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