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. */
59 #include "hard-reg-set.h"
61 #include "insn-config.h"
62 #include "insn-flags.h"
63 #include "insn-attr.h"
71 /* ??? Eventually must record somehow the labels used by jumps
72 from nested functions. */
73 /* Pre-record the next or previous real insn for each label?
74 No, this pass is very fast anyway. */
75 /* Condense consecutive labels?
76 This would make life analysis faster, maybe. */
77 /* Optimize jump y; x: ... y: jumpif... x?
78 Don't know if it is worth bothering with. */
79 /* Optimize two cases of conditional jump to conditional jump?
80 This can never delete any instruction or make anything dead,
81 or even change what is live at any point.
82 So perhaps let combiner do it. */
84 /* Vector indexed by uid.
85 For each CODE_LABEL, index by its uid to get first unconditional jump
86 that jumps to the label.
87 For each JUMP_INSN, index by its uid to get the next unconditional jump
88 that jumps to the same label.
89 Element 0 is the start of a chain of all return insns.
90 (It is safe to use element 0 because insn uid 0 is not used. */
92 static rtx *jump_chain;
94 /* Maximum index in jump_chain. */
96 static int max_jump_chain;
98 /* Set nonzero by jump_optimize if control can fall through
99 to the end of the function. */
102 /* Indicates whether death notes are significant in cross jump analysis.
103 Normally they are not significant, because of A and B jump to C,
104 and R dies in A, it must die in B. But this might not be true after
105 stack register conversion, and we must compare death notes in that
108 static int cross_jump_death_matters = 0;
110 static int init_label_info PROTO((rtx));
111 static void delete_barrier_successors PROTO((rtx));
112 static void mark_all_labels PROTO((rtx, int));
113 static rtx delete_unreferenced_labels PROTO((rtx));
114 static void delete_noop_moves PROTO((rtx));
115 static int calculate_can_reach_end PROTO((rtx, int, int));
116 static int duplicate_loop_exit_test PROTO((rtx));
117 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
118 static void do_cross_jump PROTO((rtx, rtx, rtx));
119 static int jump_back_p PROTO((rtx, rtx));
120 static int tension_vector_labels PROTO((rtx, int));
121 static void mark_jump_label PROTO((rtx, rtx, int));
122 static void delete_computation PROTO((rtx));
123 static void delete_from_jump_chain PROTO((rtx));
124 static int delete_labelref_insn PROTO((rtx, rtx, int));
125 static void mark_modified_reg PROTO((rtx, rtx));
126 static void redirect_tablejump PROTO((rtx, rtx));
127 static void jump_optimize_1 PROTO ((rtx, int, int, int, int));
128 #if ! defined(HAVE_cc0) && ! defined(HAVE_conditional_arithmetic)
129 static rtx find_insert_position PROTO((rtx, rtx));
131 static int returnjump_p_1 PROTO((rtx *, void *));
132 static void delete_prior_computation 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)
297 /* An ADDRESSOF expression can turn into a use of the internal arg
298 pointer, so do not delete the initialization of the internal
299 arg pointer yet. If it is truly dead, flow will delete the
300 initializing insn. */
301 && SET_DEST (set) != current_function_internal_arg_pointer)
305 /* Now iterate optimizing jumps until nothing changes over one pass. */
307 old_max_reg = max_reg_num ();
312 for (insn = f; insn; insn = next)
315 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
317 int this_is_simplejump, this_is_condjump, reversep = 0;
318 int this_is_condjump_in_parallel;
320 next = NEXT_INSN (insn);
322 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
323 jump. Try to optimize by duplicating the loop exit test if so.
324 This is only safe immediately after regscan, because it uses
325 the values of regno_first_uid and regno_last_uid. */
326 if (after_regscan && GET_CODE (insn) == NOTE
327 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
328 && (temp1 = next_nonnote_insn (insn)) != 0
329 && simplejump_p (temp1))
331 temp = PREV_INSN (insn);
332 if (duplicate_loop_exit_test (insn))
335 next = NEXT_INSN (temp);
340 if (GET_CODE (insn) != JUMP_INSN)
343 this_is_simplejump = simplejump_p (insn);
344 this_is_condjump = condjump_p (insn);
345 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
347 /* Tension the labels in dispatch tables. */
349 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
350 changed |= tension_vector_labels (PATTERN (insn), 0);
351 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
352 changed |= tension_vector_labels (PATTERN (insn), 1);
354 /* See if this jump goes to another jump and redirect if so. */
355 nlabel = follow_jumps (JUMP_LABEL (insn));
356 if (nlabel != JUMP_LABEL (insn))
357 changed |= redirect_jump (insn, nlabel);
359 /* If a dispatch table always goes to the same place,
360 get rid of it and replace the insn that uses it. */
362 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
363 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
366 rtx pat = PATTERN (insn);
367 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
368 int len = XVECLEN (pat, diff_vec_p);
369 rtx dispatch = prev_real_insn (insn);
371 for (i = 0; i < len; i++)
372 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
373 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
377 && GET_CODE (dispatch) == JUMP_INSN
378 && JUMP_LABEL (dispatch) != 0
379 /* Don't mess with a casesi insn. */
380 && !(GET_CODE (PATTERN (dispatch)) == SET
381 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
383 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
385 redirect_tablejump (dispatch,
386 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
391 /* If a jump references the end of the function, try to turn
392 it into a RETURN insn, possibly a conditional one. */
393 if (JUMP_LABEL (insn) != 0
394 && (next_active_insn (JUMP_LABEL (insn)) == 0
395 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
397 changed |= redirect_jump (insn, NULL_RTX);
399 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
401 /* Detect jump to following insn. */
402 if (reallabelprev == insn && this_is_condjump)
404 next = next_real_insn (JUMP_LABEL (insn));
410 /* Detect a conditional jump going to the same place
411 as an immediately following unconditional jump. */
412 else if (this_is_condjump
413 && (temp = next_active_insn (insn)) != 0
414 && simplejump_p (temp)
415 && (next_active_insn (JUMP_LABEL (insn))
416 == next_active_insn (JUMP_LABEL (temp))))
418 /* Don't mess up test coverage analysis. */
420 if (flag_test_coverage && !reload_completed)
421 for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
422 if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
433 /* Detect a conditional jump jumping over an unconditional jump. */
435 else if ((this_is_condjump || this_is_condjump_in_parallel)
436 && ! this_is_simplejump
437 && reallabelprev != 0
438 && GET_CODE (reallabelprev) == JUMP_INSN
439 && prev_active_insn (reallabelprev) == insn
440 && no_labels_between_p (insn, reallabelprev)
441 && simplejump_p (reallabelprev))
443 /* When we invert the unconditional jump, we will be
444 decrementing the usage count of its old label.
445 Make sure that we don't delete it now because that
446 might cause the following code to be deleted. */
447 rtx prev_uses = prev_nonnote_insn (reallabelprev);
448 rtx prev_label = JUMP_LABEL (insn);
451 ++LABEL_NUSES (prev_label);
453 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
455 /* It is very likely that if there are USE insns before
456 this jump, they hold REG_DEAD notes. These REG_DEAD
457 notes are no longer valid due to this optimization,
458 and will cause the life-analysis that following passes
459 (notably delayed-branch scheduling) to think that
460 these registers are dead when they are not.
462 To prevent this trouble, we just remove the USE insns
463 from the insn chain. */
465 while (prev_uses && GET_CODE (prev_uses) == INSN
466 && GET_CODE (PATTERN (prev_uses)) == USE)
468 rtx useless = prev_uses;
469 prev_uses = prev_nonnote_insn (prev_uses);
470 delete_insn (useless);
473 delete_insn (reallabelprev);
477 /* We can now safely delete the label if it is unreferenced
478 since the delete_insn above has deleted the BARRIER. */
479 if (prev_label && --LABEL_NUSES (prev_label) == 0)
480 delete_insn (prev_label);
482 next = NEXT_INSN (insn);
485 /* If we have an unconditional jump preceded by a USE, try to put
486 the USE before the target and jump there. This simplifies many
487 of the optimizations below since we don't have to worry about
488 dealing with these USE insns. We only do this if the label
489 being branch to already has the identical USE or if code
490 never falls through to that label. */
492 else if (this_is_simplejump
493 && (temp = prev_nonnote_insn (insn)) != 0
494 && GET_CODE (temp) == INSN
495 && GET_CODE (PATTERN (temp)) == USE
496 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
497 && (GET_CODE (temp1) == BARRIER
498 || (GET_CODE (temp1) == INSN
499 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
500 /* Don't do this optimization if we have a loop containing
501 only the USE instruction, and the loop start label has
502 a usage count of 1. This is because we will redo this
503 optimization everytime through the outer loop, and jump
504 opt will never exit. */
505 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
506 && temp2 == JUMP_LABEL (insn)
507 && LABEL_NUSES (temp2) == 1))
509 if (GET_CODE (temp1) == BARRIER)
511 emit_insn_after (PATTERN (temp), temp1);
512 temp1 = NEXT_INSN (temp1);
516 redirect_jump (insn, get_label_before (temp1));
517 reallabelprev = prev_real_insn (temp1);
519 next = NEXT_INSN (insn);
522 /* Simplify if (...) x = a; else x = b; by converting it
523 to x = b; if (...) x = a;
524 if B is sufficiently simple, the test doesn't involve X,
525 and nothing in the test modifies B or X.
527 If we have small register classes, we also can't do this if X
530 If the "x = b;" insn has any REG_NOTES, we don't do this because
531 of the possibility that we are running after CSE and there is a
532 REG_EQUAL note that is only valid if the branch has already been
533 taken. If we move the insn with the REG_EQUAL note, we may
534 fold the comparison to always be false in a later CSE pass.
535 (We could also delete the REG_NOTES when moving the insn, but it
536 seems simpler to not move it.) An exception is that we can move
537 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
538 value is the same as "b".
540 INSN is the branch over the `else' part.
544 TEMP to the jump insn preceding "x = a;"
546 TEMP2 to the insn that sets "x = b;"
547 TEMP3 to the insn that sets "x = a;"
548 TEMP4 to the set of "x = b"; */
550 if (this_is_simplejump
551 && (temp3 = prev_active_insn (insn)) != 0
552 && GET_CODE (temp3) == INSN
553 && (temp4 = single_set (temp3)) != 0
554 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
555 && (! SMALL_REGISTER_CLASSES
556 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
557 && (temp2 = next_active_insn (insn)) != 0
558 && GET_CODE (temp2) == INSN
559 && (temp4 = single_set (temp2)) != 0
560 && rtx_equal_p (SET_DEST (temp4), temp1)
561 && ! side_effects_p (SET_SRC (temp4))
562 && ! may_trap_p (SET_SRC (temp4))
563 && (REG_NOTES (temp2) == 0
564 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
565 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
566 && XEXP (REG_NOTES (temp2), 1) == 0
567 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
569 && (temp = prev_active_insn (temp3)) != 0
570 && condjump_p (temp) && ! simplejump_p (temp)
571 /* TEMP must skip over the "x = a;" insn */
572 && prev_real_insn (JUMP_LABEL (temp)) == insn
573 && no_labels_between_p (insn, JUMP_LABEL (temp))
574 /* There must be no other entries to the "x = b;" insn. */
575 && no_labels_between_p (JUMP_LABEL (temp), temp2)
576 /* INSN must either branch to the insn after TEMP2 or the insn
577 after TEMP2 must branch to the same place as INSN. */
578 && (reallabelprev == temp2
579 || ((temp5 = next_active_insn (temp2)) != 0
580 && simplejump_p (temp5)
581 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
583 /* The test expression, X, may be a complicated test with
584 multiple branches. See if we can find all the uses of
585 the label that TEMP branches to without hitting a CALL_INSN
586 or a jump to somewhere else. */
587 rtx target = JUMP_LABEL (temp);
588 int nuses = LABEL_NUSES (target);
594 /* Set P to the first jump insn that goes around "x = a;". */
595 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
597 if (GET_CODE (p) == JUMP_INSN)
599 if (condjump_p (p) && ! simplejump_p (p)
600 && JUMP_LABEL (p) == target)
609 else if (GET_CODE (p) == CALL_INSN)
614 /* We cannot insert anything between a set of cc and its use
615 so if P uses cc0, we must back up to the previous insn. */
616 q = prev_nonnote_insn (p);
617 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
618 && sets_cc0_p (PATTERN (q)))
625 /* If we found all the uses and there was no data conflict, we
626 can move the assignment unless we can branch into the middle
629 && no_labels_between_p (p, insn)
630 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
631 && ! reg_set_between_p (temp1, p, temp3)
632 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
633 || ! modified_between_p (SET_SRC (temp4), p, temp2))
634 /* Verify that registers used by the jump are not clobbered
635 by the instruction being moved. */
636 && ! regs_set_between_p (PATTERN (temp),
640 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
643 /* Set NEXT to an insn that we know won't go away. */
644 next = next_active_insn (insn);
646 /* Delete the jump around the set. Note that we must do
647 this before we redirect the test jumps so that it won't
648 delete the code immediately following the assignment
649 we moved (which might be a jump). */
653 /* We either have two consecutive labels or a jump to
654 a jump, so adjust all the JUMP_INSNs to branch to where
656 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
657 if (GET_CODE (p) == JUMP_INSN)
658 redirect_jump (p, target);
661 next = NEXT_INSN (insn);
666 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
667 to x = a; if (...) goto l; x = b;
668 if A is sufficiently simple, the test doesn't involve X,
669 and nothing in the test modifies A or X.
671 If we have small register classes, we also can't do this if X
674 If the "x = a;" insn has any REG_NOTES, we don't do this because
675 of the possibility that we are running after CSE and there is a
676 REG_EQUAL note that is only valid if the branch has already been
677 taken. If we move the insn with the REG_EQUAL note, we may
678 fold the comparison to always be false in a later CSE pass.
679 (We could also delete the REG_NOTES when moving the insn, but it
680 seems simpler to not move it.) An exception is that we can move
681 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
682 value is the same as "a".
688 TEMP to the jump insn preceding "x = a;"
690 TEMP2 to the insn that sets "x = b;"
691 TEMP3 to the insn that sets "x = a;"
692 TEMP4 to the set of "x = a"; */
694 if (this_is_simplejump
695 && (temp2 = next_active_insn (insn)) != 0
696 && GET_CODE (temp2) == INSN
697 && (temp4 = single_set (temp2)) != 0
698 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
699 && (! SMALL_REGISTER_CLASSES
700 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
701 && (temp3 = prev_active_insn (insn)) != 0
702 && GET_CODE (temp3) == INSN
703 && (temp4 = single_set (temp3)) != 0
704 && rtx_equal_p (SET_DEST (temp4), temp1)
705 && ! side_effects_p (SET_SRC (temp4))
706 && ! may_trap_p (SET_SRC (temp4))
707 && (REG_NOTES (temp3) == 0
708 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
709 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
710 && XEXP (REG_NOTES (temp3), 1) == 0
711 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
713 && (temp = prev_active_insn (temp3)) != 0
714 && condjump_p (temp) && ! simplejump_p (temp)
715 /* TEMP must skip over the "x = a;" insn */
716 && prev_real_insn (JUMP_LABEL (temp)) == insn
717 && no_labels_between_p (temp, insn))
719 rtx prev_label = JUMP_LABEL (temp);
720 rtx insert_after = prev_nonnote_insn (temp);
723 /* We cannot insert anything between a set of cc and its use. */
724 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
725 && sets_cc0_p (PATTERN (insert_after)))
726 insert_after = prev_nonnote_insn (insert_after);
728 ++LABEL_NUSES (prev_label);
731 && no_labels_between_p (insert_after, temp)
732 && ! reg_referenced_between_p (temp1, insert_after, temp3)
733 && ! reg_referenced_between_p (temp1, temp3,
735 && ! reg_set_between_p (temp1, insert_after, temp)
736 && ! modified_between_p (SET_SRC (temp4), insert_after, temp)
737 /* Verify that registers used by the jump are not clobbered
738 by the instruction being moved. */
739 && ! regs_set_between_p (PATTERN (temp),
742 && invert_jump (temp, JUMP_LABEL (insn)))
744 emit_insn_after_with_line_notes (PATTERN (temp3),
745 insert_after, temp3);
748 /* Set NEXT to an insn that we know won't go away. */
752 if (prev_label && --LABEL_NUSES (prev_label) == 0)
753 delete_insn (prev_label);
758 #if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
760 /* If we have if (...) x = exp; and branches are expensive,
761 EXP is a single insn, does not have any side effects, cannot
762 trap, and is not too costly, convert this to
763 t = exp; if (...) x = t;
765 Don't do this when we have CC0 because it is unlikely to help
766 and we'd need to worry about where to place the new insn and
767 the potential for conflicts. We also can't do this when we have
768 notes on the insn for the same reason as above.
770 If we have conditional arithmetic, this will make this
771 harder to optimize later and isn't needed, so don't do it
776 TEMP to the "x = exp;" insn.
777 TEMP1 to the single set in the "x = exp;" insn.
780 if (! reload_completed
781 && this_is_condjump && ! this_is_simplejump
783 && (temp = next_nonnote_insn (insn)) != 0
784 && GET_CODE (temp) == INSN
785 && REG_NOTES (temp) == 0
786 && (reallabelprev == temp
787 || ((temp2 = next_active_insn (temp)) != 0
788 && simplejump_p (temp2)
789 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
790 && (temp1 = single_set (temp)) != 0
791 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
792 && (! SMALL_REGISTER_CLASSES
793 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
794 && GET_CODE (SET_SRC (temp1)) != REG
795 && GET_CODE (SET_SRC (temp1)) != SUBREG
796 && GET_CODE (SET_SRC (temp1)) != CONST_INT
797 && ! side_effects_p (SET_SRC (temp1))
798 && ! may_trap_p (SET_SRC (temp1))
799 && rtx_cost (SET_SRC (temp1), SET) < 10)
801 rtx new = gen_reg_rtx (GET_MODE (temp2));
803 if ((temp3 = find_insert_position (insn, temp))
804 && validate_change (temp, &SET_DEST (temp1), new, 0))
806 next = emit_insn_after (gen_move_insn (temp2, new), insn);
807 emit_insn_after_with_line_notes (PATTERN (temp),
808 PREV_INSN (temp3), temp);
810 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
814 reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
815 old_max_reg = max_reg_num ();
820 /* Similarly, if it takes two insns to compute EXP but they
821 have the same destination. Here TEMP3 will be the second
822 insn and TEMP4 the SET from that insn. */
824 if (! reload_completed
825 && this_is_condjump && ! this_is_simplejump
827 && (temp = next_nonnote_insn (insn)) != 0
828 && GET_CODE (temp) == INSN
829 && REG_NOTES (temp) == 0
830 && (temp3 = next_nonnote_insn (temp)) != 0
831 && GET_CODE (temp3) == INSN
832 && REG_NOTES (temp3) == 0
833 && (reallabelprev == temp3
834 || ((temp2 = next_active_insn (temp3)) != 0
835 && simplejump_p (temp2)
836 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
837 && (temp1 = single_set (temp)) != 0
838 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
839 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
840 && (! SMALL_REGISTER_CLASSES
841 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
842 && ! side_effects_p (SET_SRC (temp1))
843 && ! may_trap_p (SET_SRC (temp1))
844 && rtx_cost (SET_SRC (temp1), SET) < 10
845 && (temp4 = single_set (temp3)) != 0
846 && rtx_equal_p (SET_DEST (temp4), temp2)
847 && ! side_effects_p (SET_SRC (temp4))
848 && ! may_trap_p (SET_SRC (temp4))
849 && rtx_cost (SET_SRC (temp4), SET) < 10)
851 rtx new = gen_reg_rtx (GET_MODE (temp2));
853 if ((temp5 = find_insert_position (insn, temp))
854 && (temp6 = find_insert_position (insn, temp3))
855 && validate_change (temp, &SET_DEST (temp1), new, 0))
857 /* Use the earliest of temp5 and temp6. */
860 next = emit_insn_after (gen_move_insn (temp2, new), insn);
861 emit_insn_after_with_line_notes (PATTERN (temp),
862 PREV_INSN (temp6), temp);
863 emit_insn_after_with_line_notes
864 (replace_rtx (PATTERN (temp3), temp2, new),
865 PREV_INSN (temp6), temp3);
868 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
872 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
873 old_max_reg = max_reg_num ();
878 /* Finally, handle the case where two insns are used to
879 compute EXP but a temporary register is used. Here we must
880 ensure that the temporary register is not used anywhere else. */
882 if (! reload_completed
884 && this_is_condjump && ! this_is_simplejump
886 && (temp = next_nonnote_insn (insn)) != 0
887 && GET_CODE (temp) == INSN
888 && REG_NOTES (temp) == 0
889 && (temp3 = next_nonnote_insn (temp)) != 0
890 && GET_CODE (temp3) == INSN
891 && REG_NOTES (temp3) == 0
892 && (reallabelprev == temp3
893 || ((temp2 = next_active_insn (temp3)) != 0
894 && simplejump_p (temp2)
895 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
896 && (temp1 = single_set (temp)) != 0
897 && (temp5 = SET_DEST (temp1),
898 (GET_CODE (temp5) == REG
899 || (GET_CODE (temp5) == SUBREG
900 && (temp5 = SUBREG_REG (temp5),
901 GET_CODE (temp5) == REG))))
902 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
903 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
904 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
905 && ! side_effects_p (SET_SRC (temp1))
906 && ! may_trap_p (SET_SRC (temp1))
907 && rtx_cost (SET_SRC (temp1), SET) < 10
908 && (temp4 = single_set (temp3)) != 0
909 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
910 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
911 && (! SMALL_REGISTER_CLASSES
912 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
913 && rtx_equal_p (SET_DEST (temp4), temp2)
914 && ! side_effects_p (SET_SRC (temp4))
915 && ! may_trap_p (SET_SRC (temp4))
916 && rtx_cost (SET_SRC (temp4), SET) < 10)
918 rtx new = gen_reg_rtx (GET_MODE (temp2));
920 if ((temp5 = find_insert_position (insn, temp))
921 && (temp6 = find_insert_position (insn, temp3))
922 && validate_change (temp3, &SET_DEST (temp4), new, 0))
924 /* Use the earliest of temp5 and temp6. */
927 next = emit_insn_after (gen_move_insn (temp2, new), insn);
928 emit_insn_after_with_line_notes (PATTERN (temp),
929 PREV_INSN (temp6), temp);
930 emit_insn_after_with_line_notes (PATTERN (temp3),
931 PREV_INSN (temp6), temp3);
934 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
938 reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
939 old_max_reg = max_reg_num ();
943 #endif /* HAVE_cc0 */
945 #ifdef HAVE_conditional_arithmetic
946 /* ??? This is disabled in genconfig, as this simple-minded
947 transformation can incredibly lengthen register lifetimes.
949 Consider this example from cexp.c's yyparse:
952 (if_then_else (ne (reg:DI 149) (const_int 0 [0x0]))
953 (label_ref 248) (pc)))
954 237 (set (reg/i:DI 0 $0) (const_int 1 [0x1]))
955 239 (set (pc) (label_ref 2382))
956 248 (code_label ("yybackup"))
958 This will be transformed to:
960 237 (set (reg/i:DI 0 $0)
961 (if_then_else:DI (eq (reg:DI 149) (const_int 0 [0x0]))
962 (const_int 1 [0x1]) (reg/i:DI 0 $0)))
964 (if_then_else (eq (reg:DI 149) (const_int 0 [0x0]))
965 (label_ref 2382) (pc)))
967 which, from this narrow viewpoint looks fine. Except that
968 between this and 3 other ocurrences of the same pattern, $0
969 is now live for basically the entire function, and we'll
970 get an abort in caller_save.
972 Any replacement for this code should recall that a set of
973 a register that is not live need not, and indeed should not,
974 be conditionalized. Either that, or delay the transformation
975 until after register allocation. */
977 /* See if this is a conditional jump around a small number of
978 instructions that we can conditionalize. Don't do this before
979 the initial CSE pass or after reload.
981 We reject any insns that have side effects or may trap.
982 Strictly speaking, this is not needed since the machine may
983 support conditionalizing these too, but we won't deal with that
984 now. Specifically, this means that we can't conditionalize a
985 CALL_INSN, which some machines, such as the ARC, can do, but
986 this is a very minor optimization. */
987 if (this_is_condjump && ! this_is_simplejump
988 && cse_not_expected && optimize > 0 && ! reload_completed
990 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (insn)), 0),
993 rtx ourcond = XEXP (SET_SRC (PATTERN (insn)), 0);
995 char *storage = (char *) oballoc (0);
996 int last_insn = 0, failed = 0;
997 rtx changed_jump = 0;
999 ourcond = gen_rtx (reverse_condition (GET_CODE (ourcond)),
1000 VOIDmode, XEXP (ourcond, 0),
1003 /* Scan forward BRANCH_COST real insns looking for the JUMP_LABEL
1004 of this insn. We see if we think we can conditionalize the
1005 insns we pass. For now, we only deal with insns that have
1006 one SET. We stop after an insn that modifies anything in
1007 OURCOND, if we have too many insns, or if we have an insn
1008 with a side effect or that may trip. Note that we will
1009 be modifying any unconditional jumps we encounter to be
1010 conditional; this will have the effect of also doing this
1011 optimization on the "else" the next time around. */
1012 for (temp1 = NEXT_INSN (insn);
1013 num_insns <= BRANCH_COST && ! failed && temp1 != 0
1014 && GET_CODE (temp1) != CODE_LABEL;
1015 temp1 = NEXT_INSN (temp1))
1017 /* Ignore everything but an active insn. */
1018 if (GET_RTX_CLASS (GET_CODE (temp1)) != 'i'
1019 || GET_CODE (PATTERN (temp1)) == USE
1020 || GET_CODE (PATTERN (temp1)) == CLOBBER)
1023 /* If this was an unconditional jump, record it since we'll
1024 need to remove the BARRIER if we succeed. We can only
1025 have one such jump since there must be a label after
1026 the BARRIER and it's either ours, in which case it's the
1027 only one or some other, in which case we'd fail. */
1029 if (simplejump_p (temp1))
1030 changed_jump = temp1;
1032 /* See if we are allowed another insn and if this insn
1033 if one we think we may be able to handle. */
1034 if (++num_insns > BRANCH_COST
1036 || (temp2 = single_set (temp1)) == 0
1037 || side_effects_p (SET_SRC (temp2))
1038 || may_trap_p (SET_SRC (temp2)))
1041 validate_change (temp1, &SET_SRC (temp2),
1042 gen_rtx_IF_THEN_ELSE
1043 (GET_MODE (SET_DEST (temp2)),
1045 SET_SRC (temp2), SET_DEST (temp2)),
1048 if (modified_in_p (ourcond, temp1))
1052 /* If we've reached our jump label, haven't failed, and all
1053 the changes above are valid, we can delete this jump
1054 insn. Also remove a BARRIER after any jump that used
1055 to be unconditional and remove any REG_EQUAL or REG_EQUIV
1056 that might have previously been present on insns we
1057 made conditional. */
1058 if (temp1 == JUMP_LABEL (insn) && ! failed
1059 && apply_change_group ())
1061 for (temp1 = NEXT_INSN (insn); temp1 != JUMP_LABEL (insn);
1062 temp1 = NEXT_INSN (temp1))
1063 if (GET_RTX_CLASS (GET_CODE (temp1)) == 'i')
1064 for (temp2 = REG_NOTES (temp1); temp2 != 0;
1065 temp2 = XEXP (temp2, 1))
1066 if (REG_NOTE_KIND (temp2) == REG_EQUAL
1067 || REG_NOTE_KIND (temp2) == REG_EQUIV)
1068 remove_note (temp1, temp2);
1070 if (changed_jump != 0)
1072 if (GET_CODE (NEXT_INSN (changed_jump)) != BARRIER)
1075 delete_insn (NEXT_INSN (changed_jump));
1090 /* Try to use a conditional move (if the target has them), or a
1091 store-flag insn. If the target has conditional arithmetic as
1092 well as conditional move, the above code will have done something.
1093 Note that we prefer the above code since it is more general: the
1094 code below can make changes that require work to undo.
1096 The general case here is:
1098 1) x = a; if (...) x = b; and
1101 If the jump would be faster, the machine should not have defined
1102 the movcc or scc insns!. These cases are often made by the
1103 previous optimization.
1105 The second case is treated as x = x; if (...) x = b;.
1107 INSN here is the jump around the store. We set:
1109 TEMP to the "x op= b;" insn.
1112 TEMP3 to A (X in the second case).
1113 TEMP4 to the condition being tested.
1114 TEMP5 to the earliest insn used to find the condition.
1115 TEMP6 to the SET of TEMP. */
1117 if (/* We can't do this after reload has completed. */
1119 #ifdef HAVE_conditional_arithmetic
1120 /* Defer this until after CSE so the above code gets the
1121 first crack at it. */
1124 && this_is_condjump && ! this_is_simplejump
1125 /* Set TEMP to the "x = b;" insn. */
1126 && (temp = next_nonnote_insn (insn)) != 0
1127 && GET_CODE (temp) == INSN
1128 && (temp6 = single_set (temp)) != NULL_RTX
1129 && GET_CODE (temp1 = SET_DEST (temp6)) == REG
1130 && (! SMALL_REGISTER_CLASSES
1131 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
1132 && ! side_effects_p (temp2 = SET_SRC (temp6))
1133 && ! may_trap_p (temp2)
1134 /* Allow either form, but prefer the former if both apply.
1135 There is no point in using the old value of TEMP1 if
1136 it is a register, since cse will alias them. It can
1137 lose if the old value were a hard register since CSE
1138 won't replace hard registers. Avoid using TEMP3 if
1139 small register classes and it is a hard register. */
1140 && (((temp3 = reg_set_last (temp1, insn)) != 0
1141 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
1142 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
1143 /* Make the latter case look like x = x; if (...) x = b; */
1144 || (temp3 = temp1, 1))
1145 /* INSN must either branch to the insn after TEMP or the insn
1146 after TEMP must branch to the same place as INSN. */
1147 && (reallabelprev == temp
1148 || ((temp4 = next_active_insn (temp)) != 0
1149 && simplejump_p (temp4)
1150 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1151 && (temp4 = get_condition (insn, &temp5)) != 0
1152 /* We must be comparing objects whose modes imply the size.
1153 We could handle BLKmode if (1) emit_store_flag could
1154 and (2) we could find the size reliably. */
1155 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1156 /* Even if branches are cheap, the store_flag optimization
1157 can win when the operation to be performed can be
1158 expressed directly. */
1160 /* If the previous insn sets CC0 and something else, we can't
1161 do this since we are going to delete that insn. */
1163 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1164 && GET_CODE (temp6) == INSN
1165 && (sets_cc0_p (PATTERN (temp6)) == -1
1166 || (sets_cc0_p (PATTERN (temp6)) == 1
1167 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1171 #ifdef HAVE_conditional_move
1172 /* First try a conditional move. */
1174 enum rtx_code code = GET_CODE (temp4);
1176 rtx cond0, cond1, aval, bval;
1177 rtx target, new_insn;
1179 /* Copy the compared variables into cond0 and cond1, so that
1180 any side effects performed in or after the old comparison,
1181 will not affect our compare which will come later. */
1182 /* ??? Is it possible to just use the comparison in the jump
1183 insn? After all, we're going to delete it. We'd have
1184 to modify emit_conditional_move to take a comparison rtx
1185 instead or write a new function. */
1186 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1187 /* We want the target to be able to simplify comparisons with
1188 zero (and maybe other constants as well), so don't create
1189 pseudos for them. There's no need to either. */
1190 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1191 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1192 cond1 = XEXP (temp4, 1);
1194 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1196 /* Careful about copying these values -- an IOR or what may
1197 need to do other things, like clobber flags. */
1198 /* ??? Assume for the moment that AVAL is ok. */
1203 /* We're dealing with a single_set insn with no side effects
1204 on SET_SRC. We do need to be reasonably certain that if
1205 we need to force BVAL into a register that we won't
1206 clobber the flags -- general_operand should suffice. */
1207 if (general_operand (temp2, GET_MODE (var)))
1211 bval = gen_reg_rtx (GET_MODE (var));
1212 new_insn = copy_rtx (temp);
1213 temp6 = single_set (new_insn);
1214 SET_DEST (temp6) = bval;
1215 emit_insn (PATTERN (new_insn));
1218 target = emit_conditional_move (var, code,
1219 cond0, cond1, VOIDmode,
1220 aval, bval, GET_MODE (var),
1221 (code == LTU || code == GEU
1222 || code == LEU || code == GTU));
1226 rtx seq1, seq2, last;
1229 /* Save the conditional move sequence but don't emit it
1230 yet. On some machines, like the alpha, it is possible
1231 that temp5 == insn, so next generate the sequence that
1232 saves the compared values and then emit both
1233 sequences ensuring seq1 occurs before seq2. */
1234 seq2 = get_insns ();
1237 /* "Now that we can't fail..." Famous last words.
1238 Generate the copy insns that preserve the compared
1241 emit_move_insn (cond0, XEXP (temp4, 0));
1242 if (cond1 != XEXP (temp4, 1))
1243 emit_move_insn (cond1, XEXP (temp4, 1));
1244 seq1 = get_insns ();
1247 /* Validate the sequence -- this may be some weird
1248 bit-extract-and-test instruction for which there
1249 exists no complimentary bit-extract insn. */
1251 for (last = seq1; last ; last = NEXT_INSN (last))
1252 if (recog_memoized (last) < 0)
1260 emit_insns_before (seq1, temp5);
1262 /* Insert conditional move after insn, to be sure
1263 that the jump and a possible compare won't be
1265 last = emit_insns_after (seq2, insn);
1267 /* ??? We can also delete the insn that sets X to A.
1268 Flow will do it too though. */
1270 next = NEXT_INSN (insn);
1275 reg_scan_update (seq1, NEXT_INSN (last),
1277 old_max_reg = max_reg_num ();
1289 /* That didn't work, try a store-flag insn.
1291 We further divide the cases into:
1293 1) x = a; if (...) x = b; and either A or B is zero,
1294 2) if (...) x = 0; and jumps are expensive,
1295 3) x = a; if (...) x = b; and A and B are constants where all
1296 the set bits in A are also set in B and jumps are expensive,
1297 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1299 5) if (...) x = b; if jumps are even more expensive. */
1301 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1302 && ((GET_CODE (temp3) == CONST_INT)
1303 /* Make the latter case look like
1304 x = x; if (...) x = 0; */
1307 && temp2 == const0_rtx)
1308 || BRANCH_COST >= 3)))
1309 /* If B is zero, OK; if A is zero, can only do (1) if we
1310 can reverse the condition. See if (3) applies possibly
1311 by reversing the condition. Prefer reversing to (4) when
1312 branches are very expensive. */
1313 && (((BRANCH_COST >= 2
1314 || STORE_FLAG_VALUE == -1
1315 || (STORE_FLAG_VALUE == 1
1316 /* Check that the mask is a power of two,
1317 so that it can probably be generated
1319 && GET_CODE (temp3) == CONST_INT
1320 && exact_log2 (INTVAL (temp3)) >= 0))
1321 && (reversep = 0, temp2 == const0_rtx))
1322 || ((BRANCH_COST >= 2
1323 || STORE_FLAG_VALUE == -1
1324 || (STORE_FLAG_VALUE == 1
1325 && GET_CODE (temp2) == CONST_INT
1326 && exact_log2 (INTVAL (temp2)) >= 0))
1327 && temp3 == const0_rtx
1328 && (reversep = can_reverse_comparison_p (temp4, insn)))
1329 || (BRANCH_COST >= 2
1330 && GET_CODE (temp2) == CONST_INT
1331 && GET_CODE (temp3) == CONST_INT
1332 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1333 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1334 && (reversep = can_reverse_comparison_p (temp4,
1336 || BRANCH_COST >= 3)
1339 enum rtx_code code = GET_CODE (temp4);
1340 rtx uval, cval, var = temp1;
1344 /* If necessary, reverse the condition. */
1346 code = reverse_condition (code), uval = temp2, cval = temp3;
1348 uval = temp3, cval = temp2;
1350 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1351 is the constant 1, it is best to just compute the result
1352 directly. If UVAL is constant and STORE_FLAG_VALUE
1353 includes all of its bits, it is best to compute the flag
1354 value unnormalized and `and' it with UVAL. Otherwise,
1355 normalize to -1 and `and' with UVAL. */
1356 normalizep = (cval != const0_rtx ? -1
1357 : (uval == const1_rtx ? 1
1358 : (GET_CODE (uval) == CONST_INT
1359 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1362 /* We will be putting the store-flag insn immediately in
1363 front of the comparison that was originally being done,
1364 so we know all the variables in TEMP4 will be valid.
1365 However, this might be in front of the assignment of
1366 A to VAR. If it is, it would clobber the store-flag
1367 we will be emitting.
1369 Therefore, emit into a temporary which will be copied to
1370 VAR immediately after TEMP. */
1373 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1374 XEXP (temp4, 0), XEXP (temp4, 1),
1376 (code == LTU || code == LEU
1377 || code == GEU || code == GTU),
1387 /* Put the store-flag insns in front of the first insn
1388 used to compute the condition to ensure that we
1389 use the same values of them as the current
1390 comparison. However, the remainder of the insns we
1391 generate will be placed directly in front of the
1392 jump insn, in case any of the pseudos we use
1393 are modified earlier. */
1395 emit_insns_before (seq, temp5);
1399 /* Both CVAL and UVAL are non-zero. */
1400 if (cval != const0_rtx && uval != const0_rtx)
1404 tem1 = expand_and (uval, target, NULL_RTX);
1405 if (GET_CODE (cval) == CONST_INT
1406 && GET_CODE (uval) == CONST_INT
1407 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1411 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1412 target, NULL_RTX, 0);
1413 tem2 = expand_and (cval, tem2,
1414 (GET_CODE (tem2) == REG
1418 /* If we usually make new pseudos, do so here. This
1419 turns out to help machines that have conditional
1421 /* ??? Conditional moves have already been handled.
1422 This may be obsolete. */
1424 if (flag_expensive_optimizations)
1427 target = expand_binop (GET_MODE (var), ior_optab,
1431 else if (normalizep != 1)
1433 /* We know that either CVAL or UVAL is zero. If
1434 UVAL is zero, negate TARGET and `and' with CVAL.
1435 Otherwise, `and' with UVAL. */
1436 if (uval == const0_rtx)
1438 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1439 target, NULL_RTX, 0);
1443 target = expand_and (uval, target,
1444 (GET_CODE (target) == REG
1445 && ! preserve_subexpressions_p ()
1446 ? target : NULL_RTX));
1449 emit_move_insn (var, target);
1453 /* If INSN uses CC0, we must not separate it from the
1454 insn that sets cc0. */
1455 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1456 before = prev_nonnote_insn (before);
1458 emit_insns_before (seq, before);
1461 next = NEXT_INSN (insn);
1466 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1467 old_max_reg = max_reg_num ();
1478 /* If branches are expensive, convert
1479 if (foo) bar++; to bar += (foo != 0);
1480 and similarly for "bar--;"
1482 INSN is the conditional branch around the arithmetic. We set:
1484 TEMP is the arithmetic insn.
1485 TEMP1 is the SET doing the arithmetic.
1486 TEMP2 is the operand being incremented or decremented.
1487 TEMP3 to the condition being tested.
1488 TEMP4 to the earliest insn used to find the condition. */
1490 if ((BRANCH_COST >= 2
1498 && ! reload_completed
1499 && this_is_condjump && ! this_is_simplejump
1500 && (temp = next_nonnote_insn (insn)) != 0
1501 && (temp1 = single_set (temp)) != 0
1502 && (temp2 = SET_DEST (temp1),
1503 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1504 && GET_CODE (SET_SRC (temp1)) == PLUS
1505 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1506 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1507 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1508 && ! side_effects_p (temp2)
1509 && ! may_trap_p (temp2)
1510 /* INSN must either branch to the insn after TEMP or the insn
1511 after TEMP must branch to the same place as INSN. */
1512 && (reallabelprev == temp
1513 || ((temp3 = next_active_insn (temp)) != 0
1514 && simplejump_p (temp3)
1515 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1516 && (temp3 = get_condition (insn, &temp4)) != 0
1517 /* We must be comparing objects whose modes imply the size.
1518 We could handle BLKmode if (1) emit_store_flag could
1519 and (2) we could find the size reliably. */
1520 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1521 && can_reverse_comparison_p (temp3, insn))
1523 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1524 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1528 /* It must be the case that TEMP2 is not modified in the range
1529 [TEMP4, INSN). The one exception we make is if the insn
1530 before INSN sets TEMP2 to something which is also unchanged
1531 in that range. In that case, we can move the initialization
1532 into our sequence. */
1534 if ((temp5 = prev_active_insn (insn)) != 0
1535 && no_labels_between_p (temp5, insn)
1536 && GET_CODE (temp5) == INSN
1537 && (temp6 = single_set (temp5)) != 0
1538 && rtx_equal_p (temp2, SET_DEST (temp6))
1539 && (CONSTANT_P (SET_SRC (temp6))
1540 || GET_CODE (SET_SRC (temp6)) == REG
1541 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1543 emit_insn (PATTERN (temp5));
1545 init = SET_SRC (temp6);
1548 if (CONSTANT_P (init)
1549 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1550 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1551 XEXP (temp3, 0), XEXP (temp3, 1),
1553 (code == LTU || code == LEU
1554 || code == GTU || code == GEU), 1);
1556 /* If we can do the store-flag, do the addition or
1560 target = expand_binop (GET_MODE (temp2),
1561 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1562 ? add_optab : sub_optab),
1563 temp2, target, temp2, 0, OPTAB_WIDEN);
1567 /* Put the result back in temp2 in case it isn't already.
1568 Then replace the jump, possible a CC0-setting insn in
1569 front of the jump, and TEMP, with the sequence we have
1572 if (target != temp2)
1573 emit_move_insn (temp2, target);
1578 emit_insns_before (seq, temp4);
1582 delete_insn (init_insn);
1584 next = NEXT_INSN (insn);
1586 delete_insn (prev_nonnote_insn (insn));
1592 reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
1593 old_max_reg = max_reg_num ();
1603 /* Simplify if (...) x = 1; else {...} if (x) ...
1604 We recognize this case scanning backwards as well.
1606 TEMP is the assignment to x;
1607 TEMP1 is the label at the head of the second if. */
1608 /* ?? This should call get_condition to find the values being
1609 compared, instead of looking for a COMPARE insn when HAVE_cc0
1610 is not defined. This would allow it to work on the m88k. */
1611 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1612 is not defined and the condition is tested by a separate compare
1613 insn. This is because the code below assumes that the result
1614 of the compare dies in the following branch.
1616 Not only that, but there might be other insns between the
1617 compare and branch whose results are live. Those insns need
1620 A way to fix this is to move the insns at JUMP_LABEL (insn)
1621 to before INSN. If we are running before flow, they will
1622 be deleted if they aren't needed. But this doesn't work
1625 This is really a special-case of jump threading, anyway. The
1626 right thing to do is to replace this and jump threading with
1627 much simpler code in cse.
1629 This code has been turned off in the non-cc0 case in the
1633 else if (this_is_simplejump
1634 /* Safe to skip USE and CLOBBER insns here
1635 since they will not be deleted. */
1636 && (temp = prev_active_insn (insn))
1637 && no_labels_between_p (temp, insn)
1638 && GET_CODE (temp) == INSN
1639 && GET_CODE (PATTERN (temp)) == SET
1640 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1641 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1642 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1643 /* If we find that the next value tested is `x'
1644 (TEMP1 is the insn where this happens), win. */
1645 && GET_CODE (temp1) == INSN
1646 && GET_CODE (PATTERN (temp1)) == SET
1648 /* Does temp1 `tst' the value of x? */
1649 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1650 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1651 && (temp1 = next_nonnote_insn (temp1))
1653 /* Does temp1 compare the value of x against zero? */
1654 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1655 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1656 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1657 == SET_DEST (PATTERN (temp)))
1658 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1659 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1661 && condjump_p (temp1))
1663 /* Get the if_then_else from the condjump. */
1664 rtx choice = SET_SRC (PATTERN (temp1));
1665 if (GET_CODE (choice) == IF_THEN_ELSE)
1667 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1668 rtx val = SET_SRC (PATTERN (temp));
1670 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1674 if (cond == const_true_rtx)
1675 ultimate = XEXP (choice, 1);
1676 else if (cond == const0_rtx)
1677 ultimate = XEXP (choice, 2);
1681 if (ultimate == pc_rtx)
1682 ultimate = get_label_after (temp1);
1683 else if (ultimate && GET_CODE (ultimate) != RETURN)
1684 ultimate = XEXP (ultimate, 0);
1686 if (ultimate && JUMP_LABEL(insn) != ultimate)
1687 changed |= redirect_jump (insn, ultimate);
1693 /* @@ This needs a bit of work before it will be right.
1695 Any type of comparison can be accepted for the first and
1696 second compare. When rewriting the first jump, we must
1697 compute the what conditions can reach label3, and use the
1698 appropriate code. We can not simply reverse/swap the code
1699 of the first jump. In some cases, the second jump must be
1703 < == converts to > ==
1704 < != converts to == >
1707 If the code is written to only accept an '==' test for the second
1708 compare, then all that needs to be done is to swap the condition
1709 of the first branch.
1711 It is questionable whether we want this optimization anyways,
1712 since if the user wrote code like this because he/she knew that
1713 the jump to label1 is taken most of the time, then rewriting
1714 this gives slower code. */
1715 /* @@ This should call get_condition to find the values being
1716 compared, instead of looking for a COMPARE insn when HAVE_cc0
1717 is not defined. This would allow it to work on the m88k. */
1718 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1719 is not defined and the condition is tested by a separate compare
1720 insn. This is because the code below assumes that the result
1721 of the compare dies in the following branch. */
1723 /* Simplify test a ~= b
1737 where ~= is an inequality, e.g. >, and ~~= is the swapped
1740 We recognize this case scanning backwards.
1742 TEMP is the conditional jump to `label2';
1743 TEMP1 is the test for `a == b';
1744 TEMP2 is the conditional jump to `label1';
1745 TEMP3 is the test for `a ~= b'. */
1746 else if (this_is_simplejump
1747 && (temp = prev_active_insn (insn))
1748 && no_labels_between_p (temp, insn)
1749 && condjump_p (temp)
1750 && (temp1 = prev_active_insn (temp))
1751 && no_labels_between_p (temp1, temp)
1752 && GET_CODE (temp1) == INSN
1753 && GET_CODE (PATTERN (temp1)) == SET
1755 && sets_cc0_p (PATTERN (temp1)) == 1
1757 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1758 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1759 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1761 && (temp2 = prev_active_insn (temp1))
1762 && no_labels_between_p (temp2, temp1)
1763 && condjump_p (temp2)
1764 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1765 && (temp3 = prev_active_insn (temp2))
1766 && no_labels_between_p (temp3, temp2)
1767 && GET_CODE (PATTERN (temp3)) == SET
1768 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1769 SET_DEST (PATTERN (temp1)))
1770 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1771 SET_SRC (PATTERN (temp3)))
1772 && ! inequality_comparisons_p (PATTERN (temp))
1773 && inequality_comparisons_p (PATTERN (temp2)))
1775 rtx fallthrough_label = JUMP_LABEL (temp2);
1777 ++LABEL_NUSES (fallthrough_label);
1778 if (swap_jump (temp2, JUMP_LABEL (insn)))
1784 if (--LABEL_NUSES (fallthrough_label) == 0)
1785 delete_insn (fallthrough_label);
1788 /* Simplify if (...) {... x = 1;} if (x) ...
1790 We recognize this case backwards.
1792 TEMP is the test of `x';
1793 TEMP1 is the assignment to `x' at the end of the
1794 previous statement. */
1795 /* @@ This should call get_condition to find the values being
1796 compared, instead of looking for a COMPARE insn when HAVE_cc0
1797 is not defined. This would allow it to work on the m88k. */
1798 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1799 is not defined and the condition is tested by a separate compare
1800 insn. This is because the code below assumes that the result
1801 of the compare dies in the following branch. */
1803 /* ??? This has to be turned off. The problem is that the
1804 unconditional jump might indirectly end up branching to the
1805 label between TEMP1 and TEMP. We can't detect this, in general,
1806 since it may become a jump to there after further optimizations.
1807 If that jump is done, it will be deleted, so we will retry
1808 this optimization in the next pass, thus an infinite loop.
1810 The present code prevents this by putting the jump after the
1811 label, but this is not logically correct. */
1813 else if (this_is_condjump
1814 /* Safe to skip USE and CLOBBER insns here
1815 since they will not be deleted. */
1816 && (temp = prev_active_insn (insn))
1817 && no_labels_between_p (temp, insn)
1818 && GET_CODE (temp) == INSN
1819 && GET_CODE (PATTERN (temp)) == SET
1821 && sets_cc0_p (PATTERN (temp)) == 1
1822 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1824 /* Temp must be a compare insn, we can not accept a register
1825 to register move here, since it may not be simply a
1827 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1828 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1829 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1830 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1831 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1833 /* May skip USE or CLOBBER insns here
1834 for checking for opportunity, since we
1835 take care of them later. */
1836 && (temp1 = prev_active_insn (temp))
1837 && GET_CODE (temp1) == INSN
1838 && GET_CODE (PATTERN (temp1)) == SET
1840 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1842 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1843 == SET_DEST (PATTERN (temp1)))
1845 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1846 /* If this isn't true, cse will do the job. */
1847 && ! no_labels_between_p (temp1, temp))
1849 /* Get the if_then_else from the condjump. */
1850 rtx choice = SET_SRC (PATTERN (insn));
1851 if (GET_CODE (choice) == IF_THEN_ELSE
1852 && (GET_CODE (XEXP (choice, 0)) == EQ
1853 || GET_CODE (XEXP (choice, 0)) == NE))
1855 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1860 /* Get the place that condjump will jump to
1861 if it is reached from here. */
1862 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1864 ultimate = XEXP (choice, 1);
1866 ultimate = XEXP (choice, 2);
1867 /* Get it as a CODE_LABEL. */
1868 if (ultimate == pc_rtx)
1869 ultimate = get_label_after (insn);
1871 /* Get the label out of the LABEL_REF. */
1872 ultimate = XEXP (ultimate, 0);
1874 /* Insert the jump immediately before TEMP, specifically
1875 after the label that is between TEMP1 and TEMP. */
1876 last_insn = PREV_INSN (temp);
1878 /* If we would be branching to the next insn, the jump
1879 would immediately be deleted and the re-inserted in
1880 a subsequent pass over the code. So don't do anything
1882 if (next_active_insn (last_insn)
1883 != next_active_insn (ultimate))
1885 emit_barrier_after (last_insn);
1886 p = emit_jump_insn_after (gen_jump (ultimate),
1888 JUMP_LABEL (p) = ultimate;
1889 ++LABEL_NUSES (ultimate);
1890 if (INSN_UID (ultimate) < max_jump_chain
1891 && INSN_CODE (p) < max_jump_chain)
1893 jump_chain[INSN_UID (p)]
1894 = jump_chain[INSN_UID (ultimate)];
1895 jump_chain[INSN_UID (ultimate)] = p;
1904 /* Detect a conditional jump jumping over an unconditional trap. */
1906 && this_is_condjump && ! this_is_simplejump
1907 && reallabelprev != 0
1908 && GET_CODE (reallabelprev) == INSN
1909 && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
1910 && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
1911 && prev_active_insn (reallabelprev) == insn
1912 && no_labels_between_p (insn, reallabelprev)
1913 && (temp2 = get_condition (insn, &temp4))
1914 && can_reverse_comparison_p (temp2, insn))
1916 rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
1917 XEXP (temp2, 0), XEXP (temp2, 1),
1918 TRAP_CODE (PATTERN (reallabelprev)));
1922 emit_insn_before (new, temp4);
1923 delete_insn (reallabelprev);
1929 /* Detect a jump jumping to an unconditional trap. */
1930 else if (HAVE_trap && this_is_condjump
1931 && (temp = next_active_insn (JUMP_LABEL (insn)))
1932 && GET_CODE (temp) == INSN
1933 && GET_CODE (PATTERN (temp)) == TRAP_IF
1934 && (this_is_simplejump
1935 || (temp2 = get_condition (insn, &temp4))))
1937 rtx tc = TRAP_CONDITION (PATTERN (temp));
1939 if (tc == const_true_rtx
1940 || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
1943 /* Replace an unconditional jump to a trap with a trap. */
1944 if (this_is_simplejump)
1946 emit_barrier_after (emit_insn_before (gen_trap (), insn));
1951 new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
1953 TRAP_CODE (PATTERN (temp)));
1956 emit_insn_before (new, temp4);
1962 /* If the trap condition and jump condition are mutually
1963 exclusive, redirect the jump to the following insn. */
1964 else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
1965 && ! this_is_simplejump
1966 && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
1967 && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
1968 && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
1969 && redirect_jump (insn, get_label_after (temp)))
1978 /* Detect a jump to a jump. */
1980 /* Look for if (foo) bar; else break; */
1981 /* The insns look like this:
1982 insn = condjump label1;
1983 ...range1 (some insns)...
1986 ...range2 (some insns)...
1987 jump somewhere unconditionally
1990 rtx label1 = next_label (insn);
1991 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1992 /* Don't do this optimization on the first round, so that
1993 jump-around-a-jump gets simplified before we ask here
1994 whether a jump is unconditional.
1996 Also don't do it when we are called after reload since
1997 it will confuse reorg. */
1999 && (reload_completed ? ! flag_delayed_branch : 1)
2000 /* Make sure INSN is something we can invert. */
2001 && condjump_p (insn)
2003 && JUMP_LABEL (insn) == label1
2004 && LABEL_NUSES (label1) == 1
2005 && GET_CODE (range1end) == JUMP_INSN
2006 && simplejump_p (range1end))
2008 rtx label2 = next_label (label1);
2009 rtx range2end = label2 ? prev_active_insn (label2) : 0;
2010 if (range1end != range2end
2011 && JUMP_LABEL (range1end) == label2
2012 && GET_CODE (range2end) == JUMP_INSN
2013 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
2014 /* Invert the jump condition, so we
2015 still execute the same insns in each case. */
2016 && invert_jump (insn, label1))
2018 rtx range1beg = next_active_insn (insn);
2019 rtx range2beg = next_active_insn (label1);
2020 rtx range1after, range2after;
2021 rtx range1before, range2before;
2024 /* Include in each range any notes before it, to be
2025 sure that we get the line number note if any, even
2026 if there are other notes here. */
2027 while (PREV_INSN (range1beg)
2028 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
2029 range1beg = PREV_INSN (range1beg);
2031 while (PREV_INSN (range2beg)
2032 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
2033 range2beg = PREV_INSN (range2beg);
2035 /* Don't move NOTEs for blocks or loops; shift them
2036 outside the ranges, where they'll stay put. */
2037 range1beg = squeeze_notes (range1beg, range1end);
2038 range2beg = squeeze_notes (range2beg, range2end);
2040 /* Get current surrounds of the 2 ranges. */
2041 range1before = PREV_INSN (range1beg);
2042 range2before = PREV_INSN (range2beg);
2043 range1after = NEXT_INSN (range1end);
2044 range2after = NEXT_INSN (range2end);
2046 /* Splice range2 where range1 was. */
2047 NEXT_INSN (range1before) = range2beg;
2048 PREV_INSN (range2beg) = range1before;
2049 NEXT_INSN (range2end) = range1after;
2050 PREV_INSN (range1after) = range2end;
2051 /* Splice range1 where range2 was. */
2052 NEXT_INSN (range2before) = range1beg;
2053 PREV_INSN (range1beg) = range2before;
2054 NEXT_INSN (range1end) = range2after;
2055 PREV_INSN (range2after) = range1end;
2057 /* Check for a loop end note between the end of
2058 range2, and the next code label. If there is one,
2059 then what we have really seen is
2060 if (foo) break; end_of_loop;
2061 and moved the break sequence outside the loop.
2062 We must move the LOOP_END note to where the
2063 loop really ends now, or we will confuse loop
2064 optimization. Stop if we find a LOOP_BEG note
2065 first, since we don't want to move the LOOP_END
2066 note in that case. */
2067 for (;range2after != label2; range2after = rangenext)
2069 rangenext = NEXT_INSN (range2after);
2070 if (GET_CODE (range2after) == NOTE)
2072 if (NOTE_LINE_NUMBER (range2after)
2073 == NOTE_INSN_LOOP_END)
2075 NEXT_INSN (PREV_INSN (range2after))
2077 PREV_INSN (rangenext)
2078 = PREV_INSN (range2after);
2079 PREV_INSN (range2after)
2080 = PREV_INSN (range1beg);
2081 NEXT_INSN (range2after) = range1beg;
2082 NEXT_INSN (PREV_INSN (range1beg))
2084 PREV_INSN (range1beg) = range2after;
2086 else if (NOTE_LINE_NUMBER (range2after)
2087 == NOTE_INSN_LOOP_BEG)
2097 /* Now that the jump has been tensioned,
2098 try cross jumping: check for identical code
2099 before the jump and before its target label. */
2101 /* First, cross jumping of conditional jumps: */
2103 if (cross_jump && condjump_p (insn))
2105 rtx newjpos, newlpos;
2106 rtx x = prev_real_insn (JUMP_LABEL (insn));
2108 /* A conditional jump may be crossjumped
2109 only if the place it jumps to follows
2110 an opposing jump that comes back here. */
2112 if (x != 0 && ! jump_back_p (x, insn))
2113 /* We have no opposing jump;
2114 cannot cross jump this insn. */
2118 /* TARGET is nonzero if it is ok to cross jump
2119 to code before TARGET. If so, see if matches. */
2121 find_cross_jump (insn, x, 2,
2122 &newjpos, &newlpos);
2126 do_cross_jump (insn, newjpos, newlpos);
2127 /* Make the old conditional jump
2128 into an unconditional one. */
2129 SET_SRC (PATTERN (insn))
2130 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
2131 INSN_CODE (insn) = -1;
2132 emit_barrier_after (insn);
2133 /* Add to jump_chain unless this is a new label
2134 whose UID is too large. */
2135 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
2137 jump_chain[INSN_UID (insn)]
2138 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2139 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2146 /* Cross jumping of unconditional jumps:
2147 a few differences. */
2149 if (cross_jump && simplejump_p (insn))
2151 rtx newjpos, newlpos;
2156 /* TARGET is nonzero if it is ok to cross jump
2157 to code before TARGET. If so, see if matches. */
2158 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2159 &newjpos, &newlpos);
2161 /* If cannot cross jump to code before the label,
2162 see if we can cross jump to another jump to
2164 /* Try each other jump to this label. */
2165 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2166 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2167 target != 0 && newjpos == 0;
2168 target = jump_chain[INSN_UID (target)])
2170 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2171 /* Ignore TARGET if it's deleted. */
2172 && ! INSN_DELETED_P (target))
2173 find_cross_jump (insn, target, 2,
2174 &newjpos, &newlpos);
2178 do_cross_jump (insn, newjpos, newlpos);
2184 /* This code was dead in the previous jump.c! */
2185 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2187 /* Return insns all "jump to the same place"
2188 so we can cross-jump between any two of them. */
2190 rtx newjpos, newlpos, target;
2194 /* If cannot cross jump to code before the label,
2195 see if we can cross jump to another jump to
2197 /* Try each other jump to this label. */
2198 for (target = jump_chain[0];
2199 target != 0 && newjpos == 0;
2200 target = jump_chain[INSN_UID (target)])
2202 && ! INSN_DELETED_P (target)
2203 && GET_CODE (PATTERN (target)) == RETURN)
2204 find_cross_jump (insn, target, 2,
2205 &newjpos, &newlpos);
2209 do_cross_jump (insn, newjpos, newlpos);
2220 /* Delete extraneous line number notes.
2221 Note that two consecutive notes for different lines are not really
2222 extraneous. There should be some indication where that line belonged,
2223 even if it became empty. */
2228 for (insn = f; insn; insn = NEXT_INSN (insn))
2229 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2231 /* Delete this note if it is identical to previous note. */
2233 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2234 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2247 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2248 in front of it. If the machine allows it at this point (we might be
2249 after reload for a leaf routine), it will improve optimization for it
2250 to be there. We do this both here and at the start of this pass since
2251 the RETURN might have been deleted by some of our optimizations. */
2252 insn = get_last_insn ();
2253 while (insn && GET_CODE (insn) == NOTE)
2254 insn = PREV_INSN (insn);
2256 if (insn && GET_CODE (insn) != BARRIER)
2258 emit_jump_insn (gen_return ());
2264 /* CAN_REACH_END is persistent for each function. Once set it should
2265 not be cleared. This is especially true for the case where we
2266 delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
2267 the front-end before compiling each function. */
2268 if (calculate_can_reach_end (last_insn, 0, 1))
2271 /* Show JUMP_CHAIN no longer valid. */
2275 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
2276 notes whose labels don't occur in the insn any more. Returns the
2277 largest INSN_UID found. */
2282 int largest_uid = 0;
2285 for (insn = f; insn; insn = NEXT_INSN (insn))
2287 if (GET_CODE (insn) == CODE_LABEL)
2288 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
2289 else if (GET_CODE (insn) == JUMP_INSN)
2290 JUMP_LABEL (insn) = 0;
2291 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2295 for (note = REG_NOTES (insn); note; note = next)
2297 next = XEXP (note, 1);
2298 if (REG_NOTE_KIND (note) == REG_LABEL
2299 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
2300 remove_note (insn, note);
2303 if (INSN_UID (insn) > largest_uid)
2304 largest_uid = INSN_UID (insn);
2310 /* Delete insns following barriers, up to next label.
2312 Also delete no-op jumps created by gcse. */
2314 delete_barrier_successors (f)
2319 for (insn = f; insn;)
2321 if (GET_CODE (insn) == BARRIER)
2323 insn = NEXT_INSN (insn);
2325 never_reached_warning (insn);
2327 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
2329 if (GET_CODE (insn) == NOTE
2330 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2331 insn = NEXT_INSN (insn);
2333 insn = delete_insn (insn);
2335 /* INSN is now the code_label. */
2337 /* Also remove (set (pc) (pc)) insns which can be created by
2338 gcse. We eliminate such insns now to avoid having them
2339 cause problems later. */
2340 else if (GET_CODE (insn) == JUMP_INSN
2341 && GET_CODE (PATTERN (insn)) == SET
2342 && SET_SRC (PATTERN (insn)) == pc_rtx
2343 && SET_DEST (PATTERN (insn)) == pc_rtx)
2344 insn = delete_insn (insn);
2347 insn = NEXT_INSN (insn);
2351 /* Mark the label each jump jumps to.
2352 Combine consecutive labels, and count uses of labels.
2354 For each label, make a chain (using `jump_chain')
2355 of all the *unconditional* jumps that jump to it;
2356 also make a chain of all returns.
2358 CROSS_JUMP indicates whether we are doing cross jumping
2359 and if we are whether we will be paying attention to
2360 death notes or not. */
2363 mark_all_labels (f, cross_jump)
2369 for (insn = f; insn; insn = NEXT_INSN (insn))
2370 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2372 mark_jump_label (PATTERN (insn), insn, cross_jump);
2373 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
2375 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
2377 jump_chain[INSN_UID (insn)]
2378 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2379 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2381 if (GET_CODE (PATTERN (insn)) == RETURN)
2383 jump_chain[INSN_UID (insn)] = jump_chain[0];
2384 jump_chain[0] = insn;
2390 /* Delete all labels already not referenced.
2391 Also find and return the last insn. */
2394 delete_unreferenced_labels (f)
2397 rtx final = NULL_RTX;
2400 for (insn = f; insn; )
2402 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
2403 insn = delete_insn (insn);
2407 insn = NEXT_INSN (insn);
2414 /* Delete various simple forms of moves which have no necessary
2418 delete_noop_moves (f)
2423 for (insn = f; insn; )
2425 next = NEXT_INSN (insn);
2427 if (GET_CODE (insn) == INSN)
2429 register rtx body = PATTERN (insn);
2431 /* Combine stack_adjusts with following push_insns. */
2432 #ifdef PUSH_ROUNDING
2433 if (GET_CODE (body) == SET
2434 && SET_DEST (body) == stack_pointer_rtx
2435 && GET_CODE (SET_SRC (body)) == PLUS
2436 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
2437 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
2438 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
2441 rtx stack_adjust_insn = insn;
2442 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
2443 int total_pushed = 0;
2446 /* Find all successive push insns. */
2448 /* Don't convert more than three pushes;
2449 that starts adding too many displaced addresses
2450 and the whole thing starts becoming a losing
2455 p = next_nonnote_insn (p);
2456 if (p == 0 || GET_CODE (p) != INSN)
2458 pbody = PATTERN (p);
2459 if (GET_CODE (pbody) != SET)
2461 dest = SET_DEST (pbody);
2462 /* Allow a no-op move between the adjust and the push. */
2463 if (GET_CODE (dest) == REG
2464 && GET_CODE (SET_SRC (pbody)) == REG
2465 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2467 if (! (GET_CODE (dest) == MEM
2468 && GET_CODE (XEXP (dest, 0)) == POST_INC
2469 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2472 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
2473 > stack_adjust_amount)
2475 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2478 /* Discard the amount pushed from the stack adjust;
2479 maybe eliminate it entirely. */
2480 if (total_pushed >= stack_adjust_amount)
2482 delete_computation (stack_adjust_insn);
2483 total_pushed = stack_adjust_amount;
2486 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
2487 = GEN_INT (stack_adjust_amount - total_pushed);
2489 /* Change the appropriate push insns to ordinary stores. */
2491 while (total_pushed > 0)
2494 p = next_nonnote_insn (p);
2495 if (GET_CODE (p) != INSN)
2497 pbody = PATTERN (p);
2498 if (GET_CODE (pbody) != SET)
2500 dest = SET_DEST (pbody);
2501 /* Allow a no-op move between the adjust and the push. */
2502 if (GET_CODE (dest) == REG
2503 && GET_CODE (SET_SRC (pbody)) == REG
2504 && REGNO (dest) == REGNO (SET_SRC (pbody)))
2506 if (! (GET_CODE (dest) == MEM
2507 && GET_CODE (XEXP (dest, 0)) == POST_INC
2508 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
2510 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
2511 /* If this push doesn't fully fit in the space
2512 of the stack adjust that we deleted,
2513 make another stack adjust here for what we
2514 didn't use up. There should be peepholes
2515 to recognize the resulting sequence of insns. */
2516 if (total_pushed < 0)
2518 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
2519 GEN_INT (- total_pushed)),
2524 = plus_constant (stack_pointer_rtx, total_pushed);
2529 /* Detect and delete no-op move instructions
2530 resulting from not allocating a parameter in a register. */
2532 if (GET_CODE (body) == SET
2533 && (SET_DEST (body) == SET_SRC (body)
2534 || (GET_CODE (SET_DEST (body)) == MEM
2535 && GET_CODE (SET_SRC (body)) == MEM
2536 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
2537 && ! (GET_CODE (SET_DEST (body)) == MEM
2538 && MEM_VOLATILE_P (SET_DEST (body)))
2539 && ! (GET_CODE (SET_SRC (body)) == MEM
2540 && MEM_VOLATILE_P (SET_SRC (body))))
2541 delete_computation (insn);
2543 /* Detect and ignore no-op move instructions
2544 resulting from smart or fortuitous register allocation. */
2546 else if (GET_CODE (body) == SET)
2548 int sreg = true_regnum (SET_SRC (body));
2549 int dreg = true_regnum (SET_DEST (body));
2551 if (sreg == dreg && sreg >= 0)
2553 else if (sreg >= 0 && dreg >= 0)
2556 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
2557 sreg, NULL_PTR, dreg,
2558 GET_MODE (SET_SRC (body)));
2561 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
2563 /* DREG may have been the target of a REG_DEAD note in
2564 the insn which makes INSN redundant. If so, reorg
2565 would still think it is dead. So search for such a
2566 note and delete it if we find it. */
2567 if (! find_regno_note (insn, REG_UNUSED, dreg))
2568 for (trial = prev_nonnote_insn (insn);
2569 trial && GET_CODE (trial) != CODE_LABEL;
2570 trial = prev_nonnote_insn (trial))
2571 if (find_regno_note (trial, REG_DEAD, dreg))
2573 remove_death (dreg, trial);
2577 /* Deleting insn could lose a death-note for SREG. */
2578 if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
2580 /* Change this into a USE so that we won't emit
2581 code for it, but still can keep the note. */
2583 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
2584 INSN_CODE (insn) = -1;
2585 /* Remove all reg notes but the REG_DEAD one. */
2586 REG_NOTES (insn) = trial;
2587 XEXP (trial, 1) = NULL_RTX;
2593 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
2594 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
2596 GET_MODE (SET_DEST (body))))
2598 /* This handles the case where we have two consecutive
2599 assignments of the same constant to pseudos that didn't
2600 get a hard reg. Each SET from the constant will be
2601 converted into a SET of the spill register and an
2602 output reload will be made following it. This produces
2603 two loads of the same constant into the same spill
2608 /* Look back for a death note for the first reg.
2609 If there is one, it is no longer accurate. */
2610 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
2612 if ((GET_CODE (in_insn) == INSN
2613 || GET_CODE (in_insn) == JUMP_INSN)
2614 && find_regno_note (in_insn, REG_DEAD, dreg))
2616 remove_death (dreg, in_insn);
2619 in_insn = PREV_INSN (in_insn);
2622 /* Delete the second load of the value. */
2626 else if (GET_CODE (body) == PARALLEL)
2628 /* If each part is a set between two identical registers or
2629 a USE or CLOBBER, delete the insn. */
2633 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
2635 tem = XVECEXP (body, 0, i);
2636 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
2639 if (GET_CODE (tem) != SET
2640 || (sreg = true_regnum (SET_SRC (tem))) < 0
2641 || (dreg = true_regnum (SET_DEST (tem))) < 0
2649 /* Also delete insns to store bit fields if they are no-ops. */
2650 /* Not worth the hair to detect this in the big-endian case. */
2651 else if (! BYTES_BIG_ENDIAN
2652 && GET_CODE (body) == SET
2653 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
2654 && XEXP (SET_DEST (body), 2) == const0_rtx
2655 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
2656 && ! (GET_CODE (SET_SRC (body)) == MEM
2657 && MEM_VOLATILE_P (SET_SRC (body))))
2664 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2665 If so indicate that this function can drop off the end by returning
2668 CHECK_DELETED indicates whether we must check if the note being
2669 searched for has the deleted flag set.
2671 DELETE_FINAL_NOTE indicates whether we should delete the note
2675 calculate_can_reach_end (last, check_deleted, delete_final_note)
2678 int delete_final_note;
2683 while (insn != NULL_RTX)
2687 /* One label can follow the end-note: the return label. */
2688 if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2690 /* Ordinary insns can follow it if returning a structure. */
2691 else if (GET_CODE (insn) == INSN)
2693 /* If machine uses explicit RETURN insns, no epilogue,
2694 then one of them follows the note. */
2695 else if (GET_CODE (insn) == JUMP_INSN
2696 && GET_CODE (PATTERN (insn)) == RETURN)
2698 /* A barrier can follow the return insn. */
2699 else if (GET_CODE (insn) == BARRIER)
2701 /* Other kinds of notes can follow also. */
2702 else if (GET_CODE (insn) == NOTE
2703 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
2709 insn = PREV_INSN (insn);
2712 /* See if we backed up to the appropriate type of note. */
2713 if (insn != NULL_RTX
2714 && GET_CODE (insn) == NOTE
2715 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
2716 && (check_deleted == 0
2717 || ! INSN_DELETED_P (insn)))
2719 if (delete_final_note)
2727 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2728 jump. Assume that this unconditional jump is to the exit test code. If
2729 the code is sufficiently simple, make a copy of it before INSN,
2730 followed by a jump to the exit of the loop. Then delete the unconditional
2733 Return 1 if we made the change, else 0.
2735 This is only safe immediately after a regscan pass because it uses the
2736 values of regno_first_uid and regno_last_uid. */
2739 duplicate_loop_exit_test (loop_start)
2742 rtx insn, set, reg, p, link;
2743 rtx copy = 0, first_copy = 0;
2745 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2747 int max_reg = max_reg_num ();
2750 /* Scan the exit code. We do not perform this optimization if any insn:
2754 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2755 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2756 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2759 We also do not do this if we find an insn with ASM_OPERANDS. While
2760 this restriction should not be necessary, copying an insn with
2761 ASM_OPERANDS can confuse asm_noperands in some cases.
2763 Also, don't do this if the exit code is more than 20 insns. */
2765 for (insn = exitcode;
2767 && ! (GET_CODE (insn) == NOTE
2768 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2769 insn = NEXT_INSN (insn))
2771 switch (GET_CODE (insn))
2777 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2778 a jump immediately after the loop start that branches outside
2779 the loop but within an outer loop, near the exit test.
2780 If we copied this exit test and created a phony
2781 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2782 before the exit test look like these could be safely moved
2783 out of the loop even if they actually may be never executed.
2784 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2786 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2787 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2791 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2792 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
2793 /* If we were to duplicate this code, we would not move
2794 the BLOCK notes, and so debugging the moved code would
2795 be difficult. Thus, we only move the code with -O2 or
2802 /* The code below would grossly mishandle REG_WAS_0 notes,
2803 so get rid of them here. */
2804 while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
2805 remove_note (insn, p);
2806 if (++num_insns > 20
2807 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2808 || find_reg_note (insn, REG_LIBCALL, NULL_RTX)
2809 || asm_noperands (PATTERN (insn)) > 0)
2817 /* Unless INSN is zero, we can do the optimization. */
2823 /* See if any insn sets a register only used in the loop exit code and
2824 not a user variable. If so, replace it with a new register. */
2825 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2826 if (GET_CODE (insn) == INSN
2827 && (set = single_set (insn)) != 0
2828 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2829 || (GET_CODE (reg) == SUBREG
2830 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2831 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2832 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2834 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2835 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2840 /* We can do the replacement. Allocate reg_map if this is the
2841 first replacement we found. */
2844 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2845 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2848 REG_LOOP_TEST_P (reg) = 1;
2850 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2854 /* Now copy each insn. */
2855 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2857 switch (GET_CODE (insn))
2860 copy = emit_barrier_before (loop_start);
2863 /* Only copy line-number notes. */
2864 if (NOTE_LINE_NUMBER (insn) >= 0)
2866 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2867 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2872 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2874 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2876 mark_jump_label (PATTERN (copy), copy, 0);
2878 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2880 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2881 if (REG_NOTE_KIND (link) != REG_LABEL)
2883 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2886 if (reg_map && REG_NOTES (copy))
2887 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2891 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2893 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2894 mark_jump_label (PATTERN (copy), copy, 0);
2895 if (REG_NOTES (insn))
2897 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2899 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2902 /* If this is a simple jump, add it to the jump chain. */
2904 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2905 && simplejump_p (copy))
2907 jump_chain[INSN_UID (copy)]
2908 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2909 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2917 /* Record the first insn we copied. We need it so that we can
2918 scan the copied insns for new pseudo registers. */
2923 /* Now clean up by emitting a jump to the end label and deleting the jump
2924 at the start of the loop. */
2925 if (! copy || GET_CODE (copy) != BARRIER)
2927 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2930 /* Record the first insn we copied. We need it so that we can
2931 scan the copied insns for new pseudo registers. This may not
2932 be strictly necessary since we should have copied at least one
2933 insn above. But I am going to be safe. */
2937 mark_jump_label (PATTERN (copy), copy, 0);
2938 if (INSN_UID (copy) < max_jump_chain
2939 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2941 jump_chain[INSN_UID (copy)]
2942 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2943 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2945 emit_barrier_before (loop_start);
2948 /* Now scan from the first insn we copied to the last insn we copied
2949 (copy) for new pseudo registers. Do this after the code to jump to
2950 the end label since that might create a new pseudo too. */
2951 reg_scan_update (first_copy, copy, max_reg);
2953 /* Mark the exit code as the virtual top of the converted loop. */
2954 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2956 delete_insn (next_nonnote_insn (loop_start));
2961 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2962 loop-end notes between START and END out before START. Assume that
2963 END is not such a note. START may be such a note. Returns the value
2964 of the new starting insn, which may be different if the original start
2968 squeeze_notes (start, end)
2974 for (insn = start; insn != end; insn = next)
2976 next = NEXT_INSN (insn);
2977 if (GET_CODE (insn) == NOTE
2978 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2979 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2980 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2981 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2982 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2983 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2989 rtx prev = PREV_INSN (insn);
2990 PREV_INSN (insn) = PREV_INSN (start);
2991 NEXT_INSN (insn) = start;
2992 NEXT_INSN (PREV_INSN (insn)) = insn;
2993 PREV_INSN (NEXT_INSN (insn)) = insn;
2994 NEXT_INSN (prev) = next;
2995 PREV_INSN (next) = prev;
3003 /* Compare the instructions before insn E1 with those before E2
3004 to find an opportunity for cross jumping.
3005 (This means detecting identical sequences of insns followed by
3006 jumps to the same place, or followed by a label and a jump
3007 to that label, and replacing one with a jump to the other.)
3009 Assume E1 is a jump that jumps to label E2
3010 (that is not always true but it might as well be).
3011 Find the longest possible equivalent sequences
3012 and store the first insns of those sequences into *F1 and *F2.
3013 Store zero there if no equivalent preceding instructions are found.
3015 We give up if we find a label in stream 1.
3016 Actually we could transfer that label into stream 2. */
3019 find_cross_jump (e1, e2, minimum, f1, f2)
3024 register rtx i1 = e1, i2 = e2;
3025 register rtx p1, p2;
3028 rtx last1 = 0, last2 = 0;
3029 rtx afterlast1 = 0, afterlast2 = 0;
3036 i1 = prev_nonnote_insn (i1);
3038 i2 = PREV_INSN (i2);
3039 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
3040 i2 = PREV_INSN (i2);
3045 /* Don't allow the range of insns preceding E1 or E2
3046 to include the other (E2 or E1). */
3047 if (i2 == e1 || i1 == e2)
3050 /* If we will get to this code by jumping, those jumps will be
3051 tensioned to go directly to the new label (before I2),
3052 so this cross-jumping won't cost extra. So reduce the minimum. */
3053 if (GET_CODE (i1) == CODE_LABEL)
3059 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
3062 /* Avoid moving insns across EH regions if either of the insns
3065 && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
3066 && !in_same_eh_region (i1, i2))
3072 /* If this is a CALL_INSN, compare register usage information.
3073 If we don't check this on stack register machines, the two
3074 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3075 numbers of stack registers in the same basic block.
3076 If we don't check this on machines with delay slots, a delay slot may
3077 be filled that clobbers a parameter expected by the subroutine.
3079 ??? We take the simple route for now and assume that if they're
3080 equal, they were constructed identically. */
3082 if (GET_CODE (i1) == CALL_INSN
3083 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
3084 CALL_INSN_FUNCTION_USAGE (i2)))
3088 /* If cross_jump_death_matters is not 0, the insn's mode
3089 indicates whether or not the insn contains any stack-like
3092 if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
3094 /* If register stack conversion has already been done, then
3095 death notes must also be compared before it is certain that
3096 the two instruction streams match. */
3099 HARD_REG_SET i1_regset, i2_regset;
3101 CLEAR_HARD_REG_SET (i1_regset);
3102 CLEAR_HARD_REG_SET (i2_regset);
3104 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
3105 if (REG_NOTE_KIND (note) == REG_DEAD
3106 && STACK_REG_P (XEXP (note, 0)))
3107 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
3109 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
3110 if (REG_NOTE_KIND (note) == REG_DEAD
3111 && STACK_REG_P (XEXP (note, 0)))
3112 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
3114 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
3123 /* Don't allow old-style asm or volatile extended asms to be accepted
3124 for cross jumping purposes. It is conceptually correct to allow
3125 them, since cross-jumping preserves the dynamic instruction order
3126 even though it is changing the static instruction order. However,
3127 if an asm is being used to emit an assembler pseudo-op, such as
3128 the MIPS `.set reorder' pseudo-op, then the static instruction order
3129 matters and it must be preserved. */
3130 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
3131 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
3132 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
3135 if (lose || GET_CODE (p1) != GET_CODE (p2)
3136 || ! rtx_renumbered_equal_p (p1, p2))
3138 /* The following code helps take care of G++ cleanups. */
3142 if (!lose && GET_CODE (p1) == GET_CODE (p2)
3143 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
3144 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
3145 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
3146 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
3147 /* If the equivalences are not to a constant, they may
3148 reference pseudos that no longer exist, so we can't
3150 && CONSTANT_P (XEXP (equiv1, 0))
3151 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
3153 rtx s1 = single_set (i1);
3154 rtx s2 = single_set (i2);
3155 if (s1 != 0 && s2 != 0
3156 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
3158 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
3159 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
3160 if (! rtx_renumbered_equal_p (p1, p2))
3162 else if (apply_change_group ())
3167 /* Insns fail to match; cross jumping is limited to the following
3171 /* Don't allow the insn after a compare to be shared by
3172 cross-jumping unless the compare is also shared.
3173 Here, if either of these non-matching insns is a compare,
3174 exclude the following insn from possible cross-jumping. */
3175 if (sets_cc0_p (p1) || sets_cc0_p (p2))
3176 last1 = afterlast1, last2 = afterlast2, ++minimum;
3179 /* If cross-jumping here will feed a jump-around-jump
3180 optimization, this jump won't cost extra, so reduce
3182 if (GET_CODE (i1) == JUMP_INSN
3184 && prev_real_insn (JUMP_LABEL (i1)) == e1)
3190 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
3192 /* Ok, this insn is potentially includable in a cross-jump here. */
3193 afterlast1 = last1, afterlast2 = last2;
3194 last1 = i1, last2 = i2, --minimum;
3198 if (minimum <= 0 && last1 != 0 && last1 != e1)
3199 *f1 = last1, *f2 = last2;
3203 do_cross_jump (insn, newjpos, newlpos)
3204 rtx insn, newjpos, newlpos;
3206 /* Find an existing label at this point
3207 or make a new one if there is none. */
3208 register rtx label = get_label_before (newlpos);
3210 /* Make the same jump insn jump to the new point. */
3211 if (GET_CODE (PATTERN (insn)) == RETURN)
3213 /* Remove from jump chain of returns. */
3214 delete_from_jump_chain (insn);
3215 /* Change the insn. */
3216 PATTERN (insn) = gen_jump (label);
3217 INSN_CODE (insn) = -1;
3218 JUMP_LABEL (insn) = label;
3219 LABEL_NUSES (label)++;
3220 /* Add to new the jump chain. */
3221 if (INSN_UID (label) < max_jump_chain
3222 && INSN_UID (insn) < max_jump_chain)
3224 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
3225 jump_chain[INSN_UID (label)] = insn;
3229 redirect_jump (insn, label);
3231 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
3232 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
3233 the NEWJPOS stream. */
3235 while (newjpos != insn)
3239 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
3240 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
3241 || REG_NOTE_KIND (lnote) == REG_EQUIV)
3242 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
3243 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
3244 remove_note (newlpos, lnote);
3246 delete_insn (newjpos);
3247 newjpos = next_real_insn (newjpos);
3248 newlpos = next_real_insn (newlpos);
3252 /* Return the label before INSN, or put a new label there. */
3255 get_label_before (insn)
3260 /* Find an existing label at this point
3261 or make a new one if there is none. */
3262 label = prev_nonnote_insn (insn);
3264 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3266 rtx prev = PREV_INSN (insn);
3268 label = gen_label_rtx ();
3269 emit_label_after (label, prev);
3270 LABEL_NUSES (label) = 0;
3275 /* Return the label after INSN, or put a new label there. */
3278 get_label_after (insn)
3283 /* Find an existing label at this point
3284 or make a new one if there is none. */
3285 label = next_nonnote_insn (insn);
3287 if (label == 0 || GET_CODE (label) != CODE_LABEL)
3289 label = gen_label_rtx ();
3290 emit_label_after (label, insn);
3291 LABEL_NUSES (label) = 0;
3296 /* Return 1 if INSN is a jump that jumps to right after TARGET
3297 only on the condition that TARGET itself would drop through.
3298 Assumes that TARGET is a conditional jump. */
3301 jump_back_p (insn, target)
3305 enum rtx_code codei, codet;
3307 if (simplejump_p (insn) || ! condjump_p (insn)
3308 || simplejump_p (target)
3309 || target != prev_real_insn (JUMP_LABEL (insn)))
3312 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
3313 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
3315 codei = GET_CODE (cinsn);
3316 codet = GET_CODE (ctarget);
3318 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
3320 if (! can_reverse_comparison_p (cinsn, insn))
3322 codei = reverse_condition (codei);
3325 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
3327 if (! can_reverse_comparison_p (ctarget, target))
3329 codet = reverse_condition (codet);
3332 return (codei == codet
3333 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
3334 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
3337 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
3338 return non-zero if it is safe to reverse this comparison. It is if our
3339 floating-point is not IEEE, if this is an NE or EQ comparison, or if
3340 this is known to be an integer comparison. */
3343 can_reverse_comparison_p (comparison, insn)
3349 /* If this is not actually a comparison, we can't reverse it. */
3350 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
3353 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3354 /* If this is an NE comparison, it is safe to reverse it to an EQ
3355 comparison and vice versa, even for floating point. If no operands
3356 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
3357 always false and NE is always true, so the reversal is also valid. */
3359 || GET_CODE (comparison) == NE
3360 || GET_CODE (comparison) == EQ)
3363 arg0 = XEXP (comparison, 0);
3365 /* Make sure ARG0 is one of the actual objects being compared. If we
3366 can't do this, we can't be sure the comparison can be reversed.
3368 Handle cc0 and a MODE_CC register. */
3369 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
3375 rtx prev = prev_nonnote_insn (insn);
3378 /* First see if the condition code mode alone if enough to say we can
3379 reverse the condition. If not, then search backwards for a set of
3380 ARG0. We do not need to check for an insn clobbering it since valid
3381 code will contain set a set with no intervening clobber. But
3382 stop when we reach a label. */
3383 #ifdef REVERSIBLE_CC_MODE
3384 if (GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC
3385 && REVERSIBLE_CC_MODE (GET_MODE (arg0)))
3389 for (prev = prev_nonnote_insn (insn);
3390 prev != 0 && GET_CODE (prev) != CODE_LABEL;
3391 prev = prev_nonnote_insn (prev))
3392 if ((set = single_set (prev)) != 0
3393 && rtx_equal_p (SET_DEST (set), arg0))
3395 arg0 = SET_SRC (set);
3397 if (GET_CODE (arg0) == COMPARE)
3398 arg0 = XEXP (arg0, 0);
3403 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
3404 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
3405 return (GET_CODE (arg0) == CONST_INT
3406 || (GET_MODE (arg0) != VOIDmode
3407 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
3408 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
3411 /* Given an rtx-code for a comparison, return the code
3412 for the negated comparison.
3413 WATCH OUT! reverse_condition is not safe to use on a jump
3414 that might be acting on the results of an IEEE floating point comparison,
3415 because of the special treatment of non-signaling nans in comparisons.
3416 Use can_reverse_comparison_p to be sure. */
3419 reverse_condition (code)
3460 /* Similar, but return the code when two operands of a comparison are swapped.
3461 This IS safe for IEEE floating-point. */
3464 swap_condition (code)
3503 /* Given a comparison CODE, return the corresponding unsigned comparison.
3504 If CODE is an equality comparison or already an unsigned comparison,
3505 CODE is returned. */
3508 unsigned_condition (code)
3538 /* Similarly, return the signed version of a comparison. */
3541 signed_condition (code)
3571 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3572 truth of CODE1 implies the truth of CODE2. */
3575 comparison_dominates_p (code1, code2)
3576 enum rtx_code code1, code2;
3584 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3589 if (code2 == LE || code2 == NE)
3594 if (code2 == GE || code2 == NE)
3599 if (code2 == LEU || code2 == NE)
3604 if (code2 == GEU || code2 == NE)
3615 /* Return 1 if INSN is an unconditional jump and nothing else. */
3621 return (GET_CODE (insn) == JUMP_INSN
3622 && GET_CODE (PATTERN (insn)) == SET
3623 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3624 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3627 /* Return nonzero if INSN is a (possibly) conditional jump
3628 and nothing more. */
3634 register rtx x = PATTERN (insn);
3636 if (GET_CODE (x) != SET
3637 || GET_CODE (SET_DEST (x)) != PC)
3641 if (GET_CODE (x) == LABEL_REF)
3643 else return (GET_CODE (x) == IF_THEN_ELSE
3644 && ((GET_CODE (XEXP (x, 2)) == PC
3645 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
3646 || GET_CODE (XEXP (x, 1)) == RETURN))
3647 || (GET_CODE (XEXP (x, 1)) == PC
3648 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
3649 || GET_CODE (XEXP (x, 2)) == RETURN))));
3654 /* Return nonzero if INSN is a (possibly) conditional jump inside a
3658 condjump_in_parallel_p (insn)
3661 register rtx x = PATTERN (insn);
3663 if (GET_CODE (x) != PARALLEL)
3666 x = XVECEXP (x, 0, 0);
3668 if (GET_CODE (x) != SET)
3670 if (GET_CODE (SET_DEST (x)) != PC)
3672 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3674 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3676 if (XEXP (SET_SRC (x), 2) == pc_rtx
3677 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3678 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3680 if (XEXP (SET_SRC (x), 1) == pc_rtx
3681 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3682 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3687 /* Return the label of a conditional jump. */
3690 condjump_label (insn)
3693 register rtx x = PATTERN (insn);
3695 if (GET_CODE (x) == PARALLEL)
3696 x = XVECEXP (x, 0, 0);
3697 if (GET_CODE (x) != SET)
3699 if (GET_CODE (SET_DEST (x)) != PC)
3702 if (GET_CODE (x) == LABEL_REF)
3704 if (GET_CODE (x) != IF_THEN_ELSE)
3706 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
3708 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
3713 /* Return true if INSN is a (possibly conditional) return insn. */
3716 returnjump_p_1 (loc, data)
3718 void *data ATTRIBUTE_UNUSED;
3721 return GET_CODE (x) == RETURN;
3728 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
3731 /* Return true if INSN is a jump that only transfers control and
3740 if (GET_CODE (insn) != JUMP_INSN)
3743 set = single_set (insn);
3746 if (GET_CODE (SET_DEST (set)) != PC)
3748 if (side_effects_p (SET_SRC (set)))
3756 /* Return 1 if X is an RTX that does nothing but set the condition codes
3757 and CLOBBER or USE registers.
3758 Return -1 if X does explicitly set the condition codes,
3759 but also does other things. */
3763 rtx x ATTRIBUTE_UNUSED;
3765 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3767 if (GET_CODE (x) == PARALLEL)
3771 int other_things = 0;
3772 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3774 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3775 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3777 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3780 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3786 /* Follow any unconditional jump at LABEL;
3787 return the ultimate label reached by any such chain of jumps.
3788 If LABEL is not followed by a jump, return LABEL.
3789 If the chain loops or we can't find end, return LABEL,
3790 since that tells caller to avoid changing the insn.
3792 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3793 a USE or CLOBBER. */
3796 follow_jumps (label)
3801 register rtx value = label;
3806 && (insn = next_active_insn (value)) != 0
3807 && GET_CODE (insn) == JUMP_INSN
3808 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3809 || GET_CODE (PATTERN (insn)) == RETURN)
3810 && (next = NEXT_INSN (insn))
3811 && GET_CODE (next) == BARRIER);
3814 /* Don't chain through the insn that jumps into a loop
3815 from outside the loop,
3816 since that would create multiple loop entry jumps
3817 and prevent loop optimization. */
3819 if (!reload_completed)
3820 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3821 if (GET_CODE (tem) == NOTE
3822 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3823 /* ??? Optional. Disables some optimizations, but makes
3824 gcov output more accurate with -O. */
3825 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3828 /* If we have found a cycle, make the insn jump to itself. */
3829 if (JUMP_LABEL (insn) == label)
3832 tem = next_active_insn (JUMP_LABEL (insn));
3833 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3834 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3837 value = JUMP_LABEL (insn);
3844 /* Assuming that field IDX of X is a vector of label_refs,
3845 replace each of them by the ultimate label reached by it.
3846 Return nonzero if a change is made.
3847 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3850 tension_vector_labels (x, idx)
3856 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3858 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3859 register rtx nlabel = follow_jumps (olabel);
3860 if (nlabel && nlabel != olabel)
3862 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3863 ++LABEL_NUSES (nlabel);
3864 if (--LABEL_NUSES (olabel) == 0)
3865 delete_insn (olabel);
3872 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3873 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3874 in INSN, then store one of them in JUMP_LABEL (INSN).
3875 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3876 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3877 Also, when there are consecutive labels, canonicalize on the last of them.
3879 Note that two labels separated by a loop-beginning note
3880 must be kept distinct if we have not yet done loop-optimization,
3881 because the gap between them is where loop-optimize
3882 will want to move invariant code to. CROSS_JUMP tells us
3883 that loop-optimization is done with.
3885 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3886 two labels distinct if they are separated by only USE or CLOBBER insns. */
3889 mark_jump_label (x, insn, cross_jump)
3894 register RTX_CODE code = GET_CODE (x);
3896 register const char *fmt;
3912 /* If this is a constant-pool reference, see if it is a label. */
3913 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3914 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3915 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3920 rtx label = XEXP (x, 0);
3925 if (GET_CODE (label) != CODE_LABEL)
3928 /* Ignore references to labels of containing functions. */
3929 if (LABEL_REF_NONLOCAL_P (x))
3932 /* If there are other labels following this one,
3933 replace it with the last of the consecutive labels. */
3934 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3936 if (GET_CODE (next) == CODE_LABEL)
3938 else if (cross_jump && GET_CODE (next) == INSN
3939 && (GET_CODE (PATTERN (next)) == USE
3940 || GET_CODE (PATTERN (next)) == CLOBBER))
3942 else if (GET_CODE (next) != NOTE)
3944 else if (! cross_jump
3945 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3946 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3947 /* ??? Optional. Disables some optimizations, but
3948 makes gcov output more accurate with -O. */
3949 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3953 XEXP (x, 0) = label;
3954 if (! insn || ! INSN_DELETED_P (insn))
3955 ++LABEL_NUSES (label);
3959 if (GET_CODE (insn) == JUMP_INSN)
3960 JUMP_LABEL (insn) = label;
3962 /* If we've changed OLABEL and we had a REG_LABEL note
3963 for it, update it as well. */
3964 else if (label != olabel
3965 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3966 XEXP (note, 0) = label;
3968 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3970 else if (! find_reg_note (insn, REG_LABEL, label))
3972 /* This code used to ignore labels which refered to dispatch
3973 tables to avoid flow.c generating worse code.
3975 However, in the presense of global optimizations like
3976 gcse which call find_basic_blocks without calling
3977 life_analysis, not recording such labels will lead
3978 to compiler aborts because of inconsistencies in the
3979 flow graph. So we go ahead and record the label.
3981 It may also be the case that the optimization argument
3982 is no longer valid because of the more accurate cfg
3983 we build in find_basic_blocks -- it no longer pessimizes
3984 code when it finds a REG_LABEL note. */
3985 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
3992 /* Do walk the labels in a vector, but not the first operand of an
3993 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3996 if (! INSN_DELETED_P (insn))
3998 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
4000 for (i = 0; i < XVECLEN (x, eltnum); i++)
4001 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
4009 fmt = GET_RTX_FORMAT (code);
4010 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4013 mark_jump_label (XEXP (x, i), insn, cross_jump);
4014 else if (fmt[i] == 'E')
4017 for (j = 0; j < XVECLEN (x, i); j++)
4018 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
4023 /* If all INSN does is set the pc, delete it,
4024 and delete the insn that set the condition codes for it
4025 if that's what the previous thing was. */
4031 register rtx set = single_set (insn);
4033 if (set && GET_CODE (SET_DEST (set)) == PC)
4034 delete_computation (insn);
4037 /* Recursively delete prior insns that compute the value (used only by INSN
4038 which the caller is deleting) stored in the register mentioned by NOTE
4039 which is a REG_DEAD note associated with INSN. */
4042 delete_prior_computation (note, insn)
4047 rtx reg = XEXP (note, 0);
4049 for (our_prev = prev_nonnote_insn (insn);
4050 our_prev && (GET_CODE (our_prev) == INSN
4051 || GET_CODE (our_prev) == CALL_INSN);
4052 our_prev = prev_nonnote_insn (our_prev))
4054 rtx pat = PATTERN (our_prev);
4056 /* If we reach a CALL which is not calling a const function
4057 or the callee pops the arguments, then give up. */
4058 if (GET_CODE (our_prev) == CALL_INSN
4059 && (! CONST_CALL_P (our_prev)
4060 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
4063 /* If we reach a SEQUENCE, it is too complex to try to
4064 do anything with it, so give up. */
4065 if (GET_CODE (pat) == SEQUENCE)
4068 if (GET_CODE (pat) == USE
4069 && GET_CODE (XEXP (pat, 0)) == INSN)
4070 /* reorg creates USEs that look like this. We leave them
4071 alone because reorg needs them for its own purposes. */
4074 if (reg_set_p (reg, pat))
4076 if (side_effects_p (pat) && GET_CODE (our_prev) != CALL_INSN)
4079 if (GET_CODE (pat) == PARALLEL)
4081 /* If we find a SET of something else, we can't
4086 for (i = 0; i < XVECLEN (pat, 0); i++)
4088 rtx part = XVECEXP (pat, 0, i);
4090 if (GET_CODE (part) == SET
4091 && SET_DEST (part) != reg)
4095 if (i == XVECLEN (pat, 0))
4096 delete_computation (our_prev);
4098 else if (GET_CODE (pat) == SET
4099 && GET_CODE (SET_DEST (pat)) == REG)
4101 int dest_regno = REGNO (SET_DEST (pat));
4103 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
4104 ? HARD_REGNO_NREGS (dest_regno,
4105 GET_MODE (SET_DEST (pat))) : 1);
4106 int regno = REGNO (reg);
4107 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
4108 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
4110 if (dest_regno >= regno
4111 && dest_endregno <= endregno)
4112 delete_computation (our_prev);
4114 /* We may have a multi-word hard register and some, but not
4115 all, of the words of the register are needed in subsequent
4116 insns. Write REG_UNUSED notes for those parts that were not
4118 else if (dest_regno <= regno
4119 && dest_endregno >= endregno)
4123 REG_NOTES (our_prev)
4124 = gen_rtx_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (our_prev));
4126 for (i = dest_regno; i < dest_endregno; i++)
4127 if (! find_regno_note (our_prev, REG_UNUSED, i))
4130 if (i == dest_endregno)
4131 delete_computation (our_prev);
4138 /* If PAT references the register that dies here, it is an
4139 additional use. Hence any prior SET isn't dead. However, this
4140 insn becomes the new place for the REG_DEAD note. */
4141 if (reg_overlap_mentioned_p (reg, pat))
4143 XEXP (note, 1) = REG_NOTES (our_prev);
4144 REG_NOTES (our_prev) = note;
4150 /* Delete INSN and recursively delete insns that compute values used only
4151 by INSN. This uses the REG_DEAD notes computed during flow analysis.
4152 If we are running before flow.c, we need do nothing since flow.c will
4153 delete dead code. We also can't know if the registers being used are
4154 dead or not at this point.
4156 Otherwise, look at all our REG_DEAD notes. If a previous insn does
4157 nothing other than set a register that dies in this insn, we can delete
4160 On machines with CC0, if CC0 is used in this insn, we may be able to
4161 delete the insn that set it. */
4164 delete_computation (insn)
4171 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
4173 rtx prev = prev_nonnote_insn (insn);
4174 /* We assume that at this stage
4175 CC's are always set explicitly
4176 and always immediately before the jump that
4177 will use them. So if the previous insn
4178 exists to set the CC's, delete it
4179 (unless it performs auto-increments, etc.). */
4180 if (prev && GET_CODE (prev) == INSN
4181 && sets_cc0_p (PATTERN (prev)))
4183 if (sets_cc0_p (PATTERN (prev)) > 0
4184 && ! side_effects_p (PATTERN (prev)))
4185 delete_computation (prev);
4187 /* Otherwise, show that cc0 won't be used. */
4188 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
4189 cc0_rtx, REG_NOTES (prev));
4194 #ifdef INSN_SCHEDULING
4195 /* ?!? The schedulers do not keep REG_DEAD notes accurate after
4196 reload has completed. The schedulers need to be fixed. Until
4197 they are, we must not rely on the death notes here. */
4198 if (reload_completed && flag_schedule_insns_after_reload)
4205 /* The REG_DEAD note may have been omitted for a register
4206 which is both set and used by the insn. */
4207 set = single_set (insn);
4208 if (set && GET_CODE (SET_DEST (set)) == REG)
4210 int dest_regno = REGNO (SET_DEST (set));
4212 = dest_regno + (dest_regno < FIRST_PSEUDO_REGISTER
4213 ? HARD_REGNO_NREGS (dest_regno,
4214 GET_MODE (SET_DEST (set))) : 1);
4217 for (i = dest_regno; i < dest_endregno; i++)
4219 if (! refers_to_regno_p (i, i + 1, SET_SRC (set), NULL_PTR)
4220 || find_regno_note (insn, REG_DEAD, i))
4223 note = gen_rtx_EXPR_LIST (REG_DEAD, (i < FIRST_PSEUDO_REGISTER
4224 ? gen_rtx_REG (reg_raw_mode[i], i)
4225 : SET_DEST (set)), NULL_RTX);
4226 delete_prior_computation (note, insn);
4230 for (note = REG_NOTES (insn); note; note = next)
4232 next = XEXP (note, 1);
4234 if (REG_NOTE_KIND (note) != REG_DEAD
4235 /* Verify that the REG_NOTE is legitimate. */
4236 || GET_CODE (XEXP (note, 0)) != REG)
4239 delete_prior_computation (note, insn);
4245 /* Delete insn INSN from the chain of insns and update label ref counts.
4246 May delete some following insns as a consequence; may even delete
4247 a label elsewhere and insns that follow it.
4249 Returns the first insn after INSN that was not deleted. */
4255 register rtx next = NEXT_INSN (insn);
4256 register rtx prev = PREV_INSN (insn);
4257 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
4258 register int dont_really_delete = 0;
4260 while (next && INSN_DELETED_P (next))
4261 next = NEXT_INSN (next);
4263 /* This insn is already deleted => return first following nondeleted. */
4264 if (INSN_DELETED_P (insn))
4268 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
4270 /* Don't delete user-declared labels. Convert them to special NOTEs
4272 if (was_code_label && LABEL_NAME (insn) != 0
4273 && optimize && ! dont_really_delete)
4275 PUT_CODE (insn, NOTE);
4276 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
4277 NOTE_SOURCE_FILE (insn) = 0;
4278 dont_really_delete = 1;
4281 /* Mark this insn as deleted. */
4282 INSN_DELETED_P (insn) = 1;
4284 /* If this is an unconditional jump, delete it from the jump chain. */
4285 if (simplejump_p (insn))
4286 delete_from_jump_chain (insn);
4288 /* If instruction is followed by a barrier,
4289 delete the barrier too. */
4291 if (next != 0 && GET_CODE (next) == BARRIER)
4293 INSN_DELETED_P (next) = 1;
4294 next = NEXT_INSN (next);
4297 /* Patch out INSN (and the barrier if any) */
4299 if (optimize && ! dont_really_delete)
4303 NEXT_INSN (prev) = next;
4304 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
4305 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
4306 XVECLEN (PATTERN (prev), 0) - 1)) = next;
4311 PREV_INSN (next) = prev;
4312 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
4313 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
4316 if (prev && NEXT_INSN (prev) == 0)
4317 set_last_insn (prev);
4320 /* If deleting a jump, decrement the count of the label,
4321 and delete the label if it is now unused. */
4323 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
4325 rtx lab = JUMP_LABEL (insn), lab_next;
4327 if (--LABEL_NUSES (lab) == 0)
4329 /* This can delete NEXT or PREV,
4330 either directly if NEXT is JUMP_LABEL (INSN),
4331 or indirectly through more levels of jumps. */
4334 /* I feel a little doubtful about this loop,
4335 but I see no clean and sure alternative way
4336 to find the first insn after INSN that is not now deleted.
4337 I hope this works. */
4338 while (next && INSN_DELETED_P (next))
4339 next = NEXT_INSN (next);
4342 else if ((lab_next = next_nonnote_insn (lab)) != NULL
4343 && GET_CODE (lab_next) == JUMP_INSN
4344 && (GET_CODE (PATTERN (lab_next)) == ADDR_VEC
4345 || GET_CODE (PATTERN (lab_next)) == ADDR_DIFF_VEC))
4347 /* If we're deleting the tablejump, delete the dispatch table.
4348 We may not be able to kill the label immediately preceeding
4349 just yet, as it might be referenced in code leading up to
4351 delete_insn (lab_next);
4355 /* Likewise if we're deleting a dispatch table. */
4357 if (GET_CODE (insn) == JUMP_INSN
4358 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
4359 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
4361 rtx pat = PATTERN (insn);
4362 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
4363 int len = XVECLEN (pat, diff_vec_p);
4365 for (i = 0; i < len; i++)
4366 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
4367 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
4368 while (next && INSN_DELETED_P (next))
4369 next = NEXT_INSN (next);
4373 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
4374 prev = PREV_INSN (prev);
4376 /* If INSN was a label and a dispatch table follows it,
4377 delete the dispatch table. The tablejump must have gone already.
4378 It isn't useful to fall through into a table. */
4381 && NEXT_INSN (insn) != 0
4382 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
4383 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
4384 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
4385 next = delete_insn (NEXT_INSN (insn));
4387 /* If INSN was a label, delete insns following it if now unreachable. */
4389 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
4391 register RTX_CODE code;
4393 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
4394 || code == NOTE || code == BARRIER
4395 || (code == CODE_LABEL && INSN_DELETED_P (next))))
4398 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
4399 next = NEXT_INSN (next);
4400 /* Keep going past other deleted labels to delete what follows. */
4401 else if (code == CODE_LABEL && INSN_DELETED_P (next))
4402 next = NEXT_INSN (next);
4404 /* Note: if this deletes a jump, it can cause more
4405 deletion of unreachable code, after a different label.
4406 As long as the value from this recursive call is correct,
4407 this invocation functions correctly. */
4408 next = delete_insn (next);
4415 /* Advance from INSN till reaching something not deleted
4416 then return that. May return INSN itself. */
4419 next_nondeleted_insn (insn)
4422 while (INSN_DELETED_P (insn))
4423 insn = NEXT_INSN (insn);
4427 /* Delete a range of insns from FROM to TO, inclusive.
4428 This is for the sake of peephole optimization, so assume
4429 that whatever these insns do will still be done by a new
4430 peephole insn that will replace them. */
4433 delete_for_peephole (from, to)
4434 register rtx from, to;
4436 register rtx insn = from;
4440 register rtx next = NEXT_INSN (insn);
4441 register rtx prev = PREV_INSN (insn);
4443 if (GET_CODE (insn) != NOTE)
4445 INSN_DELETED_P (insn) = 1;
4447 /* Patch this insn out of the chain. */
4448 /* We don't do this all at once, because we
4449 must preserve all NOTEs. */
4451 NEXT_INSN (prev) = next;
4454 PREV_INSN (next) = prev;
4462 /* Note that if TO is an unconditional jump
4463 we *do not* delete the BARRIER that follows,
4464 since the peephole that replaces this sequence
4465 is also an unconditional jump in that case. */
4468 /* We have determined that INSN is never reached, and are about to
4469 delete it. Print a warning if the user asked for one.
4471 To try to make this warning more useful, this should only be called
4472 once per basic block not reached, and it only warns when the basic
4473 block contains more than one line from the current function, and
4474 contains at least one operation. CSE and inlining can duplicate insns,
4475 so it's possible to get spurious warnings from this. */
4478 never_reached_warning (avoided_insn)
4482 rtx a_line_note = NULL;
4483 int two_avoided_lines = 0;
4484 int contains_insn = 0;
4486 if (! warn_notreached)
4489 /* Scan forwards, looking at LINE_NUMBER notes, until
4490 we hit a LABEL or we run out of insns. */
4492 for (insn = avoided_insn; insn != NULL; insn = NEXT_INSN (insn))
4494 if (GET_CODE (insn) == CODE_LABEL)
4496 else if (GET_CODE (insn) == NOTE /* A line number note? */
4497 && NOTE_LINE_NUMBER (insn) >= 0)
4499 if (a_line_note == NULL)
4502 two_avoided_lines |= (NOTE_LINE_NUMBER (a_line_note)
4503 != NOTE_LINE_NUMBER (insn));
4505 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
4508 if (two_avoided_lines && contains_insn)
4509 warning_with_file_and_line (NOTE_SOURCE_FILE (a_line_note),
4510 NOTE_LINE_NUMBER (a_line_note),
4511 "will never be executed");
4514 /* Invert the condition of the jump JUMP, and make it jump
4515 to label NLABEL instead of where it jumps now. */
4518 invert_jump (jump, nlabel)
4521 /* We have to either invert the condition and change the label or
4522 do neither. Either operation could fail. We first try to invert
4523 the jump. If that succeeds, we try changing the label. If that fails,
4524 we invert the jump back to what it was. */
4526 if (! invert_exp (PATTERN (jump), jump))
4529 if (redirect_jump (jump, nlabel))
4531 if (flag_branch_probabilities)
4533 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
4535 /* An inverted jump means that a probability taken becomes a
4536 probability not taken. Subtract the branch probability from the
4537 probability base to convert it back to a taken probability.
4538 (We don't flip the probability on a branch that's never taken. */
4539 if (note && XINT (XEXP (note, 0), 0) >= 0)
4540 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
4546 if (! invert_exp (PATTERN (jump), jump))
4547 /* This should just be putting it back the way it was. */
4553 /* Invert the jump condition of rtx X contained in jump insn, INSN.
4555 Return 1 if we can do so, 0 if we cannot find a way to do so that
4556 matches a pattern. */
4559 invert_exp (x, insn)
4563 register RTX_CODE code;
4565 register const char *fmt;
4567 code = GET_CODE (x);
4569 if (code == IF_THEN_ELSE)
4571 register rtx comp = XEXP (x, 0);
4574 /* We can do this in two ways: The preferable way, which can only
4575 be done if this is not an integer comparison, is to reverse
4576 the comparison code. Otherwise, swap the THEN-part and ELSE-part
4577 of the IF_THEN_ELSE. If we can't do either, fail. */
4579 if (can_reverse_comparison_p (comp, insn)
4580 && validate_change (insn, &XEXP (x, 0),
4581 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
4582 GET_MODE (comp), XEXP (comp, 0),
4583 XEXP (comp, 1)), 0))
4587 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
4588 validate_change (insn, &XEXP (x, 2), tem, 1);
4589 return apply_change_group ();
4592 fmt = GET_RTX_FORMAT (code);
4593 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4596 if (! invert_exp (XEXP (x, i), insn))
4601 for (j = 0; j < XVECLEN (x, i); j++)
4602 if (!invert_exp (XVECEXP (x, i, j), insn))
4610 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
4611 If the old jump target label is unused as a result,
4612 it and the code following it may be deleted.
4614 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
4617 The return value will be 1 if the change was made, 0 if it wasn't (this
4618 can only occur for NLABEL == 0). */
4621 redirect_jump (jump, nlabel)
4624 register rtx olabel = JUMP_LABEL (jump);
4626 if (nlabel == olabel)
4629 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
4632 /* If this is an unconditional branch, delete it from the jump_chain of
4633 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
4634 have UID's in range and JUMP_CHAIN is valid). */
4635 if (jump_chain && (simplejump_p (jump)
4636 || GET_CODE (PATTERN (jump)) == RETURN))
4638 int label_index = nlabel ? INSN_UID (nlabel) : 0;
4640 delete_from_jump_chain (jump);
4641 if (label_index < max_jump_chain
4642 && INSN_UID (jump) < max_jump_chain)
4644 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
4645 jump_chain[label_index] = jump;
4649 JUMP_LABEL (jump) = nlabel;
4651 ++LABEL_NUSES (nlabel);
4653 if (olabel && --LABEL_NUSES (olabel) == 0)
4654 delete_insn (olabel);
4659 /* Delete the instruction JUMP from any jump chain it might be on. */
4662 delete_from_jump_chain (jump)
4666 rtx olabel = JUMP_LABEL (jump);
4668 /* Handle unconditional jumps. */
4669 if (jump_chain && olabel != 0
4670 && INSN_UID (olabel) < max_jump_chain
4671 && simplejump_p (jump))
4672 index = INSN_UID (olabel);
4673 /* Handle return insns. */
4674 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
4678 if (jump_chain[index] == jump)
4679 jump_chain[index] = jump_chain[INSN_UID (jump)];
4684 for (insn = jump_chain[index];
4686 insn = jump_chain[INSN_UID (insn)])
4687 if (jump_chain[INSN_UID (insn)] == jump)
4689 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
4695 /* If NLABEL is nonzero, throughout the rtx at LOC,
4696 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
4697 zero, alter (RETURN) to (LABEL_REF NLABEL).
4699 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
4700 validity with validate_change. Convert (set (pc) (label_ref olabel))
4703 Return 0 if we found a change we would like to make but it is invalid.
4704 Otherwise, return 1. */
4707 redirect_exp (loc, olabel, nlabel, insn)
4712 register rtx x = *loc;
4713 register RTX_CODE code = GET_CODE (x);
4715 register const char *fmt;
4717 if (code == LABEL_REF)
4719 if (XEXP (x, 0) == olabel)
4722 XEXP (x, 0) = nlabel;
4724 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4728 else if (code == RETURN && olabel == 0)
4730 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4731 if (loc == &PATTERN (insn))
4732 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4733 return validate_change (insn, loc, x, 0);
4736 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4737 && GET_CODE (SET_SRC (x)) == LABEL_REF
4738 && XEXP (SET_SRC (x), 0) == olabel)
4739 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4741 fmt = GET_RTX_FORMAT (code);
4742 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4745 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4750 for (j = 0; j < XVECLEN (x, i); j++)
4751 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4759 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4761 If the old jump target label (before the dispatch table) becomes unused,
4762 it and the dispatch table may be deleted. In that case, find the insn
4763 before the jump references that label and delete it and logical successors
4767 redirect_tablejump (jump, nlabel)
4770 register rtx olabel = JUMP_LABEL (jump);
4772 /* Add this jump to the jump_chain of NLABEL. */
4773 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4774 && INSN_UID (jump) < max_jump_chain)
4776 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4777 jump_chain[INSN_UID (nlabel)] = jump;
4780 PATTERN (jump) = gen_jump (nlabel);
4781 JUMP_LABEL (jump) = nlabel;
4782 ++LABEL_NUSES (nlabel);
4783 INSN_CODE (jump) = -1;
4785 if (--LABEL_NUSES (olabel) == 0)
4787 delete_labelref_insn (jump, olabel, 0);
4788 delete_insn (olabel);
4792 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4793 If we found one, delete it and then delete this insn if DELETE_THIS is
4794 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4797 delete_labelref_insn (insn, label, delete_this)
4804 if (GET_CODE (insn) != NOTE
4805 && reg_mentioned_p (label, PATTERN (insn)))
4816 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4817 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4831 /* Like rtx_equal_p except that it considers two REGs as equal
4832 if they renumber to the same value and considers two commutative
4833 operations to be the same if the order of the operands has been
4836 ??? Addition is not commutative on the PA due to the weird implicit
4837 space register selection rules for memory addresses. Therefore, we
4838 don't consider a + b == b + a.
4840 We could/should make this test a little tighter. Possibly only
4841 disabling it on the PA via some backend macro or only disabling this
4842 case when the PLUS is inside a MEM. */
4845 rtx_renumbered_equal_p (x, y)
4849 register RTX_CODE code = GET_CODE (x);
4850 register const char *fmt;
4855 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4856 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4857 && GET_CODE (SUBREG_REG (y)) == REG)))
4859 int reg_x = -1, reg_y = -1;
4860 int word_x = 0, word_y = 0;
4862 if (GET_MODE (x) != GET_MODE (y))
4865 /* If we haven't done any renumbering, don't
4866 make any assumptions. */
4867 if (reg_renumber == 0)
4868 return rtx_equal_p (x, y);
4872 reg_x = REGNO (SUBREG_REG (x));
4873 word_x = SUBREG_WORD (x);
4875 if (reg_renumber[reg_x] >= 0)
4877 reg_x = reg_renumber[reg_x] + word_x;
4885 if (reg_renumber[reg_x] >= 0)
4886 reg_x = reg_renumber[reg_x];
4889 if (GET_CODE (y) == SUBREG)
4891 reg_y = REGNO (SUBREG_REG (y));
4892 word_y = SUBREG_WORD (y);
4894 if (reg_renumber[reg_y] >= 0)
4896 reg_y = reg_renumber[reg_y];
4904 if (reg_renumber[reg_y] >= 0)
4905 reg_y = reg_renumber[reg_y];
4908 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4911 /* Now we have disposed of all the cases
4912 in which different rtx codes can match. */
4913 if (code != GET_CODE (y))
4925 return INTVAL (x) == INTVAL (y);
4928 /* We can't assume nonlocal labels have their following insns yet. */
4929 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4930 return XEXP (x, 0) == XEXP (y, 0);
4932 /* Two label-refs are equivalent if they point at labels
4933 in the same position in the instruction stream. */
4934 return (next_real_insn (XEXP (x, 0))
4935 == next_real_insn (XEXP (y, 0)));
4938 return XSTR (x, 0) == XSTR (y, 0);
4941 /* If we didn't match EQ equality above, they aren't the same. */
4948 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4950 if (GET_MODE (x) != GET_MODE (y))
4953 /* For commutative operations, the RTX match if the operand match in any
4954 order. Also handle the simple binary and unary cases without a loop.
4956 ??? Don't consider PLUS a commutative operator; see comments above. */
4957 if ((code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4959 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4960 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4961 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4962 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4963 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4964 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4965 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4966 else if (GET_RTX_CLASS (code) == '1')
4967 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4969 /* Compare the elements. If any pair of corresponding elements
4970 fail to match, return 0 for the whole things. */
4972 fmt = GET_RTX_FORMAT (code);
4973 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4979 if (XWINT (x, i) != XWINT (y, i))
4984 if (XINT (x, i) != XINT (y, i))
4989 if (strcmp (XSTR (x, i), XSTR (y, i)))
4994 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4999 if (XEXP (x, i) != XEXP (y, i))
5006 if (XVECLEN (x, i) != XVECLEN (y, i))
5008 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5009 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
5020 /* If X is a hard register or equivalent to one or a subregister of one,
5021 return the hard register number. If X is a pseudo register that was not
5022 assigned a hard register, return the pseudo register number. Otherwise,
5023 return -1. Any rtx is valid for X. */
5029 if (GET_CODE (x) == REG)
5031 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
5032 return reg_renumber[REGNO (x)];
5035 if (GET_CODE (x) == SUBREG)
5037 int base = true_regnum (SUBREG_REG (x));
5038 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
5039 return SUBREG_WORD (x) + base;
5044 /* Optimize code of the form:
5046 for (x = a[i]; x; ...)
5048 for (x = a[i]; x; ...)
5052 Loop optimize will change the above code into
5056 { ...; if (! (x = ...)) break; }
5059 { ...; if (! (x = ...)) break; }
5062 In general, if the first test fails, the program can branch
5063 directly to `foo' and skip the second try which is doomed to fail.
5064 We run this after loop optimization and before flow analysis. */
5066 /* When comparing the insn patterns, we track the fact that different
5067 pseudo-register numbers may have been used in each computation.
5068 The following array stores an equivalence -- same_regs[I] == J means
5069 that pseudo register I was used in the first set of tests in a context
5070 where J was used in the second set. We also count the number of such
5071 pending equivalences. If nonzero, the expressions really aren't the
5074 static int *same_regs;
5076 static int num_same_regs;
5078 /* Track any registers modified between the target of the first jump and
5079 the second jump. They never compare equal. */
5081 static char *modified_regs;
5083 /* Record if memory was modified. */
5085 static int modified_mem;
5087 /* Called via note_stores on each insn between the target of the first
5088 branch and the second branch. It marks any changed registers. */
5091 mark_modified_reg (dest, x)
5093 rtx x ATTRIBUTE_UNUSED;
5097 if (GET_CODE (dest) == SUBREG)
5098 dest = SUBREG_REG (dest);
5100 if (GET_CODE (dest) == MEM)
5103 if (GET_CODE (dest) != REG)
5106 regno = REGNO (dest);
5107 if (regno >= FIRST_PSEUDO_REGISTER)
5108 modified_regs[regno] = 1;
5110 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
5111 modified_regs[regno + i] = 1;
5114 /* F is the first insn in the chain of insns. */
5117 thread_jumps (f, max_reg, flag_before_loop)
5120 int flag_before_loop;
5122 /* Basic algorithm is to find a conditional branch,
5123 the label it may branch to, and the branch after
5124 that label. If the two branches test the same condition,
5125 walk back from both branch paths until the insn patterns
5126 differ, or code labels are hit. If we make it back to
5127 the target of the first branch, then we know that the first branch
5128 will either always succeed or always fail depending on the relative
5129 senses of the two branches. So adjust the first branch accordingly
5132 rtx label, b1, b2, t1, t2;
5133 enum rtx_code code1, code2;
5134 rtx b1op0, b1op1, b2op0, b2op1;
5139 /* Allocate register tables and quick-reset table. */
5140 modified_regs = (char *) alloca (max_reg * sizeof (char));
5141 same_regs = (int *) alloca (max_reg * sizeof (int));
5142 all_reset = (int *) alloca (max_reg * sizeof (int));
5143 for (i = 0; i < max_reg; i++)
5150 for (b1 = f; b1; b1 = NEXT_INSN (b1))
5152 /* Get to a candidate branch insn. */
5153 if (GET_CODE (b1) != JUMP_INSN
5154 || ! condjump_p (b1) || simplejump_p (b1)
5155 || JUMP_LABEL (b1) == 0)
5158 bzero (modified_regs, max_reg * sizeof (char));
5161 bcopy ((char *) all_reset, (char *) same_regs,
5162 max_reg * sizeof (int));
5165 label = JUMP_LABEL (b1);
5167 /* Look for a branch after the target. Record any registers and
5168 memory modified between the target and the branch. Stop when we
5169 get to a label since we can't know what was changed there. */
5170 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
5172 if (GET_CODE (b2) == CODE_LABEL)
5175 else if (GET_CODE (b2) == JUMP_INSN)
5177 /* If this is an unconditional jump and is the only use of
5178 its target label, we can follow it. */
5179 if (simplejump_p (b2)
5180 && JUMP_LABEL (b2) != 0
5181 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
5183 b2 = JUMP_LABEL (b2);
5190 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
5193 if (GET_CODE (b2) == CALL_INSN)
5196 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5197 if (call_used_regs[i] && ! fixed_regs[i]
5198 && i != STACK_POINTER_REGNUM
5199 && i != FRAME_POINTER_REGNUM
5200 && i != HARD_FRAME_POINTER_REGNUM
5201 && i != ARG_POINTER_REGNUM)
5202 modified_regs[i] = 1;
5205 note_stores (PATTERN (b2), mark_modified_reg);
5208 /* Check the next candidate branch insn from the label
5211 || GET_CODE (b2) != JUMP_INSN
5213 || ! condjump_p (b2)
5214 || simplejump_p (b2))
5217 /* Get the comparison codes and operands, reversing the
5218 codes if appropriate. If we don't have comparison codes,
5219 we can't do anything. */
5220 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
5221 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
5222 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
5223 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
5224 code1 = reverse_condition (code1);
5226 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
5227 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
5228 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
5229 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
5230 code2 = reverse_condition (code2);
5232 /* If they test the same things and knowing that B1 branches
5233 tells us whether or not B2 branches, check if we
5234 can thread the branch. */
5235 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
5236 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
5237 && (comparison_dominates_p (code1, code2)
5238 || (comparison_dominates_p (code1, reverse_condition (code2))
5239 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
5243 t1 = prev_nonnote_insn (b1);
5244 t2 = prev_nonnote_insn (b2);
5246 while (t1 != 0 && t2 != 0)
5250 /* We have reached the target of the first branch.
5251 If there are no pending register equivalents,
5252 we know that this branch will either always
5253 succeed (if the senses of the two branches are
5254 the same) or always fail (if not). */
5257 if (num_same_regs != 0)
5260 if (comparison_dominates_p (code1, code2))
5261 new_label = JUMP_LABEL (b2);
5263 new_label = get_label_after (b2);
5265 if (JUMP_LABEL (b1) != new_label)
5267 rtx prev = PREV_INSN (new_label);
5269 if (flag_before_loop
5270 && GET_CODE (prev) == NOTE
5271 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
5273 /* Don't thread to the loop label. If a loop
5274 label is reused, loop optimization will
5275 be disabled for that loop. */
5276 new_label = gen_label_rtx ();
5277 emit_label_after (new_label, PREV_INSN (prev));
5279 changed |= redirect_jump (b1, new_label);
5284 /* If either of these is not a normal insn (it might be
5285 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
5286 have already been skipped above.) Similarly, fail
5287 if the insns are different. */
5288 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
5289 || recog_memoized (t1) != recog_memoized (t2)
5290 || ! rtx_equal_for_thread_p (PATTERN (t1),
5294 t1 = prev_nonnote_insn (t1);
5295 t2 = prev_nonnote_insn (t2);
5302 /* This is like RTX_EQUAL_P except that it knows about our handling of
5303 possibly equivalent registers and knows to consider volatile and
5304 modified objects as not equal.
5306 YINSN is the insn containing Y. */
5309 rtx_equal_for_thread_p (x, y, yinsn)
5315 register enum rtx_code code;
5316 register const char *fmt;
5318 code = GET_CODE (x);
5319 /* Rtx's of different codes cannot be equal. */
5320 if (code != GET_CODE (y))
5323 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
5324 (REG:SI x) and (REG:HI x) are NOT equivalent. */
5326 if (GET_MODE (x) != GET_MODE (y))
5329 /* For floating-point, consider everything unequal. This is a bit
5330 pessimistic, but this pass would only rarely do anything for FP
5332 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
5333 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
5336 /* For commutative operations, the RTX match if the operand match in any
5337 order. Also handle the simple binary and unary cases without a loop. */
5338 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
5339 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
5340 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
5341 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
5342 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
5343 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
5344 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
5345 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
5346 else if (GET_RTX_CLASS (code) == '1')
5347 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
5349 /* Handle special-cases first. */
5353 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
5356 /* If neither is user variable or hard register, check for possible
5358 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
5359 || REGNO (x) < FIRST_PSEUDO_REGISTER
5360 || REGNO (y) < FIRST_PSEUDO_REGISTER)
5363 if (same_regs[REGNO (x)] == -1)
5365 same_regs[REGNO (x)] = REGNO (y);
5368 /* If this is the first time we are seeing a register on the `Y'
5369 side, see if it is the last use. If not, we can't thread the
5370 jump, so mark it as not equivalent. */
5371 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
5377 return (same_regs[REGNO (x)] == REGNO (y));
5382 /* If memory modified or either volatile, not equivalent.
5383 Else, check address. */
5384 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5387 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
5390 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
5396 /* Cancel a pending `same_regs' if setting equivalenced registers.
5397 Then process source. */
5398 if (GET_CODE (SET_DEST (x)) == REG
5399 && GET_CODE (SET_DEST (y)) == REG)
5401 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
5403 same_regs[REGNO (SET_DEST (x))] = -1;
5406 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
5410 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
5413 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
5416 return XEXP (x, 0) == XEXP (y, 0);
5419 return XSTR (x, 0) == XSTR (y, 0);
5428 fmt = GET_RTX_FORMAT (code);
5429 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5434 if (XWINT (x, i) != XWINT (y, i))
5440 if (XINT (x, i) != XINT (y, i))
5446 /* Two vectors must have the same length. */
5447 if (XVECLEN (x, i) != XVECLEN (y, i))
5450 /* And the corresponding elements must match. */
5451 for (j = 0; j < XVECLEN (x, i); j++)
5452 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
5453 XVECEXP (y, i, j), yinsn) == 0)
5458 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
5464 if (strcmp (XSTR (x, i), XSTR (y, i)))
5469 /* These are just backpointers, so they don't matter. */
5476 /* It is believed that rtx's at this level will never
5477 contain anything but integers and other rtx's,
5478 except for within LABEL_REFs and SYMBOL_REFs. */
5487 #if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
5488 /* Return the insn that NEW can be safely inserted in front of starting at
5489 the jump insn INSN. Return 0 if it is not safe to do this jump
5490 optimization. Note that NEW must contain a single set. */
5493 find_insert_position (insn, new)
5500 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
5501 if (GET_CODE (PATTERN (new)) != PARALLEL)
5504 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5505 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5506 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5513 /* There is a good chance that the previous insn PREV sets the thing
5514 being clobbered (often the CC in a hard reg). If PREV does not
5515 use what NEW sets, we can insert NEW before PREV. */
5517 prev = prev_active_insn (insn);
5518 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
5519 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
5520 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5522 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
5526 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
5528 #endif /* !HAVE_cc0 */