1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-95, 1996 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
57 #include "hard-reg-set.h"
59 #include "insn-config.h"
60 #include "insn-flags.h"
65 /* ??? Eventually must record somehow the labels used by jumps
66 from nested functions. */
67 /* Pre-record the next or previous real insn for each label?
68 No, this pass is very fast anyway. */
69 /* Condense consecutive labels?
70 This would make life analysis faster, maybe. */
71 /* Optimize jump y; x: ... y: jumpif... x?
72 Don't know if it is worth bothering with. */
73 /* Optimize two cases of conditional jump to conditional jump?
74 This can never delete any instruction or make anything dead,
75 or even change what is live at any point.
76 So perhaps let combiner do it. */
78 /* Vector indexed by uid.
79 For each CODE_LABEL, index by its uid to get first unconditional jump
80 that jumps to the label.
81 For each JUMP_INSN, index by its uid to get the next unconditional jump
82 that jumps to the same label.
83 Element 0 is the start of a chain of all return insns.
84 (It is safe to use element 0 because insn uid 0 is not used. */
86 static rtx *jump_chain;
88 /* List of labels referred to from initializers.
89 These can never be deleted. */
92 /* Maximum index in jump_chain. */
94 static int max_jump_chain;
96 /* Set nonzero by jump_optimize if control can fall through
97 to the end of the function. */
100 /* Indicates whether death notes are significant in cross jump analysis.
101 Normally they are not significant, because of A and B jump to C,
102 and R dies in A, it must die in B. But this might not be true after
103 stack register conversion, and we must compare death notes in that
106 static int cross_jump_death_matters = 0;
108 static int duplicate_loop_exit_test PROTO((rtx));
109 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
110 static void do_cross_jump PROTO((rtx, rtx, rtx));
111 static int jump_back_p PROTO((rtx, rtx));
112 static int tension_vector_labels PROTO((rtx, int));
113 static void mark_jump_label PROTO((rtx, rtx, int));
114 static void delete_computation PROTO((rtx));
115 static void delete_from_jump_chain PROTO((rtx));
116 static int delete_labelref_insn PROTO((rtx, rtx, int));
117 static void redirect_tablejump PROTO((rtx, rtx));
119 /* Delete no-op jumps and optimize jumps to jumps
120 and jumps around jumps.
121 Delete unused labels and unreachable code.
123 If CROSS_JUMP is 1, detect matching code
124 before a jump and its destination and unify them.
125 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
127 If NOOP_MOVES is nonzero, delete no-op move insns.
129 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
130 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
132 If `optimize' is zero, don't change any code,
133 just determine whether control drops off the end of the function.
134 This case occurs when we have -W and not -O.
135 It works because `delete_insn' checks the value of `optimize'
136 and refrains from actually deleting when that is 0. */
139 jump_optimize (f, cross_jump, noop_moves, after_regscan)
145 register rtx insn, next, note;
151 cross_jump_death_matters = (cross_jump == 2);
153 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
154 notes whose labels don't occur in the insn any more. */
156 for (insn = f; insn; insn = NEXT_INSN (insn))
158 if (GET_CODE (insn) == CODE_LABEL)
159 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
160 else if (GET_CODE (insn) == JUMP_INSN)
161 JUMP_LABEL (insn) = 0;
162 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
163 for (note = REG_NOTES (insn); note; note = next)
165 next = XEXP (note, 1);
166 if (REG_NOTE_KIND (note) == REG_LABEL
167 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
168 remove_note (insn, note);
171 if (INSN_UID (insn) > max_uid)
172 max_uid = INSN_UID (insn);
177 /* Delete insns following barriers, up to next label. */
179 for (insn = f; insn;)
181 if (GET_CODE (insn) == BARRIER)
183 insn = NEXT_INSN (insn);
184 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
186 if (GET_CODE (insn) == NOTE
187 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
188 insn = NEXT_INSN (insn);
190 insn = delete_insn (insn);
192 /* INSN is now the code_label. */
195 insn = NEXT_INSN (insn);
198 /* Leave some extra room for labels and duplicate exit test insns
200 max_jump_chain = max_uid * 14 / 10;
201 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
202 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
204 /* Mark the label each jump jumps to.
205 Combine consecutive labels, and count uses of labels.
207 For each label, make a chain (using `jump_chain')
208 of all the *unconditional* jumps that jump to it;
209 also make a chain of all returns. */
211 for (insn = f; insn; insn = NEXT_INSN (insn))
212 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
213 && ! INSN_DELETED_P (insn))
215 mark_jump_label (PATTERN (insn), insn, cross_jump);
216 if (GET_CODE (insn) == JUMP_INSN)
218 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
220 jump_chain[INSN_UID (insn)]
221 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
222 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
224 if (GET_CODE (PATTERN (insn)) == RETURN)
226 jump_chain[INSN_UID (insn)] = jump_chain[0];
227 jump_chain[0] = insn;
232 /* Keep track of labels used from static data;
233 they cannot ever be deleted. */
235 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
236 LABEL_NUSES (XEXP (insn, 0))++;
238 check_exception_handler_labels ();
240 /* Keep track of labels used for marking handlers for exception
241 regions; they cannot usually be deleted. */
243 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
244 LABEL_NUSES (XEXP (insn, 0))++;
246 exception_optimize ();
248 /* Delete all labels already not referenced.
249 Also find the last insn. */
252 for (insn = f; insn; )
254 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
255 insn = delete_insn (insn);
259 insn = NEXT_INSN (insn);
265 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
266 If so record that this function can drop off the end. */
272 /* One label can follow the end-note: the return label. */
273 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
274 /* Ordinary insns can follow it if returning a structure. */
275 || GET_CODE (insn) == INSN
276 /* If machine uses explicit RETURN insns, no epilogue,
277 then one of them follows the note. */
278 || (GET_CODE (insn) == JUMP_INSN
279 && GET_CODE (PATTERN (insn)) == RETURN)
280 /* A barrier can follow the return insn. */
281 || GET_CODE (insn) == BARRIER
282 /* Other kinds of notes can follow also. */
283 || (GET_CODE (insn) == NOTE
284 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
285 insn = PREV_INSN (insn);
288 /* Report if control can fall through at the end of the function. */
289 if (insn && GET_CODE (insn) == NOTE
290 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
291 && ! INSN_DELETED_P (insn))
294 /* Zero the "deleted" flag of all the "deleted" insns. */
295 for (insn = f; insn; insn = NEXT_INSN (insn))
296 INSN_DELETED_P (insn) = 0;
303 /* If we fall through to the epilogue, see if we can insert a RETURN insn
304 in front of it. If the machine allows it at this point (we might be
305 after reload for a leaf routine), it will improve optimization for it
307 insn = get_last_insn ();
308 while (insn && GET_CODE (insn) == NOTE)
309 insn = PREV_INSN (insn);
311 if (insn && GET_CODE (insn) != BARRIER)
313 emit_jump_insn (gen_return ());
320 for (insn = f; insn; )
322 next = NEXT_INSN (insn);
324 if (GET_CODE (insn) == INSN)
326 register rtx body = PATTERN (insn);
328 /* Combine stack_adjusts with following push_insns. */
330 if (GET_CODE (body) == SET
331 && SET_DEST (body) == stack_pointer_rtx
332 && GET_CODE (SET_SRC (body)) == PLUS
333 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
334 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
335 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
338 rtx stack_adjust_insn = insn;
339 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
340 int total_pushed = 0;
343 /* Find all successive push insns. */
345 /* Don't convert more than three pushes;
346 that starts adding too many displaced addresses
347 and the whole thing starts becoming a losing
352 p = next_nonnote_insn (p);
353 if (p == 0 || GET_CODE (p) != INSN)
356 if (GET_CODE (pbody) != SET)
358 dest = SET_DEST (pbody);
359 /* Allow a no-op move between the adjust and the push. */
360 if (GET_CODE (dest) == REG
361 && GET_CODE (SET_SRC (pbody)) == REG
362 && REGNO (dest) == REGNO (SET_SRC (pbody)))
364 if (! (GET_CODE (dest) == MEM
365 && GET_CODE (XEXP (dest, 0)) == POST_INC
366 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
369 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
370 > stack_adjust_amount)
372 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
375 /* Discard the amount pushed from the stack adjust;
376 maybe eliminate it entirely. */
377 if (total_pushed >= stack_adjust_amount)
379 delete_computation (stack_adjust_insn);
380 total_pushed = stack_adjust_amount;
383 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
384 = GEN_INT (stack_adjust_amount - total_pushed);
386 /* Change the appropriate push insns to ordinary stores. */
388 while (total_pushed > 0)
391 p = next_nonnote_insn (p);
392 if (GET_CODE (p) != INSN)
395 if (GET_CODE (pbody) == SET)
397 dest = SET_DEST (pbody);
398 if (! (GET_CODE (dest) == MEM
399 && GET_CODE (XEXP (dest, 0)) == POST_INC
400 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
402 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
403 /* If this push doesn't fully fit in the space
404 of the stack adjust that we deleted,
405 make another stack adjust here for what we
406 didn't use up. There should be peepholes
407 to recognize the resulting sequence of insns. */
408 if (total_pushed < 0)
410 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
411 GEN_INT (- total_pushed)),
416 = plus_constant (stack_pointer_rtx, total_pushed);
421 /* Detect and delete no-op move instructions
422 resulting from not allocating a parameter in a register. */
424 if (GET_CODE (body) == SET
425 && (SET_DEST (body) == SET_SRC (body)
426 || (GET_CODE (SET_DEST (body)) == MEM
427 && GET_CODE (SET_SRC (body)) == MEM
428 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
429 && ! (GET_CODE (SET_DEST (body)) == MEM
430 && MEM_VOLATILE_P (SET_DEST (body)))
431 && ! (GET_CODE (SET_SRC (body)) == MEM
432 && MEM_VOLATILE_P (SET_SRC (body))))
433 delete_computation (insn);
435 /* Detect and ignore no-op move instructions
436 resulting from smart or fortuitous register allocation. */
438 else if (GET_CODE (body) == SET)
440 int sreg = true_regnum (SET_SRC (body));
441 int dreg = true_regnum (SET_DEST (body));
443 if (sreg == dreg && sreg >= 0)
445 else if (sreg >= 0 && dreg >= 0)
448 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
449 sreg, NULL_PTR, dreg,
450 GET_MODE (SET_SRC (body)));
453 GET_MODE (tem) == GET_MODE (SET_DEST (body)))
455 /* DREG may have been the target of a REG_DEAD note in
456 the insn which makes INSN redundant. If so, reorg
457 would still think it is dead. So search for such a
458 note and delete it if we find it. */
459 if (! find_regno_note (insn, REG_UNUSED, dreg))
460 for (trial = prev_nonnote_insn (insn);
461 trial && GET_CODE (trial) != CODE_LABEL;
462 trial = prev_nonnote_insn (trial))
463 if (find_regno_note (trial, REG_DEAD, dreg))
465 remove_death (dreg, trial);
468 #ifdef PRESERVE_DEATH_INFO_REGNO_P
469 /* Deleting insn could lose a death-note for SREG
470 so don't do it if final needs accurate
472 if (PRESERVE_DEATH_INFO_REGNO_P (sreg)
473 && (trial = find_regno_note (insn, REG_DEAD, sreg)))
475 /* Change this into a USE so that we won't emit
476 code for it, but still can keep the note. */
478 = gen_rtx (USE, VOIDmode, XEXP (trial, 0));
479 /* Remove all reg notes but the REG_DEAD one. */
480 REG_NOTES (insn) = trial;
481 XEXP (trial, 1) = NULL_RTX;
488 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
489 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
491 GET_MODE (SET_DEST (body))))
493 /* This handles the case where we have two consecutive
494 assignments of the same constant to pseudos that didn't
495 get a hard reg. Each SET from the constant will be
496 converted into a SET of the spill register and an
497 output reload will be made following it. This produces
498 two loads of the same constant into the same spill
503 /* Look back for a death note for the first reg.
504 If there is one, it is no longer accurate. */
505 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
507 if ((GET_CODE (in_insn) == INSN
508 || GET_CODE (in_insn) == JUMP_INSN)
509 && find_regno_note (in_insn, REG_DEAD, dreg))
511 remove_death (dreg, in_insn);
514 in_insn = PREV_INSN (in_insn);
517 /* Delete the second load of the value. */
521 else if (GET_CODE (body) == PARALLEL)
523 /* If each part is a set between two identical registers or
524 a USE or CLOBBER, delete the insn. */
528 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
530 tem = XVECEXP (body, 0, i);
531 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
534 if (GET_CODE (tem) != SET
535 || (sreg = true_regnum (SET_SRC (tem))) < 0
536 || (dreg = true_regnum (SET_DEST (tem))) < 0
544 /* Also delete insns to store bit fields if they are no-ops. */
545 /* Not worth the hair to detect this in the big-endian case. */
546 else if (! BYTES_BIG_ENDIAN
547 && GET_CODE (body) == SET
548 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
549 && XEXP (SET_DEST (body), 2) == const0_rtx
550 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
551 && ! (GET_CODE (SET_SRC (body)) == MEM
552 && MEM_VOLATILE_P (SET_SRC (body))))
558 /* If we haven't yet gotten to reload and we have just run regscan,
559 delete any insn that sets a register that isn't used elsewhere.
560 This helps some of the optimizations below by having less insns
561 being jumped around. */
563 if (! reload_completed && after_regscan)
564 for (insn = f; insn; insn = next)
566 rtx set = single_set (insn);
568 next = NEXT_INSN (insn);
570 if (set && GET_CODE (SET_DEST (set)) == REG
571 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
572 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
573 /* We use regno_last_note_uid so as not to delete the setting
574 of a reg that's used in notes. A subsequent optimization
575 might arrange to use that reg for real. */
576 && regno_last_note_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
577 && ! side_effects_p (SET_SRC (set))
578 && ! find_reg_note (insn, REG_RETVAL, 0))
582 /* Now iterate optimizing jumps until nothing changes over one pass. */
588 for (insn = f; insn; insn = next)
591 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
593 int this_is_simplejump, this_is_condjump, reversep;
594 int this_is_condjump_in_parallel;
596 /* If NOT the first iteration, if this is the last jump pass
597 (just before final), do the special peephole optimizations.
598 Avoiding the first iteration gives ordinary jump opts
599 a chance to work before peephole opts. */
601 if (reload_completed && !first && !flag_no_peephole)
602 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
606 /* That could have deleted some insns after INSN, so check now
607 what the following insn is. */
609 next = NEXT_INSN (insn);
611 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
612 jump. Try to optimize by duplicating the loop exit test if so.
613 This is only safe immediately after regscan, because it uses
614 the values of regno_first_uid and regno_last_uid. */
615 if (after_regscan && GET_CODE (insn) == NOTE
616 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
617 && (temp1 = next_nonnote_insn (insn)) != 0
618 && simplejump_p (temp1))
620 temp = PREV_INSN (insn);
621 if (duplicate_loop_exit_test (insn))
624 next = NEXT_INSN (temp);
629 if (GET_CODE (insn) != JUMP_INSN)
632 this_is_simplejump = simplejump_p (insn);
633 this_is_condjump = condjump_p (insn);
634 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
636 /* Tension the labels in dispatch tables. */
638 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
639 changed |= tension_vector_labels (PATTERN (insn), 0);
640 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
641 changed |= tension_vector_labels (PATTERN (insn), 1);
643 /* If a dispatch table always goes to the same place,
644 get rid of it and replace the insn that uses it. */
646 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
647 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
650 rtx pat = PATTERN (insn);
651 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
652 int len = XVECLEN (pat, diff_vec_p);
653 rtx dispatch = prev_real_insn (insn);
655 for (i = 0; i < len; i++)
656 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
657 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
661 && GET_CODE (dispatch) == JUMP_INSN
662 && JUMP_LABEL (dispatch) != 0
663 /* Don't mess with a casesi insn. */
664 && !(GET_CODE (PATTERN (dispatch)) == SET
665 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
667 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
669 redirect_tablejump (dispatch,
670 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
675 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
677 /* If a jump references the end of the function, try to turn
678 it into a RETURN insn, possibly a conditional one. */
679 if (JUMP_LABEL (insn)
680 && (next_active_insn (JUMP_LABEL (insn)) == 0
681 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
683 changed |= redirect_jump (insn, NULL_RTX);
685 /* Detect jump to following insn. */
686 if (reallabelprev == insn && condjump_p (insn))
688 next = next_real_insn (JUMP_LABEL (insn));
694 /* If we have an unconditional jump preceded by a USE, try to put
695 the USE before the target and jump there. This simplifies many
696 of the optimizations below since we don't have to worry about
697 dealing with these USE insns. We only do this if the label
698 being branch to already has the identical USE or if code
699 never falls through to that label. */
701 if (this_is_simplejump
702 && (temp = prev_nonnote_insn (insn)) != 0
703 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
704 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
705 && (GET_CODE (temp1) == BARRIER
706 || (GET_CODE (temp1) == INSN
707 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
708 /* Don't do this optimization if we have a loop containing only
709 the USE instruction, and the loop start label has a usage
710 count of 1. This is because we will redo this optimization
711 everytime through the outer loop, and jump opt will never
713 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
714 && temp2 == JUMP_LABEL (insn)
715 && LABEL_NUSES (temp2) == 1))
717 if (GET_CODE (temp1) == BARRIER)
719 emit_insn_after (PATTERN (temp), temp1);
720 temp1 = NEXT_INSN (temp1);
724 redirect_jump (insn, get_label_before (temp1));
725 reallabelprev = prev_real_insn (temp1);
729 /* Simplify if (...) x = a; else x = b; by converting it
730 to x = b; if (...) x = a;
731 if B is sufficiently simple, the test doesn't involve X,
732 and nothing in the test modifies B or X.
734 If we have small register classes, we also can't do this if X
737 If the "x = b;" insn has any REG_NOTES, we don't do this because
738 of the possibility that we are running after CSE and there is a
739 REG_EQUAL note that is only valid if the branch has already been
740 taken. If we move the insn with the REG_EQUAL note, we may
741 fold the comparison to always be false in a later CSE pass.
742 (We could also delete the REG_NOTES when moving the insn, but it
743 seems simpler to not move it.) An exception is that we can move
744 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
745 value is the same as "b".
747 INSN is the branch over the `else' part.
751 TEMP to the jump insn preceding "x = a;"
753 TEMP2 to the insn that sets "x = b;"
754 TEMP3 to the insn that sets "x = a;"
755 TEMP4 to the set of "x = b"; */
757 if (this_is_simplejump
758 && (temp3 = prev_active_insn (insn)) != 0
759 && GET_CODE (temp3) == INSN
760 && (temp4 = single_set (temp3)) != 0
761 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
762 #ifdef SMALL_REGISTER_CLASSES
763 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
765 && (temp2 = next_active_insn (insn)) != 0
766 && GET_CODE (temp2) == INSN
767 && (temp4 = single_set (temp2)) != 0
768 && rtx_equal_p (SET_DEST (temp4), temp1)
769 && (GET_CODE (SET_SRC (temp4)) == REG
770 || GET_CODE (SET_SRC (temp4)) == SUBREG
771 || CONSTANT_P (SET_SRC (temp4)))
772 && (REG_NOTES (temp2) == 0
773 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
774 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
775 && XEXP (REG_NOTES (temp2), 1) == 0
776 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
778 && (temp = prev_active_insn (temp3)) != 0
779 && condjump_p (temp) && ! simplejump_p (temp)
780 /* TEMP must skip over the "x = a;" insn */
781 && prev_real_insn (JUMP_LABEL (temp)) == insn
782 && no_labels_between_p (insn, JUMP_LABEL (temp))
783 /* There must be no other entries to the "x = b;" insn. */
784 && no_labels_between_p (JUMP_LABEL (temp), temp2)
785 /* INSN must either branch to the insn after TEMP2 or the insn
786 after TEMP2 must branch to the same place as INSN. */
787 && (reallabelprev == temp2
788 || ((temp5 = next_active_insn (temp2)) != 0
789 && simplejump_p (temp5)
790 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
792 /* The test expression, X, may be a complicated test with
793 multiple branches. See if we can find all the uses of
794 the label that TEMP branches to without hitting a CALL_INSN
795 or a jump to somewhere else. */
796 rtx target = JUMP_LABEL (temp);
797 int nuses = LABEL_NUSES (target);
800 /* Set P to the first jump insn that goes around "x = a;". */
801 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
803 if (GET_CODE (p) == JUMP_INSN)
805 if (condjump_p (p) && ! simplejump_p (p)
806 && JUMP_LABEL (p) == target)
815 else if (GET_CODE (p) == CALL_INSN)
820 /* We cannot insert anything between a set of cc and its use
821 so if P uses cc0, we must back up to the previous insn. */
822 q = prev_nonnote_insn (p);
823 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
824 && sets_cc0_p (PATTERN (q)))
831 /* If we found all the uses and there was no data conflict, we
832 can move the assignment unless we can branch into the middle
835 && no_labels_between_p (p, insn)
836 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
837 && ! reg_set_between_p (temp1, p, temp3)
838 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
839 || ! reg_set_between_p (SET_SRC (temp4), p, temp2)))
841 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
844 /* Set NEXT to an insn that we know won't go away. */
845 next = next_active_insn (insn);
847 /* Delete the jump around the set. Note that we must do
848 this before we redirect the test jumps so that it won't
849 delete the code immediately following the assignment
850 we moved (which might be a jump). */
854 /* We either have two consecutive labels or a jump to
855 a jump, so adjust all the JUMP_INSNs to branch to where
857 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
858 if (GET_CODE (p) == JUMP_INSN)
859 redirect_jump (p, target);
866 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
867 to x = a; if (...) goto l; x = b;
868 if A is sufficiently simple, the test doesn't involve X,
869 and nothing in the test modifies A or X.
871 If we have small register classes, we also can't do this if X
874 If the "x = a;" insn has any REG_NOTES, we don't do this because
875 of the possibility that we are running after CSE and there is a
876 REG_EQUAL note that is only valid if the branch has already been
877 taken. If we move the insn with the REG_EQUAL note, we may
878 fold the comparison to always be false in a later CSE pass.
879 (We could also delete the REG_NOTES when moving the insn, but it
880 seems simpler to not move it.) An exception is that we can move
881 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
882 value is the same as "a".
888 TEMP to the jump insn preceding "x = a;"
890 TEMP2 to the insn that sets "x = b;"
891 TEMP3 to the insn that sets "x = a;"
892 TEMP4 to the set of "x = a"; */
894 if (this_is_simplejump
895 && (temp2 = next_active_insn (insn)) != 0
896 && GET_CODE (temp2) == INSN
897 && (temp4 = single_set (temp2)) != 0
898 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
899 #ifdef SMALL_REGISTER_CLASSES
900 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
903 && (temp3 = prev_active_insn (insn)) != 0
904 && GET_CODE (temp3) == INSN
905 && (temp4 = single_set (temp3)) != 0
906 && rtx_equal_p (SET_DEST (temp4), temp1)
907 && (GET_CODE (SET_SRC (temp4)) == REG
908 || GET_CODE (SET_SRC (temp4)) == SUBREG
909 || CONSTANT_P (SET_SRC (temp4)))
910 && (REG_NOTES (temp3) == 0
911 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
912 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
913 && XEXP (REG_NOTES (temp3), 1) == 0
914 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
916 && (temp = prev_active_insn (temp3)) != 0
917 && condjump_p (temp) && ! simplejump_p (temp)
918 /* TEMP must skip over the "x = a;" insn */
919 && prev_real_insn (JUMP_LABEL (temp)) == insn
920 && no_labels_between_p (temp, insn))
922 rtx prev_label = JUMP_LABEL (temp);
923 rtx insert_after = prev_nonnote_insn (temp);
926 /* We cannot insert anything between a set of cc and its use. */
927 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
928 && sets_cc0_p (PATTERN (insert_after)))
929 insert_after = prev_nonnote_insn (insert_after);
931 ++LABEL_NUSES (prev_label);
934 && no_labels_between_p (insert_after, temp)
935 && ! reg_referenced_between_p (temp1, insert_after, temp)
936 && ! reg_referenced_between_p (temp1, temp3,
938 && ! reg_set_between_p (temp1, insert_after, temp)
939 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
940 || ! reg_set_between_p (SET_SRC (temp4),
942 && invert_jump (temp, JUMP_LABEL (insn)))
944 emit_insn_after_with_line_notes (PATTERN (temp3),
945 insert_after, temp3);
948 /* Set NEXT to an insn that we know won't go away. */
952 if (prev_label && --LABEL_NUSES (prev_label) == 0)
953 delete_insn (prev_label);
959 /* If we have if (...) x = exp; and branches are expensive,
960 EXP is a single insn, does not have any side effects, cannot
961 trap, and is not too costly, convert this to
962 t = exp; if (...) x = t;
964 Don't do this when we have CC0 because it is unlikely to help
965 and we'd need to worry about where to place the new insn and
966 the potential for conflicts. We also can't do this when we have
967 notes on the insn for the same reason as above.
971 TEMP to the "x = exp;" insn.
972 TEMP1 to the single set in the "x = exp; insn.
975 if (! reload_completed
976 && this_is_condjump && ! this_is_simplejump
978 && (temp = next_nonnote_insn (insn)) != 0
979 && GET_CODE (temp) == INSN
980 && REG_NOTES (temp) == 0
981 && (reallabelprev == temp
982 || ((temp2 = next_active_insn (temp)) != 0
983 && simplejump_p (temp2)
984 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
985 && (temp1 = single_set (temp)) != 0
986 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
987 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
988 #ifdef SMALL_REGISTER_CLASSES
989 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
991 && GET_CODE (SET_SRC (temp1)) != REG
992 && GET_CODE (SET_SRC (temp1)) != SUBREG
993 && GET_CODE (SET_SRC (temp1)) != CONST_INT
994 && ! side_effects_p (SET_SRC (temp1))
995 && ! may_trap_p (SET_SRC (temp1))
996 && rtx_cost (SET_SRC (temp1), SET) < 10)
998 rtx new = gen_reg_rtx (GET_MODE (temp2));
1000 if (validate_change (temp, &SET_DEST (temp1), new, 0))
1002 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1003 emit_insn_after_with_line_notes (PATTERN (temp),
1004 PREV_INSN (insn), temp);
1006 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1010 /* Similarly, if it takes two insns to compute EXP but they
1011 have the same destination. Here TEMP3 will be the second
1012 insn and TEMP4 the SET from that insn. */
1014 if (! reload_completed
1015 && this_is_condjump && ! this_is_simplejump
1017 && (temp = next_nonnote_insn (insn)) != 0
1018 && GET_CODE (temp) == INSN
1019 && REG_NOTES (temp) == 0
1020 && (temp3 = next_nonnote_insn (temp)) != 0
1021 && GET_CODE (temp3) == INSN
1022 && REG_NOTES (temp3) == 0
1023 && (reallabelprev == temp3
1024 || ((temp2 = next_active_insn (temp3)) != 0
1025 && simplejump_p (temp2)
1026 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1027 && (temp1 = single_set (temp)) != 0
1028 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
1029 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1030 #ifdef SMALL_REGISTER_CLASSES
1031 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
1033 && ! side_effects_p (SET_SRC (temp1))
1034 && ! may_trap_p (SET_SRC (temp1))
1035 && rtx_cost (SET_SRC (temp1), SET) < 10
1036 && (temp4 = single_set (temp3)) != 0
1037 && rtx_equal_p (SET_DEST (temp4), temp2)
1038 && ! side_effects_p (SET_SRC (temp4))
1039 && ! may_trap_p (SET_SRC (temp4))
1040 && rtx_cost (SET_SRC (temp4), SET) < 10)
1042 rtx new = gen_reg_rtx (GET_MODE (temp2));
1044 if (validate_change (temp, &SET_DEST (temp1), new, 0))
1046 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1047 emit_insn_after_with_line_notes (PATTERN (temp),
1048 PREV_INSN (insn), temp);
1049 emit_insn_after_with_line_notes
1050 (replace_rtx (PATTERN (temp3), temp2, new),
1051 PREV_INSN (insn), temp3);
1053 delete_insn (temp3);
1054 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1058 /* Finally, handle the case where two insns are used to
1059 compute EXP but a temporary register is used. Here we must
1060 ensure that the temporary register is not used anywhere else. */
1062 if (! reload_completed
1064 && this_is_condjump && ! this_is_simplejump
1066 && (temp = next_nonnote_insn (insn)) != 0
1067 && GET_CODE (temp) == INSN
1068 && REG_NOTES (temp) == 0
1069 && (temp3 = next_nonnote_insn (temp)) != 0
1070 && GET_CODE (temp3) == INSN
1071 && REG_NOTES (temp3) == 0
1072 && (reallabelprev == temp3
1073 || ((temp2 = next_active_insn (temp3)) != 0
1074 && simplejump_p (temp2)
1075 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1076 && (temp1 = single_set (temp)) != 0
1077 && (temp5 = SET_DEST (temp1),
1078 (GET_CODE (temp5) == REG
1079 || (GET_CODE (temp5) == SUBREG
1080 && (temp5 = SUBREG_REG (temp5),
1081 GET_CODE (temp5) == REG))))
1082 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
1083 && regno_first_uid[REGNO (temp5)] == INSN_UID (temp)
1084 && regno_last_uid[REGNO (temp5)] == INSN_UID (temp3)
1085 && ! side_effects_p (SET_SRC (temp1))
1086 && ! may_trap_p (SET_SRC (temp1))
1087 && rtx_cost (SET_SRC (temp1), SET) < 10
1088 && (temp4 = single_set (temp3)) != 0
1089 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
1090 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1091 #ifdef SMALL_REGISTER_CLASSES
1092 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
1094 && rtx_equal_p (SET_DEST (temp4), temp2)
1095 && ! side_effects_p (SET_SRC (temp4))
1096 && ! may_trap_p (SET_SRC (temp4))
1097 && rtx_cost (SET_SRC (temp4), SET) < 10)
1099 rtx new = gen_reg_rtx (GET_MODE (temp2));
1101 if (validate_change (temp3, &SET_DEST (temp4), new, 0))
1103 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1104 emit_insn_after_with_line_notes (PATTERN (temp),
1105 PREV_INSN (insn), temp);
1106 emit_insn_after_with_line_notes (PATTERN (temp3),
1107 PREV_INSN (insn), temp3);
1109 delete_insn (temp3);
1110 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1113 #endif /* HAVE_cc0 */
1115 /* Try to use a conditional move (if the target has them), or a
1116 store-flag insn. The general case is:
1118 1) x = a; if (...) x = b; and
1121 If the jump would be faster, the machine should not have defined
1122 the movcc or scc insns!. These cases are often made by the
1123 previous optimization.
1125 The second case is treated as x = x; if (...) x = b;.
1127 INSN here is the jump around the store. We set:
1129 TEMP to the "x = b;" insn.
1132 TEMP3 to A (X in the second case).
1133 TEMP4 to the condition being tested.
1134 TEMP5 to the earliest insn used to find the condition. */
1136 if (/* We can't do this after reload has completed. */
1138 && this_is_condjump && ! this_is_simplejump
1139 /* Set TEMP to the "x = b;" insn. */
1140 && (temp = next_nonnote_insn (insn)) != 0
1141 && GET_CODE (temp) == INSN
1142 && GET_CODE (PATTERN (temp)) == SET
1143 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1144 #ifdef SMALL_REGISTER_CLASSES
1145 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
1147 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1148 || GET_CODE (temp2) == SUBREG
1149 /* ??? How about floating point constants? */
1150 || GET_CODE (temp2) == CONST_INT)
1151 /* Allow either form, but prefer the former if both apply.
1152 There is no point in using the old value of TEMP1 if
1153 it is a register, since cse will alias them. It can
1154 lose if the old value were a hard register since CSE
1155 won't replace hard registers. */
1156 && (((temp3 = reg_set_last (temp1, insn)) != 0)
1157 /* Make the latter case look like x = x; if (...) x = b; */
1158 || (temp3 = temp1, 1))
1159 /* INSN must either branch to the insn after TEMP or the insn
1160 after TEMP must branch to the same place as INSN. */
1161 && (reallabelprev == temp
1162 || ((temp4 = next_active_insn (temp)) != 0
1163 && simplejump_p (temp4)
1164 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1165 && (temp4 = get_condition (insn, &temp5)) != 0
1166 /* We must be comparing objects whose modes imply the size.
1167 We could handle BLKmode if (1) emit_store_flag could
1168 and (2) we could find the size reliably. */
1169 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1170 /* Even if branches are cheap, the store_flag optimization
1171 can win when the operation to be performed can be
1172 expressed directly. */
1174 /* If the previous insn sets CC0 and something else, we can't
1175 do this since we are going to delete that insn. */
1177 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1178 && GET_CODE (temp6) == INSN
1179 && (sets_cc0_p (PATTERN (temp6)) == -1
1180 || (sets_cc0_p (PATTERN (temp6)) == 1
1181 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1185 #ifdef HAVE_conditional_move
1186 /* First try a conditional move. */
1188 enum rtx_code code = GET_CODE (temp4);
1190 rtx cond0, cond1, aval, bval;
1193 /* Copy the compared variables into cond0 and cond1, so that
1194 any side effects performed in or after the old comparison,
1195 will not affect our compare which will come later. */
1196 /* ??? Is it possible to just use the comparison in the jump
1197 insn? After all, we're going to delete it. We'd have
1198 to modify emit_conditional_move to take a comparison rtx
1199 instead or write a new function. */
1200 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1201 /* We want the target to be able to simplify comparisons with
1202 zero (and maybe other constants as well), so don't create
1203 pseudos for them. There's no need to either. */
1204 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1205 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1206 cond1 = XEXP (temp4, 1);
1208 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1214 target = emit_conditional_move (var, code,
1215 cond0, cond1, VOIDmode,
1216 aval, bval, GET_MODE (var),
1217 (code == LTU || code == GEU
1218 || code == LEU || code == GTU));
1224 /* Save the conditional move sequence but don't emit it
1225 yet. On some machines, like the alpha, it is possible
1226 that temp5 == insn, so next generate the sequence that
1227 saves the compared values and then emit both
1228 sequences ensuring seq1 occurs before seq2. */
1229 seq2 = get_insns ();
1232 /* Now that we can't fail, generate the copy insns that
1233 preserve the compared values. */
1235 emit_move_insn (cond0, XEXP (temp4, 0));
1236 if (cond1 != XEXP (temp4, 1))
1237 emit_move_insn (cond1, XEXP (temp4, 1));
1238 seq1 = get_insns ();
1241 emit_insns_before (seq1, temp5);
1242 /* Insert conditional move after insn, to be sure that
1243 the jump and a possible compare won't be separated */
1244 emit_insns_after (seq2, insn);
1246 /* ??? We can also delete the insn that sets X to A.
1247 Flow will do it too though. */
1249 next = NEXT_INSN (insn);
1259 /* That didn't work, try a store-flag insn.
1261 We further divide the cases into:
1263 1) x = a; if (...) x = b; and either A or B is zero,
1264 2) if (...) x = 0; and jumps are expensive,
1265 3) x = a; if (...) x = b; and A and B are constants where all
1266 the set bits in A are also set in B and jumps are expensive,
1267 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1269 5) if (...) x = b; if jumps are even more expensive. */
1271 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1272 && ((GET_CODE (temp3) == CONST_INT)
1273 /* Make the latter case look like
1274 x = x; if (...) x = 0; */
1277 && temp2 == const0_rtx)
1278 || BRANCH_COST >= 3)))
1279 /* If B is zero, OK; if A is zero, can only do (1) if we
1280 can reverse the condition. See if (3) applies possibly
1281 by reversing the condition. Prefer reversing to (4) when
1282 branches are very expensive. */
1283 && (((BRANCH_COST >= 2
1284 || STORE_FLAG_VALUE == -1
1285 || (STORE_FLAG_VALUE == 1
1286 /* Check that the mask is a power of two,
1287 so that it can probably be generated
1289 && exact_log2 (INTVAL (temp3)) >= 0))
1290 && (reversep = 0, temp2 == const0_rtx))
1291 || ((BRANCH_COST >= 2
1292 || STORE_FLAG_VALUE == -1
1293 || (STORE_FLAG_VALUE == 1
1294 && exact_log2 (INTVAL (temp2)) >= 0))
1295 && temp3 == const0_rtx
1296 && (reversep = can_reverse_comparison_p (temp4, insn)))
1297 || (BRANCH_COST >= 2
1298 && GET_CODE (temp2) == CONST_INT
1299 && GET_CODE (temp3) == CONST_INT
1300 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1301 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1302 && (reversep = can_reverse_comparison_p (temp4,
1304 || BRANCH_COST >= 3)
1307 enum rtx_code code = GET_CODE (temp4);
1308 rtx uval, cval, var = temp1;
1312 /* If necessary, reverse the condition. */
1314 code = reverse_condition (code), uval = temp2, cval = temp3;
1316 uval = temp3, cval = temp2;
1318 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1319 is the constant 1, it is best to just compute the result
1320 directly. If UVAL is constant and STORE_FLAG_VALUE
1321 includes all of its bits, it is best to compute the flag
1322 value unnormalized and `and' it with UVAL. Otherwise,
1323 normalize to -1 and `and' with UVAL. */
1324 normalizep = (cval != const0_rtx ? -1
1325 : (uval == const1_rtx ? 1
1326 : (GET_CODE (uval) == CONST_INT
1327 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1330 /* We will be putting the store-flag insn immediately in
1331 front of the comparison that was originally being done,
1332 so we know all the variables in TEMP4 will be valid.
1333 However, this might be in front of the assignment of
1334 A to VAR. If it is, it would clobber the store-flag
1335 we will be emitting.
1337 Therefore, emit into a temporary which will be copied to
1338 VAR immediately after TEMP. */
1341 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1342 XEXP (temp4, 0), XEXP (temp4, 1),
1344 (code == LTU || code == LEU
1345 || code == GEU || code == GTU),
1355 /* Put the store-flag insns in front of the first insn
1356 used to compute the condition to ensure that we
1357 use the same values of them as the current
1358 comparison. However, the remainder of the insns we
1359 generate will be placed directly in front of the
1360 jump insn, in case any of the pseudos we use
1361 are modified earlier. */
1363 emit_insns_before (seq, temp5);
1367 /* Both CVAL and UVAL are non-zero. */
1368 if (cval != const0_rtx && uval != const0_rtx)
1372 tem1 = expand_and (uval, target, NULL_RTX);
1373 if (GET_CODE (cval) == CONST_INT
1374 && GET_CODE (uval) == CONST_INT
1375 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1379 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1380 target, NULL_RTX, 0);
1381 tem2 = expand_and (cval, tem2,
1382 (GET_CODE (tem2) == REG
1386 /* If we usually make new pseudos, do so here. This
1387 turns out to help machines that have conditional
1389 /* ??? Conditional moves have already been handled.
1390 This may be obsolete. */
1392 if (flag_expensive_optimizations)
1395 target = expand_binop (GET_MODE (var), ior_optab,
1399 else if (normalizep != 1)
1401 /* We know that either CVAL or UVAL is zero. If
1402 UVAL is zero, negate TARGET and `and' with CVAL.
1403 Otherwise, `and' with UVAL. */
1404 if (uval == const0_rtx)
1406 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1407 target, NULL_RTX, 0);
1411 target = expand_and (uval, target,
1412 (GET_CODE (target) == REG
1413 && ! preserve_subexpressions_p ()
1414 ? target : NULL_RTX));
1417 emit_move_insn (var, target);
1421 /* If INSN uses CC0, we must not separate it from the
1422 insn that sets cc0. */
1423 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1424 before = prev_nonnote_insn (before);
1426 emit_insns_before (seq, before);
1429 next = NEXT_INSN (insn);
1439 /* If branches are expensive, convert
1440 if (foo) bar++; to bar += (foo != 0);
1441 and similarly for "bar--;"
1443 INSN is the conditional branch around the arithmetic. We set:
1445 TEMP is the arithmetic insn.
1446 TEMP1 is the SET doing the arithmetic.
1447 TEMP2 is the operand being incremented or decremented.
1448 TEMP3 to the condition being tested.
1449 TEMP4 to the earliest insn used to find the condition. */
1451 if ((BRANCH_COST >= 2
1459 && ! reload_completed
1460 && this_is_condjump && ! this_is_simplejump
1461 && (temp = next_nonnote_insn (insn)) != 0
1462 && (temp1 = single_set (temp)) != 0
1463 && (temp2 = SET_DEST (temp1),
1464 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1465 && GET_CODE (SET_SRC (temp1)) == PLUS
1466 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1467 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1468 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1469 && ! side_effects_p (temp2)
1470 && ! may_trap_p (temp2)
1471 /* INSN must either branch to the insn after TEMP or the insn
1472 after TEMP must branch to the same place as INSN. */
1473 && (reallabelprev == temp
1474 || ((temp3 = next_active_insn (temp)) != 0
1475 && simplejump_p (temp3)
1476 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1477 && (temp3 = get_condition (insn, &temp4)) != 0
1478 /* We must be comparing objects whose modes imply the size.
1479 We could handle BLKmode if (1) emit_store_flag could
1480 and (2) we could find the size reliably. */
1481 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1482 && can_reverse_comparison_p (temp3, insn))
1484 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1485 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1489 /* It must be the case that TEMP2 is not modified in the range
1490 [TEMP4, INSN). The one exception we make is if the insn
1491 before INSN sets TEMP2 to something which is also unchanged
1492 in that range. In that case, we can move the initialization
1493 into our sequence. */
1495 if ((temp5 = prev_active_insn (insn)) != 0
1496 && GET_CODE (temp5) == INSN
1497 && (temp6 = single_set (temp5)) != 0
1498 && rtx_equal_p (temp2, SET_DEST (temp6))
1499 && (CONSTANT_P (SET_SRC (temp6))
1500 || GET_CODE (SET_SRC (temp6)) == REG
1501 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1503 emit_insn (PATTERN (temp5));
1505 init = SET_SRC (temp6);
1508 if (CONSTANT_P (init)
1509 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1510 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1511 XEXP (temp3, 0), XEXP (temp3, 1),
1513 (code == LTU || code == LEU
1514 || code == GTU || code == GEU), 1);
1516 /* If we can do the store-flag, do the addition or
1520 target = expand_binop (GET_MODE (temp2),
1521 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1522 ? add_optab : sub_optab),
1523 temp2, target, temp2, 0, OPTAB_WIDEN);
1527 /* Put the result back in temp2 in case it isn't already.
1528 Then replace the jump, possible a CC0-setting insn in
1529 front of the jump, and TEMP, with the sequence we have
1532 if (target != temp2)
1533 emit_move_insn (temp2, target);
1538 emit_insns_before (seq, temp4);
1542 delete_insn (init_insn);
1544 next = NEXT_INSN (insn);
1546 delete_insn (prev_nonnote_insn (insn));
1556 /* Simplify if (...) x = 1; else {...} if (x) ...
1557 We recognize this case scanning backwards as well.
1559 TEMP is the assignment to x;
1560 TEMP1 is the label at the head of the second if. */
1561 /* ?? This should call get_condition to find the values being
1562 compared, instead of looking for a COMPARE insn when HAVE_cc0
1563 is not defined. This would allow it to work on the m88k. */
1564 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1565 is not defined and the condition is tested by a separate compare
1566 insn. This is because the code below assumes that the result
1567 of the compare dies in the following branch.
1569 Not only that, but there might be other insns between the
1570 compare and branch whose results are live. Those insns need
1573 A way to fix this is to move the insns at JUMP_LABEL (insn)
1574 to before INSN. If we are running before flow, they will
1575 be deleted if they aren't needed. But this doesn't work
1578 This is really a special-case of jump threading, anyway. The
1579 right thing to do is to replace this and jump threading with
1580 much simpler code in cse.
1582 This code has been turned off in the non-cc0 case in the
1586 else if (this_is_simplejump
1587 /* Safe to skip USE and CLOBBER insns here
1588 since they will not be deleted. */
1589 && (temp = prev_active_insn (insn))
1590 && no_labels_between_p (temp, insn)
1591 && GET_CODE (temp) == INSN
1592 && GET_CODE (PATTERN (temp)) == SET
1593 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1594 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1595 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1596 /* If we find that the next value tested is `x'
1597 (TEMP1 is the insn where this happens), win. */
1598 && GET_CODE (temp1) == INSN
1599 && GET_CODE (PATTERN (temp1)) == SET
1601 /* Does temp1 `tst' the value of x? */
1602 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1603 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1604 && (temp1 = next_nonnote_insn (temp1))
1606 /* Does temp1 compare the value of x against zero? */
1607 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1608 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1609 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1610 == SET_DEST (PATTERN (temp)))
1611 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1612 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1614 && condjump_p (temp1))
1616 /* Get the if_then_else from the condjump. */
1617 rtx choice = SET_SRC (PATTERN (temp1));
1618 if (GET_CODE (choice) == IF_THEN_ELSE)
1620 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1621 rtx val = SET_SRC (PATTERN (temp));
1623 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1627 if (cond == const_true_rtx)
1628 ultimate = XEXP (choice, 1);
1629 else if (cond == const0_rtx)
1630 ultimate = XEXP (choice, 2);
1634 if (ultimate == pc_rtx)
1635 ultimate = get_label_after (temp1);
1636 else if (ultimate && GET_CODE (ultimate) != RETURN)
1637 ultimate = XEXP (ultimate, 0);
1639 if (ultimate && JUMP_LABEL(insn) != ultimate)
1640 changed |= redirect_jump (insn, ultimate);
1646 /* @@ This needs a bit of work before it will be right.
1648 Any type of comparison can be accepted for the first and
1649 second compare. When rewriting the first jump, we must
1650 compute the what conditions can reach label3, and use the
1651 appropriate code. We can not simply reverse/swap the code
1652 of the first jump. In some cases, the second jump must be
1656 < == converts to > ==
1657 < != converts to == >
1660 If the code is written to only accept an '==' test for the second
1661 compare, then all that needs to be done is to swap the condition
1662 of the first branch.
1664 It is questionable whether we want this optimization anyways,
1665 since if the user wrote code like this because he/she knew that
1666 the jump to label1 is taken most of the time, then rewriting
1667 this gives slower code. */
1668 /* @@ This should call get_condition to find the values being
1669 compared, instead of looking for a COMPARE insn when HAVE_cc0
1670 is not defined. This would allow it to work on the m88k. */
1671 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1672 is not defined and the condition is tested by a separate compare
1673 insn. This is because the code below assumes that the result
1674 of the compare dies in the following branch. */
1676 /* Simplify test a ~= b
1690 where ~= is an inequality, e.g. >, and ~~= is the swapped
1693 We recognize this case scanning backwards.
1695 TEMP is the conditional jump to `label2';
1696 TEMP1 is the test for `a == b';
1697 TEMP2 is the conditional jump to `label1';
1698 TEMP3 is the test for `a ~= b'. */
1699 else if (this_is_simplejump
1700 && (temp = prev_active_insn (insn))
1701 && no_labels_between_p (temp, insn)
1702 && condjump_p (temp)
1703 && (temp1 = prev_active_insn (temp))
1704 && no_labels_between_p (temp1, temp)
1705 && GET_CODE (temp1) == INSN
1706 && GET_CODE (PATTERN (temp1)) == SET
1708 && sets_cc0_p (PATTERN (temp1)) == 1
1710 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1711 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1712 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1714 && (temp2 = prev_active_insn (temp1))
1715 && no_labels_between_p (temp2, temp1)
1716 && condjump_p (temp2)
1717 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1718 && (temp3 = prev_active_insn (temp2))
1719 && no_labels_between_p (temp3, temp2)
1720 && GET_CODE (PATTERN (temp3)) == SET
1721 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1722 SET_DEST (PATTERN (temp1)))
1723 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1724 SET_SRC (PATTERN (temp3)))
1725 && ! inequality_comparisons_p (PATTERN (temp))
1726 && inequality_comparisons_p (PATTERN (temp2)))
1728 rtx fallthrough_label = JUMP_LABEL (temp2);
1730 ++LABEL_NUSES (fallthrough_label);
1731 if (swap_jump (temp2, JUMP_LABEL (insn)))
1737 if (--LABEL_NUSES (fallthrough_label) == 0)
1738 delete_insn (fallthrough_label);
1741 /* Simplify if (...) {... x = 1;} if (x) ...
1743 We recognize this case backwards.
1745 TEMP is the test of `x';
1746 TEMP1 is the assignment to `x' at the end of the
1747 previous statement. */
1748 /* @@ This should call get_condition to find the values being
1749 compared, instead of looking for a COMPARE insn when HAVE_cc0
1750 is not defined. This would allow it to work on the m88k. */
1751 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1752 is not defined and the condition is tested by a separate compare
1753 insn. This is because the code below assumes that the result
1754 of the compare dies in the following branch. */
1756 /* ??? This has to be turned off. The problem is that the
1757 unconditional jump might indirectly end up branching to the
1758 label between TEMP1 and TEMP. We can't detect this, in general,
1759 since it may become a jump to there after further optimizations.
1760 If that jump is done, it will be deleted, so we will retry
1761 this optimization in the next pass, thus an infinite loop.
1763 The present code prevents this by putting the jump after the
1764 label, but this is not logically correct. */
1766 else if (this_is_condjump
1767 /* Safe to skip USE and CLOBBER insns here
1768 since they will not be deleted. */
1769 && (temp = prev_active_insn (insn))
1770 && no_labels_between_p (temp, insn)
1771 && GET_CODE (temp) == INSN
1772 && GET_CODE (PATTERN (temp)) == SET
1774 && sets_cc0_p (PATTERN (temp)) == 1
1775 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1777 /* Temp must be a compare insn, we can not accept a register
1778 to register move here, since it may not be simply a
1780 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1781 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1782 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1783 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1784 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1786 /* May skip USE or CLOBBER insns here
1787 for checking for opportunity, since we
1788 take care of them later. */
1789 && (temp1 = prev_active_insn (temp))
1790 && GET_CODE (temp1) == INSN
1791 && GET_CODE (PATTERN (temp1)) == SET
1793 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1795 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1796 == SET_DEST (PATTERN (temp1)))
1798 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1799 /* If this isn't true, cse will do the job. */
1800 && ! no_labels_between_p (temp1, temp))
1802 /* Get the if_then_else from the condjump. */
1803 rtx choice = SET_SRC (PATTERN (insn));
1804 if (GET_CODE (choice) == IF_THEN_ELSE
1805 && (GET_CODE (XEXP (choice, 0)) == EQ
1806 || GET_CODE (XEXP (choice, 0)) == NE))
1808 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1813 /* Get the place that condjump will jump to
1814 if it is reached from here. */
1815 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1817 ultimate = XEXP (choice, 1);
1819 ultimate = XEXP (choice, 2);
1820 /* Get it as a CODE_LABEL. */
1821 if (ultimate == pc_rtx)
1822 ultimate = get_label_after (insn);
1824 /* Get the label out of the LABEL_REF. */
1825 ultimate = XEXP (ultimate, 0);
1827 /* Insert the jump immediately before TEMP, specifically
1828 after the label that is between TEMP1 and TEMP. */
1829 last_insn = PREV_INSN (temp);
1831 /* If we would be branching to the next insn, the jump
1832 would immediately be deleted and the re-inserted in
1833 a subsequent pass over the code. So don't do anything
1835 if (next_active_insn (last_insn)
1836 != next_active_insn (ultimate))
1838 emit_barrier_after (last_insn);
1839 p = emit_jump_insn_after (gen_jump (ultimate),
1841 JUMP_LABEL (p) = ultimate;
1842 ++LABEL_NUSES (ultimate);
1843 if (INSN_UID (ultimate) < max_jump_chain
1844 && INSN_CODE (p) < max_jump_chain)
1846 jump_chain[INSN_UID (p)]
1847 = jump_chain[INSN_UID (ultimate)];
1848 jump_chain[INSN_UID (ultimate)] = p;
1856 /* Detect a conditional jump going to the same place
1857 as an immediately following unconditional jump. */
1858 else if (this_is_condjump
1859 && (temp = next_active_insn (insn)) != 0
1860 && simplejump_p (temp)
1861 && (next_active_insn (JUMP_LABEL (insn))
1862 == next_active_insn (JUMP_LABEL (temp))))
1868 /* Detect a conditional jump jumping over an unconditional jump. */
1870 else if ((this_is_condjump || this_is_condjump_in_parallel)
1871 && ! this_is_simplejump
1872 && reallabelprev != 0
1873 && GET_CODE (reallabelprev) == JUMP_INSN
1874 && prev_active_insn (reallabelprev) == insn
1875 && no_labels_between_p (insn, reallabelprev)
1876 && simplejump_p (reallabelprev))
1878 /* When we invert the unconditional jump, we will be
1879 decrementing the usage count of its old label.
1880 Make sure that we don't delete it now because that
1881 might cause the following code to be deleted. */
1882 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1883 rtx prev_label = JUMP_LABEL (insn);
1886 ++LABEL_NUSES (prev_label);
1888 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1890 /* It is very likely that if there are USE insns before
1891 this jump, they hold REG_DEAD notes. These REG_DEAD
1892 notes are no longer valid due to this optimization,
1893 and will cause the life-analysis that following passes
1894 (notably delayed-branch scheduling) to think that
1895 these registers are dead when they are not.
1897 To prevent this trouble, we just remove the USE insns
1898 from the insn chain. */
1900 while (prev_uses && GET_CODE (prev_uses) == INSN
1901 && GET_CODE (PATTERN (prev_uses)) == USE)
1903 rtx useless = prev_uses;
1904 prev_uses = prev_nonnote_insn (prev_uses);
1905 delete_insn (useless);
1908 delete_insn (reallabelprev);
1913 /* We can now safely delete the label if it is unreferenced
1914 since the delete_insn above has deleted the BARRIER. */
1915 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1916 delete_insn (prev_label);
1921 /* Detect a jump to a jump. */
1923 nlabel = follow_jumps (JUMP_LABEL (insn));
1924 if (nlabel != JUMP_LABEL (insn)
1925 && redirect_jump (insn, nlabel))
1931 /* Look for if (foo) bar; else break; */
1932 /* The insns look like this:
1933 insn = condjump label1;
1934 ...range1 (some insns)...
1937 ...range2 (some insns)...
1938 jump somewhere unconditionally
1941 rtx label1 = next_label (insn);
1942 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1943 /* Don't do this optimization on the first round, so that
1944 jump-around-a-jump gets simplified before we ask here
1945 whether a jump is unconditional.
1947 Also don't do it when we are called after reload since
1948 it will confuse reorg. */
1950 && (reload_completed ? ! flag_delayed_branch : 1)
1951 /* Make sure INSN is something we can invert. */
1952 && condjump_p (insn)
1954 && JUMP_LABEL (insn) == label1
1955 && LABEL_NUSES (label1) == 1
1956 && GET_CODE (range1end) == JUMP_INSN
1957 && simplejump_p (range1end))
1959 rtx label2 = next_label (label1);
1960 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1961 if (range1end != range2end
1962 && JUMP_LABEL (range1end) == label2
1963 && GET_CODE (range2end) == JUMP_INSN
1964 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1965 /* Invert the jump condition, so we
1966 still execute the same insns in each case. */
1967 && invert_jump (insn, label1))
1969 rtx range1beg = next_active_insn (insn);
1970 rtx range2beg = next_active_insn (label1);
1971 rtx range1after, range2after;
1972 rtx range1before, range2before;
1975 /* Include in each range any notes before it, to be
1976 sure that we get the line number note if any, even
1977 if there are other notes here. */
1978 while (PREV_INSN (range1beg)
1979 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1980 range1beg = PREV_INSN (range1beg);
1982 while (PREV_INSN (range2beg)
1983 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1984 range2beg = PREV_INSN (range2beg);
1986 /* Don't move NOTEs for blocks or loops; shift them
1987 outside the ranges, where they'll stay put. */
1988 range1beg = squeeze_notes (range1beg, range1end);
1989 range2beg = squeeze_notes (range2beg, range2end);
1991 /* Get current surrounds of the 2 ranges. */
1992 range1before = PREV_INSN (range1beg);
1993 range2before = PREV_INSN (range2beg);
1994 range1after = NEXT_INSN (range1end);
1995 range2after = NEXT_INSN (range2end);
1997 /* Splice range2 where range1 was. */
1998 NEXT_INSN (range1before) = range2beg;
1999 PREV_INSN (range2beg) = range1before;
2000 NEXT_INSN (range2end) = range1after;
2001 PREV_INSN (range1after) = range2end;
2002 /* Splice range1 where range2 was. */
2003 NEXT_INSN (range2before) = range1beg;
2004 PREV_INSN (range1beg) = range2before;
2005 NEXT_INSN (range1end) = range2after;
2006 PREV_INSN (range2after) = range1end;
2008 /* Check for a loop end note between the end of
2009 range2, and the next code label. If there is one,
2010 then what we have really seen is
2011 if (foo) break; end_of_loop;
2012 and moved the break sequence outside the loop.
2013 We must move the LOOP_END note to where the
2014 loop really ends now, or we will confuse loop
2015 optimization. Stop if we find a LOOP_BEG note
2016 first, since we don't want to move the LOOP_END
2017 note in that case. */
2018 for (;range2after != label2; range2after = rangenext)
2020 rangenext = NEXT_INSN (range2after);
2021 if (GET_CODE (range2after) == NOTE)
2023 if (NOTE_LINE_NUMBER (range2after)
2024 == NOTE_INSN_LOOP_END)
2026 NEXT_INSN (PREV_INSN (range2after))
2028 PREV_INSN (rangenext)
2029 = PREV_INSN (range2after);
2030 PREV_INSN (range2after)
2031 = PREV_INSN (range1beg);
2032 NEXT_INSN (range2after) = range1beg;
2033 NEXT_INSN (PREV_INSN (range1beg))
2035 PREV_INSN (range1beg) = range2after;
2037 else if (NOTE_LINE_NUMBER (range2after)
2038 == NOTE_INSN_LOOP_BEG)
2048 /* Now that the jump has been tensioned,
2049 try cross jumping: check for identical code
2050 before the jump and before its target label. */
2052 /* First, cross jumping of conditional jumps: */
2054 if (cross_jump && condjump_p (insn))
2056 rtx newjpos, newlpos;
2057 rtx x = prev_real_insn (JUMP_LABEL (insn));
2059 /* A conditional jump may be crossjumped
2060 only if the place it jumps to follows
2061 an opposing jump that comes back here. */
2063 if (x != 0 && ! jump_back_p (x, insn))
2064 /* We have no opposing jump;
2065 cannot cross jump this insn. */
2069 /* TARGET is nonzero if it is ok to cross jump
2070 to code before TARGET. If so, see if matches. */
2072 find_cross_jump (insn, x, 2,
2073 &newjpos, &newlpos);
2077 do_cross_jump (insn, newjpos, newlpos);
2078 /* Make the old conditional jump
2079 into an unconditional one. */
2080 SET_SRC (PATTERN (insn))
2081 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
2082 INSN_CODE (insn) = -1;
2083 emit_barrier_after (insn);
2084 /* Add to jump_chain unless this is a new label
2085 whose UID is too large. */
2086 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
2088 jump_chain[INSN_UID (insn)]
2089 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2090 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2097 /* Cross jumping of unconditional jumps:
2098 a few differences. */
2100 if (cross_jump && simplejump_p (insn))
2102 rtx newjpos, newlpos;
2107 /* TARGET is nonzero if it is ok to cross jump
2108 to code before TARGET. If so, see if matches. */
2109 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2110 &newjpos, &newlpos);
2112 /* If cannot cross jump to code before the label,
2113 see if we can cross jump to another jump to
2115 /* Try each other jump to this label. */
2116 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2117 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2118 target != 0 && newjpos == 0;
2119 target = jump_chain[INSN_UID (target)])
2121 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2122 /* Ignore TARGET if it's deleted. */
2123 && ! INSN_DELETED_P (target))
2124 find_cross_jump (insn, target, 2,
2125 &newjpos, &newlpos);
2129 do_cross_jump (insn, newjpos, newlpos);
2135 /* This code was dead in the previous jump.c! */
2136 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2138 /* Return insns all "jump to the same place"
2139 so we can cross-jump between any two of them. */
2141 rtx newjpos, newlpos, target;
2145 /* If cannot cross jump to code before the label,
2146 see if we can cross jump to another jump to
2148 /* Try each other jump to this label. */
2149 for (target = jump_chain[0];
2150 target != 0 && newjpos == 0;
2151 target = jump_chain[INSN_UID (target)])
2153 && ! INSN_DELETED_P (target)
2154 && GET_CODE (PATTERN (target)) == RETURN)
2155 find_cross_jump (insn, target, 2,
2156 &newjpos, &newlpos);
2160 do_cross_jump (insn, newjpos, newlpos);
2171 /* Delete extraneous line number notes.
2172 Note that two consecutive notes for different lines are not really
2173 extraneous. There should be some indication where that line belonged,
2174 even if it became empty. */
2179 for (insn = f; insn; insn = NEXT_INSN (insn))
2180 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2182 /* Delete this note if it is identical to previous note. */
2184 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2185 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2198 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2199 in front of it. If the machine allows it at this point (we might be
2200 after reload for a leaf routine), it will improve optimization for it
2201 to be there. We do this both here and at the start of this pass since
2202 the RETURN might have been deleted by some of our optimizations. */
2203 insn = get_last_insn ();
2204 while (insn && GET_CODE (insn) == NOTE)
2205 insn = PREV_INSN (insn);
2207 if (insn && GET_CODE (insn) != BARRIER)
2209 emit_jump_insn (gen_return ());
2215 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2216 If so, delete it, and record that this function can drop off the end. */
2222 /* One label can follow the end-note: the return label. */
2223 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2224 /* Ordinary insns can follow it if returning a structure. */
2225 || GET_CODE (insn) == INSN
2226 /* If machine uses explicit RETURN insns, no epilogue,
2227 then one of them follows the note. */
2228 || (GET_CODE (insn) == JUMP_INSN
2229 && GET_CODE (PATTERN (insn)) == RETURN)
2230 /* A barrier can follow the return insn. */
2231 || GET_CODE (insn) == BARRIER
2232 /* Other kinds of notes can follow also. */
2233 || (GET_CODE (insn) == NOTE
2234 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2235 insn = PREV_INSN (insn);
2238 /* Report if control can fall through at the end of the function. */
2239 if (insn && GET_CODE (insn) == NOTE
2240 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2246 /* Show JUMP_CHAIN no longer valid. */
2250 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2251 jump. Assume that this unconditional jump is to the exit test code. If
2252 the code is sufficiently simple, make a copy of it before INSN,
2253 followed by a jump to the exit of the loop. Then delete the unconditional
2256 Return 1 if we made the change, else 0.
2258 This is only safe immediately after a regscan pass because it uses the
2259 values of regno_first_uid and regno_last_uid. */
2262 duplicate_loop_exit_test (loop_start)
2265 rtx insn, set, reg, p, link;
2268 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2270 int max_reg = max_reg_num ();
2273 /* Scan the exit code. We do not perform this optimization if any insn:
2277 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2278 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2279 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2282 Also, don't do this if the exit code is more than 20 insns. */
2284 for (insn = exitcode;
2286 && ! (GET_CODE (insn) == NOTE
2287 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2288 insn = NEXT_INSN (insn))
2290 switch (GET_CODE (insn))
2296 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2297 a jump immediately after the loop start that branches outside
2298 the loop but within an outer loop, near the exit test.
2299 If we copied this exit test and created a phony
2300 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2301 before the exit test look like these could be safely moved
2302 out of the loop even if they actually may be never executed.
2303 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2305 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2306 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2307 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2308 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2313 if (++num_insns > 20
2314 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2315 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2321 /* Unless INSN is zero, we can do the optimization. */
2327 /* See if any insn sets a register only used in the loop exit code and
2328 not a user variable. If so, replace it with a new register. */
2329 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2330 if (GET_CODE (insn) == INSN
2331 && (set = single_set (insn)) != 0
2332 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2333 || (GET_CODE (reg) == SUBREG
2334 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2335 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2336 && regno_first_uid[REGNO (reg)] == INSN_UID (insn))
2338 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2339 if (regno_last_uid[REGNO (reg)] == INSN_UID (p))
2344 /* We can do the replacement. Allocate reg_map if this is the
2345 first replacement we found. */
2348 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2349 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2352 REG_LOOP_TEST_P (reg) = 1;
2354 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2358 /* Now copy each insn. */
2359 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2360 switch (GET_CODE (insn))
2363 copy = emit_barrier_before (loop_start);
2366 /* Only copy line-number notes. */
2367 if (NOTE_LINE_NUMBER (insn) >= 0)
2369 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2370 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2375 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2377 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2379 mark_jump_label (PATTERN (copy), copy, 0);
2381 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2383 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2384 if (REG_NOTE_KIND (link) != REG_LABEL)
2386 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
2387 XEXP (link, 0), REG_NOTES (copy)));
2388 if (reg_map && REG_NOTES (copy))
2389 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2393 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2395 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2396 mark_jump_label (PATTERN (copy), copy, 0);
2397 if (REG_NOTES (insn))
2399 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2401 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2404 /* If this is a simple jump, add it to the jump chain. */
2406 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2407 && simplejump_p (copy))
2409 jump_chain[INSN_UID (copy)]
2410 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2411 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2419 /* Now clean up by emitting a jump to the end label and deleting the jump
2420 at the start of the loop. */
2421 if (! copy || GET_CODE (copy) != BARRIER)
2423 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2425 mark_jump_label (PATTERN (copy), copy, 0);
2426 if (INSN_UID (copy) < max_jump_chain
2427 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2429 jump_chain[INSN_UID (copy)]
2430 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2431 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2433 emit_barrier_before (loop_start);
2436 /* Mark the exit code as the virtual top of the converted loop. */
2437 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2439 delete_insn (next_nonnote_insn (loop_start));
2444 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2445 loop-end notes between START and END out before START. Assume that
2446 END is not such a note. START may be such a note. Returns the value
2447 of the new starting insn, which may be different if the original start
2451 squeeze_notes (start, end)
2457 for (insn = start; insn != end; insn = next)
2459 next = NEXT_INSN (insn);
2460 if (GET_CODE (insn) == NOTE
2461 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2462 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2463 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2464 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2465 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2466 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2472 rtx prev = PREV_INSN (insn);
2473 PREV_INSN (insn) = PREV_INSN (start);
2474 NEXT_INSN (insn) = start;
2475 NEXT_INSN (PREV_INSN (insn)) = insn;
2476 PREV_INSN (NEXT_INSN (insn)) = insn;
2477 NEXT_INSN (prev) = next;
2478 PREV_INSN (next) = prev;
2486 /* Compare the instructions before insn E1 with those before E2
2487 to find an opportunity for cross jumping.
2488 (This means detecting identical sequences of insns followed by
2489 jumps to the same place, or followed by a label and a jump
2490 to that label, and replacing one with a jump to the other.)
2492 Assume E1 is a jump that jumps to label E2
2493 (that is not always true but it might as well be).
2494 Find the longest possible equivalent sequences
2495 and store the first insns of those sequences into *F1 and *F2.
2496 Store zero there if no equivalent preceding instructions are found.
2498 We give up if we find a label in stream 1.
2499 Actually we could transfer that label into stream 2. */
2502 find_cross_jump (e1, e2, minimum, f1, f2)
2507 register rtx i1 = e1, i2 = e2;
2508 register rtx p1, p2;
2511 rtx last1 = 0, last2 = 0;
2512 rtx afterlast1 = 0, afterlast2 = 0;
2520 i1 = prev_nonnote_insn (i1);
2522 i2 = PREV_INSN (i2);
2523 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2524 i2 = PREV_INSN (i2);
2529 /* Don't allow the range of insns preceding E1 or E2
2530 to include the other (E2 or E1). */
2531 if (i2 == e1 || i1 == e2)
2534 /* If we will get to this code by jumping, those jumps will be
2535 tensioned to go directly to the new label (before I2),
2536 so this cross-jumping won't cost extra. So reduce the minimum. */
2537 if (GET_CODE (i1) == CODE_LABEL)
2543 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2549 /* If this is a CALL_INSN, compare register usage information.
2550 If we don't check this on stack register machines, the two
2551 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2552 numbers of stack registers in the same basic block.
2553 If we don't check this on machines with delay slots, a delay slot may
2554 be filled that clobbers a parameter expected by the subroutine.
2556 ??? We take the simple route for now and assume that if they're
2557 equal, they were constructed identically. */
2559 if (GET_CODE (i1) == CALL_INSN
2560 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2561 CALL_INSN_FUNCTION_USAGE (i2)))
2565 /* If cross_jump_death_matters is not 0, the insn's mode
2566 indicates whether or not the insn contains any stack-like
2569 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2571 /* If register stack conversion has already been done, then
2572 death notes must also be compared before it is certain that
2573 the two instruction streams match. */
2576 HARD_REG_SET i1_regset, i2_regset;
2578 CLEAR_HARD_REG_SET (i1_regset);
2579 CLEAR_HARD_REG_SET (i2_regset);
2581 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2582 if (REG_NOTE_KIND (note) == REG_DEAD
2583 && STACK_REG_P (XEXP (note, 0)))
2584 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2586 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2587 if (REG_NOTE_KIND (note) == REG_DEAD
2588 && STACK_REG_P (XEXP (note, 0)))
2589 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2591 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2600 if (lose || GET_CODE (p1) != GET_CODE (p2)
2601 || ! rtx_renumbered_equal_p (p1, p2))
2603 /* The following code helps take care of G++ cleanups. */
2607 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2608 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2609 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2610 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2611 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2612 /* If the equivalences are not to a constant, they may
2613 reference pseudos that no longer exist, so we can't
2615 && CONSTANT_P (XEXP (equiv1, 0))
2616 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2618 rtx s1 = single_set (i1);
2619 rtx s2 = single_set (i2);
2620 if (s1 != 0 && s2 != 0
2621 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2623 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2624 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2625 if (! rtx_renumbered_equal_p (p1, p2))
2627 else if (apply_change_group ())
2632 /* Insns fail to match; cross jumping is limited to the following
2636 /* Don't allow the insn after a compare to be shared by
2637 cross-jumping unless the compare is also shared.
2638 Here, if either of these non-matching insns is a compare,
2639 exclude the following insn from possible cross-jumping. */
2640 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2641 last1 = afterlast1, last2 = afterlast2, ++minimum;
2644 /* If cross-jumping here will feed a jump-around-jump
2645 optimization, this jump won't cost extra, so reduce
2647 if (GET_CODE (i1) == JUMP_INSN
2649 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2655 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2657 /* Ok, this insn is potentially includable in a cross-jump here. */
2658 afterlast1 = last1, afterlast2 = last2;
2659 last1 = i1, last2 = i2, --minimum;
2663 if (minimum <= 0 && last1 != 0 && last1 != e1)
2664 *f1 = last1, *f2 = last2;
2668 do_cross_jump (insn, newjpos, newlpos)
2669 rtx insn, newjpos, newlpos;
2671 /* Find an existing label at this point
2672 or make a new one if there is none. */
2673 register rtx label = get_label_before (newlpos);
2675 /* Make the same jump insn jump to the new point. */
2676 if (GET_CODE (PATTERN (insn)) == RETURN)
2678 /* Remove from jump chain of returns. */
2679 delete_from_jump_chain (insn);
2680 /* Change the insn. */
2681 PATTERN (insn) = gen_jump (label);
2682 INSN_CODE (insn) = -1;
2683 JUMP_LABEL (insn) = label;
2684 LABEL_NUSES (label)++;
2685 /* Add to new the jump chain. */
2686 if (INSN_UID (label) < max_jump_chain
2687 && INSN_UID (insn) < max_jump_chain)
2689 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2690 jump_chain[INSN_UID (label)] = insn;
2694 redirect_jump (insn, label);
2696 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2697 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2698 the NEWJPOS stream. */
2700 while (newjpos != insn)
2704 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2705 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2706 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2707 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2708 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2709 remove_note (newlpos, lnote);
2711 delete_insn (newjpos);
2712 newjpos = next_real_insn (newjpos);
2713 newlpos = next_real_insn (newlpos);
2717 /* Return the label before INSN, or put a new label there. */
2720 get_label_before (insn)
2725 /* Find an existing label at this point
2726 or make a new one if there is none. */
2727 label = prev_nonnote_insn (insn);
2729 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2731 rtx prev = PREV_INSN (insn);
2733 label = gen_label_rtx ();
2734 emit_label_after (label, prev);
2735 LABEL_NUSES (label) = 0;
2740 /* Return the label after INSN, or put a new label there. */
2743 get_label_after (insn)
2748 /* Find an existing label at this point
2749 or make a new one if there is none. */
2750 label = next_nonnote_insn (insn);
2752 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2754 label = gen_label_rtx ();
2755 emit_label_after (label, insn);
2756 LABEL_NUSES (label) = 0;
2761 /* Return 1 if INSN is a jump that jumps to right after TARGET
2762 only on the condition that TARGET itself would drop through.
2763 Assumes that TARGET is a conditional jump. */
2766 jump_back_p (insn, target)
2770 enum rtx_code codei, codet;
2772 if (simplejump_p (insn) || ! condjump_p (insn)
2773 || simplejump_p (target)
2774 || target != prev_real_insn (JUMP_LABEL (insn)))
2777 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2778 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2780 codei = GET_CODE (cinsn);
2781 codet = GET_CODE (ctarget);
2783 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2785 if (! can_reverse_comparison_p (cinsn, insn))
2787 codei = reverse_condition (codei);
2790 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2792 if (! can_reverse_comparison_p (ctarget, target))
2794 codet = reverse_condition (codet);
2797 return (codei == codet
2798 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2799 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2802 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2803 return non-zero if it is safe to reverse this comparison. It is if our
2804 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2805 this is known to be an integer comparison. */
2808 can_reverse_comparison_p (comparison, insn)
2814 /* If this is not actually a comparison, we can't reverse it. */
2815 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2818 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2819 /* If this is an NE comparison, it is safe to reverse it to an EQ
2820 comparison and vice versa, even for floating point. If no operands
2821 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2822 always false and NE is always true, so the reversal is also valid. */
2824 || GET_CODE (comparison) == NE
2825 || GET_CODE (comparison) == EQ)
2828 arg0 = XEXP (comparison, 0);
2830 /* Make sure ARG0 is one of the actual objects being compared. If we
2831 can't do this, we can't be sure the comparison can be reversed.
2833 Handle cc0 and a MODE_CC register. */
2834 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2840 rtx prev = prev_nonnote_insn (insn);
2841 rtx set = single_set (prev);
2843 if (set == 0 || SET_DEST (set) != arg0)
2846 arg0 = SET_SRC (set);
2848 if (GET_CODE (arg0) == COMPARE)
2849 arg0 = XEXP (arg0, 0);
2852 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2853 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2854 return (GET_CODE (arg0) == CONST_INT
2855 || (GET_MODE (arg0) != VOIDmode
2856 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2857 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2860 /* Given an rtx-code for a comparison, return the code
2861 for the negated comparison.
2862 WATCH OUT! reverse_condition is not safe to use on a jump
2863 that might be acting on the results of an IEEE floating point comparison,
2864 because of the special treatment of non-signaling nans in comparisons.
2865 Use can_reverse_comparison_p to be sure. */
2868 reverse_condition (code)
2909 /* Similar, but return the code when two operands of a comparison are swapped.
2910 This IS safe for IEEE floating-point. */
2913 swap_condition (code)
2952 /* Given a comparison CODE, return the corresponding unsigned comparison.
2953 If CODE is an equality comparison or already an unsigned comparison,
2954 CODE is returned. */
2957 unsigned_condition (code)
2987 /* Similarly, return the signed version of a comparison. */
2990 signed_condition (code)
3020 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3021 truth of CODE1 implies the truth of CODE2. */
3024 comparison_dominates_p (code1, code2)
3025 enum rtx_code code1, code2;
3033 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3038 if (code2 == LE || code2 == NE)
3043 if (code2 == GE || code2 == NE)
3048 if (code2 == LEU || code2 == NE)
3053 if (code2 == GEU || code2 == NE)
3061 /* Return 1 if INSN is an unconditional jump and nothing else. */
3067 return (GET_CODE (insn) == JUMP_INSN
3068 && GET_CODE (PATTERN (insn)) == SET
3069 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3070 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3073 /* Return nonzero if INSN is a (possibly) conditional jump
3074 and nothing more. */
3080 register rtx x = PATTERN (insn);
3081 if (GET_CODE (x) != SET)
3083 if (GET_CODE (SET_DEST (x)) != PC)
3085 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3087 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3089 if (XEXP (SET_SRC (x), 2) == pc_rtx
3090 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3091 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3093 if (XEXP (SET_SRC (x), 1) == pc_rtx
3094 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3095 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3100 /* Return nonzero if INSN is a (possibly) conditional jump
3101 and nothing more. */
3104 condjump_in_parallel_p (insn)
3107 register rtx x = PATTERN (insn);
3109 if (GET_CODE (x) != PARALLEL)
3112 x = XVECEXP (x, 0, 0);
3114 if (GET_CODE (x) != SET)
3116 if (GET_CODE (SET_DEST (x)) != PC)
3118 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3120 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3122 if (XEXP (SET_SRC (x), 2) == pc_rtx
3123 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3124 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3126 if (XEXP (SET_SRC (x), 1) == pc_rtx
3127 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3128 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3133 /* Return 1 if X is an RTX that does nothing but set the condition codes
3134 and CLOBBER or USE registers.
3135 Return -1 if X does explicitly set the condition codes,
3136 but also does other things. */
3143 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3145 if (GET_CODE (x) == PARALLEL)
3149 int other_things = 0;
3150 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3152 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3153 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3155 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3158 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3166 /* Follow any unconditional jump at LABEL;
3167 return the ultimate label reached by any such chain of jumps.
3168 If LABEL is not followed by a jump, return LABEL.
3169 If the chain loops or we can't find end, return LABEL,
3170 since that tells caller to avoid changing the insn.
3172 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3173 a USE or CLOBBER. */
3176 follow_jumps (label)
3181 register rtx value = label;
3186 && (insn = next_active_insn (value)) != 0
3187 && GET_CODE (insn) == JUMP_INSN
3188 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3189 || GET_CODE (PATTERN (insn)) == RETURN)
3190 && (next = NEXT_INSN (insn))
3191 && GET_CODE (next) == BARRIER);
3194 /* Don't chain through the insn that jumps into a loop
3195 from outside the loop,
3196 since that would create multiple loop entry jumps
3197 and prevent loop optimization. */
3199 if (!reload_completed)
3200 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3201 if (GET_CODE (tem) == NOTE
3202 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
3205 /* If we have found a cycle, make the insn jump to itself. */
3206 if (JUMP_LABEL (insn) == label)
3209 tem = next_active_insn (JUMP_LABEL (insn));
3210 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3211 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3214 value = JUMP_LABEL (insn);
3221 /* Assuming that field IDX of X is a vector of label_refs,
3222 replace each of them by the ultimate label reached by it.
3223 Return nonzero if a change is made.
3224 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3227 tension_vector_labels (x, idx)
3233 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3235 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3236 register rtx nlabel = follow_jumps (olabel);
3237 if (nlabel && nlabel != olabel)
3239 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3240 ++LABEL_NUSES (nlabel);
3241 if (--LABEL_NUSES (olabel) == 0)
3242 delete_insn (olabel);
3249 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3250 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3251 in INSN, then store one of them in JUMP_LABEL (INSN).
3252 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3253 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3254 Also, when there are consecutive labels, canonicalize on the last of them.
3256 Note that two labels separated by a loop-beginning note
3257 must be kept distinct if we have not yet done loop-optimization,
3258 because the gap between them is where loop-optimize
3259 will want to move invariant code to. CROSS_JUMP tells us
3260 that loop-optimization is done with.
3262 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3263 two labels distinct if they are separated by only USE or CLOBBER insns. */
3266 mark_jump_label (x, insn, cross_jump)
3271 register RTX_CODE code = GET_CODE (x);
3289 /* If this is a constant-pool reference, see if it is a label. */
3290 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3291 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3292 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3297 rtx label = XEXP (x, 0);
3302 if (GET_CODE (label) != CODE_LABEL)
3305 /* Ignore references to labels of containing functions. */
3306 if (LABEL_REF_NONLOCAL_P (x))
3309 /* If there are other labels following this one,
3310 replace it with the last of the consecutive labels. */
3311 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3313 if (GET_CODE (next) == CODE_LABEL)
3315 else if (cross_jump && GET_CODE (next) == INSN
3316 && (GET_CODE (PATTERN (next)) == USE
3317 || GET_CODE (PATTERN (next)) == CLOBBER))
3319 else if (GET_CODE (next) != NOTE)
3321 else if (! cross_jump
3322 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3323 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
3327 XEXP (x, 0) = label;
3328 ++LABEL_NUSES (label);
3332 if (GET_CODE (insn) == JUMP_INSN)
3333 JUMP_LABEL (insn) = label;
3335 /* If we've changed OLABEL and we had a REG_LABEL note
3336 for it, update it as well. */
3337 else if (label != olabel
3338 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3339 XEXP (note, 0) = label;
3341 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3343 else if (! find_reg_note (insn, REG_LABEL, label))
3345 rtx next = next_real_insn (label);
3346 /* Don't record labels that refer to dispatch tables.
3347 This is not necessary, since the tablejump
3348 references the same label.
3349 And if we did record them, flow.c would make worse code. */
3351 || ! (GET_CODE (next) == JUMP_INSN
3352 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3353 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
3354 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
3361 /* Do walk the labels in a vector, but not the first operand of an
3362 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3366 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3368 for (i = 0; i < XVECLEN (x, eltnum); i++)
3369 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3374 fmt = GET_RTX_FORMAT (code);
3375 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3378 mark_jump_label (XEXP (x, i), insn, cross_jump);
3379 else if (fmt[i] == 'E')
3382 for (j = 0; j < XVECLEN (x, i); j++)
3383 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3388 /* If all INSN does is set the pc, delete it,
3389 and delete the insn that set the condition codes for it
3390 if that's what the previous thing was. */
3396 register rtx set = single_set (insn);
3398 if (set && GET_CODE (SET_DEST (set)) == PC)
3399 delete_computation (insn);
3402 /* Delete INSN and recursively delete insns that compute values used only
3403 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3404 If we are running before flow.c, we need do nothing since flow.c will
3405 delete dead code. We also can't know if the registers being used are
3406 dead or not at this point.
3408 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3409 nothing other than set a register that dies in this insn, we can delete
3412 On machines with CC0, if CC0 is used in this insn, we may be able to
3413 delete the insn that set it. */
3416 delete_computation (insn)
3422 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3424 rtx prev = prev_nonnote_insn (insn);
3425 /* We assume that at this stage
3426 CC's are always set explicitly
3427 and always immediately before the jump that
3428 will use them. So if the previous insn
3429 exists to set the CC's, delete it
3430 (unless it performs auto-increments, etc.). */
3431 if (prev && GET_CODE (prev) == INSN
3432 && sets_cc0_p (PATTERN (prev)))
3434 if (sets_cc0_p (PATTERN (prev)) > 0
3435 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3436 delete_computation (prev);
3438 /* Otherwise, show that cc0 won't be used. */
3439 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
3440 cc0_rtx, REG_NOTES (prev));
3445 for (note = REG_NOTES (insn); note; note = next)
3449 next = XEXP (note, 1);
3451 if (REG_NOTE_KIND (note) != REG_DEAD
3452 /* Verify that the REG_NOTE is legitimate. */
3453 || GET_CODE (XEXP (note, 0)) != REG)
3456 for (our_prev = prev_nonnote_insn (insn);
3457 our_prev && GET_CODE (our_prev) == INSN;
3458 our_prev = prev_nonnote_insn (our_prev))
3460 /* If we reach a SEQUENCE, it is too complex to try to
3461 do anything with it, so give up. */
3462 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3465 if (GET_CODE (PATTERN (our_prev)) == USE
3466 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3467 /* reorg creates USEs that look like this. We leave them
3468 alone because reorg needs them for its own purposes. */
3471 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3473 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3476 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3478 /* If we find a SET of something else, we can't
3483 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3485 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3487 if (GET_CODE (part) == SET
3488 && SET_DEST (part) != XEXP (note, 0))
3492 if (i == XVECLEN (PATTERN (our_prev), 0))
3493 delete_computation (our_prev);
3495 else if (GET_CODE (PATTERN (our_prev)) == SET
3496 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3497 delete_computation (our_prev);
3502 /* If OUR_PREV references the register that dies here, it is an
3503 additional use. Hence any prior SET isn't dead. However, this
3504 insn becomes the new place for the REG_DEAD note. */
3505 if (reg_overlap_mentioned_p (XEXP (note, 0),
3506 PATTERN (our_prev)))
3508 XEXP (note, 1) = REG_NOTES (our_prev);
3509 REG_NOTES (our_prev) = note;
3518 /* Delete insn INSN from the chain of insns and update label ref counts.
3519 May delete some following insns as a consequence; may even delete
3520 a label elsewhere and insns that follow it.
3522 Returns the first insn after INSN that was not deleted. */
3528 register rtx next = NEXT_INSN (insn);
3529 register rtx prev = PREV_INSN (insn);
3530 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3531 register int dont_really_delete = 0;
3533 while (next && INSN_DELETED_P (next))
3534 next = NEXT_INSN (next);
3536 /* This insn is already deleted => return first following nondeleted. */
3537 if (INSN_DELETED_P (insn))
3540 /* Don't delete user-declared labels. Convert them to special NOTEs
3542 if (was_code_label && LABEL_NAME (insn) != 0
3543 && optimize && ! dont_really_delete)
3545 PUT_CODE (insn, NOTE);
3546 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3547 NOTE_SOURCE_FILE (insn) = 0;
3548 dont_really_delete = 1;
3551 /* Mark this insn as deleted. */
3552 INSN_DELETED_P (insn) = 1;
3554 /* If this is an unconditional jump, delete it from the jump chain. */
3555 if (simplejump_p (insn))
3556 delete_from_jump_chain (insn);
3558 /* If instruction is followed by a barrier,
3559 delete the barrier too. */
3561 if (next != 0 && GET_CODE (next) == BARRIER)
3563 INSN_DELETED_P (next) = 1;
3564 next = NEXT_INSN (next);
3567 /* Patch out INSN (and the barrier if any) */
3569 if (optimize && ! dont_really_delete)
3573 NEXT_INSN (prev) = next;
3574 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3575 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3576 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3581 PREV_INSN (next) = prev;
3582 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3583 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3586 if (prev && NEXT_INSN (prev) == 0)
3587 set_last_insn (prev);
3590 /* If deleting a jump, decrement the count of the label,
3591 and delete the label if it is now unused. */
3593 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3594 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3596 /* This can delete NEXT or PREV,
3597 either directly if NEXT is JUMP_LABEL (INSN),
3598 or indirectly through more levels of jumps. */
3599 delete_insn (JUMP_LABEL (insn));
3600 /* I feel a little doubtful about this loop,
3601 but I see no clean and sure alternative way
3602 to find the first insn after INSN that is not now deleted.
3603 I hope this works. */
3604 while (next && INSN_DELETED_P (next))
3605 next = NEXT_INSN (next);
3609 /* Likewise if we're deleting a dispatch table. */
3611 if (GET_CODE (insn) == JUMP_INSN
3612 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3613 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3615 rtx pat = PATTERN (insn);
3616 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3617 int len = XVECLEN (pat, diff_vec_p);
3619 for (i = 0; i < len; i++)
3620 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3621 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3622 while (next && INSN_DELETED_P (next))
3623 next = NEXT_INSN (next);
3627 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3628 prev = PREV_INSN (prev);
3630 /* If INSN was a label and a dispatch table follows it,
3631 delete the dispatch table. The tablejump must have gone already.
3632 It isn't useful to fall through into a table. */
3635 && NEXT_INSN (insn) != 0
3636 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3637 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3638 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3639 next = delete_insn (NEXT_INSN (insn));
3641 /* If INSN was a label, delete insns following it if now unreachable. */
3643 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3645 register RTX_CODE code;
3647 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3648 || code == NOTE || code == BARRIER
3649 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3652 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3653 next = NEXT_INSN (next);
3654 /* Keep going past other deleted labels to delete what follows. */
3655 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3656 next = NEXT_INSN (next);
3658 /* Note: if this deletes a jump, it can cause more
3659 deletion of unreachable code, after a different label.
3660 As long as the value from this recursive call is correct,
3661 this invocation functions correctly. */
3662 next = delete_insn (next);
3669 /* Advance from INSN till reaching something not deleted
3670 then return that. May return INSN itself. */
3673 next_nondeleted_insn (insn)
3676 while (INSN_DELETED_P (insn))
3677 insn = NEXT_INSN (insn);
3681 /* Delete a range of insns from FROM to TO, inclusive.
3682 This is for the sake of peephole optimization, so assume
3683 that whatever these insns do will still be done by a new
3684 peephole insn that will replace them. */
3687 delete_for_peephole (from, to)
3688 register rtx from, to;
3690 register rtx insn = from;
3694 register rtx next = NEXT_INSN (insn);
3695 register rtx prev = PREV_INSN (insn);
3697 if (GET_CODE (insn) != NOTE)
3699 INSN_DELETED_P (insn) = 1;
3701 /* Patch this insn out of the chain. */
3702 /* We don't do this all at once, because we
3703 must preserve all NOTEs. */
3705 NEXT_INSN (prev) = next;
3708 PREV_INSN (next) = prev;
3716 /* Note that if TO is an unconditional jump
3717 we *do not* delete the BARRIER that follows,
3718 since the peephole that replaces this sequence
3719 is also an unconditional jump in that case. */
3722 /* Invert the condition of the jump JUMP, and make it jump
3723 to label NLABEL instead of where it jumps now. */
3726 invert_jump (jump, nlabel)
3729 /* We have to either invert the condition and change the label or
3730 do neither. Either operation could fail. We first try to invert
3731 the jump. If that succeeds, we try changing the label. If that fails,
3732 we invert the jump back to what it was. */
3734 if (! invert_exp (PATTERN (jump), jump))
3737 if (redirect_jump (jump, nlabel))
3740 if (! invert_exp (PATTERN (jump), jump))
3741 /* This should just be putting it back the way it was. */
3747 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3749 Return 1 if we can do so, 0 if we cannot find a way to do so that
3750 matches a pattern. */
3753 invert_exp (x, insn)
3757 register RTX_CODE code;
3761 code = GET_CODE (x);
3763 if (code == IF_THEN_ELSE)
3765 register rtx comp = XEXP (x, 0);
3768 /* We can do this in two ways: The preferable way, which can only
3769 be done if this is not an integer comparison, is to reverse
3770 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3771 of the IF_THEN_ELSE. If we can't do either, fail. */
3773 if (can_reverse_comparison_p (comp, insn)
3774 && validate_change (insn, &XEXP (x, 0),
3775 gen_rtx (reverse_condition (GET_CODE (comp)),
3776 GET_MODE (comp), XEXP (comp, 0),
3777 XEXP (comp, 1)), 0))
3781 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3782 validate_change (insn, &XEXP (x, 2), tem, 1);
3783 return apply_change_group ();
3786 fmt = GET_RTX_FORMAT (code);
3787 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3790 if (! invert_exp (XEXP (x, i), insn))
3795 for (j = 0; j < XVECLEN (x, i); j++)
3796 if (!invert_exp (XVECEXP (x, i, j), insn))
3804 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3805 If the old jump target label is unused as a result,
3806 it and the code following it may be deleted.
3808 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3811 The return value will be 1 if the change was made, 0 if it wasn't (this
3812 can only occur for NLABEL == 0). */
3815 redirect_jump (jump, nlabel)
3818 register rtx olabel = JUMP_LABEL (jump);
3820 if (nlabel == olabel)
3823 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3826 /* If this is an unconditional branch, delete it from the jump_chain of
3827 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3828 have UID's in range and JUMP_CHAIN is valid). */
3829 if (jump_chain && (simplejump_p (jump)
3830 || GET_CODE (PATTERN (jump)) == RETURN))
3832 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3834 delete_from_jump_chain (jump);
3835 if (label_index < max_jump_chain
3836 && INSN_UID (jump) < max_jump_chain)
3838 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3839 jump_chain[label_index] = jump;
3843 JUMP_LABEL (jump) = nlabel;
3845 ++LABEL_NUSES (nlabel);
3847 if (olabel && --LABEL_NUSES (olabel) == 0)
3848 delete_insn (olabel);
3853 /* Delete the instruction JUMP from any jump chain it might be on. */
3856 delete_from_jump_chain (jump)
3860 rtx olabel = JUMP_LABEL (jump);
3862 /* Handle unconditional jumps. */
3863 if (jump_chain && olabel != 0
3864 && INSN_UID (olabel) < max_jump_chain
3865 && simplejump_p (jump))
3866 index = INSN_UID (olabel);
3867 /* Handle return insns. */
3868 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3872 if (jump_chain[index] == jump)
3873 jump_chain[index] = jump_chain[INSN_UID (jump)];
3878 for (insn = jump_chain[index];
3880 insn = jump_chain[INSN_UID (insn)])
3881 if (jump_chain[INSN_UID (insn)] == jump)
3883 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3889 /* If NLABEL is nonzero, throughout the rtx at LOC,
3890 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3891 zero, alter (RETURN) to (LABEL_REF NLABEL).
3893 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3894 validity with validate_change. Convert (set (pc) (label_ref olabel))
3897 Return 0 if we found a change we would like to make but it is invalid.
3898 Otherwise, return 1. */
3901 redirect_exp (loc, olabel, nlabel, insn)
3906 register rtx x = *loc;
3907 register RTX_CODE code = GET_CODE (x);
3911 if (code == LABEL_REF)
3913 if (XEXP (x, 0) == olabel)
3916 XEXP (x, 0) = nlabel;
3918 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3922 else if (code == RETURN && olabel == 0)
3924 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3925 if (loc == &PATTERN (insn))
3926 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3927 return validate_change (insn, loc, x, 0);
3930 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3931 && GET_CODE (SET_SRC (x)) == LABEL_REF
3932 && XEXP (SET_SRC (x), 0) == olabel)
3933 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3935 fmt = GET_RTX_FORMAT (code);
3936 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3939 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3944 for (j = 0; j < XVECLEN (x, i); j++)
3945 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3953 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3955 If the old jump target label (before the dispatch table) becomes unused,
3956 it and the dispatch table may be deleted. In that case, find the insn
3957 before the jump references that label and delete it and logical successors
3961 redirect_tablejump (jump, nlabel)
3964 register rtx olabel = JUMP_LABEL (jump);
3966 /* Add this jump to the jump_chain of NLABEL. */
3967 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3968 && INSN_UID (jump) < max_jump_chain)
3970 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3971 jump_chain[INSN_UID (nlabel)] = jump;
3974 PATTERN (jump) = gen_jump (nlabel);
3975 JUMP_LABEL (jump) = nlabel;
3976 ++LABEL_NUSES (nlabel);
3977 INSN_CODE (jump) = -1;
3979 if (--LABEL_NUSES (olabel) == 0)
3981 delete_labelref_insn (jump, olabel, 0);
3982 delete_insn (olabel);
3986 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3987 If we found one, delete it and then delete this insn if DELETE_THIS is
3988 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3991 delete_labelref_insn (insn, label, delete_this)
3998 if (GET_CODE (insn) != NOTE
3999 && reg_mentioned_p (label, PATTERN (insn)))
4010 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4011 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4025 /* Like rtx_equal_p except that it considers two REGs as equal
4026 if they renumber to the same value and considers two commutative
4027 operations to be the same if the order of the operands has been
4031 rtx_renumbered_equal_p (x, y)
4035 register RTX_CODE code = GET_CODE (x);
4041 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4042 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4043 && GET_CODE (SUBREG_REG (y)) == REG)))
4045 int reg_x = -1, reg_y = -1;
4046 int word_x = 0, word_y = 0;
4048 if (GET_MODE (x) != GET_MODE (y))
4051 /* If we haven't done any renumbering, don't
4052 make any assumptions. */
4053 if (reg_renumber == 0)
4054 return rtx_equal_p (x, y);
4058 reg_x = REGNO (SUBREG_REG (x));
4059 word_x = SUBREG_WORD (x);
4061 if (reg_renumber[reg_x] >= 0)
4063 reg_x = reg_renumber[reg_x] + word_x;
4071 if (reg_renumber[reg_x] >= 0)
4072 reg_x = reg_renumber[reg_x];
4075 if (GET_CODE (y) == SUBREG)
4077 reg_y = REGNO (SUBREG_REG (y));
4078 word_y = SUBREG_WORD (y);
4080 if (reg_renumber[reg_y] >= 0)
4082 reg_y = reg_renumber[reg_y];
4090 if (reg_renumber[reg_y] >= 0)
4091 reg_y = reg_renumber[reg_y];
4094 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4097 /* Now we have disposed of all the cases
4098 in which different rtx codes can match. */
4099 if (code != GET_CODE (y))
4111 return INTVAL (x) == INTVAL (y);
4114 /* We can't assume nonlocal labels have their following insns yet. */
4115 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4116 return XEXP (x, 0) == XEXP (y, 0);
4118 /* Two label-refs are equivalent if they point at labels
4119 in the same position in the instruction stream. */
4120 return (next_real_insn (XEXP (x, 0))
4121 == next_real_insn (XEXP (y, 0)));
4124 return XSTR (x, 0) == XSTR (y, 0);
4127 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4129 if (GET_MODE (x) != GET_MODE (y))
4132 /* For commutative operations, the RTX match if the operand match in any
4133 order. Also handle the simple binary and unary cases without a loop. */
4134 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4135 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4136 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4137 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4138 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4139 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4140 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4141 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4142 else if (GET_RTX_CLASS (code) == '1')
4143 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4145 /* Compare the elements. If any pair of corresponding elements
4146 fail to match, return 0 for the whole things. */
4148 fmt = GET_RTX_FORMAT (code);
4149 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4155 if (XWINT (x, i) != XWINT (y, i))
4160 if (XINT (x, i) != XINT (y, i))
4165 if (strcmp (XSTR (x, i), XSTR (y, i)))
4170 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4175 if (XEXP (x, i) != XEXP (y, i))
4182 if (XVECLEN (x, i) != XVECLEN (y, i))
4184 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4185 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4196 /* If X is a hard register or equivalent to one or a subregister of one,
4197 return the hard register number. If X is a pseudo register that was not
4198 assigned a hard register, return the pseudo register number. Otherwise,
4199 return -1. Any rtx is valid for X. */
4205 if (GET_CODE (x) == REG)
4207 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4208 return reg_renumber[REGNO (x)];
4211 if (GET_CODE (x) == SUBREG)
4213 int base = true_regnum (SUBREG_REG (x));
4214 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4215 return SUBREG_WORD (x) + base;
4220 /* Optimize code of the form:
4222 for (x = a[i]; x; ...)
4224 for (x = a[i]; x; ...)
4228 Loop optimize will change the above code into
4232 { ...; if (! (x = ...)) break; }
4235 { ...; if (! (x = ...)) break; }
4238 In general, if the first test fails, the program can branch
4239 directly to `foo' and skip the second try which is doomed to fail.
4240 We run this after loop optimization and before flow analysis. */
4242 /* When comparing the insn patterns, we track the fact that different
4243 pseudo-register numbers may have been used in each computation.
4244 The following array stores an equivalence -- same_regs[I] == J means
4245 that pseudo register I was used in the first set of tests in a context
4246 where J was used in the second set. We also count the number of such
4247 pending equivalences. If nonzero, the expressions really aren't the
4250 static int *same_regs;
4252 static int num_same_regs;
4254 /* Track any registers modified between the target of the first jump and
4255 the second jump. They never compare equal. */
4257 static char *modified_regs;
4259 /* Record if memory was modified. */
4261 static int modified_mem;
4263 /* Called via note_stores on each insn between the target of the first
4264 branch and the second branch. It marks any changed registers. */
4267 mark_modified_reg (dest, x)
4273 if (GET_CODE (dest) == SUBREG)
4274 dest = SUBREG_REG (dest);
4276 if (GET_CODE (dest) == MEM)
4279 if (GET_CODE (dest) != REG)
4282 regno = REGNO (dest);
4283 if (regno >= FIRST_PSEUDO_REGISTER)
4284 modified_regs[regno] = 1;
4286 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4287 modified_regs[regno + i] = 1;
4290 /* F is the first insn in the chain of insns. */
4293 thread_jumps (f, max_reg, flag_before_loop)
4296 int flag_before_loop;
4298 /* Basic algorithm is to find a conditional branch,
4299 the label it may branch to, and the branch after
4300 that label. If the two branches test the same condition,
4301 walk back from both branch paths until the insn patterns
4302 differ, or code labels are hit. If we make it back to
4303 the target of the first branch, then we know that the first branch
4304 will either always succeed or always fail depending on the relative
4305 senses of the two branches. So adjust the first branch accordingly
4308 rtx label, b1, b2, t1, t2;
4309 enum rtx_code code1, code2;
4310 rtx b1op0, b1op1, b2op0, b2op1;
4315 /* Allocate register tables and quick-reset table. */
4316 modified_regs = (char *) alloca (max_reg * sizeof (char));
4317 same_regs = (int *) alloca (max_reg * sizeof (int));
4318 all_reset = (int *) alloca (max_reg * sizeof (int));
4319 for (i = 0; i < max_reg; i++)
4326 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4328 /* Get to a candidate branch insn. */
4329 if (GET_CODE (b1) != JUMP_INSN
4330 || ! condjump_p (b1) || simplejump_p (b1)
4331 || JUMP_LABEL (b1) == 0)
4334 bzero (modified_regs, max_reg * sizeof (char));
4337 bcopy ((char *) all_reset, (char *) same_regs,
4338 max_reg * sizeof (int));
4341 label = JUMP_LABEL (b1);
4343 /* Look for a branch after the target. Record any registers and
4344 memory modified between the target and the branch. Stop when we
4345 get to a label since we can't know what was changed there. */
4346 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4348 if (GET_CODE (b2) == CODE_LABEL)
4351 else if (GET_CODE (b2) == JUMP_INSN)
4353 /* If this is an unconditional jump and is the only use of
4354 its target label, we can follow it. */
4355 if (simplejump_p (b2)
4356 && JUMP_LABEL (b2) != 0
4357 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4359 b2 = JUMP_LABEL (b2);
4366 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4369 if (GET_CODE (b2) == CALL_INSN)
4372 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4373 if (call_used_regs[i] && ! fixed_regs[i]
4374 && i != STACK_POINTER_REGNUM
4375 && i != FRAME_POINTER_REGNUM
4376 && i != HARD_FRAME_POINTER_REGNUM
4377 && i != ARG_POINTER_REGNUM)
4378 modified_regs[i] = 1;
4381 note_stores (PATTERN (b2), mark_modified_reg);
4384 /* Check the next candidate branch insn from the label
4387 || GET_CODE (b2) != JUMP_INSN
4389 || ! condjump_p (b2)
4390 || simplejump_p (b2))
4393 /* Get the comparison codes and operands, reversing the
4394 codes if appropriate. If we don't have comparison codes,
4395 we can't do anything. */
4396 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4397 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4398 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4399 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4400 code1 = reverse_condition (code1);
4402 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4403 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4404 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4405 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4406 code2 = reverse_condition (code2);
4408 /* If they test the same things and knowing that B1 branches
4409 tells us whether or not B2 branches, check if we
4410 can thread the branch. */
4411 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4412 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4413 && (comparison_dominates_p (code1, code2)
4414 || comparison_dominates_p (code1, reverse_condition (code2))))
4416 t1 = prev_nonnote_insn (b1);
4417 t2 = prev_nonnote_insn (b2);
4419 while (t1 != 0 && t2 != 0)
4423 /* We have reached the target of the first branch.
4424 If there are no pending register equivalents,
4425 we know that this branch will either always
4426 succeed (if the senses of the two branches are
4427 the same) or always fail (if not). */
4430 if (num_same_regs != 0)
4433 if (comparison_dominates_p (code1, code2))
4434 new_label = JUMP_LABEL (b2);
4436 new_label = get_label_after (b2);
4438 if (JUMP_LABEL (b1) != new_label)
4440 rtx prev = PREV_INSN (new_label);
4442 if (flag_before_loop
4443 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4445 /* Don't thread to the loop label. If a loop
4446 label is reused, loop optimization will
4447 be disabled for that loop. */
4448 new_label = gen_label_rtx ();
4449 emit_label_after (new_label, PREV_INSN (prev));
4451 changed |= redirect_jump (b1, new_label);
4456 /* If either of these is not a normal insn (it might be
4457 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4458 have already been skipped above.) Similarly, fail
4459 if the insns are different. */
4460 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4461 || recog_memoized (t1) != recog_memoized (t2)
4462 || ! rtx_equal_for_thread_p (PATTERN (t1),
4466 t1 = prev_nonnote_insn (t1);
4467 t2 = prev_nonnote_insn (t2);
4474 /* This is like RTX_EQUAL_P except that it knows about our handling of
4475 possibly equivalent registers and knows to consider volatile and
4476 modified objects as not equal.
4478 YINSN is the insn containing Y. */
4481 rtx_equal_for_thread_p (x, y, yinsn)
4487 register enum rtx_code code;
4490 code = GET_CODE (x);
4491 /* Rtx's of different codes cannot be equal. */
4492 if (code != GET_CODE (y))
4495 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4496 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4498 if (GET_MODE (x) != GET_MODE (y))
4501 /* For commutative operations, the RTX match if the operand match in any
4502 order. Also handle the simple binary and unary cases without a loop. */
4503 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4504 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4505 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4506 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4507 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4508 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4509 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4510 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4511 else if (GET_RTX_CLASS (code) == '1')
4512 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4514 /* Handle special-cases first. */
4518 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4521 /* If neither is user variable or hard register, check for possible
4523 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4524 || REGNO (x) < FIRST_PSEUDO_REGISTER
4525 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4528 if (same_regs[REGNO (x)] == -1)
4530 same_regs[REGNO (x)] = REGNO (y);
4533 /* If this is the first time we are seeing a register on the `Y'
4534 side, see if it is the last use. If not, we can't thread the
4535 jump, so mark it as not equivalent. */
4536 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
4542 return (same_regs[REGNO (x)] == REGNO (y));
4547 /* If memory modified or either volatile, not equivalent.
4548 Else, check address. */
4549 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4552 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4555 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4561 /* Cancel a pending `same_regs' if setting equivalenced registers.
4562 Then process source. */
4563 if (GET_CODE (SET_DEST (x)) == REG
4564 && GET_CODE (SET_DEST (y)) == REG)
4566 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4568 same_regs[REGNO (SET_DEST (x))] = -1;
4571 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4575 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4578 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4581 return XEXP (x, 0) == XEXP (y, 0);
4584 return XSTR (x, 0) == XSTR (y, 0);
4590 fmt = GET_RTX_FORMAT (code);
4591 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4596 if (XWINT (x, i) != XWINT (y, i))
4602 if (XINT (x, i) != XINT (y, i))
4608 /* Two vectors must have the same length. */
4609 if (XVECLEN (x, i) != XVECLEN (y, i))
4612 /* And the corresponding elements must match. */
4613 for (j = 0; j < XVECLEN (x, i); j++)
4614 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4615 XVECEXP (y, i, j), yinsn) == 0)
4620 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4626 if (strcmp (XSTR (x, i), XSTR (y, i)))
4631 /* These are just backpointers, so they don't matter. */
4637 /* It is believed that rtx's at this level will never
4638 contain anything but integers and other rtx's,
4639 except for within LABEL_REFs and SYMBOL_REFs. */