1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-98, 1999 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"
62 #include "insn-attr.h"
69 /* ??? Eventually must record somehow the labels used by jumps
70 from nested functions. */
71 /* Pre-record the next or previous real insn for each label?
72 No, this pass is very fast anyway. */
73 /* Condense consecutive labels?
74 This would make life analysis faster, maybe. */
75 /* Optimize jump y; x: ... y: jumpif... x?
76 Don't know if it is worth bothering with. */
77 /* Optimize two cases of conditional jump to conditional jump?
78 This can never delete any instruction or make anything dead,
79 or even change what is live at any point.
80 So perhaps let combiner do it. */
82 /* Vector indexed by uid.
83 For each CODE_LABEL, index by its uid to get first unconditional jump
84 that jumps to the label.
85 For each JUMP_INSN, index by its uid to get the next unconditional jump
86 that jumps to the same label.
87 Element 0 is the start of a chain of all return insns.
88 (It is safe to use element 0 because insn uid 0 is not used. */
90 static rtx *jump_chain;
92 /* List of labels referred to from initializers.
93 These can never be deleted. */
96 /* Maximum index in jump_chain. */
98 static int max_jump_chain;
100 /* Set nonzero by jump_optimize if control can fall through
101 to the end of the function. */
104 /* Indicates whether death notes are significant in cross jump analysis.
105 Normally they are not significant, because of A and B jump to C,
106 and R dies in A, it must die in B. But this might not be true after
107 stack register conversion, and we must compare death notes in that
110 static int cross_jump_death_matters = 0;
112 static int init_label_info PROTO((rtx));
113 static void delete_barrier_successors PROTO((rtx));
114 static void mark_all_labels PROTO((rtx, int));
115 static rtx delete_unreferenced_labels PROTO((rtx));
116 static void delete_noop_moves PROTO((rtx));
117 static int calculate_can_reach_end PROTO((rtx, int, int));
118 static int duplicate_loop_exit_test PROTO((rtx));
119 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
120 static void do_cross_jump PROTO((rtx, rtx, rtx));
121 static int jump_back_p PROTO((rtx, rtx));
122 static int tension_vector_labels PROTO((rtx, int));
123 static void mark_jump_label PROTO((rtx, rtx, int));
124 static void delete_computation PROTO((rtx));
125 static void delete_from_jump_chain PROTO((rtx));
126 static int delete_labelref_insn PROTO((rtx, rtx, int));
127 static void mark_modified_reg PROTO((rtx, rtx));
128 static void redirect_tablejump PROTO((rtx, rtx));
129 static void jump_optimize_1 PROTO ((rtx, int, int, int, int));
131 static rtx find_insert_position PROTO((rtx, rtx));
134 /* Main external entry point into the jump optimizer. See comments before
135 jump_optimize_1 for descriptions of the arguments. */
137 jump_optimize (f, cross_jump, noop_moves, after_regscan)
143 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0);
146 /* Alternate entry into the jump optimizer. This entry point only rebuilds
147 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
150 rebuild_jump_labels (f)
153 jump_optimize_1 (f, 0, 0, 0, 1);
157 /* Delete no-op jumps and optimize jumps to jumps
158 and jumps around jumps.
159 Delete unused labels and unreachable code.
161 If CROSS_JUMP is 1, detect matching code
162 before a jump and its destination and unify them.
163 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
165 If NOOP_MOVES is nonzero, delete no-op move insns.
167 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
168 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
170 If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
171 and JUMP_LABEL field for jumping insns.
173 If `optimize' is zero, don't change any code,
174 just determine whether control drops off the end of the function.
175 This case occurs when we have -W and not -O.
176 It works because `delete_insn' checks the value of `optimize'
177 and refrains from actually deleting when that is 0. */
180 jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, mark_labels_only)
185 int mark_labels_only;
187 register rtx insn, next;
194 cross_jump_death_matters = (cross_jump == 2);
195 max_uid = init_label_info (f) + 1;
197 /* If we are performing cross jump optimizations, then initialize
198 tables mapping UIDs to EH regions to avoid incorrect movement
199 of insns from one EH region to another. */
200 if (flag_exceptions && cross_jump)
201 init_insn_eh_region (f, max_uid);
203 delete_barrier_successors (f);
205 /* Leave some extra room for labels and duplicate exit test insns
207 max_jump_chain = max_uid * 14 / 10;
208 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
209 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
211 mark_all_labels (f, cross_jump);
213 /* Keep track of labels used from static data;
214 they cannot ever be deleted. */
216 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
217 LABEL_NUSES (XEXP (insn, 0))++;
219 check_exception_handler_labels ();
221 /* Keep track of labels used for marking handlers for exception
222 regions; they cannot usually be deleted. */
224 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
225 LABEL_NUSES (XEXP (insn, 0))++;
227 /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
228 notes and recompute LABEL_NUSES. */
229 if (mark_labels_only)
232 exception_optimize ();
234 last_insn = delete_unreferenced_labels (f);
238 /* CAN_REACH_END is persistent for each function. Once set it should
239 not be cleared. This is especially true for the case where we
240 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
241 the front-end before compiling each function. */
242 if (calculate_can_reach_end (last_insn, 1, 0))
245 /* Zero the "deleted" flag of all the "deleted" insns. */
246 for (insn = f; insn; insn = NEXT_INSN (insn))
247 INSN_DELETED_P (insn) = 0;
249 /* Show that the jump chain is not valid. */
257 /* If we fall through to the epilogue, see if we can insert a RETURN insn
258 in front of it. If the machine allows it at this point (we might be
259 after reload for a leaf routine), it will improve optimization for it
261 insn = get_last_insn ();
262 while (insn && GET_CODE (insn) == NOTE)
263 insn = PREV_INSN (insn);
265 if (insn && GET_CODE (insn) != BARRIER)
267 emit_jump_insn (gen_return ());
274 delete_noop_moves (f);
276 /* If we haven't yet gotten to reload and we have just run regscan,
277 delete any insn that sets a register that isn't used elsewhere.
278 This helps some of the optimizations below by having less insns
279 being jumped around. */
281 if (! reload_completed && after_regscan)
282 for (insn = f; insn; insn = next)
284 rtx set = single_set (insn);
286 next = NEXT_INSN (insn);
288 if (set && GET_CODE (SET_DEST (set)) == REG
289 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
290 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
291 /* We use regno_last_note_uid so as not to delete the setting
292 of a reg that's used in notes. A subsequent optimization
293 might arrange to use that reg for real. */
294 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
295 && ! side_effects_p (SET_SRC (set))
296 && ! find_reg_note (insn, REG_RETVAL, 0))
300 /* Now iterate optimizing jumps until nothing changes over one pass. */
302 old_max_reg = max_reg_num ();
307 for (insn = f; insn; insn = next)
310 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
312 int this_is_simplejump, this_is_condjump, reversep = 0;
313 int this_is_condjump_in_parallel;
316 /* If NOT the first iteration, if this is the last jump pass
317 (just before final), do the special peephole optimizations.
318 Avoiding the first iteration gives ordinary jump opts
319 a chance to work before peephole opts. */
321 if (reload_completed && !first && !flag_no_peephole)
322 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
326 /* That could have deleted some insns after INSN, so check now
327 what the following insn is. */
329 next = NEXT_INSN (insn);
331 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
332 jump. Try to optimize by duplicating the loop exit test if so.
333 This is only safe immediately after regscan, because it uses
334 the values of regno_first_uid and regno_last_uid. */
335 if (after_regscan && GET_CODE (insn) == NOTE
336 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
337 && (temp1 = next_nonnote_insn (insn)) != 0
338 && simplejump_p (temp1))
340 temp = PREV_INSN (insn);
341 if (duplicate_loop_exit_test (insn))
344 next = NEXT_INSN (temp);
349 if (GET_CODE (insn) != JUMP_INSN)
352 this_is_simplejump = simplejump_p (insn);
353 this_is_condjump = condjump_p (insn);
354 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
356 /* Tension the labels in dispatch tables. */
358 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
359 changed |= tension_vector_labels (PATTERN (insn), 0);
360 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
361 changed |= tension_vector_labels (PATTERN (insn), 1);
363 /* If a dispatch table always goes to the same place,
364 get rid of it and replace the insn that uses it. */
366 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
367 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
370 rtx pat = PATTERN (insn);
371 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
372 int len = XVECLEN (pat, diff_vec_p);
373 rtx dispatch = prev_real_insn (insn);
375 for (i = 0; i < len; i++)
376 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
377 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
381 && GET_CODE (dispatch) == JUMP_INSN
382 && JUMP_LABEL (dispatch) != 0
383 /* Don't mess with a casesi insn. */
384 && !(GET_CODE (PATTERN (dispatch)) == SET
385 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
387 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
389 redirect_tablejump (dispatch,
390 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
395 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
397 /* If a jump references the end of the function, try to turn
398 it into a RETURN insn, possibly a conditional one. */
399 if (JUMP_LABEL (insn)
400 && (next_active_insn (JUMP_LABEL (insn)) == 0
401 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
403 changed |= redirect_jump (insn, NULL_RTX);
405 /* Detect jump to following insn. */
406 if (reallabelprev == insn && condjump_p (insn))
408 next = next_real_insn (JUMP_LABEL (insn));
414 /* If we have an unconditional jump preceded by a USE, try to put
415 the USE before the target and jump there. This simplifies many
416 of the optimizations below since we don't have to worry about
417 dealing with these USE insns. We only do this if the label
418 being branch to already has the identical USE or if code
419 never falls through to that label. */
421 if (this_is_simplejump
422 && (temp = prev_nonnote_insn (insn)) != 0
423 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
424 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
425 && (GET_CODE (temp1) == BARRIER
426 || (GET_CODE (temp1) == INSN
427 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
428 /* Don't do this optimization if we have a loop containing only
429 the USE instruction, and the loop start label has a usage
430 count of 1. This is because we will redo this optimization
431 everytime through the outer loop, and jump opt will never
433 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
434 && temp2 == JUMP_LABEL (insn)
435 && LABEL_NUSES (temp2) == 1))
437 if (GET_CODE (temp1) == BARRIER)
439 emit_insn_after (PATTERN (temp), temp1);
440 temp1 = NEXT_INSN (temp1);
444 redirect_jump (insn, get_label_before (temp1));
445 reallabelprev = prev_real_insn (temp1);
449 /* Simplify if (...) x = a; else x = b; by converting it
450 to x = b; if (...) x = a;
451 if B is sufficiently simple, the test doesn't involve X,
452 and nothing in the test modifies B or X.
454 If we have small register classes, we also can't do this if X
457 If the "x = b;" insn has any REG_NOTES, we don't do this because
458 of the possibility that we are running after CSE and there is a
459 REG_EQUAL note that is only valid if the branch has already been
460 taken. If we move the insn with the REG_EQUAL note, we may
461 fold the comparison to always be false in a later CSE pass.
462 (We could also delete the REG_NOTES when moving the insn, but it
463 seems simpler to not move it.) An exception is that we can move
464 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
465 value is the same as "b".
467 INSN is the branch over the `else' part.
471 TEMP to the jump insn preceding "x = a;"
473 TEMP2 to the insn that sets "x = b;"
474 TEMP3 to the insn that sets "x = a;"
475 TEMP4 to the set of "x = b"; */
477 if (this_is_simplejump
478 && (temp3 = prev_active_insn (insn)) != 0
479 && GET_CODE (temp3) == INSN
480 && (temp4 = single_set (temp3)) != 0
481 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
482 && (! SMALL_REGISTER_CLASSES
483 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
484 && (temp2 = next_active_insn (insn)) != 0
485 && GET_CODE (temp2) == INSN
486 && (temp4 = single_set (temp2)) != 0
487 && rtx_equal_p (SET_DEST (temp4), temp1)
488 && ! side_effects_p (SET_SRC (temp4))
489 && ! may_trap_p (SET_SRC (temp4))
490 && (REG_NOTES (temp2) == 0
491 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
492 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
493 && XEXP (REG_NOTES (temp2), 1) == 0
494 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
496 && (temp = prev_active_insn (temp3)) != 0
497 && condjump_p (temp) && ! simplejump_p (temp)
498 /* TEMP must skip over the "x = a;" insn */
499 && prev_real_insn (JUMP_LABEL (temp)) == insn
500 && no_labels_between_p (insn, JUMP_LABEL (temp))
501 /* There must be no other entries to the "x = b;" insn. */
502 && no_labels_between_p (JUMP_LABEL (temp), temp2)
503 /* INSN must either branch to the insn after TEMP2 or the insn
504 after TEMP2 must branch to the same place as INSN. */
505 && (reallabelprev == temp2
506 || ((temp5 = next_active_insn (temp2)) != 0
507 && simplejump_p (temp5)
508 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
510 /* The test expression, X, may be a complicated test with
511 multiple branches. See if we can find all the uses of
512 the label that TEMP branches to without hitting a CALL_INSN
513 or a jump to somewhere else. */
514 rtx target = JUMP_LABEL (temp);
515 int nuses = LABEL_NUSES (target);
521 /* Set P to the first jump insn that goes around "x = a;". */
522 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
524 if (GET_CODE (p) == JUMP_INSN)
526 if (condjump_p (p) && ! simplejump_p (p)
527 && JUMP_LABEL (p) == target)
536 else if (GET_CODE (p) == CALL_INSN)
541 /* We cannot insert anything between a set of cc and its use
542 so if P uses cc0, we must back up to the previous insn. */
543 q = prev_nonnote_insn (p);
544 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
545 && sets_cc0_p (PATTERN (q)))
552 /* If we found all the uses and there was no data conflict, we
553 can move the assignment unless we can branch into the middle
556 && no_labels_between_p (p, insn)
557 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
558 && ! reg_set_between_p (temp1, p, temp3)
559 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
560 || ! modified_between_p (SET_SRC (temp4), p, temp2))
561 /* Verify that registers used by the jump are not clobbered
562 by the instruction being moved. */
563 && ! regs_set_between_p (PATTERN (temp),
567 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
570 /* Set NEXT to an insn that we know won't go away. */
571 next = next_active_insn (insn);
573 /* Delete the jump around the set. Note that we must do
574 this before we redirect the test jumps so that it won't
575 delete the code immediately following the assignment
576 we moved (which might be a jump). */
580 /* We either have two consecutive labels or a jump to
581 a jump, so adjust all the JUMP_INSNs to branch to where
583 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
584 if (GET_CODE (p) == JUMP_INSN)
585 redirect_jump (p, target);
592 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
593 to x = a; if (...) goto l; x = b;
594 if A is sufficiently simple, the test doesn't involve X,
595 and nothing in the test modifies A or X.
597 If we have small register classes, we also can't do this if X
600 If the "x = a;" insn has any REG_NOTES, we don't do this because
601 of the possibility that we are running after CSE and there is a
602 REG_EQUAL note that is only valid if the branch has already been
603 taken. If we move the insn with the REG_EQUAL note, we may
604 fold the comparison to always be false in a later CSE pass.
605 (We could also delete the REG_NOTES when moving the insn, but it
606 seems simpler to not move it.) An exception is that we can move
607 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
608 value is the same as "a".
614 TEMP to the jump insn preceding "x = a;"
616 TEMP2 to the insn that sets "x = b;"
617 TEMP3 to the insn that sets "x = a;"
618 TEMP4 to the set of "x = a"; */
620 if (this_is_simplejump
621 && (temp2 = next_active_insn (insn)) != 0
622 && GET_CODE (temp2) == INSN
623 && (temp4 = single_set (temp2)) != 0
624 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
625 && (! SMALL_REGISTER_CLASSES
626 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
627 && (temp3 = prev_active_insn (insn)) != 0
628 && GET_CODE (temp3) == INSN
629 && (temp4 = single_set (temp3)) != 0
630 && rtx_equal_p (SET_DEST (temp4), temp1)
631 && ! side_effects_p (SET_SRC (temp4))
632 && ! may_trap_p (SET_SRC (temp4))
633 && (REG_NOTES (temp3) == 0
634 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
635 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
636 && XEXP (REG_NOTES (temp3), 1) == 0
637 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
639 && (temp = prev_active_insn (temp3)) != 0
640 && condjump_p (temp) && ! simplejump_p (temp)
641 /* TEMP must skip over the "x = a;" insn */
642 && prev_real_insn (JUMP_LABEL (temp)) == insn
643 && no_labels_between_p (temp, insn))
645 rtx prev_label = JUMP_LABEL (temp);
646 rtx insert_after = prev_nonnote_insn (temp);
649 /* We cannot insert anything between a set of cc and its use. */
650 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
651 && sets_cc0_p (PATTERN (insert_after)))
652 insert_after = prev_nonnote_insn (insert_after);
654 ++LABEL_NUSES (prev_label);
657 && no_labels_between_p (insert_after, temp)
658 && ! reg_referenced_between_p (temp1, insert_after, temp3)
659 && ! reg_referenced_between_p (temp1, temp3,
661 && ! reg_set_between_p (temp1, insert_after, temp)
662 && ! modified_between_p (SET_SRC (temp4), insert_after, temp)
663 /* Verify that registers used by the jump are not clobbered
664 by the instruction being moved. */
665 && ! regs_set_between_p (PATTERN (temp),
668 && invert_jump (temp, JUMP_LABEL (insn)))
670 emit_insn_after_with_line_notes (PATTERN (temp3),
671 insert_after, temp3);
674 /* Set NEXT to an insn that we know won't go away. */
678 if (prev_label && --LABEL_NUSES (prev_label) == 0)
679 delete_insn (prev_label);
685 /* If we have if (...) x = exp; and branches are expensive,
686 EXP is a single insn, does not have any side effects, cannot
687 trap, and is not too costly, convert this to
688 t = exp; if (...) x = t;
690 Don't do this when we have CC0 because it is unlikely to help
691 and we'd need to worry about where to place the new insn and
692 the potential for conflicts. We also can't do this when we have
693 notes on the insn for the same reason as above.
697 TEMP to the "x = exp;" insn.
698 TEMP1 to the single set in the "x = exp;" insn.
701 if (! reload_completed
702 && this_is_condjump && ! this_is_simplejump
704 && (temp = next_nonnote_insn (insn)) != 0
705 && GET_CODE (temp) == INSN
706 && REG_NOTES (temp) == 0
707 && (reallabelprev == temp
708 || ((temp2 = next_active_insn (temp)) != 0
709 && simplejump_p (temp2)
710 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
711 && (temp1 = single_set (temp)) != 0
712 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
713 && (! SMALL_REGISTER_CLASSES
714 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
715 && GET_CODE (SET_SRC (temp1)) != REG
716 && GET_CODE (SET_SRC (temp1)) != SUBREG
717 && GET_CODE (SET_SRC (temp1)) != CONST_INT
718 && ! side_effects_p (SET_SRC (temp1))
719 && ! may_trap_p (SET_SRC (temp1))
720 && rtx_cost (SET_SRC (temp1), SET) < 10)
722 rtx new = gen_reg_rtx (GET_MODE (temp2));
724 if ((temp3 = find_insert_position (insn, temp))
725 && validate_change (temp, &SET_DEST (temp1), new, 0))
727 next = emit_insn_after (gen_move_insn (temp2, new), insn);
728 emit_insn_after_with_line_notes (PATTERN (temp),
729 PREV_INSN (temp3), temp);
731 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
735 reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
736 old_max_reg = max_reg_num ();
741 /* Similarly, if it takes two insns to compute EXP but they
742 have the same destination. Here TEMP3 will be the second
743 insn and TEMP4 the SET from that insn. */
745 if (! reload_completed
746 && this_is_condjump && ! this_is_simplejump
748 && (temp = next_nonnote_insn (insn)) != 0
749 && GET_CODE (temp) == INSN
750 && REG_NOTES (temp) == 0
751 && (temp3 = next_nonnote_insn (temp)) != 0
752 && GET_CODE (temp3) == INSN
753 && REG_NOTES (temp3) == 0
754 && (reallabelprev == temp3
755 || ((temp2 = next_active_insn (temp3)) != 0
756 && simplejump_p (temp2)
757 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
758 && (temp1 = single_set (temp)) != 0
759 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
760 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
761 && (! SMALL_REGISTER_CLASSES
762 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
763 && ! side_effects_p (SET_SRC (temp1))
764 && ! may_trap_p (SET_SRC (temp1))
765 && rtx_cost (SET_SRC (temp1), SET) < 10
766 && (temp4 = single_set (temp3)) != 0
767 && rtx_equal_p (SET_DEST (temp4), temp2)
768 && ! side_effects_p (SET_SRC (temp4))
769 && ! may_trap_p (SET_SRC (temp4))
770 && rtx_cost (SET_SRC (temp4), SET) < 10)
772 rtx new = gen_reg_rtx (GET_MODE (temp2));
774 if ((temp5 = find_insert_position (insn, temp))
775 && (temp6 = find_insert_position (insn, temp3))
776 && validate_change (temp, &SET_DEST (temp1), new, 0))
778 /* Use the earliest of temp5 and temp6. */
781 next = emit_insn_after (gen_move_insn (temp2, new), insn);
782 emit_insn_after_with_line_notes (PATTERN (temp),
783 PREV_INSN (temp6), temp);
784 emit_insn_after_with_line_notes
785 (replace_rtx (PATTERN (temp3), temp2, new),
786 PREV_INSN (temp6), temp3);
789 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
793 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
794 old_max_reg = max_reg_num ();
799 /* Finally, handle the case where two insns are used to
800 compute EXP but a temporary register is used. Here we must
801 ensure that the temporary register is not used anywhere else. */
803 if (! reload_completed
805 && this_is_condjump && ! this_is_simplejump
807 && (temp = next_nonnote_insn (insn)) != 0
808 && GET_CODE (temp) == INSN
809 && REG_NOTES (temp) == 0
810 && (temp3 = next_nonnote_insn (temp)) != 0
811 && GET_CODE (temp3) == INSN
812 && REG_NOTES (temp3) == 0
813 && (reallabelprev == temp3
814 || ((temp2 = next_active_insn (temp3)) != 0
815 && simplejump_p (temp2)
816 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
817 && (temp1 = single_set (temp)) != 0
818 && (temp5 = SET_DEST (temp1),
819 (GET_CODE (temp5) == REG
820 || (GET_CODE (temp5) == SUBREG
821 && (temp5 = SUBREG_REG (temp5),
822 GET_CODE (temp5) == REG))))
823 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
824 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
825 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
826 && ! side_effects_p (SET_SRC (temp1))
827 && ! may_trap_p (SET_SRC (temp1))
828 && rtx_cost (SET_SRC (temp1), SET) < 10
829 && (temp4 = single_set (temp3)) != 0
830 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
831 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
832 && (! SMALL_REGISTER_CLASSES
833 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
834 && rtx_equal_p (SET_DEST (temp4), temp2)
835 && ! side_effects_p (SET_SRC (temp4))
836 && ! may_trap_p (SET_SRC (temp4))
837 && rtx_cost (SET_SRC (temp4), SET) < 10)
839 rtx new = gen_reg_rtx (GET_MODE (temp2));
841 if ((temp5 = find_insert_position (insn, temp))
842 && (temp6 = find_insert_position (insn, temp3))
843 && validate_change (temp3, &SET_DEST (temp4), new, 0))
845 /* Use the earliest of temp5 and temp6. */
848 next = emit_insn_after (gen_move_insn (temp2, new), insn);
849 emit_insn_after_with_line_notes (PATTERN (temp),
850 PREV_INSN (temp6), temp);
851 emit_insn_after_with_line_notes (PATTERN (temp3),
852 PREV_INSN (temp6), temp3);
855 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
859 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
860 old_max_reg = max_reg_num ();
864 #endif /* HAVE_cc0 */
866 /* Try to use a conditional move (if the target has them), or a
867 store-flag insn. The general case is:
869 1) x = a; if (...) x = b; and
872 If the jump would be faster, the machine should not have defined
873 the movcc or scc insns!. These cases are often made by the
874 previous optimization.
876 The second case is treated as x = x; if (...) x = b;.
878 INSN here is the jump around the store. We set:
880 TEMP to the "x = b;" insn.
883 TEMP3 to A (X in the second case).
884 TEMP4 to the condition being tested.
885 TEMP5 to the earliest insn used to find the condition. */
887 if (/* We can't do this after reload has completed. */
889 && this_is_condjump && ! this_is_simplejump
890 /* Set TEMP to the "x = b;" insn. */
891 && (temp = next_nonnote_insn (insn)) != 0
892 && GET_CODE (temp) == INSN
893 && GET_CODE (PATTERN (temp)) == SET
894 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
895 && (! SMALL_REGISTER_CLASSES
896 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
897 && ! side_effects_p (temp2 = SET_SRC (PATTERN (temp)))
898 && ! may_trap_p (temp2)
899 /* Allow either form, but prefer the former if both apply.
900 There is no point in using the old value of TEMP1 if
901 it is a register, since cse will alias them. It can
902 lose if the old value were a hard register since CSE
903 won't replace hard registers. Avoid using TEMP3 if
904 small register classes and it is a hard register. */
905 && (((temp3 = reg_set_last (temp1, insn)) != 0
906 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
907 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
908 /* Make the latter case look like x = x; if (...) x = b; */
909 || (temp3 = temp1, 1))
910 /* INSN must either branch to the insn after TEMP or the insn
911 after TEMP must branch to the same place as INSN. */
912 && (reallabelprev == temp
913 || ((temp4 = next_active_insn (temp)) != 0
914 && simplejump_p (temp4)
915 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
916 && (temp4 = get_condition (insn, &temp5)) != 0
917 /* We must be comparing objects whose modes imply the size.
918 We could handle BLKmode if (1) emit_store_flag could
919 and (2) we could find the size reliably. */
920 && GET_MODE (XEXP (temp4, 0)) != BLKmode
921 /* Even if branches are cheap, the store_flag optimization
922 can win when the operation to be performed can be
923 expressed directly. */
925 /* If the previous insn sets CC0 and something else, we can't
926 do this since we are going to delete that insn. */
928 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
929 && GET_CODE (temp6) == INSN
930 && (sets_cc0_p (PATTERN (temp6)) == -1
931 || (sets_cc0_p (PATTERN (temp6)) == 1
932 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
936 #ifdef HAVE_conditional_move
937 /* First try a conditional move. */
939 enum rtx_code code = GET_CODE (temp4);
941 rtx cond0, cond1, aval, bval;
944 /* Copy the compared variables into cond0 and cond1, so that
945 any side effects performed in or after the old comparison,
946 will not affect our compare which will come later. */
947 /* ??? Is it possible to just use the comparison in the jump
948 insn? After all, we're going to delete it. We'd have
949 to modify emit_conditional_move to take a comparison rtx
950 instead or write a new function. */
951 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
952 /* We want the target to be able to simplify comparisons with
953 zero (and maybe other constants as well), so don't create
954 pseudos for them. There's no need to either. */
955 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
956 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
957 cond1 = XEXP (temp4, 1);
959 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
965 target = emit_conditional_move (var, code,
966 cond0, cond1, VOIDmode,
967 aval, bval, GET_MODE (var),
968 (code == LTU || code == GEU
969 || code == LEU || code == GTU));
973 rtx seq1, seq2, last;
976 /* Save the conditional move sequence but don't emit it
977 yet. On some machines, like the alpha, it is possible
978 that temp5 == insn, so next generate the sequence that
979 saves the compared values and then emit both
980 sequences ensuring seq1 occurs before seq2. */
984 /* "Now that we can't fail..." Famous last words.
985 Generate the copy insns that preserve the compared
988 emit_move_insn (cond0, XEXP (temp4, 0));
989 if (cond1 != XEXP (temp4, 1))
990 emit_move_insn (cond1, XEXP (temp4, 1));
994 /* Validate the sequence -- this may be some weird
995 bit-extract-and-test instruction for which there
996 exists no complimentary bit-extract insn. */
998 for (last = seq1; last ; last = NEXT_INSN (last))
999 if (recog_memoized (last) < 0)
1007 emit_insns_before (seq1, temp5);
1009 /* Insert conditional move after insn, to be sure
1010 that the jump and a possible compare won't be
1012 last = emit_insns_after (seq2, insn);
1014 /* ??? We can also delete the insn that sets X to A.
1015 Flow will do it too though. */
1017 next = NEXT_INSN (insn);
1022 reg_scan_update (seq1, NEXT_INSN (last),
1024 old_max_reg = max_reg_num ();
1036 /* That didn't work, try a store-flag insn.
1038 We further divide the cases into:
1040 1) x = a; if (...) x = b; and either A or B is zero,
1041 2) if (...) x = 0; and jumps are expensive,
1042 3) x = a; if (...) x = b; and A and B are constants where all
1043 the set bits in A are also set in B and jumps are expensive,
1044 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1046 5) if (...) x = b; if jumps are even more expensive. */
1048 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1049 && ((GET_CODE (temp3) == CONST_INT)
1050 /* Make the latter case look like
1051 x = x; if (...) x = 0; */
1054 && temp2 == const0_rtx)
1055 || BRANCH_COST >= 3)))
1056 /* If B is zero, OK; if A is zero, can only do (1) if we
1057 can reverse the condition. See if (3) applies possibly
1058 by reversing the condition. Prefer reversing to (4) when
1059 branches are very expensive. */
1060 && (((BRANCH_COST >= 2
1061 || STORE_FLAG_VALUE == -1
1062 || (STORE_FLAG_VALUE == 1
1063 /* Check that the mask is a power of two,
1064 so that it can probably be generated
1066 && GET_CODE (temp3) == CONST_INT
1067 && exact_log2 (INTVAL (temp3)) >= 0))
1068 && (reversep = 0, temp2 == const0_rtx))
1069 || ((BRANCH_COST >= 2
1070 || STORE_FLAG_VALUE == -1
1071 || (STORE_FLAG_VALUE == 1
1072 && GET_CODE (temp2) == CONST_INT
1073 && exact_log2 (INTVAL (temp2)) >= 0))
1074 && temp3 == const0_rtx
1075 && (reversep = can_reverse_comparison_p (temp4, insn)))
1076 || (BRANCH_COST >= 2
1077 && GET_CODE (temp2) == CONST_INT
1078 && GET_CODE (temp3) == CONST_INT
1079 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1080 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1081 && (reversep = can_reverse_comparison_p (temp4,
1083 || BRANCH_COST >= 3)
1086 enum rtx_code code = GET_CODE (temp4);
1087 rtx uval, cval, var = temp1;
1091 /* If necessary, reverse the condition. */
1093 code = reverse_condition (code), uval = temp2, cval = temp3;
1095 uval = temp3, cval = temp2;
1097 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1098 is the constant 1, it is best to just compute the result
1099 directly. If UVAL is constant and STORE_FLAG_VALUE
1100 includes all of its bits, it is best to compute the flag
1101 value unnormalized and `and' it with UVAL. Otherwise,
1102 normalize to -1 and `and' with UVAL. */
1103 normalizep = (cval != const0_rtx ? -1
1104 : (uval == const1_rtx ? 1
1105 : (GET_CODE (uval) == CONST_INT
1106 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1109 /* We will be putting the store-flag insn immediately in
1110 front of the comparison that was originally being done,
1111 so we know all the variables in TEMP4 will be valid.
1112 However, this might be in front of the assignment of
1113 A to VAR. If it is, it would clobber the store-flag
1114 we will be emitting.
1116 Therefore, emit into a temporary which will be copied to
1117 VAR immediately after TEMP. */
1120 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1121 XEXP (temp4, 0), XEXP (temp4, 1),
1123 (code == LTU || code == LEU
1124 || code == GEU || code == GTU),
1134 /* Put the store-flag insns in front of the first insn
1135 used to compute the condition to ensure that we
1136 use the same values of them as the current
1137 comparison. However, the remainder of the insns we
1138 generate will be placed directly in front of the
1139 jump insn, in case any of the pseudos we use
1140 are modified earlier. */
1142 emit_insns_before (seq, temp5);
1146 /* Both CVAL and UVAL are non-zero. */
1147 if (cval != const0_rtx && uval != const0_rtx)
1151 tem1 = expand_and (uval, target, NULL_RTX);
1152 if (GET_CODE (cval) == CONST_INT
1153 && GET_CODE (uval) == CONST_INT
1154 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1158 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1159 target, NULL_RTX, 0);
1160 tem2 = expand_and (cval, tem2,
1161 (GET_CODE (tem2) == REG
1165 /* If we usually make new pseudos, do so here. This
1166 turns out to help machines that have conditional
1168 /* ??? Conditional moves have already been handled.
1169 This may be obsolete. */
1171 if (flag_expensive_optimizations)
1174 target = expand_binop (GET_MODE (var), ior_optab,
1178 else if (normalizep != 1)
1180 /* We know that either CVAL or UVAL is zero. If
1181 UVAL is zero, negate TARGET and `and' with CVAL.
1182 Otherwise, `and' with UVAL. */
1183 if (uval == const0_rtx)
1185 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1186 target, NULL_RTX, 0);
1190 target = expand_and (uval, target,
1191 (GET_CODE (target) == REG
1192 && ! preserve_subexpressions_p ()
1193 ? target : NULL_RTX));
1196 emit_move_insn (var, target);
1200 /* If INSN uses CC0, we must not separate it from the
1201 insn that sets cc0. */
1202 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1203 before = prev_nonnote_insn (before);
1205 emit_insns_before (seq, before);
1208 next = NEXT_INSN (insn);
1213 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1214 old_max_reg = max_reg_num ();
1225 /* If branches are expensive, convert
1226 if (foo) bar++; to bar += (foo != 0);
1227 and similarly for "bar--;"
1229 INSN is the conditional branch around the arithmetic. We set:
1231 TEMP is the arithmetic insn.
1232 TEMP1 is the SET doing the arithmetic.
1233 TEMP2 is the operand being incremented or decremented.
1234 TEMP3 to the condition being tested.
1235 TEMP4 to the earliest insn used to find the condition. */
1237 if ((BRANCH_COST >= 2
1245 && ! reload_completed
1246 && this_is_condjump && ! this_is_simplejump
1247 && (temp = next_nonnote_insn (insn)) != 0
1248 && (temp1 = single_set (temp)) != 0
1249 && (temp2 = SET_DEST (temp1),
1250 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1251 && GET_CODE (SET_SRC (temp1)) == PLUS
1252 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1253 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1254 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1255 && ! side_effects_p (temp2)
1256 && ! may_trap_p (temp2)
1257 /* INSN must either branch to the insn after TEMP or the insn
1258 after TEMP must branch to the same place as INSN. */
1259 && (reallabelprev == temp
1260 || ((temp3 = next_active_insn (temp)) != 0
1261 && simplejump_p (temp3)
1262 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1263 && (temp3 = get_condition (insn, &temp4)) != 0
1264 /* We must be comparing objects whose modes imply the size.
1265 We could handle BLKmode if (1) emit_store_flag could
1266 and (2) we could find the size reliably. */
1267 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1268 && can_reverse_comparison_p (temp3, insn))
1270 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1271 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1275 /* It must be the case that TEMP2 is not modified in the range
1276 [TEMP4, INSN). The one exception we make is if the insn
1277 before INSN sets TEMP2 to something which is also unchanged
1278 in that range. In that case, we can move the initialization
1279 into our sequence. */
1281 if ((temp5 = prev_active_insn (insn)) != 0
1282 && no_labels_between_p (temp5, insn)
1283 && GET_CODE (temp5) == INSN
1284 && (temp6 = single_set (temp5)) != 0
1285 && rtx_equal_p (temp2, SET_DEST (temp6))
1286 && (CONSTANT_P (SET_SRC (temp6))
1287 || GET_CODE (SET_SRC (temp6)) == REG
1288 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1290 emit_insn (PATTERN (temp5));
1292 init = SET_SRC (temp6);
1295 if (CONSTANT_P (init)
1296 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1297 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1298 XEXP (temp3, 0), XEXP (temp3, 1),
1300 (code == LTU || code == LEU
1301 || code == GTU || code == GEU), 1);
1303 /* If we can do the store-flag, do the addition or
1307 target = expand_binop (GET_MODE (temp2),
1308 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1309 ? add_optab : sub_optab),
1310 temp2, target, temp2, 0, OPTAB_WIDEN);
1314 /* Put the result back in temp2 in case it isn't already.
1315 Then replace the jump, possible a CC0-setting insn in
1316 front of the jump, and TEMP, with the sequence we have
1319 if (target != temp2)
1320 emit_move_insn (temp2, target);
1325 emit_insns_before (seq, temp4);
1329 delete_insn (init_insn);
1331 next = NEXT_INSN (insn);
1333 delete_insn (prev_nonnote_insn (insn));
1339 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1340 old_max_reg = max_reg_num ();
1350 /* Simplify if (...) x = 1; else {...} if (x) ...
1351 We recognize this case scanning backwards as well.
1353 TEMP is the assignment to x;
1354 TEMP1 is the label at the head of the second if. */
1355 /* ?? This should call get_condition to find the values being
1356 compared, instead of looking for a COMPARE insn when HAVE_cc0
1357 is not defined. This would allow it to work on the m88k. */
1358 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1359 is not defined and the condition is tested by a separate compare
1360 insn. This is because the code below assumes that the result
1361 of the compare dies in the following branch.
1363 Not only that, but there might be other insns between the
1364 compare and branch whose results are live. Those insns need
1367 A way to fix this is to move the insns at JUMP_LABEL (insn)
1368 to before INSN. If we are running before flow, they will
1369 be deleted if they aren't needed. But this doesn't work
1372 This is really a special-case of jump threading, anyway. The
1373 right thing to do is to replace this and jump threading with
1374 much simpler code in cse.
1376 This code has been turned off in the non-cc0 case in the
1380 else if (this_is_simplejump
1381 /* Safe to skip USE and CLOBBER insns here
1382 since they will not be deleted. */
1383 && (temp = prev_active_insn (insn))
1384 && no_labels_between_p (temp, insn)
1385 && GET_CODE (temp) == INSN
1386 && GET_CODE (PATTERN (temp)) == SET
1387 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1388 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1389 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1390 /* If we find that the next value tested is `x'
1391 (TEMP1 is the insn where this happens), win. */
1392 && GET_CODE (temp1) == INSN
1393 && GET_CODE (PATTERN (temp1)) == SET
1395 /* Does temp1 `tst' the value of x? */
1396 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1397 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1398 && (temp1 = next_nonnote_insn (temp1))
1400 /* Does temp1 compare the value of x against zero? */
1401 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1402 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1403 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1404 == SET_DEST (PATTERN (temp)))
1405 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1406 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1408 && condjump_p (temp1))
1410 /* Get the if_then_else from the condjump. */
1411 rtx choice = SET_SRC (PATTERN (temp1));
1412 if (GET_CODE (choice) == IF_THEN_ELSE)
1414 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1415 rtx val = SET_SRC (PATTERN (temp));
1417 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1421 if (cond == const_true_rtx)
1422 ultimate = XEXP (choice, 1);
1423 else if (cond == const0_rtx)
1424 ultimate = XEXP (choice, 2);
1428 if (ultimate == pc_rtx)
1429 ultimate = get_label_after (temp1);
1430 else if (ultimate && GET_CODE (ultimate) != RETURN)
1431 ultimate = XEXP (ultimate, 0);
1433 if (ultimate && JUMP_LABEL(insn) != ultimate)
1434 changed |= redirect_jump (insn, ultimate);
1440 /* @@ This needs a bit of work before it will be right.
1442 Any type of comparison can be accepted for the first and
1443 second compare. When rewriting the first jump, we must
1444 compute the what conditions can reach label3, and use the
1445 appropriate code. We can not simply reverse/swap the code
1446 of the first jump. In some cases, the second jump must be
1450 < == converts to > ==
1451 < != converts to == >
1454 If the code is written to only accept an '==' test for the second
1455 compare, then all that needs to be done is to swap the condition
1456 of the first branch.
1458 It is questionable whether we want this optimization anyways,
1459 since if the user wrote code like this because he/she knew that
1460 the jump to label1 is taken most of the time, then rewriting
1461 this gives slower code. */
1462 /* @@ This should call get_condition to find the values being
1463 compared, instead of looking for a COMPARE insn when HAVE_cc0
1464 is not defined. This would allow it to work on the m88k. */
1465 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1466 is not defined and the condition is tested by a separate compare
1467 insn. This is because the code below assumes that the result
1468 of the compare dies in the following branch. */
1470 /* Simplify test a ~= b
1484 where ~= is an inequality, e.g. >, and ~~= is the swapped
1487 We recognize this case scanning backwards.
1489 TEMP is the conditional jump to `label2';
1490 TEMP1 is the test for `a == b';
1491 TEMP2 is the conditional jump to `label1';
1492 TEMP3 is the test for `a ~= b'. */
1493 else if (this_is_simplejump
1494 && (temp = prev_active_insn (insn))
1495 && no_labels_between_p (temp, insn)
1496 && condjump_p (temp)
1497 && (temp1 = prev_active_insn (temp))
1498 && no_labels_between_p (temp1, temp)
1499 && GET_CODE (temp1) == INSN
1500 && GET_CODE (PATTERN (temp1)) == SET
1502 && sets_cc0_p (PATTERN (temp1)) == 1
1504 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1505 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1506 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1508 && (temp2 = prev_active_insn (temp1))
1509 && no_labels_between_p (temp2, temp1)
1510 && condjump_p (temp2)
1511 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1512 && (temp3 = prev_active_insn (temp2))
1513 && no_labels_between_p (temp3, temp2)
1514 && GET_CODE (PATTERN (temp3)) == SET
1515 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1516 SET_DEST (PATTERN (temp1)))
1517 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1518 SET_SRC (PATTERN (temp3)))
1519 && ! inequality_comparisons_p (PATTERN (temp))
1520 && inequality_comparisons_p (PATTERN (temp2)))
1522 rtx fallthrough_label = JUMP_LABEL (temp2);
1524 ++LABEL_NUSES (fallthrough_label);
1525 if (swap_jump (temp2, JUMP_LABEL (insn)))
1531 if (--LABEL_NUSES (fallthrough_label) == 0)
1532 delete_insn (fallthrough_label);
1535 /* Simplify if (...) {... x = 1;} if (x) ...
1537 We recognize this case backwards.
1539 TEMP is the test of `x';
1540 TEMP1 is the assignment to `x' at the end of the
1541 previous statement. */
1542 /* @@ This should call get_condition to find the values being
1543 compared, instead of looking for a COMPARE insn when HAVE_cc0
1544 is not defined. This would allow it to work on the m88k. */
1545 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1546 is not defined and the condition is tested by a separate compare
1547 insn. This is because the code below assumes that the result
1548 of the compare dies in the following branch. */
1550 /* ??? This has to be turned off. The problem is that the
1551 unconditional jump might indirectly end up branching to the
1552 label between TEMP1 and TEMP. We can't detect this, in general,
1553 since it may become a jump to there after further optimizations.
1554 If that jump is done, it will be deleted, so we will retry
1555 this optimization in the next pass, thus an infinite loop.
1557 The present code prevents this by putting the jump after the
1558 label, but this is not logically correct. */
1560 else if (this_is_condjump
1561 /* Safe to skip USE and CLOBBER insns here
1562 since they will not be deleted. */
1563 && (temp = prev_active_insn (insn))
1564 && no_labels_between_p (temp, insn)
1565 && GET_CODE (temp) == INSN
1566 && GET_CODE (PATTERN (temp)) == SET
1568 && sets_cc0_p (PATTERN (temp)) == 1
1569 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1571 /* Temp must be a compare insn, we can not accept a register
1572 to register move here, since it may not be simply a
1574 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1575 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1576 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1577 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1578 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1580 /* May skip USE or CLOBBER insns here
1581 for checking for opportunity, since we
1582 take care of them later. */
1583 && (temp1 = prev_active_insn (temp))
1584 && GET_CODE (temp1) == INSN
1585 && GET_CODE (PATTERN (temp1)) == SET
1587 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1589 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1590 == SET_DEST (PATTERN (temp1)))
1592 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1593 /* If this isn't true, cse will do the job. */
1594 && ! no_labels_between_p (temp1, temp))
1596 /* Get the if_then_else from the condjump. */
1597 rtx choice = SET_SRC (PATTERN (insn));
1598 if (GET_CODE (choice) == IF_THEN_ELSE
1599 && (GET_CODE (XEXP (choice, 0)) == EQ
1600 || GET_CODE (XEXP (choice, 0)) == NE))
1602 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1607 /* Get the place that condjump will jump to
1608 if it is reached from here. */
1609 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1611 ultimate = XEXP (choice, 1);
1613 ultimate = XEXP (choice, 2);
1614 /* Get it as a CODE_LABEL. */
1615 if (ultimate == pc_rtx)
1616 ultimate = get_label_after (insn);
1618 /* Get the label out of the LABEL_REF. */
1619 ultimate = XEXP (ultimate, 0);
1621 /* Insert the jump immediately before TEMP, specifically
1622 after the label that is between TEMP1 and TEMP. */
1623 last_insn = PREV_INSN (temp);
1625 /* If we would be branching to the next insn, the jump
1626 would immediately be deleted and the re-inserted in
1627 a subsequent pass over the code. So don't do anything
1629 if (next_active_insn (last_insn)
1630 != next_active_insn (ultimate))
1632 emit_barrier_after (last_insn);
1633 p = emit_jump_insn_after (gen_jump (ultimate),
1635 JUMP_LABEL (p) = ultimate;
1636 ++LABEL_NUSES (ultimate);
1637 if (INSN_UID (ultimate) < max_jump_chain
1638 && INSN_CODE (p) < max_jump_chain)
1640 jump_chain[INSN_UID (p)]
1641 = jump_chain[INSN_UID (ultimate)];
1642 jump_chain[INSN_UID (ultimate)] = p;
1650 /* Detect a conditional jump going to the same place
1651 as an immediately following unconditional jump. */
1652 else if (this_is_condjump
1653 && (temp = next_active_insn (insn)) != 0
1654 && simplejump_p (temp)
1655 && (next_active_insn (JUMP_LABEL (insn))
1656 == next_active_insn (JUMP_LABEL (temp))))
1660 /* ??? Optional. Disables some optimizations, but makes
1661 gcov output more accurate with -O. */
1662 if (flag_test_coverage && !reload_completed)
1663 for (tem = insn; tem != temp; tem = NEXT_INSN (tem))
1664 if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0)
1675 /* Detect a conditional jump jumping over an unconditional trap. */
1677 && this_is_condjump && ! this_is_simplejump
1678 && reallabelprev != 0
1679 && GET_CODE (reallabelprev) == INSN
1680 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
1681 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
1682 && prev_active_insn (reallabelprev) == insn
1683 && no_labels_between_p (insn, reallabelprev)
1684 && (temp2 = get_condition (insn, &temp4))
1685 && can_reverse_comparison_p (temp2, insn))
1687 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
1688 XEXP (temp2, 0), XEXP (temp2, 1),
1689 TRAP_CODE (PATTERN (reallabelprev)));
1693 emit_insn_before (new, temp4);
1694 delete_insn (reallabelprev);
1700 /* Detect a jump jumping to an unconditional trap. */
1701 else if (HAVE_trap && this_is_condjump
1702 && (temp = next_active_insn (JUMP_LABEL (insn)))
1703 && GET_CODE (temp) == INSN
1704 && GET_CODE (PATTERN (temp)) == TRAP_IF
1705 && (this_is_simplejump
1706 || (temp2 = get_condition (insn, &temp4))))
1708 rtx tc = TRAP_CONDITION (PATTERN (temp));
1710 if (tc == const_true_rtx
1711 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
1714 /* Replace an unconditional jump to a trap with a trap. */
1715 if (this_is_simplejump)
1717 emit_barrier_after (emit_insn_before (gen_trap (), insn));
1722 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
1724 TRAP_CODE (PATTERN (temp)));
1727 emit_insn_before (new, temp4);
1733 /* If the trap condition and jump condition are mutually
1734 exclusive, redirect the jump to the following insn. */
1735 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
1736 && ! this_is_simplejump
1737 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
1738 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
1739 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
1740 && redirect_jump (insn, get_label_after (temp)))
1748 /* Detect a conditional jump jumping over an unconditional jump. */
1750 else if ((this_is_condjump || this_is_condjump_in_parallel)
1751 && ! this_is_simplejump
1752 && reallabelprev != 0
1753 && GET_CODE (reallabelprev) == JUMP_INSN
1754 && prev_active_insn (reallabelprev) == insn
1755 && no_labels_between_p (insn, reallabelprev)
1756 && simplejump_p (reallabelprev))
1758 /* When we invert the unconditional jump, we will be
1759 decrementing the usage count of its old label.
1760 Make sure that we don't delete it now because that
1761 might cause the following code to be deleted. */
1762 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1763 rtx prev_label = JUMP_LABEL (insn);
1766 ++LABEL_NUSES (prev_label);
1768 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1770 /* It is very likely that if there are USE insns before
1771 this jump, they hold REG_DEAD notes. These REG_DEAD
1772 notes are no longer valid due to this optimization,
1773 and will cause the life-analysis that following passes
1774 (notably delayed-branch scheduling) to think that
1775 these registers are dead when they are not.
1777 To prevent this trouble, we just remove the USE insns
1778 from the insn chain. */
1780 while (prev_uses && GET_CODE (prev_uses) == INSN
1781 && GET_CODE (PATTERN (prev_uses)) == USE)
1783 rtx useless = prev_uses;
1784 prev_uses = prev_nonnote_insn (prev_uses);
1785 delete_insn (useless);
1788 delete_insn (reallabelprev);
1793 /* We can now safely delete the label if it is unreferenced
1794 since the delete_insn above has deleted the BARRIER. */
1795 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1796 delete_insn (prev_label);
1801 /* Detect a jump to a jump. */
1803 nlabel = follow_jumps (JUMP_LABEL (insn));
1804 if (nlabel != JUMP_LABEL (insn)
1805 && redirect_jump (insn, nlabel))
1811 /* Look for if (foo) bar; else break; */
1812 /* The insns look like this:
1813 insn = condjump label1;
1814 ...range1 (some insns)...
1817 ...range2 (some insns)...
1818 jump somewhere unconditionally
1821 rtx label1 = next_label (insn);
1822 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1823 /* Don't do this optimization on the first round, so that
1824 jump-around-a-jump gets simplified before we ask here
1825 whether a jump is unconditional.
1827 Also don't do it when we are called after reload since
1828 it will confuse reorg. */
1830 && (reload_completed ? ! flag_delayed_branch : 1)
1831 /* Make sure INSN is something we can invert. */
1832 && condjump_p (insn)
1834 && JUMP_LABEL (insn) == label1
1835 && LABEL_NUSES (label1) == 1
1836 && GET_CODE (range1end) == JUMP_INSN
1837 && simplejump_p (range1end))
1839 rtx label2 = next_label (label1);
1840 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1841 if (range1end != range2end
1842 && JUMP_LABEL (range1end) == label2
1843 && GET_CODE (range2end) == JUMP_INSN
1844 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1845 /* Invert the jump condition, so we
1846 still execute the same insns in each case. */
1847 && invert_jump (insn, label1))
1849 rtx range1beg = next_active_insn (insn);
1850 rtx range2beg = next_active_insn (label1);
1851 rtx range1after, range2after;
1852 rtx range1before, range2before;
1855 /* Include in each range any notes before it, to be
1856 sure that we get the line number note if any, even
1857 if there are other notes here. */
1858 while (PREV_INSN (range1beg)
1859 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1860 range1beg = PREV_INSN (range1beg);
1862 while (PREV_INSN (range2beg)
1863 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1864 range2beg = PREV_INSN (range2beg);
1866 /* Don't move NOTEs for blocks or loops; shift them
1867 outside the ranges, where they'll stay put. */
1868 range1beg = squeeze_notes (range1beg, range1end);
1869 range2beg = squeeze_notes (range2beg, range2end);
1871 /* Get current surrounds of the 2 ranges. */
1872 range1before = PREV_INSN (range1beg);
1873 range2before = PREV_INSN (range2beg);
1874 range1after = NEXT_INSN (range1end);
1875 range2after = NEXT_INSN (range2end);
1877 /* Splice range2 where range1 was. */
1878 NEXT_INSN (range1before) = range2beg;
1879 PREV_INSN (range2beg) = range1before;
1880 NEXT_INSN (range2end) = range1after;
1881 PREV_INSN (range1after) = range2end;
1882 /* Splice range1 where range2 was. */
1883 NEXT_INSN (range2before) = range1beg;
1884 PREV_INSN (range1beg) = range2before;
1885 NEXT_INSN (range1end) = range2after;
1886 PREV_INSN (range2after) = range1end;
1888 /* Check for a loop end note between the end of
1889 range2, and the next code label. If there is one,
1890 then what we have really seen is
1891 if (foo) break; end_of_loop;
1892 and moved the break sequence outside the loop.
1893 We must move the LOOP_END note to where the
1894 loop really ends now, or we will confuse loop
1895 optimization. Stop if we find a LOOP_BEG note
1896 first, since we don't want to move the LOOP_END
1897 note in that case. */
1898 for (;range2after != label2; range2after = rangenext)
1900 rangenext = NEXT_INSN (range2after);
1901 if (GET_CODE (range2after) == NOTE)
1903 if (NOTE_LINE_NUMBER (range2after)
1904 == NOTE_INSN_LOOP_END)
1906 NEXT_INSN (PREV_INSN (range2after))
1908 PREV_INSN (rangenext)
1909 = PREV_INSN (range2after);
1910 PREV_INSN (range2after)
1911 = PREV_INSN (range1beg);
1912 NEXT_INSN (range2after) = range1beg;
1913 NEXT_INSN (PREV_INSN (range1beg))
1915 PREV_INSN (range1beg) = range2after;
1917 else if (NOTE_LINE_NUMBER (range2after)
1918 == NOTE_INSN_LOOP_BEG)
1928 /* Now that the jump has been tensioned,
1929 try cross jumping: check for identical code
1930 before the jump and before its target label. */
1932 /* First, cross jumping of conditional jumps: */
1934 if (cross_jump && condjump_p (insn))
1936 rtx newjpos, newlpos;
1937 rtx x = prev_real_insn (JUMP_LABEL (insn));
1939 /* A conditional jump may be crossjumped
1940 only if the place it jumps to follows
1941 an opposing jump that comes back here. */
1943 if (x != 0 && ! jump_back_p (x, insn))
1944 /* We have no opposing jump;
1945 cannot cross jump this insn. */
1949 /* TARGET is nonzero if it is ok to cross jump
1950 to code before TARGET. If so, see if matches. */
1952 find_cross_jump (insn, x, 2,
1953 &newjpos, &newlpos);
1957 do_cross_jump (insn, newjpos, newlpos);
1958 /* Make the old conditional jump
1959 into an unconditional one. */
1960 SET_SRC (PATTERN (insn))
1961 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
1962 INSN_CODE (insn) = -1;
1963 emit_barrier_after (insn);
1964 /* Add to jump_chain unless this is a new label
1965 whose UID is too large. */
1966 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1968 jump_chain[INSN_UID (insn)]
1969 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1970 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1977 /* Cross jumping of unconditional jumps:
1978 a few differences. */
1980 if (cross_jump && simplejump_p (insn))
1982 rtx newjpos, newlpos;
1987 /* TARGET is nonzero if it is ok to cross jump
1988 to code before TARGET. If so, see if matches. */
1989 find_cross_jump (insn, JUMP_LABEL (insn), 1,
1990 &newjpos, &newlpos);
1992 /* If cannot cross jump to code before the label,
1993 see if we can cross jump to another jump to
1995 /* Try each other jump to this label. */
1996 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
1997 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1998 target != 0 && newjpos == 0;
1999 target = jump_chain[INSN_UID (target)])
2001 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2002 /* Ignore TARGET if it's deleted. */
2003 && ! INSN_DELETED_P (target))
2004 find_cross_jump (insn, target, 2,
2005 &newjpos, &newlpos);
2009 do_cross_jump (insn, newjpos, newlpos);
2015 /* This code was dead in the previous jump.c! */
2016 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2018 /* Return insns all "jump to the same place"
2019 so we can cross-jump between any two of them. */
2021 rtx newjpos, newlpos, target;
2025 /* If cannot cross jump to code before the label,
2026 see if we can cross jump to another jump to
2028 /* Try each other jump to this label. */
2029 for (target = jump_chain[0];
2030 target != 0 && newjpos == 0;
2031 target = jump_chain[INSN_UID (target)])
2033 && ! INSN_DELETED_P (target)
2034 && GET_CODE (PATTERN (target)) == RETURN)
2035 find_cross_jump (insn, target, 2,
2036 &newjpos, &newlpos);
2040 do_cross_jump (insn, newjpos, newlpos);
2051 /* Delete extraneous line number notes.
2052 Note that two consecutive notes for different lines are not really
2053 extraneous. There should be some indication where that line belonged,
2054 even if it became empty. */
2059 for (insn = f; insn; insn = NEXT_INSN (insn))
2060 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2062 /* Delete this note if it is identical to previous note. */
2064 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2065 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2078 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2079 in front of it. If the machine allows it at this point (we might be
2080 after reload for a leaf routine), it will improve optimization for it
2081 to be there. We do this both here and at the start of this pass since
2082 the RETURN might have been deleted by some of our optimizations. */
2083 insn = get_last_insn ();
2084 while (insn && GET_CODE (insn) == NOTE)
2085 insn = PREV_INSN (insn);
2087 if (insn && GET_CODE (insn) != BARRIER)
2089 emit_jump_insn (gen_return ());
2095 /* CAN_REACH_END is persistent for each function. Once set it should
2096 not be cleared. This is especially true for the case where we
2097 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
2098 the front-end before compiling each function. */
2099 if (calculate_can_reach_end (last_insn, 0, 1))
2102 /* Show JUMP_CHAIN no longer valid. */
2106 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2107 notes whose labels don't occur in the insn any more. Returns the
2108 largest INSN_UID found. */
2113 int largest_uid = 0;
2116 for (insn = f; insn; insn = NEXT_INSN (insn))
2118 if (GET_CODE (insn) == CODE_LABEL)
2119 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
2120 else if (GET_CODE (insn) == JUMP_INSN)
2121 JUMP_LABEL (insn) = 0;
2122 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2126 for (note = REG_NOTES (insn); note; note = next)
2128 next = XEXP (note, 1);
2129 if (REG_NOTE_KIND (note) == REG_LABEL
2130 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
2131 remove_note (insn, note);
2134 if (INSN_UID (insn) > largest_uid)
2135 largest_uid = INSN_UID (insn);
2141 /* Delete insns following barriers, up to next label.
2143 Also delete no-op jumps created by gcse. */
2145 delete_barrier_successors (f)
2150 for (insn = f; insn;)
2152 if (GET_CODE (insn) == BARRIER)
2154 insn = NEXT_INSN (insn);
2155 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
2157 if (GET_CODE (insn) == NOTE
2158 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2159 insn = NEXT_INSN (insn);
2161 insn = delete_insn (insn);
2163 /* INSN is now the code_label. */
2165 /* Also remove (set (pc) (pc)) insns which can be created by
2166 gcse. We eliminate such insns now to avoid having them
2167 cause problems later. */
2168 else if (GET_CODE (insn) == JUMP_INSN
2169 && SET_SRC (PATTERN (insn)) == pc_rtx
2170 && SET_DEST (PATTERN (insn)) == pc_rtx)
2171 insn = delete_insn (insn);
2174 insn = NEXT_INSN (insn);
2178 /* Mark the label each jump jumps to.
2179 Combine consecutive labels, and count uses of labels.
2181 For each label, make a chain (using `jump_chain')
2182 of all the *unconditional* jumps that jump to it;
2183 also make a chain of all returns.
2185 CROSS_JUMP indicates whether we are doing cross jumping
2186 and if we are whether we will be paying attention to
2187 death notes or not. */
2190 mark_all_labels (f, cross_jump)
2196 for (insn = f; insn; insn = NEXT_INSN (insn))
2197 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2199 mark_jump_label (PATTERN (insn), insn, cross_jump);
2200 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
2202 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2204 jump_chain[INSN_UID (insn)]
2205 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2206 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2208 if (GET_CODE (PATTERN (insn)) == RETURN)
2210 jump_chain[INSN_UID (insn)] = jump_chain[0];
2211 jump_chain[0] = insn;
2217 /* Delete all labels already not referenced.
2218 Also find and return the last insn. */
2221 delete_unreferenced_labels (f)
2224 rtx final = NULL_RTX;
2227 for (insn = f; insn; )
2229 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
2230 insn = delete_insn (insn);
2234 insn = NEXT_INSN (insn);
2241 /* Delete various simple forms of moves which have no necessary
2245 delete_noop_moves (f)
2250 for (insn = f; insn; )
2252 next = NEXT_INSN (insn);
2254 if (GET_CODE (insn) == INSN)
2256 register rtx body = PATTERN (insn);
2258 /* Combine stack_adjusts with following push_insns. */
2259 #ifdef PUSH_ROUNDING
2260 if (GET_CODE (body) == SET
2261 && SET_DEST (body) == stack_pointer_rtx
2262 && GET_CODE (SET_SRC (body)) == PLUS
2263 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
2264 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
2265 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
2268 rtx stack_adjust_insn = insn;
2269 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
2270 int total_pushed = 0;
2273 /* Find all successive push insns. */
2275 /* Don't convert more than three pushes;
2276 that starts adding too many displaced addresses
2277 and the whole thing starts becoming a losing
2282 p = next_nonnote_insn (p);
2283 if (p == 0 || GET_CODE (p) != INSN)
2285 pbody = PATTERN (p);
2286 if (GET_CODE (pbody) != SET)
2288 dest = SET_DEST (pbody);
2289 /* Allow a no-op move between the adjust and the push. */
2290 if (GET_CODE (dest) == REG
2291 && GET_CODE (SET_SRC (pbody)) == REG
2292 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2294 if (! (GET_CODE (dest) == MEM
2295 && GET_CODE (XEXP (dest, 0)) == POST_INC
2296 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2299 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
2300 > stack_adjust_amount)
2302 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2305 /* Discard the amount pushed from the stack adjust;
2306 maybe eliminate it entirely. */
2307 if (total_pushed >= stack_adjust_amount)
2309 delete_computation (stack_adjust_insn);
2310 total_pushed = stack_adjust_amount;
2313 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
2314 = GEN_INT (stack_adjust_amount - total_pushed);
2316 /* Change the appropriate push insns to ordinary stores. */
2318 while (total_pushed > 0)
2321 p = next_nonnote_insn (p);
2322 if (GET_CODE (p) != INSN)
2324 pbody = PATTERN (p);
2325 if (GET_CODE (pbody) != SET)
2327 dest = SET_DEST (pbody);
2328 /* Allow a no-op move between the adjust and the push. */
2329 if (GET_CODE (dest) == REG
2330 && GET_CODE (SET_SRC (pbody)) == REG
2331 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2333 if (! (GET_CODE (dest) == MEM
2334 && GET_CODE (XEXP (dest, 0)) == POST_INC
2335 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2337 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2338 /* If this push doesn't fully fit in the space
2339 of the stack adjust that we deleted,
2340 make another stack adjust here for what we
2341 didn't use up. There should be peepholes
2342 to recognize the resulting sequence of insns. */
2343 if (total_pushed < 0)
2345 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
2346 GEN_INT (- total_pushed)),
2351 = plus_constant (stack_pointer_rtx, total_pushed);
2356 /* Detect and delete no-op move instructions
2357 resulting from not allocating a parameter in a register. */
2359 if (GET_CODE (body) == SET
2360 && (SET_DEST (body) == SET_SRC (body)
2361 || (GET_CODE (SET_DEST (body)) == MEM
2362 && GET_CODE (SET_SRC (body)) == MEM
2363 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
2364 && ! (GET_CODE (SET_DEST (body)) == MEM
2365 && MEM_VOLATILE_P (SET_DEST (body)))
2366 && ! (GET_CODE (SET_SRC (body)) == MEM
2367 && MEM_VOLATILE_P (SET_SRC (body))))
2368 delete_computation (insn);
2370 /* Detect and ignore no-op move instructions
2371 resulting from smart or fortuitous register allocation. */
2373 else if (GET_CODE (body) == SET)
2375 int sreg = true_regnum (SET_SRC (body));
2376 int dreg = true_regnum (SET_DEST (body));
2378 if (sreg == dreg && sreg >= 0)
2380 else if (sreg >= 0 && dreg >= 0)
2383 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
2384 sreg, NULL_PTR, dreg,
2385 GET_MODE (SET_SRC (body)));
2388 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
2390 /* DREG may have been the target of a REG_DEAD note in
2391 the insn which makes INSN redundant. If so, reorg
2392 would still think it is dead. So search for such a
2393 note and delete it if we find it. */
2394 if (! find_regno_note (insn, REG_UNUSED, dreg))
2395 for (trial = prev_nonnote_insn (insn);
2396 trial && GET_CODE (trial) != CODE_LABEL;
2397 trial = prev_nonnote_insn (trial))
2398 if (find_regno_note (trial, REG_DEAD, dreg))
2400 remove_death (dreg, trial);
2404 /* Deleting insn could lose a death-note for SREG. */
2405 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
2407 /* Change this into a USE so that we won't emit
2408 code for it, but still can keep the note. */
2410 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
2411 INSN_CODE (insn) = -1;
2412 /* Remove all reg notes but the REG_DEAD one. */
2413 REG_NOTES (insn) = trial;
2414 XEXP (trial, 1) = NULL_RTX;
2420 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
2421 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
2423 GET_MODE (SET_DEST (body))))
2425 /* This handles the case where we have two consecutive
2426 assignments of the same constant to pseudos that didn't
2427 get a hard reg. Each SET from the constant will be
2428 converted into a SET of the spill register and an
2429 output reload will be made following it. This produces
2430 two loads of the same constant into the same spill
2435 /* Look back for a death note for the first reg.
2436 If there is one, it is no longer accurate. */
2437 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
2439 if ((GET_CODE (in_insn) == INSN
2440 || GET_CODE (in_insn) == JUMP_INSN)
2441 && find_regno_note (in_insn, REG_DEAD, dreg))
2443 remove_death (dreg, in_insn);
2446 in_insn = PREV_INSN (in_insn);
2449 /* Delete the second load of the value. */
2453 else if (GET_CODE (body) == PARALLEL)
2455 /* If each part is a set between two identical registers or
2456 a USE or CLOBBER, delete the insn. */
2460 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
2462 tem = XVECEXP (body, 0, i);
2463 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
2466 if (GET_CODE (tem) != SET
2467 || (sreg = true_regnum (SET_SRC (tem))) < 0
2468 || (dreg = true_regnum (SET_DEST (tem))) < 0
2476 /* Also delete insns to store bit fields if they are no-ops. */
2477 /* Not worth the hair to detect this in the big-endian case. */
2478 else if (! BYTES_BIG_ENDIAN
2479 && GET_CODE (body) == SET
2480 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
2481 && XEXP (SET_DEST (body), 2) == const0_rtx
2482 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
2483 && ! (GET_CODE (SET_SRC (body)) == MEM
2484 && MEM_VOLATILE_P (SET_SRC (body))))
2491 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2492 If so indicate that this function can drop off the end by returning
2495 CHECK_DELETED indicates whether we must check if the note being
2496 searched for has the deleted flag set.
2498 DELETE_FINAL_NOTE indicates whether we should delete the note
2502 calculate_can_reach_end (last, check_deleted, delete_final_note)
2505 int delete_final_note;
2510 while (insn != NULL_RTX)
2514 /* One label can follow the end-note: the return label. */
2515 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2517 /* Ordinary insns can follow it if returning a structure. */
2518 else if (GET_CODE (insn) == INSN)
2520 /* If machine uses explicit RETURN insns, no epilogue,
2521 then one of them follows the note. */
2522 else if (GET_CODE (insn) == JUMP_INSN
2523 && GET_CODE (PATTERN (insn)) == RETURN)
2525 /* A barrier can follow the return insn. */
2526 else if (GET_CODE (insn) == BARRIER)
2528 /* Other kinds of notes can follow also. */
2529 else if (GET_CODE (insn) == NOTE
2530 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2536 insn = PREV_INSN (insn);
2539 /* See if we backed up to the appropriate type of note. */
2540 if (insn != NULL_RTX
2541 && GET_CODE (insn) == NOTE
2542 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
2543 && (check_deleted == 0
2544 || ! INSN_DELETED_P (insn)))
2546 if (delete_final_note)
2554 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2555 jump. Assume that this unconditional jump is to the exit test code. If
2556 the code is sufficiently simple, make a copy of it before INSN,
2557 followed by a jump to the exit of the loop. Then delete the unconditional
2560 Return 1 if we made the change, else 0.
2562 This is only safe immediately after a regscan pass because it uses the
2563 values of regno_first_uid and regno_last_uid. */
2566 duplicate_loop_exit_test (loop_start)
2569 rtx insn, set, reg, p, link;
2572 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2574 int max_reg = max_reg_num ();
2577 /* Scan the exit code. We do not perform this optimization if any insn:
2581 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2582 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2583 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2586 We also do not do this if we find an insn with ASM_OPERANDS. While
2587 this restriction should not be necessary, copying an insn with
2588 ASM_OPERANDS can confuse asm_noperands in some cases.
2590 Also, don't do this if the exit code is more than 20 insns. */
2592 for (insn = exitcode;
2594 && ! (GET_CODE (insn) == NOTE
2595 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2596 insn = NEXT_INSN (insn))
2598 switch (GET_CODE (insn))
2604 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2605 a jump immediately after the loop start that branches outside
2606 the loop but within an outer loop, near the exit test.
2607 If we copied this exit test and created a phony
2608 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2609 before the exit test look like these could be safely moved
2610 out of the loop even if they actually may be never executed.
2611 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2613 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2614 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2618 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2619 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
2620 /* If we were to duplicate this code, we would not move
2621 the BLOCK notes, and so debugging the moved code would
2622 be difficult. Thus, we only move the code with -O2 or
2629 /* The code below would grossly mishandle REG_WAS_0 notes,
2630 so get rid of them here. */
2631 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
2632 remove_note (insn, p);
2633 if (++num_insns > 20
2634 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2635 || find_reg_note (insn, REG_LIBCALL, NULL_RTX)
2636 || asm_noperands (PATTERN (insn)) > 0)
2644 /* Unless INSN is zero, we can do the optimization. */
2650 /* See if any insn sets a register only used in the loop exit code and
2651 not a user variable. If so, replace it with a new register. */
2652 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2653 if (GET_CODE (insn) == INSN
2654 && (set = single_set (insn)) != 0
2655 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2656 || (GET_CODE (reg) == SUBREG
2657 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2658 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2659 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2661 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2662 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2667 /* We can do the replacement. Allocate reg_map if this is the
2668 first replacement we found. */
2671 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2672 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2675 REG_LOOP_TEST_P (reg) = 1;
2677 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2681 /* Now copy each insn. */
2682 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2683 switch (GET_CODE (insn))
2686 copy = emit_barrier_before (loop_start);
2689 /* Only copy line-number notes. */
2690 if (NOTE_LINE_NUMBER (insn) >= 0)
2692 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2693 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2698 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2700 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2702 mark_jump_label (PATTERN (copy), copy, 0);
2704 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2706 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2707 if (REG_NOTE_KIND (link) != REG_LABEL)
2709 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2712 if (reg_map && REG_NOTES (copy))
2713 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2717 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2719 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2720 mark_jump_label (PATTERN (copy), copy, 0);
2721 if (REG_NOTES (insn))
2723 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2725 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2728 /* If this is a simple jump, add it to the jump chain. */
2730 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2731 && simplejump_p (copy))
2733 jump_chain[INSN_UID (copy)]
2734 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2735 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2743 /* Now clean up by emitting a jump to the end label and deleting the jump
2744 at the start of the loop. */
2745 if (! copy || GET_CODE (copy) != BARRIER)
2747 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2749 mark_jump_label (PATTERN (copy), copy, 0);
2750 if (INSN_UID (copy) < max_jump_chain
2751 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2753 jump_chain[INSN_UID (copy)]
2754 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2755 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2757 emit_barrier_before (loop_start);
2760 /* Mark the exit code as the virtual top of the converted loop. */
2761 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2763 delete_insn (next_nonnote_insn (loop_start));
2768 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2769 loop-end notes between START and END out before START. Assume that
2770 END is not such a note. START may be such a note. Returns the value
2771 of the new starting insn, which may be different if the original start
2775 squeeze_notes (start, end)
2781 for (insn = start; insn != end; insn = next)
2783 next = NEXT_INSN (insn);
2784 if (GET_CODE (insn) == NOTE
2785 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2786 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2787 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2788 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2789 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2790 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2796 rtx prev = PREV_INSN (insn);
2797 PREV_INSN (insn) = PREV_INSN (start);
2798 NEXT_INSN (insn) = start;
2799 NEXT_INSN (PREV_INSN (insn)) = insn;
2800 PREV_INSN (NEXT_INSN (insn)) = insn;
2801 NEXT_INSN (prev) = next;
2802 PREV_INSN (next) = prev;
2810 /* Compare the instructions before insn E1 with those before E2
2811 to find an opportunity for cross jumping.
2812 (This means detecting identical sequences of insns followed by
2813 jumps to the same place, or followed by a label and a jump
2814 to that label, and replacing one with a jump to the other.)
2816 Assume E1 is a jump that jumps to label E2
2817 (that is not always true but it might as well be).
2818 Find the longest possible equivalent sequences
2819 and store the first insns of those sequences into *F1 and *F2.
2820 Store zero there if no equivalent preceding instructions are found.
2822 We give up if we find a label in stream 1.
2823 Actually we could transfer that label into stream 2. */
2826 find_cross_jump (e1, e2, minimum, f1, f2)
2831 register rtx i1 = e1, i2 = e2;
2832 register rtx p1, p2;
2835 rtx last1 = 0, last2 = 0;
2836 rtx afterlast1 = 0, afterlast2 = 0;
2843 i1 = prev_nonnote_insn (i1);
2845 i2 = PREV_INSN (i2);
2846 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2847 i2 = PREV_INSN (i2);
2852 /* Don't allow the range of insns preceding E1 or E2
2853 to include the other (E2 or E1). */
2854 if (i2 == e1 || i1 == e2)
2857 /* If we will get to this code by jumping, those jumps will be
2858 tensioned to go directly to the new label (before I2),
2859 so this cross-jumping won't cost extra. So reduce the minimum. */
2860 if (GET_CODE (i1) == CODE_LABEL)
2866 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2869 /* Avoid moving insns across EH regions if either of the insns
2872 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
2873 && !in_same_eh_region (i1, i2))
2879 /* If this is a CALL_INSN, compare register usage information.
2880 If we don't check this on stack register machines, the two
2881 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2882 numbers of stack registers in the same basic block.
2883 If we don't check this on machines with delay slots, a delay slot may
2884 be filled that clobbers a parameter expected by the subroutine.
2886 ??? We take the simple route for now and assume that if they're
2887 equal, they were constructed identically. */
2889 if (GET_CODE (i1) == CALL_INSN
2890 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2891 CALL_INSN_FUNCTION_USAGE (i2)))
2895 /* If cross_jump_death_matters is not 0, the insn's mode
2896 indicates whether or not the insn contains any stack-like
2899 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
2901 /* If register stack conversion has already been done, then
2902 death notes must also be compared before it is certain that
2903 the two instruction streams match. */
2906 HARD_REG_SET i1_regset, i2_regset;
2908 CLEAR_HARD_REG_SET (i1_regset);
2909 CLEAR_HARD_REG_SET (i2_regset);
2911 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2912 if (REG_NOTE_KIND (note) == REG_DEAD
2913 && STACK_REG_P (XEXP (note, 0)))
2914 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2916 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2917 if (REG_NOTE_KIND (note) == REG_DEAD
2918 && STACK_REG_P (XEXP (note, 0)))
2919 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2921 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2930 /* Don't allow old-style asm or volatile extended asms to be accepted
2931 for cross jumping purposes. It is conceptually correct to allow
2932 them, since cross-jumping preserves the dynamic instruction order
2933 even though it is changing the static instruction order. However,
2934 if an asm is being used to emit an assembler pseudo-op, such as
2935 the MIPS `.set reorder' pseudo-op, then the static instruction order
2936 matters and it must be preserved. */
2937 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
2938 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
2939 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
2942 if (lose || GET_CODE (p1) != GET_CODE (p2)
2943 || ! rtx_renumbered_equal_p (p1, p2))
2945 /* The following code helps take care of G++ cleanups. */
2949 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2950 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2951 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2952 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2953 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2954 /* If the equivalences are not to a constant, they may
2955 reference pseudos that no longer exist, so we can't
2957 && CONSTANT_P (XEXP (equiv1, 0))
2958 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2960 rtx s1 = single_set (i1);
2961 rtx s2 = single_set (i2);
2962 if (s1 != 0 && s2 != 0
2963 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2965 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2966 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2967 if (! rtx_renumbered_equal_p (p1, p2))
2969 else if (apply_change_group ())
2974 /* Insns fail to match; cross jumping is limited to the following
2978 /* Don't allow the insn after a compare to be shared by
2979 cross-jumping unless the compare is also shared.
2980 Here, if either of these non-matching insns is a compare,
2981 exclude the following insn from possible cross-jumping. */
2982 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2983 last1 = afterlast1, last2 = afterlast2, ++minimum;
2986 /* If cross-jumping here will feed a jump-around-jump
2987 optimization, this jump won't cost extra, so reduce
2989 if (GET_CODE (i1) == JUMP_INSN
2991 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2997 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2999 /* Ok, this insn is potentially includable in a cross-jump here. */
3000 afterlast1 = last1, afterlast2 = last2;
3001 last1 = i1, last2 = i2, --minimum;
3005 if (minimum <= 0 && last1 != 0 && last1 != e1)
3006 *f1 = last1, *f2 = last2;
3010 do_cross_jump (insn, newjpos, newlpos)
3011 rtx insn, newjpos, newlpos;
3013 /* Find an existing label at this point
3014 or make a new one if there is none. */
3015 register rtx label = get_label_before (newlpos);
3017 /* Make the same jump insn jump to the new point. */
3018 if (GET_CODE (PATTERN (insn)) == RETURN)
3020 /* Remove from jump chain of returns. */
3021 delete_from_jump_chain (insn);
3022 /* Change the insn. */
3023 PATTERN (insn) = gen_jump (label);
3024 INSN_CODE (insn) = -1;
3025 JUMP_LABEL (insn) = label;
3026 LABEL_NUSES (label)++;
3027 /* Add to new the jump chain. */
3028 if (INSN_UID (label) < max_jump_chain
3029 && INSN_UID (insn) < max_jump_chain)
3031 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
3032 jump_chain[INSN_UID (label)] = insn;
3036 redirect_jump (insn, label);
3038 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
3039 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
3040 the NEWJPOS stream. */
3042 while (newjpos != insn)
3046 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
3047 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
3048 || REG_NOTE_KIND (lnote) == REG_EQUIV)
3049 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
3050 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
3051 remove_note (newlpos, lnote);
3053 delete_insn (newjpos);
3054 newjpos = next_real_insn (newjpos);
3055 newlpos = next_real_insn (newlpos);
3059 /* Return the label before INSN, or put a new label there. */
3062 get_label_before (insn)
3067 /* Find an existing label at this point
3068 or make a new one if there is none. */
3069 label = prev_nonnote_insn (insn);
3071 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3073 rtx prev = PREV_INSN (insn);
3075 label = gen_label_rtx ();
3076 emit_label_after (label, prev);
3077 LABEL_NUSES (label) = 0;
3082 /* Return the label after INSN, or put a new label there. */
3085 get_label_after (insn)
3090 /* Find an existing label at this point
3091 or make a new one if there is none. */
3092 label = next_nonnote_insn (insn);
3094 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3096 label = gen_label_rtx ();
3097 emit_label_after (label, insn);
3098 LABEL_NUSES (label) = 0;
3103 /* Return 1 if INSN is a jump that jumps to right after TARGET
3104 only on the condition that TARGET itself would drop through.
3105 Assumes that TARGET is a conditional jump. */
3108 jump_back_p (insn, target)
3112 enum rtx_code codei, codet;
3114 if (simplejump_p (insn) || ! condjump_p (insn)
3115 || simplejump_p (target)
3116 || target != prev_real_insn (JUMP_LABEL (insn)))
3119 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
3120 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
3122 codei = GET_CODE (cinsn);
3123 codet = GET_CODE (ctarget);
3125 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
3127 if (! can_reverse_comparison_p (cinsn, insn))
3129 codei = reverse_condition (codei);
3132 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
3134 if (! can_reverse_comparison_p (ctarget, target))
3136 codet = reverse_condition (codet);
3139 return (codei == codet
3140 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
3141 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
3144 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3145 return non-zero if it is safe to reverse this comparison. It is if our
3146 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3147 this is known to be an integer comparison. */
3150 can_reverse_comparison_p (comparison, insn)
3156 /* If this is not actually a comparison, we can't reverse it. */
3157 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
3160 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3161 /* If this is an NE comparison, it is safe to reverse it to an EQ
3162 comparison and vice versa, even for floating point. If no operands
3163 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3164 always false and NE is always true, so the reversal is also valid. */
3166 || GET_CODE (comparison) == NE
3167 || GET_CODE (comparison) == EQ)
3170 arg0 = XEXP (comparison, 0);
3172 /* Make sure ARG0 is one of the actual objects being compared. If we
3173 can't do this, we can't be sure the comparison can be reversed.
3175 Handle cc0 and a MODE_CC register. */
3176 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
3182 rtx prev = prev_nonnote_insn (insn);
3185 /* If the comparison itself was a loop invariant, it could have been
3186 hoisted out of the loop. If we proceed to unroll such a loop, then
3187 we may not be able to find the comparison when copying the loop.
3189 Returning zero in that case is the safe thing to do. */
3193 set = single_set (prev);
3194 if (set == 0 || SET_DEST (set) != arg0)
3197 arg0 = SET_SRC (set);
3199 if (GET_CODE (arg0) == COMPARE)
3200 arg0 = XEXP (arg0, 0);
3203 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3204 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3205 return (GET_CODE (arg0) == CONST_INT
3206 || (GET_MODE (arg0) != VOIDmode
3207 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
3208 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
3211 /* Given an rtx-code for a comparison, return the code
3212 for the negated comparison.
3213 WATCH OUT! reverse_condition is not safe to use on a jump
3214 that might be acting on the results of an IEEE floating point comparison,
3215 because of the special treatment of non-signaling nans in comparisons.
3216 Use can_reverse_comparison_p to be sure. */
3219 reverse_condition (code)
3260 /* Similar, but return the code when two operands of a comparison are swapped.
3261 This IS safe for IEEE floating-point. */
3264 swap_condition (code)
3303 /* Given a comparison CODE, return the corresponding unsigned comparison.
3304 If CODE is an equality comparison or already an unsigned comparison,
3305 CODE is returned. */
3308 unsigned_condition (code)
3338 /* Similarly, return the signed version of a comparison. */
3341 signed_condition (code)
3371 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3372 truth of CODE1 implies the truth of CODE2. */
3375 comparison_dominates_p (code1, code2)
3376 enum rtx_code code1, code2;
3384 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3389 if (code2 == LE || code2 == NE)
3394 if (code2 == GE || code2 == NE)
3399 if (code2 == LEU || code2 == NE)
3404 if (code2 == GEU || code2 == NE)
3415 /* Return 1 if INSN is an unconditional jump and nothing else. */
3421 return (GET_CODE (insn) == JUMP_INSN
3422 && GET_CODE (PATTERN (insn)) == SET
3423 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3424 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3427 /* Return nonzero if INSN is a (possibly) conditional jump
3428 and nothing more. */
3434 register rtx x = PATTERN (insn);
3435 if (GET_CODE (x) != SET)
3437 if (GET_CODE (SET_DEST (x)) != PC)
3439 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3441 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3443 if (XEXP (SET_SRC (x), 2) == pc_rtx
3444 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3445 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3447 if (XEXP (SET_SRC (x), 1) == pc_rtx
3448 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3449 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3454 /* Return nonzero if INSN is a (possibly) conditional jump
3455 and nothing more. */
3458 condjump_in_parallel_p (insn)
3461 register rtx x = PATTERN (insn);
3463 if (GET_CODE (x) != PARALLEL)
3466 x = XVECEXP (x, 0, 0);
3468 if (GET_CODE (x) != SET)
3470 if (GET_CODE (SET_DEST (x)) != PC)
3472 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3474 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3476 if (XEXP (SET_SRC (x), 2) == pc_rtx
3477 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3478 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3480 if (XEXP (SET_SRC (x), 1) == pc_rtx
3481 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3482 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3487 /* Return the label of a conditional jump. */
3490 condjump_label (insn)
3493 register rtx x = PATTERN (insn);
3495 if (GET_CODE (x) == PARALLEL)
3496 x = XVECEXP (x, 0, 0);
3497 if (GET_CODE (x) != SET)
3499 if (GET_CODE (SET_DEST (x)) != PC)
3502 if (GET_CODE (x) == LABEL_REF)
3504 if (GET_CODE (x) != IF_THEN_ELSE)
3506 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
3508 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
3513 /* Return true if INSN is a (possibly conditional) return insn. */
3516 returnjump_p_1 (loc, data)
3518 void *data ATTRIBUTE_UNUSED;
3521 return GET_CODE (x) == RETURN;
3528 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
3533 /* Return 1 if X is an RTX that does nothing but set the condition codes
3534 and CLOBBER or USE registers.
3535 Return -1 if X does explicitly set the condition codes,
3536 but also does other things. */
3540 rtx x ATTRIBUTE_UNUSED;
3542 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3544 if (GET_CODE (x) == PARALLEL)
3548 int other_things = 0;
3549 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3551 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3552 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3554 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3557 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3563 /* Follow any unconditional jump at LABEL;
3564 return the ultimate label reached by any such chain of jumps.
3565 If LABEL is not followed by a jump, return LABEL.
3566 If the chain loops or we can't find end, return LABEL,
3567 since that tells caller to avoid changing the insn.
3569 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3570 a USE or CLOBBER. */
3573 follow_jumps (label)
3578 register rtx value = label;
3583 && (insn = next_active_insn (value)) != 0
3584 && GET_CODE (insn) == JUMP_INSN
3585 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3586 || GET_CODE (PATTERN (insn)) == RETURN)
3587 && (next = NEXT_INSN (insn))
3588 && GET_CODE (next) == BARRIER);
3591 /* Don't chain through the insn that jumps into a loop
3592 from outside the loop,
3593 since that would create multiple loop entry jumps
3594 and prevent loop optimization. */
3596 if (!reload_completed)
3597 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3598 if (GET_CODE (tem) == NOTE
3599 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3600 /* ??? Optional. Disables some optimizations, but makes
3601 gcov output more accurate with -O. */
3602 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3605 /* If we have found a cycle, make the insn jump to itself. */
3606 if (JUMP_LABEL (insn) == label)
3609 tem = next_active_insn (JUMP_LABEL (insn));
3610 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3611 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3614 value = JUMP_LABEL (insn);
3621 /* Assuming that field IDX of X is a vector of label_refs,
3622 replace each of them by the ultimate label reached by it.
3623 Return nonzero if a change is made.
3624 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3627 tension_vector_labels (x, idx)
3633 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3635 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3636 register rtx nlabel = follow_jumps (olabel);
3637 if (nlabel && nlabel != olabel)
3639 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3640 ++LABEL_NUSES (nlabel);
3641 if (--LABEL_NUSES (olabel) == 0)
3642 delete_insn (olabel);
3649 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3650 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3651 in INSN, then store one of them in JUMP_LABEL (INSN).
3652 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3653 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3654 Also, when there are consecutive labels, canonicalize on the last of them.
3656 Note that two labels separated by a loop-beginning note
3657 must be kept distinct if we have not yet done loop-optimization,
3658 because the gap between them is where loop-optimize
3659 will want to move invariant code to. CROSS_JUMP tells us
3660 that loop-optimization is done with.
3662 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3663 two labels distinct if they are separated by only USE or CLOBBER insns. */
3666 mark_jump_label (x, insn, cross_jump)
3671 register RTX_CODE code = GET_CODE (x);
3689 /* If this is a constant-pool reference, see if it is a label. */
3690 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3691 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3692 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3697 rtx label = XEXP (x, 0);
3702 if (GET_CODE (label) != CODE_LABEL)
3705 /* Ignore references to labels of containing functions. */
3706 if (LABEL_REF_NONLOCAL_P (x))
3709 /* If there are other labels following this one,
3710 replace it with the last of the consecutive labels. */
3711 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3713 if (GET_CODE (next) == CODE_LABEL)
3715 else if (cross_jump && GET_CODE (next) == INSN
3716 && (GET_CODE (PATTERN (next)) == USE
3717 || GET_CODE (PATTERN (next)) == CLOBBER))
3719 else if (GET_CODE (next) != NOTE)
3721 else if (! cross_jump
3722 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3723 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3724 /* ??? Optional. Disables some optimizations, but
3725 makes gcov output more accurate with -O. */
3726 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3730 XEXP (x, 0) = label;
3731 if (! insn || ! INSN_DELETED_P (insn))
3732 ++LABEL_NUSES (label);
3736 if (GET_CODE (insn) == JUMP_INSN)
3737 JUMP_LABEL (insn) = label;
3739 /* If we've changed OLABEL and we had a REG_LABEL note
3740 for it, update it as well. */
3741 else if (label != olabel
3742 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3743 XEXP (note, 0) = label;
3745 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3747 else if (! find_reg_note (insn, REG_LABEL, label))
3749 /* This code used to ignore labels which refered to dispatch
3750 tables to avoid flow.c generating worse code.
3752 However, in the presense of global optimizations like
3753 gcse which call find_basic_blocks without calling
3754 life_analysis, not recording such labels will lead
3755 to compiler aborts because of inconsistencies in the
3756 flow graph. So we go ahead and record the label.
3758 It may also be the case that the optimization argument
3759 is no longer valid because of the more accurate cfg
3760 we build in find_basic_blocks -- it no longer pessimizes
3761 code when it finds a REG_LABEL note. */
3762 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
3769 /* Do walk the labels in a vector, but not the first operand of an
3770 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3773 if (! INSN_DELETED_P (insn))
3775 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3777 for (i = 0; i < XVECLEN (x, eltnum); i++)
3778 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3786 fmt = GET_RTX_FORMAT (code);
3787 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3790 mark_jump_label (XEXP (x, i), insn, cross_jump);
3791 else if (fmt[i] == 'E')
3794 for (j = 0; j < XVECLEN (x, i); j++)
3795 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3800 /* If all INSN does is set the pc, delete it,
3801 and delete the insn that set the condition codes for it
3802 if that's what the previous thing was. */
3808 register rtx set = single_set (insn);
3810 if (set && GET_CODE (SET_DEST (set)) == PC)
3811 delete_computation (insn);
3814 /* Delete INSN and recursively delete insns that compute values used only
3815 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3816 If we are running before flow.c, we need do nothing since flow.c will
3817 delete dead code. We also can't know if the registers being used are
3818 dead or not at this point.
3820 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3821 nothing other than set a register that dies in this insn, we can delete
3824 On machines with CC0, if CC0 is used in this insn, we may be able to
3825 delete the insn that set it. */
3828 delete_computation (insn)
3834 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3836 rtx prev = prev_nonnote_insn (insn);
3837 /* We assume that at this stage
3838 CC's are always set explicitly
3839 and always immediately before the jump that
3840 will use them. So if the previous insn
3841 exists to set the CC's, delete it
3842 (unless it performs auto-increments, etc.). */
3843 if (prev && GET_CODE (prev) == INSN
3844 && sets_cc0_p (PATTERN (prev)))
3846 if (sets_cc0_p (PATTERN (prev)) > 0
3847 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3848 delete_computation (prev);
3850 /* Otherwise, show that cc0 won't be used. */
3851 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
3852 cc0_rtx, REG_NOTES (prev));
3857 #ifdef INSN_SCHEDULING
3858 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
3859 reload has completed. The schedulers need to be fixed. Until
3860 they are, we must not rely on the death notes here. */
3861 if (reload_completed && flag_schedule_insns_after_reload)
3868 for (note = REG_NOTES (insn); note; note = next)
3872 next = XEXP (note, 1);
3874 if (REG_NOTE_KIND (note) != REG_DEAD
3875 /* Verify that the REG_NOTE is legitimate. */
3876 || GET_CODE (XEXP (note, 0)) != REG)
3879 for (our_prev = prev_nonnote_insn (insn);
3880 our_prev && GET_CODE (our_prev) == INSN;
3881 our_prev = prev_nonnote_insn (our_prev))
3883 /* If we reach a SEQUENCE, it is too complex to try to
3884 do anything with it, so give up. */
3885 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3888 if (GET_CODE (PATTERN (our_prev)) == USE
3889 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3890 /* reorg creates USEs that look like this. We leave them
3891 alone because reorg needs them for its own purposes. */
3894 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3896 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3899 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3901 /* If we find a SET of something else, we can't
3906 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3908 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3910 if (GET_CODE (part) == SET
3911 && SET_DEST (part) != XEXP (note, 0))
3915 if (i == XVECLEN (PATTERN (our_prev), 0))
3916 delete_computation (our_prev);
3918 else if (GET_CODE (PATTERN (our_prev)) == SET
3919 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3920 delete_computation (our_prev);
3925 /* If OUR_PREV references the register that dies here, it is an
3926 additional use. Hence any prior SET isn't dead. However, this
3927 insn becomes the new place for the REG_DEAD note. */
3928 if (reg_overlap_mentioned_p (XEXP (note, 0),
3929 PATTERN (our_prev)))
3931 XEXP (note, 1) = REG_NOTES (our_prev);
3932 REG_NOTES (our_prev) = note;
3941 /* Delete insn INSN from the chain of insns and update label ref counts.
3942 May delete some following insns as a consequence; may even delete
3943 a label elsewhere and insns that follow it.
3945 Returns the first insn after INSN that was not deleted. */
3951 register rtx next = NEXT_INSN (insn);
3952 register rtx prev = PREV_INSN (insn);
3953 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3954 register int dont_really_delete = 0;
3956 while (next && INSN_DELETED_P (next))
3957 next = NEXT_INSN (next);
3959 /* This insn is already deleted => return first following nondeleted. */
3960 if (INSN_DELETED_P (insn))
3964 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
3966 /* Don't delete user-declared labels. Convert them to special NOTEs
3968 if (was_code_label && LABEL_NAME (insn) != 0
3969 && optimize && ! dont_really_delete)
3971 PUT_CODE (insn, NOTE);
3972 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3973 NOTE_SOURCE_FILE (insn) = 0;
3974 dont_really_delete = 1;
3977 /* Mark this insn as deleted. */
3978 INSN_DELETED_P (insn) = 1;
3980 /* If this is an unconditional jump, delete it from the jump chain. */
3981 if (simplejump_p (insn))
3982 delete_from_jump_chain (insn);
3984 /* If instruction is followed by a barrier,
3985 delete the barrier too. */
3987 if (next != 0 && GET_CODE (next) == BARRIER)
3989 INSN_DELETED_P (next) = 1;
3990 next = NEXT_INSN (next);
3993 /* Patch out INSN (and the barrier if any) */
3995 if (optimize && ! dont_really_delete)
3999 NEXT_INSN (prev) = next;
4000 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
4001 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
4002 XVECLEN (PATTERN (prev), 0) - 1)) = next;
4007 PREV_INSN (next) = prev;
4008 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
4009 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
4012 if (prev && NEXT_INSN (prev) == 0)
4013 set_last_insn (prev);
4016 /* If deleting a jump, decrement the count of the label,
4017 and delete the label if it is now unused. */
4019 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
4020 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
4022 /* This can delete NEXT or PREV,
4023 either directly if NEXT is JUMP_LABEL (INSN),
4024 or indirectly through more levels of jumps. */
4025 delete_insn (JUMP_LABEL (insn));
4026 /* I feel a little doubtful about this loop,
4027 but I see no clean and sure alternative way
4028 to find the first insn after INSN that is not now deleted.
4029 I hope this works. */
4030 while (next && INSN_DELETED_P (next))
4031 next = NEXT_INSN (next);
4035 /* Likewise if we're deleting a dispatch table. */
4037 if (GET_CODE (insn) == JUMP_INSN
4038 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
4039 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
4041 rtx pat = PATTERN (insn);
4042 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
4043 int len = XVECLEN (pat, diff_vec_p);
4045 for (i = 0; i < len; i++)
4046 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
4047 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
4048 while (next && INSN_DELETED_P (next))
4049 next = NEXT_INSN (next);
4053 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
4054 prev = PREV_INSN (prev);
4056 /* If INSN was a label and a dispatch table follows it,
4057 delete the dispatch table. The tablejump must have gone already.
4058 It isn't useful to fall through into a table. */
4061 && NEXT_INSN (insn) != 0
4062 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
4063 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
4064 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
4065 next = delete_insn (NEXT_INSN (insn));
4067 /* If INSN was a label, delete insns following it if now unreachable. */
4069 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
4071 register RTX_CODE code;
4073 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
4074 || code == NOTE || code == BARRIER
4075 || (code == CODE_LABEL && INSN_DELETED_P (next))))
4078 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
4079 next = NEXT_INSN (next);
4080 /* Keep going past other deleted labels to delete what follows. */
4081 else if (code == CODE_LABEL && INSN_DELETED_P (next))
4082 next = NEXT_INSN (next);
4084 /* Note: if this deletes a jump, it can cause more
4085 deletion of unreachable code, after a different label.
4086 As long as the value from this recursive call is correct,
4087 this invocation functions correctly. */
4088 next = delete_insn (next);
4095 /* Advance from INSN till reaching something not deleted
4096 then return that. May return INSN itself. */
4099 next_nondeleted_insn (insn)
4102 while (INSN_DELETED_P (insn))
4103 insn = NEXT_INSN (insn);
4107 /* Delete a range of insns from FROM to TO, inclusive.
4108 This is for the sake of peephole optimization, so assume
4109 that whatever these insns do will still be done by a new
4110 peephole insn that will replace them. */
4113 delete_for_peephole (from, to)
4114 register rtx from, to;
4116 register rtx insn = from;
4120 register rtx next = NEXT_INSN (insn);
4121 register rtx prev = PREV_INSN (insn);
4123 if (GET_CODE (insn) != NOTE)
4125 INSN_DELETED_P (insn) = 1;
4127 /* Patch this insn out of the chain. */
4128 /* We don't do this all at once, because we
4129 must preserve all NOTEs. */
4131 NEXT_INSN (prev) = next;
4134 PREV_INSN (next) = prev;
4142 /* Note that if TO is an unconditional jump
4143 we *do not* delete the BARRIER that follows,
4144 since the peephole that replaces this sequence
4145 is also an unconditional jump in that case. */
4148 /* Invert the condition of the jump JUMP, and make it jump
4149 to label NLABEL instead of where it jumps now. */
4152 invert_jump (jump, nlabel)
4155 /* We have to either invert the condition and change the label or
4156 do neither. Either operation could fail. We first try to invert
4157 the jump. If that succeeds, we try changing the label. If that fails,
4158 we invert the jump back to what it was. */
4160 if (! invert_exp (PATTERN (jump), jump))
4163 if (redirect_jump (jump, nlabel))
4165 if (flag_branch_probabilities)
4167 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
4169 /* An inverted jump means that a probability taken becomes a
4170 probability not taken. Subtract the branch probability from the
4171 probability base to convert it back to a taken probability.
4172 (We don't flip the probability on a branch that's never taken. */
4173 if (note && XINT (XEXP (note, 0), 0) >= 0)
4174 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
4180 if (! invert_exp (PATTERN (jump), jump))
4181 /* This should just be putting it back the way it was. */
4187 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4189 Return 1 if we can do so, 0 if we cannot find a way to do so that
4190 matches a pattern. */
4193 invert_exp (x, insn)
4197 register RTX_CODE code;
4201 code = GET_CODE (x);
4203 if (code == IF_THEN_ELSE)
4205 register rtx comp = XEXP (x, 0);
4208 /* We can do this in two ways: The preferable way, which can only
4209 be done if this is not an integer comparison, is to reverse
4210 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4211 of the IF_THEN_ELSE. If we can't do either, fail. */
4213 if (can_reverse_comparison_p (comp, insn)
4214 && validate_change (insn, &XEXP (x, 0),
4215 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
4216 GET_MODE (comp), XEXP (comp, 0),
4217 XEXP (comp, 1)), 0))
4221 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
4222 validate_change (insn, &XEXP (x, 2), tem, 1);
4223 return apply_change_group ();
4226 fmt = GET_RTX_FORMAT (code);
4227 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4230 if (! invert_exp (XEXP (x, i), insn))
4235 for (j = 0; j < XVECLEN (x, i); j++)
4236 if (!invert_exp (XVECEXP (x, i, j), insn))
4244 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4245 If the old jump target label is unused as a result,
4246 it and the code following it may be deleted.
4248 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4251 The return value will be 1 if the change was made, 0 if it wasn't (this
4252 can only occur for NLABEL == 0). */
4255 redirect_jump (jump, nlabel)
4258 register rtx olabel = JUMP_LABEL (jump);
4260 if (nlabel == olabel)
4263 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
4266 /* If this is an unconditional branch, delete it from the jump_chain of
4267 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4268 have UID's in range and JUMP_CHAIN is valid). */
4269 if (jump_chain && (simplejump_p (jump)
4270 || GET_CODE (PATTERN (jump)) == RETURN))
4272 int label_index = nlabel ? INSN_UID (nlabel) : 0;
4274 delete_from_jump_chain (jump);
4275 if (label_index < max_jump_chain
4276 && INSN_UID (jump) < max_jump_chain)
4278 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
4279 jump_chain[label_index] = jump;
4283 JUMP_LABEL (jump) = nlabel;
4285 ++LABEL_NUSES (nlabel);
4287 if (olabel && --LABEL_NUSES (olabel) == 0)
4288 delete_insn (olabel);
4293 /* Delete the instruction JUMP from any jump chain it might be on. */
4296 delete_from_jump_chain (jump)
4300 rtx olabel = JUMP_LABEL (jump);
4302 /* Handle unconditional jumps. */
4303 if (jump_chain && olabel != 0
4304 && INSN_UID (olabel) < max_jump_chain
4305 && simplejump_p (jump))
4306 index = INSN_UID (olabel);
4307 /* Handle return insns. */
4308 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
4312 if (jump_chain[index] == jump)
4313 jump_chain[index] = jump_chain[INSN_UID (jump)];
4318 for (insn = jump_chain[index];
4320 insn = jump_chain[INSN_UID (insn)])
4321 if (jump_chain[INSN_UID (insn)] == jump)
4323 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
4329 /* If NLABEL is nonzero, throughout the rtx at LOC,
4330 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4331 zero, alter (RETURN) to (LABEL_REF NLABEL).
4333 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4334 validity with validate_change. Convert (set (pc) (label_ref olabel))
4337 Return 0 if we found a change we would like to make but it is invalid.
4338 Otherwise, return 1. */
4341 redirect_exp (loc, olabel, nlabel, insn)
4346 register rtx x = *loc;
4347 register RTX_CODE code = GET_CODE (x);
4351 if (code == LABEL_REF)
4353 if (XEXP (x, 0) == olabel)
4356 XEXP (x, 0) = nlabel;
4358 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4362 else if (code == RETURN && olabel == 0)
4364 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4365 if (loc == &PATTERN (insn))
4366 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4367 return validate_change (insn, loc, x, 0);
4370 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4371 && GET_CODE (SET_SRC (x)) == LABEL_REF
4372 && XEXP (SET_SRC (x), 0) == olabel)
4373 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4375 fmt = GET_RTX_FORMAT (code);
4376 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4379 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4384 for (j = 0; j < XVECLEN (x, i); j++)
4385 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4393 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4395 If the old jump target label (before the dispatch table) becomes unused,
4396 it and the dispatch table may be deleted. In that case, find the insn
4397 before the jump references that label and delete it and logical successors
4401 redirect_tablejump (jump, nlabel)
4404 register rtx olabel = JUMP_LABEL (jump);
4406 /* Add this jump to the jump_chain of NLABEL. */
4407 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4408 && INSN_UID (jump) < max_jump_chain)
4410 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4411 jump_chain[INSN_UID (nlabel)] = jump;
4414 PATTERN (jump) = gen_jump (nlabel);
4415 JUMP_LABEL (jump) = nlabel;
4416 ++LABEL_NUSES (nlabel);
4417 INSN_CODE (jump) = -1;
4419 if (--LABEL_NUSES (olabel) == 0)
4421 delete_labelref_insn (jump, olabel, 0);
4422 delete_insn (olabel);
4426 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4427 If we found one, delete it and then delete this insn if DELETE_THIS is
4428 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4431 delete_labelref_insn (insn, label, delete_this)
4438 if (GET_CODE (insn) != NOTE
4439 && reg_mentioned_p (label, PATTERN (insn)))
4450 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4451 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4465 /* Like rtx_equal_p except that it considers two REGs as equal
4466 if they renumber to the same value and considers two commutative
4467 operations to be the same if the order of the operands has been
4470 ??? Addition is not commutative on the PA due to the weird implicit
4471 space register selection rules for memory addresses. Therefore, we
4472 don't consider a + b == b + a.
4474 We could/should make this test a little tighter. Possibly only
4475 disabling it on the PA via some backend macro or only disabling this
4476 case when the PLUS is inside a MEM. */
4479 rtx_renumbered_equal_p (x, y)
4483 register RTX_CODE code = GET_CODE (x);
4489 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4490 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4491 && GET_CODE (SUBREG_REG (y)) == REG)))
4493 int reg_x = -1, reg_y = -1;
4494 int word_x = 0, word_y = 0;
4496 if (GET_MODE (x) != GET_MODE (y))
4499 /* If we haven't done any renumbering, don't
4500 make any assumptions. */
4501 if (reg_renumber == 0)
4502 return rtx_equal_p (x, y);
4506 reg_x = REGNO (SUBREG_REG (x));
4507 word_x = SUBREG_WORD (x);
4509 if (reg_renumber[reg_x] >= 0)
4511 reg_x = reg_renumber[reg_x] + word_x;
4519 if (reg_renumber[reg_x] >= 0)
4520 reg_x = reg_renumber[reg_x];
4523 if (GET_CODE (y) == SUBREG)
4525 reg_y = REGNO (SUBREG_REG (y));
4526 word_y = SUBREG_WORD (y);
4528 if (reg_renumber[reg_y] >= 0)
4530 reg_y = reg_renumber[reg_y];
4538 if (reg_renumber[reg_y] >= 0)
4539 reg_y = reg_renumber[reg_y];
4542 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4545 /* Now we have disposed of all the cases
4546 in which different rtx codes can match. */
4547 if (code != GET_CODE (y))
4559 return INTVAL (x) == INTVAL (y);
4562 /* We can't assume nonlocal labels have their following insns yet. */
4563 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4564 return XEXP (x, 0) == XEXP (y, 0);
4566 /* Two label-refs are equivalent if they point at labels
4567 in the same position in the instruction stream. */
4568 return (next_real_insn (XEXP (x, 0))
4569 == next_real_insn (XEXP (y, 0)));
4572 return XSTR (x, 0) == XSTR (y, 0);
4575 /* If we didn't match EQ equality above, they aren't the same. */
4582 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4584 if (GET_MODE (x) != GET_MODE (y))
4587 /* For commutative operations, the RTX match if the operand match in any
4588 order. Also handle the simple binary and unary cases without a loop.
4590 ??? Don't consider PLUS a commutative operator; see comments above. */
4591 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4593 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4594 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4595 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4596 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4597 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4598 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4599 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4600 else if (GET_RTX_CLASS (code) == '1')
4601 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4603 /* Compare the elements. If any pair of corresponding elements
4604 fail to match, return 0 for the whole things. */
4606 fmt = GET_RTX_FORMAT (code);
4607 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4613 if (XWINT (x, i) != XWINT (y, i))
4618 if (XINT (x, i) != XINT (y, i))
4623 if (strcmp (XSTR (x, i), XSTR (y, i)))
4628 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4633 if (XEXP (x, i) != XEXP (y, i))
4640 if (XVECLEN (x, i) != XVECLEN (y, i))
4642 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4643 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4654 /* If X is a hard register or equivalent to one or a subregister of one,
4655 return the hard register number. If X is a pseudo register that was not
4656 assigned a hard register, return the pseudo register number. Otherwise,
4657 return -1. Any rtx is valid for X. */
4663 if (GET_CODE (x) == REG)
4665 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4666 return reg_renumber[REGNO (x)];
4669 if (GET_CODE (x) == SUBREG)
4671 int base = true_regnum (SUBREG_REG (x));
4672 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4673 return SUBREG_WORD (x) + base;
4678 /* Optimize code of the form:
4680 for (x = a[i]; x; ...)
4682 for (x = a[i]; x; ...)
4686 Loop optimize will change the above code into
4690 { ...; if (! (x = ...)) break; }
4693 { ...; if (! (x = ...)) break; }
4696 In general, if the first test fails, the program can branch
4697 directly to `foo' and skip the second try which is doomed to fail.
4698 We run this after loop optimization and before flow analysis. */
4700 /* When comparing the insn patterns, we track the fact that different
4701 pseudo-register numbers may have been used in each computation.
4702 The following array stores an equivalence -- same_regs[I] == J means
4703 that pseudo register I was used in the first set of tests in a context
4704 where J was used in the second set. We also count the number of such
4705 pending equivalences. If nonzero, the expressions really aren't the
4708 static int *same_regs;
4710 static int num_same_regs;
4712 /* Track any registers modified between the target of the first jump and
4713 the second jump. They never compare equal. */
4715 static char *modified_regs;
4717 /* Record if memory was modified. */
4719 static int modified_mem;
4721 /* Called via note_stores on each insn between the target of the first
4722 branch and the second branch. It marks any changed registers. */
4725 mark_modified_reg (dest, x)
4727 rtx x ATTRIBUTE_UNUSED;
4731 if (GET_CODE (dest) == SUBREG)
4732 dest = SUBREG_REG (dest);
4734 if (GET_CODE (dest) == MEM)
4737 if (GET_CODE (dest) != REG)
4740 regno = REGNO (dest);
4741 if (regno >= FIRST_PSEUDO_REGISTER)
4742 modified_regs[regno] = 1;
4744 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4745 modified_regs[regno + i] = 1;
4748 /* F is the first insn in the chain of insns. */
4751 thread_jumps (f, max_reg, flag_before_loop)
4754 int flag_before_loop;
4756 /* Basic algorithm is to find a conditional branch,
4757 the label it may branch to, and the branch after
4758 that label. If the two branches test the same condition,
4759 walk back from both branch paths until the insn patterns
4760 differ, or code labels are hit. If we make it back to
4761 the target of the first branch, then we know that the first branch
4762 will either always succeed or always fail depending on the relative
4763 senses of the two branches. So adjust the first branch accordingly
4766 rtx label, b1, b2, t1, t2;
4767 enum rtx_code code1, code2;
4768 rtx b1op0, b1op1, b2op0, b2op1;
4773 /* Allocate register tables and quick-reset table. */
4774 modified_regs = (char *) alloca (max_reg * sizeof (char));
4775 same_regs = (int *) alloca (max_reg * sizeof (int));
4776 all_reset = (int *) alloca (max_reg * sizeof (int));
4777 for (i = 0; i < max_reg; i++)
4784 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4786 /* Get to a candidate branch insn. */
4787 if (GET_CODE (b1) != JUMP_INSN
4788 || ! condjump_p (b1) || simplejump_p (b1)
4789 || JUMP_LABEL (b1) == 0)
4792 bzero (modified_regs, max_reg * sizeof (char));
4795 bcopy ((char *) all_reset, (char *) same_regs,
4796 max_reg * sizeof (int));
4799 label = JUMP_LABEL (b1);
4801 /* Look for a branch after the target. Record any registers and
4802 memory modified between the target and the branch. Stop when we
4803 get to a label since we can't know what was changed there. */
4804 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4806 if (GET_CODE (b2) == CODE_LABEL)
4809 else if (GET_CODE (b2) == JUMP_INSN)
4811 /* If this is an unconditional jump and is the only use of
4812 its target label, we can follow it. */
4813 if (simplejump_p (b2)
4814 && JUMP_LABEL (b2) != 0
4815 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4817 b2 = JUMP_LABEL (b2);
4824 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4827 if (GET_CODE (b2) == CALL_INSN)
4830 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4831 if (call_used_regs[i] && ! fixed_regs[i]
4832 && i != STACK_POINTER_REGNUM
4833 && i != FRAME_POINTER_REGNUM
4834 && i != HARD_FRAME_POINTER_REGNUM
4835 && i != ARG_POINTER_REGNUM)
4836 modified_regs[i] = 1;
4839 note_stores (PATTERN (b2), mark_modified_reg);
4842 /* Check the next candidate branch insn from the label
4845 || GET_CODE (b2) != JUMP_INSN
4847 || ! condjump_p (b2)
4848 || simplejump_p (b2))
4851 /* Get the comparison codes and operands, reversing the
4852 codes if appropriate. If we don't have comparison codes,
4853 we can't do anything. */
4854 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4855 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4856 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4857 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4858 code1 = reverse_condition (code1);
4860 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4861 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4862 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4863 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4864 code2 = reverse_condition (code2);
4866 /* If they test the same things and knowing that B1 branches
4867 tells us whether or not B2 branches, check if we
4868 can thread the branch. */
4869 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4870 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4871 && (comparison_dominates_p (code1, code2)
4872 || (comparison_dominates_p (code1, reverse_condition (code2))
4873 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
4877 t1 = prev_nonnote_insn (b1);
4878 t2 = prev_nonnote_insn (b2);
4880 while (t1 != 0 && t2 != 0)
4884 /* We have reached the target of the first branch.
4885 If there are no pending register equivalents,
4886 we know that this branch will either always
4887 succeed (if the senses of the two branches are
4888 the same) or always fail (if not). */
4891 if (num_same_regs != 0)
4894 if (comparison_dominates_p (code1, code2))
4895 new_label = JUMP_LABEL (b2);
4897 new_label = get_label_after (b2);
4899 if (JUMP_LABEL (b1) != new_label)
4901 rtx prev = PREV_INSN (new_label);
4903 if (flag_before_loop
4904 && GET_CODE (prev) == NOTE
4905 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4907 /* Don't thread to the loop label. If a loop
4908 label is reused, loop optimization will
4909 be disabled for that loop. */
4910 new_label = gen_label_rtx ();
4911 emit_label_after (new_label, PREV_INSN (prev));
4913 changed |= redirect_jump (b1, new_label);
4918 /* If either of these is not a normal insn (it might be
4919 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4920 have already been skipped above.) Similarly, fail
4921 if the insns are different. */
4922 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4923 || recog_memoized (t1) != recog_memoized (t2)
4924 || ! rtx_equal_for_thread_p (PATTERN (t1),
4928 t1 = prev_nonnote_insn (t1);
4929 t2 = prev_nonnote_insn (t2);
4936 /* This is like RTX_EQUAL_P except that it knows about our handling of
4937 possibly equivalent registers and knows to consider volatile and
4938 modified objects as not equal.
4940 YINSN is the insn containing Y. */
4943 rtx_equal_for_thread_p (x, y, yinsn)
4949 register enum rtx_code code;
4952 code = GET_CODE (x);
4953 /* Rtx's of different codes cannot be equal. */
4954 if (code != GET_CODE (y))
4957 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4958 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4960 if (GET_MODE (x) != GET_MODE (y))
4963 /* For floating-point, consider everything unequal. This is a bit
4964 pessimistic, but this pass would only rarely do anything for FP
4966 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4967 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
4970 /* For commutative operations, the RTX match if the operand match in any
4971 order. Also handle the simple binary and unary cases without a loop. */
4972 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4973 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4974 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4975 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4976 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4977 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4978 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4979 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4980 else if (GET_RTX_CLASS (code) == '1')
4981 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4983 /* Handle special-cases first. */
4987 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4990 /* If neither is user variable or hard register, check for possible
4992 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4993 || REGNO (x) < FIRST_PSEUDO_REGISTER
4994 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4997 if (same_regs[REGNO (x)] == -1)
4999 same_regs[REGNO (x)] = REGNO (y);
5002 /* If this is the first time we are seeing a register on the `Y'
5003 side, see if it is the last use. If not, we can't thread the
5004 jump, so mark it as not equivalent. */
5005 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
5011 return (same_regs[REGNO (x)] == REGNO (y));
5016 /* If memory modified or either volatile, not equivalent.
5017 Else, check address. */
5018 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5021 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
5024 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5030 /* Cancel a pending `same_regs' if setting equivalenced registers.
5031 Then process source. */
5032 if (GET_CODE (SET_DEST (x)) == REG
5033 && GET_CODE (SET_DEST (y)) == REG)
5035 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
5037 same_regs[REGNO (SET_DEST (x))] = -1;
5040 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
5044 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
5047 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
5050 return XEXP (x, 0) == XEXP (y, 0);
5053 return XSTR (x, 0) == XSTR (y, 0);
5062 fmt = GET_RTX_FORMAT (code);
5063 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5068 if (XWINT (x, i) != XWINT (y, i))
5074 if (XINT (x, i) != XINT (y, i))
5080 /* Two vectors must have the same length. */
5081 if (XVECLEN (x, i) != XVECLEN (y, i))
5084 /* And the corresponding elements must match. */
5085 for (j = 0; j < XVECLEN (x, i); j++)
5086 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
5087 XVECEXP (y, i, j), yinsn) == 0)
5092 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
5098 if (strcmp (XSTR (x, i), XSTR (y, i)))
5103 /* These are just backpointers, so they don't matter. */
5109 /* It is believed that rtx's at this level will never
5110 contain anything but integers and other rtx's,
5111 except for within LABEL_REFs and SYMBOL_REFs. */
5121 /* Return the insn that NEW can be safely inserted in front of starting at
5122 the jump insn INSN. Return 0 if it is not safe to do this jump
5123 optimization. Note that NEW must contain a single set. */
5126 find_insert_position (insn, new)
5133 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
5134 if (GET_CODE (PATTERN (new)) != PARALLEL)
5137 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5138 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5139 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5146 /* There is a good chance that the previous insn PREV sets the thing
5147 being clobbered (often the CC in a hard reg). If PREV does not
5148 use what NEW sets, we can insert NEW before PREV. */
5150 prev = prev_active_insn (insn);
5151 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5152 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5153 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5155 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5159 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
5161 #endif /* !HAVE_cc0 */