1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 88, 89, 91-94, 1995 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This is the jump-optimization pass of the compiler.
22 It is run two or three times: once before cse, sometimes once after cse,
23 and once after reload (before final).
25 jump_optimize deletes unreachable code and labels that are not used.
26 It also deletes jumps that jump to the following insn,
27 and simplifies jumps around unconditional jumps and jumps
28 to unconditional jumps.
30 Each CODE_LABEL has a count of the times it is used
31 stored in the LABEL_NUSES internal field, and each JUMP_INSN
32 has one label that it refers to stored in the
33 JUMP_LABEL internal field. With this we can detect labels that
34 become unused because of the deletion of all the jumps that
35 formerly used them. The JUMP_LABEL info is sometimes looked
38 Optionally, cross-jumping can be done. Currently it is done
39 only the last time (when after reload and before final).
40 In fact, the code for cross-jumping now assumes that register
41 allocation has been done, since it uses `rtx_renumbered_equal_p'.
43 Jump optimization is done after cse when cse's constant-propagation
44 causes jumps to become unconditional or to be deleted.
46 Unreachable loops are not detected here, because the labels
47 have references and the insns appear reachable from the labels.
48 find_basic_blocks in flow.c finds and deletes such loops.
50 The subroutines delete_insn, redirect_jump, and invert_jump are used
51 from other passes as well. */
56 #include "hard-reg-set.h"
58 #include "insn-config.h"
59 #include "insn-flags.h"
63 /* ??? Eventually must record somehow the labels used by jumps
64 from nested functions. */
65 /* Pre-record the next or previous real insn for each label?
66 No, this pass is very fast anyway. */
67 /* Condense consecutive labels?
68 This would make life analysis faster, maybe. */
69 /* Optimize jump y; x: ... y: jumpif... x?
70 Don't know if it is worth bothering with. */
71 /* Optimize two cases of conditional jump to conditional jump?
72 This can never delete any instruction or make anything dead,
73 or even change what is live at any point.
74 So perhaps let combiner do it. */
76 /* Vector indexed by uid.
77 For each CODE_LABEL, index by its uid to get first unconditional jump
78 that jumps to the label.
79 For each JUMP_INSN, index by its uid to get the next unconditional jump
80 that jumps to the same label.
81 Element 0 is the start of a chain of all return insns.
82 (It is safe to use element 0 because insn uid 0 is not used. */
84 static rtx *jump_chain;
86 /* List of labels referred to from initializers.
87 These can never be deleted. */
90 /* Maximum index in jump_chain. */
92 static int max_jump_chain;
94 /* Set nonzero by jump_optimize if control can fall through
95 to the end of the function. */
98 /* Indicates whether death notes are significant in cross jump analysis.
99 Normally they are not significant, because of A and B jump to C,
100 and R dies in A, it must die in B. But this might not be true after
101 stack register conversion, and we must compare death notes in that
104 static int cross_jump_death_matters = 0;
106 static int duplicate_loop_exit_test PROTO((rtx));
107 static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *));
108 static void do_cross_jump PROTO((rtx, rtx, rtx));
109 static int jump_back_p PROTO((rtx, rtx));
110 static int tension_vector_labels PROTO((rtx, int));
111 static void mark_jump_label PROTO((rtx, rtx, int));
112 static void delete_computation PROTO((rtx));
113 static void delete_from_jump_chain PROTO((rtx));
114 static int delete_labelref_insn PROTO((rtx, rtx, int));
115 static void redirect_tablejump PROTO((rtx, rtx));
117 /* Delete no-op jumps and optimize jumps to jumps
118 and jumps around jumps.
119 Delete unused labels and unreachable code.
121 If CROSS_JUMP is 1, detect matching code
122 before a jump and its destination and unify them.
123 If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
125 If NOOP_MOVES is nonzero, delete no-op move insns.
127 If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
128 after regscan, and it is safe to use regno_first_uid and regno_last_uid.
130 If `optimize' is zero, don't change any code,
131 just determine whether control drops off the end of the function.
132 This case occurs when we have -W and not -O.
133 It works because `delete_insn' checks the value of `optimize'
134 and refrains from actually deleting when that is 0. */
137 jump_optimize (f, cross_jump, noop_moves, after_regscan)
143 register rtx insn, next, note;
149 cross_jump_death_matters = (cross_jump == 2);
151 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
152 notes whose labels don't occur in the insn any more. */
154 for (insn = f; insn; insn = NEXT_INSN (insn))
156 if (GET_CODE (insn) == CODE_LABEL)
157 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
158 else if (GET_CODE (insn) == JUMP_INSN)
159 JUMP_LABEL (insn) = 0;
160 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
161 for (note = REG_NOTES (insn); note; note = next)
163 next = XEXP (note, 1);
164 if (REG_NOTE_KIND (note) == REG_LABEL
165 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
166 remove_note (insn, note);
169 if (INSN_UID (insn) > max_uid)
170 max_uid = INSN_UID (insn);
175 /* Delete insns following barriers, up to next label. */
177 for (insn = f; insn;)
179 if (GET_CODE (insn) == BARRIER)
181 insn = NEXT_INSN (insn);
182 while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
184 if (GET_CODE (insn) == NOTE
185 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
186 insn = NEXT_INSN (insn);
188 insn = delete_insn (insn);
190 /* INSN is now the code_label. */
193 insn = NEXT_INSN (insn);
196 /* Leave some extra room for labels and duplicate exit test insns
198 max_jump_chain = max_uid * 14 / 10;
199 jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx));
200 bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx));
202 /* Mark the label each jump jumps to.
203 Combine consecutive labels, and count uses of labels.
205 For each label, make a chain (using `jump_chain')
206 of all the *unconditional* jumps that jump to it;
207 also make a chain of all returns. */
209 for (insn = f; insn; insn = NEXT_INSN (insn))
210 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
211 && ! INSN_DELETED_P (insn))
213 mark_jump_label (PATTERN (insn), insn, cross_jump);
214 if (GET_CODE (insn) == JUMP_INSN)
216 if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
218 jump_chain[INSN_UID (insn)]
219 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
220 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
222 if (GET_CODE (PATTERN (insn)) == RETURN)
224 jump_chain[INSN_UID (insn)] = jump_chain[0];
225 jump_chain[0] = insn;
230 /* Keep track of labels used from static data;
231 they cannot ever be deleted. */
233 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
234 LABEL_NUSES (XEXP (insn, 0))++;
236 /* Delete all labels already not referenced.
237 Also find the last insn. */
240 for (insn = f; insn; )
242 if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0)
243 insn = delete_insn (insn);
247 insn = NEXT_INSN (insn);
253 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
254 If so record that this function can drop off the end. */
260 /* One label can follow the end-note: the return label. */
261 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
262 /* Ordinary insns can follow it if returning a structure. */
263 || GET_CODE (insn) == INSN
264 /* If machine uses explicit RETURN insns, no epilogue,
265 then one of them follows the note. */
266 || (GET_CODE (insn) == JUMP_INSN
267 && GET_CODE (PATTERN (insn)) == RETURN)
268 /* Other kinds of notes can follow also. */
269 || (GET_CODE (insn) == NOTE
270 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
271 insn = PREV_INSN (insn);
274 /* Report if control can fall through at the end of the function. */
275 if (insn && GET_CODE (insn) == NOTE
276 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END
277 && ! INSN_DELETED_P (insn))
280 /* Zero the "deleted" flag of all the "deleted" insns. */
281 for (insn = f; insn; insn = NEXT_INSN (insn))
282 INSN_DELETED_P (insn) = 0;
289 /* If we fall through to the epilogue, see if we can insert a RETURN insn
290 in front of it. If the machine allows it at this point (we might be
291 after reload for a leaf routine), it will improve optimization for it
293 insn = get_last_insn ();
294 while (insn && GET_CODE (insn) == NOTE)
295 insn = PREV_INSN (insn);
297 if (insn && GET_CODE (insn) != BARRIER)
299 emit_jump_insn (gen_return ());
306 for (insn = f; insn; )
308 next = NEXT_INSN (insn);
310 if (GET_CODE (insn) == INSN)
312 register rtx body = PATTERN (insn);
314 /* Combine stack_adjusts with following push_insns. */
316 if (GET_CODE (body) == SET
317 && SET_DEST (body) == stack_pointer_rtx
318 && GET_CODE (SET_SRC (body)) == PLUS
319 && XEXP (SET_SRC (body), 0) == stack_pointer_rtx
320 && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT
321 && INTVAL (XEXP (SET_SRC (body), 1)) > 0)
324 rtx stack_adjust_insn = insn;
325 int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1));
326 int total_pushed = 0;
329 /* Find all successive push insns. */
331 /* Don't convert more than three pushes;
332 that starts adding too many displaced addresses
333 and the whole thing starts becoming a losing
338 p = next_nonnote_insn (p);
339 if (p == 0 || GET_CODE (p) != INSN)
342 if (GET_CODE (pbody) != SET)
344 dest = SET_DEST (pbody);
345 /* Allow a no-op move between the adjust and the push. */
346 if (GET_CODE (dest) == REG
347 && GET_CODE (SET_SRC (pbody)) == REG
348 && REGNO (dest) == REGNO (SET_SRC (pbody)))
350 if (! (GET_CODE (dest) == MEM
351 && GET_CODE (XEXP (dest, 0)) == POST_INC
352 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
355 if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)))
356 > stack_adjust_amount)
358 total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
361 /* Discard the amount pushed from the stack adjust;
362 maybe eliminate it entirely. */
363 if (total_pushed >= stack_adjust_amount)
365 delete_computation (stack_adjust_insn);
366 total_pushed = stack_adjust_amount;
369 XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1)
370 = GEN_INT (stack_adjust_amount - total_pushed);
372 /* Change the appropriate push insns to ordinary stores. */
374 while (total_pushed > 0)
377 p = next_nonnote_insn (p);
378 if (GET_CODE (p) != INSN)
381 if (GET_CODE (pbody) == SET)
383 dest = SET_DEST (pbody);
384 if (! (GET_CODE (dest) == MEM
385 && GET_CODE (XEXP (dest, 0)) == POST_INC
386 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx))
388 total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody)));
389 /* If this push doesn't fully fit in the space
390 of the stack adjust that we deleted,
391 make another stack adjust here for what we
392 didn't use up. There should be peepholes
393 to recognize the resulting sequence of insns. */
394 if (total_pushed < 0)
396 emit_insn_before (gen_add2_insn (stack_pointer_rtx,
397 GEN_INT (- total_pushed)),
402 = plus_constant (stack_pointer_rtx, total_pushed);
407 /* Detect and delete no-op move instructions
408 resulting from not allocating a parameter in a register. */
410 if (GET_CODE (body) == SET
411 && (SET_DEST (body) == SET_SRC (body)
412 || (GET_CODE (SET_DEST (body)) == MEM
413 && GET_CODE (SET_SRC (body)) == MEM
414 && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
415 && ! (GET_CODE (SET_DEST (body)) == MEM
416 && MEM_VOLATILE_P (SET_DEST (body)))
417 && ! (GET_CODE (SET_SRC (body)) == MEM
418 && MEM_VOLATILE_P (SET_SRC (body))))
419 delete_computation (insn);
421 /* Detect and ignore no-op move instructions
422 resulting from smart or fortuitous register allocation. */
424 else if (GET_CODE (body) == SET)
426 int sreg = true_regnum (SET_SRC (body));
427 int dreg = true_regnum (SET_DEST (body));
429 if (sreg == dreg && sreg >= 0)
431 else if (sreg >= 0 && dreg >= 0)
434 rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
435 sreg, NULL_PTR, dreg,
436 GET_MODE (SET_SRC (body)));
438 #ifdef PRESERVE_DEATH_INFO_REGNO_P
439 /* Deleting insn could lose a death-note for SREG or DREG
440 so don't do it if final needs accurate death-notes. */
441 if (! PRESERVE_DEATH_INFO_REGNO_P (sreg)
442 && ! PRESERVE_DEATH_INFO_REGNO_P (dreg))
445 /* DREG may have been the target of a REG_DEAD note in
446 the insn which makes INSN redundant. If so, reorg
447 would still think it is dead. So search for such a
448 note and delete it if we find it. */
449 for (trial = prev_nonnote_insn (insn);
450 trial && GET_CODE (trial) != CODE_LABEL;
451 trial = prev_nonnote_insn (trial))
452 if (find_regno_note (trial, REG_DEAD, dreg))
454 remove_death (dreg, trial);
459 && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
463 else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
464 && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
466 GET_MODE (SET_DEST (body))))
468 /* This handles the case where we have two consecutive
469 assignments of the same constant to pseudos that didn't
470 get a hard reg. Each SET from the constant will be
471 converted into a SET of the spill register and an
472 output reload will be made following it. This produces
473 two loads of the same constant into the same spill
478 /* Look back for a death note for the first reg.
479 If there is one, it is no longer accurate. */
480 while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
482 if ((GET_CODE (in_insn) == INSN
483 || GET_CODE (in_insn) == JUMP_INSN)
484 && find_regno_note (in_insn, REG_DEAD, dreg))
486 remove_death (dreg, in_insn);
489 in_insn = PREV_INSN (in_insn);
492 /* Delete the second load of the value. */
496 else if (GET_CODE (body) == PARALLEL)
498 /* If each part is a set between two identical registers or
499 a USE or CLOBBER, delete the insn. */
503 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
505 tem = XVECEXP (body, 0, i);
506 if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
509 if (GET_CODE (tem) != SET
510 || (sreg = true_regnum (SET_SRC (tem))) < 0
511 || (dreg = true_regnum (SET_DEST (tem))) < 0
519 /* Also delete insns to store bit fields if they are no-ops. */
520 /* Not worth the hair to detect this in the big-endian case. */
521 else if (! BYTES_BIG_ENDIAN
522 && GET_CODE (body) == SET
523 && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
524 && XEXP (SET_DEST (body), 2) == const0_rtx
525 && XEXP (SET_DEST (body), 0) == SET_SRC (body)
526 && ! (GET_CODE (SET_SRC (body)) == MEM
527 && MEM_VOLATILE_P (SET_SRC (body))))
533 /* If we haven't yet gotten to reload and we have just run regscan,
534 delete any insn that sets a register that isn't used elsewhere.
535 This helps some of the optimizations below by having less insns
536 being jumped around. */
538 if (! reload_completed && after_regscan)
539 for (insn = f; insn; insn = next)
541 rtx set = single_set (insn);
543 next = NEXT_INSN (insn);
545 if (set && GET_CODE (SET_DEST (set)) == REG
546 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
547 && regno_first_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
548 /* We use regno_last_note_uid so as not to delete the setting
549 of a reg that's used in notes. A subsequent optimization
550 might arrange to use that reg for real. */
551 && regno_last_note_uid[REGNO (SET_DEST (set))] == INSN_UID (insn)
552 && ! side_effects_p (SET_SRC (set))
553 && ! find_reg_note (insn, REG_RETVAL, 0))
557 /* Now iterate optimizing jumps until nothing changes over one pass. */
563 for (insn = f; insn; insn = next)
566 rtx temp, temp1, temp2, temp3, temp4, temp5, temp6;
568 int this_is_simplejump, this_is_condjump, reversep;
569 int this_is_condjump_in_parallel;
571 /* If NOT the first iteration, if this is the last jump pass
572 (just before final), do the special peephole optimizations.
573 Avoiding the first iteration gives ordinary jump opts
574 a chance to work before peephole opts. */
576 if (reload_completed && !first && !flag_no_peephole)
577 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
581 /* That could have deleted some insns after INSN, so check now
582 what the following insn is. */
584 next = NEXT_INSN (insn);
586 /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
587 jump. Try to optimize by duplicating the loop exit test if so.
588 This is only safe immediately after regscan, because it uses
589 the values of regno_first_uid and regno_last_uid. */
590 if (after_regscan && GET_CODE (insn) == NOTE
591 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
592 && (temp1 = next_nonnote_insn (insn)) != 0
593 && simplejump_p (temp1))
595 temp = PREV_INSN (insn);
596 if (duplicate_loop_exit_test (insn))
599 next = NEXT_INSN (temp);
604 if (GET_CODE (insn) != JUMP_INSN)
607 this_is_simplejump = simplejump_p (insn);
608 this_is_condjump = condjump_p (insn);
609 this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
611 /* Tension the labels in dispatch tables. */
613 if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
614 changed |= tension_vector_labels (PATTERN (insn), 0);
615 if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
616 changed |= tension_vector_labels (PATTERN (insn), 1);
618 /* If a dispatch table always goes to the same place,
619 get rid of it and replace the insn that uses it. */
621 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
622 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
625 rtx pat = PATTERN (insn);
626 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
627 int len = XVECLEN (pat, diff_vec_p);
628 rtx dispatch = prev_real_insn (insn);
630 for (i = 0; i < len; i++)
631 if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
632 != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
636 && GET_CODE (dispatch) == JUMP_INSN
637 && JUMP_LABEL (dispatch) != 0
638 /* Don't mess with a casesi insn. */
639 && !(GET_CODE (PATTERN (dispatch)) == SET
640 && (GET_CODE (SET_SRC (PATTERN (dispatch)))
642 && next_real_insn (JUMP_LABEL (dispatch)) == insn)
644 redirect_tablejump (dispatch,
645 XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
650 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
652 /* If a jump references the end of the function, try to turn
653 it into a RETURN insn, possibly a conditional one. */
654 if (JUMP_LABEL (insn)
655 && (next_active_insn (JUMP_LABEL (insn)) == 0
656 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
658 changed |= redirect_jump (insn, NULL_RTX);
660 /* Detect jump to following insn. */
661 if (reallabelprev == insn && condjump_p (insn))
663 next = next_real_insn (JUMP_LABEL (insn));
669 /* If we have an unconditional jump preceded by a USE, try to put
670 the USE before the target and jump there. This simplifies many
671 of the optimizations below since we don't have to worry about
672 dealing with these USE insns. We only do this if the label
673 being branch to already has the identical USE or if code
674 never falls through to that label. */
676 if (this_is_simplejump
677 && (temp = prev_nonnote_insn (insn)) != 0
678 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE
679 && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
680 && (GET_CODE (temp1) == BARRIER
681 || (GET_CODE (temp1) == INSN
682 && rtx_equal_p (PATTERN (temp), PATTERN (temp1)))))
684 if (GET_CODE (temp1) == BARRIER)
686 emit_insn_after (PATTERN (temp), temp1);
687 temp1 = NEXT_INSN (temp1);
691 redirect_jump (insn, get_label_before (temp1));
692 reallabelprev = prev_real_insn (temp1);
696 /* Simplify if (...) x = a; else x = b; by converting it
697 to x = b; if (...) x = a;
698 if B is sufficiently simple, the test doesn't involve X,
699 and nothing in the test modifies B or X.
701 If we have small register classes, we also can't do this if X
704 If the "x = b;" insn has any REG_NOTES, we don't do this because
705 of the possibility that we are running after CSE and there is a
706 REG_EQUAL note that is only valid if the branch has already been
707 taken. If we move the insn with the REG_EQUAL note, we may
708 fold the comparison to always be false in a later CSE pass.
709 (We could also delete the REG_NOTES when moving the insn, but it
710 seems simpler to not move it.) An exception is that we can move
711 the insn if the only note is a REG_EQUAL or REG_EQUIV whose
712 value is the same as "b".
714 INSN is the branch over the `else' part.
718 TEMP to the jump insn preceding "x = a;"
720 TEMP2 to the insn that sets "x = b;"
721 TEMP3 to the insn that sets "x = a;"
722 TEMP4 to the set of "x = b"; */
724 if (this_is_simplejump
725 && (temp3 = prev_active_insn (insn)) != 0
726 && GET_CODE (temp3) == INSN
727 && (temp4 = single_set (temp3)) != 0
728 && GET_CODE (temp1 = SET_DEST (temp4)) == REG
729 #ifdef SMALL_REGISTER_CLASSES
730 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
732 && (temp2 = next_active_insn (insn)) != 0
733 && GET_CODE (temp2) == INSN
734 && (temp4 = single_set (temp2)) != 0
735 && rtx_equal_p (SET_DEST (temp4), temp1)
736 && (GET_CODE (SET_SRC (temp4)) == REG
737 || GET_CODE (SET_SRC (temp4)) == SUBREG
738 || CONSTANT_P (SET_SRC (temp4)))
739 && (REG_NOTES (temp2) == 0
740 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
741 || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
742 && XEXP (REG_NOTES (temp2), 1) == 0
743 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
745 && (temp = prev_active_insn (temp3)) != 0
746 && condjump_p (temp) && ! simplejump_p (temp)
747 /* TEMP must skip over the "x = a;" insn */
748 && prev_real_insn (JUMP_LABEL (temp)) == insn
749 && no_labels_between_p (insn, JUMP_LABEL (temp))
750 /* There must be no other entries to the "x = b;" insn. */
751 && no_labels_between_p (JUMP_LABEL (temp), temp2)
752 /* INSN must either branch to the insn after TEMP2 or the insn
753 after TEMP2 must branch to the same place as INSN. */
754 && (reallabelprev == temp2
755 || ((temp5 = next_active_insn (temp2)) != 0
756 && simplejump_p (temp5)
757 && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
759 /* The test expression, X, may be a complicated test with
760 multiple branches. See if we can find all the uses of
761 the label that TEMP branches to without hitting a CALL_INSN
762 or a jump to somewhere else. */
763 rtx target = JUMP_LABEL (temp);
764 int nuses = LABEL_NUSES (target);
767 /* Set P to the first jump insn that goes around "x = a;". */
768 for (p = temp; nuses && p; p = prev_nonnote_insn (p))
770 if (GET_CODE (p) == JUMP_INSN)
772 if (condjump_p (p) && ! simplejump_p (p)
773 && JUMP_LABEL (p) == target)
782 else if (GET_CODE (p) == CALL_INSN)
787 /* We cannot insert anything between a set of cc and its use
788 so if P uses cc0, we must back up to the previous insn. */
789 q = prev_nonnote_insn (p);
790 if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
791 && sets_cc0_p (PATTERN (q)))
798 /* If we found all the uses and there was no data conflict, we
799 can move the assignment unless we can branch into the middle
802 && no_labels_between_p (p, insn)
803 && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
804 && ! reg_set_between_p (temp1, p, temp3)
805 && (GET_CODE (SET_SRC (temp4)) == CONST_INT
806 || ! reg_set_between_p (SET_SRC (temp4), p, temp2)))
808 emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
811 /* Set NEXT to an insn that we know won't go away. */
812 next = next_active_insn (insn);
814 /* Delete the jump around the set. Note that we must do
815 this before we redirect the test jumps so that it won't
816 delete the code immediately following the assignment
817 we moved (which might be a jump). */
821 /* We either have two consecutive labels or a jump to
822 a jump, so adjust all the JUMP_INSNs to branch to where
824 for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
825 if (GET_CODE (p) == JUMP_INSN)
826 redirect_jump (p, target);
834 /* If we have if (...) x = exp; and branches are expensive,
835 EXP is a single insn, does not have any side effects, cannot
836 trap, and is not too costly, convert this to
837 t = exp; if (...) x = t;
839 Don't do this when we have CC0 because it is unlikely to help
840 and we'd need to worry about where to place the new insn and
841 the potential for conflicts. We also can't do this when we have
842 notes on the insn for the same reason as above.
846 TEMP to the "x = exp;" insn.
847 TEMP1 to the single set in the "x = exp; insn.
850 if (! reload_completed
851 && this_is_condjump && ! this_is_simplejump
853 && (temp = next_nonnote_insn (insn)) != 0
854 && GET_CODE (temp) == INSN
855 && REG_NOTES (temp) == 0
856 && (reallabelprev == temp
857 || ((temp2 = next_active_insn (temp)) != 0
858 && simplejump_p (temp2)
859 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
860 && (temp1 = single_set (temp)) != 0
861 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
862 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
863 #ifdef SMALL_REGISTER_CLASSES
864 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
866 && GET_CODE (SET_SRC (temp1)) != REG
867 && GET_CODE (SET_SRC (temp1)) != SUBREG
868 && GET_CODE (SET_SRC (temp1)) != CONST_INT
869 && ! side_effects_p (SET_SRC (temp1))
870 && ! may_trap_p (SET_SRC (temp1))
871 && rtx_cost (SET_SRC (temp1)) < 10)
873 rtx new = gen_reg_rtx (GET_MODE (temp2));
875 if (validate_change (temp, &SET_DEST (temp1), new, 0))
877 next = emit_insn_after (gen_move_insn (temp2, new), insn);
878 emit_insn_after_with_line_notes (PATTERN (temp),
879 PREV_INSN (insn), temp);
881 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
885 /* Similarly, if it takes two insns to compute EXP but they
886 have the same destination. Here TEMP3 will be the second
887 insn and TEMP4 the SET from that insn. */
889 if (! reload_completed
890 && this_is_condjump && ! this_is_simplejump
892 && (temp = next_nonnote_insn (insn)) != 0
893 && GET_CODE (temp) == INSN
894 && REG_NOTES (temp) == 0
895 && (temp3 = next_nonnote_insn (temp)) != 0
896 && GET_CODE (temp3) == INSN
897 && REG_NOTES (temp3) == 0
898 && (reallabelprev == temp3
899 || ((temp2 = next_active_insn (temp3)) != 0
900 && simplejump_p (temp2)
901 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
902 && (temp1 = single_set (temp)) != 0
903 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
904 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
905 #ifdef SMALL_REGISTER_CLASSES
906 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
908 && ! side_effects_p (SET_SRC (temp1))
909 && ! may_trap_p (SET_SRC (temp1))
910 && rtx_cost (SET_SRC (temp1)) < 10
911 && (temp4 = single_set (temp3)) != 0
912 && rtx_equal_p (SET_DEST (temp4), temp2)
913 && ! side_effects_p (SET_SRC (temp4))
914 && ! may_trap_p (SET_SRC (temp4))
915 && rtx_cost (SET_SRC (temp4)) < 10)
917 rtx new = gen_reg_rtx (GET_MODE (temp2));
919 if (validate_change (temp, &SET_DEST (temp1), new, 0))
921 next = emit_insn_after (gen_move_insn (temp2, new), insn);
922 emit_insn_after_with_line_notes (PATTERN (temp),
923 PREV_INSN (insn), temp);
924 emit_insn_after_with_line_notes
925 (replace_rtx (PATTERN (temp3), temp2, new),
926 PREV_INSN (insn), temp3);
929 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
933 /* Finally, handle the case where two insns are used to
934 compute EXP but a temporary register is used. Here we must
935 ensure that the temporary register is not used anywhere else. */
937 if (! reload_completed
939 && this_is_condjump && ! this_is_simplejump
941 && (temp = next_nonnote_insn (insn)) != 0
942 && GET_CODE (temp) == INSN
943 && REG_NOTES (temp) == 0
944 && (temp3 = next_nonnote_insn (temp)) != 0
945 && GET_CODE (temp3) == INSN
946 && REG_NOTES (temp3) == 0
947 && (reallabelprev == temp3
948 || ((temp2 = next_active_insn (temp3)) != 0
949 && simplejump_p (temp2)
950 && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
951 && (temp1 = single_set (temp)) != 0
952 && (temp5 = SET_DEST (temp1),
953 (GET_CODE (temp5) == REG
954 || (GET_CODE (temp5) == SUBREG
955 && (temp5 = SUBREG_REG (temp5),
956 GET_CODE (temp5) == REG))))
957 && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
958 && regno_first_uid[REGNO (temp5)] == INSN_UID (temp)
959 && regno_last_uid[REGNO (temp5)] == INSN_UID (temp3)
960 && ! side_effects_p (SET_SRC (temp1))
961 && ! may_trap_p (SET_SRC (temp1))
962 && rtx_cost (SET_SRC (temp1)) < 10
963 && (temp4 = single_set (temp3)) != 0
964 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
965 && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
966 #ifdef SMALL_REGISTER_CLASSES
967 && REGNO (temp2) >= FIRST_PSEUDO_REGISTER
969 && rtx_equal_p (SET_DEST (temp4), temp2)
970 && ! side_effects_p (SET_SRC (temp4))
971 && ! may_trap_p (SET_SRC (temp4))
972 && rtx_cost (SET_SRC (temp4)) < 10)
974 rtx new = gen_reg_rtx (GET_MODE (temp2));
976 if (validate_change (temp3, &SET_DEST (temp4), new, 0))
978 next = emit_insn_after (gen_move_insn (temp2, new), insn);
979 emit_insn_after_with_line_notes (PATTERN (temp),
980 PREV_INSN (insn), temp);
981 emit_insn_after_with_line_notes (PATTERN (temp3),
982 PREV_INSN (insn), temp3);
985 reallabelprev = prev_active_insn (JUMP_LABEL (insn));
988 #endif /* HAVE_cc0 */
990 /* Try to use a conditional move (if the target has them), or a
991 store-flag insn. The general case is:
993 1) x = a; if (...) x = b; and
996 If the jump would be faster, the machine should not have defined
997 the movcc or scc insns!. These cases are often made by the
998 previous optimization.
1000 The second case is treated as x = x; if (...) x = b;.
1002 INSN here is the jump around the store. We set:
1004 TEMP to the "x = b;" insn.
1007 TEMP3 to A (X in the second case).
1008 TEMP4 to the condition being tested.
1009 TEMP5 to the earliest insn used to find the condition. */
1011 if (/* We can't do this after reload has completed. */
1013 && this_is_condjump && ! this_is_simplejump
1014 /* Set TEMP to the "x = b;" insn. */
1015 && (temp = next_nonnote_insn (insn)) != 0
1016 && GET_CODE (temp) == INSN
1017 && GET_CODE (PATTERN (temp)) == SET
1018 && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG
1019 #ifdef SMALL_REGISTER_CLASSES
1020 && REGNO (temp1) >= FIRST_PSEUDO_REGISTER
1022 && (GET_CODE (temp2 = SET_SRC (PATTERN (temp))) == REG
1023 || GET_CODE (temp2) == SUBREG
1024 /* ??? How about floating point constants? */
1025 || GET_CODE (temp2) == CONST_INT)
1026 /* Allow either form, but prefer the former if both apply.
1027 There is no point in using the old value of TEMP1 if
1028 it is a register, since cse will alias them. It can
1029 lose if the old value were a hard register since CSE
1030 won't replace hard registers. */
1031 && (((temp3 = reg_set_last (temp1, insn)) != 0)
1032 /* Make the latter case look like x = x; if (...) x = b; */
1033 || (temp3 = temp1, 1))
1034 /* INSN must either branch to the insn after TEMP or the insn
1035 after TEMP must branch to the same place as INSN. */
1036 && (reallabelprev == temp
1037 || ((temp4 = next_active_insn (temp)) != 0
1038 && simplejump_p (temp4)
1039 && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
1040 && (temp4 = get_condition (insn, &temp5)) != 0
1041 /* We must be comparing objects whose modes imply the size.
1042 We could handle BLKmode if (1) emit_store_flag could
1043 and (2) we could find the size reliably. */
1044 && GET_MODE (XEXP (temp4, 0)) != BLKmode
1045 /* No point in doing any of this if branches are cheap or we
1046 don't have conditional moves. */
1047 && (BRANCH_COST >= 2
1048 #ifdef HAVE_conditional_move
1053 /* If the previous insn sets CC0 and something else, we can't
1054 do this since we are going to delete that insn. */
1056 && ! ((temp6 = prev_nonnote_insn (insn)) != 0
1057 && GET_CODE (temp6) == INSN
1058 && (sets_cc0_p (PATTERN (temp6)) == -1
1059 || (sets_cc0_p (PATTERN (temp6)) == 1
1060 && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
1064 #ifdef HAVE_conditional_move
1065 /* First try a conditional move. */
1067 enum rtx_code code = GET_CODE (temp4);
1069 rtx cond0, cond1, aval, bval;
1072 /* Copy the compared variables into cond0 and cond1, so that
1073 any side effects performed in or after the old comparison,
1074 will not affect our compare which will come later. */
1075 /* ??? Is it possible to just use the comparison in the jump
1076 insn? After all, we're going to delete it. We'd have
1077 to modify emit_conditional_move to take a comparison rtx
1078 instead or write a new function. */
1079 cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
1080 /* We want the target to be able to simplify comparisons with
1081 zero (and maybe other constants as well), so don't create
1082 pseudos for them. There's no need to either. */
1083 if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
1084 || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
1085 cond1 = XEXP (temp4, 1);
1087 cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
1093 target = emit_conditional_move (var, code,
1094 cond0, cond1, VOIDmode,
1095 aval, bval, GET_MODE (var),
1096 (code == LTU || code == GEU
1097 || code == LEU || code == GTU));
1103 /* Save the conditional move sequence but don't emit it
1104 yet. On some machines, like the alpha, it is possible
1105 that temp5 == insn, so next generate the sequence that
1106 saves the compared values and then emit both
1107 sequences ensuring seq1 occurs before seq2. */
1108 seq2 = get_insns ();
1111 /* Now that we can't fail, generate the copy insns that
1112 preserve the compared values. */
1114 emit_move_insn (cond0, XEXP (temp4, 0));
1115 if (cond1 != XEXP (temp4, 1))
1116 emit_move_insn (cond1, XEXP (temp4, 1));
1117 seq1 = get_insns ();
1120 emit_insns_before (seq1, temp5);
1121 emit_insns_before (seq2, insn);
1123 /* ??? We can also delete the insn that sets X to A.
1124 Flow will do it too though. */
1126 next = NEXT_INSN (insn);
1136 /* That didn't work, try a store-flag insn.
1138 We further divide the cases into:
1140 1) x = a; if (...) x = b; and either A or B is zero,
1141 2) if (...) x = 0; and jumps are expensive,
1142 3) x = a; if (...) x = b; and A and B are constants where all
1143 the set bits in A are also set in B and jumps are expensive,
1144 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
1146 5) if (...) x = b; if jumps are even more expensive. */
1148 if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
1149 && ((GET_CODE (temp3) == CONST_INT)
1150 /* Make the latter case look like
1151 x = x; if (...) x = 0; */
1154 && temp2 == const0_rtx)
1155 || BRANCH_COST >= 3)))
1156 /* If B is zero, OK; if A is zero, can only do (1) if we
1157 can reverse the condition. See if (3) applies possibly
1158 by reversing the condition. Prefer reversing to (4) when
1159 branches are very expensive. */
1160 && ((reversep = 0, temp2 == const0_rtx)
1161 || (temp3 == const0_rtx
1162 && (reversep = can_reverse_comparison_p (temp4, insn)))
1163 || (BRANCH_COST >= 2
1164 && GET_CODE (temp2) == CONST_INT
1165 && GET_CODE (temp3) == CONST_INT
1166 && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
1167 || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
1168 && (reversep = can_reverse_comparison_p (temp4,
1170 || BRANCH_COST >= 3)
1173 enum rtx_code code = GET_CODE (temp4);
1174 rtx uval, cval, var = temp1;
1178 /* If necessary, reverse the condition. */
1180 code = reverse_condition (code), uval = temp2, cval = temp3;
1182 uval = temp3, cval = temp2;
1184 /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
1185 is the constant 1, it is best to just compute the result
1186 directly. If UVAL is constant and STORE_FLAG_VALUE
1187 includes all of its bits, it is best to compute the flag
1188 value unnormalized and `and' it with UVAL. Otherwise,
1189 normalize to -1 and `and' with UVAL. */
1190 normalizep = (cval != const0_rtx ? -1
1191 : (uval == const1_rtx ? 1
1192 : (GET_CODE (uval) == CONST_INT
1193 && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
1196 /* We will be putting the store-flag insn immediately in
1197 front of the comparison that was originally being done,
1198 so we know all the variables in TEMP4 will be valid.
1199 However, this might be in front of the assignment of
1200 A to VAR. If it is, it would clobber the store-flag
1201 we will be emitting.
1203 Therefore, emit into a temporary which will be copied to
1204 VAR immediately after TEMP. */
1207 target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
1208 XEXP (temp4, 0), XEXP (temp4, 1),
1210 (code == LTU || code == LEU
1211 || code == GEU || code == GTU),
1221 /* Put the store-flag insns in front of the first insn
1222 used to compute the condition to ensure that we
1223 use the same values of them as the current
1224 comparison. However, the remainder of the insns we
1225 generate will be placed directly in front of the
1226 jump insn, in case any of the pseudos we use
1227 are modified earlier. */
1229 emit_insns_before (seq, temp5);
1233 /* Both CVAL and UVAL are non-zero. */
1234 if (cval != const0_rtx && uval != const0_rtx)
1238 tem1 = expand_and (uval, target, NULL_RTX);
1239 if (GET_CODE (cval) == CONST_INT
1240 && GET_CODE (uval) == CONST_INT
1241 && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
1245 tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
1246 target, NULL_RTX, 0);
1247 tem2 = expand_and (cval, tem2,
1248 (GET_CODE (tem2) == REG
1252 /* If we usually make new pseudos, do so here. This
1253 turns out to help machines that have conditional
1255 /* ??? Conditional moves have already been handled.
1256 This may be obsolete. */
1258 if (flag_expensive_optimizations)
1261 target = expand_binop (GET_MODE (var), ior_optab,
1265 else if (normalizep != 1)
1267 /* We know that either CVAL or UVAL is zero. If
1268 UVAL is zero, negate TARGET and `and' with CVAL.
1269 Otherwise, `and' with UVAL. */
1270 if (uval == const0_rtx)
1272 target = expand_unop (GET_MODE (var), one_cmpl_optab,
1273 target, NULL_RTX, 0);
1277 target = expand_and (uval, target,
1278 (GET_CODE (target) == REG
1279 && ! preserve_subexpressions_p ()
1280 ? target : NULL_RTX));
1283 emit_move_insn (var, target);
1287 /* If INSN uses CC0, we must not separate it from the
1288 insn that sets cc0. */
1289 if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
1290 before = prev_nonnote_insn (before);
1292 emit_insns_before (seq, before);
1295 next = NEXT_INSN (insn);
1305 /* If branches are expensive, convert
1306 if (foo) bar++; to bar += (foo != 0);
1307 and similarly for "bar--;"
1309 INSN is the conditional branch around the arithmetic. We set:
1311 TEMP is the arithmetic insn.
1312 TEMP1 is the SET doing the arithmetic.
1313 TEMP2 is the operand being incremented or decremented.
1314 TEMP3 to the condition being tested.
1315 TEMP4 to the earliest insn used to find the condition. */
1317 if ((BRANCH_COST >= 2
1325 && ! reload_completed
1326 && this_is_condjump && ! this_is_simplejump
1327 && (temp = next_nonnote_insn (insn)) != 0
1328 && (temp1 = single_set (temp)) != 0
1329 && (temp2 = SET_DEST (temp1),
1330 GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
1331 && GET_CODE (SET_SRC (temp1)) == PLUS
1332 && (XEXP (SET_SRC (temp1), 1) == const1_rtx
1333 || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
1334 && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
1335 && ! side_effects_p (temp2)
1336 && ! may_trap_p (temp2)
1337 /* INSN must either branch to the insn after TEMP or the insn
1338 after TEMP must branch to the same place as INSN. */
1339 && (reallabelprev == temp
1340 || ((temp3 = next_active_insn (temp)) != 0
1341 && simplejump_p (temp3)
1342 && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
1343 && (temp3 = get_condition (insn, &temp4)) != 0
1344 /* We must be comparing objects whose modes imply the size.
1345 We could handle BLKmode if (1) emit_store_flag could
1346 and (2) we could find the size reliably. */
1347 && GET_MODE (XEXP (temp3, 0)) != BLKmode
1348 && can_reverse_comparison_p (temp3, insn))
1350 rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
1351 enum rtx_code code = reverse_condition (GET_CODE (temp3));
1355 /* It must be the case that TEMP2 is not modified in the range
1356 [TEMP4, INSN). The one exception we make is if the insn
1357 before INSN sets TEMP2 to something which is also unchanged
1358 in that range. In that case, we can move the initialization
1359 into our sequence. */
1361 if ((temp5 = prev_active_insn (insn)) != 0
1362 && GET_CODE (temp5) == INSN
1363 && (temp6 = single_set (temp5)) != 0
1364 && rtx_equal_p (temp2, SET_DEST (temp6))
1365 && (CONSTANT_P (SET_SRC (temp6))
1366 || GET_CODE (SET_SRC (temp6)) == REG
1367 || GET_CODE (SET_SRC (temp6)) == SUBREG))
1369 emit_insn (PATTERN (temp5));
1371 init = SET_SRC (temp6);
1374 if (CONSTANT_P (init)
1375 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
1376 target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
1377 XEXP (temp3, 0), XEXP (temp3, 1),
1379 (code == LTU || code == LEU
1380 || code == GTU || code == GEU), 1);
1382 /* If we can do the store-flag, do the addition or
1386 target = expand_binop (GET_MODE (temp2),
1387 (XEXP (SET_SRC (temp1), 1) == const1_rtx
1388 ? add_optab : sub_optab),
1389 temp2, target, temp2, 0, OPTAB_WIDEN);
1393 /* Put the result back in temp2 in case it isn't already.
1394 Then replace the jump, possible a CC0-setting insn in
1395 front of the jump, and TEMP, with the sequence we have
1398 if (target != temp2)
1399 emit_move_insn (temp2, target);
1404 emit_insns_before (seq, temp4);
1408 delete_insn (init_insn);
1410 next = NEXT_INSN (insn);
1412 delete_insn (prev_nonnote_insn (insn));
1422 /* Simplify if (...) x = 1; else {...} if (x) ...
1423 We recognize this case scanning backwards as well.
1425 TEMP is the assignment to x;
1426 TEMP1 is the label at the head of the second if. */
1427 /* ?? This should call get_condition to find the values being
1428 compared, instead of looking for a COMPARE insn when HAVE_cc0
1429 is not defined. This would allow it to work on the m88k. */
1430 /* ?? This optimization is only safe before cse is run if HAVE_cc0
1431 is not defined and the condition is tested by a separate compare
1432 insn. This is because the code below assumes that the result
1433 of the compare dies in the following branch.
1435 Not only that, but there might be other insns between the
1436 compare and branch whose results are live. Those insns need
1439 A way to fix this is to move the insns at JUMP_LABEL (insn)
1440 to before INSN. If we are running before flow, they will
1441 be deleted if they aren't needed. But this doesn't work
1444 This is really a special-case of jump threading, anyway. The
1445 right thing to do is to replace this and jump threading with
1446 much simpler code in cse.
1448 This code has been turned off in the non-cc0 case in the
1452 else if (this_is_simplejump
1453 /* Safe to skip USE and CLOBBER insns here
1454 since they will not be deleted. */
1455 && (temp = prev_active_insn (insn))
1456 && no_labels_between_p (temp, insn)
1457 && GET_CODE (temp) == INSN
1458 && GET_CODE (PATTERN (temp)) == SET
1459 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1460 && CONSTANT_P (SET_SRC (PATTERN (temp)))
1461 && (temp1 = next_active_insn (JUMP_LABEL (insn)))
1462 /* If we find that the next value tested is `x'
1463 (TEMP1 is the insn where this happens), win. */
1464 && GET_CODE (temp1) == INSN
1465 && GET_CODE (PATTERN (temp1)) == SET
1467 /* Does temp1 `tst' the value of x? */
1468 && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
1469 && SET_DEST (PATTERN (temp1)) == cc0_rtx
1470 && (temp1 = next_nonnote_insn (temp1))
1472 /* Does temp1 compare the value of x against zero? */
1473 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1474 && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
1475 && (XEXP (SET_SRC (PATTERN (temp1)), 0)
1476 == SET_DEST (PATTERN (temp)))
1477 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1478 && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1480 && condjump_p (temp1))
1482 /* Get the if_then_else from the condjump. */
1483 rtx choice = SET_SRC (PATTERN (temp1));
1484 if (GET_CODE (choice) == IF_THEN_ELSE)
1486 enum rtx_code code = GET_CODE (XEXP (choice, 0));
1487 rtx val = SET_SRC (PATTERN (temp));
1489 = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
1493 if (cond == const_true_rtx)
1494 ultimate = XEXP (choice, 1);
1495 else if (cond == const0_rtx)
1496 ultimate = XEXP (choice, 2);
1500 if (ultimate == pc_rtx)
1501 ultimate = get_label_after (temp1);
1502 else if (ultimate && GET_CODE (ultimate) != RETURN)
1503 ultimate = XEXP (ultimate, 0);
1506 changed |= redirect_jump (insn, ultimate);
1512 /* @@ This needs a bit of work before it will be right.
1514 Any type of comparison can be accepted for the first and
1515 second compare. When rewriting the first jump, we must
1516 compute the what conditions can reach label3, and use the
1517 appropriate code. We can not simply reverse/swap the code
1518 of the first jump. In some cases, the second jump must be
1522 < == converts to > ==
1523 < != converts to == >
1526 If the code is written to only accept an '==' test for the second
1527 compare, then all that needs to be done is to swap the condition
1528 of the first branch.
1530 It is questionable whether we want this optimization anyways,
1531 since if the user wrote code like this because he/she knew that
1532 the jump to label1 is taken most of the time, then rewriting
1533 this gives slower code. */
1534 /* @@ This should call get_condition to find the values being
1535 compared, instead of looking for a COMPARE insn when HAVE_cc0
1536 is not defined. This would allow it to work on the m88k. */
1537 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1538 is not defined and the condition is tested by a separate compare
1539 insn. This is because the code below assumes that the result
1540 of the compare dies in the following branch. */
1542 /* Simplify test a ~= b
1556 where ~= is an inequality, e.g. >, and ~~= is the swapped
1559 We recognize this case scanning backwards.
1561 TEMP is the conditional jump to `label2';
1562 TEMP1 is the test for `a == b';
1563 TEMP2 is the conditional jump to `label1';
1564 TEMP3 is the test for `a ~= b'. */
1565 else if (this_is_simplejump
1566 && (temp = prev_active_insn (insn))
1567 && no_labels_between_p (temp, insn)
1568 && condjump_p (temp)
1569 && (temp1 = prev_active_insn (temp))
1570 && no_labels_between_p (temp1, temp)
1571 && GET_CODE (temp1) == INSN
1572 && GET_CODE (PATTERN (temp1)) == SET
1574 && sets_cc0_p (PATTERN (temp1)) == 1
1576 && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
1577 && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
1578 && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
1580 && (temp2 = prev_active_insn (temp1))
1581 && no_labels_between_p (temp2, temp1)
1582 && condjump_p (temp2)
1583 && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
1584 && (temp3 = prev_active_insn (temp2))
1585 && no_labels_between_p (temp3, temp2)
1586 && GET_CODE (PATTERN (temp3)) == SET
1587 && rtx_equal_p (SET_DEST (PATTERN (temp3)),
1588 SET_DEST (PATTERN (temp1)))
1589 && rtx_equal_p (SET_SRC (PATTERN (temp1)),
1590 SET_SRC (PATTERN (temp3)))
1591 && ! inequality_comparisons_p (PATTERN (temp))
1592 && inequality_comparisons_p (PATTERN (temp2)))
1594 rtx fallthrough_label = JUMP_LABEL (temp2);
1596 ++LABEL_NUSES (fallthrough_label);
1597 if (swap_jump (temp2, JUMP_LABEL (insn)))
1603 if (--LABEL_NUSES (fallthrough_label) == 0)
1604 delete_insn (fallthrough_label);
1607 /* Simplify if (...) {... x = 1;} if (x) ...
1609 We recognize this case backwards.
1611 TEMP is the test of `x';
1612 TEMP1 is the assignment to `x' at the end of the
1613 previous statement. */
1614 /* @@ This should call get_condition to find the values being
1615 compared, instead of looking for a COMPARE insn when HAVE_cc0
1616 is not defined. This would allow it to work on the m88k. */
1617 /* @@ This optimization is only safe before cse is run if HAVE_cc0
1618 is not defined and the condition is tested by a separate compare
1619 insn. This is because the code below assumes that the result
1620 of the compare dies in the following branch. */
1622 /* ??? This has to be turned off. The problem is that the
1623 unconditional jump might indirectly end up branching to the
1624 label between TEMP1 and TEMP. We can't detect this, in general,
1625 since it may become a jump to there after further optimizations.
1626 If that jump is done, it will be deleted, so we will retry
1627 this optimization in the next pass, thus an infinite loop.
1629 The present code prevents this by putting the jump after the
1630 label, but this is not logically correct. */
1632 else if (this_is_condjump
1633 /* Safe to skip USE and CLOBBER insns here
1634 since they will not be deleted. */
1635 && (temp = prev_active_insn (insn))
1636 && no_labels_between_p (temp, insn)
1637 && GET_CODE (temp) == INSN
1638 && GET_CODE (PATTERN (temp)) == SET
1640 && sets_cc0_p (PATTERN (temp)) == 1
1641 && GET_CODE (SET_SRC (PATTERN (temp))) == REG
1643 /* Temp must be a compare insn, we can not accept a register
1644 to register move here, since it may not be simply a
1646 && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
1647 && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
1648 && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
1649 && GET_CODE (SET_DEST (PATTERN (temp))) == REG
1650 && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
1652 /* May skip USE or CLOBBER insns here
1653 for checking for opportunity, since we
1654 take care of them later. */
1655 && (temp1 = prev_active_insn (temp))
1656 && GET_CODE (temp1) == INSN
1657 && GET_CODE (PATTERN (temp1)) == SET
1659 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
1661 && (XEXP (SET_SRC (PATTERN (temp)), 0)
1662 == SET_DEST (PATTERN (temp1)))
1664 && CONSTANT_P (SET_SRC (PATTERN (temp1)))
1665 /* If this isn't true, cse will do the job. */
1666 && ! no_labels_between_p (temp1, temp))
1668 /* Get the if_then_else from the condjump. */
1669 rtx choice = SET_SRC (PATTERN (insn));
1670 if (GET_CODE (choice) == IF_THEN_ELSE
1671 && (GET_CODE (XEXP (choice, 0)) == EQ
1672 || GET_CODE (XEXP (choice, 0)) == NE))
1674 int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
1679 /* Get the place that condjump will jump to
1680 if it is reached from here. */
1681 if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
1683 ultimate = XEXP (choice, 1);
1685 ultimate = XEXP (choice, 2);
1686 /* Get it as a CODE_LABEL. */
1687 if (ultimate == pc_rtx)
1688 ultimate = get_label_after (insn);
1690 /* Get the label out of the LABEL_REF. */
1691 ultimate = XEXP (ultimate, 0);
1693 /* Insert the jump immediately before TEMP, specifically
1694 after the label that is between TEMP1 and TEMP. */
1695 last_insn = PREV_INSN (temp);
1697 /* If we would be branching to the next insn, the jump
1698 would immediately be deleted and the re-inserted in
1699 a subsequent pass over the code. So don't do anything
1701 if (next_active_insn (last_insn)
1702 != next_active_insn (ultimate))
1704 emit_barrier_after (last_insn);
1705 p = emit_jump_insn_after (gen_jump (ultimate),
1707 JUMP_LABEL (p) = ultimate;
1708 ++LABEL_NUSES (ultimate);
1709 if (INSN_UID (ultimate) < max_jump_chain
1710 && INSN_CODE (p) < max_jump_chain)
1712 jump_chain[INSN_UID (p)]
1713 = jump_chain[INSN_UID (ultimate)];
1714 jump_chain[INSN_UID (ultimate)] = p;
1722 /* Detect a conditional jump going to the same place
1723 as an immediately following unconditional jump. */
1724 else if (this_is_condjump
1725 && (temp = next_active_insn (insn)) != 0
1726 && simplejump_p (temp)
1727 && (next_active_insn (JUMP_LABEL (insn))
1728 == next_active_insn (JUMP_LABEL (temp))))
1734 /* Detect a conditional jump jumping over an unconditional jump. */
1736 else if ((this_is_condjump || this_is_condjump_in_parallel)
1737 && ! this_is_simplejump
1738 && reallabelprev != 0
1739 && GET_CODE (reallabelprev) == JUMP_INSN
1740 && prev_active_insn (reallabelprev) == insn
1741 && no_labels_between_p (insn, reallabelprev)
1742 && simplejump_p (reallabelprev))
1744 /* When we invert the unconditional jump, we will be
1745 decrementing the usage count of its old label.
1746 Make sure that we don't delete it now because that
1747 might cause the following code to be deleted. */
1748 rtx prev_uses = prev_nonnote_insn (reallabelprev);
1749 rtx prev_label = JUMP_LABEL (insn);
1752 ++LABEL_NUSES (prev_label);
1754 if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
1756 /* It is very likely that if there are USE insns before
1757 this jump, they hold REG_DEAD notes. These REG_DEAD
1758 notes are no longer valid due to this optimization,
1759 and will cause the life-analysis that following passes
1760 (notably delayed-branch scheduling) to think that
1761 these registers are dead when they are not.
1763 To prevent this trouble, we just remove the USE insns
1764 from the insn chain. */
1766 while (prev_uses && GET_CODE (prev_uses) == INSN
1767 && GET_CODE (PATTERN (prev_uses)) == USE)
1769 rtx useless = prev_uses;
1770 prev_uses = prev_nonnote_insn (prev_uses);
1771 delete_insn (useless);
1774 delete_insn (reallabelprev);
1779 /* We can now safely delete the label if it is unreferenced
1780 since the delete_insn above has deleted the BARRIER. */
1781 if (prev_label && --LABEL_NUSES (prev_label) == 0)
1782 delete_insn (prev_label);
1787 /* Detect a jump to a jump. */
1789 nlabel = follow_jumps (JUMP_LABEL (insn));
1790 if (nlabel != JUMP_LABEL (insn)
1791 && redirect_jump (insn, nlabel))
1797 /* Look for if (foo) bar; else break; */
1798 /* The insns look like this:
1799 insn = condjump label1;
1800 ...range1 (some insns)...
1803 ...range2 (some insns)...
1804 jump somewhere unconditionally
1807 rtx label1 = next_label (insn);
1808 rtx range1end = label1 ? prev_active_insn (label1) : 0;
1809 /* Don't do this optimization on the first round, so that
1810 jump-around-a-jump gets simplified before we ask here
1811 whether a jump is unconditional.
1813 Also don't do it when we are called after reload since
1814 it will confuse reorg. */
1816 && (reload_completed ? ! flag_delayed_branch : 1)
1817 /* Make sure INSN is something we can invert. */
1818 && condjump_p (insn)
1820 && JUMP_LABEL (insn) == label1
1821 && LABEL_NUSES (label1) == 1
1822 && GET_CODE (range1end) == JUMP_INSN
1823 && simplejump_p (range1end))
1825 rtx label2 = next_label (label1);
1826 rtx range2end = label2 ? prev_active_insn (label2) : 0;
1827 if (range1end != range2end
1828 && JUMP_LABEL (range1end) == label2
1829 && GET_CODE (range2end) == JUMP_INSN
1830 && GET_CODE (NEXT_INSN (range2end)) == BARRIER
1831 /* Invert the jump condition, so we
1832 still execute the same insns in each case. */
1833 && invert_jump (insn, label1))
1835 rtx range1beg = next_active_insn (insn);
1836 rtx range2beg = next_active_insn (label1);
1837 rtx range1after, range2after;
1838 rtx range1before, range2before;
1841 /* Include in each range any notes before it, to be
1842 sure that we get the line number note if any, even
1843 if there are other notes here. */
1844 while (PREV_INSN (range1beg)
1845 && GET_CODE (PREV_INSN (range1beg)) == NOTE)
1846 range1beg = PREV_INSN (range1beg);
1848 while (PREV_INSN (range2beg)
1849 && GET_CODE (PREV_INSN (range2beg)) == NOTE)
1850 range2beg = PREV_INSN (range2beg);
1852 /* Don't move NOTEs for blocks or loops; shift them
1853 outside the ranges, where they'll stay put. */
1854 range1beg = squeeze_notes (range1beg, range1end);
1855 range2beg = squeeze_notes (range2beg, range2end);
1857 /* Get current surrounds of the 2 ranges. */
1858 range1before = PREV_INSN (range1beg);
1859 range2before = PREV_INSN (range2beg);
1860 range1after = NEXT_INSN (range1end);
1861 range2after = NEXT_INSN (range2end);
1863 /* Splice range2 where range1 was. */
1864 NEXT_INSN (range1before) = range2beg;
1865 PREV_INSN (range2beg) = range1before;
1866 NEXT_INSN (range2end) = range1after;
1867 PREV_INSN (range1after) = range2end;
1868 /* Splice range1 where range2 was. */
1869 NEXT_INSN (range2before) = range1beg;
1870 PREV_INSN (range1beg) = range2before;
1871 NEXT_INSN (range1end) = range2after;
1872 PREV_INSN (range2after) = range1end;
1874 /* Check for a loop end note between the end of
1875 range2, and the next code label. If there is one,
1876 then what we have really seen is
1877 if (foo) break; end_of_loop;
1878 and moved the break sequence outside the loop.
1879 We must move the LOOP_END note to where the
1880 loop really ends now, or we will confuse loop
1881 optimization. Stop if we find a LOOP_BEG note
1882 first, since we don't want to move the LOOP_END
1883 note in that case. */
1884 for (;range2after != label2; range2after = rangenext)
1886 rangenext = NEXT_INSN (range2after);
1887 if (GET_CODE (range2after) == NOTE)
1889 if (NOTE_LINE_NUMBER (range2after)
1890 == NOTE_INSN_LOOP_END)
1892 NEXT_INSN (PREV_INSN (range2after))
1894 PREV_INSN (rangenext)
1895 = PREV_INSN (range2after);
1896 PREV_INSN (range2after)
1897 = PREV_INSN (range1beg);
1898 NEXT_INSN (range2after) = range1beg;
1899 NEXT_INSN (PREV_INSN (range1beg))
1901 PREV_INSN (range1beg) = range2after;
1903 else if (NOTE_LINE_NUMBER (range2after)
1904 == NOTE_INSN_LOOP_BEG)
1914 /* Now that the jump has been tensioned,
1915 try cross jumping: check for identical code
1916 before the jump and before its target label. */
1918 /* First, cross jumping of conditional jumps: */
1920 if (cross_jump && condjump_p (insn))
1922 rtx newjpos, newlpos;
1923 rtx x = prev_real_insn (JUMP_LABEL (insn));
1925 /* A conditional jump may be crossjumped
1926 only if the place it jumps to follows
1927 an opposing jump that comes back here. */
1929 if (x != 0 && ! jump_back_p (x, insn))
1930 /* We have no opposing jump;
1931 cannot cross jump this insn. */
1935 /* TARGET is nonzero if it is ok to cross jump
1936 to code before TARGET. If so, see if matches. */
1938 find_cross_jump (insn, x, 2,
1939 &newjpos, &newlpos);
1943 do_cross_jump (insn, newjpos, newlpos);
1944 /* Make the old conditional jump
1945 into an unconditional one. */
1946 SET_SRC (PATTERN (insn))
1947 = gen_rtx (LABEL_REF, VOIDmode, JUMP_LABEL (insn));
1948 INSN_CODE (insn) = -1;
1949 emit_barrier_after (insn);
1950 /* Add to jump_chain unless this is a new label
1951 whose UID is too large. */
1952 if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
1954 jump_chain[INSN_UID (insn)]
1955 = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1956 jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
1963 /* Cross jumping of unconditional jumps:
1964 a few differences. */
1966 if (cross_jump && simplejump_p (insn))
1968 rtx newjpos, newlpos;
1973 /* TARGET is nonzero if it is ok to cross jump
1974 to code before TARGET. If so, see if matches. */
1975 find_cross_jump (insn, JUMP_LABEL (insn), 1,
1976 &newjpos, &newlpos);
1978 /* If cannot cross jump to code before the label,
1979 see if we can cross jump to another jump to
1981 /* Try each other jump to this label. */
1982 if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
1983 for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
1984 target != 0 && newjpos == 0;
1985 target = jump_chain[INSN_UID (target)])
1987 && JUMP_LABEL (target) == JUMP_LABEL (insn)
1988 /* Ignore TARGET if it's deleted. */
1989 && ! INSN_DELETED_P (target))
1990 find_cross_jump (insn, target, 2,
1991 &newjpos, &newlpos);
1995 do_cross_jump (insn, newjpos, newlpos);
2001 /* This code was dead in the previous jump.c! */
2002 if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
2004 /* Return insns all "jump to the same place"
2005 so we can cross-jump between any two of them. */
2007 rtx newjpos, newlpos, target;
2011 /* If cannot cross jump to code before the label,
2012 see if we can cross jump to another jump to
2014 /* Try each other jump to this label. */
2015 for (target = jump_chain[0];
2016 target != 0 && newjpos == 0;
2017 target = jump_chain[INSN_UID (target)])
2019 && ! INSN_DELETED_P (target)
2020 && GET_CODE (PATTERN (target)) == RETURN)
2021 find_cross_jump (insn, target, 2,
2022 &newjpos, &newlpos);
2026 do_cross_jump (insn, newjpos, newlpos);
2037 /* Delete extraneous line number notes.
2038 Note that two consecutive notes for different lines are not really
2039 extraneous. There should be some indication where that line belonged,
2040 even if it became empty. */
2045 for (insn = f; insn; insn = NEXT_INSN (insn))
2046 if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
2048 /* Delete this note if it is identical to previous note. */
2050 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
2051 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
2064 /* If we fall through to the epilogue, see if we can insert a RETURN insn
2065 in front of it. If the machine allows it at this point (we might be
2066 after reload for a leaf routine), it will improve optimization for it
2067 to be there. We do this both here and at the start of this pass since
2068 the RETURN might have been deleted by some of our optimizations. */
2069 insn = get_last_insn ();
2070 while (insn && GET_CODE (insn) == NOTE)
2071 insn = PREV_INSN (insn);
2073 if (insn && GET_CODE (insn) != BARRIER)
2075 emit_jump_insn (gen_return ());
2081 /* See if there is still a NOTE_INSN_FUNCTION_END in this function.
2082 If so, delete it, and record that this function can drop off the end. */
2088 /* One label can follow the end-note: the return label. */
2089 && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
2090 /* Ordinary insns can follow it if returning a structure. */
2091 || GET_CODE (insn) == INSN
2092 /* If machine uses explicit RETURN insns, no epilogue,
2093 then one of them follows the note. */
2094 || (GET_CODE (insn) == JUMP_INSN
2095 && GET_CODE (PATTERN (insn)) == RETURN)
2096 /* Other kinds of notes can follow also. */
2097 || (GET_CODE (insn) == NOTE
2098 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)))
2099 insn = PREV_INSN (insn);
2102 /* Report if control can fall through at the end of the function. */
2103 if (insn && GET_CODE (insn) == NOTE
2104 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
2110 /* Show JUMP_CHAIN no longer valid. */
2114 /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
2115 jump. Assume that this unconditional jump is to the exit test code. If
2116 the code is sufficiently simple, make a copy of it before INSN,
2117 followed by a jump to the exit of the loop. Then delete the unconditional
2120 Note that it is possible we can get confused here if the jump immediately
2121 after the loop start branches outside the loop but within an outer loop.
2122 If we are near the exit of that loop, we will copy its exit test. This
2123 will not generate incorrect code, but could suppress some optimizations.
2124 However, such cases are degenerate loops anyway.
2126 Return 1 if we made the change, else 0.
2128 This is only safe immediately after a regscan pass because it uses the
2129 values of regno_first_uid and regno_last_uid. */
2132 duplicate_loop_exit_test (loop_start)
2135 rtx insn, set, reg, p, link;
2138 rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
2140 int max_reg = max_reg_num ();
2143 /* Scan the exit code. We do not perform this optimization if any insn:
2147 has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
2148 is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
2149 is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
2152 Also, don't do this if the exit code is more than 20 insns. */
2154 for (insn = exitcode;
2156 && ! (GET_CODE (insn) == NOTE
2157 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
2158 insn = NEXT_INSN (insn))
2160 switch (GET_CODE (insn))
2166 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2167 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2168 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
2173 if (++num_insns > 20
2174 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
2175 || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2181 /* Unless INSN is zero, we can do the optimization. */
2187 /* See if any insn sets a register only used in the loop exit code and
2188 not a user variable. If so, replace it with a new register. */
2189 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2190 if (GET_CODE (insn) == INSN
2191 && (set = single_set (insn)) != 0
2192 && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
2193 || (GET_CODE (reg) == SUBREG
2194 && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
2195 && REGNO (reg) >= FIRST_PSEUDO_REGISTER
2196 && regno_first_uid[REGNO (reg)] == INSN_UID (insn))
2198 for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
2199 if (regno_last_uid[REGNO (reg)] == INSN_UID (p))
2204 /* We can do the replacement. Allocate reg_map if this is the
2205 first replacement we found. */
2208 reg_map = (rtx *) alloca (max_reg * sizeof (rtx));
2209 bzero ((char *) reg_map, max_reg * sizeof (rtx));
2212 REG_LOOP_TEST_P (reg) = 1;
2214 reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
2218 /* Now copy each insn. */
2219 for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
2220 switch (GET_CODE (insn))
2223 copy = emit_barrier_before (loop_start);
2226 /* Only copy line-number notes. */
2227 if (NOTE_LINE_NUMBER (insn) >= 0)
2229 copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
2230 NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
2235 copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2237 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2239 mark_jump_label (PATTERN (copy), copy, 0);
2241 /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
2243 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2244 if (REG_NOTE_KIND (link) != REG_LABEL)
2246 = copy_rtx (gen_rtx (EXPR_LIST, REG_NOTE_KIND (link),
2247 XEXP (link, 0), REG_NOTES (copy)));
2248 if (reg_map && REG_NOTES (copy))
2249 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2253 copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start);
2255 replace_regs (PATTERN (copy), reg_map, max_reg, 1);
2256 mark_jump_label (PATTERN (copy), copy, 0);
2257 if (REG_NOTES (insn))
2259 REG_NOTES (copy) = copy_rtx (REG_NOTES (insn));
2261 replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
2264 /* If this is a simple jump, add it to the jump chain. */
2266 if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
2267 && simplejump_p (copy))
2269 jump_chain[INSN_UID (copy)]
2270 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2271 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2279 /* Now clean up by emitting a jump to the end label and deleting the jump
2280 at the start of the loop. */
2281 if (! copy || GET_CODE (copy) != BARRIER)
2283 copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
2285 mark_jump_label (PATTERN (copy), copy, 0);
2286 if (INSN_UID (copy) < max_jump_chain
2287 && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
2289 jump_chain[INSN_UID (copy)]
2290 = jump_chain[INSN_UID (JUMP_LABEL (copy))];
2291 jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
2293 emit_barrier_before (loop_start);
2296 /* Mark the exit code as the virtual top of the converted loop. */
2297 emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
2299 delete_insn (next_nonnote_insn (loop_start));
2304 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
2305 loop-end notes between START and END out before START. Assume that
2306 END is not such a note. START may be such a note. Returns the value
2307 of the new starting insn, which may be different if the original start
2311 squeeze_notes (start, end)
2317 for (insn = start; insn != end; insn = next)
2319 next = NEXT_INSN (insn);
2320 if (GET_CODE (insn) == NOTE
2321 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
2322 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
2323 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
2324 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
2325 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
2326 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
2332 rtx prev = PREV_INSN (insn);
2333 PREV_INSN (insn) = PREV_INSN (start);
2334 NEXT_INSN (insn) = start;
2335 NEXT_INSN (PREV_INSN (insn)) = insn;
2336 PREV_INSN (NEXT_INSN (insn)) = insn;
2337 NEXT_INSN (prev) = next;
2338 PREV_INSN (next) = prev;
2346 /* Compare the instructions before insn E1 with those before E2
2347 to find an opportunity for cross jumping.
2348 (This means detecting identical sequences of insns followed by
2349 jumps to the same place, or followed by a label and a jump
2350 to that label, and replacing one with a jump to the other.)
2352 Assume E1 is a jump that jumps to label E2
2353 (that is not always true but it might as well be).
2354 Find the longest possible equivalent sequences
2355 and store the first insns of those sequences into *F1 and *F2.
2356 Store zero there if no equivalent preceding instructions are found.
2358 We give up if we find a label in stream 1.
2359 Actually we could transfer that label into stream 2. */
2362 find_cross_jump (e1, e2, minimum, f1, f2)
2367 register rtx i1 = e1, i2 = e2;
2368 register rtx p1, p2;
2371 rtx last1 = 0, last2 = 0;
2372 rtx afterlast1 = 0, afterlast2 = 0;
2380 i1 = prev_nonnote_insn (i1);
2382 i2 = PREV_INSN (i2);
2383 while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
2384 i2 = PREV_INSN (i2);
2389 /* Don't allow the range of insns preceding E1 or E2
2390 to include the other (E2 or E1). */
2391 if (i2 == e1 || i1 == e2)
2394 /* If we will get to this code by jumping, those jumps will be
2395 tensioned to go directly to the new label (before I2),
2396 so this cross-jumping won't cost extra. So reduce the minimum. */
2397 if (GET_CODE (i1) == CODE_LABEL)
2403 if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
2409 /* If this is a CALL_INSN, compare register usage information.
2410 If we don't check this on stack register machines, the two
2411 CALL_INSNs might be merged leaving reg-stack.c with mismatching
2412 numbers of stack registers in the same basic block.
2413 If we don't check this on machines with delay slots, a delay slot may
2414 be filled that clobbers a parameter expected by the subroutine.
2416 ??? We take the simple route for now and assume that if they're
2417 equal, they were constructed identically. */
2419 if (GET_CODE (i1) == CALL_INSN
2420 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
2421 CALL_INSN_FUNCTION_USAGE (i2)))
2425 /* If cross_jump_death_matters is not 0, the insn's mode
2426 indicates whether or not the insn contains any stack-like
2429 if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode)
2431 /* If register stack conversion has already been done, then
2432 death notes must also be compared before it is certain that
2433 the two instruction streams match. */
2436 HARD_REG_SET i1_regset, i2_regset;
2438 CLEAR_HARD_REG_SET (i1_regset);
2439 CLEAR_HARD_REG_SET (i2_regset);
2441 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
2442 if (REG_NOTE_KIND (note) == REG_DEAD
2443 && STACK_REG_P (XEXP (note, 0)))
2444 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
2446 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
2447 if (REG_NOTE_KIND (note) == REG_DEAD
2448 && STACK_REG_P (XEXP (note, 0)))
2449 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
2451 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
2460 if (lose || GET_CODE (p1) != GET_CODE (p2)
2461 || ! rtx_renumbered_equal_p (p1, p2))
2463 /* The following code helps take care of G++ cleanups. */
2467 if (!lose && GET_CODE (p1) == GET_CODE (p2)
2468 && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
2469 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
2470 && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
2471 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
2472 /* If the equivalences are not to a constant, they may
2473 reference pseudos that no longer exist, so we can't
2475 && CONSTANT_P (XEXP (equiv1, 0))
2476 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
2478 rtx s1 = single_set (i1);
2479 rtx s2 = single_set (i2);
2480 if (s1 != 0 && s2 != 0
2481 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
2483 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
2484 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
2485 if (! rtx_renumbered_equal_p (p1, p2))
2487 else if (apply_change_group ())
2492 /* Insns fail to match; cross jumping is limited to the following
2496 /* Don't allow the insn after a compare to be shared by
2497 cross-jumping unless the compare is also shared.
2498 Here, if either of these non-matching insns is a compare,
2499 exclude the following insn from possible cross-jumping. */
2500 if (sets_cc0_p (p1) || sets_cc0_p (p2))
2501 last1 = afterlast1, last2 = afterlast2, ++minimum;
2504 /* If cross-jumping here will feed a jump-around-jump
2505 optimization, this jump won't cost extra, so reduce
2507 if (GET_CODE (i1) == JUMP_INSN
2509 && prev_real_insn (JUMP_LABEL (i1)) == e1)
2515 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
2517 /* Ok, this insn is potentially includable in a cross-jump here. */
2518 afterlast1 = last1, afterlast2 = last2;
2519 last1 = i1, last2 = i2, --minimum;
2523 if (minimum <= 0 && last1 != 0 && last1 != e1)
2524 *f1 = last1, *f2 = last2;
2528 do_cross_jump (insn, newjpos, newlpos)
2529 rtx insn, newjpos, newlpos;
2531 /* Find an existing label at this point
2532 or make a new one if there is none. */
2533 register rtx label = get_label_before (newlpos);
2535 /* Make the same jump insn jump to the new point. */
2536 if (GET_CODE (PATTERN (insn)) == RETURN)
2538 /* Remove from jump chain of returns. */
2539 delete_from_jump_chain (insn);
2540 /* Change the insn. */
2541 PATTERN (insn) = gen_jump (label);
2542 INSN_CODE (insn) = -1;
2543 JUMP_LABEL (insn) = label;
2544 LABEL_NUSES (label)++;
2545 /* Add to new the jump chain. */
2546 if (INSN_UID (label) < max_jump_chain
2547 && INSN_UID (insn) < max_jump_chain)
2549 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)];
2550 jump_chain[INSN_UID (label)] = insn;
2554 redirect_jump (insn, label);
2556 /* Delete the matching insns before the jump. Also, remove any REG_EQUAL
2557 or REG_EQUIV note in the NEWLPOS stream that isn't also present in
2558 the NEWJPOS stream. */
2560 while (newjpos != insn)
2564 for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1))
2565 if ((REG_NOTE_KIND (lnote) == REG_EQUAL
2566 || REG_NOTE_KIND (lnote) == REG_EQUIV)
2567 && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0))
2568 && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0)))
2569 remove_note (newlpos, lnote);
2571 delete_insn (newjpos);
2572 newjpos = next_real_insn (newjpos);
2573 newlpos = next_real_insn (newlpos);
2577 /* Return the label before INSN, or put a new label there. */
2580 get_label_before (insn)
2585 /* Find an existing label at this point
2586 or make a new one if there is none. */
2587 label = prev_nonnote_insn (insn);
2589 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2591 rtx prev = PREV_INSN (insn);
2593 label = gen_label_rtx ();
2594 emit_label_after (label, prev);
2595 LABEL_NUSES (label) = 0;
2600 /* Return the label after INSN, or put a new label there. */
2603 get_label_after (insn)
2608 /* Find an existing label at this point
2609 or make a new one if there is none. */
2610 label = next_nonnote_insn (insn);
2612 if (label == 0 || GET_CODE (label) != CODE_LABEL)
2614 label = gen_label_rtx ();
2615 emit_label_after (label, insn);
2616 LABEL_NUSES (label) = 0;
2621 /* Return 1 if INSN is a jump that jumps to right after TARGET
2622 only on the condition that TARGET itself would drop through.
2623 Assumes that TARGET is a conditional jump. */
2626 jump_back_p (insn, target)
2630 enum rtx_code codei, codet;
2632 if (simplejump_p (insn) || ! condjump_p (insn)
2633 || simplejump_p (target)
2634 || target != prev_real_insn (JUMP_LABEL (insn)))
2637 cinsn = XEXP (SET_SRC (PATTERN (insn)), 0);
2638 ctarget = XEXP (SET_SRC (PATTERN (target)), 0);
2640 codei = GET_CODE (cinsn);
2641 codet = GET_CODE (ctarget);
2643 if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx)
2645 if (! can_reverse_comparison_p (cinsn, insn))
2647 codei = reverse_condition (codei);
2650 if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx)
2652 if (! can_reverse_comparison_p (ctarget, target))
2654 codet = reverse_condition (codet);
2657 return (codei == codet
2658 && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0))
2659 && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1)));
2662 /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN,
2663 return non-zero if it is safe to reverse this comparison. It is if our
2664 floating-point is not IEEE, if this is an NE or EQ comparison, or if
2665 this is known to be an integer comparison. */
2668 can_reverse_comparison_p (comparison, insn)
2674 /* If this is not actually a comparison, we can't reverse it. */
2675 if (GET_RTX_CLASS (GET_CODE (comparison)) != '<')
2678 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
2679 /* If this is an NE comparison, it is safe to reverse it to an EQ
2680 comparison and vice versa, even for floating point. If no operands
2681 are NaNs, the reversal is valid. If some operand is a NaN, EQ is
2682 always false and NE is always true, so the reversal is also valid. */
2684 || GET_CODE (comparison) == NE
2685 || GET_CODE (comparison) == EQ)
2688 arg0 = XEXP (comparison, 0);
2690 /* Make sure ARG0 is one of the actual objects being compared. If we
2691 can't do this, we can't be sure the comparison can be reversed.
2693 Handle cc0 and a MODE_CC register. */
2694 if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC)
2700 rtx prev = prev_nonnote_insn (insn);
2701 rtx set = single_set (prev);
2703 if (set == 0 || SET_DEST (set) != arg0)
2706 arg0 = SET_SRC (set);
2708 if (GET_CODE (arg0) == COMPARE)
2709 arg0 = XEXP (arg0, 0);
2712 /* We can reverse this if ARG0 is a CONST_INT or if its mode is
2713 not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */
2714 return (GET_CODE (arg0) == CONST_INT
2715 || (GET_MODE (arg0) != VOIDmode
2716 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC
2717 && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT));
2720 /* Given an rtx-code for a comparison, return the code
2721 for the negated comparison.
2722 WATCH OUT! reverse_condition is not safe to use on a jump
2723 that might be acting on the results of an IEEE floating point comparison,
2724 because of the special treatment of non-signaling nans in comparisons.
2725 Use can_reverse_comparison_p to be sure. */
2728 reverse_condition (code)
2769 /* Similar, but return the code when two operands of a comparison are swapped.
2770 This IS safe for IEEE floating-point. */
2773 swap_condition (code)
2812 /* Given a comparison CODE, return the corresponding unsigned comparison.
2813 If CODE is an equality comparison or already an unsigned comparison,
2814 CODE is returned. */
2817 unsigned_condition (code)
2847 /* Similarly, return the signed version of a comparison. */
2850 signed_condition (code)
2880 /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the
2881 truth of CODE1 implies the truth of CODE2. */
2884 comparison_dominates_p (code1, code2)
2885 enum rtx_code code1, code2;
2893 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU)
2898 if (code2 == LE || code2 == NE)
2903 if (code2 == GE || code2 == NE)
2908 if (code2 == LEU || code2 == NE)
2913 if (code2 == GEU || code2 == NE)
2921 /* Return 1 if INSN is an unconditional jump and nothing else. */
2927 return (GET_CODE (insn) == JUMP_INSN
2928 && GET_CODE (PATTERN (insn)) == SET
2929 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
2930 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
2933 /* Return nonzero if INSN is a (possibly) conditional jump
2934 and nothing more. */
2940 register rtx x = PATTERN (insn);
2941 if (GET_CODE (x) != SET)
2943 if (GET_CODE (SET_DEST (x)) != PC)
2945 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2947 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2949 if (XEXP (SET_SRC (x), 2) == pc_rtx
2950 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2951 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2953 if (XEXP (SET_SRC (x), 1) == pc_rtx
2954 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2955 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2960 /* Return nonzero if INSN is a (possibly) conditional jump
2961 and nothing more. */
2964 condjump_in_parallel_p (insn)
2967 register rtx x = PATTERN (insn);
2969 if (GET_CODE (x) != PARALLEL)
2972 x = XVECEXP (x, 0, 0);
2974 if (GET_CODE (x) != SET)
2976 if (GET_CODE (SET_DEST (x)) != PC)
2978 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
2980 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
2982 if (XEXP (SET_SRC (x), 2) == pc_rtx
2983 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
2984 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
2986 if (XEXP (SET_SRC (x), 1) == pc_rtx
2987 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
2988 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
2993 /* Return 1 if X is an RTX that does nothing but set the condition codes
2994 and CLOBBER or USE registers.
2995 Return -1 if X does explicitly set the condition codes,
2996 but also does other things. */
3003 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
3005 if (GET_CODE (x) == PARALLEL)
3009 int other_things = 0;
3010 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3012 if (GET_CODE (XVECEXP (x, 0, i)) == SET
3013 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
3015 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
3018 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
3026 /* Follow any unconditional jump at LABEL;
3027 return the ultimate label reached by any such chain of jumps.
3028 If LABEL is not followed by a jump, return LABEL.
3029 If the chain loops or we can't find end, return LABEL,
3030 since that tells caller to avoid changing the insn.
3032 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
3033 a USE or CLOBBER. */
3036 follow_jumps (label)
3041 register rtx value = label;
3046 && (insn = next_active_insn (value)) != 0
3047 && GET_CODE (insn) == JUMP_INSN
3048 && (JUMP_LABEL (insn) != 0 || GET_CODE (PATTERN (insn)) == RETURN)
3049 && (next = NEXT_INSN (insn))
3050 && GET_CODE (next) == BARRIER);
3053 /* Don't chain through the insn that jumps into a loop
3054 from outside the loop,
3055 since that would create multiple loop entry jumps
3056 and prevent loop optimization. */
3058 if (!reload_completed)
3059 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
3060 if (GET_CODE (tem) == NOTE
3061 && NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG)
3064 /* If we have found a cycle, make the insn jump to itself. */
3065 if (JUMP_LABEL (insn) == label)
3068 tem = next_active_insn (JUMP_LABEL (insn));
3069 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
3070 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
3073 value = JUMP_LABEL (insn);
3080 /* Assuming that field IDX of X is a vector of label_refs,
3081 replace each of them by the ultimate label reached by it.
3082 Return nonzero if a change is made.
3083 If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */
3086 tension_vector_labels (x, idx)
3092 for (i = XVECLEN (x, idx) - 1; i >= 0; i--)
3094 register rtx olabel = XEXP (XVECEXP (x, idx, i), 0);
3095 register rtx nlabel = follow_jumps (olabel);
3096 if (nlabel && nlabel != olabel)
3098 XEXP (XVECEXP (x, idx, i), 0) = nlabel;
3099 ++LABEL_NUSES (nlabel);
3100 if (--LABEL_NUSES (olabel) == 0)
3101 delete_insn (olabel);
3108 /* Find all CODE_LABELs referred to in X, and increment their use counts.
3109 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
3110 in INSN, then store one of them in JUMP_LABEL (INSN).
3111 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
3112 referenced in INSN, add a REG_LABEL note containing that label to INSN.
3113 Also, when there are consecutive labels, canonicalize on the last of them.
3115 Note that two labels separated by a loop-beginning note
3116 must be kept distinct if we have not yet done loop-optimization,
3117 because the gap between them is where loop-optimize
3118 will want to move invariant code to. CROSS_JUMP tells us
3119 that loop-optimization is done with.
3121 Once reload has completed (CROSS_JUMP non-zero), we need not consider
3122 two labels distinct if they are separated by only USE or CLOBBER insns. */
3125 mark_jump_label (x, insn, cross_jump)
3130 register RTX_CODE code = GET_CODE (x);
3148 /* If this is a constant-pool reference, see if it is a label. */
3149 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3150 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3151 mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump);
3156 rtx label = XEXP (x, 0);
3161 if (GET_CODE (label) != CODE_LABEL)
3164 /* Ignore references to labels of containing functions. */
3165 if (LABEL_REF_NONLOCAL_P (x))
3168 /* If there are other labels following this one,
3169 replace it with the last of the consecutive labels. */
3170 for (next = NEXT_INSN (label); next; next = NEXT_INSN (next))
3172 if (GET_CODE (next) == CODE_LABEL)
3174 else if (cross_jump && GET_CODE (next) == INSN
3175 && (GET_CODE (PATTERN (next)) == USE
3176 || GET_CODE (PATTERN (next)) == CLOBBER))
3178 else if (GET_CODE (next) != NOTE)
3180 else if (! cross_jump
3181 && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG
3182 || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END))
3186 XEXP (x, 0) = label;
3187 ++LABEL_NUSES (label);
3191 if (GET_CODE (insn) == JUMP_INSN)
3192 JUMP_LABEL (insn) = label;
3194 /* If we've changed OLABEL and we had a REG_LABEL note
3195 for it, update it as well. */
3196 else if (label != olabel
3197 && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0)
3198 XEXP (note, 0) = label;
3200 /* Otherwise, add a REG_LABEL note for LABEL unless there already
3202 else if (! find_reg_note (insn, REG_LABEL, label))
3204 rtx next = next_real_insn (label);
3205 /* Don't record labels that refer to dispatch tables.
3206 This is not necessary, since the tablejump
3207 references the same label.
3208 And if we did record them, flow.c would make worse code. */
3210 || ! (GET_CODE (next) == JUMP_INSN
3211 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3212 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC)))
3213 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, label,
3220 /* Do walk the labels in a vector, but not the first operand of an
3221 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
3225 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
3227 for (i = 0; i < XVECLEN (x, eltnum); i++)
3228 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump);
3233 fmt = GET_RTX_FORMAT (code);
3234 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3237 mark_jump_label (XEXP (x, i), insn, cross_jump);
3238 else if (fmt[i] == 'E')
3241 for (j = 0; j < XVECLEN (x, i); j++)
3242 mark_jump_label (XVECEXP (x, i, j), insn, cross_jump);
3247 /* If all INSN does is set the pc, delete it,
3248 and delete the insn that set the condition codes for it
3249 if that's what the previous thing was. */
3255 register rtx set = single_set (insn);
3257 if (set && GET_CODE (SET_DEST (set)) == PC)
3258 delete_computation (insn);
3261 /* Delete INSN and recursively delete insns that compute values used only
3262 by INSN. This uses the REG_DEAD notes computed during flow analysis.
3263 If we are running before flow.c, we need do nothing since flow.c will
3264 delete dead code. We also can't know if the registers being used are
3265 dead or not at this point.
3267 Otherwise, look at all our REG_DEAD notes. If a previous insn does
3268 nothing other than set a register that dies in this insn, we can delete
3271 On machines with CC0, if CC0 is used in this insn, we may be able to
3272 delete the insn that set it. */
3275 delete_computation (insn)
3281 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
3283 rtx prev = prev_nonnote_insn (insn);
3284 /* We assume that at this stage
3285 CC's are always set explicitly
3286 and always immediately before the jump that
3287 will use them. So if the previous insn
3288 exists to set the CC's, delete it
3289 (unless it performs auto-increments, etc.). */
3290 if (prev && GET_CODE (prev) == INSN
3291 && sets_cc0_p (PATTERN (prev)))
3293 if (sets_cc0_p (PATTERN (prev)) > 0
3294 && !FIND_REG_INC_NOTE (prev, NULL_RTX))
3295 delete_computation (prev);
3297 /* Otherwise, show that cc0 won't be used. */
3298 REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
3299 cc0_rtx, REG_NOTES (prev));
3304 for (note = REG_NOTES (insn); note; note = next)
3308 next = XEXP (note, 1);
3310 if (REG_NOTE_KIND (note) != REG_DEAD
3311 /* Verify that the REG_NOTE is legitimate. */
3312 || GET_CODE (XEXP (note, 0)) != REG)
3315 for (our_prev = prev_nonnote_insn (insn);
3316 our_prev && GET_CODE (our_prev) == INSN;
3317 our_prev = prev_nonnote_insn (our_prev))
3319 /* If we reach a SEQUENCE, it is too complex to try to
3320 do anything with it, so give up. */
3321 if (GET_CODE (PATTERN (our_prev)) == SEQUENCE)
3324 if (GET_CODE (PATTERN (our_prev)) == USE
3325 && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN)
3326 /* reorg creates USEs that look like this. We leave them
3327 alone because reorg needs them for its own purposes. */
3330 if (reg_set_p (XEXP (note, 0), PATTERN (our_prev)))
3332 if (FIND_REG_INC_NOTE (our_prev, NULL_RTX))
3335 if (GET_CODE (PATTERN (our_prev)) == PARALLEL)
3337 /* If we find a SET of something else, we can't
3342 for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++)
3344 rtx part = XVECEXP (PATTERN (our_prev), 0, i);
3346 if (GET_CODE (part) == SET
3347 && SET_DEST (part) != XEXP (note, 0))
3351 if (i == XVECLEN (PATTERN (our_prev), 0))
3352 delete_computation (our_prev);
3354 else if (GET_CODE (PATTERN (our_prev)) == SET
3355 && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
3356 delete_computation (our_prev);
3361 /* If OUR_PREV references the register that dies here, it is an
3362 additional use. Hence any prior SET isn't dead. However, this
3363 insn becomes the new place for the REG_DEAD note. */
3364 if (reg_overlap_mentioned_p (XEXP (note, 0),
3365 PATTERN (our_prev)))
3367 XEXP (note, 1) = REG_NOTES (our_prev);
3368 REG_NOTES (our_prev) = note;
3377 /* Delete insn INSN from the chain of insns and update label ref counts.
3378 May delete some following insns as a consequence; may even delete
3379 a label elsewhere and insns that follow it.
3381 Returns the first insn after INSN that was not deleted. */
3387 register rtx next = NEXT_INSN (insn);
3388 register rtx prev = PREV_INSN (insn);
3389 register int was_code_label = (GET_CODE (insn) == CODE_LABEL);
3390 register int dont_really_delete = 0;
3392 while (next && INSN_DELETED_P (next))
3393 next = NEXT_INSN (next);
3395 /* This insn is already deleted => return first following nondeleted. */
3396 if (INSN_DELETED_P (insn))
3399 /* Don't delete user-declared labels. Convert them to special NOTEs
3401 if (was_code_label && LABEL_NAME (insn) != 0
3402 && optimize && ! dont_really_delete)
3404 PUT_CODE (insn, NOTE);
3405 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
3406 NOTE_SOURCE_FILE (insn) = 0;
3407 dont_really_delete = 1;
3410 /* Mark this insn as deleted. */
3411 INSN_DELETED_P (insn) = 1;
3413 /* If this is an unconditional jump, delete it from the jump chain. */
3414 if (simplejump_p (insn))
3415 delete_from_jump_chain (insn);
3417 /* If instruction is followed by a barrier,
3418 delete the barrier too. */
3420 if (next != 0 && GET_CODE (next) == BARRIER)
3422 INSN_DELETED_P (next) = 1;
3423 next = NEXT_INSN (next);
3426 /* Patch out INSN (and the barrier if any) */
3428 if (optimize && ! dont_really_delete)
3432 NEXT_INSN (prev) = next;
3433 if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE)
3434 NEXT_INSN (XVECEXP (PATTERN (prev), 0,
3435 XVECLEN (PATTERN (prev), 0) - 1)) = next;
3440 PREV_INSN (next) = prev;
3441 if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE)
3442 PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev;
3445 if (prev && NEXT_INSN (prev) == 0)
3446 set_last_insn (prev);
3449 /* If deleting a jump, decrement the count of the label,
3450 and delete the label if it is now unused. */
3452 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
3453 if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0)
3455 /* This can delete NEXT or PREV,
3456 either directly if NEXT is JUMP_LABEL (INSN),
3457 or indirectly through more levels of jumps. */
3458 delete_insn (JUMP_LABEL (insn));
3459 /* I feel a little doubtful about this loop,
3460 but I see no clean and sure alternative way
3461 to find the first insn after INSN that is not now deleted.
3462 I hope this works. */
3463 while (next && INSN_DELETED_P (next))
3464 next = NEXT_INSN (next);
3468 /* Likewise if we're deleting a dispatch table. */
3470 if (GET_CODE (insn) == JUMP_INSN
3471 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
3472 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
3474 rtx pat = PATTERN (insn);
3475 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3476 int len = XVECLEN (pat, diff_vec_p);
3478 for (i = 0; i < len; i++)
3479 if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
3480 delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
3481 while (next && INSN_DELETED_P (next))
3482 next = NEXT_INSN (next);
3486 while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE))
3487 prev = PREV_INSN (prev);
3489 /* If INSN was a label and a dispatch table follows it,
3490 delete the dispatch table. The tablejump must have gone already.
3491 It isn't useful to fall through into a table. */
3494 && NEXT_INSN (insn) != 0
3495 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
3496 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
3497 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
3498 next = delete_insn (NEXT_INSN (insn));
3500 /* If INSN was a label, delete insns following it if now unreachable. */
3502 if (was_code_label && prev && GET_CODE (prev) == BARRIER)
3504 register RTX_CODE code;
3506 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i'
3508 || (code == CODE_LABEL && INSN_DELETED_P (next))))
3511 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
3512 next = NEXT_INSN (next);
3513 /* Keep going past other deleted labels to delete what follows. */
3514 else if (code == CODE_LABEL && INSN_DELETED_P (next))
3515 next = NEXT_INSN (next);
3517 /* Note: if this deletes a jump, it can cause more
3518 deletion of unreachable code, after a different label.
3519 As long as the value from this recursive call is correct,
3520 this invocation functions correctly. */
3521 next = delete_insn (next);
3528 /* Advance from INSN till reaching something not deleted
3529 then return that. May return INSN itself. */
3532 next_nondeleted_insn (insn)
3535 while (INSN_DELETED_P (insn))
3536 insn = NEXT_INSN (insn);
3540 /* Delete a range of insns from FROM to TO, inclusive.
3541 This is for the sake of peephole optimization, so assume
3542 that whatever these insns do will still be done by a new
3543 peephole insn that will replace them. */
3546 delete_for_peephole (from, to)
3547 register rtx from, to;
3549 register rtx insn = from;
3553 register rtx next = NEXT_INSN (insn);
3554 register rtx prev = PREV_INSN (insn);
3556 if (GET_CODE (insn) != NOTE)
3558 INSN_DELETED_P (insn) = 1;
3560 /* Patch this insn out of the chain. */
3561 /* We don't do this all at once, because we
3562 must preserve all NOTEs. */
3564 NEXT_INSN (prev) = next;
3567 PREV_INSN (next) = prev;
3575 /* Note that if TO is an unconditional jump
3576 we *do not* delete the BARRIER that follows,
3577 since the peephole that replaces this sequence
3578 is also an unconditional jump in that case. */
3581 /* Invert the condition of the jump JUMP, and make it jump
3582 to label NLABEL instead of where it jumps now. */
3585 invert_jump (jump, nlabel)
3588 /* We have to either invert the condition and change the label or
3589 do neither. Either operation could fail. We first try to invert
3590 the jump. If that succeeds, we try changing the label. If that fails,
3591 we invert the jump back to what it was. */
3593 if (! invert_exp (PATTERN (jump), jump))
3596 if (redirect_jump (jump, nlabel))
3599 if (! invert_exp (PATTERN (jump), jump))
3600 /* This should just be putting it back the way it was. */
3606 /* Invert the jump condition of rtx X contained in jump insn, INSN.
3608 Return 1 if we can do so, 0 if we cannot find a way to do so that
3609 matches a pattern. */
3612 invert_exp (x, insn)
3616 register RTX_CODE code;
3620 code = GET_CODE (x);
3622 if (code == IF_THEN_ELSE)
3624 register rtx comp = XEXP (x, 0);
3627 /* We can do this in two ways: The preferable way, which can only
3628 be done if this is not an integer comparison, is to reverse
3629 the comparison code. Otherwise, swap the THEN-part and ELSE-part
3630 of the IF_THEN_ELSE. If we can't do either, fail. */
3632 if (can_reverse_comparison_p (comp, insn)
3633 && validate_change (insn, &XEXP (x, 0),
3634 gen_rtx (reverse_condition (GET_CODE (comp)),
3635 GET_MODE (comp), XEXP (comp, 0),
3636 XEXP (comp, 1)), 0))
3640 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
3641 validate_change (insn, &XEXP (x, 2), tem, 1);
3642 return apply_change_group ();
3645 fmt = GET_RTX_FORMAT (code);
3646 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3649 if (! invert_exp (XEXP (x, i), insn))
3654 for (j = 0; j < XVECLEN (x, i); j++)
3655 if (!invert_exp (XVECEXP (x, i, j), insn))
3663 /* Make jump JUMP jump to label NLABEL instead of where it jumps now.
3664 If the old jump target label is unused as a result,
3665 it and the code following it may be deleted.
3667 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
3670 The return value will be 1 if the change was made, 0 if it wasn't (this
3671 can only occur for NLABEL == 0). */
3674 redirect_jump (jump, nlabel)
3677 register rtx olabel = JUMP_LABEL (jump);
3679 if (nlabel == olabel)
3682 if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump))
3685 /* If this is an unconditional branch, delete it from the jump_chain of
3686 OLABEL and add it to the jump_chain of NLABEL (assuming both labels
3687 have UID's in range and JUMP_CHAIN is valid). */
3688 if (jump_chain && (simplejump_p (jump)
3689 || GET_CODE (PATTERN (jump)) == RETURN))
3691 int label_index = nlabel ? INSN_UID (nlabel) : 0;
3693 delete_from_jump_chain (jump);
3694 if (label_index < max_jump_chain
3695 && INSN_UID (jump) < max_jump_chain)
3697 jump_chain[INSN_UID (jump)] = jump_chain[label_index];
3698 jump_chain[label_index] = jump;
3702 JUMP_LABEL (jump) = nlabel;
3704 ++LABEL_NUSES (nlabel);
3706 if (olabel && --LABEL_NUSES (olabel) == 0)
3707 delete_insn (olabel);
3712 /* Delete the instruction JUMP from any jump chain it might be on. */
3715 delete_from_jump_chain (jump)
3719 rtx olabel = JUMP_LABEL (jump);
3721 /* Handle unconditional jumps. */
3722 if (jump_chain && olabel != 0
3723 && INSN_UID (olabel) < max_jump_chain
3724 && simplejump_p (jump))
3725 index = INSN_UID (olabel);
3726 /* Handle return insns. */
3727 else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN)
3731 if (jump_chain[index] == jump)
3732 jump_chain[index] = jump_chain[INSN_UID (jump)];
3737 for (insn = jump_chain[index];
3739 insn = jump_chain[INSN_UID (insn)])
3740 if (jump_chain[INSN_UID (insn)] == jump)
3742 jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)];
3748 /* If NLABEL is nonzero, throughout the rtx at LOC,
3749 alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is
3750 zero, alter (RETURN) to (LABEL_REF NLABEL).
3752 If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check
3753 validity with validate_change. Convert (set (pc) (label_ref olabel))
3756 Return 0 if we found a change we would like to make but it is invalid.
3757 Otherwise, return 1. */
3760 redirect_exp (loc, olabel, nlabel, insn)
3765 register rtx x = *loc;
3766 register RTX_CODE code = GET_CODE (x);
3770 if (code == LABEL_REF)
3772 if (XEXP (x, 0) == olabel)
3775 XEXP (x, 0) = nlabel;
3777 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3781 else if (code == RETURN && olabel == 0)
3783 x = gen_rtx (LABEL_REF, VOIDmode, nlabel);
3784 if (loc == &PATTERN (insn))
3785 x = gen_rtx (SET, VOIDmode, pc_rtx, x);
3786 return validate_change (insn, loc, x, 0);
3789 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
3790 && GET_CODE (SET_SRC (x)) == LABEL_REF
3791 && XEXP (SET_SRC (x), 0) == olabel)
3792 return validate_change (insn, loc, gen_rtx (RETURN, VOIDmode), 0);
3794 fmt = GET_RTX_FORMAT (code);
3795 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3798 if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn))
3803 for (j = 0; j < XVECLEN (x, i); j++)
3804 if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn))
3812 /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump.
3814 If the old jump target label (before the dispatch table) becomes unused,
3815 it and the dispatch table may be deleted. In that case, find the insn
3816 before the jump references that label and delete it and logical successors
3820 redirect_tablejump (jump, nlabel)
3823 register rtx olabel = JUMP_LABEL (jump);
3825 /* Add this jump to the jump_chain of NLABEL. */
3826 if (jump_chain && INSN_UID (nlabel) < max_jump_chain
3827 && INSN_UID (jump) < max_jump_chain)
3829 jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)];
3830 jump_chain[INSN_UID (nlabel)] = jump;
3833 PATTERN (jump) = gen_jump (nlabel);
3834 JUMP_LABEL (jump) = nlabel;
3835 ++LABEL_NUSES (nlabel);
3836 INSN_CODE (jump) = -1;
3838 if (--LABEL_NUSES (olabel) == 0)
3840 delete_labelref_insn (jump, olabel, 0);
3841 delete_insn (olabel);
3845 /* Find the insn referencing LABEL that is a logical predecessor of INSN.
3846 If we found one, delete it and then delete this insn if DELETE_THIS is
3847 non-zero. Return non-zero if INSN or a predecessor references LABEL. */
3850 delete_labelref_insn (insn, label, delete_this)
3857 if (GET_CODE (insn) != NOTE
3858 && reg_mentioned_p (label, PATTERN (insn)))
3869 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
3870 if (delete_labelref_insn (XEXP (link, 0), label, 1))
3884 /* Like rtx_equal_p except that it considers two REGs as equal
3885 if they renumber to the same value and considers two commutative
3886 operations to be the same if the order of the operands has been
3890 rtx_renumbered_equal_p (x, y)
3894 register RTX_CODE code = GET_CODE (x);
3900 if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG))
3901 && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG
3902 && GET_CODE (SUBREG_REG (y)) == REG)))
3904 int reg_x = -1, reg_y = -1;
3905 int word_x = 0, word_y = 0;
3907 if (GET_MODE (x) != GET_MODE (y))
3910 /* If we haven't done any renumbering, don't
3911 make any assumptions. */
3912 if (reg_renumber == 0)
3913 return rtx_equal_p (x, y);
3917 reg_x = REGNO (SUBREG_REG (x));
3918 word_x = SUBREG_WORD (x);
3920 if (reg_renumber[reg_x] >= 0)
3922 reg_x = reg_renumber[reg_x] + word_x;
3930 if (reg_renumber[reg_x] >= 0)
3931 reg_x = reg_renumber[reg_x];
3934 if (GET_CODE (y) == SUBREG)
3936 reg_y = REGNO (SUBREG_REG (y));
3937 word_y = SUBREG_WORD (y);
3939 if (reg_renumber[reg_y] >= 0)
3941 reg_y = reg_renumber[reg_y];
3949 if (reg_renumber[reg_y] >= 0)
3950 reg_y = reg_renumber[reg_y];
3953 return reg_x >= 0 && reg_x == reg_y && word_x == word_y;
3956 /* Now we have disposed of all the cases
3957 in which different rtx codes can match. */
3958 if (code != GET_CODE (y))
3970 return INTVAL (x) == INTVAL (y);
3973 /* We can't assume nonlocal labels have their following insns yet. */
3974 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
3975 return XEXP (x, 0) == XEXP (y, 0);
3977 /* Two label-refs are equivalent if they point at labels
3978 in the same position in the instruction stream. */
3979 return (next_real_insn (XEXP (x, 0))
3980 == next_real_insn (XEXP (y, 0)));
3983 return XSTR (x, 0) == XSTR (y, 0);
3986 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
3988 if (GET_MODE (x) != GET_MODE (y))
3991 /* For commutative operations, the RTX match if the operand match in any
3992 order. Also handle the simple binary and unary cases without a loop. */
3993 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
3994 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
3995 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
3996 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
3997 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
3998 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
3999 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
4000 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
4001 else if (GET_RTX_CLASS (code) == '1')
4002 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
4004 /* Compare the elements. If any pair of corresponding elements
4005 fail to match, return 0 for the whole things. */
4007 fmt = GET_RTX_FORMAT (code);
4008 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4014 if (XWINT (x, i) != XWINT (y, i))
4019 if (XINT (x, i) != XINT (y, i))
4024 if (strcmp (XSTR (x, i), XSTR (y, i)))
4029 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
4034 if (XEXP (x, i) != XEXP (y, i))
4041 if (XVECLEN (x, i) != XVECLEN (y, i))
4043 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4044 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
4055 /* If X is a hard register or equivalent to one or a subregister of one,
4056 return the hard register number. If X is a pseudo register that was not
4057 assigned a hard register, return the pseudo register number. Otherwise,
4058 return -1. Any rtx is valid for X. */
4064 if (GET_CODE (x) == REG)
4066 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
4067 return reg_renumber[REGNO (x)];
4070 if (GET_CODE (x) == SUBREG)
4072 int base = true_regnum (SUBREG_REG (x));
4073 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
4074 return SUBREG_WORD (x) + base;
4079 /* Optimize code of the form:
4081 for (x = a[i]; x; ...)
4083 for (x = a[i]; x; ...)
4087 Loop optimize will change the above code into
4091 { ...; if (! (x = ...)) break; }
4094 { ...; if (! (x = ...)) break; }
4097 In general, if the first test fails, the program can branch
4098 directly to `foo' and skip the second try which is doomed to fail.
4099 We run this after loop optimization and before flow analysis. */
4101 /* When comparing the insn patterns, we track the fact that different
4102 pseudo-register numbers may have been used in each computation.
4103 The following array stores an equivalence -- same_regs[I] == J means
4104 that pseudo register I was used in the first set of tests in a context
4105 where J was used in the second set. We also count the number of such
4106 pending equivalences. If nonzero, the expressions really aren't the
4109 static int *same_regs;
4111 static int num_same_regs;
4113 /* Track any registers modified between the target of the first jump and
4114 the second jump. They never compare equal. */
4116 static char *modified_regs;
4118 /* Record if memory was modified. */
4120 static int modified_mem;
4122 /* Called via note_stores on each insn between the target of the first
4123 branch and the second branch. It marks any changed registers. */
4126 mark_modified_reg (dest, x)
4132 if (GET_CODE (dest) == SUBREG)
4133 dest = SUBREG_REG (dest);
4135 if (GET_CODE (dest) == MEM)
4138 if (GET_CODE (dest) != REG)
4141 regno = REGNO (dest);
4142 if (regno >= FIRST_PSEUDO_REGISTER)
4143 modified_regs[regno] = 1;
4145 for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++)
4146 modified_regs[regno + i] = 1;
4149 /* F is the first insn in the chain of insns. */
4152 thread_jumps (f, max_reg, flag_before_loop)
4155 int flag_before_loop;
4157 /* Basic algorithm is to find a conditional branch,
4158 the label it may branch to, and the branch after
4159 that label. If the two branches test the same condition,
4160 walk back from both branch paths until the insn patterns
4161 differ, or code labels are hit. If we make it back to
4162 the target of the first branch, then we know that the first branch
4163 will either always succeed or always fail depending on the relative
4164 senses of the two branches. So adjust the first branch accordingly
4167 rtx label, b1, b2, t1, t2;
4168 enum rtx_code code1, code2;
4169 rtx b1op0, b1op1, b2op0, b2op1;
4174 /* Allocate register tables and quick-reset table. */
4175 modified_regs = (char *) alloca (max_reg * sizeof (char));
4176 same_regs = (int *) alloca (max_reg * sizeof (int));
4177 all_reset = (int *) alloca (max_reg * sizeof (int));
4178 for (i = 0; i < max_reg; i++)
4185 for (b1 = f; b1; b1 = NEXT_INSN (b1))
4187 /* Get to a candidate branch insn. */
4188 if (GET_CODE (b1) != JUMP_INSN
4189 || ! condjump_p (b1) || simplejump_p (b1)
4190 || JUMP_LABEL (b1) == 0)
4193 bzero (modified_regs, max_reg * sizeof (char));
4196 bcopy ((char *) all_reset, (char *) same_regs,
4197 max_reg * sizeof (int));
4200 label = JUMP_LABEL (b1);
4202 /* Look for a branch after the target. Record any registers and
4203 memory modified between the target and the branch. Stop when we
4204 get to a label since we can't know what was changed there. */
4205 for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2))
4207 if (GET_CODE (b2) == CODE_LABEL)
4210 else if (GET_CODE (b2) == JUMP_INSN)
4212 /* If this is an unconditional jump and is the only use of
4213 its target label, we can follow it. */
4214 if (simplejump_p (b2)
4215 && JUMP_LABEL (b2) != 0
4216 && LABEL_NUSES (JUMP_LABEL (b2)) == 1)
4218 b2 = JUMP_LABEL (b2);
4225 if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN)
4228 if (GET_CODE (b2) == CALL_INSN)
4231 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4232 if (call_used_regs[i] && ! fixed_regs[i]
4233 && i != STACK_POINTER_REGNUM
4234 && i != FRAME_POINTER_REGNUM
4235 && i != HARD_FRAME_POINTER_REGNUM
4236 && i != ARG_POINTER_REGNUM)
4237 modified_regs[i] = 1;
4240 note_stores (PATTERN (b2), mark_modified_reg);
4243 /* Check the next candidate branch insn from the label
4246 || GET_CODE (b2) != JUMP_INSN
4248 || ! condjump_p (b2)
4249 || simplejump_p (b2))
4252 /* Get the comparison codes and operands, reversing the
4253 codes if appropriate. If we don't have comparison codes,
4254 we can't do anything. */
4255 b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0);
4256 b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1);
4257 code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0));
4258 if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx)
4259 code1 = reverse_condition (code1);
4261 b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0);
4262 b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1);
4263 code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0));
4264 if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx)
4265 code2 = reverse_condition (code2);
4267 /* If they test the same things and knowing that B1 branches
4268 tells us whether or not B2 branches, check if we
4269 can thread the branch. */
4270 if (rtx_equal_for_thread_p (b1op0, b2op0, b2)
4271 && rtx_equal_for_thread_p (b1op1, b2op1, b2)
4272 && (comparison_dominates_p (code1, code2)
4273 || comparison_dominates_p (code1, reverse_condition (code2))))
4275 t1 = prev_nonnote_insn (b1);
4276 t2 = prev_nonnote_insn (b2);
4278 while (t1 != 0 && t2 != 0)
4282 /* We have reached the target of the first branch.
4283 If there are no pending register equivalents,
4284 we know that this branch will either always
4285 succeed (if the senses of the two branches are
4286 the same) or always fail (if not). */
4289 if (num_same_regs != 0)
4292 if (comparison_dominates_p (code1, code2))
4293 new_label = JUMP_LABEL (b2);
4295 new_label = get_label_after (b2);
4297 if (JUMP_LABEL (b1) != new_label)
4299 rtx prev = PREV_INSN (new_label);
4301 if (flag_before_loop
4302 && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG)
4304 /* Don't thread to the loop label. If a loop
4305 label is reused, loop optimization will
4306 be disabled for that loop. */
4307 new_label = gen_label_rtx ();
4308 emit_label_after (new_label, PREV_INSN (prev));
4310 changed |= redirect_jump (b1, new_label);
4315 /* If either of these is not a normal insn (it might be
4316 a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs
4317 have already been skipped above.) Similarly, fail
4318 if the insns are different. */
4319 if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN
4320 || recog_memoized (t1) != recog_memoized (t2)
4321 || ! rtx_equal_for_thread_p (PATTERN (t1),
4325 t1 = prev_nonnote_insn (t1);
4326 t2 = prev_nonnote_insn (t2);
4333 /* This is like RTX_EQUAL_P except that it knows about our handling of
4334 possibly equivalent registers and knows to consider volatile and
4335 modified objects as not equal.
4337 YINSN is the insn containing Y. */
4340 rtx_equal_for_thread_p (x, y, yinsn)
4346 register enum rtx_code code;
4349 code = GET_CODE (x);
4350 /* Rtx's of different codes cannot be equal. */
4351 if (code != GET_CODE (y))
4354 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
4355 (REG:SI x) and (REG:HI x) are NOT equivalent. */
4357 if (GET_MODE (x) != GET_MODE (y))
4360 /* For commutative operations, the RTX match if the operand match in any
4361 order. Also handle the simple binary and unary cases without a loop. */
4362 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
4363 return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4364 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn))
4365 || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn)
4366 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn)));
4367 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
4368 return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn)
4369 && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn));
4370 else if (GET_RTX_CLASS (code) == '1')
4371 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4373 /* Handle special-cases first. */
4377 if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)])
4380 /* If neither is user variable or hard register, check for possible
4382 if (REG_USERVAR_P (x) || REG_USERVAR_P (y)
4383 || REGNO (x) < FIRST_PSEUDO_REGISTER
4384 || REGNO (y) < FIRST_PSEUDO_REGISTER)
4387 if (same_regs[REGNO (x)] == -1)
4389 same_regs[REGNO (x)] = REGNO (y);
4392 /* If this is the first time we are seeing a register on the `Y'
4393 side, see if it is the last use. If not, we can't thread the
4394 jump, so mark it as not equivalent. */
4395 if (regno_last_uid[REGNO (y)] != INSN_UID (yinsn))
4401 return (same_regs[REGNO (x)] == REGNO (y));
4406 /* If memory modified or either volatile, not equivalent.
4407 Else, check address. */
4408 if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4411 return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn);
4414 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
4420 /* Cancel a pending `same_regs' if setting equivalenced registers.
4421 Then process source. */
4422 if (GET_CODE (SET_DEST (x)) == REG
4423 && GET_CODE (SET_DEST (y)) == REG)
4425 if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y)))
4427 same_regs[REGNO (SET_DEST (x))] = -1;
4430 else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y)))
4434 if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0)
4437 return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn);
4440 return XEXP (x, 0) == XEXP (y, 0);
4443 return XSTR (x, 0) == XSTR (y, 0);
4449 fmt = GET_RTX_FORMAT (code);
4450 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4455 if (XWINT (x, i) != XWINT (y, i))
4461 if (XINT (x, i) != XINT (y, i))
4467 /* Two vectors must have the same length. */
4468 if (XVECLEN (x, i) != XVECLEN (y, i))
4471 /* And the corresponding elements must match. */
4472 for (j = 0; j < XVECLEN (x, i); j++)
4473 if (rtx_equal_for_thread_p (XVECEXP (x, i, j),
4474 XVECEXP (y, i, j), yinsn) == 0)
4479 if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0)
4485 if (strcmp (XSTR (x, i), XSTR (y, i)))
4490 /* These are just backpointers, so they don't matter. */
4496 /* It is believed that rtx's at this level will never
4497 contain anything but integers and other rtx's,
4498 except for within LABEL_REFs and SYMBOL_REFs. */