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jump.c (jump_optimize_1): Swap the incscc and the conditional mode detection code
[gcc.git] / gcc / jump.c
1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-98, 1999 Free Software Foundation, Inc.
3
4 This file is part of GNU CC.
5
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
20
21
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
25
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
30
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
37 at by later passes.
38
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
43
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
46
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
50
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
53
54 #include "config.h"
55 #include "system.h"
56 #include "rtl.h"
57 #include "tm_p.h"
58 #include "flags.h"
59 #include "hard-reg-set.h"
60 #include "regs.h"
61 #include "insn-config.h"
62 #include "insn-flags.h"
63 #include "insn-attr.h"
64 #include "recog.h"
65 #include "function.h"
66 #include "expr.h"
67 #include "real.h"
68 #include "except.h"
69 #include "toplev.h"
70
71 /* ??? Eventually must record somehow the labels used by jumps
72 from nested functions. */
73 /* Pre-record the next or previous real insn for each label?
74 No, this pass is very fast anyway. */
75 /* Condense consecutive labels?
76 This would make life analysis faster, maybe. */
77 /* Optimize jump y; x: ... y: jumpif... x?
78 Don't know if it is worth bothering with. */
79 /* Optimize two cases of conditional jump to conditional jump?
80 This can never delete any instruction or make anything dead,
81 or even change what is live at any point.
82 So perhaps let combiner do it. */
83
84 /* Vector indexed by uid.
85 For each CODE_LABEL, index by its uid to get first unconditional jump
86 that jumps to the label.
87 For each JUMP_INSN, index by its uid to get the next unconditional jump
88 that jumps to the same label.
89 Element 0 is the start of a chain of all return insns.
90 (It is safe to use element 0 because insn uid 0 is not used. */
91
92 static rtx *jump_chain;
93
94 /* Maximum index in jump_chain. */
95
96 static int max_jump_chain;
97
98 /* Set nonzero by jump_optimize if control can fall through
99 to the end of the function. */
100 int can_reach_end;
101
102 /* Indicates whether death notes are significant in cross jump analysis.
103 Normally they are not significant, because of A and B jump to C,
104 and R dies in A, it must die in B. But this might not be true after
105 stack register conversion, and we must compare death notes in that
106 case. */
107
108 static int cross_jump_death_matters = 0;
109
110 static int init_label_info PROTO((rtx));
111 static void delete_barrier_successors PROTO((rtx));
112 static void mark_all_labels PROTO((rtx, int));
113 static rtx delete_unreferenced_labels PROTO((rtx));
114 static void delete_noop_moves PROTO((rtx));
115 static int calculate_can_reach_end PROTO((rtx, int, int));
116 static int duplicate_loop_exit_test PROTO((rtx));
117 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
118 static void do_cross_jump PROTO((rtx, rtx, rtx));
119 static int jump_back_p PROTO((rtx, rtx));
120 static int tension_vector_labels PROTO((rtx, int));
121 static void mark_jump_label PROTO((rtx, rtx, int));
122 static void delete_computation PROTO((rtx));
123 static void delete_from_jump_chain PROTO((rtx));
124 static int delete_labelref_insn PROTO((rtx, rtx, int));
125 static void mark_modified_reg PROTO((rtx, rtx, void *));
126 static void redirect_tablejump PROTO((rtx, rtx));
127 static void jump_optimize_1 PROTO ((rtx, int, int, int, int));
128 #if ! defined(HAVE_cc0) && ! defined(HAVE_conditional_arithmetic)
129 static rtx find_insert_position PROTO((rtx, rtx));
130 #endif
131 static int returnjump_p_1 PROTO((rtx *, void *));
132 static void delete_prior_computation PROTO((rtx, rtx));
133
134 /* Main external entry point into the jump optimizer. See comments before
135 jump_optimize_1 for descriptions of the arguments. */
136 void
137 jump_optimize (f, cross_jump, noop_moves, after_regscan)
138 rtx f;
139 int cross_jump;
140 int noop_moves;
141 int after_regscan;
142 {
143 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0);
144 }
145
146 /* Alternate entry into the jump optimizer. This entry point only rebuilds
147 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
148 instructions. */
149 void
150 rebuild_jump_labels (f)
151 rtx f;
152 {
153 jump_optimize_1 (f, 0, 0, 0, 1);
154 }
155
156 \f
157 /* Delete no-op jumps and optimize jumps to jumps
158 and jumps around jumps.
159 Delete unused labels and unreachable code.
160
161 If CROSS_JUMP is 1, detect matching code
162 before a jump and its destination and unify them.
163 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
164
165 If NOOP_MOVES is nonzero, delete no-op move insns.
166
167 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
168 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
169
170 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
171 and JUMP_LABEL field for jumping insns.
172
173 If `optimize' is zero, don't change any code,
174 just determine whether control drops off the end of the function.
175 This case occurs when we have -W and not -O.
176 It works because `delete_insn' checks the value of `optimize'
177 and refrains from actually deleting when that is 0. */
178
179 static void
180 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, mark_labels_only)
181 rtx f;
182 int cross_jump;
183 int noop_moves;
184 int after_regscan;
185 int mark_labels_only;
186 {
187 register rtx insn, next;
188 int changed;
189 int old_max_reg;
190 int first = 1;
191 int max_uid = 0;
192 rtx last_insn;
193
194 cross_jump_death_matters = (cross_jump == 2);
195 max_uid = init_label_info (f) + 1;
196
197 /* If we are performing cross jump optimizations, then initialize
198 tables mapping UIDs to EH regions to avoid incorrect movement
199 of insns from one EH region to another. */
200 if (flag_exceptions && cross_jump)
201 init_insn_eh_region (f, max_uid);
202
203 delete_barrier_successors (f);
204
205 /* Leave some extra room for labels and duplicate exit test insns
206 we make. */
207 max_jump_chain = max_uid * 14 / 10;
208 jump_chain = (rtx *) xcalloc (max_jump_chain, sizeof (rtx));
209
210 mark_all_labels (f, cross_jump);
211
212 /* Keep track of labels used from static data;
213 they cannot ever be deleted. */
214
215 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
216 LABEL_NUSES (XEXP (insn, 0))++;
217
218 check_exception_handler_labels ();
219
220 /* Keep track of labels used for marking handlers for exception
221 regions; they cannot usually be deleted. */
222
223 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
224 LABEL_NUSES (XEXP (insn, 0))++;
225
226 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
227 notes and recompute LABEL_NUSES. */
228 if (mark_labels_only)
229 goto end;
230
231 exception_optimize ();
232
233 last_insn = delete_unreferenced_labels (f);
234
235 if (optimize == 0)
236 {
237 /* CAN_REACH_END is persistent for each function. Once set it should
238 not be cleared. This is especially true for the case where we
239 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
240 the front-end before compiling each function. */
241 if (calculate_can_reach_end (last_insn, 1, 0))
242 can_reach_end = 1;
243
244 /* Zero the "deleted" flag of all the "deleted" insns. */
245 for (insn = f; insn; insn = NEXT_INSN (insn))
246 INSN_DELETED_P (insn) = 0;
247
248 goto end;
249 }
250
251 #ifdef HAVE_return
252 if (HAVE_return)
253 {
254 /* If we fall through to the epilogue, see if we can insert a RETURN insn
255 in front of it. If the machine allows it at this point (we might be
256 after reload for a leaf routine), it will improve optimization for it
257 to be there. */
258 insn = get_last_insn ();
259 while (insn && GET_CODE (insn) == NOTE)
260 insn = PREV_INSN (insn);
261
262 if (insn && GET_CODE (insn) != BARRIER)
263 {
264 emit_jump_insn (gen_return ());
265 emit_barrier ();
266 }
267 }
268 #endif
269
270 if (noop_moves)
271 delete_noop_moves (f);
272
273 /* If we haven't yet gotten to reload and we have just run regscan,
274 delete any insn that sets a register that isn't used elsewhere.
275 This helps some of the optimizations below by having less insns
276 being jumped around. */
277
278 if (! reload_completed && after_regscan)
279 for (insn = f; insn; insn = next)
280 {
281 rtx set = single_set (insn);
282
283 next = NEXT_INSN (insn);
284
285 if (set && GET_CODE (SET_DEST (set)) == REG
286 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
287 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
288 /* We use regno_last_note_uid so as not to delete the setting
289 of a reg that's used in notes. A subsequent optimization
290 might arrange to use that reg for real. */
291 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
292 && ! side_effects_p (SET_SRC (set))
293 && ! find_reg_note (insn, REG_RETVAL, 0)
294 /* An ADDRESSOF expression can turn into a use of the internal arg
295 pointer, so do not delete the initialization of the internal
296 arg pointer yet. If it is truly dead, flow will delete the
297 initializing insn. */
298 && SET_DEST (set) != current_function_internal_arg_pointer)
299 delete_insn (insn);
300 }
301
302 /* Now iterate optimizing jumps until nothing changes over one pass. */
303 changed = 1;
304 old_max_reg = max_reg_num ();
305 while (changed)
306 {
307 changed = 0;
308
309 for (insn = f; insn; insn = next)
310 {
311 rtx reallabelprev;
312 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
313 rtx nlabel;
314 int this_is_simplejump, this_is_condjump, reversep = 0;
315 int this_is_condjump_in_parallel;
316
317 next = NEXT_INSN (insn);
318
319 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
320 jump. Try to optimize by duplicating the loop exit test if so.
321 This is only safe immediately after regscan, because it uses
322 the values of regno_first_uid and regno_last_uid. */
323 if (after_regscan && GET_CODE (insn) == NOTE
324 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
325 && (temp1 = next_nonnote_insn (insn)) != 0
326 && simplejump_p (temp1))
327 {
328 temp = PREV_INSN (insn);
329 if (duplicate_loop_exit_test (insn))
330 {
331 changed = 1;
332 next = NEXT_INSN (temp);
333 continue;
334 }
335 }
336
337 if (GET_CODE (insn) != JUMP_INSN)
338 continue;
339
340 this_is_simplejump = simplejump_p (insn);
341 this_is_condjump = condjump_p (insn);
342 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
343
344 /* Tension the labels in dispatch tables. */
345
346 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
347 changed |= tension_vector_labels (PATTERN (insn), 0);
348 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
349 changed |= tension_vector_labels (PATTERN (insn), 1);
350
351 /* See if this jump goes to another jump and redirect if so. */
352 nlabel = follow_jumps (JUMP_LABEL (insn));
353 if (nlabel != JUMP_LABEL (insn))
354 changed |= redirect_jump (insn, nlabel);
355
356 /* If a dispatch table always goes to the same place,
357 get rid of it and replace the insn that uses it. */
358
359 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
360 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
361 {
362 int i;
363 rtx pat = PATTERN (insn);
364 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
365 int len = XVECLEN (pat, diff_vec_p);
366 rtx dispatch = prev_real_insn (insn);
367 rtx set;
368
369 for (i = 0; i < len; i++)
370 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
371 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
372 break;
373
374 if (i == len
375 && dispatch != 0
376 && GET_CODE (dispatch) == JUMP_INSN
377 && JUMP_LABEL (dispatch) != 0
378 /* Don't mess with a casesi insn.
379 XXX according to the comment before computed_jump_p(),
380 all casesi insns should be a parallel of the jump
381 and a USE of a LABEL_REF. */
382 && ! ((set = single_set (dispatch)) != NULL
383 && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE))
384 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
385 {
386 redirect_tablejump (dispatch,
387 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
388 changed = 1;
389 }
390 }
391
392 /* If a jump references the end of the function, try to turn
393 it into a RETURN insn, possibly a conditional one. */
394 if (JUMP_LABEL (insn) != 0
395 && (next_active_insn (JUMP_LABEL (insn)) == 0
396 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
397 == RETURN))
398 changed |= redirect_jump (insn, NULL_RTX);
399
400 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
401
402 /* Detect jump to following insn. */
403 if (reallabelprev == insn && this_is_condjump)
404 {
405 next = next_real_insn (JUMP_LABEL (insn));
406 delete_jump (insn);
407 changed = 1;
408 continue;
409 }
410
411 /* Detect a conditional jump going to the same place
412 as an immediately following unconditional jump. */
413 else if (this_is_condjump
414 && (temp = next_active_insn (insn)) != 0
415 && simplejump_p (temp)
416 && (next_active_insn (JUMP_LABEL (insn))
417 == next_active_insn (JUMP_LABEL (temp))))
418 {
419 /* Don't mess up test coverage analysis. */
420 temp2 = temp;
421 if (flag_test_coverage && !reload_completed)
422 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
423 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
424 break;
425
426 if (temp2 == temp)
427 {
428 delete_jump (insn);
429 changed = 1;
430 continue;
431 }
432 }
433
434 /* Detect a conditional jump jumping over an unconditional jump. */
435
436 else if ((this_is_condjump || this_is_condjump_in_parallel)
437 && ! this_is_simplejump
438 && reallabelprev != 0
439 && GET_CODE (reallabelprev) == JUMP_INSN
440 && prev_active_insn (reallabelprev) == insn
441 && no_labels_between_p (insn, reallabelprev)
442 && simplejump_p (reallabelprev))
443 {
444 /* When we invert the unconditional jump, we will be
445 decrementing the usage count of its old label.
446 Make sure that we don't delete it now because that
447 might cause the following code to be deleted. */
448 rtx prev_uses = prev_nonnote_insn (reallabelprev);
449 rtx prev_label = JUMP_LABEL (insn);
450
451 if (prev_label)
452 ++LABEL_NUSES (prev_label);
453
454 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
455 {
456 /* It is very likely that if there are USE insns before
457 this jump, they hold REG_DEAD notes. These REG_DEAD
458 notes are no longer valid due to this optimization,
459 and will cause the life-analysis that following passes
460 (notably delayed-branch scheduling) to think that
461 these registers are dead when they are not.
462
463 To prevent this trouble, we just remove the USE insns
464 from the insn chain. */
465
466 while (prev_uses && GET_CODE (prev_uses) == INSN
467 && GET_CODE (PATTERN (prev_uses)) == USE)
468 {
469 rtx useless = prev_uses;
470 prev_uses = prev_nonnote_insn (prev_uses);
471 delete_insn (useless);
472 }
473
474 delete_insn (reallabelprev);
475 changed = 1;
476 }
477
478 /* We can now safely delete the label if it is unreferenced
479 since the delete_insn above has deleted the BARRIER. */
480 if (prev_label && --LABEL_NUSES (prev_label) == 0)
481 delete_insn (prev_label);
482
483 next = NEXT_INSN (insn);
484 }
485
486 /* If we have an unconditional jump preceded by a USE, try to put
487 the USE before the target and jump there. This simplifies many
488 of the optimizations below since we don't have to worry about
489 dealing with these USE insns. We only do this if the label
490 being branch to already has the identical USE or if code
491 never falls through to that label. */
492
493 else if (this_is_simplejump
494 && (temp = prev_nonnote_insn (insn)) != 0
495 && GET_CODE (temp) == INSN
496 && GET_CODE (PATTERN (temp)) == USE
497 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
498 && (GET_CODE (temp1) == BARRIER
499 || (GET_CODE (temp1) == INSN
500 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
501 /* Don't do this optimization if we have a loop containing
502 only the USE instruction, and the loop start label has
503 a usage count of 1. This is because we will redo this
504 optimization everytime through the outer loop, and jump
505 opt will never exit. */
506 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
507 && temp2 == JUMP_LABEL (insn)
508 && LABEL_NUSES (temp2) == 1))
509 {
510 if (GET_CODE (temp1) == BARRIER)
511 {
512 emit_insn_after (PATTERN (temp), temp1);
513 temp1 = NEXT_INSN (temp1);
514 }
515
516 delete_insn (temp);
517 redirect_jump (insn, get_label_before (temp1));
518 reallabelprev = prev_real_insn (temp1);
519 changed = 1;
520 next = NEXT_INSN (insn);
521 }
522
523 /* Simplify if (...) x = a; else x = b; by converting it
524 to x = b; if (...) x = a;
525 if B is sufficiently simple, the test doesn't involve X,
526 and nothing in the test modifies B or X.
527
528 If we have small register classes, we also can't do this if X
529 is a hard register.
530
531 If the "x = b;" insn has any REG_NOTES, we don't do this because
532 of the possibility that we are running after CSE and there is a
533 REG_EQUAL note that is only valid if the branch has already been
534 taken. If we move the insn with the REG_EQUAL note, we may
535 fold the comparison to always be false in a later CSE pass.
536 (We could also delete the REG_NOTES when moving the insn, but it
537 seems simpler to not move it.) An exception is that we can move
538 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
539 value is the same as "b".
540
541 INSN is the branch over the `else' part.
542
543 We set:
544
545 TEMP to the jump insn preceding "x = a;"
546 TEMP1 to X
547 TEMP2 to the insn that sets "x = b;"
548 TEMP3 to the insn that sets "x = a;"
549 TEMP4 to the set of "x = b"; */
550
551 if (this_is_simplejump
552 && (temp3 = prev_active_insn (insn)) != 0
553 && GET_CODE (temp3) == INSN
554 && (temp4 = single_set (temp3)) != 0
555 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
556 && (! SMALL_REGISTER_CLASSES
557 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
558 && (temp2 = next_active_insn (insn)) != 0
559 && GET_CODE (temp2) == INSN
560 && (temp4 = single_set (temp2)) != 0
561 && rtx_equal_p (SET_DEST (temp4), temp1)
562 && ! side_effects_p (SET_SRC (temp4))
563 && ! may_trap_p (SET_SRC (temp4))
564 && (REG_NOTES (temp2) == 0
565 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
566 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
567 && XEXP (REG_NOTES (temp2), 1) == 0
568 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
569 SET_SRC (temp4))))
570 && (temp = prev_active_insn (temp3)) != 0
571 && condjump_p (temp) && ! simplejump_p (temp)
572 /* TEMP must skip over the "x = a;" insn */
573 && prev_real_insn (JUMP_LABEL (temp)) == insn
574 && no_labels_between_p (insn, JUMP_LABEL (temp))
575 /* There must be no other entries to the "x = b;" insn. */
576 && no_labels_between_p (JUMP_LABEL (temp), temp2)
577 /* INSN must either branch to the insn after TEMP2 or the insn
578 after TEMP2 must branch to the same place as INSN. */
579 && (reallabelprev == temp2
580 || ((temp5 = next_active_insn (temp2)) != 0
581 && simplejump_p (temp5)
582 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
583 {
584 /* The test expression, X, may be a complicated test with
585 multiple branches. See if we can find all the uses of
586 the label that TEMP branches to without hitting a CALL_INSN
587 or a jump to somewhere else. */
588 rtx target = JUMP_LABEL (temp);
589 int nuses = LABEL_NUSES (target);
590 rtx p;
591 #ifdef HAVE_cc0
592 rtx q;
593 #endif
594
595 /* Set P to the first jump insn that goes around "x = a;". */
596 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
597 {
598 if (GET_CODE (p) == JUMP_INSN)
599 {
600 if (condjump_p (p) && ! simplejump_p (p)
601 && JUMP_LABEL (p) == target)
602 {
603 nuses--;
604 if (nuses == 0)
605 break;
606 }
607 else
608 break;
609 }
610 else if (GET_CODE (p) == CALL_INSN)
611 break;
612 }
613
614 #ifdef HAVE_cc0
615 /* We cannot insert anything between a set of cc and its use
616 so if P uses cc0, we must back up to the previous insn. */
617 q = prev_nonnote_insn (p);
618 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
619 && sets_cc0_p (PATTERN (q)))
620 p = q;
621 #endif
622
623 if (p)
624 p = PREV_INSN (p);
625
626 /* If we found all the uses and there was no data conflict, we
627 can move the assignment unless we can branch into the middle
628 from somewhere. */
629 if (nuses == 0 && p
630 && no_labels_between_p (p, insn)
631 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
632 && ! reg_set_between_p (temp1, p, temp3)
633 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
634 || ! modified_between_p (SET_SRC (temp4), p, temp2))
635 /* Verify that registers used by the jump are not clobbered
636 by the instruction being moved. */
637 && ! regs_set_between_p (PATTERN (temp),
638 PREV_INSN (temp2),
639 NEXT_INSN (temp2)))
640 {
641 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
642 delete_insn (temp2);
643
644 /* Set NEXT to an insn that we know won't go away. */
645 next = next_active_insn (insn);
646
647 /* Delete the jump around the set. Note that we must do
648 this before we redirect the test jumps so that it won't
649 delete the code immediately following the assignment
650 we moved (which might be a jump). */
651
652 delete_insn (insn);
653
654 /* We either have two consecutive labels or a jump to
655 a jump, so adjust all the JUMP_INSNs to branch to where
656 INSN branches to. */
657 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
658 if (GET_CODE (p) == JUMP_INSN)
659 redirect_jump (p, target);
660
661 changed = 1;
662 next = NEXT_INSN (insn);
663 continue;
664 }
665 }
666
667 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
668 to x = a; if (...) goto l; x = b;
669 if A is sufficiently simple, the test doesn't involve X,
670 and nothing in the test modifies A or X.
671
672 If we have small register classes, we also can't do this if X
673 is a hard register.
674
675 If the "x = a;" insn has any REG_NOTES, we don't do this because
676 of the possibility that we are running after CSE and there is a
677 REG_EQUAL note that is only valid if the branch has already been
678 taken. If we move the insn with the REG_EQUAL note, we may
679 fold the comparison to always be false in a later CSE pass.
680 (We could also delete the REG_NOTES when moving the insn, but it
681 seems simpler to not move it.) An exception is that we can move
682 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
683 value is the same as "a".
684
685 INSN is the goto.
686
687 We set:
688
689 TEMP to the jump insn preceding "x = a;"
690 TEMP1 to X
691 TEMP2 to the insn that sets "x = b;"
692 TEMP3 to the insn that sets "x = a;"
693 TEMP4 to the set of "x = a"; */
694
695 if (this_is_simplejump
696 && (temp2 = next_active_insn (insn)) != 0
697 && GET_CODE (temp2) == INSN
698 && (temp4 = single_set (temp2)) != 0
699 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
700 && (! SMALL_REGISTER_CLASSES
701 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
702 && (temp3 = prev_active_insn (insn)) != 0
703 && GET_CODE (temp3) == INSN
704 && (temp4 = single_set (temp3)) != 0
705 && rtx_equal_p (SET_DEST (temp4), temp1)
706 && ! side_effects_p (SET_SRC (temp4))
707 && ! may_trap_p (SET_SRC (temp4))
708 && (REG_NOTES (temp3) == 0
709 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
710 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
711 && XEXP (REG_NOTES (temp3), 1) == 0
712 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
713 SET_SRC (temp4))))
714 && (temp = prev_active_insn (temp3)) != 0
715 && condjump_p (temp) && ! simplejump_p (temp)
716 /* TEMP must skip over the "x = a;" insn */
717 && prev_real_insn (JUMP_LABEL (temp)) == insn
718 && no_labels_between_p (temp, insn))
719 {
720 rtx prev_label = JUMP_LABEL (temp);
721 rtx insert_after = prev_nonnote_insn (temp);
722
723 #ifdef HAVE_cc0
724 /* We cannot insert anything between a set of cc and its use. */
725 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
726 && sets_cc0_p (PATTERN (insert_after)))
727 insert_after = prev_nonnote_insn (insert_after);
728 #endif
729 ++LABEL_NUSES (prev_label);
730
731 if (insert_after
732 && no_labels_between_p (insert_after, temp)
733 && ! reg_referenced_between_p (temp1, insert_after, temp3)
734 && ! reg_referenced_between_p (temp1, temp3,
735 NEXT_INSN (temp2))
736 && ! reg_set_between_p (temp1, insert_after, temp)
737 && ! modified_between_p (SET_SRC (temp4), insert_after, temp)
738 /* Verify that registers used by the jump are not clobbered
739 by the instruction being moved. */
740 && ! regs_set_between_p (PATTERN (temp),
741 PREV_INSN (temp3),
742 NEXT_INSN (temp3))
743 && invert_jump (temp, JUMP_LABEL (insn)))
744 {
745 emit_insn_after_with_line_notes (PATTERN (temp3),
746 insert_after, temp3);
747 delete_insn (temp3);
748 delete_insn (insn);
749 /* Set NEXT to an insn that we know won't go away. */
750 next = temp2;
751 changed = 1;
752 }
753 if (prev_label && --LABEL_NUSES (prev_label) == 0)
754 delete_insn (prev_label);
755 if (changed)
756 continue;
757 }
758
759 #if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
760
761 /* If we have if (...) x = exp; and branches are expensive,
762 EXP is a single insn, does not have any side effects, cannot
763 trap, and is not too costly, convert this to
764 t = exp; if (...) x = t;
765
766 Don't do this when we have CC0 because it is unlikely to help
767 and we'd need to worry about where to place the new insn and
768 the potential for conflicts. We also can't do this when we have
769 notes on the insn for the same reason as above.
770
771 If we have conditional arithmetic, this will make this
772 harder to optimize later and isn't needed, so don't do it
773 in that case either.
774
775 We set:
776
777 TEMP to the "x = exp;" insn.
778 TEMP1 to the single set in the "x = exp;" insn.
779 TEMP2 to "x". */
780
781 if (! reload_completed
782 && this_is_condjump && ! this_is_simplejump
783 && BRANCH_COST >= 3
784 && (temp = next_nonnote_insn (insn)) != 0
785 && GET_CODE (temp) == INSN
786 && REG_NOTES (temp) == 0
787 && (reallabelprev == temp
788 || ((temp2 = next_active_insn (temp)) != 0
789 && simplejump_p (temp2)
790 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
791 && (temp1 = single_set (temp)) != 0
792 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
793 && (! SMALL_REGISTER_CLASSES
794 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
795 && GET_CODE (SET_SRC (temp1)) != REG
796 && GET_CODE (SET_SRC (temp1)) != SUBREG
797 && GET_CODE (SET_SRC (temp1)) != CONST_INT
798 && ! side_effects_p (SET_SRC (temp1))
799 && ! may_trap_p (SET_SRC (temp1))
800 && rtx_cost (SET_SRC (temp1), SET) < 10)
801 {
802 rtx new = gen_reg_rtx (GET_MODE (temp2));
803
804 if ((temp3 = find_insert_position (insn, temp))
805 && validate_change (temp, &SET_DEST (temp1), new, 0))
806 {
807 next = emit_insn_after (gen_move_insn (temp2, new), insn);
808 emit_insn_after_with_line_notes (PATTERN (temp),
809 PREV_INSN (temp3), temp);
810 delete_insn (temp);
811 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
812
813 if (after_regscan)
814 {
815 reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
816 old_max_reg = max_reg_num ();
817 }
818 }
819 }
820
821 /* Similarly, if it takes two insns to compute EXP but they
822 have the same destination. Here TEMP3 will be the second
823 insn and TEMP4 the SET from that insn. */
824
825 if (! reload_completed
826 && this_is_condjump && ! this_is_simplejump
827 && BRANCH_COST >= 4
828 && (temp = next_nonnote_insn (insn)) != 0
829 && GET_CODE (temp) == INSN
830 && REG_NOTES (temp) == 0
831 && (temp3 = next_nonnote_insn (temp)) != 0
832 && GET_CODE (temp3) == INSN
833 && REG_NOTES (temp3) == 0
834 && (reallabelprev == temp3
835 || ((temp2 = next_active_insn (temp3)) != 0
836 && simplejump_p (temp2)
837 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
838 && (temp1 = single_set (temp)) != 0
839 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
840 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
841 && (! SMALL_REGISTER_CLASSES
842 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
843 && ! side_effects_p (SET_SRC (temp1))
844 && ! may_trap_p (SET_SRC (temp1))
845 && rtx_cost (SET_SRC (temp1), SET) < 10
846 && (temp4 = single_set (temp3)) != 0
847 && rtx_equal_p (SET_DEST (temp4), temp2)
848 && ! side_effects_p (SET_SRC (temp4))
849 && ! may_trap_p (SET_SRC (temp4))
850 && rtx_cost (SET_SRC (temp4), SET) < 10)
851 {
852 rtx new = gen_reg_rtx (GET_MODE (temp2));
853
854 if ((temp5 = find_insert_position (insn, temp))
855 && (temp6 = find_insert_position (insn, temp3))
856 && validate_change (temp, &SET_DEST (temp1), new, 0))
857 {
858 /* Use the earliest of temp5 and temp6. */
859 if (temp5 != insn)
860 temp6 = temp5;
861 next = emit_insn_after (gen_move_insn (temp2, new), insn);
862 emit_insn_after_with_line_notes (PATTERN (temp),
863 PREV_INSN (temp6), temp);
864 emit_insn_after_with_line_notes
865 (replace_rtx (PATTERN (temp3), temp2, new),
866 PREV_INSN (temp6), temp3);
867 delete_insn (temp);
868 delete_insn (temp3);
869 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
870
871 if (after_regscan)
872 {
873 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
874 old_max_reg = max_reg_num ();
875 }
876 }
877 }
878
879 /* Finally, handle the case where two insns are used to
880 compute EXP but a temporary register is used. Here we must
881 ensure that the temporary register is not used anywhere else. */
882
883 if (! reload_completed
884 && after_regscan
885 && this_is_condjump && ! this_is_simplejump
886 && BRANCH_COST >= 4
887 && (temp = next_nonnote_insn (insn)) != 0
888 && GET_CODE (temp) == INSN
889 && REG_NOTES (temp) == 0
890 && (temp3 = next_nonnote_insn (temp)) != 0
891 && GET_CODE (temp3) == INSN
892 && REG_NOTES (temp3) == 0
893 && (reallabelprev == temp3
894 || ((temp2 = next_active_insn (temp3)) != 0
895 && simplejump_p (temp2)
896 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
897 && (temp1 = single_set (temp)) != 0
898 && (temp5 = SET_DEST (temp1),
899 (GET_CODE (temp5) == REG
900 || (GET_CODE (temp5) == SUBREG
901 && (temp5 = SUBREG_REG (temp5),
902 GET_CODE (temp5) == REG))))
903 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
904 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
905 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
906 && ! side_effects_p (SET_SRC (temp1))
907 && ! may_trap_p (SET_SRC (temp1))
908 && rtx_cost (SET_SRC (temp1), SET) < 10
909 && (temp4 = single_set (temp3)) != 0
910 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
911 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
912 && (! SMALL_REGISTER_CLASSES
913 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
914 && rtx_equal_p (SET_DEST (temp4), temp2)
915 && ! side_effects_p (SET_SRC (temp4))
916 && ! may_trap_p (SET_SRC (temp4))
917 && rtx_cost (SET_SRC (temp4), SET) < 10)
918 {
919 rtx new = gen_reg_rtx (GET_MODE (temp2));
920
921 if ((temp5 = find_insert_position (insn, temp))
922 && (temp6 = find_insert_position (insn, temp3))
923 && validate_change (temp3, &SET_DEST (temp4), new, 0))
924 {
925 /* Use the earliest of temp5 and temp6. */
926 if (temp5 != insn)
927 temp6 = temp5;
928 next = emit_insn_after (gen_move_insn (temp2, new), insn);
929 emit_insn_after_with_line_notes (PATTERN (temp),
930 PREV_INSN (temp6), temp);
931 emit_insn_after_with_line_notes (PATTERN (temp3),
932 PREV_INSN (temp6), temp3);
933 delete_insn (temp);
934 delete_insn (temp3);
935 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
936
937 if (after_regscan)
938 {
939 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
940 old_max_reg = max_reg_num ();
941 }
942 }
943 }
944 #endif /* HAVE_cc0 */
945
946 #ifdef HAVE_conditional_arithmetic
947 /* ??? This is disabled in genconfig, as this simple-minded
948 transformation can incredibly lengthen register lifetimes.
949
950 Consider this example from cexp.c's yyparse:
951
952 234 (set (pc)
953 (if_then_else (ne (reg:DI 149) (const_int 0 [0x0]))
954 (label_ref 248) (pc)))
955 237 (set (reg/i:DI 0 $0) (const_int 1 [0x1]))
956 239 (set (pc) (label_ref 2382))
957 248 (code_label ("yybackup"))
958
959 This will be transformed to:
960
961 237 (set (reg/i:DI 0 $0)
962 (if_then_else:DI (eq (reg:DI 149) (const_int 0 [0x0]))
963 (const_int 1 [0x1]) (reg/i:DI 0 $0)))
964 239 (set (pc)
965 (if_then_else (eq (reg:DI 149) (const_int 0 [0x0]))
966 (label_ref 2382) (pc)))
967
968 which, from this narrow viewpoint looks fine. Except that
969 between this and 3 other ocurrences of the same pattern, $0
970 is now live for basically the entire function, and we'll
971 get an abort in caller_save.
972
973 Any replacement for this code should recall that a set of
974 a register that is not live need not, and indeed should not,
975 be conditionalized. Either that, or delay the transformation
976 until after register allocation. */
977
978 /* See if this is a conditional jump around a small number of
979 instructions that we can conditionalize. Don't do this before
980 the initial CSE pass or after reload.
981
982 We reject any insns that have side effects or may trap.
983 Strictly speaking, this is not needed since the machine may
984 support conditionalizing these too, but we won't deal with that
985 now. Specifically, this means that we can't conditionalize a
986 CALL_INSN, which some machines, such as the ARC, can do, but
987 this is a very minor optimization. */
988 if (this_is_condjump && ! this_is_simplejump
989 && cse_not_expected && optimize > 0 && ! reload_completed
990 && BRANCH_COST > 2
991 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (insn)), 0),
992 insn))
993 {
994 rtx ourcond = XEXP (SET_SRC (PATTERN (insn)), 0);
995 int num_insns = 0;
996 char *storage = (char *) oballoc (0);
997 int last_insn = 0, failed = 0;
998 rtx changed_jump = 0;
999
1000 ourcond = gen_rtx (reverse_condition (GET_CODE (ourcond)),
1001 VOIDmode, XEXP (ourcond, 0),
1002 XEXP (ourcond, 1));
1003
1004 /* Scan forward BRANCH_COST real insns looking for the JUMP_LABEL
1005 of this insn. We see if we think we can conditionalize the
1006 insns we pass. For now, we only deal with insns that have
1007 one SET. We stop after an insn that modifies anything in
1008 OURCOND, if we have too many insns, or if we have an insn
1009 with a side effect or that may trip. Note that we will
1010 be modifying any unconditional jumps we encounter to be
1011 conditional; this will have the effect of also doing this
1012 optimization on the "else" the next time around. */
1013 for (temp1 = NEXT_INSN (insn);
1014 num_insns <= BRANCH_COST && ! failed && temp1 != 0
1015 && GET_CODE (temp1) != CODE_LABEL;
1016 temp1 = NEXT_INSN (temp1))
1017 {
1018 /* Ignore everything but an active insn. */
1019 if (GET_RTX_CLASS (GET_CODE (temp1)) != 'i'
1020 || GET_CODE (PATTERN (temp1)) == USE
1021 || GET_CODE (PATTERN (temp1)) == CLOBBER)
1022 continue;
1023
1024 /* If this was an unconditional jump, record it since we'll
1025 need to remove the BARRIER if we succeed. We can only
1026 have one such jump since there must be a label after
1027 the BARRIER and it's either ours, in which case it's the
1028 only one or some other, in which case we'd fail.
1029 Likewise if it's a CALL_INSN followed by a BARRIER. */
1030
1031 if (simplejump_p (temp1)
1032 || (GET_CODE (temp1) == CALL_INSN
1033 && NEXT_INSN (temp1) != 0
1034 && GET_CODE (NEXT_INSN (temp1)) == BARRIER))
1035 {
1036 if (changed_jump == 0)
1037 changed_jump = temp1;
1038 else
1039 changed_jump
1040 = gen_rtx_INSN_LIST (VOIDmode, temp1, changed_jump);
1041 }
1042
1043 /* See if we are allowed another insn and if this insn
1044 if one we think we may be able to handle. */
1045 if (++num_insns > BRANCH_COST
1046 || last_insn
1047 || (((temp2 = single_set (temp1)) == 0
1048 || side_effects_p (SET_SRC (temp2))
1049 || may_trap_p (SET_SRC (temp2)))
1050 && GET_CODE (temp1) != CALL_INSN))
1051 failed = 1;
1052 else if (temp2 != 0)
1053 validate_change (temp1, &SET_SRC (temp2),
1054 gen_rtx_IF_THEN_ELSE
1055 (GET_MODE (SET_DEST (temp2)),
1056 copy_rtx (ourcond),
1057 SET_SRC (temp2), SET_DEST (temp2)),
1058 1);
1059 else
1060 {
1061 /* This is a CALL_INSN that doesn't have a SET. */
1062 rtx *call_loc = &PATTERN (temp1);
1063
1064 if (GET_CODE (*call_loc) == PARALLEL)
1065 call_loc = &XVECEXP (*call_loc, 0, 0);
1066
1067 validate_change (temp1, call_loc,
1068 gen_rtx_IF_THEN_ELSE
1069 (VOIDmode, copy_rtx (ourcond),
1070 *call_loc, const0_rtx),
1071 1);
1072 }
1073
1074
1075 if (modified_in_p (ourcond, temp1))
1076 last_insn = 1;
1077 }
1078
1079 /* If we've reached our jump label, haven't failed, and all
1080 the changes above are valid, we can delete this jump
1081 insn. Also remove a BARRIER after any jump that used
1082 to be unconditional and remove any REG_EQUAL or REG_EQUIV
1083 that might have previously been present on insns we
1084 made conditional. */
1085 if (temp1 == JUMP_LABEL (insn) && ! failed
1086 && apply_change_group ())
1087 {
1088 for (temp1 = NEXT_INSN (insn); temp1 != JUMP_LABEL (insn);
1089 temp1 = NEXT_INSN (temp1))
1090 if (GET_RTX_CLASS (GET_CODE (temp1)) == 'i')
1091 for (temp2 = REG_NOTES (temp1); temp2 != 0;
1092 temp2 = XEXP (temp2, 1))
1093 if (REG_NOTE_KIND (temp2) == REG_EQUAL
1094 || REG_NOTE_KIND (temp2) == REG_EQUIV)
1095 remove_note (temp1, temp2);
1096
1097 if (changed_jump != 0)
1098 {
1099 while (GET_CODE (changed_jump) == INSN_LIST)
1100 {
1101 delete_barrier (NEXT_INSN (XEXP (changed_jump, 0)));
1102 changed_jump = XEXP (changed_jump, 1);
1103 }
1104
1105 delete_barrier (NEXT_INSN (changed_jump));
1106 }
1107
1108 delete_insn (insn);
1109 changed = 1;
1110 continue;
1111 }
1112 else
1113 {
1114 cancel_changes (0);
1115 obfree (storage);
1116 }
1117 }
1118 #endif
1119 /* If branches are expensive, convert
1120 if (foo) bar++; to bar += (foo != 0);
1121 and similarly for "bar--;"
1122
1123 INSN is the conditional branch around the arithmetic. We set:
1124
1125 TEMP is the arithmetic insn.
1126 TEMP1 is the SET doing the arithmetic.
1127 TEMP2 is the operand being incremented or decremented.
1128 TEMP3 to the condition being tested.
1129 TEMP4 to the earliest insn used to find the condition. */
1130
1131 if ((BRANCH_COST >= 2
1132 #ifdef HAVE_incscc
1133 || HAVE_incscc
1134 #endif
1135 #ifdef HAVE_decscc
1136 || HAVE_decscc
1137 #endif
1138 )
1139 && ! reload_completed
1140 && this_is_condjump && ! this_is_simplejump
1141 && (temp = next_nonnote_insn (insn)) != 0
1142 && (temp1 = single_set (temp)) != 0
1143 && (temp2 = SET_DEST (temp1),
1144 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1145 && GET_CODE (SET_SRC (temp1)) == PLUS
1146 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1147 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1148 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1149 && ! side_effects_p (temp2)
1150 && ! may_trap_p (temp2)
1151 /* INSN must either branch to the insn after TEMP or the insn
1152 after TEMP must branch to the same place as INSN. */
1153 && (reallabelprev == temp
1154 || ((temp3 = next_active_insn (temp)) != 0
1155 && simplejump_p (temp3)
1156 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1157 && (temp3 = get_condition (insn, &temp4)) != 0
1158 /* We must be comparing objects whose modes imply the size.
1159 We could handle BLKmode if (1) emit_store_flag could
1160 and (2) we could find the size reliably. */
1161 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1162 && can_reverse_comparison_p (temp3, insn))
1163 {
1164 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1165 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1166
1167 start_sequence ();
1168
1169 /* It must be the case that TEMP2 is not modified in the range
1170 [TEMP4, INSN). The one exception we make is if the insn
1171 before INSN sets TEMP2 to something which is also unchanged
1172 in that range. In that case, we can move the initialization
1173 into our sequence. */
1174
1175 if ((temp5 = prev_active_insn (insn)) != 0
1176 && no_labels_between_p (temp5, insn)
1177 && GET_CODE (temp5) == INSN
1178 && (temp6 = single_set (temp5)) != 0
1179 && rtx_equal_p (temp2, SET_DEST (temp6))
1180 && (CONSTANT_P (SET_SRC (temp6))
1181 || GET_CODE (SET_SRC (temp6)) == REG
1182 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1183 {
1184 emit_insn (PATTERN (temp5));
1185 init_insn = temp5;
1186 init = SET_SRC (temp6);
1187 }
1188
1189 if (CONSTANT_P (init)
1190 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1191 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1192 XEXP (temp3, 0), XEXP (temp3, 1),
1193 VOIDmode,
1194 (code == LTU || code == LEU
1195 || code == GTU || code == GEU), 1);
1196
1197 /* If we can do the store-flag, do the addition or
1198 subtraction. */
1199
1200 if (target)
1201 target = expand_binop (GET_MODE (temp2),
1202 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1203 ? add_optab : sub_optab),
1204 temp2, target, temp2, 0, OPTAB_WIDEN);
1205
1206 if (target != 0)
1207 {
1208 /* Put the result back in temp2 in case it isn't already.
1209 Then replace the jump, possible a CC0-setting insn in
1210 front of the jump, and TEMP, with the sequence we have
1211 made. */
1212
1213 if (target != temp2)
1214 emit_move_insn (temp2, target);
1215
1216 seq = get_insns ();
1217 end_sequence ();
1218
1219 emit_insns_before (seq, temp4);
1220 delete_insn (temp);
1221
1222 if (init_insn)
1223 delete_insn (init_insn);
1224
1225 next = NEXT_INSN (insn);
1226 #ifdef HAVE_cc0
1227 delete_insn (prev_nonnote_insn (insn));
1228 #endif
1229 delete_insn (insn);
1230
1231 if (after_regscan)
1232 {
1233 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1234 old_max_reg = max_reg_num ();
1235 }
1236
1237 changed = 1;
1238 continue;
1239 }
1240 else
1241 end_sequence ();
1242 }
1243
1244 /* Try to use a conditional move (if the target has them), or a
1245 store-flag insn. If the target has conditional arithmetic as
1246 well as conditional move, the above code will have done something.
1247 Note that we prefer the above code since it is more general: the
1248 code below can make changes that require work to undo.
1249
1250 The general case here is:
1251
1252 1) x = a; if (...) x = b; and
1253 2) if (...) x = b;
1254
1255 If the jump would be faster, the machine should not have defined
1256 the movcc or scc insns!. These cases are often made by the
1257 previous optimization.
1258
1259 The second case is treated as x = x; if (...) x = b;.
1260
1261 INSN here is the jump around the store. We set:
1262
1263 TEMP to the "x op= b;" insn.
1264 TEMP1 to X.
1265 TEMP2 to B.
1266 TEMP3 to A (X in the second case).
1267 TEMP4 to the condition being tested.
1268 TEMP5 to the earliest insn used to find the condition.
1269 TEMP6 to the SET of TEMP. */
1270
1271 if (/* We can't do this after reload has completed. */
1272 ! reload_completed
1273 #ifdef HAVE_conditional_arithmetic
1274 /* Defer this until after CSE so the above code gets the
1275 first crack at it. */
1276 && cse_not_expected
1277 #endif
1278 && this_is_condjump && ! this_is_simplejump
1279 /* Set TEMP to the "x = b;" insn. */
1280 && (temp = next_nonnote_insn (insn)) != 0
1281 && GET_CODE (temp) == INSN
1282 && (temp6 = single_set (temp)) != NULL_RTX
1283 && GET_CODE (temp1 = SET_DEST (temp6)) == REG
1284 && (! SMALL_REGISTER_CLASSES
1285 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
1286 && ! side_effects_p (temp2 = SET_SRC (temp6))
1287 && ! may_trap_p (temp2)
1288 /* Allow either form, but prefer the former if both apply.
1289 There is no point in using the old value of TEMP1 if
1290 it is a register, since cse will alias them. It can
1291 lose if the old value were a hard register since CSE
1292 won't replace hard registers. Avoid using TEMP3 if
1293 small register classes and it is a hard register. */
1294 && (((temp3 = reg_set_last (temp1, insn)) != 0
1295 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
1296 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
1297 /* Make the latter case look like x = x; if (...) x = b; */
1298 || (temp3 = temp1, 1))
1299 /* INSN must either branch to the insn after TEMP or the insn
1300 after TEMP must branch to the same place as INSN. */
1301 && (reallabelprev == temp
1302 || ((temp4 = next_active_insn (temp)) != 0
1303 && simplejump_p (temp4)
1304 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1305 && (temp4 = get_condition (insn, &temp5)) != 0
1306 /* We must be comparing objects whose modes imply the size.
1307 We could handle BLKmode if (1) emit_store_flag could
1308 and (2) we could find the size reliably. */
1309 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1310 /* Even if branches are cheap, the store_flag optimization
1311 can win when the operation to be performed can be
1312 expressed directly. */
1313 #ifdef HAVE_cc0
1314 /* If the previous insn sets CC0 and something else, we can't
1315 do this since we are going to delete that insn. */
1316
1317 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1318 && GET_CODE (temp6) == INSN
1319 && (sets_cc0_p (PATTERN (temp6)) == -1
1320 || (sets_cc0_p (PATTERN (temp6)) == 1
1321 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1322 #endif
1323 )
1324 {
1325 #ifdef HAVE_conditional_move
1326 /* First try a conditional move. */
1327 {
1328 enum rtx_code code = GET_CODE (temp4);
1329 rtx var = temp1;
1330 rtx cond0, cond1, aval, bval;
1331 rtx target, new_insn;
1332
1333 /* Copy the compared variables into cond0 and cond1, so that
1334 any side effects performed in or after the old comparison,
1335 will not affect our compare which will come later. */
1336 /* ??? Is it possible to just use the comparison in the jump
1337 insn? After all, we're going to delete it. We'd have
1338 to modify emit_conditional_move to take a comparison rtx
1339 instead or write a new function. */
1340 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1341 /* We want the target to be able to simplify comparisons with
1342 zero (and maybe other constants as well), so don't create
1343 pseudos for them. There's no need to either. */
1344 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1345 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1346 cond1 = XEXP (temp4, 1);
1347 else
1348 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1349
1350 /* Careful about copying these values -- an IOR or what may
1351 need to do other things, like clobber flags. */
1352 /* ??? Assume for the moment that AVAL is ok. */
1353 aval = temp3;
1354
1355 start_sequence ();
1356
1357 /* We're dealing with a single_set insn with no side effects
1358 on SET_SRC. We do need to be reasonably certain that if
1359 we need to force BVAL into a register that we won't
1360 clobber the flags -- general_operand should suffice. */
1361 if (general_operand (temp2, GET_MODE (var)))
1362 bval = temp2;
1363 else
1364 {
1365 bval = gen_reg_rtx (GET_MODE (var));
1366 new_insn = copy_rtx (temp);
1367 temp6 = single_set (new_insn);
1368 SET_DEST (temp6) = bval;
1369 emit_insn (PATTERN (new_insn));
1370 }
1371
1372 target = emit_conditional_move (var, code,
1373 cond0, cond1, VOIDmode,
1374 aval, bval, GET_MODE (var),
1375 (code == LTU || code == GEU
1376 || code == LEU || code == GTU));
1377
1378 if (target)
1379 {
1380 rtx seq1, seq2, last;
1381 int copy_ok;
1382
1383 /* Save the conditional move sequence but don't emit it
1384 yet. On some machines, like the alpha, it is possible
1385 that temp5 == insn, so next generate the sequence that
1386 saves the compared values and then emit both
1387 sequences ensuring seq1 occurs before seq2. */
1388 seq2 = get_insns ();
1389 end_sequence ();
1390
1391 /* "Now that we can't fail..." Famous last words.
1392 Generate the copy insns that preserve the compared
1393 values. */
1394 start_sequence ();
1395 emit_move_insn (cond0, XEXP (temp4, 0));
1396 if (cond1 != XEXP (temp4, 1))
1397 emit_move_insn (cond1, XEXP (temp4, 1));
1398 seq1 = get_insns ();
1399 end_sequence ();
1400
1401 /* Validate the sequence -- this may be some weird
1402 bit-extract-and-test instruction for which there
1403 exists no complimentary bit-extract insn. */
1404 copy_ok = 1;
1405 for (last = seq1; last ; last = NEXT_INSN (last))
1406 if (recog_memoized (last) < 0)
1407 {
1408 copy_ok = 0;
1409 break;
1410 }
1411
1412 if (copy_ok)
1413 {
1414 emit_insns_before (seq1, temp5);
1415
1416 /* Insert conditional move after insn, to be sure
1417 that the jump and a possible compare won't be
1418 separated. */
1419 last = emit_insns_after (seq2, insn);
1420
1421 /* ??? We can also delete the insn that sets X to A.
1422 Flow will do it too though. */
1423 delete_insn (temp);
1424 next = NEXT_INSN (insn);
1425 delete_jump (insn);
1426
1427 if (after_regscan)
1428 {
1429 reg_scan_update (seq1, NEXT_INSN (last),
1430 old_max_reg);
1431 old_max_reg = max_reg_num ();
1432 }
1433
1434 changed = 1;
1435 continue;
1436 }
1437 }
1438 else
1439 end_sequence ();
1440 }
1441 #endif
1442
1443 /* That didn't work, try a store-flag insn.
1444
1445 We further divide the cases into:
1446
1447 1) x = a; if (...) x = b; and either A or B is zero,
1448 2) if (...) x = 0; and jumps are expensive,
1449 3) x = a; if (...) x = b; and A and B are constants where all
1450 the set bits in A are also set in B and jumps are expensive,
1451 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1452 more expensive, and
1453 5) if (...) x = b; if jumps are even more expensive. */
1454
1455 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1456 && ((GET_CODE (temp3) == CONST_INT)
1457 /* Make the latter case look like
1458 x = x; if (...) x = 0; */
1459 || (temp3 = temp1,
1460 ((BRANCH_COST >= 2
1461 && temp2 == const0_rtx)
1462 || BRANCH_COST >= 3)))
1463 /* If B is zero, OK; if A is zero, can only do (1) if we
1464 can reverse the condition. See if (3) applies possibly
1465 by reversing the condition. Prefer reversing to (4) when
1466 branches are very expensive. */
1467 && (((BRANCH_COST >= 2
1468 || STORE_FLAG_VALUE == -1
1469 || (STORE_FLAG_VALUE == 1
1470 /* Check that the mask is a power of two,
1471 so that it can probably be generated
1472 with a shift. */
1473 && GET_CODE (temp3) == CONST_INT
1474 && exact_log2 (INTVAL (temp3)) >= 0))
1475 && (reversep = 0, temp2 == const0_rtx))
1476 || ((BRANCH_COST >= 2
1477 || STORE_FLAG_VALUE == -1
1478 || (STORE_FLAG_VALUE == 1
1479 && GET_CODE (temp2) == CONST_INT
1480 && exact_log2 (INTVAL (temp2)) >= 0))
1481 && temp3 == const0_rtx
1482 && (reversep = can_reverse_comparison_p (temp4, insn)))
1483 || (BRANCH_COST >= 2
1484 && GET_CODE (temp2) == CONST_INT
1485 && GET_CODE (temp3) == CONST_INT
1486 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1487 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1488 && (reversep = can_reverse_comparison_p (temp4,
1489 insn)))))
1490 || BRANCH_COST >= 3)
1491 )
1492 {
1493 enum rtx_code code = GET_CODE (temp4);
1494 rtx uval, cval, var = temp1;
1495 int normalizep;
1496 rtx target;
1497
1498 /* If necessary, reverse the condition. */
1499 if (reversep)
1500 code = reverse_condition (code), uval = temp2, cval = temp3;
1501 else
1502 uval = temp3, cval = temp2;
1503
1504 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1505 is the constant 1, it is best to just compute the result
1506 directly. If UVAL is constant and STORE_FLAG_VALUE
1507 includes all of its bits, it is best to compute the flag
1508 value unnormalized and `and' it with UVAL. Otherwise,
1509 normalize to -1 and `and' with UVAL. */
1510 normalizep = (cval != const0_rtx ? -1
1511 : (uval == const1_rtx ? 1
1512 : (GET_CODE (uval) == CONST_INT
1513 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1514 ? 0 : -1));
1515
1516 /* We will be putting the store-flag insn immediately in
1517 front of the comparison that was originally being done,
1518 so we know all the variables in TEMP4 will be valid.
1519 However, this might be in front of the assignment of
1520 A to VAR. If it is, it would clobber the store-flag
1521 we will be emitting.
1522
1523 Therefore, emit into a temporary which will be copied to
1524 VAR immediately after TEMP. */
1525
1526 start_sequence ();
1527 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1528 XEXP (temp4, 0), XEXP (temp4, 1),
1529 VOIDmode,
1530 (code == LTU || code == LEU
1531 || code == GEU || code == GTU),
1532 normalizep);
1533 if (target)
1534 {
1535 rtx seq;
1536 rtx before = insn;
1537
1538 seq = get_insns ();
1539 end_sequence ();
1540
1541 /* Put the store-flag insns in front of the first insn
1542 used to compute the condition to ensure that we
1543 use the same values of them as the current
1544 comparison. However, the remainder of the insns we
1545 generate will be placed directly in front of the
1546 jump insn, in case any of the pseudos we use
1547 are modified earlier. */
1548
1549 emit_insns_before (seq, temp5);
1550
1551 start_sequence ();
1552
1553 /* Both CVAL and UVAL are non-zero. */
1554 if (cval != const0_rtx && uval != const0_rtx)
1555 {
1556 rtx tem1, tem2;
1557
1558 tem1 = expand_and (uval, target, NULL_RTX);
1559 if (GET_CODE (cval) == CONST_INT
1560 && GET_CODE (uval) == CONST_INT
1561 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1562 tem2 = cval;
1563 else
1564 {
1565 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1566 target, NULL_RTX, 0);
1567 tem2 = expand_and (cval, tem2,
1568 (GET_CODE (tem2) == REG
1569 ? tem2 : 0));
1570 }
1571
1572 /* If we usually make new pseudos, do so here. This
1573 turns out to help machines that have conditional
1574 move insns. */
1575 /* ??? Conditional moves have already been handled.
1576 This may be obsolete. */
1577
1578 if (flag_expensive_optimizations)
1579 target = 0;
1580
1581 target = expand_binop (GET_MODE (var), ior_optab,
1582 tem1, tem2, target,
1583 1, OPTAB_WIDEN);
1584 }
1585 else if (normalizep != 1)
1586 {
1587 /* We know that either CVAL or UVAL is zero. If
1588 UVAL is zero, negate TARGET and `and' with CVAL.
1589 Otherwise, `and' with UVAL. */
1590 if (uval == const0_rtx)
1591 {
1592 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1593 target, NULL_RTX, 0);
1594 uval = cval;
1595 }
1596
1597 target = expand_and (uval, target,
1598 (GET_CODE (target) == REG
1599 && ! preserve_subexpressions_p ()
1600 ? target : NULL_RTX));
1601 }
1602
1603 emit_move_insn (var, target);
1604 seq = get_insns ();
1605 end_sequence ();
1606 #ifdef HAVE_cc0
1607 /* If INSN uses CC0, we must not separate it from the
1608 insn that sets cc0. */
1609 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1610 before = prev_nonnote_insn (before);
1611 #endif
1612 emit_insns_before (seq, before);
1613
1614 delete_insn (temp);
1615 next = NEXT_INSN (insn);
1616 delete_jump (insn);
1617
1618 if (after_regscan)
1619 {
1620 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1621 old_max_reg = max_reg_num ();
1622 }
1623
1624 changed = 1;
1625 continue;
1626 }
1627 else
1628 end_sequence ();
1629 }
1630 }
1631
1632
1633 /* Simplify if (...) x = 1; else {...} if (x) ...
1634 We recognize this case scanning backwards as well.
1635
1636 TEMP is the assignment to x;
1637 TEMP1 is the label at the head of the second if. */
1638 /* ?? This should call get_condition to find the values being
1639 compared, instead of looking for a COMPARE insn when HAVE_cc0
1640 is not defined. This would allow it to work on the m88k. */
1641 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1642 is not defined and the condition is tested by a separate compare
1643 insn. This is because the code below assumes that the result
1644 of the compare dies in the following branch.
1645
1646 Not only that, but there might be other insns between the
1647 compare and branch whose results are live. Those insns need
1648 to be executed.
1649
1650 A way to fix this is to move the insns at JUMP_LABEL (insn)
1651 to before INSN. If we are running before flow, they will
1652 be deleted if they aren't needed. But this doesn't work
1653 well after flow.
1654
1655 This is really a special-case of jump threading, anyway. The
1656 right thing to do is to replace this and jump threading with
1657 much simpler code in cse.
1658
1659 This code has been turned off in the non-cc0 case in the
1660 meantime. */
1661
1662 #ifdef HAVE_cc0
1663 else if (this_is_simplejump
1664 /* Safe to skip USE and CLOBBER insns here
1665 since they will not be deleted. */
1666 && (temp = prev_active_insn (insn))
1667 && no_labels_between_p (temp, insn)
1668 && GET_CODE (temp) == INSN
1669 && GET_CODE (PATTERN (temp)) == SET
1670 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1671 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1672 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1673 /* If we find that the next value tested is `x'
1674 (TEMP1 is the insn where this happens), win. */
1675 && GET_CODE (temp1) == INSN
1676 && GET_CODE (PATTERN (temp1)) == SET
1677 #ifdef HAVE_cc0
1678 /* Does temp1 `tst' the value of x? */
1679 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1680 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1681 && (temp1 = next_nonnote_insn (temp1))
1682 #else
1683 /* Does temp1 compare the value of x against zero? */
1684 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1685 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1686 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1687 == SET_DEST (PATTERN (temp)))
1688 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1689 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1690 #endif
1691 && condjump_p (temp1))
1692 {
1693 /* Get the if_then_else from the condjump. */
1694 rtx choice = SET_SRC (PATTERN (temp1));
1695 if (GET_CODE (choice) == IF_THEN_ELSE)
1696 {
1697 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1698 rtx val = SET_SRC (PATTERN (temp));
1699 rtx cond
1700 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1701 val, const0_rtx);
1702 rtx ultimate;
1703
1704 if (cond == const_true_rtx)
1705 ultimate = XEXP (choice, 1);
1706 else if (cond == const0_rtx)
1707 ultimate = XEXP (choice, 2);
1708 else
1709 ultimate = 0;
1710
1711 if (ultimate == pc_rtx)
1712 ultimate = get_label_after (temp1);
1713 else if (ultimate && GET_CODE (ultimate) != RETURN)
1714 ultimate = XEXP (ultimate, 0);
1715
1716 if (ultimate && JUMP_LABEL(insn) != ultimate)
1717 changed |= redirect_jump (insn, ultimate);
1718 }
1719 }
1720 #endif
1721
1722 #if 0
1723 /* @@ This needs a bit of work before it will be right.
1724
1725 Any type of comparison can be accepted for the first and
1726 second compare. When rewriting the first jump, we must
1727 compute the what conditions can reach label3, and use the
1728 appropriate code. We can not simply reverse/swap the code
1729 of the first jump. In some cases, the second jump must be
1730 rewritten also.
1731
1732 For example,
1733 < == converts to > ==
1734 < != converts to == >
1735 etc.
1736
1737 If the code is written to only accept an '==' test for the second
1738 compare, then all that needs to be done is to swap the condition
1739 of the first branch.
1740
1741 It is questionable whether we want this optimization anyways,
1742 since if the user wrote code like this because he/she knew that
1743 the jump to label1 is taken most of the time, then rewriting
1744 this gives slower code. */
1745 /* @@ This should call get_condition to find the values being
1746 compared, instead of looking for a COMPARE insn when HAVE_cc0
1747 is not defined. This would allow it to work on the m88k. */
1748 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1749 is not defined and the condition is tested by a separate compare
1750 insn. This is because the code below assumes that the result
1751 of the compare dies in the following branch. */
1752
1753 /* Simplify test a ~= b
1754 condjump label1;
1755 test a == b
1756 condjump label2;
1757 jump label3;
1758 label1:
1759
1760 rewriting as
1761 test a ~~= b
1762 condjump label3
1763 test a == b
1764 condjump label2
1765 label1:
1766
1767 where ~= is an inequality, e.g. >, and ~~= is the swapped
1768 inequality, e.g. <.
1769
1770 We recognize this case scanning backwards.
1771
1772 TEMP is the conditional jump to `label2';
1773 TEMP1 is the test for `a == b';
1774 TEMP2 is the conditional jump to `label1';
1775 TEMP3 is the test for `a ~= b'. */
1776 else if (this_is_simplejump
1777 && (temp = prev_active_insn (insn))
1778 && no_labels_between_p (temp, insn)
1779 && condjump_p (temp)
1780 && (temp1 = prev_active_insn (temp))
1781 && no_labels_between_p (temp1, temp)
1782 && GET_CODE (temp1) == INSN
1783 && GET_CODE (PATTERN (temp1)) == SET
1784 #ifdef HAVE_cc0
1785 && sets_cc0_p (PATTERN (temp1)) == 1
1786 #else
1787 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1788 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1789 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1790 #endif
1791 && (temp2 = prev_active_insn (temp1))
1792 && no_labels_between_p (temp2, temp1)
1793 && condjump_p (temp2)
1794 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1795 && (temp3 = prev_active_insn (temp2))
1796 && no_labels_between_p (temp3, temp2)
1797 && GET_CODE (PATTERN (temp3)) == SET
1798 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1799 SET_DEST (PATTERN (temp1)))
1800 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1801 SET_SRC (PATTERN (temp3)))
1802 && ! inequality_comparisons_p (PATTERN (temp))
1803 && inequality_comparisons_p (PATTERN (temp2)))
1804 {
1805 rtx fallthrough_label = JUMP_LABEL (temp2);
1806
1807 ++LABEL_NUSES (fallthrough_label);
1808 if (swap_jump (temp2, JUMP_LABEL (insn)))
1809 {
1810 delete_insn (insn);
1811 changed = 1;
1812 }
1813
1814 if (--LABEL_NUSES (fallthrough_label) == 0)
1815 delete_insn (fallthrough_label);
1816 }
1817 #endif
1818 /* Simplify if (...) {... x = 1;} if (x) ...
1819
1820 We recognize this case backwards.
1821
1822 TEMP is the test of `x';
1823 TEMP1 is the assignment to `x' at the end of the
1824 previous statement. */
1825 /* @@ This should call get_condition to find the values being
1826 compared, instead of looking for a COMPARE insn when HAVE_cc0
1827 is not defined. This would allow it to work on the m88k. */
1828 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1829 is not defined and the condition is tested by a separate compare
1830 insn. This is because the code below assumes that the result
1831 of the compare dies in the following branch. */
1832
1833 /* ??? This has to be turned off. The problem is that the
1834 unconditional jump might indirectly end up branching to the
1835 label between TEMP1 and TEMP. We can't detect this, in general,
1836 since it may become a jump to there after further optimizations.
1837 If that jump is done, it will be deleted, so we will retry
1838 this optimization in the next pass, thus an infinite loop.
1839
1840 The present code prevents this by putting the jump after the
1841 label, but this is not logically correct. */
1842 #if 0
1843 else if (this_is_condjump
1844 /* Safe to skip USE and CLOBBER insns here
1845 since they will not be deleted. */
1846 && (temp = prev_active_insn (insn))
1847 && no_labels_between_p (temp, insn)
1848 && GET_CODE (temp) == INSN
1849 && GET_CODE (PATTERN (temp)) == SET
1850 #ifdef HAVE_cc0
1851 && sets_cc0_p (PATTERN (temp)) == 1
1852 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1853 #else
1854 /* Temp must be a compare insn, we can not accept a register
1855 to register move here, since it may not be simply a
1856 tst insn. */
1857 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1858 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1859 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1860 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1861 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1862 #endif
1863 /* May skip USE or CLOBBER insns here
1864 for checking for opportunity, since we
1865 take care of them later. */
1866 && (temp1 = prev_active_insn (temp))
1867 && GET_CODE (temp1) == INSN
1868 && GET_CODE (PATTERN (temp1)) == SET
1869 #ifdef HAVE_cc0
1870 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1871 #else
1872 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1873 == SET_DEST (PATTERN (temp1)))
1874 #endif
1875 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1876 /* If this isn't true, cse will do the job. */
1877 && ! no_labels_between_p (temp1, temp))
1878 {
1879 /* Get the if_then_else from the condjump. */
1880 rtx choice = SET_SRC (PATTERN (insn));
1881 if (GET_CODE (choice) == IF_THEN_ELSE
1882 && (GET_CODE (XEXP (choice, 0)) == EQ
1883 || GET_CODE (XEXP (choice, 0)) == NE))
1884 {
1885 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1886 rtx last_insn;
1887 rtx ultimate;
1888 rtx p;
1889
1890 /* Get the place that condjump will jump to
1891 if it is reached from here. */
1892 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1893 == want_nonzero)
1894 ultimate = XEXP (choice, 1);
1895 else
1896 ultimate = XEXP (choice, 2);
1897 /* Get it as a CODE_LABEL. */
1898 if (ultimate == pc_rtx)
1899 ultimate = get_label_after (insn);
1900 else
1901 /* Get the label out of the LABEL_REF. */
1902 ultimate = XEXP (ultimate, 0);
1903
1904 /* Insert the jump immediately before TEMP, specifically
1905 after the label that is between TEMP1 and TEMP. */
1906 last_insn = PREV_INSN (temp);
1907
1908 /* If we would be branching to the next insn, the jump
1909 would immediately be deleted and the re-inserted in
1910 a subsequent pass over the code. So don't do anything
1911 in that case. */
1912 if (next_active_insn (last_insn)
1913 != next_active_insn (ultimate))
1914 {
1915 emit_barrier_after (last_insn);
1916 p = emit_jump_insn_after (gen_jump (ultimate),
1917 last_insn);
1918 JUMP_LABEL (p) = ultimate;
1919 ++LABEL_NUSES (ultimate);
1920 if (INSN_UID (ultimate) < max_jump_chain
1921 && INSN_CODE (p) < max_jump_chain)
1922 {
1923 jump_chain[INSN_UID (p)]
1924 = jump_chain[INSN_UID (ultimate)];
1925 jump_chain[INSN_UID (ultimate)] = p;
1926 }
1927 changed = 1;
1928 continue;
1929 }
1930 }
1931 }
1932 #endif
1933 #ifdef HAVE_trap
1934 /* Detect a conditional jump jumping over an unconditional trap. */
1935 else if (HAVE_trap
1936 && this_is_condjump && ! this_is_simplejump
1937 && reallabelprev != 0
1938 && GET_CODE (reallabelprev) == INSN
1939 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
1940 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
1941 && prev_active_insn (reallabelprev) == insn
1942 && no_labels_between_p (insn, reallabelprev)
1943 && (temp2 = get_condition (insn, &temp4))
1944 && can_reverse_comparison_p (temp2, insn))
1945 {
1946 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
1947 XEXP (temp2, 0), XEXP (temp2, 1),
1948 TRAP_CODE (PATTERN (reallabelprev)));
1949
1950 if (new)
1951 {
1952 emit_insn_before (new, temp4);
1953 delete_insn (reallabelprev);
1954 delete_jump (insn);
1955 changed = 1;
1956 continue;
1957 }
1958 }
1959 /* Detect a jump jumping to an unconditional trap. */
1960 else if (HAVE_trap && this_is_condjump
1961 && (temp = next_active_insn (JUMP_LABEL (insn)))
1962 && GET_CODE (temp) == INSN
1963 && GET_CODE (PATTERN (temp)) == TRAP_IF
1964 && (this_is_simplejump
1965 || (temp2 = get_condition (insn, &temp4))))
1966 {
1967 rtx tc = TRAP_CONDITION (PATTERN (temp));
1968
1969 if (tc == const_true_rtx
1970 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
1971 {
1972 rtx new;
1973 /* Replace an unconditional jump to a trap with a trap. */
1974 if (this_is_simplejump)
1975 {
1976 emit_barrier_after (emit_insn_before (gen_trap (), insn));
1977 delete_jump (insn);
1978 changed = 1;
1979 continue;
1980 }
1981 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
1982 XEXP (temp2, 1),
1983 TRAP_CODE (PATTERN (temp)));
1984 if (new)
1985 {
1986 emit_insn_before (new, temp4);
1987 delete_jump (insn);
1988 changed = 1;
1989 continue;
1990 }
1991 }
1992 /* If the trap condition and jump condition are mutually
1993 exclusive, redirect the jump to the following insn. */
1994 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
1995 && ! this_is_simplejump
1996 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
1997 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
1998 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
1999 && redirect_jump (insn, get_label_after (temp)))
2000 {
2001 changed = 1;
2002 continue;
2003 }
2004 }
2005 #endif
2006 else
2007 {
2008 /* Detect a jump to a jump. */
2009
2010 /* Look for if (foo) bar; else break; */
2011 /* The insns look like this:
2012 insn = condjump label1;
2013 ...range1 (some insns)...
2014 jump label2;
2015 label1:
2016 ...range2 (some insns)...
2017 jump somewhere unconditionally
2018 label2: */
2019 {
2020 rtx label1 = next_label (insn);
2021 rtx range1end = label1 ? prev_active_insn (label1) : 0;
2022 /* Don't do this optimization on the first round, so that
2023 jump-around-a-jump gets simplified before we ask here
2024 whether a jump is unconditional.
2025
2026 Also don't do it when we are called after reload since
2027 it will confuse reorg. */
2028 if (! first
2029 && (reload_completed ? ! flag_delayed_branch : 1)
2030 /* Make sure INSN is something we can invert. */
2031 && condjump_p (insn)
2032 && label1 != 0
2033 && JUMP_LABEL (insn) == label1
2034 && LABEL_NUSES (label1) == 1
2035 && GET_CODE (range1end) == JUMP_INSN
2036 && simplejump_p (range1end))
2037 {
2038 rtx label2 = next_label (label1);
2039 rtx range2end = label2 ? prev_active_insn (label2) : 0;
2040 if (range1end != range2end
2041 && JUMP_LABEL (range1end) == label2
2042 && GET_CODE (range2end) == JUMP_INSN
2043 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
2044 /* Invert the jump condition, so we
2045 still execute the same insns in each case. */
2046 && invert_jump (insn, label1))
2047 {
2048 rtx range1beg = next_active_insn (insn);
2049 rtx range2beg = next_active_insn (label1);
2050 rtx range1after, range2after;
2051 rtx range1before, range2before;
2052 rtx rangenext;
2053
2054 /* Include in each range any notes before it, to be
2055 sure that we get the line number note if any, even
2056 if there are other notes here. */
2057 while (PREV_INSN (range1beg)
2058 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
2059 range1beg = PREV_INSN (range1beg);
2060
2061 while (PREV_INSN (range2beg)
2062 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
2063 range2beg = PREV_INSN (range2beg);
2064
2065 /* Don't move NOTEs for blocks or loops; shift them
2066 outside the ranges, where they'll stay put. */
2067 range1beg = squeeze_notes (range1beg, range1end);
2068 range2beg = squeeze_notes (range2beg, range2end);
2069
2070 /* Get current surrounds of the 2 ranges. */
2071 range1before = PREV_INSN (range1beg);
2072 range2before = PREV_INSN (range2beg);
2073 range1after = NEXT_INSN (range1end);
2074 range2after = NEXT_INSN (range2end);
2075
2076 /* Splice range2 where range1 was. */
2077 NEXT_INSN (range1before) = range2beg;
2078 PREV_INSN (range2beg) = range1before;
2079 NEXT_INSN (range2end) = range1after;
2080 PREV_INSN (range1after) = range2end;
2081 /* Splice range1 where range2 was. */
2082 NEXT_INSN (range2before) = range1beg;
2083 PREV_INSN (range1beg) = range2before;
2084 NEXT_INSN (range1end) = range2after;
2085 PREV_INSN (range2after) = range1end;
2086
2087 /* Check for loop notes between the end of
2088 range2, and the next code label. If there is one,
2089 then what we have really seen is
2090 if (foo) break; end_of_loop;
2091 and moved the break sequence outside the loop.
2092 We must move LOOP_END, LOOP_VTOP and LOOP_CONT
2093 notes (in order) to where the loop really ends now,
2094 or we will confuse loop optimization. Stop if we
2095 find a LOOP_BEG note first, since we don't want to
2096 move the notes in that case. */
2097 for (;range2after != label2; range2after = rangenext)
2098 {
2099 rangenext = NEXT_INSN (range2after);
2100 if (GET_CODE (range2after) == NOTE)
2101 {
2102 int kind = NOTE_LINE_NUMBER (range2after);
2103 if (kind == NOTE_INSN_LOOP_END
2104 || kind == NOTE_INSN_LOOP_VTOP
2105 || kind == NOTE_INSN_LOOP_CONT)
2106 {
2107 NEXT_INSN (PREV_INSN (range2after))
2108 = rangenext;
2109 PREV_INSN (rangenext)
2110 = PREV_INSN (range2after);
2111 PREV_INSN (range2after)
2112 = PREV_INSN (range1beg);
2113 NEXT_INSN (range2after) = range1beg;
2114 NEXT_INSN (PREV_INSN (range1beg))
2115 = range2after;
2116 PREV_INSN (range1beg) = range2after;
2117 }
2118 else if (NOTE_LINE_NUMBER (range2after)
2119 == NOTE_INSN_LOOP_BEG)
2120 break;
2121 }
2122 }
2123 changed = 1;
2124 continue;
2125 }
2126 }
2127 }
2128
2129 /* Now that the jump has been tensioned,
2130 try cross jumping: check for identical code
2131 before the jump and before its target label. */
2132
2133 /* First, cross jumping of conditional jumps: */
2134
2135 if (cross_jump && condjump_p (insn))
2136 {
2137 rtx newjpos, newlpos;
2138 rtx x = prev_real_insn (JUMP_LABEL (insn));
2139
2140 /* A conditional jump may be crossjumped
2141 only if the place it jumps to follows
2142 an opposing jump that comes back here. */
2143
2144 if (x != 0 && ! jump_back_p (x, insn))
2145 /* We have no opposing jump;
2146 cannot cross jump this insn. */
2147 x = 0;
2148
2149 newjpos = 0;
2150 /* TARGET is nonzero if it is ok to cross jump
2151 to code before TARGET. If so, see if matches. */
2152 if (x != 0)
2153 find_cross_jump (insn, x, 2,
2154 &newjpos, &newlpos);
2155
2156 if (newjpos != 0)
2157 {
2158 do_cross_jump (insn, newjpos, newlpos);
2159 /* Make the old conditional jump
2160 into an unconditional one. */
2161 SET_SRC (PATTERN (insn))
2162 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
2163 INSN_CODE (insn) = -1;
2164 emit_barrier_after (insn);
2165 /* Add to jump_chain unless this is a new label
2166 whose UID is too large. */
2167 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
2168 {
2169 jump_chain[INSN_UID (insn)]
2170 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2171 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2172 }
2173 changed = 1;
2174 next = insn;
2175 }
2176 }
2177
2178 /* Cross jumping of unconditional jumps:
2179 a few differences. */
2180
2181 if (cross_jump && simplejump_p (insn))
2182 {
2183 rtx newjpos, newlpos;
2184 rtx target;
2185
2186 newjpos = 0;
2187
2188 /* TARGET is nonzero if it is ok to cross jump
2189 to code before TARGET. If so, see if matches. */
2190 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2191 &newjpos, &newlpos);
2192
2193 /* If cannot cross jump to code before the label,
2194 see if we can cross jump to another jump to
2195 the same label. */
2196 /* Try each other jump to this label. */
2197 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2198 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2199 target != 0 && newjpos == 0;
2200 target = jump_chain[INSN_UID (target)])
2201 if (target != insn
2202 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2203 /* Ignore TARGET if it's deleted. */
2204 && ! INSN_DELETED_P (target))
2205 find_cross_jump (insn, target, 2,
2206 &newjpos, &newlpos);
2207
2208 if (newjpos != 0)
2209 {
2210 do_cross_jump (insn, newjpos, newlpos);
2211 changed = 1;
2212 next = insn;
2213 }
2214 }
2215
2216 /* This code was dead in the previous jump.c! */
2217 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2218 {
2219 /* Return insns all "jump to the same place"
2220 so we can cross-jump between any two of them. */
2221
2222 rtx newjpos, newlpos, target;
2223
2224 newjpos = 0;
2225
2226 /* If cannot cross jump to code before the label,
2227 see if we can cross jump to another jump to
2228 the same label. */
2229 /* Try each other jump to this label. */
2230 for (target = jump_chain[0];
2231 target != 0 && newjpos == 0;
2232 target = jump_chain[INSN_UID (target)])
2233 if (target != insn
2234 && ! INSN_DELETED_P (target)
2235 && GET_CODE (PATTERN (target)) == RETURN)
2236 find_cross_jump (insn, target, 2,
2237 &newjpos, &newlpos);
2238
2239 if (newjpos != 0)
2240 {
2241 do_cross_jump (insn, newjpos, newlpos);
2242 changed = 1;
2243 next = insn;
2244 }
2245 }
2246 }
2247 }
2248
2249 first = 0;
2250 }
2251
2252 /* Delete extraneous line number notes.
2253 Note that two consecutive notes for different lines are not really
2254 extraneous. There should be some indication where that line belonged,
2255 even if it became empty. */
2256
2257 {
2258 rtx last_note = 0;
2259
2260 for (insn = f; insn; insn = NEXT_INSN (insn))
2261 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2262 {
2263 /* Delete this note if it is identical to previous note. */
2264 if (last_note
2265 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2266 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2267 {
2268 delete_insn (insn);
2269 continue;
2270 }
2271
2272 last_note = insn;
2273 }
2274 }
2275
2276 #ifdef HAVE_return
2277 if (HAVE_return)
2278 {
2279 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2280 in front of it. If the machine allows it at this point (we might be
2281 after reload for a leaf routine), it will improve optimization for it
2282 to be there. We do this both here and at the start of this pass since
2283 the RETURN might have been deleted by some of our optimizations. */
2284 insn = get_last_insn ();
2285 while (insn && GET_CODE (insn) == NOTE)
2286 insn = PREV_INSN (insn);
2287
2288 if (insn && GET_CODE (insn) != BARRIER)
2289 {
2290 emit_jump_insn (gen_return ());
2291 emit_barrier ();
2292 }
2293 }
2294 #endif
2295
2296 /* CAN_REACH_END is persistent for each function. Once set it should
2297 not be cleared. This is especially true for the case where we
2298 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
2299 the front-end before compiling each function. */
2300 if (calculate_can_reach_end (last_insn, 0, 1))
2301 can_reach_end = 1;
2302
2303 end:
2304 /* Clean up. */
2305 free (jump_chain);
2306 jump_chain = 0;
2307 }
2308 \f
2309 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2310 notes whose labels don't occur in the insn any more. Returns the
2311 largest INSN_UID found. */
2312 static int
2313 init_label_info (f)
2314 rtx f;
2315 {
2316 int largest_uid = 0;
2317 rtx insn;
2318
2319 for (insn = f; insn; insn = NEXT_INSN (insn))
2320 {
2321 if (GET_CODE (insn) == CODE_LABEL)
2322 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
2323 else if (GET_CODE (insn) == JUMP_INSN)
2324 JUMP_LABEL (insn) = 0;
2325 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2326 {
2327 rtx note, next;
2328
2329 for (note = REG_NOTES (insn); note; note = next)
2330 {
2331 next = XEXP (note, 1);
2332 if (REG_NOTE_KIND (note) == REG_LABEL
2333 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
2334 remove_note (insn, note);
2335 }
2336 }
2337 if (INSN_UID (insn) > largest_uid)
2338 largest_uid = INSN_UID (insn);
2339 }
2340
2341 return largest_uid;
2342 }
2343
2344 /* Delete insns following barriers, up to next label.
2345
2346 Also delete no-op jumps created by gcse. */
2347 static void
2348 delete_barrier_successors (f)
2349 rtx f;
2350 {
2351 rtx insn;
2352
2353 for (insn = f; insn;)
2354 {
2355 if (GET_CODE (insn) == BARRIER)
2356 {
2357 insn = NEXT_INSN (insn);
2358
2359 never_reached_warning (insn);
2360
2361 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
2362 {
2363 if (GET_CODE (insn) == NOTE
2364 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2365 insn = NEXT_INSN (insn);
2366 else
2367 insn = delete_insn (insn);
2368 }
2369 /* INSN is now the code_label. */
2370 }
2371 /* Also remove (set (pc) (pc)) insns which can be created by
2372 gcse. We eliminate such insns now to avoid having them
2373 cause problems later. */
2374 else if (GET_CODE (insn) == JUMP_INSN
2375 && GET_CODE (PATTERN (insn)) == SET
2376 && SET_SRC (PATTERN (insn)) == pc_rtx
2377 && SET_DEST (PATTERN (insn)) == pc_rtx)
2378 insn = delete_insn (insn);
2379
2380 else
2381 insn = NEXT_INSN (insn);
2382 }
2383 }
2384
2385 /* Mark the label each jump jumps to.
2386 Combine consecutive labels, and count uses of labels.
2387
2388 For each label, make a chain (using `jump_chain')
2389 of all the *unconditional* jumps that jump to it;
2390 also make a chain of all returns.
2391
2392 CROSS_JUMP indicates whether we are doing cross jumping
2393 and if we are whether we will be paying attention to
2394 death notes or not. */
2395
2396 static void
2397 mark_all_labels (f, cross_jump)
2398 rtx f;
2399 int cross_jump;
2400 {
2401 rtx insn;
2402
2403 for (insn = f; insn; insn = NEXT_INSN (insn))
2404 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2405 {
2406 mark_jump_label (PATTERN (insn), insn, cross_jump);
2407 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
2408 {
2409 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2410 {
2411 jump_chain[INSN_UID (insn)]
2412 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2413 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2414 }
2415 if (GET_CODE (PATTERN (insn)) == RETURN)
2416 {
2417 jump_chain[INSN_UID (insn)] = jump_chain[0];
2418 jump_chain[0] = insn;
2419 }
2420 }
2421 }
2422 }
2423
2424 /* Delete all labels already not referenced.
2425 Also find and return the last insn. */
2426
2427 static rtx
2428 delete_unreferenced_labels (f)
2429 rtx f;
2430 {
2431 rtx final = NULL_RTX;
2432 rtx insn;
2433
2434 for (insn = f; insn; )
2435 {
2436 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
2437 insn = delete_insn (insn);
2438 else
2439 {
2440 final = insn;
2441 insn = NEXT_INSN (insn);
2442 }
2443 }
2444
2445 return final;
2446 }
2447
2448 /* Delete various simple forms of moves which have no necessary
2449 side effect. */
2450
2451 static void
2452 delete_noop_moves (f)
2453 rtx f;
2454 {
2455 rtx insn, next;
2456
2457 for (insn = f; insn; )
2458 {
2459 next = NEXT_INSN (insn);
2460
2461 if (GET_CODE (insn) == INSN)
2462 {
2463 register rtx body = PATTERN (insn);
2464
2465 /* Combine stack_adjusts with following push_insns. */
2466 #ifdef PUSH_ROUNDING
2467 if (GET_CODE (body) == SET
2468 && SET_DEST (body) == stack_pointer_rtx
2469 && GET_CODE (SET_SRC (body)) == PLUS
2470 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
2471 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
2472 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
2473 {
2474 rtx p;
2475 rtx stack_adjust_insn = insn;
2476 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
2477 int total_pushed = 0;
2478 int pushes = 0;
2479
2480 /* Find all successive push insns. */
2481 p = insn;
2482 /* Don't convert more than three pushes;
2483 that starts adding too many displaced addresses
2484 and the whole thing starts becoming a losing
2485 proposition. */
2486 while (pushes < 3)
2487 {
2488 rtx pbody, dest;
2489 p = next_nonnote_insn (p);
2490 if (p == 0 || GET_CODE (p) != INSN)
2491 break;
2492 pbody = PATTERN (p);
2493 if (GET_CODE (pbody) != SET)
2494 break;
2495 dest = SET_DEST (pbody);
2496 /* Allow a no-op move between the adjust and the push. */
2497 if (GET_CODE (dest) == REG
2498 && GET_CODE (SET_SRC (pbody)) == REG
2499 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2500 continue;
2501 if (! (GET_CODE (dest) == MEM
2502 && GET_CODE (XEXP (dest, 0)) == POST_INC
2503 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2504 break;
2505 pushes++;
2506 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
2507 > stack_adjust_amount)
2508 break;
2509 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2510 }
2511
2512 /* Discard the amount pushed from the stack adjust;
2513 maybe eliminate it entirely. */
2514 if (total_pushed >= stack_adjust_amount)
2515 {
2516 delete_computation (stack_adjust_insn);
2517 total_pushed = stack_adjust_amount;
2518 }
2519 else
2520 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
2521 = GEN_INT (stack_adjust_amount - total_pushed);
2522
2523 /* Change the appropriate push insns to ordinary stores. */
2524 p = insn;
2525 while (total_pushed > 0)
2526 {
2527 rtx pbody, dest;
2528 p = next_nonnote_insn (p);
2529 if (GET_CODE (p) != INSN)
2530 break;
2531 pbody = PATTERN (p);
2532 if (GET_CODE (pbody) != SET)
2533 break;
2534 dest = SET_DEST (pbody);
2535 /* Allow a no-op move between the adjust and the push. */
2536 if (GET_CODE (dest) == REG
2537 && GET_CODE (SET_SRC (pbody)) == REG
2538 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2539 continue;
2540 if (! (GET_CODE (dest) == MEM
2541 && GET_CODE (XEXP (dest, 0)) == POST_INC
2542 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2543 break;
2544 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2545 /* If this push doesn't fully fit in the space
2546 of the stack adjust that we deleted,
2547 make another stack adjust here for what we
2548 didn't use up. There should be peepholes
2549 to recognize the resulting sequence of insns. */
2550 if (total_pushed < 0)
2551 {
2552 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
2553 GEN_INT (- total_pushed)),
2554 p);
2555 break;
2556 }
2557 XEXP (dest, 0)
2558 = plus_constant (stack_pointer_rtx, total_pushed);
2559 }
2560 }
2561 #endif
2562
2563 /* Detect and delete no-op move instructions
2564 resulting from not allocating a parameter in a register. */
2565
2566 if (GET_CODE (body) == SET
2567 && (SET_DEST (body) == SET_SRC (body)
2568 || (GET_CODE (SET_DEST (body)) == MEM
2569 && GET_CODE (SET_SRC (body)) == MEM
2570 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
2571 && ! (GET_CODE (SET_DEST (body)) == MEM
2572 && MEM_VOLATILE_P (SET_DEST (body)))
2573 && ! (GET_CODE (SET_SRC (body)) == MEM
2574 && MEM_VOLATILE_P (SET_SRC (body))))
2575 delete_computation (insn);
2576
2577 /* Detect and ignore no-op move instructions
2578 resulting from smart or fortuitous register allocation. */
2579
2580 else if (GET_CODE (body) == SET)
2581 {
2582 int sreg = true_regnum (SET_SRC (body));
2583 int dreg = true_regnum (SET_DEST (body));
2584
2585 if (sreg == dreg && sreg >= 0)
2586 delete_insn (insn);
2587 else if (sreg >= 0 && dreg >= 0)
2588 {
2589 rtx trial;
2590 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
2591 sreg, NULL_PTR, dreg,
2592 GET_MODE (SET_SRC (body)));
2593
2594 if (tem != 0
2595 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
2596 {
2597 /* DREG may have been the target of a REG_DEAD note in
2598 the insn which makes INSN redundant. If so, reorg
2599 would still think it is dead. So search for such a
2600 note and delete it if we find it. */
2601 if (! find_regno_note (insn, REG_UNUSED, dreg))
2602 for (trial = prev_nonnote_insn (insn);
2603 trial && GET_CODE (trial) != CODE_LABEL;
2604 trial = prev_nonnote_insn (trial))
2605 if (find_regno_note (trial, REG_DEAD, dreg))
2606 {
2607 remove_death (dreg, trial);
2608 break;
2609 }
2610
2611 /* Deleting insn could lose a death-note for SREG. */
2612 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
2613 {
2614 /* Change this into a USE so that we won't emit
2615 code for it, but still can keep the note. */
2616 PATTERN (insn)
2617 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
2618 INSN_CODE (insn) = -1;
2619 /* Remove all reg notes but the REG_DEAD one. */
2620 REG_NOTES (insn) = trial;
2621 XEXP (trial, 1) = NULL_RTX;
2622 }
2623 else
2624 delete_insn (insn);
2625 }
2626 }
2627 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
2628 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
2629 NULL_PTR, 0,
2630 GET_MODE (SET_DEST (body))))
2631 {
2632 /* This handles the case where we have two consecutive
2633 assignments of the same constant to pseudos that didn't
2634 get a hard reg. Each SET from the constant will be
2635 converted into a SET of the spill register and an
2636 output reload will be made following it. This produces
2637 two loads of the same constant into the same spill
2638 register. */
2639
2640 rtx in_insn = insn;
2641
2642 /* Look back for a death note for the first reg.
2643 If there is one, it is no longer accurate. */
2644 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
2645 {
2646 if ((GET_CODE (in_insn) == INSN
2647 || GET_CODE (in_insn) == JUMP_INSN)
2648 && find_regno_note (in_insn, REG_DEAD, dreg))
2649 {
2650 remove_death (dreg, in_insn);
2651 break;
2652 }
2653 in_insn = PREV_INSN (in_insn);
2654 }
2655
2656 /* Delete the second load of the value. */
2657 delete_insn (insn);
2658 }
2659 }
2660 else if (GET_CODE (body) == PARALLEL)
2661 {
2662 /* If each part is a set between two identical registers or
2663 a USE or CLOBBER, delete the insn. */
2664 int i, sreg, dreg;
2665 rtx tem;
2666
2667 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
2668 {
2669 tem = XVECEXP (body, 0, i);
2670 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
2671 continue;
2672
2673 if (GET_CODE (tem) != SET
2674 || (sreg = true_regnum (SET_SRC (tem))) < 0
2675 || (dreg = true_regnum (SET_DEST (tem))) < 0
2676 || dreg != sreg)
2677 break;
2678 }
2679
2680 if (i < 0)
2681 delete_insn (insn);
2682 }
2683 /* Also delete insns to store bit fields if they are no-ops. */
2684 /* Not worth the hair to detect this in the big-endian case. */
2685 else if (! BYTES_BIG_ENDIAN
2686 && GET_CODE (body) == SET
2687 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
2688 && XEXP (SET_DEST (body), 2) == const0_rtx
2689 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
2690 && ! (GET_CODE (SET_SRC (body)) == MEM
2691 && MEM_VOLATILE_P (SET_SRC (body))))
2692 delete_insn (insn);
2693 }
2694 insn = next;
2695 }
2696 }
2697
2698 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2699 If so indicate that this function can drop off the end by returning
2700 1, else return 0.
2701
2702 CHECK_DELETED indicates whether we must check if the note being
2703 searched for has the deleted flag set.
2704
2705 DELETE_FINAL_NOTE indicates whether we should delete the note
2706 if we find it. */
2707
2708 static int
2709 calculate_can_reach_end (last, check_deleted, delete_final_note)
2710 rtx last;
2711 int check_deleted;
2712 int delete_final_note;
2713 {
2714 rtx insn = last;
2715 int n_labels = 1;
2716
2717 while (insn != NULL_RTX)
2718 {
2719 int ok = 0;
2720
2721 /* One label can follow the end-note: the return label. */
2722 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2723 ok = 1;
2724 /* Ordinary insns can follow it if returning a structure. */
2725 else if (GET_CODE (insn) == INSN)
2726 ok = 1;
2727 /* If machine uses explicit RETURN insns, no epilogue,
2728 then one of them follows the note. */
2729 else if (GET_CODE (insn) == JUMP_INSN
2730 && GET_CODE (PATTERN (insn)) == RETURN)
2731 ok = 1;
2732 /* A barrier can follow the return insn. */
2733 else if (GET_CODE (insn) == BARRIER)
2734 ok = 1;
2735 /* Other kinds of notes can follow also. */
2736 else if (GET_CODE (insn) == NOTE
2737 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2738 ok = 1;
2739
2740 if (ok != 1)
2741 break;
2742
2743 insn = PREV_INSN (insn);
2744 }
2745
2746 /* See if we backed up to the appropriate type of note. */
2747 if (insn != NULL_RTX
2748 && GET_CODE (insn) == NOTE
2749 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
2750 && (check_deleted == 0
2751 || ! INSN_DELETED_P (insn)))
2752 {
2753 if (delete_final_note)
2754 delete_insn (insn);
2755 return 1;
2756 }
2757
2758 return 0;
2759 }
2760
2761 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2762 jump. Assume that this unconditional jump is to the exit test code. If
2763 the code is sufficiently simple, make a copy of it before INSN,
2764 followed by a jump to the exit of the loop. Then delete the unconditional
2765 jump after INSN.
2766
2767 Return 1 if we made the change, else 0.
2768
2769 This is only safe immediately after a regscan pass because it uses the
2770 values of regno_first_uid and regno_last_uid. */
2771
2772 static int
2773 duplicate_loop_exit_test (loop_start)
2774 rtx loop_start;
2775 {
2776 rtx insn, set, reg, p, link;
2777 rtx copy = 0, first_copy = 0;
2778 int num_insns = 0;
2779 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2780 rtx lastexit;
2781 int max_reg = max_reg_num ();
2782 rtx *reg_map = 0;
2783
2784 /* Scan the exit code. We do not perform this optimization if any insn:
2785
2786 is a CALL_INSN
2787 is a CODE_LABEL
2788 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2789 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2790 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2791 is not valid.
2792
2793 We also do not do this if we find an insn with ASM_OPERANDS. While
2794 this restriction should not be necessary, copying an insn with
2795 ASM_OPERANDS can confuse asm_noperands in some cases.
2796
2797 Also, don't do this if the exit code is more than 20 insns. */
2798
2799 for (insn = exitcode;
2800 insn
2801 && ! (GET_CODE (insn) == NOTE
2802 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2803 insn = NEXT_INSN (insn))
2804 {
2805 switch (GET_CODE (insn))
2806 {
2807 case CODE_LABEL:
2808 case CALL_INSN:
2809 return 0;
2810 case NOTE:
2811 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2812 a jump immediately after the loop start that branches outside
2813 the loop but within an outer loop, near the exit test.
2814 If we copied this exit test and created a phony
2815 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2816 before the exit test look like these could be safely moved
2817 out of the loop even if they actually may be never executed.
2818 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2819
2820 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2821 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2822 return 0;
2823
2824 if (optimize < 2
2825 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2826 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
2827 /* If we were to duplicate this code, we would not move
2828 the BLOCK notes, and so debugging the moved code would
2829 be difficult. Thus, we only move the code with -O2 or
2830 higher. */
2831 return 0;
2832
2833 break;
2834 case JUMP_INSN:
2835 case INSN:
2836 /* The code below would grossly mishandle REG_WAS_0 notes,
2837 so get rid of them here. */
2838 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
2839 remove_note (insn, p);
2840 if (++num_insns > 20
2841 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2842 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2843 return 0;
2844 break;
2845 default:
2846 break;
2847 }
2848 }
2849
2850 /* Unless INSN is zero, we can do the optimization. */
2851 if (insn == 0)
2852 return 0;
2853
2854 lastexit = insn;
2855
2856 /* See if any insn sets a register only used in the loop exit code and
2857 not a user variable. If so, replace it with a new register. */
2858 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2859 if (GET_CODE (insn) == INSN
2860 && (set = single_set (insn)) != 0
2861 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2862 || (GET_CODE (reg) == SUBREG
2863 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2864 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2865 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2866 {
2867 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2868 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2869 break;
2870
2871 if (p != lastexit)
2872 {
2873 /* We can do the replacement. Allocate reg_map if this is the
2874 first replacement we found. */
2875 if (reg_map == 0)
2876 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
2877
2878 REG_LOOP_TEST_P (reg) = 1;
2879
2880 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2881 }
2882 }
2883
2884 /* Now copy each insn. */
2885 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2886 {
2887 switch (GET_CODE (insn))
2888 {
2889 case BARRIER:
2890 copy = emit_barrier_before (loop_start);
2891 break;
2892 case NOTE:
2893 /* Only copy line-number notes. */
2894 if (NOTE_LINE_NUMBER (insn) >= 0)
2895 {
2896 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2897 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2898 }
2899 break;
2900
2901 case INSN:
2902 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
2903 if (reg_map)
2904 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2905
2906 mark_jump_label (PATTERN (copy), copy, 0);
2907
2908 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2909 make them. */
2910 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2911 if (REG_NOTE_KIND (link) != REG_LABEL)
2912 REG_NOTES (copy)
2913 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2914 XEXP (link, 0),
2915 REG_NOTES (copy)));
2916 if (reg_map && REG_NOTES (copy))
2917 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2918 break;
2919
2920 case JUMP_INSN:
2921 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)), loop_start);
2922 if (reg_map)
2923 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2924 mark_jump_label (PATTERN (copy), copy, 0);
2925 if (REG_NOTES (insn))
2926 {
2927 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
2928 if (reg_map)
2929 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2930 }
2931
2932 /* If this is a simple jump, add it to the jump chain. */
2933
2934 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2935 && simplejump_p (copy))
2936 {
2937 jump_chain[INSN_UID (copy)]
2938 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2939 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2940 }
2941 break;
2942
2943 default:
2944 abort ();
2945 }
2946
2947 /* Record the first insn we copied. We need it so that we can
2948 scan the copied insns for new pseudo registers. */
2949 if (! first_copy)
2950 first_copy = copy;
2951 }
2952
2953 /* Now clean up by emitting a jump to the end label and deleting the jump
2954 at the start of the loop. */
2955 if (! copy || GET_CODE (copy) != BARRIER)
2956 {
2957 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2958 loop_start);
2959
2960 /* Record the first insn we copied. We need it so that we can
2961 scan the copied insns for new pseudo registers. This may not
2962 be strictly necessary since we should have copied at least one
2963 insn above. But I am going to be safe. */
2964 if (! first_copy)
2965 first_copy = copy;
2966
2967 mark_jump_label (PATTERN (copy), copy, 0);
2968 if (INSN_UID (copy) < max_jump_chain
2969 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2970 {
2971 jump_chain[INSN_UID (copy)]
2972 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2973 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2974 }
2975 emit_barrier_before (loop_start);
2976 }
2977
2978 /* Now scan from the first insn we copied to the last insn we copied
2979 (copy) for new pseudo registers. Do this after the code to jump to
2980 the end label since that might create a new pseudo too. */
2981 reg_scan_update (first_copy, copy, max_reg);
2982
2983 /* Mark the exit code as the virtual top of the converted loop. */
2984 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2985
2986 delete_insn (next_nonnote_insn (loop_start));
2987
2988 /* Clean up. */
2989 if (reg_map)
2990 free (reg_map);
2991
2992 return 1;
2993 }
2994 \f
2995 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2996 loop-end notes between START and END out before START. Assume that
2997 END is not such a note. START may be such a note. Returns the value
2998 of the new starting insn, which may be different if the original start
2999 was such a note. */
3000
3001 rtx
3002 squeeze_notes (start, end)
3003 rtx start, end;
3004 {
3005 rtx insn;
3006 rtx next;
3007
3008 for (insn = start; insn != end; insn = next)
3009 {
3010 next = NEXT_INSN (insn);
3011 if (GET_CODE (insn) == NOTE
3012 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
3013 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
3014 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
3015 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
3016 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
3017 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
3018 {
3019 if (insn == start)
3020 start = next;
3021 else
3022 {
3023 rtx prev = PREV_INSN (insn);
3024 PREV_INSN (insn) = PREV_INSN (start);
3025 NEXT_INSN (insn) = start;
3026 NEXT_INSN (PREV_INSN (insn)) = insn;
3027 PREV_INSN (NEXT_INSN (insn)) = insn;
3028 NEXT_INSN (prev) = next;
3029 PREV_INSN (next) = prev;
3030 }
3031 }
3032 }
3033
3034 return start;
3035 }
3036 \f
3037 /* Compare the instructions before insn E1 with those before E2
3038 to find an opportunity for cross jumping.
3039 (This means detecting identical sequences of insns followed by
3040 jumps to the same place, or followed by a label and a jump
3041 to that label, and replacing one with a jump to the other.)
3042
3043 Assume E1 is a jump that jumps to label E2
3044 (that is not always true but it might as well be).
3045 Find the longest possible equivalent sequences
3046 and store the first insns of those sequences into *F1 and *F2.
3047 Store zero there if no equivalent preceding instructions are found.
3048
3049 We give up if we find a label in stream 1.
3050 Actually we could transfer that label into stream 2. */
3051
3052 static void
3053 find_cross_jump (e1, e2, minimum, f1, f2)
3054 rtx e1, e2;
3055 int minimum;
3056 rtx *f1, *f2;
3057 {
3058 register rtx i1 = e1, i2 = e2;
3059 register rtx p1, p2;
3060 int lose = 0;
3061
3062 rtx last1 = 0, last2 = 0;
3063 rtx afterlast1 = 0, afterlast2 = 0;
3064
3065 *f1 = 0;
3066 *f2 = 0;
3067
3068 while (1)
3069 {
3070 i1 = prev_nonnote_insn (i1);
3071
3072 i2 = PREV_INSN (i2);
3073 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
3074 i2 = PREV_INSN (i2);
3075
3076 if (i1 == 0)
3077 break;
3078
3079 /* Don't allow the range of insns preceding E1 or E2
3080 to include the other (E2 or E1). */
3081 if (i2 == e1 || i1 == e2)
3082 break;
3083
3084 /* If we will get to this code by jumping, those jumps will be
3085 tensioned to go directly to the new label (before I2),
3086 so this cross-jumping won't cost extra. So reduce the minimum. */
3087 if (GET_CODE (i1) == CODE_LABEL)
3088 {
3089 --minimum;
3090 break;
3091 }
3092
3093 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
3094 break;
3095
3096 /* Avoid moving insns across EH regions if either of the insns
3097 can throw. */
3098 if (flag_exceptions
3099 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
3100 && !in_same_eh_region (i1, i2))
3101 break;
3102
3103 p1 = PATTERN (i1);
3104 p2 = PATTERN (i2);
3105
3106 /* If this is a CALL_INSN, compare register usage information.
3107 If we don't check this on stack register machines, the two
3108 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3109 numbers of stack registers in the same basic block.
3110 If we don't check this on machines with delay slots, a delay slot may
3111 be filled that clobbers a parameter expected by the subroutine.
3112
3113 ??? We take the simple route for now and assume that if they're
3114 equal, they were constructed identically. */
3115
3116 if (GET_CODE (i1) == CALL_INSN
3117 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
3118 CALL_INSN_FUNCTION_USAGE (i2)))
3119 lose = 1;
3120
3121 #ifdef STACK_REGS
3122 /* If cross_jump_death_matters is not 0, the insn's mode
3123 indicates whether or not the insn contains any stack-like
3124 regs. */
3125
3126 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
3127 {
3128 /* If register stack conversion has already been done, then
3129 death notes must also be compared before it is certain that
3130 the two instruction streams match. */
3131
3132 rtx note;
3133 HARD_REG_SET i1_regset, i2_regset;
3134
3135 CLEAR_HARD_REG_SET (i1_regset);
3136 CLEAR_HARD_REG_SET (i2_regset);
3137
3138 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
3139 if (REG_NOTE_KIND (note) == REG_DEAD
3140 && STACK_REG_P (XEXP (note, 0)))
3141 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
3142
3143 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
3144 if (REG_NOTE_KIND (note) == REG_DEAD
3145 && STACK_REG_P (XEXP (note, 0)))
3146 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
3147
3148 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
3149
3150 lose = 1;
3151
3152 done:
3153 ;
3154 }
3155 #endif
3156
3157 /* Don't allow old-style asm or volatile extended asms to be accepted
3158 for cross jumping purposes. It is conceptually correct to allow
3159 them, since cross-jumping preserves the dynamic instruction order
3160 even though it is changing the static instruction order. However,
3161 if an asm is being used to emit an assembler pseudo-op, such as
3162 the MIPS `.set reorder' pseudo-op, then the static instruction order
3163 matters and it must be preserved. */
3164 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
3165 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
3166 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
3167 lose = 1;
3168
3169 if (lose || GET_CODE (p1) != GET_CODE (p2)
3170 || ! rtx_renumbered_equal_p (p1, p2))
3171 {
3172 /* The following code helps take care of G++ cleanups. */
3173 rtx equiv1;
3174 rtx equiv2;
3175
3176 if (!lose && GET_CODE (p1) == GET_CODE (p2)
3177 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
3178 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
3179 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
3180 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
3181 /* If the equivalences are not to a constant, they may
3182 reference pseudos that no longer exist, so we can't
3183 use them. */
3184 && CONSTANT_P (XEXP (equiv1, 0))
3185 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
3186 {
3187 rtx s1 = single_set (i1);
3188 rtx s2 = single_set (i2);
3189 if (s1 != 0 && s2 != 0
3190 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
3191 {
3192 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
3193 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
3194 if (! rtx_renumbered_equal_p (p1, p2))
3195 cancel_changes (0);
3196 else if (apply_change_group ())
3197 goto win;
3198 }
3199 }
3200
3201 /* Insns fail to match; cross jumping is limited to the following
3202 insns. */
3203
3204 #ifdef HAVE_cc0
3205 /* Don't allow the insn after a compare to be shared by
3206 cross-jumping unless the compare is also shared.
3207 Here, if either of these non-matching insns is a compare,
3208 exclude the following insn from possible cross-jumping. */
3209 if (sets_cc0_p (p1) || sets_cc0_p (p2))
3210 last1 = afterlast1, last2 = afterlast2, ++minimum;
3211 #endif
3212
3213 /* If cross-jumping here will feed a jump-around-jump
3214 optimization, this jump won't cost extra, so reduce
3215 the minimum. */
3216 if (GET_CODE (i1) == JUMP_INSN
3217 && JUMP_LABEL (i1)
3218 && prev_real_insn (JUMP_LABEL (i1)) == e1)
3219 --minimum;
3220 break;
3221 }
3222
3223 win:
3224 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
3225 {
3226 /* Ok, this insn is potentially includable in a cross-jump here. */
3227 afterlast1 = last1, afterlast2 = last2;
3228 last1 = i1, last2 = i2, --minimum;
3229 }
3230 }
3231
3232 if (minimum <= 0 && last1 != 0 && last1 != e1)
3233 *f1 = last1, *f2 = last2;
3234 }
3235
3236 static void
3237 do_cross_jump (insn, newjpos, newlpos)
3238 rtx insn, newjpos, newlpos;
3239 {
3240 /* Find an existing label at this point
3241 or make a new one if there is none. */
3242 register rtx label = get_label_before (newlpos);
3243
3244 /* Make the same jump insn jump to the new point. */
3245 if (GET_CODE (PATTERN (insn)) == RETURN)
3246 {
3247 /* Remove from jump chain of returns. */
3248 delete_from_jump_chain (insn);
3249 /* Change the insn. */
3250 PATTERN (insn) = gen_jump (label);
3251 INSN_CODE (insn) = -1;
3252 JUMP_LABEL (insn) = label;
3253 LABEL_NUSES (label)++;
3254 /* Add to new the jump chain. */
3255 if (INSN_UID (label) < max_jump_chain
3256 && INSN_UID (insn) < max_jump_chain)
3257 {
3258 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
3259 jump_chain[INSN_UID (label)] = insn;
3260 }
3261 }
3262 else
3263 redirect_jump (insn, label);
3264
3265 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
3266 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
3267 the NEWJPOS stream. */
3268
3269 while (newjpos != insn)
3270 {
3271 rtx lnote;
3272
3273 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
3274 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
3275 || REG_NOTE_KIND (lnote) == REG_EQUIV)
3276 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
3277 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
3278 remove_note (newlpos, lnote);
3279
3280 delete_insn (newjpos);
3281 newjpos = next_real_insn (newjpos);
3282 newlpos = next_real_insn (newlpos);
3283 }
3284 }
3285 \f
3286 /* Return the label before INSN, or put a new label there. */
3287
3288 rtx
3289 get_label_before (insn)
3290 rtx insn;
3291 {
3292 rtx label;
3293
3294 /* Find an existing label at this point
3295 or make a new one if there is none. */
3296 label = prev_nonnote_insn (insn);
3297
3298 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3299 {
3300 rtx prev = PREV_INSN (insn);
3301
3302 label = gen_label_rtx ();
3303 emit_label_after (label, prev);
3304 LABEL_NUSES (label) = 0;
3305 }
3306 return label;
3307 }
3308
3309 /* Return the label after INSN, or put a new label there. */
3310
3311 rtx
3312 get_label_after (insn)
3313 rtx insn;
3314 {
3315 rtx label;
3316
3317 /* Find an existing label at this point
3318 or make a new one if there is none. */
3319 label = next_nonnote_insn (insn);
3320
3321 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3322 {
3323 label = gen_label_rtx ();
3324 emit_label_after (label, insn);
3325 LABEL_NUSES (label) = 0;
3326 }
3327 return label;
3328 }
3329 \f
3330 /* Return 1 if INSN is a jump that jumps to right after TARGET
3331 only on the condition that TARGET itself would drop through.
3332 Assumes that TARGET is a conditional jump. */
3333
3334 static int
3335 jump_back_p (insn, target)
3336 rtx insn, target;
3337 {
3338 rtx cinsn, ctarget;
3339 enum rtx_code codei, codet;
3340
3341 if (simplejump_p (insn) || ! condjump_p (insn)
3342 || simplejump_p (target)
3343 || target != prev_real_insn (JUMP_LABEL (insn)))
3344 return 0;
3345
3346 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
3347 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
3348
3349 codei = GET_CODE (cinsn);
3350 codet = GET_CODE (ctarget);
3351
3352 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
3353 {
3354 if (! can_reverse_comparison_p (cinsn, insn))
3355 return 0;
3356 codei = reverse_condition (codei);
3357 }
3358
3359 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
3360 {
3361 if (! can_reverse_comparison_p (ctarget, target))
3362 return 0;
3363 codet = reverse_condition (codet);
3364 }
3365
3366 return (codei == codet
3367 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
3368 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
3369 }
3370 \f
3371 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3372 return non-zero if it is safe to reverse this comparison. It is if our
3373 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3374 this is known to be an integer comparison. */
3375
3376 int
3377 can_reverse_comparison_p (comparison, insn)
3378 rtx comparison;
3379 rtx insn;
3380 {
3381 rtx arg0;
3382
3383 /* If this is not actually a comparison, we can't reverse it. */
3384 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
3385 return 0;
3386
3387 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3388 /* If this is an NE comparison, it is safe to reverse it to an EQ
3389 comparison and vice versa, even for floating point. If no operands
3390 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3391 always false and NE is always true, so the reversal is also valid. */
3392 || flag_fast_math
3393 || GET_CODE (comparison) == NE
3394 || GET_CODE (comparison) == EQ)
3395 return 1;
3396
3397 arg0 = XEXP (comparison, 0);
3398
3399 /* Make sure ARG0 is one of the actual objects being compared. If we
3400 can't do this, we can't be sure the comparison can be reversed.
3401
3402 Handle cc0 and a MODE_CC register. */
3403 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
3404 #ifdef HAVE_cc0
3405 || arg0 == cc0_rtx
3406 #endif
3407 )
3408 {
3409 rtx prev = prev_nonnote_insn (insn);
3410 rtx set;
3411
3412 /* First see if the condition code mode alone if enough to say we can
3413 reverse the condition. If not, then search backwards for a set of
3414 ARG0. We do not need to check for an insn clobbering it since valid
3415 code will contain set a set with no intervening clobber. But
3416 stop when we reach a label. */
3417 #ifdef REVERSIBLE_CC_MODE
3418 if (GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC
3419 && REVERSIBLE_CC_MODE (GET_MODE (arg0)))
3420 return 1;
3421 #endif
3422
3423 for (prev = prev_nonnote_insn (insn);
3424 prev != 0 && GET_CODE (prev) != CODE_LABEL;
3425 prev = prev_nonnote_insn (prev))
3426 if ((set = single_set (prev)) != 0
3427 && rtx_equal_p (SET_DEST (set), arg0))
3428 {
3429 arg0 = SET_SRC (set);
3430
3431 if (GET_CODE (arg0) == COMPARE)
3432 arg0 = XEXP (arg0, 0);
3433 break;
3434 }
3435 }
3436
3437 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3438 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3439 return (GET_CODE (arg0) == CONST_INT
3440 || (GET_MODE (arg0) != VOIDmode
3441 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
3442 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
3443 }
3444
3445 /* Given an rtx-code for a comparison, return the code
3446 for the negated comparison.
3447 WATCH OUT! reverse_condition is not safe to use on a jump
3448 that might be acting on the results of an IEEE floating point comparison,
3449 because of the special treatment of non-signaling nans in comparisons.
3450 Use can_reverse_comparison_p to be sure. */
3451
3452 enum rtx_code
3453 reverse_condition (code)
3454 enum rtx_code code;
3455 {
3456 switch (code)
3457 {
3458 case EQ:
3459 return NE;
3460
3461 case NE:
3462 return EQ;
3463
3464 case GT:
3465 return LE;
3466
3467 case GE:
3468 return LT;
3469
3470 case LT:
3471 return GE;
3472
3473 case LE:
3474 return GT;
3475
3476 case GTU:
3477 return LEU;
3478
3479 case GEU:
3480 return LTU;
3481
3482 case LTU:
3483 return GEU;
3484
3485 case LEU:
3486 return GTU;
3487
3488 default:
3489 abort ();
3490 return UNKNOWN;
3491 }
3492 }
3493
3494 /* Similar, but return the code when two operands of a comparison are swapped.
3495 This IS safe for IEEE floating-point. */
3496
3497 enum rtx_code
3498 swap_condition (code)
3499 enum rtx_code code;
3500 {
3501 switch (code)
3502 {
3503 case EQ:
3504 case NE:
3505 return code;
3506
3507 case GT:
3508 return LT;
3509
3510 case GE:
3511 return LE;
3512
3513 case LT:
3514 return GT;
3515
3516 case LE:
3517 return GE;
3518
3519 case GTU:
3520 return LTU;
3521
3522 case GEU:
3523 return LEU;
3524
3525 case LTU:
3526 return GTU;
3527
3528 case LEU:
3529 return GEU;
3530
3531 default:
3532 abort ();
3533 return UNKNOWN;
3534 }
3535 }
3536
3537 /* Given a comparison CODE, return the corresponding unsigned comparison.
3538 If CODE is an equality comparison or already an unsigned comparison,
3539 CODE is returned. */
3540
3541 enum rtx_code
3542 unsigned_condition (code)
3543 enum rtx_code code;
3544 {
3545 switch (code)
3546 {
3547 case EQ:
3548 case NE:
3549 case GTU:
3550 case GEU:
3551 case LTU:
3552 case LEU:
3553 return code;
3554
3555 case GT:
3556 return GTU;
3557
3558 case GE:
3559 return GEU;
3560
3561 case LT:
3562 return LTU;
3563
3564 case LE:
3565 return LEU;
3566
3567 default:
3568 abort ();
3569 }
3570 }
3571
3572 /* Similarly, return the signed version of a comparison. */
3573
3574 enum rtx_code
3575 signed_condition (code)
3576 enum rtx_code code;
3577 {
3578 switch (code)
3579 {
3580 case EQ:
3581 case NE:
3582 case GT:
3583 case GE:
3584 case LT:
3585 case LE:
3586 return code;
3587
3588 case GTU:
3589 return GT;
3590
3591 case GEU:
3592 return GE;
3593
3594 case LTU:
3595 return LT;
3596
3597 case LEU:
3598 return LE;
3599
3600 default:
3601 abort ();
3602 }
3603 }
3604 \f
3605 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3606 truth of CODE1 implies the truth of CODE2. */
3607
3608 int
3609 comparison_dominates_p (code1, code2)
3610 enum rtx_code code1, code2;
3611 {
3612 if (code1 == code2)
3613 return 1;
3614
3615 switch (code1)
3616 {
3617 case EQ:
3618 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3619 return 1;
3620 break;
3621
3622 case LT:
3623 if (code2 == LE || code2 == NE)
3624 return 1;
3625 break;
3626
3627 case GT:
3628 if (code2 == GE || code2 == NE)
3629 return 1;
3630 break;
3631
3632 case LTU:
3633 if (code2 == LEU || code2 == NE)
3634 return 1;
3635 break;
3636
3637 case GTU:
3638 if (code2 == GEU || code2 == NE)
3639 return 1;
3640 break;
3641
3642 default:
3643 break;
3644 }
3645
3646 return 0;
3647 }
3648 \f
3649 /* Return 1 if INSN is an unconditional jump and nothing else. */
3650
3651 int
3652 simplejump_p (insn)
3653 rtx insn;
3654 {
3655 return (GET_CODE (insn) == JUMP_INSN
3656 && GET_CODE (PATTERN (insn)) == SET
3657 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3658 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3659 }
3660
3661 /* Return nonzero if INSN is a (possibly) conditional jump
3662 and nothing more. */
3663
3664 int
3665 condjump_p (insn)
3666 rtx insn;
3667 {
3668 register rtx x = PATTERN (insn);
3669
3670 if (GET_CODE (x) != SET
3671 || GET_CODE (SET_DEST (x)) != PC)
3672 return 0;
3673
3674 x = SET_SRC (x);
3675 if (GET_CODE (x) == LABEL_REF)
3676 return 1;
3677 else return (GET_CODE (x) == IF_THEN_ELSE
3678 && ((GET_CODE (XEXP (x, 2)) == PC
3679 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
3680 || GET_CODE (XEXP (x, 1)) == RETURN))
3681 || (GET_CODE (XEXP (x, 1)) == PC
3682 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
3683 || GET_CODE (XEXP (x, 2)) == RETURN))));
3684
3685 return 0;
3686 }
3687
3688 /* Return nonzero if INSN is a (possibly) conditional jump inside a
3689 PARALLEL. */
3690
3691 int
3692 condjump_in_parallel_p (insn)
3693 rtx insn;
3694 {
3695 register rtx x = PATTERN (insn);
3696
3697 if (GET_CODE (x) != PARALLEL)
3698 return 0;
3699 else
3700 x = XVECEXP (x, 0, 0);
3701
3702 if (GET_CODE (x) != SET)
3703 return 0;
3704 if (GET_CODE (SET_DEST (x)) != PC)
3705 return 0;
3706 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3707 return 1;
3708 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3709 return 0;
3710 if (XEXP (SET_SRC (x), 2) == pc_rtx
3711 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3712 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3713 return 1;
3714 if (XEXP (SET_SRC (x), 1) == pc_rtx
3715 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3716 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3717 return 1;
3718 return 0;
3719 }
3720
3721 /* Return the label of a conditional jump. */
3722
3723 rtx
3724 condjump_label (insn)
3725 rtx insn;
3726 {
3727 register rtx x = PATTERN (insn);
3728
3729 if (GET_CODE (x) == PARALLEL)
3730 x = XVECEXP (x, 0, 0);
3731 if (GET_CODE (x) != SET)
3732 return NULL_RTX;
3733 if (GET_CODE (SET_DEST (x)) != PC)
3734 return NULL_RTX;
3735 x = SET_SRC (x);
3736 if (GET_CODE (x) == LABEL_REF)
3737 return x;
3738 if (GET_CODE (x) != IF_THEN_ELSE)
3739 return NULL_RTX;
3740 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
3741 return XEXP (x, 1);
3742 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
3743 return XEXP (x, 2);
3744 return NULL_RTX;
3745 }
3746
3747 /* Return true if INSN is a (possibly conditional) return insn. */
3748
3749 static int
3750 returnjump_p_1 (loc, data)
3751 rtx *loc;
3752 void *data ATTRIBUTE_UNUSED;
3753 {
3754 rtx x = *loc;
3755 return GET_CODE (x) == RETURN;
3756 }
3757
3758 int
3759 returnjump_p (insn)
3760 rtx insn;
3761 {
3762 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
3763 }
3764
3765 /* Return true if INSN is a jump that only transfers control and
3766 nothing more. */
3767
3768 int
3769 onlyjump_p (insn)
3770 rtx insn;
3771 {
3772 rtx set;
3773
3774 if (GET_CODE (insn) != JUMP_INSN)
3775 return 0;
3776
3777 set = single_set (insn);
3778 if (set == NULL)
3779 return 0;
3780 if (GET_CODE (SET_DEST (set)) != PC)
3781 return 0;
3782 if (side_effects_p (SET_SRC (set)))
3783 return 0;
3784
3785 return 1;
3786 }
3787
3788 #ifdef HAVE_cc0
3789
3790 /* Return 1 if X is an RTX that does nothing but set the condition codes
3791 and CLOBBER or USE registers.
3792 Return -1 if X does explicitly set the condition codes,
3793 but also does other things. */
3794
3795 int
3796 sets_cc0_p (x)
3797 rtx x ATTRIBUTE_UNUSED;
3798 {
3799 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3800 return 1;
3801 if (GET_CODE (x) == PARALLEL)
3802 {
3803 int i;
3804 int sets_cc0 = 0;
3805 int other_things = 0;
3806 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3807 {
3808 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3809 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3810 sets_cc0 = 1;
3811 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3812 other_things = 1;
3813 }
3814 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3815 }
3816 return 0;
3817 }
3818 #endif
3819 \f
3820 /* Follow any unconditional jump at LABEL;
3821 return the ultimate label reached by any such chain of jumps.
3822 If LABEL is not followed by a jump, return LABEL.
3823 If the chain loops or we can't find end, return LABEL,
3824 since that tells caller to avoid changing the insn.
3825
3826 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3827 a USE or CLOBBER. */
3828
3829 rtx
3830 follow_jumps (label)
3831 rtx label;
3832 {
3833 register rtx insn;
3834 register rtx next;
3835 register rtx value = label;
3836 register int depth;
3837
3838 for (depth = 0;
3839 (depth < 10
3840 && (insn = next_active_insn (value)) != 0
3841 && GET_CODE (insn) == JUMP_INSN
3842 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3843 || GET_CODE (PATTERN (insn)) == RETURN)
3844 && (next = NEXT_INSN (insn))
3845 && GET_CODE (next) == BARRIER);
3846 depth++)
3847 {
3848 /* Don't chain through the insn that jumps into a loop
3849 from outside the loop,
3850 since that would create multiple loop entry jumps
3851 and prevent loop optimization. */
3852 rtx tem;
3853 if (!reload_completed)
3854 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3855 if (GET_CODE (tem) == NOTE
3856 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3857 /* ??? Optional. Disables some optimizations, but makes
3858 gcov output more accurate with -O. */
3859 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3860 return value;
3861
3862 /* If we have found a cycle, make the insn jump to itself. */
3863 if (JUMP_LABEL (insn) == label)
3864 return label;
3865
3866 tem = next_active_insn (JUMP_LABEL (insn));
3867 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3868 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3869 break;
3870
3871 value = JUMP_LABEL (insn);
3872 }
3873 if (depth == 10)
3874 return label;
3875 return value;
3876 }
3877
3878 /* Assuming that field IDX of X is a vector of label_refs,
3879 replace each of them by the ultimate label reached by it.
3880 Return nonzero if a change is made.
3881 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3882
3883 static int
3884 tension_vector_labels (x, idx)
3885 register rtx x;
3886 register int idx;
3887 {
3888 int changed = 0;
3889 register int i;
3890 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3891 {
3892 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3893 register rtx nlabel = follow_jumps (olabel);
3894 if (nlabel && nlabel != olabel)
3895 {
3896 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3897 ++LABEL_NUSES (nlabel);
3898 if (--LABEL_NUSES (olabel) == 0)
3899 delete_insn (olabel);
3900 changed = 1;
3901 }
3902 }
3903 return changed;
3904 }
3905 \f
3906 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3907 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3908 in INSN, then store one of them in JUMP_LABEL (INSN).
3909 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3910 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3911 Also, when there are consecutive labels, canonicalize on the last of them.
3912
3913 Note that two labels separated by a loop-beginning note
3914 must be kept distinct if we have not yet done loop-optimization,
3915 because the gap between them is where loop-optimize
3916 will want to move invariant code to. CROSS_JUMP tells us
3917 that loop-optimization is done with.
3918
3919 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3920 two labels distinct if they are separated by only USE or CLOBBER insns. */
3921
3922 static void
3923 mark_jump_label (x, insn, cross_jump)
3924 register rtx x;
3925 rtx insn;
3926 int cross_jump;
3927 {
3928 register RTX_CODE code = GET_CODE (x);
3929 register int i;
3930 register const char *fmt;
3931
3932 switch (code)
3933 {
3934 case PC:
3935 case CC0:
3936 case REG:
3937 case SUBREG:
3938 case CONST_INT:
3939 case SYMBOL_REF:
3940 case CONST_DOUBLE:
3941 case CLOBBER:
3942 case CALL:
3943 return;
3944
3945 case MEM:
3946 /* If this is a constant-pool reference, see if it is a label. */
3947 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3948 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3949 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3950 break;
3951
3952 case LABEL_REF:
3953 {
3954 rtx label = XEXP (x, 0);
3955 rtx olabel = label;
3956 rtx note;
3957 rtx next;
3958
3959 if (GET_CODE (label) != CODE_LABEL)
3960 abort ();
3961
3962 /* Ignore references to labels of containing functions. */
3963 if (LABEL_REF_NONLOCAL_P (x))
3964 break;
3965
3966 /* If there are other labels following this one,
3967 replace it with the last of the consecutive labels. */
3968 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3969 {
3970 if (GET_CODE (next) == CODE_LABEL)
3971 label = next;
3972 else if (cross_jump && GET_CODE (next) == INSN
3973 && (GET_CODE (PATTERN (next)) == USE
3974 || GET_CODE (PATTERN (next)) == CLOBBER))
3975 continue;
3976 else if (GET_CODE (next) != NOTE)
3977 break;
3978 else if (! cross_jump
3979 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3980 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3981 /* ??? Optional. Disables some optimizations, but
3982 makes gcov output more accurate with -O. */
3983 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3984 break;
3985 }
3986
3987 XEXP (x, 0) = label;
3988 if (! insn || ! INSN_DELETED_P (insn))
3989 ++LABEL_NUSES (label);
3990
3991 if (insn)
3992 {
3993 if (GET_CODE (insn) == JUMP_INSN)
3994 JUMP_LABEL (insn) = label;
3995
3996 /* If we've changed OLABEL and we had a REG_LABEL note
3997 for it, update it as well. */
3998 else if (label != olabel
3999 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
4000 XEXP (note, 0) = label;
4001
4002 /* Otherwise, add a REG_LABEL note for LABEL unless there already
4003 is one. */
4004 else if (! find_reg_note (insn, REG_LABEL, label))
4005 {
4006 /* This code used to ignore labels which refered to dispatch
4007 tables to avoid flow.c generating worse code.
4008
4009 However, in the presense of global optimizations like
4010 gcse which call find_basic_blocks without calling
4011 life_analysis, not recording such labels will lead
4012 to compiler aborts because of inconsistencies in the
4013 flow graph. So we go ahead and record the label.
4014
4015 It may also be the case that the optimization argument
4016 is no longer valid because of the more accurate cfg
4017 we build in find_basic_blocks -- it no longer pessimizes
4018 code when it finds a REG_LABEL note. */
4019 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
4020 REG_NOTES (insn));
4021 }
4022 }
4023 return;
4024 }
4025
4026 /* Do walk the labels in a vector, but not the first operand of an
4027 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
4028 case ADDR_VEC:
4029 case ADDR_DIFF_VEC:
4030 if (! INSN_DELETED_P (insn))
4031 {
4032 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
4033
4034 for (i = 0; i < XVECLEN (x, eltnum); i++)
4035 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
4036 }
4037 return;
4038
4039 default:
4040 break;
4041 }
4042
4043 fmt = GET_RTX_FORMAT (code);
4044 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4045 {
4046 if (fmt[i] == 'e')
4047 mark_jump_label (XEXP (x, i), insn, cross_jump);
4048 else if (fmt[i] == 'E')
4049 {
4050 register int j;
4051 for (j = 0; j < XVECLEN (x, i); j++)
4052 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
4053 }
4054 }
4055 }
4056
4057 /* If all INSN does is set the pc, delete it,
4058 and delete the insn that set the condition codes for it
4059 if that's what the previous thing was. */
4060
4061 void
4062 delete_jump (insn)
4063 rtx insn;
4064 {
4065 register rtx set = single_set (insn);
4066
4067 if (set && GET_CODE (SET_DEST (set)) == PC)
4068 delete_computation (insn);
4069 }
4070
4071 /* Verify INSN is a BARRIER and delete it. */
4072
4073 void
4074 delete_barrier (insn)
4075 rtx insn;
4076 {
4077 if (GET_CODE (insn) != BARRIER)
4078 abort ();
4079
4080 delete_insn (insn);
4081 }
4082
4083 /* Recursively delete prior insns that compute the value (used only by INSN
4084 which the caller is deleting) stored in the register mentioned by NOTE
4085 which is a REG_DEAD note associated with INSN. */
4086
4087 static void
4088 delete_prior_computation (note, insn)
4089 rtx note;
4090 rtx insn;
4091 {
4092 rtx our_prev;
4093 rtx reg = XEXP (note, 0);
4094
4095 for (our_prev = prev_nonnote_insn (insn);
4096 our_prev && (GET_CODE (our_prev) == INSN
4097 || GET_CODE (our_prev) == CALL_INSN);
4098 our_prev = prev_nonnote_insn (our_prev))
4099 {
4100 rtx pat = PATTERN (our_prev);
4101
4102 /* If we reach a CALL which is not calling a const function
4103 or the callee pops the arguments, then give up. */
4104 if (GET_CODE (our_prev) == CALL_INSN
4105 && (! CONST_CALL_P (our_prev)
4106 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
4107 break;
4108
4109 /* If we reach a SEQUENCE, it is too complex to try to
4110 do anything with it, so give up. */
4111 if (GET_CODE (pat) == SEQUENCE)
4112 break;
4113
4114 if (GET_CODE (pat) == USE
4115 && GET_CODE (XEXP (pat, 0)) == INSN)
4116 /* reorg creates USEs that look like this. We leave them
4117 alone because reorg needs them for its own purposes. */
4118 break;
4119
4120 if (reg_set_p (reg, pat))
4121 {
4122 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
4123 break;
4124
4125 if (GET_CODE (pat) == PARALLEL)
4126 {
4127 /* If we find a SET of something else, we can't
4128 delete the insn. */
4129
4130 int i;
4131
4132 for (i = 0; i < XVECLEN (pat, 0); i++)
4133 {
4134 rtx part = XVECEXP (pat, 0, i);
4135
4136 if (GET_CODE (part) == SET
4137 && SET_DEST (part) != reg)
4138 break;
4139 }
4140
4141 if (i == XVECLEN (pat, 0))
4142 delete_computation (our_prev);
4143 }
4144 else if (GET_CODE (pat) == SET
4145 && GET_CODE (SET_DEST (pat)) == REG)
4146 {
4147 int dest_regno = REGNO (SET_DEST (pat));
4148 int dest_endregno
4149 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
4150 ? HARD_REGNO_NREGS (dest_regno,
4151 GET_MODE (SET_DEST (pat))) : 1);
4152 int regno = REGNO (reg);
4153 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
4154 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
4155
4156 if (dest_regno >= regno
4157 && dest_endregno <= endregno)
4158 delete_computation (our_prev);
4159
4160 /* We may have a multi-word hard register and some, but not
4161 all, of the words of the register are needed in subsequent
4162 insns. Write REG_UNUSED notes for those parts that were not
4163 needed. */
4164 else if (dest_regno <= regno
4165 && dest_endregno >= endregno)
4166 {
4167 int i;
4168
4169 REG_NOTES (our_prev)
4170 = gen_rtx_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (our_prev));
4171
4172 for (i = dest_regno; i < dest_endregno; i++)
4173 if (! find_regno_note (our_prev, REG_UNUSED, i))
4174 break;
4175
4176 if (i == dest_endregno)
4177 delete_computation (our_prev);
4178 }
4179 }
4180
4181 break;
4182 }
4183
4184 /* If PAT references the register that dies here, it is an
4185 additional use. Hence any prior SET isn't dead. However, this
4186 insn becomes the new place for the REG_DEAD note. */
4187 if (reg_overlap_mentioned_p (reg, pat))
4188 {
4189 XEXP (note, 1) = REG_NOTES (our_prev);
4190 REG_NOTES (our_prev) = note;
4191 break;
4192 }
4193 }
4194 }
4195
4196 /* Delete INSN and recursively delete insns that compute values used only
4197 by INSN. This uses the REG_DEAD notes computed during flow analysis.
4198 If we are running before flow.c, we need do nothing since flow.c will
4199 delete dead code. We also can't know if the registers being used are
4200 dead or not at this point.
4201
4202 Otherwise, look at all our REG_DEAD notes. If a previous insn does
4203 nothing other than set a register that dies in this insn, we can delete
4204 that insn as well.
4205
4206 On machines with CC0, if CC0 is used in this insn, we may be able to
4207 delete the insn that set it. */
4208
4209 static void
4210 delete_computation (insn)
4211 rtx insn;
4212 {
4213 rtx note, next;
4214 rtx set;
4215
4216 #ifdef HAVE_cc0
4217 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
4218 {
4219 rtx prev = prev_nonnote_insn (insn);
4220 /* We assume that at this stage
4221 CC's are always set explicitly
4222 and always immediately before the jump that
4223 will use them. So if the previous insn
4224 exists to set the CC's, delete it
4225 (unless it performs auto-increments, etc.). */
4226 if (prev && GET_CODE (prev) == INSN
4227 && sets_cc0_p (PATTERN (prev)))
4228 {
4229 if (sets_cc0_p (PATTERN (prev)) > 0
4230 && ! side_effects_p (PATTERN (prev)))
4231 delete_computation (prev);
4232 else
4233 /* Otherwise, show that cc0 won't be used. */
4234 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
4235 cc0_rtx, REG_NOTES (prev));
4236 }
4237 }
4238 #endif
4239
4240 #ifdef INSN_SCHEDULING
4241 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
4242 reload has completed. The schedulers need to be fixed. Until
4243 they are, we must not rely on the death notes here. */
4244 if (reload_completed && flag_schedule_insns_after_reload)
4245 {
4246 delete_insn (insn);
4247 return;
4248 }
4249 #endif
4250
4251 /* The REG_DEAD note may have been omitted for a register
4252 which is both set and used by the insn. */
4253 set = single_set (insn);
4254 if (set && GET_CODE (SET_DEST (set)) == REG)
4255 {
4256 int dest_regno = REGNO (SET_DEST (set));
4257 int dest_endregno
4258 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
4259 ? HARD_REGNO_NREGS (dest_regno,
4260 GET_MODE (SET_DEST (set))) : 1);
4261 int i;
4262
4263 for (i = dest_regno; i < dest_endregno; i++)
4264 {
4265 if (! refers_to_regno_p (i, i + 1, SET_SRC (set), NULL_PTR)
4266 || find_regno_note (insn, REG_DEAD, i))
4267 continue;
4268
4269 note = gen_rtx_EXPR_LIST (REG_DEAD, (i < FIRST_PSEUDO_REGISTER
4270 ? gen_rtx_REG (reg_raw_mode[i], i)
4271 : SET_DEST (set)), NULL_RTX);
4272 delete_prior_computation (note, insn);
4273 }
4274 }
4275
4276 for (note = REG_NOTES (insn); note; note = next)
4277 {
4278 next = XEXP (note, 1);
4279
4280 if (REG_NOTE_KIND (note) != REG_DEAD
4281 /* Verify that the REG_NOTE is legitimate. */
4282 || GET_CODE (XEXP (note, 0)) != REG)
4283 continue;
4284
4285 delete_prior_computation (note, insn);
4286 }
4287
4288 delete_insn (insn);
4289 }
4290 \f
4291 /* Delete insn INSN from the chain of insns and update label ref counts.
4292 May delete some following insns as a consequence; may even delete
4293 a label elsewhere and insns that follow it.
4294
4295 Returns the first insn after INSN that was not deleted. */
4296
4297 rtx
4298 delete_insn (insn)
4299 register rtx insn;
4300 {
4301 register rtx next = NEXT_INSN (insn);
4302 register rtx prev = PREV_INSN (insn);
4303 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
4304 register int dont_really_delete = 0;
4305
4306 while (next && INSN_DELETED_P (next))
4307 next = NEXT_INSN (next);
4308
4309 /* This insn is already deleted => return first following nondeleted. */
4310 if (INSN_DELETED_P (insn))
4311 return next;
4312
4313 if (was_code_label)
4314 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
4315
4316 /* Don't delete user-declared labels. Convert them to special NOTEs
4317 instead. */
4318 if (was_code_label && LABEL_NAME (insn) != 0
4319 && optimize && ! dont_really_delete)
4320 {
4321 PUT_CODE (insn, NOTE);
4322 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
4323 NOTE_SOURCE_FILE (insn) = 0;
4324 dont_really_delete = 1;
4325 }
4326 else
4327 /* Mark this insn as deleted. */
4328 INSN_DELETED_P (insn) = 1;
4329
4330 /* If this is an unconditional jump, delete it from the jump chain. */
4331 if (simplejump_p (insn))
4332 delete_from_jump_chain (insn);
4333
4334 /* If instruction is followed by a barrier,
4335 delete the barrier too. */
4336
4337 if (next != 0 && GET_CODE (next) == BARRIER)
4338 {
4339 INSN_DELETED_P (next) = 1;
4340 next = NEXT_INSN (next);
4341 }
4342
4343 /* Patch out INSN (and the barrier if any) */
4344
4345 if (optimize && ! dont_really_delete)
4346 {
4347 if (prev)
4348 {
4349 NEXT_INSN (prev) = next;
4350 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
4351 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
4352 XVECLEN (PATTERN (prev), 0) - 1)) = next;
4353 }
4354
4355 if (next)
4356 {
4357 PREV_INSN (next) = prev;
4358 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
4359 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
4360 }
4361
4362 if (prev && NEXT_INSN (prev) == 0)
4363 set_last_insn (prev);
4364 }
4365
4366 /* If deleting a jump, decrement the count of the label,
4367 and delete the label if it is now unused. */
4368
4369 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
4370 {
4371 rtx lab = JUMP_LABEL (insn), lab_next;
4372
4373 if (--LABEL_NUSES (lab) == 0)
4374 {
4375 /* This can delete NEXT or PREV,
4376 either directly if NEXT is JUMP_LABEL (INSN),
4377 or indirectly through more levels of jumps. */
4378 delete_insn (lab);
4379
4380 /* I feel a little doubtful about this loop,
4381 but I see no clean and sure alternative way
4382 to find the first insn after INSN that is not now deleted.
4383 I hope this works. */
4384 while (next && INSN_DELETED_P (next))
4385 next = NEXT_INSN (next);
4386 return next;
4387 }
4388 else if ((lab_next = next_nonnote_insn (lab)) != NULL
4389 && GET_CODE (lab_next) == JUMP_INSN
4390 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
4391 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
4392 {
4393 /* If we're deleting the tablejump, delete the dispatch table.
4394 We may not be able to kill the label immediately preceeding
4395 just yet, as it might be referenced in code leading up to
4396 the tablejump. */
4397 delete_insn (lab_next);
4398 }
4399 }
4400
4401 /* Likewise if we're deleting a dispatch table. */
4402
4403 if (GET_CODE (insn) == JUMP_INSN
4404 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
4405 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
4406 {
4407 rtx pat = PATTERN (insn);
4408 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
4409 int len = XVECLEN (pat, diff_vec_p);
4410
4411 for (i = 0; i < len; i++)
4412 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
4413 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
4414 while (next && INSN_DELETED_P (next))
4415 next = NEXT_INSN (next);
4416 return next;
4417 }
4418
4419 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
4420 prev = PREV_INSN (prev);
4421
4422 /* If INSN was a label and a dispatch table follows it,
4423 delete the dispatch table. The tablejump must have gone already.
4424 It isn't useful to fall through into a table. */
4425
4426 if (was_code_label
4427 && NEXT_INSN (insn) != 0
4428 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
4429 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
4430 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
4431 next = delete_insn (NEXT_INSN (insn));
4432
4433 /* If INSN was a label, delete insns following it if now unreachable. */
4434
4435 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
4436 {
4437 register RTX_CODE code;
4438 while (next != 0
4439 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
4440 || code == NOTE || code == BARRIER
4441 || (code == CODE_LABEL && INSN_DELETED_P (next))))
4442 {
4443 if (code == NOTE
4444 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
4445 next = NEXT_INSN (next);
4446 /* Keep going past other deleted labels to delete what follows. */
4447 else if (code == CODE_LABEL && INSN_DELETED_P (next))
4448 next = NEXT_INSN (next);
4449 else
4450 /* Note: if this deletes a jump, it can cause more
4451 deletion of unreachable code, after a different label.
4452 As long as the value from this recursive call is correct,
4453 this invocation functions correctly. */
4454 next = delete_insn (next);
4455 }
4456 }
4457
4458 return next;
4459 }
4460
4461 /* Advance from INSN till reaching something not deleted
4462 then return that. May return INSN itself. */
4463
4464 rtx
4465 next_nondeleted_insn (insn)
4466 rtx insn;
4467 {
4468 while (INSN_DELETED_P (insn))
4469 insn = NEXT_INSN (insn);
4470 return insn;
4471 }
4472 \f
4473 /* Delete a range of insns from FROM to TO, inclusive.
4474 This is for the sake of peephole optimization, so assume
4475 that whatever these insns do will still be done by a new
4476 peephole insn that will replace them. */
4477
4478 void
4479 delete_for_peephole (from, to)
4480 register rtx from, to;
4481 {
4482 register rtx insn = from;
4483
4484 while (1)
4485 {
4486 register rtx next = NEXT_INSN (insn);
4487 register rtx prev = PREV_INSN (insn);
4488
4489 if (GET_CODE (insn) != NOTE)
4490 {
4491 INSN_DELETED_P (insn) = 1;
4492
4493 /* Patch this insn out of the chain. */
4494 /* We don't do this all at once, because we
4495 must preserve all NOTEs. */
4496 if (prev)
4497 NEXT_INSN (prev) = next;
4498
4499 if (next)
4500 PREV_INSN (next) = prev;
4501 }
4502
4503 if (insn == to)
4504 break;
4505 insn = next;
4506 }
4507
4508 /* Note that if TO is an unconditional jump
4509 we *do not* delete the BARRIER that follows,
4510 since the peephole that replaces this sequence
4511 is also an unconditional jump in that case. */
4512 }
4513 \f
4514 /* We have determined that INSN is never reached, and are about to
4515 delete it. Print a warning if the user asked for one.
4516
4517 To try to make this warning more useful, this should only be called
4518 once per basic block not reached, and it only warns when the basic
4519 block contains more than one line from the current function, and
4520 contains at least one operation. CSE and inlining can duplicate insns,
4521 so it's possible to get spurious warnings from this. */
4522
4523 void
4524 never_reached_warning (avoided_insn)
4525 rtx avoided_insn;
4526 {
4527 rtx insn;
4528 rtx a_line_note = NULL;
4529 int two_avoided_lines = 0;
4530 int contains_insn = 0;
4531
4532 if (! warn_notreached)
4533 return;
4534
4535 /* Scan forwards, looking at LINE_NUMBER notes, until
4536 we hit a LABEL or we run out of insns. */
4537
4538 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
4539 {
4540 if (GET_CODE (insn) == CODE_LABEL)
4541 break;
4542 else if (GET_CODE (insn) == NOTE /* A line number note? */
4543 && NOTE_LINE_NUMBER (insn) >= 0)
4544 {
4545 if (a_line_note == NULL)
4546 a_line_note = insn;
4547 else
4548 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
4549 != NOTE_LINE_NUMBER (insn));
4550 }
4551 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
4552 contains_insn = 1;
4553 }
4554 if (two_avoided_lines && contains_insn)
4555 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
4556 NOTE_LINE_NUMBER (a_line_note),
4557 "will never be executed");
4558 }
4559 \f
4560 /* Invert the condition of the jump JUMP, and make it jump
4561 to label NLABEL instead of where it jumps now. */
4562
4563 int
4564 invert_jump (jump, nlabel)
4565 rtx jump, nlabel;
4566 {
4567 /* We have to either invert the condition and change the label or
4568 do neither. Either operation could fail. We first try to invert
4569 the jump. If that succeeds, we try changing the label. If that fails,
4570 we invert the jump back to what it was. */
4571
4572 if (! invert_exp (PATTERN (jump), jump))
4573 return 0;
4574
4575 if (redirect_jump (jump, nlabel))
4576 {
4577 if (flag_branch_probabilities)
4578 {
4579 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
4580
4581 /* An inverted jump means that a probability taken becomes a
4582 probability not taken. Subtract the branch probability from the
4583 probability base to convert it back to a taken probability.
4584 (We don't flip the probability on a branch that's never taken. */
4585 if (note && XINT (XEXP (note, 0), 0) >= 0)
4586 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
4587 }
4588
4589 return 1;
4590 }
4591
4592 if (! invert_exp (PATTERN (jump), jump))
4593 /* This should just be putting it back the way it was. */
4594 abort ();
4595
4596 return 0;
4597 }
4598
4599 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4600
4601 Return 1 if we can do so, 0 if we cannot find a way to do so that
4602 matches a pattern. */
4603
4604 int
4605 invert_exp (x, insn)
4606 rtx x;
4607 rtx insn;
4608 {
4609 register RTX_CODE code;
4610 register int i;
4611 register const char *fmt;
4612
4613 code = GET_CODE (x);
4614
4615 if (code == IF_THEN_ELSE)
4616 {
4617 register rtx comp = XEXP (x, 0);
4618 register rtx tem;
4619
4620 /* We can do this in two ways: The preferable way, which can only
4621 be done if this is not an integer comparison, is to reverse
4622 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4623 of the IF_THEN_ELSE. If we can't do either, fail. */
4624
4625 if (can_reverse_comparison_p (comp, insn)
4626 && validate_change (insn, &XEXP (x, 0),
4627 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
4628 GET_MODE (comp), XEXP (comp, 0),
4629 XEXP (comp, 1)), 0))
4630 return 1;
4631
4632 tem = XEXP (x, 1);
4633 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
4634 validate_change (insn, &XEXP (x, 2), tem, 1);
4635 return apply_change_group ();
4636 }
4637
4638 fmt = GET_RTX_FORMAT (code);
4639 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4640 {
4641 if (fmt[i] == 'e')
4642 if (! invert_exp (XEXP (x, i), insn))
4643 return 0;
4644 if (fmt[i] == 'E')
4645 {
4646 register int j;
4647 for (j = 0; j < XVECLEN (x, i); j++)
4648 if (!invert_exp (XVECEXP (x, i, j), insn))
4649 return 0;
4650 }
4651 }
4652
4653 return 1;
4654 }
4655 \f
4656 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4657 If the old jump target label is unused as a result,
4658 it and the code following it may be deleted.
4659
4660 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4661 RETURN insn.
4662
4663 The return value will be 1 if the change was made, 0 if it wasn't (this
4664 can only occur for NLABEL == 0). */
4665
4666 int
4667 redirect_jump (jump, nlabel)
4668 rtx jump, nlabel;
4669 {
4670 register rtx olabel = JUMP_LABEL (jump);
4671
4672 if (nlabel == olabel)
4673 return 1;
4674
4675 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
4676 return 0;
4677
4678 /* If this is an unconditional branch, delete it from the jump_chain of
4679 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4680 have UID's in range and JUMP_CHAIN is valid). */
4681 if (jump_chain && (simplejump_p (jump)
4682 || GET_CODE (PATTERN (jump)) == RETURN))
4683 {
4684 int label_index = nlabel ? INSN_UID (nlabel) : 0;
4685
4686 delete_from_jump_chain (jump);
4687 if (label_index < max_jump_chain
4688 && INSN_UID (jump) < max_jump_chain)
4689 {
4690 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
4691 jump_chain[label_index] = jump;
4692 }
4693 }
4694
4695 JUMP_LABEL (jump) = nlabel;
4696 if (nlabel)
4697 ++LABEL_NUSES (nlabel);
4698
4699 if (olabel && --LABEL_NUSES (olabel) == 0)
4700 delete_insn (olabel);
4701
4702 return 1;
4703 }
4704
4705 /* Delete the instruction JUMP from any jump chain it might be on. */
4706
4707 static void
4708 delete_from_jump_chain (jump)
4709 rtx jump;
4710 {
4711 int index;
4712 rtx olabel = JUMP_LABEL (jump);
4713
4714 /* Handle unconditional jumps. */
4715 if (jump_chain && olabel != 0
4716 && INSN_UID (olabel) < max_jump_chain
4717 && simplejump_p (jump))
4718 index = INSN_UID (olabel);
4719 /* Handle return insns. */
4720 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
4721 index = 0;
4722 else return;
4723
4724 if (jump_chain[index] == jump)
4725 jump_chain[index] = jump_chain[INSN_UID (jump)];
4726 else
4727 {
4728 rtx insn;
4729
4730 for (insn = jump_chain[index];
4731 insn != 0;
4732 insn = jump_chain[INSN_UID (insn)])
4733 if (jump_chain[INSN_UID (insn)] == jump)
4734 {
4735 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
4736 break;
4737 }
4738 }
4739 }
4740
4741 /* If NLABEL is nonzero, throughout the rtx at LOC,
4742 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4743 zero, alter (RETURN) to (LABEL_REF NLABEL).
4744
4745 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4746 validity with validate_change. Convert (set (pc) (label_ref olabel))
4747 to (return).
4748
4749 Return 0 if we found a change we would like to make but it is invalid.
4750 Otherwise, return 1. */
4751
4752 int
4753 redirect_exp (loc, olabel, nlabel, insn)
4754 rtx *loc;
4755 rtx olabel, nlabel;
4756 rtx insn;
4757 {
4758 register rtx x = *loc;
4759 register RTX_CODE code = GET_CODE (x);
4760 register int i;
4761 register const char *fmt;
4762
4763 if (code == LABEL_REF)
4764 {
4765 if (XEXP (x, 0) == olabel)
4766 {
4767 if (nlabel)
4768 XEXP (x, 0) = nlabel;
4769 else
4770 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4771 return 1;
4772 }
4773 }
4774 else if (code == RETURN && olabel == 0)
4775 {
4776 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4777 if (loc == &PATTERN (insn))
4778 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4779 return validate_change (insn, loc, x, 0);
4780 }
4781
4782 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4783 && GET_CODE (SET_SRC (x)) == LABEL_REF
4784 && XEXP (SET_SRC (x), 0) == olabel)
4785 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4786
4787 fmt = GET_RTX_FORMAT (code);
4788 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4789 {
4790 if (fmt[i] == 'e')
4791 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4792 return 0;
4793 if (fmt[i] == 'E')
4794 {
4795 register int j;
4796 for (j = 0; j < XVECLEN (x, i); j++)
4797 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4798 return 0;
4799 }
4800 }
4801
4802 return 1;
4803 }
4804 \f
4805 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4806
4807 If the old jump target label (before the dispatch table) becomes unused,
4808 it and the dispatch table may be deleted. In that case, find the insn
4809 before the jump references that label and delete it and logical successors
4810 too. */
4811
4812 static void
4813 redirect_tablejump (jump, nlabel)
4814 rtx jump, nlabel;
4815 {
4816 register rtx olabel = JUMP_LABEL (jump);
4817
4818 /* Add this jump to the jump_chain of NLABEL. */
4819 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4820 && INSN_UID (jump) < max_jump_chain)
4821 {
4822 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4823 jump_chain[INSN_UID (nlabel)] = jump;
4824 }
4825
4826 PATTERN (jump) = gen_jump (nlabel);
4827 JUMP_LABEL (jump) = nlabel;
4828 ++LABEL_NUSES (nlabel);
4829 INSN_CODE (jump) = -1;
4830
4831 if (--LABEL_NUSES (olabel) == 0)
4832 {
4833 delete_labelref_insn (jump, olabel, 0);
4834 delete_insn (olabel);
4835 }
4836 }
4837
4838 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4839 If we found one, delete it and then delete this insn if DELETE_THIS is
4840 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4841
4842 static int
4843 delete_labelref_insn (insn, label, delete_this)
4844 rtx insn, label;
4845 int delete_this;
4846 {
4847 int deleted = 0;
4848 rtx link;
4849
4850 if (GET_CODE (insn) != NOTE
4851 && reg_mentioned_p (label, PATTERN (insn)))
4852 {
4853 if (delete_this)
4854 {
4855 delete_insn (insn);
4856 deleted = 1;
4857 }
4858 else
4859 return 1;
4860 }
4861
4862 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4863 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4864 {
4865 if (delete_this)
4866 {
4867 delete_insn (insn);
4868 deleted = 1;
4869 }
4870 else
4871 return 1;
4872 }
4873
4874 return deleted;
4875 }
4876 \f
4877 /* Like rtx_equal_p except that it considers two REGs as equal
4878 if they renumber to the same value and considers two commutative
4879 operations to be the same if the order of the operands has been
4880 reversed.
4881
4882 ??? Addition is not commutative on the PA due to the weird implicit
4883 space register selection rules for memory addresses. Therefore, we
4884 don't consider a + b == b + a.
4885
4886 We could/should make this test a little tighter. Possibly only
4887 disabling it on the PA via some backend macro or only disabling this
4888 case when the PLUS is inside a MEM. */
4889
4890 int
4891 rtx_renumbered_equal_p (x, y)
4892 rtx x, y;
4893 {
4894 register int i;
4895 register RTX_CODE code = GET_CODE (x);
4896 register const char *fmt;
4897
4898 if (x == y)
4899 return 1;
4900
4901 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4902 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4903 && GET_CODE (SUBREG_REG (y)) == REG)))
4904 {
4905 int reg_x = -1, reg_y = -1;
4906 int word_x = 0, word_y = 0;
4907
4908 if (GET_MODE (x) != GET_MODE (y))
4909 return 0;
4910
4911 /* If we haven't done any renumbering, don't
4912 make any assumptions. */
4913 if (reg_renumber == 0)
4914 return rtx_equal_p (x, y);
4915
4916 if (code == SUBREG)
4917 {
4918 reg_x = REGNO (SUBREG_REG (x));
4919 word_x = SUBREG_WORD (x);
4920
4921 if (reg_renumber[reg_x] >= 0)
4922 {
4923 reg_x = reg_renumber[reg_x] + word_x;
4924 word_x = 0;
4925 }
4926 }
4927
4928 else
4929 {
4930 reg_x = REGNO (x);
4931 if (reg_renumber[reg_x] >= 0)
4932 reg_x = reg_renumber[reg_x];
4933 }
4934
4935 if (GET_CODE (y) == SUBREG)
4936 {
4937 reg_y = REGNO (SUBREG_REG (y));
4938 word_y = SUBREG_WORD (y);
4939
4940 if (reg_renumber[reg_y] >= 0)
4941 {
4942 reg_y = reg_renumber[reg_y];
4943 word_y = 0;
4944 }
4945 }
4946
4947 else
4948 {
4949 reg_y = REGNO (y);
4950 if (reg_renumber[reg_y] >= 0)
4951 reg_y = reg_renumber[reg_y];
4952 }
4953
4954 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4955 }
4956
4957 /* Now we have disposed of all the cases
4958 in which different rtx codes can match. */
4959 if (code != GET_CODE (y))
4960 return 0;
4961
4962 switch (code)
4963 {
4964 case PC:
4965 case CC0:
4966 case ADDR_VEC:
4967 case ADDR_DIFF_VEC:
4968 return 0;
4969
4970 case CONST_INT:
4971 return INTVAL (x) == INTVAL (y);
4972
4973 case LABEL_REF:
4974 /* We can't assume nonlocal labels have their following insns yet. */
4975 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4976 return XEXP (x, 0) == XEXP (y, 0);
4977
4978 /* Two label-refs are equivalent if they point at labels
4979 in the same position in the instruction stream. */
4980 return (next_real_insn (XEXP (x, 0))
4981 == next_real_insn (XEXP (y, 0)));
4982
4983 case SYMBOL_REF:
4984 return XSTR (x, 0) == XSTR (y, 0);
4985
4986 case CODE_LABEL:
4987 /* If we didn't match EQ equality above, they aren't the same. */
4988 return 0;
4989
4990 default:
4991 break;
4992 }
4993
4994 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4995
4996 if (GET_MODE (x) != GET_MODE (y))
4997 return 0;
4998
4999 /* For commutative operations, the RTX match if the operand match in any
5000 order. Also handle the simple binary and unary cases without a loop.
5001
5002 ??? Don't consider PLUS a commutative operator; see comments above. */
5003 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
5004 && code != PLUS)
5005 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
5006 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
5007 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
5008 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
5009 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
5010 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
5011 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
5012 else if (GET_RTX_CLASS (code) == '1')
5013 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
5014
5015 /* Compare the elements. If any pair of corresponding elements
5016 fail to match, return 0 for the whole things. */
5017
5018 fmt = GET_RTX_FORMAT (code);
5019 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5020 {
5021 register int j;
5022 switch (fmt[i])
5023 {
5024 case 'w':
5025 if (XWINT (x, i) != XWINT (y, i))
5026 return 0;
5027 break;
5028
5029 case 'i':
5030 if (XINT (x, i) != XINT (y, i))
5031 return 0;
5032 break;
5033
5034 case 's':
5035 if (strcmp (XSTR (x, i), XSTR (y, i)))
5036 return 0;
5037 break;
5038
5039 case 'e':
5040 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
5041 return 0;
5042 break;
5043
5044 case 'u':
5045 if (XEXP (x, i) != XEXP (y, i))
5046 return 0;
5047 /* fall through. */
5048 case '0':
5049 break;
5050
5051 case 'E':
5052 if (XVECLEN (x, i) != XVECLEN (y, i))
5053 return 0;
5054 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5055 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
5056 return 0;
5057 break;
5058
5059 default:
5060 abort ();
5061 }
5062 }
5063 return 1;
5064 }
5065 \f
5066 /* If X is a hard register or equivalent to one or a subregister of one,
5067 return the hard register number. If X is a pseudo register that was not
5068 assigned a hard register, return the pseudo register number. Otherwise,
5069 return -1. Any rtx is valid for X. */
5070
5071 int
5072 true_regnum (x)
5073 rtx x;
5074 {
5075 if (GET_CODE (x) == REG)
5076 {
5077 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
5078 return reg_renumber[REGNO (x)];
5079 return REGNO (x);
5080 }
5081 if (GET_CODE (x) == SUBREG)
5082 {
5083 int base = true_regnum (SUBREG_REG (x));
5084 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
5085 return SUBREG_WORD (x) + base;
5086 }
5087 return -1;
5088 }
5089 \f
5090 /* Optimize code of the form:
5091
5092 for (x = a[i]; x; ...)
5093 ...
5094 for (x = a[i]; x; ...)
5095 ...
5096 foo:
5097
5098 Loop optimize will change the above code into
5099
5100 if (x = a[i])
5101 for (;;)
5102 { ...; if (! (x = ...)) break; }
5103 if (x = a[i])
5104 for (;;)
5105 { ...; if (! (x = ...)) break; }
5106 foo:
5107
5108 In general, if the first test fails, the program can branch
5109 directly to `foo' and skip the second try which is doomed to fail.
5110 We run this after loop optimization and before flow analysis. */
5111
5112 /* When comparing the insn patterns, we track the fact that different
5113 pseudo-register numbers may have been used in each computation.
5114 The following array stores an equivalence -- same_regs[I] == J means
5115 that pseudo register I was used in the first set of tests in a context
5116 where J was used in the second set. We also count the number of such
5117 pending equivalences. If nonzero, the expressions really aren't the
5118 same. */
5119
5120 static int *same_regs;
5121
5122 static int num_same_regs;
5123
5124 /* Track any registers modified between the target of the first jump and
5125 the second jump. They never compare equal. */
5126
5127 static char *modified_regs;
5128
5129 /* Record if memory was modified. */
5130
5131 static int modified_mem;
5132
5133 /* Called via note_stores on each insn between the target of the first
5134 branch and the second branch. It marks any changed registers. */
5135
5136 static void
5137 mark_modified_reg (dest, x, data)
5138 rtx dest;
5139 rtx x ATTRIBUTE_UNUSED;
5140 void *data ATTRIBUTE_UNUSED;
5141 {
5142 int regno, i;
5143
5144 if (GET_CODE (dest) == SUBREG)
5145 dest = SUBREG_REG (dest);
5146
5147 if (GET_CODE (dest) == MEM)
5148 modified_mem = 1;
5149
5150 if (GET_CODE (dest) != REG)
5151 return;
5152
5153 regno = REGNO (dest);
5154 if (regno >= FIRST_PSEUDO_REGISTER)
5155 modified_regs[regno] = 1;
5156 else
5157 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
5158 modified_regs[regno + i] = 1;
5159 }
5160
5161 /* F is the first insn in the chain of insns. */
5162
5163 void
5164 thread_jumps (f, max_reg, flag_before_loop)
5165 rtx f;
5166 int max_reg;
5167 int flag_before_loop;
5168 {
5169 /* Basic algorithm is to find a conditional branch,
5170 the label it may branch to, and the branch after
5171 that label. If the two branches test the same condition,
5172 walk back from both branch paths until the insn patterns
5173 differ, or code labels are hit. If we make it back to
5174 the target of the first branch, then we know that the first branch
5175 will either always succeed or always fail depending on the relative
5176 senses of the two branches. So adjust the first branch accordingly
5177 in this case. */
5178
5179 rtx label, b1, b2, t1, t2;
5180 enum rtx_code code1, code2;
5181 rtx b1op0, b1op1, b2op0, b2op1;
5182 int changed = 1;
5183 int i;
5184 int *all_reset;
5185
5186 /* Allocate register tables and quick-reset table. */
5187 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
5188 same_regs = (int *) xmalloc (max_reg * sizeof (int));
5189 all_reset = (int *) xmalloc (max_reg * sizeof (int));
5190 for (i = 0; i < max_reg; i++)
5191 all_reset[i] = -1;
5192
5193 while (changed)
5194 {
5195 changed = 0;
5196
5197 for (b1 = f; b1; b1 = NEXT_INSN (b1))
5198 {
5199 /* Get to a candidate branch insn. */
5200 if (GET_CODE (b1) != JUMP_INSN
5201 || ! condjump_p (b1) || simplejump_p (b1)
5202 || JUMP_LABEL (b1) == 0)
5203 continue;
5204
5205 bzero (modified_regs, max_reg * sizeof (char));
5206 modified_mem = 0;
5207
5208 bcopy ((char *) all_reset, (char *) same_regs,
5209 max_reg * sizeof (int));
5210 num_same_regs = 0;
5211
5212 label = JUMP_LABEL (b1);
5213
5214 /* Look for a branch after the target. Record any registers and
5215 memory modified between the target and the branch. Stop when we
5216 get to a label since we can't know what was changed there. */
5217 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
5218 {
5219 if (GET_CODE (b2) == CODE_LABEL)
5220 break;
5221
5222 else if (GET_CODE (b2) == JUMP_INSN)
5223 {
5224 /* If this is an unconditional jump and is the only use of
5225 its target label, we can follow it. */
5226 if (simplejump_p (b2)
5227 && JUMP_LABEL (b2) != 0
5228 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
5229 {
5230 b2 = JUMP_LABEL (b2);
5231 continue;
5232 }
5233 else
5234 break;
5235 }
5236
5237 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
5238 continue;
5239
5240 if (GET_CODE (b2) == CALL_INSN)
5241 {
5242 modified_mem = 1;
5243 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5244 if (call_used_regs[i] && ! fixed_regs[i]
5245 && i != STACK_POINTER_REGNUM
5246 && i != FRAME_POINTER_REGNUM
5247 && i != HARD_FRAME_POINTER_REGNUM
5248 && i != ARG_POINTER_REGNUM)
5249 modified_regs[i] = 1;
5250 }
5251
5252 note_stores (PATTERN (b2), mark_modified_reg, NULL);
5253 }
5254
5255 /* Check the next candidate branch insn from the label
5256 of the first. */
5257 if (b2 == 0
5258 || GET_CODE (b2) != JUMP_INSN
5259 || b2 == b1
5260 || ! condjump_p (b2)
5261 || simplejump_p (b2))
5262 continue;
5263
5264 /* Get the comparison codes and operands, reversing the
5265 codes if appropriate. If we don't have comparison codes,
5266 we can't do anything. */
5267 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
5268 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
5269 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
5270 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
5271 code1 = reverse_condition (code1);
5272
5273 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
5274 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
5275 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
5276 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
5277 code2 = reverse_condition (code2);
5278
5279 /* If they test the same things and knowing that B1 branches
5280 tells us whether or not B2 branches, check if we
5281 can thread the branch. */
5282 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
5283 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
5284 && (comparison_dominates_p (code1, code2)
5285 || (comparison_dominates_p (code1, reverse_condition (code2))
5286 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
5287 0),
5288 b1))))
5289 {
5290 t1 = prev_nonnote_insn (b1);
5291 t2 = prev_nonnote_insn (b2);
5292
5293 while (t1 != 0 && t2 != 0)
5294 {
5295 if (t2 == label)
5296 {
5297 /* We have reached the target of the first branch.
5298 If there are no pending register equivalents,
5299 we know that this branch will either always
5300 succeed (if the senses of the two branches are
5301 the same) or always fail (if not). */
5302 rtx new_label;
5303
5304 if (num_same_regs != 0)
5305 break;
5306
5307 if (comparison_dominates_p (code1, code2))
5308 new_label = JUMP_LABEL (b2);
5309 else
5310 new_label = get_label_after (b2);
5311
5312 if (JUMP_LABEL (b1) != new_label)
5313 {
5314 rtx prev = PREV_INSN (new_label);
5315
5316 if (flag_before_loop
5317 && GET_CODE (prev) == NOTE
5318 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
5319 {
5320 /* Don't thread to the loop label. If a loop
5321 label is reused, loop optimization will
5322 be disabled for that loop. */
5323 new_label = gen_label_rtx ();
5324 emit_label_after (new_label, PREV_INSN (prev));
5325 }
5326 changed |= redirect_jump (b1, new_label);
5327 }
5328 break;
5329 }
5330
5331 /* If either of these is not a normal insn (it might be
5332 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
5333 have already been skipped above.) Similarly, fail
5334 if the insns are different. */
5335 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
5336 || recog_memoized (t1) != recog_memoized (t2)
5337 || ! rtx_equal_for_thread_p (PATTERN (t1),
5338 PATTERN (t2), t2))
5339 break;
5340
5341 t1 = prev_nonnote_insn (t1);
5342 t2 = prev_nonnote_insn (t2);
5343 }
5344 }
5345 }
5346 }
5347
5348 /* Clean up. */
5349 free (modified_regs);
5350 free (same_regs);
5351 free (all_reset);
5352 }
5353 \f
5354 /* This is like RTX_EQUAL_P except that it knows about our handling of
5355 possibly equivalent registers and knows to consider volatile and
5356 modified objects as not equal.
5357
5358 YINSN is the insn containing Y. */
5359
5360 int
5361 rtx_equal_for_thread_p (x, y, yinsn)
5362 rtx x, y;
5363 rtx yinsn;
5364 {
5365 register int i;
5366 register int j;
5367 register enum rtx_code code;
5368 register const char *fmt;
5369
5370 code = GET_CODE (x);
5371 /* Rtx's of different codes cannot be equal. */
5372 if (code != GET_CODE (y))
5373 return 0;
5374
5375 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
5376 (REG:SI x) and (REG:HI x) are NOT equivalent. */
5377
5378 if (GET_MODE (x) != GET_MODE (y))
5379 return 0;
5380
5381 /* For floating-point, consider everything unequal. This is a bit
5382 pessimistic, but this pass would only rarely do anything for FP
5383 anyway. */
5384 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
5385 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
5386 return 0;
5387
5388 /* For commutative operations, the RTX match if the operand match in any
5389 order. Also handle the simple binary and unary cases without a loop. */
5390 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
5391 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
5392 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
5393 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
5394 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
5395 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
5396 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
5397 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
5398 else if (GET_RTX_CLASS (code) == '1')
5399 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
5400
5401 /* Handle special-cases first. */
5402 switch (code)
5403 {
5404 case REG:
5405 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
5406 return 1;
5407
5408 /* If neither is user variable or hard register, check for possible
5409 equivalence. */
5410 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
5411 || REGNO (x) < FIRST_PSEUDO_REGISTER
5412 || REGNO (y) < FIRST_PSEUDO_REGISTER)
5413 return 0;
5414
5415 if (same_regs[REGNO (x)] == -1)
5416 {
5417 same_regs[REGNO (x)] = REGNO (y);
5418 num_same_regs++;
5419
5420 /* If this is the first time we are seeing a register on the `Y'
5421 side, see if it is the last use. If not, we can't thread the
5422 jump, so mark it as not equivalent. */
5423 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
5424 return 0;
5425
5426 return 1;
5427 }
5428 else
5429 return (same_regs[REGNO (x)] == REGNO (y));
5430
5431 break;
5432
5433 case MEM:
5434 /* If memory modified or either volatile, not equivalent.
5435 Else, check address. */
5436 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5437 return 0;
5438
5439 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
5440
5441 case ASM_INPUT:
5442 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5443 return 0;
5444
5445 break;
5446
5447 case SET:
5448 /* Cancel a pending `same_regs' if setting equivalenced registers.
5449 Then process source. */
5450 if (GET_CODE (SET_DEST (x)) == REG
5451 && GET_CODE (SET_DEST (y)) == REG)
5452 {
5453 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
5454 {
5455 same_regs[REGNO (SET_DEST (x))] = -1;
5456 num_same_regs--;
5457 }
5458 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
5459 return 0;
5460 }
5461 else
5462 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
5463 return 0;
5464
5465 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
5466
5467 case LABEL_REF:
5468 return XEXP (x, 0) == XEXP (y, 0);
5469
5470 case SYMBOL_REF:
5471 return XSTR (x, 0) == XSTR (y, 0);
5472
5473 default:
5474 break;
5475 }
5476
5477 if (x == y)
5478 return 1;
5479
5480 fmt = GET_RTX_FORMAT (code);
5481 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5482 {
5483 switch (fmt[i])
5484 {
5485 case 'w':
5486 if (XWINT (x, i) != XWINT (y, i))
5487 return 0;
5488 break;
5489
5490 case 'n':
5491 case 'i':
5492 if (XINT (x, i) != XINT (y, i))
5493 return 0;
5494 break;
5495
5496 case 'V':
5497 case 'E':
5498 /* Two vectors must have the same length. */
5499 if (XVECLEN (x, i) != XVECLEN (y, i))
5500 return 0;
5501
5502 /* And the corresponding elements must match. */
5503 for (j = 0; j < XVECLEN (x, i); j++)
5504 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
5505 XVECEXP (y, i, j), yinsn) == 0)
5506 return 0;
5507 break;
5508
5509 case 'e':
5510 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
5511 return 0;
5512 break;
5513
5514 case 'S':
5515 case 's':
5516 if (strcmp (XSTR (x, i), XSTR (y, i)))
5517 return 0;
5518 break;
5519
5520 case 'u':
5521 /* These are just backpointers, so they don't matter. */
5522 break;
5523
5524 case '0':
5525 case 't':
5526 break;
5527
5528 /* It is believed that rtx's at this level will never
5529 contain anything but integers and other rtx's,
5530 except for within LABEL_REFs and SYMBOL_REFs. */
5531 default:
5532 abort ();
5533 }
5534 }
5535 return 1;
5536 }
5537 \f
5538
5539 #if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
5540 /* Return the insn that NEW can be safely inserted in front of starting at
5541 the jump insn INSN. Return 0 if it is not safe to do this jump
5542 optimization. Note that NEW must contain a single set. */
5543
5544 static rtx
5545 find_insert_position (insn, new)
5546 rtx insn;
5547 rtx new;
5548 {
5549 int i;
5550 rtx prev;
5551
5552 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
5553 if (GET_CODE (PATTERN (new)) != PARALLEL)
5554 return insn;
5555
5556 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5557 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5558 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5559 insn))
5560 break;
5561
5562 if (i < 0)
5563 return insn;
5564
5565 /* There is a good chance that the previous insn PREV sets the thing
5566 being clobbered (often the CC in a hard reg). If PREV does not
5567 use what NEW sets, we can insert NEW before PREV. */
5568
5569 prev = prev_active_insn (insn);
5570 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5571 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5572 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5573 insn)
5574 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5575 prev))
5576 return 0;
5577
5578 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
5579 }
5580 #endif /* !HAVE_cc0 */