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 INSN_CODE (insn) = -1;
480 /* Remove all reg notes but the REG_DEAD one. */
481 REG_NOTES (insn) = trial;
482 XEXP (trial, 1) = NULL_RTX;
489 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
490 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
492 GET_MODE (SET_DEST (body))))
494 /* This handles the case where we have two consecutive
495 assignments of the same constant to pseudos that didn't
496 get a hard reg. Each SET from the constant will be
497 converted into a SET of the spill register and an
498 output reload will be made following it. This produces
499 two loads of the same constant into the same spill
504 /* Look back for a death note for the first reg.
505 If there is one, it is no longer accurate. */
506 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
508 if ((GET_CODE (in_insn) == INSN
509 || GET_CODE (in_insn) == JUMP_INSN)
510 && find_regno_note (in_insn, REG_DEAD, dreg))
512 remove_death (dreg, in_insn);
515 in_insn = PREV_INSN (in_insn);
518 /* Delete the second load of the value. */
522 else if (GET_CODE (body) == PARALLEL)
524 /* If each part is a set between two identical registers or
525 a USE or CLOBBER, delete the insn. */
529 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
531 tem = XVECEXP (body, 0, i);
532 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
535 if (GET_CODE (tem) != SET
536 || (sreg = true_regnum (SET_SRC (tem))) < 0
537 || (dreg = true_regnum (SET_DEST (tem))) < 0
545 /* Also delete insns to store bit fields if they are no-ops. */
546 /* Not worth the hair to detect this in the big-endian case. */
547 else if (! BYTES_BIG_ENDIAN
548 && GET_CODE (body) == SET
549 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
550 && XEXP (SET_DEST (body), 2) == const0_rtx
551 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
552 && ! (GET_CODE (SET_SRC (body)) == MEM
553 && MEM_VOLATILE_P (SET_SRC (body))))
559 /* If we haven't yet gotten to reload and we have just run regscan,
560 delete any insn that sets a register that isn't used elsewhere.
561 This helps some of the optimizations below by having less insns
562 being jumped around. */
564 if (! reload_completed && after_regscan)
565 for (insn = f; insn; insn = next)
567 rtx set = single_set (insn);
569 next = NEXT_INSN (insn);
571 if (set && GET_CODE (SET_DEST (set)) == REG
572 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
573 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
574 /* We use regno_last_note_uid so as not to delete the setting
575 of a reg that's used in notes. A subsequent optimization
576 might arrange to use that reg for real. */
577 && regno_last_note_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
578 && ! side_effects_p (SET_SRC (set))
579 && ! find_reg_note (insn, REG_RETVAL, 0))
583 /* Now iterate optimizing jumps until nothing changes over one pass. */
589 for (insn = f; insn; insn = next)
592 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
594 int this_is_simplejump, this_is_condjump, reversep;
595 int this_is_condjump_in_parallel;
597 /* If NOT the first iteration, if this is the last jump pass
598 (just before final), do the special peephole optimizations.
599 Avoiding the first iteration gives ordinary jump opts
600 a chance to work before peephole opts. */
602 if (reload_completed && !first && !flag_no_peephole)
603 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
607 /* That could have deleted some insns after INSN, so check now
608 what the following insn is. */
610 next = NEXT_INSN (insn);
612 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
613 jump. Try to optimize by duplicating the loop exit test if so.
614 This is only safe immediately after regscan, because it uses
615 the values of regno_first_uid and regno_last_uid. */
616 if (after_regscan && GET_CODE (insn) == NOTE
617 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
618 && (temp1 = next_nonnote_insn (insn)) != 0
619 && simplejump_p (temp1))
621 temp = PREV_INSN (insn);
622 if (duplicate_loop_exit_test (insn))
625 next = NEXT_INSN (temp);
630 if (GET_CODE (insn) != JUMP_INSN)
633 this_is_simplejump = simplejump_p (insn);
634 this_is_condjump = condjump_p (insn);
635 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
637 /* Tension the labels in dispatch tables. */
639 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
640 changed |= tension_vector_labels (PATTERN (insn), 0);
641 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
642 changed |= tension_vector_labels (PATTERN (insn), 1);
644 /* If a dispatch table always goes to the same place,
645 get rid of it and replace the insn that uses it. */
647 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
648 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
651 rtx pat = PATTERN (insn);
652 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
653 int len = XVECLEN (pat, diff_vec_p);
654 rtx dispatch = prev_real_insn (insn);
656 for (i = 0; i < len; i++)
657 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
658 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
662 && GET_CODE (dispatch) == JUMP_INSN
663 && JUMP_LABEL (dispatch) != 0
664 /* Don't mess with a casesi insn. */
665 && !(GET_CODE (PATTERN (dispatch)) == SET
666 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
668 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
670 redirect_tablejump (dispatch,
671 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
676 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
678 /* If a jump references the end of the function, try to turn
679 it into a RETURN insn, possibly a conditional one. */
680 if (JUMP_LABEL (insn)
681 && (next_active_insn (JUMP_LABEL (insn)) == 0
682 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
684 changed |= redirect_jump (insn, NULL_RTX);
686 /* Detect jump to following insn. */
687 if (reallabelprev == insn && condjump_p (insn))
689 next = next_real_insn (JUMP_LABEL (insn));
695 /* If we have an unconditional jump preceded by a USE, try to put
696 the USE before the target and jump there. This simplifies many
697 of the optimizations below since we don't have to worry about
698 dealing with these USE insns. We only do this if the label
699 being branch to already has the identical USE or if code
700 never falls through to that label. */
702 if (this_is_simplejump
703 && (temp = prev_nonnote_insn (insn)) != 0
704 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
705 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
706 && (GET_CODE (temp1) == BARRIER
707 || (GET_CODE (temp1) == INSN
708 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
709 /* Don't do this optimization if we have a loop containing only
710 the USE instruction, and the loop start label has a usage
711 count of 1. This is because we will redo this optimization
712 everytime through the outer loop, and jump opt will never
714 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
715 && temp2 == JUMP_LABEL (insn)
716 && LABEL_NUSES (temp2) == 1))
718 if (GET_CODE (temp1) == BARRIER)
720 emit_insn_after (PATTERN (temp), temp1);
721 temp1 = NEXT_INSN (temp1);
725 redirect_jump (insn, get_label_before (temp1));
726 reallabelprev = prev_real_insn (temp1);
730 /* Simplify if (...) x = a; else x = b; by converting it
731 to x = b; if (...) x = a;
732 if B is sufficiently simple, the test doesn't involve X,
733 and nothing in the test modifies B or X.
735 If we have small register classes, we also can't do this if X
738 If the "x = b;" insn has any REG_NOTES, we don't do this because
739 of the possibility that we are running after CSE and there is a
740 REG_EQUAL note that is only valid if the branch has already been
741 taken. If we move the insn with the REG_EQUAL note, we may
742 fold the comparison to always be false in a later CSE pass.
743 (We could also delete the REG_NOTES when moving the insn, but it
744 seems simpler to not move it.) An exception is that we can move
745 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
746 value is the same as "b".
748 INSN is the branch over the `else' part.
752 TEMP to the jump insn preceding "x = a;"
754 TEMP2 to the insn that sets "x = b;"
755 TEMP3 to the insn that sets "x = a;"
756 TEMP4 to the set of "x = b"; */
758 if (this_is_simplejump
759 && (temp3 = prev_active_insn (insn)) != 0
760 && GET_CODE (temp3) == INSN
761 && (temp4 = single_set (temp3)) != 0
762 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
763 #ifdef SMALL_REGISTER_CLASSES
764 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
766 && (temp2 = next_active_insn (insn)) != 0
767 && GET_CODE (temp2) == INSN
768 && (temp4 = single_set (temp2)) != 0
769 && rtx_equal_p (SET_DEST (temp4), temp1)
770 && (GET_CODE (SET_SRC (temp4)) == REG
771 || GET_CODE (SET_SRC (temp4)) == SUBREG
772 || CONSTANT_P (SET_SRC (temp4)))
773 && (REG_NOTES (temp2) == 0
774 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
775 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
776 && XEXP (REG_NOTES (temp2), 1) == 0
777 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
779 && (temp = prev_active_insn (temp3)) != 0
780 && condjump_p (temp) && ! simplejump_p (temp)
781 /* TEMP must skip over the "x = a;" insn */
782 && prev_real_insn (JUMP_LABEL (temp)) == insn
783 && no_labels_between_p (insn, JUMP_LABEL (temp))
784 /* There must be no other entries to the "x = b;" insn. */
785 && no_labels_between_p (JUMP_LABEL (temp), temp2)
786 /* INSN must either branch to the insn after TEMP2 or the insn
787 after TEMP2 must branch to the same place as INSN. */
788 && (reallabelprev == temp2
789 || ((temp5 = next_active_insn (temp2)) != 0
790 && simplejump_p (temp5)
791 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
793 /* The test expression, X, may be a complicated test with
794 multiple branches. See if we can find all the uses of
795 the label that TEMP branches to without hitting a CALL_INSN
796 or a jump to somewhere else. */
797 rtx target = JUMP_LABEL (temp);
798 int nuses = LABEL_NUSES (target);
801 /* Set P to the first jump insn that goes around "x = a;". */
802 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
804 if (GET_CODE (p) == JUMP_INSN)
806 if (condjump_p (p) && ! simplejump_p (p)
807 && JUMP_LABEL (p) == target)
816 else if (GET_CODE (p) == CALL_INSN)
821 /* We cannot insert anything between a set of cc and its use
822 so if P uses cc0, we must back up to the previous insn. */
823 q = prev_nonnote_insn (p);
824 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
825 && sets_cc0_p (PATTERN (q)))
832 /* If we found all the uses and there was no data conflict, we
833 can move the assignment unless we can branch into the middle
836 && no_labels_between_p (p, insn)
837 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
838 && ! reg_set_between_p (temp1, p, temp3)
839 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
840 || ! reg_set_between_p (SET_SRC (temp4), p, temp2)))
842 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
845 /* Set NEXT to an insn that we know won't go away. */
846 next = next_active_insn (insn);
848 /* Delete the jump around the set. Note that we must do
849 this before we redirect the test jumps so that it won't
850 delete the code immediately following the assignment
851 we moved (which might be a jump). */
855 /* We either have two consecutive labels or a jump to
856 a jump, so adjust all the JUMP_INSNs to branch to where
858 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
859 if (GET_CODE (p) == JUMP_INSN)
860 redirect_jump (p, target);
867 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
868 to x = a; if (...) goto l; x = b;
869 if A is sufficiently simple, the test doesn't involve X,
870 and nothing in the test modifies A or X.
872 If we have small register classes, we also can't do this if X
875 If the "x = a;" insn has any REG_NOTES, we don't do this because
876 of the possibility that we are running after CSE and there is a
877 REG_EQUAL note that is only valid if the branch has already been
878 taken. If we move the insn with the REG_EQUAL note, we may
879 fold the comparison to always be false in a later CSE pass.
880 (We could also delete the REG_NOTES when moving the insn, but it
881 seems simpler to not move it.) An exception is that we can move
882 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
883 value is the same as "a".
889 TEMP to the jump insn preceding "x = a;"
891 TEMP2 to the insn that sets "x = b;"
892 TEMP3 to the insn that sets "x = a;"
893 TEMP4 to the set of "x = a"; */
895 if (this_is_simplejump
896 && (temp2 = next_active_insn (insn)) != 0
897 && GET_CODE (temp2) == INSN
898 && (temp4 = single_set (temp2)) != 0
899 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
900 #ifdef SMALL_REGISTER_CLASSES
901 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
904 && (temp3 = prev_active_insn (insn)) != 0
905 && GET_CODE (temp3) == INSN
906 && (temp4 = single_set (temp3)) != 0
907 && rtx_equal_p (SET_DEST (temp4), temp1)
908 && (GET_CODE (SET_SRC (temp4)) == REG
909 || GET_CODE (SET_SRC (temp4)) == SUBREG
910 || CONSTANT_P (SET_SRC (temp4)))
911 && (REG_NOTES (temp3) == 0
912 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
913 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
914 && XEXP (REG_NOTES (temp3), 1) == 0
915 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
917 && (temp = prev_active_insn (temp3)) != 0
918 && condjump_p (temp) && ! simplejump_p (temp)
919 /* TEMP must skip over the "x = a;" insn */
920 && prev_real_insn (JUMP_LABEL (temp)) == insn
921 && no_labels_between_p (temp, insn))
923 rtx prev_label = JUMP_LABEL (temp);
924 rtx insert_after = prev_nonnote_insn (temp);
927 /* We cannot insert anything between a set of cc and its use. */
928 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
929 && sets_cc0_p (PATTERN (insert_after)))
930 insert_after = prev_nonnote_insn (insert_after);
932 ++LABEL_NUSES (prev_label);
935 && no_labels_between_p (insert_after, temp)
936 && ! reg_referenced_between_p (temp1, insert_after, temp3)
937 && ! reg_referenced_between_p (temp1, temp3,
939 && ! reg_set_between_p (temp1, insert_after, temp)
940 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
941 || ! reg_set_between_p (SET_SRC (temp4),
943 && invert_jump (temp, JUMP_LABEL (insn)))
945 emit_insn_after_with_line_notes (PATTERN (temp3),
946 insert_after, temp3);
949 /* Set NEXT to an insn that we know won't go away. */
953 if (prev_label && --LABEL_NUSES (prev_label) == 0)
954 delete_insn (prev_label);
960 /* If we have if (...) x = exp; and branches are expensive,
961 EXP is a single insn, does not have any side effects, cannot
962 trap, and is not too costly, convert this to
963 t = exp; if (...) x = t;
965 Don't do this when we have CC0 because it is unlikely to help
966 and we'd need to worry about where to place the new insn and
967 the potential for conflicts. We also can't do this when we have
968 notes on the insn for the same reason as above.
972 TEMP to the "x = exp;" insn.
973 TEMP1 to the single set in the "x = exp; insn.
976 if (! reload_completed
977 && this_is_condjump && ! this_is_simplejump
979 && (temp = next_nonnote_insn (insn)) != 0
980 && GET_CODE (temp) == INSN
981 && REG_NOTES (temp) == 0
982 && (reallabelprev == temp
983 || ((temp2 = next_active_insn (temp)) != 0
984 && simplejump_p (temp2)
985 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
986 && (temp1 = single_set (temp)) != 0
987 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
988 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
989 #ifdef SMALL_REGISTER_CLASSES
990 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
992 && GET_CODE (SET_SRC (temp1)) != REG
993 && GET_CODE (SET_SRC (temp1)) != SUBREG
994 && GET_CODE (SET_SRC (temp1)) != CONST_INT
995 && ! side_effects_p (SET_SRC (temp1))
996 && ! may_trap_p (SET_SRC (temp1))
997 && rtx_cost (SET_SRC (temp1), SET) < 10)
999 rtx new = gen_reg_rtx (GET_MODE (temp2));
1001 if (validate_change (temp, &SET_DEST (temp1), new, 0))
1003 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1004 emit_insn_after_with_line_notes (PATTERN (temp),
1005 PREV_INSN (insn), temp);
1007 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1011 /* Similarly, if it takes two insns to compute EXP but they
1012 have the same destination. Here TEMP3 will be the second
1013 insn and TEMP4 the SET from that insn. */
1015 if (! reload_completed
1016 && this_is_condjump && ! this_is_simplejump
1018 && (temp = next_nonnote_insn (insn)) != 0
1019 && GET_CODE (temp) == INSN
1020 && REG_NOTES (temp) == 0
1021 && (temp3 = next_nonnote_insn (temp)) != 0
1022 && GET_CODE (temp3) == INSN
1023 && REG_NOTES (temp3) == 0
1024 && (reallabelprev == temp3
1025 || ((temp2 = next_active_insn (temp3)) != 0
1026 && simplejump_p (temp2)
1027 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1028 && (temp1 = single_set (temp)) != 0
1029 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
1030 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1031 #ifdef SMALL_REGISTER_CLASSES
1032 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
1034 && ! side_effects_p (SET_SRC (temp1))
1035 && ! may_trap_p (SET_SRC (temp1))
1036 && rtx_cost (SET_SRC (temp1), SET) < 10
1037 && (temp4 = single_set (temp3)) != 0
1038 && rtx_equal_p (SET_DEST (temp4), temp2)
1039 && ! side_effects_p (SET_SRC (temp4))
1040 && ! may_trap_p (SET_SRC (temp4))
1041 && rtx_cost (SET_SRC (temp4), SET) < 10)
1043 rtx new = gen_reg_rtx (GET_MODE (temp2));
1045 if (validate_change (temp, &SET_DEST (temp1), new, 0))
1047 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1048 emit_insn_after_with_line_notes (PATTERN (temp),
1049 PREV_INSN (insn), temp);
1050 emit_insn_after_with_line_notes
1051 (replace_rtx (PATTERN (temp3), temp2, new),
1052 PREV_INSN (insn), temp3);
1054 delete_insn (temp3);
1055 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1059 /* Finally, handle the case where two insns are used to
1060 compute EXP but a temporary register is used. Here we must
1061 ensure that the temporary register is not used anywhere else. */
1063 if (! reload_completed
1065 && this_is_condjump && ! this_is_simplejump
1067 && (temp = next_nonnote_insn (insn)) != 0
1068 && GET_CODE (temp) == INSN
1069 && REG_NOTES (temp) == 0
1070 && (temp3 = next_nonnote_insn (temp)) != 0
1071 && GET_CODE (temp3) == INSN
1072 && REG_NOTES (temp3) == 0
1073 && (reallabelprev == temp3
1074 || ((temp2 = next_active_insn (temp3)) != 0
1075 && simplejump_p (temp2)
1076 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1077 && (temp1 = single_set (temp)) != 0
1078 && (temp5 = SET_DEST (temp1),
1079 (GET_CODE (temp5) == REG
1080 || (GET_CODE (temp5) == SUBREG
1081 && (temp5 = SUBREG_REG (temp5),
1082 GET_CODE (temp5) == REG))))
1083 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
1084 && regno_first_uid[REGNO (temp5)] == INSN_UID (temp)
1085 && regno_last_uid[REGNO (temp5)] == INSN_UID (temp3)
1086 && ! side_effects_p (SET_SRC (temp1))
1087 && ! may_trap_p (SET_SRC (temp1))
1088 && rtx_cost (SET_SRC (temp1), SET) < 10
1089 && (temp4 = single_set (temp3)) != 0
1090 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
1091 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1092 #ifdef SMALL_REGISTER_CLASSES
1093 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
1095 && rtx_equal_p (SET_DEST (temp4), temp2)
1096 && ! side_effects_p (SET_SRC (temp4))
1097 && ! may_trap_p (SET_SRC (temp4))
1098 && rtx_cost (SET_SRC (temp4), SET) < 10)
1100 rtx new = gen_reg_rtx (GET_MODE (temp2));
1102 if (validate_change (temp3, &SET_DEST (temp4), new, 0))
1104 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1105 emit_insn_after_with_line_notes (PATTERN (temp),
1106 PREV_INSN (insn), temp);
1107 emit_insn_after_with_line_notes (PATTERN (temp3),
1108 PREV_INSN (insn), temp3);
1110 delete_insn (temp3);
1111 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1114 #endif /* HAVE_cc0 */
1116 /* Try to use a conditional move (if the target has them), or a
1117 store-flag insn. The general case is:
1119 1) x = a; if (...) x = b; and
1122 If the jump would be faster, the machine should not have defined
1123 the movcc or scc insns!. These cases are often made by the
1124 previous optimization.
1126 The second case is treated as x = x; if (...) x = b;.
1128 INSN here is the jump around the store. We set:
1130 TEMP to the "x = b;" insn.
1133 TEMP3 to A (X in the second case).
1134 TEMP4 to the condition being tested.
1135 TEMP5 to the earliest insn used to find the condition. */
1137 if (/* We can't do this after reload has completed. */
1139 && this_is_condjump && ! this_is_simplejump
1140 /* Set TEMP to the "x = b;" insn. */
1141 && (temp = next_nonnote_insn (insn)) != 0
1142 && GET_CODE (temp) == INSN
1143 && GET_CODE (PATTERN (temp)) == SET
1144 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1145 #ifdef SMALL_REGISTER_CLASSES
1146 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
1148 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1149 || GET_CODE (temp2) == SUBREG
1150 /* ??? How about floating point constants? */
1151 || GET_CODE (temp2) == CONST_INT)
1152 /* Allow either form, but prefer the former if both apply.
1153 There is no point in using the old value of TEMP1 if
1154 it is a register, since cse will alias them. It can
1155 lose if the old value were a hard register since CSE
1156 won't replace hard registers. */
1157 && (((temp3 = reg_set_last (temp1, insn)) != 0)
1158 /* Make the latter case look like x = x; if (...) x = b; */
1159 || (temp3 = temp1, 1))
1160 /* INSN must either branch to the insn after TEMP or the insn
1161 after TEMP must branch to the same place as INSN. */
1162 && (reallabelprev == temp
1163 || ((temp4 = next_active_insn (temp)) != 0
1164 && simplejump_p (temp4)
1165 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1166 && (temp4 = get_condition (insn, &temp5)) != 0
1167 /* We must be comparing objects whose modes imply the size.
1168 We could handle BLKmode if (1) emit_store_flag could
1169 and (2) we could find the size reliably. */
1170 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1171 /* Even if branches are cheap, the store_flag optimization
1172 can win when the operation to be performed can be
1173 expressed directly. */
1175 /* If the previous insn sets CC0 and something else, we can't
1176 do this since we are going to delete that insn. */
1178 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1179 && GET_CODE (temp6) == INSN
1180 && (sets_cc0_p (PATTERN (temp6)) == -1
1181 || (sets_cc0_p (PATTERN (temp6)) == 1
1182 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1186 #ifdef HAVE_conditional_move
1187 /* First try a conditional move. */
1189 enum rtx_code code = GET_CODE (temp4);
1191 rtx cond0, cond1, aval, bval;
1194 /* Copy the compared variables into cond0 and cond1, so that
1195 any side effects performed in or after the old comparison,
1196 will not affect our compare which will come later. */
1197 /* ??? Is it possible to just use the comparison in the jump
1198 insn? After all, we're going to delete it. We'd have
1199 to modify emit_conditional_move to take a comparison rtx
1200 instead or write a new function. */
1201 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1202 /* We want the target to be able to simplify comparisons with
1203 zero (and maybe other constants as well), so don't create
1204 pseudos for them. There's no need to either. */
1205 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1206 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1207 cond1 = XEXP (temp4, 1);
1209 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1215 target = emit_conditional_move (var, code,
1216 cond0, cond1, VOIDmode,
1217 aval, bval, GET_MODE (var),
1218 (code == LTU || code == GEU
1219 || code == LEU || code == GTU));
1225 /* Save the conditional move sequence but don't emit it
1226 yet. On some machines, like the alpha, it is possible
1227 that temp5 == insn, so next generate the sequence that
1228 saves the compared values and then emit both
1229 sequences ensuring seq1 occurs before seq2. */
1230 seq2 = get_insns ();
1233 /* Now that we can't fail, generate the copy insns that
1234 preserve the compared values. */
1236 emit_move_insn (cond0, XEXP (temp4, 0));
1237 if (cond1 != XEXP (temp4, 1))
1238 emit_move_insn (cond1, XEXP (temp4, 1));
1239 seq1 = get_insns ();
1242 emit_insns_before (seq1, temp5);
1243 /* Insert conditional move after insn, to be sure that
1244 the jump and a possible compare won't be separated */
1245 emit_insns_after (seq2, insn);
1247 /* ??? We can also delete the insn that sets X to A.
1248 Flow will do it too though. */
1250 next = NEXT_INSN (insn);
1260 /* That didn't work, try a store-flag insn.
1262 We further divide the cases into:
1264 1) x = a; if (...) x = b; and either A or B is zero,
1265 2) if (...) x = 0; and jumps are expensive,
1266 3) x = a; if (...) x = b; and A and B are constants where all
1267 the set bits in A are also set in B and jumps are expensive,
1268 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1270 5) if (...) x = b; if jumps are even more expensive. */
1272 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1273 && ((GET_CODE (temp3) == CONST_INT)
1274 /* Make the latter case look like
1275 x = x; if (...) x = 0; */
1278 && temp2 == const0_rtx)
1279 || BRANCH_COST >= 3)))
1280 /* If B is zero, OK; if A is zero, can only do (1) if we
1281 can reverse the condition. See if (3) applies possibly
1282 by reversing the condition. Prefer reversing to (4) when
1283 branches are very expensive. */
1284 && (((BRANCH_COST >= 2
1285 || STORE_FLAG_VALUE == -1
1286 || (STORE_FLAG_VALUE == 1
1287 /* Check that the mask is a power of two,
1288 so that it can probably be generated
1290 && exact_log2 (INTVAL (temp3)) >= 0))
1291 && (reversep = 0, temp2 == const0_rtx))
1292 || ((BRANCH_COST >= 2
1293 || STORE_FLAG_VALUE == -1
1294 || (STORE_FLAG_VALUE == 1
1295 && exact_log2 (INTVAL (temp2)) >= 0))
1296 && temp3 == const0_rtx
1297 && (reversep = can_reverse_comparison_p (temp4, insn)))
1298 || (BRANCH_COST >= 2
1299 && GET_CODE (temp2) == CONST_INT
1300 && GET_CODE (temp3) == CONST_INT
1301 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1302 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1303 && (reversep = can_reverse_comparison_p (temp4,
1305 || BRANCH_COST >= 3)
1308 enum rtx_code code = GET_CODE (temp4);
1309 rtx uval, cval, var = temp1;
1313 /* If necessary, reverse the condition. */
1315 code = reverse_condition (code), uval = temp2, cval = temp3;
1317 uval = temp3, cval = temp2;
1319 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1320 is the constant 1, it is best to just compute the result
1321 directly. If UVAL is constant and STORE_FLAG_VALUE
1322 includes all of its bits, it is best to compute the flag
1323 value unnormalized and `and' it with UVAL. Otherwise,
1324 normalize to -1 and `and' with UVAL. */
1325 normalizep = (cval != const0_rtx ? -1
1326 : (uval == const1_rtx ? 1
1327 : (GET_CODE (uval) == CONST_INT
1328 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1331 /* We will be putting the store-flag insn immediately in
1332 front of the comparison that was originally being done,
1333 so we know all the variables in TEMP4 will be valid.
1334 However, this might be in front of the assignment of
1335 A to VAR. If it is, it would clobber the store-flag
1336 we will be emitting.
1338 Therefore, emit into a temporary which will be copied to
1339 VAR immediately after TEMP. */
1342 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1343 XEXP (temp4, 0), XEXP (temp4, 1),
1345 (code == LTU || code == LEU
1346 || code == GEU || code == GTU),
1356 /* Put the store-flag insns in front of the first insn
1357 used to compute the condition to ensure that we
1358 use the same values of them as the current
1359 comparison. However, the remainder of the insns we
1360 generate will be placed directly in front of the
1361 jump insn, in case any of the pseudos we use
1362 are modified earlier. */
1364 emit_insns_before (seq, temp5);
1368 /* Both CVAL and UVAL are non-zero. */
1369 if (cval != const0_rtx && uval != const0_rtx)
1373 tem1 = expand_and (uval, target, NULL_RTX);
1374 if (GET_CODE (cval) == CONST_INT
1375 && GET_CODE (uval) == CONST_INT
1376 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1380 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1381 target, NULL_RTX, 0);
1382 tem2 = expand_and (cval, tem2,
1383 (GET_CODE (tem2) == REG
1387 /* If we usually make new pseudos, do so here. This
1388 turns out to help machines that have conditional
1390 /* ??? Conditional moves have already been handled.
1391 This may be obsolete. */
1393 if (flag_expensive_optimizations)
1396 target = expand_binop (GET_MODE (var), ior_optab,
1400 else if (normalizep != 1)
1402 /* We know that either CVAL or UVAL is zero. If
1403 UVAL is zero, negate TARGET and `and' with CVAL.
1404 Otherwise, `and' with UVAL. */
1405 if (uval == const0_rtx)
1407 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1408 target, NULL_RTX, 0);
1412 target = expand_and (uval, target,
1413 (GET_CODE (target) == REG
1414 && ! preserve_subexpressions_p ()
1415 ? target : NULL_RTX));
1418 emit_move_insn (var, target);
1422 /* If INSN uses CC0, we must not separate it from the
1423 insn that sets cc0. */
1424 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1425 before = prev_nonnote_insn (before);
1427 emit_insns_before (seq, before);
1430 next = NEXT_INSN (insn);
1440 /* If branches are expensive, convert
1441 if (foo) bar++; to bar += (foo != 0);
1442 and similarly for "bar--;"
1444 INSN is the conditional branch around the arithmetic. We set:
1446 TEMP is the arithmetic insn.
1447 TEMP1 is the SET doing the arithmetic.
1448 TEMP2 is the operand being incremented or decremented.
1449 TEMP3 to the condition being tested.
1450 TEMP4 to the earliest insn used to find the condition. */
1452 if ((BRANCH_COST >= 2
1460 && ! reload_completed
1461 && this_is_condjump && ! this_is_simplejump
1462 && (temp = next_nonnote_insn (insn)) != 0
1463 && (temp1 = single_set (temp)) != 0
1464 && (temp2 = SET_DEST (temp1),
1465 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1466 && GET_CODE (SET_SRC (temp1)) == PLUS
1467 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1468 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1469 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1470 && ! side_effects_p (temp2)
1471 && ! may_trap_p (temp2)
1472 /* INSN must either branch to the insn after TEMP or the insn
1473 after TEMP must branch to the same place as INSN. */
1474 && (reallabelprev == temp
1475 || ((temp3 = next_active_insn (temp)) != 0
1476 && simplejump_p (temp3)
1477 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1478 && (temp3 = get_condition (insn, &temp4)) != 0
1479 /* We must be comparing objects whose modes imply the size.
1480 We could handle BLKmode if (1) emit_store_flag could
1481 and (2) we could find the size reliably. */
1482 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1483 && can_reverse_comparison_p (temp3, insn))
1485 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1486 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1490 /* It must be the case that TEMP2 is not modified in the range
1491 [TEMP4, INSN). The one exception we make is if the insn
1492 before INSN sets TEMP2 to something which is also unchanged
1493 in that range. In that case, we can move the initialization
1494 into our sequence. */
1496 if ((temp5 = prev_active_insn (insn)) != 0
1497 && no_labels_between_p (temp5, insn)
1498 && GET_CODE (temp5) == INSN
1499 && (temp6 = single_set (temp5)) != 0
1500 && rtx_equal_p (temp2, SET_DEST (temp6))
1501 && (CONSTANT_P (SET_SRC (temp6))
1502 || GET_CODE (SET_SRC (temp6)) == REG
1503 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1505 emit_insn (PATTERN (temp5));
1507 init = SET_SRC (temp6);
1510 if (CONSTANT_P (init)
1511 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1512 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1513 XEXP (temp3, 0), XEXP (temp3, 1),
1515 (code == LTU || code == LEU
1516 || code == GTU || code == GEU), 1);
1518 /* If we can do the store-flag, do the addition or
1522 target = expand_binop (GET_MODE (temp2),
1523 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1524 ? add_optab : sub_optab),
1525 temp2, target, temp2, 0, OPTAB_WIDEN);
1529 /* Put the result back in temp2 in case it isn't already.
1530 Then replace the jump, possible a CC0-setting insn in
1531 front of the jump, and TEMP, with the sequence we have
1534 if (target != temp2)
1535 emit_move_insn (temp2, target);
1540 emit_insns_before (seq, temp4);
1544 delete_insn (init_insn);
1546 next = NEXT_INSN (insn);
1548 delete_insn (prev_nonnote_insn (insn));
1558 /* Simplify if (...) x = 1; else {...} if (x) ...
1559 We recognize this case scanning backwards as well.
1561 TEMP is the assignment to x;
1562 TEMP1 is the label at the head of the second if. */
1563 /* ?? This should call get_condition to find the values being
1564 compared, instead of looking for a COMPARE insn when HAVE_cc0
1565 is not defined. This would allow it to work on the m88k. */
1566 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1567 is not defined and the condition is tested by a separate compare
1568 insn. This is because the code below assumes that the result
1569 of the compare dies in the following branch.
1571 Not only that, but there might be other insns between the
1572 compare and branch whose results are live. Those insns need
1575 A way to fix this is to move the insns at JUMP_LABEL (insn)
1576 to before INSN. If we are running before flow, they will
1577 be deleted if they aren't needed. But this doesn't work
1580 This is really a special-case of jump threading, anyway. The
1581 right thing to do is to replace this and jump threading with
1582 much simpler code in cse.
1584 This code has been turned off in the non-cc0 case in the
1588 else if (this_is_simplejump
1589 /* Safe to skip USE and CLOBBER insns here
1590 since they will not be deleted. */
1591 && (temp = prev_active_insn (insn))
1592 && no_labels_between_p (temp, insn)
1593 && GET_CODE (temp) == INSN
1594 && GET_CODE (PATTERN (temp)) == SET
1595 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1596 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1597 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1598 /* If we find that the next value tested is `x'
1599 (TEMP1 is the insn where this happens), win. */
1600 && GET_CODE (temp1) == INSN
1601 && GET_CODE (PATTERN (temp1)) == SET
1603 /* Does temp1 `tst' the value of x? */
1604 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1605 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1606 && (temp1 = next_nonnote_insn (temp1))
1608 /* Does temp1 compare the value of x against zero? */
1609 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1610 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1611 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1612 == SET_DEST (PATTERN (temp)))
1613 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1614 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1616 && condjump_p (temp1))
1618 /* Get the if_then_else from the condjump. */
1619 rtx choice = SET_SRC (PATTERN (temp1));
1620 if (GET_CODE (choice) == IF_THEN_ELSE)
1622 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1623 rtx val = SET_SRC (PATTERN (temp));
1625 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1629 if (cond == const_true_rtx)
1630 ultimate = XEXP (choice, 1);
1631 else if (cond == const0_rtx)
1632 ultimate = XEXP (choice, 2);
1636 if (ultimate == pc_rtx)
1637 ultimate = get_label_after (temp1);
1638 else if (ultimate && GET_CODE (ultimate) != RETURN)
1639 ultimate = XEXP (ultimate, 0);
1641 if (ultimate && JUMP_LABEL(insn) != ultimate)
1642 changed |= redirect_jump (insn, ultimate);
1648 /* @@ This needs a bit of work before it will be right.
1650 Any type of comparison can be accepted for the first and
1651 second compare. When rewriting the first jump, we must
1652 compute the what conditions can reach label3, and use the
1653 appropriate code. We can not simply reverse/swap the code
1654 of the first jump. In some cases, the second jump must be
1658 < == converts to > ==
1659 < != converts to == >
1662 If the code is written to only accept an '==' test for the second
1663 compare, then all that needs to be done is to swap the condition
1664 of the first branch.
1666 It is questionable whether we want this optimization anyways,
1667 since if the user wrote code like this because he/she knew that
1668 the jump to label1 is taken most of the time, then rewriting
1669 this gives slower code. */
1670 /* @@ This should call get_condition to find the values being
1671 compared, instead of looking for a COMPARE insn when HAVE_cc0
1672 is not defined. This would allow it to work on the m88k. */
1673 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1674 is not defined and the condition is tested by a separate compare
1675 insn. This is because the code below assumes that the result
1676 of the compare dies in the following branch. */
1678 /* Simplify test a ~= b
1692 where ~= is an inequality, e.g. >, and ~~= is the swapped
1695 We recognize this case scanning backwards.
1697 TEMP is the conditional jump to `label2';
1698 TEMP1 is the test for `a == b';
1699 TEMP2 is the conditional jump to `label1';
1700 TEMP3 is the test for `a ~= b'. */
1701 else if (this_is_simplejump
1702 && (temp = prev_active_insn (insn))
1703 && no_labels_between_p (temp, insn)
1704 && condjump_p (temp)
1705 && (temp1 = prev_active_insn (temp))
1706 && no_labels_between_p (temp1, temp)
1707 && GET_CODE (temp1) == INSN
1708 && GET_CODE (PATTERN (temp1)) == SET
1710 && sets_cc0_p (PATTERN (temp1)) == 1
1712 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1713 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1714 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1716 && (temp2 = prev_active_insn (temp1))
1717 && no_labels_between_p (temp2, temp1)
1718 && condjump_p (temp2)
1719 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1720 && (temp3 = prev_active_insn (temp2))
1721 && no_labels_between_p (temp3, temp2)
1722 && GET_CODE (PATTERN (temp3)) == SET
1723 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1724 SET_DEST (PATTERN (temp1)))
1725 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1726 SET_SRC (PATTERN (temp3)))
1727 && ! inequality_comparisons_p (PATTERN (temp))
1728 && inequality_comparisons_p (PATTERN (temp2)))
1730 rtx fallthrough_label = JUMP_LABEL (temp2);
1732 ++LABEL_NUSES (fallthrough_label);
1733 if (swap_jump (temp2, JUMP_LABEL (insn)))
1739 if (--LABEL_NUSES (fallthrough_label) == 0)
1740 delete_insn (fallthrough_label);
1743 /* Simplify if (...) {... x = 1;} if (x) ...
1745 We recognize this case backwards.
1747 TEMP is the test of `x';
1748 TEMP1 is the assignment to `x' at the end of the
1749 previous statement. */
1750 /* @@ This should call get_condition to find the values being
1751 compared, instead of looking for a COMPARE insn when HAVE_cc0
1752 is not defined. This would allow it to work on the m88k. */
1753 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1754 is not defined and the condition is tested by a separate compare
1755 insn. This is because the code below assumes that the result
1756 of the compare dies in the following branch. */
1758 /* ??? This has to be turned off. The problem is that the
1759 unconditional jump might indirectly end up branching to the
1760 label between TEMP1 and TEMP. We can't detect this, in general,
1761 since it may become a jump to there after further optimizations.
1762 If that jump is done, it will be deleted, so we will retry
1763 this optimization in the next pass, thus an infinite loop.
1765 The present code prevents this by putting the jump after the
1766 label, but this is not logically correct. */
1768 else if (this_is_condjump
1769 /* Safe to skip USE and CLOBBER insns here
1770 since they will not be deleted. */
1771 && (temp = prev_active_insn (insn))
1772 && no_labels_between_p (temp, insn)
1773 && GET_CODE (temp) == INSN
1774 && GET_CODE (PATTERN (temp)) == SET
1776 && sets_cc0_p (PATTERN (temp)) == 1
1777 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1779 /* Temp must be a compare insn, we can not accept a register
1780 to register move here, since it may not be simply a
1782 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1783 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1784 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1785 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1786 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1788 /* May skip USE or CLOBBER insns here
1789 for checking for opportunity, since we
1790 take care of them later. */
1791 && (temp1 = prev_active_insn (temp))
1792 && GET_CODE (temp1) == INSN
1793 && GET_CODE (PATTERN (temp1)) == SET
1795 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1797 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1798 == SET_DEST (PATTERN (temp1)))
1800 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1801 /* If this isn't true, cse will do the job. */
1802 && ! no_labels_between_p (temp1, temp))
1804 /* Get the if_then_else from the condjump. */
1805 rtx choice = SET_SRC (PATTERN (insn));
1806 if (GET_CODE (choice) == IF_THEN_ELSE
1807 && (GET_CODE (XEXP (choice, 0)) == EQ
1808 || GET_CODE (XEXP (choice, 0)) == NE))
1810 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1815 /* Get the place that condjump will jump to
1816 if it is reached from here. */
1817 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1819 ultimate = XEXP (choice, 1);
1821 ultimate = XEXP (choice, 2);
1822 /* Get it as a CODE_LABEL. */
1823 if (ultimate == pc_rtx)
1824 ultimate = get_label_after (insn);
1826 /* Get the label out of the LABEL_REF. */
1827 ultimate = XEXP (ultimate, 0);
1829 /* Insert the jump immediately before TEMP, specifically
1830 after the label that is between TEMP1 and TEMP. */
1831 last_insn = PREV_INSN (temp);
1833 /* If we would be branching to the next insn, the jump
1834 would immediately be deleted and the re-inserted in
1835 a subsequent pass over the code. So don't do anything
1837 if (next_active_insn (last_insn)
1838 != next_active_insn (ultimate))
1840 emit_barrier_after (last_insn);
1841 p = emit_jump_insn_after (gen_jump (ultimate),
1843 JUMP_LABEL (p) = ultimate;
1844 ++LABEL_NUSES (ultimate);
1845 if (INSN_UID (ultimate) < max_jump_chain
1846 && INSN_CODE (p) < max_jump_chain)
1848 jump_chain[INSN_UID (p)]
1849 = jump_chain[INSN_UID (ultimate)];
1850 jump_chain[INSN_UID (ultimate)] = p;
1858 /* Detect a conditional jump going to the same place
1859 as an immediately following unconditional jump. */
1860 else if (this_is_condjump
1861 && (temp = next_active_insn (insn)) != 0
1862 && simplejump_p (temp)
1863 && (next_active_insn (JUMP_LABEL (insn))
1864 == next_active_insn (JUMP_LABEL (temp))))
1870 /* Detect a conditional jump jumping over an unconditional jump. */
1872 else if ((this_is_condjump || this_is_condjump_in_parallel)
1873 && ! this_is_simplejump
1874 && reallabelprev != 0
1875 && GET_CODE (reallabelprev) == JUMP_INSN
1876 && prev_active_insn (reallabelprev) == insn
1877 && no_labels_between_p (insn, reallabelprev)
1878 && simplejump_p (reallabelprev))
1880 /* When we invert the unconditional jump, we will be
1881 decrementing the usage count of its old label.
1882 Make sure that we don't delete it now because that
1883 might cause the following code to be deleted. */
1884 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1885 rtx prev_label = JUMP_LABEL (insn);
1888 ++LABEL_NUSES (prev_label);
1890 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1892 /* It is very likely that if there are USE insns before
1893 this jump, they hold REG_DEAD notes. These REG_DEAD
1894 notes are no longer valid due to this optimization,
1895 and will cause the life-analysis that following passes
1896 (notably delayed-branch scheduling) to think that
1897 these registers are dead when they are not.
1899 To prevent this trouble, we just remove the USE insns
1900 from the insn chain. */
1902 while (prev_uses && GET_CODE (prev_uses) == INSN
1903 && GET_CODE (PATTERN (prev_uses)) == USE)
1905 rtx useless = prev_uses;
1906 prev_uses = prev_nonnote_insn (prev_uses);
1907 delete_insn (useless);
1910 delete_insn (reallabelprev);
1915 /* We can now safely delete the label if it is unreferenced
1916 since the delete_insn above has deleted the BARRIER. */
1917 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1918 delete_insn (prev_label);
1923 /* Detect a jump to a jump. */
1925 nlabel = follow_jumps (JUMP_LABEL (insn));
1926 if (nlabel != JUMP_LABEL (insn)
1927 && redirect_jump (insn, nlabel))
1933 /* Look for if (foo) bar; else break; */
1934 /* The insns look like this:
1935 insn = condjump label1;
1936 ...range1 (some insns)...
1939 ...range2 (some insns)...
1940 jump somewhere unconditionally
1943 rtx label1 = next_label (insn);
1944 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1945 /* Don't do this optimization on the first round, so that
1946 jump-around-a-jump gets simplified before we ask here
1947 whether a jump is unconditional.
1949 Also don't do it when we are called after reload since
1950 it will confuse reorg. */
1952 && (reload_completed ? ! flag_delayed_branch : 1)
1953 /* Make sure INSN is something we can invert. */
1954 && condjump_p (insn)
1956 && JUMP_LABEL (insn) == label1
1957 && LABEL_NUSES (label1) == 1
1958 && GET_CODE (range1end) == JUMP_INSN
1959 && simplejump_p (range1end))
1961 rtx label2 = next_label (label1);
1962 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1963 if (range1end != range2end
1964 && JUMP_LABEL (range1end) == label2
1965 && GET_CODE (range2end) == JUMP_INSN
1966 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1967 /* Invert the jump condition, so we
1968 still execute the same insns in each case. */
1969 && invert_jump (insn, label1))
1971 rtx range1beg = next_active_insn (insn);
1972 rtx range2beg = next_active_insn (label1);
1973 rtx range1after, range2after;
1974 rtx range1before, range2before;
1977 /* Include in each range any notes before it, to be
1978 sure that we get the line number note if any, even
1979 if there are other notes here. */
1980 while (PREV_INSN (range1beg)
1981 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1982 range1beg = PREV_INSN (range1beg);
1984 while (PREV_INSN (range2beg)
1985 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1986 range2beg = PREV_INSN (range2beg);
1988 /* Don't move NOTEs for blocks or loops; shift them
1989 outside the ranges, where they'll stay put. */
1990 range1beg = squeeze_notes (range1beg, range1end);
1991 range2beg = squeeze_notes (range2beg, range2end);
1993 /* Get current surrounds of the 2 ranges. */
1994 range1before = PREV_INSN (range1beg);
1995 range2before = PREV_INSN (range2beg);
1996 range1after = NEXT_INSN (range1end);
1997 range2after = NEXT_INSN (range2end);
1999 /* Splice range2 where range1 was. */
2000 NEXT_INSN (range1before) = range2beg;
2001 PREV_INSN (range2beg) = range1before;
2002 NEXT_INSN (range2end) = range1after;
2003 PREV_INSN (range1after) = range2end;
2004 /* Splice range1 where range2 was. */
2005 NEXT_INSN (range2before) = range1beg;
2006 PREV_INSN (range1beg) = range2before;
2007 NEXT_INSN (range1end) = range2after;
2008 PREV_INSN (range2after) = range1end;
2010 /* Check for a loop end note between the end of
2011 range2, and the next code label. If there is one,
2012 then what we have really seen is
2013 if (foo) break; end_of_loop;
2014 and moved the break sequence outside the loop.
2015 We must move the LOOP_END note to where the
2016 loop really ends now, or we will confuse loop
2017 optimization. Stop if we find a LOOP_BEG note
2018 first, since we don't want to move the LOOP_END
2019 note in that case. */
2020 for (;range2after != label2; range2after = rangenext)
2022 rangenext = NEXT_INSN (range2after);
2023 if (GET_CODE (range2after) == NOTE)
2025 if (NOTE_LINE_NUMBER (range2after)
2026 == NOTE_INSN_LOOP_END)
2028 NEXT_INSN (PREV_INSN (range2after))
2030 PREV_INSN (rangenext)
2031 = PREV_INSN (range2after);
2032 PREV_INSN (range2after)
2033 = PREV_INSN (range1beg);
2034 NEXT_INSN (range2after) = range1beg;
2035 NEXT_INSN (PREV_INSN (range1beg))
2037 PREV_INSN (range1beg) = range2after;
2039 else if (NOTE_LINE_NUMBER (range2after)
2040 == NOTE_INSN_LOOP_BEG)
2050 /* Now that the jump has been tensioned,
2051 try cross jumping: check for identical code
2052 before the jump and before its target label. */
2054 /* First, cross jumping of conditional jumps: */
2056 if (cross_jump && condjump_p (insn))
2058 rtx newjpos, newlpos;
2059 rtx x = prev_real_insn (JUMP_LABEL (insn));
2061 /* A conditional jump may be crossjumped
2062 only if the place it jumps to follows
2063 an opposing jump that comes back here. */
2065 if (x != 0 && ! jump_back_p (x, insn))
2066 /* We have no opposing jump;
2067 cannot cross jump this insn. */
2071 /* TARGET is nonzero if it is ok to cross jump
2072 to code before TARGET. If so, see if matches. */
2074 find_cross_jump (insn, x, 2,
2075 &newjpos, &newlpos);
2079 do_cross_jump (insn, newjpos, newlpos);
2080 /* Make the old conditional jump
2081 into an unconditional one. */
2082 SET_SRC (PATTERN (insn))
2083 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
2084 INSN_CODE (insn) = -1;
2085 emit_barrier_after (insn);
2086 /* Add to jump_chain unless this is a new label
2087 whose UID is too large. */
2088 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
2090 jump_chain[INSN_UID (insn)]
2091 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2092 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2099 /* Cross jumping of unconditional jumps:
2100 a few differences. */
2102 if (cross_jump && simplejump_p (insn))
2104 rtx newjpos, newlpos;
2109 /* TARGET is nonzero if it is ok to cross jump
2110 to code before TARGET. If so, see if matches. */
2111 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2112 &newjpos, &newlpos);
2114 /* If cannot cross jump to code before the label,
2115 see if we can cross jump to another jump to
2117 /* Try each other jump to this label. */
2118 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2119 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2120 target != 0 && newjpos == 0;
2121 target = jump_chain[INSN_UID (target)])
2123 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2124 /* Ignore TARGET if it's deleted. */
2125 && ! INSN_DELETED_P (target))
2126 find_cross_jump (insn, target, 2,
2127 &newjpos, &newlpos);
2131 do_cross_jump (insn, newjpos, newlpos);
2137 /* This code was dead in the previous jump.c! */
2138 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2140 /* Return insns all "jump to the same place"
2141 so we can cross-jump between any two of them. */
2143 rtx newjpos, newlpos, target;
2147 /* If cannot cross jump to code before the label,
2148 see if we can cross jump to another jump to
2150 /* Try each other jump to this label. */
2151 for (target = jump_chain[0];
2152 target != 0 && newjpos == 0;
2153 target = jump_chain[INSN_UID (target)])
2155 && ! INSN_DELETED_P (target)
2156 && GET_CODE (PATTERN (target)) == RETURN)
2157 find_cross_jump (insn, target, 2,
2158 &newjpos, &newlpos);
2162 do_cross_jump (insn, newjpos, newlpos);
2173 /* Delete extraneous line number notes.
2174 Note that two consecutive notes for different lines are not really
2175 extraneous. There should be some indication where that line belonged,
2176 even if it became empty. */
2181 for (insn = f; insn; insn = NEXT_INSN (insn))
2182 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2184 /* Delete this note if it is identical to previous note. */
2186 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2187 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2200 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2201 in front of it. If the machine allows it at this point (we might be
2202 after reload for a leaf routine), it will improve optimization for it
2203 to be there. We do this both here and at the start of this pass since
2204 the RETURN might have been deleted by some of our optimizations. */
2205 insn = get_last_insn ();
2206 while (insn && GET_CODE (insn) == NOTE)
2207 insn = PREV_INSN (insn);
2209 if (insn && GET_CODE (insn) != BARRIER)
2211 emit_jump_insn (gen_return ());
2217 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2218 If so, delete it, and record that this function can drop off the end. */
2224 /* One label can follow the end-note: the return label. */
2225 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2226 /* Ordinary insns can follow it if returning a structure. */
2227 || GET_CODE (insn) == INSN
2228 /* If machine uses explicit RETURN insns, no epilogue,
2229 then one of them follows the note. */
2230 || (GET_CODE (insn) == JUMP_INSN
2231 && GET_CODE (PATTERN (insn)) == RETURN)
2232 /* A barrier can follow the return insn. */
2233 || GET_CODE (insn) == BARRIER
2234 /* Other kinds of notes can follow also. */
2235 || (GET_CODE (insn) == NOTE
2236 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2237 insn = PREV_INSN (insn);
2240 /* Report if control can fall through at the end of the function. */
2241 if (insn && GET_CODE (insn) == NOTE
2242 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2248 /* Show JUMP_CHAIN no longer valid. */
2252 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2253 jump. Assume that this unconditional jump is to the exit test code. If
2254 the code is sufficiently simple, make a copy of it before INSN,
2255 followed by a jump to the exit of the loop. Then delete the unconditional
2258 Return 1 if we made the change, else 0.
2260 This is only safe immediately after a regscan pass because it uses the
2261 values of regno_first_uid and regno_last_uid. */
2264 duplicate_loop_exit_test (loop_start)
2267 rtx insn, set, reg, p, link;
2270 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2272 int max_reg = max_reg_num ();
2275 /* Scan the exit code. We do not perform this optimization if any insn:
2279 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2280 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2281 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2284 Also, don't do this if the exit code is more than 20 insns. */
2286 for (insn = exitcode;
2288 && ! (GET_CODE (insn) == NOTE
2289 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2290 insn = NEXT_INSN (insn))
2292 switch (GET_CODE (insn))
2298 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2299 a jump immediately after the loop start that branches outside
2300 the loop but within an outer loop, near the exit test.
2301 If we copied this exit test and created a phony
2302 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2303 before the exit test look like these could be safely moved
2304 out of the loop even if they actually may be never executed.
2305 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2307 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2308 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2309 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2310 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2315 if (++num_insns > 20
2316 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2317 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2323 /* Unless INSN is zero, we can do the optimization. */
2329 /* See if any insn sets a register only used in the loop exit code and
2330 not a user variable. If so, replace it with a new register. */
2331 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2332 if (GET_CODE (insn) == INSN
2333 && (set = single_set (insn)) != 0
2334 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2335 || (GET_CODE (reg) == SUBREG
2336 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2337 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2338 && regno_first_uid[REGNO (reg)] == INSN_UID (insn))
2340 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2341 if (regno_last_uid[REGNO (reg)] == INSN_UID (p))
2346 /* We can do the replacement. Allocate reg_map if this is the
2347 first replacement we found. */
2350 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2351 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2354 REG_LOOP_TEST_P (reg) = 1;
2356 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2360 /* Now copy each insn. */
2361 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2362 switch (GET_CODE (insn))
2365 copy = emit_barrier_before (loop_start);
2368 /* Only copy line-number notes. */
2369 if (NOTE_LINE_NUMBER (insn) >= 0)
2371 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2372 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2377 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2379 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2381 mark_jump_label (PATTERN (copy), copy, 0);
2383 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2385 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2386 if (REG_NOTE_KIND (link) != REG_LABEL)
2388 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
2389 XEXP (link, 0), REG_NOTES (copy)));
2390 if (reg_map && REG_NOTES (copy))
2391 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2395 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2397 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2398 mark_jump_label (PATTERN (copy), copy, 0);
2399 if (REG_NOTES (insn))
2401 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2403 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2406 /* If this is a simple jump, add it to the jump chain. */
2408 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2409 && simplejump_p (copy))
2411 jump_chain[INSN_UID (copy)]
2412 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2413 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2421 /* Now clean up by emitting a jump to the end label and deleting the jump
2422 at the start of the loop. */
2423 if (! copy || GET_CODE (copy) != BARRIER)
2425 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2427 mark_jump_label (PATTERN (copy), copy, 0);
2428 if (INSN_UID (copy) < max_jump_chain
2429 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2431 jump_chain[INSN_UID (copy)]
2432 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2433 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2435 emit_barrier_before (loop_start);
2438 /* Mark the exit code as the virtual top of the converted loop. */
2439 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2441 delete_insn (next_nonnote_insn (loop_start));
2446 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2447 loop-end notes between START and END out before START. Assume that
2448 END is not such a note. START may be such a note. Returns the value
2449 of the new starting insn, which may be different if the original start
2453 squeeze_notes (start, end)
2459 for (insn = start; insn != end; insn = next)
2461 next = NEXT_INSN (insn);
2462 if (GET_CODE (insn) == NOTE
2463 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2464 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2465 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2466 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2467 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2468 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2474 rtx prev = PREV_INSN (insn);
2475 PREV_INSN (insn) = PREV_INSN (start);
2476 NEXT_INSN (insn) = start;
2477 NEXT_INSN (PREV_INSN (insn)) = insn;
2478 PREV_INSN (NEXT_INSN (insn)) = insn;
2479 NEXT_INSN (prev) = next;
2480 PREV_INSN (next) = prev;
2488 /* Compare the instructions before insn E1 with those before E2
2489 to find an opportunity for cross jumping.
2490 (This means detecting identical sequences of insns followed by
2491 jumps to the same place, or followed by a label and a jump
2492 to that label, and replacing one with a jump to the other.)
2494 Assume E1 is a jump that jumps to label E2
2495 (that is not always true but it might as well be).
2496 Find the longest possible equivalent sequences
2497 and store the first insns of those sequences into *F1 and *F2.
2498 Store zero there if no equivalent preceding instructions are found.
2500 We give up if we find a label in stream 1.
2501 Actually we could transfer that label into stream 2. */
2504 find_cross_jump (e1, e2, minimum, f1, f2)
2509 register rtx i1 = e1, i2 = e2;
2510 register rtx p1, p2;
2513 rtx last1 = 0, last2 = 0;
2514 rtx afterlast1 = 0, afterlast2 = 0;
2522 i1 = prev_nonnote_insn (i1);
2524 i2 = PREV_INSN (i2);
2525 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2526 i2 = PREV_INSN (i2);
2531 /* Don't allow the range of insns preceding E1 or E2
2532 to include the other (E2 or E1). */
2533 if (i2 == e1 || i1 == e2)
2536 /* If we will get to this code by jumping, those jumps will be
2537 tensioned to go directly to the new label (before I2),
2538 so this cross-jumping won't cost extra. So reduce the minimum. */
2539 if (GET_CODE (i1) == CODE_LABEL)
2545 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2551 /* If this is a CALL_INSN, compare register usage information.
2552 If we don't check this on stack register machines, the two
2553 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2554 numbers of stack registers in the same basic block.
2555 If we don't check this on machines with delay slots, a delay slot may
2556 be filled that clobbers a parameter expected by the subroutine.
2558 ??? We take the simple route for now and assume that if they're
2559 equal, they were constructed identically. */
2561 if (GET_CODE (i1) == CALL_INSN
2562 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2563 CALL_INSN_FUNCTION_USAGE (i2)))
2567 /* If cross_jump_death_matters is not 0, the insn's mode
2568 indicates whether or not the insn contains any stack-like
2571 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2573 /* If register stack conversion has already been done, then
2574 death notes must also be compared before it is certain that
2575 the two instruction streams match. */
2578 HARD_REG_SET i1_regset, i2_regset;
2580 CLEAR_HARD_REG_SET (i1_regset);
2581 CLEAR_HARD_REG_SET (i2_regset);
2583 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2584 if (REG_NOTE_KIND (note) == REG_DEAD
2585 && STACK_REG_P (XEXP (note, 0)))
2586 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2588 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2589 if (REG_NOTE_KIND (note) == REG_DEAD
2590 && STACK_REG_P (XEXP (note, 0)))
2591 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2593 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2602 if (lose || GET_CODE (p1) != GET_CODE (p2)
2603 || ! rtx_renumbered_equal_p (p1, p2))
2605 /* The following code helps take care of G++ cleanups. */
2609 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2610 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2611 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2612 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2613 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2614 /* If the equivalences are not to a constant, they may
2615 reference pseudos that no longer exist, so we can't
2617 && CONSTANT_P (XEXP (equiv1, 0))
2618 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2620 rtx s1 = single_set (i1);
2621 rtx s2 = single_set (i2);
2622 if (s1 != 0 && s2 != 0
2623 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2625 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2626 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2627 if (! rtx_renumbered_equal_p (p1, p2))
2629 else if (apply_change_group ())
2634 /* Insns fail to match; cross jumping is limited to the following
2638 /* Don't allow the insn after a compare to be shared by
2639 cross-jumping unless the compare is also shared.
2640 Here, if either of these non-matching insns is a compare,
2641 exclude the following insn from possible cross-jumping. */
2642 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2643 last1 = afterlast1, last2 = afterlast2, ++minimum;
2646 /* If cross-jumping here will feed a jump-around-jump
2647 optimization, this jump won't cost extra, so reduce
2649 if (GET_CODE (i1) == JUMP_INSN
2651 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2657 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2659 /* Ok, this insn is potentially includable in a cross-jump here. */
2660 afterlast1 = last1, afterlast2 = last2;
2661 last1 = i1, last2 = i2, --minimum;
2665 if (minimum <= 0 && last1 != 0 && last1 != e1)
2666 *f1 = last1, *f2 = last2;
2670 do_cross_jump (insn, newjpos, newlpos)
2671 rtx insn, newjpos, newlpos;
2673 /* Find an existing label at this point
2674 or make a new one if there is none. */
2675 register rtx label = get_label_before (newlpos);
2677 /* Make the same jump insn jump to the new point. */
2678 if (GET_CODE (PATTERN (insn)) == RETURN)
2680 /* Remove from jump chain of returns. */
2681 delete_from_jump_chain (insn);
2682 /* Change the insn. */
2683 PATTERN (insn) = gen_jump (label);
2684 INSN_CODE (insn) = -1;
2685 JUMP_LABEL (insn) = label;
2686 LABEL_NUSES (label)++;
2687 /* Add to new the jump chain. */
2688 if (INSN_UID (label) < max_jump_chain
2689 && INSN_UID (insn) < max_jump_chain)
2691 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2692 jump_chain[INSN_UID (label)] = insn;
2696 redirect_jump (insn, label);
2698 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2699 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2700 the NEWJPOS stream. */
2702 while (newjpos != insn)
2706 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2707 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2708 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2709 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2710 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2711 remove_note (newlpos, lnote);
2713 delete_insn (newjpos);
2714 newjpos = next_real_insn (newjpos);
2715 newlpos = next_real_insn (newlpos);
2719 /* Return the label before INSN, or put a new label there. */
2722 get_label_before (insn)
2727 /* Find an existing label at this point
2728 or make a new one if there is none. */
2729 label = prev_nonnote_insn (insn);
2731 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2733 rtx prev = PREV_INSN (insn);
2735 label = gen_label_rtx ();
2736 emit_label_after (label, prev);
2737 LABEL_NUSES (label) = 0;
2742 /* Return the label after INSN, or put a new label there. */
2745 get_label_after (insn)
2750 /* Find an existing label at this point
2751 or make a new one if there is none. */
2752 label = next_nonnote_insn (insn);
2754 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2756 label = gen_label_rtx ();
2757 emit_label_after (label, insn);
2758 LABEL_NUSES (label) = 0;
2763 /* Return 1 if INSN is a jump that jumps to right after TARGET
2764 only on the condition that TARGET itself would drop through.
2765 Assumes that TARGET is a conditional jump. */
2768 jump_back_p (insn, target)
2772 enum rtx_code codei, codet;
2774 if (simplejump_p (insn) || ! condjump_p (insn)
2775 || simplejump_p (target)
2776 || target != prev_real_insn (JUMP_LABEL (insn)))
2779 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2780 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2782 codei = GET_CODE (cinsn);
2783 codet = GET_CODE (ctarget);
2785 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2787 if (! can_reverse_comparison_p (cinsn, insn))
2789 codei = reverse_condition (codei);
2792 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2794 if (! can_reverse_comparison_p (ctarget, target))
2796 codet = reverse_condition (codet);
2799 return (codei == codet
2800 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2801 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2804 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2805 return non-zero if it is safe to reverse this comparison. It is if our
2806 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2807 this is known to be an integer comparison. */
2810 can_reverse_comparison_p (comparison, insn)
2816 /* If this is not actually a comparison, we can't reverse it. */
2817 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2820 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2821 /* If this is an NE comparison, it is safe to reverse it to an EQ
2822 comparison and vice versa, even for floating point. If no operands
2823 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2824 always false and NE is always true, so the reversal is also valid. */
2826 || GET_CODE (comparison) == NE
2827 || GET_CODE (comparison) == EQ)
2830 arg0 = XEXP (comparison, 0);
2832 /* Make sure ARG0 is one of the actual objects being compared. If we
2833 can't do this, we can't be sure the comparison can be reversed.
2835 Handle cc0 and a MODE_CC register. */
2836 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2842 rtx prev = prev_nonnote_insn (insn);
2843 rtx set = single_set (prev);
2845 if (set == 0 || SET_DEST (set) != arg0)
2848 arg0 = SET_SRC (set);
2850 if (GET_CODE (arg0) == COMPARE)
2851 arg0 = XEXP (arg0, 0);
2854 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2855 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2856 return (GET_CODE (arg0) == CONST_INT
2857 || (GET_MODE (arg0) != VOIDmode
2858 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2859 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2862 /* Given an rtx-code for a comparison, return the code
2863 for the negated comparison.
2864 WATCH OUT! reverse_condition is not safe to use on a jump
2865 that might be acting on the results of an IEEE floating point comparison,
2866 because of the special treatment of non-signaling nans in comparisons.
2867 Use can_reverse_comparison_p to be sure. */
2870 reverse_condition (code)
2911 /* Similar, but return the code when two operands of a comparison are swapped.
2912 This IS safe for IEEE floating-point. */
2915 swap_condition (code)
2954 /* Given a comparison CODE, return the corresponding unsigned comparison.
2955 If CODE is an equality comparison or already an unsigned comparison,
2956 CODE is returned. */
2959 unsigned_condition (code)
2989 /* Similarly, return the signed version of a comparison. */
2992 signed_condition (code)
3022 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3023 truth of CODE1 implies the truth of CODE2. */
3026 comparison_dominates_p (code1, code2)
3027 enum rtx_code code1, code2;
3035 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3040 if (code2 == LE || code2 == NE)
3045 if (code2 == GE || code2 == NE)
3050 if (code2 == LEU || code2 == NE)
3055 if (code2 == GEU || code2 == NE)
3063 /* Return 1 if INSN is an unconditional jump and nothing else. */
3069 return (GET_CODE (insn) == JUMP_INSN
3070 && GET_CODE (PATTERN (insn)) == SET
3071 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3072 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3075 /* Return nonzero if INSN is a (possibly) conditional jump
3076 and nothing more. */
3082 register rtx x = PATTERN (insn);
3083 if (GET_CODE (x) != SET)
3085 if (GET_CODE (SET_DEST (x)) != PC)
3087 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3089 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3091 if (XEXP (SET_SRC (x), 2) == pc_rtx
3092 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3093 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3095 if (XEXP (SET_SRC (x), 1) == pc_rtx
3096 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3097 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3102 /* Return nonzero if INSN is a (possibly) conditional jump
3103 and nothing more. */
3106 condjump_in_parallel_p (insn)
3109 register rtx x = PATTERN (insn);
3111 if (GET_CODE (x) != PARALLEL)
3114 x = XVECEXP (x, 0, 0);
3116 if (GET_CODE (x) != SET)
3118 if (GET_CODE (SET_DEST (x)) != PC)
3120 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3122 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3124 if (XEXP (SET_SRC (x), 2) == pc_rtx
3125 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3126 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3128 if (XEXP (SET_SRC (x), 1) == pc_rtx
3129 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3130 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3135 /* Return 1 if X is an RTX that does nothing but set the condition codes
3136 and CLOBBER or USE registers.
3137 Return -1 if X does explicitly set the condition codes,
3138 but also does other things. */
3145 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3147 if (GET_CODE (x) == PARALLEL)
3151 int other_things = 0;
3152 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3154 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3155 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3157 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3160 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3168 /* Follow any unconditional jump at LABEL;
3169 return the ultimate label reached by any such chain of jumps.
3170 If LABEL is not followed by a jump, return LABEL.
3171 If the chain loops or we can't find end, return LABEL,
3172 since that tells caller to avoid changing the insn.
3174 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3175 a USE or CLOBBER. */
3178 follow_jumps (label)
3183 register rtx value = label;
3188 && (insn = next_active_insn (value)) != 0
3189 && GET_CODE (insn) == JUMP_INSN
3190 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3191 || GET_CODE (PATTERN (insn)) == RETURN)
3192 && (next = NEXT_INSN (insn))
3193 && GET_CODE (next) == BARRIER);
3196 /* Don't chain through the insn that jumps into a loop
3197 from outside the loop,
3198 since that would create multiple loop entry jumps
3199 and prevent loop optimization. */
3201 if (!reload_completed)
3202 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3203 if (GET_CODE (tem) == NOTE
3204 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
3207 /* If we have found a cycle, make the insn jump to itself. */
3208 if (JUMP_LABEL (insn) == label)
3211 tem = next_active_insn (JUMP_LABEL (insn));
3212 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3213 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3216 value = JUMP_LABEL (insn);
3223 /* Assuming that field IDX of X is a vector of label_refs,
3224 replace each of them by the ultimate label reached by it.
3225 Return nonzero if a change is made.
3226 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3229 tension_vector_labels (x, idx)
3235 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3237 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3238 register rtx nlabel = follow_jumps (olabel);
3239 if (nlabel && nlabel != olabel)
3241 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3242 ++LABEL_NUSES (nlabel);
3243 if (--LABEL_NUSES (olabel) == 0)
3244 delete_insn (olabel);
3251 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3252 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3253 in INSN, then store one of them in JUMP_LABEL (INSN).
3254 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3255 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3256 Also, when there are consecutive labels, canonicalize on the last of them.
3258 Note that two labels separated by a loop-beginning note
3259 must be kept distinct if we have not yet done loop-optimization,
3260 because the gap between them is where loop-optimize
3261 will want to move invariant code to. CROSS_JUMP tells us
3262 that loop-optimization is done with.
3264 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3265 two labels distinct if they are separated by only USE or CLOBBER insns. */
3268 mark_jump_label (x, insn, cross_jump)
3273 register RTX_CODE code = GET_CODE (x);
3291 /* If this is a constant-pool reference, see if it is a label. */
3292 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3293 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3294 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3299 rtx label = XEXP (x, 0);
3304 if (GET_CODE (label) != CODE_LABEL)
3307 /* Ignore references to labels of containing functions. */
3308 if (LABEL_REF_NONLOCAL_P (x))
3311 /* If there are other labels following this one,
3312 replace it with the last of the consecutive labels. */
3313 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3315 if (GET_CODE (next) == CODE_LABEL)
3317 else if (cross_jump && GET_CODE (next) == INSN
3318 && (GET_CODE (PATTERN (next)) == USE
3319 || GET_CODE (PATTERN (next)) == CLOBBER))
3321 else if (GET_CODE (next) != NOTE)
3323 else if (! cross_jump
3324 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3325 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
3329 XEXP (x, 0) = label;
3330 ++LABEL_NUSES (label);
3334 if (GET_CODE (insn) == JUMP_INSN)
3335 JUMP_LABEL (insn) = label;
3337 /* If we've changed OLABEL and we had a REG_LABEL note
3338 for it, update it as well. */
3339 else if (label != olabel
3340 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3341 XEXP (note, 0) = label;
3343 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3345 else if (! find_reg_note (insn, REG_LABEL, label))
3347 rtx next = next_real_insn (label);
3348 /* Don't record labels that refer to dispatch tables.
3349 This is not necessary, since the tablejump
3350 references the same label.
3351 And if we did record them, flow.c would make worse code. */
3353 || ! (GET_CODE (next) == JUMP_INSN
3354 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3355 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
3356 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
3363 /* Do walk the labels in a vector, but not the first operand of an
3364 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3368 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3370 for (i = 0; i < XVECLEN (x, eltnum); i++)
3371 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3376 fmt = GET_RTX_FORMAT (code);
3377 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3380 mark_jump_label (XEXP (x, i), insn, cross_jump);
3381 else if (fmt[i] == 'E')
3384 for (j = 0; j < XVECLEN (x, i); j++)
3385 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3390 /* If all INSN does is set the pc, delete it,
3391 and delete the insn that set the condition codes for it
3392 if that's what the previous thing was. */
3398 register rtx set = single_set (insn);
3400 if (set && GET_CODE (SET_DEST (set)) == PC)
3401 delete_computation (insn);
3404 /* Delete INSN and recursively delete insns that compute values used only
3405 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3406 If we are running before flow.c, we need do nothing since flow.c will
3407 delete dead code. We also can't know if the registers being used are
3408 dead or not at this point.
3410 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3411 nothing other than set a register that dies in this insn, we can delete
3414 On machines with CC0, if CC0 is used in this insn, we may be able to
3415 delete the insn that set it. */
3418 delete_computation (insn)
3424 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3426 rtx prev = prev_nonnote_insn (insn);
3427 /* We assume that at this stage
3428 CC's are always set explicitly
3429 and always immediately before the jump that
3430 will use them. So if the previous insn
3431 exists to set the CC's, delete it
3432 (unless it performs auto-increments, etc.). */
3433 if (prev && GET_CODE (prev) == INSN
3434 && sets_cc0_p (PATTERN (prev)))
3436 if (sets_cc0_p (PATTERN (prev)) > 0
3437 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3438 delete_computation (prev);
3440 /* Otherwise, show that cc0 won't be used. */
3441 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
3442 cc0_rtx, REG_NOTES (prev));
3447 for (note = REG_NOTES (insn); note; note = next)
3451 next = XEXP (note, 1);
3453 if (REG_NOTE_KIND (note) != REG_DEAD
3454 /* Verify that the REG_NOTE is legitimate. */
3455 || GET_CODE (XEXP (note, 0)) != REG)
3458 for (our_prev = prev_nonnote_insn (insn);
3459 our_prev && GET_CODE (our_prev) == INSN;
3460 our_prev = prev_nonnote_insn (our_prev))
3462 /* If we reach a SEQUENCE, it is too complex to try to
3463 do anything with it, so give up. */
3464 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3467 if (GET_CODE (PATTERN (our_prev)) == USE
3468 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3469 /* reorg creates USEs that look like this. We leave them
3470 alone because reorg needs them for its own purposes. */
3473 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3475 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3478 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3480 /* If we find a SET of something else, we can't
3485 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3487 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3489 if (GET_CODE (part) == SET
3490 && SET_DEST (part) != XEXP (note, 0))
3494 if (i == XVECLEN (PATTERN (our_prev), 0))
3495 delete_computation (our_prev);
3497 else if (GET_CODE (PATTERN (our_prev)) == SET
3498 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3499 delete_computation (our_prev);
3504 /* If OUR_PREV references the register that dies here, it is an
3505 additional use. Hence any prior SET isn't dead. However, this
3506 insn becomes the new place for the REG_DEAD note. */
3507 if (reg_overlap_mentioned_p (XEXP (note, 0),
3508 PATTERN (our_prev)))
3510 XEXP (note, 1) = REG_NOTES (our_prev);
3511 REG_NOTES (our_prev) = note;
3520 /* Delete insn INSN from the chain of insns and update label ref counts.
3521 May delete some following insns as a consequence; may even delete
3522 a label elsewhere and insns that follow it.
3524 Returns the first insn after INSN that was not deleted. */
3530 register rtx next = NEXT_INSN (insn);
3531 register rtx prev = PREV_INSN (insn);
3532 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3533 register int dont_really_delete = 0;
3535 while (next && INSN_DELETED_P (next))
3536 next = NEXT_INSN (next);
3538 /* This insn is already deleted => return first following nondeleted. */
3539 if (INSN_DELETED_P (insn))
3542 /* Don't delete user-declared labels. Convert them to special NOTEs
3544 if (was_code_label && LABEL_NAME (insn) != 0
3545 && optimize && ! dont_really_delete)
3547 PUT_CODE (insn, NOTE);
3548 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3549 NOTE_SOURCE_FILE (insn) = 0;
3550 dont_really_delete = 1;
3553 /* Mark this insn as deleted. */
3554 INSN_DELETED_P (insn) = 1;
3556 /* If this is an unconditional jump, delete it from the jump chain. */
3557 if (simplejump_p (insn))
3558 delete_from_jump_chain (insn);
3560 /* If instruction is followed by a barrier,
3561 delete the barrier too. */
3563 if (next != 0 && GET_CODE (next) == BARRIER)
3565 INSN_DELETED_P (next) = 1;
3566 next = NEXT_INSN (next);
3569 /* Patch out INSN (and the barrier if any) */
3571 if (optimize && ! dont_really_delete)
3575 NEXT_INSN (prev) = next;
3576 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3577 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3578 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3583 PREV_INSN (next) = prev;
3584 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3585 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3588 if (prev && NEXT_INSN (prev) == 0)
3589 set_last_insn (prev);
3592 /* If deleting a jump, decrement the count of the label,
3593 and delete the label if it is now unused. */
3595 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3596 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3598 /* This can delete NEXT or PREV,
3599 either directly if NEXT is JUMP_LABEL (INSN),
3600 or indirectly through more levels of jumps. */
3601 delete_insn (JUMP_LABEL (insn));
3602 /* I feel a little doubtful about this loop,
3603 but I see no clean and sure alternative way
3604 to find the first insn after INSN that is not now deleted.
3605 I hope this works. */
3606 while (next && INSN_DELETED_P (next))
3607 next = NEXT_INSN (next);
3611 /* Likewise if we're deleting a dispatch table. */
3613 if (GET_CODE (insn) == JUMP_INSN
3614 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3615 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3617 rtx pat = PATTERN (insn);
3618 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3619 int len = XVECLEN (pat, diff_vec_p);
3621 for (i = 0; i < len; i++)
3622 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3623 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3624 while (next && INSN_DELETED_P (next))
3625 next = NEXT_INSN (next);
3629 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3630 prev = PREV_INSN (prev);
3632 /* If INSN was a label and a dispatch table follows it,
3633 delete the dispatch table. The tablejump must have gone already.
3634 It isn't useful to fall through into a table. */
3637 && NEXT_INSN (insn) != 0
3638 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3639 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3640 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3641 next = delete_insn (NEXT_INSN (insn));
3643 /* If INSN was a label, delete insns following it if now unreachable. */
3645 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3647 register RTX_CODE code;
3649 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3650 || code == NOTE || code == BARRIER
3651 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3654 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3655 next = NEXT_INSN (next);
3656 /* Keep going past other deleted labels to delete what follows. */
3657 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3658 next = NEXT_INSN (next);
3660 /* Note: if this deletes a jump, it can cause more
3661 deletion of unreachable code, after a different label.
3662 As long as the value from this recursive call is correct,
3663 this invocation functions correctly. */
3664 next = delete_insn (next);
3671 /* Advance from INSN till reaching something not deleted
3672 then return that. May return INSN itself. */
3675 next_nondeleted_insn (insn)
3678 while (INSN_DELETED_P (insn))
3679 insn = NEXT_INSN (insn);
3683 /* Delete a range of insns from FROM to TO, inclusive.
3684 This is for the sake of peephole optimization, so assume
3685 that whatever these insns do will still be done by a new
3686 peephole insn that will replace them. */
3689 delete_for_peephole (from, to)
3690 register rtx from, to;
3692 register rtx insn = from;
3696 register rtx next = NEXT_INSN (insn);
3697 register rtx prev = PREV_INSN (insn);
3699 if (GET_CODE (insn) != NOTE)
3701 INSN_DELETED_P (insn) = 1;
3703 /* Patch this insn out of the chain. */
3704 /* We don't do this all at once, because we
3705 must preserve all NOTEs. */
3707 NEXT_INSN (prev) = next;
3710 PREV_INSN (next) = prev;
3718 /* Note that if TO is an unconditional jump
3719 we *do not* delete the BARRIER that follows,
3720 since the peephole that replaces this sequence
3721 is also an unconditional jump in that case. */
3724 /* Invert the condition of the jump JUMP, and make it jump
3725 to label NLABEL instead of where it jumps now. */
3728 invert_jump (jump, nlabel)
3731 /* We have to either invert the condition and change the label or
3732 do neither. Either operation could fail. We first try to invert
3733 the jump. If that succeeds, we try changing the label. If that fails,
3734 we invert the jump back to what it was. */
3736 if (! invert_exp (PATTERN (jump), jump))
3739 if (redirect_jump (jump, nlabel))
3742 if (! invert_exp (PATTERN (jump), jump))
3743 /* This should just be putting it back the way it was. */
3749 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3751 Return 1 if we can do so, 0 if we cannot find a way to do so that
3752 matches a pattern. */
3755 invert_exp (x, insn)
3759 register RTX_CODE code;
3763 code = GET_CODE (x);
3765 if (code == IF_THEN_ELSE)
3767 register rtx comp = XEXP (x, 0);
3770 /* We can do this in two ways: The preferable way, which can only
3771 be done if this is not an integer comparison, is to reverse
3772 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3773 of the IF_THEN_ELSE. If we can't do either, fail. */
3775 if (can_reverse_comparison_p (comp, insn)
3776 && validate_change (insn, &XEXP (x, 0),
3777 gen_rtx (reverse_condition (GET_CODE (comp)),
3778 GET_MODE (comp), XEXP (comp, 0),
3779 XEXP (comp, 1)), 0))
3783 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3784 validate_change (insn, &XEXP (x, 2), tem, 1);
3785 return apply_change_group ();
3788 fmt = GET_RTX_FORMAT (code);
3789 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3792 if (! invert_exp (XEXP (x, i), insn))
3797 for (j = 0; j < XVECLEN (x, i); j++)
3798 if (!invert_exp (XVECEXP (x, i, j), insn))
3806 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3807 If the old jump target label is unused as a result,
3808 it and the code following it may be deleted.
3810 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3813 The return value will be 1 if the change was made, 0 if it wasn't (this
3814 can only occur for NLABEL == 0). */
3817 redirect_jump (jump, nlabel)
3820 register rtx olabel = JUMP_LABEL (jump);
3822 if (nlabel == olabel)
3825 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3828 /* If this is an unconditional branch, delete it from the jump_chain of
3829 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3830 have UID's in range and JUMP_CHAIN is valid). */
3831 if (jump_chain && (simplejump_p (jump)
3832 || GET_CODE (PATTERN (jump)) == RETURN))
3834 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3836 delete_from_jump_chain (jump);
3837 if (label_index < max_jump_chain
3838 && INSN_UID (jump) < max_jump_chain)
3840 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3841 jump_chain[label_index] = jump;
3845 JUMP_LABEL (jump) = nlabel;
3847 ++LABEL_NUSES (nlabel);
3849 if (olabel && --LABEL_NUSES (olabel) == 0)
3850 delete_insn (olabel);
3855 /* Delete the instruction JUMP from any jump chain it might be on. */
3858 delete_from_jump_chain (jump)
3862 rtx olabel = JUMP_LABEL (jump);
3864 /* Handle unconditional jumps. */
3865 if (jump_chain && olabel != 0
3866 && INSN_UID (olabel) < max_jump_chain
3867 && simplejump_p (jump))
3868 index = INSN_UID (olabel);
3869 /* Handle return insns. */
3870 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3874 if (jump_chain[index] == jump)
3875 jump_chain[index] = jump_chain[INSN_UID (jump)];
3880 for (insn = jump_chain[index];
3882 insn = jump_chain[INSN_UID (insn)])
3883 if (jump_chain[INSN_UID (insn)] == jump)
3885 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3891 /* If NLABEL is nonzero, throughout the rtx at LOC,
3892 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3893 zero, alter (RETURN) to (LABEL_REF NLABEL).
3895 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3896 validity with validate_change. Convert (set (pc) (label_ref olabel))
3899 Return 0 if we found a change we would like to make but it is invalid.
3900 Otherwise, return 1. */
3903 redirect_exp (loc, olabel, nlabel, insn)
3908 register rtx x = *loc;
3909 register RTX_CODE code = GET_CODE (x);
3913 if (code == LABEL_REF)
3915 if (XEXP (x, 0) == olabel)
3918 XEXP (x, 0) = nlabel;
3920 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3924 else if (code == RETURN && olabel == 0)
3926 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3927 if (loc == &PATTERN (insn))
3928 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3929 return validate_change (insn, loc, x, 0);
3932 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3933 && GET_CODE (SET_SRC (x)) == LABEL_REF
3934 && XEXP (SET_SRC (x), 0) == olabel)
3935 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3937 fmt = GET_RTX_FORMAT (code);
3938 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3941 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3946 for (j = 0; j < XVECLEN (x, i); j++)
3947 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3955 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3957 If the old jump target label (before the dispatch table) becomes unused,
3958 it and the dispatch table may be deleted. In that case, find the insn
3959 before the jump references that label and delete it and logical successors
3963 redirect_tablejump (jump, nlabel)
3966 register rtx olabel = JUMP_LABEL (jump);
3968 /* Add this jump to the jump_chain of NLABEL. */
3969 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3970 && INSN_UID (jump) < max_jump_chain)
3972 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3973 jump_chain[INSN_UID (nlabel)] = jump;
3976 PATTERN (jump) = gen_jump (nlabel);
3977 JUMP_LABEL (jump) = nlabel;
3978 ++LABEL_NUSES (nlabel);
3979 INSN_CODE (jump) = -1;
3981 if (--LABEL_NUSES (olabel) == 0)
3983 delete_labelref_insn (jump, olabel, 0);
3984 delete_insn (olabel);
3988 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3989 If we found one, delete it and then delete this insn if DELETE_THIS is
3990 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3993 delete_labelref_insn (insn, label, delete_this)
4000 if (GET_CODE (insn) != NOTE
4001 && reg_mentioned_p (label, PATTERN (insn)))
4012 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4013 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4027 /* Like rtx_equal_p except that it considers two REGs as equal
4028 if they renumber to the same value and considers two commutative
4029 operations to be the same if the order of the operands has been
4033 rtx_renumbered_equal_p (x, y)
4037 register RTX_CODE code = GET_CODE (x);
4043 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4044 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4045 && GET_CODE (SUBREG_REG (y)) == REG)))
4047 int reg_x = -1, reg_y = -1;
4048 int word_x = 0, word_y = 0;
4050 if (GET_MODE (x) != GET_MODE (y))
4053 /* If we haven't done any renumbering, don't
4054 make any assumptions. */
4055 if (reg_renumber == 0)
4056 return rtx_equal_p (x, y);
4060 reg_x = REGNO (SUBREG_REG (x));
4061 word_x = SUBREG_WORD (x);
4063 if (reg_renumber[reg_x] >= 0)
4065 reg_x = reg_renumber[reg_x] + word_x;
4073 if (reg_renumber[reg_x] >= 0)
4074 reg_x = reg_renumber[reg_x];
4077 if (GET_CODE (y) == SUBREG)
4079 reg_y = REGNO (SUBREG_REG (y));
4080 word_y = SUBREG_WORD (y);
4082 if (reg_renumber[reg_y] >= 0)
4084 reg_y = reg_renumber[reg_y];
4092 if (reg_renumber[reg_y] >= 0)
4093 reg_y = reg_renumber[reg_y];
4096 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4099 /* Now we have disposed of all the cases
4100 in which different rtx codes can match. */
4101 if (code != GET_CODE (y))
4113 return INTVAL (x) == INTVAL (y);
4116 /* We can't assume nonlocal labels have their following insns yet. */
4117 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4118 return XEXP (x, 0) == XEXP (y, 0);
4120 /* Two label-refs are equivalent if they point at labels
4121 in the same position in the instruction stream. */
4122 return (next_real_insn (XEXP (x, 0))
4123 == next_real_insn (XEXP (y, 0)));
4126 return XSTR (x, 0) == XSTR (y, 0);
4129 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4131 if (GET_MODE (x) != GET_MODE (y))
4134 /* For commutative operations, the RTX match if the operand match in any
4135 order. Also handle the simple binary and unary cases without a loop. */
4136 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4137 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4138 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4139 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4140 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4141 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4142 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4143 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4144 else if (GET_RTX_CLASS (code) == '1')
4145 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4147 /* Compare the elements. If any pair of corresponding elements
4148 fail to match, return 0 for the whole things. */
4150 fmt = GET_RTX_FORMAT (code);
4151 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4157 if (XWINT (x, i) != XWINT (y, i))
4162 if (XINT (x, i) != XINT (y, i))
4167 if (strcmp (XSTR (x, i), XSTR (y, i)))
4172 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4177 if (XEXP (x, i) != XEXP (y, i))
4184 if (XVECLEN (x, i) != XVECLEN (y, i))
4186 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4187 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4198 /* If X is a hard register or equivalent to one or a subregister of one,
4199 return the hard register number. If X is a pseudo register that was not
4200 assigned a hard register, return the pseudo register number. Otherwise,
4201 return -1. Any rtx is valid for X. */
4207 if (GET_CODE (x) == REG)
4209 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4210 return reg_renumber[REGNO (x)];
4213 if (GET_CODE (x) == SUBREG)
4215 int base = true_regnum (SUBREG_REG (x));
4216 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4217 return SUBREG_WORD (x) + base;
4222 /* Optimize code of the form:
4224 for (x = a[i]; x; ...)
4226 for (x = a[i]; x; ...)
4230 Loop optimize will change the above code into
4234 { ...; if (! (x = ...)) break; }
4237 { ...; if (! (x = ...)) break; }
4240 In general, if the first test fails, the program can branch
4241 directly to `foo' and skip the second try which is doomed to fail.
4242 We run this after loop optimization and before flow analysis. */
4244 /* When comparing the insn patterns, we track the fact that different
4245 pseudo-register numbers may have been used in each computation.
4246 The following array stores an equivalence -- same_regs[I] == J means
4247 that pseudo register I was used in the first set of tests in a context
4248 where J was used in the second set. We also count the number of such
4249 pending equivalences. If nonzero, the expressions really aren't the
4252 static int *same_regs;
4254 static int num_same_regs;
4256 /* Track any registers modified between the target of the first jump and
4257 the second jump. They never compare equal. */
4259 static char *modified_regs;
4261 /* Record if memory was modified. */
4263 static int modified_mem;
4265 /* Called via note_stores on each insn between the target of the first
4266 branch and the second branch. It marks any changed registers. */
4269 mark_modified_reg (dest, x)
4275 if (GET_CODE (dest) == SUBREG)
4276 dest = SUBREG_REG (dest);
4278 if (GET_CODE (dest) == MEM)
4281 if (GET_CODE (dest) != REG)
4284 regno = REGNO (dest);
4285 if (regno >= FIRST_PSEUDO_REGISTER)
4286 modified_regs[regno] = 1;
4288 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4289 modified_regs[regno + i] = 1;
4292 /* F is the first insn in the chain of insns. */
4295 thread_jumps (f, max_reg, flag_before_loop)
4298 int flag_before_loop;
4300 /* Basic algorithm is to find a conditional branch,
4301 the label it may branch to, and the branch after
4302 that label. If the two branches test the same condition,
4303 walk back from both branch paths until the insn patterns
4304 differ, or code labels are hit. If we make it back to
4305 the target of the first branch, then we know that the first branch
4306 will either always succeed or always fail depending on the relative
4307 senses of the two branches. So adjust the first branch accordingly
4310 rtx label, b1, b2, t1, t2;
4311 enum rtx_code code1, code2;
4312 rtx b1op0, b1op1, b2op0, b2op1;
4317 /* Allocate register tables and quick-reset table. */
4318 modified_regs = (char *) alloca (max_reg * sizeof (char));
4319 same_regs = (int *) alloca (max_reg * sizeof (int));
4320 all_reset = (int *) alloca (max_reg * sizeof (int));
4321 for (i = 0; i < max_reg; i++)
4328 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4330 /* Get to a candidate branch insn. */
4331 if (GET_CODE (b1) != JUMP_INSN
4332 || ! condjump_p (b1) || simplejump_p (b1)
4333 || JUMP_LABEL (b1) == 0)
4336 bzero (modified_regs, max_reg * sizeof (char));
4339 bcopy ((char *) all_reset, (char *) same_regs,
4340 max_reg * sizeof (int));
4343 label = JUMP_LABEL (b1);
4345 /* Look for a branch after the target. Record any registers and
4346 memory modified between the target and the branch. Stop when we
4347 get to a label since we can't know what was changed there. */
4348 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4350 if (GET_CODE (b2) == CODE_LABEL)
4353 else if (GET_CODE (b2) == JUMP_INSN)
4355 /* If this is an unconditional jump and is the only use of
4356 its target label, we can follow it. */
4357 if (simplejump_p (b2)
4358 && JUMP_LABEL (b2) != 0
4359 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4361 b2 = JUMP_LABEL (b2);
4368 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4371 if (GET_CODE (b2) == CALL_INSN)
4374 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4375 if (call_used_regs[i] && ! fixed_regs[i]
4376 && i != STACK_POINTER_REGNUM
4377 && i != FRAME_POINTER_REGNUM
4378 && i != HARD_FRAME_POINTER_REGNUM
4379 && i != ARG_POINTER_REGNUM)
4380 modified_regs[i] = 1;
4383 note_stores (PATTERN (b2), mark_modified_reg);
4386 /* Check the next candidate branch insn from the label
4389 || GET_CODE (b2) != JUMP_INSN
4391 || ! condjump_p (b2)
4392 || simplejump_p (b2))
4395 /* Get the comparison codes and operands, reversing the
4396 codes if appropriate. If we don't have comparison codes,
4397 we can't do anything. */
4398 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4399 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4400 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4401 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4402 code1 = reverse_condition (code1);
4404 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4405 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4406 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4407 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4408 code2 = reverse_condition (code2);
4410 /* If they test the same things and knowing that B1 branches
4411 tells us whether or not B2 branches, check if we
4412 can thread the branch. */
4413 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4414 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4415 && (comparison_dominates_p (code1, code2)
4416 || comparison_dominates_p (code1, reverse_condition (code2))))
4418 t1 = prev_nonnote_insn (b1);
4419 t2 = prev_nonnote_insn (b2);
4421 while (t1 != 0 && t2 != 0)
4425 /* We have reached the target of the first branch.
4426 If there are no pending register equivalents,
4427 we know that this branch will either always
4428 succeed (if the senses of the two branches are
4429 the same) or always fail (if not). */
4432 if (num_same_regs != 0)
4435 if (comparison_dominates_p (code1, code2))
4436 new_label = JUMP_LABEL (b2);
4438 new_label = get_label_after (b2);
4440 if (JUMP_LABEL (b1) != new_label)
4442 rtx prev = PREV_INSN (new_label);
4444 if (flag_before_loop
4445 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4447 /* Don't thread to the loop label. If a loop
4448 label is reused, loop optimization will
4449 be disabled for that loop. */
4450 new_label = gen_label_rtx ();
4451 emit_label_after (new_label, PREV_INSN (prev));
4453 changed |= redirect_jump (b1, new_label);
4458 /* If either of these is not a normal insn (it might be
4459 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4460 have already been skipped above.) Similarly, fail
4461 if the insns are different. */
4462 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4463 || recog_memoized (t1) != recog_memoized (t2)
4464 || ! rtx_equal_for_thread_p (PATTERN (t1),
4468 t1 = prev_nonnote_insn (t1);
4469 t2 = prev_nonnote_insn (t2);
4476 /* This is like RTX_EQUAL_P except that it knows about our handling of
4477 possibly equivalent registers and knows to consider volatile and
4478 modified objects as not equal.
4480 YINSN is the insn containing Y. */
4483 rtx_equal_for_thread_p (x, y, yinsn)
4489 register enum rtx_code code;
4492 code = GET_CODE (x);
4493 /* Rtx's of different codes cannot be equal. */
4494 if (code != GET_CODE (y))
4497 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4498 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4500 if (GET_MODE (x) != GET_MODE (y))
4503 /* For commutative operations, the RTX match if the operand match in any
4504 order. Also handle the simple binary and unary cases without a loop. */
4505 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4506 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4507 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4508 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4509 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4510 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4511 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4512 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4513 else if (GET_RTX_CLASS (code) == '1')
4514 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4516 /* Handle special-cases first. */
4520 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4523 /* If neither is user variable or hard register, check for possible
4525 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4526 || REGNO (x) < FIRST_PSEUDO_REGISTER
4527 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4530 if (same_regs[REGNO (x)] == -1)
4532 same_regs[REGNO (x)] = REGNO (y);
4535 /* If this is the first time we are seeing a register on the `Y'
4536 side, see if it is the last use. If not, we can't thread the
4537 jump, so mark it as not equivalent. */
4538 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
4544 return (same_regs[REGNO (x)] == REGNO (y));
4549 /* If memory modified or either volatile, not equivalent.
4550 Else, check address. */
4551 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4554 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4557 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4563 /* Cancel a pending `same_regs' if setting equivalenced registers.
4564 Then process source. */
4565 if (GET_CODE (SET_DEST (x)) == REG
4566 && GET_CODE (SET_DEST (y)) == REG)
4568 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4570 same_regs[REGNO (SET_DEST (x))] = -1;
4573 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4577 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4580 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4583 return XEXP (x, 0) == XEXP (y, 0);
4586 return XSTR (x, 0) == XSTR (y, 0);
4592 fmt = GET_RTX_FORMAT (code);
4593 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4598 if (XWINT (x, i) != XWINT (y, i))
4604 if (XINT (x, i) != XINT (y, i))
4610 /* Two vectors must have the same length. */
4611 if (XVECLEN (x, i) != XVECLEN (y, i))
4614 /* And the corresponding elements must match. */
4615 for (j = 0; j < XVECLEN (x, i); j++)
4616 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4617 XVECEXP (y, i, j), yinsn) == 0)
4622 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4628 if (strcmp (XSTR (x, i), XSTR (y, i)))
4633 /* These are just backpointers, so they don't matter. */
4639 /* It is believed that rtx's at this level will never
4640 contain anything but integers and other rtx's,
4641 except for within LABEL_REFs and SYMBOL_REFs. */