1 /* Move registers around to reduce number of move instructions needed.
2 Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 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
23 /* This module looks for cases where matching constraints would force
24 an instruction to need a reload, and this reload would be a register
25 to register move. It then attempts to change the registers used by the
26 instruction to avoid the move instruction. */
30 #include "coretypes.h"
32 #include "rtl.h" /* stdio.h must precede rtl.h for FFS. */
34 #include "insn-config.h"
38 #include "hard-reg-set.h"
42 #include "basic-block.h"
48 /* Turn STACK_GROWS_DOWNWARD into a boolean. */
49 #ifdef STACK_GROWS_DOWNWARD
50 #undef STACK_GROWS_DOWNWARD
51 #define STACK_GROWS_DOWNWARD 1
53 #define STACK_GROWS_DOWNWARD 0
56 static int perhaps_ends_bb_p (rtx);
57 static int optimize_reg_copy_1 (rtx, rtx, rtx);
58 static void optimize_reg_copy_2 (rtx, rtx, rtx);
59 static void optimize_reg_copy_3 (rtx, rtx, rtx);
60 static void copy_src_to_dest (rtx, rtx, rtx, int);
61 static int *regmove_bb_head;
64 int with[MAX_RECOG_OPERANDS];
65 enum { READ, WRITE, READWRITE } use[MAX_RECOG_OPERANDS];
66 int commutative[MAX_RECOG_OPERANDS];
67 int early_clobber[MAX_RECOG_OPERANDS];
70 static rtx discover_flags_reg (void);
71 static void mark_flags_life_zones (rtx);
72 static void flags_set_1 (rtx, rtx, void *);
74 static int try_auto_increment (rtx, rtx, rtx, rtx, HOST_WIDE_INT, int);
75 static int find_matches (rtx, struct match *);
76 static void replace_in_call_usage (rtx *, unsigned int, rtx, rtx);
77 static int fixup_match_1 (rtx, rtx, rtx, rtx, rtx, int, int, int, FILE *);
78 static int reg_is_remote_constant_p (rtx, rtx, rtx);
79 static int stable_and_no_regs_but_for_p (rtx, rtx, rtx);
80 static int regclass_compatible_p (int, int);
81 static int replacement_quality (rtx);
82 static int fixup_match_2 (rtx, rtx, rtx, rtx, FILE *);
84 /* Return nonzero if registers with CLASS1 and CLASS2 can be merged without
85 causing too much register allocation problems. */
87 regclass_compatible_p (int class0, int class1)
89 return (class0 == class1
90 || (reg_class_subset_p (class0, class1)
91 && ! CLASS_LIKELY_SPILLED_P (class0))
92 || (reg_class_subset_p (class1, class0)
93 && ! CLASS_LIKELY_SPILLED_P (class1)));
96 /* INC_INSN is an instruction that adds INCREMENT to REG.
97 Try to fold INC_INSN as a post/pre in/decrement into INSN.
98 Iff INC_INSN_SET is nonzero, inc_insn has a destination different from src.
99 Return nonzero for success. */
101 try_auto_increment (rtx insn, rtx inc_insn, rtx inc_insn_set, rtx reg,
102 HOST_WIDE_INT increment, int pre)
104 enum rtx_code inc_code;
106 rtx pset = single_set (insn);
109 /* Can't use the size of SET_SRC, we might have something like
110 (sign_extend:SI (mem:QI ... */
111 rtx use = find_use_as_address (pset, reg, 0);
112 if (use != 0 && use != (rtx) (size_t) 1)
114 int size = GET_MODE_SIZE (GET_MODE (use));
116 || (HAVE_POST_INCREMENT
117 && pre == 0 && (inc_code = POST_INC, increment == size))
118 || (HAVE_PRE_INCREMENT
119 && pre == 1 && (inc_code = PRE_INC, increment == size))
120 || (HAVE_POST_DECREMENT
121 && pre == 0 && (inc_code = POST_DEC, increment == -size))
122 || (HAVE_PRE_DECREMENT
123 && pre == 1 && (inc_code = PRE_DEC, increment == -size))
129 &SET_SRC (inc_insn_set),
130 XEXP (SET_SRC (inc_insn_set), 0), 1);
131 validate_change (insn, &XEXP (use, 0),
132 gen_rtx_fmt_e (inc_code, Pmode, reg), 1);
133 if (apply_change_group ())
135 /* If there is a REG_DEAD note on this insn, we must
136 change this not to REG_UNUSED meaning that the register
137 is set, but the value is dead. Failure to do so will
138 result in a sched1 abort -- when it recomputes lifetime
139 information, the number of REG_DEAD notes will have
141 rtx note = find_reg_note (insn, REG_DEAD, reg);
143 PUT_MODE (note, REG_UNUSED);
146 = gen_rtx_EXPR_LIST (REG_INC,
147 reg, REG_NOTES (insn));
149 delete_insn (inc_insn);
158 /* Determine if the pattern generated by add_optab has a clobber,
159 such as might be issued for a flags hard register. To make the
160 code elsewhere simpler, we handle cc0 in this same framework.
162 Return the register if one was discovered. Return NULL_RTX if
163 if no flags were found. Return pc_rtx if we got confused. */
166 discover_flags_reg (void)
169 tmp = gen_rtx_REG (word_mode, 10000);
170 tmp = gen_add3_insn (tmp, tmp, const2_rtx);
172 /* If we get something that isn't a simple set, or a
173 [(set ..) (clobber ..)], this whole function will go wrong. */
174 if (GET_CODE (tmp) == SET)
176 else if (GET_CODE (tmp) == PARALLEL)
180 if (XVECLEN (tmp, 0) != 2)
182 tmp = XVECEXP (tmp, 0, 1);
183 if (GET_CODE (tmp) != CLOBBER)
187 /* Don't do anything foolish if the md wanted to clobber a
188 scratch or something. We only care about hard regs.
189 Moreover we don't like the notion of subregs of hard regs. */
190 if (GET_CODE (tmp) == SUBREG
191 && REG_P (SUBREG_REG (tmp))
192 && REGNO (SUBREG_REG (tmp)) < FIRST_PSEUDO_REGISTER)
194 found = (REG_P (tmp) && REGNO (tmp) < FIRST_PSEUDO_REGISTER);
196 return (found ? tmp : NULL_RTX);
202 /* It is a tedious task identifying when the flags register is live and
203 when it is safe to optimize. Since we process the instruction stream
204 multiple times, locate and record these live zones by marking the
205 mode of the instructions --
207 QImode is used on the instruction at which the flags becomes live.
209 HImode is used within the range (exclusive) that the flags are
210 live. Thus the user of the flags is not marked.
212 All other instructions are cleared to VOIDmode. */
214 /* Used to communicate with flags_set_1. */
215 static rtx flags_set_1_rtx;
216 static int flags_set_1_set;
219 mark_flags_life_zones (rtx flags)
226 /* If we found a flags register on a cc0 host, bail. */
227 if (flags == NULL_RTX)
229 else if (flags != cc0_rtx)
233 /* Simple cases first: if no flags, clear all modes. If confusing,
234 mark the entire function as being in a flags shadow. */
235 if (flags == NULL_RTX || flags == pc_rtx)
237 enum machine_mode mode = (flags ? HImode : VOIDmode);
239 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
240 PUT_MODE (insn, mode);
248 flags_regno = REGNO (flags);
249 flags_nregs = hard_regno_nregs[flags_regno][GET_MODE (flags)];
251 flags_set_1_rtx = flags;
253 /* Process each basic block. */
254 FOR_EACH_BB_REVERSE (block)
259 insn = BB_HEAD (block);
260 end = BB_END (block);
262 /* Look out for the (unlikely) case of flags being live across
263 basic block boundaries. */
268 for (i = 0; i < flags_nregs; ++i)
269 live |= REGNO_REG_SET_P (block->global_live_at_start,
276 /* Process liveness in reverse order of importance --
277 alive, death, birth. This lets more important info
278 overwrite the mode of lesser info. */
283 /* In the cc0 case, death is not marked in reg notes,
284 but is instead the mere use of cc0 when it is alive. */
285 if (live && reg_mentioned_p (cc0_rtx, PATTERN (insn)))
288 /* In the hard reg case, we watch death notes. */
289 if (live && find_regno_note (insn, REG_DEAD, flags_regno))
292 PUT_MODE (insn, (live ? HImode : VOIDmode));
294 /* In either case, birth is denoted simply by its presence
295 as the destination of a set. */
297 note_stores (PATTERN (insn), flags_set_1, NULL);
301 PUT_MODE (insn, QImode);
305 PUT_MODE (insn, (live ? HImode : VOIDmode));
309 insn = NEXT_INSN (insn);
314 /* A subroutine of mark_flags_life_zones, called through note_stores. */
317 flags_set_1 (rtx x, rtx pat, void *data ATTRIBUTE_UNUSED)
319 if (GET_CODE (pat) == SET
320 && reg_overlap_mentioned_p (x, flags_set_1_rtx))
324 static int *regno_src_regno;
326 /* Indicate how good a choice REG (which appears as a source) is to replace
327 a destination register with. The higher the returned value, the better
328 the choice. The main objective is to avoid using a register that is
329 a candidate for tying to a hard register, since the output might in
330 turn be a candidate to be tied to a different hard register. */
332 replacement_quality (rtx reg)
336 /* Bad if this isn't a register at all. */
340 /* If this register is not meant to get a hard register,
341 it is a poor choice. */
342 if (REG_LIVE_LENGTH (REGNO (reg)) < 0)
345 src_regno = regno_src_regno[REGNO (reg)];
347 /* If it was not copied from another register, it is fine. */
351 /* Copied from a hard register? */
352 if (src_regno < FIRST_PSEUDO_REGISTER)
355 /* Copied from a pseudo register - not as bad as from a hard register,
356 yet still cumbersome, since the register live length will be lengthened
357 when the registers get tied. */
361 /* Return 1 if INSN might end a basic block. */
363 static int perhaps_ends_bb_p (rtx insn)
365 switch (GET_CODE (insn))
369 /* These always end a basic block. */
373 /* A CALL_INSN might be the last insn of a basic block, if it is inside
374 an EH region or if there are nonlocal gotos. Note that this test is
375 very conservative. */
376 if (nonlocal_goto_handler_labels)
380 return can_throw_internal (insn);
384 /* INSN is a copy from SRC to DEST, both registers, and SRC does not die
387 Search forward to see if SRC dies before either it or DEST is modified,
388 but don't scan past the end of a basic block. If so, we can replace SRC
389 with DEST and let SRC die in INSN.
391 This will reduce the number of registers live in that range and may enable
392 DEST to be tied to SRC, thus often saving one register in addition to a
393 register-register copy. */
396 optimize_reg_copy_1 (rtx insn, rtx dest, rtx src)
401 int sregno = REGNO (src);
402 int dregno = REGNO (dest);
404 /* We don't want to mess with hard regs if register classes are small. */
406 || (SMALL_REGISTER_CLASSES
407 && (sregno < FIRST_PSEUDO_REGISTER
408 || dregno < FIRST_PSEUDO_REGISTER))
409 /* We don't see all updates to SP if they are in an auto-inc memory
410 reference, so we must disallow this optimization on them. */
411 || sregno == STACK_POINTER_REGNUM || dregno == STACK_POINTER_REGNUM)
414 for (p = NEXT_INSN (insn); p; p = NEXT_INSN (p))
416 /* ??? We can't scan past the end of a basic block without updating
417 the register lifetime info (REG_DEAD/basic_block_live_at_start). */
418 if (perhaps_ends_bb_p (p))
420 else if (! INSN_P (p))
423 if (reg_set_p (src, p) || reg_set_p (dest, p)
424 /* If SRC is an asm-declared register, it must not be replaced
425 in any asm. Unfortunately, the REG_EXPR tree for the asm
426 variable may be absent in the SRC rtx, so we can't check the
427 actual register declaration easily (the asm operand will have
428 it, though). To avoid complicating the test for a rare case,
429 we just don't perform register replacement for a hard reg
430 mentioned in an asm. */
431 || (sregno < FIRST_PSEUDO_REGISTER
432 && asm_noperands (PATTERN (p)) >= 0
433 && reg_overlap_mentioned_p (src, PATTERN (p)))
434 /* Don't change hard registers used by a call. */
435 || (CALL_P (p) && sregno < FIRST_PSEUDO_REGISTER
436 && find_reg_fusage (p, USE, src))
437 /* Don't change a USE of a register. */
438 || (GET_CODE (PATTERN (p)) == USE
439 && reg_overlap_mentioned_p (src, XEXP (PATTERN (p), 0))))
442 /* See if all of SRC dies in P. This test is slightly more
443 conservative than it needs to be. */
444 if ((note = find_regno_note (p, REG_DEAD, sregno)) != 0
445 && GET_MODE (XEXP (note, 0)) == GET_MODE (src))
453 /* We can do the optimization. Scan forward from INSN again,
454 replacing regs as we go. Set FAILED if a replacement can't
455 be done. In that case, we can't move the death note for SRC.
456 This should be rare. */
458 /* Set to stop at next insn. */
459 for (q = next_real_insn (insn);
460 q != next_real_insn (p);
461 q = next_real_insn (q))
463 if (reg_overlap_mentioned_p (src, PATTERN (q)))
465 /* If SRC is a hard register, we might miss some
466 overlapping registers with validate_replace_rtx,
467 so we would have to undo it. We can't if DEST is
468 present in the insn, so fail in that combination
470 if (sregno < FIRST_PSEUDO_REGISTER
471 && reg_mentioned_p (dest, PATTERN (q)))
474 /* Replace all uses and make sure that the register
475 isn't still present. */
476 else if (validate_replace_rtx (src, dest, q)
477 && (sregno >= FIRST_PSEUDO_REGISTER
478 || ! reg_overlap_mentioned_p (src,
483 validate_replace_rtx (dest, src, q);
488 /* For SREGNO, count the total number of insns scanned.
489 For DREGNO, count the total number of insns scanned after
490 passing the death note for DREGNO. */
495 /* If the insn in which SRC dies is a CALL_INSN, don't count it
496 as a call that has been crossed. Otherwise, count it. */
497 if (q != p && CALL_P (q))
499 /* Similarly, total calls for SREGNO, total calls beyond
500 the death note for DREGNO. */
506 /* If DEST dies here, remove the death note and save it for
507 later. Make sure ALL of DEST dies here; again, this is
508 overly conservative. */
510 && (dest_death = find_regno_note (q, REG_DEAD, dregno)) != 0)
512 if (GET_MODE (XEXP (dest_death, 0)) != GET_MODE (dest))
513 failed = 1, dest_death = 0;
515 remove_note (q, dest_death);
521 /* These counters need to be updated if and only if we are
522 going to move the REG_DEAD note. */
523 if (sregno >= FIRST_PSEUDO_REGISTER)
525 if (REG_LIVE_LENGTH (sregno) >= 0)
527 REG_LIVE_LENGTH (sregno) -= s_length;
528 /* REG_LIVE_LENGTH is only an approximation after
529 combine if sched is not run, so make sure that we
530 still have a reasonable value. */
531 if (REG_LIVE_LENGTH (sregno) < 2)
532 REG_LIVE_LENGTH (sregno) = 2;
535 REG_N_CALLS_CROSSED (sregno) -= s_n_calls;
538 /* Move death note of SRC from P to INSN. */
539 remove_note (p, note);
540 XEXP (note, 1) = REG_NOTES (insn);
541 REG_NOTES (insn) = note;
544 /* DEST is also dead if INSN has a REG_UNUSED note for DEST. */
546 && (dest_death = find_regno_note (insn, REG_UNUSED, dregno)))
548 PUT_REG_NOTE_KIND (dest_death, REG_DEAD);
549 remove_note (insn, dest_death);
552 /* Put death note of DEST on P if we saw it die. */
555 XEXP (dest_death, 1) = REG_NOTES (p);
556 REG_NOTES (p) = dest_death;
558 if (dregno >= FIRST_PSEUDO_REGISTER)
560 /* If and only if we are moving the death note for DREGNO,
561 then we need to update its counters. */
562 if (REG_LIVE_LENGTH (dregno) >= 0)
563 REG_LIVE_LENGTH (dregno) += d_length;
564 REG_N_CALLS_CROSSED (dregno) += d_n_calls;
571 /* If SRC is a hard register which is set or killed in some other
572 way, we can't do this optimization. */
573 else if (sregno < FIRST_PSEUDO_REGISTER
574 && dead_or_set_p (p, src))
580 /* INSN is a copy of SRC to DEST, in which SRC dies. See if we now have
581 a sequence of insns that modify DEST followed by an insn that sets
582 SRC to DEST in which DEST dies, with no prior modification of DEST.
583 (There is no need to check if the insns in between actually modify
584 DEST. We should not have cases where DEST is not modified, but
585 the optimization is safe if no such modification is detected.)
586 In that case, we can replace all uses of DEST, starting with INSN and
587 ending with the set of SRC to DEST, with SRC. We do not do this
588 optimization if a CALL_INSN is crossed unless SRC already crosses a
589 call or if DEST dies before the copy back to SRC.
591 It is assumed that DEST and SRC are pseudos; it is too complicated to do
592 this for hard registers since the substitutions we may make might fail. */
595 optimize_reg_copy_2 (rtx insn, rtx dest, rtx src)
599 int sregno = REGNO (src);
600 int dregno = REGNO (dest);
602 for (p = NEXT_INSN (insn); p; p = NEXT_INSN (p))
604 /* ??? We can't scan past the end of a basic block without updating
605 the register lifetime info (REG_DEAD/basic_block_live_at_start). */
606 if (perhaps_ends_bb_p (p))
608 else if (! INSN_P (p))
611 set = single_set (p);
612 if (set && SET_SRC (set) == dest && SET_DEST (set) == src
613 && find_reg_note (p, REG_DEAD, dest))
615 /* We can do the optimization. Scan forward from INSN again,
616 replacing regs as we go. */
618 /* Set to stop at next insn. */
619 for (q = insn; q != NEXT_INSN (p); q = NEXT_INSN (q))
622 if (reg_mentioned_p (dest, PATTERN (q)))
623 PATTERN (q) = replace_rtx (PATTERN (q), dest, src);
628 REG_N_CALLS_CROSSED (dregno)--;
629 REG_N_CALLS_CROSSED (sregno)++;
633 remove_note (p, find_reg_note (p, REG_DEAD, dest));
634 REG_N_DEATHS (dregno)--;
635 remove_note (insn, find_reg_note (insn, REG_DEAD, src));
636 REG_N_DEATHS (sregno)--;
640 if (reg_set_p (src, p)
641 || find_reg_note (p, REG_DEAD, dest)
642 || (CALL_P (p) && REG_N_CALLS_CROSSED (sregno) == 0))
646 /* INSN is a ZERO_EXTEND or SIGN_EXTEND of SRC to DEST.
647 Look if SRC dies there, and if it is only set once, by loading
648 it from memory. If so, try to incorporate the zero/sign extension
649 into the memory read, change SRC to the mode of DEST, and alter
650 the remaining accesses to use the appropriate SUBREG. This allows
651 SRC and DEST to be tied later. */
653 optimize_reg_copy_3 (rtx insn, rtx dest, rtx src)
655 rtx src_reg = XEXP (src, 0);
656 int src_no = REGNO (src_reg);
657 int dst_no = REGNO (dest);
659 enum machine_mode old_mode;
661 if (src_no < FIRST_PSEUDO_REGISTER
662 || dst_no < FIRST_PSEUDO_REGISTER
663 || ! find_reg_note (insn, REG_DEAD, src_reg)
664 || REG_N_DEATHS (src_no) != 1
665 || REG_N_SETS (src_no) != 1)
667 for (p = PREV_INSN (insn); p && ! reg_set_p (src_reg, p); p = PREV_INSN (p))
668 /* ??? We can't scan past the end of a basic block without updating
669 the register lifetime info (REG_DEAD/basic_block_live_at_start). */
670 if (perhaps_ends_bb_p (p))
676 if (! (set = single_set (p))
677 || !MEM_P (SET_SRC (set))
678 /* If there's a REG_EQUIV note, this must be an insn that loads an
679 argument. Prefer keeping the note over doing this optimization. */
680 || find_reg_note (p, REG_EQUIV, NULL_RTX)
681 || SET_DEST (set) != src_reg)
684 /* Be conservative: although this optimization is also valid for
685 volatile memory references, that could cause trouble in later passes. */
686 if (MEM_VOLATILE_P (SET_SRC (set)))
689 /* Do not use a SUBREG to truncate from one mode to another if truncation
691 if (GET_MODE_BITSIZE (GET_MODE (src_reg)) <= GET_MODE_BITSIZE (GET_MODE (src))
692 && !TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (GET_MODE (src)),
693 GET_MODE_BITSIZE (GET_MODE (src_reg))))
696 old_mode = GET_MODE (src_reg);
697 PUT_MODE (src_reg, GET_MODE (src));
698 XEXP (src, 0) = SET_SRC (set);
700 /* Include this change in the group so that it's easily undone if
701 one of the changes in the group is invalid. */
702 validate_change (p, &SET_SRC (set), src, 1);
704 /* Now walk forward making additional replacements. We want to be able
705 to undo all the changes if a later substitution fails. */
706 while (p = NEXT_INSN (p), p != insn)
711 /* Make a tentative change. */
712 validate_replace_rtx_group (src_reg,
713 gen_lowpart_SUBREG (old_mode, src_reg),
717 validate_replace_rtx_group (src, src_reg, insn);
719 /* Now see if all the changes are valid. */
720 if (! apply_change_group ())
722 /* One or more changes were no good. Back out everything. */
723 PUT_MODE (src_reg, old_mode);
724 XEXP (src, 0) = src_reg;
728 rtx note = find_reg_note (p, REG_EQUAL, NULL_RTX);
730 remove_note (p, note);
735 /* If we were not able to update the users of src to use dest directly, try
736 instead moving the value to dest directly before the operation. */
739 copy_src_to_dest (rtx insn, rtx src, rtx dest, int old_max_uid)
754 /* A REG_LIVE_LENGTH of -1 indicates the register is equivalent to a constant
755 or memory location and is used infrequently; a REG_LIVE_LENGTH of -2 is
756 parameter when there is no frame pointer that is not allocated a register.
757 For now, we just reject them, rather than incrementing the live length. */
760 && REG_LIVE_LENGTH (REGNO (src)) > 0
762 && REG_LIVE_LENGTH (REGNO (dest)) > 0
763 && (set = single_set (insn)) != NULL_RTX
764 && !reg_mentioned_p (dest, SET_SRC (set))
765 && GET_MODE (src) == GET_MODE (dest))
767 int old_num_regs = reg_rtx_no;
769 /* Generate the src->dest move. */
771 emit_move_insn (dest, src);
774 /* If this sequence uses new registers, we may not use it. */
775 if (old_num_regs != reg_rtx_no
776 || ! validate_replace_rtx (src, dest, insn))
778 /* We have to restore reg_rtx_no to its old value, lest
779 recompute_reg_usage will try to compute the usage of the
780 new regs, yet reg_n_info is not valid for them. */
781 reg_rtx_no = old_num_regs;
784 emit_insn_before (seq, insn);
785 move_insn = PREV_INSN (insn);
786 p_move_notes = ®_NOTES (move_insn);
787 p_insn_notes = ®_NOTES (insn);
789 /* Move any notes mentioning src to the move instruction. */
790 for (link = REG_NOTES (insn); link != NULL_RTX; link = next)
792 next = XEXP (link, 1);
793 if (XEXP (link, 0) == src)
795 *p_move_notes = link;
796 p_move_notes = &XEXP (link, 1);
800 *p_insn_notes = link;
801 p_insn_notes = &XEXP (link, 1);
805 *p_move_notes = NULL_RTX;
806 *p_insn_notes = NULL_RTX;
808 /* Is the insn the head of a basic block? If so extend it. */
809 insn_uid = INSN_UID (insn);
810 move_uid = INSN_UID (move_insn);
811 if (insn_uid < old_max_uid)
813 bb = regmove_bb_head[insn_uid];
816 BB_HEAD (BASIC_BLOCK (bb)) = move_insn;
817 regmove_bb_head[insn_uid] = -1;
821 /* Update the various register tables. */
822 dest_regno = REGNO (dest);
823 REG_N_SETS (dest_regno) ++;
824 REG_LIVE_LENGTH (dest_regno)++;
825 if (REGNO_FIRST_UID (dest_regno) == insn_uid)
826 REGNO_FIRST_UID (dest_regno) = move_uid;
828 src_regno = REGNO (src);
829 if (! find_reg_note (move_insn, REG_DEAD, src))
830 REG_LIVE_LENGTH (src_regno)++;
832 if (REGNO_FIRST_UID (src_regno) == insn_uid)
833 REGNO_FIRST_UID (src_regno) = move_uid;
835 if (REGNO_LAST_UID (src_regno) == insn_uid)
836 REGNO_LAST_UID (src_regno) = move_uid;
841 /* Return whether REG is set in only one location, and is set to a
842 constant, but is set in a different basic block from INSN (an
843 instructions which uses REG). In this case REG is equivalent to a
844 constant, and we don't want to break that equivalence, because that
845 may increase register pressure and make reload harder. If REG is
846 set in the same basic block as INSN, we don't worry about it,
847 because we'll probably need a register anyhow (??? but what if REG
848 is used in a different basic block as well as this one?). FIRST is
849 the first insn in the function. */
852 reg_is_remote_constant_p (rtx reg, rtx insn, rtx first)
856 if (REG_N_SETS (REGNO (reg)) != 1)
859 /* Look for the set. */
860 for (p = LOG_LINKS (insn); p; p = XEXP (p, 1))
864 if (REG_NOTE_KIND (p) != 0)
866 s = single_set (XEXP (p, 0));
868 && REG_P (SET_DEST (s))
869 && REGNO (SET_DEST (s)) == REGNO (reg))
871 /* The register is set in the same basic block. */
876 for (p = first; p && p != insn; p = NEXT_INSN (p))
884 && REG_P (SET_DEST (s))
885 && REGNO (SET_DEST (s)) == REGNO (reg))
887 /* This is the instruction which sets REG. If there is a
888 REG_EQUAL note, then REG is equivalent to a constant. */
889 if (find_reg_note (p, REG_EQUAL, NULL_RTX))
898 /* INSN is adding a CONST_INT to a REG. We search backwards looking for
899 another add immediate instruction with the same source and dest registers,
900 and if we find one, we change INSN to an increment, and return 1. If
901 no changes are made, we return 0.
904 (set (reg100) (plus reg1 offset1))
906 (set (reg100) (plus reg1 offset2))
908 (set (reg100) (plus reg1 offset1))
910 (set (reg100) (plus reg100 offset2-offset1)) */
912 /* ??? What does this comment mean? */
913 /* cse disrupts preincrement / postdecrement sequences when it finds a
914 hard register as ultimate source, like the frame pointer. */
917 fixup_match_2 (rtx insn, rtx dst, rtx src, rtx offset, FILE *regmove_dump_file)
919 rtx p, dst_death = 0;
920 int length, num_calls = 0;
922 /* If SRC dies in INSN, we'd have to move the death note. This is
923 considered to be very unlikely, so we just skip the optimization
925 if (find_regno_note (insn, REG_DEAD, REGNO (src)))
928 /* Scan backward to find the first instruction that sets DST. */
930 for (length = 0, p = PREV_INSN (insn); p; p = PREV_INSN (p))
934 /* ??? We can't scan past the end of a basic block without updating
935 the register lifetime info (REG_DEAD/basic_block_live_at_start). */
936 if (perhaps_ends_bb_p (p))
938 else if (! INSN_P (p))
941 if (find_regno_note (p, REG_DEAD, REGNO (dst)))
946 pset = single_set (p);
947 if (pset && SET_DEST (pset) == dst
948 && GET_CODE (SET_SRC (pset)) == PLUS
949 && XEXP (SET_SRC (pset), 0) == src
950 && GET_CODE (XEXP (SET_SRC (pset), 1)) == CONST_INT)
952 HOST_WIDE_INT newconst
953 = INTVAL (offset) - INTVAL (XEXP (SET_SRC (pset), 1));
954 rtx add = gen_add3_insn (dst, dst, GEN_INT (newconst));
956 if (add && validate_change (insn, &PATTERN (insn), add, 0))
958 /* Remove the death note for DST from DST_DEATH. */
961 remove_death (REGNO (dst), dst_death);
962 REG_LIVE_LENGTH (REGNO (dst)) += length;
963 REG_N_CALLS_CROSSED (REGNO (dst)) += num_calls;
966 if (regmove_dump_file)
967 fprintf (regmove_dump_file,
968 "Fixed operand of insn %d.\n",
972 for (p = PREV_INSN (insn); p; p = PREV_INSN (p))
979 if (reg_overlap_mentioned_p (dst, PATTERN (p)))
981 if (try_auto_increment (p, insn, 0, dst, newconst, 0))
986 for (p = NEXT_INSN (insn); p; p = NEXT_INSN (p))
993 if (reg_overlap_mentioned_p (dst, PATTERN (p)))
995 try_auto_increment (p, insn, 0, dst, newconst, 1);
1004 if (reg_set_p (dst, PATTERN (p)))
1007 /* If we have passed a call instruction, and the
1008 pseudo-reg SRC is not already live across a call,
1009 then don't perform the optimization. */
1010 /* reg_set_p is overly conservative for CALL_INSNS, thinks that all
1011 hard regs are clobbered. Thus, we only use it for src for
1018 if (REG_N_CALLS_CROSSED (REGNO (src)) == 0)
1021 if (call_used_regs [REGNO (dst)]
1022 || find_reg_fusage (p, CLOBBER, dst))
1025 else if (reg_set_p (src, PATTERN (p)))
1032 /* Main entry for the register move optimization.
1033 F is the first instruction.
1034 NREGS is one plus the highest pseudo-reg number used in the instruction.
1035 REGMOVE_DUMP_FILE is a stream for output of a trace of actions taken
1036 (or 0 if none should be output). */
1039 regmove_optimize (rtx f, int nregs, FILE *regmove_dump_file)
1041 int old_max_uid = get_max_uid ();
1046 rtx copy_src, copy_dst;
1049 /* ??? Hack. Regmove doesn't examine the CFG, and gets mightily
1050 confused by non-call exceptions ending blocks. */
1051 if (flag_non_call_exceptions)
1054 /* Find out where a potential flags register is live, and so that we
1055 can suppress some optimizations in those zones. */
1056 mark_flags_life_zones (discover_flags_reg ());
1058 regno_src_regno = xmalloc (sizeof *regno_src_regno * nregs);
1059 for (i = nregs; --i >= 0; ) regno_src_regno[i] = -1;
1061 regmove_bb_head = xmalloc (sizeof (int) * (old_max_uid + 1));
1062 for (i = old_max_uid; i >= 0; i--) regmove_bb_head[i] = -1;
1064 regmove_bb_head[INSN_UID (BB_HEAD (bb))] = bb->index;
1066 /* A forward/backward pass. Replace output operands with input operands. */
1068 for (pass = 0; pass <= 2; pass++)
1070 if (! flag_regmove && pass >= flag_expensive_optimizations)
1073 if (regmove_dump_file)
1074 fprintf (regmove_dump_file, "Starting %s pass...\n",
1075 pass ? "backward" : "forward");
1077 for (insn = pass ? get_last_insn () : f; insn;
1078 insn = pass ? PREV_INSN (insn) : NEXT_INSN (insn))
1081 int op_no, match_no;
1083 set = single_set (insn);
1087 if (flag_expensive_optimizations && ! pass
1088 && (GET_CODE (SET_SRC (set)) == SIGN_EXTEND
1089 || GET_CODE (SET_SRC (set)) == ZERO_EXTEND)
1090 && REG_P (XEXP (SET_SRC (set), 0))
1091 && REG_P (SET_DEST (set)))
1092 optimize_reg_copy_3 (insn, SET_DEST (set), SET_SRC (set));
1094 if (flag_expensive_optimizations && ! pass
1095 && REG_P (SET_SRC (set))
1096 && REG_P (SET_DEST (set)))
1098 /* If this is a register-register copy where SRC is not dead,
1099 see if we can optimize it. If this optimization succeeds,
1100 it will become a copy where SRC is dead. */
1101 if ((find_reg_note (insn, REG_DEAD, SET_SRC (set))
1102 || optimize_reg_copy_1 (insn, SET_DEST (set), SET_SRC (set)))
1103 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
1105 /* Similarly for a pseudo-pseudo copy when SRC is dead. */
1106 if (REGNO (SET_SRC (set)) >= FIRST_PSEUDO_REGISTER)
1107 optimize_reg_copy_2 (insn, SET_DEST (set), SET_SRC (set));
1108 if (regno_src_regno[REGNO (SET_DEST (set))] < 0
1109 && SET_SRC (set) != SET_DEST (set))
1111 int srcregno = REGNO (SET_SRC (set));
1112 if (regno_src_regno[srcregno] >= 0)
1113 srcregno = regno_src_regno[srcregno];
1114 regno_src_regno[REGNO (SET_DEST (set))] = srcregno;
1121 if (! find_matches (insn, &match))
1124 /* Now scan through the operands looking for a source operand
1125 which is supposed to match the destination operand.
1126 Then scan forward for an instruction which uses the dest
1128 If it dies there, then replace the dest in both operands with
1129 the source operand. */
1131 for (op_no = 0; op_no < recog_data.n_operands; op_no++)
1133 rtx src, dst, src_subreg;
1134 enum reg_class src_class, dst_class;
1136 match_no = match.with[op_no];
1138 /* Nothing to do if the two operands aren't supposed to match. */
1142 src = recog_data.operand[op_no];
1143 dst = recog_data.operand[match_no];
1149 if (GET_CODE (dst) == SUBREG
1150 && GET_MODE_SIZE (GET_MODE (dst))
1151 >= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dst))))
1154 = gen_rtx_SUBREG (GET_MODE (SUBREG_REG (dst)),
1155 src, SUBREG_BYTE (dst));
1156 dst = SUBREG_REG (dst);
1159 || REGNO (dst) < FIRST_PSEUDO_REGISTER)
1162 if (REGNO (src) < FIRST_PSEUDO_REGISTER)
1164 if (match.commutative[op_no] < op_no)
1165 regno_src_regno[REGNO (dst)] = REGNO (src);
1169 if (REG_LIVE_LENGTH (REGNO (src)) < 0)
1172 /* op_no/src must be a read-only operand, and
1173 match_operand/dst must be a write-only operand. */
1174 if (match.use[op_no] != READ
1175 || match.use[match_no] != WRITE)
1178 if (match.early_clobber[match_no]
1179 && count_occurrences (PATTERN (insn), src, 0) > 1)
1182 /* Make sure match_operand is the destination. */
1183 if (recog_data.operand[match_no] != SET_DEST (set))
1186 /* If the operands already match, then there is nothing to do. */
1187 if (operands_match_p (src, dst))
1190 /* But in the commutative case, we might find a better match. */
1191 if (match.commutative[op_no] >= 0)
1193 rtx comm = recog_data.operand[match.commutative[op_no]];
1194 if (operands_match_p (comm, dst)
1195 && (replacement_quality (comm)
1196 >= replacement_quality (src)))
1200 src_class = reg_preferred_class (REGNO (src));
1201 dst_class = reg_preferred_class (REGNO (dst));
1202 if (! regclass_compatible_p (src_class, dst_class))
1205 if (GET_MODE (src) != GET_MODE (dst))
1208 if (fixup_match_1 (insn, set, src, src_subreg, dst, pass,
1216 /* A backward pass. Replace input operands with output operands. */
1218 if (regmove_dump_file)
1219 fprintf (regmove_dump_file, "Starting backward pass...\n");
1221 for (insn = get_last_insn (); insn; insn = PREV_INSN (insn))
1225 int op_no, match_no;
1228 if (! find_matches (insn, &match))
1231 /* Now scan through the operands looking for a destination operand
1232 which is supposed to match a source operand.
1233 Then scan backward for an instruction which sets the source
1234 operand. If safe, then replace the source operand with the
1235 dest operand in both instructions. */
1237 copy_src = NULL_RTX;
1238 copy_dst = NULL_RTX;
1239 for (op_no = 0; op_no < recog_data.n_operands; op_no++)
1241 rtx set, p, src, dst;
1242 rtx src_note, dst_note;
1244 enum reg_class src_class, dst_class;
1247 match_no = match.with[op_no];
1249 /* Nothing to do if the two operands aren't supposed to match. */
1253 dst = recog_data.operand[match_no];
1254 src = recog_data.operand[op_no];
1260 || REGNO (dst) < FIRST_PSEUDO_REGISTER
1261 || REG_LIVE_LENGTH (REGNO (dst)) < 0
1262 || GET_MODE (src) != GET_MODE (dst))
1265 /* If the operands already match, then there is nothing to do. */
1266 if (operands_match_p (src, dst))
1269 if (match.commutative[op_no] >= 0)
1271 rtx comm = recog_data.operand[match.commutative[op_no]];
1272 if (operands_match_p (comm, dst))
1276 set = single_set (insn);
1280 /* Note that single_set ignores parts of a parallel set for
1281 which one of the destinations is REG_UNUSED. We can't
1282 handle that here, since we can wind up rewriting things
1283 such that a single register is set twice within a single
1285 if (reg_set_p (src, insn))
1288 /* match_no/dst must be a write-only operand, and
1289 operand_operand/src must be a read-only operand. */
1290 if (match.use[op_no] != READ
1291 || match.use[match_no] != WRITE)
1294 if (match.early_clobber[match_no]
1295 && count_occurrences (PATTERN (insn), src, 0) > 1)
1298 /* Make sure match_no is the destination. */
1299 if (recog_data.operand[match_no] != SET_DEST (set))
1302 if (REGNO (src) < FIRST_PSEUDO_REGISTER)
1304 if (GET_CODE (SET_SRC (set)) == PLUS
1305 && GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT
1306 && XEXP (SET_SRC (set), 0) == src
1307 && fixup_match_2 (insn, dst, src,
1308 XEXP (SET_SRC (set), 1),
1313 src_class = reg_preferred_class (REGNO (src));
1314 dst_class = reg_preferred_class (REGNO (dst));
1316 if (! (src_note = find_reg_note (insn, REG_DEAD, src)))
1318 /* We used to force the copy here like in other cases, but
1319 it produces worse code, as it eliminates no copy
1320 instructions and the copy emitted will be produced by
1321 reload anyway. On patterns with multiple alternatives,
1322 there may be better solution available.
1324 In particular this change produced slower code for numeric
1330 if (! regclass_compatible_p (src_class, dst_class))
1340 /* Can not modify an earlier insn to set dst if this insn
1341 uses an old value in the source. */
1342 if (reg_overlap_mentioned_p (dst, SET_SRC (set)))
1352 /* If src is set once in a different basic block,
1353 and is set equal to a constant, then do not use
1354 it for this optimization, as this would make it
1355 no longer equivalent to a constant. */
1357 if (reg_is_remote_constant_p (src, insn, f))
1368 if (regmove_dump_file)
1369 fprintf (regmove_dump_file,
1370 "Could fix operand %d of insn %d matching operand %d.\n",
1371 op_no, INSN_UID (insn), match_no);
1373 /* Scan backward to find the first instruction that uses
1374 the input operand. If the operand is set here, then
1375 replace it in both instructions with match_no. */
1377 for (length = 0, p = PREV_INSN (insn); p; p = PREV_INSN (p))
1381 /* ??? We can't scan past the end of a basic block without
1382 updating the register lifetime info
1383 (REG_DEAD/basic_block_live_at_start). */
1384 if (perhaps_ends_bb_p (p))
1386 else if (! INSN_P (p))
1391 /* ??? See if all of SRC is set in P. This test is much
1392 more conservative than it needs to be. */
1393 pset = single_set (p);
1394 if (pset && SET_DEST (pset) == src)
1396 /* We use validate_replace_rtx, in case there
1397 are multiple identical source operands. All of
1398 them have to be changed at the same time. */
1399 if (validate_replace_rtx (src, dst, insn))
1401 if (validate_change (p, &SET_DEST (pset),
1406 /* Change all source operands back.
1407 This modifies the dst as a side-effect. */
1408 validate_replace_rtx (dst, src, insn);
1409 /* Now make sure the dst is right. */
1410 validate_change (insn,
1411 recog_data.operand_loc[match_no],
1418 if (reg_overlap_mentioned_p (src, PATTERN (p))
1419 || reg_overlap_mentioned_p (dst, PATTERN (p)))
1422 /* If we have passed a call instruction, and the
1423 pseudo-reg DST is not already live across a call,
1424 then don't perform the optimization. */
1429 if (REG_N_CALLS_CROSSED (REGNO (dst)) == 0)
1438 /* Remove the death note for SRC from INSN. */
1439 remove_note (insn, src_note);
1440 /* Move the death note for SRC to P if it is used
1442 if (reg_overlap_mentioned_p (src, PATTERN (p)))
1444 XEXP (src_note, 1) = REG_NOTES (p);
1445 REG_NOTES (p) = src_note;
1447 /* If there is a REG_DEAD note for DST on P, then remove
1448 it, because DST is now set there. */
1449 if ((dst_note = find_reg_note (p, REG_DEAD, dst)))
1450 remove_note (p, dst_note);
1452 dstno = REGNO (dst);
1453 srcno = REGNO (src);
1455 REG_N_SETS (dstno)++;
1456 REG_N_SETS (srcno)--;
1458 REG_N_CALLS_CROSSED (dstno) += num_calls;
1459 REG_N_CALLS_CROSSED (srcno) -= num_calls;
1461 REG_LIVE_LENGTH (dstno) += length;
1462 if (REG_LIVE_LENGTH (srcno) >= 0)
1464 REG_LIVE_LENGTH (srcno) -= length;
1465 /* REG_LIVE_LENGTH is only an approximation after
1466 combine if sched is not run, so make sure that we
1467 still have a reasonable value. */
1468 if (REG_LIVE_LENGTH (srcno) < 2)
1469 REG_LIVE_LENGTH (srcno) = 2;
1472 if (regmove_dump_file)
1473 fprintf (regmove_dump_file,
1474 "Fixed operand %d of insn %d matching operand %d.\n",
1475 op_no, INSN_UID (insn), match_no);
1481 /* If we weren't able to replace any of the alternatives, try an
1482 alternative approach of copying the source to the destination. */
1483 if (!success && copy_src != NULL_RTX)
1484 copy_src_to_dest (insn, copy_src, copy_dst, old_max_uid);
1489 /* In fixup_match_1, some insns may have been inserted after basic block
1490 ends. Fix that here. */
1493 rtx end = BB_END (bb);
1495 rtx next = NEXT_INSN (new);
1496 while (next != 0 && INSN_UID (next) >= old_max_uid
1497 && (bb->next_bb == EXIT_BLOCK_PTR || BB_HEAD (bb->next_bb) != next))
1498 new = next, next = NEXT_INSN (new);
1504 free (regno_src_regno);
1505 free (regmove_bb_head);
1508 /* Returns nonzero if INSN's pattern has matching constraints for any operand.
1509 Returns 0 if INSN can't be recognized, or if the alternative can't be
1512 Initialize the info in MATCHP based on the constraints. */
1515 find_matches (rtx insn, struct match *matchp)
1517 int likely_spilled[MAX_RECOG_OPERANDS];
1519 int any_matches = 0;
1521 extract_insn (insn);
1522 if (! constrain_operands (0))
1525 /* Must initialize this before main loop, because the code for
1526 the commutative case may set matches for operands other than
1528 for (op_no = recog_data.n_operands; --op_no >= 0; )
1529 matchp->with[op_no] = matchp->commutative[op_no] = -1;
1531 for (op_no = 0; op_no < recog_data.n_operands; op_no++)
1537 p = recog_data.constraints[op_no];
1539 likely_spilled[op_no] = 0;
1540 matchp->use[op_no] = READ;
1541 matchp->early_clobber[op_no] = 0;
1543 matchp->use[op_no] = WRITE;
1545 matchp->use[op_no] = READWRITE;
1547 for (;*p && i < which_alternative; p++)
1551 while ((c = *p) != '\0' && c != ',')
1560 matchp->early_clobber[op_no] = 1;
1563 matchp->commutative[op_no] = op_no + 1;
1564 matchp->commutative[op_no + 1] = op_no;
1567 case '0': case '1': case '2': case '3': case '4':
1568 case '5': case '6': case '7': case '8': case '9':
1571 unsigned long match_ul = strtoul (p, &end, 10);
1572 int match = match_ul;
1576 if (match < op_no && likely_spilled[match])
1578 matchp->with[op_no] = match;
1580 if (matchp->commutative[op_no] >= 0)
1581 matchp->with[matchp->commutative[op_no]] = match;
1585 case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'h':
1586 case 'j': case 'k': case 'l': case 'p': case 'q': case 't': case 'u':
1587 case 'v': case 'w': case 'x': case 'y': case 'z': case 'A': case 'B':
1588 case 'C': case 'D': case 'W': case 'Y': case 'Z':
1589 if (CLASS_LIKELY_SPILLED_P (REG_CLASS_FROM_CONSTRAINT ((unsigned char) c, p) ))
1590 likely_spilled[op_no] = 1;
1593 p += CONSTRAINT_LEN (c, p);
1599 /* Try to replace all occurrences of DST_REG with SRC in LOC, that is
1600 assumed to be in INSN. */
1603 replace_in_call_usage (rtx *loc, unsigned int dst_reg, rtx src, rtx insn)
1613 code = GET_CODE (x);
1616 if (REGNO (x) != dst_reg)
1619 validate_change (insn, loc, src, 1);
1624 /* Process each of our operands recursively. */
1625 fmt = GET_RTX_FORMAT (code);
1626 for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
1628 replace_in_call_usage (&XEXP (x, i), dst_reg, src, insn);
1629 else if (*fmt == 'E')
1630 for (j = 0; j < XVECLEN (x, i); j++)
1631 replace_in_call_usage (& XVECEXP (x, i, j), dst_reg, src, insn);
1634 /* Try to replace output operand DST in SET, with input operand SRC. SET is
1635 the only set in INSN. INSN has just been recognized and constrained.
1636 SRC is operand number OPERAND_NUMBER in INSN.
1637 DST is operand number MATCH_NUMBER in INSN.
1638 If BACKWARD is nonzero, we have been called in a backward pass.
1639 Return nonzero for success. */
1642 fixup_match_1 (rtx insn, rtx set, rtx src, rtx src_subreg, rtx dst,
1643 int backward, int operand_number, int match_number,
1644 FILE *regmove_dump_file)
1647 rtx post_inc = 0, post_inc_set = 0, search_end = 0;
1649 int num_calls = 0, s_num_calls = 0;
1650 enum rtx_code code = NOTE;
1651 HOST_WIDE_INT insn_const = 0, newconst = 0;
1652 rtx overlap = 0; /* need to move insn ? */
1653 rtx src_note = find_reg_note (insn, REG_DEAD, src), dst_note = NULL_RTX;
1654 int length, s_length;
1658 /* Look for (set (regX) (op regA constX))
1659 (set (regY) (op regA constY))
1661 (set (regA) (op regA constX)).
1662 (set (regY) (op regA constY-constX)).
1663 This works for add and shift operations, if
1664 regA is dead after or set by the second insn. */
1666 code = GET_CODE (SET_SRC (set));
1667 if ((code == PLUS || code == LSHIFTRT
1668 || code == ASHIFT || code == ASHIFTRT)
1669 && XEXP (SET_SRC (set), 0) == src
1670 && GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT)
1671 insn_const = INTVAL (XEXP (SET_SRC (set), 1));
1672 else if (! stable_and_no_regs_but_for_p (SET_SRC (set), src, dst))
1675 /* We might find a src_note while scanning. */
1679 if (regmove_dump_file)
1680 fprintf (regmove_dump_file,
1681 "Could fix operand %d of insn %d matching operand %d.\n",
1682 operand_number, INSN_UID (insn), match_number);
1684 /* If SRC is equivalent to a constant set in a different basic block,
1685 then do not use it for this optimization. We want the equivalence
1686 so that if we have to reload this register, we can reload the
1687 constant, rather than extending the lifespan of the register. */
1688 if (reg_is_remote_constant_p (src, insn, get_insns ()))
1691 /* Scan forward to find the next instruction that
1692 uses the output operand. If the operand dies here,
1693 then replace it in both instructions with
1696 for (length = s_length = 0, p = NEXT_INSN (insn); p; p = NEXT_INSN (p))
1699 replace_in_call_usage (& CALL_INSN_FUNCTION_USAGE (p),
1700 REGNO (dst), src, p);
1702 /* ??? We can't scan past the end of a basic block without updating
1703 the register lifetime info (REG_DEAD/basic_block_live_at_start). */
1704 if (perhaps_ends_bb_p (p))
1706 else if (! INSN_P (p))
1713 if (reg_set_p (src, p) || reg_set_p (dst, p)
1714 || (GET_CODE (PATTERN (p)) == USE
1715 && reg_overlap_mentioned_p (src, XEXP (PATTERN (p), 0))))
1718 /* See if all of DST dies in P. This test is
1719 slightly more conservative than it needs to be. */
1720 if ((dst_note = find_regno_note (p, REG_DEAD, REGNO (dst)))
1721 && (GET_MODE (XEXP (dst_note, 0)) == GET_MODE (dst)))
1723 /* If we would be moving INSN, check that we won't move it
1724 into the shadow of a live a live flags register. */
1725 /* ??? We only try to move it in front of P, although
1726 we could move it anywhere between OVERLAP and P. */
1727 if (overlap && GET_MODE (PREV_INSN (p)) != VOIDmode)
1733 rtx set2 = NULL_RTX;
1735 /* If an optimization is done, the value of SRC while P
1736 is executed will be changed. Check that this is OK. */
1737 if (reg_overlap_mentioned_p (src, PATTERN (p)))
1739 for (q = p; q; q = NEXT_INSN (q))
1741 /* ??? We can't scan past the end of a basic block without
1742 updating the register lifetime info
1743 (REG_DEAD/basic_block_live_at_start). */
1744 if (perhaps_ends_bb_p (q))
1749 else if (! INSN_P (q))
1751 else if (reg_overlap_mentioned_p (src, PATTERN (q))
1752 || reg_set_p (src, q))
1756 set2 = single_set (q);
1757 if (! q || ! set2 || GET_CODE (SET_SRC (set2)) != code
1758 || XEXP (SET_SRC (set2), 0) != src
1759 || GET_CODE (XEXP (SET_SRC (set2), 1)) != CONST_INT
1760 || (SET_DEST (set2) != src
1761 && ! find_reg_note (q, REG_DEAD, src)))
1763 /* If this is a PLUS, we can still save a register by doing
1766 src -= insn_const; .
1767 This also gives opportunities for subsequent
1768 optimizations in the backward pass, so do it there. */
1769 if (code == PLUS && backward
1770 /* Don't do this if we can likely tie DST to SET_DEST
1771 of P later; we can't do this tying here if we got a
1773 && ! (dst_note && ! REG_N_CALLS_CROSSED (REGNO (dst))
1775 && REG_P (SET_DEST (single_set (p)))
1776 && (REGNO (SET_DEST (single_set (p)))
1777 < FIRST_PSEUDO_REGISTER))
1778 /* We may only emit an insn directly after P if we
1779 are not in the shadow of a live flags register. */
1780 && GET_MODE (p) == VOIDmode)
1785 newconst = -insn_const;
1793 newconst = INTVAL (XEXP (SET_SRC (set2), 1)) - insn_const;
1794 /* Reject out of range shifts. */
1797 || ((unsigned HOST_WIDE_INT) newconst
1798 >= (GET_MODE_BITSIZE (GET_MODE
1799 (SET_SRC (set2)))))))
1804 if (SET_DEST (set2) != src)
1805 post_inc_set = set2;
1808 /* We use 1 as last argument to validate_change so that all
1809 changes are accepted or rejected together by apply_change_group
1810 when it is called by validate_replace_rtx . */
1811 validate_change (q, &XEXP (SET_SRC (set2), 1),
1812 GEN_INT (newconst), 1);
1814 validate_change (insn, recog_data.operand_loc[match_number], src, 1);
1815 if (validate_replace_rtx (dst, src_subreg, p))
1820 if (reg_overlap_mentioned_p (dst, PATTERN (p)))
1822 if (! src_note && reg_overlap_mentioned_p (src, PATTERN (p)))
1824 /* INSN was already checked to be movable wrt. the registers that it
1825 sets / uses when we found no REG_DEAD note for src on it, but it
1826 still might clobber the flags register. We'll have to check that
1827 we won't insert it into the shadow of a live flags register when
1828 we finally know where we are to move it. */
1830 src_note = find_reg_note (p, REG_DEAD, src);
1833 /* If we have passed a call instruction, and the pseudo-reg SRC is not
1834 already live across a call, then don't perform the optimization. */
1837 if (REG_N_CALLS_CROSSED (REGNO (src)) == 0)
1851 /* Remove the death note for DST from P. */
1852 remove_note (p, dst_note);
1855 post_inc = emit_insn_after (copy_rtx (PATTERN (insn)), p);
1856 if ((HAVE_PRE_INCREMENT || HAVE_PRE_DECREMENT)
1858 && try_auto_increment (search_end, post_inc, 0, src, newconst, 1))
1860 validate_change (insn, &XEXP (SET_SRC (set), 1), GEN_INT (insn_const), 0);
1861 REG_N_SETS (REGNO (src))++;
1862 REG_LIVE_LENGTH (REGNO (src))++;
1866 /* The lifetime of src and dest overlap,
1867 but we can change this by moving insn. */
1868 rtx pat = PATTERN (insn);
1870 remove_note (overlap, src_note);
1871 if ((HAVE_POST_INCREMENT || HAVE_POST_DECREMENT)
1873 && try_auto_increment (overlap, insn, 0, src, insn_const, 0))
1877 rtx notes = REG_NOTES (insn);
1879 emit_insn_after_with_line_notes (pat, PREV_INSN (p), insn);
1881 /* emit_insn_after_with_line_notes has no
1882 return value, so search for the new insn. */
1884 while (! INSN_P (insn) || PATTERN (insn) != pat)
1885 insn = PREV_INSN (insn);
1887 REG_NOTES (insn) = notes;
1890 /* Sometimes we'd generate src = const; src += n;
1891 if so, replace the instruction that set src
1892 in the first place. */
1894 if (! overlap && (code == PLUS || code == MINUS))
1896 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
1897 rtx q, set2 = NULL_RTX;
1898 int num_calls2 = 0, s_length2 = 0;
1900 if (note && CONSTANT_P (XEXP (note, 0)))
1902 for (q = PREV_INSN (insn); q; q = PREV_INSN (q))
1904 /* ??? We can't scan past the end of a basic block without
1905 updating the register lifetime info
1906 (REG_DEAD/basic_block_live_at_start). */
1907 if (perhaps_ends_bb_p (q))
1912 else if (! INSN_P (q))
1916 if (reg_set_p (src, q))
1918 set2 = single_set (q);
1921 if (reg_overlap_mentioned_p (src, PATTERN (q)))
1929 if (q && set2 && SET_DEST (set2) == src && CONSTANT_P (SET_SRC (set2))
1930 && validate_change (insn, &SET_SRC (set), XEXP (note, 0), 0))
1933 REG_N_SETS (REGNO (src))--;
1934 REG_N_CALLS_CROSSED (REGNO (src)) -= num_calls2;
1935 REG_LIVE_LENGTH (REGNO (src)) -= s_length2;
1941 if ((HAVE_PRE_INCREMENT || HAVE_PRE_DECREMENT)
1942 && (code == PLUS || code == MINUS) && insn_const
1943 && try_auto_increment (p, insn, 0, src, insn_const, 1))
1945 else if ((HAVE_POST_INCREMENT || HAVE_POST_DECREMENT)
1947 && try_auto_increment (p, post_inc, post_inc_set, src, newconst, 0))
1949 /* If post_inc still prevails, try to find an
1950 insn where it can be used as a pre-in/decrement.
1951 If code is MINUS, this was already tried. */
1952 if (post_inc && code == PLUS
1953 /* Check that newconst is likely to be usable
1954 in a pre-in/decrement before starting the search. */
1955 && ((HAVE_PRE_INCREMENT && newconst > 0 && newconst <= MOVE_MAX)
1956 || (HAVE_PRE_DECREMENT && newconst < 0 && newconst >= -MOVE_MAX))
1957 && exact_log2 (newconst))
1961 inc_dest = post_inc_set ? SET_DEST (post_inc_set) : src;
1962 for (q = post_inc; (q = NEXT_INSN (q)); )
1964 /* ??? We can't scan past the end of a basic block without updating
1965 the register lifetime info
1966 (REG_DEAD/basic_block_live_at_start). */
1967 if (perhaps_ends_bb_p (q))
1969 else if (! INSN_P (q))
1971 else if (src != inc_dest
1972 && (reg_overlap_mentioned_p (src, PATTERN (q))
1973 || reg_set_p (src, q)))
1975 else if (reg_set_p (inc_dest, q))
1977 else if (reg_overlap_mentioned_p (inc_dest, PATTERN (q)))
1979 try_auto_increment (q, post_inc,
1980 post_inc_set, inc_dest, newconst, 1);
1986 /* Move the death note for DST to INSN if it is used
1988 if (reg_overlap_mentioned_p (dst, PATTERN (insn)))
1990 XEXP (dst_note, 1) = REG_NOTES (insn);
1991 REG_NOTES (insn) = dst_note;
1996 /* Move the death note for SRC from INSN to P. */
1998 remove_note (insn, src_note);
1999 XEXP (src_note, 1) = REG_NOTES (p);
2000 REG_NOTES (p) = src_note;
2002 REG_N_CALLS_CROSSED (REGNO (src)) += s_num_calls;
2005 REG_N_SETS (REGNO (src))++;
2006 REG_N_SETS (REGNO (dst))--;
2008 REG_N_CALLS_CROSSED (REGNO (dst)) -= num_calls;
2010 REG_LIVE_LENGTH (REGNO (src)) += s_length;
2011 if (REG_LIVE_LENGTH (REGNO (dst)) >= 0)
2013 REG_LIVE_LENGTH (REGNO (dst)) -= length;
2014 /* REG_LIVE_LENGTH is only an approximation after
2015 combine if sched is not run, so make sure that we
2016 still have a reasonable value. */
2017 if (REG_LIVE_LENGTH (REGNO (dst)) < 2)
2018 REG_LIVE_LENGTH (REGNO (dst)) = 2;
2020 if (regmove_dump_file)
2021 fprintf (regmove_dump_file,
2022 "Fixed operand %d of insn %d matching operand %d.\n",
2023 operand_number, INSN_UID (insn), match_number);
2028 /* Return nonzero if X is stable and mentions no registers but for
2029 mentioning SRC or mentioning / changing DST . If in doubt, presume
2031 The rationale is that we want to check if we can move an insn easily
2032 while just paying attention to SRC and DST. */
2034 stable_and_no_regs_but_for_p (rtx x, rtx src, rtx dst)
2036 RTX_CODE code = GET_CODE (x);
2037 switch (GET_RTX_CLASS (code))
2041 case RTX_COMM_ARITH:
2043 case RTX_COMM_COMPARE:
2045 case RTX_BITFIELD_OPS:
2048 const char *fmt = GET_RTX_FORMAT (code);
2049 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2051 && ! stable_and_no_regs_but_for_p (XEXP (x, i), src, dst))
2057 return x == src || x == dst;
2058 /* If this is a MEM, look inside - there might be a register hidden in
2059 the address of an unchanging MEM. */
2061 && ! stable_and_no_regs_but_for_p (XEXP (x, 0), src, dst))
2065 return ! rtx_unstable_p (x);
2069 /* Track stack adjustments and stack memory references. Attempt to
2070 reduce the number of stack adjustments by back-propagating across
2071 the memory references.
2073 This is intended primarily for use with targets that do not define
2074 ACCUMULATE_OUTGOING_ARGS. It is of significantly more value to
2075 targets that define PREFERRED_STACK_BOUNDARY more aligned than
2076 STACK_BOUNDARY (e.g. x86), or if not all registers can be pushed
2077 (e.g. x86 fp regs) which would ordinarily have to be implemented
2078 as a sub/mov pair due to restrictions in calls.c.
2080 Propagation stops when any of the insns that need adjusting are
2081 (a) no longer valid because we've exceeded their range, (b) a
2082 non-trivial push instruction, or (c) a call instruction.
2084 Restriction B is based on the assumption that push instructions
2085 are smaller or faster. If a port really wants to remove all
2086 pushes, it should have defined ACCUMULATE_OUTGOING_ARGS. The
2087 one exception that is made is for an add immediately followed
2090 /* This structure records stack memory references between stack adjusting
2095 HOST_WIDE_INT sp_offset;
2097 struct csa_memlist *next;
2100 static int stack_memref_p (rtx);
2101 static rtx single_set_for_csa (rtx);
2102 static void free_csa_memlist (struct csa_memlist *);
2103 static struct csa_memlist *record_one_stack_memref (rtx, rtx *,
2104 struct csa_memlist *);
2105 static int try_apply_stack_adjustment (rtx, struct csa_memlist *,
2106 HOST_WIDE_INT, HOST_WIDE_INT);
2107 static void combine_stack_adjustments_for_block (basic_block);
2108 static int record_stack_memrefs (rtx *, void *);
2111 /* Main entry point for stack adjustment combination. */
2114 combine_stack_adjustments (void)
2119 combine_stack_adjustments_for_block (bb);
2122 /* Recognize a MEM of the form (sp) or (plus sp const). */
2125 stack_memref_p (rtx x)
2131 if (x == stack_pointer_rtx)
2133 if (GET_CODE (x) == PLUS
2134 && XEXP (x, 0) == stack_pointer_rtx
2135 && GET_CODE (XEXP (x, 1)) == CONST_INT)
2141 /* Recognize either normal single_set or the hack in i386.md for
2142 tying fp and sp adjustments. */
2145 single_set_for_csa (rtx insn)
2148 rtx tmp = single_set (insn);
2152 if (!NONJUMP_INSN_P (insn)
2153 || GET_CODE (PATTERN (insn)) != PARALLEL)
2156 tmp = PATTERN (insn);
2157 if (GET_CODE (XVECEXP (tmp, 0, 0)) != SET)
2160 for (i = 1; i < XVECLEN (tmp, 0); ++i)
2162 rtx this = XVECEXP (tmp, 0, i);
2164 /* The special case is allowing a no-op set. */
2165 if (GET_CODE (this) == SET
2166 && SET_SRC (this) == SET_DEST (this))
2168 else if (GET_CODE (this) != CLOBBER
2169 && GET_CODE (this) != USE)
2173 return XVECEXP (tmp, 0, 0);
2176 /* Free the list of csa_memlist nodes. */
2179 free_csa_memlist (struct csa_memlist *memlist)
2181 struct csa_memlist *next;
2182 for (; memlist ; memlist = next)
2184 next = memlist->next;
2189 /* Create a new csa_memlist node from the given memory reference.
2190 It is already known that the memory is stack_memref_p. */
2192 static struct csa_memlist *
2193 record_one_stack_memref (rtx insn, rtx *mem, struct csa_memlist *next_memlist)
2195 struct csa_memlist *ml;
2197 ml = xmalloc (sizeof (*ml));
2199 if (XEXP (*mem, 0) == stack_pointer_rtx)
2202 ml->sp_offset = INTVAL (XEXP (XEXP (*mem, 0), 1));
2206 ml->next = next_memlist;
2211 /* Attempt to apply ADJUST to the stack adjusting insn INSN, as well
2212 as each of the memories in MEMLIST. Return true on success. */
2215 try_apply_stack_adjustment (rtx insn, struct csa_memlist *memlist, HOST_WIDE_INT new_adjust,
2216 HOST_WIDE_INT delta)
2218 struct csa_memlist *ml;
2221 set = single_set_for_csa (insn);
2222 validate_change (insn, &XEXP (SET_SRC (set), 1), GEN_INT (new_adjust), 1);
2224 for (ml = memlist; ml ; ml = ml->next)
2227 replace_equiv_address_nv (*ml->mem,
2228 plus_constant (stack_pointer_rtx,
2229 ml->sp_offset - delta)), 1);
2231 if (apply_change_group ())
2233 /* Succeeded. Update our knowledge of the memory references. */
2234 for (ml = memlist; ml ; ml = ml->next)
2235 ml->sp_offset -= delta;
2243 /* Called via for_each_rtx and used to record all stack memory references in
2244 the insn and discard all other stack pointer references. */
2245 struct record_stack_memrefs_data
2248 struct csa_memlist *memlist;
2252 record_stack_memrefs (rtx *xp, void *data)
2255 struct record_stack_memrefs_data *d =
2256 (struct record_stack_memrefs_data *) data;
2259 switch (GET_CODE (x))
2262 if (!reg_mentioned_p (stack_pointer_rtx, x))
2264 /* We are not able to handle correctly all possible memrefs containing
2265 stack pointer, so this check is necessary. */
2266 if (stack_memref_p (x))
2268 d->memlist = record_one_stack_memref (d->insn, xp, d->memlist);
2273 /* ??? We want be able to handle non-memory stack pointer
2274 references later. For now just discard all insns referring to
2275 stack pointer outside mem expressions. We would probably
2276 want to teach validate_replace to simplify expressions first.
2278 We can't just compare with STACK_POINTER_RTX because the
2279 reference to the stack pointer might be in some other mode.
2280 In particular, an explicit clobber in an asm statement will
2281 result in a QImode clobber. */
2282 if (REGNO (x) == STACK_POINTER_REGNUM)
2291 /* Subroutine of combine_stack_adjustments, called for each basic block. */
2294 combine_stack_adjustments_for_block (basic_block bb)
2296 HOST_WIDE_INT last_sp_adjust = 0;
2297 rtx last_sp_set = NULL_RTX;
2298 struct csa_memlist *memlist = NULL;
2299 rtx insn, next, set;
2300 struct record_stack_memrefs_data data;
2301 bool end_of_block = false;
2303 for (insn = BB_HEAD (bb); !end_of_block ; insn = next)
2305 end_of_block = insn == BB_END (bb);
2306 next = NEXT_INSN (insn);
2308 if (! INSN_P (insn))
2311 set = single_set_for_csa (insn);
2314 rtx dest = SET_DEST (set);
2315 rtx src = SET_SRC (set);
2317 /* Find constant additions to the stack pointer. */
2318 if (dest == stack_pointer_rtx
2319 && GET_CODE (src) == PLUS
2320 && XEXP (src, 0) == stack_pointer_rtx
2321 && GET_CODE (XEXP (src, 1)) == CONST_INT)
2323 HOST_WIDE_INT this_adjust = INTVAL (XEXP (src, 1));
2325 /* If we've not seen an adjustment previously, record
2326 it now and continue. */
2330 last_sp_adjust = this_adjust;
2334 /* If not all recorded memrefs can be adjusted, or the
2335 adjustment is now too large for a constant addition,
2336 we cannot merge the two stack adjustments.
2338 Also we need to be careful to not move stack pointer
2339 such that we create stack accesses outside the allocated
2340 area. We can combine an allocation into the first insn,
2341 or a deallocation into the second insn. We can not
2342 combine an allocation followed by a deallocation.
2344 The only somewhat frequent occurrence of the later is when
2345 a function allocates a stack frame but does not use it.
2346 For this case, we would need to analyze rtl stream to be
2347 sure that allocated area is really unused. This means not
2348 only checking the memory references, but also all registers
2349 or global memory references possibly containing a stack
2352 Perhaps the best way to address this problem is to teach
2353 gcc not to allocate stack for objects never used. */
2355 /* Combine an allocation into the first instruction. */
2356 if (STACK_GROWS_DOWNWARD ? this_adjust <= 0 : this_adjust >= 0)
2358 if (try_apply_stack_adjustment (last_sp_set, memlist,
2359 last_sp_adjust + this_adjust,
2364 last_sp_adjust += this_adjust;
2369 /* Otherwise we have a deallocation. Do not combine with
2370 a previous allocation. Combine into the second insn. */
2371 else if (STACK_GROWS_DOWNWARD
2372 ? last_sp_adjust >= 0 : last_sp_adjust <= 0)
2374 if (try_apply_stack_adjustment (insn, memlist,
2375 last_sp_adjust + this_adjust,
2379 delete_insn (last_sp_set);
2381 last_sp_adjust += this_adjust;
2382 free_csa_memlist (memlist);
2388 /* Combination failed. Restart processing from here. If
2389 deallocation+allocation conspired to cancel, we can
2390 delete the old deallocation insn. */
2391 if (last_sp_set && last_sp_adjust == 0)
2393 free_csa_memlist (memlist);
2396 last_sp_adjust = this_adjust;
2400 /* Find a predecrement of exactly the previous adjustment and
2401 turn it into a direct store. Obviously we can't do this if
2402 there were any intervening uses of the stack pointer. */
2405 && ((GET_CODE (XEXP (dest, 0)) == PRE_DEC
2407 == (HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest))))
2408 || (GET_CODE (XEXP (dest, 0)) == PRE_MODIFY
2409 && GET_CODE (XEXP (XEXP (dest, 0), 1)) == PLUS
2410 && XEXP (XEXP (XEXP (dest, 0), 1), 0) == stack_pointer_rtx
2411 && (GET_CODE (XEXP (XEXP (XEXP (dest, 0), 1), 1))
2413 && (INTVAL (XEXP (XEXP (XEXP (dest, 0), 1), 1))
2414 == -last_sp_adjust)))
2415 && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx
2416 && ! reg_mentioned_p (stack_pointer_rtx, src)
2417 && memory_address_p (GET_MODE (dest), stack_pointer_rtx)
2418 && validate_change (insn, &SET_DEST (set),
2419 replace_equiv_address (dest,
2423 delete_insn (last_sp_set);
2424 free_csa_memlist (memlist);
2426 last_sp_set = NULL_RTX;
2433 data.memlist = memlist;
2434 if (!CALL_P (insn) && last_sp_set
2435 && !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data))
2437 memlist = data.memlist;
2440 memlist = data.memlist;
2442 /* Otherwise, we were not able to process the instruction.
2443 Do not continue collecting data across such a one. */
2446 || reg_mentioned_p (stack_pointer_rtx, PATTERN (insn))))
2448 if (last_sp_set && last_sp_adjust == 0)
2449 delete_insn (last_sp_set);
2450 free_csa_memlist (memlist);
2452 last_sp_set = NULL_RTX;
2457 if (last_sp_set && last_sp_adjust == 0)
2458 delete_insn (last_sp_set);
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