1 /* Common subexpression elimination library for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
24 #include "coretypes.h"
30 #include "hard-reg-set.h"
33 #include "insn-config.h"
43 #include "alloc-pool.h"
45 static int entry_and_rtx_equal_p (const void *, const void *);
46 static hashval_t get_value_hash (const void *);
47 static struct elt_list *new_elt_list (struct elt_list *, cselib_val *);
48 static struct elt_loc_list *new_elt_loc_list (struct elt_loc_list *, 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 clear_table (void);
53 static int discard_useless_locs (void **, void *);
54 static int discard_useless_values (void **, void *);
55 static void remove_useless_values (void);
56 static rtx wrap_constant (enum machine_mode, rtx);
57 static unsigned int hash_rtx (rtx, enum machine_mode, int);
58 static cselib_val *new_cselib_val (unsigned int, enum machine_mode);
59 static void add_mem_for_addr (cselib_val *, cselib_val *, rtx);
60 static cselib_val *cselib_lookup_mem (rtx, int);
61 static void cselib_invalidate_regno (unsigned int, enum machine_mode);
62 static void cselib_invalidate_mem (rtx);
63 static void cselib_invalidate_rtx (rtx, rtx, void *);
64 static void cselib_record_set (rtx, cselib_val *, cselib_val *);
65 static void cselib_record_sets (rtx);
67 /* There are three ways in which cselib can look up an rtx:
68 - for a REG, the reg_values table (which is indexed by regno) is used
69 - for a MEM, we recursively look up its address and then follow the
70 addr_list of that value
71 - for everything else, we compute a hash value and go through the hash
72 table. Since different rtx's can still have the same hash value,
73 this involves walking the table entries for a given value and comparing
74 the locations of the entries with the rtx we are looking up. */
76 /* A table that enables us to look up elts by their value. */
77 static GTY((param_is (cselib_val))) htab_t hash_table;
79 /* This is a global so we don't have to pass this through every function.
80 It is used in new_elt_loc_list to set SETTING_INSN. */
81 static rtx cselib_current_insn;
82 static bool cselib_current_insn_in_libcall;
84 /* Every new unknown value gets a unique number. */
85 static unsigned int next_unknown_value;
87 /* The number of registers we had when the varrays were last resized. */
88 static unsigned int cselib_nregs;
90 /* Count values without known locations. Whenever this grows too big, we
91 remove these useless values from the table. */
92 static int n_useless_values;
94 /* Number of useless values before we remove them from the hash table. */
95 #define MAX_USELESS_VALUES 32
97 /* This table maps from register number to values. It does not
98 contain pointers to cselib_val structures, but rather elt_lists.
99 The purpose is to be able to refer to the same register in
100 different modes. The first element of the list defines the mode in
101 which the register was set; if the mode is unknown or the value is
102 no longer valid in that mode, ELT will be NULL for the first
104 static GTY(()) varray_type reg_values;
105 static GTY((deletable (""))) varray_type reg_values_old;
106 #define REG_VALUES(I) VARRAY_ELT_LIST (reg_values, (I))
108 /* The largest number of hard regs used by any entry added to the
109 REG_VALUES table. Cleared on each clear_table() invocation. */
110 static unsigned int max_value_regs;
112 /* Here the set of indices I with REG_VALUES(I) != 0 is saved. This is used
113 in clear_table() for fast emptying. */
114 static GTY(()) varray_type used_regs;
115 static GTY((deletable (""))) varray_type used_regs_old;
117 /* We pass this to cselib_invalidate_mem to invalidate all of
118 memory for a non-const call instruction. */
119 static GTY(()) rtx callmem;
121 /* Set by discard_useless_locs if it deleted the last location of any
123 static int values_became_useless;
125 /* Used as stop element of the containing_mem list so we can check
126 presence in the list by checking the next pointer. */
127 static cselib_val dummy_val;
129 /* Used to list all values that contain memory reference.
130 May or may not contain the useless values - the list is compacted
131 each time memory is invalidated. */
132 static cselib_val *first_containing_mem = &dummy_val;
133 static alloc_pool elt_loc_list_pool, elt_list_pool, cselib_val_pool;
136 /* Allocate a struct elt_list and fill in its two elements with the
139 static inline struct elt_list *
140 new_elt_list (struct elt_list *next, cselib_val *elt)
143 el = pool_alloc (elt_list_pool);
149 /* Allocate a struct elt_loc_list and fill in its two elements with the
152 static inline struct elt_loc_list *
153 new_elt_loc_list (struct elt_loc_list *next, rtx loc)
155 struct elt_loc_list *el;
156 el = pool_alloc (elt_loc_list_pool);
159 el->canon_loc = NULL;
160 el->setting_insn = cselib_current_insn;
161 el->in_libcall = cselib_current_insn_in_libcall;
165 /* The elt_list at *PL is no longer needed. Unchain it and free its
169 unchain_one_elt_list (struct elt_list **pl)
171 struct elt_list *l = *pl;
174 pool_free (elt_list_pool, l);
177 /* Likewise for elt_loc_lists. */
180 unchain_one_elt_loc_list (struct elt_loc_list **pl)
182 struct elt_loc_list *l = *pl;
185 pool_free (elt_loc_list_pool, l);
188 /* Likewise for cselib_vals. This also frees the addr_list associated with
192 unchain_one_value (cselib_val *v)
195 unchain_one_elt_list (&v->addr_list);
197 pool_free (cselib_val_pool, v);
200 /* Remove all entries from the hash table. Also used during
201 initialization. If CLEAR_ALL isn't set, then only clear the entries
202 which are known to have been used. */
209 for (i = 0; i < VARRAY_ACTIVE_SIZE (used_regs); i++)
210 REG_VALUES (VARRAY_UINT (used_regs, i)) = 0;
214 VARRAY_POP_ALL (used_regs);
216 htab_empty (hash_table);
218 n_useless_values = 0;
220 next_unknown_value = 0;
222 first_containing_mem = &dummy_val;
225 /* The equality test for our hash table. The first argument ENTRY is a table
226 element (i.e. a cselib_val), while the second arg X is an rtx. We know
227 that all callers of htab_find_slot_with_hash will wrap CONST_INTs into a
228 CONST of an appropriate mode. */
231 entry_and_rtx_equal_p (const void *entry, const void *x_arg)
233 struct elt_loc_list *l;
234 const cselib_val *v = (const cselib_val *) entry;
236 enum machine_mode mode = GET_MODE (x);
238 if (GET_CODE (x) == CONST_INT
239 || (mode == VOIDmode && GET_CODE (x) == CONST_DOUBLE))
241 if (mode != GET_MODE (v->u.val_rtx))
244 /* Unwrap X if necessary. */
245 if (GET_CODE (x) == CONST
246 && (GET_CODE (XEXP (x, 0)) == CONST_INT
247 || GET_CODE (XEXP (x, 0)) == CONST_DOUBLE))
250 /* We don't guarantee that distinct rtx's have different hash values,
251 so we need to do a comparison. */
252 for (l = v->locs; l; l = l->next)
253 if (rtx_equal_for_cselib_p (l->loc, x))
259 /* The hash function for our hash table. The value is always computed with
260 hash_rtx when adding an element; this function just extracts the hash
261 value from a cselib_val structure. */
264 get_value_hash (const void *entry)
266 const cselib_val *v = (const cselib_val *) entry;
270 /* Return true if X contains a VALUE rtx. If ONLY_USELESS is set, we
271 only return true for values which point to a cselib_val whose value
272 element has been set to zero, which implies the cselib_val will be
276 references_value_p (rtx x, int only_useless)
278 enum rtx_code code = GET_CODE (x);
279 const char *fmt = GET_RTX_FORMAT (code);
282 if (GET_CODE (x) == VALUE
283 && (! only_useless || CSELIB_VAL_PTR (x)->locs == 0))
286 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
288 if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless))
290 else if (fmt[i] == 'E')
291 for (j = 0; j < XVECLEN (x, i); j++)
292 if (references_value_p (XVECEXP (x, i, j), only_useless))
299 /* For all locations found in X, delete locations that reference useless
300 values (i.e. values without any location). Called through
304 discard_useless_locs (void **x, void *info ATTRIBUTE_UNUSED)
306 cselib_val *v = (cselib_val *)*x;
307 struct elt_loc_list **p = &v->locs;
308 int had_locs = v->locs != 0;
312 if (references_value_p ((*p)->loc, 1))
313 unchain_one_elt_loc_list (p);
318 if (had_locs && v->locs == 0)
321 values_became_useless = 1;
326 /* If X is a value with no locations, remove it from the hashtable. */
329 discard_useless_values (void **x, void *info ATTRIBUTE_UNUSED)
331 cselib_val *v = (cselib_val *)*x;
335 htab_clear_slot (hash_table, x);
336 unchain_one_value (v);
343 /* Clean out useless values (i.e. those which no longer have locations
344 associated with them) from the hash table. */
347 remove_useless_values (void)
350 /* First pass: eliminate locations that reference the value. That in
351 turn can make more values useless. */
354 values_became_useless = 0;
355 htab_traverse (hash_table, discard_useless_locs, 0);
357 while (values_became_useless);
359 /* Second pass: actually remove the values. */
360 htab_traverse (hash_table, discard_useless_values, 0);
362 p = &first_containing_mem;
363 for (v = *p; v != &dummy_val; v = v->next_containing_mem)
367 p = &(*p)->next_containing_mem;
371 if (n_useless_values != 0)
375 /* Return the mode in which a register was last set. If X is not a
376 register, return its mode. If the mode in which the register was
377 set is not known, or the value was already clobbered, return
381 cselib_reg_set_mode (rtx x)
383 if (GET_CODE (x) != REG)
386 if (REG_VALUES (REGNO (x)) == NULL
387 || REG_VALUES (REGNO (x))->elt == NULL)
390 return GET_MODE (REG_VALUES (REGNO (x))->elt->u.val_rtx);
393 /* Return nonzero if we can prove that X and Y contain the same value, taking
394 our gathered information into account. */
397 rtx_equal_for_cselib_p (rtx x, rtx y)
403 if (GET_CODE (x) == REG || GET_CODE (x) == MEM)
405 cselib_val *e = cselib_lookup (x, GET_MODE (x), 0);
411 if (GET_CODE (y) == REG || GET_CODE (y) == MEM)
413 cselib_val *e = cselib_lookup (y, GET_MODE (y), 0);
422 if (GET_CODE (x) == VALUE && GET_CODE (y) == VALUE)
423 return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y);
425 if (GET_CODE (x) == VALUE)
427 cselib_val *e = CSELIB_VAL_PTR (x);
428 struct elt_loc_list *l;
430 for (l = e->locs; l; l = l->next)
434 /* Avoid infinite recursion. */
435 if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
437 else if (rtx_equal_for_cselib_p (t, y))
444 if (GET_CODE (y) == VALUE)
446 cselib_val *e = CSELIB_VAL_PTR (y);
447 struct elt_loc_list *l;
449 for (l = e->locs; l; l = l->next)
453 if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
455 else if (rtx_equal_for_cselib_p (x, t))
462 if (GET_CODE (x) != GET_CODE (y) || GET_MODE (x) != GET_MODE (y))
465 /* This won't be handled correctly by the code below. */
466 if (GET_CODE (x) == LABEL_REF)
467 return XEXP (x, 0) == XEXP (y, 0);
470 fmt = GET_RTX_FORMAT (code);
472 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
479 if (XWINT (x, i) != XWINT (y, i))
485 if (XINT (x, i) != XINT (y, i))
491 /* Two vectors must have the same length. */
492 if (XVECLEN (x, i) != XVECLEN (y, i))
495 /* And the corresponding elements must match. */
496 for (j = 0; j < XVECLEN (x, i); j++)
497 if (! rtx_equal_for_cselib_p (XVECEXP (x, i, j),
503 if (! rtx_equal_for_cselib_p (XEXP (x, i), XEXP (y, i)))
509 if (strcmp (XSTR (x, i), XSTR (y, i)))
514 /* These are just backpointers, so they don't matter. */
521 /* It is believed that rtx's at this level will never
522 contain anything but integers and other rtx's,
523 except for within LABEL_REFs and SYMBOL_REFs. */
531 /* We need to pass down the mode of constants through the hash table
532 functions. For that purpose, wrap them in a CONST of the appropriate
535 wrap_constant (enum machine_mode mode, rtx x)
537 if (GET_CODE (x) != CONST_INT
538 && (GET_CODE (x) != CONST_DOUBLE || GET_MODE (x) != VOIDmode))
540 if (mode == VOIDmode)
542 return gen_rtx_CONST (mode, x);
545 /* Hash an rtx. Return 0 if we couldn't hash the rtx.
546 For registers and memory locations, we look up their cselib_val structure
547 and return its VALUE element.
548 Possible reasons for return 0 are: the object is volatile, or we couldn't
549 find a register or memory location in the table and CREATE is zero. If
550 CREATE is nonzero, table elts are created for regs and mem.
551 MODE is used in hashing for CONST_INTs only;
552 otherwise the mode of X is used. */
555 hash_rtx (rtx x, enum machine_mode mode, int create)
561 unsigned int hash = 0;
564 hash += (unsigned) code + (unsigned) GET_MODE (x);
570 e = cselib_lookup (x, GET_MODE (x), create);
577 hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + INTVAL (x);
578 return hash ? hash : (unsigned int) CONST_INT;
581 /* This is like the general case, except that it only counts
582 the integers representing the constant. */
583 hash += (unsigned) code + (unsigned) GET_MODE (x);
584 if (GET_MODE (x) != VOIDmode)
585 hash += real_hash (CONST_DOUBLE_REAL_VALUE (x));
587 hash += ((unsigned) CONST_DOUBLE_LOW (x)
588 + (unsigned) CONST_DOUBLE_HIGH (x));
589 return hash ? hash : (unsigned int) CONST_DOUBLE;
596 units = CONST_VECTOR_NUNITS (x);
598 for (i = 0; i < units; ++i)
600 elt = CONST_VECTOR_ELT (x, i);
601 hash += hash_rtx (elt, GET_MODE (elt), 0);
607 /* Assume there is only one rtx object for any given label. */
610 += ((unsigned) LABEL_REF << 7) + (unsigned long) XEXP (x, 0);
611 return hash ? hash : (unsigned int) LABEL_REF;
615 += ((unsigned) SYMBOL_REF << 7) + (unsigned long) XSTR (x, 0);
616 return hash ? hash : (unsigned int) SYMBOL_REF;
627 case UNSPEC_VOLATILE:
631 if (MEM_VOLATILE_P (x))
640 i = GET_RTX_LENGTH (code) - 1;
641 fmt = GET_RTX_FORMAT (code);
646 rtx tem = XEXP (x, i);
647 unsigned int tem_hash = hash_rtx (tem, 0, create);
654 else if (fmt[i] == 'E')
655 for (j = 0; j < XVECLEN (x, i); j++)
657 unsigned int tem_hash = hash_rtx (XVECEXP (x, i, j), 0, create);
664 else if (fmt[i] == 's')
666 const unsigned char *p = (const unsigned char *) XSTR (x, i);
672 else if (fmt[i] == 'i')
674 else if (fmt[i] == '0' || fmt[i] == 't')
680 return hash ? hash : 1 + (unsigned int) GET_CODE (x);
683 /* Create a new value structure for VALUE and initialize it. The mode of the
686 static inline cselib_val *
687 new_cselib_val (unsigned int value, enum machine_mode mode)
689 cselib_val *e = pool_alloc (cselib_val_pool);
691 #ifdef ENABLE_CHECKING
697 e->u.val_rtx = gen_rtx_VALUE (mode);
698 CSELIB_VAL_PTR (e->u.val_rtx) = e;
701 e->next_containing_mem = 0;
705 /* ADDR_ELT is a value that is used as address. MEM_ELT is the value that
706 contains the data at this address. X is a MEM that represents the
707 value. Update the two value structures to represent this situation. */
710 add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x)
712 struct elt_loc_list *l;
714 /* Avoid duplicates. */
715 for (l = mem_elt->locs; l; l = l->next)
716 if (GET_CODE (l->loc) == MEM
717 && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt)
720 addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
722 = new_elt_loc_list (mem_elt->locs,
723 replace_equiv_address_nv (x, addr_elt->u.val_rtx));
724 if (mem_elt->next_containing_mem == NULL)
726 mem_elt->next_containing_mem = first_containing_mem;
727 first_containing_mem = mem_elt;
731 /* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx.
732 If CREATE, make a new one if we haven't seen it before. */
735 cselib_lookup_mem (rtx x, int create)
737 enum machine_mode mode = GET_MODE (x);
743 if (MEM_VOLATILE_P (x) || mode == BLKmode
744 || (FLOAT_MODE_P (mode) && flag_float_store))
747 /* Look up the value for the address. */
748 addr = cselib_lookup (XEXP (x, 0), mode, create);
752 /* Find a value that describes a value of our mode at that address. */
753 for (l = addr->addr_list; l; l = l->next)
754 if (GET_MODE (l->elt->u.val_rtx) == mode)
760 mem_elt = new_cselib_val (++next_unknown_value, mode);
761 add_mem_for_addr (addr, mem_elt, x);
762 slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
763 mem_elt->value, INSERT);
768 /* Walk rtx X and replace all occurrences of REG and MEM subexpressions
769 with VALUE expressions. This way, it becomes independent of changes
770 to registers and memory.
771 X isn't actually modified; if modifications are needed, new rtl is
772 allocated. However, the return value can share rtl with X. */
775 cselib_subst_to_values (rtx x)
777 enum rtx_code code = GET_CODE (x);
778 const char *fmt = GET_RTX_FORMAT (code);
787 l = REG_VALUES (REGNO (x));
788 if (l && l->elt == NULL)
790 for (; l; l = l->next)
791 if (GET_MODE (l->elt->u.val_rtx) == GET_MODE (x))
792 return l->elt->u.val_rtx;
797 e = cselib_lookup_mem (x, 0);
800 /* This happens for autoincrements. Assign a value that doesn't
802 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
817 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
824 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
828 rtx t = cselib_subst_to_values (XEXP (x, i));
830 if (t != XEXP (x, i) && x == copy)
831 copy = shallow_copy_rtx (x);
835 else if (fmt[i] == 'E')
839 for (j = 0; j < XVECLEN (x, i); j++)
841 rtx t = cselib_subst_to_values (XVECEXP (x, i, j));
843 if (t != XVECEXP (x, i, j) && XVEC (x, i) == XVEC (copy, i))
846 copy = shallow_copy_rtx (x);
848 XVEC (copy, i) = rtvec_alloc (XVECLEN (x, i));
849 for (k = 0; k < j; k++)
850 XVECEXP (copy, i, k) = XVECEXP (x, i, k);
853 XVECEXP (copy, i, j) = t;
861 /* Look up the rtl expression X in our tables and return the value it has.
862 If CREATE is zero, we return NULL if we don't know the value. Otherwise,
863 we create a new one if possible, using mode MODE if X doesn't have a mode
864 (i.e. because it's a constant). */
867 cselib_lookup (rtx x, enum machine_mode mode, int create)
871 unsigned int hashval;
873 if (GET_MODE (x) != VOIDmode)
876 if (GET_CODE (x) == VALUE)
877 return CSELIB_VAL_PTR (x);
879 if (GET_CODE (x) == REG)
882 unsigned int i = REGNO (x);
885 if (l && l->elt == NULL)
887 for (; l; l = l->next)
888 if (mode == GET_MODE (l->elt->u.val_rtx))
894 if (i < FIRST_PSEUDO_REGISTER)
896 unsigned int n = HARD_REGNO_NREGS (i, mode);
898 if (n > max_value_regs)
902 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
903 e->locs = new_elt_loc_list (e->locs, x);
904 if (REG_VALUES (i) == 0)
906 /* Maintain the invariant that the first entry of
907 REG_VALUES, if present, must be the value used to set the
908 register, or NULL. */
909 VARRAY_PUSH_UINT (used_regs, i);
910 REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL);
912 REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e);
913 slot = htab_find_slot_with_hash (hash_table, x, e->value, INSERT);
918 if (GET_CODE (x) == MEM)
919 return cselib_lookup_mem (x, create);
921 hashval = hash_rtx (x, mode, create);
922 /* Can't even create if hashing is not possible. */
926 slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
927 hashval, create ? INSERT : NO_INSERT);
931 e = (cselib_val *) *slot;
935 e = new_cselib_val (hashval, mode);
937 /* We have to fill the slot before calling cselib_subst_to_values:
938 the hash table is inconsistent until we do so, and
939 cselib_subst_to_values will need to do lookups. */
941 e->locs = new_elt_loc_list (e->locs, cselib_subst_to_values (x));
945 /* Invalidate any entries in reg_values that overlap REGNO. This is called
946 if REGNO is changing. MODE is the mode of the assignment to REGNO, which
947 is used to determine how many hard registers are being changed. If MODE
948 is VOIDmode, then only REGNO is being changed; this is used when
949 invalidating call clobbered registers across a call. */
952 cselib_invalidate_regno (unsigned int regno, enum machine_mode mode)
954 unsigned int endregno;
957 /* If we see pseudos after reload, something is _wrong_. */
958 if (reload_completed && regno >= FIRST_PSEUDO_REGISTER
959 && reg_renumber[regno] >= 0)
962 /* Determine the range of registers that must be invalidated. For
963 pseudos, only REGNO is affected. For hard regs, we must take MODE
964 into account, and we must also invalidate lower register numbers
965 if they contain values that overlap REGNO. */
966 if (regno < FIRST_PSEUDO_REGISTER)
968 if (mode == VOIDmode)
971 if (regno < max_value_regs)
974 i = regno - max_value_regs;
976 endregno = regno + HARD_REGNO_NREGS (regno, mode);
981 endregno = regno + 1;
984 for (; i < endregno; i++)
986 struct elt_list **l = ®_VALUES (i);
988 /* Go through all known values for this reg; if it overlaps the range
989 we're invalidating, remove the value. */
992 cselib_val *v = (*l)->elt;
993 struct elt_loc_list **p;
994 unsigned int this_last = i;
996 if (i < FIRST_PSEUDO_REGISTER && v != NULL)
997 this_last += HARD_REGNO_NREGS (i, GET_MODE (v->u.val_rtx)) - 1;
999 if (this_last < regno || v == NULL)
1005 /* We have an overlap. */
1006 if (*l == REG_VALUES (i))
1008 /* Maintain the invariant that the first entry of
1009 REG_VALUES, if present, must be the value used to set
1010 the register, or NULL. This is also nice because
1011 then we won't push the same regno onto user_regs
1017 unchain_one_elt_list (l);
1019 /* Now, we clear the mapping from value to reg. It must exist, so
1020 this code will crash intentionally if it doesn't. */
1021 for (p = &v->locs; ; p = &(*p)->next)
1025 if (GET_CODE (x) == REG && REGNO (x) == i)
1027 unchain_one_elt_loc_list (p);
1037 /* Return 1 if X has a value that can vary even between two
1038 executions of the program. 0 means X can be compared reliably
1039 against certain constants or near-constants. */
1042 cselib_rtx_varies_p (rtx x ATTRIBUTE_UNUSED, int from_alias ATTRIBUTE_UNUSED)
1044 /* We actually don't need to verify very hard. This is because
1045 if X has actually changed, we invalidate the memory anyway,
1046 so assume that all common memory addresses are
1051 /* Invalidate any locations in the table which are changed because of a
1052 store to MEM_RTX. If this is called because of a non-const call
1053 instruction, MEM_RTX is (mem:BLK const0_rtx). */
1056 cselib_invalidate_mem (rtx mem_rtx)
1058 cselib_val **vp, *v, *next;
1062 mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
1063 mem_rtx = canon_rtx (mem_rtx);
1065 vp = &first_containing_mem;
1066 for (v = *vp; v != &dummy_val; v = next)
1068 bool has_mem = false;
1069 struct elt_loc_list **p = &v->locs;
1070 int had_locs = v->locs != 0;
1075 rtx canon_x = (*p)->canon_loc;
1077 struct elt_list **mem_chain;
1079 /* MEMs may occur in locations only at the top level; below
1080 that every MEM or REG is substituted by its VALUE. */
1081 if (GET_CODE (x) != MEM)
1087 canon_x = (*p)->canon_loc = canon_rtx (x);
1088 if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
1089 && ! canon_true_dependence (mem_rtx, GET_MODE (mem_rtx), mem_addr,
1090 x, cselib_rtx_varies_p))
1098 /* This one overlaps. */
1099 /* We must have a mapping from this MEM's address to the
1100 value (E). Remove that, too. */
1101 addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0);
1102 mem_chain = &addr->addr_list;
1105 if ((*mem_chain)->elt == v)
1107 unchain_one_elt_list (mem_chain);
1111 mem_chain = &(*mem_chain)->next;
1114 unchain_one_elt_loc_list (p);
1117 if (had_locs && v->locs == 0)
1120 next = v->next_containing_mem;
1124 vp = &(*vp)->next_containing_mem;
1127 v->next_containing_mem = NULL;
1132 /* Invalidate DEST, which is being assigned to or clobbered. The second and
1133 the third parameter exist so that this function can be passed to
1134 note_stores; they are ignored. */
1137 cselib_invalidate_rtx (rtx dest, rtx ignore ATTRIBUTE_UNUSED,
1138 void *data ATTRIBUTE_UNUSED)
1140 while (GET_CODE (dest) == STRICT_LOW_PART || GET_CODE (dest) == SIGN_EXTRACT
1141 || GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SUBREG)
1142 dest = XEXP (dest, 0);
1144 if (GET_CODE (dest) == REG)
1145 cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
1146 else if (GET_CODE (dest) == MEM)
1147 cselib_invalidate_mem (dest);
1149 /* Some machines don't define AUTO_INC_DEC, but they still use push
1150 instructions. We need to catch that case here in order to
1151 invalidate the stack pointer correctly. Note that invalidating
1152 the stack pointer is different from invalidating DEST. */
1153 if (push_operand (dest, GET_MODE (dest)))
1154 cselib_invalidate_rtx (stack_pointer_rtx, NULL_RTX, NULL);
1157 /* Record the result of a SET instruction. DEST is being set; the source
1158 contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT
1159 describes its address. */
1162 cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
1164 int dreg = GET_CODE (dest) == REG ? (int) REGNO (dest) : -1;
1166 if (src_elt == 0 || side_effects_p (dest))
1171 if (dreg < FIRST_PSEUDO_REGISTER)
1173 unsigned int n = HARD_REGNO_NREGS (dreg, GET_MODE (dest));
1175 if (n > max_value_regs)
1179 if (REG_VALUES (dreg) == 0)
1181 VARRAY_PUSH_UINT (used_regs, dreg);
1182 REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
1186 if (REG_VALUES (dreg)->elt == 0)
1187 REG_VALUES (dreg)->elt = src_elt;
1189 /* The register should have been invalidated. */
1193 if (src_elt->locs == 0)
1195 src_elt->locs = new_elt_loc_list (src_elt->locs, dest);
1197 else if (GET_CODE (dest) == MEM && dest_addr_elt != 0)
1199 if (src_elt->locs == 0)
1201 add_mem_for_addr (dest_addr_elt, src_elt, dest);
1205 /* Describe a single set that is part of an insn. */
1210 cselib_val *src_elt;
1211 cselib_val *dest_addr_elt;
1214 /* There is no good way to determine how many elements there can be
1215 in a PARALLEL. Since it's fairly cheap, use a really large number. */
1216 #define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
1218 /* Record the effects of any sets in INSN. */
1220 cselib_record_sets (rtx insn)
1224 struct set sets[MAX_SETS];
1225 rtx body = PATTERN (insn);
1228 body = PATTERN (insn);
1229 if (GET_CODE (body) == COND_EXEC)
1231 cond = COND_EXEC_TEST (body);
1232 body = COND_EXEC_CODE (body);
1235 /* Find all sets. */
1236 if (GET_CODE (body) == SET)
1238 sets[0].src = SET_SRC (body);
1239 sets[0].dest = SET_DEST (body);
1242 else if (GET_CODE (body) == PARALLEL)
1244 /* Look through the PARALLEL and record the values being
1245 set, if possible. Also handle any CLOBBERs. */
1246 for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
1248 rtx x = XVECEXP (body, 0, i);
1250 if (GET_CODE (x) == SET)
1252 sets[n_sets].src = SET_SRC (x);
1253 sets[n_sets].dest = SET_DEST (x);
1259 /* Look up the values that are read. Do this before invalidating the
1260 locations that are written. */
1261 for (i = 0; i < n_sets; i++)
1263 rtx dest = sets[i].dest;
1265 /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
1266 the low part after invalidating any knowledge about larger modes. */
1267 if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
1268 sets[i].dest = dest = XEXP (dest, 0);
1270 /* We don't know how to record anything but REG or MEM. */
1271 if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1273 rtx src = sets[i].src;
1275 src = gen_rtx_IF_THEN_ELSE (GET_MODE (src), cond, src, dest);
1276 sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1);
1277 if (GET_CODE (dest) == MEM)
1278 sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0), Pmode, 1);
1280 sets[i].dest_addr_elt = 0;
1284 /* Invalidate all locations written by this insn. Note that the elts we
1285 looked up in the previous loop aren't affected, just some of their
1286 locations may go away. */
1287 note_stores (body, cselib_invalidate_rtx, NULL);
1289 /* Now enter the equivalences in our tables. */
1290 for (i = 0; i < n_sets; i++)
1292 rtx dest = sets[i].dest;
1293 if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1294 cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
1298 /* Record the effects of INSN. */
1301 cselib_process_insn (rtx insn)
1306 if (find_reg_note (insn, REG_LIBCALL, NULL))
1307 cselib_current_insn_in_libcall = true;
1308 if (find_reg_note (insn, REG_RETVAL, NULL))
1309 cselib_current_insn_in_libcall = false;
1310 cselib_current_insn = insn;
1312 /* Forget everything at a CODE_LABEL, a volatile asm, or a setjmp. */
1313 if (GET_CODE (insn) == CODE_LABEL
1314 || (GET_CODE (insn) == CALL_INSN
1315 && find_reg_note (insn, REG_SETJMP, NULL))
1316 || (GET_CODE (insn) == INSN
1317 && GET_CODE (PATTERN (insn)) == ASM_OPERANDS
1318 && MEM_VOLATILE_P (PATTERN (insn))))
1324 if (! INSN_P (insn))
1326 cselib_current_insn = 0;
1330 /* If this is a call instruction, forget anything stored in a
1331 call clobbered register, or, if this is not a const call, in
1333 if (GET_CODE (insn) == CALL_INSN)
1335 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1336 if (call_used_regs[i])
1337 cselib_invalidate_regno (i, reg_raw_mode[i]);
1339 if (! CONST_OR_PURE_CALL_P (insn))
1340 cselib_invalidate_mem (callmem);
1343 cselib_record_sets (insn);
1346 /* Clobber any registers which appear in REG_INC notes. We
1347 could keep track of the changes to their values, but it is
1348 unlikely to help. */
1349 for (x = REG_NOTES (insn); x; x = XEXP (x, 1))
1350 if (REG_NOTE_KIND (x) == REG_INC)
1351 cselib_invalidate_rtx (XEXP (x, 0), NULL_RTX, NULL);
1354 /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
1355 after we have processed the insn. */
1356 if (GET_CODE (insn) == CALL_INSN)
1357 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
1358 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
1359 cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0), NULL_RTX, NULL);
1361 cselib_current_insn = 0;
1363 if (n_useless_values > MAX_USELESS_VALUES)
1364 remove_useless_values ();
1367 /* Make sure our varrays are big enough. Not called from any cselib routines;
1368 it must be called by the user if it allocated new registers. */
1371 cselib_update_varray_sizes (void)
1373 unsigned int nregs = max_reg_num ();
1375 if (nregs == cselib_nregs)
1378 cselib_nregs = nregs;
1379 VARRAY_GROW (reg_values, nregs);
1380 VARRAY_GROW (used_regs, nregs);
1383 /* Initialize cselib for one pass. The caller must also call
1384 init_alias_analysis. */
1389 elt_list_pool = create_alloc_pool ("elt_list",
1390 sizeof (struct elt_list), 10);
1391 elt_loc_list_pool = create_alloc_pool ("elt_loc_list",
1392 sizeof (struct elt_loc_list), 10);
1393 cselib_val_pool = create_alloc_pool ("cselib_val_list",
1394 sizeof (cselib_val), 10);
1395 /* This is only created once. */
1397 callmem = gen_rtx_MEM (BLKmode, const0_rtx);
1399 cselib_nregs = max_reg_num ();
1400 if (reg_values_old != NULL && VARRAY_SIZE (reg_values_old) >= cselib_nregs)
1402 reg_values = reg_values_old;
1403 used_regs = used_regs_old;
1407 VARRAY_ELT_LIST_INIT (reg_values, cselib_nregs, "reg_values");
1408 VARRAY_UINT_INIT (used_regs, cselib_nregs, "used_regs");
1410 hash_table = htab_create_ggc (31, get_value_hash, entry_and_rtx_equal_p,
1412 cselib_current_insn_in_libcall = false;
1415 /* Called when the current user is done with cselib. */
1418 cselib_finish (void)
1420 free_alloc_pool (elt_list_pool);
1421 free_alloc_pool (elt_loc_list_pool);
1422 free_alloc_pool (cselib_val_pool);
1424 reg_values_old = reg_values;
1426 used_regs_old = used_regs;
1429 n_useless_values = 0;
1430 next_unknown_value = 0;
1433 #include "gt-cselib.h"