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));
122 static rtx find_insert_position PROTO((rtx, rtx));
124 static int rtx_unsafe_p PROTO((rtx));
126 /* Delete no-op jumps and optimize jumps to jumps
127 and jumps around jumps.
128 Delete unused labels and unreachable code.
130 If CROSS_JUMP is 1, detect matching code
131 before a jump and its destination and unify them.
132 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
134 If NOOP_MOVES is nonzero, delete no-op move insns.
136 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
137 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
139 If `optimize' is zero, don't change any code,
140 just determine whether control drops off the end of the function.
141 This case occurs when we have -W and not -O.
142 It works because `delete_insn' checks the value of `optimize'
143 and refrains from actually deleting when that is 0. */
146 jump_optimize (f, cross_jump, noop_moves, after_regscan)
152 register rtx insn, next, note;
158 cross_jump_death_matters = (cross_jump == 2);
160 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
161 notes whose labels don't occur in the insn any more. */
163 for (insn = f; insn; insn = NEXT_INSN (insn))
165 if (GET_CODE (insn) == CODE_LABEL)
166 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
167 else if (GET_CODE (insn) == JUMP_INSN)
168 JUMP_LABEL (insn) = 0;
169 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
170 for (note = REG_NOTES (insn); note; note = next)
172 next = XEXP (note, 1);
173 if (REG_NOTE_KIND (note) == REG_LABEL
174 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
175 remove_note (insn, note);
178 if (INSN_UID (insn) > max_uid)
179 max_uid = INSN_UID (insn);
184 /* Delete insns following barriers, up to next label. */
186 for (insn = f; insn;)
188 if (GET_CODE (insn) == BARRIER)
190 insn = NEXT_INSN (insn);
191 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
193 if (GET_CODE (insn) == NOTE
194 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
195 insn = NEXT_INSN (insn);
197 insn = delete_insn (insn);
199 /* INSN is now the code_label. */
202 insn = NEXT_INSN (insn);
205 /* Leave some extra room for labels and duplicate exit test insns
207 max_jump_chain = max_uid * 14 / 10;
208 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
209 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
211 /* Mark the label each jump jumps to.
212 Combine consecutive labels, and count uses of labels.
214 For each label, make a chain (using `jump_chain')
215 of all the *unconditional* jumps that jump to it;
216 also make a chain of all returns. */
218 for (insn = f; insn; insn = NEXT_INSN (insn))
219 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
221 mark_jump_label (PATTERN (insn), insn, cross_jump);
222 if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
224 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
226 jump_chain[INSN_UID (insn)]
227 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
228 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
230 if (GET_CODE (PATTERN (insn)) == RETURN)
232 jump_chain[INSN_UID (insn)] = jump_chain[0];
233 jump_chain[0] = insn;
238 /* Keep track of labels used from static data;
239 they cannot ever be deleted. */
241 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
242 LABEL_NUSES (XEXP (insn, 0))++;
244 check_exception_handler_labels ();
246 /* Keep track of labels used for marking handlers for exception
247 regions; they cannot usually be deleted. */
249 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
250 LABEL_NUSES (XEXP (insn, 0))++;
252 exception_optimize ();
254 /* Delete all labels already not referenced.
255 Also find the last insn. */
258 for (insn = f; insn; )
260 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
261 insn = delete_insn (insn);
265 insn = NEXT_INSN (insn);
271 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
272 If so record that this function can drop off the end. */
278 /* One label can follow the end-note: the return label. */
279 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
280 /* Ordinary insns can follow it if returning a structure. */
281 || GET_CODE (insn) == INSN
282 /* If machine uses explicit RETURN insns, no epilogue,
283 then one of them follows the note. */
284 || (GET_CODE (insn) == JUMP_INSN
285 && GET_CODE (PATTERN (insn)) == RETURN)
286 /* A barrier can follow the return insn. */
287 || GET_CODE (insn) == BARRIER
288 /* Other kinds of notes can follow also. */
289 || (GET_CODE (insn) == NOTE
290 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
291 insn = PREV_INSN (insn);
294 /* Report if control can fall through at the end of the function. */
295 if (insn && GET_CODE (insn) == NOTE
296 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
297 && ! INSN_DELETED_P (insn))
300 /* Zero the "deleted" flag of all the "deleted" insns. */
301 for (insn = f; insn; insn = NEXT_INSN (insn))
302 INSN_DELETED_P (insn) = 0;
309 /* If we fall through to the epilogue, see if we can insert a RETURN insn
310 in front of it. If the machine allows it at this point (we might be
311 after reload for a leaf routine), it will improve optimization for it
313 insn = get_last_insn ();
314 while (insn && GET_CODE (insn) == NOTE)
315 insn = PREV_INSN (insn);
317 if (insn && GET_CODE (insn) != BARRIER)
319 emit_jump_insn (gen_return ());
326 for (insn = f; insn; )
328 next = NEXT_INSN (insn);
330 if (GET_CODE (insn) == INSN)
332 register rtx body = PATTERN (insn);
334 /* Combine stack_adjusts with following push_insns. */
336 if (GET_CODE (body) == SET
337 && SET_DEST (body) == stack_pointer_rtx
338 && GET_CODE (SET_SRC (body)) == PLUS
339 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
340 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
341 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
344 rtx stack_adjust_insn = insn;
345 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
346 int total_pushed = 0;
349 /* Find all successive push insns. */
351 /* Don't convert more than three pushes;
352 that starts adding too many displaced addresses
353 and the whole thing starts becoming a losing
358 p = next_nonnote_insn (p);
359 if (p == 0 || GET_CODE (p) != INSN)
362 if (GET_CODE (pbody) != SET)
364 dest = SET_DEST (pbody);
365 /* Allow a no-op move between the adjust and the push. */
366 if (GET_CODE (dest) == REG
367 && GET_CODE (SET_SRC (pbody)) == REG
368 && REGNO (dest) == REGNO (SET_SRC (pbody)))
370 if (! (GET_CODE (dest) == MEM
371 && GET_CODE (XEXP (dest, 0)) == POST_INC
372 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
375 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
376 > stack_adjust_amount)
378 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
381 /* Discard the amount pushed from the stack adjust;
382 maybe eliminate it entirely. */
383 if (total_pushed >= stack_adjust_amount)
385 delete_computation (stack_adjust_insn);
386 total_pushed = stack_adjust_amount;
389 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
390 = GEN_INT (stack_adjust_amount - total_pushed);
392 /* Change the appropriate push insns to ordinary stores. */
394 while (total_pushed > 0)
397 p = next_nonnote_insn (p);
398 if (GET_CODE (p) != INSN)
401 if (GET_CODE (pbody) == SET)
403 dest = SET_DEST (pbody);
404 if (! (GET_CODE (dest) == MEM
405 && GET_CODE (XEXP (dest, 0)) == POST_INC
406 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
408 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
409 /* If this push doesn't fully fit in the space
410 of the stack adjust that we deleted,
411 make another stack adjust here for what we
412 didn't use up. There should be peepholes
413 to recognize the resulting sequence of insns. */
414 if (total_pushed < 0)
416 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
417 GEN_INT (- total_pushed)),
422 = plus_constant (stack_pointer_rtx, total_pushed);
427 /* Detect and delete no-op move instructions
428 resulting from not allocating a parameter in a register. */
430 if (GET_CODE (body) == SET
431 && (SET_DEST (body) == SET_SRC (body)
432 || (GET_CODE (SET_DEST (body)) == MEM
433 && GET_CODE (SET_SRC (body)) == MEM
434 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
435 && ! (GET_CODE (SET_DEST (body)) == MEM
436 && MEM_VOLATILE_P (SET_DEST (body)))
437 && ! (GET_CODE (SET_SRC (body)) == MEM
438 && MEM_VOLATILE_P (SET_SRC (body))))
439 delete_computation (insn);
441 /* Detect and ignore no-op move instructions
442 resulting from smart or fortuitous register allocation. */
444 else if (GET_CODE (body) == SET)
446 int sreg = true_regnum (SET_SRC (body));
447 int dreg = true_regnum (SET_DEST (body));
449 if (sreg == dreg && sreg >= 0)
451 else if (sreg >= 0 && dreg >= 0)
454 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
455 sreg, NULL_PTR, dreg,
456 GET_MODE (SET_SRC (body)));
459 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
461 /* DREG may have been the target of a REG_DEAD note in
462 the insn which makes INSN redundant. If so, reorg
463 would still think it is dead. So search for such a
464 note and delete it if we find it. */
465 if (! find_regno_note (insn, REG_UNUSED, dreg))
466 for (trial = prev_nonnote_insn (insn);
467 trial && GET_CODE (trial) != CODE_LABEL;
468 trial = prev_nonnote_insn (trial))
469 if (find_regno_note (trial, REG_DEAD, dreg))
471 remove_death (dreg, trial);
474 #ifdef PRESERVE_DEATH_INFO_REGNO_P
475 /* Deleting insn could lose a death-note for SREG
476 so don't do it if final needs accurate
478 if (PRESERVE_DEATH_INFO_REGNO_P (sreg)
479 && (trial = find_regno_note (insn, REG_DEAD, sreg)))
481 /* Change this into a USE so that we won't emit
482 code for it, but still can keep the note. */
484 = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
485 INSN_CODE (insn) = -1;
486 /* Remove all reg notes but the REG_DEAD one. */
487 REG_NOTES (insn) = trial;
488 XEXP (trial, 1) = NULL_RTX;
495 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
496 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
498 GET_MODE (SET_DEST (body))))
500 /* This handles the case where we have two consecutive
501 assignments of the same constant to pseudos that didn't
502 get a hard reg. Each SET from the constant will be
503 converted into a SET of the spill register and an
504 output reload will be made following it. This produces
505 two loads of the same constant into the same spill
510 /* Look back for a death note for the first reg.
511 If there is one, it is no longer accurate. */
512 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
514 if ((GET_CODE (in_insn) == INSN
515 || GET_CODE (in_insn) == JUMP_INSN)
516 && find_regno_note (in_insn, REG_DEAD, dreg))
518 remove_death (dreg, in_insn);
521 in_insn = PREV_INSN (in_insn);
524 /* Delete the second load of the value. */
528 else if (GET_CODE (body) == PARALLEL)
530 /* If each part is a set between two identical registers or
531 a USE or CLOBBER, delete the insn. */
535 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
537 tem = XVECEXP (body, 0, i);
538 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
541 if (GET_CODE (tem) != SET
542 || (sreg = true_regnum (SET_SRC (tem))) < 0
543 || (dreg = true_regnum (SET_DEST (tem))) < 0
551 /* Also delete insns to store bit fields if they are no-ops. */
552 /* Not worth the hair to detect this in the big-endian case. */
553 else if (! BYTES_BIG_ENDIAN
554 && GET_CODE (body) == SET
555 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
556 && XEXP (SET_DEST (body), 2) == const0_rtx
557 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
558 && ! (GET_CODE (SET_SRC (body)) == MEM
559 && MEM_VOLATILE_P (SET_SRC (body))))
565 /* If we haven't yet gotten to reload and we have just run regscan,
566 delete any insn that sets a register that isn't used elsewhere.
567 This helps some of the optimizations below by having less insns
568 being jumped around. */
570 if (! reload_completed && after_regscan)
571 for (insn = f; insn; insn = next)
573 rtx set = single_set (insn);
575 next = NEXT_INSN (insn);
577 if (set && GET_CODE (SET_DEST (set)) == REG
578 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
579 && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
580 /* We use regno_last_note_uid so as not to delete the setting
581 of a reg that's used in notes. A subsequent optimization
582 might arrange to use that reg for real. */
583 && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
584 && ! side_effects_p (SET_SRC (set))
585 && ! find_reg_note (insn, REG_RETVAL, 0))
589 /* Now iterate optimizing jumps until nothing changes over one pass. */
595 for (insn = f; insn; insn = next)
598 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
600 int this_is_simplejump, this_is_condjump, reversep;
601 int this_is_condjump_in_parallel;
603 /* If NOT the first iteration, if this is the last jump pass
604 (just before final), do the special peephole optimizations.
605 Avoiding the first iteration gives ordinary jump opts
606 a chance to work before peephole opts. */
608 if (reload_completed && !first && !flag_no_peephole)
609 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
613 /* That could have deleted some insns after INSN, so check now
614 what the following insn is. */
616 next = NEXT_INSN (insn);
618 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
619 jump. Try to optimize by duplicating the loop exit test if so.
620 This is only safe immediately after regscan, because it uses
621 the values of regno_first_uid and regno_last_uid. */
622 if (after_regscan && GET_CODE (insn) == NOTE
623 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
624 && (temp1 = next_nonnote_insn (insn)) != 0
625 && simplejump_p (temp1))
627 temp = PREV_INSN (insn);
628 if (duplicate_loop_exit_test (insn))
631 next = NEXT_INSN (temp);
636 if (GET_CODE (insn) != JUMP_INSN)
639 this_is_simplejump = simplejump_p (insn);
640 this_is_condjump = condjump_p (insn);
641 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
643 /* Tension the labels in dispatch tables. */
645 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
646 changed |= tension_vector_labels (PATTERN (insn), 0);
647 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
648 changed |= tension_vector_labels (PATTERN (insn), 1);
650 /* If a dispatch table always goes to the same place,
651 get rid of it and replace the insn that uses it. */
653 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
654 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
657 rtx pat = PATTERN (insn);
658 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
659 int len = XVECLEN (pat, diff_vec_p);
660 rtx dispatch = prev_real_insn (insn);
662 for (i = 0; i < len; i++)
663 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
664 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
668 && GET_CODE (dispatch) == JUMP_INSN
669 && JUMP_LABEL (dispatch) != 0
670 /* Don't mess with a casesi insn. */
671 && !(GET_CODE (PATTERN (dispatch)) == SET
672 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
674 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
676 redirect_tablejump (dispatch,
677 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
682 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
684 /* If a jump references the end of the function, try to turn
685 it into a RETURN insn, possibly a conditional one. */
686 if (JUMP_LABEL (insn)
687 && (next_active_insn (JUMP_LABEL (insn)) == 0
688 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
690 changed |= redirect_jump (insn, NULL_RTX);
692 /* Detect jump to following insn. */
693 if (reallabelprev == insn && condjump_p (insn))
695 next = next_real_insn (JUMP_LABEL (insn));
701 /* If we have an unconditional jump preceded by a USE, try to put
702 the USE before the target and jump there. This simplifies many
703 of the optimizations below since we don't have to worry about
704 dealing with these USE insns. We only do this if the label
705 being branch to already has the identical USE or if code
706 never falls through to that label. */
708 if (this_is_simplejump
709 && (temp = prev_nonnote_insn (insn)) != 0
710 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
711 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
712 && (GET_CODE (temp1) == BARRIER
713 || (GET_CODE (temp1) == INSN
714 && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
715 /* Don't do this optimization if we have a loop containing only
716 the USE instruction, and the loop start label has a usage
717 count of 1. This is because we will redo this optimization
718 everytime through the outer loop, and jump opt will never
720 && ! ((temp2 = prev_nonnote_insn (temp)) != 0
721 && temp2 == JUMP_LABEL (insn)
722 && LABEL_NUSES (temp2) == 1))
724 if (GET_CODE (temp1) == BARRIER)
726 emit_insn_after (PATTERN (temp), temp1);
727 temp1 = NEXT_INSN (temp1);
731 redirect_jump (insn, get_label_before (temp1));
732 reallabelprev = prev_real_insn (temp1);
736 /* Simplify if (...) x = a; else x = b; by converting it
737 to x = b; if (...) x = a;
738 if B is sufficiently simple, the test doesn't involve X,
739 and nothing in the test modifies B or X.
741 If we have small register classes, we also can't do this if X
744 If the "x = b;" insn has any REG_NOTES, we don't do this because
745 of the possibility that we are running after CSE and there is a
746 REG_EQUAL note that is only valid if the branch has already been
747 taken. If we move the insn with the REG_EQUAL note, we may
748 fold the comparison to always be false in a later CSE pass.
749 (We could also delete the REG_NOTES when moving the insn, but it
750 seems simpler to not move it.) An exception is that we can move
751 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
752 value is the same as "b".
754 INSN is the branch over the `else' part.
758 TEMP to the jump insn preceding "x = a;"
760 TEMP2 to the insn that sets "x = b;"
761 TEMP3 to the insn that sets "x = a;"
762 TEMP4 to the set of "x = b"; */
764 if (this_is_simplejump
765 && (temp3 = prev_active_insn (insn)) != 0
766 && GET_CODE (temp3) == INSN
767 && (temp4 = single_set (temp3)) != 0
768 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
769 && (! SMALL_REGISTER_CLASSES
770 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
771 && (temp2 = next_active_insn (insn)) != 0
772 && GET_CODE (temp2) == INSN
773 && (temp4 = single_set (temp2)) != 0
774 && rtx_equal_p (SET_DEST (temp4), temp1)
775 && ! rtx_unsafe_p (SET_SRC (temp4))
776 && (REG_NOTES (temp2) == 0
777 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
778 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
779 && XEXP (REG_NOTES (temp2), 1) == 0
780 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
782 && (temp = prev_active_insn (temp3)) != 0
783 && condjump_p (temp) && ! simplejump_p (temp)
784 /* TEMP must skip over the "x = a;" insn */
785 && prev_real_insn (JUMP_LABEL (temp)) == insn
786 && no_labels_between_p (insn, JUMP_LABEL (temp))
787 /* There must be no other entries to the "x = b;" insn. */
788 && no_labels_between_p (JUMP_LABEL (temp), temp2)
789 /* INSN must either branch to the insn after TEMP2 or the insn
790 after TEMP2 must branch to the same place as INSN. */
791 && (reallabelprev == temp2
792 || ((temp5 = next_active_insn (temp2)) != 0
793 && simplejump_p (temp5)
794 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
796 /* The test expression, X, may be a complicated test with
797 multiple branches. See if we can find all the uses of
798 the label that TEMP branches to without hitting a CALL_INSN
799 or a jump to somewhere else. */
800 rtx target = JUMP_LABEL (temp);
801 int nuses = LABEL_NUSES (target);
807 /* Set P to the first jump insn that goes around "x = a;". */
808 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
810 if (GET_CODE (p) == JUMP_INSN)
812 if (condjump_p (p) && ! simplejump_p (p)
813 && JUMP_LABEL (p) == target)
822 else if (GET_CODE (p) == CALL_INSN)
827 /* We cannot insert anything between a set of cc and its use
828 so if P uses cc0, we must back up to the previous insn. */
829 q = prev_nonnote_insn (p);
830 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
831 && sets_cc0_p (PATTERN (q)))
838 /* If we found all the uses and there was no data conflict, we
839 can move the assignment unless we can branch into the middle
842 && no_labels_between_p (p, insn)
843 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
844 && ! reg_set_between_p (temp1, p, temp3)
845 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
846 || ! modified_between_p (SET_SRC (temp4), p, temp2)))
848 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
851 /* Set NEXT to an insn that we know won't go away. */
852 next = next_active_insn (insn);
854 /* Delete the jump around the set. Note that we must do
855 this before we redirect the test jumps so that it won't
856 delete the code immediately following the assignment
857 we moved (which might be a jump). */
861 /* We either have two consecutive labels or a jump to
862 a jump, so adjust all the JUMP_INSNs to branch to where
864 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
865 if (GET_CODE (p) == JUMP_INSN)
866 redirect_jump (p, target);
873 /* Simplify if (...) { x = a; goto l; } x = b; by converting it
874 to x = a; if (...) goto l; x = b;
875 if A is sufficiently simple, the test doesn't involve X,
876 and nothing in the test modifies A or X.
878 If we have small register classes, we also can't do this if X
881 If the "x = a;" insn has any REG_NOTES, we don't do this because
882 of the possibility that we are running after CSE and there is a
883 REG_EQUAL note that is only valid if the branch has already been
884 taken. If we move the insn with the REG_EQUAL note, we may
885 fold the comparison to always be false in a later CSE pass.
886 (We could also delete the REG_NOTES when moving the insn, but it
887 seems simpler to not move it.) An exception is that we can move
888 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
889 value is the same as "a".
895 TEMP to the jump insn preceding "x = a;"
897 TEMP2 to the insn that sets "x = b;"
898 TEMP3 to the insn that sets "x = a;"
899 TEMP4 to the set of "x = a"; */
901 if (this_is_simplejump
902 && (temp2 = next_active_insn (insn)) != 0
903 && GET_CODE (temp2) == INSN
904 && (temp4 = single_set (temp2)) != 0
905 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
906 && (! SMALL_REGISTER_CLASSES
907 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
908 && (temp3 = prev_active_insn (insn)) != 0
909 && GET_CODE (temp3) == INSN
910 && (temp4 = single_set (temp3)) != 0
911 && rtx_equal_p (SET_DEST (temp4), temp1)
912 && (GET_CODE (SET_SRC (temp4)) == REG
913 || GET_CODE (SET_SRC (temp4)) == SUBREG
914 || (GET_CODE (SET_SRC (temp4)) == MEM
915 && RTX_UNCHANGING_P (SET_SRC (temp4)))
916 || CONSTANT_P (SET_SRC (temp4)))
917 && (REG_NOTES (temp3) == 0
918 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
919 || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
920 && XEXP (REG_NOTES (temp3), 1) == 0
921 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
923 && (temp = prev_active_insn (temp3)) != 0
924 && condjump_p (temp) && ! simplejump_p (temp)
925 /* TEMP must skip over the "x = a;" insn */
926 && prev_real_insn (JUMP_LABEL (temp)) == insn
927 && no_labels_between_p (temp, insn))
929 rtx prev_label = JUMP_LABEL (temp);
930 rtx insert_after = prev_nonnote_insn (temp);
933 /* We cannot insert anything between a set of cc and its use. */
934 if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
935 && sets_cc0_p (PATTERN (insert_after)))
936 insert_after = prev_nonnote_insn (insert_after);
938 ++LABEL_NUSES (prev_label);
941 && no_labels_between_p (insert_after, temp)
942 && ! reg_referenced_between_p (temp1, insert_after, temp3)
943 && ! reg_referenced_between_p (temp1, temp3,
945 && ! reg_set_between_p (temp1, insert_after, temp)
946 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
947 || ! reg_set_between_p (SET_SRC (temp4),
949 && invert_jump (temp, JUMP_LABEL (insn)))
951 emit_insn_after_with_line_notes (PATTERN (temp3),
952 insert_after, temp3);
955 /* Set NEXT to an insn that we know won't go away. */
959 if (prev_label && --LABEL_NUSES (prev_label) == 0)
960 delete_insn (prev_label);
966 /* If we have if (...) x = exp; and branches are expensive,
967 EXP is a single insn, does not have any side effects, cannot
968 trap, and is not too costly, convert this to
969 t = exp; if (...) x = t;
971 Don't do this when we have CC0 because it is unlikely to help
972 and we'd need to worry about where to place the new insn and
973 the potential for conflicts. We also can't do this when we have
974 notes on the insn for the same reason as above.
978 TEMP to the "x = exp;" insn.
979 TEMP1 to the single set in the "x = exp; insn.
982 if (! reload_completed
983 && this_is_condjump && ! this_is_simplejump
985 && (temp = next_nonnote_insn (insn)) != 0
986 && GET_CODE (temp) == INSN
987 && REG_NOTES (temp) == 0
988 && (reallabelprev == temp
989 || ((temp2 = next_active_insn (temp)) != 0
990 && simplejump_p (temp2)
991 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
992 && (temp1 = single_set (temp)) != 0
993 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
994 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
995 && (! SMALL_REGISTER_CLASSES
996 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
997 && GET_CODE (SET_SRC (temp1)) != REG
998 && GET_CODE (SET_SRC (temp1)) != SUBREG
999 && GET_CODE (SET_SRC (temp1)) != CONST_INT
1000 && ! side_effects_p (SET_SRC (temp1))
1001 && ! may_trap_p (SET_SRC (temp1))
1002 && rtx_cost (SET_SRC (temp1), SET) < 10)
1004 rtx new = gen_reg_rtx (GET_MODE (temp2));
1006 if ((temp3 = find_insert_position (insn, temp))
1007 && validate_change (temp, &SET_DEST (temp1), new, 0))
1009 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1010 emit_insn_after_with_line_notes (PATTERN (temp),
1011 PREV_INSN (temp3), temp);
1013 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1017 /* Similarly, if it takes two insns to compute EXP but they
1018 have the same destination. Here TEMP3 will be the second
1019 insn and TEMP4 the SET from that insn. */
1021 if (! reload_completed
1022 && this_is_condjump && ! this_is_simplejump
1024 && (temp = next_nonnote_insn (insn)) != 0
1025 && GET_CODE (temp) == INSN
1026 && REG_NOTES (temp) == 0
1027 && (temp3 = next_nonnote_insn (temp)) != 0
1028 && GET_CODE (temp3) == INSN
1029 && REG_NOTES (temp3) == 0
1030 && (reallabelprev == temp3
1031 || ((temp2 = next_active_insn (temp3)) != 0
1032 && simplejump_p (temp2)
1033 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1034 && (temp1 = single_set (temp)) != 0
1035 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
1036 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1037 && (! SMALL_REGISTER_CLASSES
1038 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
1039 && ! side_effects_p (SET_SRC (temp1))
1040 && ! may_trap_p (SET_SRC (temp1))
1041 && rtx_cost (SET_SRC (temp1), SET) < 10
1042 && (temp4 = single_set (temp3)) != 0
1043 && rtx_equal_p (SET_DEST (temp4), temp2)
1044 && ! side_effects_p (SET_SRC (temp4))
1045 && ! may_trap_p (SET_SRC (temp4))
1046 && rtx_cost (SET_SRC (temp4), SET) < 10)
1048 rtx new = gen_reg_rtx (GET_MODE (temp2));
1050 if ((temp5 = find_insert_position (insn, temp))
1051 && (temp6 = find_insert_position (insn, temp3))
1052 && validate_change (temp, &SET_DEST (temp1), new, 0))
1054 /* Use the earliest of temp5 and temp6. */
1057 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1058 emit_insn_after_with_line_notes (PATTERN (temp),
1059 PREV_INSN (temp6), temp);
1060 emit_insn_after_with_line_notes
1061 (replace_rtx (PATTERN (temp3), temp2, new),
1062 PREV_INSN (temp6), temp3);
1064 delete_insn (temp3);
1065 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1069 /* Finally, handle the case where two insns are used to
1070 compute EXP but a temporary register is used. Here we must
1071 ensure that the temporary register is not used anywhere else. */
1073 if (! reload_completed
1075 && this_is_condjump && ! this_is_simplejump
1077 && (temp = next_nonnote_insn (insn)) != 0
1078 && GET_CODE (temp) == INSN
1079 && REG_NOTES (temp) == 0
1080 && (temp3 = next_nonnote_insn (temp)) != 0
1081 && GET_CODE (temp3) == INSN
1082 && REG_NOTES (temp3) == 0
1083 && (reallabelprev == temp3
1084 || ((temp2 = next_active_insn (temp3)) != 0
1085 && simplejump_p (temp2)
1086 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
1087 && (temp1 = single_set (temp)) != 0
1088 && (temp5 = SET_DEST (temp1),
1089 (GET_CODE (temp5) == REG
1090 || (GET_CODE (temp5) == SUBREG
1091 && (temp5 = SUBREG_REG (temp5),
1092 GET_CODE (temp5) == REG))))
1093 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
1094 && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
1095 && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
1096 && ! side_effects_p (SET_SRC (temp1))
1097 && ! may_trap_p (SET_SRC (temp1))
1098 && rtx_cost (SET_SRC (temp1), SET) < 10
1099 && (temp4 = single_set (temp3)) != 0
1100 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
1101 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
1102 && (! SMALL_REGISTER_CLASSES
1103 || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
1104 && rtx_equal_p (SET_DEST (temp4), temp2)
1105 && ! side_effects_p (SET_SRC (temp4))
1106 && ! may_trap_p (SET_SRC (temp4))
1107 && rtx_cost (SET_SRC (temp4), SET) < 10)
1109 rtx new = gen_reg_rtx (GET_MODE (temp2));
1111 if ((temp5 = find_insert_position (insn, temp))
1112 && (temp6 = find_insert_position (insn, temp3))
1113 && validate_change (temp3, &SET_DEST (temp4), new, 0))
1115 /* Use the earliest of temp5 and temp6. */
1118 next = emit_insn_after (gen_move_insn (temp2, new), insn);
1119 emit_insn_after_with_line_notes (PATTERN (temp),
1120 PREV_INSN (temp6), temp);
1121 emit_insn_after_with_line_notes (PATTERN (temp3),
1122 PREV_INSN (temp6), temp3);
1124 delete_insn (temp3);
1125 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
1128 #endif /* HAVE_cc0 */
1130 /* Try to use a conditional move (if the target has them), or a
1131 store-flag insn. The general case is:
1133 1) x = a; if (...) x = b; and
1136 If the jump would be faster, the machine should not have defined
1137 the movcc or scc insns!. These cases are often made by the
1138 previous optimization.
1140 The second case is treated as x = x; if (...) x = b;.
1142 INSN here is the jump around the store. We set:
1144 TEMP to the "x = b;" insn.
1147 TEMP3 to A (X in the second case).
1148 TEMP4 to the condition being tested.
1149 TEMP5 to the earliest insn used to find the condition. */
1151 if (/* We can't do this after reload has completed. */
1153 && this_is_condjump && ! this_is_simplejump
1154 /* Set TEMP to the "x = b;" insn. */
1155 && (temp = next_nonnote_insn (insn)) != 0
1156 && GET_CODE (temp) == INSN
1157 && GET_CODE (PATTERN (temp)) == SET
1158 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1159 && (! SMALL_REGISTER_CLASSES
1160 || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
1161 && ! rtx_unsafe_p (temp2 = SET_SRC (PATTERN (temp)))
1162 /* Allow either form, but prefer the former if both apply.
1163 There is no point in using the old value of TEMP1 if
1164 it is a register, since cse will alias them. It can
1165 lose if the old value were a hard register since CSE
1166 won't replace hard registers. Avoid using TEMP3 if
1167 small register classes and it is a hard register. */
1168 && (((temp3 = reg_set_last (temp1, insn)) != 0
1169 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
1170 && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
1171 /* Make the latter case look like x = x; if (...) x = b; */
1172 || (temp3 = temp1, 1))
1173 /* INSN must either branch to the insn after TEMP or the insn
1174 after TEMP must branch to the same place as INSN. */
1175 && (reallabelprev == temp
1176 || ((temp4 = next_active_insn (temp)) != 0
1177 && simplejump_p (temp4)
1178 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1179 && (temp4 = get_condition (insn, &temp5)) != 0
1180 /* We must be comparing objects whose modes imply the size.
1181 We could handle BLKmode if (1) emit_store_flag could
1182 and (2) we could find the size reliably. */
1183 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1184 /* Even if branches are cheap, the store_flag optimization
1185 can win when the operation to be performed can be
1186 expressed directly. */
1188 /* If the previous insn sets CC0 and something else, we can't
1189 do this since we are going to delete that insn. */
1191 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1192 && GET_CODE (temp6) == INSN
1193 && (sets_cc0_p (PATTERN (temp6)) == -1
1194 || (sets_cc0_p (PATTERN (temp6)) == 1
1195 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1199 #ifdef HAVE_conditional_move
1200 /* First try a conditional move. */
1202 enum rtx_code code = GET_CODE (temp4);
1204 rtx cond0, cond1, aval, bval;
1207 /* Copy the compared variables into cond0 and cond1, so that
1208 any side effects performed in or after the old comparison,
1209 will not affect our compare which will come later. */
1210 /* ??? Is it possible to just use the comparison in the jump
1211 insn? After all, we're going to delete it. We'd have
1212 to modify emit_conditional_move to take a comparison rtx
1213 instead or write a new function. */
1214 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1215 /* We want the target to be able to simplify comparisons with
1216 zero (and maybe other constants as well), so don't create
1217 pseudos for them. There's no need to either. */
1218 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1219 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1220 cond1 = XEXP (temp4, 1);
1222 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1228 target = emit_conditional_move (var, code,
1229 cond0, cond1, VOIDmode,
1230 aval, bval, GET_MODE (var),
1231 (code == LTU || code == GEU
1232 || code == LEU || code == GTU));
1238 /* Save the conditional move sequence but don't emit it
1239 yet. On some machines, like the alpha, it is possible
1240 that temp5 == insn, so next generate the sequence that
1241 saves the compared values and then emit both
1242 sequences ensuring seq1 occurs before seq2. */
1243 seq2 = get_insns ();
1246 /* Now that we can't fail, generate the copy insns that
1247 preserve the compared values. */
1249 emit_move_insn (cond0, XEXP (temp4, 0));
1250 if (cond1 != XEXP (temp4, 1))
1251 emit_move_insn (cond1, XEXP (temp4, 1));
1252 seq1 = get_insns ();
1255 emit_insns_before (seq1, temp5);
1256 /* Insert conditional move after insn, to be sure that
1257 the jump and a possible compare won't be separated */
1258 emit_insns_after (seq2, insn);
1260 /* ??? We can also delete the insn that sets X to A.
1261 Flow will do it too though. */
1263 next = NEXT_INSN (insn);
1273 /* That didn't work, try a store-flag insn.
1275 We further divide the cases into:
1277 1) x = a; if (...) x = b; and either A or B is zero,
1278 2) if (...) x = 0; and jumps are expensive,
1279 3) x = a; if (...) x = b; and A and B are constants where all
1280 the set bits in A are also set in B and jumps are expensive,
1281 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1283 5) if (...) x = b; if jumps are even more expensive. */
1285 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1286 && ((GET_CODE (temp3) == CONST_INT)
1287 /* Make the latter case look like
1288 x = x; if (...) x = 0; */
1291 && temp2 == const0_rtx)
1292 || BRANCH_COST >= 3)))
1293 /* If B is zero, OK; if A is zero, can only do (1) if we
1294 can reverse the condition. See if (3) applies possibly
1295 by reversing the condition. Prefer reversing to (4) when
1296 branches are very expensive. */
1297 && (((BRANCH_COST >= 2
1298 || STORE_FLAG_VALUE == -1
1299 || (STORE_FLAG_VALUE == 1
1300 /* Check that the mask is a power of two,
1301 so that it can probably be generated
1303 && exact_log2 (INTVAL (temp3)) >= 0))
1304 && (reversep = 0, temp2 == const0_rtx))
1305 || ((BRANCH_COST >= 2
1306 || STORE_FLAG_VALUE == -1
1307 || (STORE_FLAG_VALUE == 1
1308 && exact_log2 (INTVAL (temp2)) >= 0))
1309 && temp3 == const0_rtx
1310 && (reversep = can_reverse_comparison_p (temp4, insn)))
1311 || (BRANCH_COST >= 2
1312 && GET_CODE (temp2) == CONST_INT
1313 && GET_CODE (temp3) == CONST_INT
1314 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1315 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1316 && (reversep = can_reverse_comparison_p (temp4,
1318 || BRANCH_COST >= 3)
1321 enum rtx_code code = GET_CODE (temp4);
1322 rtx uval, cval, var = temp1;
1326 /* If necessary, reverse the condition. */
1328 code = reverse_condition (code), uval = temp2, cval = temp3;
1330 uval = temp3, cval = temp2;
1332 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1333 is the constant 1, it is best to just compute the result
1334 directly. If UVAL is constant and STORE_FLAG_VALUE
1335 includes all of its bits, it is best to compute the flag
1336 value unnormalized and `and' it with UVAL. Otherwise,
1337 normalize to -1 and `and' with UVAL. */
1338 normalizep = (cval != const0_rtx ? -1
1339 : (uval == const1_rtx ? 1
1340 : (GET_CODE (uval) == CONST_INT
1341 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1344 /* We will be putting the store-flag insn immediately in
1345 front of the comparison that was originally being done,
1346 so we know all the variables in TEMP4 will be valid.
1347 However, this might be in front of the assignment of
1348 A to VAR. If it is, it would clobber the store-flag
1349 we will be emitting.
1351 Therefore, emit into a temporary which will be copied to
1352 VAR immediately after TEMP. */
1355 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1356 XEXP (temp4, 0), XEXP (temp4, 1),
1358 (code == LTU || code == LEU
1359 || code == GEU || code == GTU),
1369 /* Put the store-flag insns in front of the first insn
1370 used to compute the condition to ensure that we
1371 use the same values of them as the current
1372 comparison. However, the remainder of the insns we
1373 generate will be placed directly in front of the
1374 jump insn, in case any of the pseudos we use
1375 are modified earlier. */
1377 emit_insns_before (seq, temp5);
1381 /* Both CVAL and UVAL are non-zero. */
1382 if (cval != const0_rtx && uval != const0_rtx)
1386 tem1 = expand_and (uval, target, NULL_RTX);
1387 if (GET_CODE (cval) == CONST_INT
1388 && GET_CODE (uval) == CONST_INT
1389 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1393 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1394 target, NULL_RTX, 0);
1395 tem2 = expand_and (cval, tem2,
1396 (GET_CODE (tem2) == REG
1400 /* If we usually make new pseudos, do so here. This
1401 turns out to help machines that have conditional
1403 /* ??? Conditional moves have already been handled.
1404 This may be obsolete. */
1406 if (flag_expensive_optimizations)
1409 target = expand_binop (GET_MODE (var), ior_optab,
1413 else if (normalizep != 1)
1415 /* We know that either CVAL or UVAL is zero. If
1416 UVAL is zero, negate TARGET and `and' with CVAL.
1417 Otherwise, `and' with UVAL. */
1418 if (uval == const0_rtx)
1420 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1421 target, NULL_RTX, 0);
1425 target = expand_and (uval, target,
1426 (GET_CODE (target) == REG
1427 && ! preserve_subexpressions_p ()
1428 ? target : NULL_RTX));
1431 emit_move_insn (var, target);
1435 /* If INSN uses CC0, we must not separate it from the
1436 insn that sets cc0. */
1437 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1438 before = prev_nonnote_insn (before);
1440 emit_insns_before (seq, before);
1443 next = NEXT_INSN (insn);
1453 /* If branches are expensive, convert
1454 if (foo) bar++; to bar += (foo != 0);
1455 and similarly for "bar--;"
1457 INSN is the conditional branch around the arithmetic. We set:
1459 TEMP is the arithmetic insn.
1460 TEMP1 is the SET doing the arithmetic.
1461 TEMP2 is the operand being incremented or decremented.
1462 TEMP3 to the condition being tested.
1463 TEMP4 to the earliest insn used to find the condition. */
1465 if ((BRANCH_COST >= 2
1473 && ! reload_completed
1474 && this_is_condjump && ! this_is_simplejump
1475 && (temp = next_nonnote_insn (insn)) != 0
1476 && (temp1 = single_set (temp)) != 0
1477 && (temp2 = SET_DEST (temp1),
1478 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1479 && GET_CODE (SET_SRC (temp1)) == PLUS
1480 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1481 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1482 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1483 && ! side_effects_p (temp2)
1484 && ! may_trap_p (temp2)
1485 /* INSN must either branch to the insn after TEMP or the insn
1486 after TEMP must branch to the same place as INSN. */
1487 && (reallabelprev == temp
1488 || ((temp3 = next_active_insn (temp)) != 0
1489 && simplejump_p (temp3)
1490 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1491 && (temp3 = get_condition (insn, &temp4)) != 0
1492 /* We must be comparing objects whose modes imply the size.
1493 We could handle BLKmode if (1) emit_store_flag could
1494 and (2) we could find the size reliably. */
1495 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1496 && can_reverse_comparison_p (temp3, insn))
1498 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1499 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1503 /* It must be the case that TEMP2 is not modified in the range
1504 [TEMP4, INSN). The one exception we make is if the insn
1505 before INSN sets TEMP2 to something which is also unchanged
1506 in that range. In that case, we can move the initialization
1507 into our sequence. */
1509 if ((temp5 = prev_active_insn (insn)) != 0
1510 && no_labels_between_p (temp5, insn)
1511 && GET_CODE (temp5) == INSN
1512 && (temp6 = single_set (temp5)) != 0
1513 && rtx_equal_p (temp2, SET_DEST (temp6))
1514 && (CONSTANT_P (SET_SRC (temp6))
1515 || GET_CODE (SET_SRC (temp6)) == REG
1516 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1518 emit_insn (PATTERN (temp5));
1520 init = SET_SRC (temp6);
1523 if (CONSTANT_P (init)
1524 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1525 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1526 XEXP (temp3, 0), XEXP (temp3, 1),
1528 (code == LTU || code == LEU
1529 || code == GTU || code == GEU), 1);
1531 /* If we can do the store-flag, do the addition or
1535 target = expand_binop (GET_MODE (temp2),
1536 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1537 ? add_optab : sub_optab),
1538 temp2, target, temp2, 0, OPTAB_WIDEN);
1542 /* Put the result back in temp2 in case it isn't already.
1543 Then replace the jump, possible a CC0-setting insn in
1544 front of the jump, and TEMP, with the sequence we have
1547 if (target != temp2)
1548 emit_move_insn (temp2, target);
1553 emit_insns_before (seq, temp4);
1557 delete_insn (init_insn);
1559 next = NEXT_INSN (insn);
1561 delete_insn (prev_nonnote_insn (insn));
1571 /* Simplify if (...) x = 1; else {...} if (x) ...
1572 We recognize this case scanning backwards as well.
1574 TEMP is the assignment to x;
1575 TEMP1 is the label at the head of the second if. */
1576 /* ?? This should call get_condition to find the values being
1577 compared, instead of looking for a COMPARE insn when HAVE_cc0
1578 is not defined. This would allow it to work on the m88k. */
1579 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1580 is not defined and the condition is tested by a separate compare
1581 insn. This is because the code below assumes that the result
1582 of the compare dies in the following branch.
1584 Not only that, but there might be other insns between the
1585 compare and branch whose results are live. Those insns need
1588 A way to fix this is to move the insns at JUMP_LABEL (insn)
1589 to before INSN. If we are running before flow, they will
1590 be deleted if they aren't needed. But this doesn't work
1593 This is really a special-case of jump threading, anyway. The
1594 right thing to do is to replace this and jump threading with
1595 much simpler code in cse.
1597 This code has been turned off in the non-cc0 case in the
1601 else if (this_is_simplejump
1602 /* Safe to skip USE and CLOBBER insns here
1603 since they will not be deleted. */
1604 && (temp = prev_active_insn (insn))
1605 && no_labels_between_p (temp, insn)
1606 && GET_CODE (temp) == INSN
1607 && GET_CODE (PATTERN (temp)) == SET
1608 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1609 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1610 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1611 /* If we find that the next value tested is `x'
1612 (TEMP1 is the insn where this happens), win. */
1613 && GET_CODE (temp1) == INSN
1614 && GET_CODE (PATTERN (temp1)) == SET
1616 /* Does temp1 `tst' the value of x? */
1617 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1618 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1619 && (temp1 = next_nonnote_insn (temp1))
1621 /* Does temp1 compare the value of x against zero? */
1622 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1623 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1624 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1625 == SET_DEST (PATTERN (temp)))
1626 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1627 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1629 && condjump_p (temp1))
1631 /* Get the if_then_else from the condjump. */
1632 rtx choice = SET_SRC (PATTERN (temp1));
1633 if (GET_CODE (choice) == IF_THEN_ELSE)
1635 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1636 rtx val = SET_SRC (PATTERN (temp));
1638 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1642 if (cond == const_true_rtx)
1643 ultimate = XEXP (choice, 1);
1644 else if (cond == const0_rtx)
1645 ultimate = XEXP (choice, 2);
1649 if (ultimate == pc_rtx)
1650 ultimate = get_label_after (temp1);
1651 else if (ultimate && GET_CODE (ultimate) != RETURN)
1652 ultimate = XEXP (ultimate, 0);
1654 if (ultimate && JUMP_LABEL(insn) != ultimate)
1655 changed |= redirect_jump (insn, ultimate);
1661 /* @@ This needs a bit of work before it will be right.
1663 Any type of comparison can be accepted for the first and
1664 second compare. When rewriting the first jump, we must
1665 compute the what conditions can reach label3, and use the
1666 appropriate code. We can not simply reverse/swap the code
1667 of the first jump. In some cases, the second jump must be
1671 < == converts to > ==
1672 < != converts to == >
1675 If the code is written to only accept an '==' test for the second
1676 compare, then all that needs to be done is to swap the condition
1677 of the first branch.
1679 It is questionable whether we want this optimization anyways,
1680 since if the user wrote code like this because he/she knew that
1681 the jump to label1 is taken most of the time, then rewriting
1682 this gives slower code. */
1683 /* @@ This should call get_condition to find the values being
1684 compared, instead of looking for a COMPARE insn when HAVE_cc0
1685 is not defined. This would allow it to work on the m88k. */
1686 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1687 is not defined and the condition is tested by a separate compare
1688 insn. This is because the code below assumes that the result
1689 of the compare dies in the following branch. */
1691 /* Simplify test a ~= b
1705 where ~= is an inequality, e.g. >, and ~~= is the swapped
1708 We recognize this case scanning backwards.
1710 TEMP is the conditional jump to `label2';
1711 TEMP1 is the test for `a == b';
1712 TEMP2 is the conditional jump to `label1';
1713 TEMP3 is the test for `a ~= b'. */
1714 else if (this_is_simplejump
1715 && (temp = prev_active_insn (insn))
1716 && no_labels_between_p (temp, insn)
1717 && condjump_p (temp)
1718 && (temp1 = prev_active_insn (temp))
1719 && no_labels_between_p (temp1, temp)
1720 && GET_CODE (temp1) == INSN
1721 && GET_CODE (PATTERN (temp1)) == SET
1723 && sets_cc0_p (PATTERN (temp1)) == 1
1725 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1726 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1727 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1729 && (temp2 = prev_active_insn (temp1))
1730 && no_labels_between_p (temp2, temp1)
1731 && condjump_p (temp2)
1732 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1733 && (temp3 = prev_active_insn (temp2))
1734 && no_labels_between_p (temp3, temp2)
1735 && GET_CODE (PATTERN (temp3)) == SET
1736 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1737 SET_DEST (PATTERN (temp1)))
1738 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1739 SET_SRC (PATTERN (temp3)))
1740 && ! inequality_comparisons_p (PATTERN (temp))
1741 && inequality_comparisons_p (PATTERN (temp2)))
1743 rtx fallthrough_label = JUMP_LABEL (temp2);
1745 ++LABEL_NUSES (fallthrough_label);
1746 if (swap_jump (temp2, JUMP_LABEL (insn)))
1752 if (--LABEL_NUSES (fallthrough_label) == 0)
1753 delete_insn (fallthrough_label);
1756 /* Simplify if (...) {... x = 1;} if (x) ...
1758 We recognize this case backwards.
1760 TEMP is the test of `x';
1761 TEMP1 is the assignment to `x' at the end of the
1762 previous statement. */
1763 /* @@ This should call get_condition to find the values being
1764 compared, instead of looking for a COMPARE insn when HAVE_cc0
1765 is not defined. This would allow it to work on the m88k. */
1766 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1767 is not defined and the condition is tested by a separate compare
1768 insn. This is because the code below assumes that the result
1769 of the compare dies in the following branch. */
1771 /* ??? This has to be turned off. The problem is that the
1772 unconditional jump might indirectly end up branching to the
1773 label between TEMP1 and TEMP. We can't detect this, in general,
1774 since it may become a jump to there after further optimizations.
1775 If that jump is done, it will be deleted, so we will retry
1776 this optimization in the next pass, thus an infinite loop.
1778 The present code prevents this by putting the jump after the
1779 label, but this is not logically correct. */
1781 else if (this_is_condjump
1782 /* Safe to skip USE and CLOBBER insns here
1783 since they will not be deleted. */
1784 && (temp = prev_active_insn (insn))
1785 && no_labels_between_p (temp, insn)
1786 && GET_CODE (temp) == INSN
1787 && GET_CODE (PATTERN (temp)) == SET
1789 && sets_cc0_p (PATTERN (temp)) == 1
1790 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1792 /* Temp must be a compare insn, we can not accept a register
1793 to register move here, since it may not be simply a
1795 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1796 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1797 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1798 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1799 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1801 /* May skip USE or CLOBBER insns here
1802 for checking for opportunity, since we
1803 take care of them later. */
1804 && (temp1 = prev_active_insn (temp))
1805 && GET_CODE (temp1) == INSN
1806 && GET_CODE (PATTERN (temp1)) == SET
1808 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1810 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1811 == SET_DEST (PATTERN (temp1)))
1813 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1814 /* If this isn't true, cse will do the job. */
1815 && ! no_labels_between_p (temp1, temp))
1817 /* Get the if_then_else from the condjump. */
1818 rtx choice = SET_SRC (PATTERN (insn));
1819 if (GET_CODE (choice) == IF_THEN_ELSE
1820 && (GET_CODE (XEXP (choice, 0)) == EQ
1821 || GET_CODE (XEXP (choice, 0)) == NE))
1823 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1828 /* Get the place that condjump will jump to
1829 if it is reached from here. */
1830 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1832 ultimate = XEXP (choice, 1);
1834 ultimate = XEXP (choice, 2);
1835 /* Get it as a CODE_LABEL. */
1836 if (ultimate == pc_rtx)
1837 ultimate = get_label_after (insn);
1839 /* Get the label out of the LABEL_REF. */
1840 ultimate = XEXP (ultimate, 0);
1842 /* Insert the jump immediately before TEMP, specifically
1843 after the label that is between TEMP1 and TEMP. */
1844 last_insn = PREV_INSN (temp);
1846 /* If we would be branching to the next insn, the jump
1847 would immediately be deleted and the re-inserted in
1848 a subsequent pass over the code. So don't do anything
1850 if (next_active_insn (last_insn)
1851 != next_active_insn (ultimate))
1853 emit_barrier_after (last_insn);
1854 p = emit_jump_insn_after (gen_jump (ultimate),
1856 JUMP_LABEL (p) = ultimate;
1857 ++LABEL_NUSES (ultimate);
1858 if (INSN_UID (ultimate) < max_jump_chain
1859 && INSN_CODE (p) < max_jump_chain)
1861 jump_chain[INSN_UID (p)]
1862 = jump_chain[INSN_UID (ultimate)];
1863 jump_chain[INSN_UID (ultimate)] = p;
1871 /* Detect a conditional jump going to the same place
1872 as an immediately following unconditional jump. */
1873 else if (this_is_condjump
1874 && (temp = next_active_insn (insn)) != 0
1875 && simplejump_p (temp)
1876 && (next_active_insn (JUMP_LABEL (insn))
1877 == next_active_insn (JUMP_LABEL (temp))))
1881 /* ??? Optional. Disables some optimizations, but makes
1882 gcov output more accurate with -O. */
1883 if (flag_test_coverage && !reload_completed)
1884 for (tem = insn; tem != temp; tem = NEXT_INSN (tem))
1885 if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0)
1895 /* Detect a conditional jump jumping over an unconditional jump. */
1897 else if ((this_is_condjump || this_is_condjump_in_parallel)
1898 && ! this_is_simplejump
1899 && reallabelprev != 0
1900 && GET_CODE (reallabelprev) == JUMP_INSN
1901 && prev_active_insn (reallabelprev) == insn
1902 && no_labels_between_p (insn, reallabelprev)
1903 && simplejump_p (reallabelprev))
1905 /* When we invert the unconditional jump, we will be
1906 decrementing the usage count of its old label.
1907 Make sure that we don't delete it now because that
1908 might cause the following code to be deleted. */
1909 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1910 rtx prev_label = JUMP_LABEL (insn);
1913 ++LABEL_NUSES (prev_label);
1915 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1917 /* It is very likely that if there are USE insns before
1918 this jump, they hold REG_DEAD notes. These REG_DEAD
1919 notes are no longer valid due to this optimization,
1920 and will cause the life-analysis that following passes
1921 (notably delayed-branch scheduling) to think that
1922 these registers are dead when they are not.
1924 To prevent this trouble, we just remove the USE insns
1925 from the insn chain. */
1927 while (prev_uses && GET_CODE (prev_uses) == INSN
1928 && GET_CODE (PATTERN (prev_uses)) == USE)
1930 rtx useless = prev_uses;
1931 prev_uses = prev_nonnote_insn (prev_uses);
1932 delete_insn (useless);
1935 delete_insn (reallabelprev);
1940 /* We can now safely delete the label if it is unreferenced
1941 since the delete_insn above has deleted the BARRIER. */
1942 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1943 delete_insn (prev_label);
1948 /* Detect a jump to a jump. */
1950 nlabel = follow_jumps (JUMP_LABEL (insn));
1951 if (nlabel != JUMP_LABEL (insn)
1952 && redirect_jump (insn, nlabel))
1958 /* Look for if (foo) bar; else break; */
1959 /* The insns look like this:
1960 insn = condjump label1;
1961 ...range1 (some insns)...
1964 ...range2 (some insns)...
1965 jump somewhere unconditionally
1968 rtx label1 = next_label (insn);
1969 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1970 /* Don't do this optimization on the first round, so that
1971 jump-around-a-jump gets simplified before we ask here
1972 whether a jump is unconditional.
1974 Also don't do it when we are called after reload since
1975 it will confuse reorg. */
1977 && (reload_completed ? ! flag_delayed_branch : 1)
1978 /* Make sure INSN is something we can invert. */
1979 && condjump_p (insn)
1981 && JUMP_LABEL (insn) == label1
1982 && LABEL_NUSES (label1) == 1
1983 && GET_CODE (range1end) == JUMP_INSN
1984 && simplejump_p (range1end))
1986 rtx label2 = next_label (label1);
1987 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1988 if (range1end != range2end
1989 && JUMP_LABEL (range1end) == label2
1990 && GET_CODE (range2end) == JUMP_INSN
1991 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1992 /* Invert the jump condition, so we
1993 still execute the same insns in each case. */
1994 && invert_jump (insn, label1))
1996 rtx range1beg = next_active_insn (insn);
1997 rtx range2beg = next_active_insn (label1);
1998 rtx range1after, range2after;
1999 rtx range1before, range2before;
2002 /* Include in each range any notes before it, to be
2003 sure that we get the line number note if any, even
2004 if there are other notes here. */
2005 while (PREV_INSN (range1beg)
2006 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
2007 range1beg = PREV_INSN (range1beg);
2009 while (PREV_INSN (range2beg)
2010 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
2011 range2beg = PREV_INSN (range2beg);
2013 /* Don't move NOTEs for blocks or loops; shift them
2014 outside the ranges, where they'll stay put. */
2015 range1beg = squeeze_notes (range1beg, range1end);
2016 range2beg = squeeze_notes (range2beg, range2end);
2018 /* Get current surrounds of the 2 ranges. */
2019 range1before = PREV_INSN (range1beg);
2020 range2before = PREV_INSN (range2beg);
2021 range1after = NEXT_INSN (range1end);
2022 range2after = NEXT_INSN (range2end);
2024 /* Splice range2 where range1 was. */
2025 NEXT_INSN (range1before) = range2beg;
2026 PREV_INSN (range2beg) = range1before;
2027 NEXT_INSN (range2end) = range1after;
2028 PREV_INSN (range1after) = range2end;
2029 /* Splice range1 where range2 was. */
2030 NEXT_INSN (range2before) = range1beg;
2031 PREV_INSN (range1beg) = range2before;
2032 NEXT_INSN (range1end) = range2after;
2033 PREV_INSN (range2after) = range1end;
2035 /* Check for a loop end note between the end of
2036 range2, and the next code label. If there is one,
2037 then what we have really seen is
2038 if (foo) break; end_of_loop;
2039 and moved the break sequence outside the loop.
2040 We must move the LOOP_END note to where the
2041 loop really ends now, or we will confuse loop
2042 optimization. Stop if we find a LOOP_BEG note
2043 first, since we don't want to move the LOOP_END
2044 note in that case. */
2045 for (;range2after != label2; range2after = rangenext)
2047 rangenext = NEXT_INSN (range2after);
2048 if (GET_CODE (range2after) == NOTE)
2050 if (NOTE_LINE_NUMBER (range2after)
2051 == NOTE_INSN_LOOP_END)
2053 NEXT_INSN (PREV_INSN (range2after))
2055 PREV_INSN (rangenext)
2056 = PREV_INSN (range2after);
2057 PREV_INSN (range2after)
2058 = PREV_INSN (range1beg);
2059 NEXT_INSN (range2after) = range1beg;
2060 NEXT_INSN (PREV_INSN (range1beg))
2062 PREV_INSN (range1beg) = range2after;
2064 else if (NOTE_LINE_NUMBER (range2after)
2065 == NOTE_INSN_LOOP_BEG)
2075 /* Now that the jump has been tensioned,
2076 try cross jumping: check for identical code
2077 before the jump and before its target label. */
2079 /* First, cross jumping of conditional jumps: */
2081 if (cross_jump && condjump_p (insn))
2083 rtx newjpos, newlpos;
2084 rtx x = prev_real_insn (JUMP_LABEL (insn));
2086 /* A conditional jump may be crossjumped
2087 only if the place it jumps to follows
2088 an opposing jump that comes back here. */
2090 if (x != 0 && ! jump_back_p (x, insn))
2091 /* We have no opposing jump;
2092 cannot cross jump this insn. */
2096 /* TARGET is nonzero if it is ok to cross jump
2097 to code before TARGET. If so, see if matches. */
2099 find_cross_jump (insn, x, 2,
2100 &newjpos, &newlpos);
2104 do_cross_jump (insn, newjpos, newlpos);
2105 /* Make the old conditional jump
2106 into an unconditional one. */
2107 SET_SRC (PATTERN (insn))
2108 = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
2109 INSN_CODE (insn) = -1;
2110 emit_barrier_after (insn);
2111 /* Add to jump_chain unless this is a new label
2112 whose UID is too large. */
2113 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
2115 jump_chain[INSN_UID (insn)]
2116 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2117 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
2124 /* Cross jumping of unconditional jumps:
2125 a few differences. */
2127 if (cross_jump && simplejump_p (insn))
2129 rtx newjpos, newlpos;
2134 /* TARGET is nonzero if it is ok to cross jump
2135 to code before TARGET. If so, see if matches. */
2136 find_cross_jump (insn, JUMP_LABEL (insn), 1,
2137 &newjpos, &newlpos);
2139 /* If cannot cross jump to code before the label,
2140 see if we can cross jump to another jump to
2142 /* Try each other jump to this label. */
2143 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
2144 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
2145 target != 0 && newjpos == 0;
2146 target = jump_chain[INSN_UID (target)])
2148 && JUMP_LABEL (target) == JUMP_LABEL (insn)
2149 /* Ignore TARGET if it's deleted. */
2150 && ! INSN_DELETED_P (target))
2151 find_cross_jump (insn, target, 2,
2152 &newjpos, &newlpos);
2156 do_cross_jump (insn, newjpos, newlpos);
2162 /* This code was dead in the previous jump.c! */
2163 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2165 /* Return insns all "jump to the same place"
2166 so we can cross-jump between any two of them. */
2168 rtx newjpos, newlpos, target;
2172 /* If cannot cross jump to code before the label,
2173 see if we can cross jump to another jump to
2175 /* Try each other jump to this label. */
2176 for (target = jump_chain[0];
2177 target != 0 && newjpos == 0;
2178 target = jump_chain[INSN_UID (target)])
2180 && ! INSN_DELETED_P (target)
2181 && GET_CODE (PATTERN (target)) == RETURN)
2182 find_cross_jump (insn, target, 2,
2183 &newjpos, &newlpos);
2187 do_cross_jump (insn, newjpos, newlpos);
2198 /* Delete extraneous line number notes.
2199 Note that two consecutive notes for different lines are not really
2200 extraneous. There should be some indication where that line belonged,
2201 even if it became empty. */
2206 for (insn = f; insn; insn = NEXT_INSN (insn))
2207 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2209 /* Delete this note if it is identical to previous note. */
2211 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2212 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2225 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2226 in front of it. If the machine allows it at this point (we might be
2227 after reload for a leaf routine), it will improve optimization for it
2228 to be there. We do this both here and at the start of this pass since
2229 the RETURN might have been deleted by some of our optimizations. */
2230 insn = get_last_insn ();
2231 while (insn && GET_CODE (insn) == NOTE)
2232 insn = PREV_INSN (insn);
2234 if (insn && GET_CODE (insn) != BARRIER)
2236 emit_jump_insn (gen_return ());
2242 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2243 If so, delete it, and record that this function can drop off the end. */
2249 /* One label can follow the end-note: the return label. */
2250 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2251 /* Ordinary insns can follow it if returning a structure. */
2252 || GET_CODE (insn) == INSN
2253 /* If machine uses explicit RETURN insns, no epilogue,
2254 then one of them follows the note. */
2255 || (GET_CODE (insn) == JUMP_INSN
2256 && GET_CODE (PATTERN (insn)) == RETURN)
2257 /* A barrier can follow the return insn. */
2258 || GET_CODE (insn) == BARRIER
2259 /* Other kinds of notes can follow also. */
2260 || (GET_CODE (insn) == NOTE
2261 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2262 insn = PREV_INSN (insn);
2265 /* Report if control can fall through at the end of the function. */
2266 if (insn && GET_CODE (insn) == NOTE
2267 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2273 /* Show JUMP_CHAIN no longer valid. */
2277 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2278 jump. Assume that this unconditional jump is to the exit test code. If
2279 the code is sufficiently simple, make a copy of it before INSN,
2280 followed by a jump to the exit of the loop. Then delete the unconditional
2283 Return 1 if we made the change, else 0.
2285 This is only safe immediately after a regscan pass because it uses the
2286 values of regno_first_uid and regno_last_uid. */
2289 duplicate_loop_exit_test (loop_start)
2292 rtx insn, set, reg, p, link;
2295 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2297 int max_reg = max_reg_num ();
2300 /* Scan the exit code. We do not perform this optimization if any insn:
2304 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2305 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2306 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2309 Also, don't do this if the exit code is more than 20 insns. */
2311 for (insn = exitcode;
2313 && ! (GET_CODE (insn) == NOTE
2314 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2315 insn = NEXT_INSN (insn))
2317 switch (GET_CODE (insn))
2323 /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
2324 a jump immediately after the loop start that branches outside
2325 the loop but within an outer loop, near the exit test.
2326 If we copied this exit test and created a phony
2327 NOTE_INSN_LOOP_VTOP, this could make instructions immediately
2328 before the exit test look like these could be safely moved
2329 out of the loop even if they actually may be never executed.
2330 This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
2332 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2333 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2334 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2335 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2340 if (++num_insns > 20
2341 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2342 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2350 /* Unless INSN is zero, we can do the optimization. */
2356 /* See if any insn sets a register only used in the loop exit code and
2357 not a user variable. If so, replace it with a new register. */
2358 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2359 if (GET_CODE (insn) == INSN
2360 && (set = single_set (insn)) != 0
2361 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2362 || (GET_CODE (reg) == SUBREG
2363 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2364 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2365 && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
2367 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2368 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
2373 /* We can do the replacement. Allocate reg_map if this is the
2374 first replacement we found. */
2377 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2378 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2381 REG_LOOP_TEST_P (reg) = 1;
2383 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2387 /* Now copy each insn. */
2388 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2389 switch (GET_CODE (insn))
2392 copy = emit_barrier_before (loop_start);
2395 /* Only copy line-number notes. */
2396 if (NOTE_LINE_NUMBER (insn) >= 0)
2398 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2399 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2404 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2406 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2408 mark_jump_label (PATTERN (copy), copy, 0);
2410 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2412 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2413 if (REG_NOTE_KIND (link) != REG_LABEL)
2415 = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
2418 if (reg_map && REG_NOTES (copy))
2419 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2423 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2425 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2426 mark_jump_label (PATTERN (copy), copy, 0);
2427 if (REG_NOTES (insn))
2429 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2431 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2434 /* If this is a simple jump, add it to the jump chain. */
2436 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2437 && simplejump_p (copy))
2439 jump_chain[INSN_UID (copy)]
2440 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2441 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2449 /* Now clean up by emitting a jump to the end label and deleting the jump
2450 at the start of the loop. */
2451 if (! copy || GET_CODE (copy) != BARRIER)
2453 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2455 mark_jump_label (PATTERN (copy), copy, 0);
2456 if (INSN_UID (copy) < max_jump_chain
2457 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2459 jump_chain[INSN_UID (copy)]
2460 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2461 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2463 emit_barrier_before (loop_start);
2466 /* Mark the exit code as the virtual top of the converted loop. */
2467 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2469 delete_insn (next_nonnote_insn (loop_start));
2474 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2475 loop-end notes between START and END out before START. Assume that
2476 END is not such a note. START may be such a note. Returns the value
2477 of the new starting insn, which may be different if the original start
2481 squeeze_notes (start, end)
2487 for (insn = start; insn != end; insn = next)
2489 next = NEXT_INSN (insn);
2490 if (GET_CODE (insn) == NOTE
2491 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2492 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2493 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2494 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2495 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2496 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2502 rtx prev = PREV_INSN (insn);
2503 PREV_INSN (insn) = PREV_INSN (start);
2504 NEXT_INSN (insn) = start;
2505 NEXT_INSN (PREV_INSN (insn)) = insn;
2506 PREV_INSN (NEXT_INSN (insn)) = insn;
2507 NEXT_INSN (prev) = next;
2508 PREV_INSN (next) = prev;
2516 /* Compare the instructions before insn E1 with those before E2
2517 to find an opportunity for cross jumping.
2518 (This means detecting identical sequences of insns followed by
2519 jumps to the same place, or followed by a label and a jump
2520 to that label, and replacing one with a jump to the other.)
2522 Assume E1 is a jump that jumps to label E2
2523 (that is not always true but it might as well be).
2524 Find the longest possible equivalent sequences
2525 and store the first insns of those sequences into *F1 and *F2.
2526 Store zero there if no equivalent preceding instructions are found.
2528 We give up if we find a label in stream 1.
2529 Actually we could transfer that label into stream 2. */
2532 find_cross_jump (e1, e2, minimum, f1, f2)
2537 register rtx i1 = e1, i2 = e2;
2538 register rtx p1, p2;
2541 rtx last1 = 0, last2 = 0;
2542 rtx afterlast1 = 0, afterlast2 = 0;
2549 i1 = prev_nonnote_insn (i1);
2551 i2 = PREV_INSN (i2);
2552 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2553 i2 = PREV_INSN (i2);
2558 /* Don't allow the range of insns preceding E1 or E2
2559 to include the other (E2 or E1). */
2560 if (i2 == e1 || i1 == e2)
2563 /* If we will get to this code by jumping, those jumps will be
2564 tensioned to go directly to the new label (before I2),
2565 so this cross-jumping won't cost extra. So reduce the minimum. */
2566 if (GET_CODE (i1) == CODE_LABEL)
2572 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2578 /* If this is a CALL_INSN, compare register usage information.
2579 If we don't check this on stack register machines, the two
2580 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2581 numbers of stack registers in the same basic block.
2582 If we don't check this on machines with delay slots, a delay slot may
2583 be filled that clobbers a parameter expected by the subroutine.
2585 ??? We take the simple route for now and assume that if they're
2586 equal, they were constructed identically. */
2588 if (GET_CODE (i1) == CALL_INSN
2589 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2590 CALL_INSN_FUNCTION_USAGE (i2)))
2594 /* If cross_jump_death_matters is not 0, the insn's mode
2595 indicates whether or not the insn contains any stack-like
2598 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2600 /* If register stack conversion has already been done, then
2601 death notes must also be compared before it is certain that
2602 the two instruction streams match. */
2605 HARD_REG_SET i1_regset, i2_regset;
2607 CLEAR_HARD_REG_SET (i1_regset);
2608 CLEAR_HARD_REG_SET (i2_regset);
2610 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2611 if (REG_NOTE_KIND (note) == REG_DEAD
2612 && STACK_REG_P (XEXP (note, 0)))
2613 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2615 for (note = REG_NOTES (i2); 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 (i2_regset, REGNO (XEXP (note, 0)));
2620 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2629 /* Don't allow old-style asm or volatile extended asms to be accepted
2630 for cross jumping purposes. It is conceptually correct to allow
2631 them, since cross-jumping preserves the dynamic instruction order
2632 even though it is changing the static instruction order. However,
2633 if an asm is being used to emit an assembler pseudo-op, such as
2634 the MIPS `.set reorder' pseudo-op, then the static instruction order
2635 matters and it must be preserved. */
2636 if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
2637 || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
2638 || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
2641 if (lose || GET_CODE (p1) != GET_CODE (p2)
2642 || ! rtx_renumbered_equal_p (p1, p2))
2644 /* The following code helps take care of G++ cleanups. */
2648 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2649 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2650 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2651 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2652 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2653 /* If the equivalences are not to a constant, they may
2654 reference pseudos that no longer exist, so we can't
2656 && CONSTANT_P (XEXP (equiv1, 0))
2657 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2659 rtx s1 = single_set (i1);
2660 rtx s2 = single_set (i2);
2661 if (s1 != 0 && s2 != 0
2662 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2664 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2665 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2666 if (! rtx_renumbered_equal_p (p1, p2))
2668 else if (apply_change_group ())
2673 /* Insns fail to match; cross jumping is limited to the following
2677 /* Don't allow the insn after a compare to be shared by
2678 cross-jumping unless the compare is also shared.
2679 Here, if either of these non-matching insns is a compare,
2680 exclude the following insn from possible cross-jumping. */
2681 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2682 last1 = afterlast1, last2 = afterlast2, ++minimum;
2685 /* If cross-jumping here will feed a jump-around-jump
2686 optimization, this jump won't cost extra, so reduce
2688 if (GET_CODE (i1) == JUMP_INSN
2690 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2696 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2698 /* Ok, this insn is potentially includable in a cross-jump here. */
2699 afterlast1 = last1, afterlast2 = last2;
2700 last1 = i1, last2 = i2, --minimum;
2704 if (minimum <= 0 && last1 != 0 && last1 != e1)
2705 *f1 = last1, *f2 = last2;
2709 do_cross_jump (insn, newjpos, newlpos)
2710 rtx insn, newjpos, newlpos;
2712 /* Find an existing label at this point
2713 or make a new one if there is none. */
2714 register rtx label = get_label_before (newlpos);
2716 /* Make the same jump insn jump to the new point. */
2717 if (GET_CODE (PATTERN (insn)) == RETURN)
2719 /* Remove from jump chain of returns. */
2720 delete_from_jump_chain (insn);
2721 /* Change the insn. */
2722 PATTERN (insn) = gen_jump (label);
2723 INSN_CODE (insn) = -1;
2724 JUMP_LABEL (insn) = label;
2725 LABEL_NUSES (label)++;
2726 /* Add to new the jump chain. */
2727 if (INSN_UID (label) < max_jump_chain
2728 && INSN_UID (insn) < max_jump_chain)
2730 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2731 jump_chain[INSN_UID (label)] = insn;
2735 redirect_jump (insn, label);
2737 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2738 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2739 the NEWJPOS stream. */
2741 while (newjpos != insn)
2745 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2746 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2747 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2748 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2749 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2750 remove_note (newlpos, lnote);
2752 delete_insn (newjpos);
2753 newjpos = next_real_insn (newjpos);
2754 newlpos = next_real_insn (newlpos);
2758 /* Return the label before INSN, or put a new label there. */
2761 get_label_before (insn)
2766 /* Find an existing label at this point
2767 or make a new one if there is none. */
2768 label = prev_nonnote_insn (insn);
2770 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2772 rtx prev = PREV_INSN (insn);
2774 label = gen_label_rtx ();
2775 emit_label_after (label, prev);
2776 LABEL_NUSES (label) = 0;
2781 /* Return the label after INSN, or put a new label there. */
2784 get_label_after (insn)
2789 /* Find an existing label at this point
2790 or make a new one if there is none. */
2791 label = next_nonnote_insn (insn);
2793 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2795 label = gen_label_rtx ();
2796 emit_label_after (label, insn);
2797 LABEL_NUSES (label) = 0;
2802 /* Return 1 if INSN is a jump that jumps to right after TARGET
2803 only on the condition that TARGET itself would drop through.
2804 Assumes that TARGET is a conditional jump. */
2807 jump_back_p (insn, target)
2811 enum rtx_code codei, codet;
2813 if (simplejump_p (insn) || ! condjump_p (insn)
2814 || simplejump_p (target)
2815 || target != prev_real_insn (JUMP_LABEL (insn)))
2818 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2819 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2821 codei = GET_CODE (cinsn);
2822 codet = GET_CODE (ctarget);
2824 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2826 if (! can_reverse_comparison_p (cinsn, insn))
2828 codei = reverse_condition (codei);
2831 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2833 if (! can_reverse_comparison_p (ctarget, target))
2835 codet = reverse_condition (codet);
2838 return (codei == codet
2839 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2840 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2843 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2844 return non-zero if it is safe to reverse this comparison. It is if our
2845 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2846 this is known to be an integer comparison. */
2849 can_reverse_comparison_p (comparison, insn)
2855 /* If this is not actually a comparison, we can't reverse it. */
2856 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2859 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2860 /* If this is an NE comparison, it is safe to reverse it to an EQ
2861 comparison and vice versa, even for floating point. If no operands
2862 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2863 always false and NE is always true, so the reversal is also valid. */
2865 || GET_CODE (comparison) == NE
2866 || GET_CODE (comparison) == EQ)
2869 arg0 = XEXP (comparison, 0);
2871 /* Make sure ARG0 is one of the actual objects being compared. If we
2872 can't do this, we can't be sure the comparison can be reversed.
2874 Handle cc0 and a MODE_CC register. */
2875 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2881 rtx prev = prev_nonnote_insn (insn);
2882 rtx set = single_set (prev);
2884 if (set == 0 || SET_DEST (set) != arg0)
2887 arg0 = SET_SRC (set);
2889 if (GET_CODE (arg0) == COMPARE)
2890 arg0 = XEXP (arg0, 0);
2893 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2894 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2895 return (GET_CODE (arg0) == CONST_INT
2896 || (GET_MODE (arg0) != VOIDmode
2897 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2898 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2901 /* Given an rtx-code for a comparison, return the code
2902 for the negated comparison.
2903 WATCH OUT! reverse_condition is not safe to use on a jump
2904 that might be acting on the results of an IEEE floating point comparison,
2905 because of the special treatment of non-signaling nans in comparisons.
2906 Use can_reverse_comparison_p to be sure. */
2909 reverse_condition (code)
2950 /* Similar, but return the code when two operands of a comparison are swapped.
2951 This IS safe for IEEE floating-point. */
2954 swap_condition (code)
2993 /* Given a comparison CODE, return the corresponding unsigned comparison.
2994 If CODE is an equality comparison or already an unsigned comparison,
2995 CODE is returned. */
2998 unsigned_condition (code)
3028 /* Similarly, return the signed version of a comparison. */
3031 signed_condition (code)
3061 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
3062 truth of CODE1 implies the truth of CODE2. */
3065 comparison_dominates_p (code1, code2)
3066 enum rtx_code code1, code2;
3074 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
3079 if (code2 == LE || code2 == NE)
3084 if (code2 == GE || code2 == NE)
3089 if (code2 == LEU || code2 == NE)
3094 if (code2 == GEU || code2 == NE)
3105 /* Return 1 if INSN is an unconditional jump and nothing else. */
3111 return (GET_CODE (insn) == JUMP_INSN
3112 && GET_CODE (PATTERN (insn)) == SET
3113 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
3114 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
3117 /* Return nonzero if INSN is a (possibly) conditional jump
3118 and nothing more. */
3124 register rtx x = PATTERN (insn);
3125 if (GET_CODE (x) != SET)
3127 if (GET_CODE (SET_DEST (x)) != PC)
3129 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3131 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3133 if (XEXP (SET_SRC (x), 2) == pc_rtx
3134 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3135 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3137 if (XEXP (SET_SRC (x), 1) == pc_rtx
3138 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3139 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3144 /* Return nonzero if INSN is a (possibly) conditional jump
3145 and nothing more. */
3148 condjump_in_parallel_p (insn)
3151 register rtx x = PATTERN (insn);
3153 if (GET_CODE (x) != PARALLEL)
3156 x = XVECEXP (x, 0, 0);
3158 if (GET_CODE (x) != SET)
3160 if (GET_CODE (SET_DEST (x)) != PC)
3162 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
3164 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
3166 if (XEXP (SET_SRC (x), 2) == pc_rtx
3167 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
3168 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
3170 if (XEXP (SET_SRC (x), 1) == pc_rtx
3171 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
3172 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
3177 /* Return 1 if X is an RTX that does nothing but set the condition codes
3178 and CLOBBER or USE registers.
3179 Return -1 if X does explicitly set the condition codes,
3180 but also does other things. */
3187 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3189 if (GET_CODE (x) == PARALLEL)
3193 int other_things = 0;
3194 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3196 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3197 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3199 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3202 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3210 /* Follow any unconditional jump at LABEL;
3211 return the ultimate label reached by any such chain of jumps.
3212 If LABEL is not followed by a jump, return LABEL.
3213 If the chain loops or we can't find end, return LABEL,
3214 since that tells caller to avoid changing the insn.
3216 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3217 a USE or CLOBBER. */
3220 follow_jumps (label)
3225 register rtx value = label;
3230 && (insn = next_active_insn (value)) != 0
3231 && GET_CODE (insn) == JUMP_INSN
3232 && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
3233 || GET_CODE (PATTERN (insn)) == RETURN)
3234 && (next = NEXT_INSN (insn))
3235 && GET_CODE (next) == BARRIER);
3238 /* Don't chain through the insn that jumps into a loop
3239 from outside the loop,
3240 since that would create multiple loop entry jumps
3241 and prevent loop optimization. */
3243 if (!reload_completed)
3244 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3245 if (GET_CODE (tem) == NOTE
3246 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
3247 /* ??? Optional. Disables some optimizations, but makes
3248 gcov output more accurate with -O. */
3249 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
3252 /* If we have found a cycle, make the insn jump to itself. */
3253 if (JUMP_LABEL (insn) == label)
3256 tem = next_active_insn (JUMP_LABEL (insn));
3257 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3258 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3261 value = JUMP_LABEL (insn);
3268 /* Assuming that field IDX of X is a vector of label_refs,
3269 replace each of them by the ultimate label reached by it.
3270 Return nonzero if a change is made.
3271 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3274 tension_vector_labels (x, idx)
3280 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3282 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3283 register rtx nlabel = follow_jumps (olabel);
3284 if (nlabel && nlabel != olabel)
3286 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3287 ++LABEL_NUSES (nlabel);
3288 if (--LABEL_NUSES (olabel) == 0)
3289 delete_insn (olabel);
3296 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3297 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3298 in INSN, then store one of them in JUMP_LABEL (INSN).
3299 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3300 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3301 Also, when there are consecutive labels, canonicalize on the last of them.
3303 Note that two labels separated by a loop-beginning note
3304 must be kept distinct if we have not yet done loop-optimization,
3305 because the gap between them is where loop-optimize
3306 will want to move invariant code to. CROSS_JUMP tells us
3307 that loop-optimization is done with.
3309 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3310 two labels distinct if they are separated by only USE or CLOBBER insns. */
3313 mark_jump_label (x, insn, cross_jump)
3318 register RTX_CODE code = GET_CODE (x);
3336 /* If this is a constant-pool reference, see if it is a label. */
3337 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3338 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3339 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3344 rtx label = XEXP (x, 0);
3349 if (GET_CODE (label) != CODE_LABEL)
3352 /* Ignore references to labels of containing functions. */
3353 if (LABEL_REF_NONLOCAL_P (x))
3356 /* If there are other labels following this one,
3357 replace it with the last of the consecutive labels. */
3358 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3360 if (GET_CODE (next) == CODE_LABEL)
3362 else if (cross_jump && GET_CODE (next) == INSN
3363 && (GET_CODE (PATTERN (next)) == USE
3364 || GET_CODE (PATTERN (next)) == CLOBBER))
3366 else if (GET_CODE (next) != NOTE)
3368 else if (! cross_jump
3369 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3370 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END
3371 /* ??? Optional. Disables some optimizations, but
3372 makes gcov output more accurate with -O. */
3373 || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0)))
3377 XEXP (x, 0) = label;
3378 if (! insn || ! INSN_DELETED_P (insn))
3379 ++LABEL_NUSES (label);
3383 if (GET_CODE (insn) == JUMP_INSN)
3384 JUMP_LABEL (insn) = label;
3386 /* If we've changed OLABEL and we had a REG_LABEL note
3387 for it, update it as well. */
3388 else if (label != olabel
3389 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3390 XEXP (note, 0) = label;
3392 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3394 else if (! find_reg_note (insn, REG_LABEL, label))
3396 /* This code used to ignore labels which refered to dispatch
3397 tables to avoid flow.c generating worse code.
3399 However, in the presense of global optimizations like
3400 gcse which call find_basic_blocks without calling
3401 life_analysis, not recording such labels will lead
3402 to compiler aborts because of inconsistencies in the
3403 flow graph. So we go ahead and record the label.
3405 It may also be the case that the optimization argument
3406 is no longer valid because of the more accurate cfg
3407 we build in find_basic_blocks -- it no longer pessimizes
3408 code when it finds a REG_LABEL note. */
3409 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label,
3416 /* Do walk the labels in a vector, but not the first operand of an
3417 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3420 if (! INSN_DELETED_P (insn))
3422 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3424 for (i = 0; i < XVECLEN (x, eltnum); i++)
3425 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3433 fmt = GET_RTX_FORMAT (code);
3434 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3437 mark_jump_label (XEXP (x, i), insn, cross_jump);
3438 else if (fmt[i] == 'E')
3441 for (j = 0; j < XVECLEN (x, i); j++)
3442 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3447 /* If all INSN does is set the pc, delete it,
3448 and delete the insn that set the condition codes for it
3449 if that's what the previous thing was. */
3455 register rtx set = single_set (insn);
3457 if (set && GET_CODE (SET_DEST (set)) == PC)
3458 delete_computation (insn);
3461 /* Delete INSN and recursively delete insns that compute values used only
3462 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3463 If we are running before flow.c, we need do nothing since flow.c will
3464 delete dead code. We also can't know if the registers being used are
3465 dead or not at this point.
3467 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3468 nothing other than set a register that dies in this insn, we can delete
3471 On machines with CC0, if CC0 is used in this insn, we may be able to
3472 delete the insn that set it. */
3475 delete_computation (insn)
3481 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3483 rtx prev = prev_nonnote_insn (insn);
3484 /* We assume that at this stage
3485 CC's are always set explicitly
3486 and always immediately before the jump that
3487 will use them. So if the previous insn
3488 exists to set the CC's, delete it
3489 (unless it performs auto-increments, etc.). */
3490 if (prev && GET_CODE (prev) == INSN
3491 && sets_cc0_p (PATTERN (prev)))
3493 if (sets_cc0_p (PATTERN (prev)) > 0
3494 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3495 delete_computation (prev);
3497 /* Otherwise, show that cc0 won't be used. */
3498 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
3499 cc0_rtx, REG_NOTES (prev));
3504 for (note = REG_NOTES (insn); note; note = next)
3508 next = XEXP (note, 1);
3510 if (REG_NOTE_KIND (note) != REG_DEAD
3511 /* Verify that the REG_NOTE is legitimate. */
3512 || GET_CODE (XEXP (note, 0)) != REG)
3515 for (our_prev = prev_nonnote_insn (insn);
3516 our_prev && GET_CODE (our_prev) == INSN;
3517 our_prev = prev_nonnote_insn (our_prev))
3519 /* If we reach a SEQUENCE, it is too complex to try to
3520 do anything with it, so give up. */
3521 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3524 if (GET_CODE (PATTERN (our_prev)) == USE
3525 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3526 /* reorg creates USEs that look like this. We leave them
3527 alone because reorg needs them for its own purposes. */
3530 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3532 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3535 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3537 /* If we find a SET of something else, we can't
3542 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3544 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3546 if (GET_CODE (part) == SET
3547 && SET_DEST (part) != XEXP (note, 0))
3551 if (i == XVECLEN (PATTERN (our_prev), 0))
3552 delete_computation (our_prev);
3554 else if (GET_CODE (PATTERN (our_prev)) == SET
3555 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3556 delete_computation (our_prev);
3561 /* If OUR_PREV references the register that dies here, it is an
3562 additional use. Hence any prior SET isn't dead. However, this
3563 insn becomes the new place for the REG_DEAD note. */
3564 if (reg_overlap_mentioned_p (XEXP (note, 0),
3565 PATTERN (our_prev)))
3567 XEXP (note, 1) = REG_NOTES (our_prev);
3568 REG_NOTES (our_prev) = note;
3577 /* Delete insn INSN from the chain of insns and update label ref counts.
3578 May delete some following insns as a consequence; may even delete
3579 a label elsewhere and insns that follow it.
3581 Returns the first insn after INSN that was not deleted. */
3587 register rtx next = NEXT_INSN (insn);
3588 register rtx prev = PREV_INSN (insn);
3589 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3590 register int dont_really_delete = 0;
3592 while (next && INSN_DELETED_P (next))
3593 next = NEXT_INSN (next);
3595 /* This insn is already deleted => return first following nondeleted. */
3596 if (INSN_DELETED_P (insn))
3599 /* Don't delete user-declared labels. Convert them to special NOTEs
3601 if (was_code_label && LABEL_NAME (insn) != 0
3602 && optimize && ! dont_really_delete)
3604 PUT_CODE (insn, NOTE);
3605 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3606 NOTE_SOURCE_FILE (insn) = 0;
3607 dont_really_delete = 1;
3610 /* Mark this insn as deleted. */
3611 INSN_DELETED_P (insn) = 1;
3613 /* If this is an unconditional jump, delete it from the jump chain. */
3614 if (simplejump_p (insn))
3615 delete_from_jump_chain (insn);
3617 /* If instruction is followed by a barrier,
3618 delete the barrier too. */
3620 if (next != 0 && GET_CODE (next) == BARRIER)
3622 INSN_DELETED_P (next) = 1;
3623 next = NEXT_INSN (next);
3626 /* Patch out INSN (and the barrier if any) */
3628 if (optimize && ! dont_really_delete)
3632 NEXT_INSN (prev) = next;
3633 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3634 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3635 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3640 PREV_INSN (next) = prev;
3641 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3642 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3645 if (prev && NEXT_INSN (prev) == 0)
3646 set_last_insn (prev);
3649 /* If deleting a jump, decrement the count of the label,
3650 and delete the label if it is now unused. */
3652 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3653 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3655 /* This can delete NEXT or PREV,
3656 either directly if NEXT is JUMP_LABEL (INSN),
3657 or indirectly through more levels of jumps. */
3658 delete_insn (JUMP_LABEL (insn));
3659 /* I feel a little doubtful about this loop,
3660 but I see no clean and sure alternative way
3661 to find the first insn after INSN that is not now deleted.
3662 I hope this works. */
3663 while (next && INSN_DELETED_P (next))
3664 next = NEXT_INSN (next);
3668 /* Likewise if we're deleting a dispatch table. */
3670 if (GET_CODE (insn) == JUMP_INSN
3671 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3672 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3674 rtx pat = PATTERN (insn);
3675 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3676 int len = XVECLEN (pat, diff_vec_p);
3678 for (i = 0; i < len; i++)
3679 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3680 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3681 while (next && INSN_DELETED_P (next))
3682 next = NEXT_INSN (next);
3686 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3687 prev = PREV_INSN (prev);
3689 /* If INSN was a label and a dispatch table follows it,
3690 delete the dispatch table. The tablejump must have gone already.
3691 It isn't useful to fall through into a table. */
3694 && NEXT_INSN (insn) != 0
3695 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3696 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3697 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3698 next = delete_insn (NEXT_INSN (insn));
3700 /* If INSN was a label, delete insns following it if now unreachable. */
3702 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3704 register RTX_CODE code;
3706 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3707 || code == NOTE || code == BARRIER
3708 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3711 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3712 next = NEXT_INSN (next);
3713 /* Keep going past other deleted labels to delete what follows. */
3714 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3715 next = NEXT_INSN (next);
3717 /* Note: if this deletes a jump, it can cause more
3718 deletion of unreachable code, after a different label.
3719 As long as the value from this recursive call is correct,
3720 this invocation functions correctly. */
3721 next = delete_insn (next);
3728 /* Advance from INSN till reaching something not deleted
3729 then return that. May return INSN itself. */
3732 next_nondeleted_insn (insn)
3735 while (INSN_DELETED_P (insn))
3736 insn = NEXT_INSN (insn);
3740 /* Delete a range of insns from FROM to TO, inclusive.
3741 This is for the sake of peephole optimization, so assume
3742 that whatever these insns do will still be done by a new
3743 peephole insn that will replace them. */
3746 delete_for_peephole (from, to)
3747 register rtx from, to;
3749 register rtx insn = from;
3753 register rtx next = NEXT_INSN (insn);
3754 register rtx prev = PREV_INSN (insn);
3756 if (GET_CODE (insn) != NOTE)
3758 INSN_DELETED_P (insn) = 1;
3760 /* Patch this insn out of the chain. */
3761 /* We don't do this all at once, because we
3762 must preserve all NOTEs. */
3764 NEXT_INSN (prev) = next;
3767 PREV_INSN (next) = prev;
3775 /* Note that if TO is an unconditional jump
3776 we *do not* delete the BARRIER that follows,
3777 since the peephole that replaces this sequence
3778 is also an unconditional jump in that case. */
3781 /* Invert the condition of the jump JUMP, and make it jump
3782 to label NLABEL instead of where it jumps now. */
3785 invert_jump (jump, nlabel)
3788 /* We have to either invert the condition and change the label or
3789 do neither. Either operation could fail. We first try to invert
3790 the jump. If that succeeds, we try changing the label. If that fails,
3791 we invert the jump back to what it was. */
3793 if (! invert_exp (PATTERN (jump), jump))
3796 if (redirect_jump (jump, nlabel))
3798 if (flag_branch_probabilities)
3800 rtx note = find_reg_note (jump, REG_BR_PROB, 0);
3802 /* An inverted jump means that a probability taken becomes a
3803 probability not taken. Subtract the branch probability from the
3804 probability base to convert it back to a taken probability.
3805 (We don't flip the probability on a branch that's never taken. */
3806 if (note && XINT (XEXP (note, 0), 0) >= 0)
3807 XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0);
3813 if (! invert_exp (PATTERN (jump), jump))
3814 /* This should just be putting it back the way it was. */
3820 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3822 Return 1 if we can do so, 0 if we cannot find a way to do so that
3823 matches a pattern. */
3826 invert_exp (x, insn)
3830 register RTX_CODE code;
3834 code = GET_CODE (x);
3836 if (code == IF_THEN_ELSE)
3838 register rtx comp = XEXP (x, 0);
3841 /* We can do this in two ways: The preferable way, which can only
3842 be done if this is not an integer comparison, is to reverse
3843 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3844 of the IF_THEN_ELSE. If we can't do either, fail. */
3846 if (can_reverse_comparison_p (comp, insn)
3847 && validate_change (insn, &XEXP (x, 0),
3848 gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)),
3849 GET_MODE (comp), XEXP (comp, 0),
3850 XEXP (comp, 1)), 0))
3854 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3855 validate_change (insn, &XEXP (x, 2), tem, 1);
3856 return apply_change_group ();
3859 fmt = GET_RTX_FORMAT (code);
3860 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3863 if (! invert_exp (XEXP (x, i), insn))
3868 for (j = 0; j < XVECLEN (x, i); j++)
3869 if (!invert_exp (XVECEXP (x, i, j), insn))
3877 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3878 If the old jump target label is unused as a result,
3879 it and the code following it may be deleted.
3881 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3884 The return value will be 1 if the change was made, 0 if it wasn't (this
3885 can only occur for NLABEL == 0). */
3888 redirect_jump (jump, nlabel)
3891 register rtx olabel = JUMP_LABEL (jump);
3893 if (nlabel == olabel)
3896 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3899 /* If this is an unconditional branch, delete it from the jump_chain of
3900 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3901 have UID's in range and JUMP_CHAIN is valid). */
3902 if (jump_chain && (simplejump_p (jump)
3903 || GET_CODE (PATTERN (jump)) == RETURN))
3905 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3907 delete_from_jump_chain (jump);
3908 if (label_index < max_jump_chain
3909 && INSN_UID (jump) < max_jump_chain)
3911 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3912 jump_chain[label_index] = jump;
3916 JUMP_LABEL (jump) = nlabel;
3918 ++LABEL_NUSES (nlabel);
3920 if (olabel && --LABEL_NUSES (olabel) == 0)
3921 delete_insn (olabel);
3926 /* Delete the instruction JUMP from any jump chain it might be on. */
3929 delete_from_jump_chain (jump)
3933 rtx olabel = JUMP_LABEL (jump);
3935 /* Handle unconditional jumps. */
3936 if (jump_chain && olabel != 0
3937 && INSN_UID (olabel) < max_jump_chain
3938 && simplejump_p (jump))
3939 index = INSN_UID (olabel);
3940 /* Handle return insns. */
3941 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3945 if (jump_chain[index] == jump)
3946 jump_chain[index] = jump_chain[INSN_UID (jump)];
3951 for (insn = jump_chain[index];
3953 insn = jump_chain[INSN_UID (insn)])
3954 if (jump_chain[INSN_UID (insn)] == jump)
3956 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3962 /* If NLABEL is nonzero, throughout the rtx at LOC,
3963 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3964 zero, alter (RETURN) to (LABEL_REF NLABEL).
3966 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3967 validity with validate_change. Convert (set (pc) (label_ref olabel))
3970 Return 0 if we found a change we would like to make but it is invalid.
3971 Otherwise, return 1. */
3974 redirect_exp (loc, olabel, nlabel, insn)
3979 register rtx x = *loc;
3980 register RTX_CODE code = GET_CODE (x);
3984 if (code == LABEL_REF)
3986 if (XEXP (x, 0) == olabel)
3989 XEXP (x, 0) = nlabel;
3991 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
3995 else if (code == RETURN && olabel == 0)
3997 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
3998 if (loc == &PATTERN (insn))
3999 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
4000 return validate_change (insn, loc, x, 0);
4003 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
4004 && GET_CODE (SET_SRC (x)) == LABEL_REF
4005 && XEXP (SET_SRC (x), 0) == olabel)
4006 return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0);
4008 fmt = GET_RTX_FORMAT (code);
4009 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4012 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
4017 for (j = 0; j < XVECLEN (x, i); j++)
4018 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
4026 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
4028 If the old jump target label (before the dispatch table) becomes unused,
4029 it and the dispatch table may be deleted. In that case, find the insn
4030 before the jump references that label and delete it and logical successors
4034 redirect_tablejump (jump, nlabel)
4037 register rtx olabel = JUMP_LABEL (jump);
4039 /* Add this jump to the jump_chain of NLABEL. */
4040 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
4041 && INSN_UID (jump) < max_jump_chain)
4043 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
4044 jump_chain[INSN_UID (nlabel)] = jump;
4047 PATTERN (jump) = gen_jump (nlabel);
4048 JUMP_LABEL (jump) = nlabel;
4049 ++LABEL_NUSES (nlabel);
4050 INSN_CODE (jump) = -1;
4052 if (--LABEL_NUSES (olabel) == 0)
4054 delete_labelref_insn (jump, olabel, 0);
4055 delete_insn (olabel);
4059 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
4060 If we found one, delete it and then delete this insn if DELETE_THIS is
4061 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
4064 delete_labelref_insn (insn, label, delete_this)
4071 if (GET_CODE (insn) != NOTE
4072 && reg_mentioned_p (label, PATTERN (insn)))
4083 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
4084 if (delete_labelref_insn (XEXP (link, 0), label, 1))
4098 /* Like rtx_equal_p except that it considers two REGs as equal
4099 if they renumber to the same value and considers two commutative
4100 operations to be the same if the order of the operands has been
4104 rtx_renumbered_equal_p (x, y)
4108 register RTX_CODE code = GET_CODE (x);
4114 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
4115 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
4116 && GET_CODE (SUBREG_REG (y)) == REG)))
4118 int reg_x = -1, reg_y = -1;
4119 int word_x = 0, word_y = 0;
4121 if (GET_MODE (x) != GET_MODE (y))
4124 /* If we haven't done any renumbering, don't
4125 make any assumptions. */
4126 if (reg_renumber == 0)
4127 return rtx_equal_p (x, y);
4131 reg_x = REGNO (SUBREG_REG (x));
4132 word_x = SUBREG_WORD (x);
4134 if (reg_renumber[reg_x] >= 0)
4136 reg_x = reg_renumber[reg_x] + word_x;
4144 if (reg_renumber[reg_x] >= 0)
4145 reg_x = reg_renumber[reg_x];
4148 if (GET_CODE (y) == SUBREG)
4150 reg_y = REGNO (SUBREG_REG (y));
4151 word_y = SUBREG_WORD (y);
4153 if (reg_renumber[reg_y] >= 0)
4155 reg_y = reg_renumber[reg_y];
4163 if (reg_renumber[reg_y] >= 0)
4164 reg_y = reg_renumber[reg_y];
4167 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
4170 /* Now we have disposed of all the cases
4171 in which different rtx codes can match. */
4172 if (code != GET_CODE (y))
4184 return INTVAL (x) == INTVAL (y);
4187 /* We can't assume nonlocal labels have their following insns yet. */
4188 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
4189 return XEXP (x, 0) == XEXP (y, 0);
4191 /* Two label-refs are equivalent if they point at labels
4192 in the same position in the instruction stream. */
4193 return (next_real_insn (XEXP (x, 0))
4194 == next_real_insn (XEXP (y, 0)));
4197 return XSTR (x, 0) == XSTR (y, 0);
4203 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
4205 if (GET_MODE (x) != GET_MODE (y))
4208 /* For commutative operations, the RTX match if the operand match in any
4209 order. Also handle the simple binary and unary cases without a loop. */
4210 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4211 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4212 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
4213 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
4214 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
4215 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4216 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4217 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4218 else if (GET_RTX_CLASS (code) == '1')
4219 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4221 /* Compare the elements. If any pair of corresponding elements
4222 fail to match, return 0 for the whole things. */
4224 fmt = GET_RTX_FORMAT (code);
4225 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4231 if (XWINT (x, i) != XWINT (y, i))
4236 if (XINT (x, i) != XINT (y, i))
4241 if (strcmp (XSTR (x, i), XSTR (y, i)))
4246 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4251 if (XEXP (x, i) != XEXP (y, i))
4258 if (XVECLEN (x, i) != XVECLEN (y, i))
4260 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4261 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4272 /* If X is a hard register or equivalent to one or a subregister of one,
4273 return the hard register number. If X is a pseudo register that was not
4274 assigned a hard register, return the pseudo register number. Otherwise,
4275 return -1. Any rtx is valid for X. */
4281 if (GET_CODE (x) == REG)
4283 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4284 return reg_renumber[REGNO (x)];
4287 if (GET_CODE (x) == SUBREG)
4289 int base = true_regnum (SUBREG_REG (x));
4290 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4291 return SUBREG_WORD (x) + base;
4296 /* Optimize code of the form:
4298 for (x = a[i]; x; ...)
4300 for (x = a[i]; x; ...)
4304 Loop optimize will change the above code into
4308 { ...; if (! (x = ...)) break; }
4311 { ...; if (! (x = ...)) break; }
4314 In general, if the first test fails, the program can branch
4315 directly to `foo' and skip the second try which is doomed to fail.
4316 We run this after loop optimization and before flow analysis. */
4318 /* When comparing the insn patterns, we track the fact that different
4319 pseudo-register numbers may have been used in each computation.
4320 The following array stores an equivalence -- same_regs[I] == J means
4321 that pseudo register I was used in the first set of tests in a context
4322 where J was used in the second set. We also count the number of such
4323 pending equivalences. If nonzero, the expressions really aren't the
4326 static int *same_regs;
4328 static int num_same_regs;
4330 /* Track any registers modified between the target of the first jump and
4331 the second jump. They never compare equal. */
4333 static char *modified_regs;
4335 /* Record if memory was modified. */
4337 static int modified_mem;
4339 /* Called via note_stores on each insn between the target of the first
4340 branch and the second branch. It marks any changed registers. */
4343 mark_modified_reg (dest, x)
4345 rtx x ATTRIBUTE_UNUSED;
4349 if (GET_CODE (dest) == SUBREG)
4350 dest = SUBREG_REG (dest);
4352 if (GET_CODE (dest) == MEM)
4355 if (GET_CODE (dest) != REG)
4358 regno = REGNO (dest);
4359 if (regno >= FIRST_PSEUDO_REGISTER)
4360 modified_regs[regno] = 1;
4362 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4363 modified_regs[regno + i] = 1;
4366 /* F is the first insn in the chain of insns. */
4369 thread_jumps (f, max_reg, flag_before_loop)
4372 int flag_before_loop;
4374 /* Basic algorithm is to find a conditional branch,
4375 the label it may branch to, and the branch after
4376 that label. If the two branches test the same condition,
4377 walk back from both branch paths until the insn patterns
4378 differ, or code labels are hit. If we make it back to
4379 the target of the first branch, then we know that the first branch
4380 will either always succeed or always fail depending on the relative
4381 senses of the two branches. So adjust the first branch accordingly
4384 rtx label, b1, b2, t1, t2;
4385 enum rtx_code code1, code2;
4386 rtx b1op0, b1op1, b2op0, b2op1;
4391 /* Allocate register tables and quick-reset table. */
4392 modified_regs = (char *) alloca (max_reg * sizeof (char));
4393 same_regs = (int *) alloca (max_reg * sizeof (int));
4394 all_reset = (int *) alloca (max_reg * sizeof (int));
4395 for (i = 0; i < max_reg; i++)
4402 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4404 /* Get to a candidate branch insn. */
4405 if (GET_CODE (b1) != JUMP_INSN
4406 || ! condjump_p (b1) || simplejump_p (b1)
4407 || JUMP_LABEL (b1) == 0)
4410 bzero (modified_regs, max_reg * sizeof (char));
4413 bcopy ((char *) all_reset, (char *) same_regs,
4414 max_reg * sizeof (int));
4417 label = JUMP_LABEL (b1);
4419 /* Look for a branch after the target. Record any registers and
4420 memory modified between the target and the branch. Stop when we
4421 get to a label since we can't know what was changed there. */
4422 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4424 if (GET_CODE (b2) == CODE_LABEL)
4427 else if (GET_CODE (b2) == JUMP_INSN)
4429 /* If this is an unconditional jump and is the only use of
4430 its target label, we can follow it. */
4431 if (simplejump_p (b2)
4432 && JUMP_LABEL (b2) != 0
4433 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4435 b2 = JUMP_LABEL (b2);
4442 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4445 if (GET_CODE (b2) == CALL_INSN)
4448 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4449 if (call_used_regs[i] && ! fixed_regs[i]
4450 && i != STACK_POINTER_REGNUM
4451 && i != FRAME_POINTER_REGNUM
4452 && i != HARD_FRAME_POINTER_REGNUM
4453 && i != ARG_POINTER_REGNUM)
4454 modified_regs[i] = 1;
4457 note_stores (PATTERN (b2), mark_modified_reg);
4460 /* Check the next candidate branch insn from the label
4463 || GET_CODE (b2) != JUMP_INSN
4465 || ! condjump_p (b2)
4466 || simplejump_p (b2))
4469 /* Get the comparison codes and operands, reversing the
4470 codes if appropriate. If we don't have comparison codes,
4471 we can't do anything. */
4472 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4473 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4474 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4475 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4476 code1 = reverse_condition (code1);
4478 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4479 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4480 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4481 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4482 code2 = reverse_condition (code2);
4484 /* If they test the same things and knowing that B1 branches
4485 tells us whether or not B2 branches, check if we
4486 can thread the branch. */
4487 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4488 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4489 && (comparison_dominates_p (code1, code2)
4490 || (comparison_dominates_p (code1, reverse_condition (code2))
4491 && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)),
4495 t1 = prev_nonnote_insn (b1);
4496 t2 = prev_nonnote_insn (b2);
4498 while (t1 != 0 && t2 != 0)
4502 /* We have reached the target of the first branch.
4503 If there are no pending register equivalents,
4504 we know that this branch will either always
4505 succeed (if the senses of the two branches are
4506 the same) or always fail (if not). */
4509 if (num_same_regs != 0)
4512 if (comparison_dominates_p (code1, code2))
4513 new_label = JUMP_LABEL (b2);
4515 new_label = get_label_after (b2);
4517 if (JUMP_LABEL (b1) != new_label)
4519 rtx prev = PREV_INSN (new_label);
4521 if (flag_before_loop
4522 && GET_CODE (prev) == NOTE
4523 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4525 /* Don't thread to the loop label. If a loop
4526 label is reused, loop optimization will
4527 be disabled for that loop. */
4528 new_label = gen_label_rtx ();
4529 emit_label_after (new_label, PREV_INSN (prev));
4531 changed |= redirect_jump (b1, new_label);
4536 /* If either of these is not a normal insn (it might be
4537 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4538 have already been skipped above.) Similarly, fail
4539 if the insns are different. */
4540 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4541 || recog_memoized (t1) != recog_memoized (t2)
4542 || ! rtx_equal_for_thread_p (PATTERN (t1),
4546 t1 = prev_nonnote_insn (t1);
4547 t2 = prev_nonnote_insn (t2);
4554 /* This is like RTX_EQUAL_P except that it knows about our handling of
4555 possibly equivalent registers and knows to consider volatile and
4556 modified objects as not equal.
4558 YINSN is the insn containing Y. */
4561 rtx_equal_for_thread_p (x, y, yinsn)
4567 register enum rtx_code code;
4570 code = GET_CODE (x);
4571 /* Rtx's of different codes cannot be equal. */
4572 if (code != GET_CODE (y))
4575 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4576 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4578 if (GET_MODE (x) != GET_MODE (y))
4581 /* For floating-point, consider everything unequal. This is a bit
4582 pessimistic, but this pass would only rarely do anything for FP
4584 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4585 && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math)
4588 /* For commutative operations, the RTX match if the operand match in any
4589 order. Also handle the simple binary and unary cases without a loop. */
4590 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4591 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4592 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4593 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4594 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4595 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4596 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4597 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4598 else if (GET_RTX_CLASS (code) == '1')
4599 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4601 /* Handle special-cases first. */
4605 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4608 /* If neither is user variable or hard register, check for possible
4610 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4611 || REGNO (x) < FIRST_PSEUDO_REGISTER
4612 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4615 if (same_regs[REGNO (x)] == -1)
4617 same_regs[REGNO (x)] = REGNO (y);
4620 /* If this is the first time we are seeing a register on the `Y'
4621 side, see if it is the last use. If not, we can't thread the
4622 jump, so mark it as not equivalent. */
4623 if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn))
4629 return (same_regs[REGNO (x)] == REGNO (y));
4634 /* If memory modified or either volatile, not equivalent.
4635 Else, check address. */
4636 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4639 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4642 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4648 /* Cancel a pending `same_regs' if setting equivalenced registers.
4649 Then process source. */
4650 if (GET_CODE (SET_DEST (x)) == REG
4651 && GET_CODE (SET_DEST (y)) == REG)
4653 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4655 same_regs[REGNO (SET_DEST (x))] = -1;
4658 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4662 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4665 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4668 return XEXP (x, 0) == XEXP (y, 0);
4671 return XSTR (x, 0) == XSTR (y, 0);
4680 fmt = GET_RTX_FORMAT (code);
4681 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4686 if (XWINT (x, i) != XWINT (y, i))
4692 if (XINT (x, i) != XINT (y, i))
4698 /* Two vectors must have the same length. */
4699 if (XVECLEN (x, i) != XVECLEN (y, i))
4702 /* And the corresponding elements must match. */
4703 for (j = 0; j < XVECLEN (x, i); j++)
4704 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4705 XVECEXP (y, i, j), yinsn) == 0)
4710 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4716 if (strcmp (XSTR (x, i), XSTR (y, i)))
4721 /* These are just backpointers, so they don't matter. */
4727 /* It is believed that rtx's at this level will never
4728 contain anything but integers and other rtx's,
4729 except for within LABEL_REFs and SYMBOL_REFs. */
4739 /* Return the insn that NEW can be safely inserted in front of starting at
4740 the jump insn INSN. Return 0 if it is not safe to do this jump
4741 optimization. Note that NEW must contain a single set. */
4744 find_insert_position (insn, new)
4751 /* If NEW does not clobber, it is safe to insert NEW before INSN. */
4752 if (GET_CODE (PATTERN (new)) != PARALLEL)
4755 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
4756 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
4757 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
4764 /* There is a good chance that the previous insn PREV sets the thing
4765 being clobbered (often the CC in a hard reg). If PREV does not
4766 use what NEW sets, we can insert NEW before PREV. */
4768 prev = prev_active_insn (insn);
4769 for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--)
4770 if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER
4771 && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
4773 && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0),
4777 return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev;
4779 #endif /* !HAVE_cc0 */
4781 /* Return 1 if the value of X is unsafe to arbitrarily evaluate, i.e.
4782 might fault on some arguments. This is used in connection with
4783 conditional move optimization. */
4789 register RTX_CODE code = GET_CODE (x);
4796 return ! RTX_UNCHANGING_P (x);
4820 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
4822 && FLOAT_MODE_P (GET_MODE (x)))
4825 switch (GET_RTX_CLASS (code))
4841 fmt = GET_RTX_FORMAT (code);
4842 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4844 if (rtx_unsafe_p (XEXP (x, i)))