
3371 notep = &XEXP (note, 1);
3374 delete_prior_computation (note, jump);
3379 PATTERN (jump) = gen_jump (nlabel);
3380 JUMP_LABEL (jump) = nlabel;
3381 ++LABEL_NUSES (nlabel);
3382 INSN_CODE (jump) = -1;
3384 if (--LABEL_NUSES (olabel) == 0)
3386 delete_labelref_insn (jump, olabel, 0);
3387 delete_insn (olabel);
3391 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3392 If we found one, delete it and then delete this insn if DELETE_THIS is
3393 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3396 delete_labelref_insn (insn, label, delete_this)
3403 if (GET_CODE (insn) != NOTE
3404 && reg_mentioned_p (label, PATTERN (insn)))
3415 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3416 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3430 /* Like rtx_equal_p except that it considers two REGs as equal
3431 if they renumber to the same value and considers two commutative
3432 operations to be the same if the order of the operands has been
3435 ??? Addition is not commutative on the PA due to the weird implicit
3436 space register selection rules for memory addresses. Therefore, we
3437 don't consider a + b == b + a.
3439 We could/should make this test a little tighter. Possibly only
3440 disabling it on the PA via some backend macro or only disabling this
3441 case when the PLUS is inside a MEM. */
3444 rtx_renumbered_equal_p (x, y)
3448 register RTX_CODE code = GET_CODE (x);
3449 register const char *fmt;
3454 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3455 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3456 && GET_CODE (SUBREG_REG (y)) == REG)))
3458 int reg_x = -1, reg_y = -1;
3459 int word_x = 0, word_y = 0;
3461 if (GET_MODE (x) != GET_MODE (y))
3464 /* If we haven't done any renumbering, don't
3465 make any assumptions. */
3466 if (reg_renumber == 0)
3467 return rtx_equal_p (x, y);
3471 reg_x = REGNO (SUBREG_REG (x));
3472 word_x = SUBREG_WORD (x);
3474 if (reg_renumber[reg_x] >= 0)
3476 reg_x = reg_renumber[reg_x] + word_x;
3484 if (reg_renumber[reg_x] >= 0)
3485 reg_x = reg_renumber[reg_x];
3488 if (GET_CODE (y) == SUBREG)
3490 reg_y = REGNO (SUBREG_REG (y));
3491 word_y = SUBREG_WORD (y);
3493 if (reg_renumber[reg_y] >= 0)
3495 reg_y = reg_renumber[reg_y];
3503 if (reg_renumber[reg_y] >= 0)
3504 reg_y = reg_renumber[reg_y];
3507 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3510 /* Now we have disposed of all the cases
3511 in which different rtx codes can match. */
3512 if (code != GET_CODE (y))
3524 return INTVAL (x) == INTVAL (y);
3527 /* We can't assume nonlocal labels have their following insns yet. */
3528 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3529 return XEXP (x, 0) == XEXP (y, 0);
3531 /* Two label-refs are equivalent if they point at labels
3532 in the same position in the instruction stream. */
3533 return (next_real_insn (XEXP (x, 0))
3534 == next_real_insn (XEXP (y, 0)));
3537 return XSTR (x, 0) == XSTR (y, 0);
3540 /* If we didn't match EQ equality above, they aren't the same. */
3547 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3549 if (GET_MODE (x) != GET_MODE (y))
3552 /* For commutative operations, the RTX match if the operand match in any
3553 order. Also handle the simple binary and unary cases without a loop.
3555 ??? Don't consider PLUS a commutative operator; see comments above. */
3556 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3558 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3559 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
3560 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
3561 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
3562 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3563 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3564 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
3565 else if (GET_RTX_CLASS (code) == '1')
3566 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
3568 /* Compare the elements. If any pair of corresponding elements
3569 fail to match, return 0 for the whole things. */
3571 fmt = GET_RTX_FORMAT (code);
3572 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3578 if (XWINT (x, i) != XWINT (y, i))
3583 if (XINT (x, i) != XINT (y, i))
3588 if (strcmp (XSTR (x, i), XSTR (y, i)))
3593 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3598 if (XEXP (x, i) != XEXP (y, i))
3605 if (XVECLEN (x, i) != XVECLEN (y, i))
3607 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3608 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3619 /* If X is a hard register or equivalent to one or a subregister of one,
3620 return the hard register number. If X is a pseudo register that was not
3621 assigned a hard register, return the pseudo register number. Otherwise,
3622 return -1. Any rtx is valid for X. */
3628 if (GET_CODE (x) == REG)
3630 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3631 return reg_renumber[REGNO (x)];
3634 if (GET_CODE (x) == SUBREG)
3636 int base = true_regnum (SUBREG_REG (x));
3637 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3638 return SUBREG_WORD (x) + base;
3643 /* Optimize code of the form:
3645 for (x = a[i]; x; ...)
3647 for (x = a[i]; x; ...)
3651 Loop optimize will change the above code into
3655 { ...; if (! (x = ...)) break; }
3658 { ...; if (! (x = ...)) break; }
3661 In general, if the first test fails, the program can branch
3662 directly to `foo' and skip the second try which is doomed to fail.
3663 We run this after loop optimization and before flow analysis. */
3665 /* When comparing the insn patterns, we track the fact that different
3666 pseudo-register numbers may have been used in each computation.
3667 The following array stores an equivalence -- same_regs[I] == J means
3668 that pseudo register I was used in the first set of tests in a context
3669 where J was used in the second set. We also count the number of such
3670 pending equivalences. If nonzero, the expressions really aren't the
3673 static int *same_regs;
3675 static int num_same_regs;
3677 /* Track any registers modified between the target of the first jump and
3678 the second jump. They never compare equal. */
3680 static char *modified_regs;
3682 /* Record if memory was modified. */
3684 static int modified_mem;
3686 /* Called via note_stores on each insn between the target of the first
3687 branch and the second branch. It marks any changed registers. */
3690 mark_modified_reg (dest, x, data)
3692 rtx x ATTRIBUTE_UNUSED;
3693 void *data ATTRIBUTE_UNUSED;
3698 if (GET_CODE (dest) == SUBREG)
3699 dest = SUBREG_REG (dest);
3701 if (GET_CODE (dest) == MEM)
3704 if (GET_CODE (dest) != REG)
3707 regno = REGNO (dest);
3708 if (regno >= FIRST_PSEUDO_REGISTER)
3709 modified_regs[regno] = 1;
3711 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3712 modified_regs[regno + i] = 1;
3715 /* F is the first insn in the chain of insns. */
3718 thread_jumps (f, max_reg, flag_before_loop)
3721 int flag_before_loop;
3723 /* Basic algorithm is to find a conditional branch,
3724 the label it may branch to, and the branch after
3725 that label. If the two branches test the same condition,
3726 walk back from both branch paths until the insn patterns
3727 differ, or code labels are hit. If we make it back to
3728 the target of the first branch, then we know that the first branch
3729 will either always succeed or always fail depending on the relative
3730 senses of the two branches. So adjust the first branch accordingly
3733 rtx label, b1, b2, t1, t2;
3734 enum rtx_code code1, code2;
3735 rtx b1op0, b1op1, b2op0, b2op1;
3740 /* Allocate register tables and quick-reset table. */
3741 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
3742 same_regs = (int *) xmalloc (max_reg * sizeof (int));
3743 all_reset = (int *) xmalloc (max_reg * sizeof (int));
3744 for (i = 0; i < max_reg; i++)
3751 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3756 /* Get to a candidate branch insn. */
3757 if (GET_CODE (b1) != JUMP_INSN
3758 || ! any_condjump_p (b1) || JUMP_LABEL (b1) == 0)
3761 memset (modified_regs, 0, max_reg * sizeof (char));
3764 memcpy (same_regs, all_reset, max_reg * sizeof (int));
3767 label = JUMP_LABEL (b1);
3769 /* Look for a branch after the target. Record any registers and
3770 memory modified between the target and the branch. Stop when we
3771 get to a label since we can't know what was changed there. */
3772 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
3774 if (GET_CODE (b2) == CODE_LABEL)
3777 else if (GET_CODE (b2) == JUMP_INSN)
3779 /* If this is an unconditional jump and is the only use of
3780 its target label, we can follow it. */
3781 if (any_uncondjump_p (b2)
3783 && JUMP_LABEL (b2) != 0
3784 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
3786 b2 = JUMP_LABEL (b2);
3793 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
3796 if (GET_CODE (b2) == CALL_INSN)
3799 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3800 if (call_used_regs[i] && ! fixed_regs[i]
3801 && i != STACK_POINTER_REGNUM
3802 && i != FRAME_POINTER_REGNUM
3803 && i != HARD_FRAME_POINTER_REGNUM
3804 && i != ARG_POINTER_REGNUM)
3805 modified_regs[i] = 1;
3808 note_stores (PATTERN (b2), mark_modified_reg, NULL);
3811 /* Check the next candidate branch insn from the label
3814 || GET_CODE (b2) != JUMP_INSN
3816 || !any_condjump_p (b2)
3817 || !onlyjump_p (b2))
3822 /* Get the comparison codes and operands, reversing the
3823 codes if appropriate. If we don't have comparison codes,
3824 we can't do anything. */
3825 b1op0 = XEXP (XEXP (SET_SRC (set), 0), 0);
3826 b1op1 = XEXP (XEXP (SET_SRC (set), 0), 1);
3827 code1 = GET_CODE (XEXP (SET_SRC (set), 0));
3828 if (XEXP (SET_SRC (set), 1) == pc_rtx)
3829 code1 = reverse_condition (code1);
3831 b2op0 = XEXP (XEXP (SET_SRC (set2), 0), 0);
3832 b2op1 = XEXP (XEXP (SET_SRC (set2), 0), 1);
3833 code2 = GET_CODE (XEXP (SET_SRC (set2), 0));
3834 if (XEXP (SET_SRC (set2), 1) == pc_rtx)
3835 code2 = reverse_condition (code2);
3837 /* If they test the same things and knowing that B1 branches
3838 tells us whether or not B2 branches, check if we
3839 can thread the branch. */
3840 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
3841 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
3842 && (comparison_dominates_p (code1, code2)
3843 || (can_reverse_comparison_p (XEXP (SET_SRC (set), 0), b1)
3844 && comparison_dominates_p (code1,
3845 reverse_condition (code2)))))
3848 t1 = prev_nonnote_insn (b1);
3849 t2 = prev_nonnote_insn (b2);
3851 while (t1 != 0 && t2 != 0)
3855 /* We have reached the target of the first branch.
3856 If there are no pending register equivalents,
3857 we know that this branch will either always
3858 succeed (if the senses of the two branches are
3859 the same) or always fail (if not). */
3862 if (num_same_regs != 0)
3865 if (comparison_dominates_p (code1, code2))
3866 new_label = JUMP_LABEL (b2);
3868 new_label = get_label_after (b2);
3870 if (JUMP_LABEL (b1) != new_label)
3872 rtx prev = PREV_INSN (new_label);
3874 if (flag_before_loop
3875 && GET_CODE (prev) == NOTE
3876 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
3878 /* Don't thread to the loop label. If a loop
3879 label is reused, loop optimization will
3880 be disabled for that loop. */
3881 new_label = gen_label_rtx ();
3882 emit_label_after (new_label, PREV_INSN (prev));
3884 changed |= redirect_jump (b1, new_label, 1);
3889 /* If either of these is not a normal insn (it might be
3890 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3891 have already been skipped above.) Similarly, fail
3892 if the insns are different. */
3893 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
3894 || recog_memoized (t1) != recog_memoized (t2)
3895 || ! rtx_equal_for_thread_p (PATTERN (t1),
3899 t1 = prev_nonnote_insn (t1);
3900 t2 = prev_nonnote_insn (t2);
3907 free (modified_regs);
3912 /* This is like RTX_EQUAL_P except that it knows about our handling of
3913 possibly equivalent registers and knows to consider volatile and
3914 modified objects as not equal.
3916 YINSN is the insn containing Y. */
3919 rtx_equal_for_thread_p (x, y, yinsn)
3925 register enum rtx_code code;
3926 register const char *fmt;
3928 code = GET_CODE (x);
3929 /* Rtx's of different codes cannot be equal. */
3930 if (code != GET_CODE (y))
3933 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
3934 (REG:SI x) and (REG:HI x) are NOT equivalent. */
3936 if (GET_MODE (x) != GET_MODE (y))
3939 /* For floating-point, consider everything unequal. This is a bit
3940 pessimistic, but this pass would only rarely do anything for FP
3942 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3943 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
3946 /* For commutative operations, the RTX match if the operand match in any
3947 order. Also handle the simple binary and unary cases without a loop. */
3948 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3949 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
3950 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
3951 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
3952 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
3953 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3954 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
3955 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
3956 else if (GET_RTX_CLASS (code) == '1')
3957 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
3959 /* Handle special-cases first. */
3963 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
3966 /* If neither is user variable or hard register, check for possible
3968 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
3969 || REGNO (x) < FIRST_PSEUDO_REGISTER
3970 || REGNO (y) < FIRST_PSEUDO_REGISTER)
3973 if (same_regs[REGNO (x)] == -1)
3975 same_regs[REGNO (x)] = REGNO (y);
3978 /* If this is the first time we are seeing a register on the `Y'
3979 side, see if it is the last use. If not, we can't thread the
3980 jump, so mark it as not equivalent. */
3981 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
3987 return (same_regs[REGNO (x)] == (int) REGNO (y));
3992 /* If memory modified or either volatile, not equivalent.
3993 Else, check address. */
3994 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
3997 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4000 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4006 /* Cancel a pending `same_regs' if setting equivalenced registers.
4007 Then process source. */
4008 if (GET_CODE (SET_DEST (x)) == REG
4009 && GET_CODE (SET_DEST (y)) == REG)
4011 if (same_regs[REGNO (SET_DEST (x))] == (int) REGNO (SET_DEST (y)))
4013 same_regs[REGNO (SET_DEST (x))] = -1;
4016 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4021 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4025 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4028 return XEXP (x, 0) == XEXP (y, 0);
4031 return XSTR (x, 0) == XSTR (y, 0);
4040 fmt = GET_RTX_FORMAT (code);
4041 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4046 if (XWINT (x, i) != XWINT (y, i))
4052 if (XINT (x, i) != XINT (y, i))
4058 /* Two vectors must have the same length. */
4059 if (XVECLEN (x, i) != XVECLEN (y, i))
4062 /* And the corresponding elements must match. */
4063 for (j = 0; j < XVECLEN (x, i); j++)
4064 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4065 XVECEXP (y, i, j), yinsn) == 0)
4070 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4076 if (strcmp (XSTR (x, i), XSTR (y, i)))
4081 /* These are just backpointers, so they don't matter. */
4088 /* It is believed that rtx's at this level will never
4089 contain anything but integers and other rtx's,
4090 except for within LABEL_REFs and SYMBOL_REFs. */