]> gcc.gnu.org Git - gcc.git/blob - gcc/jump.c
git://gcc.gnu.org / gcc.git / blob
? search:
summary | shortlog | log | commit | commitdiff | tree
blame | history | raw | HEAD
rtlanal.c (regs_set_between_p): New function.
[gcc.git] / gcc / jump.c
1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-97, 1998 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 "recog.h"
63 #include "expr.h"
64 #include "real.h"
65 #include "except.h"
66 #include "toplev.h"
67
68 /* ??? Eventually must record somehow the labels used by jumps
69 from nested functions. */
70 /* Pre-record the next or previous real insn for each label?
71 No, this pass is very fast anyway. */
72 /* Condense consecutive labels?
73 This would make life analysis faster, maybe. */
74 /* Optimize jump y; x: ... y: jumpif... x?
75 Don't know if it is worth bothering with. */
76 /* Optimize two cases of conditional jump to conditional jump?
77 This can never delete any instruction or make anything dead,
78 or even change what is live at any point.
79 So perhaps let combiner do it. */
80
81 /* Vector indexed by uid.
82 For each CODE_LABEL, index by its uid to get first unconditional jump
83 that jumps to the label.
84 For each JUMP_INSN, index by its uid to get the next unconditional jump
85 that jumps to the same label.
86 Element 0 is the start of a chain of all return insns.
87 (It is safe to use element 0 because insn uid 0 is not used. */
88
89 static rtx *jump_chain;
90
91 /* List of labels referred to from initializers.
92 These can never be deleted. */
93 rtx forced_labels;
94
95 /* Maximum index in jump_chain. */
96
97 static int max_jump_chain;
98
99 /* Set nonzero by jump_optimize if control can fall through
100 to the end of the function. */
101 int can_reach_end;
102
103 /* Indicates whether death notes are significant in cross jump analysis.
104 Normally they are not significant, because of A and B jump to C,
105 and R dies in A, it must die in B. But this might not be true after
106 stack register conversion, and we must compare death notes in that
107 case. */
108
109 static int cross_jump_death_matters = 0;
110
111 static int init_label_info PROTO((rtx));
112 static void delete_barrier_successors PROTO((rtx));
113 static void mark_all_labels PROTO((rtx, int));
114 static rtx delete_unreferenced_labels PROTO((rtx));
115 static void delete_noop_moves PROTO((rtx));
116 static int calculate_can_reach_end PROTO((rtx, int, int));
117 static int duplicate_loop_exit_test PROTO((rtx));
118 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
119 static void do_cross_jump PROTO((rtx, rtx, rtx));
120 static int jump_back_p PROTO((rtx, rtx));
121 static int tension_vector_labels PROTO((rtx, int));
122 static void mark_jump_label PROTO((rtx, rtx, int));
123 static void delete_computation PROTO((rtx));
124 static void delete_from_jump_chain PROTO((rtx));
125 static int delete_labelref_insn PROTO((rtx, rtx, int));
126 static void mark_modified_reg PROTO((rtx, rtx));
127 static void redirect_tablejump PROTO((rtx, rtx));
128 #ifndef HAVE_cc0
129 static rtx find_insert_position PROTO((rtx, rtx));
130 #endif
131 \f
132 /* Delete no-op jumps and optimize jumps to jumps
133 and jumps around jumps.
134 Delete unused labels and unreachable code.
135
136 If CROSS_JUMP is 1, detect matching code
137 before a jump and its destination and unify them.
138 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
139
140 If NOOP_MOVES is nonzero, delete no-op move insns.
141
142 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
143 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
144
145 If `optimize' is zero, don't change any code,
146 just determine whether control drops off the end of the function.
147 This case occurs when we have -W and not -O.
148 It works because `delete_insn' checks the value of `optimize'
149 and refrains from actually deleting when that is 0. */
150
151 void
152 jump_optimize (f, cross_jump, noop_moves, after_regscan)
153 rtx f;
154 int cross_jump;
155 int noop_moves;
156 int after_regscan;
157 {
158 register rtx insn, next;
159 int changed;
160 int old_max_reg;
161 int first = 1;
162 int max_uid = 0;
163 rtx last_insn;
164
165 cross_jump_death_matters = (cross_jump == 2);
166 max_uid = init_label_info (f) + 1;
167
168 /* If we are performing cross jump optimizations, then initialize
169 tables mapping UIDs to EH regions to avoid incorrect movement
170 of insns from one EH region to another. */
171 if (flag_exceptions && cross_jump)
172 init_insn_eh_region (f, max_uid);
173
174 delete_barrier_successors (f);
175
176 /* Leave some extra room for labels and duplicate exit test insns
177 we make. */
178 max_jump_chain = max_uid * 14 / 10;
179 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
180 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
181
182 mark_all_labels (f, cross_jump);
183
184 /* Keep track of labels used from static data;
185 they cannot ever be deleted. */
186
187 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
188 LABEL_NUSES (XEXP (insn, 0))++;
189
190 check_exception_handler_labels ();
191
192 /* Keep track of labels used for marking handlers for exception
193 regions; they cannot usually be deleted. */
194
195 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
196 LABEL_NUSES (XEXP (insn, 0))++;
197
198 exception_optimize ();
199
200 last_insn = delete_unreferenced_labels (f);
201
202 if (!optimize)
203 {
204 can_reach_end = calculate_can_reach_end (last_insn, 1, 0);
205
206 /* Zero the "deleted" flag of all the "deleted" insns. */
207 for (insn = f; insn; insn = NEXT_INSN (insn))
208 INSN_DELETED_P (insn) = 0;
209
210 /* Show that the jump chain is not valid. */
211 jump_chain = 0;
212 return;
213 }
214
215 #ifdef HAVE_return
216 if (HAVE_return)
217 {
218 /* If we fall through to the epilogue, see if we can insert a RETURN insn
219 in front of it. If the machine allows it at this point (we might be
220 after reload for a leaf routine), it will improve optimization for it
221 to be there. */
222 insn = get_last_insn ();
223 while (insn && GET_CODE (insn) == NOTE)
224 insn = PREV_INSN (insn);
225
226 if (insn && GET_CODE (insn) != BARRIER)
227 {
228 emit_jump_insn (gen_return ());
229 emit_barrier ();
230 }
231 }
232 #endif
233
234 if (noop_moves)
235 delete_noop_moves (f);
236
237 /* If we haven't yet gotten to reload and we have just run regscan,
238 delete any insn that sets a register that isn't used elsewhere.
239 This helps some of the optimizations below by having less insns
240 being jumped around. */
241
242 if (! reload_completed && after_regscan)
243 for (insn = f; insn; insn = next)
244 {
245 rtx set = single_set (insn);
246
247 next = NEXT_INSN (insn);
248
249 if (set && GET_CODE (SET_DEST (set)) == REG
250 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
251 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
252 /* We use regno_last_note_uid so as not to delete the setting
253 of a reg that's used in notes. A subsequent optimization
254 might arrange to use that reg for real. */
255 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
256 && ! side_effects_p (SET_SRC (set))
257 && ! find_reg_note (insn, REG_RETVAL, 0))
258 delete_insn (insn);
259 }
260
261 /* Now iterate optimizing jumps until nothing changes over one pass. */
262 changed = 1;
263 old_max_reg = max_reg_num ();
264 while (changed)
265 {
266 changed = 0;
267
268 for (insn = f; insn; insn = next)
269 {
270 rtx reallabelprev;
271 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
272 rtx nlabel;
273 int this_is_simplejump, this_is_condjump, reversep = 0;
274 int this_is_condjump_in_parallel;
275
276 #if 0
277 /* If NOT the first iteration, if this is the last jump pass
278 (just before final), do the special peephole optimizations.
279 Avoiding the first iteration gives ordinary jump opts
280 a chance to work before peephole opts. */
281
282 if (reload_completed && !first && !flag_no_peephole)
283 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
284 peephole (insn);
285 #endif
286
287 /* That could have deleted some insns after INSN, so check now
288 what the following insn is. */
289
290 next = NEXT_INSN (insn);
291
292 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
293 jump. Try to optimize by duplicating the loop exit test if so.
294 This is only safe immediately after regscan, because it uses
295 the values of regno_first_uid and regno_last_uid. */
296 if (after_regscan && GET_CODE (insn) == NOTE
297 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
298 && (temp1 = next_nonnote_insn (insn)) != 0
299 && simplejump_p (temp1))
300 {
301 temp = PREV_INSN (insn);
302 if (duplicate_loop_exit_test (insn))
303 {
304 changed = 1;
305 next = NEXT_INSN (temp);
306 continue;
307 }
308 }
309
310 if (GET_CODE (insn) != JUMP_INSN)
311 continue;
312
313 this_is_simplejump = simplejump_p (insn);
314 this_is_condjump = condjump_p (insn);
315 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
316
317 /* Tension the labels in dispatch tables. */
318
319 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
320 changed |= tension_vector_labels (PATTERN (insn), 0);
321 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
322 changed |= tension_vector_labels (PATTERN (insn), 1);
323
324 /* If a dispatch table always goes to the same place,
325 get rid of it and replace the insn that uses it. */
326
327 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
328 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
329 {
330 int i;
331 rtx pat = PATTERN (insn);
332 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
333 int len = XVECLEN (pat, diff_vec_p);
334 rtx dispatch = prev_real_insn (insn);
335
336 for (i = 0; i < len; i++)
337 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
338 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
339 break;
340 if (i == len
341 && dispatch != 0
342 && GET_CODE (dispatch) == JUMP_INSN
343 && JUMP_LABEL (dispatch) != 0
344 /* Don't mess with a casesi insn. */
345 && !(GET_CODE (PATTERN (dispatch)) == SET
346 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
347 == IF_THEN_ELSE))
348 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
349 {
350 redirect_tablejump (dispatch,
351 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
352 changed = 1;
353 }
354 }
355
356 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
357
358 /* If a jump references the end of the function, try to turn
359 it into a RETURN insn, possibly a conditional one. */
360 if (JUMP_LABEL (insn)
361 && (next_active_insn (JUMP_LABEL (insn)) == 0
362 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
363 == RETURN))
364 changed |= redirect_jump (insn, NULL_RTX);
365
366 /* Detect jump to following insn. */
367 if (reallabelprev == insn && condjump_p (insn))
368 {
369 next = next_real_insn (JUMP_LABEL (insn));
370 delete_jump (insn);
371 changed = 1;
372 continue;
373 }
374
375 /* If we have an unconditional jump preceded by a USE, try to put
376 the USE before the target and jump there. This simplifies many
377 of the optimizations below since we don't have to worry about
378 dealing with these USE insns. We only do this if the label
379 being branch to already has the identical USE or if code
380 never falls through to that label. */
381
382 if (this_is_simplejump
383 && (temp = prev_nonnote_insn (insn)) != 0
384 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
385 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
386 && (GET_CODE (temp1) == BARRIER
387 || (GET_CODE (temp1) == INSN
388 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
389 /* Don't do this optimization if we have a loop containing only
390 the USE instruction, and the loop start label has a usage
391 count of 1. This is because we will redo this optimization
392 everytime through the outer loop, and jump opt will never
393 exit. */
394 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
395 && temp2 == JUMP_LABEL (insn)
396 && LABEL_NUSES (temp2) == 1))
397 {
398 if (GET_CODE (temp1) == BARRIER)
399 {
400 emit_insn_after (PATTERN (temp), temp1);
401 temp1 = NEXT_INSN (temp1);
402 }
403
404 delete_insn (temp);
405 redirect_jump (insn, get_label_before (temp1));
406 reallabelprev = prev_real_insn (temp1);
407 changed = 1;
408 }
409
410 /* Simplify if (...) x = a; else x = b; by converting it
411 to x = b; if (...) x = a;
412 if B is sufficiently simple, the test doesn't involve X,
413 and nothing in the test modifies B or X.
414
415 If we have small register classes, we also can't do this if X
416 is a hard register.
417
418 If the "x = b;" insn has any REG_NOTES, we don't do this because
419 of the possibility that we are running after CSE and there is a
420 REG_EQUAL note that is only valid if the branch has already been
421 taken. If we move the insn with the REG_EQUAL note, we may
422 fold the comparison to always be false in a later CSE pass.
423 (We could also delete the REG_NOTES when moving the insn, but it
424 seems simpler to not move it.) An exception is that we can move
425 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
426 value is the same as "b".
427
428 INSN is the branch over the `else' part.
429
430 We set:
431
432 TEMP to the jump insn preceding "x = a;"
433 TEMP1 to X
434 TEMP2 to the insn that sets "x = b;"
435 TEMP3 to the insn that sets "x = a;"
436 TEMP4 to the set of "x = b"; */
437
438 if (this_is_simplejump
439 && (temp3 = prev_active_insn (insn)) != 0
440 && GET_CODE (temp3) == INSN
441 && (temp4 = single_set (temp3)) != 0
442 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
443 && (! SMALL_REGISTER_CLASSES
444 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
445 && (temp2 = next_active_insn (insn)) != 0
446 && GET_CODE (temp2) == INSN
447 && (temp4 = single_set (temp2)) != 0
448 && rtx_equal_p (SET_DEST (temp4), temp1)
449 && ! side_effects_p (SET_SRC (temp4))
450 && ! may_trap_p (SET_SRC (temp4))
451 && (REG_NOTES (temp2) == 0
452 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
453 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
454 && XEXP (REG_NOTES (temp2), 1) == 0
455 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
456 SET_SRC (temp4))))
457 && (temp = prev_active_insn (temp3)) != 0
458 && condjump_p (temp) && ! simplejump_p (temp)
459 /* TEMP must skip over the "x = a;" insn */
460 && prev_real_insn (JUMP_LABEL (temp)) == insn
461 && no_labels_between_p (insn, JUMP_LABEL (temp))
462 /* There must be no other entries to the "x = b;" insn. */
463 && no_labels_between_p (JUMP_LABEL (temp), temp2)
464 /* INSN must either branch to the insn after TEMP2 or the insn
465 after TEMP2 must branch to the same place as INSN. */
466 && (reallabelprev == temp2
467 || ((temp5 = next_active_insn (temp2)) != 0
468 && simplejump_p (temp5)
469 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
470 {
471 /* The test expression, X, may be a complicated test with
472 multiple branches. See if we can find all the uses of
473 the label that TEMP branches to without hitting a CALL_INSN
474 or a jump to somewhere else. */
475 rtx target = JUMP_LABEL (temp);
476 int nuses = LABEL_NUSES (target);
477 rtx p;
478 #ifdef HAVE_cc0
479 rtx q;
480 #endif
481
482 /* Set P to the first jump insn that goes around "x = a;". */
483 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
484 {
485 if (GET_CODE (p) == JUMP_INSN)
486 {
487 if (condjump_p (p) && ! simplejump_p (p)
488 && JUMP_LABEL (p) == target)
489 {
490 nuses--;
491 if (nuses == 0)
492 break;
493 }
494 else
495 break;
496 }
497 else if (GET_CODE (p) == CALL_INSN)
498 break;
499 }
500
501 #ifdef HAVE_cc0
502 /* We cannot insert anything between a set of cc and its use
503 so if P uses cc0, we must back up to the previous insn. */
504 q = prev_nonnote_insn (p);
505 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
506 && sets_cc0_p (PATTERN (q)))
507 p = q;
508 #endif
509
510 if (p)
511 p = PREV_INSN (p);
512
513 /* If we found all the uses and there was no data conflict, we
514 can move the assignment unless we can branch into the middle
515 from somewhere. */
516 if (nuses == 0 && p
517 && no_labels_between_p (p, insn)
518 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
519 && ! reg_set_between_p (temp1, p, temp3)
520 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
521 || ! modified_between_p (SET_SRC (temp4), p, temp2))
522 /* Verify that registers used by the jump are not clobbered
523 by the instruction being moved. */
524 && ! regs_set_between_p (PATTERN (temp), temp2,
525 NEXT_INSN (temp2)))
526 {
527 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
528 delete_insn (temp2);
529
530 /* Set NEXT to an insn that we know won't go away. */
531 next = next_active_insn (insn);
532
533 /* Delete the jump around the set. Note that we must do
534 this before we redirect the test jumps so that it won't
535 delete the code immediately following the assignment
536 we moved (which might be a jump). */
537
538 delete_insn (insn);
539
540 /* We either have two consecutive labels or a jump to
541 a jump, so adjust all the JUMP_INSNs to branch to where
542 INSN branches to. */
543 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
544 if (GET_CODE (p) == JUMP_INSN)
545 redirect_jump (p, target);
546
547 changed = 1;
548 continue;
549 }
550 }
551
552 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
553 to x = a; if (...) goto l; x = b;
554 if A is sufficiently simple, the test doesn't involve X,
555 and nothing in the test modifies A or X.
556
557 If we have small register classes, we also can't do this if X
558 is a hard register.
559
560 If the "x = a;" insn has any REG_NOTES, we don't do this because
561 of the possibility that we are running after CSE and there is a
562 REG_EQUAL note that is only valid if the branch has already been
563 taken. If we move the insn with the REG_EQUAL note, we may
564 fold the comparison to always be false in a later CSE pass.
565 (We could also delete the REG_NOTES when moving the insn, but it
566 seems simpler to not move it.) An exception is that we can move
567 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
568 value is the same as "a".
569
570 INSN is the goto.
571
572 We set:
573
574 TEMP to the jump insn preceding "x = a;"
575 TEMP1 to X
576 TEMP2 to the insn that sets "x = b;"
577 TEMP3 to the insn that sets "x = a;"
578 TEMP4 to the set of "x = a"; */
579
580 if (this_is_simplejump
581 && (temp2 = next_active_insn (insn)) != 0
582 && GET_CODE (temp2) == INSN
583 && (temp4 = single_set (temp2)) != 0
584 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
585 && (! SMALL_REGISTER_CLASSES
586 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
587 && (temp3 = prev_active_insn (insn)) != 0
588 && GET_CODE (temp3) == INSN
589 && (temp4 = single_set (temp3)) != 0
590 && rtx_equal_p (SET_DEST (temp4), temp1)
591 && ! side_effects_p (SET_SRC (temp4))
592 && ! may_trap_p (SET_SRC (temp4))
593 && (REG_NOTES (temp3) == 0
594 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
595 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
596 && XEXP (REG_NOTES (temp3), 1) == 0
597 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
598 SET_SRC (temp4))))
599 && (temp = prev_active_insn (temp3)) != 0
600 && condjump_p (temp) && ! simplejump_p (temp)
601 /* TEMP must skip over the "x = a;" insn */
602 && prev_real_insn (JUMP_LABEL (temp)) == insn
603 && no_labels_between_p (temp, insn))
604 {
605 rtx prev_label = JUMP_LABEL (temp);
606 rtx insert_after = prev_nonnote_insn (temp);
607
608 #ifdef HAVE_cc0
609 /* We cannot insert anything between a set of cc and its use. */
610 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
611 && sets_cc0_p (PATTERN (insert_after)))
612 insert_after = prev_nonnote_insn (insert_after);
613 #endif
614 ++LABEL_NUSES (prev_label);
615
616 if (insert_after
617 && no_labels_between_p (insert_after, temp)
618 && ! reg_referenced_between_p (temp1, insert_after, temp3)
619 && ! reg_referenced_between_p (temp1, temp3,
620 NEXT_INSN (temp2))
621 && ! reg_set_between_p (temp1, insert_after, temp)
622 && ! modified_between_p (SET_SRC (temp4), insert_after, temp)
623 /* Verify that registers used by the jump are not clobbered
624 by the instruction being moved. */
625 && ! regs_set_between_p (PATTERN (temp), temp3,
626 NEXT_INSN (temp3))
627 && invert_jump (temp, JUMP_LABEL (insn)))
628 {
629 emit_insn_after_with_line_notes (PATTERN (temp3),
630 insert_after, temp3);
631 delete_insn (temp3);
632 delete_insn (insn);
633 /* Set NEXT to an insn that we know won't go away. */
634 next = temp2;
635 changed = 1;
636 }
637 if (prev_label && --LABEL_NUSES (prev_label) == 0)
638 delete_insn (prev_label);
639 if (changed)
640 continue;
641 }
642
643 #ifndef HAVE_cc0
644 /* If we have if (...) x = exp; and branches are expensive,
645 EXP is a single insn, does not have any side effects, cannot
646 trap, and is not too costly, convert this to
647 t = exp; if (...) x = t;
648
649 Don't do this when we have CC0 because it is unlikely to help
650 and we'd need to worry about where to place the new insn and
651 the potential for conflicts. We also can't do this when we have
652 notes on the insn for the same reason as above.
653
654 We set:
655
656 TEMP to the "x = exp;" insn.
657 TEMP1 to the single set in the "x = exp;" insn.
658 TEMP2 to "x". */
659
660 if (! reload_completed
661 && this_is_condjump && ! this_is_simplejump
662 && BRANCH_COST >= 3
663 && (temp = next_nonnote_insn (insn)) != 0
664 && GET_CODE (temp) == INSN
665 && REG_NOTES (temp) == 0
666 && (reallabelprev == temp
667 || ((temp2 = next_active_insn (temp)) != 0
668 && simplejump_p (temp2)
669 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
670 && (temp1 = single_set (temp)) != 0
671 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
672 && (! SMALL_REGISTER_CLASSES
673 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
674 && GET_CODE (SET_SRC (temp1)) != REG
675 && GET_CODE (SET_SRC (temp1)) != SUBREG
676 && GET_CODE (SET_SRC (temp1)) != CONST_INT
677 && ! side_effects_p (SET_SRC (temp1))
678 && ! may_trap_p (SET_SRC (temp1))
679 && rtx_cost (SET_SRC (temp1), SET) < 10)
680 {
681 rtx new = gen_reg_rtx (GET_MODE (temp2));
682
683 if ((temp3 = find_insert_position (insn, temp))
684 && validate_change (temp, &SET_DEST (temp1), new, 0))
685 {
686 next = emit_insn_after (gen_move_insn (temp2, new), insn);
687 emit_insn_after_with_line_notes (PATTERN (temp),
688 PREV_INSN (temp3), temp);
689 delete_insn (temp);
690 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
691
692 if (after_regscan)
693 {
694 reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
695 old_max_reg = max_reg_num ();
696 }
697 }
698 }
699
700 /* Similarly, if it takes two insns to compute EXP but they
701 have the same destination. Here TEMP3 will be the second
702 insn and TEMP4 the SET from that insn. */
703
704 if (! reload_completed
705 && this_is_condjump && ! this_is_simplejump
706 && BRANCH_COST >= 4
707 && (temp = next_nonnote_insn (insn)) != 0
708 && GET_CODE (temp) == INSN
709 && REG_NOTES (temp) == 0
710 && (temp3 = next_nonnote_insn (temp)) != 0
711 && GET_CODE (temp3) == INSN
712 && REG_NOTES (temp3) == 0
713 && (reallabelprev == temp3
714 || ((temp2 = next_active_insn (temp3)) != 0
715 && simplejump_p (temp2)
716 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
717 && (temp1 = single_set (temp)) != 0
718 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
719 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
720 && (! SMALL_REGISTER_CLASSES
721 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
722 && ! side_effects_p (SET_SRC (temp1))
723 && ! may_trap_p (SET_SRC (temp1))
724 && rtx_cost (SET_SRC (temp1), SET) < 10
725 && (temp4 = single_set (temp3)) != 0
726 && rtx_equal_p (SET_DEST (temp4), temp2)
727 && ! side_effects_p (SET_SRC (temp4))
728 && ! may_trap_p (SET_SRC (temp4))
729 && rtx_cost (SET_SRC (temp4), SET) < 10)
730 {
731 rtx new = gen_reg_rtx (GET_MODE (temp2));
732
733 if ((temp5 = find_insert_position (insn, temp))
734 && (temp6 = find_insert_position (insn, temp3))
735 && validate_change (temp, &SET_DEST (temp1), new, 0))
736 {
737 /* Use the earliest of temp5 and temp6. */
738 if (temp5 != insn)
739 temp6 = temp5;
740 next = emit_insn_after (gen_move_insn (temp2, new), insn);
741 emit_insn_after_with_line_notes (PATTERN (temp),
742 PREV_INSN (temp6), temp);
743 emit_insn_after_with_line_notes
744 (replace_rtx (PATTERN (temp3), temp2, new),
745 PREV_INSN (temp6), temp3);
746 delete_insn (temp);
747 delete_insn (temp3);
748 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
749
750 if (after_regscan)
751 {
752 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
753 old_max_reg = max_reg_num ();
754 }
755 }
756 }
757
758 /* Finally, handle the case where two insns are used to
759 compute EXP but a temporary register is used. Here we must
760 ensure that the temporary register is not used anywhere else. */
761
762 if (! reload_completed
763 && after_regscan
764 && this_is_condjump && ! this_is_simplejump
765 && BRANCH_COST >= 4
766 && (temp = next_nonnote_insn (insn)) != 0
767 && GET_CODE (temp) == INSN
768 && REG_NOTES (temp) == 0
769 && (temp3 = next_nonnote_insn (temp)) != 0
770 && GET_CODE (temp3) == INSN
771 && REG_NOTES (temp3) == 0
772 && (reallabelprev == temp3
773 || ((temp2 = next_active_insn (temp3)) != 0
774 && simplejump_p (temp2)
775 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
776 && (temp1 = single_set (temp)) != 0
777 && (temp5 = SET_DEST (temp1),
778 (GET_CODE (temp5) == REG
779 || (GET_CODE (temp5) == SUBREG
780 && (temp5 = SUBREG_REG (temp5),
781 GET_CODE (temp5) == REG))))
782 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
783 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
784 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
785 && ! side_effects_p (SET_SRC (temp1))
786 && ! may_trap_p (SET_SRC (temp1))
787 && rtx_cost (SET_SRC (temp1), SET) < 10
788 && (temp4 = single_set (temp3)) != 0
789 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
790 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
791 && (! SMALL_REGISTER_CLASSES
792 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
793 && rtx_equal_p (SET_DEST (temp4), temp2)
794 && ! side_effects_p (SET_SRC (temp4))
795 && ! may_trap_p (SET_SRC (temp4))
796 && rtx_cost (SET_SRC (temp4), SET) < 10)
797 {
798 rtx new = gen_reg_rtx (GET_MODE (temp2));
799
800 if ((temp5 = find_insert_position (insn, temp))
801 && (temp6 = find_insert_position (insn, temp3))
802 && validate_change (temp3, &SET_DEST (temp4), new, 0))
803 {
804 /* Use the earliest of temp5 and temp6. */
805 if (temp5 != insn)
806 temp6 = temp5;
807 next = emit_insn_after (gen_move_insn (temp2, new), insn);
808 emit_insn_after_with_line_notes (PATTERN (temp),
809 PREV_INSN (temp6), temp);
810 emit_insn_after_with_line_notes (PATTERN (temp3),
811 PREV_INSN (temp6), temp3);
812 delete_insn (temp);
813 delete_insn (temp3);
814 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
815
816 if (after_regscan)
817 {
818 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
819 old_max_reg = max_reg_num ();
820 }
821 }
822 }
823 #endif /* HAVE_cc0 */
824
825 /* Try to use a conditional move (if the target has them), or a
826 store-flag insn. The general case is:
827
828 1) x = a; if (...) x = b; and
829 2) if (...) x = b;
830
831 If the jump would be faster, the machine should not have defined
832 the movcc or scc insns!. These cases are often made by the
833 previous optimization.
834
835 The second case is treated as x = x; if (...) x = b;.
836
837 INSN here is the jump around the store. We set:
838
839 TEMP to the "x = b;" insn.
840 TEMP1 to X.
841 TEMP2 to B.
842 TEMP3 to A (X in the second case).
843 TEMP4 to the condition being tested.
844 TEMP5 to the earliest insn used to find the condition. */
845
846 if (/* We can't do this after reload has completed. */
847 ! reload_completed
848 && this_is_condjump && ! this_is_simplejump
849 /* Set TEMP to the "x = b;" insn. */
850 && (temp = next_nonnote_insn (insn)) != 0
851 && GET_CODE (temp) == INSN
852 && GET_CODE (PATTERN (temp)) == SET
853 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
854 && (! SMALL_REGISTER_CLASSES
855 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
856 && ! side_effects_p (temp2 = SET_SRC (PATTERN (temp)))
857 && ! may_trap_p (temp2)
858 /* Allow either form, but prefer the former if both apply.
859 There is no point in using the old value of TEMP1 if
860 it is a register, since cse will alias them. It can
861 lose if the old value were a hard register since CSE
862 won't replace hard registers. Avoid using TEMP3 if
863 small register classes and it is a hard register. */
864 && (((temp3 = reg_set_last (temp1, insn)) != 0
865 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
866 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
867 /* Make the latter case look like x = x; if (...) x = b; */
868 || (temp3 = temp1, 1))
869 /* INSN must either branch to the insn after TEMP or the insn
870 after TEMP must branch to the same place as INSN. */
871 && (reallabelprev == temp
872 || ((temp4 = next_active_insn (temp)) != 0
873 && simplejump_p (temp4)
874 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
875 && (temp4 = get_condition (insn, &temp5)) != 0
876 /* We must be comparing objects whose modes imply the size.
877 We could handle BLKmode if (1) emit_store_flag could
878 and (2) we could find the size reliably. */
879 && GET_MODE (XEXP (temp4, 0)) != BLKmode
880 /* Even if branches are cheap, the store_flag optimization
881 can win when the operation to be performed can be
882 expressed directly. */
883 #ifdef HAVE_cc0
884 /* If the previous insn sets CC0 and something else, we can't
885 do this since we are going to delete that insn. */
886
887 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
888 && GET_CODE (temp6) == INSN
889 && (sets_cc0_p (PATTERN (temp6)) == -1
890 || (sets_cc0_p (PATTERN (temp6)) == 1
891 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
892 #endif
893 )
894 {
895 #ifdef HAVE_conditional_move
896 /* First try a conditional move. */
897 {
898 enum rtx_code code = GET_CODE (temp4);
899 rtx var = temp1;
900 rtx cond0, cond1, aval, bval;
901 rtx target;
902
903 /* Copy the compared variables into cond0 and cond1, so that
904 any side effects performed in or after the old comparison,
905 will not affect our compare which will come later. */
906 /* ??? Is it possible to just use the comparison in the jump
907 insn? After all, we're going to delete it. We'd have
908 to modify emit_conditional_move to take a comparison rtx
909 instead or write a new function. */
910 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
911 /* We want the target to be able to simplify comparisons with
912 zero (and maybe other constants as well), so don't create
913 pseudos for them. There's no need to either. */
914 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
915 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
916 cond1 = XEXP (temp4, 1);
917 else
918 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
919
920 aval = temp3;
921 bval = temp2;
922
923 start_sequence ();
924 target = emit_conditional_move (var, code,
925 cond0, cond1, VOIDmode,
926 aval, bval, GET_MODE (var),
927 (code == LTU || code == GEU
928 || code == LEU || code == GTU));
929
930 if (target)
931 {
932 rtx seq1,seq2,last;
933
934 /* Save the conditional move sequence but don't emit it
935 yet. On some machines, like the alpha, it is possible
936 that temp5 == insn, so next generate the sequence that
937 saves the compared values and then emit both
938 sequences ensuring seq1 occurs before seq2. */
939 seq2 = get_insns ();
940 end_sequence ();
941
942 /* Now that we can't fail, generate the copy insns that
943 preserve the compared values. */
944 start_sequence ();
945 emit_move_insn (cond0, XEXP (temp4, 0));
946 if (cond1 != XEXP (temp4, 1))
947 emit_move_insn (cond1, XEXP (temp4, 1));
948 seq1 = get_insns ();
949 end_sequence ();
950
951 emit_insns_before (seq1, temp5);
952 /* Insert conditional move after insn, to be sure that
953 the jump and a possible compare won't be separated */
954 last = emit_insns_after (seq2, insn);
955
956 /* ??? We can also delete the insn that sets X to A.
957 Flow will do it too though. */
958 delete_insn (temp);
959 next = NEXT_INSN (insn);
960 delete_jump (insn);
961
962 if (after_regscan)
963 {
964 reg_scan_update (seq1, NEXT_INSN (last), old_max_reg);
965 old_max_reg = max_reg_num ();
966 }
967
968 changed = 1;
969 continue;
970 }
971 else
972 end_sequence ();
973 }
974 #endif
975
976 /* That didn't work, try a store-flag insn.
977
978 We further divide the cases into:
979
980 1) x = a; if (...) x = b; and either A or B is zero,
981 2) if (...) x = 0; and jumps are expensive,
982 3) x = a; if (...) x = b; and A and B are constants where all
983 the set bits in A are also set in B and jumps are expensive,
984 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
985 more expensive, and
986 5) if (...) x = b; if jumps are even more expensive. */
987
988 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
989 && ((GET_CODE (temp3) == CONST_INT)
990 /* Make the latter case look like
991 x = x; if (...) x = 0; */
992 || (temp3 = temp1,
993 ((BRANCH_COST >= 2
994 && temp2 == const0_rtx)
995 || BRANCH_COST >= 3)))
996 /* If B is zero, OK; if A is zero, can only do (1) if we
997 can reverse the condition. See if (3) applies possibly
998 by reversing the condition. Prefer reversing to (4) when
999 branches are very expensive. */
1000 && (((BRANCH_COST >= 2
1001 || STORE_FLAG_VALUE == -1
1002 || (STORE_FLAG_VALUE == 1
1003 /* Check that the mask is a power of two,
1004 so that it can probably be generated
1005 with a shift. */
1006 && GET_CODE (temp3) == CONST_INT
1007 && exact_log2 (INTVAL (temp3)) >= 0))
1008 && (reversep = 0, temp2 == const0_rtx))
1009 || ((BRANCH_COST >= 2
1010 || STORE_FLAG_VALUE == -1
1011 || (STORE_FLAG_VALUE == 1
1012 && GET_CODE (temp2) == CONST_INT
1013 && exact_log2 (INTVAL (temp2)) >= 0))
1014 && temp3 == const0_rtx
1015 && (reversep = can_reverse_comparison_p (temp4, insn)))
1016 || (BRANCH_COST >= 2
1017 && GET_CODE (temp2) == CONST_INT
1018 && GET_CODE (temp3) == CONST_INT
1019 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1020 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1021 && (reversep = can_reverse_comparison_p (temp4,
1022 insn)))))
1023 || BRANCH_COST >= 3)
1024 )
1025 {
1026 enum rtx_code code = GET_CODE (temp4);
1027 rtx uval, cval, var = temp1;
1028 int normalizep;
1029 rtx target;
1030
1031 /* If necessary, reverse the condition. */
1032 if (reversep)
1033 code = reverse_condition (code), uval = temp2, cval = temp3;
1034 else
1035 uval = temp3, cval = temp2;
1036
1037 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1038 is the constant 1, it is best to just compute the result
1039 directly. If UVAL is constant and STORE_FLAG_VALUE
1040 includes all of its bits, it is best to compute the flag
1041 value unnormalized and `and' it with UVAL. Otherwise,
1042 normalize to -1 and `and' with UVAL. */
1043 normalizep = (cval != const0_rtx ? -1
1044 : (uval == const1_rtx ? 1
1045 : (GET_CODE (uval) == CONST_INT
1046 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1047 ? 0 : -1));
1048
1049 /* We will be putting the store-flag insn immediately in
1050 front of the comparison that was originally being done,
1051 so we know all the variables in TEMP4 will be valid.
1052 However, this might be in front of the assignment of
1053 A to VAR. If it is, it would clobber the store-flag
1054 we will be emitting.
1055
1056 Therefore, emit into a temporary which will be copied to
1057 VAR immediately after TEMP. */
1058
1059 start_sequence ();
1060 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1061 XEXP (temp4, 0), XEXP (temp4, 1),
1062 VOIDmode,
1063 (code == LTU || code == LEU
1064 || code == GEU || code == GTU),
1065 normalizep);
1066 if (target)
1067 {
1068 rtx seq;
1069 rtx before = insn;
1070
1071 seq = get_insns ();
1072 end_sequence ();
1073
1074 /* Put the store-flag insns in front of the first insn
1075 used to compute the condition to ensure that we
1076 use the same values of them as the current
1077 comparison. However, the remainder of the insns we
1078 generate will be placed directly in front of the
1079 jump insn, in case any of the pseudos we use
1080 are modified earlier. */
1081
1082 emit_insns_before (seq, temp5);
1083
1084 start_sequence ();
1085
1086 /* Both CVAL and UVAL are non-zero. */
1087 if (cval != const0_rtx && uval != const0_rtx)
1088 {
1089 rtx tem1, tem2;
1090
1091 tem1 = expand_and (uval, target, NULL_RTX);
1092 if (GET_CODE (cval) == CONST_INT
1093 && GET_CODE (uval) == CONST_INT
1094 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1095 tem2 = cval;
1096 else
1097 {
1098 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1099 target, NULL_RTX, 0);
1100 tem2 = expand_and (cval, tem2,
1101 (GET_CODE (tem2) == REG
1102 ? tem2 : 0));
1103 }
1104
1105 /* If we usually make new pseudos, do so here. This
1106 turns out to help machines that have conditional
1107 move insns. */
1108 /* ??? Conditional moves have already been handled.
1109 This may be obsolete. */
1110
1111 if (flag_expensive_optimizations)
1112 target = 0;
1113
1114 target = expand_binop (GET_MODE (var), ior_optab,
1115 tem1, tem2, target,
1116 1, OPTAB_WIDEN);
1117 }
1118 else if (normalizep != 1)
1119 {
1120 /* We know that either CVAL or UVAL is zero. If
1121 UVAL is zero, negate TARGET and `and' with CVAL.
1122 Otherwise, `and' with UVAL. */
1123 if (uval == const0_rtx)
1124 {
1125 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1126 target, NULL_RTX, 0);
1127 uval = cval;
1128 }
1129
1130 target = expand_and (uval, target,
1131 (GET_CODE (target) == REG
1132 && ! preserve_subexpressions_p ()
1133 ? target : NULL_RTX));
1134 }
1135
1136 emit_move_insn (var, target);
1137 seq = get_insns ();
1138 end_sequence ();
1139 #ifdef HAVE_cc0
1140 /* If INSN uses CC0, we must not separate it from the
1141 insn that sets cc0. */
1142 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1143 before = prev_nonnote_insn (before);
1144 #endif
1145 emit_insns_before (seq, before);
1146
1147 delete_insn (temp);
1148 next = NEXT_INSN (insn);
1149 delete_jump (insn);
1150
1151 if (after_regscan)
1152 {
1153 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1154 old_max_reg = max_reg_num ();
1155 }
1156
1157 changed = 1;
1158 continue;
1159 }
1160 else
1161 end_sequence ();
1162 }
1163 }
1164
1165 /* If branches are expensive, convert
1166 if (foo) bar++; to bar += (foo != 0);
1167 and similarly for "bar--;"
1168
1169 INSN is the conditional branch around the arithmetic. We set:
1170
1171 TEMP is the arithmetic insn.
1172 TEMP1 is the SET doing the arithmetic.
1173 TEMP2 is the operand being incremented or decremented.
1174 TEMP3 to the condition being tested.
1175 TEMP4 to the earliest insn used to find the condition. */
1176
1177 if ((BRANCH_COST >= 2
1178 #ifdef HAVE_incscc
1179 || HAVE_incscc
1180 #endif
1181 #ifdef HAVE_decscc
1182 || HAVE_decscc
1183 #endif
1184 )
1185 && ! reload_completed
1186 && this_is_condjump && ! this_is_simplejump
1187 && (temp = next_nonnote_insn (insn)) != 0
1188 && (temp1 = single_set (temp)) != 0
1189 && (temp2 = SET_DEST (temp1),
1190 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1191 && GET_CODE (SET_SRC (temp1)) == PLUS
1192 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1193 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1194 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1195 && ! side_effects_p (temp2)
1196 && ! may_trap_p (temp2)
1197 /* INSN must either branch to the insn after TEMP or the insn
1198 after TEMP must branch to the same place as INSN. */
1199 && (reallabelprev == temp
1200 || ((temp3 = next_active_insn (temp)) != 0
1201 && simplejump_p (temp3)
1202 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1203 && (temp3 = get_condition (insn, &temp4)) != 0
1204 /* We must be comparing objects whose modes imply the size.
1205 We could handle BLKmode if (1) emit_store_flag could
1206 and (2) we could find the size reliably. */
1207 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1208 && can_reverse_comparison_p (temp3, insn))
1209 {
1210 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1211 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1212
1213 start_sequence ();
1214
1215 /* It must be the case that TEMP2 is not modified in the range
1216 [TEMP4, INSN). The one exception we make is if the insn
1217 before INSN sets TEMP2 to something which is also unchanged
1218 in that range. In that case, we can move the initialization
1219 into our sequence. */
1220
1221 if ((temp5 = prev_active_insn (insn)) != 0
1222 && no_labels_between_p (temp5, insn)
1223 && GET_CODE (temp5) == INSN
1224 && (temp6 = single_set (temp5)) != 0
1225 && rtx_equal_p (temp2, SET_DEST (temp6))
1226 && (CONSTANT_P (SET_SRC (temp6))
1227 || GET_CODE (SET_SRC (temp6)) == REG
1228 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1229 {
1230 emit_insn (PATTERN (temp5));
1231 init_insn = temp5;
1232 init = SET_SRC (temp6);
1233 }
1234
1235 if (CONSTANT_P (init)
1236 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1237 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1238 XEXP (temp3, 0), XEXP (temp3, 1),
1239 VOIDmode,
1240 (code == LTU || code == LEU
1241 || code == GTU || code == GEU), 1);
1242
1243 /* If we can do the store-flag, do the addition or
1244 subtraction. */
1245
1246 if (target)
1247 target = expand_binop (GET_MODE (temp2),
1248 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1249 ? add_optab : sub_optab),
1250 temp2, target, temp2, 0, OPTAB_WIDEN);
1251
1252 if (target != 0)
1253 {
1254 /* Put the result back in temp2 in case it isn't already.
1255 Then replace the jump, possible a CC0-setting insn in
1256 front of the jump, and TEMP, with the sequence we have
1257 made. */
1258
1259 if (target != temp2)
1260 emit_move_insn (temp2, target);
1261
1262 seq = get_insns ();
1263 end_sequence ();
1264
1265 emit_insns_before (seq, temp4);
1266 delete_insn (temp);
1267
1268 if (init_insn)
1269 delete_insn (init_insn);
1270
1271 next = NEXT_INSN (insn);
1272 #ifdef HAVE_cc0
1273 delete_insn (prev_nonnote_insn (insn));
1274 #endif
1275 delete_insn (insn);
1276
1277 if (after_regscan)
1278 {
1279 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1280 old_max_reg = max_reg_num ();
1281 }
1282
1283 changed = 1;
1284 continue;
1285 }
1286 else
1287 end_sequence ();
1288 }
1289
1290 /* Simplify if (...) x = 1; else {...} if (x) ...
1291 We recognize this case scanning backwards as well.
1292
1293 TEMP is the assignment to x;
1294 TEMP1 is the label at the head of the second if. */
1295 /* ?? This should call get_condition to find the values being
1296 compared, instead of looking for a COMPARE insn when HAVE_cc0
1297 is not defined. This would allow it to work on the m88k. */
1298 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1299 is not defined and the condition is tested by a separate compare
1300 insn. This is because the code below assumes that the result
1301 of the compare dies in the following branch.
1302
1303 Not only that, but there might be other insns between the
1304 compare and branch whose results are live. Those insns need
1305 to be executed.
1306
1307 A way to fix this is to move the insns at JUMP_LABEL (insn)
1308 to before INSN. If we are running before flow, they will
1309 be deleted if they aren't needed. But this doesn't work
1310 well after flow.
1311
1312 This is really a special-case of jump threading, anyway. The
1313 right thing to do is to replace this and jump threading with
1314 much simpler code in cse.
1315
1316 This code has been turned off in the non-cc0 case in the
1317 meantime. */
1318
1319 #ifdef HAVE_cc0
1320 else if (this_is_simplejump
1321 /* Safe to skip USE and CLOBBER insns here
1322 since they will not be deleted. */
1323 && (temp = prev_active_insn (insn))
1324 && no_labels_between_p (temp, insn)
1325 && GET_CODE (temp) == INSN
1326 && GET_CODE (PATTERN (temp)) == SET
1327 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1328 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1329 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1330 /* If we find that the next value tested is `x'
1331 (TEMP1 is the insn where this happens), win. */
1332 && GET_CODE (temp1) == INSN
1333 && GET_CODE (PATTERN (temp1)) == SET
1334 #ifdef HAVE_cc0
1335 /* Does temp1 `tst' the value of x? */
1336 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1337 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1338 && (temp1 = next_nonnote_insn (temp1))
1339 #else
1340 /* Does temp1 compare the value of x against zero? */
1341 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1342 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1343 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1344 == SET_DEST (PATTERN (temp)))
1345 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1346 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1347 #endif
1348 && condjump_p (temp1))
1349 {
1350 /* Get the if_then_else from the condjump. */
1351 rtx choice = SET_SRC (PATTERN (temp1));
1352 if (GET_CODE (choice) == IF_THEN_ELSE)
1353 {
1354 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1355 rtx val = SET_SRC (PATTERN (temp));
1356 rtx cond
1357 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1358 val, const0_rtx);
1359 rtx ultimate;
1360
1361 if (cond == const_true_rtx)
1362 ultimate = XEXP (choice, 1);
1363 else if (cond == const0_rtx)
1364 ultimate = XEXP (choice, 2);
1365 else
1366 ultimate = 0;
1367
1368 if (ultimate == pc_rtx)
1369 ultimate = get_label_after (temp1);
1370 else if (ultimate && GET_CODE (ultimate) != RETURN)
1371 ultimate = XEXP (ultimate, 0);
1372
1373 if (ultimate && JUMP_LABEL(insn) != ultimate)
1374 changed |= redirect_jump (insn, ultimate);
1375 }
1376 }
1377 #endif
1378
1379 #if 0
1380 /* @@ This needs a bit of work before it will be right.
1381
1382 Any type of comparison can be accepted for the first and
1383 second compare. When rewriting the first jump, we must
1384 compute the what conditions can reach label3, and use the
1385 appropriate code. We can not simply reverse/swap the code
1386 of the first jump. In some cases, the second jump must be
1387 rewritten also.
1388
1389 For example,
1390 < == converts to > ==
1391 < != converts to == >
1392 etc.
1393
1394 If the code is written to only accept an '==' test for the second
1395 compare, then all that needs to be done is to swap the condition
1396 of the first branch.
1397
1398 It is questionable whether we want this optimization anyways,
1399 since if the user wrote code like this because he/she knew that
1400 the jump to label1 is taken most of the time, then rewriting
1401 this gives slower code. */
1402 /* @@ This should call get_condition to find the values being
1403 compared, instead of looking for a COMPARE insn when HAVE_cc0
1404 is not defined. This would allow it to work on the m88k. */
1405 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1406 is not defined and the condition is tested by a separate compare
1407 insn. This is because the code below assumes that the result
1408 of the compare dies in the following branch. */
1409
1410 /* Simplify test a ~= b
1411 condjump label1;
1412 test a == b
1413 condjump label2;
1414 jump label3;
1415 label1:
1416
1417 rewriting as
1418 test a ~~= b
1419 condjump label3
1420 test a == b
1421 condjump label2
1422 label1:
1423
1424 where ~= is an inequality, e.g. >, and ~~= is the swapped
1425 inequality, e.g. <.
1426
1427 We recognize this case scanning backwards.
1428
1429 TEMP is the conditional jump to `label2';
1430 TEMP1 is the test for `a == b';
1431 TEMP2 is the conditional jump to `label1';
1432 TEMP3 is the test for `a ~= b'. */
1433 else if (this_is_simplejump
1434 && (temp = prev_active_insn (insn))
1435 && no_labels_between_p (temp, insn)
1436 && condjump_p (temp)
1437 && (temp1 = prev_active_insn (temp))
1438 && no_labels_between_p (temp1, temp)
1439 && GET_CODE (temp1) == INSN
1440 && GET_CODE (PATTERN (temp1)) == SET
1441 #ifdef HAVE_cc0
1442 && sets_cc0_p (PATTERN (temp1)) == 1
1443 #else
1444 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1445 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1446 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1447 #endif
1448 && (temp2 = prev_active_insn (temp1))
1449 && no_labels_between_p (temp2, temp1)
1450 && condjump_p (temp2)
1451 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1452 && (temp3 = prev_active_insn (temp2))
1453 && no_labels_between_p (temp3, temp2)
1454 && GET_CODE (PATTERN (temp3)) == SET
1455 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1456 SET_DEST (PATTERN (temp1)))
1457 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1458 SET_SRC (PATTERN (temp3)))
1459 && ! inequality_comparisons_p (PATTERN (temp))
1460 && inequality_comparisons_p (PATTERN (temp2)))
1461 {
1462 rtx fallthrough_label = JUMP_LABEL (temp2);
1463
1464 ++LABEL_NUSES (fallthrough_label);
1465 if (swap_jump (temp2, JUMP_LABEL (insn)))
1466 {
1467 delete_insn (insn);
1468 changed = 1;
1469 }
1470
1471 if (--LABEL_NUSES (fallthrough_label) == 0)
1472 delete_insn (fallthrough_label);
1473 }
1474 #endif
1475 /* Simplify if (...) {... x = 1;} if (x) ...
1476
1477 We recognize this case backwards.
1478
1479 TEMP is the test of `x';
1480 TEMP1 is the assignment to `x' at the end of the
1481 previous statement. */
1482 /* @@ This should call get_condition to find the values being
1483 compared, instead of looking for a COMPARE insn when HAVE_cc0
1484 is not defined. This would allow it to work on the m88k. */
1485 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1486 is not defined and the condition is tested by a separate compare
1487 insn. This is because the code below assumes that the result
1488 of the compare dies in the following branch. */
1489
1490 /* ??? This has to be turned off. The problem is that the
1491 unconditional jump might indirectly end up branching to the
1492 label between TEMP1 and TEMP. We can't detect this, in general,
1493 since it may become a jump to there after further optimizations.
1494 If that jump is done, it will be deleted, so we will retry
1495 this optimization in the next pass, thus an infinite loop.
1496
1497 The present code prevents this by putting the jump after the
1498 label, but this is not logically correct. */
1499 #if 0
1500 else if (this_is_condjump
1501 /* Safe to skip USE and CLOBBER insns here
1502 since they will not be deleted. */
1503 && (temp = prev_active_insn (insn))
1504 && no_labels_between_p (temp, insn)
1505 && GET_CODE (temp) == INSN
1506 && GET_CODE (PATTERN (temp)) == SET
1507 #ifdef HAVE_cc0
1508 && sets_cc0_p (PATTERN (temp)) == 1
1509 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1510 #else
1511 /* Temp must be a compare insn, we can not accept a register
1512 to register move here, since it may not be simply a
1513 tst insn. */
1514 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1515 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1516 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1517 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1518 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1519 #endif
1520 /* May skip USE or CLOBBER insns here
1521 for checking for opportunity, since we
1522 take care of them later. */
1523 && (temp1 = prev_active_insn (temp))
1524 && GET_CODE (temp1) == INSN
1525 && GET_CODE (PATTERN (temp1)) == SET
1526 #ifdef HAVE_cc0
1527 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1528 #else
1529 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1530 == SET_DEST (PATTERN (temp1)))
1531 #endif
1532 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1533 /* If this isn't true, cse will do the job. */
1534 && ! no_labels_between_p (temp1, temp))
1535 {
1536 /* Get the if_then_else from the condjump. */
1537 rtx choice = SET_SRC (PATTERN (insn));
1538 if (GET_CODE (choice) == IF_THEN_ELSE
1539 && (GET_CODE (XEXP (choice, 0)) == EQ
1540 || GET_CODE (XEXP (choice, 0)) == NE))
1541 {
1542 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1543 rtx last_insn;
1544 rtx ultimate;
1545 rtx p;
1546
1547 /* Get the place that condjump will jump to
1548 if it is reached from here. */
1549 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1550 == want_nonzero)
1551 ultimate = XEXP (choice, 1);
1552 else
1553 ultimate = XEXP (choice, 2);
1554 /* Get it as a CODE_LABEL. */
1555 if (ultimate == pc_rtx)
1556 ultimate = get_label_after (insn);
1557 else
1558 /* Get the label out of the LABEL_REF. */
1559 ultimate = XEXP (ultimate, 0);
1560
1561 /* Insert the jump immediately before TEMP, specifically
1562 after the label that is between TEMP1 and TEMP. */
1563 last_insn = PREV_INSN (temp);
1564
1565 /* If we would be branching to the next insn, the jump
1566 would immediately be deleted and the re-inserted in
1567 a subsequent pass over the code. So don't do anything
1568 in that case. */
1569 if (next_active_insn (last_insn)
1570 != next_active_insn (ultimate))
1571 {
1572 emit_barrier_after (last_insn);
1573 p = emit_jump_insn_after (gen_jump (ultimate),
1574 last_insn);
1575 JUMP_LABEL (p) = ultimate;
1576 ++LABEL_NUSES (ultimate);
1577 if (INSN_UID (ultimate) < max_jump_chain
1578 && INSN_CODE (p) < max_jump_chain)
1579 {
1580 jump_chain[INSN_UID (p)]
1581 = jump_chain[INSN_UID (ultimate)];
1582 jump_chain[INSN_UID (ultimate)] = p;
1583 }
1584 changed = 1;
1585 continue;
1586 }
1587 }
1588 }
1589 #endif
1590 /* Detect a conditional jump going to the same place
1591 as an immediately following unconditional jump. */
1592 else if (this_is_condjump
1593 && (temp = next_active_insn (insn)) != 0
1594 && simplejump_p (temp)
1595 && (next_active_insn (JUMP_LABEL (insn))
1596 == next_active_insn (JUMP_LABEL (temp))))
1597 {
1598 rtx tem = temp;
1599
1600 /* ??? Optional. Disables some optimizations, but makes
1601 gcov output more accurate with -O. */
1602 if (flag_test_coverage && !reload_completed)
1603 for (tem = insn; tem != temp; tem = NEXT_INSN (tem))
1604 if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0)
1605 break;
1606
1607 if (tem == temp)
1608 {
1609 delete_jump (insn);
1610 changed = 1;
1611 continue;
1612 }
1613 }
1614 #ifdef HAVE_trap
1615 /* Detect a conditional jump jumping over an unconditional trap. */
1616 else if (HAVE_trap
1617 && this_is_condjump && ! this_is_simplejump
1618 && reallabelprev != 0
1619 && GET_CODE (reallabelprev) == INSN
1620 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
1621 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
1622 && prev_active_insn (reallabelprev) == insn
1623 && no_labels_between_p (insn, reallabelprev)
1624 && (temp2 = get_condition (insn, &temp4))
1625 && can_reverse_comparison_p (temp2, insn))
1626 {
1627 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
1628 XEXP (temp2, 0), XEXP (temp2, 1),
1629 TRAP_CODE (PATTERN (reallabelprev)));
1630
1631 if (new)
1632 {
1633 emit_insn_before (new, temp4);
1634 delete_insn (reallabelprev);
1635 delete_jump (insn);
1636 changed = 1;
1637 continue;
1638 }
1639 }
1640 /* Detect a jump jumping to an unconditional trap. */
1641 else if (HAVE_trap && this_is_condjump
1642 && (temp = next_active_insn (JUMP_LABEL (insn)))
1643 && GET_CODE (temp) == INSN
1644 && GET_CODE (PATTERN (temp)) == TRAP_IF
1645 && (this_is_simplejump
1646 || (temp2 = get_condition (insn, &temp4))))
1647 {
1648 rtx tc = TRAP_CONDITION (PATTERN (temp));
1649
1650 if (tc == const_true_rtx
1651 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
1652 {
1653 rtx new;
1654 /* Replace an unconditional jump to a trap with a trap. */
1655 if (this_is_simplejump)
1656 {
1657 emit_barrier_after (emit_insn_before (gen_trap (), insn));
1658 delete_jump (insn);
1659 changed = 1;
1660 continue;
1661 }
1662 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
1663 XEXP (temp2, 1),
1664 TRAP_CODE (PATTERN (temp)));
1665 if (new)
1666 {
1667 emit_insn_before (new, temp4);
1668 delete_jump (insn);
1669 changed = 1;
1670 continue;
1671 }
1672 }
1673 /* If the trap condition and jump condition are mutually
1674 exclusive, redirect the jump to the following insn. */
1675 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
1676 && ! this_is_simplejump
1677 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
1678 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
1679 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
1680 && redirect_jump (insn, get_label_after (temp)))
1681 {
1682 changed = 1;
1683 continue;
1684 }
1685 }
1686 #endif
1687
1688 /* Detect a conditional jump jumping over an unconditional jump. */
1689
1690 else if ((this_is_condjump || this_is_condjump_in_parallel)
1691 && ! this_is_simplejump
1692 && reallabelprev != 0
1693 && GET_CODE (reallabelprev) == JUMP_INSN
1694 && prev_active_insn (reallabelprev) == insn
1695 && no_labels_between_p (insn, reallabelprev)
1696 && simplejump_p (reallabelprev))
1697 {
1698 /* When we invert the unconditional jump, we will be
1699 decrementing the usage count of its old label.
1700 Make sure that we don't delete it now because that
1701 might cause the following code to be deleted. */
1702 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1703 rtx prev_label = JUMP_LABEL (insn);
1704
1705 if (prev_label)
1706 ++LABEL_NUSES (prev_label);
1707
1708 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1709 {
1710 /* It is very likely that if there are USE insns before
1711 this jump, they hold REG_DEAD notes. These REG_DEAD
1712 notes are no longer valid due to this optimization,
1713 and will cause the life-analysis that following passes
1714 (notably delayed-branch scheduling) to think that
1715 these registers are dead when they are not.
1716
1717 To prevent this trouble, we just remove the USE insns
1718 from the insn chain. */
1719
1720 while (prev_uses && GET_CODE (prev_uses) == INSN
1721 && GET_CODE (PATTERN (prev_uses)) == USE)
1722 {
1723 rtx useless = prev_uses;
1724 prev_uses = prev_nonnote_insn (prev_uses);
1725 delete_insn (useless);
1726 }
1727
1728 delete_insn (reallabelprev);
1729 next = insn;
1730 changed = 1;
1731 }
1732
1733 /* We can now safely delete the label if it is unreferenced
1734 since the delete_insn above has deleted the BARRIER. */
1735 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1736 delete_insn (prev_label);
1737 continue;
1738 }
1739 else
1740 {
1741 /* Detect a jump to a jump. */
1742
1743 nlabel = follow_jumps (JUMP_LABEL (insn));
1744 if (nlabel != JUMP_LABEL (insn)
1745 && redirect_jump (insn, nlabel))
1746 {
1747 changed = 1;
1748 next = insn;
1749 }
1750
1751 /* Look for if (foo) bar; else break; */
1752 /* The insns look like this:
1753 insn = condjump label1;
1754 ...range1 (some insns)...
1755 jump label2;
1756 label1:
1757 ...range2 (some insns)...
1758 jump somewhere unconditionally
1759 label2: */
1760 {
1761 rtx label1 = next_label (insn);
1762 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1763 /* Don't do this optimization on the first round, so that
1764 jump-around-a-jump gets simplified before we ask here
1765 whether a jump is unconditional.
1766
1767 Also don't do it when we are called after reload since
1768 it will confuse reorg. */
1769 if (! first
1770 && (reload_completed ? ! flag_delayed_branch : 1)
1771 /* Make sure INSN is something we can invert. */
1772 && condjump_p (insn)
1773 && label1 != 0
1774 && JUMP_LABEL (insn) == label1
1775 && LABEL_NUSES (label1) == 1
1776 && GET_CODE (range1end) == JUMP_INSN
1777 && simplejump_p (range1end))
1778 {
1779 rtx label2 = next_label (label1);
1780 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1781 if (range1end != range2end
1782 && JUMP_LABEL (range1end) == label2
1783 && GET_CODE (range2end) == JUMP_INSN
1784 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1785 /* Invert the jump condition, so we
1786 still execute the same insns in each case. */
1787 && invert_jump (insn, label1))
1788 {
1789 rtx range1beg = next_active_insn (insn);
1790 rtx range2beg = next_active_insn (label1);
1791 rtx range1after, range2after;
1792 rtx range1before, range2before;
1793 rtx rangenext;
1794
1795 /* Include in each range any notes before it, to be
1796 sure that we get the line number note if any, even
1797 if there are other notes here. */
1798 while (PREV_INSN (range1beg)
1799 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1800 range1beg = PREV_INSN (range1beg);
1801
1802 while (PREV_INSN (range2beg)
1803 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1804 range2beg = PREV_INSN (range2beg);
1805
1806 /* Don't move NOTEs for blocks or loops; shift them
1807 outside the ranges, where they'll stay put. */
1808 range1beg = squeeze_notes (range1beg, range1end);
1809 range2beg = squeeze_notes (range2beg, range2end);
1810
1811 /* Get current surrounds of the 2 ranges. */
1812 range1before = PREV_INSN (range1beg);
1813 range2before = PREV_INSN (range2beg);
1814 range1after = NEXT_INSN (range1end);
1815 range2after = NEXT_INSN (range2end);
1816
1817 /* Splice range2 where range1 was. */
1818 NEXT_INSN (range1before) = range2beg;
1819 PREV_INSN (range2beg) = range1before;
1820 NEXT_INSN (range2end) = range1after;
1821 PREV_INSN (range1after) = range2end;
1822 /* Splice range1 where range2 was. */
1823 NEXT_INSN (range2before) = range1beg;
1824 PREV_INSN (range1beg) = range2before;
1825 NEXT_INSN (range1end) = range2after;
1826 PREV_INSN (range2after) = range1end;
1827
1828 /* Check for a loop end note between the end of
1829 range2, and the next code label. If there is one,
1830 then what we have really seen is
1831 if (foo) break; end_of_loop;
1832 and moved the break sequence outside the loop.
1833 We must move the LOOP_END note to where the
1834 loop really ends now, or we will confuse loop
1835 optimization. Stop if we find a LOOP_BEG note
1836 first, since we don't want to move the LOOP_END
1837 note in that case. */
1838 for (;range2after != label2; range2after = rangenext)
1839 {
1840 rangenext = NEXT_INSN (range2after);
1841 if (GET_CODE (range2after) == NOTE)
1842 {
1843 if (NOTE_LINE_NUMBER (range2after)
1844 == NOTE_INSN_LOOP_END)
1845 {
1846 NEXT_INSN (PREV_INSN (range2after))
1847 = rangenext;
1848 PREV_INSN (rangenext)
1849 = PREV_INSN (range2after);
1850 PREV_INSN (range2after)
1851 = PREV_INSN (range1beg);
1852 NEXT_INSN (range2after) = range1beg;
1853 NEXT_INSN (PREV_INSN (range1beg))
1854 = range2after;
1855 PREV_INSN (range1beg) = range2after;
1856 }
1857 else if (NOTE_LINE_NUMBER (range2after)
1858 == NOTE_INSN_LOOP_BEG)
1859 break;
1860 }
1861 }
1862 changed = 1;
1863 continue;
1864 }
1865 }
1866 }
1867
1868 /* Now that the jump has been tensioned,
1869 try cross jumping: check for identical code
1870 before the jump and before its target label. */
1871
1872 /* First, cross jumping of conditional jumps: */
1873
1874 if (cross_jump && condjump_p (insn))
1875 {
1876 rtx newjpos, newlpos;
1877 rtx x = prev_real_insn (JUMP_LABEL (insn));
1878
1879 /* A conditional jump may be crossjumped
1880 only if the place it jumps to follows
1881 an opposing jump that comes back here. */
1882
1883 if (x != 0 && ! jump_back_p (x, insn))
1884 /* We have no opposing jump;
1885 cannot cross jump this insn. */
1886 x = 0;
1887
1888 newjpos = 0;
1889 /* TARGET is nonzero if it is ok to cross jump
1890 to code before TARGET. If so, see if matches. */
1891 if (x != 0)
1892 find_cross_jump (insn, x, 2,
1893 &newjpos, &newlpos);
1894
1895 if (newjpos != 0)
1896 {
1897 do_cross_jump (insn, newjpos, newlpos);
1898 /* Make the old conditional jump
1899 into an unconditional one. */
1900 SET_SRC (PATTERN (insn))
1901 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
1902 INSN_CODE (insn) = -1;
1903 emit_barrier_after (insn);
1904 /* Add to jump_chain unless this is a new label
1905 whose UID is too large. */
1906 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1907 {
1908 jump_chain[INSN_UID (insn)]
1909 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1910 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1911 }
1912 changed = 1;
1913 next = insn;
1914 }
1915 }
1916
1917 /* Cross jumping of unconditional jumps:
1918 a few differences. */
1919
1920 if (cross_jump && simplejump_p (insn))
1921 {
1922 rtx newjpos, newlpos;
1923 rtx target;
1924
1925 newjpos = 0;
1926
1927 /* TARGET is nonzero if it is ok to cross jump
1928 to code before TARGET. If so, see if matches. */
1929 find_cross_jump (insn, JUMP_LABEL (insn), 1,
1930 &newjpos, &newlpos);
1931
1932 /* If cannot cross jump to code before the label,
1933 see if we can cross jump to another jump to
1934 the same label. */
1935 /* Try each other jump to this label. */
1936 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
1937 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1938 target != 0 && newjpos == 0;
1939 target = jump_chain[INSN_UID (target)])
1940 if (target != insn
1941 && JUMP_LABEL (target) == JUMP_LABEL (insn)
1942 /* Ignore TARGET if it's deleted. */
1943 && ! INSN_DELETED_P (target))
1944 find_cross_jump (insn, target, 2,
1945 &newjpos, &newlpos);
1946
1947 if (newjpos != 0)
1948 {
1949 do_cross_jump (insn, newjpos, newlpos);
1950 changed = 1;
1951 next = insn;
1952 }
1953 }
1954
1955 /* This code was dead in the previous jump.c! */
1956 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
1957 {
1958 /* Return insns all "jump to the same place"
1959 so we can cross-jump between any two of them. */
1960
1961 rtx newjpos, newlpos, target;
1962
1963 newjpos = 0;
1964
1965 /* If cannot cross jump to code before the label,
1966 see if we can cross jump to another jump to
1967 the same label. */
1968 /* Try each other jump to this label. */
1969 for (target = jump_chain[0];
1970 target != 0 && newjpos == 0;
1971 target = jump_chain[INSN_UID (target)])
1972 if (target != insn
1973 && ! INSN_DELETED_P (target)
1974 && GET_CODE (PATTERN (target)) == RETURN)
1975 find_cross_jump (insn, target, 2,
1976 &newjpos, &newlpos);
1977
1978 if (newjpos != 0)
1979 {
1980 do_cross_jump (insn, newjpos, newlpos);
1981 changed = 1;
1982 next = insn;
1983 }
1984 }
1985 }
1986 }
1987
1988 first = 0;
1989 }
1990
1991 /* Delete extraneous line number notes.
1992 Note that two consecutive notes for different lines are not really
1993 extraneous. There should be some indication where that line belonged,
1994 even if it became empty. */
1995
1996 {
1997 rtx last_note = 0;
1998
1999 for (insn = f; insn; insn = NEXT_INSN (insn))
2000 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2001 {
2002 /* Delete this note if it is identical to previous note. */
2003 if (last_note
2004 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2005 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2006 {
2007 delete_insn (insn);
2008 continue;
2009 }
2010
2011 last_note = insn;
2012 }
2013 }
2014
2015 #ifdef HAVE_return
2016 if (HAVE_return)
2017 {
2018 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2019 in front of it. If the machine allows it at this point (we might be
2020 after reload for a leaf routine), it will improve optimization for it
2021 to be there. We do this both here and at the start of this pass since
2022 the RETURN might have been deleted by some of our optimizations. */
2023 insn = get_last_insn ();
2024 while (insn && GET_CODE (insn) == NOTE)
2025 insn = PREV_INSN (insn);
2026
2027 if (insn && GET_CODE (insn) != BARRIER)
2028 {
2029 emit_jump_insn (gen_return ());
2030 emit_barrier ();
2031 }
2032 }
2033 #endif
2034
2035 can_reach_end = calculate_can_reach_end (last_insn, 0, 1);
2036
2037 /* Show JUMP_CHAIN no longer valid. */
2038 jump_chain = 0;
2039 }
2040 \f
2041 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2042 notes whose labels don't occur in the insn any more. Returns the
2043 largest INSN_UID found. */
2044 static int
2045 init_label_info (f)
2046 rtx f;
2047 {
2048 int largest_uid = 0;
2049 rtx insn;
2050
2051 for (insn = f; insn; insn = NEXT_INSN (insn))
2052 {
2053 if (GET_CODE (insn) == CODE_LABEL)
2054 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
2055 else if (GET_CODE (insn) == JUMP_INSN)
2056 JUMP_LABEL (insn) = 0;
2057 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2058 {
2059 rtx note, next;
2060
2061 for (note = REG_NOTES (insn); note; note = next)
2062 {
2063 next = XEXP (note, 1);
2064 if (REG_NOTE_KIND (note) == REG_LABEL
2065 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
2066 remove_note (insn, note);
2067 }
2068 }
2069 if (INSN_UID (insn) > largest_uid)
2070 largest_uid = INSN_UID (insn);
2071 }
2072
2073 return largest_uid;
2074 }
2075
2076 /* Delete insns following barriers, up to next label. */
2077 static void
2078 delete_barrier_successors (f)
2079 rtx f;
2080 {
2081 rtx insn;
2082
2083 for (insn = f; insn;)
2084 {
2085 if (GET_CODE (insn) == BARRIER)
2086 {
2087 insn = NEXT_INSN (insn);
2088 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
2089 {
2090 if (GET_CODE (insn) == NOTE
2091 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2092 insn = NEXT_INSN (insn);
2093 else
2094 insn = delete_insn (insn);
2095 }
2096 /* INSN is now the code_label. */
2097 }
2098 else
2099 insn = NEXT_INSN (insn);
2100 }
2101 }
2102
2103 /* Mark the label each jump jumps to.
2104 Combine consecutive labels, and count uses of labels.
2105
2106 For each label, make a chain (using `jump_chain')
2107 of all the *unconditional* jumps that jump to it;
2108 also make a chain of all returns.
2109
2110 CROSS_JUMP indicates whether we are doing cross jumping
2111 and if we are whether we will be paying attention to
2112 death notes or not. */
2113
2114 static void
2115 mark_all_labels (f, cross_jump)
2116 rtx f;
2117 int cross_jump;
2118 {
2119 rtx insn;
2120
2121 for (insn = f; insn; insn = NEXT_INSN (insn))
2122 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2123 {
2124 mark_jump_label (PATTERN (insn), insn, cross_jump);
2125 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
2126 {
2127 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2128 {
2129 jump_chain[INSN_UID (insn)]
2130 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2131 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2132 }
2133 if (GET_CODE (PATTERN (insn)) == RETURN)
2134 {
2135 jump_chain[INSN_UID (insn)] = jump_chain[0];
2136 jump_chain[0] = insn;
2137 }
2138 }
2139 }
2140 }
2141
2142 /* Delete all labels already not referenced.
2143 Also find and return the last insn. */
2144
2145 static rtx
2146 delete_unreferenced_labels (f)
2147 rtx f;
2148 {
2149 rtx final = NULL_RTX;
2150 rtx insn;
2151
2152 for (insn = f; insn; )
2153 {
2154 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
2155 insn = delete_insn (insn);
2156 else
2157 {
2158 final = insn;
2159 insn = NEXT_INSN (insn);
2160 }
2161 }
2162
2163 return final;
2164 }
2165
2166 /* Delete various simple forms of moves which have no necessary
2167 side effect. */
2168
2169 static void
2170 delete_noop_moves (f)
2171 rtx f;
2172 {
2173 rtx insn, next;
2174
2175 for (insn = f; insn; )
2176 {
2177 next = NEXT_INSN (insn);
2178
2179 if (GET_CODE (insn) == INSN)
2180 {
2181 register rtx body = PATTERN (insn);
2182
2183 /* Combine stack_adjusts with following push_insns. */
2184 #ifdef PUSH_ROUNDING
2185 if (GET_CODE (body) == SET
2186 && SET_DEST (body) == stack_pointer_rtx
2187 && GET_CODE (SET_SRC (body)) == PLUS
2188 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
2189 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
2190 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
2191 {
2192 rtx p;
2193 rtx stack_adjust_insn = insn;
2194 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
2195 int total_pushed = 0;
2196 int pushes = 0;
2197
2198 /* Find all successive push insns. */
2199 p = insn;
2200 /* Don't convert more than three pushes;
2201 that starts adding too many displaced addresses
2202 and the whole thing starts becoming a losing
2203 proposition. */
2204 while (pushes < 3)
2205 {
2206 rtx pbody, dest;
2207 p = next_nonnote_insn (p);
2208 if (p == 0 || GET_CODE (p) != INSN)
2209 break;
2210 pbody = PATTERN (p);
2211 if (GET_CODE (pbody) != SET)
2212 break;
2213 dest = SET_DEST (pbody);
2214 /* Allow a no-op move between the adjust and the push. */
2215 if (GET_CODE (dest) == REG
2216 && GET_CODE (SET_SRC (pbody)) == REG
2217 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2218 continue;
2219 if (! (GET_CODE (dest) == MEM
2220 && GET_CODE (XEXP (dest, 0)) == POST_INC
2221 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2222 break;
2223 pushes++;
2224 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
2225 > stack_adjust_amount)
2226 break;
2227 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2228 }
2229
2230 /* Discard the amount pushed from the stack adjust;
2231 maybe eliminate it entirely. */
2232 if (total_pushed >= stack_adjust_amount)
2233 {
2234 delete_computation (stack_adjust_insn);
2235 total_pushed = stack_adjust_amount;
2236 }
2237 else
2238 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
2239 = GEN_INT (stack_adjust_amount - total_pushed);
2240
2241 /* Change the appropriate push insns to ordinary stores. */
2242 p = insn;
2243 while (total_pushed > 0)
2244 {
2245 rtx pbody, dest;
2246 p = next_nonnote_insn (p);
2247 if (GET_CODE (p) != INSN)
2248 break;
2249 pbody = PATTERN (p);
2250 if (GET_CODE (pbody) != SET)
2251 break;
2252 dest = SET_DEST (pbody);
2253 /* Allow a no-op move between the adjust and the push. */
2254 if (GET_CODE (dest) == REG
2255 && GET_CODE (SET_SRC (pbody)) == REG
2256 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2257 continue;
2258 if (! (GET_CODE (dest) == MEM
2259 && GET_CODE (XEXP (dest, 0)) == POST_INC
2260 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2261 break;
2262 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2263 /* If this push doesn't fully fit in the space
2264 of the stack adjust that we deleted,
2265 make another stack adjust here for what we
2266 didn't use up. There should be peepholes
2267 to recognize the resulting sequence of insns. */
2268 if (total_pushed < 0)
2269 {
2270 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
2271 GEN_INT (- total_pushed)),
2272 p);
2273 break;
2274 }
2275 XEXP (dest, 0)
2276 = plus_constant (stack_pointer_rtx, total_pushed);
2277 }
2278 }
2279 #endif
2280
2281 /* Detect and delete no-op move instructions
2282 resulting from not allocating a parameter in a register. */
2283
2284 if (GET_CODE (body) == SET
2285 && (SET_DEST (body) == SET_SRC (body)
2286 || (GET_CODE (SET_DEST (body)) == MEM
2287 && GET_CODE (SET_SRC (body)) == MEM
2288 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
2289 && ! (GET_CODE (SET_DEST (body)) == MEM
2290 && MEM_VOLATILE_P (SET_DEST (body)))
2291 && ! (GET_CODE (SET_SRC (body)) == MEM
2292 && MEM_VOLATILE_P (SET_SRC (body))))
2293 delete_computation (insn);
2294
2295 /* Detect and ignore no-op move instructions
2296 resulting from smart or fortuitous register allocation. */
2297
2298 else if (GET_CODE (body) == SET)
2299 {
2300 int sreg = true_regnum (SET_SRC (body));
2301 int dreg = true_regnum (SET_DEST (body));
2302
2303 if (sreg == dreg && sreg >= 0)
2304 delete_insn (insn);
2305 else if (sreg >= 0 && dreg >= 0)
2306 {
2307 rtx trial;
2308 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
2309 sreg, NULL_PTR, dreg,
2310 GET_MODE (SET_SRC (body)));
2311
2312 if (tem != 0
2313 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
2314 {
2315 /* DREG may have been the target of a REG_DEAD note in
2316 the insn which makes INSN redundant. If so, reorg
2317 would still think it is dead. So search for such a
2318 note and delete it if we find it. */
2319 if (! find_regno_note (insn, REG_UNUSED, dreg))
2320 for (trial = prev_nonnote_insn (insn);
2321 trial && GET_CODE (trial) != CODE_LABEL;
2322 trial = prev_nonnote_insn (trial))
2323 if (find_regno_note (trial, REG_DEAD, dreg))
2324 {
2325 remove_death (dreg, trial);
2326 break;
2327 }
2328
2329 /* Deleting insn could lose a death-note for SREG. */
2330 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
2331 {
2332 /* Change this into a USE so that we won't emit
2333 code for it, but still can keep the note. */
2334 PATTERN (insn)
2335 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
2336 INSN_CODE (insn) = -1;
2337 /* Remove all reg notes but the REG_DEAD one. */
2338 REG_NOTES (insn) = trial;
2339 XEXP (trial, 1) = NULL_RTX;
2340 }
2341 else
2342 delete_insn (insn);
2343 }
2344 }
2345 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
2346 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
2347 NULL_PTR, 0,
2348 GET_MODE (SET_DEST (body))))
2349 {
2350 /* This handles the case where we have two consecutive
2351 assignments of the same constant to pseudos that didn't
2352 get a hard reg. Each SET from the constant will be
2353 converted into a SET of the spill register and an
2354 output reload will be made following it. This produces
2355 two loads of the same constant into the same spill
2356 register. */
2357
2358 rtx in_insn = insn;
2359
2360 /* Look back for a death note for the first reg.
2361 If there is one, it is no longer accurate. */
2362 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
2363 {
2364 if ((GET_CODE (in_insn) == INSN
2365 || GET_CODE (in_insn) == JUMP_INSN)
2366 && find_regno_note (in_insn, REG_DEAD, dreg))
2367 {
2368 remove_death (dreg, in_insn);
2369 break;
2370 }
2371 in_insn = PREV_INSN (in_insn);
2372 }
2373
2374 /* Delete the second load of the value. */
2375 delete_insn (insn);
2376 }
2377 }
2378 else if (GET_CODE (body) == PARALLEL)
2379 {
2380 /* If each part is a set between two identical registers or
2381 a USE or CLOBBER, delete the insn. */
2382 int i, sreg, dreg;
2383 rtx tem;
2384
2385 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
2386 {
2387 tem = XVECEXP (body, 0, i);
2388 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
2389 continue;
2390
2391 if (GET_CODE (tem) != SET
2392 || (sreg = true_regnum (SET_SRC (tem))) < 0
2393 || (dreg = true_regnum (SET_DEST (tem))) < 0
2394 || dreg != sreg)
2395 break;
2396 }
2397
2398 if (i < 0)
2399 delete_insn (insn);
2400 }
2401 /* Also delete insns to store bit fields if they are no-ops. */
2402 /* Not worth the hair to detect this in the big-endian case. */
2403 else if (! BYTES_BIG_ENDIAN
2404 && GET_CODE (body) == SET
2405 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
2406 && XEXP (SET_DEST (body), 2) == const0_rtx
2407 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
2408 && ! (GET_CODE (SET_SRC (body)) == MEM
2409 && MEM_VOLATILE_P (SET_SRC (body))))
2410 delete_insn (insn);
2411 }
2412 insn = next;
2413 }
2414 }
2415
2416 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2417 If so indicate that this function can drop off the end by returning
2418 1, else return 0.
2419
2420 CHECK_DELETED indicates whether we must check if the note being
2421 searched for has the deleted flag set.
2422
2423 DELETE_FINAL_NOTE indicates whether we should delete the note
2424 if we find it. */
2425
2426 static int
2427 calculate_can_reach_end (last, check_deleted, delete_final_note)
2428 rtx last;
2429 int check_deleted;
2430 int delete_final_note;
2431 {
2432 rtx insn = last;
2433 int n_labels = 1;
2434
2435 while (insn != NULL_RTX)
2436 {
2437 int ok = 0;
2438
2439 /* One label can follow the end-note: the return label. */
2440 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2441 ok = 1;
2442 /* Ordinary insns can follow it if returning a structure. */
2443 else if (GET_CODE (insn) == INSN)
2444 ok = 1;
2445 /* If machine uses explicit RETURN insns, no epilogue,
2446 then one of them follows the note. */
2447 else if (GET_CODE (insn) == JUMP_INSN
2448 && GET_CODE (PATTERN (insn)) == RETURN)
2449 ok = 1;
2450 /* A barrier can follow the return insn. */
2451 else if (GET_CODE (insn) == BARRIER)
2452 ok = 1;
2453 /* Other kinds of notes can follow also. */
2454 else if (GET_CODE (insn) == NOTE
2455 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2456 ok = 1;
2457
2458 if (ok != 1)
2459 break;
2460
2461 insn = PREV_INSN (insn);
2462 }
2463
2464 /* See if we backed up to the appropriate type of note. */
2465 if (insn != NULL_RTX
2466 && GET_CODE (insn) == NOTE
2467 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
2468 && (check_deleted == 0
2469 || ! INSN_DELETED_P (insn)))
2470 {
2471 if (delete_final_note)
2472 delete_insn (insn);
2473 return 1;
2474 }
2475
2476 return 0;
2477 }
2478
2479 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2480 jump. Assume that this unconditional jump is to the exit test code. If
2481 the code is sufficiently simple, make a copy of it before INSN,
2482 followed by a jump to the exit of the loop. Then delete the unconditional
2483 jump after INSN.
2484
2485 Return 1 if we made the change, else 0.
2486
2487 This is only safe immediately after a regscan pass because it uses the
2488 values of regno_first_uid and regno_last_uid. */
2489
2490 static int
2491 duplicate_loop_exit_test (loop_start)
2492 rtx loop_start;
2493 {
2494 rtx insn, set, reg, p, link;
2495 rtx copy = 0;
2496 int num_insns = 0;
2497 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2498 rtx lastexit;
2499 int max_reg = max_reg_num ();
2500 rtx *reg_map = 0;
2501
2502 /* Scan the exit code. We do not perform this optimization if any insn:
2503
2504 is a CALL_INSN
2505 is a CODE_LABEL
2506 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2507 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2508 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2509 is not valid.
2510
2511 We also do not do this if we find an insn with ASM_OPERANDS. While
2512 this restriction should not be necessary, copying an insn with
2513 ASM_OPERANDS can confuse asm_noperands in some cases.
2514
2515 Also, don't do this if the exit code is more than 20 insns. */
2516
2517 for (insn = exitcode;
2518 insn
2519 && ! (GET_CODE (insn) == NOTE
2520 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2521 insn = NEXT_INSN (insn))
2522 {
2523 switch (GET_CODE (insn))
2524 {
2525 case CODE_LABEL:
2526 case CALL_INSN:
2527 return 0;
2528 case NOTE:
2529 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2530 a jump immediately after the loop start that branches outside
2531 the loop but within an outer loop, near the exit test.
2532 If we copied this exit test and created a phony
2533 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2534 before the exit test look like these could be safely moved
2535 out of the loop even if they actually may be never executed.
2536 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2537
2538 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2539 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2540 return 0;
2541
2542 if (optimize < 2
2543 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2544 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
2545 /* If we were to duplicate this code, we would not move
2546 the BLOCK notes, and so debugging the moved code would
2547 be difficult. Thus, we only move the code with -O2 or
2548 higher. */
2549 return 0;
2550
2551 break;
2552 case JUMP_INSN:
2553 case INSN:
2554 /* The code below would grossly mishandle REG_WAS_0 notes,
2555 so get rid of them here. */
2556 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
2557 remove_note (insn, p);
2558 if (++num_insns > 20
2559 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2560 || find_reg_note (insn, REG_LIBCALL, NULL_RTX)
2561 || asm_noperands (PATTERN (insn)) > 0)
2562 return 0;
2563 break;
2564 default:
2565 break;
2566 }
2567 }
2568
2569 /* Unless INSN is zero, we can do the optimization. */
2570 if (insn == 0)
2571 return 0;
2572
2573 lastexit = insn;
2574
2575 /* See if any insn sets a register only used in the loop exit code and
2576 not a user variable. If so, replace it with a new register. */
2577 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2578 if (GET_CODE (insn) == INSN
2579 && (set = single_set (insn)) != 0
2580 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2581 || (GET_CODE (reg) == SUBREG
2582 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2583 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2584 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2585 {
2586 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2587 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2588 break;
2589
2590 if (p != lastexit)
2591 {
2592 /* We can do the replacement. Allocate reg_map if this is the
2593 first replacement we found. */
2594 if (reg_map == 0)
2595 {
2596 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2597 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2598 }
2599
2600 REG_LOOP_TEST_P (reg) = 1;
2601
2602 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2603 }
2604 }
2605
2606 /* Now copy each insn. */
2607 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2608 switch (GET_CODE (insn))
2609 {
2610 case BARRIER:
2611 copy = emit_barrier_before (loop_start);
2612 break;
2613 case NOTE:
2614 /* Only copy line-number notes. */
2615 if (NOTE_LINE_NUMBER (insn) >= 0)
2616 {
2617 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2618 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2619 }
2620 break;
2621
2622 case INSN:
2623 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2624 if (reg_map)
2625 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2626
2627 mark_jump_label (PATTERN (copy), copy, 0);
2628
2629 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2630 make them. */
2631 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2632 if (REG_NOTE_KIND (link) != REG_LABEL)
2633 REG_NOTES (copy)
2634 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2635 XEXP (link, 0),
2636 REG_NOTES (copy)));
2637 if (reg_map && REG_NOTES (copy))
2638 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2639 break;
2640
2641 case JUMP_INSN:
2642 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2643 if (reg_map)
2644 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2645 mark_jump_label (PATTERN (copy), copy, 0);
2646 if (REG_NOTES (insn))
2647 {
2648 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2649 if (reg_map)
2650 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2651 }
2652
2653 /* If this is a simple jump, add it to the jump chain. */
2654
2655 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2656 && simplejump_p (copy))
2657 {
2658 jump_chain[INSN_UID (copy)]
2659 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2660 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2661 }
2662 break;
2663
2664 default:
2665 abort ();
2666 }
2667
2668 /* Now clean up by emitting a jump to the end label and deleting the jump
2669 at the start of the loop. */
2670 if (! copy || GET_CODE (copy) != BARRIER)
2671 {
2672 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2673 loop_start);
2674 mark_jump_label (PATTERN (copy), copy, 0);
2675 if (INSN_UID (copy) < max_jump_chain
2676 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2677 {
2678 jump_chain[INSN_UID (copy)]
2679 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2680 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2681 }
2682 emit_barrier_before (loop_start);
2683 }
2684
2685 /* Mark the exit code as the virtual top of the converted loop. */
2686 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2687
2688 delete_insn (next_nonnote_insn (loop_start));
2689
2690 return 1;
2691 }
2692 \f
2693 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2694 loop-end notes between START and END out before START. Assume that
2695 END is not such a note. START may be such a note. Returns the value
2696 of the new starting insn, which may be different if the original start
2697 was such a note. */
2698
2699 rtx
2700 squeeze_notes (start, end)
2701 rtx start, end;
2702 {
2703 rtx insn;
2704 rtx next;
2705
2706 for (insn = start; insn != end; insn = next)
2707 {
2708 next = NEXT_INSN (insn);
2709 if (GET_CODE (insn) == NOTE
2710 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2711 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2712 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2713 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2714 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2715 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2716 {
2717 if (insn == start)
2718 start = next;
2719 else
2720 {
2721 rtx prev = PREV_INSN (insn);
2722 PREV_INSN (insn) = PREV_INSN (start);
2723 NEXT_INSN (insn) = start;
2724 NEXT_INSN (PREV_INSN (insn)) = insn;
2725 PREV_INSN (NEXT_INSN (insn)) = insn;
2726 NEXT_INSN (prev) = next;
2727 PREV_INSN (next) = prev;
2728 }
2729 }
2730 }
2731
2732 return start;
2733 }
2734 \f
2735 /* Compare the instructions before insn E1 with those before E2
2736 to find an opportunity for cross jumping.
2737 (This means detecting identical sequences of insns followed by
2738 jumps to the same place, or followed by a label and a jump
2739 to that label, and replacing one with a jump to the other.)
2740
2741 Assume E1 is a jump that jumps to label E2
2742 (that is not always true but it might as well be).
2743 Find the longest possible equivalent sequences
2744 and store the first insns of those sequences into *F1 and *F2.
2745 Store zero there if no equivalent preceding instructions are found.
2746
2747 We give up if we find a label in stream 1.
2748 Actually we could transfer that label into stream 2. */
2749
2750 static void
2751 find_cross_jump (e1, e2, minimum, f1, f2)
2752 rtx e1, e2;
2753 int minimum;
2754 rtx *f1, *f2;
2755 {
2756 register rtx i1 = e1, i2 = e2;
2757 register rtx p1, p2;
2758 int lose = 0;
2759
2760 rtx last1 = 0, last2 = 0;
2761 rtx afterlast1 = 0, afterlast2 = 0;
2762
2763 *f1 = 0;
2764 *f2 = 0;
2765
2766 while (1)
2767 {
2768 i1 = prev_nonnote_insn (i1);
2769
2770 i2 = PREV_INSN (i2);
2771 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2772 i2 = PREV_INSN (i2);
2773
2774 if (i1 == 0)
2775 break;
2776
2777 /* Don't allow the range of insns preceding E1 or E2
2778 to include the other (E2 or E1). */
2779 if (i2 == e1 || i1 == e2)
2780 break;
2781
2782 /* If we will get to this code by jumping, those jumps will be
2783 tensioned to go directly to the new label (before I2),
2784 so this cross-jumping won't cost extra. So reduce the minimum. */
2785 if (GET_CODE (i1) == CODE_LABEL)
2786 {
2787 --minimum;
2788 break;
2789 }
2790
2791 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2792 break;
2793
2794 /* Avoid moving insns across EH regions if either of the insns
2795 can throw. */
2796 if (flag_exceptions
2797 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
2798 && !in_same_eh_region (i1, i2))
2799 break;
2800
2801 p1 = PATTERN (i1);
2802 p2 = PATTERN (i2);
2803
2804 /* If this is a CALL_INSN, compare register usage information.
2805 If we don't check this on stack register machines, the two
2806 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2807 numbers of stack registers in the same basic block.
2808 If we don't check this on machines with delay slots, a delay slot may
2809 be filled that clobbers a parameter expected by the subroutine.
2810
2811 ??? We take the simple route for now and assume that if they're
2812 equal, they were constructed identically. */
2813
2814 if (GET_CODE (i1) == CALL_INSN
2815 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2816 CALL_INSN_FUNCTION_USAGE (i2)))
2817 lose = 1;
2818
2819 #ifdef STACK_REGS
2820 /* If cross_jump_death_matters is not 0, the insn's mode
2821 indicates whether or not the insn contains any stack-like
2822 regs. */
2823
2824 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2825 {
2826 /* If register stack conversion has already been done, then
2827 death notes must also be compared before it is certain that
2828 the two instruction streams match. */
2829
2830 rtx note;
2831 HARD_REG_SET i1_regset, i2_regset;
2832
2833 CLEAR_HARD_REG_SET (i1_regset);
2834 CLEAR_HARD_REG_SET (i2_regset);
2835
2836 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2837 if (REG_NOTE_KIND (note) == REG_DEAD
2838 && STACK_REG_P (XEXP (note, 0)))
2839 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2840
2841 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2842 if (REG_NOTE_KIND (note) == REG_DEAD
2843 && STACK_REG_P (XEXP (note, 0)))
2844 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2845
2846 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2847
2848 lose = 1;
2849
2850 done:
2851 ;
2852 }
2853 #endif
2854
2855 /* Don't allow old-style asm or volatile extended asms to be accepted
2856 for cross jumping purposes. It is conceptually correct to allow
2857 them, since cross-jumping preserves the dynamic instruction order
2858 even though it is changing the static instruction order. However,
2859 if an asm is being used to emit an assembler pseudo-op, such as
2860 the MIPS `.set reorder' pseudo-op, then the static instruction order
2861 matters and it must be preserved. */
2862 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
2863 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
2864 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
2865 lose = 1;
2866
2867 if (lose || GET_CODE (p1) != GET_CODE (p2)
2868 || ! rtx_renumbered_equal_p (p1, p2))
2869 {
2870 /* The following code helps take care of G++ cleanups. */
2871 rtx equiv1;
2872 rtx equiv2;
2873
2874 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2875 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2876 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2877 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2878 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2879 /* If the equivalences are not to a constant, they may
2880 reference pseudos that no longer exist, so we can't
2881 use them. */
2882 && CONSTANT_P (XEXP (equiv1, 0))
2883 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2884 {
2885 rtx s1 = single_set (i1);
2886 rtx s2 = single_set (i2);
2887 if (s1 != 0 && s2 != 0
2888 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2889 {
2890 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2891 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2892 if (! rtx_renumbered_equal_p (p1, p2))
2893 cancel_changes (0);
2894 else if (apply_change_group ())
2895 goto win;
2896 }
2897 }
2898
2899 /* Insns fail to match; cross jumping is limited to the following
2900 insns. */
2901
2902 #ifdef HAVE_cc0
2903 /* Don't allow the insn after a compare to be shared by
2904 cross-jumping unless the compare is also shared.
2905 Here, if either of these non-matching insns is a compare,
2906 exclude the following insn from possible cross-jumping. */
2907 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2908 last1 = afterlast1, last2 = afterlast2, ++minimum;
2909 #endif
2910
2911 /* If cross-jumping here will feed a jump-around-jump
2912 optimization, this jump won't cost extra, so reduce
2913 the minimum. */
2914 if (GET_CODE (i1) == JUMP_INSN
2915 && JUMP_LABEL (i1)
2916 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2917 --minimum;
2918 break;
2919 }
2920
2921 win:
2922 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2923 {
2924 /* Ok, this insn is potentially includable in a cross-jump here. */
2925 afterlast1 = last1, afterlast2 = last2;
2926 last1 = i1, last2 = i2, --minimum;
2927 }
2928 }
2929
2930 if (minimum <= 0 && last1 != 0 && last1 != e1)
2931 *f1 = last1, *f2 = last2;
2932 }
2933
2934 static void
2935 do_cross_jump (insn, newjpos, newlpos)
2936 rtx insn, newjpos, newlpos;
2937 {
2938 /* Find an existing label at this point
2939 or make a new one if there is none. */
2940 register rtx label = get_label_before (newlpos);
2941
2942 /* Make the same jump insn jump to the new point. */
2943 if (GET_CODE (PATTERN (insn)) == RETURN)
2944 {
2945 /* Remove from jump chain of returns. */
2946 delete_from_jump_chain (insn);
2947 /* Change the insn. */
2948 PATTERN (insn) = gen_jump (label);
2949 INSN_CODE (insn) = -1;
2950 JUMP_LABEL (insn) = label;
2951 LABEL_NUSES (label)++;
2952 /* Add to new the jump chain. */
2953 if (INSN_UID (label) < max_jump_chain
2954 && INSN_UID (insn) < max_jump_chain)
2955 {
2956 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2957 jump_chain[INSN_UID (label)] = insn;
2958 }
2959 }
2960 else
2961 redirect_jump (insn, label);
2962
2963 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2964 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2965 the NEWJPOS stream. */
2966
2967 while (newjpos != insn)
2968 {
2969 rtx lnote;
2970
2971 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2972 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2973 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2974 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2975 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2976 remove_note (newlpos, lnote);
2977
2978 delete_insn (newjpos);
2979 newjpos = next_real_insn (newjpos);
2980 newlpos = next_real_insn (newlpos);
2981 }
2982 }
2983 \f
2984 /* Return the label before INSN, or put a new label there. */
2985
2986 rtx
2987 get_label_before (insn)
2988 rtx insn;
2989 {
2990 rtx label;
2991
2992 /* Find an existing label at this point
2993 or make a new one if there is none. */
2994 label = prev_nonnote_insn (insn);
2995
2996 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2997 {
2998 rtx prev = PREV_INSN (insn);
2999
3000 label = gen_label_rtx ();
3001 emit_label_after (label, prev);
3002 LABEL_NUSES (label) = 0;
3003 }
3004 return label;
3005 }
3006
3007 /* Return the label after INSN, or put a new label there. */
3008
3009 rtx
3010 get_label_after (insn)
3011 rtx insn;
3012 {
3013 rtx label;
3014
3015 /* Find an existing label at this point
3016 or make a new one if there is none. */
3017 label = next_nonnote_insn (insn);
3018
3019 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3020 {
3021 label = gen_label_rtx ();
3022 emit_label_after (label, insn);
3023 LABEL_NUSES (label) = 0;
3024 }
3025 return label;
3026 }
3027 \f
3028 /* Return 1 if INSN is a jump that jumps to right after TARGET
3029 only on the condition that TARGET itself would drop through.
3030 Assumes that TARGET is a conditional jump. */
3031
3032 static int
3033 jump_back_p (insn, target)
3034 rtx insn, target;
3035 {
3036 rtx cinsn, ctarget;
3037 enum rtx_code codei, codet;
3038
3039 if (simplejump_p (insn) || ! condjump_p (insn)
3040 || simplejump_p (target)
3041 || target != prev_real_insn (JUMP_LABEL (insn)))
3042 return 0;
3043
3044 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
3045 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
3046
3047 codei = GET_CODE (cinsn);
3048 codet = GET_CODE (ctarget);
3049
3050 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
3051 {
3052 if (! can_reverse_comparison_p (cinsn, insn))
3053 return 0;
3054 codei = reverse_condition (codei);
3055 }
3056
3057 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
3058 {
3059 if (! can_reverse_comparison_p (ctarget, target))
3060 return 0;
3061 codet = reverse_condition (codet);
3062 }
3063
3064 return (codei == codet
3065 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
3066 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
3067 }
3068 \f
3069 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3070 return non-zero if it is safe to reverse this comparison. It is if our
3071 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3072 this is known to be an integer comparison. */
3073
3074 int
3075 can_reverse_comparison_p (comparison, insn)
3076 rtx comparison;
3077 rtx insn;
3078 {
3079 rtx arg0;
3080
3081 /* If this is not actually a comparison, we can't reverse it. */
3082 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
3083 return 0;
3084
3085 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3086 /* If this is an NE comparison, it is safe to reverse it to an EQ
3087 comparison and vice versa, even for floating point. If no operands
3088 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3089 always false and NE is always true, so the reversal is also valid. */
3090 || flag_fast_math
3091 || GET_CODE (comparison) == NE
3092 || GET_CODE (comparison) == EQ)
3093 return 1;
3094
3095 arg0 = XEXP (comparison, 0);
3096
3097 /* Make sure ARG0 is one of the actual objects being compared. If we
3098 can't do this, we can't be sure the comparison can be reversed.
3099
3100 Handle cc0 and a MODE_CC register. */
3101 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
3102 #ifdef HAVE_cc0
3103 || arg0 == cc0_rtx
3104 #endif
3105 )
3106 {
3107 rtx prev = prev_nonnote_insn (insn);
3108 rtx set = single_set (prev);
3109
3110 if (set == 0 || SET_DEST (set) != arg0)
3111 return 0;
3112
3113 arg0 = SET_SRC (set);
3114
3115 if (GET_CODE (arg0) == COMPARE)
3116 arg0 = XEXP (arg0, 0);
3117 }
3118
3119 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3120 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3121 return (GET_CODE (arg0) == CONST_INT
3122 || (GET_MODE (arg0) != VOIDmode
3123 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
3124 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
3125 }
3126
3127 /* Given an rtx-code for a comparison, return the code
3128 for the negated comparison.
3129 WATCH OUT! reverse_condition is not safe to use on a jump
3130 that might be acting on the results of an IEEE floating point comparison,
3131 because of the special treatment of non-signaling nans in comparisons.
3132 Use can_reverse_comparison_p to be sure. */
3133
3134 enum rtx_code
3135 reverse_condition (code)
3136 enum rtx_code code;
3137 {
3138 switch (code)
3139 {
3140 case EQ:
3141 return NE;
3142
3143 case NE:
3144 return EQ;
3145
3146 case GT:
3147 return LE;
3148
3149 case GE:
3150 return LT;
3151
3152 case LT:
3153 return GE;
3154
3155 case LE:
3156 return GT;
3157
3158 case GTU:
3159 return LEU;
3160
3161 case GEU:
3162 return LTU;
3163
3164 case LTU:
3165 return GEU;
3166
3167 case LEU:
3168 return GTU;
3169
3170 default:
3171 abort ();
3172 return UNKNOWN;
3173 }
3174 }
3175
3176 /* Similar, but return the code when two operands of a comparison are swapped.
3177 This IS safe for IEEE floating-point. */
3178
3179 enum rtx_code
3180 swap_condition (code)
3181 enum rtx_code code;
3182 {
3183 switch (code)
3184 {
3185 case EQ:
3186 case NE:
3187 return code;
3188
3189 case GT:
3190 return LT;
3191
3192 case GE:
3193 return LE;
3194
3195 case LT:
3196 return GT;
3197
3198 case LE:
3199 return GE;
3200
3201 case GTU:
3202 return LTU;
3203
3204 case GEU:
3205 return LEU;
3206
3207 case LTU:
3208 return GTU;
3209
3210 case LEU:
3211 return GEU;
3212
3213 default:
3214 abort ();
3215 return UNKNOWN;
3216 }
3217 }
3218
3219 /* Given a comparison CODE, return the corresponding unsigned comparison.
3220 If CODE is an equality comparison or already an unsigned comparison,
3221 CODE is returned. */
3222
3223 enum rtx_code
3224 unsigned_condition (code)
3225 enum rtx_code code;
3226 {
3227 switch (code)
3228 {
3229 case EQ:
3230 case NE:
3231 case GTU:
3232 case GEU:
3233 case LTU:
3234 case LEU:
3235 return code;
3236
3237 case GT:
3238 return GTU;
3239
3240 case GE:
3241 return GEU;
3242
3243 case LT:
3244 return LTU;
3245
3246 case LE:
3247 return LEU;
3248
3249 default:
3250 abort ();
3251 }
3252 }
3253
3254 /* Similarly, return the signed version of a comparison. */
3255
3256 enum rtx_code
3257 signed_condition (code)
3258 enum rtx_code code;
3259 {
3260 switch (code)
3261 {
3262 case EQ:
3263 case NE:
3264 case GT:
3265 case GE:
3266 case LT:
3267 case LE:
3268 return code;
3269
3270 case GTU:
3271 return GT;
3272
3273 case GEU:
3274 return GE;
3275
3276 case LTU:
3277 return LT;
3278
3279 case LEU:
3280 return LE;
3281
3282 default:
3283 abort ();
3284 }
3285 }
3286 \f
3287 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3288 truth of CODE1 implies the truth of CODE2. */
3289
3290 int
3291 comparison_dominates_p (code1, code2)
3292 enum rtx_code code1, code2;
3293 {
3294 if (code1 == code2)
3295 return 1;
3296
3297 switch (code1)
3298 {
3299 case EQ:
3300 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3301 return 1;
3302 break;
3303
3304 case LT:
3305 if (code2 == LE || code2 == NE)
3306 return 1;
3307 break;
3308
3309 case GT:
3310 if (code2 == GE || code2 == NE)
3311 return 1;
3312 break;
3313
3314 case LTU:
3315 if (code2 == LEU || code2 == NE)
3316 return 1;
3317 break;
3318
3319 case GTU:
3320 if (code2 == GEU || code2 == NE)
3321 return 1;
3322 break;
3323
3324 default:
3325 break;
3326 }
3327
3328 return 0;
3329 }
3330 \f
3331 /* Return 1 if INSN is an unconditional jump and nothing else. */
3332
3333 int
3334 simplejump_p (insn)
3335 rtx insn;
3336 {
3337 return (GET_CODE (insn) == JUMP_INSN
3338 && GET_CODE (PATTERN (insn)) == SET
3339 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3340 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3341 }
3342
3343 /* Return nonzero if INSN is a (possibly) conditional jump
3344 and nothing more. */
3345
3346 int
3347 condjump_p (insn)
3348 rtx insn;
3349 {
3350 register rtx x = PATTERN (insn);
3351 if (GET_CODE (x) != SET)
3352 return 0;
3353 if (GET_CODE (SET_DEST (x)) != PC)
3354 return 0;
3355 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3356 return 1;
3357 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3358 return 0;
3359 if (XEXP (SET_SRC (x), 2) == pc_rtx
3360 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3361 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3362 return 1;
3363 if (XEXP (SET_SRC (x), 1) == pc_rtx
3364 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3365 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3366 return 1;
3367 return 0;
3368 }
3369
3370 /* Return nonzero if INSN is a (possibly) conditional jump
3371 and nothing more. */
3372
3373 int
3374 condjump_in_parallel_p (insn)
3375 rtx insn;
3376 {
3377 register rtx x = PATTERN (insn);
3378
3379 if (GET_CODE (x) != PARALLEL)
3380 return 0;
3381 else
3382 x = XVECEXP (x, 0, 0);
3383
3384 if (GET_CODE (x) != SET)
3385 return 0;
3386 if (GET_CODE (SET_DEST (x)) != PC)
3387 return 0;
3388 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3389 return 1;
3390 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3391 return 0;
3392 if (XEXP (SET_SRC (x), 2) == pc_rtx
3393 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3394 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3395 return 1;
3396 if (XEXP (SET_SRC (x), 1) == pc_rtx
3397 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3398 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3399 return 1;
3400 return 0;
3401 }
3402
3403 #ifdef HAVE_cc0
3404
3405 /* Return 1 if X is an RTX that does nothing but set the condition codes
3406 and CLOBBER or USE registers.
3407 Return -1 if X does explicitly set the condition codes,
3408 but also does other things. */
3409
3410 int
3411 sets_cc0_p (x)
3412 rtx x ATTRIBUTE_UNUSED;
3413 {
3414 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3415 return 1;
3416 if (GET_CODE (x) == PARALLEL)
3417 {
3418 int i;
3419 int sets_cc0 = 0;
3420 int other_things = 0;
3421 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3422 {
3423 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3424 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3425 sets_cc0 = 1;
3426 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3427 other_things = 1;
3428 }
3429 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3430 }
3431 return 0;
3432 }
3433 #endif
3434 \f
3435 /* Follow any unconditional jump at LABEL;
3436 return the ultimate label reached by any such chain of jumps.
3437 If LABEL is not followed by a jump, return LABEL.
3438 If the chain loops or we can't find end, return LABEL,
3439 since that tells caller to avoid changing the insn.
3440
3441 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3442 a USE or CLOBBER. */
3443
3444 rtx
3445 follow_jumps (label)
3446 rtx label;
3447 {
3448 register rtx insn;
3449 register rtx next;
3450 register rtx value = label;
3451 register int depth;
3452
3453 for (depth = 0;
3454 (depth < 10
3455 && (insn = next_active_insn (value)) != 0
3456 && GET_CODE (insn) == JUMP_INSN
3457 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3458 || GET_CODE (PATTERN (insn)) == RETURN)
3459 && (next = NEXT_INSN (insn))
3460 && GET_CODE (next) == BARRIER);
3461 depth++)
3462 {
3463 /* Don't chain through the insn that jumps into a loop
3464 from outside the loop,
3465 since that would create multiple loop entry jumps
3466 and prevent loop optimization. */
3467 rtx tem;
3468 if (!reload_completed)
3469 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3470 if (GET_CODE (tem) == NOTE
3471 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3472 /* ??? Optional. Disables some optimizations, but makes
3473 gcov output more accurate with -O. */
3474 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3475 return value;
3476
3477 /* If we have found a cycle, make the insn jump to itself. */
3478 if (JUMP_LABEL (insn) == label)
3479 return label;
3480
3481 tem = next_active_insn (JUMP_LABEL (insn));
3482 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3483 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3484 break;
3485
3486 value = JUMP_LABEL (insn);
3487 }
3488 if (depth == 10)
3489 return label;
3490 return value;
3491 }
3492
3493 /* Assuming that field IDX of X is a vector of label_refs,
3494 replace each of them by the ultimate label reached by it.
3495 Return nonzero if a change is made.
3496 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3497
3498 static int
3499 tension_vector_labels (x, idx)
3500 register rtx x;
3501 register int idx;
3502 {
3503 int changed = 0;
3504 register int i;
3505 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3506 {
3507 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3508 register rtx nlabel = follow_jumps (olabel);
3509 if (nlabel && nlabel != olabel)
3510 {
3511 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3512 ++LABEL_NUSES (nlabel);
3513 if (--LABEL_NUSES (olabel) == 0)
3514 delete_insn (olabel);
3515 changed = 1;
3516 }
3517 }
3518 return changed;
3519 }
3520 \f
3521 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3522 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3523 in INSN, then store one of them in JUMP_LABEL (INSN).
3524 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3525 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3526 Also, when there are consecutive labels, canonicalize on the last of them.
3527
3528 Note that two labels separated by a loop-beginning note
3529 must be kept distinct if we have not yet done loop-optimization,
3530 because the gap between them is where loop-optimize
3531 will want to move invariant code to. CROSS_JUMP tells us
3532 that loop-optimization is done with.
3533
3534 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3535 two labels distinct if they are separated by only USE or CLOBBER insns. */
3536
3537 static void
3538 mark_jump_label (x, insn, cross_jump)
3539 register rtx x;
3540 rtx insn;
3541 int cross_jump;
3542 {
3543 register RTX_CODE code = GET_CODE (x);
3544 register int i;
3545 register char *fmt;
3546
3547 switch (code)
3548 {
3549 case PC:
3550 case CC0:
3551 case REG:
3552 case SUBREG:
3553 case CONST_INT:
3554 case SYMBOL_REF:
3555 case CONST_DOUBLE:
3556 case CLOBBER:
3557 case CALL:
3558 return;
3559
3560 case MEM:
3561 /* If this is a constant-pool reference, see if it is a label. */
3562 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3563 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3564 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3565 break;
3566
3567 case LABEL_REF:
3568 {
3569 rtx label = XEXP (x, 0);
3570 rtx olabel = label;
3571 rtx note;
3572 rtx next;
3573
3574 if (GET_CODE (label) != CODE_LABEL)
3575 abort ();
3576
3577 /* Ignore references to labels of containing functions. */
3578 if (LABEL_REF_NONLOCAL_P (x))
3579 break;
3580
3581 /* If there are other labels following this one,
3582 replace it with the last of the consecutive labels. */
3583 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3584 {
3585 if (GET_CODE (next) == CODE_LABEL)
3586 label = next;
3587 else if (cross_jump && GET_CODE (next) == INSN
3588 && (GET_CODE (PATTERN (next)) == USE
3589 || GET_CODE (PATTERN (next)) == CLOBBER))
3590 continue;
3591 else if (GET_CODE (next) != NOTE)
3592 break;
3593 else if (! cross_jump
3594 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3595 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3596 /* ??? Optional. Disables some optimizations, but
3597 makes gcov output more accurate with -O. */
3598 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3599 break;
3600 }
3601
3602 XEXP (x, 0) = label;
3603 if (! insn || ! INSN_DELETED_P (insn))
3604 ++LABEL_NUSES (label);
3605
3606 if (insn)
3607 {
3608 if (GET_CODE (insn) == JUMP_INSN)
3609 JUMP_LABEL (insn) = label;
3610
3611 /* If we've changed OLABEL and we had a REG_LABEL note
3612 for it, update it as well. */
3613 else if (label != olabel
3614 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3615 XEXP (note, 0) = label;
3616
3617 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3618 is one. */
3619 else if (! find_reg_note (insn, REG_LABEL, label))
3620 {
3621 /* This code used to ignore labels which refered to dispatch
3622 tables to avoid flow.c generating worse code.
3623
3624 However, in the presense of global optimizations like
3625 gcse which call find_basic_blocks without calling
3626 life_analysis, not recording such labels will lead
3627 to compiler aborts because of inconsistencies in the
3628 flow graph. So we go ahead and record the label.
3629
3630 It may also be the case that the optimization argument
3631 is no longer valid because of the more accurate cfg
3632 we build in find_basic_blocks -- it no longer pessimizes
3633 code when it finds a REG_LABEL note. */
3634 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
3635 REG_NOTES (insn));
3636 }
3637 }
3638 return;
3639 }
3640
3641 /* Do walk the labels in a vector, but not the first operand of an
3642 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3643 case ADDR_VEC:
3644 case ADDR_DIFF_VEC:
3645 if (! INSN_DELETED_P (insn))
3646 {
3647 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3648
3649 for (i = 0; i < XVECLEN (x, eltnum); i++)
3650 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3651 }
3652 return;
3653
3654 default:
3655 break;
3656 }
3657
3658 fmt = GET_RTX_FORMAT (code);
3659 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3660 {
3661 if (fmt[i] == 'e')
3662 mark_jump_label (XEXP (x, i), insn, cross_jump);
3663 else if (fmt[i] == 'E')
3664 {
3665 register int j;
3666 for (j = 0; j < XVECLEN (x, i); j++)
3667 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3668 }
3669 }
3670 }
3671
3672 /* If all INSN does is set the pc, delete it,
3673 and delete the insn that set the condition codes for it
3674 if that's what the previous thing was. */
3675
3676 void
3677 delete_jump (insn)
3678 rtx insn;
3679 {
3680 register rtx set = single_set (insn);
3681
3682 if (set && GET_CODE (SET_DEST (set)) == PC)
3683 delete_computation (insn);
3684 }
3685
3686 /* Delete INSN and recursively delete insns that compute values used only
3687 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3688 If we are running before flow.c, we need do nothing since flow.c will
3689 delete dead code. We also can't know if the registers being used are
3690 dead or not at this point.
3691
3692 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3693 nothing other than set a register that dies in this insn, we can delete
3694 that insn as well.
3695
3696 On machines with CC0, if CC0 is used in this insn, we may be able to
3697 delete the insn that set it. */
3698
3699 static void
3700 delete_computation (insn)
3701 rtx insn;
3702 {
3703 rtx note, next;
3704
3705 #ifdef HAVE_cc0
3706 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3707 {
3708 rtx prev = prev_nonnote_insn (insn);
3709 /* We assume that at this stage
3710 CC's are always set explicitly
3711 and always immediately before the jump that
3712 will use them. So if the previous insn
3713 exists to set the CC's, delete it
3714 (unless it performs auto-increments, etc.). */
3715 if (prev && GET_CODE (prev) == INSN
3716 && sets_cc0_p (PATTERN (prev)))
3717 {
3718 if (sets_cc0_p (PATTERN (prev)) > 0
3719 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3720 delete_computation (prev);
3721 else
3722 /* Otherwise, show that cc0 won't be used. */
3723 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
3724 cc0_rtx, REG_NOTES (prev));
3725 }
3726 }
3727 #endif
3728
3729 for (note = REG_NOTES (insn); note; note = next)
3730 {
3731 rtx our_prev;
3732
3733 next = XEXP (note, 1);
3734
3735 if (REG_NOTE_KIND (note) != REG_DEAD
3736 /* Verify that the REG_NOTE is legitimate. */
3737 || GET_CODE (XEXP (note, 0)) != REG)
3738 continue;
3739
3740 for (our_prev = prev_nonnote_insn (insn);
3741 our_prev && GET_CODE (our_prev) == INSN;
3742 our_prev = prev_nonnote_insn (our_prev))
3743 {
3744 /* If we reach a SEQUENCE, it is too complex to try to
3745 do anything with it, so give up. */
3746 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3747 break;
3748
3749 if (GET_CODE (PATTERN (our_prev)) == USE
3750 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3751 /* reorg creates USEs that look like this. We leave them
3752 alone because reorg needs them for its own purposes. */
3753 break;
3754
3755 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3756 {
3757 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3758 break;
3759
3760 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3761 {
3762 /* If we find a SET of something else, we can't
3763 delete the insn. */
3764
3765 int i;
3766
3767 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3768 {
3769 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3770
3771 if (GET_CODE (part) == SET
3772 && SET_DEST (part) != XEXP (note, 0))
3773 break;
3774 }
3775
3776 if (i == XVECLEN (PATTERN (our_prev), 0))
3777 delete_computation (our_prev);
3778 }
3779 else if (GET_CODE (PATTERN (our_prev)) == SET
3780 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3781 delete_computation (our_prev);
3782
3783 break;
3784 }
3785
3786 /* If OUR_PREV references the register that dies here, it is an
3787 additional use. Hence any prior SET isn't dead. However, this
3788 insn becomes the new place for the REG_DEAD note. */
3789 if (reg_overlap_mentioned_p (XEXP (note, 0),
3790 PATTERN (our_prev)))
3791 {
3792 XEXP (note, 1) = REG_NOTES (our_prev);
3793 REG_NOTES (our_prev) = note;
3794 break;
3795 }
3796 }
3797 }
3798
3799 delete_insn (insn);
3800 }
3801 \f
3802 /* Delete insn INSN from the chain of insns and update label ref counts.
3803 May delete some following insns as a consequence; may even delete
3804 a label elsewhere and insns that follow it.
3805
3806 Returns the first insn after INSN that was not deleted. */
3807
3808 rtx
3809 delete_insn (insn)
3810 register rtx insn;
3811 {
3812 register rtx next = NEXT_INSN (insn);
3813 register rtx prev = PREV_INSN (insn);
3814 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3815 register int dont_really_delete = 0;
3816
3817 while (next && INSN_DELETED_P (next))
3818 next = NEXT_INSN (next);
3819
3820 /* This insn is already deleted => return first following nondeleted. */
3821 if (INSN_DELETED_P (insn))
3822 return next;
3823
3824 /* Don't delete user-declared labels. Convert them to special NOTEs
3825 instead. */
3826 if (was_code_label && LABEL_NAME (insn) != 0
3827 && optimize && ! dont_really_delete)
3828 {
3829 PUT_CODE (insn, NOTE);
3830 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3831 NOTE_SOURCE_FILE (insn) = 0;
3832 dont_really_delete = 1;
3833 }
3834 else
3835 /* Mark this insn as deleted. */
3836 INSN_DELETED_P (insn) = 1;
3837
3838 /* If this is an unconditional jump, delete it from the jump chain. */
3839 if (simplejump_p (insn))
3840 delete_from_jump_chain (insn);
3841
3842 /* If instruction is followed by a barrier,
3843 delete the barrier too. */
3844
3845 if (next != 0 && GET_CODE (next) == BARRIER)
3846 {
3847 INSN_DELETED_P (next) = 1;
3848 next = NEXT_INSN (next);
3849 }
3850
3851 /* Patch out INSN (and the barrier if any) */
3852
3853 if (optimize && ! dont_really_delete)
3854 {
3855 if (prev)
3856 {
3857 NEXT_INSN (prev) = next;
3858 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3859 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3860 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3861 }
3862
3863 if (next)
3864 {
3865 PREV_INSN (next) = prev;
3866 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3867 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3868 }
3869
3870 if (prev && NEXT_INSN (prev) == 0)
3871 set_last_insn (prev);
3872 }
3873
3874 /* If deleting a jump, decrement the count of the label,
3875 and delete the label if it is now unused. */
3876
3877 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3878 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3879 {
3880 /* This can delete NEXT or PREV,
3881 either directly if NEXT is JUMP_LABEL (INSN),
3882 or indirectly through more levels of jumps. */
3883 delete_insn (JUMP_LABEL (insn));
3884 /* I feel a little doubtful about this loop,
3885 but I see no clean and sure alternative way
3886 to find the first insn after INSN that is not now deleted.
3887 I hope this works. */
3888 while (next && INSN_DELETED_P (next))
3889 next = NEXT_INSN (next);
3890 return next;
3891 }
3892
3893 /* Likewise if we're deleting a dispatch table. */
3894
3895 if (GET_CODE (insn) == JUMP_INSN
3896 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3897 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3898 {
3899 rtx pat = PATTERN (insn);
3900 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3901 int len = XVECLEN (pat, diff_vec_p);
3902
3903 for (i = 0; i < len; i++)
3904 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3905 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3906 while (next && INSN_DELETED_P (next))
3907 next = NEXT_INSN (next);
3908 return next;
3909 }
3910
3911 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3912 prev = PREV_INSN (prev);
3913
3914 /* If INSN was a label and a dispatch table follows it,
3915 delete the dispatch table. The tablejump must have gone already.
3916 It isn't useful to fall through into a table. */
3917
3918 if (was_code_label
3919 && NEXT_INSN (insn) != 0
3920 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3921 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3922 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3923 next = delete_insn (NEXT_INSN (insn));
3924
3925 /* If INSN was a label, delete insns following it if now unreachable. */
3926
3927 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3928 {
3929 register RTX_CODE code;
3930 while (next != 0
3931 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3932 || code == NOTE || code == BARRIER
3933 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3934 {
3935 if (code == NOTE
3936 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3937 next = NEXT_INSN (next);
3938 /* Keep going past other deleted labels to delete what follows. */
3939 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3940 next = NEXT_INSN (next);
3941 else
3942 /* Note: if this deletes a jump, it can cause more
3943 deletion of unreachable code, after a different label.
3944 As long as the value from this recursive call is correct,
3945 this invocation functions correctly. */
3946 next = delete_insn (next);
3947 }
3948 }
3949
3950 return next;
3951 }
3952
3953 /* Advance from INSN till reaching something not deleted
3954 then return that. May return INSN itself. */
3955
3956 rtx
3957 next_nondeleted_insn (insn)
3958 rtx insn;
3959 {
3960 while (INSN_DELETED_P (insn))
3961 insn = NEXT_INSN (insn);
3962 return insn;
3963 }
3964 \f
3965 /* Delete a range of insns from FROM to TO, inclusive.
3966 This is for the sake of peephole optimization, so assume
3967 that whatever these insns do will still be done by a new
3968 peephole insn that will replace them. */
3969
3970 void
3971 delete_for_peephole (from, to)
3972 register rtx from, to;
3973 {
3974 register rtx insn = from;
3975
3976 while (1)
3977 {
3978 register rtx next = NEXT_INSN (insn);
3979 register rtx prev = PREV_INSN (insn);
3980
3981 if (GET_CODE (insn) != NOTE)
3982 {
3983 INSN_DELETED_P (insn) = 1;
3984
3985 /* Patch this insn out of the chain. */
3986 /* We don't do this all at once, because we
3987 must preserve all NOTEs. */
3988 if (prev)
3989 NEXT_INSN (prev) = next;
3990
3991 if (next)
3992 PREV_INSN (next) = prev;
3993 }
3994
3995 if (insn == to)
3996 break;
3997 insn = next;
3998 }
3999
4000 /* Note that if TO is an unconditional jump
4001 we *do not* delete the BARRIER that follows,
4002 since the peephole that replaces this sequence
4003 is also an unconditional jump in that case. */
4004 }
4005 \f
4006 /* Invert the condition of the jump JUMP, and make it jump
4007 to label NLABEL instead of where it jumps now. */
4008
4009 int
4010 invert_jump (jump, nlabel)
4011 rtx jump, nlabel;
4012 {
4013 /* We have to either invert the condition and change the label or
4014 do neither. Either operation could fail. We first try to invert
4015 the jump. If that succeeds, we try changing the label. If that fails,
4016 we invert the jump back to what it was. */
4017
4018 if (! invert_exp (PATTERN (jump), jump))
4019 return 0;
4020
4021 if (redirect_jump (jump, nlabel))
4022 {
4023 if (flag_branch_probabilities)
4024 {
4025 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
4026
4027 /* An inverted jump means that a probability taken becomes a
4028 probability not taken. Subtract the branch probability from the
4029 probability base to convert it back to a taken probability.
4030 (We don't flip the probability on a branch that's never taken. */
4031 if (note && XINT (XEXP (note, 0), 0) >= 0)
4032 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
4033 }
4034
4035 return 1;
4036 }
4037
4038 if (! invert_exp (PATTERN (jump), jump))
4039 /* This should just be putting it back the way it was. */
4040 abort ();
4041
4042 return 0;
4043 }
4044
4045 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4046
4047 Return 1 if we can do so, 0 if we cannot find a way to do so that
4048 matches a pattern. */
4049
4050 int
4051 invert_exp (x, insn)
4052 rtx x;
4053 rtx insn;
4054 {
4055 register RTX_CODE code;
4056 register int i;
4057 register char *fmt;
4058
4059 code = GET_CODE (x);
4060
4061 if (code == IF_THEN_ELSE)
4062 {
4063 register rtx comp = XEXP (x, 0);
4064 register rtx tem;
4065
4066 /* We can do this in two ways: The preferable way, which can only
4067 be done if this is not an integer comparison, is to reverse
4068 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4069 of the IF_THEN_ELSE. If we can't do either, fail. */
4070
4071 if (can_reverse_comparison_p (comp, insn)
4072 && validate_change (insn, &XEXP (x, 0),
4073 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
4074 GET_MODE (comp), XEXP (comp, 0),
4075 XEXP (comp, 1)), 0))
4076 return 1;
4077
4078 tem = XEXP (x, 1);
4079 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
4080 validate_change (insn, &XEXP (x, 2), tem, 1);
4081 return apply_change_group ();
4082 }
4083
4084 fmt = GET_RTX_FORMAT (code);
4085 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4086 {
4087 if (fmt[i] == 'e')
4088 if (! invert_exp (XEXP (x, i), insn))
4089 return 0;
4090 if (fmt[i] == 'E')
4091 {
4092 register int j;
4093 for (j = 0; j < XVECLEN (x, i); j++)
4094 if (!invert_exp (XVECEXP (x, i, j), insn))
4095 return 0;
4096 }
4097 }
4098
4099 return 1;
4100 }
4101 \f
4102 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4103 If the old jump target label is unused as a result,
4104 it and the code following it may be deleted.
4105
4106 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4107 RETURN insn.
4108
4109 The return value will be 1 if the change was made, 0 if it wasn't (this
4110 can only occur for NLABEL == 0). */
4111
4112 int
4113 redirect_jump (jump, nlabel)
4114 rtx jump, nlabel;
4115 {
4116 register rtx olabel = JUMP_LABEL (jump);
4117
4118 if (nlabel == olabel)
4119 return 1;
4120
4121 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
4122 return 0;
4123
4124 /* If this is an unconditional branch, delete it from the jump_chain of
4125 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4126 have UID's in range and JUMP_CHAIN is valid). */
4127 if (jump_chain && (simplejump_p (jump)
4128 || GET_CODE (PATTERN (jump)) == RETURN))
4129 {
4130 int label_index = nlabel ? INSN_UID (nlabel) : 0;
4131
4132 delete_from_jump_chain (jump);
4133 if (label_index < max_jump_chain
4134 && INSN_UID (jump) < max_jump_chain)
4135 {
4136 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
4137 jump_chain[label_index] = jump;
4138 }
4139 }
4140
4141 JUMP_LABEL (jump) = nlabel;
4142 if (nlabel)
4143 ++LABEL_NUSES (nlabel);
4144
4145 if (olabel && --LABEL_NUSES (olabel) == 0)
4146 delete_insn (olabel);
4147
4148 return 1;
4149 }
4150
4151 /* Delete the instruction JUMP from any jump chain it might be on. */
4152
4153 static void
4154 delete_from_jump_chain (jump)
4155 rtx jump;
4156 {
4157 int index;
4158 rtx olabel = JUMP_LABEL (jump);
4159
4160 /* Handle unconditional jumps. */
4161 if (jump_chain && olabel != 0
4162 && INSN_UID (olabel) < max_jump_chain
4163 && simplejump_p (jump))
4164 index = INSN_UID (olabel);
4165 /* Handle return insns. */
4166 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
4167 index = 0;
4168 else return;
4169
4170 if (jump_chain[index] == jump)
4171 jump_chain[index] = jump_chain[INSN_UID (jump)];
4172 else
4173 {
4174 rtx insn;
4175
4176 for (insn = jump_chain[index];
4177 insn != 0;
4178 insn = jump_chain[INSN_UID (insn)])
4179 if (jump_chain[INSN_UID (insn)] == jump)
4180 {
4181 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
4182 break;
4183 }
4184 }
4185 }
4186
4187 /* If NLABEL is nonzero, throughout the rtx at LOC,
4188 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4189 zero, alter (RETURN) to (LABEL_REF NLABEL).
4190
4191 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4192 validity with validate_change. Convert (set (pc) (label_ref olabel))
4193 to (return).
4194
4195 Return 0 if we found a change we would like to make but it is invalid.
4196 Otherwise, return 1. */
4197
4198 int
4199 redirect_exp (loc, olabel, nlabel, insn)
4200 rtx *loc;
4201 rtx olabel, nlabel;
4202 rtx insn;
4203 {
4204 register rtx x = *loc;
4205 register RTX_CODE code = GET_CODE (x);
4206 register int i;
4207 register char *fmt;
4208
4209 if (code == LABEL_REF)
4210 {
4211 if (XEXP (x, 0) == olabel)
4212 {
4213 if (nlabel)
4214 XEXP (x, 0) = nlabel;
4215 else
4216 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4217 return 1;
4218 }
4219 }
4220 else if (code == RETURN && olabel == 0)
4221 {
4222 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4223 if (loc == &PATTERN (insn))
4224 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4225 return validate_change (insn, loc, x, 0);
4226 }
4227
4228 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4229 && GET_CODE (SET_SRC (x)) == LABEL_REF
4230 && XEXP (SET_SRC (x), 0) == olabel)
4231 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4232
4233 fmt = GET_RTX_FORMAT (code);
4234 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4235 {
4236 if (fmt[i] == 'e')
4237 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4238 return 0;
4239 if (fmt[i] == 'E')
4240 {
4241 register int j;
4242 for (j = 0; j < XVECLEN (x, i); j++)
4243 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4244 return 0;
4245 }
4246 }
4247
4248 return 1;
4249 }
4250 \f
4251 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4252
4253 If the old jump target label (before the dispatch table) becomes unused,
4254 it and the dispatch table may be deleted. In that case, find the insn
4255 before the jump references that label and delete it and logical successors
4256 too. */
4257
4258 static void
4259 redirect_tablejump (jump, nlabel)
4260 rtx jump, nlabel;
4261 {
4262 register rtx olabel = JUMP_LABEL (jump);
4263
4264 /* Add this jump to the jump_chain of NLABEL. */
4265 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4266 && INSN_UID (jump) < max_jump_chain)
4267 {
4268 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4269 jump_chain[INSN_UID (nlabel)] = jump;
4270 }
4271
4272 PATTERN (jump) = gen_jump (nlabel);
4273 JUMP_LABEL (jump) = nlabel;
4274 ++LABEL_NUSES (nlabel);
4275 INSN_CODE (jump) = -1;
4276
4277 if (--LABEL_NUSES (olabel) == 0)
4278 {
4279 delete_labelref_insn (jump, olabel, 0);
4280 delete_insn (olabel);
4281 }
4282 }
4283
4284 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4285 If we found one, delete it and then delete this insn if DELETE_THIS is
4286 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4287
4288 static int
4289 delete_labelref_insn (insn, label, delete_this)
4290 rtx insn, label;
4291 int delete_this;
4292 {
4293 int deleted = 0;
4294 rtx link;
4295
4296 if (GET_CODE (insn) != NOTE
4297 && reg_mentioned_p (label, PATTERN (insn)))
4298 {
4299 if (delete_this)
4300 {
4301 delete_insn (insn);
4302 deleted = 1;
4303 }
4304 else
4305 return 1;
4306 }
4307
4308 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4309 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4310 {
4311 if (delete_this)
4312 {
4313 delete_insn (insn);
4314 deleted = 1;
4315 }
4316 else
4317 return 1;
4318 }
4319
4320 return deleted;
4321 }
4322 \f
4323 /* Like rtx_equal_p except that it considers two REGs as equal
4324 if they renumber to the same value and considers two commutative
4325 operations to be the same if the order of the operands has been
4326 reversed.
4327
4328 ??? Addition is not commutative on the PA due to the weird implicit
4329 space register selection rules for memory addresses. Therefore, we
4330 don't consider a + b == b + a.
4331
4332 We could/should make this test a little tighter. Possibly only
4333 disabling it on the PA via some backend macro or only disabling this
4334 case when the PLUS is inside a MEM. */
4335
4336 int
4337 rtx_renumbered_equal_p (x, y)
4338 rtx x, y;
4339 {
4340 register int i;
4341 register RTX_CODE code = GET_CODE (x);
4342 register char *fmt;
4343
4344 if (x == y)
4345 return 1;
4346
4347 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4348 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4349 && GET_CODE (SUBREG_REG (y)) == REG)))
4350 {
4351 int reg_x = -1, reg_y = -1;
4352 int word_x = 0, word_y = 0;
4353
4354 if (GET_MODE (x) != GET_MODE (y))
4355 return 0;
4356
4357 /* If we haven't done any renumbering, don't
4358 make any assumptions. */
4359 if (reg_renumber == 0)
4360 return rtx_equal_p (x, y);
4361
4362 if (code == SUBREG)
4363 {
4364 reg_x = REGNO (SUBREG_REG (x));
4365 word_x = SUBREG_WORD (x);
4366
4367 if (reg_renumber[reg_x] >= 0)
4368 {
4369 reg_x = reg_renumber[reg_x] + word_x;
4370 word_x = 0;
4371 }
4372 }
4373
4374 else
4375 {
4376 reg_x = REGNO (x);
4377 if (reg_renumber[reg_x] >= 0)
4378 reg_x = reg_renumber[reg_x];
4379 }
4380
4381 if (GET_CODE (y) == SUBREG)
4382 {
4383 reg_y = REGNO (SUBREG_REG (y));
4384 word_y = SUBREG_WORD (y);
4385
4386 if (reg_renumber[reg_y] >= 0)
4387 {
4388 reg_y = reg_renumber[reg_y];
4389 word_y = 0;
4390 }
4391 }
4392
4393 else
4394 {
4395 reg_y = REGNO (y);
4396 if (reg_renumber[reg_y] >= 0)
4397 reg_y = reg_renumber[reg_y];
4398 }
4399
4400 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4401 }
4402
4403 /* Now we have disposed of all the cases
4404 in which different rtx codes can match. */
4405 if (code != GET_CODE (y))
4406 return 0;
4407
4408 switch (code)
4409 {
4410 case PC:
4411 case CC0:
4412 case ADDR_VEC:
4413 case ADDR_DIFF_VEC:
4414 return 0;
4415
4416 case CONST_INT:
4417 return INTVAL (x) == INTVAL (y);
4418
4419 case LABEL_REF:
4420 /* We can't assume nonlocal labels have their following insns yet. */
4421 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4422 return XEXP (x, 0) == XEXP (y, 0);
4423
4424 /* Two label-refs are equivalent if they point at labels
4425 in the same position in the instruction stream. */
4426 return (next_real_insn (XEXP (x, 0))
4427 == next_real_insn (XEXP (y, 0)));
4428
4429 case SYMBOL_REF:
4430 return XSTR (x, 0) == XSTR (y, 0);
4431
4432 default:
4433 break;
4434 }
4435
4436 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4437
4438 if (GET_MODE (x) != GET_MODE (y))
4439 return 0;
4440
4441 /* For commutative operations, the RTX match if the operand match in any
4442 order. Also handle the simple binary and unary cases without a loop.
4443
4444 ??? Don't consider PLUS a commutative operator; see comments above. */
4445 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4446 && code != PLUS)
4447 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4448 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4449 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4450 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4451 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4452 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4453 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4454 else if (GET_RTX_CLASS (code) == '1')
4455 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4456
4457 /* Compare the elements. If any pair of corresponding elements
4458 fail to match, return 0 for the whole things. */
4459
4460 fmt = GET_RTX_FORMAT (code);
4461 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4462 {
4463 register int j;
4464 switch (fmt[i])
4465 {
4466 case 'w':
4467 if (XWINT (x, i) != XWINT (y, i))
4468 return 0;
4469 break;
4470
4471 case 'i':
4472 if (XINT (x, i) != XINT (y, i))
4473 return 0;
4474 break;
4475
4476 case 's':
4477 if (strcmp (XSTR (x, i), XSTR (y, i)))
4478 return 0;
4479 break;
4480
4481 case 'e':
4482 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4483 return 0;
4484 break;
4485
4486 case 'u':
4487 if (XEXP (x, i) != XEXP (y, i))
4488 return 0;
4489 /* fall through. */
4490 case '0':
4491 break;
4492
4493 case 'E':
4494 if (XVECLEN (x, i) != XVECLEN (y, i))
4495 return 0;
4496 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4497 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4498 return 0;
4499 break;
4500
4501 default:
4502 abort ();
4503 }
4504 }
4505 return 1;
4506 }
4507 \f
4508 /* If X is a hard register or equivalent to one or a subregister of one,
4509 return the hard register number. If X is a pseudo register that was not
4510 assigned a hard register, return the pseudo register number. Otherwise,
4511 return -1. Any rtx is valid for X. */
4512
4513 int
4514 true_regnum (x)
4515 rtx x;
4516 {
4517 if (GET_CODE (x) == REG)
4518 {
4519 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4520 return reg_renumber[REGNO (x)];
4521 return REGNO (x);
4522 }
4523 if (GET_CODE (x) == SUBREG)
4524 {
4525 int base = true_regnum (SUBREG_REG (x));
4526 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4527 return SUBREG_WORD (x) + base;
4528 }
4529 return -1;
4530 }
4531 \f
4532 /* Optimize code of the form:
4533
4534 for (x = a[i]; x; ...)
4535 ...
4536 for (x = a[i]; x; ...)
4537 ...
4538 foo:
4539
4540 Loop optimize will change the above code into
4541
4542 if (x = a[i])
4543 for (;;)
4544 { ...; if (! (x = ...)) break; }
4545 if (x = a[i])
4546 for (;;)
4547 { ...; if (! (x = ...)) break; }
4548 foo:
4549
4550 In general, if the first test fails, the program can branch
4551 directly to `foo' and skip the second try which is doomed to fail.
4552 We run this after loop optimization and before flow analysis. */
4553
4554 /* When comparing the insn patterns, we track the fact that different
4555 pseudo-register numbers may have been used in each computation.
4556 The following array stores an equivalence -- same_regs[I] == J means
4557 that pseudo register I was used in the first set of tests in a context
4558 where J was used in the second set. We also count the number of such
4559 pending equivalences. If nonzero, the expressions really aren't the
4560 same. */
4561
4562 static int *same_regs;
4563
4564 static int num_same_regs;
4565
4566 /* Track any registers modified between the target of the first jump and
4567 the second jump. They never compare equal. */
4568
4569 static char *modified_regs;
4570
4571 /* Record if memory was modified. */
4572
4573 static int modified_mem;
4574
4575 /* Called via note_stores on each insn between the target of the first
4576 branch and the second branch. It marks any changed registers. */
4577
4578 static void
4579 mark_modified_reg (dest, x)
4580 rtx dest;
4581 rtx x ATTRIBUTE_UNUSED;
4582 {
4583 int regno, i;
4584
4585 if (GET_CODE (dest) == SUBREG)
4586 dest = SUBREG_REG (dest);
4587
4588 if (GET_CODE (dest) == MEM)
4589 modified_mem = 1;
4590
4591 if (GET_CODE (dest) != REG)
4592 return;
4593
4594 regno = REGNO (dest);
4595 if (regno >= FIRST_PSEUDO_REGISTER)
4596 modified_regs[regno] = 1;
4597 else
4598 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4599 modified_regs[regno + i] = 1;
4600 }
4601
4602 /* F is the first insn in the chain of insns. */
4603
4604 void
4605 thread_jumps (f, max_reg, flag_before_loop)
4606 rtx f;
4607 int max_reg;
4608 int flag_before_loop;
4609 {
4610 /* Basic algorithm is to find a conditional branch,
4611 the label it may branch to, and the branch after
4612 that label. If the two branches test the same condition,
4613 walk back from both branch paths until the insn patterns
4614 differ, or code labels are hit. If we make it back to
4615 the target of the first branch, then we know that the first branch
4616 will either always succeed or always fail depending on the relative
4617 senses of the two branches. So adjust the first branch accordingly
4618 in this case. */
4619
4620 rtx label, b1, b2, t1, t2;
4621 enum rtx_code code1, code2;
4622 rtx b1op0, b1op1, b2op0, b2op1;
4623 int changed = 1;
4624 int i;
4625 int *all_reset;
4626
4627 /* Allocate register tables and quick-reset table. */
4628 modified_regs = (char *) alloca (max_reg * sizeof (char));
4629 same_regs = (int *) alloca (max_reg * sizeof (int));
4630 all_reset = (int *) alloca (max_reg * sizeof (int));
4631 for (i = 0; i < max_reg; i++)
4632 all_reset[i] = -1;
4633
4634 while (changed)
4635 {
4636 changed = 0;
4637
4638 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4639 {
4640 /* Get to a candidate branch insn. */
4641 if (GET_CODE (b1) != JUMP_INSN
4642 || ! condjump_p (b1) || simplejump_p (b1)
4643 || JUMP_LABEL (b1) == 0)
4644 continue;
4645
4646 bzero (modified_regs, max_reg * sizeof (char));
4647 modified_mem = 0;
4648
4649 bcopy ((char *) all_reset, (char *) same_regs,
4650 max_reg * sizeof (int));
4651 num_same_regs = 0;
4652
4653 label = JUMP_LABEL (b1);
4654
4655 /* Look for a branch after the target. Record any registers and
4656 memory modified between the target and the branch. Stop when we
4657 get to a label since we can't know what was changed there. */
4658 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4659 {
4660 if (GET_CODE (b2) == CODE_LABEL)
4661 break;
4662
4663 else if (GET_CODE (b2) == JUMP_INSN)
4664 {
4665 /* If this is an unconditional jump and is the only use of
4666 its target label, we can follow it. */
4667 if (simplejump_p (b2)
4668 && JUMP_LABEL (b2) != 0
4669 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4670 {
4671 b2 = JUMP_LABEL (b2);
4672 continue;
4673 }
4674 else
4675 break;
4676 }
4677
4678 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4679 continue;
4680
4681 if (GET_CODE (b2) == CALL_INSN)
4682 {
4683 modified_mem = 1;
4684 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4685 if (call_used_regs[i] && ! fixed_regs[i]
4686 && i != STACK_POINTER_REGNUM
4687 && i != FRAME_POINTER_REGNUM
4688 && i != HARD_FRAME_POINTER_REGNUM
4689 && i != ARG_POINTER_REGNUM)
4690 modified_regs[i] = 1;
4691 }
4692
4693 note_stores (PATTERN (b2), mark_modified_reg);
4694 }
4695
4696 /* Check the next candidate branch insn from the label
4697 of the first. */
4698 if (b2 == 0
4699 || GET_CODE (b2) != JUMP_INSN
4700 || b2 == b1
4701 || ! condjump_p (b2)
4702 || simplejump_p (b2))
4703 continue;
4704
4705 /* Get the comparison codes and operands, reversing the
4706 codes if appropriate. If we don't have comparison codes,
4707 we can't do anything. */
4708 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4709 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4710 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4711 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4712 code1 = reverse_condition (code1);
4713
4714 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4715 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4716 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4717 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4718 code2 = reverse_condition (code2);
4719
4720 /* If they test the same things and knowing that B1 branches
4721 tells us whether or not B2 branches, check if we
4722 can thread the branch. */
4723 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4724 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4725 && (comparison_dominates_p (code1, code2)
4726 || (comparison_dominates_p (code1, reverse_condition (code2))
4727 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
4728 0),
4729 b1))))
4730 {
4731 t1 = prev_nonnote_insn (b1);
4732 t2 = prev_nonnote_insn (b2);
4733
4734 while (t1 != 0 && t2 != 0)
4735 {
4736 if (t2 == label)
4737 {
4738 /* We have reached the target of the first branch.
4739 If there are no pending register equivalents,
4740 we know that this branch will either always
4741 succeed (if the senses of the two branches are
4742 the same) or always fail (if not). */
4743 rtx new_label;
4744
4745 if (num_same_regs != 0)
4746 break;
4747
4748 if (comparison_dominates_p (code1, code2))
4749 new_label = JUMP_LABEL (b2);
4750 else
4751 new_label = get_label_after (b2);
4752
4753 if (JUMP_LABEL (b1) != new_label)
4754 {
4755 rtx prev = PREV_INSN (new_label);
4756
4757 if (flag_before_loop
4758 && GET_CODE (prev) == NOTE
4759 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4760 {
4761 /* Don't thread to the loop label. If a loop
4762 label is reused, loop optimization will
4763 be disabled for that loop. */
4764 new_label = gen_label_rtx ();
4765 emit_label_after (new_label, PREV_INSN (prev));
4766 }
4767 changed |= redirect_jump (b1, new_label);
4768 }
4769 break;
4770 }
4771
4772 /* If either of these is not a normal insn (it might be
4773 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4774 have already been skipped above.) Similarly, fail
4775 if the insns are different. */
4776 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4777 || recog_memoized (t1) != recog_memoized (t2)
4778 || ! rtx_equal_for_thread_p (PATTERN (t1),
4779 PATTERN (t2), t2))
4780 break;
4781
4782 t1 = prev_nonnote_insn (t1);
4783 t2 = prev_nonnote_insn (t2);
4784 }
4785 }
4786 }
4787 }
4788 }
4789 \f
4790 /* This is like RTX_EQUAL_P except that it knows about our handling of
4791 possibly equivalent registers and knows to consider volatile and
4792 modified objects as not equal.
4793
4794 YINSN is the insn containing Y. */
4795
4796 int
4797 rtx_equal_for_thread_p (x, y, yinsn)
4798 rtx x, y;
4799 rtx yinsn;
4800 {
4801 register int i;
4802 register int j;
4803 register enum rtx_code code;
4804 register char *fmt;
4805
4806 code = GET_CODE (x);
4807 /* Rtx's of different codes cannot be equal. */
4808 if (code != GET_CODE (y))
4809 return 0;
4810
4811 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4812 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4813
4814 if (GET_MODE (x) != GET_MODE (y))
4815 return 0;
4816
4817 /* For floating-point, consider everything unequal. This is a bit
4818 pessimistic, but this pass would only rarely do anything for FP
4819 anyway. */
4820 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4821 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
4822 return 0;
4823
4824 /* For commutative operations, the RTX match if the operand match in any
4825 order. Also handle the simple binary and unary cases without a loop. */
4826 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4827 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4828 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4829 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4830 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4831 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4832 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4833 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4834 else if (GET_RTX_CLASS (code) == '1')
4835 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4836
4837 /* Handle special-cases first. */
4838 switch (code)
4839 {
4840 case REG:
4841 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4842 return 1;
4843
4844 /* If neither is user variable or hard register, check for possible
4845 equivalence. */
4846 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4847 || REGNO (x) < FIRST_PSEUDO_REGISTER
4848 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4849 return 0;
4850
4851 if (same_regs[REGNO (x)] == -1)
4852 {
4853 same_regs[REGNO (x)] = REGNO (y);
4854 num_same_regs++;
4855
4856 /* If this is the first time we are seeing a register on the `Y'
4857 side, see if it is the last use. If not, we can't thread the
4858 jump, so mark it as not equivalent. */
4859 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4860 return 0;
4861
4862 return 1;
4863 }
4864 else
4865 return (same_regs[REGNO (x)] == REGNO (y));
4866
4867 break;
4868
4869 case MEM:
4870 /* If memory modified or either volatile, not equivalent.
4871 Else, check address. */
4872 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4873 return 0;
4874
4875 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4876
4877 case ASM_INPUT:
4878 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4879 return 0;
4880
4881 break;
4882
4883 case SET:
4884 /* Cancel a pending `same_regs' if setting equivalenced registers.
4885 Then process source. */
4886 if (GET_CODE (SET_DEST (x)) == REG
4887 && GET_CODE (SET_DEST (y)) == REG)
4888 {
4889 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4890 {
4891 same_regs[REGNO (SET_DEST (x))] = -1;
4892 num_same_regs--;
4893 }
4894 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4895 return 0;
4896 }
4897 else
4898 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4899 return 0;
4900
4901 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4902
4903 case LABEL_REF:
4904 return XEXP (x, 0) == XEXP (y, 0);
4905
4906 case SYMBOL_REF:
4907 return XSTR (x, 0) == XSTR (y, 0);
4908
4909 default:
4910 break;
4911 }
4912
4913 if (x == y)
4914 return 1;
4915
4916 fmt = GET_RTX_FORMAT (code);
4917 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4918 {
4919 switch (fmt[i])
4920 {
4921 case 'w':
4922 if (XWINT (x, i) != XWINT (y, i))
4923 return 0;
4924 break;
4925
4926 case 'n':
4927 case 'i':
4928 if (XINT (x, i) != XINT (y, i))
4929 return 0;
4930 break;
4931
4932 case 'V':
4933 case 'E':
4934 /* Two vectors must have the same length. */
4935 if (XVECLEN (x, i) != XVECLEN (y, i))
4936 return 0;
4937
4938 /* And the corresponding elements must match. */
4939 for (j = 0; j < XVECLEN (x, i); j++)
4940 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4941 XVECEXP (y, i, j), yinsn) == 0)
4942 return 0;
4943 break;
4944
4945 case 'e':
4946 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4947 return 0;
4948 break;
4949
4950 case 'S':
4951 case 's':
4952 if (strcmp (XSTR (x, i), XSTR (y, i)))
4953 return 0;
4954 break;
4955
4956 case 'u':
4957 /* These are just backpointers, so they don't matter. */
4958 break;
4959
4960 case '0':
4961 break;
4962
4963 /* It is believed that rtx's at this level will never
4964 contain anything but integers and other rtx's,
4965 except for within LABEL_REFs and SYMBOL_REFs. */
4966 default:
4967 abort ();
4968 }
4969 }
4970 return 1;
4971 }
4972 \f
4973
4974 #ifndef HAVE_cc0
4975 /* Return the insn that NEW can be safely inserted in front of starting at
4976 the jump insn INSN. Return 0 if it is not safe to do this jump
4977 optimization. Note that NEW must contain a single set. */
4978
4979 static rtx
4980 find_insert_position (insn, new)
4981 rtx insn;
4982 rtx new;
4983 {
4984 int i;
4985 rtx prev;
4986
4987 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
4988 if (GET_CODE (PATTERN (new)) != PARALLEL)
4989 return insn;
4990
4991 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
4992 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
4993 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
4994 insn))
4995 break;
4996
4997 if (i < 0)
4998 return insn;
4999
5000 /* There is a good chance that the previous insn PREV sets the thing
5001 being clobbered (often the CC in a hard reg). If PREV does not
5002 use what NEW sets, we can insert NEW before PREV. */
5003
5004 prev = prev_active_insn (insn);
5005 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5006 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5007 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5008 insn)
5009 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5010 prev))
5011 return 0;
5012
5013 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
5014 }
5015 #endif /* !HAVE_cc0 */
GNU Compiler Collection
This page took 0.275222 seconds and 6 git commands to generate.