1 /* Optimize by combining instructions for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
20 02111-1307, USA. */
21
22 /* This module is essentially the "combiner" phase of the U. of Arizona
23 Portable Optimizer, but redone to work on our list-structured
24 representation for RTL instead of their string representation.
25
26 The LOG_LINKS of each insn identify the most recent assignment
27 to each REG used in the insn. It is a list of previous insns,
28 each of which contains a SET for a REG that is used in this insn
29 and not used or set in between. LOG_LINKs never cross basic blocks.
30 They were set up by the preceding pass (lifetime analysis).
31
32 We try to combine each pair of insns joined by a logical link.
33 We also try to combine triples of insns A, B and C when
34 C has a link back to B and B has a link back to A.
35
36 LOG_LINKS does not have links for use of the CC0. They don't
37 need to, because the insn that sets the CC0 is always immediately
38 before the insn that tests it. So we always regard a branch
39 insn as having a logical link to the preceding insn. The same is true
40 for an insn explicitly using CC0.
41
42 We check (with use_crosses_set_p) to avoid combining in such a way
43 as to move a computation to a place where its value would be different.
44
45 Combination is done by mathematically substituting the previous
46 insn(s) values for the regs they set into the expressions in
47 the later insns that refer to these regs. If the result is a valid insn
48 for our target machine, according to the machine description,
49 we install it, delete the earlier insns, and update the data flow
50 information (LOG_LINKS and REG_NOTES) for what we did.
51
52 There are a few exceptions where the dataflow information created by
53 flow.c aren't completely updated:
54
55 - reg_live_length is not updated
56 - a LOG_LINKS entry that refers to an insn with multiple SETs may be
57 removed because there is no way to know which register it was
58 linking
59
60 To simplify substitution, we combine only when the earlier insn(s)
61 consist of only a single assignment. To simplify updating afterward,
62 we never combine when a subroutine call appears in the middle.
63
64 Since we do not represent assignments to CC0 explicitly except when that
65 is all an insn does, there is no LOG_LINKS entry in an insn that uses
66 the condition code for the insn that set the condition code.
67 Fortunately, these two insns must be consecutive.
68 Therefore, every JUMP_INSN is taken to have an implicit logical link
69 to the preceding insn. This is not quite right, since non-jumps can
70 also use the condition code; but in practice such insns would not
71 combine anyway. */
72
73 #include "config.h"
74 #include "system.h"
75 #include "coretypes.h"
76 #include "tm.h"
77 #include "rtl.h"
78 #include "tree.h"
79 #include "tm_p.h"
80 #include "flags.h"
81 #include "regs.h"
82 #include "hard-reg-set.h"
83 #include "basic-block.h"
84 #include "insn-config.h"
85 #include "function.h"
86 /* Include expr.h after insn-config.h so we get HAVE_conditional_move. */
87 #include "expr.h"
88 #include "insn-attr.h"
89 #include "recog.h"
90 #include "real.h"
91 #include "toplev.h"
92 #include "target.h"
93
94 #ifndef SHIFT_COUNT_TRUNCATED
95 #define SHIFT_COUNT_TRUNCATED 0
96 #endif
97
98 /* It is not safe to use ordinary gen_lowpart in combine.
99 Use gen_lowpart_for_combine instead. See comments there. */
100 #define gen_lowpart dont_use_gen_lowpart_you_dummy
101
102 /* Number of attempts to combine instructions in this function. */
103
104 static int combine_attempts;
105
106 /* Number of attempts that got as far as substitution in this function. */
107
108 static int combine_merges;
109
110 /* Number of instructions combined with added SETs in this function. */
111
112 static int combine_extras;
113
114 /* Number of instructions combined in this function. */
115
116 static int combine_successes;
117
118 /* Totals over entire compilation. */
119
120 static int total_attempts, total_merges, total_extras, total_successes;
121
122
123 /* Vector mapping INSN_UIDs to cuids.
124 The cuids are like uids but increase monotonically always.
125 Combine always uses cuids so that it can compare them.
126 But actually renumbering the uids, which we used to do,
127 proves to be a bad idea because it makes it hard to compare
128 the dumps produced by earlier passes with those from later passes. */
129
130 static int *uid_cuid;
131 static int max_uid_cuid;
132
133 /* Get the cuid of an insn. */
134
135 #define INSN_CUID(INSN) \
136 (INSN_UID (INSN) > max_uid_cuid ? insn_cuid (INSN) : uid_cuid[INSN_UID (INSN)])
137
138 /* In case BITS_PER_WORD == HOST_BITS_PER_WIDE_INT, shifting by
139 BITS_PER_WORD would invoke undefined behavior. Work around it. */
140
141 #define UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD(val) \
142 (((unsigned HOST_WIDE_INT) (val) << (BITS_PER_WORD - 1)) << 1)
143
144 #define nonzero_bits(X, M) \
145 cached_nonzero_bits (X, M, NULL_RTX, VOIDmode, 0)
146
147 #define num_sign_bit_copies(X, M) \
148 cached_num_sign_bit_copies (X, M, NULL_RTX, VOIDmode, 0)
149
150 /* Maximum register number, which is the size of the tables below. */
151
152 static unsigned int combine_max_regno;
153
154 /* Record last point of death of (hard or pseudo) register n. */
155
156 static rtx *reg_last_death;
157
158 /* Record last point of modification of (hard or pseudo) register n. */
159
160 static rtx *reg_last_set;
161
162 /* Record the cuid of the last insn that invalidated memory
163 (anything that writes memory, and subroutine calls, but not pushes). */
164
165 static int mem_last_set;
166
167 /* Record the cuid of the last CALL_INSN
168 so we can tell whether a potential combination crosses any calls. */
169
170 static int last_call_cuid;
171
172 /* When `subst' is called, this is the insn that is being modified
173 (by combining in a previous insn). The PATTERN of this insn
174 is still the old pattern partially modified and it should not be
175 looked at, but this may be used to examine the successors of the insn
176 to judge whether a simplification is valid. */
177
178 static rtx subst_insn;
179
180 /* This is the lowest CUID that `subst' is currently dealing with.
181 get_last_value will not return a value if the register was set at or
182 after this CUID. If not for this mechanism, we could get confused if
183 I2 or I1 in try_combine were an insn that used the old value of a register
184 to obtain a new value. In that case, we might erroneously get the
185 new value of the register when we wanted the old one. */
186
187 static int subst_low_cuid;
188
189 /* This contains any hard registers that are used in newpat; reg_dead_at_p
190 must consider all these registers to be always live. */
191
192 static HARD_REG_SET newpat_used_regs;
193
194 /* This is an insn to which a LOG_LINKS entry has been added. If this
195 insn is the earlier than I2 or I3, combine should rescan starting at
196 that location. */
197
198 static rtx added_links_insn;
199
200 /* Basic block in which we are performing combines. */
201 static basic_block this_basic_block;
202
203 /* A bitmap indicating which blocks had registers go dead at entry.
204 After combine, we'll need to re-do global life analysis with
205 those blocks as starting points. */
206 static sbitmap refresh_blocks;
207
208 /* The next group of arrays allows the recording of the last value assigned
209 to (hard or pseudo) register n. We use this information to see if an
210 operation being processed is redundant given a prior operation performed
211 on the register. For example, an `and' with a constant is redundant if
212 all the zero bits are already known to be turned off.
213
214 We use an approach similar to that used by cse, but change it in the
215 following ways:
216
217 (1) We do not want to reinitialize at each label.
218 (2) It is useful, but not critical, to know the actual value assigned
219 to a register. Often just its form is helpful.
220
221 Therefore, we maintain the following arrays:
222
223 reg_last_set_value the last value assigned
224 reg_last_set_label records the value of label_tick when the
225 register was assigned
226 reg_last_set_table_tick records the value of label_tick when a
227 value using the register is assigned
228 reg_last_set_invalid set to nonzero when it is not valid
229 to use the value of this register in some
230 register's value
231
232 To understand the usage of these tables, it is important to understand
233 the distinction between the value in reg_last_set_value being valid
234 and the register being validly contained in some other expression in the
235 table.
236
237 Entry I in reg_last_set_value is valid if it is nonzero, and either
238 reg_n_sets[i] is 1 or reg_last_set_label[i] == label_tick.
239
240 Register I may validly appear in any expression returned for the value
241 of another register if reg_n_sets[i] is 1. It may also appear in the
242 value for register J if reg_last_set_label[i] < reg_last_set_label[j] or
243 reg_last_set_invalid[j] is zero.
244
245 If an expression is found in the table containing a register which may
246 not validly appear in an expression, the register is replaced by
247 something that won't match, (clobber (const_int 0)).
248
249 reg_last_set_invalid[i] is set nonzero when register I is being assigned
250 to and reg_last_set_table_tick[i] == label_tick. */
251
252 /* Record last value assigned to (hard or pseudo) register n. */
253
254 static rtx *reg_last_set_value;
255
256 /* Record the value of label_tick when the value for register n is placed in
257 reg_last_set_value[n]. */
258
259 static int *reg_last_set_label;
260
261 /* Record the value of label_tick when an expression involving register n
262 is placed in reg_last_set_value. */
263
264 static int *reg_last_set_table_tick;
265
266 /* Set nonzero if references to register n in expressions should not be
267 used. */
268
269 static char *reg_last_set_invalid;
270
271 /* Incremented for each label. */
272
273 static int label_tick;
274
275 /* Some registers that are set more than once and used in more than one
276 basic block are nevertheless always set in similar ways. For example,
277 a QImode register may be loaded from memory in two places on a machine
278 where byte loads zero extend.
279
280 We record in the following array what we know about the nonzero
281 bits of a register, specifically which bits are known to be zero.
282
283 If an entry is zero, it means that we don't know anything special. */
284
285 static unsigned HOST_WIDE_INT *reg_nonzero_bits;
286
287 /* Mode used to compute significance in reg_nonzero_bits. It is the largest
288 integer mode that can fit in HOST_BITS_PER_WIDE_INT. */
289
290 static enum machine_mode nonzero_bits_mode;
291
292 /* Nonzero if we know that a register has some leading bits that are always
293 equal to the sign bit. */
294
295 static unsigned char *reg_sign_bit_copies;
296
297 /* Nonzero when reg_nonzero_bits and reg_sign_bit_copies can be safely used.
298 It is zero while computing them and after combine has completed. This
299 former test prevents propagating values based on previously set values,
300 which can be incorrect if a variable is modified in a loop. */
301
302 static int nonzero_sign_valid;
303
304 /* These arrays are maintained in parallel with reg_last_set_value
305 and are used to store the mode in which the register was last set,
306 the bits that were known to be zero when it was last set, and the
307 number of sign bits copies it was known to have when it was last set. */
308
309 static enum machine_mode *reg_last_set_mode;
310 static unsigned HOST_WIDE_INT *reg_last_set_nonzero_bits;
311 static char *reg_last_set_sign_bit_copies;
312
313 /* Record one modification to rtl structure
314 to be undone by storing old_contents into *where.
315 is_int is 1 if the contents are an int. */
316
317 struct undo
318 {
319 struct undo *next;
320 int is_int;
321 union {rtx r; int i;} old_contents;
322 union {rtx *r; int *i;} where;
323 };
324
325 /* Record a bunch of changes to be undone, up to MAX_UNDO of them.
326 num_undo says how many are currently recorded.
327
328 other_insn is nonzero if we have modified some other insn in the process
329 of working on subst_insn. It must be verified too. */
330
331 struct undobuf
332 {
333 struct undo *undos;
334 struct undo *frees;
335 rtx other_insn;
336 };
337
338 static struct undobuf undobuf;
339
340 /* Number of times the pseudo being substituted for
341 was found and replaced. */
342
343 static int n_occurrences;
344
345 static void do_SUBST (rtx *, rtx);
346 static void do_SUBST_INT (int *, int);
347 static void init_reg_last_arrays (void);
348 static void setup_incoming_promotions (void);
349 static void set_nonzero_bits_and_sign_copies (rtx, rtx, void *);
350 static int cant_combine_insn_p (rtx);
351 static int can_combine_p (rtx, rtx, rtx, rtx, rtx *, rtx *);
352 static int combinable_i3pat (rtx, rtx *, rtx, rtx, int, rtx *);
353 static int contains_muldiv (rtx);
354 static rtx try_combine (rtx, rtx, rtx, int *);
355 static void undo_all (void);
356 static void undo_commit (void);
357 static rtx *find_split_point (rtx *, rtx);
358 static rtx subst (rtx, rtx, rtx, int, int);
359 static rtx combine_simplify_rtx (rtx, enum machine_mode, int, int);
360 static rtx simplify_if_then_else (rtx);
361 static rtx simplify_set (rtx);
362 static rtx simplify_logical (rtx, int);
363 static rtx expand_compound_operation (rtx);
364 static rtx expand_field_assignment (rtx);
365 static rtx make_extraction (enum machine_mode, rtx, HOST_WIDE_INT,
366 rtx, unsigned HOST_WIDE_INT, int, int, int);
367 static rtx extract_left_shift (rtx, int);
368 static rtx make_compound_operation (rtx, enum rtx_code);
369 static int get_pos_from_mask (unsigned HOST_WIDE_INT,
370 unsigned HOST_WIDE_INT *);
371 static rtx force_to_mode (rtx, enum machine_mode,
372 unsigned HOST_WIDE_INT, rtx, int);
373 static rtx if_then_else_cond (rtx, rtx *, rtx *);
374 static rtx known_cond (rtx, enum rtx_code, rtx, rtx);
375 static int rtx_equal_for_field_assignment_p (rtx, rtx);
376 static rtx make_field_assignment (rtx);
377 static rtx apply_distributive_law (rtx);
378 static rtx simplify_and_const_int (rtx, enum machine_mode, rtx,
379 unsigned HOST_WIDE_INT);
380 static unsigned HOST_WIDE_INT cached_nonzero_bits (rtx, enum machine_mode,
381 rtx, enum machine_mode,
382 unsigned HOST_WIDE_INT);
383 static unsigned HOST_WIDE_INT nonzero_bits1 (rtx, enum machine_mode, rtx,
384 enum machine_mode,
385 unsigned HOST_WIDE_INT);
386 static unsigned int cached_num_sign_bit_copies (rtx, enum machine_mode, rtx,
387 enum machine_mode,
388 unsigned int);
389 static unsigned int num_sign_bit_copies1 (rtx, enum machine_mode, rtx,
390 enum machine_mode, unsigned int);
391 static int merge_outer_ops (enum rtx_code *, HOST_WIDE_INT *, enum rtx_code,
392 HOST_WIDE_INT, enum machine_mode, int *);
393 static rtx simplify_shift_const (rtx, enum rtx_code, enum machine_mode, rtx,
394 int);
395 static int recog_for_combine (rtx *, rtx, rtx *);
396 static rtx gen_lowpart_for_combine (enum machine_mode, rtx);
397 static rtx gen_binary (enum rtx_code, enum machine_mode, rtx, rtx);
398 static enum rtx_code simplify_comparison (enum rtx_code, rtx *, rtx *);
399 static void update_table_tick (rtx);
400 static void record_value_for_reg (rtx, rtx, rtx);
401 static void check_promoted_subreg (rtx, rtx);
402 static void record_dead_and_set_regs_1 (rtx, rtx, void *);
403 static void record_dead_and_set_regs (rtx);
404 static int get_last_value_validate (rtx *, rtx, int, int);
405 static rtx get_last_value (rtx);
406 static int use_crosses_set_p (rtx, int);
407 static void reg_dead_at_p_1 (rtx, rtx, void *);
408 static int reg_dead_at_p (rtx, rtx);
409 static void move_deaths (rtx, rtx, int, rtx, rtx *);
410 static int reg_bitfield_target_p (rtx, rtx);
411 static void distribute_notes (rtx, rtx, rtx, rtx);
412 static void distribute_links (rtx);
413 static void mark_used_regs_combine (rtx);
414 static int insn_cuid (rtx);
415 static void record_promoted_value (rtx, rtx);
416 static rtx reversed_comparison (rtx, enum machine_mode, rtx, rtx);
417 static enum rtx_code combine_reversed_comparison_code (rtx);
418
419 /* Substitute NEWVAL, an rtx expression, into INTO, a place in some
420 insn. The substitution can be undone by undo_all. If INTO is already
421 set to NEWVAL, do not record this change. Because computing NEWVAL might
422 also call SUBST, we have to compute it before we put anything into
423 the undo table. */
424
425 static void
do_SUBST(rtx * into,rtx newval)426 do_SUBST (rtx *into, rtx newval)
427 {
428 struct undo *buf;
429 rtx oldval = *into;
430
431 if (oldval == newval)
432 return;
433
434 /* We'd like to catch as many invalid transformations here as
435 possible. Unfortunately, there are way too many mode changes
436 that are perfectly valid, so we'd waste too much effort for
437 little gain doing the checks here. Focus on catching invalid
438 transformations involving integer constants. */
439 if (GET_MODE_CLASS (GET_MODE (oldval)) == MODE_INT
440 && GET_CODE (newval) == CONST_INT)
441 {
442 /* Sanity check that we're replacing oldval with a CONST_INT
443 that is a valid sign-extension for the original mode. */
444 if (INTVAL (newval) != trunc_int_for_mode (INTVAL (newval),
445 GET_MODE (oldval)))
446 abort ();
447
448 /* Replacing the operand of a SUBREG or a ZERO_EXTEND with a
449 CONST_INT is not valid, because after the replacement, the
450 original mode would be gone. Unfortunately, we can't tell
451 when do_SUBST is called to replace the operand thereof, so we
452 perform this test on oldval instead, checking whether an
453 invalid replacement took place before we got here. */
454 if ((GET_CODE (oldval) == SUBREG
455 && GET_CODE (SUBREG_REG (oldval)) == CONST_INT)
456 || (GET_CODE (oldval) == ZERO_EXTEND
457 && GET_CODE (XEXP (oldval, 0)) == CONST_INT))
458 abort ();
459 }
460
461 if (undobuf.frees)
462 buf = undobuf.frees, undobuf.frees = buf->next;
463 else
464 buf = xmalloc (sizeof (struct undo));
465
466 buf->is_int = 0;
467 buf->where.r = into;
468 buf->old_contents.r = oldval;
469 *into = newval;
470
471 buf->next = undobuf.undos, undobuf.undos = buf;
472 }
473
474 #define SUBST(INTO, NEWVAL) do_SUBST(&(INTO), (NEWVAL))
475
476 /* Similar to SUBST, but NEWVAL is an int expression. Note that substitution
477 for the value of a HOST_WIDE_INT value (including CONST_INT) is
478 not safe. */
479
480 static void
do_SUBST_INT(int * into,int newval)481 do_SUBST_INT (int *into, int newval)
482 {
483 struct undo *buf;
484 int oldval = *into;
485
486 if (oldval == newval)
487 return;
488
489 if (undobuf.frees)
490 buf = undobuf.frees, undobuf.frees = buf->next;
491 else
492 buf = xmalloc (sizeof (struct undo));
493
494 buf->is_int = 1;
495 buf->where.i = into;
496 buf->old_contents.i = oldval;
497 *into = newval;
498
499 buf->next = undobuf.undos, undobuf.undos = buf;
500 }
501
502 #define SUBST_INT(INTO, NEWVAL) do_SUBST_INT(&(INTO), (NEWVAL))
503
504 /* Main entry point for combiner. F is the first insn of the function.
505 NREGS is the first unused pseudo-reg number.
506
507 Return nonzero if the combiner has turned an indirect jump
508 instruction into a direct jump. */
509 int
combine_instructions(rtx f,unsigned int nregs)510 combine_instructions (rtx f, unsigned int nregs)
511 {
512 rtx insn, next;
513 #ifdef HAVE_cc0
514 rtx prev;
515 #endif
516 int i;
517 rtx links, nextlinks;
518
519 int new_direct_jump_p = 0;
520
521 combine_attempts = 0;
522 combine_merges = 0;
523 combine_extras = 0;
524 combine_successes = 0;
525
526 combine_max_regno = nregs;
527
528 reg_nonzero_bits = xcalloc (nregs, sizeof (unsigned HOST_WIDE_INT));
529 reg_sign_bit_copies = xcalloc (nregs, sizeof (unsigned char));
530
531 reg_last_death = xmalloc (nregs * sizeof (rtx));
532 reg_last_set = xmalloc (nregs * sizeof (rtx));
533 reg_last_set_value = xmalloc (nregs * sizeof (rtx));
534 reg_last_set_table_tick = xmalloc (nregs * sizeof (int));
535 reg_last_set_label = xmalloc (nregs * sizeof (int));
536 reg_last_set_invalid = xmalloc (nregs * sizeof (char));
537 reg_last_set_mode = xmalloc (nregs * sizeof (enum machine_mode));
538 reg_last_set_nonzero_bits = xmalloc (nregs * sizeof (HOST_WIDE_INT));
539 reg_last_set_sign_bit_copies = xmalloc (nregs * sizeof (char));
540
541 init_reg_last_arrays ();
542
543 init_recog_no_volatile ();
544
545 /* Compute maximum uid value so uid_cuid can be allocated. */
546
547 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
548 if (INSN_UID (insn) > i)
549 i = INSN_UID (insn);
550
551 uid_cuid = xmalloc ((i + 1) * sizeof (int));
552 max_uid_cuid = i;
553
554 nonzero_bits_mode = mode_for_size (HOST_BITS_PER_WIDE_INT, MODE_INT, 0);
555
556 /* Don't use reg_nonzero_bits when computing it. This can cause problems
557 when, for example, we have j <<= 1 in a loop. */
558
559 nonzero_sign_valid = 0;
560
561 /* Compute the mapping from uids to cuids.
562 Cuids are numbers assigned to insns, like uids,
563 except that cuids increase monotonically through the code.
564
565 Scan all SETs and see if we can deduce anything about what
566 bits are known to be zero for some registers and how many copies
567 of the sign bit are known to exist for those registers.
568
569 Also set any known values so that we can use it while searching
570 for what bits are known to be set. */
571
572 label_tick = 1;
573
574 setup_incoming_promotions ();
575
576 refresh_blocks = sbitmap_alloc (last_basic_block);
577 sbitmap_zero (refresh_blocks);
578
579 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
580 {
581 uid_cuid[INSN_UID (insn)] = ++i;
582 subst_low_cuid = i;
583 subst_insn = insn;
584
585 if (INSN_P (insn))
586 {
587 note_stores (PATTERN (insn), set_nonzero_bits_and_sign_copies,
588 NULL);
589 record_dead_and_set_regs (insn);
590
591 #ifdef AUTO_INC_DEC
592 for (links = REG_NOTES (insn); links; links = XEXP (links, 1))
593 if (REG_NOTE_KIND (links) == REG_INC)
594 set_nonzero_bits_and_sign_copies (XEXP (links, 0), NULL_RTX,
595 NULL);
596 #endif
597 }
598
599 if (GET_CODE (insn) == CODE_LABEL)
600 label_tick++;
601 }
602
603 nonzero_sign_valid = 1;
604
605 /* Now scan all the insns in forward order. */
606
607 label_tick = 1;
608 last_call_cuid = 0;
609 mem_last_set = 0;
610 init_reg_last_arrays ();
611 setup_incoming_promotions ();
612
613 FOR_EACH_BB (this_basic_block)
614 {
615 for (insn = BB_HEAD (this_basic_block);
616 insn != NEXT_INSN (BB_END (this_basic_block));
617 insn = next ? next : NEXT_INSN (insn))
618 {
619 next = 0;
620
621 if (GET_CODE (insn) == CODE_LABEL)
622 label_tick++;
623
624 else if (INSN_P (insn))
625 {
626 /* See if we know about function return values before this
627 insn based upon SUBREG flags. */
628 check_promoted_subreg (insn, PATTERN (insn));
629
630 /* Try this insn with each insn it links back to. */
631
632 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
633 if ((next = try_combine (insn, XEXP (links, 0),
634 NULL_RTX, &new_direct_jump_p)) != 0)
635 goto retry;
636
637 /* Try each sequence of three linked insns ending with this one. */
638
639 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
640 {
641 rtx link = XEXP (links, 0);
642
643 /* If the linked insn has been replaced by a note, then there
644 is no point in pursuing this chain any further. */
645 if (GET_CODE (link) == NOTE)
646 continue;
647
648 for (nextlinks = LOG_LINKS (link);
649 nextlinks;
650 nextlinks = XEXP (nextlinks, 1))
651 if ((next = try_combine (insn, link,
652 XEXP (nextlinks, 0),
653 &new_direct_jump_p)) != 0)
654 goto retry;
655 }
656
657 #ifdef HAVE_cc0
658 /* Try to combine a jump insn that uses CC0
659 with a preceding insn that sets CC0, and maybe with its
660 logical predecessor as well.
661 This is how we make decrement-and-branch insns.
662 We need this special code because data flow connections
663 via CC0 do not get entered in LOG_LINKS. */
664
665 if (GET_CODE (insn) == JUMP_INSN
666 && (prev = prev_nonnote_insn (insn)) != 0
667 && GET_CODE (prev) == INSN
668 && sets_cc0_p (PATTERN (prev)))
669 {
670 if ((next = try_combine (insn, prev,
671 NULL_RTX, &new_direct_jump_p)) != 0)
672 goto retry;
673
674 for (nextlinks = LOG_LINKS (prev); nextlinks;
675 nextlinks = XEXP (nextlinks, 1))
676 if ((next = try_combine (insn, prev,
677 XEXP (nextlinks, 0),
678 &new_direct_jump_p)) != 0)
679 goto retry;
680 }
681
682 /* Do the same for an insn that explicitly references CC0. */
683 if (GET_CODE (insn) == INSN
684 && (prev = prev_nonnote_insn (insn)) != 0
685 && GET_CODE (prev) == INSN
686 && sets_cc0_p (PATTERN (prev))
687 && GET_CODE (PATTERN (insn)) == SET
688 && reg_mentioned_p (cc0_rtx, SET_SRC (PATTERN (insn))))
689 {
690 if ((next = try_combine (insn, prev,
691 NULL_RTX, &new_direct_jump_p)) != 0)
692 goto retry;
693
694 for (nextlinks = LOG_LINKS (prev); nextlinks;
695 nextlinks = XEXP (nextlinks, 1))
696 if ((next = try_combine (insn, prev,
697 XEXP (nextlinks, 0),
698 &new_direct_jump_p)) != 0)
699 goto retry;
700 }
701
702 /* Finally, see if any of the insns that this insn links to
703 explicitly references CC0. If so, try this insn, that insn,
704 and its predecessor if it sets CC0. */
705 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
706 if (GET_CODE (XEXP (links, 0)) == INSN
707 && GET_CODE (PATTERN (XEXP (links, 0))) == SET
708 && reg_mentioned_p (cc0_rtx, SET_SRC (PATTERN (XEXP (links, 0))))
709 && (prev = prev_nonnote_insn (XEXP (links, 0))) != 0
710 && GET_CODE (prev) == INSN
711 && sets_cc0_p (PATTERN (prev))
712 && (next = try_combine (insn, XEXP (links, 0),
713 prev, &new_direct_jump_p)) != 0)
714 goto retry;
715 #endif
716
717 /* Try combining an insn with two different insns whose results it
718 uses. */
719 for (links = LOG_LINKS (insn); links; links = XEXP (links, 1))
720 for (nextlinks = XEXP (links, 1); nextlinks;
721 nextlinks = XEXP (nextlinks, 1))
722 if ((next = try_combine (insn, XEXP (links, 0),
723 XEXP (nextlinks, 0),
724 &new_direct_jump_p)) != 0)
725 goto retry;
726
727 if (GET_CODE (insn) != NOTE)
728 record_dead_and_set_regs (insn);
729
730 retry:
731 ;
732 }
733 }
734 }
735 clear_bb_flags ();
736
737 EXECUTE_IF_SET_IN_SBITMAP (refresh_blocks, 0, i,
738 BASIC_BLOCK (i)->flags |= BB_DIRTY);
739 new_direct_jump_p |= purge_all_dead_edges (0);
740 delete_noop_moves (f);
741
742 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
743 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
744 | PROP_KILL_DEAD_CODE);
745
746 /* Clean up. */
747 sbitmap_free (refresh_blocks);
748 free (reg_nonzero_bits);
749 free (reg_sign_bit_copies);
750 free (reg_last_death);
751 free (reg_last_set);
752 free (reg_last_set_value);
753 free (reg_last_set_table_tick);
754 free (reg_last_set_label);
755 free (reg_last_set_invalid);
756 free (reg_last_set_mode);
757 free (reg_last_set_nonzero_bits);
758 free (reg_last_set_sign_bit_copies);
759 free (uid_cuid);
760
761 {
762 struct undo *undo, *next;
763 for (undo = undobuf.frees; undo; undo = next)
764 {
765 next = undo->next;
766 free (undo);
767 }
768 undobuf.frees = 0;
769 }
770
771 total_attempts += combine_attempts;
772 total_merges += combine_merges;
773 total_extras += combine_extras;
774 total_successes += combine_successes;
775
776 nonzero_sign_valid = 0;
777
778 /* Make recognizer allow volatile MEMs again. */
779 init_recog ();
780
781 return new_direct_jump_p;
782 }
783
784 /* Wipe the reg_last_xxx arrays in preparation for another pass. */
785
786 static void
init_reg_last_arrays(void)787 init_reg_last_arrays (void)
788 {
789 unsigned int nregs = combine_max_regno;
790
791 memset (reg_last_death, 0, nregs * sizeof (rtx));
792 memset (reg_last_set, 0, nregs * sizeof (rtx));
793 memset (reg_last_set_value, 0, nregs * sizeof (rtx));
794 memset (reg_last_set_table_tick, 0, nregs * sizeof (int));
795 memset (reg_last_set_label, 0, nregs * sizeof (int));
796 memset (reg_last_set_invalid, 0, nregs * sizeof (char));
797 memset (reg_last_set_mode, 0, nregs * sizeof (enum machine_mode));
798 memset (reg_last_set_nonzero_bits, 0, nregs * sizeof (HOST_WIDE_INT));
799 memset (reg_last_set_sign_bit_copies, 0, nregs * sizeof (char));
800 }
801
802 /* Set up any promoted values for incoming argument registers. */
803
804 static void
setup_incoming_promotions(void)805 setup_incoming_promotions (void)
806 {
807 unsigned int regno;
808 rtx reg;
809 enum machine_mode mode;
810 int unsignedp;
811 rtx first = get_insns ();
812
813 if (targetm.calls.promote_function_args (TREE_TYPE (cfun->decl)))
814 {
815 #ifndef OUTGOING_REGNO
816 #define OUTGOING_REGNO(N) N
817 #endif
818 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
819 /* Check whether this register can hold an incoming pointer
820 argument. FUNCTION_ARG_REGNO_P tests outgoing register
821 numbers, so translate if necessary due to register windows. */
822 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (regno))
823 && (reg = promoted_input_arg (regno, &mode, &unsignedp)) != 0)
824 {
825 record_value_for_reg
826 (reg, first, gen_rtx_fmt_e ((unsignedp ? ZERO_EXTEND
827 : SIGN_EXTEND),
828 GET_MODE (reg),
829 gen_rtx_CLOBBER (mode, const0_rtx)));
830 }
831 }
832 }
833
834 /* Called via note_stores. If X is a pseudo that is narrower than
835 HOST_BITS_PER_WIDE_INT and is being set, record what bits are known zero.
836
837 If we are setting only a portion of X and we can't figure out what
838 portion, assume all bits will be used since we don't know what will
839 be happening.
840
841 Similarly, set how many bits of X are known to be copies of the sign bit
842 at all locations in the function. This is the smallest number implied
843 by any set of X. */
844
845 static void
set_nonzero_bits_and_sign_copies(rtx x,rtx set,void * data ATTRIBUTE_UNUSED)846 set_nonzero_bits_and_sign_copies (rtx x, rtx set,
847 void *data ATTRIBUTE_UNUSED)
848 {
849 unsigned int num;
850
851 if (GET_CODE (x) == REG
852 && REGNO (x) >= FIRST_PSEUDO_REGISTER
853 /* If this register is undefined at the start of the file, we can't
854 say what its contents were. */
855 && ! REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, REGNO (x))
856 && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT)
857 {
858 if (set == 0 || GET_CODE (set) == CLOBBER)
859 {
860 reg_nonzero_bits[REGNO (x)] = GET_MODE_MASK (GET_MODE (x));
861 reg_sign_bit_copies[REGNO (x)] = 1;
862 return;
863 }
864
865 /* If this is a complex assignment, see if we can convert it into a
866 simple assignment. */
867 set = expand_field_assignment (set);
868
869 /* If this is a simple assignment, or we have a paradoxical SUBREG,
870 set what we know about X. */
871
872 if (SET_DEST (set) == x
873 || (GET_CODE (SET_DEST (set)) == SUBREG
874 && (GET_MODE_SIZE (GET_MODE (SET_DEST (set)))
875 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (set)))))
876 && SUBREG_REG (SET_DEST (set)) == x))
877 {
878 rtx src = SET_SRC (set);
879
880 #ifdef SHORT_IMMEDIATES_SIGN_EXTEND
881 /* If X is narrower than a word and SRC is a non-negative
882 constant that would appear negative in the mode of X,
883 sign-extend it for use in reg_nonzero_bits because some
884 machines (maybe most) will actually do the sign-extension
885 and this is the conservative approach.
886
887 ??? For 2.5, try to tighten up the MD files in this regard
888 instead of this kludge. */
889
890 if (GET_MODE_BITSIZE (GET_MODE (x)) < BITS_PER_WORD
891 && GET_CODE (src) == CONST_INT
892 && INTVAL (src) > 0
893 && 0 != (INTVAL (src)
894 & ((HOST_WIDE_INT) 1
895 << (GET_MODE_BITSIZE (GET_MODE (x)) - 1))))
896 src = GEN_INT (INTVAL (src)
897 | ((HOST_WIDE_INT) (-1)
898 << GET_MODE_BITSIZE (GET_MODE (x))));
899 #endif
900
901 /* Don't call nonzero_bits if it cannot change anything. */
902 if (reg_nonzero_bits[REGNO (x)] != ~(unsigned HOST_WIDE_INT) 0)
903 reg_nonzero_bits[REGNO (x)]
904 |= nonzero_bits (src, nonzero_bits_mode);
905 num = num_sign_bit_copies (SET_SRC (set), GET_MODE (x));
906 if (reg_sign_bit_copies[REGNO (x)] == 0
907 || reg_sign_bit_copies[REGNO (x)] > num)
908 reg_sign_bit_copies[REGNO (x)] = num;
909 }
910 else
911 {
912 reg_nonzero_bits[REGNO (x)] = GET_MODE_MASK (GET_MODE (x));
913 reg_sign_bit_copies[REGNO (x)] = 1;
914 }
915 }
916 }
917
918 /* See if INSN can be combined into I3. PRED and SUCC are optionally
919 insns that were previously combined into I3 or that will be combined
920 into the merger of INSN and I3.
921
922 Return 0 if the combination is not allowed for any reason.
923
924 If the combination is allowed, *PDEST will be set to the single
925 destination of INSN and *PSRC to the single source, and this function
926 will return 1. */
927
928 static int
can_combine_p(rtx insn,rtx i3,rtx pred ATTRIBUTE_UNUSED,rtx succ,rtx * pdest,rtx * psrc)929 can_combine_p (rtx insn, rtx i3, rtx pred ATTRIBUTE_UNUSED, rtx succ,
930 rtx *pdest, rtx *psrc)
931 {
932 int i;
933 rtx set = 0, src, dest;
934 rtx p;
935 #ifdef AUTO_INC_DEC
936 rtx link;
937 #endif
938 int all_adjacent = (succ ? (next_active_insn (insn) == succ
939 && next_active_insn (succ) == i3)
940 : next_active_insn (insn) == i3);
941
942 /* Can combine only if previous insn is a SET of a REG, a SUBREG or CC0.
943 or a PARALLEL consisting of such a SET and CLOBBERs.
944
945 If INSN has CLOBBER parallel parts, ignore them for our processing.
946 By definition, these happen during the execution of the insn. When it
947 is merged with another insn, all bets are off. If they are, in fact,
948 needed and aren't also supplied in I3, they may be added by
949 recog_for_combine. Otherwise, it won't match.
950
951 We can also ignore a SET whose SET_DEST is mentioned in a REG_UNUSED
952 note.
953
954 Get the source and destination of INSN. If more than one, can't
955 combine. */
956
957 if (GET_CODE (PATTERN (insn)) == SET)
958 set = PATTERN (insn);
959 else if (GET_CODE (PATTERN (insn)) == PARALLEL
960 && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == SET)
961 {
962 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
963 {
964 rtx elt = XVECEXP (PATTERN (insn), 0, i);
965 rtx note;
966
967 switch (GET_CODE (elt))
968 {
969 /* This is important to combine floating point insns
970 for the SH4 port. */
971 case USE:
972 /* Combining an isolated USE doesn't make sense.
973 We depend here on combinable_i3pat to reject them. */
974 /* The code below this loop only verifies that the inputs of
975 the SET in INSN do not change. We call reg_set_between_p
976 to verify that the REG in the USE does not change between
977 I3 and INSN.
978 If the USE in INSN was for a pseudo register, the matching
979 insn pattern will likely match any register; combining this
980 with any other USE would only be safe if we knew that the
981 used registers have identical values, or if there was
982 something to tell them apart, e.g. different modes. For
983 now, we forgo such complicated tests and simply disallow
984 combining of USES of pseudo registers with any other USE. */
985 if (GET_CODE (XEXP (elt, 0)) == REG
986 && GET_CODE (PATTERN (i3)) == PARALLEL)
987 {
988 rtx i3pat = PATTERN (i3);
989 int i = XVECLEN (i3pat, 0) - 1;
990 unsigned int regno = REGNO (XEXP (elt, 0));
991
992 do
993 {
994 rtx i3elt = XVECEXP (i3pat, 0, i);
995
996 if (GET_CODE (i3elt) == USE
997 && GET_CODE (XEXP (i3elt, 0)) == REG
998 && (REGNO (XEXP (i3elt, 0)) == regno
999 ? reg_set_between_p (XEXP (elt, 0),
1000 PREV_INSN (insn), i3)
1001 : regno >= FIRST_PSEUDO_REGISTER))
1002 return 0;
1003 }
1004 while (--i >= 0);
1005 }
1006 break;
1007
1008 /* We can ignore CLOBBERs. */
1009 case CLOBBER:
1010 break;
1011
1012 case SET:
1013 /* Ignore SETs whose result isn't used but not those that
1014 have side-effects. */
1015 if (find_reg_note (insn, REG_UNUSED, SET_DEST (elt))
1016 && (!(note = find_reg_note (insn, REG_EH_REGION, NULL_RTX))
1017 || INTVAL (XEXP (note, 0)) <= 0)
1018 && ! side_effects_p (elt))
1019 break;
1020
1021 /* If we have already found a SET, this is a second one and
1022 so we cannot combine with this insn. */
1023 if (set)
1024 return 0;
1025
1026 set = elt;
1027 break;
1028
1029 default:
1030 /* Anything else means we can't combine. */
1031 return 0;
1032 }
1033 }
1034
1035 if (set == 0
1036 /* If SET_SRC is an ASM_OPERANDS we can't throw away these CLOBBERs,
1037 so don't do anything with it. */
1038 || GET_CODE (SET_SRC (set)) == ASM_OPERANDS)
1039 return 0;
1040 }
1041 else
1042 return 0;
1043
1044 if (set == 0)
1045 return 0;
1046
1047 set = expand_field_assignment (set);
1048 src = SET_SRC (set), dest = SET_DEST (set);
1049
1050 /* Don't eliminate a store in the stack pointer. */
1051 if (dest == stack_pointer_rtx
1052 /* Don't combine with an insn that sets a register to itself if it has
1053 a REG_EQUAL note. This may be part of a REG_NO_CONFLICT sequence. */
1054 || (rtx_equal_p (src, dest) && find_reg_note (insn, REG_EQUAL, NULL_RTX))
1055 /* Can't merge an ASM_OPERANDS. */
1056 || GET_CODE (src) == ASM_OPERANDS
1057 /* Can't merge a function call. */
1058 || GET_CODE (src) == CALL
1059 /* Don't eliminate a function call argument. */
1060 || (GET_CODE (i3) == CALL_INSN
1061 && (find_reg_fusage (i3, USE, dest)
1062 || (GET_CODE (dest) == REG
1063 && REGNO (dest) < FIRST_PSEUDO_REGISTER
1064 && global_regs[REGNO (dest)])))
1065 /* Don't substitute into an incremented register. */
1066 || FIND_REG_INC_NOTE (i3, dest)
1067 || (succ && FIND_REG_INC_NOTE (succ, dest))
1068 #if 0
1069 /* Don't combine the end of a libcall into anything. */
1070 /* ??? This gives worse code, and appears to be unnecessary, since no
1071 pass after flow uses REG_LIBCALL/REG_RETVAL notes. Local-alloc does
1072 use REG_RETVAL notes for noconflict blocks, but other code here
1073 makes sure that those insns don't disappear. */
1074 || find_reg_note (insn, REG_RETVAL, NULL_RTX)
1075 #endif
1076 /* Make sure that DEST is not used after SUCC but before I3. */
1077 || (succ && ! all_adjacent
1078 && reg_used_between_p (dest, succ, i3))
1079 /* Make sure that the value that is to be substituted for the register
1080 does not use any registers whose values alter in between. However,
1081 If the insns are adjacent, a use can't cross a set even though we
1082 think it might (this can happen for a sequence of insns each setting
1083 the same destination; reg_last_set of that register might point to
1084 a NOTE). If INSN has a REG_EQUIV note, the register is always
1085 equivalent to the memory so the substitution is valid even if there
1086 are intervening stores. Also, don't move a volatile asm or
1087 UNSPEC_VOLATILE across any other insns. */
1088 || (! all_adjacent
1089 && (((GET_CODE (src) != MEM
1090 || ! find_reg_note (insn, REG_EQUIV, src))
1091 && use_crosses_set_p (src, INSN_CUID (insn)))
1092 || (GET_CODE (src) == ASM_OPERANDS && MEM_VOLATILE_P (src))
1093 || GET_CODE (src) == UNSPEC_VOLATILE))
1094 /* If there is a REG_NO_CONFLICT note for DEST in I3 or SUCC, we get
1095 better register allocation by not doing the combine. */
1096 || find_reg_note (i3, REG_NO_CONFLICT, dest)
1097 || (succ && find_reg_note (succ, REG_NO_CONFLICT, dest))
1098 /* Don't combine across a CALL_INSN, because that would possibly
1099 change whether the life span of some REGs crosses calls or not,
1100 and it is a pain to update that information.
1101 Exception: if source is a constant, moving it later can't hurt.
1102 Accept that special case, because it helps -fforce-addr a lot. */
1103 || (INSN_CUID (insn) < last_call_cuid && ! CONSTANT_P (src)))
1104 return 0;
1105
1106 /* DEST must either be a REG or CC0. */
1107 if (GET_CODE (dest) == REG)
1108 {
1109 /* If register alignment is being enforced for multi-word items in all
1110 cases except for parameters, it is possible to have a register copy
1111 insn referencing a hard register that is not allowed to contain the
1112 mode being copied and which would not be valid as an operand of most
1113 insns. Eliminate this problem by not combining with such an insn.
1114
1115 Also, on some machines we don't want to extend the life of a hard
1116 register. */
1117
1118 if (GET_CODE (src) == REG
1119 && ((REGNO (dest) < FIRST_PSEUDO_REGISTER
1120 && ! HARD_REGNO_MODE_OK (REGNO (dest), GET_MODE (dest)))
1121 /* Don't extend the life of a hard register unless it is
1122 user variable (if we have few registers) or it can't
1123 fit into the desired register (meaning something special
1124 is going on).
1125 Also avoid substituting a return register into I3, because
1126 reload can't handle a conflict with constraints of other
1127 inputs. */
1128 || (REGNO (src) < FIRST_PSEUDO_REGISTER
1129 && ! HARD_REGNO_MODE_OK (REGNO (src), GET_MODE (src)))))
1130 return 0;
1131 }
1132 else if (GET_CODE (dest) != CC0)
1133 return 0;
1134
1135 /* Don't substitute for a register intended as a clobberable operand.
1136 Similarly, don't substitute an expression containing a register that
1137 will be clobbered in I3. */
1138 if (GET_CODE (PATTERN (i3)) == PARALLEL)
1139 for (i = XVECLEN (PATTERN (i3), 0) - 1; i >= 0; i--)
1140 if (GET_CODE (XVECEXP (PATTERN (i3), 0, i)) == CLOBBER
1141 && (reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (i3), 0, i), 0),
1142 src)
1143 || rtx_equal_p (XEXP (XVECEXP (PATTERN (i3), 0, i), 0), dest)))
1144 return 0;
1145
1146 /* If INSN contains anything volatile, or is an `asm' (whether volatile
1147 or not), reject, unless nothing volatile comes between it and I3 */
1148
1149 if (GET_CODE (src) == ASM_OPERANDS || volatile_refs_p (src))
1150 {
1151 /* Make sure succ doesn't contain a volatile reference. */
1152 if (succ != 0 && volatile_refs_p (PATTERN (succ)))
1153 return 0;
1154
1155 for (p = NEXT_INSN (insn); p != i3; p = NEXT_INSN (p))
1156 if (INSN_P (p) && p != succ && volatile_refs_p (PATTERN (p)))
1157 return 0;
1158 }
1159
1160 /* If INSN is an asm, and DEST is a hard register, reject, since it has
1161 to be an explicit register variable, and was chosen for a reason. */
1162
1163 if (GET_CODE (src) == ASM_OPERANDS
1164 && GET_CODE (dest) == REG && REGNO (dest) < FIRST_PSEUDO_REGISTER)
1165 return 0;
1166
1167 /* If there are any volatile insns between INSN and I3, reject, because
1168 they might affect machine state. */
1169
1170 for (p = NEXT_INSN (insn); p != i3; p = NEXT_INSN (p))
1171 if (INSN_P (p) && p != succ && volatile_insn_p (PATTERN (p)))
1172 return 0;
1173
1174 /* If INSN or I2 contains an autoincrement or autodecrement,
1175 make sure that register is not used between there and I3,
1176 and not already used in I3 either.
1177 Also insist that I3 not be a jump; if it were one
1178 and the incremented register were spilled, we would lose. */
1179
1180 #ifdef AUTO_INC_DEC
1181 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1182 if (REG_NOTE_KIND (link) == REG_INC
1183 && (GET_CODE (i3) == JUMP_INSN
1184 || reg_used_between_p (XEXP (link, 0), insn, i3)
1185 || reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i3))))
1186 return 0;
1187 #endif
1188
1189 #ifdef HAVE_cc0
1190 /* Don't combine an insn that follows a CC0-setting insn.
1191 An insn that uses CC0 must not be separated from the one that sets it.
1192 We do, however, allow I2 to follow a CC0-setting insn if that insn
1193 is passed as I1; in that case it will be deleted also.
1194 We also allow combining in this case if all the insns are adjacent
1195 because that would leave the two CC0 insns adjacent as well.
1196 It would be more logical to test whether CC0 occurs inside I1 or I2,
1197 but that would be much slower, and this ought to be equivalent. */
1198
1199 p = prev_nonnote_insn (insn);
1200 if (p && p != pred && GET_CODE (p) == INSN && sets_cc0_p (PATTERN (p))
1201 && ! all_adjacent)
1202 return 0;
1203 #endif
1204
1205 /* If we get here, we have passed all the tests and the combination is
1206 to be allowed. */
1207
1208 *pdest = dest;
1209 *psrc = src;
1210
1211 return 1;
1212 }
1213
1214 /* LOC is the location within I3 that contains its pattern or the component
1215 of a PARALLEL of the pattern. We validate that it is valid for combining.
1216
1217 One problem is if I3 modifies its output, as opposed to replacing it
1218 entirely, we can't allow the output to contain I2DEST or I1DEST as doing
1219 so would produce an insn that is not equivalent to the original insns.
1220
1221 Consider:
1222
1223 (set (reg:DI 101) (reg:DI 100))
1224 (set (subreg:SI (reg:DI 101) 0) <foo>)
1225
1226 This is NOT equivalent to:
1227
1228 (parallel [(set (subreg:SI (reg:DI 100) 0) <foo>)
1229 (set (reg:DI 101) (reg:DI 100))])
1230
1231 Not only does this modify 100 (in which case it might still be valid
1232 if 100 were dead in I2), it sets 101 to the ORIGINAL value of 100.
1233
1234 We can also run into a problem if I2 sets a register that I1
1235 uses and I1 gets directly substituted into I3 (not via I2). In that
1236 case, we would be getting the wrong value of I2DEST into I3, so we
1237 must reject the combination. This case occurs when I2 and I1 both
1238 feed into I3, rather than when I1 feeds into I2, which feeds into I3.
1239 If I1_NOT_IN_SRC is nonzero, it means that finding I1 in the source
1240 of a SET must prevent combination from occurring.
1241
1242 Before doing the above check, we first try to expand a field assignment
1243 into a set of logical operations.
1244
1245 If PI3_DEST_KILLED is nonzero, it is a pointer to a location in which
1246 we place a register that is both set and used within I3. If more than one
1247 such register is detected, we fail.
1248
1249 Return 1 if the combination is valid, zero otherwise. */
1250
1251 static int
combinable_i3pat(rtx i3,rtx * loc,rtx i2dest,rtx i1dest,int i1_not_in_src,rtx * pi3dest_killed)1252 combinable_i3pat (rtx i3, rtx *loc, rtx i2dest, rtx i1dest,
1253 int i1_not_in_src, rtx *pi3dest_killed)
1254 {
1255 rtx x = *loc;
1256
1257 if (GET_CODE (x) == SET)
1258 {
1259 rtx set = x ;
1260 rtx dest = SET_DEST (set);
1261 rtx src = SET_SRC (set);
1262 rtx inner_dest = dest;
1263
1264 while (GET_CODE (inner_dest) == STRICT_LOW_PART
1265 || GET_CODE (inner_dest) == SUBREG
1266 || GET_CODE (inner_dest) == ZERO_EXTRACT)
1267 inner_dest = XEXP (inner_dest, 0);
1268
1269 /* Check for the case where I3 modifies its output, as discussed
1270 above. We don't want to prevent pseudos from being combined
1271 into the address of a MEM, so only prevent the combination if
1272 i1 or i2 set the same MEM. */
1273 if ((inner_dest != dest &&
1274 (GET_CODE (inner_dest) != MEM
1275 || rtx_equal_p (i2dest, inner_dest)
1276 || (i1dest && rtx_equal_p (i1dest, inner_dest)))
1277 && (reg_overlap_mentioned_p (i2dest, inner_dest)
1278 || (i1dest && reg_overlap_mentioned_p (i1dest, inner_dest))))
1279
1280 /* This is the same test done in can_combine_p except we can't test
1281 all_adjacent; we don't have to, since this instruction will stay
1282 in place, thus we are not considering increasing the lifetime of
1283 INNER_DEST.
1284
1285 Also, if this insn sets a function argument, combining it with
1286 something that might need a spill could clobber a previous
1287 function argument; the all_adjacent test in can_combine_p also
1288 checks this; here, we do a more specific test for this case. */
1289
1290 || (GET_CODE (inner_dest) == REG
1291 && REGNO (inner_dest) < FIRST_PSEUDO_REGISTER
1292 && (! HARD_REGNO_MODE_OK (REGNO (inner_dest),
1293 GET_MODE (inner_dest))))
1294 || (i1_not_in_src && reg_overlap_mentioned_p (i1dest, src)))
1295 return 0;
1296
1297 /* If DEST is used in I3, it is being killed in this insn,
1298 so record that for later.
1299 Never add REG_DEAD notes for the FRAME_POINTER_REGNUM or the
1300 STACK_POINTER_REGNUM, since these are always considered to be
1301 live. Similarly for ARG_POINTER_REGNUM if it is fixed. */
1302 if (pi3dest_killed && GET_CODE (dest) == REG
1303 && reg_referenced_p (dest, PATTERN (i3))
1304 && REGNO (dest) != FRAME_POINTER_REGNUM
1305 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
1306 && REGNO (dest) != HARD_FRAME_POINTER_REGNUM
1307 #endif
1308 #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM
1309 && (REGNO (dest) != ARG_POINTER_REGNUM
1310 || ! fixed_regs [REGNO (dest)])
1311 #endif
1312 && REGNO (dest) != STACK_POINTER_REGNUM)
1313 {
1314 if (*pi3dest_killed)
1315 return 0;
1316
1317 *pi3dest_killed = dest;
1318 }
1319 }
1320
1321 else if (GET_CODE (x) == PARALLEL)
1322 {
1323 int i;
1324
1325 for (i = 0; i < XVECLEN (x, 0); i++)
1326 if (! combinable_i3pat (i3, &XVECEXP (x, 0, i), i2dest, i1dest,
1327 i1_not_in_src, pi3dest_killed))
1328 return 0;
1329 }
1330
1331 return 1;
1332 }
1333
1334 /* Return 1 if X is an arithmetic expression that contains a multiplication
1335 and division. We don't count multiplications by powers of two here. */
1336
1337 static int
contains_muldiv(rtx x)1338 contains_muldiv (rtx x)
1339 {
1340 switch (GET_CODE (x))
1341 {
1342 case MOD: case DIV: case UMOD: case UDIV:
1343 return 1;
1344
1345 case MULT:
1346 return ! (GET_CODE (XEXP (x, 1)) == CONST_INT
1347 && exact_log2 (INTVAL (XEXP (x, 1))) >= 0);
1348 default:
1349 switch (GET_RTX_CLASS (GET_CODE (x)))
1350 {
1351 case 'c': case '<': case '2':
1352 return contains_muldiv (XEXP (x, 0))
1353 || contains_muldiv (XEXP (x, 1));
1354
1355 case '1':
1356 return contains_muldiv (XEXP (x, 0));
1357
1358 default:
1359 return 0;
1360 }
1361 }
1362 }
1363
1364 /* Determine whether INSN can be used in a combination. Return nonzero if
1365 not. This is used in try_combine to detect early some cases where we
1366 can't perform combinations. */
1367
1368 static int
cant_combine_insn_p(rtx insn)1369 cant_combine_insn_p (rtx insn)
1370 {
1371 rtx set;
1372 rtx src, dest;
1373
1374 /* If this isn't really an insn, we can't do anything.
1375 This can occur when flow deletes an insn that it has merged into an
1376 auto-increment address. */
1377 if (! INSN_P (insn))
1378 return 1;
1379
1380 /* Never combine loads and stores involving hard regs that are likely
1381 to be spilled. The register allocator can usually handle such
1382 reg-reg moves by tying. If we allow the combiner to make
1383 substitutions of likely-spilled regs, we may abort in reload.
1384 As an exception, we allow combinations involving fixed regs; these are
1385 not available to the register allocator so there's no risk involved. */
1386
1387 set = single_set (insn);
1388 if (! set)
1389 return 0;
1390 src = SET_SRC (set);
1391 dest = SET_DEST (set);
1392 if (GET_CODE (src) == SUBREG)
1393 src = SUBREG_REG (src);
1394 if (GET_CODE (dest) == SUBREG)
1395 dest = SUBREG_REG (dest);
1396 if (REG_P (src) && REG_P (dest)
1397 && ((REGNO (src) < FIRST_PSEUDO_REGISTER
1398 && ! fixed_regs[REGNO (src)]
1399 && CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (REGNO (src))))
1400 || (REGNO (dest) < FIRST_PSEUDO_REGISTER
1401 && ! fixed_regs[REGNO (dest)]
1402 && CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (REGNO (dest))))))
1403 return 1;
1404
1405 return 0;
1406 }
1407
1408 /* Adjust INSN after we made a change to its destination.
1409
1410 Changing the destination can invalidate notes that say something about
1411 the results of the insn and a LOG_LINK pointing to the insn. */
1412
1413 static void
adjust_for_new_dest(rtx insn)1414 adjust_for_new_dest (rtx insn)
1415 {
1416 rtx *loc;
1417
1418 /* For notes, be conservative and simply remove them. */
1419 loc = ®_NOTES (insn);
1420 while (*loc)
1421 {
1422 enum reg_note kind = REG_NOTE_KIND (*loc);
1423 if (kind == REG_EQUAL || kind == REG_EQUIV)
1424 *loc = XEXP (*loc, 1);
1425 else
1426 loc = &XEXP (*loc, 1);
1427 }
1428
1429 /* The new insn will have a destination that was previously the destination
1430 of an insn just above it. Call distribute_links to make a LOG_LINK from
1431 the next use of that destination. */
1432 distribute_links (gen_rtx_INSN_LIST (VOIDmode, insn, NULL_RTX));
1433 }
1434
1435 /* Try to combine the insns I1 and I2 into I3.
1436 Here I1 and I2 appear earlier than I3.
1437 I1 can be zero; then we combine just I2 into I3.
1438
1439 If we are combining three insns and the resulting insn is not recognized,
1440 try splitting it into two insns. If that happens, I2 and I3 are retained
1441 and I1 is pseudo-deleted by turning it into a NOTE. Otherwise, I1 and I2
1442 are pseudo-deleted.
1443
1444 Return 0 if the combination does not work. Then nothing is changed.
1445 If we did the combination, return the insn at which combine should
1446 resume scanning.
1447
1448 Set NEW_DIRECT_JUMP_P to a nonzero value if try_combine creates a
1449 new direct jump instruction. */
1450
1451 static rtx
try_combine(rtx i3,rtx i2,rtx i1,int * new_direct_jump_p)1452 try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
1453 {
1454 /* New patterns for I3 and I2, respectively. */
1455 rtx newpat, newi2pat = 0;
1456 int substed_i2 = 0, substed_i1 = 0;
1457 /* Indicates need to preserve SET in I1 or I2 in I3 if it is not dead. */
1458 int added_sets_1, added_sets_2;
1459 /* Total number of SETs to put into I3. */
1460 int total_sets;
1461 /* Nonzero is I2's body now appears in I3. */
1462 int i2_is_used;
1463 /* INSN_CODEs for new I3, new I2, and user of condition code. */
1464 int insn_code_number, i2_code_number = 0, other_code_number = 0;
1465 /* Contains I3 if the destination of I3 is used in its source, which means
1466 that the old life of I3 is being killed. If that usage is placed into
1467 I2 and not in I3, a REG_DEAD note must be made. */
1468 rtx i3dest_killed = 0;
1469 /* SET_DEST and SET_SRC of I2 and I1. */
1470 rtx i2dest, i2src, i1dest = 0, i1src = 0;
1471 /* PATTERN (I2), or a copy of it in certain cases. */
1472 rtx i2pat;
1473 /* Indicates if I2DEST or I1DEST is in I2SRC or I1_SRC. */
1474 int i2dest_in_i2src = 0, i1dest_in_i1src = 0, i2dest_in_i1src = 0;
1475 int i1_feeds_i3 = 0;
1476 /* Notes that must be added to REG_NOTES in I3 and I2. */
1477 rtx new_i3_notes, new_i2_notes;
1478 /* Notes that we substituted I3 into I2 instead of the normal case. */
1479 int i3_subst_into_i2 = 0;
1480 /* Notes that I1, I2 or I3 is a MULT operation. */
1481 int have_mult = 0;
1482
1483 int maxreg;
1484 rtx temp;
1485 rtx link;
1486 int i;
1487
1488 /* Exit early if one of the insns involved can't be used for
1489 combinations. */
1490 if (cant_combine_insn_p (i3)
1491 || cant_combine_insn_p (i2)
1492 || (i1 && cant_combine_insn_p (i1))
1493 /* We also can't do anything if I3 has a
1494 REG_LIBCALL note since we don't want to disrupt the contiguity of a
1495 libcall. */
1496 #if 0
1497 /* ??? This gives worse code, and appears to be unnecessary, since no
1498 pass after flow uses REG_LIBCALL/REG_RETVAL notes. */
1499 || find_reg_note (i3, REG_LIBCALL, NULL_RTX)
1500 #endif
1501 )
1502 return 0;
1503
1504 combine_attempts++;
1505 undobuf.other_insn = 0;
1506
1507 /* Reset the hard register usage information. */
1508 CLEAR_HARD_REG_SET (newpat_used_regs);
1509
1510 /* If I1 and I2 both feed I3, they can be in any order. To simplify the
1511 code below, set I1 to be the earlier of the two insns. */
1512 if (i1 && INSN_CUID (i1) > INSN_CUID (i2))
1513 temp = i1, i1 = i2, i2 = temp;
1514
1515 added_links_insn = 0;
1516
1517 /* First check for one important special-case that the code below will
1518 not handle. Namely, the case where I1 is zero, I2 is a PARALLEL
1519 and I3 is a SET whose SET_SRC is a SET_DEST in I2. In that case,
1520 we may be able to replace that destination with the destination of I3.
1521 This occurs in the common code where we compute both a quotient and
1522 remainder into a structure, in which case we want to do the computation
1523 directly into the structure to avoid register-register copies.
1524
1525 Note that this case handles both multiple sets in I2 and also
1526 cases where I2 has a number of CLOBBER or PARALLELs.
1527
1528 We make very conservative checks below and only try to handle the
1529 most common cases of this. For example, we only handle the case
1530 where I2 and I3 are adjacent to avoid making difficult register
1531 usage tests. */
1532
1533 if (i1 == 0 && GET_CODE (i3) == INSN && GET_CODE (PATTERN (i3)) == SET
1534 && GET_CODE (SET_SRC (PATTERN (i3))) == REG
1535 && REGNO (SET_SRC (PATTERN (i3))) >= FIRST_PSEUDO_REGISTER
1536 && find_reg_note (i3, REG_DEAD, SET_SRC (PATTERN (i3)))
1537 && GET_CODE (PATTERN (i2)) == PARALLEL
1538 && ! side_effects_p (SET_DEST (PATTERN (i3)))
1539 /* If the dest of I3 is a ZERO_EXTRACT or STRICT_LOW_PART, the code
1540 below would need to check what is inside (and reg_overlap_mentioned_p
1541 doesn't support those codes anyway). Don't allow those destinations;
1542 the resulting insn isn't likely to be recognized anyway. */
1543 && GET_CODE (SET_DEST (PATTERN (i3))) != ZERO_EXTRACT
1544 && GET_CODE (SET_DEST (PATTERN (i3))) != STRICT_LOW_PART
1545 && ! reg_overlap_mentioned_p (SET_SRC (PATTERN (i3)),
1546 SET_DEST (PATTERN (i3)))
1547 && next_real_insn (i2) == i3)
1548 {
1549 rtx p2 = PATTERN (i2);
1550
1551 /* Make sure that the destination of I3,
1552 which we are going to substitute into one output of I2,
1553 is not used within another output of I2. We must avoid making this:
1554 (parallel [(set (mem (reg 69)) ...)
1555 (set (reg 69) ...)])
1556 which is not well-defined as to order of actions.
1557 (Besides, reload can't handle output reloads for this.)
1558
1559 The problem can also happen if the dest of I3 is a memory ref,
1560 if another dest in I2 is an indirect memory ref. */
1561 for (i = 0; i < XVECLEN (p2, 0); i++)
1562 if ((GET_CODE (XVECEXP (p2, 0, i)) == SET
1563 || GET_CODE (XVECEXP (p2, 0, i)) == CLOBBER)
1564 && reg_overlap_mentioned_p (SET_DEST (PATTERN (i3)),
1565 SET_DEST (XVECEXP (p2, 0, i))))
1566 break;
1567
1568 if (i == XVECLEN (p2, 0))
1569 for (i = 0; i < XVECLEN (p2, 0); i++)
1570 if ((GET_CODE (XVECEXP (p2, 0, i)) == SET
1571 || GET_CODE (XVECEXP (p2, 0, i)) == CLOBBER)
1572 && SET_DEST (XVECEXP (p2, 0, i)) == SET_SRC (PATTERN (i3)))
1573 {
1574 combine_merges++;
1575
1576 subst_insn = i3;
1577 subst_low_cuid = INSN_CUID (i2);
1578
1579 added_sets_2 = added_sets_1 = 0;
1580 i2dest = SET_SRC (PATTERN (i3));
1581
1582 /* Replace the dest in I2 with our dest and make the resulting
1583 insn the new pattern for I3. Then skip to where we
1584 validate the pattern. Everything was set up above. */
1585 SUBST (SET_DEST (XVECEXP (p2, 0, i)),
1586 SET_DEST (PATTERN (i3)));
1587
1588 newpat = p2;
1589 i3_subst_into_i2 = 1;
1590 goto validate_replacement;
1591 }
1592 }
1593
1594 /* If I2 is setting a double-word pseudo to a constant and I3 is setting
1595 one of those words to another constant, merge them by making a new
1596 constant. */
1597 if (i1 == 0
1598 && (temp = single_set (i2)) != 0
1599 && (GET_CODE (SET_SRC (temp)) == CONST_INT
1600 || GET_CODE (SET_SRC (temp)) == CONST_DOUBLE)
1601 && GET_CODE (SET_DEST (temp)) == REG
1602 && GET_MODE_CLASS (GET_MODE (SET_DEST (temp))) == MODE_INT
1603 && GET_MODE_SIZE (GET_MODE (SET_DEST (temp))) == 2 * UNITS_PER_WORD
1604 && GET_CODE (PATTERN (i3)) == SET
1605 && GET_CODE (SET_DEST (PATTERN (i3))) == SUBREG
1606 && SUBREG_REG (SET_DEST (PATTERN (i3))) == SET_DEST (temp)
1607 && GET_MODE_CLASS (GET_MODE (SET_DEST (PATTERN (i3)))) == MODE_INT
1608 && GET_MODE_SIZE (GET_MODE (SET_DEST (PATTERN (i3)))) == UNITS_PER_WORD
1609 && GET_CODE (SET_SRC (PATTERN (i3))) == CONST_INT)
1610 {
1611 HOST_WIDE_INT lo, hi;
1612
1613 if (GET_CODE (SET_SRC (temp)) == CONST_INT)
1614 lo = INTVAL (SET_SRC (temp)), hi = lo < 0 ? -1 : 0;
1615 else
1616 {
1617 lo = CONST_DOUBLE_LOW (SET_SRC (temp));
1618 hi = CONST_DOUBLE_HIGH (SET_SRC (temp));
1619 }
1620
1621 if (subreg_lowpart_p (SET_DEST (PATTERN (i3))))
1622 {
1623 /* We don't handle the case of the target word being wider
1624 than a host wide int. */
1625 if (HOST_BITS_PER_WIDE_INT < BITS_PER_WORD)
1626 abort ();
1627
1628 lo &= ~(UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (1) - 1);
1629 lo |= (INTVAL (SET_SRC (PATTERN (i3)))
1630 & (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (1) - 1));
1631 }
1632 else if (HOST_BITS_PER_WIDE_INT == BITS_PER_WORD)
1633 hi = INTVAL (SET_SRC (PATTERN (i3)));
1634 else if (HOST_BITS_PER_WIDE_INT >= 2 * BITS_PER_WORD)
1635 {
1636 int sign = -(int) ((unsigned HOST_WIDE_INT) lo
1637 >> (HOST_BITS_PER_WIDE_INT - 1));
1638
1639 lo &= ~ (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD
1640 (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD (1) - 1));
1641 lo |= (UWIDE_SHIFT_LEFT_BY_BITS_PER_WORD
1642 (INTVAL (SET_SRC (PATTERN (i3)))));
1643 if (hi == sign)
1644 hi = lo < 0 ? -1 : 0;
1645 }
1646 else
1647 /* We don't handle the case of the higher word not fitting
1648 entirely in either hi or lo. */
1649 abort ();
1650
1651 combine_merges++;
1652 subst_insn = i3;
1653 subst_low_cuid = INSN_CUID (i2);
1654 added_sets_2 = added_sets_1 = 0;
1655 i2dest = SET_DEST (temp);
1656
1657 SUBST (SET_SRC (temp),
1658 immed_double_const (lo, hi, GET_MODE (SET_DEST (temp))));
1659
1660 newpat = PATTERN (i2);
1661 goto validate_replacement;
1662 }
1663
1664 #ifndef HAVE_cc0
1665 /* If we have no I1 and I2 looks like:
1666 (parallel [(set (reg:CC X) (compare:CC OP (const_int 0)))
1667 (set Y OP)])
1668 make up a dummy I1 that is
1669 (set Y OP)
1670 and change I2 to be
1671 (set (reg:CC X) (compare:CC Y (const_int 0)))
1672
1673 (We can ignore any trailing CLOBBERs.)
1674
1675 This undoes a previous combination and allows us to match a branch-and-
1676 decrement insn. */
1677
1678 if (i1 == 0 && GET_CODE (PATTERN (i2)) == PARALLEL
1679 && XVECLEN (PATTERN (i2), 0) >= 2
1680 && GET_CODE (XVECEXP (PATTERN (i2), 0, 0)) == SET
1681 && (GET_MODE_CLASS (GET_MODE (SET_DEST (XVECEXP (PATTERN (i2), 0, 0))))
1682 == MODE_CC)
1683 && GET_CODE (SET_SRC (XVECEXP (PATTERN (i2), 0, 0))) == COMPARE
1684 && XEXP (SET_SRC (XVECEXP (PATTERN (i2), 0, 0)), 1) == const0_rtx
1685 && GET_CODE (XVECEXP (PATTERN (i2), 0, 1)) == SET
1686 && GET_CODE (SET_DEST (XVECEXP (PATTERN (i2), 0, 1))) == REG
1687 && rtx_equal_p (XEXP (SET_SRC (XVECEXP (PATTERN (i2), 0, 0)), 0),
1688 SET_SRC (XVECEXP (PATTERN (i2), 0, 1))))
1689 {
1690 for (i = XVECLEN (PATTERN (i2), 0) - 1; i >= 2; i--)
1691 if (GET_CODE (XVECEXP (PATTERN (i2), 0, i)) != CLOBBER)
1692 break;
1693
1694 if (i == 1)
1695 {
1696 /* We make I1 with the same INSN_UID as I2. This gives it
1697 the same INSN_CUID for value tracking. Our fake I1 will
1698 never appear in the insn stream so giving it the same INSN_UID
1699 as I2 will not cause a problem. */
1700
1701 i1 = gen_rtx_INSN (VOIDmode, INSN_UID (i2), NULL_RTX, i2,
1702 BLOCK_FOR_INSN (i2), INSN_LOCATOR (i2),
1703 XVECEXP (PATTERN (i2), 0, 1), -1, NULL_RTX,
1704 NULL_RTX);
1705
1706 SUBST (PATTERN (i2), XVECEXP (PATTERN (i2), 0, 0));
1707 SUBST (XEXP (SET_SRC (PATTERN (i2)), 0),
1708 SET_DEST (PATTERN (i1)));
1709 }
1710 }
1711 #endif
1712
1713 /* Verify that I2 and I1 are valid for combining. */
1714 if (! can_combine_p (i2, i3, i1, NULL_RTX, &i2dest, &i2src)
1715 || (i1 && ! can_combine_p (i1, i3, NULL_RTX, i2, &i1dest, &i1src)))
1716 {
1717 undo_all ();
1718 return 0;
1719 }
1720
1721 /* Record whether I2DEST is used in I2SRC and similarly for the other
1722 cases. Knowing this will help in register status updating below. */
1723 i2dest_in_i2src = reg_overlap_mentioned_p (i2dest, i2src);
1724 i1dest_in_i1src = i1 && reg_overlap_mentioned_p (i1dest, i1src);
1725 i2dest_in_i1src = i1 && reg_overlap_mentioned_p (i2dest, i1src);
1726
1727 /* See if I1 directly feeds into I3. It does if I1DEST is not used
1728 in I2SRC. */
1729 i1_feeds_i3 = i1 && ! reg_overlap_mentioned_p (i1dest, i2src);
1730
1731 /* Ensure that I3's pattern can be the destination of combines. */
1732 if (! combinable_i3pat (i3, &PATTERN (i3), i2dest, i1dest,
1733 i1 && i2dest_in_i1src && i1_feeds_i3,
1734 &i3dest_killed))
1735 {
1736 undo_all ();
1737 return 0;
1738 }
1739
1740 /* See if any of the insns is a MULT operation. Unless one is, we will
1741 reject a combination that is, since it must be slower. Be conservative
1742 here. */
1743 if (GET_CODE (i2src) == MULT
1744 || (i1 != 0 && GET_CODE (i1src) == MULT)
1745 || (GET_CODE (PATTERN (i3)) == SET
1746 && GET_CODE (SET_SRC (PATTERN (i3))) == MULT))
1747 have_mult = 1;
1748
1749 /* If I3 has an inc, then give up if I1 or I2 uses the reg that is inc'd.
1750 We used to do this EXCEPT in one case: I3 has a post-inc in an
1751 output operand. However, that exception can give rise to insns like
1752 mov r3,(r3)+
1753 which is a famous insn on the PDP-11 where the value of r3 used as the
1754 source was model-dependent. Avoid this sort of thing. */
1755
1756 #if 0
1757 if (!(GET_CODE (PATTERN (i3)) == SET
1758 && GET_CODE (SET_SRC (PATTERN (i3))) == REG
1759 && GET_CODE (SET_DEST (PATTERN (i3))) == MEM
1760 && (GET_CODE (XEXP (SET_DEST (PATTERN (i3)), 0)) == POST_INC
1761 || GET_CODE (XEXP (SET_DEST (PATTERN (i3)), 0)) == POST_DEC)))
1762 /* It's not the exception. */
1763 #endif
1764 #ifdef AUTO_INC_DEC
1765 for (link = REG_NOTES (i3); link; link = XEXP (link, 1))
1766 if (REG_NOTE_KIND (link) == REG_INC
1767 && (reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i2))
1768 || (i1 != 0
1769 && reg_overlap_mentioned_p (XEXP (link, 0), PATTERN (i1)))))
1770 {
1771 undo_all ();
1772 return 0;
1773 }
1774 #endif
1775
1776 /* See if the SETs in I1 or I2 need to be kept around in the merged
1777 instruction: whenever the value set there is still needed past I3.
1778 For the SETs in I2, this is easy: we see if I2DEST dies or is set in I3.
1779
1780 For the SET in I1, we have two cases: If I1 and I2 independently
1781 feed into I3, the set in I1 needs to be kept around if I1DEST dies
1782 or is set in I3. Otherwise (if I1 feeds I2 which feeds I3), the set
1783 in I1 needs to be kept around unless I1DEST dies or is set in either
1784 I2 or I3. We can distinguish these cases by seeing if I2SRC mentions
1785 I1DEST. If so, we know I1 feeds into I2. */
1786
1787 added_sets_2 = ! dead_or_set_p (i3, i2dest);
1788
1789 added_sets_1
1790 = i1 && ! (i1_feeds_i3 ? dead_or_set_p (i3, i1dest)
1791 : (dead_or_set_p (i3, i1dest) || dead_or_set_p (i2, i1dest)));
1792
1793 /* If the set in I2 needs to be kept around, we must make a copy of
1794 PATTERN (I2), so that when we substitute I1SRC for I1DEST in
1795 PATTERN (I2), we are only substituting for the original I1DEST, not into
1796 an already-substituted copy. This also prevents making self-referential
1797 rtx. If I2 is a PARALLEL, we just need the piece that assigns I2SRC to
1798 I2DEST. */
1799
1800 i2pat = (GET_CODE (PATTERN (i2)) == PARALLEL
1801 ? gen_rtx_SET (VOIDmode, i2dest, i2src)
1802 : PATTERN (i2));
1803
1804 if (added_sets_2)
1805 i2pat = copy_rtx (i2pat);
1806
1807 combine_merges++;
1808
1809 /* Substitute in the latest insn for the regs set by the earlier ones. */
1810
1811 maxreg = max_reg_num ();
1812
1813 subst_insn = i3;
1814
1815 /* It is possible that the source of I2 or I1 may be performing an
1816 unneeded operation, such as a ZERO_EXTEND of something that is known
1817 to have the high part zero. Handle that case by letting subst look at
1818 the innermost one of them.
1819
1820 Another way to do this would be to have a function that tries to
1821 simplify a single insn instead of merging two or more insns. We don't
1822 do this because of the potential of infinite loops and because
1823 of the potential extra memory required. However, doing it the way
1824 we are is a bit of a kludge and doesn't catch all cases.
1825
1826 But only do this if -fexpensive-optimizations since it slows things down
1827 and doesn't usually win. */
1828
1829 if (flag_expensive_optimizations)
1830 {
1831 /* Pass pc_rtx so no substitutions are done, just simplifications.
1832 The cases that we are interested in here do not involve the few
1833 cases were is_replaced is checked. */
1834 if (i1)
1835 {
1836 subst_low_cuid = INSN_CUID (i1);
1837 i1src = subst (i1src, pc_rtx, pc_rtx, 0, 0);
1838 }
1839 else
1840 {
1841 subst_low_cuid = INSN_CUID (i2);
1842 i2src = subst (i2src, pc_rtx, pc_rtx, 0, 0);
1843 }
1844 }
1845
1846 #ifndef HAVE_cc0
1847 /* Many machines that don't use CC0 have insns that can both perform an
1848 arithmetic operation and set the condition code. These operations will
1849 be represented as a PARALLEL with the first element of the vector
1850 being a COMPARE of an arithmetic operation with the constant zero.
1851 The second element of the vector will set some pseudo to the result
1852 of the same arithmetic operation. If we simplify the COMPARE, we won't
1853 match such a pattern and so will generate an extra insn. Here we test
1854 for this case, where both the comparison and the operation result are
1855 needed, and make the PARALLEL by just replacing I2DEST in I3SRC with
1856 I2SRC. Later we will make the PARALLEL that contains I2. */
1857
1858 if (i1 == 0 && added_sets_2 && GET_CODE (PATTERN (i3)) == SET
1859 && GET_CODE (SET_SRC (PATTERN (i3))) == COMPARE
1860 && XEXP (SET_SRC (PATTERN (i3)), 1) == const0_rtx
1861 && rtx_equal_p (XEXP (SET_SRC (PATTERN (i3)), 0), i2dest))
1862 {
1863 #ifdef SELECT_CC_MODE
1864 rtx *cc_use;
1865 enum machine_mode compare_mode;
1866 #endif
1867
1868 newpat = PATTERN (i3);
1869 SUBST (XEXP (SET_SRC (newpat), 0), i2src);
1870
1871 i2_is_used = 1;
1872
1873 #ifdef SELECT_CC_MODE
1874 /* See if a COMPARE with the operand we substituted in should be done
1875 with the mode that is currently being used. If not, do the same
1876 processing we do in `subst' for a SET; namely, if the destination
1877 is used only once, try to replace it with a register of the proper
1878 mode and also replace the COMPARE. */
1879 if (undobuf.other_insn == 0
1880 && (cc_use = find_single_use (SET_DEST (newpat), i3,
1881 &undobuf.other_insn))
1882 && ((compare_mode = SELECT_CC_MODE (GET_CODE (*cc_use),
1883 i2src, const0_rtx))
1884 != GET_MODE (SET_DEST (newpat))))
1885 {
1886 unsigned int regno = REGNO (SET_DEST (newpat));
1887 rtx new_dest = gen_rtx_REG (compare_mode, regno);
1888
1889 if (regno < FIRST_PSEUDO_REGISTER
1890 || (REG_N_SETS (regno) == 1 && ! added_sets_2
1891 && ! REG_USERVAR_P (SET_DEST (newpat))))
1892 {
1893 if (regno >= FIRST_PSEUDO_REGISTER)
1894 SUBST (regno_reg_rtx[regno], new_dest);
1895
1896 SUBST (SET_DEST (newpat), new_dest);
1897 SUBST (XEXP (*cc_use, 0), new_dest);
1898 SUBST (SET_SRC (newpat),
1899 gen_rtx_COMPARE (compare_mode, i2src, const0_rtx));
1900 }
1901 else
1902 undobuf.other_insn = 0;
1903 }
1904 #endif
1905 }
1906 else
1907 #endif
1908 {
1909 n_occurrences = 0; /* `subst' counts here */
1910
1911 /* If I1 feeds into I2 (not into I3) and I1DEST is in I1SRC, we
1912 need to make a unique copy of I2SRC each time we substitute it
1913 to avoid self-referential rtl. */
1914
1915 subst_low_cuid = INSN_CUID (i2);
1916 newpat = subst (PATTERN (i3), i2dest, i2src, 0,
1917 ! i1_feeds_i3 && i1dest_in_i1src);
1918 substed_i2 = 1;
1919
1920 /* Record whether i2's body now appears within i3's body. */
1921 i2_is_used = n_occurrences;
1922 }
1923
1924 /* If we already got a failure, don't try to do more. Otherwise,
1925 try to substitute in I1 if we have it. */
1926
1927 if (i1 && GET_CODE (newpat) != CLOBBER)
1928 {
1929 /* Before we can do this substitution, we must redo the test done
1930 above (see detailed comments there) that ensures that I1DEST
1931 isn't mentioned in any SETs in NEWPAT that are field assignments. */
1932
1933 if (! combinable_i3pat (NULL_RTX, &newpat, i1dest, NULL_RTX,
1934 0, (rtx*) 0))
1935 {
1936 undo_all ();
1937 return 0;
1938 }
1939
1940 n_occurrences = 0;
1941 subst_low_cuid = INSN_CUID (i1);
1942 newpat = subst (newpat, i1dest, i1src, 0, 0);
1943 substed_i1 = 1;
1944 }
1945
1946 /* Fail if an autoincrement side-effect has been duplicated. Be careful
1947 to count all the ways that I2SRC and I1SRC can be used. */
1948 if ((FIND_REG_INC_NOTE (i2, NULL_RTX) != 0
1949 && i2_is_used + added_sets_2 > 1)
1950 || (i1 != 0 && FIND_REG_INC_NOTE (i1, NULL_RTX) != 0
1951 && (n_occurrences + added_sets_1 + (added_sets_2 && ! i1_feeds_i3)
1952 > 1))
1953 /* Fail if we tried to make a new register (we used to abort, but there's
1954 really no reason to). */
1955 || max_reg_num () != maxreg
1956 /* Fail if we couldn't do something and have a CLOBBER. */
1957 || GET_CODE (newpat) == CLOBBER
1958 /* Fail if this new pattern is a MULT and we didn't have one before
1959 at the outer level. */
1960 || (GET_CODE (newpat) == SET && GET_CODE (SET_SRC (newpat)) == MULT
1961 && ! have_mult))
1962 {
1963 undo_all ();
1964 return 0;
1965 }
1966
1967 /* If the actions of the earlier insns must be kept
1968 in addition to substituting them into the latest one,
1969 we must make a new PARALLEL for the latest insn
1970 to hold additional the SETs. */
1971
1972 if (added_sets_1 || added_sets_2)
1973 {
1974 combine_extras++;
1975
1976 if (GET_CODE (newpat) == PARALLEL)
1977 {
1978 rtvec old = XVEC (newpat, 0);
1979 total_sets = XVECLEN (newpat, 0) + added_sets_1 + added_sets_2;
1980 newpat = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (total_sets));
1981 memcpy (XVEC (newpat, 0)->elem, &old->elem[0],
1982 sizeof (old->elem[0]) * old->num_elem);
1983 }
1984 else
1985 {
1986 rtx old = newpat;
1987 total_sets = 1 + added_sets_1 + added_sets_2;
1988 newpat = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (total_sets));
1989 XVECEXP (newpat, 0, 0) = old;
1990 }
1991
1992 if (added_sets_1)
1993 XVECEXP (newpat, 0, --total_sets)
1994 = (GET_CODE (PATTERN (i1)) == PARALLEL
1995 ? gen_rtx_SET (VOIDmode, i1dest, i1src) : PATTERN (i1));
1996
1997 if (added_sets_2)
1998 {
1999 /* If there is no I1, use I2's body as is. We used to also not do
2000 the subst call below if I2 was substituted into I3,
2001 but that could lose a simplification. */
2002 if (i1 == 0)
2003 XVECEXP (newpat, 0, --total_sets) = i2pat;
2004 else
2005 /* See comment where i2pat is assigned. */
2006 XVECEXP (newpat, 0, --total_sets)
2007 = subst (i2pat, i1dest, i1src, 0, 0);
2008 }
2009 }
2010
2011 /* We come here when we are replacing a destination in I2 with the
2012 destination of I3. */
2013 validate_replacement:
2014
2015 /* Note which hard regs this insn has as inputs. */
2016 mark_used_regs_combine (newpat);
2017
2018 /* Is the result of combination a valid instruction? */
2019 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
2020
2021 /* If the result isn't valid, see if it is a PARALLEL of two SETs where
2022 the second SET's destination is a register that is unused and isn't
2023 marked as an instruction that might trap in an EH region. In that case,
2024 we just need the first SET. This can occur when simplifying a divmod
2025 insn. We *must* test for this case here because the code below that
2026 splits two independent SETs doesn't handle this case correctly when it
2027 updates the register status. Also check the case where the first
2028 SET's destination is unused. That would not cause incorrect code, but
2029 does cause an unneeded insn to remain. */
2030
2031 if (insn_code_number < 0 && GET_CODE (newpat) == PARALLEL
2032 && XVECLEN (newpat, 0) == 2
2033 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
2034 && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
2035 && asm_noperands (newpat) < 0)
2036 {
2037 rtx set0 = XVECEXP (newpat, 0, 0);
2038 rtx set1 = XVECEXP (newpat, 0, 1);
2039 rtx note;
2040
2041 if (((GET_CODE (SET_DEST (set1)) == REG
2042 && find_reg_note (i3, REG_UNUSED, SET_DEST (set1)))
2043 || (GET_CODE (SET_DEST (set1)) == SUBREG
2044 && find_reg_note (i3, REG_UNUSED, SUBREG_REG (SET_DEST (set1)))))
2045 && (!(note = find_reg_note (i3, REG_EH_REGION, NULL_RTX))
2046 || INTVAL (XEXP (note, 0)) <= 0)
2047 && ! side_effects_p (SET_SRC (set1)))
2048 {
2049 newpat = set0;
2050 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
2051 }
2052
2053 else if (((GET_CODE (SET_DEST (set0)) == REG
2054 && find_reg_note (i3, REG_UNUSED, SET_DEST (set0)))
2055 || (GET_CODE (SET_DEST (set0)) == SUBREG
2056 && find_reg_note (i3, REG_UNUSED,
2057 SUBREG_REG (SET_DEST (set0)))))
2058 && (!(note = find_reg_note (i3, REG_EH_REGION, NULL_RTX))
2059 || INTVAL (XEXP (note, 0)) <= 0)
2060 && ! side_effects_p (SET_SRC (set0)))
2061 {
2062 newpat = set1;
2063 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
2064
2065 if (insn_code_number >= 0)
2066 {
2067 /* If we will be able to accept this, we have made a
2068 change to the destination of I3. This requires us to
2069 do a few adjustments. */
2070
2071 PATTERN (i3) = newpat;
2072 adjust_for_new_dest (i3);
2073 }
2074 }
2075 }
2076
2077 /* If we were combining three insns and the result is a simple SET
2078 with no ASM_OPERANDS that wasn't recognized, try to split it into two
2079 insns. There are two ways to do this. It can be split using a
2080 machine-specific method (like when you have an addition of a large
2081 constant) or by combine in the function find_split_point. */
2082
2083 if (i1 && insn_code_number < 0 && GET_CODE (newpat) == SET
2084 && asm_noperands (newpat) < 0)
2085 {
2086 rtx m_split, *split;
2087 rtx ni2dest = i2dest;
2088
2089 /* See if the MD file can split NEWPAT. If it can't, see if letting it
2090 use I2DEST as a scratch register will help. In the latter case,
2091 convert I2DEST to the mode of the source of NEWPAT if we can. */
2092
2093 m_split = split_insns (newpat, i3);
2094
2095 /* We can only use I2DEST as a scratch reg if it doesn't overlap any
2096 inputs of NEWPAT. */
2097
2098 /* ??? If I2DEST is not safe, and I1DEST exists, then it would be
2099 possible to try that as a scratch reg. This would require adding
2100 more code to make it work though. */
2101
2102 if (m_split == 0 && ! reg_overlap_mentioned_p (ni2dest, newpat))
2103 {
2104 /* If I2DEST is a hard register or the only use of a pseudo,
2105 we can change its mode. */
2106 if (GET_MODE (SET_DEST (newpat)) != GET_MODE (i2dest)
2107 && GET_MODE (SET_DEST (newpat)) != VOIDmode
2108 && GET_CODE (i2dest) == REG
2109 && (REGNO (i2dest) < FIRST_PSEUDO_REGISTER
2110 || (REG_N_SETS (REGNO (i2dest)) == 1 && ! added_sets_2
2111 && ! REG_USERVAR_P (i2dest))))
2112 ni2dest = gen_rtx_REG (GET_MODE (SET_DEST (newpat)),
2113 REGNO (i2dest));
2114
2115 m_split = split_insns (gen_rtx_PARALLEL
2116 (VOIDmode,
2117 gen_rtvec (2, newpat,
2118 gen_rtx_CLOBBER (VOIDmode,
2119 ni2dest))),
2120 i3);
2121 /* If the split with the mode-changed register didn't work, try
2122 the original register. */
2123 if (! m_split && ni2dest != i2dest)
2124 {
2125 ni2dest = i2dest;
2126 m_split = split_insns (gen_rtx_PARALLEL
2127 (VOIDmode,
2128 gen_rtvec (2, newpat,
2129 gen_rtx_CLOBBER (VOIDmode,
2130 i2dest))),
2131 i3);
2132 }
2133 }
2134
2135 if (m_split && NEXT_INSN (m_split) == NULL_RTX)
2136 {
2137 m_split = PATTERN (m_split);
2138 insn_code_number = recog_for_combine (&m_split, i3, &new_i3_notes);
2139 if (insn_code_number >= 0)
2140 newpat = m_split;
2141 }
2142 else if (m_split && NEXT_INSN (NEXT_INSN (m_split)) == NULL_RTX
2143 && (next_real_insn (i2) == i3
2144 || ! use_crosses_set_p (PATTERN (m_split), INSN_CUID (i2))))
2145 {
2146 rtx i2set, i3set;
2147 rtx newi3pat = PATTERN (NEXT_INSN (m_split));
2148 newi2pat = PATTERN (m_split);
2149
2150 i3set = single_set (NEXT_INSN (m_split));
2151 i2set = single_set (m_split);
2152
2153 /* In case we changed the mode of I2DEST, replace it in the
2154 pseudo-register table here. We can't do it above in case this
2155 code doesn't get executed and we do a split the other way. */
2156
2157 if (REGNO (i2dest) >= FIRST_PSEUDO_REGISTER)
2158 SUBST (regno_reg_rtx[REGNO (i2dest)], ni2dest);
2159
2160 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
2161
2162 /* If I2 or I3 has multiple SETs, we won't know how to track
2163 register status, so don't use these insns. If I2's destination
2164 is used between I2 and I3, we also can't use these insns. */
2165
2166 if (i2_code_number >= 0 && i2set && i3set
2167 && (next_real_insn (i2) == i3
2168 || ! reg_used_between_p (SET_DEST (i2set), i2, i3)))
2169 insn_code_number = recog_for_combine (&newi3pat, i3,
2170 &new_i3_notes);
2171 if (insn_code_number >= 0)
2172 newpat = newi3pat;
2173
2174 /* It is possible that both insns now set the destination of I3.
2175 If so, we must show an extra use of it. */
2176
2177 if (insn_code_number >= 0)
2178 {
2179 rtx new_i3_dest = SET_DEST (i3set);
2180 rtx new_i2_dest = SET_DEST (i2set);
2181
2182 while (GET_CODE (new_i3_dest) == ZERO_EXTRACT
2183 || GET_CODE (new_i3_dest) == STRICT_LOW_PART
2184 || GET_CODE (new_i3_dest) == SUBREG)
2185 new_i3_dest = XEXP (new_i3_dest, 0);
2186
2187 while (GET_CODE (new_i2_dest) == ZERO_EXTRACT
2188 || GET_CODE (new_i2_dest) == STRICT_LOW_PART
2189 || GET_CODE (new_i2_dest) == SUBREG)
2190 new_i2_dest = XEXP (new_i2_dest, 0);
2191
2192 if (GET_CODE (new_i3_dest) == REG
2193 && GET_CODE (new_i2_dest) == REG
2194 && REGNO (new_i3_dest) == REGNO (new_i2_dest))
2195 REG_N_SETS (REGNO (new_i2_dest))++;
2196 }
2197 }
2198
2199 /* If we can split it and use I2DEST, go ahead and see if that
2200 helps things be recognized. Verify that none of the registers
2201 are set between I2 and I3. */
2202 if (insn_code_number < 0 && (split = find_split_point (&newpat, i3)) != 0
2203 #ifdef HAVE_cc0
2204 && GET_CODE (i2dest) == REG
2205 #endif
2206 /* We need I2DEST in the proper mode. If it is a hard register
2207 or the only use of a pseudo, we can change its mode. */
2208 && (GET_MODE (*split) == GET_MODE (i2dest)
2209 || GET_MODE (*split) == VOIDmode
2210 || REGNO (i2dest) < FIRST_PSEUDO_REGISTER
2211 || (REG_N_SETS (REGNO (i2dest)) == 1 && ! added_sets_2
2212 && ! REG_USERVAR_P (i2dest)))
2213 && (next_real_insn (i2) == i3
2214 || ! use_crosses_set_p (*split, INSN_CUID (i2)))
2215 /* We can't overwrite I2DEST if its value is still used by
2216 NEWPAT. */
2217 && ! reg_referenced_p (i2dest, newpat))
2218 {
2219 rtx newdest = i2dest;
2220 enum rtx_code split_code = GET_CODE (*split);
2221 enum machine_mode split_mode = GET_MODE (*split);
2222
2223 /* Get NEWDEST as a register in the proper mode. We have already
2224 validated that we can do this. */
2225 if (GET_MODE (i2dest) != split_mode && split_mode != VOIDmode)
2226 {
2227 newdest = gen_rtx_REG (split_mode, REGNO (i2dest));
2228
2229 if (REGNO (i2dest) >= FIRST_PSEUDO_REGISTER)
2230 SUBST (regno_reg_rtx[REGNO (i2dest)], newdest);
2231 }
2232
2233 /* If *SPLIT is a (mult FOO (const_int pow2)), convert it to
2234 an ASHIFT. This can occur if it was inside a PLUS and hence
2235 appeared to be a memory address. This is a kludge. */
2236 if (split_code == MULT
2237 && GET_CODE (XEXP (*split, 1)) == CONST_INT
2238 && INTVAL (XEXP (*split, 1)) > 0
2239 && (i = exact_log2 (INTVAL (XEXP (*split, 1)))) >= 0)
2240 {
2241 SUBST (*split, gen_rtx_ASHIFT (split_mode,
2242 XEXP (*split, 0), GEN_INT (i)));
2243 /* Update split_code because we may not have a multiply
2244 anymore. */
2245 split_code = GET_CODE (*split);
2246 }
2247
2248 #ifdef INSN_SCHEDULING
2249 /* If *SPLIT is a paradoxical SUBREG, when we split it, it should
2250 be written as a ZERO_EXTEND. */
2251 if (split_code == SUBREG && GET_CODE (SUBREG_REG (*split)) == MEM)
2252 {
2253 #ifdef LOAD_EXTEND_OP
2254 /* Or as a SIGN_EXTEND if LOAD_EXTEND_OP says that that's
2255 what it really is. */
2256 if (LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (*split)))
2257 == SIGN_EXTEND)
2258 SUBST (*split, gen_rtx_SIGN_EXTEND (split_mode,
2259 SUBREG_REG (*split)));
2260 else
2261 #endif
2262 SUBST (*split, gen_rtx_ZERO_EXTEND (split_mode,
2263 SUBREG_REG (*split)));
2264 }
2265 #endif
2266
2267 newi2pat = gen_rtx_SET (VOIDmode, newdest, *split);
2268 SUBST (*split, newdest);
2269 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
2270
2271 /* If the split point was a MULT and we didn't have one before,
2272 don't use one now. */
2273 if (i2_code_number >= 0 && ! (split_code == MULT && ! have_mult))
2274 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
2275 }
2276 }
2277
2278 /* Check for a case where we loaded from memory in a narrow mode and
2279 then sign extended it, but we need both registers. In that case,
2280 we have a PARALLEL with both loads from the same memory location.
2281 We can split this into a load from memory followed by a register-register
2282 copy. This saves at least one insn, more if register allocation can
2283 eliminate the copy.
2284
2285 We cannot do this if the destination of the first assignment is a
2286 condition code register or cc0. We eliminate this case by making sure
2287 the SET_DEST and SET_SRC have the same mode.
2288
2289 We cannot do this if the destination of the second assignment is
2290 a register that we have already assumed is zero-extended. Similarly
2291 for a SUBREG of such a register. */
2292
2293 else if (i1 && insn_code_number < 0 && asm_noperands (newpat) < 0
2294 && GET_CODE (newpat) == PARALLEL
2295 && XVECLEN (newpat, 0) == 2
2296 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
2297 && GET_CODE (SET_SRC (XVECEXP (newpat, 0, 0))) == SIGN_EXTEND
2298 && (GET_MODE (SET_DEST (XVECEXP (newpat, 0, 0)))
2299 == GET_MODE (SET_SRC (XVECEXP (newpat, 0, 0))))
2300 && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
2301 && rtx_equal_p (SET_SRC (XVECEXP (newpat, 0, 1)),
2302 XEXP (SET_SRC (XVECEXP (newpat, 0, 0)), 0))
2303 && ! use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)),
2304 INSN_CUID (i2))
2305 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT
2306 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART
2307 && ! (temp = SET_DEST (XVECEXP (newpat, 0, 1)),
2308 (GET_CODE (temp) == REG
2309 && reg_nonzero_bits[REGNO (temp)] != 0
2310 && GET_MODE_BITSIZE (GET_MODE (temp)) < BITS_PER_WORD
2311 && GET_MODE_BITSIZE (GET_MODE (temp)) < HOST_BITS_PER_INT
2312 && (reg_nonzero_bits[REGNO (temp)]
2313 != GET_MODE_MASK (word_mode))))
2314 && ! (GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) == SUBREG
2315 && (temp = SUBREG_REG (SET_DEST (XVECEXP (newpat, 0, 1))),
2316 (GET_CODE (temp) == REG
2317 && reg_nonzero_bits[REGNO (temp)] != 0
2318 && GET_MODE_BITSIZE (GET_MODE (temp)) < BITS_PER_WORD
2319 && GET_MODE_BITSIZE (GET_MODE (temp)) < HOST_BITS_PER_INT
2320 && (reg_nonzero_bits[REGNO (temp)]
2321 != GET_MODE_MASK (word_mode)))))
2322 && ! reg_overlap_mentioned_p (SET_DEST (XVECEXP (newpat, 0, 1)),
2323 SET_SRC (XVECEXP (newpat, 0, 1)))
2324 && ! find_reg_note (i3, REG_UNUSED,
2325 SET_DEST (XVECEXP (newpat, 0, 0))))
2326 {
2327 rtx ni2dest;
2328
2329 newi2pat = XVECEXP (newpat, 0, 0);
2330 ni2dest = SET_DEST (XVECEXP (newpat, 0, 0));
2331 newpat = XVECEXP (newpat, 0, 1);
2332 SUBST (SET_SRC (newpat),
2333 gen_lowpart_for_combine (GET_MODE (SET_SRC (newpat)), ni2dest));
2334 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
2335
2336 if (i2_code_number >= 0)
2337 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
2338
2339 if (insn_code_number >= 0)
2340 {
2341 rtx insn;
2342 rtx link;
2343
2344 /* If we will be able to accept this, we have made a change to the
2345 destination of I3. This requires us to do a few adjustments. */
2346 PATTERN (i3) = newpat;
2347 adjust_for_new_dest (i3);
2348
2349 /* I3 now uses what used to be its destination and which is
2350 now I2's destination. That means we need a LOG_LINK from
2351 I3 to I2. But we used to have one, so we still will.
2352
2353 However, some later insn might be using I2's dest and have
2354 a LOG_LINK pointing at I3. We must remove this link.
2355 The simplest way to remove the link is to point it at I1,
2356 which we know will be a NOTE. */
2357
2358 for (insn = NEXT_INSN (i3);
2359 insn && (this_basic_block->next_bb == EXIT_BLOCK_PTR
2360 || insn != BB_HEAD (this_basic_block->next_bb));
2361 insn = NEXT_INSN (insn))
2362 {
2363 if (INSN_P (insn) && reg_referenced_p (ni2dest, PATTERN (insn)))
2364 {
2365 for (link = LOG_LINKS (insn); link;
2366 link = XEXP (link, 1))
2367 if (XEXP (link, 0) == i3)
2368 XEXP (link, 0) = i1;
2369
2370 break;
2371 }
2372 }
2373 }
2374 }
2375
2376 /* Similarly, check for a case where we have a PARALLEL of two independent
2377 SETs but we started with three insns. In this case, we can do the sets
2378 as two separate insns. This case occurs when some SET allows two
2379 other insns to combine, but the destination of that SET is still live. */
2380
2381 else if (i1 && insn_code_number < 0 && asm_noperands (newpat) < 0
2382 && GET_CODE (newpat) == PARALLEL
2383 && XVECLEN (newpat, 0) == 2
2384 && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
2385 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != ZERO_EXTRACT
2386 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != STRICT_LOW_PART
2387 && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
2388 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT
2389 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART
2390 && ! use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)),
2391 INSN_CUID (i2))
2392 /* Don't pass sets with (USE (MEM ...)) dests to the following. */
2393 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != USE
2394 && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != USE
2395 && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 1)),
2396 XVECEXP (newpat, 0, 0))
2397 && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 0)),
2398 XVECEXP (newpat, 0, 1))
2399 && ! (contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 0)))
2400 && contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 1)))))
2401 {
2402 /* Normally, it doesn't matter which of the two is done first,
2403 but it does if one references cc0. In that case, it has to
2404 be first. */
2405 #ifdef HAVE_cc0
2406 if (reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 0)))
2407 {
2408 newi2pat = XVECEXP (newpat, 0, 0);
2409 newpat = XVECEXP (newpat, 0, 1);
2410 }
2411 else
2412 #endif
2413 {
2414 newi2pat = XVECEXP (newpat, 0, 1);
2415 newpat = XVECEXP (newpat, 0, 0);
2416 }
2417
2418 i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
2419
2420 if (i2_code_number >= 0)
2421 insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
2422 }
2423
2424 /* If it still isn't recognized, fail and change things back the way they
2425 were. */
2426 if ((insn_code_number < 0
2427 /* Is the result a reasonable ASM_OPERANDS? */
2428 && (! check_asm_operands (newpat) || added_sets_1 || added_sets_2)))
2429 {
2430 undo_all ();
2431 return 0;
2432 }
2433
2434 /* If we had to change another insn, make sure it is valid also. */
2435 if (undobuf.other_insn)
2436 {
2437 rtx other_pat = PATTERN (undobuf.other_insn);
2438 rtx new_other_notes;
2439 rtx note, next;
2440
2441 CLEAR_HARD_REG_SET (newpat_used_regs);
2442
2443 other_code_number = recog_for_combine (&other_pat, undobuf.other_insn,
2444 &new_other_notes);
2445
2446 if (other_code_number < 0 && ! check_asm_operands (other_pat))
2447 {
2448 undo_all ();
2449 return 0;
2450 }
2451
2452 PATTERN (undobuf.other_insn) = other_pat;
2453
2454 /* If any of the notes in OTHER_INSN were REG_UNUSED, ensure that they
2455 are still valid. Then add any non-duplicate notes added by
2456 recog_for_combine. */
2457 for (note = REG_NOTES (undobuf.other_insn); note; note = next)
2458 {
2459 next = XEXP (note, 1);
2460
2461 if (REG_NOTE_KIND (note) == REG_UNUSED
2462 && ! reg_set_p (XEXP (note, 0), PATTERN (undobuf.other_insn)))
2463 {
2464 if (GET_CODE (XEXP (note, 0)) == REG)
2465 REG_N_DEATHS (REGNO (XEXP (note, 0)))--;
2466
2467 remove_note (undobuf.other_insn, note);
2468 }
2469 }
2470
2471 for (note = new_other_notes; note; note = XEXP (note, 1))
2472 if (GET_CODE (XEXP (note, 0)) == REG)
2473 REG_N_DEATHS (REGNO (XEXP (note, 0)))++;
2474
2475 distribute_notes (new_other_notes, undobuf.other_insn,
2476 undobuf.other_insn, NULL_RTX);
2477 }
2478 #ifdef HAVE_cc0
2479 /* If I2 is the setter CC0 and I3 is the user CC0 then check whether
2480 they are adjacent to each other or not. */
2481 {
2482 rtx p = prev_nonnote_insn (i3);
2483 if (p && p != i2 && GET_CODE (p) == INSN && newi2pat
2484 && sets_cc0_p (newi2pat))
2485 {
2486 undo_all ();
2487 return 0;
2488 }
2489 }
2490 #endif
2491
2492 /* We now know that we can do this combination. Merge the insns and
2493 update the status of registers and LOG_LINKS. */
2494
2495 {
2496 rtx i3notes, i2notes, i1notes = 0;
2497 rtx i3links, i2links, i1links = 0;
2498 rtx midnotes = 0;
2499 unsigned int regno;
2500
2501 /* Get the old REG_NOTES and LOG_LINKS from all our insns and
2502 clear them. */
2503 i3notes = REG_NOTES (i3), i3links = LOG_LINKS (i3);
2504 i2notes = REG_NOTES (i2), i2links = LOG_LINKS (i2);
2505 if (i1)
2506 i1notes = REG_NOTES (i1), i1links = LOG_LINKS (i1);
2507
2508 /* Ensure that we do not have something that should not be shared but
2509 occurs multiple times in the new insns. Check this by first
2510 resetting all the `used' flags and then copying anything is shared. */
2511
2512 reset_used_flags (i3notes);
2513 reset_used_flags (i2notes);
2514 reset_used_flags (i1notes);
2515 reset_used_flags (newpat);
2516 reset_used_flags (newi2pat);
2517 if (undobuf.other_insn)
2518 reset_used_flags (PATTERN (undobuf.other_insn));
2519
2520 i3notes = copy_rtx_if_shared (i3notes);
2521 i2notes = copy_rtx_if_shared (i2notes);
2522 i1notes = copy_rtx_if_shared (i1notes);
2523 newpat = copy_rtx_if_shared (newpat);
2524 newi2pat = copy_rtx_if_shared (newi2pat);
2525 if (undobuf.other_insn)
2526 reset_used_flags (PATTERN (undobuf.other_insn));
2527
2528 INSN_CODE (i3) = insn_code_number;
2529 PATTERN (i3) = newpat;
2530
2531 if (GET_CODE (i3) == CALL_INSN && CALL_INSN_FUNCTION_USAGE (i3))
2532 {
2533 rtx call_usage = CALL_INSN_FUNCTION_USAGE (i3);
2534
2535 reset_used_flags (call_usage);
2536 call_usage = copy_rtx (call_usage);
2537
2538 if (substed_i2)
2539 replace_rtx (call_usage, i2dest, i2src);
2540
2541 if (substed_i1)
2542 replace_rtx (call_usage, i1dest, i1src);
2543
2544 CALL_INSN_FUNCTION_USAGE (i3) = call_usage;
2545 }
2546
2547 if (undobuf.other_insn)
2548 INSN_CODE (undobuf.other_insn) = other_code_number;
2549
2550 /* We had one special case above where I2 had more than one set and
2551 we replaced a destination of one of those sets with the destination
2552 of I3. In that case, we have to update LOG_LINKS of insns later
2553 in this basic block. Note that this (expensive) case is rare.
2554
2555 Also, in this case, we must pretend that all REG_NOTEs for I2
2556 actually came from I3, so that REG_UNUSED notes from I2 will be
2557 properly handled. */
2558
2559 if (i3_subst_into_i2)
2560 {
2561 for (i = 0; i < XVECLEN (PATTERN (i2), 0); i++)
2562 if (GET_CODE (XVECEXP (PATTERN (i2), 0, i)) != USE
2563 && GET_CODE (SET_DEST (XVECEXP (PATTERN (i2), 0, i))) == REG
2564 && SET_DEST (XVECEXP (PATTERN (i2), 0, i)) != i2dest
2565 && ! find_reg_note (i2, REG_UNUSED,
2566 SET_DEST (XVECEXP (PATTERN (i2), 0, i))))
2567 for (temp = NEXT_INSN (i2);
2568 temp && (this_basic_block->next_bb == EXIT_BLOCK_PTR
2569 || BB_HEAD (this_basic_block) != temp);
2570 temp = NEXT_INSN (temp))
2571 if (temp != i3 && INSN_P (temp))
2572 for (link = LOG_LINKS (temp); link; link = XEXP (link, 1))
2573 if (XEXP (link, 0) == i2)
2574 XEXP (link, 0) = i3;
2575
2576 if (i3notes)
2577 {
2578 rtx link = i3notes;
2579 while (XEXP (link, 1))
2580 link = XEXP (link, 1);
2581 XEXP (link, 1) = i2notes;
2582 }
2583 else
2584 i3notes = i2notes;
2585 i2notes = 0;
2586 }
2587
2588 LOG_LINKS (i3) = 0;
2589 REG_NOTES (i3) = 0;
2590 LOG_LINKS (i2) = 0;
2591 REG_NOTES (i2) = 0;
2592
2593 if (newi2pat)
2594 {
2595 INSN_CODE (i2) = i2_code_number;
2596 PATTERN (i2) = newi2pat;
2597 }
2598 else
2599 {
2600 PUT_CODE (i2, NOTE);
2601 NOTE_LINE_NUMBER (i2) = NOTE_INSN_DELETED;
2602 NOTE_SOURCE_FILE (i2) = 0;
2603 }
2604
2605 if (i1)
2606 {
2607 LOG_LINKS (i1) = 0;
2608 REG_NOTES (i1) = 0;
2609 PUT_CODE (i1, NOTE);
2610 NOTE_LINE_NUMBER (i1) = NOTE_INSN_DELETED;
2611 NOTE_SOURCE_FILE (i1) = 0;
2612 }
2613
2614 /* Get death notes for everything that is now used in either I3 or
2615 I2 and used to die in a previous insn. If we built two new
2616 patterns, move from I1 to I2 then I2 to I3 so that we get the
2617 proper movement on registers that I2 modifies. */
2618
2619 if (newi2pat)
2620 {
2621 move_deaths (newi2pat, NULL_RTX, INSN_CUID (i1), i2, &midnotes);
2622 move_deaths (newpat, newi2pat, INSN_CUID (i1), i3, &midnotes);
2623 }
2624 else
2625 move_deaths (newpat, NULL_RTX, i1 ? INSN_CUID (i1) : INSN_CUID (i2),
2626 i3, &midnotes);
2627
2628 /* Distribute all the LOG_LINKS and REG_NOTES from I1, I2, and I3. */
2629 if (i3notes)
2630 distribute_notes (i3notes, i3, i3, newi2pat ? i2 : NULL_RTX);
2631 if (i2notes)
2632 distribute_notes (i2notes, i2, i3, newi2pat ? i2 : NULL_RTX);
2633 if (i1notes)
2634 distribute_notes (i1notes, i1, i3, newi2pat ? i2 : NULL_RTX);
2635 if (midnotes)
2636 distribute_notes (midnotes, NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
2637
2638 /* Distribute any notes added to I2 or I3 by recog_for_combine. We
2639 know these are REG_UNUSED and want them to go to the desired insn,
2640 so we always pass it as i3. We have not counted the notes in
2641 reg_n_deaths yet, so we need to do so now. */
2642
2643 if (newi2pat && new_i2_notes)
2644 {
2645 for (temp = new_i2_notes; temp; temp = XEXP (temp, 1))
2646 if (GET_CODE (XEXP (temp, 0)) == REG)
2647 REG_N_DEATHS (REGNO (XEXP (temp, 0)))++;
2648
2649 distribute_notes (new_i2_notes, i2, i2, NULL_RTX);
2650 }
2651
2652 if (new_i3_notes)
2653 {
2654 for (temp = new_i3_notes; temp; temp = XEXP (temp, 1))
2655 if (GET_CODE (XEXP (temp, 0)) == REG)
2656 REG_N_DEATHS (REGNO (XEXP (temp, 0)))++;
2657
2658 distribute_notes (new_i3_notes, i3, i3, NULL_RTX);
2659 }
2660
2661 /* If I3DEST was used in I3SRC, it really died in I3. We may need to
2662 put a REG_DEAD note for it somewhere. If NEWI2PAT exists and sets
2663 I3DEST, the death must be somewhere before I2, not I3. If we passed I3
2664 in that case, it might delete I2. Similarly for I2 and I1.
2665 Show an additional death due to the REG_DEAD note we make here. If
2666 we discard it in distribute_notes, we will decrement it again. */
2667
2668 if (i3dest_killed)
2669 {
2670 if (GET_CODE (i3dest_killed) == REG)
2671 REG_N_DEATHS (REGNO (i3dest_killed))++;
2672
2673 if (newi2pat && reg_set_p (i3dest_killed, newi2pat))
2674 distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i3dest_killed,
2675 NULL_RTX),
2676 NULL_RTX, i2, NULL_RTX);
2677 else
2678 distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i3dest_killed,
2679 NULL_RTX),
2680 NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
2681 }
2682
2683 if (i2dest_in_i2src)
2684 {
2685 if (GET_CODE (i2dest) == REG)
2686 REG_N_DEATHS (REGNO (i2dest))++;
2687
2688 if (newi2pat && reg_set_p (i2dest, newi2pat))
2689 distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i2dest, NULL_RTX),
2690 NULL_RTX, i2, NULL_RTX);
2691 else
2692 distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i2dest, NULL_RTX),
2693 NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
2694 }
2695
2696 if (i1dest_in_i1src)
2697 {
2698 if (GET_CODE (i1dest) == REG)
2699 REG_N_DEATHS (REGNO (i1dest))++;
2700
2701 if (newi2pat && reg_set_p (i1dest, newi2pat))
2702 distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i1dest, NULL_RTX),
2703 NULL_RTX, i2, NULL_RTX);
2704 else
2705 distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i1dest, NULL_RTX),
2706 NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
2707 }
2708
2709 distribute_links (i3links);
2710 distribute_links (i2links);
2711 distribute_links (i1links);
2712
2713 if (GET_CODE (i2dest) == REG)
2714 {
2715 rtx link;
2716 rtx i2_insn = 0, i2_val = 0, set;
2717
2718 /* The insn that used to set this register doesn't exist, and
2719 this life of the register may not exist either. See if one of
2720 I3's links points to an insn that sets I2DEST. If it does,
2721 that is now the last known value for I2DEST. If we don't update
2722 this and I2 set the register to a value that depended on its old
2723 contents, we will get confused. If this insn is used, thing
2724 will be set correctly in combine_instructions. */
2725
2726 for (link = LOG_LINKS (i3); link; link = XEXP (link, 1))
2727 if ((set = single_set (XEXP (link, 0))) != 0
2728 && rtx_equal_p (i2dest, SET_DEST (set)))
2729 i2_insn = XEXP (link, 0), i2_val = SET_SRC (set);
2730
2731 record_value_for_reg (i2dest, i2_insn, i2_val);
2732
2733 /* If the reg formerly set in I2 died only once and that was in I3,
2734 zero its use count so it won't make `reload' do any work. */
2735 if (! added_sets_2
2736 && (newi2pat == 0 || ! reg_mentioned_p (i2dest, newi2pat))
2737 && ! i2dest_in_i2src)
2738 {
2739 regno = REGNO (i2dest);
2740 REG_N_SETS (regno)--;
2741 }
2742 }
2743
2744 if (i1 && GET_CODE (i1dest) == REG)
2745 {
2746 rtx link;
2747 rtx i1_insn = 0, i1_val = 0, set;
2748
2749 for (link = LOG_LINKS (i3); link; link = XEXP (link, 1))
2750 if ((set = single_set (XEXP (link, 0))) != 0
2751 && rtx_equal_p (i1dest, SET_DEST (set)))
2752 i1_insn = XEXP (link, 0), i1_val = SET_SRC (set);
2753
2754 record_value_for_reg (i1dest, i1_insn, i1_val);
2755
2756 regno = REGNO (i1dest);
2757 if (! added_sets_1 && ! i1dest_in_i1src)
2758 REG_N_SETS (regno)--;
2759 }
2760
2761 /* Update reg_nonzero_bits et al for any changes that may have been made
2762 to this insn. The order of set_nonzero_bits_and_sign_copies() is
2763 important. Because newi2pat can affect nonzero_bits of newpat */
2764 if (newi2pat)
2765 note_stores (newi2pat, set_nonzero_bits_and_sign_copies, NULL);
2766 note_stores (newpat, set_nonzero_bits_and_sign_copies, NULL);
2767
2768 /* Set new_direct_jump_p if a new return or simple jump instruction
2769 has been created.
2770
2771 If I3 is now an unconditional jump, ensure that it has a
2772 BARRIER following it since it may have initially been a
2773 conditional jump. It may also be the last nonnote insn. */
2774
2775 if (returnjump_p (i3) || any_uncondjump_p (i3))
2776 {
2777 *new_direct_jump_p = 1;
2778 mark_jump_label (PATTERN (i3), i3, 0);
2779
2780 if ((temp = next_nonnote_insn (i3)) == NULL_RTX
2781 || GET_CODE (temp) != BARRIER)
2782 emit_barrier_after (i3);
2783 }
2784
2785 if (undobuf.other_insn != NULL_RTX
2786 && (returnjump_p (undobuf.other_insn)
2787 || any_uncondjump_p (undobuf.other_insn)))
2788 {
2789 *new_direct_jump_p = 1;
2790
2791 if ((temp = next_nonnote_insn (undobuf.other_insn)) == NULL_RTX
2792 || GET_CODE (temp) != BARRIER)
2793 emit_barrier_after (undobuf.other_insn);
2794 }
2795
2796 /* An NOOP jump does not need barrier, but it does need cleaning up
2797 of CFG. */
2798 if (GET_CODE (newpat) == SET
2799 && SET_SRC (newpat) == pc_rtx
2800 && SET_DEST (newpat) == pc_rtx)
2801 *new_direct_jump_p = 1;
2802 }
2803
2804 combine_successes++;
2805 undo_commit ();
2806
2807 if (added_links_insn
2808 && (newi2pat == 0 || INSN_CUID (added_links_insn) < INSN_CUID (i2))
2809 && INSN_CUID (added_links_insn) < INSN_CUID (i3))
2810 return added_links_insn;
2811 else
2812 return newi2pat ? i2 : i3;
2813 }
2814
2815 /* Undo all the modifications recorded in undobuf. */
2816
2817 static void
undo_all(void)2818 undo_all (void)
2819 {
2820 struct undo *undo, *next;
2821
2822 for (undo = undobuf.undos; undo; undo = next)
2823 {
2824 next = undo->next;
2825 if (undo->is_int)
2826 *undo->where.i = undo->old_contents.i;
2827 else
2828 *undo->where.r = undo->old_contents.r;
2829
2830 undo->next = undobuf.frees;
2831 undobuf.frees = undo;
2832 }
2833
2834 undobuf.undos = 0;
2835 }
2836
2837 /* We've committed to accepting the changes we made. Move all
2838 of the undos to the free list. */
2839
2840 static void
undo_commit(void)2841 undo_commit (void)
2842 {
2843 struct undo *undo, *next;
2844
2845 for (undo = undobuf.undos; undo; undo = next)
2846 {
2847 next = undo->next;
2848 undo->next = undobuf.frees;
2849 undobuf.frees = undo;
2850 }
2851 undobuf.undos = 0;
2852 }
2853
2854
2855 /* Find the innermost point within the rtx at LOC, possibly LOC itself,
2856 where we have an arithmetic expression and return that point. LOC will
2857 be inside INSN.
2858
2859 try_combine will call this function to see if an insn can be split into
2860 two insns. */
2861
2862 static rtx *
find_split_point(rtx * loc,rtx insn)2863 find_split_point (rtx *loc, rtx insn)
2864 {
2865 rtx x = *loc;
2866 enum rtx_code code = GET_CODE (x);
2867 rtx *split;
2868 unsigned HOST_WIDE_INT len = 0;
2869 HOST_WIDE_INT pos = 0;
2870 int unsignedp = 0;
2871 rtx inner = NULL_RTX;
2872
2873 /* First special-case some codes. */
2874 switch (code)
2875 {
2876 case SUBREG:
2877 #ifdef INSN_SCHEDULING
2878 /* If we are making a paradoxical SUBREG invalid, it becomes a split
2879 point. */
2880 if (GET_CODE (SUBREG_REG (x)) == MEM)
2881 return loc;
2882 #endif
2883 return find_split_point (&SUBREG_REG (x), insn);
2884
2885 case MEM:
2886 #ifdef HAVE_lo_sum
2887 /* If we have (mem (const ..)) or (mem (symbol_ref ...)), split it
2888 using LO_SUM and HIGH. */
2889 if (GET_CODE (XEXP (x, 0)) == CONST
2890 || GET_CODE (XEXP (x, 0)) == SYMBOL_REF)
2891 {
2892 SUBST (XEXP (x, 0),
2893 gen_rtx_LO_SUM (Pmode,
2894 gen_rtx_HIGH (Pmode, XEXP (x, 0)),
2895 XEXP (x, 0)));
2896 return &XEXP (XEXP (x, 0), 0);
2897 }
2898 #endif
2899
2900 /* If we have a PLUS whose second operand is a constant and the
2901 address is not valid, perhaps will can split it up using
2902 the machine-specific way to split large constants. We use
2903 the first pseudo-reg (one of the virtual regs) as a placeholder;
2904 it will not remain in the result. */
2905 if (GET_CODE (XEXP (x, 0)) == PLUS
2906 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2907 && ! memory_address_p (GET_MODE (x), XEXP (x, 0)))
2908 {
2909 rtx reg = regno_reg_rtx[FIRST_PSEUDO_REGISTER];
2910 rtx seq = split_insns (gen_rtx_SET (VOIDmode, reg, XEXP (x, 0)),
2911 subst_insn);
2912
2913 /* This should have produced two insns, each of which sets our
2914 placeholder. If the source of the second is a valid address,
2915 we can make put both sources together and make a split point
2916 in the middle. */
2917
2918 if (seq
2919 && NEXT_INSN (seq) != NULL_RTX
2920 && NEXT_INSN (NEXT_INSN (seq)) == NULL_RTX
2921 && GET_CODE (seq) == INSN
2922 && GET_CODE (PATTERN (seq)) == SET
2923 && SET_DEST (PATTERN (seq)) == reg
2924 && ! reg_mentioned_p (reg,
2925 SET_SRC (PATTERN (seq)))
2926 && GET_CODE (NEXT_INSN (seq)) == INSN
2927 && GET_CODE (PATTERN (NEXT_INSN (seq))) == SET
2928 && SET_DEST (PATTERN (NEXT_INSN (seq))) == reg
2929 && memory_address_p (GET_MODE (x),
2930 SET_SRC (PATTERN (NEXT_INSN (seq)))))
2931 {
2932 rtx src1 = SET_SRC (PATTERN (seq));
2933 rtx src2 = SET_SRC (PATTERN (NEXT_INSN (seq)));
2934
2935 /* Replace the placeholder in SRC2 with SRC1. If we can
2936 find where in SRC2 it was placed, that can become our
2937 split point and we can replace this address with SRC2.
2938 Just try two obvious places. */
2939
2940 src2 = replace_rtx (src2, reg, src1);
2941 split = 0;
2942 if (XEXP (src2, 0) == src1)
2943 split = &XEXP (src2, 0);
2944 else if (GET_RTX_FORMAT (GET_CODE (XEXP (src2, 0)))[0] == 'e'
2945 && XEXP (XEXP (src2, 0), 0) == src1)
2946 split = &XEXP (XEXP (src2, 0), 0);
2947
2948 if (split)
2949 {
2950 SUBST (XEXP (x, 0), src2);
2951 return split;
2952 }
2953 }
2954
2955 /* If that didn't work, perhaps the first operand is complex and
2956 needs to be computed separately, so make a split point there.
2957 This will occur on machines that just support REG + CONST
2958 and have a constant moved through some previous computation. */
2959
2960 else if (GET_RTX_CLASS (GET_CODE (XEXP (XEXP (x, 0), 0))) != 'o'
2961 && ! (GET_CODE (XEXP (XEXP (x, 0), 0)) == SUBREG
2962 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (XEXP (x, 0), 0))))
2963 == 'o')))
2964 return &XEXP (XEXP (x, 0), 0);
2965 }
2966 break;
2967
2968 case SET:
2969 #ifdef HAVE_cc0
2970 /* If SET_DEST is CC0 and SET_SRC is not an operand, a COMPARE, or a
2971 ZERO_EXTRACT, the most likely reason why this doesn't match is that
2972 we need to put the operand into a register. So split at that
2973 point. */
2974
2975 if (SET_DEST (x) == cc0_rtx
2976 && GET_CODE (SET_SRC (x)) != COMPARE
2977 && GET_CODE (SET_SRC (x)) != ZERO_EXTRACT
2978 && GET_RTX_CLASS (GET_CODE (SET_SRC (x))) != 'o'
2979 && ! (GET_CODE (SET_SRC (x)) == SUBREG
2980 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (SET_SRC (x)))) == 'o'))
2981 return &SET_SRC (x);
2982 #endif
2983
2984 /* See if we can split SET_SRC as it stands. */
2985 split = find_split_point (&SET_SRC (x), insn);
2986 if (split && split != &SET_SRC (x))
2987 return split;
2988
2989 /* See if we can split SET_DEST as it stands. */
2990 split = find_split_point (&SET_DEST (x), insn);
2991 if (split && split != &SET_DEST (x))
2992 return split;
2993
2994 /* See if this is a bitfield assignment with everything constant. If
2995 so, this is an IOR of an AND, so split it into that. */
2996 if (GET_CODE (SET_DEST (x)) == ZERO_EXTRACT
2997 && (GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0)))
2998 <= HOST_BITS_PER_WIDE_INT)
2999 && GET_CODE (XEXP (SET_DEST (x), 1)) == CONST_INT
3000 && GET_CODE (XEXP (SET_DEST (x), 2)) == CONST_INT
3001 && GET_CODE (SET_SRC (x)) == CONST_INT
3002 && ((INTVAL (XEXP (SET_DEST (x), 1))
3003 + INTVAL (XEXP (SET_DEST (x), 2)))
3004 <= GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0))))
3005 && ! side_effects_p (XEXP (SET_DEST (x), 0)))
3006 {
3007 HOST_WIDE_INT pos = INTVAL (XEXP (SET_DEST (x), 2));
3008 unsigned HOST_WIDE_INT len = INTVAL (XEXP (SET_DEST (x), 1));
3009 unsigned HOST_WIDE_INT src = INTVAL (SET_SRC (x));
3010 rtx dest = XEXP (SET_DEST (x), 0);
3011 enum machine_mode mode = GET_MODE (dest);
3012 unsigned HOST_WIDE_INT mask = ((HOST_WIDE_INT) 1 << len) - 1;
3013
3014 if (BITS_BIG_ENDIAN)
3015 pos = GET_MODE_BITSIZE (mode) - len - pos;
3016
3017 if (src == mask)
3018 SUBST (SET_SRC (x),
3019 gen_binary (IOR, mode, dest, GEN_INT (src << pos)));
3020 else
3021 SUBST (SET_SRC (x),
3022 gen_binary (IOR, mode,
3023 gen_binary (AND, mode, dest,
3024 gen_int_mode (~(mask << pos),
3025 mode)),
3026 GEN_INT (src << pos)));
3027
3028 SUBST (SET_DEST (x), dest);
3029
3030 split = find_split_point (&SET_SRC (x), insn);
3031 if (split && split != &SET_SRC (x))
3032 return split;
3033 }
3034
3035 /* Otherwise, see if this is an operation that we can split into two.
3036 If so, try to split that. */
3037 code = GET_CODE (SET_SRC (x));
3038
3039 switch (code)
3040 {
3041 case AND:
3042 /* If we are AND'ing with a large constant that is only a single
3043 bit and the result is only being used in a context where we
3044 need to know if it is zero or nonzero, replace it with a bit
3045 extraction. This will avoid the large constant, which might
3046 have taken more than one insn to make. If the constant were
3047 not a valid argument to the AND but took only one insn to make,
3048 this is no worse, but if it took more than one insn, it will
3049 be better. */
3050
3051 if (GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3052 && GET_CODE (XEXP (SET_SRC (x), 0)) == REG
3053 && (pos = exact_log2 (INTVAL (XEXP (SET_SRC (x), 1)))) >= 7
3054 && GET_CODE (SET_DEST (x)) == REG
3055 && (split = find_single_use (SET_DEST (x), insn, (rtx*) 0)) != 0
3056 && (GET_CODE (*split) == EQ || GET_CODE (*split) == NE)
3057 && XEXP (*split, 0) == SET_DEST (x)
3058 && XEXP (*split, 1) == const0_rtx)
3059 {
3060 rtx extraction = make_extraction (GET_MODE (SET_DEST (x)),
3061 XEXP (SET_SRC (x), 0),
3062 pos, NULL_RTX, 1, 1, 0, 0);
3063 if (extraction != 0)
3064 {
3065 SUBST (SET_SRC (x), extraction);
3066 return find_split_point (loc, insn);
3067 }
3068 }
3069 break;
3070
3071 case NE:
3072 /* If STORE_FLAG_VALUE is -1, this is (NE X 0) and only one bit of X
3073 is known to be on, this can be converted into a NEG of a shift. */
3074 if (STORE_FLAG_VALUE == -1 && XEXP (SET_SRC (x), 1) == const0_rtx
3075 && GET_MODE (SET_SRC (x)) == GET_MODE (XEXP (SET_SRC (x), 0))
3076 && 1 <= (pos = exact_log2
3077 (nonzero_bits (XEXP (SET_SRC (x), 0),
3078 GET_MODE (XEXP (SET_SRC (x), 0))))))
3079 {
3080 enum machine_mode mode = GET_MODE (XEXP (SET_SRC (x), 0));
3081
3082 SUBST (SET_SRC (x),
3083 gen_rtx_NEG (mode,
3084 gen_rtx_LSHIFTRT (mode,
3085 XEXP (SET_SRC (x), 0),
3086 GEN_INT (pos))));
3087
3088 split = find_split_point (&SET_SRC (x), insn);
3089 if (split && split != &SET_SRC (x))
3090 return split;
3091 }
3092 break;
3093
3094 case SIGN_EXTEND:
3095 inner = XEXP (SET_SRC (x), 0);
3096
3097 /* We can't optimize if either mode is a partial integer
3098 mode as we don't know how many bits are significant
3099 in those modes. */
3100 if (GET_MODE_CLASS (GET_MODE (inner)) == MODE_PARTIAL_INT
3101 || GET_MODE_CLASS (GET_MODE (SET_SRC (x))) == MODE_PARTIAL_INT)
3102 break;
3103
3104 pos = 0;
3105 len = GET_MODE_BITSIZE (GET_MODE (inner));
3106 unsignedp = 0;
3107 break;
3108
3109 case SIGN_EXTRACT:
3110 case ZERO_EXTRACT:
3111 if (GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3112 && GET_CODE (XEXP (SET_SRC (x), 2)) == CONST_INT)
3113 {
3114 inner = XEXP (SET_SRC (x), 0);
3115 len = INTVAL (XEXP (SET_SRC (x), 1));
3116 pos = INTVAL (XEXP (SET_SRC (x), 2));
3117
3118 if (BITS_BIG_ENDIAN)
3119 pos = GET_MODE_BITSIZE (GET_MODE (inner)) - len - pos;
3120 unsignedp = (code == ZERO_EXTRACT);
3121 }
3122 break;
3123
3124 default:
3125 break;
3126 }
3127
3128 if (len && pos >= 0 && pos + len <= GET_MODE_BITSIZE (GET_MODE (inner)))
3129 {
3130 enum machine_mode mode = GET_MODE (SET_SRC (x));
3131
3132 /* For unsigned, we have a choice of a shift followed by an
3133 AND or two shifts. Use two shifts for field sizes where the
3134 constant might be too large. We assume here that we can
3135 always at least get 8-bit constants in an AND insn, which is
3136 true for every current RISC. */
3137
3138 if (unsignedp && len <= 8)
3139 {
3140 SUBST (SET_SRC (x),
3141 gen_rtx_AND (mode,
3142 gen_rtx_LSHIFTRT
3143 (mode, gen_lowpart_for_combine (mode, inner),
3144 GEN_INT (pos)),
3145 GEN_INT (((HOST_WIDE_INT) 1 << len) - 1)));
3146
3147 split = find_split_point (&SET_SRC (x), insn);
3148 if (split && split != &SET_SRC (x))
3149 return split;
3150 }
3151 else
3152 {
3153 SUBST (SET_SRC (x),
3154 gen_rtx_fmt_ee
3155 (unsignedp ? LSHIFTRT : ASHIFTRT, mode,
3156 gen_rtx_ASHIFT (mode,
3157 gen_lowpart_for_combine (mode, inner),
3158 GEN_INT (GET_MODE_BITSIZE (mode)
3159 - len - pos)),
3160 GEN_INT (GET_MODE_BITSIZE (mode) - len)));
3161
3162 split = find_split_point (&SET_SRC (x), insn);
3163 if (split && split != &SET_SRC (x))
3164 return split;
3165 }
3166 }
3167
3168 /* See if this is a simple operation with a constant as the second
3169 operand. It might be that this constant is out of range and hence
3170 could be used as a split point. */
3171 if ((GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '2'
3172 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == 'c'
3173 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '<')
3174 && CONSTANT_P (XEXP (SET_SRC (x), 1))
3175 && (GET_RTX_CLASS (GET_CODE (XEXP (SET_SRC (x), 0))) == 'o'
3176 || (GET_CODE (XEXP (SET_SRC (x), 0)) == SUBREG
3177 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (SET_SRC (x), 0))))
3178 == 'o'))))
3179 return &XEXP (SET_SRC (x), 1);
3180
3181 /* Finally, see if this is a simple operation with its first operand
3182 not in a register. The operation might require this operand in a
3183 register, so return it as a split point. We can always do this
3184 because if the first operand were another operation, we would have
3185 already found it as a split point. */
3186 if ((GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '2'
3187 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == 'c'
3188 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '<'
3189 || GET_RTX_CLASS (GET_CODE (SET_SRC (x))) == '1')
3190 && ! register_operand (XEXP (SET_SRC (x), 0), VOIDmode))
3191 return &XEXP (SET_SRC (x), 0);
3192
3193 return 0;
3194
3195 case AND:
3196 case IOR:
3197 /* We write NOR as (and (not A) (not B)), but if we don't have a NOR,
3198 it is better to write this as (not (ior A B)) so we can split it.
3199 Similarly for IOR. */
3200 if (GET_CODE (XEXP (x, 0)) == NOT && GET_CODE (XEXP (x, 1)) == NOT)
3201 {
3202 SUBST (*loc,
3203 gen_rtx_NOT (GET_MODE (x),
3204 gen_rtx_fmt_ee (code == IOR ? AND : IOR,
3205 GET_MODE (x),
3206 XEXP (XEXP (x, 0), 0),
3207 XEXP (XEXP (x, 1), 0))));
3208 return find_split_point (loc, insn);
3209 }
3210
3211 /* Many RISC machines have a large set of logical insns. If the
3212 second operand is a NOT, put it first so we will try to split the
3213 other operand first. */
3214 if (GET_CODE (XEXP (x, 1)) == NOT)
3215 {
3216 rtx tem = XEXP (x, 0);
3217 SUBST (XEXP (x, 0), XEXP (x, 1));
3218 SUBST (XEXP (x, 1), tem);
3219 }
3220 break;
3221
3222 default:
3223 break;
3224 }
3225
3226 /* Otherwise, select our actions depending on our rtx class. */
3227 switch (GET_RTX_CLASS (code))
3228 {
3229 case 'b': /* This is ZERO_EXTRACT and SIGN_EXTRACT. */
3230 case '3':
3231 split = find_split_point (&XEXP (x, 2), insn);
3232 if (split)
3233 return split;
3234 /* ... fall through ... */
3235 case '2':
3236 case 'c':
3237 case '<':
3238 split = find_split_point (&XEXP (x, 1), insn);
3239 if (split)
3240 return split;
3241 /* ... fall through ... */
3242 case '1':
3243 /* Some machines have (and (shift ...) ...) insns. If X is not
3244 an AND, but XEXP (X, 0) is, use it as our split point. */
3245 if (GET_CODE (x) != AND && GET_CODE (XEXP (x, 0)) == AND)
3246 return &XEXP (x, 0);
3247
3248 split = find_split_point (&XEXP (x, 0), insn);
3249 if (split)
3250 return split;
3251 return loc;
3252 }
3253
3254 /* Otherwise, we don't have a split point. */
3255 return 0;
3256 }
3257
3258 /* Throughout X, replace FROM with TO, and return the result.
3259 The result is TO if X is FROM;
3260 otherwise the result is X, but its contents may have been modified.
3261 If they were modified, a record was made in undobuf so that
3262 undo_all will (among other things) return X to its original state.
3263
3264 If the number of changes necessary is too much to record to undo,
3265 the excess changes are not made, so the result is invalid.
3266 The changes already made can still be undone.
3267 undobuf.num_undo is incremented for such changes, so by testing that
3268 the caller can tell whether the result is valid.
3269
3270 `n_occurrences' is incremented each time FROM is replaced.
3271
3272 IN_DEST is nonzero if we are processing the SET_DEST of a SET.
3273
3274 UNIQUE_COPY is nonzero if each substitution must be unique. We do this
3275 by copying if `n_occurrences' is nonzero. */
3276
3277 static rtx
subst(rtx x,rtx from,rtx to,int in_dest,int unique_copy)3278 subst (rtx x, rtx from, rtx to, int in_dest, int unique_copy)
3279 {
3280 enum rtx_code code = GET_CODE (x);
3281 enum machine_mode op0_mode = VOIDmode;
3282 const char *fmt;
3283 int len, i;
3284 rtx new;
3285
3286 /* Two expressions are equal if they are identical copies of a shared
3287 RTX or if they are both registers with the same register number
3288 and mode. */
3289
3290 #define COMBINE_RTX_EQUAL_P(X,Y) \
3291 ((X) == (Y) \
3292 || (GET_CODE (X) == REG && GET_CODE (Y) == REG \
3293 && REGNO (X) == REGNO (Y) && GET_MODE (X) == GET_MODE (Y)))
3294
3295 if (! in_dest && COMBINE_RTX_EQUAL_P (x, from))
3296 {
3297 n_occurrences++;
3298 return (unique_copy && n_occurrences > 1 ? copy_rtx (to) : to);
3299 }
3300
3301 /* If X and FROM are the same register but different modes, they will
3302 not have been seen as equal above. However, flow.c will make a
3303 LOG_LINKS entry for that case. If we do nothing, we will try to
3304 rerecognize our original insn and, when it succeeds, we will
3305 delete the feeding insn, which is incorrect.
3306
3307 So force this insn not to match in this (rare) case. */
3308 if (! in_dest && code == REG && GET_CODE (from) == REG
3309 && REGNO (x) == REGNO (from))
3310 return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx);
3311
3312 /* If this is an object, we are done unless it is a MEM or LO_SUM, both
3313 of which may contain things that can be combined. */
3314 if (code != MEM && code != LO_SUM && GET_RTX_CLASS (code) == 'o')
3315 return x;
3316
3317 /* It is possible to have a subexpression appear twice in the insn.
3318 Suppose that FROM is a register that appears within TO.
3319 Then, after that subexpression has been scanned once by `subst',
3320 the second time it is scanned, TO may be found. If we were
3321 to scan TO here, we would find FROM within it and create a
3322 self-referent rtl structure which is completely wrong. */
3323 if (COMBINE_RTX_EQUAL_P (x, to))
3324 return to;
3325
3326 /* Parallel asm_operands need special attention because all of the
3327 inputs are shared across the arms. Furthermore, unsharing the
3328 rtl results in recognition failures. Failure to handle this case
3329 specially can result in circular rtl.
3330
3331 Solve this by doing a normal pass across the first entry of the
3332 parallel, and only processing the SET_DESTs of the subsequent
3333 entries. Ug. */
3334
3335 if (code == PARALLEL
3336 && GET_CODE (XVECEXP (x, 0, 0)) == SET
3337 && GET_CODE (SET_SRC (XVECEXP (x, 0, 0))) == ASM_OPERANDS)
3338 {
3339 new = subst (XVECEXP (x, 0, 0), from, to, 0, unique_copy);
3340
3341 /* If this substitution failed, this whole thing fails. */
3342 if (GET_CODE (new) == CLOBBER
3343 && XEXP (new, 0) == const0_rtx)
3344 return new;
3345
3346 SUBST (XVECEXP (x, 0, 0), new);
3347
3348 for (i = XVECLEN (x, 0) - 1; i >= 1; i--)
3349 {
3350 rtx dest = SET_DEST (XVECEXP (x, 0, i));
3351
3352 if (GET_CODE (dest) != REG
3353 && GET_CODE (dest) != CC0
3354 && GET_CODE (dest) != PC)
3355 {
3356 new = subst (dest, from, to, 0, unique_copy);
3357
3358 /* If this substitution failed, this whole thing fails. */
3359 if (GET_CODE (new) == CLOBBER
3360 && XEXP (new, 0) == const0_rtx)
3361 return new;
3362
3363 SUBST (SET_DEST (XVECEXP (x, 0, i)), new);
3364 }
3365 }
3366 }
3367 else
3368 {
3369 len = GET_RTX_LENGTH (code);
3370 fmt = GET_RTX_FORMAT (code);
3371
3372 /* We don't need to process a SET_DEST that is a register, CC0,
3373 or PC, so set up to skip this common case. All other cases
3374 where we want to suppress replacing something inside a
3375 SET_SRC are handled via the IN_DEST operand. */
3376 if (code == SET
3377 && (GET_CODE (SET_DEST (x)) == REG
3378 || GET_CODE (SET_DEST (x)) == CC0
3379 || GET_CODE (SET_DEST (x)) == PC))
3380 fmt = "ie";
3381
3382 /* Get the mode of operand 0 in case X is now a SIGN_EXTEND of a
3383 constant. */
3384 if (fmt[0] == 'e')
3385 op0_mode = GET_MODE (XEXP (x, 0));
3386
3387 for (i = 0; i < len; i++)
3388 {
3389 if (fmt[i] == 'E')
3390 {
3391 int j;
3392 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3393 {
3394 if (COMBINE_RTX_EQUAL_P (XVECEXP (x, i, j), from))
3395 {
3396 new = (unique_copy && n_occurrences
3397 ? copy_rtx (to) : to);
3398 n_occurrences++;
3399 }
3400 else
3401 {
3402 new = subst (XVECEXP (x, i, j), from, to, 0,
3403 unique_copy);
3404
3405 /* If this substitution failed, this whole thing
3406 fails. */
3407 if (GET_CODE (new) == CLOBBER
3408 && XEXP (new, 0) == const0_rtx)
3409 return new;
3410 }
3411
3412 SUBST (XVECEXP (x, i, j), new);
3413 }
3414 }
3415 else if (fmt[i] == 'e')
3416 {
3417 /* If this is a register being set, ignore it. */
3418 new = XEXP (x, i);
3419 if (in_dest
3420 && (code == SUBREG || code == STRICT_LOW_PART
3421 || code == ZERO_EXTRACT)
3422 && i == 0
3423 && GET_CODE (new) == REG)
3424 ;
3425
3426 else if (COMBINE_RTX_EQUAL_P (XEXP (x, i), from))
3427 {
3428 /* In general, don't install a subreg involving two
3429 modes not tieable. It can worsen register
3430 allocation, and can even make invalid reload
3431 insns, since the reg inside may need to be copied
3432 from in the outside mode, and that may be invalid
3433 if it is an fp reg copied in integer mode.
3434
3435 We allow two exceptions to this: It is valid if
3436 it is inside another SUBREG and the mode of that
3437 SUBREG and the mode of the inside of TO is
3438 tieable and it is valid if X is a SET that copies
3439 FROM to CC0. */
3440
3441 if (GET_CODE (to) == SUBREG
3442 && ! MODES_TIEABLE_P (GET_MODE (to),
3443 GET_MODE (SUBREG_REG (to)))
3444 && ! (code == SUBREG
3445 && MODES_TIEABLE_P (GET_MODE (x),
3446 GET_MODE (SUBREG_REG (to))))
3447 #ifdef HAVE_cc0
3448 && ! (code == SET && i == 1 && XEXP (x, 0) == cc0_rtx)
3449 #endif
3450 )
3451 return gen_rtx_CLOBBER (VOIDmode, const0_rtx);
3452
3453 #ifdef CANNOT_CHANGE_MODE_CLASS
3454 if (code == SUBREG
3455 && GET_CODE (to) == REG
3456 && REGNO (to) < FIRST_PSEUDO_REGISTER
3457 && REG_CANNOT_CHANGE_MODE_P (REGNO (to),
3458 GET_MODE (to),
3459 GET_MODE (x)))
3460 return gen_rtx_CLOBBER (VOIDmode, const0_rtx);
3461 #endif
3462
3463 new = (unique_copy && n_occurrences ? copy_rtx (to) : to);
3464 n_occurrences++;
3465 }
3466 else
3467 /* If we are in a SET_DEST, suppress most cases unless we
3468 have gone inside a MEM, in which case we want to
3469 simplify the address. We assume here that things that
3470 are actually part of the destination have their inner
3471 parts in the first expression. This is true for SUBREG,
3472 STRICT_LOW_PART, and ZERO_EXTRACT, which are the only
3473 things aside from REG and MEM that should appear in a
3474 SET_DEST. */
3475 new = subst (XEXP (x, i), from, to,
3476 (((in_dest
3477 && (code == SUBREG || code == STRICT_LOW_PART
3478 || code == ZERO_EXTRACT))
3479 || code == SET)
3480 && i == 0), unique_copy);
3481
3482 /* If we found that we will have to reject this combination,
3483 indicate that by returning the CLOBBER ourselves, rather than
3484 an expression containing it. This will speed things up as
3485 well as prevent accidents where two CLOBBERs are considered
3486 to be equal, thus producing an incorrect simplification. */
3487
3488 if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx)
3489 return new;
3490
3491 if (GET_CODE (x) == SUBREG
3492 && (GET_CODE (new) == CONST_INT
3493 || GET_CODE (new) == CONST_DOUBLE))
3494 {
3495 enum machine_mode mode = GET_MODE (x);
3496
3497 x = simplify_subreg (GET_MODE (x), new,
3498 GET_MODE (SUBREG_REG (x)),
3499 SUBREG_BYTE (x));
3500 if (! x)
3501 x = gen_rtx_CLOBBER (mode, const0_rtx);
3502 }
3503 else if (GET_CODE (new) == CONST_INT
3504 && GET_CODE (x) == ZERO_EXTEND)
3505 {
3506 x = simplify_unary_operation (ZERO_EXTEND, GET_MODE (x),
3507 new, GET_MODE (XEXP (x, 0)));
3508 if (! x)
3509 abort ();
3510 }
3511 else
3512 SUBST (XEXP (x, i), new);
3513 }
3514 }
3515 }
3516
3517 /* Try to simplify X. If the simplification changed the code, it is likely
3518 that further simplification will help, so loop, but limit the number
3519 of repetitions that will be performed. */
3520
3521 for (i = 0; i < 4; i++)
3522 {
3523 /* If X is sufficiently simple, don't bother trying to do anything
3524 with it. */
3525 if (code != CONST_INT && code != REG && code != CLOBBER)
3526 x = combine_simplify_rtx (x, op0_mode, i == 3, in_dest);
3527
3528 if (GET_CODE (x) == code)
3529 break;
3530
3531 code = GET_CODE (x);
3532
3533 /* We no longer know the original mode of operand 0 since we
3534 have changed the form of X) */
3535 op0_mode = VOIDmode;
3536 }
3537
3538 return x;
3539 }
3540
3541 /* Simplify X, a piece of RTL. We just operate on the expression at the
3542 outer level; call `subst' to simplify recursively. Return the new
3543 expression.
3544
3545 OP0_MODE is the original mode of XEXP (x, 0); LAST is nonzero if this
3546 will be the iteration even if an expression with a code different from
3547 X is returned; IN_DEST is nonzero if we are inside a SET_DEST. */
3548
3549 static rtx
combine_simplify_rtx(rtx x,enum machine_mode op0_mode,int last,int in_dest)3550 combine_simplify_rtx (rtx x, enum machine_mode op0_mode, int last,
3551 int in_dest)
3552 {
3553 enum rtx_code code = GET_CODE (x);
3554 enum machine_mode mode = GET_MODE (x);
3555 rtx temp;
3556 rtx reversed;
3557 int i;
3558
3559 /* If this is a commutative operation, put a constant last and a complex
3560 expression first. We don't need to do this for comparisons here. */
3561 if (GET_RTX_CLASS (code) == 'c'
3562 && swap_commutative_operands_p (XEXP (x, 0), XEXP (x, 1)))
3563 {
3564 temp = XEXP (x, 0);
3565 SUBST (XEXP (x, 0), XEXP (x, 1));
3566 SUBST (XEXP (x, 1), temp);
3567 }
3568
3569 /* If this is a PLUS, MINUS, or MULT, and the first operand is the
3570 sign extension of a PLUS with a constant, reverse the order of the sign
3571 extension and the addition. Note that this not the same as the original
3572 code, but overflow is undefined for signed values. Also note that the
3573 PLUS will have been partially moved "inside" the sign-extension, so that
3574 the first operand of X will really look like:
3575 (ashiftrt (plus (ashift A C4) C5) C4).
3576 We convert this to
3577 (plus (ashiftrt (ashift A C4) C2) C4)
3578 and replace the first operand of X with that expression. Later parts
3579 of this function may simplify the expression further.
3580
3581 For example, if we start with (mult (sign_extend (plus A C1)) C2),
3582 we swap the SIGN_EXTEND and PLUS. Later code will apply the
3583 distributive law to produce (plus (mult (sign_extend X) C1) C3).
3584
3585 We do this to simplify address expressions. */
3586
3587 if ((code == PLUS || code == MINUS || code == MULT)
3588 && GET_CODE (XEXP (x, 0)) == ASHIFTRT
3589 && GET_CODE (XEXP (XEXP (x, 0), 0)) == PLUS
3590 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == ASHIFT
3591 && GET_CODE (XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 1)) == CONST_INT
3592 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
3593 && XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 1) == XEXP (XEXP (x, 0), 1)
3594 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT
3595 && (temp = simplify_binary_operation (ASHIFTRT, mode,
3596 XEXP (XEXP (XEXP (x, 0), 0), 1),
3597 XEXP (XEXP (x, 0), 1))) != 0)
3598 {
3599 rtx new
3600 = simplify_shift_const (NULL_RTX, ASHIFT, mode,
3601 XEXP (XEXP (XEXP (XEXP (x, 0), 0), 0), 0),
3602 INTVAL (XEXP (XEXP (x, 0), 1)));
3603
3604 new = simplify_shift_const (NULL_RTX, ASHIFTRT, mode, new,
3605 INTVAL (XEXP (XEXP (x, 0), 1)));
3606
3607 SUBST (XEXP (x, 0), gen_binary (PLUS, mode, new, temp));
3608 }
3609
3610 /* If this is a simple operation applied to an IF_THEN_ELSE, try
3611 applying it to the arms of the IF_THEN_ELSE. This often simplifies
3612 things. Check for cases where both arms are testing the same
3613 condition.
3614
3615 Don't do anything if all operands are very simple. */
3616
3617 if (((GET_RTX_CLASS (code) == '2' || GET_RTX_CLASS (code) == 'c'
3618 || GET_RTX_CLASS (code) == '<')
3619 && ((GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) != 'o'
3620 && ! (GET_CODE (XEXP (x, 0)) == SUBREG
3621 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0))))
3622 == 'o')))
3623 || (GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) != 'o'
3624 && ! (GET_CODE (XEXP (x, 1)) == SUBREG
3625 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 1))))
3626 == 'o')))))
3627 || (GET_RTX_CLASS (code) == '1'
3628 && ((GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) != 'o'
3629 && ! (GET_CODE (XEXP (x, 0)) == SUBREG
3630 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0))))
3631 == 'o'))))))
3632 {
3633 rtx cond, true_rtx, false_rtx;
3634
3635 cond = if_then_else_cond (x, &true_rtx, &false_rtx);
3636 if (cond != 0
3637 /* If everything is a comparison, what we have is highly unlikely
3638 to be simpler, so don't use it. */
3639 && ! (GET_RTX_CLASS (code) == '<'
3640 && (GET_RTX_CLASS (GET_CODE (true_rtx)) == '<'
3641 || GET_RTX_CLASS (GET_CODE (false_rtx)) == '<')))
3642 {
3643 rtx cop1 = const0_rtx;
3644 enum rtx_code cond_code = simplify_comparison (NE, &cond, &cop1);
3645
3646 if (cond_code == NE && GET_RTX_CLASS (GET_CODE (cond)) == '<')
3647 return x;
3648
3649 /* Simplify the alternative arms; this may collapse the true and
3650 false arms to store-flag values. Be careful to use copy_rtx
3651 here since true_rtx or false_rtx might share RTL with x as a
3652 result of the if_then_else_cond call above. */
3653 true_rtx = subst (copy_rtx (true_rtx), pc_rtx, pc_rtx, 0, 0);
3654 false_rtx = subst (copy_rtx (false_rtx), pc_rtx, pc_rtx, 0, 0);
3655
3656 /* If true_rtx and false_rtx are not general_operands, an if_then_else
3657 is unlikely to be simpler. */
3658 if (general_operand (true_rtx, VOIDmode)
3659 && general_operand (false_rtx, VOIDmode))
3660 {
3661 enum rtx_code reversed;
3662
3663 /* Restarting if we generate a store-flag expression will cause
3664 us to loop. Just drop through in this case. */
3665
3666 /* If the result values are STORE_FLAG_VALUE and zero, we can
3667 just make the comparison operation. */
3668 if (true_rtx == const_true_rtx && false_rtx == const0_rtx)
3669 x = gen_binary (cond_code, mode, cond, cop1);
3670 else if (true_rtx == const0_rtx && false_rtx == const_true_rtx
3671 && ((reversed = reversed_comparison_code_parts
3672 (cond_code, cond, cop1, NULL))
3673 != UNKNOWN))
3674 x = gen_binary (reversed, mode, cond, cop1);
3675
3676 /* Likewise, we can make the negate of a comparison operation
3677 if the result values are - STORE_FLAG_VALUE and zero. */
3678 else if (GET_CODE (true_rtx) == CONST_INT
3679 && INTVAL (true_rtx) == - STORE_FLAG_VALUE
3680 && false_rtx == const0_rtx)
3681 x = simplify_gen_unary (NEG, mode,
3682 gen_binary (cond_code, mode, cond,
3683 cop1),
3684 mode);
3685 else if (GET_CODE (false_rtx) == CONST_INT
3686 && INTVAL (false_rtx) == - STORE_FLAG_VALUE
3687 && true_rtx == const0_rtx
3688 && ((reversed = reversed_comparison_code_parts
3689 (cond_code, cond, cop1, NULL))
3690 != UNKNOWN))
3691 x = simplify_gen_unary (NEG, mode,
3692 gen_binary (reversed, mode,
3693 cond, cop1),
3694 mode);
3695 else
3696 return gen_rtx_IF_THEN_ELSE (mode,
3697 gen_binary (cond_code, VOIDmode,
3698 cond, cop1),
3699 true_rtx, false_rtx);
3700
3701 code = GET_CODE (x);
3702 op0_mode = VOIDmode;
3703 }
3704 }
3705 }
3706
3707 /* Try to fold this expression in case we have constants that weren't
3708 present before. */
3709 temp = 0;
3710 switch (GET_RTX_CLASS (code))
3711 {
3712 case '1':
3713 if (op0_mode == VOIDmode)
3714 op0_mode = GET_MODE (XEXP (x, 0));
3715 temp = simplify_unary_operation (code, mode, XEXP (x, 0), op0_mode);
3716 break;
3717 case '<':
3718 {
3719 enum machine_mode cmp_mode = GET_MODE (XEXP (x, 0));
3720 if (cmp_mode == VOIDmode)
3721 {
3722 cmp_mode = GET_MODE (XEXP (x, 1));
3723 if (cmp_mode == VOIDmode)
3724 cmp_mode = op0_mode;
3725 }
3726 temp = simplify_relational_operation (code, cmp_mode,
3727 XEXP (x, 0), XEXP (x, 1));
3728 }
3729 #ifdef FLOAT_STORE_FLAG_VALUE
3730 if (temp != 0 && GET_MODE_CLASS (mode) == MODE_FLOAT)
3731 {
3732 if (temp == const0_rtx)
3733 temp = CONST0_RTX (mode);
3734 else
3735 temp = CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE (mode),
3736 mode);
3737 }
3738 #endif
3739 break;
3740 case 'c':
3741 case '2':
3742 temp = simplify_binary_operation (code, mode, XEXP (x, 0), XEXP (x, 1));
3743 break;
3744 case 'b':
3745 case '3':
3746 temp = simplify_ternary_operation (code, mode, op0_mode, XEXP (x, 0),
3747 XEXP (x, 1), XEXP (x, 2));
3748 break;
3749 }
3750
3751 if (temp)
3752 {
3753 x = temp;
3754 code = GET_CODE (temp);
3755 op0_mode = VOIDmode;
3756 mode = GET_MODE (temp);
3757 }
3758
3759 /* First see if we can apply the inverse distributive law. */
3760 if (code == PLUS || code == MINUS
3761 || code == AND || code == IOR || code == XOR)
3762 {
3763 x = apply_distributive_law (x);
3764 code = GET_CODE (x);
3765 op0_mode = VOIDmode;
3766 }
3767
3768 /* If CODE is an associative operation not otherwise handled, see if we
3769 can associate some operands. This can win if they are constants or
3770 if they are logically related (i.e. (a & b) & a). */
3771 if ((code == PLUS || code == MINUS || code == MULT || code == DIV
3772 || code == AND || code == IOR || code == XOR
3773 || code == SMAX || code == SMIN || code == UMAX || code == UMIN)
3774 && ((INTEGRAL_MODE_P (mode) && code != DIV)
3775 || (flag_unsafe_math_optimizations && FLOAT_MODE_P (mode))))
3776 {
3777 if (GET_CODE (XEXP (x, 0)) == code)
3778 {
3779 rtx other = XEXP (XEXP (x, 0), 0);
3780 rtx inner_op0 = XEXP (XEXP (x, 0), 1);
3781 rtx inner_op1 = XEXP (x, 1);
3782 rtx inner;
3783
3784 /* Make sure we pass the constant operand if any as the second
3785 one if this is a commutative operation. */
3786 if (CONSTANT_P (inner_op0) && GET_RTX_CLASS (code) == 'c')
3787 {
3788 rtx tem = inner_op0;
3789 inner_op0 = inner_op1;
3790 inner_op1 = tem;
3791 }
3792 inner = simplify_binary_operation (code == MINUS ? PLUS
3793 : code == DIV ? MULT
3794 : code,
3795 mode, inner_op0, inner_op1);
3796
3797 /* For commutative operations, try the other pair if that one
3798 didn't simplify. */
3799 if (inner == 0 && GET_RTX_CLASS (code) == 'c')
3800 {
3801 other = XEXP (XEXP (x, 0), 1);
3802 inner = simplify_binary_operation (code, mode,
3803 XEXP (XEXP (x, 0), 0),
3804 XEXP (x, 1));
3805 }
3806
3807 if (inner)
3808 return gen_binary (code, mode, other, inner);
3809 }
3810 }
3811
3812 /* A little bit of algebraic simplification here. */
3813 switch (code)
3814 {
3815 case MEM:
3816 /* Ensure that our address has any ASHIFTs converted to MULT in case
3817 address-recognizing predicates are called later. */
3818 temp = make_compound_operation (XEXP (x, 0), MEM);
3819 SUBST (XEXP (x, 0), temp);
3820 break;
3821
3822 case SUBREG:
3823 if (op0_mode == VOIDmode)
3824 op0_mode = GET_MODE (SUBREG_REG (x));
3825
3826 /* simplify_subreg can't use gen_lowpart_for_combine. */
3827 if (CONSTANT_P (SUBREG_REG (x))
3828 && subreg_lowpart_offset (mode, op0_mode) == SUBREG_BYTE (x)
3829 /* Don't call gen_lowpart_for_combine if the inner mode
3830 is VOIDmode and we cannot simplify it, as SUBREG without
3831 inner mode is invalid. */
3832 && (GET_MODE (SUBREG_REG (x)) != VOIDmode
3833 || gen_lowpart_common (mode, SUBREG_REG (x))))
3834 return gen_lowpart_for_combine (mode, SUBREG_REG (x));
3835
3836 if (GET_MODE_CLASS (GET_MODE (SUBREG_REG (x))) == MODE_CC)
3837 break;
3838 {
3839 rtx temp;
3840 temp = simplify_subreg (mode, SUBREG_REG (x), op0_mode,
3841 SUBREG_BYTE (x));
3842 if (temp)
3843 return temp;
3844 }
3845
3846 /* Don't change the mode of the MEM if that would change the meaning
3847 of the address. */
3848 if (GET_CODE (SUBREG_REG (x)) == MEM
3849 && (MEM_VOLATILE_P (SUBREG_REG (x))
3850 || mode_dependent_address_p (XEXP (SUBREG_REG (x), 0))))
3851 return gen_rtx_CLOBBER (mode, const0_rtx);
3852
3853 /* Note that we cannot do any narrowing for non-constants since
3854 we might have been counting on using the fact that some bits were
3855 zero. We now do this in the SET. */
3856
3857 break;
3858
3859 case NOT:
3860 if (GET_CODE (XEXP (x, 0)) == SUBREG
3861 && subreg_lowpart_p (XEXP (x, 0))
3862 && (GET_MODE_SIZE (GET_MODE (XEXP (x, 0)))
3863 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (x, 0)))))
3864 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == ASHIFT
3865 && XEXP (SUBREG_REG (XEXP (x, 0)), 0) == const1_rtx)
3866 {
3867 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (XEXP (x, 0)));
3868
3869 x = gen_rtx_ROTATE (inner_mode,
3870 simplify_gen_unary (NOT, inner_mode, const1_rtx,
3871 inner_mode),
3872 XEXP (SUBREG_REG (XEXP (x, 0)), 1));
3873 return gen_lowpart_for_combine (mode, x);
3874 }
3875
3876 /* Apply De Morgan's laws to reduce number of patterns for machines
3877 with negating logical insns (and-not, nand, etc.). If result has
3878 only one NOT, put it first, since that is how the patterns are
3879 coded. */
3880
3881 if (GET_CODE (XEXP (x, 0)) == IOR || GET_CODE (XEXP (x, 0)) == AND)
3882 {
3883 rtx in1 = XEXP (XEXP (x, 0), 0), in2 = XEXP (XEXP (x, 0), 1);
3884 enum machine_mode op_mode;
3885
3886 op_mode = GET_MODE (in1);
3887 in1 = simplify_gen_unary (NOT, op_mode, in1, op_mode);
3888
3889 op_mode = GET_MODE (in2);
3890 if (op_mode == VOIDmode)
3891 op_mode = mode;
3892 in2 = simplify_gen_unary (NOT, op_mode, in2, op_mode);
3893
3894 if (GET_CODE (in2) == NOT && GET_CODE (in1) != NOT)
3895 {
3896 rtx tem = in2;
3897 in2 = in1; in1 = tem;
3898 }
3899
3900 return gen_rtx_fmt_ee (GET_CODE (XEXP (x, 0)) == IOR ? AND : IOR,
3901 mode, in1, in2);
3902 }
3903 break;
3904
3905 case NEG:
3906 /* (neg (xor A 1)) is (plus A -1) if A is known to be either 0 or 1. */
3907 if (GET_CODE (XEXP (x, 0)) == XOR
3908 && XEXP (XEXP (x, 0), 1) == const1_rtx
3909 && nonzero_bits (XEXP (XEXP (x, 0), 0), mode) == 1)
3910 return gen_binary (PLUS, mode, XEXP (XEXP (x, 0), 0), constm1_rtx);
3911
3912 temp = expand_compound_operation (XEXP (x, 0));
3913
3914 /* For C equal to the width of MODE minus 1, (neg (ashiftrt X C)) can be
3915 replaced by (lshiftrt X C). This will convert
3916 (neg (sign_extract X 1 Y)) to (zero_extract X 1 Y). */
3917
3918 if (GET_CODE (temp) == ASHIFTRT
3919 && GET_CODE (XEXP (temp, 1)) == CONST_INT
3920 && INTVAL (XEXP (temp, 1)) == GET_MODE_BITSIZE (mode) - 1)
3921 return simplify_shift_const (temp, LSHIFTRT, mode, XEXP (temp, 0),
3922 INTVAL (XEXP (temp, 1)));
3923
3924 /* If X has only a single bit that might be nonzero, say, bit I, convert
3925 (neg X) to (ashiftrt (ashift X C-I) C-I) where C is the bitsize of
3926 MODE minus 1. This will convert (neg (zero_extract X 1 Y)) to
3927 (sign_extract X 1 Y). But only do this if TEMP isn't a register
3928 or a SUBREG of one since we'd be making the expression more
3929 complex if it was just a register. */
3930
3931 if (GET_CODE (temp) != REG
3932 && ! (GET_CODE (temp) == SUBREG
3933 && GET_CODE (SUBREG_REG (temp)) == REG)
3934 && (i = exact_log2 (nonzero_bits (temp, mode))) >= 0)
3935 {
3936 rtx temp1 = simplify_shift_const
3937 (NULL_RTX, ASHIFTRT, mode,
3938 simplify_shift_const (NULL_RTX, ASHIFT, mode, temp,
3939 GET_MODE_BITSIZE (mode) - 1 - i),
3940 GET_MODE_BITSIZE (mode) - 1 - i);
3941
3942 /* If all we did was surround TEMP with the two shifts, we
3943 haven't improved anything, so don't use it. Otherwise,
3944 we are better off with TEMP1. */
3945 if (GET_CODE (temp1) != ASHIFTRT
3946 || GET_CODE (XEXP (temp1, 0)) != ASHIFT
3947 || XEXP (XEXP (temp1, 0), 0) != temp)
3948 return temp1;
3949 }
3950 break;
3951
3952 case TRUNCATE:
3953 /* We can't handle truncation to a partial integer mode here
3954 because we don't know the real bitsize of the partial
3955 integer mode. */
3956 if (GET_MODE_CLASS (mode) == MODE_PARTIAL_INT)
3957 break;
3958
3959 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
3960 && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
3961 GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))))
3962 SUBST (XEXP (x, 0),
3963 force_to_mode (XEXP (x, 0), GET_MODE (XEXP (x, 0)),
3964 GET_MODE_MASK (mode), NULL_RTX, 0));
3965
3966 /* (truncate:SI ({sign,zero}_extend:DI foo:SI)) == foo:SI. */
3967 if ((GET_CODE (XEXP (x, 0)) == SIGN_EXTEND
3968 || GET_CODE (XEXP (x, 0)) == ZERO_EXTEND)
3969 && GET_MODE (XEXP (XEXP (x, 0), 0)) == mode)
3970 return XEXP (XEXP (x, 0), 0);
3971
3972 /* (truncate:SI (OP:DI ({sign,zero}_extend:DI foo:SI))) is
3973 (OP:SI foo:SI) if OP is NEG or ABS. */
3974 if ((GET_CODE (XEXP (x, 0)) == ABS
3975 || GET_CODE (XEXP (x, 0)) == NEG)
3976 && (GET_CODE (XEXP (XEXP (x, 0), 0)) == SIGN_EXTEND
3977 || GET_CODE (XEXP (XEXP (x, 0), 0)) == ZERO_EXTEND)
3978 && GET_MODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == mode)
3979 return simplify_gen_unary (GET_CODE (XEXP (x, 0)), mode,
3980 XEXP (XEXP (XEXP (x, 0), 0), 0), mode);
3981
3982 /* (truncate:SI (subreg:DI (truncate:SI X) 0)) is
3983 (truncate:SI x). */
3984 if (GET_CODE (XEXP (x, 0)) == SUBREG
3985 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == TRUNCATE
3986 && subreg_lowpart_p (XEXP (x, 0)))
3987 return SUBREG_REG (XEXP (x, 0));
3988
3989 /* If we know that the value is already truncated, we can
3990 replace the TRUNCATE with a SUBREG if TRULY_NOOP_TRUNCATION
3991 is nonzero for the corresponding modes. But don't do this
3992 for an (LSHIFTRT (MULT ...)) since this will cause problems
3993 with the umulXi3_highpart patterns. */
3994 if (TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
3995 GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))))
3996 && num_sign_bit_copies (XEXP (x, 0), GET_MODE (XEXP (x, 0)))
3997 >= (unsigned int) (GET_MODE_BITSIZE (mode) + 1)
3998 && ! (GET_CODE (XEXP (x, 0)) == LSHIFTRT
3999 && GET_CODE (XEXP (XEXP (x, 0), 0)) == MULT))
4000 return gen_lowpart_for_combine (mode, XEXP (x, 0));
4001
4002 /* A truncate of a comparison can be replaced with a subreg if
4003 STORE_FLAG_VALUE permits. This is like the previous test,
4004 but it works even if the comparison is done in a mode larger
4005 than HOST_BITS_PER_WIDE_INT. */
4006 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4007 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
4008 && ((HOST_WIDE_INT) STORE_FLAG_VALUE & ~GET_MODE_MASK (mode)) == 0)
4009 return gen_lowpart_for_combine (mode, XEXP (x, 0));
4010
4011 /* Similarly, a truncate of a register whose value is a
4012 comparison can be replaced with a subreg if STORE_FLAG_VALUE
4013 permits. */
4014 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4015 && ((HOST_WIDE_INT) STORE_FLAG_VALUE & ~GET_MODE_MASK (mode)) == 0
4016 && (temp = get_last_value (XEXP (x, 0)))
4017 && GET_RTX_CLASS (GET_CODE (temp)) == '<')
4018 return gen_lowpart_for_combine (mode, XEXP (x, 0));
4019
4020 break;
4021
4022 case FLOAT_TRUNCATE:
4023 /* (float_truncate:SF (float_extend:DF foo:SF)) = foo:SF. */
4024 if (GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND
4025 && GET_MODE (XEXP (XEXP (x, 0), 0)) == mode)
4026 return XEXP (XEXP (x, 0), 0);
4027
4028 /* (float_truncate:SF (float_truncate:DF foo:XF))
4029 = (float_truncate:SF foo:XF).
4030 This may eliminate double rounding, so it is unsafe.
4031
4032 (float_truncate:SF (float_extend:XF foo:DF))
4033 = (float_truncate:SF foo:DF).
4034
4035 (float_truncate:DF (float_extend:XF foo:SF))
4036 = (float_extend:SF foo:DF). */
4037 if ((GET_CODE (XEXP (x, 0)) == FLOAT_TRUNCATE
4038 && flag_unsafe_math_optimizations)
4039 || GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND)
4040 return simplify_gen_unary (GET_MODE_SIZE (GET_MODE (XEXP (XEXP (x, 0),
4041 0)))
4042 > GET_MODE_SIZE (mode)
4043 ? FLOAT_TRUNCATE : FLOAT_EXTEND,
4044 mode,
4045 XEXP (XEXP (x, 0), 0), mode);
4046
4047 /* (float_truncate (float x)) is (float x) */
4048 if (GET_CODE (XEXP (x, 0)) == FLOAT
4049 && (flag_unsafe_math_optimizations
4050 || ((unsigned)significand_size (GET_MODE (XEXP (x, 0)))
4051 >= (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (x, 0), 0)))
4052 - num_sign_bit_copies (XEXP (XEXP (x, 0), 0),
4053 GET_MODE (XEXP (XEXP (x, 0), 0)))))))
4054 return simplify_gen_unary (FLOAT, mode,
4055 XEXP (XEXP (x, 0), 0),
4056 GET_MODE (XEXP (XEXP (x, 0), 0)));
4057
4058 /* (float_truncate:SF (OP:DF (float_extend:DF foo:sf))) is
4059 (OP:SF foo:SF) if OP is NEG or ABS. */
4060 if ((GET_CODE (XEXP (x, 0)) == ABS
4061 || GET_CODE (XEXP (x, 0)) == NEG)
4062 && GET_CODE (XEXP (XEXP (x, 0), 0)) == FLOAT_EXTEND
4063 && GET_MODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == mode)
4064 return simplify_gen_unary (GET_CODE (XEXP (x, 0)), mode,
4065 XEXP (XEXP (XEXP (x, 0), 0), 0), mode);
4066
4067 /* (float_truncate:SF (subreg:DF (float_truncate:SF X) 0))
4068 is (float_truncate:SF x). */
4069 if (GET_CODE (XEXP (x, 0)) == SUBREG
4070 && subreg_lowpart_p (XEXP (x, 0))
4071 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == FLOAT_TRUNCATE)
4072 return SUBREG_REG (XEXP (x, 0));
4073 break;
4074 case FLOAT_EXTEND:
4075 /* (float_extend (float_extend x)) is (float_extend x)
4076
4077 (float_extend (float x)) is (float x) assuming that double
4078 rounding can't happen.
4079 */
4080 if (GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND
4081 || (GET_CODE (XEXP (x, 0)) == FLOAT
4082 && ((unsigned)significand_size (GET_MODE (XEXP (x, 0)))
4083 >= (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (x, 0), 0)))
4084 - num_sign_bit_copies (XEXP (XEXP (x, 0), 0),
4085 GET_MODE (XEXP (XEXP (x, 0), 0)))))))
4086 return simplify_gen_unary (GET_CODE (XEXP (x, 0)), mode,
4087 XEXP (XEXP (x, 0), 0),
4088 GET_MODE (XEXP (XEXP (x, 0), 0)));
4089
4090 break;
4091 #ifdef HAVE_cc0
4092 case COMPARE:
4093 /* Convert (compare FOO (const_int 0)) to FOO unless we aren't
4094 using cc0, in which case we want to leave it as a COMPARE
4095 so we can distinguish it from a register-register-copy. */
4096 if (XEXP (x, 1) == const0_rtx)
4097 return XEXP (x, 0);
4098
4099 /* x - 0 is the same as x unless x's mode has signed zeros and
4100 allows rounding towards -infinity. Under those conditions,
4101 0 - 0 is -0. */
4102 if (!(HONOR_SIGNED_ZEROS (GET_MODE (XEXP (x, 0)))
4103 && HONOR_SIGN_DEPENDENT_ROUNDING (GET_MODE (XEXP (x, 0))))
4104 && XEXP (x, 1) == CONST0_RTX (GET_MODE (XEXP (x, 0))))
4105 return XEXP (x, 0);
4106 break;
4107 #endif
4108
4109 case CONST:
4110 /* (const (const X)) can become (const X). Do it this way rather than
4111 returning the inner CONST since CONST can be shared with a
4112 REG_EQUAL note. */
4113 if (GET_CODE (XEXP (x, 0)) == CONST)
4114 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4115 break;
4116
4117 #ifdef HAVE_lo_sum
4118 case LO_SUM:
4119 /* Convert (lo_sum (high FOO) FOO) to FOO. This is necessary so we
4120 can add in an offset. find_split_point will split this address up
4121 again if it doesn't match. */
4122 if (GET_CODE (XEXP (x, 0)) == HIGH
4123 && rtx_equal_p (XEXP (XEXP (x, 0), 0), XEXP (x, 1)))
4124 return XEXP (x, 1);
4125 break;
4126 #endif
4127
4128 case PLUS:
4129 /* Canonicalize (plus (mult (neg B) C) A) to (minus A (mult B C)).
4130 */
4131 if (GET_CODE (XEXP (x, 0)) == MULT
4132 && GET_CODE (XEXP (XEXP (x, 0), 0)) == NEG)
4133 {
4134 rtx in1, in2;
4135
4136 in1 = XEXP (XEXP (XEXP (x, 0), 0), 0);
4137 in2 = XEXP (XEXP (x, 0), 1);
4138 return gen_binary (MINUS, mode, XEXP (x, 1),
4139 gen_binary (MULT, mode, in1, in2));
4140 }
4141
4142 /* If we have (plus (plus (A const) B)), associate it so that CONST is
4143 outermost. That's because that's the way indexed addresses are
4144 supposed to appear. This code used to check many more cases, but
4145 they are now checked elsewhere. */
4146 if (GET_CODE (XEXP (x, 0)) == PLUS
4147 && CONSTANT_ADDRESS_P (XEXP (XEXP (x, 0), 1)))
4148 return gen_binary (PLUS, mode,
4149 gen_binary (PLUS, mode, XEXP (XEXP (x, 0), 0),
4150 XEXP (x, 1)),
4151 XEXP (XEXP (x, 0), 1));
4152
4153 /* (plus (xor (and <foo> (const_int pow2 - 1)) <c>) <-c>)
4154 when c is (const_int (pow2 + 1) / 2) is a sign extension of a
4155 bit-field and can be replaced by either a sign_extend or a
4156 sign_extract. The `and' may be a zero_extend and the two
4157 <c>, -<c> constants may be reversed. */
4158 if (GET_CODE (XEXP (x, 0)) == XOR
4159 && GET_CODE (XEXP (x, 1)) == CONST_INT
4160 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4161 && INTVAL (XEXP (x, 1)) == -INTVAL (XEXP (XEXP (x, 0), 1))
4162 && ((i = exact_log2 (INTVAL (XEXP (XEXP (x, 0), 1)))) >= 0
4163 || (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0)
4164 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4165 && ((GET_CODE (XEXP (XEXP (x, 0), 0)) == AND
4166 && GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == CONST_INT
4167 && (INTVAL (XEXP (XEXP (XEXP (x, 0), 0), 1))
4168 == ((HOST_WIDE_INT) 1 << (i + 1)) - 1))
4169 || (GET_CODE (XEXP (XEXP (x, 0), 0)) == ZERO_EXTEND
4170 && (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (XEXP (x, 0), 0), 0)))
4171 == (unsigned int) i + 1))))
4172 return simplify_shift_const
4173 (NULL_RTX, ASHIFTRT, mode,
4174 simplify_shift_const (NULL_RTX, ASHIFT, mode,
4175 XEXP (XEXP (XEXP (x, 0), 0), 0),
4176 GET_MODE_BITSIZE (mode) - (i + 1)),
4177 GET_MODE_BITSIZE (mode) - (i + 1));
4178
4179 /* (plus (comparison A B) C) can become (neg (rev-comp A B)) if
4180 C is 1 and STORE_FLAG_VALUE is -1 or if C is -1 and STORE_FLAG_VALUE
4181 is 1. This produces better code than the alternative immediately
4182 below. */
4183 if (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == '<'
4184 && ((STORE_FLAG_VALUE == -1 && XEXP (x, 1) == const1_rtx)
4185 || (STORE_FLAG_VALUE == 1 && XEXP (x, 1) == constm1_rtx))
4186 && (reversed = reversed_comparison (XEXP (x, 0), mode,
4187 XEXP (XEXP (x, 0), 0),
4188 XEXP (XEXP (x, 0), 1))))
4189 return
4190 simplify_gen_unary (NEG, mode, reversed, mode);
4191
4192 /* If only the low-order bit of X is possibly nonzero, (plus x -1)
4193 can become (ashiftrt (ashift (xor x 1) C) C) where C is
4194 the bitsize of the mode - 1. This allows simplification of
4195 "a = (b & 8) == 0;" */
4196 if (XEXP (x, 1) == constm1_rtx
4197 && GET_CODE (XEXP (x, 0)) != REG
4198 && ! (GET_CODE (XEXP (x, 0)) == SUBREG
4199 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == REG)
4200 && nonzero_bits (XEXP (x, 0), mode) == 1)
4201 return simplify_shift_const (NULL_RTX, ASHIFTRT, mode,
4202 simplify_shift_const (NULL_RTX, ASHIFT, mode,
4203 gen_rtx_XOR (mode, XEXP (x, 0), const1_rtx),
4204 GET_MODE_BITSIZE (mode) - 1),
4205 GET_MODE_BITSIZE (mode) - 1);
4206
4207 /* If we are adding two things that have no bits in common, convert
4208 the addition into an IOR. This will often be further simplified,
4209 for example in cases like ((a & 1) + (a & 2)), which can
4210 become a & 3. */
4211
4212 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4213 && (nonzero_bits (XEXP (x, 0), mode)
4214 & nonzero_bits (XEXP (x, 1), mode)) == 0)
4215 {
4216 /* Try to simplify the expression further. */
4217 rtx tor = gen_binary (IOR, mode, XEXP (x, 0), XEXP (x, 1));
4218 temp = combine_simplify_rtx (tor, mode, last, in_dest);
4219
4220 /* If we could, great. If not, do not go ahead with the IOR
4221 replacement, since PLUS appears in many special purpose
4222 address arithmetic instructions. */
4223 if (GET_CODE (temp) != CLOBBER && temp != tor)
4224 return temp;
4225 }
4226 break;
4227
4228 case MINUS:
4229 /* If STORE_FLAG_VALUE is 1, (minus 1 (comparison foo bar)) can be done
4230 by reversing the comparison code if valid. */
4231 if (STORE_FLAG_VALUE == 1
4232 && XEXP (x, 0) == const1_rtx
4233 && GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) == '<'
4234 && (reversed = reversed_comparison (XEXP (x, 1), mode,
4235 XEXP (XEXP (x, 1), 0),
4236 XEXP (XEXP (x, 1), 1))))
4237 return reversed;
4238
4239 /* (minus <foo> (and <foo> (const_int -pow2))) becomes
4240 (and <foo> (const_int pow2-1)) */
4241 if (GET_CODE (XEXP (x, 1)) == AND
4242 && GET_CODE (XEXP (XEXP (x, 1), 1)) == CONST_INT
4243 && exact_log2 (-INTVAL (XEXP (XEXP (x, 1), 1))) >= 0
4244 && rtx_equal_p (XEXP (XEXP (x, 1), 0), XEXP (x, 0)))
4245 return simplify_and_const_int (NULL_RTX, mode, XEXP (x, 0),
4246 -INTVAL (XEXP (XEXP (x, 1), 1)) - 1);
4247
4248 /* Canonicalize (minus A (mult (neg B) C)) to (plus (mult B C) A).
4249 */
4250 if (GET_CODE (XEXP (x, 1)) == MULT
4251 && GET_CODE (XEXP (XEXP (x, 1), 0)) == NEG)
4252 {
4253 rtx in1, in2;
4254
4255 in1 = XEXP (XEXP (XEXP (x, 1), 0), 0);
4256 in2 = XEXP (XEXP (x, 1), 1);
4257 return gen_binary (PLUS, mode, gen_binary (MULT, mode, in1, in2),
4258 XEXP (x, 0));
4259 }
4260
4261 /* Canonicalize (minus (neg A) (mult B C)) to
4262 (minus (mult (neg B) C) A). */
4263 if (GET_CODE (XEXP (x, 1)) == MULT
4264 && GET_CODE (XEXP (x, 0)) == NEG)
4265 {
4266 rtx in1, in2;
4267
4268 in1 = simplify_gen_unary (NEG, mode, XEXP (XEXP (x, 1), 0), mode);
4269 in2 = XEXP (XEXP (x, 1), 1);
4270 return gen_binary (MINUS, mode, gen_binary (MULT, mode, in1, in2),
4271 XEXP (XEXP (x, 0), 0));
4272 }
4273
4274 /* Canonicalize (minus A (plus B C)) to (minus (minus A B) C) for
4275 integers. */
4276 if (GET_CODE (XEXP (x, 1)) == PLUS && INTEGRAL_MODE_P (mode))
4277 return gen_binary (MINUS, mode,
4278 gen_binary (MINUS, mode, XEXP (x, 0),
4279 XEXP (XEXP (x, 1), 0)),
4280 XEXP (XEXP (x, 1), 1));
4281 break;
4282
4283 case MULT:
4284 /* If we have (mult (plus A B) C), apply the distributive law and then
4285 the inverse distributive law to see if things simplify. This
4286 occurs mostly in addresses, often when unrolling loops. */
4287
4288 if (GET_CODE (XEXP (x, 0)) == PLUS)
4289 {
4290 x = apply_distributive_law
4291 (gen_binary (PLUS, mode,
4292 gen_binary (MULT, mode,
4293 XEXP (XEXP (x, 0), 0), XEXP (x, 1)),
4294 gen_binary (MULT, mode,
4295 XEXP (XEXP (x, 0), 1),
4296 copy_rtx (XEXP (x, 1)))));
4297
4298 if (GET_CODE (x) != MULT)
4299 return x;
4300 }
4301 /* Try simplify a*(b/c) as (a*b)/c. */
4302 if (FLOAT_MODE_P (mode) && flag_unsafe_math_optimizations
4303 && GET_CODE (XEXP (x, 0)) == DIV)
4304 {
4305 rtx tem = simplify_binary_operation (MULT, mode,
4306 XEXP (XEXP (x, 0), 0),
4307 XEXP (x, 1));
4308 if (tem)
4309 return gen_binary (DIV, mode, tem, XEXP (XEXP (x, 0), 1));
4310 }
4311 break;
4312
4313 case UDIV:
4314 /* If this is a divide by a power of two, treat it as a shift if
4315 its first operand is a shift. */
4316 if (GET_CODE (XEXP (x, 1)) == CONST_INT
4317 && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0
4318 && (GET_CODE (XEXP (x, 0)) == ASHIFT
4319 || GET_CODE (XEXP (x, 0)) == LSHIFTRT
4320 || GET_CODE (XEXP (x, 0)) == ASHIFTRT
4321 || GET_CODE (XEXP (x, 0)) == ROTATE
4322 || GET_CODE (XEXP (x, 0)) == ROTATERT))
4323 return simplify_shift_const (NULL_RTX, LSHIFTRT, mode, XEXP (x, 0), i);
4324 break;
4325
4326 case EQ: case NE:
4327 case GT: case GTU: case GE: case GEU:
4328 case LT: case LTU: case LE: case LEU:
4329 case UNEQ: case LTGT:
4330 case UNGT: case UNGE:
4331 case UNLT: case UNLE:
4332 case UNORDERED: case ORDERED:
4333 /* If the first operand is a condition code, we can't do anything
4334 with it. */
4335 if (GET_CODE (XEXP (x, 0)) == COMPARE
4336 || (GET_MODE_CLASS (GET_MODE (XEXP (x, 0))) != MODE_CC
4337 && ! CC0_P (XEXP (x, 0))))
4338 {
4339 rtx op0 = XEXP (x, 0);
4340 rtx op1 = XEXP (x, 1);
4341 enum rtx_code new_code;
4342
4343 if (GET_CODE (op0) == COMPARE)
4344 op1 = XEXP (op0, 1), op0 = XEXP (op0, 0);
4345
4346 /* Simplify our comparison, if possible. */
4347 new_code = simplify_comparison (code, &op0, &op1);
4348
4349 /* If STORE_FLAG_VALUE is 1, we can convert (ne x 0) to simply X
4350 if only the low-order bit is possibly nonzero in X (such as when
4351 X is a ZERO_EXTRACT of one bit). Similarly, we can convert EQ to
4352 (xor X 1) or (minus 1 X); we use the former. Finally, if X is
4353 known to be either 0 or -1, NE becomes a NEG and EQ becomes
4354 (plus X 1).
4355
4356 Remove any ZERO_EXTRACT we made when thinking this was a
4357 comparison. It may now be simpler to use, e.g., an AND. If a
4358 ZERO_EXTRACT is indeed appropriate, it will be placed back by
4359 the call to make_compound_operation in the SET case. */
4360
4361 if (STORE_FLAG_VALUE == 1
4362 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
4363 && op1 == const0_rtx
4364 && mode == GET_MODE (op0)
4365 && nonzero_bits (op0, mode) == 1)
4366 return gen_lowpart_for_combine (mode,
4367 expand_compound_operation (op0));
4368
4369 else if (STORE_FLAG_VALUE == 1
4370 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
4371 && op1 == const0_rtx
4372 && mode == GET_MODE (op0)
4373 && (num_sign_bit_copies (op0, mode)
4374 == GET_MODE_BITSIZE (mode)))
4375 {
4376 op0 = expand_compound_operation (op0);
4377 return simplify_gen_unary (NEG, mode,
4378 gen_lowpart_for_combine (mode, op0),
4379 mode);
4380 }
4381
4382 else if (STORE_FLAG_VALUE == 1
4383 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT
4384 && op1 == const0_rtx
4385 && mode == GET_MODE (op0)
4386 && nonzero_bits (op0, mode) == 1)
4387 {
4388 op0 = expand_compound_operation (op0);
4389 return gen_binary (XOR, mode,
4390 gen_lowpart_for_combine (mode, op0),
4391 const1_rtx);
4392 }
4393
4394 else if (STORE_FLAG_VALUE == 1
4395 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT
4396 && op1 == const0_rtx
4397 && mode == GET_MODE (op0)
4398 && (num_sign_bit_copies (op0, mode)
4399 == GET_MODE_BITSIZE (mode)))
4400 {
4401 op0 = expand_compound_operation (op0);
4402 return plus_constant (gen_lowpart_for_combine (mode, op0), 1);
4403 }
4404
4405 /* If STORE_FLAG_VALUE is -1, we have cases similar to
4406 those above. */
4407 if (STORE_FLAG_VALUE == -1
4408 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
4409 && op1 == const0_rtx
4410 && (num_sign_bit_copies (op0, mode)
4411 == GET_MODE_BITSIZE (mode)))
4412 return gen_lowpart_for_combine (mode,
4413 expand_compound_operation (op0));
4414
4415 else if (STORE_FLAG_VALUE == -1
4416 && new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
4417 && op1 == const0_rtx
4418 && mode == GET_MODE (op0)
4419 && nonzero_bits (op0, mode) == 1)
4420 {
4421 op0 = expand_compound_operation (op0);
4422 return simplify_gen_unary (NEG, mode,
4423 gen_lowpart_for_combine (mode, op0),
4424 mode);
4425 }
4426
4427 else if (STORE_FLAG_VALUE == -1
4428 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT
4429 && op1 == const0_rtx
4430 && mode == GET_MODE (op0)
4431 && (num_sign_bit_copies (op0, mode)
4432 == GET_MODE_BITSIZE (mode)))
4433 {
4434 op0 = expand_compound_operation (op0);
4435 return simplify_gen_unary (NOT, mode,
4436 gen_lowpart_for_combine (mode, op0),
4437 mode);
4438 }
4439
4440 /* If X is 0/1, (eq X 0) is X-1. */
4441 else if (STORE_FLAG_VALUE == -1
4442 && new_code == EQ && GET_MODE_CLASS (mode) == MODE_INT
4443 && op1 == const0_rtx
4444 && mode == GET_MODE (op0)
4445 && nonzero_bits (op0, mode) == 1)
4446 {
4447 op0 = expand_compound_operation (op0);
4448 return plus_constant (gen_lowpart_for_combine (mode, op0), -1);
4449 }
4450
4451 /* If STORE_FLAG_VALUE says to just test the sign bit and X has just
4452 one bit that might be nonzero, we can convert (ne x 0) to
4453 (ashift x c) where C puts the bit in the sign bit. Remove any
4454 AND with STORE_FLAG_VALUE when we are done, since we are only
4455 going to test the sign bit. */
4456 if (new_code == NE && GET_MODE_CLASS (mode) == MODE_INT
4457 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4458 && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode))
4459 == (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1))
4460 && op1 == const0_rtx
4461 && mode == GET_MODE (op0)
4462 && (i = exact_log2 (nonzero_bits (op0, mode))) >= 0)
4463 {
4464 x = simplify_shift_const (NULL_RTX, ASHIFT, mode,
4465 expand_compound_operation (op0),
4466 GET_MODE_BITSIZE (mode) - 1 - i);
4467 if (GET_CODE (x) == AND && XEXP (x, 1) == const_true_rtx)
4468 return XEXP (x, 0);
4469 else
4470 return x;
4471 }
4472
4473 /* If the code changed, return a whole new comparison. */
4474 if (new_code != code)
4475 return gen_rtx_fmt_ee (new_code, mode, op0, op1);
4476
4477 /* Otherwise, keep this operation, but maybe change its operands.
4478 This also converts (ne (compare FOO BAR) 0) to (ne FOO BAR). */
4479 SUBST (XEXP (x, 0), op0);
4480 SUBST (XEXP (x, 1), op1);
4481 }
4482 break;
4483
4484 case IF_THEN_ELSE:
4485 return simplify_if_then_else (x);
4486
4487 case ZERO_EXTRACT:
4488 case SIGN_EXTRACT:
4489 case ZERO_EXTEND:
4490 case SIGN_EXTEND:
4491 /* If we are processing SET_DEST, we are done. */
4492 if (in_dest)
4493 return x;
4494
4495 return expand_compound_operation (x);
4496
4497 case SET:
4498 return simplify_set (x);
4499
4500 case AND:
4501 case IOR:
4502 case XOR:
4503 return simplify_logical (x, last);
4504
4505 case ABS:
4506 /* (abs (neg <foo>)) -> (abs <foo>) */
4507 if (GET_CODE (XEXP (x, 0)) == NEG)
4508 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4509
4510 /* If the mode of the operand is VOIDmode (i.e. if it is ASM_OPERANDS),
4511 do nothing. */
4512 if (GET_MODE (XEXP (x, 0)) == VOIDmode)
4513 break;
4514
4515 /* If operand is something known to be positive, ignore the ABS. */
4516 if (GET_CODE (XEXP (x, 0)) == FFS || GET_CODE (XEXP (x, 0)) == ABS
4517 || ((GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
4518 <= HOST_BITS_PER_WIDE_INT)
4519 && ((nonzero_bits (XEXP (x, 0), GET_MODE (XEXP (x, 0)))
4520 & ((HOST_WIDE_INT) 1
4521 << (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - 1)))
4522 == 0)))
4523 return XEXP (x, 0);
4524
4525 /* If operand is known to be only -1 or 0, convert ABS to NEG. */
4526 if (num_sign_bit_copies (XEXP (x, 0), mode) == GET_MODE_BITSIZE (mode))
4527 return gen_rtx_NEG (mode, XEXP (x, 0));
4528
4529 break;
4530
4531 case FFS:
4532 /* (ffs (*_extend <X>)) = (ffs <X>) */
4533 if (GET_CODE (XEXP (x, 0)) == SIGN_EXTEND
4534 || GET_CODE (XEXP (x, 0)) == ZERO_EXTEND)
4535 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4536 break;
4537
4538 case POPCOUNT:
4539 case PARITY:
4540 /* (pop* (zero_extend <X>)) = (pop* <X>) */
4541 if (GET_CODE (XEXP (x, 0)) == ZERO_EXTEND)
4542 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4543 break;
4544
4545 case FLOAT:
4546 /* (float (sign_extend <X>)) = (float <X>). */
4547 if (GET_CODE (XEXP (x, 0)) == SIGN_EXTEND)
4548 SUBST (XEXP (x, 0), XEXP (XEXP (x, 0), 0));
4549 break;
4550
4551 case ASHIFT:
4552 case LSHIFTRT:
4553 case ASHIFTRT:
4554 case ROTATE:
4555 case ROTATERT:
4556 /* If this is a shift by a constant amount, simplify it. */
4557 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
4558 return simplify_shift_const (x, code, mode, XEXP (x, 0),
4559 INTVAL (XEXP (x, 1)));
4560
4561 else if (SHIFT_COUNT_TRUNCATED && GET_CODE (XEXP (x, 1)) != REG)
4562 SUBST (XEXP (x, 1),
4563 force_to_mode (XEXP (x, 1), GET_MODE (XEXP (x, 1)),
4564 ((HOST_WIDE_INT) 1
4565 << exact_log2 (GET_MODE_BITSIZE (GET_MODE (x))))
4566 - 1,
4567 NULL_RTX, 0));
4568 break;
4569
4570 case VEC_SELECT:
4571 {
4572 rtx op0 = XEXP (x, 0);
4573 rtx op1 = XEXP (x, 1);
4574 int len;
4575
4576 if (GET_CODE (op1) != PARALLEL)
4577 abort ();
4578 len = XVECLEN (op1, 0);
4579 if (len == 1
4580 && GET_CODE (XVECEXP (op1, 0, 0)) == CONST_INT
4581 && GET_CODE (op0) == VEC_CONCAT)
4582 {
4583 int offset = INTVAL (XVECEXP (op1, 0, 0)) * GET_MODE_SIZE (GET_MODE (x));
4584
4585 /* Try to find the element in the VEC_CONCAT. */
4586 for (;;)
4587 {
4588 if (GET_MODE (op0) == GET_MODE (x))
4589 return op0;
4590 if (GET_CODE (op0) == VEC_CONCAT)
4591 {
4592 HOST_WIDE_INT op0_size = GET_MODE_SIZE (GET_MODE (XEXP (op0, 0)));
4593 if (op0_size < offset)
4594 op0 = XEXP (op0, 0);
4595 else
4596 {
4597 offset -= op0_size;
4598 op0 = XEXP (op0, 1);
4599 }
4600 }
4601 else
4602 break;
4603 }
4604 }
4605 }
4606
4607 break;
4608
4609 default:
4610 break;
4611 }
4612
4613 return x;
4614 }
4615
4616 /* Simplify X, an IF_THEN_ELSE expression. Return the new expression. */
4617
4618 static rtx
simplify_if_then_else(rtx x)4619 simplify_if_then_else (rtx x)
4620 {
4621 enum machine_mode mode = GET_MODE (x);
4622 rtx cond = XEXP (x, 0);
4623 rtx true_rtx = XEXP (x, 1);
4624 rtx false_rtx = XEXP (x, 2);
4625 enum rtx_code true_code = GET_CODE (cond);
4626 int comparison_p = GET_RTX_CLASS (true_code) == '<';
4627 rtx temp;
4628 int i;
4629 enum rtx_code false_code;
4630 rtx reversed;
4631
4632 /* Simplify storing of the truth value. */
4633 if (comparison_p && true_rtx == const_true_rtx && false_rtx == const0_rtx)
4634 return gen_binary (true_code, mode, XEXP (cond, 0), XEXP (cond, 1));
4635
4636 /* Also when the truth value has to be reversed. */
4637 if (comparison_p
4638 && true_rtx == const0_rtx && false_rtx == const_true_rtx
4639 && (reversed = reversed_comparison (cond, mode, XEXP (cond, 0),
4640 XEXP (cond, 1))))
4641 return reversed;
4642
4643 /* Sometimes we can simplify the arm of an IF_THEN_ELSE if a register used
4644 in it is being compared against certain values. Get the true and false
4645 comparisons and see if that says anything about the value of each arm. */
4646
4647 if (comparison_p
4648 && ((false_code = combine_reversed_comparison_code (cond))
4649 != UNKNOWN)
4650 && GET_CODE (XEXP (cond, 0)) == REG)
4651 {
4652 HOST_WIDE_INT nzb;
4653 rtx from = XEXP (cond, 0);
4654 rtx true_val = XEXP (cond, 1);
4655 rtx false_val = true_val;
4656 int swapped = 0;
4657
4658 /* If FALSE_CODE is EQ, swap the codes and arms. */
4659
4660 if (false_code == EQ)
4661 {
4662 swapped = 1, true_code = EQ, false_code = NE;
4663 temp = true_rtx, true_rtx = false_rtx, false_rtx = temp;
4664 }
4665
4666 /* If we are comparing against zero and the expression being tested has
4667 only a single bit that might be nonzero, that is its value when it is
4668 not equal to zero. Similarly if it is known to be -1 or 0. */
4669
4670 if (true_code == EQ && true_val == const0_rtx
4671 && exact_log2 (nzb = nonzero_bits (from, GET_MODE (from))) >= 0)
4672 false_code = EQ, false_val = GEN_INT (nzb);
4673 else if (true_code == EQ && true_val == const0_rtx
4674 && (num_sign_bit_copies (from, GET_MODE (from))
4675 == GET_MODE_BITSIZE (GET_MODE (from))))
4676 false_code = EQ, false_val = constm1_rtx;
4677
4678 /* Now simplify an arm if we know the value of the register in the
4679 branch and it is used in the arm. Be careful due to the potential
4680 of locally-shared RTL. */
4681
4682 if (reg_mentioned_p (from, true_rtx))
4683 true_rtx = subst (known_cond (copy_rtx (true_rtx), true_code,
4684 from, true_val),
4685 pc_rtx, pc_rtx, 0, 0);
4686 if (reg_mentioned_p (from, false_rtx))
4687 false_rtx = subst (known_cond (copy_rtx (false_rtx), false_code,
4688 from, false_val),
4689 pc_rtx, pc_rtx, 0, 0);
4690
4691 SUBST (XEXP (x, 1), swapped ? false_rtx : true_rtx);
4692 SUBST (XEXP (x, 2), swapped ? true_rtx : false_rtx);
4693
4694 true_rtx = XEXP (x, 1);
4695 false_rtx = XEXP (x, 2);
4696 true_code = GET_CODE (cond);
4697 }
4698
4699 /* If we have (if_then_else FOO (pc) (label_ref BAR)) and FOO can be
4700 reversed, do so to avoid needing two sets of patterns for
4701 subtract-and-branch insns. Similarly if we have a constant in the true
4702 arm, the false arm is the same as the first operand of the comparison, or
4703 the false arm is more complicated than the true arm. */
4704
4705 if (comparison_p
4706 && combine_reversed_comparison_code (cond) != UNKNOWN
4707 && (true_rtx == pc_rtx
4708 || (CONSTANT_P (true_rtx)
4709 && GET_CODE (false_rtx) != CONST_INT && false_rtx != pc_rtx)
4710 || true_rtx == const0_rtx
4711 || (GET_RTX_CLASS (GET_CODE (true_rtx)) == 'o'
4712 && GET_RTX_CLASS (GET_CODE (false_rtx)) != 'o')
4713 || (GET_CODE (true_rtx) == SUBREG
4714 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (true_rtx))) == 'o'
4715 && GET_RTX_CLASS (GET_CODE (false_rtx)) != 'o')
4716 || reg_mentioned_p (true_rtx, false_rtx)
4717 || rtx_equal_p (false_rtx, XEXP (cond, 0))))
4718 {
4719 true_code = reversed_comparison_code (cond, NULL);
4720 SUBST (XEXP (x, 0),
4721 reversed_comparison (cond, GET_MODE (cond), XEXP (cond, 0),
4722 XEXP (cond, 1)));
4723
4724 SUBST (XEXP (x, 1), false_rtx);
4725 SUBST (XEXP (x, 2), true_rtx);
4726
4727 temp = true_rtx, true_rtx = false_rtx, false_rtx = temp;
4728 cond = XEXP (x, 0);
4729
4730 /* It is possible that the conditional has been simplified out. */
4731 true_code = GET_CODE (cond);
4732 comparison_p = GET_RTX_CLASS (true_code) == '<';
4733 }
4734
4735 /* If the two arms are identical, we don't need the comparison. */
4736
4737 if (rtx_equal_p (true_rtx, false_rtx) && ! side_effects_p (cond))
4738 return true_rtx;
4739
4740 /* Convert a == b ? b : a to "a". */
4741 if (true_code == EQ && ! side_effects_p (cond)
4742 && !HONOR_NANS (mode)
4743 && rtx_equal_p (XEXP (cond, 0), false_rtx)
4744 && rtx_equal_p (XEXP (cond, 1), true_rtx))
4745 return false_rtx;
4746 else if (true_code == NE && ! side_effects_p (cond)
4747 && !HONOR_NANS (mode)
4748 && rtx_equal_p (XEXP (cond, 0), true_rtx)
4749 && rtx_equal_p (XEXP (cond, 1), false_rtx))
4750 return true_rtx;
4751
4752 /* Look for cases where we have (abs x) or (neg (abs X)). */
4753
4754 if (GET_MODE_CLASS (mode) == MODE_INT
4755 && GET_CODE (false_rtx) == NEG
4756 && rtx_equal_p (true_rtx, XEXP (false_rtx, 0))
4757 && comparison_p
4758 && rtx_equal_p (true_rtx, XEXP (cond, 0))
4759 && ! side_effects_p (true_rtx))
4760 switch (true_code)
4761 {
4762 case GT:
4763 case GE:
4764 return simplify_gen_unary (ABS, mode, true_rtx, mode);
4765 case LT:
4766 case LE:
4767 return
4768 simplify_gen_unary (NEG, mode,
4769 simplify_gen_unary (ABS, mode, true_rtx, mode),
4770 mode);
4771 default:
4772 break;
4773 }
4774
4775 /* Look for MIN or MAX. */
4776
4777 if ((! FLOAT_MODE_P (mode) || flag_unsafe_math_optimizations)
4778 && comparison_p
4779 && rtx_equal_p (XEXP (cond, 0), true_rtx)
4780 && rtx_equal_p (XEXP (cond, 1), false_rtx)
4781 && ! side_effects_p (cond))
4782 switch (true_code)
4783 {
4784 case GE:
4785 case GT:
4786 return gen_binary (SMAX, mode, true_rtx, false_rtx);
4787 case LE:
4788 case LT:
4789 return gen_binary (SMIN, mode, true_rtx, false_rtx);
4790 case GEU:
4791 case GTU:
4792 return gen_binary (UMAX, mode, true_rtx, false_rtx);
4793 case LEU:
4794 case LTU:
4795 return gen_binary (UMIN, mode, true_rtx, false_rtx);
4796 default:
4797 break;
4798 }
4799
4800 /* If we have (if_then_else COND (OP Z C1) Z) and OP is an identity when its
4801 second operand is zero, this can be done as (OP Z (mult COND C2)) where
4802 C2 = C1 * STORE_FLAG_VALUE. Similarly if OP has an outer ZERO_EXTEND or
4803 SIGN_EXTEND as long as Z is already extended (so we don't destroy it).
4804 We can do this kind of thing in some cases when STORE_FLAG_VALUE is
4805 neither 1 or -1, but it isn't worth checking for. */
4806
4807 if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
4808 && comparison_p
4809 && GET_MODE_CLASS (mode) == MODE_INT
4810 && ! side_effects_p (x))
4811 {
4812 rtx t = make_compound_operation (true_rtx, SET);
4813 rtx f = make_compound_operation (false_rtx, SET);
4814 rtx cond_op0 = XEXP (cond, 0);
4815 rtx cond_op1 = XEXP (cond, 1);
4816 enum rtx_code op = NIL, extend_op = NIL;
4817 enum machine_mode m = mode;
4818 rtx z = 0, c1 = NULL_RTX;
4819
4820 if ((GET_CODE (t) == PLUS || GET_CODE (t) == MINUS
4821 || GET_CODE (t) == IOR || GET_CODE (t) == XOR
4822 || GET_CODE (t) == ASHIFT
4823 || GET_CODE (t) == LSHIFTRT || GET_CODE (t) == ASHIFTRT)
4824 && rtx_equal_p (XEXP (t, 0), f))
4825 c1 = XEXP (t, 1), op = GET_CODE (t), z = f;
4826
4827 /* If an identity-zero op is commutative, check whether there
4828 would be a match if we swapped the operands. */
4829 else if ((GET_CODE (t) == PLUS || GET_CODE (t) == IOR
4830 || GET_CODE (t) == XOR)
4831 && rtx_equal_p (XEXP (t, 1), f))
4832 c1 = XEXP (t, 0), op = GET_CODE (t), z = f;
4833 else if (GET_CODE (t) == SIGN_EXTEND
4834 && (GET_CODE (XEXP (t, 0)) == PLUS
4835 || GET_CODE (XEXP (t, 0)) == MINUS
4836 || GET_CODE (XEXP (t, 0)) == IOR
4837 || GET_CODE (XEXP (t, 0)) == XOR
4838 || GET_CODE (XEXP (t, 0)) == ASHIFT
4839 || GET_CODE (XEXP (t, 0)) == LSHIFTRT
4840 || GET_CODE (XEXP (t, 0)) == ASHIFTRT)
4841 && GET_CODE (XEXP (XEXP (t, 0), 0)) == SUBREG
4842 && subreg_lowpart_p (XEXP (XEXP (t, 0), 0))
4843 && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 0)), f)
4844 && (num_sign_bit_copies (f, GET_MODE (f))
4845 > (unsigned int)
4846 (GET_MODE_BITSIZE (mode)
4847 - GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (t, 0), 0))))))
4848 {
4849 c1 = XEXP (XEXP (t, 0), 1); z = f; op = GET_CODE (XEXP (t, 0));
4850 extend_op = SIGN_EXTEND;
4851 m = GET_MODE (XEXP (t, 0));
4852 }
4853 else if (GET_CODE (t) == SIGN_EXTEND
4854 && (GET_CODE (XEXP (t, 0)) == PLUS
4855 || GET_CODE (XEXP (t, 0)) == IOR
4856 || GET_CODE (XEXP (t, 0)) == XOR)
4857 && GET_CODE (XEXP (XEXP (t, 0), 1)) == SUBREG
4858 && subreg_lowpart_p (XEXP (XEXP (t, 0), 1))
4859 && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 1)), f)
4860 && (num_sign_bit_copies (f, GET_MODE (f))
4861 > (unsigned int)
4862 (GET_MODE_BITSIZE (mode)
4863 - GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (t, 0), 1))))))
4864 {
4865 c1 = XEXP (XEXP (t, 0), 0); z = f; op = GET_CODE (XEXP (t, 0));
4866 extend_op = SIGN_EXTEND;
4867 m = GET_MODE (XEXP (t, 0));
4868 }
4869 else if (GET_CODE (t) == ZERO_EXTEND
4870 && (GET_CODE (XEXP (t, 0)) == PLUS
4871 || GET_CODE (XEXP (t, 0)) == MINUS
4872 || GET_CODE (XEXP (t, 0)) == IOR
4873 || GET_CODE (XEXP (t, 0)) == XOR
4874 || GET_CODE (XEXP (t, 0)) == ASHIFT
4875 || GET_CODE (XEXP (t, 0)) == LSHIFTRT
4876 || GET_CODE (XEXP (t, 0)) == ASHIFTRT)
4877 && GET_CODE (XEXP (XEXP (t, 0), 0)) == SUBREG
4878 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4879 && subreg_lowpart_p (XEXP (XEXP (t, 0), 0))
4880 && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 0)), f)
4881 && ((nonzero_bits (f, GET_MODE (f))
4882 & ~GET_MODE_MASK (GET_MODE (XEXP (XEXP (t, 0), 0))))
4883 == 0))
4884 {
4885 c1 = XEXP (XEXP (t, 0), 1); z = f; op = GET_CODE (XEXP (t, 0));
4886 extend_op = ZERO_EXTEND;
4887 m = GET_MODE (XEXP (t, 0));
4888 }
4889 else if (GET_CODE (t) == ZERO_EXTEND
4890 && (GET_CODE (XEXP (t, 0)) == PLUS
4891 || GET_CODE (XEXP (t, 0)) == IOR
4892 || GET_CODE (XEXP (t, 0)) == XOR)
4893 && GET_CODE (XEXP (XEXP (t, 0), 1)) == SUBREG
4894 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
4895 && subreg_lowpart_p (XEXP (XEXP (t, 0), 1))
4896 && rtx_equal_p (SUBREG_REG (XEXP (XEXP (t, 0), 1)), f)
4897 && ((nonzero_bits (f, GET_MODE (f))
4898 & ~GET_MODE_MASK (GET_MODE (XEXP (XEXP (t, 0), 1))))
4899 == 0))
4900 {
4901 c1 = XEXP (XEXP (t, 0), 0); z = f; op = GET_CODE (XEXP (t, 0));
4902 extend_op = ZERO_EXTEND;
4903 m = GET_MODE (XEXP (t, 0));
4904 }
4905
4906 if (z)
4907 {
4908 temp = subst (gen_binary (true_code, m, cond_op0, cond_op1),
4909 pc_rtx, pc_rtx, 0, 0);
4910 temp = gen_binary (MULT, m, temp,
4911 gen_binary (MULT, m, c1, const_true_rtx));
4912 temp = subst (temp, pc_rtx, pc_rtx, 0, 0);
4913 temp = gen_binary (op, m, gen_lowpart_for_combine (m, z), temp);
4914
4915 if (extend_op != NIL)
4916 temp = simplify_gen_unary (extend_op, mode, temp, m);
4917
4918 return temp;
4919 }
4920 }
4921
4922 /* If we have (if_then_else (ne A 0) C1 0) and either A is known to be 0 or
4923 1 and C1 is a single bit or A is known to be 0 or -1 and C1 is the
4924 negation of a single bit, we can convert this operation to a shift. We
4925 can actually do this more generally, but it doesn't seem worth it. */
4926
4927 if (true_code == NE && XEXP (cond, 1) == const0_rtx
4928 && false_rtx == const0_rtx && GET_CODE (true_rtx) == CONST_INT
4929 && ((1 == nonzero_bits (XEXP (cond, 0), mode)
4930 && (i = exact_log2 (INTVAL (true_rtx))) >= 0)
4931 || ((num_sign_bit_copies (XEXP (cond, 0), mode)
4932 == GET_MODE_BITSIZE (mode))
4933 && (i = exact_log2 (-INTVAL (true_rtx))) >= 0)))
4934 return
4935 simplify_shift_const (NULL_RTX, ASHIFT, mode,
4936 gen_lowpart_for_combine (mode, XEXP (cond, 0)), i);
4937
4938 /* (IF_THEN_ELSE (NE REG 0) (0) (8)) is REG for nonzero_bits (REG) == 8. */
4939 if (true_code == NE && XEXP (cond, 1) == const0_rtx
4940 && false_rtx == const0_rtx && GET_CODE (true_rtx) == CONST_INT
4941 && GET_MODE (XEXP (cond, 0)) == mode
4942 && (INTVAL (true_rtx) & GET_MODE_MASK (mode))
4943 == nonzero_bits (XEXP (cond, 0), mode)
4944 && (i = exact_log2 (INTVAL (true_rtx) & GET_MODE_MASK (mode))) >= 0)
4945 return XEXP (cond, 0);
4946
4947 return x;
4948 }
4949
4950 /* Simplify X, a SET expression. Return the new expression. */
4951
4952 static rtx
simplify_set(rtx x)4953 simplify_set (rtx x)
4954 {
4955 rtx src = SET_SRC (x);
4956 rtx dest = SET_DEST (x);
4957 enum machine_mode mode
4958 = GET_MODE (src) != VOIDmode ? GET_MODE (src) : GET_MODE (dest);
4959 rtx other_insn;
4960 rtx *cc_use;
4961
4962 /* (set (pc) (return)) gets written as (return). */
4963 if (GET_CODE (dest) == PC && GET_CODE (src) == RETURN)
4964 return src;
4965
4966 /* Now that we know for sure which bits of SRC we are using, see if we can
4967 simplify the expression for the object knowing that we only need the
4968 low-order bits. */
4969
4970 if (GET_MODE_CLASS (mode) == MODE_INT
4971 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
4972 {
4973 src = force_to_mode (src, mode, ~(HOST_WIDE_INT) 0, NULL_RTX, 0);
4974 SUBST (SET_SRC (x), src);
4975 }
4976
4977 /* If we are setting CC0 or if the source is a COMPARE, look for the use of
4978 the comparison result and try to simplify it unless we already have used
4979 undobuf.other_insn. */
4980 if ((GET_MODE_CLASS (mode) == MODE_CC
4981 || GET_CODE (src) == COMPARE
4982 || CC0_P (dest))
4983 && (cc_use = find_single_use (dest, subst_insn, &other_insn)) != 0
4984 && (undobuf.other_insn == 0 || other_insn == undobuf.other_insn)
4985 && GET_RTX_CLASS (GET_CODE (*cc_use)) == '<'
4986 && rtx_equal_p (XEXP (*cc_use, 0), dest))
4987 {
4988 enum rtx_code old_code = GET_CODE (*cc_use);
4989 enum rtx_code new_code;
4990 rtx op0, op1, tmp;
4991 int other_changed = 0;
4992 enum machine_mode compare_mode = GET_MODE (dest);
4993 enum machine_mode tmp_mode;
4994
4995 if (GET_CODE (src) == COMPARE)
4996 op0 = XEXP (src, 0), op1 = XEXP (src, 1);
4997 else
4998 op0 = src, op1 = const0_rtx;
4999
5000 /* Check whether the comparison is known at compile time. */
5001 if (GET_MODE (op0) != VOIDmode)
5002 tmp_mode = GET_MODE (op0);
5003 else if (GET_MODE (op1) != VOIDmode)
5004 tmp_mode = GET_MODE (op1);
5005 else
5006 tmp_mode = compare_mode;
5007 tmp = simplify_relational_operation (old_code, tmp_mode, op0, op1);
5008 if (tmp != NULL_RTX)
5009 {
5010 rtx pat = PATTERN (other_insn);
5011 undobuf.other_insn = other_insn;
5012 SUBST (*cc_use, tmp);
5013
5014 /* Attempt to simplify CC user. */
5015 if (GET_CODE (pat) == SET)
5016 {
5017 rtx new = simplify_rtx (SET_SRC (pat));
5018 if (new != NULL_RTX)
5019 SUBST (SET_SRC (pat), new);
5020 }
5021
5022 /* Convert X into a no-op move. */
5023 SUBST (SET_DEST (x), pc_rtx);
5024 SUBST (SET_SRC (x), pc_rtx);
5025 return x;
5026 }
5027
5028 /* Simplify our comparison, if possible. */
5029 new_code = simplify_comparison (old_code, &op0, &op1);
5030
5031 #ifdef SELECT_CC_MODE
5032 /* If this machine has CC modes other than CCmode, check to see if we
5033 need to use a different CC mode here. */
5034 compare_mode = SELECT_CC_MODE (new_code, op0, op1);
5035
5036 #ifndef HAVE_cc0
5037 /* If the mode changed, we have to change SET_DEST, the mode in the
5038 compare, and the mode in the place SET_DEST is used. If SET_DEST is
5039 a hard register, just build new versions with the proper mode. If it
5040 is a pseudo, we lose unless it is only time we set the pseudo, in
5041 which case we can safely change its mode. */
5042 if (compare_mode != GET_MODE (dest))
5043 {
5044 unsigned int regno = REGNO (dest);
5045 rtx new_dest = gen_rtx_REG (compare_mode, regno);
5046
5047 if (regno < FIRST_PSEUDO_REGISTER
5048 || (REG_N_SETS (regno) == 1 && ! REG_USERVAR_P (dest)))
5049 {
5050 if (regno >= FIRST_PSEUDO_REGISTER)
5051 SUBST (regno_reg_rtx[regno], new_dest);
5052
5053 SUBST (SET_DEST (x), new_dest);
5054 SUBST (XEXP (*cc_use, 0), new_dest);
5055 other_changed = 1;
5056
5057 dest = new_dest;
5058 }
5059 }
5060 #endif /* cc0 */
5061 #endif /* SELECT_CC_MODE */
5062
5063 /* If the code changed, we have to build a new comparison in
5064 undobuf.other_insn. */
5065 if (new_code != old_code)
5066 {
5067 int other_changed_previously = other_changed;
5068 unsigned HOST_WIDE_INT mask;
5069
5070 SUBST (*cc_use, gen_rtx_fmt_ee (new_code, GET_MODE (*cc_use),
5071 dest, const0_rtx));
5072 other_changed = 1;
5073
5074 /* If the only change we made was to change an EQ into an NE or
5075 vice versa, OP0 has only one bit that might be nonzero, and OP1
5076 is zero, check if changing the user of the condition code will
5077 produce a valid insn. If it won't, we can keep the original code
5078 in that insn by surrounding our operation with an XOR. */
5079
5080 if (((old_code == NE && new_code == EQ)
5081 || (old_code == EQ && new_code == NE))
5082 && ! other_changed_previously && op1 == const0_rtx
5083 && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT
5084 && exact_log2 (mask = nonzero_bits (op0, GET_MODE (op0))) >= 0)
5085 {
5086 rtx pat = PATTERN (other_insn), note = 0;
5087
5088 if ((recog_for_combine (&pat, other_insn, ¬e) < 0
5089 && ! check_asm_operands (pat)))
5090 {
5091 PUT_CODE (*cc_use, old_code);
5092 other_changed = 0;
5093
5094 op0 = gen_binary (XOR, GET_MODE (op0), op0, GEN_INT (mask));
5095 }
5096 }
5097 }
5098
5099 if (other_changed)
5100 undobuf.other_insn = other_insn;
5101
5102 #ifdef HAVE_cc0
5103 /* If we are now comparing against zero, change our source if
5104 needed. If we do not use cc0, we always have a COMPARE. */
5105 if (op1 == const0_rtx && dest == cc0_rtx)
5106 {
5107 SUBST (SET_SRC (x), op0);
5108 src = op0;
5109 }
5110 else
5111 #endif
5112
5113 /* Otherwise, if we didn't previously have a COMPARE in the
5114 correct mode, we need one. */
5115 if (GET_CODE (src) != COMPARE || GET_MODE (src) != compare_mode)
5116 {
5117 SUBST (SET_SRC (x), gen_rtx_COMPARE (compare_mode, op0, op1));
5118 src = SET_SRC (x);
5119 }
5120 else
5121 {
5122 /* Otherwise, update the COMPARE if needed. */
5123 SUBST (XEXP (src, 0), op0);
5124 SUBST (XEXP (src, 1), op1);
5125 }
5126 }
5127 else
5128 {
5129 /* Get SET_SRC in a form where we have placed back any
5130 compound expressions. Then do the checks below. */
5131 src = make_compound_operation (src, SET);
5132 SUBST (SET_SRC (x), src);
5133 }
5134
5135 /* If we have (set x (subreg:m1 (op:m2 ...) 0)) with OP being some operation,
5136 and X being a REG or (subreg (reg)), we may be able to convert this to
5137 (set (subreg:m2 x) (op)).
5138
5139 We can always do this if M1 is narrower than M2 because that means that
5140 we only care about the low bits of the result.
5141
5142 However, on machines without WORD_REGISTER_OPERATIONS defined, we cannot
5143 perform a narrower operation than requested since the high-order bits will
5144 be undefined. On machine where it is defined, this transformation is safe
5145 as long as M1 and M2 have the same number of words. */
5146
5147 if (GET_CODE (src) == SUBREG && subreg_lowpart_p (src)
5148 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (src))) != 'o'
5149 && (((GET_MODE_SIZE (GET_MODE (src)) + (UNITS_PER_WORD - 1))
5150 / UNITS_PER_WORD)
5151 == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))
5152 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))
5153 #ifndef WORD_REGISTER_OPERATIONS
5154 && (GET_MODE_SIZE (GET_MODE (src))
5155 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))))
5156 #endif
5157 #ifdef CANNOT_CHANGE_MODE_CLASS
5158 && ! (GET_CODE (dest) == REG && REGNO (dest) < FIRST_PSEUDO_REGISTER
5159 && REG_CANNOT_CHANGE_MODE_P (REGNO (dest),
5160 GET_MODE (SUBREG_REG (src)),
5161 GET_MODE (src)))
5162 #endif
5163 && (GET_CODE (dest) == REG
5164 || (GET_CODE (dest) == SUBREG
5165 && GET_CODE (SUBREG_REG (dest)) == REG)))
5166 {
5167 SUBST (SET_DEST (x),
5168 gen_lowpart_for_combine (GET_MODE (SUBREG_REG (src)),
5169 dest));
5170 SUBST (SET_SRC (x), SUBREG_REG (src));
5171
5172 src = SET_SRC (x), dest = SET_DEST (x);
5173 }
5174
5175 #ifdef HAVE_cc0
5176 /* If we have (set (cc0) (subreg ...)), we try to remove the subreg
5177 in SRC. */
5178 if (dest == cc0_rtx
5179 && GET_CODE (src) == SUBREG
5180 && subreg_lowpart_p (src)
5181 && (GET_MODE_BITSIZE (GET_MODE (src))
5182 < GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (src)))))
5183 {
5184 rtx inner = SUBREG_REG (src);
5185 enum machine_mode inner_mode = GET_MODE (inner);
5186
5187 /* Here we make sure that we don't have a sign bit on. */
5188 if (GET_MODE_BITSIZE (inner_mode) <= HOST_BITS_PER_WIDE_INT
5189 && (nonzero_bits (inner, inner_mode)
5190 < ((unsigned HOST_WIDE_INT) 1
5191 << (GET_MODE_BITSIZE (GET_MODE (src)) - 1))))
5192 {
5193 SUBST (SET_SRC (x), inner);
5194 src = SET_SRC (x);
5195 }
5196 }
5197 #endif
5198
5199 #ifdef LOAD_EXTEND_OP
5200 /* If we have (set FOO (subreg:M (mem:N BAR) 0)) with M wider than N, this
5201 would require a paradoxical subreg. Replace the subreg with a
5202 zero_extend to avoid the reload that would otherwise be required. */
5203
5204 if (GET_CODE (src) == SUBREG && subreg_lowpart_p (src)
5205 && LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (src))) != NIL
5206 && SUBREG_BYTE (src) == 0
5207 && (GET_MODE_SIZE (GET_MODE (src))
5208 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))))
5209 && GET_CODE (SUBREG_REG (src)) == MEM)
5210 {
5211 SUBST (SET_SRC (x),
5212 gen_rtx (LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (src))),
5213 GET_MODE (src), SUBREG_REG (src)));
5214
5215 src = SET_SRC (x);
5216 }
5217 #endif
5218
5219 /* If we don't have a conditional move, SET_SRC is an IF_THEN_ELSE, and we
5220 are comparing an item known to be 0 or -1 against 0, use a logical
5221 operation instead. Check for one of the arms being an IOR of the other
5222 arm with some value. We compute three terms to be IOR'ed together. In
5223 practice, at most two will be nonzero. Then we do the IOR's. */
5224
5225 if (GET_CODE (dest) != PC
5226 && GET_CODE (src) == IF_THEN_ELSE
5227 && GET_MODE_CLASS (GET_MODE (src)) == MODE_INT
5228 && (GET_CODE (XEXP (src, 0)) == EQ || GET_CODE (XEXP (src, 0)) == NE)
5229 && XEXP (XEXP (src, 0), 1) == const0_rtx
5230 && GET_MODE (src) == GET_MODE (XEXP (XEXP (src, 0), 0))
5231 #ifdef HAVE_conditional_move
5232 && ! can_conditionally_move_p (GET_MODE (src))
5233 #endif
5234 && (num_sign_bit_copies (XEXP (XEXP (src, 0), 0),
5235 GET_MODE (XEXP (XEXP (src, 0), 0)))
5236 == GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (src, 0), 0))))
5237 && ! side_effects_p (src))
5238 {
5239 rtx true_rtx = (GET_CODE (XEXP (src, 0)) == NE
5240 ? XEXP (src, 1) : XEXP (src, 2));
5241 rtx false_rtx = (GET_CODE (XEXP (src, 0)) == NE
5242 ? XEXP (src, 2) : XEXP (src, 1));
5243 rtx term1 = const0_rtx, term2, term3;
5244
5245 if (GET_CODE (true_rtx) == IOR
5246 && rtx_equal_p (XEXP (true_rtx, 0), false_rtx))
5247 term1 = false_rtx, true_rtx = XEXP (true_rtx, 1), false_rtx = const0_rtx;
5248 else if (GET_CODE (true_rtx) == IOR
5249 && rtx_equal_p (XEXP (true_rtx, 1), false_rtx))
5250 term1 = false_rtx, true_rtx = XEXP (true_rtx, 0), false_rtx = const0_rtx;
5251 else if (GET_CODE (false_rtx) == IOR
5252 && rtx_equal_p (XEXP (false_rtx, 0), true_rtx))
5253 term1 = true_rtx, false_rtx = XEXP (false_rtx, 1), true_rtx = const0_rtx;
5254 else if (GET_CODE (false_rtx) == IOR
5255 && rtx_equal_p (XEXP (false_rtx, 1), true_rtx))
5256 term1 = true_rtx, false_rtx = XEXP (false_rtx, 0), true_rtx = const0_rtx;
5257
5258 term2 = gen_binary (AND, GET_MODE (src),
5259 XEXP (XEXP (src, 0), 0), true_rtx);
5260 term3 = gen_binary (AND, GET_MODE (src),
5261 simplify_gen_unary (NOT, GET_MODE (src),
5262 XEXP (XEXP (src, 0), 0),
5263 GET_MODE (src)),
5264 false_rtx);
5265
5266 SUBST (SET_SRC (x),
5267 gen_binary (IOR, GET_MODE (src),
5268 gen_binary (IOR, GET_MODE (src), term1, term2),
5269 term3));
5270
5271 src = SET_SRC (x);
5272 }
5273
5274 /* If either SRC or DEST is a CLOBBER of (const_int 0), make this
5275 whole thing fail. */
5276 if (GET_CODE (src) == CLOBBER && XEXP (src, 0) == const0_rtx)
5277 return src;
5278 else if (GET_CODE (dest) == CLOBBER && XEXP (dest, 0) == const0_rtx)
5279 return dest;
5280 else
5281 /* Convert this into a field assignment operation, if possible. */
5282 return make_field_assignment (x);
5283 }
5284
5285 /* Simplify, X, and AND, IOR, or XOR operation, and return the simplified
5286 result. LAST is nonzero if this is the last retry. */
5287
5288 static rtx
simplify_logical(rtx x,int last)5289 simplify_logical (rtx x, int last)
5290 {
5291 enum machine_mode mode = GET_MODE (x);
5292 rtx op0 = XEXP (x, 0);
5293 rtx op1 = XEXP (x, 1);
5294 rtx reversed;
5295
5296 switch (GET_CODE (x))
5297 {
5298 case AND:
5299 /* Convert (A ^ B) & A to A & (~B) since the latter is often a single
5300 insn (and may simplify more). */
5301 if (GET_CODE (op0) == XOR
5302 && rtx_equal_p (XEXP (op0, 0), op1)
5303 && ! side_effects_p (op1))
5304 x = gen_binary (AND, mode,
5305 simplify_gen_unary (NOT, mode, XEXP (op0, 1), mode),
5306 op1);
5307
5308 if (GET_CODE (op0) == XOR
5309 && rtx_equal_p (XEXP (op0, 1), op1)
5310 && ! side_effects_p (op1))
5311 x = gen_binary (AND, mode,
5312 simplify_gen_unary (NOT, mode, XEXP (op0, 0), mode),
5313 op1);
5314
5315 /* Similarly for (~(A ^ B)) & A. */
5316 if (GET_CODE (op0) == NOT
5317 && GET_CODE (XEXP (op0, 0)) == XOR
5318 && rtx_equal_p (XEXP (XEXP (op0, 0), 0), op1)
5319 && ! side_effects_p (op1))
5320 x = gen_binary (AND, mode, XEXP (XEXP (op0, 0), 1), op1);
5321
5322 if (GET_CODE (op0) == NOT
5323 && GET_CODE (XEXP (op0, 0)) == XOR
5324 && rtx_equal_p (XEXP (XEXP (op0, 0), 1), op1)
5325 && ! side_effects_p (op1))
5326 x = gen_binary (AND, mode, XEXP (XEXP (op0, 0), 0), op1);
5327
5328 /* We can call simplify_and_const_int only if we don't lose
5329 any (sign) bits when converting INTVAL (op1) to
5330 "unsigned HOST_WIDE_INT". */
5331 if (GET_CODE (op1) == CONST_INT
5332 && (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
5333 || INTVAL (op1) > 0))
5334 {
5335 x = simplify_and_const_int (x, mode, op0, INTVAL (op1));
5336
5337 /* If we have (ior (and (X C1) C2)) and the next restart would be
5338 the last, simplify this by making C1 as small as possible
5339 and then exit. */
5340 if (last
5341 && GET_CODE (x) == IOR && GET_CODE (op0) == AND
5342 && GET_CODE (XEXP (op0, 1)) == CONST_INT
5343 && GET_CODE (op1) == CONST_INT)
5344 return gen_binary (IOR, mode,
5345 gen_binary (AND, mode, XEXP (op0, 0),
5346 GEN_INT (INTVAL (XEXP (op0, 1))
5347 & ~INTVAL (op1))), op1);
5348
5349 if (GET_CODE (x) != AND)
5350 return x;
5351
5352 if (GET_RTX_CLASS (GET_CODE (x)) == 'c'
5353 || GET_RTX_CLASS (GET_CODE (x)) == '2')
5354 op0 = XEXP (x, 0), op1 = XEXP (x, 1);
5355 }
5356
5357 /* Convert (A | B) & A to A. */
5358 if (GET_CODE (op0) == IOR
5359 && (rtx_equal_p (XEXP (op0, 0), op1)
5360 || rtx_equal_p (XEXP (op0, 1), op1))
5361 && ! side_effects_p (XEXP (op0, 0))
5362 && ! side_effects_p (XEXP (op0, 1)))
5363 return op1;
5364
5365 /* In the following group of tests (and those in case IOR below),
5366 we start with some combination of logical operations and apply
5367 the distributive law followed by the inverse distributive law.
5368 Most of the time, this results in no change. However, if some of
5369 the operands are the same or inverses of each other, simplifications
5370 will result.
5371
5372 For example, (and (ior A B) (not B)) can occur as the result of
5373 expanding a bit field assignment. When we apply the distributive
5374 law to this, we get (ior (and (A (not B))) (and (B (not B)))),
5375 which then simplifies to (and (A (not B))).
5376
5377 If we have (and (ior A B) C), apply the distributive law and then
5378 the inverse distributive law to see if things simplify. */
5379
5380 if (GET_CODE (op0) == IOR || GET_CODE (op0) == XOR)
5381 {
5382 x = apply_distributive_law
5383 (gen_binary (GET_CODE (op0), mode,
5384 gen_binary (AND, mode, XEXP (op0, 0), op1),
5385 gen_binary (AND, mode, XEXP (op0, 1),
5386 copy_rtx (op1))));
5387 if (GET_CODE (x) != AND)
5388 return x;
5389 }
5390
5391 if (GET_CODE (op1) == IOR || GET_CODE (op1) == XOR)
5392 return apply_distributive_law
5393 (gen_binary (GET_CODE (op1), mode,
5394 gen_binary (AND, mode, XEXP (op1, 0), op0),
5395 gen_binary (AND, mode, XEXP (op1, 1),
5396 copy_rtx (op0))));
5397
5398 /* Similarly, taking advantage of the fact that
5399 (and (not A) (xor B C)) == (xor (ior A B) (ior A C)) */
5400
5401 if (GET_CODE (op0) == NOT && GET_CODE (op1) == XOR)
5402 return apply_distributive_law
5403 (gen_binary (XOR, mode,
5404 gen_binary (IOR, mode, XEXP (op0, 0), XEXP (op1, 0)),
5405 gen_binary (IOR, mode, copy_rtx (XEXP (op0, 0)),
5406 XEXP (op1, 1))));
5407
5408 else if (GET_CODE (op1) == NOT && GET_CODE (op0) == XOR)
5409 return apply_distributive_law
5410 (gen_binary (XOR, mode,
5411 gen_binary (IOR, mode, XEXP (op1, 0), XEXP (op0, 0)),
5412 gen_binary (IOR, mode, copy_rtx (XEXP (op1, 0)), XEXP (op0, 1))));
5413 break;
5414
5415 case IOR:
5416 /* (ior A C) is C if all bits of A that might be nonzero are on in C. */
5417 if (GET_CODE (op1) == CONST_INT
5418 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
5419 && (nonzero_bits (op0, mode) & ~INTVAL (op1)) == 0)
5420 return op1;
5421
5422 /* Convert (A & B) | A to A. */
5423 if (GET_CODE (op0) == AND
5424 && (rtx_equal_p (XEXP (op0, 0), op1)
5425 || rtx_equal_p (XEXP (op0, 1), op1))
5426 && ! side_effects_p (XEXP (op0, 0))
5427 && ! side_effects_p (XEXP (op0, 1)))
5428 return op1;
5429
5430 /* If we have (ior (and A B) C), apply the distributive law and then
5431 the inverse distributive law to see if things simplify. */
5432
5433 if (GET_CODE (op0) == AND)
5434 {
5435 x = apply_distributive_law
5436 (gen_binary (AND, mode,
5437 gen_binary (IOR, mode, XEXP (op0, 0), op1),
5438 gen_binary (IOR, mode, XEXP (op0, 1),
5439 copy_rtx (op1))));
5440
5441 if (GET_CODE (x) != IOR)
5442 return x;
5443 }
5444
5445 if (GET_CODE (op1) == AND)
5446 {
5447 x = apply_distributive_law
5448 (gen_binary (AND, mode,
5449 gen_binary (IOR, mode, XEXP (op1, 0), op0),
5450 gen_binary (IOR, mode, XEXP (op1, 1),
5451 copy_rtx (op0))));
5452
5453 if (GET_CODE (x) != IOR)
5454 return x;
5455 }
5456
5457 /* Convert (ior (ashift A CX) (lshiftrt A CY)) where CX+CY equals the
5458 mode size to (rotate A CX). */
5459
5460 if (((GET_CODE (op0) == ASHIFT && GET_CODE (op1) == LSHIFTRT)
5461 || (GET_CODE (op1) == ASHIFT && GET_CODE (op0) == LSHIFTRT))
5462 && rtx_equal_p (XEXP (op0, 0), XEXP (op1, 0))
5463 && GET_CODE (XEXP (op0, 1)) == CONST_INT
5464 && GET_CODE (XEXP (op1, 1)) == CONST_INT
5465 && (INTVAL (XEXP (op0, 1)) + INTVAL (XEXP (op1, 1))
5466 == GET_MODE_BITSIZE (mode)))
5467 return gen_rtx_ROTATE (mode, XEXP (op0, 0),
5468 (GET_CODE (op0) == ASHIFT
5469 ? XEXP (op0, 1) : XEXP (op1, 1)));
5470
5471 /* If OP0 is (ashiftrt (plus ...) C), it might actually be
5472 a (sign_extend (plus ...)). If so, OP1 is a CONST_INT, and the PLUS
5473 does not affect any of the bits in OP1, it can really be done
5474 as a PLUS and we can associate. We do this by seeing if OP1
5475 can be safely shifted left C bits. */
5476 if (GET_CODE (op1) == CONST_INT && GET_CODE (op0) == ASHIFTRT
5477 && GET_CODE (XEXP (op0, 0)) == PLUS
5478 && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT
5479 && GET_CODE (XEXP (op0, 1)) == CONST_INT
5480 && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT)
5481 {
5482 int count = INTVAL (XEXP (op0, 1));
5483 HOST_WIDE_INT mask = INTVAL (op1) << count;
5484
5485 if (mask >> count == INTVAL (op1)
5486 && (mask & nonzero_bits (XEXP (op0, 0), mode)) == 0)
5487 {
5488 SUBST (XEXP (XEXP (op0, 0), 1),
5489 GEN_INT (INTVAL (XEXP (XEXP (op0, 0), 1)) | mask));
5490 return op0;
5491 }
5492 }
5493 break;
5494
5495 case XOR:
5496 /* If we are XORing two things that have no bits in common,
5497 convert them into an IOR. This helps to detect rotation encoded
5498 using those methods and possibly other simplifications. */
5499
5500 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
5501 && (nonzero_bits (op0, mode)
5502 & nonzero_bits (op1, mode)) == 0)
5503 return (gen_binary (IOR, mode, op0, op1));
5504
5505 /* Convert (XOR (NOT x) (NOT y)) to (XOR x y).
5506 Also convert (XOR (NOT x) y) to (NOT (XOR x y)), similarly for
5507 (NOT y). */
5508 {
5509 int num_negated = 0;
5510
5511 if (GET_CODE (op0) == NOT)
5512 num_negated++, op0 = XEXP (op0, 0);
5513 if (GET_CODE (op1) == NOT)
5514 num_negated++, op1 = XEXP (op1, 0);
5515
5516 if (num_negated == 2)
5517 {
5518 SUBST (XEXP (x, 0), op0);
5519 SUBST (XEXP (x, 1), op1);
5520 }
5521 else if (num_negated == 1)
5522 return
5523 simplify_gen_unary (NOT, mode, gen_binary (XOR, mode, op0, op1),
5524 mode);
5525 }
5526
5527 /* Convert (xor (and A B) B) to (and (not A) B). The latter may
5528 correspond to a machine insn or result in further simplifications
5529 if B is a constant. */
5530
5531 if (GET_CODE (op0) == AND
5532 && rtx_equal_p (XEXP (op0, 1), op1)
5533 && ! side_effects_p (op1))
5534 return gen_binary (AND, mode,
5535 simplify_gen_unary (NOT, mode, XEXP (op0, 0), mode),
5536 op1);
5537
5538 else if (GET_CODE (op0) == AND
5539 && rtx_equal_p (XEXP (op0, 0), op1)
5540 && ! side_effects_p (op1))
5541 return gen_binary (AND, mode,
5542 simplify_gen_unary (NOT, mode, XEXP (op0, 1), mode),
5543 op1);
5544
5545 /* (xor (comparison foo bar) (const_int 1)) can become the reversed
5546 comparison if STORE_FLAG_VALUE is 1. */
5547 if (STORE_FLAG_VALUE == 1
5548 && op1 == const1_rtx
5549 && GET_RTX_CLASS (GET_CODE (op0)) == '<'
5550 && (reversed = reversed_comparison (op0, mode, XEXP (op0, 0),
5551 XEXP (op0, 1))))
5552 return reversed;
5553
5554 /* (lshiftrt foo C) where C is the number of bits in FOO minus 1
5555 is (lt foo (const_int 0)), so we can perform the above
5556 simplification if STORE_FLAG_VALUE is 1. */
5557
5558 if (STORE_FLAG_VALUE == 1
5559 && op1 == const1_rtx
5560 && GET_CODE (op0) == LSHIFTRT
5561 && GET_CODE (XEXP (op0, 1)) == CONST_INT
5562 && INTVAL (XEXP (op0, 1)) == GET_MODE_BITSIZE (mode) - 1)
5563 return gen_rtx_GE (mode, XEXP (op0, 0), const0_rtx);
5564
5565 /* (xor (comparison foo bar) (const_int sign-bit))
5566 when STORE_FLAG_VALUE is the sign bit. */
5567 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
5568 && ((STORE_FLAG_VALUE & GET_MODE_MASK (mode))
5569 == (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1))
5570 && op1 == const_true_rtx
5571 && GET_RTX_CLASS (GET_CODE (op0)) == '<'
5572 && (reversed = reversed_comparison (op0, mode, XEXP (op0, 0),
5573 XEXP (op0, 1))))
5574 return reversed;
5575
5576 break;
5577
5578 default:
5579 abort ();
5580 }
5581
5582 return x;
5583 }
5584
5585 /* We consider ZERO_EXTRACT, SIGN_EXTRACT, and SIGN_EXTEND as "compound
5586 operations" because they can be replaced with two more basic operations.
5587 ZERO_EXTEND is also considered "compound" because it can be replaced with
5588 an AND operation, which is simpler, though only one operation.
5589
5590 The function expand_compound_operation is called with an rtx expression
5591 and will convert it to the appropriate shifts and AND operations,
5592 simplifying at each stage.
5593
5594 The function make_compound_operation is called to convert an expression
5595 consisting of shifts and ANDs into the equivalent compound expression.
5596 It is the inverse of this function, loosely speaking. */
5597
5598 static rtx
expand_compound_operation(rtx x)5599 expand_compound_operation (rtx x)
5600 {
5601 unsigned HOST_WIDE_INT pos = 0, len;
5602 int unsignedp = 0;
5603 unsigned int modewidth;
5604 rtx tem;
5605
5606 switch (GET_CODE (x))
5607 {
5608 case ZERO_EXTEND:
5609 unsignedp = 1;
5610 case SIGN_EXTEND:
5611 /* We can't necessarily use a const_int for a multiword mode;
5612 it depends on implicitly extending the value.
5613 Since we don't know the right way to extend it,
5614 we can't tell whether the implicit way is right.
5615
5616 Even for a mode that is no wider than a const_int,
5617 we can't win, because we need to sign extend one of its bits through
5618 the rest of it, and we don't know which bit. */
5619 if (GET_CODE (XEXP (x, 0)) == CONST_INT)
5620 return x;
5621
5622 /* Return if (subreg:MODE FROM 0) is not a safe replacement for
5623 (zero_extend:MODE FROM) or (sign_extend:MODE FROM). It is for any MEM
5624 because (SUBREG (MEM...)) is guaranteed to cause the MEM to be
5625 reloaded. If not for that, MEM's would very rarely be safe.
5626
5627 Reject MODEs bigger than a word, because we might not be able
5628 to reference a two-register group starting with an arbitrary register
5629 (and currently gen_lowpart might crash for a SUBREG). */
5630
5631 if (GET_MODE_SIZE (GET_MODE (XEXP (x, 0))) > UNITS_PER_WORD)
5632 return x;
5633
5634 /* Reject MODEs that aren't scalar integers because turning vector
5635 or complex modes into shifts causes problems. */
5636
5637 if (! SCALAR_INT_MODE_P (GET_MODE (XEXP (x, 0))))
5638 return x;
5639
5640 len = GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)));
5641 /* If the inner object has VOIDmode (the only way this can happen
5642 is if it is an ASM_OPERANDS), we can't do anything since we don't
5643 know how much masking to do. */
5644 if (len == 0)
5645 return x;
5646
5647 break;
5648
5649 case ZERO_EXTRACT:
5650 unsignedp = 1;
5651 case SIGN_EXTRACT:
5652 /* If the operand is a CLOBBER, just return it. */
5653 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
5654 return XEXP (x, 0);
5655
5656 if (GET_CODE (XEXP (x, 1)) != CONST_INT
5657 || GET_CODE (XEXP (x, 2)) != CONST_INT
5658 || GET_MODE (XEXP (x, 0)) == VOIDmode)
5659 return x;
5660
5661 /* Reject MODEs that aren't scalar integers because turning vector
5662 or complex modes into shifts causes problems. */
5663
5664 if (! SCALAR_INT_MODE_P (GET_MODE (XEXP (x, 0))))
5665 return x;
5666
5667 len = INTVAL (XEXP (x, 1));
5668 pos = INTVAL (XEXP (x, 2));
5669
5670 /* If this goes outside the object being extracted, replace the object
5671 with a (use (mem ...)) construct that only combine understands
5672 and is used only for this purpose. */
5673 if (len + pos > GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))))
5674 SUBST (XEXP (x, 0), gen_rtx_USE (GET_MODE (x), XEXP (x, 0)));
5675
5676 if (BITS_BIG_ENDIAN)
5677 pos = GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - len - pos;
5678
5679 break;
5680
5681 default:
5682 return x;
5683 }
5684 /* Convert sign extension to zero extension, if we know that the high
5685 bit is not set, as this is easier to optimize. It will be converted
5686 back to cheaper alternative in make_extraction. */
5687 if (GET_CODE (x) == SIGN_EXTEND
5688 && (GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT
5689 && ((nonzero_bits (XEXP (x, 0), GET_MODE (XEXP (x, 0)))
5690 & ~(((unsigned HOST_WIDE_INT)
5691 GET_MODE_MASK (GET_MODE (XEXP (x, 0))))
5692 >> 1))
5693 == 0)))
5694 {
5695 rtx temp = gen_rtx_ZERO_EXTEND (GET_MODE (x), XEXP (x, 0));
5696 rtx temp2 = expand_compound_operation (temp);
5697
5698 /* Make sure this is a profitable operation. */
5699 if (rtx_cost (x, SET) > rtx_cost (temp2, SET))
5700 return temp2;
5701 else if (rtx_cost (x, SET) > rtx_cost (temp, SET))
5702 return temp;
5703 else
5704 return x;
5705 }
5706
5707 /* We can optimize some special cases of ZERO_EXTEND. */
5708 if (GET_CODE (x) == ZERO_EXTEND)
5709 {
5710 /* (zero_extend:DI (truncate:SI foo:DI)) is just foo:DI if we
5711 know that the last value didn't have any inappropriate bits
5712 set. */
5713 if (GET_CODE (XEXP (x, 0)) == TRUNCATE
5714 && GET_MODE (XEXP (XEXP (x, 0), 0)) == GET_MODE (x)
5715 && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT
5716 && (nonzero_bits (XEXP (XEXP (x, 0), 0), GET_MODE (x))
5717 & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0)
5718 return XEXP (XEXP (x, 0), 0);
5719
5720 /* Likewise for (zero_extend:DI (subreg:SI foo:DI 0)). */
5721 if (GET_CODE (XEXP (x, 0)) == SUBREG
5722 && GET_MODE (SUBREG_REG (XEXP (x, 0))) == GET_MODE (x)
5723 && subreg_lowpart_p (XEXP (x, 0))
5724 && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT
5725 && (nonzero_bits (SUBREG_REG (XEXP (x, 0)), GET_MODE (x))
5726 & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0)
5727 return SUBREG_REG (XEXP (x, 0));
5728
5729 /* (zero_extend:DI (truncate:SI foo:DI)) is just foo:DI when foo
5730 is a comparison and STORE_FLAG_VALUE permits. This is like
5731 the first case, but it works even when GET_MODE (x) is larger
5732 than HOST_WIDE_INT. */
5733 if (GET_CODE (XEXP (x, 0)) == TRUNCATE
5734 && GET_MODE (XEXP (XEXP (x, 0), 0)) == GET_MODE (x)
5735 && GET_RTX_CLASS (GET_CODE (XEXP (XEXP (x, 0), 0))) == '<'
5736 && (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
5737 <= HOST_BITS_PER_WIDE_INT)
5738 && ((HOST_WIDE_INT) STORE_FLAG_VALUE
5739 & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0)
5740 return XEXP (XEXP (x, 0), 0);
5741
5742 /* Likewise for (zero_extend:DI (subreg:SI foo:DI 0)). */
5743 if (GET_CODE (XEXP (x, 0)) == SUBREG
5744 && GET_MODE (SUBREG_REG (XEXP (x, 0))) == GET_MODE (x)
5745 && subreg_lowpart_p (XEXP (x, 0))
5746 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0)))) == '<'
5747 && (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
5748 <= HOST_BITS_PER_WIDE_INT)
5749 && ((HOST_WIDE_INT) STORE_FLAG_VALUE
5750 & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0)
5751 return SUBREG_REG (XEXP (x, 0));
5752
5753 }
5754
5755 /* If we reach here, we want to return a pair of shifts. The inner
5756 shift is a left shift of BITSIZE - POS - LEN bits. The outer
5757 shift is a right shift of BITSIZE - LEN bits. It is arithmetic or
5758 logical depending on the value of UNSIGNEDP.
5759
5760 If this was a ZERO_EXTEND or ZERO_EXTRACT, this pair of shifts will be
5761 converted into an AND of a shift.
5762
5763 We must check for the case where the left shift would have a negative
5764 count. This can happen in a case like (x >> 31) & 255 on machines
5765 that can't shift by a constant. On those machines, we would first
5766 combine the shift with the AND to produce a variable-position
5767 extraction. Then the constant of 31 would be substituted in to produce
5768 a such a position. */
5769
5770 modewidth = GET_MODE_BITSIZE (GET_MODE (x));
5771 if (modewidth + len >= pos)
5772 tem = simplify_shift_const (NULL_RTX, unsignedp ? LSHIFTRT : ASHIFTRT,
5773 GET_MODE (x),
5774 simplify_shift_const (NULL_RTX, ASHIFT,
5775 GET_MODE (x),
5776 XEXP (x, 0),
5777 modewidth - pos - len),
5778 modewidth - len);
5779
5780 else if (unsignedp && len < HOST_BITS_PER_WIDE_INT)
5781 tem = simplify_and_const_int (NULL_RTX, GET_MODE (x),
5782 simplify_shift_const (NULL_RTX, LSHIFTRT,
5783 GET_MODE (x),
5784 XEXP (x, 0), pos),
5785 ((HOST_WIDE_INT) 1 << len) - 1);
5786 else
5787 /* Any other cases we can't handle. */
5788 return x;
5789
5790 /* If we couldn't do this for some reason, return the original
5791 expression. */
5792 if (GET_CODE (tem) == CLOBBER)
5793 return x;
5794
5795 return tem;
5796 }
5797
5798 /* X is a SET which contains an assignment of one object into
5799 a part of another (such as a bit-field assignment, STRICT_LOW_PART,
5800 or certain SUBREGS). If possible, convert it into a series of
5801 logical operations.
5802
5803 We half-heartedly support variable positions, but do not at all
5804 support variable lengths. */
5805
5806 static rtx
expand_field_assignment(rtx x)5807 expand_field_assignment (rtx x)
5808 {
5809 rtx inner;
5810 rtx pos; /* Always counts from low bit. */
5811 int len;
5812 rtx mask;
5813 enum machine_mode compute_mode;
5814
5815 /* Loop until we find something we can't simplify. */
5816 while (1)
5817 {
5818 if (GET_CODE (SET_DEST (x)) == STRICT_LOW_PART
5819 && GET_CODE (XEXP (SET_DEST (x), 0)) == SUBREG)
5820 {
5821 inner = SUBREG_REG (XEXP (SET_DEST (x), 0));
5822 len = GET_MODE_BITSIZE (GET_MODE (XEXP (SET_DEST (x), 0)));
5823 pos = GEN_INT (subreg_lsb (XEXP (SET_DEST (x), 0)));
5824 }
5825 else if (GET_CODE (SET_DEST (x)) == ZERO_EXTRACT
5826 && GET_CODE (XEXP (SET_DEST (x), 1)) == CONST_INT)
5827 {
5828 inner = XEXP (SET_DEST (x), 0);
5829 len = INTVAL (XEXP (SET_DEST (x), 1));
5830 pos = XEXP (SET_DEST (x), 2);
5831
5832 /* If the position is constant and spans the width of INNER,
5833 surround INNER with a USE to indicate this. */
5834 if (GET_CODE (pos) == CONST_INT
5835 && INTVAL (pos) + len > GET_MODE_BITSIZE (GET_MODE (inner)))
5836 inner = gen_rtx_USE (GET_MODE (SET_DEST (x)), inner);
5837
5838 if (BITS_BIG_ENDIAN)
5839 {
5840 if (GET_CODE (pos) == CONST_INT)
5841 pos = GEN_INT (GET_MODE_BITSIZE (GET_MODE (inner)) - len
5842 - INTVAL (pos));
5843 else if (GET_CODE (pos) == MINUS
5844 && GET_CODE (XEXP (pos, 1)) == CONST_INT
5845 && (INTVAL (XEXP (pos, 1))
5846 == GET_MODE_BITSIZE (GET_MODE (inner)) - len))
5847 /* If position is ADJUST - X, new position is X. */
5848 pos = XEXP (pos, 0);
5849 else
5850 pos = gen_binary (MINUS, GET_MODE (pos),
5851 GEN_INT (GET_MODE_BITSIZE (GET_MODE (inner))
5852 - len),
5853 pos);
5854 }
5855 }
5856
5857 /* A SUBREG between two modes that occupy the same numbers of words
5858 can be done by moving the SUBREG to the source. */
5859 else if (GET_CODE (SET_DEST (x)) == SUBREG
5860 /* We need SUBREGs to compute nonzero_bits properly. */
5861 && nonzero_sign_valid
5862 && (((GET_MODE_SIZE (GET_MODE (SET_DEST (x)))
5863 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
5864 == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x))))
5865 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)))
5866 {
5867 x = gen_rtx_SET (VOIDmode, SUBREG_REG (SET_DEST (x)),
5868 gen_lowpart_for_combine
5869 (GET_MODE (SUBREG_REG (SET_DEST (x))),
5870 SET_SRC (x)));
5871 continue;
5872 }
5873 else
5874 break;
5875
5876 while (GET_CODE (inner) == SUBREG && subreg_lowpart_p (inner))
5877 inner = SUBREG_REG (inner);
5878
5879 compute_mode = GET_MODE (inner);
5880
5881 /* Don't attempt bitwise arithmetic on non scalar integer modes. */
5882 if (! SCALAR_INT_MODE_P (compute_mode))
5883 {
5884 enum machine_mode imode;
5885
5886 /* Don't do anything for vector or complex integral types. */
5887 if (! FLOAT_MODE_P (compute_mode))
5888 break;
5889
5890 /* Try to find an integral mode to pun with. */
5891 imode = mode_for_size (GET_MODE_BITSIZE (compute_mode), MODE_INT, 0);
5892 if (imode == BLKmode)
5893 break;
5894
5895 compute_mode = imode;
5896 inner = gen_lowpart_for_combine (imode, inner);
5897 }
5898
5899 /* Compute a mask of LEN bits, if we can do this on the host machine. */
5900 if (len < HOST_BITS_PER_WIDE_INT)
5901 mask = GEN_INT (((HOST_WIDE_INT) 1 << len) - 1);
5902 else
5903 break;
5904
5905 /* Now compute the equivalent expression. Make a copy of INNER
5906 for the SET_DEST in case it is a MEM into which we will substitute;
5907 we don't want shared RTL in that case. */
5908 x = gen_rtx_SET
5909 (VOIDmode, copy_rtx (inner),
5910 gen_binary (IOR, compute_mode,
5911 gen_binary (AND, compute_mode,
5912 simplify_gen_unary (NOT, compute_mode,
5913 gen_binary (ASHIFT,
5914 compute_mode,
5915 mask, pos),
5916 compute_mode),
5917 inner),
5918 gen_binary (ASHIFT, compute_mode,
5919 gen_binary (AND, compute_mode,
5920 gen_lowpart_for_combine
5921 (compute_mode, SET_SRC (x)),
5922 mask),
5923 pos)));
5924 }
5925
5926 return x;
5927 }
5928
5929 /* Return an RTX for a reference to LEN bits of INNER. If POS_RTX is nonzero,
5930 it is an RTX that represents a variable starting position; otherwise,
5931 POS is the (constant) starting bit position (counted from the LSB).
5932
5933 INNER may be a USE. This will occur when we started with a bitfield
5934 that went outside the boundary of the object in memory, which is
5935 allowed on most machines. To isolate this case, we produce a USE
5936 whose mode is wide enough and surround the MEM with it. The only
5937 code that understands the USE is this routine. If it is not removed,
5938 it will cause the resulting insn not to match.
5939
5940 UNSIGNEDP is nonzero for an unsigned reference and zero for a
5941 signed reference.
5942
5943 IN_DEST is nonzero if this is a reference in the destination of a
5944 SET. This is used when a ZERO_ or SIGN_EXTRACT isn't needed. If nonzero,
5945 a STRICT_LOW_PART will be used, if zero, ZERO_EXTEND or SIGN_EXTEND will
5946 be used.
5947
5948 IN_COMPARE is nonzero if we are in a COMPARE. This means that a
5949 ZERO_EXTRACT should be built even for bits starting at bit 0.
5950
5951 MODE is the desired mode of the result (if IN_DEST == 0).
5952
5953 The result is an RTX for the extraction or NULL_RTX if the target
5954 can't handle it. */
5955
5956 static rtx
make_extraction(enum machine_mode mode,rtx inner,HOST_WIDE_INT pos,rtx pos_rtx,unsigned HOST_WIDE_INT len,int unsignedp,int in_dest,int in_compare)5957 make_extraction (enum machine_mode mode, rtx inner, HOST_WIDE_INT pos,
5958 rtx pos_rtx, unsigned HOST_WIDE_INT len, int unsignedp,
5959 int in_dest, int in_compare)
5960 {
5961 /* This mode describes the size of the storage area
5962 to fetch the overall value from. Within that, we
5963 ignore the POS lowest bits, etc. */
5964 enum machine_mode is_mode = GET_MODE (inner);
5965 enum machine_mode inner_mode;
5966 enum machine_mode wanted_inner_mode = byte_mode;
5967 enum machine_mode wanted_inner_reg_mode = word_mode;
5968 enum machine_mode pos_mode = word_mode;
5969 enum machine_mode extraction_mode = word_mode;
5970 enum machine_mode tmode = mode_for_size (len, MODE_INT, 1);
5971 int spans_byte = 0;
5972 rtx new = 0;
5973 rtx orig_pos_rtx = pos_rtx;
5974 HOST_WIDE_INT orig_pos;
5975
5976 /* Get some information about INNER and get the innermost object. */
5977 if (GET_CODE (inner) == USE)
5978 /* (use:SI (mem:QI foo)) stands for (mem:SI foo). */
5979 /* We don't need to adjust the position because we set up the USE
5980 to pretend that it was a full-word object. */
5981 spans_byte = 1, inner = XEXP (inner, 0);
5982 else if (GET_CODE (inner) == SUBREG && subreg_lowpart_p (inner))
5983 {
5984 /* If going from (subreg:SI (mem:QI ...)) to (mem:QI ...),
5985 consider just the QI as the memory to extract from.
5986 The subreg adds or removes high bits; its mode is
5987 irrelevant to the meaning of this extraction,
5988 since POS and LEN count from the lsb. */
5989 if (GET_CODE (SUBREG_REG (inner)) == MEM)
5990 is_mode = GET_MODE (SUBREG_REG (inner));
5991 inner = SUBREG_REG (inner);
5992 }
5993 else if (GET_CODE (inner) == ASHIFT
5994 && GET_CODE (XEXP (inner, 1)) == CONST_INT
5995 && pos_rtx == 0 && pos == 0
5996 && len > (unsigned HOST_WIDE_INT) INTVAL (XEXP (inner, 1)))
5997 {
5998 /* We're extracting the least significant bits of an rtx
5999 (ashift X (const_int C)), where LEN > C. Extract the
6000 least significant (LEN - C) bits of X, giving an rtx
6001 whose mode is MODE, then shift it left C times. */
6002 new = make_extraction (mode, XEXP (inner, 0),
6003 0, 0, len - INTVAL (XEXP (inner, 1)),
6004 unsignedp, in_dest, in_compare);
6005 if (new != 0)
6006 return gen_rtx_ASHIFT (mode, new, XEXP (inner, 1));
6007 }
6008
6009 inner_mode = GET_MODE (inner);
6010
6011 if (pos_rtx && GET_CODE (pos_rtx) == CONST_INT)
6012 pos = INTVAL (pos_rtx), pos_rtx = 0;
6013
6014 /* See if this can be done without an extraction. We never can if the
6015 width of the field is not the same as that of some integer mode. For
6016 registers, we can only avoid the extraction if the position is at the
6017 low-order bit and this is either not in the destination or we have the
6018 appropriate STRICT_LOW_PART operation available.
6019
6020 For MEM, we can avoid an extract if the field starts on an appropriate
6021 boundary and we can change the mode of the memory reference. However,
6022 we cannot directly access the MEM if we have a USE and the underlying
6023 MEM is not TMODE. This combination means that MEM was being used in a
6024 context where bits outside its mode were being referenced; that is only
6025 valid in bit-field insns. */
6026
6027 if (tmode != BLKmode
6028 && ! (spans_byte && inner_mode != tmode)
6029 && ((pos_rtx == 0 && (pos % BITS_PER_WORD) == 0
6030 && GET_CODE (inner) != MEM
6031 && (! in_dest
6032 || (GET_CODE (inner) == REG
6033 && have_insn_for (STRICT_LOW_PART, tmode))))
6034 || (GET_CODE (inner) == MEM && pos_rtx == 0
6035 && (pos
6036 % (STRICT_ALIGNMENT ? GET_MODE_ALIGNMENT (tmode)
6037 : BITS_PER_UNIT)) == 0
6038 /* We can't do this if we are widening INNER_MODE (it
6039 may not be aligned, for one thing). */
6040 && GET_MODE_BITSIZE (inner_mode) >= GET_MODE_BITSIZE (tmode)
6041 && (inner_mode == tmode
6042 || (! mode_dependent_address_p (XEXP (inner, 0))
6043 && ! MEM_VOLATILE_P (inner))))))
6044 {
6045 /* If INNER is a MEM, make a new MEM that encompasses just the desired
6046 field. If the original and current mode are the same, we need not
6047 adjust the offset. Otherwise, we do if bytes big endian.
6048
6049 If INNER is not a MEM, get a piece consisting of just the field
6050 of interest (in this case POS % BITS_PER_WORD must be 0). */
6051
6052 if (GET_CODE (inner) == MEM)
6053 {
6054 HOST_WIDE_INT offset;
6055
6056 /* POS counts from lsb, but make OFFSET count in memory order. */
6057 if (BYTES_BIG_ENDIAN)
6058 offset = (GET_MODE_BITSIZE (is_mode) - len - pos) / BITS_PER_UNIT;
6059 else
6060 offset = pos / BITS_PER_UNIT;
6061
6062 new = adjust_address_nv (inner, tmode, offset);
6063 }
6064 else if (GET_CODE (inner) == REG)
6065 {
6066 if (tmode != inner_mode)
6067 {
6068 /* We can't call gen_lowpart_for_combine in a DEST since we
6069 always want a SUBREG (see below) and it would sometimes
6070 return a new hard register. */
6071 if (pos || in_dest)
6072 {
6073 HOST_WIDE_INT final_word = pos / BITS_PER_WORD;
6074
6075 if (WORDS_BIG_ENDIAN
6076 && GET_MODE_SIZE (inner_mode) > UNITS_PER_WORD)
6077 final_word = ((GET_MODE_SIZE (inner_mode)
6078 - GET_MODE_SIZE (tmode))
6079 / UNITS_PER_WORD) - final_word;
6080
6081 final_word *= UNITS_PER_WORD;
6082 if (BYTES_BIG_ENDIAN &&
6083 GET_MODE_SIZE (inner_mode) > GET_MODE_SIZE (tmode))
6084 final_word += (GET_MODE_SIZE (inner_mode)
6085 - GET_MODE_SIZE (tmode)) % UNITS_PER_WORD;
6086
6087 /* Avoid creating invalid subregs, for example when
6088 simplifying (x>>32)&255. */
6089 if (final_word >= GET_MODE_SIZE (inner_mode))
6090 return NULL_RTX;
6091
6092 new = gen_rtx_SUBREG (tmode, inner, final_word);
6093 }
6094 else
6095 new = gen_lowpart_for_combine (tmode, inner);
6096 }
6097 else
6098 new = inner;
6099 }
6100 else
6101 new = force_to_mode (inner, tmode,
6102 len >= HOST_BITS_PER_WIDE_INT
6103 ? ~(unsigned HOST_WIDE_INT) 0
6104 : ((unsigned HOST_WIDE_INT) 1 << len) - 1,
6105 NULL_RTX, 0);
6106
6107 /* If this extraction is going into the destination of a SET,
6108 make a STRICT_LOW_PART unless we made a MEM. */
6109
6110 if (in_dest)
6111 return (GET_CODE (new) == MEM ? new
6112 : (GET_CODE (new) != SUBREG
6113 ? gen_rtx_CLOBBER (tmode, const0_rtx)
6114 : gen_rtx_STRICT_LOW_PART (VOIDmode, new)));
6115
6116 if (mode == tmode)
6117 return new;
6118
6119 if (GET_CODE (new) == CONST_INT)
6120 return gen_int_mode (INTVAL (new), mode);
6121
6122 /* If we know that no extraneous bits are set, and that the high
6123 bit is not set, convert the extraction to the cheaper of
6124 sign and zero extension, that are equivalent in these cases. */
6125 if (flag_expensive_optimizations
6126 && (GET_MODE_BITSIZE (tmode) <= HOST_BITS_PER_WIDE_INT
6127 && ((nonzero_bits (new, tmode)
6128 & ~(((unsigned HOST_WIDE_INT)
6129 GET_MODE_MASK (tmode))
6130 >> 1))
6131 == 0)))
6132 {
6133 rtx temp = gen_rtx_ZERO_EXTEND (mode, new);
6134 rtx temp1 = gen_rtx_SIGN_EXTEND (mode, new);
6135
6136 /* Prefer ZERO_EXTENSION, since it gives more information to
6137 backends. */
6138 if (rtx_cost (temp, SET) <= rtx_cost (temp1, SET))
6139 return temp;
6140 return temp1;
6141 }
6142
6143 /* Otherwise, sign- or zero-extend unless we already are in the
6144 proper mode. */
6145
6146 return (gen_rtx_fmt_e (unsignedp ? ZERO_EXTEND : SIGN_EXTEND,
6147 mode, new));
6148 }
6149
6150 /* Unless this is a COMPARE or we have a funny memory reference,
6151 don't do anything with zero-extending field extracts starting at
6152 the low-order bit since they are simple AND operations. */
6153 if (pos_rtx == 0 && pos == 0 && ! in_dest
6154 && ! in_compare && ! spans_byte && unsignedp)
6155 return 0;
6156
6157 /* Unless we are allowed to span bytes or INNER is not MEM, reject this if
6158 we would be spanning bytes or if the position is not a constant and the
6159 length is not 1. In all other cases, we would only be going outside
6160 our object in cases when an original shift would have been
6161 undefined. */
6162 if (! spans_byte && GET_CODE (inner) == MEM
6163 && ((pos_rtx == 0 && pos + len > GET_MODE_BITSIZE (is_mode))
6164 || (pos_rtx != 0 && len != 1)))
6165 return 0;
6166
6167 /* Get the mode to use should INNER not be a MEM, the mode for the position,
6168 and the mode for the result. */
6169 if (in_dest && mode_for_extraction (EP_insv, -1) != MAX_MACHINE_MODE)
6170 {
6171 wanted_inner_reg_mode = mode_for_extraction (EP_insv, 0);
6172 pos_mode = mode_for_extraction (EP_insv, 2);
6173 extraction_mode = mode_for_extraction (EP_insv, 3);
6174 }
6175
6176 if (! in_dest && unsignedp
6177 && mode_for_extraction (EP_extzv, -1) != MAX_MACHINE_MODE)
6178 {
6179 wanted_inner_reg_mode = mode_for_extraction (EP_extzv, 1);
6180 pos_mode = mode_for_extraction (EP_extzv, 3);
6181 extraction_mode = mode_for_extraction (EP_extzv, 0);
6182 }
6183
6184 if (! in_dest && ! unsignedp
6185 && mode_for_extraction (EP_extv, -1) != MAX_MACHINE_MODE)
6186 {
6187 wanted_inner_reg_mode = mode_for_extraction (EP_extv, 1);
6188 pos_mode = mode_for_extraction (EP_extv, 3);
6189 extraction_mode = mode_for_extraction (EP_extv, 0);
6190 }
6191
6192 /* Never narrow an object, since that might not be safe. */
6193
6194 if (mode != VOIDmode
6195 && GET_MODE_SIZE (extraction_mode) < GET_MODE_SIZE (mode))
6196 extraction_mode = mode;
6197
6198 if (pos_rtx && GET_MODE (pos_rtx) != VOIDmode
6199 && GET_MODE_SIZE (pos_mode) < GET_MODE_SIZE (GET_MODE (pos_rtx)))
6200 pos_mode = GET_MODE (pos_rtx);
6201
6202 /* If this is not from memory, the desired mode is wanted_inner_reg_mode;
6203 if we have to change the mode of memory and cannot, the desired mode is
6204 EXTRACTION_MODE. */
6205 if (GET_CODE (inner) != MEM)
6206 wanted_inner_mode = wanted_inner_reg_mode;
6207 else if (inner_mode != wanted_inner_mode
6208 && (mode_dependent_address_p (XEXP (inner, 0))
6209 || MEM_VOLATILE_P (inner)))
6210 wanted_inner_mode = extraction_mode;
6211
6212 orig_pos = pos;
6213
6214 if (BITS_BIG_ENDIAN)
6215 {
6216 /* POS is passed as if BITS_BIG_ENDIAN == 0, so we need to convert it to
6217 BITS_BIG_ENDIAN style. If position is constant, compute new
6218 position. Otherwise, build subtraction.
6219 Note that POS is relative to the mode of the original argument.
6220 If it's a MEM we need to recompute POS relative to that.
6221 However, if we're extracting from (or inserting into) a register,
6222 we want to recompute POS relative to wanted_inner_mode. */
6223 int width = (GET_CODE (inner) == MEM
6224 ? GET_MODE_BITSIZE (is_mode)
6225 : GET_MODE_BITSIZE (wanted_inner_mode));
6226
6227 if (pos_rtx == 0)
6228 pos = width - len - pos;
6229 else
6230 pos_rtx
6231 = gen_rtx_MINUS (GET_MODE (pos_rtx), GEN_INT (width - len), pos_rtx);
6232 /* POS may be less than 0 now, but we check for that below.
6233 Note that it can only be less than 0 if GET_CODE (inner) != MEM. */
6234 }
6235
6236 /* If INNER has a wider mode, make it smaller. If this is a constant
6237 extract, try to adjust the byte to point to the byte containing
6238 the value. */
6239 if (wanted_inner_mode != VOIDmode
6240 && GET_MODE_SIZE (wanted_inner_mode) < GET_MODE_SIZE (is_mode)
6241 && ((GET_CODE (inner) == MEM
6242 && (inner_mode == wanted_inner_mode
6243 || (! mode_dependent_address_p (XEXP (inner, 0))
6244 && ! MEM_VOLATILE_P (inner))))))
6245 {
6246 int offset = 0;
6247
6248 /* The computations below will be correct if the machine is big
6249 endian in both bits and bytes or little endian in bits and bytes.
6250 If it is mixed, we must adjust. */
6251
6252 /* If bytes are big endian and we had a paradoxical SUBREG, we must
6253 adjust OFFSET to compensate. */
6254 if (BYTES_BIG_ENDIAN
6255 && ! spans_byte
6256 && GET_MODE_SIZE (inner_mode) < GET_MODE_SIZE (is_mode))
6257 offset -= GET_MODE_SIZE (is_mode) - GET_MODE_SIZE (inner_mode);
6258
6259 /* If this is a constant position, we can move to the desired byte. */
6260 if (pos_rtx == 0)
6261 {
6262 offset += pos / BITS_PER_UNIT;
6263 pos %= GET_MODE_BITSIZE (wanted_inner_mode);
6264 }
6265
6266 if (BYTES_BIG_ENDIAN != BITS_BIG_ENDIAN
6267 && ! spans_byte
6268 && is_mode != wanted_inner_mode)
6269 offset = (GET_MODE_SIZE (is_mode)
6270 - GET_MODE_SIZE (wanted_inner_mode) - offset);
6271
6272 if (offset != 0 || inner_mode != wanted_inner_mode)
6273 inner = adjust_address_nv (inner, wanted_inner_mode, offset);
6274 }
6275
6276 /* If INNER is not memory, we can always get it into the proper mode. If we
6277 are changing its mode, POS must be a constant and smaller than the size
6278 of the new mode. */
6279 else if (GET_CODE (inner) != MEM)
6280 {
6281 if (GET_MODE (inner) != wanted_inner_mode
6282 && (pos_rtx != 0
6283 || orig_pos + len > GET_MODE_BITSIZE (wanted_inner_mode)))
6284 return 0;
6285
6286 inner = force_to_mode (inner, wanted_inner_mode,
6287 pos_rtx
6288 || len + orig_pos >= HOST_BITS_PER_WIDE_INT
6289 ? ~(unsigned HOST_WIDE_INT) 0
6290 : ((((unsigned HOST_WIDE_INT) 1 << len) - 1)
6291 << orig_pos),
6292 NULL_RTX, 0);
6293 }
6294
6295 /* Adjust mode of POS_RTX, if needed. If we want a wider mode, we
6296 have to zero extend. Otherwise, we can just use a SUBREG. */
6297 if (pos_rtx != 0
6298 && GET_MODE_SIZE (pos_mode) > GET_MODE_SIZE (GET_MODE (pos_rtx)))
6299 {
6300 rtx temp = gen_rtx_ZERO_EXTEND (pos_mode, pos_rtx);
6301
6302 /* If we know that no extraneous bits are set, and that the high
6303 bit is not set, convert extraction to cheaper one - either
6304 SIGN_EXTENSION or ZERO_EXTENSION, that are equivalent in these
6305 cases. */
6306 if (flag_expensive_optimizations
6307 && (GET_MODE_BITSIZE (GET_MODE (pos_rtx)) <= HOST_BITS_PER_WIDE_INT
6308 && ((nonzero_bits (pos_rtx, GET_MODE (pos_rtx))
6309 & ~(((unsigned HOST_WIDE_INT)
6310 GET_MODE_MASK (GET_MODE (pos_rtx)))
6311 >> 1))
6312 == 0)))
6313 {
6314 rtx temp1 = gen_rtx_SIGN_EXTEND (pos_mode, pos_rtx);
6315
6316 /* Prefer ZERO_EXTENSION, since it gives more information to
6317 backends. */
6318 if (rtx_cost (temp1, SET) < rtx_cost (temp, SET))
6319 temp = temp1;
6320 }
6321 pos_rtx = temp;
6322 }
6323 else if (pos_rtx != 0
6324 && GET_MODE_SIZE (pos_mode) < GET_MODE_SIZE (GET_MODE (pos_rtx)))
6325 pos_rtx = gen_lowpart_for_combine (pos_mode, pos_rtx);
6326
6327 /* Make POS_RTX unless we already have it and it is correct. If we don't
6328 have a POS_RTX but we do have an ORIG_POS_RTX, the latter must
6329 be a CONST_INT. */
6330 if (pos_rtx == 0 && orig_pos_rtx != 0 && INTVAL (orig_pos_rtx) == pos)
6331 pos_rtx = orig_pos_rtx;
6332
6333 else if (pos_rtx == 0)
6334 pos_rtx = GEN_INT (pos);
6335
6336 /* Make the required operation. See if we can use existing rtx. */
6337 new = gen_rtx_fmt_eee (unsignedp ? ZERO_EXTRACT : SIGN_EXTRACT,
6338 extraction_mode, inner, GEN_INT (len), pos_rtx);
6339 if (! in_dest)
6340 new = gen_lowpart_for_combine (mode, new);
6341
6342 return new;
6343 }
6344
6345 /* See if X contains an ASHIFT of COUNT or more bits that can be commuted
6346 with any other operations in X. Return X without that shift if so. */
6347
6348 static rtx
extract_left_shift(rtx x,int count)6349 extract_left_shift (rtx x, int count)
6350 {
6351 enum rtx_code code = GET_CODE (x);
6352 enum machine_mode mode = GET_MODE (x);
6353 rtx tem;
6354
6355 switch (code)
6356 {
6357 case ASHIFT:
6358 /* This is the shift itself. If it is wide enough, we will return
6359 either the value being shifted if the shift count is equal to
6360 COUNT or a shift for the difference. */
6361 if (GET_CODE (XEXP (x, 1)) == CONST_INT
6362 && INTVAL (XEXP (x, 1)) >= count)
6363 return simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (x, 0),
6364 INTVAL (XEXP (x, 1)) - count);
6365 break;
6366
6367 case NEG: case NOT:
6368 if ((tem = extract_left_shift (XEXP (x, 0), count)) != 0)
6369 return simplify_gen_unary (code, mode, tem, mode);
6370
6371 break;
6372
6373 case PLUS: case IOR: case XOR: case AND:
6374 /* If we can safely shift this constant and we find the inner shift,
6375 make a new operation. */
6376 if (GET_CODE (XEXP (x, 1)) == CONST_INT
6377 && (INTVAL (XEXP (x, 1)) & ((((HOST_WIDE_INT) 1 << count)) - 1)) == 0
6378 && (tem = extract_left_shift (XEXP (x, 0), count)) != 0)
6379 return gen_binary (code, mode, tem,
6380 GEN_INT (INTVAL (XEXP (x, 1)) >> count));
6381
6382 break;
6383
6384 default:
6385 break;
6386 }
6387
6388 return 0;
6389 }
6390
6391 /* Look at the expression rooted at X. Look for expressions
6392 equivalent to ZERO_EXTRACT, SIGN_EXTRACT, ZERO_EXTEND, SIGN_EXTEND.
6393 Form these expressions.
6394
6395 Return the new rtx, usually just X.
6396
6397 Also, for machines like the VAX that don't have logical shift insns,
6398 try to convert logical to arithmetic shift operations in cases where
6399 they are equivalent. This undoes the canonicalizations to logical
6400 shifts done elsewhere.
6401
6402 We try, as much as possible, to re-use rtl expressions to save memory.
6403
6404 IN_CODE says what kind of expression we are processing. Normally, it is
6405 SET. In a memory address (inside a MEM, PLUS or minus, the latter two
6406 being kludges), it is MEM. When processing the arguments of a comparison
6407 or a COMPARE against zero, it is COMPARE. */
6408
6409 static rtx
make_compound_operation(rtx x,enum rtx_code in_code)6410 make_compound_operation (rtx x, enum rtx_code in_code)
6411 {
6412 enum rtx_code code = GET_CODE (x);
6413 enum machine_mode mode = GET_MODE (x);
6414 int mode_width = GET_MODE_BITSIZE (mode);
6415 rtx rhs, lhs;
6416 enum rtx_code next_code;
6417 int i;
6418 rtx new = 0;
6419 rtx tem;
6420 const char *fmt;
6421
6422 /* Select the code to be used in recursive calls. Once we are inside an
6423 address, we stay there. If we have a comparison, set to COMPARE,
6424 but once inside, go back to our default of SET. */
6425
6426 next_code = (code == MEM || code == PLUS || code == MINUS ? MEM
6427 : ((code == COMPARE || GET_RTX_CLASS (code) == '<')
6428 && XEXP (x, 1) == const0_rtx) ? COMPARE
6429 : in_code == COMPARE ? SET : in_code);
6430
6431 /* Process depending on the code of this operation. If NEW is set
6432 nonzero, it will be returned. */
6433
6434 switch (code)
6435 {
6436 case ASHIFT:
6437 /* Convert shifts by constants into multiplications if inside
6438 an address. */
6439 if (in_code == MEM && GET_CODE (XEXP (x, 1)) == CONST_INT
6440 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT
6441 && INTVAL (XEXP (x, 1)) >= 0)
6442 {
6443 new = make_compound_operation (XEXP (x, 0), next_code);
6444 new = gen_rtx_MULT (mode, new,
6445 GEN_INT ((HOST_WIDE_INT) 1
6446 << INTVAL (XEXP (x, 1))));
6447 }
6448 break;
6449
6450 case AND:
6451 /* If the second operand is not a constant, we can't do anything
6452 with it. */
6453 if (GET_CODE (XEXP (x, 1)) != CONST_INT)
6454 break;
6455
6456 /* If the constant is a power of two minus one and the first operand
6457 is a logical right shift, make an extraction. */
6458 if (GET_CODE (XEXP (x, 0)) == LSHIFTRT
6459 && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0)
6460 {
6461 new = make_compound_operation (XEXP (XEXP (x, 0), 0), next_code);
6462 new = make_extraction (mode, new, 0, XEXP (XEXP (x, 0), 1), i, 1,
6463 0, in_code == COMPARE);
6464 }
6465
6466 /* Same as previous, but for (subreg (lshiftrt ...)) in first op. */
6467 else if (GET_CODE (XEXP (x, 0)) == SUBREG
6468 && subreg_lowpart_p (XEXP (x, 0))
6469 && GET_CODE (SUBREG_REG (XEXP (x, 0))) == LSHIFTRT
6470 && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0)
6471 {
6472 new = make_compound_operation (XEXP (SUBREG_REG (XEXP (x, 0)), 0),
6473 next_code);
6474 new = make_extraction (GET_MODE (SUBREG_REG (XEXP (x, 0))), new, 0,
6475 XEXP (SUBREG_REG (XEXP (x, 0)), 1), i, 1,
6476 0, in_code == COMPARE);
6477 }
6478 /* Same as previous, but for (xor/ior (lshiftrt...) (lshiftrt...)). */
6479 else if ((GET_CODE (XEXP (x, 0)) == XOR
6480 || GET_CODE (XEXP (x, 0)) == IOR)
6481 && GET_CODE (XEXP (XEXP (x, 0), 0)) == LSHIFTRT
6482 && GET_CODE (XEXP (XEXP (x, 0), 1)) == LSHIFTRT
6483 && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0)
6484 {
6485 /* Apply the distributive law, and then try to make extractions. */
6486 new = gen_rtx_fmt_ee (GET_CODE (XEXP (x, 0)), mode,
6487 gen_rtx_AND (mode, XEXP (XEXP (x, 0), 0),
6488 XEXP (x, 1)),
6489 gen_rtx_AND (mode, XEXP (XEXP (x, 0), 1),
6490 XEXP (x, 1)));
6491 new = make_compound_operation (new, in_code);
6492 }
6493
6494 /* If we are have (and (rotate X C) M) and C is larger than the number
6495 of bits in M, this is an extraction. */
6496
6497 else if (GET_CODE (XEXP (x, 0)) == ROTATE
6498 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6499 && (i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0
6500 && i <= INTVAL (XEXP (XEXP (x, 0), 1)))
6501 {
6502 new = make_compound_operation (XEXP (XEXP (x, 0), 0), next_code);
6503 new = make_extraction (mode, new,
6504 (GET_MODE_BITSIZE (mode)
6505 - INTVAL (XEXP (XEXP (x, 0), 1))),
6506 NULL_RTX, i, 1, 0, in_code == COMPARE);
6507 }
6508
6509 /* On machines without logical shifts, if the operand of the AND is
6510 a logical shift and our mask turns off all the propagated sign
6511 bits, we can replace the logical shift with an arithmetic shift. */
6512 else if (GET_CODE (XEXP (x, 0)) == LSHIFTRT
6513 && !have_insn_for (LSHIFTRT, mode)
6514 && have_insn_for (ASHIFTRT, mode)
6515 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6516 && INTVAL (XEXP (XEXP (x, 0), 1)) >= 0
6517 && INTVAL (XEXP (XEXP (x, 0), 1)) < HOST_BITS_PER_WIDE_INT
6518 && mode_width <= HOST_BITS_PER_WIDE_INT)
6519 {
6520 unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode);
6521
6522 mask >>= INTVAL (XEXP (XEXP (x, 0), 1));
6523 if ((INTVAL (XEXP (x, 1)) & ~mask) == 0)
6524 SUBST (XEXP (x, 0),
6525 gen_rtx_ASHIFTRT (mode,
6526 make_compound_operation
6527 (XEXP (XEXP (x, 0), 0), next_code),
6528 XEXP (XEXP (x, 0), 1)));
6529 }
6530
6531 /* If the constant is one less than a power of two, this might be
6532 representable by an extraction even if no shift is present.
6533 If it doesn't end up being a ZERO_EXTEND, we will ignore it unless
6534 we are in a COMPARE. */
6535 else if ((i = exact_log2 (INTVAL (XEXP (x, 1)) + 1)) >= 0)
6536 new = make_extraction (mode,
6537 make_compound_operation (XEXP (x, 0),
6538 next_code),
6539 0, NULL_RTX, i, 1, 0, in_code == COMPARE);
6540
6541 /* If we are in a comparison and this is an AND with a power of two,
6542 convert this into the appropriate bit extract. */
6543 else if (in_code == COMPARE
6544 && (i = exact_log2 (INTVAL (XEXP (x, 1)))) >= 0)
6545 new = make_extraction (mode,
6546 make_compound_operation (XEXP (x, 0),
6547 next_code),
6548 i, NULL_RTX, 1, 1, 0, 1);
6549
6550 break;
6551
6552 case LSHIFTRT:
6553 /* If the sign bit is known to be zero, replace this with an
6554 arithmetic shift. */
6555 if (have_insn_for (ASHIFTRT, mode)
6556 && ! have_insn_for (LSHIFTRT, mode)
6557 && mode_width <= HOST_BITS_PER_WIDE_INT
6558 && (nonzero_bits (XEXP (x, 0), mode) & (1 << (mode_width - 1))) == 0)
6559 {
6560 new = gen_rtx_ASHIFTRT (mode,
6561 make_compound_operation (XEXP (x, 0),
6562 next_code),
6563 XEXP (x, 1));
6564 break;
6565 }
6566
6567 /* ... fall through ... */
6568
6569 case ASHIFTRT:
6570 lhs = XEXP (x, 0);
6571 rhs = XEXP (x, 1);
6572
6573 /* If we have (ashiftrt (ashift foo C1) C2) with C2 >= C1,
6574 this is a SIGN_EXTRACT. */
6575 if (GET_CODE (rhs) == CONST_INT
6576 && GET_CODE (lhs) == ASHIFT
6577 && GET_CODE (XEXP (lhs, 1)) == CONST_INT
6578 && INTVAL (rhs) >= INTVAL (XEXP (lhs, 1)))
6579 {
6580 new = make_compound_operation (XEXP (lhs, 0), next_code);
6581 new = make_extraction (mode, new,
6582 INTVAL (rhs) - INTVAL (XEXP (lhs, 1)),
6583 NULL_RTX, mode_width - INTVAL (rhs),
6584 code == LSHIFTRT, 0, in_code == COMPARE);
6585 break;
6586 }
6587
6588 /* See if we have operations between an ASHIFTRT and an ASHIFT.
6589 If so, try to merge the shifts into a SIGN_EXTEND. We could
6590 also do this for some cases of SIGN_EXTRACT, but it doesn't
6591 seem worth the effort; the case checked for occurs on Alpha. */
6592
6593 if (GET_RTX_CLASS (GET_CODE (lhs)) != 'o'
6594 && ! (GET_CODE (lhs) == SUBREG
6595 && (GET_RTX_CLASS (GET_CODE (SUBREG_REG (lhs))) == 'o'))
6596 && GET_CODE (rhs) == CONST_INT
6597 && INTVAL (rhs) < HOST_BITS_PER_WIDE_INT
6598 && (new = extract_left_shift (lhs, INTVAL (rhs))) != 0)
6599 new = make_extraction (mode, make_compound_operation (new, next_code),
6600 0, NULL_RTX, mode_width - INTVAL (rhs),
6601 code == LSHIFTRT, 0, in_code == COMPARE);
6602
6603 break;
6604
6605 case SUBREG:
6606 /* Call ourselves recursively on the inner expression. If we are
6607 narrowing the object and it has a different RTL code from
6608 what it originally did, do this SUBREG as a force_to_mode. */
6609
6610 tem = make_compound_operation (SUBREG_REG (x), in_code);
6611 if (GET_CODE (tem) != GET_CODE (SUBREG_REG (x))
6612 && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (tem))
6613 && subreg_lowpart_p (x))
6614 {
6615 rtx newer = force_to_mode (tem, mode, ~(HOST_WIDE_INT) 0,
6616 NULL_RTX, 0);
6617
6618 /* If we have something other than a SUBREG, we might have
6619 done an expansion, so rerun ourselves. */
6620 if (GET_CODE (newer) != SUBREG)
6621 newer = make_compound_operation (newer, in_code);
6622
6623 return newer;
6624 }
6625
6626 /* If this is a paradoxical subreg, and the new code is a sign or
6627 zero extension, omit the subreg and widen the extension. If it
6628 is a regular subreg, we can still get rid of the subreg by not
6629 widening so much, or in fact removing the extension entirely. */
6630 if ((GET_CODE (tem) == SIGN_EXTEND
6631 || GET_CODE (tem) == ZERO_EXTEND)
6632 && subreg_lowpart_p (x))
6633 {
6634 if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (tem))
6635 || (GET_MODE_SIZE (mode) >
6636 GET_MODE_SIZE (GET_MODE (XEXP (tem, 0)))))
6637 {
6638 if (! SCALAR_INT_MODE_P (mode))
6639 break;
6640 tem = gen_rtx_fmt_e (GET_CODE (tem), mode, XEXP (tem, 0));
6641 }
6642 else
6643 tem = gen_lowpart_for_combine (mode, XEXP (tem, 0));
6644 return tem;
6645 }
6646 break;
6647
6648 default:
6649 break;
6650 }
6651
6652 if (new)
6653 {
6654 x = gen_lowpart_for_combine (mode, new);
6655 code = GET_CODE (x);
6656 }
6657
6658 /* Now recursively process each operand of this operation. */
6659 fmt = GET_RTX_FORMAT (code);
6660 for (i = 0; i < GET_RTX_LENGTH (code); i++)
6661 if (fmt[i] == 'e')
6662 {
6663 new = make_compound_operation (XEXP (x, i), next_code);
6664 SUBST (XEXP (x, i), new);
6665 }
6666
6667 return x;
6668 }
6669
6670 /* Given M see if it is a value that would select a field of bits
6671 within an item, but not the entire word. Return -1 if not.
6672 Otherwise, return the starting position of the field, where 0 is the
6673 low-order bit.
6674
6675 *PLEN is set to the length of the field. */
6676
6677 static int
get_pos_from_mask(unsigned HOST_WIDE_INT m,unsigned HOST_WIDE_INT * plen)6678 get_pos_from_mask (unsigned HOST_WIDE_INT m, unsigned HOST_WIDE_INT *plen)
6679 {
6680 /* Get the bit number of the first 1 bit from the right, -1 if none. */
6681 int pos = exact_log2 (m & -m);
6682 int len;
6683
6684 if (pos < 0)
6685 return -1;
6686
6687 /* Now shift off the low-order zero bits and see if we have a power of
6688 two minus 1. */
6689 len = exact_log2 ((m >> pos) + 1);
6690
6691 if (len <= 0)
6692 return -1;
6693
6694 *plen = len;
6695 return pos;
6696 }
6697
6698 /* See if X can be simplified knowing that we will only refer to it in
6699 MODE and will only refer to those bits that are nonzero in MASK.
6700 If other bits are being computed or if masking operations are done
6701 that select a superset of the bits in MASK, they can sometimes be
6702 ignored.
6703
6704 Return a possibly simplified expression, but always convert X to
6705 MODE. If X is a CONST_INT, AND the CONST_INT with MASK.
6706
6707 Also, if REG is nonzero and X is a register equal in value to REG,
6708 replace X with REG.
6709
6710 If JUST_SELECT is nonzero, don't optimize by noticing that bits in MASK
6711 are all off in X. This is used when X will be complemented, by either
6712 NOT, NEG, or XOR. */
6713
6714 static rtx
force_to_mode(rtx x,enum machine_mode mode,unsigned HOST_WIDE_INT mask,rtx reg,int just_select)6715 force_to_mode (rtx x, enum machine_mode mode, unsigned HOST_WIDE_INT mask,
6716 rtx reg, int just_select)
6717 {
6718 enum rtx_code code = GET_CODE (x);
6719 int next_select = just_select || code == XOR || code == NOT || code == NEG;
6720 enum machine_mode op_mode;
6721 unsigned HOST_WIDE_INT fuller_mask, nonzero;
6722 rtx op0, op1, temp;
6723
6724 /* If this is a CALL or ASM_OPERANDS, don't do anything. Some of the
6725 code below will do the wrong thing since the mode of such an
6726 expression is VOIDmode.
6727
6728 Also do nothing if X is a CLOBBER; this can happen if X was
6729 the return value from a call to gen_lowpart_for_combine. */
6730 if (code == CALL || code == ASM_OPERANDS || code == CLOBBER)
6731 return x;
6732
6733 /* We want to perform the operation is its present mode unless we know
6734 that the operation is valid in MODE, in which case we do the operation
6735 in MODE. */
6736 op_mode = ((GET_MODE_CLASS (mode) == GET_MODE_CLASS (GET_MODE (x))
6737 && have_insn_for (code, mode))
6738 ? mode : GET_MODE (x));
6739
6740 /* It is not valid to do a right-shift in a narrower mode
6741 than the one it came in with. */
6742 if ((code == LSHIFTRT || code == ASHIFTRT)
6743 && GET_MODE_BITSIZE (mode) < GET_MODE_BITSIZE (GET_MODE (x)))
6744 op_mode = GET_MODE (x);
6745
6746 /* Truncate MASK to fit OP_MODE. */
6747 if (op_mode)
6748 mask &= GET_MODE_MASK (op_mode);
6749
6750 /* When we have an arithmetic operation, or a shift whose count we
6751 do not know, we need to assume that all bits up to the highest-order
6752 bit in MASK will be needed. This is how we form such a mask. */
6753 if (mask & ((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT - 1)))
6754 fuller_mask = ~(unsigned HOST_WIDE_INT) 0;
6755 else
6756 fuller_mask = (((unsigned HOST_WIDE_INT) 1 << (floor_log2 (mask) + 1))
6757 - 1);
6758
6759 /* Determine what bits of X are guaranteed to be (non)zero. */
6760 nonzero = nonzero_bits (x, mode);
6761
6762 /* If none of the bits in X are needed, return a zero. */
6763 if (! just_select && (nonzero & mask) == 0)
6764 x = const0_rtx;
6765
6766 /* If X is a CONST_INT, return a new one. Do this here since the
6767 test below will fail. */
6768 if (GET_CODE (x) == CONST_INT)
6769 {
6770 if (SCALAR_INT_MODE_P (mode))
6771 return gen_int_mode (INTVAL (x) & mask, mode);
6772 else
6773 {
6774 x = GEN_INT (INTVAL (x) & mask);
6775 return gen_lowpart_common (mode, x);
6776 }
6777 }
6778
6779 /* If X is narrower than MODE and we want all the bits in X's mode, just
6780 get X in the proper mode. */
6781 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (mode)
6782 && (GET_MODE_MASK (GET_MODE (x)) & ~mask) == 0)
6783 return gen_lowpart_for_combine (mode, x);
6784
6785 /* If we aren't changing the mode, X is not a SUBREG, and all zero bits in
6786 MASK are already known to be zero in X, we need not do anything. */
6787 if (GET_MODE (x) == mode && code != SUBREG && (~mask & nonzero) == 0)
6788 return x;
6789
6790 switch (code)
6791 {
6792 case CLOBBER:
6793 /* If X is a (clobber (const_int)), return it since we know we are
6794 generating something that won't match. */
6795 return x;
6796
6797 case USE:
6798 /* X is a (use (mem ..)) that was made from a bit-field extraction that
6799 spanned the boundary of the MEM. If we are now masking so it is
6800 within that boundary, we don't need the USE any more. */
6801 if (! BITS_BIG_ENDIAN
6802 && (mask & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0)))) == 0)
6803 return force_to_mode (XEXP (x, 0), mode, mask, reg, next_select);
6804 break;
6805
6806 case SIGN_EXTEND:
6807 case ZERO_EXTEND:
6808 case ZERO_EXTRACT:
6809 case SIGN_EXTRACT:
6810 x = expand_compound_operation (x);
6811 if (GET_CODE (x) != code)
6812 return force_to_mode (x, mode, mask, reg, next_select);
6813 break;
6814
6815 case REG:
6816 if (reg != 0 && (rtx_equal_p (get_last_value (reg), x)
6817 || rtx_equal_p (reg, get_last_value (x))))
6818 x = reg;
6819 break;
6820
6821 case SUBREG:
6822 if (subreg_lowpart_p (x)
6823 /* We can ignore the effect of this SUBREG if it narrows the mode or
6824 if the constant masks to zero all the bits the mode doesn't
6825 have. */
6826 && ((GET_MODE_SIZE (GET_MODE (x))
6827 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
6828 || (0 == (mask
6829 & GET_MODE_MASK (GET_MODE (x))
6830 & ~GET_MODE_MASK (GET_MODE (SUBREG_REG (x)))))))
6831 return force_to_mode (SUBREG_REG (x), mode, mask, reg, next_select);
6832 break;
6833
6834 case AND:
6835 /* If this is an AND with a constant, convert it into an AND
6836 whose constant is the AND of that constant with MASK. If it
6837 remains an AND of MASK, delete it since it is redundant. */
6838
6839 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
6840 {
6841 x = simplify_and_const_int (x, op_mode, XEXP (x, 0),
6842 mask & INTVAL (XEXP (x, 1)));
6843
6844 /* If X is still an AND, see if it is an AND with a mask that
6845 is just some low-order bits. If so, and it is MASK, we don't
6846 need it. */
6847
6848 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT
6849 && ((INTVAL (XEXP (x, 1)) & GET_MODE_MASK (GET_MODE (x)))
6850 == mask))
6851 x = XEXP (x, 0);
6852
6853 /* If it remains an AND, try making another AND with the bits
6854 in the mode mask that aren't in MASK turned on. If the
6855 constant in the AND is wide enough, this might make a
6856 cheaper constant. */
6857
6858 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT
6859 && GET_MODE_MASK (GET_MODE (x)) != mask
6860 && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT)
6861 {
6862 HOST_WIDE_INT cval = (INTVAL (XEXP (x, 1))
6863 | (GET_MODE_MASK (GET_MODE (x)) & ~mask));
6864 int width = GET_MODE_BITSIZE (GET_MODE (x));
6865 rtx y;
6866
6867 /* If MODE is narrower that HOST_WIDE_INT and CVAL is a negative
6868 number, sign extend it. */
6869 if (width > 0 && width < HOST_BITS_PER_WIDE_INT
6870 && (cval & ((HOST_WIDE_INT) 1 << (width - 1))) != 0)
6871 cval |= (HOST_WIDE_INT) -1 << width;
6872
6873 y = gen_binary (AND, GET_MODE (x), XEXP (x, 0), GEN_INT (cval));
6874 if (rtx_cost (y, SET) < rtx_cost (x, SET))
6875 x = y;
6876 }
6877
6878 break;
6879 }
6880
6881 goto binop;
6882
6883 case PLUS:
6884 /* In (and (plus FOO C1) M), if M is a mask that just turns off
6885 low-order bits (as in an alignment operation) and FOO is already
6886 aligned to that boundary, mask C1 to that boundary as well.
6887 This may eliminate that PLUS and, later, the AND. */
6888
6889 {
6890 unsigned int width = GET_MODE_BITSIZE (mode);
6891 unsigned HOST_WIDE_INT smask = mask;
6892
6893 /* If MODE is narrower than HOST_WIDE_INT and mask is a negative
6894 number, sign extend it. */
6895
6896 if (width < HOST_BITS_PER_WIDE_INT
6897 && (smask & ((HOST_WIDE_INT) 1 << (width - 1))) != 0)
6898 smask |= (HOST_WIDE_INT) -1 << width;
6899
6900 if (GET_CODE (XEXP (x, 1)) == CONST_INT
6901 && exact_log2 (- smask) >= 0
6902 && (nonzero_bits (XEXP (x, 0), mode) & ~smask) == 0
6903 && (INTVAL (XEXP (x, 1)) & ~smask) != 0)
6904 return force_to_mode (plus_constant (XEXP (x, 0),
6905 (INTVAL (XEXP (x, 1)) & smask)),
6906 mode, smask, reg, next_select);
6907 }
6908
6909 /* ... fall through ... */
6910
6911 case MULT:
6912 /* For PLUS, MINUS and MULT, we need any bits less significant than the
6913 most significant bit in MASK since carries from those bits will
6914 affect the bits we are interested in. */
6915 mask = fuller_mask;
6916 goto binop;
6917
6918 case MINUS:
6919 /* If X is (minus C Y) where C's least set bit is larger than any bit
6920 in the mask, then we may replace with (neg Y). */
6921 if (GET_CODE (XEXP (x, 0)) == CONST_INT
6922 && (((unsigned HOST_WIDE_INT) (INTVAL (XEXP (x, 0))
6923 & -INTVAL (XEXP (x, 0))))
6924 > mask))
6925 {
6926 x = simplify_gen_unary (NEG, GET_MODE (x), XEXP (x, 1),
6927 GET_MODE (x));
6928 return force_to_mode (x, mode, mask, reg, next_select);
6929 }
6930
6931 /* Similarly, if C contains every bit in the fuller_mask, then we may
6932 replace with (not Y). */
6933 if (GET_CODE (XEXP (x, 0)) == CONST_INT
6934 && ((INTVAL (XEXP (x, 0)) | (HOST_WIDE_INT) fuller_mask)
6935 == INTVAL (XEXP (x, 0))))
6936 {
6937 x = simplify_gen_unary (NOT, GET_MODE (x),
6938 XEXP (x, 1), GET_MODE (x));
6939 return force_to_mode (x, mode, mask, reg, next_select);
6940 }
6941
6942 mask = fuller_mask;
6943 goto binop;
6944
6945 case IOR:
6946 case XOR:
6947 /* If X is (ior (lshiftrt FOO C1) C2), try to commute the IOR and
6948 LSHIFTRT so we end up with an (and (lshiftrt (ior ...) ...) ...)
6949 operation which may be a bitfield extraction. Ensure that the
6950 constant we form is not wider than the mode of X. */
6951
6952 if (GET_CODE (XEXP (x, 0)) == LSHIFTRT
6953 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6954 && INTVAL (XEXP (XEXP (x, 0), 1)) >= 0
6955 && INTVAL (XEXP (XEXP (x, 0), 1)) < HOST_BITS_PER_WIDE_INT
6956 && GET_CODE (XEXP (x, 1)) == CONST_INT
6957 && ((INTVAL (XEXP (XEXP (x, 0), 1))
6958 + floor_log2 (INTVAL (XEXP (x, 1))))
6959 < GET_MODE_BITSIZE (GET_MODE (x)))
6960 && (INTVAL (XEXP (x, 1))
6961 & ~nonzero_bits (XEXP (x, 0), GET_MODE (x))) == 0)
6962 {
6963 temp = GEN_INT ((INTVAL (XEXP (x, 1)) & mask)
6964 << INTVAL (XEXP (XEXP (x, 0), 1)));
6965 temp = gen_binary (GET_CODE (x), GET_MODE (x),
6966 XEXP (XEXP (x, 0), 0), temp);
6967 x = gen_binary (LSHIFTRT, GET_MODE (x), temp,
6968 XEXP (XEXP (x, 0), 1));
6969 return force_to_mode (x, mode, mask, reg, next_select);
6970 }
6971
6972 binop:
6973 /* For most binary operations, just propagate into the operation and
6974 change the mode if we have an operation of that mode. */
6975
6976 op0 = gen_lowpart_for_combine (op_mode,
6977 force_to_mode (XEXP (x, 0), mode, mask,
6978 reg, next_select));
6979 op1 = gen_lowpart_for_combine (op_mode,
6980 force_to_mode (XEXP (x, 1), mode, mask,
6981 reg, next_select));
6982
6983 if (op_mode != GET_MODE (x) || op0 != XEXP (x, 0) || op1 != XEXP (x, 1))
6984 x = gen_binary (code, op_mode, op0, op1);
6985 break;
6986
6987 case ASHIFT:
6988 /* For left shifts, do the same, but just for the first operand.
6989 However, we cannot do anything with shifts where we cannot
6990 guarantee that the counts are smaller than the size of the mode
6991 because such a count will have a different meaning in a
6992 wider mode. */
6993
6994 if (! (GET_CODE (XEXP (x, 1)) == CONST_INT
6995 && INTVAL (XEXP (x, 1)) >= 0
6996 && INTVAL (XEXP (x, 1)) < GET_MODE_BITSIZE (mode))
6997 && ! (GET_MODE (XEXP (x, 1)) != VOIDmode
6998 && (nonzero_bits (XEXP (x, 1), GET_MODE (XEXP (x, 1)))
6999 < (unsigned HOST_WIDE_INT) GET_MODE_BITSIZE (mode))))
7000 break;
7001
7002 /* If the shift count is a constant and we can do arithmetic in
7003 the mode of the shift, refine which bits we need. Otherwise, use the
7004 conservative form of the mask. */
7005 if (GET_CODE (XEXP (x, 1)) == CONST_INT
7006 && INTVAL (XEXP (x, 1)) >= 0
7007 && INTVAL (XEXP (x, 1)) < GET_MODE_BITSIZE (op_mode)
7008 && GET_MODE_BITSIZE (op_mode) <= HOST_BITS_PER_WIDE_INT)
7009 mask >>= INTVAL (XEXP (x, 1));
7010 else
7011 mask = fuller_mask;
7012
7013 op0 = gen_lowpart_for_combine (op_mode,
7014 force_to_mode (XEXP (x, 0), op_mode,
7015 mask, reg, next_select));
7016
7017 if (op_mode != GET_MODE (x) || op0 != XEXP (x, 0))
7018 x = gen_binary (code, op_mode, op0, XEXP (x, 1));
7019 break;
7020
7021 case LSHIFTRT:
7022 /* Here we can only do something if the shift count is a constant,
7023 this shift constant is valid for the host, and we can do arithmetic
7024 in OP_MODE. */
7025
7026 if (GET_CODE (XEXP (x, 1)) == CONST_INT
7027 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT
7028 && GET_MODE_BITSIZE (op_mode) <= HOST_BITS_PER_WIDE_INT)
7029 {
7030 rtx inner = XEXP (x, 0);
7031 unsigned HOST_WIDE_INT inner_mask;
7032
7033 /* Select the mask of the bits we need for the shift operand. */
7034 inner_mask = mask << INTVAL (XEXP (x, 1));
7035
7036 /* We can only change the mode of the shift if we can do arithmetic
7037 in the mode of the shift and INNER_MASK is no wider than the
7038 width of OP_MODE. */
7039 if (GET_MODE_BITSIZE (op_mode) > HOST_BITS_PER_WIDE_INT
7040 || (inner_mask & ~GET_MODE_MASK (op_mode)) != 0)
7041 op_mode = GET_MODE (x);
7042
7043 inner = force_to_mode (inner, op_mode, inner_mask, reg, next_select);
7044
7045 if (GET_MODE (x) != op_mode || inner != XEXP (x, 0))
7046 x = gen_binary (LSHIFTRT, op_mode, inner, XEXP (x, 1));
7047 }
7048
7049 /* If we have (and (lshiftrt FOO C1) C2) where the combination of the
7050 shift and AND produces only copies of the sign bit (C2 is one less
7051 than a power of two), we can do this with just a shift. */
7052
7053 if (GET_CODE (x) == LSHIFTRT
7054 && GET_CODE (XEXP (x, 1)) == CONST_INT
7055 /* The shift puts one of the sign bit copies in the least significant
7056 bit. */
7057 && ((INTVAL (XEXP (x, 1))
7058 + num_sign_bit_copies (XEXP (x, 0), GET_MODE (XEXP (x, 0))))
7059 >= GET_MODE_BITSIZE (GET_MODE (x)))
7060 && exact_log2 (mask + 1) >= 0
7061 /* Number of bits left after the shift must be more than the mask
7062 needs. */
7063 && ((INTVAL (XEXP (x, 1)) + exact_log2 (mask + 1))
7064 <= GET_MODE_BITSIZE (GET_MODE (x)))
7065 /* Must be more sign bit copies than the mask needs. */
7066 && ((int) num_sign_bit_copies (XEXP (x, 0), GET_MODE (XEXP (x, 0)))
7067 >= exact_log2 (mask + 1)))
7068 x = gen_binary (LSHIFTRT, GET_MODE (x), XEXP (x, 0),
7069 GEN_INT (GET_MODE_BITSIZE (GET_MODE (x))
7070 - exact_log2 (mask + 1)));
7071
7072 goto shiftrt;
7073
7074 case ASHIFTRT:
7075 /* If we are just looking for the sign bit, we don't need this shift at
7076 all, even if it has a variable count. */
7077 if (GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT
7078 && (mask == ((unsigned HOST_WIDE_INT) 1
7079 << (GET_MODE_BITSIZE (GET_MODE (x)) - 1))))
7080 return force_to_mode (XEXP (x, 0), mode, mask, reg, next_select);
7081
7082 /* If this is a shift by a constant, get a mask that contains those bits
7083 that are not copies of the sign bit. We then have two cases: If
7084 MASK only includes those bits, this can be a logical shift, which may
7085 allow simplifications. If MASK is a single-bit field not within
7086 those bits, we are requesting a copy of the sign bit and hence can
7087 shift the sign bit to the appropriate location. */
7088
7089 if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0
7090 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT)
7091 {
7092 int i = -1;
7093
7094 /* If the considered data is wider than HOST_WIDE_INT, we can't
7095 represent a mask for all its bits in a single scalar.
7096 But we only care about the lower bits, so calculate these. */
7097
7098 if (GET_MODE_BITSIZE (GET_MODE (x)) > HOST_BITS_PER_WIDE_INT)
7099 {
7100 nonzero = ~(HOST_WIDE_INT) 0;
7101
7102 /* GET_MODE_BITSIZE (GET_MODE (x)) - INTVAL (XEXP (x, 1))
7103 is the number of bits a full-width mask would have set.
7104 We need only shift if these are fewer than nonzero can
7105 hold. If not, we must keep all bits set in nonzero. */
7106
7107 if (GET_MODE_BITSIZE (GET_MODE (x)) - INTVAL (XEXP (x, 1))
7108 < HOST_BITS_PER_WIDE_INT)
7109 nonzero >>= INTVAL (XEXP (x, 1))
7110 + HOST_BITS_PER_WIDE_INT
7111 - GET_MODE_BITSIZE (GET_MODE (x)) ;
7112 }
7113 else
7114 {
7115 nonzero = GET_MODE_MASK (GET_MODE (x));
7116 nonzero >>= INTVAL (XEXP (x, 1));
7117 }
7118
7119 if ((mask & ~nonzero) == 0
7120 || (i = exact_log2 (mask)) >= 0)
7121 {
7122 x = simplify_shift_const
7123 (x, LSHIFTRT, GET_MODE (x), XEXP (x, 0),
7124 i < 0 ? INTVAL (XEXP (x, 1))
7125 : GET_MODE_BITSIZE (GET_MODE (x)) - 1 - i);
7126
7127 if (GET_CODE (x) != ASHIFTRT)
7128 return force_to_mode (x, mode, mask, reg, next_select);
7129 }
7130 }
7131
7132 /* If MASK is 1, convert this to an LSHIFTRT. This can be done
7133 even if the shift count isn't a constant. */
7134 if (mask == 1)
7135 x = gen_binary (LSHIFTRT, GET_MODE (x), XEXP (x, 0), XEXP (x, 1));
7136
7137 shiftrt:
7138
7139 /* If this is a zero- or sign-extension operation that just affects bits
7140 we don't care about, remove it. Be sure the call above returned
7141 something that is still a shift. */
7142
7143 if ((GET_CODE (x) == LSHIFTRT || GET_CODE (x) == ASHIFTRT)
7144 && GET_CODE (XEXP (x, 1)) == CONST_INT
7145 && INTVAL (XEXP (x, 1)) >= 0
7146 && (INTVAL (XEXP (x, 1))
7147 <= GET_MODE_BITSIZE (GET_MODE (x)) - (floor_log2 (mask) + 1))
7148 && GET_CODE (XEXP (x, 0)) == ASHIFT
7149 && XEXP (XEXP (x, 0), 1) == XEXP (x, 1))
7150 return force_to_mode (XEXP (XEXP (x, 0), 0), mode, mask,
7151 reg, next_select);
7152
7153 break;
7154
7155 case ROTATE:
7156 case ROTATERT:
7157 /* If the shift count is constant and we can do computations
7158 in the mode of X, compute where the bits we care about are.
7159 Otherwise, we can't do anything. Don't change the mode of
7160 the shift or propagate MODE into the shift, though. */
7161 if (GET_CODE (XEXP (x, 1)) == CONST_INT
7162 && INTVAL (XEXP (x, 1)) >= 0)
7163 {
7164 temp = simplify_binary_operation (code == ROTATE ? ROTATERT : ROTATE,
7165 GET_MODE (x), GEN_INT (mask),
7166 XEXP (x, 1));
7167 if (temp && GET_CODE (temp) == CONST_INT)
7168 SUBST (XEXP (x, 0),
7169 force_to_mode (XEXP (x, 0), GET_MODE (x),
7170 INTVAL (temp), reg, next_select));
7171 }
7172 break;
7173
7174 case NEG:
7175 /* If we just want the low-order bit, the NEG isn't needed since it
7176 won't change the low-order bit. */
7177 if (mask == 1)
7178 return force_to_mode (XEXP (x, 0), mode, mask, reg, just_select);
7179
7180 /* We need any bits less significant than the most significant bit in
7181 MASK since carries from those bits will affect the bits we are
7182 interested in. */
7183 mask = fuller_mask;
7184 goto unop;
7185
7186 case NOT:
7187 /* (not FOO) is (xor FOO CONST), so if FOO is an LSHIFTRT, we can do the
7188 same as the XOR case above. Ensure that the constant we form is not
7189 wider than the mode of X. */
7190
7191 if (GET_CODE (XEXP (x, 0)) == LSHIFTRT
7192 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
7193 && INTVAL (XEXP (XEXP (x, 0), 1)) >= 0
7194 && (INTVAL (XEXP (XEXP (x, 0), 1)) + floor_log2 (mask)
7195 < GET_MODE_BITSIZE (GET_MODE (x)))
7196 && INTVAL (XEXP (XEXP (x, 0), 1)) < HOST_BITS_PER_WIDE_INT)
7197 {
7198 temp = gen_int_mode (mask << INTVAL (XEXP (XEXP (x, 0), 1)),
7199 GET_MODE (x));
7200 temp = gen_binary (XOR, GET_MODE (x), XEXP (XEXP (x, 0), 0), temp);
7201 x = gen_binary (LSHIFTRT, GET_MODE (x), temp, XEXP (XEXP (x, 0), 1));
7202
7203 return force_to_mode (x, mode, mask, reg, next_select);
7204 }
7205
7206 /* (and (not FOO) CONST) is (not (or FOO (not CONST))), so we must
7207 use the full mask inside the NOT. */
7208 mask = fuller_mask;
7209
7210 unop:
7211 op0 = gen_lowpart_for_combine (op_mode,
7212 force_to_mode (XEXP (x, 0), mode, mask,
7213 reg, next_select));
7214 if (op_mode != GET_MODE (x) || op0 != XEXP (x, 0))
7215 x = simplify_gen_unary (code, op_mode, op0, op_mode);
7216 break;
7217
7218 case NE:
7219 /* (and (ne FOO 0) CONST) can be (and FOO CONST) if CONST is included
7220 in STORE_FLAG_VALUE and FOO has a single bit that might be nonzero,
7221 which is equal to STORE_FLAG_VALUE. */
7222 if ((mask & ~STORE_FLAG_VALUE) == 0 && XEXP (x, 1) == const0_rtx
7223 && exact_log2 (nonzero_bits (XEXP (x, 0), mode)) >= 0
7224 && (nonzero_bits (XEXP (x, 0), mode)
7225 == (unsigned HOST_WIDE_INT) STORE_FLAG_VALUE))
7226 return force_to_mode (XEXP (x, 0), mode, mask, reg, next_select);
7227
7228 break;
7229
7230 case IF_THEN_ELSE:
7231 /* We have no way of knowing if the IF_THEN_ELSE can itself be
7232 written in a narrower mode. We play it safe and do not do so. */
7233
7234 SUBST (XEXP (x, 1),
7235 gen_lowpart_for_combine (GET_MODE (x),
7236 force_to_mode (XEXP (x, 1), mode,
7237 mask, reg, next_select)));
7238 SUBST (XEXP (x, 2),
7239 gen_lowpart_for_combine (GET_MODE (x),
7240 force_to_mode (XEXP (x, 2), mode,
7241 mask, reg, next_select)));
7242 break;
7243
7244 default:
7245 break;
7246 }
7247
7248 /* Ensure we return a value of the proper mode. */
7249 return gen_lowpart_for_combine (mode, x);
7250 }
7251
7252 /* Return nonzero if X is an expression that has one of two values depending on
7253 whether some other value is zero or nonzero. In that case, we return the
7254 value that is being tested, *PTRUE is set to the value if the rtx being
7255 returned has a nonzero value, and *PFALSE is set to the other alternative.
7256
7257 If we return zero, we set *PTRUE and *PFALSE to X. */
7258
7259 static rtx
if_then_else_cond(rtx x,rtx * ptrue,rtx * pfalse)7260 if_then_else_cond (rtx x, rtx *ptrue, rtx *pfalse)
7261 {
7262 enum machine_mode mode = GET_MODE (x);
7263 enum rtx_code code = GET_CODE (x);
7264 rtx cond0, cond1, true0, true1, false0, false1;
7265 unsigned HOST_WIDE_INT nz;
7266
7267 /* If we are comparing a value against zero, we are done. */
7268 if ((code == NE || code == EQ)
7269 && XEXP (x, 1) == const0_rtx)
7270 {
7271 *ptrue = (code == NE) ? const_true_rtx : const0_rtx;
7272 *pfalse = (code == NE) ? const0_rtx : const_true_rtx;
7273 return XEXP (x, 0);
7274 }
7275
7276 /* If this is a unary operation whose operand has one of two values, apply
7277 our opcode to compute those values. */
7278 else if (GET_RTX_CLASS (code) == '1'
7279 && (cond0 = if_then_else_cond (XEXP (x, 0), &true0, &false0)) != 0)
7280 {
7281 *ptrue = simplify_gen_unary (code, mode, true0, GET_MODE (XEXP (x, 0)));
7282 *pfalse = simplify_gen_unary (code, mode, false0,
7283 GET_MODE (XEXP (x, 0)));
7284 return cond0;
7285 }
7286
7287 /* If this is a COMPARE, do nothing, since the IF_THEN_ELSE we would
7288 make can't possibly match and would suppress other optimizations. */
7289 else if (code == COMPARE)
7290 ;
7291
7292 /* If this is a binary operation, see if either side has only one of two
7293 values. If either one does or if both do and they are conditional on
7294 the same value, compute the new true and false values. */
7295 else if (GET_RTX_CLASS (code) == 'c' || GET_RTX_CLASS (code) == '2'
7296 || GET_RTX_CLASS (code) == '<')
7297 {
7298 cond0 = if_then_else_cond (XEXP (x, 0), &true0, &false0);
7299 cond1 = if_then_else_cond (XEXP (x, 1), &true1, &false1);
7300
7301 if ((cond0 != 0 || cond1 != 0)
7302 && ! (cond0 != 0 && cond1 != 0 && ! rtx_equal_p (cond0, cond1)))
7303 {
7304 /* If if_then_else_cond returned zero, then true/false are the
7305 same rtl. We must copy one of them to prevent invalid rtl
7306 sharing. */
7307 if (cond0 == 0)
7308 true0 = copy_rtx (true0);
7309 else if (cond1 == 0)
7310 true1 = copy_rtx (true1);
7311
7312 *ptrue = gen_binary (code, mode, true0, true1);
7313 *pfalse = gen_binary (code, mode, false0, false1);
7314 return cond0 ? cond0 : cond1;
7315 }
7316
7317 /* See if we have PLUS, IOR, XOR, MINUS or UMAX, where one of the
7318 operands is zero when the other is nonzero, and vice-versa,
7319 and STORE_FLAG_VALUE is 1 or -1. */
7320
7321 if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
7322 && (code == PLUS || code == IOR || code == XOR || code == MINUS
7323 || code == UMAX)
7324 && GET_CODE (XEXP (x, 0)) == MULT && GET_CODE (XEXP (x, 1)) == MULT)
7325 {
7326 rtx op0 = XEXP (XEXP (x, 0), 1);
7327 rtx op1 = XEXP (XEXP (x, 1), 1);
7328
7329 cond0 = XEXP (XEXP (x, 0), 0);
7330 cond1 = XEXP (XEXP (x, 1), 0);
7331
7332 if (GET_RTX_CLASS (GET_CODE (cond0)) == '<'
7333 && GET_RTX_CLASS (GET_CODE (cond1)) == '<'
7334 && ((GET_CODE (cond0) == combine_reversed_comparison_code (cond1)
7335 && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 0))
7336 && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 1)))
7337 || ((swap_condition (GET_CODE (cond0))
7338 == combine_reversed_comparison_code (cond1))
7339 && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 1))
7340 && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 0))))
7341 && ! side_effects_p (x))
7342 {
7343 *ptrue = gen_binary (MULT, mode, op0, const_true_rtx);
7344 *pfalse = gen_binary (MULT, mode,
7345 (code == MINUS
7346 ? simplify_gen_unary (NEG, mode, op1,
7347 mode)
7348 : op1),
7349 const_true_rtx);
7350 return cond0;
7351 }
7352 }
7353
7354 /* Similarly for MULT, AND and UMIN, except that for these the result
7355 is always zero. */
7356 if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
7357 && (code == MULT || code == AND || code == UMIN)
7358 && GET_CODE (XEXP (x, 0)) == MULT && GET_CODE (XEXP (x, 1)) == MULT)
7359 {
7360 cond0 = XEXP (XEXP (x, 0), 0);
7361 cond1 = XEXP (XEXP (x, 1), 0);
7362
7363 if (GET_RTX_CLASS (GET_CODE (cond0)) == '<'
7364 && GET_RTX_CLASS (GET_CODE (cond1)) == '<'
7365 && ((GET_CODE (cond0) == combine_reversed_comparison_code (cond1)
7366 && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 0))
7367 && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 1)))
7368 || ((swap_condition (GET_CODE (cond0))
7369 == combine_reversed_comparison_code (cond1))
7370 && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 1))
7371 && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 0))))
7372 && ! side_effects_p (x))
7373 {
7374 *ptrue = *pfalse = const0_rtx;
7375 return cond0;
7376 }
7377 }
7378 }
7379
7380 else if (code == IF_THEN_ELSE)
7381 {
7382 /* If we have IF_THEN_ELSE already, extract the condition and
7383 canonicalize it if it is NE or EQ. */
7384 cond0 = XEXP (x, 0);
7385 *ptrue = XEXP (x, 1), *pfalse = XEXP (x, 2);
7386 if (GET_CODE (cond0) == NE && XEXP (cond0, 1) == const0_rtx)
7387 return XEXP (cond0, 0);
7388 else if (GET_CODE (cond0) == EQ && XEXP (cond0, 1) == const0_rtx)
7389 {
7390 *ptrue = XEXP (x, 2), *pfalse = XEXP (x, 1);
7391 return XEXP (cond0, 0);
7392 }
7393 else
7394 return cond0;
7395 }
7396
7397 /* If X is a SUBREG, we can narrow both the true and false values
7398 if the inner expression, if there is a condition. */
7399 else if (code == SUBREG
7400 && 0 != (cond0 = if_then_else_cond (SUBREG_REG (x),
7401 &true0, &false0)))
7402 {
7403 true0 = simplify_gen_subreg (mode, true0,
7404 GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
7405 false0 = simplify_gen_subreg (mode, false0,
7406 GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
7407 if (true0 && false0)
7408 {
7409 *ptrue = true0;
7410 *pfalse = false0;
7411 return cond0;
7412 }
7413 }
7414
7415 /* If X is a constant, this isn't special and will cause confusions
7416 if we treat it as such. Likewise if it is equivalent to a constant. */
7417 else if (CONSTANT_P (x)
7418 || ((cond0 = get_last_value (x)) != 0 && CONSTANT_P (cond0)))
7419 ;
7420
7421 /* If we're in BImode, canonicalize on 0 and STORE_FLAG_VALUE, as that
7422 will be least confusing to the rest of the compiler. */
7423 else if (mode == BImode)
7424 {
7425 *ptrue = GEN_INT (STORE_FLAG_VALUE), *pfalse = const0_rtx;
7426 return x;
7427 }
7428
7429 /* If X is known to be either 0 or -1, those are the true and
7430 false values when testing X. */
7431 else if (x == constm1_rtx || x == const0_rtx
7432 || (mode != VOIDmode
7433 && num_sign_bit_copies (x, mode) == GET_MODE_BITSIZE (mode)))
7434 {
7435 *ptrue = constm1_rtx, *pfalse = const0_rtx;
7436 return x;
7437 }
7438
7439 /* Likewise for 0 or a single bit. */
7440 else if (SCALAR_INT_MODE_P (mode)
7441 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
7442 && exact_log2 (nz = nonzero_bits (x, mode)) >= 0)
7443 {
7444 *ptrue = gen_int_mode (nz, mode), *pfalse = const0_rtx;
7445 return x;
7446 }
7447
7448 /* Otherwise fail; show no condition with true and false values the same. */
7449 *ptrue = *pfalse = x;
7450 return 0;
7451 }
7452
7453 /* Return the value of expression X given the fact that condition COND
7454 is known to be true when applied to REG as its first operand and VAL
7455 as its second. X is known to not be shared and so can be modified in
7456 place.
7457
7458 We only handle the simplest cases, and specifically those cases that
7459 arise with IF_THEN_ELSE expressions. */
7460
7461 static rtx
known_cond(rtx x,enum rtx_code cond,rtx reg,rtx val)7462 known_cond (rtx x, enum rtx_code cond, rtx reg, rtx val)
7463 {
7464 enum rtx_code code = GET_CODE (x);
7465 rtx temp;
7466 const char *fmt;
7467 int i, j;
7468
7469 if (side_effects_p (x))
7470 return x;
7471
7472 /* If either operand of the condition is a floating point value,
7473 then we have to avoid collapsing an EQ comparison. */
7474 if (cond == EQ
7475 && rtx_equal_p (x, reg)
7476 && ! FLOAT_MODE_P (GET_MODE (x))
7477 && ! FLOAT_MODE_P (GET_MODE (val)))
7478 return val;
7479
7480 if (cond == UNEQ && rtx_equal_p (x, reg))
7481 return val;
7482
7483 /* If X is (abs REG) and we know something about REG's relationship
7484 with zero, we may be able to simplify this. */
7485
7486 if (code == ABS && rtx_equal_p (XEXP (x, 0), reg) && val == const0_rtx)
7487 switch (cond)
7488 {
7489 case GE: case GT: case EQ:
7490 return XEXP (x, 0);
7491 case LT: case LE:
7492 return simplify_gen_unary (NEG, GET_MODE (XEXP (x, 0)),
7493 XEXP (x, 0),
7494 GET_MODE (XEXP (x, 0)));
7495 default:
7496 break;
7497 }
7498
7499 /* The only other cases we handle are MIN, MAX, and comparisons if the
7500 operands are the same as REG and VAL. */
7501
7502 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == 'c')
7503 {
7504 if (rtx_equal_p (XEXP (x, 0), val))
7505 cond = swap_condition (cond), temp = val, val = reg, reg = temp;
7506
7507 if (rtx_equal_p (XEXP (x, 0), reg) && rtx_equal_p (XEXP (x, 1), val))
7508 {
7509 if (GET_RTX_CLASS (code) == '<')
7510 {
7511 if (comparison_dominates_p (cond, code))
7512 return const_true_rtx;
7513
7514 code = combine_reversed_comparison_code (x);
7515 if (code != UNKNOWN
7516 && comparison_dominates_p (cond, code))
7517 return const0_rtx;
7518 else
7519 return x;
7520 }
7521 else if (code == SMAX || code == SMIN
7522 || code == UMIN || code == UMAX)
7523 {
7524 int unsignedp = (code == UMIN || code == UMAX);
7525
7526 /* Do not reverse the condition when it is NE or EQ.
7527 This is because we cannot conclude anything about
7528 the value of 'SMAX (x, y)' when x is not equal to y,
7529 but we can when x equals y. */
7530 if ((code == SMAX || code == UMAX)
7531 && ! (cond == EQ || cond == NE))
7532 cond = reverse_condition (cond);
7533
7534 switch (cond)
7535 {
7536 case GE: case GT:
7537 return unsignedp ? x : XEXP (x, 1);
7538 case LE: case LT:
7539 return unsignedp ? x : XEXP (x, 0);
7540 case GEU: case GTU:
7541 return unsignedp ? XEXP (x, 1) : x;
7542 case LEU: case LTU:
7543 return unsignedp ? XEXP (x, 0) : x;
7544 default:
7545 break;
7546 }
7547 }
7548 }
7549 }
7550 else if (code == SUBREG)
7551 {
7552 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (x));
7553 rtx new, r = known_cond (SUBREG_REG (x), cond, reg, val);
7554
7555 if (SUBREG_REG (x) != r)
7556 {
7557 /* We must simplify subreg here, before we lose track of the
7558 original inner_mode. */
7559 new = simplify_subreg (GET_MODE (x), r,
7560 inner_mode, SUBREG_BYTE (x));
7561 if (new)
7562 return new;
7563 else
7564 SUBST (SUBREG_REG (x), r);
7565 }
7566
7567 return x;
7568 }
7569 /* We don't have to handle SIGN_EXTEND here, because even in the
7570 case of replacing something with a modeless CONST_INT, a
7571 CONST_INT is already (supposed to be) a valid sign extension for
7572 its narrower mode, which implies it's already properly
7573 sign-extended for the wider mode. Now, for ZERO_EXTEND, the
7574 story is different. */
7575 else if (code == ZERO_EXTEND)
7576 {
7577 enum machine_mode inner_mode = GET_MODE (XEXP (x, 0));
7578 rtx new, r = known_cond (XEXP (x, 0), cond, reg, val);
7579
7580 if (XEXP (x, 0) != r)
7581 {
7582 /* We must simplify the zero_extend here, before we lose
7583 track of the original inner_mode. */
7584 new = simplify_unary_operation (ZERO_EXTEND, GET_MODE (x),
7585 r, inner_mode);
7586 if (new)
7587 return new;
7588 else
7589 SUBST (XEXP (x, 0), r);
7590 }
7591
7592 return x;
7593 }
7594
7595 fmt = GET_RTX_FORMAT (code);
7596 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7597 {
7598 if (fmt[i] == 'e')
7599 SUBST (XEXP (x, i), known_cond (XEXP (x, i), cond, reg, val));
7600 else if (fmt[i] == 'E')
7601 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7602 SUBST (XVECEXP (x, i, j), known_cond (XVECEXP (x, i, j),
7603 cond, reg, val));
7604 }
7605
7606 return x;
7607 }
7608
7609 /* See if X and Y are equal for the purposes of seeing if we can rewrite an
7610 assignment as a field assignment. */
7611
7612 static int
rtx_equal_for_field_assignment_p(rtx x,rtx y)7613 rtx_equal_for_field_assignment_p (rtx x, rtx y)
7614 {
7615 if (x == y || rtx_equal_p (x, y))
7616 return 1;
7617
7618 if (x == 0 || y == 0 || GET_MODE (x) != GET_MODE (y))
7619 return 0;
7620
7621 /* Check for a paradoxical SUBREG of a MEM compared with the MEM.
7622 Note that all SUBREGs of MEM are paradoxical; otherwise they
7623 would have been rewritten. */
7624 if (GET_CODE (x) == MEM && GET_CODE (y) == SUBREG
7625 && GET_CODE (SUBREG_REG (y)) == MEM
7626 && rtx_equal_p (SUBREG_REG (y),
7627 gen_lowpart_for_combine (GET_MODE (SUBREG_REG (y)), x)))
7628 return 1;
7629
7630 if (GET_CODE (y) == MEM && GET_CODE (x) == SUBREG
7631 && GET_CODE (SUBREG_REG (x)) == MEM
7632 && rtx_equal_p (SUBREG_REG (x),
7633 gen_lowpart_for_combine (GET_MODE (SUBREG_REG (x)), y)))
7634 return 1;
7635
7636 /* We used to see if get_last_value of X and Y were the same but that's
7637 not correct. In one direction, we'll cause the assignment to have
7638 the wrong destination and in the case, we'll import a register into this
7639 insn that might have already have been dead. So fail if none of the
7640 above cases are true. */
7641 return 0;
7642 }
7643
7644 /* See if X, a SET operation, can be rewritten as a bit-field assignment.
7645 Return that assignment if so.
7646
7647 We only handle the most common cases. */
7648
7649 static rtx
make_field_assignment(rtx x)7650 make_field_assignment (rtx x)
7651 {
7652 rtx dest = SET_DEST (x);
7653 rtx src = SET_SRC (x);
7654 rtx assign;
7655 rtx rhs, lhs;
7656 HOST_WIDE_INT c1;
7657 HOST_WIDE_INT pos;
7658 unsigned HOST_WIDE_INT len;
7659 rtx other;
7660 enum machine_mode mode;
7661
7662 /* If SRC was (and (not (ashift (const_int 1) POS)) DEST), this is
7663 a clear of a one-bit field. We will have changed it to
7664 (and (rotate (const_int -2) POS) DEST), so check for that. Also check
7665 for a SUBREG. */
7666
7667 if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == ROTATE
7668 && GET_CODE (XEXP (XEXP (src, 0), 0)) == CONST_INT
7669 && INTVAL (XEXP (XEXP (src, 0), 0)) == -2
7670 && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1)))
7671 {
7672 assign = make_extraction (VOIDmode, dest, 0, XEXP (XEXP (src, 0), 1),
7673 1, 1, 1, 0);
7674 if (assign != 0)
7675 return gen_rtx_SET (VOIDmode, assign, const0_rtx);
7676 return x;
7677 }
7678
7679 else if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == SUBREG
7680 && subreg_lowpart_p (XEXP (src, 0))
7681 && (GET_MODE_SIZE (GET_MODE (XEXP (src, 0)))
7682 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (src, 0)))))
7683 && GET_CODE (SUBREG_REG (XEXP (src, 0))) == ROTATE
7684 && GET_CODE (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == CONST_INT
7685 && INTVAL (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == -2
7686 && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1)))
7687 {
7688 assign = make_extraction (VOIDmode, dest, 0,
7689 XEXP (SUBREG_REG (XEXP (src, 0)), 1),
7690 1, 1, 1, 0);
7691 if (assign != 0)
7692 return gen_rtx_SET (VOIDmode, assign, const0_rtx);
7693 return x;
7694 }
7695
7696 /* If SRC is (ior (ashift (const_int 1) POS) DEST), this is a set of a
7697 one-bit field. */
7698 else if (GET_CODE (src) == IOR && GET_CODE (XEXP (src, 0)) == ASHIFT
7699 && XEXP (XEXP (src, 0), 0) == const1_rtx
7700 && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1)))
7701 {
7702 assign = make_extraction (VOIDmode, dest, 0, XEXP (XEXP (src, 0), 1),
7703 1, 1, 1, 0);
7704 if (assign != 0)
7705 return gen_rtx_SET (VOIDmode, assign, const1_rtx);
7706 return x;
7707 }
7708
7709 /* The other case we handle is assignments into a constant-position
7710 field. They look like (ior/xor (and DEST C1) OTHER). If C1 represents
7711 a mask that has all one bits except for a group of zero bits and
7712 OTHER is known to have zeros where C1 has ones, this is such an
7713 assignment. Compute the position and length from C1. Shift OTHER
7714 to the appropriate position, force it to the required mode, and
7715 make the extraction. Check for the AND in both operands. */
7716
7717 if (GET_CODE (src) != IOR && GET_CODE (src) != XOR)
7718 return x;
7719
7720 rhs = expand_compound_operation (XEXP (src, 0));
7721 lhs = expand_compound_operation (XEXP (src, 1));
7722
7723 if (GET_CODE (rhs) == AND
7724 && GET_CODE (XEXP (rhs, 1)) == CONST_INT
7725 && rtx_equal_for_field_assignment_p (XEXP (rhs, 0), dest))
7726 c1 = INTVAL (XEXP (rhs, 1)), other = lhs;
7727 else if (GET_CODE (lhs) == AND
7728 && GET_CODE (XEXP (lhs, 1)) == CONST_INT
7729 && rtx_equal_for_field_assignment_p (XEXP (lhs, 0), dest))
7730 c1 = INTVAL (XEXP (lhs, 1)), other = rhs;
7731 else
7732 return x;
7733
7734 pos = get_pos_from_mask ((~c1) & GET_MODE_MASK (GET_MODE (dest)), &len);
7735 if (pos < 0 || pos + len > GET_MODE_BITSIZE (GET_MODE (dest))
7736 || GET_MODE_BITSIZE (GET_MODE (dest)) > HOST_BITS_PER_WIDE_INT
7737 || (c1 & nonzero_bits (other, GET_MODE (dest))) != 0)
7738 return x;
7739
7740 assign = make_extraction (VOIDmode, dest, pos, NULL_RTX, len, 1, 1, 0);
7741 if (assign == 0)
7742 return x;
7743
7744 /* The mode to use for the source is the mode of the assignment, or of
7745 what is inside a possible STRICT_LOW_PART. */
7746 mode = (GET_CODE (assign) == STRICT_LOW_PART
7747 ? GET_MODE (XEXP (assign, 0)) : GET_MODE (assign));
7748
7749 /* Shift OTHER right POS places and make it the source, restricting it
7750 to the proper length and mode. */
7751
7752 src = force_to_mode (simplify_shift_const (NULL_RTX, LSHIFTRT,
7753 GET_MODE (src), other, pos),
7754 mode,
7755 GET_MODE_BITSIZE (mode) >= HOST_BITS_PER_WIDE_INT
7756 ? ~(unsigned HOST_WIDE_INT) 0
7757 : ((unsigned HOST_WIDE_INT) 1 << len) - 1,
7758 dest, 0);
7759
7760 /* If SRC is masked by an AND that does not make a difference in
7761 the value being stored, strip it. */
7762 if (GET_CODE (assign) == ZERO_EXTRACT
7763 && GET_CODE (XEXP (assign, 1)) == CONST_INT
7764 && INTVAL (XEXP (assign, 1)) < HOST_BITS_PER_WIDE_INT
7765 && GET_CODE (src) == AND
7766 && GET_CODE (XEXP (src, 1)) == CONST_INT
7767 && ((unsigned HOST_WIDE_INT) INTVAL (XEXP (src, 1))
7768 == ((unsigned HOST_WIDE_INT) 1 << INTVAL (XEXP (assign, 1))) - 1))
7769 src = XEXP (src, 0);
7770
7771 return gen_rtx_SET (VOIDmode, assign, src);
7772 }
7773
7774 /* See if X is of the form (+ (* a c) (* b c)) and convert to (* (+ a b) c)
7775 if so. */
7776
7777 static rtx
apply_distributive_law(rtx x)7778 apply_distributive_law (rtx x)
7779 {
7780 enum rtx_code code = GET_CODE (x);
7781 enum rtx_code inner_code;
7782 rtx lhs, rhs, other;
7783 rtx tem;
7784
7785 /* Distributivity is not true for floating point as it can change the
7786 value. So we don't do it unless -funsafe-math-optimizations. */
7787 if (FLOAT_MODE_P (GET_MODE (x))
7788 && ! flag_unsafe_math_optimizations)
7789 return x;
7790
7791 /* The outer operation can only be one of the following: */
7792 if (code != IOR && code != AND && code != XOR
7793 && code != PLUS && code != MINUS)
7794 return x;
7795
7796 lhs = XEXP (x, 0);
7797 rhs = XEXP (x, 1);
7798
7799 /* If either operand is a primitive we can't do anything, so get out
7800 fast. */
7801 if (GET_RTX_CLASS (GET_CODE (lhs)) == 'o'
7802 || GET_RTX_CLASS (GET_CODE (rhs)) == 'o')
7803 return x;
7804
7805 lhs = expand_compound_operation (lhs);
7806 rhs = expand_compound_operation (rhs);
7807 inner_code = GET_CODE (lhs);
7808 if (inner_code != GET_CODE (rhs))
7809 return x;
7810
7811 /* See if the inner and outer operations distribute. */
7812 switch (inner_code)
7813 {
7814 case LSHIFTRT:
7815 case ASHIFTRT:
7816 case AND:
7817 case IOR:
7818 /* These all distribute except over PLUS. */
7819 if (code == PLUS || code == MINUS)
7820 return x;
7821 break;
7822
7823 case MULT:
7824 if (code != PLUS && code != MINUS)
7825 return x;
7826 break;
7827
7828 case ASHIFT:
7829 /* This is also a multiply, so it distributes over everything. */
7830 break;
7831
7832 case SUBREG:
7833 /* Non-paradoxical SUBREGs distributes over all operations, provided
7834 the inner modes and byte offsets are the same, this is an extraction
7835 of a low-order part, we don't convert an fp operation to int or
7836 vice versa, and we would not be converting a single-word
7837 operation into a multi-word operation. The latter test is not
7838 required, but it prevents generating unneeded multi-word operations.
7839 Some of the previous tests are redundant given the latter test, but
7840 are retained because they are required for correctness.
7841
7842 We produce the result slightly differently in this case. */
7843
7844 if (GET_MODE (SUBREG_REG (lhs)) != GET_MODE (SUBREG_REG (rhs))
7845 || SUBREG_BYTE (lhs) != SUBREG_BYTE (rhs)
7846 || ! subreg_lowpart_p (lhs)
7847 || (GET_MODE_CLASS (GET_MODE (lhs))
7848 != GET_MODE_CLASS (GET_MODE (SUBREG_REG (lhs))))
7849 || (GET_MODE_SIZE (GET_MODE (lhs))
7850 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))))
7851 || GET_MODE_SIZE (GET_MODE (SUBREG_REG (lhs))) > UNITS_PER_WORD)
7852 return x;
7853
7854 tem = gen_binary (code, GET_MODE (SUBREG_REG (lhs)),
7855 SUBREG_REG (lhs), SUBREG_REG (rhs));
7856 return gen_lowpart_for_combine (GET_MODE (x), tem);
7857
7858 default:
7859 return x;
7860 }
7861
7862 /* Set LHS and RHS to the inner operands (A and B in the example
7863 above) and set OTHER to the common operand (C in the example).
7864 These is only one way to do this unless the inner operation is
7865 commutative. */
7866 if (GET_RTX_CLASS (inner_code) == 'c'
7867 && rtx_equal_p (XEXP (lhs, 0), XEXP (rhs, 0)))
7868 other = XEXP (lhs, 0), lhs = XEXP (lhs, 1), rhs = XEXP (rhs, 1);
7869 else if (GET_RTX_CLASS (inner_code) == 'c'
7870 && rtx_equal_p (XEXP (lhs, 0), XEXP (rhs, 1)))
7871 other = XEXP (lhs, 0), lhs = XEXP (lhs, 1), rhs = XEXP (rhs, 0);
7872 else if (GET_RTX_CLASS (inner_code) == 'c'
7873 && rtx_equal_p (XEXP (lhs, 1), XEXP (rhs, 0)))
7874 other = XEXP (lhs, 1), lhs = XEXP (lhs, 0), rhs = XEXP (rhs, 1);
7875 else if (rtx_equal_p (XEXP (lhs, 1), XEXP (rhs, 1)))
7876 other = XEXP (lhs, 1), lhs = XEXP (lhs, 0), rhs = XEXP (rhs, 0);
7877 else
7878 return x;
7879
7880 /* Form the new inner operation, seeing if it simplifies first. */
7881 tem = gen_binary (code, GET_MODE (x), lhs, rhs);
7882
7883 /* There is one exception to the general way of distributing:
7884 (a | c) ^ (b | c) -> (a ^ b) & ~c */
7885 if (code == XOR && inner_code == IOR)
7886 {
7887 inner_code = AND;
7888 other = simplify_gen_unary (NOT, GET_MODE (x), other, GET_MODE (x));
7889 }
7890
7891 /* We may be able to continuing distributing the result, so call
7892 ourselves recursively on the inner operation before forming the
7893 outer operation, which we return. */
7894 return gen_binary (inner_code, GET_MODE (x),
7895 apply_distributive_law (tem), other);
7896 }
7897
7898 /* We have X, a logical `and' of VAROP with the constant CONSTOP, to be done
7899 in MODE.
7900
7901 Return an equivalent form, if different from X. Otherwise, return X. If
7902 X is zero, we are to always construct the equivalent form. */
7903
7904 static rtx
simplify_and_const_int(rtx x,enum machine_mode mode,rtx varop,unsigned HOST_WIDE_INT constop)7905 simplify_and_const_int (rtx x, enum machine_mode mode, rtx varop,
7906 unsigned HOST_WIDE_INT constop)
7907 {
7908 unsigned HOST_WIDE_INT nonzero;
7909 int i;
7910
7911 /* Simplify VAROP knowing that we will be only looking at some of the
7912 bits in it.
7913
7914 Note by passing in CONSTOP, we guarantee that the bits not set in
7915 CONSTOP are not significant and will never be examined. We must
7916 ensure that is the case by explicitly masking out those bits
7917 before returning. */
7918 varop = force_to_mode (varop, mode, constop, NULL_RTX, 0);
7919
7920 /* If VAROP is a CLOBBER, we will fail so return it. */
7921 if (GET_CODE (varop) == CLOBBER)
7922 return varop;
7923
7924 /* If VAROP is a CONST_INT, then we need to apply the mask in CONSTOP
7925 to VAROP and return the new constant. */
7926 if (GET_CODE (varop) == CONST_INT)
7927 return GEN_INT (trunc_int_for_mode (INTVAL (varop) & constop, mode));
7928
7929 /* See what bits may be nonzero in VAROP. Unlike the general case of
7930 a call to nonzero_bits, here we don't care about bits outside
7931 MODE. */
7932
7933 nonzero = nonzero_bits (varop, mode) & GET_MODE_MASK (mode);
7934
7935 /* Turn off all bits in the constant that are known to already be zero.
7936 Thus, if the AND isn't needed at all, we will have CONSTOP == NONZERO_BITS
7937 which is tested below. */
7938
7939 constop &= nonzero;
7940
7941 /* If we don't have any bits left, return zero. */
7942 if (constop == 0)
7943 return const0_rtx;
7944
7945 /* If VAROP is a NEG of something known to be zero or 1 and CONSTOP is
7946 a power of two, we can replace this with an ASHIFT. */
7947 if (GET_CODE (varop) == NEG && nonzero_bits (XEXP (varop, 0), mode) == 1
7948 && (i = exact_log2 (constop)) >= 0)
7949 return simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (varop, 0), i);
7950
7951 /* If VAROP is an IOR or XOR, apply the AND to both branches of the IOR
7952 or XOR, then try to apply the distributive law. This may eliminate
7953 operations if either branch can be simplified because of the AND.
7954 It may also make some cases more complex, but those cases probably
7955 won't match a pattern either with or without this. */
7956
7957 if (GET_CODE (varop) == IOR || GET_CODE (varop) == XOR)
7958 return
7959 gen_lowpart_for_combine
7960 (mode,
7961 apply_distributive_law
7962 (gen_binary (GET_CODE (varop), GET_MODE (varop),
7963 simplify_and_const_int (NULL_RTX, GET_MODE (varop),
7964 XEXP (varop, 0), constop),
7965 simplify_and_const_int (NULL_RTX, GET_MODE (varop),
7966 XEXP (varop, 1), constop))));
7967
7968 /* If VAROP is PLUS, and the constant is a mask of low bite, distribute
7969 the AND and see if one of the operands simplifies to zero. If so, we
7970 may eliminate it. */
7971
7972 if (GET_CODE (varop) == PLUS
7973 && exact_log2 (constop + 1) >= 0)
7974 {
7975 rtx o0, o1;
7976
7977 o0 = simplify_and_const_int (NULL_RTX, mode, XEXP (varop, 0), constop);
7978 o1 = simplify_and_const_int (NULL_RTX, mode, XEXP (varop, 1), constop);
7979 if (o0 == const0_rtx)
7980 return o1;
7981 if (o1 == const0_rtx)
7982 return o0;
7983 }
7984
7985 /* Get VAROP in MODE. Try to get a SUBREG if not. Don't make a new SUBREG
7986 if we already had one (just check for the simplest cases). */
7987 if (x && GET_CODE (XEXP (x, 0)) == SUBREG
7988 && GET_MODE (XEXP (x, 0)) == mode
7989 && SUBREG_REG (XEXP (x, 0)) == varop)
7990 varop = XEXP (x, 0);
7991 else
7992 varop = gen_lowpart_for_combine (mode, varop);
7993
7994 /* If we can't make the SUBREG, try to return what we were given. */
7995 if (GET_CODE (varop) == CLOBBER)
7996 return x ? x : varop;
7997
7998 /* If we are only masking insignificant bits, return VAROP. */
7999 if (constop == nonzero)
8000 x = varop;
8001 else
8002 {
8003 /* Otherwise, return an AND. */
8004 constop = trunc_int_for_mode (constop, mode);
8005 /* See how much, if any, of X we can use. */
8006 if (x == 0 || GET_CODE (x) != AND || GET_MODE (x) != mode)
8007 x = gen_binary (AND, mode, varop, GEN_INT (constop));
8008
8009 else
8010 {
8011 if (GET_CODE (XEXP (x, 1)) != CONST_INT
8012 || (unsigned HOST_WIDE_INT) INTVAL (XEXP (x, 1)) != constop)
8013 SUBST (XEXP (x, 1), GEN_INT (constop));
8014
8015 SUBST (XEXP (x, 0), varop);
8016 }
8017 }
8018
8019 return x;
8020 }
8021
8022 #define nonzero_bits_with_known(X, MODE) \
8023 cached_nonzero_bits (X, MODE, known_x, known_mode, known_ret)
8024
8025 /* The function cached_nonzero_bits is a wrapper around nonzero_bits1.
8026 It avoids exponential behavior in nonzero_bits1 when X has
8027 identical subexpressions on the first or the second level. */
8028
8029 static unsigned HOST_WIDE_INT
cached_nonzero_bits(rtx x,enum machine_mode mode,rtx known_x,enum machine_mode known_mode,unsigned HOST_WIDE_INT known_ret)8030 cached_nonzero_bits (rtx x, enum machine_mode mode, rtx known_x,
8031 enum machine_mode known_mode,
8032 unsigned HOST_WIDE_INT known_ret)
8033 {
8034 if (x == known_x && mode == known_mode)
8035 return known_ret;
8036
8037 /* Try to find identical subexpressions. If found call
8038 nonzero_bits1 on X with the subexpressions as KNOWN_X and the
8039 precomputed value for the subexpression as KNOWN_RET. */
8040
8041 if (GET_RTX_CLASS (GET_CODE (x)) == '2'
8042 || GET_RTX_CLASS (GET_CODE (x)) == 'c')
8043 {
8044 rtx x0 = XEXP (x, 0);
8045 rtx x1 = XEXP (x, 1);
8046
8047 /* Check the first level. */
8048 if (x0 == x1)
8049 return nonzero_bits1 (x, mode, x0, mode,
8050 nonzero_bits_with_known (x0, mode));
8051
8052 /* Check the second level. */
8053 if ((GET_RTX_CLASS (GET_CODE (x0)) == '2'
8054 || GET_RTX_CLASS (GET_CODE (x0)) == 'c')
8055 && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1)))
8056 return nonzero_bits1 (x, mode, x1, mode,
8057 nonzero_bits_with_known (x1, mode));
8058
8059 if ((GET_RTX_CLASS (GET_CODE (x1)) == '2'
8060 || GET_RTX_CLASS (GET_CODE (x1)) == 'c')
8061 && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1)))
8062 return nonzero_bits1 (x, mode, x0, mode,
8063 nonzero_bits_with_known (x0, mode));
8064 }
8065
8066 return nonzero_bits1 (x, mode, known_x, known_mode, known_ret);
8067 }
8068
8069 /* We let num_sign_bit_copies recur into nonzero_bits as that is useful.
8070 We don't let nonzero_bits recur into num_sign_bit_copies, because that
8071 is less useful. We can't allow both, because that results in exponential
8072 run time recursion. There is a nullstone testcase that triggered
8073 this. This macro avoids accidental uses of num_sign_bit_copies. */
8074 #define cached_num_sign_bit_copies()
8075
8076 /* Given an expression, X, compute which bits in X can be nonzero.
8077 We don't care about bits outside of those defined in MODE.
8078
8079 For most X this is simply GET_MODE_MASK (GET_MODE (MODE)), but if X is
8080 a shift, AND, or zero_extract, we can do better. */
8081
8082 static unsigned HOST_WIDE_INT
nonzero_bits1(rtx x,enum machine_mode mode,rtx known_x,enum machine_mode known_mode,unsigned HOST_WIDE_INT known_ret)8083 nonzero_bits1 (rtx x, enum machine_mode mode, rtx known_x,
8084 enum machine_mode known_mode,
8085 unsigned HOST_WIDE_INT known_ret)
8086 {
8087 unsigned HOST_WIDE_INT nonzero = GET_MODE_MASK (mode);
8088 unsigned HOST_WIDE_INT inner_nz;
8089 enum rtx_code code;
8090 unsigned int mode_width = GET_MODE_BITSIZE (mode);
8091 rtx tem;
8092
8093 /* For floating-point values, assume all bits are needed. */
8094 if (FLOAT_MODE_P (GET_MODE (x)) || FLOAT_MODE_P (mode))
8095 return nonzero;
8096
8097 /* If X is wider than MODE, use its mode instead. */
8098 if (GET_MODE_BITSIZE (GET_MODE (x)) > mode_width)
8099 {
8100 mode = GET_MODE (x);
8101 nonzero = GET_MODE_MASK (mode);
8102 mode_width = GET_MODE_BITSIZE (mode);
8103 }
8104
8105 if (mode_width > HOST_BITS_PER_WIDE_INT)
8106 /* Our only callers in this case look for single bit values. So
8107 just return the mode mask. Those tests will then be false. */
8108 return nonzero;
8109
8110 #ifndef WORD_REGISTER_OPERATIONS
8111 /* If MODE is wider than X, but both are a single word for both the host
8112 and target machines, we can compute this from which bits of the
8113 object might be nonzero in its own mode, taking into account the fact
8114 that on many CISC machines, accessing an object in a wider mode
8115 causes the high-order bits to become undefined. So they are
8116 not known to be zero. */
8117
8118 if (GET_MODE (x) != VOIDmode && GET_MODE (x) != mode
8119 && GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD
8120 && GET_MODE_BITSIZE (GET_MODE (x)) <= HOST_BITS_PER_WIDE_INT
8121 && GET_MODE_BITSIZE (mode) > GET_MODE_BITSIZE (GET_MODE (x)))
8122 {
8123 nonzero &= nonzero_bits_with_known (x, GET_MODE (x));
8124 nonzero |= GET_MODE_MASK (mode) & ~GET_MODE_MASK (GET_MODE (x));
8125 return nonzero;
8126 }
8127 #endif
8128
8129 code = GET_CODE (x);
8130 switch (code)
8131 {
8132 case REG:
8133 #if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend)
8134 /* If pointers extend unsigned and this is a pointer in Pmode, say that
8135 all the bits above ptr_mode are known to be zero. */
8136 if (POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode
8137 && REG_POINTER (x))
8138 nonzero &= GET_MODE_MASK (ptr_mode);
8139 #endif
8140
8141 /* Include declared information about alignment of pointers. */
8142 /* ??? We don't properly preserve REG_POINTER changes across
8143 pointer-to-integer casts, so we can't trust it except for
8144 things that we know must be pointers. See execute/960116-1.c. */
8145 if ((x == stack_pointer_rtx
8146 || x == frame_pointer_rtx
8147 || x == arg_pointer_rtx)
8148 && REGNO_POINTER_ALIGN (REGNO (x)))
8149 {
8150 unsigned HOST_WIDE_INT alignment
8151 = REGNO_POINTER_ALIGN (REGNO (x)) / BITS_PER_UNIT;
8152
8153 #ifdef PUSH_ROUNDING
8154 /* If PUSH_ROUNDING is defined, it is possible for the
8155 stack to be momentarily aligned only to that amount,
8156 so we pick the least alignment. */
8157 if (x == stack_pointer_rtx && PUSH_ARGS)
8158 alignment = MIN ((unsigned HOST_WIDE_INT) PUSH_ROUNDING (1),
8159 alignment);
8160 #endif
8161
8162 nonzero &= ~(alignment - 1);
8163 }
8164
8165 /* If X is a register whose nonzero bits value is current, use it.
8166 Otherwise, if X is a register whose value we can find, use that
8167 value. Otherwise, use the previously-computed global nonzero bits
8168 for this register. */
8169
8170 if (reg_last_set_value[REGNO (x)] != 0
8171 && (reg_last_set_mode[REGNO (x)] == mode
8172 || (GET_MODE_CLASS (reg_last_set_mode[REGNO (x)]) == MODE_INT
8173 && GET_MODE_CLASS (mode) == MODE_INT))
8174 && (reg_last_set_label[REGNO (x)] == label_tick
8175 || (REGNO (x) >= FIRST_PSEUDO_REGISTER
8176 && REG_N_SETS (REGNO (x)) == 1
8177 && ! REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start,
8178 REGNO (x))))
8179 && INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid)
8180 return reg_last_set_nonzero_bits[REGNO (x)] & nonzero;
8181
8182 tem = get_last_value (x);
8183
8184 if (tem)
8185 {
8186 #ifdef SHORT_IMMEDIATES_SIGN_EXTEND
8187 /* If X is narrower than MODE and TEM is a non-negative
8188 constant that would appear negative in the mode of X,
8189 sign-extend it for use in reg_nonzero_bits because some
8190 machines (maybe most) will actually do the sign-extension
8191 and this is the conservative approach.
8192
8193 ??? For 2.5, try to tighten up the MD files in this regard
8194 instead of this kludge. */
8195
8196 if (GET_MODE_BITSIZE (GET_MODE (x)) < mode_width
8197 && GET_CODE (tem) == CONST_INT
8198 && INTVAL (tem) > 0
8199 && 0 != (INTVAL (tem)
8200 & ((HOST_WIDE_INT) 1
8201 << (GET_MODE_BITSIZE (GET_MODE (x)) - 1))))
8202 tem = GEN_INT (INTVAL (tem)
8203 | ((HOST_WIDE_INT) (-1)
8204 << GET_MODE_BITSIZE (GET_MODE (x))));
8205 #endif
8206 return nonzero_bits_with_known (tem, mode) & nonzero;
8207 }
8208 else if (nonzero_sign_valid && reg_nonzero_bits[REGNO (x)])
8209 {
8210 unsigned HOST_WIDE_INT mask = reg_nonzero_bits[REGNO (x)];
8211
8212 if (GET_MODE_BITSIZE (GET_MODE (x)) < mode_width)
8213 /* We don't know anything about the upper bits. */
8214 mask |= GET_MODE_MASK (mode) ^ GET_MODE_MASK (GET_MODE (x));
8215 return nonzero & mask;
8216 }
8217 else
8218 return nonzero;
8219
8220 case CONST_INT:
8221 #ifdef SHORT_IMMEDIATES_SIGN_EXTEND
8222 /* If X is negative in MODE, sign-extend the value. */
8223 if (INTVAL (x) > 0 && mode_width < BITS_PER_WORD
8224 && 0 != (INTVAL (x) & ((HOST_WIDE_INT) 1 << (mode_width - 1))))
8225 return (INTVAL (x) | ((HOST_WIDE_INT) (-1) << mode_width));
8226 #endif
8227
8228 return INTVAL (x);
8229
8230 case MEM:
8231 #ifdef LOAD_EXTEND_OP
8232 /* In many, if not most, RISC machines, reading a byte from memory
8233 zeros the rest of the register. Noticing that fact saves a lot
8234 of extra zero-extends. */
8235 if (LOAD_EXTEND_OP (GET_MODE (x)) == ZERO_EXTEND)
8236 nonzero &= GET_MODE_MASK (GET_MODE (x));
8237 #endif
8238 break;
8239
8240 case EQ: case NE:
8241 case UNEQ: case LTGT:
8242 case GT: case GTU: case UNGT:
8243 case LT: case LTU: case UNLT:
8244 case GE: case GEU: case UNGE:
8245 case LE: case LEU: case UNLE:
8246 case UNORDERED: case ORDERED:
8247
8248 /* If this produces an integer result, we know which bits are set.
8249 Code here used to clear bits outside the mode of X, but that is
8250 now done above. */
8251
8252 if (GET_MODE_CLASS (mode) == MODE_INT
8253 && mode_width <= HOST_BITS_PER_WIDE_INT)
8254 nonzero = STORE_FLAG_VALUE;
8255 break;
8256
8257 case NEG:
8258 #if 0
8259 /* Disabled to avoid exponential mutual recursion between nonzero_bits
8260 and num_sign_bit_copies. */
8261 if (num_sign_bit_copies (XEXP (x, 0), GET_MODE (x))
8262 == GET_MODE_BITSIZE (GET_MODE (x)))
8263 nonzero = 1;
8264 #endif
8265
8266 if (GET_MODE_SIZE (GET_MODE (x)) < mode_width)
8267 nonzero |= (GET_MODE_MASK (mode) & ~GET_MODE_MASK (GET_MODE (x)));
8268 break;
8269
8270 case ABS:
8271 #if 0
8272 /* Disabled to avoid exponential mutual recursion between nonzero_bits
8273 and num_sign_bit_copies. */
8274 if (num_sign_bit_copies (XEXP (x, 0), GET_MODE (x))
8275 == GET_MODE_BITSIZE (GET_MODE (x)))
8276 nonzero = 1;
8277 #endif
8278 break;
8279
8280 case TRUNCATE:
8281 nonzero &= (nonzero_bits_with_known (XEXP (x, 0), mode)
8282 & GET_MODE_MASK (mode));
8283 break;
8284
8285 case ZERO_EXTEND:
8286 nonzero &= nonzero_bits_with_known (XEXP (x, 0), mode);
8287 if (GET_MODE (XEXP (x, 0)) != VOIDmode)
8288 nonzero &= GET_MODE_MASK (GET_MODE (XEXP (x, 0)));
8289 break;
8290
8291 case SIGN_EXTEND:
8292 /* If the sign bit is known clear, this is the same as ZERO_EXTEND.
8293 Otherwise, show all the bits in the outer mode but not the inner
8294 may be nonzero. */
8295 inner_nz = nonzero_bits_with_known (XEXP (x, 0), mode);
8296 if (GET_MODE (XEXP (x, 0)) != VOIDmode)
8297 {
8298 inner_nz &= GET_MODE_MASK (GET_MODE (XEXP (x, 0)));
8299 if (inner_nz
8300 & (((HOST_WIDE_INT) 1
8301 << (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0))) - 1))))
8302 inner_nz |= (GET_MODE_MASK (mode)
8303 & ~GET_MODE_MASK (GET_MODE (XEXP (x, 0))));
8304 }
8305
8306 nonzero &= inner_nz;
8307 break;
8308
8309 case AND:
8310 nonzero &= (nonzero_bits_with_known (XEXP (x, 0), mode)
8311 & nonzero_bits_with_known (XEXP (x, 1), mode));
8312 break;
8313
8314 case XOR: case IOR:
8315 case UMIN: case UMAX: case SMIN: case SMAX:
8316 {
8317 unsigned HOST_WIDE_INT nonzero0 =
8318 nonzero_bits_with_known (XEXP (x, 0), mode);
8319
8320 /* Don't call nonzero_bits for the second time if it cannot change
8321 anything. */
8322 if ((nonzero & nonzero0) != nonzero)
8323 nonzero &= (nonzero0
8324 | nonzero_bits_with_known (XEXP (x, 1), mode));
8325 }
8326 break;
8327
8328 case PLUS: case MINUS:
8329 case MULT:
8330 case DIV: case UDIV:
8331 case MOD: case UMOD:
8332 /* We can apply the rules of arithmetic to compute the number of
8333 high- and low-order zero bits of these operations. We start by
8334 computing the width (position of the highest-order nonzero bit)
8335 and the number of low-order zero bits for each value. */
8336 {
8337 unsigned HOST_WIDE_INT nz0 =
8338 nonzero_bits_with_known (XEXP (x, 0), mode);
8339 unsigned HOST_WIDE_INT nz1 =
8340 nonzero_bits_with_known (XEXP (x, 1), mode);
8341 int sign_index = GET_MODE_BITSIZE (GET_MODE (x)) - 1;
8342 int width0 = floor_log2 (nz0) + 1;
8343 int width1 = floor_log2 (nz1) + 1;
8344 int low0 = floor_log2 (nz0 & -nz0);
8345 int low1 = floor_log2 (nz1 & -nz1);
8346 HOST_WIDE_INT op0_maybe_minusp
8347 = (nz0 & ((HOST_WIDE_INT) 1 << sign_index));
8348 HOST_WIDE_INT op1_maybe_minusp
8349 = (nz1 & ((HOST_WIDE_INT) 1 << sign_index));
8350 unsigned int result_width = mode_width;
8351 int result_low = 0;
8352
8353 switch (code)
8354 {
8355 case PLUS:
8356 result_width = MAX (width0, width1) + 1;
8357 result_low = MIN (low0, low1);
8358 break;
8359 case MINUS:
8360 result_low = MIN (low0, low1);
8361 break;
8362 case MULT:
8363 result_width = width0 + width1;
8364 result_low = low0 + low1;
8365 break;
8366 case DIV:
8367 if (width1 == 0)
8368 break;
8369 if (! op0_maybe_minusp && ! op1_maybe_minusp)
8370 result_width = width0;
8371 break;
8372 case UDIV:
8373 if (width1 == 0)
8374 break;
8375 result_width = width0;
8376 break;
8377 case MOD:
8378 if (width1 == 0)
8379 break;
8380 if (! op0_maybe_minusp && ! op1_maybe_minusp)
8381 result_width = MIN (width0, width1);
8382 result_low = MIN (low0, low1);
8383 break;
8384 case UMOD:
8385 if (width1 == 0)
8386 break;
8387 result_width = MIN (width0, width1);
8388 result_low = MIN (low0, low1);
8389 break;
8390 default:
8391 abort ();
8392 }
8393
8394 if (result_width < mode_width)
8395 nonzero &= ((HOST_WIDE_INT) 1 << result_width) - 1;
8396
8397 if (result_low > 0)
8398 nonzero &= ~(((HOST_WIDE_INT) 1 << result_low) - 1);
8399
8400 #ifdef POINTERS_EXTEND_UNSIGNED
8401 /* If pointers extend unsigned and this is an addition or subtraction
8402 to a pointer in Pmode, all the bits above ptr_mode are known to be
8403 zero. */
8404 if (POINTERS_EXTEND_UNSIGNED > 0 && GET_MODE (x) == Pmode
8405 && (code == PLUS || code == MINUS)
8406 && GET_CODE (XEXP (x, 0)) == REG && REG_POINTER (XEXP (x, 0)))
8407 nonzero &= GET_MODE_MASK (ptr_mode);
8408 #endif
8409 }
8410 break;
8411
8412 case ZERO_EXTRACT:
8413 if (GET_CODE (XEXP (x, 1)) == CONST_INT
8414 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT)
8415 nonzero &= ((HOST_WIDE_INT) 1 << INTVAL (XEXP (x, 1))) - 1;
8416 break;
8417
8418 case SUBREG:
8419 /* If this is a SUBREG formed for a promoted variable that has
8420 been zero-extended, we know that at least the high-order bits
8421 are zero, though others might be too. */
8422
8423 if (SUBREG_PROMOTED_VAR_P (x) && SUBREG_PROMOTED_UNSIGNED_P (x) > 0)
8424 nonzero = (GET_MODE_MASK (GET_MODE (x))
8425 & nonzero_bits_with_known (SUBREG_REG (x), GET_MODE (x)));
8426
8427 /* If the inner mode is a single word for both the host and target
8428 machines, we can compute this from which bits of the inner
8429 object might be nonzero. */
8430 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) <= BITS_PER_WORD
8431 && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))
8432 <= HOST_BITS_PER_WIDE_INT))
8433 {
8434 nonzero &= nonzero_bits_with_known (SUBREG_REG (x), mode);
8435
8436 #if defined (WORD_REGISTER_OPERATIONS) && defined (LOAD_EXTEND_OP)
8437 /* If this is a typical RISC machine, we only have to worry
8438 about the way loads are extended. */
8439 if ((LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) == SIGN_EXTEND
8440 ? (((nonzero
8441 & (((unsigned HOST_WIDE_INT) 1
8442 << (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) - 1))))
8443 != 0))
8444 : LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) != ZERO_EXTEND)
8445 || GET_CODE (SUBREG_REG (x)) != MEM)
8446 #endif
8447 {
8448 /* On many CISC machines, accessing an object in a wider mode
8449 causes the high-order bits to become undefined. So they are
8450 not known to be zero. */
8451 if (GET_MODE_SIZE (GET_MODE (x))
8452 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
8453 nonzero |= (GET_MODE_MASK (GET_MODE (x))
8454 & ~GET_MODE_MASK (GET_MODE (SUBREG_REG (x))));
8455 }
8456 }
8457 break;
8458
8459 case ASHIFTRT:
8460 case LSHIFTRT:
8461 case ASHIFT:
8462 case ROTATE:
8463 /* The nonzero bits are in two classes: any bits within MODE
8464 that aren't in GET_MODE (x) are always significant. The rest of the
8465 nonzero bits are those that are significant in the operand of
8466 the shift when shifted the appropriate number of bits. This
8467 shows that high-order bits are cleared by the right shift and
8468 low-order bits by left shifts. */
8469 if (GET_CODE (XEXP (x, 1)) == CONST_INT
8470 && INTVAL (XEXP (x, 1)) >= 0
8471 && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT)
8472 {
8473 enum machine_mode inner_mode = GET_MODE (x);
8474 unsigned int width = GET_MODE_BITSIZE (inner_mode);
8475 int count = INTVAL (XEXP (x, 1));
8476 unsigned HOST_WIDE_INT mode_mask = GET_MODE_MASK (inner_mode);
8477 unsigned HOST_WIDE_INT op_nonzero =
8478 nonzero_bits_with_known (XEXP (x, 0), mode);
8479 unsigned HOST_WIDE_INT inner = op_nonzero & mode_mask;
8480 unsigned HOST_WIDE_INT outer = 0;
8481
8482 if (mode_width > width)
8483 outer = (op_nonzero & nonzero & ~mode_mask);
8484
8485 if (code == LSHIFTRT)
8486 inner >>= count;
8487 else if (code == ASHIFTRT)
8488 {
8489 inner >>= count;
8490
8491 /* If the sign bit may have been nonzero before the shift, we
8492 need to mark all the places it could have been copied to
8493 by the shift as possibly nonzero. */
8494 if (inner & ((HOST_WIDE_INT) 1 << (width - 1 - count)))
8495 inner |= (((HOST_WIDE_INT) 1 << count) - 1) << (width - count);
8496 }
8497 else if (code == ASHIFT)
8498 inner <<= count;
8499 else
8500 inner = ((inner << (count % width)
8501 | (inner >> (width - (count % width)))) & mode_mask);
8502
8503 nonzero &= (outer | inner);
8504 }
8505 break;
8506
8507 case FFS:
8508 case POPCOUNT:
8509 /* This is at most the number of bits in the mode. */
8510 nonzero = ((HOST_WIDE_INT) 2 << (floor_log2 (mode_width))) - 1;
8511 break;
8512
8513 case CLZ:
8514 /* If CLZ has a known value at zero, then the nonzero bits are
8515 that value, plus the number of bits in the mode minus one. */
8516 if (CLZ_DEFINED_VALUE_AT_ZERO (mode, nonzero))
8517 nonzero |= ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width))) - 1;
8518 else
8519 nonzero = -1;
8520 break;
8521
8522 case CTZ:
8523 /* If CTZ has a known value at zero, then the nonzero bits are
8524 that value, plus the number of bits in the mode minus one. */
8525 if (CTZ_DEFINED_VALUE_AT_ZERO (mode, nonzero))
8526 nonzero |= ((HOST_WIDE_INT) 1 << (floor_log2 (mode_width))) - 1;
8527 else
8528 nonzero = -1;
8529 break;
8530
8531 case PARITY:
8532 nonzero = 1;
8533 break;
8534
8535 case IF_THEN_ELSE:
8536 nonzero &= (nonzero_bits_with_known (XEXP (x, 1), mode)
8537 | nonzero_bits_with_known (XEXP (x, 2), mode));
8538 break;
8539
8540 default:
8541 break;
8542 }
8543
8544 return nonzero;
8545 }
8546
8547 /* See the macro definition above. */
8548 #undef cached_num_sign_bit_copies
8549
8550 #define num_sign_bit_copies_with_known(X, M) \
8551 cached_num_sign_bit_copies (X, M, known_x, known_mode, known_ret)
8552
8553 /* The function cached_num_sign_bit_copies is a wrapper around
8554 num_sign_bit_copies1. It avoids exponential behavior in
8555 num_sign_bit_copies1 when X has identical subexpressions on the
8556 first or the second level. */
8557
8558 static unsigned int
cached_num_sign_bit_copies(rtx x,enum machine_mode mode,rtx known_x,enum machine_mode known_mode,unsigned int known_ret)8559 cached_num_sign_bit_copies (rtx x, enum machine_mode mode, rtx known_x,
8560 enum machine_mode known_mode,
8561 unsigned int known_ret)
8562 {
8563 if (x == known_x && mode == known_mode)
8564 return known_ret;
8565
8566 /* Try to find identical subexpressions. If found call
8567 num_sign_bit_copies1 on X with the subexpressions as KNOWN_X and
8568 the precomputed value for the subexpression as KNOWN_RET. */
8569
8570 if (GET_RTX_CLASS (GET_CODE (x)) == '2'
8571 || GET_RTX_CLASS (GET_CODE (x)) == 'c')
8572 {
8573 rtx x0 = XEXP (x, 0);
8574 rtx x1 = XEXP (x, 1);
8575
8576 /* Check the first level. */
8577 if (x0 == x1)
8578 return
8579 num_sign_bit_copies1 (x, mode, x0, mode,
8580 num_sign_bit_copies_with_known (x0, mode));
8581
8582 /* Check the second level. */
8583 if ((GET_RTX_CLASS (GET_CODE (x0)) == '2'
8584 || GET_RTX_CLASS (GET_CODE (x0)) == 'c')
8585 && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1)))
8586 return
8587 num_sign_bit_copies1 (x, mode, x1, mode,
8588 num_sign_bit_copies_with_known (x1, mode));
8589
8590 if ((GET_RTX_CLASS (GET_CODE (x1)) == '2'
8591 || GET_RTX_CLASS (GET_CODE (x1)) == 'c')
8592 && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1)))
8593 return
8594 num_sign_bit_copies1 (x, mode, x0, mode,
8595 num_sign_bit_copies_with_known (x0, mode));
8596 }
8597
8598 return num_sign_bit_copies1 (x, mode, known_x, known_mode, known_ret);
8599 }
8600
8601 /* Return the number of bits at the high-order end of X that are known to
8602 be equal to the sign bit. X will be used in mode MODE; if MODE is
8603 VOIDmode, X will be used in its own mode. The returned value will always
8604 be between 1 and the number of bits in MODE. */
8605
8606 static unsigned int
num_sign_bit_copies1(rtx x,enum machine_mode mode,rtx known_x,enum machine_mode known_mode,unsigned int known_ret)8607 num_sign_bit_copies1 (rtx x, enum machine_mode mode, rtx known_x,
8608 enum machine_mode known_mode,
8609 unsigned int known_ret)
8610 {
8611 enum rtx_code code = GET_CODE (x);
8612 unsigned int bitwidth;
8613 int num0, num1, result;
8614 unsigned HOST_WIDE_INT nonzero;
8615 rtx tem;
8616
8617 /* If we weren't given a mode, use the mode of X. If the mode is still
8618 VOIDmode, we don't know anything. Likewise if one of the modes is
8619 floating-point. */
8620
8621 if (mode == VOIDmode)
8622 mode = GET_MODE (x);
8623
8624 if (mode == VOIDmode || FLOAT_MODE_P (mode) || FLOAT_MODE_P (GET_MODE (x)))
8625 return 1;
8626
8627 bitwidth = GET_MODE_BITSIZE (mode);
8628
8629 /* For a smaller object, just ignore the high bits. */
8630 if (bitwidth < GET_MODE_BITSIZE (GET_MODE (x)))
8631 {
8632 num0 = num_sign_bit_copies_with_known (x, GET_MODE (x));
8633 return MAX (1,
8634 num0 - (int) (GET_MODE_BITSIZE (GET_MODE (x)) - bitwidth));
8635 }
8636
8637 if (GET_MODE (x) != VOIDmode && bitwidth > GET_MODE_BITSIZE (GET_MODE (x)))
8638 {
8639 #ifndef WORD_REGISTER_OPERATIONS
8640 /* If this machine does not do all register operations on the entire
8641 register and MODE is wider than the mode of X, we can say nothing
8642 at all about the high-order bits. */
8643 return 1;
8644 #else
8645 /* Likewise on machines that do, if the mode of the object is smaller
8646 than a word and loads of that size don't sign extend, we can say
8647 nothing about the high order bits. */
8648 if (GET_MODE_BITSIZE (GET_MODE (x)) < BITS_PER_WORD
8649 #ifdef LOAD_EXTEND_OP
8650 && LOAD_EXTEND_OP (GET_MODE (x)) != SIGN_EXTEND
8651 #endif
8652 )
8653 return 1;
8654 #endif
8655 }
8656
8657 switch (code)
8658 {
8659 case REG:
8660
8661 #if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend)
8662 /* If pointers extend signed and this is a pointer in Pmode, say that
8663 all the bits above ptr_mode are known to be sign bit copies. */
8664 if (! POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode && mode == Pmode
8665 && REG_POINTER (x))
8666 return GET_MODE_BITSIZE (Pmode) - GET_MODE_BITSIZE (ptr_mode) + 1;
8667 #endif
8668
8669 if (reg_last_set_value[REGNO (x)] != 0
8670 && reg_last_set_mode[REGNO (x)] == mode
8671 && (reg_last_set_label[REGNO (x)] == label_tick
8672 || (REGNO (x) >= FIRST_PSEUDO_REGISTER
8673 && REG_N_SETS (REGNO (x)) == 1
8674 && ! REGNO_REG_SET_P (ENTRY_BLOCK_PTR->next_bb->global_live_at_start,
8675 REGNO (x))))
8676 && INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid)
8677 return reg_last_set_sign_bit_copies[REGNO (x)];
8678
8679 tem = get_last_value (x);
8680 if (tem != 0)
8681 return num_sign_bit_copies_with_known (tem, mode);
8682
8683 if (nonzero_sign_valid && reg_sign_bit_copies[REGNO (x)] != 0
8684 && GET_MODE_BITSIZE (GET_MODE (x)) == bitwidth)
8685 return reg_sign_bit_copies[REGNO (x)];
8686 break;
8687
8688 case MEM:
8689 #ifdef LOAD_EXTEND_OP
8690 /* Some RISC machines sign-extend all loads of smaller than a word. */
8691 if (LOAD_EXTEND_OP (GET_MODE (x)) == SIGN_EXTEND)
8692 return MAX (1, ((int) bitwidth
8693 - (int) GET_MODE_BITSIZE (GET_MODE (x)) + 1));
8694 #endif
8695 break;
8696
8697 case CONST_INT:
8698 /* If the constant is negative, take its 1's complement and remask.
8699 Then see how many zero bits we have. */
8700 nonzero = INTVAL (x) & GET_MODE_MASK (mode);
8701 if (bitwidth <= HOST_BITS_PER_WIDE_INT
8702 && (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
8703 nonzero = (~nonzero) & GET_MODE_MASK (mode);
8704
8705 return (nonzero == 0 ? bitwidth : bitwidth - floor_log2 (nonzero) - 1);
8706
8707 case SUBREG:
8708 /* If this is a SUBREG for a promoted object that is sign-extended
8709 and we are looking at it in a wider mode, we know that at least the
8710 high-order bits are known to be sign bit copies. */
8711
8712 if (SUBREG_PROMOTED_VAR_P (x) && ! SUBREG_PROMOTED_UNSIGNED_P (x))
8713 {
8714 num0 = num_sign_bit_copies_with_known (SUBREG_REG (x), mode);
8715 return MAX ((int) bitwidth
8716 - (int) GET_MODE_BITSIZE (GET_MODE (x)) + 1,
8717 num0);
8718 }
8719
8720 /* For a smaller object, just ignore the high bits. */
8721 if (bitwidth <= GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))))
8722 {
8723 num0 = num_sign_bit_copies_with_known (SUBREG_REG (x), VOIDmode);
8724 return MAX (1, (num0
8725 - (int) (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))
8726 - bitwidth)));
8727 }
8728
8729 #ifdef WORD_REGISTER_OPERATIONS
8730 #ifdef LOAD_EXTEND_OP
8731 /* For paradoxical SUBREGs on machines where all register operations
8732 affect the entire register, just look inside. Note that we are
8733 passing MODE to the recursive call, so the number of sign bit copies
8734 will remain relative to that mode, not the inner mode. */
8735
8736 /* This works only if loads sign extend. Otherwise, if we get a
8737 reload for the inner part, it may be loaded from the stack, and
8738 then we lose all sign bit copies that existed before the store
8739 to the stack. */
8740
8741 if ((GET_MODE_SIZE (GET_MODE (x))
8742 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
8743 && LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) == SIGN_EXTEND
8744 && GET_CODE (SUBREG_REG (x)) == MEM)
8745 return num_sign_bit_copies_with_known (SUBREG_REG (x), mode);
8746 #endif
8747 #endif
8748 break;
8749
8750 case SIGN_EXTRACT:
8751 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
8752 return MAX (1, (int) bitwidth - INTVAL (XEXP (x, 1)));
8753 break;
8754
8755 case SIGN_EXTEND:
8756 return (bitwidth - GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
8757 + num_sign_bit_copies_with_known (XEXP (x, 0), VOIDmode));
8758
8759 case TRUNCATE:
8760 /* For a smaller object, just ignore the high bits. */
8761 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), VOIDmode);
8762 return MAX (1, (num0 - (int) (GET_MODE_BITSIZE (GET_MODE (XEXP (x, 0)))
8763 - bitwidth)));
8764
8765 case NOT:
8766 return num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8767
8768 case ROTATE: case ROTATERT:
8769 /* If we are rotating left by a number of bits less than the number
8770 of sign bit copies, we can just subtract that amount from the
8771 number. */
8772 if (GET_CODE (XEXP (x, 1)) == CONST_INT
8773 && INTVAL (XEXP (x, 1)) >= 0
8774 && INTVAL (XEXP (x, 1)) < (int) bitwidth)
8775 {
8776 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8777 return MAX (1, num0 - (code == ROTATE ? INTVAL (XEXP (x, 1))
8778 : (int) bitwidth - INTVAL (XEXP (x, 1))));
8779 }
8780 break;
8781
8782 case NEG:
8783 /* In general, this subtracts one sign bit copy. But if the value
8784 is known to be positive, the number of sign bit copies is the
8785 same as that of the input. Finally, if the input has just one bit
8786 that might be nonzero, all the bits are copies of the sign bit. */
8787 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8788 if (bitwidth > HOST_BITS_PER_WIDE_INT)
8789 return num0 > 1 ? num0 - 1 : 1;
8790
8791 nonzero = nonzero_bits (XEXP (x, 0), mode);
8792 if (nonzero == 1)
8793 return bitwidth;
8794
8795 if (num0 > 1
8796 && (((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero))
8797 num0--;
8798
8799 return num0;
8800
8801 case IOR: case AND: case XOR:
8802 case SMIN: case SMAX: case UMIN: case UMAX:
8803 /* Logical operations will preserve the number of sign-bit copies.
8804 MIN and MAX operations always return one of the operands. */
8805 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8806 num1 = num_sign_bit_copies_with_known (XEXP (x, 1), mode);
8807 return MIN (num0, num1);
8808
8809 case PLUS: case MINUS:
8810 /* For addition and subtraction, we can have a 1-bit carry. However,
8811 if we are subtracting 1 from a positive number, there will not
8812 be such a carry. Furthermore, if the positive number is known to
8813 be 0 or 1, we know the result is either -1 or 0. */
8814
8815 if (code == PLUS && XEXP (x, 1) == constm1_rtx
8816 && bitwidth <= HOST_BITS_PER_WIDE_INT)
8817 {
8818 nonzero = nonzero_bits (XEXP (x, 0), mode);
8819 if ((((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero) == 0)
8820 return (nonzero == 1 || nonzero == 0 ? bitwidth
8821 : bitwidth - floor_log2 (nonzero) - 1);
8822 }
8823
8824 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8825 num1 = num_sign_bit_copies_with_known (XEXP (x, 1), mode);
8826 result = MAX (1, MIN (num0, num1) - 1);
8827
8828 #ifdef POINTERS_EXTEND_UNSIGNED
8829 /* If pointers extend signed and this is an addition or subtraction
8830 to a pointer in Pmode, all the bits above ptr_mode are known to be
8831 sign bit copies. */
8832 if (! POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode
8833 && (code == PLUS || code == MINUS)
8834 && GET_CODE (XEXP (x, 0)) == REG && REG_POINTER (XEXP (x, 0)))
8835 result = MAX ((int) (GET_MODE_BITSIZE (Pmode)
8836 - GET_MODE_BITSIZE (ptr_mode) + 1),
8837 result);
8838 #endif
8839 return result;
8840
8841 case MULT:
8842 /* The number of bits of the product is the sum of the number of
8843 bits of both terms. However, unless one of the terms if known
8844 to be positive, we must allow for an additional bit since negating
8845 a negative number can remove one sign bit copy. */
8846
8847 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8848 num1 = num_sign_bit_copies_with_known (XEXP (x, 1), mode);
8849
8850 result = bitwidth - (bitwidth - num0) - (bitwidth - num1);
8851 if (result > 0
8852 && (bitwidth > HOST_BITS_PER_WIDE_INT
8853 || (((nonzero_bits (XEXP (x, 0), mode)
8854 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
8855 && ((nonzero_bits (XEXP (x, 1), mode)
8856 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))))
8857 result--;
8858
8859 return MAX (1, result);
8860
8861 case UDIV:
8862 /* The result must be <= the first operand. If the first operand
8863 has the high bit set, we know nothing about the number of sign
8864 bit copies. */
8865 if (bitwidth > HOST_BITS_PER_WIDE_INT)
8866 return 1;
8867 else if ((nonzero_bits (XEXP (x, 0), mode)
8868 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
8869 return 1;
8870 else
8871 return num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8872
8873 case UMOD:
8874 /* The result must be <= the second operand. */
8875 return num_sign_bit_copies_with_known (XEXP (x, 1), mode);
8876
8877 case DIV:
8878 /* Similar to unsigned division, except that we have to worry about
8879 the case where the divisor is negative, in which case we have
8880 to add 1. */
8881 result = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8882 if (result > 1
8883 && (bitwidth > HOST_BITS_PER_WIDE_INT
8884 || (nonzero_bits (XEXP (x, 1), mode)
8885 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
8886 result--;
8887
8888 return result;
8889
8890 case MOD:
8891 result = num_sign_bit_copies_with_known (XEXP (x, 1), mode);
8892 if (result > 1
8893 && (bitwidth > HOST_BITS_PER_WIDE_INT
8894 || (nonzero_bits (XEXP (x, 1), mode)
8895 & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
8896 result--;
8897
8898 return result;
8899
8900 case ASHIFTRT:
8901 /* Shifts by a constant add to the number of bits equal to the
8902 sign bit. */
8903 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8904 if (GET_CODE (XEXP (x, 1)) == CONST_INT
8905 && INTVAL (XEXP (x, 1)) > 0)
8906 num0 = MIN ((int) bitwidth, num0 + INTVAL (XEXP (x, 1)));
8907
8908 return num0;
8909
8910 case ASHIFT:
8911 /* Left shifts destroy copies. */
8912 if (GET_CODE (XEXP (x, 1)) != CONST_INT
8913 || INTVAL (XEXP (x, 1)) < 0
8914 || INTVAL (XEXP (x, 1)) >= (int) bitwidth)
8915 return 1;
8916
8917 num0 = num_sign_bit_copies_with_known (XEXP (x, 0), mode);
8918 return MAX (1, num0 - INTVAL (XEXP (x, 1)));
8919
8920 case IF_THEN_ELSE:
8921 num0 = num_sign_bit_copies_with_known (XEXP (x, 1), mode);
8922 num1 = num_sign_bit_copies_with_known (XEXP (x, 2), mode);
8923 return MIN (num0, num1);
8924
8925 case EQ: case NE: case GE: case GT: case LE: case LT:
8926 case UNEQ: case LTGT: case UNGE: case UNGT: case UNLE: case UNLT:
8927 case GEU: case GTU: case LEU: case LTU:
8928 case UNORDERED: case ORDERED:
8929 /* If the constant is negative, take its 1's complement and remask.
8930 Then see how many zero bits we have. */
8931 nonzero = STORE_FLAG_VALUE;
8932 if (bitwidth <= HOST_BITS_PER_WIDE_INT
8933 && (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
8934 nonzero = (~nonzero) & GET_MODE_MASK (mode);
8935
8936 return (nonzero == 0 ? bitwidth : bitwidth - floor_log2 (nonzero) - 1);
8937 break;
8938
8939 default:
8940 break;
8941 }
8942
8943 /* If we haven't been able to figure it out by one of the above rules,
8944 see if some of the high-order bits are known to be zero. If so,
8945 count those bits and return one less than that amount. If we can't
8946 safely compute the mask for this mode, always return BITWIDTH. */
8947
8948 if (bitwidth > HOST_BITS_PER_WIDE_INT)
8949 return 1;
8950
8951 nonzero = nonzero_bits (x, mode);
8952 return (nonzero & ((HOST_WIDE_INT) 1 << (bitwidth - 1))
8953 ? 1 : bitwidth - floor_log2 (nonzero) - 1);
8954 }
8955
8956 /* Return the number of "extended" bits there are in X, when interpreted
8957 as a quantity in MODE whose signedness is indicated by UNSIGNEDP. For
8958 unsigned quantities, this is the number of high-order zero bits.
8959 For signed quantities, this is the number of copies of the sign bit
8960 minus 1. In both case, this function returns the number of "spare"
8961 bits. For example, if two quantities for which this function returns
8962 at least 1 are added, the addition is known not to overflow.
8963
8964 This function will always return 0 unless called during combine, which
8965 implies that it must be called from a define_split. */
8966
8967 unsigned int
extended_count(rtx x,enum machine_mode mode,int unsignedp)8968 extended_count (rtx x, enum machine_mode mode, int unsignedp)
8969 {
8970 if (nonzero_sign_valid == 0)
8971 return 0;
8972
8973 return (unsignedp
8974 ? (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
8975 ? (unsigned int) (GET_MODE_BITSIZE (mode) - 1
8976 - floor_log2 (nonzero_bits (x, mode)))
8977 : 0)
8978 : num_sign_bit_copies (x, mode) - 1);
8979 }
8980
8981 /* This function is called from `simplify_shift_const' to merge two
8982 outer operations. Specifically, we have already found that we need
8983 to perform operation *POP0 with constant *PCONST0 at the outermost
8984 position. We would now like to also perform OP1 with constant CONST1
8985 (with *POP0 being done last).
8986
8987 Return 1 if we can do the operation and update *POP0 and *PCONST0 with
8988 the resulting operation. *PCOMP_P is set to 1 if we would need to
8989 complement the innermost operand, otherwise it is unchanged.
8990
8991 MODE is the mode in which the operation will be done. No bits outside
8992 the width of this mode matter. It is assumed that the width of this mode
8993 is smaller than or equal to HOST_BITS_PER_WIDE_INT.
8994
8995 If *POP0 or OP1 are NIL, it means no operation is required. Only NEG, PLUS,
8996 IOR, XOR, and AND are supported. We may set *POP0 to SET if the proper
8997 result is simply *PCONST0.
8998
8999 If the resulting operation cannot be expressed as one operation, we
9000 return 0 and do not change *POP0, *PCONST0, and *PCOMP_P. */
9001
9002 static int
merge_outer_ops(enum rtx_code * pop0,HOST_WIDE_INT * pconst0,enum rtx_code op1,HOST_WIDE_INT const1,enum machine_mode mode,int * pcomp_p)9003 merge_outer_ops (enum rtx_code *pop0, HOST_WIDE_INT *pconst0, enum rtx_code op1, HOST_WIDE_INT const1, enum machine_mode mode, int *pcomp_p)
9004 {
9005 enum rtx_code op0 = *pop0;
9006 HOST_WIDE_INT const0 = *pconst0;
9007
9008 const0 &= GET_MODE_MASK (mode);
9009 const1 &= GET_MODE_MASK (mode);
9010
9011 /* If OP0 is an AND, clear unimportant bits in CONST1. */
9012 if (op0 == AND)
9013 const1 &= const0;
9014
9015 /* If OP0 or OP1 is NIL, this is easy. Similarly if they are the same or
9016 if OP0 is SET. */
9017
9018 if (op1 == NIL || op0 == SET)
9019 return 1;
9020
9021 else if (op0 == NIL)
9022 op0 = op1, const0 = const1;
9023
9024 else if (op0 == op1)
9025 {
9026 switch (op0)
9027 {
9028 case AND:
9029 const0 &= const1;
9030 break;
9031 case IOR:
9032 const0 |= const1;
9033 break;
9034 case XOR:
9035 const0 ^= const1;
9036 break;
9037 case PLUS:
9038 const0 += const1;
9039 break;
9040 case NEG:
9041 op0 = NIL;
9042 break;
9043 default:
9044 break;
9045 }
9046 }
9047
9048 /* Otherwise, if either is a PLUS or NEG, we can't do anything. */
9049 else if (op0 == PLUS || op1 == PLUS || op0 == NEG || op1 == NEG)
9050 return 0;
9051
9052 /* If the two constants aren't the same, we can't do anything. The
9053 remaining six cases can all be done. */
9054 else if (const0 != const1)
9055 return 0;
9056
9057 else
9058 switch (op0)
9059 {
9060 case IOR:
9061 if (op1 == AND)
9062 /* (a & b) | b == b */
9063 op0 = SET;
9064 else /* op1 == XOR */
9065 /* (a ^ b) | b == a | b */
9066 {;}
9067 break;
9068
9069 case XOR:
9070 if (op1 == AND)
9071 /* (a & b) ^ b == (~a) & b */
9072 op0 = AND, *pcomp_p = 1;
9073 else /* op1 == IOR */
9074 /* (a | b) ^ b == a & ~b */
9075 op0 = AND, const0 = ~const0;
9076 break;
9077
9078 case AND:
9079 if (op1 == IOR)
9080 /* (a | b) & b == b */
9081 op0 = SET;
9082 else /* op1 == XOR */
9083 /* (a ^ b) & b) == (~a) & b */
9084 *pcomp_p = 1;
9085 break;
9086 default:
9087 break;
9088 }
9089
9090 /* Check for NO-OP cases. */
9091 const0 &= GET_MODE_MASK (mode);
9092 if (const0 == 0
9093 && (op0 == IOR || op0 == XOR || op0 == PLUS))
9094 op0 = NIL;
9095 else if (const0 == 0 && op0 == AND)
9096 op0 = SET;
9097 else if ((unsigned HOST_WIDE_INT) const0 == GET_MODE_MASK (mode)
9098 && op0 == AND)
9099 op0 = NIL;
9100
9101 /* ??? Slightly redundant with the above mask, but not entirely.
9102 Moving this above means we'd have to sign-extend the mode mask
9103 for the final test. */
9104 const0 = trunc_int_for_mode (const0, mode);
9105
9106 *pop0 = op0;
9107 *pconst0 = const0;
9108
9109 return 1;
9110 }
9111
9112 /* Simplify a shift of VAROP by COUNT bits. CODE says what kind of shift.
9113 The result of the shift is RESULT_MODE. X, if nonzero, is an expression
9114 that we started with.
9115
9116 The shift is normally computed in the widest mode we find in VAROP, as
9117 long as it isn't a different number of words than RESULT_MODE. Exceptions
9118 are ASHIFTRT and ROTATE, which are always done in their original mode, */
9119
9120 static rtx
simplify_shift_const(rtx x,enum rtx_code code,enum machine_mode result_mode,rtx varop,int orig_count)9121 simplify_shift_const (rtx x, enum rtx_code code,
9122 enum machine_mode result_mode, rtx varop,
9123 int orig_count)
9124 {
9125 enum rtx_code orig_code = code;
9126 unsigned int count;
9127 int signed_count;
9128 enum machine_mode mode = result_mode;
9129 enum machine_mode shift_mode, tmode;
9130 unsigned int mode_words
9131 = (GET_MODE_SIZE (mode) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD;
9132 /* We form (outer_op (code varop count) (outer_const)). */
9133 enum rtx_code outer_op = NIL;
9134 HOST_WIDE_INT outer_const = 0;
9135 rtx const_rtx;
9136 int complement_p = 0;
9137 rtx new;
9138
9139 /* Make sure and truncate the "natural" shift on the way in. We don't
9140 want to do this inside the loop as it makes it more difficult to
9141 combine shifts. */
9142 if (SHIFT_COUNT_TRUNCATED)
9143 orig_count &= GET_MODE_BITSIZE (mode) - 1;
9144
9145 /* If we were given an invalid count, don't do anything except exactly
9146 what was requested. */
9147
9148 if (orig_count < 0 || orig_count >= (int) GET_MODE_BITSIZE (mode))
9149 {
9150 if (x)
9151 return x;
9152
9153 return gen_rtx_fmt_ee (code, mode, varop, GEN_INT (orig_count));
9154 }
9155
9156 count = orig_count;
9157
9158 /* Unless one of the branches of the `if' in this loop does a `continue',
9159 we will `break' the loop after the `if'. */
9160
9161 while (count != 0)
9162 {
9163 /* If we have an operand of (clobber (const_int 0)), just return that
9164 value. */
9165 if (GET_CODE (varop) == CLOBBER)
9166 return varop;
9167
9168 /* If we discovered we had to complement VAROP, leave. Making a NOT
9169 here would cause an infinite loop. */
9170 if (complement_p)
9171 break;
9172
9173 /* Convert ROTATERT to ROTATE. */
9174 if (code == ROTATERT)
9175 {
9176 unsigned int bitsize = GET_MODE_BITSIZE (result_mode);;
9177 code = ROTATE;
9178 if (VECTOR_MODE_P (result_mode))
9179 count = bitsize / GET_MODE_NUNITS (result_mode) - count;
9180 else
9181 count = bitsize - count;
9182 }
9183
9184 /* We need to determine what mode we will do the shift in. If the
9185 shift is a right shift or a ROTATE, we must always do it in the mode
9186 it was originally done in. Otherwise, we can do it in MODE, the
9187 widest mode encountered. */
9188 shift_mode
9189 = (code == ASHIFTRT || code == LSHIFTRT || code == ROTATE
9190 ? result_mode : mode);
9191
9192 /* Handle cases where the count is greater than the size of the mode
9193 minus 1. For ASHIFT, use the size minus one as the count (this can
9194 occur when simplifying (lshiftrt (ashiftrt ..))). For rotates,
9195 take the count modulo the size. For other shifts, the result is
9196 zero.
9197
9198 Since these shifts are being produced by the compiler by combining
9199 multiple operations, each of which are defined, we know what the
9200 result is supposed to be. */
9201
9202 if (count > (unsigned int) (GET_MODE_BITSIZE (shift_mode) - 1))
9203 {
9204 if (code == ASHIFTRT)
9205 count = GET_MODE_BITSIZE (shift_mode) - 1;
9206 else if (code == ROTATE || code == ROTATERT)
9207 count %= GET_MODE_BITSIZE (shift_mode);
9208 else
9209 {
9210 /* We can't simply return zero because there may be an
9211 outer op. */
9212 varop = const0_rtx;
9213 count = 0;
9214 break;
9215 }
9216 }
9217
9218 /* An arithmetic right shift of a quantity known to be -1 or 0
9219 is a no-op. */
9220 if (code == ASHIFTRT
9221 && (num_sign_bit_copies (varop, shift_mode)
9222 == GET_MODE_BITSIZE (shift_mode)))
9223 {
9224 count = 0;
9225 break;
9226 }
9227
9228 /* If we are doing an arithmetic right shift and discarding all but
9229 the sign bit copies, this is equivalent to doing a shift by the
9230 bitsize minus one. Convert it into that shift because it will often
9231 allow other simplifications. */
9232
9233 if (code == ASHIFTRT
9234 && (count + num_sign_bit_copies (varop, shift_mode)
9235 >= GET_MODE_BITSIZE (shift_mode)))
9236 count = GET_MODE_BITSIZE (shift_mode) - 1;
9237
9238 /* We simplify the tests below and elsewhere by converting
9239 ASHIFTRT to LSHIFTRT if we know the sign bit is clear.
9240 `make_compound_operation' will convert it to an ASHIFTRT for
9241 those machines (such as VAX) that don't have an LSHIFTRT. */
9242 if (GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT
9243 && code == ASHIFTRT
9244 && ((nonzero_bits (varop, shift_mode)
9245 & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (shift_mode) - 1)))
9246 == 0))
9247 code = LSHIFTRT;
9248
9249 if (code == LSHIFTRT
9250 && GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT
9251 && !(nonzero_bits (varop, shift_mode) >> count))
9252 varop = const0_rtx;
9253 if (code == ASHIFT
9254 && GET_MODE_BITSIZE (shift_mode) <= HOST_BITS_PER_WIDE_INT
9255 && !((nonzero_bits (varop, shift_mode) << count)
9256 & GET_MODE_MASK (shift_mode)))
9257 varop = const0_rtx;
9258
9259 switch (GET_CODE (varop))
9260 {
9261 case SIGN_EXTEND:
9262 case ZERO_EXTEND:
9263 case SIGN_EXTRACT:
9264 case ZERO_EXTRACT:
9265 new = expand_compound_operation (varop);
9266 if (new != varop)
9267 {
9268 varop = new;
9269 continue;
9270 }
9271 break;
9272
9273 case MEM:
9274 /* If we have (xshiftrt (mem ...) C) and C is MODE_WIDTH
9275 minus the width of a smaller mode, we can do this with a
9276 SIGN_EXTEND or ZERO_EXTEND from the narrower memory location. */
9277 if ((code == ASHIFTRT || code == LSHIFTRT)
9278 && ! mode_dependent_address_p (XEXP (varop, 0))
9279 && ! MEM_VOLATILE_P (varop)
9280 && (tmode = mode_for_size (GET_MODE_BITSIZE (mode) - count,
9281 MODE_INT, 1)) != BLKmode)
9282 {
9283 new = adjust_address_nv (varop, tmode,
9284 BYTES_BIG_ENDIAN ? 0
9285 : count / BITS_PER_UNIT);
9286
9287 varop = gen_rtx_fmt_e (code == ASHIFTRT ? SIGN_EXTEND
9288 : ZERO_EXTEND, mode, new);
9289 count = 0;
9290 continue;
9291 }
9292 break;
9293
9294 case USE:
9295 /* Similar to the case above, except that we can only do this if
9296 the resulting mode is the same as that of the underlying
9297 MEM and adjust the address depending on the *bits* endianness
9298 because of the way that bit-field extract insns are defined. */
9299 if ((code == ASHIFTRT || code == LSHIFTRT)
9300 && (tmode = mode_for_size (GET_MODE_BITSIZE (mode) - count,
9301 MODE_INT, 1)) != BLKmode
9302 && tmode == GET_MODE (XEXP (varop, 0)))
9303 {
9304 if (BITS_BIG_ENDIAN)
9305 new = XEXP (varop, 0);
9306 else
9307 {
9308 new = copy_rtx (XEXP (varop, 0));
9309 SUBST (XEXP (new, 0),
9310 plus_constant (XEXP (new, 0),
9311 count / BITS_PER_UNIT));
9312 }
9313
9314 varop = gen_rtx_fmt_e (code == ASHIFTRT ? SIGN_EXTEND
9315 : ZERO_EXTEND, mode, new);
9316 count = 0;
9317 continue;
9318 }
9319 break;
9320
9321 case SUBREG:
9322 /* If VAROP is a SUBREG, strip it as long as the inner operand has
9323 the same number of words as what we've seen so far. Then store
9324 the widest mode in MODE. */
9325 if (subreg_lowpart_p (varop)
9326 && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (varop)))
9327 > GET_MODE_SIZE (GET_MODE (varop)))
9328 && (unsigned int) ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (varop)))
9329 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
9330 == mode_words)
9331 {
9332 varop = SUBREG_REG (varop);
9333 if (GET_MODE_SIZE (GET_MODE (varop)) > GET_MODE_SIZE (mode))
9334 mode = GET_MODE (varop);
9335 continue;
9336 }
9337 break;
9338
9339 case MULT:
9340 /* Some machines use MULT instead of ASHIFT because MULT
9341 is cheaper. But it is still better on those machines to
9342 merge two shifts into one. */
9343 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
9344 && exact_log2 (INTVAL (XEXP (varop, 1))) >= 0)
9345 {
9346 varop
9347 = gen_binary (ASHIFT, GET_MODE (varop), XEXP (varop, 0),
9348 GEN_INT (exact_log2 (INTVAL (XEXP (varop, 1)))));
9349 continue;
9350 }
9351 break;
9352
9353 case UDIV:
9354 /* Similar, for when divides are cheaper. */
9355 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
9356 && exact_log2 (INTVAL (XEXP (varop, 1))) >= 0)
9357 {
9358 varop
9359 = gen_binary (LSHIFTRT, GET_MODE (varop), XEXP (varop, 0),
9360 GEN_INT (exact_log2 (INTVAL (XEXP (varop, 1)))));
9361 continue;
9362 }
9363 break;
9364
9365 case ASHIFTRT:
9366 /* If we are extracting just the sign bit of an arithmetic
9367 right shift, that shift is not needed. However, the sign
9368 bit of a wider mode may be different from what would be
9369 interpreted as the sign bit in a narrower mode, so, if
9370 the result is narrower, don't discard the shift. */
9371 if (code == LSHIFTRT
9372 && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
9373 && (GET_MODE_BITSIZE (result_mode)
9374 >= GET_MODE_BITSIZE (GET_MODE (varop))))
9375 {
9376 varop = XEXP (varop, 0);
9377 continue;
9378 }
9379
9380 /* ... fall through ... */
9381
9382 case LSHIFTRT:
9383 case ASHIFT:
9384 case ROTATE:
9385 /* Here we have two nested shifts. The result is usually the
9386 AND of a new shift with a mask. We compute the result below. */
9387 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
9388 && INTVAL (XEXP (varop, 1)) >= 0
9389 && INTVAL (XEXP (varop, 1)) < GET_MODE_BITSIZE (GET_MODE (varop))
9390 && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
9391 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
9392 {
9393 enum rtx_code first_code = GET_CODE (varop);
9394 unsigned int first_count = INTVAL (XEXP (varop, 1));
9395 unsigned HOST_WIDE_INT mask;
9396 rtx mask_rtx;
9397
9398 /* We have one common special case. We can't do any merging if
9399 the inner code is an ASHIFTRT of a smaller mode. However, if
9400 we have (ashift:M1 (subreg:M1 (ashiftrt:M2 FOO C1) 0) C2)
9401 with C2 == GET_MODE_BITSIZE (M1) - GET_MODE_BITSIZE (M2),
9402 we can convert it to
9403 (ashiftrt:M1 (ashift:M1 (and:M1 (subreg:M1 FOO 0 C2) C3) C1).
9404 This simplifies certain SIGN_EXTEND operations. */
9405 if (code == ASHIFT && first_code == ASHIFTRT
9406 && count == (unsigned int)
9407 (GET_MODE_BITSIZE (result_mode)
9408 - GET_MODE_BITSIZE (GET_MODE (varop))))
9409 {
9410 /* C3 has the low-order C1 bits zero. */
9411
9412 mask = (GET_MODE_MASK (mode)
9413 & ~(((HOST_WIDE_INT) 1 << first_count) - 1));
9414
9415 varop = simplify_and_const_int (NULL_RTX, result_mode,
9416 XEXP (varop, 0), mask);
9417 varop = simplify_shift_const (NULL_RTX, ASHIFT, result_mode,
9418 varop, count);
9419 count = first_count;
9420 code = ASHIFTRT;
9421 continue;
9422 }
9423
9424 /* If this was (ashiftrt (ashift foo C1) C2) and FOO has more
9425 than C1 high-order bits equal to the sign bit, we can convert
9426 this to either an ASHIFT or an ASHIFTRT depending on the
9427 two counts.
9428
9429 We cannot do this if VAROP's mode is not SHIFT_MODE. */
9430
9431 if (code == ASHIFTRT && first_code == ASHIFT
9432 && GET_MODE (varop) == shift_mode
9433 && (num_sign_bit_copies (XEXP (varop, 0), shift_mode)
9434 > first_count))
9435 {
9436 varop = XEXP (varop, 0);
9437
9438 signed_count = count - first_count;
9439 if (signed_count < 0)
9440 count = -signed_count, code = ASHIFT;
9441 else
9442 count = signed_count;
9443
9444 continue;
9445 }
9446
9447 /* There are some cases we can't do. If CODE is ASHIFTRT,
9448 we can only do this if FIRST_CODE is also ASHIFTRT.
9449
9450 We can't do the case when CODE is ROTATE and FIRST_CODE is
9451 ASHIFTRT.
9452
9453 If the mode of this shift is not the mode of the outer shift,
9454 we can't do this if either shift is a right shift or ROTATE.
9455
9456 Finally, we can't do any of these if the mode is too wide
9457 unless the codes are the same.
9458
9459 Handle the case where the shift codes are the same
9460 first. */
9461
9462 if (code == first_code)
9463 {
9464 if (GET_MODE (varop) != result_mode
9465 && (code == ASHIFTRT || code == LSHIFTRT
9466 || code == ROTATE))
9467 break;
9468
9469 count += first_count;
9470 varop = XEXP (varop, 0);
9471 continue;
9472 }
9473
9474 if (code == ASHIFTRT
9475 || (code == ROTATE && first_code == ASHIFTRT)
9476 || GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT
9477 || (GET_MODE (varop) != result_mode
9478 && (first_code == ASHIFTRT || first_code == LSHIFTRT
9479 || first_code == ROTATE
9480 || code == ROTATE)))
9481 break;
9482
9483 /* To compute the mask to apply after the shift, shift the
9484 nonzero bits of the inner shift the same way the
9485 outer shift will. */
9486
9487 mask_rtx = GEN_INT (nonzero_bits (varop, GET_MODE (varop)));
9488
9489 mask_rtx
9490 = simplify_binary_operation (code, result_mode, mask_rtx,
9491 GEN_INT (count));
9492
9493 /* Give up if we can't compute an outer operation to use. */
9494 if (mask_rtx == 0
9495 || GET_CODE (mask_rtx) != CONST_INT
9496 || ! merge_outer_ops (&outer_op, &outer_const, AND,
9497 INTVAL (mask_rtx),
9498 result_mode, &complement_p))
9499 break;
9500
9501 /* If the shifts are in the same direction, we add the
9502 counts. Otherwise, we subtract them. */
9503 signed_count = count;
9504 if ((code == ASHIFTRT || code == LSHIFTRT)
9505 == (first_code == ASHIFTRT || first_code == LSHIFTRT))
9506 signed_count += first_count;
9507 else
9508 signed_count -= first_count;
9509
9510 /* If COUNT is positive, the new shift is usually CODE,
9511 except for the two exceptions below, in which case it is
9512 FIRST_CODE. If the count is negative, FIRST_CODE should
9513 always be used */
9514 if (signed_count > 0
9515 && ((first_code == ROTATE && code == ASHIFT)
9516 || (first_code == ASHIFTRT && code == LSHIFTRT)))
9517 code = first_code, count = signed_count;
9518 else if (signed_count < 0)
9519 code = first_code, count = -signed_count;
9520 else
9521 count = signed_count;
9522
9523 varop = XEXP (varop, 0);
9524 continue;
9525 }
9526
9527 /* If we have (A << B << C) for any shift, we can convert this to
9528 (A << C << B). This wins if A is a constant. Only try this if
9529 B is not a constant. */
9530
9531 else if (GET_CODE (varop) == code
9532 && GET_CODE (XEXP (varop, 1)) != CONST_INT
9533 && 0 != (new
9534 = simplify_binary_operation (code, mode,
9535 XEXP (varop, 0),
9536 GEN_INT (count))))
9537 {
9538 varop = gen_rtx_fmt_ee (code, mode, new, XEXP (varop, 1));
9539 count = 0;
9540 continue;
9541 }
9542 break;
9543
9544 case NOT:
9545 /* Make this fit the case below. */
9546 varop = gen_rtx_XOR (mode, XEXP (varop, 0),
9547 GEN_INT (GET_MODE_MASK (mode)));
9548 continue;
9549
9550 case IOR:
9551 case AND:
9552 case XOR:
9553 /* If we have (xshiftrt (ior (plus X (const_int -1)) X) C)
9554 with C the size of VAROP - 1 and the shift is logical if
9555 STORE_FLAG_VALUE is 1 and arithmetic if STORE_FLAG_VALUE is -1,
9556 we have an (le X 0) operation. If we have an arithmetic shift
9557 and STORE_FLAG_VALUE is 1 or we have a logical shift with
9558 STORE_FLAG_VALUE of -1, we have a (neg (le X 0)) operation. */
9559
9560 if (GET_CODE (varop) == IOR && GET_CODE (XEXP (varop, 0)) == PLUS
9561 && XEXP (XEXP (varop, 0), 1) == constm1_rtx
9562 && (STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
9563 && (code == LSHIFTRT || code == ASHIFTRT)
9564 && count == (unsigned int)
9565 (GET_MODE_BITSIZE (GET_MODE (varop)) - 1)
9566 && rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1)))
9567 {
9568 count = 0;
9569 varop = gen_rtx_LE (GET_MODE (varop), XEXP (varop, 1),
9570 const0_rtx);
9571
9572 if (STORE_FLAG_VALUE == 1 ? code == ASHIFTRT : code == LSHIFTRT)
9573 varop = gen_rtx_NEG (GET_MODE (varop), varop);
9574
9575 continue;
9576 }
9577
9578 /* If we have (shift (logical)), move the logical to the outside
9579 to allow it to possibly combine with another logical and the
9580 shift to combine with another shift. This also canonicalizes to
9581 what a ZERO_EXTRACT looks like. Also, some machines have
9582 (and (shift)) insns. */
9583
9584 if (GET_CODE (XEXP (varop, 1)) == CONST_INT
9585 && (new = simplify_binary_operation (code, result_mode,
9586 XEXP (varop, 1),
9587 GEN_INT (count))) != 0
9588 && GET_CODE (new) == CONST_INT
9589 && merge_outer_ops (&outer_op, &outer_const, GET_CODE (varop),
9590 INTVAL (new), result_mode, &complement_p))
9591 {
9592 varop = XEXP (varop, 0);
9593 continue;
9594 }
9595
9596 /* If we can't do that, try to simplify the shift in each arm of the
9597 logical expression, make a new logical expression, and apply
9598 the inverse distributive law. */
9599 {
9600 rtx lhs = simplify_shift_const (NULL_RTX, code, shift_mode,
9601 XEXP (varop, 0), count);
9602 rtx rhs = simplify_shift_const (NULL_RTX, code, shift_mode,
9603 XEXP (varop, 1), count);
9604
9605 varop = gen_binary (GET_CODE (varop), shift_mode, lhs, rhs);
9606 varop = apply_distributive_law (varop);
9607
9608 count = 0;
9609 }
9610 break;
9611
9612 case EQ:
9613 /* Convert (lshiftrt (eq FOO 0) C) to (xor FOO 1) if STORE_FLAG_VALUE
9614 says that the sign bit can be tested, FOO has mode MODE, C is
9615 GET_MODE_BITSIZE (MODE) - 1, and FOO has only its low-order bit
9616 that may be nonzero. */
9617 if (code == LSHIFTRT
9618 && XEXP (varop, 1) == const0_rtx
9619 && GET_MODE (XEXP (varop, 0)) == result_mode
9620 && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
9621 && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
9622 && ((STORE_FLAG_VALUE
9623 & ((HOST_WIDE_INT) 1
9624 < (GET_MODE_BITSIZE (result_mode) - 1))))
9625 && nonzero_bits (XEXP (varop, 0), result_mode) == 1
9626 && merge_outer_ops (&outer_op, &outer_const, XOR,
9627 (HOST_WIDE_INT) 1, result_mode,
9628 &complement_p))
9629 {
9630 varop = XEXP (varop, 0);
9631 count = 0;
9632 continue;
9633 }
9634 break;
9635
9636 case NEG:
9637 /* (lshiftrt (neg A) C) where A is either 0 or 1 and C is one less
9638 than the number of bits in the mode is equivalent to A. */
9639 if (code == LSHIFTRT
9640 && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
9641 && nonzero_bits (XEXP (varop, 0), result_mode) == 1)
9642 {
9643 varop = XEXP (varop, 0);
9644 count = 0;
9645 continue;
9646 }
9647
9648 /* NEG commutes with ASHIFT since it is multiplication. Move the
9649 NEG outside to allow shifts to combine. */
9650 if (code == ASHIFT
9651 && merge_outer_ops (&outer_op, &outer_const, NEG,
9652 (HOST_WIDE_INT) 0, result_mode,
9653 &complement_p))
9654 {
9655 varop = XEXP (varop, 0);
9656 continue;
9657 }
9658 break;
9659
9660 case PLUS:
9661 /* (lshiftrt (plus A -1) C) where A is either 0 or 1 and C
9662 is one less than the number of bits in the mode is
9663 equivalent to (xor A 1). */
9664 if (code == LSHIFTRT
9665 && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
9666 && XEXP (varop, 1) == constm1_rtx
9667 && nonzero_bits (XEXP (varop, 0), result_mode) == 1
9668 && merge_outer_ops (&outer_op, &outer_const, XOR,
9669 (HOST_WIDE_INT) 1, result_mode,
9670 &complement_p))
9671 {
9672 count = 0;
9673 varop = XEXP (varop, 0);
9674 continue;
9675 }
9676
9677 /* If we have (xshiftrt (plus FOO BAR) C), and the only bits
9678 that might be nonzero in BAR are those being shifted out and those
9679 bits are known zero in FOO, we can replace the PLUS with FOO.
9680 Similarly in the other operand order. This code occurs when
9681 we are computing the size of a variable-size array. */
9682
9683 if ((code == ASHIFTRT || code == LSHIFTRT)
9684 && count < HOST_BITS_PER_WIDE_INT
9685 && nonzero_bits (XEXP (varop, 1), result_mode) >> count == 0
9686 && (nonzero_bits (XEXP (varop, 1), result_mode)
9687 & nonzero_bits (XEXP (varop, 0), result_mode)) == 0)
9688 {
9689 varop = XEXP (varop, 0);
9690 continue;
9691 }
9692 else if ((code == ASHIFTRT || code == LSHIFTRT)
9693 && count < HOST_BITS_PER_WIDE_INT
9694 && GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
9695 && 0 == (nonzero_bits (XEXP (varop, 0), result_mode)
9696 >> count)
9697 && 0 == (nonzero_bits (XEXP (varop, 0), result_mode)
9698 & nonzero_bits (XEXP (varop, 1),
9699 result_mode)))
9700 {
9701 varop = XEXP (varop, 1);
9702 continue;
9703 }
9704
9705 /* (ashift (plus foo C) N) is (plus (ashift foo N) C'). */
9706 if (code == ASHIFT
9707 && GET_CODE (XEXP (varop, 1)) == CONST_INT
9708 && (new = simplify_binary_operation (ASHIFT, result_mode,
9709 XEXP (varop, 1),
9710 GEN_INT (count))) != 0
9711 && GET_CODE (new) == CONST_INT
9712 && merge_outer_ops (&outer_op, &outer_const, PLUS,
9713 INTVAL (new), result_mode, &complement_p))
9714 {
9715 varop = XEXP (varop, 0);
9716 continue;
9717 }
9718 break;
9719
9720 case MINUS:
9721 /* If we have (xshiftrt (minus (ashiftrt X C)) X) C)
9722 with C the size of VAROP - 1 and the shift is logical if
9723 STORE_FLAG_VALUE is 1 and arithmetic if STORE_FLAG_VALUE is -1,
9724 we have a (gt X 0) operation. If the shift is arithmetic with
9725 STORE_FLAG_VALUE of 1 or logical with STORE_FLAG_VALUE == -1,
9726 we have a (neg (gt X 0)) operation. */
9727
9728 if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
9729 && GET_CODE (XEXP (varop, 0)) == ASHIFTRT
9730 && count == (unsigned int)
9731 (GET_MODE_BITSIZE (GET_MODE (varop)) - 1)
9732 && (code == LSHIFTRT || code == ASHIFTRT)
9733 && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT
9734 && (unsigned HOST_WIDE_INT) INTVAL (XEXP (XEXP (varop, 0), 1))
9735 == count
9736 && rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1)))
9737 {
9738 count = 0;
9739 varop = gen_rtx_GT (GET_MODE (varop), XEXP (varop, 1),
9740 const0_rtx);
9741
9742 if (STORE_FLAG_VALUE == 1 ? code == ASHIFTRT : code == LSHIFTRT)
9743 varop = gen_rtx_NEG (GET_MODE (varop), varop);
9744
9745 continue;
9746 }
9747 break;
9748
9749 case TRUNCATE:
9750 /* Change (lshiftrt (truncate (lshiftrt))) to (truncate (lshiftrt))
9751 if the truncate does not affect the value. */
9752 if (code == LSHIFTRT
9753 && GET_CODE (XEXP (varop, 0)) == LSHIFTRT
9754 && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT
9755 && (INTVAL (XEXP (XEXP (varop, 0), 1))
9756 >= (GET_MODE_BITSIZE (GET_MODE (XEXP (varop, 0)))
9757 - GET_MODE_BITSIZE (GET_MODE (varop)))))
9758 {
9759 rtx varop_inner = XEXP (varop, 0);
9760
9761 varop_inner
9762 = gen_rtx_LSHIFTRT (GET_MODE (varop_inner),
9763 XEXP (varop_inner, 0),
9764 GEN_INT
9765 (count + INTVAL (XEXP (varop_inner, 1))));
9766 varop = gen_rtx_TRUNCATE (GET_MODE (varop), varop_inner);
9767 count = 0;
9768 continue;
9769 }
9770 break;
9771
9772 default:
9773 break;
9774 }
9775
9776 break;
9777 }
9778
9779 /* We need to determine what mode to do the shift in. If the shift is
9780 a right shift or ROTATE, we must always do it in the mode it was
9781 originally done in. Otherwise, we can do it in MODE, the widest mode
9782 encountered. The code we care about is that of the shift that will
9783 actually be done, not the shift that was originally requested. */
9784 shift_mode
9785 = (code == ASHIFTRT || code == LSHIFTRT || code == ROTATE
9786 ? result_mode : mode);
9787
9788 /* We have now finished analyzing the shift. The result should be
9789 a shift of type CODE with SHIFT_MODE shifting VAROP COUNT places. If
9790 OUTER_OP is non-NIL, it is an operation that needs to be applied
9791 to the result of the shift. OUTER_CONST is the relevant constant,
9792 but we must turn off all bits turned off in the shift.
9793
9794 If we were passed a value for X, see if we can use any pieces of
9795 it. If not, make new rtx. */
9796
9797 if (x && GET_RTX_CLASS (GET_CODE (x)) == '2'
9798 && GET_CODE (XEXP (x, 1)) == CONST_INT
9799 && (unsigned HOST_WIDE_INT) INTVAL (XEXP (x, 1)) == count)
9800 const_rtx = XEXP (x, 1);
9801 else
9802 const_rtx = GEN_INT (count);
9803
9804 if (x && GET_CODE (XEXP (x, 0)) == SUBREG
9805 && GET_MODE (XEXP (x, 0)) == shift_mode
9806 && SUBREG_REG (XEXP (x, 0)) == varop)
9807 varop = XEXP (x, 0);
9808 else if (GET_MODE (varop) != shift_mode)
9809 varop = gen_lowpart_for_combine (shift_mode, varop);
9810
9811 /* If we can't make the SUBREG, try to return what we were given. */
9812 if (GET_CODE (varop) == CLOBBER)
9813 return x ? x : varop;
9814
9815 new = simplify_binary_operation (code, shift_mode, varop, const_rtx);
9816 if (new != 0)
9817 x = new;
9818 else
9819 x = gen_rtx_fmt_ee (code, shift_mode, varop, const_rtx);
9820
9821 /* If we have an outer operation and we just made a shift, it is
9822 possible that we could have simplified the shift were it not
9823 for the outer operation. So try to do the simplification
9824 recursively. */
9825
9826 if (outer_op != NIL && GET_CODE (x) == code
9827 && GET_CODE (XEXP (x, 1)) == CONST_INT)
9828 x = simplify_shift_const (x, code, shift_mode, XEXP (x, 0),
9829 INTVAL (XEXP (x, 1)));
9830
9831 /* If we were doing an LSHIFTRT in a wider mode than it was originally,
9832 turn off all the bits that the shift would have turned off. */
9833 if (orig_code == LSHIFTRT && result_mode != shift_mode)
9834 x = simplify_and_const_int (NULL_RTX, shift_mode, x,
9835 GET_MODE_MASK (result_mode) >> orig_count);
9836
9837 /* Do the remainder of the processing in RESULT_MODE. */
9838 x = gen_lowpart_for_combine (result_mode, x);
9839
9840 /* If COMPLEMENT_P is set, we have to complement X before doing the outer
9841 operation. */
9842 if (complement_p)
9843 x = simplify_gen_unary (NOT, result_mode, x, result_mode);
9844
9845 if (outer_op != NIL)
9846 {
9847 if (GET_MODE_BITSIZE (result_mode) < HOST_BITS_PER_WIDE_INT)
9848 outer_const = trunc_int_for_mode (outer_const, result_mode);
9849
9850 if (outer_op == AND)
9851 x = simplify_and_const_int (NULL_RTX, result_mode, x, outer_const);
9852 else if (outer_op == SET)
9853 /* This means that we have determined that the result is
9854 equivalent to a constant. This should be rare. */
9855 x = GEN_INT (outer_const);
9856 else if (GET_RTX_CLASS (outer_op) == '1')
9857 x = simplify_gen_unary (outer_op, result_mode, x, result_mode);
9858 else
9859 x = gen_binary (outer_op, result_mode, x, GEN_INT (outer_const));
9860 }
9861
9862 return x;
9863 }
9864
9865 /* Like recog, but we receive the address of a pointer to a new pattern.
9866 We try to match the rtx that the pointer points to.
9867 If that fails, we may try to modify or replace the pattern,
9868 storing the replacement into the same pointer object.
9869
9870 Modifications include deletion or addition of CLOBBERs.
9871
9872 PNOTES is a pointer to a location where any REG_UNUSED notes added for
9873 the CLOBBERs are placed.
9874
9875 The value is the final insn code from the pattern ultimately matched,
9876 or -1. */
9877
9878 static int
recog_for_combine(rtx * pnewpat,rtx insn,rtx * pnotes)9879 recog_for_combine (rtx *pnewpat, rtx insn, rtx *pnotes)
9880 {
9881 rtx pat = *pnewpat;
9882 int insn_code_number;
9883 int num_clobbers_to_add = 0;
9884 int i;
9885 rtx notes = 0;
9886 rtx old_notes, old_pat;
9887
9888 /* If PAT is a PARALLEL, check to see if it contains the CLOBBER
9889 we use to indicate that something didn't match. If we find such a
9890 thing, force rejection. */
9891 if (GET_CODE (pat) == PARALLEL)
9892 for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
9893 if (GET_CODE (XVECEXP (pat, 0, i)) == CLOBBER
9894 && XEXP (XVECEXP (pat, 0, i), 0) == const0_rtx)
9895 return -1;
9896
9897 old_pat = PATTERN (insn);
9898 old_notes = REG_NOTES (insn);
9899 PATTERN (insn) = pat;
9900 REG_NOTES (insn) = 0;
9901
9902 insn_code_number = recog (pat, insn, &num_clobbers_to_add);
9903
9904 /* If it isn't, there is the possibility that we previously had an insn
9905 that clobbered some register as a side effect, but the combined
9906 insn doesn't need to do that. So try once more without the clobbers
9907 unless this represents an ASM insn. */
9908
9909 if (insn_code_number < 0 && ! check_asm_operands (pat)
9910 && GET_CODE (pat) == PARALLEL)
9911 {
9912 int pos;
9913
9914 for (pos = 0, i = 0; i < XVECLEN (pat, 0); i++)
9915 if (GET_CODE (XVECEXP (pat, 0, i)) != CLOBBER)
9916 {
9917 if (i != pos)
9918 SUBST (XVECEXP (pat, 0, pos), XVECEXP (pat, 0, i));
9919 pos++;
9920 }
9921
9922 SUBST_INT (XVECLEN (pat, 0), pos);
9923
9924 if (pos == 1)
9925 pat = XVECEXP (pat, 0, 0);
9926
9927 PATTERN (insn) = pat;
9928 insn_code_number = recog (pat, insn, &num_clobbers_to_add);
9929 }
9930 PATTERN (insn) = old_pat;
9931 REG_NOTES (insn) = old_notes;
9932
9933 /* Recognize all noop sets, these will be killed by followup pass. */
9934 if (insn_code_number < 0 && GET_CODE (pat) == SET && set_noop_p (pat))
9935 insn_code_number = NOOP_MOVE_INSN_CODE, num_clobbers_to_add = 0;
9936
9937 /* If we had any clobbers to add, make a new pattern than contains
9938 them. Then check to make sure that all of them are dead. */
9939 if (num_clobbers_to_add)
9940 {
9941 rtx newpat = gen_rtx_PARALLEL (VOIDmode,
9942 rtvec_alloc (GET_CODE (pat) == PARALLEL
9943 ? (XVECLEN (pat, 0)
9944 + num_clobbers_to_add)
9945 : num_clobbers_to_add + 1));
9946
9947 if (GET_CODE (pat) == PARALLEL)
9948 for (i = 0; i < XVECLEN (pat, 0); i++)
9949 XVECEXP (newpat, 0, i) = XVECEXP (pat, 0, i);
9950 else
9951 XVECEXP (newpat, 0, 0) = pat;
9952
9953 add_clobbers (newpat, insn_code_number);
9954
9955 for (i = XVECLEN (newpat, 0) - num_clobbers_to_add;
9956 i < XVECLEN (newpat, 0); i++)
9957 {
9958 if (GET_CODE (XEXP (XVECEXP (newpat, 0, i), 0)) == REG
9959 && ! reg_dead_at_p (XEXP (XVECEXP (newpat, 0, i), 0), insn))
9960 return -1;
9961 notes = gen_rtx_EXPR_LIST (REG_UNUSED,
9962 XEXP (XVECEXP (newpat, 0, i), 0), notes);
9963 }
9964 pat = newpat;
9965 }
9966
9967 *pnewpat = pat;
9968 *pnotes = notes;
9969
9970 return insn_code_number;
9971 }
9972
9973 /* Like gen_lowpart but for use by combine. In combine it is not possible
9974 to create any new pseudoregs. However, it is safe to create
9975 invalid memory addresses, because combine will try to recognize
9976 them and all they will do is make the combine attempt fail.
9977
9978 If for some reason this cannot do its job, an rtx
9979 (clobber (const_int 0)) is returned.
9980 An insn containing that will not be recognized. */
9981
9982 #undef gen_lowpart
9983
9984 static rtx
gen_lowpart_for_combine(enum machine_mode mode,rtx x)9985 gen_lowpart_for_combine (enum machine_mode mode, rtx x)
9986 {
9987 rtx result;
9988
9989 if (GET_MODE (x) == mode)
9990 return x;
9991
9992 /* Return identity if this is a CONST or symbolic
9993 reference. */
9994 if (mode == Pmode
9995 && (GET_CODE (x) == CONST
9996 || GET_CODE (x) == SYMBOL_REF
9997 || GET_CODE (x) == LABEL_REF))
9998 return x;
9999
10000 /* We can only support MODE being wider than a word if X is a
10001 constant integer or has a mode the same size. */
10002
10003 if (GET_MODE_SIZE (mode) > UNITS_PER_WORD
10004 && ! ((GET_MODE (x) == VOIDmode
10005 && (GET_CODE (x) == CONST_INT
10006 || GET_CODE (x) == CONST_DOUBLE))
10007 || GET_MODE_SIZE (GET_MODE (x)) == GET_MODE_SIZE (mode)))
10008 return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx);
10009
10010 /* X might be a paradoxical (subreg (mem)). In that case, gen_lowpart
10011 won't know what to do. So we will strip off the SUBREG here and
10012 process normally. */
10013 if (GET_CODE (x) == SUBREG && GET_CODE (SUBREG_REG (x)) == MEM)
10014 {
10015 x = SUBREG_REG (x);
10016 if (GET_MODE (x) == mode)
10017 return x;
10018 }
10019
10020 result = gen_lowpart_common (mode, x);
10021 #ifdef CANNOT_CHANGE_MODE_CLASS
10022 if (result != 0
10023 && GET_CODE (result) == SUBREG
10024 && GET_CODE (SUBREG_REG (result)) == REG
10025 && REGNO (SUBREG_REG (result)) >= FIRST_PSEUDO_REGISTER)
10026 bitmap_set_bit (&subregs_of_mode, REGNO (SUBREG_REG (result))
10027 * MAX_MACHINE_MODE
10028 + GET_MODE (result));
10029 #endif
10030
10031 if (result)
10032 return result;
10033
10034 if (GET_CODE (x) == MEM)
10035 {
10036 int offset = 0;
10037
10038 /* Refuse to work on a volatile memory ref or one with a mode-dependent
10039 address. */
10040 if (MEM_VOLATILE_P (x) || mode_dependent_address_p (XEXP (x, 0)))
10041 return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx);
10042
10043 /* If we want to refer to something bigger than the original memref,
10044 generate a perverse subreg instead. That will force a reload
10045 of the original memref X. */
10046 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (mode))
10047 return gen_rtx_SUBREG (mode, x, 0);
10048
10049 if (WORDS_BIG_ENDIAN)
10050 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
10051 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
10052
10053 if (BYTES_BIG_ENDIAN)
10054 {
10055 /* Adjust the address so that the address-after-the-data is
10056 unchanged. */
10057 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
10058 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
10059 }
10060
10061 return adjust_address_nv (x, mode, offset);
10062 }
10063
10064 /* If X is a comparison operator, rewrite it in a new mode. This
10065 probably won't match, but may allow further simplifications. */
10066 else if (GET_RTX_CLASS (GET_CODE (x)) == '<')
10067 return gen_rtx_fmt_ee (GET_CODE (x), mode, XEXP (x, 0), XEXP (x, 1));
10068
10069 /* If we couldn't simplify X any other way, just enclose it in a
10070 SUBREG. Normally, this SUBREG won't match, but some patterns may
10071 include an explicit SUBREG or we may simplify it further in combine. */
10072 else
10073 {
10074 int offset = 0;
10075 rtx res;
10076 enum machine_mode sub_mode = GET_MODE (x);
10077
10078 offset = subreg_lowpart_offset (mode, sub_mode);
10079 if (sub_mode == VOIDmode)
10080 {
10081 sub_mode = int_mode_for_mode (mode);
10082 x = gen_lowpart_common (sub_mode, x);
10083 if (x == 0)
10084 return gen_rtx_CLOBBER (VOIDmode, const0_rtx);
10085 }
10086 res = simplify_gen_subreg (mode, x, sub_mode, offset);
10087 if (res)
10088 return res;
10089 return gen_rtx_CLOBBER (GET_MODE (x), const0_rtx);
10090 }
10091 }
10092
10093 /* These routines make binary and unary operations by first seeing if they
10094 fold; if not, a new expression is allocated. */
10095
10096 static rtx
gen_binary(enum rtx_code code,enum machine_mode mode,rtx op0,rtx op1)10097 gen_binary (enum rtx_code code, enum machine_mode mode, rtx op0, rtx op1)
10098 {
10099 rtx result;
10100 rtx tem;
10101
10102 if (GET_CODE (op0) == CLOBBER)
10103 return op0;
10104 else if (GET_CODE (op1) == CLOBBER)
10105 return op1;
10106
10107 if (GET_RTX_CLASS (code) == 'c'
10108 && swap_commutative_operands_p (op0, op1))
10109 tem = op0, op0 = op1, op1 = tem;
10110
10111 if (GET_RTX_CLASS (code) == '<')
10112 {
10113 enum machine_mode op_mode = GET_MODE (op0);
10114
10115 /* Strip the COMPARE from (REL_OP (compare X Y) 0) to get
10116 just (REL_OP X Y). */
10117 if (GET_CODE (op0) == COMPARE && op1 == const0_rtx)
10118 {
10119 op1 = XEXP (op0, 1);
10120 op0 = XEXP (op0, 0);
10121 op_mode = GET_MODE (op0);
10122 }
10123
10124 if (op_mode == VOIDmode)
10125 op_mode = GET_MODE (op1);
10126 result = simplify_relational_operation (code, op_mode, op0, op1);
10127 }
10128 else
10129 result = simplify_binary_operation (code, mode, op0, op1);
10130
10131 if (result)
10132 return result;
10133
10134 /* Put complex operands first and constants second. */
10135 if (GET_RTX_CLASS (code) == 'c'
10136 && swap_commutative_operands_p (op0, op1))
10137 return gen_rtx_fmt_ee (code, mode, op1, op0);
10138
10139 /* If we are turning off bits already known off in OP0, we need not do
10140 an AND. */
10141 else if (code == AND && GET_CODE (op1) == CONST_INT
10142 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
10143 && (nonzero_bits (op0, mode) & ~INTVAL (op1)) == 0)
10144 return op0;
10145
10146 return gen_rtx_fmt_ee (code, mode, op0, op1);
10147 }
10148
10149 /* Simplify a comparison between *POP0 and *POP1 where CODE is the
10150 comparison code that will be tested.
10151
10152 The result is a possibly different comparison code to use. *POP0 and
10153 *POP1 may be updated.
10154
10155 It is possible that we might detect that a comparison is either always
10156 true or always false. However, we do not perform general constant
10157 folding in combine, so this knowledge isn't useful. Such tautologies
10158 should have been detected earlier. Hence we ignore all such cases. */
10159
10160 static enum rtx_code
simplify_comparison(enum rtx_code code,rtx * pop0,rtx * pop1)10161 simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
10162 {
10163 rtx op0 = *pop0;
10164 rtx op1 = *pop1;
10165 rtx tem, tem1;
10166 int i;
10167 enum machine_mode mode, tmode;
10168
10169 /* Try a few ways of applying the same transformation to both operands. */
10170 while (1)
10171 {
10172 #ifndef WORD_REGISTER_OPERATIONS
10173 /* The test below this one won't handle SIGN_EXTENDs on these machines,
10174 so check specially. */
10175 if (code != GTU && code != GEU && code != LTU && code != LEU
10176 && GET_CODE (op0) == ASHIFTRT && GET_CODE (op1) == ASHIFTRT
10177 && GET_CODE (XEXP (op0, 0)) == ASHIFT
10178 && GET_CODE (XEXP (op1, 0)) == ASHIFT
10179 && GET_CODE (XEXP (XEXP (op0, 0), 0)) == SUBREG
10180 && GET_CODE (XEXP (XEXP (op1, 0), 0)) == SUBREG
10181 && (GET_MODE (SUBREG_REG (XEXP (XEXP (op0, 0), 0)))
10182 == GET_MODE (SUBREG_REG (XEXP (XEXP (op1, 0), 0))))
10183 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10184 && XEXP (op0, 1) == XEXP (op1, 1)
10185 && XEXP (op0, 1) == XEXP (XEXP (op0, 0), 1)
10186 && XEXP (op0, 1) == XEXP (XEXP (op1, 0), 1)
10187 && (INTVAL (XEXP (op0, 1))
10188 == (GET_MODE_BITSIZE (GET_MODE (op0))
10189 - (GET_MODE_BITSIZE
10190 (GET_MODE (SUBREG_REG (XEXP (XEXP (op0, 0), 0))))))))
10191 {
10192 op0 = SUBREG_REG (XEXP (XEXP (op0, 0), 0));
10193 op1 = SUBREG_REG (XEXP (XEXP (op1, 0), 0));
10194 }
10195 #endif
10196
10197 /* If both operands are the same constant shift, see if we can ignore the
10198 shift. We can if the shift is a rotate or if the bits shifted out of
10199 this shift are known to be zero for both inputs and if the type of
10200 comparison is compatible with the shift. */
10201 if (GET_CODE (op0) == GET_CODE (op1)
10202 && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT
10203 && ((GET_CODE (op0) == ROTATE && (code == NE || code == EQ))
10204 || ((GET_CODE (op0) == LSHIFTRT || GET_CODE (op0) == ASHIFT)
10205 && (code != GT && code != LT && code != GE && code != LE))
10206 || (GET_CODE (op0) == ASHIFTRT
10207 && (code != GTU && code != LTU
10208 && code != GEU && code != LEU)))
10209 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10210 && INTVAL (XEXP (op0, 1)) >= 0
10211 && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT
10212 && XEXP (op0, 1) == XEXP (op1, 1))
10213 {
10214 enum machine_mode mode = GET_MODE (op0);
10215 unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode);
10216 int shift_count = INTVAL (XEXP (op0, 1));
10217
10218 if (GET_CODE (op0) == LSHIFTRT || GET_CODE (op0) == ASHIFTRT)
10219 mask &= (mask >> shift_count) << shift_count;
10220 else if (GET_CODE (op0) == ASHIFT)
10221 mask = (mask & (mask << shift_count)) >> shift_count;
10222
10223 if ((nonzero_bits (XEXP (op0, 0), mode) & ~mask) == 0
10224 && (nonzero_bits (XEXP (op1, 0), mode) & ~mask) == 0)
10225 op0 = XEXP (op0, 0), op1 = XEXP (op1, 0);
10226 else
10227 break;
10228 }
10229
10230 /* If both operands are AND's of a paradoxical SUBREG by constant, the
10231 SUBREGs are of the same mode, and, in both cases, the AND would
10232 be redundant if the comparison was done in the narrower mode,
10233 do the comparison in the narrower mode (e.g., we are AND'ing with 1
10234 and the operand's possibly nonzero bits are 0xffffff01; in that case
10235 if we only care about QImode, we don't need the AND). This case
10236 occurs if the output mode of an scc insn is not SImode and
10237 STORE_FLAG_VALUE == 1 (e.g., the 386).
10238
10239 Similarly, check for a case where the AND's are ZERO_EXTEND
10240 operations from some narrower mode even though a SUBREG is not
10241 present. */
10242
10243 else if (GET_CODE (op0) == AND && GET_CODE (op1) == AND
10244 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10245 && GET_CODE (XEXP (op1, 1)) == CONST_INT)
10246 {
10247 rtx inner_op0 = XEXP (op0, 0);
10248 rtx inner_op1 = XEXP (op1, 0);
10249 HOST_WIDE_INT c0 = INTVAL (XEXP (op0, 1));
10250 HOST_WIDE_INT c1 = INTVAL (XEXP (op1, 1));
10251 int changed = 0;
10252
10253 if (GET_CODE (inner_op0) == SUBREG && GET_CODE (inner_op1) == SUBREG
10254 && (GET_MODE_SIZE (GET_MODE (inner_op0))
10255 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (inner_op0))))
10256 && (GET_MODE (SUBREG_REG (inner_op0))
10257 == GET_MODE (SUBREG_REG (inner_op1)))
10258 && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (inner_op0)))
10259 <= HOST_BITS_PER_WIDE_INT)
10260 && (0 == ((~c0) & nonzero_bits (SUBREG_REG (inner_op0),
10261 GET_MODE (SUBREG_REG (inner_op0)))))
10262 && (0 == ((~c1) & nonzero_bits (SUBREG_REG (inner_op1),
10263 GET_MODE (SUBREG_REG (inner_op1))))))
10264 {
10265 op0 = SUBREG_REG (inner_op0);
10266 op1 = SUBREG_REG (inner_op1);
10267
10268 /* The resulting comparison is always unsigned since we masked
10269 off the original sign bit. */
10270 code = unsigned_condition (code);
10271
10272 changed = 1;
10273 }
10274
10275 else if (c0 == c1)
10276 for (tmode = GET_CLASS_NARROWEST_MODE
10277 (GET_MODE_CLASS (GET_MODE (op0)));
10278 tmode != GET_MODE (op0); tmode = GET_MODE_WIDER_MODE (tmode))
10279 if ((unsigned HOST_WIDE_INT) c0 == GET_MODE_MASK (tmode))
10280 {
10281 op0 = gen_lowpart_for_combine (tmode, inner_op0);
10282 op1 = gen_lowpart_for_combine (tmode, inner_op1);
10283 code = unsigned_condition (code);
10284 changed = 1;
10285 break;
10286 }
10287
10288 if (! changed)
10289 break;
10290 }
10291
10292 /* If both operands are NOT, we can strip off the outer operation
10293 and adjust the comparison code for swapped operands; similarly for
10294 NEG, except that this must be an equality comparison. */
10295 else if ((GET_CODE (op0) == NOT && GET_CODE (op1) == NOT)
10296 || (GET_CODE (op0) == NEG && GET_CODE (op1) == NEG
10297 && (code == EQ || code == NE)))
10298 op0 = XEXP (op0, 0), op1 = XEXP (op1, 0), code = swap_condition (code);
10299
10300 else
10301 break;
10302 }
10303
10304 /* If the first operand is a constant, swap the operands and adjust the
10305 comparison code appropriately, but don't do this if the second operand
10306 is already a constant integer. */
10307 if (swap_commutative_operands_p (op0, op1))
10308 {
10309 tem = op0, op0 = op1, op1 = tem;
10310 code = swap_condition (code);
10311 }
10312
10313 /* We now enter a loop during which we will try to simplify the comparison.
10314 For the most part, we only are concerned with comparisons with zero,
10315 but some things may really be comparisons with zero but not start
10316 out looking that way. */
10317
10318 while (GET_CODE (op1) == CONST_INT)
10319 {
10320 enum machine_mode mode = GET_MODE (op0);
10321 unsigned int mode_width = GET_MODE_BITSIZE (mode);
10322 unsigned HOST_WIDE_INT mask = GET_MODE_MASK (mode);
10323 int equality_comparison_p;
10324 int sign_bit_comparison_p;
10325 int unsigned_comparison_p;
10326 HOST_WIDE_INT const_op;
10327
10328 /* We only want to handle integral modes. This catches VOIDmode,
10329 CCmode, and the floating-point modes. An exception is that we
10330 can handle VOIDmode if OP0 is a COMPARE or a comparison
10331 operation. */
10332
10333 if (GET_MODE_CLASS (mode) != MODE_INT
10334 && ! (mode == VOIDmode
10335 && (GET_CODE (op0) == COMPARE
10336 || GET_RTX_CLASS (GET_CODE (op0)) == '<')))
10337 break;
10338
10339 /* Get the constant we are comparing against and turn off all bits
10340 not on in our mode. */
10341 const_op = INTVAL (op1);
10342 if (mode != VOIDmode)
10343 const_op = trunc_int_for_mode (const_op, mode);
10344 op1 = GEN_INT (const_op);
10345
10346 /* If we are comparing against a constant power of two and the value
10347 being compared can only have that single bit nonzero (e.g., it was
10348 `and'ed with that bit), we can replace this with a comparison
10349 with zero. */
10350 if (const_op
10351 && (code == EQ || code == NE || code == GE || code == GEU
10352 || code == LT || code == LTU)
10353 && mode_width <= HOST_BITS_PER_WIDE_INT
10354 && exact_log2 (const_op) >= 0
10355 && nonzero_bits (op0, mode) == (unsigned HOST_WIDE_INT) const_op)
10356 {
10357 code = (code == EQ || code == GE || code == GEU ? NE : EQ);
10358 op1 = const0_rtx, const_op = 0;
10359 }
10360
10361 /* Similarly, if we are comparing a value known to be either -1 or
10362 0 with -1, change it to the opposite comparison against zero. */
10363
10364 if (const_op == -1
10365 && (code == EQ || code == NE || code == GT || code == LE
10366 || code == GEU || code == LTU)
10367 && num_sign_bit_copies (op0, mode) == mode_width)
10368 {
10369 code = (code == EQ || code == LE || code == GEU ? NE : EQ);
10370 op1 = const0_rtx, const_op = 0;
10371 }
10372
10373 /* Do some canonicalizations based on the comparison code. We prefer
10374 comparisons against zero and then prefer equality comparisons.
10375 If we can reduce the size of a constant, we will do that too. */
10376
10377 switch (code)
10378 {
10379 case LT:
10380 /* < C is equivalent to <= (C - 1) */
10381 if (const_op > 0)
10382 {
10383 const_op -= 1;
10384 op1 = GEN_INT (const_op);
10385 code = LE;
10386 /* ... fall through to LE case below. */
10387 }
10388 else
10389 break;
10390
10391 case LE:
10392 /* <= C is equivalent to < (C + 1); we do this for C < 0 */
10393 if (const_op < 0)
10394 {
10395 const_op += 1;
10396 op1 = GEN_INT (const_op);
10397 code = LT;
10398 }
10399
10400 /* If we are doing a <= 0 comparison on a value known to have
10401 a zero sign bit, we can replace this with == 0. */
10402 else if (const_op == 0
10403 && mode_width <= HOST_BITS_PER_WIDE_INT
10404 && (nonzero_bits (op0, mode)
10405 & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0)
10406 code = EQ;
10407 break;
10408
10409 case GE:
10410 /* >= C is equivalent to > (C - 1). */
10411 if (const_op > 0)
10412 {
10413 const_op -= 1;
10414 op1 = GEN_INT (const_op);
10415 code = GT;
10416 /* ... fall through to GT below. */
10417 }
10418 else
10419 break;
10420
10421 case GT:
10422 /* > C is equivalent to >= (C + 1); we do this for C < 0. */
10423 if (const_op < 0)
10424 {
10425 const_op += 1;
10426 op1 = GEN_INT (const_op);
10427 code = GE;
10428 }
10429
10430 /* If we are doing a > 0 comparison on a value known to have
10431 a zero sign bit, we can replace this with != 0. */
10432 else if (const_op == 0
10433 && mode_width <= HOST_BITS_PER_WIDE_INT
10434 && (nonzero_bits (op0, mode)
10435 & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0)
10436 code = NE;
10437 break;
10438
10439 case LTU:
10440 /* < C is equivalent to <= (C - 1). */
10441 if (const_op > 0)
10442 {
10443 const_op -= 1;
10444 op1 = GEN_INT (const_op);
10445 code = LEU;
10446 /* ... fall through ... */
10447 }
10448
10449 /* (unsigned) < 0x80000000 is equivalent to >= 0. */
10450 else if ((mode_width <= HOST_BITS_PER_WIDE_INT)
10451 && (const_op == (HOST_WIDE_INT) 1 << (mode_width - 1)))
10452 {
10453 const_op = 0, op1 = const0_rtx;
10454 code = GE;
10455 break;
10456 }
10457 else
10458 break;
10459
10460 case LEU:
10461 /* unsigned <= 0 is equivalent to == 0 */
10462 if (const_op == 0)
10463 code = EQ;
10464
10465 /* (unsigned) <= 0x7fffffff is equivalent to >= 0. */
10466 else if ((mode_width <= HOST_BITS_PER_WIDE_INT)
10467 && (const_op == ((HOST_WIDE_INT) 1 << (mode_width - 1)) - 1))
10468 {
10469 const_op = 0, op1 = const0_rtx;
10470 code = GE;
10471 }
10472 break;
10473
10474 case GEU:
10475 /* >= C is equivalent to < (C - 1). */
10476 if (const_op > 1)
10477 {
10478 const_op -= 1;
10479 op1 = GEN_INT (const_op);
10480 code = GTU;
10481 /* ... fall through ... */
10482 }
10483
10484 /* (unsigned) >= 0x80000000 is equivalent to < 0. */
10485 else if ((mode_width <= HOST_BITS_PER_WIDE_INT)
10486 && (const_op == (HOST_WIDE_INT) 1 << (mode_width - 1)))
10487 {
10488 const_op = 0, op1 = const0_rtx;
10489 code = LT;
10490 break;
10491 }
10492 else
10493 break;
10494
10495 case GTU:
10496 /* unsigned > 0 is equivalent to != 0 */
10497 if (const_op == 0)
10498 code = NE;
10499
10500 /* (unsigned) > 0x7fffffff is equivalent to < 0. */
10501 else if ((mode_width <= HOST_BITS_PER_WIDE_INT)
10502 && (const_op == ((HOST_WIDE_INT) 1 << (mode_width - 1)) - 1))
10503 {
10504 const_op = 0, op1 = const0_rtx;
10505 code = LT;
10506 }
10507 break;
10508
10509 default:
10510 break;
10511 }
10512
10513 /* Compute some predicates to simplify code below. */
10514
10515 equality_comparison_p = (code == EQ || code == NE);
10516 sign_bit_comparison_p = ((code == LT || code == GE) && const_op == 0);
10517 unsigned_comparison_p = (code == LTU || code == LEU || code == GTU
10518 || code == GEU);
10519
10520 /* If this is a sign bit comparison and we can do arithmetic in
10521 MODE, say that we will only be needing the sign bit of OP0. */
10522 if (sign_bit_comparison_p
10523 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
10524 op0 = force_to_mode (op0, mode,
10525 ((HOST_WIDE_INT) 1
10526 << (GET_MODE_BITSIZE (mode) - 1)),
10527 NULL_RTX, 0);
10528
10529 /* Now try cases based on the opcode of OP0. If none of the cases
10530 does a "continue", we exit this loop immediately after the
10531 switch. */
10532
10533 switch (GET_CODE (op0))
10534 {
10535 case ZERO_EXTRACT:
10536 /* If we are extracting a single bit from a variable position in
10537 a constant that has only a single bit set and are comparing it
10538 with zero, we can convert this into an equality comparison
10539 between the position and the location of the single bit. */
10540 /* Except we can't if SHIFT_COUNT_TRUNCATED is set, since we might
10541 have already reduced the shift count modulo the word size. */
10542 if (!SHIFT_COUNT_TRUNCATED
10543 && GET_CODE (XEXP (op0, 0)) == CONST_INT
10544 && XEXP (op0, 1) == const1_rtx
10545 && equality_comparison_p && const_op == 0
10546 && (i = exact_log2 (INTVAL (XEXP (op0, 0)))) >= 0)
10547 {
10548 if (BITS_BIG_ENDIAN)
10549 {
10550 enum machine_mode new_mode
10551 = mode_for_extraction (EP_extzv, 1);
10552 if (new_mode == MAX_MACHINE_MODE)
10553 i = BITS_PER_WORD - 1 - i;
10554 else
10555 {
10556 mode = new_mode;
10557 i = (GET_MODE_BITSIZE (mode) - 1 - i);
10558 }
10559 }
10560
10561 op0 = XEXP (op0, 2);
10562 op1 = GEN_INT (i);
10563 const_op = i;
10564
10565 /* Result is nonzero iff shift count is equal to I. */
10566 code = reverse_condition (code);
10567 continue;
10568 }
10569
10570 /* ... fall through ... */
10571
10572 case SIGN_EXTRACT:
10573 tem = expand_compound_operation (op0);
10574 if (tem != op0)
10575 {
10576 op0 = tem;
10577 continue;
10578 }
10579 break;
10580
10581 case NOT:
10582 /* If testing for equality, we can take the NOT of the constant. */
10583 if (equality_comparison_p
10584 && (tem = simplify_unary_operation (NOT, mode, op1, mode)) != 0)
10585 {
10586 op0 = XEXP (op0, 0);
10587 op1 = tem;
10588 continue;
10589 }
10590
10591 /* If just looking at the sign bit, reverse the sense of the
10592 comparison. */
10593 if (sign_bit_comparison_p)
10594 {
10595 op0 = XEXP (op0, 0);
10596 code = (code == GE ? LT : GE);
10597 continue;
10598 }
10599 break;
10600
10601 case NEG:
10602 /* If testing for equality, we can take the NEG of the constant. */
10603 if (equality_comparison_p
10604 && (tem = simplify_unary_operation (NEG, mode, op1, mode)) != 0)
10605 {
10606 op0 = XEXP (op0, 0);
10607 op1 = tem;
10608 continue;
10609 }
10610
10611 /* The remaining cases only apply to comparisons with zero. */
10612 if (const_op != 0)
10613 break;
10614
10615 /* When X is ABS or is known positive,
10616 (neg X) is < 0 if and only if X != 0. */
10617
10618 if (sign_bit_comparison_p
10619 && (GET_CODE (XEXP (op0, 0)) == ABS
10620 || (mode_width <= HOST_BITS_PER_WIDE_INT
10621 && (nonzero_bits (XEXP (op0, 0), mode)
10622 & ((HOST_WIDE_INT) 1 << (mode_width - 1))) == 0)))
10623 {
10624 op0 = XEXP (op0, 0);
10625 code = (code == LT ? NE : EQ);
10626 continue;
10627 }
10628
10629 /* If we have NEG of something whose two high-order bits are the
10630 same, we know that "(-a) < 0" is equivalent to "a > 0". */
10631 if (num_sign_bit_copies (op0, mode) >= 2)
10632 {
10633 op0 = XEXP (op0, 0);
10634 code = swap_condition (code);
10635 continue;
10636 }
10637 break;
10638
10639 case ROTATE:
10640 /* If we are testing equality and our count is a constant, we
10641 can perform the inverse operation on our RHS. */
10642 if (equality_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT
10643 && (tem = simplify_binary_operation (ROTATERT, mode,
10644 op1, XEXP (op0, 1))) != 0)
10645 {
10646 op0 = XEXP (op0, 0);
10647 op1 = tem;
10648 continue;
10649 }
10650
10651 /* If we are doing a < 0 or >= 0 comparison, it means we are testing
10652 a particular bit. Convert it to an AND of a constant of that
10653 bit. This will be converted into a ZERO_EXTRACT. */
10654 if (const_op == 0 && sign_bit_comparison_p
10655 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10656 && mode_width <= HOST_BITS_PER_WIDE_INT)
10657 {
10658 op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0),
10659 ((HOST_WIDE_INT) 1
10660 << (mode_width - 1
10661 - INTVAL (XEXP (op0, 1)))));
10662 code = (code == LT ? NE : EQ);
10663 continue;
10664 }
10665
10666 /* Fall through. */
10667
10668 case ABS:
10669 /* ABS is ignorable inside an equality comparison with zero. */
10670 if (const_op == 0 && equality_comparison_p)
10671 {
10672 op0 = XEXP (op0, 0);
10673 continue;
10674 }
10675 break;
10676
10677 case SIGN_EXTEND:
10678 /* Can simplify (compare (zero/sign_extend FOO) CONST)
10679 to (compare FOO CONST) if CONST fits in FOO's mode and we
10680 are either testing inequality or have an unsigned comparison
10681 with ZERO_EXTEND or a signed comparison with SIGN_EXTEND. */
10682 if (! unsigned_comparison_p
10683 && (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0)))
10684 <= HOST_BITS_PER_WIDE_INT)
10685 && ((unsigned HOST_WIDE_INT) const_op
10686 < (((unsigned HOST_WIDE_INT) 1
10687 << (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0))) - 1)))))
10688 {
10689 op0 = XEXP (op0, 0);
10690 continue;
10691 }
10692 break;
10693
10694 case SUBREG:
10695 /* Check for the case where we are comparing A - C1 with C2,
10696 both constants are smaller than 1/2 the maximum positive
10697 value in MODE, and the comparison is equality or unsigned.
10698 In that case, if A is either zero-extended to MODE or has
10699 sufficient sign bits so that the high-order bit in MODE
10700 is a copy of the sign in the inner mode, we can prove that it is
10701 safe to do the operation in the wider mode. This simplifies
10702 many range checks. */
10703
10704 if (mode_width <= HOST_BITS_PER_WIDE_INT
10705 && subreg_lowpart_p (op0)
10706 && GET_CODE (SUBREG_REG (op0)) == PLUS
10707 && GET_CODE (XEXP (SUBREG_REG (op0), 1)) == CONST_INT
10708 && INTVAL (XEXP (SUBREG_REG (op0), 1)) < 0
10709 && (-INTVAL (XEXP (SUBREG_REG (op0), 1))
10710 < (HOST_WIDE_INT) (GET_MODE_MASK (mode) / 2))
10711 && (unsigned HOST_WIDE_INT) const_op < GET_MODE_MASK (mode) / 2
10712 && (0 == (nonzero_bits (XEXP (SUBREG_REG (op0), 0),
10713 GET_MODE (SUBREG_REG (op0)))
10714 & ~GET_MODE_MASK (mode))
10715 || (num_sign_bit_copies (XEXP (SUBREG_REG (op0), 0),
10716 GET_MODE (SUBREG_REG (op0)))
10717 > (unsigned int)
10718 (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0)))
10719 - GET_MODE_BITSIZE (mode)))))
10720 {
10721 op0 = SUBREG_REG (op0);
10722 continue;
10723 }
10724
10725 /* If the inner mode is narrower and we are extracting the low part,
10726 we can treat the SUBREG as if it were a ZERO_EXTEND. */
10727 if (subreg_lowpart_p (op0)
10728 && GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0))) < mode_width)
10729 /* Fall through */ ;
10730 else
10731 break;
10732
10733 /* ... fall through ... */
10734
10735 case ZERO_EXTEND:
10736 if ((unsigned_comparison_p || equality_comparison_p)
10737 && (GET_MODE_BITSIZE (GET_MODE (XEXP (op0, 0)))
10738 <= HOST_BITS_PER_WIDE_INT)
10739 && ((unsigned HOST_WIDE_INT) const_op
10740 < GET_MODE_MASK (GET_MODE (XEXP (op0, 0)))))
10741 {
10742 op0 = XEXP (op0, 0);
10743 continue;
10744 }
10745 break;
10746
10747 case PLUS:
10748 /* (eq (plus X A) B) -> (eq X (minus B A)). We can only do
10749 this for equality comparisons due to pathological cases involving
10750 overflows. */
10751 if (equality_comparison_p
10752 && 0 != (tem = simplify_binary_operation (MINUS, mode,
10753 op1, XEXP (op0, 1))))
10754 {
10755 op0 = XEXP (op0, 0);
10756 op1 = tem;
10757 continue;
10758 }
10759
10760 /* (plus (abs X) (const_int -1)) is < 0 if and only if X == 0. */
10761 if (const_op == 0 && XEXP (op0, 1) == constm1_rtx
10762 && GET_CODE (XEXP (op0, 0)) == ABS && sign_bit_comparison_p)
10763 {
10764 op0 = XEXP (XEXP (op0, 0), 0);
10765 code = (code == LT ? EQ : NE);
10766 continue;
10767 }
10768 break;
10769
10770 case MINUS:
10771 /* We used to optimize signed comparisons against zero, but that
10772 was incorrect. Unsigned comparisons against zero (GTU, LEU)
10773 arrive here as equality comparisons, or (GEU, LTU) are
10774 optimized away. No need to special-case them. */
10775
10776 /* (eq (minus A B) C) -> (eq A (plus B C)) or
10777 (eq B (minus A C)), whichever simplifies. We can only do
10778 this for equality comparisons due to pathological cases involving
10779 overflows. */
10780 if (equality_comparison_p
10781 && 0 != (tem = simplify_binary_operation (PLUS, mode,
10782 XEXP (op0, 1), op1)))
10783 {
10784 op0 = XEXP (op0, 0);
10785 op1 = tem;
10786 continue;
10787 }
10788
10789 if (equality_comparison_p
10790 && 0 != (tem = simplify_binary_operation (MINUS, mode,
10791 XEXP (op0, 0), op1)))
10792 {
10793 op0 = XEXP (op0, 1);
10794 op1 = tem;
10795 continue;
10796 }
10797
10798 /* The sign bit of (minus (ashiftrt X C) X), where C is the number
10799 of bits in X minus 1, is one iff X > 0. */
10800 if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 0)) == ASHIFTRT
10801 && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT
10802 && (unsigned HOST_WIDE_INT) INTVAL (XEXP (XEXP (op0, 0), 1))
10803 == mode_width - 1
10804 && rtx_equal_p (XEXP (XEXP (op0, 0), 0), XEXP (op0, 1)))
10805 {
10806 op0 = XEXP (op0, 1);
10807 code = (code == GE ? LE : GT);
10808 continue;
10809 }
10810 break;
10811
10812 case XOR:
10813 /* (eq (xor A B) C) -> (eq A (xor B C)). This is a simplification
10814 if C is zero or B is a constant. */
10815 if (equality_comparison_p
10816 && 0 != (tem = simplify_binary_operation (XOR, mode,
10817 XEXP (op0, 1), op1)))
10818 {
10819 op0 = XEXP (op0, 0);
10820 op1 = tem;
10821 continue;
10822 }
10823 break;
10824
10825 case EQ: case NE:
10826 case UNEQ: case LTGT:
10827 case LT: case LTU: case UNLT: case LE: case LEU: case UNLE:
10828 case GT: case GTU: case UNGT: case GE: case GEU: case UNGE:
10829 case UNORDERED: case ORDERED:
10830 /* We can't do anything if OP0 is a condition code value, rather
10831 than an actual data value. */
10832 if (const_op != 0
10833 || CC0_P (XEXP (op0, 0))
10834 || GET_MODE_CLASS (GET_MODE (XEXP (op0, 0))) == MODE_CC)
10835 break;
10836
10837 /* Get the two operands being compared. */
10838 if (GET_CODE (XEXP (op0, 0)) == COMPARE)
10839 tem = XEXP (XEXP (op0, 0), 0), tem1 = XEXP (XEXP (op0, 0), 1);
10840 else
10841 tem = XEXP (op0, 0), tem1 = XEXP (op0, 1);
10842
10843 /* Check for the cases where we simply want the result of the
10844 earlier test or the opposite of that result. */
10845 if (code == NE || code == EQ
10846 || (GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT
10847 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
10848 && (STORE_FLAG_VALUE
10849 & (((HOST_WIDE_INT) 1
10850 << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1))))
10851 && (code == LT || code == GE)))
10852 {
10853 enum rtx_code new_code;
10854 if (code == LT || code == NE)
10855 new_code = GET_CODE (op0);
10856 else
10857 new_code = combine_reversed_comparison_code (op0);
10858
10859 if (new_code != UNKNOWN)
10860 {
10861 code = new_code;
10862 op0 = tem;
10863 op1 = tem1;
10864 continue;
10865 }
10866 }
10867 break;
10868
10869 case IOR:
10870 /* The sign bit of (ior (plus X (const_int -1)) X) is nonzero
10871 iff X <= 0. */
10872 if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 0)) == PLUS
10873 && XEXP (XEXP (op0, 0), 1) == constm1_rtx
10874 && rtx_equal_p (XEXP (XEXP (op0, 0), 0), XEXP (op0, 1)))
10875 {
10876 op0 = XEXP (op0, 1);
10877 code = (code == GE ? GT : LE);
10878 continue;
10879 }
10880 break;
10881
10882 case AND:
10883 /* Convert (and (xshift 1 X) Y) to (and (lshiftrt Y X) 1). This
10884 will be converted to a ZERO_EXTRACT later. */
10885 if (const_op == 0 && equality_comparison_p
10886 && GET_CODE (XEXP (op0, 0)) == ASHIFT
10887 && XEXP (XEXP (op0, 0), 0) == const1_rtx)
10888 {
10889 op0 = simplify_and_const_int
10890 (op0, mode, gen_rtx_LSHIFTRT (mode,
10891 XEXP (op0, 1),
10892 XEXP (XEXP (op0, 0), 1)),
10893 (HOST_WIDE_INT) 1);
10894 continue;
10895 }
10896
10897 /* If we are comparing (and (lshiftrt X C1) C2) for equality with
10898 zero and X is a comparison and C1 and C2 describe only bits set
10899 in STORE_FLAG_VALUE, we can compare with X. */
10900 if (const_op == 0 && equality_comparison_p
10901 && mode_width <= HOST_BITS_PER_WIDE_INT
10902 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10903 && GET_CODE (XEXP (op0, 0)) == LSHIFTRT
10904 && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT
10905 && INTVAL (XEXP (XEXP (op0, 0), 1)) >= 0
10906 && INTVAL (XEXP (XEXP (op0, 0), 1)) < HOST_BITS_PER_WIDE_INT)
10907 {
10908 mask = ((INTVAL (XEXP (op0, 1)) & GET_MODE_MASK (mode))
10909 << INTVAL (XEXP (XEXP (op0, 0), 1)));
10910 if ((~STORE_FLAG_VALUE & mask) == 0
10911 && (GET_RTX_CLASS (GET_CODE (XEXP (XEXP (op0, 0), 0))) == '<'
10912 || ((tem = get_last_value (XEXP (XEXP (op0, 0), 0))) != 0
10913 && GET_RTX_CLASS (GET_CODE (tem)) == '<')))
10914 {
10915 op0 = XEXP (XEXP (op0, 0), 0);
10916 continue;
10917 }
10918 }
10919
10920 /* If we are doing an equality comparison of an AND of a bit equal
10921 to the sign bit, replace this with a LT or GE comparison of
10922 the underlying value. */
10923 if (equality_comparison_p
10924 && const_op == 0
10925 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10926 && mode_width <= HOST_BITS_PER_WIDE_INT
10927 && ((INTVAL (XEXP (op0, 1)) & GET_MODE_MASK (mode))
10928 == (unsigned HOST_WIDE_INT) 1 << (mode_width - 1)))
10929 {
10930 op0 = XEXP (op0, 0);
10931 code = (code == EQ ? GE : LT);
10932 continue;
10933 }
10934
10935 /* If this AND operation is really a ZERO_EXTEND from a narrower
10936 mode, the constant fits within that mode, and this is either an
10937 equality or unsigned comparison, try to do this comparison in
10938 the narrower mode. */
10939 if ((equality_comparison_p || unsigned_comparison_p)
10940 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10941 && (i = exact_log2 ((INTVAL (XEXP (op0, 1))
10942 & GET_MODE_MASK (mode))
10943 + 1)) >= 0
10944 && const_op >> i == 0
10945 && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode)
10946 {
10947 op0 = gen_lowpart_for_combine (tmode, XEXP (op0, 0));
10948 continue;
10949 }
10950
10951 /* If this is (and:M1 (subreg:M2 X 0) (const_int C1)) where C1
10952 fits in both M1 and M2 and the SUBREG is either paradoxical
10953 or represents the low part, permute the SUBREG and the AND
10954 and try again. */
10955 if (GET_CODE (XEXP (op0, 0)) == SUBREG)
10956 {
10957 unsigned HOST_WIDE_INT c1;
10958 tmode = GET_MODE (SUBREG_REG (XEXP (op0, 0)));
10959 /* Require an integral mode, to avoid creating something like
10960 (AND:SF ...). */
10961 if (SCALAR_INT_MODE_P (tmode)
10962 /* It is unsafe to commute the AND into the SUBREG if the
10963 SUBREG is paradoxical and WORD_REGISTER_OPERATIONS is
10964 not defined. As originally written the upper bits
10965 have a defined value due to the AND operation.
10966 However, if we commute the AND inside the SUBREG then
10967 they no longer have defined values and the meaning of
10968 the code has been changed. */
10969 && (0
10970 #ifdef WORD_REGISTER_OPERATIONS
10971 || (mode_width > GET_MODE_BITSIZE (tmode)
10972 && mode_width <= BITS_PER_WORD)
10973 #endif
10974 || (mode_width <= GET_MODE_BITSIZE (tmode)
10975 && subreg_lowpart_p (XEXP (op0, 0))))
10976 && GET_CODE (XEXP (op0, 1)) == CONST_INT
10977 && mode_width <= HOST_BITS_PER_WIDE_INT
10978 && GET_MODE_BITSIZE (tmode) <= HOST_BITS_PER_WIDE_INT
10979 && ((c1 = INTVAL (XEXP (op0, 1))) & ~mask) == 0
10980 && (c1 & ~GET_MODE_MASK (tmode)) == 0
10981 && c1 != mask
10982 && c1 != GET_MODE_MASK (tmode))
10983 {
10984 op0 = gen_binary (AND, tmode,
10985 SUBREG_REG (XEXP (op0, 0)),
10986 gen_int_mode (c1, tmode));
10987 op0 = gen_lowpart_for_combine (mode, op0);
10988 continue;
10989 }
10990 }
10991
10992 /* Convert (ne (and (not X) 1) 0) to (eq (and X 1) 0). */
10993 if (const_op == 0 && equality_comparison_p
10994 && XEXP (op0, 1) == const1_rtx
10995 && GET_CODE (XEXP (op0, 0)) == NOT)
10996 {
10997 op0 = simplify_and_const_int
10998 (NULL_RTX, mode, XEXP (XEXP (op0, 0), 0), (HOST_WIDE_INT) 1);
10999 code = (code == NE ? EQ : NE);
11000 continue;
11001 }
11002
11003 /* Convert (ne (and (lshiftrt (not X)) 1) 0) to
11004 (eq (and (lshiftrt X) 1) 0).
11005 Also handle the case where (not X) is expressed using xor. */
11006 if (const_op == 0 && equality_comparison_p
11007 && XEXP (op0, 1) == const1_rtx
11008 && GET_CODE (XEXP (op0, 0)) == LSHIFTRT)
11009 {
11010 rtx shift_op = XEXP (XEXP (op0, 0), 0);
11011 rtx shift_count = XEXP (XEXP (op0, 0), 1);
11012
11013 if (GET_CODE (shift_op) == NOT
11014 || (GET_CODE (shift_op) == XOR
11015 && GET_CODE (XEXP (shift_op, 1)) == CONST_INT
11016 && GET_CODE (shift_count) == CONST_INT
11017 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
11018 && (INTVAL (XEXP (shift_op, 1))
11019 == (HOST_WIDE_INT) 1 << INTVAL (shift_count))))
11020 {
11021 op0 = simplify_and_const_int
11022 (NULL_RTX, mode,
11023 gen_rtx_LSHIFTRT (mode, XEXP (shift_op, 0), shift_count),
11024 (HOST_WIDE_INT) 1);
11025 code = (code == NE ? EQ : NE);
11026 continue;
11027 }
11028 }
11029 break;
11030
11031 case ASHIFT:
11032 /* If we have (compare (ashift FOO N) (const_int C)) and
11033 the high order N bits of FOO (N+1 if an inequality comparison)
11034 are known to be zero, we can do this by comparing FOO with C
11035 shifted right N bits so long as the low-order N bits of C are
11036 zero. */
11037 if (GET_CODE (XEXP (op0, 1)) == CONST_INT
11038 && INTVAL (XEXP (op0, 1)) >= 0
11039 && ((INTVAL (XEXP (op0, 1)) + ! equality_comparison_p)
11040 < HOST_BITS_PER_WIDE_INT)
11041 && ((const_op
11042 & (((HOST_WIDE_INT) 1 << INTVAL (XEXP (op0, 1))) - 1)) == 0)
11043 && mode_width <= HOST_BITS_PER_WIDE_INT
11044 && (nonzero_bits (XEXP (op0, 0), mode)
11045 & ~(mask >> (INTVAL (XEXP (op0, 1))
11046 + ! equality_comparison_p))) == 0)
11047 {
11048 /* We must perform a logical shift, not an arithmetic one,
11049 as we want the top N bits of C to be zero. */
11050 unsigned HOST_WIDE_INT temp = const_op & GET_MODE_MASK (mode);
11051
11052 temp >>= INTVAL (XEXP (op0, 1));
11053 op1 = gen_int_mode (temp, mode);
11054 op0 = XEXP (op0, 0);
11055 continue;
11056 }
11057
11058 /* If we are doing a sign bit comparison, it means we are testing
11059 a particular bit. Convert it to the appropriate AND. */
11060 if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT
11061 && mode_width <= HOST_BITS_PER_WIDE_INT)
11062 {
11063 op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0),
11064 ((HOST_WIDE_INT) 1
11065 << (mode_width - 1
11066 - INTVAL (XEXP (op0, 1)))));
11067 code = (code == LT ? NE : EQ);
11068 continue;
11069 }
11070
11071 /* If this an equality comparison with zero and we are shifting
11072 the low bit to the sign bit, we can convert this to an AND of the
11073 low-order bit. */
11074 if (const_op == 0 && equality_comparison_p
11075 && GET_CODE (XEXP (op0, 1)) == CONST_INT
11076 && (unsigned HOST_WIDE_INT) INTVAL (XEXP (op0, 1))
11077 == mode_width - 1)
11078 {
11079 op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0),
11080 (HOST_WIDE_INT) 1);
11081 continue;
11082 }
11083 break;
11084
11085 case ASHIFTRT:
11086 /* If this is an equality comparison with zero, we can do this
11087 as a logical shift, which might be much simpler. */
11088 if (equality_comparison_p && const_op == 0
11089 && GET_CODE (XEXP (op0, 1)) == CONST_INT)
11090 {
11091 op0 = simplify_shift_const (NULL_RTX, LSHIFTRT, mode,
11092 XEXP (op0, 0),
11093 INTVAL (XEXP (op0, 1)));
11094 continue;
11095 }
11096
11097 /* If OP0 is a sign extension and CODE is not an unsigned comparison,
11098 do the comparison in a narrower mode. */
11099 if (! unsigned_comparison_p
11100 && GET_CODE (XEXP (op0, 1)) == CONST_INT
11101 && GET_CODE (XEXP (op0, 0)) == ASHIFT
11102 && XEXP (op0, 1) == XEXP (XEXP (op0, 0), 1)
11103 && (tmode = mode_for_size (mode_width - INTVAL (XEXP (op0, 1)),
11104 MODE_INT, 1)) != BLKmode
11105 && (((unsigned HOST_WIDE_INT) const_op
11106 + (GET_MODE_MASK (tmode) >> 1) + 1)
11107 <= GET_MODE_MASK (tmode)))
11108 {
11109 op0 = gen_lowpart_for_combine (tmode, XEXP (XEXP (op0, 0), 0));
11110 continue;
11111 }
11112
11113 /* Likewise if OP0 is a PLUS of a sign extension with a
11114 constant, which is usually represented with the PLUS
11115 between the shifts. */
11116 if (! unsigned_comparison_p
11117 && GET_CODE (XEXP (op0, 1)) == CONST_INT
11118 && GET_CODE (XEXP (op0, 0)) == PLUS
11119 && GET_CODE (XEXP (XEXP (op0, 0), 1)) == CONST_INT
11120 && GET_CODE (XEXP (XEXP (op0, 0), 0)) == ASHIFT
11121 && XEXP (op0, 1) == XEXP (XEXP (XEXP (op0, 0), 0), 1)
11122 && (tmode = mode_for_size (mode_width - INTVAL (XEXP (op0, 1)),
11123 MODE_INT, 1)) != BLKmode
11124 && (((unsigned HOST_WIDE_INT) const_op
11125 + (GET_MODE_MASK (tmode) >> 1) + 1)
11126 <= GET_MODE_MASK (tmode)))
11127 {
11128 rtx inner = XEXP (XEXP (XEXP (op0, 0), 0), 0);
11129 rtx add_const = XEXP (XEXP (op0, 0), 1);
11130 rtx new_const = gen_binary (ASHIFTRT, GET_MODE (op0), add_const,
11131 XEXP (op0, 1));
11132
11133 op0 = gen_binary (PLUS, tmode,
11134 gen_lowpart_for_combine (tmode, inner),
11135 new_const);
11136 continue;
11137 }
11138
11139 /* ... fall through ... */
11140 case LSHIFTRT:
11141 /* If we have (compare (xshiftrt FOO N) (const_int C)) and
11142 the low order N bits of FOO are known to be zero, we can do this
11143 by comparing FOO with C shifted left N bits so long as no
11144 overflow occurs. */
11145 if (GET_CODE (XEXP (op0, 1)) == CONST_INT
11146 && INTVAL (XEXP (op0, 1)) >= 0
11147 && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT
11148 && mode_width <= HOST_BITS_PER_WIDE_INT
11149 && (nonzero_bits (XEXP (op0, 0), mode)
11150 & (((HOST_WIDE_INT) 1 << INTVAL (XEXP (op0, 1))) - 1)) == 0
11151 && (((unsigned HOST_WIDE_INT) const_op
11152 + (GET_CODE (op0) != LSHIFTRT
11153 ? ((GET_MODE_MASK (mode) >> INTVAL (XEXP (op0, 1)) >> 1)
11154 + 1)
11155 : 0))
11156 <= GET_MODE_MASK (mode) >> INTVAL (XEXP (op0, 1))))
11157 {
11158 /* If the shift was logical, then we must make the condition
11159 unsigned. */
11160 if (GET_CODE (op0) == LSHIFTRT)
11161 code = unsigned_condition (code);
11162
11163 const_op <<= INTVAL (XEXP (op0, 1));
11164 op1 = GEN_INT (const_op);
11165 op0 = XEXP (op0, 0);
11166 continue;
11167 }
11168
11169 /* If we are using this shift to extract just the sign bit, we
11170 can replace this with an LT or GE comparison. */
11171 if (const_op == 0
11172 && (equality_comparison_p || sign_bit_comparison_p)
11173 && GET_CODE (XEXP (op0, 1)) == CONST_INT
11174 && (unsigned HOST_WIDE_INT) INTVAL (XEXP (op0, 1))
11175 == mode_width - 1)
11176 {
11177 op0 = XEXP (op0, 0);
11178 code = (code == NE || code == GT ? LT : GE);
11179 continue;
11180 }
11181 break;
11182
11183 default:
11184 break;
11185 }
11186
11187 break;
11188 }
11189
11190 /* Now make any compound operations involved in this comparison. Then,
11191 check for an outmost SUBREG on OP0 that is not doing anything or is
11192 paradoxical. The latter transformation must only be performed when
11193 it is known that the "extra" bits will be the same in op0 and op1 or
11194 that they don't matter. There are three cases to consider:
11195
11196 1. SUBREG_REG (op0) is a register. In this case the bits are don't
11197 care bits and we can assume they have any convenient value. So
11198 making the transformation is safe.
11199
11200 2. SUBREG_REG (op0) is a memory and LOAD_EXTEND_OP is not defined.
11201 In this case the upper bits of op0 are undefined. We should not make
11202 the simplification in that case as we do not know the contents of
11203 those bits.
11204
11205 3. SUBREG_REG (op0) is a memory and LOAD_EXTEND_OP is defined and not
11206 NIL. In that case we know those bits are zeros or ones. We must
11207 also be sure that they are the same as the upper bits of op1.
11208
11209 We can never remove a SUBREG for a non-equality comparison because
11210 the sign bit is in a different place in the underlying object. */
11211
11212 op0 = make_compound_operation (op0, op1 == const0_rtx ? COMPARE : SET);
11213 op1 = make_compound_operation (op1, SET);
11214
11215 if (GET_CODE (op0) == SUBREG && subreg_lowpart_p (op0)
11216 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
11217 && GET_MODE_CLASS (GET_MODE (SUBREG_REG (op0))) == MODE_INT
11218 && (code == NE || code == EQ))
11219 {
11220 if (GET_MODE_SIZE (GET_MODE (op0))
11221 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0))))
11222 {
11223 /* For paradoxical subregs, allow case 1 as above. Case 3 isn't
11224 implemented. */
11225 if (GET_CODE (SUBREG_REG (op0)) == REG)
11226 {
11227 op0 = SUBREG_REG (op0);
11228 op1 = gen_lowpart_for_combine (GET_MODE (op0), op1);
11229 }
11230 }
11231 else if ((GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0)))
11232 <= HOST_BITS_PER_WIDE_INT)
11233 && (nonzero_bits (SUBREG_REG (op0),
11234 GET_MODE (SUBREG_REG (op0)))
11235 & ~GET_MODE_MASK (GET_MODE (op0))) == 0)
11236 {
11237 tem = gen_lowpart_for_combine (GET_MODE (SUBREG_REG (op0)), op1);
11238
11239 if ((nonzero_bits (tem, GET_MODE (SUBREG_REG (op0)))
11240 & ~GET_MODE_MASK (GET_MODE (op0))) == 0)
11241 op0 = SUBREG_REG (op0), op1 = tem;
11242 }
11243 }
11244
11245 /* We now do the opposite procedure: Some machines don't have compare
11246 insns in all modes. If OP0's mode is an integer mode smaller than a
11247 word and we can't do a compare in that mode, see if there is a larger
11248 mode for which we can do the compare. There are a number of cases in
11249 which we can use the wider mode. */
11250
11251 mode = GET_MODE (op0);
11252 if (mode != VOIDmode && GET_MODE_CLASS (mode) == MODE_INT
11253 && GET_MODE_SIZE (mode) < UNITS_PER_WORD
11254 && ! have_insn_for (COMPARE, mode))
11255 for (tmode = GET_MODE_WIDER_MODE (mode);
11256 (tmode != VOIDmode
11257 && GET_MODE_BITSIZE (tmode) <= HOST_BITS_PER_WIDE_INT);
11258 tmode = GET_MODE_WIDER_MODE (tmode))
11259 if (have_insn_for (COMPARE, tmode))
11260 {
11261 int zero_extended;
11262
11263 /* If the only nonzero bits in OP0 and OP1 are those in the
11264 narrower mode and this is an equality or unsigned comparison,
11265 we can use the wider mode. Similarly for sign-extended
11266 values, in which case it is true for all comparisons. */
11267 zero_extended = ((code == EQ || code == NE
11268 || code == GEU || code == GTU
11269 || code == LEU || code == LTU)
11270 && (nonzero_bits (op0, tmode)
11271 & ~GET_MODE_MASK (mode)) == 0
11272 && ((GET_CODE (op1) == CONST_INT
11273 || (nonzero_bits (op1, tmode)
11274 & ~GET_MODE_MASK (mode)) == 0)));
11275
11276 if (zero_extended
11277 || ((num_sign_bit_copies (op0, tmode)
11278 > (unsigned int) (GET_MODE_BITSIZE (tmode)
11279 - GET_MODE_BITSIZE (mode)))
11280 && (num_sign_bit_copies (op1, tmode)
11281 > (unsigned int) (GET_MODE_BITSIZE (tmode)
11282 - GET_MODE_BITSIZE (mode)))))
11283 {
11284 /* If OP0 is an AND and we don't have an AND in MODE either,
11285 make a new AND in the proper mode. */
11286 if (GET_CODE (op0) == AND
11287 && !have_insn_for (AND, mode))
11288 op0 = gen_binary (AND, tmode,
11289 gen_lowpart_for_combine (tmode,
11290 XEXP (op0, 0)),
11291 gen_lowpart_for_combine (tmode,
11292 XEXP (op0, 1)));
11293
11294 op0 = gen_lowpart_for_combine (tmode, op0);
11295 if (zero_extended && GET_CODE (op1) == CONST_INT)
11296 op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (mode));
11297 op1 = gen_lowpart_for_combine (tmode, op1);
11298 break;
11299 }
11300
11301 /* If this is a test for negative, we can make an explicit
11302 test of the sign bit. */
11303
11304 if (op1 == const0_rtx && (code == LT || code == GE)
11305 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
11306 {
11307 op0 = gen_binary (AND, tmode,
11308 gen_lowpart_for_combine (tmode, op0),
11309 GEN_INT ((HOST_WIDE_INT) 1
11310 << (GET_MODE_BITSIZE (mode) - 1)));
11311 code = (code == LT) ? NE : EQ;
11312 break;
11313 }
11314 }
11315
11316 #ifdef CANONICALIZE_COMPARISON
11317 /* If this machine only supports a subset of valid comparisons, see if we
11318 can convert an unsupported one into a supported one. */
11319 CANONICALIZE_COMPARISON (code, op0, op1);
11320 #endif
11321
11322 *pop0 = op0;
11323 *pop1 = op1;
11324
11325 return code;
11326 }
11327
11328 /* Like jump.c' reversed_comparison_code, but use combine infrastructure for
11329 searching backward. */
11330 static enum rtx_code
combine_reversed_comparison_code(rtx exp)11331 combine_reversed_comparison_code (rtx exp)
11332 {
11333 enum rtx_code code1 = reversed_comparison_code (exp, NULL);
11334 rtx x;
11335
11336 if (code1 != UNKNOWN
11337 || GET_MODE_CLASS (GET_MODE (XEXP (exp, 0))) != MODE_CC)
11338 return code1;
11339 /* Otherwise try and find where the condition codes were last set and
11340 use that. */
11341 x = get_last_value (XEXP (exp, 0));
11342 if (!x || GET_CODE (x) != COMPARE)
11343 return UNKNOWN;
11344 return reversed_comparison_code_parts (GET_CODE (exp),
11345 XEXP (x, 0), XEXP (x, 1), NULL);
11346 }
11347
11348 /* Return comparison with reversed code of EXP and operands OP0 and OP1.
11349 Return NULL_RTX in case we fail to do the reversal. */
11350 static rtx
reversed_comparison(rtx exp,enum machine_mode mode,rtx op0,rtx op1)11351 reversed_comparison (rtx exp, enum machine_mode mode, rtx op0, rtx op1)
11352 {
11353 enum rtx_code reversed_code = combine_reversed_comparison_code (exp);
11354 if (reversed_code == UNKNOWN)
11355 return NULL_RTX;
11356 else
11357 return gen_binary (reversed_code, mode, op0, op1);
11358 }
11359
11360 /* Utility function for following routine. Called when X is part of a value
11361 being stored into reg_last_set_value. Sets reg_last_set_table_tick
11362 for each register mentioned. Similar to mention_regs in cse.c */
11363
11364 static void
update_table_tick(rtx x)11365 update_table_tick (rtx x)
11366 {
11367 enum rtx_code code = GET_CODE (x);
11368 const char *fmt = GET_RTX_FORMAT (code);
11369 int i;
11370
11371 if (code == REG)
11372 {
11373 unsigned int regno = REGNO (x);
11374 unsigned int endregno
11375 = regno + (regno < FIRST_PSEUDO_REGISTER
11376 ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);
11377 unsigned int r;
11378
11379 for (r = regno; r < endregno; r++)
11380 reg_last_set_table_tick[r] = label_tick;
11381
11382 return;
11383 }
11384
11385 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
11386 /* Note that we can't have an "E" in values stored; see
11387 get_last_value_validate. */
11388 if (fmt[i] == 'e')
11389 {
11390 /* Check for identical subexpressions. If x contains
11391 identical subexpression we only have to traverse one of
11392 them. */
11393 if (i == 0
11394 && (GET_RTX_CLASS (code) == '2'
11395 || GET_RTX_CLASS (code) == 'c'))
11396 {
11397 /* Note that at this point x1 has already been
11398 processed. */
11399 rtx x0 = XEXP (x, 0);
11400 rtx x1 = XEXP (x, 1);
11401
11402 /* If x0 and x1 are identical then there is no need to
11403 process x0. */
11404 if (x0 == x1)
11405 break;
11406
11407 /* If x0 is identical to a subexpression of x1 then while
11408 processing x1, x0 has already been processed. Thus we
11409 are done with x. */
11410 if ((GET_RTX_CLASS (GET_CODE (x1)) == '2'
11411 || GET_RTX_CLASS (GET_CODE (x1)) == 'c')
11412 && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1)))
11413 break;
11414
11415 /* If x1 is identical to a subexpression of x0 then we
11416 still have to process the rest of x0. */
11417 if ((GET_RTX_CLASS (GET_CODE (x0)) == '2'
11418 || GET_RTX_CLASS (GET_CODE (x0)) == 'c')
11419 && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1)))
11420 {
11421 update_table_tick (XEXP (x0, x1 == XEXP (x0, 0) ? 1 : 0));
11422 break;
11423 }
11424 }
11425
11426 update_table_tick (XEXP (x, i));
11427 }
11428 }
11429
11430 /* Record that REG is set to VALUE in insn INSN. If VALUE is zero, we
11431 are saying that the register is clobbered and we no longer know its
11432 value. If INSN is zero, don't update reg_last_set; this is only permitted
11433 with VALUE also zero and is used to invalidate the register. */
11434
11435 static void
record_value_for_reg(rtx reg,rtx insn,rtx value)11436 record_value_for_reg (rtx reg, rtx insn, rtx value)
11437 {
11438 unsigned int regno = REGNO (reg);
11439 unsigned int endregno
11440 = regno + (regno < FIRST_PSEUDO_REGISTER
11441 ? HARD_REGNO_NREGS (regno, GET_MODE (reg)) : 1);
11442 unsigned int i;
11443
11444 /* If VALUE contains REG and we have a previous value for REG, substitute
11445 the previous value. */
11446 if (value && insn && reg_overlap_mentioned_p (reg, value))
11447 {
11448 rtx tem;
11449
11450 /* Set things up so get_last_value is allowed to see anything set up to
11451 our insn. */
11452 subst_low_cuid = INSN_CUID (insn);
11453 tem = get_last_value (reg);
11454
11455 /* If TEM is simply a binary operation with two CLOBBERs as operands,
11456 it isn't going to be useful and will take a lot of time to process,
11457 so just use the CLOBBER. */
11458
11459 if (tem)
11460 {
11461 if ((GET_RTX_CLASS (GET_CODE (tem)) == '2'
11462 || GET_RTX_CLASS (GET_CODE (tem)) == 'c')
11463 && GET_CODE (XEXP (tem, 0)) == CLOBBER
11464 && GET_CODE (XEXP (tem, 1)) == CLOBBER)
11465 tem = XEXP (tem, 0);
11466
11467 value = replace_rtx (copy_rtx (value), reg, tem);
11468 }
11469 }
11470
11471 /* For each register modified, show we don't know its value, that
11472 we don't know about its bitwise content, that its value has been
11473 updated, and that we don't know the location of the death of the
11474 register. */
11475 for (i = regno; i < endregno; i++)
11476 {
11477 if (insn)
11478 reg_last_set[i] = insn;
11479
11480 reg_last_set_value[i] = 0;
11481 reg_last_set_mode[i] = 0;
11482 reg_last_set_nonzero_bits[i] = 0;
11483 reg_last_set_sign_bit_copies[i] = 0;
11484 reg_last_death[i] = 0;
11485 }
11486
11487 /* Mark registers that are being referenced in this value. */
11488 if (value)
11489 update_table_tick (value);
11490
11491 /* Now update the status of each register being set.
11492 If someone is using this register in this block, set this register
11493 to invalid since we will get confused between the two lives in this
11494 basic block. This makes using this register always invalid. In cse, we
11495 scan the table to invalidate all entries using this register, but this
11496 is too much work for us. */
11497
11498 for (i = regno; i < endregno; i++)
11499 {
11500 reg_last_set_label[i] = label_tick;
11501 if (value && reg_last_set_table_tick[i] == label_tick)
11502 reg_last_set_invalid[i] = 1;
11503 else
11504 reg_last_set_invalid[i] = 0;
11505 }
11506
11507 /* The value being assigned might refer to X (like in "x++;"). In that
11508 case, we must replace it with (clobber (const_int 0)) to prevent
11509 infinite loops. */
11510 if (value && ! get_last_value_validate (&value, insn,
11511 reg_last_set_label[regno], 0))
11512 {
11513 value = copy_rtx (value);
11514 if (! get_last_value_validate (&value, insn,
11515 reg_last_set_label[regno], 1))
11516 value = 0;
11517 }
11518
11519 /* For the main register being modified, update the value, the mode, the
11520 nonzero bits, and the number of sign bit copies. */
11521
11522 reg_last_set_value[regno] = value;
11523
11524 if (value)
11525 {
11526 enum machine_mode mode = GET_MODE (reg);
11527 subst_low_cuid = INSN_CUID (insn);
11528 reg_last_set_mode[regno] = mode;
11529 if (GET_MODE_CLASS (mode) == MODE_INT
11530 && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
11531 mode = nonzero_bits_mode;
11532 reg_last_set_nonzero_bits[regno] = nonzero_bits (value, mode);
11533 reg_last_set_sign_bit_copies[regno]
11534 = num_sign_bit_copies (value, GET_MODE (reg));
11535 }
11536 }
11537
11538 /* Called via note_stores from record_dead_and_set_regs to handle one
11539 SET or CLOBBER in an insn. DATA is the instruction in which the
11540 set is occurring. */
11541
11542 static void
record_dead_and_set_regs_1(rtx dest,rtx setter,void * data)11543 record_dead_and_set_regs_1 (rtx dest, rtx setter, void *data)
11544 {
11545 rtx record_dead_insn = (rtx) data;
11546
11547 if (GET_CODE (dest) == SUBREG)
11548 dest = SUBREG_REG (dest);
11549
11550 if (GET_CODE (dest) == REG)
11551 {
11552 /* If we are setting the whole register, we know its value. Otherwise
11553 show that we don't know the value. We can handle SUBREG in
11554 some cases. */
11555 if (GET_CODE (setter) == SET && dest == SET_DEST (setter))
11556 record_value_for_reg (dest, record_dead_insn, SET_SRC (setter));
11557 else if (GET_CODE (setter) == SET
11558 && GET_CODE (SET_DEST (setter)) == SUBREG
11559 && SUBREG_REG (SET_DEST (setter)) == dest
11560 && GET_MODE_BITSIZE (GET_MODE (dest)) <= BITS_PER_WORD
11561 && subreg_lowpart_p (SET_DEST (setter)))
11562 record_value_for_reg (dest, record_dead_insn,
11563 gen_lowpart_for_combine (GET_MODE (dest),
11564 SET_SRC (setter)));
11565 else
11566 record_value_for_reg (dest, record_dead_insn, NULL_RTX);
11567 }
11568 else if (GET_CODE (dest) == MEM
11569 /* Ignore pushes, they clobber nothing. */
11570 && ! push_operand (dest, GET_MODE (dest)))
11571 mem_last_set = INSN_CUID (record_dead_insn);
11572 }
11573
11574 /* Update the records of when each REG was most recently set or killed
11575 for the things done by INSN. This is the last thing done in processing
11576 INSN in the combiner loop.
11577
11578 We update reg_last_set, reg_last_set_value, reg_last_set_mode,
11579 reg_last_set_nonzero_bits, reg_last_set_sign_bit_copies, reg_last_death,
11580 and also the similar information mem_last_set (which insn most recently
11581 modified memory) and last_call_cuid (which insn was the most recent
11582 subroutine call). */
11583
11584 static void
record_dead_and_set_regs(rtx insn)11585 record_dead_and_set_regs (rtx insn)
11586 {
11587 rtx link;
11588 unsigned int i;
11589
11590 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
11591 {
11592 if (REG_NOTE_KIND (link) == REG_DEAD
11593 && GET_CODE (XEXP (link, 0)) == REG)
11594 {
11595 unsigned int regno = REGNO (XEXP (link, 0));
11596 unsigned int endregno
11597 = regno + (regno < FIRST_PSEUDO_REGISTER
11598 ? HARD_REGNO_NREGS (regno, GET_MODE (XEXP (link, 0)))
11599 : 1);
11600
11601 for (i = regno; i < endregno; i++)
11602 reg_last_death[i] = insn;
11603 }
11604 else if (REG_NOTE_KIND (link) == REG_INC)
11605 record_value_for_reg (XEXP (link, 0), insn, NULL_RTX);
11606 }
11607
11608 if (GET_CODE (insn) == CALL_INSN)
11609 {
11610 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
11611 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
11612 {
11613 reg_last_set_value[i] = 0;
11614 reg_last_set_mode[i] = 0;
11615 reg_last_set_nonzero_bits[i] = 0;
11616 reg_last_set_sign_bit_copies[i] = 0;
11617 reg_last_death[i] = 0;
11618 }
11619
11620 last_call_cuid = mem_last_set = INSN_CUID (insn);
11621
11622 /* Don't bother recording what this insn does. It might set the
11623 return value register, but we can't combine into a call
11624 pattern anyway, so there's no point trying (and it may cause
11625 a crash, if e.g. we wind up asking for last_set_value of a
11626 SUBREG of the return value register). */
11627 return;
11628 }
11629
11630 note_stores (PATTERN (insn), record_dead_and_set_regs_1, insn);
11631 }
11632
11633 /* If a SUBREG has the promoted bit set, it is in fact a property of the
11634 register present in the SUBREG, so for each such SUBREG go back and
11635 adjust nonzero and sign bit information of the registers that are
11636 known to have some zero/sign bits set.
11637
11638 This is needed because when combine blows the SUBREGs away, the
11639 information on zero/sign bits is lost and further combines can be
11640 missed because of that. */
11641
11642 static void
record_promoted_value(rtx insn,rtx subreg)11643 record_promoted_value (rtx insn, rtx subreg)
11644 {
11645 rtx links, set;
11646 unsigned int regno = REGNO (SUBREG_REG (subreg));
11647 enum machine_mode mode = GET_MODE (subreg);
11648
11649 if (GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT)
11650 return;
11651
11652 for (links = LOG_LINKS (insn); links;)
11653 {
11654 insn = XEXP (links, 0);
11655 set = single_set (insn);
11656
11657 if (! set || GET_CODE (SET_DEST (set)) != REG
11658 || REGNO (SET_DEST (set)) != regno
11659 || GET_MODE (SET_DEST (set)) != GET_MODE (SUBREG_REG (subreg)))
11660 {
11661 links = XEXP (links, 1);
11662 continue;
11663 }
11664
11665 if (reg_last_set[regno] == insn)
11666 {
11667 if (SUBREG_PROMOTED_UNSIGNED_P (subreg) > 0)
11668 reg_last_set_nonzero_bits[regno] &= GET_MODE_MASK (mode);
11669 }
11670
11671 if (GET_CODE (SET_SRC (set)) == REG)
11672 {
11673 regno = REGNO (SET_SRC (set));
11674 links = LOG_LINKS (insn);
11675 }
11676 else
11677 break;
11678 }
11679 }
11680
11681 /* Scan X for promoted SUBREGs. For each one found,
11682 note what it implies to the registers used in it. */
11683
11684 static void
check_promoted_subreg(rtx insn,rtx x)11685 check_promoted_subreg (rtx insn, rtx x)
11686 {
11687 if (GET_CODE (x) == SUBREG && SUBREG_PROMOTED_VAR_P (x)
11688 && GET_CODE (SUBREG_REG (x)) == REG)
11689 record_promoted_value (insn, x);
11690 else
11691 {
11692 const char *format = GET_RTX_FORMAT (GET_CODE (x));
11693 int i, j;
11694
11695 for (i = 0; i < GET_RTX_LENGTH (GET_CODE (x)); i++)
11696 switch (format[i])
11697 {
11698 case 'e':
11699 check_promoted_subreg (insn, XEXP (x, i));
11700 break;
11701 case 'V':
11702 case 'E':
11703 if (XVEC (x, i) != 0)
11704 for (j = 0; j < XVECLEN (x, i); j++)
11705 check_promoted_subreg (insn, XVECEXP (x, i, j));
11706 break;
11707 }
11708 }
11709 }
11710
11711 /* Utility routine for the following function. Verify that all the registers
11712 mentioned in *LOC are valid when *LOC was part of a value set when
11713 label_tick == TICK. Return 0 if some are not.
11714
11715 If REPLACE is nonzero, replace the invalid reference with
11716 (clobber (const_int 0)) and return 1. This replacement is useful because
11717 we often can get useful information about the form of a value (e.g., if
11718 it was produced by a shift that always produces -1 or 0) even though
11719 we don't know exactly what registers it was produced from. */
11720
11721 static int
get_last_value_validate(rtx * loc,rtx insn,int tick,int replace)11722 get_last_value_validate (rtx *loc, rtx insn, int tick, int replace)
11723 {
11724 rtx x = *loc;
11725 const char *fmt = GET_RTX_FORMAT (GET_CODE (x));
11726 int len = GET_RTX_LENGTH (GET_CODE (x));
11727 int i;
11728
11729 if (GET_CODE (x) == REG)
11730 {
11731 unsigned int regno = REGNO (x);
11732 unsigned int endregno
11733 = regno + (regno < FIRST_PSEUDO_REGISTER
11734 ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);
11735 unsigned int j;
11736
11737 for (j = regno; j < endregno; j++)
11738 if (reg_last_set_invalid[j]
11739 /* If this is a pseudo-register that was only set once and not
11740 live at the beginning of the function, it is always valid. */
11741 || (! (regno >= FIRST_PSEUDO_REGISTER
11742 && REG_N_SETS (regno) == 1
11743 && (! REGNO_REG_SET_P
11744 (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, regno)))
11745 && reg_last_set_label[j] > tick))
11746 {
11747 if (replace)
11748 *loc = gen_rtx_CLOBBER (GET_MODE (x), const0_rtx);
11749 return replace;
11750 }
11751
11752 return 1;
11753 }
11754 /* If this is a memory reference, make sure that there were
11755 no stores after it that might have clobbered the value. We don't
11756 have alias info, so we assume any store invalidates it. */
11757 else if (GET_CODE (x) == MEM && ! RTX_UNCHANGING_P (x)
11758 && INSN_CUID (insn) <= mem_last_set)
11759 {
11760 if (replace)
11761 *loc = gen_rtx_CLOBBER (GET_MODE (x), const0_rtx);
11762 return replace;
11763 }
11764
11765 for (i = 0; i < len; i++)
11766 {
11767 if (fmt[i] == 'e')
11768 {
11769 /* Check for identical subexpressions. If x contains
11770 identical subexpression we only have to traverse one of
11771 them. */
11772 if (i == 1
11773 && (GET_RTX_CLASS (GET_CODE (x)) == '2'
11774 || GET_RTX_CLASS (GET_CODE (x)) == 'c'))
11775 {
11776 /* Note that at this point x0 has already been checked
11777 and found valid. */
11778 rtx x0 = XEXP (x, 0);
11779 rtx x1 = XEXP (x, 1);
11780
11781 /* If x0 and x1 are identical then x is also valid. */
11782 if (x0 == x1)
11783 return 1;
11784
11785 /* If x1 is identical to a subexpression of x0 then
11786 while checking x0, x1 has already been checked. Thus
11787 it is valid and so as x. */
11788 if ((GET_RTX_CLASS (GET_CODE (x0)) == '2'
11789 || GET_RTX_CLASS (GET_CODE (x0)) == 'c')
11790 && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1)))
11791 return 1;
11792
11793 /* If x0 is identical to a subexpression of x1 then x is
11794 valid iff the rest of x1 is valid. */
11795 if ((GET_RTX_CLASS (GET_CODE (x1)) == '2'
11796 || GET_RTX_CLASS (GET_CODE (x1)) == 'c')
11797 && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1)))
11798 return
11799 get_last_value_validate (&XEXP (x1,
11800 x0 == XEXP (x1, 0) ? 1 : 0),
11801 insn, tick, replace);
11802 }
11803
11804 if (get_last_value_validate (&XEXP (x, i), insn, tick,
11805 replace) == 0)
11806 return 0;
11807 }
11808 /* Don't bother with these. They shouldn't occur anyway. */
11809 else if (fmt[i] == 'E')
11810 return 0;
11811 }
11812
11813 /* If we haven't found a reason for it to be invalid, it is valid. */
11814 return 1;
11815 }
11816
11817 /* Get the last value assigned to X, if known. Some registers
11818 in the value may be replaced with (clobber (const_int 0)) if their value
11819 is known longer known reliably. */
11820
11821 static rtx
get_last_value(rtx x)11822 get_last_value (rtx x)
11823 {
11824 unsigned int regno;
11825 rtx value;
11826
11827 /* If this is a non-paradoxical SUBREG, get the value of its operand and
11828 then convert it to the desired mode. If this is a paradoxical SUBREG,
11829 we cannot predict what values the "extra" bits might have. */
11830 if (GET_CODE (x) == SUBREG
11831 && subreg_lowpart_p (x)
11832 && (GET_MODE_SIZE (GET_MODE (x))
11833 <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
11834 && (value = get_last_value (SUBREG_REG (x))) != 0)
11835 return gen_lowpart_for_combine (GET_MODE (x), value);
11836
11837 if (GET_CODE (x) != REG)
11838 return 0;
11839
11840 regno = REGNO (x);
11841 value = reg_last_set_value[regno];
11842
11843 /* If we don't have a value, or if it isn't for this basic block and
11844 it's either a hard register, set more than once, or it's a live
11845 at the beginning of the function, return 0.
11846
11847 Because if it's not live at the beginning of the function then the reg
11848 is always set before being used (is never used without being set).
11849 And, if it's set only once, and it's always set before use, then all
11850 uses must have the same last value, even if it's not from this basic
11851 block. */
11852
11853 if (value == 0
11854 || (reg_last_set_label[regno] != label_tick
11855 && (regno < FIRST_PSEUDO_REGISTER
11856 || REG_N_SETS (regno) != 1
11857 || (REGNO_REG_SET_P
11858 (ENTRY_BLOCK_PTR->next_bb->global_live_at_start, regno)))))
11859 return 0;
11860
11861 /* If the value was set in a later insn than the ones we are processing,
11862 we can't use it even if the register was only set once. */
11863 if (INSN_CUID (reg_last_set[regno]) >= subst_low_cuid)
11864 return 0;
11865
11866 /* If the value has all its registers valid, return it. */
11867 if (get_last_value_validate (&value, reg_last_set[regno],
11868 reg_last_set_label[regno], 0))
11869 return value;
11870
11871 /* Otherwise, make a copy and replace any invalid register with
11872 (clobber (const_int 0)). If that fails for some reason, return 0. */
11873
11874 value = copy_rtx (value);
11875 if (get_last_value_validate (&value, reg_last_set[regno],
11876 reg_last_set_label[regno], 1))
11877 return value;
11878
11879 return 0;
11880 }
11881
11882 /* Return nonzero if expression X refers to a REG or to memory
11883 that is set in an instruction more recent than FROM_CUID. */
11884
11885 static int
use_crosses_set_p(rtx x,int from_cuid)11886 use_crosses_set_p (rtx x, int from_cuid)
11887 {
11888 const char *fmt;
11889 int i;
11890 enum rtx_code code = GET_CODE (x);
11891
11892 if (code == REG)
11893 {
11894 unsigned int regno = REGNO (x);
11895 unsigned endreg = regno + (regno < FIRST_PSEUDO_REGISTER
11896 ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);
11897
11898 #ifdef PUSH_ROUNDING
11899 /* Don't allow uses of the stack pointer to be moved,
11900 because we don't know whether the move crosses a push insn. */
11901 if (regno == STACK_POINTER_REGNUM && PUSH_ARGS)
11902 return 1;
11903 #endif
11904 for (; regno < endreg; regno++)
11905 if (reg_last_set[regno]
11906 && INSN_CUID (reg_last_set[regno]) > from_cuid)
11907 return 1;
11908 return 0;
11909 }
11910
11911 if (code == MEM && mem_last_set > from_cuid)
11912 return 1;
11913
11914 fmt = GET_RTX_FORMAT (code);
11915
11916 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
11917 {
11918 if (fmt[i] == 'E')
11919 {
11920 int j;
11921 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
11922 if (use_crosses_set_p (XVECEXP (x, i, j), from_cuid))
11923 return 1;
11924 }
11925 else if (fmt[i] == 'e'
11926 && use_crosses_set_p (XEXP (x, i), from_cuid))
11927 return 1;
11928 }
11929 return 0;
11930 }
11931
11932 /* Define three variables used for communication between the following
11933 routines. */
11934
11935 static unsigned int reg_dead_regno, reg_dead_endregno;
11936 static int reg_dead_flag;
11937
11938 /* Function called via note_stores from reg_dead_at_p.
11939
11940 If DEST is within [reg_dead_regno, reg_dead_endregno), set
11941 reg_dead_flag to 1 if X is a CLOBBER and to -1 it is a SET. */
11942
11943 static void
reg_dead_at_p_1(rtx dest,rtx x,void * data ATTRIBUTE_UNUSED)11944 reg_dead_at_p_1 (rtx dest, rtx x, void *data ATTRIBUTE_UNUSED)
11945 {
11946 unsigned int regno, endregno;
11947
11948 if (GET_CODE (dest) != REG)
11949 return;
11950
11951 regno = REGNO (dest);
11952 endregno = regno + (regno < FIRST_PSEUDO_REGISTER
11953 ? HARD_REGNO_NREGS (regno, GET_MODE (dest)) : 1);
11954
11955 if (reg_dead_endregno > regno && reg_dead_regno < endregno)
11956 reg_dead_flag = (GET_CODE (x) == CLOBBER) ? 1 : -1;
11957 }
11958
11959 /* Return nonzero if REG is known to be dead at INSN.
11960
11961 We scan backwards from INSN. If we hit a REG_DEAD note or a CLOBBER
11962 referencing REG, it is dead. If we hit a SET referencing REG, it is
11963 live. Otherwise, see if it is live or dead at the start of the basic
11964 block we are in. Hard regs marked as being live in NEWPAT_USED_REGS
11965 must be assumed to be always live. */
11966
11967 static int
reg_dead_at_p(rtx reg,rtx insn)11968 reg_dead_at_p (rtx reg, rtx insn)
11969 {
11970 basic_block block;
11971 unsigned int i;
11972
11973 /* Set variables for reg_dead_at_p_1. */
11974 reg_dead_regno = REGNO (reg);
11975 reg_dead_endregno = reg_dead_regno + (reg_dead_regno < FIRST_PSEUDO_REGISTER
11976 ? HARD_REGNO_NREGS (reg_dead_regno,
11977 GET_MODE (reg))
11978 : 1);
11979
11980 reg_dead_flag = 0;
11981
11982 /* Check that reg isn't mentioned in NEWPAT_USED_REGS. */
11983 if (reg_dead_regno < FIRST_PSEUDO_REGISTER)
11984 {
11985 for (i = reg_dead_regno; i < reg_dead_endregno; i++)
11986 if (TEST_HARD_REG_BIT (newpat_used_regs, i))
11987 return 0;
11988 }
11989
11990 /* Scan backwards until we find a REG_DEAD note, SET, CLOBBER, label, or
11991 beginning of function. */
11992 for (; insn && GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != BARRIER;
11993 insn = prev_nonnote_insn (insn))
11994 {
11995 note_stores (PATTERN (insn), reg_dead_at_p_1, NULL);
11996 if (reg_dead_flag)
11997 return reg_dead_flag == 1 ? 1 : 0;
11998
11999 if (find_regno_note (insn, REG_DEAD, reg_dead_regno))
12000 return 1;
12001 }
12002
12003 /* Get the basic block that we were in. */
12004 if (insn == 0)
12005 block = ENTRY_BLOCK_PTR->next_bb;
12006 else
12007 {
12008 FOR_EACH_BB (block)
12009 if (insn == BB_HEAD (block))
12010 break;
12011
12012 if (block == EXIT_BLOCK_PTR)
12013 return 0;
12014 }
12015
12016 for (i = reg_dead_regno; i < reg_dead_endregno; i++)
12017 if (REGNO_REG_SET_P (block->global_live_at_start, i))
12018 return 0;
12019
12020 return 1;
12021 }
12022
12023 /* Note hard registers in X that are used. This code is similar to
12024 that in flow.c, but much simpler since we don't care about pseudos. */
12025
12026 static void
mark_used_regs_combine(rtx x)12027 mark_used_regs_combine (rtx x)
12028 {
12029 RTX_CODE code = GET_CODE (x);
12030 unsigned int regno;
12031 int i;
12032
12033 switch (code)
12034 {
12035 case LABEL_REF:
12036 case SYMBOL_REF:
12037 case CONST_INT:
12038 case CONST:
12039 case CONST_DOUBLE:
12040 case CONST_VECTOR:
12041 case PC:
12042 case ADDR_VEC:
12043 case ADDR_DIFF_VEC:
12044 case ASM_INPUT:
12045 #ifdef HAVE_cc0
12046 /* CC0 must die in the insn after it is set, so we don't need to take
12047 special note of it here. */
12048 case CC0:
12049 #endif
12050 return;
12051
12052 case CLOBBER:
12053 /* If we are clobbering a MEM, mark any hard registers inside the
12054 address as used. */
12055 if (GET_CODE (XEXP (x, 0)) == MEM)
12056 mark_used_regs_combine (XEXP (XEXP (x, 0), 0));
12057 return;
12058
12059 case REG:
12060 regno = REGNO (x);
12061 /* A hard reg in a wide mode may really be multiple registers.
12062 If so, mark all of them just like the first. */
12063 if (regno < FIRST_PSEUDO_REGISTER)
12064 {
12065 unsigned int endregno, r;
12066
12067 /* None of this applies to the stack, frame or arg pointers. */
12068 if (regno == STACK_POINTER_REGNUM
12069 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
12070 || regno == HARD_FRAME_POINTER_REGNUM
12071 #endif
12072 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
12073 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
12074 #endif
12075 || regno == FRAME_POINTER_REGNUM)
12076 return;
12077
12078 endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
12079 for (r = regno; r < endregno; r++)
12080 SET_HARD_REG_BIT (newpat_used_regs, r);
12081 }
12082 return;
12083
12084 case SET:
12085 {
12086 /* If setting a MEM, or a SUBREG of a MEM, then note any hard regs in
12087 the address. */
12088 rtx testreg = SET_DEST (x);
12089
12090 while (GET_CODE (testreg) == SUBREG
12091 || GET_CODE (testreg) == ZERO_EXTRACT
12092 || GET_CODE (testreg) == SIGN_EXTRACT
12093 || GET_CODE (testreg) == STRICT_LOW_PART)
12094 testreg = XEXP (testreg, 0);
12095
12096 if (GET_CODE (testreg) == MEM)
12097 mark_used_regs_combine (XEXP (testreg, 0));
12098
12099 mark_used_regs_combine (SET_SRC (x));
12100 }
12101 return;
12102
12103 default:
12104 break;
12105 }
12106
12107 /* Recursively scan the operands of this expression. */
12108
12109 {
12110 const char *fmt = GET_RTX_FORMAT (code);
12111
12112 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
12113 {
12114 if (fmt[i] == 'e')
12115 mark_used_regs_combine (XEXP (x, i));
12116 else if (fmt[i] == 'E')
12117 {
12118 int j;
12119
12120 for (j = 0; j < XVECLEN (x, i); j++)
12121 mark_used_regs_combine (XVECEXP (x, i, j));
12122 }
12123 }
12124 }
12125 }
12126
12127 /* Remove register number REGNO from the dead registers list of INSN.
12128
12129 Return the note used to record the death, if there was one. */
12130
12131 rtx
remove_death(unsigned int regno,rtx insn)12132 remove_death (unsigned int regno, rtx insn)
12133 {
12134 rtx note = find_regno_note (insn, REG_DEAD, regno);
12135
12136 if (note)
12137 {
12138 REG_N_DEATHS (regno)--;
12139 remove_note (insn, note);
12140 }
12141
12142 return note;
12143 }
12144
12145 /* For each register (hardware or pseudo) used within expression X, if its
12146 death is in an instruction with cuid between FROM_CUID (inclusive) and
12147 TO_INSN (exclusive), put a REG_DEAD note for that register in the
12148 list headed by PNOTES.
12149
12150 That said, don't move registers killed by maybe_kill_insn.
12151
12152 This is done when X is being merged by combination into TO_INSN. These
12153 notes will then be distributed as needed. */
12154
12155 static void
move_deaths(rtx x,rtx maybe_kill_insn,int from_cuid,rtx to_insn,rtx * pnotes)12156 move_deaths (rtx x, rtx maybe_kill_insn, int from_cuid, rtx to_insn,
12157 rtx *pnotes)
12158 {
12159 const char *fmt;
12160 int len, i;
12161 enum rtx_code code = GET_CODE (x);
12162
12163 if (code == REG)
12164 {
12165 unsigned int regno = REGNO (x);
12166 rtx where_dead = reg_last_death[regno];
12167 rtx before_dead, after_dead;
12168
12169 /* Don't move the register if it gets killed in between from and to. */
12170 if (maybe_kill_insn && reg_set_p (x, maybe_kill_insn)
12171 && ! reg_referenced_p (x, maybe_kill_insn))
12172 return;
12173
12174 /* WHERE_DEAD could be a USE insn made by combine, so first we
12175 make sure that we have insns with valid INSN_CUID values. */
12176 before_dead = where_dead;
12177 while (before_dead && INSN_UID (before_dead) > max_uid_cuid)
12178 before_dead = PREV_INSN (before_dead);
12179
12180 after_dead = where_dead;
12181 while (after_dead && INSN_UID (after_dead) > max_uid_cuid)
12182 after_dead = NEXT_INSN (after_dead);
12183
12184 if (before_dead && after_dead
12185 && INSN_CUID (before_dead) >= from_cuid
12186 && (INSN_CUID (after_dead) < INSN_CUID (to_insn)
12187 || (where_dead != after_dead
12188 && INSN_CUID (after_dead) == INSN_CUID (to_insn))))
12189 {
12190 rtx note = remove_death (regno, where_dead);
12191
12192 /* It is possible for the call above to return 0. This can occur
12193 when reg_last_death points to I2 or I1 that we combined with.
12194 In that case make a new note.
12195
12196 We must also check for the case where X is a hard register
12197 and NOTE is a death note for a range of hard registers
12198 including X. In that case, we must put REG_DEAD notes for
12199 the remaining registers in place of NOTE. */
12200
12201 if (note != 0 && regno < FIRST_PSEUDO_REGISTER
12202 && (GET_MODE_SIZE (GET_MODE (XEXP (note, 0)))
12203 > GET_MODE_SIZE (GET_MODE (x))))
12204 {
12205 unsigned int deadregno = REGNO (XEXP (note, 0));
12206 unsigned int deadend
12207 = (deadregno + HARD_REGNO_NREGS (deadregno,
12208 GET_MODE (XEXP (note, 0))));
12209 unsigned int ourend
12210 = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
12211 unsigned int i;
12212
12213 for (i = deadregno; i < deadend; i++)
12214 if (i < regno || i >= ourend)
12215 REG_NOTES (where_dead)
12216 = gen_rtx_EXPR_LIST (REG_DEAD,
12217 regno_reg_rtx[i],
12218 REG_NOTES (where_dead));
12219 }
12220
12221 /* If we didn't find any note, or if we found a REG_DEAD note that
12222 covers only part of the given reg, and we have a multi-reg hard
12223 register, then to be safe we must check for REG_DEAD notes
12224 for each register other than the first. They could have
12225 their own REG_DEAD notes lying around. */
12226 else if ((note == 0
12227 || (note != 0
12228 && (GET_MODE_SIZE (GET_MODE (XEXP (note, 0)))
12229 < GET_MODE_SIZE (GET_MODE (x)))))
12230 && regno < FIRST_PSEUDO_REGISTER
12231 && HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
12232 {
12233 unsigned int ourend
12234 = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
12235 unsigned int i, offset;
12236 rtx oldnotes = 0;
12237
12238 if (note)
12239 offset = HARD_REGNO_NREGS (regno, GET_MODE (XEXP (note, 0)));
12240 else
12241 offset = 1;
12242
12243 for (i = regno + offset; i < ourend; i++)
12244 move_deaths (regno_reg_rtx[i],
12245 maybe_kill_insn, from_cuid, to_insn, &oldnotes);
12246 }
12247
12248 if (note != 0 && GET_MODE (XEXP (note, 0)) == GET_MODE (x))
12249 {
12250 XEXP (note, 1) = *pnotes;
12251 *pnotes = note;
12252 }
12253 else
12254 *pnotes = gen_rtx_EXPR_LIST (REG_DEAD, x, *pnotes);
12255
12256 REG_N_DEATHS (regno)++;
12257 }
12258
12259 return;
12260 }
12261
12262 else if (GET_CODE (x) == SET)
12263 {
12264 rtx dest = SET_DEST (x);
12265
12266 move_deaths (SET_SRC (x), maybe_kill_insn, from_cuid, to_insn, pnotes);
12267
12268 /* In the case of a ZERO_EXTRACT, a STRICT_LOW_PART, or a SUBREG
12269 that accesses one word of a multi-word item, some
12270 piece of everything register in the expression is used by
12271 this insn, so remove any old death. */
12272 /* ??? So why do we test for equality of the sizes? */
12273
12274 if (GET_CODE (dest) == ZERO_EXTRACT
12275 || GET_CODE (dest) == STRICT_LOW_PART
12276 || (GET_CODE (dest) == SUBREG
12277 && (((GET_MODE_SIZE (GET_MODE (dest))
12278 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
12279 == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest)))
12280 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))))
12281 {
12282 move_deaths (dest, maybe_kill_insn, from_cuid, to_insn, pnotes);
12283 return;
12284 }
12285
12286 /* If this is some other SUBREG, we know it replaces the entire
12287 value, so use that as the destination. */
12288 if (GET_CODE (dest) == SUBREG)
12289 dest = SUBREG_REG (dest);
12290
12291 /* If this is a MEM, adjust deaths of anything used in the address.
12292 For a REG (the only other possibility), the entire value is
12293 being replaced so the old value is not used in this insn. */
12294
12295 if (GET_CODE (dest) == MEM)
12296 move_deaths (XEXP (dest, 0), maybe_kill_insn, from_cuid,
12297 to_insn, pnotes);
12298 return;
12299 }
12300
12301 else if (GET_CODE (x) == CLOBBER)
12302 return;
12303
12304 len = GET_RTX_LENGTH (code);
12305 fmt = GET_RTX_FORMAT (code);
12306
12307 for (i = 0; i < len; i++)
12308 {
12309 if (fmt[i] == 'E')
12310 {
12311 int j;
12312 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
12313 move_deaths (XVECEXP (x, i, j), maybe_kill_insn, from_cuid,
12314 to_insn, pnotes);
12315 }
12316 else if (fmt[i] == 'e')
12317 move_deaths (XEXP (x, i), maybe_kill_insn, from_cuid, to_insn, pnotes);
12318 }
12319 }
12320
12321 /* Return 1 if X is the target of a bit-field assignment in BODY, the
12322 pattern of an insn. X must be a REG. */
12323
12324 static int
reg_bitfield_target_p(rtx x,rtx body)12325 reg_bitfield_target_p (rtx x, rtx body)
12326 {
12327 int i;
12328
12329 if (GET_CODE (body) == SET)
12330 {
12331 rtx dest = SET_DEST (body);
12332 rtx target;
12333 unsigned int regno, tregno, endregno, endtregno;
12334
12335 if (GET_CODE (dest) == ZERO_EXTRACT)
12336 target = XEXP (dest, 0);
12337 else if (GET_CODE (dest) == STRICT_LOW_PART)
12338 target = SUBREG_REG (XEXP (dest, 0));
12339 else
12340 return 0;
12341
12342 if (GET_CODE (target) == SUBREG)
12343 target = SUBREG_REG (target);
12344
12345 if (GET_CODE (target) != REG)
12346 return 0;
12347
12348 tregno = REGNO (target), regno = REGNO (x);
12349 if (tregno >= FIRST_PSEUDO_REGISTER || regno >= FIRST_PSEUDO_REGISTER)
12350 return target == x;
12351
12352 endtregno = tregno + HARD_REGNO_NREGS (tregno, GET_MODE (target));
12353 endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
12354
12355 return endregno > tregno && regno < endtregno;
12356 }
12357
12358 else if (GET_CODE (body) == PARALLEL)
12359 for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
12360 if (reg_bitfield_target_p (x, XVECEXP (body, 0, i)))
12361 return 1;
12362
12363 return 0;
12364 }
12365
12366 /* Given a chain of REG_NOTES originally from FROM_INSN, try to place them
12367 as appropriate. I3 and I2 are the insns resulting from the combination
12368 insns including FROM (I2 may be zero).
12369
12370 Each note in the list is either ignored or placed on some insns, depending
12371 on the type of note. */
12372
12373 static void
distribute_notes(rtx notes,rtx from_insn,rtx i3,rtx i2)12374 distribute_notes (rtx notes, rtx from_insn, rtx i3, rtx i2)
12375 {
12376 rtx note, next_note;
12377 rtx tem;
12378
12379 for (note = notes; note; note = next_note)
12380 {
12381 rtx place = 0, place2 = 0;
12382
12383 /* If this NOTE references a pseudo register, ensure it references
12384 the latest copy of that register. */
12385 if (XEXP (note, 0) && GET_CODE (XEXP (note, 0)) == REG
12386 && REGNO (XEXP (note, 0)) >= FIRST_PSEUDO_REGISTER)
12387 XEXP (note, 0) = regno_reg_rtx[REGNO (XEXP (note, 0))];
12388
12389 next_note = XEXP (note, 1);
12390 switch (REG_NOTE_KIND (note))
12391 {
12392 case REG_BR_PROB:
12393 case REG_BR_PRED:
12394 /* Doesn't matter much where we put this, as long as it's somewhere.
12395 It is preferable to keep these notes on branches, which is most
12396 likely to be i3. */
12397 place = i3;
12398 break;
12399
12400 case REG_VALUE_PROFILE:
12401 /* Just get rid of this note, as it is unused later anyway. */
12402 break;
12403
12404 case REG_VTABLE_REF:
12405 /* ??? Should remain with *a particular* memory load. Given the
12406 nature of vtable data, the last insn seems relatively safe. */
12407 place = i3;
12408 break;
12409
12410 case REG_NON_LOCAL_GOTO:
12411 if (GET_CODE (i3) == JUMP_INSN)
12412 place = i3;
12413 else if (i2 && GET_CODE (i2) == JUMP_INSN)
12414 place = i2;
12415 else
12416 abort ();
12417 break;
12418
12419 case REG_EH_REGION:
12420 /* These notes must remain with the call or trapping instruction. */
12421 if (GET_CODE (i3) == CALL_INSN)
12422 place = i3;
12423 else if (i2 && GET_CODE (i2) == CALL_INSN)
12424 place = i2;
12425 else if (flag_non_call_exceptions)
12426 {
12427 if (may_trap_p (i3))
12428 place = i3;
12429 else if (i2 && may_trap_p (i2))
12430 place = i2;
12431 /* ??? Otherwise assume we've combined things such that we
12432 can now prove that the instructions can't trap. Drop the
12433 note in this case. */
12434 }
12435 else
12436 abort ();
12437 break;
12438
12439 case REG_ALWAYS_RETURN:
12440 case REG_NORETURN:
12441 case REG_SETJMP:
12442 /* These notes must remain with the call. It should not be
12443 possible for both I2 and I3 to be a call. */
12444 if (GET_CODE (i3) == CALL_INSN)
12445 place = i3;
12446 else if (i2 && GET_CODE (i2) == CALL_INSN)
12447 place = i2;
12448 else
12449 abort ();
12450 break;
12451
12452 case REG_UNUSED:
12453 /* Any clobbers for i3 may still exist, and so we must process
12454 REG_UNUSED notes from that insn.
12455
12456 Any clobbers from i2 or i1 can only exist if they were added by
12457 recog_for_combine. In that case, recog_for_combine created the
12458 necessary REG_UNUSED notes. Trying to keep any original
12459 REG_UNUSED notes from these insns can cause incorrect output
12460 if it is for the same register as the original i3 dest.
12461 In that case, we will notice that the register is set in i3,
12462 and then add a REG_UNUSED note for the destination of i3, which
12463 is wrong. However, it is possible to have REG_UNUSED notes from
12464 i2 or i1 for register which were both used and clobbered, so
12465 we keep notes from i2 or i1 if they will turn into REG_DEAD
12466 notes. */
12467
12468 /* If this register is set or clobbered in I3, put the note there
12469 unless there is one already. */
12470 if (reg_set_p (XEXP (note, 0), PATTERN (i3)))
12471 {
12472 if (from_insn != i3)
12473 break;
12474
12475 if (! (GET_CODE (XEXP (note, 0)) == REG
12476 ? find_regno_note (i3, REG_UNUSED, REGNO (XEXP (note, 0)))
12477 : find_reg_note (i3, REG_UNUSED, XEXP (note, 0))))
12478 place = i3;
12479 }
12480 /* Otherwise, if this register is used by I3, then this register
12481 now dies here, so we must put a REG_DEAD note here unless there
12482 is one already. */
12483 else if (reg_referenced_p (XEXP (note, 0), PATTERN (i3))
12484 && ! (GET_CODE (XEXP (note, 0)) == REG
12485 ? find_regno_note (i3, REG_DEAD,
12486 REGNO (XEXP (note, 0)))
12487 : find_reg_note (i3, REG_DEAD, XEXP (note, 0))))
12488 {
12489 PUT_REG_NOTE_KIND (note, REG_DEAD);
12490 place = i3;
12491 }
12492 break;
12493
12494 case REG_EQUAL:
12495 case REG_EQUIV:
12496 case REG_NOALIAS:
12497 /* These notes say something about results of an insn. We can
12498 only support them if they used to be on I3 in which case they
12499 remain on I3. Otherwise they are ignored.
12500
12501 If the note refers to an expression that is not a constant, we
12502 must also ignore the note since we cannot tell whether the
12503 equivalence is still true. It might be possible to do
12504 slightly better than this (we only have a problem if I2DEST
12505 or I1DEST is present in the expression), but it doesn't
12506 seem worth the trouble. */
12507
12508 if (from_insn == i3
12509 && (XEXP (note, 0) == 0 || CONSTANT_P (XEXP (note, 0))))
12510 place = i3;
12511 break;
12512
12513 case REG_INC:
12514 case REG_NO_CONFLICT:
12515 /* These notes say something about how a register is used. They must
12516 be present on any use of the register in I2 or I3. */
12517 if (reg_mentioned_p (XEXP (note, 0), PATTERN (i3)))
12518 place = i3;
12519
12520 if (i2 && reg_mentioned_p (XEXP (note, 0), PATTERN (i2)))
12521 {
12522 if (place)
12523 place2 = i2;
12524 else
12525 place = i2;
12526 }
12527 break;
12528
12529 case REG_LABEL:
12530 /* This can show up in several ways -- either directly in the
12531 pattern, or hidden off in the constant pool with (or without?)
12532 a REG_EQUAL note. */
12533 /* ??? Ignore the without-reg_equal-note problem for now. */
12534 if (reg_mentioned_p (XEXP (note, 0), PATTERN (i3))
12535 || ((tem = find_reg_note (i3, REG_EQUAL, NULL_RTX))
12536 && GET_CODE (XEXP (tem, 0)) == LABEL_REF
12537 && XEXP (XEXP (tem, 0), 0) == XEXP (note, 0)))
12538 place = i3;
12539
12540 if (i2
12541 && (reg_mentioned_p (XEXP (note, 0), PATTERN (i2))
12542 || ((tem = find_reg_note (i2, REG_EQUAL, NULL_RTX))
12543 && GET_CODE (XEXP (tem, 0)) == LABEL_REF
12544 && XEXP (XEXP (tem, 0), 0) == XEXP (note, 0))))
12545 {
12546 if (place)
12547 place2 = i2;
12548 else
12549 place = i2;
12550 }
12551
12552 /* Don't attach REG_LABEL note to a JUMP_INSN which has
12553 JUMP_LABEL already. Instead, decrement LABEL_NUSES. */
12554 if (place && GET_CODE (place) == JUMP_INSN && JUMP_LABEL (place))
12555 {
12556 if (JUMP_LABEL (place) != XEXP (note, 0))
12557 abort ();
12558 if (GET_CODE (JUMP_LABEL (place)) == CODE_LABEL)
12559 LABEL_NUSES (JUMP_LABEL (place))--;
12560 place = 0;
12561 }
12562 if (place2 && GET_CODE (place2) == JUMP_INSN && JUMP_LABEL (place2))
12563 {
12564 if (JUMP_LABEL (place2) != XEXP (note, 0))
12565 abort ();
12566 if (GET_CODE (JUMP_LABEL (place2)) == CODE_LABEL)
12567 LABEL_NUSES (JUMP_LABEL (place2))--;
12568 place2 = 0;
12569 }
12570 break;
12571
12572 case REG_NONNEG:
12573 /* This note says something about the value of a register prior
12574 to the execution of an insn. It is too much trouble to see
12575 if the note is still correct in all situations. It is better
12576 to simply delete it. */
12577 break;
12578
12579 case REG_RETVAL:
12580 /* If the insn previously containing this note still exists,
12581 put it back where it was. Otherwise move it to the previous
12582 insn. Adjust the corresponding REG_LIBCALL note. */
12583 if (GET_CODE (from_insn) != NOTE)
12584 place = from_insn;
12585 else
12586 {
12587 tem = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
12588 place = prev_real_insn (from_insn);
12589 if (tem && place)
12590 XEXP (tem, 0) = place;
12591 /* If we're deleting the last remaining instruction of a
12592 libcall sequence, don't add the notes. */
12593 else if (XEXP (note, 0) == from_insn)
12594 tem = place = 0;
12595 /* Don't add the dangling REG_RETVAL note. */
12596 else if (! tem)
12597 place = 0;
12598 }
12599 break;
12600
12601 case REG_LIBCALL:
12602 /* This is handled similarly to REG_RETVAL. */
12603 if (GET_CODE (from_insn) != NOTE)
12604 place = from_insn;
12605 else
12606 {
12607 tem = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
12608 place = next_real_insn (from_insn);
12609 if (tem && place)
12610 XEXP (tem, 0) = place;
12611 /* If we're deleting the last remaining instruction of a
12612 libcall sequence, don't add the notes. */
12613 else if (XEXP (note, 0) == from_insn)
12614 tem = place = 0;
12615 /* Don't add the dangling REG_LIBCALL note. */
12616 else if (! tem)
12617 place = 0;
12618 }
12619 break;
12620
12621 case REG_DEAD:
12622 /* If the register is used as an input in I3, it dies there.
12623 Similarly for I2, if it is nonzero and adjacent to I3.
12624
12625 If the register is not used as an input in either I3 or I2
12626 and it is not one of the registers we were supposed to eliminate,
12627 there are two possibilities. We might have a non-adjacent I2
12628 or we might have somehow eliminated an additional register
12629 from a computation. For example, we might have had A & B where
12630 we discover that B will always be zero. In this case we will
12631 eliminate the reference to A.
12632
12633 In both cases, we must search to see if we can find a previous
12634 use of A and put the death note there. */
12635
12636 if (from_insn
12637 && GET_CODE (from_insn) == CALL_INSN
12638 && find_reg_fusage (from_insn, USE, XEXP (note, 0)))
12639 place = from_insn;
12640 else if (reg_referenced_p (XEXP (note, 0), PATTERN (i3)))
12641 place = i3;
12642 else if (i2 != 0 && next_nonnote_insn (i2) == i3
12643 && reg_referenced_p (XEXP (note, 0), PATTERN (i2)))
12644 place = i2;
12645
12646 if (place == 0)
12647 {
12648 basic_block bb = this_basic_block;
12649
12650 for (tem = PREV_INSN (i3); place == 0; tem = PREV_INSN (tem))
12651 {
12652 if (! INSN_P (tem))
12653 {
12654 if (tem == BB_HEAD (bb))
12655 break;
12656 continue;
12657 }
12658
12659 /* If the register is being set at TEM, see if that is all
12660 TEM is doing. If so, delete TEM. Otherwise, make this
12661 into a REG_UNUSED note instead. Don't delete sets to
12662 global register vars. */
12663 if ((REGNO (XEXP (note, 0)) >= FIRST_PSEUDO_REGISTER
12664 || !global_regs[REGNO (XEXP (note, 0))])
12665 && reg_set_p (XEXP (note, 0), PATTERN (tem)))
12666 {
12667 rtx set = single_set (tem);
12668 rtx inner_dest = 0;
12669 #ifdef HAVE_cc0
12670 rtx cc0_setter = NULL_RTX;
12671 #endif
12672
12673 if (set != 0)
12674 for (inner_dest = SET_DEST (set);
12675 (GET_CODE (inner_dest) == STRICT_LOW_PART
12676 || GET_CODE (inner_dest) == SUBREG
12677 || GET_CODE (inner_dest) == ZERO_EXTRACT);
12678 inner_dest = XEXP (inner_dest, 0))
12679 ;
12680
12681 /* Verify that it was the set, and not a clobber that
12682 modified the register.
12683
12684 CC0 targets must be careful to maintain setter/user
12685 pairs. If we cannot delete the setter due to side
12686 effects, mark the user with an UNUSED note instead
12687 of deleting it. */
12688
12689 if (set != 0 && ! side_effects_p (SET_SRC (set))
12690 && rtx_equal_p (XEXP (note, 0), inner_dest)
12691 #ifdef HAVE_cc0
12692 && (! reg_mentioned_p (cc0_rtx, SET_SRC (set))
12693 || ((cc0_setter = prev_cc0_setter (tem)) != NULL
12694 && sets_cc0_p (PATTERN (cc0_setter)) > 0))
12695 #endif
12696 )
12697 {
12698 /* Move the notes and links of TEM elsewhere.
12699 This might delete other dead insns recursively.
12700 First set the pattern to something that won't use
12701 any register. */
12702 rtx old_notes = REG_NOTES (tem);
12703
12704 PATTERN (tem) = pc_rtx;
12705 REG_NOTES (tem) = NULL;
12706
12707 distribute_notes (old_notes, tem, tem, NULL_RTX);
12708 distribute_links (LOG_LINKS (tem));
12709
12710 PUT_CODE (tem, NOTE);
12711 NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED;
12712 NOTE_SOURCE_FILE (tem) = 0;
12713
12714 #ifdef HAVE_cc0
12715 /* Delete the setter too. */
12716 if (cc0_setter)
12717 {
12718 PATTERN (cc0_setter) = pc_rtx;
12719 old_notes = REG_NOTES (cc0_setter);
12720 REG_NOTES (cc0_setter) = NULL;
12721
12722 distribute_notes (old_notes, cc0_setter,
12723 cc0_setter, NULL_RTX);
12724 distribute_links (LOG_LINKS (cc0_setter));
12725
12726 PUT_CODE (cc0_setter, NOTE);
12727 NOTE_LINE_NUMBER (cc0_setter)
12728 = NOTE_INSN_DELETED;
12729 NOTE_SOURCE_FILE (cc0_setter) = 0;
12730 }
12731 #endif
12732 }
12733 /* If the register is both set and used here, put the
12734 REG_DEAD note here, but place a REG_UNUSED note
12735 here too unless there already is one. */
12736 else if (reg_referenced_p (XEXP (note, 0),
12737 PATTERN (tem)))
12738 {
12739 place = tem;
12740
12741 if (! find_regno_note (tem, REG_UNUSED,
12742 REGNO (XEXP (note, 0))))
12743 REG_NOTES (tem)
12744 = gen_rtx_EXPR_LIST (REG_UNUSED, XEXP (note, 0),
12745 REG_NOTES (tem));
12746 }
12747 else
12748 {
12749 PUT_REG_NOTE_KIND (note, REG_UNUSED);
12750
12751 /* If there isn't already a REG_UNUSED note, put one
12752 here. */
12753 if (! find_regno_note (tem, REG_UNUSED,
12754 REGNO (XEXP (note, 0))))
12755 place = tem;
12756 break;
12757 }
12758 }
12759 else if (reg_referenced_p (XEXP (note, 0), PATTERN (tem))
12760 || (GET_CODE (tem) == CALL_INSN
12761 && find_reg_fusage (tem, USE, XEXP (note, 0))))
12762 {
12763 place = tem;
12764
12765 /* If we are doing a 3->2 combination, and we have a
12766 register which formerly died in i3 and was not used
12767 by i2, which now no longer dies in i3 and is used in
12768 i2 but does not die in i2, and place is between i2
12769 and i3, then we may need to move a link from place to
12770 i2. */
12771 if (i2 && INSN_UID (place) <= max_uid_cuid
12772 && INSN_CUID (place) > INSN_CUID (i2)
12773 && from_insn
12774 && INSN_CUID (from_insn) > INSN_CUID (i2)
12775 && reg_referenced_p (XEXP (note, 0), PATTERN (i2)))
12776 {
12777 rtx links = LOG_LINKS (place);
12778 LOG_LINKS (place) = 0;
12779 distribute_links (links);
12780 }
12781 break;
12782 }
12783
12784 if (tem == BB_HEAD (bb))
12785 break;
12786 }
12787
12788 /* We haven't found an insn for the death note and it
12789 is still a REG_DEAD note, but we have hit the beginning
12790 of the block. If the existing life info says the reg
12791 was dead, there's nothing left to do. Otherwise, we'll
12792 need to do a global life update after combine. */
12793 if (REG_NOTE_KIND (note) == REG_DEAD && place == 0
12794 && REGNO_REG_SET_P (bb->global_live_at_start,
12795 REGNO (XEXP (note, 0))))
12796 SET_BIT (refresh_blocks, this_basic_block->index);
12797 }
12798
12799 /* If the register is set or already dead at PLACE, we needn't do
12800 anything with this note if it is still a REG_DEAD note.
12801 We can here if it is set at all, not if is it totally replace,
12802 which is what `dead_or_set_p' checks, so also check for it being
12803 set partially. */
12804
12805 if (place && REG_NOTE_KIND (note) == REG_DEAD)
12806 {
12807 unsigned int regno = REGNO (XEXP (note, 0));
12808
12809 /* Similarly, if the instruction on which we want to place
12810 the note is a noop, we'll need do a global live update
12811 after we remove them in delete_noop_moves. */
12812 if (noop_move_p (place))
12813 SET_BIT (refresh_blocks, this_basic_block->index);
12814
12815 if (dead_or_set_p (place, XEXP (note, 0))
12816 || reg_bitfield_target_p (XEXP (note, 0), PATTERN (place)))
12817 {
12818 /* Unless the register previously died in PLACE, clear
12819 reg_last_death. [I no longer understand why this is
12820 being done.] */
12821 if (reg_last_death[regno] != place)
12822 reg_last_death[regno] = 0;
12823 place = 0;
12824 }
12825 else
12826 reg_last_death[regno] = place;
12827
12828 /* If this is a death note for a hard reg that is occupying
12829 multiple registers, ensure that we are still using all
12830 parts of the object. If we find a piece of the object
12831 that is unused, we must arrange for an appropriate REG_DEAD
12832 note to be added for it. However, we can't just emit a USE
12833 and tag the note to it, since the register might actually
12834 be dead; so we recourse, and the recursive call then finds
12835 the previous insn that used this register. */
12836
12837 if (place && regno < FIRST_PSEUDO_REGISTER
12838 && HARD_REGNO_NREGS (regno, GET_MODE (XEXP (note, 0))) > 1)
12839 {
12840 unsigned int endregno
12841 = regno + HARD_REGNO_NREGS (regno,
12842 GET_MODE (XEXP (note, 0)));
12843 int all_used = 1;
12844 unsigned int i;
12845
12846 for (i = regno; i < endregno; i++)
12847 if ((! refers_to_regno_p (i, i + 1, PATTERN (place), 0)
12848 && ! find_regno_fusage (place, USE, i))
12849 || dead_or_set_regno_p (place, i))
12850 all_used = 0;
12851
12852 if (! all_used)
12853 {
12854 /* Put only REG_DEAD notes for pieces that are
12855 not already dead or set. */
12856
12857 for (i = regno; i < endregno;
12858 i += HARD_REGNO_NREGS (i, reg_raw_mode[i]))
12859 {
12860 rtx piece = regno_reg_rtx[i];
12861 basic_block bb = this_basic_block;
12862
12863 if (! dead_or_set_p (place, piece)
12864 && ! reg_bitfield_target_p (piece,
12865 PATTERN (place)))
12866 {
12867 rtx new_note
12868 = gen_rtx_EXPR_LIST (REG_DEAD, piece, NULL_RTX);
12869
12870 distribute_notes (new_note, place, place,
12871 NULL_RTX);
12872 }
12873 else if (! refers_to_regno_p (i, i + 1,
12874 PATTERN (place), 0)
12875 && ! find_regno_fusage (place, USE, i))
12876 for (tem = PREV_INSN (place); ;
12877 tem = PREV_INSN (tem))
12878 {
12879 if (! INSN_P (tem))
12880 {
12881 if (tem == BB_HEAD (bb))
12882 {
12883 SET_BIT (refresh_blocks,
12884 this_basic_block->index);
12885 break;
12886 }
12887 continue;
12888 }
12889 if (dead_or_set_p (tem, piece)
12890 || reg_bitfield_target_p (piece,
12891 PATTERN (tem)))
12892 {
12893 REG_NOTES (tem)
12894 = gen_rtx_EXPR_LIST (REG_UNUSED, piece,
12895 REG_NOTES (tem));
12896 break;
12897 }
12898 }
12899
12900 }
12901
12902 place = 0;
12903 }
12904 }
12905 }
12906 break;
12907
12908 default:
12909 /* Any other notes should not be present at this point in the
12910 compilation. */
12911 abort ();
12912 }
12913
12914 if (place)
12915 {
12916 XEXP (note, 1) = REG_NOTES (place);
12917 REG_NOTES (place) = note;
12918 }
12919 else if ((REG_NOTE_KIND (note) == REG_DEAD
12920 || REG_NOTE_KIND (note) == REG_UNUSED)
12921 && GET_CODE (XEXP (note, 0)) == REG)
12922 REG_N_DEATHS (REGNO (XEXP (note, 0)))--;
12923
12924 if (place2)
12925 {
12926 if ((REG_NOTE_KIND (note) == REG_DEAD
12927 || REG_NOTE_KIND (note) == REG_UNUSED)
12928 && GET_CODE (XEXP (note, 0)) == REG)
12929 REG_N_DEATHS (REGNO (XEXP (note, 0)))++;
12930
12931 REG_NOTES (place2) = gen_rtx_fmt_ee (GET_CODE (note),
12932 REG_NOTE_KIND (note),
12933 XEXP (note, 0),
12934 REG_NOTES (place2));
12935 }
12936 }
12937 }
12938
12939 /* Similarly to above, distribute the LOG_LINKS that used to be present on
12940 I3, I2, and I1 to new locations. This is also called to add a link
12941 pointing at I3 when I3's destination is changed. */
12942
12943 static void
distribute_links(rtx links)12944 distribute_links (rtx links)
12945 {
12946 rtx link, next_link;
12947
12948 for (link = links; link; link = next_link)
12949 {
12950 rtx place = 0;
12951 rtx insn;
12952 rtx set, reg;
12953
12954 next_link = XEXP (link, 1);
12955
12956 /* If the insn that this link points to is a NOTE or isn't a single
12957 set, ignore it. In the latter case, it isn't clear what we
12958 can do other than ignore the link, since we can't tell which
12959 register it was for. Such links wouldn't be used by combine
12960 anyway.
12961
12962 It is not possible for the destination of the target of the link to
12963 have been changed by combine. The only potential of this is if we
12964 replace I3, I2, and I1 by I3 and I2. But in that case the
12965 destination of I2 also remains unchanged. */
12966
12967 if (GET_CODE (XEXP (link, 0)) == NOTE
12968 || (set = single_set (XEXP (link, 0))) == 0)
12969 continue;
12970
12971 reg = SET_DEST (set);
12972 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
12973 || GET_CODE (reg) == SIGN_EXTRACT
12974 || GET_CODE (reg) == STRICT_LOW_PART)
12975 reg = XEXP (reg, 0);
12976
12977 /* A LOG_LINK is defined as being placed on the first insn that uses
12978 a register and points to the insn that sets the register. Start
12979 searching at the next insn after the target of the link and stop
12980 when we reach a set of the register or the end of the basic block.
12981
12982 Note that this correctly handles the link that used to point from
12983 I3 to I2. Also note that not much searching is typically done here
12984 since most links don't point very far away. */
12985
12986 for (insn = NEXT_INSN (XEXP (link, 0));
12987 (insn && (this_basic_block->next_bb == EXIT_BLOCK_PTR
12988 || BB_HEAD (this_basic_block->next_bb) != insn));
12989 insn = NEXT_INSN (insn))
12990 if (INSN_P (insn) && reg_overlap_mentioned_p (reg, PATTERN (insn)))
12991 {
12992 if (reg_referenced_p (reg, PATTERN (insn)))
12993 place = insn;
12994 break;
12995 }
12996 else if (GET_CODE (insn) == CALL_INSN
12997 && find_reg_fusage (insn, USE, reg))
12998 {
12999 place = insn;
13000 break;
13001 }
13002 else if (INSN_P (insn) && reg_set_p (reg, insn))
13003 break;
13004
13005 /* If we found a place to put the link, place it there unless there
13006 is already a link to the same insn as LINK at that point. */
13007
13008 if (place)
13009 {
13010 rtx link2;
13011
13012 for (link2 = LOG_LINKS (place); link2; link2 = XEXP (link2, 1))
13013 if (XEXP (link2, 0) == XEXP (link, 0))
13014 break;
13015
13016 if (link2 == 0)
13017 {
13018 XEXP (link, 1) = LOG_LINKS (place);
13019 LOG_LINKS (place) = link;
13020
13021 /* Set added_links_insn to the earliest insn we added a
13022 link to. */
13023 if (added_links_insn == 0
13024 || INSN_CUID (added_links_insn) > INSN_CUID (place))
13025 added_links_insn = place;
13026 }
13027 }
13028 }
13029 }
13030
13031 /* Compute INSN_CUID for INSN, which is an insn made by combine. */
13032
13033 static int
insn_cuid(rtx insn)13034 insn_cuid (rtx insn)
13035 {
13036 while (insn != 0 && INSN_UID (insn) > max_uid_cuid
13037 && GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == USE)
13038 insn = NEXT_INSN (insn);
13039
13040 if (INSN_UID (insn) > max_uid_cuid)
13041 abort ();
13042
13043 return INSN_CUID (insn);
13044 }
13045
13046 void
dump_combine_stats(FILE * file)13047 dump_combine_stats (FILE *file)
13048 {
13049 fnotice
13050 (file,
13051 ";; Combiner statistics: %d attempts, %d substitutions (%d requiring new space),\n;; %d successes.\n\n",
13052 combine_attempts, combine_merges, combine_extras, combine_successes);
13053 }
13054
13055 void
dump_combine_total_stats(FILE * file)13056 dump_combine_total_stats (FILE *file)
13057 {
13058 fnotice
13059 (file,
13060 "\n;; Combiner totals: %d attempts, %d substitutions (%d requiring new space),\n;; %d successes.\n",
13061 total_attempts, total_merges, total_extras, total_successes);
13062 }
13063