1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-95, 1996 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
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);
866 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
867 to x = a; if (...) goto l; x = b;
868 if A is sufficiently simple, the test doesn't involve X,
869 and nothing in the test modifies A or X.
871 If we have small register classes, we also can't do this if X
874 If the "x = a;" insn has any REG_NOTES, we don't do this because
875 of the possibility that we are running after CSE and there is a
876 REG_EQUAL note that is only valid if the branch has already been
877 taken. If we move the insn with the REG_EQUAL note, we may
878 fold the comparison to always be false in a later CSE pass.
879 (We could also delete the REG_NOTES when moving the insn, but it
880 seems simpler to not move it.) An exception is that we can move
881 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
882 value is the same as "a".
888 TEMP to the jump insn preceding "x = a;"
890 TEMP2 to the insn that sets "x = b;"
891 TEMP3 to the insn that sets "x = a;"
892 TEMP4 to the set of "x = a"; */
894 if (this_is_simplejump
895 && (temp2 = next_active_insn (insn)) != 0
896 && GET_CODE (temp2) == INSN
897 && (temp4 = single_set (temp2)) != 0
898 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
899 #ifdef SMALL_REGISTER_CLASSES
900 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
903 && (temp3 = prev_active_insn (insn)) != 0
904 && GET_CODE (temp3) == INSN
905 && (temp4 = single_set (temp3)) != 0
906 && rtx_equal_p (SET_DEST (temp4), temp1)
907 && (GET_CODE (SET_SRC (temp4)) == REG
908 || GET_CODE (SET_SRC (temp4)) == SUBREG
909 || CONSTANT_P (SET_SRC (temp4)))
910 && (REG_NOTES (temp3) == 0
911 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
912 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
913 && XEXP (REG_NOTES (temp3), 1) == 0
914 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
916 && (temp = prev_active_insn (temp3)) != 0
917 && condjump_p (temp) && ! simplejump_p (temp)
918 /* TEMP must skip over the "x = a;" insn */
919 && prev_real_insn (JUMP_LABEL (temp)) == insn
920 && no_labels_between_p (temp, insn))
922 rtx prev_label = JUMP_LABEL (temp);
923 rtx insert_after = prev_nonnote_insn (temp);
926 /* We cannot insert anything between a set of cc and its use. */
927 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
928 && sets_cc0_p (PATTERN (insert_after)))
929 insert_after = prev_nonnote_insn (insert_after);
931 ++LABEL_NUSES (prev_label);
934 && no_labels_between_p (insert_after, temp)
935 && ! reg_referenced_between_p (temp1, insert_after, temp)
936 && ! reg_set_between_p (temp1, insert_after, temp)
937 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
938 || ! reg_set_between_p (SET_SRC (temp4),
940 && invert_jump (temp, JUMP_LABEL (insn)))
942 emit_insn_after_with_line_notes (PATTERN (temp3),
943 insert_after, temp3);
946 /* Set NEXT to an insn that we know won't go away. */
950 if (prev_label && --LABEL_NUSES (prev_label) == 0)
951 delete_insn (prev_label);
957 /* If we have if (...) x = exp; and branches are expensive,
958 EXP is a single insn, does not have any side effects, cannot
959 trap, and is not too costly, convert this to
960 t = exp; if (...) x = t;
962 Don't do this when we have CC0 because it is unlikely to help
963 and we'd need to worry about where to place the new insn and
964 the potential for conflicts. We also can't do this when we have
965 notes on the insn for the same reason as above.
969 TEMP to the "x = exp;" insn.
970 TEMP1 to the single set in the "x = exp; insn.
973 if (! reload_completed
974 && this_is_condjump && ! this_is_simplejump
976 && (temp = next_nonnote_insn (insn)) != 0
977 && GET_CODE (temp) == INSN
978 && REG_NOTES (temp) == 0
979 && (reallabelprev == temp
980 || ((temp2 = next_active_insn (temp)) != 0
981 && simplejump_p (temp2)
982 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
983 && (temp1 = single_set (temp)) != 0
984 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
985 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
986 #ifdef SMALL_REGISTER_CLASSES
987 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
989 && GET_CODE (SET_SRC (temp1)) != REG
990 && GET_CODE (SET_SRC (temp1)) != SUBREG
991 && GET_CODE (SET_SRC (temp1)) != CONST_INT
992 && ! side_effects_p (SET_SRC (temp1))
993 && ! may_trap_p (SET_SRC (temp1))
994 && rtx_cost (SET_SRC (temp1), SET) < 10)
996 rtx new = gen_reg_rtx (GET_MODE (temp2));
998 if (validate_change (temp, &SET_DEST (temp1), new, 0))
1000 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1001 emit_insn_after_with_line_notes (PATTERN (temp),
1002 PREV_INSN (insn), temp);
1004 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1008 /* Similarly, if it takes two insns to compute EXP but they
1009 have the same destination. Here TEMP3 will be the second
1010 insn and TEMP4 the SET from that insn. */
1012 if (! reload_completed
1013 && this_is_condjump && ! this_is_simplejump
1015 && (temp = next_nonnote_insn (insn)) != 0
1016 && GET_CODE (temp) == INSN
1017 && REG_NOTES (temp) == 0
1018 && (temp3 = next_nonnote_insn (temp)) != 0
1019 && GET_CODE (temp3) == INSN
1020 && REG_NOTES (temp3) == 0
1021 && (reallabelprev == temp3
1022 || ((temp2 = next_active_insn (temp3)) != 0
1023 && simplejump_p (temp2)
1024 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1025 && (temp1 = single_set (temp)) != 0
1026 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
1027 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1028 #ifdef SMALL_REGISTER_CLASSES
1029 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
1031 && ! side_effects_p (SET_SRC (temp1))
1032 && ! may_trap_p (SET_SRC (temp1))
1033 && rtx_cost (SET_SRC (temp1), SET) < 10
1034 && (temp4 = single_set (temp3)) != 0
1035 && rtx_equal_p (SET_DEST (temp4), temp2)
1036 && ! side_effects_p (SET_SRC (temp4))
1037 && ! may_trap_p (SET_SRC (temp4))
1038 && rtx_cost (SET_SRC (temp4), SET) < 10)
1040 rtx new = gen_reg_rtx (GET_MODE (temp2));
1042 if (validate_change (temp, &SET_DEST (temp1), new, 0))
1044 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1045 emit_insn_after_with_line_notes (PATTERN (temp),
1046 PREV_INSN (insn), temp);
1047 emit_insn_after_with_line_notes
1048 (replace_rtx (PATTERN (temp3), temp2, new),
1049 PREV_INSN (insn), temp3);
1051 delete_insn (temp3);
1052 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1056 /* Finally, handle the case where two insns are used to
1057 compute EXP but a temporary register is used. Here we must
1058 ensure that the temporary register is not used anywhere else. */
1060 if (! reload_completed
1062 && this_is_condjump && ! this_is_simplejump
1064 && (temp = next_nonnote_insn (insn)) != 0
1065 && GET_CODE (temp) == INSN
1066 && REG_NOTES (temp) == 0
1067 && (temp3 = next_nonnote_insn (temp)) != 0
1068 && GET_CODE (temp3) == INSN
1069 && REG_NOTES (temp3) == 0
1070 && (reallabelprev == temp3
1071 || ((temp2 = next_active_insn (temp3)) != 0
1072 && simplejump_p (temp2)
1073 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1074 && (temp1 = single_set (temp)) != 0
1075 && (temp5 = SET_DEST (temp1),
1076 (GET_CODE (temp5) == REG
1077 || (GET_CODE (temp5) == SUBREG
1078 && (temp5 = SUBREG_REG (temp5),
1079 GET_CODE (temp5) == REG))))
1080 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
1081 && regno_first_uid[REGNO (temp5)] == INSN_UID (temp)
1082 && regno_last_uid[REGNO (temp5)] == INSN_UID (temp3)
1083 && ! side_effects_p (SET_SRC (temp1))
1084 && ! may_trap_p (SET_SRC (temp1))
1085 && rtx_cost (SET_SRC (temp1), SET) < 10
1086 && (temp4 = single_set (temp3)) != 0
1087 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
1088 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1089 #ifdef SMALL_REGISTER_CLASSES
1090 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
1092 && rtx_equal_p (SET_DEST (temp4), temp2)
1093 && ! side_effects_p (SET_SRC (temp4))
1094 && ! may_trap_p (SET_SRC (temp4))
1095 && rtx_cost (SET_SRC (temp4), SET) < 10)
1097 rtx new = gen_reg_rtx (GET_MODE (temp2));
1099 if (validate_change (temp3, &SET_DEST (temp4), new, 0))
1101 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1102 emit_insn_after_with_line_notes (PATTERN (temp),
1103 PREV_INSN (insn), temp);
1104 emit_insn_after_with_line_notes (PATTERN (temp3),
1105 PREV_INSN (insn), temp3);
1107 delete_insn (temp3);
1108 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1111 #endif /* HAVE_cc0 */
1113 /* Try to use a conditional move (if the target has them), or a
1114 store-flag insn. The general case is:
1116 1) x = a; if (...) x = b; and
1119 If the jump would be faster, the machine should not have defined
1120 the movcc or scc insns!. These cases are often made by the
1121 previous optimization.
1123 The second case is treated as x = x; if (...) x = b;.
1125 INSN here is the jump around the store. We set:
1127 TEMP to the "x = b;" insn.
1130 TEMP3 to A (X in the second case).
1131 TEMP4 to the condition being tested.
1132 TEMP5 to the earliest insn used to find the condition. */
1134 if (/* We can't do this after reload has completed. */
1136 && this_is_condjump && ! this_is_simplejump
1137 /* Set TEMP to the "x = b;" insn. */
1138 && (temp = next_nonnote_insn (insn)) != 0
1139 && GET_CODE (temp) == INSN
1140 && GET_CODE (PATTERN (temp)) == SET
1141 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1142 #ifdef SMALL_REGISTER_CLASSES
1143 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
1145 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1146 || GET_CODE (temp2) == SUBREG
1147 /* ??? How about floating point constants? */
1148 || GET_CODE (temp2) == CONST_INT)
1149 /* Allow either form, but prefer the former if both apply.
1150 There is no point in using the old value of TEMP1 if
1151 it is a register, since cse will alias them. It can
1152 lose if the old value were a hard register since CSE
1153 won't replace hard registers. */
1154 && (((temp3 = reg_set_last (temp1, insn)) != 0)
1155 /* Make the latter case look like x = x; if (...) x = b; */
1156 || (temp3 = temp1, 1))
1157 /* INSN must either branch to the insn after TEMP or the insn
1158 after TEMP must branch to the same place as INSN. */
1159 && (reallabelprev == temp
1160 || ((temp4 = next_active_insn (temp)) != 0
1161 && simplejump_p (temp4)
1162 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1163 && (temp4 = get_condition (insn, &temp5)) != 0
1164 /* We must be comparing objects whose modes imply the size.
1165 We could handle BLKmode if (1) emit_store_flag could
1166 and (2) we could find the size reliably. */
1167 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1168 /* Even if branches are cheap, the store_flag optimization
1169 can win when the operation to be performed can be
1170 expressed directly. */
1172 /* If the previous insn sets CC0 and something else, we can't
1173 do this since we are going to delete that insn. */
1175 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1176 && GET_CODE (temp6) == INSN
1177 && (sets_cc0_p (PATTERN (temp6)) == -1
1178 || (sets_cc0_p (PATTERN (temp6)) == 1
1179 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1183 #ifdef HAVE_conditional_move
1184 /* First try a conditional move. */
1186 enum rtx_code code = GET_CODE (temp4);
1188 rtx cond0, cond1, aval, bval;
1191 /* Copy the compared variables into cond0 and cond1, so that
1192 any side effects performed in or after the old comparison,
1193 will not affect our compare which will come later. */
1194 /* ??? Is it possible to just use the comparison in the jump
1195 insn? After all, we're going to delete it. We'd have
1196 to modify emit_conditional_move to take a comparison rtx
1197 instead or write a new function. */
1198 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1199 /* We want the target to be able to simplify comparisons with
1200 zero (and maybe other constants as well), so don't create
1201 pseudos for them. There's no need to either. */
1202 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1203 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1204 cond1 = XEXP (temp4, 1);
1206 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1212 target = emit_conditional_move (var, code,
1213 cond0, cond1, VOIDmode,
1214 aval, bval, GET_MODE (var),
1215 (code == LTU || code == GEU
1216 || code == LEU || code == GTU));
1222 /* Save the conditional move sequence but don't emit it
1223 yet. On some machines, like the alpha, it is possible
1224 that temp5 == insn, so next generate the sequence that
1225 saves the compared values and then emit both
1226 sequences ensuring seq1 occurs before seq2. */
1227 seq2 = get_insns ();
1230 /* Now that we can't fail, generate the copy insns that
1231 preserve the compared values. */
1233 emit_move_insn (cond0, XEXP (temp4, 0));
1234 if (cond1 != XEXP (temp4, 1))
1235 emit_move_insn (cond1, XEXP (temp4, 1));
1236 seq1 = get_insns ();
1239 emit_insns_before (seq1, temp5);
1240 /* Insert conditional move after insn, to be sure that
1241 the jump and a possible compare won't be separated */
1242 emit_insns_after (seq2, insn);
1244 /* ??? We can also delete the insn that sets X to A.
1245 Flow will do it too though. */
1247 next = NEXT_INSN (insn);
1257 /* That didn't work, try a store-flag insn.
1259 We further divide the cases into:
1261 1) x = a; if (...) x = b; and either A or B is zero,
1262 2) if (...) x = 0; and jumps are expensive,
1263 3) x = a; if (...) x = b; and A and B are constants where all
1264 the set bits in A are also set in B and jumps are expensive,
1265 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1267 5) if (...) x = b; if jumps are even more expensive. */
1269 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1270 && ((GET_CODE (temp3) == CONST_INT)
1271 /* Make the latter case look like
1272 x = x; if (...) x = 0; */
1275 && temp2 == const0_rtx)
1276 || BRANCH_COST >= 3)))
1277 /* If B is zero, OK; if A is zero, can only do (1) if we
1278 can reverse the condition. See if (3) applies possibly
1279 by reversing the condition. Prefer reversing to (4) when
1280 branches are very expensive. */
1281 && (((BRANCH_COST >= 2
1282 || STORE_FLAG_VALUE == -1
1283 || (STORE_FLAG_VALUE == 1
1284 /* Check that the mask is a power of two,
1285 so that it can probably be generated
1287 && exact_log2 (INTVAL (temp3)) >= 0))
1288 && (reversep = 0, temp2 == const0_rtx))
1289 || ((BRANCH_COST >= 2
1290 || STORE_FLAG_VALUE == -1
1291 || (STORE_FLAG_VALUE == 1
1292 && exact_log2 (INTVAL (temp2)) >= 0))
1293 && temp3 == const0_rtx
1294 && (reversep = can_reverse_comparison_p (temp4, insn)))
1295 || (BRANCH_COST >= 2
1296 && GET_CODE (temp2) == CONST_INT
1297 && GET_CODE (temp3) == CONST_INT
1298 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1299 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1300 && (reversep = can_reverse_comparison_p (temp4,
1302 || BRANCH_COST >= 3)
1305 enum rtx_code code = GET_CODE (temp4);
1306 rtx uval, cval, var = temp1;
1310 /* If necessary, reverse the condition. */
1312 code = reverse_condition (code), uval = temp2, cval = temp3;
1314 uval = temp3, cval = temp2;
1316 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1317 is the constant 1, it is best to just compute the result
1318 directly. If UVAL is constant and STORE_FLAG_VALUE
1319 includes all of its bits, it is best to compute the flag
1320 value unnormalized and `and' it with UVAL. Otherwise,
1321 normalize to -1 and `and' with UVAL. */
1322 normalizep = (cval != const0_rtx ? -1
1323 : (uval == const1_rtx ? 1
1324 : (GET_CODE (uval) == CONST_INT
1325 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1328 /* We will be putting the store-flag insn immediately in
1329 front of the comparison that was originally being done,
1330 so we know all the variables in TEMP4 will be valid.
1331 However, this might be in front of the assignment of
1332 A to VAR. If it is, it would clobber the store-flag
1333 we will be emitting.
1335 Therefore, emit into a temporary which will be copied to
1336 VAR immediately after TEMP. */
1339 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1340 XEXP (temp4, 0), XEXP (temp4, 1),
1342 (code == LTU || code == LEU
1343 || code == GEU || code == GTU),
1353 /* Put the store-flag insns in front of the first insn
1354 used to compute the condition to ensure that we
1355 use the same values of them as the current
1356 comparison. However, the remainder of the insns we
1357 generate will be placed directly in front of the
1358 jump insn, in case any of the pseudos we use
1359 are modified earlier. */
1361 emit_insns_before (seq, temp5);
1365 /* Both CVAL and UVAL are non-zero. */
1366 if (cval != const0_rtx && uval != const0_rtx)
1370 tem1 = expand_and (uval, target, NULL_RTX);
1371 if (GET_CODE (cval) == CONST_INT
1372 && GET_CODE (uval) == CONST_INT
1373 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1377 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1378 target, NULL_RTX, 0);
1379 tem2 = expand_and (cval, tem2,
1380 (GET_CODE (tem2) == REG
1384 /* If we usually make new pseudos, do so here. This
1385 turns out to help machines that have conditional
1387 /* ??? Conditional moves have already been handled.
1388 This may be obsolete. */
1390 if (flag_expensive_optimizations)
1393 target = expand_binop (GET_MODE (var), ior_optab,
1397 else if (normalizep != 1)
1399 /* We know that either CVAL or UVAL is zero. If
1400 UVAL is zero, negate TARGET and `and' with CVAL.
1401 Otherwise, `and' with UVAL. */
1402 if (uval == const0_rtx)
1404 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1405 target, NULL_RTX, 0);
1409 target = expand_and (uval, target,
1410 (GET_CODE (target) == REG
1411 && ! preserve_subexpressions_p ()
1412 ? target : NULL_RTX));
1415 emit_move_insn (var, target);
1419 /* If INSN uses CC0, we must not separate it from the
1420 insn that sets cc0. */
1421 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1422 before = prev_nonnote_insn (before);
1424 emit_insns_before (seq, before);
1427 next = NEXT_INSN (insn);
1437 /* If branches are expensive, convert
1438 if (foo) bar++; to bar += (foo != 0);
1439 and similarly for "bar--;"
1441 INSN is the conditional branch around the arithmetic. We set:
1443 TEMP is the arithmetic insn.
1444 TEMP1 is the SET doing the arithmetic.
1445 TEMP2 is the operand being incremented or decremented.
1446 TEMP3 to the condition being tested.
1447 TEMP4 to the earliest insn used to find the condition. */
1449 if ((BRANCH_COST >= 2
1457 && ! reload_completed
1458 && this_is_condjump && ! this_is_simplejump
1459 && (temp = next_nonnote_insn (insn)) != 0
1460 && (temp1 = single_set (temp)) != 0
1461 && (temp2 = SET_DEST (temp1),
1462 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1463 && GET_CODE (SET_SRC (temp1)) == PLUS
1464 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1465 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1466 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1467 && ! side_effects_p (temp2)
1468 && ! may_trap_p (temp2)
1469 /* INSN must either branch to the insn after TEMP or the insn
1470 after TEMP must branch to the same place as INSN. */
1471 && (reallabelprev == temp
1472 || ((temp3 = next_active_insn (temp)) != 0
1473 && simplejump_p (temp3)
1474 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1475 && (temp3 = get_condition (insn, &temp4)) != 0
1476 /* We must be comparing objects whose modes imply the size.
1477 We could handle BLKmode if (1) emit_store_flag could
1478 and (2) we could find the size reliably. */
1479 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1480 && can_reverse_comparison_p (temp3, insn))
1482 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1483 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1487 /* It must be the case that TEMP2 is not modified in the range
1488 [TEMP4, INSN). The one exception we make is if the insn
1489 before INSN sets TEMP2 to something which is also unchanged
1490 in that range. In that case, we can move the initialization
1491 into our sequence. */
1493 if ((temp5 = prev_active_insn (insn)) != 0
1494 && GET_CODE (temp5) == INSN
1495 && (temp6 = single_set (temp5)) != 0
1496 && rtx_equal_p (temp2, SET_DEST (temp6))
1497 && (CONSTANT_P (SET_SRC (temp6))
1498 || GET_CODE (SET_SRC (temp6)) == REG
1499 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1501 emit_insn (PATTERN (temp5));
1503 init = SET_SRC (temp6);
1506 if (CONSTANT_P (init)
1507 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1508 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1509 XEXP (temp3, 0), XEXP (temp3, 1),
1511 (code == LTU || code == LEU
1512 || code == GTU || code == GEU), 1);
1514 /* If we can do the store-flag, do the addition or
1518 target = expand_binop (GET_MODE (temp2),
1519 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1520 ? add_optab : sub_optab),
1521 temp2, target, temp2, 0, OPTAB_WIDEN);
1525 /* Put the result back in temp2 in case it isn't already.
1526 Then replace the jump, possible a CC0-setting insn in
1527 front of the jump, and TEMP, with the sequence we have
1530 if (target != temp2)
1531 emit_move_insn (temp2, target);
1536 emit_insns_before (seq, temp4);
1540 delete_insn (init_insn);
1542 next = NEXT_INSN (insn);
1544 delete_insn (prev_nonnote_insn (insn));
1554 /* Simplify if (...) x = 1; else {...} if (x) ...
1555 We recognize this case scanning backwards as well.
1557 TEMP is the assignment to x;
1558 TEMP1 is the label at the head of the second if. */
1559 /* ?? This should call get_condition to find the values being
1560 compared, instead of looking for a COMPARE insn when HAVE_cc0
1561 is not defined. This would allow it to work on the m88k. */
1562 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1563 is not defined and the condition is tested by a separate compare
1564 insn. This is because the code below assumes that the result
1565 of the compare dies in the following branch.
1567 Not only that, but there might be other insns between the
1568 compare and branch whose results are live. Those insns need
1571 A way to fix this is to move the insns at JUMP_LABEL (insn)
1572 to before INSN. If we are running before flow, they will
1573 be deleted if they aren't needed. But this doesn't work
1576 This is really a special-case of jump threading, anyway. The
1577 right thing to do is to replace this and jump threading with
1578 much simpler code in cse.
1580 This code has been turned off in the non-cc0 case in the
1584 else if (this_is_simplejump
1585 /* Safe to skip USE and CLOBBER insns here
1586 since they will not be deleted. */
1587 && (temp = prev_active_insn (insn))
1588 && no_labels_between_p (temp, insn)
1589 && GET_CODE (temp) == INSN
1590 && GET_CODE (PATTERN (temp)) == SET
1591 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1592 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1593 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1594 /* If we find that the next value tested is `x'
1595 (TEMP1 is the insn where this happens), win. */
1596 && GET_CODE (temp1) == INSN
1597 && GET_CODE (PATTERN (temp1)) == SET
1599 /* Does temp1 `tst' the value of x? */
1600 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1601 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1602 && (temp1 = next_nonnote_insn (temp1))
1604 /* Does temp1 compare the value of x against zero? */
1605 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1606 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1607 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1608 == SET_DEST (PATTERN (temp)))
1609 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1610 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1612 && condjump_p (temp1))
1614 /* Get the if_then_else from the condjump. */
1615 rtx choice = SET_SRC (PATTERN (temp1));
1616 if (GET_CODE (choice) == IF_THEN_ELSE)
1618 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1619 rtx val = SET_SRC (PATTERN (temp));
1621 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1625 if (cond == const_true_rtx)
1626 ultimate = XEXP (choice, 1);
1627 else if (cond == const0_rtx)
1628 ultimate = XEXP (choice, 2);
1632 if (ultimate == pc_rtx)
1633 ultimate = get_label_after (temp1);
1634 else if (ultimate && GET_CODE (ultimate) != RETURN)
1635 ultimate = XEXP (ultimate, 0);
1637 if (ultimate && JUMP_LABEL(insn) != ultimate)
1638 changed |= redirect_jump (insn, ultimate);
1644 /* @@ This needs a bit of work before it will be right.
1646 Any type of comparison can be accepted for the first and
1647 second compare. When rewriting the first jump, we must
1648 compute the what conditions can reach label3, and use the
1649 appropriate code. We can not simply reverse/swap the code
1650 of the first jump. In some cases, the second jump must be
1654 < == converts to > ==
1655 < != converts to == >
1658 If the code is written to only accept an '==' test for the second
1659 compare, then all that needs to be done is to swap the condition
1660 of the first branch.
1662 It is questionable whether we want this optimization anyways,
1663 since if the user wrote code like this because he/she knew that
1664 the jump to label1 is taken most of the time, then rewriting
1665 this gives slower code. */
1666 /* @@ This should call get_condition to find the values being
1667 compared, instead of looking for a COMPARE insn when HAVE_cc0
1668 is not defined. This would allow it to work on the m88k. */
1669 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1670 is not defined and the condition is tested by a separate compare
1671 insn. This is because the code below assumes that the result
1672 of the compare dies in the following branch. */
1674 /* Simplify test a ~= b
1688 where ~= is an inequality, e.g. >, and ~~= is the swapped
1691 We recognize this case scanning backwards.
1693 TEMP is the conditional jump to `label2';
1694 TEMP1 is the test for `a == b';
1695 TEMP2 is the conditional jump to `label1';
1696 TEMP3 is the test for `a ~= b'. */
1697 else if (this_is_simplejump
1698 && (temp = prev_active_insn (insn))
1699 && no_labels_between_p (temp, insn)
1700 && condjump_p (temp)
1701 && (temp1 = prev_active_insn (temp))
1702 && no_labels_between_p (temp1, temp)
1703 && GET_CODE (temp1) == INSN
1704 && GET_CODE (PATTERN (temp1)) == SET
1706 && sets_cc0_p (PATTERN (temp1)) == 1
1708 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1709 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1710 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1712 && (temp2 = prev_active_insn (temp1))
1713 && no_labels_between_p (temp2, temp1)
1714 && condjump_p (temp2)
1715 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1716 && (temp3 = prev_active_insn (temp2))
1717 && no_labels_between_p (temp3, temp2)
1718 && GET_CODE (PATTERN (temp3)) == SET
1719 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1720 SET_DEST (PATTERN (temp1)))
1721 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1722 SET_SRC (PATTERN (temp3)))
1723 && ! inequality_comparisons_p (PATTERN (temp))
1724 && inequality_comparisons_p (PATTERN (temp2)))
1726 rtx fallthrough_label = JUMP_LABEL (temp2);
1728 ++LABEL_NUSES (fallthrough_label);
1729 if (swap_jump (temp2, JUMP_LABEL (insn)))
1735 if (--LABEL_NUSES (fallthrough_label) == 0)
1736 delete_insn (fallthrough_label);
1739 /* Simplify if (...) {... x = 1;} if (x) ...
1741 We recognize this case backwards.
1743 TEMP is the test of `x';
1744 TEMP1 is the assignment to `x' at the end of the
1745 previous statement. */
1746 /* @@ This should call get_condition to find the values being
1747 compared, instead of looking for a COMPARE insn when HAVE_cc0
1748 is not defined. This would allow it to work on the m88k. */
1749 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1750 is not defined and the condition is tested by a separate compare
1751 insn. This is because the code below assumes that the result
1752 of the compare dies in the following branch. */
1754 /* ??? This has to be turned off. The problem is that the
1755 unconditional jump might indirectly end up branching to the
1756 label between TEMP1 and TEMP. We can't detect this, in general,
1757 since it may become a jump to there after further optimizations.
1758 If that jump is done, it will be deleted, so we will retry
1759 this optimization in the next pass, thus an infinite loop.
1761 The present code prevents this by putting the jump after the
1762 label, but this is not logically correct. */
1764 else if (this_is_condjump
1765 /* Safe to skip USE and CLOBBER insns here
1766 since they will not be deleted. */
1767 && (temp = prev_active_insn (insn))
1768 && no_labels_between_p (temp, insn)
1769 && GET_CODE (temp) == INSN
1770 && GET_CODE (PATTERN (temp)) == SET
1772 && sets_cc0_p (PATTERN (temp)) == 1
1773 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1775 /* Temp must be a compare insn, we can not accept a register
1776 to register move here, since it may not be simply a
1778 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1779 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1780 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1781 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1782 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1784 /* May skip USE or CLOBBER insns here
1785 for checking for opportunity, since we
1786 take care of them later. */
1787 && (temp1 = prev_active_insn (temp))
1788 && GET_CODE (temp1) == INSN
1789 && GET_CODE (PATTERN (temp1)) == SET
1791 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1793 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1794 == SET_DEST (PATTERN (temp1)))
1796 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1797 /* If this isn't true, cse will do the job. */
1798 && ! no_labels_between_p (temp1, temp))
1800 /* Get the if_then_else from the condjump. */
1801 rtx choice = SET_SRC (PATTERN (insn));
1802 if (GET_CODE (choice) == IF_THEN_ELSE
1803 && (GET_CODE (XEXP (choice, 0)) == EQ
1804 || GET_CODE (XEXP (choice, 0)) == NE))
1806 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1811 /* Get the place that condjump will jump to
1812 if it is reached from here. */
1813 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1815 ultimate = XEXP (choice, 1);
1817 ultimate = XEXP (choice, 2);
1818 /* Get it as a CODE_LABEL. */
1819 if (ultimate == pc_rtx)
1820 ultimate = get_label_after (insn);
1822 /* Get the label out of the LABEL_REF. */
1823 ultimate = XEXP (ultimate, 0);
1825 /* Insert the jump immediately before TEMP, specifically
1826 after the label that is between TEMP1 and TEMP. */
1827 last_insn = PREV_INSN (temp);
1829 /* If we would be branching to the next insn, the jump
1830 would immediately be deleted and the re-inserted in
1831 a subsequent pass over the code. So don't do anything
1833 if (next_active_insn (last_insn)
1834 != next_active_insn (ultimate))
1836 emit_barrier_after (last_insn);
1837 p = emit_jump_insn_after (gen_jump (ultimate),
1839 JUMP_LABEL (p) = ultimate;
1840 ++LABEL_NUSES (ultimate);
1841 if (INSN_UID (ultimate) < max_jump_chain
1842 && INSN_CODE (p) < max_jump_chain)
1844 jump_chain[INSN_UID (p)]
1845 = jump_chain[INSN_UID (ultimate)];
1846 jump_chain[INSN_UID (ultimate)] = p;
1854 /* Detect a conditional jump going to the same place
1855 as an immediately following unconditional jump. */
1856 else if (this_is_condjump
1857 && (temp = next_active_insn (insn)) != 0
1858 && simplejump_p (temp)
1859 && (next_active_insn (JUMP_LABEL (insn))
1860 == next_active_insn (JUMP_LABEL (temp))))
1866 /* Detect a conditional jump jumping over an unconditional jump. */
1868 else if ((this_is_condjump || this_is_condjump_in_parallel)
1869 && ! this_is_simplejump
1870 && reallabelprev != 0
1871 && GET_CODE (reallabelprev) == JUMP_INSN
1872 && prev_active_insn (reallabelprev) == insn
1873 && no_labels_between_p (insn, reallabelprev)
1874 && simplejump_p (reallabelprev))
1876 /* When we invert the unconditional jump, we will be
1877 decrementing the usage count of its old label.
1878 Make sure that we don't delete it now because that
1879 might cause the following code to be deleted. */
1880 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1881 rtx prev_label = JUMP_LABEL (insn);
1884 ++LABEL_NUSES (prev_label);
1886 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1888 /* It is very likely that if there are USE insns before
1889 this jump, they hold REG_DEAD notes. These REG_DEAD
1890 notes are no longer valid due to this optimization,
1891 and will cause the life-analysis that following passes
1892 (notably delayed-branch scheduling) to think that
1893 these registers are dead when they are not.
1895 To prevent this trouble, we just remove the USE insns
1896 from the insn chain. */
1898 while (prev_uses && GET_CODE (prev_uses) == INSN
1899 && GET_CODE (PATTERN (prev_uses)) == USE)
1901 rtx useless = prev_uses;
1902 prev_uses = prev_nonnote_insn (prev_uses);
1903 delete_insn (useless);
1906 delete_insn (reallabelprev);
1911 /* We can now safely delete the label if it is unreferenced
1912 since the delete_insn above has deleted the BARRIER. */
1913 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1914 delete_insn (prev_label);
1919 /* Detect a jump to a jump. */
1921 nlabel = follow_jumps (JUMP_LABEL (insn));
1922 if (nlabel != JUMP_LABEL (insn)
1923 && redirect_jump (insn, nlabel))
1929 /* Look for if (foo) bar; else break; */
1930 /* The insns look like this:
1931 insn = condjump label1;
1932 ...range1 (some insns)...
1935 ...range2 (some insns)...
1936 jump somewhere unconditionally
1939 rtx label1 = next_label (insn);
1940 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1941 /* Don't do this optimization on the first round, so that
1942 jump-around-a-jump gets simplified before we ask here
1943 whether a jump is unconditional.
1945 Also don't do it when we are called after reload since
1946 it will confuse reorg. */
1948 && (reload_completed ? ! flag_delayed_branch : 1)
1949 /* Make sure INSN is something we can invert. */
1950 && condjump_p (insn)
1952 && JUMP_LABEL (insn) == label1
1953 && LABEL_NUSES (label1) == 1
1954 && GET_CODE (range1end) == JUMP_INSN
1955 && simplejump_p (range1end))
1957 rtx label2 = next_label (label1);
1958 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1959 if (range1end != range2end
1960 && JUMP_LABEL (range1end) == label2
1961 && GET_CODE (range2end) == JUMP_INSN
1962 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1963 /* Invert the jump condition, so we
1964 still execute the same insns in each case. */
1965 && invert_jump (insn, label1))
1967 rtx range1beg = next_active_insn (insn);
1968 rtx range2beg = next_active_insn (label1);
1969 rtx range1after, range2after;
1970 rtx range1before, range2before;
1973 /* Include in each range any notes before it, to be
1974 sure that we get the line number note if any, even
1975 if there are other notes here. */
1976 while (PREV_INSN (range1beg)
1977 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1978 range1beg = PREV_INSN (range1beg);
1980 while (PREV_INSN (range2beg)
1981 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1982 range2beg = PREV_INSN (range2beg);
1984 /* Don't move NOTEs for blocks or loops; shift them
1985 outside the ranges, where they'll stay put. */
1986 range1beg = squeeze_notes (range1beg, range1end);
1987 range2beg = squeeze_notes (range2beg, range2end);
1989 /* Get current surrounds of the 2 ranges. */
1990 range1before = PREV_INSN (range1beg);
1991 range2before = PREV_INSN (range2beg);
1992 range1after = NEXT_INSN (range1end);
1993 range2after = NEXT_INSN (range2end);
1995 /* Splice range2 where range1 was. */
1996 NEXT_INSN (range1before) = range2beg;
1997 PREV_INSN (range2beg) = range1before;
1998 NEXT_INSN (range2end) = range1after;
1999 PREV_INSN (range1after) = range2end;
2000 /* Splice range1 where range2 was. */
2001 NEXT_INSN (range2before) = range1beg;
2002 PREV_INSN (range1beg) = range2before;
2003 NEXT_INSN (range1end) = range2after;
2004 PREV_INSN (range2after) = range1end;
2006 /* Check for a loop end note between the end of
2007 range2, and the next code label. If there is one,
2008 then what we have really seen is
2009 if (foo) break; end_of_loop;
2010 and moved the break sequence outside the loop.
2011 We must move the LOOP_END note to where the
2012 loop really ends now, or we will confuse loop
2013 optimization. Stop if we find a LOOP_BEG note
2014 first, since we don't want to move the LOOP_END
2015 note in that case. */
2016 for (;range2after != label2; range2after = rangenext)
2018 rangenext = NEXT_INSN (range2after);
2019 if (GET_CODE (range2after) == NOTE)
2021 if (NOTE_LINE_NUMBER (range2after)
2022 == NOTE_INSN_LOOP_END)
2024 NEXT_INSN (PREV_INSN (range2after))
2026 PREV_INSN (rangenext)
2027 = PREV_INSN (range2after);
2028 PREV_INSN (range2after)
2029 = PREV_INSN (range1beg);
2030 NEXT_INSN (range2after) = range1beg;
2031 NEXT_INSN (PREV_INSN (range1beg))
2033 PREV_INSN (range1beg) = range2after;
2035 else if (NOTE_LINE_NUMBER (range2after)
2036 == NOTE_INSN_LOOP_BEG)
2046 /* Now that the jump has been tensioned,
2047 try cross jumping: check for identical code
2048 before the jump and before its target label. */
2050 /* First, cross jumping of conditional jumps: */
2052 if (cross_jump && condjump_p (insn))
2054 rtx newjpos, newlpos;
2055 rtx x = prev_real_insn (JUMP_LABEL (insn));
2057 /* A conditional jump may be crossjumped
2058 only if the place it jumps to follows
2059 an opposing jump that comes back here. */
2061 if (x != 0 && ! jump_back_p (x, insn))
2062 /* We have no opposing jump;
2063 cannot cross jump this insn. */
2067 /* TARGET is nonzero if it is ok to cross jump
2068 to code before TARGET. If so, see if matches. */
2070 find_cross_jump (insn, x, 2,
2071 &newjpos, &newlpos);
2075 do_cross_jump (insn, newjpos, newlpos);
2076 /* Make the old conditional jump
2077 into an unconditional one. */
2078 SET_SRC (PATTERN (insn))
2079 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
2080 INSN_CODE (insn) = -1;
2081 emit_barrier_after (insn);
2082 /* Add to jump_chain unless this is a new label
2083 whose UID is too large. */
2084 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
2086 jump_chain[INSN_UID (insn)]
2087 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2088 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2095 /* Cross jumping of unconditional jumps:
2096 a few differences. */
2098 if (cross_jump && simplejump_p (insn))
2100 rtx newjpos, newlpos;
2105 /* TARGET is nonzero if it is ok to cross jump
2106 to code before TARGET. If so, see if matches. */
2107 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2108 &newjpos, &newlpos);
2110 /* If cannot cross jump to code before the label,
2111 see if we can cross jump to another jump to
2113 /* Try each other jump to this label. */
2114 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2115 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2116 target != 0 && newjpos == 0;
2117 target = jump_chain[INSN_UID (target)])
2119 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2120 /* Ignore TARGET if it's deleted. */
2121 && ! INSN_DELETED_P (target))
2122 find_cross_jump (insn, target, 2,
2123 &newjpos, &newlpos);
2127 do_cross_jump (insn, newjpos, newlpos);
2133 /* This code was dead in the previous jump.c! */
2134 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2136 /* Return insns all "jump to the same place"
2137 so we can cross-jump between any two of them. */
2139 rtx newjpos, newlpos, target;
2143 /* If cannot cross jump to code before the label,
2144 see if we can cross jump to another jump to
2146 /* Try each other jump to this label. */
2147 for (target = jump_chain[0];
2148 target != 0 && newjpos == 0;
2149 target = jump_chain[INSN_UID (target)])
2151 && ! INSN_DELETED_P (target)
2152 && GET_CODE (PATTERN (target)) == RETURN)
2153 find_cross_jump (insn, target, 2,
2154 &newjpos, &newlpos);
2158 do_cross_jump (insn, newjpos, newlpos);
2169 /* Delete extraneous line number notes.
2170 Note that two consecutive notes for different lines are not really
2171 extraneous. There should be some indication where that line belonged,
2172 even if it became empty. */
2177 for (insn = f; insn; insn = NEXT_INSN (insn))
2178 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2180 /* Delete this note if it is identical to previous note. */
2182 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2183 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2196 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2197 in front of it. If the machine allows it at this point (we might be
2198 after reload for a leaf routine), it will improve optimization for it
2199 to be there. We do this both here and at the start of this pass since
2200 the RETURN might have been deleted by some of our optimizations. */
2201 insn = get_last_insn ();
2202 while (insn && GET_CODE (insn) == NOTE)
2203 insn = PREV_INSN (insn);
2205 if (insn && GET_CODE (insn) != BARRIER)
2207 emit_jump_insn (gen_return ());
2213 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2214 If so, delete it, and record that this function can drop off the end. */
2220 /* One label can follow the end-note: the return label. */
2221 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2222 /* Ordinary insns can follow it if returning a structure. */
2223 || GET_CODE (insn) == INSN
2224 /* If machine uses explicit RETURN insns, no epilogue,
2225 then one of them follows the note. */
2226 || (GET_CODE (insn) == JUMP_INSN
2227 && GET_CODE (PATTERN (insn)) == RETURN)
2228 /* A barrier can follow the return insn. */
2229 || GET_CODE (insn) == BARRIER
2230 /* Other kinds of notes can follow also. */
2231 || (GET_CODE (insn) == NOTE
2232 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2233 insn = PREV_INSN (insn);
2236 /* Report if control can fall through at the end of the function. */
2237 if (insn && GET_CODE (insn) == NOTE
2238 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2244 /* Show JUMP_CHAIN no longer valid. */
2248 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2249 jump. Assume that this unconditional jump is to the exit test code. If
2250 the code is sufficiently simple, make a copy of it before INSN,
2251 followed by a jump to the exit of the loop. Then delete the unconditional
2254 Return 1 if we made the change, else 0.
2256 This is only safe immediately after a regscan pass because it uses the
2257 values of regno_first_uid and regno_last_uid. */
2260 duplicate_loop_exit_test (loop_start)
2263 rtx insn, set, reg, p, link;
2266 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2268 int max_reg = max_reg_num ();
2271 /* Scan the exit code. We do not perform this optimization if any insn:
2275 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2276 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2277 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2280 Also, don't do this if the exit code is more than 20 insns. */
2282 for (insn = exitcode;
2284 && ! (GET_CODE (insn) == NOTE
2285 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2286 insn = NEXT_INSN (insn))
2288 switch (GET_CODE (insn))
2294 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2295 a jump immediately after the loop start that branches outside
2296 the loop but within an outer loop, near the exit test.
2297 If we copied this exit test and created a phony
2298 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2299 before the exit test look like these could be safely moved
2300 out of the loop even if they actually may be never executed.
2301 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2303 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2304 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2305 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2306 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2311 if (++num_insns > 20
2312 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2313 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2319 /* Unless INSN is zero, we can do the optimization. */
2325 /* See if any insn sets a register only used in the loop exit code and
2326 not a user variable. If so, replace it with a new register. */
2327 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2328 if (GET_CODE (insn) == INSN
2329 && (set = single_set (insn)) != 0
2330 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2331 || (GET_CODE (reg) == SUBREG
2332 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2333 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2334 && regno_first_uid[REGNO (reg)] == INSN_UID (insn))
2336 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2337 if (regno_last_uid[REGNO (reg)] == INSN_UID (p))
2342 /* We can do the replacement. Allocate reg_map if this is the
2343 first replacement we found. */
2346 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2347 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2350 REG_LOOP_TEST_P (reg) = 1;
2352 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2356 /* Now copy each insn. */
2357 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2358 switch (GET_CODE (insn))
2361 copy = emit_barrier_before (loop_start);
2364 /* Only copy line-number notes. */
2365 if (NOTE_LINE_NUMBER (insn) >= 0)
2367 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2368 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2373 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2375 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2377 mark_jump_label (PATTERN (copy), copy, 0);
2379 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2381 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2382 if (REG_NOTE_KIND (link) != REG_LABEL)
2384 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
2385 XEXP (link, 0), REG_NOTES (copy)));
2386 if (reg_map && REG_NOTES (copy))
2387 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2391 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2393 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2394 mark_jump_label (PATTERN (copy), copy, 0);
2395 if (REG_NOTES (insn))
2397 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2399 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2402 /* If this is a simple jump, add it to the jump chain. */
2404 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2405 && simplejump_p (copy))
2407 jump_chain[INSN_UID (copy)]
2408 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2409 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2417 /* Now clean up by emitting a jump to the end label and deleting the jump
2418 at the start of the loop. */
2419 if (! copy || GET_CODE (copy) != BARRIER)
2421 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2423 mark_jump_label (PATTERN (copy), copy, 0);
2424 if (INSN_UID (copy) < max_jump_chain
2425 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2427 jump_chain[INSN_UID (copy)]
2428 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2429 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2431 emit_barrier_before (loop_start);
2434 /* Mark the exit code as the virtual top of the converted loop. */
2435 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2437 delete_insn (next_nonnote_insn (loop_start));
2442 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2443 loop-end notes between START and END out before START. Assume that
2444 END is not such a note. START may be such a note. Returns the value
2445 of the new starting insn, which may be different if the original start
2449 squeeze_notes (start, end)
2455 for (insn = start; insn != end; insn = next)
2457 next = NEXT_INSN (insn);
2458 if (GET_CODE (insn) == NOTE
2459 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2460 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2461 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2462 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2463 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2464 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2470 rtx prev = PREV_INSN (insn);
2471 PREV_INSN (insn) = PREV_INSN (start);
2472 NEXT_INSN (insn) = start;
2473 NEXT_INSN (PREV_INSN (insn)) = insn;
2474 PREV_INSN (NEXT_INSN (insn)) = insn;
2475 NEXT_INSN (prev) = next;
2476 PREV_INSN (next) = prev;
2484 /* Compare the instructions before insn E1 with those before E2
2485 to find an opportunity for cross jumping.
2486 (This means detecting identical sequences of insns followed by
2487 jumps to the same place, or followed by a label and a jump
2488 to that label, and replacing one with a jump to the other.)
2490 Assume E1 is a jump that jumps to label E2
2491 (that is not always true but it might as well be).
2492 Find the longest possible equivalent sequences
2493 and store the first insns of those sequences into *F1 and *F2.
2494 Store zero there if no equivalent preceding instructions are found.
2496 We give up if we find a label in stream 1.
2497 Actually we could transfer that label into stream 2. */
2500 find_cross_jump (e1, e2, minimum, f1, f2)
2505 register rtx i1 = e1, i2 = e2;
2506 register rtx p1, p2;
2509 rtx last1 = 0, last2 = 0;
2510 rtx afterlast1 = 0, afterlast2 = 0;
2518 i1 = prev_nonnote_insn (i1);
2520 i2 = PREV_INSN (i2);
2521 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2522 i2 = PREV_INSN (i2);
2527 /* Don't allow the range of insns preceding E1 or E2
2528 to include the other (E2 or E1). */
2529 if (i2 == e1 || i1 == e2)
2532 /* If we will get to this code by jumping, those jumps will be
2533 tensioned to go directly to the new label (before I2),
2534 so this cross-jumping won't cost extra. So reduce the minimum. */
2535 if (GET_CODE (i1) == CODE_LABEL)
2541 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2547 /* If this is a CALL_INSN, compare register usage information.
2548 If we don't check this on stack register machines, the two
2549 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2550 numbers of stack registers in the same basic block.
2551 If we don't check this on machines with delay slots, a delay slot may
2552 be filled that clobbers a parameter expected by the subroutine.
2554 ??? We take the simple route for now and assume that if they're
2555 equal, they were constructed identically. */
2557 if (GET_CODE (i1) == CALL_INSN
2558 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2559 CALL_INSN_FUNCTION_USAGE (i2)))
2563 /* If cross_jump_death_matters is not 0, the insn's mode
2564 indicates whether or not the insn contains any stack-like
2567 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2569 /* If register stack conversion has already been done, then
2570 death notes must also be compared before it is certain that
2571 the two instruction streams match. */
2574 HARD_REG_SET i1_regset, i2_regset;
2576 CLEAR_HARD_REG_SET (i1_regset);
2577 CLEAR_HARD_REG_SET (i2_regset);
2579 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2580 if (REG_NOTE_KIND (note) == REG_DEAD
2581 && STACK_REG_P (XEXP (note, 0)))
2582 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2584 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2585 if (REG_NOTE_KIND (note) == REG_DEAD
2586 && STACK_REG_P (XEXP (note, 0)))
2587 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2589 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2598 if (lose || GET_CODE (p1) != GET_CODE (p2)
2599 || ! rtx_renumbered_equal_p (p1, p2))
2601 /* The following code helps take care of G++ cleanups. */
2605 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2606 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2607 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2608 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2609 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2610 /* If the equivalences are not to a constant, they may
2611 reference pseudos that no longer exist, so we can't
2613 && CONSTANT_P (XEXP (equiv1, 0))
2614 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2616 rtx s1 = single_set (i1);
2617 rtx s2 = single_set (i2);
2618 if (s1 != 0 && s2 != 0
2619 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2621 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2622 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2623 if (! rtx_renumbered_equal_p (p1, p2))
2625 else if (apply_change_group ())
2630 /* Insns fail to match; cross jumping is limited to the following
2634 /* Don't allow the insn after a compare to be shared by
2635 cross-jumping unless the compare is also shared.
2636 Here, if either of these non-matching insns is a compare,
2637 exclude the following insn from possible cross-jumping. */
2638 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2639 last1 = afterlast1, last2 = afterlast2, ++minimum;
2642 /* If cross-jumping here will feed a jump-around-jump
2643 optimization, this jump won't cost extra, so reduce
2645 if (GET_CODE (i1) == JUMP_INSN
2647 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2653 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2655 /* Ok, this insn is potentially includable in a cross-jump here. */
2656 afterlast1 = last1, afterlast2 = last2;
2657 last1 = i1, last2 = i2, --minimum;
2661 if (minimum <= 0 && last1 != 0 && last1 != e1)
2662 *f1 = last1, *f2 = last2;
2666 do_cross_jump (insn, newjpos, newlpos)
2667 rtx insn, newjpos, newlpos;
2669 /* Find an existing label at this point
2670 or make a new one if there is none. */
2671 register rtx label = get_label_before (newlpos);
2673 /* Make the same jump insn jump to the new point. */
2674 if (GET_CODE (PATTERN (insn)) == RETURN)
2676 /* Remove from jump chain of returns. */
2677 delete_from_jump_chain (insn);
2678 /* Change the insn. */
2679 PATTERN (insn) = gen_jump (label);
2680 INSN_CODE (insn) = -1;
2681 JUMP_LABEL (insn) = label;
2682 LABEL_NUSES (label)++;
2683 /* Add to new the jump chain. */
2684 if (INSN_UID (label) < max_jump_chain
2685 && INSN_UID (insn) < max_jump_chain)
2687 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2688 jump_chain[INSN_UID (label)] = insn;
2692 redirect_jump (insn, label);
2694 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2695 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2696 the NEWJPOS stream. */
2698 while (newjpos != insn)
2702 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2703 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2704 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2705 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2706 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2707 remove_note (newlpos, lnote);
2709 delete_insn (newjpos);
2710 newjpos = next_real_insn (newjpos);
2711 newlpos = next_real_insn (newlpos);
2715 /* Return the label before INSN, or put a new label there. */
2718 get_label_before (insn)
2723 /* Find an existing label at this point
2724 or make a new one if there is none. */
2725 label = prev_nonnote_insn (insn);
2727 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2729 rtx prev = PREV_INSN (insn);
2731 label = gen_label_rtx ();
2732 emit_label_after (label, prev);
2733 LABEL_NUSES (label) = 0;
2738 /* Return the label after INSN, or put a new label there. */
2741 get_label_after (insn)
2746 /* Find an existing label at this point
2747 or make a new one if there is none. */
2748 label = next_nonnote_insn (insn);
2750 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2752 label = gen_label_rtx ();
2753 emit_label_after (label, insn);
2754 LABEL_NUSES (label) = 0;
2759 /* Return 1 if INSN is a jump that jumps to right after TARGET
2760 only on the condition that TARGET itself would drop through.
2761 Assumes that TARGET is a conditional jump. */
2764 jump_back_p (insn, target)
2768 enum rtx_code codei, codet;
2770 if (simplejump_p (insn) || ! condjump_p (insn)
2771 || simplejump_p (target)
2772 || target != prev_real_insn (JUMP_LABEL (insn)))
2775 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2776 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2778 codei = GET_CODE (cinsn);
2779 codet = GET_CODE (ctarget);
2781 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2783 if (! can_reverse_comparison_p (cinsn, insn))
2785 codei = reverse_condition (codei);
2788 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2790 if (! can_reverse_comparison_p (ctarget, target))
2792 codet = reverse_condition (codet);
2795 return (codei == codet
2796 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2797 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2800 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2801 return non-zero if it is safe to reverse this comparison. It is if our
2802 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2803 this is known to be an integer comparison. */
2806 can_reverse_comparison_p (comparison, insn)
2812 /* If this is not actually a comparison, we can't reverse it. */
2813 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2816 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2817 /* If this is an NE comparison, it is safe to reverse it to an EQ
2818 comparison and vice versa, even for floating point. If no operands
2819 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2820 always false and NE is always true, so the reversal is also valid. */
2822 || GET_CODE (comparison) == NE
2823 || GET_CODE (comparison) == EQ)
2826 arg0 = XEXP (comparison, 0);
2828 /* Make sure ARG0 is one of the actual objects being compared. If we
2829 can't do this, we can't be sure the comparison can be reversed.
2831 Handle cc0 and a MODE_CC register. */
2832 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2838 rtx prev = prev_nonnote_insn (insn);
2839 rtx set = single_set (prev);
2841 if (set == 0 || SET_DEST (set) != arg0)
2844 arg0 = SET_SRC (set);
2846 if (GET_CODE (arg0) == COMPARE)
2847 arg0 = XEXP (arg0, 0);
2850 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2851 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2852 return (GET_CODE (arg0) == CONST_INT
2853 || (GET_MODE (arg0) != VOIDmode
2854 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2855 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2858 /* Given an rtx-code for a comparison, return the code
2859 for the negated comparison.
2860 WATCH OUT! reverse_condition is not safe to use on a jump
2861 that might be acting on the results of an IEEE floating point comparison,
2862 because of the special treatment of non-signaling nans in comparisons.
2863 Use can_reverse_comparison_p to be sure. */
2866 reverse_condition (code)
2907 /* Similar, but return the code when two operands of a comparison are swapped.
2908 This IS safe for IEEE floating-point. */
2911 swap_condition (code)
2950 /* Given a comparison CODE, return the corresponding unsigned comparison.
2951 If CODE is an equality comparison or already an unsigned comparison,
2952 CODE is returned. */
2955 unsigned_condition (code)
2985 /* Similarly, return the signed version of a comparison. */
2988 signed_condition (code)
3018 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3019 truth of CODE1 implies the truth of CODE2. */
3022 comparison_dominates_p (code1, code2)
3023 enum rtx_code code1, code2;
3031 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3036 if (code2 == LE || code2 == NE)
3041 if (code2 == GE || code2 == NE)
3046 if (code2 == LEU || code2 == NE)
3051 if (code2 == GEU || code2 == NE)
3059 /* Return 1 if INSN is an unconditional jump and nothing else. */
3065 return (GET_CODE (insn) == JUMP_INSN
3066 && GET_CODE (PATTERN (insn)) == SET
3067 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3068 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3071 /* Return nonzero if INSN is a (possibly) conditional jump
3072 and nothing more. */
3078 register rtx x = PATTERN (insn);
3079 if (GET_CODE (x) != SET)
3081 if (GET_CODE (SET_DEST (x)) != PC)
3083 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3085 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3087 if (XEXP (SET_SRC (x), 2) == pc_rtx
3088 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3089 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3091 if (XEXP (SET_SRC (x), 1) == pc_rtx
3092 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3093 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3098 /* Return nonzero if INSN is a (possibly) conditional jump
3099 and nothing more. */
3102 condjump_in_parallel_p (insn)
3105 register rtx x = PATTERN (insn);
3107 if (GET_CODE (x) != PARALLEL)
3110 x = XVECEXP (x, 0, 0);
3112 if (GET_CODE (x) != SET)
3114 if (GET_CODE (SET_DEST (x)) != PC)
3116 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3118 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3120 if (XEXP (SET_SRC (x), 2) == pc_rtx
3121 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3122 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3124 if (XEXP (SET_SRC (x), 1) == pc_rtx
3125 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3126 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3131 /* Return 1 if X is an RTX that does nothing but set the condition codes
3132 and CLOBBER or USE registers.
3133 Return -1 if X does explicitly set the condition codes,
3134 but also does other things. */
3141 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3143 if (GET_CODE (x) == PARALLEL)
3147 int other_things = 0;
3148 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3150 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3151 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3153 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3156 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3164 /* Follow any unconditional jump at LABEL;
3165 return the ultimate label reached by any such chain of jumps.
3166 If LABEL is not followed by a jump, return LABEL.
3167 If the chain loops or we can't find end, return LABEL,
3168 since that tells caller to avoid changing the insn.
3170 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3171 a USE or CLOBBER. */
3174 follow_jumps (label)
3179 register rtx value = label;
3184 && (insn = next_active_insn (value)) != 0
3185 && GET_CODE (insn) == JUMP_INSN
3186 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3187 || GET_CODE (PATTERN (insn)) == RETURN)
3188 && (next = NEXT_INSN (insn))
3189 && GET_CODE (next) == BARRIER);
3192 /* Don't chain through the insn that jumps into a loop
3193 from outside the loop,
3194 since that would create multiple loop entry jumps
3195 and prevent loop optimization. */
3197 if (!reload_completed)
3198 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3199 if (GET_CODE (tem) == NOTE
3200 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
3203 /* If we have found a cycle, make the insn jump to itself. */
3204 if (JUMP_LABEL (insn) == label)
3207 tem = next_active_insn (JUMP_LABEL (insn));
3208 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3209 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3212 value = JUMP_LABEL (insn);
3219 /* Assuming that field IDX of X is a vector of label_refs,
3220 replace each of them by the ultimate label reached by it.
3221 Return nonzero if a change is made.
3222 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3225 tension_vector_labels (x, idx)
3231 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3233 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3234 register rtx nlabel = follow_jumps (olabel);
3235 if (nlabel && nlabel != olabel)
3237 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3238 ++LABEL_NUSES (nlabel);
3239 if (--LABEL_NUSES (olabel) == 0)
3240 delete_insn (olabel);
3247 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3248 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3249 in INSN, then store one of them in JUMP_LABEL (INSN).
3250 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3251 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3252 Also, when there are consecutive labels, canonicalize on the last of them.
3254 Note that two labels separated by a loop-beginning note
3255 must be kept distinct if we have not yet done loop-optimization,
3256 because the gap between them is where loop-optimize
3257 will want to move invariant code to. CROSS_JUMP tells us
3258 that loop-optimization is done with.
3260 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3261 two labels distinct if they are separated by only USE or CLOBBER insns. */
3264 mark_jump_label (x, insn, cross_jump)
3269 register RTX_CODE code = GET_CODE (x);
3287 /* If this is a constant-pool reference, see if it is a label. */
3288 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3289 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3290 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3295 rtx label = XEXP (x, 0);
3300 if (GET_CODE (label) != CODE_LABEL)
3303 /* Ignore references to labels of containing functions. */
3304 if (LABEL_REF_NONLOCAL_P (x))
3307 /* If there are other labels following this one,
3308 replace it with the last of the consecutive labels. */
3309 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3311 if (GET_CODE (next) == CODE_LABEL)
3313 else if (cross_jump && GET_CODE (next) == INSN
3314 && (GET_CODE (PATTERN (next)) == USE
3315 || GET_CODE (PATTERN (next)) == CLOBBER))
3317 else if (GET_CODE (next) != NOTE)
3319 else if (! cross_jump
3320 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3321 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
3325 XEXP (x, 0) = label;
3326 ++LABEL_NUSES (label);
3330 if (GET_CODE (insn) == JUMP_INSN)
3331 JUMP_LABEL (insn) = label;
3333 /* If we've changed OLABEL and we had a REG_LABEL note
3334 for it, update it as well. */
3335 else if (label != olabel
3336 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3337 XEXP (note, 0) = label;
3339 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3341 else if (! find_reg_note (insn, REG_LABEL, label))
3343 rtx next = next_real_insn (label);
3344 /* Don't record labels that refer to dispatch tables.
3345 This is not necessary, since the tablejump
3346 references the same label.
3347 And if we did record them, flow.c would make worse code. */
3349 || ! (GET_CODE (next) == JUMP_INSN
3350 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3351 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
3352 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
3359 /* Do walk the labels in a vector, but not the first operand of an
3360 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3364 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3366 for (i = 0; i < XVECLEN (x, eltnum); i++)
3367 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3372 fmt = GET_RTX_FORMAT (code);
3373 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3376 mark_jump_label (XEXP (x, i), insn, cross_jump);
3377 else if (fmt[i] == 'E')
3380 for (j = 0; j < XVECLEN (x, i); j++)
3381 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3386 /* If all INSN does is set the pc, delete it,
3387 and delete the insn that set the condition codes for it
3388 if that's what the previous thing was. */
3394 register rtx set = single_set (insn);
3396 if (set && GET_CODE (SET_DEST (set)) == PC)
3397 delete_computation (insn);
3400 /* Delete INSN and recursively delete insns that compute values used only
3401 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3402 If we are running before flow.c, we need do nothing since flow.c will
3403 delete dead code. We also can't know if the registers being used are
3404 dead or not at this point.
3406 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3407 nothing other than set a register that dies in this insn, we can delete
3410 On machines with CC0, if CC0 is used in this insn, we may be able to
3411 delete the insn that set it. */
3414 delete_computation (insn)
3420 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3422 rtx prev = prev_nonnote_insn (insn);
3423 /* We assume that at this stage
3424 CC's are always set explicitly
3425 and always immediately before the jump that
3426 will use them. So if the previous insn
3427 exists to set the CC's, delete it
3428 (unless it performs auto-increments, etc.). */
3429 if (prev && GET_CODE (prev) == INSN
3430 && sets_cc0_p (PATTERN (prev)))
3432 if (sets_cc0_p (PATTERN (prev)) > 0
3433 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3434 delete_computation (prev);
3436 /* Otherwise, show that cc0 won't be used. */
3437 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
3438 cc0_rtx, REG_NOTES (prev));
3443 for (note = REG_NOTES (insn); note; note = next)
3447 next = XEXP (note, 1);
3449 if (REG_NOTE_KIND (note) != REG_DEAD
3450 /* Verify that the REG_NOTE is legitimate. */
3451 || GET_CODE (XEXP (note, 0)) != REG)
3454 for (our_prev = prev_nonnote_insn (insn);
3455 our_prev && GET_CODE (our_prev) == INSN;
3456 our_prev = prev_nonnote_insn (our_prev))
3458 /* If we reach a SEQUENCE, it is too complex to try to
3459 do anything with it, so give up. */
3460 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3463 if (GET_CODE (PATTERN (our_prev)) == USE
3464 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3465 /* reorg creates USEs that look like this. We leave them
3466 alone because reorg needs them for its own purposes. */
3469 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3471 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3474 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3476 /* If we find a SET of something else, we can't
3481 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3483 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3485 if (GET_CODE (part) == SET
3486 && SET_DEST (part) != XEXP (note, 0))
3490 if (i == XVECLEN (PATTERN (our_prev), 0))
3491 delete_computation (our_prev);
3493 else if (GET_CODE (PATTERN (our_prev)) == SET
3494 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3495 delete_computation (our_prev);
3500 /* If OUR_PREV references the register that dies here, it is an
3501 additional use. Hence any prior SET isn't dead. However, this
3502 insn becomes the new place for the REG_DEAD note. */
3503 if (reg_overlap_mentioned_p (XEXP (note, 0),
3504 PATTERN (our_prev)))
3506 XEXP (note, 1) = REG_NOTES (our_prev);
3507 REG_NOTES (our_prev) = note;
3516 /* Delete insn INSN from the chain of insns and update label ref counts.
3517 May delete some following insns as a consequence; may even delete
3518 a label elsewhere and insns that follow it.
3520 Returns the first insn after INSN that was not deleted. */
3526 register rtx next = NEXT_INSN (insn);
3527 register rtx prev = PREV_INSN (insn);
3528 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3529 register int dont_really_delete = 0;
3531 while (next && INSN_DELETED_P (next))
3532 next = NEXT_INSN (next);
3534 /* This insn is already deleted => return first following nondeleted. */
3535 if (INSN_DELETED_P (insn))
3538 /* Don't delete user-declared labels. Convert them to special NOTEs
3540 if (was_code_label && LABEL_NAME (insn) != 0
3541 && optimize && ! dont_really_delete)
3543 PUT_CODE (insn, NOTE);
3544 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3545 NOTE_SOURCE_FILE (insn) = 0;
3546 dont_really_delete = 1;
3549 /* Mark this insn as deleted. */
3550 INSN_DELETED_P (insn) = 1;
3552 /* If this is an unconditional jump, delete it from the jump chain. */
3553 if (simplejump_p (insn))
3554 delete_from_jump_chain (insn);
3556 /* If instruction is followed by a barrier,
3557 delete the barrier too. */
3559 if (next != 0 && GET_CODE (next) == BARRIER)
3561 INSN_DELETED_P (next) = 1;
3562 next = NEXT_INSN (next);
3565 /* Patch out INSN (and the barrier if any) */
3567 if (optimize && ! dont_really_delete)
3571 NEXT_INSN (prev) = next;
3572 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3573 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3574 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3579 PREV_INSN (next) = prev;
3580 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3581 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3584 if (prev && NEXT_INSN (prev) == 0)
3585 set_last_insn (prev);
3588 /* If deleting a jump, decrement the count of the label,
3589 and delete the label if it is now unused. */
3591 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3592 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3594 /* This can delete NEXT or PREV,
3595 either directly if NEXT is JUMP_LABEL (INSN),
3596 or indirectly through more levels of jumps. */
3597 delete_insn (JUMP_LABEL (insn));
3598 /* I feel a little doubtful about this loop,
3599 but I see no clean and sure alternative way
3600 to find the first insn after INSN that is not now deleted.
3601 I hope this works. */
3602 while (next && INSN_DELETED_P (next))
3603 next = NEXT_INSN (next);
3607 /* Likewise if we're deleting a dispatch table. */
3609 if (GET_CODE (insn) == JUMP_INSN
3610 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3611 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3613 rtx pat = PATTERN (insn);
3614 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3615 int len = XVECLEN (pat, diff_vec_p);
3617 for (i = 0; i < len; i++)
3618 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3619 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3620 while (next && INSN_DELETED_P (next))
3621 next = NEXT_INSN (next);
3625 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3626 prev = PREV_INSN (prev);
3628 /* If INSN was a label and a dispatch table follows it,
3629 delete the dispatch table. The tablejump must have gone already.
3630 It isn't useful to fall through into a table. */
3633 && NEXT_INSN (insn) != 0
3634 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3635 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3636 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3637 next = delete_insn (NEXT_INSN (insn));
3639 /* If INSN was a label, delete insns following it if now unreachable. */
3641 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3643 register RTX_CODE code;
3645 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3646 || code == NOTE || code == BARRIER
3647 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3650 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3651 next = NEXT_INSN (next);
3652 /* Keep going past other deleted labels to delete what follows. */
3653 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3654 next = NEXT_INSN (next);
3656 /* Note: if this deletes a jump, it can cause more
3657 deletion of unreachable code, after a different label.
3658 As long as the value from this recursive call is correct,
3659 this invocation functions correctly. */
3660 next = delete_insn (next);
3667 /* Advance from INSN till reaching something not deleted
3668 then return that. May return INSN itself. */
3671 next_nondeleted_insn (insn)
3674 while (INSN_DELETED_P (insn))
3675 insn = NEXT_INSN (insn);
3679 /* Delete a range of insns from FROM to TO, inclusive.
3680 This is for the sake of peephole optimization, so assume
3681 that whatever these insns do will still be done by a new
3682 peephole insn that will replace them. */
3685 delete_for_peephole (from, to)
3686 register rtx from, to;
3688 register rtx insn = from;
3692 register rtx next = NEXT_INSN (insn);
3693 register rtx prev = PREV_INSN (insn);
3695 if (GET_CODE (insn) != NOTE)
3697 INSN_DELETED_P (insn) = 1;
3699 /* Patch this insn out of the chain. */
3700 /* We don't do this all at once, because we
3701 must preserve all NOTEs. */
3703 NEXT_INSN (prev) = next;
3706 PREV_INSN (next) = prev;
3714 /* Note that if TO is an unconditional jump
3715 we *do not* delete the BARRIER that follows,
3716 since the peephole that replaces this sequence
3717 is also an unconditional jump in that case. */
3720 /* Invert the condition of the jump JUMP, and make it jump
3721 to label NLABEL instead of where it jumps now. */
3724 invert_jump (jump, nlabel)
3727 /* We have to either invert the condition and change the label or
3728 do neither. Either operation could fail. We first try to invert
3729 the jump. If that succeeds, we try changing the label. If that fails,
3730 we invert the jump back to what it was. */
3732 if (! invert_exp (PATTERN (jump), jump))
3735 if (redirect_jump (jump, nlabel))
3738 if (! invert_exp (PATTERN (jump), jump))
3739 /* This should just be putting it back the way it was. */
3745 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3747 Return 1 if we can do so, 0 if we cannot find a way to do so that
3748 matches a pattern. */
3751 invert_exp (x, insn)
3755 register RTX_CODE code;
3759 code = GET_CODE (x);
3761 if (code == IF_THEN_ELSE)
3763 register rtx comp = XEXP (x, 0);
3766 /* We can do this in two ways: The preferable way, which can only
3767 be done if this is not an integer comparison, is to reverse
3768 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3769 of the IF_THEN_ELSE. If we can't do either, fail. */
3771 if (can_reverse_comparison_p (comp, insn)
3772 && validate_change (insn, &XEXP (x, 0),
3773 gen_rtx (reverse_condition (GET_CODE (comp)),
3774 GET_MODE (comp), XEXP (comp, 0),
3775 XEXP (comp, 1)), 0))
3779 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3780 validate_change (insn, &XEXP (x, 2), tem, 1);
3781 return apply_change_group ();
3784 fmt = GET_RTX_FORMAT (code);
3785 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3788 if (! invert_exp (XEXP (x, i), insn))
3793 for (j = 0; j < XVECLEN (x, i); j++)
3794 if (!invert_exp (XVECEXP (x, i, j), insn))
3802 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3803 If the old jump target label is unused as a result,
3804 it and the code following it may be deleted.
3806 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3809 The return value will be 1 if the change was made, 0 if it wasn't (this
3810 can only occur for NLABEL == 0). */
3813 redirect_jump (jump, nlabel)
3816 register rtx olabel = JUMP_LABEL (jump);
3818 if (nlabel == olabel)
3821 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3824 /* If this is an unconditional branch, delete it from the jump_chain of
3825 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3826 have UID's in range and JUMP_CHAIN is valid). */
3827 if (jump_chain && (simplejump_p (jump)
3828 || GET_CODE (PATTERN (jump)) == RETURN))
3830 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3832 delete_from_jump_chain (jump);
3833 if (label_index < max_jump_chain
3834 && INSN_UID (jump) < max_jump_chain)
3836 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3837 jump_chain[label_index] = jump;
3841 JUMP_LABEL (jump) = nlabel;
3843 ++LABEL_NUSES (nlabel);
3845 if (olabel && --LABEL_NUSES (olabel) == 0)
3846 delete_insn (olabel);
3851 /* Delete the instruction JUMP from any jump chain it might be on. */
3854 delete_from_jump_chain (jump)
3858 rtx olabel = JUMP_LABEL (jump);
3860 /* Handle unconditional jumps. */
3861 if (jump_chain && olabel != 0
3862 && INSN_UID (olabel) < max_jump_chain
3863 && simplejump_p (jump))
3864 index = INSN_UID (olabel);
3865 /* Handle return insns. */
3866 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3870 if (jump_chain[index] == jump)
3871 jump_chain[index] = jump_chain[INSN_UID (jump)];
3876 for (insn = jump_chain[index];
3878 insn = jump_chain[INSN_UID (insn)])
3879 if (jump_chain[INSN_UID (insn)] == jump)
3881 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3887 /* If NLABEL is nonzero, throughout the rtx at LOC,
3888 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3889 zero, alter (RETURN) to (LABEL_REF NLABEL).
3891 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3892 validity with validate_change. Convert (set (pc) (label_ref olabel))
3895 Return 0 if we found a change we would like to make but it is invalid.
3896 Otherwise, return 1. */
3899 redirect_exp (loc, olabel, nlabel, insn)
3904 register rtx x = *loc;
3905 register RTX_CODE code = GET_CODE (x);
3909 if (code == LABEL_REF)
3911 if (XEXP (x, 0) == olabel)
3914 XEXP (x, 0) = nlabel;
3916 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3920 else if (code == RETURN && olabel == 0)
3922 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3923 if (loc == &PATTERN (insn))
3924 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3925 return validate_change (insn, loc, x, 0);
3928 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3929 && GET_CODE (SET_SRC (x)) == LABEL_REF
3930 && XEXP (SET_SRC (x), 0) == olabel)
3931 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3933 fmt = GET_RTX_FORMAT (code);
3934 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3937 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3942 for (j = 0; j < XVECLEN (x, i); j++)
3943 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3951 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3953 If the old jump target label (before the dispatch table) becomes unused,
3954 it and the dispatch table may be deleted. In that case, find the insn
3955 before the jump references that label and delete it and logical successors
3959 redirect_tablejump (jump, nlabel)
3962 register rtx olabel = JUMP_LABEL (jump);
3964 /* Add this jump to the jump_chain of NLABEL. */
3965 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3966 && INSN_UID (jump) < max_jump_chain)
3968 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3969 jump_chain[INSN_UID (nlabel)] = jump;
3972 PATTERN (jump) = gen_jump (nlabel);
3973 JUMP_LABEL (jump) = nlabel;
3974 ++LABEL_NUSES (nlabel);
3975 INSN_CODE (jump) = -1;
3977 if (--LABEL_NUSES (olabel) == 0)
3979 delete_labelref_insn (jump, olabel, 0);
3980 delete_insn (olabel);
3984 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3985 If we found one, delete it and then delete this insn if DELETE_THIS is
3986 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3989 delete_labelref_insn (insn, label, delete_this)
3996 if (GET_CODE (insn) != NOTE
3997 && reg_mentioned_p (label, PATTERN (insn)))
4008 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4009 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4023 /* Like rtx_equal_p except that it considers two REGs as equal
4024 if they renumber to the same value and considers two commutative
4025 operations to be the same if the order of the operands has been
4029 rtx_renumbered_equal_p (x, y)
4033 register RTX_CODE code = GET_CODE (x);
4039 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4040 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4041 && GET_CODE (SUBREG_REG (y)) == REG)))
4043 int reg_x = -1, reg_y = -1;
4044 int word_x = 0, word_y = 0;
4046 if (GET_MODE (x) != GET_MODE (y))
4049 /* If we haven't done any renumbering, don't
4050 make any assumptions. */
4051 if (reg_renumber == 0)
4052 return rtx_equal_p (x, y);
4056 reg_x = REGNO (SUBREG_REG (x));
4057 word_x = SUBREG_WORD (x);
4059 if (reg_renumber[reg_x] >= 0)
4061 reg_x = reg_renumber[reg_x] + word_x;
4069 if (reg_renumber[reg_x] >= 0)
4070 reg_x = reg_renumber[reg_x];
4073 if (GET_CODE (y) == SUBREG)
4075 reg_y = REGNO (SUBREG_REG (y));
4076 word_y = SUBREG_WORD (y);
4078 if (reg_renumber[reg_y] >= 0)
4080 reg_y = reg_renumber[reg_y];
4088 if (reg_renumber[reg_y] >= 0)
4089 reg_y = reg_renumber[reg_y];
4092 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4095 /* Now we have disposed of all the cases
4096 in which different rtx codes can match. */
4097 if (code != GET_CODE (y))
4109 return INTVAL (x) == INTVAL (y);
4112 /* We can't assume nonlocal labels have their following insns yet. */
4113 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4114 return XEXP (x, 0) == XEXP (y, 0);
4116 /* Two label-refs are equivalent if they point at labels
4117 in the same position in the instruction stream. */
4118 return (next_real_insn (XEXP (x, 0))
4119 == next_real_insn (XEXP (y, 0)));
4122 return XSTR (x, 0) == XSTR (y, 0);
4125 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4127 if (GET_MODE (x) != GET_MODE (y))
4130 /* For commutative operations, the RTX match if the operand match in any
4131 order. Also handle the simple binary and unary cases without a loop. */
4132 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4133 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4134 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4135 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4136 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4137 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4138 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4139 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4140 else if (GET_RTX_CLASS (code) == '1')
4141 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4143 /* Compare the elements. If any pair of corresponding elements
4144 fail to match, return 0 for the whole things. */
4146 fmt = GET_RTX_FORMAT (code);
4147 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4153 if (XWINT (x, i) != XWINT (y, i))
4158 if (XINT (x, i) != XINT (y, i))
4163 if (strcmp (XSTR (x, i), XSTR (y, i)))
4168 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4173 if (XEXP (x, i) != XEXP (y, i))
4180 if (XVECLEN (x, i) != XVECLEN (y, i))
4182 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4183 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4194 /* If X is a hard register or equivalent to one or a subregister of one,
4195 return the hard register number. If X is a pseudo register that was not
4196 assigned a hard register, return the pseudo register number. Otherwise,
4197 return -1. Any rtx is valid for X. */
4203 if (GET_CODE (x) == REG)
4205 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4206 return reg_renumber[REGNO (x)];
4209 if (GET_CODE (x) == SUBREG)
4211 int base = true_regnum (SUBREG_REG (x));
4212 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4213 return SUBREG_WORD (x) + base;
4218 /* Optimize code of the form:
4220 for (x = a[i]; x; ...)
4222 for (x = a[i]; x; ...)
4226 Loop optimize will change the above code into
4230 { ...; if (! (x = ...)) break; }
4233 { ...; if (! (x = ...)) break; }
4236 In general, if the first test fails, the program can branch
4237 directly to `foo' and skip the second try which is doomed to fail.
4238 We run this after loop optimization and before flow analysis. */
4240 /* When comparing the insn patterns, we track the fact that different
4241 pseudo-register numbers may have been used in each computation.
4242 The following array stores an equivalence -- same_regs[I] == J means
4243 that pseudo register I was used in the first set of tests in a context
4244 where J was used in the second set. We also count the number of such
4245 pending equivalences. If nonzero, the expressions really aren't the
4248 static int *same_regs;
4250 static int num_same_regs;
4252 /* Track any registers modified between the target of the first jump and
4253 the second jump. They never compare equal. */
4255 static char *modified_regs;
4257 /* Record if memory was modified. */
4259 static int modified_mem;
4261 /* Called via note_stores on each insn between the target of the first
4262 branch and the second branch. It marks any changed registers. */
4265 mark_modified_reg (dest, x)
4271 if (GET_CODE (dest) == SUBREG)
4272 dest = SUBREG_REG (dest);
4274 if (GET_CODE (dest) == MEM)
4277 if (GET_CODE (dest) != REG)
4280 regno = REGNO (dest);
4281 if (regno >= FIRST_PSEUDO_REGISTER)
4282 modified_regs[regno] = 1;
4284 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4285 modified_regs[regno + i] = 1;
4288 /* F is the first insn in the chain of insns. */
4291 thread_jumps (f, max_reg, flag_before_loop)
4294 int flag_before_loop;
4296 /* Basic algorithm is to find a conditional branch,
4297 the label it may branch to, and the branch after
4298 that label. If the two branches test the same condition,
4299 walk back from both branch paths until the insn patterns
4300 differ, or code labels are hit. If we make it back to
4301 the target of the first branch, then we know that the first branch
4302 will either always succeed or always fail depending on the relative
4303 senses of the two branches. So adjust the first branch accordingly
4306 rtx label, b1, b2, t1, t2;
4307 enum rtx_code code1, code2;
4308 rtx b1op0, b1op1, b2op0, b2op1;
4313 /* Allocate register tables and quick-reset table. */
4314 modified_regs = (char *) alloca (max_reg * sizeof (char));
4315 same_regs = (int *) alloca (max_reg * sizeof (int));
4316 all_reset = (int *) alloca (max_reg * sizeof (int));
4317 for (i = 0; i < max_reg; i++)
4324 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4326 /* Get to a candidate branch insn. */
4327 if (GET_CODE (b1) != JUMP_INSN
4328 || ! condjump_p (b1) || simplejump_p (b1)
4329 || JUMP_LABEL (b1) == 0)
4332 bzero (modified_regs, max_reg * sizeof (char));
4335 bcopy ((char *) all_reset, (char *) same_regs,
4336 max_reg * sizeof (int));
4339 label = JUMP_LABEL (b1);
4341 /* Look for a branch after the target. Record any registers and
4342 memory modified between the target and the branch. Stop when we
4343 get to a label since we can't know what was changed there. */
4344 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4346 if (GET_CODE (b2) == CODE_LABEL)
4349 else if (GET_CODE (b2) == JUMP_INSN)
4351 /* If this is an unconditional jump and is the only use of
4352 its target label, we can follow it. */
4353 if (simplejump_p (b2)
4354 && JUMP_LABEL (b2) != 0
4355 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4357 b2 = JUMP_LABEL (b2);
4364 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4367 if (GET_CODE (b2) == CALL_INSN)
4370 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4371 if (call_used_regs[i] && ! fixed_regs[i]
4372 && i != STACK_POINTER_REGNUM
4373 && i != FRAME_POINTER_REGNUM
4374 && i != HARD_FRAME_POINTER_REGNUM
4375 && i != ARG_POINTER_REGNUM)
4376 modified_regs[i] = 1;
4379 note_stores (PATTERN (b2), mark_modified_reg);
4382 /* Check the next candidate branch insn from the label
4385 || GET_CODE (b2) != JUMP_INSN
4387 || ! condjump_p (b2)
4388 || simplejump_p (b2))
4391 /* Get the comparison codes and operands, reversing the
4392 codes if appropriate. If we don't have comparison codes,
4393 we can't do anything. */
4394 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4395 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4396 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4397 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4398 code1 = reverse_condition (code1);
4400 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4401 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4402 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4403 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4404 code2 = reverse_condition (code2);
4406 /* If they test the same things and knowing that B1 branches
4407 tells us whether or not B2 branches, check if we
4408 can thread the branch. */
4409 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4410 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4411 && (comparison_dominates_p (code1, code2)
4412 || comparison_dominates_p (code1, reverse_condition (code2))))
4414 t1 = prev_nonnote_insn (b1);
4415 t2 = prev_nonnote_insn (b2);
4417 while (t1 != 0 && t2 != 0)
4421 /* We have reached the target of the first branch.
4422 If there are no pending register equivalents,
4423 we know that this branch will either always
4424 succeed (if the senses of the two branches are
4425 the same) or always fail (if not). */
4428 if (num_same_regs != 0)
4431 if (comparison_dominates_p (code1, code2))
4432 new_label = JUMP_LABEL (b2);
4434 new_label = get_label_after (b2);
4436 if (JUMP_LABEL (b1) != new_label)
4438 rtx prev = PREV_INSN (new_label);
4440 if (flag_before_loop
4441 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4443 /* Don't thread to the loop label. If a loop
4444 label is reused, loop optimization will
4445 be disabled for that loop. */
4446 new_label = gen_label_rtx ();
4447 emit_label_after (new_label, PREV_INSN (prev));
4449 changed |= redirect_jump (b1, new_label);
4454 /* If either of these is not a normal insn (it might be
4455 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4456 have already been skipped above.) Similarly, fail
4457 if the insns are different. */
4458 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4459 || recog_memoized (t1) != recog_memoized (t2)
4460 || ! rtx_equal_for_thread_p (PATTERN (t1),
4464 t1 = prev_nonnote_insn (t1);
4465 t2 = prev_nonnote_insn (t2);
4472 /* This is like RTX_EQUAL_P except that it knows about our handling of
4473 possibly equivalent registers and knows to consider volatile and
4474 modified objects as not equal.
4476 YINSN is the insn containing Y. */
4479 rtx_equal_for_thread_p (x, y, yinsn)
4485 register enum rtx_code code;
4488 code = GET_CODE (x);
4489 /* Rtx's of different codes cannot be equal. */
4490 if (code != GET_CODE (y))
4493 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4494 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4496 if (GET_MODE (x) != GET_MODE (y))
4499 /* For commutative operations, the RTX match if the operand match in any
4500 order. Also handle the simple binary and unary cases without a loop. */
4501 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4502 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4503 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4504 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4505 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4506 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4507 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4508 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4509 else if (GET_RTX_CLASS (code) == '1')
4510 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4512 /* Handle special-cases first. */
4516 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4519 /* If neither is user variable or hard register, check for possible
4521 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4522 || REGNO (x) < FIRST_PSEUDO_REGISTER
4523 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4526 if (same_regs[REGNO (x)] == -1)
4528 same_regs[REGNO (x)] = REGNO (y);
4531 /* If this is the first time we are seeing a register on the `Y'
4532 side, see if it is the last use. If not, we can't thread the
4533 jump, so mark it as not equivalent. */
4534 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
4540 return (same_regs[REGNO (x)] == REGNO (y));
4545 /* If memory modified or either volatile, not equivalent.
4546 Else, check address. */
4547 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4550 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4553 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4559 /* Cancel a pending `same_regs' if setting equivalenced registers.
4560 Then process source. */
4561 if (GET_CODE (SET_DEST (x)) == REG
4562 && GET_CODE (SET_DEST (y)) == REG)
4564 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4566 same_regs[REGNO (SET_DEST (x))] = -1;
4569 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4573 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4576 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4579 return XEXP (x, 0) == XEXP (y, 0);
4582 return XSTR (x, 0) == XSTR (y, 0);
4588 fmt = GET_RTX_FORMAT (code);
4589 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4594 if (XWINT (x, i) != XWINT (y, i))
4600 if (XINT (x, i) != XINT (y, i))
4606 /* Two vectors must have the same length. */
4607 if (XVECLEN (x, i) != XVECLEN (y, i))
4610 /* And the corresponding elements must match. */
4611 for (j = 0; j < XVECLEN (x, i); j++)
4612 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4613 XVECEXP (y, i, j), yinsn) == 0)
4618 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4624 if (strcmp (XSTR (x, i), XSTR (y, i)))
4629 /* These are just backpointers, so they don't matter. */
4635 /* It is believed that rtx's at this level will never
4636 contain anything but integers and other rtx's,
4637 except for within LABEL_REFs and SYMBOL_REFs. */