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predict.def: New file.
[gcc.git] / gcc / jump.c
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.
4
5 This file is part of GNU CC.
6
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)
10 any later version.
11
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.
16
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. */
21
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).
25
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.
30
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
37 at by later passes.
38
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'.
43
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
46
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.
50
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
53
54 #include "config.h"
55 #include "system.h"
56 #include "rtl.h"
57 #include "tm_p.h"
58 #include "flags.h"
59 #include "hard-reg-set.h"
60 #include "regs.h"
61 #include "insn-config.h"
62 #include "insn-attr.h"
63 #include "recog.h"
64 #include "function.h"
65 #include "expr.h"
66 #include "real.h"
67 #include "except.h"
68 #include "toplev.h"
69 #include "reload.h"
70 #include "predict.h"
71
72 /* ??? Eventually must record somehow the labels used by jumps
73 from nested functions. */
74 /* Pre-record the next or previous real insn for each label?
75 No, this pass is very fast anyway. */
76 /* Condense consecutive labels?
77 This would make life analysis faster, maybe. */
78 /* Optimize jump y; x: ... y: jumpif... x?
79 Don't know if it is worth bothering with. */
80 /* Optimize two cases of conditional jump to conditional jump?
81 This can never delete any instruction or make anything dead,
82 or even change what is live at any point.
83 So perhaps let combiner do it. */
84
85 /* Vector indexed by uid.
86 For each CODE_LABEL, index by its uid to get first unconditional jump
87 that jumps to the label.
88 For each JUMP_INSN, index by its uid to get the next unconditional jump
89 that jumps to the same label.
90 Element 0 is the start of a chain of all return insns.
91 (It is safe to use element 0 because insn uid 0 is not used. */
92
93 static rtx *jump_chain;
94
95 /* Maximum index in jump_chain. */
96
97 static int max_jump_chain;
98
99 /* Indicates whether death notes are significant in cross jump analysis.
100 Normally they are not significant, because of A and B jump to C,
101 and R dies in A, it must die in B. But this might not be true after
102 stack register conversion, and we must compare death notes in that
103 case. */
104
105 static int cross_jump_death_matters = 0;
106
107 static int init_label_info PARAMS ((rtx));
108 static void delete_barrier_successors PARAMS ((rtx));
109 static void mark_all_labels PARAMS ((rtx, int));
110 static rtx delete_unreferenced_labels PARAMS ((rtx));
111 static void delete_noop_moves PARAMS ((rtx));
112 static int duplicate_loop_exit_test PARAMS ((rtx));
113 static void find_cross_jump PARAMS ((rtx, rtx, int, rtx *, rtx *));
114 static void do_cross_jump PARAMS ((rtx, rtx, rtx));
115 static int jump_back_p PARAMS ((rtx, rtx));
116 static int tension_vector_labels PARAMS ((rtx, int));
117 static void delete_computation PARAMS ((rtx));
118 static void redirect_exp_1 PARAMS ((rtx *, rtx, rtx, rtx));
119 static int redirect_exp PARAMS ((rtx, rtx, rtx));
120 static void invert_exp_1 PARAMS ((rtx));
121 static int invert_exp PARAMS ((rtx));
122 static void delete_from_jump_chain PARAMS ((rtx));
123 static int delete_labelref_insn PARAMS ((rtx, rtx, int));
124 static void mark_modified_reg PARAMS ((rtx, rtx, void *));
125 static void redirect_tablejump PARAMS ((rtx, rtx));
126 static void jump_optimize_1 PARAMS ((rtx, int, int, int, int, int));
127 static int returnjump_p_1 PARAMS ((rtx *, void *));
128 static void delete_prior_computation PARAMS ((rtx, rtx));
129 \f
130 /* Main external entry point into the jump optimizer. See comments before
131 jump_optimize_1 for descriptions of the arguments. */
132 void
133 jump_optimize (f, cross_jump, noop_moves, after_regscan)
134 rtx f;
135 int cross_jump;
136 int noop_moves;
137 int after_regscan;
138 {
139 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0, 0);
140 }
141
142 /* Alternate entry into the jump optimizer. This entry point only rebuilds
143 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
144 instructions. */
145 void
146 rebuild_jump_labels (f)
147 rtx f;
148 {
149 jump_optimize_1 (f, 0, 0, 0, 1, 0);
150 }
151
152 /* Alternate entry into the jump optimizer. Do only trivial optimizations. */
153
154 void
155 jump_optimize_minimal (f)
156 rtx f;
157 {
158 jump_optimize_1 (f, 0, 0, 0, 0, 1);
159 }
160 \f
161 /* Delete no-op jumps and optimize jumps to jumps
162 and jumps around jumps.
163 Delete unused labels and unreachable code.
164
165 If CROSS_JUMP is 1, detect matching code
166 before a jump and its destination and unify them.
167 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
168
169 If NOOP_MOVES is nonzero, delete no-op move insns.
170
171 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
172 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
173
174 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
175 and JUMP_LABEL field for jumping insns.
176
177 If `optimize' is zero, don't change any code,
178 just determine whether control drops off the end of the function.
179 This case occurs when we have -W and not -O.
180 It works because `delete_insn' checks the value of `optimize'
181 and refrains from actually deleting when that is 0.
182
183 If MINIMAL is nonzero, then we only perform trivial optimizations:
184
185 * Removal of unreachable code after BARRIERs.
186 * Removal of unreferenced CODE_LABELs.
187 * Removal of a jump to the next instruction.
188 * Removal of a conditional jump followed by an unconditional jump
189 to the same target as the conditional jump.
190 * Simplify a conditional jump around an unconditional jump.
191 * Simplify a jump to a jump.
192 * Delete extraneous line number notes.
193 */
194
195 static void
196 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan,
197 mark_labels_only, minimal)
198 rtx f;
199 int cross_jump;
200 int noop_moves;
201 int after_regscan;
202 int mark_labels_only;
203 int minimal;
204 {
205 register rtx insn, next;
206 int changed;
207 int old_max_reg;
208 int first = 1;
209 int max_uid = 0;
210 rtx last_insn;
211 #ifdef HAVE_trap
212 enum rtx_code reversed_code;
213 #endif
214
215 cross_jump_death_matters = (cross_jump == 2);
216 max_uid = init_label_info (f) + 1;
217
218 /* Leave some extra room for labels and duplicate exit test insns
219 we make. */
220 max_jump_chain = max_uid * 14 / 10;
221 jump_chain = (rtx *) xcalloc (max_jump_chain, sizeof (rtx));
222
223 mark_all_labels (f, cross_jump);
224
225 /* Keep track of labels used from static data; we don't track them
226 closely enough to delete them here, so make sure their reference
227 count doesn't drop to zero. */
228
229 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
230 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
231 LABEL_NUSES (XEXP (insn, 0))++;
232
233 /* Keep track of labels used for marking handlers for exception
234 regions; they cannot usually be deleted. */
235
236 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
237 if (GET_CODE (XEXP (insn, 0)) == CODE_LABEL)
238 LABEL_NUSES (XEXP (insn, 0))++;
239
240 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
241 notes and recompute LABEL_NUSES. */
242 if (mark_labels_only)
243 goto end;
244
245 delete_barrier_successors (f);
246
247 last_insn = delete_unreferenced_labels (f);
248
249 if (noop_moves)
250 delete_noop_moves (f);
251
252 /* Now iterate optimizing jumps until nothing changes over one pass. */
253 changed = 1;
254 old_max_reg = max_reg_num ();
255 while (changed)
256 {
257 changed = 0;
258
259 for (insn = f; insn; insn = next)
260 {
261 rtx reallabelprev;
262 rtx temp, temp1, temp2 = NULL_RTX;
263 rtx temp4 ATTRIBUTE_UNUSED;
264 rtx nlabel;
265 int this_is_any_uncondjump;
266 int this_is_any_condjump;
267 int this_is_onlyjump;
268
269 next = NEXT_INSN (insn);
270
271 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
272 jump. Try to optimize by duplicating the loop exit test if so.
273 This is only safe immediately after regscan, because it uses
274 the values of regno_first_uid and regno_last_uid. */
275 if (after_regscan && GET_CODE (insn) == NOTE
276 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
277 && (temp1 = next_nonnote_insn (insn)) != 0
278 && any_uncondjump_p (temp1)
279 && onlyjump_p (temp1))
280 {
281 temp = PREV_INSN (insn);
282 if (duplicate_loop_exit_test (insn))
283 {
284 changed = 1;
285 next = NEXT_INSN (temp);
286 continue;
287 }
288 }
289
290 if (GET_CODE (insn) != JUMP_INSN)
291 continue;
292
293 this_is_any_condjump = any_condjump_p (insn);
294 this_is_any_uncondjump = any_uncondjump_p (insn);
295 this_is_onlyjump = onlyjump_p (insn);
296
297 /* Tension the labels in dispatch tables. */
298
299 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
300 changed |= tension_vector_labels (PATTERN (insn), 0);
301 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
302 changed |= tension_vector_labels (PATTERN (insn), 1);
303
304 /* See if this jump goes to another jump and redirect if so. */
305 nlabel = follow_jumps (JUMP_LABEL (insn));
306 if (nlabel != JUMP_LABEL (insn))
307 changed |= redirect_jump (insn, nlabel, 1);
308
309 if (! optimize || minimal)
310 continue;
311
312 /* If a dispatch table always goes to the same place,
313 get rid of it and replace the insn that uses it. */
314
315 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
316 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
317 {
318 int i;
319 rtx pat = PATTERN (insn);
320 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
321 int len = XVECLEN (pat, diff_vec_p);
322 rtx dispatch = prev_real_insn (insn);
323 rtx set;
324
325 for (i = 0; i < len; i++)
326 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
327 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
328 break;
329
330 if (i == len
331 && dispatch != 0
332 && GET_CODE (dispatch) == JUMP_INSN
333 && JUMP_LABEL (dispatch) != 0
334 /* Don't mess with a casesi insn.
335 XXX according to the comment before computed_jump_p(),
336 all casesi insns should be a parallel of the jump
337 and a USE of a LABEL_REF. */
338 && ! ((set = single_set (dispatch)) != NULL
339 && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE))
340 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
341 {
342 redirect_tablejump (dispatch,
343 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
344 changed = 1;
345 }
346 }
347
348 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
349
350 /* Detect jump to following insn. */
351 if (reallabelprev == insn
352 && (this_is_any_condjump || this_is_any_uncondjump)
353 && this_is_onlyjump)
354 {
355 next = next_real_insn (JUMP_LABEL (insn));
356 delete_jump (insn);
357
358 /* Remove the "inactive" but "real" insns (i.e. uses and
359 clobbers) in between here and there. */
360 temp = insn;
361 while ((temp = next_real_insn (temp)) != next)
362 delete_insn (temp);
363
364 changed = 1;
365 continue;
366 }
367
368 /* Detect a conditional jump going to the same place
369 as an immediately following unconditional jump. */
370 else if (this_is_any_condjump && this_is_onlyjump
371 && (temp = next_active_insn (insn)) != 0
372 && simplejump_p (temp)
373 && (next_active_insn (JUMP_LABEL (insn))
374 == next_active_insn (JUMP_LABEL (temp))))
375 {
376 /* Don't mess up test coverage analysis. */
377 temp2 = temp;
378 if (flag_test_coverage && !reload_completed)
379 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
380 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
381 break;
382
383 if (temp2 == temp)
384 {
385 /* Ensure that we jump to the later of the two labels.
386 Consider:
387
388 if (test) goto L2;
389 goto L1;
390 ...
391 L1:
392 (clobber return-reg)
393 L2:
394 (use return-reg)
395
396 If we leave the goto L1, we'll incorrectly leave
397 return-reg dead for TEST true. */
398
399 temp2 = next_active_insn (JUMP_LABEL (insn));
400 if (!temp2)
401 temp2 = get_last_insn ();
402 if (GET_CODE (temp2) != CODE_LABEL)
403 temp2 = prev_label (temp2);
404 if (temp2 != JUMP_LABEL (temp))
405 redirect_jump (temp, temp2, 1);
406
407 delete_jump (insn);
408 changed = 1;
409 continue;
410 }
411 }
412
413 /* Detect a conditional jump jumping over an unconditional jump. */
414
415 else if (this_is_any_condjump
416 && reallabelprev != 0
417 && GET_CODE (reallabelprev) == JUMP_INSN
418 && prev_active_insn (reallabelprev) == insn
419 && no_labels_between_p (insn, reallabelprev)
420 && any_uncondjump_p (reallabelprev)
421 && onlyjump_p (reallabelprev))
422 {
423 /* When we invert the unconditional jump, we will be
424 decrementing the usage count of its old label.
425 Make sure that we don't delete it now because that
426 might cause the following code to be deleted. */
427 rtx prev_uses = prev_nonnote_insn (reallabelprev);
428 rtx prev_label = JUMP_LABEL (insn);
429
430 if (prev_label)
431 ++LABEL_NUSES (prev_label);
432
433 if (invert_jump (insn, JUMP_LABEL (reallabelprev), 1))
434 {
435 /* It is very likely that if there are USE insns before
436 this jump, they hold REG_DEAD notes. These REG_DEAD
437 notes are no longer valid due to this optimization,
438 and will cause the life-analysis that following passes
439 (notably delayed-branch scheduling) to think that
440 these registers are dead when they are not.
441
442 To prevent this trouble, we just remove the USE insns
443 from the insn chain. */
444
445 while (prev_uses && GET_CODE (prev_uses) == INSN
446 && GET_CODE (PATTERN (prev_uses)) == USE)
447 {
448 rtx useless = prev_uses;
449 prev_uses = prev_nonnote_insn (prev_uses);
450 delete_insn (useless);
451 }
452
453 delete_insn (reallabelprev);
454 changed = 1;
455 }
456
457 /* We can now safely delete the label if it is unreferenced
458 since the delete_insn above has deleted the BARRIER. */
459 if (prev_label && --LABEL_NUSES (prev_label) == 0)
460 delete_insn (prev_label);
461
462 next = NEXT_INSN (insn);
463 }
464
465 /* If we have an unconditional jump preceded by a USE, try to put
466 the USE before the target and jump there. This simplifies many
467 of the optimizations below since we don't have to worry about
468 dealing with these USE insns. We only do this if the label
469 being branch to already has the identical USE or if code
470 never falls through to that label. */
471
472 else if (this_is_any_uncondjump
473 && (temp = prev_nonnote_insn (insn)) != 0
474 && GET_CODE (temp) == INSN
475 && GET_CODE (PATTERN (temp)) == USE
476 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
477 && (GET_CODE (temp1) == BARRIER
478 || (GET_CODE (temp1) == INSN
479 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
480 /* Don't do this optimization if we have a loop containing
481 only the USE instruction, and the loop start label has
482 a usage count of 1. This is because we will redo this
483 optimization everytime through the outer loop, and jump
484 opt will never exit. */
485 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
486 && temp2 == JUMP_LABEL (insn)
487 && LABEL_NUSES (temp2) == 1))
488 {
489 if (GET_CODE (temp1) == BARRIER)
490 {
491 emit_insn_after (PATTERN (temp), temp1);
492 temp1 = NEXT_INSN (temp1);
493 }
494
495 delete_insn (temp);
496 redirect_jump (insn, get_label_before (temp1), 1);
497 reallabelprev = prev_real_insn (temp1);
498 changed = 1;
499 next = NEXT_INSN (insn);
500 }
501
502 #ifdef HAVE_trap
503 /* Detect a conditional jump jumping over an unconditional trap. */
504 if (HAVE_trap
505 && this_is_any_condjump && this_is_onlyjump
506 && reallabelprev != 0
507 && GET_CODE (reallabelprev) == INSN
508 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
509 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
510 && prev_active_insn (reallabelprev) == insn
511 && no_labels_between_p (insn, reallabelprev)
512 && (temp2 = get_condition (insn, &temp4))
513 && ((reversed_code = reversed_comparison_code (temp2, insn))
514 != UNKNOWN))
515 {
516 rtx new = gen_cond_trap (reversed_code,
517 XEXP (temp2, 0), XEXP (temp2, 1),
518 TRAP_CODE (PATTERN (reallabelprev)));
519
520 if (new)
521 {
522 emit_insn_before (new, temp4);
523 delete_insn (reallabelprev);
524 delete_jump (insn);
525 changed = 1;
526 continue;
527 }
528 }
529 /* Detect a jump jumping to an unconditional trap. */
530 else if (HAVE_trap && this_is_onlyjump
531 && (temp = next_active_insn (JUMP_LABEL (insn)))
532 && GET_CODE (temp) == INSN
533 && GET_CODE (PATTERN (temp)) == TRAP_IF
534 && (this_is_any_uncondjump
535 || (this_is_any_condjump
536 && (temp2 = get_condition (insn, &temp4)))))
537 {
538 rtx tc = TRAP_CONDITION (PATTERN (temp));
539
540 if (tc == const_true_rtx
541 || (! this_is_any_uncondjump && rtx_equal_p (temp2, tc)))
542 {
543 rtx new;
544 /* Replace an unconditional jump to a trap with a trap. */
545 if (this_is_any_uncondjump)
546 {
547 emit_barrier_after (emit_insn_before (gen_trap (), insn));
548 delete_jump (insn);
549 changed = 1;
550 continue;
551 }
552 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
553 XEXP (temp2, 1),
554 TRAP_CODE (PATTERN (temp)));
555 if (new)
556 {
557 emit_insn_before (new, temp4);
558 delete_jump (insn);
559 changed = 1;
560 continue;
561 }
562 }
563 /* If the trap condition and jump condition are mutually
564 exclusive, redirect the jump to the following insn. */
565 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
566 && this_is_any_condjump
567 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
568 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
569 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
570 && redirect_jump (insn, get_label_after (temp), 1))
571 {
572 changed = 1;
573 continue;
574 }
575 }
576 #endif
577 else
578 {
579 /* Now that the jump has been tensioned,
580 try cross jumping: check for identical code
581 before the jump and before its target label. */
582
583 /* First, cross jumping of conditional jumps: */
584
585 if (cross_jump && condjump_p (insn))
586 {
587 rtx newjpos, newlpos;
588 rtx x = prev_real_insn (JUMP_LABEL (insn));
589
590 /* A conditional jump may be crossjumped
591 only if the place it jumps to follows
592 an opposing jump that comes back here. */
593
594 if (x != 0 && ! jump_back_p (x, insn))
595 /* We have no opposing jump;
596 cannot cross jump this insn. */
597 x = 0;
598
599 newjpos = 0;
600 /* TARGET is nonzero if it is ok to cross jump
601 to code before TARGET. If so, see if matches. */
602 if (x != 0)
603 find_cross_jump (insn, x, 2,
604 &newjpos, &newlpos);
605
606 if (newjpos != 0)
607 {
608 do_cross_jump (insn, newjpos, newlpos);
609 /* Make the old conditional jump
610 into an unconditional one. */
611 PATTERN (insn) = gen_jump (JUMP_LABEL (insn));
612 INSN_CODE (insn) = -1;
613 emit_barrier_after (insn);
614 /* Add to jump_chain unless this is a new label
615 whose UID is too large. */
616 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
617 {
618 jump_chain[INSN_UID (insn)]
619 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
620 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
621 }
622 changed = 1;
623 next = insn;
624 }
625 }
626
627 /* Cross jumping of unconditional jumps:
628 a few differences. */
629
630 if (cross_jump && simplejump_p (insn))
631 {
632 rtx newjpos, newlpos;
633 rtx target;
634
635 newjpos = 0;
636
637 /* TARGET is nonzero if it is ok to cross jump
638 to code before TARGET. If so, see if matches. */
639 find_cross_jump (insn, JUMP_LABEL (insn), 1,
640 &newjpos, &newlpos);
641
642 /* If cannot cross jump to code before the label,
643 see if we can cross jump to another jump to
644 the same label. */
645 /* Try each other jump to this label. */
646 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
647 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
648 target != 0 && newjpos == 0;
649 target = jump_chain[INSN_UID (target)])
650 if (target != insn
651 && JUMP_LABEL (target) == JUMP_LABEL (insn)
652 /* Ignore TARGET if it's deleted. */
653 && ! INSN_DELETED_P (target))
654 find_cross_jump (insn, target, 2,
655 &newjpos, &newlpos);
656
657 if (newjpos != 0)
658 {
659 do_cross_jump (insn, newjpos, newlpos);
660 changed = 1;
661 next = insn;
662 }
663 }
664
665 /* This code was dead in the previous jump.c! */
666 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
667 {
668 /* Return insns all "jump to the same place"
669 so we can cross-jump between any two of them. */
670
671 rtx newjpos, newlpos, target;
672
673 newjpos = 0;
674
675 /* If cannot cross jump to code before the label,
676 see if we can cross jump to another jump to
677 the same label. */
678 /* Try each other jump to this label. */
679 for (target = jump_chain[0];
680 target != 0 && newjpos == 0;
681 target = jump_chain[INSN_UID (target)])
682 if (target != insn
683 && ! INSN_DELETED_P (target)
684 && GET_CODE (PATTERN (target)) == RETURN)
685 find_cross_jump (insn, target, 2,
686 &newjpos, &newlpos);
687
688 if (newjpos != 0)
689 {
690 do_cross_jump (insn, newjpos, newlpos);
691 changed = 1;
692 next = insn;
693 }
694 }
695 }
696 }
697
698 first = 0;
699 }
700
701 /* Delete extraneous line number notes.
702 Note that two consecutive notes for different lines are not really
703 extraneous. There should be some indication where that line belonged,
704 even if it became empty. */
705
706 {
707 rtx last_note = 0;
708
709 for (insn = f; insn; insn = NEXT_INSN (insn))
710 if (GET_CODE (insn) == NOTE)
711 {
712 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
713 /* Any previous line note was for the prologue; gdb wants a new
714 note after the prologue even if it is for the same line. */
715 last_note = NULL_RTX;
716 else if (NOTE_LINE_NUMBER (insn) >= 0)
717 {
718 /* Delete this note if it is identical to previous note. */
719 if (last_note
720 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
721 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
722 {
723 delete_insn (insn);
724 continue;
725 }
726
727 last_note = insn;
728 }
729 }
730 }
731
732 end:
733 /* Clean up. */
734 free (jump_chain);
735 jump_chain = 0;
736 }
737 \f
738 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
739 notes whose labels don't occur in the insn any more. Returns the
740 largest INSN_UID found. */
741 static int
742 init_label_info (f)
743 rtx f;
744 {
745 int largest_uid = 0;
746 rtx insn;
747
748 for (insn = f; insn; insn = NEXT_INSN (insn))
749 {
750 if (GET_CODE (insn) == CODE_LABEL)
751 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
752 else if (GET_CODE (insn) == JUMP_INSN)
753 JUMP_LABEL (insn) = 0;
754 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
755 {
756 rtx note, next;
757
758 for (note = REG_NOTES (insn); note; note = next)
759 {
760 next = XEXP (note, 1);
761 if (REG_NOTE_KIND (note) == REG_LABEL
762 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
763 remove_note (insn, note);
764 }
765 }
766 if (INSN_UID (insn) > largest_uid)
767 largest_uid = INSN_UID (insn);
768 }
769
770 return largest_uid;
771 }
772
773 /* Delete insns following barriers, up to next label.
774
775 Also delete no-op jumps created by gcse. */
776
777 static void
778 delete_barrier_successors (f)
779 rtx f;
780 {
781 rtx insn;
782 rtx set;
783
784 for (insn = f; insn;)
785 {
786 if (GET_CODE (insn) == BARRIER)
787 {
788 insn = NEXT_INSN (insn);
789
790 never_reached_warning (insn);
791
792 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
793 {
794 if (GET_CODE (insn) == JUMP_INSN)
795 {
796 /* Detect when we're deleting a tablejump; get rid of
797 the jump table as well. */
798 rtx next1 = next_nonnote_insn (insn);
799 rtx next2 = next1 ? next_nonnote_insn (next1) : 0;
800 if (next2 && GET_CODE (next1) == CODE_LABEL
801 && GET_CODE (next2) == JUMP_INSN
802 && (GET_CODE (PATTERN (next2)) == ADDR_VEC
803 || GET_CODE (PATTERN (next2)) == ADDR_DIFF_VEC))
804 {
805 delete_insn (insn);
806 insn = next2;
807 }
808 else
809 insn = delete_insn (insn);
810 }
811 else if (GET_CODE (insn) == NOTE
812 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
813 insn = NEXT_INSN (insn);
814 else
815 insn = delete_insn (insn);
816 }
817 /* INSN is now the code_label. */
818 }
819
820 /* Also remove (set (pc) (pc)) insns which can be created by
821 gcse. We eliminate such insns now to avoid having them
822 cause problems later. */
823 else if (GET_CODE (insn) == JUMP_INSN
824 && (set = pc_set (insn)) != NULL
825 && SET_SRC (set) == pc_rtx
826 && SET_DEST (set) == pc_rtx
827 && onlyjump_p (insn))
828 insn = delete_insn (insn);
829
830 else
831 insn = NEXT_INSN (insn);
832 }
833 }
834
835 /* Mark the label each jump jumps to.
836 Combine consecutive labels, and count uses of labels.
837
838 For each label, make a chain (using `jump_chain')
839 of all the *unconditional* jumps that jump to it;
840 also make a chain of all returns.
841
842 CROSS_JUMP indicates whether we are doing cross jumping
843 and if we are whether we will be paying attention to
844 death notes or not. */
845
846 static void
847 mark_all_labels (f, cross_jump)
848 rtx f;
849 int cross_jump;
850 {
851 rtx insn;
852
853 for (insn = f; insn; insn = NEXT_INSN (insn))
854 if (INSN_P (insn))
855 {
856 if (GET_CODE (insn) == CALL_INSN
857 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
858 {
859 mark_all_labels (XEXP (PATTERN (insn), 0), cross_jump);
860 mark_all_labels (XEXP (PATTERN (insn), 1), cross_jump);
861 mark_all_labels (XEXP (PATTERN (insn), 2), cross_jump);
862
863 /* Canonicalize the tail recursion label attached to the
864 CALL_PLACEHOLDER insn. */
865 if (XEXP (PATTERN (insn), 3))
866 {
867 rtx label_ref = gen_rtx_LABEL_REF (VOIDmode,
868 XEXP (PATTERN (insn), 3));
869 mark_jump_label (label_ref, insn, cross_jump, 0);
870 XEXP (PATTERN (insn), 3) = XEXP (label_ref, 0);
871 }
872
873 continue;
874 }
875
876 mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
877 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
878 {
879 /* When we know the LABEL_REF contained in a REG used in
880 an indirect jump, we'll have a REG_LABEL note so that
881 flow can tell where it's going. */
882 if (JUMP_LABEL (insn) == 0)
883 {
884 rtx label_note = find_reg_note (insn, REG_LABEL, NULL_RTX);
885 if (label_note)
886 {
887 /* But a LABEL_REF around the REG_LABEL note, so
888 that we can canonicalize it. */
889 rtx label_ref = gen_rtx_LABEL_REF (VOIDmode,
890 XEXP (label_note, 0));
891
892 mark_jump_label (label_ref, insn, cross_jump, 0);
893 XEXP (label_note, 0) = XEXP (label_ref, 0);
894 JUMP_LABEL (insn) = XEXP (label_note, 0);
895 }
896 }
897 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
898 {
899 jump_chain[INSN_UID (insn)]
900 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
901 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
902 }
903 if (GET_CODE (PATTERN (insn)) == RETURN)
904 {
905 jump_chain[INSN_UID (insn)] = jump_chain[0];
906 jump_chain[0] = insn;
907 }
908 }
909 }
910 }
911
912 /* Delete all labels already not referenced.
913 Also find and return the last insn. */
914
915 static rtx
916 delete_unreferenced_labels (f)
917 rtx f;
918 {
919 rtx final = NULL_RTX;
920 rtx insn;
921
922 for (insn = f; insn;)
923 {
924 if (GET_CODE (insn) == CODE_LABEL
925 && LABEL_NUSES (insn) == 0
926 && LABEL_ALTERNATE_NAME (insn) == NULL)
927 insn = delete_insn (insn);
928 else
929 {
930 final = insn;
931 insn = NEXT_INSN (insn);
932 }
933 }
934
935 return final;
936 }
937
938 /* Delete various simple forms of moves which have no necessary
939 side effect. */
940
941 static void
942 delete_noop_moves (f)
943 rtx f;
944 {
945 rtx insn, next;
946
947 for (insn = f; insn;)
948 {
949 next = NEXT_INSN (insn);
950
951 if (GET_CODE (insn) == INSN)
952 {
953 register rtx body = PATTERN (insn);
954
955 /* Detect and delete no-op move instructions
956 resulting from not allocating a parameter in a register. */
957
958 if (GET_CODE (body) == SET && set_noop_p (body))
959 delete_computation (insn);
960
961 /* Detect and ignore no-op move instructions
962 resulting from smart or fortuitous register allocation. */
963
964 else if (GET_CODE (body) == SET)
965 {
966 int sreg = true_regnum (SET_SRC (body));
967 int dreg = true_regnum (SET_DEST (body));
968
969 if (sreg == dreg && sreg >= 0)
970 delete_insn (insn);
971 else if (sreg >= 0 && dreg >= 0)
972 {
973 rtx trial;
974 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
975 sreg, NULL, dreg,
976 GET_MODE (SET_SRC (body)));
977
978 if (tem != 0
979 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
980 {
981 /* DREG may have been the target of a REG_DEAD note in
982 the insn which makes INSN redundant. If so, reorg
983 would still think it is dead. So search for such a
984 note and delete it if we find it. */
985 if (! find_regno_note (insn, REG_UNUSED, dreg))
986 for (trial = prev_nonnote_insn (insn);
987 trial && GET_CODE (trial) != CODE_LABEL;
988 trial = prev_nonnote_insn (trial))
989 if (find_regno_note (trial, REG_DEAD, dreg))
990 {
991 remove_death (dreg, trial);
992 break;
993 }
994
995 /* Deleting insn could lose a death-note for SREG. */
996 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
997 {
998 /* Change this into a USE so that we won't emit
999 code for it, but still can keep the note. */
1000 PATTERN (insn)
1001 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
1002 INSN_CODE (insn) = -1;
1003 /* Remove all reg notes but the REG_DEAD one. */
1004 REG_NOTES (insn) = trial;
1005 XEXP (trial, 1) = NULL_RTX;
1006 }
1007 else
1008 delete_insn (insn);
1009 }
1010 }
1011 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
1012 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
1013 NULL, 0, GET_MODE (SET_DEST (body))))
1014 {
1015 /* This handles the case where we have two consecutive
1016 assignments of the same constant to pseudos that didn't
1017 get a hard reg. Each SET from the constant will be
1018 converted into a SET of the spill register and an
1019 output reload will be made following it. This produces
1020 two loads of the same constant into the same spill
1021 register. */
1022
1023 rtx in_insn = insn;
1024
1025 /* Look back for a death note for the first reg.
1026 If there is one, it is no longer accurate. */
1027 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
1028 {
1029 if ((GET_CODE (in_insn) == INSN
1030 || GET_CODE (in_insn) == JUMP_INSN)
1031 && find_regno_note (in_insn, REG_DEAD, dreg))
1032 {
1033 remove_death (dreg, in_insn);
1034 break;
1035 }
1036 in_insn = PREV_INSN (in_insn);
1037 }
1038
1039 /* Delete the second load of the value. */
1040 delete_insn (insn);
1041 }
1042 }
1043 else if (GET_CODE (body) == PARALLEL)
1044 {
1045 /* If each part is a set between two identical registers or
1046 a USE or CLOBBER, delete the insn. */
1047 int i, sreg, dreg;
1048 rtx tem;
1049
1050 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
1051 {
1052 tem = XVECEXP (body, 0, i);
1053 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
1054 continue;
1055
1056 if (GET_CODE (tem) != SET
1057 || (sreg = true_regnum (SET_SRC (tem))) < 0
1058 || (dreg = true_regnum (SET_DEST (tem))) < 0
1059 || dreg != sreg)
1060 break;
1061 }
1062
1063 if (i < 0)
1064 delete_insn (insn);
1065 }
1066 }
1067 insn = next;
1068 }
1069 }
1070
1071 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1072 jump. Assume that this unconditional jump is to the exit test code. If
1073 the code is sufficiently simple, make a copy of it before INSN,
1074 followed by a jump to the exit of the loop. Then delete the unconditional
1075 jump after INSN.
1076
1077 Return 1 if we made the change, else 0.
1078
1079 This is only safe immediately after a regscan pass because it uses the
1080 values of regno_first_uid and regno_last_uid. */
1081
1082 static int
1083 duplicate_loop_exit_test (loop_start)
1084 rtx loop_start;
1085 {
1086 rtx insn, set, reg, p, link;
1087 rtx copy = 0, first_copy = 0;
1088 int num_insns = 0;
1089 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
1090 rtx lastexit;
1091 int max_reg = max_reg_num ();
1092 rtx *reg_map = 0;
1093
1094 /* Scan the exit code. We do not perform this optimization if any insn:
1095
1096 is a CALL_INSN
1097 is a CODE_LABEL
1098 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1099 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1100 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1101 is not valid.
1102
1103 We also do not do this if we find an insn with ASM_OPERANDS. While
1104 this restriction should not be necessary, copying an insn with
1105 ASM_OPERANDS can confuse asm_noperands in some cases.
1106
1107 Also, don't do this if the exit code is more than 20 insns. */
1108
1109 for (insn = exitcode;
1110 insn
1111 && ! (GET_CODE (insn) == NOTE
1112 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
1113 insn = NEXT_INSN (insn))
1114 {
1115 switch (GET_CODE (insn))
1116 {
1117 case CODE_LABEL:
1118 case CALL_INSN:
1119 return 0;
1120 case NOTE:
1121 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
1122 a jump immediately after the loop start that branches outside
1123 the loop but within an outer loop, near the exit test.
1124 If we copied this exit test and created a phony
1125 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
1126 before the exit test look like these could be safely moved
1127 out of the loop even if they actually may be never executed.
1128 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
1129
1130 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1131 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
1132 return 0;
1133
1134 if (optimize < 2
1135 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1136 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
1137 /* If we were to duplicate this code, we would not move
1138 the BLOCK notes, and so debugging the moved code would
1139 be difficult. Thus, we only move the code with -O2 or
1140 higher. */
1141 return 0;
1142
1143 break;
1144 case JUMP_INSN:
1145 case INSN:
1146 /* The code below would grossly mishandle REG_WAS_0 notes,
1147 so get rid of them here. */
1148 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
1149 remove_note (insn, p);
1150 if (++num_insns > 20
1151 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1152 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
1153 return 0;
1154 break;
1155 default:
1156 break;
1157 }
1158 }
1159
1160 /* Unless INSN is zero, we can do the optimization. */
1161 if (insn == 0)
1162 return 0;
1163
1164 lastexit = insn;
1165
1166 /* See if any insn sets a register only used in the loop exit code and
1167 not a user variable. If so, replace it with a new register. */
1168 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1169 if (GET_CODE (insn) == INSN
1170 && (set = single_set (insn)) != 0
1171 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
1172 || (GET_CODE (reg) == SUBREG
1173 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
1174 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
1175 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
1176 {
1177 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
1178 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
1179 break;
1180
1181 if (p != lastexit)
1182 {
1183 /* We can do the replacement. Allocate reg_map if this is the
1184 first replacement we found. */
1185 if (reg_map == 0)
1186 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
1187
1188 REG_LOOP_TEST_P (reg) = 1;
1189
1190 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
1191 }
1192 }
1193
1194 /* Now copy each insn. */
1195 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1196 {
1197 switch (GET_CODE (insn))
1198 {
1199 case BARRIER:
1200 copy = emit_barrier_before (loop_start);
1201 break;
1202 case NOTE:
1203 /* Only copy line-number notes. */
1204 if (NOTE_LINE_NUMBER (insn) >= 0)
1205 {
1206 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
1207 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
1208 }
1209 break;
1210
1211 case INSN:
1212 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
1213 if (reg_map)
1214 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1215
1216 mark_jump_label (PATTERN (copy), copy, 0, 0);
1217
1218 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1219 make them. */
1220 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1221 if (REG_NOTE_KIND (link) != REG_LABEL)
1222 {
1223 if (GET_CODE (link) == EXPR_LIST)
1224 REG_NOTES (copy)
1225 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
1226 XEXP (link, 0),
1227 REG_NOTES (copy)));
1228 else
1229 REG_NOTES (copy)
1230 = copy_insn_1 (gen_rtx_INSN_LIST (REG_NOTE_KIND (link),
1231 XEXP (link, 0),
1232 REG_NOTES (copy)));
1233 }
1234
1235 if (reg_map && REG_NOTES (copy))
1236 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1237 break;
1238
1239 case JUMP_INSN:
1240 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)),
1241 loop_start);
1242 if (reg_map)
1243 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1244 mark_jump_label (PATTERN (copy), copy, 0, 0);
1245 if (REG_NOTES (insn))
1246 {
1247 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
1248 if (reg_map)
1249 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1250 }
1251
1252 /* Predict conditional jump that do make loop looping as taken.
1253 Other jumps are probably exit conditions, so predict
1254 them as untaken. */
1255 if (any_condjump_p (copy))
1256 {
1257 rtx label = JUMP_LABEL (copy);
1258 if (label)
1259 {
1260 if (PREV_INSN (label)
1261 && GET_CODE (PREV_INSN (label)) == NOTE
1262 && (NOTE_LINE_NUMBER (PREV_INSN (label))
1263 == NOTE_INSN_LOOP_CONT))
1264 predict_insn_def (copy, PRED_LOOP_HEADER, TAKEN);
1265 else
1266 predict_insn_def (copy, PRED_LOOP_HEADER, NOT_TAKEN);
1267 }
1268 }
1269 /* If this is a simple jump, add it to the jump chain. */
1270
1271 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
1272 && simplejump_p (copy))
1273 {
1274 jump_chain[INSN_UID (copy)]
1275 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1276 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1277 }
1278 break;
1279
1280 default:
1281 abort ();
1282 }
1283
1284 /* Record the first insn we copied. We need it so that we can
1285 scan the copied insns for new pseudo registers. */
1286 if (! first_copy)
1287 first_copy = copy;
1288 }
1289
1290 /* Now clean up by emitting a jump to the end label and deleting the jump
1291 at the start of the loop. */
1292 if (! copy || GET_CODE (copy) != BARRIER)
1293 {
1294 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
1295 loop_start);
1296
1297 /* Record the first insn we copied. We need it so that we can
1298 scan the copied insns for new pseudo registers. This may not
1299 be strictly necessary since we should have copied at least one
1300 insn above. But I am going to be safe. */
1301 if (! first_copy)
1302 first_copy = copy;
1303
1304 mark_jump_label (PATTERN (copy), copy, 0, 0);
1305 if (INSN_UID (copy) < max_jump_chain
1306 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
1307 {
1308 jump_chain[INSN_UID (copy)]
1309 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1310 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1311 }
1312 emit_barrier_before (loop_start);
1313 }
1314
1315 /* Now scan from the first insn we copied to the last insn we copied
1316 (copy) for new pseudo registers. Do this after the code to jump to
1317 the end label since that might create a new pseudo too. */
1318 reg_scan_update (first_copy, copy, max_reg);
1319
1320 /* Mark the exit code as the virtual top of the converted loop. */
1321 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
1322
1323 delete_insn (next_nonnote_insn (loop_start));
1324
1325 /* Clean up. */
1326 if (reg_map)
1327 free (reg_map);
1328
1329 return 1;
1330 }
1331 \f
1332 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
1333 notes between START and END out before START. Assume that END is not
1334 such a note. START may be such a note. Returns the value of the new
1335 starting insn, which may be different if the original start was such a
1336 note. */
1337
1338 rtx
1339 squeeze_notes (start, end)
1340 rtx start, end;
1341 {
1342 rtx insn;
1343 rtx next;
1344
1345 for (insn = start; insn != end; insn = next)
1346 {
1347 next = NEXT_INSN (insn);
1348 if (GET_CODE (insn) == NOTE
1349 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
1350 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1351 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1352 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
1353 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
1354 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
1355 {
1356 if (insn == start)
1357 start = next;
1358 else
1359 {
1360 rtx prev = PREV_INSN (insn);
1361 PREV_INSN (insn) = PREV_INSN (start);
1362 NEXT_INSN (insn) = start;
1363 NEXT_INSN (PREV_INSN (insn)) = insn;
1364 PREV_INSN (NEXT_INSN (insn)) = insn;
1365 NEXT_INSN (prev) = next;
1366 PREV_INSN (next) = prev;
1367 }
1368 }
1369 }
1370
1371 return start;
1372 }
1373 \f
1374 /* Compare the instructions before insn E1 with those before E2
1375 to find an opportunity for cross jumping.
1376 (This means detecting identical sequences of insns followed by
1377 jumps to the same place, or followed by a label and a jump
1378 to that label, and replacing one with a jump to the other.)
1379
1380 Assume E1 is a jump that jumps to label E2
1381 (that is not always true but it might as well be).
1382 Find the longest possible equivalent sequences
1383 and store the first insns of those sequences into *F1 and *F2.
1384 Store zero there if no equivalent preceding instructions are found.
1385
1386 We give up if we find a label in stream 1.
1387 Actually we could transfer that label into stream 2. */
1388
1389 static void
1390 find_cross_jump (e1, e2, minimum, f1, f2)
1391 rtx e1, e2;
1392 int minimum;
1393 rtx *f1, *f2;
1394 {
1395 register rtx i1 = e1, i2 = e2;
1396 register rtx p1, p2;
1397 int lose = 0;
1398
1399 rtx last1 = 0, last2 = 0;
1400 rtx afterlast1 = 0, afterlast2 = 0;
1401
1402 *f1 = 0;
1403 *f2 = 0;
1404
1405 while (1)
1406 {
1407 i1 = prev_nonnote_insn (i1);
1408
1409 i2 = PREV_INSN (i2);
1410 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
1411 i2 = PREV_INSN (i2);
1412
1413 if (i1 == 0)
1414 break;
1415
1416 /* Don't allow the range of insns preceding E1 or E2
1417 to include the other (E2 or E1). */
1418 if (i2 == e1 || i1 == e2)
1419 break;
1420
1421 /* If we will get to this code by jumping, those jumps will be
1422 tensioned to go directly to the new label (before I2),
1423 so this cross-jumping won't cost extra. So reduce the minimum. */
1424 if (GET_CODE (i1) == CODE_LABEL)
1425 {
1426 --minimum;
1427 break;
1428 }
1429
1430 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
1431 break;
1432
1433 p1 = PATTERN (i1);
1434 p2 = PATTERN (i2);
1435
1436 /* If this is a CALL_INSN, compare register usage information.
1437 If we don't check this on stack register machines, the two
1438 CALL_INSNs might be merged leaving reg-stack.c with mismatching
1439 numbers of stack registers in the same basic block.
1440 If we don't check this on machines with delay slots, a delay slot may
1441 be filled that clobbers a parameter expected by the subroutine.
1442
1443 ??? We take the simple route for now and assume that if they're
1444 equal, they were constructed identically. */
1445
1446 if (GET_CODE (i1) == CALL_INSN
1447 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1448 CALL_INSN_FUNCTION_USAGE (i2)))
1449 lose = 1;
1450
1451 #ifdef STACK_REGS
1452 /* If cross_jump_death_matters is not 0, the insn's mode
1453 indicates whether or not the insn contains any stack-like
1454 regs. */
1455
1456 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
1457 {
1458 /* If register stack conversion has already been done, then
1459 death notes must also be compared before it is certain that
1460 the two instruction streams match. */
1461
1462 rtx note;
1463 HARD_REG_SET i1_regset, i2_regset;
1464
1465 CLEAR_HARD_REG_SET (i1_regset);
1466 CLEAR_HARD_REG_SET (i2_regset);
1467
1468 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
1469 if (REG_NOTE_KIND (note) == REG_DEAD
1470 && STACK_REG_P (XEXP (note, 0)))
1471 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
1472
1473 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1474 if (REG_NOTE_KIND (note) == REG_DEAD
1475 && STACK_REG_P (XEXP (note, 0)))
1476 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1477
1478 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
1479
1480 lose = 1;
1481
1482 done:
1483 ;
1484 }
1485 #endif
1486
1487 /* Don't allow old-style asm or volatile extended asms to be accepted
1488 for cross jumping purposes. It is conceptually correct to allow
1489 them, since cross-jumping preserves the dynamic instruction order
1490 even though it is changing the static instruction order. However,
1491 if an asm is being used to emit an assembler pseudo-op, such as
1492 the MIPS `.set reorder' pseudo-op, then the static instruction order
1493 matters and it must be preserved. */
1494 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
1495 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
1496 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
1497 lose = 1;
1498
1499 if (lose || GET_CODE (p1) != GET_CODE (p2)
1500 || ! rtx_renumbered_equal_p (p1, p2))
1501 {
1502 /* The following code helps take care of G++ cleanups. */
1503 rtx equiv1;
1504 rtx equiv2;
1505
1506 if (!lose && GET_CODE (p1) == GET_CODE (p2)
1507 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
1508 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
1509 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
1510 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
1511 /* If the equivalences are not to a constant, they may
1512 reference pseudos that no longer exist, so we can't
1513 use them. */
1514 && CONSTANT_P (XEXP (equiv1, 0))
1515 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1516 {
1517 rtx s1 = single_set (i1);
1518 rtx s2 = single_set (i2);
1519 if (s1 != 0 && s2 != 0
1520 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
1521 {
1522 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
1523 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
1524 if (! rtx_renumbered_equal_p (p1, p2))
1525 cancel_changes (0);
1526 else if (apply_change_group ())
1527 goto win;
1528 }
1529 }
1530
1531 /* Insns fail to match; cross jumping is limited to the following
1532 insns. */
1533
1534 #ifdef HAVE_cc0
1535 /* Don't allow the insn after a compare to be shared by
1536 cross-jumping unless the compare is also shared.
1537 Here, if either of these non-matching insns is a compare,
1538 exclude the following insn from possible cross-jumping. */
1539 if (sets_cc0_p (p1) || sets_cc0_p (p2))
1540 last1 = afterlast1, last2 = afterlast2, ++minimum;
1541 #endif
1542
1543 /* If cross-jumping here will feed a jump-around-jump
1544 optimization, this jump won't cost extra, so reduce
1545 the minimum. */
1546 if (GET_CODE (i1) == JUMP_INSN
1547 && JUMP_LABEL (i1)
1548 && prev_real_insn (JUMP_LABEL (i1)) == e1)
1549 --minimum;
1550 break;
1551 }
1552
1553 win:
1554 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
1555 {
1556 /* Ok, this insn is potentially includable in a cross-jump here. */
1557 afterlast1 = last1, afterlast2 = last2;
1558 last1 = i1, last2 = i2, --minimum;
1559 }
1560 }
1561
1562 if (minimum <= 0 && last1 != 0 && last1 != e1)
1563 *f1 = last1, *f2 = last2;
1564 }
1565
1566 static void
1567 do_cross_jump (insn, newjpos, newlpos)
1568 rtx insn, newjpos, newlpos;
1569 {
1570 /* Find an existing label at this point
1571 or make a new one if there is none. */
1572 register rtx label = get_label_before (newlpos);
1573
1574 /* Make the same jump insn jump to the new point. */
1575 if (GET_CODE (PATTERN (insn)) == RETURN)
1576 {
1577 /* Remove from jump chain of returns. */
1578 delete_from_jump_chain (insn);
1579 /* Change the insn. */
1580 PATTERN (insn) = gen_jump (label);
1581 INSN_CODE (insn) = -1;
1582 JUMP_LABEL (insn) = label;
1583 LABEL_NUSES (label)++;
1584 /* Add to new the jump chain. */
1585 if (INSN_UID (label) < max_jump_chain
1586 && INSN_UID (insn) < max_jump_chain)
1587 {
1588 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
1589 jump_chain[INSN_UID (label)] = insn;
1590 }
1591 }
1592 else
1593 redirect_jump (insn, label, 1);
1594
1595 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
1596 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
1597 the NEWJPOS stream. */
1598
1599 while (newjpos != insn)
1600 {
1601 rtx lnote;
1602
1603 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
1604 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
1605 || REG_NOTE_KIND (lnote) == REG_EQUIV)
1606 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
1607 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
1608 remove_note (newlpos, lnote);
1609
1610 delete_insn (newjpos);
1611 newjpos = next_real_insn (newjpos);
1612 newlpos = next_real_insn (newlpos);
1613 }
1614 }
1615 \f
1616 /* Return the label before INSN, or put a new label there. */
1617
1618 rtx
1619 get_label_before (insn)
1620 rtx insn;
1621 {
1622 rtx label;
1623
1624 /* Find an existing label at this point
1625 or make a new one if there is none. */
1626 label = prev_nonnote_insn (insn);
1627
1628 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1629 {
1630 rtx prev = PREV_INSN (insn);
1631
1632 label = gen_label_rtx ();
1633 emit_label_after (label, prev);
1634 LABEL_NUSES (label) = 0;
1635 }
1636 return label;
1637 }
1638
1639 /* Return the label after INSN, or put a new label there. */
1640
1641 rtx
1642 get_label_after (insn)
1643 rtx insn;
1644 {
1645 rtx label;
1646
1647 /* Find an existing label at this point
1648 or make a new one if there is none. */
1649 label = next_nonnote_insn (insn);
1650
1651 if (label == 0 || GET_CODE (label) != CODE_LABEL)
1652 {
1653 label = gen_label_rtx ();
1654 emit_label_after (label, insn);
1655 LABEL_NUSES (label) = 0;
1656 }
1657 return label;
1658 }
1659 \f
1660 /* Return 1 if INSN is a jump that jumps to right after TARGET
1661 only on the condition that TARGET itself would drop through.
1662 Assumes that TARGET is a conditional jump. */
1663
1664 static int
1665 jump_back_p (insn, target)
1666 rtx insn, target;
1667 {
1668 rtx cinsn, ctarget;
1669 enum rtx_code codei, codet;
1670 rtx set, tset;
1671
1672 if (! any_condjump_p (insn)
1673 || any_uncondjump_p (target)
1674 || target != prev_real_insn (JUMP_LABEL (insn)))
1675 return 0;
1676 set = pc_set (insn);
1677 tset = pc_set (target);
1678
1679 cinsn = XEXP (SET_SRC (set), 0);
1680 ctarget = XEXP (SET_SRC (tset), 0);
1681
1682 codei = GET_CODE (cinsn);
1683 codet = GET_CODE (ctarget);
1684
1685 if (XEXP (SET_SRC (set), 1) == pc_rtx)
1686 {
1687 codei = reversed_comparison_code (cinsn, insn);
1688 if (codei == UNKNOWN)
1689 return 0;
1690 }
1691
1692 if (XEXP (SET_SRC (tset), 2) == pc_rtx)
1693 {
1694 codet = reversed_comparison_code (ctarget, target);
1695 if (codei == UNKNOWN)
1696 return 0;
1697 }
1698
1699 return (codei == codet
1700 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
1701 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
1702 }
1703 \f
1704 /* Given a comparison (CODE ARG0 ARG1), inside a insn, INSN, return an code
1705 of reversed comparison if it is possible to do so. Otherwise return UNKNOWN.
1706 UNKNOWN may be returned in case we are having CC_MODE compare and we don't
1707 know whether it's source is floating point or integer comparison. Machine
1708 description should define REVERSIBLE_CC_MODE and REVERSE_CONDITION macros
1709 to help this function avoid overhead in these cases. */
1710 enum rtx_code
1711 reversed_comparison_code_parts (code, arg0, arg1, insn)
1712 rtx insn, arg0, arg1;
1713 enum rtx_code code;
1714 {
1715 enum machine_mode mode;
1716
1717 /* If this is not actually a comparison, we can't reverse it. */
1718 if (GET_RTX_CLASS (code) != '<')
1719 return UNKNOWN;
1720
1721 mode = GET_MODE (arg0);
1722 if (mode == VOIDmode)
1723 mode = GET_MODE (arg1);
1724
1725 /* First see if machine description supply us way to reverse the comparison.
1726 Give it priority over everything else to allow machine description to do
1727 tricks. */
1728 #ifdef REVERSIBLE_CC_MODE
1729 if (GET_MODE_CLASS (mode) == MODE_CC
1730 && REVERSIBLE_CC_MODE (mode))
1731 {
1732 #ifdef REVERSE_CONDITION
1733 return REVERSE_CONDITION (code, mode);
1734 #endif
1735 return reverse_condition (code);
1736 }
1737 #endif
1738
1739 /* Try few special cases based on the comparison code. */
1740 switch (code)
1741 {
1742 case GEU:
1743 case GTU:
1744 case LEU:
1745 case LTU:
1746 case NE:
1747 case EQ:
1748 /* It is always safe to reverse EQ and NE, even for the floating
1749 point. Similary the unsigned comparisons are never used for
1750 floating point so we can reverse them in the default way. */
1751 return reverse_condition (code);
1752 case ORDERED:
1753 case UNORDERED:
1754 case LTGT:
1755 case UNEQ:
1756 /* In case we already see unordered comparison, we can be sure to
1757 be dealing with floating point so we don't need any more tests. */
1758 return reverse_condition_maybe_unordered (code);
1759 case UNLT:
1760 case UNLE:
1761 case UNGT:
1762 case UNGE:
1763 /* We don't have safe way to reverse these yet. */
1764 return UNKNOWN;
1765 default:
1766 break;
1767 }
1768
1769 /* In case we give up IEEE compatibility, all comparisons are reversible. */
1770 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
1771 || flag_unsafe_math_optimizations)
1772 return reverse_condition (code);
1773
1774 if (GET_MODE_CLASS (mode) == MODE_CC
1775 #ifdef HAVE_cc0
1776 || arg0 == cc0_rtx
1777 #endif
1778 )
1779 {
1780 rtx prev;
1781 /* Try to search for the comparison to determine the real mode.
1782 This code is expensive, but with sane machine description it
1783 will be never used, since REVERSIBLE_CC_MODE will return true
1784 in all cases. */
1785 if (! insn)
1786 return UNKNOWN;
1787
1788 for (prev = prev_nonnote_insn (insn);
1789 prev != 0 && GET_CODE (prev) != CODE_LABEL;
1790 prev = prev_nonnote_insn (prev))
1791 {
1792 rtx set = set_of (arg0, prev);
1793 if (set && GET_CODE (set) == SET
1794 && rtx_equal_p (SET_DEST (set), arg0))
1795 {
1796 rtx src = SET_SRC (set);
1797
1798 if (GET_CODE (src) == COMPARE)
1799 {
1800 rtx comparison = src;
1801 arg0 = XEXP (src, 0);
1802 mode = GET_MODE (arg0);
1803 if (mode == VOIDmode)
1804 mode = GET_MODE (XEXP (comparison, 1));
1805 break;
1806 }
1807 /* We can get past reg-reg moves. This may be usefull for model
1808 of i387 comparisons that first move flag registers around. */
1809 if (REG_P (src))
1810 {
1811 arg0 = src;
1812 continue;
1813 }
1814 }
1815 /* If register is clobbered in some ununderstandable way,
1816 give up. */
1817 if (set)
1818 return UNKNOWN;
1819 }
1820 }
1821
1822 /* An integer condition. */
1823 if (GET_CODE (arg0) == CONST_INT
1824 || (GET_MODE (arg0) != VOIDmode
1825 && GET_MODE_CLASS (mode) != MODE_CC
1826 && ! FLOAT_MODE_P (mode)))
1827 return reverse_condition (code);
1828
1829 return UNKNOWN;
1830 }
1831
1832 /* An wrapper around the previous function to take COMPARISON as rtx
1833 expression. This simplifies many callers. */
1834 enum rtx_code
1835 reversed_comparison_code (comparison, insn)
1836 rtx comparison, insn;
1837 {
1838 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
1839 return UNKNOWN;
1840 return reversed_comparison_code_parts (GET_CODE (comparison),
1841 XEXP (comparison, 0),
1842 XEXP (comparison, 1), insn);
1843 }
1844 \f
1845 /* Given an rtx-code for a comparison, return the code for the negated
1846 comparison. If no such code exists, return UNKNOWN.
1847
1848 WATCH OUT! reverse_condition is not safe to use on a jump that might
1849 be acting on the results of an IEEE floating point comparison, because
1850 of the special treatment of non-signaling nans in comparisons.
1851 Use reversed_comparison_code instead. */
1852
1853 enum rtx_code
1854 reverse_condition (code)
1855 enum rtx_code code;
1856 {
1857 switch (code)
1858 {
1859 case EQ:
1860 return NE;
1861 case NE:
1862 return EQ;
1863 case GT:
1864 return LE;
1865 case GE:
1866 return LT;
1867 case LT:
1868 return GE;
1869 case LE:
1870 return GT;
1871 case GTU:
1872 return LEU;
1873 case GEU:
1874 return LTU;
1875 case LTU:
1876 return GEU;
1877 case LEU:
1878 return GTU;
1879 case UNORDERED:
1880 return ORDERED;
1881 case ORDERED:
1882 return UNORDERED;
1883
1884 case UNLT:
1885 case UNLE:
1886 case UNGT:
1887 case UNGE:
1888 case UNEQ:
1889 case LTGT:
1890 return UNKNOWN;
1891
1892 default:
1893 abort ();
1894 }
1895 }
1896
1897 /* Similar, but we're allowed to generate unordered comparisons, which
1898 makes it safe for IEEE floating-point. Of course, we have to recognize
1899 that the target will support them too... */
1900
1901 enum rtx_code
1902 reverse_condition_maybe_unordered (code)
1903 enum rtx_code code;
1904 {
1905 /* Non-IEEE formats don't have unordered conditions. */
1906 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
1907 return reverse_condition (code);
1908
1909 switch (code)
1910 {
1911 case EQ:
1912 return NE;
1913 case NE:
1914 return EQ;
1915 case GT:
1916 return UNLE;
1917 case GE:
1918 return UNLT;
1919 case LT:
1920 return UNGE;
1921 case LE:
1922 return UNGT;
1923 case LTGT:
1924 return UNEQ;
1925 case UNORDERED:
1926 return ORDERED;
1927 case ORDERED:
1928 return UNORDERED;
1929 case UNLT:
1930 return GE;
1931 case UNLE:
1932 return GT;
1933 case UNGT:
1934 return LE;
1935 case UNGE:
1936 return LT;
1937 case UNEQ:
1938 return LTGT;
1939
1940 default:
1941 abort ();
1942 }
1943 }
1944
1945 /* Similar, but return the code when two operands of a comparison are swapped.
1946 This IS safe for IEEE floating-point. */
1947
1948 enum rtx_code
1949 swap_condition (code)
1950 enum rtx_code code;
1951 {
1952 switch (code)
1953 {
1954 case EQ:
1955 case NE:
1956 case UNORDERED:
1957 case ORDERED:
1958 case UNEQ:
1959 case LTGT:
1960 return code;
1961
1962 case GT:
1963 return LT;
1964 case GE:
1965 return LE;
1966 case LT:
1967 return GT;
1968 case LE:
1969 return GE;
1970 case GTU:
1971 return LTU;
1972 case GEU:
1973 return LEU;
1974 case LTU:
1975 return GTU;
1976 case LEU:
1977 return GEU;
1978 case UNLT:
1979 return UNGT;
1980 case UNLE:
1981 return UNGE;
1982 case UNGT:
1983 return UNLT;
1984 case UNGE:
1985 return UNLE;
1986
1987 default:
1988 abort ();
1989 }
1990 }
1991
1992 /* Given a comparison CODE, return the corresponding unsigned comparison.
1993 If CODE is an equality comparison or already an unsigned comparison,
1994 CODE is returned. */
1995
1996 enum rtx_code
1997 unsigned_condition (code)
1998 enum rtx_code code;
1999 {
2000 switch (code)
2001 {
2002 case EQ:
2003 case NE:
2004 case GTU:
2005 case GEU:
2006 case LTU:
2007 case LEU:
2008 return code;
2009
2010 case GT:
2011 return GTU;
2012 case GE:
2013 return GEU;
2014 case LT:
2015 return LTU;
2016 case LE:
2017 return LEU;
2018
2019 default:
2020 abort ();
2021 }
2022 }
2023
2024 /* Similarly, return the signed version of a comparison. */
2025
2026 enum rtx_code
2027 signed_condition (code)
2028 enum rtx_code code;
2029 {
2030 switch (code)
2031 {
2032 case EQ:
2033 case NE:
2034 case GT:
2035 case GE:
2036 case LT:
2037 case LE:
2038 return code;
2039
2040 case GTU:
2041 return GT;
2042 case GEU:
2043 return GE;
2044 case LTU:
2045 return LT;
2046 case LEU:
2047 return LE;
2048
2049 default:
2050 abort ();
2051 }
2052 }
2053 \f
2054 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2055 truth of CODE1 implies the truth of CODE2. */
2056
2057 int
2058 comparison_dominates_p (code1, code2)
2059 enum rtx_code code1, code2;
2060 {
2061 /* UNKNOWN comparison codes can happen as a result of trying to revert
2062 comparison codes.
2063 They can't match anything, so we have to reject them here. */
2064 if (code1 == UNKNOWN || code2 == UNKNOWN)
2065 return 0;
2066
2067 if (code1 == code2)
2068 return 1;
2069
2070 switch (code1)
2071 {
2072 case UNEQ:
2073 if (code2 == UNLE || code2 == UNGE)
2074 return 1;
2075 break;
2076
2077 case EQ:
2078 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
2079 || code2 == ORDERED)
2080 return 1;
2081 break;
2082
2083 case UNLT:
2084 if (code2 == UNLE || code2 == NE)
2085 return 1;
2086 break;
2087
2088 case LT:
2089 if (code2 == LE || code2 == NE || code2 == ORDERED || code2 == LTGT)
2090 return 1;
2091 break;
2092
2093 case UNGT:
2094 if (code2 == UNGE || code2 == NE)
2095 return 1;
2096 break;
2097
2098 case GT:
2099 if (code2 == GE || code2 == NE || code2 == ORDERED || code2 == LTGT)
2100 return 1;
2101 break;
2102
2103 case GE:
2104 case LE:
2105 if (code2 == ORDERED)
2106 return 1;
2107 break;
2108
2109 case LTGT:
2110 if (code2 == NE || code2 == ORDERED)
2111 return 1;
2112 break;
2113
2114 case LTU:
2115 if (code2 == LEU || code2 == NE)
2116 return 1;
2117 break;
2118
2119 case GTU:
2120 if (code2 == GEU || code2 == NE)
2121 return 1;
2122 break;
2123
2124 case UNORDERED:
2125 if (code2 == NE || code2 == UNEQ || code2 == UNLE || code2 == UNLT
2126 || code2 == UNGE || code2 == UNGT)
2127 return 1;
2128 break;
2129
2130 default:
2131 break;
2132 }
2133
2134 return 0;
2135 }
2136 \f
2137 /* Return 1 if INSN is an unconditional jump and nothing else. */
2138
2139 int
2140 simplejump_p (insn)
2141 rtx insn;
2142 {
2143 return (GET_CODE (insn) == JUMP_INSN
2144 && GET_CODE (PATTERN (insn)) == SET
2145 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2146 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2147 }
2148
2149 /* Return nonzero if INSN is a (possibly) conditional jump
2150 and nothing more.
2151
2152 Use this function is deprecated, since we need to support combined
2153 branch and compare insns. Use any_condjump_p instead whenever possible. */
2154
2155 int
2156 condjump_p (insn)
2157 rtx insn;
2158 {
2159 register rtx x = PATTERN (insn);
2160
2161 if (GET_CODE (x) != SET
2162 || GET_CODE (SET_DEST (x)) != PC)
2163 return 0;
2164
2165 x = SET_SRC (x);
2166 if (GET_CODE (x) == LABEL_REF)
2167 return 1;
2168 else
2169 return (GET_CODE (x) == IF_THEN_ELSE
2170 && ((GET_CODE (XEXP (x, 2)) == PC
2171 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
2172 || GET_CODE (XEXP (x, 1)) == RETURN))
2173 || (GET_CODE (XEXP (x, 1)) == PC
2174 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
2175 || GET_CODE (XEXP (x, 2)) == RETURN))));
2176
2177 return 0;
2178 }
2179
2180 /* Return nonzero if INSN is a (possibly) conditional jump inside a
2181 PARALLEL.
2182
2183 Use this function is deprecated, since we need to support combined
2184 branch and compare insns. Use any_condjump_p instead whenever possible. */
2185
2186 int
2187 condjump_in_parallel_p (insn)
2188 rtx insn;
2189 {
2190 register rtx x = PATTERN (insn);
2191
2192 if (GET_CODE (x) != PARALLEL)
2193 return 0;
2194 else
2195 x = XVECEXP (x, 0, 0);
2196
2197 if (GET_CODE (x) != SET)
2198 return 0;
2199 if (GET_CODE (SET_DEST (x)) != PC)
2200 return 0;
2201 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2202 return 1;
2203 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2204 return 0;
2205 if (XEXP (SET_SRC (x), 2) == pc_rtx
2206 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2207 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2208 return 1;
2209 if (XEXP (SET_SRC (x), 1) == pc_rtx
2210 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2211 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2212 return 1;
2213 return 0;
2214 }
2215
2216 /* Return set of PC, otherwise NULL. */
2217
2218 rtx
2219 pc_set (insn)
2220 rtx insn;
2221 {
2222 rtx pat;
2223 if (GET_CODE (insn) != JUMP_INSN)
2224 return NULL_RTX;
2225 pat = PATTERN (insn);
2226
2227 /* The set is allowed to appear either as the insn pattern or
2228 the first set in a PARALLEL. */
2229 if (GET_CODE (pat) == PARALLEL)
2230 pat = XVECEXP (pat, 0, 0);
2231 if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
2232 return pat;
2233
2234 return NULL_RTX;
2235 }
2236
2237 /* Return true when insn is an unconditional direct jump,
2238 possibly bundled inside a PARALLEL. */
2239
2240 int
2241 any_uncondjump_p (insn)
2242 rtx insn;
2243 {
2244 rtx x = pc_set (insn);
2245 if (!x)
2246 return 0;
2247 if (GET_CODE (SET_SRC (x)) != LABEL_REF)
2248 return 0;
2249 return 1;
2250 }
2251
2252 /* Return true when insn is a conditional jump. This function works for
2253 instructions containing PC sets in PARALLELs. The instruction may have
2254 various other effects so before removing the jump you must verify
2255 onlyjump_p.
2256
2257 Note that unlike condjump_p it returns false for unconditional jumps. */
2258
2259 int
2260 any_condjump_p (insn)
2261 rtx insn;
2262 {
2263 rtx x = pc_set (insn);
2264 enum rtx_code a, b;
2265
2266 if (!x)
2267 return 0;
2268 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2269 return 0;
2270
2271 a = GET_CODE (XEXP (SET_SRC (x), 1));
2272 b = GET_CODE (XEXP (SET_SRC (x), 2));
2273
2274 return ((b == PC && (a == LABEL_REF || a == RETURN))
2275 || (a == PC && (b == LABEL_REF || b == RETURN)));
2276 }
2277
2278 /* Return the label of a conditional jump. */
2279
2280 rtx
2281 condjump_label (insn)
2282 rtx insn;
2283 {
2284 rtx x = pc_set (insn);
2285
2286 if (!x)
2287 return NULL_RTX;
2288 x = SET_SRC (x);
2289 if (GET_CODE (x) == LABEL_REF)
2290 return x;
2291 if (GET_CODE (x) != IF_THEN_ELSE)
2292 return NULL_RTX;
2293 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
2294 return XEXP (x, 1);
2295 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
2296 return XEXP (x, 2);
2297 return NULL_RTX;
2298 }
2299
2300 /* Return true if INSN is a (possibly conditional) return insn. */
2301
2302 static int
2303 returnjump_p_1 (loc, data)
2304 rtx *loc;
2305 void *data ATTRIBUTE_UNUSED;
2306 {
2307 rtx x = *loc;
2308 return x && GET_CODE (x) == RETURN;
2309 }
2310
2311 int
2312 returnjump_p (insn)
2313 rtx insn;
2314 {
2315 if (GET_CODE (insn) != JUMP_INSN)
2316 return 0;
2317 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
2318 }
2319
2320 /* Return true if INSN is a jump that only transfers control and
2321 nothing more. */
2322
2323 int
2324 onlyjump_p (insn)
2325 rtx insn;
2326 {
2327 rtx set;
2328
2329 if (GET_CODE (insn) != JUMP_INSN)
2330 return 0;
2331
2332 set = single_set (insn);
2333 if (set == NULL)
2334 return 0;
2335 if (GET_CODE (SET_DEST (set)) != PC)
2336 return 0;
2337 if (side_effects_p (SET_SRC (set)))
2338 return 0;
2339
2340 return 1;
2341 }
2342
2343 #ifdef HAVE_cc0
2344
2345 /* Return 1 if X is an RTX that does nothing but set the condition codes
2346 and CLOBBER or USE registers.
2347 Return -1 if X does explicitly set the condition codes,
2348 but also does other things. */
2349
2350 int
2351 sets_cc0_p (x)
2352 rtx x ATTRIBUTE_UNUSED;
2353 {
2354 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2355 return 1;
2356 if (GET_CODE (x) == PARALLEL)
2357 {
2358 int i;
2359 int sets_cc0 = 0;
2360 int other_things = 0;
2361 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2362 {
2363 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2364 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2365 sets_cc0 = 1;
2366 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2367 other_things = 1;
2368 }
2369 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2370 }
2371 return 0;
2372 }
2373 #endif
2374 \f
2375 /* Follow any unconditional jump at LABEL;
2376 return the ultimate label reached by any such chain of jumps.
2377 If LABEL is not followed by a jump, return LABEL.
2378 If the chain loops or we can't find end, return LABEL,
2379 since that tells caller to avoid changing the insn.
2380
2381 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2382 a USE or CLOBBER. */
2383
2384 rtx
2385 follow_jumps (label)
2386 rtx label;
2387 {
2388 register rtx insn;
2389 register rtx next;
2390 register rtx value = label;
2391 register int depth;
2392
2393 for (depth = 0;
2394 (depth < 10
2395 && (insn = next_active_insn (value)) != 0
2396 && GET_CODE (insn) == JUMP_INSN
2397 && ((JUMP_LABEL (insn) != 0 && any_uncondjump_p (insn)
2398 && onlyjump_p (insn))
2399 || GET_CODE (PATTERN (insn)) == RETURN)
2400 && (next = NEXT_INSN (insn))
2401 && GET_CODE (next) == BARRIER);
2402 depth++)
2403 {
2404 /* Don't chain through the insn that jumps into a loop
2405 from outside the loop,
2406 since that would create multiple loop entry jumps
2407 and prevent loop optimization. */
2408 rtx tem;
2409 if (!reload_completed)
2410 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2411 if (GET_CODE (tem) == NOTE
2412 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
2413 /* ??? Optional. Disables some optimizations, but makes
2414 gcov output more accurate with -O. */
2415 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
2416 return value;
2417
2418 /* If we have found a cycle, make the insn jump to itself. */
2419 if (JUMP_LABEL (insn) == label)
2420 return label;
2421
2422 tem = next_active_insn (JUMP_LABEL (insn));
2423 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
2424 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
2425 break;
2426
2427 value = JUMP_LABEL (insn);
2428 }
2429 if (depth == 10)
2430 return label;
2431 return value;
2432 }
2433
2434 /* Assuming that field IDX of X is a vector of label_refs,
2435 replace each of them by the ultimate label reached by it.
2436 Return nonzero if a change is made.
2437 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2438
2439 static int
2440 tension_vector_labels (x, idx)
2441 register rtx x;
2442 register int idx;
2443 {
2444 int changed = 0;
2445 register int i;
2446 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2447 {
2448 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2449 register rtx nlabel = follow_jumps (olabel);
2450 if (nlabel && nlabel != olabel)
2451 {
2452 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2453 ++LABEL_NUSES (nlabel);
2454 if (--LABEL_NUSES (olabel) == 0)
2455 delete_insn (olabel);
2456 changed = 1;
2457 }
2458 }
2459 return changed;
2460 }
2461 \f
2462 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2463 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2464 in INSN, then store one of them in JUMP_LABEL (INSN).
2465 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2466 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2467 Also, when there are consecutive labels, canonicalize on the last of them.
2468
2469 Note that two labels separated by a loop-beginning note
2470 must be kept distinct if we have not yet done loop-optimization,
2471 because the gap between them is where loop-optimize
2472 will want to move invariant code to. CROSS_JUMP tells us
2473 that loop-optimization is done with.
2474
2475 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2476 two labels distinct if they are separated by only USE or CLOBBER insns. */
2477
2478 void
2479 mark_jump_label (x, insn, cross_jump, in_mem)
2480 register rtx x;
2481 rtx insn;
2482 int cross_jump;
2483 int in_mem;
2484 {
2485 register RTX_CODE code = GET_CODE (x);
2486 register int i;
2487 register const char *fmt;
2488
2489 switch (code)
2490 {
2491 case PC:
2492 case CC0:
2493 case REG:
2494 case SUBREG:
2495 case CONST_INT:
2496 case CONST_DOUBLE:
2497 case CLOBBER:
2498 case CALL:
2499 return;
2500
2501 case MEM:
2502 in_mem = 1;
2503 break;
2504
2505 case SYMBOL_REF:
2506 if (!in_mem)
2507 return;
2508
2509 /* If this is a constant-pool reference, see if it is a label. */
2510 if (CONSTANT_POOL_ADDRESS_P (x))
2511 mark_jump_label (get_pool_constant (x), insn, cross_jump, in_mem);
2512 break;
2513
2514 case LABEL_REF:
2515 {
2516 rtx label = XEXP (x, 0);
2517 rtx olabel = label;
2518 rtx next;
2519
2520 /* Ignore remaining references to unreachable labels that
2521 have been deleted. */
2522 if (GET_CODE (label) == NOTE
2523 && NOTE_LINE_NUMBER (label) == NOTE_INSN_DELETED_LABEL)
2524 break;
2525
2526 if (GET_CODE (label) != CODE_LABEL)
2527 abort ();
2528
2529 /* Ignore references to labels of containing functions. */
2530 if (LABEL_REF_NONLOCAL_P (x))
2531 break;
2532
2533 /* If there are other labels following this one,
2534 replace it with the last of the consecutive labels. */
2535 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
2536 {
2537 if (GET_CODE (next) == CODE_LABEL)
2538 label = next;
2539 else if (cross_jump && GET_CODE (next) == INSN
2540 && (GET_CODE (PATTERN (next)) == USE
2541 || GET_CODE (PATTERN (next)) == CLOBBER))
2542 continue;
2543 else if (GET_CODE (next) != NOTE)
2544 break;
2545 else if (! cross_jump
2546 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
2547 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
2548 /* ??? Optional. Disables some optimizations, but
2549 makes gcov output more accurate with -O. */
2550 || (flag_test_coverage
2551 && NOTE_LINE_NUMBER (next) > 0)))
2552 break;
2553 }
2554
2555 XEXP (x, 0) = label;
2556 if (! insn || ! INSN_DELETED_P (insn))
2557 ++LABEL_NUSES (label);
2558
2559 if (insn)
2560 {
2561 if (GET_CODE (insn) == JUMP_INSN)
2562 JUMP_LABEL (insn) = label;
2563 else
2564 {
2565 /* If we've changed the label, update notes accordingly. */
2566 if (label != olabel)
2567 {
2568 rtx note;
2569
2570 /* We may have a REG_LABEL note to indicate that this
2571 instruction uses the label. */
2572 note = find_reg_note (insn, REG_LABEL, olabel);
2573 if (note)
2574 XEXP (note, 0) = label;
2575
2576 /* We may also have a REG_EQUAL note to indicate that
2577 a register is being set to the address of the
2578 label. */
2579 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
2580 if (note
2581 && GET_CODE (XEXP (note, 0)) == LABEL_REF
2582 && XEXP (XEXP (note, 0), 0) == olabel)
2583 XEXP (XEXP (note, 0), 0) = label;
2584 }
2585
2586 /* Add a REG_LABEL note for LABEL unless there already
2587 is one. All uses of a label, except for labels
2588 that are the targets of jumps, must have a
2589 REG_LABEL note. */
2590 if (! find_reg_note (insn, REG_LABEL, label))
2591 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
2592 REG_NOTES (insn));
2593 }
2594 }
2595 return;
2596 }
2597
2598 /* Do walk the labels in a vector, but not the first operand of an
2599 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2600 case ADDR_VEC:
2601 case ADDR_DIFF_VEC:
2602 if (! INSN_DELETED_P (insn))
2603 {
2604 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
2605
2606 for (i = 0; i < XVECLEN (x, eltnum); i++)
2607 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX,
2608 cross_jump, in_mem);
2609 }
2610 return;
2611
2612 default:
2613 break;
2614 }
2615
2616 fmt = GET_RTX_FORMAT (code);
2617 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2618 {
2619 if (fmt[i] == 'e')
2620 mark_jump_label (XEXP (x, i), insn, cross_jump, in_mem);
2621 else if (fmt[i] == 'E')
2622 {
2623 register int j;
2624 for (j = 0; j < XVECLEN (x, i); j++)
2625 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump, in_mem);
2626 }
2627 }
2628 }
2629
2630 /* If all INSN does is set the pc, delete it,
2631 and delete the insn that set the condition codes for it
2632 if that's what the previous thing was. */
2633
2634 void
2635 delete_jump (insn)
2636 rtx insn;
2637 {
2638 register rtx set = single_set (insn);
2639
2640 if (set && GET_CODE (SET_DEST (set)) == PC)
2641 delete_computation (insn);
2642 }
2643
2644 /* Verify INSN is a BARRIER and delete it. */
2645
2646 void
2647 delete_barrier (insn)
2648 rtx insn;
2649 {
2650 if (GET_CODE (insn) != BARRIER)
2651 abort ();
2652
2653 delete_insn (insn);
2654 }
2655
2656 /* Recursively delete prior insns that compute the value (used only by INSN
2657 which the caller is deleting) stored in the register mentioned by NOTE
2658 which is a REG_DEAD note associated with INSN. */
2659
2660 static void
2661 delete_prior_computation (note, insn)
2662 rtx note;
2663 rtx insn;
2664 {
2665 rtx our_prev;
2666 rtx reg = XEXP (note, 0);
2667
2668 for (our_prev = prev_nonnote_insn (insn);
2669 our_prev && (GET_CODE (our_prev) == INSN
2670 || GET_CODE (our_prev) == CALL_INSN);
2671 our_prev = prev_nonnote_insn (our_prev))
2672 {
2673 rtx pat = PATTERN (our_prev);
2674
2675 /* If we reach a CALL which is not calling a const function
2676 or the callee pops the arguments, then give up. */
2677 if (GET_CODE (our_prev) == CALL_INSN
2678 && (! CONST_CALL_P (our_prev)
2679 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
2680 break;
2681
2682 /* If we reach a SEQUENCE, it is too complex to try to
2683 do anything with it, so give up. */
2684 if (GET_CODE (pat) == SEQUENCE)
2685 break;
2686
2687 if (GET_CODE (pat) == USE
2688 && GET_CODE (XEXP (pat, 0)) == INSN)
2689 /* reorg creates USEs that look like this. We leave them
2690 alone because reorg needs them for its own purposes. */
2691 break;
2692
2693 if (reg_set_p (reg, pat))
2694 {
2695 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
2696 break;
2697
2698 if (GET_CODE (pat) == PARALLEL)
2699 {
2700 /* If we find a SET of something else, we can't
2701 delete the insn. */
2702
2703 int i;
2704
2705 for (i = 0; i < XVECLEN (pat, 0); i++)
2706 {
2707 rtx part = XVECEXP (pat, 0, i);
2708
2709 if (GET_CODE (part) == SET
2710 && SET_DEST (part) != reg)
2711 break;
2712 }
2713
2714 if (i == XVECLEN (pat, 0))
2715 delete_computation (our_prev);
2716 }
2717 else if (GET_CODE (pat) == SET
2718 && GET_CODE (SET_DEST (pat)) == REG)
2719 {
2720 int dest_regno = REGNO (SET_DEST (pat));
2721 int dest_endregno
2722 = (dest_regno
2723 + (dest_regno < FIRST_PSEUDO_REGISTER
2724 ? HARD_REGNO_NREGS (dest_regno,
2725 GET_MODE (SET_DEST (pat))) : 1));
2726 int regno = REGNO (reg);
2727 int endregno
2728 = (regno
2729 + (regno < FIRST_PSEUDO_REGISTER
2730 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1));
2731
2732 if (dest_regno >= regno
2733 && dest_endregno <= endregno)
2734 delete_computation (our_prev);
2735
2736 /* We may have a multi-word hard register and some, but not
2737 all, of the words of the register are needed in subsequent
2738 insns. Write REG_UNUSED notes for those parts that were not
2739 needed. */
2740 else if (dest_regno <= regno
2741 && dest_endregno >= endregno)
2742 {
2743 int i;
2744
2745 REG_NOTES (our_prev)
2746 = gen_rtx_EXPR_LIST (REG_UNUSED, reg,
2747 REG_NOTES (our_prev));
2748
2749 for (i = dest_regno; i < dest_endregno; i++)
2750 if (! find_regno_note (our_prev, REG_UNUSED, i))
2751 break;
2752
2753 if (i == dest_endregno)
2754 delete_computation (our_prev);
2755 }
2756 }
2757
2758 break;
2759 }
2760
2761 /* If PAT references the register that dies here, it is an
2762 additional use. Hence any prior SET isn't dead. However, this
2763 insn becomes the new place for the REG_DEAD note. */
2764 if (reg_overlap_mentioned_p (reg, pat))
2765 {
2766 XEXP (note, 1) = REG_NOTES (our_prev);
2767 REG_NOTES (our_prev) = note;
2768 break;
2769 }
2770 }
2771 }
2772
2773 /* Delete INSN and recursively delete insns that compute values used only
2774 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2775 If we are running before flow.c, we need do nothing since flow.c will
2776 delete dead code. We also can't know if the registers being used are
2777 dead or not at this point.
2778
2779 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2780 nothing other than set a register that dies in this insn, we can delete
2781 that insn as well.
2782
2783 On machines with CC0, if CC0 is used in this insn, we may be able to
2784 delete the insn that set it. */
2785
2786 static void
2787 delete_computation (insn)
2788 rtx insn;
2789 {
2790 rtx note, next;
2791
2792 #ifdef HAVE_cc0
2793 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
2794 {
2795 rtx prev = prev_nonnote_insn (insn);
2796 /* We assume that at this stage
2797 CC's are always set explicitly
2798 and always immediately before the jump that
2799 will use them. So if the previous insn
2800 exists to set the CC's, delete it
2801 (unless it performs auto-increments, etc.). */
2802 if (prev && GET_CODE (prev) == INSN
2803 && sets_cc0_p (PATTERN (prev)))
2804 {
2805 if (sets_cc0_p (PATTERN (prev)) > 0
2806 && ! side_effects_p (PATTERN (prev)))
2807 delete_computation (prev);
2808 else
2809 /* Otherwise, show that cc0 won't be used. */
2810 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
2811 cc0_rtx, REG_NOTES (prev));
2812 }
2813 }
2814 #endif
2815
2816 for (note = REG_NOTES (insn); note; note = next)
2817 {
2818 next = XEXP (note, 1);
2819
2820 if (REG_NOTE_KIND (note) != REG_DEAD
2821 /* Verify that the REG_NOTE is legitimate. */
2822 || GET_CODE (XEXP (note, 0)) != REG)
2823 continue;
2824
2825 delete_prior_computation (note, insn);
2826 }
2827
2828 delete_insn (insn);
2829 }
2830 \f
2831 /* Delete insn INSN from the chain of insns and update label ref counts.
2832 May delete some following insns as a consequence; may even delete
2833 a label elsewhere and insns that follow it.
2834
2835 Returns the first insn after INSN that was not deleted. */
2836
2837 rtx
2838 delete_insn (insn)
2839 register rtx insn;
2840 {
2841 register rtx next = NEXT_INSN (insn);
2842 register rtx prev = PREV_INSN (insn);
2843 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
2844 register int dont_really_delete = 0;
2845 rtx note;
2846
2847 while (next && INSN_DELETED_P (next))
2848 next = NEXT_INSN (next);
2849
2850 /* This insn is already deleted => return first following nondeleted. */
2851 if (INSN_DELETED_P (insn))
2852 return next;
2853
2854 if (was_code_label)
2855 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2856
2857 /* Don't delete user-declared labels. When optimizing, convert them
2858 to special NOTEs instead. When not optimizing, leave them alone. */
2859 if (was_code_label && LABEL_NAME (insn) != 0)
2860 {
2861 if (optimize)
2862 {
2863 const char *name = LABEL_NAME (insn);
2864 PUT_CODE (insn, NOTE);
2865 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
2866 NOTE_SOURCE_FILE (insn) = name;
2867 }
2868
2869 dont_really_delete = 1;
2870 }
2871 else
2872 /* Mark this insn as deleted. */
2873 INSN_DELETED_P (insn) = 1;
2874
2875 /* If this is an unconditional jump, delete it from the jump chain. */
2876 if (simplejump_p (insn))
2877 delete_from_jump_chain (insn);
2878
2879 /* If instruction is followed by a barrier,
2880 delete the barrier too. */
2881
2882 if (next != 0 && GET_CODE (next) == BARRIER)
2883 {
2884 INSN_DELETED_P (next) = 1;
2885 next = NEXT_INSN (next);
2886 }
2887
2888 /* Patch out INSN (and the barrier if any) */
2889
2890 if (! dont_really_delete)
2891 {
2892 if (prev)
2893 {
2894 NEXT_INSN (prev) = next;
2895 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
2896 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
2897 XVECLEN (PATTERN (prev), 0) - 1)) = next;
2898 }
2899
2900 if (next)
2901 {
2902 PREV_INSN (next) = prev;
2903 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
2904 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
2905 }
2906
2907 if (prev && NEXT_INSN (prev) == 0)
2908 set_last_insn (prev);
2909 }
2910
2911 /* If deleting a jump, decrement the count of the label,
2912 and delete the label if it is now unused. */
2913
2914 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
2915 {
2916 rtx lab = JUMP_LABEL (insn), lab_next;
2917
2918 if (--LABEL_NUSES (lab) == 0)
2919 {
2920 /* This can delete NEXT or PREV,
2921 either directly if NEXT is JUMP_LABEL (INSN),
2922 or indirectly through more levels of jumps. */
2923 delete_insn (lab);
2924
2925 /* I feel a little doubtful about this loop,
2926 but I see no clean and sure alternative way
2927 to find the first insn after INSN that is not now deleted.
2928 I hope this works. */
2929 while (next && INSN_DELETED_P (next))
2930 next = NEXT_INSN (next);
2931 return next;
2932 }
2933 else if ((lab_next = next_nonnote_insn (lab)) != NULL
2934 && GET_CODE (lab_next) == JUMP_INSN
2935 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
2936 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
2937 {
2938 /* If we're deleting the tablejump, delete the dispatch table.
2939 We may not be able to kill the label immediately preceeding
2940 just yet, as it might be referenced in code leading up to
2941 the tablejump. */
2942 delete_insn (lab_next);
2943 }
2944 }
2945
2946 /* Likewise if we're deleting a dispatch table. */
2947
2948 if (GET_CODE (insn) == JUMP_INSN
2949 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2950 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2951 {
2952 rtx pat = PATTERN (insn);
2953 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2954 int len = XVECLEN (pat, diff_vec_p);
2955
2956 for (i = 0; i < len; i++)
2957 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
2958 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
2959 while (next && INSN_DELETED_P (next))
2960 next = NEXT_INSN (next);
2961 return next;
2962 }
2963
2964 /* Likewise for an ordinary INSN / CALL_INSN with a REG_LABEL note. */
2965 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2966 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2967 if (REG_NOTE_KIND (note) == REG_LABEL
2968 /* This could also be a NOTE_INSN_DELETED_LABEL note. */
2969 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2970 if (--LABEL_NUSES (XEXP (note, 0)) == 0)
2971 delete_insn (XEXP (note, 0));
2972
2973 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
2974 prev = PREV_INSN (prev);
2975
2976 /* If INSN was a label and a dispatch table follows it,
2977 delete the dispatch table. The tablejump must have gone already.
2978 It isn't useful to fall through into a table. */
2979
2980 if (was_code_label
2981 && NEXT_INSN (insn) != 0
2982 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
2983 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
2984 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
2985 next = delete_insn (NEXT_INSN (insn));
2986
2987 /* If INSN was a label, delete insns following it if now unreachable. */
2988
2989 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
2990 {
2991 register RTX_CODE code;
2992 while (next != 0
2993 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
2994 || code == NOTE || code == BARRIER
2995 || (code == CODE_LABEL && INSN_DELETED_P (next))))
2996 {
2997 if (code == NOTE
2998 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
2999 next = NEXT_INSN (next);
3000 /* Keep going past other deleted labels to delete what follows. */
3001 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3002 next = NEXT_INSN (next);
3003 else
3004 /* Note: if this deletes a jump, it can cause more
3005 deletion of unreachable code, after a different label.
3006 As long as the value from this recursive call is correct,
3007 this invocation functions correctly. */
3008 next = delete_insn (next);
3009 }
3010 }
3011
3012 return next;
3013 }
3014
3015 /* Advance from INSN till reaching something not deleted
3016 then return that. May return INSN itself. */
3017
3018 rtx
3019 next_nondeleted_insn (insn)
3020 rtx insn;
3021 {
3022 while (INSN_DELETED_P (insn))
3023 insn = NEXT_INSN (insn);
3024 return insn;
3025 }
3026 \f
3027 /* Delete a range of insns from FROM to TO, inclusive.
3028 This is for the sake of peephole optimization, so assume
3029 that whatever these insns do will still be done by a new
3030 peephole insn that will replace them. */
3031
3032 void
3033 delete_for_peephole (from, to)
3034 register rtx from, to;
3035 {
3036 register rtx insn = from;
3037
3038 while (1)
3039 {
3040 register rtx next = NEXT_INSN (insn);
3041 register rtx prev = PREV_INSN (insn);
3042
3043 if (GET_CODE (insn) != NOTE)
3044 {
3045 INSN_DELETED_P (insn) = 1;
3046
3047 /* Patch this insn out of the chain. */
3048 /* We don't do this all at once, because we
3049 must preserve all NOTEs. */
3050 if (prev)
3051 NEXT_INSN (prev) = next;
3052
3053 if (next)
3054 PREV_INSN (next) = prev;
3055 }
3056
3057 if (insn == to)
3058 break;
3059 insn = next;
3060 }
3061
3062 /* Note that if TO is an unconditional jump
3063 we *do not* delete the BARRIER that follows,
3064 since the peephole that replaces this sequence
3065 is also an unconditional jump in that case. */
3066 }
3067 \f
3068 /* We have determined that INSN is never reached, and are about to
3069 delete it. Print a warning if the user asked for one.
3070
3071 To try to make this warning more useful, this should only be called
3072 once per basic block not reached, and it only warns when the basic
3073 block contains more than one line from the current function, and
3074 contains at least one operation. CSE and inlining can duplicate insns,
3075 so it's possible to get spurious warnings from this. */
3076
3077 void
3078 never_reached_warning (avoided_insn)
3079 rtx avoided_insn;
3080 {
3081 rtx insn;
3082 rtx a_line_note = NULL;
3083 int two_avoided_lines = 0;
3084 int contains_insn = 0;
3085
3086 if (! warn_notreached)
3087 return;
3088
3089 /* Scan forwards, looking at LINE_NUMBER notes, until
3090 we hit a LABEL or we run out of insns. */
3091
3092 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
3093 {
3094 if (GET_CODE (insn) == CODE_LABEL)
3095 break;
3096 else if (GET_CODE (insn) == NOTE /* A line number note? */
3097 && NOTE_LINE_NUMBER (insn) >= 0)
3098 {
3099 if (a_line_note == NULL)
3100 a_line_note = insn;
3101 else
3102 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
3103 != NOTE_LINE_NUMBER (insn));
3104 }
3105 else if (INSN_P (insn))
3106 contains_insn = 1;
3107 }
3108 if (two_avoided_lines && contains_insn)
3109 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
3110 NOTE_LINE_NUMBER (a_line_note),
3111 "will never be executed");
3112 }
3113 \f
3114 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
3115 NLABEL as a return. Accrue modifications into the change group. */
3116
3117 static void
3118 redirect_exp_1 (loc, olabel, nlabel, insn)
3119 rtx *loc;
3120 rtx olabel, nlabel;
3121 rtx insn;
3122 {
3123 register rtx x = *loc;
3124 register RTX_CODE code = GET_CODE (x);
3125 register int i;
3126 register const char *fmt;
3127
3128 if (code == LABEL_REF)
3129 {
3130 if (XEXP (x, 0) == olabel)
3131 {
3132 rtx n;
3133 if (nlabel)
3134 n = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3135 else
3136 n = gen_rtx_RETURN (VOIDmode);
3137
3138 validate_change (insn, loc, n, 1);
3139 return;
3140 }
3141 }
3142 else if (code == RETURN && olabel == 0)
3143 {
3144 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3145 if (loc == &PATTERN (insn))
3146 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
3147 validate_change (insn, loc, x, 1);
3148 return;
3149 }
3150
3151 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3152 && GET_CODE (SET_SRC (x)) == LABEL_REF
3153 && XEXP (SET_SRC (x), 0) == olabel)
3154 {
3155 validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 1);
3156 return;
3157 }
3158
3159 fmt = GET_RTX_FORMAT (code);
3160 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3161 {
3162 if (fmt[i] == 'e')
3163 redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
3164 else if (fmt[i] == 'E')
3165 {
3166 register int j;
3167 for (j = 0; j < XVECLEN (x, i); j++)
3168 redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
3169 }
3170 }
3171 }
3172
3173 /* Similar, but apply the change group and report success or failure. */
3174
3175 static int
3176 redirect_exp (olabel, nlabel, insn)
3177 rtx olabel, nlabel;
3178 rtx insn;
3179 {
3180 rtx *loc;
3181
3182 if (GET_CODE (PATTERN (insn)) == PARALLEL)
3183 loc = &XVECEXP (PATTERN (insn), 0, 0);
3184 else
3185 loc = &PATTERN (insn);
3186
3187 redirect_exp_1 (loc, olabel, nlabel, insn);
3188 if (num_validated_changes () == 0)
3189 return 0;
3190
3191 return apply_change_group ();
3192 }
3193
3194 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
3195 the modifications into the change group. Return false if we did
3196 not see how to do that. */
3197
3198 int
3199 redirect_jump_1 (jump, nlabel)
3200 rtx jump, nlabel;
3201 {
3202 int ochanges = num_validated_changes ();
3203 rtx *loc;
3204
3205 if (GET_CODE (PATTERN (jump)) == PARALLEL)
3206 loc = &XVECEXP (PATTERN (jump), 0, 0);
3207 else
3208 loc = &PATTERN (jump);
3209
3210 redirect_exp_1 (loc, JUMP_LABEL (jump), nlabel, jump);
3211 return num_validated_changes () > ochanges;
3212 }
3213
3214 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
3215 jump target label is unused as a result, it and the code following
3216 it may be deleted.
3217
3218 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3219 RETURN insn.
3220
3221 The return value will be 1 if the change was made, 0 if it wasn't
3222 (this can only occur for NLABEL == 0). */
3223
3224 int
3225 redirect_jump (jump, nlabel, delete_unused)
3226 rtx jump, nlabel;
3227 int delete_unused;
3228 {
3229 register rtx olabel = JUMP_LABEL (jump);
3230
3231 if (nlabel == olabel)
3232 return 1;
3233
3234 if (! redirect_exp (olabel, nlabel, jump))
3235 return 0;
3236
3237 /* If this is an unconditional branch, delete it from the jump_chain of
3238 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3239 have UID's in range and JUMP_CHAIN is valid). */
3240 if (jump_chain && (simplejump_p (jump)
3241 || GET_CODE (PATTERN (jump)) == RETURN))
3242 {
3243 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3244
3245 delete_from_jump_chain (jump);
3246 if (label_index < max_jump_chain
3247 && INSN_UID (jump) < max_jump_chain)
3248 {
3249 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3250 jump_chain[label_index] = jump;
3251 }
3252 }
3253
3254 JUMP_LABEL (jump) = nlabel;
3255 if (nlabel)
3256 ++LABEL_NUSES (nlabel);
3257
3258 /* If we're eliding the jump over exception cleanups at the end of a
3259 function, move the function end note so that -Wreturn-type works. */
3260 if (olabel && nlabel
3261 && NEXT_INSN (olabel)
3262 && GET_CODE (NEXT_INSN (olabel)) == NOTE
3263 && NOTE_LINE_NUMBER (NEXT_INSN (olabel)) == NOTE_INSN_FUNCTION_END)
3264 emit_note_after (NOTE_INSN_FUNCTION_END, nlabel);
3265
3266 if (olabel && --LABEL_NUSES (olabel) == 0 && delete_unused)
3267 delete_insn (olabel);
3268
3269 return 1;
3270 }
3271
3272 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3273 Accrue the modifications into the change group. */
3274
3275 static void
3276 invert_exp_1 (insn)
3277 rtx insn;
3278 {
3279 register RTX_CODE code;
3280 rtx x = pc_set (insn);
3281
3282 if (!x)
3283 abort ();
3284 x = SET_SRC (x);
3285
3286 code = GET_CODE (x);
3287
3288 if (code == IF_THEN_ELSE)
3289 {
3290 register rtx comp = XEXP (x, 0);
3291 register rtx tem;
3292 enum rtx_code reversed_code;
3293
3294 /* We can do this in two ways: The preferable way, which can only
3295 be done if this is not an integer comparison, is to reverse
3296 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3297 of the IF_THEN_ELSE. If we can't do either, fail. */
3298
3299 reversed_code = reversed_comparison_code (comp, insn);
3300
3301 if (reversed_code != UNKNOWN)
3302 {
3303 validate_change (insn, &XEXP (x, 0),
3304 gen_rtx_fmt_ee (reversed_code,
3305 GET_MODE (comp), XEXP (comp, 0),
3306 XEXP (comp, 1)),
3307 1);
3308 return;
3309 }
3310
3311 tem = XEXP (x, 1);
3312 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3313 validate_change (insn, &XEXP (x, 2), tem, 1);
3314 }
3315 else
3316 abort ();
3317 }
3318
3319 /* Invert the jump condition of conditional jump insn, INSN.
3320
3321 Return 1 if we can do so, 0 if we cannot find a way to do so that
3322 matches a pattern. */
3323
3324 static int
3325 invert_exp (insn)
3326 rtx insn;
3327 {
3328 invert_exp_1 (insn);
3329 if (num_validated_changes () == 0)
3330 return 0;
3331
3332 return apply_change_group ();
3333 }
3334
3335 /* Invert the condition of the jump JUMP, and make it jump to label
3336 NLABEL instead of where it jumps now. Accrue changes into the
3337 change group. Return false if we didn't see how to perform the
3338 inversion and redirection. */
3339
3340 int
3341 invert_jump_1 (jump, nlabel)
3342 rtx jump, nlabel;
3343 {
3344 int ochanges;
3345
3346 ochanges = num_validated_changes ();
3347 invert_exp_1 (jump);
3348 if (num_validated_changes () == ochanges)
3349 return 0;
3350
3351 return redirect_jump_1 (jump, nlabel);
3352 }
3353
3354 /* Invert the condition of the jump JUMP, and make it jump to label
3355 NLABEL instead of where it jumps now. Return true if successful. */
3356
3357 int
3358 invert_jump (jump, nlabel, delete_unused)
3359 rtx jump, nlabel;
3360 int delete_unused;
3361 {
3362 /* We have to either invert the condition and change the label or
3363 do neither. Either operation could fail. We first try to invert
3364 the jump. If that succeeds, we try changing the label. If that fails,
3365 we invert the jump back to what it was. */
3366
3367 if (! invert_exp (jump))
3368 return 0;
3369
3370 if (redirect_jump (jump, nlabel, delete_unused))
3371 {
3372 invert_br_probabilities (jump);
3373
3374 return 1;
3375 }
3376
3377 if (! invert_exp (jump))
3378 /* This should just be putting it back the way it was. */
3379 abort ();
3380
3381 return 0;
3382 }
3383
3384 /* Delete the instruction JUMP from any jump chain it might be on. */
3385
3386 static void
3387 delete_from_jump_chain (jump)
3388 rtx jump;
3389 {
3390 int index;
3391 rtx olabel = JUMP_LABEL (jump);
3392
3393 /* Handle unconditional jumps. */
3394 if (jump_chain && olabel != 0
3395 && INSN_UID (olabel) < max_jump_chain
3396 && simplejump_p (jump))
3397 index = INSN_UID (olabel);
3398 /* Handle return insns. */
3399 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3400 index = 0;
3401 else
3402 return;
3403
3404 if (jump_chain[index] == jump)
3405 jump_chain[index] = jump_chain[INSN_UID (jump)];
3406 else
3407 {
3408 rtx insn;
3409
3410 for (insn = jump_chain[index];
3411 insn != 0;
3412 insn = jump_chain[INSN_UID (insn)])
3413 if (jump_chain[INSN_UID (insn)] == jump)
3414 {
3415 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3416 break;
3417 }
3418 }
3419 }
3420 \f
3421 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3422
3423 If the old jump target label (before the dispatch table) becomes unused,
3424 it and the dispatch table may be deleted. In that case, find the insn
3425 before the jump references that label and delete it and logical successors
3426 too. */
3427
3428 static void
3429 redirect_tablejump (jump, nlabel)
3430 rtx jump, nlabel;
3431 {
3432 register rtx olabel = JUMP_LABEL (jump);
3433 rtx *notep, note, next;
3434
3435 /* Add this jump to the jump_chain of NLABEL. */
3436 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3437 && INSN_UID (jump) < max_jump_chain)
3438 {
3439 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3440 jump_chain[INSN_UID (nlabel)] = jump;
3441 }
3442
3443 for (notep = &REG_NOTES (jump), note = *notep; note; note = next)
3444 {
3445 next = XEXP (note, 1);
3446
3447 if (REG_NOTE_KIND (note) != REG_DEAD
3448 /* Verify that the REG_NOTE is legitimate. */
3449 || GET_CODE (XEXP (note, 0)) != REG
3450 || ! reg_mentioned_p (XEXP (note, 0), PATTERN (jump)))
3451 notep = &XEXP (note, 1);
3452 else
3453 {
3454 delete_prior_computation (note, jump);
3455 *notep = next;
3456 }
3457 }
3458
3459 PATTERN (jump) = gen_jump (nlabel);
3460 JUMP_LABEL (jump) = nlabel;
3461 ++LABEL_NUSES (nlabel);
3462 INSN_CODE (jump) = -1;
3463
3464 if (--LABEL_NUSES (olabel) == 0)
3465 {
3466 delete_labelref_insn (jump, olabel, 0);
3467 delete_insn (olabel);
3468 }
3469 }
3470
3471 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3472 If we found one, delete it and then delete this insn if DELETE_THIS is
3473 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3474
3475 static int
3476 delete_labelref_insn (insn, label, delete_this)
3477 rtx insn, label;
3478 int delete_this;
3479 {
3480 int deleted = 0;
3481 rtx link;
3482
3483 if (GET_CODE (insn) != NOTE
3484 && reg_mentioned_p (label, PATTERN (insn)))
3485 {
3486 if (delete_this)
3487 {
3488 delete_insn (insn);
3489 deleted = 1;
3490 }
3491 else
3492 return 1;
3493 }
3494
3495 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3496 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3497 {
3498 if (delete_this)
3499 {
3500 delete_insn (insn);
3501 deleted = 1;
3502 }
3503 else
3504 return 1;
3505 }
3506
3507 return deleted;
3508 }
3509 \f
3510 /* Like rtx_equal_p except that it considers two REGs as equal
3511 if they renumber to the same value and considers two commutative
3512 operations to be the same if the order of the operands has been
3513 reversed.
3514
3515 ??? Addition is not commutative on the PA due to the weird implicit
3516 space register selection rules for memory addresses. Therefore, we
3517 don't consider a + b == b + a.
3518
3519 We could/should make this test a little tighter. Possibly only
3520 disabling it on the PA via some backend macro or only disabling this
3521 case when the PLUS is inside a MEM. */
3522
3523 int
3524 rtx_renumbered_equal_p (x, y)
3525 rtx x, y;
3526 {
3527 register int i;
3528 register RTX_CODE code = GET_CODE (x);
3529 register const char *fmt;
3530
3531 if (x == y)
3532 return 1;
3533
3534 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3535 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3536 && GET_CODE (SUBREG_REG (y)) == REG)))
3537 {
3538 int reg_x = -1, reg_y = -1;
3539 int byte_x = 0, byte_y = 0;
3540
3541 if (GET_MODE (x) != GET_MODE (y))
3542 return 0;
3543
3544 /* If we haven't done any renumbering, don't
3545 make any assumptions. */
3546 if (reg_renumber == 0)
3547 return rtx_equal_p (x, y);
3548
3549 if (code == SUBREG)
3550 {
3551 reg_x = REGNO (SUBREG_REG (x));
3552 byte_x = SUBREG_BYTE (x);
3553
3554 if (reg_renumber[reg_x] >= 0)
3555 {
3556 reg_x = subreg_regno_offset (reg_renumber[reg_x],
3557 GET_MODE (SUBREG_REG (x)),
3558 byte_x,
3559 GET_MODE (x));
3560 byte_x = 0;
3561 }
3562 }
3563 else
3564 {
3565 reg_x = REGNO (x);
3566 if (reg_renumber[reg_x] >= 0)
3567 reg_x = reg_renumber[reg_x];
3568 }
3569
3570 if (GET_CODE (y) == SUBREG)
3571 {
3572 reg_y = REGNO (SUBREG_REG (y));
3573 byte_y = SUBREG_BYTE (y);
3574
3575 if (reg_renumber[reg_y] >= 0)
3576 {
3577 reg_y = subreg_regno_offset (reg_renumber[reg_y],
3578 GET_MODE (SUBREG_REG (y)),
3579 byte_y,
3580 GET_MODE (y));
3581 byte_y = 0;
3582 }
3583 }
3584 else
3585 {
3586 reg_y = REGNO (y);
3587 if (reg_renumber[reg_y] >= 0)
3588 reg_y = reg_renumber[reg_y];
3589 }
3590
3591 return reg_x >= 0 && reg_x == reg_y && byte_x == byte_y;
3592 }
3593
3594 /* Now we have disposed of all the cases
3595 in which different rtx codes can match. */
3596 if (code != GET_CODE (y))
3597 return 0;
3598
3599 switch (code)
3600 {
3601 case PC:
3602 case CC0:
3603 case ADDR_VEC:
3604 case ADDR_DIFF_VEC:
3605 return 0;
3606
3607 case CONST_INT:
3608 return INTVAL (x) == INTVAL (y);
3609
3610 case LABEL_REF:
3611 /* We can't assume nonlocal labels have their following insns yet. */
3612 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3613 return XEXP (x, 0) == XEXP (y, 0);
3614
3615 /* Two label-refs are equivalent if they point at labels
3616 in the same position in the instruction stream. */
3617 return (next_real_insn (XEXP (x, 0))
3618 == next_real_insn (XEXP (y, 0)));
3619
3620 case SYMBOL_REF:
3621 return XSTR (x, 0) == XSTR (y, 0);
3622
3623 case CODE_LABEL:
3624 /* If we didn't match EQ equality above, they aren't the same. */
3625 return 0;
3626
3627 default:
3628 break;
3629 }
3630
3631 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3632
3633 if (GET_MODE (x) != GET_MODE (y))
3634 return 0;
3635
3636 /* For commutative operations, the RTX match if the operand match in any
3637 order. Also handle the simple binary and unary cases without a loop.
3638
3639 ??? Don't consider PLUS a commutative operator; see comments above. */
3640 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3641 && code != PLUS)
3642 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3643 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
3644 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
3645 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
3646 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3647 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3648 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
3649 else if (GET_RTX_CLASS (code) == '1')
3650 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
3651
3652 /* Compare the elements. If any pair of corresponding elements
3653 fail to match, return 0 for the whole things. */
3654
3655 fmt = GET_RTX_FORMAT (code);
3656 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3657 {
3658 register int j;
3659 switch (fmt[i])
3660 {
3661 case 'w':
3662 if (XWINT (x, i) != XWINT (y, i))
3663 return 0;
3664 break;
3665
3666 case 'i':
3667 if (XINT (x, i) != XINT (y, i))
3668 return 0;
3669 break;
3670
3671 case 's':
3672 if (strcmp (XSTR (x, i), XSTR (y, i)))
3673 return 0;
3674 break;
3675
3676 case 'e':
3677 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3678 return 0;
3679 break;
3680
3681 case 'u':
3682 if (XEXP (x, i) != XEXP (y, i))
3683 return 0;
3684 /* fall through. */
3685 case '0':
3686 break;
3687
3688 case 'E':
3689 if (XVECLEN (x, i) != XVECLEN (y, i))
3690 return 0;
3691 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3692 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3693 return 0;
3694 break;
3695
3696 default:
3697 abort ();
3698 }
3699 }
3700 return 1;
3701 }
3702 \f
3703 /* If X is a hard register or equivalent to one or a subregister of one,
3704 return the hard register number. If X is a pseudo register that was not
3705 assigned a hard register, return the pseudo register number. Otherwise,
3706 return -1. Any rtx is valid for X. */
3707
3708 int
3709 true_regnum (x)
3710 rtx x;
3711 {
3712 if (GET_CODE (x) == REG)
3713 {
3714 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3715 return reg_renumber[REGNO (x)];
3716 return REGNO (x);
3717 }
3718 if (GET_CODE (x) == SUBREG)
3719 {
3720 int base = true_regnum (SUBREG_REG (x));
3721 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3722 return base + subreg_regno_offset (REGNO (SUBREG_REG (x)),
3723 GET_MODE (SUBREG_REG (x)),
3724 SUBREG_BYTE (x), GET_MODE (x));
3725 }
3726 return -1;
3727 }
3728 \f
3729 /* Optimize code of the form:
3730
3731 for (x = a[i]; x; ...)
3732 ...
3733 for (x = a[i]; x; ...)
3734 ...
3735 foo:
3736
3737 Loop optimize will change the above code into
3738
3739 if (x = a[i])
3740 for (;;)
3741 { ...; if (! (x = ...)) break; }
3742 if (x = a[i])
3743 for (;;)
3744 { ...; if (! (x = ...)) break; }
3745 foo:
3746
3747 In general, if the first test fails, the program can branch
3748 directly to `foo' and skip the second try which is doomed to fail.
3749 We run this after loop optimization and before flow analysis. */
3750
3751 /* When comparing the insn patterns, we track the fact that different
3752 pseudo-register numbers may have been used in each computation.
3753 The following array stores an equivalence -- same_regs[I] == J means
3754 that pseudo register I was used in the first set of tests in a context
3755 where J was used in the second set. We also count the number of such
3756 pending equivalences. If nonzero, the expressions really aren't the
3757 same. */
3758
3759 static int *same_regs;
3760
3761 static int num_same_regs;
3762
3763 /* Track any registers modified between the target of the first jump and
3764 the second jump. They never compare equal. */
3765
3766 static char *modified_regs;
3767
3768 /* Record if memory was modified. */
3769
3770 static int modified_mem;
3771
3772 /* Called via note_stores on each insn between the target of the first
3773 branch and the second branch. It marks any changed registers. */
3774
3775 static void
3776 mark_modified_reg (dest, x, data)
3777 rtx dest;
3778 rtx x;
3779 void *data ATTRIBUTE_UNUSED;
3780 {
3781 int regno;
3782 unsigned int i;
3783
3784 if (GET_CODE (dest) == SUBREG)
3785 dest = SUBREG_REG (dest);
3786
3787 if (GET_CODE (dest) == MEM)
3788 modified_mem = 1;
3789
3790 if (GET_CODE (dest) != REG)
3791 return;
3792
3793 regno = REGNO (dest);
3794 if (regno >= FIRST_PSEUDO_REGISTER)
3795 modified_regs[regno] = 1;
3796 /* Don't consider a hard condition code register as modified,
3797 if it is only being set. thread_jumps will check if it is set
3798 to the same value. */
3799 else if (GET_MODE_CLASS (GET_MODE (dest)) != MODE_CC
3800 || GET_CODE (x) != SET
3801 || ! rtx_equal_p (dest, SET_DEST (x))
3802 || HARD_REGNO_NREGS (regno, GET_MODE (dest)) != 1)
3803 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3804 modified_regs[regno + i] = 1;
3805 }
3806
3807 /* F is the first insn in the chain of insns. */
3808
3809 void
3810 thread_jumps (f, max_reg, flag_before_loop)
3811 rtx f;
3812 int max_reg;
3813 int flag_before_loop;
3814 {
3815 /* Basic algorithm is to find a conditional branch,
3816 the label it may branch to, and the branch after
3817 that label. If the two branches test the same condition,
3818 walk back from both branch paths until the insn patterns
3819 differ, or code labels are hit. If we make it back to
3820 the target of the first branch, then we know that the first branch
3821 will either always succeed or always fail depending on the relative
3822 senses of the two branches. So adjust the first branch accordingly
3823 in this case. */
3824
3825 rtx label, b1, b2, t1, t2;
3826 enum rtx_code code1, code2;
3827 rtx b1op0, b1op1, b2op0, b2op1;
3828 int changed = 1;
3829 int i;
3830 int *all_reset;
3831 enum rtx_code reversed_code1, reversed_code2;
3832
3833 /* Allocate register tables and quick-reset table. */
3834 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
3835 same_regs = (int *) xmalloc (max_reg * sizeof (int));
3836 all_reset = (int *) xmalloc (max_reg * sizeof (int));
3837 for (i = 0; i < max_reg; i++)
3838 all_reset[i] = -1;
3839
3840 while (changed)
3841 {
3842 changed = 0;
3843
3844 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3845 {
3846 rtx set;
3847 rtx set2;
3848
3849 /* Get to a candidate branch insn. */
3850 if (GET_CODE (b1) != JUMP_INSN
3851 || ! any_condjump_p (b1) || JUMP_LABEL (b1) == 0)
3852 continue;
3853
3854 memset (modified_regs, 0, max_reg * sizeof (char));
3855 modified_mem = 0;
3856
3857 memcpy (same_regs, all_reset, max_reg * sizeof (int));
3858 num_same_regs = 0;
3859
3860 label = JUMP_LABEL (b1);
3861
3862 /* Look for a branch after the target. Record any registers and
3863 memory modified between the target and the branch. Stop when we
3864 get to a label since we can't know what was changed there. */
3865 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
3866 {
3867 if (GET_CODE (b2) == CODE_LABEL)
3868 break;
3869
3870 else if (GET_CODE (b2) == JUMP_INSN)
3871 {
3872 /* If this is an unconditional jump and is the only use of
3873 its target label, we can follow it. */
3874 if (any_uncondjump_p (b2)
3875 && onlyjump_p (b2)
3876 && JUMP_LABEL (b2) != 0
3877 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
3878 {
3879 b2 = JUMP_LABEL (b2);
3880 continue;
3881 }
3882 else
3883 break;
3884 }
3885
3886 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
3887 continue;
3888
3889 if (GET_CODE (b2) == CALL_INSN)
3890 {
3891 modified_mem = 1;
3892 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3893 if (call_used_regs[i] && ! fixed_regs[i]
3894 && i != STACK_POINTER_REGNUM
3895 && i != FRAME_POINTER_REGNUM
3896 && i != HARD_FRAME_POINTER_REGNUM
3897 && i != ARG_POINTER_REGNUM)
3898 modified_regs[i] = 1;
3899 }
3900
3901 note_stores (PATTERN (b2), mark_modified_reg, NULL);
3902 }
3903
3904 /* Check the next candidate branch insn from the label
3905 of the first. */
3906 if (b2 == 0
3907 || GET_CODE (b2) != JUMP_INSN
3908 || b2 == b1
3909 || !any_condjump_p (b2)
3910 || !onlyjump_p (b2))
3911 continue;
3912 set = pc_set (b1);
3913 set2 = pc_set (b2);
3914
3915 /* Get the comparison codes and operands, reversing the
3916 codes if appropriate. If we don't have comparison codes,
3917 we can't do anything. */
3918 b1op0 = XEXP (XEXP (SET_SRC (set), 0), 0);
3919 b1op1 = XEXP (XEXP (SET_SRC (set), 0), 1);
3920 code1 = GET_CODE (XEXP (SET_SRC (set), 0));
3921 reversed_code1 = code1;
3922 if (XEXP (SET_SRC (set), 1) == pc_rtx)
3923 code1 = reversed_comparison_code (XEXP (SET_SRC (set), 0), b1);
3924 else
3925 reversed_code1 = reversed_comparison_code (XEXP (SET_SRC (set), 0), b1);
3926
3927 b2op0 = XEXP (XEXP (SET_SRC (set2), 0), 0);
3928 b2op1 = XEXP (XEXP (SET_SRC (set2), 0), 1);
3929 code2 = GET_CODE (XEXP (SET_SRC (set2), 0));
3930 reversed_code2 = code2;
3931 if (XEXP (SET_SRC (set2), 1) == pc_rtx)
3932 code2 = reversed_comparison_code (XEXP (SET_SRC (set2), 0), b2);
3933 else
3934 reversed_code2 = reversed_comparison_code (XEXP (SET_SRC (set2), 0), b2);
3935
3936 /* If they test the same things and knowing that B1 branches
3937 tells us whether or not B2 branches, check if we
3938 can thread the branch. */
3939 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
3940 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
3941 && (comparison_dominates_p (code1, code2)
3942 || comparison_dominates_p (code1, reversed_code2)))
3943
3944 {
3945 t1 = prev_nonnote_insn (b1);
3946 t2 = prev_nonnote_insn (b2);
3947
3948 while (t1 != 0 && t2 != 0)
3949 {
3950 if (t2 == label)
3951 {
3952 /* We have reached the target of the first branch.
3953 If there are no pending register equivalents,
3954 we know that this branch will either always
3955 succeed (if the senses of the two branches are
3956 the same) or always fail (if not). */
3957 rtx new_label;
3958
3959 if (num_same_regs != 0)
3960 break;
3961
3962 if (comparison_dominates_p (code1, code2))
3963 new_label = JUMP_LABEL (b2);
3964 else
3965 new_label = get_label_after (b2);
3966
3967 if (JUMP_LABEL (b1) != new_label)
3968 {
3969 rtx prev = PREV_INSN (new_label);
3970
3971 if (flag_before_loop
3972 && GET_CODE (prev) == NOTE
3973 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
3974 {
3975 /* Don't thread to the loop label. If a loop
3976 label is reused, loop optimization will
3977 be disabled for that loop. */
3978 new_label = gen_label_rtx ();
3979 emit_label_after (new_label, PREV_INSN (prev));
3980 }
3981 changed |= redirect_jump (b1, new_label, 1);
3982 }
3983 break;
3984 }
3985
3986 /* If either of these is not a normal insn (it might be
3987 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3988 have already been skipped above.) Similarly, fail
3989 if the insns are different. */
3990 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
3991 || recog_memoized (t1) != recog_memoized (t2)
3992 || ! rtx_equal_for_thread_p (PATTERN (t1),
3993 PATTERN (t2), t2))
3994 break;
3995
3996 t1 = prev_nonnote_insn (t1);
3997 t2 = prev_nonnote_insn (t2);
3998 }
3999 }
4000 }
4001 }
4002
4003 /* Clean up. */
4004 free (modified_regs);
4005 free (same_regs);
4006 free (all_reset);
4007 }
4008 \f
4009 /* This is like RTX_EQUAL_P except that it knows about our handling of
4010 possibly equivalent registers and knows to consider volatile and
4011 modified objects as not equal.
4012
4013 YINSN is the insn containing Y. */
4014
4015 int
4016 rtx_equal_for_thread_p (x, y, yinsn)
4017 rtx x, y;
4018 rtx yinsn;
4019 {
4020 register int i;
4021 register int j;
4022 register enum rtx_code code;
4023 register const char *fmt;
4024
4025 code = GET_CODE (x);
4026 /* Rtx's of different codes cannot be equal. */
4027 if (code != GET_CODE (y))
4028 return 0;
4029
4030 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4031 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4032
4033 if (GET_MODE (x) != GET_MODE (y))
4034 return 0;
4035
4036 /* For floating-point, consider everything unequal. This is a bit
4037 pessimistic, but this pass would only rarely do anything for FP
4038 anyway. */
4039 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4040 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_unsafe_math_optimizations)
4041 return 0;
4042
4043 /* For commutative operations, the RTX match if the operand match in any
4044 order. Also handle the simple binary and unary cases without a loop. */
4045 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4046 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4047 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4048 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4049 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4050 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4051 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4052 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4053 else if (GET_RTX_CLASS (code) == '1')
4054 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4055
4056 /* Handle special-cases first. */
4057 switch (code)
4058 {
4059 case REG:
4060 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4061 return 1;
4062
4063 /* If neither is user variable or hard register, check for possible
4064 equivalence. */
4065 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4066 || REGNO (x) < FIRST_PSEUDO_REGISTER
4067 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4068 return 0;
4069
4070 if (same_regs[REGNO (x)] == -1)
4071 {
4072 same_regs[REGNO (x)] = REGNO (y);
4073 num_same_regs++;
4074
4075 /* If this is the first time we are seeing a register on the `Y'
4076 side, see if it is the last use. If not, we can't thread the
4077 jump, so mark it as not equivalent. */
4078 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4079 return 0;
4080
4081 return 1;
4082 }
4083 else
4084 return (same_regs[REGNO (x)] == (int) REGNO (y));
4085
4086 break;
4087
4088 case MEM:
4089 /* If memory modified or either volatile, not equivalent.
4090 Else, check address. */
4091 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4092 return 0;
4093
4094 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4095
4096 case ASM_INPUT:
4097 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4098 return 0;
4099
4100 break;
4101
4102 case SET:
4103 /* Cancel a pending `same_regs' if setting equivalenced registers.
4104 Then process source. */
4105 if (GET_CODE (SET_DEST (x)) == REG
4106 && GET_CODE (SET_DEST (y)) == REG)
4107 {
4108 if (same_regs[REGNO (SET_DEST (x))] == (int) REGNO (SET_DEST (y)))
4109 {
4110 same_regs[REGNO (SET_DEST (x))] = -1;
4111 num_same_regs--;
4112 }
4113 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4114 return 0;
4115 }
4116 else
4117 {
4118 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4119 return 0;
4120 }
4121
4122 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4123
4124 case LABEL_REF:
4125 return XEXP (x, 0) == XEXP (y, 0);
4126
4127 case SYMBOL_REF:
4128 return XSTR (x, 0) == XSTR (y, 0);
4129
4130 default:
4131 break;
4132 }
4133
4134 if (x == y)
4135 return 1;
4136
4137 fmt = GET_RTX_FORMAT (code);
4138 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4139 {
4140 switch (fmt[i])
4141 {
4142 case 'w':
4143 if (XWINT (x, i) != XWINT (y, i))
4144 return 0;
4145 break;
4146
4147 case 'n':
4148 case 'i':
4149 if (XINT (x, i) != XINT (y, i))
4150 return 0;
4151 break;
4152
4153 case 'V':
4154 case 'E':
4155 /* Two vectors must have the same length. */
4156 if (XVECLEN (x, i) != XVECLEN (y, i))
4157 return 0;
4158
4159 /* And the corresponding elements must match. */
4160 for (j = 0; j < XVECLEN (x, i); j++)
4161 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4162 XVECEXP (y, i, j), yinsn) == 0)
4163 return 0;
4164 break;
4165
4166 case 'e':
4167 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4168 return 0;
4169 break;
4170
4171 case 'S':
4172 case 's':
4173 if (strcmp (XSTR (x, i), XSTR (y, i)))
4174 return 0;
4175 break;
4176
4177 case 'u':
4178 /* These are just backpointers, so they don't matter. */
4179 break;
4180
4181 case '0':
4182 case 't':
4183 break;
4184
4185 /* It is believed that rtx's at this level will never
4186 contain anything but integers and other rtx's,
4187 except for within LABEL_REFs and SYMBOL_REFs. */
4188 default:
4189 abort ();
4190 }
4191 }
4192 return 1;
4193 }