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