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jump.c: Include insn-attr.h.
[gcc.git] / gcc / jump.c
1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-98, 1999 Free Software Foundation, Inc.
3
4 This file is part of GNU CC.
5
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
20
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 "flags.h"
58 #include "hard-reg-set.h"
59 #include "regs.h"
60 #include "insn-config.h"
61 #include "insn-flags.h"
62 #include "insn-attr.h"
63 #include "recog.h"
64 #include "expr.h"
65 #include "real.h"
66 #include "except.h"
67 #include "toplev.h"
68
69 /* ??? Eventually must record somehow the labels used by jumps
70 from nested functions. */
71 /* Pre-record the next or previous real insn for each label?
72 No, this pass is very fast anyway. */
73 /* Condense consecutive labels?
74 This would make life analysis faster, maybe. */
75 /* Optimize jump y; x: ... y: jumpif... x?
76 Don't know if it is worth bothering with. */
77 /* Optimize two cases of conditional jump to conditional jump?
78 This can never delete any instruction or make anything dead,
79 or even change what is live at any point.
80 So perhaps let combiner do it. */
81
82 /* Vector indexed by uid.
83 For each CODE_LABEL, index by its uid to get first unconditional jump
84 that jumps to the label.
85 For each JUMP_INSN, index by its uid to get the next unconditional jump
86 that jumps to the same label.
87 Element 0 is the start of a chain of all return insns.
88 (It is safe to use element 0 because insn uid 0 is not used. */
89
90 static rtx *jump_chain;
91
92 /* List of labels referred to from initializers.
93 These can never be deleted. */
94 rtx forced_labels;
95
96 /* Maximum index in jump_chain. */
97
98 static int max_jump_chain;
99
100 /* Set nonzero by jump_optimize if control can fall through
101 to the end of the function. */
102 int can_reach_end;
103
104 /* Indicates whether death notes are significant in cross jump analysis.
105 Normally they are not significant, because of A and B jump to C,
106 and R dies in A, it must die in B. But this might not be true after
107 stack register conversion, and we must compare death notes in that
108 case. */
109
110 static int cross_jump_death_matters = 0;
111
112 static int init_label_info PROTO((rtx));
113 static void delete_barrier_successors PROTO((rtx));
114 static void mark_all_labels PROTO((rtx, int));
115 static rtx delete_unreferenced_labels PROTO((rtx));
116 static void delete_noop_moves PROTO((rtx));
117 static int calculate_can_reach_end PROTO((rtx, int, int));
118 static int duplicate_loop_exit_test PROTO((rtx));
119 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
120 static void do_cross_jump PROTO((rtx, rtx, rtx));
121 static int jump_back_p PROTO((rtx, rtx));
122 static int tension_vector_labels PROTO((rtx, int));
123 static void mark_jump_label PROTO((rtx, rtx, int));
124 static void delete_computation PROTO((rtx));
125 static void delete_from_jump_chain PROTO((rtx));
126 static int delete_labelref_insn PROTO((rtx, rtx, int));
127 static void mark_modified_reg PROTO((rtx, rtx));
128 static void redirect_tablejump PROTO((rtx, rtx));
129 #ifndef HAVE_cc0
130 static rtx find_insert_position PROTO((rtx, rtx));
131 #endif
132 \f
133 /* Delete no-op jumps and optimize jumps to jumps
134 and jumps around jumps.
135 Delete unused labels and unreachable code.
136
137 If CROSS_JUMP is 1, detect matching code
138 before a jump and its destination and unify them.
139 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
140
141 If NOOP_MOVES is nonzero, delete no-op move insns.
142
143 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
144 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
145
146 If `optimize' is zero, don't change any code,
147 just determine whether control drops off the end of the function.
148 This case occurs when we have -W and not -O.
149 It works because `delete_insn' checks the value of `optimize'
150 and refrains from actually deleting when that is 0. */
151
152 void
153 jump_optimize (f, cross_jump, noop_moves, after_regscan)
154 rtx f;
155 int cross_jump;
156 int noop_moves;
157 int after_regscan;
158 {
159 register rtx insn, next;
160 int changed;
161 int old_max_reg;
162 int first = 1;
163 int max_uid = 0;
164 rtx last_insn;
165
166 cross_jump_death_matters = (cross_jump == 2);
167 max_uid = init_label_info (f) + 1;
168
169 /* If we are performing cross jump optimizations, then initialize
170 tables mapping UIDs to EH regions to avoid incorrect movement
171 of insns from one EH region to another. */
172 if (flag_exceptions && cross_jump)
173 init_insn_eh_region (f, max_uid);
174
175 delete_barrier_successors (f);
176
177 /* Leave some extra room for labels and duplicate exit test insns
178 we make. */
179 max_jump_chain = max_uid * 14 / 10;
180 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
181 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
182
183 mark_all_labels (f, cross_jump);
184
185 /* Keep track of labels used from static data;
186 they cannot ever be deleted. */
187
188 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
189 LABEL_NUSES (XEXP (insn, 0))++;
190
191 check_exception_handler_labels ();
192
193 /* Keep track of labels used for marking handlers for exception
194 regions; they cannot usually be deleted. */
195
196 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
197 LABEL_NUSES (XEXP (insn, 0))++;
198
199 exception_optimize ();
200
201 last_insn = delete_unreferenced_labels (f);
202
203 if (!optimize)
204 {
205 can_reach_end = calculate_can_reach_end (last_insn, 1, 0);
206
207 /* Zero the "deleted" flag of all the "deleted" insns. */
208 for (insn = f; insn; insn = NEXT_INSN (insn))
209 INSN_DELETED_P (insn) = 0;
210
211 /* Show that the jump chain is not valid. */
212 jump_chain = 0;
213 return;
214 }
215
216 #ifdef HAVE_return
217 if (HAVE_return)
218 {
219 /* If we fall through to the epilogue, see if we can insert a RETURN insn
220 in front of it. If the machine allows it at this point (we might be
221 after reload for a leaf routine), it will improve optimization for it
222 to be there. */
223 insn = get_last_insn ();
224 while (insn && GET_CODE (insn) == NOTE)
225 insn = PREV_INSN (insn);
226
227 if (insn && GET_CODE (insn) != BARRIER)
228 {
229 emit_jump_insn (gen_return ());
230 emit_barrier ();
231 }
232 }
233 #endif
234
235 if (noop_moves)
236 delete_noop_moves (f);
237
238 /* If we haven't yet gotten to reload and we have just run regscan,
239 delete any insn that sets a register that isn't used elsewhere.
240 This helps some of the optimizations below by having less insns
241 being jumped around. */
242
243 if (! reload_completed && after_regscan)
244 for (insn = f; insn; insn = next)
245 {
246 rtx set = single_set (insn);
247
248 next = NEXT_INSN (insn);
249
250 if (set && GET_CODE (SET_DEST (set)) == REG
251 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
252 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
253 /* We use regno_last_note_uid so as not to delete the setting
254 of a reg that's used in notes. A subsequent optimization
255 might arrange to use that reg for real. */
256 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
257 && ! side_effects_p (SET_SRC (set))
258 && ! find_reg_note (insn, REG_RETVAL, 0))
259 delete_insn (insn);
260 }
261
262 /* Now iterate optimizing jumps until nothing changes over one pass. */
263 changed = 1;
264 old_max_reg = max_reg_num ();
265 while (changed)
266 {
267 changed = 0;
268
269 for (insn = f; insn; insn = next)
270 {
271 rtx reallabelprev;
272 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
273 rtx nlabel;
274 int this_is_simplejump, this_is_condjump, reversep = 0;
275 int this_is_condjump_in_parallel;
276
277 #if 0
278 /* If NOT the first iteration, if this is the last jump pass
279 (just before final), do the special peephole optimizations.
280 Avoiding the first iteration gives ordinary jump opts
281 a chance to work before peephole opts. */
282
283 if (reload_completed && !first && !flag_no_peephole)
284 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
285 peephole (insn);
286 #endif
287
288 /* That could have deleted some insns after INSN, so check now
289 what the following insn is. */
290
291 next = NEXT_INSN (insn);
292
293 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
294 jump. Try to optimize by duplicating the loop exit test if so.
295 This is only safe immediately after regscan, because it uses
296 the values of regno_first_uid and regno_last_uid. */
297 if (after_regscan && GET_CODE (insn) == NOTE
298 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
299 && (temp1 = next_nonnote_insn (insn)) != 0
300 && simplejump_p (temp1))
301 {
302 temp = PREV_INSN (insn);
303 if (duplicate_loop_exit_test (insn))
304 {
305 changed = 1;
306 next = NEXT_INSN (temp);
307 continue;
308 }
309 }
310
311 if (GET_CODE (insn) != JUMP_INSN)
312 continue;
313
314 this_is_simplejump = simplejump_p (insn);
315 this_is_condjump = condjump_p (insn);
316 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
317
318 /* Tension the labels in dispatch tables. */
319
320 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
321 changed |= tension_vector_labels (PATTERN (insn), 0);
322 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
323 changed |= tension_vector_labels (PATTERN (insn), 1);
324
325 /* If a dispatch table always goes to the same place,
326 get rid of it and replace the insn that uses it. */
327
328 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
329 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
330 {
331 int i;
332 rtx pat = PATTERN (insn);
333 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
334 int len = XVECLEN (pat, diff_vec_p);
335 rtx dispatch = prev_real_insn (insn);
336
337 for (i = 0; i < len; i++)
338 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
339 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
340 break;
341 if (i == len
342 && dispatch != 0
343 && GET_CODE (dispatch) == JUMP_INSN
344 && JUMP_LABEL (dispatch) != 0
345 /* Don't mess with a casesi insn. */
346 && !(GET_CODE (PATTERN (dispatch)) == SET
347 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
348 == IF_THEN_ELSE))
349 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
350 {
351 redirect_tablejump (dispatch,
352 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
353 changed = 1;
354 }
355 }
356
357 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
358
359 /* If a jump references the end of the function, try to turn
360 it into a RETURN insn, possibly a conditional one. */
361 if (JUMP_LABEL (insn)
362 && (next_active_insn (JUMP_LABEL (insn)) == 0
363 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
364 == RETURN))
365 changed |= redirect_jump (insn, NULL_RTX);
366
367 /* Detect jump to following insn. */
368 if (reallabelprev == insn && condjump_p (insn))
369 {
370 next = next_real_insn (JUMP_LABEL (insn));
371 delete_jump (insn);
372 changed = 1;
373 continue;
374 }
375
376 /* If we have an unconditional jump preceded by a USE, try to put
377 the USE before the target and jump there. This simplifies many
378 of the optimizations below since we don't have to worry about
379 dealing with these USE insns. We only do this if the label
380 being branch to already has the identical USE or if code
381 never falls through to that label. */
382
383 if (this_is_simplejump
384 && (temp = prev_nonnote_insn (insn)) != 0
385 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
386 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
387 && (GET_CODE (temp1) == BARRIER
388 || (GET_CODE (temp1) == INSN
389 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
390 /* Don't do this optimization if we have a loop containing only
391 the USE instruction, and the loop start label has a usage
392 count of 1. This is because we will redo this optimization
393 everytime through the outer loop, and jump opt will never
394 exit. */
395 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
396 && temp2 == JUMP_LABEL (insn)
397 && LABEL_NUSES (temp2) == 1))
398 {
399 if (GET_CODE (temp1) == BARRIER)
400 {
401 emit_insn_after (PATTERN (temp), temp1);
402 temp1 = NEXT_INSN (temp1);
403 }
404
405 delete_insn (temp);
406 redirect_jump (insn, get_label_before (temp1));
407 reallabelprev = prev_real_insn (temp1);
408 changed = 1;
409 }
410
411 /* Simplify if (...) x = a; else x = b; by converting it
412 to x = b; if (...) x = a;
413 if B is sufficiently simple, the test doesn't involve X,
414 and nothing in the test modifies B or X.
415
416 If we have small register classes, we also can't do this if X
417 is a hard register.
418
419 If the "x = b;" insn has any REG_NOTES, we don't do this because
420 of the possibility that we are running after CSE and there is a
421 REG_EQUAL note that is only valid if the branch has already been
422 taken. If we move the insn with the REG_EQUAL note, we may
423 fold the comparison to always be false in a later CSE pass.
424 (We could also delete the REG_NOTES when moving the insn, but it
425 seems simpler to not move it.) An exception is that we can move
426 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
427 value is the same as "b".
428
429 INSN is the branch over the `else' part.
430
431 We set:
432
433 TEMP to the jump insn preceding "x = a;"
434 TEMP1 to X
435 TEMP2 to the insn that sets "x = b;"
436 TEMP3 to the insn that sets "x = a;"
437 TEMP4 to the set of "x = b"; */
438
439 if (this_is_simplejump
440 && (temp3 = prev_active_insn (insn)) != 0
441 && GET_CODE (temp3) == INSN
442 && (temp4 = single_set (temp3)) != 0
443 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
444 && (! SMALL_REGISTER_CLASSES
445 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
446 && (temp2 = next_active_insn (insn)) != 0
447 && GET_CODE (temp2) == INSN
448 && (temp4 = single_set (temp2)) != 0
449 && rtx_equal_p (SET_DEST (temp4), temp1)
450 && ! side_effects_p (SET_SRC (temp4))
451 && ! may_trap_p (SET_SRC (temp4))
452 && (REG_NOTES (temp2) == 0
453 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
454 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
455 && XEXP (REG_NOTES (temp2), 1) == 0
456 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
457 SET_SRC (temp4))))
458 && (temp = prev_active_insn (temp3)) != 0
459 && condjump_p (temp) && ! simplejump_p (temp)
460 /* TEMP must skip over the "x = a;" insn */
461 && prev_real_insn (JUMP_LABEL (temp)) == insn
462 && no_labels_between_p (insn, JUMP_LABEL (temp))
463 /* There must be no other entries to the "x = b;" insn. */
464 && no_labels_between_p (JUMP_LABEL (temp), temp2)
465 /* INSN must either branch to the insn after TEMP2 or the insn
466 after TEMP2 must branch to the same place as INSN. */
467 && (reallabelprev == temp2
468 || ((temp5 = next_active_insn (temp2)) != 0
469 && simplejump_p (temp5)
470 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
471 {
472 /* The test expression, X, may be a complicated test with
473 multiple branches. See if we can find all the uses of
474 the label that TEMP branches to without hitting a CALL_INSN
475 or a jump to somewhere else. */
476 rtx target = JUMP_LABEL (temp);
477 int nuses = LABEL_NUSES (target);
478 rtx p;
479 #ifdef HAVE_cc0
480 rtx q;
481 #endif
482
483 /* Set P to the first jump insn that goes around "x = a;". */
484 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
485 {
486 if (GET_CODE (p) == JUMP_INSN)
487 {
488 if (condjump_p (p) && ! simplejump_p (p)
489 && JUMP_LABEL (p) == target)
490 {
491 nuses--;
492 if (nuses == 0)
493 break;
494 }
495 else
496 break;
497 }
498 else if (GET_CODE (p) == CALL_INSN)
499 break;
500 }
501
502 #ifdef HAVE_cc0
503 /* We cannot insert anything between a set of cc and its use
504 so if P uses cc0, we must back up to the previous insn. */
505 q = prev_nonnote_insn (p);
506 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
507 && sets_cc0_p (PATTERN (q)))
508 p = q;
509 #endif
510
511 if (p)
512 p = PREV_INSN (p);
513
514 /* If we found all the uses and there was no data conflict, we
515 can move the assignment unless we can branch into the middle
516 from somewhere. */
517 if (nuses == 0 && p
518 && no_labels_between_p (p, insn)
519 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
520 && ! reg_set_between_p (temp1, p, temp3)
521 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
522 || ! modified_between_p (SET_SRC (temp4), p, temp2))
523 /* Verify that registers used by the jump are not clobbered
524 by the instruction being moved. */
525 && ! regs_set_between_p (PATTERN (temp),
526 PREV_INSN (temp2),
527 NEXT_INSN (temp2)))
528 {
529 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
530 delete_insn (temp2);
531
532 /* Set NEXT to an insn that we know won't go away. */
533 next = next_active_insn (insn);
534
535 /* Delete the jump around the set. Note that we must do
536 this before we redirect the test jumps so that it won't
537 delete the code immediately following the assignment
538 we moved (which might be a jump). */
539
540 delete_insn (insn);
541
542 /* We either have two consecutive labels or a jump to
543 a jump, so adjust all the JUMP_INSNs to branch to where
544 INSN branches to. */
545 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
546 if (GET_CODE (p) == JUMP_INSN)
547 redirect_jump (p, target);
548
549 changed = 1;
550 continue;
551 }
552 }
553
554 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
555 to x = a; if (...) goto l; x = b;
556 if A is sufficiently simple, the test doesn't involve X,
557 and nothing in the test modifies A or X.
558
559 If we have small register classes, we also can't do this if X
560 is a hard register.
561
562 If the "x = a;" insn has any REG_NOTES, we don't do this because
563 of the possibility that we are running after CSE and there is a
564 REG_EQUAL note that is only valid if the branch has already been
565 taken. If we move the insn with the REG_EQUAL note, we may
566 fold the comparison to always be false in a later CSE pass.
567 (We could also delete the REG_NOTES when moving the insn, but it
568 seems simpler to not move it.) An exception is that we can move
569 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
570 value is the same as "a".
571
572 INSN is the goto.
573
574 We set:
575
576 TEMP to the jump insn preceding "x = a;"
577 TEMP1 to X
578 TEMP2 to the insn that sets "x = b;"
579 TEMP3 to the insn that sets "x = a;"
580 TEMP4 to the set of "x = a"; */
581
582 if (this_is_simplejump
583 && (temp2 = next_active_insn (insn)) != 0
584 && GET_CODE (temp2) == INSN
585 && (temp4 = single_set (temp2)) != 0
586 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
587 && (! SMALL_REGISTER_CLASSES
588 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
589 && (temp3 = prev_active_insn (insn)) != 0
590 && GET_CODE (temp3) == INSN
591 && (temp4 = single_set (temp3)) != 0
592 && rtx_equal_p (SET_DEST (temp4), temp1)
593 && ! side_effects_p (SET_SRC (temp4))
594 && ! may_trap_p (SET_SRC (temp4))
595 && (REG_NOTES (temp3) == 0
596 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
597 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
598 && XEXP (REG_NOTES (temp3), 1) == 0
599 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
600 SET_SRC (temp4))))
601 && (temp = prev_active_insn (temp3)) != 0
602 && condjump_p (temp) && ! simplejump_p (temp)
603 /* TEMP must skip over the "x = a;" insn */
604 && prev_real_insn (JUMP_LABEL (temp)) == insn
605 && no_labels_between_p (temp, insn))
606 {
607 rtx prev_label = JUMP_LABEL (temp);
608 rtx insert_after = prev_nonnote_insn (temp);
609
610 #ifdef HAVE_cc0
611 /* We cannot insert anything between a set of cc and its use. */
612 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
613 && sets_cc0_p (PATTERN (insert_after)))
614 insert_after = prev_nonnote_insn (insert_after);
615 #endif
616 ++LABEL_NUSES (prev_label);
617
618 if (insert_after
619 && no_labels_between_p (insert_after, temp)
620 && ! reg_referenced_between_p (temp1, insert_after, temp3)
621 && ! reg_referenced_between_p (temp1, temp3,
622 NEXT_INSN (temp2))
623 && ! reg_set_between_p (temp1, insert_after, temp)
624 && ! modified_between_p (SET_SRC (temp4), insert_after, temp)
625 /* Verify that registers used by the jump are not clobbered
626 by the instruction being moved. */
627 && ! regs_set_between_p (PATTERN (temp),
628 PREV_INSN (temp3),
629 NEXT_INSN (temp3))
630 && invert_jump (temp, JUMP_LABEL (insn)))
631 {
632 emit_insn_after_with_line_notes (PATTERN (temp3),
633 insert_after, temp3);
634 delete_insn (temp3);
635 delete_insn (insn);
636 /* Set NEXT to an insn that we know won't go away. */
637 next = temp2;
638 changed = 1;
639 }
640 if (prev_label && --LABEL_NUSES (prev_label) == 0)
641 delete_insn (prev_label);
642 if (changed)
643 continue;
644 }
645
646 #ifndef HAVE_cc0
647 /* If we have if (...) x = exp; and branches are expensive,
648 EXP is a single insn, does not have any side effects, cannot
649 trap, and is not too costly, convert this to
650 t = exp; if (...) x = t;
651
652 Don't do this when we have CC0 because it is unlikely to help
653 and we'd need to worry about where to place the new insn and
654 the potential for conflicts. We also can't do this when we have
655 notes on the insn for the same reason as above.
656
657 We set:
658
659 TEMP to the "x = exp;" insn.
660 TEMP1 to the single set in the "x = exp;" insn.
661 TEMP2 to "x". */
662
663 if (! reload_completed
664 && this_is_condjump && ! this_is_simplejump
665 && BRANCH_COST >= 3
666 && (temp = next_nonnote_insn (insn)) != 0
667 && GET_CODE (temp) == INSN
668 && REG_NOTES (temp) == 0
669 && (reallabelprev == temp
670 || ((temp2 = next_active_insn (temp)) != 0
671 && simplejump_p (temp2)
672 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
673 && (temp1 = single_set (temp)) != 0
674 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
675 && (! SMALL_REGISTER_CLASSES
676 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
677 && GET_CODE (SET_SRC (temp1)) != REG
678 && GET_CODE (SET_SRC (temp1)) != SUBREG
679 && GET_CODE (SET_SRC (temp1)) != CONST_INT
680 && ! side_effects_p (SET_SRC (temp1))
681 && ! may_trap_p (SET_SRC (temp1))
682 && rtx_cost (SET_SRC (temp1), SET) < 10)
683 {
684 rtx new = gen_reg_rtx (GET_MODE (temp2));
685
686 if ((temp3 = find_insert_position (insn, temp))
687 && validate_change (temp, &SET_DEST (temp1), new, 0))
688 {
689 next = emit_insn_after (gen_move_insn (temp2, new), insn);
690 emit_insn_after_with_line_notes (PATTERN (temp),
691 PREV_INSN (temp3), temp);
692 delete_insn (temp);
693 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
694
695 if (after_regscan)
696 {
697 reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
698 old_max_reg = max_reg_num ();
699 }
700 }
701 }
702
703 /* Similarly, if it takes two insns to compute EXP but they
704 have the same destination. Here TEMP3 will be the second
705 insn and TEMP4 the SET from that insn. */
706
707 if (! reload_completed
708 && this_is_condjump && ! this_is_simplejump
709 && BRANCH_COST >= 4
710 && (temp = next_nonnote_insn (insn)) != 0
711 && GET_CODE (temp) == INSN
712 && REG_NOTES (temp) == 0
713 && (temp3 = next_nonnote_insn (temp)) != 0
714 && GET_CODE (temp3) == INSN
715 && REG_NOTES (temp3) == 0
716 && (reallabelprev == temp3
717 || ((temp2 = next_active_insn (temp3)) != 0
718 && simplejump_p (temp2)
719 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
720 && (temp1 = single_set (temp)) != 0
721 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
722 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
723 && (! SMALL_REGISTER_CLASSES
724 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
725 && ! side_effects_p (SET_SRC (temp1))
726 && ! may_trap_p (SET_SRC (temp1))
727 && rtx_cost (SET_SRC (temp1), SET) < 10
728 && (temp4 = single_set (temp3)) != 0
729 && rtx_equal_p (SET_DEST (temp4), temp2)
730 && ! side_effects_p (SET_SRC (temp4))
731 && ! may_trap_p (SET_SRC (temp4))
732 && rtx_cost (SET_SRC (temp4), SET) < 10)
733 {
734 rtx new = gen_reg_rtx (GET_MODE (temp2));
735
736 if ((temp5 = find_insert_position (insn, temp))
737 && (temp6 = find_insert_position (insn, temp3))
738 && validate_change (temp, &SET_DEST (temp1), new, 0))
739 {
740 /* Use the earliest of temp5 and temp6. */
741 if (temp5 != insn)
742 temp6 = temp5;
743 next = emit_insn_after (gen_move_insn (temp2, new), insn);
744 emit_insn_after_with_line_notes (PATTERN (temp),
745 PREV_INSN (temp6), temp);
746 emit_insn_after_with_line_notes
747 (replace_rtx (PATTERN (temp3), temp2, new),
748 PREV_INSN (temp6), temp3);
749 delete_insn (temp);
750 delete_insn (temp3);
751 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
752
753 if (after_regscan)
754 {
755 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
756 old_max_reg = max_reg_num ();
757 }
758 }
759 }
760
761 /* Finally, handle the case where two insns are used to
762 compute EXP but a temporary register is used. Here we must
763 ensure that the temporary register is not used anywhere else. */
764
765 if (! reload_completed
766 && after_regscan
767 && this_is_condjump && ! this_is_simplejump
768 && BRANCH_COST >= 4
769 && (temp = next_nonnote_insn (insn)) != 0
770 && GET_CODE (temp) == INSN
771 && REG_NOTES (temp) == 0
772 && (temp3 = next_nonnote_insn (temp)) != 0
773 && GET_CODE (temp3) == INSN
774 && REG_NOTES (temp3) == 0
775 && (reallabelprev == temp3
776 || ((temp2 = next_active_insn (temp3)) != 0
777 && simplejump_p (temp2)
778 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
779 && (temp1 = single_set (temp)) != 0
780 && (temp5 = SET_DEST (temp1),
781 (GET_CODE (temp5) == REG
782 || (GET_CODE (temp5) == SUBREG
783 && (temp5 = SUBREG_REG (temp5),
784 GET_CODE (temp5) == REG))))
785 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
786 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
787 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
788 && ! side_effects_p (SET_SRC (temp1))
789 && ! may_trap_p (SET_SRC (temp1))
790 && rtx_cost (SET_SRC (temp1), SET) < 10
791 && (temp4 = single_set (temp3)) != 0
792 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
793 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
794 && (! SMALL_REGISTER_CLASSES
795 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
796 && rtx_equal_p (SET_DEST (temp4), temp2)
797 && ! side_effects_p (SET_SRC (temp4))
798 && ! may_trap_p (SET_SRC (temp4))
799 && rtx_cost (SET_SRC (temp4), SET) < 10)
800 {
801 rtx new = gen_reg_rtx (GET_MODE (temp2));
802
803 if ((temp5 = find_insert_position (insn, temp))
804 && (temp6 = find_insert_position (insn, temp3))
805 && validate_change (temp3, &SET_DEST (temp4), new, 0))
806 {
807 /* Use the earliest of temp5 and temp6. */
808 if (temp5 != insn)
809 temp6 = temp5;
810 next = emit_insn_after (gen_move_insn (temp2, new), insn);
811 emit_insn_after_with_line_notes (PATTERN (temp),
812 PREV_INSN (temp6), temp);
813 emit_insn_after_with_line_notes (PATTERN (temp3),
814 PREV_INSN (temp6), temp3);
815 delete_insn (temp);
816 delete_insn (temp3);
817 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
818
819 if (after_regscan)
820 {
821 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
822 old_max_reg = max_reg_num ();
823 }
824 }
825 }
826 #endif /* HAVE_cc0 */
827
828 /* Try to use a conditional move (if the target has them), or a
829 store-flag insn. The general case is:
830
831 1) x = a; if (...) x = b; and
832 2) if (...) x = b;
833
834 If the jump would be faster, the machine should not have defined
835 the movcc or scc insns!. These cases are often made by the
836 previous optimization.
837
838 The second case is treated as x = x; if (...) x = b;.
839
840 INSN here is the jump around the store. We set:
841
842 TEMP to the "x = b;" insn.
843 TEMP1 to X.
844 TEMP2 to B.
845 TEMP3 to A (X in the second case).
846 TEMP4 to the condition being tested.
847 TEMP5 to the earliest insn used to find the condition. */
848
849 if (/* We can't do this after reload has completed. */
850 ! reload_completed
851 && this_is_condjump && ! this_is_simplejump
852 /* Set TEMP to the "x = b;" insn. */
853 && (temp = next_nonnote_insn (insn)) != 0
854 && GET_CODE (temp) == INSN
855 && GET_CODE (PATTERN (temp)) == SET
856 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
857 && (! SMALL_REGISTER_CLASSES
858 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
859 && ! side_effects_p (temp2 = SET_SRC (PATTERN (temp)))
860 && ! may_trap_p (temp2)
861 /* Allow either form, but prefer the former if both apply.
862 There is no point in using the old value of TEMP1 if
863 it is a register, since cse will alias them. It can
864 lose if the old value were a hard register since CSE
865 won't replace hard registers. Avoid using TEMP3 if
866 small register classes and it is a hard register. */
867 && (((temp3 = reg_set_last (temp1, insn)) != 0
868 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
869 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
870 /* Make the latter case look like x = x; if (...) x = b; */
871 || (temp3 = temp1, 1))
872 /* INSN must either branch to the insn after TEMP or the insn
873 after TEMP must branch to the same place as INSN. */
874 && (reallabelprev == temp
875 || ((temp4 = next_active_insn (temp)) != 0
876 && simplejump_p (temp4)
877 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
878 && (temp4 = get_condition (insn, &temp5)) != 0
879 /* We must be comparing objects whose modes imply the size.
880 We could handle BLKmode if (1) emit_store_flag could
881 and (2) we could find the size reliably. */
882 && GET_MODE (XEXP (temp4, 0)) != BLKmode
883 /* Even if branches are cheap, the store_flag optimization
884 can win when the operation to be performed can be
885 expressed directly. */
886 #ifdef HAVE_cc0
887 /* If the previous insn sets CC0 and something else, we can't
888 do this since we are going to delete that insn. */
889
890 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
891 && GET_CODE (temp6) == INSN
892 && (sets_cc0_p (PATTERN (temp6)) == -1
893 || (sets_cc0_p (PATTERN (temp6)) == 1
894 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
895 #endif
896 )
897 {
898 #ifdef HAVE_conditional_move
899 /* First try a conditional move. */
900 {
901 enum rtx_code code = GET_CODE (temp4);
902 rtx var = temp1;
903 rtx cond0, cond1, aval, bval;
904 rtx target;
905
906 /* Copy the compared variables into cond0 and cond1, so that
907 any side effects performed in or after the old comparison,
908 will not affect our compare which will come later. */
909 /* ??? Is it possible to just use the comparison in the jump
910 insn? After all, we're going to delete it. We'd have
911 to modify emit_conditional_move to take a comparison rtx
912 instead or write a new function. */
913 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
914 /* We want the target to be able to simplify comparisons with
915 zero (and maybe other constants as well), so don't create
916 pseudos for them. There's no need to either. */
917 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
918 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
919 cond1 = XEXP (temp4, 1);
920 else
921 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
922
923 aval = temp3;
924 bval = temp2;
925
926 start_sequence ();
927 target = emit_conditional_move (var, code,
928 cond0, cond1, VOIDmode,
929 aval, bval, GET_MODE (var),
930 (code == LTU || code == GEU
931 || code == LEU || code == GTU));
932
933 if (target)
934 {
935 rtx seq1,seq2,last;
936
937 /* Save the conditional move sequence but don't emit it
938 yet. On some machines, like the alpha, it is possible
939 that temp5 == insn, so next generate the sequence that
940 saves the compared values and then emit both
941 sequences ensuring seq1 occurs before seq2. */
942 seq2 = get_insns ();
943 end_sequence ();
944
945 /* Now that we can't fail, generate the copy insns that
946 preserve the compared values. */
947 start_sequence ();
948 emit_move_insn (cond0, XEXP (temp4, 0));
949 if (cond1 != XEXP (temp4, 1))
950 emit_move_insn (cond1, XEXP (temp4, 1));
951 seq1 = get_insns ();
952 end_sequence ();
953
954 emit_insns_before (seq1, temp5);
955 /* Insert conditional move after insn, to be sure that
956 the jump and a possible compare won't be separated */
957 last = emit_insns_after (seq2, insn);
958
959 /* ??? We can also delete the insn that sets X to A.
960 Flow will do it too though. */
961 delete_insn (temp);
962 next = NEXT_INSN (insn);
963 delete_jump (insn);
964
965 if (after_regscan)
966 {
967 reg_scan_update (seq1, NEXT_INSN (last), old_max_reg);
968 old_max_reg = max_reg_num ();
969 }
970
971 changed = 1;
972 continue;
973 }
974 else
975 end_sequence ();
976 }
977 #endif
978
979 /* That didn't work, try a store-flag insn.
980
981 We further divide the cases into:
982
983 1) x = a; if (...) x = b; and either A or B is zero,
984 2) if (...) x = 0; and jumps are expensive,
985 3) x = a; if (...) x = b; and A and B are constants where all
986 the set bits in A are also set in B and jumps are expensive,
987 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
988 more expensive, and
989 5) if (...) x = b; if jumps are even more expensive. */
990
991 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
992 && ((GET_CODE (temp3) == CONST_INT)
993 /* Make the latter case look like
994 x = x; if (...) x = 0; */
995 || (temp3 = temp1,
996 ((BRANCH_COST >= 2
997 && temp2 == const0_rtx)
998 || BRANCH_COST >= 3)))
999 /* If B is zero, OK; if A is zero, can only do (1) if we
1000 can reverse the condition. See if (3) applies possibly
1001 by reversing the condition. Prefer reversing to (4) when
1002 branches are very expensive. */
1003 && (((BRANCH_COST >= 2
1004 || STORE_FLAG_VALUE == -1
1005 || (STORE_FLAG_VALUE == 1
1006 /* Check that the mask is a power of two,
1007 so that it can probably be generated
1008 with a shift. */
1009 && GET_CODE (temp3) == CONST_INT
1010 && exact_log2 (INTVAL (temp3)) >= 0))
1011 && (reversep = 0, temp2 == const0_rtx))
1012 || ((BRANCH_COST >= 2
1013 || STORE_FLAG_VALUE == -1
1014 || (STORE_FLAG_VALUE == 1
1015 && GET_CODE (temp2) == CONST_INT
1016 && exact_log2 (INTVAL (temp2)) >= 0))
1017 && temp3 == const0_rtx
1018 && (reversep = can_reverse_comparison_p (temp4, insn)))
1019 || (BRANCH_COST >= 2
1020 && GET_CODE (temp2) == CONST_INT
1021 && GET_CODE (temp3) == CONST_INT
1022 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1023 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1024 && (reversep = can_reverse_comparison_p (temp4,
1025 insn)))))
1026 || BRANCH_COST >= 3)
1027 )
1028 {
1029 enum rtx_code code = GET_CODE (temp4);
1030 rtx uval, cval, var = temp1;
1031 int normalizep;
1032 rtx target;
1033
1034 /* If necessary, reverse the condition. */
1035 if (reversep)
1036 code = reverse_condition (code), uval = temp2, cval = temp3;
1037 else
1038 uval = temp3, cval = temp2;
1039
1040 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1041 is the constant 1, it is best to just compute the result
1042 directly. If UVAL is constant and STORE_FLAG_VALUE
1043 includes all of its bits, it is best to compute the flag
1044 value unnormalized and `and' it with UVAL. Otherwise,
1045 normalize to -1 and `and' with UVAL. */
1046 normalizep = (cval != const0_rtx ? -1
1047 : (uval == const1_rtx ? 1
1048 : (GET_CODE (uval) == CONST_INT
1049 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1050 ? 0 : -1));
1051
1052 /* We will be putting the store-flag insn immediately in
1053 front of the comparison that was originally being done,
1054 so we know all the variables in TEMP4 will be valid.
1055 However, this might be in front of the assignment of
1056 A to VAR. If it is, it would clobber the store-flag
1057 we will be emitting.
1058
1059 Therefore, emit into a temporary which will be copied to
1060 VAR immediately after TEMP. */
1061
1062 start_sequence ();
1063 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1064 XEXP (temp4, 0), XEXP (temp4, 1),
1065 VOIDmode,
1066 (code == LTU || code == LEU
1067 || code == GEU || code == GTU),
1068 normalizep);
1069 if (target)
1070 {
1071 rtx seq;
1072 rtx before = insn;
1073
1074 seq = get_insns ();
1075 end_sequence ();
1076
1077 /* Put the store-flag insns in front of the first insn
1078 used to compute the condition to ensure that we
1079 use the same values of them as the current
1080 comparison. However, the remainder of the insns we
1081 generate will be placed directly in front of the
1082 jump insn, in case any of the pseudos we use
1083 are modified earlier. */
1084
1085 emit_insns_before (seq, temp5);
1086
1087 start_sequence ();
1088
1089 /* Both CVAL and UVAL are non-zero. */
1090 if (cval != const0_rtx && uval != const0_rtx)
1091 {
1092 rtx tem1, tem2;
1093
1094 tem1 = expand_and (uval, target, NULL_RTX);
1095 if (GET_CODE (cval) == CONST_INT
1096 && GET_CODE (uval) == CONST_INT
1097 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1098 tem2 = cval;
1099 else
1100 {
1101 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1102 target, NULL_RTX, 0);
1103 tem2 = expand_and (cval, tem2,
1104 (GET_CODE (tem2) == REG
1105 ? tem2 : 0));
1106 }
1107
1108 /* If we usually make new pseudos, do so here. This
1109 turns out to help machines that have conditional
1110 move insns. */
1111 /* ??? Conditional moves have already been handled.
1112 This may be obsolete. */
1113
1114 if (flag_expensive_optimizations)
1115 target = 0;
1116
1117 target = expand_binop (GET_MODE (var), ior_optab,
1118 tem1, tem2, target,
1119 1, OPTAB_WIDEN);
1120 }
1121 else if (normalizep != 1)
1122 {
1123 /* We know that either CVAL or UVAL is zero. If
1124 UVAL is zero, negate TARGET and `and' with CVAL.
1125 Otherwise, `and' with UVAL. */
1126 if (uval == const0_rtx)
1127 {
1128 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1129 target, NULL_RTX, 0);
1130 uval = cval;
1131 }
1132
1133 target = expand_and (uval, target,
1134 (GET_CODE (target) == REG
1135 && ! preserve_subexpressions_p ()
1136 ? target : NULL_RTX));
1137 }
1138
1139 emit_move_insn (var, target);
1140 seq = get_insns ();
1141 end_sequence ();
1142 #ifdef HAVE_cc0
1143 /* If INSN uses CC0, we must not separate it from the
1144 insn that sets cc0. */
1145 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1146 before = prev_nonnote_insn (before);
1147 #endif
1148 emit_insns_before (seq, before);
1149
1150 delete_insn (temp);
1151 next = NEXT_INSN (insn);
1152 delete_jump (insn);
1153
1154 if (after_regscan)
1155 {
1156 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1157 old_max_reg = max_reg_num ();
1158 }
1159
1160 changed = 1;
1161 continue;
1162 }
1163 else
1164 end_sequence ();
1165 }
1166 }
1167
1168 /* If branches are expensive, convert
1169 if (foo) bar++; to bar += (foo != 0);
1170 and similarly for "bar--;"
1171
1172 INSN is the conditional branch around the arithmetic. We set:
1173
1174 TEMP is the arithmetic insn.
1175 TEMP1 is the SET doing the arithmetic.
1176 TEMP2 is the operand being incremented or decremented.
1177 TEMP3 to the condition being tested.
1178 TEMP4 to the earliest insn used to find the condition. */
1179
1180 if ((BRANCH_COST >= 2
1181 #ifdef HAVE_incscc
1182 || HAVE_incscc
1183 #endif
1184 #ifdef HAVE_decscc
1185 || HAVE_decscc
1186 #endif
1187 )
1188 && ! reload_completed
1189 && this_is_condjump && ! this_is_simplejump
1190 && (temp = next_nonnote_insn (insn)) != 0
1191 && (temp1 = single_set (temp)) != 0
1192 && (temp2 = SET_DEST (temp1),
1193 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1194 && GET_CODE (SET_SRC (temp1)) == PLUS
1195 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1196 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1197 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1198 && ! side_effects_p (temp2)
1199 && ! may_trap_p (temp2)
1200 /* INSN must either branch to the insn after TEMP or the insn
1201 after TEMP must branch to the same place as INSN. */
1202 && (reallabelprev == temp
1203 || ((temp3 = next_active_insn (temp)) != 0
1204 && simplejump_p (temp3)
1205 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1206 && (temp3 = get_condition (insn, &temp4)) != 0
1207 /* We must be comparing objects whose modes imply the size.
1208 We could handle BLKmode if (1) emit_store_flag could
1209 and (2) we could find the size reliably. */
1210 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1211 && can_reverse_comparison_p (temp3, insn))
1212 {
1213 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1214 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1215
1216 start_sequence ();
1217
1218 /* It must be the case that TEMP2 is not modified in the range
1219 [TEMP4, INSN). The one exception we make is if the insn
1220 before INSN sets TEMP2 to something which is also unchanged
1221 in that range. In that case, we can move the initialization
1222 into our sequence. */
1223
1224 if ((temp5 = prev_active_insn (insn)) != 0
1225 && no_labels_between_p (temp5, insn)
1226 && GET_CODE (temp5) == INSN
1227 && (temp6 = single_set (temp5)) != 0
1228 && rtx_equal_p (temp2, SET_DEST (temp6))
1229 && (CONSTANT_P (SET_SRC (temp6))
1230 || GET_CODE (SET_SRC (temp6)) == REG
1231 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1232 {
1233 emit_insn (PATTERN (temp5));
1234 init_insn = temp5;
1235 init = SET_SRC (temp6);
1236 }
1237
1238 if (CONSTANT_P (init)
1239 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1240 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1241 XEXP (temp3, 0), XEXP (temp3, 1),
1242 VOIDmode,
1243 (code == LTU || code == LEU
1244 || code == GTU || code == GEU), 1);
1245
1246 /* If we can do the store-flag, do the addition or
1247 subtraction. */
1248
1249 if (target)
1250 target = expand_binop (GET_MODE (temp2),
1251 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1252 ? add_optab : sub_optab),
1253 temp2, target, temp2, 0, OPTAB_WIDEN);
1254
1255 if (target != 0)
1256 {
1257 /* Put the result back in temp2 in case it isn't already.
1258 Then replace the jump, possible a CC0-setting insn in
1259 front of the jump, and TEMP, with the sequence we have
1260 made. */
1261
1262 if (target != temp2)
1263 emit_move_insn (temp2, target);
1264
1265 seq = get_insns ();
1266 end_sequence ();
1267
1268 emit_insns_before (seq, temp4);
1269 delete_insn (temp);
1270
1271 if (init_insn)
1272 delete_insn (init_insn);
1273
1274 next = NEXT_INSN (insn);
1275 #ifdef HAVE_cc0
1276 delete_insn (prev_nonnote_insn (insn));
1277 #endif
1278 delete_insn (insn);
1279
1280 if (after_regscan)
1281 {
1282 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1283 old_max_reg = max_reg_num ();
1284 }
1285
1286 changed = 1;
1287 continue;
1288 }
1289 else
1290 end_sequence ();
1291 }
1292
1293 /* Simplify if (...) x = 1; else {...} if (x) ...
1294 We recognize this case scanning backwards as well.
1295
1296 TEMP is the assignment to x;
1297 TEMP1 is the label at the head of the second if. */
1298 /* ?? This should call get_condition to find the values being
1299 compared, instead of looking for a COMPARE insn when HAVE_cc0
1300 is not defined. This would allow it to work on the m88k. */
1301 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1302 is not defined and the condition is tested by a separate compare
1303 insn. This is because the code below assumes that the result
1304 of the compare dies in the following branch.
1305
1306 Not only that, but there might be other insns between the
1307 compare and branch whose results are live. Those insns need
1308 to be executed.
1309
1310 A way to fix this is to move the insns at JUMP_LABEL (insn)
1311 to before INSN. If we are running before flow, they will
1312 be deleted if they aren't needed. But this doesn't work
1313 well after flow.
1314
1315 This is really a special-case of jump threading, anyway. The
1316 right thing to do is to replace this and jump threading with
1317 much simpler code in cse.
1318
1319 This code has been turned off in the non-cc0 case in the
1320 meantime. */
1321
1322 #ifdef HAVE_cc0
1323 else if (this_is_simplejump
1324 /* Safe to skip USE and CLOBBER insns here
1325 since they will not be deleted. */
1326 && (temp = prev_active_insn (insn))
1327 && no_labels_between_p (temp, insn)
1328 && GET_CODE (temp) == INSN
1329 && GET_CODE (PATTERN (temp)) == SET
1330 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1331 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1332 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1333 /* If we find that the next value tested is `x'
1334 (TEMP1 is the insn where this happens), win. */
1335 && GET_CODE (temp1) == INSN
1336 && GET_CODE (PATTERN (temp1)) == SET
1337 #ifdef HAVE_cc0
1338 /* Does temp1 `tst' the value of x? */
1339 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1340 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1341 && (temp1 = next_nonnote_insn (temp1))
1342 #else
1343 /* Does temp1 compare the value of x against zero? */
1344 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1345 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1346 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1347 == SET_DEST (PATTERN (temp)))
1348 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1349 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1350 #endif
1351 && condjump_p (temp1))
1352 {
1353 /* Get the if_then_else from the condjump. */
1354 rtx choice = SET_SRC (PATTERN (temp1));
1355 if (GET_CODE (choice) == IF_THEN_ELSE)
1356 {
1357 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1358 rtx val = SET_SRC (PATTERN (temp));
1359 rtx cond
1360 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1361 val, const0_rtx);
1362 rtx ultimate;
1363
1364 if (cond == const_true_rtx)
1365 ultimate = XEXP (choice, 1);
1366 else if (cond == const0_rtx)
1367 ultimate = XEXP (choice, 2);
1368 else
1369 ultimate = 0;
1370
1371 if (ultimate == pc_rtx)
1372 ultimate = get_label_after (temp1);
1373 else if (ultimate && GET_CODE (ultimate) != RETURN)
1374 ultimate = XEXP (ultimate, 0);
1375
1376 if (ultimate && JUMP_LABEL(insn) != ultimate)
1377 changed |= redirect_jump (insn, ultimate);
1378 }
1379 }
1380 #endif
1381
1382 #if 0
1383 /* @@ This needs a bit of work before it will be right.
1384
1385 Any type of comparison can be accepted for the first and
1386 second compare. When rewriting the first jump, we must
1387 compute the what conditions can reach label3, and use the
1388 appropriate code. We can not simply reverse/swap the code
1389 of the first jump. In some cases, the second jump must be
1390 rewritten also.
1391
1392 For example,
1393 < == converts to > ==
1394 < != converts to == >
1395 etc.
1396
1397 If the code is written to only accept an '==' test for the second
1398 compare, then all that needs to be done is to swap the condition
1399 of the first branch.
1400
1401 It is questionable whether we want this optimization anyways,
1402 since if the user wrote code like this because he/she knew that
1403 the jump to label1 is taken most of the time, then rewriting
1404 this gives slower code. */
1405 /* @@ This should call get_condition to find the values being
1406 compared, instead of looking for a COMPARE insn when HAVE_cc0
1407 is not defined. This would allow it to work on the m88k. */
1408 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1409 is not defined and the condition is tested by a separate compare
1410 insn. This is because the code below assumes that the result
1411 of the compare dies in the following branch. */
1412
1413 /* Simplify test a ~= b
1414 condjump label1;
1415 test a == b
1416 condjump label2;
1417 jump label3;
1418 label1:
1419
1420 rewriting as
1421 test a ~~= b
1422 condjump label3
1423 test a == b
1424 condjump label2
1425 label1:
1426
1427 where ~= is an inequality, e.g. >, and ~~= is the swapped
1428 inequality, e.g. <.
1429
1430 We recognize this case scanning backwards.
1431
1432 TEMP is the conditional jump to `label2';
1433 TEMP1 is the test for `a == b';
1434 TEMP2 is the conditional jump to `label1';
1435 TEMP3 is the test for `a ~= b'. */
1436 else if (this_is_simplejump
1437 && (temp = prev_active_insn (insn))
1438 && no_labels_between_p (temp, insn)
1439 && condjump_p (temp)
1440 && (temp1 = prev_active_insn (temp))
1441 && no_labels_between_p (temp1, temp)
1442 && GET_CODE (temp1) == INSN
1443 && GET_CODE (PATTERN (temp1)) == SET
1444 #ifdef HAVE_cc0
1445 && sets_cc0_p (PATTERN (temp1)) == 1
1446 #else
1447 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1448 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1449 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1450 #endif
1451 && (temp2 = prev_active_insn (temp1))
1452 && no_labels_between_p (temp2, temp1)
1453 && condjump_p (temp2)
1454 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1455 && (temp3 = prev_active_insn (temp2))
1456 && no_labels_between_p (temp3, temp2)
1457 && GET_CODE (PATTERN (temp3)) == SET
1458 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1459 SET_DEST (PATTERN (temp1)))
1460 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1461 SET_SRC (PATTERN (temp3)))
1462 && ! inequality_comparisons_p (PATTERN (temp))
1463 && inequality_comparisons_p (PATTERN (temp2)))
1464 {
1465 rtx fallthrough_label = JUMP_LABEL (temp2);
1466
1467 ++LABEL_NUSES (fallthrough_label);
1468 if (swap_jump (temp2, JUMP_LABEL (insn)))
1469 {
1470 delete_insn (insn);
1471 changed = 1;
1472 }
1473
1474 if (--LABEL_NUSES (fallthrough_label) == 0)
1475 delete_insn (fallthrough_label);
1476 }
1477 #endif
1478 /* Simplify if (...) {... x = 1;} if (x) ...
1479
1480 We recognize this case backwards.
1481
1482 TEMP is the test of `x';
1483 TEMP1 is the assignment to `x' at the end of the
1484 previous statement. */
1485 /* @@ This should call get_condition to find the values being
1486 compared, instead of looking for a COMPARE insn when HAVE_cc0
1487 is not defined. This would allow it to work on the m88k. */
1488 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1489 is not defined and the condition is tested by a separate compare
1490 insn. This is because the code below assumes that the result
1491 of the compare dies in the following branch. */
1492
1493 /* ??? This has to be turned off. The problem is that the
1494 unconditional jump might indirectly end up branching to the
1495 label between TEMP1 and TEMP. We can't detect this, in general,
1496 since it may become a jump to there after further optimizations.
1497 If that jump is done, it will be deleted, so we will retry
1498 this optimization in the next pass, thus an infinite loop.
1499
1500 The present code prevents this by putting the jump after the
1501 label, but this is not logically correct. */
1502 #if 0
1503 else if (this_is_condjump
1504 /* Safe to skip USE and CLOBBER insns here
1505 since they will not be deleted. */
1506 && (temp = prev_active_insn (insn))
1507 && no_labels_between_p (temp, insn)
1508 && GET_CODE (temp) == INSN
1509 && GET_CODE (PATTERN (temp)) == SET
1510 #ifdef HAVE_cc0
1511 && sets_cc0_p (PATTERN (temp)) == 1
1512 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1513 #else
1514 /* Temp must be a compare insn, we can not accept a register
1515 to register move here, since it may not be simply a
1516 tst insn. */
1517 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1518 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1519 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1520 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1521 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1522 #endif
1523 /* May skip USE or CLOBBER insns here
1524 for checking for opportunity, since we
1525 take care of them later. */
1526 && (temp1 = prev_active_insn (temp))
1527 && GET_CODE (temp1) == INSN
1528 && GET_CODE (PATTERN (temp1)) == SET
1529 #ifdef HAVE_cc0
1530 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1531 #else
1532 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1533 == SET_DEST (PATTERN (temp1)))
1534 #endif
1535 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1536 /* If this isn't true, cse will do the job. */
1537 && ! no_labels_between_p (temp1, temp))
1538 {
1539 /* Get the if_then_else from the condjump. */
1540 rtx choice = SET_SRC (PATTERN (insn));
1541 if (GET_CODE (choice) == IF_THEN_ELSE
1542 && (GET_CODE (XEXP (choice, 0)) == EQ
1543 || GET_CODE (XEXP (choice, 0)) == NE))
1544 {
1545 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1546 rtx last_insn;
1547 rtx ultimate;
1548 rtx p;
1549
1550 /* Get the place that condjump will jump to
1551 if it is reached from here. */
1552 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1553 == want_nonzero)
1554 ultimate = XEXP (choice, 1);
1555 else
1556 ultimate = XEXP (choice, 2);
1557 /* Get it as a CODE_LABEL. */
1558 if (ultimate == pc_rtx)
1559 ultimate = get_label_after (insn);
1560 else
1561 /* Get the label out of the LABEL_REF. */
1562 ultimate = XEXP (ultimate, 0);
1563
1564 /* Insert the jump immediately before TEMP, specifically
1565 after the label that is between TEMP1 and TEMP. */
1566 last_insn = PREV_INSN (temp);
1567
1568 /* If we would be branching to the next insn, the jump
1569 would immediately be deleted and the re-inserted in
1570 a subsequent pass over the code. So don't do anything
1571 in that case. */
1572 if (next_active_insn (last_insn)
1573 != next_active_insn (ultimate))
1574 {
1575 emit_barrier_after (last_insn);
1576 p = emit_jump_insn_after (gen_jump (ultimate),
1577 last_insn);
1578 JUMP_LABEL (p) = ultimate;
1579 ++LABEL_NUSES (ultimate);
1580 if (INSN_UID (ultimate) < max_jump_chain
1581 && INSN_CODE (p) < max_jump_chain)
1582 {
1583 jump_chain[INSN_UID (p)]
1584 = jump_chain[INSN_UID (ultimate)];
1585 jump_chain[INSN_UID (ultimate)] = p;
1586 }
1587 changed = 1;
1588 continue;
1589 }
1590 }
1591 }
1592 #endif
1593 /* Detect a conditional jump going to the same place
1594 as an immediately following unconditional jump. */
1595 else if (this_is_condjump
1596 && (temp = next_active_insn (insn)) != 0
1597 && simplejump_p (temp)
1598 && (next_active_insn (JUMP_LABEL (insn))
1599 == next_active_insn (JUMP_LABEL (temp))))
1600 {
1601 rtx tem = temp;
1602
1603 /* ??? Optional. Disables some optimizations, but makes
1604 gcov output more accurate with -O. */
1605 if (flag_test_coverage && !reload_completed)
1606 for (tem = insn; tem != temp; tem = NEXT_INSN (tem))
1607 if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0)
1608 break;
1609
1610 if (tem == temp)
1611 {
1612 delete_jump (insn);
1613 changed = 1;
1614 continue;
1615 }
1616 }
1617 #ifdef HAVE_trap
1618 /* Detect a conditional jump jumping over an unconditional trap. */
1619 else if (HAVE_trap
1620 && this_is_condjump && ! this_is_simplejump
1621 && reallabelprev != 0
1622 && GET_CODE (reallabelprev) == INSN
1623 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
1624 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
1625 && prev_active_insn (reallabelprev) == insn
1626 && no_labels_between_p (insn, reallabelprev)
1627 && (temp2 = get_condition (insn, &temp4))
1628 && can_reverse_comparison_p (temp2, insn))
1629 {
1630 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
1631 XEXP (temp2, 0), XEXP (temp2, 1),
1632 TRAP_CODE (PATTERN (reallabelprev)));
1633
1634 if (new)
1635 {
1636 emit_insn_before (new, temp4);
1637 delete_insn (reallabelprev);
1638 delete_jump (insn);
1639 changed = 1;
1640 continue;
1641 }
1642 }
1643 /* Detect a jump jumping to an unconditional trap. */
1644 else if (HAVE_trap && this_is_condjump
1645 && (temp = next_active_insn (JUMP_LABEL (insn)))
1646 && GET_CODE (temp) == INSN
1647 && GET_CODE (PATTERN (temp)) == TRAP_IF
1648 && (this_is_simplejump
1649 || (temp2 = get_condition (insn, &temp4))))
1650 {
1651 rtx tc = TRAP_CONDITION (PATTERN (temp));
1652
1653 if (tc == const_true_rtx
1654 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
1655 {
1656 rtx new;
1657 /* Replace an unconditional jump to a trap with a trap. */
1658 if (this_is_simplejump)
1659 {
1660 emit_barrier_after (emit_insn_before (gen_trap (), insn));
1661 delete_jump (insn);
1662 changed = 1;
1663 continue;
1664 }
1665 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
1666 XEXP (temp2, 1),
1667 TRAP_CODE (PATTERN (temp)));
1668 if (new)
1669 {
1670 emit_insn_before (new, temp4);
1671 delete_jump (insn);
1672 changed = 1;
1673 continue;
1674 }
1675 }
1676 /* If the trap condition and jump condition are mutually
1677 exclusive, redirect the jump to the following insn. */
1678 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
1679 && ! this_is_simplejump
1680 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
1681 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
1682 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
1683 && redirect_jump (insn, get_label_after (temp)))
1684 {
1685 changed = 1;
1686 continue;
1687 }
1688 }
1689 #endif
1690
1691 /* Detect a conditional jump jumping over an unconditional jump. */
1692
1693 else if ((this_is_condjump || this_is_condjump_in_parallel)
1694 && ! this_is_simplejump
1695 && reallabelprev != 0
1696 && GET_CODE (reallabelprev) == JUMP_INSN
1697 && prev_active_insn (reallabelprev) == insn
1698 && no_labels_between_p (insn, reallabelprev)
1699 && simplejump_p (reallabelprev))
1700 {
1701 /* When we invert the unconditional jump, we will be
1702 decrementing the usage count of its old label.
1703 Make sure that we don't delete it now because that
1704 might cause the following code to be deleted. */
1705 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1706 rtx prev_label = JUMP_LABEL (insn);
1707
1708 if (prev_label)
1709 ++LABEL_NUSES (prev_label);
1710
1711 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1712 {
1713 /* It is very likely that if there are USE insns before
1714 this jump, they hold REG_DEAD notes. These REG_DEAD
1715 notes are no longer valid due to this optimization,
1716 and will cause the life-analysis that following passes
1717 (notably delayed-branch scheduling) to think that
1718 these registers are dead when they are not.
1719
1720 To prevent this trouble, we just remove the USE insns
1721 from the insn chain. */
1722
1723 while (prev_uses && GET_CODE (prev_uses) == INSN
1724 && GET_CODE (PATTERN (prev_uses)) == USE)
1725 {
1726 rtx useless = prev_uses;
1727 prev_uses = prev_nonnote_insn (prev_uses);
1728 delete_insn (useless);
1729 }
1730
1731 delete_insn (reallabelprev);
1732 next = insn;
1733 changed = 1;
1734 }
1735
1736 /* We can now safely delete the label if it is unreferenced
1737 since the delete_insn above has deleted the BARRIER. */
1738 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1739 delete_insn (prev_label);
1740 continue;
1741 }
1742 else
1743 {
1744 /* Detect a jump to a jump. */
1745
1746 nlabel = follow_jumps (JUMP_LABEL (insn));
1747 if (nlabel != JUMP_LABEL (insn)
1748 && redirect_jump (insn, nlabel))
1749 {
1750 changed = 1;
1751 next = insn;
1752 }
1753
1754 /* Look for if (foo) bar; else break; */
1755 /* The insns look like this:
1756 insn = condjump label1;
1757 ...range1 (some insns)...
1758 jump label2;
1759 label1:
1760 ...range2 (some insns)...
1761 jump somewhere unconditionally
1762 label2: */
1763 {
1764 rtx label1 = next_label (insn);
1765 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1766 /* Don't do this optimization on the first round, so that
1767 jump-around-a-jump gets simplified before we ask here
1768 whether a jump is unconditional.
1769
1770 Also don't do it when we are called after reload since
1771 it will confuse reorg. */
1772 if (! first
1773 && (reload_completed ? ! flag_delayed_branch : 1)
1774 /* Make sure INSN is something we can invert. */
1775 && condjump_p (insn)
1776 && label1 != 0
1777 && JUMP_LABEL (insn) == label1
1778 && LABEL_NUSES (label1) == 1
1779 && GET_CODE (range1end) == JUMP_INSN
1780 && simplejump_p (range1end))
1781 {
1782 rtx label2 = next_label (label1);
1783 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1784 if (range1end != range2end
1785 && JUMP_LABEL (range1end) == label2
1786 && GET_CODE (range2end) == JUMP_INSN
1787 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1788 /* Invert the jump condition, so we
1789 still execute the same insns in each case. */
1790 && invert_jump (insn, label1))
1791 {
1792 rtx range1beg = next_active_insn (insn);
1793 rtx range2beg = next_active_insn (label1);
1794 rtx range1after, range2after;
1795 rtx range1before, range2before;
1796 rtx rangenext;
1797
1798 /* Include in each range any notes before it, to be
1799 sure that we get the line number note if any, even
1800 if there are other notes here. */
1801 while (PREV_INSN (range1beg)
1802 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1803 range1beg = PREV_INSN (range1beg);
1804
1805 while (PREV_INSN (range2beg)
1806 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1807 range2beg = PREV_INSN (range2beg);
1808
1809 /* Don't move NOTEs for blocks or loops; shift them
1810 outside the ranges, where they'll stay put. */
1811 range1beg = squeeze_notes (range1beg, range1end);
1812 range2beg = squeeze_notes (range2beg, range2end);
1813
1814 /* Get current surrounds of the 2 ranges. */
1815 range1before = PREV_INSN (range1beg);
1816 range2before = PREV_INSN (range2beg);
1817 range1after = NEXT_INSN (range1end);
1818 range2after = NEXT_INSN (range2end);
1819
1820 /* Splice range2 where range1 was. */
1821 NEXT_INSN (range1before) = range2beg;
1822 PREV_INSN (range2beg) = range1before;
1823 NEXT_INSN (range2end) = range1after;
1824 PREV_INSN (range1after) = range2end;
1825 /* Splice range1 where range2 was. */
1826 NEXT_INSN (range2before) = range1beg;
1827 PREV_INSN (range1beg) = range2before;
1828 NEXT_INSN (range1end) = range2after;
1829 PREV_INSN (range2after) = range1end;
1830
1831 /* Check for a loop end note between the end of
1832 range2, and the next code label. If there is one,
1833 then what we have really seen is
1834 if (foo) break; end_of_loop;
1835 and moved the break sequence outside the loop.
1836 We must move the LOOP_END note to where the
1837 loop really ends now, or we will confuse loop
1838 optimization. Stop if we find a LOOP_BEG note
1839 first, since we don't want to move the LOOP_END
1840 note in that case. */
1841 for (;range2after != label2; range2after = rangenext)
1842 {
1843 rangenext = NEXT_INSN (range2after);
1844 if (GET_CODE (range2after) == NOTE)
1845 {
1846 if (NOTE_LINE_NUMBER (range2after)
1847 == NOTE_INSN_LOOP_END)
1848 {
1849 NEXT_INSN (PREV_INSN (range2after))
1850 = rangenext;
1851 PREV_INSN (rangenext)
1852 = PREV_INSN (range2after);
1853 PREV_INSN (range2after)
1854 = PREV_INSN (range1beg);
1855 NEXT_INSN (range2after) = range1beg;
1856 NEXT_INSN (PREV_INSN (range1beg))
1857 = range2after;
1858 PREV_INSN (range1beg) = range2after;
1859 }
1860 else if (NOTE_LINE_NUMBER (range2after)
1861 == NOTE_INSN_LOOP_BEG)
1862 break;
1863 }
1864 }
1865 changed = 1;
1866 continue;
1867 }
1868 }
1869 }
1870
1871 /* Now that the jump has been tensioned,
1872 try cross jumping: check for identical code
1873 before the jump and before its target label. */
1874
1875 /* First, cross jumping of conditional jumps: */
1876
1877 if (cross_jump && condjump_p (insn))
1878 {
1879 rtx newjpos, newlpos;
1880 rtx x = prev_real_insn (JUMP_LABEL (insn));
1881
1882 /* A conditional jump may be crossjumped
1883 only if the place it jumps to follows
1884 an opposing jump that comes back here. */
1885
1886 if (x != 0 && ! jump_back_p (x, insn))
1887 /* We have no opposing jump;
1888 cannot cross jump this insn. */
1889 x = 0;
1890
1891 newjpos = 0;
1892 /* TARGET is nonzero if it is ok to cross jump
1893 to code before TARGET. If so, see if matches. */
1894 if (x != 0)
1895 find_cross_jump (insn, x, 2,
1896 &newjpos, &newlpos);
1897
1898 if (newjpos != 0)
1899 {
1900 do_cross_jump (insn, newjpos, newlpos);
1901 /* Make the old conditional jump
1902 into an unconditional one. */
1903 SET_SRC (PATTERN (insn))
1904 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
1905 INSN_CODE (insn) = -1;
1906 emit_barrier_after (insn);
1907 /* Add to jump_chain unless this is a new label
1908 whose UID is too large. */
1909 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1910 {
1911 jump_chain[INSN_UID (insn)]
1912 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1913 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1914 }
1915 changed = 1;
1916 next = insn;
1917 }
1918 }
1919
1920 /* Cross jumping of unconditional jumps:
1921 a few differences. */
1922
1923 if (cross_jump && simplejump_p (insn))
1924 {
1925 rtx newjpos, newlpos;
1926 rtx target;
1927
1928 newjpos = 0;
1929
1930 /* TARGET is nonzero if it is ok to cross jump
1931 to code before TARGET. If so, see if matches. */
1932 find_cross_jump (insn, JUMP_LABEL (insn), 1,
1933 &newjpos, &newlpos);
1934
1935 /* If cannot cross jump to code before the label,
1936 see if we can cross jump to another jump to
1937 the same label. */
1938 /* Try each other jump to this label. */
1939 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
1940 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1941 target != 0 && newjpos == 0;
1942 target = jump_chain[INSN_UID (target)])
1943 if (target != insn
1944 && JUMP_LABEL (target) == JUMP_LABEL (insn)
1945 /* Ignore TARGET if it's deleted. */
1946 && ! INSN_DELETED_P (target))
1947 find_cross_jump (insn, target, 2,
1948 &newjpos, &newlpos);
1949
1950 if (newjpos != 0)
1951 {
1952 do_cross_jump (insn, newjpos, newlpos);
1953 changed = 1;
1954 next = insn;
1955 }
1956 }
1957
1958 /* This code was dead in the previous jump.c! */
1959 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
1960 {
1961 /* Return insns all "jump to the same place"
1962 so we can cross-jump between any two of them. */
1963
1964 rtx newjpos, newlpos, target;
1965
1966 newjpos = 0;
1967
1968 /* If cannot cross jump to code before the label,
1969 see if we can cross jump to another jump to
1970 the same label. */
1971 /* Try each other jump to this label. */
1972 for (target = jump_chain[0];
1973 target != 0 && newjpos == 0;
1974 target = jump_chain[INSN_UID (target)])
1975 if (target != insn
1976 && ! INSN_DELETED_P (target)
1977 && GET_CODE (PATTERN (target)) == RETURN)
1978 find_cross_jump (insn, target, 2,
1979 &newjpos, &newlpos);
1980
1981 if (newjpos != 0)
1982 {
1983 do_cross_jump (insn, newjpos, newlpos);
1984 changed = 1;
1985 next = insn;
1986 }
1987 }
1988 }
1989 }
1990
1991 first = 0;
1992 }
1993
1994 /* Delete extraneous line number notes.
1995 Note that two consecutive notes for different lines are not really
1996 extraneous. There should be some indication where that line belonged,
1997 even if it became empty. */
1998
1999 {
2000 rtx last_note = 0;
2001
2002 for (insn = f; insn; insn = NEXT_INSN (insn))
2003 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2004 {
2005 /* Delete this note if it is identical to previous note. */
2006 if (last_note
2007 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2008 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2009 {
2010 delete_insn (insn);
2011 continue;
2012 }
2013
2014 last_note = insn;
2015 }
2016 }
2017
2018 #ifdef HAVE_return
2019 if (HAVE_return)
2020 {
2021 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2022 in front of it. If the machine allows it at this point (we might be
2023 after reload for a leaf routine), it will improve optimization for it
2024 to be there. We do this both here and at the start of this pass since
2025 the RETURN might have been deleted by some of our optimizations. */
2026 insn = get_last_insn ();
2027 while (insn && GET_CODE (insn) == NOTE)
2028 insn = PREV_INSN (insn);
2029
2030 if (insn && GET_CODE (insn) != BARRIER)
2031 {
2032 emit_jump_insn (gen_return ());
2033 emit_barrier ();
2034 }
2035 }
2036 #endif
2037
2038 can_reach_end = calculate_can_reach_end (last_insn, 0, 1);
2039
2040 /* Show JUMP_CHAIN no longer valid. */
2041 jump_chain = 0;
2042 }
2043 \f
2044 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2045 notes whose labels don't occur in the insn any more. Returns the
2046 largest INSN_UID found. */
2047 static int
2048 init_label_info (f)
2049 rtx f;
2050 {
2051 int largest_uid = 0;
2052 rtx insn;
2053
2054 for (insn = f; insn; insn = NEXT_INSN (insn))
2055 {
2056 if (GET_CODE (insn) == CODE_LABEL)
2057 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
2058 else if (GET_CODE (insn) == JUMP_INSN)
2059 JUMP_LABEL (insn) = 0;
2060 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2061 {
2062 rtx note, next;
2063
2064 for (note = REG_NOTES (insn); note; note = next)
2065 {
2066 next = XEXP (note, 1);
2067 if (REG_NOTE_KIND (note) == REG_LABEL
2068 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
2069 remove_note (insn, note);
2070 }
2071 }
2072 if (INSN_UID (insn) > largest_uid)
2073 largest_uid = INSN_UID (insn);
2074 }
2075
2076 return largest_uid;
2077 }
2078
2079 /* Delete insns following barriers, up to next label. */
2080 static void
2081 delete_barrier_successors (f)
2082 rtx f;
2083 {
2084 rtx insn;
2085
2086 for (insn = f; insn;)
2087 {
2088 if (GET_CODE (insn) == BARRIER)
2089 {
2090 insn = NEXT_INSN (insn);
2091 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
2092 {
2093 if (GET_CODE (insn) == NOTE
2094 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2095 insn = NEXT_INSN (insn);
2096 else
2097 insn = delete_insn (insn);
2098 }
2099 /* INSN is now the code_label. */
2100 }
2101 else
2102 insn = NEXT_INSN (insn);
2103 }
2104 }
2105
2106 /* Mark the label each jump jumps to.
2107 Combine consecutive labels, and count uses of labels.
2108
2109 For each label, make a chain (using `jump_chain')
2110 of all the *unconditional* jumps that jump to it;
2111 also make a chain of all returns.
2112
2113 CROSS_JUMP indicates whether we are doing cross jumping
2114 and if we are whether we will be paying attention to
2115 death notes or not. */
2116
2117 static void
2118 mark_all_labels (f, cross_jump)
2119 rtx f;
2120 int cross_jump;
2121 {
2122 rtx insn;
2123
2124 for (insn = f; insn; insn = NEXT_INSN (insn))
2125 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2126 {
2127 mark_jump_label (PATTERN (insn), insn, cross_jump);
2128 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
2129 {
2130 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2131 {
2132 jump_chain[INSN_UID (insn)]
2133 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2134 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2135 }
2136 if (GET_CODE (PATTERN (insn)) == RETURN)
2137 {
2138 jump_chain[INSN_UID (insn)] = jump_chain[0];
2139 jump_chain[0] = insn;
2140 }
2141 }
2142 }
2143 }
2144
2145 /* Delete all labels already not referenced.
2146 Also find and return the last insn. */
2147
2148 static rtx
2149 delete_unreferenced_labels (f)
2150 rtx f;
2151 {
2152 rtx final = NULL_RTX;
2153 rtx insn;
2154
2155 for (insn = f; insn; )
2156 {
2157 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
2158 insn = delete_insn (insn);
2159 else
2160 {
2161 final = insn;
2162 insn = NEXT_INSN (insn);
2163 }
2164 }
2165
2166 return final;
2167 }
2168
2169 /* Delete various simple forms of moves which have no necessary
2170 side effect. */
2171
2172 static void
2173 delete_noop_moves (f)
2174 rtx f;
2175 {
2176 rtx insn, next;
2177
2178 for (insn = f; insn; )
2179 {
2180 next = NEXT_INSN (insn);
2181
2182 if (GET_CODE (insn) == INSN)
2183 {
2184 register rtx body = PATTERN (insn);
2185
2186 /* Combine stack_adjusts with following push_insns. */
2187 #ifdef PUSH_ROUNDING
2188 if (GET_CODE (body) == SET
2189 && SET_DEST (body) == stack_pointer_rtx
2190 && GET_CODE (SET_SRC (body)) == PLUS
2191 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
2192 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
2193 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
2194 {
2195 rtx p;
2196 rtx stack_adjust_insn = insn;
2197 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
2198 int total_pushed = 0;
2199 int pushes = 0;
2200
2201 /* Find all successive push insns. */
2202 p = insn;
2203 /* Don't convert more than three pushes;
2204 that starts adding too many displaced addresses
2205 and the whole thing starts becoming a losing
2206 proposition. */
2207 while (pushes < 3)
2208 {
2209 rtx pbody, dest;
2210 p = next_nonnote_insn (p);
2211 if (p == 0 || GET_CODE (p) != INSN)
2212 break;
2213 pbody = PATTERN (p);
2214 if (GET_CODE (pbody) != SET)
2215 break;
2216 dest = SET_DEST (pbody);
2217 /* Allow a no-op move between the adjust and the push. */
2218 if (GET_CODE (dest) == REG
2219 && GET_CODE (SET_SRC (pbody)) == REG
2220 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2221 continue;
2222 if (! (GET_CODE (dest) == MEM
2223 && GET_CODE (XEXP (dest, 0)) == POST_INC
2224 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2225 break;
2226 pushes++;
2227 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
2228 > stack_adjust_amount)
2229 break;
2230 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2231 }
2232
2233 /* Discard the amount pushed from the stack adjust;
2234 maybe eliminate it entirely. */
2235 if (total_pushed >= stack_adjust_amount)
2236 {
2237 delete_computation (stack_adjust_insn);
2238 total_pushed = stack_adjust_amount;
2239 }
2240 else
2241 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
2242 = GEN_INT (stack_adjust_amount - total_pushed);
2243
2244 /* Change the appropriate push insns to ordinary stores. */
2245 p = insn;
2246 while (total_pushed > 0)
2247 {
2248 rtx pbody, dest;
2249 p = next_nonnote_insn (p);
2250 if (GET_CODE (p) != INSN)
2251 break;
2252 pbody = PATTERN (p);
2253 if (GET_CODE (pbody) != SET)
2254 break;
2255 dest = SET_DEST (pbody);
2256 /* Allow a no-op move between the adjust and the push. */
2257 if (GET_CODE (dest) == REG
2258 && GET_CODE (SET_SRC (pbody)) == REG
2259 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2260 continue;
2261 if (! (GET_CODE (dest) == MEM
2262 && GET_CODE (XEXP (dest, 0)) == POST_INC
2263 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2264 break;
2265 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2266 /* If this push doesn't fully fit in the space
2267 of the stack adjust that we deleted,
2268 make another stack adjust here for what we
2269 didn't use up. There should be peepholes
2270 to recognize the resulting sequence of insns. */
2271 if (total_pushed < 0)
2272 {
2273 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
2274 GEN_INT (- total_pushed)),
2275 p);
2276 break;
2277 }
2278 XEXP (dest, 0)
2279 = plus_constant (stack_pointer_rtx, total_pushed);
2280 }
2281 }
2282 #endif
2283
2284 /* Detect and delete no-op move instructions
2285 resulting from not allocating a parameter in a register. */
2286
2287 if (GET_CODE (body) == SET
2288 && (SET_DEST (body) == SET_SRC (body)
2289 || (GET_CODE (SET_DEST (body)) == MEM
2290 && GET_CODE (SET_SRC (body)) == MEM
2291 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
2292 && ! (GET_CODE (SET_DEST (body)) == MEM
2293 && MEM_VOLATILE_P (SET_DEST (body)))
2294 && ! (GET_CODE (SET_SRC (body)) == MEM
2295 && MEM_VOLATILE_P (SET_SRC (body))))
2296 delete_computation (insn);
2297
2298 /* Detect and ignore no-op move instructions
2299 resulting from smart or fortuitous register allocation. */
2300
2301 else if (GET_CODE (body) == SET)
2302 {
2303 int sreg = true_regnum (SET_SRC (body));
2304 int dreg = true_regnum (SET_DEST (body));
2305
2306 if (sreg == dreg && sreg >= 0)
2307 delete_insn (insn);
2308 else if (sreg >= 0 && dreg >= 0)
2309 {
2310 rtx trial;
2311 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
2312 sreg, NULL_PTR, dreg,
2313 GET_MODE (SET_SRC (body)));
2314
2315 if (tem != 0
2316 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
2317 {
2318 /* DREG may have been the target of a REG_DEAD note in
2319 the insn which makes INSN redundant. If so, reorg
2320 would still think it is dead. So search for such a
2321 note and delete it if we find it. */
2322 if (! find_regno_note (insn, REG_UNUSED, dreg))
2323 for (trial = prev_nonnote_insn (insn);
2324 trial && GET_CODE (trial) != CODE_LABEL;
2325 trial = prev_nonnote_insn (trial))
2326 if (find_regno_note (trial, REG_DEAD, dreg))
2327 {
2328 remove_death (dreg, trial);
2329 break;
2330 }
2331
2332 /* Deleting insn could lose a death-note for SREG. */
2333 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
2334 {
2335 /* Change this into a USE so that we won't emit
2336 code for it, but still can keep the note. */
2337 PATTERN (insn)
2338 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
2339 INSN_CODE (insn) = -1;
2340 /* Remove all reg notes but the REG_DEAD one. */
2341 REG_NOTES (insn) = trial;
2342 XEXP (trial, 1) = NULL_RTX;
2343 }
2344 else
2345 delete_insn (insn);
2346 }
2347 }
2348 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
2349 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
2350 NULL_PTR, 0,
2351 GET_MODE (SET_DEST (body))))
2352 {
2353 /* This handles the case where we have two consecutive
2354 assignments of the same constant to pseudos that didn't
2355 get a hard reg. Each SET from the constant will be
2356 converted into a SET of the spill register and an
2357 output reload will be made following it. This produces
2358 two loads of the same constant into the same spill
2359 register. */
2360
2361 rtx in_insn = insn;
2362
2363 /* Look back for a death note for the first reg.
2364 If there is one, it is no longer accurate. */
2365 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
2366 {
2367 if ((GET_CODE (in_insn) == INSN
2368 || GET_CODE (in_insn) == JUMP_INSN)
2369 && find_regno_note (in_insn, REG_DEAD, dreg))
2370 {
2371 remove_death (dreg, in_insn);
2372 break;
2373 }
2374 in_insn = PREV_INSN (in_insn);
2375 }
2376
2377 /* Delete the second load of the value. */
2378 delete_insn (insn);
2379 }
2380 }
2381 else if (GET_CODE (body) == PARALLEL)
2382 {
2383 /* If each part is a set between two identical registers or
2384 a USE or CLOBBER, delete the insn. */
2385 int i, sreg, dreg;
2386 rtx tem;
2387
2388 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
2389 {
2390 tem = XVECEXP (body, 0, i);
2391 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
2392 continue;
2393
2394 if (GET_CODE (tem) != SET
2395 || (sreg = true_regnum (SET_SRC (tem))) < 0
2396 || (dreg = true_regnum (SET_DEST (tem))) < 0
2397 || dreg != sreg)
2398 break;
2399 }
2400
2401 if (i < 0)
2402 delete_insn (insn);
2403 }
2404 /* Also delete insns to store bit fields if they are no-ops. */
2405 /* Not worth the hair to detect this in the big-endian case. */
2406 else if (! BYTES_BIG_ENDIAN
2407 && GET_CODE (body) == SET
2408 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
2409 && XEXP (SET_DEST (body), 2) == const0_rtx
2410 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
2411 && ! (GET_CODE (SET_SRC (body)) == MEM
2412 && MEM_VOLATILE_P (SET_SRC (body))))
2413 delete_insn (insn);
2414 }
2415 insn = next;
2416 }
2417 }
2418
2419 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2420 If so indicate that this function can drop off the end by returning
2421 1, else return 0.
2422
2423 CHECK_DELETED indicates whether we must check if the note being
2424 searched for has the deleted flag set.
2425
2426 DELETE_FINAL_NOTE indicates whether we should delete the note
2427 if we find it. */
2428
2429 static int
2430 calculate_can_reach_end (last, check_deleted, delete_final_note)
2431 rtx last;
2432 int check_deleted;
2433 int delete_final_note;
2434 {
2435 rtx insn = last;
2436 int n_labels = 1;
2437
2438 while (insn != NULL_RTX)
2439 {
2440 int ok = 0;
2441
2442 /* One label can follow the end-note: the return label. */
2443 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2444 ok = 1;
2445 /* Ordinary insns can follow it if returning a structure. */
2446 else if (GET_CODE (insn) == INSN)
2447 ok = 1;
2448 /* If machine uses explicit RETURN insns, no epilogue,
2449 then one of them follows the note. */
2450 else if (GET_CODE (insn) == JUMP_INSN
2451 && GET_CODE (PATTERN (insn)) == RETURN)
2452 ok = 1;
2453 /* A barrier can follow the return insn. */
2454 else if (GET_CODE (insn) == BARRIER)
2455 ok = 1;
2456 /* Other kinds of notes can follow also. */
2457 else if (GET_CODE (insn) == NOTE
2458 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2459 ok = 1;
2460
2461 if (ok != 1)
2462 break;
2463
2464 insn = PREV_INSN (insn);
2465 }
2466
2467 /* See if we backed up to the appropriate type of note. */
2468 if (insn != NULL_RTX
2469 && GET_CODE (insn) == NOTE
2470 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
2471 && (check_deleted == 0
2472 || ! INSN_DELETED_P (insn)))
2473 {
2474 if (delete_final_note)
2475 delete_insn (insn);
2476 return 1;
2477 }
2478
2479 return 0;
2480 }
2481
2482 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2483 jump. Assume that this unconditional jump is to the exit test code. If
2484 the code is sufficiently simple, make a copy of it before INSN,
2485 followed by a jump to the exit of the loop. Then delete the unconditional
2486 jump after INSN.
2487
2488 Return 1 if we made the change, else 0.
2489
2490 This is only safe immediately after a regscan pass because it uses the
2491 values of regno_first_uid and regno_last_uid. */
2492
2493 static int
2494 duplicate_loop_exit_test (loop_start)
2495 rtx loop_start;
2496 {
2497 rtx insn, set, reg, p, link;
2498 rtx copy = 0;
2499 int num_insns = 0;
2500 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2501 rtx lastexit;
2502 int max_reg = max_reg_num ();
2503 rtx *reg_map = 0;
2504
2505 /* Scan the exit code. We do not perform this optimization if any insn:
2506
2507 is a CALL_INSN
2508 is a CODE_LABEL
2509 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2510 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2511 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2512 is not valid.
2513
2514 We also do not do this if we find an insn with ASM_OPERANDS. While
2515 this restriction should not be necessary, copying an insn with
2516 ASM_OPERANDS can confuse asm_noperands in some cases.
2517
2518 Also, don't do this if the exit code is more than 20 insns. */
2519
2520 for (insn = exitcode;
2521 insn
2522 && ! (GET_CODE (insn) == NOTE
2523 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2524 insn = NEXT_INSN (insn))
2525 {
2526 switch (GET_CODE (insn))
2527 {
2528 case CODE_LABEL:
2529 case CALL_INSN:
2530 return 0;
2531 case NOTE:
2532 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2533 a jump immediately after the loop start that branches outside
2534 the loop but within an outer loop, near the exit test.
2535 If we copied this exit test and created a phony
2536 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2537 before the exit test look like these could be safely moved
2538 out of the loop even if they actually may be never executed.
2539 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2540
2541 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2542 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2543 return 0;
2544
2545 if (optimize < 2
2546 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2547 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
2548 /* If we were to duplicate this code, we would not move
2549 the BLOCK notes, and so debugging the moved code would
2550 be difficult. Thus, we only move the code with -O2 or
2551 higher. */
2552 return 0;
2553
2554 break;
2555 case JUMP_INSN:
2556 case INSN:
2557 /* The code below would grossly mishandle REG_WAS_0 notes,
2558 so get rid of them here. */
2559 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
2560 remove_note (insn, p);
2561 if (++num_insns > 20
2562 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2563 || find_reg_note (insn, REG_LIBCALL, NULL_RTX)
2564 || asm_noperands (PATTERN (insn)) > 0)
2565 return 0;
2566 break;
2567 default:
2568 break;
2569 }
2570 }
2571
2572 /* Unless INSN is zero, we can do the optimization. */
2573 if (insn == 0)
2574 return 0;
2575
2576 lastexit = insn;
2577
2578 /* See if any insn sets a register only used in the loop exit code and
2579 not a user variable. If so, replace it with a new register. */
2580 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2581 if (GET_CODE (insn) == INSN
2582 && (set = single_set (insn)) != 0
2583 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2584 || (GET_CODE (reg) == SUBREG
2585 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2586 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2587 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2588 {
2589 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2590 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2591 break;
2592
2593 if (p != lastexit)
2594 {
2595 /* We can do the replacement. Allocate reg_map if this is the
2596 first replacement we found. */
2597 if (reg_map == 0)
2598 {
2599 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2600 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2601 }
2602
2603 REG_LOOP_TEST_P (reg) = 1;
2604
2605 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2606 }
2607 }
2608
2609 /* Now copy each insn. */
2610 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2611 switch (GET_CODE (insn))
2612 {
2613 case BARRIER:
2614 copy = emit_barrier_before (loop_start);
2615 break;
2616 case NOTE:
2617 /* Only copy line-number notes. */
2618 if (NOTE_LINE_NUMBER (insn) >= 0)
2619 {
2620 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2621 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2622 }
2623 break;
2624
2625 case INSN:
2626 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2627 if (reg_map)
2628 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2629
2630 mark_jump_label (PATTERN (copy), copy, 0);
2631
2632 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2633 make them. */
2634 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2635 if (REG_NOTE_KIND (link) != REG_LABEL)
2636 REG_NOTES (copy)
2637 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2638 XEXP (link, 0),
2639 REG_NOTES (copy)));
2640 if (reg_map && REG_NOTES (copy))
2641 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2642 break;
2643
2644 case JUMP_INSN:
2645 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2646 if (reg_map)
2647 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2648 mark_jump_label (PATTERN (copy), copy, 0);
2649 if (REG_NOTES (insn))
2650 {
2651 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2652 if (reg_map)
2653 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2654 }
2655
2656 /* If this is a simple jump, add it to the jump chain. */
2657
2658 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2659 && simplejump_p (copy))
2660 {
2661 jump_chain[INSN_UID (copy)]
2662 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2663 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2664 }
2665 break;
2666
2667 default:
2668 abort ();
2669 }
2670
2671 /* Now clean up by emitting a jump to the end label and deleting the jump
2672 at the start of the loop. */
2673 if (! copy || GET_CODE (copy) != BARRIER)
2674 {
2675 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2676 loop_start);
2677 mark_jump_label (PATTERN (copy), copy, 0);
2678 if (INSN_UID (copy) < max_jump_chain
2679 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2680 {
2681 jump_chain[INSN_UID (copy)]
2682 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2683 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2684 }
2685 emit_barrier_before (loop_start);
2686 }
2687
2688 /* Mark the exit code as the virtual top of the converted loop. */
2689 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2690
2691 delete_insn (next_nonnote_insn (loop_start));
2692
2693 return 1;
2694 }
2695 \f
2696 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2697 loop-end notes between START and END out before START. Assume that
2698 END is not such a note. START may be such a note. Returns the value
2699 of the new starting insn, which may be different if the original start
2700 was such a note. */
2701
2702 rtx
2703 squeeze_notes (start, end)
2704 rtx start, end;
2705 {
2706 rtx insn;
2707 rtx next;
2708
2709 for (insn = start; insn != end; insn = next)
2710 {
2711 next = NEXT_INSN (insn);
2712 if (GET_CODE (insn) == NOTE
2713 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2714 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2715 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2716 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2717 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2718 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2719 {
2720 if (insn == start)
2721 start = next;
2722 else
2723 {
2724 rtx prev = PREV_INSN (insn);
2725 PREV_INSN (insn) = PREV_INSN (start);
2726 NEXT_INSN (insn) = start;
2727 NEXT_INSN (PREV_INSN (insn)) = insn;
2728 PREV_INSN (NEXT_INSN (insn)) = insn;
2729 NEXT_INSN (prev) = next;
2730 PREV_INSN (next) = prev;
2731 }
2732 }
2733 }
2734
2735 return start;
2736 }
2737 \f
2738 /* Compare the instructions before insn E1 with those before E2
2739 to find an opportunity for cross jumping.
2740 (This means detecting identical sequences of insns followed by
2741 jumps to the same place, or followed by a label and a jump
2742 to that label, and replacing one with a jump to the other.)
2743
2744 Assume E1 is a jump that jumps to label E2
2745 (that is not always true but it might as well be).
2746 Find the longest possible equivalent sequences
2747 and store the first insns of those sequences into *F1 and *F2.
2748 Store zero there if no equivalent preceding instructions are found.
2749
2750 We give up if we find a label in stream 1.
2751 Actually we could transfer that label into stream 2. */
2752
2753 static void
2754 find_cross_jump (e1, e2, minimum, f1, f2)
2755 rtx e1, e2;
2756 int minimum;
2757 rtx *f1, *f2;
2758 {
2759 register rtx i1 = e1, i2 = e2;
2760 register rtx p1, p2;
2761 int lose = 0;
2762
2763 rtx last1 = 0, last2 = 0;
2764 rtx afterlast1 = 0, afterlast2 = 0;
2765
2766 *f1 = 0;
2767 *f2 = 0;
2768
2769 while (1)
2770 {
2771 i1 = prev_nonnote_insn (i1);
2772
2773 i2 = PREV_INSN (i2);
2774 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2775 i2 = PREV_INSN (i2);
2776
2777 if (i1 == 0)
2778 break;
2779
2780 /* Don't allow the range of insns preceding E1 or E2
2781 to include the other (E2 or E1). */
2782 if (i2 == e1 || i1 == e2)
2783 break;
2784
2785 /* If we will get to this code by jumping, those jumps will be
2786 tensioned to go directly to the new label (before I2),
2787 so this cross-jumping won't cost extra. So reduce the minimum. */
2788 if (GET_CODE (i1) == CODE_LABEL)
2789 {
2790 --minimum;
2791 break;
2792 }
2793
2794 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2795 break;
2796
2797 /* Avoid moving insns across EH regions if either of the insns
2798 can throw. */
2799 if (flag_exceptions
2800 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
2801 && !in_same_eh_region (i1, i2))
2802 break;
2803
2804 p1 = PATTERN (i1);
2805 p2 = PATTERN (i2);
2806
2807 /* If this is a CALL_INSN, compare register usage information.
2808 If we don't check this on stack register machines, the two
2809 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2810 numbers of stack registers in the same basic block.
2811 If we don't check this on machines with delay slots, a delay slot may
2812 be filled that clobbers a parameter expected by the subroutine.
2813
2814 ??? We take the simple route for now and assume that if they're
2815 equal, they were constructed identically. */
2816
2817 if (GET_CODE (i1) == CALL_INSN
2818 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2819 CALL_INSN_FUNCTION_USAGE (i2)))
2820 lose = 1;
2821
2822 #ifdef STACK_REGS
2823 /* If cross_jump_death_matters is not 0, the insn's mode
2824 indicates whether or not the insn contains any stack-like
2825 regs. */
2826
2827 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2828 {
2829 /* If register stack conversion has already been done, then
2830 death notes must also be compared before it is certain that
2831 the two instruction streams match. */
2832
2833 rtx note;
2834 HARD_REG_SET i1_regset, i2_regset;
2835
2836 CLEAR_HARD_REG_SET (i1_regset);
2837 CLEAR_HARD_REG_SET (i2_regset);
2838
2839 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2840 if (REG_NOTE_KIND (note) == REG_DEAD
2841 && STACK_REG_P (XEXP (note, 0)))
2842 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2843
2844 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2845 if (REG_NOTE_KIND (note) == REG_DEAD
2846 && STACK_REG_P (XEXP (note, 0)))
2847 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2848
2849 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2850
2851 lose = 1;
2852
2853 done:
2854 ;
2855 }
2856 #endif
2857
2858 /* Don't allow old-style asm or volatile extended asms to be accepted
2859 for cross jumping purposes. It is conceptually correct to allow
2860 them, since cross-jumping preserves the dynamic instruction order
2861 even though it is changing the static instruction order. However,
2862 if an asm is being used to emit an assembler pseudo-op, such as
2863 the MIPS `.set reorder' pseudo-op, then the static instruction order
2864 matters and it must be preserved. */
2865 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
2866 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
2867 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
2868 lose = 1;
2869
2870 if (lose || GET_CODE (p1) != GET_CODE (p2)
2871 || ! rtx_renumbered_equal_p (p1, p2))
2872 {
2873 /* The following code helps take care of G++ cleanups. */
2874 rtx equiv1;
2875 rtx equiv2;
2876
2877 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2878 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2879 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2880 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2881 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2882 /* If the equivalences are not to a constant, they may
2883 reference pseudos that no longer exist, so we can't
2884 use them. */
2885 && CONSTANT_P (XEXP (equiv1, 0))
2886 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2887 {
2888 rtx s1 = single_set (i1);
2889 rtx s2 = single_set (i2);
2890 if (s1 != 0 && s2 != 0
2891 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2892 {
2893 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2894 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2895 if (! rtx_renumbered_equal_p (p1, p2))
2896 cancel_changes (0);
2897 else if (apply_change_group ())
2898 goto win;
2899 }
2900 }
2901
2902 /* Insns fail to match; cross jumping is limited to the following
2903 insns. */
2904
2905 #ifdef HAVE_cc0
2906 /* Don't allow the insn after a compare to be shared by
2907 cross-jumping unless the compare is also shared.
2908 Here, if either of these non-matching insns is a compare,
2909 exclude the following insn from possible cross-jumping. */
2910 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2911 last1 = afterlast1, last2 = afterlast2, ++minimum;
2912 #endif
2913
2914 /* If cross-jumping here will feed a jump-around-jump
2915 optimization, this jump won't cost extra, so reduce
2916 the minimum. */
2917 if (GET_CODE (i1) == JUMP_INSN
2918 && JUMP_LABEL (i1)
2919 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2920 --minimum;
2921 break;
2922 }
2923
2924 win:
2925 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2926 {
2927 /* Ok, this insn is potentially includable in a cross-jump here. */
2928 afterlast1 = last1, afterlast2 = last2;
2929 last1 = i1, last2 = i2, --minimum;
2930 }
2931 }
2932
2933 if (minimum <= 0 && last1 != 0 && last1 != e1)
2934 *f1 = last1, *f2 = last2;
2935 }
2936
2937 static void
2938 do_cross_jump (insn, newjpos, newlpos)
2939 rtx insn, newjpos, newlpos;
2940 {
2941 /* Find an existing label at this point
2942 or make a new one if there is none. */
2943 register rtx label = get_label_before (newlpos);
2944
2945 /* Make the same jump insn jump to the new point. */
2946 if (GET_CODE (PATTERN (insn)) == RETURN)
2947 {
2948 /* Remove from jump chain of returns. */
2949 delete_from_jump_chain (insn);
2950 /* Change the insn. */
2951 PATTERN (insn) = gen_jump (label);
2952 INSN_CODE (insn) = -1;
2953 JUMP_LABEL (insn) = label;
2954 LABEL_NUSES (label)++;
2955 /* Add to new the jump chain. */
2956 if (INSN_UID (label) < max_jump_chain
2957 && INSN_UID (insn) < max_jump_chain)
2958 {
2959 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2960 jump_chain[INSN_UID (label)] = insn;
2961 }
2962 }
2963 else
2964 redirect_jump (insn, label);
2965
2966 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2967 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2968 the NEWJPOS stream. */
2969
2970 while (newjpos != insn)
2971 {
2972 rtx lnote;
2973
2974 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2975 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2976 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2977 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2978 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2979 remove_note (newlpos, lnote);
2980
2981 delete_insn (newjpos);
2982 newjpos = next_real_insn (newjpos);
2983 newlpos = next_real_insn (newlpos);
2984 }
2985 }
2986 \f
2987 /* Return the label before INSN, or put a new label there. */
2988
2989 rtx
2990 get_label_before (insn)
2991 rtx insn;
2992 {
2993 rtx label;
2994
2995 /* Find an existing label at this point
2996 or make a new one if there is none. */
2997 label = prev_nonnote_insn (insn);
2998
2999 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3000 {
3001 rtx prev = PREV_INSN (insn);
3002
3003 label = gen_label_rtx ();
3004 emit_label_after (label, prev);
3005 LABEL_NUSES (label) = 0;
3006 }
3007 return label;
3008 }
3009
3010 /* Return the label after INSN, or put a new label there. */
3011
3012 rtx
3013 get_label_after (insn)
3014 rtx insn;
3015 {
3016 rtx label;
3017
3018 /* Find an existing label at this point
3019 or make a new one if there is none. */
3020 label = next_nonnote_insn (insn);
3021
3022 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3023 {
3024 label = gen_label_rtx ();
3025 emit_label_after (label, insn);
3026 LABEL_NUSES (label) = 0;
3027 }
3028 return label;
3029 }
3030 \f
3031 /* Return 1 if INSN is a jump that jumps to right after TARGET
3032 only on the condition that TARGET itself would drop through.
3033 Assumes that TARGET is a conditional jump. */
3034
3035 static int
3036 jump_back_p (insn, target)
3037 rtx insn, target;
3038 {
3039 rtx cinsn, ctarget;
3040 enum rtx_code codei, codet;
3041
3042 if (simplejump_p (insn) || ! condjump_p (insn)
3043 || simplejump_p (target)
3044 || target != prev_real_insn (JUMP_LABEL (insn)))
3045 return 0;
3046
3047 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
3048 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
3049
3050 codei = GET_CODE (cinsn);
3051 codet = GET_CODE (ctarget);
3052
3053 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
3054 {
3055 if (! can_reverse_comparison_p (cinsn, insn))
3056 return 0;
3057 codei = reverse_condition (codei);
3058 }
3059
3060 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
3061 {
3062 if (! can_reverse_comparison_p (ctarget, target))
3063 return 0;
3064 codet = reverse_condition (codet);
3065 }
3066
3067 return (codei == codet
3068 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
3069 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
3070 }
3071 \f
3072 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3073 return non-zero if it is safe to reverse this comparison. It is if our
3074 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3075 this is known to be an integer comparison. */
3076
3077 int
3078 can_reverse_comparison_p (comparison, insn)
3079 rtx comparison;
3080 rtx insn;
3081 {
3082 rtx arg0;
3083
3084 /* If this is not actually a comparison, we can't reverse it. */
3085 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
3086 return 0;
3087
3088 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3089 /* If this is an NE comparison, it is safe to reverse it to an EQ
3090 comparison and vice versa, even for floating point. If no operands
3091 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3092 always false and NE is always true, so the reversal is also valid. */
3093 || flag_fast_math
3094 || GET_CODE (comparison) == NE
3095 || GET_CODE (comparison) == EQ)
3096 return 1;
3097
3098 arg0 = XEXP (comparison, 0);
3099
3100 /* Make sure ARG0 is one of the actual objects being compared. If we
3101 can't do this, we can't be sure the comparison can be reversed.
3102
3103 Handle cc0 and a MODE_CC register. */
3104 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
3105 #ifdef HAVE_cc0
3106 || arg0 == cc0_rtx
3107 #endif
3108 )
3109 {
3110 rtx prev = prev_nonnote_insn (insn);
3111 rtx set = single_set (prev);
3112
3113 if (set == 0 || SET_DEST (set) != arg0)
3114 return 0;
3115
3116 arg0 = SET_SRC (set);
3117
3118 if (GET_CODE (arg0) == COMPARE)
3119 arg0 = XEXP (arg0, 0);
3120 }
3121
3122 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3123 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3124 return (GET_CODE (arg0) == CONST_INT
3125 || (GET_MODE (arg0) != VOIDmode
3126 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
3127 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
3128 }
3129
3130 /* Given an rtx-code for a comparison, return the code
3131 for the negated comparison.
3132 WATCH OUT! reverse_condition is not safe to use on a jump
3133 that might be acting on the results of an IEEE floating point comparison,
3134 because of the special treatment of non-signaling nans in comparisons.
3135 Use can_reverse_comparison_p to be sure. */
3136
3137 enum rtx_code
3138 reverse_condition (code)
3139 enum rtx_code code;
3140 {
3141 switch (code)
3142 {
3143 case EQ:
3144 return NE;
3145
3146 case NE:
3147 return EQ;
3148
3149 case GT:
3150 return LE;
3151
3152 case GE:
3153 return LT;
3154
3155 case LT:
3156 return GE;
3157
3158 case LE:
3159 return GT;
3160
3161 case GTU:
3162 return LEU;
3163
3164 case GEU:
3165 return LTU;
3166
3167 case LTU:
3168 return GEU;
3169
3170 case LEU:
3171 return GTU;
3172
3173 default:
3174 abort ();
3175 return UNKNOWN;
3176 }
3177 }
3178
3179 /* Similar, but return the code when two operands of a comparison are swapped.
3180 This IS safe for IEEE floating-point. */
3181
3182 enum rtx_code
3183 swap_condition (code)
3184 enum rtx_code code;
3185 {
3186 switch (code)
3187 {
3188 case EQ:
3189 case NE:
3190 return code;
3191
3192 case GT:
3193 return LT;
3194
3195 case GE:
3196 return LE;
3197
3198 case LT:
3199 return GT;
3200
3201 case LE:
3202 return GE;
3203
3204 case GTU:
3205 return LTU;
3206
3207 case GEU:
3208 return LEU;
3209
3210 case LTU:
3211 return GTU;
3212
3213 case LEU:
3214 return GEU;
3215
3216 default:
3217 abort ();
3218 return UNKNOWN;
3219 }
3220 }
3221
3222 /* Given a comparison CODE, return the corresponding unsigned comparison.
3223 If CODE is an equality comparison or already an unsigned comparison,
3224 CODE is returned. */
3225
3226 enum rtx_code
3227 unsigned_condition (code)
3228 enum rtx_code code;
3229 {
3230 switch (code)
3231 {
3232 case EQ:
3233 case NE:
3234 case GTU:
3235 case GEU:
3236 case LTU:
3237 case LEU:
3238 return code;
3239
3240 case GT:
3241 return GTU;
3242
3243 case GE:
3244 return GEU;
3245
3246 case LT:
3247 return LTU;
3248
3249 case LE:
3250 return LEU;
3251
3252 default:
3253 abort ();
3254 }
3255 }
3256
3257 /* Similarly, return the signed version of a comparison. */
3258
3259 enum rtx_code
3260 signed_condition (code)
3261 enum rtx_code code;
3262 {
3263 switch (code)
3264 {
3265 case EQ:
3266 case NE:
3267 case GT:
3268 case GE:
3269 case LT:
3270 case LE:
3271 return code;
3272
3273 case GTU:
3274 return GT;
3275
3276 case GEU:
3277 return GE;
3278
3279 case LTU:
3280 return LT;
3281
3282 case LEU:
3283 return LE;
3284
3285 default:
3286 abort ();
3287 }
3288 }
3289 \f
3290 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3291 truth of CODE1 implies the truth of CODE2. */
3292
3293 int
3294 comparison_dominates_p (code1, code2)
3295 enum rtx_code code1, code2;
3296 {
3297 if (code1 == code2)
3298 return 1;
3299
3300 switch (code1)
3301 {
3302 case EQ:
3303 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3304 return 1;
3305 break;
3306
3307 case LT:
3308 if (code2 == LE || code2 == NE)
3309 return 1;
3310 break;
3311
3312 case GT:
3313 if (code2 == GE || code2 == NE)
3314 return 1;
3315 break;
3316
3317 case LTU:
3318 if (code2 == LEU || code2 == NE)
3319 return 1;
3320 break;
3321
3322 case GTU:
3323 if (code2 == GEU || code2 == NE)
3324 return 1;
3325 break;
3326
3327 default:
3328 break;
3329 }
3330
3331 return 0;
3332 }
3333 \f
3334 /* Return 1 if INSN is an unconditional jump and nothing else. */
3335
3336 int
3337 simplejump_p (insn)
3338 rtx insn;
3339 {
3340 return (GET_CODE (insn) == JUMP_INSN
3341 && GET_CODE (PATTERN (insn)) == SET
3342 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3343 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3344 }
3345
3346 /* Return nonzero if INSN is a (possibly) conditional jump
3347 and nothing more. */
3348
3349 int
3350 condjump_p (insn)
3351 rtx insn;
3352 {
3353 register rtx x = PATTERN (insn);
3354 if (GET_CODE (x) != SET)
3355 return 0;
3356 if (GET_CODE (SET_DEST (x)) != PC)
3357 return 0;
3358 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3359 return 1;
3360 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3361 return 0;
3362 if (XEXP (SET_SRC (x), 2) == pc_rtx
3363 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3364 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3365 return 1;
3366 if (XEXP (SET_SRC (x), 1) == pc_rtx
3367 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3368 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3369 return 1;
3370 return 0;
3371 }
3372
3373 /* Return nonzero if INSN is a (possibly) conditional jump
3374 and nothing more. */
3375
3376 int
3377 condjump_in_parallel_p (insn)
3378 rtx insn;
3379 {
3380 register rtx x = PATTERN (insn);
3381
3382 if (GET_CODE (x) != PARALLEL)
3383 return 0;
3384 else
3385 x = XVECEXP (x, 0, 0);
3386
3387 if (GET_CODE (x) != SET)
3388 return 0;
3389 if (GET_CODE (SET_DEST (x)) != PC)
3390 return 0;
3391 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3392 return 1;
3393 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3394 return 0;
3395 if (XEXP (SET_SRC (x), 2) == pc_rtx
3396 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3397 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3398 return 1;
3399 if (XEXP (SET_SRC (x), 1) == pc_rtx
3400 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3401 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3402 return 1;
3403 return 0;
3404 }
3405
3406 /* Return the label of a conditional jump. */
3407
3408 rtx
3409 condjump_label (insn)
3410 rtx insn;
3411 {
3412 register rtx x = PATTERN (insn);
3413
3414 if (GET_CODE (x) == PARALLEL)
3415 x = XVECEXP (x, 0, 0);
3416 if (GET_CODE (x) != SET)
3417 return NULL_RTX;
3418 if (GET_CODE (SET_DEST (x)) != PC)
3419 return NULL_RTX;
3420 x = SET_SRC (x);
3421 if (GET_CODE (x) == LABEL_REF)
3422 return x;
3423 if (GET_CODE (x) != IF_THEN_ELSE)
3424 return NULL_RTX;
3425 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
3426 return XEXP (x, 1);
3427 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
3428 return XEXP (x, 2);
3429 return NULL_RTX;
3430 }
3431
3432 #ifdef HAVE_cc0
3433
3434 /* Return 1 if X is an RTX that does nothing but set the condition codes
3435 and CLOBBER or USE registers.
3436 Return -1 if X does explicitly set the condition codes,
3437 but also does other things. */
3438
3439 int
3440 sets_cc0_p (x)
3441 rtx x ATTRIBUTE_UNUSED;
3442 {
3443 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3444 return 1;
3445 if (GET_CODE (x) == PARALLEL)
3446 {
3447 int i;
3448 int sets_cc0 = 0;
3449 int other_things = 0;
3450 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3451 {
3452 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3453 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3454 sets_cc0 = 1;
3455 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3456 other_things = 1;
3457 }
3458 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3459 }
3460 return 0;
3461 }
3462 #endif
3463 \f
3464 /* Follow any unconditional jump at LABEL;
3465 return the ultimate label reached by any such chain of jumps.
3466 If LABEL is not followed by a jump, return LABEL.
3467 If the chain loops or we can't find end, return LABEL,
3468 since that tells caller to avoid changing the insn.
3469
3470 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3471 a USE or CLOBBER. */
3472
3473 rtx
3474 follow_jumps (label)
3475 rtx label;
3476 {
3477 register rtx insn;
3478 register rtx next;
3479 register rtx value = label;
3480 register int depth;
3481
3482 for (depth = 0;
3483 (depth < 10
3484 && (insn = next_active_insn (value)) != 0
3485 && GET_CODE (insn) == JUMP_INSN
3486 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3487 || GET_CODE (PATTERN (insn)) == RETURN)
3488 && (next = NEXT_INSN (insn))
3489 && GET_CODE (next) == BARRIER);
3490 depth++)
3491 {
3492 /* Don't chain through the insn that jumps into a loop
3493 from outside the loop,
3494 since that would create multiple loop entry jumps
3495 and prevent loop optimization. */
3496 rtx tem;
3497 if (!reload_completed)
3498 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3499 if (GET_CODE (tem) == NOTE
3500 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3501 /* ??? Optional. Disables some optimizations, but makes
3502 gcov output more accurate with -O. */
3503 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3504 return value;
3505
3506 /* If we have found a cycle, make the insn jump to itself. */
3507 if (JUMP_LABEL (insn) == label)
3508 return label;
3509
3510 tem = next_active_insn (JUMP_LABEL (insn));
3511 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3512 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3513 break;
3514
3515 value = JUMP_LABEL (insn);
3516 }
3517 if (depth == 10)
3518 return label;
3519 return value;
3520 }
3521
3522 /* Assuming that field IDX of X is a vector of label_refs,
3523 replace each of them by the ultimate label reached by it.
3524 Return nonzero if a change is made.
3525 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3526
3527 static int
3528 tension_vector_labels (x, idx)
3529 register rtx x;
3530 register int idx;
3531 {
3532 int changed = 0;
3533 register int i;
3534 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3535 {
3536 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3537 register rtx nlabel = follow_jumps (olabel);
3538 if (nlabel && nlabel != olabel)
3539 {
3540 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3541 ++LABEL_NUSES (nlabel);
3542 if (--LABEL_NUSES (olabel) == 0)
3543 delete_insn (olabel);
3544 changed = 1;
3545 }
3546 }
3547 return changed;
3548 }
3549 \f
3550 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3551 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3552 in INSN, then store one of them in JUMP_LABEL (INSN).
3553 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3554 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3555 Also, when there are consecutive labels, canonicalize on the last of them.
3556
3557 Note that two labels separated by a loop-beginning note
3558 must be kept distinct if we have not yet done loop-optimization,
3559 because the gap between them is where loop-optimize
3560 will want to move invariant code to. CROSS_JUMP tells us
3561 that loop-optimization is done with.
3562
3563 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3564 two labels distinct if they are separated by only USE or CLOBBER insns. */
3565
3566 static void
3567 mark_jump_label (x, insn, cross_jump)
3568 register rtx x;
3569 rtx insn;
3570 int cross_jump;
3571 {
3572 register RTX_CODE code = GET_CODE (x);
3573 register int i;
3574 register char *fmt;
3575
3576 switch (code)
3577 {
3578 case PC:
3579 case CC0:
3580 case REG:
3581 case SUBREG:
3582 case CONST_INT:
3583 case SYMBOL_REF:
3584 case CONST_DOUBLE:
3585 case CLOBBER:
3586 case CALL:
3587 return;
3588
3589 case MEM:
3590 /* If this is a constant-pool reference, see if it is a label. */
3591 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3592 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3593 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3594 break;
3595
3596 case LABEL_REF:
3597 {
3598 rtx label = XEXP (x, 0);
3599 rtx olabel = label;
3600 rtx note;
3601 rtx next;
3602
3603 if (GET_CODE (label) != CODE_LABEL)
3604 abort ();
3605
3606 /* Ignore references to labels of containing functions. */
3607 if (LABEL_REF_NONLOCAL_P (x))
3608 break;
3609
3610 /* If there are other labels following this one,
3611 replace it with the last of the consecutive labels. */
3612 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3613 {
3614 if (GET_CODE (next) == CODE_LABEL)
3615 label = next;
3616 else if (cross_jump && GET_CODE (next) == INSN
3617 && (GET_CODE (PATTERN (next)) == USE
3618 || GET_CODE (PATTERN (next)) == CLOBBER))
3619 continue;
3620 else if (GET_CODE (next) != NOTE)
3621 break;
3622 else if (! cross_jump
3623 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3624 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3625 /* ??? Optional. Disables some optimizations, but
3626 makes gcov output more accurate with -O. */
3627 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3628 break;
3629 }
3630
3631 XEXP (x, 0) = label;
3632 if (! insn || ! INSN_DELETED_P (insn))
3633 ++LABEL_NUSES (label);
3634
3635 if (insn)
3636 {
3637 if (GET_CODE (insn) == JUMP_INSN)
3638 JUMP_LABEL (insn) = label;
3639
3640 /* If we've changed OLABEL and we had a REG_LABEL note
3641 for it, update it as well. */
3642 else if (label != olabel
3643 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3644 XEXP (note, 0) = label;
3645
3646 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3647 is one. */
3648 else if (! find_reg_note (insn, REG_LABEL, label))
3649 {
3650 /* This code used to ignore labels which refered to dispatch
3651 tables to avoid flow.c generating worse code.
3652
3653 However, in the presense of global optimizations like
3654 gcse which call find_basic_blocks without calling
3655 life_analysis, not recording such labels will lead
3656 to compiler aborts because of inconsistencies in the
3657 flow graph. So we go ahead and record the label.
3658
3659 It may also be the case that the optimization argument
3660 is no longer valid because of the more accurate cfg
3661 we build in find_basic_blocks -- it no longer pessimizes
3662 code when it finds a REG_LABEL note. */
3663 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
3664 REG_NOTES (insn));
3665 }
3666 }
3667 return;
3668 }
3669
3670 /* Do walk the labels in a vector, but not the first operand of an
3671 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3672 case ADDR_VEC:
3673 case ADDR_DIFF_VEC:
3674 if (! INSN_DELETED_P (insn))
3675 {
3676 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3677
3678 for (i = 0; i < XVECLEN (x, eltnum); i++)
3679 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3680 }
3681 return;
3682
3683 default:
3684 break;
3685 }
3686
3687 fmt = GET_RTX_FORMAT (code);
3688 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3689 {
3690 if (fmt[i] == 'e')
3691 mark_jump_label (XEXP (x, i), insn, cross_jump);
3692 else if (fmt[i] == 'E')
3693 {
3694 register int j;
3695 for (j = 0; j < XVECLEN (x, i); j++)
3696 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3697 }
3698 }
3699 }
3700
3701 /* If all INSN does is set the pc, delete it,
3702 and delete the insn that set the condition codes for it
3703 if that's what the previous thing was. */
3704
3705 void
3706 delete_jump (insn)
3707 rtx insn;
3708 {
3709 register rtx set = single_set (insn);
3710
3711 if (set && GET_CODE (SET_DEST (set)) == PC)
3712 delete_computation (insn);
3713 }
3714
3715 /* Delete INSN and recursively delete insns that compute values used only
3716 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3717 If we are running before flow.c, we need do nothing since flow.c will
3718 delete dead code. We also can't know if the registers being used are
3719 dead or not at this point.
3720
3721 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3722 nothing other than set a register that dies in this insn, we can delete
3723 that insn as well.
3724
3725 On machines with CC0, if CC0 is used in this insn, we may be able to
3726 delete the insn that set it. */
3727
3728 static void
3729 delete_computation (insn)
3730 rtx insn;
3731 {
3732 rtx note, next;
3733
3734 #ifdef HAVE_cc0
3735 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3736 {
3737 rtx prev = prev_nonnote_insn (insn);
3738 /* We assume that at this stage
3739 CC's are always set explicitly
3740 and always immediately before the jump that
3741 will use them. So if the previous insn
3742 exists to set the CC's, delete it
3743 (unless it performs auto-increments, etc.). */
3744 if (prev && GET_CODE (prev) == INSN
3745 && sets_cc0_p (PATTERN (prev)))
3746 {
3747 if (sets_cc0_p (PATTERN (prev)) > 0
3748 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3749 delete_computation (prev);
3750 else
3751 /* Otherwise, show that cc0 won't be used. */
3752 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
3753 cc0_rtx, REG_NOTES (prev));
3754 }
3755 }
3756 #endif
3757
3758 #ifdef INSN_SCHEDULING
3759 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
3760 reload has completed. The schedulers need to be fixed. Until
3761 they are, we must not rely on the death notes here. */
3762 if (reload_completed && flag_schedule_insns_after_reload)
3763 {
3764 delete_insn (insn);
3765 return;
3766 }
3767 #endif
3768
3769 for (note = REG_NOTES (insn); note; note = next)
3770 {
3771 rtx our_prev;
3772
3773 next = XEXP (note, 1);
3774
3775 if (REG_NOTE_KIND (note) != REG_DEAD
3776 /* Verify that the REG_NOTE is legitimate. */
3777 || GET_CODE (XEXP (note, 0)) != REG)
3778 continue;
3779
3780 for (our_prev = prev_nonnote_insn (insn);
3781 our_prev && GET_CODE (our_prev) == INSN;
3782 our_prev = prev_nonnote_insn (our_prev))
3783 {
3784 /* If we reach a SEQUENCE, it is too complex to try to
3785 do anything with it, so give up. */
3786 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3787 break;
3788
3789 if (GET_CODE (PATTERN (our_prev)) == USE
3790 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3791 /* reorg creates USEs that look like this. We leave them
3792 alone because reorg needs them for its own purposes. */
3793 break;
3794
3795 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3796 {
3797 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3798 break;
3799
3800 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3801 {
3802 /* If we find a SET of something else, we can't
3803 delete the insn. */
3804
3805 int i;
3806
3807 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3808 {
3809 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3810
3811 if (GET_CODE (part) == SET
3812 && SET_DEST (part) != XEXP (note, 0))
3813 break;
3814 }
3815
3816 if (i == XVECLEN (PATTERN (our_prev), 0))
3817 delete_computation (our_prev);
3818 }
3819 else if (GET_CODE (PATTERN (our_prev)) == SET
3820 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3821 delete_computation (our_prev);
3822
3823 break;
3824 }
3825
3826 /* If OUR_PREV references the register that dies here, it is an
3827 additional use. Hence any prior SET isn't dead. However, this
3828 insn becomes the new place for the REG_DEAD note. */
3829 if (reg_overlap_mentioned_p (XEXP (note, 0),
3830 PATTERN (our_prev)))
3831 {
3832 XEXP (note, 1) = REG_NOTES (our_prev);
3833 REG_NOTES (our_prev) = note;
3834 break;
3835 }
3836 }
3837 }
3838
3839 delete_insn (insn);
3840 }
3841 \f
3842 /* Delete insn INSN from the chain of insns and update label ref counts.
3843 May delete some following insns as a consequence; may even delete
3844 a label elsewhere and insns that follow it.
3845
3846 Returns the first insn after INSN that was not deleted. */
3847
3848 rtx
3849 delete_insn (insn)
3850 register rtx insn;
3851 {
3852 register rtx next = NEXT_INSN (insn);
3853 register rtx prev = PREV_INSN (insn);
3854 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3855 register int dont_really_delete = 0;
3856
3857 while (next && INSN_DELETED_P (next))
3858 next = NEXT_INSN (next);
3859
3860 /* This insn is already deleted => return first following nondeleted. */
3861 if (INSN_DELETED_P (insn))
3862 return next;
3863
3864 /* Don't delete user-declared labels. Convert them to special NOTEs
3865 instead. */
3866 if (was_code_label && LABEL_NAME (insn) != 0
3867 && optimize && ! dont_really_delete)
3868 {
3869 PUT_CODE (insn, NOTE);
3870 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3871 NOTE_SOURCE_FILE (insn) = 0;
3872 dont_really_delete = 1;
3873 }
3874 else
3875 /* Mark this insn as deleted. */
3876 INSN_DELETED_P (insn) = 1;
3877
3878 /* If this is an unconditional jump, delete it from the jump chain. */
3879 if (simplejump_p (insn))
3880 delete_from_jump_chain (insn);
3881
3882 /* If instruction is followed by a barrier,
3883 delete the barrier too. */
3884
3885 if (next != 0 && GET_CODE (next) == BARRIER)
3886 {
3887 INSN_DELETED_P (next) = 1;
3888 next = NEXT_INSN (next);
3889 }
3890
3891 /* Patch out INSN (and the barrier if any) */
3892
3893 if (optimize && ! dont_really_delete)
3894 {
3895 if (prev)
3896 {
3897 NEXT_INSN (prev) = next;
3898 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3899 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3900 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3901 }
3902
3903 if (next)
3904 {
3905 PREV_INSN (next) = prev;
3906 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3907 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3908 }
3909
3910 if (prev && NEXT_INSN (prev) == 0)
3911 set_last_insn (prev);
3912 }
3913
3914 /* If deleting a jump, decrement the count of the label,
3915 and delete the label if it is now unused. */
3916
3917 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3918 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3919 {
3920 /* This can delete NEXT or PREV,
3921 either directly if NEXT is JUMP_LABEL (INSN),
3922 or indirectly through more levels of jumps. */
3923 delete_insn (JUMP_LABEL (insn));
3924 /* I feel a little doubtful about this loop,
3925 but I see no clean and sure alternative way
3926 to find the first insn after INSN that is not now deleted.
3927 I hope this works. */
3928 while (next && INSN_DELETED_P (next))
3929 next = NEXT_INSN (next);
3930 return next;
3931 }
3932
3933 /* Likewise if we're deleting a dispatch table. */
3934
3935 if (GET_CODE (insn) == JUMP_INSN
3936 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3937 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3938 {
3939 rtx pat = PATTERN (insn);
3940 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3941 int len = XVECLEN (pat, diff_vec_p);
3942
3943 for (i = 0; i < len; i++)
3944 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3945 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3946 while (next && INSN_DELETED_P (next))
3947 next = NEXT_INSN (next);
3948 return next;
3949 }
3950
3951 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3952 prev = PREV_INSN (prev);
3953
3954 /* If INSN was a label and a dispatch table follows it,
3955 delete the dispatch table. The tablejump must have gone already.
3956 It isn't useful to fall through into a table. */
3957
3958 if (was_code_label
3959 && NEXT_INSN (insn) != 0
3960 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3961 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3962 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3963 next = delete_insn (NEXT_INSN (insn));
3964
3965 /* If INSN was a label, delete insns following it if now unreachable. */
3966
3967 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3968 {
3969 register RTX_CODE code;
3970 while (next != 0
3971 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3972 || code == NOTE || code == BARRIER
3973 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3974 {
3975 if (code == NOTE
3976 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3977 next = NEXT_INSN (next);
3978 /* Keep going past other deleted labels to delete what follows. */
3979 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3980 next = NEXT_INSN (next);
3981 else
3982 /* Note: if this deletes a jump, it can cause more
3983 deletion of unreachable code, after a different label.
3984 As long as the value from this recursive call is correct,
3985 this invocation functions correctly. */
3986 next = delete_insn (next);
3987 }
3988 }
3989
3990 return next;
3991 }
3992
3993 /* Advance from INSN till reaching something not deleted
3994 then return that. May return INSN itself. */
3995
3996 rtx
3997 next_nondeleted_insn (insn)
3998 rtx insn;
3999 {
4000 while (INSN_DELETED_P (insn))
4001 insn = NEXT_INSN (insn);
4002 return insn;
4003 }
4004 \f
4005 /* Delete a range of insns from FROM to TO, inclusive.
4006 This is for the sake of peephole optimization, so assume
4007 that whatever these insns do will still be done by a new
4008 peephole insn that will replace them. */
4009
4010 void
4011 delete_for_peephole (from, to)
4012 register rtx from, to;
4013 {
4014 register rtx insn = from;
4015
4016 while (1)
4017 {
4018 register rtx next = NEXT_INSN (insn);
4019 register rtx prev = PREV_INSN (insn);
4020
4021 if (GET_CODE (insn) != NOTE)
4022 {
4023 INSN_DELETED_P (insn) = 1;
4024
4025 /* Patch this insn out of the chain. */
4026 /* We don't do this all at once, because we
4027 must preserve all NOTEs. */
4028 if (prev)
4029 NEXT_INSN (prev) = next;
4030
4031 if (next)
4032 PREV_INSN (next) = prev;
4033 }
4034
4035 if (insn == to)
4036 break;
4037 insn = next;
4038 }
4039
4040 /* Note that if TO is an unconditional jump
4041 we *do not* delete the BARRIER that follows,
4042 since the peephole that replaces this sequence
4043 is also an unconditional jump in that case. */
4044 }
4045 \f
4046 /* Invert the condition of the jump JUMP, and make it jump
4047 to label NLABEL instead of where it jumps now. */
4048
4049 int
4050 invert_jump (jump, nlabel)
4051 rtx jump, nlabel;
4052 {
4053 /* We have to either invert the condition and change the label or
4054 do neither. Either operation could fail. We first try to invert
4055 the jump. If that succeeds, we try changing the label. If that fails,
4056 we invert the jump back to what it was. */
4057
4058 if (! invert_exp (PATTERN (jump), jump))
4059 return 0;
4060
4061 if (redirect_jump (jump, nlabel))
4062 {
4063 if (flag_branch_probabilities)
4064 {
4065 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
4066
4067 /* An inverted jump means that a probability taken becomes a
4068 probability not taken. Subtract the branch probability from the
4069 probability base to convert it back to a taken probability.
4070 (We don't flip the probability on a branch that's never taken. */
4071 if (note && XINT (XEXP (note, 0), 0) >= 0)
4072 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
4073 }
4074
4075 return 1;
4076 }
4077
4078 if (! invert_exp (PATTERN (jump), jump))
4079 /* This should just be putting it back the way it was. */
4080 abort ();
4081
4082 return 0;
4083 }
4084
4085 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4086
4087 Return 1 if we can do so, 0 if we cannot find a way to do so that
4088 matches a pattern. */
4089
4090 int
4091 invert_exp (x, insn)
4092 rtx x;
4093 rtx insn;
4094 {
4095 register RTX_CODE code;
4096 register int i;
4097 register char *fmt;
4098
4099 code = GET_CODE (x);
4100
4101 if (code == IF_THEN_ELSE)
4102 {
4103 register rtx comp = XEXP (x, 0);
4104 register rtx tem;
4105
4106 /* We can do this in two ways: The preferable way, which can only
4107 be done if this is not an integer comparison, is to reverse
4108 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4109 of the IF_THEN_ELSE. If we can't do either, fail. */
4110
4111 if (can_reverse_comparison_p (comp, insn)
4112 && validate_change (insn, &XEXP (x, 0),
4113 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
4114 GET_MODE (comp), XEXP (comp, 0),
4115 XEXP (comp, 1)), 0))
4116 return 1;
4117
4118 tem = XEXP (x, 1);
4119 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
4120 validate_change (insn, &XEXP (x, 2), tem, 1);
4121 return apply_change_group ();
4122 }
4123
4124 fmt = GET_RTX_FORMAT (code);
4125 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4126 {
4127 if (fmt[i] == 'e')
4128 if (! invert_exp (XEXP (x, i), insn))
4129 return 0;
4130 if (fmt[i] == 'E')
4131 {
4132 register int j;
4133 for (j = 0; j < XVECLEN (x, i); j++)
4134 if (!invert_exp (XVECEXP (x, i, j), insn))
4135 return 0;
4136 }
4137 }
4138
4139 return 1;
4140 }
4141 \f
4142 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4143 If the old jump target label is unused as a result,
4144 it and the code following it may be deleted.
4145
4146 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4147 RETURN insn.
4148
4149 The return value will be 1 if the change was made, 0 if it wasn't (this
4150 can only occur for NLABEL == 0). */
4151
4152 int
4153 redirect_jump (jump, nlabel)
4154 rtx jump, nlabel;
4155 {
4156 register rtx olabel = JUMP_LABEL (jump);
4157
4158 if (nlabel == olabel)
4159 return 1;
4160
4161 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
4162 return 0;
4163
4164 /* If this is an unconditional branch, delete it from the jump_chain of
4165 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4166 have UID's in range and JUMP_CHAIN is valid). */
4167 if (jump_chain && (simplejump_p (jump)
4168 || GET_CODE (PATTERN (jump)) == RETURN))
4169 {
4170 int label_index = nlabel ? INSN_UID (nlabel) : 0;
4171
4172 delete_from_jump_chain (jump);
4173 if (label_index < max_jump_chain
4174 && INSN_UID (jump) < max_jump_chain)
4175 {
4176 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
4177 jump_chain[label_index] = jump;
4178 }
4179 }
4180
4181 JUMP_LABEL (jump) = nlabel;
4182 if (nlabel)
4183 ++LABEL_NUSES (nlabel);
4184
4185 if (olabel && --LABEL_NUSES (olabel) == 0)
4186 delete_insn (olabel);
4187
4188 return 1;
4189 }
4190
4191 /* Delete the instruction JUMP from any jump chain it might be on. */
4192
4193 static void
4194 delete_from_jump_chain (jump)
4195 rtx jump;
4196 {
4197 int index;
4198 rtx olabel = JUMP_LABEL (jump);
4199
4200 /* Handle unconditional jumps. */
4201 if (jump_chain && olabel != 0
4202 && INSN_UID (olabel) < max_jump_chain
4203 && simplejump_p (jump))
4204 index = INSN_UID (olabel);
4205 /* Handle return insns. */
4206 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
4207 index = 0;
4208 else return;
4209
4210 if (jump_chain[index] == jump)
4211 jump_chain[index] = jump_chain[INSN_UID (jump)];
4212 else
4213 {
4214 rtx insn;
4215
4216 for (insn = jump_chain[index];
4217 insn != 0;
4218 insn = jump_chain[INSN_UID (insn)])
4219 if (jump_chain[INSN_UID (insn)] == jump)
4220 {
4221 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
4222 break;
4223 }
4224 }
4225 }
4226
4227 /* If NLABEL is nonzero, throughout the rtx at LOC,
4228 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4229 zero, alter (RETURN) to (LABEL_REF NLABEL).
4230
4231 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4232 validity with validate_change. Convert (set (pc) (label_ref olabel))
4233 to (return).
4234
4235 Return 0 if we found a change we would like to make but it is invalid.
4236 Otherwise, return 1. */
4237
4238 int
4239 redirect_exp (loc, olabel, nlabel, insn)
4240 rtx *loc;
4241 rtx olabel, nlabel;
4242 rtx insn;
4243 {
4244 register rtx x = *loc;
4245 register RTX_CODE code = GET_CODE (x);
4246 register int i;
4247 register char *fmt;
4248
4249 if (code == LABEL_REF)
4250 {
4251 if (XEXP (x, 0) == olabel)
4252 {
4253 if (nlabel)
4254 XEXP (x, 0) = nlabel;
4255 else
4256 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4257 return 1;
4258 }
4259 }
4260 else if (code == RETURN && olabel == 0)
4261 {
4262 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4263 if (loc == &PATTERN (insn))
4264 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4265 return validate_change (insn, loc, x, 0);
4266 }
4267
4268 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4269 && GET_CODE (SET_SRC (x)) == LABEL_REF
4270 && XEXP (SET_SRC (x), 0) == olabel)
4271 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4272
4273 fmt = GET_RTX_FORMAT (code);
4274 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4275 {
4276 if (fmt[i] == 'e')
4277 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4278 return 0;
4279 if (fmt[i] == 'E')
4280 {
4281 register int j;
4282 for (j = 0; j < XVECLEN (x, i); j++)
4283 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4284 return 0;
4285 }
4286 }
4287
4288 return 1;
4289 }
4290 \f
4291 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4292
4293 If the old jump target label (before the dispatch table) becomes unused,
4294 it and the dispatch table may be deleted. In that case, find the insn
4295 before the jump references that label and delete it and logical successors
4296 too. */
4297
4298 static void
4299 redirect_tablejump (jump, nlabel)
4300 rtx jump, nlabel;
4301 {
4302 register rtx olabel = JUMP_LABEL (jump);
4303
4304 /* Add this jump to the jump_chain of NLABEL. */
4305 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4306 && INSN_UID (jump) < max_jump_chain)
4307 {
4308 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4309 jump_chain[INSN_UID (nlabel)] = jump;
4310 }
4311
4312 PATTERN (jump) = gen_jump (nlabel);
4313 JUMP_LABEL (jump) = nlabel;
4314 ++LABEL_NUSES (nlabel);
4315 INSN_CODE (jump) = -1;
4316
4317 if (--LABEL_NUSES (olabel) == 0)
4318 {
4319 delete_labelref_insn (jump, olabel, 0);
4320 delete_insn (olabel);
4321 }
4322 }
4323
4324 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4325 If we found one, delete it and then delete this insn if DELETE_THIS is
4326 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4327
4328 static int
4329 delete_labelref_insn (insn, label, delete_this)
4330 rtx insn, label;
4331 int delete_this;
4332 {
4333 int deleted = 0;
4334 rtx link;
4335
4336 if (GET_CODE (insn) != NOTE
4337 && reg_mentioned_p (label, PATTERN (insn)))
4338 {
4339 if (delete_this)
4340 {
4341 delete_insn (insn);
4342 deleted = 1;
4343 }
4344 else
4345 return 1;
4346 }
4347
4348 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4349 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4350 {
4351 if (delete_this)
4352 {
4353 delete_insn (insn);
4354 deleted = 1;
4355 }
4356 else
4357 return 1;
4358 }
4359
4360 return deleted;
4361 }
4362 \f
4363 /* Like rtx_equal_p except that it considers two REGs as equal
4364 if they renumber to the same value and considers two commutative
4365 operations to be the same if the order of the operands has been
4366 reversed.
4367
4368 ??? Addition is not commutative on the PA due to the weird implicit
4369 space register selection rules for memory addresses. Therefore, we
4370 don't consider a + b == b + a.
4371
4372 We could/should make this test a little tighter. Possibly only
4373 disabling it on the PA via some backend macro or only disabling this
4374 case when the PLUS is inside a MEM. */
4375
4376 int
4377 rtx_renumbered_equal_p (x, y)
4378 rtx x, y;
4379 {
4380 register int i;
4381 register RTX_CODE code = GET_CODE (x);
4382 register char *fmt;
4383
4384 if (x == y)
4385 return 1;
4386
4387 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4388 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4389 && GET_CODE (SUBREG_REG (y)) == REG)))
4390 {
4391 int reg_x = -1, reg_y = -1;
4392 int word_x = 0, word_y = 0;
4393
4394 if (GET_MODE (x) != GET_MODE (y))
4395 return 0;
4396
4397 /* If we haven't done any renumbering, don't
4398 make any assumptions. */
4399 if (reg_renumber == 0)
4400 return rtx_equal_p (x, y);
4401
4402 if (code == SUBREG)
4403 {
4404 reg_x = REGNO (SUBREG_REG (x));
4405 word_x = SUBREG_WORD (x);
4406
4407 if (reg_renumber[reg_x] >= 0)
4408 {
4409 reg_x = reg_renumber[reg_x] + word_x;
4410 word_x = 0;
4411 }
4412 }
4413
4414 else
4415 {
4416 reg_x = REGNO (x);
4417 if (reg_renumber[reg_x] >= 0)
4418 reg_x = reg_renumber[reg_x];
4419 }
4420
4421 if (GET_CODE (y) == SUBREG)
4422 {
4423 reg_y = REGNO (SUBREG_REG (y));
4424 word_y = SUBREG_WORD (y);
4425
4426 if (reg_renumber[reg_y] >= 0)
4427 {
4428 reg_y = reg_renumber[reg_y];
4429 word_y = 0;
4430 }
4431 }
4432
4433 else
4434 {
4435 reg_y = REGNO (y);
4436 if (reg_renumber[reg_y] >= 0)
4437 reg_y = reg_renumber[reg_y];
4438 }
4439
4440 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4441 }
4442
4443 /* Now we have disposed of all the cases
4444 in which different rtx codes can match. */
4445 if (code != GET_CODE (y))
4446 return 0;
4447
4448 switch (code)
4449 {
4450 case PC:
4451 case CC0:
4452 case ADDR_VEC:
4453 case ADDR_DIFF_VEC:
4454 return 0;
4455
4456 case CONST_INT:
4457 return INTVAL (x) == INTVAL (y);
4458
4459 case LABEL_REF:
4460 /* We can't assume nonlocal labels have their following insns yet. */
4461 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4462 return XEXP (x, 0) == XEXP (y, 0);
4463
4464 /* Two label-refs are equivalent if they point at labels
4465 in the same position in the instruction stream. */
4466 return (next_real_insn (XEXP (x, 0))
4467 == next_real_insn (XEXP (y, 0)));
4468
4469 case SYMBOL_REF:
4470 return XSTR (x, 0) == XSTR (y, 0);
4471
4472 case CODE_LABEL:
4473 /* If we didn't match EQ equality above, they aren't the same. */
4474 return 0;
4475
4476 default:
4477 break;
4478 }
4479
4480 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4481
4482 if (GET_MODE (x) != GET_MODE (y))
4483 return 0;
4484
4485 /* For commutative operations, the RTX match if the operand match in any
4486 order. Also handle the simple binary and unary cases without a loop.
4487
4488 ??? Don't consider PLUS a commutative operator; see comments above. */
4489 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4490 && code != PLUS)
4491 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4492 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4493 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4494 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4495 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4496 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4497 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4498 else if (GET_RTX_CLASS (code) == '1')
4499 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4500
4501 /* Compare the elements. If any pair of corresponding elements
4502 fail to match, return 0 for the whole things. */
4503
4504 fmt = GET_RTX_FORMAT (code);
4505 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4506 {
4507 register int j;
4508 switch (fmt[i])
4509 {
4510 case 'w':
4511 if (XWINT (x, i) != XWINT (y, i))
4512 return 0;
4513 break;
4514
4515 case 'i':
4516 if (XINT (x, i) != XINT (y, i))
4517 return 0;
4518 break;
4519
4520 case 's':
4521 if (strcmp (XSTR (x, i), XSTR (y, i)))
4522 return 0;
4523 break;
4524
4525 case 'e':
4526 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4527 return 0;
4528 break;
4529
4530 case 'u':
4531 if (XEXP (x, i) != XEXP (y, i))
4532 return 0;
4533 /* fall through. */
4534 case '0':
4535 break;
4536
4537 case 'E':
4538 if (XVECLEN (x, i) != XVECLEN (y, i))
4539 return 0;
4540 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4541 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4542 return 0;
4543 break;
4544
4545 default:
4546 abort ();
4547 }
4548 }
4549 return 1;
4550 }
4551 \f
4552 /* If X is a hard register or equivalent to one or a subregister of one,
4553 return the hard register number. If X is a pseudo register that was not
4554 assigned a hard register, return the pseudo register number. Otherwise,
4555 return -1. Any rtx is valid for X. */
4556
4557 int
4558 true_regnum (x)
4559 rtx x;
4560 {
4561 if (GET_CODE (x) == REG)
4562 {
4563 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4564 return reg_renumber[REGNO (x)];
4565 return REGNO (x);
4566 }
4567 if (GET_CODE (x) == SUBREG)
4568 {
4569 int base = true_regnum (SUBREG_REG (x));
4570 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4571 return SUBREG_WORD (x) + base;
4572 }
4573 return -1;
4574 }
4575 \f
4576 /* Optimize code of the form:
4577
4578 for (x = a[i]; x; ...)
4579 ...
4580 for (x = a[i]; x; ...)
4581 ...
4582 foo:
4583
4584 Loop optimize will change the above code into
4585
4586 if (x = a[i])
4587 for (;;)
4588 { ...; if (! (x = ...)) break; }
4589 if (x = a[i])
4590 for (;;)
4591 { ...; if (! (x = ...)) break; }
4592 foo:
4593
4594 In general, if the first test fails, the program can branch
4595 directly to `foo' and skip the second try which is doomed to fail.
4596 We run this after loop optimization and before flow analysis. */
4597
4598 /* When comparing the insn patterns, we track the fact that different
4599 pseudo-register numbers may have been used in each computation.
4600 The following array stores an equivalence -- same_regs[I] == J means
4601 that pseudo register I was used in the first set of tests in a context
4602 where J was used in the second set. We also count the number of such
4603 pending equivalences. If nonzero, the expressions really aren't the
4604 same. */
4605
4606 static int *same_regs;
4607
4608 static int num_same_regs;
4609
4610 /* Track any registers modified between the target of the first jump and
4611 the second jump. They never compare equal. */
4612
4613 static char *modified_regs;
4614
4615 /* Record if memory was modified. */
4616
4617 static int modified_mem;
4618
4619 /* Called via note_stores on each insn between the target of the first
4620 branch and the second branch. It marks any changed registers. */
4621
4622 static void
4623 mark_modified_reg (dest, x)
4624 rtx dest;
4625 rtx x ATTRIBUTE_UNUSED;
4626 {
4627 int regno, i;
4628
4629 if (GET_CODE (dest) == SUBREG)
4630 dest = SUBREG_REG (dest);
4631
4632 if (GET_CODE (dest) == MEM)
4633 modified_mem = 1;
4634
4635 if (GET_CODE (dest) != REG)
4636 return;
4637
4638 regno = REGNO (dest);
4639 if (regno >= FIRST_PSEUDO_REGISTER)
4640 modified_regs[regno] = 1;
4641 else
4642 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4643 modified_regs[regno + i] = 1;
4644 }
4645
4646 /* F is the first insn in the chain of insns. */
4647
4648 void
4649 thread_jumps (f, max_reg, flag_before_loop)
4650 rtx f;
4651 int max_reg;
4652 int flag_before_loop;
4653 {
4654 /* Basic algorithm is to find a conditional branch,
4655 the label it may branch to, and the branch after
4656 that label. If the two branches test the same condition,
4657 walk back from both branch paths until the insn patterns
4658 differ, or code labels are hit. If we make it back to
4659 the target of the first branch, then we know that the first branch
4660 will either always succeed or always fail depending on the relative
4661 senses of the two branches. So adjust the first branch accordingly
4662 in this case. */
4663
4664 rtx label, b1, b2, t1, t2;
4665 enum rtx_code code1, code2;
4666 rtx b1op0, b1op1, b2op0, b2op1;
4667 int changed = 1;
4668 int i;
4669 int *all_reset;
4670
4671 /* Allocate register tables and quick-reset table. */
4672 modified_regs = (char *) alloca (max_reg * sizeof (char));
4673 same_regs = (int *) alloca (max_reg * sizeof (int));
4674 all_reset = (int *) alloca (max_reg * sizeof (int));
4675 for (i = 0; i < max_reg; i++)
4676 all_reset[i] = -1;
4677
4678 while (changed)
4679 {
4680 changed = 0;
4681
4682 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4683 {
4684 /* Get to a candidate branch insn. */
4685 if (GET_CODE (b1) != JUMP_INSN
4686 || ! condjump_p (b1) || simplejump_p (b1)
4687 || JUMP_LABEL (b1) == 0)
4688 continue;
4689
4690 bzero (modified_regs, max_reg * sizeof (char));
4691 modified_mem = 0;
4692
4693 bcopy ((char *) all_reset, (char *) same_regs,
4694 max_reg * sizeof (int));
4695 num_same_regs = 0;
4696
4697 label = JUMP_LABEL (b1);
4698
4699 /* Look for a branch after the target. Record any registers and
4700 memory modified between the target and the branch. Stop when we
4701 get to a label since we can't know what was changed there. */
4702 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4703 {
4704 if (GET_CODE (b2) == CODE_LABEL)
4705 break;
4706
4707 else if (GET_CODE (b2) == JUMP_INSN)
4708 {
4709 /* If this is an unconditional jump and is the only use of
4710 its target label, we can follow it. */
4711 if (simplejump_p (b2)
4712 && JUMP_LABEL (b2) != 0
4713 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4714 {
4715 b2 = JUMP_LABEL (b2);
4716 continue;
4717 }
4718 else
4719 break;
4720 }
4721
4722 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4723 continue;
4724
4725 if (GET_CODE (b2) == CALL_INSN)
4726 {
4727 modified_mem = 1;
4728 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4729 if (call_used_regs[i] && ! fixed_regs[i]
4730 && i != STACK_POINTER_REGNUM
4731 && i != FRAME_POINTER_REGNUM
4732 && i != HARD_FRAME_POINTER_REGNUM
4733 && i != ARG_POINTER_REGNUM)
4734 modified_regs[i] = 1;
4735 }
4736
4737 note_stores (PATTERN (b2), mark_modified_reg);
4738 }
4739
4740 /* Check the next candidate branch insn from the label
4741 of the first. */
4742 if (b2 == 0
4743 || GET_CODE (b2) != JUMP_INSN
4744 || b2 == b1
4745 || ! condjump_p (b2)
4746 || simplejump_p (b2))
4747 continue;
4748
4749 /* Get the comparison codes and operands, reversing the
4750 codes if appropriate. If we don't have comparison codes,
4751 we can't do anything. */
4752 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4753 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4754 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4755 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4756 code1 = reverse_condition (code1);
4757
4758 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4759 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4760 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4761 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4762 code2 = reverse_condition (code2);
4763
4764 /* If they test the same things and knowing that B1 branches
4765 tells us whether or not B2 branches, check if we
4766 can thread the branch. */
4767 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4768 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4769 && (comparison_dominates_p (code1, code2)
4770 || (comparison_dominates_p (code1, reverse_condition (code2))
4771 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
4772 0),
4773 b1))))
4774 {
4775 t1 = prev_nonnote_insn (b1);
4776 t2 = prev_nonnote_insn (b2);
4777
4778 while (t1 != 0 && t2 != 0)
4779 {
4780 if (t2 == label)
4781 {
4782 /* We have reached the target of the first branch.
4783 If there are no pending register equivalents,
4784 we know that this branch will either always
4785 succeed (if the senses of the two branches are
4786 the same) or always fail (if not). */
4787 rtx new_label;
4788
4789 if (num_same_regs != 0)
4790 break;
4791
4792 if (comparison_dominates_p (code1, code2))
4793 new_label = JUMP_LABEL (b2);
4794 else
4795 new_label = get_label_after (b2);
4796
4797 if (JUMP_LABEL (b1) != new_label)
4798 {
4799 rtx prev = PREV_INSN (new_label);
4800
4801 if (flag_before_loop
4802 && GET_CODE (prev) == NOTE
4803 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4804 {
4805 /* Don't thread to the loop label. If a loop
4806 label is reused, loop optimization will
4807 be disabled for that loop. */
4808 new_label = gen_label_rtx ();
4809 emit_label_after (new_label, PREV_INSN (prev));
4810 }
4811 changed |= redirect_jump (b1, new_label);
4812 }
4813 break;
4814 }
4815
4816 /* If either of these is not a normal insn (it might be
4817 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4818 have already been skipped above.) Similarly, fail
4819 if the insns are different. */
4820 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4821 || recog_memoized (t1) != recog_memoized (t2)
4822 || ! rtx_equal_for_thread_p (PATTERN (t1),
4823 PATTERN (t2), t2))
4824 break;
4825
4826 t1 = prev_nonnote_insn (t1);
4827 t2 = prev_nonnote_insn (t2);
4828 }
4829 }
4830 }
4831 }
4832 }
4833 \f
4834 /* This is like RTX_EQUAL_P except that it knows about our handling of
4835 possibly equivalent registers and knows to consider volatile and
4836 modified objects as not equal.
4837
4838 YINSN is the insn containing Y. */
4839
4840 int
4841 rtx_equal_for_thread_p (x, y, yinsn)
4842 rtx x, y;
4843 rtx yinsn;
4844 {
4845 register int i;
4846 register int j;
4847 register enum rtx_code code;
4848 register char *fmt;
4849
4850 code = GET_CODE (x);
4851 /* Rtx's of different codes cannot be equal. */
4852 if (code != GET_CODE (y))
4853 return 0;
4854
4855 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4856 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4857
4858 if (GET_MODE (x) != GET_MODE (y))
4859 return 0;
4860
4861 /* For floating-point, consider everything unequal. This is a bit
4862 pessimistic, but this pass would only rarely do anything for FP
4863 anyway. */
4864 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4865 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
4866 return 0;
4867
4868 /* For commutative operations, the RTX match if the operand match in any
4869 order. Also handle the simple binary and unary cases without a loop. */
4870 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4871 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4872 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4873 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4874 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4875 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4876 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4877 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4878 else if (GET_RTX_CLASS (code) == '1')
4879 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4880
4881 /* Handle special-cases first. */
4882 switch (code)
4883 {
4884 case REG:
4885 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4886 return 1;
4887
4888 /* If neither is user variable or hard register, check for possible
4889 equivalence. */
4890 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4891 || REGNO (x) < FIRST_PSEUDO_REGISTER
4892 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4893 return 0;
4894
4895 if (same_regs[REGNO (x)] == -1)
4896 {
4897 same_regs[REGNO (x)] = REGNO (y);
4898 num_same_regs++;
4899
4900 /* If this is the first time we are seeing a register on the `Y'
4901 side, see if it is the last use. If not, we can't thread the
4902 jump, so mark it as not equivalent. */
4903 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4904 return 0;
4905
4906 return 1;
4907 }
4908 else
4909 return (same_regs[REGNO (x)] == REGNO (y));
4910
4911 break;
4912
4913 case MEM:
4914 /* If memory modified or either volatile, not equivalent.
4915 Else, check address. */
4916 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4917 return 0;
4918
4919 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4920
4921 case ASM_INPUT:
4922 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4923 return 0;
4924
4925 break;
4926
4927 case SET:
4928 /* Cancel a pending `same_regs' if setting equivalenced registers.
4929 Then process source. */
4930 if (GET_CODE (SET_DEST (x)) == REG
4931 && GET_CODE (SET_DEST (y)) == REG)
4932 {
4933 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4934 {
4935 same_regs[REGNO (SET_DEST (x))] = -1;
4936 num_same_regs--;
4937 }
4938 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4939 return 0;
4940 }
4941 else
4942 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4943 return 0;
4944
4945 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4946
4947 case LABEL_REF:
4948 return XEXP (x, 0) == XEXP (y, 0);
4949
4950 case SYMBOL_REF:
4951 return XSTR (x, 0) == XSTR (y, 0);
4952
4953 default:
4954 break;
4955 }
4956
4957 if (x == y)
4958 return 1;
4959
4960 fmt = GET_RTX_FORMAT (code);
4961 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4962 {
4963 switch (fmt[i])
4964 {
4965 case 'w':
4966 if (XWINT (x, i) != XWINT (y, i))
4967 return 0;
4968 break;
4969
4970 case 'n':
4971 case 'i':
4972 if (XINT (x, i) != XINT (y, i))
4973 return 0;
4974 break;
4975
4976 case 'V':
4977 case 'E':
4978 /* Two vectors must have the same length. */
4979 if (XVECLEN (x, i) != XVECLEN (y, i))
4980 return 0;
4981
4982 /* And the corresponding elements must match. */
4983 for (j = 0; j < XVECLEN (x, i); j++)
4984 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4985 XVECEXP (y, i, j), yinsn) == 0)
4986 return 0;
4987 break;
4988
4989 case 'e':
4990 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4991 return 0;
4992 break;
4993
4994 case 'S':
4995 case 's':
4996 if (strcmp (XSTR (x, i), XSTR (y, i)))
4997 return 0;
4998 break;
4999
5000 case 'u':
5001 /* These are just backpointers, so they don't matter. */
5002 break;
5003
5004 case '0':
5005 break;
5006
5007 /* It is believed that rtx's at this level will never
5008 contain anything but integers and other rtx's,
5009 except for within LABEL_REFs and SYMBOL_REFs. */
5010 default:
5011 abort ();
5012 }
5013 }
5014 return 1;
5015 }
5016 \f
5017
5018 #ifndef HAVE_cc0
5019 /* Return the insn that NEW can be safely inserted in front of starting at
5020 the jump insn INSN. Return 0 if it is not safe to do this jump
5021 optimization. Note that NEW must contain a single set. */
5022
5023 static rtx
5024 find_insert_position (insn, new)
5025 rtx insn;
5026 rtx new;
5027 {
5028 int i;
5029 rtx prev;
5030
5031 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
5032 if (GET_CODE (PATTERN (new)) != PARALLEL)
5033 return insn;
5034
5035 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5036 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5037 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5038 insn))
5039 break;
5040
5041 if (i < 0)
5042 return insn;
5043
5044 /* There is a good chance that the previous insn PREV sets the thing
5045 being clobbered (often the CC in a hard reg). If PREV does not
5046 use what NEW sets, we can insert NEW before PREV. */
5047
5048 prev = prev_active_insn (insn);
5049 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5050 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5051 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5052 insn)
5053 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5054 prev))
5055 return 0;
5056
5057 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
5058 }
5059 #endif /* !HAVE_cc0 */