pa.c (pa_som_asm_init_sections): Fix comment.
[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,
534 GET_MODE (cfa_base_preserved_val->locs->loc));
536 else
538 for (i = 0; i < n_used_regs; i++)
539 REG_VALUES (used_regs[i]) = 0;
540 n_used_regs = 0;
543 if (cselib_preserve_constants)
544 cselib_hash_table->traverse <void *, preserve_constants_and_equivs>
545 (NULL);
546 else
548 cselib_hash_table->empty ();
549 gcc_checking_assert (!cselib_any_perm_equivs);
552 n_useless_values = 0;
553 n_useless_debug_values = 0;
554 n_debug_values = 0;
556 next_uid = num;
558 first_containing_mem = &dummy_val;
561 /* Return the number of the next value that will be generated. */
563 unsigned int
564 cselib_get_next_uid (void)
566 return next_uid;
569 /* Search for X, whose hashcode is HASH, in CSELIB_HASH_TABLE,
570 INSERTing if requested. When X is part of the address of a MEM,
571 MEMMODE should specify the mode of the MEM. */
573 static cselib_val **
574 cselib_find_slot (machine_mode mode, rtx x, hashval_t hash,
575 enum insert_option insert, machine_mode memmode)
577 cselib_val **slot = NULL;
578 cselib_hasher::key lookup = { mode, x, memmode };
579 if (cselib_preserve_constants)
580 slot = cselib_preserved_hash_table->find_slot_with_hash (&lookup, hash,
581 NO_INSERT);
582 if (!slot)
583 slot = cselib_hash_table->find_slot_with_hash (&lookup, hash, insert);
584 return slot;
587 /* Return true if X contains a VALUE rtx. If ONLY_USELESS is set, we
588 only return true for values which point to a cselib_val whose value
589 element has been set to zero, which implies the cselib_val will be
590 removed. */
593 references_value_p (const_rtx x, int only_useless)
595 const enum rtx_code code = GET_CODE (x);
596 const char *fmt = GET_RTX_FORMAT (code);
597 int i, j;
599 if (GET_CODE (x) == VALUE
600 && (! only_useless ||
601 (CSELIB_VAL_PTR (x)->locs == 0 && !PRESERVED_VALUE_P (x))))
602 return 1;
604 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
606 if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless))
607 return 1;
608 else if (fmt[i] == 'E')
609 for (j = 0; j < XVECLEN (x, i); j++)
610 if (references_value_p (XVECEXP (x, i, j), only_useless))
611 return 1;
614 return 0;
617 /* For all locations found in X, delete locations that reference useless
618 values (i.e. values without any location). Called through
619 htab_traverse. */
622 discard_useless_locs (cselib_val **x, void *info ATTRIBUTE_UNUSED)
624 cselib_val *v = *x;
625 struct elt_loc_list **p = &v->locs;
626 bool had_locs = v->locs != NULL;
627 rtx_insn *setting_insn = v->locs ? v->locs->setting_insn : NULL;
629 while (*p)
631 if (references_value_p ((*p)->loc, 1))
632 unchain_one_elt_loc_list (p);
633 else
634 p = &(*p)->next;
637 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
639 if (setting_insn && DEBUG_INSN_P (setting_insn))
640 n_useless_debug_values++;
641 else
642 n_useless_values++;
643 values_became_useless = 1;
645 return 1;
648 /* If X is a value with no locations, remove it from the hashtable. */
651 discard_useless_values (cselib_val **x, void *info ATTRIBUTE_UNUSED)
653 cselib_val *v = *x;
655 if (v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
657 if (cselib_discard_hook)
658 cselib_discard_hook (v);
660 CSELIB_VAL_PTR (v->val_rtx) = NULL;
661 cselib_hash_table->clear_slot (x);
662 unchain_one_value (v);
663 n_useless_values--;
666 return 1;
669 /* Clean out useless values (i.e. those which no longer have locations
670 associated with them) from the hash table. */
672 static void
673 remove_useless_values (void)
675 cselib_val **p, *v;
677 /* First pass: eliminate locations that reference the value. That in
678 turn can make more values useless. */
681 values_became_useless = 0;
682 cselib_hash_table->traverse <void *, discard_useless_locs> (NULL);
684 while (values_became_useless);
686 /* Second pass: actually remove the values. */
688 p = &first_containing_mem;
689 for (v = *p; v != &dummy_val; v = v->next_containing_mem)
690 if (v->locs && v == canonical_cselib_val (v))
692 *p = v;
693 p = &(*p)->next_containing_mem;
695 *p = &dummy_val;
697 n_useless_values += n_useless_debug_values;
698 n_debug_values -= n_useless_debug_values;
699 n_useless_debug_values = 0;
701 cselib_hash_table->traverse <void *, discard_useless_values> (NULL);
703 gcc_assert (!n_useless_values);
706 /* Arrange for a value to not be removed from the hash table even if
707 it becomes useless. */
709 void
710 cselib_preserve_value (cselib_val *v)
712 PRESERVED_VALUE_P (v->val_rtx) = 1;
715 /* Test whether a value is preserved. */
717 bool
718 cselib_preserved_value_p (cselib_val *v)
720 return PRESERVED_VALUE_P (v->val_rtx);
723 /* Arrange for a REG value to be assumed constant through the whole function,
724 never invalidated and preserved across cselib_reset_table calls. */
726 void
727 cselib_preserve_cfa_base_value (cselib_val *v, unsigned int regno)
729 if (cselib_preserve_constants
730 && v->locs
731 && REG_P (v->locs->loc))
733 cfa_base_preserved_val = v;
734 cfa_base_preserved_regno = regno;
738 /* Clean all non-constant expressions in the hash table, but retain
739 their values. */
741 void
742 cselib_preserve_only_values (void)
744 int i;
746 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
747 cselib_invalidate_regno (i, reg_raw_mode[i]);
749 cselib_invalidate_mem (callmem);
751 remove_useless_values ();
753 gcc_assert (first_containing_mem == &dummy_val);
756 /* Arrange for a value to be marked as based on stack pointer
757 for find_base_term purposes. */
759 void
760 cselib_set_value_sp_based (cselib_val *v)
762 SP_BASED_VALUE_P (v->val_rtx) = 1;
765 /* Test whether a value is based on stack pointer for
766 find_base_term purposes. */
768 bool
769 cselib_sp_based_value_p (cselib_val *v)
771 return SP_BASED_VALUE_P (v->val_rtx);
774 /* Return the mode in which a register was last set. If X is not a
775 register, return its mode. If the mode in which the register was
776 set is not known, or the value was already clobbered, return
777 VOIDmode. */
779 machine_mode
780 cselib_reg_set_mode (const_rtx x)
782 if (!REG_P (x))
783 return GET_MODE (x);
785 if (REG_VALUES (REGNO (x)) == NULL
786 || REG_VALUES (REGNO (x))->elt == NULL)
787 return VOIDmode;
789 return GET_MODE (REG_VALUES (REGNO (x))->elt->val_rtx);
792 /* If x is a PLUS or an autoinc operation, expand the operation,
793 storing the offset, if any, in *OFF. */
795 static rtx
796 autoinc_split (rtx x, rtx *off, machine_mode memmode)
798 switch (GET_CODE (x))
800 case PLUS:
801 *off = XEXP (x, 1);
802 return XEXP (x, 0);
804 case PRE_DEC:
805 if (memmode == VOIDmode)
806 return x;
808 *off = GEN_INT (-GET_MODE_SIZE (memmode));
809 return XEXP (x, 0);
811 case PRE_INC:
812 if (memmode == VOIDmode)
813 return x;
815 *off = GEN_INT (GET_MODE_SIZE (memmode));
816 return XEXP (x, 0);
818 case PRE_MODIFY:
819 return XEXP (x, 1);
821 case POST_DEC:
822 case POST_INC:
823 case POST_MODIFY:
824 return XEXP (x, 0);
826 default:
827 return x;
831 /* Return nonzero if we can prove that X and Y contain the same value,
832 taking our gathered information into account. MEMMODE holds the
833 mode of the enclosing MEM, if any, as required to deal with autoinc
834 addressing modes. If X and Y are not (known to be) part of
835 addresses, MEMMODE should be VOIDmode. */
838 rtx_equal_for_cselib_1 (rtx x, rtx y, machine_mode memmode, int depth)
840 enum rtx_code code;
841 const char *fmt;
842 int i;
844 if (REG_P (x) || MEM_P (x))
846 cselib_val *e = cselib_lookup (x, GET_MODE (x), 0, memmode);
848 if (e)
849 x = e->val_rtx;
852 if (REG_P (y) || MEM_P (y))
854 cselib_val *e = cselib_lookup (y, GET_MODE (y), 0, memmode);
856 if (e)
857 y = e->val_rtx;
860 if (x == y)
861 return 1;
863 if (GET_CODE (x) == VALUE)
865 cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (x));
866 struct elt_loc_list *l;
868 if (GET_CODE (y) == VALUE)
869 return e == canonical_cselib_val (CSELIB_VAL_PTR (y));
871 if (depth == 128)
872 return 0;
874 for (l = e->locs; l; l = l->next)
876 rtx t = l->loc;
878 /* Avoid infinite recursion. We know we have the canonical
879 value, so we can just skip any values in the equivalence
880 list. */
881 if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
882 continue;
883 else if (rtx_equal_for_cselib_1 (t, y, memmode, depth + 1))
884 return 1;
887 return 0;
889 else if (GET_CODE (y) == VALUE)
891 cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (y));
892 struct elt_loc_list *l;
894 if (depth == 128)
895 return 0;
897 for (l = e->locs; l; l = l->next)
899 rtx t = l->loc;
901 if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
902 continue;
903 else if (rtx_equal_for_cselib_1 (x, t, memmode, depth + 1))
904 return 1;
907 return 0;
910 if (GET_MODE (x) != GET_MODE (y))
911 return 0;
913 if (GET_CODE (x) != GET_CODE (y))
915 rtx xorig = x, yorig = y;
916 rtx xoff = NULL, yoff = NULL;
918 x = autoinc_split (x, &xoff, memmode);
919 y = autoinc_split (y, &yoff, memmode);
921 if (!xoff != !yoff)
922 return 0;
924 if (xoff && !rtx_equal_for_cselib_1 (xoff, yoff, memmode, depth))
925 return 0;
927 /* Don't recurse if nothing changed. */
928 if (x != xorig || y != yorig)
929 return rtx_equal_for_cselib_1 (x, y, memmode, depth);
931 return 0;
934 /* These won't be handled correctly by the code below. */
935 switch (GET_CODE (x))
937 CASE_CONST_UNIQUE:
938 case DEBUG_EXPR:
939 return 0;
941 case DEBUG_IMPLICIT_PTR:
942 return DEBUG_IMPLICIT_PTR_DECL (x)
943 == DEBUG_IMPLICIT_PTR_DECL (y);
945 case DEBUG_PARAMETER_REF:
946 return DEBUG_PARAMETER_REF_DECL (x)
947 == DEBUG_PARAMETER_REF_DECL (y);
949 case ENTRY_VALUE:
950 /* ENTRY_VALUEs are function invariant, it is thus undesirable to
951 use rtx_equal_for_cselib_1 to compare the operands. */
952 return rtx_equal_p (ENTRY_VALUE_EXP (x), ENTRY_VALUE_EXP (y));
954 case LABEL_REF:
955 return label_ref_label (x) == label_ref_label (y);
957 case REG:
958 return REGNO (x) == REGNO (y);
960 case MEM:
961 /* We have to compare any autoinc operations in the addresses
962 using this MEM's mode. */
963 return rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 0), GET_MODE (x),
964 depth);
966 default:
967 break;
970 code = GET_CODE (x);
971 fmt = GET_RTX_FORMAT (code);
973 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
975 int j;
977 switch (fmt[i])
979 case 'w':
980 if (XWINT (x, i) != XWINT (y, i))
981 return 0;
982 break;
984 case 'n':
985 case 'i':
986 if (XINT (x, i) != XINT (y, i))
987 return 0;
988 break;
990 case 'V':
991 case 'E':
992 /* Two vectors must have the same length. */
993 if (XVECLEN (x, i) != XVECLEN (y, i))
994 return 0;
996 /* And the corresponding elements must match. */
997 for (j = 0; j < XVECLEN (x, i); j++)
998 if (! rtx_equal_for_cselib_1 (XVECEXP (x, i, j),
999 XVECEXP (y, i, j), memmode, depth))
1000 return 0;
1001 break;
1003 case 'e':
1004 if (i == 1
1005 && targetm.commutative_p (x, UNKNOWN)
1006 && rtx_equal_for_cselib_1 (XEXP (x, 1), XEXP (y, 0), memmode,
1007 depth)
1008 && rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 1), memmode,
1009 depth))
1010 return 1;
1011 if (! rtx_equal_for_cselib_1 (XEXP (x, i), XEXP (y, i), memmode,
1012 depth))
1013 return 0;
1014 break;
1016 case 'S':
1017 case 's':
1018 if (strcmp (XSTR (x, i), XSTR (y, i)))
1019 return 0;
1020 break;
1022 case 'u':
1023 /* These are just backpointers, so they don't matter. */
1024 break;
1026 case '0':
1027 case 't':
1028 break;
1030 /* It is believed that rtx's at this level will never
1031 contain anything but integers and other rtx's,
1032 except for within LABEL_REFs and SYMBOL_REFs. */
1033 default:
1034 gcc_unreachable ();
1037 return 1;
1040 /* Hash an rtx. Return 0 if we couldn't hash the rtx.
1041 For registers and memory locations, we look up their cselib_val structure
1042 and return its VALUE element.
1043 Possible reasons for return 0 are: the object is volatile, or we couldn't
1044 find a register or memory location in the table and CREATE is zero. If
1045 CREATE is nonzero, table elts are created for regs and mem.
1046 N.B. this hash function returns the same hash value for RTXes that
1047 differ only in the order of operands, thus it is suitable for comparisons
1048 that take commutativity into account.
1049 If we wanted to also support associative rules, we'd have to use a different
1050 strategy to avoid returning spurious 0, e.g. return ~(~0U >> 1) .
1051 MEMMODE indicates the mode of an enclosing MEM, and it's only
1052 used to compute autoinc values.
1053 We used to have a MODE argument for hashing for CONST_INTs, but that
1054 didn't make sense, since it caused spurious hash differences between
1055 (set (reg:SI 1) (const_int))
1056 (plus:SI (reg:SI 2) (reg:SI 1))
1058 (plus:SI (reg:SI 2) (const_int))
1059 If the mode is important in any context, it must be checked specifically
1060 in a comparison anyway, since relying on hash differences is unsafe. */
1062 static unsigned int
1063 cselib_hash_rtx (rtx x, int create, machine_mode memmode)
1065 cselib_val *e;
1066 int i, j;
1067 enum rtx_code code;
1068 const char *fmt;
1069 unsigned int hash = 0;
1071 code = GET_CODE (x);
1072 hash += (unsigned) code + (unsigned) GET_MODE (x);
1074 switch (code)
1076 case VALUE:
1077 e = CSELIB_VAL_PTR (x);
1078 return e->hash;
1080 case MEM:
1081 case REG:
1082 e = cselib_lookup (x, GET_MODE (x), create, memmode);
1083 if (! e)
1084 return 0;
1086 return e->hash;
1088 case DEBUG_EXPR:
1089 hash += ((unsigned) DEBUG_EXPR << 7)
1090 + DEBUG_TEMP_UID (DEBUG_EXPR_TREE_DECL (x));
1091 return hash ? hash : (unsigned int) DEBUG_EXPR;
1093 case DEBUG_IMPLICIT_PTR:
1094 hash += ((unsigned) DEBUG_IMPLICIT_PTR << 7)
1095 + DECL_UID (DEBUG_IMPLICIT_PTR_DECL (x));
1096 return hash ? hash : (unsigned int) DEBUG_IMPLICIT_PTR;
1098 case DEBUG_PARAMETER_REF:
1099 hash += ((unsigned) DEBUG_PARAMETER_REF << 7)
1100 + DECL_UID (DEBUG_PARAMETER_REF_DECL (x));
1101 return hash ? hash : (unsigned int) DEBUG_PARAMETER_REF;
1103 case ENTRY_VALUE:
1104 /* ENTRY_VALUEs are function invariant, thus try to avoid
1105 recursing on argument if ENTRY_VALUE is one of the
1106 forms emitted by expand_debug_expr, otherwise
1107 ENTRY_VALUE hash would depend on the current value
1108 in some register or memory. */
1109 if (REG_P (ENTRY_VALUE_EXP (x)))
1110 hash += (unsigned int) REG
1111 + (unsigned int) GET_MODE (ENTRY_VALUE_EXP (x))
1112 + (unsigned int) REGNO (ENTRY_VALUE_EXP (x));
1113 else if (MEM_P (ENTRY_VALUE_EXP (x))
1114 && REG_P (XEXP (ENTRY_VALUE_EXP (x), 0)))
1115 hash += (unsigned int) MEM
1116 + (unsigned int) GET_MODE (XEXP (ENTRY_VALUE_EXP (x), 0))
1117 + (unsigned int) REGNO (XEXP (ENTRY_VALUE_EXP (x), 0));
1118 else
1119 hash += cselib_hash_rtx (ENTRY_VALUE_EXP (x), create, memmode);
1120 return hash ? hash : (unsigned int) ENTRY_VALUE;
1122 case CONST_INT:
1123 hash += ((unsigned) CONST_INT << 7) + UINTVAL (x);
1124 return hash ? hash : (unsigned int) CONST_INT;
1126 case CONST_WIDE_INT:
1127 for (i = 0; i < CONST_WIDE_INT_NUNITS (x); i++)
1128 hash += CONST_WIDE_INT_ELT (x, i);
1129 return hash;
1131 case CONST_DOUBLE:
1132 /* This is like the general case, except that it only counts
1133 the integers representing the constant. */
1134 hash += (unsigned) code + (unsigned) GET_MODE (x);
1135 if (TARGET_SUPPORTS_WIDE_INT == 0 && GET_MODE (x) == VOIDmode)
1136 hash += ((unsigned) CONST_DOUBLE_LOW (x)
1137 + (unsigned) CONST_DOUBLE_HIGH (x));
1138 else
1139 hash += real_hash (CONST_DOUBLE_REAL_VALUE (x));
1140 return hash ? hash : (unsigned int) CONST_DOUBLE;
1142 case CONST_FIXED:
1143 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1144 hash += fixed_hash (CONST_FIXED_VALUE (x));
1145 return hash ? hash : (unsigned int) CONST_FIXED;
1147 case CONST_VECTOR:
1149 int units;
1150 rtx elt;
1152 units = CONST_VECTOR_NUNITS (x);
1154 for (i = 0; i < units; ++i)
1156 elt = CONST_VECTOR_ELT (x, i);
1157 hash += cselib_hash_rtx (elt, 0, memmode);
1160 return hash;
1163 /* Assume there is only one rtx object for any given label. */
1164 case LABEL_REF:
1165 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1166 differences and differences between each stage's debugging dumps. */
1167 hash += (((unsigned int) LABEL_REF << 7)
1168 + CODE_LABEL_NUMBER (label_ref_label (x)));
1169 return hash ? hash : (unsigned int) LABEL_REF;
1171 case SYMBOL_REF:
1173 /* Don't hash on the symbol's address to avoid bootstrap differences.
1174 Different hash values may cause expressions to be recorded in
1175 different orders and thus different registers to be used in the
1176 final assembler. This also avoids differences in the dump files
1177 between various stages. */
1178 unsigned int h = 0;
1179 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1181 while (*p)
1182 h += (h << 7) + *p++; /* ??? revisit */
1184 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1185 return hash ? hash : (unsigned int) SYMBOL_REF;
1188 case PRE_DEC:
1189 case PRE_INC:
1190 /* We can't compute these without knowing the MEM mode. */
1191 gcc_assert (memmode != VOIDmode);
1192 i = GET_MODE_SIZE (memmode);
1193 if (code == PRE_DEC)
1194 i = -i;
1195 /* Adjust the hash so that (mem:MEMMODE (pre_* (reg))) hashes
1196 like (mem:MEMMODE (plus (reg) (const_int I))). */
1197 hash += (unsigned) PLUS - (unsigned)code
1198 + cselib_hash_rtx (XEXP (x, 0), create, memmode)
1199 + cselib_hash_rtx (GEN_INT (i), create, memmode);
1200 return hash ? hash : 1 + (unsigned) PLUS;
1202 case PRE_MODIFY:
1203 gcc_assert (memmode != VOIDmode);
1204 return cselib_hash_rtx (XEXP (x, 1), create, memmode);
1206 case POST_DEC:
1207 case POST_INC:
1208 case POST_MODIFY:
1209 gcc_assert (memmode != VOIDmode);
1210 return cselib_hash_rtx (XEXP (x, 0), create, memmode);
1212 case PC:
1213 case CC0:
1214 case CALL:
1215 case UNSPEC_VOLATILE:
1216 return 0;
1218 case ASM_OPERANDS:
1219 if (MEM_VOLATILE_P (x))
1220 return 0;
1222 break;
1224 default:
1225 break;
1228 i = GET_RTX_LENGTH (code) - 1;
1229 fmt = GET_RTX_FORMAT (code);
1230 for (; i >= 0; i--)
1232 switch (fmt[i])
1234 case 'e':
1236 rtx tem = XEXP (x, i);
1237 unsigned int tem_hash = cselib_hash_rtx (tem, create, memmode);
1239 if (tem_hash == 0)
1240 return 0;
1242 hash += tem_hash;
1244 break;
1245 case 'E':
1246 for (j = 0; j < XVECLEN (x, i); j++)
1248 unsigned int tem_hash
1249 = cselib_hash_rtx (XVECEXP (x, i, j), create, memmode);
1251 if (tem_hash == 0)
1252 return 0;
1254 hash += tem_hash;
1256 break;
1258 case 's':
1260 const unsigned char *p = (const unsigned char *) XSTR (x, i);
1262 if (p)
1263 while (*p)
1264 hash += *p++;
1265 break;
1268 case 'i':
1269 hash += XINT (x, i);
1270 break;
1272 case '0':
1273 case 't':
1274 /* unused */
1275 break;
1277 default:
1278 gcc_unreachable ();
1282 return hash ? hash : 1 + (unsigned int) GET_CODE (x);
1285 /* Create a new value structure for VALUE and initialize it. The mode of the
1286 value is MODE. */
1288 static inline cselib_val *
1289 new_cselib_val (unsigned int hash, machine_mode mode, rtx x)
1291 cselib_val *e = cselib_val_pool.allocate ();
1293 gcc_assert (hash);
1294 gcc_assert (next_uid);
1296 e->hash = hash;
1297 e->uid = next_uid++;
1298 /* We use an alloc pool to allocate this RTL construct because it
1299 accounts for about 8% of the overall memory usage. We know
1300 precisely when we can have VALUE RTXen (when cselib is active)
1301 so we don't need to put them in garbage collected memory.
1302 ??? Why should a VALUE be an RTX in the first place? */
1303 e->val_rtx = (rtx_def*) value_pool.allocate ();
1304 memset (e->val_rtx, 0, RTX_HDR_SIZE);
1305 PUT_CODE (e->val_rtx, VALUE);
1306 PUT_MODE (e->val_rtx, mode);
1307 CSELIB_VAL_PTR (e->val_rtx) = e;
1308 e->addr_list = 0;
1309 e->locs = 0;
1310 e->next_containing_mem = 0;
1312 if (dump_file && (dump_flags & TDF_CSELIB))
1314 fprintf (dump_file, "cselib value %u:%u ", e->uid, hash);
1315 if (flag_dump_noaddr || flag_dump_unnumbered)
1316 fputs ("# ", dump_file);
1317 else
1318 fprintf (dump_file, "%p ", (void*)e);
1319 print_rtl_single (dump_file, x);
1320 fputc ('\n', dump_file);
1323 return e;
1326 /* ADDR_ELT is a value that is used as address. MEM_ELT is the value that
1327 contains the data at this address. X is a MEM that represents the
1328 value. Update the two value structures to represent this situation. */
1330 static void
1331 add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x)
1333 addr_elt = canonical_cselib_val (addr_elt);
1334 mem_elt = canonical_cselib_val (mem_elt);
1336 /* Avoid duplicates. */
1337 addr_space_t as = MEM_ADDR_SPACE (x);
1338 for (elt_loc_list *l = mem_elt->locs; l; l = l->next)
1339 if (MEM_P (l->loc)
1340 && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt
1341 && MEM_ADDR_SPACE (l->loc) == as)
1343 promote_debug_loc (l);
1344 return;
1347 addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
1348 new_elt_loc_list (mem_elt,
1349 replace_equiv_address_nv (x, addr_elt->val_rtx));
1350 if (mem_elt->next_containing_mem == NULL)
1352 mem_elt->next_containing_mem = first_containing_mem;
1353 first_containing_mem = mem_elt;
1357 /* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx.
1358 If CREATE, make a new one if we haven't seen it before. */
1360 static cselib_val *
1361 cselib_lookup_mem (rtx x, int create)
1363 machine_mode mode = GET_MODE (x);
1364 machine_mode addr_mode;
1365 cselib_val **slot;
1366 cselib_val *addr;
1367 cselib_val *mem_elt;
1369 if (MEM_VOLATILE_P (x) || mode == BLKmode
1370 || !cselib_record_memory
1371 || (FLOAT_MODE_P (mode) && flag_float_store))
1372 return 0;
1374 addr_mode = GET_MODE (XEXP (x, 0));
1375 if (addr_mode == VOIDmode)
1376 addr_mode = Pmode;
1378 /* Look up the value for the address. */
1379 addr = cselib_lookup (XEXP (x, 0), addr_mode, create, mode);
1380 if (! addr)
1381 return 0;
1382 addr = canonical_cselib_val (addr);
1384 /* Find a value that describes a value of our mode at that address. */
1385 addr_space_t as = MEM_ADDR_SPACE (x);
1386 for (elt_list *l = addr->addr_list; l; l = l->next)
1387 if (GET_MODE (l->elt->val_rtx) == mode)
1389 for (elt_loc_list *l2 = l->elt->locs; l2; l2 = l2->next)
1390 if (MEM_P (l2->loc) && MEM_ADDR_SPACE (l2->loc) == as)
1392 promote_debug_loc (l->elt->locs);
1393 return l->elt;
1397 if (! create)
1398 return 0;
1400 mem_elt = new_cselib_val (next_uid, mode, x);
1401 add_mem_for_addr (addr, mem_elt, x);
1402 slot = cselib_find_slot (mode, x, mem_elt->hash, INSERT, VOIDmode);
1403 *slot = mem_elt;
1404 return mem_elt;
1407 /* Search through the possible substitutions in P. We prefer a non reg
1408 substitution because this allows us to expand the tree further. If
1409 we find, just a reg, take the lowest regno. There may be several
1410 non-reg results, we just take the first one because they will all
1411 expand to the same place. */
1413 static rtx
1414 expand_loc (struct elt_loc_list *p, struct expand_value_data *evd,
1415 int max_depth)
1417 rtx reg_result = NULL;
1418 unsigned int regno = UINT_MAX;
1419 struct elt_loc_list *p_in = p;
1421 for (; p; p = p->next)
1423 /* Return these right away to avoid returning stack pointer based
1424 expressions for frame pointer and vice versa, which is something
1425 that would confuse DSE. See the comment in cselib_expand_value_rtx_1
1426 for more details. */
1427 if (REG_P (p->loc)
1428 && (REGNO (p->loc) == STACK_POINTER_REGNUM
1429 || REGNO (p->loc) == FRAME_POINTER_REGNUM
1430 || REGNO (p->loc) == HARD_FRAME_POINTER_REGNUM
1431 || REGNO (p->loc) == cfa_base_preserved_regno))
1432 return p->loc;
1433 /* Avoid infinite recursion trying to expand a reg into a
1434 the same reg. */
1435 if ((REG_P (p->loc))
1436 && (REGNO (p->loc) < regno)
1437 && !bitmap_bit_p (evd->regs_active, REGNO (p->loc)))
1439 reg_result = p->loc;
1440 regno = REGNO (p->loc);
1442 /* Avoid infinite recursion and do not try to expand the
1443 value. */
1444 else if (GET_CODE (p->loc) == VALUE
1445 && CSELIB_VAL_PTR (p->loc)->locs == p_in)
1446 continue;
1447 else if (!REG_P (p->loc))
1449 rtx result, note;
1450 if (dump_file && (dump_flags & TDF_CSELIB))
1452 print_inline_rtx (dump_file, p->loc, 0);
1453 fprintf (dump_file, "\n");
1455 if (GET_CODE (p->loc) == LO_SUM
1456 && GET_CODE (XEXP (p->loc, 1)) == SYMBOL_REF
1457 && p->setting_insn
1458 && (note = find_reg_note (p->setting_insn, REG_EQUAL, NULL_RTX))
1459 && XEXP (note, 0) == XEXP (p->loc, 1))
1460 return XEXP (p->loc, 1);
1461 result = cselib_expand_value_rtx_1 (p->loc, evd, max_depth - 1);
1462 if (result)
1463 return result;
1468 if (regno != UINT_MAX)
1470 rtx result;
1471 if (dump_file && (dump_flags & TDF_CSELIB))
1472 fprintf (dump_file, "r%d\n", regno);
1474 result = cselib_expand_value_rtx_1 (reg_result, evd, max_depth - 1);
1475 if (result)
1476 return result;
1479 if (dump_file && (dump_flags & TDF_CSELIB))
1481 if (reg_result)
1483 print_inline_rtx (dump_file, reg_result, 0);
1484 fprintf (dump_file, "\n");
1486 else
1487 fprintf (dump_file, "NULL\n");
1489 return reg_result;
1493 /* Forward substitute and expand an expression out to its roots.
1494 This is the opposite of common subexpression. Because local value
1495 numbering is such a weak optimization, the expanded expression is
1496 pretty much unique (not from a pointer equals point of view but
1497 from a tree shape point of view.
1499 This function returns NULL if the expansion fails. The expansion
1500 will fail if there is no value number for one of the operands or if
1501 one of the operands has been overwritten between the current insn
1502 and the beginning of the basic block. For instance x has no
1503 expansion in:
1505 r1 <- r1 + 3
1506 x <- r1 + 8
1508 REGS_ACTIVE is a scratch bitmap that should be clear when passing in.
1509 It is clear on return. */
1512 cselib_expand_value_rtx (rtx orig, bitmap regs_active, int max_depth)
1514 struct expand_value_data evd;
1516 evd.regs_active = regs_active;
1517 evd.callback = NULL;
1518 evd.callback_arg = NULL;
1519 evd.dummy = false;
1521 return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
1524 /* Same as cselib_expand_value_rtx, but using a callback to try to
1525 resolve some expressions. The CB function should return ORIG if it
1526 can't or does not want to deal with a certain RTX. Any other
1527 return value, including NULL, will be used as the expansion for
1528 VALUE, without any further changes. */
1531 cselib_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
1532 cselib_expand_callback cb, void *data)
1534 struct expand_value_data evd;
1536 evd.regs_active = regs_active;
1537 evd.callback = cb;
1538 evd.callback_arg = data;
1539 evd.dummy = false;
1541 return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
1544 /* Similar to cselib_expand_value_rtx_cb, but no rtxs are actually copied
1545 or simplified. Useful to find out whether cselib_expand_value_rtx_cb
1546 would return NULL or non-NULL, without allocating new rtx. */
1548 bool
1549 cselib_dummy_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
1550 cselib_expand_callback cb, void *data)
1552 struct expand_value_data evd;
1554 evd.regs_active = regs_active;
1555 evd.callback = cb;
1556 evd.callback_arg = data;
1557 evd.dummy = true;
1559 return cselib_expand_value_rtx_1 (orig, &evd, max_depth) != NULL;
1562 /* Internal implementation of cselib_expand_value_rtx and
1563 cselib_expand_value_rtx_cb. */
1565 static rtx
1566 cselib_expand_value_rtx_1 (rtx orig, struct expand_value_data *evd,
1567 int max_depth)
1569 rtx copy, scopy;
1570 int i, j;
1571 RTX_CODE code;
1572 const char *format_ptr;
1573 machine_mode mode;
1575 code = GET_CODE (orig);
1577 /* For the context of dse, if we end up expand into a huge tree, we
1578 will not have a useful address, so we might as well just give up
1579 quickly. */
1580 if (max_depth <= 0)
1581 return NULL;
1583 switch (code)
1585 case REG:
1587 struct elt_list *l = REG_VALUES (REGNO (orig));
1589 if (l && l->elt == NULL)
1590 l = l->next;
1591 for (; l; l = l->next)
1592 if (GET_MODE (l->elt->val_rtx) == GET_MODE (orig))
1594 rtx result;
1595 unsigned regno = REGNO (orig);
1597 /* The only thing that we are not willing to do (this
1598 is requirement of dse and if others potential uses
1599 need this function we should add a parm to control
1600 it) is that we will not substitute the
1601 STACK_POINTER_REGNUM, FRAME_POINTER or the
1602 HARD_FRAME_POINTER.
1604 These expansions confuses the code that notices that
1605 stores into the frame go dead at the end of the
1606 function and that the frame is not effected by calls
1607 to subroutines. If you allow the
1608 STACK_POINTER_REGNUM substitution, then dse will
1609 think that parameter pushing also goes dead which is
1610 wrong. If you allow the FRAME_POINTER or the
1611 HARD_FRAME_POINTER then you lose the opportunity to
1612 make the frame assumptions. */
1613 if (regno == STACK_POINTER_REGNUM
1614 || regno == FRAME_POINTER_REGNUM
1615 || regno == HARD_FRAME_POINTER_REGNUM
1616 || regno == cfa_base_preserved_regno)
1617 return orig;
1619 bitmap_set_bit (evd->regs_active, regno);
1621 if (dump_file && (dump_flags & TDF_CSELIB))
1622 fprintf (dump_file, "expanding: r%d into: ", regno);
1624 result = expand_loc (l->elt->locs, evd, max_depth);
1625 bitmap_clear_bit (evd->regs_active, regno);
1627 if (result)
1628 return result;
1629 else
1630 return orig;
1632 return orig;
1635 CASE_CONST_ANY:
1636 case SYMBOL_REF:
1637 case CODE_LABEL:
1638 case PC:
1639 case CC0:
1640 case SCRATCH:
1641 /* SCRATCH must be shared because they represent distinct values. */
1642 return orig;
1643 case CLOBBER:
1644 if (REG_P (XEXP (orig, 0)) && HARD_REGISTER_NUM_P (REGNO (XEXP (orig, 0))))
1645 return orig;
1646 break;
1648 case CONST:
1649 if (shared_const_p (orig))
1650 return orig;
1651 break;
1653 case SUBREG:
1655 rtx subreg;
1657 if (evd->callback)
1659 subreg = evd->callback (orig, evd->regs_active, max_depth,
1660 evd->callback_arg);
1661 if (subreg != orig)
1662 return subreg;
1665 subreg = cselib_expand_value_rtx_1 (SUBREG_REG (orig), evd,
1666 max_depth - 1);
1667 if (!subreg)
1668 return NULL;
1669 scopy = simplify_gen_subreg (GET_MODE (orig), subreg,
1670 GET_MODE (SUBREG_REG (orig)),
1671 SUBREG_BYTE (orig));
1672 if (scopy == NULL
1673 || (GET_CODE (scopy) == SUBREG
1674 && !REG_P (SUBREG_REG (scopy))
1675 && !MEM_P (SUBREG_REG (scopy))))
1676 return NULL;
1678 return scopy;
1681 case VALUE:
1683 rtx result;
1685 if (dump_file && (dump_flags & TDF_CSELIB))
1687 fputs ("\nexpanding ", dump_file);
1688 print_rtl_single (dump_file, orig);
1689 fputs (" into...", dump_file);
1692 if (evd->callback)
1694 result = evd->callback (orig, evd->regs_active, max_depth,
1695 evd->callback_arg);
1697 if (result != orig)
1698 return result;
1701 result = expand_loc (CSELIB_VAL_PTR (orig)->locs, evd, max_depth);
1702 return result;
1705 case DEBUG_EXPR:
1706 if (evd->callback)
1707 return evd->callback (orig, evd->regs_active, max_depth,
1708 evd->callback_arg);
1709 return orig;
1711 default:
1712 break;
1715 /* Copy the various flags, fields, and other information. We assume
1716 that all fields need copying, and then clear the fields that should
1717 not be copied. That is the sensible default behavior, and forces
1718 us to explicitly document why we are *not* copying a flag. */
1719 if (evd->dummy)
1720 copy = NULL;
1721 else
1722 copy = shallow_copy_rtx (orig);
1724 format_ptr = GET_RTX_FORMAT (code);
1726 for (i = 0; i < GET_RTX_LENGTH (code); i++)
1727 switch (*format_ptr++)
1729 case 'e':
1730 if (XEXP (orig, i) != NULL)
1732 rtx result = cselib_expand_value_rtx_1 (XEXP (orig, i), evd,
1733 max_depth - 1);
1734 if (!result)
1735 return NULL;
1736 if (copy)
1737 XEXP (copy, i) = result;
1739 break;
1741 case 'E':
1742 case 'V':
1743 if (XVEC (orig, i) != NULL)
1745 if (copy)
1746 XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i));
1747 for (j = 0; j < XVECLEN (orig, i); j++)
1749 rtx result = cselib_expand_value_rtx_1 (XVECEXP (orig, i, j),
1750 evd, max_depth - 1);
1751 if (!result)
1752 return NULL;
1753 if (copy)
1754 XVECEXP (copy, i, j) = result;
1757 break;
1759 case 't':
1760 case 'w':
1761 case 'i':
1762 case 's':
1763 case 'S':
1764 case 'T':
1765 case 'u':
1766 case 'B':
1767 case '0':
1768 /* These are left unchanged. */
1769 break;
1771 default:
1772 gcc_unreachable ();
1775 if (evd->dummy)
1776 return orig;
1778 mode = GET_MODE (copy);
1779 /* If an operand has been simplified into CONST_INT, which doesn't
1780 have a mode and the mode isn't derivable from whole rtx's mode,
1781 try simplify_*_operation first with mode from original's operand
1782 and as a fallback wrap CONST_INT into gen_rtx_CONST. */
1783 scopy = copy;
1784 switch (GET_RTX_CLASS (code))
1786 case RTX_UNARY:
1787 if (CONST_INT_P (XEXP (copy, 0))
1788 && GET_MODE (XEXP (orig, 0)) != VOIDmode)
1790 scopy = simplify_unary_operation (code, mode, XEXP (copy, 0),
1791 GET_MODE (XEXP (orig, 0)));
1792 if (scopy)
1793 return scopy;
1795 break;
1796 case RTX_COMM_ARITH:
1797 case RTX_BIN_ARITH:
1798 /* These expressions can derive operand modes from the whole rtx's mode. */
1799 break;
1800 case RTX_TERNARY:
1801 case RTX_BITFIELD_OPS:
1802 if (CONST_INT_P (XEXP (copy, 0))
1803 && GET_MODE (XEXP (orig, 0)) != VOIDmode)
1805 scopy = simplify_ternary_operation (code, mode,
1806 GET_MODE (XEXP (orig, 0)),
1807 XEXP (copy, 0), XEXP (copy, 1),
1808 XEXP (copy, 2));
1809 if (scopy)
1810 return scopy;
1812 break;
1813 case RTX_COMPARE:
1814 case RTX_COMM_COMPARE:
1815 if (CONST_INT_P (XEXP (copy, 0))
1816 && GET_MODE (XEXP (copy, 1)) == VOIDmode
1817 && (GET_MODE (XEXP (orig, 0)) != VOIDmode
1818 || GET_MODE (XEXP (orig, 1)) != VOIDmode))
1820 scopy = simplify_relational_operation (code, mode,
1821 (GET_MODE (XEXP (orig, 0))
1822 != VOIDmode)
1823 ? GET_MODE (XEXP (orig, 0))
1824 : GET_MODE (XEXP (orig, 1)),
1825 XEXP (copy, 0),
1826 XEXP (copy, 1));
1827 if (scopy)
1828 return scopy;
1830 break;
1831 default:
1832 break;
1834 scopy = simplify_rtx (copy);
1835 if (scopy)
1836 return scopy;
1837 return copy;
1840 /* Walk rtx X and replace all occurrences of REG and MEM subexpressions
1841 with VALUE expressions. This way, it becomes independent of changes
1842 to registers and memory.
1843 X isn't actually modified; if modifications are needed, new rtl is
1844 allocated. However, the return value can share rtl with X.
1845 If X is within a MEM, MEMMODE must be the mode of the MEM. */
1848 cselib_subst_to_values (rtx x, machine_mode memmode)
1850 enum rtx_code code = GET_CODE (x);
1851 const char *fmt = GET_RTX_FORMAT (code);
1852 cselib_val *e;
1853 struct elt_list *l;
1854 rtx copy = x;
1855 int i;
1857 switch (code)
1859 case REG:
1860 l = REG_VALUES (REGNO (x));
1861 if (l && l->elt == NULL)
1862 l = l->next;
1863 for (; l; l = l->next)
1864 if (GET_MODE (l->elt->val_rtx) == GET_MODE (x))
1865 return l->elt->val_rtx;
1867 gcc_unreachable ();
1869 case MEM:
1870 e = cselib_lookup_mem (x, 0);
1871 /* This used to happen for autoincrements, but we deal with them
1872 properly now. Remove the if stmt for the next release. */
1873 if (! e)
1875 /* Assign a value that doesn't match any other. */
1876 e = new_cselib_val (next_uid, GET_MODE (x), x);
1878 return e->val_rtx;
1880 case ENTRY_VALUE:
1881 e = cselib_lookup (x, GET_MODE (x), 0, memmode);
1882 if (! e)
1883 break;
1884 return e->val_rtx;
1886 CASE_CONST_ANY:
1887 return x;
1889 case PRE_DEC:
1890 case PRE_INC:
1891 gcc_assert (memmode != VOIDmode);
1892 i = GET_MODE_SIZE (memmode);
1893 if (code == PRE_DEC)
1894 i = -i;
1895 return cselib_subst_to_values (plus_constant (GET_MODE (x),
1896 XEXP (x, 0), i),
1897 memmode);
1899 case PRE_MODIFY:
1900 gcc_assert (memmode != VOIDmode);
1901 return cselib_subst_to_values (XEXP (x, 1), memmode);
1903 case POST_DEC:
1904 case POST_INC:
1905 case POST_MODIFY:
1906 gcc_assert (memmode != VOIDmode);
1907 return cselib_subst_to_values (XEXP (x, 0), memmode);
1909 default:
1910 break;
1913 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1915 if (fmt[i] == 'e')
1917 rtx t = cselib_subst_to_values (XEXP (x, i), memmode);
1919 if (t != XEXP (x, i))
1921 if (x == copy)
1922 copy = shallow_copy_rtx (x);
1923 XEXP (copy, i) = t;
1926 else if (fmt[i] == 'E')
1928 int j;
1930 for (j = 0; j < XVECLEN (x, i); j++)
1932 rtx t = cselib_subst_to_values (XVECEXP (x, i, j), memmode);
1934 if (t != XVECEXP (x, i, j))
1936 if (XVEC (x, i) == XVEC (copy, i))
1938 if (x == copy)
1939 copy = shallow_copy_rtx (x);
1940 XVEC (copy, i) = shallow_copy_rtvec (XVEC (x, i));
1942 XVECEXP (copy, i, j) = t;
1948 return copy;
1951 /* Wrapper for cselib_subst_to_values, that indicates X is in INSN. */
1954 cselib_subst_to_values_from_insn (rtx x, machine_mode memmode, rtx_insn *insn)
1956 rtx ret;
1957 gcc_assert (!cselib_current_insn);
1958 cselib_current_insn = insn;
1959 ret = cselib_subst_to_values (x, memmode);
1960 cselib_current_insn = NULL;
1961 return ret;
1964 /* Look up the rtl expression X in our tables and return the value it
1965 has. If CREATE is zero, we return NULL if we don't know the value.
1966 Otherwise, we create a new one if possible, using mode MODE if X
1967 doesn't have a mode (i.e. because it's a constant). When X is part
1968 of an address, MEMMODE should be the mode of the enclosing MEM if
1969 we're tracking autoinc expressions. */
1971 static cselib_val *
1972 cselib_lookup_1 (rtx x, machine_mode mode,
1973 int create, machine_mode memmode)
1975 cselib_val **slot;
1976 cselib_val *e;
1977 unsigned int hashval;
1979 if (GET_MODE (x) != VOIDmode)
1980 mode = GET_MODE (x);
1982 if (GET_CODE (x) == VALUE)
1983 return CSELIB_VAL_PTR (x);
1985 if (REG_P (x))
1987 struct elt_list *l;
1988 unsigned int i = REGNO (x);
1990 l = REG_VALUES (i);
1991 if (l && l->elt == NULL)
1992 l = l->next;
1993 for (; l; l = l->next)
1994 if (mode == GET_MODE (l->elt->val_rtx))
1996 promote_debug_loc (l->elt->locs);
1997 return l->elt;
2000 if (! create)
2001 return 0;
2003 if (i < FIRST_PSEUDO_REGISTER)
2005 unsigned int n = hard_regno_nregs (i, mode);
2007 if (n > max_value_regs)
2008 max_value_regs = n;
2011 e = new_cselib_val (next_uid, GET_MODE (x), x);
2012 new_elt_loc_list (e, x);
2014 scalar_int_mode int_mode;
2015 if (REG_VALUES (i) == 0)
2017 /* Maintain the invariant that the first entry of
2018 REG_VALUES, if present, must be the value used to set the
2019 register, or NULL. */
2020 used_regs[n_used_regs++] = i;
2021 REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL);
2023 else if (cselib_preserve_constants
2024 && is_int_mode (mode, &int_mode))
2026 /* During var-tracking, try harder to find equivalences
2027 for SUBREGs. If a setter sets say a DImode register
2028 and user uses that register only in SImode, add a lowpart
2029 subreg location. */
2030 struct elt_list *lwider = NULL;
2031 scalar_int_mode lmode;
2032 l = REG_VALUES (i);
2033 if (l && l->elt == NULL)
2034 l = l->next;
2035 for (; l; l = l->next)
2036 if (is_int_mode (GET_MODE (l->elt->val_rtx), &lmode)
2037 && GET_MODE_SIZE (lmode) > GET_MODE_SIZE (int_mode)
2038 && (lwider == NULL
2039 || partial_subreg_p (lmode,
2040 GET_MODE (lwider->elt->val_rtx))))
2042 struct elt_loc_list *el;
2043 if (i < FIRST_PSEUDO_REGISTER
2044 && hard_regno_nregs (i, lmode) != 1)
2045 continue;
2046 for (el = l->elt->locs; el; el = el->next)
2047 if (!REG_P (el->loc))
2048 break;
2049 if (el)
2050 lwider = l;
2052 if (lwider)
2054 rtx sub = lowpart_subreg (int_mode, lwider->elt->val_rtx,
2055 GET_MODE (lwider->elt->val_rtx));
2056 if (sub)
2057 new_elt_loc_list (e, sub);
2060 REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e);
2061 slot = cselib_find_slot (mode, x, e->hash, INSERT, memmode);
2062 *slot = e;
2063 return e;
2066 if (MEM_P (x))
2067 return cselib_lookup_mem (x, create);
2069 hashval = cselib_hash_rtx (x, create, memmode);
2070 /* Can't even create if hashing is not possible. */
2071 if (! hashval)
2072 return 0;
2074 slot = cselib_find_slot (mode, x, hashval,
2075 create ? INSERT : NO_INSERT, memmode);
2076 if (slot == 0)
2077 return 0;
2079 e = (cselib_val *) *slot;
2080 if (e)
2081 return e;
2083 e = new_cselib_val (hashval, mode, x);
2085 /* We have to fill the slot before calling cselib_subst_to_values:
2086 the hash table is inconsistent until we do so, and
2087 cselib_subst_to_values will need to do lookups. */
2088 *slot = e;
2089 new_elt_loc_list (e, cselib_subst_to_values (x, memmode));
2090 return e;
2093 /* Wrapper for cselib_lookup, that indicates X is in INSN. */
2095 cselib_val *
2096 cselib_lookup_from_insn (rtx x, machine_mode mode,
2097 int create, machine_mode memmode, rtx_insn *insn)
2099 cselib_val *ret;
2101 gcc_assert (!cselib_current_insn);
2102 cselib_current_insn = insn;
2104 ret = cselib_lookup (x, mode, create, memmode);
2106 cselib_current_insn = NULL;
2108 return ret;
2111 /* Wrapper for cselib_lookup_1, that logs the lookup result and
2112 maintains invariants related with debug insns. */
2114 cselib_val *
2115 cselib_lookup (rtx x, machine_mode mode,
2116 int create, machine_mode memmode)
2118 cselib_val *ret = cselib_lookup_1 (x, mode, create, memmode);
2120 /* ??? Should we return NULL if we're not to create an entry, the
2121 found loc is a debug loc and cselib_current_insn is not DEBUG?
2122 If so, we should also avoid converting val to non-DEBUG; probably
2123 easiest setting cselib_current_insn to NULL before the call
2124 above. */
2126 if (dump_file && (dump_flags & TDF_CSELIB))
2128 fputs ("cselib lookup ", dump_file);
2129 print_inline_rtx (dump_file, x, 2);
2130 fprintf (dump_file, " => %u:%u\n",
2131 ret ? ret->uid : 0,
2132 ret ? ret->hash : 0);
2135 return ret;
2138 /* Invalidate any entries in reg_values that overlap REGNO. This is called
2139 if REGNO is changing. MODE is the mode of the assignment to REGNO, which
2140 is used to determine how many hard registers are being changed. If MODE
2141 is VOIDmode, then only REGNO is being changed; this is used when
2142 invalidating call clobbered registers across a call. */
2144 static void
2145 cselib_invalidate_regno (unsigned int regno, machine_mode mode)
2147 unsigned int endregno;
2148 unsigned int i;
2150 /* If we see pseudos after reload, something is _wrong_. */
2151 gcc_assert (!reload_completed || regno < FIRST_PSEUDO_REGISTER
2152 || reg_renumber[regno] < 0);
2154 /* Determine the range of registers that must be invalidated. For
2155 pseudos, only REGNO is affected. For hard regs, we must take MODE
2156 into account, and we must also invalidate lower register numbers
2157 if they contain values that overlap REGNO. */
2158 if (regno < FIRST_PSEUDO_REGISTER)
2160 gcc_assert (mode != VOIDmode);
2162 if (regno < max_value_regs)
2163 i = 0;
2164 else
2165 i = regno - max_value_regs;
2167 endregno = end_hard_regno (mode, regno);
2169 else
2171 i = regno;
2172 endregno = regno + 1;
2175 for (; i < endregno; i++)
2177 struct elt_list **l = &REG_VALUES (i);
2179 /* Go through all known values for this reg; if it overlaps the range
2180 we're invalidating, remove the value. */
2181 while (*l)
2183 cselib_val *v = (*l)->elt;
2184 bool had_locs;
2185 rtx_insn *setting_insn;
2186 struct elt_loc_list **p;
2187 unsigned int this_last = i;
2189 if (i < FIRST_PSEUDO_REGISTER && v != NULL)
2190 this_last = end_hard_regno (GET_MODE (v->val_rtx), i) - 1;
2192 if (this_last < regno || v == NULL
2193 || (v == cfa_base_preserved_val
2194 && i == cfa_base_preserved_regno))
2196 l = &(*l)->next;
2197 continue;
2200 /* We have an overlap. */
2201 if (*l == REG_VALUES (i))
2203 /* Maintain the invariant that the first entry of
2204 REG_VALUES, if present, must be the value used to set
2205 the register, or NULL. This is also nice because
2206 then we won't push the same regno onto user_regs
2207 multiple times. */
2208 (*l)->elt = NULL;
2209 l = &(*l)->next;
2211 else
2212 unchain_one_elt_list (l);
2214 v = canonical_cselib_val (v);
2216 had_locs = v->locs != NULL;
2217 setting_insn = v->locs ? v->locs->setting_insn : NULL;
2219 /* Now, we clear the mapping from value to reg. It must exist, so
2220 this code will crash intentionally if it doesn't. */
2221 for (p = &v->locs; ; p = &(*p)->next)
2223 rtx x = (*p)->loc;
2225 if (REG_P (x) && REGNO (x) == i)
2227 unchain_one_elt_loc_list (p);
2228 break;
2232 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
2234 if (setting_insn && DEBUG_INSN_P (setting_insn))
2235 n_useless_debug_values++;
2236 else
2237 n_useless_values++;
2243 /* Invalidate any locations in the table which are changed because of a
2244 store to MEM_RTX. If this is called because of a non-const call
2245 instruction, MEM_RTX is (mem:BLK const0_rtx). */
2247 static void
2248 cselib_invalidate_mem (rtx mem_rtx)
2250 cselib_val **vp, *v, *next;
2251 int num_mems = 0;
2252 rtx mem_addr;
2254 mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
2255 mem_rtx = canon_rtx (mem_rtx);
2257 vp = &first_containing_mem;
2258 for (v = *vp; v != &dummy_val; v = next)
2260 bool has_mem = false;
2261 struct elt_loc_list **p = &v->locs;
2262 bool had_locs = v->locs != NULL;
2263 rtx_insn *setting_insn = v->locs ? v->locs->setting_insn : NULL;
2265 while (*p)
2267 rtx x = (*p)->loc;
2268 cselib_val *addr;
2269 struct elt_list **mem_chain;
2271 /* MEMs may occur in locations only at the top level; below
2272 that every MEM or REG is substituted by its VALUE. */
2273 if (!MEM_P (x))
2275 p = &(*p)->next;
2276 continue;
2278 if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
2279 && ! canon_anti_dependence (x, false, mem_rtx,
2280 GET_MODE (mem_rtx), mem_addr))
2282 has_mem = true;
2283 num_mems++;
2284 p = &(*p)->next;
2285 continue;
2288 /* This one overlaps. */
2289 /* We must have a mapping from this MEM's address to the
2290 value (E). Remove that, too. */
2291 addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0, GET_MODE (x));
2292 addr = canonical_cselib_val (addr);
2293 gcc_checking_assert (v == canonical_cselib_val (v));
2294 mem_chain = &addr->addr_list;
2295 for (;;)
2297 cselib_val *canon = canonical_cselib_val ((*mem_chain)->elt);
2299 if (canon == v)
2301 unchain_one_elt_list (mem_chain);
2302 break;
2305 /* Record canonicalized elt. */
2306 (*mem_chain)->elt = canon;
2308 mem_chain = &(*mem_chain)->next;
2311 unchain_one_elt_loc_list (p);
2314 if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
2316 if (setting_insn && DEBUG_INSN_P (setting_insn))
2317 n_useless_debug_values++;
2318 else
2319 n_useless_values++;
2322 next = v->next_containing_mem;
2323 if (has_mem)
2325 *vp = v;
2326 vp = &(*vp)->next_containing_mem;
2328 else
2329 v->next_containing_mem = NULL;
2331 *vp = &dummy_val;
2334 /* Invalidate DEST, which is being assigned to or clobbered. */
2336 void
2337 cselib_invalidate_rtx (rtx dest)
2339 while (GET_CODE (dest) == SUBREG
2340 || GET_CODE (dest) == ZERO_EXTRACT
2341 || GET_CODE (dest) == STRICT_LOW_PART)
2342 dest = XEXP (dest, 0);
2344 if (REG_P (dest))
2345 cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
2346 else if (MEM_P (dest))
2347 cselib_invalidate_mem (dest);
2350 /* A wrapper for cselib_invalidate_rtx to be called via note_stores. */
2352 static void
2353 cselib_invalidate_rtx_note_stores (rtx dest, const_rtx ignore ATTRIBUTE_UNUSED,
2354 void *data ATTRIBUTE_UNUSED)
2356 cselib_invalidate_rtx (dest);
2359 /* Record the result of a SET instruction. DEST is being set; the source
2360 contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT
2361 describes its address. */
2363 static void
2364 cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
2366 if (src_elt == 0 || side_effects_p (dest))
2367 return;
2369 if (REG_P (dest))
2371 unsigned int dreg = REGNO (dest);
2372 if (dreg < FIRST_PSEUDO_REGISTER)
2374 unsigned int n = REG_NREGS (dest);
2376 if (n > max_value_regs)
2377 max_value_regs = n;
2380 if (REG_VALUES (dreg) == 0)
2382 used_regs[n_used_regs++] = dreg;
2383 REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
2385 else
2387 /* The register should have been invalidated. */
2388 gcc_assert (REG_VALUES (dreg)->elt == 0);
2389 REG_VALUES (dreg)->elt = src_elt;
2392 if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
2393 n_useless_values--;
2394 new_elt_loc_list (src_elt, dest);
2396 else if (MEM_P (dest) && dest_addr_elt != 0
2397 && cselib_record_memory)
2399 if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
2400 n_useless_values--;
2401 add_mem_for_addr (dest_addr_elt, src_elt, dest);
2405 /* Make ELT and X's VALUE equivalent to each other at INSN. */
2407 void
2408 cselib_add_permanent_equiv (cselib_val *elt, rtx x, rtx_insn *insn)
2410 cselib_val *nelt;
2411 rtx_insn *save_cselib_current_insn = cselib_current_insn;
2413 gcc_checking_assert (elt);
2414 gcc_checking_assert (PRESERVED_VALUE_P (elt->val_rtx));
2415 gcc_checking_assert (!side_effects_p (x));
2417 cselib_current_insn = insn;
2419 nelt = cselib_lookup (x, GET_MODE (elt->val_rtx), 1, VOIDmode);
2421 if (nelt != elt)
2423 cselib_any_perm_equivs = true;
2425 if (!PRESERVED_VALUE_P (nelt->val_rtx))
2426 cselib_preserve_value (nelt);
2428 new_elt_loc_list (nelt, elt->val_rtx);
2431 cselib_current_insn = save_cselib_current_insn;
2434 /* Return TRUE if any permanent equivalences have been recorded since
2435 the table was last initialized. */
2436 bool
2437 cselib_have_permanent_equivalences (void)
2439 return cselib_any_perm_equivs;
2442 /* There is no good way to determine how many elements there can be
2443 in a PARALLEL. Since it's fairly cheap, use a really large number. */
2444 #define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
2446 struct cselib_record_autoinc_data
2448 struct cselib_set *sets;
2449 int n_sets;
2452 /* Callback for for_each_inc_dec. Records in ARG the SETs implied by
2453 autoinc RTXs: SRC plus SRCOFF if non-NULL is stored in DEST. */
2455 static int
2456 cselib_record_autoinc_cb (rtx mem ATTRIBUTE_UNUSED, rtx op ATTRIBUTE_UNUSED,
2457 rtx dest, rtx src, rtx srcoff, void *arg)
2459 struct cselib_record_autoinc_data *data;
2460 data = (struct cselib_record_autoinc_data *)arg;
2462 data->sets[data->n_sets].dest = dest;
2464 if (srcoff)
2465 data->sets[data->n_sets].src = gen_rtx_PLUS (GET_MODE (src), src, srcoff);
2466 else
2467 data->sets[data->n_sets].src = src;
2469 data->n_sets++;
2471 return 0;
2474 /* Record the effects of any sets and autoincs in INSN. */
2475 static void
2476 cselib_record_sets (rtx_insn *insn)
2478 int n_sets = 0;
2479 int i;
2480 struct cselib_set sets[MAX_SETS];
2481 rtx body = PATTERN (insn);
2482 rtx cond = 0;
2483 int n_sets_before_autoinc;
2484 struct cselib_record_autoinc_data data;
2486 body = PATTERN (insn);
2487 if (GET_CODE (body) == COND_EXEC)
2489 cond = COND_EXEC_TEST (body);
2490 body = COND_EXEC_CODE (body);
2493 /* Find all sets. */
2494 if (GET_CODE (body) == SET)
2496 sets[0].src = SET_SRC (body);
2497 sets[0].dest = SET_DEST (body);
2498 n_sets = 1;
2500 else if (GET_CODE (body) == PARALLEL)
2502 /* Look through the PARALLEL and record the values being
2503 set, if possible. Also handle any CLOBBERs. */
2504 for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
2506 rtx x = XVECEXP (body, 0, i);
2508 if (GET_CODE (x) == SET)
2510 sets[n_sets].src = SET_SRC (x);
2511 sets[n_sets].dest = SET_DEST (x);
2512 n_sets++;
2517 if (n_sets == 1
2518 && MEM_P (sets[0].src)
2519 && !cselib_record_memory
2520 && MEM_READONLY_P (sets[0].src))
2522 rtx note = find_reg_equal_equiv_note (insn);
2524 if (note && CONSTANT_P (XEXP (note, 0)))
2525 sets[0].src = XEXP (note, 0);
2528 data.sets = sets;
2529 data.n_sets = n_sets_before_autoinc = n_sets;
2530 for_each_inc_dec (PATTERN (insn), cselib_record_autoinc_cb, &data);
2531 n_sets = data.n_sets;
2533 /* Look up the values that are read. Do this before invalidating the
2534 locations that are written. */
2535 for (i = 0; i < n_sets; i++)
2537 rtx dest = sets[i].dest;
2539 /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
2540 the low part after invalidating any knowledge about larger modes. */
2541 if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
2542 sets[i].dest = dest = XEXP (dest, 0);
2544 /* We don't know how to record anything but REG or MEM. */
2545 if (REG_P (dest)
2546 || (MEM_P (dest) && cselib_record_memory))
2548 rtx src = sets[i].src;
2549 if (cond)
2550 src = gen_rtx_IF_THEN_ELSE (GET_MODE (dest), cond, src, dest);
2551 sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1, VOIDmode);
2552 if (MEM_P (dest))
2554 machine_mode address_mode = get_address_mode (dest);
2556 sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0),
2557 address_mode, 1,
2558 GET_MODE (dest));
2560 else
2561 sets[i].dest_addr_elt = 0;
2565 if (cselib_record_sets_hook)
2566 cselib_record_sets_hook (insn, sets, n_sets);
2568 /* Invalidate all locations written by this insn. Note that the elts we
2569 looked up in the previous loop aren't affected, just some of their
2570 locations may go away. */
2571 note_stores (body, cselib_invalidate_rtx_note_stores, NULL);
2573 for (i = n_sets_before_autoinc; i < n_sets; i++)
2574 cselib_invalidate_rtx (sets[i].dest);
2576 /* If this is an asm, look for duplicate sets. This can happen when the
2577 user uses the same value as an output multiple times. This is valid
2578 if the outputs are not actually used thereafter. Treat this case as
2579 if the value isn't actually set. We do this by smashing the destination
2580 to pc_rtx, so that we won't record the value later. */
2581 if (n_sets >= 2 && asm_noperands (body) >= 0)
2583 for (i = 0; i < n_sets; i++)
2585 rtx dest = sets[i].dest;
2586 if (REG_P (dest) || MEM_P (dest))
2588 int j;
2589 for (j = i + 1; j < n_sets; j++)
2590 if (rtx_equal_p (dest, sets[j].dest))
2592 sets[i].dest = pc_rtx;
2593 sets[j].dest = pc_rtx;
2599 /* Now enter the equivalences in our tables. */
2600 for (i = 0; i < n_sets; i++)
2602 rtx dest = sets[i].dest;
2603 if (REG_P (dest)
2604 || (MEM_P (dest) && cselib_record_memory))
2605 cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
2609 /* Return true if INSN in the prologue initializes hard_frame_pointer_rtx. */
2611 bool
2612 fp_setter_insn (rtx_insn *insn)
2614 rtx expr, pat = NULL_RTX;
2616 if (!RTX_FRAME_RELATED_P (insn))
2617 return false;
2619 expr = find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX);
2620 if (expr)
2621 pat = XEXP (expr, 0);
2622 if (!modified_in_p (hard_frame_pointer_rtx, pat ? pat : insn))
2623 return false;
2625 /* Don't return true for frame pointer restores in the epilogue. */
2626 if (find_reg_note (insn, REG_CFA_RESTORE, hard_frame_pointer_rtx))
2627 return false;
2628 return true;
2631 /* Record the effects of INSN. */
2633 void
2634 cselib_process_insn (rtx_insn *insn)
2636 int i;
2637 rtx x;
2639 cselib_current_insn = insn;
2641 /* Forget everything at a CODE_LABEL or a setjmp. */
2642 if ((LABEL_P (insn)
2643 || (CALL_P (insn)
2644 && find_reg_note (insn, REG_SETJMP, NULL)))
2645 && !cselib_preserve_constants)
2647 cselib_reset_table (next_uid);
2648 cselib_current_insn = NULL;
2649 return;
2652 if (! INSN_P (insn))
2654 cselib_current_insn = NULL;
2655 return;
2658 /* If this is a call instruction, forget anything stored in a
2659 call clobbered register, or, if this is not a const call, in
2660 memory. */
2661 if (CALL_P (insn))
2663 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2664 if (call_used_regs[i]
2665 || (REG_VALUES (i) && REG_VALUES (i)->elt
2666 && (targetm.hard_regno_call_part_clobbered
2667 (i, GET_MODE (REG_VALUES (i)->elt->val_rtx)))))
2668 cselib_invalidate_regno (i, reg_raw_mode[i]);
2670 /* Since it is not clear how cselib is going to be used, be
2671 conservative here and treat looping pure or const functions
2672 as if they were regular functions. */
2673 if (RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
2674 || !(RTL_CONST_OR_PURE_CALL_P (insn)))
2675 cselib_invalidate_mem (callmem);
2676 else
2677 /* For const/pure calls, invalidate any argument slots because
2678 they are owned by the callee. */
2679 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
2680 if (GET_CODE (XEXP (x, 0)) == USE
2681 && MEM_P (XEXP (XEXP (x, 0), 0)))
2682 cselib_invalidate_mem (XEXP (XEXP (x, 0), 0));
2685 cselib_record_sets (insn);
2687 /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
2688 after we have processed the insn. */
2689 if (CALL_P (insn))
2691 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
2692 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
2693 cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0));
2694 /* Flush evertything on setjmp. */
2695 if (cselib_preserve_constants
2696 && find_reg_note (insn, REG_SETJMP, NULL))
2698 cselib_preserve_only_values ();
2699 cselib_reset_table (next_uid);
2703 /* On setter of the hard frame pointer if frame_pointer_needed,
2704 invalidate stack_pointer_rtx, so that sp and {,h}fp based
2705 VALUEs are distinct. */
2706 if (reload_completed
2707 && frame_pointer_needed
2708 && fp_setter_insn (insn))
2709 cselib_invalidate_rtx (stack_pointer_rtx);
2711 cselib_current_insn = NULL;
2713 if (n_useless_values > MAX_USELESS_VALUES
2714 /* remove_useless_values is linear in the hash table size. Avoid
2715 quadratic behavior for very large hashtables with very few
2716 useless elements. */
2717 && ((unsigned int)n_useless_values
2718 > (cselib_hash_table->elements () - n_debug_values) / 4))
2719 remove_useless_values ();
2722 /* Initialize cselib for one pass. The caller must also call
2723 init_alias_analysis. */
2725 void
2726 cselib_init (int record_what)
2728 cselib_record_memory = record_what & CSELIB_RECORD_MEMORY;
2729 cselib_preserve_constants = record_what & CSELIB_PRESERVE_CONSTANTS;
2730 cselib_any_perm_equivs = false;
2732 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything,
2733 see canon_true_dependence. This is only created once. */
2734 if (! callmem)
2735 callmem = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode));
2737 cselib_nregs = max_reg_num ();
2739 /* We preserve reg_values to allow expensive clearing of the whole thing.
2740 Reallocate it however if it happens to be too large. */
2741 if (!reg_values || reg_values_size < cselib_nregs
2742 || (reg_values_size > 10 && reg_values_size > cselib_nregs * 4))
2744 free (reg_values);
2745 /* Some space for newly emit instructions so we don't end up
2746 reallocating in between passes. */
2747 reg_values_size = cselib_nregs + (63 + cselib_nregs) / 16;
2748 reg_values = XCNEWVEC (struct elt_list *, reg_values_size);
2750 used_regs = XNEWVEC (unsigned int, cselib_nregs);
2751 n_used_regs = 0;
2752 cselib_hash_table = new hash_table<cselib_hasher> (31);
2753 if (cselib_preserve_constants)
2754 cselib_preserved_hash_table = new hash_table<cselib_hasher> (31);
2755 next_uid = 1;
2758 /* Called when the current user is done with cselib. */
2760 void
2761 cselib_finish (void)
2763 bool preserved = cselib_preserve_constants;
2764 cselib_discard_hook = NULL;
2765 cselib_preserve_constants = false;
2766 cselib_any_perm_equivs = false;
2767 cfa_base_preserved_val = NULL;
2768 cfa_base_preserved_regno = INVALID_REGNUM;
2769 elt_list_pool.release ();
2770 elt_loc_list_pool.release ();
2771 cselib_val_pool.release ();
2772 value_pool.release ();
2773 cselib_clear_table ();
2774 delete cselib_hash_table;
2775 cselib_hash_table = NULL;
2776 if (preserved)
2777 delete cselib_preserved_hash_table;
2778 cselib_preserved_hash_table = NULL;
2779 free (used_regs);
2780 used_regs = 0;
2781 n_useless_values = 0;
2782 n_useless_debug_values = 0;
2783 n_debug_values = 0;
2784 next_uid = 0;
2787 /* Dump the cselib_val *X to FILE *OUT. */
2790 dump_cselib_val (cselib_val **x, FILE *out)
2792 cselib_val *v = *x;
2793 bool need_lf = true;
2795 print_inline_rtx (out, v->val_rtx, 0);
2797 if (v->locs)
2799 struct elt_loc_list *l = v->locs;
2800 if (need_lf)
2802 fputc ('\n', out);
2803 need_lf = false;
2805 fputs (" locs:", out);
2808 if (l->setting_insn)
2809 fprintf (out, "\n from insn %i ",
2810 INSN_UID (l->setting_insn));
2811 else
2812 fprintf (out, "\n ");
2813 print_inline_rtx (out, l->loc, 4);
2815 while ((l = l->next));
2816 fputc ('\n', out);
2818 else
2820 fputs (" no locs", out);
2821 need_lf = true;
2824 if (v->addr_list)
2826 struct elt_list *e = v->addr_list;
2827 if (need_lf)
2829 fputc ('\n', out);
2830 need_lf = false;
2832 fputs (" addr list:", out);
2835 fputs ("\n ", out);
2836 print_inline_rtx (out, e->elt->val_rtx, 2);
2838 while ((e = e->next));
2839 fputc ('\n', out);
2841 else
2843 fputs (" no addrs", out);
2844 need_lf = true;
2847 if (v->next_containing_mem == &dummy_val)
2848 fputs (" last mem\n", out);
2849 else if (v->next_containing_mem)
2851 fputs (" next mem ", out);
2852 print_inline_rtx (out, v->next_containing_mem->val_rtx, 2);
2853 fputc ('\n', out);
2855 else if (need_lf)
2856 fputc ('\n', out);
2858 return 1;
2861 /* Dump to OUT everything in the CSELIB table. */
2863 void
2864 dump_cselib_table (FILE *out)
2866 fprintf (out, "cselib hash table:\n");
2867 cselib_hash_table->traverse <FILE *, dump_cselib_val> (out);
2868 fprintf (out, "cselib preserved hash table:\n");
2869 cselib_preserved_hash_table->traverse <FILE *, dump_cselib_val> (out);
2870 if (first_containing_mem != &dummy_val)
2872 fputs ("first mem ", out);
2873 print_inline_rtx (out, first_containing_mem->val_rtx, 2);
2874 fputc ('\n', out);
2876 fprintf (out, "next uid %i\n", next_uid);
2879 #include "gt-cselib.h"