1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-97, 1998 Free Software Foundation, Inc.
4 This file is part of GNU CC.
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)
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.
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. */
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).
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.
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
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'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
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.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
58 #include "hard-reg-set.h"
60 #include "insn-config.h"
61 #include "insn-flags.h"
68 /* ??? Eventually must record somehow the labels used by jumps
69 from nested functions. */
70 /* Pre-record the next or previous real insn for each label?
71 No, this pass is very fast anyway. */
72 /* Condense consecutive labels?
73 This would make life analysis faster, maybe. */
74 /* Optimize jump y; x: ... y: jumpif... x?
75 Don't know if it is worth bothering with. */
76 /* Optimize two cases of conditional jump to conditional jump?
77 This can never delete any instruction or make anything dead,
78 or even change what is live at any point.
79 So perhaps let combiner do it. */
81 /* Vector indexed by uid.
82 For each CODE_LABEL, index by its uid to get first unconditional jump
83 that jumps to the label.
84 For each JUMP_INSN, index by its uid to get the next unconditional jump
85 that jumps to the same label.
86 Element 0 is the start of a chain of all return insns.
87 (It is safe to use element 0 because insn uid 0 is not used. */
89 static rtx *jump_chain;
91 /* List of labels referred to from initializers.
92 These can never be deleted. */
95 /* Maximum index in jump_chain. */
97 static int max_jump_chain;
99 /* Set nonzero by jump_optimize if control can fall through
100 to the end of the function. */
103 /* Indicates whether death notes are significant in cross jump analysis.
104 Normally they are not significant, because of A and B jump to C,
105 and R dies in A, it must die in B. But this might not be true after
106 stack register conversion, and we must compare death notes in that
109 static int cross_jump_death_matters = 0;
111 static int init_label_info PROTO((rtx));
112 static void delete_barrier_successors PROTO((rtx));
113 static void mark_all_labels PROTO((rtx, int));
114 static rtx delete_unreferenced_labels PROTO((rtx));
115 static void delete_noop_moves PROTO((rtx));
116 static int calculate_can_reach_end PROTO((rtx, int, int));
117 static int duplicate_loop_exit_test PROTO((rtx));
118 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
119 static void do_cross_jump PROTO((rtx, rtx, rtx));
120 static int jump_back_p PROTO((rtx, rtx));
121 static int tension_vector_labels PROTO((rtx, int));
122 static void mark_jump_label PROTO((rtx, rtx, int));
123 static void delete_computation PROTO((rtx));
124 static void delete_from_jump_chain PROTO((rtx));
125 static int delete_labelref_insn PROTO((rtx, rtx, int));
126 static void mark_modified_reg PROTO((rtx, rtx));
127 static void redirect_tablejump PROTO((rtx, rtx));
129 static rtx find_insert_position PROTO((rtx, rtx));
132 /* Delete no-op jumps and optimize jumps to jumps
133 and jumps around jumps.
134 Delete unused labels and unreachable code.
136 If CROSS_JUMP is 1, detect matching code
137 before a jump and its destination and unify them.
138 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
140 If NOOP_MOVES is nonzero, delete no-op move insns.
142 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
143 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
145 If `optimize' is zero, don't change any code,
146 just determine whether control drops off the end of the function.
147 This case occurs when we have -W and not -O.
148 It works because `delete_insn' checks the value of `optimize'
149 and refrains from actually deleting when that is 0. */
152 jump_optimize (f, cross_jump, noop_moves, after_regscan)
158 register rtx insn, next;
165 cross_jump_death_matters = (cross_jump == 2);
166 max_uid = init_label_info (f) + 1;
168 /* If we are performing cross jump optimizations, then initialize
169 tables mapping UIDs to EH regions to avoid incorrect movement
170 of insns from one EH region to another. */
171 if (flag_exceptions && cross_jump)
172 init_insn_eh_region (f, max_uid);
174 delete_barrier_successors (f);
176 /* Leave some extra room for labels and duplicate exit test insns
178 max_jump_chain = max_uid * 14 / 10;
179 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
180 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
182 mark_all_labels (f, cross_jump);
184 /* Keep track of labels used from static data;
185 they cannot ever be deleted. */
187 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
188 LABEL_NUSES (XEXP (insn, 0))++;
190 check_exception_handler_labels ();
192 /* Keep track of labels used for marking handlers for exception
193 regions; they cannot usually be deleted. */
195 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
196 LABEL_NUSES (XEXP (insn, 0))++;
198 exception_optimize ();
200 last_insn = delete_unreferenced_labels (f);
204 can_reach_end = calculate_can_reach_end (last_insn, 1, 0);
206 /* Zero the "deleted" flag of all the "deleted" insns. */
207 for (insn = f; insn; insn = NEXT_INSN (insn))
208 INSN_DELETED_P (insn) = 0;
210 /* Show that the jump chain is not valid. */
218 /* If we fall through to the epilogue, see if we can insert a RETURN insn
219 in front of it. If the machine allows it at this point (we might be
220 after reload for a leaf routine), it will improve optimization for it
222 insn = get_last_insn ();
223 while (insn && GET_CODE (insn) == NOTE)
224 insn = PREV_INSN (insn);
226 if (insn && GET_CODE (insn) != BARRIER)
228 emit_jump_insn (gen_return ());
235 delete_noop_moves (f);
237 /* If we haven't yet gotten to reload and we have just run regscan,
238 delete any insn that sets a register that isn't used elsewhere.
239 This helps some of the optimizations below by having less insns
240 being jumped around. */
242 if (! reload_completed && after_regscan)
243 for (insn = f; insn; insn = next)
245 rtx set = single_set (insn);
247 next = NEXT_INSN (insn);
249 if (set && GET_CODE (SET_DEST (set)) == REG
250 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
251 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
252 /* We use regno_last_note_uid so as not to delete the setting
253 of a reg that's used in notes. A subsequent optimization
254 might arrange to use that reg for real. */
255 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
256 && ! side_effects_p (SET_SRC (set))
257 && ! find_reg_note (insn, REG_RETVAL, 0))
261 /* Now iterate optimizing jumps until nothing changes over one pass. */
263 old_max_reg = max_reg_num ();
268 for (insn = f; insn; insn = next)
271 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
273 int this_is_simplejump, this_is_condjump, reversep = 0;
274 int this_is_condjump_in_parallel;
277 /* If NOT the first iteration, if this is the last jump pass
278 (just before final), do the special peephole optimizations.
279 Avoiding the first iteration gives ordinary jump opts
280 a chance to work before peephole opts. */
282 if (reload_completed && !first && !flag_no_peephole)
283 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
287 /* That could have deleted some insns after INSN, so check now
288 what the following insn is. */
290 next = NEXT_INSN (insn);
292 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
293 jump. Try to optimize by duplicating the loop exit test if so.
294 This is only safe immediately after regscan, because it uses
295 the values of regno_first_uid and regno_last_uid. */
296 if (after_regscan && GET_CODE (insn) == NOTE
297 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
298 && (temp1 = next_nonnote_insn (insn)) != 0
299 && simplejump_p (temp1))
301 temp = PREV_INSN (insn);
302 if (duplicate_loop_exit_test (insn))
305 next = NEXT_INSN (temp);
310 if (GET_CODE (insn) != JUMP_INSN)
313 this_is_simplejump = simplejump_p (insn);
314 this_is_condjump = condjump_p (insn);
315 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
317 /* Tension the labels in dispatch tables. */
319 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
320 changed |= tension_vector_labels (PATTERN (insn), 0);
321 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
322 changed |= tension_vector_labels (PATTERN (insn), 1);
324 /* If a dispatch table always goes to the same place,
325 get rid of it and replace the insn that uses it. */
327 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
328 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
331 rtx pat = PATTERN (insn);
332 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
333 int len = XVECLEN (pat, diff_vec_p);
334 rtx dispatch = prev_real_insn (insn);
336 for (i = 0; i < len; i++)
337 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
338 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
342 && GET_CODE (dispatch) == JUMP_INSN
343 && JUMP_LABEL (dispatch) != 0
344 /* Don't mess with a casesi insn. */
345 && !(GET_CODE (PATTERN (dispatch)) == SET
346 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
348 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
350 redirect_tablejump (dispatch,
351 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
356 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
358 /* If a jump references the end of the function, try to turn
359 it into a RETURN insn, possibly a conditional one. */
360 if (JUMP_LABEL (insn)
361 && (next_active_insn (JUMP_LABEL (insn)) == 0
362 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
364 changed |= redirect_jump (insn, NULL_RTX);
366 /* Detect jump to following insn. */
367 if (reallabelprev == insn && condjump_p (insn))
369 next = next_real_insn (JUMP_LABEL (insn));
375 /* If we have an unconditional jump preceded by a USE, try to put
376 the USE before the target and jump there. This simplifies many
377 of the optimizations below since we don't have to worry about
378 dealing with these USE insns. We only do this if the label
379 being branch to already has the identical USE or if code
380 never falls through to that label. */
382 if (this_is_simplejump
383 && (temp = prev_nonnote_insn (insn)) != 0
384 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
385 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
386 && (GET_CODE (temp1) == BARRIER
387 || (GET_CODE (temp1) == INSN
388 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
389 /* Don't do this optimization if we have a loop containing only
390 the USE instruction, and the loop start label has a usage
391 count of 1. This is because we will redo this optimization
392 everytime through the outer loop, and jump opt will never
394 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
395 && temp2 == JUMP_LABEL (insn)
396 && LABEL_NUSES (temp2) == 1))
398 if (GET_CODE (temp1) == BARRIER)
400 emit_insn_after (PATTERN (temp), temp1);
401 temp1 = NEXT_INSN (temp1);
405 redirect_jump (insn, get_label_before (temp1));
406 reallabelprev = prev_real_insn (temp1);
410 /* Simplify if (...) x = a; else x = b; by converting it
411 to x = b; if (...) x = a;
412 if B is sufficiently simple, the test doesn't involve X,
413 and nothing in the test modifies B or X.
415 If we have small register classes, we also can't do this if X
418 If the "x = b;" insn has any REG_NOTES, we don't do this because
419 of the possibility that we are running after CSE and there is a
420 REG_EQUAL note that is only valid if the branch has already been
421 taken. If we move the insn with the REG_EQUAL note, we may
422 fold the comparison to always be false in a later CSE pass.
423 (We could also delete the REG_NOTES when moving the insn, but it
424 seems simpler to not move it.) An exception is that we can move
425 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
426 value is the same as "b".
428 INSN is the branch over the `else' part.
432 TEMP to the jump insn preceding "x = a;"
434 TEMP2 to the insn that sets "x = b;"
435 TEMP3 to the insn that sets "x = a;"
436 TEMP4 to the set of "x = b"; */
438 if (this_is_simplejump
439 && (temp3 = prev_active_insn (insn)) != 0
440 && GET_CODE (temp3) == INSN
441 && (temp4 = single_set (temp3)) != 0
442 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
443 && (! SMALL_REGISTER_CLASSES
444 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
445 && (temp2 = next_active_insn (insn)) != 0
446 && GET_CODE (temp2) == INSN
447 && (temp4 = single_set (temp2)) != 0
448 && rtx_equal_p (SET_DEST (temp4), temp1)
449 && ! side_effects_p (SET_SRC (temp4))
450 && ! may_trap_p (SET_SRC (temp4))
451 && (REG_NOTES (temp2) == 0
452 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
453 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
454 && XEXP (REG_NOTES (temp2), 1) == 0
455 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
457 && (temp = prev_active_insn (temp3)) != 0
458 && condjump_p (temp) && ! simplejump_p (temp)
459 /* TEMP must skip over the "x = a;" insn */
460 && prev_real_insn (JUMP_LABEL (temp)) == insn
461 && no_labels_between_p (insn, JUMP_LABEL (temp))
462 /* There must be no other entries to the "x = b;" insn. */
463 && no_labels_between_p (JUMP_LABEL (temp), temp2)
464 /* INSN must either branch to the insn after TEMP2 or the insn
465 after TEMP2 must branch to the same place as INSN. */
466 && (reallabelprev == temp2
467 || ((temp5 = next_active_insn (temp2)) != 0
468 && simplejump_p (temp5)
469 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
471 /* The test expression, X, may be a complicated test with
472 multiple branches. See if we can find all the uses of
473 the label that TEMP branches to without hitting a CALL_INSN
474 or a jump to somewhere else. */
475 rtx target = JUMP_LABEL (temp);
476 int nuses = LABEL_NUSES (target);
482 /* Set P to the first jump insn that goes around "x = a;". */
483 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
485 if (GET_CODE (p) == JUMP_INSN)
487 if (condjump_p (p) && ! simplejump_p (p)
488 && JUMP_LABEL (p) == target)
497 else if (GET_CODE (p) == CALL_INSN)
502 /* We cannot insert anything between a set of cc and its use
503 so if P uses cc0, we must back up to the previous insn. */
504 q = prev_nonnote_insn (p);
505 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
506 && sets_cc0_p (PATTERN (q)))
513 /* If we found all the uses and there was no data conflict, we
514 can move the assignment unless we can branch into the middle
517 && no_labels_between_p (p, insn)
518 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
519 && ! reg_set_between_p (temp1, p, temp3)
520 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
521 || ! modified_between_p (SET_SRC (temp4), p, temp2))
522 /* Verify that registers used by the jump are not clobbered
523 by the instruction being moved. */
524 && ! regs_set_between_p (PATTERN (temp),
528 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
531 /* Set NEXT to an insn that we know won't go away. */
532 next = next_active_insn (insn);
534 /* Delete the jump around the set. Note that we must do
535 this before we redirect the test jumps so that it won't
536 delete the code immediately following the assignment
537 we moved (which might be a jump). */
541 /* We either have two consecutive labels or a jump to
542 a jump, so adjust all the JUMP_INSNs to branch to where
544 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
545 if (GET_CODE (p) == JUMP_INSN)
546 redirect_jump (p, target);
553 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
554 to x = a; if (...) goto l; x = b;
555 if A is sufficiently simple, the test doesn't involve X,
556 and nothing in the test modifies A or X.
558 If we have small register classes, we also can't do this if X
561 If the "x = a;" insn has any REG_NOTES, we don't do this because
562 of the possibility that we are running after CSE and there is a
563 REG_EQUAL note that is only valid if the branch has already been
564 taken. If we move the insn with the REG_EQUAL note, we may
565 fold the comparison to always be false in a later CSE pass.
566 (We could also delete the REG_NOTES when moving the insn, but it
567 seems simpler to not move it.) An exception is that we can move
568 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
569 value is the same as "a".
575 TEMP to the jump insn preceding "x = a;"
577 TEMP2 to the insn that sets "x = b;"
578 TEMP3 to the insn that sets "x = a;"
579 TEMP4 to the set of "x = a"; */
581 if (this_is_simplejump
582 && (temp2 = next_active_insn (insn)) != 0
583 && GET_CODE (temp2) == INSN
584 && (temp4 = single_set (temp2)) != 0
585 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
586 && (! SMALL_REGISTER_CLASSES
587 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
588 && (temp3 = prev_active_insn (insn)) != 0
589 && GET_CODE (temp3) == INSN
590 && (temp4 = single_set (temp3)) != 0
591 && rtx_equal_p (SET_DEST (temp4), temp1)
592 && ! side_effects_p (SET_SRC (temp4))
593 && ! may_trap_p (SET_SRC (temp4))
594 && (REG_NOTES (temp3) == 0
595 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
596 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
597 && XEXP (REG_NOTES (temp3), 1) == 0
598 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
600 && (temp = prev_active_insn (temp3)) != 0
601 && condjump_p (temp) && ! simplejump_p (temp)
602 /* TEMP must skip over the "x = a;" insn */
603 && prev_real_insn (JUMP_LABEL (temp)) == insn
604 && no_labels_between_p (temp, insn))
606 rtx prev_label = JUMP_LABEL (temp);
607 rtx insert_after = prev_nonnote_insn (temp);
610 /* We cannot insert anything between a set of cc and its use. */
611 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
612 && sets_cc0_p (PATTERN (insert_after)))
613 insert_after = prev_nonnote_insn (insert_after);
615 ++LABEL_NUSES (prev_label);
618 && no_labels_between_p (insert_after, temp)
619 && ! reg_referenced_between_p (temp1, insert_after, temp3)
620 && ! reg_referenced_between_p (temp1, temp3,
622 && ! reg_set_between_p (temp1, insert_after, temp)
623 && ! modified_between_p (SET_SRC (temp4), insert_after, temp)
624 /* Verify that registers used by the jump are not clobbered
625 by the instruction being moved. */
626 && ! regs_set_between_p (PATTERN (temp),
629 && invert_jump (temp, JUMP_LABEL (insn)))
631 emit_insn_after_with_line_notes (PATTERN (temp3),
632 insert_after, temp3);
635 /* Set NEXT to an insn that we know won't go away. */
639 if (prev_label && --LABEL_NUSES (prev_label) == 0)
640 delete_insn (prev_label);
646 /* If we have if (...) x = exp; and branches are expensive,
647 EXP is a single insn, does not have any side effects, cannot
648 trap, and is not too costly, convert this to
649 t = exp; if (...) x = t;
651 Don't do this when we have CC0 because it is unlikely to help
652 and we'd need to worry about where to place the new insn and
653 the potential for conflicts. We also can't do this when we have
654 notes on the insn for the same reason as above.
658 TEMP to the "x = exp;" insn.
659 TEMP1 to the single set in the "x = exp;" insn.
662 if (! reload_completed
663 && this_is_condjump && ! this_is_simplejump
665 && (temp = next_nonnote_insn (insn)) != 0
666 && GET_CODE (temp) == INSN
667 && REG_NOTES (temp) == 0
668 && (reallabelprev == temp
669 || ((temp2 = next_active_insn (temp)) != 0
670 && simplejump_p (temp2)
671 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
672 && (temp1 = single_set (temp)) != 0
673 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
674 && (! SMALL_REGISTER_CLASSES
675 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
676 && GET_CODE (SET_SRC (temp1)) != REG
677 && GET_CODE (SET_SRC (temp1)) != SUBREG
678 && GET_CODE (SET_SRC (temp1)) != CONST_INT
679 && ! side_effects_p (SET_SRC (temp1))
680 && ! may_trap_p (SET_SRC (temp1))
681 && rtx_cost (SET_SRC (temp1), SET) < 10)
683 rtx new = gen_reg_rtx (GET_MODE (temp2));
685 if ((temp3 = find_insert_position (insn, temp))
686 && validate_change (temp, &SET_DEST (temp1), new, 0))
688 next = emit_insn_after (gen_move_insn (temp2, new), insn);
689 emit_insn_after_with_line_notes (PATTERN (temp),
690 PREV_INSN (temp3), temp);
692 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
696 reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
697 old_max_reg = max_reg_num ();
702 /* Similarly, if it takes two insns to compute EXP but they
703 have the same destination. Here TEMP3 will be the second
704 insn and TEMP4 the SET from that insn. */
706 if (! reload_completed
707 && this_is_condjump && ! this_is_simplejump
709 && (temp = next_nonnote_insn (insn)) != 0
710 && GET_CODE (temp) == INSN
711 && REG_NOTES (temp) == 0
712 && (temp3 = next_nonnote_insn (temp)) != 0
713 && GET_CODE (temp3) == INSN
714 && REG_NOTES (temp3) == 0
715 && (reallabelprev == temp3
716 || ((temp2 = next_active_insn (temp3)) != 0
717 && simplejump_p (temp2)
718 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
719 && (temp1 = single_set (temp)) != 0
720 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
721 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
722 && (! SMALL_REGISTER_CLASSES
723 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
724 && ! side_effects_p (SET_SRC (temp1))
725 && ! may_trap_p (SET_SRC (temp1))
726 && rtx_cost (SET_SRC (temp1), SET) < 10
727 && (temp4 = single_set (temp3)) != 0
728 && rtx_equal_p (SET_DEST (temp4), temp2)
729 && ! side_effects_p (SET_SRC (temp4))
730 && ! may_trap_p (SET_SRC (temp4))
731 && rtx_cost (SET_SRC (temp4), SET) < 10)
733 rtx new = gen_reg_rtx (GET_MODE (temp2));
735 if ((temp5 = find_insert_position (insn, temp))
736 && (temp6 = find_insert_position (insn, temp3))
737 && validate_change (temp, &SET_DEST (temp1), new, 0))
739 /* Use the earliest of temp5 and temp6. */
742 next = emit_insn_after (gen_move_insn (temp2, new), insn);
743 emit_insn_after_with_line_notes (PATTERN (temp),
744 PREV_INSN (temp6), temp);
745 emit_insn_after_with_line_notes
746 (replace_rtx (PATTERN (temp3), temp2, new),
747 PREV_INSN (temp6), temp3);
750 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
754 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
755 old_max_reg = max_reg_num ();
760 /* Finally, handle the case where two insns are used to
761 compute EXP but a temporary register is used. Here we must
762 ensure that the temporary register is not used anywhere else. */
764 if (! reload_completed
766 && this_is_condjump && ! this_is_simplejump
768 && (temp = next_nonnote_insn (insn)) != 0
769 && GET_CODE (temp) == INSN
770 && REG_NOTES (temp) == 0
771 && (temp3 = next_nonnote_insn (temp)) != 0
772 && GET_CODE (temp3) == INSN
773 && REG_NOTES (temp3) == 0
774 && (reallabelprev == temp3
775 || ((temp2 = next_active_insn (temp3)) != 0
776 && simplejump_p (temp2)
777 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
778 && (temp1 = single_set (temp)) != 0
779 && (temp5 = SET_DEST (temp1),
780 (GET_CODE (temp5) == REG
781 || (GET_CODE (temp5) == SUBREG
782 && (temp5 = SUBREG_REG (temp5),
783 GET_CODE (temp5) == REG))))
784 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
785 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
786 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
787 && ! side_effects_p (SET_SRC (temp1))
788 && ! may_trap_p (SET_SRC (temp1))
789 && rtx_cost (SET_SRC (temp1), SET) < 10
790 && (temp4 = single_set (temp3)) != 0
791 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
792 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
793 && (! SMALL_REGISTER_CLASSES
794 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
795 && rtx_equal_p (SET_DEST (temp4), temp2)
796 && ! side_effects_p (SET_SRC (temp4))
797 && ! may_trap_p (SET_SRC (temp4))
798 && rtx_cost (SET_SRC (temp4), SET) < 10)
800 rtx new = gen_reg_rtx (GET_MODE (temp2));
802 if ((temp5 = find_insert_position (insn, temp))
803 && (temp6 = find_insert_position (insn, temp3))
804 && validate_change (temp3, &SET_DEST (temp4), new, 0))
806 /* Use the earliest of temp5 and temp6. */
809 next = emit_insn_after (gen_move_insn (temp2, new), insn);
810 emit_insn_after_with_line_notes (PATTERN (temp),
811 PREV_INSN (temp6), temp);
812 emit_insn_after_with_line_notes (PATTERN (temp3),
813 PREV_INSN (temp6), temp3);
816 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
820 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
821 old_max_reg = max_reg_num ();
825 #endif /* HAVE_cc0 */
827 /* Try to use a conditional move (if the target has them), or a
828 store-flag insn. The general case is:
830 1) x = a; if (...) x = b; and
833 If the jump would be faster, the machine should not have defined
834 the movcc or scc insns!. These cases are often made by the
835 previous optimization.
837 The second case is treated as x = x; if (...) x = b;.
839 INSN here is the jump around the store. We set:
841 TEMP to the "x = b;" insn.
844 TEMP3 to A (X in the second case).
845 TEMP4 to the condition being tested.
846 TEMP5 to the earliest insn used to find the condition. */
848 if (/* We can't do this after reload has completed. */
850 && this_is_condjump && ! this_is_simplejump
851 /* Set TEMP to the "x = b;" insn. */
852 && (temp = next_nonnote_insn (insn)) != 0
853 && GET_CODE (temp) == INSN
854 && GET_CODE (PATTERN (temp)) == SET
855 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
856 && (! SMALL_REGISTER_CLASSES
857 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
858 && ! side_effects_p (temp2 = SET_SRC (PATTERN (temp)))
859 && ! may_trap_p (temp2)
860 /* Allow either form, but prefer the former if both apply.
861 There is no point in using the old value of TEMP1 if
862 it is a register, since cse will alias them. It can
863 lose if the old value were a hard register since CSE
864 won't replace hard registers. Avoid using TEMP3 if
865 small register classes and it is a hard register. */
866 && (((temp3 = reg_set_last (temp1, insn)) != 0
867 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
868 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
869 /* Make the latter case look like x = x; if (...) x = b; */
870 || (temp3 = temp1, 1))
871 /* INSN must either branch to the insn after TEMP or the insn
872 after TEMP must branch to the same place as INSN. */
873 && (reallabelprev == temp
874 || ((temp4 = next_active_insn (temp)) != 0
875 && simplejump_p (temp4)
876 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
877 && (temp4 = get_condition (insn, &temp5)) != 0
878 /* We must be comparing objects whose modes imply the size.
879 We could handle BLKmode if (1) emit_store_flag could
880 and (2) we could find the size reliably. */
881 && GET_MODE (XEXP (temp4, 0)) != BLKmode
882 /* Even if branches are cheap, the store_flag optimization
883 can win when the operation to be performed can be
884 expressed directly. */
886 /* If the previous insn sets CC0 and something else, we can't
887 do this since we are going to delete that insn. */
889 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
890 && GET_CODE (temp6) == INSN
891 && (sets_cc0_p (PATTERN (temp6)) == -1
892 || (sets_cc0_p (PATTERN (temp6)) == 1
893 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
897 #ifdef HAVE_conditional_move
898 /* First try a conditional move. */
900 enum rtx_code code = GET_CODE (temp4);
902 rtx cond0, cond1, aval, bval;
905 /* Copy the compared variables into cond0 and cond1, so that
906 any side effects performed in or after the old comparison,
907 will not affect our compare which will come later. */
908 /* ??? Is it possible to just use the comparison in the jump
909 insn? After all, we're going to delete it. We'd have
910 to modify emit_conditional_move to take a comparison rtx
911 instead or write a new function. */
912 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
913 /* We want the target to be able to simplify comparisons with
914 zero (and maybe other constants as well), so don't create
915 pseudos for them. There's no need to either. */
916 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
917 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
918 cond1 = XEXP (temp4, 1);
920 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
926 target = emit_conditional_move (var, code,
927 cond0, cond1, VOIDmode,
928 aval, bval, GET_MODE (var),
929 (code == LTU || code == GEU
930 || code == LEU || code == GTU));
936 /* Save the conditional move sequence but don't emit it
937 yet. On some machines, like the alpha, it is possible
938 that temp5 == insn, so next generate the sequence that
939 saves the compared values and then emit both
940 sequences ensuring seq1 occurs before seq2. */
944 /* Now that we can't fail, generate the copy insns that
945 preserve the compared values. */
947 emit_move_insn (cond0, XEXP (temp4, 0));
948 if (cond1 != XEXP (temp4, 1))
949 emit_move_insn (cond1, XEXP (temp4, 1));
953 emit_insns_before (seq1, temp5);
954 /* Insert conditional move after insn, to be sure that
955 the jump and a possible compare won't be separated */
956 last = emit_insns_after (seq2, insn);
958 /* ??? We can also delete the insn that sets X to A.
959 Flow will do it too though. */
961 next = NEXT_INSN (insn);
966 reg_scan_update (seq1, NEXT_INSN (last), old_max_reg);
967 old_max_reg = max_reg_num ();
978 /* That didn't work, try a store-flag insn.
980 We further divide the cases into:
982 1) x = a; if (...) x = b; and either A or B is zero,
983 2) if (...) x = 0; and jumps are expensive,
984 3) x = a; if (...) x = b; and A and B are constants where all
985 the set bits in A are also set in B and jumps are expensive,
986 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
988 5) if (...) x = b; if jumps are even more expensive. */
990 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
991 && ((GET_CODE (temp3) == CONST_INT)
992 /* Make the latter case look like
993 x = x; if (...) x = 0; */
996 && temp2 == const0_rtx)
997 || BRANCH_COST >= 3)))
998 /* If B is zero, OK; if A is zero, can only do (1) if we
999 can reverse the condition. See if (3) applies possibly
1000 by reversing the condition. Prefer reversing to (4) when
1001 branches are very expensive. */
1002 && (((BRANCH_COST >= 2
1003 || STORE_FLAG_VALUE == -1
1004 || (STORE_FLAG_VALUE == 1
1005 /* Check that the mask is a power of two,
1006 so that it can probably be generated
1008 && GET_CODE (temp3) == CONST_INT
1009 && exact_log2 (INTVAL (temp3)) >= 0))
1010 && (reversep = 0, temp2 == const0_rtx))
1011 || ((BRANCH_COST >= 2
1012 || STORE_FLAG_VALUE == -1
1013 || (STORE_FLAG_VALUE == 1
1014 && GET_CODE (temp2) == CONST_INT
1015 && exact_log2 (INTVAL (temp2)) >= 0))
1016 && temp3 == const0_rtx
1017 && (reversep = can_reverse_comparison_p (temp4, insn)))
1018 || (BRANCH_COST >= 2
1019 && GET_CODE (temp2) == CONST_INT
1020 && GET_CODE (temp3) == CONST_INT
1021 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1022 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1023 && (reversep = can_reverse_comparison_p (temp4,
1025 || BRANCH_COST >= 3)
1028 enum rtx_code code = GET_CODE (temp4);
1029 rtx uval, cval, var = temp1;
1033 /* If necessary, reverse the condition. */
1035 code = reverse_condition (code), uval = temp2, cval = temp3;
1037 uval = temp3, cval = temp2;
1039 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1040 is the constant 1, it is best to just compute the result
1041 directly. If UVAL is constant and STORE_FLAG_VALUE
1042 includes all of its bits, it is best to compute the flag
1043 value unnormalized and `and' it with UVAL. Otherwise,
1044 normalize to -1 and `and' with UVAL. */
1045 normalizep = (cval != const0_rtx ? -1
1046 : (uval == const1_rtx ? 1
1047 : (GET_CODE (uval) == CONST_INT
1048 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1051 /* We will be putting the store-flag insn immediately in
1052 front of the comparison that was originally being done,
1053 so we know all the variables in TEMP4 will be valid.
1054 However, this might be in front of the assignment of
1055 A to VAR. If it is, it would clobber the store-flag
1056 we will be emitting.
1058 Therefore, emit into a temporary which will be copied to
1059 VAR immediately after TEMP. */
1062 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1063 XEXP (temp4, 0), XEXP (temp4, 1),
1065 (code == LTU || code == LEU
1066 || code == GEU || code == GTU),
1076 /* Put the store-flag insns in front of the first insn
1077 used to compute the condition to ensure that we
1078 use the same values of them as the current
1079 comparison. However, the remainder of the insns we
1080 generate will be placed directly in front of the
1081 jump insn, in case any of the pseudos we use
1082 are modified earlier. */
1084 emit_insns_before (seq, temp5);
1088 /* Both CVAL and UVAL are non-zero. */
1089 if (cval != const0_rtx && uval != const0_rtx)
1093 tem1 = expand_and (uval, target, NULL_RTX);
1094 if (GET_CODE (cval) == CONST_INT
1095 && GET_CODE (uval) == CONST_INT
1096 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1100 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1101 target, NULL_RTX, 0);
1102 tem2 = expand_and (cval, tem2,
1103 (GET_CODE (tem2) == REG
1107 /* If we usually make new pseudos, do so here. This
1108 turns out to help machines that have conditional
1110 /* ??? Conditional moves have already been handled.
1111 This may be obsolete. */
1113 if (flag_expensive_optimizations)
1116 target = expand_binop (GET_MODE (var), ior_optab,
1120 else if (normalizep != 1)
1122 /* We know that either CVAL or UVAL is zero. If
1123 UVAL is zero, negate TARGET and `and' with CVAL.
1124 Otherwise, `and' with UVAL. */
1125 if (uval == const0_rtx)
1127 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1128 target, NULL_RTX, 0);
1132 target = expand_and (uval, target,
1133 (GET_CODE (target) == REG
1134 && ! preserve_subexpressions_p ()
1135 ? target : NULL_RTX));
1138 emit_move_insn (var, target);
1142 /* If INSN uses CC0, we must not separate it from the
1143 insn that sets cc0. */
1144 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1145 before = prev_nonnote_insn (before);
1147 emit_insns_before (seq, before);
1150 next = NEXT_INSN (insn);
1155 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1156 old_max_reg = max_reg_num ();
1167 /* If branches are expensive, convert
1168 if (foo) bar++; to bar += (foo != 0);
1169 and similarly for "bar--;"
1171 INSN is the conditional branch around the arithmetic. We set:
1173 TEMP is the arithmetic insn.
1174 TEMP1 is the SET doing the arithmetic.
1175 TEMP2 is the operand being incremented or decremented.
1176 TEMP3 to the condition being tested.
1177 TEMP4 to the earliest insn used to find the condition. */
1179 if ((BRANCH_COST >= 2
1187 && ! reload_completed
1188 && this_is_condjump && ! this_is_simplejump
1189 && (temp = next_nonnote_insn (insn)) != 0
1190 && (temp1 = single_set (temp)) != 0
1191 && (temp2 = SET_DEST (temp1),
1192 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1193 && GET_CODE (SET_SRC (temp1)) == PLUS
1194 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1195 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1196 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1197 && ! side_effects_p (temp2)
1198 && ! may_trap_p (temp2)
1199 /* INSN must either branch to the insn after TEMP or the insn
1200 after TEMP must branch to the same place as INSN. */
1201 && (reallabelprev == temp
1202 || ((temp3 = next_active_insn (temp)) != 0
1203 && simplejump_p (temp3)
1204 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1205 && (temp3 = get_condition (insn, &temp4)) != 0
1206 /* We must be comparing objects whose modes imply the size.
1207 We could handle BLKmode if (1) emit_store_flag could
1208 and (2) we could find the size reliably. */
1209 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1210 && can_reverse_comparison_p (temp3, insn))
1212 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1213 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1217 /* It must be the case that TEMP2 is not modified in the range
1218 [TEMP4, INSN). The one exception we make is if the insn
1219 before INSN sets TEMP2 to something which is also unchanged
1220 in that range. In that case, we can move the initialization
1221 into our sequence. */
1223 if ((temp5 = prev_active_insn (insn)) != 0
1224 && no_labels_between_p (temp5, insn)
1225 && GET_CODE (temp5) == INSN
1226 && (temp6 = single_set (temp5)) != 0
1227 && rtx_equal_p (temp2, SET_DEST (temp6))
1228 && (CONSTANT_P (SET_SRC (temp6))
1229 || GET_CODE (SET_SRC (temp6)) == REG
1230 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1232 emit_insn (PATTERN (temp5));
1234 init = SET_SRC (temp6);
1237 if (CONSTANT_P (init)
1238 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1239 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1240 XEXP (temp3, 0), XEXP (temp3, 1),
1242 (code == LTU || code == LEU
1243 || code == GTU || code == GEU), 1);
1245 /* If we can do the store-flag, do the addition or
1249 target = expand_binop (GET_MODE (temp2),
1250 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1251 ? add_optab : sub_optab),
1252 temp2, target, temp2, 0, OPTAB_WIDEN);
1256 /* Put the result back in temp2 in case it isn't already.
1257 Then replace the jump, possible a CC0-setting insn in
1258 front of the jump, and TEMP, with the sequence we have
1261 if (target != temp2)
1262 emit_move_insn (temp2, target);
1267 emit_insns_before (seq, temp4);
1271 delete_insn (init_insn);
1273 next = NEXT_INSN (insn);
1275 delete_insn (prev_nonnote_insn (insn));
1281 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1282 old_max_reg = max_reg_num ();
1292 /* Simplify if (...) x = 1; else {...} if (x) ...
1293 We recognize this case scanning backwards as well.
1295 TEMP is the assignment to x;
1296 TEMP1 is the label at the head of the second if. */
1297 /* ?? This should call get_condition to find the values being
1298 compared, instead of looking for a COMPARE insn when HAVE_cc0
1299 is not defined. This would allow it to work on the m88k. */
1300 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1301 is not defined and the condition is tested by a separate compare
1302 insn. This is because the code below assumes that the result
1303 of the compare dies in the following branch.
1305 Not only that, but there might be other insns between the
1306 compare and branch whose results are live. Those insns need
1309 A way to fix this is to move the insns at JUMP_LABEL (insn)
1310 to before INSN. If we are running before flow, they will
1311 be deleted if they aren't needed. But this doesn't work
1314 This is really a special-case of jump threading, anyway. The
1315 right thing to do is to replace this and jump threading with
1316 much simpler code in cse.
1318 This code has been turned off in the non-cc0 case in the
1322 else if (this_is_simplejump
1323 /* Safe to skip USE and CLOBBER insns here
1324 since they will not be deleted. */
1325 && (temp = prev_active_insn (insn))
1326 && no_labels_between_p (temp, insn)
1327 && GET_CODE (temp) == INSN
1328 && GET_CODE (PATTERN (temp)) == SET
1329 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1330 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1331 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1332 /* If we find that the next value tested is `x'
1333 (TEMP1 is the insn where this happens), win. */
1334 && GET_CODE (temp1) == INSN
1335 && GET_CODE (PATTERN (temp1)) == SET
1337 /* Does temp1 `tst' the value of x? */
1338 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1339 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1340 && (temp1 = next_nonnote_insn (temp1))
1342 /* Does temp1 compare the value of x against zero? */
1343 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1344 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1345 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1346 == SET_DEST (PATTERN (temp)))
1347 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1348 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1350 && condjump_p (temp1))
1352 /* Get the if_then_else from the condjump. */
1353 rtx choice = SET_SRC (PATTERN (temp1));
1354 if (GET_CODE (choice) == IF_THEN_ELSE)
1356 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1357 rtx val = SET_SRC (PATTERN (temp));
1359 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1363 if (cond == const_true_rtx)
1364 ultimate = XEXP (choice, 1);
1365 else if (cond == const0_rtx)
1366 ultimate = XEXP (choice, 2);
1370 if (ultimate == pc_rtx)
1371 ultimate = get_label_after (temp1);
1372 else if (ultimate && GET_CODE (ultimate) != RETURN)
1373 ultimate = XEXP (ultimate, 0);
1375 if (ultimate && JUMP_LABEL(insn) != ultimate)
1376 changed |= redirect_jump (insn, ultimate);
1382 /* @@ This needs a bit of work before it will be right.
1384 Any type of comparison can be accepted for the first and
1385 second compare. When rewriting the first jump, we must
1386 compute the what conditions can reach label3, and use the
1387 appropriate code. We can not simply reverse/swap the code
1388 of the first jump. In some cases, the second jump must be
1392 < == converts to > ==
1393 < != converts to == >
1396 If the code is written to only accept an '==' test for the second
1397 compare, then all that needs to be done is to swap the condition
1398 of the first branch.
1400 It is questionable whether we want this optimization anyways,
1401 since if the user wrote code like this because he/she knew that
1402 the jump to label1 is taken most of the time, then rewriting
1403 this gives slower code. */
1404 /* @@ This should call get_condition to find the values being
1405 compared, instead of looking for a COMPARE insn when HAVE_cc0
1406 is not defined. This would allow it to work on the m88k. */
1407 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1408 is not defined and the condition is tested by a separate compare
1409 insn. This is because the code below assumes that the result
1410 of the compare dies in the following branch. */
1412 /* Simplify test a ~= b
1426 where ~= is an inequality, e.g. >, and ~~= is the swapped
1429 We recognize this case scanning backwards.
1431 TEMP is the conditional jump to `label2';
1432 TEMP1 is the test for `a == b';
1433 TEMP2 is the conditional jump to `label1';
1434 TEMP3 is the test for `a ~= b'. */
1435 else if (this_is_simplejump
1436 && (temp = prev_active_insn (insn))
1437 && no_labels_between_p (temp, insn)
1438 && condjump_p (temp)
1439 && (temp1 = prev_active_insn (temp))
1440 && no_labels_between_p (temp1, temp)
1441 && GET_CODE (temp1) == INSN
1442 && GET_CODE (PATTERN (temp1)) == SET
1444 && sets_cc0_p (PATTERN (temp1)) == 1
1446 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1447 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1448 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1450 && (temp2 = prev_active_insn (temp1))
1451 && no_labels_between_p (temp2, temp1)
1452 && condjump_p (temp2)
1453 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1454 && (temp3 = prev_active_insn (temp2))
1455 && no_labels_between_p (temp3, temp2)
1456 && GET_CODE (PATTERN (temp3)) == SET
1457 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1458 SET_DEST (PATTERN (temp1)))
1459 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1460 SET_SRC (PATTERN (temp3)))
1461 && ! inequality_comparisons_p (PATTERN (temp))
1462 && inequality_comparisons_p (PATTERN (temp2)))
1464 rtx fallthrough_label = JUMP_LABEL (temp2);
1466 ++LABEL_NUSES (fallthrough_label);
1467 if (swap_jump (temp2, JUMP_LABEL (insn)))
1473 if (--LABEL_NUSES (fallthrough_label) == 0)
1474 delete_insn (fallthrough_label);
1477 /* Simplify if (...) {... x = 1;} if (x) ...
1479 We recognize this case backwards.
1481 TEMP is the test of `x';
1482 TEMP1 is the assignment to `x' at the end of the
1483 previous statement. */
1484 /* @@ This should call get_condition to find the values being
1485 compared, instead of looking for a COMPARE insn when HAVE_cc0
1486 is not defined. This would allow it to work on the m88k. */
1487 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1488 is not defined and the condition is tested by a separate compare
1489 insn. This is because the code below assumes that the result
1490 of the compare dies in the following branch. */
1492 /* ??? This has to be turned off. The problem is that the
1493 unconditional jump might indirectly end up branching to the
1494 label between TEMP1 and TEMP. We can't detect this, in general,
1495 since it may become a jump to there after further optimizations.
1496 If that jump is done, it will be deleted, so we will retry
1497 this optimization in the next pass, thus an infinite loop.
1499 The present code prevents this by putting the jump after the
1500 label, but this is not logically correct. */
1502 else if (this_is_condjump
1503 /* Safe to skip USE and CLOBBER insns here
1504 since they will not be deleted. */
1505 && (temp = prev_active_insn (insn))
1506 && no_labels_between_p (temp, insn)
1507 && GET_CODE (temp) == INSN
1508 && GET_CODE (PATTERN (temp)) == SET
1510 && sets_cc0_p (PATTERN (temp)) == 1
1511 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1513 /* Temp must be a compare insn, we can not accept a register
1514 to register move here, since it may not be simply a
1516 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1517 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1518 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1519 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1520 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1522 /* May skip USE or CLOBBER insns here
1523 for checking for opportunity, since we
1524 take care of them later. */
1525 && (temp1 = prev_active_insn (temp))
1526 && GET_CODE (temp1) == INSN
1527 && GET_CODE (PATTERN (temp1)) == SET
1529 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1531 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1532 == SET_DEST (PATTERN (temp1)))
1534 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1535 /* If this isn't true, cse will do the job. */
1536 && ! no_labels_between_p (temp1, temp))
1538 /* Get the if_then_else from the condjump. */
1539 rtx choice = SET_SRC (PATTERN (insn));
1540 if (GET_CODE (choice) == IF_THEN_ELSE
1541 && (GET_CODE (XEXP (choice, 0)) == EQ
1542 || GET_CODE (XEXP (choice, 0)) == NE))
1544 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1549 /* Get the place that condjump will jump to
1550 if it is reached from here. */
1551 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1553 ultimate = XEXP (choice, 1);
1555 ultimate = XEXP (choice, 2);
1556 /* Get it as a CODE_LABEL. */
1557 if (ultimate == pc_rtx)
1558 ultimate = get_label_after (insn);
1560 /* Get the label out of the LABEL_REF. */
1561 ultimate = XEXP (ultimate, 0);
1563 /* Insert the jump immediately before TEMP, specifically
1564 after the label that is between TEMP1 and TEMP. */
1565 last_insn = PREV_INSN (temp);
1567 /* If we would be branching to the next insn, the jump
1568 would immediately be deleted and the re-inserted in
1569 a subsequent pass over the code. So don't do anything
1571 if (next_active_insn (last_insn)
1572 != next_active_insn (ultimate))
1574 emit_barrier_after (last_insn);
1575 p = emit_jump_insn_after (gen_jump (ultimate),
1577 JUMP_LABEL (p) = ultimate;
1578 ++LABEL_NUSES (ultimate);
1579 if (INSN_UID (ultimate) < max_jump_chain
1580 && INSN_CODE (p) < max_jump_chain)
1582 jump_chain[INSN_UID (p)]
1583 = jump_chain[INSN_UID (ultimate)];
1584 jump_chain[INSN_UID (ultimate)] = p;
1592 /* Detect a conditional jump going to the same place
1593 as an immediately following unconditional jump. */
1594 else if (this_is_condjump
1595 && (temp = next_active_insn (insn)) != 0
1596 && simplejump_p (temp)
1597 && (next_active_insn (JUMP_LABEL (insn))
1598 == next_active_insn (JUMP_LABEL (temp))))
1602 /* ??? Optional. Disables some optimizations, but makes
1603 gcov output more accurate with -O. */
1604 if (flag_test_coverage && !reload_completed)
1605 for (tem = insn; tem != temp; tem = NEXT_INSN (tem))
1606 if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0)
1617 /* Detect a conditional jump jumping over an unconditional trap. */
1619 && this_is_condjump && ! this_is_simplejump
1620 && reallabelprev != 0
1621 && GET_CODE (reallabelprev) == INSN
1622 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
1623 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
1624 && prev_active_insn (reallabelprev) == insn
1625 && no_labels_between_p (insn, reallabelprev)
1626 && (temp2 = get_condition (insn, &temp4))
1627 && can_reverse_comparison_p (temp2, insn))
1629 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
1630 XEXP (temp2, 0), XEXP (temp2, 1),
1631 TRAP_CODE (PATTERN (reallabelprev)));
1635 emit_insn_before (new, temp4);
1636 delete_insn (reallabelprev);
1642 /* Detect a jump jumping to an unconditional trap. */
1643 else if (HAVE_trap && this_is_condjump
1644 && (temp = next_active_insn (JUMP_LABEL (insn)))
1645 && GET_CODE (temp) == INSN
1646 && GET_CODE (PATTERN (temp)) == TRAP_IF
1647 && (this_is_simplejump
1648 || (temp2 = get_condition (insn, &temp4))))
1650 rtx tc = TRAP_CONDITION (PATTERN (temp));
1652 if (tc == const_true_rtx
1653 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
1656 /* Replace an unconditional jump to a trap with a trap. */
1657 if (this_is_simplejump)
1659 emit_barrier_after (emit_insn_before (gen_trap (), insn));
1664 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
1666 TRAP_CODE (PATTERN (temp)));
1669 emit_insn_before (new, temp4);
1675 /* If the trap condition and jump condition are mutually
1676 exclusive, redirect the jump to the following insn. */
1677 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
1678 && ! this_is_simplejump
1679 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
1680 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
1681 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
1682 && redirect_jump (insn, get_label_after (temp)))
1690 /* Detect a conditional jump jumping over an unconditional jump. */
1692 else if ((this_is_condjump || this_is_condjump_in_parallel)
1693 && ! this_is_simplejump
1694 && reallabelprev != 0
1695 && GET_CODE (reallabelprev) == JUMP_INSN
1696 && prev_active_insn (reallabelprev) == insn
1697 && no_labels_between_p (insn, reallabelprev)
1698 && simplejump_p (reallabelprev))
1700 /* When we invert the unconditional jump, we will be
1701 decrementing the usage count of its old label.
1702 Make sure that we don't delete it now because that
1703 might cause the following code to be deleted. */
1704 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1705 rtx prev_label = JUMP_LABEL (insn);
1708 ++LABEL_NUSES (prev_label);
1710 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1712 /* It is very likely that if there are USE insns before
1713 this jump, they hold REG_DEAD notes. These REG_DEAD
1714 notes are no longer valid due to this optimization,
1715 and will cause the life-analysis that following passes
1716 (notably delayed-branch scheduling) to think that
1717 these registers are dead when they are not.
1719 To prevent this trouble, we just remove the USE insns
1720 from the insn chain. */
1722 while (prev_uses && GET_CODE (prev_uses) == INSN
1723 && GET_CODE (PATTERN (prev_uses)) == USE)
1725 rtx useless = prev_uses;
1726 prev_uses = prev_nonnote_insn (prev_uses);
1727 delete_insn (useless);
1730 delete_insn (reallabelprev);
1735 /* We can now safely delete the label if it is unreferenced
1736 since the delete_insn above has deleted the BARRIER. */
1737 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1738 delete_insn (prev_label);
1743 /* Detect a jump to a jump. */
1745 nlabel = follow_jumps (JUMP_LABEL (insn));
1746 if (nlabel != JUMP_LABEL (insn)
1747 && redirect_jump (insn, nlabel))
1753 /* Look for if (foo) bar; else break; */
1754 /* The insns look like this:
1755 insn = condjump label1;
1756 ...range1 (some insns)...
1759 ...range2 (some insns)...
1760 jump somewhere unconditionally
1763 rtx label1 = next_label (insn);
1764 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1765 /* Don't do this optimization on the first round, so that
1766 jump-around-a-jump gets simplified before we ask here
1767 whether a jump is unconditional.
1769 Also don't do it when we are called after reload since
1770 it will confuse reorg. */
1772 && (reload_completed ? ! flag_delayed_branch : 1)
1773 /* Make sure INSN is something we can invert. */
1774 && condjump_p (insn)
1776 && JUMP_LABEL (insn) == label1
1777 && LABEL_NUSES (label1) == 1
1778 && GET_CODE (range1end) == JUMP_INSN
1779 && simplejump_p (range1end))
1781 rtx label2 = next_label (label1);
1782 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1783 if (range1end != range2end
1784 && JUMP_LABEL (range1end) == label2
1785 && GET_CODE (range2end) == JUMP_INSN
1786 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1787 /* Invert the jump condition, so we
1788 still execute the same insns in each case. */
1789 && invert_jump (insn, label1))
1791 rtx range1beg = next_active_insn (insn);
1792 rtx range2beg = next_active_insn (label1);
1793 rtx range1after, range2after;
1794 rtx range1before, range2before;
1797 /* Include in each range any notes before it, to be
1798 sure that we get the line number note if any, even
1799 if there are other notes here. */
1800 while (PREV_INSN (range1beg)
1801 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1802 range1beg = PREV_INSN (range1beg);
1804 while (PREV_INSN (range2beg)
1805 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1806 range2beg = PREV_INSN (range2beg);
1808 /* Don't move NOTEs for blocks or loops; shift them
1809 outside the ranges, where they'll stay put. */
1810 range1beg = squeeze_notes (range1beg, range1end);
1811 range2beg = squeeze_notes (range2beg, range2end);
1813 /* Get current surrounds of the 2 ranges. */
1814 range1before = PREV_INSN (range1beg);
1815 range2before = PREV_INSN (range2beg);
1816 range1after = NEXT_INSN (range1end);
1817 range2after = NEXT_INSN (range2end);
1819 /* Splice range2 where range1 was. */
1820 NEXT_INSN (range1before) = range2beg;
1821 PREV_INSN (range2beg) = range1before;
1822 NEXT_INSN (range2end) = range1after;
1823 PREV_INSN (range1after) = range2end;
1824 /* Splice range1 where range2 was. */
1825 NEXT_INSN (range2before) = range1beg;
1826 PREV_INSN (range1beg) = range2before;
1827 NEXT_INSN (range1end) = range2after;
1828 PREV_INSN (range2after) = range1end;
1830 /* Check for a loop end note between the end of
1831 range2, and the next code label. If there is one,
1832 then what we have really seen is
1833 if (foo) break; end_of_loop;
1834 and moved the break sequence outside the loop.
1835 We must move the LOOP_END note to where the
1836 loop really ends now, or we will confuse loop
1837 optimization. Stop if we find a LOOP_BEG note
1838 first, since we don't want to move the LOOP_END
1839 note in that case. */
1840 for (;range2after != label2; range2after = rangenext)
1842 rangenext = NEXT_INSN (range2after);
1843 if (GET_CODE (range2after) == NOTE)
1845 if (NOTE_LINE_NUMBER (range2after)
1846 == NOTE_INSN_LOOP_END)
1848 NEXT_INSN (PREV_INSN (range2after))
1850 PREV_INSN (rangenext)
1851 = PREV_INSN (range2after);
1852 PREV_INSN (range2after)
1853 = PREV_INSN (range1beg);
1854 NEXT_INSN (range2after) = range1beg;
1855 NEXT_INSN (PREV_INSN (range1beg))
1857 PREV_INSN (range1beg) = range2after;
1859 else if (NOTE_LINE_NUMBER (range2after)
1860 == NOTE_INSN_LOOP_BEG)
1870 /* Now that the jump has been tensioned,
1871 try cross jumping: check for identical code
1872 before the jump and before its target label. */
1874 /* First, cross jumping of conditional jumps: */
1876 if (cross_jump && condjump_p (insn))
1878 rtx newjpos, newlpos;
1879 rtx x = prev_real_insn (JUMP_LABEL (insn));
1881 /* A conditional jump may be crossjumped
1882 only if the place it jumps to follows
1883 an opposing jump that comes back here. */
1885 if (x != 0 && ! jump_back_p (x, insn))
1886 /* We have no opposing jump;
1887 cannot cross jump this insn. */
1891 /* TARGET is nonzero if it is ok to cross jump
1892 to code before TARGET. If so, see if matches. */
1894 find_cross_jump (insn, x, 2,
1895 &newjpos, &newlpos);
1899 do_cross_jump (insn, newjpos, newlpos);
1900 /* Make the old conditional jump
1901 into an unconditional one. */
1902 SET_SRC (PATTERN (insn))
1903 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
1904 INSN_CODE (insn) = -1;
1905 emit_barrier_after (insn);
1906 /* Add to jump_chain unless this is a new label
1907 whose UID is too large. */
1908 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1910 jump_chain[INSN_UID (insn)]
1911 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1912 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1919 /* Cross jumping of unconditional jumps:
1920 a few differences. */
1922 if (cross_jump && simplejump_p (insn))
1924 rtx newjpos, newlpos;
1929 /* TARGET is nonzero if it is ok to cross jump
1930 to code before TARGET. If so, see if matches. */
1931 find_cross_jump (insn, JUMP_LABEL (insn), 1,
1932 &newjpos, &newlpos);
1934 /* If cannot cross jump to code before the label,
1935 see if we can cross jump to another jump to
1937 /* Try each other jump to this label. */
1938 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
1939 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1940 target != 0 && newjpos == 0;
1941 target = jump_chain[INSN_UID (target)])
1943 && JUMP_LABEL (target) == JUMP_LABEL (insn)
1944 /* Ignore TARGET if it's deleted. */
1945 && ! INSN_DELETED_P (target))
1946 find_cross_jump (insn, target, 2,
1947 &newjpos, &newlpos);
1951 do_cross_jump (insn, newjpos, newlpos);
1957 /* This code was dead in the previous jump.c! */
1958 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
1960 /* Return insns all "jump to the same place"
1961 so we can cross-jump between any two of them. */
1963 rtx newjpos, newlpos, target;
1967 /* If cannot cross jump to code before the label,
1968 see if we can cross jump to another jump to
1970 /* Try each other jump to this label. */
1971 for (target = jump_chain[0];
1972 target != 0 && newjpos == 0;
1973 target = jump_chain[INSN_UID (target)])
1975 && ! INSN_DELETED_P (target)
1976 && GET_CODE (PATTERN (target)) == RETURN)
1977 find_cross_jump (insn, target, 2,
1978 &newjpos, &newlpos);
1982 do_cross_jump (insn, newjpos, newlpos);
1993 /* Delete extraneous line number notes.
1994 Note that two consecutive notes for different lines are not really
1995 extraneous. There should be some indication where that line belonged,
1996 even if it became empty. */
2001 for (insn = f; insn; insn = NEXT_INSN (insn))
2002 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2004 /* Delete this note if it is identical to previous note. */
2006 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2007 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2020 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2021 in front of it. If the machine allows it at this point (we might be
2022 after reload for a leaf routine), it will improve optimization for it
2023 to be there. We do this both here and at the start of this pass since
2024 the RETURN might have been deleted by some of our optimizations. */
2025 insn = get_last_insn ();
2026 while (insn && GET_CODE (insn) == NOTE)
2027 insn = PREV_INSN (insn);
2029 if (insn && GET_CODE (insn) != BARRIER)
2031 emit_jump_insn (gen_return ());
2037 can_reach_end = calculate_can_reach_end (last_insn, 0, 1);
2039 /* Show JUMP_CHAIN no longer valid. */
2043 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2044 notes whose labels don't occur in the insn any more. Returns the
2045 largest INSN_UID found. */
2050 int largest_uid = 0;
2053 for (insn = f; insn; insn = NEXT_INSN (insn))
2055 if (GET_CODE (insn) == CODE_LABEL)
2056 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
2057 else if (GET_CODE (insn) == JUMP_INSN)
2058 JUMP_LABEL (insn) = 0;
2059 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2063 for (note = REG_NOTES (insn); note; note = next)
2065 next = XEXP (note, 1);
2066 if (REG_NOTE_KIND (note) == REG_LABEL
2067 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
2068 remove_note (insn, note);
2071 if (INSN_UID (insn) > largest_uid)
2072 largest_uid = INSN_UID (insn);
2078 /* Delete insns following barriers, up to next label. */
2080 delete_barrier_successors (f)
2085 for (insn = f; insn;)
2087 if (GET_CODE (insn) == BARRIER)
2089 insn = NEXT_INSN (insn);
2090 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
2092 if (GET_CODE (insn) == NOTE
2093 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2094 insn = NEXT_INSN (insn);
2096 insn = delete_insn (insn);
2098 /* INSN is now the code_label. */
2101 insn = NEXT_INSN (insn);
2105 /* Mark the label each jump jumps to.
2106 Combine consecutive labels, and count uses of labels.
2108 For each label, make a chain (using `jump_chain')
2109 of all the *unconditional* jumps that jump to it;
2110 also make a chain of all returns.
2112 CROSS_JUMP indicates whether we are doing cross jumping
2113 and if we are whether we will be paying attention to
2114 death notes or not. */
2117 mark_all_labels (f, cross_jump)
2123 for (insn = f; insn; insn = NEXT_INSN (insn))
2124 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2126 mark_jump_label (PATTERN (insn), insn, cross_jump);
2127 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
2129 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2131 jump_chain[INSN_UID (insn)]
2132 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2133 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2135 if (GET_CODE (PATTERN (insn)) == RETURN)
2137 jump_chain[INSN_UID (insn)] = jump_chain[0];
2138 jump_chain[0] = insn;
2144 /* Delete all labels already not referenced.
2145 Also find and return the last insn. */
2148 delete_unreferenced_labels (f)
2151 rtx final = NULL_RTX;
2154 for (insn = f; insn; )
2156 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
2157 insn = delete_insn (insn);
2161 insn = NEXT_INSN (insn);
2168 /* Delete various simple forms of moves which have no necessary
2172 delete_noop_moves (f)
2177 for (insn = f; insn; )
2179 next = NEXT_INSN (insn);
2181 if (GET_CODE (insn) == INSN)
2183 register rtx body = PATTERN (insn);
2185 /* Combine stack_adjusts with following push_insns. */
2186 #ifdef PUSH_ROUNDING
2187 if (GET_CODE (body) == SET
2188 && SET_DEST (body) == stack_pointer_rtx
2189 && GET_CODE (SET_SRC (body)) == PLUS
2190 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
2191 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
2192 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
2195 rtx stack_adjust_insn = insn;
2196 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
2197 int total_pushed = 0;
2200 /* Find all successive push insns. */
2202 /* Don't convert more than three pushes;
2203 that starts adding too many displaced addresses
2204 and the whole thing starts becoming a losing
2209 p = next_nonnote_insn (p);
2210 if (p == 0 || GET_CODE (p) != INSN)
2212 pbody = PATTERN (p);
2213 if (GET_CODE (pbody) != SET)
2215 dest = SET_DEST (pbody);
2216 /* Allow a no-op move between the adjust and the push. */
2217 if (GET_CODE (dest) == REG
2218 && GET_CODE (SET_SRC (pbody)) == REG
2219 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2221 if (! (GET_CODE (dest) == MEM
2222 && GET_CODE (XEXP (dest, 0)) == POST_INC
2223 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2226 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
2227 > stack_adjust_amount)
2229 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2232 /* Discard the amount pushed from the stack adjust;
2233 maybe eliminate it entirely. */
2234 if (total_pushed >= stack_adjust_amount)
2236 delete_computation (stack_adjust_insn);
2237 total_pushed = stack_adjust_amount;
2240 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
2241 = GEN_INT (stack_adjust_amount - total_pushed);
2243 /* Change the appropriate push insns to ordinary stores. */
2245 while (total_pushed > 0)
2248 p = next_nonnote_insn (p);
2249 if (GET_CODE (p) != INSN)
2251 pbody = PATTERN (p);
2252 if (GET_CODE (pbody) != SET)
2254 dest = SET_DEST (pbody);
2255 /* Allow a no-op move between the adjust and the push. */
2256 if (GET_CODE (dest) == REG
2257 && GET_CODE (SET_SRC (pbody)) == REG
2258 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2260 if (! (GET_CODE (dest) == MEM
2261 && GET_CODE (XEXP (dest, 0)) == POST_INC
2262 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2264 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2265 /* If this push doesn't fully fit in the space
2266 of the stack adjust that we deleted,
2267 make another stack adjust here for what we
2268 didn't use up. There should be peepholes
2269 to recognize the resulting sequence of insns. */
2270 if (total_pushed < 0)
2272 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
2273 GEN_INT (- total_pushed)),
2278 = plus_constant (stack_pointer_rtx, total_pushed);
2283 /* Detect and delete no-op move instructions
2284 resulting from not allocating a parameter in a register. */
2286 if (GET_CODE (body) == SET
2287 && (SET_DEST (body) == SET_SRC (body)
2288 || (GET_CODE (SET_DEST (body)) == MEM
2289 && GET_CODE (SET_SRC (body)) == MEM
2290 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
2291 && ! (GET_CODE (SET_DEST (body)) == MEM
2292 && MEM_VOLATILE_P (SET_DEST (body)))
2293 && ! (GET_CODE (SET_SRC (body)) == MEM
2294 && MEM_VOLATILE_P (SET_SRC (body))))
2295 delete_computation (insn);
2297 /* Detect and ignore no-op move instructions
2298 resulting from smart or fortuitous register allocation. */
2300 else if (GET_CODE (body) == SET)
2302 int sreg = true_regnum (SET_SRC (body));
2303 int dreg = true_regnum (SET_DEST (body));
2305 if (sreg == dreg && sreg >= 0)
2307 else if (sreg >= 0 && dreg >= 0)
2310 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
2311 sreg, NULL_PTR, dreg,
2312 GET_MODE (SET_SRC (body)));
2315 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
2317 /* DREG may have been the target of a REG_DEAD note in
2318 the insn which makes INSN redundant. If so, reorg
2319 would still think it is dead. So search for such a
2320 note and delete it if we find it. */
2321 if (! find_regno_note (insn, REG_UNUSED, dreg))
2322 for (trial = prev_nonnote_insn (insn);
2323 trial && GET_CODE (trial) != CODE_LABEL;
2324 trial = prev_nonnote_insn (trial))
2325 if (find_regno_note (trial, REG_DEAD, dreg))
2327 remove_death (dreg, trial);
2331 /* Deleting insn could lose a death-note for SREG. */
2332 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
2334 /* Change this into a USE so that we won't emit
2335 code for it, but still can keep the note. */
2337 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
2338 INSN_CODE (insn) = -1;
2339 /* Remove all reg notes but the REG_DEAD one. */
2340 REG_NOTES (insn) = trial;
2341 XEXP (trial, 1) = NULL_RTX;
2347 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
2348 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
2350 GET_MODE (SET_DEST (body))))
2352 /* This handles the case where we have two consecutive
2353 assignments of the same constant to pseudos that didn't
2354 get a hard reg. Each SET from the constant will be
2355 converted into a SET of the spill register and an
2356 output reload will be made following it. This produces
2357 two loads of the same constant into the same spill
2362 /* Look back for a death note for the first reg.
2363 If there is one, it is no longer accurate. */
2364 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
2366 if ((GET_CODE (in_insn) == INSN
2367 || GET_CODE (in_insn) == JUMP_INSN)
2368 && find_regno_note (in_insn, REG_DEAD, dreg))
2370 remove_death (dreg, in_insn);
2373 in_insn = PREV_INSN (in_insn);
2376 /* Delete the second load of the value. */
2380 else if (GET_CODE (body) == PARALLEL)
2382 /* If each part is a set between two identical registers or
2383 a USE or CLOBBER, delete the insn. */
2387 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
2389 tem = XVECEXP (body, 0, i);
2390 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
2393 if (GET_CODE (tem) != SET
2394 || (sreg = true_regnum (SET_SRC (tem))) < 0
2395 || (dreg = true_regnum (SET_DEST (tem))) < 0
2403 /* Also delete insns to store bit fields if they are no-ops. */
2404 /* Not worth the hair to detect this in the big-endian case. */
2405 else if (! BYTES_BIG_ENDIAN
2406 && GET_CODE (body) == SET
2407 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
2408 && XEXP (SET_DEST (body), 2) == const0_rtx
2409 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
2410 && ! (GET_CODE (SET_SRC (body)) == MEM
2411 && MEM_VOLATILE_P (SET_SRC (body))))
2418 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2419 If so indicate that this function can drop off the end by returning
2422 CHECK_DELETED indicates whether we must check if the note being
2423 searched for has the deleted flag set.
2425 DELETE_FINAL_NOTE indicates whether we should delete the note
2429 calculate_can_reach_end (last, check_deleted, delete_final_note)
2432 int delete_final_note;
2437 while (insn != NULL_RTX)
2441 /* One label can follow the end-note: the return label. */
2442 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2444 /* Ordinary insns can follow it if returning a structure. */
2445 else if (GET_CODE (insn) == INSN)
2447 /* If machine uses explicit RETURN insns, no epilogue,
2448 then one of them follows the note. */
2449 else if (GET_CODE (insn) == JUMP_INSN
2450 && GET_CODE (PATTERN (insn)) == RETURN)
2452 /* A barrier can follow the return insn. */
2453 else if (GET_CODE (insn) == BARRIER)
2455 /* Other kinds of notes can follow also. */
2456 else if (GET_CODE (insn) == NOTE
2457 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2463 insn = PREV_INSN (insn);
2466 /* See if we backed up to the appropriate type of note. */
2467 if (insn != NULL_RTX
2468 && GET_CODE (insn) == NOTE
2469 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
2470 && (check_deleted == 0
2471 || ! INSN_DELETED_P (insn)))
2473 if (delete_final_note)
2481 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2482 jump. Assume that this unconditional jump is to the exit test code. If
2483 the code is sufficiently simple, make a copy of it before INSN,
2484 followed by a jump to the exit of the loop. Then delete the unconditional
2487 Return 1 if we made the change, else 0.
2489 This is only safe immediately after a regscan pass because it uses the
2490 values of regno_first_uid and regno_last_uid. */
2493 duplicate_loop_exit_test (loop_start)
2496 rtx insn, set, reg, p, link;
2499 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2501 int max_reg = max_reg_num ();
2504 /* Scan the exit code. We do not perform this optimization if any insn:
2508 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2509 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2510 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2513 We also do not do this if we find an insn with ASM_OPERANDS. While
2514 this restriction should not be necessary, copying an insn with
2515 ASM_OPERANDS can confuse asm_noperands in some cases.
2517 Also, don't do this if the exit code is more than 20 insns. */
2519 for (insn = exitcode;
2521 && ! (GET_CODE (insn) == NOTE
2522 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2523 insn = NEXT_INSN (insn))
2525 switch (GET_CODE (insn))
2531 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2532 a jump immediately after the loop start that branches outside
2533 the loop but within an outer loop, near the exit test.
2534 If we copied this exit test and created a phony
2535 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2536 before the exit test look like these could be safely moved
2537 out of the loop even if they actually may be never executed.
2538 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2540 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2541 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2545 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2546 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
2547 /* If we were to duplicate this code, we would not move
2548 the BLOCK notes, and so debugging the moved code would
2549 be difficult. Thus, we only move the code with -O2 or
2556 /* The code below would grossly mishandle REG_WAS_0 notes,
2557 so get rid of them here. */
2558 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
2559 remove_note (insn, p);
2560 if (++num_insns > 20
2561 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2562 || find_reg_note (insn, REG_LIBCALL, NULL_RTX)
2563 || asm_noperands (PATTERN (insn)) > 0)
2571 /* Unless INSN is zero, we can do the optimization. */
2577 /* See if any insn sets a register only used in the loop exit code and
2578 not a user variable. If so, replace it with a new register. */
2579 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2580 if (GET_CODE (insn) == INSN
2581 && (set = single_set (insn)) != 0
2582 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2583 || (GET_CODE (reg) == SUBREG
2584 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2585 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2586 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2588 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2589 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2594 /* We can do the replacement. Allocate reg_map if this is the
2595 first replacement we found. */
2598 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2599 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2602 REG_LOOP_TEST_P (reg) = 1;
2604 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2608 /* Now copy each insn. */
2609 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2610 switch (GET_CODE (insn))
2613 copy = emit_barrier_before (loop_start);
2616 /* Only copy line-number notes. */
2617 if (NOTE_LINE_NUMBER (insn) >= 0)
2619 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2620 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2625 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2627 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2629 mark_jump_label (PATTERN (copy), copy, 0);
2631 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2633 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2634 if (REG_NOTE_KIND (link) != REG_LABEL)
2636 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2639 if (reg_map && REG_NOTES (copy))
2640 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2644 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2646 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2647 mark_jump_label (PATTERN (copy), copy, 0);
2648 if (REG_NOTES (insn))
2650 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2652 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2655 /* If this is a simple jump, add it to the jump chain. */
2657 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2658 && simplejump_p (copy))
2660 jump_chain[INSN_UID (copy)]
2661 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2662 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2670 /* Now clean up by emitting a jump to the end label and deleting the jump
2671 at the start of the loop. */
2672 if (! copy || GET_CODE (copy) != BARRIER)
2674 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2676 mark_jump_label (PATTERN (copy), copy, 0);
2677 if (INSN_UID (copy) < max_jump_chain
2678 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2680 jump_chain[INSN_UID (copy)]
2681 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2682 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2684 emit_barrier_before (loop_start);
2687 /* Mark the exit code as the virtual top of the converted loop. */
2688 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2690 delete_insn (next_nonnote_insn (loop_start));
2695 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2696 loop-end notes between START and END out before START. Assume that
2697 END is not such a note. START may be such a note. Returns the value
2698 of the new starting insn, which may be different if the original start
2702 squeeze_notes (start, end)
2708 for (insn = start; insn != end; insn = next)
2710 next = NEXT_INSN (insn);
2711 if (GET_CODE (insn) == NOTE
2712 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2713 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2714 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2715 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2716 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2717 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2723 rtx prev = PREV_INSN (insn);
2724 PREV_INSN (insn) = PREV_INSN (start);
2725 NEXT_INSN (insn) = start;
2726 NEXT_INSN (PREV_INSN (insn)) = insn;
2727 PREV_INSN (NEXT_INSN (insn)) = insn;
2728 NEXT_INSN (prev) = next;
2729 PREV_INSN (next) = prev;
2737 /* Compare the instructions before insn E1 with those before E2
2738 to find an opportunity for cross jumping.
2739 (This means detecting identical sequences of insns followed by
2740 jumps to the same place, or followed by a label and a jump
2741 to that label, and replacing one with a jump to the other.)
2743 Assume E1 is a jump that jumps to label E2
2744 (that is not always true but it might as well be).
2745 Find the longest possible equivalent sequences
2746 and store the first insns of those sequences into *F1 and *F2.
2747 Store zero there if no equivalent preceding instructions are found.
2749 We give up if we find a label in stream 1.
2750 Actually we could transfer that label into stream 2. */
2753 find_cross_jump (e1, e2, minimum, f1, f2)
2758 register rtx i1 = e1, i2 = e2;
2759 register rtx p1, p2;
2762 rtx last1 = 0, last2 = 0;
2763 rtx afterlast1 = 0, afterlast2 = 0;
2770 i1 = prev_nonnote_insn (i1);
2772 i2 = PREV_INSN (i2);
2773 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2774 i2 = PREV_INSN (i2);
2779 /* Don't allow the range of insns preceding E1 or E2
2780 to include the other (E2 or E1). */
2781 if (i2 == e1 || i1 == e2)
2784 /* If we will get to this code by jumping, those jumps will be
2785 tensioned to go directly to the new label (before I2),
2786 so this cross-jumping won't cost extra. So reduce the minimum. */
2787 if (GET_CODE (i1) == CODE_LABEL)
2793 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2796 /* Avoid moving insns across EH regions if either of the insns
2799 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
2800 && !in_same_eh_region (i1, i2))
2806 /* If this is a CALL_INSN, compare register usage information.
2807 If we don't check this on stack register machines, the two
2808 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2809 numbers of stack registers in the same basic block.
2810 If we don't check this on machines with delay slots, a delay slot may
2811 be filled that clobbers a parameter expected by the subroutine.
2813 ??? We take the simple route for now and assume that if they're
2814 equal, they were constructed identically. */
2816 if (GET_CODE (i1) == CALL_INSN
2817 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2818 CALL_INSN_FUNCTION_USAGE (i2)))
2822 /* If cross_jump_death_matters is not 0, the insn's mode
2823 indicates whether or not the insn contains any stack-like
2826 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2828 /* If register stack conversion has already been done, then
2829 death notes must also be compared before it is certain that
2830 the two instruction streams match. */
2833 HARD_REG_SET i1_regset, i2_regset;
2835 CLEAR_HARD_REG_SET (i1_regset);
2836 CLEAR_HARD_REG_SET (i2_regset);
2838 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2839 if (REG_NOTE_KIND (note) == REG_DEAD
2840 && STACK_REG_P (XEXP (note, 0)))
2841 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2843 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2844 if (REG_NOTE_KIND (note) == REG_DEAD
2845 && STACK_REG_P (XEXP (note, 0)))
2846 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2848 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2857 /* Don't allow old-style asm or volatile extended asms to be accepted
2858 for cross jumping purposes. It is conceptually correct to allow
2859 them, since cross-jumping preserves the dynamic instruction order
2860 even though it is changing the static instruction order. However,
2861 if an asm is being used to emit an assembler pseudo-op, such as
2862 the MIPS `.set reorder' pseudo-op, then the static instruction order
2863 matters and it must be preserved. */
2864 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
2865 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
2866 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
2869 if (lose || GET_CODE (p1) != GET_CODE (p2)
2870 || ! rtx_renumbered_equal_p (p1, p2))
2872 /* The following code helps take care of G++ cleanups. */
2876 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2877 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2878 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2879 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2880 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2881 /* If the equivalences are not to a constant, they may
2882 reference pseudos that no longer exist, so we can't
2884 && CONSTANT_P (XEXP (equiv1, 0))
2885 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2887 rtx s1 = single_set (i1);
2888 rtx s2 = single_set (i2);
2889 if (s1 != 0 && s2 != 0
2890 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2892 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2893 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2894 if (! rtx_renumbered_equal_p (p1, p2))
2896 else if (apply_change_group ())
2901 /* Insns fail to match; cross jumping is limited to the following
2905 /* Don't allow the insn after a compare to be shared by
2906 cross-jumping unless the compare is also shared.
2907 Here, if either of these non-matching insns is a compare,
2908 exclude the following insn from possible cross-jumping. */
2909 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2910 last1 = afterlast1, last2 = afterlast2, ++minimum;
2913 /* If cross-jumping here will feed a jump-around-jump
2914 optimization, this jump won't cost extra, so reduce
2916 if (GET_CODE (i1) == JUMP_INSN
2918 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2924 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2926 /* Ok, this insn is potentially includable in a cross-jump here. */
2927 afterlast1 = last1, afterlast2 = last2;
2928 last1 = i1, last2 = i2, --minimum;
2932 if (minimum <= 0 && last1 != 0 && last1 != e1)
2933 *f1 = last1, *f2 = last2;
2937 do_cross_jump (insn, newjpos, newlpos)
2938 rtx insn, newjpos, newlpos;
2940 /* Find an existing label at this point
2941 or make a new one if there is none. */
2942 register rtx label = get_label_before (newlpos);
2944 /* Make the same jump insn jump to the new point. */
2945 if (GET_CODE (PATTERN (insn)) == RETURN)
2947 /* Remove from jump chain of returns. */
2948 delete_from_jump_chain (insn);
2949 /* Change the insn. */
2950 PATTERN (insn) = gen_jump (label);
2951 INSN_CODE (insn) = -1;
2952 JUMP_LABEL (insn) = label;
2953 LABEL_NUSES (label)++;
2954 /* Add to new the jump chain. */
2955 if (INSN_UID (label) < max_jump_chain
2956 && INSN_UID (insn) < max_jump_chain)
2958 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2959 jump_chain[INSN_UID (label)] = insn;
2963 redirect_jump (insn, label);
2965 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2966 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2967 the NEWJPOS stream. */
2969 while (newjpos != insn)
2973 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2974 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2975 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2976 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2977 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2978 remove_note (newlpos, lnote);
2980 delete_insn (newjpos);
2981 newjpos = next_real_insn (newjpos);
2982 newlpos = next_real_insn (newlpos);
2986 /* Return the label before INSN, or put a new label there. */
2989 get_label_before (insn)
2994 /* Find an existing label at this point
2995 or make a new one if there is none. */
2996 label = prev_nonnote_insn (insn);
2998 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3000 rtx prev = PREV_INSN (insn);
3002 label = gen_label_rtx ();
3003 emit_label_after (label, prev);
3004 LABEL_NUSES (label) = 0;
3009 /* Return the label after INSN, or put a new label there. */
3012 get_label_after (insn)
3017 /* Find an existing label at this point
3018 or make a new one if there is none. */
3019 label = next_nonnote_insn (insn);
3021 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3023 label = gen_label_rtx ();
3024 emit_label_after (label, insn);
3025 LABEL_NUSES (label) = 0;
3030 /* Return 1 if INSN is a jump that jumps to right after TARGET
3031 only on the condition that TARGET itself would drop through.
3032 Assumes that TARGET is a conditional jump. */
3035 jump_back_p (insn, target)
3039 enum rtx_code codei, codet;
3041 if (simplejump_p (insn) || ! condjump_p (insn)
3042 || simplejump_p (target)
3043 || target != prev_real_insn (JUMP_LABEL (insn)))
3046 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
3047 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
3049 codei = GET_CODE (cinsn);
3050 codet = GET_CODE (ctarget);
3052 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
3054 if (! can_reverse_comparison_p (cinsn, insn))
3056 codei = reverse_condition (codei);
3059 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
3061 if (! can_reverse_comparison_p (ctarget, target))
3063 codet = reverse_condition (codet);
3066 return (codei == codet
3067 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
3068 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
3071 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3072 return non-zero if it is safe to reverse this comparison. It is if our
3073 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3074 this is known to be an integer comparison. */
3077 can_reverse_comparison_p (comparison, insn)
3083 /* If this is not actually a comparison, we can't reverse it. */
3084 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
3087 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3088 /* If this is an NE comparison, it is safe to reverse it to an EQ
3089 comparison and vice versa, even for floating point. If no operands
3090 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3091 always false and NE is always true, so the reversal is also valid. */
3093 || GET_CODE (comparison) == NE
3094 || GET_CODE (comparison) == EQ)
3097 arg0 = XEXP (comparison, 0);
3099 /* Make sure ARG0 is one of the actual objects being compared. If we
3100 can't do this, we can't be sure the comparison can be reversed.
3102 Handle cc0 and a MODE_CC register. */
3103 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
3109 rtx prev = prev_nonnote_insn (insn);
3110 rtx set = single_set (prev);
3112 if (set == 0 || SET_DEST (set) != arg0)
3115 arg0 = SET_SRC (set);
3117 if (GET_CODE (arg0) == COMPARE)
3118 arg0 = XEXP (arg0, 0);
3121 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3122 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3123 return (GET_CODE (arg0) == CONST_INT
3124 || (GET_MODE (arg0) != VOIDmode
3125 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
3126 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
3129 /* Given an rtx-code for a comparison, return the code
3130 for the negated comparison.
3131 WATCH OUT! reverse_condition is not safe to use on a jump
3132 that might be acting on the results of an IEEE floating point comparison,
3133 because of the special treatment of non-signaling nans in comparisons.
3134 Use can_reverse_comparison_p to be sure. */
3137 reverse_condition (code)
3178 /* Similar, but return the code when two operands of a comparison are swapped.
3179 This IS safe for IEEE floating-point. */
3182 swap_condition (code)
3221 /* Given a comparison CODE, return the corresponding unsigned comparison.
3222 If CODE is an equality comparison or already an unsigned comparison,
3223 CODE is returned. */
3226 unsigned_condition (code)
3256 /* Similarly, return the signed version of a comparison. */
3259 signed_condition (code)
3289 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3290 truth of CODE1 implies the truth of CODE2. */
3293 comparison_dominates_p (code1, code2)
3294 enum rtx_code code1, code2;
3302 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3307 if (code2 == LE || code2 == NE)
3312 if (code2 == GE || code2 == NE)
3317 if (code2 == LEU || code2 == NE)
3322 if (code2 == GEU || code2 == NE)
3333 /* Return 1 if INSN is an unconditional jump and nothing else. */
3339 return (GET_CODE (insn) == JUMP_INSN
3340 && GET_CODE (PATTERN (insn)) == SET
3341 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3342 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3345 /* Return nonzero if INSN is a (possibly) conditional jump
3346 and nothing more. */
3352 register rtx x = PATTERN (insn);
3353 if (GET_CODE (x) != SET)
3355 if (GET_CODE (SET_DEST (x)) != PC)
3357 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3359 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3361 if (XEXP (SET_SRC (x), 2) == pc_rtx
3362 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3363 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3365 if (XEXP (SET_SRC (x), 1) == pc_rtx
3366 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3367 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3372 /* Return nonzero if INSN is a (possibly) conditional jump
3373 and nothing more. */
3376 condjump_in_parallel_p (insn)
3379 register rtx x = PATTERN (insn);
3381 if (GET_CODE (x) != PARALLEL)
3384 x = XVECEXP (x, 0, 0);
3386 if (GET_CODE (x) != SET)
3388 if (GET_CODE (SET_DEST (x)) != PC)
3390 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3392 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3394 if (XEXP (SET_SRC (x), 2) == pc_rtx
3395 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3396 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3398 if (XEXP (SET_SRC (x), 1) == pc_rtx
3399 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3400 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3407 /* Return 1 if X is an RTX that does nothing but set the condition codes
3408 and CLOBBER or USE registers.
3409 Return -1 if X does explicitly set the condition codes,
3410 but also does other things. */
3414 rtx x ATTRIBUTE_UNUSED;
3416 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3418 if (GET_CODE (x) == PARALLEL)
3422 int other_things = 0;
3423 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3425 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3426 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3428 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3431 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3437 /* Follow any unconditional jump at LABEL;
3438 return the ultimate label reached by any such chain of jumps.
3439 If LABEL is not followed by a jump, return LABEL.
3440 If the chain loops or we can't find end, return LABEL,
3441 since that tells caller to avoid changing the insn.
3443 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3444 a USE or CLOBBER. */
3447 follow_jumps (label)
3452 register rtx value = label;
3457 && (insn = next_active_insn (value)) != 0
3458 && GET_CODE (insn) == JUMP_INSN
3459 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3460 || GET_CODE (PATTERN (insn)) == RETURN)
3461 && (next = NEXT_INSN (insn))
3462 && GET_CODE (next) == BARRIER);
3465 /* Don't chain through the insn that jumps into a loop
3466 from outside the loop,
3467 since that would create multiple loop entry jumps
3468 and prevent loop optimization. */
3470 if (!reload_completed)
3471 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3472 if (GET_CODE (tem) == NOTE
3473 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3474 /* ??? Optional. Disables some optimizations, but makes
3475 gcov output more accurate with -O. */
3476 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3479 /* If we have found a cycle, make the insn jump to itself. */
3480 if (JUMP_LABEL (insn) == label)
3483 tem = next_active_insn (JUMP_LABEL (insn));
3484 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3485 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3488 value = JUMP_LABEL (insn);
3495 /* Assuming that field IDX of X is a vector of label_refs,
3496 replace each of them by the ultimate label reached by it.
3497 Return nonzero if a change is made.
3498 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3501 tension_vector_labels (x, idx)
3507 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3509 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3510 register rtx nlabel = follow_jumps (olabel);
3511 if (nlabel && nlabel != olabel)
3513 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3514 ++LABEL_NUSES (nlabel);
3515 if (--LABEL_NUSES (olabel) == 0)
3516 delete_insn (olabel);
3523 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3524 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3525 in INSN, then store one of them in JUMP_LABEL (INSN).
3526 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3527 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3528 Also, when there are consecutive labels, canonicalize on the last of them.
3530 Note that two labels separated by a loop-beginning note
3531 must be kept distinct if we have not yet done loop-optimization,
3532 because the gap between them is where loop-optimize
3533 will want to move invariant code to. CROSS_JUMP tells us
3534 that loop-optimization is done with.
3536 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3537 two labels distinct if they are separated by only USE or CLOBBER insns. */
3540 mark_jump_label (x, insn, cross_jump)
3545 register RTX_CODE code = GET_CODE (x);
3563 /* If this is a constant-pool reference, see if it is a label. */
3564 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3565 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3566 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3571 rtx label = XEXP (x, 0);
3576 if (GET_CODE (label) != CODE_LABEL)
3579 /* Ignore references to labels of containing functions. */
3580 if (LABEL_REF_NONLOCAL_P (x))
3583 /* If there are other labels following this one,
3584 replace it with the last of the consecutive labels. */
3585 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3587 if (GET_CODE (next) == CODE_LABEL)
3589 else if (cross_jump && GET_CODE (next) == INSN
3590 && (GET_CODE (PATTERN (next)) == USE
3591 || GET_CODE (PATTERN (next)) == CLOBBER))
3593 else if (GET_CODE (next) != NOTE)
3595 else if (! cross_jump
3596 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3597 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3598 /* ??? Optional. Disables some optimizations, but
3599 makes gcov output more accurate with -O. */
3600 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3604 XEXP (x, 0) = label;
3605 if (! insn || ! INSN_DELETED_P (insn))
3606 ++LABEL_NUSES (label);
3610 if (GET_CODE (insn) == JUMP_INSN)
3611 JUMP_LABEL (insn) = label;
3613 /* If we've changed OLABEL and we had a REG_LABEL note
3614 for it, update it as well. */
3615 else if (label != olabel
3616 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3617 XEXP (note, 0) = label;
3619 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3621 else if (! find_reg_note (insn, REG_LABEL, label))
3623 /* This code used to ignore labels which refered to dispatch
3624 tables to avoid flow.c generating worse code.
3626 However, in the presense of global optimizations like
3627 gcse which call find_basic_blocks without calling
3628 life_analysis, not recording such labels will lead
3629 to compiler aborts because of inconsistencies in the
3630 flow graph. So we go ahead and record the label.
3632 It may also be the case that the optimization argument
3633 is no longer valid because of the more accurate cfg
3634 we build in find_basic_blocks -- it no longer pessimizes
3635 code when it finds a REG_LABEL note. */
3636 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
3643 /* Do walk the labels in a vector, but not the first operand of an
3644 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3647 if (! INSN_DELETED_P (insn))
3649 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3651 for (i = 0; i < XVECLEN (x, eltnum); i++)
3652 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3660 fmt = GET_RTX_FORMAT (code);
3661 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3664 mark_jump_label (XEXP (x, i), insn, cross_jump);
3665 else if (fmt[i] == 'E')
3668 for (j = 0; j < XVECLEN (x, i); j++)
3669 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3674 /* If all INSN does is set the pc, delete it,
3675 and delete the insn that set the condition codes for it
3676 if that's what the previous thing was. */
3682 register rtx set = single_set (insn);
3684 if (set && GET_CODE (SET_DEST (set)) == PC)
3685 delete_computation (insn);
3688 /* Delete INSN and recursively delete insns that compute values used only
3689 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3690 If we are running before flow.c, we need do nothing since flow.c will
3691 delete dead code. We also can't know if the registers being used are
3692 dead or not at this point.
3694 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3695 nothing other than set a register that dies in this insn, we can delete
3698 On machines with CC0, if CC0 is used in this insn, we may be able to
3699 delete the insn that set it. */
3702 delete_computation (insn)
3708 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3710 rtx prev = prev_nonnote_insn (insn);
3711 /* We assume that at this stage
3712 CC's are always set explicitly
3713 and always immediately before the jump that
3714 will use them. So if the previous insn
3715 exists to set the CC's, delete it
3716 (unless it performs auto-increments, etc.). */
3717 if (prev && GET_CODE (prev) == INSN
3718 && sets_cc0_p (PATTERN (prev)))
3720 if (sets_cc0_p (PATTERN (prev)) > 0
3721 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3722 delete_computation (prev);
3724 /* Otherwise, show that cc0 won't be used. */
3725 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
3726 cc0_rtx, REG_NOTES (prev));
3731 for (note = REG_NOTES (insn); note; note = next)
3735 next = XEXP (note, 1);
3737 if (REG_NOTE_KIND (note) != REG_DEAD
3738 /* Verify that the REG_NOTE is legitimate. */
3739 || GET_CODE (XEXP (note, 0)) != REG)
3742 for (our_prev = prev_nonnote_insn (insn);
3743 our_prev && GET_CODE (our_prev) == INSN;
3744 our_prev = prev_nonnote_insn (our_prev))
3746 /* If we reach a SEQUENCE, it is too complex to try to
3747 do anything with it, so give up. */
3748 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3751 if (GET_CODE (PATTERN (our_prev)) == USE
3752 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3753 /* reorg creates USEs that look like this. We leave them
3754 alone because reorg needs them for its own purposes. */
3757 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3759 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3762 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3764 /* If we find a SET of something else, we can't
3769 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3771 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3773 if (GET_CODE (part) == SET
3774 && SET_DEST (part) != XEXP (note, 0))
3778 if (i == XVECLEN (PATTERN (our_prev), 0))
3779 delete_computation (our_prev);
3781 else if (GET_CODE (PATTERN (our_prev)) == SET
3782 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3783 delete_computation (our_prev);
3788 /* If OUR_PREV references the register that dies here, it is an
3789 additional use. Hence any prior SET isn't dead. However, this
3790 insn becomes the new place for the REG_DEAD note. */
3791 if (reg_overlap_mentioned_p (XEXP (note, 0),
3792 PATTERN (our_prev)))
3794 XEXP (note, 1) = REG_NOTES (our_prev);
3795 REG_NOTES (our_prev) = note;
3804 /* Delete insn INSN from the chain of insns and update label ref counts.
3805 May delete some following insns as a consequence; may even delete
3806 a label elsewhere and insns that follow it.
3808 Returns the first insn after INSN that was not deleted. */
3814 register rtx next = NEXT_INSN (insn);
3815 register rtx prev = PREV_INSN (insn);
3816 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3817 register int dont_really_delete = 0;
3819 while (next && INSN_DELETED_P (next))
3820 next = NEXT_INSN (next);
3822 /* This insn is already deleted => return first following nondeleted. */
3823 if (INSN_DELETED_P (insn))
3826 /* Don't delete user-declared labels. Convert them to special NOTEs
3828 if (was_code_label && LABEL_NAME (insn) != 0
3829 && optimize && ! dont_really_delete)
3831 PUT_CODE (insn, NOTE);
3832 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3833 NOTE_SOURCE_FILE (insn) = 0;
3834 dont_really_delete = 1;
3837 /* Mark this insn as deleted. */
3838 INSN_DELETED_P (insn) = 1;
3840 /* If this is an unconditional jump, delete it from the jump chain. */
3841 if (simplejump_p (insn))
3842 delete_from_jump_chain (insn);
3844 /* If instruction is followed by a barrier,
3845 delete the barrier too. */
3847 if (next != 0 && GET_CODE (next) == BARRIER)
3849 INSN_DELETED_P (next) = 1;
3850 next = NEXT_INSN (next);
3853 /* Patch out INSN (and the barrier if any) */
3855 if (optimize && ! dont_really_delete)
3859 NEXT_INSN (prev) = next;
3860 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3861 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3862 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3867 PREV_INSN (next) = prev;
3868 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3869 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3872 if (prev && NEXT_INSN (prev) == 0)
3873 set_last_insn (prev);
3876 /* If deleting a jump, decrement the count of the label,
3877 and delete the label if it is now unused. */
3879 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3880 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3882 /* This can delete NEXT or PREV,
3883 either directly if NEXT is JUMP_LABEL (INSN),
3884 or indirectly through more levels of jumps. */
3885 delete_insn (JUMP_LABEL (insn));
3886 /* I feel a little doubtful about this loop,
3887 but I see no clean and sure alternative way
3888 to find the first insn after INSN that is not now deleted.
3889 I hope this works. */
3890 while (next && INSN_DELETED_P (next))
3891 next = NEXT_INSN (next);
3895 /* Likewise if we're deleting a dispatch table. */
3897 if (GET_CODE (insn) == JUMP_INSN
3898 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3899 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3901 rtx pat = PATTERN (insn);
3902 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3903 int len = XVECLEN (pat, diff_vec_p);
3905 for (i = 0; i < len; i++)
3906 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3907 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3908 while (next && INSN_DELETED_P (next))
3909 next = NEXT_INSN (next);
3913 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3914 prev = PREV_INSN (prev);
3916 /* If INSN was a label and a dispatch table follows it,
3917 delete the dispatch table. The tablejump must have gone already.
3918 It isn't useful to fall through into a table. */
3921 && NEXT_INSN (insn) != 0
3922 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3923 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3924 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3925 next = delete_insn (NEXT_INSN (insn));
3927 /* If INSN was a label, delete insns following it if now unreachable. */
3929 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3931 register RTX_CODE code;
3933 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3934 || code == NOTE || code == BARRIER
3935 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3938 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3939 next = NEXT_INSN (next);
3940 /* Keep going past other deleted labels to delete what follows. */
3941 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3942 next = NEXT_INSN (next);
3944 /* Note: if this deletes a jump, it can cause more
3945 deletion of unreachable code, after a different label.
3946 As long as the value from this recursive call is correct,
3947 this invocation functions correctly. */
3948 next = delete_insn (next);
3955 /* Advance from INSN till reaching something not deleted
3956 then return that. May return INSN itself. */
3959 next_nondeleted_insn (insn)
3962 while (INSN_DELETED_P (insn))
3963 insn = NEXT_INSN (insn);
3967 /* Delete a range of insns from FROM to TO, inclusive.
3968 This is for the sake of peephole optimization, so assume
3969 that whatever these insns do will still be done by a new
3970 peephole insn that will replace them. */
3973 delete_for_peephole (from, to)
3974 register rtx from, to;
3976 register rtx insn = from;
3980 register rtx next = NEXT_INSN (insn);
3981 register rtx prev = PREV_INSN (insn);
3983 if (GET_CODE (insn) != NOTE)
3985 INSN_DELETED_P (insn) = 1;
3987 /* Patch this insn out of the chain. */
3988 /* We don't do this all at once, because we
3989 must preserve all NOTEs. */
3991 NEXT_INSN (prev) = next;
3994 PREV_INSN (next) = prev;
4002 /* Note that if TO is an unconditional jump
4003 we *do not* delete the BARRIER that follows,
4004 since the peephole that replaces this sequence
4005 is also an unconditional jump in that case. */
4008 /* Invert the condition of the jump JUMP, and make it jump
4009 to label NLABEL instead of where it jumps now. */
4012 invert_jump (jump, nlabel)
4015 /* We have to either invert the condition and change the label or
4016 do neither. Either operation could fail. We first try to invert
4017 the jump. If that succeeds, we try changing the label. If that fails,
4018 we invert the jump back to what it was. */
4020 if (! invert_exp (PATTERN (jump), jump))
4023 if (redirect_jump (jump, nlabel))
4025 if (flag_branch_probabilities)
4027 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
4029 /* An inverted jump means that a probability taken becomes a
4030 probability not taken. Subtract the branch probability from the
4031 probability base to convert it back to a taken probability.
4032 (We don't flip the probability on a branch that's never taken. */
4033 if (note && XINT (XEXP (note, 0), 0) >= 0)
4034 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
4040 if (! invert_exp (PATTERN (jump), jump))
4041 /* This should just be putting it back the way it was. */
4047 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4049 Return 1 if we can do so, 0 if we cannot find a way to do so that
4050 matches a pattern. */
4053 invert_exp (x, insn)
4057 register RTX_CODE code;
4061 code = GET_CODE (x);
4063 if (code == IF_THEN_ELSE)
4065 register rtx comp = XEXP (x, 0);
4068 /* We can do this in two ways: The preferable way, which can only
4069 be done if this is not an integer comparison, is to reverse
4070 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4071 of the IF_THEN_ELSE. If we can't do either, fail. */
4073 if (can_reverse_comparison_p (comp, insn)
4074 && validate_change (insn, &XEXP (x, 0),
4075 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
4076 GET_MODE (comp), XEXP (comp, 0),
4077 XEXP (comp, 1)), 0))
4081 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
4082 validate_change (insn, &XEXP (x, 2), tem, 1);
4083 return apply_change_group ();
4086 fmt = GET_RTX_FORMAT (code);
4087 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4090 if (! invert_exp (XEXP (x, i), insn))
4095 for (j = 0; j < XVECLEN (x, i); j++)
4096 if (!invert_exp (XVECEXP (x, i, j), insn))
4104 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4105 If the old jump target label is unused as a result,
4106 it and the code following it may be deleted.
4108 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4111 The return value will be 1 if the change was made, 0 if it wasn't (this
4112 can only occur for NLABEL == 0). */
4115 redirect_jump (jump, nlabel)
4118 register rtx olabel = JUMP_LABEL (jump);
4120 if (nlabel == olabel)
4123 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
4126 /* If this is an unconditional branch, delete it from the jump_chain of
4127 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4128 have UID's in range and JUMP_CHAIN is valid). */
4129 if (jump_chain && (simplejump_p (jump)
4130 || GET_CODE (PATTERN (jump)) == RETURN))
4132 int label_index = nlabel ? INSN_UID (nlabel) : 0;
4134 delete_from_jump_chain (jump);
4135 if (label_index < max_jump_chain
4136 && INSN_UID (jump) < max_jump_chain)
4138 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
4139 jump_chain[label_index] = jump;
4143 JUMP_LABEL (jump) = nlabel;
4145 ++LABEL_NUSES (nlabel);
4147 if (olabel && --LABEL_NUSES (olabel) == 0)
4148 delete_insn (olabel);
4153 /* Delete the instruction JUMP from any jump chain it might be on. */
4156 delete_from_jump_chain (jump)
4160 rtx olabel = JUMP_LABEL (jump);
4162 /* Handle unconditional jumps. */
4163 if (jump_chain && olabel != 0
4164 && INSN_UID (olabel) < max_jump_chain
4165 && simplejump_p (jump))
4166 index = INSN_UID (olabel);
4167 /* Handle return insns. */
4168 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
4172 if (jump_chain[index] == jump)
4173 jump_chain[index] = jump_chain[INSN_UID (jump)];
4178 for (insn = jump_chain[index];
4180 insn = jump_chain[INSN_UID (insn)])
4181 if (jump_chain[INSN_UID (insn)] == jump)
4183 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
4189 /* If NLABEL is nonzero, throughout the rtx at LOC,
4190 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4191 zero, alter (RETURN) to (LABEL_REF NLABEL).
4193 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4194 validity with validate_change. Convert (set (pc) (label_ref olabel))
4197 Return 0 if we found a change we would like to make but it is invalid.
4198 Otherwise, return 1. */
4201 redirect_exp (loc, olabel, nlabel, insn)
4206 register rtx x = *loc;
4207 register RTX_CODE code = GET_CODE (x);
4211 if (code == LABEL_REF)
4213 if (XEXP (x, 0) == olabel)
4216 XEXP (x, 0) = nlabel;
4218 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4222 else if (code == RETURN && olabel == 0)
4224 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4225 if (loc == &PATTERN (insn))
4226 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4227 return validate_change (insn, loc, x, 0);
4230 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4231 && GET_CODE (SET_SRC (x)) == LABEL_REF
4232 && XEXP (SET_SRC (x), 0) == olabel)
4233 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4235 fmt = GET_RTX_FORMAT (code);
4236 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4239 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4244 for (j = 0; j < XVECLEN (x, i); j++)
4245 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4253 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4255 If the old jump target label (before the dispatch table) becomes unused,
4256 it and the dispatch table may be deleted. In that case, find the insn
4257 before the jump references that label and delete it and logical successors
4261 redirect_tablejump (jump, nlabel)
4264 register rtx olabel = JUMP_LABEL (jump);
4266 /* Add this jump to the jump_chain of NLABEL. */
4267 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4268 && INSN_UID (jump) < max_jump_chain)
4270 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4271 jump_chain[INSN_UID (nlabel)] = jump;
4274 PATTERN (jump) = gen_jump (nlabel);
4275 JUMP_LABEL (jump) = nlabel;
4276 ++LABEL_NUSES (nlabel);
4277 INSN_CODE (jump) = -1;
4279 if (--LABEL_NUSES (olabel) == 0)
4281 delete_labelref_insn (jump, olabel, 0);
4282 delete_insn (olabel);
4286 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4287 If we found one, delete it and then delete this insn if DELETE_THIS is
4288 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4291 delete_labelref_insn (insn, label, delete_this)
4298 if (GET_CODE (insn) != NOTE
4299 && reg_mentioned_p (label, PATTERN (insn)))
4310 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4311 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4325 /* Like rtx_equal_p except that it considers two REGs as equal
4326 if they renumber to the same value and considers two commutative
4327 operations to be the same if the order of the operands has been
4330 ??? Addition is not commutative on the PA due to the weird implicit
4331 space register selection rules for memory addresses. Therefore, we
4332 don't consider a + b == b + a.
4334 We could/should make this test a little tighter. Possibly only
4335 disabling it on the PA via some backend macro or only disabling this
4336 case when the PLUS is inside a MEM. */
4339 rtx_renumbered_equal_p (x, y)
4343 register RTX_CODE code = GET_CODE (x);
4349 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4350 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4351 && GET_CODE (SUBREG_REG (y)) == REG)))
4353 int reg_x = -1, reg_y = -1;
4354 int word_x = 0, word_y = 0;
4356 if (GET_MODE (x) != GET_MODE (y))
4359 /* If we haven't done any renumbering, don't
4360 make any assumptions. */
4361 if (reg_renumber == 0)
4362 return rtx_equal_p (x, y);
4366 reg_x = REGNO (SUBREG_REG (x));
4367 word_x = SUBREG_WORD (x);
4369 if (reg_renumber[reg_x] >= 0)
4371 reg_x = reg_renumber[reg_x] + word_x;
4379 if (reg_renumber[reg_x] >= 0)
4380 reg_x = reg_renumber[reg_x];
4383 if (GET_CODE (y) == SUBREG)
4385 reg_y = REGNO (SUBREG_REG (y));
4386 word_y = SUBREG_WORD (y);
4388 if (reg_renumber[reg_y] >= 0)
4390 reg_y = reg_renumber[reg_y];
4398 if (reg_renumber[reg_y] >= 0)
4399 reg_y = reg_renumber[reg_y];
4402 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4405 /* Now we have disposed of all the cases
4406 in which different rtx codes can match. */
4407 if (code != GET_CODE (y))
4419 return INTVAL (x) == INTVAL (y);
4422 /* We can't assume nonlocal labels have their following insns yet. */
4423 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4424 return XEXP (x, 0) == XEXP (y, 0);
4426 /* Two label-refs are equivalent if they point at labels
4427 in the same position in the instruction stream. */
4428 return (next_real_insn (XEXP (x, 0))
4429 == next_real_insn (XEXP (y, 0)));
4432 return XSTR (x, 0) == XSTR (y, 0);
4438 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4440 if (GET_MODE (x) != GET_MODE (y))
4443 /* For commutative operations, the RTX match if the operand match in any
4444 order. Also handle the simple binary and unary cases without a loop.
4446 ??? Don't consider PLUS a commutative operator; see comments above. */
4447 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4449 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4450 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4451 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4452 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4453 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4454 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4455 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4456 else if (GET_RTX_CLASS (code) == '1')
4457 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4459 /* Compare the elements. If any pair of corresponding elements
4460 fail to match, return 0 for the whole things. */
4462 fmt = GET_RTX_FORMAT (code);
4463 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4469 if (XWINT (x, i) != XWINT (y, i))
4474 if (XINT (x, i) != XINT (y, i))
4479 if (strcmp (XSTR (x, i), XSTR (y, i)))
4484 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4489 if (XEXP (x, i) != XEXP (y, i))
4496 if (XVECLEN (x, i) != XVECLEN (y, i))
4498 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4499 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4510 /* If X is a hard register or equivalent to one or a subregister of one,
4511 return the hard register number. If X is a pseudo register that was not
4512 assigned a hard register, return the pseudo register number. Otherwise,
4513 return -1. Any rtx is valid for X. */
4519 if (GET_CODE (x) == REG)
4521 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4522 return reg_renumber[REGNO (x)];
4525 if (GET_CODE (x) == SUBREG)
4527 int base = true_regnum (SUBREG_REG (x));
4528 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4529 return SUBREG_WORD (x) + base;
4534 /* Optimize code of the form:
4536 for (x = a[i]; x; ...)
4538 for (x = a[i]; x; ...)
4542 Loop optimize will change the above code into
4546 { ...; if (! (x = ...)) break; }
4549 { ...; if (! (x = ...)) break; }
4552 In general, if the first test fails, the program can branch
4553 directly to `foo' and skip the second try which is doomed to fail.
4554 We run this after loop optimization and before flow analysis. */
4556 /* When comparing the insn patterns, we track the fact that different
4557 pseudo-register numbers may have been used in each computation.
4558 The following array stores an equivalence -- same_regs[I] == J means
4559 that pseudo register I was used in the first set of tests in a context
4560 where J was used in the second set. We also count the number of such
4561 pending equivalences. If nonzero, the expressions really aren't the
4564 static int *same_regs;
4566 static int num_same_regs;
4568 /* Track any registers modified between the target of the first jump and
4569 the second jump. They never compare equal. */
4571 static char *modified_regs;
4573 /* Record if memory was modified. */
4575 static int modified_mem;
4577 /* Called via note_stores on each insn between the target of the first
4578 branch and the second branch. It marks any changed registers. */
4581 mark_modified_reg (dest, x)
4583 rtx x ATTRIBUTE_UNUSED;
4587 if (GET_CODE (dest) == SUBREG)
4588 dest = SUBREG_REG (dest);
4590 if (GET_CODE (dest) == MEM)
4593 if (GET_CODE (dest) != REG)
4596 regno = REGNO (dest);
4597 if (regno >= FIRST_PSEUDO_REGISTER)
4598 modified_regs[regno] = 1;
4600 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4601 modified_regs[regno + i] = 1;
4604 /* F is the first insn in the chain of insns. */
4607 thread_jumps (f, max_reg, flag_before_loop)
4610 int flag_before_loop;
4612 /* Basic algorithm is to find a conditional branch,
4613 the label it may branch to, and the branch after
4614 that label. If the two branches test the same condition,
4615 walk back from both branch paths until the insn patterns
4616 differ, or code labels are hit. If we make it back to
4617 the target of the first branch, then we know that the first branch
4618 will either always succeed or always fail depending on the relative
4619 senses of the two branches. So adjust the first branch accordingly
4622 rtx label, b1, b2, t1, t2;
4623 enum rtx_code code1, code2;
4624 rtx b1op0, b1op1, b2op0, b2op1;
4629 /* Allocate register tables and quick-reset table. */
4630 modified_regs = (char *) alloca (max_reg * sizeof (char));
4631 same_regs = (int *) alloca (max_reg * sizeof (int));
4632 all_reset = (int *) alloca (max_reg * sizeof (int));
4633 for (i = 0; i < max_reg; i++)
4640 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4642 /* Get to a candidate branch insn. */
4643 if (GET_CODE (b1) != JUMP_INSN
4644 || ! condjump_p (b1) || simplejump_p (b1)
4645 || JUMP_LABEL (b1) == 0)
4648 bzero (modified_regs, max_reg * sizeof (char));
4651 bcopy ((char *) all_reset, (char *) same_regs,
4652 max_reg * sizeof (int));
4655 label = JUMP_LABEL (b1);
4657 /* Look for a branch after the target. Record any registers and
4658 memory modified between the target and the branch. Stop when we
4659 get to a label since we can't know what was changed there. */
4660 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4662 if (GET_CODE (b2) == CODE_LABEL)
4665 else if (GET_CODE (b2) == JUMP_INSN)
4667 /* If this is an unconditional jump and is the only use of
4668 its target label, we can follow it. */
4669 if (simplejump_p (b2)
4670 && JUMP_LABEL (b2) != 0
4671 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4673 b2 = JUMP_LABEL (b2);
4680 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4683 if (GET_CODE (b2) == CALL_INSN)
4686 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4687 if (call_used_regs[i] && ! fixed_regs[i]
4688 && i != STACK_POINTER_REGNUM
4689 && i != FRAME_POINTER_REGNUM
4690 && i != HARD_FRAME_POINTER_REGNUM
4691 && i != ARG_POINTER_REGNUM)
4692 modified_regs[i] = 1;
4695 note_stores (PATTERN (b2), mark_modified_reg);
4698 /* Check the next candidate branch insn from the label
4701 || GET_CODE (b2) != JUMP_INSN
4703 || ! condjump_p (b2)
4704 || simplejump_p (b2))
4707 /* Get the comparison codes and operands, reversing the
4708 codes if appropriate. If we don't have comparison codes,
4709 we can't do anything. */
4710 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4711 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4712 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4713 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4714 code1 = reverse_condition (code1);
4716 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4717 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4718 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4719 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4720 code2 = reverse_condition (code2);
4722 /* If they test the same things and knowing that B1 branches
4723 tells us whether or not B2 branches, check if we
4724 can thread the branch. */
4725 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4726 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4727 && (comparison_dominates_p (code1, code2)
4728 || (comparison_dominates_p (code1, reverse_condition (code2))
4729 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
4733 t1 = prev_nonnote_insn (b1);
4734 t2 = prev_nonnote_insn (b2);
4736 while (t1 != 0 && t2 != 0)
4740 /* We have reached the target of the first branch.
4741 If there are no pending register equivalents,
4742 we know that this branch will either always
4743 succeed (if the senses of the two branches are
4744 the same) or always fail (if not). */
4747 if (num_same_regs != 0)
4750 if (comparison_dominates_p (code1, code2))
4751 new_label = JUMP_LABEL (b2);
4753 new_label = get_label_after (b2);
4755 if (JUMP_LABEL (b1) != new_label)
4757 rtx prev = PREV_INSN (new_label);
4759 if (flag_before_loop
4760 && GET_CODE (prev) == NOTE
4761 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4763 /* Don't thread to the loop label. If a loop
4764 label is reused, loop optimization will
4765 be disabled for that loop. */
4766 new_label = gen_label_rtx ();
4767 emit_label_after (new_label, PREV_INSN (prev));
4769 changed |= redirect_jump (b1, new_label);
4774 /* If either of these is not a normal insn (it might be
4775 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4776 have already been skipped above.) Similarly, fail
4777 if the insns are different. */
4778 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4779 || recog_memoized (t1) != recog_memoized (t2)
4780 || ! rtx_equal_for_thread_p (PATTERN (t1),
4784 t1 = prev_nonnote_insn (t1);
4785 t2 = prev_nonnote_insn (t2);
4792 /* This is like RTX_EQUAL_P except that it knows about our handling of
4793 possibly equivalent registers and knows to consider volatile and
4794 modified objects as not equal.
4796 YINSN is the insn containing Y. */
4799 rtx_equal_for_thread_p (x, y, yinsn)
4805 register enum rtx_code code;
4808 code = GET_CODE (x);
4809 /* Rtx's of different codes cannot be equal. */
4810 if (code != GET_CODE (y))
4813 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4814 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4816 if (GET_MODE (x) != GET_MODE (y))
4819 /* For floating-point, consider everything unequal. This is a bit
4820 pessimistic, but this pass would only rarely do anything for FP
4822 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4823 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
4826 /* For commutative operations, the RTX match if the operand match in any
4827 order. Also handle the simple binary and unary cases without a loop. */
4828 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4829 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4830 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4831 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4832 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4833 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4834 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4835 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4836 else if (GET_RTX_CLASS (code) == '1')
4837 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4839 /* Handle special-cases first. */
4843 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4846 /* If neither is user variable or hard register, check for possible
4848 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4849 || REGNO (x) < FIRST_PSEUDO_REGISTER
4850 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4853 if (same_regs[REGNO (x)] == -1)
4855 same_regs[REGNO (x)] = REGNO (y);
4858 /* If this is the first time we are seeing a register on the `Y'
4859 side, see if it is the last use. If not, we can't thread the
4860 jump, so mark it as not equivalent. */
4861 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4867 return (same_regs[REGNO (x)] == REGNO (y));
4872 /* If memory modified or either volatile, not equivalent.
4873 Else, check address. */
4874 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4877 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4880 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4886 /* Cancel a pending `same_regs' if setting equivalenced registers.
4887 Then process source. */
4888 if (GET_CODE (SET_DEST (x)) == REG
4889 && GET_CODE (SET_DEST (y)) == REG)
4891 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4893 same_regs[REGNO (SET_DEST (x))] = -1;
4896 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4900 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4903 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4906 return XEXP (x, 0) == XEXP (y, 0);
4909 return XSTR (x, 0) == XSTR (y, 0);
4918 fmt = GET_RTX_FORMAT (code);
4919 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4924 if (XWINT (x, i) != XWINT (y, i))
4930 if (XINT (x, i) != XINT (y, i))
4936 /* Two vectors must have the same length. */
4937 if (XVECLEN (x, i) != XVECLEN (y, i))
4940 /* And the corresponding elements must match. */
4941 for (j = 0; j < XVECLEN (x, i); j++)
4942 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4943 XVECEXP (y, i, j), yinsn) == 0)
4948 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4954 if (strcmp (XSTR (x, i), XSTR (y, i)))
4959 /* These are just backpointers, so they don't matter. */
4965 /* It is believed that rtx's at this level will never
4966 contain anything but integers and other rtx's,
4967 except for within LABEL_REFs and SYMBOL_REFs. */
4977 /* Return the insn that NEW can be safely inserted in front of starting at
4978 the jump insn INSN. Return 0 if it is not safe to do this jump
4979 optimization. Note that NEW must contain a single set. */
4982 find_insert_position (insn, new)
4989 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
4990 if (GET_CODE (PATTERN (new)) != PARALLEL)
4993 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
4994 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
4995 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5002 /* There is a good chance that the previous insn PREV sets the thing
5003 being clobbered (often the CC in a hard reg). If PREV does not
5004 use what NEW sets, we can insert NEW before PREV. */
5006 prev = prev_active_insn (insn);
5007 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5008 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5009 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5011 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5015 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
5017 #endif /* !HAVE_cc0 */