1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91, 92, 93, 1994 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This is the jump-optimization pass of the compiler.
22 It is run two or three times: once before cse, sometimes once after cse,
23 and once after reload (before final).
25 jump_optimize deletes unreachable code and labels that are not used.
26 It also deletes jumps that jump to the following insn,
27 and simplifies jumps around unconditional jumps and jumps
28 to unconditional jumps.
30 Each CODE_LABEL has a count of the times it is used
31 stored in the LABEL_NUSES internal field, and each JUMP_INSN
32 has one label that it refers to stored in the
33 JUMP_LABEL internal field. With this we can detect labels that
34 become unused because of the deletion of all the jumps that
35 formerly used them. The JUMP_LABEL info is sometimes looked
38 Optionally, cross-jumping can be done. Currently it is done
39 only the last time (when after reload and before final).
40 In fact, the code for cross-jumping now assumes that register
41 allocation has been done, since it uses `rtx_renumbered_equal_p'.
43 Jump optimization is done after cse when cse's constant-propagation
44 causes jumps to become unconditional or to be deleted.
46 Unreachable loops are not detected here, because the labels
47 have references and the insns appear reachable from the labels.
48 find_basic_blocks in flow.c finds and deletes such loops.
50 The subroutines delete_insn, redirect_jump, and invert_jump are used
51 from other passes as well. */
56 #include "hard-reg-set.h"
59 #include "insn-config.h"
60 #include "insn-flags.h"
63 /* ??? Eventually must record somehow the labels used by jumps
64 from nested functions. */
65 /* Pre-record the next or previous real insn for each label?
66 No, this pass is very fast anyway. */
67 /* Condense consecutive labels?
68 This would make life analysis faster, maybe. */
69 /* Optimize jump y; x: ... y: jumpif... x?
70 Don't know if it is worth bothering with. */
71 /* Optimize two cases of conditional jump to conditional jump?
72 This can never delete any instruction or make anything dead,
73 or even change what is live at any point.
74 So perhaps let combiner do it. */
76 /* Vector indexed by uid.
77 For each CODE_LABEL, index by its uid to get first unconditional jump
78 that jumps to the label.
79 For each JUMP_INSN, index by its uid to get the next unconditional jump
80 that jumps to the same label.
81 Element 0 is the start of a chain of all return insns.
82 (It is safe to use element 0 because insn uid 0 is not used. */
84 static rtx *jump_chain;
86 /* List of labels referred to from initializers.
87 These can never be deleted. */
90 /* Maximum index in jump_chain. */
92 static int max_jump_chain;
94 /* Set nonzero by jump_optimize if control can fall through
95 to the end of the function. */
98 /* Indicates whether death notes are significant in cross jump analysis.
99 Normally they are not significant, because of A and B jump to C,
100 and R dies in A, it must die in B. But this might not be true after
101 stack register conversion, and we must compare death notes in that
104 static int cross_jump_death_matters = 0;
106 static int duplicate_loop_exit_test ();
107 void redirect_tablejump ();
108 static int delete_labelref_insn ();
109 static void mark_jump_label ();
111 void delete_computation ();
112 static void delete_from_jump_chain ();
113 static int tension_vector_labels ();
114 static void find_cross_jump ();
115 static void do_cross_jump ();
116 static int jump_back_p ();
118 extern rtx gen_jump ();
120 /* Delete no-op jumps and optimize jumps to jumps
121 and jumps around jumps.
122 Delete unused labels and unreachable code.
124 If CROSS_JUMP is 1, detect matching code
125 before a jump and its destination and unify them.
126 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
128 If NOOP_MOVES is nonzero, delete no-op move insns.
130 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
131 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
133 If `optimize' is zero, don't change any code,
134 just determine whether control drops off the end of the function.
135 This case occurs when we have -W and not -O.
136 It works because `delete_insn' checks the value of `optimize'
137 and refrains from actually deleting when that is 0. */
140 jump_optimize (f, cross_jump, noop_moves, after_regscan)
146 register rtx insn, next;
152 cross_jump_death_matters = (cross_jump == 2);
154 /* Initialize LABEL_NUSES and JUMP_LABEL fields. */
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 if (INSN_UID (insn) > max_uid)
163 max_uid = INSN_UID (insn);
168 /* Delete insns following barriers, up to next label. */
170 for (insn = f; insn;)
172 if (GET_CODE (insn) == BARRIER)
174 insn = NEXT_INSN (insn);
175 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
177 if (GET_CODE (insn) == NOTE
178 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
179 insn = NEXT_INSN (insn);
181 insn = delete_insn (insn);
183 /* INSN is now the code_label. */
186 insn = NEXT_INSN (insn);
189 /* Leave some extra room for labels and duplicate exit test insns
191 max_jump_chain = max_uid * 14 / 10;
192 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
193 bzero (jump_chain, max_jump_chain * sizeof (rtx));
195 /* Mark the label each jump jumps to.
196 Combine consecutive labels, and count uses of labels.
198 For each label, make a chain (using `jump_chain')
199 of all the *unconditional* jumps that jump to it;
200 also make a chain of all returns. */
202 for (insn = f; insn; insn = NEXT_INSN (insn))
203 if ((GET_CODE (insn) == JUMP_INSN || GET_CODE (insn) == INSN
204 || GET_CODE (insn) == CALL_INSN)
205 && ! INSN_DELETED_P (insn))
207 mark_jump_label (PATTERN (insn), insn, cross_jump);
208 if (GET_CODE (insn) == JUMP_INSN)
210 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
212 jump_chain[INSN_UID (insn)]
213 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
214 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
216 if (GET_CODE (PATTERN (insn)) == RETURN)
218 jump_chain[INSN_UID (insn)] = jump_chain[0];
219 jump_chain[0] = insn;
224 /* Keep track of labels used from static data;
225 they cannot ever be deleted. */
227 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
228 LABEL_NUSES (XEXP (insn, 0))++;
230 /* Delete all labels already not referenced.
231 Also find the last insn. */
234 for (insn = f; insn; )
236 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
237 insn = delete_insn (insn);
241 insn = NEXT_INSN (insn);
247 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
248 If so record that this function can drop off the end. */
254 /* One label can follow the end-note: the return label. */
255 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
256 /* Ordinary insns can follow it if returning a structure. */
257 || GET_CODE (insn) == INSN
258 /* If machine uses explicit RETURN insns, no epilogue,
259 then one of them follows the note. */
260 || (GET_CODE (insn) == JUMP_INSN
261 && GET_CODE (PATTERN (insn)) == RETURN)
262 /* Other kinds of notes can follow also. */
263 || (GET_CODE (insn) == NOTE
264 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
265 insn = PREV_INSN (insn);
268 /* Report if control can fall through at the end of the function. */
269 if (insn && GET_CODE (insn) == NOTE
270 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
271 && ! INSN_DELETED_P (insn))
274 /* Zero the "deleted" flag of all the "deleted" insns. */
275 for (insn = f; insn; insn = NEXT_INSN (insn))
276 INSN_DELETED_P (insn) = 0;
283 /* If we fall through to the epilogue, see if we can insert a RETURN insn
284 in front of it. If the machine allows it at this point (we might be
285 after reload for a leaf routine), it will improve optimization for it
287 insn = get_last_insn ();
288 while (insn && GET_CODE (insn) == NOTE)
289 insn = PREV_INSN (insn);
291 if (insn && GET_CODE (insn) != BARRIER)
293 emit_jump_insn (gen_return ());
300 for (insn = f; insn; )
302 next = NEXT_INSN (insn);
304 if (GET_CODE (insn) == INSN)
306 register rtx body = PATTERN (insn);
308 /* Combine stack_adjusts with following push_insns. */
310 if (GET_CODE (body) == SET
311 && SET_DEST (body) == stack_pointer_rtx
312 && GET_CODE (SET_SRC (body)) == PLUS
313 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
314 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
315 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
318 rtx stack_adjust_insn = insn;
319 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
320 int total_pushed = 0;
323 /* Find all successive push insns. */
325 /* Don't convert more than three pushes;
326 that starts adding too many displaced addresses
327 and the whole thing starts becoming a losing
332 p = next_nonnote_insn (p);
333 if (p == 0 || GET_CODE (p) != INSN)
336 if (GET_CODE (pbody) != SET)
338 dest = SET_DEST (pbody);
339 /* Allow a no-op move between the adjust and the push. */
340 if (GET_CODE (dest) == REG
341 && GET_CODE (SET_SRC (pbody)) == REG
342 && REGNO (dest) == REGNO (SET_SRC (pbody)))
344 if (! (GET_CODE (dest) == MEM
345 && GET_CODE (XEXP (dest, 0)) == POST_INC
346 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
349 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
350 > stack_adjust_amount)
352 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
355 /* Discard the amount pushed from the stack adjust;
356 maybe eliminate it entirely. */
357 if (total_pushed >= stack_adjust_amount)
359 delete_insn (stack_adjust_insn);
360 total_pushed = stack_adjust_amount;
363 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
364 = GEN_INT (stack_adjust_amount - total_pushed);
366 /* Change the appropriate push insns to ordinary stores. */
368 while (total_pushed > 0)
371 p = next_nonnote_insn (p);
372 if (GET_CODE (p) != INSN)
375 if (GET_CODE (pbody) == SET)
377 dest = SET_DEST (pbody);
378 if (! (GET_CODE (dest) == MEM
379 && GET_CODE (XEXP (dest, 0)) == POST_INC
380 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
382 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
383 /* If this push doesn't fully fit in the space
384 of the stack adjust that we deleted,
385 make another stack adjust here for what we
386 didn't use up. There should be peepholes
387 to recognize the resulting sequence of insns. */
388 if (total_pushed < 0)
390 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
391 GEN_INT (- total_pushed)),
396 = plus_constant (stack_pointer_rtx, total_pushed);
401 /* Detect and delete no-op move instructions
402 resulting from not allocating a parameter in a register. */
404 if (GET_CODE (body) == SET
405 && (SET_DEST (body) == SET_SRC (body)
406 || (GET_CODE (SET_DEST (body)) == MEM
407 && GET_CODE (SET_SRC (body)) == MEM
408 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
409 && ! (GET_CODE (SET_DEST (body)) == MEM
410 && MEM_VOLATILE_P (SET_DEST (body)))
411 && ! (GET_CODE (SET_SRC (body)) == MEM
412 && MEM_VOLATILE_P (SET_SRC (body))))
415 /* Detect and ignore no-op move instructions
416 resulting from smart or fortuitous register allocation. */
418 else if (GET_CODE (body) == SET)
420 int sreg = true_regnum (SET_SRC (body));
421 int dreg = true_regnum (SET_DEST (body));
423 if (sreg == dreg && sreg >= 0)
425 else if (sreg >= 0 && dreg >= 0)
428 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
429 sreg, NULL_PTR, dreg,
430 GET_MODE (SET_SRC (body)));
432 #ifdef PRESERVE_DEATH_INFO_REGNO_P
433 /* Deleting insn could lose a death-note for SREG or DREG
434 so don't do it if final needs accurate death-notes. */
435 if (! PRESERVE_DEATH_INFO_REGNO_P (sreg)
436 && ! PRESERVE_DEATH_INFO_REGNO_P (dreg))
439 /* DREG may have been the target of a REG_DEAD note in
440 the insn which makes INSN redundant. If so, reorg
441 would still think it is dead. So search for such a
442 note and delete it if we find it. */
443 for (trial = prev_nonnote_insn (insn);
444 trial && GET_CODE (trial) != CODE_LABEL;
445 trial = prev_nonnote_insn (trial))
446 if (find_regno_note (trial, REG_DEAD, dreg))
448 remove_death (dreg, trial);
453 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
457 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
458 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
460 GET_MODE (SET_DEST (body))))
462 /* This handles the case where we have two consecutive
463 assignments of the same constant to pseudos that didn't
464 get a hard reg. Each SET from the constant will be
465 converted into a SET of the spill register and an
466 output reload will be made following it. This produces
467 two loads of the same constant into the same spill
472 /* Look back for a death note for the first reg.
473 If there is one, it is no longer accurate. */
474 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
476 if ((GET_CODE (in_insn) == INSN
477 || GET_CODE (in_insn) == JUMP_INSN)
478 && find_regno_note (in_insn, REG_DEAD, dreg))
480 remove_death (dreg, in_insn);
483 in_insn = PREV_INSN (in_insn);
486 /* Delete the second load of the value. */
490 else if (GET_CODE (body) == PARALLEL)
492 /* If each part is a set between two identical registers or
493 a USE or CLOBBER, delete the insn. */
497 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
499 tem = XVECEXP (body, 0, i);
500 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
503 if (GET_CODE (tem) != SET
504 || (sreg = true_regnum (SET_SRC (tem))) < 0
505 || (dreg = true_regnum (SET_DEST (tem))) < 0
513 #if !BYTES_BIG_ENDIAN /* Not worth the hair to detect this
514 in the big-endian case. */
515 /* Also delete insns to store bit fields if they are no-ops. */
516 else if (GET_CODE (body) == SET
517 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
518 && XEXP (SET_DEST (body), 2) == const0_rtx
519 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
520 && ! (GET_CODE (SET_SRC (body)) == MEM
521 && MEM_VOLATILE_P (SET_SRC (body))))
523 #endif /* not BYTES_BIG_ENDIAN */
528 /* If we haven't yet gotten to reload and we have just run regscan,
529 delete any insn that sets a register that isn't used elsewhere.
530 This helps some of the optimizations below by having less insns
531 being jumped around. */
533 if (! reload_completed && after_regscan)
534 for (insn = f; insn; insn = next)
536 rtx set = single_set (insn);
538 next = NEXT_INSN (insn);
540 if (set && GET_CODE (SET_DEST (set)) == REG
541 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
542 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
543 /* We use regno_last_note_uid so as not to delete the setting
544 of a reg that's used in notes. A subsequent optimization
545 might arrange to use that reg for real. */
546 && regno_last_note_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
547 && ! side_effects_p (SET_SRC (set)))
551 /* Now iterate optimizing jumps until nothing changes over one pass. */
557 for (insn = f; insn; insn = next)
560 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
562 int this_is_simplejump, this_is_condjump, reversep;
564 /* If NOT the first iteration, if this is the last jump pass
565 (just before final), do the special peephole optimizations.
566 Avoiding the first iteration gives ordinary jump opts
567 a chance to work before peephole opts. */
569 if (reload_completed && !first && !flag_no_peephole)
570 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
574 /* That could have deleted some insns after INSN, so check now
575 what the following insn is. */
577 next = NEXT_INSN (insn);
579 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
580 jump. Try to optimize by duplicating the loop exit test if so.
581 This is only safe immediately after regscan, because it uses
582 the values of regno_first_uid and regno_last_uid. */
583 if (after_regscan && GET_CODE (insn) == NOTE
584 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
585 && (temp1 = next_nonnote_insn (insn)) != 0
586 && simplejump_p (temp1))
588 temp = PREV_INSN (insn);
589 if (duplicate_loop_exit_test (insn))
592 next = NEXT_INSN (temp);
597 if (GET_CODE (insn) != JUMP_INSN)
600 this_is_simplejump = simplejump_p (insn);
601 this_is_condjump = condjump_p (insn);
603 /* Tension the labels in dispatch tables. */
605 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
606 changed |= tension_vector_labels (PATTERN (insn), 0);
607 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
608 changed |= tension_vector_labels (PATTERN (insn), 1);
610 /* If a dispatch table always goes to the same place,
611 get rid of it and replace the insn that uses it. */
613 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
614 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
617 rtx pat = PATTERN (insn);
618 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
619 int len = XVECLEN (pat, diff_vec_p);
620 rtx dispatch = prev_real_insn (insn);
622 for (i = 0; i < len; i++)
623 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
624 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
628 && GET_CODE (dispatch) == JUMP_INSN
629 && JUMP_LABEL (dispatch) != 0
630 /* Don't mess with a casesi insn. */
631 && !(GET_CODE (PATTERN (dispatch)) == SET
632 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
634 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
636 redirect_tablejump (dispatch,
637 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
642 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
644 /* If a jump references the end of the function, try to turn
645 it into a RETURN insn, possibly a conditional one. */
646 if (JUMP_LABEL (insn)
647 && (next_active_insn (JUMP_LABEL (insn)) == 0
648 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
650 changed |= redirect_jump (insn, NULL_RTX);
652 /* Detect jump to following insn. */
653 if (reallabelprev == insn && condjump_p (insn))
660 /* If we have an unconditional jump preceded by a USE, try to put
661 the USE before the target and jump there. This simplifies many
662 of the optimizations below since we don't have to worry about
663 dealing with these USE insns. We only do this if the label
664 being branch to already has the identical USE or if code
665 never falls through to that label. */
667 if (this_is_simplejump
668 && (temp = prev_nonnote_insn (insn)) != 0
669 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
670 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
671 && (GET_CODE (temp1) == BARRIER
672 || (GET_CODE (temp1) == INSN
673 && rtx_equal_p (PATTERN (temp), PATTERN (temp1)))))
675 if (GET_CODE (temp1) == BARRIER)
677 emit_insn_after (PATTERN (temp), temp1);
678 temp1 = NEXT_INSN (temp1);
682 redirect_jump (insn, get_label_before (temp1));
683 reallabelprev = prev_real_insn (temp1);
687 /* Simplify if (...) x = a; else x = b; by converting it
688 to x = b; if (...) x = a;
689 if B is sufficiently simple, the test doesn't involve X,
690 and nothing in the test modifies B or X.
692 If we have small register classes, we also can't do this if X
695 If the "x = b;" insn has any REG_NOTES, we don't do this because
696 of the possibility that we are running after CSE and there is a
697 REG_EQUAL note that is only valid if the branch has already been
698 taken. If we move the insn with the REG_EQUAL note, we may
699 fold the comparison to always be false in a later CSE pass.
700 (We could also delete the REG_NOTES when moving the insn, but it
701 seems simpler to not move it.) An exception is that we can move
702 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
703 value is the same as "b".
705 INSN is the branch over the `else' part.
709 TEMP to the jump insn preceding "x = a;"
711 TEMP2 to the insn that sets "x = b;"
712 TEMP3 to the insn that sets "x = a;"
713 TEMP4 to the set of "x = b"; */
715 if (this_is_simplejump
716 && (temp3 = prev_active_insn (insn)) != 0
717 && GET_CODE (temp3) == INSN
718 && (temp4 = single_set (temp3)) != 0
719 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
720 #ifdef SMALL_REGISTER_CLASSES
721 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
723 && (temp2 = next_active_insn (insn)) != 0
724 && GET_CODE (temp2) == INSN
725 && (temp4 = single_set (temp2)) != 0
726 && rtx_equal_p (SET_DEST (temp4), temp1)
727 && (GET_CODE (SET_SRC (temp4)) == REG
728 || GET_CODE (SET_SRC (temp4)) == SUBREG
729 || CONSTANT_P (SET_SRC (temp4)))
730 && (REG_NOTES (temp2) == 0
731 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
732 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
733 && XEXP (REG_NOTES (temp2), 1) == 0
734 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
736 && (temp = prev_active_insn (temp3)) != 0
737 && condjump_p (temp) && ! simplejump_p (temp)
738 /* TEMP must skip over the "x = a;" insn */
739 && prev_real_insn (JUMP_LABEL (temp)) == insn
740 && no_labels_between_p (insn, JUMP_LABEL (temp))
741 /* There must be no other entries to the "x = b;" insn. */
742 && no_labels_between_p (JUMP_LABEL (temp), temp2)
743 /* INSN must either branch to the insn after TEMP2 or the insn
744 after TEMP2 must branch to the same place as INSN. */
745 && (reallabelprev == temp2
746 || ((temp5 = next_active_insn (temp2)) != 0
747 && simplejump_p (temp5)
748 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
750 /* The test expression, X, may be a complicated test with
751 multiple branches. See if we can find all the uses of
752 the label that TEMP branches to without hitting a CALL_INSN
753 or a jump to somewhere else. */
754 rtx target = JUMP_LABEL (temp);
755 int nuses = LABEL_NUSES (target);
758 /* Set P to the first jump insn that goes around "x = a;". */
759 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
761 if (GET_CODE (p) == JUMP_INSN)
763 if (condjump_p (p) && ! simplejump_p (p)
764 && JUMP_LABEL (p) == target)
773 else if (GET_CODE (p) == CALL_INSN)
778 /* We cannot insert anything between a set of cc and its use
779 so if P uses cc0, we must back up to the previous insn. */
780 q = prev_nonnote_insn (p);
781 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
782 && sets_cc0_p (PATTERN (q)))
789 /* If we found all the uses and there was no data conflict, we
790 can move the assignment unless we can branch into the middle
793 && no_labels_between_p (p, insn)
794 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
795 && ! reg_set_between_p (temp1, p, temp3)
796 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
797 || ! reg_set_between_p (SET_SRC (temp4), p, temp2)))
799 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
802 /* Set NEXT to an insn that we know won't go away. */
803 next = next_active_insn (insn);
805 /* Delete the jump around the set. Note that we must do
806 this before we redirect the test jumps so that it won't
807 delete the code immediately following the assignment
808 we moved (which might be a jump). */
812 /* We either have two consecutive labels or a jump to
813 a jump, so adjust all the JUMP_INSNs to branch to where
815 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
816 if (GET_CODE (p) == JUMP_INSN)
817 redirect_jump (p, target);
825 /* If we have if (...) x = exp; and branches are expensive,
826 EXP is a single insn, does not have any side effects, cannot
827 trap, and is not too costly, convert this to
828 t = exp; if (...) x = t;
830 Don't do this when we have CC0 because it is unlikely to help
831 and we'd need to worry about where to place the new insn and
832 the potential for conflicts. We also can't do this when we have
833 notes on the insn for the same reason as above.
837 TEMP to the "x = exp;" insn.
838 TEMP1 to the single set in the "x = exp; insn.
841 if (! reload_completed
842 && this_is_condjump && ! this_is_simplejump
844 && (temp = next_nonnote_insn (insn)) != 0
845 && GET_CODE (temp) == INSN
846 && REG_NOTES (temp) == 0
847 && (reallabelprev == temp
848 || ((temp2 = next_active_insn (temp)) != 0
849 && simplejump_p (temp2)
850 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
851 && (temp1 = single_set (temp)) != 0
852 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
853 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
854 #ifdef SMALL_REGISTER_CLASSES
855 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
857 && GET_CODE (SET_SRC (temp1)) != REG
858 && GET_CODE (SET_SRC (temp1)) != SUBREG
859 && GET_CODE (SET_SRC (temp1)) != CONST_INT
860 && ! side_effects_p (SET_SRC (temp1))
861 && ! may_trap_p (SET_SRC (temp1))
862 && rtx_cost (SET_SRC (temp1)) < 10)
864 rtx new = gen_reg_rtx (GET_MODE (temp2));
866 if (validate_change (temp, &SET_DEST (temp1), new, 0))
868 next = emit_insn_after (gen_move_insn (temp2, new), insn);
869 emit_insn_after_with_line_notes (PATTERN (temp),
870 PREV_INSN (insn), temp);
872 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
876 /* Similarly, if it takes two insns to compute EXP but they
877 have the same destination. Here TEMP3 will be the second
878 insn and TEMP4 the SET from that insn. */
880 if (! reload_completed
881 && this_is_condjump && ! this_is_simplejump
883 && (temp = next_nonnote_insn (insn)) != 0
884 && GET_CODE (temp) == INSN
885 && REG_NOTES (temp) == 0
886 && (temp3 = next_nonnote_insn (temp)) != 0
887 && GET_CODE (temp3) == INSN
888 && REG_NOTES (temp3) == 0
889 && (reallabelprev == temp3
890 || ((temp2 = next_active_insn (temp3)) != 0
891 && simplejump_p (temp2)
892 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
893 && (temp1 = single_set (temp)) != 0
894 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
895 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
896 #ifdef SMALL_REGISTER_CLASSES
897 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
899 && ! side_effects_p (SET_SRC (temp1))
900 && ! may_trap_p (SET_SRC (temp1))
901 && rtx_cost (SET_SRC (temp1)) < 10
902 && (temp4 = single_set (temp3)) != 0
903 && rtx_equal_p (SET_DEST (temp4), temp2)
904 && ! side_effects_p (SET_SRC (temp4))
905 && ! may_trap_p (SET_SRC (temp4))
906 && rtx_cost (SET_SRC (temp4)) < 10)
908 rtx new = gen_reg_rtx (GET_MODE (temp2));
910 if (validate_change (temp, &SET_DEST (temp1), new, 0))
912 next = emit_insn_after (gen_move_insn (temp2, new), insn);
913 emit_insn_after_with_line_notes (PATTERN (temp),
914 PREV_INSN (insn), temp);
915 emit_insn_after_with_line_notes
916 (replace_rtx (PATTERN (temp3), temp2, new),
917 PREV_INSN (insn), temp3);
920 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
924 /* Finally, handle the case where two insns are used to
925 compute EXP but a temporary register is used. Here we must
926 ensure that the temporary register is not used anywhere else. */
928 if (! reload_completed
930 && this_is_condjump && ! this_is_simplejump
932 && (temp = next_nonnote_insn (insn)) != 0
933 && GET_CODE (temp) == INSN
934 && REG_NOTES (temp) == 0
935 && (temp3 = next_nonnote_insn (temp)) != 0
936 && GET_CODE (temp3) == INSN
937 && REG_NOTES (temp3) == 0
938 && (reallabelprev == temp3
939 || ((temp2 = next_active_insn (temp3)) != 0
940 && simplejump_p (temp2)
941 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
942 && (temp1 = single_set (temp)) != 0
943 && (temp5 = SET_DEST (temp1), GET_CODE (temp5) == REG)
944 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
945 && regno_first_uid[REGNO (temp5)] == INSN_UID (temp)
946 && regno_last_uid[REGNO (temp5)] == INSN_UID (temp3)
947 && ! side_effects_p (SET_SRC (temp1))
948 && ! may_trap_p (SET_SRC (temp1))
949 && rtx_cost (SET_SRC (temp1)) < 10
950 && (temp4 = single_set (temp3)) != 0
951 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
952 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
953 #ifdef SMALL_REGISTER_CLASSES
954 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
956 && rtx_equal_p (SET_DEST (temp4), temp2)
957 && ! side_effects_p (SET_SRC (temp4))
958 && ! may_trap_p (SET_SRC (temp4))
959 && rtx_cost (SET_SRC (temp4)) < 10)
961 rtx new = gen_reg_rtx (GET_MODE (temp2));
963 if (validate_change (temp3, &SET_DEST (temp4), new, 0))
965 next = emit_insn_after (gen_move_insn (temp2, new), insn);
966 emit_insn_after_with_line_notes (PATTERN (temp),
967 PREV_INSN (insn), temp);
968 emit_insn_after_with_line_notes (PATTERN (temp3),
969 PREV_INSN (insn), temp3);
972 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
975 #endif /* HAVE_cc0 */
977 /* We deal with four cases:
979 1) x = a; if (...) x = b; and either A or B is zero,
980 2) if (...) x = 0; and jumps are expensive,
981 3) x = a; if (...) x = b; and A and B are constants where all the
982 set bits in A are also set in B and jumps are expensive, and
983 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
985 5) if (...) x = b; if jumps are even more expensive.
987 In each of these try to use a store-flag insn to avoid the jump.
988 (If the jump would be faster, the machine should not have
989 defined the scc insns!). These cases are often made by the
990 previous optimization.
992 INSN here is the jump around the store. We set:
994 TEMP to the "x = b;" insn.
996 TEMP2 to B (const0_rtx in the second case).
997 TEMP3 to A (X in the second case).
998 TEMP4 to the condition being tested.
999 TEMP5 to the earliest insn used to find the condition. */
1001 if (/* We can't do this after reload has completed. */
1003 && this_is_condjump && ! this_is_simplejump
1004 /* Set TEMP to the "x = b;" insn. */
1005 && (temp = next_nonnote_insn (insn)) != 0
1006 && GET_CODE (temp) == INSN
1007 && GET_CODE (PATTERN (temp)) == SET
1008 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1009 #ifdef SMALL_REGISTER_CLASSES
1010 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
1012 && GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1013 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1014 || GET_CODE (temp2) == SUBREG
1015 || GET_CODE (temp2) == CONST_INT)
1016 /* Allow either form, but prefer the former if both apply.
1017 There is no point in using the old value of TEMP1 if
1018 it is a register, since cse will alias them. It can
1019 lose if the old value were a hard register since CSE
1020 won't replace hard registers. */
1021 && (((temp3 = reg_set_last (temp1, insn)) != 0
1022 && GET_CODE (temp3) == CONST_INT)
1023 /* Make the latter case look like x = x; if (...) x = 0; */
1026 && temp2 == const0_rtx)
1027 #ifdef HAVE_conditional_move
1030 || BRANCH_COST >= 3)))
1031 /* INSN must either branch to the insn after TEMP or the insn
1032 after TEMP must branch to the same place as INSN. */
1033 && (reallabelprev == temp
1034 || ((temp4 = next_active_insn (temp)) != 0
1035 && simplejump_p (temp4)
1036 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1037 && (temp4 = get_condition (insn, &temp5)) != 0
1038 /* We must be comparing objects whose modes imply the size.
1039 We could handle BLKmode if (1) emit_store_flag could
1040 and (2) we could find the size reliably. */
1041 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1043 /* If B is zero, OK; if A is zero, can only do (1) if we
1044 can reverse the condition. See if (3) applies possibly
1045 by reversing the condition. Prefer reversing to (4) when
1046 branches are very expensive. */
1047 && ((reversep = 0, temp2 == const0_rtx)
1048 || (temp3 == const0_rtx
1049 && (reversep = can_reverse_comparison_p (temp4, insn)))
1050 || (BRANCH_COST >= 2
1051 && GET_CODE (temp2) == CONST_INT
1052 && GET_CODE (temp3) == CONST_INT
1053 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1054 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1055 && (reversep = can_reverse_comparison_p (temp4,
1057 #ifdef HAVE_conditional_move
1060 || BRANCH_COST >= 3)
1062 /* If the previous insn sets CC0 and something else, we can't
1063 do this since we are going to delete that insn. */
1065 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1066 && GET_CODE (temp6) == INSN
1067 && (sets_cc0_p (PATTERN (temp6)) == -1
1068 || (sets_cc0_p (PATTERN (temp6)) == 1
1069 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1073 enum rtx_code code = GET_CODE (temp4);
1074 rtx uval, cval, var = temp1;
1078 /* If necessary, reverse the condition. */
1080 code = reverse_condition (code), uval = temp2, cval = temp3;
1082 uval = temp3, cval = temp2;
1084 /* See if we can do this with a store-flag insn. */
1087 /* If CVAL is non-zero, normalize to -1. Otherwise,
1088 if UVAL is the constant 1, it is best to just compute
1089 the result directly. If UVAL is constant and STORE_FLAG_VALUE
1090 includes all of its bits, it is best to compute the flag
1091 value unnormalized and `and' it with UVAL. Otherwise,
1092 normalize to -1 and `and' with UVAL. */
1093 normalizep = (cval != const0_rtx ? -1
1094 : (uval == const1_rtx ? 1
1095 : (GET_CODE (uval) == CONST_INT
1096 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1099 /* We will be putting the store-flag insn immediately in
1100 front of the comparison that was originally being done,
1101 so we know all the variables in TEMP4 will be valid.
1102 However, this might be in front of the assignment of
1103 A to VAR. If it is, it would clobber the store-flag
1104 we will be emitting.
1106 Therefore, emit into a temporary which will be copied to
1107 VAR immediately after TEMP. */
1109 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1110 XEXP (temp4, 0), XEXP (temp4, 1),
1112 (code == LTU || code == LEU
1113 || code == GEU || code == GTU),
1120 /* Put the store-flag insns in front of the first insn
1121 used to compute the condition to ensure that we
1122 use the same values of them as the current
1123 comparison. However, the remainder of the insns we
1124 generate will be placed directly in front of the
1125 jump insn, in case any of the pseudos we use
1126 are modified earlier. */
1131 emit_insns_before (seq, temp5);
1135 /* Both CVAL and UVAL are non-zero. */
1136 if (cval != const0_rtx && uval != const0_rtx)
1140 tem1 = expand_and (uval, target, NULL_RTX);
1141 if (GET_CODE (cval) == CONST_INT
1142 && GET_CODE (uval) == CONST_INT
1143 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1147 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1148 target, NULL_RTX, 0);
1149 tem2 = expand_and (cval, tem2,
1150 (GET_CODE (tem2) == REG
1154 /* If we usually make new pseudos, do so here. This
1155 turns out to help machines that have conditional
1158 if (flag_expensive_optimizations)
1161 target = expand_binop (GET_MODE (var), ior_optab,
1165 else if (normalizep != 1)
1167 /* We know that either CVAL or UVAL is zero. If
1168 UVAL is zero, negate TARGET and `and' with CVAL.
1169 Otherwise, `and' with UVAL. */
1170 if (uval == const0_rtx)
1172 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1173 target, NULL_RTX, 0);
1177 target = expand_and (uval, target,
1178 (GET_CODE (target) == REG
1179 && ! preserve_subexpressions_p ()
1180 ? target : NULL_RTX));
1183 emit_move_insn (var, target);
1188 /* If INSN uses CC0, we must not separate it from the
1189 insn that sets cc0. */
1191 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1192 before = prev_nonnote_insn (before);
1195 emit_insns_before (seq, before);
1198 next = NEXT_INSN (insn);
1208 /* If branches are expensive, convert
1209 if (foo) bar++; to bar += (foo != 0);
1210 and similarly for "bar--;"
1212 INSN is the conditional branch around the arithmetic. We set:
1214 TEMP is the arithmetic insn.
1215 TEMP1 is the SET doing the arithmetic.
1216 TEMP2 is the operand being incremented or decremented.
1217 TEMP3 to the condition being tested.
1218 TEMP4 to the earliest insn used to find the condition. */
1220 if ((BRANCH_COST >= 2
1228 && ! reload_completed
1229 && this_is_condjump && ! this_is_simplejump
1230 && (temp = next_nonnote_insn (insn)) != 0
1231 && (temp1 = single_set (temp)) != 0
1232 && (temp2 = SET_DEST (temp1),
1233 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1234 && GET_CODE (SET_SRC (temp1)) == PLUS
1235 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1236 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1237 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1238 /* INSN must either branch to the insn after TEMP or the insn
1239 after TEMP must branch to the same place as INSN. */
1240 && (reallabelprev == temp
1241 || ((temp3 = next_active_insn (temp)) != 0
1242 && simplejump_p (temp3)
1243 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1244 && (temp3 = get_condition (insn, &temp4)) != 0
1245 /* We must be comparing objects whose modes imply the size.
1246 We could handle BLKmode if (1) emit_store_flag could
1247 and (2) we could find the size reliably. */
1248 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1249 && can_reverse_comparison_p (temp3, insn))
1251 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1252 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1256 /* It must be the case that TEMP2 is not modified in the range
1257 [TEMP4, INSN). The one exception we make is if the insn
1258 before INSN sets TEMP2 to something which is also unchanged
1259 in that range. In that case, we can move the initialization
1260 into our sequence. */
1262 if ((temp5 = prev_active_insn (insn)) != 0
1263 && GET_CODE (temp5) == INSN
1264 && (temp6 = single_set (temp5)) != 0
1265 && rtx_equal_p (temp2, SET_DEST (temp6))
1266 && (CONSTANT_P (SET_SRC (temp6))
1267 || GET_CODE (SET_SRC (temp6)) == REG
1268 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1270 emit_insn (PATTERN (temp5));
1272 init = SET_SRC (temp6);
1275 if (CONSTANT_P (init)
1276 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1277 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1278 XEXP (temp3, 0), XEXP (temp3, 1),
1280 (code == LTU || code == LEU
1281 || code == GTU || code == GEU), 1);
1283 /* If we can do the store-flag, do the addition or
1287 target = expand_binop (GET_MODE (temp2),
1288 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1289 ? add_optab : sub_optab),
1290 temp2, target, temp2, 0, OPTAB_WIDEN);
1294 /* Put the result back in temp2 in case it isn't already.
1295 Then replace the jump, possible a CC0-setting insn in
1296 front of the jump, and TEMP, with the sequence we have
1299 if (target != temp2)
1300 emit_move_insn (temp2, target);
1305 emit_insns_before (seq, temp4);
1309 delete_insn (init_insn);
1311 next = NEXT_INSN (insn);
1313 delete_insn (prev_nonnote_insn (insn));
1323 /* Simplify if (...) x = 1; else {...} if (x) ...
1324 We recognize this case scanning backwards as well.
1326 TEMP is the assignment to x;
1327 TEMP1 is the label at the head of the second if. */
1328 /* ?? This should call get_condition to find the values being
1329 compared, instead of looking for a COMPARE insn when HAVE_cc0
1330 is not defined. This would allow it to work on the m88k. */
1331 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1332 is not defined and the condition is tested by a separate compare
1333 insn. This is because the code below assumes that the result
1334 of the compare dies in the following branch.
1336 Not only that, but there might be other insns between the
1337 compare and branch whose results are live. Those insns need
1340 A way to fix this is to move the insns at JUMP_LABEL (insn)
1341 to before INSN. If we are running before flow, they will
1342 be deleted if they aren't needed. But this doesn't work
1345 This is really a special-case of jump threading, anyway. The
1346 right thing to do is to replace this and jump threading with
1347 much simpler code in cse.
1349 This code has been turned off in the non-cc0 case in the
1353 else if (this_is_simplejump
1354 /* Safe to skip USE and CLOBBER insns here
1355 since they will not be deleted. */
1356 && (temp = prev_active_insn (insn))
1357 && no_labels_between_p (temp, insn)
1358 && GET_CODE (temp) == INSN
1359 && GET_CODE (PATTERN (temp)) == SET
1360 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1361 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1362 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1363 /* If we find that the next value tested is `x'
1364 (TEMP1 is the insn where this happens), win. */
1365 && GET_CODE (temp1) == INSN
1366 && GET_CODE (PATTERN (temp1)) == SET
1368 /* Does temp1 `tst' the value of x? */
1369 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1370 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1371 && (temp1 = next_nonnote_insn (temp1))
1373 /* Does temp1 compare the value of x against zero? */
1374 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1375 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1376 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1377 == SET_DEST (PATTERN (temp)))
1378 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1379 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1381 && condjump_p (temp1))
1383 /* Get the if_then_else from the condjump. */
1384 rtx choice = SET_SRC (PATTERN (temp1));
1385 if (GET_CODE (choice) == IF_THEN_ELSE)
1387 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1388 rtx val = SET_SRC (PATTERN (temp));
1390 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1394 if (cond == const_true_rtx)
1395 ultimate = XEXP (choice, 1);
1396 else if (cond == const0_rtx)
1397 ultimate = XEXP (choice, 2);
1401 if (ultimate == pc_rtx)
1402 ultimate = get_label_after (temp1);
1403 else if (ultimate && GET_CODE (ultimate) != RETURN)
1404 ultimate = XEXP (ultimate, 0);
1407 changed |= redirect_jump (insn, ultimate);
1413 /* @@ This needs a bit of work before it will be right.
1415 Any type of comparison can be accepted for the first and
1416 second compare. When rewriting the first jump, we must
1417 compute the what conditions can reach label3, and use the
1418 appropriate code. We can not simply reverse/swap the code
1419 of the first jump. In some cases, the second jump must be
1423 < == converts to > ==
1424 < != converts to == >
1427 If the code is written to only accept an '==' test for the second
1428 compare, then all that needs to be done is to swap the condition
1429 of the first branch.
1431 It is questionable whether we want this optimization anyways,
1432 since if the user wrote code like this because he/she knew that
1433 the jump to label1 is taken most of the time, then rewriting
1434 this gives slower code. */
1435 /* @@ This should call get_condition to find the values being
1436 compared, instead of looking for a COMPARE insn when HAVE_cc0
1437 is not defined. This would allow it to work on the m88k. */
1438 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1439 is not defined and the condition is tested by a separate compare
1440 insn. This is because the code below assumes that the result
1441 of the compare dies in the following branch. */
1443 /* Simplify test a ~= b
1457 where ~= is an inequality, e.g. >, and ~~= is the swapped
1460 We recognize this case scanning backwards.
1462 TEMP is the conditional jump to `label2';
1463 TEMP1 is the test for `a == b';
1464 TEMP2 is the conditional jump to `label1';
1465 TEMP3 is the test for `a ~= b'. */
1466 else if (this_is_simplejump
1467 && (temp = prev_active_insn (insn))
1468 && no_labels_between_p (temp, insn)
1469 && condjump_p (temp)
1470 && (temp1 = prev_active_insn (temp))
1471 && no_labels_between_p (temp1, temp)
1472 && GET_CODE (temp1) == INSN
1473 && GET_CODE (PATTERN (temp1)) == SET
1475 && sets_cc0_p (PATTERN (temp1)) == 1
1477 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1478 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1479 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1481 && (temp2 = prev_active_insn (temp1))
1482 && no_labels_between_p (temp2, temp1)
1483 && condjump_p (temp2)
1484 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1485 && (temp3 = prev_active_insn (temp2))
1486 && no_labels_between_p (temp3, temp2)
1487 && GET_CODE (PATTERN (temp3)) == SET
1488 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1489 SET_DEST (PATTERN (temp1)))
1490 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1491 SET_SRC (PATTERN (temp3)))
1492 && ! inequality_comparisons_p (PATTERN (temp))
1493 && inequality_comparisons_p (PATTERN (temp2)))
1495 rtx fallthrough_label = JUMP_LABEL (temp2);
1497 ++LABEL_NUSES (fallthrough_label);
1498 if (swap_jump (temp2, JUMP_LABEL (insn)))
1504 if (--LABEL_NUSES (fallthrough_label) == 0)
1505 delete_insn (fallthrough_label);
1508 /* Simplify if (...) {... x = 1;} if (x) ...
1510 We recognize this case backwards.
1512 TEMP is the test of `x';
1513 TEMP1 is the assignment to `x' at the end of the
1514 previous statement. */
1515 /* @@ This should call get_condition to find the values being
1516 compared, instead of looking for a COMPARE insn when HAVE_cc0
1517 is not defined. This would allow it to work on the m88k. */
1518 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1519 is not defined and the condition is tested by a separate compare
1520 insn. This is because the code below assumes that the result
1521 of the compare dies in the following branch. */
1523 /* ??? This has to be turned off. The problem is that the
1524 unconditional jump might indirectly end up branching to the
1525 label between TEMP1 and TEMP. We can't detect this, in general,
1526 since it may become a jump to there after further optimizations.
1527 If that jump is done, it will be deleted, so we will retry
1528 this optimization in the next pass, thus an infinite loop.
1530 The present code prevents this by putting the jump after the
1531 label, but this is not logically correct. */
1533 else if (this_is_condjump
1534 /* Safe to skip USE and CLOBBER insns here
1535 since they will not be deleted. */
1536 && (temp = prev_active_insn (insn))
1537 && no_labels_between_p (temp, insn)
1538 && GET_CODE (temp) == INSN
1539 && GET_CODE (PATTERN (temp)) == SET
1541 && sets_cc0_p (PATTERN (temp)) == 1
1542 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1544 /* Temp must be a compare insn, we can not accept a register
1545 to register move here, since it may not be simply a
1547 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1548 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1549 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1550 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1551 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1553 /* May skip USE or CLOBBER insns here
1554 for checking for opportunity, since we
1555 take care of them later. */
1556 && (temp1 = prev_active_insn (temp))
1557 && GET_CODE (temp1) == INSN
1558 && GET_CODE (PATTERN (temp1)) == SET
1560 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1562 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1563 == SET_DEST (PATTERN (temp1)))
1565 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1566 /* If this isn't true, cse will do the job. */
1567 && ! no_labels_between_p (temp1, temp))
1569 /* Get the if_then_else from the condjump. */
1570 rtx choice = SET_SRC (PATTERN (insn));
1571 if (GET_CODE (choice) == IF_THEN_ELSE
1572 && (GET_CODE (XEXP (choice, 0)) == EQ
1573 || GET_CODE (XEXP (choice, 0)) == NE))
1575 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1580 /* Get the place that condjump will jump to
1581 if it is reached from here. */
1582 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1584 ultimate = XEXP (choice, 1);
1586 ultimate = XEXP (choice, 2);
1587 /* Get it as a CODE_LABEL. */
1588 if (ultimate == pc_rtx)
1589 ultimate = get_label_after (insn);
1591 /* Get the label out of the LABEL_REF. */
1592 ultimate = XEXP (ultimate, 0);
1594 /* Insert the jump immediately before TEMP, specifically
1595 after the label that is between TEMP1 and TEMP. */
1596 last_insn = PREV_INSN (temp);
1598 /* If we would be branching to the next insn, the jump
1599 would immediately be deleted and the re-inserted in
1600 a subsequent pass over the code. So don't do anything
1602 if (next_active_insn (last_insn)
1603 != next_active_insn (ultimate))
1605 emit_barrier_after (last_insn);
1606 p = emit_jump_insn_after (gen_jump (ultimate),
1608 JUMP_LABEL (p) = ultimate;
1609 ++LABEL_NUSES (ultimate);
1610 if (INSN_UID (ultimate) < max_jump_chain
1611 && INSN_CODE (p) < max_jump_chain)
1613 jump_chain[INSN_UID (p)]
1614 = jump_chain[INSN_UID (ultimate)];
1615 jump_chain[INSN_UID (ultimate)] = p;
1623 /* Detect a conditional jump going to the same place
1624 as an immediately following unconditional jump. */
1625 else if (this_is_condjump
1626 && (temp = next_active_insn (insn)) != 0
1627 && simplejump_p (temp)
1628 && (next_active_insn (JUMP_LABEL (insn))
1629 == next_active_insn (JUMP_LABEL (temp))))
1635 /* Detect a conditional jump jumping over an unconditional jump. */
1637 else if (this_is_condjump && ! this_is_simplejump
1638 && reallabelprev != 0
1639 && GET_CODE (reallabelprev) == JUMP_INSN
1640 && prev_active_insn (reallabelprev) == insn
1641 && no_labels_between_p (insn, reallabelprev)
1642 && simplejump_p (reallabelprev))
1644 /* When we invert the unconditional jump, we will be
1645 decrementing the usage count of its old label.
1646 Make sure that we don't delete it now because that
1647 might cause the following code to be deleted. */
1648 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1649 rtx prev_label = JUMP_LABEL (insn);
1652 ++LABEL_NUSES (prev_label);
1654 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1656 /* It is very likely that if there are USE insns before
1657 this jump, they hold REG_DEAD notes. These REG_DEAD
1658 notes are no longer valid due to this optimization,
1659 and will cause the life-analysis that following passes
1660 (notably delayed-branch scheduling) to think that
1661 these registers are dead when they are not.
1663 To prevent this trouble, we just remove the USE insns
1664 from the insn chain. */
1666 while (prev_uses && GET_CODE (prev_uses) == INSN
1667 && GET_CODE (PATTERN (prev_uses)) == USE)
1669 rtx useless = prev_uses;
1670 prev_uses = prev_nonnote_insn (prev_uses);
1671 delete_insn (useless);
1674 delete_insn (reallabelprev);
1679 /* We can now safely delete the label if it is unreferenced
1680 since the delete_insn above has deleted the BARRIER. */
1681 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1682 delete_insn (prev_label);
1687 /* Detect a jump to a jump. */
1689 nlabel = follow_jumps (JUMP_LABEL (insn));
1690 if (nlabel != JUMP_LABEL (insn)
1691 && redirect_jump (insn, nlabel))
1697 /* Look for if (foo) bar; else break; */
1698 /* The insns look like this:
1699 insn = condjump label1;
1700 ...range1 (some insns)...
1703 ...range2 (some insns)...
1704 jump somewhere unconditionally
1707 rtx label1 = next_label (insn);
1708 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1709 /* Don't do this optimization on the first round, so that
1710 jump-around-a-jump gets simplified before we ask here
1711 whether a jump is unconditional.
1713 Also don't do it when we are called after reload since
1714 it will confuse reorg. */
1716 && (reload_completed ? ! flag_delayed_branch : 1)
1717 /* Make sure INSN is something we can invert. */
1718 && condjump_p (insn)
1720 && JUMP_LABEL (insn) == label1
1721 && LABEL_NUSES (label1) == 1
1722 && GET_CODE (range1end) == JUMP_INSN
1723 && simplejump_p (range1end))
1725 rtx label2 = next_label (label1);
1726 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1727 if (range1end != range2end
1728 && JUMP_LABEL (range1end) == label2
1729 && GET_CODE (range2end) == JUMP_INSN
1730 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1731 /* Invert the jump condition, so we
1732 still execute the same insns in each case. */
1733 && invert_jump (insn, label1))
1735 rtx range1beg = next_active_insn (insn);
1736 rtx range2beg = next_active_insn (label1);
1737 rtx range1after, range2after;
1738 rtx range1before, range2before;
1740 /* Include in each range any notes before it, to be
1741 sure that we get the line number note if any, even
1742 if there are other notes here. */
1743 while (PREV_INSN (range1beg)
1744 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1745 range1beg = PREV_INSN (range1beg);
1747 while (PREV_INSN (range2beg)
1748 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1749 range2beg = PREV_INSN (range2beg);
1751 /* Don't move NOTEs for blocks or loops; shift them
1752 outside the ranges, where they'll stay put. */
1753 range1beg = squeeze_notes (range1beg, range1end);
1754 range2beg = squeeze_notes (range2beg, range2end);
1756 /* Get current surrounds of the 2 ranges. */
1757 range1before = PREV_INSN (range1beg);
1758 range2before = PREV_INSN (range2beg);
1759 range1after = NEXT_INSN (range1end);
1760 range2after = NEXT_INSN (range2end);
1762 /* Splice range2 where range1 was. */
1763 NEXT_INSN (range1before) = range2beg;
1764 PREV_INSN (range2beg) = range1before;
1765 NEXT_INSN (range2end) = range1after;
1766 PREV_INSN (range1after) = range2end;
1767 /* Splice range1 where range2 was. */
1768 NEXT_INSN (range2before) = range1beg;
1769 PREV_INSN (range1beg) = range2before;
1770 NEXT_INSN (range1end) = range2after;
1771 PREV_INSN (range2after) = range1end;
1778 /* Now that the jump has been tensioned,
1779 try cross jumping: check for identical code
1780 before the jump and before its target label. */
1782 /* First, cross jumping of conditional jumps: */
1784 if (cross_jump && condjump_p (insn))
1786 rtx newjpos, newlpos;
1787 rtx x = prev_real_insn (JUMP_LABEL (insn));
1789 /* A conditional jump may be crossjumped
1790 only if the place it jumps to follows
1791 an opposing jump that comes back here. */
1793 if (x != 0 && ! jump_back_p (x, insn))
1794 /* We have no opposing jump;
1795 cannot cross jump this insn. */
1799 /* TARGET is nonzero if it is ok to cross jump
1800 to code before TARGET. If so, see if matches. */
1802 find_cross_jump (insn, x, 2,
1803 &newjpos, &newlpos);
1807 do_cross_jump (insn, newjpos, newlpos);
1808 /* Make the old conditional jump
1809 into an unconditional one. */
1810 SET_SRC (PATTERN (insn))
1811 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
1812 INSN_CODE (insn) = -1;
1813 emit_barrier_after (insn);
1814 /* Add to jump_chain unless this is a new label
1815 whose UID is too large. */
1816 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1818 jump_chain[INSN_UID (insn)]
1819 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1820 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1827 /* Cross jumping of unconditional jumps:
1828 a few differences. */
1830 if (cross_jump && simplejump_p (insn))
1832 rtx newjpos, newlpos;
1837 /* TARGET is nonzero if it is ok to cross jump
1838 to code before TARGET. If so, see if matches. */
1839 find_cross_jump (insn, JUMP_LABEL (insn), 1,
1840 &newjpos, &newlpos);
1842 /* If cannot cross jump to code before the label,
1843 see if we can cross jump to another jump to
1845 /* Try each other jump to this label. */
1846 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
1847 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1848 target != 0 && newjpos == 0;
1849 target = jump_chain[INSN_UID (target)])
1851 && JUMP_LABEL (target) == JUMP_LABEL (insn)
1852 /* Ignore TARGET if it's deleted. */
1853 && ! INSN_DELETED_P (target))
1854 find_cross_jump (insn, target, 2,
1855 &newjpos, &newlpos);
1859 do_cross_jump (insn, newjpos, newlpos);
1865 /* This code was dead in the previous jump.c! */
1866 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
1868 /* Return insns all "jump to the same place"
1869 so we can cross-jump between any two of them. */
1871 rtx newjpos, newlpos, target;
1875 /* If cannot cross jump to code before the label,
1876 see if we can cross jump to another jump to
1878 /* Try each other jump to this label. */
1879 for (target = jump_chain[0];
1880 target != 0 && newjpos == 0;
1881 target = jump_chain[INSN_UID (target)])
1883 && ! INSN_DELETED_P (target)
1884 && GET_CODE (PATTERN (target)) == RETURN)
1885 find_cross_jump (insn, target, 2,
1886 &newjpos, &newlpos);
1890 do_cross_jump (insn, newjpos, newlpos);
1901 /* Delete extraneous line number notes.
1902 Note that two consecutive notes for different lines are not really
1903 extraneous. There should be some indication where that line belonged,
1904 even if it became empty. */
1909 for (insn = f; insn; insn = NEXT_INSN (insn))
1910 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
1912 /* Delete this note if it is identical to previous note. */
1914 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
1915 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
1928 /* If we fall through to the epilogue, see if we can insert a RETURN insn
1929 in front of it. If the machine allows it at this point (we might be
1930 after reload for a leaf routine), it will improve optimization for it
1931 to be there. We do this both here and at the start of this pass since
1932 the RETURN might have been deleted by some of our optimizations. */
1933 insn = get_last_insn ();
1934 while (insn && GET_CODE (insn) == NOTE)
1935 insn = PREV_INSN (insn);
1937 if (insn && GET_CODE (insn) != BARRIER)
1939 emit_jump_insn (gen_return ());
1945 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1946 If so, delete it, and record that this function can drop off the end. */
1952 /* One label can follow the end-note: the return label. */
1953 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
1954 /* Ordinary insns can follow it if returning a structure. */
1955 || GET_CODE (insn) == INSN
1956 /* If machine uses explicit RETURN insns, no epilogue,
1957 then one of them follows the note. */
1958 || (GET_CODE (insn) == JUMP_INSN
1959 && GET_CODE (PATTERN (insn)) == RETURN)
1960 /* Other kinds of notes can follow also. */
1961 || (GET_CODE (insn) == NOTE
1962 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
1963 insn = PREV_INSN (insn);
1966 /* Report if control can fall through at the end of the function. */
1967 if (insn && GET_CODE (insn) == NOTE
1968 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
1974 /* Show JUMP_CHAIN no longer valid. */
1978 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1979 jump. Assume that this unconditional jump is to the exit test code. If
1980 the code is sufficiently simple, make a copy of it before INSN,
1981 followed by a jump to the exit of the loop. Then delete the unconditional
1984 Note that it is possible we can get confused here if the jump immediately
1985 after the loop start branches outside the loop but within an outer loop.
1986 If we are near the exit of that loop, we will copy its exit test. This
1987 will not generate incorrect code, but could suppress some optimizations.
1988 However, such cases are degenerate loops anyway.
1990 Return 1 if we made the change, else 0.
1992 This is only safe immediately after a regscan pass because it uses the
1993 values of regno_first_uid and regno_last_uid. */
1996 duplicate_loop_exit_test (loop_start)
2002 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2004 int max_reg = max_reg_num ();
2007 /* Scan the exit code. We do not perform this optimization if any insn:
2011 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2012 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2013 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2016 Also, don't do this if the exit code is more than 20 insns. */
2018 for (insn = exitcode;
2020 && ! (GET_CODE (insn) == NOTE
2021 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2022 insn = NEXT_INSN (insn))
2024 switch (GET_CODE (insn))
2030 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2031 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2032 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
2037 if (++num_insns > 20
2038 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2039 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2045 /* Unless INSN is zero, we can do the optimization. */
2051 /* See if any insn sets a register only used in the loop exit code and
2052 not a user variable. If so, replace it with a new register. */
2053 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2054 if (GET_CODE (insn) == INSN
2055 && (set = single_set (insn)) != 0
2056 && GET_CODE (SET_DEST (set)) == REG
2057 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
2058 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn))
2060 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2061 if (regno_last_uid[REGNO (SET_DEST (set))] == INSN_UID (p))
2066 /* We can do the replacement. Allocate reg_map if this is the
2067 first replacement we found. */
2070 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2071 bzero (reg_map, max_reg * sizeof (rtx));
2074 REG_LOOP_TEST_P (SET_DEST (set)) = 1;
2076 reg_map[REGNO (SET_DEST (set))]
2077 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
2081 /* Now copy each insn. */
2082 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2083 switch (GET_CODE (insn))
2086 copy = emit_barrier_before (loop_start);
2089 /* Only copy line-number notes. */
2090 if (NOTE_LINE_NUMBER (insn) >= 0)
2092 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2093 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2098 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2100 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2102 mark_jump_label (PATTERN (copy), copy, 0);
2104 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2106 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2107 if (REG_NOTE_KIND (link) != REG_LABEL)
2109 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
2110 XEXP (link, 0), REG_NOTES (copy)));
2111 if (reg_map && REG_NOTES (copy))
2112 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2116 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2118 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2119 mark_jump_label (PATTERN (copy), copy, 0);
2120 if (REG_NOTES (insn))
2122 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2124 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2127 /* If this is a simple jump, add it to the jump chain. */
2129 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2130 && simplejump_p (copy))
2132 jump_chain[INSN_UID (copy)]
2133 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2134 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2142 /* Now clean up by emitting a jump to the end label and deleting the jump
2143 at the start of the loop. */
2144 if (GET_CODE (copy) != BARRIER)
2146 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2148 mark_jump_label (PATTERN (copy), copy, 0);
2149 if (INSN_UID (copy) < max_jump_chain
2150 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2152 jump_chain[INSN_UID (copy)]
2153 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2154 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2156 emit_barrier_before (loop_start);
2159 delete_insn (next_nonnote_insn (loop_start));
2161 /* Mark the exit code as the virtual top of the converted loop. */
2162 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2167 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2168 loop-end notes between START and END out before START. Assume that
2169 END is not such a note. START may be such a note. Returns the value
2170 of the new starting insn, which may be different if the original start
2174 squeeze_notes (start, end)
2180 for (insn = start; insn != end; insn = next)
2182 next = NEXT_INSN (insn);
2183 if (GET_CODE (insn) == NOTE
2184 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2185 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2186 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2187 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2188 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2189 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2195 rtx prev = PREV_INSN (insn);
2196 PREV_INSN (insn) = PREV_INSN (start);
2197 NEXT_INSN (insn) = start;
2198 NEXT_INSN (PREV_INSN (insn)) = insn;
2199 PREV_INSN (NEXT_INSN (insn)) = insn;
2200 NEXT_INSN (prev) = next;
2201 PREV_INSN (next) = prev;
2209 /* Compare the instructions before insn E1 with those before E2
2210 to find an opportunity for cross jumping.
2211 (This means detecting identical sequences of insns followed by
2212 jumps to the same place, or followed by a label and a jump
2213 to that label, and replacing one with a jump to the other.)
2215 Assume E1 is a jump that jumps to label E2
2216 (that is not always true but it might as well be).
2217 Find the longest possible equivalent sequences
2218 and store the first insns of those sequences into *F1 and *F2.
2219 Store zero there if no equivalent preceding instructions are found.
2221 We give up if we find a label in stream 1.
2222 Actually we could transfer that label into stream 2. */
2225 find_cross_jump (e1, e2, minimum, f1, f2)
2230 register rtx i1 = e1, i2 = e2;
2231 register rtx p1, p2;
2234 rtx last1 = 0, last2 = 0;
2235 rtx afterlast1 = 0, afterlast2 = 0;
2243 i1 = prev_nonnote_insn (i1);
2245 i2 = PREV_INSN (i2);
2246 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2247 i2 = PREV_INSN (i2);
2252 /* Don't allow the range of insns preceding E1 or E2
2253 to include the other (E2 or E1). */
2254 if (i2 == e1 || i1 == e2)
2257 /* If we will get to this code by jumping, those jumps will be
2258 tensioned to go directly to the new label (before I2),
2259 so this cross-jumping won't cost extra. So reduce the minimum. */
2260 if (GET_CODE (i1) == CODE_LABEL)
2266 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2273 /* If cross_jump_death_matters is not 0, the insn's mode
2274 indicates whether or not the insn contains any stack-like
2277 if (cross_jump_death_matters && GET_MODE (i1) == QImode)
2279 /* If register stack conversion has already been done, then
2280 death notes must also be compared before it is certain that
2281 the two instruction streams match. */
2284 HARD_REG_SET i1_regset, i2_regset;
2286 CLEAR_HARD_REG_SET (i1_regset);
2287 CLEAR_HARD_REG_SET (i2_regset);
2289 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2290 if (REG_NOTE_KIND (note) == REG_DEAD
2291 && STACK_REG_P (XEXP (note, 0)))
2292 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2294 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2295 if (REG_NOTE_KIND (note) == REG_DEAD
2296 && STACK_REG_P (XEXP (note, 0)))
2297 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2299 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2308 if (lose || GET_CODE (p1) != GET_CODE (p2)
2309 || ! rtx_renumbered_equal_p (p1, p2))
2311 /* The following code helps take care of G++ cleanups. */
2315 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2316 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2317 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2318 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2319 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2320 /* If the equivalences are not to a constant, they may
2321 reference pseudos that no longer exist, so we can't
2323 && CONSTANT_P (XEXP (equiv1, 0))
2324 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2326 rtx s1 = single_set (i1);
2327 rtx s2 = single_set (i2);
2328 if (s1 != 0 && s2 != 0
2329 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2331 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2332 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2333 if (! rtx_renumbered_equal_p (p1, p2))
2335 else if (apply_change_group ())
2340 /* Insns fail to match; cross jumping is limited to the following
2344 /* Don't allow the insn after a compare to be shared by
2345 cross-jumping unless the compare is also shared.
2346 Here, if either of these non-matching insns is a compare,
2347 exclude the following insn from possible cross-jumping. */
2348 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2349 last1 = afterlast1, last2 = afterlast2, ++minimum;
2352 /* If cross-jumping here will feed a jump-around-jump
2353 optimization, this jump won't cost extra, so reduce
2355 if (GET_CODE (i1) == JUMP_INSN
2357 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2363 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2365 /* Ok, this insn is potentially includable in a cross-jump here. */
2366 afterlast1 = last1, afterlast2 = last2;
2367 last1 = i1, last2 = i2, --minimum;
2371 /* We have to be careful that we do not cross-jump into the middle of
2372 USE-CALL_INSN-CLOBBER sequence. This sequence is used instead of
2373 putting the USE and CLOBBERs inside the CALL_INSN. The delay slot
2374 scheduler needs to know what registers are used and modified by the
2375 CALL_INSN and needs the adjacent USE and CLOBBERs to do so.
2377 ??? At some point we should probably change this so that these are
2378 part of the CALL_INSN. The way we are doing it now is a kludge that
2379 is now causing trouble. */
2381 if (last1 != 0 && GET_CODE (last1) == CALL_INSN
2382 && (prev1 = prev_nonnote_insn (last1))
2383 && GET_CODE (prev1) == INSN
2384 && GET_CODE (PATTERN (prev1)) == USE)
2386 /* Remove this CALL_INSN from the range we can cross-jump. */
2387 last1 = next_real_insn (last1);
2388 last2 = next_real_insn (last2);
2393 /* Skip past CLOBBERS since they may be right after a CALL_INSN. It
2394 isn't worth checking for the CALL_INSN. */
2395 while (last1 != 0 && GET_CODE (PATTERN (last1)) == CLOBBER)
2396 last1 = next_real_insn (last1), last2 = next_real_insn (last2);
2398 if (minimum <= 0 && last1 != 0 && last1 != e1)
2399 *f1 = last1, *f2 = last2;
2403 do_cross_jump (insn, newjpos, newlpos)
2404 rtx insn, newjpos, newlpos;
2406 /* Find an existing label at this point
2407 or make a new one if there is none. */
2408 register rtx label = get_label_before (newlpos);
2410 /* Make the same jump insn jump to the new point. */
2411 if (GET_CODE (PATTERN (insn)) == RETURN)
2413 /* Remove from jump chain of returns. */
2414 delete_from_jump_chain (insn);
2415 /* Change the insn. */
2416 PATTERN (insn) = gen_jump (label);
2417 INSN_CODE (insn) = -1;
2418 JUMP_LABEL (insn) = label;
2419 LABEL_NUSES (label)++;
2420 /* Add to new the jump chain. */
2421 if (INSN_UID (label) < max_jump_chain
2422 && INSN_UID (insn) < max_jump_chain)
2424 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2425 jump_chain[INSN_UID (label)] = insn;
2429 redirect_jump (insn, label);
2431 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2432 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2433 the NEWJPOS stream. */
2435 while (newjpos != insn)
2439 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2440 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2441 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2442 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2443 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2444 remove_note (newlpos, lnote);
2446 delete_insn (newjpos);
2447 newjpos = next_real_insn (newjpos);
2448 newlpos = next_real_insn (newlpos);
2452 /* Return the label before INSN, or put a new label there. */
2455 get_label_before (insn)
2460 /* Find an existing label at this point
2461 or make a new one if there is none. */
2462 label = prev_nonnote_insn (insn);
2464 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2466 rtx prev = PREV_INSN (insn);
2468 /* Don't put a label between a CALL_INSN and USE insns that precede
2471 if (GET_CODE (insn) == CALL_INSN
2472 || (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SEQUENCE
2473 && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == CALL_INSN))
2474 while (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == USE)
2475 prev = PREV_INSN (prev);
2477 label = gen_label_rtx ();
2478 emit_label_after (label, prev);
2479 LABEL_NUSES (label) = 0;
2484 /* Return the label after INSN, or put a new label there. */
2487 get_label_after (insn)
2492 /* Find an existing label at this point
2493 or make a new one if there is none. */
2494 label = next_nonnote_insn (insn);
2496 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2498 /* Don't put a label between a CALL_INSN and CLOBBER insns
2501 if (GET_CODE (insn) == CALL_INSN
2502 || (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SEQUENCE
2503 && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == CALL_INSN))
2504 while (GET_CODE (NEXT_INSN (insn)) == INSN
2505 && GET_CODE (PATTERN (NEXT_INSN (insn))) == CLOBBER)
2506 insn = NEXT_INSN (insn);
2508 label = gen_label_rtx ();
2509 emit_label_after (label, insn);
2510 LABEL_NUSES (label) = 0;
2515 /* Return 1 if INSN is a jump that jumps to right after TARGET
2516 only on the condition that TARGET itself would drop through.
2517 Assumes that TARGET is a conditional jump. */
2520 jump_back_p (insn, target)
2524 enum rtx_code codei, codet;
2526 if (simplejump_p (insn) || ! condjump_p (insn)
2527 || simplejump_p (target)
2528 || target != prev_real_insn (JUMP_LABEL (insn)))
2531 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2532 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2534 codei = GET_CODE (cinsn);
2535 codet = GET_CODE (ctarget);
2537 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2539 if (! can_reverse_comparison_p (cinsn, insn))
2541 codei = reverse_condition (codei);
2544 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2546 if (! can_reverse_comparison_p (ctarget, target))
2548 codet = reverse_condition (codet);
2551 return (codei == codet
2552 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2553 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2556 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2557 return non-zero if it is safe to reverse this comparison. It is if our
2558 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2559 this is known to be an integer comparison. */
2562 can_reverse_comparison_p (comparison, insn)
2568 /* If this is not actually a comparison, we can't reverse it. */
2569 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2572 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2573 /* If this is an NE comparison, it is safe to reverse it to an EQ
2574 comparison and vice versa, even for floating point. If no operands
2575 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2576 always false and NE is always true, so the reversal is also valid. */
2578 || GET_CODE (comparison) == NE
2579 || GET_CODE (comparison) == EQ)
2582 arg0 = XEXP (comparison, 0);
2584 /* Make sure ARG0 is one of the actual objects being compared. If we
2585 can't do this, we can't be sure the comparison can be reversed.
2587 Handle cc0 and a MODE_CC register. */
2588 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2594 rtx prev = prev_nonnote_insn (insn);
2595 rtx set = single_set (prev);
2597 if (set == 0 || SET_DEST (set) != arg0)
2600 arg0 = SET_SRC (set);
2602 if (GET_CODE (arg0) == COMPARE)
2603 arg0 = XEXP (arg0, 0);
2606 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2607 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2608 return (GET_CODE (arg0) == CONST_INT
2609 || (GET_MODE (arg0) != VOIDmode
2610 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2611 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2614 /* Given an rtx-code for a comparison, return the code
2615 for the negated comparison.
2616 WATCH OUT! reverse_condition is not safe to use on a jump
2617 that might be acting on the results of an IEEE floating point comparison,
2618 because of the special treatment of non-signaling nans in comparisons.
2619 Use can_reverse_comparison_p to be sure. */
2622 reverse_condition (code)
2663 /* Similar, but return the code when two operands of a comparison are swapped.
2664 This IS safe for IEEE floating-point. */
2667 swap_condition (code)
2706 /* Given a comparison CODE, return the corresponding unsigned comparison.
2707 If CODE is an equality comparison or already an unsigned comparison,
2708 CODE is returned. */
2711 unsigned_condition (code)
2741 /* Similarly, return the signed version of a comparison. */
2744 signed_condition (code)
2774 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2775 truth of CODE1 implies the truth of CODE2. */
2778 comparison_dominates_p (code1, code2)
2779 enum rtx_code code1, code2;
2787 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
2792 if (code2 == LE || code2 == NE)
2797 if (code2 == GE || code2 == NE)
2802 if (code2 == LEU || code2 == NE)
2807 if (code2 == GEU || code2 == NE)
2815 /* Return 1 if INSN is an unconditional jump and nothing else. */
2821 return (GET_CODE (insn) == JUMP_INSN
2822 && GET_CODE (PATTERN (insn)) == SET
2823 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2824 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2827 /* Return nonzero if INSN is a (possibly) conditional jump
2828 and nothing more. */
2834 register rtx x = PATTERN (insn);
2835 if (GET_CODE (x) != SET)
2837 if (GET_CODE (SET_DEST (x)) != PC)
2839 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2841 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2843 if (XEXP (SET_SRC (x), 2) == pc_rtx
2844 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2845 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2847 if (XEXP (SET_SRC (x), 1) == pc_rtx
2848 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2849 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2854 /* Return 1 if X is an RTX that does nothing but set the condition codes
2855 and CLOBBER or USE registers.
2856 Return -1 if X does explicitly set the condition codes,
2857 but also does other things. */
2864 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2866 if (GET_CODE (x) == PARALLEL)
2870 int other_things = 0;
2871 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2873 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2874 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2876 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2879 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2887 /* Follow any unconditional jump at LABEL;
2888 return the ultimate label reached by any such chain of jumps.
2889 If LABEL is not followed by a jump, return LABEL.
2890 If the chain loops or we can't find end, return LABEL,
2891 since that tells caller to avoid changing the insn.
2893 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2894 a USE or CLOBBER. */
2897 follow_jumps (label)
2902 register rtx value = label;
2907 && (insn = next_active_insn (value)) != 0
2908 && GET_CODE (insn) == JUMP_INSN
2909 && (JUMP_LABEL (insn) != 0 || GET_CODE (PATTERN (insn)) == RETURN)
2910 && (next = NEXT_INSN (insn))
2911 && GET_CODE (next) == BARRIER);
2914 /* Don't chain through the insn that jumps into a loop
2915 from outside the loop,
2916 since that would create multiple loop entry jumps
2917 and prevent loop optimization. */
2919 if (!reload_completed)
2920 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2921 if (GET_CODE (tem) == NOTE
2922 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
2925 /* If we have found a cycle, make the insn jump to itself. */
2926 if (JUMP_LABEL (insn) == label)
2929 tem = next_active_insn (JUMP_LABEL (insn));
2930 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
2931 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
2934 value = JUMP_LABEL (insn);
2941 /* Assuming that field IDX of X is a vector of label_refs,
2942 replace each of them by the ultimate label reached by it.
2943 Return nonzero if a change is made.
2944 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2947 tension_vector_labels (x, idx)
2953 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2955 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2956 register rtx nlabel = follow_jumps (olabel);
2957 if (nlabel && nlabel != olabel)
2959 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2960 ++LABEL_NUSES (nlabel);
2961 if (--LABEL_NUSES (olabel) == 0)
2962 delete_insn (olabel);
2969 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2970 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2971 in INSN, then store one of them in JUMP_LABEL (INSN).
2972 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2973 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2974 Also, when there are consecutive labels, canonicalize on the last of them.
2976 Note that two labels separated by a loop-beginning note
2977 must be kept distinct if we have not yet done loop-optimization,
2978 because the gap between them is where loop-optimize
2979 will want to move invariant code to. CROSS_JUMP tells us
2980 that loop-optimization is done with.
2982 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2983 two labels distinct if they are separated by only USE or CLOBBER insns. */
2986 mark_jump_label (x, insn, cross_jump)
2991 register RTX_CODE code = GET_CODE (x);
3009 /* If this is a constant-pool reference, see if it is a label. */
3010 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3011 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3012 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3017 register rtx label = XEXP (x, 0);
3019 if (GET_CODE (label) != CODE_LABEL)
3021 /* Ignore references to labels of containing functions. */
3022 if (LABEL_REF_NONLOCAL_P (x))
3024 /* If there are other labels following this one,
3025 replace it with the last of the consecutive labels. */
3026 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3028 if (GET_CODE (next) == CODE_LABEL)
3030 else if (cross_jump && GET_CODE (next) == INSN
3031 && (GET_CODE (PATTERN (next)) == USE
3032 || GET_CODE (PATTERN (next)) == CLOBBER))
3034 else if (GET_CODE (next) != NOTE)
3036 else if (! cross_jump
3037 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3038 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
3041 XEXP (x, 0) = label;
3042 ++LABEL_NUSES (label);
3045 if (GET_CODE (insn) == JUMP_INSN)
3046 JUMP_LABEL (insn) = label;
3047 else if (! find_reg_note (insn, REG_LABEL, label))
3049 rtx next = next_real_insn (label);
3050 /* Don't record labels that refer to dispatch tables.
3051 This is not necessary, since the tablejump
3052 references the same label.
3053 And if we did record them, flow.c would make worse code. */
3055 || ! (GET_CODE (next) == JUMP_INSN
3056 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3057 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
3059 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
3061 /* Record in the note whether label is nonlocal. */
3062 LABEL_REF_NONLOCAL_P (REG_NOTES (insn))
3063 = LABEL_REF_NONLOCAL_P (x);
3070 /* Do walk the labels in a vector, but not the first operand of an
3071 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3075 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3077 for (i = 0; i < XVECLEN (x, eltnum); i++)
3078 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3083 fmt = GET_RTX_FORMAT (code);
3084 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3087 mark_jump_label (XEXP (x, i), insn, cross_jump);
3088 else if (fmt[i] == 'E')
3091 for (j = 0; j < XVECLEN (x, i); j++)
3092 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3097 /* If all INSN does is set the pc, delete it,
3098 and delete the insn that set the condition codes for it
3099 if that's what the previous thing was. */
3105 register rtx set = single_set (insn);
3107 if (set && GET_CODE (SET_DEST (set)) == PC)
3108 delete_computation (insn);
3111 /* Delete INSN and recursively delete insns that compute values used only
3112 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3113 If we are running before flow.c, we need do nothing since flow.c will
3114 delete dead code. We also can't know if the registers being used are
3115 dead or not at this point.
3117 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3118 nothing other than set a register that dies in this insn, we can delete
3121 On machines with CC0, if CC0 is used in this insn, we may be able to
3122 delete the insn that set it. */
3125 delete_computation (insn)
3131 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3133 rtx prev = prev_nonnote_insn (insn);
3134 /* We assume that at this stage
3135 CC's are always set explicitly
3136 and always immediately before the jump that
3137 will use them. So if the previous insn
3138 exists to set the CC's, delete it
3139 (unless it performs auto-increments, etc.). */
3140 if (prev && GET_CODE (prev) == INSN
3141 && sets_cc0_p (PATTERN (prev)))
3143 if (sets_cc0_p (PATTERN (prev)) > 0
3144 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3145 delete_computation (prev);
3147 /* Otherwise, show that cc0 won't be used. */
3148 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
3149 cc0_rtx, REG_NOTES (prev));
3154 for (note = REG_NOTES (insn); note; note = next)
3158 next = XEXP (note, 1);
3160 if (REG_NOTE_KIND (note) != REG_DEAD
3161 /* Verify that the REG_NOTE is legitimate. */
3162 || GET_CODE (XEXP (note, 0)) != REG)
3165 for (our_prev = prev_nonnote_insn (insn);
3166 our_prev && GET_CODE (our_prev) == INSN;
3167 our_prev = prev_nonnote_insn (our_prev))
3169 /* If we reach a SEQUENCE, it is too complex to try to
3170 do anything with it, so give up. */
3171 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3174 if (GET_CODE (PATTERN (our_prev)) == USE
3175 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3176 /* reorg creates USEs that look like this. We leave them
3177 alone because reorg needs them for its own purposes. */
3180 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3182 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3185 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3187 /* If we find a SET of something else, we can't
3192 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3194 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3196 if (GET_CODE (part) == SET
3197 && SET_DEST (part) != XEXP (note, 0))
3201 if (i == XVECLEN (PATTERN (our_prev), 0))
3202 delete_computation (our_prev);
3204 else if (GET_CODE (PATTERN (our_prev)) == SET
3205 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3206 delete_computation (our_prev);
3211 /* If OUR_PREV references the register that dies here, it is an
3212 additional use. Hence any prior SET isn't dead. However, this
3213 insn becomes the new place for the REG_DEAD note. */
3214 if (reg_overlap_mentioned_p (XEXP (note, 0),
3215 PATTERN (our_prev)))
3217 XEXP (note, 1) = REG_NOTES (our_prev);
3218 REG_NOTES (our_prev) = note;
3227 /* Delete insn INSN from the chain of insns and update label ref counts.
3228 May delete some following insns as a consequence; may even delete
3229 a label elsewhere and insns that follow it.
3231 Returns the first insn after INSN that was not deleted. */
3237 register rtx next = NEXT_INSN (insn);
3238 register rtx prev = PREV_INSN (insn);
3239 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3240 register int dont_really_delete = 0;
3242 while (next && INSN_DELETED_P (next))
3243 next = NEXT_INSN (next);
3245 /* This insn is already deleted => return first following nondeleted. */
3246 if (INSN_DELETED_P (insn))
3249 /* Don't delete user-declared labels. Convert them to special NOTEs
3251 if (was_code_label && LABEL_NAME (insn) != 0
3252 && optimize && ! dont_really_delete)
3254 PUT_CODE (insn, NOTE);
3255 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3256 NOTE_SOURCE_FILE (insn) = 0;
3257 dont_really_delete = 1;
3260 /* Mark this insn as deleted. */
3261 INSN_DELETED_P (insn) = 1;
3263 /* If this is an unconditional jump, delete it from the jump chain. */
3264 if (simplejump_p (insn))
3265 delete_from_jump_chain (insn);
3267 /* If instruction is followed by a barrier,
3268 delete the barrier too. */
3270 if (next != 0 && GET_CODE (next) == BARRIER)
3272 INSN_DELETED_P (next) = 1;
3273 next = NEXT_INSN (next);
3276 /* Patch out INSN (and the barrier if any) */
3278 if (optimize && ! dont_really_delete)
3282 NEXT_INSN (prev) = next;
3283 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3284 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3285 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3290 PREV_INSN (next) = prev;
3291 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3292 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3295 if (prev && NEXT_INSN (prev) == 0)
3296 set_last_insn (prev);
3299 /* If deleting a jump, decrement the count of the label,
3300 and delete the label if it is now unused. */
3302 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3303 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3305 /* This can delete NEXT or PREV,
3306 either directly if NEXT is JUMP_LABEL (INSN),
3307 or indirectly through more levels of jumps. */
3308 delete_insn (JUMP_LABEL (insn));
3309 /* I feel a little doubtful about this loop,
3310 but I see no clean and sure alternative way
3311 to find the first insn after INSN that is not now deleted.
3312 I hope this works. */
3313 while (next && INSN_DELETED_P (next))
3314 next = NEXT_INSN (next);
3318 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3319 prev = PREV_INSN (prev);
3321 /* If INSN was a label and a dispatch table follows it,
3322 delete the dispatch table. The tablejump must have gone already.
3323 It isn't useful to fall through into a table. */
3326 && NEXT_INSN (insn) != 0
3327 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3328 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3329 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3330 next = delete_insn (NEXT_INSN (insn));
3332 /* If INSN was a label, delete insns following it if now unreachable. */
3334 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3336 register RTX_CODE code;
3338 && ((code = GET_CODE (next)) == INSN
3339 || code == JUMP_INSN || code == CALL_INSN
3341 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3344 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3345 next = NEXT_INSN (next);
3346 /* Keep going past other deleted labels to delete what follows. */
3347 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3348 next = NEXT_INSN (next);
3350 /* Note: if this deletes a jump, it can cause more
3351 deletion of unreachable code, after a different label.
3352 As long as the value from this recursive call is correct,
3353 this invocation functions correctly. */
3354 next = delete_insn (next);
3361 /* Advance from INSN till reaching something not deleted
3362 then return that. May return INSN itself. */
3365 next_nondeleted_insn (insn)
3368 while (INSN_DELETED_P (insn))
3369 insn = NEXT_INSN (insn);
3373 /* Delete a range of insns from FROM to TO, inclusive.
3374 This is for the sake of peephole optimization, so assume
3375 that whatever these insns do will still be done by a new
3376 peephole insn that will replace them. */
3379 delete_for_peephole (from, to)
3380 register rtx from, to;
3382 register rtx insn = from;
3386 register rtx next = NEXT_INSN (insn);
3387 register rtx prev = PREV_INSN (insn);
3389 if (GET_CODE (insn) != NOTE)
3391 INSN_DELETED_P (insn) = 1;
3393 /* Patch this insn out of the chain. */
3394 /* We don't do this all at once, because we
3395 must preserve all NOTEs. */
3397 NEXT_INSN (prev) = next;
3400 PREV_INSN (next) = prev;
3408 /* Note that if TO is an unconditional jump
3409 we *do not* delete the BARRIER that follows,
3410 since the peephole that replaces this sequence
3411 is also an unconditional jump in that case. */
3414 /* Invert the condition of the jump JUMP, and make it jump
3415 to label NLABEL instead of where it jumps now. */
3418 invert_jump (jump, nlabel)
3421 register rtx olabel = JUMP_LABEL (jump);
3423 /* We have to either invert the condition and change the label or
3424 do neither. Either operation could fail. We first try to invert
3425 the jump. If that succeeds, we try changing the label. If that fails,
3426 we invert the jump back to what it was. */
3428 if (! invert_exp (PATTERN (jump), jump))
3431 if (redirect_jump (jump, nlabel))
3434 if (! invert_exp (PATTERN (jump), jump))
3435 /* This should just be putting it back the way it was. */
3441 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3443 Return 1 if we can do so, 0 if we cannot find a way to do so that
3444 matches a pattern. */
3447 invert_exp (x, insn)
3451 register RTX_CODE code;
3455 code = GET_CODE (x);
3457 if (code == IF_THEN_ELSE)
3459 register rtx comp = XEXP (x, 0);
3462 /* We can do this in two ways: The preferable way, which can only
3463 be done if this is not an integer comparison, is to reverse
3464 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3465 of the IF_THEN_ELSE. If we can't do either, fail. */
3467 if (can_reverse_comparison_p (comp, insn)
3468 && validate_change (insn, &XEXP (x, 0),
3469 gen_rtx (reverse_condition (GET_CODE (comp)),
3470 GET_MODE (comp), XEXP (comp, 0),
3471 XEXP (comp, 1)), 0))
3475 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3476 validate_change (insn, &XEXP (x, 2), tem, 1);
3477 return apply_change_group ();
3480 fmt = GET_RTX_FORMAT (code);
3481 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3484 if (! invert_exp (XEXP (x, i), insn))
3489 for (j = 0; j < XVECLEN (x, i); j++)
3490 if (!invert_exp (XVECEXP (x, i, j), insn))
3498 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3499 If the old jump target label is unused as a result,
3500 it and the code following it may be deleted.
3502 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3505 The return value will be 1 if the change was made, 0 if it wasn't (this
3506 can only occur for NLABEL == 0). */
3509 redirect_jump (jump, nlabel)
3512 register rtx olabel = JUMP_LABEL (jump);
3514 if (nlabel == olabel)
3517 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3520 /* If this is an unconditional branch, delete it from the jump_chain of
3521 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3522 have UID's in range and JUMP_CHAIN is valid). */
3523 if (jump_chain && (simplejump_p (jump)
3524 || GET_CODE (PATTERN (jump)) == RETURN))
3526 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3528 delete_from_jump_chain (jump);
3529 if (label_index < max_jump_chain
3530 && INSN_UID (jump) < max_jump_chain)
3532 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3533 jump_chain[label_index] = jump;
3537 JUMP_LABEL (jump) = nlabel;
3539 ++LABEL_NUSES (nlabel);
3541 if (olabel && --LABEL_NUSES (olabel) == 0)
3542 delete_insn (olabel);
3547 /* Delete the instruction JUMP from any jump chain it might be on. */
3550 delete_from_jump_chain (jump)
3554 rtx olabel = JUMP_LABEL (jump);
3556 /* Handle unconditional jumps. */
3557 if (jump_chain && olabel != 0
3558 && INSN_UID (olabel) < max_jump_chain
3559 && simplejump_p (jump))
3560 index = INSN_UID (olabel);
3561 /* Handle return insns. */
3562 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3566 if (jump_chain[index] == jump)
3567 jump_chain[index] = jump_chain[INSN_UID (jump)];
3572 for (insn = jump_chain[index];
3574 insn = jump_chain[INSN_UID (insn)])
3575 if (jump_chain[INSN_UID (insn)] == jump)
3577 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3583 /* If NLABEL is nonzero, throughout the rtx at LOC,
3584 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3585 zero, alter (RETURN) to (LABEL_REF NLABEL).
3587 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3588 validity with validate_change. Convert (set (pc) (label_ref olabel))
3591 Return 0 if we found a change we would like to make but it is invalid.
3592 Otherwise, return 1. */
3595 redirect_exp (loc, olabel, nlabel, insn)
3600 register rtx x = *loc;
3601 register RTX_CODE code = GET_CODE (x);
3605 if (code == LABEL_REF)
3607 if (XEXP (x, 0) == olabel)
3610 XEXP (x, 0) = nlabel;
3612 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3616 else if (code == RETURN && olabel == 0)
3618 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3619 if (loc == &PATTERN (insn))
3620 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3621 return validate_change (insn, loc, x, 0);
3624 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3625 && GET_CODE (SET_SRC (x)) == LABEL_REF
3626 && XEXP (SET_SRC (x), 0) == olabel)
3627 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3629 fmt = GET_RTX_FORMAT (code);
3630 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3633 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3638 for (j = 0; j < XVECLEN (x, i); j++)
3639 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3647 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3649 If the old jump target label (before the dispatch table) becomes unused,
3650 it and the dispatch table may be deleted. In that case, find the insn
3651 before the jump references that label and delete it and logical successors
3655 redirect_tablejump (jump, nlabel)
3658 register rtx olabel = JUMP_LABEL (jump);
3660 /* Add this jump to the jump_chain of NLABEL. */
3661 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3662 && INSN_UID (jump) < max_jump_chain)
3664 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3665 jump_chain[INSN_UID (nlabel)] = jump;
3668 PATTERN (jump) = gen_jump (nlabel);
3669 JUMP_LABEL (jump) = nlabel;
3670 ++LABEL_NUSES (nlabel);
3671 INSN_CODE (jump) = -1;
3673 if (--LABEL_NUSES (olabel) == 0)
3675 delete_labelref_insn (jump, olabel, 0);
3676 delete_insn (olabel);
3680 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3681 If we found one, delete it and then delete this insn if DELETE_THIS is
3682 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3685 delete_labelref_insn (insn, label, delete_this)
3692 if (GET_CODE (insn) != NOTE
3693 && reg_mentioned_p (label, PATTERN (insn)))
3704 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3705 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3719 /* Like rtx_equal_p except that it considers two REGs as equal
3720 if they renumber to the same value. */
3723 rtx_renumbered_equal_p (x, y)
3727 register RTX_CODE code = GET_CODE (x);
3732 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3733 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3734 && GET_CODE (SUBREG_REG (y)) == REG)))
3738 if (GET_MODE (x) != GET_MODE (y))
3741 /* If we haven't done any renumbering, don't
3742 make any assumptions. */
3743 if (reg_renumber == 0)
3744 return rtx_equal_p (x, y);
3748 i = REGNO (SUBREG_REG (x));
3749 if (reg_renumber[i] >= 0)
3750 i = reg_renumber[i];
3751 i += SUBREG_WORD (x);
3756 if (reg_renumber[i] >= 0)
3757 i = reg_renumber[i];
3759 if (GET_CODE (y) == SUBREG)
3761 j = REGNO (SUBREG_REG (y));
3762 if (reg_renumber[j] >= 0)
3763 j = reg_renumber[j];
3764 j += SUBREG_WORD (y);
3769 if (reg_renumber[j] >= 0)
3770 j = reg_renumber[j];
3774 /* Now we have disposed of all the cases
3775 in which different rtx codes can match. */
3776 if (code != GET_CODE (y))
3787 return INTVAL (x) == INTVAL (y);
3790 /* We can't assume nonlocal labels have their following insns yet. */
3791 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3792 return XEXP (x, 0) == XEXP (y, 0);
3793 /* Two label-refs are equivalent if they point at labels
3794 in the same position in the instruction stream. */
3795 return (next_real_insn (XEXP (x, 0))
3796 == next_real_insn (XEXP (y, 0)));
3799 return XSTR (x, 0) == XSTR (y, 0);
3802 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3804 if (GET_MODE (x) != GET_MODE (y))
3807 /* Compare the elements. If any pair of corresponding elements
3808 fail to match, return 0 for the whole things. */
3810 fmt = GET_RTX_FORMAT (code);
3811 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3817 if (XWINT (x, i) != XWINT (y, i))
3822 if (XINT (x, i) != XINT (y, i))
3827 if (strcmp (XSTR (x, i), XSTR (y, i)))
3832 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3837 if (XEXP (x, i) != XEXP (y, i))
3844 if (XVECLEN (x, i) != XVECLEN (y, i))
3846 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3847 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3858 /* If X is a hard register or equivalent to one or a subregister of one,
3859 return the hard register number. If X is a pseudo register that was not
3860 assigned a hard register, return the pseudo register number. Otherwise,
3861 return -1. Any rtx is valid for X. */
3867 if (GET_CODE (x) == REG)
3869 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3870 return reg_renumber[REGNO (x)];
3873 if (GET_CODE (x) == SUBREG)
3875 int base = true_regnum (SUBREG_REG (x));
3876 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3877 return SUBREG_WORD (x) + base;
3882 /* Optimize code of the form:
3884 for (x = a[i]; x; ...)
3886 for (x = a[i]; x; ...)
3890 Loop optimize will change the above code into
3894 { ...; if (! (x = ...)) break; }
3897 { ...; if (! (x = ...)) break; }
3900 In general, if the first test fails, the program can branch
3901 directly to `foo' and skip the second try which is doomed to fail.
3902 We run this after loop optimization and before flow analysis. */
3904 /* When comparing the insn patterns, we track the fact that different
3905 pseudo-register numbers may have been used in each computation.
3906 The following array stores an equivalence -- same_regs[I] == J means
3907 that pseudo register I was used in the first set of tests in a context
3908 where J was used in the second set. We also count the number of such
3909 pending equivalences. If nonzero, the expressions really aren't the
3912 static int *same_regs;
3914 static int num_same_regs;
3916 /* Track any registers modified between the target of the first jump and
3917 the second jump. They never compare equal. */
3919 static char *modified_regs;
3921 /* Record if memory was modified. */
3923 static int modified_mem;
3925 /* Called via note_stores on each insn between the target of the first
3926 branch and the second branch. It marks any changed registers. */
3929 mark_modified_reg (dest, x)
3935 if (GET_CODE (dest) == SUBREG)
3936 dest = SUBREG_REG (dest);
3938 if (GET_CODE (dest) == MEM)
3941 if (GET_CODE (dest) != REG)
3944 regno = REGNO (dest);
3945 if (regno >= FIRST_PSEUDO_REGISTER)
3946 modified_regs[regno] = 1;
3948 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3949 modified_regs[regno + i] = 1;
3952 /* F is the first insn in the chain of insns. */
3955 thread_jumps (f, max_reg, flag_before_loop)
3958 int flag_before_loop;
3960 /* Basic algorithm is to find a conditional branch,
3961 the label it may branch to, and the branch after
3962 that label. If the two branches test the same condition,
3963 walk back from both branch paths until the insn patterns
3964 differ, or code labels are hit. If we make it back to
3965 the target of the first branch, then we know that the first branch
3966 will either always succeed or always fail depending on the relative
3967 senses of the two branches. So adjust the first branch accordingly
3970 rtx label, b1, b2, t1, t2;
3971 enum rtx_code code1, code2;
3972 rtx b1op0, b1op1, b2op0, b2op1;
3977 /* Allocate register tables and quick-reset table. */
3978 modified_regs = (char *) alloca (max_reg * sizeof (char));
3979 same_regs = (int *) alloca (max_reg * sizeof (int));
3980 all_reset = (int *) alloca (max_reg * sizeof (int));
3981 for (i = 0; i < max_reg; i++)
3988 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3990 /* Get to a candidate branch insn. */
3991 if (GET_CODE (b1) != JUMP_INSN
3992 || ! condjump_p (b1) || simplejump_p (b1)
3993 || JUMP_LABEL (b1) == 0)
3996 bzero (modified_regs, max_reg * sizeof (char));
3999 bcopy (all_reset, same_regs, max_reg * sizeof (int));
4002 label = JUMP_LABEL (b1);
4004 /* Look for a branch after the target. Record any registers and
4005 memory modified between the target and the branch. Stop when we
4006 get to a label since we can't know what was changed there. */
4007 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4009 if (GET_CODE (b2) == CODE_LABEL)
4012 else if (GET_CODE (b2) == JUMP_INSN)
4014 /* If this is an unconditional jump and is the only use of
4015 its target label, we can follow it. */
4016 if (simplejump_p (b2)
4017 && JUMP_LABEL (b2) != 0
4018 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4020 b2 = JUMP_LABEL (b2);
4027 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4030 if (GET_CODE (b2) == CALL_INSN)
4033 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4034 if (call_used_regs[i] && ! fixed_regs[i]
4035 && i != STACK_POINTER_REGNUM
4036 && i != FRAME_POINTER_REGNUM
4037 && i != HARD_FRAME_POINTER_REGNUM
4038 && i != ARG_POINTER_REGNUM)
4039 modified_regs[i] = 1;
4042 note_stores (PATTERN (b2), mark_modified_reg);
4045 /* Check the next candidate branch insn from the label
4048 || GET_CODE (b2) != JUMP_INSN
4050 || ! condjump_p (b2)
4051 || simplejump_p (b2))
4054 /* Get the comparison codes and operands, reversing the
4055 codes if appropriate. If we don't have comparison codes,
4056 we can't do anything. */
4057 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4058 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4059 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4060 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4061 code1 = reverse_condition (code1);
4063 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4064 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4065 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4066 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4067 code2 = reverse_condition (code2);
4069 /* If they test the same things and knowing that B1 branches
4070 tells us whether or not B2 branches, check if we
4071 can thread the branch. */
4072 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4073 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4074 && (comparison_dominates_p (code1, code2)
4075 || comparison_dominates_p (code1, reverse_condition (code2))))
4077 t1 = prev_nonnote_insn (b1);
4078 t2 = prev_nonnote_insn (b2);
4080 while (t1 != 0 && t2 != 0)
4084 /* We have reached the target of the first branch.
4085 If there are no pending register equivalents,
4086 we know that this branch will either always
4087 succeed (if the senses of the two branches are
4088 the same) or always fail (if not). */
4091 if (num_same_regs != 0)
4094 if (comparison_dominates_p (code1, code2))
4095 new_label = JUMP_LABEL (b2);
4097 new_label = get_label_after (b2);
4099 if (JUMP_LABEL (b1) != new_label)
4101 rtx prev = PREV_INSN (new_label);
4103 if (flag_before_loop
4104 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4106 /* Don't thread to the loop label. If a loop
4107 label is reused, loop optimization will
4108 be disabled for that loop. */
4109 new_label = gen_label_rtx ();
4110 emit_label_after (new_label, PREV_INSN (prev));
4112 changed |= redirect_jump (b1, new_label);
4117 /* If either of these is not a normal insn (it might be
4118 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4119 have already been skipped above.) Similarly, fail
4120 if the insns are different. */
4121 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4122 || recog_memoized (t1) != recog_memoized (t2)
4123 || ! rtx_equal_for_thread_p (PATTERN (t1),
4127 t1 = prev_nonnote_insn (t1);
4128 t2 = prev_nonnote_insn (t2);
4135 /* This is like RTX_EQUAL_P except that it knows about our handling of
4136 possibly equivalent registers and knows to consider volatile and
4137 modified objects as not equal.
4139 YINSN is the insn containing Y. */
4142 rtx_equal_for_thread_p (x, y, yinsn)
4148 register enum rtx_code code;
4151 code = GET_CODE (x);
4152 /* Rtx's of different codes cannot be equal. */
4153 if (code != GET_CODE (y))
4156 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4157 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4159 if (GET_MODE (x) != GET_MODE (y))
4162 /* Handle special-cases first. */
4166 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4169 /* If neither is user variable or hard register, check for possible
4171 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4172 || REGNO (x) < FIRST_PSEUDO_REGISTER
4173 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4176 if (same_regs[REGNO (x)] == -1)
4178 same_regs[REGNO (x)] = REGNO (y);
4181 /* If this is the first time we are seeing a register on the `Y'
4182 side, see if it is the last use. If not, we can't thread the
4183 jump, so mark it as not equivalent. */
4184 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
4190 return (same_regs[REGNO (x)] == REGNO (y));
4195 /* If memory modified or either volatile, not equivalent.
4196 Else, check address. */
4197 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4200 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4203 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4209 /* Cancel a pending `same_regs' if setting equivalenced registers.
4210 Then process source. */
4211 if (GET_CODE (SET_DEST (x)) == REG
4212 && GET_CODE (SET_DEST (y)) == REG)
4214 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4216 same_regs[REGNO (SET_DEST (x))] = -1;
4219 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4223 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4226 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4229 return XEXP (x, 0) == XEXP (y, 0);
4232 return XSTR (x, 0) == XSTR (y, 0);
4238 fmt = GET_RTX_FORMAT (code);
4239 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4244 if (XWINT (x, i) != XWINT (y, i))
4250 if (XINT (x, i) != XINT (y, i))
4256 /* Two vectors must have the same length. */
4257 if (XVECLEN (x, i) != XVECLEN (y, i))
4260 /* And the corresponding elements must match. */
4261 for (j = 0; j < XVECLEN (x, i); j++)
4262 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4263 XVECEXP (y, i, j), yinsn) == 0)
4268 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4274 if (strcmp (XSTR (x, i), XSTR (y, i)))
4279 /* These are just backpointers, so they don't matter. */
4285 /* It is believed that rtx's at this level will never
4286 contain anything but integers and other rtx's,
4287 except for within LABEL_REFs and SYMBOL_REFs. */