1 /* Optimize by combining instructions for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This module is essentially the "combiner" phase of the U. of Arizona
22 Portable Optimizer, but redone to work on our list-structured
23 representation for RTL instead of their string representation.
25 The LOG_LINKS of each insn identify the most recent assignment
26 to each REG used in the insn. It is a list of previous insns,
27 each of which contains a SET for a REG that is used in this insn
28 and not used or set in between. LOG_LINKs never cross basic blocks.
29 They were set up by the preceding pass (lifetime analysis).
31 We try to combine each pair of insns joined by a logical link.
32 We also try to combine triples of insns A, B and C when
33 C has a link back to B and B has a link back to A.
35 LOG_LINKS does not have links for use of the CC0. They don't
36 need to, because the insn that sets the CC0 is always immediately
37 before the insn that tests it. So we always regard a branch
38 insn as having a logical link to the preceding insn. The same is true
39 for an insn explicitly using CC0.
41 We check (with use_crosses_set_p) to avoid combining in such a way
42 as to move a computation to a place where its value would be different.
44 Combination is done by mathematically substituting the previous
45 insn(s) values for the regs they set into the expressions in
46 the later insns that refer to these regs. If the result is a valid insn
47 for our target machine, according to the machine description,
48 we install it, delete the earlier insns, and update the data flow
49 information (LOG_LINKS and REG_NOTES) for what we did.
51 There are a few exceptions where the dataflow information created by
52 flow.c aren't completely updated:
54 - reg_live_length is not updated
55 - reg_n_refs is not adjusted in the rare case when a register is
56 no longer required in a computation
57 - there are extremely rare cases (see distribute_regnotes) when a
59 - a LOG_LINKS entry that refers to an insn with multiple SETs may be
60 removed because there is no way to know which register it was
63 To simplify substitution, we combine only when the earlier insn(s)
64 consist of only a single assignment. To simplify updating afterward,
65 we never combine when a subroutine call appears in the middle.
67 Since we do not represent assignments to CC0 explicitly except when that
68 is all an insn does, there is no LOG_LINKS entry in an insn that uses
69 the condition code for the insn that set the condition code.
70 Fortunately, these two insns must be consecutive.
71 Therefore, every JUMP_INSN is taken to have an implicit logical link
72 to the preceding insn. This is not quite right, since non-jumps can
73 also use the condition code; but in practice such insns would not
81 #include "hard-reg-set.h"
83 #include "basic-block.h"
84 #include "insn-config.h"
85 #include "insn-flags.h"
86 #include "insn-codes.h"
87 #include "insn-attr.h"
92 /* It is not safe to use ordinary gen_lowpart in combine.
93 Use gen_lowpart_for_combine instead. See comments there. */
94 #define gen_lowpart dont_use_gen_lowpart_you_dummy
96 /* If byte loads either zero- or sign- extend, define BYTE_LOADS_EXTEND
97 for cases when we don't care which is true. Define LOAD_EXTEND to
98 be ZERO_EXTEND or SIGN_EXTEND, depending on which was defined. */
100 #ifdef BYTE_LOADS_ZERO_EXTEND
101 #define BYTE_LOADS_EXTEND
102 #define LOAD_EXTEND ZERO_EXTEND
105 #ifdef BYTE_LOADS_SIGN_EXTEND
106 #define BYTE_LOADS_EXTEND
107 #define LOAD_EXTEND SIGN_EXTEND
110 /* Number of attempts to combine instructions in this function. */
112 static int combine_attempts;
114 /* Number of attempts that got as far as substitution in this function. */
116 static int combine_merges;
118 /* Number of instructions combined with added SETs in this function. */
120 static int combine_extras;
122 /* Number of instructions combined in this function. */
124 static int combine_successes;
126 /* Totals over entire compilation. */
128 static int total_attempts, total_merges, total_extras, total_successes;
130 /* Vector mapping INSN_UIDs to cuids.
131 The cuids are like uids but increase monotonically always.
132 Combine always uses cuids so that it can compare them.
133 But actually renumbering the uids, which we used to do,
134 proves to be a bad idea because it makes it hard to compare
135 the dumps produced by earlier passes with those from later passes. */
137 static int *uid_cuid;
139 /* Get the cuid of an insn. */
141 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
143 /* Maximum register number, which is the size of the tables below. */
145 static int combine_max_regno;
147 /* Record last point of death of (hard or pseudo) register n. */
149 static rtx *reg_last_death;
151 /* Record last point of modification of (hard or pseudo) register n. */
153 static rtx *reg_last_set;
155 /* Record the cuid of the last insn that invalidated memory
156 (anything that writes memory, and subroutine calls, but not pushes). */
158 static int mem_last_set;
160 /* Record the cuid of the last CALL_INSN
161 so we can tell whether a potential combination crosses any calls. */
163 static int last_call_cuid;
165 /* When `subst' is called, this is the insn that is being modified
166 (by combining in a previous insn). The PATTERN of this insn
167 is still the old pattern partially modified and it should not be
168 looked at, but this may be used to examine the successors of the insn
169 to judge whether a simplification is valid. */
171 static rtx subst_insn;
173 /* This is the lowest CUID that `subst' is currently dealing with.
174 get_last_value will not return a value if the register was set at or
175 after this CUID. If not for this mechanism, we could get confused if
176 I2 or I1 in try_combine were an insn that used the old value of a register
177 to obtain a new value. In that case, we might erroneously get the
178 new value of the register when we wanted the old one. */
180 static int subst_low_cuid;
182 /* This is the value of undobuf.num_undo when we started processing this
183 substitution. This will prevent gen_rtx_combine from re-used a piece
184 from the previous expression. Doing so can produce circular rtl
187 static int previous_num_undos;
189 /* The next group of arrays allows the recording of the last value assigned
190 to (hard or pseudo) register n. We use this information to see if a
191 operation being processed is redundant given a prior operation performed
192 on the register. For example, an `and' with a constant is redundant if
193 all the zero bits are already known to be turned off.
195 We use an approach similar to that used by cse, but change it in the
198 (1) We do not want to reinitialize at each label.
199 (2) It is useful, but not critical, to know the actual value assigned
200 to a register. Often just its form is helpful.
202 Therefore, we maintain the following arrays:
204 reg_last_set_value the last value assigned
205 reg_last_set_label records the value of label_tick when the
206 register was assigned
207 reg_last_set_table_tick records the value of label_tick when a
208 value using the register is assigned
209 reg_last_set_invalid set to non-zero when it is not valid
210 to use the value of this register in some
213 To understand the usage of these tables, it is important to understand
214 the distinction between the value in reg_last_set_value being valid
215 and the register being validly contained in some other expression in the
218 Entry I in reg_last_set_value is valid if it is non-zero, and either
219 reg_n_sets[i] is 1 or reg_last_set_label[i] == label_tick.
221 Register I may validly appear in any expression returned for the value
222 of another register if reg_n_sets[i] is 1. It may also appear in the
223 value for register J if reg_last_set_label[i] < reg_last_set_label[j] or
224 reg_last_set_invalid[j] is zero.
226 If an expression is found in the table containing a register which may
227 not validly appear in an expression, the register is replaced by
228 something that won't match, (clobber (const_int 0)).
230 reg_last_set_invalid[i] is set non-zero when register I is being assigned
231 to and reg_last_set_table_tick[i] == label_tick. */
233 /* Record last value assigned to (hard or pseudo) register n. */
235 static rtx *reg_last_set_value;
237 /* Record the value of label_tick when the value for register n is placed in
238 reg_last_set_value[n]. */
240 static int *reg_last_set_label;
242 /* Record the value of label_tick when an expression involving register n
243 is placed in reg_last_set_value. */
245 static int *reg_last_set_table_tick;
247 /* Set non-zero if references to register n in expressions should not be
250 static char *reg_last_set_invalid;
252 /* Incremented for each label. */
254 static int label_tick;
256 /* Some registers that are set more than once and used in more than one
257 basic block are nevertheless always set in similar ways. For example,
258 a QImode register may be loaded from memory in two places on a machine
259 where byte loads zero extend.
261 We record in the following array what we know about the nonzero
262 bits of a register, specifically which bits are known to be zero.
264 If an entry is zero, it means that we don't know anything special. */
266 static unsigned HOST_WIDE_INT *reg_nonzero_bits;
268 /* Mode used to compute significance in reg_nonzero_bits. It is the largest
269 integer mode that can fit in HOST_BITS_PER_WIDE_INT. */
271 static enum machine_mode nonzero_bits_mode;
273 /* Nonzero if we know that a register has some leading bits that are always
274 equal to the sign bit. */
276 static char *reg_sign_bit_copies;
278 /* Nonzero when reg_nonzero_bits and reg_sign_bit_copies can be safely used.
279 It is zero while computing them and after combine has completed. This
280 former test prevents propagating values based on previously set values,
281 which can be incorrect if a variable is modified in a loop. */
283 static int nonzero_sign_valid;
285 /* These arrays are maintained in parallel with reg_last_set_value
286 and are used to store the mode in which the register was last set,
287 the bits that were known to be zero when it was last set, and the
288 number of sign bits copies it was known to have when it was last set. */
290 static enum machine_mode *reg_last_set_mode;
291 static unsigned HOST_WIDE_INT *reg_last_set_nonzero_bits;
292 static char *reg_last_set_sign_bit_copies;
294 /* Record one modification to rtl structure
295 to be undone by storing old_contents into *where.
296 is_int is 1 if the contents are an int. */
301 union {rtx rtx; int i;} old_contents;
302 union {rtx *rtx; int *i;} where;
305 /* Record a bunch of changes to be undone, up to MAX_UNDO of them.
306 num_undo says how many are currently recorded.
308 storage is nonzero if we must undo the allocation of new storage.
309 The value of storage is what to pass to obfree.
311 other_insn is nonzero if we have modified some other insn in the process
312 of working on subst_insn. It must be verified too. */
320 struct undo undo[MAX_UNDO];
324 static struct undobuf undobuf;
326 /* Substitute NEWVAL, an rtx expression, into INTO, a place in some
327 insn. The substitution can be undone by undo_all. If INTO is already
328 set to NEWVAL, do not record this change. Because computing NEWVAL might
329 also call SUBST, we have to compute it before we put anything into
332 #define SUBST(INTO, NEWVAL) \
333 do { rtx _new = (NEWVAL); \
334 if (undobuf.num_undo < MAX_UNDO) \
336 undobuf.undo[undobuf.num_undo].is_int = 0; \
337 undobuf.undo[undobuf.num_undo].where.rtx = &INTO; \
338 undobuf.undo[undobuf.num_undo].old_contents.rtx = INTO; \
340 if (undobuf.undo[undobuf.num_undo].old_contents.rtx != INTO) \
341 undobuf.num_undo++; \
345 /* Similar to SUBST, but NEWVAL is an int. INTO will normally be an XINT
347 Note that substitution for the value of a CONST_INT is not safe. */
349 #define SUBST_INT(INTO, NEWVAL) \
350 do { if (undobuf.num_undo < MAX_UNDO) \
352 undobuf.undo[undobuf.num_undo].is_int = 1; \
353 undobuf.undo[undobuf.num_undo].where.i = (int *) &INTO; \
354 undobuf.undo[undobuf.num_undo].old_contents.i = INTO; \
356 if (undobuf.undo[undobuf.num_undo].old_contents.i != INTO) \
357 undobuf.num_undo++; \
361 /* Number of times the pseudo being substituted for
362 was found and replaced. */
364 static int n_occurrences;
366 static void set_nonzero_bits_and_sign_copies ();
367 static void setup_incoming_promotions ();
368 static void move_deaths ();
370 static void record_value_for_reg ();
371 static void record_dead_and_set_regs ();
372 static int use_crosses_set_p ();
373 static rtx try_combine ();
374 static rtx *find_split_point ();
376 static void undo_all ();
377 static int reg_dead_at_p ();
378 static rtx expand_compound_operation ();
379 static rtx expand_field_assignment ();
380 static rtx make_extraction ();
381 static int get_pos_from_mask ();
382 static rtx force_to_mode ();
383 static rtx known_cond ();
384 static rtx make_field_assignment ();
385 static rtx make_compound_operation ();
386 static rtx apply_distributive_law ();
387 static rtx simplify_and_const_int ();
388 static unsigned HOST_WIDE_INT nonzero_bits ();
389 static int num_sign_bit_copies ();
390 static int merge_outer_ops ();
391 static rtx simplify_shift_const ();
392 static int recog_for_combine ();
393 static rtx gen_lowpart_for_combine ();
394 static rtx gen_rtx_combine ();
395 static rtx gen_binary ();
396 static rtx gen_unary ();
397 static enum rtx_code simplify_comparison ();
398 static int reversible_comparison_p ();
399 static int get_last_value_validate ();
400 static rtx get_last_value ();
401 static void distribute_notes ();
402 static void distribute_links ();
404 /* Main entry point for combiner. F is the first insn of the function.
405 NREGS is the first unused pseudo-reg number. */
408 combine_instructions (f, nregs)
412 register rtx insn, next, prev;
414 register rtx links, nextlinks;
416 combine_attempts = 0;
419 combine_successes = 0;
420 undobuf.num_undo = previous_num_undos = 0;
422 combine_max_regno = nregs;
424 reg_last_death = (rtx *) alloca (nregs * sizeof (rtx));
425 reg_last_set = (rtx *) alloca (nregs * sizeof (rtx));
426 reg_last_set_value = (rtx *) alloca (nregs * sizeof (rtx));
427 reg_last_set_table_tick = (int *) alloca (nregs * sizeof (int));
428 reg_last_set_label = (int *) alloca (nregs * sizeof (int));
429 reg_last_set_invalid = (char *) alloca (nregs * sizeof (char));
431 = (enum machine_mode *) alloca (nregs * sizeof (enum machine_mode));
432 reg_last_set_nonzero_bits
433 = (unsigned HOST_WIDE_INT *) alloca (nregs * sizeof (HOST_WIDE_INT));
434 reg_last_set_sign_bit_copies
435 = (char *) alloca (nregs * sizeof (char));
438 = (unsigned HOST_WIDE_INT *) alloca (nregs * sizeof (HOST_WIDE_INT));
439 reg_sign_bit_copies = (char *) alloca (nregs * sizeof (char));
441 bzero (reg_last_death, nregs * sizeof (rtx));
442 bzero (reg_last_set, nregs * sizeof (rtx));
443 bzero (reg_last_set_value, nregs * sizeof (rtx));
444 bzero (reg_last_set_table_tick, nregs * sizeof (int));
445 bzero (reg_last_set_label, nregs * sizeof (int));
446 bzero (reg_last_set_invalid, nregs * sizeof (char));
447 bzero (reg_last_set_mode, nregs * sizeof (enum machine_mode));
448 bzero (reg_last_set_nonzero_bits, nregs * sizeof (HOST_WIDE_INT));
449 bzero (reg_last_set_sign_bit_copies, nregs * sizeof (char));
450 bzero (reg_nonzero_bits, nregs * sizeof (HOST_WIDE_INT));
451 bzero (reg_sign_bit_copies, nregs * sizeof (char));
453 init_recog_no_volatile ();
455 /* Compute maximum uid value so uid_cuid can be allocated. */
457 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
458 if (INSN_UID (insn) > i)
461 uid_cuid = (int *) alloca ((i + 1) * sizeof (int));
463 nonzero_bits_mode = mode_for_size (HOST_BITS_PER_WIDE_INT, MODE_INT, 0);
465 /* Don't use reg_nonzero_bits when computing it. This can cause problems
466 when, for example, we have j <<= 1 in a loop. */
468 nonzero_sign_valid = 0;
470 /* Compute the mapping from uids to cuids.
471 Cuids are numbers assigned to insns, like uids,
472 except that cuids increase monotonically through the code.
474 Scan all SETs and see if we can deduce anything about what
475 bits are known to be zero for some registers and how many copies
476 of the sign bit are known to exist for those registers.
478 Also set any known values so that we can use it while searching
479 for what bits are known to be set. */
483 setup_incoming_promotions ();
485 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
487 INSN_CUID (insn) = ++i;
491 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
493 note_stores (PATTERN (insn), set_nonzero_bits_and_sign_copies);
494 record_dead_and_set_regs (insn);
497 if (GET_CODE (insn) == CODE_LABEL)
501 nonzero_sign_valid = 1;
503 /* Now scan all the insns in forward order. */
508 bzero (reg_last_death, nregs * sizeof (rtx));
509 bzero (reg_last_set, nregs * sizeof (rtx));
510 bzero (reg_last_set_value, nregs * sizeof (rtx));
511 bzero (reg_last_set_table_tick, nregs * sizeof (int));
512 bzero (reg_last_set_label, nregs * sizeof (int));
513 bzero (reg_last_set_invalid, nregs * sizeof (char));
515 setup_incoming_promotions ();
517 for (insn = f; insn; insn = next ? next : NEXT_INSN (insn))
521 if (GET_CODE (insn) == CODE_LABEL)
524 else if (GET_CODE (insn) == INSN
525 || GET_CODE (insn) == CALL_INSN
526 || GET_CODE (insn) == JUMP_INSN)
528 /* Try this insn with each insn it links back to. */
530 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
531 if ((next = try_combine (insn, XEXP (links, 0), NULL_RTX)) != 0)
534 /* Try each sequence of three linked insns ending with this one. */
536 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
537 for (nextlinks = LOG_LINKS (XEXP (links, 0)); nextlinks;
538 nextlinks = XEXP (nextlinks, 1))
539 if ((next = try_combine (insn, XEXP (links, 0),
540 XEXP (nextlinks, 0))) != 0)
544 /* Try to combine a jump insn that uses CC0
545 with a preceding insn that sets CC0, and maybe with its
546 logical predecessor as well.
547 This is how we make decrement-and-branch insns.
548 We need this special code because data flow connections
549 via CC0 do not get entered in LOG_LINKS. */
551 if (GET_CODE (insn) == JUMP_INSN
552 && (prev = prev_nonnote_insn (insn)) != 0
553 && GET_CODE (prev) == INSN
554 && sets_cc0_p (PATTERN (prev)))
556 if ((next = try_combine (insn, prev, NULL_RTX)) != 0)
559 for (nextlinks = LOG_LINKS (prev); nextlinks;
560 nextlinks = XEXP (nextlinks, 1))
561 if ((next = try_combine (insn, prev,
562 XEXP (nextlinks, 0))) != 0)
566 /* Do the same for an insn that explicitly references CC0. */
567 if (GET_CODE (insn) == INSN
568 && (prev = prev_nonnote_insn (insn)) != 0
569 && GET_CODE (prev) == INSN
570 && sets_cc0_p (PATTERN (prev))
571 && GET_CODE (PATTERN (insn)) == SET
572 && reg_mentioned_p (cc0_rtx, SET_SRC (PATTERN (insn))))
574 if ((next = try_combine (insn, prev, NULL_RTX)) != 0)
577 for (nextlinks = LOG_LINKS (prev); nextlinks;
578 nextlinks = XEXP (nextlinks, 1))
579 if ((next = try_combine (insn, prev,
580 XEXP (nextlinks, 0))) != 0)
584 /* Finally, see if any of the insns that this insn links to
585 explicitly references CC0. If so, try this insn, that insn,
586 and its predecessor if it sets CC0. */
587 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
588 if (GET_CODE (XEXP (links, 0)) == INSN
589 && GET_CODE (PATTERN (XEXP (links, 0))) == SET
590 && reg_mentioned_p (cc0_rtx, SET_SRC (PATTERN (XEXP (links, 0))))
591 && (prev = prev_nonnote_insn (XEXP (links, 0))) != 0
592 && GET_CODE (prev) == INSN
593 && sets_cc0_p (PATTERN (prev))
594 && (next = try_combine (insn, XEXP (links, 0), prev)) != 0)
598 /* Try combining an insn with two different insns whose results it
600 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
601 for (nextlinks = XEXP (links, 1); nextlinks;
602 nextlinks = XEXP (nextlinks, 1))
603 if ((next = try_combine (insn, XEXP (links, 0),
604 XEXP (nextlinks, 0))) != 0)
607 if (GET_CODE (insn) != NOTE)
608 record_dead_and_set_regs (insn);
615 total_attempts += combine_attempts;
616 total_merges += combine_merges;
617 total_extras += combine_extras;
618 total_successes += combine_successes;
620 nonzero_sign_valid = 0;
623 /* Set up any promoted values for incoming argument registers. */
626 setup_incoming_promotions ()
628 #ifdef PROMOTE_FUNCTION_ARGS
631 enum machine_mode mode;
633 rtx first = get_insns ();
635 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
636 if (FUNCTION_ARG_REGNO_P (regno)
637 && (reg = promoted_input_arg (regno, &mode, &unsignedp)) != 0)
638 record_value_for_reg (reg, first,
639 gen_rtx (unsignedp ? ZERO_EXTEND : SIGN_EXTEND,
641 gen_rtx (CLOBBER, mode, const0_rtx)));
645 /* Called via note_stores. If X is a pseudo that is used in more than
646 one basic block, is narrower that HOST_BITS_PER_WIDE_INT, and is being
647 set, record what bits are known zero. If we are clobbering X,
648 ignore this "set" because the clobbered value won't be used.
650 If we are setting only a portion of X and we can't figure out what
651 portion, assume all bits will be used since we don't know what will
654 Similarly, set how many bits of X are known to be copies of the sign bit
655 at all locations in the function. This is the smallest number implied
659 set_nonzero_bits_and_sign_copies (x, set)
665 if (GET_CODE (x) == REG
666 && REGNO (x) >= FIRST_PSEUDO_REGISTER
667 && reg_n_sets[REGNO (x)] > 1
668 && reg_basic_block[REGNO (x)] < 0
669 /* If this register is undefined at the start of the file, we can't
670 say what its contents were. */
671 && ! (basic_block_live_at_start[0][REGNO (x) / REGSET_ELT_BITS]
672 & ((REGSET_ELT_TYPE) 1 << (REGNO (x) % REGSET_ELT_BITS)))
673 && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT)
675 if (GET_CODE (set) == CLOBBER)
677 reg_nonzero_bits[REGNO (x)] = GET_MODE_MASK (GET_MODE (x));
678 reg_sign_bit_copies[REGNO (x)] = 0;
682 /* If this is a complex assignment, see if we can convert it into a
683 simple assignment. */
684 set = expand_field_assignment (set);
686 /* If this is a simple assignment, or we have a paradoxical SUBREG,
687 set what we know about X. */
689 if (SET_DEST (set) == x
690 || (GET_CODE (SET_DEST (set)) == SUBREG
691 && (GET_MODE_SIZE (GET_MODE (SET_DEST (set)))
692 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (set)))))
693 && SUBREG_REG (SET_DEST (set)) == x))
695 rtx src = SET_SRC (set);
697 #ifdef SHORT_IMMEDIATES_SIGN_EXTEND
698 /* If X is narrower than a word and SRC is a non-negative
699 constant that would appear negative in the mode of X,
700 sign-extend it for use in reg_nonzero_bits because some
701 machines (maybe most) will actually do the sign-extension
702 and this is the conservative approach.
704 ??? For 2.5, try to tighten up the MD files in this regard
705 instead of this kludge. */
707 if (GET_MODE_BITSIZE (GET_MODE (x)) < BITS_PER_WORD
708 && GET_CODE (src) == CONST_INT
710 && 0 != (INTVAL (src)
712 << GET_MODE_BITSIZE (GET_MODE (x)))))
713 src = GEN_INT (INTVAL (src)
714 | ((HOST_WIDE_INT) (-1)
715 << GET_MODE_BITSIZE (GET_MODE (x))));
718 reg_nonzero_bits[REGNO (x)]
719 |= nonzero_bits (src, nonzero_bits_mode);
720 num = num_sign_bit_copies (SET_SRC (set), GET_MODE (x));
721 if (reg_sign_bit_copies[REGNO (x)] == 0
722 || reg_sign_bit_copies[REGNO (x)] > num)
723 reg_sign_bit_copies[REGNO (x)] = num;
727 reg_nonzero_bits[REGNO (x)] = GET_MODE_MASK (GET_MODE (x));
728 reg_sign_bit_copies[REGNO (x)] = 0;
733 /* See if INSN can be combined into I3. PRED and SUCC are optionally
734 insns that were previously combined into I3 or that will be combined
735 into the merger of INSN and I3.
737 Return 0 if the combination is not allowed for any reason.
739 If the combination is allowed, *PDEST will be set to the single
740 destination of INSN and *PSRC to the single source, and this function
744 can_combine_p (insn, i3, pred, succ, pdest, psrc)
751 rtx set = 0, src, dest;
753 int all_adjacent = (succ ? (next_active_insn (insn) == succ
754 && next_active_insn (succ) == i3)
755 : next_active_insn (insn) == i3);
757 /* Can combine only if previous insn is a SET of a REG, a SUBREG or CC0.
758 or a PARALLEL consisting of such a SET and CLOBBERs.
760 If INSN has CLOBBER parallel parts, ignore them for our processing.
761 By definition, these happen during the execution of the insn. When it
762 is merged with another insn, all bets are off. If they are, in fact,
763 needed and aren't also supplied in I3, they may be added by
764 recog_for_combine. Otherwise, it won't match.
766 We can also ignore a SET whose SET_DEST is mentioned in a REG_UNUSED
769 Get the source and destination of INSN. If more than one, can't
772 if (GET_CODE (PATTERN (insn)) == SET)
773 set = PATTERN (insn);
774 else if (GET_CODE (PATTERN (insn)) == PARALLEL
775 && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == SET)
777 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
779 rtx elt = XVECEXP (PATTERN (insn), 0, i);
781 switch (GET_CODE (elt))
783 /* We can ignore CLOBBERs. */
788 /* Ignore SETs whose result isn't used but not those that
789 have side-effects. */
790 if (find_reg_note (insn, REG_UNUSED, SET_DEST (elt))
791 && ! side_effects_p (elt))
794 /* If we have already found a SET, this is a second one and
795 so we cannot combine with this insn. */
803 /* Anything else means we can't combine. */
809 /* If SET_SRC is an ASM_OPERANDS we can't throw away these CLOBBERs,
810 so don't do anything with it. */
811 || GET_CODE (SET_SRC (set)) == ASM_OPERANDS)
820 set = expand_field_assignment (set);
821 src = SET_SRC (set), dest = SET_DEST (set);
823 /* Don't eliminate a store in the stack pointer. */
824 if (dest == stack_pointer_rtx
825 /* Don't install a subreg involving two modes not tieable.
826 It can worsen register allocation, and can even make invalid reload
827 insns, since the reg inside may need to be copied from in the
828 outside mode, and that may be invalid if it is an fp reg copied in
829 integer mode. As a special exception, we can allow this if
830 I3 is simply copying DEST, a REG, to CC0. */
831 || (GET_CODE (src) == SUBREG
832 && ! MODES_TIEABLE_P (GET_MODE (src), GET_MODE (SUBREG_REG (src)))
834 && ! (GET_CODE (i3) == INSN && GET_CODE (PATTERN (i3)) == SET
835 && SET_DEST (PATTERN (i3)) == cc0_rtx
836 && GET_CODE (dest) == REG && dest == SET_SRC (PATTERN (i3)))
839 /* If we couldn't eliminate a field assignment, we can't combine. */
840 || GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == STRICT_LOW_PART
841 /* Don't combine with an insn that sets a register to itself if it has
842 a REG_EQUAL note. This may be part of a REG_NO_CONFLICT sequence. */
843 || (rtx_equal_p (src, dest) && find_reg_note (insn, REG_EQUAL, NULL_RTX))
844 /* Can't merge a function call. */
845 || GET_CODE (src) == CALL
846 /* Don't substitute into an incremented register. */
847 || FIND_REG_INC_NOTE (i3, dest)
848 || (succ && FIND_REG_INC_NOTE (succ, dest))
849 /* Don't combine the end of a libcall into anything. */
850 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
851 /* Make sure that DEST is not used after SUCC but before I3. */
852 || (succ && ! all_adjacent
853 && reg_used_between_p (dest, succ, i3))
854 /* Make sure that the value that is to be substituted for the register
855 does not use any registers whose values alter in between. However,
856 If the insns are adjacent, a use can't cross a set even though we
857 think it might (this can happen for a sequence of insns each setting
858 the same destination; reg_last_set of that register might point to
859 a NOTE). Also, don't move a volatile asm or UNSPEC_VOLATILE across
862 && (use_crosses_set_p (src, INSN_CUID (insn))
863 || (GET_CODE (src) == ASM_OPERANDS && MEM_VOLATILE_P (src))
864 || GET_CODE (src) == UNSPEC_VOLATILE))
865 /* If there is a REG_NO_CONFLICT note for DEST in I3 or SUCC, we get
866 better register allocation by not doing the combine. */
867 || find_reg_note (i3, REG_NO_CONFLICT, dest)
868 || (succ && find_reg_note (succ, REG_NO_CONFLICT, dest))
869 /* Don't combine across a CALL_INSN, because that would possibly
870 change whether the life span of some REGs crosses calls or not,
871 and it is a pain to update that information.
872 Exception: if source is a constant, moving it later can't hurt.
873 Accept that special case, because it helps -fforce-addr a lot. */
874 || (INSN_CUID (insn) < last_call_cuid && ! CONSTANT_P (src)))
877 /* DEST must either be a REG or CC0. */
878 if (GET_CODE (dest) == REG)
880 /* If register alignment is being enforced for multi-word items in all
881 cases except for parameters, it is possible to have a register copy
882 insn referencing a hard register that is not allowed to contain the
883 mode being copied and which would not be valid as an operand of most
884 insns. Eliminate this problem by not combining with such an insn.
886 Also, on some machines we don't want to extend the life of a hard
889 if (GET_CODE (src) == REG
890 && ((REGNO (dest) < FIRST_PSEUDO_REGISTER
891 && ! HARD_REGNO_MODE_OK (REGNO (dest), GET_MODE (dest)))
892 #ifdef SMALL_REGISTER_CLASSES
893 /* Don't extend the life of a hard register. */
894 || REGNO (src) < FIRST_PSEUDO_REGISTER
896 || (REGNO (src) < FIRST_PSEUDO_REGISTER
897 && ! HARD_REGNO_MODE_OK (REGNO (src), GET_MODE (src)))
902 else if (GET_CODE (dest) != CC0)
905 /* Don't substitute for a register intended as a clobberable operand.
906 Similarly, don't substitute an expression containing a register that
907 will be clobbered in I3. */
908 if (GET_CODE (PATTERN (i3)) == PARALLEL)
909 for (i = XVECLEN (PATTERN (i3), 0) - 1; i >= 0; i--)
910 if (GET_CODE (XVECEXP (PATTERN (i3), 0, i)) == CLOBBER
911 && (reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (i3), 0, i), 0),
913 || rtx_equal_p (XEXP (XVECEXP (PATTERN (i3), 0, i), 0), dest)))
916 /* If INSN contains anything volatile, or is an `asm' (whether volatile
917 or not), reject, unless nothing volatile comes between it and I3,
918 with the exception of SUCC. */
920 if (GET_CODE (src) == ASM_OPERANDS || volatile_refs_p (src))
921 for (p = NEXT_INSN (insn); p != i3; p = NEXT_INSN (p))
922 if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
923 && p != succ && volatile_refs_p (PATTERN (p)))
926 /* If INSN or I2 contains an autoincrement or autodecrement,
927 make sure that register is not used between there and I3,
928 and not already used in I3 either.
929 Also insist that I3 not be a jump; if it were one
930 and the incremented register were spilled, we would lose. */
933 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
934 if (REG_NOTE_KIND (link) == REG_INC
935 && (GET_CODE (i3) == JUMP_INSN
936 || reg_used_between_p (XEXP (link, 0), insn, i3)
937 || reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i3))))
942 /* Don't combine an insn that follows a CC0-setting insn.
943 An insn that uses CC0 must not be separated from the one that sets it.
944 We do, however, allow I2 to follow a CC0-setting insn if that insn
945 is passed as I1; in that case it will be deleted also.
946 We also allow combining in this case if all the insns are adjacent
947 because that would leave the two CC0 insns adjacent as well.
948 It would be more logical to test whether CC0 occurs inside I1 or I2,
949 but that would be much slower, and this ought to be equivalent. */
951 p = prev_nonnote_insn (insn);
952 if (p && p != pred && GET_CODE (p) == INSN && sets_cc0_p (PATTERN (p))
957 /* If we get here, we have passed all the tests and the combination is
966 /* LOC is the location within I3 that contains its pattern or the component
967 of a PARALLEL of the pattern. We validate that it is valid for combining.
969 One problem is if I3 modifies its output, as opposed to replacing it
970 entirely, we can't allow the output to contain I2DEST or I1DEST as doing
971 so would produce an insn that is not equivalent to the original insns.
975 (set (reg:DI 101) (reg:DI 100))
976 (set (subreg:SI (reg:DI 101) 0) <foo>)
978 This is NOT equivalent to:
980 (parallel [(set (subreg:SI (reg:DI 100) 0) <foo>)
981 (set (reg:DI 101) (reg:DI 100))])
983 Not only does this modify 100 (in which case it might still be valid
984 if 100 were dead in I2), it sets 101 to the ORIGINAL value of 100.
986 We can also run into a problem if I2 sets a register that I1
987 uses and I1 gets directly substituted into I3 (not via I2). In that
988 case, we would be getting the wrong value of I2DEST into I3, so we
989 must reject the combination. This case occurs when I2 and I1 both
990 feed into I3, rather than when I1 feeds into I2, which feeds into I3.
991 If I1_NOT_IN_SRC is non-zero, it means that finding I1 in the source
992 of a SET must prevent combination from occurring.
994 On machines where SMALL_REGISTER_CLASSES is defined, we don't combine
995 if the destination of a SET is a hard register.
997 Before doing the above check, we first try to expand a field assignment
998 into a set of logical operations.
1000 If PI3_DEST_KILLED is non-zero, it is a pointer to a location in which
1001 we place a register that is both set and used within I3. If more than one
1002 such register is detected, we fail.
1004 Return 1 if the combination is valid, zero otherwise. */
1007 combinable_i3pat (i3, loc, i2dest, i1dest, i1_not_in_src, pi3dest_killed)
1013 rtx *pi3dest_killed;
1017 if (GET_CODE (x) == SET)
1019 rtx set = expand_field_assignment (x);
1020 rtx dest = SET_DEST (set);
1021 rtx src = SET_SRC (set);
1022 rtx inner_dest = dest, inner_src = src;
1026 while (GET_CODE (inner_dest) == STRICT_LOW_PART
1027 || GET_CODE (inner_dest) == SUBREG
1028 || GET_CODE (inner_dest) == ZERO_EXTRACT)
1029 inner_dest = XEXP (inner_dest, 0);
1031 /* We probably don't need this any more now that LIMIT_RELOAD_CLASS
1034 while (GET_CODE (inner_src) == STRICT_LOW_PART
1035 || GET_CODE (inner_src) == SUBREG
1036 || GET_CODE (inner_src) == ZERO_EXTRACT)
1037 inner_src = XEXP (inner_src, 0);
1039 /* If it is better that two different modes keep two different pseudos,
1040 avoid combining them. This avoids producing the following pattern
1042 (set (subreg:SI (reg/v:QI 21) 0)
1043 (lshiftrt:SI (reg/v:SI 20)
1045 If that were made, reload could not handle the pair of
1046 reg 20/21, since it would try to get any GENERAL_REGS
1047 but some of them don't handle QImode. */
1049 if (rtx_equal_p (inner_src, i2dest)
1050 && GET_CODE (inner_dest) == REG
1051 && ! MODES_TIEABLE_P (GET_MODE (i2dest), GET_MODE (inner_dest)))
1055 /* Check for the case where I3 modifies its output, as
1057 if ((inner_dest != dest
1058 && (reg_overlap_mentioned_p (i2dest, inner_dest)
1059 || (i1dest && reg_overlap_mentioned_p (i1dest, inner_dest))))
1060 /* This is the same test done in can_combine_p except that we
1061 allow a hard register with SMALL_REGISTER_CLASSES if SRC is a
1063 || (GET_CODE (inner_dest) == REG
1064 && REGNO (inner_dest) < FIRST_PSEUDO_REGISTER
1065 #ifdef SMALL_REGISTER_CLASSES
1066 && GET_CODE (src) != CALL
1068 && ! HARD_REGNO_MODE_OK (REGNO (inner_dest),
1069 GET_MODE (inner_dest))
1073 || (i1_not_in_src && reg_overlap_mentioned_p (i1dest, src)))
1076 /* If DEST is used in I3, it is being killed in this insn,
1077 so record that for later.
1078 Never add REG_DEAD notes for the FRAME_POINTER_REGNUM or the
1079 STACK_POINTER_REGNUM, since these are always considered to be
1080 live. Similarly for ARG_POINTER_REGNUM if it is fixed. */
1081 if (pi3dest_killed && GET_CODE (dest) == REG
1082 && reg_referenced_p (dest, PATTERN (i3))
1083 && REGNO (dest) != FRAME_POINTER_REGNUM
1084 #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM
1085 && (REGNO (dest) != ARG_POINTER_REGNUM
1086 || ! fixed_regs [REGNO (dest)])
1088 && REGNO (dest) != STACK_POINTER_REGNUM)
1090 if (*pi3dest_killed)
1093 *pi3dest_killed = dest;
1097 else if (GET_CODE (x) == PARALLEL)
1101 for (i = 0; i < XVECLEN (x, 0); i++)
1102 if (! combinable_i3pat (i3, &XVECEXP (x, 0, i), i2dest, i1dest,
1103 i1_not_in_src, pi3dest_killed))
1110 /* Try to combine the insns I1 and I2 into I3.
1111 Here I1 and I2 appear earlier than I3.
1112 I1 can be zero; then we combine just I2 into I3.
1114 It we are combining three insns and the resulting insn is not recognized,
1115 try splitting it into two insns. If that happens, I2 and I3 are retained
1116 and I1 is pseudo-deleted by turning it into a NOTE. Otherwise, I1 and I2
1119 If we created two insns, return I2; otherwise return I3.
1120 Return 0 if the combination does not work. Then nothing is changed. */
1123 try_combine (i3, i2, i1)
1124 register rtx i3, i2, i1;
1126 /* New patterns for I3 and I3, respectively. */
1127 rtx newpat, newi2pat = 0;
1128 /* Indicates need to preserve SET in I1 or I2 in I3 if it is not dead. */
1129 int added_sets_1, added_sets_2;
1130 /* Total number of SETs to put into I3. */
1132 /* Nonzero is I2's body now appears in I3. */
1134 /* INSN_CODEs for new I3, new I2, and user of condition code. */
1135 int insn_code_number, i2_code_number, other_code_number;
1136 /* Contains I3 if the destination of I3 is used in its source, which means
1137 that the old life of I3 is being killed. If that usage is placed into
1138 I2 and not in I3, a REG_DEAD note must be made. */
1139 rtx i3dest_killed = 0;
1140 /* SET_DEST and SET_SRC of I2 and I1. */
1141 rtx i2dest, i2src, i1dest = 0, i1src = 0;
1142 /* PATTERN (I2), or a copy of it in certain cases. */
1144 /* Indicates if I2DEST or I1DEST is in I2SRC or I1_SRC. */
1145 int i2dest_in_i2src, i1dest_in_i1src = 0, i2dest_in_i1src = 0;
1146 int i1_feeds_i3 = 0;
1147 /* Notes that must be added to REG_NOTES in I3 and I2. */
1148 rtx new_i3_notes, new_i2_notes;
1155 /* If any of I1, I2, and I3 isn't really an insn, we can't do anything.
1156 This can occur when flow deletes an insn that it has merged into an
1157 auto-increment address. We also can't do anything if I3 has a
1158 REG_LIBCALL note since we don't want to disrupt the contiguity of a
1161 if (GET_RTX_CLASS (GET_CODE (i3)) != 'i'
1162 || GET_RTX_CLASS (GET_CODE (i2)) != 'i'
1163 || (i1 && GET_RTX_CLASS (GET_CODE (i1)) != 'i')
1164 || find_reg_note (i3, REG_LIBCALL, NULL_RTX))
1169 undobuf.num_undo = previous_num_undos = 0;
1170 undobuf.other_insn = 0;
1172 /* Save the current high-water-mark so we can free storage if we didn't
1173 accept this combination. */
1174 undobuf.storage = (char *) oballoc (0);
1176 /* If I1 and I2 both feed I3, they can be in any order. To simplify the
1177 code below, set I1 to be the earlier of the two insns. */
1178 if (i1 && INSN_CUID (i1) > INSN_CUID (i2))
1179 temp = i1, i1 = i2, i2 = temp;
1181 /* First check for one important special-case that the code below will
1182 not handle. Namely, the case where I1 is zero, I2 has multiple sets,
1183 and I3 is a SET whose SET_SRC is a SET_DEST in I2. In that case,
1184 we may be able to replace that destination with the destination of I3.
1185 This occurs in the common code where we compute both a quotient and
1186 remainder into a structure, in which case we want to do the computation
1187 directly into the structure to avoid register-register copies.
1189 We make very conservative checks below and only try to handle the
1190 most common cases of this. For example, we only handle the case
1191 where I2 and I3 are adjacent to avoid making difficult register
1194 if (i1 == 0 && GET_CODE (i3) == INSN && GET_CODE (PATTERN (i3)) == SET
1195 && GET_CODE (SET_SRC (PATTERN (i3))) == REG
1196 && REGNO (SET_SRC (PATTERN (i3))) >= FIRST_PSEUDO_REGISTER
1197 #ifdef SMALL_REGISTER_CLASSES
1198 && (GET_CODE (SET_DEST (PATTERN (i3))) != REG
1199 || REGNO (SET_DEST (PATTERN (i3))) >= FIRST_PSEUDO_REGISTER)
1201 && find_reg_note (i3, REG_DEAD, SET_SRC (PATTERN (i3)))
1202 && GET_CODE (PATTERN (i2)) == PARALLEL
1203 && ! side_effects_p (SET_DEST (PATTERN (i3)))
1204 /* If the dest of I3 is a ZERO_EXTRACT or STRICT_LOW_PART, the code
1205 below would need to check what is inside (and reg_overlap_mentioned_p
1206 doesn't support those codes anyway). Don't allow those destinations;
1207 the resulting insn isn't likely to be recognized anyway. */
1208 && GET_CODE (SET_DEST (PATTERN (i3))) != ZERO_EXTRACT
1209 && GET_CODE (SET_DEST (PATTERN (i3))) != STRICT_LOW_PART
1210 && ! reg_overlap_mentioned_p (SET_SRC (PATTERN (i3)),
1211 SET_DEST (PATTERN (i3)))
1212 && next_real_insn (i2) == i3)
1214 rtx p2 = PATTERN (i2);
1216 /* Make sure that the destination of I3,
1217 which we are going to substitute into one output of I2,
1218 is not used within another output of I2. We must avoid making this:
1219 (parallel [(set (mem (reg 69)) ...)
1220 (set (reg 69) ...)])
1221 which is not well-defined as to order of actions.
1222 (Besides, reload can't handle output reloads for this.)
1224 The problem can also happen if the dest of I3 is a memory ref,
1225 if another dest in I2 is an indirect memory ref. */
1226 for (i = 0; i < XVECLEN (p2, 0); i++)
1227 if (GET_CODE (XVECEXP (p2, 0, i)) == SET
1228 && reg_overlap_mentioned_p (SET_DEST (PATTERN (i3)),
1229 SET_DEST (XVECEXP (p2, 0, i))))
1232 if (i == XVECLEN (p2, 0))
1233 for (i = 0; i < XVECLEN (p2, 0); i++)
1234 if (SET_DEST (XVECEXP (p2, 0, i)) == SET_SRC (PATTERN (i3)))
1239 subst_low_cuid = INSN_CUID (i2);
1242 i2dest = SET_SRC (PATTERN (i3));
1244 /* Replace the dest in I2 with our dest and make the resulting
1245 insn the new pattern for I3. Then skip to where we
1246 validate the pattern. Everything was set up above. */
1247 SUBST (SET_DEST (XVECEXP (p2, 0, i)),
1248 SET_DEST (PATTERN (i3)));
1251 goto validate_replacement;
1256 /* If we have no I1 and I2 looks like:
1257 (parallel [(set (reg:CC X) (compare:CC OP (const_int 0)))
1259 make up a dummy I1 that is
1262 (set (reg:CC X) (compare:CC Y (const_int 0)))
1264 (We can ignore any trailing CLOBBERs.)
1266 This undoes a previous combination and allows us to match a branch-and-
1269 if (i1 == 0 && GET_CODE (PATTERN (i2)) == PARALLEL
1270 && XVECLEN (PATTERN (i2), 0) >= 2
1271 && GET_CODE (XVECEXP (PATTERN (i2), 0, 0)) == SET
1272 && (GET_MODE_CLASS (GET_MODE (SET_DEST (XVECEXP (PATTERN (i2), 0, 0))))
1274 && GET_CODE (SET_SRC (XVECEXP (PATTERN (i2), 0, 0))) == COMPARE
1275 && XEXP (SET_SRC (XVECEXP (PATTERN (i2), 0, 0)), 1) == const0_rtx
1276 && GET_CODE (XVECEXP (PATTERN (i2), 0, 1)) == SET
1277 && GET_CODE (SET_DEST (XVECEXP (PATTERN (i2), 0, 1))) == REG
1278 && rtx_equal_p (XEXP (SET_SRC (XVECEXP (PATTERN (i2), 0, 0)), 0),
1279 SET_SRC (XVECEXP (PATTERN (i2), 0, 1))))
1281 for (i = XVECLEN (PATTERN (i2), 0) - 1; i >= 2; i--)
1282 if (GET_CODE (XVECEXP (PATTERN (i2), 0, i)) != CLOBBER)
1287 /* We make I1 with the same INSN_UID as I2. This gives it
1288 the same INSN_CUID for value tracking. Our fake I1 will
1289 never appear in the insn stream so giving it the same INSN_UID
1290 as I2 will not cause a problem. */
1292 i1 = gen_rtx (INSN, VOIDmode, INSN_UID (i2), 0, i2,
1293 XVECEXP (PATTERN (i2), 0, 1), -1, 0, 0);
1295 SUBST (PATTERN (i2), XVECEXP (PATTERN (i2), 0, 0));
1296 SUBST (XEXP (SET_SRC (PATTERN (i2)), 0),
1297 SET_DEST (PATTERN (i1)));
1302 /* Verify that I2 and I1 are valid for combining. */
1303 if (! can_combine_p (i2, i3, i1, NULL_RTX, &i2dest, &i2src)
1304 || (i1 && ! can_combine_p (i1, i3, NULL_RTX, i2, &i1dest, &i1src)))
1310 /* Record whether I2DEST is used in I2SRC and similarly for the other
1311 cases. Knowing this will help in register status updating below. */
1312 i2dest_in_i2src = reg_overlap_mentioned_p (i2dest, i2src);
1313 i1dest_in_i1src = i1 && reg_overlap_mentioned_p (i1dest, i1src);
1314 i2dest_in_i1src = i1 && reg_overlap_mentioned_p (i2dest, i1src);
1316 /* See if I1 directly feeds into I3. It does if I1DEST is not used
1318 i1_feeds_i3 = i1 && ! reg_overlap_mentioned_p (i1dest, i2src);
1320 /* Ensure that I3's pattern can be the destination of combines. */
1321 if (! combinable_i3pat (i3, &PATTERN (i3), i2dest, i1dest,
1322 i1 && i2dest_in_i1src && i1_feeds_i3,
1329 /* If I3 has an inc, then give up if I1 or I2 uses the reg that is inc'd.
1330 We used to do this EXCEPT in one case: I3 has a post-inc in an
1331 output operand. However, that exception can give rise to insns like
1333 which is a famous insn on the PDP-11 where the value of r3 used as the
1334 source was model-dependent. Avoid this sort of thing. */
1337 if (!(GET_CODE (PATTERN (i3)) == SET
1338 && GET_CODE (SET_SRC (PATTERN (i3))) == REG
1339 && GET_CODE (SET_DEST (PATTERN (i3))) == MEM
1340 && (GET_CODE (XEXP (SET_DEST (PATTERN (i3)), 0)) == POST_INC
1341 || GET_CODE (XEXP (SET_DEST (PATTERN (i3)), 0)) == POST_DEC)))
1342 /* It's not the exception. */
1345 for (link = REG_NOTES (i3); link; link = XEXP (link, 1))
1346 if (REG_NOTE_KIND (link) == REG_INC
1347 && (reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i2))
1349 && reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i1)))))
1356 /* See if the SETs in I1 or I2 need to be kept around in the merged
1357 instruction: whenever the value set there is still needed past I3.
1358 For the SETs in I2, this is easy: we see if I2DEST dies or is set in I3.
1360 For the SET in I1, we have two cases: If I1 and I2 independently
1361 feed into I3, the set in I1 needs to be kept around if I1DEST dies
1362 or is set in I3. Otherwise (if I1 feeds I2 which feeds I3), the set
1363 in I1 needs to be kept around unless I1DEST dies or is set in either
1364 I2 or I3. We can distinguish these cases by seeing if I2SRC mentions
1365 I1DEST. If so, we know I1 feeds into I2. */
1367 added_sets_2 = ! dead_or_set_p (i3, i2dest);
1370 = i1 && ! (i1_feeds_i3 ? dead_or_set_p (i3, i1dest)
1371 : (dead_or_set_p (i3, i1dest) || dead_or_set_p (i2, i1dest)));
1373 /* If the set in I2 needs to be kept around, we must make a copy of
1374 PATTERN (I2), so that when we substitute I1SRC for I1DEST in
1375 PATTERN (I2), we are only substituting for the original I1DEST, not into
1376 an already-substituted copy. This also prevents making self-referential
1377 rtx. If I2 is a PARALLEL, we just need the piece that assigns I2SRC to
1380 i2pat = (GET_CODE (PATTERN (i2)) == PARALLEL
1381 ? gen_rtx (SET, VOIDmode, i2dest, i2src)
1385 i2pat = copy_rtx (i2pat);
1389 /* Substitute in the latest insn for the regs set by the earlier ones. */
1391 maxreg = max_reg_num ();
1395 /* It is possible that the source of I2 or I1 may be performing an
1396 unneeded operation, such as a ZERO_EXTEND of something that is known
1397 to have the high part zero. Handle that case by letting subst look at
1398 the innermost one of them.
1400 Another way to do this would be to have a function that tries to
1401 simplify a single insn instead of merging two or more insns. We don't
1402 do this because of the potential of infinite loops and because
1403 of the potential extra memory required. However, doing it the way
1404 we are is a bit of a kludge and doesn't catch all cases.
1406 But only do this if -fexpensive-optimizations since it slows things down
1407 and doesn't usually win. */
1409 if (flag_expensive_optimizations)
1411 /* Pass pc_rtx so no substitutions are done, just simplifications.
1412 The cases that we are interested in here do not involve the few
1413 cases were is_replaced is checked. */
1416 subst_low_cuid = INSN_CUID (i1);
1417 i1src = subst (i1src, pc_rtx, pc_rtx, 0, 0);
1421 subst_low_cuid = INSN_CUID (i2);
1422 i2src = subst (i2src, pc_rtx, pc_rtx, 0, 0);
1425 previous_num_undos = undobuf.num_undo;
1429 /* Many machines that don't use CC0 have insns that can both perform an
1430 arithmetic operation and set the condition code. These operations will
1431 be represented as a PARALLEL with the first element of the vector
1432 being a COMPARE of an arithmetic operation with the constant zero.
1433 The second element of the vector will set some pseudo to the result
1434 of the same arithmetic operation. If we simplify the COMPARE, we won't
1435 match such a pattern and so will generate an extra insn. Here we test
1436 for this case, where both the comparison and the operation result are
1437 needed, and make the PARALLEL by just replacing I2DEST in I3SRC with
1438 I2SRC. Later we will make the PARALLEL that contains I2. */
1440 if (i1 == 0 && added_sets_2 && GET_CODE (PATTERN (i3)) == SET
1441 && GET_CODE (SET_SRC (PATTERN (i3))) == COMPARE
1442 && XEXP (SET_SRC (PATTERN (i3)), 1) == const0_rtx
1443 && rtx_equal_p (XEXP (SET_SRC (PATTERN (i3)), 0), i2dest))
1446 enum machine_mode compare_mode;
1448 newpat = PATTERN (i3);
1449 SUBST (XEXP (SET_SRC (newpat), 0), i2src);
1453 #ifdef EXTRA_CC_MODES
1454 /* See if a COMPARE with the operand we substituted in should be done
1455 with the mode that is currently being used. If not, do the same
1456 processing we do in `subst' for a SET; namely, if the destination
1457 is used only once, try to replace it with a register of the proper
1458 mode and also replace the COMPARE. */
1459 if (undobuf.other_insn == 0
1460 && (cc_use = find_single_use (SET_DEST (newpat), i3,
1461 &undobuf.other_insn))
1462 && ((compare_mode = SELECT_CC_MODE (GET_CODE (*cc_use),
1464 != GET_MODE (SET_DEST (newpat))))
1466 int regno = REGNO (SET_DEST (newpat));
1467 rtx new_dest = gen_rtx (REG, compare_mode, regno);
1469 if (regno < FIRST_PSEUDO_REGISTER
1470 || (reg_n_sets[regno] == 1 && ! added_sets_2
1471 && ! REG_USERVAR_P (SET_DEST (newpat))))
1473 if (regno >= FIRST_PSEUDO_REGISTER)
1474 SUBST (regno_reg_rtx[regno], new_dest);
1476 SUBST (SET_DEST (newpat), new_dest);
1477 SUBST (XEXP (*cc_use, 0), new_dest);
1478 SUBST (SET_SRC (newpat),
1479 gen_rtx_combine (COMPARE, compare_mode,
1480 i2src, const0_rtx));
1483 undobuf.other_insn = 0;
1490 n_occurrences = 0; /* `subst' counts here */
1492 /* If I1 feeds into I2 (not into I3) and I1DEST is in I1SRC, we
1493 need to make a unique copy of I2SRC each time we substitute it
1494 to avoid self-referential rtl. */
1496 subst_low_cuid = INSN_CUID (i2);
1497 newpat = subst (PATTERN (i3), i2dest, i2src, 0,
1498 ! i1_feeds_i3 && i1dest_in_i1src);
1499 previous_num_undos = undobuf.num_undo;
1501 /* Record whether i2's body now appears within i3's body. */
1502 i2_is_used = n_occurrences;
1505 /* If we already got a failure, don't try to do more. Otherwise,
1506 try to substitute in I1 if we have it. */
1508 if (i1 && GET_CODE (newpat) != CLOBBER)
1510 /* Before we can do this substitution, we must redo the test done
1511 above (see detailed comments there) that ensures that I1DEST
1512 isn't mentioned in any SETs in NEWPAT that are field assignments. */
1514 if (! combinable_i3pat (NULL_RTX, &newpat, i1dest, NULL_RTX,
1522 subst_low_cuid = INSN_CUID (i1);
1523 newpat = subst (newpat, i1dest, i1src, 0, 0);
1524 previous_num_undos = undobuf.num_undo;
1527 /* Fail if an autoincrement side-effect has been duplicated. Be careful
1528 to count all the ways that I2SRC and I1SRC can be used. */
1529 if ((FIND_REG_INC_NOTE (i2, NULL_RTX) != 0
1530 && i2_is_used + added_sets_2 > 1)
1531 || (i1 != 0 && FIND_REG_INC_NOTE (i1, NULL_RTX) != 0
1532 && (n_occurrences + added_sets_1 + (added_sets_2 && ! i1_feeds_i3)
1534 /* Fail if we tried to make a new register (we used to abort, but there's
1535 really no reason to). */
1536 || max_reg_num () != maxreg
1537 /* Fail if we couldn't do something and have a CLOBBER. */
1538 || GET_CODE (newpat) == CLOBBER)
1544 /* If the actions of the earlier insns must be kept
1545 in addition to substituting them into the latest one,
1546 we must make a new PARALLEL for the latest insn
1547 to hold additional the SETs. */
1549 if (added_sets_1 || added_sets_2)
1553 if (GET_CODE (newpat) == PARALLEL)
1555 rtvec old = XVEC (newpat, 0);
1556 total_sets = XVECLEN (newpat, 0) + added_sets_1 + added_sets_2;
1557 newpat = gen_rtx (PARALLEL, VOIDmode, rtvec_alloc (total_sets));
1558 bcopy (&old->elem[0], &XVECEXP (newpat, 0, 0),
1559 sizeof (old->elem[0]) * old->num_elem);
1564 total_sets = 1 + added_sets_1 + added_sets_2;
1565 newpat = gen_rtx (PARALLEL, VOIDmode, rtvec_alloc (total_sets));
1566 XVECEXP (newpat, 0, 0) = old;
1570 XVECEXP (newpat, 0, --total_sets)
1571 = (GET_CODE (PATTERN (i1)) == PARALLEL
1572 ? gen_rtx (SET, VOIDmode, i1dest, i1src) : PATTERN (i1));
1576 /* If there is no I1, use I2's body as is. We used to also not do
1577 the subst call below if I2 was substituted into I3,
1578 but that could lose a simplification. */
1580 XVECEXP (newpat, 0, --total_sets) = i2pat;
1582 /* See comment where i2pat is assigned. */
1583 XVECEXP (newpat, 0, --total_sets)
1584 = subst (i2pat, i1dest, i1src, 0, 0);
1588 /* We come here when we are replacing a destination in I2 with the
1589 destination of I3. */
1590 validate_replacement:
1592 /* Is the result of combination a valid instruction? */
1593 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
1595 /* If the result isn't valid, see if it is a PARALLEL of two SETs where
1596 the second SET's destination is a register that is unused. In that case,
1597 we just need the first SET. This can occur when simplifying a divmod
1598 insn. We *must* test for this case here because the code below that
1599 splits two independent SETs doesn't handle this case correctly when it
1600 updates the register status. Also check the case where the first
1601 SET's destination is unused. That would not cause incorrect code, but
1602 does cause an unneeded insn to remain. */
1604 if (insn_code_number < 0 && GET_CODE (newpat) == PARALLEL
1605 && XVECLEN (newpat, 0) == 2
1606 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
1607 && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
1608 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) == REG
1609 && find_reg_note (i3, REG_UNUSED, SET_DEST (XVECEXP (newpat, 0, 1)))
1610 && ! side_effects_p (SET_SRC (XVECEXP (newpat, 0, 1)))
1611 && asm_noperands (newpat) < 0)
1613 newpat = XVECEXP (newpat, 0, 0);
1614 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
1617 else if (insn_code_number < 0 && GET_CODE (newpat) == PARALLEL
1618 && XVECLEN (newpat, 0) == 2
1619 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
1620 && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
1621 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) == REG
1622 && find_reg_note (i3, REG_UNUSED, SET_DEST (XVECEXP (newpat, 0, 0)))
1623 && ! side_effects_p (SET_SRC (XVECEXP (newpat, 0, 0)))
1624 && asm_noperands (newpat) < 0)
1626 newpat = XVECEXP (newpat, 0, 1);
1627 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
1630 /* See if this is an XOR. If so, perhaps the problem is that the
1631 constant is out of range. Replace it with a complemented XOR with
1632 a complemented constant; it might be in range. */
1634 else if (insn_code_number < 0 && GET_CODE (newpat) == SET
1635 && GET_CODE (SET_SRC (newpat)) == XOR
1636 && GET_CODE (XEXP (SET_SRC (newpat), 1)) == CONST_INT
1637 && ((temp = simplify_unary_operation (NOT,
1638 GET_MODE (SET_SRC (newpat)),
1639 XEXP (SET_SRC (newpat), 1),
1640 GET_MODE (SET_SRC (newpat))))
1643 enum machine_mode i_mode = GET_MODE (SET_SRC (newpat));
1645 = gen_rtx_combine (SET, VOIDmode, SET_DEST (newpat),
1646 gen_unary (NOT, i_mode,
1647 gen_binary (XOR, i_mode,
1648 XEXP (SET_SRC (newpat), 0),
1651 insn_code_number = recog_for_combine (&pat, i3, &new_i3_notes);
1652 if (insn_code_number >= 0)
1656 /* If we were combining three insns and the result is a simple SET
1657 with no ASM_OPERANDS that wasn't recognized, try to split it into two
1658 insns. There are two ways to do this. It can be split using a
1659 machine-specific method (like when you have an addition of a large
1660 constant) or by combine in the function find_split_point. */
1662 if (i1 && insn_code_number < 0 && GET_CODE (newpat) == SET
1663 && asm_noperands (newpat) < 0)
1665 rtx m_split, *split;
1666 rtx ni2dest = i2dest;
1668 /* See if the MD file can split NEWPAT. If it can't, see if letting it
1669 use I2DEST as a scratch register will help. In the latter case,
1670 convert I2DEST to the mode of the source of NEWPAT if we can. */
1672 m_split = split_insns (newpat, i3);
1674 /* We can only use I2DEST as a scratch reg if it doesn't overlap any
1675 inputs of NEWPAT. */
1677 /* ??? If I2DEST is not safe, and I1DEST exists, then it would be
1678 possible to try that as a scratch reg. This would require adding
1679 more code to make it work though. */
1681 if (m_split == 0 && ! reg_overlap_mentioned_p (ni2dest, newpat))
1683 /* If I2DEST is a hard register or the only use of a pseudo,
1684 we can change its mode. */
1685 if (GET_MODE (SET_DEST (newpat)) != GET_MODE (i2dest)
1686 && GET_MODE (SET_DEST (newpat)) != VOIDmode
1687 && GET_CODE (i2dest) == REG
1688 && (REGNO (i2dest) < FIRST_PSEUDO_REGISTER
1689 || (reg_n_sets[REGNO (i2dest)] == 1 && ! added_sets_2
1690 && ! REG_USERVAR_P (i2dest))))
1691 ni2dest = gen_rtx (REG, GET_MODE (SET_DEST (newpat)),
1694 m_split = split_insns (gen_rtx (PARALLEL, VOIDmode,
1695 gen_rtvec (2, newpat,
1702 if (m_split && GET_CODE (m_split) == SEQUENCE
1703 && XVECLEN (m_split, 0) == 2
1704 && (next_real_insn (i2) == i3
1705 || ! use_crosses_set_p (PATTERN (XVECEXP (m_split, 0, 0)),
1709 rtx newi3pat = PATTERN (XVECEXP (m_split, 0, 1));
1710 newi2pat = PATTERN (XVECEXP (m_split, 0, 0));
1712 i3set = single_set (XVECEXP (m_split, 0, 1));
1713 i2set = single_set (XVECEXP (m_split, 0, 0));
1715 /* In case we changed the mode of I2DEST, replace it in the
1716 pseudo-register table here. We can't do it above in case this
1717 code doesn't get executed and we do a split the other way. */
1719 if (REGNO (i2dest) >= FIRST_PSEUDO_REGISTER)
1720 SUBST (regno_reg_rtx[REGNO (i2dest)], ni2dest);
1722 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
1724 /* If I2 or I3 has multiple SETs, we won't know how to track
1725 register status, so don't use these insns. */
1727 if (i2_code_number >= 0 && i2set && i3set)
1728 insn_code_number = recog_for_combine (&newi3pat, i3,
1731 if (insn_code_number >= 0)
1734 /* It is possible that both insns now set the destination of I3.
1735 If so, we must show an extra use of it. */
1737 if (insn_code_number >= 0 && GET_CODE (SET_DEST (i3set)) == REG
1738 && GET_CODE (SET_DEST (i2set)) == REG
1739 && REGNO (SET_DEST (i3set)) == REGNO (SET_DEST (i2set)))
1740 reg_n_sets[REGNO (SET_DEST (i2set))]++;
1743 /* If we can split it and use I2DEST, go ahead and see if that
1744 helps things be recognized. Verify that none of the registers
1745 are set between I2 and I3. */
1746 if (insn_code_number < 0 && (split = find_split_point (&newpat, i3)) != 0
1748 && GET_CODE (i2dest) == REG
1750 /* We need I2DEST in the proper mode. If it is a hard register
1751 or the only use of a pseudo, we can change its mode. */
1752 && (GET_MODE (*split) == GET_MODE (i2dest)
1753 || GET_MODE (*split) == VOIDmode
1754 || REGNO (i2dest) < FIRST_PSEUDO_REGISTER
1755 || (reg_n_sets[REGNO (i2dest)] == 1 && ! added_sets_2
1756 && ! REG_USERVAR_P (i2dest)))
1757 && (next_real_insn (i2) == i3
1758 || ! use_crosses_set_p (*split, INSN_CUID (i2)))
1759 /* We can't overwrite I2DEST if its value is still used by
1761 && ! reg_referenced_p (i2dest, newpat))
1763 rtx newdest = i2dest;
1765 /* Get NEWDEST as a register in the proper mode. We have already
1766 validated that we can do this. */
1767 if (GET_MODE (i2dest) != GET_MODE (*split)
1768 && GET_MODE (*split) != VOIDmode)
1770 newdest = gen_rtx (REG, GET_MODE (*split), REGNO (i2dest));
1772 if (REGNO (i2dest) >= FIRST_PSEUDO_REGISTER)
1773 SUBST (regno_reg_rtx[REGNO (i2dest)], newdest);
1776 /* If *SPLIT is a (mult FOO (const_int pow2)), convert it to
1777 an ASHIFT. This can occur if it was inside a PLUS and hence
1778 appeared to be a memory address. This is a kludge. */
1779 if (GET_CODE (*split) == MULT
1780 && GET_CODE (XEXP (*split, 1)) == CONST_INT
1781 && (i = exact_log2 (INTVAL (XEXP (*split, 1)))) >= 0)
1782 SUBST (*split, gen_rtx_combine (ASHIFT, GET_MODE (*split),
1783 XEXP (*split, 0), GEN_INT (i)));
1785 #ifdef INSN_SCHEDULING
1786 /* If *SPLIT is a paradoxical SUBREG, when we split it, it should
1787 be written as a ZERO_EXTEND. */
1788 if (GET_CODE (*split) == SUBREG
1789 && GET_CODE (SUBREG_REG (*split)) == MEM)
1790 SUBST (*split, gen_rtx_combine (ZERO_EXTEND, GET_MODE (*split),
1794 newi2pat = gen_rtx_combine (SET, VOIDmode, newdest, *split);
1795 SUBST (*split, newdest);
1796 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
1797 if (i2_code_number >= 0)
1798 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
1802 /* Check for a case where we loaded from memory in a narrow mode and
1803 then sign extended it, but we need both registers. In that case,
1804 we have a PARALLEL with both loads from the same memory location.
1805 We can split this into a load from memory followed by a register-register
1806 copy. This saves at least one insn, more if register allocation can
1807 eliminate the copy. */
1809 else if (i1 && insn_code_number < 0 && asm_noperands (newpat) < 0
1810 && GET_CODE (newpat) == PARALLEL
1811 && XVECLEN (newpat, 0) == 2
1812 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
1813 && GET_CODE (SET_SRC (XVECEXP (newpat, 0, 0))) == SIGN_EXTEND
1814 && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
1815 && rtx_equal_p (SET_SRC (XVECEXP (newpat, 0, 1)),
1816 XEXP (SET_SRC (XVECEXP (newpat, 0, 0)), 0))
1817 && ! use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)),
1819 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT
1820 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART
1821 && ! reg_overlap_mentioned_p (SET_DEST (XVECEXP (newpat, 0, 1)),
1822 SET_SRC (XVECEXP (newpat, 0, 1)))
1823 && ! find_reg_note (i3, REG_UNUSED,
1824 SET_DEST (XVECEXP (newpat, 0, 0))))
1828 newi2pat = XVECEXP (newpat, 0, 0);
1829 ni2dest = SET_DEST (XVECEXP (newpat, 0, 0));
1830 newpat = XVECEXP (newpat, 0, 1);
1831 SUBST (SET_SRC (newpat),
1832 gen_lowpart_for_combine (GET_MODE (SET_SRC (newpat)), ni2dest));
1833 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
1834 if (i2_code_number >= 0)
1835 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
1837 if (insn_code_number >= 0)
1842 /* If we will be able to accept this, we have made a change to the
1843 destination of I3. This can invalidate a LOG_LINKS pointing
1844 to I3. No other part of combine.c makes such a transformation.
1846 The new I3 will have a destination that was previously the
1847 destination of I1 or I2 and which was used in i2 or I3. Call
1848 distribute_links to make a LOG_LINK from the next use of
1849 that destination. */
1851 PATTERN (i3) = newpat;
1852 distribute_links (gen_rtx (INSN_LIST, VOIDmode, i3, NULL_RTX));
1854 /* I3 now uses what used to be its destination and which is
1855 now I2's destination. That means we need a LOG_LINK from
1856 I3 to I2. But we used to have one, so we still will.
1858 However, some later insn might be using I2's dest and have
1859 a LOG_LINK pointing at I3. We must remove this link.
1860 The simplest way to remove the link is to point it at I1,
1861 which we know will be a NOTE. */
1863 for (insn = NEXT_INSN (i3);
1864 insn && GET_CODE (insn) != CODE_LABEL
1865 && GET_CODE (PREV_INSN (insn)) != JUMP_INSN;
1866 insn = NEXT_INSN (insn))
1868 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
1869 && reg_referenced_p (ni2dest, PATTERN (insn)))
1871 for (link = LOG_LINKS (insn); link;
1872 link = XEXP (link, 1))
1873 if (XEXP (link, 0) == i3)
1874 XEXP (link, 0) = i1;
1882 /* Similarly, check for a case where we have a PARALLEL of two independent
1883 SETs but we started with three insns. In this case, we can do the sets
1884 as two separate insns. This case occurs when some SET allows two
1885 other insns to combine, but the destination of that SET is still live. */
1887 else if (i1 && insn_code_number < 0 && asm_noperands (newpat) < 0
1888 && GET_CODE (newpat) == PARALLEL
1889 && XVECLEN (newpat, 0) == 2
1890 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
1891 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != ZERO_EXTRACT
1892 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != STRICT_LOW_PART
1893 && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
1894 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT
1895 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART
1896 && ! use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)),
1898 /* Don't pass sets with (USE (MEM ...)) dests to the following. */
1899 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != USE
1900 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != USE
1901 && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 1)),
1902 XVECEXP (newpat, 0, 0))
1903 && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 0)),
1904 XVECEXP (newpat, 0, 1)))
1906 newi2pat = XVECEXP (newpat, 0, 1);
1907 newpat = XVECEXP (newpat, 0, 0);
1909 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
1910 if (i2_code_number >= 0)
1911 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
1914 /* If it still isn't recognized, fail and change things back the way they
1916 if ((insn_code_number < 0
1917 /* Is the result a reasonable ASM_OPERANDS? */
1918 && (! check_asm_operands (newpat) || added_sets_1 || added_sets_2)))
1924 /* If we had to change another insn, make sure it is valid also. */
1925 if (undobuf.other_insn)
1927 rtx other_notes = REG_NOTES (undobuf.other_insn);
1928 rtx other_pat = PATTERN (undobuf.other_insn);
1929 rtx new_other_notes;
1932 other_code_number = recog_for_combine (&other_pat, undobuf.other_insn,
1935 if (other_code_number < 0 && ! check_asm_operands (other_pat))
1941 PATTERN (undobuf.other_insn) = other_pat;
1943 /* If any of the notes in OTHER_INSN were REG_UNUSED, ensure that they
1944 are still valid. Then add any non-duplicate notes added by
1945 recog_for_combine. */
1946 for (note = REG_NOTES (undobuf.other_insn); note; note = next)
1948 next = XEXP (note, 1);
1950 if (REG_NOTE_KIND (note) == REG_UNUSED
1951 && ! reg_set_p (XEXP (note, 0), PATTERN (undobuf.other_insn)))
1953 if (GET_CODE (XEXP (note, 0)) == REG)
1954 reg_n_deaths[REGNO (XEXP (note, 0))]--;
1956 remove_note (undobuf.other_insn, note);
1960 for (note = new_other_notes; note; note = XEXP (note, 1))
1961 if (GET_CODE (XEXP (note, 0)) == REG)
1962 reg_n_deaths[REGNO (XEXP (note, 0))]++;
1964 distribute_notes (new_other_notes, undobuf.other_insn,
1965 undobuf.other_insn, NULL_RTX, NULL_RTX, NULL_RTX);
1968 /* We now know that we can do this combination. Merge the insns and
1969 update the status of registers and LOG_LINKS. */
1972 rtx i3notes, i2notes, i1notes = 0;
1973 rtx i3links, i2links, i1links = 0;
1975 int all_adjacent = (next_real_insn (i2) == i3
1976 && (i1 == 0 || next_real_insn (i1) == i2));
1978 /* Compute which registers we expect to eliminate. */
1979 rtx elim_i2 = (newi2pat || i2dest_in_i2src || i2dest_in_i1src
1981 rtx elim_i1 = i1 == 0 || i1dest_in_i1src ? 0 : i1dest;
1983 /* Get the old REG_NOTES and LOG_LINKS from all our insns and
1985 i3notes = REG_NOTES (i3), i3links = LOG_LINKS (i3);
1986 i2notes = REG_NOTES (i2), i2links = LOG_LINKS (i2);
1988 i1notes = REG_NOTES (i1), i1links = LOG_LINKS (i1);
1990 /* Ensure that we do not have something that should not be shared but
1991 occurs multiple times in the new insns. Check this by first
1992 resetting all the `used' flags and then copying anything is shared. */
1994 reset_used_flags (i3notes);
1995 reset_used_flags (i2notes);
1996 reset_used_flags (i1notes);
1997 reset_used_flags (newpat);
1998 reset_used_flags (newi2pat);
1999 if (undobuf.other_insn)
2000 reset_used_flags (PATTERN (undobuf.other_insn));
2002 i3notes = copy_rtx_if_shared (i3notes);
2003 i2notes = copy_rtx_if_shared (i2notes);
2004 i1notes = copy_rtx_if_shared (i1notes);
2005 newpat = copy_rtx_if_shared (newpat);
2006 newi2pat = copy_rtx_if_shared (newi2pat);
2007 if (undobuf.other_insn)
2008 reset_used_flags (PATTERN (undobuf.other_insn));
2010 INSN_CODE (i3) = insn_code_number;
2011 PATTERN (i3) = newpat;
2012 if (undobuf.other_insn)
2013 INSN_CODE (undobuf.other_insn) = other_code_number;
2015 /* We had one special case above where I2 had more than one set and
2016 we replaced a destination of one of those sets with the destination
2017 of I3. In that case, we have to update LOG_LINKS of insns later
2018 in this basic block. Note that this (expensive) case is rare. */
2020 if (GET_CODE (PATTERN (i2)) == PARALLEL)
2021 for (i = 0; i < XVECLEN (PATTERN (i2), 0); i++)
2022 if (GET_CODE (SET_DEST (XVECEXP (PATTERN (i2), 0, i))) == REG
2023 && SET_DEST (XVECEXP (PATTERN (i2), 0, i)) != i2dest
2024 && ! find_reg_note (i2, REG_UNUSED,
2025 SET_DEST (XVECEXP (PATTERN (i2), 0, i))))
2029 for (insn = NEXT_INSN (i2); insn; insn = NEXT_INSN (insn))
2031 if (insn != i3 && GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2032 for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
2033 if (XEXP (link, 0) == i2)
2034 XEXP (link, 0) = i3;
2036 if (GET_CODE (insn) == CODE_LABEL
2037 || GET_CODE (insn) == JUMP_INSN)
2049 INSN_CODE (i2) = i2_code_number;
2050 PATTERN (i2) = newi2pat;
2054 PUT_CODE (i2, NOTE);
2055 NOTE_LINE_NUMBER (i2) = NOTE_INSN_DELETED;
2056 NOTE_SOURCE_FILE (i2) = 0;
2063 PUT_CODE (i1, NOTE);
2064 NOTE_LINE_NUMBER (i1) = NOTE_INSN_DELETED;
2065 NOTE_SOURCE_FILE (i1) = 0;
2068 /* Get death notes for everything that is now used in either I3 or
2069 I2 and used to die in a previous insn. */
2071 move_deaths (newpat, i1 ? INSN_CUID (i1) : INSN_CUID (i2), i3, &midnotes);
2073 move_deaths (newi2pat, INSN_CUID (i1), i2, &midnotes);
2075 /* Distribute all the LOG_LINKS and REG_NOTES from I1, I2, and I3. */
2077 distribute_notes (i3notes, i3, i3, newi2pat ? i2 : NULL_RTX,
2080 distribute_notes (i2notes, i2, i3, newi2pat ? i2 : NULL_RTX,
2083 distribute_notes (i1notes, i1, i3, newi2pat ? i2 : NULL_RTX,
2086 distribute_notes (midnotes, NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
2089 /* Distribute any notes added to I2 or I3 by recog_for_combine. We
2090 know these are REG_UNUSED and want them to go to the desired insn,
2091 so we always pass it as i3. We have not counted the notes in
2092 reg_n_deaths yet, so we need to do so now. */
2094 if (newi2pat && new_i2_notes)
2096 for (temp = new_i2_notes; temp; temp = XEXP (temp, 1))
2097 if (GET_CODE (XEXP (temp, 0)) == REG)
2098 reg_n_deaths[REGNO (XEXP (temp, 0))]++;
2100 distribute_notes (new_i2_notes, i2, i2, NULL_RTX, NULL_RTX, NULL_RTX);
2105 for (temp = new_i3_notes; temp; temp = XEXP (temp, 1))
2106 if (GET_CODE (XEXP (temp, 0)) == REG)
2107 reg_n_deaths[REGNO (XEXP (temp, 0))]++;
2109 distribute_notes (new_i3_notes, i3, i3, NULL_RTX, NULL_RTX, NULL_RTX);
2112 /* If I3DEST was used in I3SRC, it really died in I3. We may need to
2113 put a REG_DEAD note for it somewhere. Similarly for I2 and I1.
2114 Show an additional death due to the REG_DEAD note we make here. If
2115 we discard it in distribute_notes, we will decrement it again. */
2119 if (GET_CODE (i3dest_killed) == REG)
2120 reg_n_deaths[REGNO (i3dest_killed)]++;
2122 distribute_notes (gen_rtx (EXPR_LIST, REG_DEAD, i3dest_killed,
2124 NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
2125 NULL_RTX, NULL_RTX);
2128 /* For I2 and I1, we have to be careful. If NEWI2PAT exists and sets
2129 I2DEST or I1DEST, the death must be somewhere before I2, not I3. If
2130 we passed I3 in that case, it might delete I2. */
2132 if (i2dest_in_i2src)
2134 if (GET_CODE (i2dest) == REG)
2135 reg_n_deaths[REGNO (i2dest)]++;
2137 if (newi2pat && reg_set_p (i2dest, newi2pat))
2138 distribute_notes (gen_rtx (EXPR_LIST, REG_DEAD, i2dest, NULL_RTX),
2139 NULL_RTX, i2, NULL_RTX, NULL_RTX, NULL_RTX);
2141 distribute_notes (gen_rtx (EXPR_LIST, REG_DEAD, i2dest, NULL_RTX),
2142 NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
2143 NULL_RTX, NULL_RTX);
2146 if (i1dest_in_i1src)
2148 if (GET_CODE (i1dest) == REG)
2149 reg_n_deaths[REGNO (i1dest)]++;
2151 if (newi2pat && reg_set_p (i1dest, newi2pat))
2152 distribute_notes (gen_rtx (EXPR_LIST, REG_DEAD, i1dest, NULL_RTX),
2153 NULL_RTX, i2, NULL_RTX, NULL_RTX, NULL_RTX);
2155 distribute_notes (gen_rtx (EXPR_LIST, REG_DEAD, i1dest, NULL_RTX),
2156 NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
2157 NULL_RTX, NULL_RTX);
2160 distribute_links (i3links);
2161 distribute_links (i2links);
2162 distribute_links (i1links);
2164 if (GET_CODE (i2dest) == REG)
2167 rtx i2_insn = 0, i2_val = 0, set;
2169 /* The insn that used to set this register doesn't exist, and
2170 this life of the register may not exist either. See if one of
2171 I3's links points to an insn that sets I2DEST. If it does,
2172 that is now the last known value for I2DEST. If we don't update
2173 this and I2 set the register to a value that depended on its old
2174 contents, we will get confused. If this insn is used, thing
2175 will be set correctly in combine_instructions. */
2177 for (link = LOG_LINKS (i3); link; link = XEXP (link, 1))
2178 if ((set = single_set (XEXP (link, 0))) != 0
2179 && rtx_equal_p (i2dest, SET_DEST (set)))
2180 i2_insn = XEXP (link, 0), i2_val = SET_SRC (set);
2182 record_value_for_reg (i2dest, i2_insn, i2_val);
2184 /* If the reg formerly set in I2 died only once and that was in I3,
2185 zero its use count so it won't make `reload' do any work. */
2186 if (! added_sets_2 && newi2pat == 0)
2188 regno = REGNO (i2dest);
2189 reg_n_sets[regno]--;
2190 if (reg_n_sets[regno] == 0
2191 && ! (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
2192 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
2193 reg_n_refs[regno] = 0;
2197 if (i1 && GET_CODE (i1dest) == REG)
2200 rtx i1_insn = 0, i1_val = 0, set;
2202 for (link = LOG_LINKS (i3); link; link = XEXP (link, 1))
2203 if ((set = single_set (XEXP (link, 0))) != 0
2204 && rtx_equal_p (i1dest, SET_DEST (set)))
2205 i1_insn = XEXP (link, 0), i1_val = SET_SRC (set);
2207 record_value_for_reg (i1dest, i1_insn, i1_val);
2209 regno = REGNO (i1dest);
2212 reg_n_sets[regno]--;
2213 if (reg_n_sets[regno] == 0
2214 && ! (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
2215 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
2216 reg_n_refs[regno] = 0;
2220 /* Update reg_nonzero_bits et al for any changes that may have been made
2223 note_stores (newpat, set_nonzero_bits_and_sign_copies);
2225 note_stores (newi2pat, set_nonzero_bits_and_sign_copies);
2227 /* If I3 is now an unconditional jump, ensure that it has a
2228 BARRIER following it since it may have initially been a
2229 conditional jump. It may also be the last nonnote insn. */
2231 if ((GET_CODE (newpat) == RETURN || simplejump_p (i3))
2232 && ((temp = next_nonnote_insn (i3)) == NULL_RTX
2233 || GET_CODE (temp) != BARRIER))
2234 emit_barrier_after (i3);
2237 combine_successes++;
2239 return newi2pat ? i2 : i3;
2242 /* Undo all the modifications recorded in undobuf. */
2248 if (undobuf.num_undo > MAX_UNDO)
2249 undobuf.num_undo = MAX_UNDO;
2250 for (i = undobuf.num_undo - 1; i >= 0; i--)
2252 if (undobuf.undo[i].is_int)
2253 *undobuf.undo[i].where.i = undobuf.undo[i].old_contents.i;
2255 *undobuf.undo[i].where.rtx = undobuf.undo[i].old_contents.rtx;
2259 obfree (undobuf.storage);
2260 undobuf.num_undo = 0;
2263 /* Find the innermost point within the rtx at LOC, possibly LOC itself,
2264 where we have an arithmetic expression and return that point. LOC will
2267 try_combine will call this function to see if an insn can be split into
2271 find_split_point (loc, insn)
2276 enum rtx_code code = GET_CODE (x);
2278 int len = 0, pos, unsignedp;
2281 /* First special-case some codes. */
2285 #ifdef INSN_SCHEDULING
2286 /* If we are making a paradoxical SUBREG invalid, it becomes a split
2288 if (GET_CODE (SUBREG_REG (x)) == MEM)
2291 return find_split_point (&SUBREG_REG (x), insn);
2295 /* If we have (mem (const ..)) or (mem (symbol_ref ...)), split it
2296 using LO_SUM and HIGH. */
2297 if (GET_CODE (XEXP (x, 0)) == CONST
2298 || GET_CODE (XEXP (x, 0)) == SYMBOL_REF)
2301 gen_rtx_combine (LO_SUM, Pmode,
2302 gen_rtx_combine (HIGH, Pmode, XEXP (x, 0)),
2304 return &XEXP (XEXP (x, 0), 0);
2308 /* If we have a PLUS whose second operand is a constant and the
2309 address is not valid, perhaps will can split it up using
2310 the machine-specific way to split large constants. We use
2311 the first psuedo-reg (one of the virtual regs) as a placeholder;
2312 it will not remain in the result. */
2313 if (GET_CODE (XEXP (x, 0)) == PLUS
2314 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2315 && ! memory_address_p (GET_MODE (x), XEXP (x, 0)))
2317 rtx reg = regno_reg_rtx[FIRST_PSEUDO_REGISTER];
2318 rtx seq = split_insns (gen_rtx (SET, VOIDmode, reg, XEXP (x, 0)),
2321 /* This should have produced two insns, each of which sets our
2322 placeholder. If the source of the second is a valid address,
2323 we can make put both sources together and make a split point
2326 if (seq && XVECLEN (seq, 0) == 2
2327 && GET_CODE (XVECEXP (seq, 0, 0)) == INSN
2328 && GET_CODE (PATTERN (XVECEXP (seq, 0, 0))) == SET
2329 && SET_DEST (PATTERN (XVECEXP (seq, 0, 0))) == reg
2330 && ! reg_mentioned_p (reg,
2331 SET_SRC (PATTERN (XVECEXP (seq, 0, 0))))
2332 && GET_CODE (XVECEXP (seq, 0, 1)) == INSN
2333 && GET_CODE (PATTERN (XVECEXP (seq, 0, 1))) == SET
2334 && SET_DEST (PATTERN (XVECEXP (seq, 0, 1))) == reg
2335 && memory_address_p (GET_MODE (x),
2336 SET_SRC (PATTERN (XVECEXP (seq, 0, 1)))))
2338 rtx src1 = SET_SRC (PATTERN (XVECEXP (seq, 0, 0)));
2339 rtx src2 = SET_SRC (PATTERN (XVECEXP (seq, 0, 1)));
2341 /* Replace the placeholder in SRC2 with SRC1. If we can
2342 find where in SRC2 it was placed, that can become our
2343 split point and we can replace this address with SRC2.
2344 Just try two obvious places. */
2346 src2 = replace_rtx (src2, reg, src1);
2348 if (XEXP (src2, 0) == src1)
2349 split = &XEXP (src2, 0);
2350 else if (GET_RTX_FORMAT (GET_CODE (XEXP (src2, 0)))[0] == 'e'
2351 && XEXP (XEXP (src2, 0), 0) == src1)
2352 split = &XEXP (XEXP (src2, 0), 0);
2356 SUBST (XEXP (x, 0), src2);
2361 /* If that didn't work, perhaps the first operand is complex and
2362 needs to be computed separately, so make a split point there.
2363 This will occur on machines that just support REG + CONST
2364 and have a constant moved through some previous computation. */
2366 else if (GET_RTX_CLASS (GET_CODE (XEXP (XEXP (x, 0), 0))) != 'o'
2367 && ! (GET_CODE (XEXP (XEXP (x, 0), 0)) == SUBREG
2368 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (XEXP (x, 0), 0))))
2370 return &XEXP (XEXP (x, 0), 0);
2376 /* If SET_DEST is CC0 and SET_SRC is not an operand, a COMPARE, or a
2377 ZERO_EXTRACT, the most likely reason why this doesn't match is that
2378 we need to put the operand into a register. So split at that
2381 if (SET_DEST (x) == cc0_rtx
2382 && GET_CODE (SET_SRC (x)) != COMPARE
2383 && GET_CODE (SET_SRC (x)) != ZERO_EXTRACT
2384 && GET_RTX_CLASS (GET_CODE (SET_SRC (x))) != 'o'
2385 && ! (GET_CODE (SET_SRC (x)) == SUBREG
2386 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (SET_SRC (x)))) == 'o'))
2387 return &SET_SRC (x);
2390 /* See if we can split SET_SRC as it stands. */
2391 split = find_split_point (&SET_SRC (x), insn);
2392 if (split && split != &SET_SRC (x))
2395 /* See if this is a bitfield assignment with everything constant. If
2396 so, this is an IOR of an AND, so split it into that. */
2397 if (GET_CODE (SET_DEST (x)) == ZERO_EXTRACT
2398 && (GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0)))
2399 <= HOST_BITS_PER_WIDE_INT)
2400 && GET_CODE (XEXP (SET_DEST (x), 1)) == CONST_INT
2401 && GET_CODE (XEXP (SET_DEST (x), 2)) == CONST_INT
2402 && GET_CODE (SET_SRC (x)) == CONST_INT
2403 && ((INTVAL (XEXP (SET_DEST (x), 1))
2404 + INTVAL (XEXP (SET_DEST (x), 2)))
2405 <= GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0))))
2406 && ! side_effects_p (XEXP (SET_DEST (x), 0)))
2408 int pos = INTVAL (XEXP (SET_DEST (x), 2));
2409 int len = INTVAL (XEXP (SET_DEST (x), 1));
2410 int src = INTVAL (SET_SRC (x));
2411 rtx dest = XEXP (SET_DEST (x), 0);
2412 enum machine_mode mode = GET_MODE (dest);
2413 unsigned HOST_WIDE_INT mask = ((HOST_WIDE_INT) 1 << len) - 1;
2416 pos = GET_MODE_BITSIZE (mode) - len - pos;
2421 gen_binary (IOR, mode, dest, GEN_INT (src << pos)));
2424 gen_binary (IOR, mode,
2425 gen_binary (AND, mode, dest,
2426 GEN_INT (~ (mask << pos)
2427 & GET_MODE_MASK (mode))),
2428 GEN_INT (src << pos)));
2430 SUBST (SET_DEST (x), dest);
2432 split = find_split_point (&SET_SRC (x), insn);
2433 if (split && split != &SET_SRC (x))
2437 /* Otherwise, see if this is an operation that we can split into two.
2438 If so, try to split that. */
2439 code = GET_CODE (SET_SRC (x));
2444 /* If we are AND'ing with a large constant that is only a single
2445 bit and the result is only being used in a context where we
2446 need to know if it is zero or non-zero, replace it with a bit
2447 extraction. This will avoid the large constant, which might
2448 have taken more than one insn to make. If the constant were
2449 not a valid argument to the AND but took only one insn to make,
2450 this is no worse, but if it took more than one insn, it will
2453 if (GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
2454 && GET_CODE (XEXP (SET_SRC (x), 0)) == REG
2455 && (pos = exact_log2 (INTVAL (XEXP (SET_SRC (x), 1)))) >= 7
2456 && GET_CODE (SET_DEST (x)) == REG
2457 && (split = find_single_use (SET_DEST (x), insn, NULL_PTR)) != 0
2458 && (GET_CODE (*split) == EQ || GET_CODE (*split) == NE)
2459 && XEXP (*split, 0) == SET_DEST (x)
2460 && XEXP (*split, 1) == const0_rtx)
2463 make_extraction (GET_MODE (SET_DEST (x)),
2464 XEXP (SET_SRC (x), 0),
2465 pos, NULL_RTX, 1, 1, 0, 0));
2466 return find_split_point (loc, insn);
2471 inner = XEXP (SET_SRC (x), 0);
2473 len = GET_MODE_BITSIZE (GET_MODE (inner));
2479 if (GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
2480 && GET_CODE (XEXP (SET_SRC (x), 2)) == CONST_INT)
2482 inner = XEXP (SET_SRC (x), 0);
2483 len = INTVAL (XEXP (SET_SRC (x), 1));
2484 pos = INTVAL (XEXP (SET_SRC (x), 2));
2487 pos = GET_MODE_BITSIZE (GET_MODE (inner)) - len - pos;
2489 unsignedp = (code == ZERO_EXTRACT);
2494 if (len && pos >= 0 && pos + len <= GET_MODE_BITSIZE (GET_MODE (inner)))
2496 enum machine_mode mode = GET_MODE (SET_SRC (x));
2498 /* For unsigned, we have a choice of a shift followed by an
2499 AND or two shifts. Use two shifts for field sizes where the
2500 constant might be too large. We assume here that we can
2501 always at least get 8-bit constants in an AND insn, which is
2502 true for every current RISC. */
2504 if (unsignedp && len <= 8)
2509 gen_rtx_combine (LSHIFTRT, mode,
2510 gen_lowpart_for_combine (mode, inner),
2512 GEN_INT (((HOST_WIDE_INT) 1 << len) - 1)));
2514 split = find_split_point (&SET_SRC (x), insn);
2515 if (split && split != &SET_SRC (x))
2522 (unsignedp ? LSHIFTRT : ASHIFTRT, mode,
2523 gen_rtx_combine (ASHIFT, mode,
2524 gen_lowpart_for_combine (mode, inner),
2525 GEN_INT (GET_MODE_BITSIZE (mode)
2527 GEN_INT (GET_MODE_BITSIZE (mode) - len)));
2529 split = find_split_point (&SET_SRC (x), insn);
2530 if (split && split != &SET_SRC (x))
2535 /* See if this is a simple operation with a constant as the second
2536 operand. It might be that this constant is out of range and hence
2537 could be used as a split point. */
2538 if ((GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '2'
2539 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == 'c'
2540 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '<')
2541 && CONSTANT_P (XEXP (SET_SRC (x), 1))
2542 && (GET_RTX_CLASS (GET_CODE (XEXP (SET_SRC (x), 0))) == 'o'
2543 || (GET_CODE (XEXP (SET_SRC (x), 0)) == SUBREG
2544 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (SET_SRC (x), 0))))
2546 return &XEXP (SET_SRC (x), 1);
2548 /* Finally, see if this is a simple operation with its first operand
2549 not in a register. The operation might require this operand in a
2550 register, so return it as a split point. We can always do this
2551 because if the first operand were another operation, we would have
2552 already found it as a split point. */
2553 if ((GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '2'
2554 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == 'c'
2555 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '<'
2556 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '1')
2557 && ! register_operand (XEXP (SET_SRC (x), 0), VOIDmode))
2558 return &XEXP (SET_SRC (x), 0);
2564 /* We write NOR as (and (not A) (not B)), but if we don't have a NOR,
2565 it is better to write this as (not (ior A B)) so we can split it.
2566 Similarly for IOR. */
2567 if (GET_CODE (XEXP (x, 0)) == NOT && GET_CODE (XEXP (x, 1)) == NOT)
2570 gen_rtx_combine (NOT, GET_MODE (x),
2571 gen_rtx_combine (code == IOR ? AND : IOR,
2573 XEXP (XEXP (x, 0), 0),
2574 XEXP (XEXP (x, 1), 0))));
2575 return find_split_point (loc, insn);
2578 /* Many RISC machines have a large set of logical insns. If the
2579 second operand is a NOT, put it first so we will try to split the
2580 other operand first. */
2581 if (GET_CODE (XEXP (x, 1)) == NOT)
2583 rtx tem = XEXP (x, 0);
2584 SUBST (XEXP (x, 0), XEXP (x, 1));
2585 SUBST (XEXP (x, 1), tem);
2590 /* Otherwise, select our actions depending on our rtx class. */
2591 switch (GET_RTX_CLASS (code))
2593 case 'b': /* This is ZERO_EXTRACT and SIGN_EXTRACT. */
2595 split = find_split_point (&XEXP (x, 2), insn);
2598 /* ... fall through ... */
2602 split = find_split_point (&XEXP (x, 1), insn);
2605 /* ... fall through ... */
2607 /* Some machines have (and (shift ...) ...) insns. If X is not
2608 an AND, but XEXP (X, 0) is, use it as our split point. */
2609 if (GET_CODE (x) != AND && GET_CODE (XEXP (x, 0)) == AND)
2610 return &XEXP (x, 0);
2612 split = find_split_point (&XEXP (x, 0), insn);
2618 /* Otherwise, we don't have a split point. */
2622 /* Throughout X, replace FROM with TO, and return the result.
2623 The result is TO if X is FROM;
2624 otherwise the result is X, but its contents may have been modified.
2625 If they were modified, a record was made in undobuf so that
2626 undo_all will (among other things) return X to its original state.
2628 If the number of changes necessary is too much to record to undo,
2629 the excess changes are not made, so the result is invalid.
2630 The changes already made can still be undone.
2631 undobuf.num_undo is incremented for such changes, so by testing that
2632 the caller can tell whether the result is valid.
2634 `n_occurrences' is incremented each time FROM is replaced.
2636 IN_DEST is non-zero if we are processing the SET_DEST of a SET.
2638 UNIQUE_COPY is non-zero if each substitution must be unique. We do this
2639 by copying if `n_occurrences' is non-zero. */
2642 subst (x, from, to, in_dest, unique_copy)
2643 register rtx x, from, to;
2648 register int len, i;
2649 register enum rtx_code code = GET_CODE (x), orig_code = code;
2651 enum machine_mode mode = GET_MODE (x);
2652 enum machine_mode op0_mode = VOIDmode;
2657 /* FAKE_EXTEND_SAFE_P (MODE, FROM) is 1 if (subreg:MODE FROM 0) is a safe
2658 replacement for (zero_extend:MODE FROM) or (sign_extend:MODE FROM).
2659 If it is 0, that cannot be done. We can now do this for any MEM
2660 because (SUBREG (MEM...)) is guaranteed to cause the MEM to be reloaded.
2661 If not for that, MEM's would very rarely be safe. */
2663 /* Reject MODEs bigger than a word, because we might not be able
2664 to reference a two-register group starting with an arbitrary register
2665 (and currently gen_lowpart might crash for a SUBREG). */
2667 #define FAKE_EXTEND_SAFE_P(MODE, FROM) \
2668 (GET_MODE_SIZE (MODE) <= UNITS_PER_WORD)
2670 /* Two expressions are equal if they are identical copies of a shared
2671 RTX or if they are both registers with the same register number
2674 #define COMBINE_RTX_EQUAL_P(X,Y) \
2676 || (GET_CODE (X) == REG && GET_CODE (Y) == REG \
2677 && REGNO (X) == REGNO (Y) && GET_MODE (X) == GET_MODE (Y)))
2679 if (! in_dest && COMBINE_RTX_EQUAL_P (x, from))
2682 return (unique_copy && n_occurrences > 1 ? copy_rtx (to) : to);
2685 /* If X and FROM are the same register but different modes, they will
2686 not have been seen as equal above. However, flow.c will make a
2687 LOG_LINKS entry for that case. If we do nothing, we will try to
2688 rerecognize our original insn and, when it succeeds, we will
2689 delete the feeding insn, which is incorrect.
2691 So force this insn not to match in this (rare) case. */
2692 if (! in_dest && code == REG && GET_CODE (from) == REG
2693 && REGNO (x) == REGNO (from))
2694 return gen_rtx (CLOBBER, GET_MODE (x), const0_rtx);
2696 /* If this is an object, we are done unless it is a MEM or LO_SUM, both
2697 of which may contain things that can be combined. */
2698 if (code != MEM && code != LO_SUM && GET_RTX_CLASS (code) == 'o')
2701 /* It is possible to have a subexpression appear twice in the insn.
2702 Suppose that FROM is a register that appears within TO.
2703 Then, after that subexpression has been scanned once by `subst',
2704 the second time it is scanned, TO may be found. If we were
2705 to scan TO here, we would find FROM within it and create a
2706 self-referent rtl structure which is completely wrong. */
2707 if (COMBINE_RTX_EQUAL_P (x, to))
2710 len = GET_RTX_LENGTH (code);
2711 fmt = GET_RTX_FORMAT (code);
2713 /* We don't need to process a SET_DEST that is a register, CC0, or PC, so
2714 set up to skip this common case. All other cases where we want to
2715 suppress replacing something inside a SET_SRC are handled via the
2718 && (GET_CODE (SET_DEST (x)) == REG
2719 || GET_CODE (SET_DEST (x)) == CC0
2720 || GET_CODE (SET_DEST (x)) == PC))
2723 /* Get the mode of operand 0 in case X is now a SIGN_EXTEND of a constant. */
2725 op0_mode = GET_MODE (XEXP (x, 0));
2727 for (i = 0; i < len; i++)
2732 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2735 if (COMBINE_RTX_EQUAL_P (XVECEXP (x, i, j), from))
2737 new = (unique_copy && n_occurrences ? copy_rtx (to) : to);
2742 new = subst (XVECEXP (x, i, j), from, to, 0, unique_copy);
2744 /* If this substitution failed, this whole thing fails. */
2745 if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx)
2749 SUBST (XVECEXP (x, i, j), new);
2752 else if (fmt[i] == 'e')
2756 if (COMBINE_RTX_EQUAL_P (XEXP (x, i), from))
2758 new = (unique_copy && n_occurrences ? copy_rtx (to) : to);
2762 /* If we are in a SET_DEST, suppress most cases unless we
2763 have gone inside a MEM, in which case we want to
2764 simplify the address. We assume here that things that
2765 are actually part of the destination have their inner
2766 parts in the first expression. This is true for SUBREG,
2767 STRICT_LOW_PART, and ZERO_EXTRACT, which are the only
2768 things aside from REG and MEM that should appear in a
2770 new = subst (XEXP (x, i), from, to,
2772 && (code == SUBREG || code == STRICT_LOW_PART
2773 || code == ZERO_EXTRACT))
2775 && i == 0), unique_copy);
2777 /* If we found that we will have to reject this combination,
2778 indicate that by returning the CLOBBER ourselves, rather than
2779 an expression containing it. This will speed things up as
2780 well as prevent accidents where two CLOBBERs are considered
2781 to be equal, thus producing an incorrect simplification. */
2783 if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx)
2786 SUBST (XEXP (x, i), new);
2790 /* We come back to here if we have replaced the expression with one of
2791 a different code and it is likely that further simplification will be
2796 /* If we have restarted more than 4 times, we are probably looping, so
2798 if (++n_restarts > 4)
2801 /* If we are restarting at all, it means that we no longer know the
2802 original mode of operand 0 (since we have probably changed the
2806 op0_mode = VOIDmode;
2808 code = GET_CODE (x);
2810 /* If this is a commutative operation, put a constant last and a complex
2811 expression first. We don't need to do this for comparisons here. */
2812 if (GET_RTX_CLASS (code) == 'c'
2813 && ((CONSTANT_P (XEXP (x, 0)) && GET_CODE (XEXP (x, 1)) != CONST_INT)
2814 || (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'o'
2815 && GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) != 'o')
2816 || (GET_CODE (XEXP (x, 0)) == SUBREG
2817 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0)))) == 'o'
2818 && GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) != 'o')))
2821 SUBST (XEXP (x, 0), XEXP (x, 1));
2822 SUBST (XEXP (x, 1), temp);
2825 /* If this is a PLUS, MINUS, or MULT, and the first operand is the
2826 sign extension of a PLUS with a constant, reverse the order of the sign
2827 extension and the addition. Note that this not the same as the original
2828 code, but overflow is undefined for signed values. Also note that the
2829 PLUS will have been partially moved "inside" the sign-extension, so that
2830 the first operand of X will really look like:
2831 (ashiftrt (plus (ashift A C4) C5) C4).
2833 (plus (ashiftrt (ashift A C4) C2) C4)
2834 and replace the first operand of X with that expression. Later parts
2835 of this function may simplify the expression further.
2837 For example, if we start with (mult (sign_extend (plus A C1)) C2),
2838 we swap the SIGN_EXTEND and PLUS. Later code will apply the
2839 distributive law to produce (plus (mult (sign_extend X) C1) C3).
2841 We do this to simplify address expressions. */
2843 if ((code == PLUS || code == MINUS || code == MULT)
2844 && GET_CODE (XEXP (x, 0)) == ASHIFTRT
2845 && GET_CODE (XEXP (XEXP (x, 0), 0)) == PLUS
2846 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == ASHIFT
2847 && GET_CODE (XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 1)) == CONST_INT
2848 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2849 && XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 1) == XEXP (XEXP (x, 0), 1)
2850 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT
2851 && (temp = simplify_binary_operation (ASHIFTRT, mode,
2852 XEXP (XEXP (XEXP (x, 0), 0), 1),
2853 XEXP (XEXP (x, 0), 1))) != 0)
2856 = simplify_shift_const (NULL_RTX, ASHIFT, mode,
2857 XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 0),
2858 INTVAL (XEXP (XEXP (x, 0), 1)));
2860 new = simplify_shift_const (NULL_RTX, ASHIFTRT, mode, new,
2861 INTVAL (XEXP (XEXP (x, 0), 1)));
2863 SUBST (XEXP (x, 0), gen_binary (PLUS, mode, new, temp));
2866 /* If this is a simple operation applied to an IF_THEN_ELSE, try
2867 applying it to the arms of the IF_THEN_ELSE. This often simplifies
2868 things. Don't deal with operations that change modes here. */
2870 if ((GET_RTX_CLASS (code) == '2' || GET_RTX_CLASS (code) == 'c')
2871 && GET_CODE (XEXP (x, 0)) == IF_THEN_ELSE)
2873 /* Don't do this by using SUBST inside X since we might be messing
2874 up a shared expression. */
2875 rtx cond = XEXP (XEXP (x, 0), 0);
2876 rtx t_arm = subst (gen_binary (code, mode, XEXP (XEXP (x, 0), 1),
2878 pc_rtx, pc_rtx, 0, 0);
2879 rtx f_arm = subst (gen_binary (code, mode, XEXP (XEXP (x, 0), 2),
2881 pc_rtx, pc_rtx, 0, 0);
2884 x = gen_rtx (IF_THEN_ELSE, mode, cond, t_arm, f_arm);
2888 else if (GET_RTX_CLASS (code) == '1'
2889 && GET_CODE (XEXP (x, 0)) == IF_THEN_ELSE
2890 && GET_MODE (XEXP (x, 0)) == mode)
2892 rtx cond = XEXP (XEXP (x, 0), 0);
2893 rtx t_arm = subst (gen_unary (code, mode, XEXP (XEXP (x, 0), 1)),
2894 pc_rtx, pc_rtx, 0, 0);
2895 rtx f_arm = subst (gen_unary (code, mode, XEXP (XEXP (x, 0), 2)),
2896 pc_rtx, pc_rtx, 0, 0);
2898 x = gen_rtx_combine (IF_THEN_ELSE, mode, cond, t_arm, f_arm);
2902 /* Try to fold this expression in case we have constants that weren't
2905 switch (GET_RTX_CLASS (code))
2908 temp = simplify_unary_operation (code, mode, XEXP (x, 0), op0_mode);
2911 temp = simplify_relational_operation (code, op0_mode,
2912 XEXP (x, 0), XEXP (x, 1));
2913 #ifdef FLOAT_STORE_FLAG_VALUE
2914 if (temp != 0 && GET_MODE_CLASS (GET_MODE (x)) == MODE_FLOAT)
2915 temp = ((temp == const0_rtx) ? CONST0_RTX (GET_MODE (x))
2916 : immed_real_const_1 (FLOAT_STORE_FLAG_VALUE, GET_MODE (x)));
2921 temp = simplify_binary_operation (code, mode, XEXP (x, 0), XEXP (x, 1));
2925 temp = simplify_ternary_operation (code, mode, op0_mode, XEXP (x, 0),
2926 XEXP (x, 1), XEXP (x, 2));
2931 x = temp, code = GET_CODE (temp);
2933 /* First see if we can apply the inverse distributive law. */
2934 if (code == PLUS || code == MINUS
2935 || code == AND || code == IOR || code == XOR)
2937 x = apply_distributive_law (x);
2938 code = GET_CODE (x);
2941 /* If CODE is an associative operation not otherwise handled, see if we
2942 can associate some operands. This can win if they are constants or
2943 if they are logically related (i.e. (a & b) & a. */
2944 if ((code == PLUS || code == MINUS
2945 || code == MULT || code == AND || code == IOR || code == XOR
2946 || code == DIV || code == UDIV
2947 || code == SMAX || code == SMIN || code == UMAX || code == UMIN)
2948 && INTEGRAL_MODE_P (mode))
2950 if (GET_CODE (XEXP (x, 0)) == code)
2952 rtx other = XEXP (XEXP (x, 0), 0);
2953 rtx inner_op0 = XEXP (XEXP (x, 0), 1);
2954 rtx inner_op1 = XEXP (x, 1);
2957 /* Make sure we pass the constant operand if any as the second
2958 one if this is a commutative operation. */
2959 if (CONSTANT_P (inner_op0) && GET_RTX_CLASS (code) == 'c')
2961 rtx tem = inner_op0;
2962 inner_op0 = inner_op1;
2965 inner = simplify_binary_operation (code == MINUS ? PLUS
2966 : code == DIV ? MULT
2967 : code == UDIV ? MULT
2969 mode, inner_op0, inner_op1);
2971 /* For commutative operations, try the other pair if that one
2973 if (inner == 0 && GET_RTX_CLASS (code) == 'c')
2975 other = XEXP (XEXP (x, 0), 1);
2976 inner = simplify_binary_operation (code, mode,
2977 XEXP (XEXP (x, 0), 0),
2983 x = gen_binary (code, mode, other, inner);
2990 /* A little bit of algebraic simplification here. */
2994 /* Ensure that our address has any ASHIFTs converted to MULT in case
2995 address-recognizing predicates are called later. */
2996 temp = make_compound_operation (XEXP (x, 0), MEM);
2997 SUBST (XEXP (x, 0), temp);
3001 /* (subreg:A (mem:B X) N) becomes a modified MEM unless the SUBREG
3002 is paradoxical. If we can't do that safely, then it becomes
3003 something nonsensical so that this combination won't take place. */
3005 if (GET_CODE (SUBREG_REG (x)) == MEM
3006 && (GET_MODE_SIZE (mode)
3007 <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
3009 rtx inner = SUBREG_REG (x);
3010 int endian_offset = 0;
3011 /* Don't change the mode of the MEM
3012 if that would change the meaning of the address. */
3013 if (MEM_VOLATILE_P (SUBREG_REG (x))
3014 || mode_dependent_address_p (XEXP (inner, 0)))
3015 return gen_rtx (CLOBBER, mode, const0_rtx);
3017 #if BYTES_BIG_ENDIAN
3018 if (GET_MODE_SIZE (mode) < UNITS_PER_WORD)
3019 endian_offset += UNITS_PER_WORD - GET_MODE_SIZE (mode);
3020 if (GET_MODE_SIZE (GET_MODE (inner)) < UNITS_PER_WORD)
3021 endian_offset -= UNITS_PER_WORD - GET_MODE_SIZE (GET_MODE (inner));
3023 /* Note if the plus_constant doesn't make a valid address
3024 then this combination won't be accepted. */
3025 x = gen_rtx (MEM, mode,
3026 plus_constant (XEXP (inner, 0),
3027 (SUBREG_WORD (x) * UNITS_PER_WORD
3029 MEM_VOLATILE_P (x) = MEM_VOLATILE_P (inner);
3030 RTX_UNCHANGING_P (x) = RTX_UNCHANGING_P (inner);
3031 MEM_IN_STRUCT_P (x) = MEM_IN_STRUCT_P (inner);
3035 /* If we are in a SET_DEST, these other cases can't apply. */
3039 /* Changing mode twice with SUBREG => just change it once,
3040 or not at all if changing back to starting mode. */
3041 if (GET_CODE (SUBREG_REG (x)) == SUBREG)
3043 if (mode == GET_MODE (SUBREG_REG (SUBREG_REG (x)))
3044 && SUBREG_WORD (x) == 0 && SUBREG_WORD (SUBREG_REG (x)) == 0)
3045 return SUBREG_REG (SUBREG_REG (x));
3047 SUBST_INT (SUBREG_WORD (x),
3048 SUBREG_WORD (x) + SUBREG_WORD (SUBREG_REG (x)));
3049 SUBST (SUBREG_REG (x), SUBREG_REG (SUBREG_REG (x)));
3052 /* SUBREG of a hard register => just change the register number
3053 and/or mode. If the hard register is not valid in that mode,
3054 suppress this combination. If the hard register is the stack,
3055 frame, or argument pointer, leave this as a SUBREG. */
3057 if (GET_CODE (SUBREG_REG (x)) == REG
3058 && REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
3059 && REGNO (SUBREG_REG (x)) != FRAME_POINTER_REGNUM
3060 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3061 && REGNO (SUBREG_REG (x)) != ARG_POINTER_REGNUM
3063 && REGNO (SUBREG_REG (x)) != STACK_POINTER_REGNUM)
3065 if (HARD_REGNO_MODE_OK (REGNO (SUBREG_REG (x)) + SUBREG_WORD (x),
3067 return gen_rtx (REG, mode,
3068 REGNO (SUBREG_REG (x)) + SUBREG_WORD (x));
3070 return gen_rtx (CLOBBER, mode, const0_rtx);
3073 /* For a constant, try to pick up the part we want. Handle a full
3074 word and low-order part. Only do this if we are narrowing
3075 the constant; if it is being widened, we have no idea what
3076 the extra bits will have been set to. */
3078 if (CONSTANT_P (SUBREG_REG (x)) && op0_mode != VOIDmode
3079 && GET_MODE_SIZE (mode) == UNITS_PER_WORD
3080 && GET_MODE_SIZE (op0_mode) < UNITS_PER_WORD
3081 && GET_MODE_CLASS (mode) == MODE_INT)
3083 temp = operand_subword (SUBREG_REG (x), SUBREG_WORD (x),
3089 /* If we want a subreg of a constant, at offset 0,
3090 take the low bits. On a little-endian machine, that's
3091 always valid. On a big-endian machine, it's valid
3092 only if the constant's mode fits in one word. */
3093 if (CONSTANT_P (SUBREG_REG (x)) && subreg_lowpart_p (x)
3094 && GET_MODE_SIZE (mode) < GET_MODE_SIZE (op0_mode)
3095 #if WORDS_BIG_ENDIAN
3096 && GET_MODE_BITSIZE (op0_mode) <= BITS_PER_WORD
3099 return gen_lowpart_for_combine (mode, SUBREG_REG (x));
3101 /* If we are narrowing the object, we need to see if we can simplify
3102 the expression for the object knowing that we only need the
3105 if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))
3106 && subreg_lowpart_p (x))
3107 return force_to_mode (SUBREG_REG (x), mode, GET_MODE_BITSIZE (mode),
3112 /* (not (plus X -1)) can become (neg X). */
3113 if (GET_CODE (XEXP (x, 0)) == PLUS
3114 && XEXP (XEXP (x, 0), 1) == constm1_rtx)
3116 x = gen_rtx_combine (NEG, mode, XEXP (XEXP (x, 0), 0));
3120 /* Similarly, (not (neg X)) is (plus X -1). */
3121 if (GET_CODE (XEXP (x, 0)) == NEG)
3123 x = gen_rtx_combine (PLUS, mode, XEXP (XEXP (x, 0), 0), constm1_rtx);
3127 /* (not (xor X C)) for C constant is (xor X D) with D = ~ C. */
3128 if (GET_CODE (XEXP (x, 0)) == XOR
3129 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
3130 && (temp = simplify_unary_operation (NOT, mode,
3131 XEXP (XEXP (x, 0), 1),
3134 SUBST (XEXP (XEXP (x, 0), 1), temp);
3138 /* (not (ashift 1 X)) is (rotate ~1 X). We used to do this for operands
3139 other than 1, but that is not valid. We could do a similar
3140 simplification for (not (lshiftrt C X)) where C is just the sign bit,
3141 but this doesn't seem common enough to bother with. */
3142 if (GET_CODE (XEXP (x, 0)) == ASHIFT
3143 && XEXP (XEXP (x, 0), 0) == const1_rtx)
3145 x = gen_rtx (ROTATE, mode, gen_unary (NOT, mode, const1_rtx),
3146 XEXP (XEXP (x, 0), 1));
3150 if (GET_CODE (XEXP (x, 0)) == SUBREG
3151 && subreg_lowpart_p (XEXP (x, 0))
3152 && (GET_MODE_SIZE (GET_MODE (XEXP (x, 0)))
3153 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (x, 0)))))
3154 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == ASHIFT
3155 && XEXP (SUBREG_REG (XEXP (x, 0)), 0) == const1_rtx)
3157 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (XEXP (x, 0)));
3159 x = gen_rtx (ROTATE, inner_mode,
3160 gen_unary (NOT, inner_mode, const1_rtx),
3161 XEXP (SUBREG_REG (XEXP (x, 0)), 1));
3162 x = gen_lowpart_for_combine (mode, x);
3166 #if STORE_FLAG_VALUE == -1
3167 /* (not (comparison foo bar)) can be done by reversing the comparison
3169 if (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
3170 && reversible_comparison_p (XEXP (x, 0)))
3171 return gen_rtx_combine (reverse_condition (GET_CODE (XEXP (x, 0))),
3172 mode, XEXP (XEXP (x, 0), 0),
3173 XEXP (XEXP (x, 0), 1));
3175 /* (ashiftrt foo C) where C is the number of bits in FOO minus 1
3176 is (lt foo (const_int 0)), so we can perform the above
3179 if (XEXP (x, 1) == const1_rtx
3180 && GET_CODE (XEXP (x, 0)) == ASHIFTRT
3181 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
3182 && INTVAL (XEXP (XEXP (x, 0), 1)) == GET_MODE_BITSIZE (mode) - 1)
3183 return gen_rtx_combine (GE, mode, XEXP (XEXP (x, 0), 0), const0_rtx);
3186 /* Apply De Morgan's laws to reduce number of patterns for machines
3187 with negating logical insns (and-not, nand, etc.). If result has
3188 only one NOT, put it first, since that is how the patterns are
3191 if (GET_CODE (XEXP (x, 0)) == IOR || GET_CODE (XEXP (x, 0)) == AND)
3193 rtx in1 = XEXP (XEXP (x, 0), 0), in2 = XEXP (XEXP (x, 0), 1);
3195 if (GET_CODE (in1) == NOT)
3196 in1 = XEXP (in1, 0);
3198 in1 = gen_rtx_combine (NOT, GET_MODE (in1), in1);
3200 if (GET_CODE (in2) == NOT)
3201 in2 = XEXP (in2, 0);
3202 else if (GET_CODE (in2) == CONST_INT
3203 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
3204 in2 = GEN_INT (GET_MODE_MASK (mode) & ~ INTVAL (in2));
3206 in2 = gen_rtx_combine (NOT, GET_MODE (in2), in2);
3208 if (GET_CODE (in2) == NOT)
3211 in2 = in1; in1 = tem;
3214 x = gen_rtx_combine (GET_CODE (XEXP (x, 0)) == IOR ? AND : IOR,
3221 /* (neg (plus X 1)) can become (not X). */
3222 if (GET_CODE (XEXP (x, 0)) == PLUS
3223 && XEXP (XEXP (x, 0), 1) == const1_rtx)
3225 x = gen_rtx_combine (NOT, mode, XEXP (XEXP (x, 0), 0));
3229 /* Similarly, (neg (not X)) is (plus X 1). */
3230 if (GET_CODE (XEXP (x, 0)) == NOT)
3232 x = gen_rtx_combine (PLUS, mode, XEXP (XEXP (x, 0), 0), const1_rtx);
3236 /* (neg (minus X Y)) can become (minus Y X). */
3237 if (GET_CODE (XEXP (x, 0)) == MINUS
3238 && (! FLOAT_MODE_P (mode)
3239 /* x-y != -(y-x) with IEEE floating point. */
3240 || TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT))
3242 x = gen_binary (MINUS, mode, XEXP (XEXP (x, 0), 1),
3243 XEXP (XEXP (x, 0), 0));
3247 /* (neg (xor A 1)) is (plus A -1) if A is known to be either 0 or 1. */
3248 if (GET_CODE (XEXP (x, 0)) == XOR && XEXP (XEXP (x, 0), 1) == const1_rtx
3249 && nonzero_bits (XEXP (XEXP (x, 0), 0), mode) == 1)
3251 x = gen_binary (PLUS, mode, XEXP (XEXP (x, 0), 0), constm1_rtx);
3255 /* NEG commutes with ASHIFT since it is multiplication. Only do this
3256 if we can then eliminate the NEG (e.g.,
3257 if the operand is a constant). */
3259 if (GET_CODE (XEXP (x, 0)) == ASHIFT)
3261 temp = simplify_unary_operation (NEG, mode,
3262 XEXP (XEXP (x, 0), 0), mode);
3265 SUBST (XEXP (XEXP (x, 0), 0), temp);
3270 temp = expand_compound_operation (XEXP (x, 0));
3272 /* For C equal to the width of MODE minus 1, (neg (ashiftrt X C)) can be
3273 replaced by (lshiftrt X C). This will convert
3274 (neg (sign_extract X 1 Y)) to (zero_extract X 1 Y). */
3276 if (GET_CODE (temp) == ASHIFTRT
3277 && GET_CODE (XEXP (temp, 1)) == CONST_INT
3278 && INTVAL (XEXP (temp, 1)) == GET_MODE_BITSIZE (mode) - 1)
3280 x = simplify_shift_const (temp, LSHIFTRT, mode, XEXP (temp, 0),
3281 INTVAL (XEXP (temp, 1)));
3285 /* If X has only a single bit that might be nonzero, say, bit I, convert
3286 (neg X) to (ashiftrt (ashift X C-I) C-I) where C is the bitsize of
3287 MODE minus 1. This will convert (neg (zero_extract X 1 Y)) to
3288 (sign_extract X 1 Y). But only do this if TEMP isn't a register
3289 or a SUBREG of one since we'd be making the expression more
3290 complex if it was just a register. */
3292 if (GET_CODE (temp) != REG
3293 && ! (GET_CODE (temp) == SUBREG
3294 && GET_CODE (SUBREG_REG (temp)) == REG)
3295 && (i = exact_log2 (nonzero_bits (temp, mode))) >= 0)
3297 rtx temp1 = simplify_shift_const
3298 (NULL_RTX, ASHIFTRT, mode,
3299 simplify_shift_const (NULL_RTX, ASHIFT, mode, temp,
3300 GET_MODE_BITSIZE (mode) - 1 - i),
3301 GET_MODE_BITSIZE (mode) - 1 - i);
3303 /* If all we did was surround TEMP with the two shifts, we
3304 haven't improved anything, so don't use it. Otherwise,
3305 we are better off with TEMP1. */
3306 if (GET_CODE (temp1) != ASHIFTRT
3307 || GET_CODE (XEXP (temp1, 0)) != ASHIFT
3308 || XEXP (XEXP (temp1, 0), 0) != temp)
3316 case FLOAT_TRUNCATE:
3317 /* (float_truncate:SF (float_extend:DF foo:SF)) = foo:SF. */
3318 if (GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND
3319 && GET_MODE (XEXP (XEXP (x, 0), 0)) == mode)
3320 return XEXP (XEXP (x, 0), 0);
3325 /* Convert (compare FOO (const_int 0)) to FOO unless we aren't
3326 using cc0, in which case we want to leave it as a COMPARE
3327 so we can distinguish it from a register-register-copy. */
3328 if (XEXP (x, 1) == const0_rtx)
3331 /* In IEEE floating point, x-0 is not the same as x. */
3332 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3333 || ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0))))
3334 && XEXP (x, 1) == CONST0_RTX (GET_MODE (XEXP (x, 0))))
3340 /* (const (const X)) can become (const X). Do it this way rather than
3341 returning the inner CONST since CONST can be shared with a
3343 if (GET_CODE (XEXP (x, 0)) == CONST)
3344 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
3349 /* Convert (lo_sum (high FOO) FOO) to FOO. This is necessary so we
3350 can add in an offset. find_split_point will split this address up
3351 again if it doesn't match. */
3352 if (GET_CODE (XEXP (x, 0)) == HIGH
3353 && rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1)))
3359 /* If we have (plus (plus (A const) B)), associate it so that CONST is
3360 outermost. That's because that's the way indexed addresses are
3361 supposed to appear. This code used to check many more cases, but
3362 they are now checked elsewhere. */
3363 if (GET_CODE (XEXP (x, 0)) == PLUS
3364 && CONSTANT_ADDRESS_P (XEXP (XEXP (x, 0), 1)))
3365 return gen_binary (PLUS, mode,
3366 gen_binary (PLUS, mode, XEXP (XEXP (x, 0), 0),
3368 XEXP (XEXP (x, 0), 1));
3370 /* (plus (xor (and <foo> (const_int pow2 - 1)) <c>) <-c>)
3371 when c is (const_int (pow2 + 1) / 2) is a sign extension of a
3372 bit-field and can be replaced by either a sign_extend or a
3373 sign_extract. The `and' may be a zero_extend. */
3374 if (GET_CODE (XEXP (x, 0)) == XOR
3375 && GET_CODE (XEXP (x, 1)) == CONST_INT
3376 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
3377 && INTVAL (XEXP (x, 1)) == - INTVAL (XEXP (XEXP (x, 0), 1))
3378 && (i = exact_log2 (INTVAL (XEXP (XEXP (x, 0), 1)))) >= 0
3379 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
3380 && ((GET_CODE (XEXP (XEXP (x, 0), 0)) == AND
3381 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT
3382 && (INTVAL (XEXP (XEXP (XEXP (x, 0), 0), 1))
3383 == ((HOST_WIDE_INT) 1 << (i + 1)) - 1))
3384 || (GET_CODE (XEXP (XEXP (x, 0), 0)) == ZERO_EXTEND
3385 && (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (XEXP (x, 0), 0), 0)))
3388 x = simplify_shift_const
3389 (NULL_RTX, ASHIFTRT, mode,
3390 simplify_shift_const (NULL_RTX, ASHIFT, mode,
3391 XEXP (XEXP (XEXP (x, 0), 0), 0),
3392 GET_MODE_BITSIZE (mode) - (i + 1)),
3393 GET_MODE_BITSIZE (mode) - (i + 1));
3397 /* (plus (comparison A B) C) can become (neg (rev-comp A B)) if
3398 C is 1 and STORE_FLAG_VALUE is -1 or if C is -1 and STORE_FLAG_VALUE
3399 is 1. This produces better code than the alternative immediately
3401 if (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
3402 && reversible_comparison_p (XEXP (x, 0))
3403 && ((STORE_FLAG_VALUE == -1 && XEXP (x, 1) == const1_rtx)
3404 || (STORE_FLAG_VALUE == 1 && XEXP (x, 1) == constm1_rtx)))
3406 x = gen_binary (reverse_condition (GET_CODE (XEXP (x, 0))),
3407 mode, XEXP (XEXP (x, 0), 0), XEXP (XEXP (x, 0), 1));
3408 x = gen_unary (NEG, mode, x);
3412 /* If only the low-order bit of X is possibly nonzero, (plus x -1)
3413 can become (ashiftrt (ashift (xor x 1) C) C) where C is
3414 the bitsize of the mode - 1. This allows simplification of
3415 "a = (b & 8) == 0;" */
3416 if (XEXP (x, 1) == constm1_rtx
3417 && GET_CODE (XEXP (x, 0)) != REG
3418 && ! (GET_CODE (XEXP (x,0)) == SUBREG
3419 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == REG)
3420 && nonzero_bits (XEXP (x, 0), mode) == 1)
3422 x = simplify_shift_const
3423 (NULL_RTX, ASHIFTRT, mode,
3424 simplify_shift_const (NULL_RTX, ASHIFT, mode,
3425 gen_rtx_combine (XOR, mode,
3426 XEXP (x, 0), const1_rtx),
3427 GET_MODE_BITSIZE (mode) - 1),
3428 GET_MODE_BITSIZE (mode) - 1);
3432 /* If we are adding two things that have no bits in common, convert
3433 the addition into an IOR. This will often be further simplified,
3434 for example in cases like ((a & 1) + (a & 2)), which can
3437 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
3438 && (nonzero_bits (XEXP (x, 0), mode)
3439 & nonzero_bits (XEXP (x, 1), mode)) == 0)
3441 x = gen_binary (IOR, mode, XEXP (x, 0), XEXP (x, 1));
3447 /* (minus <foo> (and <foo> (const_int -pow2))) becomes
3448 (and <foo> (const_int pow2-1)) */
3449 if (GET_CODE (XEXP (x, 1)) == AND
3450 && GET_CODE (XEXP (XEXP (x, 1), 1)) == CONST_INT
3451 && exact_log2 (- INTVAL (XEXP (XEXP (x, 1), 1))) >= 0
3452 && rtx_equal_p (XEXP (XEXP (x, 1), 0), XEXP (x, 0)))
3454 x = simplify_and_const_int (NULL_RTX, mode, XEXP (x, 0),
3455 - INTVAL (XEXP (XEXP (x, 1), 1)) - 1);
3461 /* If we have (mult (plus A B) C), apply the distributive law and then
3462 the inverse distributive law to see if things simplify. This
3463 occurs mostly in addresses, often when unrolling loops. */
3465 if (GET_CODE (XEXP (x, 0)) == PLUS)
3467 x = apply_distributive_law
3468 (gen_binary (PLUS, mode,
3469 gen_binary (MULT, mode,
3470 XEXP (XEXP (x, 0), 0), XEXP (x, 1)),
3471 gen_binary (MULT, mode,
3472 XEXP (XEXP (x, 0), 1), XEXP (x, 1))));
3474 if (GET_CODE (x) != MULT)
3478 /* If this is multiplication by a power of two and its first operand is
3479 a shift, treat the multiply as a shift to allow the shifts to
3480 possibly combine. */
3481 if (GET_CODE (XEXP (x, 1)) == CONST_INT
3482 && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0
3483 && (GET_CODE (XEXP (x, 0)) == ASHIFT
3484 || GET_CODE (XEXP (x, 0)) == LSHIFTRT
3485 || GET_CODE (XEXP (x, 0)) == ASHIFTRT
3486 || GET_CODE (XEXP (x, 0)) == ROTATE
3487 || GET_CODE (XEXP (x, 0)) == ROTATERT))
3489 x = simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (x, 0), i);
3493 /* Convert (mult (ashift (const_int 1) A) B) to (ashift B A). */
3494 if (GET_CODE (XEXP (x, 0)) == ASHIFT
3495 && XEXP (XEXP (x, 0), 0) == const1_rtx)
3496 return gen_rtx_combine (ASHIFT, mode, XEXP (x, 1),
3497 XEXP (XEXP (x, 0), 1));
3501 /* If this is a divide by a power of two, treat it as a shift if
3502 its first operand is a shift. */
3503 if (GET_CODE (XEXP (x, 1)) == CONST_INT
3504 && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0
3505 && (GET_CODE (XEXP (x, 0)) == ASHIFT
3506 || GET_CODE (XEXP (x, 0)) == LSHIFTRT
3507 || GET_CODE (XEXP (x, 0)) == ASHIFTRT
3508 || GET_CODE (XEXP (x, 0)) == ROTATE
3509 || GET_CODE (XEXP (x, 0)) == ROTATERT))
3511 x = simplify_shift_const (NULL_RTX, LSHIFTRT, mode, XEXP (x, 0), i);
3517 case GT: case GTU: case GE: case GEU:
3518 case LT: case LTU: case LE: case LEU:
3519 /* If the first operand is a condition code, we can't do anything
3521 if (GET_CODE (XEXP (x, 0)) == COMPARE
3522 || (GET_MODE_CLASS (GET_MODE (XEXP (x, 0))) != MODE_CC
3524 && XEXP (x, 0) != cc0_rtx
3528 rtx op0 = XEXP (x, 0);
3529 rtx op1 = XEXP (x, 1);
3530 enum rtx_code new_code;
3532 if (GET_CODE (op0) == COMPARE)
3533 op1 = XEXP (op0, 1), op0 = XEXP (op0, 0);
3535 /* Simplify our comparison, if possible. */
3536 new_code = simplify_comparison (code, &op0, &op1);
3538 #if STORE_FLAG_VALUE == 1
3539 /* If STORE_FLAG_VALUE is 1, we can convert (ne x 0) to simply X
3540 if only the low-order bit is possibly nonzero in X (such as when
3541 X is a ZERO_EXTRACT of one bit. Similarly, we can convert
3542 EQ to (xor X 1). Remove any ZERO_EXTRACT we made when thinking
3543 this was a comparison. It may now be simpler to use, e.g., an
3544 AND. If a ZERO_EXTRACT is indeed appropriate, it will
3545 be placed back by the call to make_compound_operation in the
3547 if (new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
3548 && op1 == const0_rtx
3549 && nonzero_bits (op0, GET_MODE (op0)) == 1)
3550 return gen_lowpart_for_combine (mode,
3551 expand_compound_operation (op0));
3552 else if (new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT
3553 && op1 == const0_rtx
3554 && nonzero_bits (op0, GET_MODE (op0)) == 1)
3556 op0 = expand_compound_operation (op0);
3558 x = gen_rtx_combine (XOR, mode,
3559 gen_lowpart_for_combine (mode, op0),
3565 #if STORE_FLAG_VALUE == -1
3566 /* If STORE_FLAG_VALUE is -1, we can convert (ne x 0)
3567 to (neg x) if only the low-order bit of X can be nonzero.
3568 This converts (ne (zero_extract X 1 Y) 0) to
3569 (sign_extract X 1 Y). */
3570 if (new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
3571 && op1 == const0_rtx
3572 && nonzero_bits (op0, GET_MODE (op0)) == 1)
3574 op0 = expand_compound_operation (op0);
3575 x = gen_rtx_combine (NEG, mode,
3576 gen_lowpart_for_combine (mode, op0));
3581 /* If STORE_FLAG_VALUE says to just test the sign bit and X has just
3582 one bit that might be nonzero, we can convert (ne x 0) to
3583 (ashift x c) where C puts the bit in the sign bit. Remove any
3584 AND with STORE_FLAG_VALUE when we are done, since we are only
3585 going to test the sign bit. */
3586 if (new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
3587 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
3588 && (STORE_FLAG_VALUE
3589 == (HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1))
3590 && op1 == const0_rtx
3591 && mode == GET_MODE (op0)
3592 && (i = exact_log2 (nonzero_bits (op0, GET_MODE (op0)))) >= 0)
3594 x = simplify_shift_const (NULL_RTX, ASHIFT, mode,
3595 expand_compound_operation (op0),
3596 GET_MODE_BITSIZE (mode) - 1 - i);
3597 if (GET_CODE (x) == AND && XEXP (x, 1) == const_true_rtx)
3603 /* If the code changed, return a whole new comparison. */
3604 if (new_code != code)
3605 return gen_rtx_combine (new_code, mode, op0, op1);
3607 /* Otherwise, keep this operation, but maybe change its operands.
3608 This also converts (ne (compare FOO BAR) 0) to (ne FOO BAR). */
3609 SUBST (XEXP (x, 0), op0);
3610 SUBST (XEXP (x, 1), op1);
3615 /* Sometimes we can simplify the arm of an IF_THEN_ELSE if a register
3616 used in it is being compared against certain values. Get the
3617 true and false comparisons and see if that says anything about the
3618 value of each arm. */
3620 if (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
3621 && reversible_comparison_p (XEXP (x, 0))
3622 && GET_CODE (XEXP (XEXP (x, 0), 0)) == REG)
3625 rtx from = XEXP (XEXP (x, 0), 0);
3626 enum rtx_code true_code = GET_CODE (XEXP (x, 0));
3627 enum rtx_code false_code = reverse_condition (true_code);
3628 rtx true_val = XEXP (XEXP (x, 0), 1);
3629 rtx false_val = true_val;
3630 rtx true_arm = XEXP (x, 1);
3631 rtx false_arm = XEXP (x, 2);
3634 /* If FALSE_CODE is EQ, swap the codes and arms. */
3636 if (false_code == EQ)
3638 swapped = 1, true_code = EQ, false_code = NE;
3639 true_arm = XEXP (x, 2), false_arm = XEXP (x, 1);
3642 /* If we are comparing against zero and the expression being tested
3643 has only a single bit that might be nonzero, that is its value
3644 when it is not equal to zero. Similarly if it is known to be
3647 if (true_code == EQ && true_val == const0_rtx
3648 && exact_log2 (nzb = nonzero_bits (from, GET_MODE (from))) >= 0)
3649 false_code = EQ, false_val = GEN_INT (nzb);
3650 else if (true_code == EQ && true_val == const0_rtx
3651 && (num_sign_bit_copies (from, GET_MODE (from))
3652 == GET_MODE_BITSIZE (GET_MODE (from))))
3653 false_code = EQ, false_val = constm1_rtx;
3655 /* Now simplify an arm if we know the value of the register
3656 in the branch and it is used in the arm. Be carefull due to
3657 the potential of locally-shared RTL. */
3659 if (reg_mentioned_p (from, true_arm))
3660 true_arm = subst (known_cond (copy_rtx (true_arm), true_code,
3662 pc_rtx, pc_rtx, 0, 0);
3663 if (reg_mentioned_p (from, false_arm))
3664 false_arm = subst (known_cond (copy_rtx (false_arm), false_code,
3666 pc_rtx, pc_rtx, 0, 0);
3668 SUBST (XEXP (x, 1), swapped ? false_arm : true_arm);
3669 SUBST (XEXP (x, 2), swapped ? true_arm : false_arm);
3672 /* If we have (if_then_else FOO (pc) (label_ref BAR)) and FOO can be
3673 reversed, do so to avoid needing two sets of patterns for
3674 subtract-and-branch insns. Similarly if we have a constant in that
3675 position or if the third operand is the same as the first operand
3676 of the comparison. */
3678 if (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
3679 && reversible_comparison_p (XEXP (x, 0))
3680 && (XEXP (x, 1) == pc_rtx || GET_CODE (XEXP (x, 1)) == CONST_INT
3681 || rtx_equal_p (XEXP (x, 2), XEXP (XEXP (x, 0), 0))))
3684 gen_binary (reverse_condition (GET_CODE (XEXP (x, 0))),
3685 GET_MODE (XEXP (x, 0)),
3686 XEXP (XEXP (x, 0), 0), XEXP (XEXP (x, 0), 1)));
3689 SUBST (XEXP (x, 1), XEXP (x, 2));
3690 SUBST (XEXP (x, 2), temp);
3693 /* If the two arms are identical, we don't need the comparison. */
3695 if (rtx_equal_p (XEXP (x, 1), XEXP (x, 2))
3696 && ! side_effects_p (XEXP (x, 0)))
3699 /* Look for cases where we have (abs x) or (neg (abs X)). */
3701 if (GET_MODE_CLASS (mode) == MODE_INT
3702 && GET_CODE (XEXP (x, 2)) == NEG
3703 && rtx_equal_p (XEXP (x, 1), XEXP (XEXP (x, 2), 0))
3704 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
3705 && rtx_equal_p (XEXP (x, 1), XEXP (XEXP (x, 0), 0))
3706 && ! side_effects_p (XEXP (x, 1)))
3707 switch (GET_CODE (XEXP (x, 0)))
3711 x = gen_unary (ABS, mode, XEXP (x, 1));
3715 x = gen_unary (NEG, mode, gen_unary (ABS, mode, XEXP (x, 1)));
3719 /* Look for MIN or MAX. */
3721 if (! FLOAT_MODE_P (mode)
3722 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
3723 && rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1))
3724 && rtx_equal_p (XEXP (XEXP (x, 0), 1), XEXP (x, 2))
3725 && ! side_effects_p (XEXP (x, 0)))
3726 switch (GET_CODE (XEXP (x, 0)))
3730 x = gen_binary (SMAX, mode, XEXP (x, 1), XEXP (x, 2));
3734 x = gen_binary (SMIN, mode, XEXP (x, 1), XEXP (x, 2));
3738 x = gen_binary (UMAX, mode, XEXP (x, 1), XEXP (x, 2));
3742 x = gen_binary (UMIN, mode, XEXP (x, 1), XEXP (x, 2));
3746 /* If we have something like (if_then_else (ne A 0) (OP X C) X),
3747 A is known to be either 0 or 1, and OP is an identity when its
3748 second operand is zero, this can be done as (OP X (mult A C)).
3749 Similarly if A is known to be 0 or -1 and also similarly if we have
3750 a ZERO_EXTEND or SIGN_EXTEND as long as X is already extended (so
3751 we don't destroy it). */
3753 if (mode != VOIDmode
3754 && (GET_CODE (XEXP (x, 0)) == EQ || GET_CODE (XEXP (x, 0)) == NE)
3755 && XEXP (XEXP (x, 0), 1) == const0_rtx
3756 && (nonzero_bits (XEXP (XEXP (x, 0), 0), mode) == 1
3757 || (num_sign_bit_copies (XEXP (XEXP (x, 0), 0), mode)
3758 == GET_MODE_BITSIZE (mode))))
3760 rtx nz = make_compound_operation (GET_CODE (XEXP (x, 0)) == NE
3761 ? XEXP (x, 1) : XEXP (x, 2));
3762 rtx z = GET_CODE (XEXP (x, 0)) == NE ? XEXP (x, 2) : XEXP (x, 1);
3763 rtx dir = (nonzero_bits (XEXP (XEXP (x, 0), 0), mode) == 1
3764 ? const1_rtx : constm1_rtx);
3766 enum machine_mode m = mode;
3767 enum rtx_code op, extend_op = 0;
3769 if ((GET_CODE (nz) == PLUS || GET_CODE (nz) == MINUS
3770 || GET_CODE (nz) == IOR || GET_CODE (nz) == XOR
3771 || GET_CODE (nz) == ASHIFT
3772 || GET_CODE (nz) == LSHIFTRT || GET_CODE (nz) == ASHIFTRT)
3773 && rtx_equal_p (XEXP (nz, 0), z))
3774 c = XEXP (nz, 1), op = GET_CODE (nz);
3775 else if (GET_CODE (nz) == SIGN_EXTEND
3776 && (GET_CODE (XEXP (nz, 0)) == PLUS
3777 || GET_CODE (XEXP (nz, 0)) == MINUS
3778 || GET_CODE (XEXP (nz, 0)) == IOR
3779 || GET_CODE (XEXP (nz, 0)) == XOR
3780 || GET_CODE (XEXP (nz, 0)) == ASHIFT
3781 || GET_CODE (XEXP (nz, 0)) == LSHIFTRT
3782 || GET_CODE (XEXP (nz, 0)) == ASHIFTRT)
3783 && GET_CODE (XEXP (XEXP (nz, 0), 0)) == SUBREG
3784 && subreg_lowpart_p (XEXP (XEXP (nz, 0), 0))
3785 && rtx_equal_p (SUBREG_REG (XEXP (XEXP (nz, 0), 0)), z)
3786 && (num_sign_bit_copies (z, GET_MODE (z))
3787 >= (GET_MODE_BITSIZE (mode)
3788 - GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (nz, 0), 0))))))
3790 c = XEXP (XEXP (nz, 0), 1);
3791 op = GET_CODE (XEXP (nz, 0));
3792 extend_op = SIGN_EXTEND;
3793 m = GET_MODE (XEXP (nz, 0));
3795 else if (GET_CODE (nz) == ZERO_EXTEND
3796 && (GET_CODE (XEXP (nz, 0)) == PLUS
3797 || GET_CODE (XEXP (nz, 0)) == MINUS
3798 || GET_CODE (XEXP (nz, 0)) == IOR
3799 || GET_CODE (XEXP (nz, 0)) == XOR
3800 || GET_CODE (XEXP (nz, 0)) == ASHIFT
3801 || GET_CODE (XEXP (nz, 0)) == LSHIFTRT
3802 || GET_CODE (XEXP (nz, 0)) == ASHIFTRT)
3803 && GET_CODE (XEXP (XEXP (nz, 0), 0)) == SUBREG
3804 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
3805 && subreg_lowpart_p (XEXP (XEXP (nz, 0), 0))
3806 && rtx_equal_p (SUBREG_REG (XEXP (XEXP (nz, 0), 0)), z)
3807 && ((nonzero_bits (z, GET_MODE (z))
3808 & ~ GET_MODE_MASK (GET_MODE (XEXP (XEXP (nz, 0), 0))))
3811 c = XEXP (XEXP (nz, 0), 1);
3812 op = GET_CODE (XEXP (nz, 0));
3813 extend_op = ZERO_EXTEND;
3814 m = GET_MODE (XEXP (nz, 0));
3817 if (c && ! side_effects_p (c) && ! side_effects_p (z))
3820 = gen_binary (MULT, m,
3821 gen_lowpart_for_combine (m,
3822 XEXP (XEXP (x, 0), 0)),
3823 gen_binary (MULT, m, c, dir));
3825 temp = gen_binary (op, m, gen_lowpart_for_combine (m, z), temp);
3828 temp = gen_unary (extend_op, mode, temp);
3834 /* If we have (if_then_else (ne A 0) C1 0) and either A is known to
3835 be 0 or 1 and C1 is a single bit or A is known to be 0 or -1 and
3836 C1 is the negation of a single bit, we can convert this operation
3837 to a shift. We can actually do this in more general cases, but it
3838 doesn't seem worth it. */
3840 if (GET_CODE (XEXP (x, 0)) == NE && XEXP (XEXP (x, 0), 1) == const0_rtx
3841 && XEXP (x, 2) == const0_rtx && GET_CODE (XEXP (x, 1)) == CONST_INT
3842 && ((1 == nonzero_bits (XEXP (XEXP (x, 0), 0), mode)
3843 && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0)
3844 || ((num_sign_bit_copies (XEXP (XEXP (x, 0), 0), mode)
3845 == GET_MODE_BITSIZE (mode))
3846 && (i = exact_log2 (- INTVAL (XEXP (x, 1)))) >= 0)))
3848 simplify_shift_const (NULL_RTX, ASHIFT, mode,
3849 gen_lowpart_for_combine (mode,
3850 XEXP (XEXP (x, 0), 0)),
3858 /* If we are processing SET_DEST, we are done. */
3862 x = expand_compound_operation (x);
3863 if (GET_CODE (x) != code)
3868 /* (set (pc) (return)) gets written as (return). */
3869 if (GET_CODE (SET_DEST (x)) == PC && GET_CODE (SET_SRC (x)) == RETURN)
3872 /* Convert this into a field assignment operation, if possible. */
3873 x = make_field_assignment (x);
3875 /* If we are setting CC0 or if the source is a COMPARE, look for the
3876 use of the comparison result and try to simplify it unless we already
3877 have used undobuf.other_insn. */
3878 if ((GET_CODE (SET_SRC (x)) == COMPARE
3880 || SET_DEST (x) == cc0_rtx
3883 && (cc_use = find_single_use (SET_DEST (x), subst_insn,
3885 && (undobuf.other_insn == 0 || other_insn == undobuf.other_insn)
3886 && GET_RTX_CLASS (GET_CODE (*cc_use)) == '<'
3887 && XEXP (*cc_use, 0) == SET_DEST (x))
3889 enum rtx_code old_code = GET_CODE (*cc_use);
3890 enum rtx_code new_code;
3892 int other_changed = 0;
3893 enum machine_mode compare_mode = GET_MODE (SET_DEST (x));
3895 if (GET_CODE (SET_SRC (x)) == COMPARE)
3896 op0 = XEXP (SET_SRC (x), 0), op1 = XEXP (SET_SRC (x), 1);
3898 op0 = SET_SRC (x), op1 = const0_rtx;
3900 /* Simplify our comparison, if possible. */
3901 new_code = simplify_comparison (old_code, &op0, &op1);
3903 #ifdef EXTRA_CC_MODES
3904 /* If this machine has CC modes other than CCmode, check to see
3905 if we need to use a different CC mode here. */
3906 compare_mode = SELECT_CC_MODE (new_code, op0, op1);
3907 #endif /* EXTRA_CC_MODES */
3909 #if !defined (HAVE_cc0) && defined (EXTRA_CC_MODES)
3910 /* If the mode changed, we have to change SET_DEST, the mode
3911 in the compare, and the mode in the place SET_DEST is used.
3912 If SET_DEST is a hard register, just build new versions with
3913 the proper mode. If it is a pseudo, we lose unless it is only
3914 time we set the pseudo, in which case we can safely change
3916 if (compare_mode != GET_MODE (SET_DEST (x)))
3918 int regno = REGNO (SET_DEST (x));
3919 rtx new_dest = gen_rtx (REG, compare_mode, regno);
3921 if (regno < FIRST_PSEUDO_REGISTER
3922 || (reg_n_sets[regno] == 1
3923 && ! REG_USERVAR_P (SET_DEST (x))))
3925 if (regno >= FIRST_PSEUDO_REGISTER)
3926 SUBST (regno_reg_rtx[regno], new_dest);
3928 SUBST (SET_DEST (x), new_dest);
3929 SUBST (XEXP (*cc_use, 0), new_dest);
3935 /* If the code changed, we have to build a new comparison
3936 in undobuf.other_insn. */
3937 if (new_code != old_code)
3939 unsigned HOST_WIDE_INT mask;
3941 SUBST (*cc_use, gen_rtx_combine (new_code, GET_MODE (*cc_use),
3942 SET_DEST (x), const0_rtx));
3944 /* If the only change we made was to change an EQ into an
3945 NE or vice versa, OP0 has only one bit that might be nonzero,
3946 and OP1 is zero, check if changing the user of the condition
3947 code will produce a valid insn. If it won't, we can keep
3948 the original code in that insn by surrounding our operation
3951 if (((old_code == NE && new_code == EQ)
3952 || (old_code == EQ && new_code == NE))
3953 && ! other_changed && op1 == const0_rtx
3954 && (GET_MODE_BITSIZE (GET_MODE (op0))
3955 <= HOST_BITS_PER_WIDE_INT)
3956 && (exact_log2 (mask = nonzero_bits (op0, GET_MODE (op0)))
3959 rtx pat = PATTERN (other_insn), note = 0;
3961 if ((recog_for_combine (&pat, other_insn, ¬e) < 0
3962 && ! check_asm_operands (pat)))
3964 PUT_CODE (*cc_use, old_code);
3967 op0 = gen_binary (XOR, GET_MODE (op0), op0,
3976 undobuf.other_insn = other_insn;
3979 /* If we are now comparing against zero, change our source if
3980 needed. If we do not use cc0, we always have a COMPARE. */
3981 if (op1 == const0_rtx && SET_DEST (x) == cc0_rtx)
3982 SUBST (SET_SRC (x), op0);
3986 /* Otherwise, if we didn't previously have a COMPARE in the
3987 correct mode, we need one. */
3988 if (GET_CODE (SET_SRC (x)) != COMPARE
3989 || GET_MODE (SET_SRC (x)) != compare_mode)
3990 SUBST (SET_SRC (x), gen_rtx_combine (COMPARE, compare_mode,
3994 /* Otherwise, update the COMPARE if needed. */
3995 SUBST (XEXP (SET_SRC (x), 0), op0);
3996 SUBST (XEXP (SET_SRC (x), 1), op1);
4001 /* Get SET_SRC in a form where we have placed back any
4002 compound expressions. Then do the checks below. */
4003 temp = make_compound_operation (SET_SRC (x), SET);
4004 SUBST (SET_SRC (x), temp);
4007 /* If we have (set x (subreg:m1 (op:m2 ...) 0)) with OP being some
4008 operation, and X being a REG or (subreg (reg)), we may be able to
4009 convert this to (set (subreg:m2 x) (op)).
4011 We can always do this if M1 is narrower than M2 because that
4012 means that we only care about the low bits of the result.
4014 However, on most machines (those with neither BYTE_LOADS_ZERO_EXTEND
4015 nor BYTE_LOADS_SIGN_EXTEND defined), we cannot perform a
4016 narrower operation that requested since the high-order bits will
4017 be undefined. On machine where BYTE_LOADS_*_EXTEND is defined,
4018 however, this transformation is safe as long as M1 and M2 have
4019 the same number of words. */
4021 if (GET_CODE (SET_SRC (x)) == SUBREG
4022 && subreg_lowpart_p (SET_SRC (x))
4023 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (SET_SRC (x)))) != 'o'
4024 && (((GET_MODE_SIZE (GET_MODE (SET_SRC (x))) + (UNITS_PER_WORD - 1))
4026 == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_SRC (x))))
4027 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))
4028 #ifndef BYTE_LOADS_EXTEND
4029 && (GET_MODE_SIZE (GET_MODE (SET_SRC (x)))
4030 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_SRC (x)))))
4032 && (GET_CODE (SET_DEST (x)) == REG
4033 || (GET_CODE (SET_DEST (x)) == SUBREG
4034 && GET_CODE (SUBREG_REG (SET_DEST (x))) == REG)))
4036 SUBST (SET_DEST (x),
4037 gen_lowpart_for_combine (GET_MODE (SUBREG_REG (SET_SRC (x))),
4039 SUBST (SET_SRC (x), SUBREG_REG (SET_SRC (x)));
4042 #ifdef BYTE_LOADS_EXTEND
4043 /* If we have (set FOO (subreg:M (mem:N BAR) 0)) with
4044 M wider than N, this would require a paradoxical subreg.
4045 Replace the subreg with a zero_extend to avoid the reload that
4046 would otherwise be required. */
4048 if (GET_CODE (SET_SRC (x)) == SUBREG
4049 && subreg_lowpart_p (SET_SRC (x))
4050 && SUBREG_WORD (SET_SRC (x)) == 0
4051 && (GET_MODE_SIZE (GET_MODE (SET_SRC (x)))
4052 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_SRC (x)))))
4053 && GET_CODE (SUBREG_REG (SET_SRC (x))) == MEM)
4054 SUBST (SET_SRC (x), gen_rtx_combine (LOAD_EXTEND,
4055 GET_MODE (SET_SRC (x)),
4056 XEXP (SET_SRC (x), 0)));
4059 #ifndef HAVE_conditional_move
4061 /* If we don't have a conditional move, SET_SRC is an IF_THEN_ELSE,
4062 and we are comparing an item known to be 0 or -1 against 0, use a
4063 logical operation instead. Check for one of the arms being an IOR
4064 of the other arm with some value. We compute three terms to be
4065 IOR'ed together. In practice, at most two will be nonzero. Then
4068 if (GET_CODE (SET_DEST (x)) != PC
4069 && GET_CODE (SET_SRC (x)) == IF_THEN_ELSE
4070 && (GET_CODE (XEXP (SET_SRC (x), 0)) == EQ
4071 || GET_CODE (XEXP (SET_SRC (x), 0)) == NE)
4072 && XEXP (XEXP (SET_SRC (x), 0), 1) == const0_rtx
4073 && (num_sign_bit_copies (XEXP (XEXP (SET_SRC (x), 0), 0),
4074 GET_MODE (XEXP (XEXP (SET_SRC (x), 0), 0)))
4075 == GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (SET_SRC (x), 0), 0))))
4076 && ! side_effects_p (SET_SRC (x)))
4078 rtx true = (GET_CODE (XEXP (SET_SRC (x), 0)) == NE
4079 ? XEXP (SET_SRC (x), 1) : XEXP (SET_SRC (x), 2));
4080 rtx false = (GET_CODE (XEXP (SET_SRC (x), 0)) == NE
4081 ? XEXP (SET_SRC (x), 2) : XEXP (SET_SRC (x), 1));
4082 rtx term1 = const0_rtx, term2, term3;
4084 if (GET_CODE (true) == IOR && rtx_equal_p (XEXP (true, 0), false))
4085 term1 = false, true = XEXP (true, 1), false = const0_rtx;
4086 else if (GET_CODE (true) == IOR
4087 && rtx_equal_p (XEXP (true, 1), false))
4088 term1 = false, true = XEXP (true, 0), false = const0_rtx;
4089 else if (GET_CODE (false) == IOR
4090 && rtx_equal_p (XEXP (false, 0), true))
4091 term1 = true, false = XEXP (false, 1), true = const0_rtx;
4092 else if (GET_CODE (false) == IOR
4093 && rtx_equal_p (XEXP (false, 1), true))
4094 term1 = true, false = XEXP (false, 0), true = const0_rtx;
4096 term2 = gen_binary (AND, GET_MODE (SET_SRC (x)),
4097 XEXP (XEXP (SET_SRC (x), 0), 0), true);
4098 term3 = gen_binary (AND, GET_MODE (SET_SRC (x)),
4099 gen_unary (NOT, GET_MODE (SET_SRC (x)),
4100 XEXP (XEXP (SET_SRC (x), 0), 0)),
4104 gen_binary (IOR, GET_MODE (SET_SRC (x)),
4105 gen_binary (IOR, GET_MODE (SET_SRC (x)),
4113 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
4115 x = simplify_and_const_int (x, mode, XEXP (x, 0),
4116 INTVAL (XEXP (x, 1)));
4118 /* If we have (ior (and (X C1) C2)) and the next restart would be
4119 the last, simplify this by making C1 as small as possible
4121 if (n_restarts >= 3 && GET_CODE (x) == IOR
4122 && GET_CODE (XEXP (x, 0)) == AND
4123 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4124 && GET_CODE (XEXP (x, 1)) == CONST_INT)
4126 temp = gen_binary (AND, mode, XEXP (XEXP (x, 0), 0),
4127 GEN_INT (INTVAL (XEXP (XEXP (x, 0), 1))
4128 & ~ INTVAL (XEXP (x, 1))));
4129 return gen_binary (IOR, mode, temp, XEXP (x, 1));
4132 if (GET_CODE (x) != AND)
4136 /* Convert (A | B) & A to A. */
4137 if (GET_CODE (XEXP (x, 0)) == IOR
4138 && (rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1))
4139 || rtx_equal_p (XEXP (XEXP (x, 0), 1), XEXP (x, 1)))
4140 && ! side_effects_p (XEXP (XEXP (x, 0), 0))
4141 && ! side_effects_p (XEXP (XEXP (x, 0), 1)))
4144 /* Convert (A ^ B) & A to A & (~ B) since the latter is often a single
4145 insn (and may simplify more). */
4146 else if (GET_CODE (XEXP (x, 0)) == XOR
4147 && rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1))
4148 && ! side_effects_p (XEXP (x, 1)))
4150 x = gen_binary (AND, mode,
4151 gen_unary (NOT, mode, XEXP (XEXP (x, 0), 1)),
4155 else if (GET_CODE (XEXP (x, 0)) == XOR
4156 && rtx_equal_p (XEXP (XEXP (x, 0), 1), XEXP (x, 1))
4157 && ! side_effects_p (XEXP (x, 1)))
4159 x = gen_binary (AND, mode,
4160 gen_unary (NOT, mode, XEXP (XEXP (x, 0), 0)),
4165 /* Similarly for (~ (A ^ B)) & A. */
4166 else if (GET_CODE (XEXP (x, 0)) == NOT
4167 && GET_CODE (XEXP (XEXP (x, 0), 0)) == XOR
4168 && rtx_equal_p (XEXP (XEXP (XEXP (x, 0), 0), 0), XEXP (x, 1))
4169 && ! side_effects_p (XEXP (x, 1)))
4171 x = gen_binary (AND, mode, XEXP (XEXP (XEXP (x, 0), 0), 1),
4175 else if (GET_CODE (XEXP (x, 0)) == NOT
4176 && GET_CODE (XEXP (XEXP (x, 0), 0)) == XOR
4177 && rtx_equal_p (XEXP (XEXP (XEXP (x, 0), 0), 1), XEXP (x, 1))
4178 && ! side_effects_p (XEXP (x, 1)))
4180 x = gen_binary (AND, mode, XEXP (XEXP (XEXP (x, 0), 0), 0),
4185 /* If we have (and A B) with A not an object but that is known to
4186 be -1 or 0, this is equivalent to the expression
4187 (if_then_else (ne A (const_int 0)) B (const_int 0))
4188 We make this conversion because it may allow further
4189 simplifications and then allow use of conditional move insns.
4190 If the machine doesn't have condition moves, code in case SET
4191 will convert the IF_THEN_ELSE back to the logical operation.
4192 We build the IF_THEN_ELSE here in case further simplification
4193 is possible (e.g., we can convert it to ABS). */
4195 if (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) != 'o'
4196 && ! (GET_CODE (XEXP (x, 0)) == SUBREG
4197 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0)))) == 'o')
4198 && (num_sign_bit_copies (XEXP (x, 0), GET_MODE (XEXP (x, 0)))
4199 == GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))))
4201 rtx op0 = XEXP (x, 0);
4202 rtx op1 = const0_rtx;
4203 enum rtx_code comp_code
4204 = simplify_comparison (NE, &op0, &op1);
4206 x = gen_rtx_combine (IF_THEN_ELSE, mode,
4207 gen_binary (comp_code, VOIDmode, op0, op1),
4208 XEXP (x, 1), const0_rtx);
4212 /* In the following group of tests (and those in case IOR below),
4213 we start with some combination of logical operations and apply
4214 the distributive law followed by the inverse distributive law.
4215 Most of the time, this results in no change. However, if some of
4216 the operands are the same or inverses of each other, simplifications
4219 For example, (and (ior A B) (not B)) can occur as the result of
4220 expanding a bit field assignment. When we apply the distributive
4221 law to this, we get (ior (and (A (not B))) (and (B (not B)))),
4222 which then simplifies to (and (A (not B))). */
4224 /* If we have (and (ior A B) C), apply the distributive law and then
4225 the inverse distributive law to see if things simplify. */
4227 if (GET_CODE (XEXP (x, 0)) == IOR || GET_CODE (XEXP (x, 0)) == XOR)
4229 x = apply_distributive_law
4230 (gen_binary (GET_CODE (XEXP (x, 0)), mode,
4231 gen_binary (AND, mode,
4232 XEXP (XEXP (x, 0), 0), XEXP (x, 1)),
4233 gen_binary (AND, mode,
4234 XEXP (XEXP (x, 0), 1), XEXP (x, 1))));
4235 if (GET_CODE (x) != AND)
4239 if (GET_CODE (XEXP (x, 1)) == IOR || GET_CODE (XEXP (x, 1)) == XOR)
4241 x = apply_distributive_law
4242 (gen_binary (GET_CODE (XEXP (x, 1)), mode,
4243 gen_binary (AND, mode,
4244 XEXP (XEXP (x, 1), 0), XEXP (x, 0)),
4245 gen_binary (AND, mode,
4246 XEXP (XEXP (x, 1), 1), XEXP (x, 0))));
4247 if (GET_CODE (x) != AND)
4251 /* Similarly, taking advantage of the fact that
4252 (and (not A) (xor B C)) == (xor (ior A B) (ior A C)) */
4254 if (GET_CODE (XEXP (x, 0)) == NOT && GET_CODE (XEXP (x, 1)) == XOR)
4256 x = apply_distributive_law
4257 (gen_binary (XOR, mode,
4258 gen_binary (IOR, mode, XEXP (XEXP (x, 0), 0),
4259 XEXP (XEXP (x, 1), 0)),
4260 gen_binary (IOR, mode, XEXP (XEXP (x, 0), 0),
4261 XEXP (XEXP (x, 1), 1))));
4262 if (GET_CODE (x) != AND)
4266 else if (GET_CODE (XEXP (x, 1)) == NOT && GET_CODE (XEXP (x, 0)) == XOR)
4268 x = apply_distributive_law
4269 (gen_binary (XOR, mode,
4270 gen_binary (IOR, mode, XEXP (XEXP (x, 1), 0),
4271 XEXP (XEXP (x, 0), 0)),
4272 gen_binary (IOR, mode, XEXP (XEXP (x, 1), 0),
4273 XEXP (XEXP (x, 0), 1))));
4274 if (GET_CODE (x) != AND)
4280 /* (ior A C) is C if all bits of A that might be nonzero are on in C. */
4281 if (GET_CODE (XEXP (x, 1)) == CONST_INT
4282 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4283 && (nonzero_bits (XEXP (x, 0), mode) & ~ INTVAL (XEXP (x, 1))) == 0)
4286 /* Convert (A & B) | A to A. */
4287 if (GET_CODE (XEXP (x, 0)) == AND
4288 && (rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1))
4289 || rtx_equal_p (XEXP (XEXP (x, 0), 1), XEXP (x, 1)))
4290 && ! side_effects_p (XEXP (XEXP (x, 0), 0))
4291 && ! side_effects_p (XEXP (XEXP (x, 0), 1)))
4294 /* If we have (ior (and A B) C), apply the distributive law and then
4295 the inverse distributive law to see if things simplify. */
4297 if (GET_CODE (XEXP (x, 0)) == AND)
4299 x = apply_distributive_law
4300 (gen_binary (AND, mode,
4301 gen_binary (IOR, mode,
4302 XEXP (XEXP (x, 0), 0), XEXP (x, 1)),
4303 gen_binary (IOR, mode,
4304 XEXP (XEXP (x, 0), 1), XEXP (x, 1))));
4306 if (GET_CODE (x) != IOR)
4310 if (GET_CODE (XEXP (x, 1)) == AND)
4312 x = apply_distributive_law
4313 (gen_binary (AND, mode,
4314 gen_binary (IOR, mode,
4315 XEXP (XEXP (x, 1), 0), XEXP (x, 0)),
4316 gen_binary (IOR, mode,
4317 XEXP (XEXP (x, 1), 1), XEXP (x, 0))));
4319 if (GET_CODE (x) != IOR)
4323 /* Convert (ior (ashift A CX) (lshiftrt A CY)) where CX+CY equals the
4324 mode size to (rotate A CX). */
4326 if (((GET_CODE (XEXP (x, 0)) == ASHIFT
4327 && GET_CODE (XEXP (x, 1)) == LSHIFTRT)
4328 || (GET_CODE (XEXP (x, 1)) == ASHIFT
4329 && GET_CODE (XEXP (x, 0)) == LSHIFTRT))
4330 && rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (XEXP (x, 1), 0))
4331 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4332 && GET_CODE (XEXP (XEXP (x, 1), 1)) == CONST_INT
4333 && (INTVAL (XEXP (XEXP (x, 0), 1)) + INTVAL (XEXP (XEXP (x, 1), 1))
4334 == GET_MODE_BITSIZE (mode)))
4338 if (GET_CODE (XEXP (x, 0)) == ASHIFT)
4339 shift_count = XEXP (XEXP (x, 0), 1);
4341 shift_count = XEXP (XEXP (x, 1), 1);
4342 x = gen_rtx (ROTATE, mode, XEXP (XEXP (x, 0), 0), shift_count);
4348 /* Convert (XOR (NOT x) (NOT y)) to (XOR x y).
4349 Also convert (XOR (NOT x) y) to (NOT (XOR x y)), similarly for
4352 int num_negated = 0;
4353 rtx in1 = XEXP (x, 0), in2 = XEXP (x, 1);
4355 if (GET_CODE (in1) == NOT)
4356 num_negated++, in1 = XEXP (in1, 0);
4357 if (GET_CODE (in2) == NOT)
4358 num_negated++, in2 = XEXP (in2, 0);
4360 if (num_negated == 2)
4362 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4363 SUBST (XEXP (x, 1), XEXP (XEXP (x, 1), 0));
4365 else if (num_negated == 1)
4367 x = gen_unary (NOT, mode,
4368 gen_binary (XOR, mode, in1, in2));
4373 /* Convert (xor (and A B) B) to (and (not A) B). The latter may
4374 correspond to a machine insn or result in further simplifications
4375 if B is a constant. */
4377 if (GET_CODE (XEXP (x, 0)) == AND
4378 && rtx_equal_p (XEXP (XEXP (x, 0), 1), XEXP (x, 1))
4379 && ! side_effects_p (XEXP (x, 1)))
4381 x = gen_binary (AND, mode,
4382 gen_unary (NOT, mode, XEXP (XEXP (x, 0), 0)),
4386 else if (GET_CODE (XEXP (x, 0)) == AND
4387 && rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1))
4388 && ! side_effects_p (XEXP (x, 1)))
4390 x = gen_binary (AND, mode,
4391 gen_unary (NOT, mode, XEXP (XEXP (x, 0), 1)),
4397 #if STORE_FLAG_VALUE == 1
4398 /* (xor (comparison foo bar) (const_int 1)) can become the reversed
4400 if (XEXP (x, 1) == const1_rtx
4401 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
4402 && reversible_comparison_p (XEXP (x, 0)))
4403 return gen_rtx_combine (reverse_condition (GET_CODE (XEXP (x, 0))),
4404 mode, XEXP (XEXP (x, 0), 0),
4405 XEXP (XEXP (x, 0), 1));
4407 /* (lshiftrt foo C) where C is the number of bits in FOO minus 1
4408 is (lt foo (const_int 0)), so we can perform the above
4411 if (XEXP (x, 1) == const1_rtx
4412 && GET_CODE (XEXP (x, 0)) == LSHIFTRT
4413 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4414 && INTVAL (XEXP (XEXP (x, 0), 1)) == GET_MODE_BITSIZE (mode) - 1)
4415 return gen_rtx_combine (GE, mode, XEXP (XEXP (x, 0), 0), const0_rtx);
4418 /* (xor (comparison foo bar) (const_int sign-bit))
4419 when STORE_FLAG_VALUE is the sign bit. */
4420 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4421 && (STORE_FLAG_VALUE
4422 == (HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1))
4423 && XEXP (x, 1) == const_true_rtx
4424 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
4425 && reversible_comparison_p (XEXP (x, 0)))
4426 return gen_rtx_combine (reverse_condition (GET_CODE (XEXP (x, 0))),
4427 mode, XEXP (XEXP (x, 0), 0),
4428 XEXP (XEXP (x, 0), 1));
4432 /* (abs (neg <foo>)) -> (abs <foo>) */
4433 if (GET_CODE (XEXP (x, 0)) == NEG)
4434 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4436 /* If operand is something known to be positive, ignore the ABS. */
4437 if (GET_CODE (XEXP (x, 0)) == FFS || GET_CODE (XEXP (x, 0)) == ABS
4438 || ((GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
4439 <= HOST_BITS_PER_WIDE_INT)
4440 && ((nonzero_bits (XEXP (x, 0), GET_MODE (XEXP (x, 0)))
4441 & ((HOST_WIDE_INT) 1
4442 << (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - 1)))
4447 /* If operand is known to be only -1 or 0, convert ABS to NEG. */
4448 if (num_sign_bit_copies (XEXP (x, 0), mode) == GET_MODE_BITSIZE (mode))
4450 x = gen_rtx_combine (NEG, mode, XEXP (x, 0));
4456 /* (ffs (*_extend <X>)) = (ffs <X>) */
4457 if (GET_CODE (XEXP (x, 0)) == SIGN_EXTEND
4458 || GET_CODE (XEXP (x, 0)) == ZERO_EXTEND)
4459 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4463 /* (float (sign_extend <X>)) = (float <X>). */
4464 if (GET_CODE (XEXP (x, 0)) == SIGN_EXTEND)
4465 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4474 /* If this is a shift by a constant amount, simplify it. */
4475 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
4477 x = simplify_shift_const (x, code, mode, XEXP (x, 0),
4478 INTVAL (XEXP (x, 1)));
4479 if (GET_CODE (x) != code)
4483 #ifdef SHIFT_COUNT_TRUNCATED
4484 else if (GET_CODE (XEXP (x, 1)) != REG)
4486 force_to_mode (XEXP (x, 1), GET_MODE (x),
4487 exact_log2 (GET_MODE_BITSIZE (GET_MODE (x))),
4497 /* We consider ZERO_EXTRACT, SIGN_EXTRACT, and SIGN_EXTEND as "compound
4498 operations" because they can be replaced with two more basic operations.
4499 ZERO_EXTEND is also considered "compound" because it can be replaced with
4500 an AND operation, which is simpler, though only one operation.
4502 The function expand_compound_operation is called with an rtx expression
4503 and will convert it to the appropriate shifts and AND operations,
4504 simplifying at each stage.
4506 The function make_compound_operation is called to convert an expression
4507 consisting of shifts and ANDs into the equivalent compound expression.
4508 It is the inverse of this function, loosely speaking. */
4511 expand_compound_operation (x)
4519 switch (GET_CODE (x))
4524 /* We can't necessarily use a const_int for a multiword mode;
4525 it depends on implicitly extending the value.
4526 Since we don't know the right way to extend it,
4527 we can't tell whether the implicit way is right.
4529 Even for a mode that is no wider than a const_int,
4530 we can't win, because we need to sign extend one of its bits through
4531 the rest of it, and we don't know which bit. */
4532 if (GET_CODE (XEXP (x, 0)) == CONST_INT)
4535 if (! FAKE_EXTEND_SAFE_P (GET_MODE (XEXP (x, 0)), XEXP (x, 0)))
4538 len = GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)));
4539 /* If the inner object has VOIDmode (the only way this can happen
4540 is if it is a ASM_OPERANDS), we can't do anything since we don't
4541 know how much masking to do. */
4550 /* If the operand is a CLOBBER, just return it. */
4551 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
4554 if (GET_CODE (XEXP (x, 1)) != CONST_INT
4555 || GET_CODE (XEXP (x, 2)) != CONST_INT
4556 || GET_MODE (XEXP (x, 0)) == VOIDmode)
4559 len = INTVAL (XEXP (x, 1));
4560 pos = INTVAL (XEXP (x, 2));
4562 /* If this goes outside the object being extracted, replace the object
4563 with a (use (mem ...)) construct that only combine understands
4564 and is used only for this purpose. */
4565 if (len + pos > GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))))
4566 SUBST (XEXP (x, 0), gen_rtx (USE, GET_MODE (x), XEXP (x, 0)));
4569 pos = GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - len - pos;
4577 /* If we reach here, we want to return a pair of shifts. The inner
4578 shift is a left shift of BITSIZE - POS - LEN bits. The outer
4579 shift is a right shift of BITSIZE - LEN bits. It is arithmetic or
4580 logical depending on the value of UNSIGNEDP.
4582 If this was a ZERO_EXTEND or ZERO_EXTRACT, this pair of shifts will be
4583 converted into an AND of a shift.
4585 We must check for the case where the left shift would have a negative
4586 count. This can happen in a case like (x >> 31) & 255 on machines
4587 that can't shift by a constant. On those machines, we would first
4588 combine the shift with the AND to produce a variable-position
4589 extraction. Then the constant of 31 would be substituted in to produce
4590 a such a position. */
4592 modewidth = GET_MODE_BITSIZE (GET_MODE (x));
4593 if (modewidth >= pos - len)
4594 tem = simplify_shift_const (NULL_RTX, unsignedp ? LSHIFTRT : ASHIFTRT,
4596 simplify_shift_const (NULL_RTX, ASHIFT,
4599 modewidth - pos - len),
4602 else if (unsignedp && len < HOST_BITS_PER_WIDE_INT)
4603 tem = simplify_and_const_int (NULL_RTX, GET_MODE (x),
4604 simplify_shift_const (NULL_RTX, LSHIFTRT,
4607 ((HOST_WIDE_INT) 1 << len) - 1);
4609 /* Any other cases we can't handle. */
4613 /* If we couldn't do this for some reason, return the original
4615 if (GET_CODE (tem) == CLOBBER)
4621 /* X is a SET which contains an assignment of one object into
4622 a part of another (such as a bit-field assignment, STRICT_LOW_PART,
4623 or certain SUBREGS). If possible, convert it into a series of
4626 We half-heartedly support variable positions, but do not at all
4627 support variable lengths. */
4630 expand_field_assignment (x)
4634 rtx pos; /* Always counts from low bit. */
4637 enum machine_mode compute_mode;
4639 /* Loop until we find something we can't simplify. */
4642 if (GET_CODE (SET_DEST (x)) == STRICT_LOW_PART
4643 && GET_CODE (XEXP (SET_DEST (x), 0)) == SUBREG)
4645 inner = SUBREG_REG (XEXP (SET_DEST (x), 0));
4646 len = GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0)));
4649 else if (GET_CODE (SET_DEST (x)) == ZERO_EXTRACT
4650 && GET_CODE (XEXP (SET_DEST (x), 1)) == CONST_INT)
4652 inner = XEXP (SET_DEST (x), 0);
4653 len = INTVAL (XEXP (SET_DEST (x), 1));
4654 pos = XEXP (SET_DEST (x), 2);
4656 /* If the position is constant and spans the width of INNER,
4657 surround INNER with a USE to indicate this. */
4658 if (GET_CODE (pos) == CONST_INT
4659 && INTVAL (pos) + len > GET_MODE_BITSIZE (GET_MODE (inner)))
4660 inner = gen_rtx (USE, GET_MODE (SET_DEST (x)), inner);
4663 if (GET_CODE (pos) == CONST_INT)
4664 pos = GEN_INT (GET_MODE_BITSIZE (GET_MODE (inner)) - len
4666 else if (GET_CODE (pos) == MINUS
4667 && GET_CODE (XEXP (pos, 1)) == CONST_INT
4668 && (INTVAL (XEXP (pos, 1))
4669 == GET_MODE_BITSIZE (GET_MODE (inner)) - len))
4670 /* If position is ADJUST - X, new position is X. */
4671 pos = XEXP (pos, 0);
4673 pos = gen_binary (MINUS, GET_MODE (pos),
4674 GEN_INT (GET_MODE_BITSIZE (GET_MODE (inner))
4680 /* A SUBREG between two modes that occupy the same numbers of words
4681 can be done by moving the SUBREG to the source. */
4682 else if (GET_CODE (SET_DEST (x)) == SUBREG
4683 && (((GET_MODE_SIZE (GET_MODE (SET_DEST (x)))
4684 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
4685 == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x))))
4686 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)))
4688 x = gen_rtx (SET, VOIDmode, SUBREG_REG (SET_DEST (x)),
4689 gen_lowpart_for_combine (GET_MODE (SUBREG_REG (SET_DEST (x))),
4696 while (GET_CODE (inner) == SUBREG && subreg_lowpart_p (inner))
4697 inner = SUBREG_REG (inner);
4699 compute_mode = GET_MODE (inner);
4701 /* Compute a mask of LEN bits, if we can do this on the host machine. */
4702 if (len < HOST_BITS_PER_WIDE_INT)
4703 mask = GEN_INT (((HOST_WIDE_INT) 1 << len) - 1);
4707 /* Now compute the equivalent expression. Make a copy of INNER
4708 for the SET_DEST in case it is a MEM into which we will substitute;
4709 we don't want shared RTL in that case. */
4710 x = gen_rtx (SET, VOIDmode, copy_rtx (inner),
4711 gen_binary (IOR, compute_mode,
4712 gen_binary (AND, compute_mode,
4713 gen_unary (NOT, compute_mode,
4718 gen_binary (ASHIFT, compute_mode,
4719 gen_binary (AND, compute_mode,
4720 gen_lowpart_for_combine
4730 /* Return an RTX for a reference to LEN bits of INNER. If POS_RTX is nonzero,
4731 it is an RTX that represents a variable starting position; otherwise,
4732 POS is the (constant) starting bit position (counted from the LSB).
4734 INNER may be a USE. This will occur when we started with a bitfield
4735 that went outside the boundary of the object in memory, which is
4736 allowed on most machines. To isolate this case, we produce a USE
4737 whose mode is wide enough and surround the MEM with it. The only
4738 code that understands the USE is this routine. If it is not removed,
4739 it will cause the resulting insn not to match.
4741 UNSIGNEDP is non-zero for an unsigned reference and zero for a
4744 IN_DEST is non-zero if this is a reference in the destination of a
4745 SET. This is used when a ZERO_ or SIGN_EXTRACT isn't needed. If non-zero,
4746 a STRICT_LOW_PART will be used, if zero, ZERO_EXTEND or SIGN_EXTEND will
4749 IN_COMPARE is non-zero if we are in a COMPARE. This means that a
4750 ZERO_EXTRACT should be built even for bits starting at bit 0.
4752 MODE is the desired mode of the result (if IN_DEST == 0). */
4755 make_extraction (mode, inner, pos, pos_rtx, len,
4756 unsignedp, in_dest, in_compare)
4757 enum machine_mode mode;
4763 int in_dest, in_compare;
4765 /* This mode describes the size of the storage area
4766 to fetch the overall value from. Within that, we
4767 ignore the POS lowest bits, etc. */
4768 enum machine_mode is_mode = GET_MODE (inner);
4769 enum machine_mode inner_mode;
4770 enum machine_mode wanted_mem_mode = byte_mode;
4771 enum machine_mode pos_mode = word_mode;
4772 enum machine_mode extraction_mode = word_mode;
4773 enum machine_mode tmode = mode_for_size (len, MODE_INT, 1);
4776 rtx orig_pos_rtx = pos_rtx;
4778 /* Get some information about INNER and get the innermost object. */
4779 if (GET_CODE (inner) == USE)
4780 /* (use:SI (mem:QI foo)) stands for (mem:SI foo). */
4781 /* We don't need to adjust the position because we set up the USE
4782 to pretend that it was a full-word object. */
4783 spans_byte = 1, inner = XEXP (inner, 0);
4784 else if (GET_CODE (inner) == SUBREG && subreg_lowpart_p (inner))
4786 /* If going from (subreg:SI (mem:QI ...)) to (mem:QI ...),
4787 consider just the QI as the memory to extract from.
4788 The subreg adds or removes high bits; its mode is
4789 irrelevant to the meaning of this extraction,
4790 since POS and LEN count from the lsb. */
4791 if (GET_CODE (SUBREG_REG (inner)) == MEM)
4792 is_mode = GET_MODE (SUBREG_REG (inner));
4793 inner = SUBREG_REG (inner);
4796 inner_mode = GET_MODE (inner);
4798 if (pos_rtx && GET_CODE (pos_rtx) == CONST_INT)
4799 pos = INTVAL (pos_rtx), pos_rtx = 0;
4801 /* See if this can be done without an extraction. We never can if the
4802 width of the field is not the same as that of some integer mode. For
4803 registers, we can only avoid the extraction if the position is at the
4804 low-order bit and this is either not in the destination or we have the
4805 appropriate STRICT_LOW_PART operation available.
4807 For MEM, we can avoid an extract if the field starts on an appropriate
4808 boundary and we can change the mode of the memory reference. However,
4809 we cannot directly access the MEM if we have a USE and the underlying
4810 MEM is not TMODE. This combination means that MEM was being used in a
4811 context where bits outside its mode were being referenced; that is only
4812 valid in bit-field insns. */
4814 if (tmode != BLKmode
4815 && ! (spans_byte && inner_mode != tmode)
4816 && ((pos_rtx == 0 && pos == 0 && GET_CODE (inner) != MEM
4818 || (GET_CODE (inner) == REG
4819 && (movstrict_optab->handlers[(int) tmode].insn_code
4820 != CODE_FOR_nothing))))
4821 || (GET_CODE (inner) == MEM && pos_rtx == 0
4823 % (STRICT_ALIGNMENT ? GET_MODE_ALIGNMENT (tmode)
4824 : BITS_PER_UNIT)) == 0
4825 /* We can't do this if we are widening INNER_MODE (it
4826 may not be aligned, for one thing). */
4827 && GET_MODE_BITSIZE (inner_mode) >= GET_MODE_BITSIZE (tmode)
4828 && (inner_mode == tmode
4829 || (! mode_dependent_address_p (XEXP (inner, 0))
4830 && ! MEM_VOLATILE_P (inner))))))
4832 /* If INNER is a MEM, make a new MEM that encompasses just the desired
4833 field. If the original and current mode are the same, we need not
4834 adjust the offset. Otherwise, we do if bytes big endian.
4836 If INNER is not a MEM, get a piece consisting of the just the field
4837 of interest (in this case POS must be 0). */
4839 if (GET_CODE (inner) == MEM)
4842 /* POS counts from lsb, but make OFFSET count in memory order. */
4843 if (BYTES_BIG_ENDIAN)
4844 offset = (GET_MODE_BITSIZE (is_mode) - len - pos) / BITS_PER_UNIT;
4846 offset = pos / BITS_PER_UNIT;
4848 new = gen_rtx (MEM, tmode, plus_constant (XEXP (inner, 0), offset));
4849 RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (inner);
4850 MEM_VOLATILE_P (new) = MEM_VOLATILE_P (inner);
4851 MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (inner);
4853 else if (GET_CODE (inner) == REG)
4854 /* We can't call gen_lowpart_for_combine here since we always want
4855 a SUBREG and it would sometimes return a new hard register. */
4856 new = gen_rtx (SUBREG, tmode, inner,
4858 && GET_MODE_SIZE (inner_mode) > UNITS_PER_WORD
4859 ? ((GET_MODE_SIZE (inner_mode) - GET_MODE_SIZE (tmode))
4863 new = force_to_mode (inner, tmode, len, NULL_RTX);
4865 /* If this extraction is going into the destination of a SET,
4866 make a STRICT_LOW_PART unless we made a MEM. */
4869 return (GET_CODE (new) == MEM ? new
4870 : (GET_CODE (new) != SUBREG
4871 ? gen_rtx (CLOBBER, tmode, const0_rtx)
4872 : gen_rtx_combine (STRICT_LOW_PART, VOIDmode, new)));
4874 /* Otherwise, sign- or zero-extend unless we already are in the
4877 return (mode == tmode ? new
4878 : gen_rtx_combine (unsignedp ? ZERO_EXTEND : SIGN_EXTEND,
4882 /* Unless this is a COMPARE or we have a funny memory reference,
4883 don't do anything with zero-extending field extracts starting at
4884 the low-order bit since they are simple AND operations. */
4885 if (pos_rtx == 0 && pos == 0 && ! in_dest
4886 && ! in_compare && ! spans_byte && unsignedp)
4889 /* Get the mode to use should INNER be a MEM, the mode for the position,
4890 and the mode for the result. */
4894 wanted_mem_mode = insn_operand_mode[(int) CODE_FOR_insv][0];
4895 pos_mode = insn_operand_mode[(int) CODE_FOR_insv][2];
4896 extraction_mode = insn_operand_mode[(int) CODE_FOR_insv][3];
4901 if (! in_dest && unsignedp)
4903 wanted_mem_mode = insn_operand_mode[(int) CODE_FOR_extzv][1];
4904 pos_mode = insn_operand_mode[(int) CODE_FOR_extzv][3];
4905 extraction_mode = insn_operand_mode[(int) CODE_FOR_extzv][0];
4910 if (! in_dest && ! unsignedp)
4912 wanted_mem_mode = insn_operand_mode[(int) CODE_FOR_extv][1];
4913 pos_mode = insn_operand_mode[(int) CODE_FOR_extv][3];
4914 extraction_mode = insn_operand_mode[(int) CODE_FOR_extv][0];
4918 /* Never narrow an object, since that might not be safe. */
4920 if (mode != VOIDmode
4921 && GET_MODE_SIZE (extraction_mode) < GET_MODE_SIZE (mode))
4922 extraction_mode = mode;
4924 if (pos_rtx && GET_MODE (pos_rtx) != VOIDmode
4925 && GET_MODE_SIZE (pos_mode) < GET_MODE_SIZE (GET_MODE (pos_rtx)))
4926 pos_mode = GET_MODE (pos_rtx);
4928 /* If this is not from memory or we have to change the mode of memory and
4929 cannot, the desired mode is EXTRACTION_MODE. */
4930 if (GET_CODE (inner) != MEM
4931 || (inner_mode != wanted_mem_mode
4932 && (mode_dependent_address_p (XEXP (inner, 0))
4933 || MEM_VOLATILE_P (inner))))
4934 wanted_mem_mode = extraction_mode;
4937 /* If position is constant, compute new position. Otherwise, build
4940 pos = (MAX (GET_MODE_BITSIZE (is_mode), GET_MODE_BITSIZE (wanted_mem_mode))
4944 = gen_rtx_combine (MINUS, GET_MODE (pos_rtx),
4945 GEN_INT (MAX (GET_MODE_BITSIZE (is_mode),
4946 GET_MODE_BITSIZE (wanted_mem_mode))
4951 /* If INNER has a wider mode, make it smaller. If this is a constant
4952 extract, try to adjust the byte to point to the byte containing
4954 if (wanted_mem_mode != VOIDmode
4955 && GET_MODE_SIZE (wanted_mem_mode) < GET_MODE_SIZE (is_mode)
4956 && ((GET_CODE (inner) == MEM
4957 && (inner_mode == wanted_mem_mode
4958 || (! mode_dependent_address_p (XEXP (inner, 0))
4959 && ! MEM_VOLATILE_P (inner))))))
4963 /* The computations below will be correct if the machine is big
4964 endian in both bits and bytes or little endian in bits and bytes.
4965 If it is mixed, we must adjust. */
4967 /* If bytes are big endian and we had a paradoxical SUBREG, we must
4968 adjust OFFSET to compensate. */
4969 #if BYTES_BIG_ENDIAN
4971 && GET_MODE_SIZE (inner_mode) < GET_MODE_SIZE (is_mode))
4972 offset -= GET_MODE_SIZE (is_mode) - GET_MODE_SIZE (inner_mode);
4975 /* If this is a constant position, we can move to the desired byte. */
4978 offset += pos / BITS_PER_UNIT;
4979 pos %= GET_MODE_BITSIZE (wanted_mem_mode);
4982 #if BYTES_BIG_ENDIAN != BITS_BIG_ENDIAN
4983 if (! spans_byte && is_mode != wanted_mem_mode)
4984 offset = (GET_MODE_SIZE (is_mode)
4985 - GET_MODE_SIZE (wanted_mem_mode) - offset);
4988 if (offset != 0 || inner_mode != wanted_mem_mode)
4990 rtx newmem = gen_rtx (MEM, wanted_mem_mode,
4991 plus_constant (XEXP (inner, 0), offset));
4992 RTX_UNCHANGING_P (newmem) = RTX_UNCHANGING_P (inner);
4993 MEM_VOLATILE_P (newmem) = MEM_VOLATILE_P (inner);
4994 MEM_IN_STRUCT_P (newmem) = MEM_IN_STRUCT_P (inner);
4999 /* If INNER is not memory, we can always get it into the proper mode. */
5000 else if (GET_CODE (inner) != MEM)
5001 inner = force_to_mode (inner, extraction_mode,
5002 (pos < 0 ? GET_MODE_BITSIZE (extraction_mode)
5006 /* Adjust mode of POS_RTX, if needed. If we want a wider mode, we
5007 have to zero extend. Otherwise, we can just use a SUBREG. */
5009 && GET_MODE_SIZE (pos_mode) > GET_MODE_SIZE (GET_MODE (pos_rtx)))
5010 pos_rtx = gen_rtx_combine (ZERO_EXTEND, pos_mode, pos_rtx);
5011 else if (pos_rtx != 0
5012 && GET_MODE_SIZE (pos_mode) < GET_MODE_SIZE (GET_MODE (pos_rtx)))
5013 pos_rtx = gen_lowpart_for_combine (pos_mode, pos_rtx);
5015 /* Make POS_RTX unless we already have it and it is correct. If we don't
5016 have a POS_RTX but we do have an ORIG_POS_RTX, the latter must
5018 if (pos_rtx == 0 && orig_pos_rtx != 0 && INTVAL (orig_pos_rtx) == pos)
5019 pos_rtx = orig_pos_rtx;
5021 else if (pos_rtx == 0)
5022 pos_rtx = GEN_INT (pos);
5024 /* Make the required operation. See if we can use existing rtx. */
5025 new = gen_rtx_combine (unsignedp ? ZERO_EXTRACT : SIGN_EXTRACT,
5026 extraction_mode, inner, GEN_INT (len), pos_rtx);
5028 new = gen_lowpart_for_combine (mode, new);
5033 /* Look at the expression rooted at X. Look for expressions
5034 equivalent to ZERO_EXTRACT, SIGN_EXTRACT, ZERO_EXTEND, SIGN_EXTEND.
5035 Form these expressions.
5037 Return the new rtx, usually just X.
5039 Also, for machines like the Vax that don't have logical shift insns,
5040 try to convert logical to arithmetic shift operations in cases where
5041 they are equivalent. This undoes the canonicalizations to logical
5042 shifts done elsewhere.
5044 We try, as much as possible, to re-use rtl expressions to save memory.
5046 IN_CODE says what kind of expression we are processing. Normally, it is
5047 SET. In a memory address (inside a MEM, PLUS or minus, the latter two
5048 being kludges), it is MEM. When processing the arguments of a comparison
5049 or a COMPARE against zero, it is COMPARE. */
5052 make_compound_operation (x, in_code)
5054 enum rtx_code in_code;
5056 enum rtx_code code = GET_CODE (x);
5057 enum machine_mode mode = GET_MODE (x);
5058 int mode_width = GET_MODE_BITSIZE (mode);
5059 enum rtx_code next_code;
5065 /* Select the code to be used in recursive calls. Once we are inside an
5066 address, we stay there. If we have a comparison, set to COMPARE,
5067 but once inside, go back to our default of SET. */
5069 next_code = (code == MEM || code == PLUS || code == MINUS ? MEM
5070 : ((code == COMPARE || GET_RTX_CLASS (code) == '<')
5071 && XEXP (x, 1) == const0_rtx) ? COMPARE
5072 : in_code == COMPARE ? SET : in_code);
5074 /* Process depending on the code of this operation. If NEW is set
5075 non-zero, it will be returned. */
5081 /* Convert shifts by constants into multiplications if inside
5083 if (in_code == MEM && GET_CODE (XEXP (x, 1)) == CONST_INT
5084 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT
5085 && INTVAL (XEXP (x, 1)) >= 0)
5087 new = make_compound_operation (XEXP (x, 0), next_code);
5088 new = gen_rtx_combine (MULT, mode, new,
5089 GEN_INT ((HOST_WIDE_INT) 1
5090 << INTVAL (XEXP (x, 1))));
5095 /* If the second operand is not a constant, we can't do anything
5097 if (GET_CODE (XEXP (x, 1)) != CONST_INT)
5100 /* If the constant is a power of two minus one and the first operand
5101 is a logical right shift, make an extraction. */
5102 if (GET_CODE (XEXP (x, 0)) == LSHIFTRT
5103 && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0)
5105 new = make_compound_operation (XEXP (XEXP (x, 0), 0), next_code);
5106 new = make_extraction (mode, new, 0, XEXP (XEXP (x, 0), 1), i, 1,
5107 0, in_code == COMPARE);
5110 /* Same as previous, but for (subreg (lshiftrt ...)) in first op. */
5111 else if (GET_CODE (XEXP (x, 0)) == SUBREG
5112 && subreg_lowpart_p (XEXP (x, 0))
5113 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == LSHIFTRT
5114 && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0)
5116 new = make_compound_operation (XEXP (SUBREG_REG (XEXP (x, 0)), 0),
5118 new = make_extraction (GET_MODE (SUBREG_REG (XEXP (x, 0))), new, 0,
5119 XEXP (SUBREG_REG (XEXP (x, 0)), 1), i, 1,
5120 0, in_code == COMPARE);
5123 /* If we are have (and (rotate X C) M) and C is larger than the number
5124 of bits in M, this is an extraction. */
5126 else if (GET_CODE (XEXP (x, 0)) == ROTATE
5127 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
5128 && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0
5129 && i <= INTVAL (XEXP (XEXP (x, 0), 1)))
5131 new = make_compound_operation (XEXP (XEXP (x, 0), 0), next_code);
5132 new = make_extraction (mode, new,
5133 (GET_MODE_BITSIZE (mode)
5134 - INTVAL (XEXP (XEXP (x, 0), 1))),
5135 NULL_RTX, i, 1, 0, in_code == COMPARE);
5138 /* On machines without logical shifts, if the operand of the AND is
5139 a logical shift and our mask turns off all the propagated sign
5140 bits, we can replace the logical shift with an arithmetic shift. */
5141 else if (ashr_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing
5142 && (lshr_optab->handlers[(int) mode].insn_code
5143 == CODE_FOR_nothing)
5144 && GET_CODE (XEXP (x, 0)) == LSHIFTRT
5145 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
5146 && INTVAL (XEXP (XEXP (x, 0), 1)) >= 0
5147 && INTVAL (XEXP (XEXP (x, 0), 1)) < HOST_BITS_PER_WIDE_INT
5148 && mode_width <= HOST_BITS_PER_WIDE_INT)
5150 unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode);
5152 mask >>= INTVAL (XEXP (XEXP (x, 0), 1));
5153 if ((INTVAL (XEXP (x, 1)) & ~mask) == 0)
5155 gen_rtx_combine (ASHIFTRT, mode,
5156 make_compound_operation (XEXP (XEXP (x, 0), 0),
5158 XEXP (XEXP (x, 0), 1)));
5161 /* If the constant is one less than a power of two, this might be
5162 representable by an extraction even if no shift is present.
5163 If it doesn't end up being a ZERO_EXTEND, we will ignore it unless
5164 we are in a COMPARE. */
5165 else if ((i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0)
5166 new = make_extraction (mode,
5167 make_compound_operation (XEXP (x, 0),
5169 0, NULL_RTX, i, 1, 0, in_code == COMPARE);
5171 /* If we are in a comparison and this is an AND with a power of two,
5172 convert this into the appropriate bit extract. */
5173 else if (in_code == COMPARE
5174 && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0)
5175 new = make_extraction (mode,
5176 make_compound_operation (XEXP (x, 0),
5178 i, NULL_RTX, 1, 1, 0, 1);
5183 /* If the sign bit is known to be zero, replace this with an
5184 arithmetic shift. */
5185 if (ashr_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing
5186 && lshr_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing
5187 && mode_width <= HOST_BITS_PER_WIDE_INT
5188 && (nonzero_bits (XEXP (x, 0), mode) & (1 << (mode_width - 1))) == 0)
5190 new = gen_rtx_combine (ASHIFTRT, mode,
5191 make_compound_operation (XEXP (x, 0),
5197 /* ... fall through ... */
5200 /* If we have (ashiftrt (ashift foo C1) C2) with C2 >= C1,
5201 this is a SIGN_EXTRACT. */
5202 if (GET_CODE (XEXP (x, 1)) == CONST_INT
5203 && GET_CODE (XEXP (x, 0)) == ASHIFT
5204 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
5205 && INTVAL (XEXP (x, 1)) >= INTVAL (XEXP (XEXP (x, 0), 1)))
5207 new = make_compound_operation (XEXP (XEXP (x, 0), 0), next_code);
5208 new = make_extraction (mode, new,
5209 (INTVAL (XEXP (x, 1))
5210 - INTVAL (XEXP (XEXP (x, 0), 1))),
5211 NULL_RTX, mode_width - INTVAL (XEXP (x, 1)),
5212 code == LSHIFTRT, 0, in_code == COMPARE);
5215 /* Similarly if we have (ashifrt (OP (ashift foo C1) C3) C2). In these
5216 cases, we are better off returning a SIGN_EXTEND of the operation. */
5218 if (GET_CODE (XEXP (x, 1)) == CONST_INT
5219 && (GET_CODE (XEXP (x, 0)) == IOR || GET_CODE (XEXP (x, 0)) == AND
5220 || GET_CODE (XEXP (x, 0)) == XOR
5221 || GET_CODE (XEXP (x, 0)) == PLUS)
5222 && GET_CODE (XEXP (XEXP (x, 0), 0)) == ASHIFT
5223 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT
5224 && INTVAL (XEXP (XEXP (XEXP (x, 0), 0), 1)) < HOST_BITS_PER_WIDE_INT
5225 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
5226 && 0 == (INTVAL (XEXP (XEXP (x, 0), 1))
5227 & (((HOST_WIDE_INT) 1
5228 << (MIN (INTVAL (XEXP (XEXP (XEXP (x, 0), 0), 1)),
5229 INTVAL (XEXP (x, 1)))
5232 rtx c1 = XEXP (XEXP (XEXP (x, 0), 0), 1);
5233 rtx c2 = XEXP (x, 1);
5234 rtx c3 = XEXP (XEXP (x, 0), 1);
5235 HOST_WIDE_INT newop1;
5236 rtx inner = XEXP (XEXP (XEXP (x, 0), 0), 0);
5238 /* If C1 > C2, INNER needs to have the shift performed on it
5240 if (INTVAL (c1) > INTVAL (c2))
5242 inner = gen_binary (ASHIFT, mode, inner,
5243 GEN_INT (INTVAL (c1) - INTVAL (c2)));
5247 newop1 = INTVAL (c3) >> INTVAL (c1);
5248 new = make_compound_operation (inner,
5249 GET_CODE (XEXP (x, 0)) == PLUS
5250 ? MEM : GET_CODE (XEXP (x, 0)));
5251 new = make_extraction (mode,
5252 gen_binary (GET_CODE (XEXP (x, 0)), mode, new,
5254 INTVAL (c2) - INTVAL (c1),
5255 NULL_RTX, mode_width - INTVAL (c2),
5256 code == LSHIFTRT, 0, in_code == COMPARE);
5259 /* Similarly for (ashiftrt (neg (ashift FOO C1)) C2). */
5260 if (GET_CODE (XEXP (x, 1)) == CONST_INT
5261 && GET_CODE (XEXP (x, 0)) == NEG
5262 && GET_CODE (XEXP (XEXP (x, 0), 0)) == ASHIFT
5263 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT
5264 && INTVAL (XEXP (x, 1)) >= INTVAL (XEXP (XEXP (XEXP (x, 0), 0), 1)))
5266 new = make_compound_operation (XEXP (XEXP (XEXP (x, 0), 0), 0),
5268 new = make_extraction (mode,
5269 gen_unary (GET_CODE (XEXP (x, 0)), mode,
5271 (INTVAL (XEXP (x, 1))
5272 - INTVAL (XEXP (XEXP (XEXP (x, 0), 0), 1))),
5273 NULL_RTX, mode_width - INTVAL (XEXP (x, 1)),
5274 code == LSHIFTRT, 0, in_code == COMPARE);
5279 /* Call ourselves recursively on the inner expression. If we are
5280 narrowing the object and it has a different RTL code from
5281 what it originally did, do this SUBREG as a force_to_mode. */
5283 tem = make_compound_operation (SUBREG_REG (x), in_code);
5284 if (GET_CODE (tem) != GET_CODE (SUBREG_REG (x))
5285 && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (tem))
5286 && subreg_lowpart_p (x))
5288 rtx newer = force_to_mode (tem, mode,
5289 GET_MODE_BITSIZE (mode), NULL_RTX);
5291 /* If we have something other than a SUBREG, we might have
5292 done an expansion, so rerun outselves. */
5293 if (GET_CODE (newer) != SUBREG)
5294 newer = make_compound_operation (newer, in_code);
5302 x = gen_lowpart_for_combine (mode, new);
5303 code = GET_CODE (x);
5306 /* Now recursively process each operand of this operation. */
5307 fmt = GET_RTX_FORMAT (code);
5308 for (i = 0; i < GET_RTX_LENGTH (code); i++)
5311 new = make_compound_operation (XEXP (x, i), next_code);
5312 SUBST (XEXP (x, i), new);
5318 /* Given M see if it is a value that would select a field of bits
5319 within an item, but not the entire word. Return -1 if not.
5320 Otherwise, return the starting position of the field, where 0 is the
5323 *PLEN is set to the length of the field. */
5326 get_pos_from_mask (m, plen)
5327 unsigned HOST_WIDE_INT m;
5330 /* Get the bit number of the first 1 bit from the right, -1 if none. */
5331 int pos = exact_log2 (m & - m);
5336 /* Now shift off the low-order zero bits and see if we have a power of
5338 *plen = exact_log2 ((m >> pos) + 1);
5346 /* Rewrite X so that it is an expression in MODE. We only care about the
5347 low-order BITS bits so we can ignore AND operations that just clear
5350 Also, if REG is non-zero and X is a register equal in value to REG,
5351 replace X with REG. */
5354 force_to_mode (x, mode, bits, reg)
5356 enum machine_mode mode;
5360 enum rtx_code code = GET_CODE (x);
5361 enum machine_mode op_mode = mode;
5363 /* If X is narrower than MODE or if BITS is larger than the size of MODE,
5364 just get X in the proper mode. */
5366 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (mode)
5367 || bits > GET_MODE_BITSIZE (mode))
5368 return gen_lowpart_for_combine (mode, x);
5376 x = expand_compound_operation (x);
5377 if (GET_CODE (x) != code)
5378 return force_to_mode (x, mode, bits, reg);
5382 if (reg != 0 && (rtx_equal_p (get_last_value (reg), x)
5383 || rtx_equal_p (reg, get_last_value (x))))
5388 if (bits < HOST_BITS_PER_WIDE_INT)
5389 x = GEN_INT (INTVAL (x) & (((HOST_WIDE_INT) 1 << bits) - 1));
5393 /* Ignore low-order SUBREGs. */
5394 if (subreg_lowpart_p (x))
5395 return force_to_mode (SUBREG_REG (x), mode, bits, reg);
5399 /* If this is an AND with a constant. Otherwise, we fall through to
5400 do the general binary case. */
5402 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
5404 HOST_WIDE_INT mask = INTVAL (XEXP (x, 1));
5405 int len = exact_log2 (mask + 1);
5406 rtx op = XEXP (x, 0);
5408 /* If this is masking some low-order bits, we may be able to
5409 impose a stricter constraint on what bits of the operand are
5412 op = force_to_mode (op, mode, len > 0 ? MIN (len, bits) : bits,
5415 if (bits < HOST_BITS_PER_WIDE_INT)
5416 mask &= ((HOST_WIDE_INT) 1 << bits) - 1;
5418 /* If we have no AND in MODE, use the original mode for the
5421 if (and_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5422 op_mode = GET_MODE (x);
5424 x = simplify_and_const_int (x, op_mode, op, mask);
5426 /* If X is still an AND, see if it is an AND with a mask that
5427 is just some low-order bits. If so, and it is BITS wide (it
5428 can't be wider), we don't need it. */
5430 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT
5431 && bits < HOST_BITS_PER_WIDE_INT
5432 && INTVAL (XEXP (x, 1)) == ((HOST_WIDE_INT) 1 << bits) - 1)
5438 /* ... fall through ... */
5445 /* For most binary operations, just propagate into the operation and
5446 change the mode if we have an operation of that mode. */
5449 && add_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5451 && sub_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5452 || (code == MULT && (smul_optab->handlers[(int) mode].insn_code
5453 == CODE_FOR_nothing))
5455 && and_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5457 && ior_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5458 || (code == XOR && (xor_optab->handlers[(int) mode].insn_code
5459 == CODE_FOR_nothing)))
5460 op_mode = GET_MODE (x);
5462 x = gen_binary (code, op_mode,
5463 gen_lowpart_for_combine (op_mode,
5464 force_to_mode (XEXP (x, 0),
5467 gen_lowpart_for_combine (op_mode,
5468 force_to_mode (XEXP (x, 1),
5475 /* For left shifts, do the same, but just for the first operand.
5476 However, we cannot do anything with shifts where we cannot
5477 guarantee that the counts are smaller than the size of the mode
5478 because such a count will have a different meaning in a
5481 If we can narrow the shift and know the count, we need even fewer
5482 bits of the first operand. */
5484 if (! (GET_CODE (XEXP (x, 1)) == CONST_INT
5485 && INTVAL (XEXP (x, 1)) < GET_MODE_BITSIZE (mode))
5486 && ! (GET_MODE (XEXP (x, 1)) != VOIDmode
5487 && (nonzero_bits (XEXP (x, 1), GET_MODE (XEXP (x, 1)))
5488 < (unsigned HOST_WIDE_INT) GET_MODE_BITSIZE (mode))))
5491 if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) < bits)
5492 bits -= INTVAL (XEXP (x, 1));
5495 && ashl_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5496 || (code == LSHIFT && (lshl_optab->handlers[(int) mode].insn_code
5497 == CODE_FOR_nothing)))
5498 op_mode = GET_MODE (x);
5500 x = gen_binary (code, op_mode,
5501 gen_lowpart_for_combine (op_mode,
5502 force_to_mode (XEXP (x, 0),
5509 /* Here we can only do something if the shift count is a constant and
5510 the count plus BITS is no larger than the width of MODE. In that
5511 case, we can do the shift in MODE. */
5513 if (GET_CODE (XEXP (x, 1)) == CONST_INT
5514 && INTVAL (XEXP (x, 1)) + bits <= GET_MODE_BITSIZE (mode))
5516 rtx inner = force_to_mode (XEXP (x, 0), mode,
5517 bits + INTVAL (XEXP (x, 1)), reg);
5519 if (lshr_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5520 op_mode = GET_MODE (x);
5522 x = gen_binary (LSHIFTRT, op_mode,
5523 gen_lowpart_for_combine (op_mode, inner),
5529 /* If this is a sign-extension operation that just affects bits
5530 we don't care about, remove it. */
5532 if (GET_CODE (XEXP (x, 1)) == CONST_INT
5533 && INTVAL (XEXP (x, 1)) >= 0
5534 && INTVAL (XEXP (x, 1)) <= GET_MODE_BITSIZE (GET_MODE (x)) - bits
5535 && GET_CODE (XEXP (x, 0)) == ASHIFT
5536 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
5537 && INTVAL (XEXP (XEXP (x, 0), 1)) == INTVAL (XEXP (x, 1)))
5538 return force_to_mode (XEXP (XEXP (x, 0), 0), mode, bits, reg);
5544 && neg_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
5545 || (code == NOT && (one_cmpl_optab->handlers[(int) mode].insn_code
5546 == CODE_FOR_nothing)))
5547 op_mode = GET_MODE (x);
5549 /* Handle these similarly to the way we handle most binary operations. */
5550 x = gen_unary (code, op_mode,
5551 gen_lowpart_for_combine (op_mode,
5552 force_to_mode (XEXP (x, 0), mode,
5557 /* We have no way of knowing if the IF_THEN_ELSE can itself be
5558 written in a narrower mode. We play it safe and do not do so. */
5561 gen_lowpart_for_combine (GET_MODE (x),
5562 force_to_mode (XEXP (x, 1), mode,
5565 gen_lowpart_for_combine (GET_MODE (x),
5566 force_to_mode (XEXP (x, 2), mode,
5571 /* Ensure we return a value of the proper mode. */
5572 return gen_lowpart_for_combine (mode, x);
5575 /* Return the value of expression X given the fact that condition COND
5576 is known to be true when applied to REG as its first operand and VAL
5577 as its second. X is known to not be shared and so can be modified in
5580 We only handle the simplest cases, and specifically those cases that
5581 arise with IF_THEN_ELSE expressions. */
5584 known_cond (x, cond, reg, val)
5589 enum rtx_code code = GET_CODE (x);
5594 if (side_effects_p (x))
5597 if (cond == EQ && rtx_equal_p (x, reg))
5600 /* If X is (abs REG) and we know something about REG's relationship
5601 with zero, we may be able to simplify this. */
5603 if (code == ABS && rtx_equal_p (XEXP (x, 0), reg) && val == const0_rtx)
5606 case GE: case GT: case EQ:
5609 return gen_unary (NEG, GET_MODE (XEXP (x, 0)), XEXP (x, 0));
5612 /* The only other cases we handle are MIN, MAX, and comparisons if the
5613 operands are the same as REG and VAL. */
5615 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == 'c')
5617 if (rtx_equal_p (XEXP (x, 0), val))
5618 cond = swap_condition (cond), temp = val, val = reg, reg = temp;
5620 if (rtx_equal_p (XEXP (x, 0), reg) && rtx_equal_p (XEXP (x, 1), val))
5622 if (GET_RTX_CLASS (code) == '<')
5623 return (comparison_dominates_p (cond, code) ? const_true_rtx
5624 : (comparison_dominates_p (cond,
5625 reverse_condition (code))
5628 else if (code == SMAX || code == SMIN
5629 || code == UMIN || code == UMAX)
5631 int unsignedp = (code == UMIN || code == UMAX);
5633 if (code == SMAX || code == UMAX)
5634 cond = reverse_condition (cond);
5639 return unsignedp ? x : XEXP (x, 1);
5641 return unsignedp ? x : XEXP (x, 0);
5643 return unsignedp ? XEXP (x, 1) : x;
5645 return unsignedp ? XEXP (x, 0) : x;
5651 fmt = GET_RTX_FORMAT (code);
5652 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5655 SUBST (XEXP (x, i), known_cond (XEXP (x, i), cond, reg, val));
5656 else if (fmt[i] == 'E')
5657 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5658 SUBST (XVECEXP (x, i, j), known_cond (XVECEXP (x, i, j),
5665 /* See if X, a SET operation, can be rewritten as a bit-field assignment.
5666 Return that assignment if so.
5668 We only handle the most common cases. */
5671 make_field_assignment (x)
5674 rtx dest = SET_DEST (x);
5675 rtx src = SET_SRC (x);
5681 enum machine_mode mode;
5683 /* If SRC was (and (not (ashift (const_int 1) POS)) DEST), this is
5684 a clear of a one-bit field. We will have changed it to
5685 (and (rotate (const_int -2) POS) DEST), so check for that. Also check
5688 if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == ROTATE
5689 && GET_CODE (XEXP (XEXP (src, 0), 0)) == CONST_INT
5690 && INTVAL (XEXP (XEXP (src, 0), 0)) == -2
5691 && (rtx_equal_p (dest, XEXP (src, 1))
5692 || rtx_equal_p (dest, get_last_value (XEXP (src, 1)))
5693 || rtx_equal_p (get_last_value (dest), XEXP (src, 1))))
5695 assign = make_extraction (VOIDmode, dest, 0, XEXP (XEXP (src, 0), 1),
5697 return gen_rtx (SET, VOIDmode, assign, const0_rtx);
5700 else if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == SUBREG
5701 && subreg_lowpart_p (XEXP (src, 0))
5702 && (GET_MODE_SIZE (GET_MODE (XEXP (src, 0)))
5703 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (src, 0)))))
5704 && GET_CODE (SUBREG_REG (XEXP (src, 0))) == ROTATE
5705 && INTVAL (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == -2
5706 && (rtx_equal_p (dest, XEXP (src, 1))
5707 || rtx_equal_p (dest, get_last_value (XEXP (src, 1)))
5708 || rtx_equal_p (get_last_value (dest), XEXP (src, 1))))
5710 assign = make_extraction (VOIDmode, dest, 0,
5711 XEXP (SUBREG_REG (XEXP (src, 0)), 1),
5713 return gen_rtx (SET, VOIDmode, assign, const0_rtx);
5716 /* If SRC is (ior (ashift (const_int 1) POS DEST)), this is a set of a
5718 else if (GET_CODE (src) == IOR && GET_CODE (XEXP (src, 0)) == ASHIFT
5719 && XEXP (XEXP (src, 0), 0) == const1_rtx
5720 && (rtx_equal_p (dest, XEXP (src, 1))
5721 || rtx_equal_p (dest, get_last_value (XEXP (src, 1)))
5722 || rtx_equal_p (get_last_value (dest), XEXP (src, 1))))
5724 assign = make_extraction (VOIDmode, dest, 0, XEXP (XEXP (src, 0), 1),
5726 return gen_rtx (SET, VOIDmode, assign, const1_rtx);
5729 /* The other case we handle is assignments into a constant-position
5730 field. They look like (ior (and DEST C1) OTHER). If C1 represents
5731 a mask that has all one bits except for a group of zero bits and
5732 OTHER is known to have zeros where C1 has ones, this is such an
5733 assignment. Compute the position and length from C1. Shift OTHER
5734 to the appropriate position, force it to the required mode, and
5735 make the extraction. Check for the AND in both operands. */
5737 if (GET_CODE (src) == IOR && GET_CODE (XEXP (src, 0)) == AND
5738 && GET_CODE (XEXP (XEXP (src, 0), 1)) == CONST_INT
5739 && (rtx_equal_p (XEXP (XEXP (src, 0), 0), dest)
5740 || rtx_equal_p (XEXP (XEXP (src, 0), 0), get_last_value (dest))
5741 || rtx_equal_p (get_last_value (XEXP (XEXP (src, 0), 1)), dest)))
5742 c1 = INTVAL (XEXP (XEXP (src, 0), 1)), other = XEXP (src, 1);
5743 else if (GET_CODE (src) == IOR && GET_CODE (XEXP (src, 1)) == AND
5744 && GET_CODE (XEXP (XEXP (src, 1), 1)) == CONST_INT
5745 && (rtx_equal_p (XEXP (XEXP (src, 1), 0), dest)
5746 || rtx_equal_p (XEXP (XEXP (src, 1), 0), get_last_value (dest))
5747 || rtx_equal_p (get_last_value (XEXP (XEXP (src, 1), 0)),
5749 c1 = INTVAL (XEXP (XEXP (src, 1), 1)), other = XEXP (src, 0);
5753 pos = get_pos_from_mask (~c1, &len);
5754 if (pos < 0 || pos + len > GET_MODE_BITSIZE (GET_MODE (dest))
5755 || (GET_MODE_BITSIZE (GET_MODE (other)) <= HOST_BITS_PER_WIDE_INT
5756 && (c1 & nonzero_bits (other, GET_MODE (other))) != 0))
5759 assign = make_extraction (VOIDmode, dest, pos, NULL_RTX, len, 1, 1, 0);
5761 /* The mode to use for the source is the mode of the assignment, or of
5762 what is inside a possible STRICT_LOW_PART. */
5763 mode = (GET_CODE (assign) == STRICT_LOW_PART
5764 ? GET_MODE (XEXP (assign, 0)) : GET_MODE (assign));
5766 /* Shift OTHER right POS places and make it the source, restricting it
5767 to the proper length and mode. */
5769 src = force_to_mode (simplify_shift_const (NULL_RTX, LSHIFTRT,
5770 GET_MODE (src), other, pos),
5773 return gen_rtx_combine (SET, VOIDmode, assign, src);
5776 /* See if X is of the form (+ (* a c) (* b c)) and convert to (* (+ a b) c)
5780 apply_distributive_law (x)
5783 enum rtx_code code = GET_CODE (x);
5784 rtx lhs, rhs, other;
5786 enum rtx_code inner_code;
5788 /* Distributivity is not true for floating point.
5789 It can change the value. So don't do it.
5790 -- rms and moshier@world.std.com. */
5791 if (FLOAT_MODE_P (GET_MODE (x)))
5794 /* The outer operation can only be one of the following: */
5795 if (code != IOR && code != AND && code != XOR
5796 && code != PLUS && code != MINUS)
5799 lhs = XEXP (x, 0), rhs = XEXP (x, 1);
5801 /* If either operand is a primitive we can't do anything, so get out fast. */
5802 if (GET_RTX_CLASS (GET_CODE (lhs)) == 'o'
5803 || GET_RTX_CLASS (GET_CODE (rhs)) == 'o')
5806 lhs = expand_compound_operation (lhs);
5807 rhs = expand_compound_operation (rhs);
5808 inner_code = GET_CODE (lhs);
5809 if (inner_code != GET_CODE (rhs))
5812 /* See if the inner and outer operations distribute. */
5819 /* These all distribute except over PLUS. */
5820 if (code == PLUS || code == MINUS)
5825 if (code != PLUS && code != MINUS)
5831 /* These are also multiplies, so they distribute over everything. */
5835 /* Non-paradoxical SUBREGs distributes over all operations, provided
5836 the inner modes and word numbers are the same, this is an extraction
5837 of a low-order part, we don't convert an fp operation to int or
5838 vice versa, and we would not be converting a single-word
5839 operation into a multi-word operation. The latter test is not
5840 required, but it prevents generating unneeded multi-word operations.
5841 Some of the previous tests are redundant given the latter test, but
5842 are retained because they are required for correctness.
5844 We produce the result slightly differently in this case. */
5846 if (GET_MODE (SUBREG_REG (lhs)) != GET_MODE (SUBREG_REG (rhs))
5847 || SUBREG_WORD (lhs) != SUBREG_WORD (rhs)
5848 || ! subreg_lowpart_p (lhs)
5849 || (GET_MODE_CLASS (GET_MODE (lhs))
5850 != GET_MODE_CLASS (GET_MODE (SUBREG_REG (lhs))))
5851 || (GET_MODE_SIZE (GET_MODE (lhs))
5852 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))))
5853 || GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))) > UNITS_PER_WORD)
5856 tem = gen_binary (code, GET_MODE (SUBREG_REG (lhs)),
5857 SUBREG_REG (lhs), SUBREG_REG (rhs));
5858 return gen_lowpart_for_combine (GET_MODE (x), tem);
5864 /* Set LHS and RHS to the inner operands (A and B in the example
5865 above) and set OTHER to the common operand (C in the example).
5866 These is only one way to do this unless the inner operation is
5868 if (GET_RTX_CLASS (inner_code) == 'c'
5869 && rtx_equal_p (XEXP (lhs, 0), XEXP (rhs, 0)))
5870 other = XEXP (lhs, 0), lhs = XEXP (lhs, 1), rhs = XEXP (rhs, 1);
5871 else if (GET_RTX_CLASS (inner_code) == 'c'
5872 && rtx_equal_p (XEXP (lhs, 0), XEXP (rhs, 1)))
5873 other = XEXP (lhs, 0), lhs = XEXP (lhs, 1), rhs = XEXP (rhs, 0);
5874 else if (GET_RTX_CLASS (inner_code) == 'c'
5875 && rtx_equal_p (XEXP (lhs, 1), XEXP (rhs, 0)))
5876 other = XEXP (lhs, 1), lhs = XEXP (lhs, 0), rhs = XEXP (rhs, 1);
5877 else if (rtx_equal_p (XEXP (lhs, 1), XEXP (rhs, 1)))
5878 other = XEXP (lhs, 1), lhs = XEXP (lhs, 0), rhs = XEXP (rhs, 0);
5882 /* Form the new inner operation, seeing if it simplifies first. */
5883 tem = gen_binary (code, GET_MODE (x), lhs, rhs);
5885 /* There is one exception to the general way of distributing:
5886 (a ^ b) | (a ^ c) -> (~a) & (b ^ c) */
5887 if (code == XOR && inner_code == IOR)
5890 other = gen_unary (NOT, GET_MODE (x), other);
5893 /* We may be able to continuing distributing the result, so call
5894 ourselves recursively on the inner operation before forming the
5895 outer operation, which we return. */
5896 return gen_binary (inner_code, GET_MODE (x),
5897 apply_distributive_law (tem), other);
5900 /* We have X, a logical `and' of VAROP with the constant CONSTOP, to be done
5903 Return an equivalent form, if different from X. Otherwise, return X. If
5904 X is zero, we are to always construct the equivalent form. */
5907 simplify_and_const_int (x, mode, varop, constop)
5909 enum machine_mode mode;
5911 unsigned HOST_WIDE_INT constop;
5913 register enum machine_mode tmode;
5915 unsigned HOST_WIDE_INT nonzero;
5917 /* There is a large class of optimizations based on the principle that
5918 some operations produce results where certain bits are known to be zero,
5919 and hence are not significant to the AND. For example, if we have just
5920 done a left shift of one bit, the low-order bit is known to be zero and
5921 hence an AND with a mask of ~1 would not do anything.
5923 At the end of the following loop, we set:
5925 VAROP to be the item to be AND'ed with;
5926 CONSTOP to the constant value to AND it with. */
5930 /* If we ever encounter a mode wider than the host machine's widest
5931 integer size, we can't compute the masks accurately, so give up. */
5932 if (GET_MODE_BITSIZE (GET_MODE (varop)) > HOST_BITS_PER_WIDE_INT)
5935 /* Unless one of the cases below does a `continue',
5936 a `break' will be executed to exit the loop. */
5938 switch (GET_CODE (varop))
5941 /* If VAROP is a (clobber (const_int)), return it since we know
5942 we are generating something that won't match. */
5945 #if ! BITS_BIG_ENDIAN
5947 /* VAROP is a (use (mem ..)) that was made from a bit-field
5948 extraction that spanned the boundary of the MEM. If we are
5949 now masking so it is within that boundary, we don't need the
5951 if ((constop & ~ GET_MODE_MASK (GET_MODE (XEXP (varop, 0)))) == 0)
5953 varop = XEXP (varop, 0);
5960 if (subreg_lowpart_p (varop)
5961 /* We can ignore the effect this SUBREG if it narrows the mode
5962 or, on machines where byte operations extend, if the
5963 constant masks to zero all the bits the mode doesn't have. */
5964 && ((GET_MODE_SIZE (GET_MODE (varop))
5965 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (varop))))
5966 #ifdef BYTE_LOADS_EXTEND
5968 & GET_MODE_MASK (GET_MODE (varop))
5969 & ~ GET_MODE_MASK (GET_MODE (SUBREG_REG (varop)))))
5973 varop = SUBREG_REG (varop);
5982 /* Try to expand these into a series of shifts and then work
5983 with that result. If we can't, for example, if the extract
5984 isn't at a fixed position, give up. */
5985 temp = expand_compound_operation (varop);
5994 if (GET_CODE (XEXP (varop, 1)) == CONST_INT)
5996 constop &= INTVAL (XEXP (varop, 1));
5997 varop = XEXP (varop, 0);
6004 /* If VAROP is (ior (lshiftrt FOO C1) C2), try to commute the IOR and
6005 LSHIFT so we end up with an (and (lshiftrt (ior ...) ...) ...)
6006 operation which may be a bitfield extraction. Ensure
6007 that the constant we form is not wider than the mode of
6010 if (GET_CODE (XEXP (varop, 0)) == LSHIFTRT
6011 && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT
6012 && INTVAL (XEXP (XEXP (varop, 0), 1)) >= 0
6013 && INTVAL (XEXP (XEXP (varop, 0), 1)) < HOST_BITS_PER_WIDE_INT
6014 && GET_CODE (XEXP (varop, 1)) == CONST_INT
6015 && ((INTVAL (XEXP (XEXP (varop, 0), 1))
6016 + floor_log2 (INTVAL (XEXP (varop, 1))))
6017 < GET_MODE_BITSIZE (GET_MODE (varop)))
6018 && (INTVAL (XEXP (varop, 1))
6019 & ~ nonzero_bits (XEXP (varop, 0), GET_MODE (varop)) == 0))
6021 temp = GEN_INT ((INTVAL (XEXP (varop, 1)) & constop)
6022 << INTVAL (XEXP (XEXP (varop, 0), 1)));
6023 temp = gen_binary (GET_CODE (varop), GET_MODE (varop),
6024 XEXP (XEXP (varop, 0), 0), temp);
6025 varop = gen_rtx_combine (LSHIFTRT, GET_MODE (varop),
6026 temp, XEXP (varop, 1));
6030 /* Apply the AND to both branches of the IOR or XOR, then try to
6031 apply the distributive law. This may eliminate operations
6032 if either branch can be simplified because of the AND.
6033 It may also make some cases more complex, but those cases
6034 probably won't match a pattern either with or without this. */
6036 gen_lowpart_for_combine
6037 (mode, apply_distributive_law
6039 (GET_CODE (varop), GET_MODE (varop),
6040 simplify_and_const_int (NULL_RTX, GET_MODE (varop),
6041 XEXP (varop, 0), constop),
6042 simplify_and_const_int (NULL_RTX, GET_MODE (varop),
6043 XEXP (varop, 1), constop))));
6046 /* (and (not FOO)) is (and (xor FOO CONST)), so if FOO is an
6047 LSHIFTRT, we can do the same as above. Ensure that the constant
6048 we form is not wider than the mode of VAROP. */
6050 if (GET_CODE (XEXP (varop, 0)) == LSHIFTRT
6051 && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT
6052 && INTVAL (XEXP (XEXP (varop, 0), 1)) >= 0
6053 && (INTVAL (XEXP (XEXP (varop, 0), 1)) + floor_log2 (constop)
6054 < GET_MODE_BITSIZE (GET_MODE (varop)))
6055 && INTVAL (XEXP (XEXP (varop, 0), 1)) < HOST_BITS_PER_WIDE_INT)
6057 temp = GEN_INT (constop << INTVAL (XEXP (XEXP (varop, 0), 1)));
6058 temp = gen_binary (XOR, GET_MODE (varop),
6059 XEXP (XEXP (varop, 0), 0), temp);
6060 varop = gen_rtx_combine (LSHIFTRT, GET_MODE (varop),
6061 temp, XEXP (XEXP (varop, 0), 1));
6067 /* If we are just looking for the sign bit, we don't need this
6068 shift at all, even if it has a variable count. */
6069 if (constop == ((HOST_WIDE_INT) 1
6070 << (GET_MODE_BITSIZE (GET_MODE (varop)) - 1)))
6072 varop = XEXP (varop, 0);
6076 /* If this is a shift by a constant, get a mask that contains
6077 those bits that are not copies of the sign bit. We then have
6078 two cases: If CONSTOP only includes those bits, this can be
6079 a logical shift, which may allow simplifications. If CONSTOP
6080 is a single-bit field not within those bits, we are requesting
6081 a copy of the sign bit and hence can shift the sign bit to
6082 the appropriate location. */
6083 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
6084 && INTVAL (XEXP (varop, 1)) >= 0
6085 && INTVAL (XEXP (varop, 1)) < HOST_BITS_PER_WIDE_INT)
6089 nonzero = GET_MODE_MASK (GET_MODE (varop));
6090 nonzero >>= INTVAL (XEXP (varop, 1));
6092 if ((constop & ~ nonzero) == 0
6093 || (i = exact_log2 (constop)) >= 0)
6095 varop = simplify_shift_const
6096 (varop, LSHIFTRT, GET_MODE (varop), XEXP (varop, 0),
6097 i < 0 ? INTVAL (XEXP (varop, 1))
6098 : GET_MODE_BITSIZE (GET_MODE (varop)) - 1 - i);
6099 if (GET_CODE (varop) != ASHIFTRT)
6104 /* If our mask is 1, convert this to a LSHIFTRT. This can be done
6105 even if the shift count isn't a constant. */
6107 varop = gen_rtx_combine (LSHIFTRT, GET_MODE (varop),
6108 XEXP (varop, 0), XEXP (varop, 1));
6112 /* If we have (and (lshiftrt FOO C1) C2) where the combination of the
6113 shift and AND produces only copies of the sign bit (C2 is one less
6114 than a power of two), we can do this with just a shift. */
6116 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
6117 && ((INTVAL (XEXP (varop, 1))
6118 + num_sign_bit_copies (XEXP (varop, 0),
6119 GET_MODE (XEXP (varop, 0))))
6120 >= GET_MODE_BITSIZE (GET_MODE (varop)))
6121 && exact_log2 (constop + 1) >= 0)
6123 = gen_rtx_combine (LSHIFTRT, GET_MODE (varop), XEXP (varop, 0),
6124 GEN_INT (GET_MODE_BITSIZE (GET_MODE (varop))
6125 - exact_log2 (constop + 1)));
6129 /* (and (ne FOO 0) CONST) can be (and FOO CONST) if CONST is
6130 included in STORE_FLAG_VALUE and FOO has no bits that might be
6131 nonzero not in CONST. */
6132 if ((constop & ~ STORE_FLAG_VALUE) == 0
6133 && XEXP (varop, 0) == const0_rtx
6134 && (nonzero_bits (XEXP (varop, 0), mode) & ~ constop) == 0)
6136 varop = XEXP (varop, 0);
6142 /* In (and (plus FOO C1) M), if M is a mask that just turns off
6143 low-order bits (as in an alignment operation) and FOO is already
6144 aligned to that boundary, we can convert remove this AND
6145 and possibly the PLUS if it is now adding zero. */
6146 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
6147 && exact_log2 (-constop) >= 0
6148 && (nonzero_bits (XEXP (varop, 0), mode) & ~ constop) == 0)
6150 varop = plus_constant (XEXP (varop, 0),
6151 INTVAL (XEXP (varop, 1)) & constop);
6156 /* ... fall through ... */
6159 /* In (and (plus (and FOO M1) BAR) M2), if M1 and M2 are one
6160 less than powers of two and M2 is narrower than M1, we can
6161 eliminate the inner AND. This occurs when incrementing
6164 if (GET_CODE (XEXP (varop, 0)) == ZERO_EXTRACT
6165 || GET_CODE (XEXP (varop, 0)) == ZERO_EXTEND)
6166 SUBST (XEXP (varop, 0),
6167 expand_compound_operation (XEXP (varop, 0)));
6169 if (GET_CODE (XEXP (varop, 0)) == AND
6170 && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT
6171 && exact_log2 (constop + 1) >= 0
6172 && exact_log2 (INTVAL (XEXP (XEXP (varop, 0), 1)) + 1) >= 0
6173 && (~ INTVAL (XEXP (XEXP (varop, 0), 1)) & constop) == 0)
6174 SUBST (XEXP (varop, 0), XEXP (XEXP (varop, 0), 0));
6181 /* If we have reached a constant, this whole thing is constant. */
6182 if (GET_CODE (varop) == CONST_INT)
6183 return GEN_INT (constop & INTVAL (varop));
6185 /* See what bits may be nonzero in VAROP. Unlike the general case of
6186 a call to nonzero_bits, here we don't care about bits outside
6189 nonzero = nonzero_bits (varop, mode) & GET_MODE_MASK (mode);
6191 /* Turn off all bits in the constant that are known to already be zero.
6192 Thus, if the AND isn't needed at all, we will have CONSTOP == NONZERO_BITS
6193 which is tested below. */
6197 /* If we don't have any bits left, return zero. */
6201 /* Get VAROP in MODE. Try to get a SUBREG if not. Don't make a new SUBREG
6202 if we already had one (just check for the simplest cases). */
6203 if (x && GET_CODE (XEXP (x, 0)) == SUBREG
6204 && GET_MODE (XEXP (x, 0)) == mode
6205 && SUBREG_REG (XEXP (x, 0)) == varop)
6206 varop = XEXP (x, 0);
6208 varop = gen_lowpart_for_combine (mode, varop);
6210 /* If we can't make the SUBREG, try to return what we were given. */
6211 if (GET_CODE (varop) == CLOBBER)
6212 return x ? x : varop;
6214 /* If we are only masking insignificant bits, return VAROP. */
6215 if (constop == nonzero)
6218 /* Otherwise, return an AND. See how much, if any, of X we can use. */
6219 else if (x == 0 || GET_CODE (x) != AND || GET_MODE (x) != mode)
6220 x = gen_rtx_combine (AND, mode, varop, GEN_INT (constop));
6224 if (GET_CODE (XEXP (x, 1)) != CONST_INT
6225 || INTVAL (XEXP (x, 1)) != constop)
6226 SUBST (XEXP (x, 1), GEN_INT (constop));
6228 SUBST (XEXP (x, 0), varop);
6234 /* Given an expression, X, compute which bits in X can be non-zero.
6235 We don't care about bits outside of those defined in MODE.
6237 For most X this is simply GET_MODE_MASK (GET_MODE (MODE)), but if X is
6238 a shift, AND, or zero_extract, we can do better. */
6240 static unsigned HOST_WIDE_INT
6241 nonzero_bits (x, mode)
6243 enum machine_mode mode;
6245 unsigned HOST_WIDE_INT nonzero = GET_MODE_MASK (mode);
6246 unsigned HOST_WIDE_INT inner_nz;
6248 int mode_width = GET_MODE_BITSIZE (mode);
6251 /* If X is wider than MODE, use its mode instead. */
6252 if (GET_MODE_BITSIZE (GET_MODE (x)) > mode_width)
6254 mode = GET_MODE (x);
6255 nonzero = GET_MODE_MASK (mode);
6256 mode_width = GET_MODE_BITSIZE (mode);
6259 if (mode_width > HOST_BITS_PER_WIDE_INT)
6260 /* Our only callers in this case look for single bit values. So
6261 just return the mode mask. Those tests will then be false. */
6264 code = GET_CODE (x);
6268 #ifdef STACK_BOUNDARY
6269 /* If this is the stack pointer, we may know something about its
6270 alignment. If PUSH_ROUNDING is defined, it is possible for the
6271 stack to be momentarily aligned only to that amount, so we pick
6272 the least alignment. */
6274 if (x == stack_pointer_rtx)
6276 int sp_alignment = STACK_BOUNDARY / BITS_PER_UNIT;
6278 #ifdef PUSH_ROUNDING
6279 sp_alignment = MIN (PUSH_ROUNDING (1), sp_alignment);
6282 return nonzero & ~ (sp_alignment - 1);
6286 /* If X is a register whose nonzero bits value is current, use it.
6287 Otherwise, if X is a register whose value we can find, use that
6288 value. Otherwise, use the previously-computed global nonzero bits
6289 for this register. */
6291 if (reg_last_set_value[REGNO (x)] != 0
6292 && reg_last_set_mode[REGNO (x)] == mode
6293 && (reg_n_sets[REGNO (x)] == 1
6294 || reg_last_set_label[REGNO (x)] == label_tick)
6295 && INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid)
6296 return reg_last_set_nonzero_bits[REGNO (x)];
6298 tem = get_last_value (x);
6302 #ifdef SHORT_IMMEDIATES_SIGN_EXTEND
6303 /* If X is narrower than MODE and TEM is a non-negative
6304 constant that would appear negative in the mode of X,
6305 sign-extend it for use in reg_nonzero_bits because some
6306 machines (maybe most) will actually do the sign-extension
6307 and this is the conservative approach.
6309 ??? For 2.5, try to tighten up the MD files in this regard
6310 instead of this kludge. */
6312 if (GET_MODE_BITSIZE (GET_MODE (x)) < mode_width
6313 && GET_CODE (tem) == CONST_INT
6315 && 0 != (INTVAL (tem)
6316 & ((HOST_WIDE_INT) 1
6317 << GET_MODE_BITSIZE (GET_MODE (x)))))
6318 tem = GEN_INT (INTVAL (tem)
6319 | ((HOST_WIDE_INT) (-1)
6320 << GET_MODE_BITSIZE (GET_MODE (x))));
6322 return nonzero_bits (tem, mode);
6324 else if (nonzero_sign_valid && reg_nonzero_bits[REGNO (x)])
6325 return reg_nonzero_bits[REGNO (x)] & nonzero;
6330 #ifdef SHORT_IMMEDIATES_SIGN_EXTEND
6331 /* If X is negative in MODE, sign-extend the value. */
6334 & ((HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (GET_MODE (x)))))
6336 | ((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (GET_MODE (x))));
6341 #ifdef BYTE_LOADS_ZERO_EXTEND
6343 /* In many, if not most, RISC machines, reading a byte from memory
6344 zeros the rest of the register. Noticing that fact saves a lot
6345 of extra zero-extends. */
6346 nonzero &= GET_MODE_MASK (GET_MODE (x));
6350 #if STORE_FLAG_VALUE == 1
6357 if (GET_MODE_CLASS (mode) == MODE_INT)
6360 /* A comparison operation only sets the bits given by its mode. The
6361 rest are set undefined. */
6362 if (GET_MODE_SIZE (GET_MODE (x)) < mode_width)
6363 nonzero |= (GET_MODE_MASK (mode) & ~ GET_MODE_MASK (GET_MODE (x)));
6368 if (num_sign_bit_copies (XEXP (x, 0), GET_MODE (x))
6369 == GET_MODE_BITSIZE (GET_MODE (x)))
6372 if (GET_MODE_SIZE (GET_MODE (x)) < mode_width)
6373 nonzero |= (GET_MODE_MASK (mode) & ~ GET_MODE_MASK (GET_MODE (x)));
6377 if (num_sign_bit_copies (XEXP (x, 0), GET_MODE (x))
6378 == GET_MODE_BITSIZE (GET_MODE (x)))
6383 nonzero &= (nonzero_bits (XEXP (x, 0), mode) & GET_MODE_MASK (mode));
6387 nonzero &= nonzero_bits (XEXP (x, 0), mode);
6388 if (GET_MODE (XEXP (x, 0)) != VOIDmode)
6389 nonzero &= GET_MODE_MASK (GET_MODE (XEXP (x, 0)));
6393 /* If the sign bit is known clear, this is the same as ZERO_EXTEND.
6394 Otherwise, show all the bits in the outer mode but not the inner
6396 inner_nz = nonzero_bits (XEXP (x, 0), mode);
6397 if (GET_MODE (XEXP (x, 0)) != VOIDmode)
6399 inner_nz &= GET_MODE_MASK (GET_MODE (XEXP (x, 0)));
6402 << (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - 1))))
6403 inner_nz |= (GET_MODE_MASK (mode)
6404 & ~ GET_MODE_MASK (GET_MODE (XEXP (x, 0))));
6407 nonzero &= inner_nz;
6411 nonzero &= (nonzero_bits (XEXP (x, 0), mode)
6412 & nonzero_bits (XEXP (x, 1), mode));
6416 case UMIN: case UMAX: case SMIN: case SMAX:
6417 nonzero &= (nonzero_bits (XEXP (x, 0), mode)
6418 | nonzero_bits (XEXP (x, 1), mode));
6421 case PLUS: case MINUS:
6423 case DIV: case UDIV:
6424 case MOD: case UMOD:
6425 /* We can apply the rules of arithmetic to compute the number of
6426 high- and low-order zero bits of these operations. We start by
6427 computing the width (position of the highest-order non-zero bit)
6428 and the number of low-order zero bits for each value. */
6430 unsigned HOST_WIDE_INT nz0 = nonzero_bits (XEXP (x, 0), mode);
6431 unsigned HOST_WIDE_INT nz1 = nonzero_bits (XEXP (x, 1), mode);
6432 int width0 = floor_log2 (nz0) + 1;
6433 int width1 = floor_log2 (nz1) + 1;
6434 int low0 = floor_log2 (nz0 & -nz0);
6435 int low1 = floor_log2 (nz1 & -nz1);
6436 int op0_maybe_minusp = (nz0 & ((HOST_WIDE_INT) 1 << (mode_width - 1)));
6437 int op1_maybe_minusp = (nz1 & ((HOST_WIDE_INT) 1 << (mode_width - 1)));
6438 int result_width = mode_width;
6444 result_width = MAX (width0, width1) + 1;
6445 result_low = MIN (low0, low1);
6448 result_low = MIN (low0, low1);
6451 result_width = width0 + width1;
6452 result_low = low0 + low1;
6455 if (! op0_maybe_minusp && ! op1_maybe_minusp)
6456 result_width = width0;
6459 result_width = width0;
6462 if (! op0_maybe_minusp && ! op1_maybe_minusp)
6463 result_width = MIN (width0, width1);
6464 result_low = MIN (low0, low1);
6467 result_width = MIN (width0, width1);
6468 result_low = MIN (low0, low1);
6472 if (result_width < mode_width)
6473 nonzero &= ((HOST_WIDE_INT) 1 << result_width) - 1;
6476 nonzero &= ~ (((HOST_WIDE_INT) 1 << result_low) - 1);
6481 if (GET_CODE (XEXP (x, 1)) == CONST_INT
6482 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT)
6483 nonzero &= ((HOST_WIDE_INT) 1 << INTVAL (XEXP (x, 1))) - 1;
6487 /* If this is a SUBREG formed for a promoted variable that has
6488 been zero-extended, we know that at least the high-order bits
6489 are zero, though others might be too. */
6491 if (SUBREG_PROMOTED_VAR_P (x) && SUBREG_PROMOTED_UNSIGNED_P (x))
6492 nonzero = (GET_MODE_MASK (GET_MODE (x))
6493 & nonzero_bits (SUBREG_REG (x), GET_MODE (x)));
6495 /* If the inner mode is a single word for both the host and target
6496 machines, we can compute this from which bits of the inner
6497 object might be nonzero. */
6498 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) <= BITS_PER_WORD
6499 && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))
6500 <= HOST_BITS_PER_WIDE_INT))
6502 nonzero &= nonzero_bits (SUBREG_REG (x), mode);
6503 #ifndef BYTE_LOADS_EXTEND
6504 /* On many CISC machines, accessing an object in a wider mode
6505 causes the high-order bits to become undefined. So they are
6506 not known to be zero. */
6507 if (GET_MODE_SIZE (GET_MODE (x))
6508 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
6509 nonzero |= (GET_MODE_MASK (GET_MODE (x))
6510 & ~ GET_MODE_MASK (GET_MODE (SUBREG_REG (x))));
6520 /* The nonzero bits are in two classes: any bits within MODE
6521 that aren't in GET_MODE (x) are always significant. The rest of the
6522 nonzero bits are those that are significant in the operand of
6523 the shift when shifted the appropriate number of bits. This
6524 shows that high-order bits are cleared by the right shift and
6525 low-order bits by left shifts. */
6526 if (GET_CODE (XEXP (x, 1)) == CONST_INT
6527 && INTVAL (XEXP (x, 1)) >= 0
6528 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT)
6530 enum machine_mode inner_mode = GET_MODE (x);
6531 int width = GET_MODE_BITSIZE (inner_mode);
6532 int count = INTVAL (XEXP (x, 1));
6533 unsigned HOST_WIDE_INT mode_mask = GET_MODE_MASK (inner_mode);
6534 unsigned HOST_WIDE_INT op_nonzero = nonzero_bits (XEXP (x, 0), mode);
6535 unsigned HOST_WIDE_INT inner = op_nonzero & mode_mask;
6536 unsigned HOST_WIDE_INT outer = 0;
6538 if (mode_width > width)
6539 outer = (op_nonzero & nonzero & ~ mode_mask);
6541 if (code == LSHIFTRT)
6543 else if (code == ASHIFTRT)
6547 /* If the sign bit may have been nonzero before the shift, we
6548 need to mark all the places it could have been copied to
6549 by the shift as possibly nonzero. */
6550 if (inner & ((HOST_WIDE_INT) 1 << (width - 1 - count)))
6551 inner |= (((HOST_WIDE_INT) 1 << count) - 1) << (width - count);
6553 else if (code == LSHIFT || code == ASHIFT)
6556 inner = ((inner << (count % width)
6557 | (inner >> (width - (count % width)))) & mode_mask);
6559 nonzero &= (outer | inner);
6564 /* This is at most the number of bits in the mode. */
6565 nonzero = ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width) + 1)) - 1;
6569 nonzero &= (nonzero_bits (XEXP (x, 1), mode)
6570 | nonzero_bits (XEXP (x, 2), mode));
6577 /* Return the number of bits at the high-order end of X that are known to
6578 be equal to the sign bit. This number will always be between 1 and
6579 the number of bits in the mode of X. MODE is the mode to be used
6580 if X is VOIDmode. */
6583 num_sign_bit_copies (x, mode)
6585 enum machine_mode mode;
6587 enum rtx_code code = GET_CODE (x);
6589 int num0, num1, result;
6590 unsigned HOST_WIDE_INT nonzero;
6593 /* If we weren't given a mode, use the mode of X. If the mode is still
6594 VOIDmode, we don't know anything. */
6596 if (mode == VOIDmode)
6597 mode = GET_MODE (x);
6599 if (mode == VOIDmode)
6602 bitwidth = GET_MODE_BITSIZE (mode);
6608 if (reg_last_set_value[REGNO (x)] != 0
6609 && reg_last_set_mode[REGNO (x)] == mode
6610 && (reg_n_sets[REGNO (x)] == 1
6611 || reg_last_set_label[REGNO (x)] == label_tick)
6612 && INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid)
6613 return reg_last_set_sign_bit_copies[REGNO (x)];
6615 tem = get_last_value (x);
6617 return num_sign_bit_copies (tem, mode);
6619 if (nonzero_sign_valid && reg_sign_bit_copies[REGNO (x)] != 0)
6620 return reg_sign_bit_copies[REGNO (x)];
6623 #ifdef BYTE_LOADS_SIGN_EXTEND
6625 /* Some RISC machines sign-extend all loads of smaller than a word. */
6626 return MAX (1, bitwidth - GET_MODE_BITSIZE (GET_MODE (x)) + 1);
6630 /* If the constant is negative, take its 1's complement and remask.
6631 Then see how many zero bits we have. */
6632 nonzero = INTVAL (x) & GET_MODE_MASK (mode);
6633 if (bitwidth <= HOST_BITS_PER_WIDE_INT
6634 && (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
6635 nonzero = (~ nonzero) & GET_MODE_MASK (mode);
6637 return (nonzero == 0 ? bitwidth : bitwidth - floor_log2 (nonzero) - 1);
6640 /* If this is a SUBREG for a promoted object that is sign-extended
6641 and we are looking at it in a wider mode, we know that at least the
6642 high-order bits are known to be sign bit copies. */
6644 if (SUBREG_PROMOTED_VAR_P (x) && ! SUBREG_PROMOTED_UNSIGNED_P (x))
6645 return MAX (bitwidth - GET_MODE_BITSIZE (GET_MODE (x)) + 1,
6646 num_sign_bit_copies (SUBREG_REG (x), mode));
6648 /* For a smaller object, just ignore the high bits. */
6649 if (bitwidth <= GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))))
6651 num0 = num_sign_bit_copies (SUBREG_REG (x), VOIDmode);
6652 return MAX (1, (num0
6653 - (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))
6657 #ifdef BYTE_LOADS_EXTEND
6658 /* For paradoxical SUBREGs, just look inside since, on machines with
6659 one of these defined, we assume that operations are actually
6660 performed on the full register. Note that we are passing MODE
6661 to the recursive call, so the number of sign bit copies will
6662 remain relative to that mode, not the inner mode. */
6664 if (GET_MODE_SIZE (GET_MODE (x))
6665 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
6666 return num_sign_bit_copies (SUBREG_REG (x), mode);
6672 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
6673 return MAX (1, bitwidth - INTVAL (XEXP (x, 1)));
6677 return (bitwidth - GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
6678 + num_sign_bit_copies (XEXP (x, 0), VOIDmode));
6681 /* For a smaller object, just ignore the high bits. */
6682 num0 = num_sign_bit_copies (XEXP (x, 0), VOIDmode);
6683 return MAX (1, (num0 - (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
6687 return num_sign_bit_copies (XEXP (x, 0), mode);
6689 case ROTATE: case ROTATERT:
6690 /* If we are rotating left by a number of bits less than the number
6691 of sign bit copies, we can just subtract that amount from the
6693 if (GET_CODE (XEXP (x, 1)) == CONST_INT
6694 && INTVAL (XEXP (x, 1)) >= 0 && INTVAL (XEXP (x, 1)) < bitwidth)
6696 num0 = num_sign_bit_copies (XEXP (x, 0), mode);
6697 return MAX (1, num0 - (code == ROTATE ? INTVAL (XEXP (x, 1))
6698 : bitwidth - INTVAL (XEXP (x, 1))));
6703 /* In general, this subtracts one sign bit copy. But if the value
6704 is known to be positive, the number of sign bit copies is the
6705 same as that of the input. Finally, if the input has just one bit
6706 that might be nonzero, all the bits are copies of the sign bit. */
6707 nonzero = nonzero_bits (XEXP (x, 0), mode);
6711 num0 = num_sign_bit_copies (XEXP (x, 0), mode);
6713 && bitwidth <= HOST_BITS_PER_WIDE_INT
6714 && (((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero))
6719 case IOR: case AND: case XOR:
6720 case SMIN: case SMAX: case UMIN: case UMAX:
6721 /* Logical operations will preserve the number of sign-bit copies.
6722 MIN and MAX operations always return one of the operands. */
6723 num0 = num_sign_bit_copies (XEXP (x, 0), mode);
6724 num1 = num_sign_bit_copies (XEXP (x, 1), mode);
6725 return MIN (num0, num1);
6727 case PLUS: case MINUS:
6728 /* For addition and subtraction, we can have a 1-bit carry. However,
6729 if we are subtracting 1 from a positive number, there will not
6730 be such a carry. Furthermore, if the positive number is known to
6731 be 0 or 1, we know the result is either -1 or 0. */
6733 if (code == PLUS && XEXP (x, 1) == constm1_rtx
6734 && bitwidth <= HOST_BITS_PER_WIDE_INT)
6736 nonzero = nonzero_bits (XEXP (x, 0), mode);
6737 if ((((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero) == 0)
6738 return (nonzero == 1 || nonzero == 0 ? bitwidth
6739 : bitwidth - floor_log2 (nonzero) - 1);
6742 num0 = num_sign_bit_copies (XEXP (x, 0), mode);
6743 num1 = num_sign_bit_copies (XEXP (x, 1), mode);
6744 return MAX (1, MIN (num0, num1) - 1);
6747 /* The number of bits of the product is the sum of the number of
6748 bits of both terms. However, unless one of the terms if known
6749 to be positive, we must allow for an additional bit since negating
6750 a negative number can remove one sign bit copy. */
6752 num0 = num_sign_bit_copies (XEXP (x, 0), mode);
6753 num1 = num_sign_bit_copies (XEXP (x, 1), mode);
6755 result = bitwidth - (bitwidth - num0) - (bitwidth - num1);
6757 && bitwidth <= HOST_BITS_PER_WIDE_INT
6758 && ((nonzero_bits (XEXP (x, 0), mode)
6759 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
6760 && (nonzero_bits (XEXP (x, 1), mode)
6761 & ((HOST_WIDE_INT) 1 << (bitwidth - 1)) != 0))
6764 return MAX (1, result);
6767 /* The result must be <= the first operand. */
6768 return num_sign_bit_copies (XEXP (x, 0), mode);
6771 /* The result must be <= the scond operand. */
6772 return num_sign_bit_copies (XEXP (x, 1), mode);
6775 /* Similar to unsigned division, except that we have to worry about
6776 the case where the divisor is negative, in which case we have
6778 result = num_sign_bit_copies (XEXP (x, 0), mode);
6780 && bitwidth <= HOST_BITS_PER_WIDE_INT
6781 && (nonzero_bits (XEXP (x, 1), mode)
6782 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
6788 result = num_sign_bit_copies (XEXP (x, 1), mode);
6790 && bitwidth <= HOST_BITS_PER_WIDE_INT
6791 && (nonzero_bits (XEXP (x, 1), mode)
6792 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
6798 /* Shifts by a constant add to the number of bits equal to the
6800 num0 = num_sign_bit_copies (XEXP (x, 0), mode);
6801 if (GET_CODE (XEXP (x, 1)) == CONST_INT
6802 && INTVAL (XEXP (x, 1)) > 0)
6803 num0 = MIN (bitwidth, num0 + INTVAL (XEXP (x, 1)));
6809 /* Left shifts destroy copies. */
6810 if (GET_CODE (XEXP (x, 1)) != CONST_INT
6811 || INTVAL (XEXP (x, 1)) < 0
6812 || INTVAL (XEXP (x, 1)) >= bitwidth)
6815 num0 = num_sign_bit_copies (XEXP (x, 0), mode);
6816 return MAX (1, num0 - INTVAL (XEXP (x, 1)));
6819 num0 = num_sign_bit_copies (XEXP (x, 1), mode);
6820 num1 = num_sign_bit_copies (XEXP (x, 2), mode);
6821 return MIN (num0, num1);
6823 #if STORE_FLAG_VALUE == -1
6824 case EQ: case NE: case GE: case GT: case LE: case LT:
6825 case GEU: case GTU: case LEU: case LTU:
6830 /* If we haven't been able to figure it out by one of the above rules,
6831 see if some of the high-order bits are known to be zero. If so,
6832 count those bits and return one less than that amount. If we can't
6833 safely compute the mask for this mode, always return BITWIDTH. */
6835 if (bitwidth > HOST_BITS_PER_WIDE_INT)
6838 nonzero = nonzero_bits (x, mode);
6839 return (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1))
6840 ? 1 : bitwidth - floor_log2 (nonzero) - 1);
6843 /* Return the number of "extended" bits there are in X, when interpreted
6844 as a quantity in MODE whose signedness is indicated by UNSIGNEDP. For
6845 unsigned quantities, this is the number of high-order zero bits.
6846 For signed quantities, this is the number of copies of the sign bit
6847 minus 1. In both case, this function returns the number of "spare"
6848 bits. For example, if two quantities for which this function returns
6849 at least 1 are added, the addition is known not to overflow.
6851 This function will always return 0 unless called during combine, which
6852 implies that it must be called from a define_split. */
6855 extended_count (x, mode, unsignedp)
6857 enum machine_mode mode;
6860 if (nonzero_sign_valid == 0)
6864 ? (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
6865 && (GET_MODE_BITSIZE (mode) - 1
6866 - floor_log2 (nonzero_bits (x, mode))))
6867 : num_sign_bit_copies (x, mode) - 1);
6870 /* This function is called from `simplify_shift_const' to merge two
6871 outer operations. Specifically, we have already found that we need
6872 to perform operation *POP0 with constant *PCONST0 at the outermost
6873 position. We would now like to also perform OP1 with constant CONST1
6874 (with *POP0 being done last).
6876 Return 1 if we can do the operation and update *POP0 and *PCONST0 with
6877 the resulting operation. *PCOMP_P is set to 1 if we would need to
6878 complement the innermost operand, otherwise it is unchanged.
6880 MODE is the mode in which the operation will be done. No bits outside
6881 the width of this mode matter. It is assumed that the width of this mode
6882 is smaller than or equal to HOST_BITS_PER_WIDE_INT.
6884 If *POP0 or OP1 are NIL, it means no operation is required. Only NEG, PLUS,
6885 IOR, XOR, and AND are supported. We may set *POP0 to SET if the proper
6886 result is simply *PCONST0.
6888 If the resulting operation cannot be expressed as one operation, we
6889 return 0 and do not change *POP0, *PCONST0, and *PCOMP_P. */
6892 merge_outer_ops (pop0, pconst0, op1, const1, mode, pcomp_p)
6893 enum rtx_code *pop0;
6894 HOST_WIDE_INT *pconst0;
6896 HOST_WIDE_INT const1;
6897 enum machine_mode mode;
6900 enum rtx_code op0 = *pop0;
6901 HOST_WIDE_INT const0 = *pconst0;
6903 const0 &= GET_MODE_MASK (mode);
6904 const1 &= GET_MODE_MASK (mode);
6906 /* If OP0 is an AND, clear unimportant bits in CONST1. */
6910 /* If OP0 or OP1 is NIL, this is easy. Similarly if they are the same or
6913 if (op1 == NIL || op0 == SET)
6916 else if (op0 == NIL)
6917 op0 = op1, const0 = const1;
6919 else if (op0 == op1)
6941 /* Otherwise, if either is a PLUS or NEG, we can't do anything. */
6942 else if (op0 == PLUS || op1 == PLUS || op0 == NEG || op1 == NEG)
6945 /* If the two constants aren't the same, we can't do anything. The
6946 remaining six cases can all be done. */
6947 else if (const0 != const1)
6955 /* (a & b) | b == b */
6957 else /* op1 == XOR */
6958 /* (a ^ b) | b == a | b */
6964 /* (a & b) ^ b == (~a) & b */
6965 op0 = AND, *pcomp_p = 1;
6966 else /* op1 == IOR */
6967 /* (a | b) ^ b == a & ~b */
6968 op0 = AND, *pconst0 = ~ const0;
6973 /* (a | b) & b == b */
6975 else /* op1 == XOR */
6976 /* (a ^ b) & b) == (~a) & b */
6981 /* Check for NO-OP cases. */
6982 const0 &= GET_MODE_MASK (mode);
6984 && (op0 == IOR || op0 == XOR || op0 == PLUS))
6986 else if (const0 == 0 && op0 == AND)
6988 else if (const0 == GET_MODE_MASK (mode) && op0 == AND)
6997 /* Simplify a shift of VAROP by COUNT bits. CODE says what kind of shift.
6998 The result of the shift is RESULT_MODE. X, if non-zero, is an expression
6999 that we started with.
7001 The shift is normally computed in the widest mode we find in VAROP, as
7002 long as it isn't a different number of words than RESULT_MODE. Exceptions
7003 are ASHIFTRT and ROTATE, which are always done in their original mode, */
7006 simplify_shift_const (x, code, result_mode, varop, count)
7009 enum machine_mode result_mode;
7013 enum rtx_code orig_code = code;
7014 int orig_count = count;
7015 enum machine_mode mode = result_mode;
7016 enum machine_mode shift_mode, tmode;
7018 = (GET_MODE_SIZE (mode) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD;
7019 /* We form (outer_op (code varop count) (outer_const)). */
7020 enum rtx_code outer_op = NIL;
7021 HOST_WIDE_INT outer_const;
7023 int complement_p = 0;
7026 /* If we were given an invalid count, don't do anything except exactly
7027 what was requested. */
7029 if (count < 0 || count > GET_MODE_BITSIZE (mode))
7034 return gen_rtx (code, mode, varop, GEN_INT (count));
7037 /* Unless one of the branches of the `if' in this loop does a `continue',
7038 we will `break' the loop after the `if'. */
7042 /* If we have an operand of (clobber (const_int 0)), just return that
7044 if (GET_CODE (varop) == CLOBBER)
7047 /* If we discovered we had to complement VAROP, leave. Making a NOT
7048 here would cause an infinite loop. */
7052 /* Convert ROTATETRT to ROTATE. */
7053 if (code == ROTATERT)
7054 code = ROTATE, count = GET_MODE_BITSIZE (result_mode) - count;
7056 /* Canonicalize LSHIFT to ASHIFT. */
7060 /* We need to determine what mode we will do the shift in. If the
7061 shift is a ASHIFTRT or ROTATE, we must always do it in the mode it
7062 was originally done in. Otherwise, we can do it in MODE, the widest
7063 mode encountered. */
7064 shift_mode = (code == ASHIFTRT || code == ROTATE ? result_mode : mode);
7066 /* Handle cases where the count is greater than the size of the mode
7067 minus 1. For ASHIFT, use the size minus one as the count (this can
7068 occur when simplifying (lshiftrt (ashiftrt ..))). For rotates,
7069 take the count modulo the size. For other shifts, the result is
7072 Since these shifts are being produced by the compiler by combining
7073 multiple operations, each of which are defined, we know what the
7074 result is supposed to be. */
7076 if (count > GET_MODE_BITSIZE (shift_mode) - 1)
7078 if (code == ASHIFTRT)
7079 count = GET_MODE_BITSIZE (shift_mode) - 1;
7080 else if (code == ROTATE || code == ROTATERT)
7081 count %= GET_MODE_BITSIZE (shift_mode);
7084 /* We can't simply return zero because there may be an
7092 /* Negative counts are invalid and should not have been made (a
7093 programmer-specified negative count should have been handled
7098 /* An arithmetic right shift of a quantity known to be -1 or 0
7100 if (code == ASHIFTRT
7101 && (num_sign_bit_copies (varop, shift_mode)
7102 == GET_MODE_BITSIZE (shift_mode)))
7108 /* If we are doing an arithmetic right shift and discarding all but
7109 the sign bit copies, this is equivalent to doing a shift by the
7110 bitsize minus one. Convert it into that shift because it will often
7111 allow other simplifications. */
7113 if (code == ASHIFTRT
7114 && (count + num_sign_bit_copies (varop, shift_mode)
7115 >= GET_MODE_BITSIZE (shift_mode)))
7116 count = GET_MODE_BITSIZE (shift_mode) - 1;
7118 /* We simplify the tests below and elsewhere by converting
7119 ASHIFTRT to LSHIFTRT if we know the sign bit is clear.
7120 `make_compound_operation' will convert it to a ASHIFTRT for
7121 those machines (such as Vax) that don't have a LSHIFTRT. */
7122 if (GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT
7124 && ((nonzero_bits (varop, shift_mode)
7125 & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (shift_mode) - 1)))
7129 switch (GET_CODE (varop))
7135 new = expand_compound_operation (varop);
7144 /* If we have (xshiftrt (mem ...) C) and C is MODE_WIDTH
7145 minus the width of a smaller mode, we can do this with a
7146 SIGN_EXTEND or ZERO_EXTEND from the narrower memory location. */
7147 if ((code == ASHIFTRT || code == LSHIFTRT)
7148 && ! mode_dependent_address_p (XEXP (varop, 0))
7149 && ! MEM_VOLATILE_P (varop)
7150 && (tmode = mode_for_size (GET_MODE_BITSIZE (mode) - count,
7151 MODE_INT, 1)) != BLKmode)
7153 #if BYTES_BIG_ENDIAN
7154 new = gen_rtx (MEM, tmode, XEXP (varop, 0));
7156 new = gen_rtx (MEM, tmode,
7157 plus_constant (XEXP (varop, 0),
7158 count / BITS_PER_UNIT));
7159 RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (varop);
7160 MEM_VOLATILE_P (new) = MEM_VOLATILE_P (varop);
7161 MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (varop);
7163 varop = gen_rtx_combine (code == ASHIFTRT ? SIGN_EXTEND
7164 : ZERO_EXTEND, mode, new);
7171 /* Similar to the case above, except that we can only do this if
7172 the resulting mode is the same as that of the underlying
7173 MEM and adjust the address depending on the *bits* endianness
7174 because of the way that bit-field extract insns are defined. */
7175 if ((code == ASHIFTRT || code == LSHIFTRT)
7176 && (tmode = mode_for_size (GET_MODE_BITSIZE (mode) - count,
7177 MODE_INT, 1)) != BLKmode
7178 && tmode == GET_MODE (XEXP (varop, 0)))
7181 new = XEXP (varop, 0);
7183 new = copy_rtx (XEXP (varop, 0));
7184 SUBST (XEXP (new, 0),
7185 plus_constant (XEXP (new, 0),
7186 count / BITS_PER_UNIT));
7189 varop = gen_rtx_combine (code == ASHIFTRT ? SIGN_EXTEND
7190 : ZERO_EXTEND, mode, new);
7197 /* If VAROP is a SUBREG, strip it as long as the inner operand has
7198 the same number of words as what we've seen so far. Then store
7199 the widest mode in MODE. */
7200 if (subreg_lowpart_p (varop)
7201 && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (varop)))
7202 > GET_MODE_SIZE (GET_MODE (varop)))
7203 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (varop)))
7204 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
7207 varop = SUBREG_REG (varop);
7208 if (GET_MODE_SIZE (GET_MODE (varop)) > GET_MODE_SIZE (mode))
7209 mode = GET_MODE (varop);
7215 /* Some machines use MULT instead of ASHIFT because MULT
7216 is cheaper. But it is still better on those machines to
7217 merge two shifts into one. */
7218 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
7219 && exact_log2 (INTVAL (XEXP (varop, 1))) >= 0)
7221 varop = gen_binary (ASHIFT, GET_MODE (varop), XEXP (varop, 0),
7222 GEN_INT (exact_log2 (INTVAL (XEXP (varop, 1)))));;
7228 /* Similar, for when divides are cheaper. */
7229 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
7230 && exact_log2 (INTVAL (XEXP (varop, 1))) >= 0)
7232 varop = gen_binary (LSHIFTRT, GET_MODE (varop), XEXP (varop, 0),
7233 GEN_INT (exact_log2 (INTVAL (XEXP (varop, 1)))));
7239 /* If we are extracting just the sign bit of an arithmetic right
7240 shift, that shift is not needed. */
7241 if (code == LSHIFTRT && count == GET_MODE_BITSIZE (result_mode) - 1)
7243 varop = XEXP (varop, 0);
7247 /* ... fall through ... */
7253 /* Here we have two nested shifts. The result is usually the
7254 AND of a new shift with a mask. We compute the result below. */
7255 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
7256 && INTVAL (XEXP (varop, 1)) >= 0
7257 && INTVAL (XEXP (varop, 1)) < GET_MODE_BITSIZE (GET_MODE (varop))
7258 && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
7259 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
7261 enum rtx_code first_code = GET_CODE (varop);
7262 int first_count = INTVAL (XEXP (varop, 1));
7263 unsigned HOST_WIDE_INT mask;
7267 if (first_code == LSHIFT)
7268 first_code = ASHIFT;
7270 /* We have one common special case. We can't do any merging if
7271 the inner code is an ASHIFTRT of a smaller mode. However, if
7272 we have (ashift:M1 (subreg:M1 (ashiftrt:M2 FOO C1) 0) C2)
7273 with C2 == GET_MODE_BITSIZE (M1) - GET_MODE_BITSIZE (M2),
7274 we can convert it to
7275 (ashiftrt:M1 (ashift:M1 (and:M1 (subreg:M1 FOO 0 C2) C3) C1).
7276 This simplifies certain SIGN_EXTEND operations. */
7277 if (code == ASHIFT && first_code == ASHIFTRT
7278 && (GET_MODE_BITSIZE (result_mode)
7279 - GET_MODE_BITSIZE (GET_MODE (varop))) == count)
7281 /* C3 has the low-order C1 bits zero. */
7283 mask = (GET_MODE_MASK (mode)
7284 & ~ (((HOST_WIDE_INT) 1 << first_count) - 1));
7286 varop = simplify_and_const_int (NULL_RTX, result_mode,
7287 XEXP (varop, 0), mask);
7288 varop = simplify_shift_const (NULL_RTX, ASHIFT, result_mode,
7290 count = first_count;
7295 /* If this was (ashiftrt (ashift foo C1) C2) and FOO has more
7296 than C1 high-order bits equal to the sign bit, we can convert
7297 this to either an ASHIFT or a ASHIFTRT depending on the
7300 We cannot do this if VAROP's mode is not SHIFT_MODE. */
7302 if (code == ASHIFTRT && first_code == ASHIFT
7303 && GET_MODE (varop) == shift_mode
7304 && (num_sign_bit_copies (XEXP (varop, 0), shift_mode)
7307 count -= first_count;
7309 count = - count, code = ASHIFT;
7310 varop = XEXP (varop, 0);
7314 /* There are some cases we can't do. If CODE is ASHIFTRT,
7315 we can only do this if FIRST_CODE is also ASHIFTRT.
7317 We can't do the case when CODE is ROTATE and FIRST_CODE is
7320 If the mode of this shift is not the mode of the outer shift,
7321 we can't do this if either shift is ASHIFTRT or ROTATE.
7323 Finally, we can't do any of these if the mode is too wide
7324 unless the codes are the same.
7326 Handle the case where the shift codes are the same
7329 if (code == first_code)
7331 if (GET_MODE (varop) != result_mode
7332 && (code == ASHIFTRT || code == ROTATE))
7335 count += first_count;
7336 varop = XEXP (varop, 0);
7340 if (code == ASHIFTRT
7341 || (code == ROTATE && first_code == ASHIFTRT)
7342 || GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT
7343 || (GET_MODE (varop) != result_mode
7344 && (first_code == ASHIFTRT || first_code == ROTATE
7345 || code == ROTATE)))
7348 /* To compute the mask to apply after the shift, shift the
7349 nonzero bits of the inner shift the same way the
7350 outer shift will. */
7352 mask_rtx = GEN_INT (nonzero_bits (varop, GET_MODE (varop)));
7355 = simplify_binary_operation (code, result_mode, mask_rtx,
7358 /* Give up if we can't compute an outer operation to use. */
7360 || GET_CODE (mask_rtx) != CONST_INT
7361 || ! merge_outer_ops (&outer_op, &outer_const, AND,
7363 result_mode, &complement_p))
7366 /* If the shifts are in the same direction, we add the
7367 counts. Otherwise, we subtract them. */
7368 if ((code == ASHIFTRT || code == LSHIFTRT)
7369 == (first_code == ASHIFTRT || first_code == LSHIFTRT))
7370 count += first_count;
7372 count -= first_count;
7374 /* If COUNT is positive, the new shift is usually CODE,
7375 except for the two exceptions below, in which case it is
7376 FIRST_CODE. If the count is negative, FIRST_CODE should
7379 && ((first_code == ROTATE && code == ASHIFT)
7380 || (first_code == ASHIFTRT && code == LSHIFTRT)))
7383 code = first_code, count = - count;
7385 varop = XEXP (varop, 0);
7389 /* If we have (A << B << C) for any shift, we can convert this to
7390 (A << C << B). This wins if A is a constant. Only try this if
7391 B is not a constant. */
7393 else if (GET_CODE (varop) == code
7394 && GET_CODE (XEXP (varop, 1)) != CONST_INT
7396 = simplify_binary_operation (code, mode,
7400 varop = gen_rtx_combine (code, mode, new, XEXP (varop, 1));
7407 /* Make this fit the case below. */
7408 varop = gen_rtx_combine (XOR, mode, XEXP (varop, 0),
7409 GEN_INT (GET_MODE_MASK (mode)));
7415 /* If we have (xshiftrt (ior (plus X (const_int -1)) X) C)
7416 with C the size of VAROP - 1 and the shift is logical if
7417 STORE_FLAG_VALUE is 1 and arithmetic if STORE_FLAG_VALUE is -1,
7418 we have an (le X 0) operation. If we have an arithmetic shift
7419 and STORE_FLAG_VALUE is 1 or we have a logical shift with
7420 STORE_FLAG_VALUE of -1, we have a (neg (le X 0)) operation. */
7422 if (GET_CODE (varop) == IOR && GET_CODE (XEXP (varop, 0)) == PLUS
7423 && XEXP (XEXP (varop, 0), 1) == constm1_rtx
7424 && (STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
7425 && (code == LSHIFTRT || code == ASHIFTRT)
7426 && count == GET_MODE_BITSIZE (GET_MODE (varop)) - 1
7427 && rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1)))
7430 varop = gen_rtx_combine (LE, GET_MODE (varop), XEXP (varop, 1),
7433 if (STORE_FLAG_VALUE == 1 ? code == ASHIFTRT : code == LSHIFTRT)
7434 varop = gen_rtx_combine (NEG, GET_MODE (varop), varop);
7439 /* If we have (shift (logical)), move the logical to the outside
7440 to allow it to possibly combine with another logical and the
7441 shift to combine with another shift. This also canonicalizes to
7442 what a ZERO_EXTRACT looks like. Also, some machines have
7443 (and (shift)) insns. */
7445 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
7446 && (new = simplify_binary_operation (code, result_mode,
7448 GEN_INT (count))) != 0
7449 && merge_outer_ops (&outer_op, &outer_const, GET_CODE (varop),
7450 INTVAL (new), result_mode, &complement_p))
7452 varop = XEXP (varop, 0);
7456 /* If we can't do that, try to simplify the shift in each arm of the
7457 logical expression, make a new logical expression, and apply
7458 the inverse distributive law. */
7460 rtx lhs = simplify_shift_const (NULL_RTX, code, result_mode,
7461 XEXP (varop, 0), count);
7462 rtx rhs = simplify_shift_const (NULL_RTX, code, result_mode,
7463 XEXP (varop, 1), count);
7465 varop = gen_binary (GET_CODE (varop), result_mode, lhs, rhs);
7466 varop = apply_distributive_law (varop);
7473 /* convert (lshift (eq FOO 0) C) to (xor FOO 1) if STORE_FLAG_VALUE
7474 says that the sign bit can be tested, FOO has mode MODE, C is
7475 GET_MODE_BITSIZE (MODE) - 1, and FOO has only the low-order bit
7478 && XEXP (varop, 1) == const0_rtx
7479 && GET_MODE (XEXP (varop, 0)) == result_mode
7480 && count == GET_MODE_BITSIZE (result_mode) - 1
7481 && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
7482 && ((STORE_FLAG_VALUE
7483 & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (result_mode) - 1))))
7484 && nonzero_bits (XEXP (varop, 0), result_mode) == 1
7485 && merge_outer_ops (&outer_op, &outer_const, XOR,
7486 (HOST_WIDE_INT) 1, result_mode,
7489 varop = XEXP (varop, 0);
7496 /* (lshiftrt (neg A) C) where A is either 0 or 1 and C is one less
7497 than the number of bits in the mode is equivalent to A. */
7498 if (code == LSHIFTRT && count == GET_MODE_BITSIZE (result_mode) - 1
7499 && nonzero_bits (XEXP (varop, 0), result_mode) == 1)
7501 varop = XEXP (varop, 0);
7506 /* NEG commutes with ASHIFT since it is multiplication. Move the
7507 NEG outside to allow shifts to combine. */
7509 && merge_outer_ops (&outer_op, &outer_const, NEG,
7510 (HOST_WIDE_INT) 0, result_mode,
7513 varop = XEXP (varop, 0);
7519 /* (lshiftrt (plus A -1) C) where A is either 0 or 1 and C
7520 is one less than the number of bits in the mode is
7521 equivalent to (xor A 1). */
7522 if (code == LSHIFTRT && count == GET_MODE_BITSIZE (result_mode) - 1
7523 && XEXP (varop, 1) == constm1_rtx
7524 && nonzero_bits (XEXP (varop, 0), result_mode) == 1
7525 && merge_outer_ops (&outer_op, &outer_const, XOR,
7526 (HOST_WIDE_INT) 1, result_mode,
7530 varop = XEXP (varop, 0);
7534 /* If we have (xshiftrt (plus FOO BAR) C), and the only bits
7535 that might be nonzero in BAR are those being shifted out and those
7536 bits are known zero in FOO, we can replace the PLUS with FOO.
7537 Similarly in the other operand order. This code occurs when
7538 we are computing the size of a variable-size array. */
7540 if ((code == ASHIFTRT || code == LSHIFTRT)
7541 && count < HOST_BITS_PER_WIDE_INT
7542 && nonzero_bits (XEXP (varop, 1), result_mode) >> count == 0
7543 && (nonzero_bits (XEXP (varop, 1), result_mode)
7544 & nonzero_bits (XEXP (varop, 0), result_mode)) == 0)
7546 varop = XEXP (varop, 0);
7549 else if ((code == ASHIFTRT || code == LSHIFTRT)
7550 && count < HOST_BITS_PER_WIDE_INT
7551 && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
7552 && 0 == (nonzero_bits (XEXP (varop, 0), result_mode)
7554 && 0 == (nonzero_bits (XEXP (varop, 0), result_mode)
7555 & nonzero_bits (XEXP (varop, 1),
7558 varop = XEXP (varop, 1);
7562 /* (ashift (plus foo C) N) is (plus (ashift foo N) C'). */
7564 && GET_CODE (XEXP (varop, 1)) == CONST_INT
7565 && (new = simplify_binary_operation (ASHIFT, result_mode,
7567 GEN_INT (count))) != 0
7568 && merge_outer_ops (&outer_op, &outer_const, PLUS,
7569 INTVAL (new), result_mode, &complement_p))
7571 varop = XEXP (varop, 0);
7577 /* If we have (xshiftrt (minus (ashiftrt X C)) X) C)
7578 with C the size of VAROP - 1 and the shift is logical if
7579 STORE_FLAG_VALUE is 1 and arithmetic if STORE_FLAG_VALUE is -1,
7580 we have a (gt X 0) operation. If the shift is arithmetic with
7581 STORE_FLAG_VALUE of 1 or logical with STORE_FLAG_VALUE == -1,
7582 we have a (neg (gt X 0)) operation. */
7584 if (GET_CODE (XEXP (varop, 0)) == ASHIFTRT
7585 && count == GET_MODE_BITSIZE (GET_MODE (varop)) - 1
7586 && (STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
7587 && (code == LSHIFTRT || code == ASHIFTRT)
7588 && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT
7589 && INTVAL (XEXP (XEXP (varop, 0), 1)) == count
7590 && rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1)))
7593 varop = gen_rtx_combine (GT, GET_MODE (varop), XEXP (varop, 1),
7596 if (STORE_FLAG_VALUE == 1 ? code == ASHIFTRT : code == LSHIFTRT)
7597 varop = gen_rtx_combine (NEG, GET_MODE (varop), varop);
7607 /* We need to determine what mode to do the shift in. If the shift is
7608 a ASHIFTRT or ROTATE, we must always do it in the mode it was originally
7609 done in. Otherwise, we can do it in MODE, the widest mode encountered.
7610 The code we care about is that of the shift that will actually be done,
7611 not the shift that was originally requested. */
7612 shift_mode = (code == ASHIFTRT || code == ROTATE ? result_mode : mode);
7614 /* We have now finished analyzing the shift. The result should be
7615 a shift of type CODE with SHIFT_MODE shifting VAROP COUNT places. If
7616 OUTER_OP is non-NIL, it is an operation that needs to be applied
7617 to the result of the shift. OUTER_CONST is the relevant constant,
7618 but we must turn off all bits turned off in the shift.
7620 If we were passed a value for X, see if we can use any pieces of
7621 it. If not, make new rtx. */
7623 if (x && GET_RTX_CLASS (GET_CODE (x)) == '2'
7624 && GET_CODE (XEXP (x, 1)) == CONST_INT
7625 && INTVAL (XEXP (x, 1)) == count)
7626 const_rtx = XEXP (x, 1);
7628 const_rtx = GEN_INT (count);
7630 if (x && GET_CODE (XEXP (x, 0)) == SUBREG
7631 && GET_MODE (XEXP (x, 0)) == shift_mode
7632 && SUBREG_REG (XEXP (x, 0)) == varop)
7633 varop = XEXP (x, 0);
7634 else if (GET_MODE (varop) != shift_mode)
7635 varop = gen_lowpart_for_combine (shift_mode, varop);
7637 /* If we can't make the SUBREG, try to return what we were given. */
7638 if (GET_CODE (varop) == CLOBBER)
7639 return x ? x : varop;
7641 new = simplify_binary_operation (code, shift_mode, varop, const_rtx);
7646 if (x == 0 || GET_CODE (x) != code || GET_MODE (x) != shift_mode)
7647 x = gen_rtx_combine (code, shift_mode, varop, const_rtx);
7649 SUBST (XEXP (x, 0), varop);
7650 SUBST (XEXP (x, 1), const_rtx);
7653 /* If we have an outer operation and we just made a shift, it is
7654 possible that we could have simplified the shift were it not
7655 for the outer operation. So try to do the simplification
7658 if (outer_op != NIL && GET_CODE (x) == code
7659 && GET_CODE (XEXP (x, 1)) == CONST_INT)
7660 x = simplify_shift_const (x, code, shift_mode, XEXP (x, 0),
7661 INTVAL (XEXP (x, 1)));
7663 /* If we were doing a LSHIFTRT in a wider mode than it was originally,
7664 turn off all the bits that the shift would have turned off. */
7665 if (orig_code == LSHIFTRT && result_mode != shift_mode)
7666 x = simplify_and_const_int (NULL_RTX, shift_mode, x,
7667 GET_MODE_MASK (result_mode) >> orig_count);
7669 /* Do the remainder of the processing in RESULT_MODE. */
7670 x = gen_lowpart_for_combine (result_mode, x);
7672 /* If COMPLEMENT_P is set, we have to complement X before doing the outer
7675 x = gen_unary (NOT, result_mode, x);
7677 if (outer_op != NIL)
7679 if (GET_MODE_BITSIZE (result_mode) < HOST_BITS_PER_WIDE_INT)
7680 outer_const &= GET_MODE_MASK (result_mode);
7682 if (outer_op == AND)
7683 x = simplify_and_const_int (NULL_RTX, result_mode, x, outer_const);
7684 else if (outer_op == SET)
7685 /* This means that we have determined that the result is
7686 equivalent to a constant. This should be rare. */
7687 x = GEN_INT (outer_const);
7688 else if (GET_RTX_CLASS (outer_op) == '1')
7689 x = gen_unary (outer_op, result_mode, x);
7691 x = gen_binary (outer_op, result_mode, x, GEN_INT (outer_const));
7697 /* Like recog, but we receive the address of a pointer to a new pattern.
7698 We try to match the rtx that the pointer points to.
7699 If that fails, we may try to modify or replace the pattern,
7700 storing the replacement into the same pointer object.
7702 Modifications include deletion or addition of CLOBBERs.
7704 PNOTES is a pointer to a location where any REG_UNUSED notes added for
7705 the CLOBBERs are placed.
7707 The value is the final insn code from the pattern ultimately matched,
7711 recog_for_combine (pnewpat, insn, pnotes)
7716 register rtx pat = *pnewpat;
7717 int insn_code_number;
7718 int num_clobbers_to_add = 0;
7722 /* Is the result of combination a valid instruction? */
7723 insn_code_number = recog (pat, insn, &num_clobbers_to_add);
7725 /* If it isn't, there is the possibility that we previously had an insn
7726 that clobbered some register as a side effect, but the combined
7727 insn doesn't need to do that. So try once more without the clobbers
7728 unless this represents an ASM insn. */
7730 if (insn_code_number < 0 && ! check_asm_operands (pat)
7731 && GET_CODE (pat) == PARALLEL)
7735 for (pos = 0, i = 0; i < XVECLEN (pat, 0); i++)
7736 if (GET_CODE (XVECEXP (pat, 0, i)) != CLOBBER)
7739 SUBST (XVECEXP (pat, 0, pos), XVECEXP (pat, 0, i));
7743 SUBST_INT (XVECLEN (pat, 0), pos);
7746 pat = XVECEXP (pat, 0, 0);
7748 insn_code_number = recog (pat, insn, &num_clobbers_to_add);
7751 /* If we had any clobbers to add, make a new pattern than contains
7752 them. Then check to make sure that all of them are dead. */
7753 if (num_clobbers_to_add)
7755 rtx newpat = gen_rtx (PARALLEL, VOIDmode,
7756 gen_rtvec (GET_CODE (pat) == PARALLEL
7757 ? XVECLEN (pat, 0) + num_clobbers_to_add
7758 : num_clobbers_to_add + 1));
7760 if (GET_CODE (pat) == PARALLEL)
7761 for (i = 0; i < XVECLEN (pat, 0); i++)
7762 XVECEXP (newpat, 0, i) = XVECEXP (pat, 0, i);
7764 XVECEXP (newpat, 0, 0) = pat;
7766 add_clobbers (newpat, insn_code_number);
7768 for (i = XVECLEN (newpat, 0) - num_clobbers_to_add;
7769 i < XVECLEN (newpat, 0); i++)
7771 if (GET_CODE (XEXP (XVECEXP (newpat, 0, i), 0)) == REG
7772 && ! reg_dead_at_p (XEXP (XVECEXP (newpat, 0, i), 0), insn))
7774 notes = gen_rtx (EXPR_LIST, REG_UNUSED,
7775 XEXP (XVECEXP (newpat, 0, i), 0), notes);
7783 return insn_code_number;
7786 /* Like gen_lowpart but for use by combine. In combine it is not possible
7787 to create any new pseudoregs. However, it is safe to create
7788 invalid memory addresses, because combine will try to recognize
7789 them and all they will do is make the combine attempt fail.
7791 If for some reason this cannot do its job, an rtx
7792 (clobber (const_int 0)) is returned.
7793 An insn containing that will not be recognized. */
7798 gen_lowpart_for_combine (mode, x)
7799 enum machine_mode mode;
7804 if (GET_MODE (x) == mode)
7807 /* We can only support MODE being wider than a word if X is a
7808 constant integer or has a mode the same size. */
7810 if (GET_MODE_SIZE (mode) > UNITS_PER_WORD
7811 && ! ((GET_MODE (x) == VOIDmode
7812 && (GET_CODE (x) == CONST_INT
7813 || GET_CODE (x) == CONST_DOUBLE))
7814 || GET_MODE_SIZE (GET_MODE (x)) == GET_MODE_SIZE (mode)))
7815 return gen_rtx (CLOBBER, GET_MODE (x), const0_rtx);
7817 /* X might be a paradoxical (subreg (mem)). In that case, gen_lowpart
7818 won't know what to do. So we will strip off the SUBREG here and
7819 process normally. */
7820 if (GET_CODE (x) == SUBREG && GET_CODE (SUBREG_REG (x)) == MEM)
7823 if (GET_MODE (x) == mode)
7827 result = gen_lowpart_common (mode, x);
7831 if (GET_CODE (x) == MEM)
7833 register int offset = 0;
7836 /* Refuse to work on a volatile memory ref or one with a mode-dependent
7838 if (MEM_VOLATILE_P (x) || mode_dependent_address_p (XEXP (x, 0)))
7839 return gen_rtx (CLOBBER, GET_MODE (x), const0_rtx);
7841 /* If we want to refer to something bigger than the original memref,
7842 generate a perverse subreg instead. That will force a reload
7843 of the original memref X. */
7844 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (mode))
7845 return gen_rtx (SUBREG, mode, x, 0);
7847 #if WORDS_BIG_ENDIAN
7848 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
7849 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
7851 #if BYTES_BIG_ENDIAN
7852 /* Adjust the address so that the address-after-the-data
7854 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
7855 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
7857 new = gen_rtx (MEM, mode, plus_constant (XEXP (x, 0), offset));
7858 RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (x);
7859 MEM_VOLATILE_P (new) = MEM_VOLATILE_P (x);
7860 MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (x);
7864 /* If X is a comparison operator, rewrite it in a new mode. This
7865 probably won't match, but may allow further simplifications. */
7866 else if (GET_RTX_CLASS (GET_CODE (x)) == '<')
7867 return gen_rtx_combine (GET_CODE (x), mode, XEXP (x, 0), XEXP (x, 1));
7869 /* If we couldn't simplify X any other way, just enclose it in a
7870 SUBREG. Normally, this SUBREG won't match, but some patterns may
7871 include an explicit SUBREG or we may simplify it further in combine. */
7876 if (WORDS_BIG_ENDIAN && GET_MODE_SIZE (GET_MODE (x)) > UNITS_PER_WORD)
7877 word = ((GET_MODE_SIZE (GET_MODE (x))
7878 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD))
7880 return gen_rtx (SUBREG, mode, x, word);
7884 /* Make an rtx expression. This is a subset of gen_rtx and only supports
7885 expressions of 1, 2, or 3 operands, each of which are rtx expressions.
7887 If the identical expression was previously in the insn (in the undobuf),
7888 it will be returned. Only if it is not found will a new expression
7893 gen_rtx_combine (va_alist)
7898 enum machine_mode mode;
7906 code = va_arg (p, enum rtx_code);
7907 mode = va_arg (p, enum machine_mode);
7908 n_args = GET_RTX_LENGTH (code);
7909 fmt = GET_RTX_FORMAT (code);
7911 if (n_args == 0 || n_args > 3)
7914 /* Get each arg and verify that it is supposed to be an expression. */
7915 for (j = 0; j < n_args; j++)
7920 args[j] = va_arg (p, rtx);
7923 /* See if this is in undobuf. Be sure we don't use objects that came
7924 from another insn; this could produce circular rtl structures. */
7926 for (i = previous_num_undos; i < undobuf.num_undo; i++)
7927 if (!undobuf.undo[i].is_int
7928 && GET_CODE (undobuf.undo[i].old_contents.rtx) == code
7929 && GET_MODE (undobuf.undo[i].old_contents.rtx) == mode)
7931 for (j = 0; j < n_args; j++)
7932 if (XEXP (undobuf.undo[i].old_contents.rtx, j) != args[j])
7936 return undobuf.undo[i].old_contents.rtx;
7939 /* Otherwise make a new rtx. We know we have 1, 2, or 3 args.
7940 Use rtx_alloc instead of gen_rtx because it's faster on RISC. */
7941 rt = rtx_alloc (code);
7942 PUT_MODE (rt, mode);
7943 XEXP (rt, 0) = args[0];
7946 XEXP (rt, 1) = args[1];
7948 XEXP (rt, 2) = args[2];
7953 /* These routines make binary and unary operations by first seeing if they
7954 fold; if not, a new expression is allocated. */
7957 gen_binary (code, mode, op0, op1)
7959 enum machine_mode mode;
7965 if (GET_RTX_CLASS (code) == 'c'
7966 && (GET_CODE (op0) == CONST_INT
7967 || (CONSTANT_P (op0) && GET_CODE (op1) != CONST_INT)))
7968 tem = op0, op0 = op1, op1 = tem;
7970 if (GET_RTX_CLASS (code) == '<')
7972 enum machine_mode op_mode = GET_MODE (op0);
7973 if (op_mode == VOIDmode)
7974 op_mode = GET_MODE (op1);
7975 result = simplify_relational_operation (code, op_mode, op0, op1);
7978 result = simplify_binary_operation (code, mode, op0, op1);
7983 /* Put complex operands first and constants second. */
7984 if (GET_RTX_CLASS (code) == 'c'
7985 && ((CONSTANT_P (op0) && GET_CODE (op1) != CONST_INT)
7986 || (GET_RTX_CLASS (GET_CODE (op0)) == 'o'
7987 && GET_RTX_CLASS (GET_CODE (op1)) != 'o')
7988 || (GET_CODE (op0) == SUBREG
7989 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (op0))) == 'o'
7990 && GET_RTX_CLASS (GET_CODE (op1)) != 'o')))
7991 return gen_rtx_combine (code, mode, op1, op0);
7993 return gen_rtx_combine (code, mode, op0, op1);
7997 gen_unary (code, mode, op0)
7999 enum machine_mode mode;
8002 rtx result = simplify_unary_operation (code, mode, op0, mode);
8007 return gen_rtx_combine (code, mode, op0);
8010 /* Simplify a comparison between *POP0 and *POP1 where CODE is the
8011 comparison code that will be tested.
8013 The result is a possibly different comparison code to use. *POP0 and
8014 *POP1 may be updated.
8016 It is possible that we might detect that a comparison is either always
8017 true or always false. However, we do not perform general constant
8018 folding in combine, so this knowledge isn't useful. Such tautologies
8019 should have been detected earlier. Hence we ignore all such cases. */
8021 static enum rtx_code
8022 simplify_comparison (code, pop0, pop1)
8031 enum machine_mode mode, tmode;
8033 /* Try a few ways of applying the same transformation to both operands. */
8036 /* If both operands are the same constant shift, see if we can ignore the
8037 shift. We can if the shift is a rotate or if the bits shifted out of
8038 this shift are known to be zero for both inputs and if the type of
8039 comparison is compatible with the shift. */
8040 if (GET_CODE (op0) == GET_CODE (op1)
8041 && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT
8042 && ((GET_CODE (op0) == ROTATE && (code == NE || code == EQ))
8043 || ((GET_CODE (op0) == LSHIFTRT
8044 || GET_CODE (op0) == ASHIFT || GET_CODE (op0) == LSHIFT)
8045 && (code != GT && code != LT && code != GE && code != LE))
8046 || (GET_CODE (op0) == ASHIFTRT
8047 && (code != GTU && code != LTU
8048 && code != GEU && code != GEU)))
8049 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8050 && INTVAL (XEXP (op0, 1)) >= 0
8051 && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT
8052 && XEXP (op0, 1) == XEXP (op1, 1))
8054 enum machine_mode mode = GET_MODE (op0);
8055 unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode);
8056 int shift_count = INTVAL (XEXP (op0, 1));
8058 if (GET_CODE (op0) == LSHIFTRT || GET_CODE (op0) == ASHIFTRT)
8059 mask &= (mask >> shift_count) << shift_count;
8060 else if (GET_CODE (op0) == ASHIFT || GET_CODE (op0) == LSHIFT)
8061 mask = (mask & (mask << shift_count)) >> shift_count;
8063 if ((nonzero_bits (XEXP (op0, 0), mode) & ~ mask) == 0
8064 && (nonzero_bits (XEXP (op1, 0), mode) & ~ mask) == 0)
8065 op0 = XEXP (op0, 0), op1 = XEXP (op1, 0);
8070 /* If both operands are AND's of a paradoxical SUBREG by constant, the
8071 SUBREGs are of the same mode, and, in both cases, the AND would
8072 be redundant if the comparison was done in the narrower mode,
8073 do the comparison in the narrower mode (e.g., we are AND'ing with 1
8074 and the operand's possibly nonzero bits are 0xffffff01; in that case
8075 if we only care about QImode, we don't need the AND). This case
8076 occurs if the output mode of an scc insn is not SImode and
8077 STORE_FLAG_VALUE == 1 (e.g., the 386). */
8079 else if (GET_CODE (op0) == AND && GET_CODE (op1) == AND
8080 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8081 && GET_CODE (XEXP (op1, 1)) == CONST_INT
8082 && GET_CODE (XEXP (op0, 0)) == SUBREG
8083 && GET_CODE (XEXP (op1, 0)) == SUBREG
8084 && (GET_MODE_SIZE (GET_MODE (XEXP (op0, 0)))
8085 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (op0, 0)))))
8086 && (GET_MODE (SUBREG_REG (XEXP (op0, 0)))
8087 == GET_MODE (SUBREG_REG (XEXP (op1, 0))))
8088 && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (XEXP (op0, 0))))
8089 <= HOST_BITS_PER_WIDE_INT)
8090 && (nonzero_bits (SUBREG_REG (XEXP (op0, 0)),
8091 GET_MODE (SUBREG_REG (XEXP (op0, 0))))
8092 & ~ INTVAL (XEXP (op0, 1))) == 0
8093 && (nonzero_bits (SUBREG_REG (XEXP (op1, 0)),
8094 GET_MODE (SUBREG_REG (XEXP (op1, 0))))
8095 & ~ INTVAL (XEXP (op1, 1))) == 0)
8097 op0 = SUBREG_REG (XEXP (op0, 0));
8098 op1 = SUBREG_REG (XEXP (op1, 0));
8100 /* the resulting comparison is always unsigned since we masked off
8101 the original sign bit. */
8102 code = unsigned_condition (code);
8108 /* If the first operand is a constant, swap the operands and adjust the
8109 comparison code appropriately. */
8110 if (CONSTANT_P (op0))
8112 tem = op0, op0 = op1, op1 = tem;
8113 code = swap_condition (code);
8116 /* We now enter a loop during which we will try to simplify the comparison.
8117 For the most part, we only are concerned with comparisons with zero,
8118 but some things may really be comparisons with zero but not start
8119 out looking that way. */
8121 while (GET_CODE (op1) == CONST_INT)
8123 enum machine_mode mode = GET_MODE (op0);
8124 int mode_width = GET_MODE_BITSIZE (mode);
8125 unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode);
8126 int equality_comparison_p;
8127 int sign_bit_comparison_p;
8128 int unsigned_comparison_p;
8129 HOST_WIDE_INT const_op;
8131 /* We only want to handle integral modes. This catches VOIDmode,
8132 CCmode, and the floating-point modes. An exception is that we
8133 can handle VOIDmode if OP0 is a COMPARE or a comparison
8136 if (GET_MODE_CLASS (mode) != MODE_INT
8137 && ! (mode == VOIDmode
8138 && (GET_CODE (op0) == COMPARE
8139 || GET_RTX_CLASS (GET_CODE (op0)) == '<')))
8142 /* Get the constant we are comparing against and turn off all bits
8143 not on in our mode. */
8144 const_op = INTVAL (op1);
8145 if (mode_width <= HOST_BITS_PER_WIDE_INT)
8148 /* If we are comparing against a constant power of two and the value
8149 being compared can only have that single bit nonzero (e.g., it was
8150 `and'ed with that bit), we can replace this with a comparison
8153 && (code == EQ || code == NE || code == GE || code == GEU
8154 || code == LT || code == LTU)
8155 && mode_width <= HOST_BITS_PER_WIDE_INT
8156 && exact_log2 (const_op) >= 0
8157 && nonzero_bits (op0, mode) == const_op)
8159 code = (code == EQ || code == GE || code == GEU ? NE : EQ);
8160 op1 = const0_rtx, const_op = 0;
8163 /* Similarly, if we are comparing a value known to be either -1 or
8164 0 with -1, change it to the opposite comparison against zero. */
8167 && (code == EQ || code == NE || code == GT || code == LE
8168 || code == GEU || code == LTU)
8169 && num_sign_bit_copies (op0, mode) == mode_width)
8171 code = (code == EQ || code == LE || code == GEU ? NE : EQ);
8172 op1 = const0_rtx, const_op = 0;
8175 /* Do some canonicalizations based on the comparison code. We prefer
8176 comparisons against zero and then prefer equality comparisons.
8177 If we can reduce the size of a constant, we will do that too. */
8182 /* < C is equivalent to <= (C - 1) */
8186 op1 = GEN_INT (const_op);
8188 /* ... fall through to LE case below. */
8194 /* <= C is equivalent to < (C + 1); we do this for C < 0 */
8198 op1 = GEN_INT (const_op);
8202 /* If we are doing a <= 0 comparison on a value known to have
8203 a zero sign bit, we can replace this with == 0. */
8204 else if (const_op == 0
8205 && mode_width <= HOST_BITS_PER_WIDE_INT
8206 && (nonzero_bits (op0, mode)
8207 & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0)
8212 /* >= C is equivalent to > (C - 1). */
8216 op1 = GEN_INT (const_op);
8218 /* ... fall through to GT below. */
8224 /* > C is equivalent to >= (C + 1); we do this for C < 0*/
8228 op1 = GEN_INT (const_op);
8232 /* If we are doing a > 0 comparison on a value known to have
8233 a zero sign bit, we can replace this with != 0. */
8234 else if (const_op == 0
8235 && mode_width <= HOST_BITS_PER_WIDE_INT
8236 && (nonzero_bits (op0, mode)
8237 & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0)
8242 /* < C is equivalent to <= (C - 1). */
8246 op1 = GEN_INT (const_op);
8248 /* ... fall through ... */
8251 /* (unsigned) < 0x80000000 is equivalent to >= 0. */
8252 else if (const_op == (HOST_WIDE_INT) 1 << (mode_width - 1))
8254 const_op = 0, op1 = const0_rtx;
8262 /* unsigned <= 0 is equivalent to == 0 */
8266 /* (unsigned) <= 0x7fffffff is equivalent to >= 0. */
8267 else if (const_op == ((HOST_WIDE_INT) 1 << (mode_width - 1)) - 1)
8269 const_op = 0, op1 = const0_rtx;
8275 /* >= C is equivalent to < (C - 1). */
8279 op1 = GEN_INT (const_op);
8281 /* ... fall through ... */
8284 /* (unsigned) >= 0x80000000 is equivalent to < 0. */
8285 else if (const_op == (HOST_WIDE_INT) 1 << (mode_width - 1))
8287 const_op = 0, op1 = const0_rtx;
8294 /* unsigned > 0 is equivalent to != 0 */
8298 /* (unsigned) > 0x7fffffff is equivalent to < 0. */
8299 else if (const_op == ((HOST_WIDE_INT) 1 << (mode_width - 1)) - 1)
8301 const_op = 0, op1 = const0_rtx;
8307 /* Compute some predicates to simplify code below. */
8309 equality_comparison_p = (code == EQ || code == NE);
8310 sign_bit_comparison_p = ((code == LT || code == GE) && const_op == 0);
8311 unsigned_comparison_p = (code == LTU || code == LEU || code == GTU
8314 /* Now try cases based on the opcode of OP0. If none of the cases
8315 does a "continue", we exit this loop immediately after the
8318 switch (GET_CODE (op0))
8321 /* If we are extracting a single bit from a variable position in
8322 a constant that has only a single bit set and are comparing it
8323 with zero, we can convert this into an equality comparison
8324 between the position and the location of the single bit. We can't
8325 do this if bit endian and we don't have an extzv since we then
8326 can't know what mode to use for the endianness adjustment. */
8328 #if ! BITS_BIG_ENDIAN || defined (HAVE_extzv)
8329 if (GET_CODE (XEXP (op0, 0)) == CONST_INT
8330 && XEXP (op0, 1) == const1_rtx
8331 && equality_comparison_p && const_op == 0
8332 && (i = exact_log2 (INTVAL (XEXP (op0, 0)))) >= 0)
8335 i = (GET_MODE_BITSIZE
8336 (insn_operand_mode[(int) CODE_FOR_extzv][1]) - 1 - i);
8339 op0 = XEXP (op0, 2);
8343 /* Result is nonzero iff shift count is equal to I. */
8344 code = reverse_condition (code);
8349 /* ... fall through ... */
8352 tem = expand_compound_operation (op0);
8361 /* If testing for equality, we can take the NOT of the constant. */
8362 if (equality_comparison_p
8363 && (tem = simplify_unary_operation (NOT, mode, op1, mode)) != 0)
8365 op0 = XEXP (op0, 0);
8370 /* If just looking at the sign bit, reverse the sense of the
8372 if (sign_bit_comparison_p)
8374 op0 = XEXP (op0, 0);
8375 code = (code == GE ? LT : GE);
8381 /* If testing for equality, we can take the NEG of the constant. */
8382 if (equality_comparison_p
8383 && (tem = simplify_unary_operation (NEG, mode, op1, mode)) != 0)
8385 op0 = XEXP (op0, 0);
8390 /* The remaining cases only apply to comparisons with zero. */
8394 /* When X is ABS or is known positive,
8395 (neg X) is < 0 if and only if X != 0. */
8397 if (sign_bit_comparison_p
8398 && (GET_CODE (XEXP (op0, 0)) == ABS
8399 || (mode_width <= HOST_BITS_PER_WIDE_INT
8400 && (nonzero_bits (XEXP (op0, 0), mode)
8401 & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0)))
8403 op0 = XEXP (op0, 0);
8404 code = (code == LT ? NE : EQ);
8408 /* If we have NEG of something whose two high-order bits are the
8409 same, we know that "(-a) < 0" is equivalent to "a > 0". */
8410 if (num_sign_bit_copies (op0, mode) >= 2)
8412 op0 = XEXP (op0, 0);
8413 code = swap_condition (code);
8419 /* If we are testing equality and our count is a constant, we
8420 can perform the inverse operation on our RHS. */
8421 if (equality_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT
8422 && (tem = simplify_binary_operation (ROTATERT, mode,
8423 op1, XEXP (op0, 1))) != 0)
8425 op0 = XEXP (op0, 0);
8430 /* If we are doing a < 0 or >= 0 comparison, it means we are testing
8431 a particular bit. Convert it to an AND of a constant of that
8432 bit. This will be converted into a ZERO_EXTRACT. */
8433 if (const_op == 0 && sign_bit_comparison_p
8434 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8435 && mode_width <= HOST_BITS_PER_WIDE_INT)
8437 op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0),
8440 - INTVAL (XEXP (op0, 1)))));
8441 code = (code == LT ? NE : EQ);
8445 /* ... fall through ... */
8448 /* ABS is ignorable inside an equality comparison with zero. */
8449 if (const_op == 0 && equality_comparison_p)
8451 op0 = XEXP (op0, 0);
8458 /* Can simplify (compare (zero/sign_extend FOO) CONST)
8459 to (compare FOO CONST) if CONST fits in FOO's mode and we
8460 are either testing inequality or have an unsigned comparison
8461 with ZERO_EXTEND or a signed comparison with SIGN_EXTEND. */
8462 if (! unsigned_comparison_p
8463 && (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0)))
8464 <= HOST_BITS_PER_WIDE_INT)
8465 && ((unsigned HOST_WIDE_INT) const_op
8466 < (((HOST_WIDE_INT) 1
8467 << (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0))) - 1)))))
8469 op0 = XEXP (op0, 0);
8475 /* Check for the case where we are comparing A - C1 with C2,
8476 both constants are smaller than 1/2 the maxium positive
8477 value in MODE, and the comparison is equality or unsigned.
8478 In that case, if A is either zero-extended to MODE or has
8479 sufficient sign bits so that the high-order bit in MODE
8480 is a copy of the sign in the inner mode, we can prove that it is
8481 safe to do the operation in the wider mode. This simplifies
8482 many range checks. */
8484 if (mode_width <= HOST_BITS_PER_WIDE_INT
8485 && subreg_lowpart_p (op0)
8486 && GET_CODE (SUBREG_REG (op0)) == PLUS
8487 && GET_CODE (XEXP (SUBREG_REG (op0), 1)) == CONST_INT
8488 && INTVAL (XEXP (SUBREG_REG (op0), 1)) < 0
8489 && (- INTVAL (XEXP (SUBREG_REG (op0), 1))
8490 < GET_MODE_MASK (mode) / 2)
8491 && (unsigned HOST_WIDE_INT) const_op < GET_MODE_MASK (mode) / 2
8492 && (0 == (nonzero_bits (XEXP (SUBREG_REG (op0), 0),
8493 GET_MODE (SUBREG_REG (op0)))
8494 & ~ GET_MODE_MASK (mode))
8495 || (num_sign_bit_copies (XEXP (SUBREG_REG (op0), 0),
8496 GET_MODE (SUBREG_REG (op0)))
8497 > (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0)))
8498 - GET_MODE_BITSIZE (mode)))))
8500 op0 = SUBREG_REG (op0);
8504 /* If the inner mode is narrower and we are extracting the low part,
8505 we can treat the SUBREG as if it were a ZERO_EXTEND. */
8506 if (subreg_lowpart_p (op0)
8507 && GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0))) < mode_width)
8508 /* Fall through */ ;
8512 /* ... fall through ... */
8515 if ((unsigned_comparison_p || equality_comparison_p)
8516 && (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0)))
8517 <= HOST_BITS_PER_WIDE_INT)
8518 && ((unsigned HOST_WIDE_INT) const_op
8519 < GET_MODE_MASK (GET_MODE (XEXP (op0, 0)))))
8521 op0 = XEXP (op0, 0);
8527 /* (eq (plus X A) B) -> (eq X (minus B A)). We can only do
8528 this for equality comparisons due to pathological cases involving
8530 if (equality_comparison_p
8531 && 0 != (tem = simplify_binary_operation (MINUS, mode,
8532 op1, XEXP (op0, 1))))
8534 op0 = XEXP (op0, 0);
8539 /* (plus (abs X) (const_int -1)) is < 0 if and only if X == 0. */
8540 if (const_op == 0 && XEXP (op0, 1) == constm1_rtx
8541 && GET_CODE (XEXP (op0, 0)) == ABS && sign_bit_comparison_p)
8543 op0 = XEXP (XEXP (op0, 0), 0);
8544 code = (code == LT ? EQ : NE);
8550 /* (eq (minus A B) C) -> (eq A (plus B C)) or
8551 (eq B (minus A C)), whichever simplifies. We can only do
8552 this for equality comparisons due to pathological cases involving
8554 if (equality_comparison_p
8555 && 0 != (tem = simplify_binary_operation (PLUS, mode,
8556 XEXP (op0, 1), op1)))
8558 op0 = XEXP (op0, 0);
8563 if (equality_comparison_p
8564 && 0 != (tem = simplify_binary_operation (MINUS, mode,
8565 XEXP (op0, 0), op1)))
8567 op0 = XEXP (op0, 1);
8572 /* The sign bit of (minus (ashiftrt X C) X), where C is the number
8573 of bits in X minus 1, is one iff X > 0. */
8574 if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 0)) == ASHIFTRT
8575 && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT
8576 && INTVAL (XEXP (XEXP (op0, 0), 1)) == mode_width - 1
8577 && rtx_equal_p (XEXP (XEXP (op0, 0), 0), XEXP (op0, 1)))
8579 op0 = XEXP (op0, 1);
8580 code = (code == GE ? LE : GT);
8586 /* (eq (xor A B) C) -> (eq A (xor B C)). This is a simplification
8587 if C is zero or B is a constant. */
8588 if (equality_comparison_p
8589 && 0 != (tem = simplify_binary_operation (XOR, mode,
8590 XEXP (op0, 1), op1)))
8592 op0 = XEXP (op0, 0);
8599 case LT: case LTU: case LE: case LEU:
8600 case GT: case GTU: case GE: case GEU:
8601 /* We can't do anything if OP0 is a condition code value, rather
8602 than an actual data value. */
8605 || XEXP (op0, 0) == cc0_rtx
8607 || GET_MODE_CLASS (GET_MODE (XEXP (op0, 0))) == MODE_CC)
8610 /* Get the two operands being compared. */
8611 if (GET_CODE (XEXP (op0, 0)) == COMPARE)
8612 tem = XEXP (XEXP (op0, 0), 0), tem1 = XEXP (XEXP (op0, 0), 1);
8614 tem = XEXP (op0, 0), tem1 = XEXP (op0, 1);
8616 /* Check for the cases where we simply want the result of the
8617 earlier test or the opposite of that result. */
8619 || (code == EQ && reversible_comparison_p (op0))
8620 || (GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT
8621 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
8622 && (STORE_FLAG_VALUE
8623 & (((HOST_WIDE_INT) 1
8624 << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1))))
8626 || (code == GE && reversible_comparison_p (op0)))))
8628 code = (code == LT || code == NE
8629 ? GET_CODE (op0) : reverse_condition (GET_CODE (op0)));
8630 op0 = tem, op1 = tem1;
8636 /* The sign bit of (ior (plus X (const_int -1)) X) is non-zero
8638 if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 0)) == PLUS
8639 && XEXP (XEXP (op0, 0), 1) == constm1_rtx
8640 && rtx_equal_p (XEXP (XEXP (op0, 0), 0), XEXP (op0, 1)))
8642 op0 = XEXP (op0, 1);
8643 code = (code == GE ? GT : LE);
8649 /* Convert (and (xshift 1 X) Y) to (and (lshiftrt Y X) 1). This
8650 will be converted to a ZERO_EXTRACT later. */
8651 if (const_op == 0 && equality_comparison_p
8652 && (GET_CODE (XEXP (op0, 0)) == ASHIFT
8653 || GET_CODE (XEXP (op0, 0)) == LSHIFT)
8654 && XEXP (XEXP (op0, 0), 0) == const1_rtx)
8656 op0 = simplify_and_const_int
8657 (op0, mode, gen_rtx_combine (LSHIFTRT, mode,
8659 XEXP (XEXP (op0, 0), 1)),
8664 /* If we are comparing (and (lshiftrt X C1) C2) for equality with
8665 zero and X is a comparison and C1 and C2 describe only bits set
8666 in STORE_FLAG_VALUE, we can compare with X. */
8667 if (const_op == 0 && equality_comparison_p
8668 && mode_width <= HOST_BITS_PER_WIDE_INT
8669 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8670 && GET_CODE (XEXP (op0, 0)) == LSHIFTRT
8671 && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT
8672 && INTVAL (XEXP (XEXP (op0, 0), 1)) >= 0
8673 && INTVAL (XEXP (XEXP (op0, 0), 1)) < HOST_BITS_PER_WIDE_INT)
8675 mask = ((INTVAL (XEXP (op0, 1)) & GET_MODE_MASK (mode))
8676 << INTVAL (XEXP (XEXP (op0, 0), 1)));
8677 if ((~ STORE_FLAG_VALUE & mask) == 0
8678 && (GET_RTX_CLASS (GET_CODE (XEXP (XEXP (op0, 0), 0))) == '<'
8679 || ((tem = get_last_value (XEXP (XEXP (op0, 0), 0))) != 0
8680 && GET_RTX_CLASS (GET_CODE (tem)) == '<')))
8682 op0 = XEXP (XEXP (op0, 0), 0);
8687 /* If we are doing an equality comparison of an AND of a bit equal
8688 to the sign bit, replace this with a LT or GE comparison of
8689 the underlying value. */
8690 if (equality_comparison_p
8692 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8693 && mode_width <= HOST_BITS_PER_WIDE_INT
8694 && ((INTVAL (XEXP (op0, 1)) & GET_MODE_MASK (mode))
8695 == (HOST_WIDE_INT) 1 << (mode_width - 1)))
8697 op0 = XEXP (op0, 0);
8698 code = (code == EQ ? GE : LT);
8702 /* If this AND operation is really a ZERO_EXTEND from a narrower
8703 mode, the constant fits within that mode, and this is either an
8704 equality or unsigned comparison, try to do this comparison in
8705 the narrower mode. */
8706 if ((equality_comparison_p || unsigned_comparison_p)
8707 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8708 && (i = exact_log2 ((INTVAL (XEXP (op0, 1))
8709 & GET_MODE_MASK (mode))
8711 && const_op >> i == 0
8712 && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode)
8714 op0 = gen_lowpart_for_combine (tmode, XEXP (op0, 0));
8721 /* If we have (compare (xshift FOO N) (const_int C)) and
8722 the high order N bits of FOO (N+1 if an inequality comparison)
8723 are known to be zero, we can do this by comparing FOO with C
8724 shifted right N bits so long as the low-order N bits of C are
8726 if (GET_CODE (XEXP (op0, 1)) == CONST_INT
8727 && INTVAL (XEXP (op0, 1)) >= 0
8728 && ((INTVAL (XEXP (op0, 1)) + ! equality_comparison_p)
8729 < HOST_BITS_PER_WIDE_INT)
8731 & ((HOST_WIDE_INT) 1 << INTVAL (XEXP (op0, 1))) - 1) == 0)
8732 && mode_width <= HOST_BITS_PER_WIDE_INT
8733 && (nonzero_bits (XEXP (op0, 0), mode)
8734 & ~ (mask >> (INTVAL (XEXP (op0, 1))
8735 + ! equality_comparison_p))) == 0)
8737 const_op >>= INTVAL (XEXP (op0, 1));
8738 op1 = GEN_INT (const_op);
8739 op0 = XEXP (op0, 0);
8743 /* If we are doing a sign bit comparison, it means we are testing
8744 a particular bit. Convert it to the appropriate AND. */
8745 if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT
8746 && mode_width <= HOST_BITS_PER_WIDE_INT)
8748 op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0),
8751 - INTVAL (XEXP (op0, 1)))));
8752 code = (code == LT ? NE : EQ);
8756 /* If this an equality comparison with zero and we are shifting
8757 the low bit to the sign bit, we can convert this to an AND of the
8759 if (const_op == 0 && equality_comparison_p
8760 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8761 && INTVAL (XEXP (op0, 1)) == mode_width - 1)
8763 op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0),
8770 /* If this is an equality comparison with zero, we can do this
8771 as a logical shift, which might be much simpler. */
8772 if (equality_comparison_p && const_op == 0
8773 && GET_CODE (XEXP (op0, 1)) == CONST_INT)
8775 op0 = simplify_shift_const (NULL_RTX, LSHIFTRT, mode,
8777 INTVAL (XEXP (op0, 1)));
8781 /* If OP0 is a sign extension and CODE is not an unsigned comparison,
8782 do the comparison in a narrower mode. */
8783 if (! unsigned_comparison_p
8784 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8785 && GET_CODE (XEXP (op0, 0)) == ASHIFT
8786 && XEXP (op0, 1) == XEXP (XEXP (op0, 0), 1)
8787 && (tmode = mode_for_size (mode_width - INTVAL (XEXP (op0, 1)),
8788 MODE_INT, 1)) != BLKmode
8789 && ((unsigned HOST_WIDE_INT) const_op <= GET_MODE_MASK (tmode)
8790 || ((unsigned HOST_WIDE_INT) - const_op
8791 <= GET_MODE_MASK (tmode))))
8793 op0 = gen_lowpart_for_combine (tmode, XEXP (XEXP (op0, 0), 0));
8797 /* ... fall through ... */
8799 /* If we have (compare (xshiftrt FOO N) (const_int C)) and
8800 the low order N bits of FOO are known to be zero, we can do this
8801 by comparing FOO with C shifted left N bits so long as no
8803 if (GET_CODE (XEXP (op0, 1)) == CONST_INT
8804 && INTVAL (XEXP (op0, 1)) >= 0
8805 && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT
8806 && mode_width <= HOST_BITS_PER_WIDE_INT
8807 && (nonzero_bits (XEXP (op0, 0), mode)
8808 & (((HOST_WIDE_INT) 1 << INTVAL (XEXP (op0, 1))) - 1)) == 0
8810 || (floor_log2 (const_op) + INTVAL (XEXP (op0, 1))
8813 const_op <<= INTVAL (XEXP (op0, 1));
8814 op1 = GEN_INT (const_op);
8815 op0 = XEXP (op0, 0);
8819 /* If we are using this shift to extract just the sign bit, we
8820 can replace this with an LT or GE comparison. */
8822 && (equality_comparison_p || sign_bit_comparison_p)
8823 && GET_CODE (XEXP (op0, 1)) == CONST_INT
8824 && INTVAL (XEXP (op0, 1)) == mode_width - 1)
8826 op0 = XEXP (op0, 0);
8827 code = (code == NE || code == GT ? LT : GE);
8836 /* Now make any compound operations involved in this comparison. Then,
8837 check for an outmost SUBREG on OP0 that isn't doing anything or is
8838 paradoxical. The latter case can only occur when it is known that the
8839 "extra" bits will be zero. Therefore, it is safe to remove the SUBREG.
8840 We can never remove a SUBREG for a non-equality comparison because the
8841 sign bit is in a different place in the underlying object. */
8843 op0 = make_compound_operation (op0, op1 == const0_rtx ? COMPARE : SET);
8844 op1 = make_compound_operation (op1, SET);
8846 if (GET_CODE (op0) == SUBREG && subreg_lowpart_p (op0)
8847 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
8848 && (code == NE || code == EQ)
8849 && ((GET_MODE_SIZE (GET_MODE (op0))
8850 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0))))))
8852 op0 = SUBREG_REG (op0);
8853 op1 = gen_lowpart_for_combine (GET_MODE (op0), op1);
8856 else if (GET_CODE (op0) == SUBREG && subreg_lowpart_p (op0)
8857 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
8858 && (code == NE || code == EQ)
8859 && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0)))
8860 <= HOST_BITS_PER_WIDE_INT)
8861 && (nonzero_bits (SUBREG_REG (op0), GET_MODE (SUBREG_REG (op0)))
8862 & ~ GET_MODE_MASK (GET_MODE (op0))) == 0
8863 && (tem = gen_lowpart_for_combine (GET_MODE (SUBREG_REG (op0)),
8865 (nonzero_bits (tem, GET_MODE (SUBREG_REG (op0)))
8866 & ~ GET_MODE_MASK (GET_MODE (op0))) == 0))
8867 op0 = SUBREG_REG (op0), op1 = tem;
8869 /* We now do the opposite procedure: Some machines don't have compare
8870 insns in all modes. If OP0's mode is an integer mode smaller than a
8871 word and we can't do a compare in that mode, see if there is a larger
8872 mode for which we can do the compare. There are a number of cases in
8873 which we can use the wider mode. */
8875 mode = GET_MODE (op0);
8876 if (mode != VOIDmode && GET_MODE_CLASS (mode) == MODE_INT
8877 && GET_MODE_SIZE (mode) < UNITS_PER_WORD
8878 && cmp_optab->handlers[(int) mode].insn_code == CODE_FOR_nothing)
8879 for (tmode = GET_MODE_WIDER_MODE (mode);
8881 && GET_MODE_BITSIZE (tmode) <= HOST_BITS_PER_WIDE_INT);
8882 tmode = GET_MODE_WIDER_MODE (tmode))
8883 if (cmp_optab->handlers[(int) tmode].insn_code != CODE_FOR_nothing)
8885 /* If the only nonzero bits in OP0 and OP1 are those in the
8886 narrower mode and this is an equality or unsigned comparison,
8887 we can use the wider mode. Similarly for sign-extended
8888 values and equality or signed comparisons. */
8889 if (((code == EQ || code == NE
8890 || code == GEU || code == GTU || code == LEU || code == LTU)
8891 && (nonzero_bits (op0, tmode) & ~ GET_MODE_MASK (mode)) == 0
8892 && (nonzero_bits (op1, tmode) & ~ GET_MODE_MASK (mode)) == 0)
8893 || ((code == EQ || code == NE
8894 || code == GE || code == GT || code == LE || code == LT)
8895 && (num_sign_bit_copies (op0, tmode)
8896 > GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))
8897 && (num_sign_bit_copies (op1, tmode)
8898 > GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))))
8900 op0 = gen_lowpart_for_combine (tmode, op0);
8901 op1 = gen_lowpart_for_combine (tmode, op1);
8905 /* If this is a test for negative, we can make an explicit
8906 test of the sign bit. */
8908 if (op1 == const0_rtx && (code == LT || code == GE)
8909 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
8911 op0 = gen_binary (AND, tmode,
8912 gen_lowpart_for_combine (tmode, op0),
8913 GEN_INT ((HOST_WIDE_INT) 1
8914 << (GET_MODE_BITSIZE (mode) - 1)));
8915 code = (code == LT) ? NE : EQ;
8926 /* Return 1 if we know that X, a comparison operation, is not operating
8927 on a floating-point value or is EQ or NE, meaning that we can safely
8931 reversible_comparison_p (x)
8934 if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
8935 || GET_CODE (x) == NE || GET_CODE (x) == EQ)
8938 switch (GET_MODE_CLASS (GET_MODE (XEXP (x, 0))))
8941 case MODE_PARTIAL_INT:
8942 case MODE_COMPLEX_INT:
8946 x = get_last_value (XEXP (x, 0));
8947 return (x && GET_CODE (x) == COMPARE
8948 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0))));
8954 /* Utility function for following routine. Called when X is part of a value
8955 being stored into reg_last_set_value. Sets reg_last_set_table_tick
8956 for each register mentioned. Similar to mention_regs in cse.c */
8959 update_table_tick (x)
8962 register enum rtx_code code = GET_CODE (x);
8963 register char *fmt = GET_RTX_FORMAT (code);
8968 int regno = REGNO (x);
8969 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
8970 ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);
8972 for (i = regno; i < endregno; i++)
8973 reg_last_set_table_tick[i] = label_tick;
8978 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
8979 /* Note that we can't have an "E" in values stored; see
8980 get_last_value_validate. */
8982 update_table_tick (XEXP (x, i));
8985 /* Record that REG is set to VALUE in insn INSN. If VALUE is zero, we
8986 are saying that the register is clobbered and we no longer know its
8987 value. If INSN is zero, don't update reg_last_set; this is only permitted
8988 with VALUE also zero and is used to invalidate the register. */
8991 record_value_for_reg (reg, insn, value)
8996 int regno = REGNO (reg);
8997 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
8998 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
9001 /* If VALUE contains REG and we have a previous value for REG, substitute
9002 the previous value. */
9003 if (value && insn && reg_overlap_mentioned_p (reg, value))
9007 /* Set things up so get_last_value is allowed to see anything set up to
9009 subst_low_cuid = INSN_CUID (insn);
9010 tem = get_last_value (reg);
9013 value = replace_rtx (copy_rtx (value), reg, tem);
9016 /* For each register modified, show we don't know its value, that
9017 its value has been updated, and that we don't know the location of
9018 the death of the register. */
9019 for (i = regno; i < endregno; i ++)
9022 reg_last_set[i] = insn;
9023 reg_last_set_value[i] = 0;
9024 reg_last_death[i] = 0;
9027 /* Mark registers that are being referenced in this value. */
9029 update_table_tick (value);
9031 /* Now update the status of each register being set.
9032 If someone is using this register in this block, set this register
9033 to invalid since we will get confused between the two lives in this
9034 basic block. This makes using this register always invalid. In cse, we
9035 scan the table to invalidate all entries using this register, but this
9036 is too much work for us. */
9038 for (i = regno; i < endregno; i++)
9040 reg_last_set_label[i] = label_tick;
9041 if (value && reg_last_set_table_tick[i] == label_tick)
9042 reg_last_set_invalid[i] = 1;
9044 reg_last_set_invalid[i] = 0;
9047 /* The value being assigned might refer to X (like in "x++;"). In that
9048 case, we must replace it with (clobber (const_int 0)) to prevent
9050 if (value && ! get_last_value_validate (&value,
9051 reg_last_set_label[regno], 0))
9053 value = copy_rtx (value);
9054 if (! get_last_value_validate (&value, reg_last_set_label[regno], 1))
9058 /* For the main register being modified, update the value, the mode, the
9059 nonzero bits, and the number of sign bit copies. */
9061 reg_last_set_value[regno] = value;
9065 subst_low_cuid = INSN_CUID (insn);
9066 reg_last_set_mode[regno] = GET_MODE (reg);
9067 reg_last_set_nonzero_bits[regno] = nonzero_bits (value, GET_MODE (reg));
9068 reg_last_set_sign_bit_copies[regno]
9069 = num_sign_bit_copies (value, GET_MODE (reg));
9073 /* Used for communication between the following two routines. */
9074 static rtx record_dead_insn;
9076 /* Called via note_stores from record_dead_and_set_regs to handle one
9077 SET or CLOBBER in an insn. */
9080 record_dead_and_set_regs_1 (dest, setter)
9083 if (GET_CODE (dest) == REG)
9085 /* If we are setting the whole register, we know its value. Otherwise
9086 show that we don't know the value. We can handle SUBREG in
9088 if (GET_CODE (setter) == SET && dest == SET_DEST (setter))
9089 record_value_for_reg (dest, record_dead_insn, SET_SRC (setter));
9090 else if (GET_CODE (setter) == SET
9091 && GET_CODE (SET_DEST (setter)) == SUBREG
9092 && SUBREG_REG (SET_DEST (setter)) == dest
9093 && subreg_lowpart_p (SET_DEST (setter)))
9094 record_value_for_reg (dest, record_dead_insn,
9095 gen_lowpart_for_combine (GET_MODE (dest),
9098 record_value_for_reg (dest, record_dead_insn, NULL_RTX);
9100 else if (GET_CODE (dest) == MEM
9101 /* Ignore pushes, they clobber nothing. */
9102 && ! push_operand (dest, GET_MODE (dest)))
9103 mem_last_set = INSN_CUID (record_dead_insn);
9106 /* Update the records of when each REG was most recently set or killed
9107 for the things done by INSN. This is the last thing done in processing
9108 INSN in the combiner loop.
9110 We update reg_last_set, reg_last_set_value, reg_last_death, and also the
9111 similar information mem_last_set (which insn most recently modified memory)
9112 and last_call_cuid (which insn was the most recent subroutine call). */
9115 record_dead_and_set_regs (insn)
9121 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
9123 if (REG_NOTE_KIND (link) == REG_DEAD
9124 && GET_CODE (XEXP (link, 0)) == REG)
9126 int regno = REGNO (XEXP (link, 0));
9128 = regno + (regno < FIRST_PSEUDO_REGISTER
9129 ? HARD_REGNO_NREGS (regno, GET_MODE (XEXP (link, 0)))
9132 for (i = regno; i < endregno; i++)
9133 reg_last_death[i] = insn;
9135 else if (REG_NOTE_KIND (link) == REG_INC)
9136 record_value_for_reg (XEXP (link, 0), insn, NULL_RTX);
9139 if (GET_CODE (insn) == CALL_INSN)
9141 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
9142 if (call_used_regs[i])
9144 reg_last_set_value[i] = 0;
9145 reg_last_death[i] = 0;
9148 last_call_cuid = mem_last_set = INSN_CUID (insn);
9151 record_dead_insn = insn;
9152 note_stores (PATTERN (insn), record_dead_and_set_regs_1);
9155 /* Utility routine for the following function. Verify that all the registers
9156 mentioned in *LOC are valid when *LOC was part of a value set when
9157 label_tick == TICK. Return 0 if some are not.
9159 If REPLACE is non-zero, replace the invalid reference with
9160 (clobber (const_int 0)) and return 1. This replacement is useful because
9161 we often can get useful information about the form of a value (e.g., if
9162 it was produced by a shift that always produces -1 or 0) even though
9163 we don't know exactly what registers it was produced from. */
9166 get_last_value_validate (loc, tick, replace)
9172 char *fmt = GET_RTX_FORMAT (GET_CODE (x));
9173 int len = GET_RTX_LENGTH (GET_CODE (x));
9176 if (GET_CODE (x) == REG)
9178 int regno = REGNO (x);
9179 int endregno = regno + (regno < FIRST_PSEUDO_REGISTER
9180 ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);
9183 for (j = regno; j < endregno; j++)
9184 if (reg_last_set_invalid[j]
9185 /* If this is a pseudo-register that was only set once, it is
9187 || (! (regno >= FIRST_PSEUDO_REGISTER && reg_n_sets[regno] == 1)
9188 && reg_last_set_label[j] > tick))
9191 *loc = gen_rtx (CLOBBER, GET_MODE (x), const0_rtx);
9198 for (i = 0; i < len; i++)
9200 && get_last_value_validate (&XEXP (x, i), tick, replace) == 0)
9201 /* Don't bother with these. They shouldn't occur anyway. */
9205 /* If we haven't found a reason for it to be invalid, it is valid. */
9209 /* Get the last value assigned to X, if known. Some registers
9210 in the value may be replaced with (clobber (const_int 0)) if their value
9211 is known longer known reliably. */
9220 /* If this is a non-paradoxical SUBREG, get the value of its operand and
9221 then convert it to the desired mode. If this is a paradoxical SUBREG,
9222 we cannot predict what values the "extra" bits might have. */
9223 if (GET_CODE (x) == SUBREG
9224 && subreg_lowpart_p (x)
9225 && (GET_MODE_SIZE (GET_MODE (x))
9226 <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
9227 && (value = get_last_value (SUBREG_REG (x))) != 0)
9228 return gen_lowpart_for_combine (GET_MODE (x), value);
9230 if (GET_CODE (x) != REG)
9234 value = reg_last_set_value[regno];
9236 /* If we don't have a value or if it isn't for this basic block, return 0. */
9239 || (reg_n_sets[regno] != 1
9240 && reg_last_set_label[regno] != label_tick))
9243 /* If the value was set in a later insn that the ones we are processing,
9244 we can't use it even if the register was only set once, but make a quick
9245 check to see if the previous insn set it to something. This is commonly
9246 the case when the same pseudo is used by repeated insns. */
9248 if (INSN_CUID (reg_last_set[regno]) >= subst_low_cuid)
9252 for (insn = prev_nonnote_insn (subst_insn);
9253 insn && INSN_CUID (insn) >= subst_low_cuid;
9254 insn = prev_nonnote_insn (insn))
9258 && (set = single_set (insn)) != 0
9259 && rtx_equal_p (SET_DEST (set), x))
9261 value = SET_SRC (set);
9263 /* Make sure that VALUE doesn't reference X. Replace any
9264 expliit references with a CLOBBER. If there are any remaining
9265 references (rare), don't use the value. */
9267 if (reg_mentioned_p (x, value))
9268 value = replace_rtx (copy_rtx (value), x,
9269 gen_rtx (CLOBBER, GET_MODE (x), const0_rtx));
9271 if (reg_overlap_mentioned_p (x, value))
9278 /* If the value has all its registers valid, return it. */
9279 if (get_last_value_validate (&value, reg_last_set_label[regno], 0))
9282 /* Otherwise, make a copy and replace any invalid register with
9283 (clobber (const_int 0)). If that fails for some reason, return 0. */
9285 value = copy_rtx (value);
9286 if (get_last_value_validate (&value, reg_last_set_label[regno], 1))
9292 /* Return nonzero if expression X refers to a REG or to memory
9293 that is set in an instruction more recent than FROM_CUID. */
9296 use_crosses_set_p (x, from_cuid)
9302 register enum rtx_code code = GET_CODE (x);
9306 register int regno = REGNO (x);
9307 #ifdef PUSH_ROUNDING
9308 /* Don't allow uses of the stack pointer to be moved,
9309 because we don't know whether the move crosses a push insn. */
9310 if (regno == STACK_POINTER_REGNUM)
9313 return (reg_last_set[regno]
9314 && INSN_CUID (reg_last_set[regno]) > from_cuid);
9317 if (code == MEM && mem_last_set > from_cuid)
9320 fmt = GET_RTX_FORMAT (code);
9322 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
9327 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
9328 if (use_crosses_set_p (XVECEXP (x, i, j), from_cuid))
9331 else if (fmt[i] == 'e'
9332 && use_crosses_set_p (XEXP (x, i), from_cuid))
9338 /* Define three variables used for communication between the following
9341 static int reg_dead_regno, reg_dead_endregno;
9342 static int reg_dead_flag;
9344 /* Function called via note_stores from reg_dead_at_p.
9346 If DEST is within [reg_dead_rengno, reg_dead_endregno), set
9347 reg_dead_flag to 1 if X is a CLOBBER and to -1 it is a SET. */
9350 reg_dead_at_p_1 (dest, x)
9354 int regno, endregno;
9356 if (GET_CODE (dest) != REG)
9359 regno = REGNO (dest);
9360 endregno = regno + (regno < FIRST_PSEUDO_REGISTER
9361 ? HARD_REGNO_NREGS (regno, GET_MODE (dest)) : 1);
9363 if (reg_dead_endregno > regno && reg_dead_regno < endregno)
9364 reg_dead_flag = (GET_CODE (x) == CLOBBER) ? 1 : -1;
9367 /* Return non-zero if REG is known to be dead at INSN.
9369 We scan backwards from INSN. If we hit a REG_DEAD note or a CLOBBER
9370 referencing REG, it is dead. If we hit a SET referencing REG, it is
9371 live. Otherwise, see if it is live or dead at the start of the basic
9375 reg_dead_at_p (reg, insn)
9381 /* Set variables for reg_dead_at_p_1. */
9382 reg_dead_regno = REGNO (reg);
9383 reg_dead_endregno = reg_dead_regno + (reg_dead_regno < FIRST_PSEUDO_REGISTER
9384 ? HARD_REGNO_NREGS (reg_dead_regno,
9390 /* Scan backwards until we find a REG_DEAD note, SET, CLOBBER, label, or
9391 beginning of function. */
9392 for (; insn && GET_CODE (insn) != CODE_LABEL;
9393 insn = prev_nonnote_insn (insn))
9395 note_stores (PATTERN (insn), reg_dead_at_p_1);
9397 return reg_dead_flag == 1 ? 1 : 0;
9399 if (find_regno_note (insn, REG_DEAD, reg_dead_regno))
9403 /* Get the basic block number that we were in. */
9408 for (block = 0; block < n_basic_blocks; block++)
9409 if (insn == basic_block_head[block])
9412 if (block == n_basic_blocks)
9416 for (i = reg_dead_regno; i < reg_dead_endregno; i++)
9417 if (basic_block_live_at_start[block][i / REGSET_ELT_BITS]
9418 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
9424 /* Remove register number REGNO from the dead registers list of INSN.
9426 Return the note used to record the death, if there was one. */
9429 remove_death (regno, insn)
9433 register rtx note = find_regno_note (insn, REG_DEAD, regno);
9437 reg_n_deaths[regno]--;
9438 remove_note (insn, note);
9444 /* For each register (hardware or pseudo) used within expression X, if its
9445 death is in an instruction with cuid between FROM_CUID (inclusive) and
9446 TO_INSN (exclusive), put a REG_DEAD note for that register in the
9447 list headed by PNOTES.
9449 This is done when X is being merged by combination into TO_INSN. These
9450 notes will then be distributed as needed. */
9453 move_deaths (x, from_cuid, to_insn, pnotes)
9460 register int len, i;
9461 register enum rtx_code code = GET_CODE (x);
9465 register int regno = REGNO (x);
9466 register rtx where_dead = reg_last_death[regno];
9468 if (where_dead && INSN_CUID (where_dead) >= from_cuid
9469 && INSN_CUID (where_dead) < INSN_CUID (to_insn))
9471 rtx note = remove_death (regno, where_dead);
9473 /* It is possible for the call above to return 0. This can occur
9474 when reg_last_death points to I2 or I1 that we combined with.
9475 In that case make a new note.
9477 We must also check for the case where X is a hard register
9478 and NOTE is a death note for a range of hard registers
9479 including X. In that case, we must put REG_DEAD notes for
9480 the remaining registers in place of NOTE. */
9482 if (note != 0 && regno < FIRST_PSEUDO_REGISTER
9483 && (GET_MODE_SIZE (GET_MODE (XEXP (note, 0)))
9484 != GET_MODE_SIZE (GET_MODE (x))))
9486 int deadregno = REGNO (XEXP (note, 0));
9488 = (deadregno + HARD_REGNO_NREGS (deadregno,
9489 GET_MODE (XEXP (note, 0))));
9490 int ourend = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
9493 for (i = deadregno; i < deadend; i++)
9494 if (i < regno || i >= ourend)
9495 REG_NOTES (where_dead)
9496 = gen_rtx (EXPR_LIST, REG_DEAD,
9497 gen_rtx (REG, word_mode, i),
9498 REG_NOTES (where_dead));
9501 if (note != 0 && GET_MODE (XEXP (note, 0)) == GET_MODE (x))
9503 XEXP (note, 1) = *pnotes;
9507 *pnotes = gen_rtx (EXPR_LIST, REG_DEAD, x, *pnotes);
9509 reg_n_deaths[regno]++;
9515 else if (GET_CODE (x) == SET)
9517 rtx dest = SET_DEST (x);
9519 move_deaths (SET_SRC (x), from_cuid, to_insn, pnotes);
9521 /* In the case of a ZERO_EXTRACT, a STRICT_LOW_PART, or a SUBREG
9522 that accesses one word of a multi-word item, some
9523 piece of everything register in the expression is used by
9524 this insn, so remove any old death. */
9526 if (GET_CODE (dest) == ZERO_EXTRACT
9527 || GET_CODE (dest) == STRICT_LOW_PART
9528 || (GET_CODE (dest) == SUBREG
9529 && (((GET_MODE_SIZE (GET_MODE (dest))
9530 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
9531 == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest)))
9532 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))))
9534 move_deaths (dest, from_cuid, to_insn, pnotes);
9538 /* If this is some other SUBREG, we know it replaces the entire
9539 value, so use that as the destination. */
9540 if (GET_CODE (dest) == SUBREG)
9541 dest = SUBREG_REG (dest);
9543 /* If this is a MEM, adjust deaths of anything used in the address.
9544 For a REG (the only other possibility), the entire value is
9545 being replaced so the old value is not used in this insn. */
9547 if (GET_CODE (dest) == MEM)
9548 move_deaths (XEXP (dest, 0), from_cuid, to_insn, pnotes);
9552 else if (GET_CODE (x) == CLOBBER)
9555 len = GET_RTX_LENGTH (code);
9556 fmt = GET_RTX_FORMAT (code);
9558 for (i = 0; i < len; i++)
9563 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
9564 move_deaths (XVECEXP (x, i, j), from_cuid, to_insn, pnotes);
9566 else if (fmt[i] == 'e')
9567 move_deaths (XEXP (x, i), from_cuid, to_insn, pnotes);
9571 /* Return 1 if X is the target of a bit-field assignment in BODY, the
9572 pattern of an insn. X must be a REG. */
9575 reg_bitfield_target_p (x, body)
9581 if (GET_CODE (body) == SET)
9583 rtx dest = SET_DEST (body);
9585 int regno, tregno, endregno, endtregno;
9587 if (GET_CODE (dest) == ZERO_EXTRACT)
9588 target = XEXP (dest, 0);
9589 else if (GET_CODE (dest) == STRICT_LOW_PART)
9590 target = SUBREG_REG (XEXP (dest, 0));
9594 if (GET_CODE (target) == SUBREG)
9595 target = SUBREG_REG (target);
9597 if (GET_CODE (target) != REG)
9600 tregno = REGNO (target), regno = REGNO (x);
9601 if (tregno >= FIRST_PSEUDO_REGISTER || regno >= FIRST_PSEUDO_REGISTER)
9604 endtregno = tregno + HARD_REGNO_NREGS (tregno, GET_MODE (target));
9605 endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
9607 return endregno > tregno && regno < endtregno;
9610 else if (GET_CODE (body) == PARALLEL)
9611 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
9612 if (reg_bitfield_target_p (x, XVECEXP (body, 0, i)))
9618 /* Given a chain of REG_NOTES originally from FROM_INSN, try to place them
9619 as appropriate. I3 and I2 are the insns resulting from the combination
9620 insns including FROM (I2 may be zero).
9622 ELIM_I2 and ELIM_I1 are either zero or registers that we know will
9623 not need REG_DEAD notes because they are being substituted for. This
9624 saves searching in the most common cases.
9626 Each note in the list is either ignored or placed on some insns, depending
9627 on the type of note. */
9630 distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
9634 rtx elim_i2, elim_i1;
9636 rtx note, next_note;
9639 for (note = notes; note; note = next_note)
9641 rtx place = 0, place2 = 0;
9643 /* If this NOTE references a pseudo register, ensure it references
9644 the latest copy of that register. */
9645 if (XEXP (note, 0) && GET_CODE (XEXP (note, 0)) == REG
9646 && REGNO (XEXP (note, 0)) >= FIRST_PSEUDO_REGISTER)
9647 XEXP (note, 0) = regno_reg_rtx[REGNO (XEXP (note, 0))];
9649 next_note = XEXP (note, 1);
9650 switch (REG_NOTE_KIND (note))
9653 /* If this register is set or clobbered in I3, put the note there
9654 unless there is one already. */
9655 if (reg_set_p (XEXP (note, 0), PATTERN (i3)))
9657 if (! (GET_CODE (XEXP (note, 0)) == REG
9658 ? find_regno_note (i3, REG_UNUSED, REGNO (XEXP (note, 0)))
9659 : find_reg_note (i3, REG_UNUSED, XEXP (note, 0))))
9662 /* Otherwise, if this register is used by I3, then this register
9663 now dies here, so we must put a REG_DEAD note here unless there
9665 else if (reg_referenced_p (XEXP (note, 0), PATTERN (i3))
9666 && ! (GET_CODE (XEXP (note, 0)) == REG
9667 ? find_regno_note (i3, REG_DEAD, REGNO (XEXP (note, 0)))
9668 : find_reg_note (i3, REG_DEAD, XEXP (note, 0))))
9670 PUT_REG_NOTE_KIND (note, REG_DEAD);
9678 /* These notes say something about results of an insn. We can
9679 only support them if they used to be on I3 in which case they
9680 remain on I3. Otherwise they are ignored.
9682 If the note refers to an expression that is not a constant, we
9683 must also ignore the note since we cannot tell whether the
9684 equivalence is still true. It might be possible to do
9685 slightly better than this (we only have a problem if I2DEST
9686 or I1DEST is present in the expression), but it doesn't
9687 seem worth the trouble. */
9690 && (XEXP (note, 0) == 0 || CONSTANT_P (XEXP (note, 0))))
9695 case REG_NO_CONFLICT:
9697 /* These notes say something about how a register is used. They must
9698 be present on any use of the register in I2 or I3. */
9699 if (reg_mentioned_p (XEXP (note, 0), PATTERN (i3)))
9702 if (i2 && reg_mentioned_p (XEXP (note, 0), PATTERN (i2)))
9712 /* It is too much trouble to try to see if this note is still
9713 correct in all situations. It is better to simply delete it. */
9717 /* If the insn previously containing this note still exists,
9718 put it back where it was. Otherwise move it to the previous
9719 insn. Adjust the corresponding REG_LIBCALL note. */
9720 if (GET_CODE (from_insn) != NOTE)
9724 tem = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
9725 place = prev_real_insn (from_insn);
9727 XEXP (tem, 0) = place;
9732 /* This is handled similarly to REG_RETVAL. */
9733 if (GET_CODE (from_insn) != NOTE)
9737 tem = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
9738 place = next_real_insn (from_insn);
9740 XEXP (tem, 0) = place;
9745 /* If the register is used as an input in I3, it dies there.
9746 Similarly for I2, if it is non-zero and adjacent to I3.
9748 If the register is not used as an input in either I3 or I2
9749 and it is not one of the registers we were supposed to eliminate,
9750 there are two possibilities. We might have a non-adjacent I2
9751 or we might have somehow eliminated an additional register
9752 from a computation. For example, we might have had A & B where
9753 we discover that B will always be zero. In this case we will
9754 eliminate the reference to A.
9756 In both cases, we must search to see if we can find a previous
9757 use of A and put the death note there. */
9759 if (reg_referenced_p (XEXP (note, 0), PATTERN (i3)))
9761 else if (i2 != 0 && next_nonnote_insn (i2) == i3
9762 && reg_referenced_p (XEXP (note, 0), PATTERN (i2)))
9765 if (XEXP (note, 0) == elim_i2 || XEXP (note, 0) == elim_i1)
9768 /* If the register is used in both I2 and I3 and it dies in I3,
9769 we might have added another reference to it. If reg_n_refs
9770 was 2, bump it to 3. This has to be correct since the
9771 register must have been set somewhere. The reason this is
9772 done is because local-alloc.c treats 2 references as a
9775 if (place == i3 && i2 != 0 && GET_CODE (XEXP (note, 0)) == REG
9776 && reg_n_refs[REGNO (XEXP (note, 0))]== 2
9777 && reg_referenced_p (XEXP (note, 0), PATTERN (i2)))
9778 reg_n_refs[REGNO (XEXP (note, 0))] = 3;
9781 for (tem = prev_nonnote_insn (i3);
9782 tem && (GET_CODE (tem) == INSN
9783 || GET_CODE (tem) == CALL_INSN);
9784 tem = prev_nonnote_insn (tem))
9786 /* If the register is being set at TEM, see if that is all
9787 TEM is doing. If so, delete TEM. Otherwise, make this
9788 into a REG_UNUSED note instead. */
9789 if (reg_set_p (XEXP (note, 0), PATTERN (tem)))
9791 rtx set = single_set (tem);
9793 /* Verify that it was the set, and not a clobber that
9794 modified the register. */
9796 if (set != 0 && ! side_effects_p (SET_SRC (set))
9797 && rtx_equal_p (XEXP (note, 0), SET_DEST (set)))
9799 /* Move the notes and links of TEM elsewhere.
9800 This might delete other dead insns recursively.
9801 First set the pattern to something that won't use
9804 PATTERN (tem) = pc_rtx;
9806 distribute_notes (REG_NOTES (tem), tem, tem,
9807 NULL_RTX, NULL_RTX, NULL_RTX);
9808 distribute_links (LOG_LINKS (tem));
9810 PUT_CODE (tem, NOTE);
9811 NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED;
9812 NOTE_SOURCE_FILE (tem) = 0;
9816 PUT_REG_NOTE_KIND (note, REG_UNUSED);
9818 /* If there isn't already a REG_UNUSED note, put one
9820 if (! find_regno_note (tem, REG_UNUSED,
9821 REGNO (XEXP (note, 0))))
9826 else if (reg_referenced_p (XEXP (note, 0), PATTERN (tem)))
9833 /* If the register is set or already dead at PLACE, we needn't do
9834 anything with this note if it is still a REG_DEAD note.
9836 Note that we cannot use just `dead_or_set_p' here since we can
9837 convert an assignment to a register into a bit-field assignment.
9838 Therefore, we must also omit the note if the register is the
9839 target of a bitfield assignment. */
9841 if (place && REG_NOTE_KIND (note) == REG_DEAD)
9843 int regno = REGNO (XEXP (note, 0));
9845 if (dead_or_set_p (place, XEXP (note, 0))
9846 || reg_bitfield_target_p (XEXP (note, 0), PATTERN (place)))
9848 /* Unless the register previously died in PLACE, clear
9849 reg_last_death. [I no longer understand why this is
9851 if (reg_last_death[regno] != place)
9852 reg_last_death[regno] = 0;
9856 reg_last_death[regno] = place;
9858 /* If this is a death note for a hard reg that is occupying
9859 multiple registers, ensure that we are still using all
9860 parts of the object. If we find a piece of the object
9861 that is unused, we must add a USE for that piece before
9862 PLACE and put the appropriate REG_DEAD note on it.
9864 An alternative would be to put a REG_UNUSED for the pieces
9865 on the insn that set the register, but that can't be done if
9866 it is not in the same block. It is simpler, though less
9867 efficient, to add the USE insns. */
9869 if (place && regno < FIRST_PSEUDO_REGISTER
9870 && HARD_REGNO_NREGS (regno, GET_MODE (XEXP (note, 0))) > 1)
9873 = regno + HARD_REGNO_NREGS (regno,
9874 GET_MODE (XEXP (note, 0)));
9878 for (i = regno; i < endregno; i++)
9879 if (! refers_to_regno_p (i, i + 1, PATTERN (place), 0))
9881 rtx piece = gen_rtx (REG, word_mode, i);
9884 /* See if we already placed a USE note for this
9885 register in front of PLACE. */
9887 GET_CODE (PREV_INSN (p)) == INSN
9888 && GET_CODE (PATTERN (PREV_INSN (p))) == USE;
9890 if (rtx_equal_p (piece,
9891 XEXP (PATTERN (PREV_INSN (p)), 0)))
9900 = emit_insn_before (gen_rtx (USE, VOIDmode,
9903 REG_NOTES (use_insn)
9904 = gen_rtx (EXPR_LIST, REG_DEAD, piece,
9905 REG_NOTES (use_insn));
9911 /* Check for the case where the register dying partially
9912 overlaps the register set by this insn. */
9914 for (i = regno; i < endregno; i++)
9915 if (dead_or_set_regno_p (place, i))
9923 /* Put only REG_DEAD notes for pieces that are
9924 still used and that are not already dead or set. */
9926 for (i = regno; i < endregno; i++)
9928 rtx piece = gen_rtx (REG, word_mode, i);
9930 if (reg_referenced_p (piece, PATTERN (place))
9931 && ! dead_or_set_p (place, piece)
9932 && ! reg_bitfield_target_p (piece,
9934 REG_NOTES (place) = gen_rtx (EXPR_LIST, REG_DEAD,
9946 /* Any other notes should not be present at this point in the
9953 XEXP (note, 1) = REG_NOTES (place);
9954 REG_NOTES (place) = note;
9956 else if ((REG_NOTE_KIND (note) == REG_DEAD
9957 || REG_NOTE_KIND (note) == REG_UNUSED)
9958 && GET_CODE (XEXP (note, 0)) == REG)
9959 reg_n_deaths[REGNO (XEXP (note, 0))]--;
9963 if ((REG_NOTE_KIND (note) == REG_DEAD
9964 || REG_NOTE_KIND (note) == REG_UNUSED)
9965 && GET_CODE (XEXP (note, 0)) == REG)
9966 reg_n_deaths[REGNO (XEXP (note, 0))]++;
9968 REG_NOTES (place2) = gen_rtx (GET_CODE (note), REG_NOTE_KIND (note),
9969 XEXP (note, 0), REG_NOTES (place2));
9974 /* Similarly to above, distribute the LOG_LINKS that used to be present on
9975 I3, I2, and I1 to new locations. This is also called in one case to
9976 add a link pointing at I3 when I3's destination is changed. */
9979 distribute_links (links)
9982 rtx link, next_link;
9984 for (link = links; link; link = next_link)
9990 next_link = XEXP (link, 1);
9992 /* If the insn that this link points to is a NOTE or isn't a single
9993 set, ignore it. In the latter case, it isn't clear what we
9994 can do other than ignore the link, since we can't tell which
9995 register it was for. Such links wouldn't be used by combine
9998 It is not possible for the destination of the target of the link to
9999 have been changed by combine. The only potential of this is if we
10000 replace I3, I2, and I1 by I3 and I2. But in that case the
10001 destination of I2 also remains unchanged. */
10003 if (GET_CODE (XEXP (link, 0)) == NOTE
10004 || (set = single_set (XEXP (link, 0))) == 0)
10007 reg = SET_DEST (set);
10008 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
10009 || GET_CODE (reg) == SIGN_EXTRACT
10010 || GET_CODE (reg) == STRICT_LOW_PART)
10011 reg = XEXP (reg, 0);
10013 /* A LOG_LINK is defined as being placed on the first insn that uses
10014 a register and points to the insn that sets the register. Start
10015 searching at the next insn after the target of the link and stop
10016 when we reach a set of the register or the end of the basic block.
10018 Note that this correctly handles the link that used to point from
10019 I3 to I2. Also note that not much searching is typically done here
10020 since most links don't point very far away. */
10022 for (insn = NEXT_INSN (XEXP (link, 0));
10023 (insn && GET_CODE (insn) != CODE_LABEL
10024 && GET_CODE (PREV_INSN (insn)) != JUMP_INSN);
10025 insn = NEXT_INSN (insn))
10026 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
10027 && reg_overlap_mentioned_p (reg, PATTERN (insn)))
10029 if (reg_referenced_p (reg, PATTERN (insn)))
10034 /* If we found a place to put the link, place it there unless there
10035 is already a link to the same insn as LINK at that point. */
10041 for (link2 = LOG_LINKS (place); link2; link2 = XEXP (link2, 1))
10042 if (XEXP (link2, 0) == XEXP (link, 0))
10047 XEXP (link, 1) = LOG_LINKS (place);
10048 LOG_LINKS (place) = link;
10055 dump_combine_stats (file)
10060 ";; Combiner statistics: %d attempts, %d substitutions (%d requiring new space),\n;; %d successes.\n\n",
10061 combine_attempts, combine_merges, combine_extras, combine_successes);
10065 dump_combine_total_stats (file)
10070 "\n;; Combiner totals: %d attempts, %d substitutions (%d requiring new space),\n;; %d successes.\n",
10071 total_attempts, total_merges, total_extras, total_successes);