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[official-gcc.git] / gcc / cselib.c
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1 /* Common subexpression elimination library for GNU compiler.
2 Copyright (C) 1987-2017 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 "backend.h"
24 #include "target.h"
25 #include "rtl.h"
26 #include "tree.h"
27 #include "df.h"
28 #include "memmodel.h"
29 #include "tm_p.h"
30 #include "regs.h"
31 #include "emit-rtl.h"
32 #include "dumpfile.h"
33 #include "cselib.h"
34 #include "params.h"
36 /* A list of cselib_val structures. */
37 struct elt_list
39 struct elt_list *next;
40 cselib_val *elt;
43 static bool cselib_record_memory;
44 static bool cselib_preserve_constants;
45 static bool cselib_any_perm_equivs;
46 static inline void promote_debug_loc (struct elt_loc_list *l);
47 static struct elt_list *new_elt_list (struct elt_list *, cselib_val *);
48 static void new_elt_loc_list (cselib_val *, rtx);
49 static void unchain_one_value (cselib_val *);
50 static void unchain_one_elt_list (struct elt_list **);
51 static void unchain_one_elt_loc_list (struct elt_loc_list **);
52 static void remove_useless_values (void);
53 static unsigned int cselib_hash_rtx (rtx, int, machine_mode);
54 static cselib_val *new_cselib_val (unsigned int, machine_mode, rtx);
55 static void add_mem_for_addr (cselib_val *, cselib_val *, rtx);
56 static cselib_val *cselib_lookup_mem (rtx, int);
57 static void cselib_invalidate_regno (unsigned int, machine_mode);
58 static void cselib_invalidate_mem (rtx);
59 static void cselib_record_set (rtx, cselib_val *, cselib_val *);
60 static void cselib_record_sets (rtx_insn *);
62 struct expand_value_data
64 bitmap regs_active;
65 cselib_expand_callback callback;
66 void *callback_arg;
67 bool dummy;
70 static rtx cselib_expand_value_rtx_1 (rtx, struct expand_value_data *, int);
72 /* There are three ways in which cselib can look up an rtx:
73 - for a REG, the reg_values table (which is indexed by regno) is used
74 - for a MEM, we recursively look up its address and then follow the
75 addr_list of that value
76 - for everything else, we compute a hash value and go through the hash
77 table. Since different rtx's can still have the same hash value,
78 this involves walking the table entries for a given value and comparing
79 the locations of the entries with the rtx we are looking up. */
81 struct cselib_hasher : nofree_ptr_hash <cselib_val>
83 struct key {
84 /* The rtx value and its mode (needed separately for constant
85 integers). */
86 machine_mode mode;
87 rtx x;
88 /* The mode of the contaning MEM, if any, otherwise VOIDmode. */
89 machine_mode memmode;
91 typedef key *compare_type;
92 static inline hashval_t hash (const cselib_val *);
93 static inline bool equal (const cselib_val *, const key *);
96 /* The hash function for our hash table. The value is always computed with
97 cselib_hash_rtx when adding an element; this function just extracts the
98 hash value from a cselib_val structure. */
100 inline hashval_t
101 cselib_hasher::hash (const cselib_val *v)
103 return v->hash;
106 /* The equality test for our hash table. The first argument V is a table
107 element (i.e. a cselib_val), while the second arg X is an rtx. We know
108 that all callers of htab_find_slot_with_hash will wrap CONST_INTs into a
109 CONST of an appropriate mode. */
111 inline bool
112 cselib_hasher::equal (const cselib_val *v, const key *x_arg)
114 struct elt_loc_list *l;
115 rtx x = x_arg->x;
116 machine_mode mode = x_arg->mode;
117 machine_mode memmode = x_arg->memmode;
119 if (mode != GET_MODE (v->val_rtx))
120 return false;
122 if (GET_CODE (x) == VALUE)
123 return x == v->val_rtx;
125 /* We don't guarantee that distinct rtx's have different hash values,
126 so we need to do a comparison. */
127 for (l = v->locs; l; l = l->next)
128 if (rtx_equal_for_cselib_1 (l->loc, x, memmode, 0))
130 promote_debug_loc (l);
131 return true;
134 return false;
137 /* A table that enables us to look up elts by their value. */
138 static hash_table<cselib_hasher> *cselib_hash_table;
140 /* A table to hold preserved values. */
141 static hash_table<cselib_hasher> *cselib_preserved_hash_table;
143 /* This is a global so we don't have to pass this through every function.
144 It is used in new_elt_loc_list to set SETTING_INSN. */
145 static rtx_insn *cselib_current_insn;
147 /* The unique id that the next create value will take. */
148 static unsigned int next_uid;
150 /* The number of registers we had when the varrays were last resized. */
151 static unsigned int cselib_nregs;
153 /* Count values without known locations, or with only locations that
154 wouldn't have been known except for debug insns. Whenever this
155 grows too big, we remove these useless values from the table.
157 Counting values with only debug values is a bit tricky. We don't
158 want to increment n_useless_values when we create a value for a
159 debug insn, for this would get n_useless_values out of sync, but we
160 want increment it if all locs in the list that were ever referenced
161 in nondebug insns are removed from the list.
163 In the general case, once we do that, we'd have to stop accepting
164 nondebug expressions in the loc list, to avoid having two values
165 equivalent that, without debug insns, would have been made into
166 separate values. However, because debug insns never introduce
167 equivalences themselves (no assignments), the only means for
168 growing loc lists is through nondebug assignments. If the locs
169 also happen to be referenced in debug insns, it will work just fine.
171 A consequence of this is that there's at most one debug-only loc in
172 each loc list. If we keep it in the first entry, testing whether
173 we have a debug-only loc list takes O(1).
175 Furthermore, since any additional entry in a loc list containing a
176 debug loc would have to come from an assignment (nondebug) that
177 references both the initial debug loc and the newly-equivalent loc,
178 the initial debug loc would be promoted to a nondebug loc, and the
179 loc list would not contain debug locs any more.
181 So the only case we have to be careful with in order to keep
182 n_useless_values in sync between debug and nondebug compilations is
183 to avoid incrementing n_useless_values when removing the single loc
184 from a value that turns out to not appear outside debug values. We
185 increment n_useless_debug_values instead, and leave such values
186 alone until, for other reasons, we garbage-collect useless
187 values. */
188 static int n_useless_values;
189 static int n_useless_debug_values;
191 /* Count values whose locs have been taken exclusively from debug
192 insns for the entire life of the value. */
193 static int n_debug_values;
195 /* Number of useless values before we remove them from the hash table. */
196 #define MAX_USELESS_VALUES 32
198 /* This table maps from register number to values. It does not
199 contain pointers to cselib_val structures, but rather elt_lists.
200 The purpose is to be able to refer to the same register in
201 different modes. The first element of the list defines the mode in
202 which the register was set; if the mode is unknown or the value is
203 no longer valid in that mode, ELT will be NULL for the first
204 element. */
205 static struct elt_list **reg_values;
206 static unsigned int reg_values_size;
207 #define REG_VALUES(i) reg_values[i]
209 /* The largest number of hard regs used by any entry added to the
210 REG_VALUES table. Cleared on each cselib_clear_table() invocation. */
211 static unsigned int max_value_regs;
213 /* Here the set of indices I with REG_VALUES(I) != 0 is saved. This is used
214 in cselib_clear_table() for fast emptying. */
215 static unsigned int *used_regs;
216 static unsigned int n_used_regs;
218 /* We pass this to cselib_invalidate_mem to invalidate all of
219 memory for a non-const call instruction. */
220 static GTY(()) rtx callmem;
222 /* Set by discard_useless_locs if it deleted the last location of any
223 value. */
224 static int values_became_useless;
226 /* Used as stop element of the containing_mem list so we can check
227 presence in the list by checking the next pointer. */
228 static cselib_val dummy_val;
230 /* If non-NULL, value of the eliminated arg_pointer_rtx or frame_pointer_rtx
231 that is constant through the whole function and should never be
232 eliminated. */
233 static cselib_val *cfa_base_preserved_val;
234 static unsigned int cfa_base_preserved_regno = INVALID_REGNUM;
236 /* Used to list all values that contain memory reference.
237 May or may not contain the useless values - the list is compacted
238 each time memory is invalidated. */
239 static cselib_val *first_containing_mem = &dummy_val;
241 static object_allocator<elt_list> elt_list_pool ("elt_list");
242 static object_allocator<elt_loc_list> elt_loc_list_pool ("elt_loc_list");
243 static object_allocator<cselib_val> cselib_val_pool ("cselib_val_list");
245 static pool_allocator value_pool ("value", RTX_CODE_SIZE (VALUE));
247 /* If nonnull, cselib will call this function before freeing useless
248 VALUEs. A VALUE is deemed useless if its "locs" field is null. */
249 void (*cselib_discard_hook) (cselib_val *);
251 /* If nonnull, cselib will call this function before recording sets or
252 even clobbering outputs of INSN. All the recorded sets will be
253 represented in the array sets[n_sets]. new_val_min can be used to
254 tell whether values present in sets are introduced by this
255 instruction. */
256 void (*cselib_record_sets_hook) (rtx_insn *insn, struct cselib_set *sets,
257 int n_sets);
259 #define PRESERVED_VALUE_P(RTX) \
260 (RTL_FLAG_CHECK1 ("PRESERVED_VALUE_P", (RTX), VALUE)->unchanging)
262 #define SP_BASED_VALUE_P(RTX) \
263 (RTL_FLAG_CHECK1 ("SP_BASED_VALUE_P", (RTX), VALUE)->jump)
267 /* Allocate a struct elt_list and fill in its two elements with the
268 arguments. */
270 static inline struct elt_list *
271 new_elt_list (struct elt_list *next, cselib_val *elt)
273 elt_list *el = elt_list_pool.allocate ();
274 el->next = next;
275 el->elt = elt;
276 return el;
279 /* Allocate a struct elt_loc_list with LOC and prepend it to VAL's loc
280 list. */
282 static inline void
283 new_elt_loc_list (cselib_val *val, rtx loc)
285 struct elt_loc_list *el, *next = val->locs;
287 gcc_checking_assert (!next || !next->setting_insn
288 || !DEBUG_INSN_P (next->setting_insn)
289 || cselib_current_insn == next->setting_insn);
291 /* If we're creating the first loc in a debug insn context, we've
292 just created a debug value. Count it. */
293 if (!next && cselib_current_insn && DEBUG_INSN_P (cselib_current_insn))
294 n_debug_values++;
296 val = canonical_cselib_val (val);
297 next = val->locs;
299 if (GET_CODE (loc) == VALUE)
301 loc = canonical_cselib_val (CSELIB_VAL_PTR (loc))->val_rtx;
303 gcc_checking_assert (PRESERVED_VALUE_P (loc)
304 == PRESERVED_VALUE_P (val->val_rtx));
306 if (val->val_rtx == loc)
307 return;
308 else if (val->uid > CSELIB_VAL_PTR (loc)->uid)
310 /* Reverse the insertion. */
311 new_elt_loc_list (CSELIB_VAL_PTR (loc), val->val_rtx);
312 return;
315 gcc_checking_assert (val->uid < CSELIB_VAL_PTR (loc)->uid);
317 if (CSELIB_VAL_PTR (loc)->locs)
319 /* Bring all locs from LOC to VAL. */
320 for (el = CSELIB_VAL_PTR (loc)->locs; el->next; el = el->next)
322 /* Adjust values that have LOC as canonical so that VAL
323 becomes their canonical. */
324 if (el->loc && GET_CODE (el->loc) == VALUE)
326 gcc_checking_assert (CSELIB_VAL_PTR (el->loc)->locs->loc
327 == loc);
328 CSELIB_VAL_PTR (el->loc)->locs->loc = val->val_rtx;
331 el->next = val->locs;
332 next = val->locs = CSELIB_VAL_PTR (loc)->locs;
335 if (CSELIB_VAL_PTR (loc)->addr_list)
337 /* Bring in addr_list into canonical node. */
338 struct elt_list *last = CSELIB_VAL_PTR (loc)->addr_list;
339 while (last->next)
340 last = last->next;
341 last->next = val->addr_list;
342 val->addr_list = CSELIB_VAL_PTR (loc)->addr_list;
343 CSELIB_VAL_PTR (loc)->addr_list = NULL;
346 if (CSELIB_VAL_PTR (loc)->next_containing_mem != NULL
347 && val->next_containing_mem == NULL)
349 /* Add VAL to the containing_mem list after LOC. LOC will
350 be removed when we notice it doesn't contain any
351 MEMs. */
352 val->next_containing_mem = CSELIB_VAL_PTR (loc)->next_containing_mem;
353 CSELIB_VAL_PTR (loc)->next_containing_mem = val;
356 /* Chain LOC back to VAL. */
357 el = elt_loc_list_pool.allocate ();
358 el->loc = val->val_rtx;
359 el->setting_insn = cselib_current_insn;
360 el->next = NULL;
361 CSELIB_VAL_PTR (loc)->locs = el;
364 el = elt_loc_list_pool.allocate ();
365 el->loc = loc;
366 el->setting_insn = cselib_current_insn;
367 el->next = next;
368 val->locs = el;
371 /* Promote loc L to a nondebug cselib_current_insn if L is marked as
372 originating from a debug insn, maintaining the debug values
373 count. */
375 static inline void
376 promote_debug_loc (struct elt_loc_list *l)
378 if (l && l->setting_insn && DEBUG_INSN_P (l->setting_insn)
379 && (!cselib_current_insn || !DEBUG_INSN_P (cselib_current_insn)))
381 n_debug_values--;
382 l->setting_insn = cselib_current_insn;
383 if (cselib_preserve_constants && l->next)
385 gcc_assert (l->next->setting_insn
386 && DEBUG_INSN_P (l->next->setting_insn)
387 && !l->next->next);
388 l->next->setting_insn = cselib_current_insn;
390 else
391 gcc_assert (!l->next);
395 /* The elt_list at *PL is no longer needed. Unchain it and free its
396 storage. */
398 static inline void
399 unchain_one_elt_list (struct elt_list **pl)
401 struct elt_list *l = *pl;
403 *pl = l->next;
404 elt_list_pool.remove (l);
407 /* Likewise for elt_loc_lists. */
409 static void
410 unchain_one_elt_loc_list (struct elt_loc_list **pl)
412 struct elt_loc_list *l = *pl;
414 *pl = l->next;
415 elt_loc_list_pool.remove (l);
418 /* Likewise for cselib_vals. This also frees the addr_list associated with
419 V. */
421 static void
422 unchain_one_value (cselib_val *v)
424 while (v->addr_list)
425 unchain_one_elt_list (&v->addr_list);
427 cselib_val_pool.remove (v);
430 /* Remove all entries from the hash table. Also used during
431 initialization. */
433 void
434 cselib_clear_table (void)
436 cselib_reset_table (1);
439 /* Return TRUE if V is a constant, a function invariant or a VALUE
440 equivalence; FALSE otherwise. */
442 static bool
443 invariant_or_equiv_p (cselib_val *v)
445 struct elt_loc_list *l;
447 if (v == cfa_base_preserved_val)
448 return true;
450 /* Keep VALUE equivalences around. */
451 for (l = v->locs; l; l = l->next)
452 if (GET_CODE (l->loc) == VALUE)
453 return true;
455 if (v->locs != NULL
456 && v->locs->next == NULL)
458 if (CONSTANT_P (v->locs->loc)
459 && (GET_CODE (v->locs->loc) != CONST
460 || !references_value_p (v->locs->loc, 0)))
461 return true;
462 /* Although a debug expr may be bound to different expressions,
463 we can preserve it as if it was constant, to get unification
464 and proper merging within var-tracking. */
465 if (GET_CODE (v->locs->loc) == DEBUG_EXPR
466 || GET_CODE (v->locs->loc) == DEBUG_IMPLICIT_PTR
467 || GET_CODE (v->locs->loc) == ENTRY_VALUE
468 || GET_CODE (v->locs->loc) == DEBUG_PARAMETER_REF)
469 return true;
471 /* (plus (value V) (const_int C)) is invariant iff V is invariant. */
472 if (GET_CODE (v->locs->loc) == PLUS
473 && CONST_INT_P (XEXP (v->locs->loc, 1))
474 && GET_CODE (XEXP (v->locs->loc, 0)) == VALUE
475 && invariant_or_equiv_p (CSELIB_VAL_PTR (XEXP (v->locs->loc, 0))))
476 return true;
479 return false;
482 /* Remove from hash table all VALUEs except constants, function
483 invariants and VALUE equivalences. */
486 preserve_constants_and_equivs (cselib_val **x, void *info ATTRIBUTE_UNUSED)
488 cselib_val *v = *x;
490 if (invariant_or_equiv_p (v))
492 cselib_hasher::key lookup = {
493 GET_MODE (v->val_rtx), v->val_rtx, VOIDmode
495 cselib_val **slot
496 = cselib_preserved_hash_table->find_slot_with_hash (&lookup,
497 v->hash, INSERT);
498 gcc_assert (!*slot);
499 *slot = v;
502 cselib_hash_table->clear_slot (x);
504 return 1;
507 /* Remove all entries from the hash table, arranging for the next
508 value to be numbered NUM. */
510 void
511 cselib_reset_table (unsigned int num)
513 unsigned int i;
515 max_value_regs = 0;
517 if (cfa_base_preserved_val)
519 unsigned int regno = cfa_base_preserved_regno;
520 unsigned int new_used_regs = 0;
521 for (i = 0; i < n_used_regs; i++)
522 if (used_regs[i] == regno)
524 new_used_regs = 1;
525 continue;
527 else
528 REG_VALUES (used_regs[i]) = 0;
529 gcc_assert (new_used_regs == 1);
530 n_used_regs = new_used_regs;
531 used_regs[0] = regno;
532 max_value_regs
533 = hard_regno_nregs[regno][GET_MODE (cfa_base_preserved_val->locs->loc)];
535 else
537 for (i = 0; i < n_used_regs; i++)
538 REG_VALUES (used_regs[i]) = 0;
539 n_used_regs = 0;
542 if (cselib_preserve_constants)
543 cselib_hash_table->traverse <void *, preserve_constants_and_equivs>
544 (NULL);
545 else
547 cselib_hash_table->empty ();
548 gcc_checking_assert (!cselib_any_perm_equivs);
551 n_useless_values = 0;
552 n_useless_debug_values = 0;
553 n_debug_values = 0;
555 next_uid = num;
557 first_containing_mem = &dummy_val;
560 /* Return the number of the next value that will be generated. */
562 unsigned int
563 cselib_get_next_uid (void)
565 return next_uid;
568 /* Search for X, whose hashcode is HASH, in CSELIB_HASH_TABLE,
569 INSERTing if requested. When X is part of the address of a MEM,
570 MEMMODE should specify the mode of the MEM. */
572 static cselib_val **
573 cselib_find_slot (machine_mode mode, rtx x, hashval_t hash,
574 enum insert_option insert, machine_mode memmode)
576 cselib_val **slot = NULL;
577 cselib_hasher::key lookup = { mode, x, memmode };
578 if (cselib_preserve_constants)
579 slot = cselib_preserved_hash_table->find_slot_with_hash (&lookup, hash,
580 NO_INSERT);
581 if (!slot)
582 slot = cselib_hash_table->find_slot_with_hash (&lookup, hash, insert);
583 return slot;
586 /* Return true if X contains a VALUE rtx. If ONLY_USELESS is set, we
587 only return true for values which point to a cselib_val whose value
588 element has been set to zero, which implies the cselib_val will be
589 removed. */
592 references_value_p (const_rtx x, int only_useless)
594 const enum rtx_code code = GET_CODE (x);
595 const char *fmt = GET_RTX_FORMAT (code);
596 int i, j;
598 if (GET_CODE (x) == VALUE
599 && (! only_useless ||
600 (CSELIB_VAL_PTR (x)->locs == 0 && !PRESERVED_VALUE_P (x))))
601 return 1;
603 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
605 if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless))
606 return 1;
607 else if (fmt[i] == 'E')
608 for (j = 0; j < XVECLEN (x, i); j++)
609 if (references_value_p (XVECEXP (x, i, j), only_useless))
610 return 1;
613 return 0;
616 /* For all locations found in X, delete locations that reference useless
617 values (i.e. values without any location). Called through
618 htab_traverse. */
621 discard_useless_locs (cselib_val **x, void *info ATTRIBUTE_UNUSED)
623 cselib_val *v = *x;
624 struct elt_loc_list **p = &v->locs;
625 bool had_locs = v->locs != NULL;
626 rtx_insn *setting_insn = v->locs ? v->locs->setting_insn : NULL;
628 while (*p)
630 if (references_value_p ((*p)->loc, 1))
631 unchain_one_elt_loc_list (p);
632 else
633 p = &(*p)->next;
636 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
638 if (setting_insn && DEBUG_INSN_P (setting_insn))
639 n_useless_debug_values++;
640 else
641 n_useless_values++;
642 values_became_useless = 1;
644 return 1;
647 /* If X is a value with no locations, remove it from the hashtable. */
650 discard_useless_values (cselib_val **x, void *info ATTRIBUTE_UNUSED)
652 cselib_val *v = *x;
654 if (v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
656 if (cselib_discard_hook)
657 cselib_discard_hook (v);
659 CSELIB_VAL_PTR (v->val_rtx) = NULL;
660 cselib_hash_table->clear_slot (x);
661 unchain_one_value (v);
662 n_useless_values--;
665 return 1;
668 /* Clean out useless values (i.e. those which no longer have locations
669 associated with them) from the hash table. */
671 static void
672 remove_useless_values (void)
674 cselib_val **p, *v;
676 /* First pass: eliminate locations that reference the value. That in
677 turn can make more values useless. */
680 values_became_useless = 0;
681 cselib_hash_table->traverse <void *, discard_useless_locs> (NULL);
683 while (values_became_useless);
685 /* Second pass: actually remove the values. */
687 p = &first_containing_mem;
688 for (v = *p; v != &dummy_val; v = v->next_containing_mem)
689 if (v->locs && v == canonical_cselib_val (v))
691 *p = v;
692 p = &(*p)->next_containing_mem;
694 *p = &dummy_val;
696 n_useless_values += n_useless_debug_values;
697 n_debug_values -= n_useless_debug_values;
698 n_useless_debug_values = 0;
700 cselib_hash_table->traverse <void *, discard_useless_values> (NULL);
702 gcc_assert (!n_useless_values);
705 /* Arrange for a value to not be removed from the hash table even if
706 it becomes useless. */
708 void
709 cselib_preserve_value (cselib_val *v)
711 PRESERVED_VALUE_P (v->val_rtx) = 1;
714 /* Test whether a value is preserved. */
716 bool
717 cselib_preserved_value_p (cselib_val *v)
719 return PRESERVED_VALUE_P (v->val_rtx);
722 /* Arrange for a REG value to be assumed constant through the whole function,
723 never invalidated and preserved across cselib_reset_table calls. */
725 void
726 cselib_preserve_cfa_base_value (cselib_val *v, unsigned int regno)
728 if (cselib_preserve_constants
729 && v->locs
730 && REG_P (v->locs->loc))
732 cfa_base_preserved_val = v;
733 cfa_base_preserved_regno = regno;
737 /* Clean all non-constant expressions in the hash table, but retain
738 their values. */
740 void
741 cselib_preserve_only_values (void)
743 int i;
745 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
746 cselib_invalidate_regno (i, reg_raw_mode[i]);
748 cselib_invalidate_mem (callmem);
750 remove_useless_values ();
752 gcc_assert (first_containing_mem == &dummy_val);
755 /* Arrange for a value to be marked as based on stack pointer
756 for find_base_term purposes. */
758 void
759 cselib_set_value_sp_based (cselib_val *v)
761 SP_BASED_VALUE_P (v->val_rtx) = 1;
764 /* Test whether a value is based on stack pointer for
765 find_base_term purposes. */
767 bool
768 cselib_sp_based_value_p (cselib_val *v)
770 return SP_BASED_VALUE_P (v->val_rtx);
773 /* Return the mode in which a register was last set. If X is not a
774 register, return its mode. If the mode in which the register was
775 set is not known, or the value was already clobbered, return
776 VOIDmode. */
778 machine_mode
779 cselib_reg_set_mode (const_rtx x)
781 if (!REG_P (x))
782 return GET_MODE (x);
784 if (REG_VALUES (REGNO (x)) == NULL
785 || REG_VALUES (REGNO (x))->elt == NULL)
786 return VOIDmode;
788 return GET_MODE (REG_VALUES (REGNO (x))->elt->val_rtx);
791 /* If x is a PLUS or an autoinc operation, expand the operation,
792 storing the offset, if any, in *OFF. */
794 static rtx
795 autoinc_split (rtx x, rtx *off, machine_mode memmode)
797 switch (GET_CODE (x))
799 case PLUS:
800 *off = XEXP (x, 1);
801 return XEXP (x, 0);
803 case PRE_DEC:
804 if (memmode == VOIDmode)
805 return x;
807 *off = GEN_INT (-GET_MODE_SIZE (memmode));
808 return XEXP (x, 0);
810 case PRE_INC:
811 if (memmode == VOIDmode)
812 return x;
814 *off = GEN_INT (GET_MODE_SIZE (memmode));
815 return XEXP (x, 0);
817 case PRE_MODIFY:
818 return XEXP (x, 1);
820 case POST_DEC:
821 case POST_INC:
822 case POST_MODIFY:
823 return XEXP (x, 0);
825 default:
826 return x;
830 /* Return nonzero if we can prove that X and Y contain the same value,
831 taking our gathered information into account. MEMMODE holds the
832 mode of the enclosing MEM, if any, as required to deal with autoinc
833 addressing modes. If X and Y are not (known to be) part of
834 addresses, MEMMODE should be VOIDmode. */
837 rtx_equal_for_cselib_1 (rtx x, rtx y, machine_mode memmode, int depth)
839 enum rtx_code code;
840 const char *fmt;
841 int i;
843 if (REG_P (x) || MEM_P (x))
845 cselib_val *e = cselib_lookup (x, GET_MODE (x), 0, memmode);
847 if (e)
848 x = e->val_rtx;
851 if (REG_P (y) || MEM_P (y))
853 cselib_val *e = cselib_lookup (y, GET_MODE (y), 0, memmode);
855 if (e)
856 y = e->val_rtx;
859 if (x == y)
860 return 1;
862 if (GET_CODE (x) == VALUE)
864 cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (x));
865 struct elt_loc_list *l;
867 if (GET_CODE (y) == VALUE)
868 return e == canonical_cselib_val (CSELIB_VAL_PTR (y));
870 if (depth == 128)
871 return 0;
873 for (l = e->locs; l; l = l->next)
875 rtx t = l->loc;
877 /* Avoid infinite recursion. We know we have the canonical
878 value, so we can just skip any values in the equivalence
879 list. */
880 if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
881 continue;
882 else if (rtx_equal_for_cselib_1 (t, y, memmode, depth + 1))
883 return 1;
886 return 0;
888 else if (GET_CODE (y) == VALUE)
890 cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (y));
891 struct elt_loc_list *l;
893 if (depth == 128)
894 return 0;
896 for (l = e->locs; l; l = l->next)
898 rtx t = l->loc;
900 if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
901 continue;
902 else if (rtx_equal_for_cselib_1 (x, t, memmode, depth + 1))
903 return 1;
906 return 0;
909 if (GET_MODE (x) != GET_MODE (y))
910 return 0;
912 if (GET_CODE (x) != GET_CODE (y))
914 rtx xorig = x, yorig = y;
915 rtx xoff = NULL, yoff = NULL;
917 x = autoinc_split (x, &xoff, memmode);
918 y = autoinc_split (y, &yoff, memmode);
920 if (!xoff != !yoff)
921 return 0;
923 if (xoff && !rtx_equal_for_cselib_1 (xoff, yoff, memmode, depth))
924 return 0;
926 /* Don't recurse if nothing changed. */
927 if (x != xorig || y != yorig)
928 return rtx_equal_for_cselib_1 (x, y, memmode, depth);
930 return 0;
933 /* These won't be handled correctly by the code below. */
934 switch (GET_CODE (x))
936 CASE_CONST_UNIQUE:
937 case DEBUG_EXPR:
938 return 0;
940 case DEBUG_IMPLICIT_PTR:
941 return DEBUG_IMPLICIT_PTR_DECL (x)
942 == DEBUG_IMPLICIT_PTR_DECL (y);
944 case DEBUG_PARAMETER_REF:
945 return DEBUG_PARAMETER_REF_DECL (x)
946 == DEBUG_PARAMETER_REF_DECL (y);
948 case ENTRY_VALUE:
949 /* ENTRY_VALUEs are function invariant, it is thus undesirable to
950 use rtx_equal_for_cselib_1 to compare the operands. */
951 return rtx_equal_p (ENTRY_VALUE_EXP (x), ENTRY_VALUE_EXP (y));
953 case LABEL_REF:
954 return label_ref_label (x) == label_ref_label (y);
956 case REG:
957 return REGNO (x) == REGNO (y);
959 case MEM:
960 /* We have to compare any autoinc operations in the addresses
961 using this MEM's mode. */
962 return rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 0), GET_MODE (x),
963 depth);
965 default:
966 break;
969 code = GET_CODE (x);
970 fmt = GET_RTX_FORMAT (code);
972 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
974 int j;
976 switch (fmt[i])
978 case 'w':
979 if (XWINT (x, i) != XWINT (y, i))
980 return 0;
981 break;
983 case 'n':
984 case 'i':
985 if (XINT (x, i) != XINT (y, i))
986 return 0;
987 break;
989 case 'V':
990 case 'E':
991 /* Two vectors must have the same length. */
992 if (XVECLEN (x, i) != XVECLEN (y, i))
993 return 0;
995 /* And the corresponding elements must match. */
996 for (j = 0; j < XVECLEN (x, i); j++)
997 if (! rtx_equal_for_cselib_1 (XVECEXP (x, i, j),
998 XVECEXP (y, i, j), memmode, depth))
999 return 0;
1000 break;
1002 case 'e':
1003 if (i == 1
1004 && targetm.commutative_p (x, UNKNOWN)
1005 && rtx_equal_for_cselib_1 (XEXP (x, 1), XEXP (y, 0), memmode,
1006 depth)
1007 && rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 1), memmode,
1008 depth))
1009 return 1;
1010 if (! rtx_equal_for_cselib_1 (XEXP (x, i), XEXP (y, i), memmode,
1011 depth))
1012 return 0;
1013 break;
1015 case 'S':
1016 case 's':
1017 if (strcmp (XSTR (x, i), XSTR (y, i)))
1018 return 0;
1019 break;
1021 case 'u':
1022 /* These are just backpointers, so they don't matter. */
1023 break;
1025 case '0':
1026 case 't':
1027 break;
1029 /* It is believed that rtx's at this level will never
1030 contain anything but integers and other rtx's,
1031 except for within LABEL_REFs and SYMBOL_REFs. */
1032 default:
1033 gcc_unreachable ();
1036 return 1;
1039 /* Hash an rtx. Return 0 if we couldn't hash the rtx.
1040 For registers and memory locations, we look up their cselib_val structure
1041 and return its VALUE element.
1042 Possible reasons for return 0 are: the object is volatile, or we couldn't
1043 find a register or memory location in the table and CREATE is zero. If
1044 CREATE is nonzero, table elts are created for regs and mem.
1045 N.B. this hash function returns the same hash value for RTXes that
1046 differ only in the order of operands, thus it is suitable for comparisons
1047 that take commutativity into account.
1048 If we wanted to also support associative rules, we'd have to use a different
1049 strategy to avoid returning spurious 0, e.g. return ~(~0U >> 1) .
1050 MEMMODE indicates the mode of an enclosing MEM, and it's only
1051 used to compute autoinc values.
1052 We used to have a MODE argument for hashing for CONST_INTs, but that
1053 didn't make sense, since it caused spurious hash differences between
1054 (set (reg:SI 1) (const_int))
1055 (plus:SI (reg:SI 2) (reg:SI 1))
1057 (plus:SI (reg:SI 2) (const_int))
1058 If the mode is important in any context, it must be checked specifically
1059 in a comparison anyway, since relying on hash differences is unsafe. */
1061 static unsigned int
1062 cselib_hash_rtx (rtx x, int create, machine_mode memmode)
1064 cselib_val *e;
1065 int i, j;
1066 enum rtx_code code;
1067 const char *fmt;
1068 unsigned int hash = 0;
1070 code = GET_CODE (x);
1071 hash += (unsigned) code + (unsigned) GET_MODE (x);
1073 switch (code)
1075 case VALUE:
1076 e = CSELIB_VAL_PTR (x);
1077 return e->hash;
1079 case MEM:
1080 case REG:
1081 e = cselib_lookup (x, GET_MODE (x), create, memmode);
1082 if (! e)
1083 return 0;
1085 return e->hash;
1087 case DEBUG_EXPR:
1088 hash += ((unsigned) DEBUG_EXPR << 7)
1089 + DEBUG_TEMP_UID (DEBUG_EXPR_TREE_DECL (x));
1090 return hash ? hash : (unsigned int) DEBUG_EXPR;
1092 case DEBUG_IMPLICIT_PTR:
1093 hash += ((unsigned) DEBUG_IMPLICIT_PTR << 7)
1094 + DECL_UID (DEBUG_IMPLICIT_PTR_DECL (x));
1095 return hash ? hash : (unsigned int) DEBUG_IMPLICIT_PTR;
1097 case DEBUG_PARAMETER_REF:
1098 hash += ((unsigned) DEBUG_PARAMETER_REF << 7)
1099 + DECL_UID (DEBUG_PARAMETER_REF_DECL (x));
1100 return hash ? hash : (unsigned int) DEBUG_PARAMETER_REF;
1102 case ENTRY_VALUE:
1103 /* ENTRY_VALUEs are function invariant, thus try to avoid
1104 recursing on argument if ENTRY_VALUE is one of the
1105 forms emitted by expand_debug_expr, otherwise
1106 ENTRY_VALUE hash would depend on the current value
1107 in some register or memory. */
1108 if (REG_P (ENTRY_VALUE_EXP (x)))
1109 hash += (unsigned int) REG
1110 + (unsigned int) GET_MODE (ENTRY_VALUE_EXP (x))
1111 + (unsigned int) REGNO (ENTRY_VALUE_EXP (x));
1112 else if (MEM_P (ENTRY_VALUE_EXP (x))
1113 && REG_P (XEXP (ENTRY_VALUE_EXP (x), 0)))
1114 hash += (unsigned int) MEM
1115 + (unsigned int) GET_MODE (XEXP (ENTRY_VALUE_EXP (x), 0))
1116 + (unsigned int) REGNO (XEXP (ENTRY_VALUE_EXP (x), 0));
1117 else
1118 hash += cselib_hash_rtx (ENTRY_VALUE_EXP (x), create, memmode);
1119 return hash ? hash : (unsigned int) ENTRY_VALUE;
1121 case CONST_INT:
1122 hash += ((unsigned) CONST_INT << 7) + UINTVAL (x);
1123 return hash ? hash : (unsigned int) CONST_INT;
1125 case CONST_WIDE_INT:
1126 for (i = 0; i < CONST_WIDE_INT_NUNITS (x); i++)
1127 hash += CONST_WIDE_INT_ELT (x, i);
1128 return hash;
1130 case CONST_DOUBLE:
1131 /* This is like the general case, except that it only counts
1132 the integers representing the constant. */
1133 hash += (unsigned) code + (unsigned) GET_MODE (x);
1134 if (TARGET_SUPPORTS_WIDE_INT == 0 && GET_MODE (x) == VOIDmode)
1135 hash += ((unsigned) CONST_DOUBLE_LOW (x)
1136 + (unsigned) CONST_DOUBLE_HIGH (x));
1137 else
1138 hash += real_hash (CONST_DOUBLE_REAL_VALUE (x));
1139 return hash ? hash : (unsigned int) CONST_DOUBLE;
1141 case CONST_FIXED:
1142 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1143 hash += fixed_hash (CONST_FIXED_VALUE (x));
1144 return hash ? hash : (unsigned int) CONST_FIXED;
1146 case CONST_VECTOR:
1148 int units;
1149 rtx elt;
1151 units = CONST_VECTOR_NUNITS (x);
1153 for (i = 0; i < units; ++i)
1155 elt = CONST_VECTOR_ELT (x, i);
1156 hash += cselib_hash_rtx (elt, 0, memmode);
1159 return hash;
1162 /* Assume there is only one rtx object for any given label. */
1163 case LABEL_REF:
1164 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1165 differences and differences between each stage's debugging dumps. */
1166 hash += (((unsigned int) LABEL_REF << 7)
1167 + CODE_LABEL_NUMBER (label_ref_label (x)));
1168 return hash ? hash : (unsigned int) LABEL_REF;
1170 case SYMBOL_REF:
1172 /* Don't hash on the symbol's address to avoid bootstrap differences.
1173 Different hash values may cause expressions to be recorded in
1174 different orders and thus different registers to be used in the
1175 final assembler. This also avoids differences in the dump files
1176 between various stages. */
1177 unsigned int h = 0;
1178 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1180 while (*p)
1181 h += (h << 7) + *p++; /* ??? revisit */
1183 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1184 return hash ? hash : (unsigned int) SYMBOL_REF;
1187 case PRE_DEC:
1188 case PRE_INC:
1189 /* We can't compute these without knowing the MEM mode. */
1190 gcc_assert (memmode != VOIDmode);
1191 i = GET_MODE_SIZE (memmode);
1192 if (code == PRE_DEC)
1193 i = -i;
1194 /* Adjust the hash so that (mem:MEMMODE (pre_* (reg))) hashes
1195 like (mem:MEMMODE (plus (reg) (const_int I))). */
1196 hash += (unsigned) PLUS - (unsigned)code
1197 + cselib_hash_rtx (XEXP (x, 0), create, memmode)
1198 + cselib_hash_rtx (GEN_INT (i), create, memmode);
1199 return hash ? hash : 1 + (unsigned) PLUS;
1201 case PRE_MODIFY:
1202 gcc_assert (memmode != VOIDmode);
1203 return cselib_hash_rtx (XEXP (x, 1), create, memmode);
1205 case POST_DEC:
1206 case POST_INC:
1207 case POST_MODIFY:
1208 gcc_assert (memmode != VOIDmode);
1209 return cselib_hash_rtx (XEXP (x, 0), create, memmode);
1211 case PC:
1212 case CC0:
1213 case CALL:
1214 case UNSPEC_VOLATILE:
1215 return 0;
1217 case ASM_OPERANDS:
1218 if (MEM_VOLATILE_P (x))
1219 return 0;
1221 break;
1223 default:
1224 break;
1227 i = GET_RTX_LENGTH (code) - 1;
1228 fmt = GET_RTX_FORMAT (code);
1229 for (; i >= 0; i--)
1231 switch (fmt[i])
1233 case 'e':
1235 rtx tem = XEXP (x, i);
1236 unsigned int tem_hash = cselib_hash_rtx (tem, create, memmode);
1238 if (tem_hash == 0)
1239 return 0;
1241 hash += tem_hash;
1243 break;
1244 case 'E':
1245 for (j = 0; j < XVECLEN (x, i); j++)
1247 unsigned int tem_hash
1248 = cselib_hash_rtx (XVECEXP (x, i, j), create, memmode);
1250 if (tem_hash == 0)
1251 return 0;
1253 hash += tem_hash;
1255 break;
1257 case 's':
1259 const unsigned char *p = (const unsigned char *) XSTR (x, i);
1261 if (p)
1262 while (*p)
1263 hash += *p++;
1264 break;
1267 case 'i':
1268 hash += XINT (x, i);
1269 break;
1271 case '0':
1272 case 't':
1273 /* unused */
1274 break;
1276 default:
1277 gcc_unreachable ();
1281 return hash ? hash : 1 + (unsigned int) GET_CODE (x);
1284 /* Create a new value structure for VALUE and initialize it. The mode of the
1285 value is MODE. */
1287 static inline cselib_val *
1288 new_cselib_val (unsigned int hash, machine_mode mode, rtx x)
1290 cselib_val *e = cselib_val_pool.allocate ();
1292 gcc_assert (hash);
1293 gcc_assert (next_uid);
1295 e->hash = hash;
1296 e->uid = next_uid++;
1297 /* We use an alloc pool to allocate this RTL construct because it
1298 accounts for about 8% of the overall memory usage. We know
1299 precisely when we can have VALUE RTXen (when cselib is active)
1300 so we don't need to put them in garbage collected memory.
1301 ??? Why should a VALUE be an RTX in the first place? */
1302 e->val_rtx = (rtx_def*) value_pool.allocate ();
1303 memset (e->val_rtx, 0, RTX_HDR_SIZE);
1304 PUT_CODE (e->val_rtx, VALUE);
1305 PUT_MODE (e->val_rtx, mode);
1306 CSELIB_VAL_PTR (e->val_rtx) = e;
1307 e->addr_list = 0;
1308 e->locs = 0;
1309 e->next_containing_mem = 0;
1311 if (dump_file && (dump_flags & TDF_CSELIB))
1313 fprintf (dump_file, "cselib value %u:%u ", e->uid, hash);
1314 if (flag_dump_noaddr || flag_dump_unnumbered)
1315 fputs ("# ", dump_file);
1316 else
1317 fprintf (dump_file, "%p ", (void*)e);
1318 print_rtl_single (dump_file, x);
1319 fputc ('\n', dump_file);
1322 return e;
1325 /* ADDR_ELT is a value that is used as address. MEM_ELT is the value that
1326 contains the data at this address. X is a MEM that represents the
1327 value. Update the two value structures to represent this situation. */
1329 static void
1330 add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x)
1332 addr_elt = canonical_cselib_val (addr_elt);
1333 mem_elt = canonical_cselib_val (mem_elt);
1335 /* Avoid duplicates. */
1336 addr_space_t as = MEM_ADDR_SPACE (x);
1337 for (elt_loc_list *l = mem_elt->locs; l; l = l->next)
1338 if (MEM_P (l->loc)
1339 && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt
1340 && MEM_ADDR_SPACE (l->loc) == as)
1342 promote_debug_loc (l);
1343 return;
1346 addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
1347 new_elt_loc_list (mem_elt,
1348 replace_equiv_address_nv (x, addr_elt->val_rtx));
1349 if (mem_elt->next_containing_mem == NULL)
1351 mem_elt->next_containing_mem = first_containing_mem;
1352 first_containing_mem = mem_elt;
1356 /* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx.
1357 If CREATE, make a new one if we haven't seen it before. */
1359 static cselib_val *
1360 cselib_lookup_mem (rtx x, int create)
1362 machine_mode mode = GET_MODE (x);
1363 machine_mode addr_mode;
1364 cselib_val **slot;
1365 cselib_val *addr;
1366 cselib_val *mem_elt;
1368 if (MEM_VOLATILE_P (x) || mode == BLKmode
1369 || !cselib_record_memory
1370 || (FLOAT_MODE_P (mode) && flag_float_store))
1371 return 0;
1373 addr_mode = GET_MODE (XEXP (x, 0));
1374 if (addr_mode == VOIDmode)
1375 addr_mode = Pmode;
1377 /* Look up the value for the address. */
1378 addr = cselib_lookup (XEXP (x, 0), addr_mode, create, mode);
1379 if (! addr)
1380 return 0;
1381 addr = canonical_cselib_val (addr);
1383 /* Find a value that describes a value of our mode at that address. */
1384 addr_space_t as = MEM_ADDR_SPACE (x);
1385 for (elt_list *l = addr->addr_list; l; l = l->next)
1386 if (GET_MODE (l->elt->val_rtx) == mode)
1388 for (elt_loc_list *l2 = l->elt->locs; l2; l2 = l2->next)
1389 if (MEM_P (l2->loc) && MEM_ADDR_SPACE (l2->loc) == as)
1391 promote_debug_loc (l->elt->locs);
1392 return l->elt;
1396 if (! create)
1397 return 0;
1399 mem_elt = new_cselib_val (next_uid, mode, x);
1400 add_mem_for_addr (addr, mem_elt, x);
1401 slot = cselib_find_slot (mode, x, mem_elt->hash, INSERT, VOIDmode);
1402 *slot = mem_elt;
1403 return mem_elt;
1406 /* Search through the possible substitutions in P. We prefer a non reg
1407 substitution because this allows us to expand the tree further. If
1408 we find, just a reg, take the lowest regno. There may be several
1409 non-reg results, we just take the first one because they will all
1410 expand to the same place. */
1412 static rtx
1413 expand_loc (struct elt_loc_list *p, struct expand_value_data *evd,
1414 int max_depth)
1416 rtx reg_result = NULL;
1417 unsigned int regno = UINT_MAX;
1418 struct elt_loc_list *p_in = p;
1420 for (; p; p = p->next)
1422 /* Return these right away to avoid returning stack pointer based
1423 expressions for frame pointer and vice versa, which is something
1424 that would confuse DSE. See the comment in cselib_expand_value_rtx_1
1425 for more details. */
1426 if (REG_P (p->loc)
1427 && (REGNO (p->loc) == STACK_POINTER_REGNUM
1428 || REGNO (p->loc) == FRAME_POINTER_REGNUM
1429 || REGNO (p->loc) == HARD_FRAME_POINTER_REGNUM
1430 || REGNO (p->loc) == cfa_base_preserved_regno))
1431 return p->loc;
1432 /* Avoid infinite recursion trying to expand a reg into a
1433 the same reg. */
1434 if ((REG_P (p->loc))
1435 && (REGNO (p->loc) < regno)
1436 && !bitmap_bit_p (evd->regs_active, REGNO (p->loc)))
1438 reg_result = p->loc;
1439 regno = REGNO (p->loc);
1441 /* Avoid infinite recursion and do not try to expand the
1442 value. */
1443 else if (GET_CODE (p->loc) == VALUE
1444 && CSELIB_VAL_PTR (p->loc)->locs == p_in)
1445 continue;
1446 else if (!REG_P (p->loc))
1448 rtx result, note;
1449 if (dump_file && (dump_flags & TDF_CSELIB))
1451 print_inline_rtx (dump_file, p->loc, 0);
1452 fprintf (dump_file, "\n");
1454 if (GET_CODE (p->loc) == LO_SUM
1455 && GET_CODE (XEXP (p->loc, 1)) == SYMBOL_REF
1456 && p->setting_insn
1457 && (note = find_reg_note (p->setting_insn, REG_EQUAL, NULL_RTX))
1458 && XEXP (note, 0) == XEXP (p->loc, 1))
1459 return XEXP (p->loc, 1);
1460 result = cselib_expand_value_rtx_1 (p->loc, evd, max_depth - 1);
1461 if (result)
1462 return result;
1467 if (regno != UINT_MAX)
1469 rtx result;
1470 if (dump_file && (dump_flags & TDF_CSELIB))
1471 fprintf (dump_file, "r%d\n", regno);
1473 result = cselib_expand_value_rtx_1 (reg_result, evd, max_depth - 1);
1474 if (result)
1475 return result;
1478 if (dump_file && (dump_flags & TDF_CSELIB))
1480 if (reg_result)
1482 print_inline_rtx (dump_file, reg_result, 0);
1483 fprintf (dump_file, "\n");
1485 else
1486 fprintf (dump_file, "NULL\n");
1488 return reg_result;
1492 /* Forward substitute and expand an expression out to its roots.
1493 This is the opposite of common subexpression. Because local value
1494 numbering is such a weak optimization, the expanded expression is
1495 pretty much unique (not from a pointer equals point of view but
1496 from a tree shape point of view.
1498 This function returns NULL if the expansion fails. The expansion
1499 will fail if there is no value number for one of the operands or if
1500 one of the operands has been overwritten between the current insn
1501 and the beginning of the basic block. For instance x has no
1502 expansion in:
1504 r1 <- r1 + 3
1505 x <- r1 + 8
1507 REGS_ACTIVE is a scratch bitmap that should be clear when passing in.
1508 It is clear on return. */
1511 cselib_expand_value_rtx (rtx orig, bitmap regs_active, int max_depth)
1513 struct expand_value_data evd;
1515 evd.regs_active = regs_active;
1516 evd.callback = NULL;
1517 evd.callback_arg = NULL;
1518 evd.dummy = false;
1520 return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
1523 /* Same as cselib_expand_value_rtx, but using a callback to try to
1524 resolve some expressions. The CB function should return ORIG if it
1525 can't or does not want to deal with a certain RTX. Any other
1526 return value, including NULL, will be used as the expansion for
1527 VALUE, without any further changes. */
1530 cselib_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
1531 cselib_expand_callback cb, void *data)
1533 struct expand_value_data evd;
1535 evd.regs_active = regs_active;
1536 evd.callback = cb;
1537 evd.callback_arg = data;
1538 evd.dummy = false;
1540 return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
1543 /* Similar to cselib_expand_value_rtx_cb, but no rtxs are actually copied
1544 or simplified. Useful to find out whether cselib_expand_value_rtx_cb
1545 would return NULL or non-NULL, without allocating new rtx. */
1547 bool
1548 cselib_dummy_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
1549 cselib_expand_callback cb, void *data)
1551 struct expand_value_data evd;
1553 evd.regs_active = regs_active;
1554 evd.callback = cb;
1555 evd.callback_arg = data;
1556 evd.dummy = true;
1558 return cselib_expand_value_rtx_1 (orig, &evd, max_depth) != NULL;
1561 /* Internal implementation of cselib_expand_value_rtx and
1562 cselib_expand_value_rtx_cb. */
1564 static rtx
1565 cselib_expand_value_rtx_1 (rtx orig, struct expand_value_data *evd,
1566 int max_depth)
1568 rtx copy, scopy;
1569 int i, j;
1570 RTX_CODE code;
1571 const char *format_ptr;
1572 machine_mode mode;
1574 code = GET_CODE (orig);
1576 /* For the context of dse, if we end up expand into a huge tree, we
1577 will not have a useful address, so we might as well just give up
1578 quickly. */
1579 if (max_depth <= 0)
1580 return NULL;
1582 switch (code)
1584 case REG:
1586 struct elt_list *l = REG_VALUES (REGNO (orig));
1588 if (l && l->elt == NULL)
1589 l = l->next;
1590 for (; l; l = l->next)
1591 if (GET_MODE (l->elt->val_rtx) == GET_MODE (orig))
1593 rtx result;
1594 unsigned regno = REGNO (orig);
1596 /* The only thing that we are not willing to do (this
1597 is requirement of dse and if others potential uses
1598 need this function we should add a parm to control
1599 it) is that we will not substitute the
1600 STACK_POINTER_REGNUM, FRAME_POINTER or the
1601 HARD_FRAME_POINTER.
1603 These expansions confuses the code that notices that
1604 stores into the frame go dead at the end of the
1605 function and that the frame is not effected by calls
1606 to subroutines. If you allow the
1607 STACK_POINTER_REGNUM substitution, then dse will
1608 think that parameter pushing also goes dead which is
1609 wrong. If you allow the FRAME_POINTER or the
1610 HARD_FRAME_POINTER then you lose the opportunity to
1611 make the frame assumptions. */
1612 if (regno == STACK_POINTER_REGNUM
1613 || regno == FRAME_POINTER_REGNUM
1614 || regno == HARD_FRAME_POINTER_REGNUM
1615 || regno == cfa_base_preserved_regno)
1616 return orig;
1618 bitmap_set_bit (evd->regs_active, regno);
1620 if (dump_file && (dump_flags & TDF_CSELIB))
1621 fprintf (dump_file, "expanding: r%d into: ", regno);
1623 result = expand_loc (l->elt->locs, evd, max_depth);
1624 bitmap_clear_bit (evd->regs_active, regno);
1626 if (result)
1627 return result;
1628 else
1629 return orig;
1631 return orig;
1634 CASE_CONST_ANY:
1635 case SYMBOL_REF:
1636 case CODE_LABEL:
1637 case PC:
1638 case CC0:
1639 case SCRATCH:
1640 /* SCRATCH must be shared because they represent distinct values. */
1641 return orig;
1642 case CLOBBER:
1643 if (REG_P (XEXP (orig, 0)) && HARD_REGISTER_NUM_P (REGNO (XEXP (orig, 0))))
1644 return orig;
1645 break;
1647 case CONST:
1648 if (shared_const_p (orig))
1649 return orig;
1650 break;
1652 case SUBREG:
1654 rtx subreg;
1656 if (evd->callback)
1658 subreg = evd->callback (orig, evd->regs_active, max_depth,
1659 evd->callback_arg);
1660 if (subreg != orig)
1661 return subreg;
1664 subreg = cselib_expand_value_rtx_1 (SUBREG_REG (orig), evd,
1665 max_depth - 1);
1666 if (!subreg)
1667 return NULL;
1668 scopy = simplify_gen_subreg (GET_MODE (orig), subreg,
1669 GET_MODE (SUBREG_REG (orig)),
1670 SUBREG_BYTE (orig));
1671 if (scopy == NULL
1672 || (GET_CODE (scopy) == SUBREG
1673 && !REG_P (SUBREG_REG (scopy))
1674 && !MEM_P (SUBREG_REG (scopy))))
1675 return NULL;
1677 return scopy;
1680 case VALUE:
1682 rtx result;
1684 if (dump_file && (dump_flags & TDF_CSELIB))
1686 fputs ("\nexpanding ", dump_file);
1687 print_rtl_single (dump_file, orig);
1688 fputs (" into...", dump_file);
1691 if (evd->callback)
1693 result = evd->callback (orig, evd->regs_active, max_depth,
1694 evd->callback_arg);
1696 if (result != orig)
1697 return result;
1700 result = expand_loc (CSELIB_VAL_PTR (orig)->locs, evd, max_depth);
1701 return result;
1704 case DEBUG_EXPR:
1705 if (evd->callback)
1706 return evd->callback (orig, evd->regs_active, max_depth,
1707 evd->callback_arg);
1708 return orig;
1710 default:
1711 break;
1714 /* Copy the various flags, fields, and other information. We assume
1715 that all fields need copying, and then clear the fields that should
1716 not be copied. That is the sensible default behavior, and forces
1717 us to explicitly document why we are *not* copying a flag. */
1718 if (evd->dummy)
1719 copy = NULL;
1720 else
1721 copy = shallow_copy_rtx (orig);
1723 format_ptr = GET_RTX_FORMAT (code);
1725 for (i = 0; i < GET_RTX_LENGTH (code); i++)
1726 switch (*format_ptr++)
1728 case 'e':
1729 if (XEXP (orig, i) != NULL)
1731 rtx result = cselib_expand_value_rtx_1 (XEXP (orig, i), evd,
1732 max_depth - 1);
1733 if (!result)
1734 return NULL;
1735 if (copy)
1736 XEXP (copy, i) = result;
1738 break;
1740 case 'E':
1741 case 'V':
1742 if (XVEC (orig, i) != NULL)
1744 if (copy)
1745 XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i));
1746 for (j = 0; j < XVECLEN (orig, i); j++)
1748 rtx result = cselib_expand_value_rtx_1 (XVECEXP (orig, i, j),
1749 evd, max_depth - 1);
1750 if (!result)
1751 return NULL;
1752 if (copy)
1753 XVECEXP (copy, i, j) = result;
1756 break;
1758 case 't':
1759 case 'w':
1760 case 'i':
1761 case 's':
1762 case 'S':
1763 case 'T':
1764 case 'u':
1765 case 'B':
1766 case '0':
1767 /* These are left unchanged. */
1768 break;
1770 default:
1771 gcc_unreachable ();
1774 if (evd->dummy)
1775 return orig;
1777 mode = GET_MODE (copy);
1778 /* If an operand has been simplified into CONST_INT, which doesn't
1779 have a mode and the mode isn't derivable from whole rtx's mode,
1780 try simplify_*_operation first with mode from original's operand
1781 and as a fallback wrap CONST_INT into gen_rtx_CONST. */
1782 scopy = copy;
1783 switch (GET_RTX_CLASS (code))
1785 case RTX_UNARY:
1786 if (CONST_INT_P (XEXP (copy, 0))
1787 && GET_MODE (XEXP (orig, 0)) != VOIDmode)
1789 scopy = simplify_unary_operation (code, mode, XEXP (copy, 0),
1790 GET_MODE (XEXP (orig, 0)));
1791 if (scopy)
1792 return scopy;
1794 break;
1795 case RTX_COMM_ARITH:
1796 case RTX_BIN_ARITH:
1797 /* These expressions can derive operand modes from the whole rtx's mode. */
1798 break;
1799 case RTX_TERNARY:
1800 case RTX_BITFIELD_OPS:
1801 if (CONST_INT_P (XEXP (copy, 0))
1802 && GET_MODE (XEXP (orig, 0)) != VOIDmode)
1804 scopy = simplify_ternary_operation (code, mode,
1805 GET_MODE (XEXP (orig, 0)),
1806 XEXP (copy, 0), XEXP (copy, 1),
1807 XEXP (copy, 2));
1808 if (scopy)
1809 return scopy;
1811 break;
1812 case RTX_COMPARE:
1813 case RTX_COMM_COMPARE:
1814 if (CONST_INT_P (XEXP (copy, 0))
1815 && GET_MODE (XEXP (copy, 1)) == VOIDmode
1816 && (GET_MODE (XEXP (orig, 0)) != VOIDmode
1817 || GET_MODE (XEXP (orig, 1)) != VOIDmode))
1819 scopy = simplify_relational_operation (code, mode,
1820 (GET_MODE (XEXP (orig, 0))
1821 != VOIDmode)
1822 ? GET_MODE (XEXP (orig, 0))
1823 : GET_MODE (XEXP (orig, 1)),
1824 XEXP (copy, 0),
1825 XEXP (copy, 1));
1826 if (scopy)
1827 return scopy;
1829 break;
1830 default:
1831 break;
1833 scopy = simplify_rtx (copy);
1834 if (scopy)
1835 return scopy;
1836 return copy;
1839 /* Walk rtx X and replace all occurrences of REG and MEM subexpressions
1840 with VALUE expressions. This way, it becomes independent of changes
1841 to registers and memory.
1842 X isn't actually modified; if modifications are needed, new rtl is
1843 allocated. However, the return value can share rtl with X.
1844 If X is within a MEM, MEMMODE must be the mode of the MEM. */
1847 cselib_subst_to_values (rtx x, machine_mode memmode)
1849 enum rtx_code code = GET_CODE (x);
1850 const char *fmt = GET_RTX_FORMAT (code);
1851 cselib_val *e;
1852 struct elt_list *l;
1853 rtx copy = x;
1854 int i;
1856 switch (code)
1858 case REG:
1859 l = REG_VALUES (REGNO (x));
1860 if (l && l->elt == NULL)
1861 l = l->next;
1862 for (; l; l = l->next)
1863 if (GET_MODE (l->elt->val_rtx) == GET_MODE (x))
1864 return l->elt->val_rtx;
1866 gcc_unreachable ();
1868 case MEM:
1869 e = cselib_lookup_mem (x, 0);
1870 /* This used to happen for autoincrements, but we deal with them
1871 properly now. Remove the if stmt for the next release. */
1872 if (! e)
1874 /* Assign a value that doesn't match any other. */
1875 e = new_cselib_val (next_uid, GET_MODE (x), x);
1877 return e->val_rtx;
1879 case ENTRY_VALUE:
1880 e = cselib_lookup (x, GET_MODE (x), 0, memmode);
1881 if (! e)
1882 break;
1883 return e->val_rtx;
1885 CASE_CONST_ANY:
1886 return x;
1888 case PRE_DEC:
1889 case PRE_INC:
1890 gcc_assert (memmode != VOIDmode);
1891 i = GET_MODE_SIZE (memmode);
1892 if (code == PRE_DEC)
1893 i = -i;
1894 return cselib_subst_to_values (plus_constant (GET_MODE (x),
1895 XEXP (x, 0), i),
1896 memmode);
1898 case PRE_MODIFY:
1899 gcc_assert (memmode != VOIDmode);
1900 return cselib_subst_to_values (XEXP (x, 1), memmode);
1902 case POST_DEC:
1903 case POST_INC:
1904 case POST_MODIFY:
1905 gcc_assert (memmode != VOIDmode);
1906 return cselib_subst_to_values (XEXP (x, 0), memmode);
1908 default:
1909 break;
1912 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1914 if (fmt[i] == 'e')
1916 rtx t = cselib_subst_to_values (XEXP (x, i), memmode);
1918 if (t != XEXP (x, i))
1920 if (x == copy)
1921 copy = shallow_copy_rtx (x);
1922 XEXP (copy, i) = t;
1925 else if (fmt[i] == 'E')
1927 int j;
1929 for (j = 0; j < XVECLEN (x, i); j++)
1931 rtx t = cselib_subst_to_values (XVECEXP (x, i, j), memmode);
1933 if (t != XVECEXP (x, i, j))
1935 if (XVEC (x, i) == XVEC (copy, i))
1937 if (x == copy)
1938 copy = shallow_copy_rtx (x);
1939 XVEC (copy, i) = shallow_copy_rtvec (XVEC (x, i));
1941 XVECEXP (copy, i, j) = t;
1947 return copy;
1950 /* Wrapper for cselib_subst_to_values, that indicates X is in INSN. */
1953 cselib_subst_to_values_from_insn (rtx x, machine_mode memmode, rtx_insn *insn)
1955 rtx ret;
1956 gcc_assert (!cselib_current_insn);
1957 cselib_current_insn = insn;
1958 ret = cselib_subst_to_values (x, memmode);
1959 cselib_current_insn = NULL;
1960 return ret;
1963 /* Look up the rtl expression X in our tables and return the value it
1964 has. If CREATE is zero, we return NULL if we don't know the value.
1965 Otherwise, we create a new one if possible, using mode MODE if X
1966 doesn't have a mode (i.e. because it's a constant). When X is part
1967 of an address, MEMMODE should be the mode of the enclosing MEM if
1968 we're tracking autoinc expressions. */
1970 static cselib_val *
1971 cselib_lookup_1 (rtx x, machine_mode mode,
1972 int create, machine_mode memmode)
1974 cselib_val **slot;
1975 cselib_val *e;
1976 unsigned int hashval;
1978 if (GET_MODE (x) != VOIDmode)
1979 mode = GET_MODE (x);
1981 if (GET_CODE (x) == VALUE)
1982 return CSELIB_VAL_PTR (x);
1984 if (REG_P (x))
1986 struct elt_list *l;
1987 unsigned int i = REGNO (x);
1989 l = REG_VALUES (i);
1990 if (l && l->elt == NULL)
1991 l = l->next;
1992 for (; l; l = l->next)
1993 if (mode == GET_MODE (l->elt->val_rtx))
1995 promote_debug_loc (l->elt->locs);
1996 return l->elt;
1999 if (! create)
2000 return 0;
2002 if (i < FIRST_PSEUDO_REGISTER)
2004 unsigned int n = hard_regno_nregs[i][mode];
2006 if (n > max_value_regs)
2007 max_value_regs = n;
2010 e = new_cselib_val (next_uid, GET_MODE (x), x);
2011 new_elt_loc_list (e, x);
2012 if (REG_VALUES (i) == 0)
2014 /* Maintain the invariant that the first entry of
2015 REG_VALUES, if present, must be the value used to set the
2016 register, or NULL. */
2017 used_regs[n_used_regs++] = i;
2018 REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL);
2020 else if (cselib_preserve_constants
2021 && GET_MODE_CLASS (mode) == MODE_INT)
2023 /* During var-tracking, try harder to find equivalences
2024 for SUBREGs. If a setter sets say a DImode register
2025 and user uses that register only in SImode, add a lowpart
2026 subreg location. */
2027 struct elt_list *lwider = NULL;
2028 l = REG_VALUES (i);
2029 if (l && l->elt == NULL)
2030 l = l->next;
2031 for (; l; l = l->next)
2032 if (GET_MODE_CLASS (GET_MODE (l->elt->val_rtx)) == MODE_INT
2033 && GET_MODE_SIZE (GET_MODE (l->elt->val_rtx))
2034 > GET_MODE_SIZE (mode)
2035 && (lwider == NULL
2036 || GET_MODE_SIZE (GET_MODE (l->elt->val_rtx))
2037 < GET_MODE_SIZE (GET_MODE (lwider->elt->val_rtx))))
2039 struct elt_loc_list *el;
2040 if (i < FIRST_PSEUDO_REGISTER
2041 && hard_regno_nregs[i][GET_MODE (l->elt->val_rtx)] != 1)
2042 continue;
2043 for (el = l->elt->locs; el; el = el->next)
2044 if (!REG_P (el->loc))
2045 break;
2046 if (el)
2047 lwider = l;
2049 if (lwider)
2051 rtx sub = lowpart_subreg (mode, lwider->elt->val_rtx,
2052 GET_MODE (lwider->elt->val_rtx));
2053 if (sub)
2054 new_elt_loc_list (e, sub);
2057 REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e);
2058 slot = cselib_find_slot (mode, x, e->hash, INSERT, memmode);
2059 *slot = e;
2060 return e;
2063 if (MEM_P (x))
2064 return cselib_lookup_mem (x, create);
2066 hashval = cselib_hash_rtx (x, create, memmode);
2067 /* Can't even create if hashing is not possible. */
2068 if (! hashval)
2069 return 0;
2071 slot = cselib_find_slot (mode, x, hashval,
2072 create ? INSERT : NO_INSERT, memmode);
2073 if (slot == 0)
2074 return 0;
2076 e = (cselib_val *) *slot;
2077 if (e)
2078 return e;
2080 e = new_cselib_val (hashval, mode, x);
2082 /* We have to fill the slot before calling cselib_subst_to_values:
2083 the hash table is inconsistent until we do so, and
2084 cselib_subst_to_values will need to do lookups. */
2085 *slot = e;
2086 new_elt_loc_list (e, cselib_subst_to_values (x, memmode));
2087 return e;
2090 /* Wrapper for cselib_lookup, that indicates X is in INSN. */
2092 cselib_val *
2093 cselib_lookup_from_insn (rtx x, machine_mode mode,
2094 int create, machine_mode memmode, rtx_insn *insn)
2096 cselib_val *ret;
2098 gcc_assert (!cselib_current_insn);
2099 cselib_current_insn = insn;
2101 ret = cselib_lookup (x, mode, create, memmode);
2103 cselib_current_insn = NULL;
2105 return ret;
2108 /* Wrapper for cselib_lookup_1, that logs the lookup result and
2109 maintains invariants related with debug insns. */
2111 cselib_val *
2112 cselib_lookup (rtx x, machine_mode mode,
2113 int create, machine_mode memmode)
2115 cselib_val *ret = cselib_lookup_1 (x, mode, create, memmode);
2117 /* ??? Should we return NULL if we're not to create an entry, the
2118 found loc is a debug loc and cselib_current_insn is not DEBUG?
2119 If so, we should also avoid converting val to non-DEBUG; probably
2120 easiest setting cselib_current_insn to NULL before the call
2121 above. */
2123 if (dump_file && (dump_flags & TDF_CSELIB))
2125 fputs ("cselib lookup ", dump_file);
2126 print_inline_rtx (dump_file, x, 2);
2127 fprintf (dump_file, " => %u:%u\n",
2128 ret ? ret->uid : 0,
2129 ret ? ret->hash : 0);
2132 return ret;
2135 /* Invalidate any entries in reg_values that overlap REGNO. This is called
2136 if REGNO is changing. MODE is the mode of the assignment to REGNO, which
2137 is used to determine how many hard registers are being changed. If MODE
2138 is VOIDmode, then only REGNO is being changed; this is used when
2139 invalidating call clobbered registers across a call. */
2141 static void
2142 cselib_invalidate_regno (unsigned int regno, machine_mode mode)
2144 unsigned int endregno;
2145 unsigned int i;
2147 /* If we see pseudos after reload, something is _wrong_. */
2148 gcc_assert (!reload_completed || regno < FIRST_PSEUDO_REGISTER
2149 || reg_renumber[regno] < 0);
2151 /* Determine the range of registers that must be invalidated. For
2152 pseudos, only REGNO is affected. For hard regs, we must take MODE
2153 into account, and we must also invalidate lower register numbers
2154 if they contain values that overlap REGNO. */
2155 if (regno < FIRST_PSEUDO_REGISTER)
2157 gcc_assert (mode != VOIDmode);
2159 if (regno < max_value_regs)
2160 i = 0;
2161 else
2162 i = regno - max_value_regs;
2164 endregno = end_hard_regno (mode, regno);
2166 else
2168 i = regno;
2169 endregno = regno + 1;
2172 for (; i < endregno; i++)
2174 struct elt_list **l = &REG_VALUES (i);
2176 /* Go through all known values for this reg; if it overlaps the range
2177 we're invalidating, remove the value. */
2178 while (*l)
2180 cselib_val *v = (*l)->elt;
2181 bool had_locs;
2182 rtx_insn *setting_insn;
2183 struct elt_loc_list **p;
2184 unsigned int this_last = i;
2186 if (i < FIRST_PSEUDO_REGISTER && v != NULL)
2187 this_last = end_hard_regno (GET_MODE (v->val_rtx), i) - 1;
2189 if (this_last < regno || v == NULL
2190 || (v == cfa_base_preserved_val
2191 && i == cfa_base_preserved_regno))
2193 l = &(*l)->next;
2194 continue;
2197 /* We have an overlap. */
2198 if (*l == REG_VALUES (i))
2200 /* Maintain the invariant that the first entry of
2201 REG_VALUES, if present, must be the value used to set
2202 the register, or NULL. This is also nice because
2203 then we won't push the same regno onto user_regs
2204 multiple times. */
2205 (*l)->elt = NULL;
2206 l = &(*l)->next;
2208 else
2209 unchain_one_elt_list (l);
2211 v = canonical_cselib_val (v);
2213 had_locs = v->locs != NULL;
2214 setting_insn = v->locs ? v->locs->setting_insn : NULL;
2216 /* Now, we clear the mapping from value to reg. It must exist, so
2217 this code will crash intentionally if it doesn't. */
2218 for (p = &v->locs; ; p = &(*p)->next)
2220 rtx x = (*p)->loc;
2222 if (REG_P (x) && REGNO (x) == i)
2224 unchain_one_elt_loc_list (p);
2225 break;
2229 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
2231 if (setting_insn && DEBUG_INSN_P (setting_insn))
2232 n_useless_debug_values++;
2233 else
2234 n_useless_values++;
2240 /* Invalidate any locations in the table which are changed because of a
2241 store to MEM_RTX. If this is called because of a non-const call
2242 instruction, MEM_RTX is (mem:BLK const0_rtx). */
2244 static void
2245 cselib_invalidate_mem (rtx mem_rtx)
2247 cselib_val **vp, *v, *next;
2248 int num_mems = 0;
2249 rtx mem_addr;
2251 mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
2252 mem_rtx = canon_rtx (mem_rtx);
2254 vp = &first_containing_mem;
2255 for (v = *vp; v != &dummy_val; v = next)
2257 bool has_mem = false;
2258 struct elt_loc_list **p = &v->locs;
2259 bool had_locs = v->locs != NULL;
2260 rtx_insn *setting_insn = v->locs ? v->locs->setting_insn : NULL;
2262 while (*p)
2264 rtx x = (*p)->loc;
2265 cselib_val *addr;
2266 struct elt_list **mem_chain;
2268 /* MEMs may occur in locations only at the top level; below
2269 that every MEM or REG is substituted by its VALUE. */
2270 if (!MEM_P (x))
2272 p = &(*p)->next;
2273 continue;
2275 if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
2276 && ! canon_anti_dependence (x, false, mem_rtx,
2277 GET_MODE (mem_rtx), mem_addr))
2279 has_mem = true;
2280 num_mems++;
2281 p = &(*p)->next;
2282 continue;
2285 /* This one overlaps. */
2286 /* We must have a mapping from this MEM's address to the
2287 value (E). Remove that, too. */
2288 addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0, GET_MODE (x));
2289 addr = canonical_cselib_val (addr);
2290 gcc_checking_assert (v == canonical_cselib_val (v));
2291 mem_chain = &addr->addr_list;
2292 for (;;)
2294 cselib_val *canon = canonical_cselib_val ((*mem_chain)->elt);
2296 if (canon == v)
2298 unchain_one_elt_list (mem_chain);
2299 break;
2302 /* Record canonicalized elt. */
2303 (*mem_chain)->elt = canon;
2305 mem_chain = &(*mem_chain)->next;
2308 unchain_one_elt_loc_list (p);
2311 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
2313 if (setting_insn && DEBUG_INSN_P (setting_insn))
2314 n_useless_debug_values++;
2315 else
2316 n_useless_values++;
2319 next = v->next_containing_mem;
2320 if (has_mem)
2322 *vp = v;
2323 vp = &(*vp)->next_containing_mem;
2325 else
2326 v->next_containing_mem = NULL;
2328 *vp = &dummy_val;
2331 /* Invalidate DEST, which is being assigned to or clobbered. */
2333 void
2334 cselib_invalidate_rtx (rtx dest)
2336 while (GET_CODE (dest) == SUBREG
2337 || GET_CODE (dest) == ZERO_EXTRACT
2338 || GET_CODE (dest) == STRICT_LOW_PART)
2339 dest = XEXP (dest, 0);
2341 if (REG_P (dest))
2342 cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
2343 else if (MEM_P (dest))
2344 cselib_invalidate_mem (dest);
2347 /* A wrapper for cselib_invalidate_rtx to be called via note_stores. */
2349 static void
2350 cselib_invalidate_rtx_note_stores (rtx dest, const_rtx ignore ATTRIBUTE_UNUSED,
2351 void *data ATTRIBUTE_UNUSED)
2353 cselib_invalidate_rtx (dest);
2356 /* Record the result of a SET instruction. DEST is being set; the source
2357 contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT
2358 describes its address. */
2360 static void
2361 cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
2363 if (src_elt == 0 || side_effects_p (dest))
2364 return;
2366 if (REG_P (dest))
2368 unsigned int dreg = REGNO (dest);
2369 if (dreg < FIRST_PSEUDO_REGISTER)
2371 unsigned int n = REG_NREGS (dest);
2373 if (n > max_value_regs)
2374 max_value_regs = n;
2377 if (REG_VALUES (dreg) == 0)
2379 used_regs[n_used_regs++] = dreg;
2380 REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
2382 else
2384 /* The register should have been invalidated. */
2385 gcc_assert (REG_VALUES (dreg)->elt == 0);
2386 REG_VALUES (dreg)->elt = src_elt;
2389 if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
2390 n_useless_values--;
2391 new_elt_loc_list (src_elt, dest);
2393 else if (MEM_P (dest) && dest_addr_elt != 0
2394 && cselib_record_memory)
2396 if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
2397 n_useless_values--;
2398 add_mem_for_addr (dest_addr_elt, src_elt, dest);
2402 /* Make ELT and X's VALUE equivalent to each other at INSN. */
2404 void
2405 cselib_add_permanent_equiv (cselib_val *elt, rtx x, rtx_insn *insn)
2407 cselib_val *nelt;
2408 rtx_insn *save_cselib_current_insn = cselib_current_insn;
2410 gcc_checking_assert (elt);
2411 gcc_checking_assert (PRESERVED_VALUE_P (elt->val_rtx));
2412 gcc_checking_assert (!side_effects_p (x));
2414 cselib_current_insn = insn;
2416 nelt = cselib_lookup (x, GET_MODE (elt->val_rtx), 1, VOIDmode);
2418 if (nelt != elt)
2420 cselib_any_perm_equivs = true;
2422 if (!PRESERVED_VALUE_P (nelt->val_rtx))
2423 cselib_preserve_value (nelt);
2425 new_elt_loc_list (nelt, elt->val_rtx);
2428 cselib_current_insn = save_cselib_current_insn;
2431 /* Return TRUE if any permanent equivalences have been recorded since
2432 the table was last initialized. */
2433 bool
2434 cselib_have_permanent_equivalences (void)
2436 return cselib_any_perm_equivs;
2439 /* There is no good way to determine how many elements there can be
2440 in a PARALLEL. Since it's fairly cheap, use a really large number. */
2441 #define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
2443 struct cselib_record_autoinc_data
2445 struct cselib_set *sets;
2446 int n_sets;
2449 /* Callback for for_each_inc_dec. Records in ARG the SETs implied by
2450 autoinc RTXs: SRC plus SRCOFF if non-NULL is stored in DEST. */
2452 static int
2453 cselib_record_autoinc_cb (rtx mem ATTRIBUTE_UNUSED, rtx op ATTRIBUTE_UNUSED,
2454 rtx dest, rtx src, rtx srcoff, void *arg)
2456 struct cselib_record_autoinc_data *data;
2457 data = (struct cselib_record_autoinc_data *)arg;
2459 data->sets[data->n_sets].dest = dest;
2461 if (srcoff)
2462 data->sets[data->n_sets].src = gen_rtx_PLUS (GET_MODE (src), src, srcoff);
2463 else
2464 data->sets[data->n_sets].src = src;
2466 data->n_sets++;
2468 return 0;
2471 /* Record the effects of any sets and autoincs in INSN. */
2472 static void
2473 cselib_record_sets (rtx_insn *insn)
2475 int n_sets = 0;
2476 int i;
2477 struct cselib_set sets[MAX_SETS];
2478 rtx body = PATTERN (insn);
2479 rtx cond = 0;
2480 int n_sets_before_autoinc;
2481 struct cselib_record_autoinc_data data;
2483 body = PATTERN (insn);
2484 if (GET_CODE (body) == COND_EXEC)
2486 cond = COND_EXEC_TEST (body);
2487 body = COND_EXEC_CODE (body);
2490 /* Find all sets. */
2491 if (GET_CODE (body) == SET)
2493 sets[0].src = SET_SRC (body);
2494 sets[0].dest = SET_DEST (body);
2495 n_sets = 1;
2497 else if (GET_CODE (body) == PARALLEL)
2499 /* Look through the PARALLEL and record the values being
2500 set, if possible. Also handle any CLOBBERs. */
2501 for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
2503 rtx x = XVECEXP (body, 0, i);
2505 if (GET_CODE (x) == SET)
2507 sets[n_sets].src = SET_SRC (x);
2508 sets[n_sets].dest = SET_DEST (x);
2509 n_sets++;
2514 if (n_sets == 1
2515 && MEM_P (sets[0].src)
2516 && !cselib_record_memory
2517 && MEM_READONLY_P (sets[0].src))
2519 rtx note = find_reg_equal_equiv_note (insn);
2521 if (note && CONSTANT_P (XEXP (note, 0)))
2522 sets[0].src = XEXP (note, 0);
2525 data.sets = sets;
2526 data.n_sets = n_sets_before_autoinc = n_sets;
2527 for_each_inc_dec (PATTERN (insn), cselib_record_autoinc_cb, &data);
2528 n_sets = data.n_sets;
2530 /* Look up the values that are read. Do this before invalidating the
2531 locations that are written. */
2532 for (i = 0; i < n_sets; i++)
2534 rtx dest = sets[i].dest;
2536 /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
2537 the low part after invalidating any knowledge about larger modes. */
2538 if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
2539 sets[i].dest = dest = XEXP (dest, 0);
2541 /* We don't know how to record anything but REG or MEM. */
2542 if (REG_P (dest)
2543 || (MEM_P (dest) && cselib_record_memory))
2545 rtx src = sets[i].src;
2546 if (cond)
2547 src = gen_rtx_IF_THEN_ELSE (GET_MODE (dest), cond, src, dest);
2548 sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1, VOIDmode);
2549 if (MEM_P (dest))
2551 machine_mode address_mode = get_address_mode (dest);
2553 sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0),
2554 address_mode, 1,
2555 GET_MODE (dest));
2557 else
2558 sets[i].dest_addr_elt = 0;
2562 if (cselib_record_sets_hook)
2563 cselib_record_sets_hook (insn, sets, n_sets);
2565 /* Invalidate all locations written by this insn. Note that the elts we
2566 looked up in the previous loop aren't affected, just some of their
2567 locations may go away. */
2568 note_stores (body, cselib_invalidate_rtx_note_stores, NULL);
2570 for (i = n_sets_before_autoinc; i < n_sets; i++)
2571 cselib_invalidate_rtx (sets[i].dest);
2573 /* If this is an asm, look for duplicate sets. This can happen when the
2574 user uses the same value as an output multiple times. This is valid
2575 if the outputs are not actually used thereafter. Treat this case as
2576 if the value isn't actually set. We do this by smashing the destination
2577 to pc_rtx, so that we won't record the value later. */
2578 if (n_sets >= 2 && asm_noperands (body) >= 0)
2580 for (i = 0; i < n_sets; i++)
2582 rtx dest = sets[i].dest;
2583 if (REG_P (dest) || MEM_P (dest))
2585 int j;
2586 for (j = i + 1; j < n_sets; j++)
2587 if (rtx_equal_p (dest, sets[j].dest))
2589 sets[i].dest = pc_rtx;
2590 sets[j].dest = pc_rtx;
2596 /* Now enter the equivalences in our tables. */
2597 for (i = 0; i < n_sets; i++)
2599 rtx dest = sets[i].dest;
2600 if (REG_P (dest)
2601 || (MEM_P (dest) && cselib_record_memory))
2602 cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
2606 /* Return true if INSN in the prologue initializes hard_frame_pointer_rtx. */
2608 bool
2609 fp_setter_insn (rtx_insn *insn)
2611 rtx expr, pat = NULL_RTX;
2613 if (!RTX_FRAME_RELATED_P (insn))
2614 return false;
2616 expr = find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX);
2617 if (expr)
2618 pat = XEXP (expr, 0);
2619 if (!modified_in_p (hard_frame_pointer_rtx, pat ? pat : insn))
2620 return false;
2622 /* Don't return true for frame pointer restores in the epilogue. */
2623 if (find_reg_note (insn, REG_CFA_RESTORE, hard_frame_pointer_rtx))
2624 return false;
2625 return true;
2628 /* Record the effects of INSN. */
2630 void
2631 cselib_process_insn (rtx_insn *insn)
2633 int i;
2634 rtx x;
2636 cselib_current_insn = insn;
2638 /* Forget everything at a CODE_LABEL or a setjmp. */
2639 if ((LABEL_P (insn)
2640 || (CALL_P (insn)
2641 && find_reg_note (insn, REG_SETJMP, NULL)))
2642 && !cselib_preserve_constants)
2644 cselib_reset_table (next_uid);
2645 cselib_current_insn = NULL;
2646 return;
2649 if (! INSN_P (insn))
2651 cselib_current_insn = NULL;
2652 return;
2655 /* If this is a call instruction, forget anything stored in a
2656 call clobbered register, or, if this is not a const call, in
2657 memory. */
2658 if (CALL_P (insn))
2660 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2661 if (call_used_regs[i]
2662 || (REG_VALUES (i) && REG_VALUES (i)->elt
2663 && HARD_REGNO_CALL_PART_CLOBBERED (i,
2664 GET_MODE (REG_VALUES (i)->elt->val_rtx))))
2665 cselib_invalidate_regno (i, reg_raw_mode[i]);
2667 /* Since it is not clear how cselib is going to be used, be
2668 conservative here and treat looping pure or const functions
2669 as if they were regular functions. */
2670 if (RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
2671 || !(RTL_CONST_OR_PURE_CALL_P (insn)))
2672 cselib_invalidate_mem (callmem);
2673 else
2674 /* For const/pure calls, invalidate any argument slots because
2675 they are owned by the callee. */
2676 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
2677 if (GET_CODE (XEXP (x, 0)) == USE
2678 && MEM_P (XEXP (XEXP (x, 0), 0)))
2679 cselib_invalidate_mem (XEXP (XEXP (x, 0), 0));
2682 cselib_record_sets (insn);
2684 /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
2685 after we have processed the insn. */
2686 if (CALL_P (insn))
2688 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
2689 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
2690 cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0));
2691 /* Flush evertything on setjmp. */
2692 if (cselib_preserve_constants
2693 && find_reg_note (insn, REG_SETJMP, NULL))
2695 cselib_preserve_only_values ();
2696 cselib_reset_table (next_uid);
2700 /* On setter of the hard frame pointer if frame_pointer_needed,
2701 invalidate stack_pointer_rtx, so that sp and {,h}fp based
2702 VALUEs are distinct. */
2703 if (reload_completed
2704 && frame_pointer_needed
2705 && fp_setter_insn (insn))
2706 cselib_invalidate_rtx (stack_pointer_rtx);
2708 cselib_current_insn = NULL;
2710 if (n_useless_values > MAX_USELESS_VALUES
2711 /* remove_useless_values is linear in the hash table size. Avoid
2712 quadratic behavior for very large hashtables with very few
2713 useless elements. */
2714 && ((unsigned int)n_useless_values
2715 > (cselib_hash_table->elements () - n_debug_values) / 4))
2716 remove_useless_values ();
2719 /* Initialize cselib for one pass. The caller must also call
2720 init_alias_analysis. */
2722 void
2723 cselib_init (int record_what)
2725 cselib_record_memory = record_what & CSELIB_RECORD_MEMORY;
2726 cselib_preserve_constants = record_what & CSELIB_PRESERVE_CONSTANTS;
2727 cselib_any_perm_equivs = false;
2729 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything,
2730 see canon_true_dependence. This is only created once. */
2731 if (! callmem)
2732 callmem = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode));
2734 cselib_nregs = max_reg_num ();
2736 /* We preserve reg_values to allow expensive clearing of the whole thing.
2737 Reallocate it however if it happens to be too large. */
2738 if (!reg_values || reg_values_size < cselib_nregs
2739 || (reg_values_size > 10 && reg_values_size > cselib_nregs * 4))
2741 free (reg_values);
2742 /* Some space for newly emit instructions so we don't end up
2743 reallocating in between passes. */
2744 reg_values_size = cselib_nregs + (63 + cselib_nregs) / 16;
2745 reg_values = XCNEWVEC (struct elt_list *, reg_values_size);
2747 used_regs = XNEWVEC (unsigned int, cselib_nregs);
2748 n_used_regs = 0;
2749 cselib_hash_table = new hash_table<cselib_hasher> (31);
2750 if (cselib_preserve_constants)
2751 cselib_preserved_hash_table = new hash_table<cselib_hasher> (31);
2752 next_uid = 1;
2755 /* Called when the current user is done with cselib. */
2757 void
2758 cselib_finish (void)
2760 bool preserved = cselib_preserve_constants;
2761 cselib_discard_hook = NULL;
2762 cselib_preserve_constants = false;
2763 cselib_any_perm_equivs = false;
2764 cfa_base_preserved_val = NULL;
2765 cfa_base_preserved_regno = INVALID_REGNUM;
2766 elt_list_pool.release ();
2767 elt_loc_list_pool.release ();
2768 cselib_val_pool.release ();
2769 value_pool.release ();
2770 cselib_clear_table ();
2771 delete cselib_hash_table;
2772 cselib_hash_table = NULL;
2773 if (preserved)
2774 delete cselib_preserved_hash_table;
2775 cselib_preserved_hash_table = NULL;
2776 free (used_regs);
2777 used_regs = 0;
2778 n_useless_values = 0;
2779 n_useless_debug_values = 0;
2780 n_debug_values = 0;
2781 next_uid = 0;
2784 /* Dump the cselib_val *X to FILE *OUT. */
2787 dump_cselib_val (cselib_val **x, FILE *out)
2789 cselib_val *v = *x;
2790 bool need_lf = true;
2792 print_inline_rtx (out, v->val_rtx, 0);
2794 if (v->locs)
2796 struct elt_loc_list *l = v->locs;
2797 if (need_lf)
2799 fputc ('\n', out);
2800 need_lf = false;
2802 fputs (" locs:", out);
2805 if (l->setting_insn)
2806 fprintf (out, "\n from insn %i ",
2807 INSN_UID (l->setting_insn));
2808 else
2809 fprintf (out, "\n ");
2810 print_inline_rtx (out, l->loc, 4);
2812 while ((l = l->next));
2813 fputc ('\n', out);
2815 else
2817 fputs (" no locs", out);
2818 need_lf = true;
2821 if (v->addr_list)
2823 struct elt_list *e = v->addr_list;
2824 if (need_lf)
2826 fputc ('\n', out);
2827 need_lf = false;
2829 fputs (" addr list:", out);
2832 fputs ("\n ", out);
2833 print_inline_rtx (out, e->elt->val_rtx, 2);
2835 while ((e = e->next));
2836 fputc ('\n', out);
2838 else
2840 fputs (" no addrs", out);
2841 need_lf = true;
2844 if (v->next_containing_mem == &dummy_val)
2845 fputs (" last mem\n", out);
2846 else if (v->next_containing_mem)
2848 fputs (" next mem ", out);
2849 print_inline_rtx (out, v->next_containing_mem->val_rtx, 2);
2850 fputc ('\n', out);
2852 else if (need_lf)
2853 fputc ('\n', out);
2855 return 1;
2858 /* Dump to OUT everything in the CSELIB table. */
2860 void
2861 dump_cselib_table (FILE *out)
2863 fprintf (out, "cselib hash table:\n");
2864 cselib_hash_table->traverse <FILE *, dump_cselib_val> (out);
2865 fprintf (out, "cselib preserved hash table:\n");
2866 cselib_preserved_hash_table->traverse <FILE *, dump_cselib_val> (out);
2867 if (first_containing_mem != &dummy_val)
2869 fputs ("first mem ", out);
2870 print_inline_rtx (out, first_containing_mem->val_rtx, 2);
2871 fputc ('\n', out);
2873 fprintf (out, "next uid %i\n", next_uid);
2876 #include "gt-cselib.h"