1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992 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)
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 register rtx 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 (SET_DEST (pbody))
350 > stack_adjust_amount)
352 total_pushed += GET_MODE_SIZE (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 (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 /* Now iterate optimizing jumps until nothing changes over one pass. */
535 for (insn = f; insn; insn = next)
538 rtx temp, temp1, temp2, temp3, temp4, temp5;
540 int this_is_simplejump, this_is_condjump, reversep;
542 /* If NOT the first iteration, if this is the last jump pass
543 (just before final), do the special peephole optimizations.
544 Avoiding the first iteration gives ordinary jump opts
545 a chance to work before peephole opts. */
547 if (reload_completed && !first && !flag_no_peephole)
548 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
552 /* That could have deleted some insns after INSN, so check now
553 what the following insn is. */
555 next = NEXT_INSN (insn);
557 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
558 jump. Try to optimize by duplicating the loop exit test if so.
559 This is only safe immediately after regscan, because it uses
560 the values of regno_first_uid and regno_last_uid. */
561 if (after_regscan && GET_CODE (insn) == NOTE
562 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
563 && (temp1 = next_nonnote_insn (insn)) != 0
564 && simplejump_p (temp1))
566 temp = PREV_INSN (insn);
567 if (duplicate_loop_exit_test (insn))
570 next = NEXT_INSN (temp);
575 if (GET_CODE (insn) != JUMP_INSN)
578 this_is_simplejump = simplejump_p (insn);
579 this_is_condjump = condjump_p (insn);
581 /* Tension the labels in dispatch tables. */
583 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
584 changed |= tension_vector_labels (PATTERN (insn), 0);
585 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
586 changed |= tension_vector_labels (PATTERN (insn), 1);
588 /* If a dispatch table always goes to the same place,
589 get rid of it and replace the insn that uses it. */
591 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
592 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
595 rtx pat = PATTERN (insn);
596 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
597 int len = XVECLEN (pat, diff_vec_p);
598 rtx dispatch = prev_real_insn (insn);
600 for (i = 0; i < len; i++)
601 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
602 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
605 && GET_CODE (dispatch) == JUMP_INSN
606 && JUMP_LABEL (dispatch) != 0
607 /* Don't mess with a casesi insn. */
608 && !(GET_CODE (PATTERN (dispatch)) == SET
609 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
611 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
613 redirect_tablejump (dispatch,
614 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
619 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
621 /* If a jump references the end of the function, try to turn
622 it into a RETURN insn, possibly a conditional one. */
623 if (JUMP_LABEL (insn)
624 && next_active_insn (JUMP_LABEL (insn)) == 0)
625 changed |= redirect_jump (insn, NULL_RTX);
627 /* Detect jump to following insn. */
628 if (reallabelprev == insn && condjump_p (insn))
635 /* If we have an unconditional jump preceded by a USE, try to put
636 the USE before the target and jump there. This simplifies many
637 of the optimizations below since we don't have to worry about
638 dealing with these USE insns. We only do this if the label
639 being branch to already has the identical USE or if code
640 never falls through to that label. */
642 if (this_is_simplejump
643 && (temp = prev_nonnote_insn (insn)) != 0
644 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
645 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
646 && (GET_CODE (temp1) == BARRIER
647 || (GET_CODE (temp1) == INSN
648 && rtx_equal_p (PATTERN (temp), PATTERN (temp1)))))
650 if (GET_CODE (temp1) == BARRIER)
652 reorder_insns (temp, temp, temp1);
653 temp1 = NEXT_INSN (temp1);
658 redirect_jump (insn, get_label_before (temp1));
659 reallabelprev = prev_real_insn (temp1);
663 /* Simplify if (...) x = a; else x = b; by converting it
664 to x = b; if (...) x = a;
665 if B is sufficiently simple, the test doesn't involve X,
666 and nothing in the test modifies B or X.
668 If we have small register classes, we also can't do this if X
671 If the "x = b;" insn has any REG_NOTES, we don't do this because
672 of the possibility that we are running after CSE and there is a
673 REG_EQUAL note that is only valid if the branch has already been
674 taken. If we move the insn with the REG_EQUAL note, we may
675 fold the comparison to always be false in a later CSE pass.
676 (We could also delete the REG_NOTES when moving the insn, but it
677 seems simpler to not move it.) An exception is that we can move
678 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
679 value is the same as "b".
681 INSN is the branch over the `else' part.
685 TEMP to the jump insn preceding "x = a;"
687 TEMP2 to the insn that sets "x = b;"
688 TEMP3 to the insn that sets "x = a;" */
690 if (this_is_simplejump
691 && (temp3 = prev_active_insn (insn)) != 0
692 && GET_CODE (temp3) == INSN
693 && GET_CODE (PATTERN (temp3)) == SET
694 && GET_CODE (temp1 = SET_DEST (PATTERN (temp3))) == REG
695 #ifdef SMALL_REGISTER_CLASSES
696 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
698 && (temp2 = next_active_insn (insn)) != 0
699 && GET_CODE (temp2) == INSN
700 && GET_CODE (PATTERN (temp2)) == SET
701 && rtx_equal_p (SET_DEST (PATTERN (temp2)), temp1)
702 && (GET_CODE (SET_SRC (PATTERN (temp2))) == REG
703 || GET_CODE (SET_SRC (PATTERN (temp2))) == SUBREG
704 || CONSTANT_P (SET_SRC (PATTERN (temp2))))
705 && (REG_NOTES (temp2) == 0
706 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
707 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
708 && XEXP (REG_NOTES (temp2), 1) == 0
709 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
710 SET_SRC (PATTERN (temp2)))))
711 && (temp = prev_active_insn (temp3)) != 0
712 && condjump_p (temp) && ! simplejump_p (temp)
713 /* TEMP must skip over the "x = a;" insn */
714 && prev_real_insn (JUMP_LABEL (temp)) == insn
715 && no_labels_between_p (insn, JUMP_LABEL (temp))
716 /* There must be no other entries to the "x = b;" insn. */
717 && no_labels_between_p (JUMP_LABEL (temp), temp2)
718 /* INSN must either branch to the insn after TEMP2 or the insn
719 after TEMP2 must branch to the same place as INSN. */
720 && (reallabelprev == temp2
721 || ((temp4 = next_active_insn (temp2)) != 0
722 && simplejump_p (temp4)
723 && JUMP_LABEL (temp4) == JUMP_LABEL (insn))))
725 /* The test expression, X, may be a complicated test with
726 multiple branches. See if we can find all the uses of
727 the label that TEMP branches to without hitting a CALL_INSN
728 or a jump to somewhere else. */
729 rtx target = JUMP_LABEL (temp);
730 int nuses = LABEL_NUSES (target);
733 /* Set P to the first jump insn that goes around "x = a;". */
734 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
736 if (GET_CODE (p) == JUMP_INSN)
738 if (condjump_p (p) && ! simplejump_p (p)
739 && JUMP_LABEL (p) == target)
748 else if (GET_CODE (p) == CALL_INSN)
753 /* We cannot insert anything between a set of cc and its use
754 so if P uses cc0, we must back up to the previous insn. */
755 q = prev_nonnote_insn (p);
756 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
757 && sets_cc0_p (PATTERN (q)))
764 /* If we found all the uses and there was no data conflict, we
765 can move the assignment unless we can branch into the middle
768 && no_labels_between_p (p, insn)
769 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
770 && ! reg_set_between_p (temp1, p, temp3)
771 && (GET_CODE (SET_SRC (PATTERN (temp2))) == CONST_INT
772 || ! reg_set_between_p (SET_SRC (PATTERN (temp2)),
775 reorder_insns_with_line_notes (temp2, temp2, p);
777 /* Set NEXT to an insn that we know won't go away. */
778 next = next_active_insn (insn);
780 /* Delete the jump around the set. Note that we must do
781 this before we redirect the test jumps so that it won't
782 delete the code immediately following the assignment
783 we moved (which might be a jump). */
787 /* We either have two consecutive labels or a jump to
788 a jump, so adjust all the JUMP_INSNs to branch to where
790 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
791 if (GET_CODE (p) == JUMP_INSN)
792 redirect_jump (p, target);
799 /* We deal with four cases:
801 1) x = a; if (...) x = b; and either A or B is zero,
802 2) if (...) x = 0; and jumps are expensive,
803 3) x = a; if (...) x = b; and A and B are constants where all the
804 set bits in A are also set in B and jumps are expensive, and
805 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
808 In each of these try to use a store-flag insn to avoid the jump.
809 (If the jump would be faster, the machine should not have
810 defined the scc insns!). These cases are often made by the
811 previous optimization.
813 INSN here is the jump around the store. We set:
815 TEMP to the "x = b;" insn.
817 TEMP2 to B (const0_rtx in the second case).
818 TEMP3 to A (X in the second case).
819 TEMP4 to the condition being tested.
820 TEMP5 to the earliest insn used to find the condition. */
822 if (/* We can't do this after reload has completed. */
824 && this_is_condjump && ! this_is_simplejump
825 /* Set TEMP to the "x = b;" insn. */
826 && (temp = next_nonnote_insn (insn)) != 0
827 && GET_CODE (temp) == INSN
828 && GET_CODE (PATTERN (temp)) == SET
829 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
830 #ifdef SMALL_REGISTER_CLASSES
831 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
833 && GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
834 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
835 || GET_CODE (temp2) == SUBREG
836 || GET_CODE (temp2) == CONST_INT)
837 /* Allow either form, but prefer the former if both apply. */
838 && (((temp3 = reg_set_last (temp1, insn)) != 0
839 && ((GET_CODE (temp3) == REG
840 #ifdef SMALL_REGISTER_CLASSES
841 && REGNO (temp3) >= FIRST_PSEUDO_REGISTER
844 || GET_CODE (temp3) == SUBREG
845 || GET_CODE (temp3) == CONST_INT))
846 /* Make the latter case look like x = x; if (...) x = 0; */
847 || ((temp3 = temp1, BRANCH_COST >= 2)
848 && temp2 == const0_rtx))
849 /* INSN must either branch to the insn after TEMP or the insn
850 after TEMP must branch to the same place as INSN. */
851 && (reallabelprev == temp
852 || ((temp4 = next_active_insn (temp)) != 0
853 && simplejump_p (temp4)
854 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
855 && (temp4 = get_condition (insn, &temp5)) != 0
857 /* If B is zero, OK; if A is zero, can only do (1) if we
858 can reverse the condition. See if (3) applies possibly
859 by reversing the condition. Prefer reversing to (4) when
860 branches are very expensive. */
861 && ((reversep = 0, temp2 == const0_rtx)
862 || (temp3 == const0_rtx
863 && (reversep = can_reverse_comparison_p (temp4, insn)))
865 && GET_CODE (temp2) == CONST_INT
866 && GET_CODE (temp3) == CONST_INT
867 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
868 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
869 && (reversep = can_reverse_comparison_p (temp4,
871 || BRANCH_COST >= 3))
873 enum rtx_code code = GET_CODE (temp4);
874 rtx uval, cval, var = temp1;
878 /* If necessary, reverse the condition. */
880 code = reverse_condition (code), uval = temp2, cval = temp3;
882 uval = temp3, cval = temp2;
884 /* See if we can do this with a store-flag insn. */
887 /* If CVAL is non-zero, normalize to -1. Otherwise,
888 if UVAL is the constant 1, it is best to just compute
889 the result directly. If UVAL is constant and STORE_FLAG_VALUE
890 includes all of its bits, it is best to compute the flag
891 value unnormalized and `and' it with UVAL. Otherwise,
892 normalize to -1 and `and' with UVAL. */
893 normalizep = (cval != const0_rtx ? -1
894 : (uval == const1_rtx ? 1
895 : (GET_CODE (uval) == CONST_INT
896 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
899 /* We will be putting the store-flag insn immediately in
900 front of the comparison that was originally being done,
901 so we know all the variables in TEMP4 will be valid.
902 However, this might be in front of the assignment of
903 A to VAR. If it is, it would clobber the store-flag
906 Therefore, emit into a temporary which will be copied to
907 VAR immediately after TEMP. */
909 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
910 XEXP (temp4, 0), XEXP (temp4, 1),
912 (code == LTU || code == LEU
913 || code == GEU || code == GTU),
919 /* Both CVAL and UVAL are non-zero. */
920 if (cval != const0_rtx && uval != const0_rtx)
924 tem1 = expand_and (uval, target, NULL_RTX);
925 if (GET_CODE (cval) == CONST_INT
926 && GET_CODE (uval) == CONST_INT
927 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
931 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
932 target, NULL_RTX, 0);
933 tem2 = expand_and (cval, tem2, tem2);
936 /* If we usually make new pseudos, do so here. This
937 turns out to help machines that have conditional
940 if (flag_expensive_optimizations)
943 target = expand_binop (GET_MODE (var), ior_optab,
947 else if (normalizep != 1)
948 target = expand_and (uval, target,
949 (GET_CODE (target) == REG
950 && ! preserve_subexpressions_p ()
951 ? target : NULL_RTX));
953 seq = gen_sequence ();
955 emit_insn_before (seq, temp5);
956 emit_insn_after (gen_move_insn (var, target), insn);
958 next = NEXT_INSN (insn);
960 delete_insn (prev_nonnote_insn (insn));
970 /* If branches are expensive, convert
971 if (foo) bar++; to bar += (foo != 0);
972 and similarly for "bar--;"
974 INSN is the conditional branch around the arithmetic. We set:
976 TEMP is the arithmetic insn.
977 TEMP1 is the SET doing the arithmetic.
978 TEMP2 is the operand being incremented or decremented.
979 TEMP3 to the condition being tested.
980 TEMP4 to the earliest insn used to find the condition. */
983 && ! reload_completed
984 && this_is_condjump && ! this_is_simplejump
985 && (temp = next_nonnote_insn (insn)) != 0
986 && (temp1 = single_set (temp)) != 0
987 && (temp2 = SET_DEST (temp1),
988 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
989 && GET_CODE (SET_SRC (temp1)) == PLUS
990 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
991 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
992 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
993 /* INSN must either branch to the insn after TEMP or the insn
994 after TEMP must branch to the same place as INSN. */
995 && (reallabelprev == temp
996 || ((temp3 = next_active_insn (temp)) != 0
997 && simplejump_p (temp3)
998 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
999 && (temp3 = get_condition (insn, &temp4)) != 0
1000 && can_reverse_comparison_p (temp3, insn))
1002 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1003 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1007 /* It must be the case that TEMP2 is not modified in the range
1008 [TEMP4, INSN). The one exception we make is if the insn
1009 before INSN sets TEMP2 to something which is also unchanged
1010 in that range. In that case, we can move the initialization
1011 into our sequence. */
1013 if ((temp5 = prev_active_insn (insn)) != 0
1014 && GET_CODE (temp5) == INSN
1015 && (temp6 = single_set (temp5)) != 0
1016 && rtx_equal_p (temp2, SET_DEST (temp6))
1017 && (CONSTANT_P (SET_SRC (temp6))
1018 || GET_CODE (SET_SRC (temp6)) == REG
1019 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1021 emit_insn (PATTERN (temp5));
1023 init = SET_SRC (temp6);
1026 if (CONSTANT_P (init)
1027 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1028 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1029 XEXP (temp3, 0), XEXP (temp3, 1),
1031 (code == LTU || code == LEU
1032 || code == GTU || code == GEU), 1);
1034 /* If we can do the store-flag, do the addition or
1038 target = expand_binop (GET_MODE (temp2),
1039 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1040 ? add_optab : sub_optab),
1041 temp2, target, temp2, OPTAB_WIDEN);
1045 /* Put the result back in temp2 in case it isn't already.
1046 Then replace the jump, possible a CC0-setting insn in
1047 front of the jump, and TEMP, with the sequence we have
1050 if (target != temp2)
1051 emit_move_insn (temp2, target);
1056 emit_insns_before (seq, temp4);
1060 delete_insn (init_insn);
1062 next = NEXT_INSN (insn);
1064 delete_insn (prev_nonnote_insn (insn));
1074 /* Simplify if (...) x = 1; else {...} if (x) ...
1075 We recognize this case scanning backwards as well.
1077 TEMP is the assignment to x;
1078 TEMP1 is the label at the head of the second if. */
1079 /* ?? This should call get_condition to find the values being
1080 compared, instead of looking for a COMPARE insn when HAVE_cc0
1081 is not defined. This would allow it to work on the m88k. */
1082 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1083 is not defined and the condition is tested by a separate compare
1084 insn. This is because the code below assumes that the result
1085 of the compare dies in the following branch.
1087 Not only that, but there might be other insns between the
1088 compare and branch whose results are live. Those insns need
1091 A way to fix this is to move the insns at JUMP_LABEL (insn)
1092 to before INSN. If we are running before flow, they will
1093 be deleted if they aren't needed. But this doesn't work
1096 This is really a special-case of jump threading, anyway. The
1097 right thing to do is to replace this and jump threading with
1098 much simpler code in cse.
1100 This code has been turned off in the non-cc0 case in the
1104 else if (this_is_simplejump
1105 /* Safe to skip USE and CLOBBER insns here
1106 since they will not be deleted. */
1107 && (temp = prev_active_insn (insn))
1108 && no_labels_between_p (temp, insn)
1109 && GET_CODE (temp) == INSN
1110 && GET_CODE (PATTERN (temp)) == SET
1111 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1112 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1113 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1114 /* If we find that the next value tested is `x'
1115 (TEMP1 is the insn where this happens), win. */
1116 && GET_CODE (temp1) == INSN
1117 && GET_CODE (PATTERN (temp1)) == SET
1119 /* Does temp1 `tst' the value of x? */
1120 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1121 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1122 && (temp1 = next_nonnote_insn (temp1))
1124 /* Does temp1 compare the value of x against zero? */
1125 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1126 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1127 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1128 == SET_DEST (PATTERN (temp)))
1129 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1130 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1132 && condjump_p (temp1))
1134 /* Get the if_then_else from the condjump. */
1135 rtx choice = SET_SRC (PATTERN (temp1));
1136 if (GET_CODE (choice) == IF_THEN_ELSE)
1138 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1139 rtx val = SET_SRC (PATTERN (temp));
1141 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1145 if (cond == const_true_rtx)
1146 ultimate = XEXP (choice, 1);
1147 else if (cond == const0_rtx)
1148 ultimate = XEXP (choice, 2);
1152 if (ultimate == pc_rtx)
1153 ultimate = get_label_after (temp1);
1154 else if (ultimate && GET_CODE (ultimate) != RETURN)
1155 ultimate = XEXP (ultimate, 0);
1158 changed |= redirect_jump (insn, ultimate);
1164 /* @@ This needs a bit of work before it will be right.
1166 Any type of comparison can be accepted for the first and
1167 second compare. When rewriting the first jump, we must
1168 compute the what conditions can reach label3, and use the
1169 appropriate code. We can not simply reverse/swap the code
1170 of the first jump. In some cases, the second jump must be
1174 < == converts to > ==
1175 < != converts to == >
1178 If the code is written to only accept an '==' test for the second
1179 compare, then all that needs to be done is to swap the condition
1180 of the first branch.
1182 It is questionable whether we want this optimization anyways,
1183 since if the user wrote code like this because he/she knew that
1184 the jump to label1 is taken most of the time, then rewriting
1185 this gives slower code. */
1186 /* @@ This should call get_condition to find the values being
1187 compared, instead of looking for a COMPARE insn when HAVE_cc0
1188 is not defined. This would allow it to work on the m88k. */
1189 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1190 is not defined and the condition is tested by a separate compare
1191 insn. This is because the code below assumes that the result
1192 of the compare dies in the following branch. */
1194 /* Simplify test a ~= b
1208 where ~= is an inequality, e.g. >, and ~~= is the swapped
1211 We recognize this case scanning backwards.
1213 TEMP is the conditional jump to `label2';
1214 TEMP1 is the test for `a == b';
1215 TEMP2 is the conditional jump to `label1';
1216 TEMP3 is the test for `a ~= b'. */
1217 else if (this_is_simplejump
1218 && (temp = prev_active_insn (insn))
1219 && no_labels_between_p (temp, insn)
1220 && condjump_p (temp)
1221 && (temp1 = prev_active_insn (temp))
1222 && no_labels_between_p (temp1, temp)
1223 && GET_CODE (temp1) == INSN
1224 && GET_CODE (PATTERN (temp1)) == SET
1226 && sets_cc0_p (PATTERN (temp1)) == 1
1228 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1229 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1230 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1232 && (temp2 = prev_active_insn (temp1))
1233 && no_labels_between_p (temp2, temp1)
1234 && condjump_p (temp2)
1235 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1236 && (temp3 = prev_active_insn (temp2))
1237 && no_labels_between_p (temp3, temp2)
1238 && GET_CODE (PATTERN (temp3)) == SET
1239 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1240 SET_DEST (PATTERN (temp1)))
1241 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1242 SET_SRC (PATTERN (temp3)))
1243 && ! inequality_comparisons_p (PATTERN (temp))
1244 && inequality_comparisons_p (PATTERN (temp2)))
1246 rtx fallthrough_label = JUMP_LABEL (temp2);
1248 ++LABEL_NUSES (fallthrough_label);
1249 if (swap_jump (temp2, JUMP_LABEL (insn)))
1255 if (--LABEL_NUSES (fallthrough_label) == 0)
1256 delete_insn (fallthrough_label);
1259 /* Simplify if (...) {... x = 1;} if (x) ...
1261 We recognize this case backwards.
1263 TEMP is the test of `x';
1264 TEMP1 is the assignment to `x' at the end of the
1265 previous statement. */
1266 /* @@ This should call get_condition to find the values being
1267 compared, instead of looking for a COMPARE insn when HAVE_cc0
1268 is not defined. This would allow it to work on the m88k. */
1269 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1270 is not defined and the condition is tested by a separate compare
1271 insn. This is because the code below assumes that the result
1272 of the compare dies in the following branch. */
1274 /* ??? This has to be turned off. The problem is that the
1275 unconditional jump might indirectly end up branching to the
1276 label between TEMP1 and TEMP. We can't detect this, in general,
1277 since it may become a jump to there after further optimizations.
1278 If that jump is done, it will be deleted, so we will retry
1279 this optimization in the next pass, thus an infinite loop.
1281 The present code prevents this by putting the jump after the
1282 label, but this is not logically correct. */
1284 else if (this_is_condjump
1285 /* Safe to skip USE and CLOBBER insns here
1286 since they will not be deleted. */
1287 && (temp = prev_active_insn (insn))
1288 && no_labels_between_p (temp, insn)
1289 && GET_CODE (temp) == INSN
1290 && GET_CODE (PATTERN (temp)) == SET
1292 && sets_cc0_p (PATTERN (temp)) == 1
1293 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1295 /* Temp must be a compare insn, we can not accept a register
1296 to register move here, since it may not be simply a
1298 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1299 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1300 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1301 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1302 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1304 /* May skip USE or CLOBBER insns here
1305 for checking for opportunity, since we
1306 take care of them later. */
1307 && (temp1 = prev_active_insn (temp))
1308 && GET_CODE (temp1) == INSN
1309 && GET_CODE (PATTERN (temp1)) == SET
1311 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1313 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1314 == SET_DEST (PATTERN (temp1)))
1316 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1317 /* If this isn't true, cse will do the job. */
1318 && ! no_labels_between_p (temp1, temp))
1320 /* Get the if_then_else from the condjump. */
1321 rtx choice = SET_SRC (PATTERN (insn));
1322 if (GET_CODE (choice) == IF_THEN_ELSE
1323 && (GET_CODE (XEXP (choice, 0)) == EQ
1324 || GET_CODE (XEXP (choice, 0)) == NE))
1326 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1331 /* Get the place that condjump will jump to
1332 if it is reached from here. */
1333 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1335 ultimate = XEXP (choice, 1);
1337 ultimate = XEXP (choice, 2);
1338 /* Get it as a CODE_LABEL. */
1339 if (ultimate == pc_rtx)
1340 ultimate = get_label_after (insn);
1342 /* Get the label out of the LABEL_REF. */
1343 ultimate = XEXP (ultimate, 0);
1345 /* Insert the jump immediately before TEMP, specifically
1346 after the label that is between TEMP1 and TEMP. */
1347 last_insn = PREV_INSN (temp);
1349 /* If we would be branching to the next insn, the jump
1350 would immediately be deleted and the re-inserted in
1351 a subsequent pass over the code. So don't do anything
1353 if (next_active_insn (last_insn)
1354 != next_active_insn (ultimate))
1356 emit_barrier_after (last_insn);
1357 p = emit_jump_insn_after (gen_jump (ultimate),
1359 JUMP_LABEL (p) = ultimate;
1360 ++LABEL_NUSES (ultimate);
1361 if (INSN_UID (ultimate) < max_jump_chain
1362 && INSN_CODE (p) < max_jump_chain)
1364 jump_chain[INSN_UID (p)]
1365 = jump_chain[INSN_UID (ultimate)];
1366 jump_chain[INSN_UID (ultimate)] = p;
1374 /* Detect a conditional jump going to the same place
1375 as an immediately following unconditional jump. */
1376 else if (this_is_condjump
1377 && (temp = next_active_insn (insn)) != 0
1378 && simplejump_p (temp)
1379 && (next_active_insn (JUMP_LABEL (insn))
1380 == next_active_insn (JUMP_LABEL (temp))))
1386 /* Detect a conditional jump jumping over an unconditional jump. */
1388 else if (this_is_condjump && ! this_is_simplejump
1389 && reallabelprev != 0
1390 && GET_CODE (reallabelprev) == JUMP_INSN
1391 && prev_active_insn (reallabelprev) == insn
1392 && no_labels_between_p (insn, reallabelprev)
1393 && simplejump_p (reallabelprev))
1395 /* When we invert the unconditional jump, we will be
1396 decrementing the usage count of its old label.
1397 Make sure that we don't delete it now because that
1398 might cause the following code to be deleted. */
1399 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1400 rtx prev_label = JUMP_LABEL (insn);
1402 ++LABEL_NUSES (prev_label);
1404 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1406 /* It is very likely that if there are USE insns before
1407 this jump, they hold REG_DEAD notes. These REG_DEAD
1408 notes are no longer valid due to this optimization,
1409 and will cause the life-analysis that following passes
1410 (notably delayed-branch scheduling) to think that
1411 these registers are dead when they are not.
1413 To prevent this trouble, we just remove the USE insns
1414 from the insn chain. */
1416 while (prev_uses && GET_CODE (prev_uses) == INSN
1417 && GET_CODE (PATTERN (prev_uses)) == USE)
1419 rtx useless = prev_uses;
1420 prev_uses = prev_nonnote_insn (prev_uses);
1421 delete_insn (useless);
1424 delete_insn (reallabelprev);
1429 /* We can now safely delete the label if it is unreferenced
1430 since the delete_insn above has deleted the BARRIER. */
1431 if (--LABEL_NUSES (prev_label) == 0)
1432 delete_insn (prev_label);
1437 /* Detect a jump to a jump. */
1439 nlabel = follow_jumps (JUMP_LABEL (insn));
1440 if (nlabel != JUMP_LABEL (insn)
1441 && redirect_jump (insn, nlabel))
1447 /* Look for if (foo) bar; else break; */
1448 /* The insns look like this:
1449 insn = condjump label1;
1450 ...range1 (some insns)...
1453 ...range2 (some insns)...
1454 jump somewhere unconditionally
1457 rtx label1 = next_label (insn);
1458 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1459 /* Don't do this optimization on the first round, so that
1460 jump-around-a-jump gets simplified before we ask here
1461 whether a jump is unconditional.
1463 Also don't do it when we are called after reload since
1464 it will confuse reorg. */
1466 && (reload_completed ? ! flag_delayed_branch : 1)
1467 /* Make sure INSN is something we can invert. */
1468 && condjump_p (insn)
1470 && JUMP_LABEL (insn) == label1
1471 && LABEL_NUSES (label1) == 1
1472 && GET_CODE (range1end) == JUMP_INSN
1473 && simplejump_p (range1end))
1475 rtx label2 = next_label (label1);
1476 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1477 if (range1end != range2end
1478 && JUMP_LABEL (range1end) == label2
1479 && GET_CODE (range2end) == JUMP_INSN
1480 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1481 /* Invert the jump condition, so we
1482 still execute the same insns in each case. */
1483 && invert_jump (insn, label1))
1485 rtx range1beg = next_active_insn (insn);
1486 rtx range2beg = next_active_insn (label1);
1487 rtx range1after, range2after;
1488 rtx range1before, range2before;
1490 /* Include in each range any line number before it. */
1491 while (PREV_INSN (range1beg)
1492 && GET_CODE (PREV_INSN (range1beg)) == NOTE
1493 && NOTE_LINE_NUMBER (PREV_INSN (range1beg)) > 0)
1494 range1beg = PREV_INSN (range1beg);
1496 while (PREV_INSN (range2beg)
1497 && GET_CODE (PREV_INSN (range2beg)) == NOTE
1498 && NOTE_LINE_NUMBER (PREV_INSN (range2beg)) > 0)
1499 range2beg = PREV_INSN (range2beg);
1501 /* Don't move NOTEs for blocks or loops; shift them
1502 outside the ranges, where they'll stay put. */
1503 range1beg = squeeze_notes (range1beg, range1end);
1504 range2beg = squeeze_notes (range2beg, range2end);
1506 /* Get current surrounds of the 2 ranges. */
1507 range1before = PREV_INSN (range1beg);
1508 range2before = PREV_INSN (range2beg);
1509 range1after = NEXT_INSN (range1end);
1510 range2after = NEXT_INSN (range2end);
1512 /* Splice range2 where range1 was. */
1513 NEXT_INSN (range1before) = range2beg;
1514 PREV_INSN (range2beg) = range1before;
1515 NEXT_INSN (range2end) = range1after;
1516 PREV_INSN (range1after) = range2end;
1517 /* Splice range1 where range2 was. */
1518 NEXT_INSN (range2before) = range1beg;
1519 PREV_INSN (range1beg) = range2before;
1520 NEXT_INSN (range1end) = range2after;
1521 PREV_INSN (range2after) = range1end;
1528 /* Now that the jump has been tensioned,
1529 try cross jumping: check for identical code
1530 before the jump and before its target label. */
1532 /* First, cross jumping of conditional jumps: */
1534 if (cross_jump && condjump_p (insn))
1536 rtx newjpos, newlpos;
1537 rtx x = prev_real_insn (JUMP_LABEL (insn));
1539 /* A conditional jump may be crossjumped
1540 only if the place it jumps to follows
1541 an opposing jump that comes back here. */
1543 if (x != 0 && ! jump_back_p (x, insn))
1544 /* We have no opposing jump;
1545 cannot cross jump this insn. */
1549 /* TARGET is nonzero if it is ok to cross jump
1550 to code before TARGET. If so, see if matches. */
1552 find_cross_jump (insn, x, 2,
1553 &newjpos, &newlpos);
1557 do_cross_jump (insn, newjpos, newlpos);
1558 /* Make the old conditional jump
1559 into an unconditional one. */
1560 SET_SRC (PATTERN (insn))
1561 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
1562 INSN_CODE (insn) = -1;
1563 emit_barrier_after (insn);
1564 /* Add to jump_chain unless this is a new label
1565 whose UID is too large. */
1566 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1568 jump_chain[INSN_UID (insn)]
1569 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1570 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1577 /* Cross jumping of unconditional jumps:
1578 a few differences. */
1580 if (cross_jump && simplejump_p (insn))
1582 rtx newjpos, newlpos;
1587 /* TARGET is nonzero if it is ok to cross jump
1588 to code before TARGET. If so, see if matches. */
1589 find_cross_jump (insn, JUMP_LABEL (insn), 1,
1590 &newjpos, &newlpos);
1592 /* If cannot cross jump to code before the label,
1593 see if we can cross jump to another jump to
1595 /* Try each other jump to this label. */
1596 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
1597 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1598 target != 0 && newjpos == 0;
1599 target = jump_chain[INSN_UID (target)])
1601 && JUMP_LABEL (target) == JUMP_LABEL (insn)
1602 /* Ignore TARGET if it's deleted. */
1603 && ! INSN_DELETED_P (target))
1604 find_cross_jump (insn, target, 2,
1605 &newjpos, &newlpos);
1609 do_cross_jump (insn, newjpos, newlpos);
1615 /* This code was dead in the previous jump.c! */
1616 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
1618 /* Return insns all "jump to the same place"
1619 so we can cross-jump between any two of them. */
1621 rtx newjpos, newlpos, target;
1625 /* If cannot cross jump to code before the label,
1626 see if we can cross jump to another jump to
1628 /* Try each other jump to this label. */
1629 for (target = jump_chain[0];
1630 target != 0 && newjpos == 0;
1631 target = jump_chain[INSN_UID (target)])
1633 && ! INSN_DELETED_P (target)
1634 && GET_CODE (PATTERN (target)) == RETURN)
1635 find_cross_jump (insn, target, 2,
1636 &newjpos, &newlpos);
1640 do_cross_jump (insn, newjpos, newlpos);
1651 /* Delete extraneous line number notes.
1652 Note that two consecutive notes for different lines are not really
1653 extraneous. There should be some indication where that line belonged,
1654 even if it became empty. */
1659 for (insn = f; insn; insn = NEXT_INSN (insn))
1660 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
1662 /* Delete this note if it is identical to previous note. */
1664 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
1665 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
1675 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
1676 If so, delete it, and record that this function can drop off the end. */
1682 /* One label can follow the end-note: the return label. */
1683 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
1684 /* Ordinary insns can follow it if returning a structure. */
1685 || GET_CODE (insn) == INSN
1686 /* If machine uses explicit RETURN insns, no epilogue,
1687 then one of them follows the note. */
1688 || (GET_CODE (insn) == JUMP_INSN
1689 && GET_CODE (PATTERN (insn)) == RETURN)
1690 /* Other kinds of notes can follow also. */
1691 || (GET_CODE (insn) == NOTE
1692 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
1693 insn = PREV_INSN (insn);
1696 /* Report if control can fall through at the end of the function. */
1697 if (insn && GET_CODE (insn) == NOTE
1698 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
1704 /* Show JUMP_CHAIN no longer valid. */
1708 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
1709 jump. Assume that this unconditional jump is to the exit test code. If
1710 the code is sufficiently simple, make a copy of it before INSN,
1711 followed by a jump to the exit of the loop. Then delete the unconditional
1714 Note that it is possible we can get confused here if the jump immediately
1715 after the loop start branches outside the loop but within an outer loop.
1716 If we are near the exit of that loop, we will copy its exit test. This
1717 will not generate incorrect code, but could suppress some optimizations.
1718 However, such cases are degenerate loops anyway.
1720 Return 1 if we made the change, else 0.
1722 This is only safe immediately after a regscan pass because it uses the
1723 values of regno_first_uid and regno_last_uid. */
1726 duplicate_loop_exit_test (loop_start)
1732 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
1734 int max_reg = max_reg_num ();
1737 /* Scan the exit code. We do not perform this optimization if any insn:
1741 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
1742 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
1743 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
1746 Also, don't do this if the exit code is more than 20 insns. */
1748 for (insn = exitcode;
1750 && ! (GET_CODE (insn) == NOTE
1751 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
1752 insn = NEXT_INSN (insn))
1754 switch (GET_CODE (insn))
1760 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1761 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1762 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
1767 if (++num_insns > 20
1768 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1769 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
1775 /* Unless INSN is zero, we can do the optimization. */
1781 /* See if any insn sets a register only used in the loop exit code and
1782 not a user variable. If so, replace it with a new register. */
1783 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1784 if (GET_CODE (insn) == INSN
1785 && (set = single_set (insn)) != 0
1786 && GET_CODE (SET_DEST (set)) == REG
1787 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
1788 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn))
1790 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
1791 if (regno_last_uid[REGNO (SET_DEST (set))] == INSN_UID (p))
1796 /* We can do the replacement. Allocate reg_map if this is the
1797 first replacement we found. */
1800 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
1801 bzero (reg_map, max_reg * sizeof (rtx));
1804 REG_LOOP_TEST_P (SET_DEST (set)) = 1;
1806 reg_map[REGNO (SET_DEST (set))]
1807 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
1811 /* Now copy each insn. */
1812 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
1813 switch (GET_CODE (insn))
1816 copy = emit_barrier_before (loop_start);
1819 /* Only copy line-number notes. */
1820 if (NOTE_LINE_NUMBER (insn) >= 0)
1822 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
1823 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
1828 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
1830 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1832 mark_jump_label (PATTERN (copy), copy, 0);
1834 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
1836 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1837 if (REG_NOTE_KIND (link) != REG_LABEL)
1839 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
1840 XEXP (link, 0), REG_NOTES (copy)));
1841 if (reg_map && REG_NOTES (copy))
1842 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1846 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
1848 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
1849 mark_jump_label (PATTERN (copy), copy, 0);
1850 if (REG_NOTES (insn))
1852 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
1854 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
1857 /* If this is a simple jump, add it to the jump chain. */
1859 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
1860 && simplejump_p (copy))
1862 jump_chain[INSN_UID (copy)]
1863 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1864 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1872 /* Now clean up by emitting a jump to the end label and deleting the jump
1873 at the start of the loop. */
1874 if (GET_CODE (copy) != BARRIER)
1876 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
1878 mark_jump_label (PATTERN (copy), copy, 0);
1879 if (INSN_UID (copy) < max_jump_chain
1880 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
1882 jump_chain[INSN_UID (copy)]
1883 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
1884 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
1886 emit_barrier_before (loop_start);
1889 delete_insn (next_nonnote_insn (loop_start));
1891 /* Mark the exit code as the virtual top of the converted loop. */
1892 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
1897 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
1898 loop-end notes between START and END out before START. Assume that
1899 END is not such a note. START may be such a note. Returns the value
1900 of the new starting insn, which may be different if the original start
1904 squeeze_notes (start, end)
1910 for (insn = start; insn != end; insn = next)
1912 next = NEXT_INSN (insn);
1913 if (GET_CODE (insn) == NOTE
1914 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
1915 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
1916 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
1917 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
1918 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
1919 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
1925 rtx prev = PREV_INSN (insn);
1926 PREV_INSN (insn) = PREV_INSN (start);
1927 NEXT_INSN (insn) = start;
1928 NEXT_INSN (PREV_INSN (insn)) = insn;
1929 PREV_INSN (NEXT_INSN (insn)) = insn;
1930 NEXT_INSN (prev) = next;
1931 PREV_INSN (next) = prev;
1939 /* Compare the instructions before insn E1 with those before E2
1940 to find an opportunity for cross jumping.
1941 (This means detecting identical sequences of insns followed by
1942 jumps to the same place, or followed by a label and a jump
1943 to that label, and replacing one with a jump to the other.)
1945 Assume E1 is a jump that jumps to label E2
1946 (that is not always true but it might as well be).
1947 Find the longest possible equivalent sequences
1948 and store the first insns of those sequences into *F1 and *F2.
1949 Store zero there if no equivalent preceding instructions are found.
1951 We give up if we find a label in stream 1.
1952 Actually we could transfer that label into stream 2. */
1955 find_cross_jump (e1, e2, minimum, f1, f2)
1960 register rtx i1 = e1, i2 = e2;
1961 register rtx p1, p2;
1964 rtx last1 = 0, last2 = 0;
1965 rtx afterlast1 = 0, afterlast2 = 0;
1973 i1 = prev_nonnote_insn (i1);
1975 i2 = PREV_INSN (i2);
1976 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
1977 i2 = PREV_INSN (i2);
1982 /* Don't allow the range of insns preceding E1 or E2
1983 to include the other (E2 or E1). */
1984 if (i2 == e1 || i1 == e2)
1987 /* If we will get to this code by jumping, those jumps will be
1988 tensioned to go directly to the new label (before I2),
1989 so this cross-jumping won't cost extra. So reduce the minimum. */
1990 if (GET_CODE (i1) == CODE_LABEL)
1996 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2003 /* If cross_jump_death_matters is not 0, the insn's mode
2004 indicates whether or not the insn contains any stack-like
2007 if (cross_jump_death_matters && GET_MODE (i1) == QImode)
2009 /* If register stack conversion has already been done, then
2010 death notes must also be compared before it is certain that
2011 the two instruction streams match. */
2014 HARD_REG_SET i1_regset, i2_regset;
2016 CLEAR_HARD_REG_SET (i1_regset);
2017 CLEAR_HARD_REG_SET (i2_regset);
2019 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2020 if (REG_NOTE_KIND (note) == REG_DEAD
2021 && STACK_REG_P (XEXP (note, 0)))
2022 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2024 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2025 if (REG_NOTE_KIND (note) == REG_DEAD
2026 && STACK_REG_P (XEXP (note, 0)))
2027 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2029 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2038 if (lose || GET_CODE (p1) != GET_CODE (p2)
2039 || ! rtx_renumbered_equal_p (p1, p2))
2041 /* The following code helps take care of G++ cleanups. */
2045 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2046 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2047 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2048 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2049 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2050 /* If the equivalences are not to a constant, they may
2051 reference pseudos that no longer exist, so we can't
2053 && CONSTANT_P (XEXP (equiv1, 0))
2054 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2056 rtx s1 = single_set (i1);
2057 rtx s2 = single_set (i2);
2058 if (s1 != 0 && s2 != 0
2059 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2061 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2062 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2063 if (! rtx_renumbered_equal_p (p1, p2))
2065 else if (apply_change_group ())
2070 /* Insns fail to match; cross jumping is limited to the following
2074 /* Don't allow the insn after a compare to be shared by
2075 cross-jumping unless the compare is also shared.
2076 Here, if either of these non-matching insns is a compare,
2077 exclude the following insn from possible cross-jumping. */
2078 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2079 last1 = afterlast1, last2 = afterlast2, ++minimum;
2082 /* If cross-jumping here will feed a jump-around-jump
2083 optimization, this jump won't cost extra, so reduce
2085 if (GET_CODE (i1) == JUMP_INSN
2087 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2093 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2095 /* Ok, this insn is potentially includable in a cross-jump here. */
2096 afterlast1 = last1, afterlast2 = last2;
2097 last1 = i1, last2 = i2, --minimum;
2101 /* We have to be careful that we do not cross-jump into the middle of
2102 USE-CALL_INSN-CLOBBER sequence. This sequence is used instead of
2103 putting the USE and CLOBBERs inside the CALL_INSN. The delay slot
2104 scheduler needs to know what registers are used and modified by the
2105 CALL_INSN and needs the adjacent USE and CLOBBERs to do so.
2107 ??? At some point we should probably change this so that these are
2108 part of the CALL_INSN. The way we are doing it now is a kludge that
2109 is now causing trouble. */
2111 if (last1 != 0 && GET_CODE (last1) == CALL_INSN
2112 && (prev1 = prev_nonnote_insn (last1))
2113 && GET_CODE (prev1) == INSN
2114 && GET_CODE (PATTERN (prev1)) == USE)
2116 /* Remove this CALL_INSN from the range we can cross-jump. */
2117 last1 = next_real_insn (last1);
2118 last2 = next_real_insn (last2);
2123 /* Skip past CLOBBERS since they may be right after a CALL_INSN. It
2124 isn't worth checking for the CALL_INSN. */
2125 while (last1 != 0 && GET_CODE (PATTERN (last1)) == CLOBBER)
2126 last1 = next_real_insn (last1), last2 = next_real_insn (last2);
2128 if (minimum <= 0 && last1 != 0 && last1 != e1)
2129 *f1 = last1, *f2 = last2;
2133 do_cross_jump (insn, newjpos, newlpos)
2134 rtx insn, newjpos, newlpos;
2136 /* Find an existing label at this point
2137 or make a new one if there is none. */
2138 register rtx label = get_label_before (newlpos);
2140 /* Make the same jump insn jump to the new point. */
2141 if (GET_CODE (PATTERN (insn)) == RETURN)
2143 /* Remove from jump chain of returns. */
2144 delete_from_jump_chain (insn);
2145 /* Change the insn. */
2146 PATTERN (insn) = gen_jump (label);
2147 INSN_CODE (insn) = -1;
2148 JUMP_LABEL (insn) = label;
2149 LABEL_NUSES (label)++;
2150 /* Add to new the jump chain. */
2151 if (INSN_UID (label) < max_jump_chain
2152 && INSN_UID (insn) < max_jump_chain)
2154 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2155 jump_chain[INSN_UID (label)] = insn;
2159 redirect_jump (insn, label);
2161 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2162 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2163 the NEWJPOS stream. */
2165 while (newjpos != insn)
2169 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2170 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2171 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2172 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2173 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2174 remove_note (newlpos, lnote);
2176 delete_insn (newjpos);
2177 newjpos = next_real_insn (newjpos);
2178 newlpos = next_real_insn (newlpos);
2182 /* Return the label before INSN, or put a new label there. */
2185 get_label_before (insn)
2190 /* Find an existing label at this point
2191 or make a new one if there is none. */
2192 label = prev_nonnote_insn (insn);
2194 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2196 rtx prev = PREV_INSN (insn);
2198 /* Don't put a label between a CALL_INSN and USE insns that precede
2201 if (GET_CODE (insn) == CALL_INSN
2202 || (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SEQUENCE
2203 && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == CALL_INSN))
2204 while (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == USE)
2205 prev = PREV_INSN (prev);
2207 label = gen_label_rtx ();
2208 emit_label_after (label, prev);
2209 LABEL_NUSES (label) = 0;
2214 /* Return the label after INSN, or put a new label there. */
2217 get_label_after (insn)
2222 /* Find an existing label at this point
2223 or make a new one if there is none. */
2224 label = next_nonnote_insn (insn);
2226 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2228 /* Don't put a label between a CALL_INSN and CLOBBER insns
2231 if (GET_CODE (insn) == CALL_INSN
2232 || (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SEQUENCE
2233 && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == CALL_INSN))
2234 while (GET_CODE (NEXT_INSN (insn)) == INSN
2235 && GET_CODE (PATTERN (NEXT_INSN (insn))) == CLOBBER)
2236 insn = NEXT_INSN (insn);
2238 label = gen_label_rtx ();
2239 emit_label_after (label, insn);
2240 LABEL_NUSES (label) = 0;
2245 /* Return 1 if INSN is a jump that jumps to right after TARGET
2246 only on the condition that TARGET itself would drop through.
2247 Assumes that TARGET is a conditional jump. */
2250 jump_back_p (insn, target)
2254 enum rtx_code codei, codet;
2256 if (simplejump_p (insn) || ! condjump_p (insn)
2257 || simplejump_p (target)
2258 || target != prev_real_insn (JUMP_LABEL (insn)))
2261 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2262 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2264 codei = GET_CODE (cinsn);
2265 codet = GET_CODE (ctarget);
2267 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2269 if (! can_reverse_comparison_p (cinsn, insn))
2271 codei = reverse_condition (codei);
2274 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2276 if (! can_reverse_comparison_p (ctarget, target))
2278 codet = reverse_condition (codet);
2281 return (codei == codet
2282 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2283 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2286 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2287 return non-zero if it is safe to reverse this comparison. It is if our
2288 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2289 this is known to be an integer comparison. */
2292 can_reverse_comparison_p (comparison, insn)
2298 /* If this is not actually a comparison, we can't reverse it. */
2299 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2302 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2303 /* If this is an NE comparison, it is safe to reverse it to an EQ
2304 comparison and vice versa, even for floating point. If no operands
2305 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2306 always false and NE is always true, so the reversal is also valid. */
2307 || GET_CODE (comparison) == NE
2308 || GET_CODE (comparison) == EQ)
2311 arg0 = XEXP (comparison, 0);
2313 /* Make sure ARG0 is one of the actual objects being compared. If we
2314 can't do this, we can't be sure the comparison can be reversed.
2316 Handle cc0 and a MODE_CC register. */
2317 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2323 rtx prev = prev_nonnote_insn (insn);
2324 rtx set = single_set (prev);
2326 if (set == 0 || SET_DEST (set) != arg0)
2329 arg0 = SET_SRC (set);
2331 if (GET_CODE (arg0) == COMPARE)
2332 arg0 = XEXP (arg0, 0);
2335 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2336 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2337 return (GET_CODE (arg0) == CONST_INT
2338 || (GET_MODE (arg0) != VOIDmode
2339 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2340 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2343 /* Given an rtx-code for a comparison, return the code
2344 for the negated comparison.
2345 WATCH OUT! reverse_condition is not safe to use on a jump
2346 that might be acting on the results of an IEEE floating point comparison,
2347 because of the special treatment of non-signaling nans in comparisons.
2348 Use can_reverse_comparison_p to be sure. */
2351 reverse_condition (code)
2392 /* Similar, but return the code when two operands of a comparison are swapped.
2393 This IS safe for IEEE floating-point. */
2396 swap_condition (code)
2435 /* Given a comparison CODE, return the corresponding unsigned comparison.
2436 If CODE is an equality comparison or already an unsigned comparison,
2437 CODE is returned. */
2440 unsigned_condition (code)
2470 /* Similarly, return the signed version of a comparison. */
2473 signed_condition (code)
2503 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2504 truth of CODE1 implies the truth of CODE2. */
2507 comparison_dominates_p (code1, code2)
2508 enum rtx_code code1, code2;
2516 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
2544 /* Return 1 if INSN is an unconditional jump and nothing else. */
2550 return (GET_CODE (insn) == JUMP_INSN
2551 && GET_CODE (PATTERN (insn)) == SET
2552 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2553 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2556 /* Return nonzero if INSN is a (possibly) conditional jump
2557 and nothing more. */
2563 register rtx x = PATTERN (insn);
2564 if (GET_CODE (x) != SET)
2566 if (GET_CODE (SET_DEST (x)) != PC)
2568 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2570 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2572 if (XEXP (SET_SRC (x), 2) == pc_rtx
2573 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2574 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2576 if (XEXP (SET_SRC (x), 1) == pc_rtx
2577 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2578 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2583 /* Return 1 if X is an RTX that does nothing but set the condition codes
2584 and CLOBBER or USE registers.
2585 Return -1 if X does explicitly set the condition codes,
2586 but also does other things. */
2593 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
2595 if (GET_CODE (x) == PARALLEL)
2599 int other_things = 0;
2600 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2602 if (GET_CODE (XVECEXP (x, 0, i)) == SET
2603 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
2605 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
2608 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
2616 /* Follow any unconditional jump at LABEL;
2617 return the ultimate label reached by any such chain of jumps.
2618 If LABEL is not followed by a jump, return LABEL.
2619 If the chain loops or we can't find end, return LABEL,
2620 since that tells caller to avoid changing the insn.
2622 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
2623 a USE or CLOBBER. */
2626 follow_jumps (label)
2631 register rtx value = label;
2636 && (insn = next_active_insn (value)) != 0
2637 && GET_CODE (insn) == JUMP_INSN
2638 && (JUMP_LABEL (insn) != 0 || GET_CODE (PATTERN (insn)) == RETURN)
2639 && (next = NEXT_INSN (insn))
2640 && GET_CODE (next) == BARRIER);
2643 /* Don't chain through the insn that jumps into a loop
2644 from outside the loop,
2645 since that would create multiple loop entry jumps
2646 and prevent loop optimization. */
2648 if (!reload_completed)
2649 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
2650 if (GET_CODE (tem) == NOTE
2651 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
2654 /* If we have found a cycle, make the insn jump to itself. */
2655 if (JUMP_LABEL (insn) == label)
2657 value = JUMP_LABEL (insn);
2664 /* Assuming that field IDX of X is a vector of label_refs,
2665 replace each of them by the ultimate label reached by it.
2666 Return nonzero if a change is made.
2667 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
2670 tension_vector_labels (x, idx)
2676 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
2678 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
2679 register rtx nlabel = follow_jumps (olabel);
2680 if (nlabel && nlabel != olabel)
2682 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
2683 ++LABEL_NUSES (nlabel);
2684 if (--LABEL_NUSES (olabel) == 0)
2685 delete_insn (olabel);
2692 /* Find all CODE_LABELs referred to in X, and increment their use counts.
2693 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
2694 in INSN, then store one of them in JUMP_LABEL (INSN).
2695 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
2696 referenced in INSN, add a REG_LABEL note containing that label to INSN.
2697 Also, when there are consecutive labels, canonicalize on the last of them.
2699 Note that two labels separated by a loop-beginning note
2700 must be kept distinct if we have not yet done loop-optimization,
2701 because the gap between them is where loop-optimize
2702 will want to move invariant code to. CROSS_JUMP tells us
2703 that loop-optimization is done with.
2705 Once reload has completed (CROSS_JUMP non-zero), we need not consider
2706 two labels distinct if they are separated by only USE or CLOBBER insns. */
2709 mark_jump_label (x, insn, cross_jump)
2714 register RTX_CODE code = GET_CODE (x);
2732 /* If this is a constant-pool reference, see if it is a label. */
2733 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
2734 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
2735 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
2740 register rtx label = XEXP (x, 0);
2742 if (GET_CODE (label) != CODE_LABEL)
2744 /* Ignore references to labels of containing functions. */
2745 if (LABEL_REF_NONLOCAL_P (x))
2747 /* If there are other labels following this one,
2748 replace it with the last of the consecutive labels. */
2749 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
2751 if (GET_CODE (next) == CODE_LABEL)
2753 else if (cross_jump && GET_CODE (next) == INSN
2754 && (GET_CODE (PATTERN (next)) == USE
2755 || GET_CODE (PATTERN (next)) == CLOBBER))
2757 else if (GET_CODE (next) != NOTE)
2759 else if (! cross_jump
2760 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
2761 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
2764 XEXP (x, 0) = label;
2765 ++LABEL_NUSES (label);
2768 if (GET_CODE (insn) == JUMP_INSN)
2769 JUMP_LABEL (insn) = label;
2770 else if (! find_reg_note (insn, REG_LABEL, label))
2772 rtx next = next_real_insn (label);
2773 /* Don't record labels that refer to dispatch tables.
2774 This is not necessary, since the tablejump
2775 references the same label.
2776 And if we did record them, flow.c would make worse code. */
2778 || ! (GET_CODE (next) == JUMP_INSN
2779 && (GET_CODE (PATTERN (next)) == ADDR_VEC
2780 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
2781 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
2788 /* Do walk the labels in a vector, but not the first operand of an
2789 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
2793 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
2795 for (i = 0; i < XVECLEN (x, eltnum); i++)
2796 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
2801 fmt = GET_RTX_FORMAT (code);
2802 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2805 mark_jump_label (XEXP (x, i), insn, cross_jump);
2806 else if (fmt[i] == 'E')
2809 for (j = 0; j < XVECLEN (x, i); j++)
2810 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
2815 /* If all INSN does is set the pc, delete it,
2816 and delete the insn that set the condition codes for it
2817 if that's what the previous thing was. */
2823 register rtx x = PATTERN (insn);
2825 if (GET_CODE (x) == SET
2826 && GET_CODE (SET_DEST (x)) == PC)
2829 rtx prev = prev_nonnote_insn (insn);
2830 /* We assume that at this stage
2831 CC's are always set explicitly
2832 and always immediately before the jump that
2833 will use them. So if the previous insn
2834 exists to set the CC's, delete it
2835 (unless it performs auto-increments, etc.). */
2836 if (prev && GET_CODE (prev) == INSN
2837 && sets_cc0_p (PATTERN (prev)))
2839 if (sets_cc0_p (PATTERN (prev)) > 0
2840 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
2843 /* Otherwise, show that cc0 won't be used. */
2844 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
2845 cc0_rtx, REG_NOTES (prev));
2848 /* Now delete the jump insn itself. */
2849 delete_computation (insn);
2853 /* Delete INSN and recursively delete insns that compute values used only
2854 by INSN. This uses the REG_DEAD notes computed during flow analysis.
2855 If we are running before flow.c, we need do nothing since flow.c will
2856 delete dead code. We also can't know if the registers being used are
2857 dead or not at this point.
2859 Otherwise, look at all our REG_DEAD notes. If a previous insn does
2860 nothing other than set a register that dies in this insn, we can delete
2861 that insn as well. */
2864 delete_computation (insn)
2870 for (note = REG_NOTES (insn); note; note = next)
2874 next = XEXP (note, 1);
2876 if (REG_NOTE_KIND (note) != REG_DEAD
2877 /* Verify that the REG_NOTE is legitimate. */
2878 || GET_CODE (XEXP (note, 0)) != REG)
2881 for (our_prev = prev_nonnote_insn (insn);
2882 our_prev && GET_CODE (our_prev) == INSN;
2883 our_prev = prev_nonnote_insn (our_prev))
2885 /* If we reach a SEQUENCE, it is too complex to try to
2886 do anything with it, so give up. */
2887 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
2890 if (GET_CODE (PATTERN (our_prev)) == USE
2891 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
2892 /* reorg creates USEs that look like this. We leave them
2893 alone because reorg needs them for its own purposes. */
2896 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
2898 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
2901 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
2903 /* If we find a SET of something else, we can't
2908 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
2910 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
2912 if (GET_CODE (part) == SET
2913 && SET_DEST (part) != XEXP (note, 0))
2917 if (i == XVECLEN (PATTERN (our_prev), 0))
2918 delete_computation (our_prev);
2920 else if (GET_CODE (PATTERN (our_prev)) == SET
2921 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
2922 delete_computation (our_prev);
2927 /* If OUR_PREV references the register that dies here, it is an
2928 additional use. Hence any prior SET isn't dead. However, this
2929 insn becomes the new place for the REG_DEAD note. */
2930 if (reg_overlap_mentioned_p (XEXP (note, 0),
2931 PATTERN (our_prev)))
2933 XEXP (note, 1) = REG_NOTES (our_prev);
2934 REG_NOTES (our_prev) = note;
2939 #endif /* Don't HAVE_cc0 */
2943 /* Delete insn INSN from the chain of insns and update label ref counts.
2944 May delete some following insns as a consequence; may even delete
2945 a label elsewhere and insns that follow it.
2947 Returns the first insn after INSN that was not deleted. */
2953 register rtx next = NEXT_INSN (insn);
2954 register rtx prev = PREV_INSN (insn);
2955 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
2956 register int dont_really_delete = 0;
2958 while (next && INSN_DELETED_P (next))
2959 next = NEXT_INSN (next);
2961 /* This insn is already deleted => return first following nondeleted. */
2962 if (INSN_DELETED_P (insn))
2965 /* Don't delete user-declared labels. Convert them to special NOTEs
2967 if (was_code_label && LABEL_NAME (insn) != 0
2968 && optimize && ! dont_really_delete)
2970 PUT_CODE (insn, NOTE);
2971 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
2972 NOTE_SOURCE_FILE (insn) = 0;
2973 dont_really_delete = 1;
2976 /* Mark this insn as deleted. */
2977 INSN_DELETED_P (insn) = 1;
2979 /* If this is an unconditional jump, delete it from the jump chain. */
2980 if (simplejump_p (insn))
2981 delete_from_jump_chain (insn);
2983 /* If instruction is followed by a barrier,
2984 delete the barrier too. */
2986 if (next != 0 && GET_CODE (next) == BARRIER)
2988 INSN_DELETED_P (next) = 1;
2989 next = NEXT_INSN (next);
2992 /* Patch out INSN (and the barrier if any) */
2994 if (optimize && ! dont_really_delete)
2998 NEXT_INSN (prev) = next;
2999 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3000 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3001 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3006 PREV_INSN (next) = prev;
3007 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3008 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3011 if (prev && NEXT_INSN (prev) == 0)
3012 set_last_insn (prev);
3015 /* If deleting a jump, decrement the count of the label,
3016 and delete the label if it is now unused. */
3018 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3019 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3021 /* This can delete NEXT or PREV,
3022 either directly if NEXT is JUMP_LABEL (INSN),
3023 or indirectly through more levels of jumps. */
3024 delete_insn (JUMP_LABEL (insn));
3025 /* I feel a little doubtful about this loop,
3026 but I see no clean and sure alternative way
3027 to find the first insn after INSN that is not now deleted.
3028 I hope this works. */
3029 while (next && INSN_DELETED_P (next))
3030 next = NEXT_INSN (next);
3034 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3035 prev = PREV_INSN (prev);
3037 /* If INSN was a label and a dispatch table follows it,
3038 delete the dispatch table. The tablejump must have gone already.
3039 It isn't useful to fall through into a table. */
3042 && NEXT_INSN (insn) != 0
3043 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3044 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3045 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3046 next = delete_insn (NEXT_INSN (insn));
3048 /* If INSN was a label, delete insns following it if now unreachable. */
3050 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3052 register RTX_CODE code;
3054 && ((code = GET_CODE (next)) == INSN
3055 || code == JUMP_INSN || code == CALL_INSN
3057 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3060 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3061 next = NEXT_INSN (next);
3062 /* Keep going past other deleted labels to delete what follows. */
3063 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3064 next = NEXT_INSN (next);
3066 /* Note: if this deletes a jump, it can cause more
3067 deletion of unreachable code, after a different label.
3068 As long as the value from this recursive call is correct,
3069 this invocation functions correctly. */
3070 next = delete_insn (next);
3077 /* Advance from INSN till reaching something not deleted
3078 then return that. May return INSN itself. */
3081 next_nondeleted_insn (insn)
3084 while (INSN_DELETED_P (insn))
3085 insn = NEXT_INSN (insn);
3089 /* Delete a range of insns from FROM to TO, inclusive.
3090 This is for the sake of peephole optimization, so assume
3091 that whatever these insns do will still be done by a new
3092 peephole insn that will replace them. */
3095 delete_for_peephole (from, to)
3096 register rtx from, to;
3098 register rtx insn = from;
3102 register rtx next = NEXT_INSN (insn);
3103 register rtx prev = PREV_INSN (insn);
3105 if (GET_CODE (insn) != NOTE)
3107 INSN_DELETED_P (insn) = 1;
3109 /* Patch this insn out of the chain. */
3110 /* We don't do this all at once, because we
3111 must preserve all NOTEs. */
3113 NEXT_INSN (prev) = next;
3116 PREV_INSN (next) = prev;
3124 /* Note that if TO is an unconditional jump
3125 we *do not* delete the BARRIER that follows,
3126 since the peephole that replaces this sequence
3127 is also an unconditional jump in that case. */
3130 /* Invert the condition of the jump JUMP, and make it jump
3131 to label NLABEL instead of where it jumps now. */
3134 invert_jump (jump, nlabel)
3137 register rtx olabel = JUMP_LABEL (jump);
3139 /* We have to either invert the condition and change the label or
3140 do neither. Either operation could fail. We first try to invert
3141 the jump. If that succeeds, we try changing the label. If that fails,
3142 we invert the jump back to what it was. */
3144 if (! invert_exp (PATTERN (jump), jump))
3147 if (redirect_jump (jump, nlabel))
3150 if (! invert_exp (PATTERN (jump), jump))
3151 /* This should just be putting it back the way it was. */
3157 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3159 Return 1 if we can do so, 0 if we cannot find a way to do so that
3160 matches a pattern. */
3163 invert_exp (x, insn)
3167 register RTX_CODE code;
3171 code = GET_CODE (x);
3173 if (code == IF_THEN_ELSE)
3175 register rtx comp = XEXP (x, 0);
3178 /* We can do this in two ways: The preferable way, which can only
3179 be done if this is not an integer comparison, is to reverse
3180 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3181 of the IF_THEN_ELSE. If we can't do either, fail. */
3183 if (can_reverse_comparison_p (comp, insn)
3184 && validate_change (insn, &XEXP (x, 0),
3185 gen_rtx (reverse_condition (GET_CODE (comp)),
3186 GET_MODE (comp), XEXP (comp, 0),
3187 XEXP (comp, 1)), 0))
3191 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3192 validate_change (insn, &XEXP (x, 2), tem, 1);
3193 return apply_change_group ();
3196 fmt = GET_RTX_FORMAT (code);
3197 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3200 if (! invert_exp (XEXP (x, i), insn))
3205 for (j = 0; j < XVECLEN (x, i); j++)
3206 if (!invert_exp (XVECEXP (x, i, j), insn))
3214 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3215 If the old jump target label is unused as a result,
3216 it and the code following it may be deleted.
3218 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3221 The return value will be 1 if the change was made, 0 if it wasn't (this
3222 can only occur for NLABEL == 0). */
3225 redirect_jump (jump, nlabel)
3228 register rtx olabel = JUMP_LABEL (jump);
3230 if (nlabel == olabel)
3233 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3236 /* If this is an unconditional branch, delete it from the jump_chain of
3237 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3238 have UID's in range and JUMP_CHAIN is valid). */
3239 if (jump_chain && (simplejump_p (jump)
3240 || GET_CODE (PATTERN (jump)) == RETURN))
3242 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3244 delete_from_jump_chain (jump);
3245 if (label_index < max_jump_chain
3246 && INSN_UID (jump) < max_jump_chain)
3248 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3249 jump_chain[label_index] = jump;
3253 JUMP_LABEL (jump) = nlabel;
3255 ++LABEL_NUSES (nlabel);
3257 if (olabel && --LABEL_NUSES (olabel) == 0)
3258 delete_insn (olabel);
3263 /* Delete the instruction JUMP from any jump chain it might be on. */
3266 delete_from_jump_chain (jump)
3270 rtx olabel = JUMP_LABEL (jump);
3272 /* Handle unconditional jumps. */
3273 if (jump_chain && olabel != 0
3274 && INSN_UID (olabel) < max_jump_chain
3275 && simplejump_p (jump))
3276 index = INSN_UID (olabel);
3277 /* Handle return insns. */
3278 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3282 if (jump_chain[index] == jump)
3283 jump_chain[index] = jump_chain[INSN_UID (jump)];
3288 for (insn = jump_chain[index];
3290 insn = jump_chain[INSN_UID (insn)])
3291 if (jump_chain[INSN_UID (insn)] == jump)
3293 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3299 /* If NLABEL is nonzero, throughout the rtx at LOC,
3300 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3301 zero, alter (RETURN) to (LABEL_REF NLABEL).
3303 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3304 validity with validate_change. Convert (set (pc) (label_ref olabel))
3307 Return 0 if we found a change we would like to make but it is invalid.
3308 Otherwise, return 1. */
3311 redirect_exp (loc, olabel, nlabel, insn)
3316 register rtx x = *loc;
3317 register RTX_CODE code = GET_CODE (x);
3321 if (code == LABEL_REF)
3323 if (XEXP (x, 0) == olabel)
3326 XEXP (x, 0) = nlabel;
3328 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3332 else if (code == RETURN && olabel == 0)
3334 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3335 if (loc == &PATTERN (insn))
3336 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3337 return validate_change (insn, loc, x, 0);
3340 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3341 && GET_CODE (SET_SRC (x)) == LABEL_REF
3342 && XEXP (SET_SRC (x), 0) == olabel)
3343 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3345 fmt = GET_RTX_FORMAT (code);
3346 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3349 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3354 for (j = 0; j < XVECLEN (x, i); j++)
3355 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3363 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3365 If the old jump target label (before the dispatch table) becomes unused,
3366 it and the dispatch table may be deleted. In that case, find the insn
3367 before the jump references that label and delete it and logical successors
3371 redirect_tablejump (jump, nlabel)
3374 register rtx olabel = JUMP_LABEL (jump);
3376 /* Add this jump to the jump_chain of NLABEL. */
3377 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3378 && INSN_UID (jump) < max_jump_chain)
3380 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3381 jump_chain[INSN_UID (nlabel)] = jump;
3384 PATTERN (jump) = gen_jump (nlabel);
3385 JUMP_LABEL (jump) = nlabel;
3386 ++LABEL_NUSES (nlabel);
3387 INSN_CODE (jump) = -1;
3389 if (--LABEL_NUSES (olabel) == 0)
3391 delete_labelref_insn (jump, olabel, 0);
3392 delete_insn (olabel);
3396 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3397 If we found one, delete it and then delete this insn if DELETE_THIS is
3398 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3401 delete_labelref_insn (insn, label, delete_this)
3408 if (GET_CODE (insn) != NOTE
3409 && reg_mentioned_p (label, PATTERN (insn)))
3420 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3421 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3435 /* Like rtx_equal_p except that it considers two REGs as equal
3436 if they renumber to the same value. */
3439 rtx_renumbered_equal_p (x, y)
3443 register RTX_CODE code = GET_CODE (x);
3448 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3449 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3450 && GET_CODE (SUBREG_REG (y)) == REG)))
3454 if (GET_MODE (x) != GET_MODE (y))
3457 /* If we haven't done any renumbering, don't
3458 make any assumptions. */
3459 if (reg_renumber == 0)
3460 return rtx_equal_p (x, y);
3464 i = REGNO (SUBREG_REG (x));
3465 if (reg_renumber[i] >= 0)
3466 i = reg_renumber[i];
3467 i += SUBREG_WORD (x);
3472 if (reg_renumber[i] >= 0)
3473 i = reg_renumber[i];
3475 if (GET_CODE (y) == SUBREG)
3477 j = REGNO (SUBREG_REG (y));
3478 if (reg_renumber[j] >= 0)
3479 j = reg_renumber[j];
3480 j += SUBREG_WORD (y);
3485 if (reg_renumber[j] >= 0)
3486 j = reg_renumber[j];
3490 /* Now we have disposed of all the cases
3491 in which different rtx codes can match. */
3492 if (code != GET_CODE (y))
3503 return XINT (x, 0) == XINT (y, 0);
3506 /* We can't assume nonlocal labels have their following insns yet. */
3507 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3508 return XEXP (x, 0) == XEXP (y, 0);
3509 /* Two label-refs are equivalent if they point at labels
3510 in the same position in the instruction stream. */
3511 return (next_real_insn (XEXP (x, 0))
3512 == next_real_insn (XEXP (y, 0)));
3515 return XSTR (x, 0) == XSTR (y, 0);
3518 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3520 if (GET_MODE (x) != GET_MODE (y))
3523 /* Compare the elements. If any pair of corresponding elements
3524 fail to match, return 0 for the whole things. */
3526 fmt = GET_RTX_FORMAT (code);
3527 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3533 if (XWINT (x, i) != XWINT (y, i))
3538 if (XINT (x, i) != XINT (y, i))
3543 if (strcmp (XSTR (x, i), XSTR (y, i)))
3548 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
3553 if (XEXP (x, i) != XEXP (y, i))
3560 if (XVECLEN (x, i) != XVECLEN (y, i))
3562 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3563 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
3574 /* If X is a hard register or equivalent to one or a subregister of one,
3575 return the hard register number. If X is a pseudo register that was not
3576 assigned a hard register, return the pseudo register number. Otherwise,
3577 return -1. Any rtx is valid for X. */
3583 if (GET_CODE (x) == REG)
3585 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
3586 return reg_renumber[REGNO (x)];
3589 if (GET_CODE (x) == SUBREG)
3591 int base = true_regnum (SUBREG_REG (x));
3592 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
3593 return SUBREG_WORD (x) + base;
3598 /* Optimize code of the form:
3600 for (x = a[i]; x; ...)
3602 for (x = a[i]; x; ...)
3606 Loop optimize will change the above code into
3610 { ...; if (! (x = ...)) break; }
3613 { ...; if (! (x = ...)) break; }
3616 In general, if the first test fails, the program can branch
3617 directly to `foo' and skip the second try which is doomed to fail.
3618 We run this after loop optimization and before flow analysis. */
3620 /* When comparing the insn patterns, we track the fact that different
3621 pseudo-register numbers may have been used in each computation.
3622 The following array stores an equivalence -- same_regs[I] == J means
3623 that pseudo register I was used in the first set of tests in a context
3624 where J was used in the second set. We also count the number of such
3625 pending equivalences. If nonzero, the expressions really aren't the
3628 static short *same_regs;
3630 static int num_same_regs;
3632 /* Track any registers modified between the target of the first jump and
3633 the second jump. They never compare equal. */
3635 static char *modified_regs;
3637 /* Record if memory was modified. */
3639 static int modified_mem;
3641 /* Called via note_stores on each insn between the target of the first
3642 branch and the second branch. It marks any changed registers. */
3645 mark_modified_reg (dest, x)
3651 if (GET_CODE (dest) == SUBREG)
3652 dest = SUBREG_REG (dest);
3654 if (GET_CODE (dest) == MEM)
3657 if (GET_CODE (dest) != REG)
3660 regno = REGNO (dest);
3661 if (regno >= FIRST_PSEUDO_REGISTER)
3662 modified_regs[regno] = 1;
3664 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
3665 modified_regs[regno + i] = 1;
3668 /* F is the first insn in the chain of insns. */
3671 thread_jumps (f, max_reg, verbose)
3676 /* Basic algorithm is to find a conditional branch,
3677 the label it may branch to, and the branch after
3678 that label. If the two branches test the same condition,
3679 walk back from both branch paths until the insn patterns
3680 differ, or code labels are hit. If we make it back to
3681 the target of the first branch, then we know that the first branch
3682 will either always succeed or always fail depending on the relative
3683 senses of the two branches. So adjust the first branch accordingly
3686 rtx label, b1, b2, t1, t2;
3687 enum rtx_code code1, code2;
3688 rtx b1op0, b1op1, b2op0, b2op1;
3693 /* Allocate register tables and quick-reset table. */
3694 modified_regs = (char *) alloca (max_reg * sizeof (char));
3695 same_regs = (short *) alloca (max_reg * sizeof (short));
3696 all_reset = (short *) alloca (max_reg * sizeof (short));
3697 for (i = 0; i < max_reg; i++)
3704 for (b1 = f; b1; b1 = NEXT_INSN (b1))
3706 /* Get to a candidate branch insn. */
3707 if (GET_CODE (b1) != JUMP_INSN
3708 || ! condjump_p (b1) || simplejump_p (b1)
3709 || JUMP_LABEL (b1) == 0)
3712 bzero (modified_regs, max_reg * sizeof (char));
3715 bcopy (all_reset, same_regs, max_reg * sizeof (short));
3718 label = JUMP_LABEL (b1);
3720 /* Look for a branch after the target. Record any registers and
3721 memory modified between the target and the branch. Stop when we
3722 get to a label since we can't know what was changed there. */
3723 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
3725 if (GET_CODE (b2) == CODE_LABEL)
3728 else if (GET_CODE (b2) == JUMP_INSN)
3730 /* If this is an unconditional jump and is the only use of
3731 its target label, we can follow it. */
3732 if (simplejump_p (b2)
3733 && JUMP_LABEL (b2) != 0
3734 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
3736 b2 = JUMP_LABEL (b2);
3743 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
3746 if (GET_CODE (b2) == CALL_INSN)
3749 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3750 if (call_used_regs[i] && ! fixed_regs[i]
3751 && i != STACK_POINTER_REGNUM
3752 && i != FRAME_POINTER_REGNUM
3753 && i != ARG_POINTER_REGNUM)
3754 modified_regs[i] = 1;
3757 note_stores (PATTERN (b2), mark_modified_reg);
3760 /* Check the next candidate branch insn from the label
3763 || GET_CODE (b2) != JUMP_INSN
3765 || ! condjump_p (b2)
3766 || simplejump_p (b2))
3769 /* Get the comparison codes and operands, reversing the
3770 codes if appropriate. If we don't have comparison codes,
3771 we can't do anything. */
3772 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
3773 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
3774 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
3775 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
3776 code1 = reverse_condition (code1);
3778 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
3779 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
3780 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
3781 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
3782 code2 = reverse_condition (code2);
3784 /* If they test the same things and knowing that B1 branches
3785 tells us whether or not B2 branches, check if we
3786 can thread the branch. */
3787 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
3788 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
3789 && (comparison_dominates_p (code1, code2)
3790 || comparison_dominates_p (code1, reverse_condition (code2))))
3792 t1 = prev_nonnote_insn (b1);
3793 t2 = prev_nonnote_insn (b2);
3795 while (t1 != 0 && t2 != 0)
3797 if (t1 == 0 || t2 == 0)
3802 /* We have reached the target of the first branch.
3803 If there are no pending register equivalents,
3804 we know that this branch will either always
3805 succeed (if the senses of the two branches are
3806 the same) or always fail (if not). */
3809 if (num_same_regs != 0)
3812 if (comparison_dominates_p (code1, code2))
3813 new_label = JUMP_LABEL (b2);
3815 new_label = get_label_after (b2);
3817 if (JUMP_LABEL (b1) != new_label
3818 && redirect_jump (b1, new_label))
3823 /* If either of these is not a normal insn (it might be
3824 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
3825 have already been skipped above.) Similarly, fail
3826 if the insns are different. */
3827 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
3828 || recog_memoized (t1) != recog_memoized (t2)
3829 || ! rtx_equal_for_thread_p (PATTERN (t1),
3833 t1 = prev_nonnote_insn (t1);
3834 t2 = prev_nonnote_insn (t2);
3841 /* This is like RTX_EQUAL_P except that it knows about our handling of
3842 possibly equivalent registers and knows to consider volatile and
3843 modified objects as not equal.
3845 YINSN is the insn containing Y. */
3848 rtx_equal_for_thread_p (x, y, yinsn)
3854 register enum rtx_code code;
3857 code = GET_CODE (x);
3858 /* Rtx's of different codes cannot be equal. */
3859 if (code != GET_CODE (y))
3862 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
3863 (REG:SI x) and (REG:HI x) are NOT equivalent. */
3865 if (GET_MODE (x) != GET_MODE (y))
3868 /* Handle special-cases first. */
3872 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
3875 /* If neither is user variable or hard register, check for possible
3877 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
3878 || REGNO (x) < FIRST_PSEUDO_REGISTER
3879 || REGNO (y) < FIRST_PSEUDO_REGISTER)
3882 if (same_regs[REGNO (x)] == -1)
3884 same_regs[REGNO (x)] = REGNO (y);
3887 /* If this is the first time we are seeing a register on the `Y'
3888 side, see if it is the last use. If not, we can't thread the
3889 jump, so mark it as not equivalent. */
3890 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
3896 return (same_regs[REGNO (x)] == REGNO (y));
3901 /* If memory modified or either volatile, not equivalent.
3902 Else, check address. */
3903 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
3906 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
3909 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
3915 /* Cancel a pending `same_regs' if setting equivalenced registers.
3916 Then process source. */
3917 if (GET_CODE (SET_DEST (x)) == REG
3918 && GET_CODE (SET_DEST (y)) == REG)
3920 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
3922 same_regs[REGNO (SET_DEST (x))] = -1;
3925 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
3929 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
3932 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
3935 return XEXP (x, 0) == XEXP (y, 0);
3938 return XSTR (x, 0) == XSTR (y, 0);
3944 fmt = GET_RTX_FORMAT (code);
3945 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3950 if (XWINT (x, i) != XWINT (y, i))
3956 if (XINT (x, i) != XINT (y, i))
3962 /* Two vectors must have the same length. */
3963 if (XVECLEN (x, i) != XVECLEN (y, i))
3966 /* And the corresponding elements must match. */
3967 for (j = 0; j < XVECLEN (x, i); j++)
3968 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
3969 XVECEXP (y, i, j), yinsn) == 0)
3974 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
3980 if (strcmp (XSTR (x, i), XSTR (y, i)))
3985 /* These are just backpointers, so they don't matter. */
3991 /* It is believed that rtx's at this level will never
3992 contain anything but integers and other rtx's,
3993 except for within LABEL_REFs and SYMBOL_REFs. */