Merge branches/gcc-4_8-branch rev 208968.
[official-gcc.git] / gcc-4_8-branch / gcc / cselib.c
blob334d9552abf752eb8f301ab94a74fa0aeab38e0a
1 /* Common subexpression elimination library for GNU compiler.
2 Copyright (C) 1987-2013 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "tm.h"
25 #include "rtl.h"
26 #include "tree.h"/* FIXME: For hashing DEBUG_EXPR & friends. */
27 #include "tm_p.h"
28 #include "regs.h"
29 #include "hard-reg-set.h"
30 #include "flags.h"
31 #include "insn-config.h"
32 #include "recog.h"
33 #include "function.h"
34 #include "emit-rtl.h"
35 #include "diagnostic-core.h"
36 #include "ggc.h"
37 #include "hashtab.h"
38 #include "dumpfile.h"
39 #include "cselib.h"
40 #include "valtrack.h"
41 #include "params.h"
42 #include "alloc-pool.h"
43 #include "target.h"
44 #include "bitmap.h"
46 /* A list of cselib_val structures. */
47 struct elt_list {
48 struct elt_list *next;
49 cselib_val *elt;
52 static bool cselib_record_memory;
53 static bool cselib_preserve_constants;
54 static bool cselib_any_perm_equivs;
55 static int entry_and_rtx_equal_p (const void *, const void *);
56 static hashval_t get_value_hash (const void *);
57 static struct elt_list *new_elt_list (struct elt_list *, cselib_val *);
58 static void new_elt_loc_list (cselib_val *, rtx);
59 static void unchain_one_value (cselib_val *);
60 static void unchain_one_elt_list (struct elt_list **);
61 static void unchain_one_elt_loc_list (struct elt_loc_list **);
62 static int discard_useless_locs (void **, void *);
63 static int discard_useless_values (void **, void *);
64 static void remove_useless_values (void);
65 static int rtx_equal_for_cselib_1 (rtx, rtx, enum machine_mode);
66 static unsigned int cselib_hash_rtx (rtx, int, enum machine_mode);
67 static cselib_val *new_cselib_val (unsigned int, enum machine_mode, rtx);
68 static void add_mem_for_addr (cselib_val *, cselib_val *, rtx);
69 static cselib_val *cselib_lookup_mem (rtx, int);
70 static void cselib_invalidate_regno (unsigned int, enum machine_mode);
71 static void cselib_invalidate_mem (rtx);
72 static void cselib_record_set (rtx, cselib_val *, cselib_val *);
73 static void cselib_record_sets (rtx);
75 struct expand_value_data
77 bitmap regs_active;
78 cselib_expand_callback callback;
79 void *callback_arg;
80 bool dummy;
83 static rtx cselib_expand_value_rtx_1 (rtx, struct expand_value_data *, int);
85 /* There are three ways in which cselib can look up an rtx:
86 - for a REG, the reg_values table (which is indexed by regno) is used
87 - for a MEM, we recursively look up its address and then follow the
88 addr_list of that value
89 - for everything else, we compute a hash value and go through the hash
90 table. Since different rtx's can still have the same hash value,
91 this involves walking the table entries for a given value and comparing
92 the locations of the entries with the rtx we are looking up. */
94 /* A table that enables us to look up elts by their value. */
95 static htab_t cselib_hash_table;
97 /* This is a global so we don't have to pass this through every function.
98 It is used in new_elt_loc_list to set SETTING_INSN. */
99 static rtx cselib_current_insn;
101 /* The unique id that the next create value will take. */
102 static unsigned int next_uid;
104 /* The number of registers we had when the varrays were last resized. */
105 static unsigned int cselib_nregs;
107 /* Count values without known locations, or with only locations that
108 wouldn't have been known except for debug insns. Whenever this
109 grows too big, we remove these useless values from the table.
111 Counting values with only debug values is a bit tricky. We don't
112 want to increment n_useless_values when we create a value for a
113 debug insn, for this would get n_useless_values out of sync, but we
114 want increment it if all locs in the list that were ever referenced
115 in nondebug insns are removed from the list.
117 In the general case, once we do that, we'd have to stop accepting
118 nondebug expressions in the loc list, to avoid having two values
119 equivalent that, without debug insns, would have been made into
120 separate values. However, because debug insns never introduce
121 equivalences themselves (no assignments), the only means for
122 growing loc lists is through nondebug assignments. If the locs
123 also happen to be referenced in debug insns, it will work just fine.
125 A consequence of this is that there's at most one debug-only loc in
126 each loc list. If we keep it in the first entry, testing whether
127 we have a debug-only loc list takes O(1).
129 Furthermore, since any additional entry in a loc list containing a
130 debug loc would have to come from an assignment (nondebug) that
131 references both the initial debug loc and the newly-equivalent loc,
132 the initial debug loc would be promoted to a nondebug loc, and the
133 loc list would not contain debug locs any more.
135 So the only case we have to be careful with in order to keep
136 n_useless_values in sync between debug and nondebug compilations is
137 to avoid incrementing n_useless_values when removing the single loc
138 from a value that turns out to not appear outside debug values. We
139 increment n_useless_debug_values instead, and leave such values
140 alone until, for other reasons, we garbage-collect useless
141 values. */
142 static int n_useless_values;
143 static int n_useless_debug_values;
145 /* Count values whose locs have been taken exclusively from debug
146 insns for the entire life of the value. */
147 static int n_debug_values;
149 /* Number of useless values before we remove them from the hash table. */
150 #define MAX_USELESS_VALUES 32
152 /* This table maps from register number to values. It does not
153 contain pointers to cselib_val structures, but rather elt_lists.
154 The purpose is to be able to refer to the same register in
155 different modes. The first element of the list defines the mode in
156 which the register was set; if the mode is unknown or the value is
157 no longer valid in that mode, ELT will be NULL for the first
158 element. */
159 static struct elt_list **reg_values;
160 static unsigned int reg_values_size;
161 #define REG_VALUES(i) reg_values[i]
163 /* The largest number of hard regs used by any entry added to the
164 REG_VALUES table. Cleared on each cselib_clear_table() invocation. */
165 static unsigned int max_value_regs;
167 /* Here the set of indices I with REG_VALUES(I) != 0 is saved. This is used
168 in cselib_clear_table() for fast emptying. */
169 static unsigned int *used_regs;
170 static unsigned int n_used_regs;
172 /* We pass this to cselib_invalidate_mem to invalidate all of
173 memory for a non-const call instruction. */
174 static GTY(()) rtx callmem;
176 /* Set by discard_useless_locs if it deleted the last location of any
177 value. */
178 static int values_became_useless;
180 /* Used as stop element of the containing_mem list so we can check
181 presence in the list by checking the next pointer. */
182 static cselib_val dummy_val;
184 /* If non-NULL, value of the eliminated arg_pointer_rtx or frame_pointer_rtx
185 that is constant through the whole function and should never be
186 eliminated. */
187 static cselib_val *cfa_base_preserved_val;
188 static unsigned int cfa_base_preserved_regno = INVALID_REGNUM;
190 /* Used to list all values that contain memory reference.
191 May or may not contain the useless values - the list is compacted
192 each time memory is invalidated. */
193 static cselib_val *first_containing_mem = &dummy_val;
194 static alloc_pool elt_loc_list_pool, elt_list_pool, cselib_val_pool, value_pool;
196 /* If nonnull, cselib will call this function before freeing useless
197 VALUEs. A VALUE is deemed useless if its "locs" field is null. */
198 void (*cselib_discard_hook) (cselib_val *);
200 /* If nonnull, cselib will call this function before recording sets or
201 even clobbering outputs of INSN. All the recorded sets will be
202 represented in the array sets[n_sets]. new_val_min can be used to
203 tell whether values present in sets are introduced by this
204 instruction. */
205 void (*cselib_record_sets_hook) (rtx insn, struct cselib_set *sets,
206 int n_sets);
208 #define PRESERVED_VALUE_P(RTX) \
209 (RTL_FLAG_CHECK1("PRESERVED_VALUE_P", (RTX), VALUE)->unchanging)
211 #define SP_BASED_VALUE_P(RTX) \
212 (RTL_FLAG_CHECK1("SP_BASED_VALUE_P", (RTX), VALUE)->jump)
216 /* Allocate a struct elt_list and fill in its two elements with the
217 arguments. */
219 static inline struct elt_list *
220 new_elt_list (struct elt_list *next, cselib_val *elt)
222 struct elt_list *el;
223 el = (struct elt_list *) pool_alloc (elt_list_pool);
224 el->next = next;
225 el->elt = elt;
226 return el;
229 /* Allocate a struct elt_loc_list with LOC and prepend it to VAL's loc
230 list. */
232 static inline void
233 new_elt_loc_list (cselib_val *val, rtx loc)
235 struct elt_loc_list *el, *next = val->locs;
237 gcc_checking_assert (!next || !next->setting_insn
238 || !DEBUG_INSN_P (next->setting_insn)
239 || cselib_current_insn == next->setting_insn);
241 /* If we're creating the first loc in a debug insn context, we've
242 just created a debug value. Count it. */
243 if (!next && cselib_current_insn && DEBUG_INSN_P (cselib_current_insn))
244 n_debug_values++;
246 val = canonical_cselib_val (val);
247 next = val->locs;
249 if (GET_CODE (loc) == VALUE)
251 loc = canonical_cselib_val (CSELIB_VAL_PTR (loc))->val_rtx;
253 gcc_checking_assert (PRESERVED_VALUE_P (loc)
254 == PRESERVED_VALUE_P (val->val_rtx));
256 if (val->val_rtx == loc)
257 return;
258 else if (val->uid > CSELIB_VAL_PTR (loc)->uid)
260 /* Reverse the insertion. */
261 new_elt_loc_list (CSELIB_VAL_PTR (loc), val->val_rtx);
262 return;
265 gcc_checking_assert (val->uid < CSELIB_VAL_PTR (loc)->uid);
267 if (CSELIB_VAL_PTR (loc)->locs)
269 /* Bring all locs from LOC to VAL. */
270 for (el = CSELIB_VAL_PTR (loc)->locs; el->next; el = el->next)
272 /* Adjust values that have LOC as canonical so that VAL
273 becomes their canonical. */
274 if (el->loc && GET_CODE (el->loc) == VALUE)
276 gcc_checking_assert (CSELIB_VAL_PTR (el->loc)->locs->loc
277 == loc);
278 CSELIB_VAL_PTR (el->loc)->locs->loc = val->val_rtx;
281 el->next = val->locs;
282 next = val->locs = CSELIB_VAL_PTR (loc)->locs;
285 if (CSELIB_VAL_PTR (loc)->addr_list)
287 /* Bring in addr_list into canonical node. */
288 struct elt_list *last = CSELIB_VAL_PTR (loc)->addr_list;
289 while (last->next)
290 last = last->next;
291 last->next = val->addr_list;
292 val->addr_list = CSELIB_VAL_PTR (loc)->addr_list;
293 CSELIB_VAL_PTR (loc)->addr_list = NULL;
296 if (CSELIB_VAL_PTR (loc)->next_containing_mem != NULL
297 && val->next_containing_mem == NULL)
299 /* Add VAL to the containing_mem list after LOC. LOC will
300 be removed when we notice it doesn't contain any
301 MEMs. */
302 val->next_containing_mem = CSELIB_VAL_PTR (loc)->next_containing_mem;
303 CSELIB_VAL_PTR (loc)->next_containing_mem = val;
306 /* Chain LOC back to VAL. */
307 el = (struct elt_loc_list *) pool_alloc (elt_loc_list_pool);
308 el->loc = val->val_rtx;
309 el->setting_insn = cselib_current_insn;
310 el->next = NULL;
311 CSELIB_VAL_PTR (loc)->locs = el;
314 el = (struct elt_loc_list *) pool_alloc (elt_loc_list_pool);
315 el->loc = loc;
316 el->setting_insn = cselib_current_insn;
317 el->next = next;
318 val->locs = el;
321 /* Promote loc L to a nondebug cselib_current_insn if L is marked as
322 originating from a debug insn, maintaining the debug values
323 count. */
325 static inline void
326 promote_debug_loc (struct elt_loc_list *l)
328 if (l && l->setting_insn && DEBUG_INSN_P (l->setting_insn)
329 && (!cselib_current_insn || !DEBUG_INSN_P (cselib_current_insn)))
331 n_debug_values--;
332 l->setting_insn = cselib_current_insn;
333 if (cselib_preserve_constants && l->next)
335 gcc_assert (l->next->setting_insn
336 && DEBUG_INSN_P (l->next->setting_insn)
337 && !l->next->next);
338 l->next->setting_insn = cselib_current_insn;
340 else
341 gcc_assert (!l->next);
345 /* The elt_list at *PL is no longer needed. Unchain it and free its
346 storage. */
348 static inline void
349 unchain_one_elt_list (struct elt_list **pl)
351 struct elt_list *l = *pl;
353 *pl = l->next;
354 pool_free (elt_list_pool, l);
357 /* Likewise for elt_loc_lists. */
359 static void
360 unchain_one_elt_loc_list (struct elt_loc_list **pl)
362 struct elt_loc_list *l = *pl;
364 *pl = l->next;
365 pool_free (elt_loc_list_pool, l);
368 /* Likewise for cselib_vals. This also frees the addr_list associated with
369 V. */
371 static void
372 unchain_one_value (cselib_val *v)
374 while (v->addr_list)
375 unchain_one_elt_list (&v->addr_list);
377 pool_free (cselib_val_pool, v);
380 /* Remove all entries from the hash table. Also used during
381 initialization. */
383 void
384 cselib_clear_table (void)
386 cselib_reset_table (1);
389 /* Return TRUE if V is a constant, a function invariant or a VALUE
390 equivalence; FALSE otherwise. */
392 static bool
393 invariant_or_equiv_p (cselib_val *v)
395 struct elt_loc_list *l;
397 if (v == cfa_base_preserved_val)
398 return true;
400 /* Keep VALUE equivalences around. */
401 for (l = v->locs; l; l = l->next)
402 if (GET_CODE (l->loc) == VALUE)
403 return true;
405 if (v->locs != NULL
406 && v->locs->next == NULL)
408 if (CONSTANT_P (v->locs->loc)
409 && (GET_CODE (v->locs->loc) != CONST
410 || !references_value_p (v->locs->loc, 0)))
411 return true;
412 /* Although a debug expr may be bound to different expressions,
413 we can preserve it as if it was constant, to get unification
414 and proper merging within var-tracking. */
415 if (GET_CODE (v->locs->loc) == DEBUG_EXPR
416 || GET_CODE (v->locs->loc) == DEBUG_IMPLICIT_PTR
417 || GET_CODE (v->locs->loc) == ENTRY_VALUE
418 || GET_CODE (v->locs->loc) == DEBUG_PARAMETER_REF)
419 return true;
421 /* (plus (value V) (const_int C)) is invariant iff V is invariant. */
422 if (GET_CODE (v->locs->loc) == PLUS
423 && CONST_INT_P (XEXP (v->locs->loc, 1))
424 && GET_CODE (XEXP (v->locs->loc, 0)) == VALUE
425 && invariant_or_equiv_p (CSELIB_VAL_PTR (XEXP (v->locs->loc, 0))))
426 return true;
429 return false;
432 /* Remove from hash table all VALUEs except constants, function
433 invariants and VALUE equivalences. */
435 static int
436 preserve_constants_and_equivs (void **x, void *info ATTRIBUTE_UNUSED)
438 cselib_val *v = (cselib_val *)*x;
440 if (!invariant_or_equiv_p (v))
441 htab_clear_slot (cselib_hash_table, x);
442 return 1;
445 /* Remove all entries from the hash table, arranging for the next
446 value to be numbered NUM. */
448 void
449 cselib_reset_table (unsigned int num)
451 unsigned int i;
453 max_value_regs = 0;
455 if (cfa_base_preserved_val)
457 unsigned int regno = cfa_base_preserved_regno;
458 unsigned int new_used_regs = 0;
459 for (i = 0; i < n_used_regs; i++)
460 if (used_regs[i] == regno)
462 new_used_regs = 1;
463 continue;
465 else
466 REG_VALUES (used_regs[i]) = 0;
467 gcc_assert (new_used_regs == 1);
468 n_used_regs = new_used_regs;
469 used_regs[0] = regno;
470 max_value_regs
471 = hard_regno_nregs[regno][GET_MODE (cfa_base_preserved_val->locs->loc)];
473 else
475 for (i = 0; i < n_used_regs; i++)
476 REG_VALUES (used_regs[i]) = 0;
477 n_used_regs = 0;
480 if (cselib_preserve_constants)
481 htab_traverse (cselib_hash_table, preserve_constants_and_equivs, NULL);
482 else
484 htab_empty (cselib_hash_table);
485 gcc_checking_assert (!cselib_any_perm_equivs);
488 n_useless_values = 0;
489 n_useless_debug_values = 0;
490 n_debug_values = 0;
492 next_uid = num;
494 first_containing_mem = &dummy_val;
497 /* Return the number of the next value that will be generated. */
499 unsigned int
500 cselib_get_next_uid (void)
502 return next_uid;
505 /* See the documentation of cselib_find_slot below. */
506 static enum machine_mode find_slot_memmode;
508 /* Search for X, whose hashcode is HASH, in CSELIB_HASH_TABLE,
509 INSERTing if requested. When X is part of the address of a MEM,
510 MEMMODE should specify the mode of the MEM. While searching the
511 table, MEMMODE is held in FIND_SLOT_MEMMODE, so that autoinc RTXs
512 in X can be resolved. */
514 static void **
515 cselib_find_slot (rtx x, hashval_t hash, enum insert_option insert,
516 enum machine_mode memmode)
518 void **slot;
519 find_slot_memmode = memmode;
520 slot = htab_find_slot_with_hash (cselib_hash_table, x, hash, insert);
521 find_slot_memmode = VOIDmode;
522 return slot;
525 /* The equality test for our hash table. The first argument ENTRY is a table
526 element (i.e. a cselib_val), while the second arg X is an rtx. We know
527 that all callers of htab_find_slot_with_hash will wrap CONST_INTs into a
528 CONST of an appropriate mode. */
530 static int
531 entry_and_rtx_equal_p (const void *entry, const void *x_arg)
533 struct elt_loc_list *l;
534 const cselib_val *const v = (const cselib_val *) entry;
535 rtx x = CONST_CAST_RTX ((const_rtx)x_arg);
536 enum machine_mode mode = GET_MODE (x);
538 gcc_assert (!CONST_SCALAR_INT_P (x) && GET_CODE (x) != CONST_FIXED);
540 if (mode != GET_MODE (v->val_rtx))
541 return 0;
543 /* Unwrap X if necessary. */
544 if (GET_CODE (x) == CONST
545 && (CONST_SCALAR_INT_P (XEXP (x, 0))
546 || GET_CODE (XEXP (x, 0)) == CONST_FIXED))
547 x = XEXP (x, 0);
549 /* We don't guarantee that distinct rtx's have different hash values,
550 so we need to do a comparison. */
551 for (l = v->locs; l; l = l->next)
552 if (rtx_equal_for_cselib_1 (l->loc, x, find_slot_memmode))
554 promote_debug_loc (l);
555 return 1;
558 return 0;
561 /* The hash function for our hash table. The value is always computed with
562 cselib_hash_rtx when adding an element; this function just extracts the
563 hash value from a cselib_val structure. */
565 static hashval_t
566 get_value_hash (const void *entry)
568 const cselib_val *const v = (const cselib_val *) entry;
569 return v->hash;
572 /* Return true if X contains a VALUE rtx. If ONLY_USELESS is set, we
573 only return true for values which point to a cselib_val whose value
574 element has been set to zero, which implies the cselib_val will be
575 removed. */
578 references_value_p (const_rtx x, int only_useless)
580 const enum rtx_code code = GET_CODE (x);
581 const char *fmt = GET_RTX_FORMAT (code);
582 int i, j;
584 if (GET_CODE (x) == VALUE
585 && (! only_useless ||
586 (CSELIB_VAL_PTR (x)->locs == 0 && !PRESERVED_VALUE_P (x))))
587 return 1;
589 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
591 if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless))
592 return 1;
593 else if (fmt[i] == 'E')
594 for (j = 0; j < XVECLEN (x, i); j++)
595 if (references_value_p (XVECEXP (x, i, j), only_useless))
596 return 1;
599 return 0;
602 /* For all locations found in X, delete locations that reference useless
603 values (i.e. values without any location). Called through
604 htab_traverse. */
606 static int
607 discard_useless_locs (void **x, void *info ATTRIBUTE_UNUSED)
609 cselib_val *v = (cselib_val *)*x;
610 struct elt_loc_list **p = &v->locs;
611 bool had_locs = v->locs != NULL;
612 rtx setting_insn = v->locs ? v->locs->setting_insn : NULL;
614 while (*p)
616 if (references_value_p ((*p)->loc, 1))
617 unchain_one_elt_loc_list (p);
618 else
619 p = &(*p)->next;
622 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
624 if (setting_insn && DEBUG_INSN_P (setting_insn))
625 n_useless_debug_values++;
626 else
627 n_useless_values++;
628 values_became_useless = 1;
630 return 1;
633 /* If X is a value with no locations, remove it from the hashtable. */
635 static int
636 discard_useless_values (void **x, void *info ATTRIBUTE_UNUSED)
638 cselib_val *v = (cselib_val *)*x;
640 if (v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
642 if (cselib_discard_hook)
643 cselib_discard_hook (v);
645 CSELIB_VAL_PTR (v->val_rtx) = NULL;
646 htab_clear_slot (cselib_hash_table, x);
647 unchain_one_value (v);
648 n_useless_values--;
651 return 1;
654 /* Clean out useless values (i.e. those which no longer have locations
655 associated with them) from the hash table. */
657 static void
658 remove_useless_values (void)
660 cselib_val **p, *v;
662 /* First pass: eliminate locations that reference the value. That in
663 turn can make more values useless. */
666 values_became_useless = 0;
667 htab_traverse (cselib_hash_table, discard_useless_locs, 0);
669 while (values_became_useless);
671 /* Second pass: actually remove the values. */
673 p = &first_containing_mem;
674 for (v = *p; v != &dummy_val; v = v->next_containing_mem)
675 if (v->locs && v == canonical_cselib_val (v))
677 *p = v;
678 p = &(*p)->next_containing_mem;
680 *p = &dummy_val;
682 n_useless_values += n_useless_debug_values;
683 n_debug_values -= n_useless_debug_values;
684 n_useless_debug_values = 0;
686 htab_traverse (cselib_hash_table, discard_useless_values, 0);
688 gcc_assert (!n_useless_values);
691 /* Arrange for a value to not be removed from the hash table even if
692 it becomes useless. */
694 void
695 cselib_preserve_value (cselib_val *v)
697 PRESERVED_VALUE_P (v->val_rtx) = 1;
700 /* Test whether a value is preserved. */
702 bool
703 cselib_preserved_value_p (cselib_val *v)
705 return PRESERVED_VALUE_P (v->val_rtx);
708 /* Arrange for a REG value to be assumed constant through the whole function,
709 never invalidated and preserved across cselib_reset_table calls. */
711 void
712 cselib_preserve_cfa_base_value (cselib_val *v, unsigned int regno)
714 if (cselib_preserve_constants
715 && v->locs
716 && REG_P (v->locs->loc))
718 cfa_base_preserved_val = v;
719 cfa_base_preserved_regno = regno;
723 /* Clean all non-constant expressions in the hash table, but retain
724 their values. */
726 void
727 cselib_preserve_only_values (void)
729 int i;
731 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
732 cselib_invalidate_regno (i, reg_raw_mode[i]);
734 cselib_invalidate_mem (callmem);
736 remove_useless_values ();
738 gcc_assert (first_containing_mem == &dummy_val);
741 /* Arrange for a value to be marked as based on stack pointer
742 for find_base_term purposes. */
744 void
745 cselib_set_value_sp_based (cselib_val *v)
747 SP_BASED_VALUE_P (v->val_rtx) = 1;
750 /* Test whether a value is based on stack pointer for
751 find_base_term purposes. */
753 bool
754 cselib_sp_based_value_p (cselib_val *v)
756 return SP_BASED_VALUE_P (v->val_rtx);
759 /* Return the mode in which a register was last set. If X is not a
760 register, return its mode. If the mode in which the register was
761 set is not known, or the value was already clobbered, return
762 VOIDmode. */
764 enum machine_mode
765 cselib_reg_set_mode (const_rtx x)
767 if (!REG_P (x))
768 return GET_MODE (x);
770 if (REG_VALUES (REGNO (x)) == NULL
771 || REG_VALUES (REGNO (x))->elt == NULL)
772 return VOIDmode;
774 return GET_MODE (REG_VALUES (REGNO (x))->elt->val_rtx);
777 /* Return nonzero if we can prove that X and Y contain the same value, taking
778 our gathered information into account. */
781 rtx_equal_for_cselib_p (rtx x, rtx y)
783 return rtx_equal_for_cselib_1 (x, y, VOIDmode);
786 /* If x is a PLUS or an autoinc operation, expand the operation,
787 storing the offset, if any, in *OFF. */
789 static rtx
790 autoinc_split (rtx x, rtx *off, enum machine_mode memmode)
792 switch (GET_CODE (x))
794 case PLUS:
795 *off = XEXP (x, 1);
796 return XEXP (x, 0);
798 case PRE_DEC:
799 if (memmode == VOIDmode)
800 return x;
802 *off = GEN_INT (-GET_MODE_SIZE (memmode));
803 return XEXP (x, 0);
804 break;
806 case PRE_INC:
807 if (memmode == VOIDmode)
808 return x;
810 *off = GEN_INT (GET_MODE_SIZE (memmode));
811 return XEXP (x, 0);
813 case PRE_MODIFY:
814 return XEXP (x, 1);
816 case POST_DEC:
817 case POST_INC:
818 case POST_MODIFY:
819 return XEXP (x, 0);
821 default:
822 return x;
826 /* Return nonzero if we can prove that X and Y contain the same value,
827 taking our gathered information into account. MEMMODE holds the
828 mode of the enclosing MEM, if any, as required to deal with autoinc
829 addressing modes. If X and Y are not (known to be) part of
830 addresses, MEMMODE should be VOIDmode. */
832 static int
833 rtx_equal_for_cselib_1 (rtx x, rtx y, enum machine_mode memmode)
835 enum rtx_code code;
836 const char *fmt;
837 int i;
839 if (REG_P (x) || MEM_P (x))
841 cselib_val *e = cselib_lookup (x, GET_MODE (x), 0, memmode);
843 if (e)
844 x = e->val_rtx;
847 if (REG_P (y) || MEM_P (y))
849 cselib_val *e = cselib_lookup (y, GET_MODE (y), 0, memmode);
851 if (e)
852 y = e->val_rtx;
855 if (x == y)
856 return 1;
858 if (GET_CODE (x) == VALUE)
860 cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (x));
861 struct elt_loc_list *l;
863 if (GET_CODE (y) == VALUE)
864 return e == canonical_cselib_val (CSELIB_VAL_PTR (y));
866 for (l = e->locs; l; l = l->next)
868 rtx t = l->loc;
870 /* Avoid infinite recursion. We know we have the canonical
871 value, so we can just skip any values in the equivalence
872 list. */
873 if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
874 continue;
875 else if (rtx_equal_for_cselib_1 (t, y, memmode))
876 return 1;
879 return 0;
881 else if (GET_CODE (y) == VALUE)
883 cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (y));
884 struct elt_loc_list *l;
886 for (l = e->locs; l; l = l->next)
888 rtx t = l->loc;
890 if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
891 continue;
892 else if (rtx_equal_for_cselib_1 (x, t, memmode))
893 return 1;
896 return 0;
899 if (GET_MODE (x) != GET_MODE (y))
900 return 0;
902 if (GET_CODE (x) != GET_CODE (y))
904 rtx xorig = x, yorig = y;
905 rtx xoff = NULL, yoff = NULL;
907 x = autoinc_split (x, &xoff, memmode);
908 y = autoinc_split (y, &yoff, memmode);
910 if (!xoff != !yoff)
911 return 0;
913 if (xoff && !rtx_equal_for_cselib_1 (xoff, yoff, memmode))
914 return 0;
916 /* Don't recurse if nothing changed. */
917 if (x != xorig || y != yorig)
918 return rtx_equal_for_cselib_1 (x, y, memmode);
920 return 0;
923 /* These won't be handled correctly by the code below. */
924 switch (GET_CODE (x))
926 case CONST_DOUBLE:
927 case CONST_FIXED:
928 case DEBUG_EXPR:
929 return 0;
931 case DEBUG_IMPLICIT_PTR:
932 return DEBUG_IMPLICIT_PTR_DECL (x)
933 == DEBUG_IMPLICIT_PTR_DECL (y);
935 case DEBUG_PARAMETER_REF:
936 return DEBUG_PARAMETER_REF_DECL (x)
937 == DEBUG_PARAMETER_REF_DECL (y);
939 case ENTRY_VALUE:
940 /* ENTRY_VALUEs are function invariant, it is thus undesirable to
941 use rtx_equal_for_cselib_1 to compare the operands. */
942 return rtx_equal_p (ENTRY_VALUE_EXP (x), ENTRY_VALUE_EXP (y));
944 case LABEL_REF:
945 return XEXP (x, 0) == XEXP (y, 0);
947 case MEM:
948 /* We have to compare any autoinc operations in the addresses
949 using this MEM's mode. */
950 return rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 0), GET_MODE (x));
952 default:
953 break;
956 code = GET_CODE (x);
957 fmt = GET_RTX_FORMAT (code);
959 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
961 int j;
963 switch (fmt[i])
965 case 'w':
966 if (XWINT (x, i) != XWINT (y, i))
967 return 0;
968 break;
970 case 'n':
971 case 'i':
972 if (XINT (x, i) != XINT (y, i))
973 return 0;
974 break;
976 case 'V':
977 case 'E':
978 /* Two vectors must have the same length. */
979 if (XVECLEN (x, i) != XVECLEN (y, i))
980 return 0;
982 /* And the corresponding elements must match. */
983 for (j = 0; j < XVECLEN (x, i); j++)
984 if (! rtx_equal_for_cselib_1 (XVECEXP (x, i, j),
985 XVECEXP (y, i, j), memmode))
986 return 0;
987 break;
989 case 'e':
990 if (i == 1
991 && targetm.commutative_p (x, UNKNOWN)
992 && rtx_equal_for_cselib_1 (XEXP (x, 1), XEXP (y, 0), memmode)
993 && rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 1), memmode))
994 return 1;
995 if (! rtx_equal_for_cselib_1 (XEXP (x, i), XEXP (y, i), memmode))
996 return 0;
997 break;
999 case 'S':
1000 case 's':
1001 if (strcmp (XSTR (x, i), XSTR (y, i)))
1002 return 0;
1003 break;
1005 case 'u':
1006 /* These are just backpointers, so they don't matter. */
1007 break;
1009 case '0':
1010 case 't':
1011 break;
1013 /* It is believed that rtx's at this level will never
1014 contain anything but integers and other rtx's,
1015 except for within LABEL_REFs and SYMBOL_REFs. */
1016 default:
1017 gcc_unreachable ();
1020 return 1;
1023 /* We need to pass down the mode of constants through the hash table
1024 functions. For that purpose, wrap them in a CONST of the appropriate
1025 mode. */
1026 static rtx
1027 wrap_constant (enum machine_mode mode, rtx x)
1029 if ((!CONST_SCALAR_INT_P (x)) && GET_CODE (x) != CONST_FIXED)
1030 return x;
1031 gcc_assert (mode != VOIDmode);
1032 return gen_rtx_CONST (mode, x);
1035 /* Hash an rtx. Return 0 if we couldn't hash the rtx.
1036 For registers and memory locations, we look up their cselib_val structure
1037 and return its VALUE element.
1038 Possible reasons for return 0 are: the object is volatile, or we couldn't
1039 find a register or memory location in the table and CREATE is zero. If
1040 CREATE is nonzero, table elts are created for regs and mem.
1041 N.B. this hash function returns the same hash value for RTXes that
1042 differ only in the order of operands, thus it is suitable for comparisons
1043 that take commutativity into account.
1044 If we wanted to also support associative rules, we'd have to use a different
1045 strategy to avoid returning spurious 0, e.g. return ~(~0U >> 1) .
1046 MEMMODE indicates the mode of an enclosing MEM, and it's only
1047 used to compute autoinc values.
1048 We used to have a MODE argument for hashing for CONST_INTs, but that
1049 didn't make sense, since it caused spurious hash differences between
1050 (set (reg:SI 1) (const_int))
1051 (plus:SI (reg:SI 2) (reg:SI 1))
1053 (plus:SI (reg:SI 2) (const_int))
1054 If the mode is important in any context, it must be checked specifically
1055 in a comparison anyway, since relying on hash differences is unsafe. */
1057 static unsigned int
1058 cselib_hash_rtx (rtx x, int create, enum machine_mode memmode)
1060 cselib_val *e;
1061 int i, j;
1062 enum rtx_code code;
1063 const char *fmt;
1064 unsigned int hash = 0;
1066 code = GET_CODE (x);
1067 hash += (unsigned) code + (unsigned) GET_MODE (x);
1069 switch (code)
1071 case VALUE:
1072 e = CSELIB_VAL_PTR (x);
1073 return e->hash;
1075 case MEM:
1076 case REG:
1077 e = cselib_lookup (x, GET_MODE (x), create, memmode);
1078 if (! e)
1079 return 0;
1081 return e->hash;
1083 case DEBUG_EXPR:
1084 hash += ((unsigned) DEBUG_EXPR << 7)
1085 + DEBUG_TEMP_UID (DEBUG_EXPR_TREE_DECL (x));
1086 return hash ? hash : (unsigned int) DEBUG_EXPR;
1088 case DEBUG_IMPLICIT_PTR:
1089 hash += ((unsigned) DEBUG_IMPLICIT_PTR << 7)
1090 + DECL_UID (DEBUG_IMPLICIT_PTR_DECL (x));
1091 return hash ? hash : (unsigned int) DEBUG_IMPLICIT_PTR;
1093 case DEBUG_PARAMETER_REF:
1094 hash += ((unsigned) DEBUG_PARAMETER_REF << 7)
1095 + DECL_UID (DEBUG_PARAMETER_REF_DECL (x));
1096 return hash ? hash : (unsigned int) DEBUG_PARAMETER_REF;
1098 case ENTRY_VALUE:
1099 /* ENTRY_VALUEs are function invariant, thus try to avoid
1100 recursing on argument if ENTRY_VALUE is one of the
1101 forms emitted by expand_debug_expr, otherwise
1102 ENTRY_VALUE hash would depend on the current value
1103 in some register or memory. */
1104 if (REG_P (ENTRY_VALUE_EXP (x)))
1105 hash += (unsigned int) REG
1106 + (unsigned int) GET_MODE (ENTRY_VALUE_EXP (x))
1107 + (unsigned int) REGNO (ENTRY_VALUE_EXP (x));
1108 else if (MEM_P (ENTRY_VALUE_EXP (x))
1109 && REG_P (XEXP (ENTRY_VALUE_EXP (x), 0)))
1110 hash += (unsigned int) MEM
1111 + (unsigned int) GET_MODE (XEXP (ENTRY_VALUE_EXP (x), 0))
1112 + (unsigned int) REGNO (XEXP (ENTRY_VALUE_EXP (x), 0));
1113 else
1114 hash += cselib_hash_rtx (ENTRY_VALUE_EXP (x), create, memmode);
1115 return hash ? hash : (unsigned int) ENTRY_VALUE;
1117 case CONST_INT:
1118 hash += ((unsigned) CONST_INT << 7) + INTVAL (x);
1119 return hash ? hash : (unsigned int) CONST_INT;
1121 case CONST_DOUBLE:
1122 /* This is like the general case, except that it only counts
1123 the integers representing the constant. */
1124 hash += (unsigned) code + (unsigned) GET_MODE (x);
1125 if (GET_MODE (x) != VOIDmode)
1126 hash += real_hash (CONST_DOUBLE_REAL_VALUE (x));
1127 else
1128 hash += ((unsigned) CONST_DOUBLE_LOW (x)
1129 + (unsigned) CONST_DOUBLE_HIGH (x));
1130 return hash ? hash : (unsigned int) CONST_DOUBLE;
1132 case CONST_FIXED:
1133 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1134 hash += fixed_hash (CONST_FIXED_VALUE (x));
1135 return hash ? hash : (unsigned int) CONST_FIXED;
1137 case CONST_VECTOR:
1139 int units;
1140 rtx elt;
1142 units = CONST_VECTOR_NUNITS (x);
1144 for (i = 0; i < units; ++i)
1146 elt = CONST_VECTOR_ELT (x, i);
1147 hash += cselib_hash_rtx (elt, 0, memmode);
1150 return hash;
1153 /* Assume there is only one rtx object for any given label. */
1154 case LABEL_REF:
1155 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1156 differences and differences between each stage's debugging dumps. */
1157 hash += (((unsigned int) LABEL_REF << 7)
1158 + CODE_LABEL_NUMBER (XEXP (x, 0)));
1159 return hash ? hash : (unsigned int) LABEL_REF;
1161 case SYMBOL_REF:
1163 /* Don't hash on the symbol's address to avoid bootstrap differences.
1164 Different hash values may cause expressions to be recorded in
1165 different orders and thus different registers to be used in the
1166 final assembler. This also avoids differences in the dump files
1167 between various stages. */
1168 unsigned int h = 0;
1169 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1171 while (*p)
1172 h += (h << 7) + *p++; /* ??? revisit */
1174 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1175 return hash ? hash : (unsigned int) SYMBOL_REF;
1178 case PRE_DEC:
1179 case PRE_INC:
1180 /* We can't compute these without knowing the MEM mode. */
1181 gcc_assert (memmode != VOIDmode);
1182 i = GET_MODE_SIZE (memmode);
1183 if (code == PRE_DEC)
1184 i = -i;
1185 /* Adjust the hash so that (mem:MEMMODE (pre_* (reg))) hashes
1186 like (mem:MEMMODE (plus (reg) (const_int I))). */
1187 hash += (unsigned) PLUS - (unsigned)code
1188 + cselib_hash_rtx (XEXP (x, 0), create, memmode)
1189 + cselib_hash_rtx (GEN_INT (i), create, memmode);
1190 return hash ? hash : 1 + (unsigned) PLUS;
1192 case PRE_MODIFY:
1193 gcc_assert (memmode != VOIDmode);
1194 return cselib_hash_rtx (XEXP (x, 1), create, memmode);
1196 case POST_DEC:
1197 case POST_INC:
1198 case POST_MODIFY:
1199 gcc_assert (memmode != VOIDmode);
1200 return cselib_hash_rtx (XEXP (x, 0), create, memmode);
1202 case PC:
1203 case CC0:
1204 case CALL:
1205 case UNSPEC_VOLATILE:
1206 return 0;
1208 case ASM_OPERANDS:
1209 if (MEM_VOLATILE_P (x))
1210 return 0;
1212 break;
1214 default:
1215 break;
1218 i = GET_RTX_LENGTH (code) - 1;
1219 fmt = GET_RTX_FORMAT (code);
1220 for (; i >= 0; i--)
1222 switch (fmt[i])
1224 case 'e':
1226 rtx tem = XEXP (x, i);
1227 unsigned int tem_hash = cselib_hash_rtx (tem, create, memmode);
1229 if (tem_hash == 0)
1230 return 0;
1232 hash += tem_hash;
1234 break;
1235 case 'E':
1236 for (j = 0; j < XVECLEN (x, i); j++)
1238 unsigned int tem_hash
1239 = cselib_hash_rtx (XVECEXP (x, i, j), create, memmode);
1241 if (tem_hash == 0)
1242 return 0;
1244 hash += tem_hash;
1246 break;
1248 case 's':
1250 const unsigned char *p = (const unsigned char *) XSTR (x, i);
1252 if (p)
1253 while (*p)
1254 hash += *p++;
1255 break;
1258 case 'i':
1259 hash += XINT (x, i);
1260 break;
1262 case '0':
1263 case 't':
1264 /* unused */
1265 break;
1267 default:
1268 gcc_unreachable ();
1272 return hash ? hash : 1 + (unsigned int) GET_CODE (x);
1275 /* Create a new value structure for VALUE and initialize it. The mode of the
1276 value is MODE. */
1278 static inline cselib_val *
1279 new_cselib_val (unsigned int hash, enum machine_mode mode, rtx x)
1281 cselib_val *e = (cselib_val *) pool_alloc (cselib_val_pool);
1283 gcc_assert (hash);
1284 gcc_assert (next_uid);
1286 e->hash = hash;
1287 e->uid = next_uid++;
1288 /* We use an alloc pool to allocate this RTL construct because it
1289 accounts for about 8% of the overall memory usage. We know
1290 precisely when we can have VALUE RTXen (when cselib is active)
1291 so we don't need to put them in garbage collected memory.
1292 ??? Why should a VALUE be an RTX in the first place? */
1293 e->val_rtx = (rtx) pool_alloc (value_pool);
1294 memset (e->val_rtx, 0, RTX_HDR_SIZE);
1295 PUT_CODE (e->val_rtx, VALUE);
1296 PUT_MODE (e->val_rtx, mode);
1297 CSELIB_VAL_PTR (e->val_rtx) = e;
1298 e->addr_list = 0;
1299 e->locs = 0;
1300 e->next_containing_mem = 0;
1302 if (dump_file && (dump_flags & TDF_CSELIB))
1304 fprintf (dump_file, "cselib value %u:%u ", e->uid, hash);
1305 if (flag_dump_noaddr || flag_dump_unnumbered)
1306 fputs ("# ", dump_file);
1307 else
1308 fprintf (dump_file, "%p ", (void*)e);
1309 print_rtl_single (dump_file, x);
1310 fputc ('\n', dump_file);
1313 return e;
1316 /* ADDR_ELT is a value that is used as address. MEM_ELT is the value that
1317 contains the data at this address. X is a MEM that represents the
1318 value. Update the two value structures to represent this situation. */
1320 static void
1321 add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x)
1323 struct elt_loc_list *l;
1325 addr_elt = canonical_cselib_val (addr_elt);
1326 mem_elt = canonical_cselib_val (mem_elt);
1328 /* Avoid duplicates. */
1329 for (l = mem_elt->locs; l; l = l->next)
1330 if (MEM_P (l->loc)
1331 && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt)
1333 promote_debug_loc (l);
1334 return;
1337 addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
1338 new_elt_loc_list (mem_elt,
1339 replace_equiv_address_nv (x, addr_elt->val_rtx));
1340 if (mem_elt->next_containing_mem == NULL)
1342 mem_elt->next_containing_mem = first_containing_mem;
1343 first_containing_mem = mem_elt;
1347 /* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx.
1348 If CREATE, make a new one if we haven't seen it before. */
1350 static cselib_val *
1351 cselib_lookup_mem (rtx x, int create)
1353 enum machine_mode mode = GET_MODE (x);
1354 enum machine_mode addr_mode;
1355 void **slot;
1356 cselib_val *addr;
1357 cselib_val *mem_elt;
1358 struct elt_list *l;
1360 if (MEM_VOLATILE_P (x) || mode == BLKmode
1361 || !cselib_record_memory
1362 || (FLOAT_MODE_P (mode) && flag_float_store))
1363 return 0;
1365 addr_mode = GET_MODE (XEXP (x, 0));
1366 if (addr_mode == VOIDmode)
1367 addr_mode = Pmode;
1369 /* Look up the value for the address. */
1370 addr = cselib_lookup (XEXP (x, 0), addr_mode, create, mode);
1371 if (! addr)
1372 return 0;
1374 addr = canonical_cselib_val (addr);
1375 /* Find a value that describes a value of our mode at that address. */
1376 for (l = addr->addr_list; l; l = l->next)
1377 if (GET_MODE (l->elt->val_rtx) == mode)
1379 promote_debug_loc (l->elt->locs);
1380 return l->elt;
1383 if (! create)
1384 return 0;
1386 mem_elt = new_cselib_val (next_uid, mode, x);
1387 add_mem_for_addr (addr, mem_elt, x);
1388 slot = cselib_find_slot (wrap_constant (mode, x), mem_elt->hash,
1389 INSERT, mode);
1390 *slot = mem_elt;
1391 return mem_elt;
1394 /* Search through the possible substitutions in P. We prefer a non reg
1395 substitution because this allows us to expand the tree further. If
1396 we find, just a reg, take the lowest regno. There may be several
1397 non-reg results, we just take the first one because they will all
1398 expand to the same place. */
1400 static rtx
1401 expand_loc (struct elt_loc_list *p, struct expand_value_data *evd,
1402 int max_depth)
1404 rtx reg_result = NULL;
1405 unsigned int regno = UINT_MAX;
1406 struct elt_loc_list *p_in = p;
1408 for (; p; p = p->next)
1410 /* Return these right away to avoid returning stack pointer based
1411 expressions for frame pointer and vice versa, which is something
1412 that would confuse DSE. See the comment in cselib_expand_value_rtx_1
1413 for more details. */
1414 if (REG_P (p->loc)
1415 && (REGNO (p->loc) == STACK_POINTER_REGNUM
1416 || REGNO (p->loc) == FRAME_POINTER_REGNUM
1417 || REGNO (p->loc) == HARD_FRAME_POINTER_REGNUM
1418 || REGNO (p->loc) == cfa_base_preserved_regno))
1419 return p->loc;
1420 /* Avoid infinite recursion trying to expand a reg into a
1421 the same reg. */
1422 if ((REG_P (p->loc))
1423 && (REGNO (p->loc) < regno)
1424 && !bitmap_bit_p (evd->regs_active, REGNO (p->loc)))
1426 reg_result = p->loc;
1427 regno = REGNO (p->loc);
1429 /* Avoid infinite recursion and do not try to expand the
1430 value. */
1431 else if (GET_CODE (p->loc) == VALUE
1432 && CSELIB_VAL_PTR (p->loc)->locs == p_in)
1433 continue;
1434 else if (!REG_P (p->loc))
1436 rtx result, note;
1437 if (dump_file && (dump_flags & TDF_CSELIB))
1439 print_inline_rtx (dump_file, p->loc, 0);
1440 fprintf (dump_file, "\n");
1442 if (GET_CODE (p->loc) == LO_SUM
1443 && GET_CODE (XEXP (p->loc, 1)) == SYMBOL_REF
1444 && p->setting_insn
1445 && (note = find_reg_note (p->setting_insn, REG_EQUAL, NULL_RTX))
1446 && XEXP (note, 0) == XEXP (p->loc, 1))
1447 return XEXP (p->loc, 1);
1448 result = cselib_expand_value_rtx_1 (p->loc, evd, max_depth - 1);
1449 if (result)
1450 return result;
1455 if (regno != UINT_MAX)
1457 rtx result;
1458 if (dump_file && (dump_flags & TDF_CSELIB))
1459 fprintf (dump_file, "r%d\n", regno);
1461 result = cselib_expand_value_rtx_1 (reg_result, evd, max_depth - 1);
1462 if (result)
1463 return result;
1466 if (dump_file && (dump_flags & TDF_CSELIB))
1468 if (reg_result)
1470 print_inline_rtx (dump_file, reg_result, 0);
1471 fprintf (dump_file, "\n");
1473 else
1474 fprintf (dump_file, "NULL\n");
1476 return reg_result;
1480 /* Forward substitute and expand an expression out to its roots.
1481 This is the opposite of common subexpression. Because local value
1482 numbering is such a weak optimization, the expanded expression is
1483 pretty much unique (not from a pointer equals point of view but
1484 from a tree shape point of view.
1486 This function returns NULL if the expansion fails. The expansion
1487 will fail if there is no value number for one of the operands or if
1488 one of the operands has been overwritten between the current insn
1489 and the beginning of the basic block. For instance x has no
1490 expansion in:
1492 r1 <- r1 + 3
1493 x <- r1 + 8
1495 REGS_ACTIVE is a scratch bitmap that should be clear when passing in.
1496 It is clear on return. */
1499 cselib_expand_value_rtx (rtx orig, bitmap regs_active, int max_depth)
1501 struct expand_value_data evd;
1503 evd.regs_active = regs_active;
1504 evd.callback = NULL;
1505 evd.callback_arg = NULL;
1506 evd.dummy = false;
1508 return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
1511 /* Same as cselib_expand_value_rtx, but using a callback to try to
1512 resolve some expressions. The CB function should return ORIG if it
1513 can't or does not want to deal with a certain RTX. Any other
1514 return value, including NULL, will be used as the expansion for
1515 VALUE, without any further changes. */
1518 cselib_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
1519 cselib_expand_callback cb, void *data)
1521 struct expand_value_data evd;
1523 evd.regs_active = regs_active;
1524 evd.callback = cb;
1525 evd.callback_arg = data;
1526 evd.dummy = false;
1528 return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
1531 /* Similar to cselib_expand_value_rtx_cb, but no rtxs are actually copied
1532 or simplified. Useful to find out whether cselib_expand_value_rtx_cb
1533 would return NULL or non-NULL, without allocating new rtx. */
1535 bool
1536 cselib_dummy_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
1537 cselib_expand_callback cb, void *data)
1539 struct expand_value_data evd;
1541 evd.regs_active = regs_active;
1542 evd.callback = cb;
1543 evd.callback_arg = data;
1544 evd.dummy = true;
1546 return cselib_expand_value_rtx_1 (orig, &evd, max_depth) != NULL;
1549 /* Internal implementation of cselib_expand_value_rtx and
1550 cselib_expand_value_rtx_cb. */
1552 static rtx
1553 cselib_expand_value_rtx_1 (rtx orig, struct expand_value_data *evd,
1554 int max_depth)
1556 rtx copy, scopy;
1557 int i, j;
1558 RTX_CODE code;
1559 const char *format_ptr;
1560 enum machine_mode mode;
1562 code = GET_CODE (orig);
1564 /* For the context of dse, if we end up expand into a huge tree, we
1565 will not have a useful address, so we might as well just give up
1566 quickly. */
1567 if (max_depth <= 0)
1568 return NULL;
1570 switch (code)
1572 case REG:
1574 struct elt_list *l = REG_VALUES (REGNO (orig));
1576 if (l && l->elt == NULL)
1577 l = l->next;
1578 for (; l; l = l->next)
1579 if (GET_MODE (l->elt->val_rtx) == GET_MODE (orig))
1581 rtx result;
1582 unsigned regno = REGNO (orig);
1584 /* The only thing that we are not willing to do (this
1585 is requirement of dse and if others potential uses
1586 need this function we should add a parm to control
1587 it) is that we will not substitute the
1588 STACK_POINTER_REGNUM, FRAME_POINTER or the
1589 HARD_FRAME_POINTER.
1591 These expansions confuses the code that notices that
1592 stores into the frame go dead at the end of the
1593 function and that the frame is not effected by calls
1594 to subroutines. If you allow the
1595 STACK_POINTER_REGNUM substitution, then dse will
1596 think that parameter pushing also goes dead which is
1597 wrong. If you allow the FRAME_POINTER or the
1598 HARD_FRAME_POINTER then you lose the opportunity to
1599 make the frame assumptions. */
1600 if (regno == STACK_POINTER_REGNUM
1601 || regno == FRAME_POINTER_REGNUM
1602 || regno == HARD_FRAME_POINTER_REGNUM
1603 || regno == cfa_base_preserved_regno)
1604 return orig;
1606 bitmap_set_bit (evd->regs_active, regno);
1608 if (dump_file && (dump_flags & TDF_CSELIB))
1609 fprintf (dump_file, "expanding: r%d into: ", regno);
1611 result = expand_loc (l->elt->locs, evd, max_depth);
1612 bitmap_clear_bit (evd->regs_active, regno);
1614 if (result)
1615 return result;
1616 else
1617 return orig;
1621 CASE_CONST_ANY:
1622 case SYMBOL_REF:
1623 case CODE_LABEL:
1624 case PC:
1625 case CC0:
1626 case SCRATCH:
1627 /* SCRATCH must be shared because they represent distinct values. */
1628 return orig;
1629 case CLOBBER:
1630 if (REG_P (XEXP (orig, 0)) && HARD_REGISTER_NUM_P (REGNO (XEXP (orig, 0))))
1631 return orig;
1632 break;
1634 case CONST:
1635 if (shared_const_p (orig))
1636 return orig;
1637 break;
1639 case SUBREG:
1641 rtx subreg;
1643 if (evd->callback)
1645 subreg = evd->callback (orig, evd->regs_active, max_depth,
1646 evd->callback_arg);
1647 if (subreg != orig)
1648 return subreg;
1651 subreg = cselib_expand_value_rtx_1 (SUBREG_REG (orig), evd,
1652 max_depth - 1);
1653 if (!subreg)
1654 return NULL;
1655 scopy = simplify_gen_subreg (GET_MODE (orig), subreg,
1656 GET_MODE (SUBREG_REG (orig)),
1657 SUBREG_BYTE (orig));
1658 if (scopy == NULL
1659 || (GET_CODE (scopy) == SUBREG
1660 && !REG_P (SUBREG_REG (scopy))
1661 && !MEM_P (SUBREG_REG (scopy))))
1662 return NULL;
1664 return scopy;
1667 case VALUE:
1669 rtx result;
1671 if (dump_file && (dump_flags & TDF_CSELIB))
1673 fputs ("\nexpanding ", dump_file);
1674 print_rtl_single (dump_file, orig);
1675 fputs (" into...", dump_file);
1678 if (evd->callback)
1680 result = evd->callback (orig, evd->regs_active, max_depth,
1681 evd->callback_arg);
1683 if (result != orig)
1684 return result;
1687 result = expand_loc (CSELIB_VAL_PTR (orig)->locs, evd, max_depth);
1688 return result;
1691 case DEBUG_EXPR:
1692 if (evd->callback)
1693 return evd->callback (orig, evd->regs_active, max_depth,
1694 evd->callback_arg);
1695 return orig;
1697 default:
1698 break;
1701 /* Copy the various flags, fields, and other information. We assume
1702 that all fields need copying, and then clear the fields that should
1703 not be copied. That is the sensible default behavior, and forces
1704 us to explicitly document why we are *not* copying a flag. */
1705 if (evd->dummy)
1706 copy = NULL;
1707 else
1708 copy = shallow_copy_rtx (orig);
1710 format_ptr = GET_RTX_FORMAT (code);
1712 for (i = 0; i < GET_RTX_LENGTH (code); i++)
1713 switch (*format_ptr++)
1715 case 'e':
1716 if (XEXP (orig, i) != NULL)
1718 rtx result = cselib_expand_value_rtx_1 (XEXP (orig, i), evd,
1719 max_depth - 1);
1720 if (!result)
1721 return NULL;
1722 if (copy)
1723 XEXP (copy, i) = result;
1725 break;
1727 case 'E':
1728 case 'V':
1729 if (XVEC (orig, i) != NULL)
1731 if (copy)
1732 XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i));
1733 for (j = 0; j < XVECLEN (orig, i); j++)
1735 rtx result = cselib_expand_value_rtx_1 (XVECEXP (orig, i, j),
1736 evd, max_depth - 1);
1737 if (!result)
1738 return NULL;
1739 if (copy)
1740 XVECEXP (copy, i, j) = result;
1743 break;
1745 case 't':
1746 case 'w':
1747 case 'i':
1748 case 's':
1749 case 'S':
1750 case 'T':
1751 case 'u':
1752 case 'B':
1753 case '0':
1754 /* These are left unchanged. */
1755 break;
1757 default:
1758 gcc_unreachable ();
1761 if (evd->dummy)
1762 return orig;
1764 mode = GET_MODE (copy);
1765 /* If an operand has been simplified into CONST_INT, which doesn't
1766 have a mode and the mode isn't derivable from whole rtx's mode,
1767 try simplify_*_operation first with mode from original's operand
1768 and as a fallback wrap CONST_INT into gen_rtx_CONST. */
1769 scopy = copy;
1770 switch (GET_RTX_CLASS (code))
1772 case RTX_UNARY:
1773 if (CONST_INT_P (XEXP (copy, 0))
1774 && GET_MODE (XEXP (orig, 0)) != VOIDmode)
1776 scopy = simplify_unary_operation (code, mode, XEXP (copy, 0),
1777 GET_MODE (XEXP (orig, 0)));
1778 if (scopy)
1779 return scopy;
1781 break;
1782 case RTX_COMM_ARITH:
1783 case RTX_BIN_ARITH:
1784 /* These expressions can derive operand modes from the whole rtx's mode. */
1785 break;
1786 case RTX_TERNARY:
1787 case RTX_BITFIELD_OPS:
1788 if (CONST_INT_P (XEXP (copy, 0))
1789 && GET_MODE (XEXP (orig, 0)) != VOIDmode)
1791 scopy = simplify_ternary_operation (code, mode,
1792 GET_MODE (XEXP (orig, 0)),
1793 XEXP (copy, 0), XEXP (copy, 1),
1794 XEXP (copy, 2));
1795 if (scopy)
1796 return scopy;
1798 break;
1799 case RTX_COMPARE:
1800 case RTX_COMM_COMPARE:
1801 if (CONST_INT_P (XEXP (copy, 0))
1802 && GET_MODE (XEXP (copy, 1)) == VOIDmode
1803 && (GET_MODE (XEXP (orig, 0)) != VOIDmode
1804 || GET_MODE (XEXP (orig, 1)) != VOIDmode))
1806 scopy = simplify_relational_operation (code, mode,
1807 (GET_MODE (XEXP (orig, 0))
1808 != VOIDmode)
1809 ? GET_MODE (XEXP (orig, 0))
1810 : GET_MODE (XEXP (orig, 1)),
1811 XEXP (copy, 0),
1812 XEXP (copy, 1));
1813 if (scopy)
1814 return scopy;
1816 break;
1817 default:
1818 break;
1820 scopy = simplify_rtx (copy);
1821 if (scopy)
1822 return scopy;
1823 return copy;
1826 /* Walk rtx X and replace all occurrences of REG and MEM subexpressions
1827 with VALUE expressions. This way, it becomes independent of changes
1828 to registers and memory.
1829 X isn't actually modified; if modifications are needed, new rtl is
1830 allocated. However, the return value can share rtl with X.
1831 If X is within a MEM, MEMMODE must be the mode of the MEM. */
1834 cselib_subst_to_values (rtx x, enum machine_mode memmode)
1836 enum rtx_code code = GET_CODE (x);
1837 const char *fmt = GET_RTX_FORMAT (code);
1838 cselib_val *e;
1839 struct elt_list *l;
1840 rtx copy = x;
1841 int i;
1843 switch (code)
1845 case REG:
1846 l = REG_VALUES (REGNO (x));
1847 if (l && l->elt == NULL)
1848 l = l->next;
1849 for (; l; l = l->next)
1850 if (GET_MODE (l->elt->val_rtx) == GET_MODE (x))
1851 return l->elt->val_rtx;
1853 gcc_unreachable ();
1855 case MEM:
1856 e = cselib_lookup_mem (x, 0);
1857 /* This used to happen for autoincrements, but we deal with them
1858 properly now. Remove the if stmt for the next release. */
1859 if (! e)
1861 /* Assign a value that doesn't match any other. */
1862 e = new_cselib_val (next_uid, GET_MODE (x), x);
1864 return e->val_rtx;
1866 case ENTRY_VALUE:
1867 e = cselib_lookup (x, GET_MODE (x), 0, memmode);
1868 if (! e)
1869 break;
1870 return e->val_rtx;
1872 CASE_CONST_ANY:
1873 return x;
1875 case PRE_DEC:
1876 case PRE_INC:
1877 gcc_assert (memmode != VOIDmode);
1878 i = GET_MODE_SIZE (memmode);
1879 if (code == PRE_DEC)
1880 i = -i;
1881 return cselib_subst_to_values (plus_constant (GET_MODE (x),
1882 XEXP (x, 0), i),
1883 memmode);
1885 case PRE_MODIFY:
1886 gcc_assert (memmode != VOIDmode);
1887 return cselib_subst_to_values (XEXP (x, 1), memmode);
1889 case POST_DEC:
1890 case POST_INC:
1891 case POST_MODIFY:
1892 gcc_assert (memmode != VOIDmode);
1893 return cselib_subst_to_values (XEXP (x, 0), memmode);
1895 default:
1896 break;
1899 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1901 if (fmt[i] == 'e')
1903 rtx t = cselib_subst_to_values (XEXP (x, i), memmode);
1905 if (t != XEXP (x, i))
1907 if (x == copy)
1908 copy = shallow_copy_rtx (x);
1909 XEXP (copy, i) = t;
1912 else if (fmt[i] == 'E')
1914 int j;
1916 for (j = 0; j < XVECLEN (x, i); j++)
1918 rtx t = cselib_subst_to_values (XVECEXP (x, i, j), memmode);
1920 if (t != XVECEXP (x, i, j))
1922 if (XVEC (x, i) == XVEC (copy, i))
1924 if (x == copy)
1925 copy = shallow_copy_rtx (x);
1926 XVEC (copy, i) = shallow_copy_rtvec (XVEC (x, i));
1928 XVECEXP (copy, i, j) = t;
1934 return copy;
1937 /* Wrapper for cselib_subst_to_values, that indicates X is in INSN. */
1940 cselib_subst_to_values_from_insn (rtx x, enum machine_mode memmode, rtx insn)
1942 rtx ret;
1943 gcc_assert (!cselib_current_insn);
1944 cselib_current_insn = insn;
1945 ret = cselib_subst_to_values (x, memmode);
1946 cselib_current_insn = NULL;
1947 return ret;
1950 /* Look up the rtl expression X in our tables and return the value it
1951 has. If CREATE is zero, we return NULL if we don't know the value.
1952 Otherwise, we create a new one if possible, using mode MODE if X
1953 doesn't have a mode (i.e. because it's a constant). When X is part
1954 of an address, MEMMODE should be the mode of the enclosing MEM if
1955 we're tracking autoinc expressions. */
1957 static cselib_val *
1958 cselib_lookup_1 (rtx x, enum machine_mode mode,
1959 int create, enum machine_mode memmode)
1961 void **slot;
1962 cselib_val *e;
1963 unsigned int hashval;
1965 if (GET_MODE (x) != VOIDmode)
1966 mode = GET_MODE (x);
1968 if (GET_CODE (x) == VALUE)
1969 return CSELIB_VAL_PTR (x);
1971 if (REG_P (x))
1973 struct elt_list *l;
1974 unsigned int i = REGNO (x);
1976 l = REG_VALUES (i);
1977 if (l && l->elt == NULL)
1978 l = l->next;
1979 for (; l; l = l->next)
1980 if (mode == GET_MODE (l->elt->val_rtx))
1982 promote_debug_loc (l->elt->locs);
1983 return l->elt;
1986 if (! create)
1987 return 0;
1989 if (i < FIRST_PSEUDO_REGISTER)
1991 unsigned int n = hard_regno_nregs[i][mode];
1993 if (n > max_value_regs)
1994 max_value_regs = n;
1997 e = new_cselib_val (next_uid, GET_MODE (x), x);
1998 new_elt_loc_list (e, x);
1999 if (REG_VALUES (i) == 0)
2001 /* Maintain the invariant that the first entry of
2002 REG_VALUES, if present, must be the value used to set the
2003 register, or NULL. */
2004 used_regs[n_used_regs++] = i;
2005 REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL);
2007 else if (cselib_preserve_constants
2008 && GET_MODE_CLASS (mode) == MODE_INT)
2010 /* During var-tracking, try harder to find equivalences
2011 for SUBREGs. If a setter sets say a DImode register
2012 and user uses that register only in SImode, add a lowpart
2013 subreg location. */
2014 struct elt_list *lwider = NULL;
2015 l = REG_VALUES (i);
2016 if (l && l->elt == NULL)
2017 l = l->next;
2018 for (; l; l = l->next)
2019 if (GET_MODE_CLASS (GET_MODE (l->elt->val_rtx)) == MODE_INT
2020 && GET_MODE_SIZE (GET_MODE (l->elt->val_rtx))
2021 > GET_MODE_SIZE (mode)
2022 && (lwider == NULL
2023 || GET_MODE_SIZE (GET_MODE (l->elt->val_rtx))
2024 < GET_MODE_SIZE (GET_MODE (lwider->elt->val_rtx))))
2026 struct elt_loc_list *el;
2027 if (i < FIRST_PSEUDO_REGISTER
2028 && hard_regno_nregs[i][GET_MODE (l->elt->val_rtx)] != 1)
2029 continue;
2030 for (el = l->elt->locs; el; el = el->next)
2031 if (!REG_P (el->loc))
2032 break;
2033 if (el)
2034 lwider = l;
2036 if (lwider)
2038 rtx sub = lowpart_subreg (mode, lwider->elt->val_rtx,
2039 GET_MODE (lwider->elt->val_rtx));
2040 if (sub)
2041 new_elt_loc_list (e, sub);
2044 REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e);
2045 slot = cselib_find_slot (x, e->hash, INSERT, memmode);
2046 *slot = e;
2047 return e;
2050 if (MEM_P (x))
2051 return cselib_lookup_mem (x, create);
2053 hashval = cselib_hash_rtx (x, create, memmode);
2054 /* Can't even create if hashing is not possible. */
2055 if (! hashval)
2056 return 0;
2058 slot = cselib_find_slot (wrap_constant (mode, x), hashval,
2059 create ? INSERT : NO_INSERT, memmode);
2060 if (slot == 0)
2061 return 0;
2063 e = (cselib_val *) *slot;
2064 if (e)
2065 return e;
2067 e = new_cselib_val (hashval, mode, x);
2069 /* We have to fill the slot before calling cselib_subst_to_values:
2070 the hash table is inconsistent until we do so, and
2071 cselib_subst_to_values will need to do lookups. */
2072 *slot = (void *) e;
2073 new_elt_loc_list (e, cselib_subst_to_values (x, memmode));
2074 return e;
2077 /* Wrapper for cselib_lookup, that indicates X is in INSN. */
2079 cselib_val *
2080 cselib_lookup_from_insn (rtx x, enum machine_mode mode,
2081 int create, enum machine_mode memmode, rtx insn)
2083 cselib_val *ret;
2085 gcc_assert (!cselib_current_insn);
2086 cselib_current_insn = insn;
2088 ret = cselib_lookup (x, mode, create, memmode);
2090 cselib_current_insn = NULL;
2092 return ret;
2095 /* Wrapper for cselib_lookup_1, that logs the lookup result and
2096 maintains invariants related with debug insns. */
2098 cselib_val *
2099 cselib_lookup (rtx x, enum machine_mode mode,
2100 int create, enum machine_mode memmode)
2102 cselib_val *ret = cselib_lookup_1 (x, mode, create, memmode);
2104 /* ??? Should we return NULL if we're not to create an entry, the
2105 found loc is a debug loc and cselib_current_insn is not DEBUG?
2106 If so, we should also avoid converting val to non-DEBUG; probably
2107 easiest setting cselib_current_insn to NULL before the call
2108 above. */
2110 if (dump_file && (dump_flags & TDF_CSELIB))
2112 fputs ("cselib lookup ", dump_file);
2113 print_inline_rtx (dump_file, x, 2);
2114 fprintf (dump_file, " => %u:%u\n",
2115 ret ? ret->uid : 0,
2116 ret ? ret->hash : 0);
2119 return ret;
2122 /* Invalidate any entries in reg_values that overlap REGNO. This is called
2123 if REGNO is changing. MODE is the mode of the assignment to REGNO, which
2124 is used to determine how many hard registers are being changed. If MODE
2125 is VOIDmode, then only REGNO is being changed; this is used when
2126 invalidating call clobbered registers across a call. */
2128 static void
2129 cselib_invalidate_regno (unsigned int regno, enum machine_mode mode)
2131 unsigned int endregno;
2132 unsigned int i;
2134 /* If we see pseudos after reload, something is _wrong_. */
2135 gcc_assert (!reload_completed || regno < FIRST_PSEUDO_REGISTER
2136 || reg_renumber[regno] < 0);
2138 /* Determine the range of registers that must be invalidated. For
2139 pseudos, only REGNO is affected. For hard regs, we must take MODE
2140 into account, and we must also invalidate lower register numbers
2141 if they contain values that overlap REGNO. */
2142 if (regno < FIRST_PSEUDO_REGISTER)
2144 gcc_assert (mode != VOIDmode);
2146 if (regno < max_value_regs)
2147 i = 0;
2148 else
2149 i = regno - max_value_regs;
2151 endregno = end_hard_regno (mode, regno);
2153 else
2155 i = regno;
2156 endregno = regno + 1;
2159 for (; i < endregno; i++)
2161 struct elt_list **l = &REG_VALUES (i);
2163 /* Go through all known values for this reg; if it overlaps the range
2164 we're invalidating, remove the value. */
2165 while (*l)
2167 cselib_val *v = (*l)->elt;
2168 bool had_locs;
2169 rtx setting_insn;
2170 struct elt_loc_list **p;
2171 unsigned int this_last = i;
2173 if (i < FIRST_PSEUDO_REGISTER && v != NULL)
2174 this_last = end_hard_regno (GET_MODE (v->val_rtx), i) - 1;
2176 if (this_last < regno || v == NULL
2177 || (v == cfa_base_preserved_val
2178 && i == cfa_base_preserved_regno))
2180 l = &(*l)->next;
2181 continue;
2184 /* We have an overlap. */
2185 if (*l == REG_VALUES (i))
2187 /* Maintain the invariant that the first entry of
2188 REG_VALUES, if present, must be the value used to set
2189 the register, or NULL. This is also nice because
2190 then we won't push the same regno onto user_regs
2191 multiple times. */
2192 (*l)->elt = NULL;
2193 l = &(*l)->next;
2195 else
2196 unchain_one_elt_list (l);
2198 v = canonical_cselib_val (v);
2200 had_locs = v->locs != NULL;
2201 setting_insn = v->locs ? v->locs->setting_insn : NULL;
2203 /* Now, we clear the mapping from value to reg. It must exist, so
2204 this code will crash intentionally if it doesn't. */
2205 for (p = &v->locs; ; p = &(*p)->next)
2207 rtx x = (*p)->loc;
2209 if (REG_P (x) && REGNO (x) == i)
2211 unchain_one_elt_loc_list (p);
2212 break;
2216 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
2218 if (setting_insn && DEBUG_INSN_P (setting_insn))
2219 n_useless_debug_values++;
2220 else
2221 n_useless_values++;
2227 /* Invalidate any locations in the table which are changed because of a
2228 store to MEM_RTX. If this is called because of a non-const call
2229 instruction, MEM_RTX is (mem:BLK const0_rtx). */
2231 static void
2232 cselib_invalidate_mem (rtx mem_rtx)
2234 cselib_val **vp, *v, *next;
2235 int num_mems = 0;
2236 rtx mem_addr;
2238 mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
2239 mem_rtx = canon_rtx (mem_rtx);
2241 vp = &first_containing_mem;
2242 for (v = *vp; v != &dummy_val; v = next)
2244 bool has_mem = false;
2245 struct elt_loc_list **p = &v->locs;
2246 bool had_locs = v->locs != NULL;
2247 rtx setting_insn = v->locs ? v->locs->setting_insn : NULL;
2249 while (*p)
2251 rtx x = (*p)->loc;
2252 cselib_val *addr;
2253 struct elt_list **mem_chain;
2255 /* MEMs may occur in locations only at the top level; below
2256 that every MEM or REG is substituted by its VALUE. */
2257 if (!MEM_P (x))
2259 p = &(*p)->next;
2260 continue;
2262 if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
2263 && ! canon_anti_dependence (x, false, mem_rtx,
2264 GET_MODE (mem_rtx), mem_addr))
2266 has_mem = true;
2267 num_mems++;
2268 p = &(*p)->next;
2269 continue;
2272 /* This one overlaps. */
2273 /* We must have a mapping from this MEM's address to the
2274 value (E). Remove that, too. */
2275 addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0, GET_MODE (x));
2276 addr = canonical_cselib_val (addr);
2277 gcc_checking_assert (v == canonical_cselib_val (v));
2278 mem_chain = &addr->addr_list;
2279 for (;;)
2281 cselib_val *canon = canonical_cselib_val ((*mem_chain)->elt);
2283 if (canon == v)
2285 unchain_one_elt_list (mem_chain);
2286 break;
2289 /* Record canonicalized elt. */
2290 (*mem_chain)->elt = canon;
2292 mem_chain = &(*mem_chain)->next;
2295 unchain_one_elt_loc_list (p);
2298 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
2300 if (setting_insn && DEBUG_INSN_P (setting_insn))
2301 n_useless_debug_values++;
2302 else
2303 n_useless_values++;
2306 next = v->next_containing_mem;
2307 if (has_mem)
2309 *vp = v;
2310 vp = &(*vp)->next_containing_mem;
2312 else
2313 v->next_containing_mem = NULL;
2315 *vp = &dummy_val;
2318 /* Invalidate DEST, which is being assigned to or clobbered. */
2320 void
2321 cselib_invalidate_rtx (rtx dest)
2323 while (GET_CODE (dest) == SUBREG
2324 || GET_CODE (dest) == ZERO_EXTRACT
2325 || GET_CODE (dest) == STRICT_LOW_PART)
2326 dest = XEXP (dest, 0);
2328 if (REG_P (dest))
2329 cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
2330 else if (MEM_P (dest))
2331 cselib_invalidate_mem (dest);
2334 /* A wrapper for cselib_invalidate_rtx to be called via note_stores. */
2336 static void
2337 cselib_invalidate_rtx_note_stores (rtx dest, const_rtx ignore ATTRIBUTE_UNUSED,
2338 void *data ATTRIBUTE_UNUSED)
2340 cselib_invalidate_rtx (dest);
2343 /* Record the result of a SET instruction. DEST is being set; the source
2344 contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT
2345 describes its address. */
2347 static void
2348 cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
2350 int dreg = REG_P (dest) ? (int) REGNO (dest) : -1;
2352 if (src_elt == 0 || side_effects_p (dest))
2353 return;
2355 if (dreg >= 0)
2357 if (dreg < FIRST_PSEUDO_REGISTER)
2359 unsigned int n = hard_regno_nregs[dreg][GET_MODE (dest)];
2361 if (n > max_value_regs)
2362 max_value_regs = n;
2365 if (REG_VALUES (dreg) == 0)
2367 used_regs[n_used_regs++] = dreg;
2368 REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
2370 else
2372 /* The register should have been invalidated. */
2373 gcc_assert (REG_VALUES (dreg)->elt == 0);
2374 REG_VALUES (dreg)->elt = src_elt;
2377 if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
2378 n_useless_values--;
2379 new_elt_loc_list (src_elt, dest);
2381 else if (MEM_P (dest) && dest_addr_elt != 0
2382 && cselib_record_memory)
2384 if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
2385 n_useless_values--;
2386 add_mem_for_addr (dest_addr_elt, src_elt, dest);
2390 /* Make ELT and X's VALUE equivalent to each other at INSN. */
2392 void
2393 cselib_add_permanent_equiv (cselib_val *elt, rtx x, rtx insn)
2395 cselib_val *nelt;
2396 rtx save_cselib_current_insn = cselib_current_insn;
2398 gcc_checking_assert (elt);
2399 gcc_checking_assert (PRESERVED_VALUE_P (elt->val_rtx));
2400 gcc_checking_assert (!side_effects_p (x));
2402 cselib_current_insn = insn;
2404 nelt = cselib_lookup (x, GET_MODE (elt->val_rtx), 1, VOIDmode);
2406 if (nelt != elt)
2408 cselib_any_perm_equivs = true;
2410 if (!PRESERVED_VALUE_P (nelt->val_rtx))
2411 cselib_preserve_value (nelt);
2413 new_elt_loc_list (nelt, elt->val_rtx);
2416 cselib_current_insn = save_cselib_current_insn;
2419 /* Return TRUE if any permanent equivalences have been recorded since
2420 the table was last initialized. */
2421 bool
2422 cselib_have_permanent_equivalences (void)
2424 return cselib_any_perm_equivs;
2427 /* There is no good way to determine how many elements there can be
2428 in a PARALLEL. Since it's fairly cheap, use a really large number. */
2429 #define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
2431 struct cselib_record_autoinc_data
2433 struct cselib_set *sets;
2434 int n_sets;
2437 /* Callback for for_each_inc_dec. Records in ARG the SETs implied by
2438 autoinc RTXs: SRC plus SRCOFF if non-NULL is stored in DEST. */
2440 static int
2441 cselib_record_autoinc_cb (rtx mem ATTRIBUTE_UNUSED, rtx op ATTRIBUTE_UNUSED,
2442 rtx dest, rtx src, rtx srcoff, void *arg)
2444 struct cselib_record_autoinc_data *data;
2445 data = (struct cselib_record_autoinc_data *)arg;
2447 data->sets[data->n_sets].dest = dest;
2449 if (srcoff)
2450 data->sets[data->n_sets].src = gen_rtx_PLUS (GET_MODE (src), src, srcoff);
2451 else
2452 data->sets[data->n_sets].src = src;
2454 data->n_sets++;
2456 return -1;
2459 /* Record the effects of any sets and autoincs in INSN. */
2460 static void
2461 cselib_record_sets (rtx insn)
2463 int n_sets = 0;
2464 int i;
2465 struct cselib_set sets[MAX_SETS];
2466 rtx body = PATTERN (insn);
2467 rtx cond = 0;
2468 int n_sets_before_autoinc;
2469 struct cselib_record_autoinc_data data;
2471 body = PATTERN (insn);
2472 if (GET_CODE (body) == COND_EXEC)
2474 cond = COND_EXEC_TEST (body);
2475 body = COND_EXEC_CODE (body);
2478 /* Find all sets. */
2479 if (GET_CODE (body) == SET)
2481 sets[0].src = SET_SRC (body);
2482 sets[0].dest = SET_DEST (body);
2483 n_sets = 1;
2485 else if (GET_CODE (body) == PARALLEL)
2487 /* Look through the PARALLEL and record the values being
2488 set, if possible. Also handle any CLOBBERs. */
2489 for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
2491 rtx x = XVECEXP (body, 0, i);
2493 if (GET_CODE (x) == SET)
2495 sets[n_sets].src = SET_SRC (x);
2496 sets[n_sets].dest = SET_DEST (x);
2497 n_sets++;
2502 if (n_sets == 1
2503 && MEM_P (sets[0].src)
2504 && !cselib_record_memory
2505 && MEM_READONLY_P (sets[0].src))
2507 rtx note = find_reg_equal_equiv_note (insn);
2509 if (note && CONSTANT_P (XEXP (note, 0)))
2510 sets[0].src = XEXP (note, 0);
2513 data.sets = sets;
2514 data.n_sets = n_sets_before_autoinc = n_sets;
2515 for_each_inc_dec (&insn, cselib_record_autoinc_cb, &data);
2516 n_sets = data.n_sets;
2518 /* Look up the values that are read. Do this before invalidating the
2519 locations that are written. */
2520 for (i = 0; i < n_sets; i++)
2522 rtx dest = sets[i].dest;
2524 /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
2525 the low part after invalidating any knowledge about larger modes. */
2526 if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
2527 sets[i].dest = dest = XEXP (dest, 0);
2529 /* We don't know how to record anything but REG or MEM. */
2530 if (REG_P (dest)
2531 || (MEM_P (dest) && cselib_record_memory))
2533 rtx src = sets[i].src;
2534 if (cond)
2535 src = gen_rtx_IF_THEN_ELSE (GET_MODE (dest), cond, src, dest);
2536 sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1, VOIDmode);
2537 if (MEM_P (dest))
2539 enum machine_mode address_mode = get_address_mode (dest);
2541 sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0),
2542 address_mode, 1,
2543 GET_MODE (dest));
2545 else
2546 sets[i].dest_addr_elt = 0;
2550 if (cselib_record_sets_hook)
2551 cselib_record_sets_hook (insn, sets, n_sets);
2553 /* Invalidate all locations written by this insn. Note that the elts we
2554 looked up in the previous loop aren't affected, just some of their
2555 locations may go away. */
2556 note_stores (body, cselib_invalidate_rtx_note_stores, NULL);
2558 for (i = n_sets_before_autoinc; i < n_sets; i++)
2559 cselib_invalidate_rtx (sets[i].dest);
2561 /* If this is an asm, look for duplicate sets. This can happen when the
2562 user uses the same value as an output multiple times. This is valid
2563 if the outputs are not actually used thereafter. Treat this case as
2564 if the value isn't actually set. We do this by smashing the destination
2565 to pc_rtx, so that we won't record the value later. */
2566 if (n_sets >= 2 && asm_noperands (body) >= 0)
2568 for (i = 0; i < n_sets; i++)
2570 rtx dest = sets[i].dest;
2571 if (REG_P (dest) || MEM_P (dest))
2573 int j;
2574 for (j = i + 1; j < n_sets; j++)
2575 if (rtx_equal_p (dest, sets[j].dest))
2577 sets[i].dest = pc_rtx;
2578 sets[j].dest = pc_rtx;
2584 /* Now enter the equivalences in our tables. */
2585 for (i = 0; i < n_sets; i++)
2587 rtx dest = sets[i].dest;
2588 if (REG_P (dest)
2589 || (MEM_P (dest) && cselib_record_memory))
2590 cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
2594 /* Return true if INSN in the prologue initializes hard_frame_pointer_rtx. */
2596 bool
2597 fp_setter_insn (rtx insn)
2599 rtx expr, pat = NULL_RTX;
2601 if (!RTX_FRAME_RELATED_P (insn))
2602 return false;
2604 expr = find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX);
2605 if (expr)
2606 pat = XEXP (expr, 0);
2607 if (!modified_in_p (hard_frame_pointer_rtx, pat ? pat : insn))
2608 return false;
2610 /* Don't return true for frame pointer restores in the epilogue. */
2611 if (find_reg_note (insn, REG_CFA_RESTORE, hard_frame_pointer_rtx))
2612 return false;
2613 return true;
2616 /* Record the effects of INSN. */
2618 void
2619 cselib_process_insn (rtx insn)
2621 int i;
2622 rtx x;
2624 cselib_current_insn = insn;
2626 /* Forget everything at a CODE_LABEL, a volatile insn, or a setjmp. */
2627 if ((LABEL_P (insn)
2628 || (CALL_P (insn)
2629 && find_reg_note (insn, REG_SETJMP, NULL))
2630 || (NONJUMP_INSN_P (insn)
2631 && volatile_insn_p (PATTERN (insn))))
2632 && !cselib_preserve_constants)
2634 cselib_reset_table (next_uid);
2635 cselib_current_insn = NULL_RTX;
2636 return;
2639 if (! INSN_P (insn))
2641 cselib_current_insn = NULL_RTX;
2642 return;
2645 /* If this is a call instruction, forget anything stored in a
2646 call clobbered register, or, if this is not a const call, in
2647 memory. */
2648 if (CALL_P (insn))
2650 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2651 if (call_used_regs[i]
2652 || (REG_VALUES (i) && REG_VALUES (i)->elt
2653 && HARD_REGNO_CALL_PART_CLOBBERED (i,
2654 GET_MODE (REG_VALUES (i)->elt->val_rtx))))
2655 cselib_invalidate_regno (i, reg_raw_mode[i]);
2657 /* Since it is not clear how cselib is going to be used, be
2658 conservative here and treat looping pure or const functions
2659 as if they were regular functions. */
2660 if (RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
2661 || !(RTL_CONST_OR_PURE_CALL_P (insn)))
2662 cselib_invalidate_mem (callmem);
2665 cselib_record_sets (insn);
2667 /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
2668 after we have processed the insn. */
2669 if (CALL_P (insn))
2671 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
2672 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
2673 cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0));
2674 /* Flush evertything on setjmp. */
2675 if (cselib_preserve_constants
2676 && find_reg_note (insn, REG_SETJMP, NULL))
2678 cselib_preserve_only_values ();
2679 cselib_reset_table (next_uid);
2683 /* On setter of the hard frame pointer if frame_pointer_needed,
2684 invalidate stack_pointer_rtx, so that sp and {,h}fp based
2685 VALUEs are distinct. */
2686 if (reload_completed
2687 && frame_pointer_needed
2688 && fp_setter_insn (insn))
2689 cselib_invalidate_rtx (stack_pointer_rtx);
2691 cselib_current_insn = NULL_RTX;
2693 if (n_useless_values > MAX_USELESS_VALUES
2694 /* remove_useless_values is linear in the hash table size. Avoid
2695 quadratic behavior for very large hashtables with very few
2696 useless elements. */
2697 && ((unsigned int)n_useless_values
2698 > (cselib_hash_table->n_elements
2699 - cselib_hash_table->n_deleted
2700 - n_debug_values) / 4))
2701 remove_useless_values ();
2704 /* Initialize cselib for one pass. The caller must also call
2705 init_alias_analysis. */
2707 void
2708 cselib_init (int record_what)
2710 elt_list_pool = create_alloc_pool ("elt_list",
2711 sizeof (struct elt_list), 10);
2712 elt_loc_list_pool = create_alloc_pool ("elt_loc_list",
2713 sizeof (struct elt_loc_list), 10);
2714 cselib_val_pool = create_alloc_pool ("cselib_val_list",
2715 sizeof (cselib_val), 10);
2716 value_pool = create_alloc_pool ("value", RTX_CODE_SIZE (VALUE), 100);
2717 cselib_record_memory = record_what & CSELIB_RECORD_MEMORY;
2718 cselib_preserve_constants = record_what & CSELIB_PRESERVE_CONSTANTS;
2719 cselib_any_perm_equivs = false;
2721 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything,
2722 see canon_true_dependence. This is only created once. */
2723 if (! callmem)
2724 callmem = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode));
2726 cselib_nregs = max_reg_num ();
2728 /* We preserve reg_values to allow expensive clearing of the whole thing.
2729 Reallocate it however if it happens to be too large. */
2730 if (!reg_values || reg_values_size < cselib_nregs
2731 || (reg_values_size > 10 && reg_values_size > cselib_nregs * 4))
2733 free (reg_values);
2734 /* Some space for newly emit instructions so we don't end up
2735 reallocating in between passes. */
2736 reg_values_size = cselib_nregs + (63 + cselib_nregs) / 16;
2737 reg_values = XCNEWVEC (struct elt_list *, reg_values_size);
2739 used_regs = XNEWVEC (unsigned int, cselib_nregs);
2740 n_used_regs = 0;
2741 cselib_hash_table = htab_create (31, get_value_hash,
2742 entry_and_rtx_equal_p, NULL);
2743 next_uid = 1;
2746 /* Called when the current user is done with cselib. */
2748 void
2749 cselib_finish (void)
2751 cselib_discard_hook = NULL;
2752 cselib_preserve_constants = false;
2753 cselib_any_perm_equivs = false;
2754 cfa_base_preserved_val = NULL;
2755 cfa_base_preserved_regno = INVALID_REGNUM;
2756 free_alloc_pool (elt_list_pool);
2757 free_alloc_pool (elt_loc_list_pool);
2758 free_alloc_pool (cselib_val_pool);
2759 free_alloc_pool (value_pool);
2760 cselib_clear_table ();
2761 htab_delete (cselib_hash_table);
2762 free (used_regs);
2763 used_regs = 0;
2764 cselib_hash_table = 0;
2765 n_useless_values = 0;
2766 n_useless_debug_values = 0;
2767 n_debug_values = 0;
2768 next_uid = 0;
2771 /* Dump the cselib_val *X to FILE *info. */
2773 static int
2774 dump_cselib_val (void **x, void *info)
2776 cselib_val *v = (cselib_val *)*x;
2777 FILE *out = (FILE *)info;
2778 bool need_lf = true;
2780 print_inline_rtx (out, v->val_rtx, 0);
2782 if (v->locs)
2784 struct elt_loc_list *l = v->locs;
2785 if (need_lf)
2787 fputc ('\n', out);
2788 need_lf = false;
2790 fputs (" locs:", out);
2793 if (l->setting_insn)
2794 fprintf (out, "\n from insn %i ",
2795 INSN_UID (l->setting_insn));
2796 else
2797 fprintf (out, "\n ");
2798 print_inline_rtx (out, l->loc, 4);
2800 while ((l = l->next));
2801 fputc ('\n', out);
2803 else
2805 fputs (" no locs", out);
2806 need_lf = true;
2809 if (v->addr_list)
2811 struct elt_list *e = v->addr_list;
2812 if (need_lf)
2814 fputc ('\n', out);
2815 need_lf = false;
2817 fputs (" addr list:", out);
2820 fputs ("\n ", out);
2821 print_inline_rtx (out, e->elt->val_rtx, 2);
2823 while ((e = e->next));
2824 fputc ('\n', out);
2826 else
2828 fputs (" no addrs", out);
2829 need_lf = true;
2832 if (v->next_containing_mem == &dummy_val)
2833 fputs (" last mem\n", out);
2834 else if (v->next_containing_mem)
2836 fputs (" next mem ", out);
2837 print_inline_rtx (out, v->next_containing_mem->val_rtx, 2);
2838 fputc ('\n', out);
2840 else if (need_lf)
2841 fputc ('\n', out);
2843 return 1;
2846 /* Dump to OUT everything in the CSELIB table. */
2848 void
2849 dump_cselib_table (FILE *out)
2851 fprintf (out, "cselib hash table:\n");
2852 htab_traverse (cselib_hash_table, dump_cselib_val, out);
2853 if (first_containing_mem != &dummy_val)
2855 fputs ("first mem ", out);
2856 print_inline_rtx (out, first_containing_mem->val_rtx, 2);
2857 fputc ('\n', out);
2859 fprintf (out, "next uid %i\n", next_uid);
2862 #include "gt-cselib.h"