1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-95, 1996 Free Software Foundation, Inc.b
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. */
57 #include "hard-reg-set.h"
59 #include "insn-config.h"
60 #include "insn-flags.h"
65 /* ??? Eventually must record somehow the labels used by jumps
66 from nested functions. */
67 /* Pre-record the next or previous real insn for each label?
68 No, this pass is very fast anyway. */
69 /* Condense consecutive labels?
70 This would make life analysis faster, maybe. */
71 /* Optimize jump y; x: ... y: jumpif... x?
72 Don't know if it is worth bothering with. */
73 /* Optimize two cases of conditional jump to conditional jump?
74 This can never delete any instruction or make anything dead,
75 or even change what is live at any point.
76 So perhaps let combiner do it. */
78 /* Vector indexed by uid.
79 For each CODE_LABEL, index by its uid to get first unconditional jump
80 that jumps to the label.
81 For each JUMP_INSN, index by its uid to get the next unconditional jump
82 that jumps to the same label.
83 Element 0 is the start of a chain of all return insns.
84 (It is safe to use element 0 because insn uid 0 is not used. */
86 static rtx *jump_chain;
88 /* List of labels referred to from initializers.
89 These can never be deleted. */
92 /* Maximum index in jump_chain. */
94 static int max_jump_chain;
96 /* Set nonzero by jump_optimize if control can fall through
97 to the end of the function. */
100 /* Indicates whether death notes are significant in cross jump analysis.
101 Normally they are not significant, because of A and B jump to C,
102 and R dies in A, it must die in B. But this might not be true after
103 stack register conversion, and we must compare death notes in that
106 static int cross_jump_death_matters = 0;
108 static int duplicate_loop_exit_test PROTO((rtx));
109 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
110 static void do_cross_jump PROTO((rtx, rtx, rtx));
111 static int jump_back_p PROTO((rtx, rtx));
112 static int tension_vector_labels PROTO((rtx, int));
113 static void mark_jump_label PROTO((rtx, rtx, int));
114 static void delete_computation PROTO((rtx));
115 static void delete_from_jump_chain PROTO((rtx));
116 static int delete_labelref_insn PROTO((rtx, rtx, int));
117 static void redirect_tablejump PROTO((rtx, rtx));
119 /* Delete no-op jumps and optimize jumps to jumps
120 and jumps around jumps.
121 Delete unused labels and unreachable code.
123 If CROSS_JUMP is 1, detect matching code
124 before a jump and its destination and unify them.
125 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
127 If NOOP_MOVES is nonzero, delete no-op move insns.
129 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
130 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
132 If `optimize' is zero, don't change any code,
133 just determine whether control drops off the end of the function.
134 This case occurs when we have -W and not -O.
135 It works because `delete_insn' checks the value of `optimize'
136 and refrains from actually deleting when that is 0. */
139 jump_optimize (f, cross_jump, noop_moves, after_regscan)
145 register rtx insn, next, note;
151 cross_jump_death_matters = (cross_jump == 2);
153 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
154 notes whose labels don't occur in the insn any more. */
156 for (insn = f; insn; insn = NEXT_INSN (insn))
158 if (GET_CODE (insn) == CODE_LABEL)
159 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
160 else if (GET_CODE (insn) == JUMP_INSN)
161 JUMP_LABEL (insn) = 0;
162 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
163 for (note = REG_NOTES (insn); note; note = next)
165 next = XEXP (note, 1);
166 if (REG_NOTE_KIND (note) == REG_LABEL
167 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
168 remove_note (insn, note);
171 if (INSN_UID (insn) > max_uid)
172 max_uid = INSN_UID (insn);
177 /* Delete insns following barriers, up to next label. */
179 for (insn = f; insn;)
181 if (GET_CODE (insn) == BARRIER)
183 insn = NEXT_INSN (insn);
184 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
186 if (GET_CODE (insn) == NOTE
187 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
188 insn = NEXT_INSN (insn);
190 insn = delete_insn (insn);
192 /* INSN is now the code_label. */
195 insn = NEXT_INSN (insn);
198 /* Leave some extra room for labels and duplicate exit test insns
200 max_jump_chain = max_uid * 14 / 10;
201 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
202 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
204 /* Mark the label each jump jumps to.
205 Combine consecutive labels, and count uses of labels.
207 For each label, make a chain (using `jump_chain')
208 of all the *unconditional* jumps that jump to it;
209 also make a chain of all returns. */
211 for (insn = f; insn; insn = NEXT_INSN (insn))
212 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
213 && ! INSN_DELETED_P (insn))
215 mark_jump_label (PATTERN (insn), insn, cross_jump);
216 if (GET_CODE (insn) == JUMP_INSN)
218 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
220 jump_chain[INSN_UID (insn)]
221 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
222 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
224 if (GET_CODE (PATTERN (insn)) == RETURN)
226 jump_chain[INSN_UID (insn)] = jump_chain[0];
227 jump_chain[0] = insn;
232 /* Keep track of labels used from static data;
233 they cannot ever be deleted. */
235 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
236 LABEL_NUSES (XEXP (insn, 0))++;
238 check_exception_handler_labels ();
240 /* Keep track of labels used for marking handlers for exception
241 regions; they cannot usually be deleted. */
243 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
244 LABEL_NUSES (XEXP (insn, 0))++;
246 exception_optimize ();
248 /* Delete all labels already not referenced.
249 Also find the last insn. */
252 for (insn = f; insn; )
254 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
255 insn = delete_insn (insn);
259 insn = NEXT_INSN (insn);
265 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
266 If so record that this function can drop off the end. */
272 /* One label can follow the end-note: the return label. */
273 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
274 /* Ordinary insns can follow it if returning a structure. */
275 || GET_CODE (insn) == INSN
276 /* If machine uses explicit RETURN insns, no epilogue,
277 then one of them follows the note. */
278 || (GET_CODE (insn) == JUMP_INSN
279 && GET_CODE (PATTERN (insn)) == RETURN)
280 /* A barrier can follow the return insn. */
281 || GET_CODE (insn) == BARRIER
282 /* Other kinds of notes can follow also. */
283 || (GET_CODE (insn) == NOTE
284 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
285 insn = PREV_INSN (insn);
288 /* Report if control can fall through at the end of the function. */
289 if (insn && GET_CODE (insn) == NOTE
290 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
291 && ! INSN_DELETED_P (insn))
294 /* Zero the "deleted" flag of all the "deleted" insns. */
295 for (insn = f; insn; insn = NEXT_INSN (insn))
296 INSN_DELETED_P (insn) = 0;
303 /* If we fall through to the epilogue, see if we can insert a RETURN insn
304 in front of it. If the machine allows it at this point (we might be
305 after reload for a leaf routine), it will improve optimization for it
307 insn = get_last_insn ();
308 while (insn && GET_CODE (insn) == NOTE)
309 insn = PREV_INSN (insn);
311 if (insn && GET_CODE (insn) != BARRIER)
313 emit_jump_insn (gen_return ());
320 for (insn = f; insn; )
322 next = NEXT_INSN (insn);
324 if (GET_CODE (insn) == INSN)
326 register rtx body = PATTERN (insn);
328 /* Combine stack_adjusts with following push_insns. */
330 if (GET_CODE (body) == SET
331 && SET_DEST (body) == stack_pointer_rtx
332 && GET_CODE (SET_SRC (body)) == PLUS
333 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
334 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
335 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
338 rtx stack_adjust_insn = insn;
339 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
340 int total_pushed = 0;
343 /* Find all successive push insns. */
345 /* Don't convert more than three pushes;
346 that starts adding too many displaced addresses
347 and the whole thing starts becoming a losing
352 p = next_nonnote_insn (p);
353 if (p == 0 || GET_CODE (p) != INSN)
356 if (GET_CODE (pbody) != SET)
358 dest = SET_DEST (pbody);
359 /* Allow a no-op move between the adjust and the push. */
360 if (GET_CODE (dest) == REG
361 && GET_CODE (SET_SRC (pbody)) == REG
362 && REGNO (dest) == REGNO (SET_SRC (pbody)))
364 if (! (GET_CODE (dest) == MEM
365 && GET_CODE (XEXP (dest, 0)) == POST_INC
366 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
369 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
370 > stack_adjust_amount)
372 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
375 /* Discard the amount pushed from the stack adjust;
376 maybe eliminate it entirely. */
377 if (total_pushed >= stack_adjust_amount)
379 delete_computation (stack_adjust_insn);
380 total_pushed = stack_adjust_amount;
383 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
384 = GEN_INT (stack_adjust_amount - total_pushed);
386 /* Change the appropriate push insns to ordinary stores. */
388 while (total_pushed > 0)
391 p = next_nonnote_insn (p);
392 if (GET_CODE (p) != INSN)
395 if (GET_CODE (pbody) == SET)
397 dest = SET_DEST (pbody);
398 if (! (GET_CODE (dest) == MEM
399 && GET_CODE (XEXP (dest, 0)) == POST_INC
400 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
402 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
403 /* If this push doesn't fully fit in the space
404 of the stack adjust that we deleted,
405 make another stack adjust here for what we
406 didn't use up. There should be peepholes
407 to recognize the resulting sequence of insns. */
408 if (total_pushed < 0)
410 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
411 GEN_INT (- total_pushed)),
416 = plus_constant (stack_pointer_rtx, total_pushed);
421 /* Detect and delete no-op move instructions
422 resulting from not allocating a parameter in a register. */
424 if (GET_CODE (body) == SET
425 && (SET_DEST (body) == SET_SRC (body)
426 || (GET_CODE (SET_DEST (body)) == MEM
427 && GET_CODE (SET_SRC (body)) == MEM
428 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
429 && ! (GET_CODE (SET_DEST (body)) == MEM
430 && MEM_VOLATILE_P (SET_DEST (body)))
431 && ! (GET_CODE (SET_SRC (body)) == MEM
432 && MEM_VOLATILE_P (SET_SRC (body))))
433 delete_computation (insn);
435 /* Detect and ignore no-op move instructions
436 resulting from smart or fortuitous register allocation. */
438 else if (GET_CODE (body) == SET)
440 int sreg = true_regnum (SET_SRC (body));
441 int dreg = true_regnum (SET_DEST (body));
443 if (sreg == dreg && sreg >= 0)
445 else if (sreg >= 0 && dreg >= 0)
448 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
449 sreg, NULL_PTR, dreg,
450 GET_MODE (SET_SRC (body)));
453 GET_MODE (tem) == GET_MODE (SET_DEST (body)))
455 /* DREG may have been the target of a REG_DEAD note in
456 the insn which makes INSN redundant. If so, reorg
457 would still think it is dead. So search for such a
458 note and delete it if we find it. */
459 if (! find_regno_note (insn, REG_UNUSED, dreg))
460 for (trial = prev_nonnote_insn (insn);
461 trial && GET_CODE (trial) != CODE_LABEL;
462 trial = prev_nonnote_insn (trial))
463 if (find_regno_note (trial, REG_DEAD, dreg))
465 remove_death (dreg, trial);
468 #ifdef PRESERVE_DEATH_INFO_REGNO_P
469 /* Deleting insn could lose a death-note for SREG
470 so don't do it if final needs accurate
472 if (PRESERVE_DEATH_INFO_REGNO_P (sreg)
473 && (trial = find_regno_note (insn, REG_DEAD, sreg)))
475 /* Change this into a USE so that we won't emit
476 code for it, but still can keep the note. */
478 = gen_rtx (USE, VOIDmode, XEXP (trial, 0));
479 /* Remove all reg notes but the REG_DEAD one. */
480 REG_NOTES (insn) = trial;
481 XEXP (trial, 1) = NULL_RTX;
488 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
489 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
491 GET_MODE (SET_DEST (body))))
493 /* This handles the case where we have two consecutive
494 assignments of the same constant to pseudos that didn't
495 get a hard reg. Each SET from the constant will be
496 converted into a SET of the spill register and an
497 output reload will be made following it. This produces
498 two loads of the same constant into the same spill
503 /* Look back for a death note for the first reg.
504 If there is one, it is no longer accurate. */
505 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
507 if ((GET_CODE (in_insn) == INSN
508 || GET_CODE (in_insn) == JUMP_INSN)
509 && find_regno_note (in_insn, REG_DEAD, dreg))
511 remove_death (dreg, in_insn);
514 in_insn = PREV_INSN (in_insn);
517 /* Delete the second load of the value. */
521 else if (GET_CODE (body) == PARALLEL)
523 /* If each part is a set between two identical registers or
524 a USE or CLOBBER, delete the insn. */
528 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
530 tem = XVECEXP (body, 0, i);
531 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
534 if (GET_CODE (tem) != SET
535 || (sreg = true_regnum (SET_SRC (tem))) < 0
536 || (dreg = true_regnum (SET_DEST (tem))) < 0
544 /* Also delete insns to store bit fields if they are no-ops. */
545 /* Not worth the hair to detect this in the big-endian case. */
546 else if (! BYTES_BIG_ENDIAN
547 && GET_CODE (body) == SET
548 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
549 && XEXP (SET_DEST (body), 2) == const0_rtx
550 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
551 && ! (GET_CODE (SET_SRC (body)) == MEM
552 && MEM_VOLATILE_P (SET_SRC (body))))
558 /* If we haven't yet gotten to reload and we have just run regscan,
559 delete any insn that sets a register that isn't used elsewhere.
560 This helps some of the optimizations below by having less insns
561 being jumped around. */
563 if (! reload_completed && after_regscan)
564 for (insn = f; insn; insn = next)
566 rtx set = single_set (insn);
568 next = NEXT_INSN (insn);
570 if (set && GET_CODE (SET_DEST (set)) == REG
571 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
572 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
573 /* We use regno_last_note_uid so as not to delete the setting
574 of a reg that's used in notes. A subsequent optimization
575 might arrange to use that reg for real. */
576 && regno_last_note_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
577 && ! side_effects_p (SET_SRC (set))
578 && ! find_reg_note (insn, REG_RETVAL, 0))
582 /* Now iterate optimizing jumps until nothing changes over one pass. */
588 for (insn = f; insn; insn = next)
591 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
593 int this_is_simplejump, this_is_condjump, reversep;
594 int this_is_condjump_in_parallel;
596 /* If NOT the first iteration, if this is the last jump pass
597 (just before final), do the special peephole optimizations.
598 Avoiding the first iteration gives ordinary jump opts
599 a chance to work before peephole opts. */
601 if (reload_completed && !first && !flag_no_peephole)
602 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
606 /* That could have deleted some insns after INSN, so check now
607 what the following insn is. */
609 next = NEXT_INSN (insn);
611 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
612 jump. Try to optimize by duplicating the loop exit test if so.
613 This is only safe immediately after regscan, because it uses
614 the values of regno_first_uid and regno_last_uid. */
615 if (after_regscan && GET_CODE (insn) == NOTE
616 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
617 && (temp1 = next_nonnote_insn (insn)) != 0
618 && simplejump_p (temp1))
620 temp = PREV_INSN (insn);
621 if (duplicate_loop_exit_test (insn))
624 next = NEXT_INSN (temp);
629 if (GET_CODE (insn) != JUMP_INSN)
632 this_is_simplejump = simplejump_p (insn);
633 this_is_condjump = condjump_p (insn);
634 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
636 /* Tension the labels in dispatch tables. */
638 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
639 changed |= tension_vector_labels (PATTERN (insn), 0);
640 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
641 changed |= tension_vector_labels (PATTERN (insn), 1);
643 /* If a dispatch table always goes to the same place,
644 get rid of it and replace the insn that uses it. */
646 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
647 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
650 rtx pat = PATTERN (insn);
651 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
652 int len = XVECLEN (pat, diff_vec_p);
653 rtx dispatch = prev_real_insn (insn);
655 for (i = 0; i < len; i++)
656 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
657 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
661 && GET_CODE (dispatch) == JUMP_INSN
662 && JUMP_LABEL (dispatch) != 0
663 /* Don't mess with a casesi insn. */
664 && !(GET_CODE (PATTERN (dispatch)) == SET
665 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
667 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
669 redirect_tablejump (dispatch,
670 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
675 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
677 /* If a jump references the end of the function, try to turn
678 it into a RETURN insn, possibly a conditional one. */
679 if (JUMP_LABEL (insn)
680 && (next_active_insn (JUMP_LABEL (insn)) == 0
681 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
683 changed |= redirect_jump (insn, NULL_RTX);
685 /* Detect jump to following insn. */
686 if (reallabelprev == insn && condjump_p (insn))
688 next = next_real_insn (JUMP_LABEL (insn));
694 /* If we have an unconditional jump preceded by a USE, try to put
695 the USE before the target and jump there. This simplifies many
696 of the optimizations below since we don't have to worry about
697 dealing with these USE insns. We only do this if the label
698 being branch to already has the identical USE or if code
699 never falls through to that label. */
701 if (this_is_simplejump
702 && (temp = prev_nonnote_insn (insn)) != 0
703 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
704 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
705 && (GET_CODE (temp1) == BARRIER
706 || (GET_CODE (temp1) == INSN
707 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
708 /* Don't do this optimization if we have a loop containing only
709 the USE instruction, and the loop start label has a usage
710 count of 1. This is because we will redo this optimization
711 everytime through the outer loop, and jump opt will never
713 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
714 && temp2 == JUMP_LABEL (insn)
715 && LABEL_NUSES (temp2) == 1))
717 if (GET_CODE (temp1) == BARRIER)
719 emit_insn_after (PATTERN (temp), temp1);
720 temp1 = NEXT_INSN (temp1);
724 redirect_jump (insn, get_label_before (temp1));
725 reallabelprev = prev_real_insn (temp1);
729 /* Simplify if (...) x = a; else x = b; by converting it
730 to x = b; if (...) x = a;
731 if B is sufficiently simple, the test doesn't involve X,
732 and nothing in the test modifies B or X.
734 If we have small register classes, we also can't do this if X
737 If the "x = b;" insn has any REG_NOTES, we don't do this because
738 of the possibility that we are running after CSE and there is a
739 REG_EQUAL note that is only valid if the branch has already been
740 taken. If we move the insn with the REG_EQUAL note, we may
741 fold the comparison to always be false in a later CSE pass.
742 (We could also delete the REG_NOTES when moving the insn, but it
743 seems simpler to not move it.) An exception is that we can move
744 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
745 value is the same as "b".
747 INSN is the branch over the `else' part.
751 TEMP to the jump insn preceding "x = a;"
753 TEMP2 to the insn that sets "x = b;"
754 TEMP3 to the insn that sets "x = a;"
755 TEMP4 to the set of "x = b"; */
757 if (this_is_simplejump
758 && (temp3 = prev_active_insn (insn)) != 0
759 && GET_CODE (temp3) == INSN
760 && (temp4 = single_set (temp3)) != 0
761 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
762 #ifdef SMALL_REGISTER_CLASSES
763 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
765 && (temp2 = next_active_insn (insn)) != 0
766 && GET_CODE (temp2) == INSN
767 && (temp4 = single_set (temp2)) != 0
768 && rtx_equal_p (SET_DEST (temp4), temp1)
769 && (GET_CODE (SET_SRC (temp4)) == REG
770 || GET_CODE (SET_SRC (temp4)) == SUBREG
771 || CONSTANT_P (SET_SRC (temp4)))
772 && (REG_NOTES (temp2) == 0
773 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
774 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
775 && XEXP (REG_NOTES (temp2), 1) == 0
776 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
778 && (temp = prev_active_insn (temp3)) != 0
779 && condjump_p (temp) && ! simplejump_p (temp)
780 /* TEMP must skip over the "x = a;" insn */
781 && prev_real_insn (JUMP_LABEL (temp)) == insn
782 && no_labels_between_p (insn, JUMP_LABEL (temp))
783 /* There must be no other entries to the "x = b;" insn. */
784 && no_labels_between_p (JUMP_LABEL (temp), temp2)
785 /* INSN must either branch to the insn after TEMP2 or the insn
786 after TEMP2 must branch to the same place as INSN. */
787 && (reallabelprev == temp2
788 || ((temp5 = next_active_insn (temp2)) != 0
789 && simplejump_p (temp5)
790 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
792 /* The test expression, X, may be a complicated test with
793 multiple branches. See if we can find all the uses of
794 the label that TEMP branches to without hitting a CALL_INSN
795 or a jump to somewhere else. */
796 rtx target = JUMP_LABEL (temp);
797 int nuses = LABEL_NUSES (target);
800 /* Set P to the first jump insn that goes around "x = a;". */
801 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
803 if (GET_CODE (p) == JUMP_INSN)
805 if (condjump_p (p) && ! simplejump_p (p)
806 && JUMP_LABEL (p) == target)
815 else if (GET_CODE (p) == CALL_INSN)
820 /* We cannot insert anything between a set of cc and its use
821 so if P uses cc0, we must back up to the previous insn. */
822 q = prev_nonnote_insn (p);
823 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
824 && sets_cc0_p (PATTERN (q)))
831 /* If we found all the uses and there was no data conflict, we
832 can move the assignment unless we can branch into the middle
835 && no_labels_between_p (p, insn)
836 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
837 && ! reg_set_between_p (temp1, p, temp3)
838 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
839 || ! reg_set_between_p (SET_SRC (temp4), p, temp2)))
841 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
844 /* Set NEXT to an insn that we know won't go away. */
845 next = next_active_insn (insn);
847 /* Delete the jump around the set. Note that we must do
848 this before we redirect the test jumps so that it won't
849 delete the code immediately following the assignment
850 we moved (which might be a jump). */
854 /* We either have two consecutive labels or a jump to
855 a jump, so adjust all the JUMP_INSNs to branch to where
857 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
858 if (GET_CODE (p) == JUMP_INSN)
859 redirect_jump (p, target);
867 /* If we have if (...) x = exp; and branches are expensive,
868 EXP is a single insn, does not have any side effects, cannot
869 trap, and is not too costly, convert this to
870 t = exp; if (...) x = t;
872 Don't do this when we have CC0 because it is unlikely to help
873 and we'd need to worry about where to place the new insn and
874 the potential for conflicts. We also can't do this when we have
875 notes on the insn for the same reason as above.
879 TEMP to the "x = exp;" insn.
880 TEMP1 to the single set in the "x = exp; insn.
883 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 && (reallabelprev == temp
890 || ((temp2 = next_active_insn (temp)) != 0
891 && simplejump_p (temp2)
892 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
893 && (temp1 = single_set (temp)) != 0
894 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
895 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
896 #ifdef SMALL_REGISTER_CLASSES
897 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
899 && GET_CODE (SET_SRC (temp1)) != REG
900 && GET_CODE (SET_SRC (temp1)) != SUBREG
901 && GET_CODE (SET_SRC (temp1)) != CONST_INT
902 && ! side_effects_p (SET_SRC (temp1))
903 && ! may_trap_p (SET_SRC (temp1))
904 && rtx_cost (SET_SRC (temp1), SET) < 10)
906 rtx new = gen_reg_rtx (GET_MODE (temp2));
908 if (validate_change (temp, &SET_DEST (temp1), new, 0))
910 next = emit_insn_after (gen_move_insn (temp2, new), insn);
911 emit_insn_after_with_line_notes (PATTERN (temp),
912 PREV_INSN (insn), temp);
914 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
918 /* Similarly, if it takes two insns to compute EXP but they
919 have the same destination. Here TEMP3 will be the second
920 insn and TEMP4 the SET from that insn. */
922 if (! reload_completed
923 && this_is_condjump && ! this_is_simplejump
925 && (temp = next_nonnote_insn (insn)) != 0
926 && GET_CODE (temp) == INSN
927 && REG_NOTES (temp) == 0
928 && (temp3 = next_nonnote_insn (temp)) != 0
929 && GET_CODE (temp3) == INSN
930 && REG_NOTES (temp3) == 0
931 && (reallabelprev == temp3
932 || ((temp2 = next_active_insn (temp3)) != 0
933 && simplejump_p (temp2)
934 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
935 && (temp1 = single_set (temp)) != 0
936 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
937 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
938 #ifdef SMALL_REGISTER_CLASSES
939 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
941 && ! side_effects_p (SET_SRC (temp1))
942 && ! may_trap_p (SET_SRC (temp1))
943 && rtx_cost (SET_SRC (temp1), SET) < 10
944 && (temp4 = single_set (temp3)) != 0
945 && rtx_equal_p (SET_DEST (temp4), temp2)
946 && ! side_effects_p (SET_SRC (temp4))
947 && ! may_trap_p (SET_SRC (temp4))
948 && rtx_cost (SET_SRC (temp4), SET) < 10)
950 rtx new = gen_reg_rtx (GET_MODE (temp2));
952 if (validate_change (temp, &SET_DEST (temp1), new, 0))
954 next = emit_insn_after (gen_move_insn (temp2, new), insn);
955 emit_insn_after_with_line_notes (PATTERN (temp),
956 PREV_INSN (insn), temp);
957 emit_insn_after_with_line_notes
958 (replace_rtx (PATTERN (temp3), temp2, new),
959 PREV_INSN (insn), temp3);
962 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
966 /* Finally, handle the case where two insns are used to
967 compute EXP but a temporary register is used. Here we must
968 ensure that the temporary register is not used anywhere else. */
970 if (! reload_completed
972 && this_is_condjump && ! this_is_simplejump
974 && (temp = next_nonnote_insn (insn)) != 0
975 && GET_CODE (temp) == INSN
976 && REG_NOTES (temp) == 0
977 && (temp3 = next_nonnote_insn (temp)) != 0
978 && GET_CODE (temp3) == INSN
979 && REG_NOTES (temp3) == 0
980 && (reallabelprev == temp3
981 || ((temp2 = next_active_insn (temp3)) != 0
982 && simplejump_p (temp2)
983 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
984 && (temp1 = single_set (temp)) != 0
985 && (temp5 = SET_DEST (temp1),
986 (GET_CODE (temp5) == REG
987 || (GET_CODE (temp5) == SUBREG
988 && (temp5 = SUBREG_REG (temp5),
989 GET_CODE (temp5) == REG))))
990 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
991 && regno_first_uid[REGNO (temp5)] == INSN_UID (temp)
992 && regno_last_uid[REGNO (temp5)] == INSN_UID (temp3)
993 && ! side_effects_p (SET_SRC (temp1))
994 && ! may_trap_p (SET_SRC (temp1))
995 && rtx_cost (SET_SRC (temp1), SET) < 10
996 && (temp4 = single_set (temp3)) != 0
997 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
998 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
999 #ifdef SMALL_REGISTER_CLASSES
1000 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
1002 && rtx_equal_p (SET_DEST (temp4), temp2)
1003 && ! side_effects_p (SET_SRC (temp4))
1004 && ! may_trap_p (SET_SRC (temp4))
1005 && rtx_cost (SET_SRC (temp4), SET) < 10)
1007 rtx new = gen_reg_rtx (GET_MODE (temp2));
1009 if (validate_change (temp3, &SET_DEST (temp4), new, 0))
1011 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1012 emit_insn_after_with_line_notes (PATTERN (temp),
1013 PREV_INSN (insn), temp);
1014 emit_insn_after_with_line_notes (PATTERN (temp3),
1015 PREV_INSN (insn), temp3);
1017 delete_insn (temp3);
1018 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1021 #endif /* HAVE_cc0 */
1023 /* Try to use a conditional move (if the target has them), or a
1024 store-flag insn. The general case is:
1026 1) x = a; if (...) x = b; and
1029 If the jump would be faster, the machine should not have defined
1030 the movcc or scc insns!. These cases are often made by the
1031 previous optimization.
1033 The second case is treated as x = x; if (...) x = b;.
1035 INSN here is the jump around the store. We set:
1037 TEMP to the "x = b;" insn.
1040 TEMP3 to A (X in the second case).
1041 TEMP4 to the condition being tested.
1042 TEMP5 to the earliest insn used to find the condition. */
1044 if (/* We can't do this after reload has completed. */
1046 && this_is_condjump && ! this_is_simplejump
1047 /* Set TEMP to the "x = b;" insn. */
1048 && (temp = next_nonnote_insn (insn)) != 0
1049 && GET_CODE (temp) == INSN
1050 && GET_CODE (PATTERN (temp)) == SET
1051 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1052 #ifdef SMALL_REGISTER_CLASSES
1053 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
1055 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1056 || GET_CODE (temp2) == SUBREG
1057 /* ??? How about floating point constants? */
1058 || GET_CODE (temp2) == CONST_INT)
1059 /* Allow either form, but prefer the former if both apply.
1060 There is no point in using the old value of TEMP1 if
1061 it is a register, since cse will alias them. It can
1062 lose if the old value were a hard register since CSE
1063 won't replace hard registers. */
1064 && (((temp3 = reg_set_last (temp1, insn)) != 0)
1065 /* Make the latter case look like x = x; if (...) x = b; */
1066 || (temp3 = temp1, 1))
1067 /* INSN must either branch to the insn after TEMP or the insn
1068 after TEMP must branch to the same place as INSN. */
1069 && (reallabelprev == temp
1070 || ((temp4 = next_active_insn (temp)) != 0
1071 && simplejump_p (temp4)
1072 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1073 && (temp4 = get_condition (insn, &temp5)) != 0
1074 /* We must be comparing objects whose modes imply the size.
1075 We could handle BLKmode if (1) emit_store_flag could
1076 and (2) we could find the size reliably. */
1077 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1078 /* No point in doing any of this if branches are cheap or we
1079 don't have conditional moves. */
1080 && (BRANCH_COST >= 2
1081 #ifdef HAVE_conditional_move
1086 /* If the previous insn sets CC0 and something else, we can't
1087 do this since we are going to delete that insn. */
1089 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1090 && GET_CODE (temp6) == INSN
1091 && (sets_cc0_p (PATTERN (temp6)) == -1
1092 || (sets_cc0_p (PATTERN (temp6)) == 1
1093 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1097 #ifdef HAVE_conditional_move
1098 /* First try a conditional move. */
1100 enum rtx_code code = GET_CODE (temp4);
1102 rtx cond0, cond1, aval, bval;
1105 /* Copy the compared variables into cond0 and cond1, so that
1106 any side effects performed in or after the old comparison,
1107 will not affect our compare which will come later. */
1108 /* ??? Is it possible to just use the comparison in the jump
1109 insn? After all, we're going to delete it. We'd have
1110 to modify emit_conditional_move to take a comparison rtx
1111 instead or write a new function. */
1112 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1113 /* We want the target to be able to simplify comparisons with
1114 zero (and maybe other constants as well), so don't create
1115 pseudos for them. There's no need to either. */
1116 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1117 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1118 cond1 = XEXP (temp4, 1);
1120 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1126 target = emit_conditional_move (var, code,
1127 cond0, cond1, VOIDmode,
1128 aval, bval, GET_MODE (var),
1129 (code == LTU || code == GEU
1130 || code == LEU || code == GTU));
1136 /* Save the conditional move sequence but don't emit it
1137 yet. On some machines, like the alpha, it is possible
1138 that temp5 == insn, so next generate the sequence that
1139 saves the compared values and then emit both
1140 sequences ensuring seq1 occurs before seq2. */
1141 seq2 = get_insns ();
1144 /* Now that we can't fail, generate the copy insns that
1145 preserve the compared values. */
1147 emit_move_insn (cond0, XEXP (temp4, 0));
1148 if (cond1 != XEXP (temp4, 1))
1149 emit_move_insn (cond1, XEXP (temp4, 1));
1150 seq1 = get_insns ();
1153 emit_insns_before (seq1, temp5);
1154 /* Insert conditional move after insn, to be sure that
1155 the jump and a possible compare won't be separated */
1156 emit_insns_after (seq2, insn);
1158 /* ??? We can also delete the insn that sets X to A.
1159 Flow will do it too though. */
1161 next = NEXT_INSN (insn);
1171 /* That didn't work, try a store-flag insn.
1173 We further divide the cases into:
1175 1) x = a; if (...) x = b; and either A or B is zero,
1176 2) if (...) x = 0; and jumps are expensive,
1177 3) x = a; if (...) x = b; and A and B are constants where all
1178 the set bits in A are also set in B and jumps are expensive,
1179 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1181 5) if (...) x = b; if jumps are even more expensive. */
1183 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1184 && ((GET_CODE (temp3) == CONST_INT)
1185 /* Make the latter case look like
1186 x = x; if (...) x = 0; */
1189 && temp2 == const0_rtx)
1190 || BRANCH_COST >= 3)))
1191 /* If B is zero, OK; if A is zero, can only do (1) if we
1192 can reverse the condition. See if (3) applies possibly
1193 by reversing the condition. Prefer reversing to (4) when
1194 branches are very expensive. */
1195 && ((reversep = 0, temp2 == const0_rtx)
1196 || (temp3 == const0_rtx
1197 && (reversep = can_reverse_comparison_p (temp4, insn)))
1198 || (BRANCH_COST >= 2
1199 && GET_CODE (temp2) == CONST_INT
1200 && GET_CODE (temp3) == CONST_INT
1201 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1202 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1203 && (reversep = can_reverse_comparison_p (temp4,
1205 || BRANCH_COST >= 3)
1208 enum rtx_code code = GET_CODE (temp4);
1209 rtx uval, cval, var = temp1;
1213 /* If necessary, reverse the condition. */
1215 code = reverse_condition (code), uval = temp2, cval = temp3;
1217 uval = temp3, cval = temp2;
1219 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1220 is the constant 1, it is best to just compute the result
1221 directly. If UVAL is constant and STORE_FLAG_VALUE
1222 includes all of its bits, it is best to compute the flag
1223 value unnormalized and `and' it with UVAL. Otherwise,
1224 normalize to -1 and `and' with UVAL. */
1225 normalizep = (cval != const0_rtx ? -1
1226 : (uval == const1_rtx ? 1
1227 : (GET_CODE (uval) == CONST_INT
1228 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1231 /* We will be putting the store-flag insn immediately in
1232 front of the comparison that was originally being done,
1233 so we know all the variables in TEMP4 will be valid.
1234 However, this might be in front of the assignment of
1235 A to VAR. If it is, it would clobber the store-flag
1236 we will be emitting.
1238 Therefore, emit into a temporary which will be copied to
1239 VAR immediately after TEMP. */
1242 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1243 XEXP (temp4, 0), XEXP (temp4, 1),
1245 (code == LTU || code == LEU
1246 || code == GEU || code == GTU),
1256 /* Put the store-flag insns in front of the first insn
1257 used to compute the condition to ensure that we
1258 use the same values of them as the current
1259 comparison. However, the remainder of the insns we
1260 generate will be placed directly in front of the
1261 jump insn, in case any of the pseudos we use
1262 are modified earlier. */
1264 emit_insns_before (seq, temp5);
1268 /* Both CVAL and UVAL are non-zero. */
1269 if (cval != const0_rtx && uval != const0_rtx)
1273 tem1 = expand_and (uval, target, NULL_RTX);
1274 if (GET_CODE (cval) == CONST_INT
1275 && GET_CODE (uval) == CONST_INT
1276 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1280 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1281 target, NULL_RTX, 0);
1282 tem2 = expand_and (cval, tem2,
1283 (GET_CODE (tem2) == REG
1287 /* If we usually make new pseudos, do so here. This
1288 turns out to help machines that have conditional
1290 /* ??? Conditional moves have already been handled.
1291 This may be obsolete. */
1293 if (flag_expensive_optimizations)
1296 target = expand_binop (GET_MODE (var), ior_optab,
1300 else if (normalizep != 1)
1302 /* We know that either CVAL or UVAL is zero. If
1303 UVAL is zero, negate TARGET and `and' with CVAL.
1304 Otherwise, `and' with UVAL. */
1305 if (uval == const0_rtx)
1307 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1308 target, NULL_RTX, 0);
1312 target = expand_and (uval, target,
1313 (GET_CODE (target) == REG
1314 && ! preserve_subexpressions_p ()
1315 ? target : NULL_RTX));
1318 emit_move_insn (var, target);
1322 /* If INSN uses CC0, we must not separate it from the
1323 insn that sets cc0. */
1324 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1325 before = prev_nonnote_insn (before);
1327 emit_insns_before (seq, before);
1330 next = NEXT_INSN (insn);
1340 /* If branches are expensive, convert
1341 if (foo) bar++; to bar += (foo != 0);
1342 and similarly for "bar--;"
1344 INSN is the conditional branch around the arithmetic. We set:
1346 TEMP is the arithmetic insn.
1347 TEMP1 is the SET doing the arithmetic.
1348 TEMP2 is the operand being incremented or decremented.
1349 TEMP3 to the condition being tested.
1350 TEMP4 to the earliest insn used to find the condition. */
1352 if ((BRANCH_COST >= 2
1360 && ! reload_completed
1361 && this_is_condjump && ! this_is_simplejump
1362 && (temp = next_nonnote_insn (insn)) != 0
1363 && (temp1 = single_set (temp)) != 0
1364 && (temp2 = SET_DEST (temp1),
1365 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1366 && GET_CODE (SET_SRC (temp1)) == PLUS
1367 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1368 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1369 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1370 && ! side_effects_p (temp2)
1371 && ! may_trap_p (temp2)
1372 /* INSN must either branch to the insn after TEMP or the insn
1373 after TEMP must branch to the same place as INSN. */
1374 && (reallabelprev == temp
1375 || ((temp3 = next_active_insn (temp)) != 0
1376 && simplejump_p (temp3)
1377 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1378 && (temp3 = get_condition (insn, &temp4)) != 0
1379 /* We must be comparing objects whose modes imply the size.
1380 We could handle BLKmode if (1) emit_store_flag could
1381 and (2) we could find the size reliably. */
1382 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1383 && can_reverse_comparison_p (temp3, insn))
1385 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1386 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1390 /* It must be the case that TEMP2 is not modified in the range
1391 [TEMP4, INSN). The one exception we make is if the insn
1392 before INSN sets TEMP2 to something which is also unchanged
1393 in that range. In that case, we can move the initialization
1394 into our sequence. */
1396 if ((temp5 = prev_active_insn (insn)) != 0
1397 && GET_CODE (temp5) == INSN
1398 && (temp6 = single_set (temp5)) != 0
1399 && rtx_equal_p (temp2, SET_DEST (temp6))
1400 && (CONSTANT_P (SET_SRC (temp6))
1401 || GET_CODE (SET_SRC (temp6)) == REG
1402 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1404 emit_insn (PATTERN (temp5));
1406 init = SET_SRC (temp6);
1409 if (CONSTANT_P (init)
1410 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1411 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1412 XEXP (temp3, 0), XEXP (temp3, 1),
1414 (code == LTU || code == LEU
1415 || code == GTU || code == GEU), 1);
1417 /* If we can do the store-flag, do the addition or
1421 target = expand_binop (GET_MODE (temp2),
1422 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1423 ? add_optab : sub_optab),
1424 temp2, target, temp2, 0, OPTAB_WIDEN);
1428 /* Put the result back in temp2 in case it isn't already.
1429 Then replace the jump, possible a CC0-setting insn in
1430 front of the jump, and TEMP, with the sequence we have
1433 if (target != temp2)
1434 emit_move_insn (temp2, target);
1439 emit_insns_before (seq, temp4);
1443 delete_insn (init_insn);
1445 next = NEXT_INSN (insn);
1447 delete_insn (prev_nonnote_insn (insn));
1457 /* Simplify if (...) x = 1; else {...} if (x) ...
1458 We recognize this case scanning backwards as well.
1460 TEMP is the assignment to x;
1461 TEMP1 is the label at the head of the second if. */
1462 /* ?? This should call get_condition to find the values being
1463 compared, instead of looking for a COMPARE insn when HAVE_cc0
1464 is not defined. This would allow it to work on the m88k. */
1465 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1466 is not defined and the condition is tested by a separate compare
1467 insn. This is because the code below assumes that the result
1468 of the compare dies in the following branch.
1470 Not only that, but there might be other insns between the
1471 compare and branch whose results are live. Those insns need
1474 A way to fix this is to move the insns at JUMP_LABEL (insn)
1475 to before INSN. If we are running before flow, they will
1476 be deleted if they aren't needed. But this doesn't work
1479 This is really a special-case of jump threading, anyway. The
1480 right thing to do is to replace this and jump threading with
1481 much simpler code in cse.
1483 This code has been turned off in the non-cc0 case in the
1487 else if (this_is_simplejump
1488 /* Safe to skip USE and CLOBBER insns here
1489 since they will not be deleted. */
1490 && (temp = prev_active_insn (insn))
1491 && no_labels_between_p (temp, insn)
1492 && GET_CODE (temp) == INSN
1493 && GET_CODE (PATTERN (temp)) == SET
1494 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1495 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1496 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1497 /* If we find that the next value tested is `x'
1498 (TEMP1 is the insn where this happens), win. */
1499 && GET_CODE (temp1) == INSN
1500 && GET_CODE (PATTERN (temp1)) == SET
1502 /* Does temp1 `tst' the value of x? */
1503 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1504 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1505 && (temp1 = next_nonnote_insn (temp1))
1507 /* Does temp1 compare the value of x against zero? */
1508 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1509 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1510 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1511 == SET_DEST (PATTERN (temp)))
1512 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1513 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1515 && condjump_p (temp1))
1517 /* Get the if_then_else from the condjump. */
1518 rtx choice = SET_SRC (PATTERN (temp1));
1519 if (GET_CODE (choice) == IF_THEN_ELSE)
1521 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1522 rtx val = SET_SRC (PATTERN (temp));
1524 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1528 if (cond == const_true_rtx)
1529 ultimate = XEXP (choice, 1);
1530 else if (cond == const0_rtx)
1531 ultimate = XEXP (choice, 2);
1535 if (ultimate == pc_rtx)
1536 ultimate = get_label_after (temp1);
1537 else if (ultimate && GET_CODE (ultimate) != RETURN)
1538 ultimate = XEXP (ultimate, 0);
1540 if (ultimate && JUMP_LABEL(insn) != ultimate)
1541 changed |= redirect_jump (insn, ultimate);
1547 /* @@ This needs a bit of work before it will be right.
1549 Any type of comparison can be accepted for the first and
1550 second compare. When rewriting the first jump, we must
1551 compute the what conditions can reach label3, and use the
1552 appropriate code. We can not simply reverse/swap the code
1553 of the first jump. In some cases, the second jump must be
1557 < == converts to > ==
1558 < != converts to == >
1561 If the code is written to only accept an '==' test for the second
1562 compare, then all that needs to be done is to swap the condition
1563 of the first branch.
1565 It is questionable whether we want this optimization anyways,
1566 since if the user wrote code like this because he/she knew that
1567 the jump to label1 is taken most of the time, then rewriting
1568 this gives slower code. */
1569 /* @@ This should call get_condition to find the values being
1570 compared, instead of looking for a COMPARE insn when HAVE_cc0
1571 is not defined. This would allow it to work on the m88k. */
1572 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1573 is not defined and the condition is tested by a separate compare
1574 insn. This is because the code below assumes that the result
1575 of the compare dies in the following branch. */
1577 /* Simplify test a ~= b
1591 where ~= is an inequality, e.g. >, and ~~= is the swapped
1594 We recognize this case scanning backwards.
1596 TEMP is the conditional jump to `label2';
1597 TEMP1 is the test for `a == b';
1598 TEMP2 is the conditional jump to `label1';
1599 TEMP3 is the test for `a ~= b'. */
1600 else if (this_is_simplejump
1601 && (temp = prev_active_insn (insn))
1602 && no_labels_between_p (temp, insn)
1603 && condjump_p (temp)
1604 && (temp1 = prev_active_insn (temp))
1605 && no_labels_between_p (temp1, temp)
1606 && GET_CODE (temp1) == INSN
1607 && GET_CODE (PATTERN (temp1)) == SET
1609 && sets_cc0_p (PATTERN (temp1)) == 1
1611 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1612 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1613 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1615 && (temp2 = prev_active_insn (temp1))
1616 && no_labels_between_p (temp2, temp1)
1617 && condjump_p (temp2)
1618 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1619 && (temp3 = prev_active_insn (temp2))
1620 && no_labels_between_p (temp3, temp2)
1621 && GET_CODE (PATTERN (temp3)) == SET
1622 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1623 SET_DEST (PATTERN (temp1)))
1624 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1625 SET_SRC (PATTERN (temp3)))
1626 && ! inequality_comparisons_p (PATTERN (temp))
1627 && inequality_comparisons_p (PATTERN (temp2)))
1629 rtx fallthrough_label = JUMP_LABEL (temp2);
1631 ++LABEL_NUSES (fallthrough_label);
1632 if (swap_jump (temp2, JUMP_LABEL (insn)))
1638 if (--LABEL_NUSES (fallthrough_label) == 0)
1639 delete_insn (fallthrough_label);
1642 /* Simplify if (...) {... x = 1;} if (x) ...
1644 We recognize this case backwards.
1646 TEMP is the test of `x';
1647 TEMP1 is the assignment to `x' at the end of the
1648 previous statement. */
1649 /* @@ This should call get_condition to find the values being
1650 compared, instead of looking for a COMPARE insn when HAVE_cc0
1651 is not defined. This would allow it to work on the m88k. */
1652 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1653 is not defined and the condition is tested by a separate compare
1654 insn. This is because the code below assumes that the result
1655 of the compare dies in the following branch. */
1657 /* ??? This has to be turned off. The problem is that the
1658 unconditional jump might indirectly end up branching to the
1659 label between TEMP1 and TEMP. We can't detect this, in general,
1660 since it may become a jump to there after further optimizations.
1661 If that jump is done, it will be deleted, so we will retry
1662 this optimization in the next pass, thus an infinite loop.
1664 The present code prevents this by putting the jump after the
1665 label, but this is not logically correct. */
1667 else if (this_is_condjump
1668 /* Safe to skip USE and CLOBBER insns here
1669 since they will not be deleted. */
1670 && (temp = prev_active_insn (insn))
1671 && no_labels_between_p (temp, insn)
1672 && GET_CODE (temp) == INSN
1673 && GET_CODE (PATTERN (temp)) == SET
1675 && sets_cc0_p (PATTERN (temp)) == 1
1676 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1678 /* Temp must be a compare insn, we can not accept a register
1679 to register move here, since it may not be simply a
1681 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1682 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1683 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1684 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1685 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1687 /* May skip USE or CLOBBER insns here
1688 for checking for opportunity, since we
1689 take care of them later. */
1690 && (temp1 = prev_active_insn (temp))
1691 && GET_CODE (temp1) == INSN
1692 && GET_CODE (PATTERN (temp1)) == SET
1694 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1696 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1697 == SET_DEST (PATTERN (temp1)))
1699 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1700 /* If this isn't true, cse will do the job. */
1701 && ! no_labels_between_p (temp1, temp))
1703 /* Get the if_then_else from the condjump. */
1704 rtx choice = SET_SRC (PATTERN (insn));
1705 if (GET_CODE (choice) == IF_THEN_ELSE
1706 && (GET_CODE (XEXP (choice, 0)) == EQ
1707 || GET_CODE (XEXP (choice, 0)) == NE))
1709 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1714 /* Get the place that condjump will jump to
1715 if it is reached from here. */
1716 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1718 ultimate = XEXP (choice, 1);
1720 ultimate = XEXP (choice, 2);
1721 /* Get it as a CODE_LABEL. */
1722 if (ultimate == pc_rtx)
1723 ultimate = get_label_after (insn);
1725 /* Get the label out of the LABEL_REF. */
1726 ultimate = XEXP (ultimate, 0);
1728 /* Insert the jump immediately before TEMP, specifically
1729 after the label that is between TEMP1 and TEMP. */
1730 last_insn = PREV_INSN (temp);
1732 /* If we would be branching to the next insn, the jump
1733 would immediately be deleted and the re-inserted in
1734 a subsequent pass over the code. So don't do anything
1736 if (next_active_insn (last_insn)
1737 != next_active_insn (ultimate))
1739 emit_barrier_after (last_insn);
1740 p = emit_jump_insn_after (gen_jump (ultimate),
1742 JUMP_LABEL (p) = ultimate;
1743 ++LABEL_NUSES (ultimate);
1744 if (INSN_UID (ultimate) < max_jump_chain
1745 && INSN_CODE (p) < max_jump_chain)
1747 jump_chain[INSN_UID (p)]
1748 = jump_chain[INSN_UID (ultimate)];
1749 jump_chain[INSN_UID (ultimate)] = p;
1757 /* Detect a conditional jump going to the same place
1758 as an immediately following unconditional jump. */
1759 else if (this_is_condjump
1760 && (temp = next_active_insn (insn)) != 0
1761 && simplejump_p (temp)
1762 && (next_active_insn (JUMP_LABEL (insn))
1763 == next_active_insn (JUMP_LABEL (temp))))
1769 /* Detect a conditional jump jumping over an unconditional jump. */
1771 else if ((this_is_condjump || this_is_condjump_in_parallel)
1772 && ! this_is_simplejump
1773 && reallabelprev != 0
1774 && GET_CODE (reallabelprev) == JUMP_INSN
1775 && prev_active_insn (reallabelprev) == insn
1776 && no_labels_between_p (insn, reallabelprev)
1777 && simplejump_p (reallabelprev))
1779 /* When we invert the unconditional jump, we will be
1780 decrementing the usage count of its old label.
1781 Make sure that we don't delete it now because that
1782 might cause the following code to be deleted. */
1783 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1784 rtx prev_label = JUMP_LABEL (insn);
1787 ++LABEL_NUSES (prev_label);
1789 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1791 /* It is very likely that if there are USE insns before
1792 this jump, they hold REG_DEAD notes. These REG_DEAD
1793 notes are no longer valid due to this optimization,
1794 and will cause the life-analysis that following passes
1795 (notably delayed-branch scheduling) to think that
1796 these registers are dead when they are not.
1798 To prevent this trouble, we just remove the USE insns
1799 from the insn chain. */
1801 while (prev_uses && GET_CODE (prev_uses) == INSN
1802 && GET_CODE (PATTERN (prev_uses)) == USE)
1804 rtx useless = prev_uses;
1805 prev_uses = prev_nonnote_insn (prev_uses);
1806 delete_insn (useless);
1809 delete_insn (reallabelprev);
1814 /* We can now safely delete the label if it is unreferenced
1815 since the delete_insn above has deleted the BARRIER. */
1816 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1817 delete_insn (prev_label);
1822 /* Detect a jump to a jump. */
1824 nlabel = follow_jumps (JUMP_LABEL (insn));
1825 if (nlabel != JUMP_LABEL (insn)
1826 && redirect_jump (insn, nlabel))
1832 /* Look for if (foo) bar; else break; */
1833 /* The insns look like this:
1834 insn = condjump label1;
1835 ...range1 (some insns)...
1838 ...range2 (some insns)...
1839 jump somewhere unconditionally
1842 rtx label1 = next_label (insn);
1843 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1844 /* Don't do this optimization on the first round, so that
1845 jump-around-a-jump gets simplified before we ask here
1846 whether a jump is unconditional.
1848 Also don't do it when we are called after reload since
1849 it will confuse reorg. */
1851 && (reload_completed ? ! flag_delayed_branch : 1)
1852 /* Make sure INSN is something we can invert. */
1853 && condjump_p (insn)
1855 && JUMP_LABEL (insn) == label1
1856 && LABEL_NUSES (label1) == 1
1857 && GET_CODE (range1end) == JUMP_INSN
1858 && simplejump_p (range1end))
1860 rtx label2 = next_label (label1);
1861 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1862 if (range1end != range2end
1863 && JUMP_LABEL (range1end) == label2
1864 && GET_CODE (range2end) == JUMP_INSN
1865 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1866 /* Invert the jump condition, so we
1867 still execute the same insns in each case. */
1868 && invert_jump (insn, label1))
1870 rtx range1beg = next_active_insn (insn);
1871 rtx range2beg = next_active_insn (label1);
1872 rtx range1after, range2after;
1873 rtx range1before, range2before;
1876 /* Include in each range any notes before it, to be
1877 sure that we get the line number note if any, even
1878 if there are other notes here. */
1879 while (PREV_INSN (range1beg)
1880 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1881 range1beg = PREV_INSN (range1beg);
1883 while (PREV_INSN (range2beg)
1884 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1885 range2beg = PREV_INSN (range2beg);
1887 /* Don't move NOTEs for blocks or loops; shift them
1888 outside the ranges, where they'll stay put. */
1889 range1beg = squeeze_notes (range1beg, range1end);
1890 range2beg = squeeze_notes (range2beg, range2end);
1892 /* Get current surrounds of the 2 ranges. */
1893 range1before = PREV_INSN (range1beg);
1894 range2before = PREV_INSN (range2beg);
1895 range1after = NEXT_INSN (range1end);
1896 range2after = NEXT_INSN (range2end);
1898 /* Splice range2 where range1 was. */
1899 NEXT_INSN (range1before) = range2beg;
1900 PREV_INSN (range2beg) = range1before;
1901 NEXT_INSN (range2end) = range1after;
1902 PREV_INSN (range1after) = range2end;
1903 /* Splice range1 where range2 was. */
1904 NEXT_INSN (range2before) = range1beg;
1905 PREV_INSN (range1beg) = range2before;
1906 NEXT_INSN (range1end) = range2after;
1907 PREV_INSN (range2after) = range1end;
1909 /* Check for a loop end note between the end of
1910 range2, and the next code label. If there is one,
1911 then what we have really seen is
1912 if (foo) break; end_of_loop;
1913 and moved the break sequence outside the loop.
1914 We must move the LOOP_END note to where the
1915 loop really ends now, or we will confuse loop
1916 optimization. Stop if we find a LOOP_BEG note
1917 first, since we don't want to move the LOOP_END
1918 note in that case. */
1919 for (;range2after != label2; range2after = rangenext)
1921 rangenext = NEXT_INSN (range2after);
1922 if (GET_CODE (range2after) == NOTE)
1924 if (NOTE_LINE_NUMBER (range2after)
1925 == NOTE_INSN_LOOP_END)
1927 NEXT_INSN (PREV_INSN (range2after))
1929 PREV_INSN (rangenext)
1930 = PREV_INSN (range2after);
1931 PREV_INSN (range2after)
1932 = PREV_INSN (range1beg);
1933 NEXT_INSN (range2after) = range1beg;
1934 NEXT_INSN (PREV_INSN (range1beg))
1936 PREV_INSN (range1beg) = range2after;
1938 else if (NOTE_LINE_NUMBER (range2after)
1939 == NOTE_INSN_LOOP_BEG)
1949 /* Now that the jump has been tensioned,
1950 try cross jumping: check for identical code
1951 before the jump and before its target label. */
1953 /* First, cross jumping of conditional jumps: */
1955 if (cross_jump && condjump_p (insn))
1957 rtx newjpos, newlpos;
1958 rtx x = prev_real_insn (JUMP_LABEL (insn));
1960 /* A conditional jump may be crossjumped
1961 only if the place it jumps to follows
1962 an opposing jump that comes back here. */
1964 if (x != 0 && ! jump_back_p (x, insn))
1965 /* We have no opposing jump;
1966 cannot cross jump this insn. */
1970 /* TARGET is nonzero if it is ok to cross jump
1971 to code before TARGET. If so, see if matches. */
1973 find_cross_jump (insn, x, 2,
1974 &newjpos, &newlpos);
1978 do_cross_jump (insn, newjpos, newlpos);
1979 /* Make the old conditional jump
1980 into an unconditional one. */
1981 SET_SRC (PATTERN (insn))
1982 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
1983 INSN_CODE (insn) = -1;
1984 emit_barrier_after (insn);
1985 /* Add to jump_chain unless this is a new label
1986 whose UID is too large. */
1987 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1989 jump_chain[INSN_UID (insn)]
1990 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1991 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1998 /* Cross jumping of unconditional jumps:
1999 a few differences. */
2001 if (cross_jump && simplejump_p (insn))
2003 rtx newjpos, newlpos;
2008 /* TARGET is nonzero if it is ok to cross jump
2009 to code before TARGET. If so, see if matches. */
2010 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2011 &newjpos, &newlpos);
2013 /* If cannot cross jump to code before the label,
2014 see if we can cross jump to another jump to
2016 /* Try each other jump to this label. */
2017 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2018 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2019 target != 0 && newjpos == 0;
2020 target = jump_chain[INSN_UID (target)])
2022 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2023 /* Ignore TARGET if it's deleted. */
2024 && ! INSN_DELETED_P (target))
2025 find_cross_jump (insn, target, 2,
2026 &newjpos, &newlpos);
2030 do_cross_jump (insn, newjpos, newlpos);
2036 /* This code was dead in the previous jump.c! */
2037 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2039 /* Return insns all "jump to the same place"
2040 so we can cross-jump between any two of them. */
2042 rtx newjpos, newlpos, target;
2046 /* If cannot cross jump to code before the label,
2047 see if we can cross jump to another jump to
2049 /* Try each other jump to this label. */
2050 for (target = jump_chain[0];
2051 target != 0 && newjpos == 0;
2052 target = jump_chain[INSN_UID (target)])
2054 && ! INSN_DELETED_P (target)
2055 && GET_CODE (PATTERN (target)) == RETURN)
2056 find_cross_jump (insn, target, 2,
2057 &newjpos, &newlpos);
2061 do_cross_jump (insn, newjpos, newlpos);
2072 /* Delete extraneous line number notes.
2073 Note that two consecutive notes for different lines are not really
2074 extraneous. There should be some indication where that line belonged,
2075 even if it became empty. */
2080 for (insn = f; insn; insn = NEXT_INSN (insn))
2081 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2083 /* Delete this note if it is identical to previous note. */
2085 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2086 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2099 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2100 in front of it. If the machine allows it at this point (we might be
2101 after reload for a leaf routine), it will improve optimization for it
2102 to be there. We do this both here and at the start of this pass since
2103 the RETURN might have been deleted by some of our optimizations. */
2104 insn = get_last_insn ();
2105 while (insn && GET_CODE (insn) == NOTE)
2106 insn = PREV_INSN (insn);
2108 if (insn && GET_CODE (insn) != BARRIER)
2110 emit_jump_insn (gen_return ());
2116 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2117 If so, delete it, and record that this function can drop off the end. */
2123 /* One label can follow the end-note: the return label. */
2124 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2125 /* Ordinary insns can follow it if returning a structure. */
2126 || GET_CODE (insn) == INSN
2127 /* If machine uses explicit RETURN insns, no epilogue,
2128 then one of them follows the note. */
2129 || (GET_CODE (insn) == JUMP_INSN
2130 && GET_CODE (PATTERN (insn)) == RETURN)
2131 /* A barrier can follow the return insn. */
2132 || GET_CODE (insn) == BARRIER
2133 /* Other kinds of notes can follow also. */
2134 || (GET_CODE (insn) == NOTE
2135 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2136 insn = PREV_INSN (insn);
2139 /* Report if control can fall through at the end of the function. */
2140 if (insn && GET_CODE (insn) == NOTE
2141 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2147 /* Show JUMP_CHAIN no longer valid. */
2151 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2152 jump. Assume that this unconditional jump is to the exit test code. If
2153 the code is sufficiently simple, make a copy of it before INSN,
2154 followed by a jump to the exit of the loop. Then delete the unconditional
2157 Return 1 if we made the change, else 0.
2159 This is only safe immediately after a regscan pass because it uses the
2160 values of regno_first_uid and regno_last_uid. */
2163 duplicate_loop_exit_test (loop_start)
2166 rtx insn, set, reg, p, link;
2169 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2171 int max_reg = max_reg_num ();
2174 /* Scan the exit code. We do not perform this optimization if any insn:
2178 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2179 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2180 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2183 Also, don't do this if the exit code is more than 20 insns. */
2185 for (insn = exitcode;
2187 && ! (GET_CODE (insn) == NOTE
2188 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2189 insn = NEXT_INSN (insn))
2191 switch (GET_CODE (insn))
2197 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2198 a jump immediately after the loop start that branches outside
2199 the loop but within an outer loop, near the exit test.
2200 If we copied this exit test and created a phony
2201 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2202 before the exit test look like these could be safely moved
2203 out of the loop even if they actually may be never executed.
2204 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2206 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2207 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2208 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2209 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2214 if (++num_insns > 20
2215 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2216 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2222 /* Unless INSN is zero, we can do the optimization. */
2228 /* See if any insn sets a register only used in the loop exit code and
2229 not a user variable. If so, replace it with a new register. */
2230 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2231 if (GET_CODE (insn) == INSN
2232 && (set = single_set (insn)) != 0
2233 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2234 || (GET_CODE (reg) == SUBREG
2235 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2236 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2237 && regno_first_uid[REGNO (reg)] == INSN_UID (insn))
2239 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2240 if (regno_last_uid[REGNO (reg)] == INSN_UID (p))
2245 /* We can do the replacement. Allocate reg_map if this is the
2246 first replacement we found. */
2249 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2250 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2253 REG_LOOP_TEST_P (reg) = 1;
2255 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2259 /* Now copy each insn. */
2260 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2261 switch (GET_CODE (insn))
2264 copy = emit_barrier_before (loop_start);
2267 /* Only copy line-number notes. */
2268 if (NOTE_LINE_NUMBER (insn) >= 0)
2270 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2271 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2276 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2278 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2280 mark_jump_label (PATTERN (copy), copy, 0);
2282 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2284 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2285 if (REG_NOTE_KIND (link) != REG_LABEL)
2287 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
2288 XEXP (link, 0), REG_NOTES (copy)));
2289 if (reg_map && REG_NOTES (copy))
2290 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2294 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2296 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2297 mark_jump_label (PATTERN (copy), copy, 0);
2298 if (REG_NOTES (insn))
2300 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2302 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2305 /* If this is a simple jump, add it to the jump chain. */
2307 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2308 && simplejump_p (copy))
2310 jump_chain[INSN_UID (copy)]
2311 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2312 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2320 /* Now clean up by emitting a jump to the end label and deleting the jump
2321 at the start of the loop. */
2322 if (! copy || GET_CODE (copy) != BARRIER)
2324 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2326 mark_jump_label (PATTERN (copy), copy, 0);
2327 if (INSN_UID (copy) < max_jump_chain
2328 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2330 jump_chain[INSN_UID (copy)]
2331 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2332 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2334 emit_barrier_before (loop_start);
2337 /* Mark the exit code as the virtual top of the converted loop. */
2338 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2340 delete_insn (next_nonnote_insn (loop_start));
2345 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2346 loop-end notes between START and END out before START. Assume that
2347 END is not such a note. START may be such a note. Returns the value
2348 of the new starting insn, which may be different if the original start
2352 squeeze_notes (start, end)
2358 for (insn = start; insn != end; insn = next)
2360 next = NEXT_INSN (insn);
2361 if (GET_CODE (insn) == NOTE
2362 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2363 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2364 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2365 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2366 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2367 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2373 rtx prev = PREV_INSN (insn);
2374 PREV_INSN (insn) = PREV_INSN (start);
2375 NEXT_INSN (insn) = start;
2376 NEXT_INSN (PREV_INSN (insn)) = insn;
2377 PREV_INSN (NEXT_INSN (insn)) = insn;
2378 NEXT_INSN (prev) = next;
2379 PREV_INSN (next) = prev;
2387 /* Compare the instructions before insn E1 with those before E2
2388 to find an opportunity for cross jumping.
2389 (This means detecting identical sequences of insns followed by
2390 jumps to the same place, or followed by a label and a jump
2391 to that label, and replacing one with a jump to the other.)
2393 Assume E1 is a jump that jumps to label E2
2394 (that is not always true but it might as well be).
2395 Find the longest possible equivalent sequences
2396 and store the first insns of those sequences into *F1 and *F2.
2397 Store zero there if no equivalent preceding instructions are found.
2399 We give up if we find a label in stream 1.
2400 Actually we could transfer that label into stream 2. */
2403 find_cross_jump (e1, e2, minimum, f1, f2)
2408 register rtx i1 = e1, i2 = e2;
2409 register rtx p1, p2;
2412 rtx last1 = 0, last2 = 0;
2413 rtx afterlast1 = 0, afterlast2 = 0;
2421 i1 = prev_nonnote_insn (i1);
2423 i2 = PREV_INSN (i2);
2424 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2425 i2 = PREV_INSN (i2);
2430 /* Don't allow the range of insns preceding E1 or E2
2431 to include the other (E2 or E1). */
2432 if (i2 == e1 || i1 == e2)
2435 /* If we will get to this code by jumping, those jumps will be
2436 tensioned to go directly to the new label (before I2),
2437 so this cross-jumping won't cost extra. So reduce the minimum. */
2438 if (GET_CODE (i1) == CODE_LABEL)
2444 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2450 /* If this is a CALL_INSN, compare register usage information.
2451 If we don't check this on stack register machines, the two
2452 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2453 numbers of stack registers in the same basic block.
2454 If we don't check this on machines with delay slots, a delay slot may
2455 be filled that clobbers a parameter expected by the subroutine.
2457 ??? We take the simple route for now and assume that if they're
2458 equal, they were constructed identically. */
2460 if (GET_CODE (i1) == CALL_INSN
2461 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2462 CALL_INSN_FUNCTION_USAGE (i2)))
2466 /* If cross_jump_death_matters is not 0, the insn's mode
2467 indicates whether or not the insn contains any stack-like
2470 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2472 /* If register stack conversion has already been done, then
2473 death notes must also be compared before it is certain that
2474 the two instruction streams match. */
2477 HARD_REG_SET i1_regset, i2_regset;
2479 CLEAR_HARD_REG_SET (i1_regset);
2480 CLEAR_HARD_REG_SET (i2_regset);
2482 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2483 if (REG_NOTE_KIND (note) == REG_DEAD
2484 && STACK_REG_P (XEXP (note, 0)))
2485 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2487 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2488 if (REG_NOTE_KIND (note) == REG_DEAD
2489 && STACK_REG_P (XEXP (note, 0)))
2490 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2492 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2501 if (lose || GET_CODE (p1) != GET_CODE (p2)
2502 || ! rtx_renumbered_equal_p (p1, p2))
2504 /* The following code helps take care of G++ cleanups. */
2508 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2509 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2510 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2511 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2512 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2513 /* If the equivalences are not to a constant, they may
2514 reference pseudos that no longer exist, so we can't
2516 && CONSTANT_P (XEXP (equiv1, 0))
2517 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2519 rtx s1 = single_set (i1);
2520 rtx s2 = single_set (i2);
2521 if (s1 != 0 && s2 != 0
2522 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2524 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2525 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2526 if (! rtx_renumbered_equal_p (p1, p2))
2528 else if (apply_change_group ())
2533 /* Insns fail to match; cross jumping is limited to the following
2537 /* Don't allow the insn after a compare to be shared by
2538 cross-jumping unless the compare is also shared.
2539 Here, if either of these non-matching insns is a compare,
2540 exclude the following insn from possible cross-jumping. */
2541 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2542 last1 = afterlast1, last2 = afterlast2, ++minimum;
2545 /* If cross-jumping here will feed a jump-around-jump
2546 optimization, this jump won't cost extra, so reduce
2548 if (GET_CODE (i1) == JUMP_INSN
2550 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2556 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2558 /* Ok, this insn is potentially includable in a cross-jump here. */
2559 afterlast1 = last1, afterlast2 = last2;
2560 last1 = i1, last2 = i2, --minimum;
2564 if (minimum <= 0 && last1 != 0 && last1 != e1)
2565 *f1 = last1, *f2 = last2;
2569 do_cross_jump (insn, newjpos, newlpos)
2570 rtx insn, newjpos, newlpos;
2572 /* Find an existing label at this point
2573 or make a new one if there is none. */
2574 register rtx label = get_label_before (newlpos);
2576 /* Make the same jump insn jump to the new point. */
2577 if (GET_CODE (PATTERN (insn)) == RETURN)
2579 /* Remove from jump chain of returns. */
2580 delete_from_jump_chain (insn);
2581 /* Change the insn. */
2582 PATTERN (insn) = gen_jump (label);
2583 INSN_CODE (insn) = -1;
2584 JUMP_LABEL (insn) = label;
2585 LABEL_NUSES (label)++;
2586 /* Add to new the jump chain. */
2587 if (INSN_UID (label) < max_jump_chain
2588 && INSN_UID (insn) < max_jump_chain)
2590 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2591 jump_chain[INSN_UID (label)] = insn;
2595 redirect_jump (insn, label);
2597 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2598 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2599 the NEWJPOS stream. */
2601 while (newjpos != insn)
2605 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2606 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2607 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2608 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2609 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2610 remove_note (newlpos, lnote);
2612 delete_insn (newjpos);
2613 newjpos = next_real_insn (newjpos);
2614 newlpos = next_real_insn (newlpos);
2618 /* Return the label before INSN, or put a new label there. */
2621 get_label_before (insn)
2626 /* Find an existing label at this point
2627 or make a new one if there is none. */
2628 label = prev_nonnote_insn (insn);
2630 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2632 rtx prev = PREV_INSN (insn);
2634 label = gen_label_rtx ();
2635 emit_label_after (label, prev);
2636 LABEL_NUSES (label) = 0;
2641 /* Return the label after INSN, or put a new label there. */
2644 get_label_after (insn)
2649 /* Find an existing label at this point
2650 or make a new one if there is none. */
2651 label = next_nonnote_insn (insn);
2653 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2655 label = gen_label_rtx ();
2656 emit_label_after (label, insn);
2657 LABEL_NUSES (label) = 0;
2662 /* Return 1 if INSN is a jump that jumps to right after TARGET
2663 only on the condition that TARGET itself would drop through.
2664 Assumes that TARGET is a conditional jump. */
2667 jump_back_p (insn, target)
2671 enum rtx_code codei, codet;
2673 if (simplejump_p (insn) || ! condjump_p (insn)
2674 || simplejump_p (target)
2675 || target != prev_real_insn (JUMP_LABEL (insn)))
2678 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2679 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2681 codei = GET_CODE (cinsn);
2682 codet = GET_CODE (ctarget);
2684 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2686 if (! can_reverse_comparison_p (cinsn, insn))
2688 codei = reverse_condition (codei);
2691 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2693 if (! can_reverse_comparison_p (ctarget, target))
2695 codet = reverse_condition (codet);
2698 return (codei == codet
2699 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2700 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2703 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2704 return non-zero if it is safe to reverse this comparison. It is if our
2705 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2706 this is known to be an integer comparison. */
2709 can_reverse_comparison_p (comparison, insn)
2715 /* If this is not actually a comparison, we can't reverse it. */
2716 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2719 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2720 /* If this is an NE comparison, it is safe to reverse it to an EQ
2721 comparison and vice versa, even for floating point. If no operands
2722 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2723 always false and NE is always true, so the reversal is also valid. */
2725 || GET_CODE (comparison) == NE
2726 || GET_CODE (comparison) == EQ)
2729 arg0 = XEXP (comparison, 0);
2731 /* Make sure ARG0 is one of the actual objects being compared. If we
2732 can't do this, we can't be sure the comparison can be reversed.
2734 Handle cc0 and a MODE_CC register. */
2735 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2741 rtx prev = prev_nonnote_insn (insn);
2742 rtx set = single_set (prev);
2744 if (set == 0 || SET_DEST (set) != arg0)
2747 arg0 = SET_SRC (set);
2749 if (GET_CODE (arg0) == COMPARE)
2750 arg0 = XEXP (arg0, 0);
2753 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2754 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2755 return (GET_CODE (arg0) == CONST_INT
2756 || (GET_MODE (arg0) != VOIDmode
2757 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2758 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2761 /* Given an rtx-code for a comparison, return the code
2762 for the negated comparison.
2763 WATCH OUT! reverse_condition is not safe to use on a jump
2764 that might be acting on the results of an IEEE floating point comparison,
2765 because of the special treatment of non-signaling nans in comparisons.
2766 Use can_reverse_comparison_p to be sure. */
2769 reverse_condition (code)
2810 /* Similar, but return the code when two operands of a comparison are swapped.
2811 This IS safe for IEEE floating-point. */
2814 swap_condition (code)
2853 /* Given a comparison CODE, return the corresponding unsigned comparison.
2854 If CODE is an equality comparison or already an unsigned comparison,
2855 CODE is returned. */
2858 unsigned_condition (code)
2888 /* Similarly, return the signed version of a comparison. */
2891 signed_condition (code)
2921 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2922 truth of CODE1 implies the truth of CODE2. */
2925 comparison_dominates_p (code1, code2)
2926 enum rtx_code code1, code2;
2934 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
2939 if (code2 == LE || code2 == NE)
2944 if (code2 == GE || code2 == NE)
2949 if (code2 == LEU || code2 == NE)
2954 if (code2 == GEU || code2 == NE)
2962 /* Return 1 if INSN is an unconditional jump and nothing else. */
2968 return (GET_CODE (insn) == JUMP_INSN
2969 && GET_CODE (PATTERN (insn)) == SET
2970 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2971 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2974 /* Return nonzero if INSN is a (possibly) conditional jump
2975 and nothing more. */
2981 register rtx x = PATTERN (insn);
2982 if (GET_CODE (x) != SET)
2984 if (GET_CODE (SET_DEST (x)) != PC)
2986 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2988 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2990 if (XEXP (SET_SRC (x), 2) == pc_rtx
2991 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2992 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2994 if (XEXP (SET_SRC (x), 1) == pc_rtx
2995 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2996 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3001 /* Return nonzero if INSN is a (possibly) conditional jump
3002 and nothing more. */
3005 condjump_in_parallel_p (insn)
3008 register rtx x = PATTERN (insn);
3010 if (GET_CODE (x) != PARALLEL)
3013 x = XVECEXP (x, 0, 0);
3015 if (GET_CODE (x) != SET)
3017 if (GET_CODE (SET_DEST (x)) != PC)
3019 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3021 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3023 if (XEXP (SET_SRC (x), 2) == pc_rtx
3024 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3025 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3027 if (XEXP (SET_SRC (x), 1) == pc_rtx
3028 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3029 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3034 /* Return 1 if X is an RTX that does nothing but set the condition codes
3035 and CLOBBER or USE registers.
3036 Return -1 if X does explicitly set the condition codes,
3037 but also does other things. */
3044 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3046 if (GET_CODE (x) == PARALLEL)
3050 int other_things = 0;
3051 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3053 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3054 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3056 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3059 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3067 /* Follow any unconditional jump at LABEL;
3068 return the ultimate label reached by any such chain of jumps.
3069 If LABEL is not followed by a jump, return LABEL.
3070 If the chain loops or we can't find end, return LABEL,
3071 since that tells caller to avoid changing the insn.
3073 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3074 a USE or CLOBBER. */
3077 follow_jumps (label)
3082 register rtx value = label;
3087 && (insn = next_active_insn (value)) != 0
3088 && GET_CODE (insn) == JUMP_INSN
3089 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3090 || GET_CODE (PATTERN (insn)) == RETURN)
3091 && (next = NEXT_INSN (insn))
3092 && GET_CODE (next) == BARRIER);
3095 /* Don't chain through the insn that jumps into a loop
3096 from outside the loop,
3097 since that would create multiple loop entry jumps
3098 and prevent loop optimization. */
3100 if (!reload_completed)
3101 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3102 if (GET_CODE (tem) == NOTE
3103 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
3106 /* If we have found a cycle, make the insn jump to itself. */
3107 if (JUMP_LABEL (insn) == label)
3110 tem = next_active_insn (JUMP_LABEL (insn));
3111 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3112 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3115 value = JUMP_LABEL (insn);
3122 /* Assuming that field IDX of X is a vector of label_refs,
3123 replace each of them by the ultimate label reached by it.
3124 Return nonzero if a change is made.
3125 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3128 tension_vector_labels (x, idx)
3134 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3136 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3137 register rtx nlabel = follow_jumps (olabel);
3138 if (nlabel && nlabel != olabel)
3140 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3141 ++LABEL_NUSES (nlabel);
3142 if (--LABEL_NUSES (olabel) == 0)
3143 delete_insn (olabel);
3150 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3151 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3152 in INSN, then store one of them in JUMP_LABEL (INSN).
3153 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3154 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3155 Also, when there are consecutive labels, canonicalize on the last of them.
3157 Note that two labels separated by a loop-beginning note
3158 must be kept distinct if we have not yet done loop-optimization,
3159 because the gap between them is where loop-optimize
3160 will want to move invariant code to. CROSS_JUMP tells us
3161 that loop-optimization is done with.
3163 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3164 two labels distinct if they are separated by only USE or CLOBBER insns. */
3167 mark_jump_label (x, insn, cross_jump)
3172 register RTX_CODE code = GET_CODE (x);
3190 /* If this is a constant-pool reference, see if it is a label. */
3191 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3192 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3193 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3198 rtx label = XEXP (x, 0);
3203 if (GET_CODE (label) != CODE_LABEL)
3206 /* Ignore references to labels of containing functions. */
3207 if (LABEL_REF_NONLOCAL_P (x))
3210 /* If there are other labels following this one,
3211 replace it with the last of the consecutive labels. */
3212 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3214 if (GET_CODE (next) == CODE_LABEL)
3216 else if (cross_jump && GET_CODE (next) == INSN
3217 && (GET_CODE (PATTERN (next)) == USE
3218 || GET_CODE (PATTERN (next)) == CLOBBER))
3220 else if (GET_CODE (next) != NOTE)
3222 else if (! cross_jump
3223 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3224 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
3228 XEXP (x, 0) = label;
3229 ++LABEL_NUSES (label);
3233 if (GET_CODE (insn) == JUMP_INSN)
3234 JUMP_LABEL (insn) = label;
3236 /* If we've changed OLABEL and we had a REG_LABEL note
3237 for it, update it as well. */
3238 else if (label != olabel
3239 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3240 XEXP (note, 0) = label;
3242 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3244 else if (! find_reg_note (insn, REG_LABEL, label))
3246 rtx next = next_real_insn (label);
3247 /* Don't record labels that refer to dispatch tables.
3248 This is not necessary, since the tablejump
3249 references the same label.
3250 And if we did record them, flow.c would make worse code. */
3252 || ! (GET_CODE (next) == JUMP_INSN
3253 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3254 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
3255 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
3262 /* Do walk the labels in a vector, but not the first operand of an
3263 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3267 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3269 for (i = 0; i < XVECLEN (x, eltnum); i++)
3270 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3275 fmt = GET_RTX_FORMAT (code);
3276 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3279 mark_jump_label (XEXP (x, i), insn, cross_jump);
3280 else if (fmt[i] == 'E')
3283 for (j = 0; j < XVECLEN (x, i); j++)
3284 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3289 /* If all INSN does is set the pc, delete it,
3290 and delete the insn that set the condition codes for it
3291 if that's what the previous thing was. */
3297 register rtx set = single_set (insn);
3299 if (set && GET_CODE (SET_DEST (set)) == PC)
3300 delete_computation (insn);
3303 /* Delete INSN and recursively delete insns that compute values used only
3304 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3305 If we are running before flow.c, we need do nothing since flow.c will
3306 delete dead code. We also can't know if the registers being used are
3307 dead or not at this point.
3309 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3310 nothing other than set a register that dies in this insn, we can delete
3313 On machines with CC0, if CC0 is used in this insn, we may be able to
3314 delete the insn that set it. */
3317 delete_computation (insn)
3323 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3325 rtx prev = prev_nonnote_insn (insn);
3326 /* We assume that at this stage
3327 CC's are always set explicitly
3328 and always immediately before the jump that
3329 will use them. So if the previous insn
3330 exists to set the CC's, delete it
3331 (unless it performs auto-increments, etc.). */
3332 if (prev && GET_CODE (prev) == INSN
3333 && sets_cc0_p (PATTERN (prev)))
3335 if (sets_cc0_p (PATTERN (prev)) > 0
3336 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3337 delete_computation (prev);
3339 /* Otherwise, show that cc0 won't be used. */
3340 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
3341 cc0_rtx, REG_NOTES (prev));
3346 for (note = REG_NOTES (insn); note; note = next)
3350 next = XEXP (note, 1);
3352 if (REG_NOTE_KIND (note) != REG_DEAD
3353 /* Verify that the REG_NOTE is legitimate. */
3354 || GET_CODE (XEXP (note, 0)) != REG)
3357 for (our_prev = prev_nonnote_insn (insn);
3358 our_prev && GET_CODE (our_prev) == INSN;
3359 our_prev = prev_nonnote_insn (our_prev))
3361 /* If we reach a SEQUENCE, it is too complex to try to
3362 do anything with it, so give up. */
3363 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3366 if (GET_CODE (PATTERN (our_prev)) == USE
3367 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3368 /* reorg creates USEs that look like this. We leave them
3369 alone because reorg needs them for its own purposes. */
3372 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3374 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3377 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3379 /* If we find a SET of something else, we can't
3384 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3386 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3388 if (GET_CODE (part) == SET
3389 && SET_DEST (part) != XEXP (note, 0))
3393 if (i == XVECLEN (PATTERN (our_prev), 0))
3394 delete_computation (our_prev);
3396 else if (GET_CODE (PATTERN (our_prev)) == SET
3397 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3398 delete_computation (our_prev);
3403 /* If OUR_PREV references the register that dies here, it is an
3404 additional use. Hence any prior SET isn't dead. However, this
3405 insn becomes the new place for the REG_DEAD note. */
3406 if (reg_overlap_mentioned_p (XEXP (note, 0),
3407 PATTERN (our_prev)))
3409 XEXP (note, 1) = REG_NOTES (our_prev);
3410 REG_NOTES (our_prev) = note;
3419 /* Delete insn INSN from the chain of insns and update label ref counts.
3420 May delete some following insns as a consequence; may even delete
3421 a label elsewhere and insns that follow it.
3423 Returns the first insn after INSN that was not deleted. */
3429 register rtx next = NEXT_INSN (insn);
3430 register rtx prev = PREV_INSN (insn);
3431 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3432 register int dont_really_delete = 0;
3434 while (next && INSN_DELETED_P (next))
3435 next = NEXT_INSN (next);
3437 /* This insn is already deleted => return first following nondeleted. */
3438 if (INSN_DELETED_P (insn))
3441 /* Don't delete user-declared labels. Convert them to special NOTEs
3443 if (was_code_label && LABEL_NAME (insn) != 0
3444 && optimize && ! dont_really_delete)
3446 PUT_CODE (insn, NOTE);
3447 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3448 NOTE_SOURCE_FILE (insn) = 0;
3449 dont_really_delete = 1;
3452 /* Mark this insn as deleted. */
3453 INSN_DELETED_P (insn) = 1;
3455 /* If this is an unconditional jump, delete it from the jump chain. */
3456 if (simplejump_p (insn))
3457 delete_from_jump_chain (insn);
3459 /* If instruction is followed by a barrier,
3460 delete the barrier too. */
3462 if (next != 0 && GET_CODE (next) == BARRIER)
3464 INSN_DELETED_P (next) = 1;
3465 next = NEXT_INSN (next);
3468 /* Patch out INSN (and the barrier if any) */
3470 if (optimize && ! dont_really_delete)
3474 NEXT_INSN (prev) = next;
3475 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3476 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3477 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3482 PREV_INSN (next) = prev;
3483 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3484 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3487 if (prev && NEXT_INSN (prev) == 0)
3488 set_last_insn (prev);
3491 /* If deleting a jump, decrement the count of the label,
3492 and delete the label if it is now unused. */
3494 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3495 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3497 /* This can delete NEXT or PREV,
3498 either directly if NEXT is JUMP_LABEL (INSN),
3499 or indirectly through more levels of jumps. */
3500 delete_insn (JUMP_LABEL (insn));
3501 /* I feel a little doubtful about this loop,
3502 but I see no clean and sure alternative way
3503 to find the first insn after INSN that is not now deleted.
3504 I hope this works. */
3505 while (next && INSN_DELETED_P (next))
3506 next = NEXT_INSN (next);
3510 /* Likewise if we're deleting a dispatch table. */
3512 if (GET_CODE (insn) == JUMP_INSN
3513 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3514 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3516 rtx pat = PATTERN (insn);
3517 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3518 int len = XVECLEN (pat, diff_vec_p);
3520 for (i = 0; i < len; i++)
3521 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3522 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3523 while (next && INSN_DELETED_P (next))
3524 next = NEXT_INSN (next);
3528 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3529 prev = PREV_INSN (prev);
3531 /* If INSN was a label and a dispatch table follows it,
3532 delete the dispatch table. The tablejump must have gone already.
3533 It isn't useful to fall through into a table. */
3536 && NEXT_INSN (insn) != 0
3537 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3538 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3539 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3540 next = delete_insn (NEXT_INSN (insn));
3542 /* If INSN was a label, delete insns following it if now unreachable. */
3544 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3546 register RTX_CODE code;
3548 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3549 || code == NOTE || code == BARRIER
3550 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3553 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3554 next = NEXT_INSN (next);
3555 /* Keep going past other deleted labels to delete what follows. */
3556 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3557 next = NEXT_INSN (next);
3559 /* Note: if this deletes a jump, it can cause more
3560 deletion of unreachable code, after a different label.
3561 As long as the value from this recursive call is correct,
3562 this invocation functions correctly. */
3563 next = delete_insn (next);
3570 /* Advance from INSN till reaching something not deleted
3571 then return that. May return INSN itself. */
3574 next_nondeleted_insn (insn)
3577 while (INSN_DELETED_P (insn))
3578 insn = NEXT_INSN (insn);
3582 /* Delete a range of insns from FROM to TO, inclusive.
3583 This is for the sake of peephole optimization, so assume
3584 that whatever these insns do will still be done by a new
3585 peephole insn that will replace them. */
3588 delete_for_peephole (from, to)
3589 register rtx from, to;
3591 register rtx insn = from;
3595 register rtx next = NEXT_INSN (insn);
3596 register rtx prev = PREV_INSN (insn);
3598 if (GET_CODE (insn) != NOTE)
3600 INSN_DELETED_P (insn) = 1;
3602 /* Patch this insn out of the chain. */
3603 /* We don't do this all at once, because we
3604 must preserve all NOTEs. */
3606 NEXT_INSN (prev) = next;
3609 PREV_INSN (next) = prev;
3617 /* Note that if TO is an unconditional jump
3618 we *do not* delete the BARRIER that follows,
3619 since the peephole that replaces this sequence
3620 is also an unconditional jump in that case. */
3623 /* Invert the condition of the jump JUMP, and make it jump
3624 to label NLABEL instead of where it jumps now. */
3627 invert_jump (jump, nlabel)
3630 /* We have to either invert the condition and change the label or
3631 do neither. Either operation could fail. We first try to invert
3632 the jump. If that succeeds, we try changing the label. If that fails,
3633 we invert the jump back to what it was. */
3635 if (! invert_exp (PATTERN (jump), jump))
3638 if (redirect_jump (jump, nlabel))
3641 if (! invert_exp (PATTERN (jump), jump))
3642 /* This should just be putting it back the way it was. */
3648 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3650 Return 1 if we can do so, 0 if we cannot find a way to do so that
3651 matches a pattern. */
3654 invert_exp (x, insn)
3658 register RTX_CODE code;
3662 code = GET_CODE (x);
3664 if (code == IF_THEN_ELSE)
3666 register rtx comp = XEXP (x, 0);
3669 /* We can do this in two ways: The preferable way, which can only
3670 be done if this is not an integer comparison, is to reverse
3671 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3672 of the IF_THEN_ELSE. If we can't do either, fail. */
3674 if (can_reverse_comparison_p (comp, insn)
3675 && validate_change (insn, &XEXP (x, 0),
3676 gen_rtx (reverse_condition (GET_CODE (comp)),
3677 GET_MODE (comp), XEXP (comp, 0),
3678 XEXP (comp, 1)), 0))
3682 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3683 validate_change (insn, &XEXP (x, 2), tem, 1);
3684 return apply_change_group ();
3687 fmt = GET_RTX_FORMAT (code);
3688 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3691 if (! invert_exp (XEXP (x, i), insn))
3696 for (j = 0; j < XVECLEN (x, i); j++)
3697 if (!invert_exp (XVECEXP (x, i, j), insn))
3705 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3706 If the old jump target label is unused as a result,
3707 it and the code following it may be deleted.
3709 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3712 The return value will be 1 if the change was made, 0 if it wasn't (this
3713 can only occur for NLABEL == 0). */
3716 redirect_jump (jump, nlabel)
3719 register rtx olabel = JUMP_LABEL (jump);
3721 if (nlabel == olabel)
3724 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3727 /* If this is an unconditional branch, delete it from the jump_chain of
3728 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3729 have UID's in range and JUMP_CHAIN is valid). */
3730 if (jump_chain && (simplejump_p (jump)
3731 || GET_CODE (PATTERN (jump)) == RETURN))
3733 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3735 delete_from_jump_chain (jump);
3736 if (label_index < max_jump_chain
3737 && INSN_UID (jump) < max_jump_chain)
3739 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3740 jump_chain[label_index] = jump;
3744 JUMP_LABEL (jump) = nlabel;
3746 ++LABEL_NUSES (nlabel);
3748 if (olabel && --LABEL_NUSES (olabel) == 0)
3749 delete_insn (olabel);
3754 /* Delete the instruction JUMP from any jump chain it might be on. */
3757 delete_from_jump_chain (jump)
3761 rtx olabel = JUMP_LABEL (jump);
3763 /* Handle unconditional jumps. */
3764 if (jump_chain && olabel != 0
3765 && INSN_UID (olabel) < max_jump_chain
3766 && simplejump_p (jump))
3767 index = INSN_UID (olabel);
3768 /* Handle return insns. */
3769 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3773 if (jump_chain[index] == jump)
3774 jump_chain[index] = jump_chain[INSN_UID (jump)];
3779 for (insn = jump_chain[index];
3781 insn = jump_chain[INSN_UID (insn)])
3782 if (jump_chain[INSN_UID (insn)] == jump)
3784 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3790 /* If NLABEL is nonzero, throughout the rtx at LOC,
3791 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3792 zero, alter (RETURN) to (LABEL_REF NLABEL).
3794 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3795 validity with validate_change. Convert (set (pc) (label_ref olabel))
3798 Return 0 if we found a change we would like to make but it is invalid.
3799 Otherwise, return 1. */
3802 redirect_exp (loc, olabel, nlabel, insn)
3807 register rtx x = *loc;
3808 register RTX_CODE code = GET_CODE (x);
3812 if (code == LABEL_REF)
3814 if (XEXP (x, 0) == olabel)
3817 XEXP (x, 0) = nlabel;
3819 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3823 else if (code == RETURN && olabel == 0)
3825 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3826 if (loc == &PATTERN (insn))
3827 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3828 return validate_change (insn, loc, x, 0);
3831 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3832 && GET_CODE (SET_SRC (x)) == LABEL_REF
3833 && XEXP (SET_SRC (x), 0) == olabel)
3834 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3836 fmt = GET_RTX_FORMAT (code);
3837 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3840 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3845 for (j = 0; j < XVECLEN (x, i); j++)
3846 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3854 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3856 If the old jump target label (before the dispatch table) becomes unused,
3857 it and the dispatch table may be deleted. In that case, find the insn
3858 before the jump references that label and delete it and logical successors
3862 redirect_tablejump (jump, nlabel)
3865 register rtx olabel = JUMP_LABEL (jump);
3867 /* Add this jump to the jump_chain of NLABEL. */
3868 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3869 && INSN_UID (jump) < max_jump_chain)
3871 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3872 jump_chain[INSN_UID (nlabel)] = jump;
3875 PATTERN (jump) = gen_jump (nlabel);
3876 JUMP_LABEL (jump) = nlabel;
3877 ++LABEL_NUSES (nlabel);
3878 INSN_CODE (jump) = -1;
3880 if (--LABEL_NUSES (olabel) == 0)
3882 delete_labelref_insn (jump, olabel, 0);
3883 delete_insn (olabel);
3887 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3888 If we found one, delete it and then delete this insn if DELETE_THIS is
3889 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3892 delete_labelref_insn (insn, label, delete_this)
3899 if (GET_CODE (insn) != NOTE
3900 && reg_mentioned_p (label, PATTERN (insn)))
3911 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3912 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3926 /* Like rtx_equal_p except that it considers two REGs as equal
3927 if they renumber to the same value and considers two commutative
3928 operations to be the same if the order of the operands has been
3932 rtx_renumbered_equal_p (x, y)
3936 register RTX_CODE code = GET_CODE (x);
3942 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3943 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3944 && GET_CODE (SUBREG_REG (y)) == REG)))
3946 int reg_x = -1, reg_y = -1;
3947 int word_x = 0, word_y = 0;
3949 if (GET_MODE (x) != GET_MODE (y))
3952 /* If we haven't done any renumbering, don't
3953 make any assumptions. */
3954 if (reg_renumber == 0)
3955 return rtx_equal_p (x, y);
3959 reg_x = REGNO (SUBREG_REG (x));
3960 word_x = SUBREG_WORD (x);
3962 if (reg_renumber[reg_x] >= 0)
3964 reg_x = reg_renumber[reg_x] + word_x;
3972 if (reg_renumber[reg_x] >= 0)
3973 reg_x = reg_renumber[reg_x];
3976 if (GET_CODE (y) == SUBREG)
3978 reg_y = REGNO (SUBREG_REG (y));
3979 word_y = SUBREG_WORD (y);
3981 if (reg_renumber[reg_y] >= 0)
3983 reg_y = reg_renumber[reg_y];
3991 if (reg_renumber[reg_y] >= 0)
3992 reg_y = reg_renumber[reg_y];
3995 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3998 /* Now we have disposed of all the cases
3999 in which different rtx codes can match. */
4000 if (code != GET_CODE (y))
4012 return INTVAL (x) == INTVAL (y);
4015 /* We can't assume nonlocal labels have their following insns yet. */
4016 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4017 return XEXP (x, 0) == XEXP (y, 0);
4019 /* Two label-refs are equivalent if they point at labels
4020 in the same position in the instruction stream. */
4021 return (next_real_insn (XEXP (x, 0))
4022 == next_real_insn (XEXP (y, 0)));
4025 return XSTR (x, 0) == XSTR (y, 0);
4028 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4030 if (GET_MODE (x) != GET_MODE (y))
4033 /* For commutative operations, the RTX match if the operand match in any
4034 order. Also handle the simple binary and unary cases without a loop. */
4035 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4036 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4037 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4038 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4039 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4040 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4041 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4042 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4043 else if (GET_RTX_CLASS (code) == '1')
4044 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4046 /* Compare the elements. If any pair of corresponding elements
4047 fail to match, return 0 for the whole things. */
4049 fmt = GET_RTX_FORMAT (code);
4050 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4056 if (XWINT (x, i) != XWINT (y, i))
4061 if (XINT (x, i) != XINT (y, i))
4066 if (strcmp (XSTR (x, i), XSTR (y, i)))
4071 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4076 if (XEXP (x, i) != XEXP (y, i))
4083 if (XVECLEN (x, i) != XVECLEN (y, i))
4085 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4086 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4097 /* If X is a hard register or equivalent to one or a subregister of one,
4098 return the hard register number. If X is a pseudo register that was not
4099 assigned a hard register, return the pseudo register number. Otherwise,
4100 return -1. Any rtx is valid for X. */
4106 if (GET_CODE (x) == REG)
4108 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4109 return reg_renumber[REGNO (x)];
4112 if (GET_CODE (x) == SUBREG)
4114 int base = true_regnum (SUBREG_REG (x));
4115 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4116 return SUBREG_WORD (x) + base;
4121 /* Optimize code of the form:
4123 for (x = a[i]; x; ...)
4125 for (x = a[i]; x; ...)
4129 Loop optimize will change the above code into
4133 { ...; if (! (x = ...)) break; }
4136 { ...; if (! (x = ...)) break; }
4139 In general, if the first test fails, the program can branch
4140 directly to `foo' and skip the second try which is doomed to fail.
4141 We run this after loop optimization and before flow analysis. */
4143 /* When comparing the insn patterns, we track the fact that different
4144 pseudo-register numbers may have been used in each computation.
4145 The following array stores an equivalence -- same_regs[I] == J means
4146 that pseudo register I was used in the first set of tests in a context
4147 where J was used in the second set. We also count the number of such
4148 pending equivalences. If nonzero, the expressions really aren't the
4151 static int *same_regs;
4153 static int num_same_regs;
4155 /* Track any registers modified between the target of the first jump and
4156 the second jump. They never compare equal. */
4158 static char *modified_regs;
4160 /* Record if memory was modified. */
4162 static int modified_mem;
4164 /* Called via note_stores on each insn between the target of the first
4165 branch and the second branch. It marks any changed registers. */
4168 mark_modified_reg (dest, x)
4174 if (GET_CODE (dest) == SUBREG)
4175 dest = SUBREG_REG (dest);
4177 if (GET_CODE (dest) == MEM)
4180 if (GET_CODE (dest) != REG)
4183 regno = REGNO (dest);
4184 if (regno >= FIRST_PSEUDO_REGISTER)
4185 modified_regs[regno] = 1;
4187 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4188 modified_regs[regno + i] = 1;
4191 /* F is the first insn in the chain of insns. */
4194 thread_jumps (f, max_reg, flag_before_loop)
4197 int flag_before_loop;
4199 /* Basic algorithm is to find a conditional branch,
4200 the label it may branch to, and the branch after
4201 that label. If the two branches test the same condition,
4202 walk back from both branch paths until the insn patterns
4203 differ, or code labels are hit. If we make it back to
4204 the target of the first branch, then we know that the first branch
4205 will either always succeed or always fail depending on the relative
4206 senses of the two branches. So adjust the first branch accordingly
4209 rtx label, b1, b2, t1, t2;
4210 enum rtx_code code1, code2;
4211 rtx b1op0, b1op1, b2op0, b2op1;
4216 /* Allocate register tables and quick-reset table. */
4217 modified_regs = (char *) alloca (max_reg * sizeof (char));
4218 same_regs = (int *) alloca (max_reg * sizeof (int));
4219 all_reset = (int *) alloca (max_reg * sizeof (int));
4220 for (i = 0; i < max_reg; i++)
4227 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4229 /* Get to a candidate branch insn. */
4230 if (GET_CODE (b1) != JUMP_INSN
4231 || ! condjump_p (b1) || simplejump_p (b1)
4232 || JUMP_LABEL (b1) == 0)
4235 bzero (modified_regs, max_reg * sizeof (char));
4238 bcopy ((char *) all_reset, (char *) same_regs,
4239 max_reg * sizeof (int));
4242 label = JUMP_LABEL (b1);
4244 /* Look for a branch after the target. Record any registers and
4245 memory modified between the target and the branch. Stop when we
4246 get to a label since we can't know what was changed there. */
4247 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4249 if (GET_CODE (b2) == CODE_LABEL)
4252 else if (GET_CODE (b2) == JUMP_INSN)
4254 /* If this is an unconditional jump and is the only use of
4255 its target label, we can follow it. */
4256 if (simplejump_p (b2)
4257 && JUMP_LABEL (b2) != 0
4258 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4260 b2 = JUMP_LABEL (b2);
4267 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4270 if (GET_CODE (b2) == CALL_INSN)
4273 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4274 if (call_used_regs[i] && ! fixed_regs[i]
4275 && i != STACK_POINTER_REGNUM
4276 && i != FRAME_POINTER_REGNUM
4277 && i != HARD_FRAME_POINTER_REGNUM
4278 && i != ARG_POINTER_REGNUM)
4279 modified_regs[i] = 1;
4282 note_stores (PATTERN (b2), mark_modified_reg);
4285 /* Check the next candidate branch insn from the label
4288 || GET_CODE (b2) != JUMP_INSN
4290 || ! condjump_p (b2)
4291 || simplejump_p (b2))
4294 /* Get the comparison codes and operands, reversing the
4295 codes if appropriate. If we don't have comparison codes,
4296 we can't do anything. */
4297 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4298 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4299 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4300 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4301 code1 = reverse_condition (code1);
4303 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4304 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4305 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4306 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4307 code2 = reverse_condition (code2);
4309 /* If they test the same things and knowing that B1 branches
4310 tells us whether or not B2 branches, check if we
4311 can thread the branch. */
4312 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4313 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4314 && (comparison_dominates_p (code1, code2)
4315 || comparison_dominates_p (code1, reverse_condition (code2))))
4317 t1 = prev_nonnote_insn (b1);
4318 t2 = prev_nonnote_insn (b2);
4320 while (t1 != 0 && t2 != 0)
4324 /* We have reached the target of the first branch.
4325 If there are no pending register equivalents,
4326 we know that this branch will either always
4327 succeed (if the senses of the two branches are
4328 the same) or always fail (if not). */
4331 if (num_same_regs != 0)
4334 if (comparison_dominates_p (code1, code2))
4335 new_label = JUMP_LABEL (b2);
4337 new_label = get_label_after (b2);
4339 if (JUMP_LABEL (b1) != new_label)
4341 rtx prev = PREV_INSN (new_label);
4343 if (flag_before_loop
4344 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4346 /* Don't thread to the loop label. If a loop
4347 label is reused, loop optimization will
4348 be disabled for that loop. */
4349 new_label = gen_label_rtx ();
4350 emit_label_after (new_label, PREV_INSN (prev));
4352 changed |= redirect_jump (b1, new_label);
4357 /* If either of these is not a normal insn (it might be
4358 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4359 have already been skipped above.) Similarly, fail
4360 if the insns are different. */
4361 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4362 || recog_memoized (t1) != recog_memoized (t2)
4363 || ! rtx_equal_for_thread_p (PATTERN (t1),
4367 t1 = prev_nonnote_insn (t1);
4368 t2 = prev_nonnote_insn (t2);
4375 /* This is like RTX_EQUAL_P except that it knows about our handling of
4376 possibly equivalent registers and knows to consider volatile and
4377 modified objects as not equal.
4379 YINSN is the insn containing Y. */
4382 rtx_equal_for_thread_p (x, y, yinsn)
4388 register enum rtx_code code;
4391 code = GET_CODE (x);
4392 /* Rtx's of different codes cannot be equal. */
4393 if (code != GET_CODE (y))
4396 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4397 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4399 if (GET_MODE (x) != GET_MODE (y))
4402 /* For commutative operations, the RTX match if the operand match in any
4403 order. Also handle the simple binary and unary cases without a loop. */
4404 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4405 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4406 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4407 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4408 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4409 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4410 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4411 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4412 else if (GET_RTX_CLASS (code) == '1')
4413 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4415 /* Handle special-cases first. */
4419 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4422 /* If neither is user variable or hard register, check for possible
4424 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4425 || REGNO (x) < FIRST_PSEUDO_REGISTER
4426 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4429 if (same_regs[REGNO (x)] == -1)
4431 same_regs[REGNO (x)] = REGNO (y);
4434 /* If this is the first time we are seeing a register on the `Y'
4435 side, see if it is the last use. If not, we can't thread the
4436 jump, so mark it as not equivalent. */
4437 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
4443 return (same_regs[REGNO (x)] == REGNO (y));
4448 /* If memory modified or either volatile, not equivalent.
4449 Else, check address. */
4450 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4453 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4456 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4462 /* Cancel a pending `same_regs' if setting equivalenced registers.
4463 Then process source. */
4464 if (GET_CODE (SET_DEST (x)) == REG
4465 && GET_CODE (SET_DEST (y)) == REG)
4467 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4469 same_regs[REGNO (SET_DEST (x))] = -1;
4472 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4476 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4479 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4482 return XEXP (x, 0) == XEXP (y, 0);
4485 return XSTR (x, 0) == XSTR (y, 0);
4491 fmt = GET_RTX_FORMAT (code);
4492 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4497 if (XWINT (x, i) != XWINT (y, i))
4503 if (XINT (x, i) != XINT (y, i))
4509 /* Two vectors must have the same length. */
4510 if (XVECLEN (x, i) != XVECLEN (y, i))
4513 /* And the corresponding elements must match. */
4514 for (j = 0; j < XVECLEN (x, i); j++)
4515 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4516 XVECEXP (y, i, j), yinsn) == 0)
4521 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4527 if (strcmp (XSTR (x, i), XSTR (y, i)))
4532 /* These are just backpointers, so they don't matter. */
4538 /* It is believed that rtx's at this level will never
4539 contain anything but integers and other rtx's,
4540 except for within LABEL_REFs and SYMBOL_REFs. */