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defaults.h (ASM_OUTPUT_ALTERNATE_LABEL_NAME): Provide default.
[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
2437 && LABEL_NUSES (insn) == 0
2438 && LABEL_ALTERNATE_NAME (insn) == NULL)
2439 insn = delete_insn (insn);
2440 else
2441 {
2442 final = insn;
2443 insn = NEXT_INSN (insn);
2444 }
2445 }
2446
2447 return final;
2448 }
2449
2450 /* Delete various simple forms of moves which have no necessary
2451 side effect. */
2452
2453 static void
2454 delete_noop_moves (f)
2455 rtx f;
2456 {
2457 rtx insn, next;
2458
2459 for (insn = f; insn; )
2460 {
2461 next = NEXT_INSN (insn);
2462
2463 if (GET_CODE (insn) == INSN)
2464 {
2465 register rtx body = PATTERN (insn);
2466
2467 /* Combine stack_adjusts with following push_insns. */
2468 #ifdef PUSH_ROUNDING
2469 if (GET_CODE (body) == SET
2470 && SET_DEST (body) == stack_pointer_rtx
2471 && GET_CODE (SET_SRC (body)) == PLUS
2472 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
2473 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
2474 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
2475 {
2476 rtx p;
2477 rtx stack_adjust_insn = insn;
2478 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
2479 int total_pushed = 0;
2480 int pushes = 0;
2481
2482 /* Find all successive push insns. */
2483 p = insn;
2484 /* Don't convert more than three pushes;
2485 that starts adding too many displaced addresses
2486 and the whole thing starts becoming a losing
2487 proposition. */
2488 while (pushes < 3)
2489 {
2490 rtx pbody, dest;
2491 p = next_nonnote_insn (p);
2492 if (p == 0 || GET_CODE (p) != INSN)
2493 break;
2494 pbody = PATTERN (p);
2495 if (GET_CODE (pbody) != SET)
2496 break;
2497 dest = SET_DEST (pbody);
2498 /* Allow a no-op move between the adjust and the push. */
2499 if (GET_CODE (dest) == REG
2500 && GET_CODE (SET_SRC (pbody)) == REG
2501 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2502 continue;
2503 if (! (GET_CODE (dest) == MEM
2504 && GET_CODE (XEXP (dest, 0)) == POST_INC
2505 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2506 break;
2507 pushes++;
2508 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
2509 > stack_adjust_amount)
2510 break;
2511 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2512 }
2513
2514 /* Discard the amount pushed from the stack adjust;
2515 maybe eliminate it entirely. */
2516 if (total_pushed >= stack_adjust_amount)
2517 {
2518 delete_computation (stack_adjust_insn);
2519 total_pushed = stack_adjust_amount;
2520 }
2521 else
2522 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
2523 = GEN_INT (stack_adjust_amount - total_pushed);
2524
2525 /* Change the appropriate push insns to ordinary stores. */
2526 p = insn;
2527 while (total_pushed > 0)
2528 {
2529 rtx pbody, dest;
2530 p = next_nonnote_insn (p);
2531 if (GET_CODE (p) != INSN)
2532 break;
2533 pbody = PATTERN (p);
2534 if (GET_CODE (pbody) != SET)
2535 break;
2536 dest = SET_DEST (pbody);
2537 /* Allow a no-op move between the adjust and the push. */
2538 if (GET_CODE (dest) == REG
2539 && GET_CODE (SET_SRC (pbody)) == REG
2540 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2541 continue;
2542 if (! (GET_CODE (dest) == MEM
2543 && GET_CODE (XEXP (dest, 0)) == POST_INC
2544 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2545 break;
2546 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2547 /* If this push doesn't fully fit in the space
2548 of the stack adjust that we deleted,
2549 make another stack adjust here for what we
2550 didn't use up. There should be peepholes
2551 to recognize the resulting sequence of insns. */
2552 if (total_pushed < 0)
2553 {
2554 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
2555 GEN_INT (- total_pushed)),
2556 p);
2557 break;
2558 }
2559 XEXP (dest, 0)
2560 = plus_constant (stack_pointer_rtx, total_pushed);
2561 }
2562 }
2563 #endif
2564
2565 /* Detect and delete no-op move instructions
2566 resulting from not allocating a parameter in a register. */
2567
2568 if (GET_CODE (body) == SET
2569 && (SET_DEST (body) == SET_SRC (body)
2570 || (GET_CODE (SET_DEST (body)) == MEM
2571 && GET_CODE (SET_SRC (body)) == MEM
2572 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
2573 && ! (GET_CODE (SET_DEST (body)) == MEM
2574 && MEM_VOLATILE_P (SET_DEST (body)))
2575 && ! (GET_CODE (SET_SRC (body)) == MEM
2576 && MEM_VOLATILE_P (SET_SRC (body))))
2577 delete_computation (insn);
2578
2579 /* Detect and ignore no-op move instructions
2580 resulting from smart or fortuitous register allocation. */
2581
2582 else if (GET_CODE (body) == SET)
2583 {
2584 int sreg = true_regnum (SET_SRC (body));
2585 int dreg = true_regnum (SET_DEST (body));
2586
2587 if (sreg == dreg && sreg >= 0)
2588 delete_insn (insn);
2589 else if (sreg >= 0 && dreg >= 0)
2590 {
2591 rtx trial;
2592 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
2593 sreg, NULL_PTR, dreg,
2594 GET_MODE (SET_SRC (body)));
2595
2596 if (tem != 0
2597 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
2598 {
2599 /* DREG may have been the target of a REG_DEAD note in
2600 the insn which makes INSN redundant. If so, reorg
2601 would still think it is dead. So search for such a
2602 note and delete it if we find it. */
2603 if (! find_regno_note (insn, REG_UNUSED, dreg))
2604 for (trial = prev_nonnote_insn (insn);
2605 trial && GET_CODE (trial) != CODE_LABEL;
2606 trial = prev_nonnote_insn (trial))
2607 if (find_regno_note (trial, REG_DEAD, dreg))
2608 {
2609 remove_death (dreg, trial);
2610 break;
2611 }
2612
2613 /* Deleting insn could lose a death-note for SREG. */
2614 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
2615 {
2616 /* Change this into a USE so that we won't emit
2617 code for it, but still can keep the note. */
2618 PATTERN (insn)
2619 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
2620 INSN_CODE (insn) = -1;
2621 /* Remove all reg notes but the REG_DEAD one. */
2622 REG_NOTES (insn) = trial;
2623 XEXP (trial, 1) = NULL_RTX;
2624 }
2625 else
2626 delete_insn (insn);
2627 }
2628 }
2629 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
2630 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
2631 NULL_PTR, 0,
2632 GET_MODE (SET_DEST (body))))
2633 {
2634 /* This handles the case where we have two consecutive
2635 assignments of the same constant to pseudos that didn't
2636 get a hard reg. Each SET from the constant will be
2637 converted into a SET of the spill register and an
2638 output reload will be made following it. This produces
2639 two loads of the same constant into the same spill
2640 register. */
2641
2642 rtx in_insn = insn;
2643
2644 /* Look back for a death note for the first reg.
2645 If there is one, it is no longer accurate. */
2646 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
2647 {
2648 if ((GET_CODE (in_insn) == INSN
2649 || GET_CODE (in_insn) == JUMP_INSN)
2650 && find_regno_note (in_insn, REG_DEAD, dreg))
2651 {
2652 remove_death (dreg, in_insn);
2653 break;
2654 }
2655 in_insn = PREV_INSN (in_insn);
2656 }
2657
2658 /* Delete the second load of the value. */
2659 delete_insn (insn);
2660 }
2661 }
2662 else if (GET_CODE (body) == PARALLEL)
2663 {
2664 /* If each part is a set between two identical registers or
2665 a USE or CLOBBER, delete the insn. */
2666 int i, sreg, dreg;
2667 rtx tem;
2668
2669 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
2670 {
2671 tem = XVECEXP (body, 0, i);
2672 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
2673 continue;
2674
2675 if (GET_CODE (tem) != SET
2676 || (sreg = true_regnum (SET_SRC (tem))) < 0
2677 || (dreg = true_regnum (SET_DEST (tem))) < 0
2678 || dreg != sreg)
2679 break;
2680 }
2681
2682 if (i < 0)
2683 delete_insn (insn);
2684 }
2685 /* Also delete insns to store bit fields if they are no-ops. */
2686 /* Not worth the hair to detect this in the big-endian case. */
2687 else if (! BYTES_BIG_ENDIAN
2688 && GET_CODE (body) == SET
2689 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
2690 && XEXP (SET_DEST (body), 2) == const0_rtx
2691 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
2692 && ! (GET_CODE (SET_SRC (body)) == MEM
2693 && MEM_VOLATILE_P (SET_SRC (body))))
2694 delete_insn (insn);
2695 }
2696 insn = next;
2697 }
2698 }
2699
2700 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2701 If so indicate that this function can drop off the end by returning
2702 1, else return 0.
2703
2704 CHECK_DELETED indicates whether we must check if the note being
2705 searched for has the deleted flag set.
2706
2707 DELETE_FINAL_NOTE indicates whether we should delete the note
2708 if we find it. */
2709
2710 static int
2711 calculate_can_reach_end (last, check_deleted, delete_final_note)
2712 rtx last;
2713 int check_deleted;
2714 int delete_final_note;
2715 {
2716 rtx insn = last;
2717 int n_labels = 1;
2718
2719 while (insn != NULL_RTX)
2720 {
2721 int ok = 0;
2722
2723 /* One label can follow the end-note: the return label. */
2724 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2725 ok = 1;
2726 /* Ordinary insns can follow it if returning a structure. */
2727 else if (GET_CODE (insn) == INSN)
2728 ok = 1;
2729 /* If machine uses explicit RETURN insns, no epilogue,
2730 then one of them follows the note. */
2731 else if (GET_CODE (insn) == JUMP_INSN
2732 && GET_CODE (PATTERN (insn)) == RETURN)
2733 ok = 1;
2734 /* A barrier can follow the return insn. */
2735 else if (GET_CODE (insn) == BARRIER)
2736 ok = 1;
2737 /* Other kinds of notes can follow also. */
2738 else if (GET_CODE (insn) == NOTE
2739 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2740 ok = 1;
2741
2742 if (ok != 1)
2743 break;
2744
2745 insn = PREV_INSN (insn);
2746 }
2747
2748 /* See if we backed up to the appropriate type of note. */
2749 if (insn != NULL_RTX
2750 && GET_CODE (insn) == NOTE
2751 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
2752 && (check_deleted == 0
2753 || ! INSN_DELETED_P (insn)))
2754 {
2755 if (delete_final_note)
2756 delete_insn (insn);
2757 return 1;
2758 }
2759
2760 return 0;
2761 }
2762
2763 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2764 jump. Assume that this unconditional jump is to the exit test code. If
2765 the code is sufficiently simple, make a copy of it before INSN,
2766 followed by a jump to the exit of the loop. Then delete the unconditional
2767 jump after INSN.
2768
2769 Return 1 if we made the change, else 0.
2770
2771 This is only safe immediately after a regscan pass because it uses the
2772 values of regno_first_uid and regno_last_uid. */
2773
2774 static int
2775 duplicate_loop_exit_test (loop_start)
2776 rtx loop_start;
2777 {
2778 rtx insn, set, reg, p, link;
2779 rtx copy = 0, first_copy = 0;
2780 int num_insns = 0;
2781 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2782 rtx lastexit;
2783 int max_reg = max_reg_num ();
2784 rtx *reg_map = 0;
2785
2786 /* Scan the exit code. We do not perform this optimization if any insn:
2787
2788 is a CALL_INSN
2789 is a CODE_LABEL
2790 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2791 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2792 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2793 is not valid.
2794
2795 We also do not do this if we find an insn with ASM_OPERANDS. While
2796 this restriction should not be necessary, copying an insn with
2797 ASM_OPERANDS can confuse asm_noperands in some cases.
2798
2799 Also, don't do this if the exit code is more than 20 insns. */
2800
2801 for (insn = exitcode;
2802 insn
2803 && ! (GET_CODE (insn) == NOTE
2804 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2805 insn = NEXT_INSN (insn))
2806 {
2807 switch (GET_CODE (insn))
2808 {
2809 case CODE_LABEL:
2810 case CALL_INSN:
2811 return 0;
2812 case NOTE:
2813 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2814 a jump immediately after the loop start that branches outside
2815 the loop but within an outer loop, near the exit test.
2816 If we copied this exit test and created a phony
2817 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2818 before the exit test look like these could be safely moved
2819 out of the loop even if they actually may be never executed.
2820 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2821
2822 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2823 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2824 return 0;
2825
2826 if (optimize < 2
2827 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2828 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
2829 /* If we were to duplicate this code, we would not move
2830 the BLOCK notes, and so debugging the moved code would
2831 be difficult. Thus, we only move the code with -O2 or
2832 higher. */
2833 return 0;
2834
2835 break;
2836 case JUMP_INSN:
2837 case INSN:
2838 /* The code below would grossly mishandle REG_WAS_0 notes,
2839 so get rid of them here. */
2840 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
2841 remove_note (insn, p);
2842 if (++num_insns > 20
2843 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2844 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2845 return 0;
2846 break;
2847 default:
2848 break;
2849 }
2850 }
2851
2852 /* Unless INSN is zero, we can do the optimization. */
2853 if (insn == 0)
2854 return 0;
2855
2856 lastexit = insn;
2857
2858 /* See if any insn sets a register only used in the loop exit code and
2859 not a user variable. If so, replace it with a new register. */
2860 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2861 if (GET_CODE (insn) == INSN
2862 && (set = single_set (insn)) != 0
2863 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2864 || (GET_CODE (reg) == SUBREG
2865 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2866 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2867 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2868 {
2869 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2870 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2871 break;
2872
2873 if (p != lastexit)
2874 {
2875 /* We can do the replacement. Allocate reg_map if this is the
2876 first replacement we found. */
2877 if (reg_map == 0)
2878 reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
2879
2880 REG_LOOP_TEST_P (reg) = 1;
2881
2882 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2883 }
2884 }
2885
2886 /* Now copy each insn. */
2887 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2888 {
2889 switch (GET_CODE (insn))
2890 {
2891 case BARRIER:
2892 copy = emit_barrier_before (loop_start);
2893 break;
2894 case NOTE:
2895 /* Only copy line-number notes. */
2896 if (NOTE_LINE_NUMBER (insn) >= 0)
2897 {
2898 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2899 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2900 }
2901 break;
2902
2903 case INSN:
2904 copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
2905 if (reg_map)
2906 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2907
2908 mark_jump_label (PATTERN (copy), copy, 0);
2909
2910 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2911 make them. */
2912 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2913 if (REG_NOTE_KIND (link) != REG_LABEL)
2914 REG_NOTES (copy)
2915 = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2916 XEXP (link, 0),
2917 REG_NOTES (copy)));
2918 if (reg_map && REG_NOTES (copy))
2919 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2920 break;
2921
2922 case JUMP_INSN:
2923 copy = emit_jump_insn_before (copy_insn (PATTERN (insn)), loop_start);
2924 if (reg_map)
2925 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2926 mark_jump_label (PATTERN (copy), copy, 0);
2927 if (REG_NOTES (insn))
2928 {
2929 REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
2930 if (reg_map)
2931 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2932 }
2933
2934 /* If this is a simple jump, add it to the jump chain. */
2935
2936 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2937 && simplejump_p (copy))
2938 {
2939 jump_chain[INSN_UID (copy)]
2940 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2941 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2942 }
2943 break;
2944
2945 default:
2946 abort ();
2947 }
2948
2949 /* Record the first insn we copied. We need it so that we can
2950 scan the copied insns for new pseudo registers. */
2951 if (! first_copy)
2952 first_copy = copy;
2953 }
2954
2955 /* Now clean up by emitting a jump to the end label and deleting the jump
2956 at the start of the loop. */
2957 if (! copy || GET_CODE (copy) != BARRIER)
2958 {
2959 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2960 loop_start);
2961
2962 /* Record the first insn we copied. We need it so that we can
2963 scan the copied insns for new pseudo registers. This may not
2964 be strictly necessary since we should have copied at least one
2965 insn above. But I am going to be safe. */
2966 if (! first_copy)
2967 first_copy = copy;
2968
2969 mark_jump_label (PATTERN (copy), copy, 0);
2970 if (INSN_UID (copy) < max_jump_chain
2971 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2972 {
2973 jump_chain[INSN_UID (copy)]
2974 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2975 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2976 }
2977 emit_barrier_before (loop_start);
2978 }
2979
2980 /* Now scan from the first insn we copied to the last insn we copied
2981 (copy) for new pseudo registers. Do this after the code to jump to
2982 the end label since that might create a new pseudo too. */
2983 reg_scan_update (first_copy, copy, max_reg);
2984
2985 /* Mark the exit code as the virtual top of the converted loop. */
2986 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2987
2988 delete_insn (next_nonnote_insn (loop_start));
2989
2990 /* Clean up. */
2991 if (reg_map)
2992 free (reg_map);
2993
2994 return 1;
2995 }
2996 \f
2997 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2998 loop-end notes between START and END out before START. Assume that
2999 END is not such a note. START may be such a note. Returns the value
3000 of the new starting insn, which may be different if the original start
3001 was such a note. */
3002
3003 rtx
3004 squeeze_notes (start, end)
3005 rtx start, end;
3006 {
3007 rtx insn;
3008 rtx next;
3009
3010 for (insn = start; insn != end; insn = next)
3011 {
3012 next = NEXT_INSN (insn);
3013 if (GET_CODE (insn) == NOTE
3014 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
3015 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
3016 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
3017 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
3018 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
3019 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
3020 {
3021 if (insn == start)
3022 start = next;
3023 else
3024 {
3025 rtx prev = PREV_INSN (insn);
3026 PREV_INSN (insn) = PREV_INSN (start);
3027 NEXT_INSN (insn) = start;
3028 NEXT_INSN (PREV_INSN (insn)) = insn;
3029 PREV_INSN (NEXT_INSN (insn)) = insn;
3030 NEXT_INSN (prev) = next;
3031 PREV_INSN (next) = prev;
3032 }
3033 }
3034 }
3035
3036 return start;
3037 }
3038 \f
3039 /* Compare the instructions before insn E1 with those before E2
3040 to find an opportunity for cross jumping.
3041 (This means detecting identical sequences of insns followed by
3042 jumps to the same place, or followed by a label and a jump
3043 to that label, and replacing one with a jump to the other.)
3044
3045 Assume E1 is a jump that jumps to label E2
3046 (that is not always true but it might as well be).
3047 Find the longest possible equivalent sequences
3048 and store the first insns of those sequences into *F1 and *F2.
3049 Store zero there if no equivalent preceding instructions are found.
3050
3051 We give up if we find a label in stream 1.
3052 Actually we could transfer that label into stream 2. */
3053
3054 static void
3055 find_cross_jump (e1, e2, minimum, f1, f2)
3056 rtx e1, e2;
3057 int minimum;
3058 rtx *f1, *f2;
3059 {
3060 register rtx i1 = e1, i2 = e2;
3061 register rtx p1, p2;
3062 int lose = 0;
3063
3064 rtx last1 = 0, last2 = 0;
3065 rtx afterlast1 = 0, afterlast2 = 0;
3066
3067 *f1 = 0;
3068 *f2 = 0;
3069
3070 while (1)
3071 {
3072 i1 = prev_nonnote_insn (i1);
3073
3074 i2 = PREV_INSN (i2);
3075 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
3076 i2 = PREV_INSN (i2);
3077
3078 if (i1 == 0)
3079 break;
3080
3081 /* Don't allow the range of insns preceding E1 or E2
3082 to include the other (E2 or E1). */
3083 if (i2 == e1 || i1 == e2)
3084 break;
3085
3086 /* If we will get to this code by jumping, those jumps will be
3087 tensioned to go directly to the new label (before I2),
3088 so this cross-jumping won't cost extra. So reduce the minimum. */
3089 if (GET_CODE (i1) == CODE_LABEL)
3090 {
3091 --minimum;
3092 break;
3093 }
3094
3095 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
3096 break;
3097
3098 /* Avoid moving insns across EH regions if either of the insns
3099 can throw. */
3100 if (flag_exceptions
3101 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
3102 && !in_same_eh_region (i1, i2))
3103 break;
3104
3105 p1 = PATTERN (i1);
3106 p2 = PATTERN (i2);
3107
3108 /* If this is a CALL_INSN, compare register usage information.
3109 If we don't check this on stack register machines, the two
3110 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3111 numbers of stack registers in the same basic block.
3112 If we don't check this on machines with delay slots, a delay slot may
3113 be filled that clobbers a parameter expected by the subroutine.
3114
3115 ??? We take the simple route for now and assume that if they're
3116 equal, they were constructed identically. */
3117
3118 if (GET_CODE (i1) == CALL_INSN
3119 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
3120 CALL_INSN_FUNCTION_USAGE (i2)))
3121 lose = 1;
3122
3123 #ifdef STACK_REGS
3124 /* If cross_jump_death_matters is not 0, the insn's mode
3125 indicates whether or not the insn contains any stack-like
3126 regs. */
3127
3128 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
3129 {
3130 /* If register stack conversion has already been done, then
3131 death notes must also be compared before it is certain that
3132 the two instruction streams match. */
3133
3134 rtx note;
3135 HARD_REG_SET i1_regset, i2_regset;
3136
3137 CLEAR_HARD_REG_SET (i1_regset);
3138 CLEAR_HARD_REG_SET (i2_regset);
3139
3140 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
3141 if (REG_NOTE_KIND (note) == REG_DEAD
3142 && STACK_REG_P (XEXP (note, 0)))
3143 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
3144
3145 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
3146 if (REG_NOTE_KIND (note) == REG_DEAD
3147 && STACK_REG_P (XEXP (note, 0)))
3148 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
3149
3150 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
3151
3152 lose = 1;
3153
3154 done:
3155 ;
3156 }
3157 #endif
3158
3159 /* Don't allow old-style asm or volatile extended asms to be accepted
3160 for cross jumping purposes. It is conceptually correct to allow
3161 them, since cross-jumping preserves the dynamic instruction order
3162 even though it is changing the static instruction order. However,
3163 if an asm is being used to emit an assembler pseudo-op, such as
3164 the MIPS `.set reorder' pseudo-op, then the static instruction order
3165 matters and it must be preserved. */
3166 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
3167 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
3168 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
3169 lose = 1;
3170
3171 if (lose || GET_CODE (p1) != GET_CODE (p2)
3172 || ! rtx_renumbered_equal_p (p1, p2))
3173 {
3174 /* The following code helps take care of G++ cleanups. */
3175 rtx equiv1;
3176 rtx equiv2;
3177
3178 if (!lose && GET_CODE (p1) == GET_CODE (p2)
3179 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
3180 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
3181 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
3182 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
3183 /* If the equivalences are not to a constant, they may
3184 reference pseudos that no longer exist, so we can't
3185 use them. */
3186 && CONSTANT_P (XEXP (equiv1, 0))
3187 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
3188 {
3189 rtx s1 = single_set (i1);
3190 rtx s2 = single_set (i2);
3191 if (s1 != 0 && s2 != 0
3192 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
3193 {
3194 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
3195 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
3196 if (! rtx_renumbered_equal_p (p1, p2))
3197 cancel_changes (0);
3198 else if (apply_change_group ())
3199 goto win;
3200 }
3201 }
3202
3203 /* Insns fail to match; cross jumping is limited to the following
3204 insns. */
3205
3206 #ifdef HAVE_cc0
3207 /* Don't allow the insn after a compare to be shared by
3208 cross-jumping unless the compare is also shared.
3209 Here, if either of these non-matching insns is a compare,
3210 exclude the following insn from possible cross-jumping. */
3211 if (sets_cc0_p (p1) || sets_cc0_p (p2))
3212 last1 = afterlast1, last2 = afterlast2, ++minimum;
3213 #endif
3214
3215 /* If cross-jumping here will feed a jump-around-jump
3216 optimization, this jump won't cost extra, so reduce
3217 the minimum. */
3218 if (GET_CODE (i1) == JUMP_INSN
3219 && JUMP_LABEL (i1)
3220 && prev_real_insn (JUMP_LABEL (i1)) == e1)
3221 --minimum;
3222 break;
3223 }
3224
3225 win:
3226 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
3227 {
3228 /* Ok, this insn is potentially includable in a cross-jump here. */
3229 afterlast1 = last1, afterlast2 = last2;
3230 last1 = i1, last2 = i2, --minimum;
3231 }
3232 }
3233
3234 if (minimum <= 0 && last1 != 0 && last1 != e1)
3235 *f1 = last1, *f2 = last2;
3236 }
3237
3238 static void
3239 do_cross_jump (insn, newjpos, newlpos)
3240 rtx insn, newjpos, newlpos;
3241 {
3242 /* Find an existing label at this point
3243 or make a new one if there is none. */
3244 register rtx label = get_label_before (newlpos);
3245
3246 /* Make the same jump insn jump to the new point. */
3247 if (GET_CODE (PATTERN (insn)) == RETURN)
3248 {
3249 /* Remove from jump chain of returns. */
3250 delete_from_jump_chain (insn);
3251 /* Change the insn. */
3252 PATTERN (insn) = gen_jump (label);
3253 INSN_CODE (insn) = -1;
3254 JUMP_LABEL (insn) = label;
3255 LABEL_NUSES (label)++;
3256 /* Add to new the jump chain. */
3257 if (INSN_UID (label) < max_jump_chain
3258 && INSN_UID (insn) < max_jump_chain)
3259 {
3260 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
3261 jump_chain[INSN_UID (label)] = insn;
3262 }
3263 }
3264 else
3265 redirect_jump (insn, label);
3266
3267 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
3268 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
3269 the NEWJPOS stream. */
3270
3271 while (newjpos != insn)
3272 {
3273 rtx lnote;
3274
3275 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
3276 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
3277 || REG_NOTE_KIND (lnote) == REG_EQUIV)
3278 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
3279 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
3280 remove_note (newlpos, lnote);
3281
3282 delete_insn (newjpos);
3283 newjpos = next_real_insn (newjpos);
3284 newlpos = next_real_insn (newlpos);
3285 }
3286 }
3287 \f
3288 /* Return the label before INSN, or put a new label there. */
3289
3290 rtx
3291 get_label_before (insn)
3292 rtx insn;
3293 {
3294 rtx label;
3295
3296 /* Find an existing label at this point
3297 or make a new one if there is none. */
3298 label = prev_nonnote_insn (insn);
3299
3300 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3301 {
3302 rtx prev = PREV_INSN (insn);
3303
3304 label = gen_label_rtx ();
3305 emit_label_after (label, prev);
3306 LABEL_NUSES (label) = 0;
3307 }
3308 return label;
3309 }
3310
3311 /* Return the label after INSN, or put a new label there. */
3312
3313 rtx
3314 get_label_after (insn)
3315 rtx insn;
3316 {
3317 rtx label;
3318
3319 /* Find an existing label at this point
3320 or make a new one if there is none. */
3321 label = next_nonnote_insn (insn);
3322
3323 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3324 {
3325 label = gen_label_rtx ();
3326 emit_label_after (label, insn);
3327 LABEL_NUSES (label) = 0;
3328 }
3329 return label;
3330 }
3331 \f
3332 /* Return 1 if INSN is a jump that jumps to right after TARGET
3333 only on the condition that TARGET itself would drop through.
3334 Assumes that TARGET is a conditional jump. */
3335
3336 static int
3337 jump_back_p (insn, target)
3338 rtx insn, target;
3339 {
3340 rtx cinsn, ctarget;
3341 enum rtx_code codei, codet;
3342
3343 if (simplejump_p (insn) || ! condjump_p (insn)
3344 || simplejump_p (target)
3345 || target != prev_real_insn (JUMP_LABEL (insn)))
3346 return 0;
3347
3348 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
3349 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
3350
3351 codei = GET_CODE (cinsn);
3352 codet = GET_CODE (ctarget);
3353
3354 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
3355 {
3356 if (! can_reverse_comparison_p (cinsn, insn))
3357 return 0;
3358 codei = reverse_condition (codei);
3359 }
3360
3361 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
3362 {
3363 if (! can_reverse_comparison_p (ctarget, target))
3364 return 0;
3365 codet = reverse_condition (codet);
3366 }
3367
3368 return (codei == codet
3369 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
3370 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
3371 }
3372 \f
3373 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3374 return non-zero if it is safe to reverse this comparison. It is if our
3375 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3376 this is known to be an integer comparison. */
3377
3378 int
3379 can_reverse_comparison_p (comparison, insn)
3380 rtx comparison;
3381 rtx insn;
3382 {
3383 rtx arg0;
3384
3385 /* If this is not actually a comparison, we can't reverse it. */
3386 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
3387 return 0;
3388
3389 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3390 /* If this is an NE comparison, it is safe to reverse it to an EQ
3391 comparison and vice versa, even for floating point. If no operands
3392 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3393 always false and NE is always true, so the reversal is also valid. */
3394 || flag_fast_math
3395 || GET_CODE (comparison) == NE
3396 || GET_CODE (comparison) == EQ)
3397 return 1;
3398
3399 arg0 = XEXP (comparison, 0);
3400
3401 /* Make sure ARG0 is one of the actual objects being compared. If we
3402 can't do this, we can't be sure the comparison can be reversed.
3403
3404 Handle cc0 and a MODE_CC register. */
3405 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
3406 #ifdef HAVE_cc0
3407 || arg0 == cc0_rtx
3408 #endif
3409 )
3410 {
3411 rtx prev = prev_nonnote_insn (insn);
3412 rtx set;
3413
3414 /* First see if the condition code mode alone if enough to say we can
3415 reverse the condition. If not, then search backwards for a set of
3416 ARG0. We do not need to check for an insn clobbering it since valid
3417 code will contain set a set with no intervening clobber. But
3418 stop when we reach a label. */
3419 #ifdef REVERSIBLE_CC_MODE
3420 if (GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC
3421 && REVERSIBLE_CC_MODE (GET_MODE (arg0)))
3422 return 1;
3423 #endif
3424
3425 for (prev = prev_nonnote_insn (insn);
3426 prev != 0 && GET_CODE (prev) != CODE_LABEL;
3427 prev = prev_nonnote_insn (prev))
3428 if ((set = single_set (prev)) != 0
3429 && rtx_equal_p (SET_DEST (set), arg0))
3430 {
3431 arg0 = SET_SRC (set);
3432
3433 if (GET_CODE (arg0) == COMPARE)
3434 arg0 = XEXP (arg0, 0);
3435 break;
3436 }
3437 }
3438
3439 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3440 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3441 return (GET_CODE (arg0) == CONST_INT
3442 || (GET_MODE (arg0) != VOIDmode
3443 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
3444 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
3445 }
3446
3447 /* Given an rtx-code for a comparison, return the code
3448 for the negated comparison.
3449 WATCH OUT! reverse_condition is not safe to use on a jump
3450 that might be acting on the results of an IEEE floating point comparison,
3451 because of the special treatment of non-signaling nans in comparisons.
3452 Use can_reverse_comparison_p to be sure. */
3453
3454 enum rtx_code
3455 reverse_condition (code)
3456 enum rtx_code code;
3457 {
3458 switch (code)
3459 {
3460 case EQ:
3461 return NE;
3462
3463 case NE:
3464 return EQ;
3465
3466 case GT:
3467 return LE;
3468
3469 case GE:
3470 return LT;
3471
3472 case LT:
3473 return GE;
3474
3475 case LE:
3476 return GT;
3477
3478 case GTU:
3479 return LEU;
3480
3481 case GEU:
3482 return LTU;
3483
3484 case LTU:
3485 return GEU;
3486
3487 case LEU:
3488 return GTU;
3489
3490 default:
3491 abort ();
3492 return UNKNOWN;
3493 }
3494 }
3495
3496 /* Similar, but return the code when two operands of a comparison are swapped.
3497 This IS safe for IEEE floating-point. */
3498
3499 enum rtx_code
3500 swap_condition (code)
3501 enum rtx_code code;
3502 {
3503 switch (code)
3504 {
3505 case EQ:
3506 case NE:
3507 return code;
3508
3509 case GT:
3510 return LT;
3511
3512 case GE:
3513 return LE;
3514
3515 case LT:
3516 return GT;
3517
3518 case LE:
3519 return GE;
3520
3521 case GTU:
3522 return LTU;
3523
3524 case GEU:
3525 return LEU;
3526
3527 case LTU:
3528 return GTU;
3529
3530 case LEU:
3531 return GEU;
3532
3533 default:
3534 abort ();
3535 return UNKNOWN;
3536 }
3537 }
3538
3539 /* Given a comparison CODE, return the corresponding unsigned comparison.
3540 If CODE is an equality comparison or already an unsigned comparison,
3541 CODE is returned. */
3542
3543 enum rtx_code
3544 unsigned_condition (code)
3545 enum rtx_code code;
3546 {
3547 switch (code)
3548 {
3549 case EQ:
3550 case NE:
3551 case GTU:
3552 case GEU:
3553 case LTU:
3554 case LEU:
3555 return code;
3556
3557 case GT:
3558 return GTU;
3559
3560 case GE:
3561 return GEU;
3562
3563 case LT:
3564 return LTU;
3565
3566 case LE:
3567 return LEU;
3568
3569 default:
3570 abort ();
3571 }
3572 }
3573
3574 /* Similarly, return the signed version of a comparison. */
3575
3576 enum rtx_code
3577 signed_condition (code)
3578 enum rtx_code code;
3579 {
3580 switch (code)
3581 {
3582 case EQ:
3583 case NE:
3584 case GT:
3585 case GE:
3586 case LT:
3587 case LE:
3588 return code;
3589
3590 case GTU:
3591 return GT;
3592
3593 case GEU:
3594 return GE;
3595
3596 case LTU:
3597 return LT;
3598
3599 case LEU:
3600 return LE;
3601
3602 default:
3603 abort ();
3604 }
3605 }
3606 \f
3607 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3608 truth of CODE1 implies the truth of CODE2. */
3609
3610 int
3611 comparison_dominates_p (code1, code2)
3612 enum rtx_code code1, code2;
3613 {
3614 if (code1 == code2)
3615 return 1;
3616
3617 switch (code1)
3618 {
3619 case EQ:
3620 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3621 return 1;
3622 break;
3623
3624 case LT:
3625 if (code2 == LE || code2 == NE)
3626 return 1;
3627 break;
3628
3629 case GT:
3630 if (code2 == GE || code2 == NE)
3631 return 1;
3632 break;
3633
3634 case LTU:
3635 if (code2 == LEU || code2 == NE)
3636 return 1;
3637 break;
3638
3639 case GTU:
3640 if (code2 == GEU || code2 == NE)
3641 return 1;
3642 break;
3643
3644 default:
3645 break;
3646 }
3647
3648 return 0;
3649 }
3650 \f
3651 /* Return 1 if INSN is an unconditional jump and nothing else. */
3652
3653 int
3654 simplejump_p (insn)
3655 rtx insn;
3656 {
3657 return (GET_CODE (insn) == JUMP_INSN
3658 && GET_CODE (PATTERN (insn)) == SET
3659 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3660 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3661 }
3662
3663 /* Return nonzero if INSN is a (possibly) conditional jump
3664 and nothing more. */
3665
3666 int
3667 condjump_p (insn)
3668 rtx insn;
3669 {
3670 register rtx x = PATTERN (insn);
3671
3672 if (GET_CODE (x) != SET
3673 || GET_CODE (SET_DEST (x)) != PC)
3674 return 0;
3675
3676 x = SET_SRC (x);
3677 if (GET_CODE (x) == LABEL_REF)
3678 return 1;
3679 else return (GET_CODE (x) == IF_THEN_ELSE
3680 && ((GET_CODE (XEXP (x, 2)) == PC
3681 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
3682 || GET_CODE (XEXP (x, 1)) == RETURN))
3683 || (GET_CODE (XEXP (x, 1)) == PC
3684 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
3685 || GET_CODE (XEXP (x, 2)) == RETURN))));
3686
3687 return 0;
3688 }
3689
3690 /* Return nonzero if INSN is a (possibly) conditional jump inside a
3691 PARALLEL. */
3692
3693 int
3694 condjump_in_parallel_p (insn)
3695 rtx insn;
3696 {
3697 register rtx x = PATTERN (insn);
3698
3699 if (GET_CODE (x) != PARALLEL)
3700 return 0;
3701 else
3702 x = XVECEXP (x, 0, 0);
3703
3704 if (GET_CODE (x) != SET)
3705 return 0;
3706 if (GET_CODE (SET_DEST (x)) != PC)
3707 return 0;
3708 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3709 return 1;
3710 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3711 return 0;
3712 if (XEXP (SET_SRC (x), 2) == pc_rtx
3713 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3714 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3715 return 1;
3716 if (XEXP (SET_SRC (x), 1) == pc_rtx
3717 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3718 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3719 return 1;
3720 return 0;
3721 }
3722
3723 /* Return the label of a conditional jump. */
3724
3725 rtx
3726 condjump_label (insn)
3727 rtx insn;
3728 {
3729 register rtx x = PATTERN (insn);
3730
3731 if (GET_CODE (x) == PARALLEL)
3732 x = XVECEXP (x, 0, 0);
3733 if (GET_CODE (x) != SET)
3734 return NULL_RTX;
3735 if (GET_CODE (SET_DEST (x)) != PC)
3736 return NULL_RTX;
3737 x = SET_SRC (x);
3738 if (GET_CODE (x) == LABEL_REF)
3739 return x;
3740 if (GET_CODE (x) != IF_THEN_ELSE)
3741 return NULL_RTX;
3742 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
3743 return XEXP (x, 1);
3744 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
3745 return XEXP (x, 2);
3746 return NULL_RTX;
3747 }
3748
3749 /* Return true if INSN is a (possibly conditional) return insn. */
3750
3751 static int
3752 returnjump_p_1 (loc, data)
3753 rtx *loc;
3754 void *data ATTRIBUTE_UNUSED;
3755 {
3756 rtx x = *loc;
3757 return GET_CODE (x) == RETURN;
3758 }
3759
3760 int
3761 returnjump_p (insn)
3762 rtx insn;
3763 {
3764 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
3765 }
3766
3767 /* Return true if INSN is a jump that only transfers control and
3768 nothing more. */
3769
3770 int
3771 onlyjump_p (insn)
3772 rtx insn;
3773 {
3774 rtx set;
3775
3776 if (GET_CODE (insn) != JUMP_INSN)
3777 return 0;
3778
3779 set = single_set (insn);
3780 if (set == NULL)
3781 return 0;
3782 if (GET_CODE (SET_DEST (set)) != PC)
3783 return 0;
3784 if (side_effects_p (SET_SRC (set)))
3785 return 0;
3786
3787 return 1;
3788 }
3789
3790 #ifdef HAVE_cc0
3791
3792 /* Return 1 if X is an RTX that does nothing but set the condition codes
3793 and CLOBBER or USE registers.
3794 Return -1 if X does explicitly set the condition codes,
3795 but also does other things. */
3796
3797 int
3798 sets_cc0_p (x)
3799 rtx x ATTRIBUTE_UNUSED;
3800 {
3801 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3802 return 1;
3803 if (GET_CODE (x) == PARALLEL)
3804 {
3805 int i;
3806 int sets_cc0 = 0;
3807 int other_things = 0;
3808 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3809 {
3810 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3811 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3812 sets_cc0 = 1;
3813 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3814 other_things = 1;
3815 }
3816 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3817 }
3818 return 0;
3819 }
3820 #endif
3821 \f
3822 /* Follow any unconditional jump at LABEL;
3823 return the ultimate label reached by any such chain of jumps.
3824 If LABEL is not followed by a jump, return LABEL.
3825 If the chain loops or we can't find end, return LABEL,
3826 since that tells caller to avoid changing the insn.
3827
3828 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3829 a USE or CLOBBER. */
3830
3831 rtx
3832 follow_jumps (label)
3833 rtx label;
3834 {
3835 register rtx insn;
3836 register rtx next;
3837 register rtx value = label;
3838 register int depth;
3839
3840 for (depth = 0;
3841 (depth < 10
3842 && (insn = next_active_insn (value)) != 0
3843 && GET_CODE (insn) == JUMP_INSN
3844 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3845 || GET_CODE (PATTERN (insn)) == RETURN)
3846 && (next = NEXT_INSN (insn))
3847 && GET_CODE (next) == BARRIER);
3848 depth++)
3849 {
3850 /* Don't chain through the insn that jumps into a loop
3851 from outside the loop,
3852 since that would create multiple loop entry jumps
3853 and prevent loop optimization. */
3854 rtx tem;
3855 if (!reload_completed)
3856 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3857 if (GET_CODE (tem) == NOTE
3858 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3859 /* ??? Optional. Disables some optimizations, but makes
3860 gcov output more accurate with -O. */
3861 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3862 return value;
3863
3864 /* If we have found a cycle, make the insn jump to itself. */
3865 if (JUMP_LABEL (insn) == label)
3866 return label;
3867
3868 tem = next_active_insn (JUMP_LABEL (insn));
3869 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3870 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3871 break;
3872
3873 value = JUMP_LABEL (insn);
3874 }
3875 if (depth == 10)
3876 return label;
3877 return value;
3878 }
3879
3880 /* Assuming that field IDX of X is a vector of label_refs,
3881 replace each of them by the ultimate label reached by it.
3882 Return nonzero if a change is made.
3883 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3884
3885 static int
3886 tension_vector_labels (x, idx)
3887 register rtx x;
3888 register int idx;
3889 {
3890 int changed = 0;
3891 register int i;
3892 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3893 {
3894 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3895 register rtx nlabel = follow_jumps (olabel);
3896 if (nlabel && nlabel != olabel)
3897 {
3898 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3899 ++LABEL_NUSES (nlabel);
3900 if (--LABEL_NUSES (olabel) == 0)
3901 delete_insn (olabel);
3902 changed = 1;
3903 }
3904 }
3905 return changed;
3906 }
3907 \f
3908 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3909 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3910 in INSN, then store one of them in JUMP_LABEL (INSN).
3911 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3912 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3913 Also, when there are consecutive labels, canonicalize on the last of them.
3914
3915 Note that two labels separated by a loop-beginning note
3916 must be kept distinct if we have not yet done loop-optimization,
3917 because the gap between them is where loop-optimize
3918 will want to move invariant code to. CROSS_JUMP tells us
3919 that loop-optimization is done with.
3920
3921 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3922 two labels distinct if they are separated by only USE or CLOBBER insns. */
3923
3924 static void
3925 mark_jump_label (x, insn, cross_jump)
3926 register rtx x;
3927 rtx insn;
3928 int cross_jump;
3929 {
3930 register RTX_CODE code = GET_CODE (x);
3931 register int i;
3932 register const char *fmt;
3933
3934 switch (code)
3935 {
3936 case PC:
3937 case CC0:
3938 case REG:
3939 case SUBREG:
3940 case CONST_INT:
3941 case SYMBOL_REF:
3942 case CONST_DOUBLE:
3943 case CLOBBER:
3944 case CALL:
3945 return;
3946
3947 case MEM:
3948 /* If this is a constant-pool reference, see if it is a label. */
3949 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3950 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3951 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3952 break;
3953
3954 case LABEL_REF:
3955 {
3956 rtx label = XEXP (x, 0);
3957 rtx olabel = label;
3958 rtx note;
3959 rtx next;
3960
3961 if (GET_CODE (label) != CODE_LABEL)
3962 abort ();
3963
3964 /* Ignore references to labels of containing functions. */
3965 if (LABEL_REF_NONLOCAL_P (x))
3966 break;
3967
3968 /* If there are other labels following this one,
3969 replace it with the last of the consecutive labels. */
3970 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3971 {
3972 if (GET_CODE (next) == CODE_LABEL)
3973 label = next;
3974 else if (cross_jump && GET_CODE (next) == INSN
3975 && (GET_CODE (PATTERN (next)) == USE
3976 || GET_CODE (PATTERN (next)) == CLOBBER))
3977 continue;
3978 else if (GET_CODE (next) != NOTE)
3979 break;
3980 else if (! cross_jump
3981 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3982 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3983 /* ??? Optional. Disables some optimizations, but
3984 makes gcov output more accurate with -O. */
3985 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3986 break;
3987 }
3988
3989 XEXP (x, 0) = label;
3990 if (! insn || ! INSN_DELETED_P (insn))
3991 ++LABEL_NUSES (label);
3992
3993 if (insn)
3994 {
3995 if (GET_CODE (insn) == JUMP_INSN)
3996 JUMP_LABEL (insn) = label;
3997
3998 /* If we've changed OLABEL and we had a REG_LABEL note
3999 for it, update it as well. */
4000 else if (label != olabel
4001 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
4002 XEXP (note, 0) = label;
4003
4004 /* Otherwise, add a REG_LABEL note for LABEL unless there already
4005 is one. */
4006 else if (! find_reg_note (insn, REG_LABEL, label))
4007 {
4008 /* This code used to ignore labels which refered to dispatch
4009 tables to avoid flow.c generating worse code.
4010
4011 However, in the presense of global optimizations like
4012 gcse which call find_basic_blocks without calling
4013 life_analysis, not recording such labels will lead
4014 to compiler aborts because of inconsistencies in the
4015 flow graph. So we go ahead and record the label.
4016
4017 It may also be the case that the optimization argument
4018 is no longer valid because of the more accurate cfg
4019 we build in find_basic_blocks -- it no longer pessimizes
4020 code when it finds a REG_LABEL note. */
4021 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
4022 REG_NOTES (insn));
4023 }
4024 }
4025 return;
4026 }
4027
4028 /* Do walk the labels in a vector, but not the first operand of an
4029 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
4030 case ADDR_VEC:
4031 case ADDR_DIFF_VEC:
4032 if (! INSN_DELETED_P (insn))
4033 {
4034 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
4035
4036 for (i = 0; i < XVECLEN (x, eltnum); i++)
4037 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
4038 }
4039 return;
4040
4041 default:
4042 break;
4043 }
4044
4045 fmt = GET_RTX_FORMAT (code);
4046 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4047 {
4048 if (fmt[i] == 'e')
4049 mark_jump_label (XEXP (x, i), insn, cross_jump);
4050 else if (fmt[i] == 'E')
4051 {
4052 register int j;
4053 for (j = 0; j < XVECLEN (x, i); j++)
4054 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
4055 }
4056 }
4057 }
4058
4059 /* If all INSN does is set the pc, delete it,
4060 and delete the insn that set the condition codes for it
4061 if that's what the previous thing was. */
4062
4063 void
4064 delete_jump (insn)
4065 rtx insn;
4066 {
4067 register rtx set = single_set (insn);
4068
4069 if (set && GET_CODE (SET_DEST (set)) == PC)
4070 delete_computation (insn);
4071 }
4072
4073 /* Verify INSN is a BARRIER and delete it. */
4074
4075 void
4076 delete_barrier (insn)
4077 rtx insn;
4078 {
4079 if (GET_CODE (insn) != BARRIER)
4080 abort ();
4081
4082 delete_insn (insn);
4083 }
4084
4085 /* Recursively delete prior insns that compute the value (used only by INSN
4086 which the caller is deleting) stored in the register mentioned by NOTE
4087 which is a REG_DEAD note associated with INSN. */
4088
4089 static void
4090 delete_prior_computation (note, insn)
4091 rtx note;
4092 rtx insn;
4093 {
4094 rtx our_prev;
4095 rtx reg = XEXP (note, 0);
4096
4097 for (our_prev = prev_nonnote_insn (insn);
4098 our_prev && (GET_CODE (our_prev) == INSN
4099 || GET_CODE (our_prev) == CALL_INSN);
4100 our_prev = prev_nonnote_insn (our_prev))
4101 {
4102 rtx pat = PATTERN (our_prev);
4103
4104 /* If we reach a CALL which is not calling a const function
4105 or the callee pops the arguments, then give up. */
4106 if (GET_CODE (our_prev) == CALL_INSN
4107 && (! CONST_CALL_P (our_prev)
4108 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
4109 break;
4110
4111 /* If we reach a SEQUENCE, it is too complex to try to
4112 do anything with it, so give up. */
4113 if (GET_CODE (pat) == SEQUENCE)
4114 break;
4115
4116 if (GET_CODE (pat) == USE
4117 && GET_CODE (XEXP (pat, 0)) == INSN)
4118 /* reorg creates USEs that look like this. We leave them
4119 alone because reorg needs them for its own purposes. */
4120 break;
4121
4122 if (reg_set_p (reg, pat))
4123 {
4124 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
4125 break;
4126
4127 if (GET_CODE (pat) == PARALLEL)
4128 {
4129 /* If we find a SET of something else, we can't
4130 delete the insn. */
4131
4132 int i;
4133
4134 for (i = 0; i < XVECLEN (pat, 0); i++)
4135 {
4136 rtx part = XVECEXP (pat, 0, i);
4137
4138 if (GET_CODE (part) == SET
4139 && SET_DEST (part) != reg)
4140 break;
4141 }
4142
4143 if (i == XVECLEN (pat, 0))
4144 delete_computation (our_prev);
4145 }
4146 else if (GET_CODE (pat) == SET
4147 && GET_CODE (SET_DEST (pat)) == REG)
4148 {
4149 int dest_regno = REGNO (SET_DEST (pat));
4150 int dest_endregno
4151 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
4152 ? HARD_REGNO_NREGS (dest_regno,
4153 GET_MODE (SET_DEST (pat))) : 1);
4154 int regno = REGNO (reg);
4155 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
4156 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
4157
4158 if (dest_regno >= regno
4159 && dest_endregno <= endregno)
4160 delete_computation (our_prev);
4161
4162 /* We may have a multi-word hard register and some, but not
4163 all, of the words of the register are needed in subsequent
4164 insns. Write REG_UNUSED notes for those parts that were not
4165 needed. */
4166 else if (dest_regno <= regno
4167 && dest_endregno >= endregno)
4168 {
4169 int i;
4170
4171 REG_NOTES (our_prev)
4172 = gen_rtx_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (our_prev));
4173
4174 for (i = dest_regno; i < dest_endregno; i++)
4175 if (! find_regno_note (our_prev, REG_UNUSED, i))
4176 break;
4177
4178 if (i == dest_endregno)
4179 delete_computation (our_prev);
4180 }
4181 }
4182
4183 break;
4184 }
4185
4186 /* If PAT references the register that dies here, it is an
4187 additional use. Hence any prior SET isn't dead. However, this
4188 insn becomes the new place for the REG_DEAD note. */
4189 if (reg_overlap_mentioned_p (reg, pat))
4190 {
4191 XEXP (note, 1) = REG_NOTES (our_prev);
4192 REG_NOTES (our_prev) = note;
4193 break;
4194 }
4195 }
4196 }
4197
4198 /* Delete INSN and recursively delete insns that compute values used only
4199 by INSN. This uses the REG_DEAD notes computed during flow analysis.
4200 If we are running before flow.c, we need do nothing since flow.c will
4201 delete dead code. We also can't know if the registers being used are
4202 dead or not at this point.
4203
4204 Otherwise, look at all our REG_DEAD notes. If a previous insn does
4205 nothing other than set a register that dies in this insn, we can delete
4206 that insn as well.
4207
4208 On machines with CC0, if CC0 is used in this insn, we may be able to
4209 delete the insn that set it. */
4210
4211 static void
4212 delete_computation (insn)
4213 rtx insn;
4214 {
4215 rtx note, next;
4216 rtx set;
4217
4218 #ifdef HAVE_cc0
4219 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
4220 {
4221 rtx prev = prev_nonnote_insn (insn);
4222 /* We assume that at this stage
4223 CC's are always set explicitly
4224 and always immediately before the jump that
4225 will use them. So if the previous insn
4226 exists to set the CC's, delete it
4227 (unless it performs auto-increments, etc.). */
4228 if (prev && GET_CODE (prev) == INSN
4229 && sets_cc0_p (PATTERN (prev)))
4230 {
4231 if (sets_cc0_p (PATTERN (prev)) > 0
4232 && ! side_effects_p (PATTERN (prev)))
4233 delete_computation (prev);
4234 else
4235 /* Otherwise, show that cc0 won't be used. */
4236 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
4237 cc0_rtx, REG_NOTES (prev));
4238 }
4239 }
4240 #endif
4241
4242 #ifdef INSN_SCHEDULING
4243 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
4244 reload has completed. The schedulers need to be fixed. Until
4245 they are, we must not rely on the death notes here. */
4246 if (reload_completed && flag_schedule_insns_after_reload)
4247 {
4248 delete_insn (insn);
4249 return;
4250 }
4251 #endif
4252
4253 /* The REG_DEAD note may have been omitted for a register
4254 which is both set and used by the insn. */
4255 set = single_set (insn);
4256 if (set && GET_CODE (SET_DEST (set)) == REG)
4257 {
4258 int dest_regno = REGNO (SET_DEST (set));
4259 int dest_endregno
4260 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
4261 ? HARD_REGNO_NREGS (dest_regno,
4262 GET_MODE (SET_DEST (set))) : 1);
4263 int i;
4264
4265 for (i = dest_regno; i < dest_endregno; i++)
4266 {
4267 if (! refers_to_regno_p (i, i + 1, SET_SRC (set), NULL_PTR)
4268 || find_regno_note (insn, REG_DEAD, i))
4269 continue;
4270
4271 note = gen_rtx_EXPR_LIST (REG_DEAD, (i < FIRST_PSEUDO_REGISTER
4272 ? gen_rtx_REG (reg_raw_mode[i], i)
4273 : SET_DEST (set)), NULL_RTX);
4274 delete_prior_computation (note, insn);
4275 }
4276 }
4277
4278 for (note = REG_NOTES (insn); note; note = next)
4279 {
4280 next = XEXP (note, 1);
4281
4282 if (REG_NOTE_KIND (note) != REG_DEAD
4283 /* Verify that the REG_NOTE is legitimate. */
4284 || GET_CODE (XEXP (note, 0)) != REG)
4285 continue;
4286
4287 delete_prior_computation (note, insn);
4288 }
4289
4290 delete_insn (insn);
4291 }
4292 \f
4293 /* Delete insn INSN from the chain of insns and update label ref counts.
4294 May delete some following insns as a consequence; may even delete
4295 a label elsewhere and insns that follow it.
4296
4297 Returns the first insn after INSN that was not deleted. */
4298
4299 rtx
4300 delete_insn (insn)
4301 register rtx insn;
4302 {
4303 register rtx next = NEXT_INSN (insn);
4304 register rtx prev = PREV_INSN (insn);
4305 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
4306 register int dont_really_delete = 0;
4307
4308 while (next && INSN_DELETED_P (next))
4309 next = NEXT_INSN (next);
4310
4311 /* This insn is already deleted => return first following nondeleted. */
4312 if (INSN_DELETED_P (insn))
4313 return next;
4314
4315 if (was_code_label)
4316 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
4317
4318 /* Don't delete user-declared labels. Convert them to special NOTEs
4319 instead. */
4320 if (was_code_label && LABEL_NAME (insn) != 0
4321 && optimize && ! dont_really_delete)
4322 {
4323 PUT_CODE (insn, NOTE);
4324 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
4325 NOTE_SOURCE_FILE (insn) = 0;
4326 dont_really_delete = 1;
4327 }
4328 else
4329 /* Mark this insn as deleted. */
4330 INSN_DELETED_P (insn) = 1;
4331
4332 /* If this is an unconditional jump, delete it from the jump chain. */
4333 if (simplejump_p (insn))
4334 delete_from_jump_chain (insn);
4335
4336 /* If instruction is followed by a barrier,
4337 delete the barrier too. */
4338
4339 if (next != 0 && GET_CODE (next) == BARRIER)
4340 {
4341 INSN_DELETED_P (next) = 1;
4342 next = NEXT_INSN (next);
4343 }
4344
4345 /* Patch out INSN (and the barrier if any) */
4346
4347 if (optimize && ! dont_really_delete)
4348 {
4349 if (prev)
4350 {
4351 NEXT_INSN (prev) = next;
4352 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
4353 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
4354 XVECLEN (PATTERN (prev), 0) - 1)) = next;
4355 }
4356
4357 if (next)
4358 {
4359 PREV_INSN (next) = prev;
4360 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
4361 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
4362 }
4363
4364 if (prev && NEXT_INSN (prev) == 0)
4365 set_last_insn (prev);
4366 }
4367
4368 /* If deleting a jump, decrement the count of the label,
4369 and delete the label if it is now unused. */
4370
4371 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
4372 {
4373 rtx lab = JUMP_LABEL (insn), lab_next;
4374
4375 if (--LABEL_NUSES (lab) == 0)
4376 {
4377 /* This can delete NEXT or PREV,
4378 either directly if NEXT is JUMP_LABEL (INSN),
4379 or indirectly through more levels of jumps. */
4380 delete_insn (lab);
4381
4382 /* I feel a little doubtful about this loop,
4383 but I see no clean and sure alternative way
4384 to find the first insn after INSN that is not now deleted.
4385 I hope this works. */
4386 while (next && INSN_DELETED_P (next))
4387 next = NEXT_INSN (next);
4388 return next;
4389 }
4390 else if ((lab_next = next_nonnote_insn (lab)) != NULL
4391 && GET_CODE (lab_next) == JUMP_INSN
4392 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
4393 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
4394 {
4395 /* If we're deleting the tablejump, delete the dispatch table.
4396 We may not be able to kill the label immediately preceeding
4397 just yet, as it might be referenced in code leading up to
4398 the tablejump. */
4399 delete_insn (lab_next);
4400 }
4401 }
4402
4403 /* Likewise if we're deleting a dispatch table. */
4404
4405 if (GET_CODE (insn) == JUMP_INSN
4406 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
4407 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
4408 {
4409 rtx pat = PATTERN (insn);
4410 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
4411 int len = XVECLEN (pat, diff_vec_p);
4412
4413 for (i = 0; i < len; i++)
4414 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
4415 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
4416 while (next && INSN_DELETED_P (next))
4417 next = NEXT_INSN (next);
4418 return next;
4419 }
4420
4421 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
4422 prev = PREV_INSN (prev);
4423
4424 /* If INSN was a label and a dispatch table follows it,
4425 delete the dispatch table. The tablejump must have gone already.
4426 It isn't useful to fall through into a table. */
4427
4428 if (was_code_label
4429 && NEXT_INSN (insn) != 0
4430 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
4431 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
4432 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
4433 next = delete_insn (NEXT_INSN (insn));
4434
4435 /* If INSN was a label, delete insns following it if now unreachable. */
4436
4437 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
4438 {
4439 register RTX_CODE code;
4440 while (next != 0
4441 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
4442 || code == NOTE || code == BARRIER
4443 || (code == CODE_LABEL && INSN_DELETED_P (next))))
4444 {
4445 if (code == NOTE
4446 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
4447 next = NEXT_INSN (next);
4448 /* Keep going past other deleted labels to delete what follows. */
4449 else if (code == CODE_LABEL && INSN_DELETED_P (next))
4450 next = NEXT_INSN (next);
4451 else
4452 /* Note: if this deletes a jump, it can cause more
4453 deletion of unreachable code, after a different label.
4454 As long as the value from this recursive call is correct,
4455 this invocation functions correctly. */
4456 next = delete_insn (next);
4457 }
4458 }
4459
4460 return next;
4461 }
4462
4463 /* Advance from INSN till reaching something not deleted
4464 then return that. May return INSN itself. */
4465
4466 rtx
4467 next_nondeleted_insn (insn)
4468 rtx insn;
4469 {
4470 while (INSN_DELETED_P (insn))
4471 insn = NEXT_INSN (insn);
4472 return insn;
4473 }
4474 \f
4475 /* Delete a range of insns from FROM to TO, inclusive.
4476 This is for the sake of peephole optimization, so assume
4477 that whatever these insns do will still be done by a new
4478 peephole insn that will replace them. */
4479
4480 void
4481 delete_for_peephole (from, to)
4482 register rtx from, to;
4483 {
4484 register rtx insn = from;
4485
4486 while (1)
4487 {
4488 register rtx next = NEXT_INSN (insn);
4489 register rtx prev = PREV_INSN (insn);
4490
4491 if (GET_CODE (insn) != NOTE)
4492 {
4493 INSN_DELETED_P (insn) = 1;
4494
4495 /* Patch this insn out of the chain. */
4496 /* We don't do this all at once, because we
4497 must preserve all NOTEs. */
4498 if (prev)
4499 NEXT_INSN (prev) = next;
4500
4501 if (next)
4502 PREV_INSN (next) = prev;
4503 }
4504
4505 if (insn == to)
4506 break;
4507 insn = next;
4508 }
4509
4510 /* Note that if TO is an unconditional jump
4511 we *do not* delete the BARRIER that follows,
4512 since the peephole that replaces this sequence
4513 is also an unconditional jump in that case. */
4514 }
4515 \f
4516 /* We have determined that INSN is never reached, and are about to
4517 delete it. Print a warning if the user asked for one.
4518
4519 To try to make this warning more useful, this should only be called
4520 once per basic block not reached, and it only warns when the basic
4521 block contains more than one line from the current function, and
4522 contains at least one operation. CSE and inlining can duplicate insns,
4523 so it's possible to get spurious warnings from this. */
4524
4525 void
4526 never_reached_warning (avoided_insn)
4527 rtx avoided_insn;
4528 {
4529 rtx insn;
4530 rtx a_line_note = NULL;
4531 int two_avoided_lines = 0;
4532 int contains_insn = 0;
4533
4534 if (! warn_notreached)
4535 return;
4536
4537 /* Scan forwards, looking at LINE_NUMBER notes, until
4538 we hit a LABEL or we run out of insns. */
4539
4540 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
4541 {
4542 if (GET_CODE (insn) == CODE_LABEL)
4543 break;
4544 else if (GET_CODE (insn) == NOTE /* A line number note? */
4545 && NOTE_LINE_NUMBER (insn) >= 0)
4546 {
4547 if (a_line_note == NULL)
4548 a_line_note = insn;
4549 else
4550 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
4551 != NOTE_LINE_NUMBER (insn));
4552 }
4553 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
4554 contains_insn = 1;
4555 }
4556 if (two_avoided_lines && contains_insn)
4557 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
4558 NOTE_LINE_NUMBER (a_line_note),
4559 "will never be executed");
4560 }
4561 \f
4562 /* Invert the condition of the jump JUMP, and make it jump
4563 to label NLABEL instead of where it jumps now. */
4564
4565 int
4566 invert_jump (jump, nlabel)
4567 rtx jump, nlabel;
4568 {
4569 /* We have to either invert the condition and change the label or
4570 do neither. Either operation could fail. We first try to invert
4571 the jump. If that succeeds, we try changing the label. If that fails,
4572 we invert the jump back to what it was. */
4573
4574 if (! invert_exp (PATTERN (jump), jump))
4575 return 0;
4576
4577 if (redirect_jump (jump, nlabel))
4578 {
4579 if (flag_branch_probabilities)
4580 {
4581 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
4582
4583 /* An inverted jump means that a probability taken becomes a
4584 probability not taken. Subtract the branch probability from the
4585 probability base to convert it back to a taken probability.
4586 (We don't flip the probability on a branch that's never taken. */
4587 if (note && XINT (XEXP (note, 0), 0) >= 0)
4588 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
4589 }
4590
4591 return 1;
4592 }
4593
4594 if (! invert_exp (PATTERN (jump), jump))
4595 /* This should just be putting it back the way it was. */
4596 abort ();
4597
4598 return 0;
4599 }
4600
4601 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4602
4603 Return 1 if we can do so, 0 if we cannot find a way to do so that
4604 matches a pattern. */
4605
4606 int
4607 invert_exp (x, insn)
4608 rtx x;
4609 rtx insn;
4610 {
4611 register RTX_CODE code;
4612 register int i;
4613 register const char *fmt;
4614
4615 code = GET_CODE (x);
4616
4617 if (code == IF_THEN_ELSE)
4618 {
4619 register rtx comp = XEXP (x, 0);
4620 register rtx tem;
4621
4622 /* We can do this in two ways: The preferable way, which can only
4623 be done if this is not an integer comparison, is to reverse
4624 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4625 of the IF_THEN_ELSE. If we can't do either, fail. */
4626
4627 if (can_reverse_comparison_p (comp, insn)
4628 && validate_change (insn, &XEXP (x, 0),
4629 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
4630 GET_MODE (comp), XEXP (comp, 0),
4631 XEXP (comp, 1)), 0))
4632 return 1;
4633
4634 tem = XEXP (x, 1);
4635 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
4636 validate_change (insn, &XEXP (x, 2), tem, 1);
4637 return apply_change_group ();
4638 }
4639
4640 fmt = GET_RTX_FORMAT (code);
4641 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4642 {
4643 if (fmt[i] == 'e')
4644 if (! invert_exp (XEXP (x, i), insn))
4645 return 0;
4646 if (fmt[i] == 'E')
4647 {
4648 register int j;
4649 for (j = 0; j < XVECLEN (x, i); j++)
4650 if (!invert_exp (XVECEXP (x, i, j), insn))
4651 return 0;
4652 }
4653 }
4654
4655 return 1;
4656 }
4657 \f
4658 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4659 If the old jump target label is unused as a result,
4660 it and the code following it may be deleted.
4661
4662 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4663 RETURN insn.
4664
4665 The return value will be 1 if the change was made, 0 if it wasn't (this
4666 can only occur for NLABEL == 0). */
4667
4668 int
4669 redirect_jump (jump, nlabel)
4670 rtx jump, nlabel;
4671 {
4672 register rtx olabel = JUMP_LABEL (jump);
4673
4674 if (nlabel == olabel)
4675 return 1;
4676
4677 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
4678 return 0;
4679
4680 /* If this is an unconditional branch, delete it from the jump_chain of
4681 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4682 have UID's in range and JUMP_CHAIN is valid). */
4683 if (jump_chain && (simplejump_p (jump)
4684 || GET_CODE (PATTERN (jump)) == RETURN))
4685 {
4686 int label_index = nlabel ? INSN_UID (nlabel) : 0;
4687
4688 delete_from_jump_chain (jump);
4689 if (label_index < max_jump_chain
4690 && INSN_UID (jump) < max_jump_chain)
4691 {
4692 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
4693 jump_chain[label_index] = jump;
4694 }
4695 }
4696
4697 JUMP_LABEL (jump) = nlabel;
4698 if (nlabel)
4699 ++LABEL_NUSES (nlabel);
4700
4701 if (olabel && --LABEL_NUSES (olabel) == 0)
4702 delete_insn (olabel);
4703
4704 return 1;
4705 }
4706
4707 /* Delete the instruction JUMP from any jump chain it might be on. */
4708
4709 static void
4710 delete_from_jump_chain (jump)
4711 rtx jump;
4712 {
4713 int index;
4714 rtx olabel = JUMP_LABEL (jump);
4715
4716 /* Handle unconditional jumps. */
4717 if (jump_chain && olabel != 0
4718 && INSN_UID (olabel) < max_jump_chain
4719 && simplejump_p (jump))
4720 index = INSN_UID (olabel);
4721 /* Handle return insns. */
4722 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
4723 index = 0;
4724 else return;
4725
4726 if (jump_chain[index] == jump)
4727 jump_chain[index] = jump_chain[INSN_UID (jump)];
4728 else
4729 {
4730 rtx insn;
4731
4732 for (insn = jump_chain[index];
4733 insn != 0;
4734 insn = jump_chain[INSN_UID (insn)])
4735 if (jump_chain[INSN_UID (insn)] == jump)
4736 {
4737 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
4738 break;
4739 }
4740 }
4741 }
4742
4743 /* If NLABEL is nonzero, throughout the rtx at LOC,
4744 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4745 zero, alter (RETURN) to (LABEL_REF NLABEL).
4746
4747 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4748 validity with validate_change. Convert (set (pc) (label_ref olabel))
4749 to (return).
4750
4751 Return 0 if we found a change we would like to make but it is invalid.
4752 Otherwise, return 1. */
4753
4754 int
4755 redirect_exp (loc, olabel, nlabel, insn)
4756 rtx *loc;
4757 rtx olabel, nlabel;
4758 rtx insn;
4759 {
4760 register rtx x = *loc;
4761 register RTX_CODE code = GET_CODE (x);
4762 register int i;
4763 register const char *fmt;
4764
4765 if (code == LABEL_REF)
4766 {
4767 if (XEXP (x, 0) == olabel)
4768 {
4769 if (nlabel)
4770 XEXP (x, 0) = nlabel;
4771 else
4772 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4773 return 1;
4774 }
4775 }
4776 else if (code == RETURN && olabel == 0)
4777 {
4778 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4779 if (loc == &PATTERN (insn))
4780 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4781 return validate_change (insn, loc, x, 0);
4782 }
4783
4784 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4785 && GET_CODE (SET_SRC (x)) == LABEL_REF
4786 && XEXP (SET_SRC (x), 0) == olabel)
4787 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4788
4789 fmt = GET_RTX_FORMAT (code);
4790 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4791 {
4792 if (fmt[i] == 'e')
4793 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4794 return 0;
4795 if (fmt[i] == 'E')
4796 {
4797 register int j;
4798 for (j = 0; j < XVECLEN (x, i); j++)
4799 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4800 return 0;
4801 }
4802 }
4803
4804 return 1;
4805 }
4806 \f
4807 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4808
4809 If the old jump target label (before the dispatch table) becomes unused,
4810 it and the dispatch table may be deleted. In that case, find the insn
4811 before the jump references that label and delete it and logical successors
4812 too. */
4813
4814 static void
4815 redirect_tablejump (jump, nlabel)
4816 rtx jump, nlabel;
4817 {
4818 register rtx olabel = JUMP_LABEL (jump);
4819
4820 /* Add this jump to the jump_chain of NLABEL. */
4821 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4822 && INSN_UID (jump) < max_jump_chain)
4823 {
4824 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4825 jump_chain[INSN_UID (nlabel)] = jump;
4826 }
4827
4828 PATTERN (jump) = gen_jump (nlabel);
4829 JUMP_LABEL (jump) = nlabel;
4830 ++LABEL_NUSES (nlabel);
4831 INSN_CODE (jump) = -1;
4832
4833 if (--LABEL_NUSES (olabel) == 0)
4834 {
4835 delete_labelref_insn (jump, olabel, 0);
4836 delete_insn (olabel);
4837 }
4838 }
4839
4840 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4841 If we found one, delete it and then delete this insn if DELETE_THIS is
4842 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4843
4844 static int
4845 delete_labelref_insn (insn, label, delete_this)
4846 rtx insn, label;
4847 int delete_this;
4848 {
4849 int deleted = 0;
4850 rtx link;
4851
4852 if (GET_CODE (insn) != NOTE
4853 && reg_mentioned_p (label, PATTERN (insn)))
4854 {
4855 if (delete_this)
4856 {
4857 delete_insn (insn);
4858 deleted = 1;
4859 }
4860 else
4861 return 1;
4862 }
4863
4864 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4865 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4866 {
4867 if (delete_this)
4868 {
4869 delete_insn (insn);
4870 deleted = 1;
4871 }
4872 else
4873 return 1;
4874 }
4875
4876 return deleted;
4877 }
4878 \f
4879 /* Like rtx_equal_p except that it considers two REGs as equal
4880 if they renumber to the same value and considers two commutative
4881 operations to be the same if the order of the operands has been
4882 reversed.
4883
4884 ??? Addition is not commutative on the PA due to the weird implicit
4885 space register selection rules for memory addresses. Therefore, we
4886 don't consider a + b == b + a.
4887
4888 We could/should make this test a little tighter. Possibly only
4889 disabling it on the PA via some backend macro or only disabling this
4890 case when the PLUS is inside a MEM. */
4891
4892 int
4893 rtx_renumbered_equal_p (x, y)
4894 rtx x, y;
4895 {
4896 register int i;
4897 register RTX_CODE code = GET_CODE (x);
4898 register const char *fmt;
4899
4900 if (x == y)
4901 return 1;
4902
4903 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4904 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4905 && GET_CODE (SUBREG_REG (y)) == REG)))
4906 {
4907 int reg_x = -1, reg_y = -1;
4908 int word_x = 0, word_y = 0;
4909
4910 if (GET_MODE (x) != GET_MODE (y))
4911 return 0;
4912
4913 /* If we haven't done any renumbering, don't
4914 make any assumptions. */
4915 if (reg_renumber == 0)
4916 return rtx_equal_p (x, y);
4917
4918 if (code == SUBREG)
4919 {
4920 reg_x = REGNO (SUBREG_REG (x));
4921 word_x = SUBREG_WORD (x);
4922
4923 if (reg_renumber[reg_x] >= 0)
4924 {
4925 reg_x = reg_renumber[reg_x] + word_x;
4926 word_x = 0;
4927 }
4928 }
4929
4930 else
4931 {
4932 reg_x = REGNO (x);
4933 if (reg_renumber[reg_x] >= 0)
4934 reg_x = reg_renumber[reg_x];
4935 }
4936
4937 if (GET_CODE (y) == SUBREG)
4938 {
4939 reg_y = REGNO (SUBREG_REG (y));
4940 word_y = SUBREG_WORD (y);
4941
4942 if (reg_renumber[reg_y] >= 0)
4943 {
4944 reg_y = reg_renumber[reg_y];
4945 word_y = 0;
4946 }
4947 }
4948
4949 else
4950 {
4951 reg_y = REGNO (y);
4952 if (reg_renumber[reg_y] >= 0)
4953 reg_y = reg_renumber[reg_y];
4954 }
4955
4956 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4957 }
4958
4959 /* Now we have disposed of all the cases
4960 in which different rtx codes can match. */
4961 if (code != GET_CODE (y))
4962 return 0;
4963
4964 switch (code)
4965 {
4966 case PC:
4967 case CC0:
4968 case ADDR_VEC:
4969 case ADDR_DIFF_VEC:
4970 return 0;
4971
4972 case CONST_INT:
4973 return INTVAL (x) == INTVAL (y);
4974
4975 case LABEL_REF:
4976 /* We can't assume nonlocal labels have their following insns yet. */
4977 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4978 return XEXP (x, 0) == XEXP (y, 0);
4979
4980 /* Two label-refs are equivalent if they point at labels
4981 in the same position in the instruction stream. */
4982 return (next_real_insn (XEXP (x, 0))
4983 == next_real_insn (XEXP (y, 0)));
4984
4985 case SYMBOL_REF:
4986 return XSTR (x, 0) == XSTR (y, 0);
4987
4988 case CODE_LABEL:
4989 /* If we didn't match EQ equality above, they aren't the same. */
4990 return 0;
4991
4992 default:
4993 break;
4994 }
4995
4996 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4997
4998 if (GET_MODE (x) != GET_MODE (y))
4999 return 0;
5000
5001 /* For commutative operations, the RTX match if the operand match in any
5002 order. Also handle the simple binary and unary cases without a loop.
5003
5004 ??? Don't consider PLUS a commutative operator; see comments above. */
5005 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
5006 && code != PLUS)
5007 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
5008 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
5009 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
5010 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
5011 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
5012 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
5013 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
5014 else if (GET_RTX_CLASS (code) == '1')
5015 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
5016
5017 /* Compare the elements. If any pair of corresponding elements
5018 fail to match, return 0 for the whole things. */
5019
5020 fmt = GET_RTX_FORMAT (code);
5021 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5022 {
5023 register int j;
5024 switch (fmt[i])
5025 {
5026 case 'w':
5027 if (XWINT (x, i) != XWINT (y, i))
5028 return 0;
5029 break;
5030
5031 case 'i':
5032 if (XINT (x, i) != XINT (y, i))
5033 return 0;
5034 break;
5035
5036 case 's':
5037 if (strcmp (XSTR (x, i), XSTR (y, i)))
5038 return 0;
5039 break;
5040
5041 case 'e':
5042 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
5043 return 0;
5044 break;
5045
5046 case 'u':
5047 if (XEXP (x, i) != XEXP (y, i))
5048 return 0;
5049 /* fall through. */
5050 case '0':
5051 break;
5052
5053 case 'E':
5054 if (XVECLEN (x, i) != XVECLEN (y, i))
5055 return 0;
5056 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5057 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
5058 return 0;
5059 break;
5060
5061 default:
5062 abort ();
5063 }
5064 }
5065 return 1;
5066 }
5067 \f
5068 /* If X is a hard register or equivalent to one or a subregister of one,
5069 return the hard register number. If X is a pseudo register that was not
5070 assigned a hard register, return the pseudo register number. Otherwise,
5071 return -1. Any rtx is valid for X. */
5072
5073 int
5074 true_regnum (x)
5075 rtx x;
5076 {
5077 if (GET_CODE (x) == REG)
5078 {
5079 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
5080 return reg_renumber[REGNO (x)];
5081 return REGNO (x);
5082 }
5083 if (GET_CODE (x) == SUBREG)
5084 {
5085 int base = true_regnum (SUBREG_REG (x));
5086 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
5087 return SUBREG_WORD (x) + base;
5088 }
5089 return -1;
5090 }
5091 \f
5092 /* Optimize code of the form:
5093
5094 for (x = a[i]; x; ...)
5095 ...
5096 for (x = a[i]; x; ...)
5097 ...
5098 foo:
5099
5100 Loop optimize will change the above code into
5101
5102 if (x = a[i])
5103 for (;;)
5104 { ...; if (! (x = ...)) break; }
5105 if (x = a[i])
5106 for (;;)
5107 { ...; if (! (x = ...)) break; }
5108 foo:
5109
5110 In general, if the first test fails, the program can branch
5111 directly to `foo' and skip the second try which is doomed to fail.
5112 We run this after loop optimization and before flow analysis. */
5113
5114 /* When comparing the insn patterns, we track the fact that different
5115 pseudo-register numbers may have been used in each computation.
5116 The following array stores an equivalence -- same_regs[I] == J means
5117 that pseudo register I was used in the first set of tests in a context
5118 where J was used in the second set. We also count the number of such
5119 pending equivalences. If nonzero, the expressions really aren't the
5120 same. */
5121
5122 static int *same_regs;
5123
5124 static int num_same_regs;
5125
5126 /* Track any registers modified between the target of the first jump and
5127 the second jump. They never compare equal. */
5128
5129 static char *modified_regs;
5130
5131 /* Record if memory was modified. */
5132
5133 static int modified_mem;
5134
5135 /* Called via note_stores on each insn between the target of the first
5136 branch and the second branch. It marks any changed registers. */
5137
5138 static void
5139 mark_modified_reg (dest, x, data)
5140 rtx dest;
5141 rtx x ATTRIBUTE_UNUSED;
5142 void *data ATTRIBUTE_UNUSED;
5143 {
5144 int regno, i;
5145
5146 if (GET_CODE (dest) == SUBREG)
5147 dest = SUBREG_REG (dest);
5148
5149 if (GET_CODE (dest) == MEM)
5150 modified_mem = 1;
5151
5152 if (GET_CODE (dest) != REG)
5153 return;
5154
5155 regno = REGNO (dest);
5156 if (regno >= FIRST_PSEUDO_REGISTER)
5157 modified_regs[regno] = 1;
5158 else
5159 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
5160 modified_regs[regno + i] = 1;
5161 }
5162
5163 /* F is the first insn in the chain of insns. */
5164
5165 void
5166 thread_jumps (f, max_reg, flag_before_loop)
5167 rtx f;
5168 int max_reg;
5169 int flag_before_loop;
5170 {
5171 /* Basic algorithm is to find a conditional branch,
5172 the label it may branch to, and the branch after
5173 that label. If the two branches test the same condition,
5174 walk back from both branch paths until the insn patterns
5175 differ, or code labels are hit. If we make it back to
5176 the target of the first branch, then we know that the first branch
5177 will either always succeed or always fail depending on the relative
5178 senses of the two branches. So adjust the first branch accordingly
5179 in this case. */
5180
5181 rtx label, b1, b2, t1, t2;
5182 enum rtx_code code1, code2;
5183 rtx b1op0, b1op1, b2op0, b2op1;
5184 int changed = 1;
5185 int i;
5186 int *all_reset;
5187
5188 /* Allocate register tables and quick-reset table. */
5189 modified_regs = (char *) xmalloc (max_reg * sizeof (char));
5190 same_regs = (int *) xmalloc (max_reg * sizeof (int));
5191 all_reset = (int *) xmalloc (max_reg * sizeof (int));
5192 for (i = 0; i < max_reg; i++)
5193 all_reset[i] = -1;
5194
5195 while (changed)
5196 {
5197 changed = 0;
5198
5199 for (b1 = f; b1; b1 = NEXT_INSN (b1))
5200 {
5201 /* Get to a candidate branch insn. */
5202 if (GET_CODE (b1) != JUMP_INSN
5203 || ! condjump_p (b1) || simplejump_p (b1)
5204 || JUMP_LABEL (b1) == 0)
5205 continue;
5206
5207 bzero (modified_regs, max_reg * sizeof (char));
5208 modified_mem = 0;
5209
5210 bcopy ((char *) all_reset, (char *) same_regs,
5211 max_reg * sizeof (int));
5212 num_same_regs = 0;
5213
5214 label = JUMP_LABEL (b1);
5215
5216 /* Look for a branch after the target. Record any registers and
5217 memory modified between the target and the branch. Stop when we
5218 get to a label since we can't know what was changed there. */
5219 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
5220 {
5221 if (GET_CODE (b2) == CODE_LABEL)
5222 break;
5223
5224 else if (GET_CODE (b2) == JUMP_INSN)
5225 {
5226 /* If this is an unconditional jump and is the only use of
5227 its target label, we can follow it. */
5228 if (simplejump_p (b2)
5229 && JUMP_LABEL (b2) != 0
5230 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
5231 {
5232 b2 = JUMP_LABEL (b2);
5233 continue;
5234 }
5235 else
5236 break;
5237 }
5238
5239 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
5240 continue;
5241
5242 if (GET_CODE (b2) == CALL_INSN)
5243 {
5244 modified_mem = 1;
5245 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5246 if (call_used_regs[i] && ! fixed_regs[i]
5247 && i != STACK_POINTER_REGNUM
5248 && i != FRAME_POINTER_REGNUM
5249 && i != HARD_FRAME_POINTER_REGNUM
5250 && i != ARG_POINTER_REGNUM)
5251 modified_regs[i] = 1;
5252 }
5253
5254 note_stores (PATTERN (b2), mark_modified_reg, NULL);
5255 }
5256
5257 /* Check the next candidate branch insn from the label
5258 of the first. */
5259 if (b2 == 0
5260 || GET_CODE (b2) != JUMP_INSN
5261 || b2 == b1
5262 || ! condjump_p (b2)
5263 || simplejump_p (b2))
5264 continue;
5265
5266 /* Get the comparison codes and operands, reversing the
5267 codes if appropriate. If we don't have comparison codes,
5268 we can't do anything. */
5269 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
5270 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
5271 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
5272 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
5273 code1 = reverse_condition (code1);
5274
5275 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
5276 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
5277 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
5278 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
5279 code2 = reverse_condition (code2);
5280
5281 /* If they test the same things and knowing that B1 branches
5282 tells us whether or not B2 branches, check if we
5283 can thread the branch. */
5284 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
5285 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
5286 && (comparison_dominates_p (code1, code2)
5287 || (comparison_dominates_p (code1, reverse_condition (code2))
5288 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
5289 0),
5290 b1))))
5291 {
5292 t1 = prev_nonnote_insn (b1);
5293 t2 = prev_nonnote_insn (b2);
5294
5295 while (t1 != 0 && t2 != 0)
5296 {
5297 if (t2 == label)
5298 {
5299 /* We have reached the target of the first branch.
5300 If there are no pending register equivalents,
5301 we know that this branch will either always
5302 succeed (if the senses of the two branches are
5303 the same) or always fail (if not). */
5304 rtx new_label;
5305
5306 if (num_same_regs != 0)
5307 break;
5308
5309 if (comparison_dominates_p (code1, code2))
5310 new_label = JUMP_LABEL (b2);
5311 else
5312 new_label = get_label_after (b2);
5313
5314 if (JUMP_LABEL (b1) != new_label)
5315 {
5316 rtx prev = PREV_INSN (new_label);
5317
5318 if (flag_before_loop
5319 && GET_CODE (prev) == NOTE
5320 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
5321 {
5322 /* Don't thread to the loop label. If a loop
5323 label is reused, loop optimization will
5324 be disabled for that loop. */
5325 new_label = gen_label_rtx ();
5326 emit_label_after (new_label, PREV_INSN (prev));
5327 }
5328 changed |= redirect_jump (b1, new_label);
5329 }
5330 break;
5331 }
5332
5333 /* If either of these is not a normal insn (it might be
5334 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
5335 have already been skipped above.) Similarly, fail
5336 if the insns are different. */
5337 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
5338 || recog_memoized (t1) != recog_memoized (t2)
5339 || ! rtx_equal_for_thread_p (PATTERN (t1),
5340 PATTERN (t2), t2))
5341 break;
5342
5343 t1 = prev_nonnote_insn (t1);
5344 t2 = prev_nonnote_insn (t2);
5345 }
5346 }
5347 }
5348 }
5349
5350 /* Clean up. */
5351 free (modified_regs);
5352 free (same_regs);
5353 free (all_reset);
5354 }
5355 \f
5356 /* This is like RTX_EQUAL_P except that it knows about our handling of
5357 possibly equivalent registers and knows to consider volatile and
5358 modified objects as not equal.
5359
5360 YINSN is the insn containing Y. */
5361
5362 int
5363 rtx_equal_for_thread_p (x, y, yinsn)
5364 rtx x, y;
5365 rtx yinsn;
5366 {
5367 register int i;
5368 register int j;
5369 register enum rtx_code code;
5370 register const char *fmt;
5371
5372 code = GET_CODE (x);
5373 /* Rtx's of different codes cannot be equal. */
5374 if (code != GET_CODE (y))
5375 return 0;
5376
5377 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
5378 (REG:SI x) and (REG:HI x) are NOT equivalent. */
5379
5380 if (GET_MODE (x) != GET_MODE (y))
5381 return 0;
5382
5383 /* For floating-point, consider everything unequal. This is a bit
5384 pessimistic, but this pass would only rarely do anything for FP
5385 anyway. */
5386 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
5387 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
5388 return 0;
5389
5390 /* For commutative operations, the RTX match if the operand match in any
5391 order. Also handle the simple binary and unary cases without a loop. */
5392 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
5393 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
5394 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
5395 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
5396 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
5397 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
5398 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
5399 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
5400 else if (GET_RTX_CLASS (code) == '1')
5401 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
5402
5403 /* Handle special-cases first. */
5404 switch (code)
5405 {
5406 case REG:
5407 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
5408 return 1;
5409
5410 /* If neither is user variable or hard register, check for possible
5411 equivalence. */
5412 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
5413 || REGNO (x) < FIRST_PSEUDO_REGISTER
5414 || REGNO (y) < FIRST_PSEUDO_REGISTER)
5415 return 0;
5416
5417 if (same_regs[REGNO (x)] == -1)
5418 {
5419 same_regs[REGNO (x)] = REGNO (y);
5420 num_same_regs++;
5421
5422 /* If this is the first time we are seeing a register on the `Y'
5423 side, see if it is the last use. If not, we can't thread the
5424 jump, so mark it as not equivalent. */
5425 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
5426 return 0;
5427
5428 return 1;
5429 }
5430 else
5431 return (same_regs[REGNO (x)] == REGNO (y));
5432
5433 break;
5434
5435 case MEM:
5436 /* If memory modified or either volatile, not equivalent.
5437 Else, check address. */
5438 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5439 return 0;
5440
5441 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
5442
5443 case ASM_INPUT:
5444 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5445 return 0;
5446
5447 break;
5448
5449 case SET:
5450 /* Cancel a pending `same_regs' if setting equivalenced registers.
5451 Then process source. */
5452 if (GET_CODE (SET_DEST (x)) == REG
5453 && GET_CODE (SET_DEST (y)) == REG)
5454 {
5455 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
5456 {
5457 same_regs[REGNO (SET_DEST (x))] = -1;
5458 num_same_regs--;
5459 }
5460 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
5461 return 0;
5462 }
5463 else
5464 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
5465 return 0;
5466
5467 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
5468
5469 case LABEL_REF:
5470 return XEXP (x, 0) == XEXP (y, 0);
5471
5472 case SYMBOL_REF:
5473 return XSTR (x, 0) == XSTR (y, 0);
5474
5475 default:
5476 break;
5477 }
5478
5479 if (x == y)
5480 return 1;
5481
5482 fmt = GET_RTX_FORMAT (code);
5483 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5484 {
5485 switch (fmt[i])
5486 {
5487 case 'w':
5488 if (XWINT (x, i) != XWINT (y, i))
5489 return 0;
5490 break;
5491
5492 case 'n':
5493 case 'i':
5494 if (XINT (x, i) != XINT (y, i))
5495 return 0;
5496 break;
5497
5498 case 'V':
5499 case 'E':
5500 /* Two vectors must have the same length. */
5501 if (XVECLEN (x, i) != XVECLEN (y, i))
5502 return 0;
5503
5504 /* And the corresponding elements must match. */
5505 for (j = 0; j < XVECLEN (x, i); j++)
5506 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
5507 XVECEXP (y, i, j), yinsn) == 0)
5508 return 0;
5509 break;
5510
5511 case 'e':
5512 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
5513 return 0;
5514 break;
5515
5516 case 'S':
5517 case 's':
5518 if (strcmp (XSTR (x, i), XSTR (y, i)))
5519 return 0;
5520 break;
5521
5522 case 'u':
5523 /* These are just backpointers, so they don't matter. */
5524 break;
5525
5526 case '0':
5527 case 't':
5528 break;
5529
5530 /* It is believed that rtx's at this level will never
5531 contain anything but integers and other rtx's,
5532 except for within LABEL_REFs and SYMBOL_REFs. */
5533 default:
5534 abort ();
5535 }
5536 }
5537 return 1;
5538 }
5539 \f
5540
5541 #if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
5542 /* Return the insn that NEW can be safely inserted in front of starting at
5543 the jump insn INSN. Return 0 if it is not safe to do this jump
5544 optimization. Note that NEW must contain a single set. */
5545
5546 static rtx
5547 find_insert_position (insn, new)
5548 rtx insn;
5549 rtx new;
5550 {
5551 int i;
5552 rtx prev;
5553
5554 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
5555 if (GET_CODE (PATTERN (new)) != PARALLEL)
5556 return insn;
5557
5558 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5559 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5560 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5561 insn))
5562 break;
5563
5564 if (i < 0)
5565 return insn;
5566
5567 /* There is a good chance that the previous insn PREV sets the thing
5568 being clobbered (often the CC in a hard reg). If PREV does not
5569 use what NEW sets, we can insert NEW before PREV. */
5570
5571 prev = prev_active_insn (insn);
5572 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5573 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5574 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5575 insn)
5576 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5577 prev))
5578 return 0;
5579
5580 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
5581 }
5582 #endif /* !HAVE_cc0 */