1 /* Optimize jump instructions, for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997
3 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This is the pathetic reminder of old fame of the jump-optimization pass
23 of the compiler. Now it contains basically set of utility function to
26 Each CODE_LABEL has a count of the times it is used
27 stored in the LABEL_NUSES internal field, and each JUMP_INSN
28 has one label that it refers to stored in the
29 JUMP_LABEL internal field. With this we can detect labels that
30 become unused because of the deletion of all the jumps that
31 formerly used them. The JUMP_LABEL info is sometimes looked
34 The subroutines redirect_jump and invert_jump are used
35 from other passes as well. */
39 #include "coretypes.h"
44 #include "hard-reg-set.h"
46 #include "insn-config.h"
47 #include "insn-attr.h"
53 #include "diagnostic.h"
59 /* Optimize jump y; x: ... y: jumpif... x?
60 Don't know if it is worth bothering with. */
61 /* Optimize two cases of conditional jump to conditional jump?
62 This can never delete any instruction or make anything dead,
63 or even change what is live at any point.
64 So perhaps let combiner do it. */
66 static void init_label_info (rtx);
67 static void mark_all_labels (rtx);
68 static void delete_computation (rtx);
69 static void redirect_exp_1 (rtx *, rtx, rtx, rtx);
70 static int redirect_exp (rtx, rtx, rtx);
71 static void invert_exp_1 (rtx);
72 static int invert_exp (rtx);
73 static int returnjump_p_1 (rtx *, void *);
74 static void delete_prior_computation (rtx, rtx);
76 /* Alternate entry into the jump optimizer. This entry point only rebuilds
77 the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
80 rebuild_jump_labels (rtx f)
84 timevar_push (TV_REBUILD_JUMP);
88 /* Keep track of labels used from static data; we don't track them
89 closely enough to delete them here, so make sure their reference
90 count doesn't drop to zero. */
92 for (insn = forced_labels; insn; insn = XEXP (insn, 1))
93 if (LABEL_P (XEXP (insn, 0)))
94 LABEL_NUSES (XEXP (insn, 0))++;
95 timevar_pop (TV_REBUILD_JUMP);
98 /* Some old code expects exactly one BARRIER as the NEXT_INSN of a
99 non-fallthru insn. This is not generally true, as multiple barriers
100 may have crept in, or the BARRIER may be separated from the last
101 real insn by one or more NOTEs.
103 This simple pass moves barriers and removes duplicates so that the
107 cleanup_barriers (void)
109 rtx insn, next, prev;
110 for (insn = get_insns (); insn; insn = next)
112 next = NEXT_INSN (insn);
113 if (BARRIER_P (insn))
115 prev = prev_nonnote_insn (insn);
116 if (BARRIER_P (prev))
118 else if (prev != PREV_INSN (insn))
119 reorder_insns (insn, insn, prev);
125 purge_line_number_notes (rtx f)
129 /* Delete extraneous line number notes.
130 Note that two consecutive notes for different lines are not really
131 extraneous. There should be some indication where that line belonged,
132 even if it became empty. */
134 for (insn = f; insn; insn = NEXT_INSN (insn))
137 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
138 /* Any previous line note was for the prologue; gdb wants a new
139 note after the prologue even if it is for the same line. */
140 last_note = NULL_RTX;
141 else if (NOTE_LINE_NUMBER (insn) >= 0)
143 /* Delete this note if it is identical to previous note. */
145 #ifdef USE_MAPPED_LOCATION
146 && NOTE_SOURCE_LOCATION (insn) == NOTE_SOURCE_LOCATION (last_note)
148 && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
149 && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note)
153 delete_related_insns (insn);
162 /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
163 notes whose labels don't occur in the insn any more. Returns the
164 largest INSN_UID found. */
166 init_label_info (rtx f)
170 for (insn = f; insn; insn = NEXT_INSN (insn))
172 LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
173 else if (JUMP_P (insn))
174 JUMP_LABEL (insn) = 0;
175 else if (NONJUMP_INSN_P (insn) || CALL_P (insn))
179 for (note = REG_NOTES (insn); note; note = next)
181 next = XEXP (note, 1);
182 if (REG_NOTE_KIND (note) == REG_LABEL
183 && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
184 remove_note (insn, note);
189 /* Mark the label each jump jumps to.
190 Combine consecutive labels, and count uses of labels. */
193 mark_all_labels (rtx f)
197 for (insn = f; insn; insn = NEXT_INSN (insn))
200 mark_jump_label (PATTERN (insn), insn, 0);
201 if (! INSN_DELETED_P (insn) && JUMP_P (insn))
203 /* When we know the LABEL_REF contained in a REG used in
204 an indirect jump, we'll have a REG_LABEL note so that
205 flow can tell where it's going. */
206 if (JUMP_LABEL (insn) == 0)
208 rtx label_note = find_reg_note (insn, REG_LABEL, NULL_RTX);
211 /* But a LABEL_REF around the REG_LABEL note, so
212 that we can canonicalize it. */
213 rtx label_ref = gen_rtx_LABEL_REF (VOIDmode,
214 XEXP (label_note, 0));
216 mark_jump_label (label_ref, insn, 0);
217 XEXP (label_note, 0) = XEXP (label_ref, 0);
218 JUMP_LABEL (insn) = XEXP (label_note, 0);
225 /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, loop-end,
226 notes between START and END out before START. START and END may be such
227 notes. Returns the values of the new starting and ending insns, which
228 may be different if the original ones were such notes.
229 Return true if there were only such notes and no real instructions. */
232 squeeze_notes (rtx* startp, rtx* endp)
240 rtx past_end = NEXT_INSN (end);
242 for (insn = start; insn != past_end; insn = next)
244 next = NEXT_INSN (insn);
246 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
247 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
248 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
249 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END))
255 rtx prev = PREV_INSN (insn);
256 PREV_INSN (insn) = PREV_INSN (start);
257 NEXT_INSN (insn) = start;
258 NEXT_INSN (PREV_INSN (insn)) = insn;
259 PREV_INSN (NEXT_INSN (insn)) = insn;
260 NEXT_INSN (prev) = next;
261 PREV_INSN (next) = prev;
268 /* There were no real instructions. */
269 if (start == past_end)
279 /* Return the label before INSN, or put a new label there. */
282 get_label_before (rtx insn)
286 /* Find an existing label at this point
287 or make a new one if there is none. */
288 label = prev_nonnote_insn (insn);
290 if (label == 0 || !LABEL_P (label))
292 rtx prev = PREV_INSN (insn);
294 label = gen_label_rtx ();
295 emit_label_after (label, prev);
296 LABEL_NUSES (label) = 0;
301 /* Return the label after INSN, or put a new label there. */
304 get_label_after (rtx insn)
308 /* Find an existing label at this point
309 or make a new one if there is none. */
310 label = next_nonnote_insn (insn);
312 if (label == 0 || !LABEL_P (label))
314 label = gen_label_rtx ();
315 emit_label_after (label, insn);
316 LABEL_NUSES (label) = 0;
321 /* Given a comparison (CODE ARG0 ARG1), inside an insn, INSN, return a code
322 of reversed comparison if it is possible to do so. Otherwise return UNKNOWN.
323 UNKNOWN may be returned in case we are having CC_MODE compare and we don't
324 know whether it's source is floating point or integer comparison. Machine
325 description should define REVERSIBLE_CC_MODE and REVERSE_CONDITION macros
326 to help this function avoid overhead in these cases. */
328 reversed_comparison_code_parts (enum rtx_code code, rtx arg0, rtx arg1, rtx insn)
330 enum machine_mode mode;
332 /* If this is not actually a comparison, we can't reverse it. */
333 if (GET_RTX_CLASS (code) != RTX_COMPARE
334 && GET_RTX_CLASS (code) != RTX_COMM_COMPARE)
337 mode = GET_MODE (arg0);
338 if (mode == VOIDmode)
339 mode = GET_MODE (arg1);
341 /* First see if machine description supplies us way to reverse the
342 comparison. Give it priority over everything else to allow
343 machine description to do tricks. */
344 if (GET_MODE_CLASS (mode) == MODE_CC
345 && REVERSIBLE_CC_MODE (mode))
347 #ifdef REVERSE_CONDITION
348 return REVERSE_CONDITION (code, mode);
350 return reverse_condition (code);
353 /* Try a few special cases based on the comparison code. */
362 /* It is always safe to reverse EQ and NE, even for the floating
363 point. Similarly the unsigned comparisons are never used for
364 floating point so we can reverse them in the default way. */
365 return reverse_condition (code);
370 /* In case we already see unordered comparison, we can be sure to
371 be dealing with floating point so we don't need any more tests. */
372 return reverse_condition_maybe_unordered (code);
377 /* We don't have safe way to reverse these yet. */
383 if (GET_MODE_CLASS (mode) == MODE_CC || CC0_P (arg0))
386 /* Try to search for the comparison to determine the real mode.
387 This code is expensive, but with sane machine description it
388 will be never used, since REVERSIBLE_CC_MODE will return true
393 for (prev = prev_nonnote_insn (insn);
394 prev != 0 && !LABEL_P (prev);
395 prev = prev_nonnote_insn (prev))
397 rtx set = set_of (arg0, prev);
398 if (set && GET_CODE (set) == SET
399 && rtx_equal_p (SET_DEST (set), arg0))
401 rtx src = SET_SRC (set);
403 if (GET_CODE (src) == COMPARE)
405 rtx comparison = src;
406 arg0 = XEXP (src, 0);
407 mode = GET_MODE (arg0);
408 if (mode == VOIDmode)
409 mode = GET_MODE (XEXP (comparison, 1));
412 /* We can get past reg-reg moves. This may be useful for model
413 of i387 comparisons that first move flag registers around. */
420 /* If register is clobbered in some ununderstandable way,
427 /* Test for an integer condition, or a floating-point comparison
428 in which NaNs can be ignored. */
429 if (GET_CODE (arg0) == CONST_INT
430 || (GET_MODE (arg0) != VOIDmode
431 && GET_MODE_CLASS (mode) != MODE_CC
432 && !HONOR_NANS (mode)))
433 return reverse_condition (code);
438 /* A wrapper around the previous function to take COMPARISON as rtx
439 expression. This simplifies many callers. */
441 reversed_comparison_code (rtx comparison, rtx insn)
443 if (!COMPARISON_P (comparison))
445 return reversed_comparison_code_parts (GET_CODE (comparison),
446 XEXP (comparison, 0),
447 XEXP (comparison, 1), insn);
450 /* Given an rtx-code for a comparison, return the code for the negated
451 comparison. If no such code exists, return UNKNOWN.
453 WATCH OUT! reverse_condition is not safe to use on a jump that might
454 be acting on the results of an IEEE floating point comparison, because
455 of the special treatment of non-signaling nans in comparisons.
456 Use reversed_comparison_code instead. */
459 reverse_condition (enum rtx_code code)
501 /* Similar, but we're allowed to generate unordered comparisons, which
502 makes it safe for IEEE floating-point. Of course, we have to recognize
503 that the target will support them too... */
506 reverse_condition_maybe_unordered (enum rtx_code code)
544 /* Similar, but return the code when two operands of a comparison are swapped.
545 This IS safe for IEEE floating-point. */
548 swap_condition (enum rtx_code code)
590 /* Given a comparison CODE, return the corresponding unsigned comparison.
591 If CODE is an equality comparison or already an unsigned comparison,
595 unsigned_condition (enum rtx_code code)
621 /* Similarly, return the signed version of a comparison. */
624 signed_condition (enum rtx_code code)
650 /* Return nonzero if CODE1 is more strict than CODE2, i.e., if the
651 truth of CODE1 implies the truth of CODE2. */
654 comparison_dominates_p (enum rtx_code code1, enum rtx_code code2)
656 /* UNKNOWN comparison codes can happen as a result of trying to revert
658 They can't match anything, so we have to reject them here. */
659 if (code1 == UNKNOWN || code2 == UNKNOWN)
668 if (code2 == UNLE || code2 == UNGE)
673 if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
679 if (code2 == UNLE || code2 == NE)
684 if (code2 == LE || code2 == NE || code2 == ORDERED || code2 == LTGT)
689 if (code2 == UNGE || code2 == NE)
694 if (code2 == GE || code2 == NE || code2 == ORDERED || code2 == LTGT)
700 if (code2 == ORDERED)
705 if (code2 == NE || code2 == ORDERED)
710 if (code2 == LEU || code2 == NE)
715 if (code2 == GEU || code2 == NE)
720 if (code2 == NE || code2 == UNEQ || code2 == UNLE || code2 == UNLT
721 || code2 == UNGE || code2 == UNGT)
732 /* Return 1 if INSN is an unconditional jump and nothing else. */
735 simplejump_p (rtx insn)
737 return (JUMP_P (insn)
738 && GET_CODE (PATTERN (insn)) == SET
739 && GET_CODE (SET_DEST (PATTERN (insn))) == PC
740 && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
743 /* Return nonzero if INSN is a (possibly) conditional jump
746 Use of this function is deprecated, since we need to support combined
747 branch and compare insns. Use any_condjump_p instead whenever possible. */
750 condjump_p (rtx insn)
752 rtx x = PATTERN (insn);
754 if (GET_CODE (x) != SET
755 || GET_CODE (SET_DEST (x)) != PC)
759 if (GET_CODE (x) == LABEL_REF)
762 return (GET_CODE (x) == IF_THEN_ELSE
763 && ((GET_CODE (XEXP (x, 2)) == PC
764 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
765 || GET_CODE (XEXP (x, 1)) == RETURN))
766 || (GET_CODE (XEXP (x, 1)) == PC
767 && (GET_CODE (XEXP (x, 2)) == LABEL_REF
768 || GET_CODE (XEXP (x, 2)) == RETURN))));
773 /* Return nonzero if INSN is a (possibly) conditional jump inside a
776 Use this function is deprecated, since we need to support combined
777 branch and compare insns. Use any_condjump_p instead whenever possible. */
780 condjump_in_parallel_p (rtx insn)
782 rtx x = PATTERN (insn);
784 if (GET_CODE (x) != PARALLEL)
787 x = XVECEXP (x, 0, 0);
789 if (GET_CODE (x) != SET)
791 if (GET_CODE (SET_DEST (x)) != PC)
793 if (GET_CODE (SET_SRC (x)) == LABEL_REF)
795 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
797 if (XEXP (SET_SRC (x), 2) == pc_rtx
798 && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
799 || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN))
801 if (XEXP (SET_SRC (x), 1) == pc_rtx
802 && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
803 || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN))
808 /* Return set of PC, otherwise NULL. */
816 pat = PATTERN (insn);
818 /* The set is allowed to appear either as the insn pattern or
819 the first set in a PARALLEL. */
820 if (GET_CODE (pat) == PARALLEL)
821 pat = XVECEXP (pat, 0, 0);
822 if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
828 /* Return true when insn is an unconditional direct jump,
829 possibly bundled inside a PARALLEL. */
832 any_uncondjump_p (rtx insn)
834 rtx x = pc_set (insn);
837 if (GET_CODE (SET_SRC (x)) != LABEL_REF)
839 if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
844 /* Return true when insn is a conditional jump. This function works for
845 instructions containing PC sets in PARALLELs. The instruction may have
846 various other effects so before removing the jump you must verify
849 Note that unlike condjump_p it returns false for unconditional jumps. */
852 any_condjump_p (rtx insn)
854 rtx x = pc_set (insn);
859 if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
862 a = GET_CODE (XEXP (SET_SRC (x), 1));
863 b = GET_CODE (XEXP (SET_SRC (x), 2));
865 return ((b == PC && (a == LABEL_REF || a == RETURN))
866 || (a == PC && (b == LABEL_REF || b == RETURN)));
869 /* Return the label of a conditional jump. */
872 condjump_label (rtx insn)
874 rtx x = pc_set (insn);
879 if (GET_CODE (x) == LABEL_REF)
881 if (GET_CODE (x) != IF_THEN_ELSE)
883 if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
885 if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
890 /* Return true if INSN is a (possibly conditional) return insn. */
893 returnjump_p_1 (rtx *loc, void *data ATTRIBUTE_UNUSED)
897 return x && (GET_CODE (x) == RETURN
898 || (GET_CODE (x) == SET && SET_IS_RETURN_P (x)));
902 returnjump_p (rtx insn)
906 return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
909 /* Return true if INSN is a jump that only transfers control and
913 onlyjump_p (rtx insn)
920 set = single_set (insn);
923 if (GET_CODE (SET_DEST (set)) != PC)
925 if (side_effects_p (SET_SRC (set)))
933 /* Return nonzero if X is an RTX that only sets the condition codes
934 and has no side effects. */
937 only_sets_cc0_p (rtx x)
945 return sets_cc0_p (x) == 1 && ! side_effects_p (x);
948 /* Return 1 if X is an RTX that does nothing but set the condition codes
949 and CLOBBER or USE registers.
950 Return -1 if X does explicitly set the condition codes,
951 but also does other things. */
962 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
964 if (GET_CODE (x) == PARALLEL)
968 int other_things = 0;
969 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
971 if (GET_CODE (XVECEXP (x, 0, i)) == SET
972 && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
974 else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
977 return ! sets_cc0 ? 0 : other_things ? -1 : 1;
983 /* Follow any unconditional jump at LABEL;
984 return the ultimate label reached by any such chain of jumps.
985 Return null if the chain ultimately leads to a return instruction.
986 If LABEL is not followed by a jump, return LABEL.
987 If the chain loops or we can't find end, return LABEL,
988 since that tells caller to avoid changing the insn.
990 If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or
994 follow_jumps (rtx label)
1003 && (insn = next_active_insn (value)) != 0
1005 && ((JUMP_LABEL (insn) != 0 && any_uncondjump_p (insn)
1006 && onlyjump_p (insn))
1007 || GET_CODE (PATTERN (insn)) == RETURN)
1008 && (next = NEXT_INSN (insn))
1009 && BARRIER_P (next));
1012 /* Don't chain through the insn that jumps into a loop
1013 from outside the loop,
1014 since that would create multiple loop entry jumps
1015 and prevent loop optimization. */
1017 if (!reload_completed)
1018 for (tem = value; tem != insn; tem = NEXT_INSN (tem))
1020 && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG
1021 /* ??? Optional. Disables some optimizations, but makes
1022 gcov output more accurate with -O. */
1023 || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0)))
1026 /* If we have found a cycle, make the insn jump to itself. */
1027 if (JUMP_LABEL (insn) == label)
1030 tem = next_active_insn (JUMP_LABEL (insn));
1031 if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
1032 || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
1035 value = JUMP_LABEL (insn);
1043 /* Find all CODE_LABELs referred to in X, and increment their use counts.
1044 If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced
1045 in INSN, then store one of them in JUMP_LABEL (INSN).
1046 If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL
1047 referenced in INSN, add a REG_LABEL note containing that label to INSN.
1048 Also, when there are consecutive labels, canonicalize on the last of them.
1050 Note that two labels separated by a loop-beginning note
1051 must be kept distinct if we have not yet done loop-optimization,
1052 because the gap between them is where loop-optimize
1053 will want to move invariant code to. CROSS_JUMP tells us
1054 that loop-optimization is done with. */
1057 mark_jump_label (rtx x, rtx insn, int in_mem)
1059 RTX_CODE code = GET_CODE (x);
1082 /* If this is a constant-pool reference, see if it is a label. */
1083 if (CONSTANT_POOL_ADDRESS_P (x))
1084 mark_jump_label (get_pool_constant (x), insn, in_mem);
1089 rtx label = XEXP (x, 0);
1091 /* Ignore remaining references to unreachable labels that
1092 have been deleted. */
1094 && NOTE_LINE_NUMBER (label) == NOTE_INSN_DELETED_LABEL)
1097 if (!LABEL_P (label))
1100 /* Ignore references to labels of containing functions. */
1101 if (LABEL_REF_NONLOCAL_P (x))
1104 XEXP (x, 0) = label;
1105 if (! insn || ! INSN_DELETED_P (insn))
1106 ++LABEL_NUSES (label);
1111 JUMP_LABEL (insn) = label;
1114 /* Add a REG_LABEL note for LABEL unless there already
1115 is one. All uses of a label, except for labels
1116 that are the targets of jumps, must have a
1118 if (! find_reg_note (insn, REG_LABEL, label))
1119 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
1126 /* Do walk the labels in a vector, but not the first operand of an
1127 ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */
1130 if (! INSN_DELETED_P (insn))
1132 int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;
1134 for (i = 0; i < XVECLEN (x, eltnum); i++)
1135 mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, in_mem);
1143 fmt = GET_RTX_FORMAT (code);
1144 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1147 mark_jump_label (XEXP (x, i), insn, in_mem);
1148 else if (fmt[i] == 'E')
1151 for (j = 0; j < XVECLEN (x, i); j++)
1152 mark_jump_label (XVECEXP (x, i, j), insn, in_mem);
1157 /* If all INSN does is set the pc, delete it,
1158 and delete the insn that set the condition codes for it
1159 if that's what the previous thing was. */
1162 delete_jump (rtx insn)
1164 rtx set = single_set (insn);
1166 if (set && GET_CODE (SET_DEST (set)) == PC)
1167 delete_computation (insn);
1170 /* Recursively delete prior insns that compute the value (used only by INSN
1171 which the caller is deleting) stored in the register mentioned by NOTE
1172 which is a REG_DEAD note associated with INSN. */
1175 delete_prior_computation (rtx note, rtx insn)
1178 rtx reg = XEXP (note, 0);
1180 for (our_prev = prev_nonnote_insn (insn);
1181 our_prev && (NONJUMP_INSN_P (our_prev)
1182 || CALL_P (our_prev));
1183 our_prev = prev_nonnote_insn (our_prev))
1185 rtx pat = PATTERN (our_prev);
1187 /* If we reach a CALL which is not calling a const function
1188 or the callee pops the arguments, then give up. */
1189 if (CALL_P (our_prev)
1190 && (! CONST_OR_PURE_CALL_P (our_prev)
1191 || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
1194 /* If we reach a SEQUENCE, it is too complex to try to
1195 do anything with it, so give up. We can be run during
1196 and after reorg, so SEQUENCE rtl can legitimately show
1198 if (GET_CODE (pat) == SEQUENCE)
1201 if (GET_CODE (pat) == USE
1202 && NONJUMP_INSN_P (XEXP (pat, 0)))
1203 /* reorg creates USEs that look like this. We leave them
1204 alone because reorg needs them for its own purposes. */
1207 if (reg_set_p (reg, pat))
1209 if (side_effects_p (pat) && !CALL_P (our_prev))
1212 if (GET_CODE (pat) == PARALLEL)
1214 /* If we find a SET of something else, we can't
1219 for (i = 0; i < XVECLEN (pat, 0); i++)
1221 rtx part = XVECEXP (pat, 0, i);
1223 if (GET_CODE (part) == SET
1224 && SET_DEST (part) != reg)
1228 if (i == XVECLEN (pat, 0))
1229 delete_computation (our_prev);
1231 else if (GET_CODE (pat) == SET
1232 && REG_P (SET_DEST (pat)))
1234 int dest_regno = REGNO (SET_DEST (pat));
1237 + (dest_regno < FIRST_PSEUDO_REGISTER
1238 ? hard_regno_nregs[dest_regno]
1239 [GET_MODE (SET_DEST (pat))] : 1));
1240 int regno = REGNO (reg);
1243 + (regno < FIRST_PSEUDO_REGISTER
1244 ? hard_regno_nregs[regno][GET_MODE (reg)] : 1));
1246 if (dest_regno >= regno
1247 && dest_endregno <= endregno)
1248 delete_computation (our_prev);
1250 /* We may have a multi-word hard register and some, but not
1251 all, of the words of the register are needed in subsequent
1252 insns. Write REG_UNUSED notes for those parts that were not
1254 else if (dest_regno <= regno
1255 && dest_endregno >= endregno)
1259 REG_NOTES (our_prev)
1260 = gen_rtx_EXPR_LIST (REG_UNUSED, reg,
1261 REG_NOTES (our_prev));
1263 for (i = dest_regno; i < dest_endregno; i++)
1264 if (! find_regno_note (our_prev, REG_UNUSED, i))
1267 if (i == dest_endregno)
1268 delete_computation (our_prev);
1275 /* If PAT references the register that dies here, it is an
1276 additional use. Hence any prior SET isn't dead. However, this
1277 insn becomes the new place for the REG_DEAD note. */
1278 if (reg_overlap_mentioned_p (reg, pat))
1280 XEXP (note, 1) = REG_NOTES (our_prev);
1281 REG_NOTES (our_prev) = note;
1287 /* Delete INSN and recursively delete insns that compute values used only
1288 by INSN. This uses the REG_DEAD notes computed during flow analysis.
1289 If we are running before flow.c, we need do nothing since flow.c will
1290 delete dead code. We also can't know if the registers being used are
1291 dead or not at this point.
1293 Otherwise, look at all our REG_DEAD notes. If a previous insn does
1294 nothing other than set a register that dies in this insn, we can delete
1297 On machines with CC0, if CC0 is used in this insn, we may be able to
1298 delete the insn that set it. */
1301 delete_computation (rtx insn)
1306 if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
1308 rtx prev = prev_nonnote_insn (insn);
1309 /* We assume that at this stage
1310 CC's are always set explicitly
1311 and always immediately before the jump that
1312 will use them. So if the previous insn
1313 exists to set the CC's, delete it
1314 (unless it performs auto-increments, etc.). */
1315 if (prev && NONJUMP_INSN_P (prev)
1316 && sets_cc0_p (PATTERN (prev)))
1318 if (sets_cc0_p (PATTERN (prev)) > 0
1319 && ! side_effects_p (PATTERN (prev)))
1320 delete_computation (prev);
1322 /* Otherwise, show that cc0 won't be used. */
1323 REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
1324 cc0_rtx, REG_NOTES (prev));
1329 for (note = REG_NOTES (insn); note; note = next)
1331 next = XEXP (note, 1);
1333 if (REG_NOTE_KIND (note) != REG_DEAD
1334 /* Verify that the REG_NOTE is legitimate. */
1335 || !REG_P (XEXP (note, 0)))
1338 delete_prior_computation (note, insn);
1341 delete_related_insns (insn);
1344 /* Delete insn INSN from the chain of insns and update label ref counts
1345 and delete insns now unreachable.
1347 Returns the first insn after INSN that was not deleted.
1349 Usage of this instruction is deprecated. Use delete_insn instead and
1350 subsequent cfg_cleanup pass to delete unreachable code if needed. */
1353 delete_related_insns (rtx insn)
1355 int was_code_label = (LABEL_P (insn));
1357 rtx next = NEXT_INSN (insn), prev = PREV_INSN (insn);
1359 while (next && INSN_DELETED_P (next))
1360 next = NEXT_INSN (next);
1362 /* This insn is already deleted => return first following nondeleted. */
1363 if (INSN_DELETED_P (insn))
1368 /* If instruction is followed by a barrier,
1369 delete the barrier too. */
1371 if (next != 0 && BARRIER_P (next))
1374 /* If deleting a jump, decrement the count of the label,
1375 and delete the label if it is now unused. */
1377 if (JUMP_P (insn) && JUMP_LABEL (insn))
1379 rtx lab = JUMP_LABEL (insn), lab_next;
1381 if (LABEL_NUSES (lab) == 0)
1383 /* This can delete NEXT or PREV,
1384 either directly if NEXT is JUMP_LABEL (INSN),
1385 or indirectly through more levels of jumps. */
1386 delete_related_insns (lab);
1388 /* I feel a little doubtful about this loop,
1389 but I see no clean and sure alternative way
1390 to find the first insn after INSN that is not now deleted.
1391 I hope this works. */
1392 while (next && INSN_DELETED_P (next))
1393 next = NEXT_INSN (next);
1396 else if (tablejump_p (insn, NULL, &lab_next))
1398 /* If we're deleting the tablejump, delete the dispatch table.
1399 We may not be able to kill the label immediately preceding
1400 just yet, as it might be referenced in code leading up to
1402 delete_related_insns (lab_next);
1406 /* Likewise if we're deleting a dispatch table. */
1409 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
1410 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
1412 rtx pat = PATTERN (insn);
1413 int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1414 int len = XVECLEN (pat, diff_vec_p);
1416 for (i = 0; i < len; i++)
1417 if (LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
1418 delete_related_insns (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
1419 while (next && INSN_DELETED_P (next))
1420 next = NEXT_INSN (next);
1424 /* Likewise for an ordinary INSN / CALL_INSN with a REG_LABEL note. */
1425 if (NONJUMP_INSN_P (insn) || CALL_P (insn))
1426 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
1427 if (REG_NOTE_KIND (note) == REG_LABEL
1428 /* This could also be a NOTE_INSN_DELETED_LABEL note. */
1429 && LABEL_P (XEXP (note, 0)))
1430 if (LABEL_NUSES (XEXP (note, 0)) == 0)
1431 delete_related_insns (XEXP (note, 0));
1433 while (prev && (INSN_DELETED_P (prev) || NOTE_P (prev)))
1434 prev = PREV_INSN (prev);
1436 /* If INSN was a label and a dispatch table follows it,
1437 delete the dispatch table. The tablejump must have gone already.
1438 It isn't useful to fall through into a table. */
1441 && NEXT_INSN (insn) != 0
1442 && JUMP_P (NEXT_INSN (insn))
1443 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
1444 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
1445 next = delete_related_insns (NEXT_INSN (insn));
1447 /* If INSN was a label, delete insns following it if now unreachable. */
1449 if (was_code_label && prev && BARRIER_P (prev))
1454 code = GET_CODE (next);
1456 && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END)
1457 next = NEXT_INSN (next);
1458 /* Keep going past other deleted labels to delete what follows. */
1459 else if (code == CODE_LABEL && INSN_DELETED_P (next))
1460 next = NEXT_INSN (next);
1461 else if (code == BARRIER || INSN_P (next))
1462 /* Note: if this deletes a jump, it can cause more
1463 deletion of unreachable code, after a different label.
1464 As long as the value from this recursive call is correct,
1465 this invocation functions correctly. */
1466 next = delete_related_insns (next);
1475 /* Delete a range of insns from FROM to TO, inclusive.
1476 This is for the sake of peephole optimization, so assume
1477 that whatever these insns do will still be done by a new
1478 peephole insn that will replace them. */
1481 delete_for_peephole (rtx from, rtx to)
1487 rtx next = NEXT_INSN (insn);
1488 rtx prev = PREV_INSN (insn);
1492 INSN_DELETED_P (insn) = 1;
1494 /* Patch this insn out of the chain. */
1495 /* We don't do this all at once, because we
1496 must preserve all NOTEs. */
1498 NEXT_INSN (prev) = next;
1501 PREV_INSN (next) = prev;
1509 /* Note that if TO is an unconditional jump
1510 we *do not* delete the BARRIER that follows,
1511 since the peephole that replaces this sequence
1512 is also an unconditional jump in that case. */
1515 /* Throughout LOC, redirect OLABEL to NLABEL. Treat null OLABEL or
1516 NLABEL as a return. Accrue modifications into the change group. */
1519 redirect_exp_1 (rtx *loc, rtx olabel, rtx nlabel, rtx insn)
1522 RTX_CODE code = GET_CODE (x);
1526 if (code == LABEL_REF)
1528 if (XEXP (x, 0) == olabel)
1532 n = gen_rtx_LABEL_REF (VOIDmode, nlabel);
1534 n = gen_rtx_RETURN (VOIDmode);
1536 validate_change (insn, loc, n, 1);
1540 else if (code == RETURN && olabel == 0)
1542 x = gen_rtx_LABEL_REF (VOIDmode, nlabel);
1543 if (loc == &PATTERN (insn))
1544 x = gen_rtx_SET (VOIDmode, pc_rtx, x);
1545 validate_change (insn, loc, x, 1);
1549 if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx
1550 && GET_CODE (SET_SRC (x)) == LABEL_REF
1551 && XEXP (SET_SRC (x), 0) == olabel)
1553 validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 1);
1557 fmt = GET_RTX_FORMAT (code);
1558 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1561 redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
1562 else if (fmt[i] == 'E')
1565 for (j = 0; j < XVECLEN (x, i); j++)
1566 redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
1571 /* Similar, but apply the change group and report success or failure. */
1574 redirect_exp (rtx olabel, rtx nlabel, rtx insn)
1578 if (GET_CODE (PATTERN (insn)) == PARALLEL)
1579 loc = &XVECEXP (PATTERN (insn), 0, 0);
1581 loc = &PATTERN (insn);
1583 redirect_exp_1 (loc, olabel, nlabel, insn);
1584 if (num_validated_changes () == 0)
1587 return apply_change_group ();
1590 /* Make JUMP go to NLABEL instead of where it jumps now. Accrue
1591 the modifications into the change group. Return false if we did
1592 not see how to do that. */
1595 redirect_jump_1 (rtx jump, rtx nlabel)
1597 int ochanges = num_validated_changes ();
1600 if (GET_CODE (PATTERN (jump)) == PARALLEL)
1601 loc = &XVECEXP (PATTERN (jump), 0, 0);
1603 loc = &PATTERN (jump);
1605 redirect_exp_1 (loc, JUMP_LABEL (jump), nlabel, jump);
1606 return num_validated_changes () > ochanges;
1609 /* Make JUMP go to NLABEL instead of where it jumps now. If the old
1610 jump target label is unused as a result, it and the code following
1613 If NLABEL is zero, we are to turn the jump into a (possibly conditional)
1616 The return value will be 1 if the change was made, 0 if it wasn't
1617 (this can only occur for NLABEL == 0). */
1620 redirect_jump (rtx jump, rtx nlabel, int delete_unused)
1622 rtx olabel = JUMP_LABEL (jump);
1625 if (nlabel == olabel)
1628 if (! redirect_exp (olabel, nlabel, jump))
1631 JUMP_LABEL (jump) = nlabel;
1633 ++LABEL_NUSES (nlabel);
1635 /* Update labels in any REG_EQUAL note. */
1636 if ((note = find_reg_note (jump, REG_EQUAL, NULL_RTX)) != NULL_RTX)
1638 if (nlabel && olabel)
1640 rtx dest = XEXP (note, 0);
1642 if (GET_CODE (dest) == IF_THEN_ELSE)
1644 if (GET_CODE (XEXP (dest, 1)) == LABEL_REF
1645 && XEXP (XEXP (dest, 1), 0) == olabel)
1646 XEXP (XEXP (dest, 1), 0) = nlabel;
1647 if (GET_CODE (XEXP (dest, 2)) == LABEL_REF
1648 && XEXP (XEXP (dest, 2), 0) == olabel)
1649 XEXP (XEXP (dest, 2), 0) = nlabel;
1652 remove_note (jump, note);
1655 remove_note (jump, note);
1658 /* If we're eliding the jump over exception cleanups at the end of a
1659 function, move the function end note so that -Wreturn-type works. */
1660 if (olabel && nlabel
1661 && NEXT_INSN (olabel)
1662 && NOTE_P (NEXT_INSN (olabel))
1663 && NOTE_LINE_NUMBER (NEXT_INSN (olabel)) == NOTE_INSN_FUNCTION_END)
1664 emit_note_after (NOTE_INSN_FUNCTION_END, nlabel);
1666 if (olabel && --LABEL_NUSES (olabel) == 0 && delete_unused
1667 /* Undefined labels will remain outside the insn stream. */
1668 && INSN_UID (olabel))
1669 delete_related_insns (olabel);
1674 /* Invert the jump condition of rtx X contained in jump insn, INSN.
1675 Accrue the modifications into the change group. */
1678 invert_exp_1 (rtx insn)
1681 rtx x = pc_set (insn);
1687 code = GET_CODE (x);
1689 if (code == IF_THEN_ELSE)
1691 rtx comp = XEXP (x, 0);
1693 enum rtx_code reversed_code;
1695 /* We can do this in two ways: The preferable way, which can only
1696 be done if this is not an integer comparison, is to reverse
1697 the comparison code. Otherwise, swap the THEN-part and ELSE-part
1698 of the IF_THEN_ELSE. If we can't do either, fail. */
1700 reversed_code = reversed_comparison_code (comp, insn);
1702 if (reversed_code != UNKNOWN)
1704 validate_change (insn, &XEXP (x, 0),
1705 gen_rtx_fmt_ee (reversed_code,
1706 GET_MODE (comp), XEXP (comp, 0),
1713 validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
1714 validate_change (insn, &XEXP (x, 2), tem, 1);
1720 /* Invert the jump condition of conditional jump insn, INSN.
1722 Return 1 if we can do so, 0 if we cannot find a way to do so that
1723 matches a pattern. */
1726 invert_exp (rtx insn)
1728 invert_exp_1 (insn);
1729 if (num_validated_changes () == 0)
1732 return apply_change_group ();
1735 /* Invert the condition of the jump JUMP, and make it jump to label
1736 NLABEL instead of where it jumps now. Accrue changes into the
1737 change group. Return false if we didn't see how to perform the
1738 inversion and redirection. */
1741 invert_jump_1 (rtx jump, rtx nlabel)
1745 ochanges = num_validated_changes ();
1746 invert_exp_1 (jump);
1747 if (num_validated_changes () == ochanges)
1750 return redirect_jump_1 (jump, nlabel);
1753 /* Invert the condition of the jump JUMP, and make it jump to label
1754 NLABEL instead of where it jumps now. Return true if successful. */
1757 invert_jump (rtx jump, rtx nlabel, int delete_unused)
1759 /* We have to either invert the condition and change the label or
1760 do neither. Either operation could fail. We first try to invert
1761 the jump. If that succeeds, we try changing the label. If that fails,
1762 we invert the jump back to what it was. */
1764 if (! invert_exp (jump))
1767 if (redirect_jump (jump, nlabel, delete_unused))
1769 /* Remove REG_EQUAL note if we have one. */
1770 rtx note = find_reg_note (jump, REG_EQUAL, NULL_RTX);
1772 remove_note (jump, note);
1774 invert_br_probabilities (jump);
1779 if (! invert_exp (jump))
1780 /* This should just be putting it back the way it was. */
1787 /* Like rtx_equal_p except that it considers two REGs as equal
1788 if they renumber to the same value and considers two commutative
1789 operations to be the same if the order of the operands has been
1792 ??? Addition is not commutative on the PA due to the weird implicit
1793 space register selection rules for memory addresses. Therefore, we
1794 don't consider a + b == b + a.
1796 We could/should make this test a little tighter. Possibly only
1797 disabling it on the PA via some backend macro or only disabling this
1798 case when the PLUS is inside a MEM. */
1801 rtx_renumbered_equal_p (rtx x, rtx y)
1804 enum rtx_code code = GET_CODE (x);
1810 if ((code == REG || (code == SUBREG && REG_P (SUBREG_REG (x))))
1811 && (REG_P (y) || (GET_CODE (y) == SUBREG
1812 && REG_P (SUBREG_REG (y)))))
1814 int reg_x = -1, reg_y = -1;
1815 int byte_x = 0, byte_y = 0;
1817 if (GET_MODE (x) != GET_MODE (y))
1820 /* If we haven't done any renumbering, don't
1821 make any assumptions. */
1822 if (reg_renumber == 0)
1823 return rtx_equal_p (x, y);
1827 reg_x = REGNO (SUBREG_REG (x));
1828 byte_x = SUBREG_BYTE (x);
1830 if (reg_renumber[reg_x] >= 0)
1832 reg_x = subreg_regno_offset (reg_renumber[reg_x],
1833 GET_MODE (SUBREG_REG (x)),
1842 if (reg_renumber[reg_x] >= 0)
1843 reg_x = reg_renumber[reg_x];
1846 if (GET_CODE (y) == SUBREG)
1848 reg_y = REGNO (SUBREG_REG (y));
1849 byte_y = SUBREG_BYTE (y);
1851 if (reg_renumber[reg_y] >= 0)
1853 reg_y = subreg_regno_offset (reg_renumber[reg_y],
1854 GET_MODE (SUBREG_REG (y)),
1863 if (reg_renumber[reg_y] >= 0)
1864 reg_y = reg_renumber[reg_y];
1867 return reg_x >= 0 && reg_x == reg_y && byte_x == byte_y;
1870 /* Now we have disposed of all the cases
1871 in which different rtx codes can match. */
1872 if (code != GET_CODE (y))
1885 /* We can't assume nonlocal labels have their following insns yet. */
1886 if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
1887 return XEXP (x, 0) == XEXP (y, 0);
1889 /* Two label-refs are equivalent if they point at labels
1890 in the same position in the instruction stream. */
1891 return (next_real_insn (XEXP (x, 0))
1892 == next_real_insn (XEXP (y, 0)));
1895 return XSTR (x, 0) == XSTR (y, 0);
1898 /* If we didn't match EQ equality above, they aren't the same. */
1905 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1907 if (GET_MODE (x) != GET_MODE (y))
1910 /* For commutative operations, the RTX match if the operand match in any
1911 order. Also handle the simple binary and unary cases without a loop.
1913 ??? Don't consider PLUS a commutative operator; see comments above. */
1914 if (COMMUTATIVE_P (x) && code != PLUS)
1915 return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
1916 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
1917 || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
1918 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
1919 else if (NON_COMMUTATIVE_P (x))
1920 return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
1921 && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
1922 else if (UNARY_P (x))
1923 return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));
1925 /* Compare the elements. If any pair of corresponding elements
1926 fail to match, return 0 for the whole things. */
1928 fmt = GET_RTX_FORMAT (code);
1929 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1935 if (XWINT (x, i) != XWINT (y, i))
1940 if (XINT (x, i) != XINT (y, i))
1945 if (XTREE (x, i) != XTREE (y, i))
1950 if (strcmp (XSTR (x, i), XSTR (y, i)))
1955 if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
1960 if (XEXP (x, i) != XEXP (y, i))
1967 if (XVECLEN (x, i) != XVECLEN (y, i))
1969 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
1970 if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
1981 /* If X is a hard register or equivalent to one or a subregister of one,
1982 return the hard register number. If X is a pseudo register that was not
1983 assigned a hard register, return the pseudo register number. Otherwise,
1984 return -1. Any rtx is valid for X. */
1991 if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0)
1992 return reg_renumber[REGNO (x)];
1995 if (GET_CODE (x) == SUBREG)
1997 int base = true_regnum (SUBREG_REG (x));
1998 if (base >= 0 && base < FIRST_PSEUDO_REGISTER)
1999 return base + subreg_regno_offset (REGNO (SUBREG_REG (x)),
2000 GET_MODE (SUBREG_REG (x)),
2001 SUBREG_BYTE (x), GET_MODE (x));
2006 /* Return regno of the register REG and handle subregs too. */
2008 reg_or_subregno (rtx reg)
2012 if (GET_CODE (reg) == SUBREG)
2013 return REGNO (SUBREG_REG (reg));