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 CSELIB_VAL_PTR (v->u.val_rtx) = NULL;
336 htab_clear_slot (hash_table, x);
337 unchain_one_value (v);
344 /* Clean out useless values (i.e. those which no longer have locations
345 associated with them) from the hash table. */
348 remove_useless_values (void)
351 /* First pass: eliminate locations that reference the value. That in
352 turn can make more values useless. */
355 values_became_useless = 0;
356 htab_traverse (hash_table, discard_useless_locs, 0);
358 while (values_became_useless);
360 /* Second pass: actually remove the values. */
361 p = &first_containing_mem;
362 for (v = *p; v != &dummy_val; v = v->next_containing_mem)
366 p = &(*p)->next_containing_mem;
370 htab_traverse (hash_table, discard_useless_values, 0);
372 if (n_useless_values != 0)
376 /* Return the mode in which a register was last set. If X is not a
377 register, return its mode. If the mode in which the register was
378 set is not known, or the value was already clobbered, return
382 cselib_reg_set_mode (rtx x)
384 if (GET_CODE (x) != REG)
387 if (REG_VALUES (REGNO (x)) == NULL
388 || REG_VALUES (REGNO (x))->elt == NULL)
391 return GET_MODE (REG_VALUES (REGNO (x))->elt->u.val_rtx);
394 /* Return nonzero if we can prove that X and Y contain the same value, taking
395 our gathered information into account. */
398 rtx_equal_for_cselib_p (rtx x, rtx y)
404 if (GET_CODE (x) == REG || GET_CODE (x) == MEM)
406 cselib_val *e = cselib_lookup (x, GET_MODE (x), 0);
412 if (GET_CODE (y) == REG || GET_CODE (y) == MEM)
414 cselib_val *e = cselib_lookup (y, GET_MODE (y), 0);
423 if (GET_CODE (x) == VALUE && GET_CODE (y) == VALUE)
424 return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y);
426 if (GET_CODE (x) == VALUE)
428 cselib_val *e = CSELIB_VAL_PTR (x);
429 struct elt_loc_list *l;
431 for (l = e->locs; l; l = l->next)
435 /* Avoid infinite recursion. */
436 if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
438 else if (rtx_equal_for_cselib_p (t, y))
445 if (GET_CODE (y) == VALUE)
447 cselib_val *e = CSELIB_VAL_PTR (y);
448 struct elt_loc_list *l;
450 for (l = e->locs; l; l = l->next)
454 if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
456 else if (rtx_equal_for_cselib_p (x, t))
463 if (GET_CODE (x) != GET_CODE (y) || GET_MODE (x) != GET_MODE (y))
466 /* This won't be handled correctly by the code below. */
467 if (GET_CODE (x) == LABEL_REF)
468 return XEXP (x, 0) == XEXP (y, 0);
471 fmt = GET_RTX_FORMAT (code);
473 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
480 if (XWINT (x, i) != XWINT (y, i))
486 if (XINT (x, i) != XINT (y, i))
492 /* Two vectors must have the same length. */
493 if (XVECLEN (x, i) != XVECLEN (y, i))
496 /* And the corresponding elements must match. */
497 for (j = 0; j < XVECLEN (x, i); j++)
498 if (! rtx_equal_for_cselib_p (XVECEXP (x, i, j),
504 if (! rtx_equal_for_cselib_p (XEXP (x, i), XEXP (y, i)))
510 if (strcmp (XSTR (x, i), XSTR (y, i)))
515 /* These are just backpointers, so they don't matter. */
522 /* It is believed that rtx's at this level will never
523 contain anything but integers and other rtx's,
524 except for within LABEL_REFs and SYMBOL_REFs. */
532 /* We need to pass down the mode of constants through the hash table
533 functions. For that purpose, wrap them in a CONST of the appropriate
536 wrap_constant (enum machine_mode mode, rtx x)
538 if (GET_CODE (x) != CONST_INT
539 && (GET_CODE (x) != CONST_DOUBLE || GET_MODE (x) != VOIDmode))
541 if (mode == VOIDmode)
543 return gen_rtx_CONST (mode, x);
546 /* Hash an rtx. Return 0 if we couldn't hash the rtx.
547 For registers and memory locations, we look up their cselib_val structure
548 and return its VALUE element.
549 Possible reasons for return 0 are: the object is volatile, or we couldn't
550 find a register or memory location in the table and CREATE is zero. If
551 CREATE is nonzero, table elts are created for regs and mem.
552 MODE is used in hashing for CONST_INTs only;
553 otherwise the mode of X is used. */
556 hash_rtx (rtx x, enum machine_mode mode, int create)
562 unsigned int hash = 0;
565 hash += (unsigned) code + (unsigned) GET_MODE (x);
571 e = cselib_lookup (x, GET_MODE (x), create);
578 hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + INTVAL (x);
579 return hash ? hash : (unsigned int) CONST_INT;
582 /* This is like the general case, except that it only counts
583 the integers representing the constant. */
584 hash += (unsigned) code + (unsigned) GET_MODE (x);
585 if (GET_MODE (x) != VOIDmode)
586 hash += real_hash (CONST_DOUBLE_REAL_VALUE (x));
588 hash += ((unsigned) CONST_DOUBLE_LOW (x)
589 + (unsigned) CONST_DOUBLE_HIGH (x));
590 return hash ? hash : (unsigned int) CONST_DOUBLE;
597 units = CONST_VECTOR_NUNITS (x);
599 for (i = 0; i < units; ++i)
601 elt = CONST_VECTOR_ELT (x, i);
602 hash += hash_rtx (elt, GET_MODE (elt), 0);
608 /* Assume there is only one rtx object for any given label. */
611 += ((unsigned) LABEL_REF << 7) + (unsigned long) XEXP (x, 0);
612 return hash ? hash : (unsigned int) LABEL_REF;
616 += ((unsigned) SYMBOL_REF << 7) + (unsigned long) XSTR (x, 0);
617 return hash ? hash : (unsigned int) SYMBOL_REF;
628 case UNSPEC_VOLATILE:
632 if (MEM_VOLATILE_P (x))
641 i = GET_RTX_LENGTH (code) - 1;
642 fmt = GET_RTX_FORMAT (code);
647 rtx tem = XEXP (x, i);
648 unsigned int tem_hash = hash_rtx (tem, 0, create);
655 else if (fmt[i] == 'E')
656 for (j = 0; j < XVECLEN (x, i); j++)
658 unsigned int tem_hash = hash_rtx (XVECEXP (x, i, j), 0, create);
665 else if (fmt[i] == 's')
667 const unsigned char *p = (const unsigned char *) XSTR (x, i);
673 else if (fmt[i] == 'i')
675 else if (fmt[i] == '0' || fmt[i] == 't')
681 return hash ? hash : 1 + (unsigned int) GET_CODE (x);
684 /* Create a new value structure for VALUE and initialize it. The mode of the
687 static inline cselib_val *
688 new_cselib_val (unsigned int value, enum machine_mode mode)
690 cselib_val *e = pool_alloc (cselib_val_pool);
692 #ifdef ENABLE_CHECKING
698 /* We use custom method to allocate this RTL construct because it accounts
699 about 8% of overall memory usage. */
700 e->u.val_rtx = pool_alloc (value_pool);
701 memset (e->u.val_rtx, 0, RTX_HDR_SIZE);
702 PUT_CODE (e->u.val_rtx, VALUE);
703 PUT_MODE (e->u.val_rtx, mode);
704 CSELIB_VAL_PTR (e->u.val_rtx) = e;
707 e->next_containing_mem = 0;
711 /* ADDR_ELT is a value that is used as address. MEM_ELT is the value that
712 contains the data at this address. X is a MEM that represents the
713 value. Update the two value structures to represent this situation. */
716 add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x)
718 struct elt_loc_list *l;
720 /* Avoid duplicates. */
721 for (l = mem_elt->locs; l; l = l->next)
722 if (GET_CODE (l->loc) == MEM
723 && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt)
726 addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
728 = new_elt_loc_list (mem_elt->locs,
729 replace_equiv_address_nv (x, addr_elt->u.val_rtx));
730 if (mem_elt->next_containing_mem == NULL)
732 mem_elt->next_containing_mem = first_containing_mem;
733 first_containing_mem = mem_elt;
737 /* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx.
738 If CREATE, make a new one if we haven't seen it before. */
741 cselib_lookup_mem (rtx x, int create)
743 enum machine_mode mode = GET_MODE (x);
749 if (MEM_VOLATILE_P (x) || mode == BLKmode
750 || (FLOAT_MODE_P (mode) && flag_float_store))
753 /* Look up the value for the address. */
754 addr = cselib_lookup (XEXP (x, 0), mode, create);
758 /* Find a value that describes a value of our mode at that address. */
759 for (l = addr->addr_list; l; l = l->next)
760 if (GET_MODE (l->elt->u.val_rtx) == mode)
766 mem_elt = new_cselib_val (++next_unknown_value, mode);
767 add_mem_for_addr (addr, mem_elt, x);
768 slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
769 mem_elt->value, INSERT);
774 /* Walk rtx X and replace all occurrences of REG and MEM subexpressions
775 with VALUE expressions. This way, it becomes independent of changes
776 to registers and memory.
777 X isn't actually modified; if modifications are needed, new rtl is
778 allocated. However, the return value can share rtl with X. */
781 cselib_subst_to_values (rtx x)
783 enum rtx_code code = GET_CODE (x);
784 const char *fmt = GET_RTX_FORMAT (code);
793 l = REG_VALUES (REGNO (x));
794 if (l && l->elt == NULL)
796 for (; l; l = l->next)
797 if (GET_MODE (l->elt->u.val_rtx) == GET_MODE (x))
798 return l->elt->u.val_rtx;
803 e = cselib_lookup_mem (x, 0);
806 /* This happens for autoincrements. Assign a value that doesn't
808 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
823 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
830 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
834 rtx t = cselib_subst_to_values (XEXP (x, i));
836 if (t != XEXP (x, i) && x == copy)
837 copy = shallow_copy_rtx (x);
841 else if (fmt[i] == 'E')
845 for (j = 0; j < XVECLEN (x, i); j++)
847 rtx t = cselib_subst_to_values (XVECEXP (x, i, j));
849 if (t != XVECEXP (x, i, j) && XVEC (x, i) == XVEC (copy, i))
852 copy = shallow_copy_rtx (x);
854 XVEC (copy, i) = rtvec_alloc (XVECLEN (x, i));
855 for (k = 0; k < j; k++)
856 XVECEXP (copy, i, k) = XVECEXP (x, i, k);
859 XVECEXP (copy, i, j) = t;
867 /* Look up the rtl expression X in our tables and return the value it has.
868 If CREATE is zero, we return NULL if we don't know the value. Otherwise,
869 we create a new one if possible, using mode MODE if X doesn't have a mode
870 (i.e. because it's a constant). */
873 cselib_lookup (rtx x, enum machine_mode mode, int create)
877 unsigned int hashval;
879 if (GET_MODE (x) != VOIDmode)
882 if (GET_CODE (x) == VALUE)
883 return CSELIB_VAL_PTR (x);
885 if (GET_CODE (x) == REG)
888 unsigned int i = REGNO (x);
891 if (l && l->elt == NULL)
893 for (; l; l = l->next)
894 if (mode == GET_MODE (l->elt->u.val_rtx))
900 if (i < FIRST_PSEUDO_REGISTER)
902 unsigned int n = HARD_REGNO_NREGS (i, mode);
904 if (n > max_value_regs)
908 e = new_cselib_val (++next_unknown_value, GET_MODE (x));
909 e->locs = new_elt_loc_list (e->locs, x);
910 if (REG_VALUES (i) == 0)
912 /* Maintain the invariant that the first entry of
913 REG_VALUES, if present, must be the value used to set the
914 register, or NULL. */
915 VARRAY_PUSH_UINT (used_regs, i);
916 REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL);
918 REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e);
919 slot = htab_find_slot_with_hash (hash_table, x, e->value, INSERT);
924 if (GET_CODE (x) == MEM)
925 return cselib_lookup_mem (x, create);
927 hashval = hash_rtx (x, mode, create);
928 /* Can't even create if hashing is not possible. */
932 slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
933 hashval, create ? INSERT : NO_INSERT);
937 e = (cselib_val *) *slot;
941 e = new_cselib_val (hashval, mode);
943 /* We have to fill the slot before calling cselib_subst_to_values:
944 the hash table is inconsistent until we do so, and
945 cselib_subst_to_values will need to do lookups. */
947 e->locs = new_elt_loc_list (e->locs, cselib_subst_to_values (x));
951 /* Invalidate any entries in reg_values that overlap REGNO. This is called
952 if REGNO is changing. MODE is the mode of the assignment to REGNO, which
953 is used to determine how many hard registers are being changed. If MODE
954 is VOIDmode, then only REGNO is being changed; this is used when
955 invalidating call clobbered registers across a call. */
958 cselib_invalidate_regno (unsigned int regno, enum machine_mode mode)
960 unsigned int endregno;
963 /* If we see pseudos after reload, something is _wrong_. */
964 if (reload_completed && regno >= FIRST_PSEUDO_REGISTER
965 && reg_renumber[regno] >= 0)
968 /* Determine the range of registers that must be invalidated. For
969 pseudos, only REGNO is affected. For hard regs, we must take MODE
970 into account, and we must also invalidate lower register numbers
971 if they contain values that overlap REGNO. */
972 if (regno < FIRST_PSEUDO_REGISTER)
974 if (mode == VOIDmode)
977 if (regno < max_value_regs)
980 i = regno - max_value_regs;
982 endregno = regno + HARD_REGNO_NREGS (regno, mode);
987 endregno = regno + 1;
990 for (; i < endregno; i++)
992 struct elt_list **l = ®_VALUES (i);
994 /* Go through all known values for this reg; if it overlaps the range
995 we're invalidating, remove the value. */
998 cselib_val *v = (*l)->elt;
999 struct elt_loc_list **p;
1000 unsigned int this_last = i;
1002 if (i < FIRST_PSEUDO_REGISTER && v != NULL)
1003 this_last += HARD_REGNO_NREGS (i, GET_MODE (v->u.val_rtx)) - 1;
1005 if (this_last < regno || v == NULL)
1011 /* We have an overlap. */
1012 if (*l == REG_VALUES (i))
1014 /* Maintain the invariant that the first entry of
1015 REG_VALUES, if present, must be the value used to set
1016 the register, or NULL. This is also nice because
1017 then we won't push the same regno onto user_regs
1023 unchain_one_elt_list (l);
1025 /* Now, we clear the mapping from value to reg. It must exist, so
1026 this code will crash intentionally if it doesn't. */
1027 for (p = &v->locs; ; p = &(*p)->next)
1031 if (GET_CODE (x) == REG && REGNO (x) == i)
1033 unchain_one_elt_loc_list (p);
1043 /* Return 1 if X has a value that can vary even between two
1044 executions of the program. 0 means X can be compared reliably
1045 against certain constants or near-constants. */
1048 cselib_rtx_varies_p (rtx x ATTRIBUTE_UNUSED, int from_alias ATTRIBUTE_UNUSED)
1050 /* We actually don't need to verify very hard. This is because
1051 if X has actually changed, we invalidate the memory anyway,
1052 so assume that all common memory addresses are
1057 /* Invalidate any locations in the table which are changed because of a
1058 store to MEM_RTX. If this is called because of a non-const call
1059 instruction, MEM_RTX is (mem:BLK const0_rtx). */
1062 cselib_invalidate_mem (rtx mem_rtx)
1064 cselib_val **vp, *v, *next;
1068 mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
1069 mem_rtx = canon_rtx (mem_rtx);
1071 vp = &first_containing_mem;
1072 for (v = *vp; v != &dummy_val; v = next)
1074 bool has_mem = false;
1075 struct elt_loc_list **p = &v->locs;
1076 int had_locs = v->locs != 0;
1081 rtx canon_x = (*p)->canon_loc;
1083 struct elt_list **mem_chain;
1085 /* MEMs may occur in locations only at the top level; below
1086 that every MEM or REG is substituted by its VALUE. */
1087 if (GET_CODE (x) != MEM)
1093 canon_x = (*p)->canon_loc = canon_rtx (x);
1094 if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
1095 && ! canon_true_dependence (mem_rtx, GET_MODE (mem_rtx), mem_addr,
1096 x, cselib_rtx_varies_p))
1104 /* This one overlaps. */
1105 /* We must have a mapping from this MEM's address to the
1106 value (E). Remove that, too. */
1107 addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0);
1108 mem_chain = &addr->addr_list;
1111 if ((*mem_chain)->elt == v)
1113 unchain_one_elt_list (mem_chain);
1117 mem_chain = &(*mem_chain)->next;
1120 unchain_one_elt_loc_list (p);
1123 if (had_locs && v->locs == 0)
1126 next = v->next_containing_mem;
1130 vp = &(*vp)->next_containing_mem;
1133 v->next_containing_mem = NULL;
1138 /* Invalidate DEST, which is being assigned to or clobbered. The second and
1139 the third parameter exist so that this function can be passed to
1140 note_stores; they are ignored. */
1143 cselib_invalidate_rtx (rtx dest, rtx ignore ATTRIBUTE_UNUSED,
1144 void *data ATTRIBUTE_UNUSED)
1146 while (GET_CODE (dest) == STRICT_LOW_PART || GET_CODE (dest) == SIGN_EXTRACT
1147 || GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SUBREG)
1148 dest = XEXP (dest, 0);
1150 if (GET_CODE (dest) == REG)
1151 cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
1152 else if (GET_CODE (dest) == MEM)
1153 cselib_invalidate_mem (dest);
1155 /* Some machines don't define AUTO_INC_DEC, but they still use push
1156 instructions. We need to catch that case here in order to
1157 invalidate the stack pointer correctly. Note that invalidating
1158 the stack pointer is different from invalidating DEST. */
1159 if (push_operand (dest, GET_MODE (dest)))
1160 cselib_invalidate_rtx (stack_pointer_rtx, NULL_RTX, NULL);
1163 /* Record the result of a SET instruction. DEST is being set; the source
1164 contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT
1165 describes its address. */
1168 cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
1170 int dreg = GET_CODE (dest) == REG ? (int) REGNO (dest) : -1;
1172 if (src_elt == 0 || side_effects_p (dest))
1177 if (dreg < FIRST_PSEUDO_REGISTER)
1179 unsigned int n = HARD_REGNO_NREGS (dreg, GET_MODE (dest));
1181 if (n > max_value_regs)
1185 if (REG_VALUES (dreg) == 0)
1187 VARRAY_PUSH_UINT (used_regs, dreg);
1188 REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
1192 if (REG_VALUES (dreg)->elt == 0)
1193 REG_VALUES (dreg)->elt = src_elt;
1195 /* The register should have been invalidated. */
1199 if (src_elt->locs == 0)
1201 src_elt->locs = new_elt_loc_list (src_elt->locs, dest);
1203 else if (GET_CODE (dest) == MEM && dest_addr_elt != 0)
1205 if (src_elt->locs == 0)
1207 add_mem_for_addr (dest_addr_elt, src_elt, dest);
1211 /* Describe a single set that is part of an insn. */
1216 cselib_val *src_elt;
1217 cselib_val *dest_addr_elt;
1220 /* There is no good way to determine how many elements there can be
1221 in a PARALLEL. Since it's fairly cheap, use a really large number. */
1222 #define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
1224 /* Record the effects of any sets in INSN. */
1226 cselib_record_sets (rtx insn)
1230 struct set sets[MAX_SETS];
1231 rtx body = PATTERN (insn);
1234 body = PATTERN (insn);
1235 if (GET_CODE (body) == COND_EXEC)
1237 cond = COND_EXEC_TEST (body);
1238 body = COND_EXEC_CODE (body);
1241 /* Find all sets. */
1242 if (GET_CODE (body) == SET)
1244 sets[0].src = SET_SRC (body);
1245 sets[0].dest = SET_DEST (body);
1248 else if (GET_CODE (body) == PARALLEL)
1250 /* Look through the PARALLEL and record the values being
1251 set, if possible. Also handle any CLOBBERs. */
1252 for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
1254 rtx x = XVECEXP (body, 0, i);
1256 if (GET_CODE (x) == SET)
1258 sets[n_sets].src = SET_SRC (x);
1259 sets[n_sets].dest = SET_DEST (x);
1265 /* Look up the values that are read. Do this before invalidating the
1266 locations that are written. */
1267 for (i = 0; i < n_sets; i++)
1269 rtx dest = sets[i].dest;
1271 /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
1272 the low part after invalidating any knowledge about larger modes. */
1273 if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
1274 sets[i].dest = dest = XEXP (dest, 0);
1276 /* We don't know how to record anything but REG or MEM. */
1277 if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1279 rtx src = sets[i].src;
1281 src = gen_rtx_IF_THEN_ELSE (GET_MODE (src), cond, src, dest);
1282 sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1);
1283 if (GET_CODE (dest) == MEM)
1284 sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0), Pmode, 1);
1286 sets[i].dest_addr_elt = 0;
1290 /* Invalidate all locations written by this insn. Note that the elts we
1291 looked up in the previous loop aren't affected, just some of their
1292 locations may go away. */
1293 note_stores (body, cselib_invalidate_rtx, NULL);
1295 /* If this is an asm, look for duplicate sets. This can happen when the
1296 user uses the same value as an output multiple times. This is valid
1297 if the outputs are not actually used thereafter. Treat this case as
1298 if the value isn't actually set. We do this by smashing the destination
1299 to pc_rtx, so that we won't record the value later. */
1300 if (n_sets >= 2 && asm_noperands (body) >= 0)
1302 for (i = 0; i < n_sets; i++)
1304 rtx dest = sets[i].dest;
1305 if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1308 for (j = i + 1; j < n_sets; j++)
1309 if (rtx_equal_p (dest, sets[j].dest))
1311 sets[i].dest = pc_rtx;
1312 sets[j].dest = pc_rtx;
1318 /* Now enter the equivalences in our tables. */
1319 for (i = 0; i < n_sets; i++)
1321 rtx dest = sets[i].dest;
1322 if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1323 cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
1327 /* Record the effects of INSN. */
1330 cselib_process_insn (rtx insn)
1335 if (find_reg_note (insn, REG_LIBCALL, NULL))
1336 cselib_current_insn_in_libcall = true;
1337 if (find_reg_note (insn, REG_RETVAL, NULL))
1338 cselib_current_insn_in_libcall = false;
1339 cselib_current_insn = insn;
1341 /* Forget everything at a CODE_LABEL, a volatile asm, or a setjmp. */
1342 if (GET_CODE (insn) == CODE_LABEL
1343 || (GET_CODE (insn) == CALL_INSN
1344 && find_reg_note (insn, REG_SETJMP, NULL))
1345 || (GET_CODE (insn) == INSN
1346 && GET_CODE (PATTERN (insn)) == ASM_OPERANDS
1347 && MEM_VOLATILE_P (PATTERN (insn))))
1353 if (! INSN_P (insn))
1355 cselib_current_insn = 0;
1359 /* If this is a call instruction, forget anything stored in a
1360 call clobbered register, or, if this is not a const call, in
1362 if (GET_CODE (insn) == CALL_INSN)
1364 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1365 if (call_used_regs[i])
1366 cselib_invalidate_regno (i, reg_raw_mode[i]);
1368 if (! CONST_OR_PURE_CALL_P (insn))
1369 cselib_invalidate_mem (callmem);
1372 cselib_record_sets (insn);
1375 /* Clobber any registers which appear in REG_INC notes. We
1376 could keep track of the changes to their values, but it is
1377 unlikely to help. */
1378 for (x = REG_NOTES (insn); x; x = XEXP (x, 1))
1379 if (REG_NOTE_KIND (x) == REG_INC)
1380 cselib_invalidate_rtx (XEXP (x, 0), NULL_RTX, NULL);
1383 /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
1384 after we have processed the insn. */
1385 if (GET_CODE (insn) == CALL_INSN)
1386 for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
1387 if (GET_CODE (XEXP (x, 0)) == CLOBBER)
1388 cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0), NULL_RTX, NULL);
1390 cselib_current_insn = 0;
1392 if (n_useless_values > MAX_USELESS_VALUES)
1393 remove_useless_values ();
1396 /* Make sure our varrays are big enough. Not called from any cselib routines;
1397 it must be called by the user if it allocated new registers. */
1400 cselib_update_varray_sizes (void)
1402 unsigned int nregs = max_reg_num ();
1404 if (nregs == cselib_nregs)
1407 cselib_nregs = nregs;
1408 VARRAY_GROW (reg_values, nregs);
1409 VARRAY_GROW (used_regs, nregs);
1412 /* Initialize cselib for one pass. The caller must also call
1413 init_alias_analysis. */
1418 elt_list_pool = create_alloc_pool ("elt_list",
1419 sizeof (struct elt_list), 10);
1420 elt_loc_list_pool = create_alloc_pool ("elt_loc_list",
1421 sizeof (struct elt_loc_list), 10);
1422 cselib_val_pool = create_alloc_pool ("cselib_val_list",
1423 sizeof (cselib_val), 10);
1424 value_pool = create_alloc_pool ("value",
1425 RTX_SIZE (VALUE), 10);
1426 /* This is only created once. */
1428 callmem = gen_rtx_MEM (BLKmode, const0_rtx);
1430 cselib_nregs = max_reg_num ();
1431 if (reg_values_old != NULL && VARRAY_SIZE (reg_values_old) >= cselib_nregs)
1433 reg_values = reg_values_old;
1434 used_regs = used_regs_old;
1438 VARRAY_ELT_LIST_INIT (reg_values, cselib_nregs, "reg_values");
1439 VARRAY_UINT_INIT (used_regs, cselib_nregs, "used_regs");
1441 hash_table = htab_create_ggc (31, get_value_hash, entry_and_rtx_equal_p,
1443 cselib_current_insn_in_libcall = false;
1446 /* Called when the current user is done with cselib. */
1449 cselib_finish (void)
1451 free_alloc_pool (elt_list_pool);
1452 free_alloc_pool (elt_loc_list_pool);
1453 free_alloc_pool (cselib_val_pool);
1454 free_alloc_pool (value_pool);
1456 reg_values_old = reg_values;
1458 used_regs_old = used_regs;
1461 n_useless_values = 0;
1462 next_unknown_value = 0;
1465 #include "gt-cselib.h"