1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-95, 1996 Free Software Foundation, Inc.b
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
57 #include "hard-reg-set.h"
59 #include "insn-config.h"
60 #include "insn-flags.h"
65 /* ??? Eventually must record somehow the labels used by jumps
66 from nested functions. */
67 /* Pre-record the next or previous real insn for each label?
68 No, this pass is very fast anyway. */
69 /* Condense consecutive labels?
70 This would make life analysis faster, maybe. */
71 /* Optimize jump y; x: ... y: jumpif... x?
72 Don't know if it is worth bothering with. */
73 /* Optimize two cases of conditional jump to conditional jump?
74 This can never delete any instruction or make anything dead,
75 or even change what is live at any point.
76 So perhaps let combiner do it. */
78 /* Vector indexed by uid.
79 For each CODE_LABEL, index by its uid to get first unconditional jump
80 that jumps to the label.
81 For each JUMP_INSN, index by its uid to get the next unconditional jump
82 that jumps to the same label.
83 Element 0 is the start of a chain of all return insns.
84 (It is safe to use element 0 because insn uid 0 is not used. */
86 static rtx *jump_chain;
88 /* List of labels referred to from initializers.
89 These can never be deleted. */
92 /* Maximum index in jump_chain. */
94 static int max_jump_chain;
96 /* Set nonzero by jump_optimize if control can fall through
97 to the end of the function. */
100 /* Indicates whether death notes are significant in cross jump analysis.
101 Normally they are not significant, because of A and B jump to C,
102 and R dies in A, it must die in B. But this might not be true after
103 stack register conversion, and we must compare death notes in that
106 static int cross_jump_death_matters = 0;
108 static int duplicate_loop_exit_test PROTO((rtx));
109 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
110 static void do_cross_jump PROTO((rtx, rtx, rtx));
111 static int jump_back_p PROTO((rtx, rtx));
112 static int tension_vector_labels PROTO((rtx, int));
113 static void mark_jump_label PROTO((rtx, rtx, int));
114 static void delete_computation PROTO((rtx));
115 static void delete_from_jump_chain PROTO((rtx));
116 static int delete_labelref_insn PROTO((rtx, rtx, int));
117 static void redirect_tablejump PROTO((rtx, rtx));
119 /* Delete no-op jumps and optimize jumps to jumps
120 and jumps around jumps.
121 Delete unused labels and unreachable code.
123 If CROSS_JUMP is 1, detect matching code
124 before a jump and its destination and unify them.
125 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
127 If NOOP_MOVES is nonzero, delete no-op move insns.
129 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
130 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
132 If `optimize' is zero, don't change any code,
133 just determine whether control drops off the end of the function.
134 This case occurs when we have -W and not -O.
135 It works because `delete_insn' checks the value of `optimize'
136 and refrains from actually deleting when that is 0. */
139 jump_optimize (f, cross_jump, noop_moves, after_regscan)
145 register rtx insn, next, note;
151 cross_jump_death_matters = (cross_jump == 2);
153 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
154 notes whose labels don't occur in the insn any more. */
156 for (insn = f; insn; insn = NEXT_INSN (insn))
158 if (GET_CODE (insn) == CODE_LABEL)
159 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
160 else if (GET_CODE (insn) == JUMP_INSN)
161 JUMP_LABEL (insn) = 0;
162 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
163 for (note = REG_NOTES (insn); note; note = next)
165 next = XEXP (note, 1);
166 if (REG_NOTE_KIND (note) == REG_LABEL
167 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
168 remove_note (insn, note);
171 if (INSN_UID (insn) > max_uid)
172 max_uid = INSN_UID (insn);
177 /* Delete insns following barriers, up to next label. */
179 for (insn = f; insn;)
181 if (GET_CODE (insn) == BARRIER)
183 insn = NEXT_INSN (insn);
184 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
186 if (GET_CODE (insn) == NOTE
187 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
188 insn = NEXT_INSN (insn);
190 insn = delete_insn (insn);
192 /* INSN is now the code_label. */
195 insn = NEXT_INSN (insn);
198 /* Leave some extra room for labels and duplicate exit test insns
200 max_jump_chain = max_uid * 14 / 10;
201 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
202 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
204 /* Mark the label each jump jumps to.
205 Combine consecutive labels, and count uses of labels.
207 For each label, make a chain (using `jump_chain')
208 of all the *unconditional* jumps that jump to it;
209 also make a chain of all returns. */
211 for (insn = f; insn; insn = NEXT_INSN (insn))
212 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
213 && ! INSN_DELETED_P (insn))
215 mark_jump_label (PATTERN (insn), insn, cross_jump);
216 if (GET_CODE (insn) == JUMP_INSN)
218 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
220 jump_chain[INSN_UID (insn)]
221 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
222 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
224 if (GET_CODE (PATTERN (insn)) == RETURN)
226 jump_chain[INSN_UID (insn)] = jump_chain[0];
227 jump_chain[0] = insn;
232 /* Keep track of labels used from static data;
233 they cannot ever be deleted. */
235 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
236 LABEL_NUSES (XEXP (insn, 0))++;
238 check_exception_handler_labels ();
240 /* Keep track of labels used for marking handlers for exception
241 regions; they cannot usually be deleted. */
243 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
244 LABEL_NUSES (XEXP (insn, 0))++;
246 exception_optimize ();
248 /* Delete all labels already not referenced.
249 Also find the last insn. */
252 for (insn = f; insn; )
254 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
255 insn = delete_insn (insn);
259 insn = NEXT_INSN (insn);
265 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
266 If so record that this function can drop off the end. */
272 /* One label can follow the end-note: the return label. */
273 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
274 /* Ordinary insns can follow it if returning a structure. */
275 || GET_CODE (insn) == INSN
276 /* If machine uses explicit RETURN insns, no epilogue,
277 then one of them follows the note. */
278 || (GET_CODE (insn) == JUMP_INSN
279 && GET_CODE (PATTERN (insn)) == RETURN)
280 /* A barrier can follow the return insn. */
281 || GET_CODE (insn) == BARRIER
282 /* Other kinds of notes can follow also. */
283 || (GET_CODE (insn) == NOTE
284 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
285 insn = PREV_INSN (insn);
288 /* Report if control can fall through at the end of the function. */
289 if (insn && GET_CODE (insn) == NOTE
290 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
291 && ! INSN_DELETED_P (insn))
294 /* Zero the "deleted" flag of all the "deleted" insns. */
295 for (insn = f; insn; insn = NEXT_INSN (insn))
296 INSN_DELETED_P (insn) = 0;
303 /* If we fall through to the epilogue, see if we can insert a RETURN insn
304 in front of it. If the machine allows it at this point (we might be
305 after reload for a leaf routine), it will improve optimization for it
307 insn = get_last_insn ();
308 while (insn && GET_CODE (insn) == NOTE)
309 insn = PREV_INSN (insn);
311 if (insn && GET_CODE (insn) != BARRIER)
313 emit_jump_insn (gen_return ());
320 for (insn = f; insn; )
322 next = NEXT_INSN (insn);
324 if (GET_CODE (insn) == INSN)
326 register rtx body = PATTERN (insn);
328 /* Combine stack_adjusts with following push_insns. */
330 if (GET_CODE (body) == SET
331 && SET_DEST (body) == stack_pointer_rtx
332 && GET_CODE (SET_SRC (body)) == PLUS
333 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
334 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
335 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
338 rtx stack_adjust_insn = insn;
339 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
340 int total_pushed = 0;
343 /* Find all successive push insns. */
345 /* Don't convert more than three pushes;
346 that starts adding too many displaced addresses
347 and the whole thing starts becoming a losing
352 p = next_nonnote_insn (p);
353 if (p == 0 || GET_CODE (p) != INSN)
356 if (GET_CODE (pbody) != SET)
358 dest = SET_DEST (pbody);
359 /* Allow a no-op move between the adjust and the push. */
360 if (GET_CODE (dest) == REG
361 && GET_CODE (SET_SRC (pbody)) == REG
362 && REGNO (dest) == REGNO (SET_SRC (pbody)))
364 if (! (GET_CODE (dest) == MEM
365 && GET_CODE (XEXP (dest, 0)) == POST_INC
366 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
369 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
370 > stack_adjust_amount)
372 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
375 /* Discard the amount pushed from the stack adjust;
376 maybe eliminate it entirely. */
377 if (total_pushed >= stack_adjust_amount)
379 delete_computation (stack_adjust_insn);
380 total_pushed = stack_adjust_amount;
383 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
384 = GEN_INT (stack_adjust_amount - total_pushed);
386 /* Change the appropriate push insns to ordinary stores. */
388 while (total_pushed > 0)
391 p = next_nonnote_insn (p);
392 if (GET_CODE (p) != INSN)
395 if (GET_CODE (pbody) == SET)
397 dest = SET_DEST (pbody);
398 if (! (GET_CODE (dest) == MEM
399 && GET_CODE (XEXP (dest, 0)) == POST_INC
400 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
402 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
403 /* If this push doesn't fully fit in the space
404 of the stack adjust that we deleted,
405 make another stack adjust here for what we
406 didn't use up. There should be peepholes
407 to recognize the resulting sequence of insns. */
408 if (total_pushed < 0)
410 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
411 GEN_INT (- total_pushed)),
416 = plus_constant (stack_pointer_rtx, total_pushed);
421 /* Detect and delete no-op move instructions
422 resulting from not allocating a parameter in a register. */
424 if (GET_CODE (body) == SET
425 && (SET_DEST (body) == SET_SRC (body)
426 || (GET_CODE (SET_DEST (body)) == MEM
427 && GET_CODE (SET_SRC (body)) == MEM
428 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
429 && ! (GET_CODE (SET_DEST (body)) == MEM
430 && MEM_VOLATILE_P (SET_DEST (body)))
431 && ! (GET_CODE (SET_SRC (body)) == MEM
432 && MEM_VOLATILE_P (SET_SRC (body))))
433 delete_computation (insn);
435 /* Detect and ignore no-op move instructions
436 resulting from smart or fortuitous register allocation. */
438 else if (GET_CODE (body) == SET)
440 int sreg = true_regnum (SET_SRC (body));
441 int dreg = true_regnum (SET_DEST (body));
443 if (sreg == dreg && sreg >= 0)
445 else if (sreg >= 0 && dreg >= 0)
448 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
449 sreg, NULL_PTR, dreg,
450 GET_MODE (SET_SRC (body)));
452 #ifdef PRESERVE_DEATH_INFO_REGNO_P
453 /* Deleting insn could lose a death-note for SREG or DREG
454 so don't do it if final needs accurate death-notes. */
455 if (! PRESERVE_DEATH_INFO_REGNO_P (sreg)
456 && ! PRESERVE_DEATH_INFO_REGNO_P (dreg))
459 /* DREG may have been the target of a REG_DEAD note in
460 the insn which makes INSN redundant. If so, reorg
461 would still think it is dead. So search for such a
462 note and delete it if we find it. */
463 for (trial = prev_nonnote_insn (insn);
464 trial && GET_CODE (trial) != CODE_LABEL;
465 trial = prev_nonnote_insn (trial))
466 if (find_regno_note (trial, REG_DEAD, dreg))
468 remove_death (dreg, trial);
473 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
477 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
478 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
480 GET_MODE (SET_DEST (body))))
482 /* This handles the case where we have two consecutive
483 assignments of the same constant to pseudos that didn't
484 get a hard reg. Each SET from the constant will be
485 converted into a SET of the spill register and an
486 output reload will be made following it. This produces
487 two loads of the same constant into the same spill
492 /* Look back for a death note for the first reg.
493 If there is one, it is no longer accurate. */
494 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
496 if ((GET_CODE (in_insn) == INSN
497 || GET_CODE (in_insn) == JUMP_INSN)
498 && find_regno_note (in_insn, REG_DEAD, dreg))
500 remove_death (dreg, in_insn);
503 in_insn = PREV_INSN (in_insn);
506 /* Delete the second load of the value. */
510 else if (GET_CODE (body) == PARALLEL)
512 /* If each part is a set between two identical registers or
513 a USE or CLOBBER, delete the insn. */
517 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
519 tem = XVECEXP (body, 0, i);
520 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
523 if (GET_CODE (tem) != SET
524 || (sreg = true_regnum (SET_SRC (tem))) < 0
525 || (dreg = true_regnum (SET_DEST (tem))) < 0
533 /* Also delete insns to store bit fields if they are no-ops. */
534 /* Not worth the hair to detect this in the big-endian case. */
535 else if (! BYTES_BIG_ENDIAN
536 && GET_CODE (body) == SET
537 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
538 && XEXP (SET_DEST (body), 2) == const0_rtx
539 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
540 && ! (GET_CODE (SET_SRC (body)) == MEM
541 && MEM_VOLATILE_P (SET_SRC (body))))
547 /* If we haven't yet gotten to reload and we have just run regscan,
548 delete any insn that sets a register that isn't used elsewhere.
549 This helps some of the optimizations below by having less insns
550 being jumped around. */
552 if (! reload_completed && after_regscan)
553 for (insn = f; insn; insn = next)
555 rtx set = single_set (insn);
557 next = NEXT_INSN (insn);
559 if (set && GET_CODE (SET_DEST (set)) == REG
560 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
561 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
562 /* We use regno_last_note_uid so as not to delete the setting
563 of a reg that's used in notes. A subsequent optimization
564 might arrange to use that reg for real. */
565 && regno_last_note_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
566 && ! side_effects_p (SET_SRC (set))
567 && ! find_reg_note (insn, REG_RETVAL, 0))
571 /* Now iterate optimizing jumps until nothing changes over one pass. */
577 for (insn = f; insn; insn = next)
580 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
582 int this_is_simplejump, this_is_condjump, reversep;
583 int this_is_condjump_in_parallel;
585 /* If NOT the first iteration, if this is the last jump pass
586 (just before final), do the special peephole optimizations.
587 Avoiding the first iteration gives ordinary jump opts
588 a chance to work before peephole opts. */
590 if (reload_completed && !first && !flag_no_peephole)
591 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
595 /* That could have deleted some insns after INSN, so check now
596 what the following insn is. */
598 next = NEXT_INSN (insn);
600 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
601 jump. Try to optimize by duplicating the loop exit test if so.
602 This is only safe immediately after regscan, because it uses
603 the values of regno_first_uid and regno_last_uid. */
604 if (after_regscan && GET_CODE (insn) == NOTE
605 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
606 && (temp1 = next_nonnote_insn (insn)) != 0
607 && simplejump_p (temp1))
609 temp = PREV_INSN (insn);
610 if (duplicate_loop_exit_test (insn))
613 next = NEXT_INSN (temp);
618 if (GET_CODE (insn) != JUMP_INSN)
621 this_is_simplejump = simplejump_p (insn);
622 this_is_condjump = condjump_p (insn);
623 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
625 /* Tension the labels in dispatch tables. */
627 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
628 changed |= tension_vector_labels (PATTERN (insn), 0);
629 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
630 changed |= tension_vector_labels (PATTERN (insn), 1);
632 /* If a dispatch table always goes to the same place,
633 get rid of it and replace the insn that uses it. */
635 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
636 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
639 rtx pat = PATTERN (insn);
640 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
641 int len = XVECLEN (pat, diff_vec_p);
642 rtx dispatch = prev_real_insn (insn);
644 for (i = 0; i < len; i++)
645 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
646 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
650 && GET_CODE (dispatch) == JUMP_INSN
651 && JUMP_LABEL (dispatch) != 0
652 /* Don't mess with a casesi insn. */
653 && !(GET_CODE (PATTERN (dispatch)) == SET
654 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
656 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
658 redirect_tablejump (dispatch,
659 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
664 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
666 /* If a jump references the end of the function, try to turn
667 it into a RETURN insn, possibly a conditional one. */
668 if (JUMP_LABEL (insn)
669 && (next_active_insn (JUMP_LABEL (insn)) == 0
670 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
672 changed |= redirect_jump (insn, NULL_RTX);
674 /* Detect jump to following insn. */
675 if (reallabelprev == insn && condjump_p (insn))
677 next = next_real_insn (JUMP_LABEL (insn));
683 /* If we have an unconditional jump preceded by a USE, try to put
684 the USE before the target and jump there. This simplifies many
685 of the optimizations below since we don't have to worry about
686 dealing with these USE insns. We only do this if the label
687 being branch to already has the identical USE or if code
688 never falls through to that label. */
690 if (this_is_simplejump
691 && (temp = prev_nonnote_insn (insn)) != 0
692 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
693 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
694 && (GET_CODE (temp1) == BARRIER
695 || (GET_CODE (temp1) == INSN
696 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
697 /* Don't do this optimization if we have a loop containing only
698 the USE instruction, and the loop start label has a usage
699 count of 1. This is because we will redo this optimization
700 everytime through the outer loop, and jump opt will never
702 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
703 && temp2 == JUMP_LABEL (insn)
704 && LABEL_NUSES (temp2) == 1))
706 if (GET_CODE (temp1) == BARRIER)
708 emit_insn_after (PATTERN (temp), temp1);
709 temp1 = NEXT_INSN (temp1);
713 redirect_jump (insn, get_label_before (temp1));
714 reallabelprev = prev_real_insn (temp1);
718 /* Simplify if (...) x = a; else x = b; by converting it
719 to x = b; if (...) x = a;
720 if B is sufficiently simple, the test doesn't involve X,
721 and nothing in the test modifies B or X.
723 If we have small register classes, we also can't do this if X
726 If the "x = b;" insn has any REG_NOTES, we don't do this because
727 of the possibility that we are running after CSE and there is a
728 REG_EQUAL note that is only valid if the branch has already been
729 taken. If we move the insn with the REG_EQUAL note, we may
730 fold the comparison to always be false in a later CSE pass.
731 (We could also delete the REG_NOTES when moving the insn, but it
732 seems simpler to not move it.) An exception is that we can move
733 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
734 value is the same as "b".
736 INSN is the branch over the `else' part.
740 TEMP to the jump insn preceding "x = a;"
742 TEMP2 to the insn that sets "x = b;"
743 TEMP3 to the insn that sets "x = a;"
744 TEMP4 to the set of "x = b"; */
746 if (this_is_simplejump
747 && (temp3 = prev_active_insn (insn)) != 0
748 && GET_CODE (temp3) == INSN
749 && (temp4 = single_set (temp3)) != 0
750 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
751 #ifdef SMALL_REGISTER_CLASSES
752 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
754 && (temp2 = next_active_insn (insn)) != 0
755 && GET_CODE (temp2) == INSN
756 && (temp4 = single_set (temp2)) != 0
757 && rtx_equal_p (SET_DEST (temp4), temp1)
758 && (GET_CODE (SET_SRC (temp4)) == REG
759 || GET_CODE (SET_SRC (temp4)) == SUBREG
760 || CONSTANT_P (SET_SRC (temp4)))
761 && (REG_NOTES (temp2) == 0
762 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
763 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
764 && XEXP (REG_NOTES (temp2), 1) == 0
765 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
767 && (temp = prev_active_insn (temp3)) != 0
768 && condjump_p (temp) && ! simplejump_p (temp)
769 /* TEMP must skip over the "x = a;" insn */
770 && prev_real_insn (JUMP_LABEL (temp)) == insn
771 && no_labels_between_p (insn, JUMP_LABEL (temp))
772 /* There must be no other entries to the "x = b;" insn. */
773 && no_labels_between_p (JUMP_LABEL (temp), temp2)
774 /* INSN must either branch to the insn after TEMP2 or the insn
775 after TEMP2 must branch to the same place as INSN. */
776 && (reallabelprev == temp2
777 || ((temp5 = next_active_insn (temp2)) != 0
778 && simplejump_p (temp5)
779 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
781 /* The test expression, X, may be a complicated test with
782 multiple branches. See if we can find all the uses of
783 the label that TEMP branches to without hitting a CALL_INSN
784 or a jump to somewhere else. */
785 rtx target = JUMP_LABEL (temp);
786 int nuses = LABEL_NUSES (target);
789 /* Set P to the first jump insn that goes around "x = a;". */
790 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
792 if (GET_CODE (p) == JUMP_INSN)
794 if (condjump_p (p) && ! simplejump_p (p)
795 && JUMP_LABEL (p) == target)
804 else if (GET_CODE (p) == CALL_INSN)
809 /* We cannot insert anything between a set of cc and its use
810 so if P uses cc0, we must back up to the previous insn. */
811 q = prev_nonnote_insn (p);
812 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
813 && sets_cc0_p (PATTERN (q)))
820 /* If we found all the uses and there was no data conflict, we
821 can move the assignment unless we can branch into the middle
824 && no_labels_between_p (p, insn)
825 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
826 && ! reg_set_between_p (temp1, p, temp3)
827 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
828 || ! reg_set_between_p (SET_SRC (temp4), p, temp2)))
830 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
833 /* Set NEXT to an insn that we know won't go away. */
834 next = next_active_insn (insn);
836 /* Delete the jump around the set. Note that we must do
837 this before we redirect the test jumps so that it won't
838 delete the code immediately following the assignment
839 we moved (which might be a jump). */
843 /* We either have two consecutive labels or a jump to
844 a jump, so adjust all the JUMP_INSNs to branch to where
846 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
847 if (GET_CODE (p) == JUMP_INSN)
848 redirect_jump (p, target);
856 /* If we have if (...) x = exp; and branches are expensive,
857 EXP is a single insn, does not have any side effects, cannot
858 trap, and is not too costly, convert this to
859 t = exp; if (...) x = t;
861 Don't do this when we have CC0 because it is unlikely to help
862 and we'd need to worry about where to place the new insn and
863 the potential for conflicts. We also can't do this when we have
864 notes on the insn for the same reason as above.
868 TEMP to the "x = exp;" insn.
869 TEMP1 to the single set in the "x = exp; insn.
872 if (! reload_completed
873 && this_is_condjump && ! this_is_simplejump
875 && (temp = next_nonnote_insn (insn)) != 0
876 && GET_CODE (temp) == INSN
877 && REG_NOTES (temp) == 0
878 && (reallabelprev == temp
879 || ((temp2 = next_active_insn (temp)) != 0
880 && simplejump_p (temp2)
881 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
882 && (temp1 = single_set (temp)) != 0
883 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
884 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
885 #ifdef SMALL_REGISTER_CLASSES
886 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
888 && GET_CODE (SET_SRC (temp1)) != REG
889 && GET_CODE (SET_SRC (temp1)) != SUBREG
890 && GET_CODE (SET_SRC (temp1)) != CONST_INT
891 && ! side_effects_p (SET_SRC (temp1))
892 && ! may_trap_p (SET_SRC (temp1))
893 && rtx_cost (SET_SRC (temp1), SET) < 10)
895 rtx new = gen_reg_rtx (GET_MODE (temp2));
897 if (validate_change (temp, &SET_DEST (temp1), new, 0))
899 next = emit_insn_after (gen_move_insn (temp2, new), insn);
900 emit_insn_after_with_line_notes (PATTERN (temp),
901 PREV_INSN (insn), temp);
903 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
907 /* Similarly, if it takes two insns to compute EXP but they
908 have the same destination. Here TEMP3 will be the second
909 insn and TEMP4 the SET from that insn. */
911 if (! reload_completed
912 && this_is_condjump && ! this_is_simplejump
914 && (temp = next_nonnote_insn (insn)) != 0
915 && GET_CODE (temp) == INSN
916 && REG_NOTES (temp) == 0
917 && (temp3 = next_nonnote_insn (temp)) != 0
918 && GET_CODE (temp3) == INSN
919 && REG_NOTES (temp3) == 0
920 && (reallabelprev == temp3
921 || ((temp2 = next_active_insn (temp3)) != 0
922 && simplejump_p (temp2)
923 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
924 && (temp1 = single_set (temp)) != 0
925 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
926 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
927 #ifdef SMALL_REGISTER_CLASSES
928 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
930 && ! side_effects_p (SET_SRC (temp1))
931 && ! may_trap_p (SET_SRC (temp1))
932 && rtx_cost (SET_SRC (temp1), SET) < 10
933 && (temp4 = single_set (temp3)) != 0
934 && rtx_equal_p (SET_DEST (temp4), temp2)
935 && ! side_effects_p (SET_SRC (temp4))
936 && ! may_trap_p (SET_SRC (temp4))
937 && rtx_cost (SET_SRC (temp4), SET) < 10)
939 rtx new = gen_reg_rtx (GET_MODE (temp2));
941 if (validate_change (temp, &SET_DEST (temp1), new, 0))
943 next = emit_insn_after (gen_move_insn (temp2, new), insn);
944 emit_insn_after_with_line_notes (PATTERN (temp),
945 PREV_INSN (insn), temp);
946 emit_insn_after_with_line_notes
947 (replace_rtx (PATTERN (temp3), temp2, new),
948 PREV_INSN (insn), temp3);
951 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
955 /* Finally, handle the case where two insns are used to
956 compute EXP but a temporary register is used. Here we must
957 ensure that the temporary register is not used anywhere else. */
959 if (! reload_completed
961 && this_is_condjump && ! this_is_simplejump
963 && (temp = next_nonnote_insn (insn)) != 0
964 && GET_CODE (temp) == INSN
965 && REG_NOTES (temp) == 0
966 && (temp3 = next_nonnote_insn (temp)) != 0
967 && GET_CODE (temp3) == INSN
968 && REG_NOTES (temp3) == 0
969 && (reallabelprev == temp3
970 || ((temp2 = next_active_insn (temp3)) != 0
971 && simplejump_p (temp2)
972 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
973 && (temp1 = single_set (temp)) != 0
974 && (temp5 = SET_DEST (temp1),
975 (GET_CODE (temp5) == REG
976 || (GET_CODE (temp5) == SUBREG
977 && (temp5 = SUBREG_REG (temp5),
978 GET_CODE (temp5) == REG))))
979 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
980 && regno_first_uid[REGNO (temp5)] == INSN_UID (temp)
981 && regno_last_uid[REGNO (temp5)] == INSN_UID (temp3)
982 && ! side_effects_p (SET_SRC (temp1))
983 && ! may_trap_p (SET_SRC (temp1))
984 && rtx_cost (SET_SRC (temp1), SET) < 10
985 && (temp4 = single_set (temp3)) != 0
986 && (temp2 = SET_DEST (temp4), 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 && rtx_equal_p (SET_DEST (temp4), temp2)
992 && ! side_effects_p (SET_SRC (temp4))
993 && ! may_trap_p (SET_SRC (temp4))
994 && rtx_cost (SET_SRC (temp4), SET) < 10)
996 rtx new = gen_reg_rtx (GET_MODE (temp2));
998 if (validate_change (temp3, &SET_DEST (temp4), new, 0))
1000 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1001 emit_insn_after_with_line_notes (PATTERN (temp),
1002 PREV_INSN (insn), temp);
1003 emit_insn_after_with_line_notes (PATTERN (temp3),
1004 PREV_INSN (insn), temp3);
1006 delete_insn (temp3);
1007 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1010 #endif /* HAVE_cc0 */
1012 /* Try to use a conditional move (if the target has them), or a
1013 store-flag insn. The general case is:
1015 1) x = a; if (...) x = b; and
1018 If the jump would be faster, the machine should not have defined
1019 the movcc or scc insns!. These cases are often made by the
1020 previous optimization.
1022 The second case is treated as x = x; if (...) x = b;.
1024 INSN here is the jump around the store. We set:
1026 TEMP to the "x = b;" insn.
1029 TEMP3 to A (X in the second case).
1030 TEMP4 to the condition being tested.
1031 TEMP5 to the earliest insn used to find the condition. */
1033 if (/* We can't do this after reload has completed. */
1035 && this_is_condjump && ! this_is_simplejump
1036 /* Set TEMP to the "x = b;" insn. */
1037 && (temp = next_nonnote_insn (insn)) != 0
1038 && GET_CODE (temp) == INSN
1039 && GET_CODE (PATTERN (temp)) == SET
1040 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1041 #ifdef SMALL_REGISTER_CLASSES
1042 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
1044 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1045 || GET_CODE (temp2) == SUBREG
1046 /* ??? How about floating point constants? */
1047 || GET_CODE (temp2) == CONST_INT)
1048 /* Allow either form, but prefer the former if both apply.
1049 There is no point in using the old value of TEMP1 if
1050 it is a register, since cse will alias them. It can
1051 lose if the old value were a hard register since CSE
1052 won't replace hard registers. */
1053 && (((temp3 = reg_set_last (temp1, insn)) != 0)
1054 /* Make the latter case look like x = x; if (...) x = b; */
1055 || (temp3 = temp1, 1))
1056 /* INSN must either branch to the insn after TEMP or the insn
1057 after TEMP must branch to the same place as INSN. */
1058 && (reallabelprev == temp
1059 || ((temp4 = next_active_insn (temp)) != 0
1060 && simplejump_p (temp4)
1061 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1062 && (temp4 = get_condition (insn, &temp5)) != 0
1063 /* We must be comparing objects whose modes imply the size.
1064 We could handle BLKmode if (1) emit_store_flag could
1065 and (2) we could find the size reliably. */
1066 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1067 /* No point in doing any of this if branches are cheap or we
1068 don't have conditional moves. */
1069 && (BRANCH_COST >= 2
1070 #ifdef HAVE_conditional_move
1075 /* If the previous insn sets CC0 and something else, we can't
1076 do this since we are going to delete that insn. */
1078 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1079 && GET_CODE (temp6) == INSN
1080 && (sets_cc0_p (PATTERN (temp6)) == -1
1081 || (sets_cc0_p (PATTERN (temp6)) == 1
1082 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1086 #ifdef HAVE_conditional_move
1087 /* First try a conditional move. */
1089 enum rtx_code code = GET_CODE (temp4);
1091 rtx cond0, cond1, aval, bval;
1094 /* Copy the compared variables into cond0 and cond1, so that
1095 any side effects performed in or after the old comparison,
1096 will not affect our compare which will come later. */
1097 /* ??? Is it possible to just use the comparison in the jump
1098 insn? After all, we're going to delete it. We'd have
1099 to modify emit_conditional_move to take a comparison rtx
1100 instead or write a new function. */
1101 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1102 /* We want the target to be able to simplify comparisons with
1103 zero (and maybe other constants as well), so don't create
1104 pseudos for them. There's no need to either. */
1105 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1106 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1107 cond1 = XEXP (temp4, 1);
1109 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1115 target = emit_conditional_move (var, code,
1116 cond0, cond1, VOIDmode,
1117 aval, bval, GET_MODE (var),
1118 (code == LTU || code == GEU
1119 || code == LEU || code == GTU));
1125 /* Save the conditional move sequence but don't emit it
1126 yet. On some machines, like the alpha, it is possible
1127 that temp5 == insn, so next generate the sequence that
1128 saves the compared values and then emit both
1129 sequences ensuring seq1 occurs before seq2. */
1130 seq2 = get_insns ();
1133 /* Now that we can't fail, generate the copy insns that
1134 preserve the compared values. */
1136 emit_move_insn (cond0, XEXP (temp4, 0));
1137 if (cond1 != XEXP (temp4, 1))
1138 emit_move_insn (cond1, XEXP (temp4, 1));
1139 seq1 = get_insns ();
1142 emit_insns_before (seq1, temp5);
1143 /* Insert conditional move after insn, to be sure that
1144 the jump and a possible compare won't be separated */
1145 emit_insns_after (seq2, insn);
1147 /* ??? We can also delete the insn that sets X to A.
1148 Flow will do it too though. */
1150 next = NEXT_INSN (insn);
1160 /* That didn't work, try a store-flag insn.
1162 We further divide the cases into:
1164 1) x = a; if (...) x = b; and either A or B is zero,
1165 2) if (...) x = 0; and jumps are expensive,
1166 3) x = a; if (...) x = b; and A and B are constants where all
1167 the set bits in A are also set in B and jumps are expensive,
1168 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1170 5) if (...) x = b; if jumps are even more expensive. */
1172 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1173 && ((GET_CODE (temp3) == CONST_INT)
1174 /* Make the latter case look like
1175 x = x; if (...) x = 0; */
1178 && temp2 == const0_rtx)
1179 || BRANCH_COST >= 3)))
1180 /* If B is zero, OK; if A is zero, can only do (1) if we
1181 can reverse the condition. See if (3) applies possibly
1182 by reversing the condition. Prefer reversing to (4) when
1183 branches are very expensive. */
1184 && ((reversep = 0, temp2 == const0_rtx)
1185 || (temp3 == const0_rtx
1186 && (reversep = can_reverse_comparison_p (temp4, insn)))
1187 || (BRANCH_COST >= 2
1188 && GET_CODE (temp2) == CONST_INT
1189 && GET_CODE (temp3) == CONST_INT
1190 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1191 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1192 && (reversep = can_reverse_comparison_p (temp4,
1194 || BRANCH_COST >= 3)
1197 enum rtx_code code = GET_CODE (temp4);
1198 rtx uval, cval, var = temp1;
1202 /* If necessary, reverse the condition. */
1204 code = reverse_condition (code), uval = temp2, cval = temp3;
1206 uval = temp3, cval = temp2;
1208 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1209 is the constant 1, it is best to just compute the result
1210 directly. If UVAL is constant and STORE_FLAG_VALUE
1211 includes all of its bits, it is best to compute the flag
1212 value unnormalized and `and' it with UVAL. Otherwise,
1213 normalize to -1 and `and' with UVAL. */
1214 normalizep = (cval != const0_rtx ? -1
1215 : (uval == const1_rtx ? 1
1216 : (GET_CODE (uval) == CONST_INT
1217 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1220 /* We will be putting the store-flag insn immediately in
1221 front of the comparison that was originally being done,
1222 so we know all the variables in TEMP4 will be valid.
1223 However, this might be in front of the assignment of
1224 A to VAR. If it is, it would clobber the store-flag
1225 we will be emitting.
1227 Therefore, emit into a temporary which will be copied to
1228 VAR immediately after TEMP. */
1231 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1232 XEXP (temp4, 0), XEXP (temp4, 1),
1234 (code == LTU || code == LEU
1235 || code == GEU || code == GTU),
1245 /* Put the store-flag insns in front of the first insn
1246 used to compute the condition to ensure that we
1247 use the same values of them as the current
1248 comparison. However, the remainder of the insns we
1249 generate will be placed directly in front of the
1250 jump insn, in case any of the pseudos we use
1251 are modified earlier. */
1253 emit_insns_before (seq, temp5);
1257 /* Both CVAL and UVAL are non-zero. */
1258 if (cval != const0_rtx && uval != const0_rtx)
1262 tem1 = expand_and (uval, target, NULL_RTX);
1263 if (GET_CODE (cval) == CONST_INT
1264 && GET_CODE (uval) == CONST_INT
1265 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1269 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1270 target, NULL_RTX, 0);
1271 tem2 = expand_and (cval, tem2,
1272 (GET_CODE (tem2) == REG
1276 /* If we usually make new pseudos, do so here. This
1277 turns out to help machines that have conditional
1279 /* ??? Conditional moves have already been handled.
1280 This may be obsolete. */
1282 if (flag_expensive_optimizations)
1285 target = expand_binop (GET_MODE (var), ior_optab,
1289 else if (normalizep != 1)
1291 /* We know that either CVAL or UVAL is zero. If
1292 UVAL is zero, negate TARGET and `and' with CVAL.
1293 Otherwise, `and' with UVAL. */
1294 if (uval == const0_rtx)
1296 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1297 target, NULL_RTX, 0);
1301 target = expand_and (uval, target,
1302 (GET_CODE (target) == REG
1303 && ! preserve_subexpressions_p ()
1304 ? target : NULL_RTX));
1307 emit_move_insn (var, target);
1311 /* If INSN uses CC0, we must not separate it from the
1312 insn that sets cc0. */
1313 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1314 before = prev_nonnote_insn (before);
1316 emit_insns_before (seq, before);
1319 next = NEXT_INSN (insn);
1329 /* If branches are expensive, convert
1330 if (foo) bar++; to bar += (foo != 0);
1331 and similarly for "bar--;"
1333 INSN is the conditional branch around the arithmetic. We set:
1335 TEMP is the arithmetic insn.
1336 TEMP1 is the SET doing the arithmetic.
1337 TEMP2 is the operand being incremented or decremented.
1338 TEMP3 to the condition being tested.
1339 TEMP4 to the earliest insn used to find the condition. */
1341 if ((BRANCH_COST >= 2
1349 && ! reload_completed
1350 && this_is_condjump && ! this_is_simplejump
1351 && (temp = next_nonnote_insn (insn)) != 0
1352 && (temp1 = single_set (temp)) != 0
1353 && (temp2 = SET_DEST (temp1),
1354 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1355 && GET_CODE (SET_SRC (temp1)) == PLUS
1356 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1357 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1358 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1359 && ! side_effects_p (temp2)
1360 && ! may_trap_p (temp2)
1361 /* INSN must either branch to the insn after TEMP or the insn
1362 after TEMP must branch to the same place as INSN. */
1363 && (reallabelprev == temp
1364 || ((temp3 = next_active_insn (temp)) != 0
1365 && simplejump_p (temp3)
1366 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1367 && (temp3 = get_condition (insn, &temp4)) != 0
1368 /* We must be comparing objects whose modes imply the size.
1369 We could handle BLKmode if (1) emit_store_flag could
1370 and (2) we could find the size reliably. */
1371 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1372 && can_reverse_comparison_p (temp3, insn))
1374 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1375 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1379 /* It must be the case that TEMP2 is not modified in the range
1380 [TEMP4, INSN). The one exception we make is if the insn
1381 before INSN sets TEMP2 to something which is also unchanged
1382 in that range. In that case, we can move the initialization
1383 into our sequence. */
1385 if ((temp5 = prev_active_insn (insn)) != 0
1386 && GET_CODE (temp5) == INSN
1387 && (temp6 = single_set (temp5)) != 0
1388 && rtx_equal_p (temp2, SET_DEST (temp6))
1389 && (CONSTANT_P (SET_SRC (temp6))
1390 || GET_CODE (SET_SRC (temp6)) == REG
1391 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1393 emit_insn (PATTERN (temp5));
1395 init = SET_SRC (temp6);
1398 if (CONSTANT_P (init)
1399 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1400 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1401 XEXP (temp3, 0), XEXP (temp3, 1),
1403 (code == LTU || code == LEU
1404 || code == GTU || code == GEU), 1);
1406 /* If we can do the store-flag, do the addition or
1410 target = expand_binop (GET_MODE (temp2),
1411 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1412 ? add_optab : sub_optab),
1413 temp2, target, temp2, 0, OPTAB_WIDEN);
1417 /* Put the result back in temp2 in case it isn't already.
1418 Then replace the jump, possible a CC0-setting insn in
1419 front of the jump, and TEMP, with the sequence we have
1422 if (target != temp2)
1423 emit_move_insn (temp2, target);
1428 emit_insns_before (seq, temp4);
1432 delete_insn (init_insn);
1434 next = NEXT_INSN (insn);
1436 delete_insn (prev_nonnote_insn (insn));
1446 /* Simplify if (...) x = 1; else {...} if (x) ...
1447 We recognize this case scanning backwards as well.
1449 TEMP is the assignment to x;
1450 TEMP1 is the label at the head of the second if. */
1451 /* ?? This should call get_condition to find the values being
1452 compared, instead of looking for a COMPARE insn when HAVE_cc0
1453 is not defined. This would allow it to work on the m88k. */
1454 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1455 is not defined and the condition is tested by a separate compare
1456 insn. This is because the code below assumes that the result
1457 of the compare dies in the following branch.
1459 Not only that, but there might be other insns between the
1460 compare and branch whose results are live. Those insns need
1463 A way to fix this is to move the insns at JUMP_LABEL (insn)
1464 to before INSN. If we are running before flow, they will
1465 be deleted if they aren't needed. But this doesn't work
1468 This is really a special-case of jump threading, anyway. The
1469 right thing to do is to replace this and jump threading with
1470 much simpler code in cse.
1472 This code has been turned off in the non-cc0 case in the
1476 else if (this_is_simplejump
1477 /* Safe to skip USE and CLOBBER insns here
1478 since they will not be deleted. */
1479 && (temp = prev_active_insn (insn))
1480 && no_labels_between_p (temp, insn)
1481 && GET_CODE (temp) == INSN
1482 && GET_CODE (PATTERN (temp)) == SET
1483 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1484 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1485 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1486 /* If we find that the next value tested is `x'
1487 (TEMP1 is the insn where this happens), win. */
1488 && GET_CODE (temp1) == INSN
1489 && GET_CODE (PATTERN (temp1)) == SET
1491 /* Does temp1 `tst' the value of x? */
1492 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1493 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1494 && (temp1 = next_nonnote_insn (temp1))
1496 /* Does temp1 compare the value of x against zero? */
1497 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1498 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1499 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1500 == SET_DEST (PATTERN (temp)))
1501 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1502 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1504 && condjump_p (temp1))
1506 /* Get the if_then_else from the condjump. */
1507 rtx choice = SET_SRC (PATTERN (temp1));
1508 if (GET_CODE (choice) == IF_THEN_ELSE)
1510 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1511 rtx val = SET_SRC (PATTERN (temp));
1513 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1517 if (cond == const_true_rtx)
1518 ultimate = XEXP (choice, 1);
1519 else if (cond == const0_rtx)
1520 ultimate = XEXP (choice, 2);
1524 if (ultimate == pc_rtx)
1525 ultimate = get_label_after (temp1);
1526 else if (ultimate && GET_CODE (ultimate) != RETURN)
1527 ultimate = XEXP (ultimate, 0);
1529 if (ultimate && JUMP_LABEL(insn) != ultimate)
1530 changed |= redirect_jump (insn, ultimate);
1536 /* @@ This needs a bit of work before it will be right.
1538 Any type of comparison can be accepted for the first and
1539 second compare. When rewriting the first jump, we must
1540 compute the what conditions can reach label3, and use the
1541 appropriate code. We can not simply reverse/swap the code
1542 of the first jump. In some cases, the second jump must be
1546 < == converts to > ==
1547 < != converts to == >
1550 If the code is written to only accept an '==' test for the second
1551 compare, then all that needs to be done is to swap the condition
1552 of the first branch.
1554 It is questionable whether we want this optimization anyways,
1555 since if the user wrote code like this because he/she knew that
1556 the jump to label1 is taken most of the time, then rewriting
1557 this gives slower code. */
1558 /* @@ This should call get_condition to find the values being
1559 compared, instead of looking for a COMPARE insn when HAVE_cc0
1560 is not defined. This would allow it to work on the m88k. */
1561 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1562 is not defined and the condition is tested by a separate compare
1563 insn. This is because the code below assumes that the result
1564 of the compare dies in the following branch. */
1566 /* Simplify test a ~= b
1580 where ~= is an inequality, e.g. >, and ~~= is the swapped
1583 We recognize this case scanning backwards.
1585 TEMP is the conditional jump to `label2';
1586 TEMP1 is the test for `a == b';
1587 TEMP2 is the conditional jump to `label1';
1588 TEMP3 is the test for `a ~= b'. */
1589 else if (this_is_simplejump
1590 && (temp = prev_active_insn (insn))
1591 && no_labels_between_p (temp, insn)
1592 && condjump_p (temp)
1593 && (temp1 = prev_active_insn (temp))
1594 && no_labels_between_p (temp1, temp)
1595 && GET_CODE (temp1) == INSN
1596 && GET_CODE (PATTERN (temp1)) == SET
1598 && sets_cc0_p (PATTERN (temp1)) == 1
1600 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1601 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1602 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1604 && (temp2 = prev_active_insn (temp1))
1605 && no_labels_between_p (temp2, temp1)
1606 && condjump_p (temp2)
1607 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1608 && (temp3 = prev_active_insn (temp2))
1609 && no_labels_between_p (temp3, temp2)
1610 && GET_CODE (PATTERN (temp3)) == SET
1611 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1612 SET_DEST (PATTERN (temp1)))
1613 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1614 SET_SRC (PATTERN (temp3)))
1615 && ! inequality_comparisons_p (PATTERN (temp))
1616 && inequality_comparisons_p (PATTERN (temp2)))
1618 rtx fallthrough_label = JUMP_LABEL (temp2);
1620 ++LABEL_NUSES (fallthrough_label);
1621 if (swap_jump (temp2, JUMP_LABEL (insn)))
1627 if (--LABEL_NUSES (fallthrough_label) == 0)
1628 delete_insn (fallthrough_label);
1631 /* Simplify if (...) {... x = 1;} if (x) ...
1633 We recognize this case backwards.
1635 TEMP is the test of `x';
1636 TEMP1 is the assignment to `x' at the end of the
1637 previous statement. */
1638 /* @@ This should call get_condition to find the values being
1639 compared, instead of looking for a COMPARE insn when HAVE_cc0
1640 is not defined. This would allow it to work on the m88k. */
1641 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1642 is not defined and the condition is tested by a separate compare
1643 insn. This is because the code below assumes that the result
1644 of the compare dies in the following branch. */
1646 /* ??? This has to be turned off. The problem is that the
1647 unconditional jump might indirectly end up branching to the
1648 label between TEMP1 and TEMP. We can't detect this, in general,
1649 since it may become a jump to there after further optimizations.
1650 If that jump is done, it will be deleted, so we will retry
1651 this optimization in the next pass, thus an infinite loop.
1653 The present code prevents this by putting the jump after the
1654 label, but this is not logically correct. */
1656 else if (this_is_condjump
1657 /* Safe to skip USE and CLOBBER insns here
1658 since they will not be deleted. */
1659 && (temp = prev_active_insn (insn))
1660 && no_labels_between_p (temp, insn)
1661 && GET_CODE (temp) == INSN
1662 && GET_CODE (PATTERN (temp)) == SET
1664 && sets_cc0_p (PATTERN (temp)) == 1
1665 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1667 /* Temp must be a compare insn, we can not accept a register
1668 to register move here, since it may not be simply a
1670 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1671 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1672 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1673 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1674 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1676 /* May skip USE or CLOBBER insns here
1677 for checking for opportunity, since we
1678 take care of them later. */
1679 && (temp1 = prev_active_insn (temp))
1680 && GET_CODE (temp1) == INSN
1681 && GET_CODE (PATTERN (temp1)) == SET
1683 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1685 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1686 == SET_DEST (PATTERN (temp1)))
1688 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1689 /* If this isn't true, cse will do the job. */
1690 && ! no_labels_between_p (temp1, temp))
1692 /* Get the if_then_else from the condjump. */
1693 rtx choice = SET_SRC (PATTERN (insn));
1694 if (GET_CODE (choice) == IF_THEN_ELSE
1695 && (GET_CODE (XEXP (choice, 0)) == EQ
1696 || GET_CODE (XEXP (choice, 0)) == NE))
1698 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1703 /* Get the place that condjump will jump to
1704 if it is reached from here. */
1705 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1707 ultimate = XEXP (choice, 1);
1709 ultimate = XEXP (choice, 2);
1710 /* Get it as a CODE_LABEL. */
1711 if (ultimate == pc_rtx)
1712 ultimate = get_label_after (insn);
1714 /* Get the label out of the LABEL_REF. */
1715 ultimate = XEXP (ultimate, 0);
1717 /* Insert the jump immediately before TEMP, specifically
1718 after the label that is between TEMP1 and TEMP. */
1719 last_insn = PREV_INSN (temp);
1721 /* If we would be branching to the next insn, the jump
1722 would immediately be deleted and the re-inserted in
1723 a subsequent pass over the code. So don't do anything
1725 if (next_active_insn (last_insn)
1726 != next_active_insn (ultimate))
1728 emit_barrier_after (last_insn);
1729 p = emit_jump_insn_after (gen_jump (ultimate),
1731 JUMP_LABEL (p) = ultimate;
1732 ++LABEL_NUSES (ultimate);
1733 if (INSN_UID (ultimate) < max_jump_chain
1734 && INSN_CODE (p) < max_jump_chain)
1736 jump_chain[INSN_UID (p)]
1737 = jump_chain[INSN_UID (ultimate)];
1738 jump_chain[INSN_UID (ultimate)] = p;
1746 /* Detect a conditional jump going to the same place
1747 as an immediately following unconditional jump. */
1748 else if (this_is_condjump
1749 && (temp = next_active_insn (insn)) != 0
1750 && simplejump_p (temp)
1751 && (next_active_insn (JUMP_LABEL (insn))
1752 == next_active_insn (JUMP_LABEL (temp))))
1758 /* Detect a conditional jump jumping over an unconditional jump. */
1760 else if ((this_is_condjump || this_is_condjump_in_parallel)
1761 && ! this_is_simplejump
1762 && reallabelprev != 0
1763 && GET_CODE (reallabelprev) == JUMP_INSN
1764 && prev_active_insn (reallabelprev) == insn
1765 && no_labels_between_p (insn, reallabelprev)
1766 && simplejump_p (reallabelprev))
1768 /* When we invert the unconditional jump, we will be
1769 decrementing the usage count of its old label.
1770 Make sure that we don't delete it now because that
1771 might cause the following code to be deleted. */
1772 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1773 rtx prev_label = JUMP_LABEL (insn);
1776 ++LABEL_NUSES (prev_label);
1778 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1780 /* It is very likely that if there are USE insns before
1781 this jump, they hold REG_DEAD notes. These REG_DEAD
1782 notes are no longer valid due to this optimization,
1783 and will cause the life-analysis that following passes
1784 (notably delayed-branch scheduling) to think that
1785 these registers are dead when they are not.
1787 To prevent this trouble, we just remove the USE insns
1788 from the insn chain. */
1790 while (prev_uses && GET_CODE (prev_uses) == INSN
1791 && GET_CODE (PATTERN (prev_uses)) == USE)
1793 rtx useless = prev_uses;
1794 prev_uses = prev_nonnote_insn (prev_uses);
1795 delete_insn (useless);
1798 delete_insn (reallabelprev);
1803 /* We can now safely delete the label if it is unreferenced
1804 since the delete_insn above has deleted the BARRIER. */
1805 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1806 delete_insn (prev_label);
1811 /* Detect a jump to a jump. */
1813 nlabel = follow_jumps (JUMP_LABEL (insn));
1814 if (nlabel != JUMP_LABEL (insn)
1815 && redirect_jump (insn, nlabel))
1821 /* Look for if (foo) bar; else break; */
1822 /* The insns look like this:
1823 insn = condjump label1;
1824 ...range1 (some insns)...
1827 ...range2 (some insns)...
1828 jump somewhere unconditionally
1831 rtx label1 = next_label (insn);
1832 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1833 /* Don't do this optimization on the first round, so that
1834 jump-around-a-jump gets simplified before we ask here
1835 whether a jump is unconditional.
1837 Also don't do it when we are called after reload since
1838 it will confuse reorg. */
1840 && (reload_completed ? ! flag_delayed_branch : 1)
1841 /* Make sure INSN is something we can invert. */
1842 && condjump_p (insn)
1844 && JUMP_LABEL (insn) == label1
1845 && LABEL_NUSES (label1) == 1
1846 && GET_CODE (range1end) == JUMP_INSN
1847 && simplejump_p (range1end))
1849 rtx label2 = next_label (label1);
1850 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1851 if (range1end != range2end
1852 && JUMP_LABEL (range1end) == label2
1853 && GET_CODE (range2end) == JUMP_INSN
1854 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1855 /* Invert the jump condition, so we
1856 still execute the same insns in each case. */
1857 && invert_jump (insn, label1))
1859 rtx range1beg = next_active_insn (insn);
1860 rtx range2beg = next_active_insn (label1);
1861 rtx range1after, range2after;
1862 rtx range1before, range2before;
1865 /* Include in each range any notes before it, to be
1866 sure that we get the line number note if any, even
1867 if there are other notes here. */
1868 while (PREV_INSN (range1beg)
1869 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1870 range1beg = PREV_INSN (range1beg);
1872 while (PREV_INSN (range2beg)
1873 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1874 range2beg = PREV_INSN (range2beg);
1876 /* Don't move NOTEs for blocks or loops; shift them
1877 outside the ranges, where they'll stay put. */
1878 range1beg = squeeze_notes (range1beg, range1end);
1879 range2beg = squeeze_notes (range2beg, range2end);
1881 /* Get current surrounds of the 2 ranges. */
1882 range1before = PREV_INSN (range1beg);
1883 range2before = PREV_INSN (range2beg);
1884 range1after = NEXT_INSN (range1end);
1885 range2after = NEXT_INSN (range2end);
1887 /* Splice range2 where range1 was. */
1888 NEXT_INSN (range1before) = range2beg;
1889 PREV_INSN (range2beg) = range1before;
1890 NEXT_INSN (range2end) = range1after;
1891 PREV_INSN (range1after) = range2end;
1892 /* Splice range1 where range2 was. */
1893 NEXT_INSN (range2before) = range1beg;
1894 PREV_INSN (range1beg) = range2before;
1895 NEXT_INSN (range1end) = range2after;
1896 PREV_INSN (range2after) = range1end;
1898 /* Check for a loop end note between the end of
1899 range2, and the next code label. If there is one,
1900 then what we have really seen is
1901 if (foo) break; end_of_loop;
1902 and moved the break sequence outside the loop.
1903 We must move the LOOP_END note to where the
1904 loop really ends now, or we will confuse loop
1905 optimization. Stop if we find a LOOP_BEG note
1906 first, since we don't want to move the LOOP_END
1907 note in that case. */
1908 for (;range2after != label2; range2after = rangenext)
1910 rangenext = NEXT_INSN (range2after);
1911 if (GET_CODE (range2after) == NOTE)
1913 if (NOTE_LINE_NUMBER (range2after)
1914 == NOTE_INSN_LOOP_END)
1916 NEXT_INSN (PREV_INSN (range2after))
1918 PREV_INSN (rangenext)
1919 = PREV_INSN (range2after);
1920 PREV_INSN (range2after)
1921 = PREV_INSN (range1beg);
1922 NEXT_INSN (range2after) = range1beg;
1923 NEXT_INSN (PREV_INSN (range1beg))
1925 PREV_INSN (range1beg) = range2after;
1927 else if (NOTE_LINE_NUMBER (range2after)
1928 == NOTE_INSN_LOOP_BEG)
1938 /* Now that the jump has been tensioned,
1939 try cross jumping: check for identical code
1940 before the jump and before its target label. */
1942 /* First, cross jumping of conditional jumps: */
1944 if (cross_jump && condjump_p (insn))
1946 rtx newjpos, newlpos;
1947 rtx x = prev_real_insn (JUMP_LABEL (insn));
1949 /* A conditional jump may be crossjumped
1950 only if the place it jumps to follows
1951 an opposing jump that comes back here. */
1953 if (x != 0 && ! jump_back_p (x, insn))
1954 /* We have no opposing jump;
1955 cannot cross jump this insn. */
1959 /* TARGET is nonzero if it is ok to cross jump
1960 to code before TARGET. If so, see if matches. */
1962 find_cross_jump (insn, x, 2,
1963 &newjpos, &newlpos);
1967 do_cross_jump (insn, newjpos, newlpos);
1968 /* Make the old conditional jump
1969 into an unconditional one. */
1970 SET_SRC (PATTERN (insn))
1971 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
1972 INSN_CODE (insn) = -1;
1973 emit_barrier_after (insn);
1974 /* Add to jump_chain unless this is a new label
1975 whose UID is too large. */
1976 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1978 jump_chain[INSN_UID (insn)]
1979 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1980 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1987 /* Cross jumping of unconditional jumps:
1988 a few differences. */
1990 if (cross_jump && simplejump_p (insn))
1992 rtx newjpos, newlpos;
1997 /* TARGET is nonzero if it is ok to cross jump
1998 to code before TARGET. If so, see if matches. */
1999 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2000 &newjpos, &newlpos);
2002 /* If cannot cross jump to code before the label,
2003 see if we can cross jump to another jump to
2005 /* Try each other jump to this label. */
2006 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2007 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2008 target != 0 && newjpos == 0;
2009 target = jump_chain[INSN_UID (target)])
2011 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2012 /* Ignore TARGET if it's deleted. */
2013 && ! INSN_DELETED_P (target))
2014 find_cross_jump (insn, target, 2,
2015 &newjpos, &newlpos);
2019 do_cross_jump (insn, newjpos, newlpos);
2025 /* This code was dead in the previous jump.c! */
2026 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2028 /* Return insns all "jump to the same place"
2029 so we can cross-jump between any two of them. */
2031 rtx newjpos, newlpos, target;
2035 /* If cannot cross jump to code before the label,
2036 see if we can cross jump to another jump to
2038 /* Try each other jump to this label. */
2039 for (target = jump_chain[0];
2040 target != 0 && newjpos == 0;
2041 target = jump_chain[INSN_UID (target)])
2043 && ! INSN_DELETED_P (target)
2044 && GET_CODE (PATTERN (target)) == RETURN)
2045 find_cross_jump (insn, target, 2,
2046 &newjpos, &newlpos);
2050 do_cross_jump (insn, newjpos, newlpos);
2061 /* Delete extraneous line number notes.
2062 Note that two consecutive notes for different lines are not really
2063 extraneous. There should be some indication where that line belonged,
2064 even if it became empty. */
2069 for (insn = f; insn; insn = NEXT_INSN (insn))
2070 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2072 /* Delete this note if it is identical to previous note. */
2074 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2075 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2088 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2089 in front of it. If the machine allows it at this point (we might be
2090 after reload for a leaf routine), it will improve optimization for it
2091 to be there. We do this both here and at the start of this pass since
2092 the RETURN might have been deleted by some of our optimizations. */
2093 insn = get_last_insn ();
2094 while (insn && GET_CODE (insn) == NOTE)
2095 insn = PREV_INSN (insn);
2097 if (insn && GET_CODE (insn) != BARRIER)
2099 emit_jump_insn (gen_return ());
2105 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2106 If so, delete it, and record that this function can drop off the end. */
2112 /* One label can follow the end-note: the return label. */
2113 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2114 /* Ordinary insns can follow it if returning a structure. */
2115 || GET_CODE (insn) == INSN
2116 /* If machine uses explicit RETURN insns, no epilogue,
2117 then one of them follows the note. */
2118 || (GET_CODE (insn) == JUMP_INSN
2119 && GET_CODE (PATTERN (insn)) == RETURN)
2120 /* A barrier can follow the return insn. */
2121 || GET_CODE (insn) == BARRIER
2122 /* Other kinds of notes can follow also. */
2123 || (GET_CODE (insn) == NOTE
2124 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2125 insn = PREV_INSN (insn);
2128 /* Report if control can fall through at the end of the function. */
2129 if (insn && GET_CODE (insn) == NOTE
2130 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2136 /* Show JUMP_CHAIN no longer valid. */
2140 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2141 jump. Assume that this unconditional jump is to the exit test code. If
2142 the code is sufficiently simple, make a copy of it before INSN,
2143 followed by a jump to the exit of the loop. Then delete the unconditional
2146 Return 1 if we made the change, else 0.
2148 This is only safe immediately after a regscan pass because it uses the
2149 values of regno_first_uid and regno_last_uid. */
2152 duplicate_loop_exit_test (loop_start)
2155 rtx insn, set, reg, p, link;
2158 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2160 int max_reg = max_reg_num ();
2163 /* Scan the exit code. We do not perform this optimization if any insn:
2167 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2168 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2169 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2172 Also, don't do this if the exit code is more than 20 insns. */
2174 for (insn = exitcode;
2176 && ! (GET_CODE (insn) == NOTE
2177 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2178 insn = NEXT_INSN (insn))
2180 switch (GET_CODE (insn))
2186 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2187 a jump immediately after the loop start that branches outside
2188 the loop but within an outer loop, near the exit test.
2189 If we copied this exit test and created a phony
2190 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2191 before the exit test look like these could be safely moved
2192 out of the loop even if they actually may be never executed.
2193 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2195 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2196 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2197 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2198 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2203 if (++num_insns > 20
2204 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2205 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2211 /* Unless INSN is zero, we can do the optimization. */
2217 /* See if any insn sets a register only used in the loop exit code and
2218 not a user variable. If so, replace it with a new register. */
2219 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2220 if (GET_CODE (insn) == INSN
2221 && (set = single_set (insn)) != 0
2222 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2223 || (GET_CODE (reg) == SUBREG
2224 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2225 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2226 && regno_first_uid[REGNO (reg)] == INSN_UID (insn))
2228 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2229 if (regno_last_uid[REGNO (reg)] == INSN_UID (p))
2234 /* We can do the replacement. Allocate reg_map if this is the
2235 first replacement we found. */
2238 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2239 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2242 REG_LOOP_TEST_P (reg) = 1;
2244 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2248 /* Now copy each insn. */
2249 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2250 switch (GET_CODE (insn))
2253 copy = emit_barrier_before (loop_start);
2256 /* Only copy line-number notes. */
2257 if (NOTE_LINE_NUMBER (insn) >= 0)
2259 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2260 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2265 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2267 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2269 mark_jump_label (PATTERN (copy), copy, 0);
2271 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2273 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2274 if (REG_NOTE_KIND (link) != REG_LABEL)
2276 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
2277 XEXP (link, 0), REG_NOTES (copy)));
2278 if (reg_map && REG_NOTES (copy))
2279 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2283 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2285 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2286 mark_jump_label (PATTERN (copy), copy, 0);
2287 if (REG_NOTES (insn))
2289 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2291 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2294 /* If this is a simple jump, add it to the jump chain. */
2296 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2297 && simplejump_p (copy))
2299 jump_chain[INSN_UID (copy)]
2300 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2301 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2309 /* Now clean up by emitting a jump to the end label and deleting the jump
2310 at the start of the loop. */
2311 if (! copy || GET_CODE (copy) != BARRIER)
2313 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2315 mark_jump_label (PATTERN (copy), copy, 0);
2316 if (INSN_UID (copy) < max_jump_chain
2317 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2319 jump_chain[INSN_UID (copy)]
2320 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2321 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2323 emit_barrier_before (loop_start);
2326 /* Mark the exit code as the virtual top of the converted loop. */
2327 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2329 delete_insn (next_nonnote_insn (loop_start));
2334 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2335 loop-end notes between START and END out before START. Assume that
2336 END is not such a note. START may be such a note. Returns the value
2337 of the new starting insn, which may be different if the original start
2341 squeeze_notes (start, end)
2347 for (insn = start; insn != end; insn = next)
2349 next = NEXT_INSN (insn);
2350 if (GET_CODE (insn) == NOTE
2351 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2352 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2353 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2354 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2355 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2356 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2362 rtx prev = PREV_INSN (insn);
2363 PREV_INSN (insn) = PREV_INSN (start);
2364 NEXT_INSN (insn) = start;
2365 NEXT_INSN (PREV_INSN (insn)) = insn;
2366 PREV_INSN (NEXT_INSN (insn)) = insn;
2367 NEXT_INSN (prev) = next;
2368 PREV_INSN (next) = prev;
2376 /* Compare the instructions before insn E1 with those before E2
2377 to find an opportunity for cross jumping.
2378 (This means detecting identical sequences of insns followed by
2379 jumps to the same place, or followed by a label and a jump
2380 to that label, and replacing one with a jump to the other.)
2382 Assume E1 is a jump that jumps to label E2
2383 (that is not always true but it might as well be).
2384 Find the longest possible equivalent sequences
2385 and store the first insns of those sequences into *F1 and *F2.
2386 Store zero there if no equivalent preceding instructions are found.
2388 We give up if we find a label in stream 1.
2389 Actually we could transfer that label into stream 2. */
2392 find_cross_jump (e1, e2, minimum, f1, f2)
2397 register rtx i1 = e1, i2 = e2;
2398 register rtx p1, p2;
2401 rtx last1 = 0, last2 = 0;
2402 rtx afterlast1 = 0, afterlast2 = 0;
2410 i1 = prev_nonnote_insn (i1);
2412 i2 = PREV_INSN (i2);
2413 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2414 i2 = PREV_INSN (i2);
2419 /* Don't allow the range of insns preceding E1 or E2
2420 to include the other (E2 or E1). */
2421 if (i2 == e1 || i1 == e2)
2424 /* If we will get to this code by jumping, those jumps will be
2425 tensioned to go directly to the new label (before I2),
2426 so this cross-jumping won't cost extra. So reduce the minimum. */
2427 if (GET_CODE (i1) == CODE_LABEL)
2433 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2439 /* If this is a CALL_INSN, compare register usage information.
2440 If we don't check this on stack register machines, the two
2441 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2442 numbers of stack registers in the same basic block.
2443 If we don't check this on machines with delay slots, a delay slot may
2444 be filled that clobbers a parameter expected by the subroutine.
2446 ??? We take the simple route for now and assume that if they're
2447 equal, they were constructed identically. */
2449 if (GET_CODE (i1) == CALL_INSN
2450 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2451 CALL_INSN_FUNCTION_USAGE (i2)))
2455 /* If cross_jump_death_matters is not 0, the insn's mode
2456 indicates whether or not the insn contains any stack-like
2459 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2461 /* If register stack conversion has already been done, then
2462 death notes must also be compared before it is certain that
2463 the two instruction streams match. */
2466 HARD_REG_SET i1_regset, i2_regset;
2468 CLEAR_HARD_REG_SET (i1_regset);
2469 CLEAR_HARD_REG_SET (i2_regset);
2471 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2472 if (REG_NOTE_KIND (note) == REG_DEAD
2473 && STACK_REG_P (XEXP (note, 0)))
2474 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2476 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2477 if (REG_NOTE_KIND (note) == REG_DEAD
2478 && STACK_REG_P (XEXP (note, 0)))
2479 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2481 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2490 if (lose || GET_CODE (p1) != GET_CODE (p2)
2491 || ! rtx_renumbered_equal_p (p1, p2))
2493 /* The following code helps take care of G++ cleanups. */
2497 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2498 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2499 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2500 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2501 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2502 /* If the equivalences are not to a constant, they may
2503 reference pseudos that no longer exist, so we can't
2505 && CONSTANT_P (XEXP (equiv1, 0))
2506 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2508 rtx s1 = single_set (i1);
2509 rtx s2 = single_set (i2);
2510 if (s1 != 0 && s2 != 0
2511 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2513 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2514 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2515 if (! rtx_renumbered_equal_p (p1, p2))
2517 else if (apply_change_group ())
2522 /* Insns fail to match; cross jumping is limited to the following
2526 /* Don't allow the insn after a compare to be shared by
2527 cross-jumping unless the compare is also shared.
2528 Here, if either of these non-matching insns is a compare,
2529 exclude the following insn from possible cross-jumping. */
2530 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2531 last1 = afterlast1, last2 = afterlast2, ++minimum;
2534 /* If cross-jumping here will feed a jump-around-jump
2535 optimization, this jump won't cost extra, so reduce
2537 if (GET_CODE (i1) == JUMP_INSN
2539 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2545 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2547 /* Ok, this insn is potentially includable in a cross-jump here. */
2548 afterlast1 = last1, afterlast2 = last2;
2549 last1 = i1, last2 = i2, --minimum;
2553 if (minimum <= 0 && last1 != 0 && last1 != e1)
2554 *f1 = last1, *f2 = last2;
2558 do_cross_jump (insn, newjpos, newlpos)
2559 rtx insn, newjpos, newlpos;
2561 /* Find an existing label at this point
2562 or make a new one if there is none. */
2563 register rtx label = get_label_before (newlpos);
2565 /* Make the same jump insn jump to the new point. */
2566 if (GET_CODE (PATTERN (insn)) == RETURN)
2568 /* Remove from jump chain of returns. */
2569 delete_from_jump_chain (insn);
2570 /* Change the insn. */
2571 PATTERN (insn) = gen_jump (label);
2572 INSN_CODE (insn) = -1;
2573 JUMP_LABEL (insn) = label;
2574 LABEL_NUSES (label)++;
2575 /* Add to new the jump chain. */
2576 if (INSN_UID (label) < max_jump_chain
2577 && INSN_UID (insn) < max_jump_chain)
2579 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2580 jump_chain[INSN_UID (label)] = insn;
2584 redirect_jump (insn, label);
2586 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2587 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2588 the NEWJPOS stream. */
2590 while (newjpos != insn)
2594 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2595 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2596 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2597 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2598 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2599 remove_note (newlpos, lnote);
2601 delete_insn (newjpos);
2602 newjpos = next_real_insn (newjpos);
2603 newlpos = next_real_insn (newlpos);
2607 /* Return the label before INSN, or put a new label there. */
2610 get_label_before (insn)
2615 /* Find an existing label at this point
2616 or make a new one if there is none. */
2617 label = prev_nonnote_insn (insn);
2619 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2621 rtx prev = PREV_INSN (insn);
2623 label = gen_label_rtx ();
2624 emit_label_after (label, prev);
2625 LABEL_NUSES (label) = 0;
2630 /* Return the label after INSN, or put a new label there. */
2633 get_label_after (insn)
2638 /* Find an existing label at this point
2639 or make a new one if there is none. */
2640 label = next_nonnote_insn (insn);
2642 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2644 label = gen_label_rtx ();
2645 emit_label_after (label, insn);
2646 LABEL_NUSES (label) = 0;
2651 /* Return 1 if INSN is a jump that jumps to right after TARGET
2652 only on the condition that TARGET itself would drop through.
2653 Assumes that TARGET is a conditional jump. */
2656 jump_back_p (insn, target)
2660 enum rtx_code codei, codet;
2662 if (simplejump_p (insn) || ! condjump_p (insn)
2663 || simplejump_p (target)
2664 || target != prev_real_insn (JUMP_LABEL (insn)))
2667 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2668 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2670 codei = GET_CODE (cinsn);
2671 codet = GET_CODE (ctarget);
2673 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2675 if (! can_reverse_comparison_p (cinsn, insn))
2677 codei = reverse_condition (codei);
2680 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2682 if (! can_reverse_comparison_p (ctarget, target))
2684 codet = reverse_condition (codet);
2687 return (codei == codet
2688 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2689 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2692 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2693 return non-zero if it is safe to reverse this comparison. It is if our
2694 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2695 this is known to be an integer comparison. */
2698 can_reverse_comparison_p (comparison, insn)
2704 /* If this is not actually a comparison, we can't reverse it. */
2705 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2708 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2709 /* If this is an NE comparison, it is safe to reverse it to an EQ
2710 comparison and vice versa, even for floating point. If no operands
2711 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2712 always false and NE is always true, so the reversal is also valid. */
2714 || GET_CODE (comparison) == NE
2715 || GET_CODE (comparison) == EQ)
2718 arg0 = XEXP (comparison, 0);
2720 /* Make sure ARG0 is one of the actual objects being compared. If we
2721 can't do this, we can't be sure the comparison can be reversed.
2723 Handle cc0 and a MODE_CC register. */
2724 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2730 rtx prev = prev_nonnote_insn (insn);
2731 rtx set = single_set (prev);
2733 if (set == 0 || SET_DEST (set) != arg0)
2736 arg0 = SET_SRC (set);
2738 if (GET_CODE (arg0) == COMPARE)
2739 arg0 = XEXP (arg0, 0);
2742 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2743 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2744 return (GET_CODE (arg0) == CONST_INT
2745 || (GET_MODE (arg0) != VOIDmode
2746 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2747 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2750 /* Given an rtx-code for a comparison, return the code
2751 for the negated comparison.
2752 WATCH OUT! reverse_condition is not safe to use on a jump
2753 that might be acting on the results of an IEEE floating point comparison,
2754 because of the special treatment of non-signaling nans in comparisons.
2755 Use can_reverse_comparison_p to be sure. */
2758 reverse_condition (code)
2799 /* Similar, but return the code when two operands of a comparison are swapped.
2800 This IS safe for IEEE floating-point. */
2803 swap_condition (code)
2842 /* Given a comparison CODE, return the corresponding unsigned comparison.
2843 If CODE is an equality comparison or already an unsigned comparison,
2844 CODE is returned. */
2847 unsigned_condition (code)
2877 /* Similarly, return the signed version of a comparison. */
2880 signed_condition (code)
2910 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2911 truth of CODE1 implies the truth of CODE2. */
2914 comparison_dominates_p (code1, code2)
2915 enum rtx_code code1, code2;
2923 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
2928 if (code2 == LE || code2 == NE)
2933 if (code2 == GE || code2 == NE)
2938 if (code2 == LEU || code2 == NE)
2943 if (code2 == GEU || code2 == NE)
2951 /* Return 1 if INSN is an unconditional jump and nothing else. */
2957 return (GET_CODE (insn) == JUMP_INSN
2958 && GET_CODE (PATTERN (insn)) == SET
2959 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2960 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2963 /* Return nonzero if INSN is a (possibly) conditional jump
2964 and nothing more. */
2970 register rtx x = PATTERN (insn);
2971 if (GET_CODE (x) != SET)
2973 if (GET_CODE (SET_DEST (x)) != PC)
2975 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2977 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2979 if (XEXP (SET_SRC (x), 2) == pc_rtx
2980 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2981 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2983 if (XEXP (SET_SRC (x), 1) == pc_rtx
2984 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2985 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2990 /* Return nonzero if INSN is a (possibly) conditional jump
2991 and nothing more. */
2994 condjump_in_parallel_p (insn)
2997 register rtx x = PATTERN (insn);
2999 if (GET_CODE (x) != PARALLEL)
3002 x = XVECEXP (x, 0, 0);
3004 if (GET_CODE (x) != SET)
3006 if (GET_CODE (SET_DEST (x)) != PC)
3008 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3010 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3012 if (XEXP (SET_SRC (x), 2) == pc_rtx
3013 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3014 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3016 if (XEXP (SET_SRC (x), 1) == pc_rtx
3017 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3018 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3023 /* Return 1 if X is an RTX that does nothing but set the condition codes
3024 and CLOBBER or USE registers.
3025 Return -1 if X does explicitly set the condition codes,
3026 but also does other things. */
3033 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3035 if (GET_CODE (x) == PARALLEL)
3039 int other_things = 0;
3040 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3042 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3043 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3045 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3048 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3056 /* Follow any unconditional jump at LABEL;
3057 return the ultimate label reached by any such chain of jumps.
3058 If LABEL is not followed by a jump, return LABEL.
3059 If the chain loops or we can't find end, return LABEL,
3060 since that tells caller to avoid changing the insn.
3062 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3063 a USE or CLOBBER. */
3066 follow_jumps (label)
3071 register rtx value = label;
3076 && (insn = next_active_insn (value)) != 0
3077 && GET_CODE (insn) == JUMP_INSN
3078 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3079 || GET_CODE (PATTERN (insn)) == RETURN)
3080 && (next = NEXT_INSN (insn))
3081 && GET_CODE (next) == BARRIER);
3084 /* Don't chain through the insn that jumps into a loop
3085 from outside the loop,
3086 since that would create multiple loop entry jumps
3087 and prevent loop optimization. */
3089 if (!reload_completed)
3090 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3091 if (GET_CODE (tem) == NOTE
3092 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
3095 /* If we have found a cycle, make the insn jump to itself. */
3096 if (JUMP_LABEL (insn) == label)
3099 tem = next_active_insn (JUMP_LABEL (insn));
3100 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3101 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3104 value = JUMP_LABEL (insn);
3111 /* Assuming that field IDX of X is a vector of label_refs,
3112 replace each of them by the ultimate label reached by it.
3113 Return nonzero if a change is made.
3114 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3117 tension_vector_labels (x, idx)
3123 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3125 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3126 register rtx nlabel = follow_jumps (olabel);
3127 if (nlabel && nlabel != olabel)
3129 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3130 ++LABEL_NUSES (nlabel);
3131 if (--LABEL_NUSES (olabel) == 0)
3132 delete_insn (olabel);
3139 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3140 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3141 in INSN, then store one of them in JUMP_LABEL (INSN).
3142 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3143 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3144 Also, when there are consecutive labels, canonicalize on the last of them.
3146 Note that two labels separated by a loop-beginning note
3147 must be kept distinct if we have not yet done loop-optimization,
3148 because the gap between them is where loop-optimize
3149 will want to move invariant code to. CROSS_JUMP tells us
3150 that loop-optimization is done with.
3152 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3153 two labels distinct if they are separated by only USE or CLOBBER insns. */
3156 mark_jump_label (x, insn, cross_jump)
3161 register RTX_CODE code = GET_CODE (x);
3179 /* If this is a constant-pool reference, see if it is a label. */
3180 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3181 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3182 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3187 rtx label = XEXP (x, 0);
3192 if (GET_CODE (label) != CODE_LABEL)
3195 /* Ignore references to labels of containing functions. */
3196 if (LABEL_REF_NONLOCAL_P (x))
3199 /* If there are other labels following this one,
3200 replace it with the last of the consecutive labels. */
3201 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3203 if (GET_CODE (next) == CODE_LABEL)
3205 else if (cross_jump && GET_CODE (next) == INSN
3206 && (GET_CODE (PATTERN (next)) == USE
3207 || GET_CODE (PATTERN (next)) == CLOBBER))
3209 else if (GET_CODE (next) != NOTE)
3211 else if (! cross_jump
3212 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3213 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
3217 XEXP (x, 0) = label;
3218 ++LABEL_NUSES (label);
3222 if (GET_CODE (insn) == JUMP_INSN)
3223 JUMP_LABEL (insn) = label;
3225 /* If we've changed OLABEL and we had a REG_LABEL note
3226 for it, update it as well. */
3227 else if (label != olabel
3228 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3229 XEXP (note, 0) = label;
3231 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3233 else if (! find_reg_note (insn, REG_LABEL, label))
3235 rtx next = next_real_insn (label);
3236 /* Don't record labels that refer to dispatch tables.
3237 This is not necessary, since the tablejump
3238 references the same label.
3239 And if we did record them, flow.c would make worse code. */
3241 || ! (GET_CODE (next) == JUMP_INSN
3242 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3243 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
3244 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
3251 /* Do walk the labels in a vector, but not the first operand of an
3252 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3256 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3258 for (i = 0; i < XVECLEN (x, eltnum); i++)
3259 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3264 fmt = GET_RTX_FORMAT (code);
3265 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3268 mark_jump_label (XEXP (x, i), insn, cross_jump);
3269 else if (fmt[i] == 'E')
3272 for (j = 0; j < XVECLEN (x, i); j++)
3273 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3278 /* If all INSN does is set the pc, delete it,
3279 and delete the insn that set the condition codes for it
3280 if that's what the previous thing was. */
3286 register rtx set = single_set (insn);
3288 if (set && GET_CODE (SET_DEST (set)) == PC)
3289 delete_computation (insn);
3292 /* Delete INSN and recursively delete insns that compute values used only
3293 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3294 If we are running before flow.c, we need do nothing since flow.c will
3295 delete dead code. We also can't know if the registers being used are
3296 dead or not at this point.
3298 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3299 nothing other than set a register that dies in this insn, we can delete
3302 On machines with CC0, if CC0 is used in this insn, we may be able to
3303 delete the insn that set it. */
3306 delete_computation (insn)
3312 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3314 rtx prev = prev_nonnote_insn (insn);
3315 /* We assume that at this stage
3316 CC's are always set explicitly
3317 and always immediately before the jump that
3318 will use them. So if the previous insn
3319 exists to set the CC's, delete it
3320 (unless it performs auto-increments, etc.). */
3321 if (prev && GET_CODE (prev) == INSN
3322 && sets_cc0_p (PATTERN (prev)))
3324 if (sets_cc0_p (PATTERN (prev)) > 0
3325 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3326 delete_computation (prev);
3328 /* Otherwise, show that cc0 won't be used. */
3329 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
3330 cc0_rtx, REG_NOTES (prev));
3335 for (note = REG_NOTES (insn); note; note = next)
3339 next = XEXP (note, 1);
3341 if (REG_NOTE_KIND (note) != REG_DEAD
3342 /* Verify that the REG_NOTE is legitimate. */
3343 || GET_CODE (XEXP (note, 0)) != REG)
3346 for (our_prev = prev_nonnote_insn (insn);
3347 our_prev && GET_CODE (our_prev) == INSN;
3348 our_prev = prev_nonnote_insn (our_prev))
3350 /* If we reach a SEQUENCE, it is too complex to try to
3351 do anything with it, so give up. */
3352 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3355 if (GET_CODE (PATTERN (our_prev)) == USE
3356 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3357 /* reorg creates USEs that look like this. We leave them
3358 alone because reorg needs them for its own purposes. */
3361 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3363 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3366 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3368 /* If we find a SET of something else, we can't
3373 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3375 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3377 if (GET_CODE (part) == SET
3378 && SET_DEST (part) != XEXP (note, 0))
3382 if (i == XVECLEN (PATTERN (our_prev), 0))
3383 delete_computation (our_prev);
3385 else if (GET_CODE (PATTERN (our_prev)) == SET
3386 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3387 delete_computation (our_prev);
3392 /* If OUR_PREV references the register that dies here, it is an
3393 additional use. Hence any prior SET isn't dead. However, this
3394 insn becomes the new place for the REG_DEAD note. */
3395 if (reg_overlap_mentioned_p (XEXP (note, 0),
3396 PATTERN (our_prev)))
3398 XEXP (note, 1) = REG_NOTES (our_prev);
3399 REG_NOTES (our_prev) = note;
3408 /* Delete insn INSN from the chain of insns and update label ref counts.
3409 May delete some following insns as a consequence; may even delete
3410 a label elsewhere and insns that follow it.
3412 Returns the first insn after INSN that was not deleted. */
3418 register rtx next = NEXT_INSN (insn);
3419 register rtx prev = PREV_INSN (insn);
3420 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3421 register int dont_really_delete = 0;
3423 while (next && INSN_DELETED_P (next))
3424 next = NEXT_INSN (next);
3426 /* This insn is already deleted => return first following nondeleted. */
3427 if (INSN_DELETED_P (insn))
3430 /* Don't delete user-declared labels. Convert them to special NOTEs
3432 if (was_code_label && LABEL_NAME (insn) != 0
3433 && optimize && ! dont_really_delete)
3435 PUT_CODE (insn, NOTE);
3436 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3437 NOTE_SOURCE_FILE (insn) = 0;
3438 dont_really_delete = 1;
3441 /* Mark this insn as deleted. */
3442 INSN_DELETED_P (insn) = 1;
3444 /* If this is an unconditional jump, delete it from the jump chain. */
3445 if (simplejump_p (insn))
3446 delete_from_jump_chain (insn);
3448 /* If instruction is followed by a barrier,
3449 delete the barrier too. */
3451 if (next != 0 && GET_CODE (next) == BARRIER)
3453 INSN_DELETED_P (next) = 1;
3454 next = NEXT_INSN (next);
3457 /* Patch out INSN (and the barrier if any) */
3459 if (optimize && ! dont_really_delete)
3463 NEXT_INSN (prev) = next;
3464 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3465 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3466 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3471 PREV_INSN (next) = prev;
3472 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3473 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3476 if (prev && NEXT_INSN (prev) == 0)
3477 set_last_insn (prev);
3480 /* If deleting a jump, decrement the count of the label,
3481 and delete the label if it is now unused. */
3483 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3484 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3486 /* This can delete NEXT or PREV,
3487 either directly if NEXT is JUMP_LABEL (INSN),
3488 or indirectly through more levels of jumps. */
3489 delete_insn (JUMP_LABEL (insn));
3490 /* I feel a little doubtful about this loop,
3491 but I see no clean and sure alternative way
3492 to find the first insn after INSN that is not now deleted.
3493 I hope this works. */
3494 while (next && INSN_DELETED_P (next))
3495 next = NEXT_INSN (next);
3499 /* Likewise if we're deleting a dispatch table. */
3501 if (GET_CODE (insn) == JUMP_INSN
3502 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3503 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3505 rtx pat = PATTERN (insn);
3506 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3507 int len = XVECLEN (pat, diff_vec_p);
3509 for (i = 0; i < len; i++)
3510 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3511 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3512 while (next && INSN_DELETED_P (next))
3513 next = NEXT_INSN (next);
3517 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3518 prev = PREV_INSN (prev);
3520 /* If INSN was a label and a dispatch table follows it,
3521 delete the dispatch table. The tablejump must have gone already.
3522 It isn't useful to fall through into a table. */
3525 && NEXT_INSN (insn) != 0
3526 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3527 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3528 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3529 next = delete_insn (NEXT_INSN (insn));
3531 /* If INSN was a label, delete insns following it if now unreachable. */
3533 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3535 register RTX_CODE code;
3537 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3538 || code == NOTE || code == BARRIER
3539 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3542 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3543 next = NEXT_INSN (next);
3544 /* Keep going past other deleted labels to delete what follows. */
3545 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3546 next = NEXT_INSN (next);
3548 /* Note: if this deletes a jump, it can cause more
3549 deletion of unreachable code, after a different label.
3550 As long as the value from this recursive call is correct,
3551 this invocation functions correctly. */
3552 next = delete_insn (next);
3559 /* Advance from INSN till reaching something not deleted
3560 then return that. May return INSN itself. */
3563 next_nondeleted_insn (insn)
3566 while (INSN_DELETED_P (insn))
3567 insn = NEXT_INSN (insn);
3571 /* Delete a range of insns from FROM to TO, inclusive.
3572 This is for the sake of peephole optimization, so assume
3573 that whatever these insns do will still be done by a new
3574 peephole insn that will replace them. */
3577 delete_for_peephole (from, to)
3578 register rtx from, to;
3580 register rtx insn = from;
3584 register rtx next = NEXT_INSN (insn);
3585 register rtx prev = PREV_INSN (insn);
3587 if (GET_CODE (insn) != NOTE)
3589 INSN_DELETED_P (insn) = 1;
3591 /* Patch this insn out of the chain. */
3592 /* We don't do this all at once, because we
3593 must preserve all NOTEs. */
3595 NEXT_INSN (prev) = next;
3598 PREV_INSN (next) = prev;
3606 /* Note that if TO is an unconditional jump
3607 we *do not* delete the BARRIER that follows,
3608 since the peephole that replaces this sequence
3609 is also an unconditional jump in that case. */
3612 /* Invert the condition of the jump JUMP, and make it jump
3613 to label NLABEL instead of where it jumps now. */
3616 invert_jump (jump, nlabel)
3619 /* We have to either invert the condition and change the label or
3620 do neither. Either operation could fail. We first try to invert
3621 the jump. If that succeeds, we try changing the label. If that fails,
3622 we invert the jump back to what it was. */
3624 if (! invert_exp (PATTERN (jump), jump))
3627 if (redirect_jump (jump, nlabel))
3630 if (! invert_exp (PATTERN (jump), jump))
3631 /* This should just be putting it back the way it was. */
3637 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3639 Return 1 if we can do so, 0 if we cannot find a way to do so that
3640 matches a pattern. */
3643 invert_exp (x, insn)
3647 register RTX_CODE code;
3651 code = GET_CODE (x);
3653 if (code == IF_THEN_ELSE)
3655 register rtx comp = XEXP (x, 0);
3658 /* We can do this in two ways: The preferable way, which can only
3659 be done if this is not an integer comparison, is to reverse
3660 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3661 of the IF_THEN_ELSE. If we can't do either, fail. */
3663 if (can_reverse_comparison_p (comp, insn)
3664 && validate_change (insn, &XEXP (x, 0),
3665 gen_rtx (reverse_condition (GET_CODE (comp)),
3666 GET_MODE (comp), XEXP (comp, 0),
3667 XEXP (comp, 1)), 0))
3671 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3672 validate_change (insn, &XEXP (x, 2), tem, 1);
3673 return apply_change_group ();
3676 fmt = GET_RTX_FORMAT (code);
3677 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3680 if (! invert_exp (XEXP (x, i), insn))
3685 for (j = 0; j < XVECLEN (x, i); j++)
3686 if (!invert_exp (XVECEXP (x, i, j), insn))
3694 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3695 If the old jump target label is unused as a result,
3696 it and the code following it may be deleted.
3698 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3701 The return value will be 1 if the change was made, 0 if it wasn't (this
3702 can only occur for NLABEL == 0). */
3705 redirect_jump (jump, nlabel)
3708 register rtx olabel = JUMP_LABEL (jump);
3710 if (nlabel == olabel)
3713 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3716 /* If this is an unconditional branch, delete it from the jump_chain of
3717 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3718 have UID's in range and JUMP_CHAIN is valid). */
3719 if (jump_chain && (simplejump_p (jump)
3720 || GET_CODE (PATTERN (jump)) == RETURN))
3722 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3724 delete_from_jump_chain (jump);
3725 if (label_index < max_jump_chain
3726 && INSN_UID (jump) < max_jump_chain)
3728 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3729 jump_chain[label_index] = jump;
3733 JUMP_LABEL (jump) = nlabel;
3735 ++LABEL_NUSES (nlabel);
3737 if (olabel && --LABEL_NUSES (olabel) == 0)
3738 delete_insn (olabel);
3743 /* Delete the instruction JUMP from any jump chain it might be on. */
3746 delete_from_jump_chain (jump)
3750 rtx olabel = JUMP_LABEL (jump);
3752 /* Handle unconditional jumps. */
3753 if (jump_chain && olabel != 0
3754 && INSN_UID (olabel) < max_jump_chain
3755 && simplejump_p (jump))
3756 index = INSN_UID (olabel);
3757 /* Handle return insns. */
3758 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3762 if (jump_chain[index] == jump)
3763 jump_chain[index] = jump_chain[INSN_UID (jump)];
3768 for (insn = jump_chain[index];
3770 insn = jump_chain[INSN_UID (insn)])
3771 if (jump_chain[INSN_UID (insn)] == jump)
3773 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3779 /* If NLABEL is nonzero, throughout the rtx at LOC,
3780 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3781 zero, alter (RETURN) to (LABEL_REF NLABEL).
3783 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3784 validity with validate_change. Convert (set (pc) (label_ref olabel))
3787 Return 0 if we found a change we would like to make but it is invalid.
3788 Otherwise, return 1. */
3791 redirect_exp (loc, olabel, nlabel, insn)
3796 register rtx x = *loc;
3797 register RTX_CODE code = GET_CODE (x);
3801 if (code == LABEL_REF)
3803 if (XEXP (x, 0) == olabel)
3806 XEXP (x, 0) = nlabel;
3808 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3812 else if (code == RETURN && olabel == 0)
3814 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3815 if (loc == &PATTERN (insn))
3816 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3817 return validate_change (insn, loc, x, 0);
3820 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3821 && GET_CODE (SET_SRC (x)) == LABEL_REF
3822 && XEXP (SET_SRC (x), 0) == olabel)
3823 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3825 fmt = GET_RTX_FORMAT (code);
3826 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3829 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3834 for (j = 0; j < XVECLEN (x, i); j++)
3835 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3843 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3845 If the old jump target label (before the dispatch table) becomes unused,
3846 it and the dispatch table may be deleted. In that case, find the insn
3847 before the jump references that label and delete it and logical successors
3851 redirect_tablejump (jump, nlabel)
3854 register rtx olabel = JUMP_LABEL (jump);
3856 /* Add this jump to the jump_chain of NLABEL. */
3857 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3858 && INSN_UID (jump) < max_jump_chain)
3860 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3861 jump_chain[INSN_UID (nlabel)] = jump;
3864 PATTERN (jump) = gen_jump (nlabel);
3865 JUMP_LABEL (jump) = nlabel;
3866 ++LABEL_NUSES (nlabel);
3867 INSN_CODE (jump) = -1;
3869 if (--LABEL_NUSES (olabel) == 0)
3871 delete_labelref_insn (jump, olabel, 0);
3872 delete_insn (olabel);
3876 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3877 If we found one, delete it and then delete this insn if DELETE_THIS is
3878 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3881 delete_labelref_insn (insn, label, delete_this)
3888 if (GET_CODE (insn) != NOTE
3889 && reg_mentioned_p (label, PATTERN (insn)))
3900 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3901 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3915 /* Like rtx_equal_p except that it considers two REGs as equal
3916 if they renumber to the same value and considers two commutative
3917 operations to be the same if the order of the operands has been
3921 rtx_renumbered_equal_p (x, y)
3925 register RTX_CODE code = GET_CODE (x);
3931 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3932 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3933 && GET_CODE (SUBREG_REG (y)) == REG)))
3935 int reg_x = -1, reg_y = -1;
3936 int word_x = 0, word_y = 0;
3938 if (GET_MODE (x) != GET_MODE (y))
3941 /* If we haven't done any renumbering, don't
3942 make any assumptions. */
3943 if (reg_renumber == 0)
3944 return rtx_equal_p (x, y);
3948 reg_x = REGNO (SUBREG_REG (x));
3949 word_x = SUBREG_WORD (x);
3951 if (reg_renumber[reg_x] >= 0)
3953 reg_x = reg_renumber[reg_x] + word_x;
3961 if (reg_renumber[reg_x] >= 0)
3962 reg_x = reg_renumber[reg_x];
3965 if (GET_CODE (y) == SUBREG)
3967 reg_y = REGNO (SUBREG_REG (y));
3968 word_y = SUBREG_WORD (y);
3970 if (reg_renumber[reg_y] >= 0)
3972 reg_y = reg_renumber[reg_y];
3980 if (reg_renumber[reg_y] >= 0)
3981 reg_y = reg_renumber[reg_y];
3984 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3987 /* Now we have disposed of all the cases
3988 in which different rtx codes can match. */
3989 if (code != GET_CODE (y))
4001 return INTVAL (x) == INTVAL (y);
4004 /* We can't assume nonlocal labels have their following insns yet. */
4005 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4006 return XEXP (x, 0) == XEXP (y, 0);
4008 /* Two label-refs are equivalent if they point at labels
4009 in the same position in the instruction stream. */
4010 return (next_real_insn (XEXP (x, 0))
4011 == next_real_insn (XEXP (y, 0)));
4014 return XSTR (x, 0) == XSTR (y, 0);
4017 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4019 if (GET_MODE (x) != GET_MODE (y))
4022 /* For commutative operations, the RTX match if the operand match in any
4023 order. Also handle the simple binary and unary cases without a loop. */
4024 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4025 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4026 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4027 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4028 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4029 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4030 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4031 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4032 else if (GET_RTX_CLASS (code) == '1')
4033 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4035 /* Compare the elements. If any pair of corresponding elements
4036 fail to match, return 0 for the whole things. */
4038 fmt = GET_RTX_FORMAT (code);
4039 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4045 if (XWINT (x, i) != XWINT (y, i))
4050 if (XINT (x, i) != XINT (y, i))
4055 if (strcmp (XSTR (x, i), XSTR (y, i)))
4060 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4065 if (XEXP (x, i) != XEXP (y, i))
4072 if (XVECLEN (x, i) != XVECLEN (y, i))
4074 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4075 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4086 /* If X is a hard register or equivalent to one or a subregister of one,
4087 return the hard register number. If X is a pseudo register that was not
4088 assigned a hard register, return the pseudo register number. Otherwise,
4089 return -1. Any rtx is valid for X. */
4095 if (GET_CODE (x) == REG)
4097 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4098 return reg_renumber[REGNO (x)];
4101 if (GET_CODE (x) == SUBREG)
4103 int base = true_regnum (SUBREG_REG (x));
4104 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4105 return SUBREG_WORD (x) + base;
4110 /* Optimize code of the form:
4112 for (x = a[i]; x; ...)
4114 for (x = a[i]; x; ...)
4118 Loop optimize will change the above code into
4122 { ...; if (! (x = ...)) break; }
4125 { ...; if (! (x = ...)) break; }
4128 In general, if the first test fails, the program can branch
4129 directly to `foo' and skip the second try which is doomed to fail.
4130 We run this after loop optimization and before flow analysis. */
4132 /* When comparing the insn patterns, we track the fact that different
4133 pseudo-register numbers may have been used in each computation.
4134 The following array stores an equivalence -- same_regs[I] == J means
4135 that pseudo register I was used in the first set of tests in a context
4136 where J was used in the second set. We also count the number of such
4137 pending equivalences. If nonzero, the expressions really aren't the
4140 static int *same_regs;
4142 static int num_same_regs;
4144 /* Track any registers modified between the target of the first jump and
4145 the second jump. They never compare equal. */
4147 static char *modified_regs;
4149 /* Record if memory was modified. */
4151 static int modified_mem;
4153 /* Called via note_stores on each insn between the target of the first
4154 branch and the second branch. It marks any changed registers. */
4157 mark_modified_reg (dest, x)
4163 if (GET_CODE (dest) == SUBREG)
4164 dest = SUBREG_REG (dest);
4166 if (GET_CODE (dest) == MEM)
4169 if (GET_CODE (dest) != REG)
4172 regno = REGNO (dest);
4173 if (regno >= FIRST_PSEUDO_REGISTER)
4174 modified_regs[regno] = 1;
4176 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4177 modified_regs[regno + i] = 1;
4180 /* F is the first insn in the chain of insns. */
4183 thread_jumps (f, max_reg, flag_before_loop)
4186 int flag_before_loop;
4188 /* Basic algorithm is to find a conditional branch,
4189 the label it may branch to, and the branch after
4190 that label. If the two branches test the same condition,
4191 walk back from both branch paths until the insn patterns
4192 differ, or code labels are hit. If we make it back to
4193 the target of the first branch, then we know that the first branch
4194 will either always succeed or always fail depending on the relative
4195 senses of the two branches. So adjust the first branch accordingly
4198 rtx label, b1, b2, t1, t2;
4199 enum rtx_code code1, code2;
4200 rtx b1op0, b1op1, b2op0, b2op1;
4205 /* Allocate register tables and quick-reset table. */
4206 modified_regs = (char *) alloca (max_reg * sizeof (char));
4207 same_regs = (int *) alloca (max_reg * sizeof (int));
4208 all_reset = (int *) alloca (max_reg * sizeof (int));
4209 for (i = 0; i < max_reg; i++)
4216 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4218 /* Get to a candidate branch insn. */
4219 if (GET_CODE (b1) != JUMP_INSN
4220 || ! condjump_p (b1) || simplejump_p (b1)
4221 || JUMP_LABEL (b1) == 0)
4224 bzero (modified_regs, max_reg * sizeof (char));
4227 bcopy ((char *) all_reset, (char *) same_regs,
4228 max_reg * sizeof (int));
4231 label = JUMP_LABEL (b1);
4233 /* Look for a branch after the target. Record any registers and
4234 memory modified between the target and the branch. Stop when we
4235 get to a label since we can't know what was changed there. */
4236 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4238 if (GET_CODE (b2) == CODE_LABEL)
4241 else if (GET_CODE (b2) == JUMP_INSN)
4243 /* If this is an unconditional jump and is the only use of
4244 its target label, we can follow it. */
4245 if (simplejump_p (b2)
4246 && JUMP_LABEL (b2) != 0
4247 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4249 b2 = JUMP_LABEL (b2);
4256 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4259 if (GET_CODE (b2) == CALL_INSN)
4262 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4263 if (call_used_regs[i] && ! fixed_regs[i]
4264 && i != STACK_POINTER_REGNUM
4265 && i != FRAME_POINTER_REGNUM
4266 && i != HARD_FRAME_POINTER_REGNUM
4267 && i != ARG_POINTER_REGNUM)
4268 modified_regs[i] = 1;
4271 note_stores (PATTERN (b2), mark_modified_reg);
4274 /* Check the next candidate branch insn from the label
4277 || GET_CODE (b2) != JUMP_INSN
4279 || ! condjump_p (b2)
4280 || simplejump_p (b2))
4283 /* Get the comparison codes and operands, reversing the
4284 codes if appropriate. If we don't have comparison codes,
4285 we can't do anything. */
4286 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4287 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4288 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4289 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4290 code1 = reverse_condition (code1);
4292 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4293 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4294 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4295 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4296 code2 = reverse_condition (code2);
4298 /* If they test the same things and knowing that B1 branches
4299 tells us whether or not B2 branches, check if we
4300 can thread the branch. */
4301 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4302 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4303 && (comparison_dominates_p (code1, code2)
4304 || comparison_dominates_p (code1, reverse_condition (code2))))
4306 t1 = prev_nonnote_insn (b1);
4307 t2 = prev_nonnote_insn (b2);
4309 while (t1 != 0 && t2 != 0)
4313 /* We have reached the target of the first branch.
4314 If there are no pending register equivalents,
4315 we know that this branch will either always
4316 succeed (if the senses of the two branches are
4317 the same) or always fail (if not). */
4320 if (num_same_regs != 0)
4323 if (comparison_dominates_p (code1, code2))
4324 new_label = JUMP_LABEL (b2);
4326 new_label = get_label_after (b2);
4328 if (JUMP_LABEL (b1) != new_label)
4330 rtx prev = PREV_INSN (new_label);
4332 if (flag_before_loop
4333 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4335 /* Don't thread to the loop label. If a loop
4336 label is reused, loop optimization will
4337 be disabled for that loop. */
4338 new_label = gen_label_rtx ();
4339 emit_label_after (new_label, PREV_INSN (prev));
4341 changed |= redirect_jump (b1, new_label);
4346 /* If either of these is not a normal insn (it might be
4347 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4348 have already been skipped above.) Similarly, fail
4349 if the insns are different. */
4350 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4351 || recog_memoized (t1) != recog_memoized (t2)
4352 || ! rtx_equal_for_thread_p (PATTERN (t1),
4356 t1 = prev_nonnote_insn (t1);
4357 t2 = prev_nonnote_insn (t2);
4364 /* This is like RTX_EQUAL_P except that it knows about our handling of
4365 possibly equivalent registers and knows to consider volatile and
4366 modified objects as not equal.
4368 YINSN is the insn containing Y. */
4371 rtx_equal_for_thread_p (x, y, yinsn)
4377 register enum rtx_code code;
4380 code = GET_CODE (x);
4381 /* Rtx's of different codes cannot be equal. */
4382 if (code != GET_CODE (y))
4385 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4386 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4388 if (GET_MODE (x) != GET_MODE (y))
4391 /* For commutative operations, the RTX match if the operand match in any
4392 order. Also handle the simple binary and unary cases without a loop. */
4393 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4394 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4395 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4396 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4397 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4398 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4399 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4400 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4401 else if (GET_RTX_CLASS (code) == '1')
4402 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4404 /* Handle special-cases first. */
4408 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4411 /* If neither is user variable or hard register, check for possible
4413 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4414 || REGNO (x) < FIRST_PSEUDO_REGISTER
4415 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4418 if (same_regs[REGNO (x)] == -1)
4420 same_regs[REGNO (x)] = REGNO (y);
4423 /* If this is the first time we are seeing a register on the `Y'
4424 side, see if it is the last use. If not, we can't thread the
4425 jump, so mark it as not equivalent. */
4426 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
4432 return (same_regs[REGNO (x)] == REGNO (y));
4437 /* If memory modified or either volatile, not equivalent.
4438 Else, check address. */
4439 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4442 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4445 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4451 /* Cancel a pending `same_regs' if setting equivalenced registers.
4452 Then process source. */
4453 if (GET_CODE (SET_DEST (x)) == REG
4454 && GET_CODE (SET_DEST (y)) == REG)
4456 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4458 same_regs[REGNO (SET_DEST (x))] = -1;
4461 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4465 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4468 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4471 return XEXP (x, 0) == XEXP (y, 0);
4474 return XSTR (x, 0) == XSTR (y, 0);
4480 fmt = GET_RTX_FORMAT (code);
4481 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4486 if (XWINT (x, i) != XWINT (y, i))
4492 if (XINT (x, i) != XINT (y, i))
4498 /* Two vectors must have the same length. */
4499 if (XVECLEN (x, i) != XVECLEN (y, i))
4502 /* And the corresponding elements must match. */
4503 for (j = 0; j < XVECLEN (x, i); j++)
4504 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4505 XVECEXP (y, i, j), yinsn) == 0)
4510 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4516 if (strcmp (XSTR (x, i), XSTR (y, i)))
4521 /* These are just backpointers, so they don't matter. */
4527 /* It is believed that rtx's at this level will never
4528 contain anything but integers and other rtx's,
4529 except for within LABEL_REFs and SYMBOL_REFs. */