1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-97, 1998 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This is the jump-optimization pass of the compiler.
23 It is run two or three times: once before cse, sometimes once after cse,
24 and once after reload (before final).
26 jump_optimize deletes unreachable code and labels that are not used.
27 It also deletes jumps that jump to the following insn,
28 and simplifies jumps around unconditional jumps and jumps
29 to unconditional jumps.
31 Each CODE_LABEL has a count of the times it is used
32 stored in the LABEL_NUSES internal field, and each JUMP_INSN
33 has one label that it refers to stored in the
34 JUMP_LABEL internal field. With this we can detect labels that
35 become unused because of the deletion of all the jumps that
36 formerly used them. The JUMP_LABEL info is sometimes looked
39 Optionally, cross-jumping can be done. Currently it is done
40 only the last time (when after reload and before final).
41 In fact, the code for cross-jumping now assumes that register
42 allocation has been done, since it uses `rtx_renumbered_equal_p'.
44 Jump optimization is done after cse when cse's constant-propagation
45 causes jumps to become unconditional or to be deleted.
47 Unreachable loops are not detected here, because the labels
48 have references and the insns appear reachable from the labels.
49 find_basic_blocks in flow.c finds and deletes such loops.
51 The subroutines delete_insn, redirect_jump, and invert_jump are used
52 from other passes as well. */
58 #include "hard-reg-set.h"
60 #include "insn-config.h"
61 #include "insn-flags.h"
67 /* ??? Eventually must record somehow the labels used by jumps
68 from nested functions. */
69 /* Pre-record the next or previous real insn for each label?
70 No, this pass is very fast anyway. */
71 /* Condense consecutive labels?
72 This would make life analysis faster, maybe. */
73 /* Optimize jump y; x: ... y: jumpif... x?
74 Don't know if it is worth bothering with. */
75 /* Optimize two cases of conditional jump to conditional jump?
76 This can never delete any instruction or make anything dead,
77 or even change what is live at any point.
78 So perhaps let combiner do it. */
80 /* Vector indexed by uid.
81 For each CODE_LABEL, index by its uid to get first unconditional jump
82 that jumps to the label.
83 For each JUMP_INSN, index by its uid to get the next unconditional jump
84 that jumps to the same label.
85 Element 0 is the start of a chain of all return insns.
86 (It is safe to use element 0 because insn uid 0 is not used. */
88 static rtx *jump_chain;
90 /* List of labels referred to from initializers.
91 These can never be deleted. */
94 /* Maximum index in jump_chain. */
96 static int max_jump_chain;
98 /* Set nonzero by jump_optimize if control can fall through
99 to the end of the function. */
102 /* Indicates whether death notes are significant in cross jump analysis.
103 Normally they are not significant, because of A and B jump to C,
104 and R dies in A, it must die in B. But this might not be true after
105 stack register conversion, and we must compare death notes in that
108 static int cross_jump_death_matters = 0;
110 static int duplicate_loop_exit_test PROTO((rtx));
111 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
112 static void do_cross_jump PROTO((rtx, rtx, rtx));
113 static int jump_back_p PROTO((rtx, rtx));
114 static int tension_vector_labels PROTO((rtx, int));
115 static void mark_jump_label PROTO((rtx, rtx, int));
116 static void delete_computation PROTO((rtx));
117 static void delete_from_jump_chain PROTO((rtx));
118 static int delete_labelref_insn PROTO((rtx, rtx, int));
119 static void mark_modified_reg PROTO((rtx, rtx));
120 static void redirect_tablejump PROTO((rtx, rtx));
121 static rtx find_insert_position PROTO((rtx, rtx));
123 /* Delete no-op jumps and optimize jumps to jumps
124 and jumps around jumps.
125 Delete unused labels and unreachable code.
127 If CROSS_JUMP is 1, detect matching code
128 before a jump and its destination and unify them.
129 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
131 If NOOP_MOVES is nonzero, delete no-op move insns.
133 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
134 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
136 If `optimize' is zero, don't change any code,
137 just determine whether control drops off the end of the function.
138 This case occurs when we have -W and not -O.
139 It works because `delete_insn' checks the value of `optimize'
140 and refrains from actually deleting when that is 0. */
143 jump_optimize (f, cross_jump, noop_moves, after_regscan)
149 register rtx insn, next, note;
155 cross_jump_death_matters = (cross_jump == 2);
157 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
158 notes whose labels don't occur in the insn any more. */
160 for (insn = f; insn; insn = NEXT_INSN (insn))
162 if (GET_CODE (insn) == CODE_LABEL)
163 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
164 else if (GET_CODE (insn) == JUMP_INSN)
165 JUMP_LABEL (insn) = 0;
166 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
167 for (note = REG_NOTES (insn); note; note = next)
169 next = XEXP (note, 1);
170 if (REG_NOTE_KIND (note) == REG_LABEL
171 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
172 remove_note (insn, note);
175 if (INSN_UID (insn) > max_uid)
176 max_uid = INSN_UID (insn);
181 /* Delete insns following barriers, up to next label. */
183 for (insn = f; insn;)
185 if (GET_CODE (insn) == BARRIER)
187 insn = NEXT_INSN (insn);
188 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
190 if (GET_CODE (insn) == NOTE
191 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
192 insn = NEXT_INSN (insn);
194 insn = delete_insn (insn);
196 /* INSN is now the code_label. */
199 insn = NEXT_INSN (insn);
202 /* Leave some extra room for labels and duplicate exit test insns
204 max_jump_chain = max_uid * 14 / 10;
205 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
206 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
208 /* Mark the label each jump jumps to.
209 Combine consecutive labels, and count uses of labels.
211 For each label, make a chain (using `jump_chain')
212 of all the *unconditional* jumps that jump to it;
213 also make a chain of all returns. */
215 for (insn = f; insn; insn = NEXT_INSN (insn))
216 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
218 mark_jump_label (PATTERN (insn), insn, cross_jump);
219 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
221 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
223 jump_chain[INSN_UID (insn)]
224 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
225 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
227 if (GET_CODE (PATTERN (insn)) == RETURN)
229 jump_chain[INSN_UID (insn)] = jump_chain[0];
230 jump_chain[0] = insn;
235 /* Keep track of labels used from static data;
236 they cannot ever be deleted. */
238 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
239 LABEL_NUSES (XEXP (insn, 0))++;
241 check_exception_handler_labels ();
243 /* Keep track of labels used for marking handlers for exception
244 regions; they cannot usually be deleted. */
246 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
247 LABEL_NUSES (XEXP (insn, 0))++;
249 exception_optimize ();
251 /* Delete all labels already not referenced.
252 Also find the last insn. */
255 for (insn = f; insn; )
257 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
258 insn = delete_insn (insn);
262 insn = NEXT_INSN (insn);
268 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
269 If so record that this function can drop off the end. */
275 /* One label can follow the end-note: the return label. */
276 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
277 /* Ordinary insns can follow it if returning a structure. */
278 || GET_CODE (insn) == INSN
279 /* If machine uses explicit RETURN insns, no epilogue,
280 then one of them follows the note. */
281 || (GET_CODE (insn) == JUMP_INSN
282 && GET_CODE (PATTERN (insn)) == RETURN)
283 /* A barrier can follow the return insn. */
284 || GET_CODE (insn) == BARRIER
285 /* Other kinds of notes can follow also. */
286 || (GET_CODE (insn) == NOTE
287 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
288 insn = PREV_INSN (insn);
291 /* Report if control can fall through at the end of the function. */
292 if (insn && GET_CODE (insn) == NOTE
293 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
294 && ! INSN_DELETED_P (insn))
297 /* Zero the "deleted" flag of all the "deleted" insns. */
298 for (insn = f; insn; insn = NEXT_INSN (insn))
299 INSN_DELETED_P (insn) = 0;
306 /* If we fall through to the epilogue, see if we can insert a RETURN insn
307 in front of it. If the machine allows it at this point (we might be
308 after reload for a leaf routine), it will improve optimization for it
310 insn = get_last_insn ();
311 while (insn && GET_CODE (insn) == NOTE)
312 insn = PREV_INSN (insn);
314 if (insn && GET_CODE (insn) != BARRIER)
316 emit_jump_insn (gen_return ());
323 for (insn = f; insn; )
325 next = NEXT_INSN (insn);
327 if (GET_CODE (insn) == INSN)
329 register rtx body = PATTERN (insn);
331 /* Combine stack_adjusts with following push_insns. */
333 if (GET_CODE (body) == SET
334 && SET_DEST (body) == stack_pointer_rtx
335 && GET_CODE (SET_SRC (body)) == PLUS
336 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
337 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
338 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
341 rtx stack_adjust_insn = insn;
342 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
343 int total_pushed = 0;
346 /* Find all successive push insns. */
348 /* Don't convert more than three pushes;
349 that starts adding too many displaced addresses
350 and the whole thing starts becoming a losing
355 p = next_nonnote_insn (p);
356 if (p == 0 || GET_CODE (p) != INSN)
359 if (GET_CODE (pbody) != SET)
361 dest = SET_DEST (pbody);
362 /* Allow a no-op move between the adjust and the push. */
363 if (GET_CODE (dest) == REG
364 && GET_CODE (SET_SRC (pbody)) == REG
365 && REGNO (dest) == REGNO (SET_SRC (pbody)))
367 if (! (GET_CODE (dest) == MEM
368 && GET_CODE (XEXP (dest, 0)) == POST_INC
369 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
372 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
373 > stack_adjust_amount)
375 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
378 /* Discard the amount pushed from the stack adjust;
379 maybe eliminate it entirely. */
380 if (total_pushed >= stack_adjust_amount)
382 delete_computation (stack_adjust_insn);
383 total_pushed = stack_adjust_amount;
386 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
387 = GEN_INT (stack_adjust_amount - total_pushed);
389 /* Change the appropriate push insns to ordinary stores. */
391 while (total_pushed > 0)
394 p = next_nonnote_insn (p);
395 if (GET_CODE (p) != INSN)
398 if (GET_CODE (pbody) == SET)
400 dest = SET_DEST (pbody);
401 if (! (GET_CODE (dest) == MEM
402 && GET_CODE (XEXP (dest, 0)) == POST_INC
403 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
405 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
406 /* If this push doesn't fully fit in the space
407 of the stack adjust that we deleted,
408 make another stack adjust here for what we
409 didn't use up. There should be peepholes
410 to recognize the resulting sequence of insns. */
411 if (total_pushed < 0)
413 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
414 GEN_INT (- total_pushed)),
419 = plus_constant (stack_pointer_rtx, total_pushed);
424 /* Detect and delete no-op move instructions
425 resulting from not allocating a parameter in a register. */
427 if (GET_CODE (body) == SET
428 && (SET_DEST (body) == SET_SRC (body)
429 || (GET_CODE (SET_DEST (body)) == MEM
430 && GET_CODE (SET_SRC (body)) == MEM
431 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
432 && ! (GET_CODE (SET_DEST (body)) == MEM
433 && MEM_VOLATILE_P (SET_DEST (body)))
434 && ! (GET_CODE (SET_SRC (body)) == MEM
435 && MEM_VOLATILE_P (SET_SRC (body))))
436 delete_computation (insn);
438 /* Detect and ignore no-op move instructions
439 resulting from smart or fortuitous register allocation. */
441 else if (GET_CODE (body) == SET)
443 int sreg = true_regnum (SET_SRC (body));
444 int dreg = true_regnum (SET_DEST (body));
446 if (sreg == dreg && sreg >= 0)
448 else if (sreg >= 0 && dreg >= 0)
451 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
452 sreg, NULL_PTR, dreg,
453 GET_MODE (SET_SRC (body)));
456 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
458 /* DREG may have been the target of a REG_DEAD note in
459 the insn which makes INSN redundant. If so, reorg
460 would still think it is dead. So search for such a
461 note and delete it if we find it. */
462 if (! find_regno_note (insn, REG_UNUSED, dreg))
463 for (trial = prev_nonnote_insn (insn);
464 trial && GET_CODE (trial) != CODE_LABEL;
465 trial = prev_nonnote_insn (trial))
466 if (find_regno_note (trial, REG_DEAD, dreg))
468 remove_death (dreg, trial);
471 #ifdef PRESERVE_DEATH_INFO_REGNO_P
472 /* Deleting insn could lose a death-note for SREG
473 so don't do it if final needs accurate
475 if (PRESERVE_DEATH_INFO_REGNO_P (sreg)
476 && (trial = find_regno_note (insn, REG_DEAD, sreg)))
478 /* Change this into a USE so that we won't emit
479 code for it, but still can keep the note. */
481 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
482 INSN_CODE (insn) = -1;
483 /* Remove all reg notes but the REG_DEAD one. */
484 REG_NOTES (insn) = trial;
485 XEXP (trial, 1) = NULL_RTX;
492 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
493 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
495 GET_MODE (SET_DEST (body))))
497 /* This handles the case where we have two consecutive
498 assignments of the same constant to pseudos that didn't
499 get a hard reg. Each SET from the constant will be
500 converted into a SET of the spill register and an
501 output reload will be made following it. This produces
502 two loads of the same constant into the same spill
507 /* Look back for a death note for the first reg.
508 If there is one, it is no longer accurate. */
509 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
511 if ((GET_CODE (in_insn) == INSN
512 || GET_CODE (in_insn) == JUMP_INSN)
513 && find_regno_note (in_insn, REG_DEAD, dreg))
515 remove_death (dreg, in_insn);
518 in_insn = PREV_INSN (in_insn);
521 /* Delete the second load of the value. */
525 else if (GET_CODE (body) == PARALLEL)
527 /* If each part is a set between two identical registers or
528 a USE or CLOBBER, delete the insn. */
532 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
534 tem = XVECEXP (body, 0, i);
535 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
538 if (GET_CODE (tem) != SET
539 || (sreg = true_regnum (SET_SRC (tem))) < 0
540 || (dreg = true_regnum (SET_DEST (tem))) < 0
548 /* Also delete insns to store bit fields if they are no-ops. */
549 /* Not worth the hair to detect this in the big-endian case. */
550 else if (! BYTES_BIG_ENDIAN
551 && GET_CODE (body) == SET
552 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
553 && XEXP (SET_DEST (body), 2) == const0_rtx
554 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
555 && ! (GET_CODE (SET_SRC (body)) == MEM
556 && MEM_VOLATILE_P (SET_SRC (body))))
562 /* If we haven't yet gotten to reload and we have just run regscan,
563 delete any insn that sets a register that isn't used elsewhere.
564 This helps some of the optimizations below by having less insns
565 being jumped around. */
567 if (! reload_completed && after_regscan)
568 for (insn = f; insn; insn = next)
570 rtx set = single_set (insn);
572 next = NEXT_INSN (insn);
574 if (set && GET_CODE (SET_DEST (set)) == REG
575 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
576 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
577 /* We use regno_last_note_uid so as not to delete the setting
578 of a reg that's used in notes. A subsequent optimization
579 might arrange to use that reg for real. */
580 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
581 && ! side_effects_p (SET_SRC (set))
582 && ! find_reg_note (insn, REG_RETVAL, 0))
586 /* Now iterate optimizing jumps until nothing changes over one pass. */
592 for (insn = f; insn; insn = next)
595 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
597 int this_is_simplejump, this_is_condjump, reversep;
598 int this_is_condjump_in_parallel;
600 /* If NOT the first iteration, if this is the last jump pass
601 (just before final), do the special peephole optimizations.
602 Avoiding the first iteration gives ordinary jump opts
603 a chance to work before peephole opts. */
605 if (reload_completed && !first && !flag_no_peephole)
606 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
610 /* That could have deleted some insns after INSN, so check now
611 what the following insn is. */
613 next = NEXT_INSN (insn);
615 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
616 jump. Try to optimize by duplicating the loop exit test if so.
617 This is only safe immediately after regscan, because it uses
618 the values of regno_first_uid and regno_last_uid. */
619 if (after_regscan && GET_CODE (insn) == NOTE
620 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
621 && (temp1 = next_nonnote_insn (insn)) != 0
622 && simplejump_p (temp1))
624 temp = PREV_INSN (insn);
625 if (duplicate_loop_exit_test (insn))
628 next = NEXT_INSN (temp);
633 if (GET_CODE (insn) != JUMP_INSN)
636 this_is_simplejump = simplejump_p (insn);
637 this_is_condjump = condjump_p (insn);
638 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
640 /* Tension the labels in dispatch tables. */
642 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
643 changed |= tension_vector_labels (PATTERN (insn), 0);
644 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
645 changed |= tension_vector_labels (PATTERN (insn), 1);
647 /* If a dispatch table always goes to the same place,
648 get rid of it and replace the insn that uses it. */
650 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
651 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
654 rtx pat = PATTERN (insn);
655 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
656 int len = XVECLEN (pat, diff_vec_p);
657 rtx dispatch = prev_real_insn (insn);
659 for (i = 0; i < len; i++)
660 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
661 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
665 && GET_CODE (dispatch) == JUMP_INSN
666 && JUMP_LABEL (dispatch) != 0
667 /* Don't mess with a casesi insn. */
668 && !(GET_CODE (PATTERN (dispatch)) == SET
669 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
671 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
673 redirect_tablejump (dispatch,
674 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
679 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
681 /* If a jump references the end of the function, try to turn
682 it into a RETURN insn, possibly a conditional one. */
683 if (JUMP_LABEL (insn)
684 && (next_active_insn (JUMP_LABEL (insn)) == 0
685 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
687 changed |= redirect_jump (insn, NULL_RTX);
689 /* Detect jump to following insn. */
690 if (reallabelprev == insn && condjump_p (insn))
692 next = next_real_insn (JUMP_LABEL (insn));
698 /* If we have an unconditional jump preceded by a USE, try to put
699 the USE before the target and jump there. This simplifies many
700 of the optimizations below since we don't have to worry about
701 dealing with these USE insns. We only do this if the label
702 being branch to already has the identical USE or if code
703 never falls through to that label. */
705 if (this_is_simplejump
706 && (temp = prev_nonnote_insn (insn)) != 0
707 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
708 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
709 && (GET_CODE (temp1) == BARRIER
710 || (GET_CODE (temp1) == INSN
711 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
712 /* Don't do this optimization if we have a loop containing only
713 the USE instruction, and the loop start label has a usage
714 count of 1. This is because we will redo this optimization
715 everytime through the outer loop, and jump opt will never
717 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
718 && temp2 == JUMP_LABEL (insn)
719 && LABEL_NUSES (temp2) == 1))
721 if (GET_CODE (temp1) == BARRIER)
723 emit_insn_after (PATTERN (temp), temp1);
724 temp1 = NEXT_INSN (temp1);
728 redirect_jump (insn, get_label_before (temp1));
729 reallabelprev = prev_real_insn (temp1);
733 /* Simplify if (...) x = a; else x = b; by converting it
734 to x = b; if (...) x = a;
735 if B is sufficiently simple, the test doesn't involve X,
736 and nothing in the test modifies B or X.
738 If we have small register classes, we also can't do this if X
741 If the "x = b;" insn has any REG_NOTES, we don't do this because
742 of the possibility that we are running after CSE and there is a
743 REG_EQUAL note that is only valid if the branch has already been
744 taken. If we move the insn with the REG_EQUAL note, we may
745 fold the comparison to always be false in a later CSE pass.
746 (We could also delete the REG_NOTES when moving the insn, but it
747 seems simpler to not move it.) An exception is that we can move
748 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
749 value is the same as "b".
751 INSN is the branch over the `else' part.
755 TEMP to the jump insn preceding "x = a;"
757 TEMP2 to the insn that sets "x = b;"
758 TEMP3 to the insn that sets "x = a;"
759 TEMP4 to the set of "x = b"; */
761 if (this_is_simplejump
762 && (temp3 = prev_active_insn (insn)) != 0
763 && GET_CODE (temp3) == INSN
764 && (temp4 = single_set (temp3)) != 0
765 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
766 && (! SMALL_REGISTER_CLASSES
767 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
768 && (temp2 = next_active_insn (insn)) != 0
769 && GET_CODE (temp2) == INSN
770 && (temp4 = single_set (temp2)) != 0
771 && rtx_equal_p (SET_DEST (temp4), temp1)
772 && (GET_CODE (SET_SRC (temp4)) == REG
773 || GET_CODE (SET_SRC (temp4)) == SUBREG
774 || (GET_CODE (SET_SRC (temp4)) == MEM
775 && RTX_UNCHANGING_P (SET_SRC (temp4)))
776 || CONSTANT_P (SET_SRC (temp4)))
777 && (REG_NOTES (temp2) == 0
778 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
779 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
780 && XEXP (REG_NOTES (temp2), 1) == 0
781 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
783 && (temp = prev_active_insn (temp3)) != 0
784 && condjump_p (temp) && ! simplejump_p (temp)
785 /* TEMP must skip over the "x = a;" insn */
786 && prev_real_insn (JUMP_LABEL (temp)) == insn
787 && no_labels_between_p (insn, JUMP_LABEL (temp))
788 /* There must be no other entries to the "x = b;" insn. */
789 && no_labels_between_p (JUMP_LABEL (temp), temp2)
790 /* INSN must either branch to the insn after TEMP2 or the insn
791 after TEMP2 must branch to the same place as INSN. */
792 && (reallabelprev == temp2
793 || ((temp5 = next_active_insn (temp2)) != 0
794 && simplejump_p (temp5)
795 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
797 /* The test expression, X, may be a complicated test with
798 multiple branches. See if we can find all the uses of
799 the label that TEMP branches to without hitting a CALL_INSN
800 or a jump to somewhere else. */
801 rtx target = JUMP_LABEL (temp);
802 int nuses = LABEL_NUSES (target);
808 /* Set P to the first jump insn that goes around "x = a;". */
809 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
811 if (GET_CODE (p) == JUMP_INSN)
813 if (condjump_p (p) && ! simplejump_p (p)
814 && JUMP_LABEL (p) == target)
823 else if (GET_CODE (p) == CALL_INSN)
828 /* We cannot insert anything between a set of cc and its use
829 so if P uses cc0, we must back up to the previous insn. */
830 q = prev_nonnote_insn (p);
831 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
832 && sets_cc0_p (PATTERN (q)))
839 /* If we found all the uses and there was no data conflict, we
840 can move the assignment unless we can branch into the middle
843 && no_labels_between_p (p, insn)
844 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
845 && ! reg_set_between_p (temp1, p, temp3)
846 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
847 || ! reg_set_between_p (SET_SRC (temp4), p, temp2)))
849 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
852 /* Set NEXT to an insn that we know won't go away. */
853 next = next_active_insn (insn);
855 /* Delete the jump around the set. Note that we must do
856 this before we redirect the test jumps so that it won't
857 delete the code immediately following the assignment
858 we moved (which might be a jump). */
862 /* We either have two consecutive labels or a jump to
863 a jump, so adjust all the JUMP_INSNs to branch to where
865 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
866 if (GET_CODE (p) == JUMP_INSN)
867 redirect_jump (p, target);
874 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
875 to x = a; if (...) goto l; x = b;
876 if A is sufficiently simple, the test doesn't involve X,
877 and nothing in the test modifies A or X.
879 If we have small register classes, we also can't do this if X
882 If the "x = a;" insn has any REG_NOTES, we don't do this because
883 of the possibility that we are running after CSE and there is a
884 REG_EQUAL note that is only valid if the branch has already been
885 taken. If we move the insn with the REG_EQUAL note, we may
886 fold the comparison to always be false in a later CSE pass.
887 (We could also delete the REG_NOTES when moving the insn, but it
888 seems simpler to not move it.) An exception is that we can move
889 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
890 value is the same as "a".
896 TEMP to the jump insn preceding "x = a;"
898 TEMP2 to the insn that sets "x = b;"
899 TEMP3 to the insn that sets "x = a;"
900 TEMP4 to the set of "x = a"; */
902 if (this_is_simplejump
903 && (temp2 = next_active_insn (insn)) != 0
904 && GET_CODE (temp2) == INSN
905 && (temp4 = single_set (temp2)) != 0
906 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
907 && (! SMALL_REGISTER_CLASSES
908 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
909 && (temp3 = prev_active_insn (insn)) != 0
910 && GET_CODE (temp3) == INSN
911 && (temp4 = single_set (temp3)) != 0
912 && rtx_equal_p (SET_DEST (temp4), temp1)
913 && (GET_CODE (SET_SRC (temp4)) == REG
914 || GET_CODE (SET_SRC (temp4)) == SUBREG
915 || (GET_CODE (SET_SRC (temp4)) == MEM
916 && RTX_UNCHANGING_P (SET_SRC (temp4)))
917 || CONSTANT_P (SET_SRC (temp4)))
918 && (REG_NOTES (temp3) == 0
919 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
920 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
921 && XEXP (REG_NOTES (temp3), 1) == 0
922 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
924 && (temp = prev_active_insn (temp3)) != 0
925 && condjump_p (temp) && ! simplejump_p (temp)
926 /* TEMP must skip over the "x = a;" insn */
927 && prev_real_insn (JUMP_LABEL (temp)) == insn
928 && no_labels_between_p (temp, insn))
930 rtx prev_label = JUMP_LABEL (temp);
931 rtx insert_after = prev_nonnote_insn (temp);
934 /* We cannot insert anything between a set of cc and its use. */
935 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
936 && sets_cc0_p (PATTERN (insert_after)))
937 insert_after = prev_nonnote_insn (insert_after);
939 ++LABEL_NUSES (prev_label);
942 && no_labels_between_p (insert_after, temp)
943 && ! reg_referenced_between_p (temp1, insert_after, temp3)
944 && ! reg_referenced_between_p (temp1, temp3,
946 && ! reg_set_between_p (temp1, insert_after, temp)
947 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
948 || ! reg_set_between_p (SET_SRC (temp4),
950 && invert_jump (temp, JUMP_LABEL (insn)))
952 emit_insn_after_with_line_notes (PATTERN (temp3),
953 insert_after, temp3);
956 /* Set NEXT to an insn that we know won't go away. */
960 if (prev_label && --LABEL_NUSES (prev_label) == 0)
961 delete_insn (prev_label);
967 /* If we have if (...) x = exp; and branches are expensive,
968 EXP is a single insn, does not have any side effects, cannot
969 trap, and is not too costly, convert this to
970 t = exp; if (...) x = t;
972 Don't do this when we have CC0 because it is unlikely to help
973 and we'd need to worry about where to place the new insn and
974 the potential for conflicts. We also can't do this when we have
975 notes on the insn for the same reason as above.
979 TEMP to the "x = exp;" insn.
980 TEMP1 to the single set in the "x = exp; insn.
983 if (! reload_completed
984 && this_is_condjump && ! this_is_simplejump
986 && (temp = next_nonnote_insn (insn)) != 0
987 && GET_CODE (temp) == INSN
988 && REG_NOTES (temp) == 0
989 && (reallabelprev == temp
990 || ((temp2 = next_active_insn (temp)) != 0
991 && simplejump_p (temp2)
992 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
993 && (temp1 = single_set (temp)) != 0
994 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
995 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
996 && (! SMALL_REGISTER_CLASSES
997 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
998 && GET_CODE (SET_SRC (temp1)) != REG
999 && GET_CODE (SET_SRC (temp1)) != SUBREG
1000 && GET_CODE (SET_SRC (temp1)) != CONST_INT
1001 && ! side_effects_p (SET_SRC (temp1))
1002 && ! may_trap_p (SET_SRC (temp1))
1003 && rtx_cost (SET_SRC (temp1), SET) < 10)
1005 rtx new = gen_reg_rtx (GET_MODE (temp2));
1007 if ((temp3 = find_insert_position (insn, temp))
1008 && validate_change (temp, &SET_DEST (temp1), new, 0))
1010 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1011 emit_insn_after_with_line_notes (PATTERN (temp),
1012 PREV_INSN (temp3), temp);
1014 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1018 /* Similarly, if it takes two insns to compute EXP but they
1019 have the same destination. Here TEMP3 will be the second
1020 insn and TEMP4 the SET from that insn. */
1022 if (! reload_completed
1023 && this_is_condjump && ! this_is_simplejump
1025 && (temp = next_nonnote_insn (insn)) != 0
1026 && GET_CODE (temp) == INSN
1027 && REG_NOTES (temp) == 0
1028 && (temp3 = next_nonnote_insn (temp)) != 0
1029 && GET_CODE (temp3) == INSN
1030 && REG_NOTES (temp3) == 0
1031 && (reallabelprev == temp3
1032 || ((temp2 = next_active_insn (temp3)) != 0
1033 && simplejump_p (temp2)
1034 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1035 && (temp1 = single_set (temp)) != 0
1036 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
1037 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1038 && (! SMALL_REGISTER_CLASSES
1039 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
1040 && ! side_effects_p (SET_SRC (temp1))
1041 && ! may_trap_p (SET_SRC (temp1))
1042 && rtx_cost (SET_SRC (temp1), SET) < 10
1043 && (temp4 = single_set (temp3)) != 0
1044 && rtx_equal_p (SET_DEST (temp4), temp2)
1045 && ! side_effects_p (SET_SRC (temp4))
1046 && ! may_trap_p (SET_SRC (temp4))
1047 && rtx_cost (SET_SRC (temp4), SET) < 10)
1049 rtx new = gen_reg_rtx (GET_MODE (temp2));
1051 if ((temp5 = find_insert_position (insn, temp))
1052 && (temp6 = find_insert_position (insn, temp3))
1053 && validate_change (temp, &SET_DEST (temp1), new, 0))
1055 /* Use the earliest of temp5 and temp6. */
1058 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1059 emit_insn_after_with_line_notes (PATTERN (temp),
1060 PREV_INSN (temp6), temp);
1061 emit_insn_after_with_line_notes
1062 (replace_rtx (PATTERN (temp3), temp2, new),
1063 PREV_INSN (temp6), temp3);
1065 delete_insn (temp3);
1066 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1070 /* Finally, handle the case where two insns are used to
1071 compute EXP but a temporary register is used. Here we must
1072 ensure that the temporary register is not used anywhere else. */
1074 if (! reload_completed
1076 && this_is_condjump && ! this_is_simplejump
1078 && (temp = next_nonnote_insn (insn)) != 0
1079 && GET_CODE (temp) == INSN
1080 && REG_NOTES (temp) == 0
1081 && (temp3 = next_nonnote_insn (temp)) != 0
1082 && GET_CODE (temp3) == INSN
1083 && REG_NOTES (temp3) == 0
1084 && (reallabelprev == temp3
1085 || ((temp2 = next_active_insn (temp3)) != 0
1086 && simplejump_p (temp2)
1087 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1088 && (temp1 = single_set (temp)) != 0
1089 && (temp5 = SET_DEST (temp1),
1090 (GET_CODE (temp5) == REG
1091 || (GET_CODE (temp5) == SUBREG
1092 && (temp5 = SUBREG_REG (temp5),
1093 GET_CODE (temp5) == REG))))
1094 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
1095 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
1096 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
1097 && ! side_effects_p (SET_SRC (temp1))
1098 && ! may_trap_p (SET_SRC (temp1))
1099 && rtx_cost (SET_SRC (temp1), SET) < 10
1100 && (temp4 = single_set (temp3)) != 0
1101 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
1102 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1103 && (! SMALL_REGISTER_CLASSES
1104 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
1105 && rtx_equal_p (SET_DEST (temp4), temp2)
1106 && ! side_effects_p (SET_SRC (temp4))
1107 && ! may_trap_p (SET_SRC (temp4))
1108 && rtx_cost (SET_SRC (temp4), SET) < 10)
1110 rtx new = gen_reg_rtx (GET_MODE (temp2));
1112 if ((temp5 = find_insert_position (insn, temp))
1113 && (temp6 = find_insert_position (insn, temp3))
1114 && validate_change (temp3, &SET_DEST (temp4), new, 0))
1116 /* Use the earliest of temp5 and temp6. */
1119 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1120 emit_insn_after_with_line_notes (PATTERN (temp),
1121 PREV_INSN (temp6), temp);
1122 emit_insn_after_with_line_notes (PATTERN (temp3),
1123 PREV_INSN (temp6), temp3);
1125 delete_insn (temp3);
1126 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1129 #endif /* HAVE_cc0 */
1131 /* Try to use a conditional move (if the target has them), or a
1132 store-flag insn. The general case is:
1134 1) x = a; if (...) x = b; and
1137 If the jump would be faster, the machine should not have defined
1138 the movcc or scc insns!. These cases are often made by the
1139 previous optimization.
1141 The second case is treated as x = x; if (...) x = b;.
1143 INSN here is the jump around the store. We set:
1145 TEMP to the "x = b;" insn.
1148 TEMP3 to A (X in the second case).
1149 TEMP4 to the condition being tested.
1150 TEMP5 to the earliest insn used to find the condition. */
1152 if (/* We can't do this after reload has completed. */
1154 && this_is_condjump && ! this_is_simplejump
1155 /* Set TEMP to the "x = b;" insn. */
1156 && (temp = next_nonnote_insn (insn)) != 0
1157 && GET_CODE (temp) == INSN
1158 && GET_CODE (PATTERN (temp)) == SET
1159 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1160 && (! SMALL_REGISTER_CLASSES
1161 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
1162 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1163 || (GET_CODE (temp2) == MEM && RTX_UNCHANGING_P (temp2))
1164 || GET_CODE (temp2) == SUBREG
1165 /* ??? How about floating point constants? */
1166 || CONSTANT_P (temp2))
1167 /* Allow either form, but prefer the former if both apply.
1168 There is no point in using the old value of TEMP1 if
1169 it is a register, since cse will alias them. It can
1170 lose if the old value were a hard register since CSE
1171 won't replace hard registers. Avoid using TEMP3 if
1172 small register classes and it is a hard register. */
1173 && (((temp3 = reg_set_last (temp1, insn)) != 0
1174 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
1175 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
1176 /* Make the latter case look like x = x; if (...) x = b; */
1177 || (temp3 = temp1, 1))
1178 /* INSN must either branch to the insn after TEMP or the insn
1179 after TEMP must branch to the same place as INSN. */
1180 && (reallabelprev == temp
1181 || ((temp4 = next_active_insn (temp)) != 0
1182 && simplejump_p (temp4)
1183 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1184 && (temp4 = get_condition (insn, &temp5)) != 0
1185 /* We must be comparing objects whose modes imply the size.
1186 We could handle BLKmode if (1) emit_store_flag could
1187 and (2) we could find the size reliably. */
1188 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1189 /* Even if branches are cheap, the store_flag optimization
1190 can win when the operation to be performed can be
1191 expressed directly. */
1193 /* If the previous insn sets CC0 and something else, we can't
1194 do this since we are going to delete that insn. */
1196 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1197 && GET_CODE (temp6) == INSN
1198 && (sets_cc0_p (PATTERN (temp6)) == -1
1199 || (sets_cc0_p (PATTERN (temp6)) == 1
1200 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1204 #ifdef HAVE_conditional_move
1205 /* First try a conditional move. */
1207 enum rtx_code code = GET_CODE (temp4);
1209 rtx cond0, cond1, aval, bval;
1212 /* Copy the compared variables into cond0 and cond1, so that
1213 any side effects performed in or after the old comparison,
1214 will not affect our compare which will come later. */
1215 /* ??? Is it possible to just use the comparison in the jump
1216 insn? After all, we're going to delete it. We'd have
1217 to modify emit_conditional_move to take a comparison rtx
1218 instead or write a new function. */
1219 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1220 /* We want the target to be able to simplify comparisons with
1221 zero (and maybe other constants as well), so don't create
1222 pseudos for them. There's no need to either. */
1223 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1224 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1225 cond1 = XEXP (temp4, 1);
1227 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1233 target = emit_conditional_move (var, code,
1234 cond0, cond1, VOIDmode,
1235 aval, bval, GET_MODE (var),
1236 (code == LTU || code == GEU
1237 || code == LEU || code == GTU));
1243 /* Save the conditional move sequence but don't emit it
1244 yet. On some machines, like the alpha, it is possible
1245 that temp5 == insn, so next generate the sequence that
1246 saves the compared values and then emit both
1247 sequences ensuring seq1 occurs before seq2. */
1248 seq2 = get_insns ();
1251 /* Now that we can't fail, generate the copy insns that
1252 preserve the compared values. */
1254 emit_move_insn (cond0, XEXP (temp4, 0));
1255 if (cond1 != XEXP (temp4, 1))
1256 emit_move_insn (cond1, XEXP (temp4, 1));
1257 seq1 = get_insns ();
1260 emit_insns_before (seq1, temp5);
1261 /* Insert conditional move after insn, to be sure that
1262 the jump and a possible compare won't be separated */
1263 emit_insns_after (seq2, insn);
1265 /* ??? We can also delete the insn that sets X to A.
1266 Flow will do it too though. */
1268 next = NEXT_INSN (insn);
1278 /* That didn't work, try a store-flag insn.
1280 We further divide the cases into:
1282 1) x = a; if (...) x = b; and either A or B is zero,
1283 2) if (...) x = 0; and jumps are expensive,
1284 3) x = a; if (...) x = b; and A and B are constants where all
1285 the set bits in A are also set in B and jumps are expensive,
1286 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1288 5) if (...) x = b; if jumps are even more expensive. */
1290 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1291 && ((GET_CODE (temp3) == CONST_INT)
1292 /* Make the latter case look like
1293 x = x; if (...) x = 0; */
1296 && temp2 == const0_rtx)
1297 || BRANCH_COST >= 3)))
1298 /* If B is zero, OK; if A is zero, can only do (1) if we
1299 can reverse the condition. See if (3) applies possibly
1300 by reversing the condition. Prefer reversing to (4) when
1301 branches are very expensive. */
1302 && (((BRANCH_COST >= 2
1303 || STORE_FLAG_VALUE == -1
1304 || (STORE_FLAG_VALUE == 1
1305 /* Check that the mask is a power of two,
1306 so that it can probably be generated
1308 && exact_log2 (INTVAL (temp3)) >= 0))
1309 && (reversep = 0, temp2 == const0_rtx))
1310 || ((BRANCH_COST >= 2
1311 || STORE_FLAG_VALUE == -1
1312 || (STORE_FLAG_VALUE == 1
1313 && exact_log2 (INTVAL (temp2)) >= 0))
1314 && temp3 == const0_rtx
1315 && (reversep = can_reverse_comparison_p (temp4, insn)))
1316 || (BRANCH_COST >= 2
1317 && GET_CODE (temp2) == CONST_INT
1318 && GET_CODE (temp3) == CONST_INT
1319 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1320 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1321 && (reversep = can_reverse_comparison_p (temp4,
1323 || BRANCH_COST >= 3)
1326 enum rtx_code code = GET_CODE (temp4);
1327 rtx uval, cval, var = temp1;
1331 /* If necessary, reverse the condition. */
1333 code = reverse_condition (code), uval = temp2, cval = temp3;
1335 uval = temp3, cval = temp2;
1337 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1338 is the constant 1, it is best to just compute the result
1339 directly. If UVAL is constant and STORE_FLAG_VALUE
1340 includes all of its bits, it is best to compute the flag
1341 value unnormalized and `and' it with UVAL. Otherwise,
1342 normalize to -1 and `and' with UVAL. */
1343 normalizep = (cval != const0_rtx ? -1
1344 : (uval == const1_rtx ? 1
1345 : (GET_CODE (uval) == CONST_INT
1346 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1349 /* We will be putting the store-flag insn immediately in
1350 front of the comparison that was originally being done,
1351 so we know all the variables in TEMP4 will be valid.
1352 However, this might be in front of the assignment of
1353 A to VAR. If it is, it would clobber the store-flag
1354 we will be emitting.
1356 Therefore, emit into a temporary which will be copied to
1357 VAR immediately after TEMP. */
1360 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1361 XEXP (temp4, 0), XEXP (temp4, 1),
1363 (code == LTU || code == LEU
1364 || code == GEU || code == GTU),
1374 /* Put the store-flag insns in front of the first insn
1375 used to compute the condition to ensure that we
1376 use the same values of them as the current
1377 comparison. However, the remainder of the insns we
1378 generate will be placed directly in front of the
1379 jump insn, in case any of the pseudos we use
1380 are modified earlier. */
1382 emit_insns_before (seq, temp5);
1386 /* Both CVAL and UVAL are non-zero. */
1387 if (cval != const0_rtx && uval != const0_rtx)
1391 tem1 = expand_and (uval, target, NULL_RTX);
1392 if (GET_CODE (cval) == CONST_INT
1393 && GET_CODE (uval) == CONST_INT
1394 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1398 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1399 target, NULL_RTX, 0);
1400 tem2 = expand_and (cval, tem2,
1401 (GET_CODE (tem2) == REG
1405 /* If we usually make new pseudos, do so here. This
1406 turns out to help machines that have conditional
1408 /* ??? Conditional moves have already been handled.
1409 This may be obsolete. */
1411 if (flag_expensive_optimizations)
1414 target = expand_binop (GET_MODE (var), ior_optab,
1418 else if (normalizep != 1)
1420 /* We know that either CVAL or UVAL is zero. If
1421 UVAL is zero, negate TARGET and `and' with CVAL.
1422 Otherwise, `and' with UVAL. */
1423 if (uval == const0_rtx)
1425 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1426 target, NULL_RTX, 0);
1430 target = expand_and (uval, target,
1431 (GET_CODE (target) == REG
1432 && ! preserve_subexpressions_p ()
1433 ? target : NULL_RTX));
1436 emit_move_insn (var, target);
1440 /* If INSN uses CC0, we must not separate it from the
1441 insn that sets cc0. */
1442 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1443 before = prev_nonnote_insn (before);
1445 emit_insns_before (seq, before);
1448 next = NEXT_INSN (insn);
1458 /* If branches are expensive, convert
1459 if (foo) bar++; to bar += (foo != 0);
1460 and similarly for "bar--;"
1462 INSN is the conditional branch around the arithmetic. We set:
1464 TEMP is the arithmetic insn.
1465 TEMP1 is the SET doing the arithmetic.
1466 TEMP2 is the operand being incremented or decremented.
1467 TEMP3 to the condition being tested.
1468 TEMP4 to the earliest insn used to find the condition. */
1470 if ((BRANCH_COST >= 2
1478 && ! reload_completed
1479 && this_is_condjump && ! this_is_simplejump
1480 && (temp = next_nonnote_insn (insn)) != 0
1481 && (temp1 = single_set (temp)) != 0
1482 && (temp2 = SET_DEST (temp1),
1483 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1484 && GET_CODE (SET_SRC (temp1)) == PLUS
1485 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1486 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1487 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1488 && ! side_effects_p (temp2)
1489 && ! may_trap_p (temp2)
1490 /* INSN must either branch to the insn after TEMP or the insn
1491 after TEMP must branch to the same place as INSN. */
1492 && (reallabelprev == temp
1493 || ((temp3 = next_active_insn (temp)) != 0
1494 && simplejump_p (temp3)
1495 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1496 && (temp3 = get_condition (insn, &temp4)) != 0
1497 /* We must be comparing objects whose modes imply the size.
1498 We could handle BLKmode if (1) emit_store_flag could
1499 and (2) we could find the size reliably. */
1500 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1501 && can_reverse_comparison_p (temp3, insn))
1503 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1504 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1508 /* It must be the case that TEMP2 is not modified in the range
1509 [TEMP4, INSN). The one exception we make is if the insn
1510 before INSN sets TEMP2 to something which is also unchanged
1511 in that range. In that case, we can move the initialization
1512 into our sequence. */
1514 if ((temp5 = prev_active_insn (insn)) != 0
1515 && no_labels_between_p (temp5, insn)
1516 && GET_CODE (temp5) == INSN
1517 && (temp6 = single_set (temp5)) != 0
1518 && rtx_equal_p (temp2, SET_DEST (temp6))
1519 && (CONSTANT_P (SET_SRC (temp6))
1520 || GET_CODE (SET_SRC (temp6)) == REG
1521 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1523 emit_insn (PATTERN (temp5));
1525 init = SET_SRC (temp6);
1528 if (CONSTANT_P (init)
1529 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1530 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1531 XEXP (temp3, 0), XEXP (temp3, 1),
1533 (code == LTU || code == LEU
1534 || code == GTU || code == GEU), 1);
1536 /* If we can do the store-flag, do the addition or
1540 target = expand_binop (GET_MODE (temp2),
1541 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1542 ? add_optab : sub_optab),
1543 temp2, target, temp2, 0, OPTAB_WIDEN);
1547 /* Put the result back in temp2 in case it isn't already.
1548 Then replace the jump, possible a CC0-setting insn in
1549 front of the jump, and TEMP, with the sequence we have
1552 if (target != temp2)
1553 emit_move_insn (temp2, target);
1558 emit_insns_before (seq, temp4);
1562 delete_insn (init_insn);
1564 next = NEXT_INSN (insn);
1566 delete_insn (prev_nonnote_insn (insn));
1576 /* Simplify if (...) x = 1; else {...} if (x) ...
1577 We recognize this case scanning backwards as well.
1579 TEMP is the assignment to x;
1580 TEMP1 is the label at the head of the second if. */
1581 /* ?? This should call get_condition to find the values being
1582 compared, instead of looking for a COMPARE insn when HAVE_cc0
1583 is not defined. This would allow it to work on the m88k. */
1584 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1585 is not defined and the condition is tested by a separate compare
1586 insn. This is because the code below assumes that the result
1587 of the compare dies in the following branch.
1589 Not only that, but there might be other insns between the
1590 compare and branch whose results are live. Those insns need
1593 A way to fix this is to move the insns at JUMP_LABEL (insn)
1594 to before INSN. If we are running before flow, they will
1595 be deleted if they aren't needed. But this doesn't work
1598 This is really a special-case of jump threading, anyway. The
1599 right thing to do is to replace this and jump threading with
1600 much simpler code in cse.
1602 This code has been turned off in the non-cc0 case in the
1606 else if (this_is_simplejump
1607 /* Safe to skip USE and CLOBBER insns here
1608 since they will not be deleted. */
1609 && (temp = prev_active_insn (insn))
1610 && no_labels_between_p (temp, insn)
1611 && GET_CODE (temp) == INSN
1612 && GET_CODE (PATTERN (temp)) == SET
1613 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1614 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1615 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1616 /* If we find that the next value tested is `x'
1617 (TEMP1 is the insn where this happens), win. */
1618 && GET_CODE (temp1) == INSN
1619 && GET_CODE (PATTERN (temp1)) == SET
1621 /* Does temp1 `tst' the value of x? */
1622 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1623 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1624 && (temp1 = next_nonnote_insn (temp1))
1626 /* Does temp1 compare the value of x against zero? */
1627 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1628 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1629 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1630 == SET_DEST (PATTERN (temp)))
1631 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1632 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1634 && condjump_p (temp1))
1636 /* Get the if_then_else from the condjump. */
1637 rtx choice = SET_SRC (PATTERN (temp1));
1638 if (GET_CODE (choice) == IF_THEN_ELSE)
1640 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1641 rtx val = SET_SRC (PATTERN (temp));
1643 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1647 if (cond == const_true_rtx)
1648 ultimate = XEXP (choice, 1);
1649 else if (cond == const0_rtx)
1650 ultimate = XEXP (choice, 2);
1654 if (ultimate == pc_rtx)
1655 ultimate = get_label_after (temp1);
1656 else if (ultimate && GET_CODE (ultimate) != RETURN)
1657 ultimate = XEXP (ultimate, 0);
1659 if (ultimate && JUMP_LABEL(insn) != ultimate)
1660 changed |= redirect_jump (insn, ultimate);
1666 /* @@ This needs a bit of work before it will be right.
1668 Any type of comparison can be accepted for the first and
1669 second compare. When rewriting the first jump, we must
1670 compute the what conditions can reach label3, and use the
1671 appropriate code. We can not simply reverse/swap the code
1672 of the first jump. In some cases, the second jump must be
1676 < == converts to > ==
1677 < != converts to == >
1680 If the code is written to only accept an '==' test for the second
1681 compare, then all that needs to be done is to swap the condition
1682 of the first branch.
1684 It is questionable whether we want this optimization anyways,
1685 since if the user wrote code like this because he/she knew that
1686 the jump to label1 is taken most of the time, then rewriting
1687 this gives slower code. */
1688 /* @@ This should call get_condition to find the values being
1689 compared, instead of looking for a COMPARE insn when HAVE_cc0
1690 is not defined. This would allow it to work on the m88k. */
1691 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1692 is not defined and the condition is tested by a separate compare
1693 insn. This is because the code below assumes that the result
1694 of the compare dies in the following branch. */
1696 /* Simplify test a ~= b
1710 where ~= is an inequality, e.g. >, and ~~= is the swapped
1713 We recognize this case scanning backwards.
1715 TEMP is the conditional jump to `label2';
1716 TEMP1 is the test for `a == b';
1717 TEMP2 is the conditional jump to `label1';
1718 TEMP3 is the test for `a ~= b'. */
1719 else if (this_is_simplejump
1720 && (temp = prev_active_insn (insn))
1721 && no_labels_between_p (temp, insn)
1722 && condjump_p (temp)
1723 && (temp1 = prev_active_insn (temp))
1724 && no_labels_between_p (temp1, temp)
1725 && GET_CODE (temp1) == INSN
1726 && GET_CODE (PATTERN (temp1)) == SET
1728 && sets_cc0_p (PATTERN (temp1)) == 1
1730 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1731 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1732 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1734 && (temp2 = prev_active_insn (temp1))
1735 && no_labels_between_p (temp2, temp1)
1736 && condjump_p (temp2)
1737 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1738 && (temp3 = prev_active_insn (temp2))
1739 && no_labels_between_p (temp3, temp2)
1740 && GET_CODE (PATTERN (temp3)) == SET
1741 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1742 SET_DEST (PATTERN (temp1)))
1743 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1744 SET_SRC (PATTERN (temp3)))
1745 && ! inequality_comparisons_p (PATTERN (temp))
1746 && inequality_comparisons_p (PATTERN (temp2)))
1748 rtx fallthrough_label = JUMP_LABEL (temp2);
1750 ++LABEL_NUSES (fallthrough_label);
1751 if (swap_jump (temp2, JUMP_LABEL (insn)))
1757 if (--LABEL_NUSES (fallthrough_label) == 0)
1758 delete_insn (fallthrough_label);
1761 /* Simplify if (...) {... x = 1;} if (x) ...
1763 We recognize this case backwards.
1765 TEMP is the test of `x';
1766 TEMP1 is the assignment to `x' at the end of the
1767 previous statement. */
1768 /* @@ This should call get_condition to find the values being
1769 compared, instead of looking for a COMPARE insn when HAVE_cc0
1770 is not defined. This would allow it to work on the m88k. */
1771 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1772 is not defined and the condition is tested by a separate compare
1773 insn. This is because the code below assumes that the result
1774 of the compare dies in the following branch. */
1776 /* ??? This has to be turned off. The problem is that the
1777 unconditional jump might indirectly end up branching to the
1778 label between TEMP1 and TEMP. We can't detect this, in general,
1779 since it may become a jump to there after further optimizations.
1780 If that jump is done, it will be deleted, so we will retry
1781 this optimization in the next pass, thus an infinite loop.
1783 The present code prevents this by putting the jump after the
1784 label, but this is not logically correct. */
1786 else if (this_is_condjump
1787 /* Safe to skip USE and CLOBBER insns here
1788 since they will not be deleted. */
1789 && (temp = prev_active_insn (insn))
1790 && no_labels_between_p (temp, insn)
1791 && GET_CODE (temp) == INSN
1792 && GET_CODE (PATTERN (temp)) == SET
1794 && sets_cc0_p (PATTERN (temp)) == 1
1795 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1797 /* Temp must be a compare insn, we can not accept a register
1798 to register move here, since it may not be simply a
1800 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1801 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1802 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1803 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1804 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1806 /* May skip USE or CLOBBER insns here
1807 for checking for opportunity, since we
1808 take care of them later. */
1809 && (temp1 = prev_active_insn (temp))
1810 && GET_CODE (temp1) == INSN
1811 && GET_CODE (PATTERN (temp1)) == SET
1813 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1815 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1816 == SET_DEST (PATTERN (temp1)))
1818 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1819 /* If this isn't true, cse will do the job. */
1820 && ! no_labels_between_p (temp1, temp))
1822 /* Get the if_then_else from the condjump. */
1823 rtx choice = SET_SRC (PATTERN (insn));
1824 if (GET_CODE (choice) == IF_THEN_ELSE
1825 && (GET_CODE (XEXP (choice, 0)) == EQ
1826 || GET_CODE (XEXP (choice, 0)) == NE))
1828 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1833 /* Get the place that condjump will jump to
1834 if it is reached from here. */
1835 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1837 ultimate = XEXP (choice, 1);
1839 ultimate = XEXP (choice, 2);
1840 /* Get it as a CODE_LABEL. */
1841 if (ultimate == pc_rtx)
1842 ultimate = get_label_after (insn);
1844 /* Get the label out of the LABEL_REF. */
1845 ultimate = XEXP (ultimate, 0);
1847 /* Insert the jump immediately before TEMP, specifically
1848 after the label that is between TEMP1 and TEMP. */
1849 last_insn = PREV_INSN (temp);
1851 /* If we would be branching to the next insn, the jump
1852 would immediately be deleted and the re-inserted in
1853 a subsequent pass over the code. So don't do anything
1855 if (next_active_insn (last_insn)
1856 != next_active_insn (ultimate))
1858 emit_barrier_after (last_insn);
1859 p = emit_jump_insn_after (gen_jump (ultimate),
1861 JUMP_LABEL (p) = ultimate;
1862 ++LABEL_NUSES (ultimate);
1863 if (INSN_UID (ultimate) < max_jump_chain
1864 && INSN_CODE (p) < max_jump_chain)
1866 jump_chain[INSN_UID (p)]
1867 = jump_chain[INSN_UID (ultimate)];
1868 jump_chain[INSN_UID (ultimate)] = p;
1876 /* Detect a conditional jump going to the same place
1877 as an immediately following unconditional jump. */
1878 else if (this_is_condjump
1879 && (temp = next_active_insn (insn)) != 0
1880 && simplejump_p (temp)
1881 && (next_active_insn (JUMP_LABEL (insn))
1882 == next_active_insn (JUMP_LABEL (temp))))
1886 /* ??? Optional. Disables some optimizations, but makes
1887 gcov output more accurate with -O. */
1888 if (flag_test_coverage && !reload_completed)
1889 for (tem = insn; tem != temp; tem = NEXT_INSN (tem))
1890 if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0)
1900 /* Detect a conditional jump jumping over an unconditional jump. */
1902 else if ((this_is_condjump || this_is_condjump_in_parallel)
1903 && ! this_is_simplejump
1904 && reallabelprev != 0
1905 && GET_CODE (reallabelprev) == JUMP_INSN
1906 && prev_active_insn (reallabelprev) == insn
1907 && no_labels_between_p (insn, reallabelprev)
1908 && simplejump_p (reallabelprev))
1910 /* When we invert the unconditional jump, we will be
1911 decrementing the usage count of its old label.
1912 Make sure that we don't delete it now because that
1913 might cause the following code to be deleted. */
1914 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1915 rtx prev_label = JUMP_LABEL (insn);
1918 ++LABEL_NUSES (prev_label);
1920 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1922 /* It is very likely that if there are USE insns before
1923 this jump, they hold REG_DEAD notes. These REG_DEAD
1924 notes are no longer valid due to this optimization,
1925 and will cause the life-analysis that following passes
1926 (notably delayed-branch scheduling) to think that
1927 these registers are dead when they are not.
1929 To prevent this trouble, we just remove the USE insns
1930 from the insn chain. */
1932 while (prev_uses && GET_CODE (prev_uses) == INSN
1933 && GET_CODE (PATTERN (prev_uses)) == USE)
1935 rtx useless = prev_uses;
1936 prev_uses = prev_nonnote_insn (prev_uses);
1937 delete_insn (useless);
1940 delete_insn (reallabelprev);
1945 /* We can now safely delete the label if it is unreferenced
1946 since the delete_insn above has deleted the BARRIER. */
1947 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1948 delete_insn (prev_label);
1953 /* Detect a jump to a jump. */
1955 nlabel = follow_jumps (JUMP_LABEL (insn));
1956 if (nlabel != JUMP_LABEL (insn)
1957 && redirect_jump (insn, nlabel))
1963 /* Look for if (foo) bar; else break; */
1964 /* The insns look like this:
1965 insn = condjump label1;
1966 ...range1 (some insns)...
1969 ...range2 (some insns)...
1970 jump somewhere unconditionally
1973 rtx label1 = next_label (insn);
1974 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1975 /* Don't do this optimization on the first round, so that
1976 jump-around-a-jump gets simplified before we ask here
1977 whether a jump is unconditional.
1979 Also don't do it when we are called after reload since
1980 it will confuse reorg. */
1982 && (reload_completed ? ! flag_delayed_branch : 1)
1983 /* Make sure INSN is something we can invert. */
1984 && condjump_p (insn)
1986 && JUMP_LABEL (insn) == label1
1987 && LABEL_NUSES (label1) == 1
1988 && GET_CODE (range1end) == JUMP_INSN
1989 && simplejump_p (range1end))
1991 rtx label2 = next_label (label1);
1992 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1993 if (range1end != range2end
1994 && JUMP_LABEL (range1end) == label2
1995 && GET_CODE (range2end) == JUMP_INSN
1996 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1997 /* Invert the jump condition, so we
1998 still execute the same insns in each case. */
1999 && invert_jump (insn, label1))
2001 rtx range1beg = next_active_insn (insn);
2002 rtx range2beg = next_active_insn (label1);
2003 rtx range1after, range2after;
2004 rtx range1before, range2before;
2007 /* Include in each range any notes before it, to be
2008 sure that we get the line number note if any, even
2009 if there are other notes here. */
2010 while (PREV_INSN (range1beg)
2011 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
2012 range1beg = PREV_INSN (range1beg);
2014 while (PREV_INSN (range2beg)
2015 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
2016 range2beg = PREV_INSN (range2beg);
2018 /* Don't move NOTEs for blocks or loops; shift them
2019 outside the ranges, where they'll stay put. */
2020 range1beg = squeeze_notes (range1beg, range1end);
2021 range2beg = squeeze_notes (range2beg, range2end);
2023 /* Get current surrounds of the 2 ranges. */
2024 range1before = PREV_INSN (range1beg);
2025 range2before = PREV_INSN (range2beg);
2026 range1after = NEXT_INSN (range1end);
2027 range2after = NEXT_INSN (range2end);
2029 /* Splice range2 where range1 was. */
2030 NEXT_INSN (range1before) = range2beg;
2031 PREV_INSN (range2beg) = range1before;
2032 NEXT_INSN (range2end) = range1after;
2033 PREV_INSN (range1after) = range2end;
2034 /* Splice range1 where range2 was. */
2035 NEXT_INSN (range2before) = range1beg;
2036 PREV_INSN (range1beg) = range2before;
2037 NEXT_INSN (range1end) = range2after;
2038 PREV_INSN (range2after) = range1end;
2040 /* Check for a loop end note between the end of
2041 range2, and the next code label. If there is one,
2042 then what we have really seen is
2043 if (foo) break; end_of_loop;
2044 and moved the break sequence outside the loop.
2045 We must move the LOOP_END note to where the
2046 loop really ends now, or we will confuse loop
2047 optimization. Stop if we find a LOOP_BEG note
2048 first, since we don't want to move the LOOP_END
2049 note in that case. */
2050 for (;range2after != label2; range2after = rangenext)
2052 rangenext = NEXT_INSN (range2after);
2053 if (GET_CODE (range2after) == NOTE)
2055 if (NOTE_LINE_NUMBER (range2after)
2056 == NOTE_INSN_LOOP_END)
2058 NEXT_INSN (PREV_INSN (range2after))
2060 PREV_INSN (rangenext)
2061 = PREV_INSN (range2after);
2062 PREV_INSN (range2after)
2063 = PREV_INSN (range1beg);
2064 NEXT_INSN (range2after) = range1beg;
2065 NEXT_INSN (PREV_INSN (range1beg))
2067 PREV_INSN (range1beg) = range2after;
2069 else if (NOTE_LINE_NUMBER (range2after)
2070 == NOTE_INSN_LOOP_BEG)
2080 /* Now that the jump has been tensioned,
2081 try cross jumping: check for identical code
2082 before the jump and before its target label. */
2084 /* First, cross jumping of conditional jumps: */
2086 if (cross_jump && condjump_p (insn))
2088 rtx newjpos, newlpos;
2089 rtx x = prev_real_insn (JUMP_LABEL (insn));
2091 /* A conditional jump may be crossjumped
2092 only if the place it jumps to follows
2093 an opposing jump that comes back here. */
2095 if (x != 0 && ! jump_back_p (x, insn))
2096 /* We have no opposing jump;
2097 cannot cross jump this insn. */
2101 /* TARGET is nonzero if it is ok to cross jump
2102 to code before TARGET. If so, see if matches. */
2104 find_cross_jump (insn, x, 2,
2105 &newjpos, &newlpos);
2109 do_cross_jump (insn, newjpos, newlpos);
2110 /* Make the old conditional jump
2111 into an unconditional one. */
2112 SET_SRC (PATTERN (insn))
2113 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
2114 INSN_CODE (insn) = -1;
2115 emit_barrier_after (insn);
2116 /* Add to jump_chain unless this is a new label
2117 whose UID is too large. */
2118 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
2120 jump_chain[INSN_UID (insn)]
2121 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2122 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2129 /* Cross jumping of unconditional jumps:
2130 a few differences. */
2132 if (cross_jump && simplejump_p (insn))
2134 rtx newjpos, newlpos;
2139 /* TARGET is nonzero if it is ok to cross jump
2140 to code before TARGET. If so, see if matches. */
2141 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2142 &newjpos, &newlpos);
2144 /* If cannot cross jump to code before the label,
2145 see if we can cross jump to another jump to
2147 /* Try each other jump to this label. */
2148 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2149 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2150 target != 0 && newjpos == 0;
2151 target = jump_chain[INSN_UID (target)])
2153 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2154 /* Ignore TARGET if it's deleted. */
2155 && ! INSN_DELETED_P (target))
2156 find_cross_jump (insn, target, 2,
2157 &newjpos, &newlpos);
2161 do_cross_jump (insn, newjpos, newlpos);
2167 /* This code was dead in the previous jump.c! */
2168 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2170 /* Return insns all "jump to the same place"
2171 so we can cross-jump between any two of them. */
2173 rtx newjpos, newlpos, target;
2177 /* If cannot cross jump to code before the label,
2178 see if we can cross jump to another jump to
2180 /* Try each other jump to this label. */
2181 for (target = jump_chain[0];
2182 target != 0 && newjpos == 0;
2183 target = jump_chain[INSN_UID (target)])
2185 && ! INSN_DELETED_P (target)
2186 && GET_CODE (PATTERN (target)) == RETURN)
2187 find_cross_jump (insn, target, 2,
2188 &newjpos, &newlpos);
2192 do_cross_jump (insn, newjpos, newlpos);
2203 /* Delete extraneous line number notes.
2204 Note that two consecutive notes for different lines are not really
2205 extraneous. There should be some indication where that line belonged,
2206 even if it became empty. */
2211 for (insn = f; insn; insn = NEXT_INSN (insn))
2212 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2214 /* Delete this note if it is identical to previous note. */
2216 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2217 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2230 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2231 in front of it. If the machine allows it at this point (we might be
2232 after reload for a leaf routine), it will improve optimization for it
2233 to be there. We do this both here and at the start of this pass since
2234 the RETURN might have been deleted by some of our optimizations. */
2235 insn = get_last_insn ();
2236 while (insn && GET_CODE (insn) == NOTE)
2237 insn = PREV_INSN (insn);
2239 if (insn && GET_CODE (insn) != BARRIER)
2241 emit_jump_insn (gen_return ());
2247 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2248 If so, delete it, and record that this function can drop off the end. */
2254 /* One label can follow the end-note: the return label. */
2255 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2256 /* Ordinary insns can follow it if returning a structure. */
2257 || GET_CODE (insn) == INSN
2258 /* If machine uses explicit RETURN insns, no epilogue,
2259 then one of them follows the note. */
2260 || (GET_CODE (insn) == JUMP_INSN
2261 && GET_CODE (PATTERN (insn)) == RETURN)
2262 /* A barrier can follow the return insn. */
2263 || GET_CODE (insn) == BARRIER
2264 /* Other kinds of notes can follow also. */
2265 || (GET_CODE (insn) == NOTE
2266 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2267 insn = PREV_INSN (insn);
2270 /* Report if control can fall through at the end of the function. */
2271 if (insn && GET_CODE (insn) == NOTE
2272 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2278 /* Show JUMP_CHAIN no longer valid. */
2282 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2283 jump. Assume that this unconditional jump is to the exit test code. If
2284 the code is sufficiently simple, make a copy of it before INSN,
2285 followed by a jump to the exit of the loop. Then delete the unconditional
2288 Return 1 if we made the change, else 0.
2290 This is only safe immediately after a regscan pass because it uses the
2291 values of regno_first_uid and regno_last_uid. */
2294 duplicate_loop_exit_test (loop_start)
2297 rtx insn, set, reg, p, link;
2300 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2302 int max_reg = max_reg_num ();
2305 /* Scan the exit code. We do not perform this optimization if any insn:
2309 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2310 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2311 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2314 Also, don't do this if the exit code is more than 20 insns. */
2316 for (insn = exitcode;
2318 && ! (GET_CODE (insn) == NOTE
2319 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2320 insn = NEXT_INSN (insn))
2322 switch (GET_CODE (insn))
2328 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2329 a jump immediately after the loop start that branches outside
2330 the loop but within an outer loop, near the exit test.
2331 If we copied this exit test and created a phony
2332 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2333 before the exit test look like these could be safely moved
2334 out of the loop even if they actually may be never executed.
2335 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2337 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2338 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2339 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2340 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2345 if (++num_insns > 20
2346 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2347 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2355 /* Unless INSN is zero, we can do the optimization. */
2361 /* See if any insn sets a register only used in the loop exit code and
2362 not a user variable. If so, replace it with a new register. */
2363 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2364 if (GET_CODE (insn) == INSN
2365 && (set = single_set (insn)) != 0
2366 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2367 || (GET_CODE (reg) == SUBREG
2368 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2369 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2370 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2372 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2373 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2378 /* We can do the replacement. Allocate reg_map if this is the
2379 first replacement we found. */
2382 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2383 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2386 REG_LOOP_TEST_P (reg) = 1;
2388 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2392 /* Now copy each insn. */
2393 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2394 switch (GET_CODE (insn))
2397 copy = emit_barrier_before (loop_start);
2400 /* Only copy line-number notes. */
2401 if (NOTE_LINE_NUMBER (insn) >= 0)
2403 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2404 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2409 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2411 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2413 mark_jump_label (PATTERN (copy), copy, 0);
2415 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2417 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2418 if (REG_NOTE_KIND (link) != REG_LABEL)
2420 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2423 if (reg_map && REG_NOTES (copy))
2424 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2428 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2430 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2431 mark_jump_label (PATTERN (copy), copy, 0);
2432 if (REG_NOTES (insn))
2434 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2436 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2439 /* If this is a simple jump, add it to the jump chain. */
2441 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2442 && simplejump_p (copy))
2444 jump_chain[INSN_UID (copy)]
2445 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2446 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2454 /* Now clean up by emitting a jump to the end label and deleting the jump
2455 at the start of the loop. */
2456 if (! copy || GET_CODE (copy) != BARRIER)
2458 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2460 mark_jump_label (PATTERN (copy), copy, 0);
2461 if (INSN_UID (copy) < max_jump_chain
2462 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2464 jump_chain[INSN_UID (copy)]
2465 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2466 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2468 emit_barrier_before (loop_start);
2471 /* Mark the exit code as the virtual top of the converted loop. */
2472 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2474 delete_insn (next_nonnote_insn (loop_start));
2479 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2480 loop-end notes between START and END out before START. Assume that
2481 END is not such a note. START may be such a note. Returns the value
2482 of the new starting insn, which may be different if the original start
2486 squeeze_notes (start, end)
2492 for (insn = start; insn != end; insn = next)
2494 next = NEXT_INSN (insn);
2495 if (GET_CODE (insn) == NOTE
2496 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2497 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2498 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2499 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2500 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2501 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2507 rtx prev = PREV_INSN (insn);
2508 PREV_INSN (insn) = PREV_INSN (start);
2509 NEXT_INSN (insn) = start;
2510 NEXT_INSN (PREV_INSN (insn)) = insn;
2511 PREV_INSN (NEXT_INSN (insn)) = insn;
2512 NEXT_INSN (prev) = next;
2513 PREV_INSN (next) = prev;
2521 /* Compare the instructions before insn E1 with those before E2
2522 to find an opportunity for cross jumping.
2523 (This means detecting identical sequences of insns followed by
2524 jumps to the same place, or followed by a label and a jump
2525 to that label, and replacing one with a jump to the other.)
2527 Assume E1 is a jump that jumps to label E2
2528 (that is not always true but it might as well be).
2529 Find the longest possible equivalent sequences
2530 and store the first insns of those sequences into *F1 and *F2.
2531 Store zero there if no equivalent preceding instructions are found.
2533 We give up if we find a label in stream 1.
2534 Actually we could transfer that label into stream 2. */
2537 find_cross_jump (e1, e2, minimum, f1, f2)
2542 register rtx i1 = e1, i2 = e2;
2543 register rtx p1, p2;
2546 rtx last1 = 0, last2 = 0;
2547 rtx afterlast1 = 0, afterlast2 = 0;
2554 i1 = prev_nonnote_insn (i1);
2556 i2 = PREV_INSN (i2);
2557 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2558 i2 = PREV_INSN (i2);
2563 /* Don't allow the range of insns preceding E1 or E2
2564 to include the other (E2 or E1). */
2565 if (i2 == e1 || i1 == e2)
2568 /* If we will get to this code by jumping, those jumps will be
2569 tensioned to go directly to the new label (before I2),
2570 so this cross-jumping won't cost extra. So reduce the minimum. */
2571 if (GET_CODE (i1) == CODE_LABEL)
2577 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2583 /* If this is a CALL_INSN, compare register usage information.
2584 If we don't check this on stack register machines, the two
2585 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2586 numbers of stack registers in the same basic block.
2587 If we don't check this on machines with delay slots, a delay slot may
2588 be filled that clobbers a parameter expected by the subroutine.
2590 ??? We take the simple route for now and assume that if they're
2591 equal, they were constructed identically. */
2593 if (GET_CODE (i1) == CALL_INSN
2594 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2595 CALL_INSN_FUNCTION_USAGE (i2)))
2599 /* If cross_jump_death_matters is not 0, the insn's mode
2600 indicates whether or not the insn contains any stack-like
2603 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2605 /* If register stack conversion has already been done, then
2606 death notes must also be compared before it is certain that
2607 the two instruction streams match. */
2610 HARD_REG_SET i1_regset, i2_regset;
2612 CLEAR_HARD_REG_SET (i1_regset);
2613 CLEAR_HARD_REG_SET (i2_regset);
2615 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2616 if (REG_NOTE_KIND (note) == REG_DEAD
2617 && STACK_REG_P (XEXP (note, 0)))
2618 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2620 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2621 if (REG_NOTE_KIND (note) == REG_DEAD
2622 && STACK_REG_P (XEXP (note, 0)))
2623 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2625 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2634 /* Don't allow old-style asm or volatile extended asms to be accepted
2635 for cross jumping purposes. It is conceptually correct to allow
2636 them, since cross-jumping preserves the dynamic instruction order
2637 even though it is changing the static instruction order. However,
2638 if an asm is being used to emit an assembler pseudo-op, such as
2639 the MIPS `.set reorder' pseudo-op, then the static instruction order
2640 matters and it must be preserved. */
2641 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
2642 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
2643 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
2646 if (lose || GET_CODE (p1) != GET_CODE (p2)
2647 || ! rtx_renumbered_equal_p (p1, p2))
2649 /* The following code helps take care of G++ cleanups. */
2653 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2654 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2655 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2656 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2657 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2658 /* If the equivalences are not to a constant, they may
2659 reference pseudos that no longer exist, so we can't
2661 && CONSTANT_P (XEXP (equiv1, 0))
2662 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2664 rtx s1 = single_set (i1);
2665 rtx s2 = single_set (i2);
2666 if (s1 != 0 && s2 != 0
2667 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2669 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2670 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2671 if (! rtx_renumbered_equal_p (p1, p2))
2673 else if (apply_change_group ())
2678 /* Insns fail to match; cross jumping is limited to the following
2682 /* Don't allow the insn after a compare to be shared by
2683 cross-jumping unless the compare is also shared.
2684 Here, if either of these non-matching insns is a compare,
2685 exclude the following insn from possible cross-jumping. */
2686 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2687 last1 = afterlast1, last2 = afterlast2, ++minimum;
2690 /* If cross-jumping here will feed a jump-around-jump
2691 optimization, this jump won't cost extra, so reduce
2693 if (GET_CODE (i1) == JUMP_INSN
2695 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2701 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2703 /* Ok, this insn is potentially includable in a cross-jump here. */
2704 afterlast1 = last1, afterlast2 = last2;
2705 last1 = i1, last2 = i2, --minimum;
2709 if (minimum <= 0 && last1 != 0 && last1 != e1)
2710 *f1 = last1, *f2 = last2;
2714 do_cross_jump (insn, newjpos, newlpos)
2715 rtx insn, newjpos, newlpos;
2717 /* Find an existing label at this point
2718 or make a new one if there is none. */
2719 register rtx label = get_label_before (newlpos);
2721 /* Make the same jump insn jump to the new point. */
2722 if (GET_CODE (PATTERN (insn)) == RETURN)
2724 /* Remove from jump chain of returns. */
2725 delete_from_jump_chain (insn);
2726 /* Change the insn. */
2727 PATTERN (insn) = gen_jump (label);
2728 INSN_CODE (insn) = -1;
2729 JUMP_LABEL (insn) = label;
2730 LABEL_NUSES (label)++;
2731 /* Add to new the jump chain. */
2732 if (INSN_UID (label) < max_jump_chain
2733 && INSN_UID (insn) < max_jump_chain)
2735 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2736 jump_chain[INSN_UID (label)] = insn;
2740 redirect_jump (insn, label);
2742 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2743 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2744 the NEWJPOS stream. */
2746 while (newjpos != insn)
2750 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2751 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2752 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2753 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2754 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2755 remove_note (newlpos, lnote);
2757 delete_insn (newjpos);
2758 newjpos = next_real_insn (newjpos);
2759 newlpos = next_real_insn (newlpos);
2763 /* Return the label before INSN, or put a new label there. */
2766 get_label_before (insn)
2771 /* Find an existing label at this point
2772 or make a new one if there is none. */
2773 label = prev_nonnote_insn (insn);
2775 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2777 rtx prev = PREV_INSN (insn);
2779 label = gen_label_rtx ();
2780 emit_label_after (label, prev);
2781 LABEL_NUSES (label) = 0;
2786 /* Return the label after INSN, or put a new label there. */
2789 get_label_after (insn)
2794 /* Find an existing label at this point
2795 or make a new one if there is none. */
2796 label = next_nonnote_insn (insn);
2798 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2800 label = gen_label_rtx ();
2801 emit_label_after (label, insn);
2802 LABEL_NUSES (label) = 0;
2807 /* Return 1 if INSN is a jump that jumps to right after TARGET
2808 only on the condition that TARGET itself would drop through.
2809 Assumes that TARGET is a conditional jump. */
2812 jump_back_p (insn, target)
2816 enum rtx_code codei, codet;
2818 if (simplejump_p (insn) || ! condjump_p (insn)
2819 || simplejump_p (target)
2820 || target != prev_real_insn (JUMP_LABEL (insn)))
2823 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2824 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2826 codei = GET_CODE (cinsn);
2827 codet = GET_CODE (ctarget);
2829 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2831 if (! can_reverse_comparison_p (cinsn, insn))
2833 codei = reverse_condition (codei);
2836 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2838 if (! can_reverse_comparison_p (ctarget, target))
2840 codet = reverse_condition (codet);
2843 return (codei == codet
2844 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2845 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2848 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2849 return non-zero if it is safe to reverse this comparison. It is if our
2850 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2851 this is known to be an integer comparison. */
2854 can_reverse_comparison_p (comparison, insn)
2860 /* If this is not actually a comparison, we can't reverse it. */
2861 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2864 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2865 /* If this is an NE comparison, it is safe to reverse it to an EQ
2866 comparison and vice versa, even for floating point. If no operands
2867 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2868 always false and NE is always true, so the reversal is also valid. */
2870 || GET_CODE (comparison) == NE
2871 || GET_CODE (comparison) == EQ)
2874 arg0 = XEXP (comparison, 0);
2876 /* Make sure ARG0 is one of the actual objects being compared. If we
2877 can't do this, we can't be sure the comparison can be reversed.
2879 Handle cc0 and a MODE_CC register. */
2880 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2886 rtx prev = prev_nonnote_insn (insn);
2887 rtx set = single_set (prev);
2889 if (set == 0 || SET_DEST (set) != arg0)
2892 arg0 = SET_SRC (set);
2894 if (GET_CODE (arg0) == COMPARE)
2895 arg0 = XEXP (arg0, 0);
2898 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2899 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2900 return (GET_CODE (arg0) == CONST_INT
2901 || (GET_MODE (arg0) != VOIDmode
2902 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2903 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2906 /* Given an rtx-code for a comparison, return the code
2907 for the negated comparison.
2908 WATCH OUT! reverse_condition is not safe to use on a jump
2909 that might be acting on the results of an IEEE floating point comparison,
2910 because of the special treatment of non-signaling nans in comparisons.
2911 Use can_reverse_comparison_p to be sure. */
2914 reverse_condition (code)
2955 /* Similar, but return the code when two operands of a comparison are swapped.
2956 This IS safe for IEEE floating-point. */
2959 swap_condition (code)
2998 /* Given a comparison CODE, return the corresponding unsigned comparison.
2999 If CODE is an equality comparison or already an unsigned comparison,
3000 CODE is returned. */
3003 unsigned_condition (code)
3033 /* Similarly, return the signed version of a comparison. */
3036 signed_condition (code)
3066 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3067 truth of CODE1 implies the truth of CODE2. */
3070 comparison_dominates_p (code1, code2)
3071 enum rtx_code code1, code2;
3079 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3084 if (code2 == LE || code2 == NE)
3089 if (code2 == GE || code2 == NE)
3094 if (code2 == LEU || code2 == NE)
3099 if (code2 == GEU || code2 == NE)
3110 /* Return 1 if INSN is an unconditional jump and nothing else. */
3116 return (GET_CODE (insn) == JUMP_INSN
3117 && GET_CODE (PATTERN (insn)) == SET
3118 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3119 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3122 /* Return nonzero if INSN is a (possibly) conditional jump
3123 and nothing more. */
3129 register rtx x = PATTERN (insn);
3130 if (GET_CODE (x) != SET)
3132 if (GET_CODE (SET_DEST (x)) != PC)
3134 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3136 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3138 if (XEXP (SET_SRC (x), 2) == pc_rtx
3139 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3140 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3142 if (XEXP (SET_SRC (x), 1) == pc_rtx
3143 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3144 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3149 /* Return nonzero if INSN is a (possibly) conditional jump
3150 and nothing more. */
3153 condjump_in_parallel_p (insn)
3156 register rtx x = PATTERN (insn);
3158 if (GET_CODE (x) != PARALLEL)
3161 x = XVECEXP (x, 0, 0);
3163 if (GET_CODE (x) != SET)
3165 if (GET_CODE (SET_DEST (x)) != PC)
3167 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3169 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3171 if (XEXP (SET_SRC (x), 2) == pc_rtx
3172 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3173 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3175 if (XEXP (SET_SRC (x), 1) == pc_rtx
3176 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3177 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3182 /* Return 1 if X is an RTX that does nothing but set the condition codes
3183 and CLOBBER or USE registers.
3184 Return -1 if X does explicitly set the condition codes,
3185 but also does other things. */
3192 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3194 if (GET_CODE (x) == PARALLEL)
3198 int other_things = 0;
3199 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3201 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3202 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3204 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3207 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3215 /* Follow any unconditional jump at LABEL;
3216 return the ultimate label reached by any such chain of jumps.
3217 If LABEL is not followed by a jump, return LABEL.
3218 If the chain loops or we can't find end, return LABEL,
3219 since that tells caller to avoid changing the insn.
3221 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3222 a USE or CLOBBER. */
3225 follow_jumps (label)
3230 register rtx value = label;
3235 && (insn = next_active_insn (value)) != 0
3236 && GET_CODE (insn) == JUMP_INSN
3237 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3238 || GET_CODE (PATTERN (insn)) == RETURN)
3239 && (next = NEXT_INSN (insn))
3240 && GET_CODE (next) == BARRIER);
3243 /* Don't chain through the insn that jumps into a loop
3244 from outside the loop,
3245 since that would create multiple loop entry jumps
3246 and prevent loop optimization. */
3248 if (!reload_completed)
3249 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3250 if (GET_CODE (tem) == NOTE
3251 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3252 /* ??? Optional. Disables some optimizations, but makes
3253 gcov output more accurate with -O. */
3254 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3257 /* If we have found a cycle, make the insn jump to itself. */
3258 if (JUMP_LABEL (insn) == label)
3261 tem = next_active_insn (JUMP_LABEL (insn));
3262 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3263 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3266 value = JUMP_LABEL (insn);
3273 /* Assuming that field IDX of X is a vector of label_refs,
3274 replace each of them by the ultimate label reached by it.
3275 Return nonzero if a change is made.
3276 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3279 tension_vector_labels (x, idx)
3285 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3287 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3288 register rtx nlabel = follow_jumps (olabel);
3289 if (nlabel && nlabel != olabel)
3291 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3292 ++LABEL_NUSES (nlabel);
3293 if (--LABEL_NUSES (olabel) == 0)
3294 delete_insn (olabel);
3301 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3302 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3303 in INSN, then store one of them in JUMP_LABEL (INSN).
3304 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3305 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3306 Also, when there are consecutive labels, canonicalize on the last of them.
3308 Note that two labels separated by a loop-beginning note
3309 must be kept distinct if we have not yet done loop-optimization,
3310 because the gap between them is where loop-optimize
3311 will want to move invariant code to. CROSS_JUMP tells us
3312 that loop-optimization is done with.
3314 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3315 two labels distinct if they are separated by only USE or CLOBBER insns. */
3318 mark_jump_label (x, insn, cross_jump)
3323 register RTX_CODE code = GET_CODE (x);
3341 /* If this is a constant-pool reference, see if it is a label. */
3342 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3343 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3344 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3349 rtx label = XEXP (x, 0);
3354 if (GET_CODE (label) != CODE_LABEL)
3357 /* Ignore references to labels of containing functions. */
3358 if (LABEL_REF_NONLOCAL_P (x))
3361 /* If there are other labels following this one,
3362 replace it with the last of the consecutive labels. */
3363 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3365 if (GET_CODE (next) == CODE_LABEL)
3367 else if (cross_jump && GET_CODE (next) == INSN
3368 && (GET_CODE (PATTERN (next)) == USE
3369 || GET_CODE (PATTERN (next)) == CLOBBER))
3371 else if (GET_CODE (next) != NOTE)
3373 else if (! cross_jump
3374 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3375 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3376 /* ??? Optional. Disables some optimizations, but
3377 makes gcov output more accurate with -O. */
3378 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3382 XEXP (x, 0) = label;
3383 if (! insn || ! INSN_DELETED_P (insn))
3384 ++LABEL_NUSES (label);
3388 if (GET_CODE (insn) == JUMP_INSN)
3389 JUMP_LABEL (insn) = label;
3391 /* If we've changed OLABEL and we had a REG_LABEL note
3392 for it, update it as well. */
3393 else if (label != olabel
3394 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3395 XEXP (note, 0) = label;
3397 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3399 else if (! find_reg_note (insn, REG_LABEL, label))
3401 /* This code used to ignore labels which refered to dispatch
3402 tables to avoid flow.c generating worse code.
3404 However, in the presense of global optimizations like
3405 gcse which call find_basic_blocks without calling
3406 life_analysis, not recording such labels will lead
3407 to compiler aborts because of inconsistencies in the
3408 flow graph. So we go ahead and record the label.
3410 It may also be the case that the optimization argument
3411 is no longer valid because of the more accurate cfg
3412 we build in find_basic_blocks -- it no longer pessimizes
3413 code when it finds a REG_LABEL note. */
3414 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
3421 /* Do walk the labels in a vector, but not the first operand of an
3422 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3425 if (! INSN_DELETED_P (insn))
3427 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3429 for (i = 0; i < XVECLEN (x, eltnum); i++)
3430 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3438 fmt = GET_RTX_FORMAT (code);
3439 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3442 mark_jump_label (XEXP (x, i), insn, cross_jump);
3443 else if (fmt[i] == 'E')
3446 for (j = 0; j < XVECLEN (x, i); j++)
3447 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3452 /* If all INSN does is set the pc, delete it,
3453 and delete the insn that set the condition codes for it
3454 if that's what the previous thing was. */
3460 register rtx set = single_set (insn);
3462 if (set && GET_CODE (SET_DEST (set)) == PC)
3463 delete_computation (insn);
3466 /* Delete INSN and recursively delete insns that compute values used only
3467 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3468 If we are running before flow.c, we need do nothing since flow.c will
3469 delete dead code. We also can't know if the registers being used are
3470 dead or not at this point.
3472 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3473 nothing other than set a register that dies in this insn, we can delete
3476 On machines with CC0, if CC0 is used in this insn, we may be able to
3477 delete the insn that set it. */
3480 delete_computation (insn)
3486 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3488 rtx prev = prev_nonnote_insn (insn);
3489 /* We assume that at this stage
3490 CC's are always set explicitly
3491 and always immediately before the jump that
3492 will use them. So if the previous insn
3493 exists to set the CC's, delete it
3494 (unless it performs auto-increments, etc.). */
3495 if (prev && GET_CODE (prev) == INSN
3496 && sets_cc0_p (PATTERN (prev)))
3498 if (sets_cc0_p (PATTERN (prev)) > 0
3499 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3500 delete_computation (prev);
3502 /* Otherwise, show that cc0 won't be used. */
3503 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
3504 cc0_rtx, REG_NOTES (prev));
3509 for (note = REG_NOTES (insn); note; note = next)
3513 next = XEXP (note, 1);
3515 if (REG_NOTE_KIND (note) != REG_DEAD
3516 /* Verify that the REG_NOTE is legitimate. */
3517 || GET_CODE (XEXP (note, 0)) != REG)
3520 for (our_prev = prev_nonnote_insn (insn);
3521 our_prev && GET_CODE (our_prev) == INSN;
3522 our_prev = prev_nonnote_insn (our_prev))
3524 /* If we reach a SEQUENCE, it is too complex to try to
3525 do anything with it, so give up. */
3526 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3529 if (GET_CODE (PATTERN (our_prev)) == USE
3530 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3531 /* reorg creates USEs that look like this. We leave them
3532 alone because reorg needs them for its own purposes. */
3535 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3537 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3540 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3542 /* If we find a SET of something else, we can't
3547 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3549 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3551 if (GET_CODE (part) == SET
3552 && SET_DEST (part) != XEXP (note, 0))
3556 if (i == XVECLEN (PATTERN (our_prev), 0))
3557 delete_computation (our_prev);
3559 else if (GET_CODE (PATTERN (our_prev)) == SET
3560 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3561 delete_computation (our_prev);
3566 /* If OUR_PREV references the register that dies here, it is an
3567 additional use. Hence any prior SET isn't dead. However, this
3568 insn becomes the new place for the REG_DEAD note. */
3569 if (reg_overlap_mentioned_p (XEXP (note, 0),
3570 PATTERN (our_prev)))
3572 XEXP (note, 1) = REG_NOTES (our_prev);
3573 REG_NOTES (our_prev) = note;
3582 /* Delete insn INSN from the chain of insns and update label ref counts.
3583 May delete some following insns as a consequence; may even delete
3584 a label elsewhere and insns that follow it.
3586 Returns the first insn after INSN that was not deleted. */
3592 register rtx next = NEXT_INSN (insn);
3593 register rtx prev = PREV_INSN (insn);
3594 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3595 register int dont_really_delete = 0;
3597 while (next && INSN_DELETED_P (next))
3598 next = NEXT_INSN (next);
3600 /* This insn is already deleted => return first following nondeleted. */
3601 if (INSN_DELETED_P (insn))
3604 /* Don't delete user-declared labels. Convert them to special NOTEs
3606 if (was_code_label && LABEL_NAME (insn) != 0
3607 && optimize && ! dont_really_delete)
3609 PUT_CODE (insn, NOTE);
3610 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3611 NOTE_SOURCE_FILE (insn) = 0;
3612 dont_really_delete = 1;
3615 /* Mark this insn as deleted. */
3616 INSN_DELETED_P (insn) = 1;
3618 /* If this is an unconditional jump, delete it from the jump chain. */
3619 if (simplejump_p (insn))
3620 delete_from_jump_chain (insn);
3622 /* If instruction is followed by a barrier,
3623 delete the barrier too. */
3625 if (next != 0 && GET_CODE (next) == BARRIER)
3627 INSN_DELETED_P (next) = 1;
3628 next = NEXT_INSN (next);
3631 /* Patch out INSN (and the barrier if any) */
3633 if (optimize && ! dont_really_delete)
3637 NEXT_INSN (prev) = next;
3638 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3639 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3640 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3645 PREV_INSN (next) = prev;
3646 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3647 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3650 if (prev && NEXT_INSN (prev) == 0)
3651 set_last_insn (prev);
3654 /* If deleting a jump, decrement the count of the label,
3655 and delete the label if it is now unused. */
3657 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3658 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3660 /* This can delete NEXT or PREV,
3661 either directly if NEXT is JUMP_LABEL (INSN),
3662 or indirectly through more levels of jumps. */
3663 delete_insn (JUMP_LABEL (insn));
3664 /* I feel a little doubtful about this loop,
3665 but I see no clean and sure alternative way
3666 to find the first insn after INSN that is not now deleted.
3667 I hope this works. */
3668 while (next && INSN_DELETED_P (next))
3669 next = NEXT_INSN (next);
3673 /* Likewise if we're deleting a dispatch table. */
3675 if (GET_CODE (insn) == JUMP_INSN
3676 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3677 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3679 rtx pat = PATTERN (insn);
3680 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3681 int len = XVECLEN (pat, diff_vec_p);
3683 for (i = 0; i < len; i++)
3684 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3685 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3686 while (next && INSN_DELETED_P (next))
3687 next = NEXT_INSN (next);
3691 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3692 prev = PREV_INSN (prev);
3694 /* If INSN was a label and a dispatch table follows it,
3695 delete the dispatch table. The tablejump must have gone already.
3696 It isn't useful to fall through into a table. */
3699 && NEXT_INSN (insn) != 0
3700 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3701 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3702 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3703 next = delete_insn (NEXT_INSN (insn));
3705 /* If INSN was a label, delete insns following it if now unreachable. */
3707 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3709 register RTX_CODE code;
3711 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3712 || code == NOTE || code == BARRIER
3713 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3716 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3717 next = NEXT_INSN (next);
3718 /* Keep going past other deleted labels to delete what follows. */
3719 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3720 next = NEXT_INSN (next);
3722 /* Note: if this deletes a jump, it can cause more
3723 deletion of unreachable code, after a different label.
3724 As long as the value from this recursive call is correct,
3725 this invocation functions correctly. */
3726 next = delete_insn (next);
3733 /* Advance from INSN till reaching something not deleted
3734 then return that. May return INSN itself. */
3737 next_nondeleted_insn (insn)
3740 while (INSN_DELETED_P (insn))
3741 insn = NEXT_INSN (insn);
3745 /* Delete a range of insns from FROM to TO, inclusive.
3746 This is for the sake of peephole optimization, so assume
3747 that whatever these insns do will still be done by a new
3748 peephole insn that will replace them. */
3751 delete_for_peephole (from, to)
3752 register rtx from, to;
3754 register rtx insn = from;
3758 register rtx next = NEXT_INSN (insn);
3759 register rtx prev = PREV_INSN (insn);
3761 if (GET_CODE (insn) != NOTE)
3763 INSN_DELETED_P (insn) = 1;
3765 /* Patch this insn out of the chain. */
3766 /* We don't do this all at once, because we
3767 must preserve all NOTEs. */
3769 NEXT_INSN (prev) = next;
3772 PREV_INSN (next) = prev;
3780 /* Note that if TO is an unconditional jump
3781 we *do not* delete the BARRIER that follows,
3782 since the peephole that replaces this sequence
3783 is also an unconditional jump in that case. */
3786 /* Invert the condition of the jump JUMP, and make it jump
3787 to label NLABEL instead of where it jumps now. */
3790 invert_jump (jump, nlabel)
3793 /* We have to either invert the condition and change the label or
3794 do neither. Either operation could fail. We first try to invert
3795 the jump. If that succeeds, we try changing the label. If that fails,
3796 we invert the jump back to what it was. */
3798 if (! invert_exp (PATTERN (jump), jump))
3801 if (redirect_jump (jump, nlabel))
3803 if (flag_branch_probabilities)
3805 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
3807 /* An inverted jump means that a probability taken becomes a
3808 probability not taken. Subtract the branch probability from the
3809 probability base to convert it back to a taken probability.
3810 (We don't flip the probability on a branch that's never taken. */
3811 if (note && XINT (XEXP (note, 0), 0) >= 0)
3812 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
3818 if (! invert_exp (PATTERN (jump), jump))
3819 /* This should just be putting it back the way it was. */
3825 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3827 Return 1 if we can do so, 0 if we cannot find a way to do so that
3828 matches a pattern. */
3831 invert_exp (x, insn)
3835 register RTX_CODE code;
3839 code = GET_CODE (x);
3841 if (code == IF_THEN_ELSE)
3843 register rtx comp = XEXP (x, 0);
3846 /* We can do this in two ways: The preferable way, which can only
3847 be done if this is not an integer comparison, is to reverse
3848 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3849 of the IF_THEN_ELSE. If we can't do either, fail. */
3851 if (can_reverse_comparison_p (comp, insn)
3852 && validate_change (insn, &XEXP (x, 0),
3853 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
3854 GET_MODE (comp), XEXP (comp, 0),
3855 XEXP (comp, 1)), 0))
3859 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3860 validate_change (insn, &XEXP (x, 2), tem, 1);
3861 return apply_change_group ();
3864 fmt = GET_RTX_FORMAT (code);
3865 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3868 if (! invert_exp (XEXP (x, i), insn))
3873 for (j = 0; j < XVECLEN (x, i); j++)
3874 if (!invert_exp (XVECEXP (x, i, j), insn))
3882 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3883 If the old jump target label is unused as a result,
3884 it and the code following it may be deleted.
3886 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3889 The return value will be 1 if the change was made, 0 if it wasn't (this
3890 can only occur for NLABEL == 0). */
3893 redirect_jump (jump, nlabel)
3896 register rtx olabel = JUMP_LABEL (jump);
3898 if (nlabel == olabel)
3901 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3904 /* If this is an unconditional branch, delete it from the jump_chain of
3905 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3906 have UID's in range and JUMP_CHAIN is valid). */
3907 if (jump_chain && (simplejump_p (jump)
3908 || GET_CODE (PATTERN (jump)) == RETURN))
3910 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3912 delete_from_jump_chain (jump);
3913 if (label_index < max_jump_chain
3914 && INSN_UID (jump) < max_jump_chain)
3916 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3917 jump_chain[label_index] = jump;
3921 JUMP_LABEL (jump) = nlabel;
3923 ++LABEL_NUSES (nlabel);
3925 if (olabel && --LABEL_NUSES (olabel) == 0)
3926 delete_insn (olabel);
3931 /* Delete the instruction JUMP from any jump chain it might be on. */
3934 delete_from_jump_chain (jump)
3938 rtx olabel = JUMP_LABEL (jump);
3940 /* Handle unconditional jumps. */
3941 if (jump_chain && olabel != 0
3942 && INSN_UID (olabel) < max_jump_chain
3943 && simplejump_p (jump))
3944 index = INSN_UID (olabel);
3945 /* Handle return insns. */
3946 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3950 if (jump_chain[index] == jump)
3951 jump_chain[index] = jump_chain[INSN_UID (jump)];
3956 for (insn = jump_chain[index];
3958 insn = jump_chain[INSN_UID (insn)])
3959 if (jump_chain[INSN_UID (insn)] == jump)
3961 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3967 /* If NLABEL is nonzero, throughout the rtx at LOC,
3968 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3969 zero, alter (RETURN) to (LABEL_REF NLABEL).
3971 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3972 validity with validate_change. Convert (set (pc) (label_ref olabel))
3975 Return 0 if we found a change we would like to make but it is invalid.
3976 Otherwise, return 1. */
3979 redirect_exp (loc, olabel, nlabel, insn)
3984 register rtx x = *loc;
3985 register RTX_CODE code = GET_CODE (x);
3989 if (code == LABEL_REF)
3991 if (XEXP (x, 0) == olabel)
3994 XEXP (x, 0) = nlabel;
3996 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4000 else if (code == RETURN && olabel == 0)
4002 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
4003 if (loc == &PATTERN (insn))
4004 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4005 return validate_change (insn, loc, x, 0);
4008 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4009 && GET_CODE (SET_SRC (x)) == LABEL_REF
4010 && XEXP (SET_SRC (x), 0) == olabel)
4011 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4013 fmt = GET_RTX_FORMAT (code);
4014 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4017 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4022 for (j = 0; j < XVECLEN (x, i); j++)
4023 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4031 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4033 If the old jump target label (before the dispatch table) becomes unused,
4034 it and the dispatch table may be deleted. In that case, find the insn
4035 before the jump references that label and delete it and logical successors
4039 redirect_tablejump (jump, nlabel)
4042 register rtx olabel = JUMP_LABEL (jump);
4044 /* Add this jump to the jump_chain of NLABEL. */
4045 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4046 && INSN_UID (jump) < max_jump_chain)
4048 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4049 jump_chain[INSN_UID (nlabel)] = jump;
4052 PATTERN (jump) = gen_jump (nlabel);
4053 JUMP_LABEL (jump) = nlabel;
4054 ++LABEL_NUSES (nlabel);
4055 INSN_CODE (jump) = -1;
4057 if (--LABEL_NUSES (olabel) == 0)
4059 delete_labelref_insn (jump, olabel, 0);
4060 delete_insn (olabel);
4064 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4065 If we found one, delete it and then delete this insn if DELETE_THIS is
4066 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4069 delete_labelref_insn (insn, label, delete_this)
4076 if (GET_CODE (insn) != NOTE
4077 && reg_mentioned_p (label, PATTERN (insn)))
4088 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4089 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4103 /* Like rtx_equal_p except that it considers two REGs as equal
4104 if they renumber to the same value and considers two commutative
4105 operations to be the same if the order of the operands has been
4109 rtx_renumbered_equal_p (x, y)
4113 register RTX_CODE code = GET_CODE (x);
4119 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4120 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4121 && GET_CODE (SUBREG_REG (y)) == REG)))
4123 int reg_x = -1, reg_y = -1;
4124 int word_x = 0, word_y = 0;
4126 if (GET_MODE (x) != GET_MODE (y))
4129 /* If we haven't done any renumbering, don't
4130 make any assumptions. */
4131 if (reg_renumber == 0)
4132 return rtx_equal_p (x, y);
4136 reg_x = REGNO (SUBREG_REG (x));
4137 word_x = SUBREG_WORD (x);
4139 if (reg_renumber[reg_x] >= 0)
4141 reg_x = reg_renumber[reg_x] + word_x;
4149 if (reg_renumber[reg_x] >= 0)
4150 reg_x = reg_renumber[reg_x];
4153 if (GET_CODE (y) == SUBREG)
4155 reg_y = REGNO (SUBREG_REG (y));
4156 word_y = SUBREG_WORD (y);
4158 if (reg_renumber[reg_y] >= 0)
4160 reg_y = reg_renumber[reg_y];
4168 if (reg_renumber[reg_y] >= 0)
4169 reg_y = reg_renumber[reg_y];
4172 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4175 /* Now we have disposed of all the cases
4176 in which different rtx codes can match. */
4177 if (code != GET_CODE (y))
4189 return INTVAL (x) == INTVAL (y);
4192 /* We can't assume nonlocal labels have their following insns yet. */
4193 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4194 return XEXP (x, 0) == XEXP (y, 0);
4196 /* Two label-refs are equivalent if they point at labels
4197 in the same position in the instruction stream. */
4198 return (next_real_insn (XEXP (x, 0))
4199 == next_real_insn (XEXP (y, 0)));
4202 return XSTR (x, 0) == XSTR (y, 0);
4208 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4210 if (GET_MODE (x) != GET_MODE (y))
4213 /* For commutative operations, the RTX match if the operand match in any
4214 order. Also handle the simple binary and unary cases without a loop. */
4215 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4216 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4217 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4218 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4219 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4220 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4221 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4222 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4223 else if (GET_RTX_CLASS (code) == '1')
4224 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4226 /* Compare the elements. If any pair of corresponding elements
4227 fail to match, return 0 for the whole things. */
4229 fmt = GET_RTX_FORMAT (code);
4230 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4236 if (XWINT (x, i) != XWINT (y, i))
4241 if (XINT (x, i) != XINT (y, i))
4246 if (strcmp (XSTR (x, i), XSTR (y, i)))
4251 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4256 if (XEXP (x, i) != XEXP (y, i))
4263 if (XVECLEN (x, i) != XVECLEN (y, i))
4265 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4266 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4277 /* If X is a hard register or equivalent to one or a subregister of one,
4278 return the hard register number. If X is a pseudo register that was not
4279 assigned a hard register, return the pseudo register number. Otherwise,
4280 return -1. Any rtx is valid for X. */
4286 if (GET_CODE (x) == REG)
4288 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4289 return reg_renumber[REGNO (x)];
4292 if (GET_CODE (x) == SUBREG)
4294 int base = true_regnum (SUBREG_REG (x));
4295 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4296 return SUBREG_WORD (x) + base;
4301 /* Optimize code of the form:
4303 for (x = a[i]; x; ...)
4305 for (x = a[i]; x; ...)
4309 Loop optimize will change the above code into
4313 { ...; if (! (x = ...)) break; }
4316 { ...; if (! (x = ...)) break; }
4319 In general, if the first test fails, the program can branch
4320 directly to `foo' and skip the second try which is doomed to fail.
4321 We run this after loop optimization and before flow analysis. */
4323 /* When comparing the insn patterns, we track the fact that different
4324 pseudo-register numbers may have been used in each computation.
4325 The following array stores an equivalence -- same_regs[I] == J means
4326 that pseudo register I was used in the first set of tests in a context
4327 where J was used in the second set. We also count the number of such
4328 pending equivalences. If nonzero, the expressions really aren't the
4331 static int *same_regs;
4333 static int num_same_regs;
4335 /* Track any registers modified between the target of the first jump and
4336 the second jump. They never compare equal. */
4338 static char *modified_regs;
4340 /* Record if memory was modified. */
4342 static int modified_mem;
4344 /* Called via note_stores on each insn between the target of the first
4345 branch and the second branch. It marks any changed registers. */
4348 mark_modified_reg (dest, x)
4354 if (GET_CODE (dest) == SUBREG)
4355 dest = SUBREG_REG (dest);
4357 if (GET_CODE (dest) == MEM)
4360 if (GET_CODE (dest) != REG)
4363 regno = REGNO (dest);
4364 if (regno >= FIRST_PSEUDO_REGISTER)
4365 modified_regs[regno] = 1;
4367 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4368 modified_regs[regno + i] = 1;
4371 /* F is the first insn in the chain of insns. */
4374 thread_jumps (f, max_reg, flag_before_loop)
4377 int flag_before_loop;
4379 /* Basic algorithm is to find a conditional branch,
4380 the label it may branch to, and the branch after
4381 that label. If the two branches test the same condition,
4382 walk back from both branch paths until the insn patterns
4383 differ, or code labels are hit. If we make it back to
4384 the target of the first branch, then we know that the first branch
4385 will either always succeed or always fail depending on the relative
4386 senses of the two branches. So adjust the first branch accordingly
4389 rtx label, b1, b2, t1, t2;
4390 enum rtx_code code1, code2;
4391 rtx b1op0, b1op1, b2op0, b2op1;
4396 /* Allocate register tables and quick-reset table. */
4397 modified_regs = (char *) alloca (max_reg * sizeof (char));
4398 same_regs = (int *) alloca (max_reg * sizeof (int));
4399 all_reset = (int *) alloca (max_reg * sizeof (int));
4400 for (i = 0; i < max_reg; i++)
4407 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4409 /* Get to a candidate branch insn. */
4410 if (GET_CODE (b1) != JUMP_INSN
4411 || ! condjump_p (b1) || simplejump_p (b1)
4412 || JUMP_LABEL (b1) == 0)
4415 bzero (modified_regs, max_reg * sizeof (char));
4418 bcopy ((char *) all_reset, (char *) same_regs,
4419 max_reg * sizeof (int));
4422 label = JUMP_LABEL (b1);
4424 /* Look for a branch after the target. Record any registers and
4425 memory modified between the target and the branch. Stop when we
4426 get to a label since we can't know what was changed there. */
4427 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4429 if (GET_CODE (b2) == CODE_LABEL)
4432 else if (GET_CODE (b2) == JUMP_INSN)
4434 /* If this is an unconditional jump and is the only use of
4435 its target label, we can follow it. */
4436 if (simplejump_p (b2)
4437 && JUMP_LABEL (b2) != 0
4438 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4440 b2 = JUMP_LABEL (b2);
4447 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4450 if (GET_CODE (b2) == CALL_INSN)
4453 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4454 if (call_used_regs[i] && ! fixed_regs[i]
4455 && i != STACK_POINTER_REGNUM
4456 && i != FRAME_POINTER_REGNUM
4457 && i != HARD_FRAME_POINTER_REGNUM
4458 && i != ARG_POINTER_REGNUM)
4459 modified_regs[i] = 1;
4462 note_stores (PATTERN (b2), mark_modified_reg);
4465 /* Check the next candidate branch insn from the label
4468 || GET_CODE (b2) != JUMP_INSN
4470 || ! condjump_p (b2)
4471 || simplejump_p (b2))
4474 /* Get the comparison codes and operands, reversing the
4475 codes if appropriate. If we don't have comparison codes,
4476 we can't do anything. */
4477 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4478 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4479 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4480 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4481 code1 = reverse_condition (code1);
4483 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4484 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4485 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4486 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4487 code2 = reverse_condition (code2);
4489 /* If they test the same things and knowing that B1 branches
4490 tells us whether or not B2 branches, check if we
4491 can thread the branch. */
4492 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4493 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4494 && (comparison_dominates_p (code1, code2)
4495 || (comparison_dominates_p (code1, reverse_condition (code2))
4496 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
4500 t1 = prev_nonnote_insn (b1);
4501 t2 = prev_nonnote_insn (b2);
4503 while (t1 != 0 && t2 != 0)
4507 /* We have reached the target of the first branch.
4508 If there are no pending register equivalents,
4509 we know that this branch will either always
4510 succeed (if the senses of the two branches are
4511 the same) or always fail (if not). */
4514 if (num_same_regs != 0)
4517 if (comparison_dominates_p (code1, code2))
4518 new_label = JUMP_LABEL (b2);
4520 new_label = get_label_after (b2);
4522 if (JUMP_LABEL (b1) != new_label)
4524 rtx prev = PREV_INSN (new_label);
4526 if (flag_before_loop
4527 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4529 /* Don't thread to the loop label. If a loop
4530 label is reused, loop optimization will
4531 be disabled for that loop. */
4532 new_label = gen_label_rtx ();
4533 emit_label_after (new_label, PREV_INSN (prev));
4535 changed |= redirect_jump (b1, new_label);
4540 /* If either of these is not a normal insn (it might be
4541 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4542 have already been skipped above.) Similarly, fail
4543 if the insns are different. */
4544 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4545 || recog_memoized (t1) != recog_memoized (t2)
4546 || ! rtx_equal_for_thread_p (PATTERN (t1),
4550 t1 = prev_nonnote_insn (t1);
4551 t2 = prev_nonnote_insn (t2);
4558 /* This is like RTX_EQUAL_P except that it knows about our handling of
4559 possibly equivalent registers and knows to consider volatile and
4560 modified objects as not equal.
4562 YINSN is the insn containing Y. */
4565 rtx_equal_for_thread_p (x, y, yinsn)
4571 register enum rtx_code code;
4574 code = GET_CODE (x);
4575 /* Rtx's of different codes cannot be equal. */
4576 if (code != GET_CODE (y))
4579 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4580 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4582 if (GET_MODE (x) != GET_MODE (y))
4585 /* For floating-point, consider everything unequal. This is a bit
4586 pessimistic, but this pass would only rarely do anything for FP
4588 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4589 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
4592 /* For commutative operations, the RTX match if the operand match in any
4593 order. Also handle the simple binary and unary cases without a loop. */
4594 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4595 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4596 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4597 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4598 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4599 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4600 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4601 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4602 else if (GET_RTX_CLASS (code) == '1')
4603 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4605 /* Handle special-cases first. */
4609 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4612 /* If neither is user variable or hard register, check for possible
4614 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4615 || REGNO (x) < FIRST_PSEUDO_REGISTER
4616 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4619 if (same_regs[REGNO (x)] == -1)
4621 same_regs[REGNO (x)] = REGNO (y);
4624 /* If this is the first time we are seeing a register on the `Y'
4625 side, see if it is the last use. If not, we can't thread the
4626 jump, so mark it as not equivalent. */
4627 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4633 return (same_regs[REGNO (x)] == REGNO (y));
4638 /* If memory modified or either volatile, not equivalent.
4639 Else, check address. */
4640 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4643 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4646 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4652 /* Cancel a pending `same_regs' if setting equivalenced registers.
4653 Then process source. */
4654 if (GET_CODE (SET_DEST (x)) == REG
4655 && GET_CODE (SET_DEST (y)) == REG)
4657 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4659 same_regs[REGNO (SET_DEST (x))] = -1;
4662 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4666 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4669 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4672 return XEXP (x, 0) == XEXP (y, 0);
4675 return XSTR (x, 0) == XSTR (y, 0);
4684 fmt = GET_RTX_FORMAT (code);
4685 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4690 if (XWINT (x, i) != XWINT (y, i))
4696 if (XINT (x, i) != XINT (y, i))
4702 /* Two vectors must have the same length. */
4703 if (XVECLEN (x, i) != XVECLEN (y, i))
4706 /* And the corresponding elements must match. */
4707 for (j = 0; j < XVECLEN (x, i); j++)
4708 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4709 XVECEXP (y, i, j), yinsn) == 0)
4714 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4720 if (strcmp (XSTR (x, i), XSTR (y, i)))
4725 /* These are just backpointers, so they don't matter. */
4731 /* It is believed that rtx's at this level will never
4732 contain anything but integers and other rtx's,
4733 except for within LABEL_REFs and SYMBOL_REFs. */
4742 /* Return the insn that NEW can be safely inserted in front of starting at
4743 the jump insn INSN. Return 0 if it is not safe to do this jump
4744 optimization. Note that NEW must contain a single set. */
4747 find_insert_position (insn, new)
4754 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
4755 if (GET_CODE (PATTERN (new)) != PARALLEL)
4758 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
4759 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
4760 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
4767 /* There is a good chance that the previous insn PREV sets the thing
4768 being clobbered (often the CC in a hard reg). If PREV does not
4769 use what NEW sets, we can insert NEW before PREV. */
4771 prev = prev_active_insn (insn);
4772 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
4773 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
4774 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
4776 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
4780 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;