cselib.h

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/* Common subexpression elimination for GNU compiler.
   Copyright (C) 1987-2026 Free Software Foundation, Inc.
 
This file is part of GCC.
 
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
 
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.
 
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */
 
#ifndef GCC_CSELIB_H
#define GCC_CSELIB_H
 
/* Describe a value.  */
struct cselib_val
{
  /* A mask equivalent of HASH's bitfield width.  */
  static const unsigned int HASH_MASK = 0x3fffffff;
 
  /* The hash value.  */
  unsigned int hash : 30;
 
  /* True if this value is entered in cselib_preserved_hash_table.  */
  unsigned int in_preserved_table_p : 1;
 
  /* True if every value referenced by every element of LOCS is known
     to be a preserved value.  */
  unsigned int all_locs_preserved_p : 1;
 
  /* A unique id assigned to values.  */
  int uid;
 
  /* A VALUE rtx that points back to this structure.  */
  rtx val_rtx;
 
  /* All rtl expressions that hold this value at the current time during a
     scan.  */
  struct elt_loc_list *locs;
 
  /* If this value is used as an address, points to a list of values that
     use it as an address in a MEM.  */
  struct elt_list *addr_list;
 
  struct cselib_val *next_containing_mem;
};
 
/* A list of rtl expressions that hold the same value.  */
struct elt_loc_list {
  /* Next element in the list.  */
  struct elt_loc_list *next;
  /* An rtl expression that holds the value.  */
  rtx loc;
  /* The insn that made the equivalence.  */
  rtx_insn *setting_insn;
};
 
/* Describe a single set that is part of an insn.  */
struct cselib_set
{
  rtx src;
  rtx dest;
  cselib_val *src_elt;
  cselib_val *dest_addr_elt;
};
 
enum cselib_record_what
{
  CSELIB_RECORD_MEMORY = 1,
  CSELIB_PRESERVE_CONSTANTS = 2
};
 
extern void (*cselib_discard_hook) (cselib_val *);
extern void (*cselib_record_sets_hook) (rtx_insn *insn, struct cselib_set *sets,
                                        int n_sets);
 
extern cselib_val *cselib_lookup (rtx, machine_mode,
                                  int, machine_mode);
extern cselib_val *cselib_lookup_from_insn (rtx, machine_mode,
                                            int, machine_mode, rtx_insn *);
extern void cselib_init (int);
extern void cselib_clear_table (void);
extern void cselib_finish (void);
extern void cselib_process_insn (rtx_insn *);
extern bool fp_setter_insn (rtx_insn *);
extern machine_mode cselib_reg_set_mode (const_rtx);
extern bool rtx_equal_for_cselib_1 (rtx, rtx, machine_mode, int);
extern bool cselib_redundant_set_p (rtx);
extern bool references_value_p (const_rtx);
extern rtx cselib_expand_value_rtx (rtx, bitmap, int);
typedef rtx (*cselib_expand_callback)(rtx, bitmap, int, void *);
extern rtx cselib_expand_value_rtx_cb (rtx, bitmap, int,
                                       cselib_expand_callback, void *);
extern bool cselib_dummy_expand_value_rtx_cb (rtx, bitmap, int,
                                              cselib_expand_callback, void *);
extern rtx cselib_subst_to_values (rtx, machine_mode);
extern rtx cselib_subst_to_values_from_insn (rtx, machine_mode, rtx_insn *);
extern void cselib_invalidate_rtx (rtx);
 
extern void cselib_reset_table (unsigned int);
extern unsigned int cselib_get_next_uid (void);
extern void cselib_preserve_value (cselib_val *);
extern bool cselib_preserved_value_p (cselib_val *);
extern void cselib_preserve_only_values (void);
extern void cselib_preserve_cfa_base_value (cselib_val *, unsigned int);
extern void cselib_add_permanent_equiv (cselib_val *, rtx, rtx_insn *);
extern bool cselib_have_permanent_equivalences (void);
extern void cselib_set_value_sp_based (cselib_val *);
extern bool cselib_sp_based_value_p (cselib_val *);
extern void cselib_record_sp_cfa_base_equiv (HOST_WIDE_INT, rtx_insn *);
extern bool cselib_sp_derived_value_p (cselib_val *);
 
extern void dump_cselib_table (FILE *);
 
/* Return the canonical value for VAL, following the equivalence chain
   towards the earliest (== lowest uid) equivalent value.  */
 
inline cselib_val *
canonical_cselib_val (cselib_val *val)
{
  cselib_val *canon;
 
  if (!val->locs || val->locs->next
      || !val->locs->loc || GET_CODE (val->locs->loc) != VALUE
      || val->uid < CSELIB_VAL_PTR (val->locs->loc)->uid)
    return val;
 
  canon = CSELIB_VAL_PTR (val->locs->loc);
  gcc_checking_assert (canonical_cselib_val (canon) == canon);
  return canon;
}
 
/* Return true if we can prove that X and Y contain the same value, taking
   our gathered information into account.  */
 
inline bool
rtx_equal_for_cselib_p (rtx x, rtx y)
{
  if (x == y)
    return true;
 
  return rtx_equal_for_cselib_1 (x, y, VOIDmode, 0);
}
 
#endif /* GCC_CSELIB_H */