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, value_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 /* We use custom method to allocate this RTL construct because it accounts
698 about 8% of overall memory usage. */
699 e->u.val_rtx = pool_alloc (value_pool);
700 memset (e->u.val_rtx, 0, RTX_HDR_SIZE);
701 PUT_CODE (e->u.val_rtx, VALUE);
702 PUT_MODE (e->u.val_rtx, mode);
703 CSELIB_VAL_PTR (e->u.val_rtx) = e;
706 e->next_containing_mem = 0;
710 /* ADDR_ELT is a value that is used as address. MEM_ELT is the value that
711 contains the data at this address. X is a MEM that represents the
712 value. Update the two value structures to represent this situation. */
715 add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x)
717 struct elt_loc_list *l;
719 /* Avoid duplicates. */
720 for (l = mem_elt->locs; l; l = l->next)
721 if (GET_CODE (l->loc) == MEM
722 && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt)
725 addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
727 = new_elt_loc_list (mem_elt->locs,
728 replace_equiv_address_nv (x, addr_elt->u.val_rtx));
729 if (mem_elt->next_containing_mem == NULL)
731 mem_elt->next_containing_mem = first_containing_mem;
732 first_containing_mem = mem_elt;
736 /* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx.
737 If CREATE, make a new one if we haven't seen it before. */
740 cselib_lookup_mem (rtx x, int create)
742 enum machine_mode mode = GET_MODE (x);
748 if (MEM_VOLATILE_P (x) || mode == BLKmode
749 || (FLOAT_MODE_P (mode) && flag_float_store))
752 /* Look up the value for the address. */
753 addr = cselib_lookup (XEXP (x, 0), mode, create);
757 /* Find a value that describes a value of our mode at that address. */
758 for (l = addr->addr_list; l; l = l->next)
759 if (GET_MODE (l->elt->u.val_rtx) == mode)
765 mem_elt = new_cselib_val (++next_unknown_value, mode);
766 add_mem_for_addr (addr, mem_elt, x);
767 slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
768 mem_elt->value, INSERT);
773 /* Walk rtx X and replace all occurrences of REG and MEM subexpressions
774 with VALUE expressions. This way, it becomes independent of changes
775 to registers and memory.
776 X isn't actually modified; if modifications are needed, new rtl is
777 allocated. However, the return value can share rtl with X. */
780 cselib_subst_to_values (rtx x)
782 enum rtx_code code = GET_CODE (x);
783 const char *fmt = GET_RTX_FORMAT (code);
792 l = REG_VALUES (REGNO (x));
793 if (l && l->elt == NULL)
795 for (; l; l = l->next)
796 if (GET_MODE (l->elt->u.val_rtx) == GET_MODE (x))
797 return l->elt->u.val_rtx;
802 e = cselib_lookup_mem (x, 0);
805 /* This happens for autoincrements. Assign a value that doesn't
807 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
822 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
829 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
833 rtx t = cselib_subst_to_values (XEXP (x, i));
835 if (t != XEXP (x, i) && x == copy)
836 copy = shallow_copy_rtx (x);
840 else if (fmt[i] == 'E')
844 for (j = 0; j < XVECLEN (x, i); j++)
846 rtx t = cselib_subst_to_values (XVECEXP (x, i, j));
848 if (t != XVECEXP (x, i, j) && XVEC (x, i) == XVEC (copy, i))
851 copy = shallow_copy_rtx (x);
853 XVEC (copy, i) = rtvec_alloc (XVECLEN (x, i));
854 for (k = 0; k < j; k++)
855 XVECEXP (copy, i, k) = XVECEXP (x, i, k);
858 XVECEXP (copy, i, j) = t;
866 /* Look up the rtl expression X in our tables and return the value it has.
867 If CREATE is zero, we return NULL if we don't know the value. Otherwise,
868 we create a new one if possible, using mode MODE if X doesn't have a mode
869 (i.e. because it's a constant). */
872 cselib_lookup (rtx x, enum machine_mode mode, int create)
876 unsigned int hashval;
878 if (GET_MODE (x) != VOIDmode)
881 if (GET_CODE (x) == VALUE)
882 return CSELIB_VAL_PTR (x);
884 if (GET_CODE (x) == REG)
887 unsigned int i = REGNO (x);
890 if (l && l->elt == NULL)
892 for (; l; l = l->next)
893 if (mode == GET_MODE (l->elt->u.val_rtx))
899 if (i < FIRST_PSEUDO_REGISTER)
901 unsigned int n = HARD_REGNO_NREGS (i, mode);
903 if (n > max_value_regs)
907 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
908 e->locs = new_elt_loc_list (e->locs, x);
909 if (REG_VALUES (i) == 0)
911 /* Maintain the invariant that the first entry of
912 REG_VALUES, if present, must be the value used to set the
913 register, or NULL. */
914 VARRAY_PUSH_UINT (used_regs, i);
915 REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL);
917 REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e);
918 slot = htab_find_slot_with_hash (hash_table, x, e->value, INSERT);
923 if (GET_CODE (x) == MEM)
924 return cselib_lookup_mem (x, create);
926 hashval = hash_rtx (x, mode, create);
927 /* Can't even create if hashing is not possible. */
931 slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
932 hashval, create ? INSERT : NO_INSERT);
936 e = (cselib_val *) *slot;
940 e = new_cselib_val (hashval, mode);
942 /* We have to fill the slot before calling cselib_subst_to_values:
943 the hash table is inconsistent until we do so, and
944 cselib_subst_to_values will need to do lookups. */
946 e->locs = new_elt_loc_list (e->locs, cselib_subst_to_values (x));
950 /* Invalidate any entries in reg_values that overlap REGNO. This is called
951 if REGNO is changing. MODE is the mode of the assignment to REGNO, which
952 is used to determine how many hard registers are being changed. If MODE
953 is VOIDmode, then only REGNO is being changed; this is used when
954 invalidating call clobbered registers across a call. */
957 cselib_invalidate_regno (unsigned int regno, enum machine_mode mode)
959 unsigned int endregno;
962 /* If we see pseudos after reload, something is _wrong_. */
963 if (reload_completed && regno >= FIRST_PSEUDO_REGISTER
964 && reg_renumber[regno] >= 0)
967 /* Determine the range of registers that must be invalidated. For
968 pseudos, only REGNO is affected. For hard regs, we must take MODE
969 into account, and we must also invalidate lower register numbers
970 if they contain values that overlap REGNO. */
971 if (regno < FIRST_PSEUDO_REGISTER)
973 if (mode == VOIDmode)
976 if (regno < max_value_regs)
979 i = regno - max_value_regs;
981 endregno = regno + HARD_REGNO_NREGS (regno, mode);
986 endregno = regno + 1;
989 for (; i < endregno; i++)
991 struct elt_list **l = ®_VALUES (i);
993 /* Go through all known values for this reg; if it overlaps the range
994 we're invalidating, remove the value. */
997 cselib_val *v = (*l)->elt;
998 struct elt_loc_list **p;
999 unsigned int this_last = i;
1001 if (i < FIRST_PSEUDO_REGISTER && v != NULL)
1002 this_last += HARD_REGNO_NREGS (i, GET_MODE (v->u.val_rtx)) - 1;
1004 if (this_last < regno || v == NULL)
1010 /* We have an overlap. */
1011 if (*l == REG_VALUES (i))
1013 /* Maintain the invariant that the first entry of
1014 REG_VALUES, if present, must be the value used to set
1015 the register, or NULL. This is also nice because
1016 then we won't push the same regno onto user_regs
1022 unchain_one_elt_list (l);
1024 /* Now, we clear the mapping from value to reg. It must exist, so
1025 this code will crash intentionally if it doesn't. */
1026 for (p = &v->locs; ; p = &(*p)->next)
1030 if (GET_CODE (x) == REG && REGNO (x) == i)
1032 unchain_one_elt_loc_list (p);
1042 /* Return 1 if X has a value that can vary even between two
1043 executions of the program. 0 means X can be compared reliably
1044 against certain constants or near-constants. */
1047 cselib_rtx_varies_p (rtx x ATTRIBUTE_UNUSED, int from_alias ATTRIBUTE_UNUSED)
1049 /* We actually don't need to verify very hard. This is because
1050 if X has actually changed, we invalidate the memory anyway,
1051 so assume that all common memory addresses are
1056 /* Invalidate any locations in the table which are changed because of a
1057 store to MEM_RTX. If this is called because of a non-const call
1058 instruction, MEM_RTX is (mem:BLK const0_rtx). */
1061 cselib_invalidate_mem (rtx mem_rtx)
1063 cselib_val **vp, *v, *next;
1067 mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
1068 mem_rtx = canon_rtx (mem_rtx);
1070 vp = &first_containing_mem;
1071 for (v = *vp; v != &dummy_val; v = next)
1073 bool has_mem = false;
1074 struct elt_loc_list **p = &v->locs;
1075 int had_locs = v->locs != 0;
1080 rtx canon_x = (*p)->canon_loc;
1082 struct elt_list **mem_chain;
1084 /* MEMs may occur in locations only at the top level; below
1085 that every MEM or REG is substituted by its VALUE. */
1086 if (GET_CODE (x) != MEM)
1092 canon_x = (*p)->canon_loc = canon_rtx (x);
1093 if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
1094 && ! canon_true_dependence (mem_rtx, GET_MODE (mem_rtx), mem_addr,
1095 x, cselib_rtx_varies_p))
1103 /* This one overlaps. */
1104 /* We must have a mapping from this MEM's address to the
1105 value (E). Remove that, too. */
1106 addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0);
1107 mem_chain = &addr->addr_list;
1110 if ((*mem_chain)->elt == v)
1112 unchain_one_elt_list (mem_chain);
1116 mem_chain = &(*mem_chain)->next;
1119 unchain_one_elt_loc_list (p);
1122 if (had_locs && v->locs == 0)
1125 next = v->next_containing_mem;
1129 vp = &(*vp)->next_containing_mem;
1132 v->next_containing_mem = NULL;
1137 /* Invalidate DEST, which is being assigned to or clobbered. The second and
1138 the third parameter exist so that this function can be passed to
1139 note_stores; they are ignored. */
1142 cselib_invalidate_rtx (rtx dest, rtx ignore ATTRIBUTE_UNUSED,
1143 void *data ATTRIBUTE_UNUSED)
1145 while (GET_CODE (dest) == STRICT_LOW_PART || GET_CODE (dest) == SIGN_EXTRACT
1146 || GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SUBREG)
1147 dest = XEXP (dest, 0);
1149 if (GET_CODE (dest) == REG)
1150 cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
1151 else if (GET_CODE (dest) == MEM)
1152 cselib_invalidate_mem (dest);
1154 /* Some machines don't define AUTO_INC_DEC, but they still use push
1155 instructions. We need to catch that case here in order to
1156 invalidate the stack pointer correctly. Note that invalidating
1157 the stack pointer is different from invalidating DEST. */
1158 if (push_operand (dest, GET_MODE (dest)))
1159 cselib_invalidate_rtx (stack_pointer_rtx, NULL_RTX, NULL);
1162 /* Record the result of a SET instruction. DEST is being set; the source
1163 contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT
1164 describes its address. */
1167 cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
1169 int dreg = GET_CODE (dest) == REG ? (int) REGNO (dest) : -1;
1171 if (src_elt == 0 || side_effects_p (dest))
1176 if (dreg < FIRST_PSEUDO_REGISTER)
1178 unsigned int n = HARD_REGNO_NREGS (dreg, GET_MODE (dest));
1180 if (n > max_value_regs)
1184 if (REG_VALUES (dreg) == 0)
1186 VARRAY_PUSH_UINT (used_regs, dreg);
1187 REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
1191 if (REG_VALUES (dreg)->elt == 0)
1192 REG_VALUES (dreg)->elt = src_elt;
1194 /* The register should have been invalidated. */
1198 if (src_elt->locs == 0)
1200 src_elt->locs = new_elt_loc_list (src_elt->locs, dest);
1202 else if (GET_CODE (dest) == MEM && dest_addr_elt != 0)
1204 if (src_elt->locs == 0)
1206 add_mem_for_addr (dest_addr_elt, src_elt, dest);
1210 /* Describe a single set that is part of an insn. */
1215 cselib_val *src_elt;
1216 cselib_val *dest_addr_elt;
1219 /* There is no good way to determine how many elements there can be
1220 in a PARALLEL. Since it's fairly cheap, use a really large number. */
1221 #define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
1223 /* Record the effects of any sets in INSN. */
1225 cselib_record_sets (rtx insn)
1229 struct set sets[MAX_SETS];
1230 rtx body = PATTERN (insn);
1233 body = PATTERN (insn);
1234 if (GET_CODE (body) == COND_EXEC)
1236 cond = COND_EXEC_TEST (body);
1237 body = COND_EXEC_CODE (body);
1240 /* Find all sets. */
1241 if (GET_CODE (body) == SET)
1243 sets[0].src = SET_SRC (body);
1244 sets[0].dest = SET_DEST (body);
1247 else if (GET_CODE (body) == PARALLEL)
1249 /* Look through the PARALLEL and record the values being
1250 set, if possible. Also handle any CLOBBERs. */
1251 for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
1253 rtx x = XVECEXP (body, 0, i);
1255 if (GET_CODE (x) == SET)
1257 sets[n_sets].src = SET_SRC (x);
1258 sets[n_sets].dest = SET_DEST (x);
1264 /* Look up the values that are read. Do this before invalidating the
1265 locations that are written. */
1266 for (i = 0; i < n_sets; i++)
1268 rtx dest = sets[i].dest;
1270 /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
1271 the low part after invalidating any knowledge about larger modes. */
1272 if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
1273 sets[i].dest = dest = XEXP (dest, 0);
1275 /* We don't know how to record anything but REG or MEM. */
1276 if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1278 rtx src = sets[i].src;
1280 src = gen_rtx_IF_THEN_ELSE (GET_MODE (src), cond, src, dest);
1281 sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1);
1282 if (GET_CODE (dest) == MEM)
1283 sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0), Pmode, 1);
1285 sets[i].dest_addr_elt = 0;
1289 /* Invalidate all locations written by this insn. Note that the elts we
1290 looked up in the previous loop aren't affected, just some of their
1291 locations may go away. */
1292 note_stores (body, cselib_invalidate_rtx, NULL);
1294 /* Now enter the equivalences in our tables. */
1295 for (i = 0; i < n_sets; i++)
1297 rtx dest = sets[i].dest;
1298 if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1299 cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
1303 /* Record the effects of INSN. */
1306 cselib_process_insn (rtx insn)
1311 if (find_reg_note (insn, REG_LIBCALL, NULL))
1312 cselib_current_insn_in_libcall = true;
1313 if (find_reg_note (insn, REG_RETVAL, NULL))
1314 cselib_current_insn_in_libcall = false;
1315 cselib_current_insn = insn;
1317 /* Forget everything at a CODE_LABEL, a volatile asm, or a setjmp. */
1318 if (GET_CODE (insn) == CODE_LABEL
1319 || (GET_CODE (insn) == CALL_INSN
1320 && find_reg_note (insn, REG_SETJMP, NULL))
1321 || (GET_CODE (insn) == INSN
1322 && GET_CODE (PATTERN (insn)) == ASM_OPERANDS
1323 && MEM_VOLATILE_P (PATTERN (insn))))
1329 if (! INSN_P (insn))
1331 cselib_current_insn = 0;
1335 /* If this is a call instruction, forget anything stored in a
1336 call clobbered register, or, if this is not a const call, in
1338 if (GET_CODE (insn) == CALL_INSN)
1340 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1341 if (call_used_regs[i])
1342 cselib_invalidate_regno (i, reg_raw_mode[i]);
1344 if (! CONST_OR_PURE_CALL_P (insn))
1345 cselib_invalidate_mem (callmem);
1348 cselib_record_sets (insn);
1351 /* Clobber any registers which appear in REG_INC notes. We
1352 could keep track of the changes to their values, but it is
1353 unlikely to help. */
1354 for (x = REG_NOTES (insn); x; x = XEXP (x, 1))
1355 if (REG_NOTE_KIND (x) == REG_INC)
1356 cselib_invalidate_rtx (XEXP (x, 0), NULL_RTX, NULL);
1359 /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
1360 after we have processed the insn. */
1361 if (GET_CODE (insn) == CALL_INSN)
1362 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
1363 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
1364 cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0), NULL_RTX, NULL);
1366 cselib_current_insn = 0;
1368 if (n_useless_values > MAX_USELESS_VALUES)
1369 remove_useless_values ();
1372 /* Make sure our varrays are big enough. Not called from any cselib routines;
1373 it must be called by the user if it allocated new registers. */
1376 cselib_update_varray_sizes (void)
1378 unsigned int nregs = max_reg_num ();
1380 if (nregs == cselib_nregs)
1383 cselib_nregs = nregs;
1384 VARRAY_GROW (reg_values, nregs);
1385 VARRAY_GROW (used_regs, nregs);
1388 /* Initialize cselib for one pass. The caller must also call
1389 init_alias_analysis. */
1394 elt_list_pool = create_alloc_pool ("elt_list",
1395 sizeof (struct elt_list), 10);
1396 elt_loc_list_pool = create_alloc_pool ("elt_loc_list",
1397 sizeof (struct elt_loc_list), 10);
1398 cselib_val_pool = create_alloc_pool ("cselib_val_list",
1399 sizeof (cselib_val), 10);
1400 value_pool = create_alloc_pool ("value",
1401 RTX_SIZE (VALUE), 100);
1402 /* This is only created once. */
1404 callmem = gen_rtx_MEM (BLKmode, const0_rtx);
1406 cselib_nregs = max_reg_num ();
1407 if (reg_values_old != NULL && VARRAY_SIZE (reg_values_old) >= cselib_nregs)
1409 reg_values = reg_values_old;
1410 used_regs = used_regs_old;
1414 VARRAY_ELT_LIST_INIT (reg_values, cselib_nregs, "reg_values");
1415 VARRAY_UINT_INIT (used_regs, cselib_nregs, "used_regs");
1417 hash_table = htab_create_ggc (31, get_value_hash, entry_and_rtx_equal_p,
1419 cselib_current_insn_in_libcall = false;
1422 /* Called when the current user is done with cselib. */
1425 cselib_finish (void)
1427 free_alloc_pool (elt_list_pool);
1428 free_alloc_pool (elt_loc_list_pool);
1429 free_alloc_pool (cselib_val_pool);
1430 free_alloc_pool (value_pool);
1432 reg_values_old = reg_values;
1434 used_regs_old = used_regs;
1437 n_useless_values = 0;
1438 next_unknown_value = 0;
1441 #include "gt-cselib.h"